Method and apparatus for measuring material thickness

Claim 2

An automatic calibrating thickness measuring system comprising first means including a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and for producing an electrical signal represenative of the level of radiation received; a standards magazine responsive to an electrical control signal to place at least one radiation-attenuating standard in said path; second means for producing a first electrical control signal in response to a programmed anticipated first total thickness value and for coupling said signal to said standards magazines; means coupled to the output of said radiation detecting means for indicating the level of electrical signal supplied thereto, said means including adjustable gain means; means coupling the indicating means to said first means for generating a first feedback signal representing the level of electrical signal supplied to the indicating means, said first means being responsive to said feedback signal to drive the indicating means to indicate a first preselected value; means responsive to said indicating means indicating substantially said first value for terminating said feedback signal and for causing said second means to produce a second electrical control signal respresentative of a preselected deviation from said anticipated thickness value, said standards magazine being responsive to said second control signal to place at least one standard having a second total thickness in said path; and means for generating a second feedback signal to said adjustable gain means to adjust the gain thereof until said indicating means indicates a second preselected value with said second thickness in said path.

Claim 3

A system according to claim 1 wherein said second means comprises a source of pulses; a first pulse counter; a second pulse counter; means for programming said first pulse counter to produce a counter output signal after counting a given number of pulses; first and second pulse divider means for feeding pulses from said source to said first and second counters, the divisors of the two divider means and the programming of said first counter controlling the ratio of the number of pulses counted by said second counter to the given pulse number as programmed in said first counter; and menas responsive to said counter output signal of said first counter for applying a signal representative of the count in said second counter to said standards magazine as said first control signal.

Claim 4

A system according to claim 2 wherein said second means further comprises a third, bidirectional counter; third divider means for supplying to one input of said third counter a portion of the number of pulses delivered to said second counter to cause said third counter to count in a first direction from a datum count when said first counter is counting to said given number; and a gated path for delivering to a second input of said third counter the same number of pulses as is delivered to said second counter to cause said third counter to count in a direction opposite said first direction; and wherein said means responsive to said indicating means renders said gated path conductive and causes pulses to be delivered to said second and third counters until said third counter returns to said datum count, the count registered by said second counter representing said second control signal.

Claim 5

A system according to claim 1 wherein said means responsive to said indicating means includes, a repetitive analog-to-digital converter for receiving as an input the electrical signal supplied to said indicating means and for producing a pulse train output having a number of pulses proportional to the magnitude of the electrical signal and a converter output signal signifying the performance of each conversion; a first counter having a reset capability for counting the converter output signals and producing an output if said first counter counts a predetermined number of said converter output signals without being reset in the counting interim; and a second counter connected to count the pulses in each pulse train output from said converter and to reset said first counter each time a fixed number of pulses are counted by said second counter.

Claim 6

A system according to claim 4 and further comprising means connectable between said converter and said second counter when said standard having said second total thickness is in said path for accepting the pulse output of said converter and for subtracting the number of pulses in each pulse train from a preselected number, whereby said first counter produces said output.

Claim 7

A thickness measuring gauge comprising, a source of radiation, a standards magazine mounting a plurality of radiation-attenuating standards of predetermined thickness values, each of said standards being movable into a path of said radiation in response to a signal representative of a selected standard thickness, detection means mounted in said path of radiation for providing an analog electrical signal output having a magnitude which is a function of the radiation absorption characteristic of the material in said path, an analog meter coupled to said detection means for providing a visual display of changes in analog signal mangitude; first means programmable to provide a first signal representative of the nominal thickness of the material to be measured; second means programmable to provide a second signal representative of differences in the radiation absorption characteristics of the material to be measured and the standards material; third means responsive to said first and second signals to provide a digital output signal representative of the nominal material thickness value compensated by the radiation absorption characteristics of the material to be measured; fourth means coupling said third means to said standards magazine and actuated by said digital output signal of said third means for selectively inserting a standard into said radiation path having a total thickness as represented by said digital output signal; fifth means including a first feedback circuit operative with said standard in said radiation path for producing analog signal levels at the output of said detector means which tend to drive said meter to a null condition, said fifth means including a circuit which produces predetermined digital output signals when said condition obtains; sixth means coupled to said fourth means and to said fifth means and responsive to said predetermined digital output signals of said fifth means for actuating said fourth means to insert another standard into said radiation path corresponding to a predetermined value of material thickness deviation from nominal, and seventh means including a second feedback circuit coupling said circuit of said fifth means to said detection means and operative to drive said meter to indicate said predetermined value of thickness deviation.

Claim 8

A thickness measuring gauge comprising, a source of radiation, a standards magazine mounting a plurality of radiation-attenuating standards of predetermined thickness values, each of said standards being movable into a path of said radiation in response to a signal representative of a selected standard thickness, detection means mounted in said path of radiation for providing an analog electrical signal output having a magnitude which is a function of the radiation absorption characteristic of the material in said path, an analog meter coupled to said detection means for providing a visual display of changes in analog signal mangitude; first means programmable to provide a first signal representative of the nominal thickness of the material to be measured; second means programmable to provide a second signal representative of differences in the radiation absorption characteristics of the material to be measured and the standards material; third means responsive to said first and second signals to provide a digital output signal representative of the nominal material thickness value compensated by the radiation absorption characteristics of the material to be measured; fourth means coupling said third means to said standards magazine and actuated by said digital output signal of said third means for selectively inserting a standard into said radiation path having a total thickness as represented by said digital output signal; fifth means including a first feedback circuit operative with said standard in said radiation path for producing analog signal levels at the output of said detector means which tend to drive said meter to a null condition, said fifth means including a circuit which produces predetermined digital output signals when said condition obtains; sixth means coupled to said fourth means and to said fifth means and responsive to said predetermined digital output signals of said fifth means for actuating said fourth means to insert another standard into said radiation path corresponding to a predetermined value of material thickness deviation from nominal, and seventh means including a second feedback circuit coupling said circuit of said fifth means to said detection means and operative to drive said meter to indicate said predetermined value of thickness deviation.

Claim 9

In a measuring system, apparatus for detecting the existence of a preselected signal level at a point in an electrical circuit, within a determinable tolerance, the apparatus comprising: an analog-to-digital converter for receiving as an input the signal level at the point, and for producing by the end of each conversion cycle a group of pulses representative of the input signal level, and a converter signal signifying the cycle during which a pulse count of the group is produced; a first resettable counter connected to said converter for counting each converter signal and for producing a counter output signal each time the number of converter signals counted by said first counter exceeds a first predetermined number, said output signal being indicative of the arrival of the input signal at said signal level; and a second counter connected to said converter to count the pulses of each group and to reset said first counter in response to said second counter counting a given number of counts before said first counter produces a counter output signal; and wherein said converter is responsive to signal levels at said point of positive and negative polarity, and associates with each group of pulses a signal indication of the polarity of the received signal level, and

Claim 10

In a measuring system, apparatus for detecting the existence of a preselected signal level at a point in an electrical circuit, within a determinable tolerance, the apparatus comprising: an analog-to-digital converter for receiving as an input the signal level at the point, and for producing by the end of each conversion cycle a group of pulses representative of the input signal level, and a converter signal signifying the cycle during which a pulse count of the group is produced; a first resettable counter connected to said converter for counting each converter signal and for producing a counter output signal each time the number of converter signals counted by said first counter exceeds a first predetermined number, said output signal being indicative of the arrival of the input signal at said signal level; and a second counter connected to said converter to count the pulses of each group and to reset said first counter in response to said second counter counting a given number of counts before said first counter produces a counter output signal; and wherein said converter is responsive to signal levels at said point of positive and negative polarity, and associates with each group of pulses a signal indication of the polarity of the received signal level, and

Claim 11

wherein said second counter is bidirectionalwith the directions of counting determined by the polarity associated with each group of pulses, whereby said given number of counts is a net pulse count of the same polarity.

Claim 12

wherein said second counter is bidirectionalwith the directions of counting determined by the polarity associated with each group of pulses, whereby said given number of counts is a net pulse count of the same polarity.

Claim 13

The measuring system according to claim 7 wherein said converter output signal is a count transfer signal produced at the end of each conversion cycle, and wherein said given number of counts is less than the number of successive transfer signals which produce a counter output signal from said first counter.

Claim 16

The method according to claim 9 which further comprises the steps of: f. selecting the second value of material thickness representative of the maximum anticipated deviation from the nominal thickness value; g. irradiating a second standard sample having a thickness equivalent to the compensated maximum deviation of the material to be measured; h. producing an analog representation of the level of radiation emerging from the second standard sample; and then i. calibrating the apparatus to establish the latter analog representation at a second desired value by the process of (e).

Claim 17

A thickness measuring gauge comprising: gauging means including a source of radiation and a radiation detector adapted to receive radiation transmitted along a radiation path from said source for producing an analog output signal functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radition absorption characteristic and thickness of the material in said path; means for adjusting the operating level of said output signal; means for adjusting the rate of variation of said output signal; a standards magazine mounting a plurality of radiation-attenuating movable standards of predetermined thickness values; means for selectively inserting said standards into said path of radiation in response to signals representative of respective selected standard thicknesses; means for converting said analog output signal into a digital output signal; a first feedback circuit operable upon insertion in said radiation path of a first one of said standards having a composite thickness representative of a selected thickness value corresponding to that of the material to be measured and including means responsive to a first difference between the value of said digital output signal and a first predetermined digital value for controlling said operating level adjusting means to drive said digital output signal toward said first predetermined value for said selected thickness; and a second feedback circuit operable upon a second one of said standards being in position in said radiation path after termination of said first feedback circuit operation, said second standard having a composite thickness differing from the composite thickness of the first standard by an amount corresponding to a selected value of material thickness deviation, including means responsive to a second difference between the value of said digital output signal and a second predetermined digital value for controlling said rate of variation adjusting means to drive said digital output signal toward said second predetermined digital value for said selected value of material thickness deviation.

Claim 18

A thickness measuring gauge comprising: gauging means including a source of radiation and a radiation detector adapted to receive radiation transmitted along a radiation path from said source for producing an analog output signal functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radition absorption characteristic and thickness of the material in said path; means for adjusting the operating level of said output signal; means for adjusting the rate of variation of said output signal; a standards magazine mounting a plurality of radiation-attenuating movable standards of predetermined thickness values; means for selectively inserting said standards into said path of radiation in response to signals representative of respective selected standard thicknesses; means for converting said analog output signal into a digital output signal; a first feedback circuit operable upon insertion in said radiation path of a first one of said standards having a composite thickness representative of a selected thickness value corresponding to that of the material to be measured and including means responsive to a first difference between the value of said digital output signal and a first predetermined digital value for controlling said operating level adjusting means to drive said digital output signal toward said first predetermined value for said selected thickness; and a second feedback circuit operable upon a second one of said standards being in position in said radiation path after termination of said first feedback circuit operation, said second standard having a composite thickness differing from the composite thickness of the first standard by an amount corresponding to a selected value of material thickness deviation, including means responsive to a second difference between the value of said digital output signal and a second predetermined digital value for controlling said rate of variation adjusting means to drive said digital output signal toward said second predetermined digital value for said selected value of material thickness deviation.

Claim 19

The gauge of claim 11, wherein said operating level adjusting means includes means responsive to said first mentioned controlling means for adjusting the level of radiation emitted by said source of radiation.

Claim 20

The thickness measuring gauge of claim 11, wherein said first difference responsive means includes first means for storing a digital value to modify adjustment of said operating level adjusting means, said second difference responsive means includes second means for storing a digital value to modify adjustment of said rate of variation adjusting means, and said first and second feedback circuits include a common bidirectional counter operatively coupled to said converting means for counting first train pulses corresponding to said first difference during operation of said first feedback circuit to transfer a resulting count to said first storing means and for counting second train pulses corresponding to said second difference during operation of said second feedback circuit to transfer a resulting count to said second storing means, the direction of counting depending upon the polarity of the first and second differences respectively.

Claim 21

The thickness measuring gauge of claim 11, wherein said analog-to-digital converting means is responsive to said analog output signal during repeating conversion cycles for producing as said digital output signal a pulse train output having a number of pulses proportional to the magnitude of said analog output signal, and a conversion signal corresponding to each conversion cycle, and comprising: a resettable first counter connected to said converter to count the conversion signals and produce a first digital control signal each time the number of conversion signals counted by said first resettable counter exceeds a first predetermined number; and a second counter for counting pulses corresponding to said first and second difference respectively and coupled to said first counter to reset the same upon said second counter counting a second predetermined number of pulses before said first counter produces said first digital control signal, said first digital control signal thereby indicating upon completion of a number of such conversion cycles at least equal to said first predetermined number that the respective difference has been substantially nulled.

Claim 22

A thickness measuring gauge comprising: a gauging unit including a source of radiation and a radiation detector for receiving radiation transmitted along a radiation path from said source and for producing an signal output functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radiation absorption characteristics and thickness of material in said path; standards means for selectively establishing a plurality of radiation-attenuating movable standards of predetermined thickness values; first means programmable to provide a first representation of the nominal thickness of the material to be measured; second means programmable to provide a second representation of differences in the radiation absorption characteristics of the material to be measured and of the standards; and means responsive to said first and second representations for producing a standard control signal representative of the nominal material thickness compensated for the differences in the radiation absorption characteristics of the material to be measured and of the standards, said standards means being responsive to said standard control signal for selectively establishing one of said standards having a composite thickness represented by said standard control signal.

Claim 23

A thickness measuring gauge comprising: a gauging unit including a source of radiation and a radiation detector for receiving radiation transmitted along a radiation path from said source and for producing an signal output functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radiation absorption characteristics and thickness of material in said path; standards means for selectively establishing a plurality of radiation-attenuating movable standards of predetermined thickness values; first means programmable to provide a first representation of the nominal thickness of the material to be measured; second means programmable to provide a second representation of differences in the radiation absorption characteristics of the material to be measured and of the standards; and means responsive to said first and second representations for producing a standard control signal representative of the nominal material thickness compensated for the differences in the radiation absorption characteristics of the material to be measured and of the standards, said standards means being responsive to said standard control signal for selectively establishing one of said standards having a composite thickness represented by said standard control signal.

Claim 24

The thickness measuring gauge of claim 15 wherein said standard control signal producing means comprises: a clock pulse generator; a first pulse counter programmed by said first programmable means to produce a reference count signal upon counting a given number of pulses; a second pulse counter; first and second pulse divider means for feeding pulses from said generator to said first and second pulse counters respectively, at least one of said pulse divider means having a divisor responsive to said second programmable means; and means responsive to said reference count signal for interrupting counting by said second pulse counter, to produce said standard control signal corresponding to the count in said second pulse counter upon interruption of the counting thereof.

Claim 25

The thickness measuring gauge of claim 16, wherein said standard control signal producing means comprises: a bidirectional third counter; third divider means for supplying said bidirectional third counter with a selected portion of the number of pulses delivered to said second pulse counter to cause said bidirectional third counter to count in a first direction from a datum count until said first pulse counter reaches said given number; a gated path for enabling further delivery of pulses to said second counter and causing said bidirectional third counter to count these further pulses in a second direction opposite said first direction; and means responsive to said bidirectional third counter returning to said datum count for disabling said gated path to interrupt delivery of said further pulses and to produce another standard control signal representative of the count registered by said second pulse counter to activate said standards means to establish another of said standards in said radiation path.

Claim 26

The thickness measuring gauge of claim 15 comprising: a first feedback circuit coupled to said gauging unit and operable upon insertion in said radiation path of said one standard for adjusting an operating parameter of said gauging unit to drive said output signal toward a first predetermined value for said compensated nominal thickness; means responsive to said output signal taking said first predetermined value and coupled to said standards means for establishing another one of said standards having a composite thickness differing from that of said one standard by a predetermined compensated value of material thickness deviation from nominal to be placed in said radiation path; and a second feedback circuit operative after said other standard has been established in said path for adjusting a rate of amplification of said output signal to drive the same toward a second predetermined value for said compensated value of material thickness deviation.

Claim 29

The method of claim 19 further comprising: d. irradiating a second standard having a thickness differing from that of said first standard by an amount corresponding to a selected nominal thickness deviation of the material to be gauged compensated for said difference in radiation characteristics; and e. automtically adjusting a rate of amplification of the output signal to bring the same to a second predetermined level.

Claim 30

The method of claim 19, wherein said step of selecting comprises: producing a digital representation of the nominal thickness value of the given material; producing a digital representation of a compensating factor based on said difference in the radiation absorption characteristics; and modifying said nominal thickness digital representation by said compensating factor digital representation for producing a digital representation of said compensated nominal thickness value.

Claim 33

The method of claim 22, further comprising the steps of: irradiating a second calibration standard having a different thickness equal to a second selected thickness of the material to be gauged compensated for said difference in radiation absorption characteristics to produce a second resulting signal output from said radiation detector; and using said second resulting signal output to further calibrate the gauge for the material to be gauged.

Claim 34

The method of claim 23, wherein said second resulting signal output using step comprises automatically adjusting a parameter of gain of the radiation detector to bring the second resulting signal output to a second predetermined level.

Claim 35

The method of claim 22 comprising prior to said first standard irradiating step: producing a representation of said first selected thickness; producing a representation of a compensating factor based on said difference in the radiation absorption characteristics; modifying said first selected thickness representation by said compensating factor representation for producing a signal representative of an apparent value of the first selected thickness of the material to be gauged; and inserting said first standard in the path of radiation from said source to said detector in response to said apparent thickness representative signal.

Claim 36

The method of claim 22, wherein said first resulting signal output using step comprises automatically adjusting an operating parameter of the gauging unit to bring said first signal output to a first predetermined level.

Claim 37

The method of claim 26, further comprising: irradiating a second calibration standard having a different thickness corresponding to selected deviation of the first selected thickness of the material to be gauged compensated for said difference in radiation absorption characteristics to produce a second resulting signal output from said radiation detector; and automatically adjusting a parameter of gain of the radiation detector to bring the second resulting signal output to a second predetermined level.

Claim 38

A thickness measuring gauge comprising: a gauging unit including a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and for producing an output signal functionally related to the level of radiation received, said received radiation having a level which is a function of the radiation absorption characteristic and thickness of material in said path; and means for calibrating the gauge prior to inserting a material to be gauged in the radiation path, including: means for selectively establishing radiation attenuating standards of predetermined thickness values in the path of radiation, and control means responsive both to a signal representative of a selected thickness of a material to be gauged and to a signal functionally related to the difference in radiation absorption characteristics of the material to be gauged and of the standards for activating said selective establishing means to establish in said radiation path such a standard having a thickness equal to the apparent value of the selected thickness of the material to be gauged, so that the resulting output signal produced by said detecting means may be used in calibrating the gauge.

Claim 39

A thickness measuring gauge comprising: a gauging unit including a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and for producing an output signal functionally related to the level of radiation received, said received radiation having a level which is a function of the radiation absorption characteristic and thickness of material in said path; and means for calibrating the gauge prior to inserting a material to be gauged in the radiation path, including: means for selectively establishing radiation attenuating standards of predetermined thickness values in the path of radiation, and control means responsive both to a signal representative of a selected thickness of a material to be gauged and to a signal functionally related to the difference in radiation absorption characteristics of the material to be gauged and of the standards for activating said selective establishing means to establish in said radiation path such a standard having a thickness equal to the apparent value of the selected thickness of the material to be gauged, so that the resulting output signal produced by said detecting means may be used in calibrating the gauge.

Claim 40

The gauge of claim 28, comprising first settable means coupled to said control means for producing said signal representative of the selected thickness of a material to be gauged; and second settable means coupled to said control means for producing said signal functionally related to the difference in absorption characteristics of a material to be gauged and of said standards.

Claim 41

The gauge of claim 28, comprising means for automatically adjusting the value of an operating parameter of said gauging unit in response to the output signal produced by said detecting means after said standard having said apparent thickness value has been established in said radiation path to bring said output signal to a predetermined level.

Claim 42

The gauge of claim 28, comprising means for reactivating said standards establishing means after said standard has been established for establishing in said radiation path a second such standard having a thickness equal to the apparent value of a second selected thickness of the material to be gauged, so that the resulting output signal produced by the detecting means may be used in calibrating the gauge.

Claim 43

The gauge of claim 31, wherein said second selected thickness corresponds to a predetermined percentage deviation from the selected thickness of the material to be gauged.

Claim 44

The gauge of claim 31 comprising means operative after said second standard has been established for automatically adjusting the rate of variation of the output signal produced by said detecting means, until said output signal reaches a second predetermined level.

Claim 45

The gauge of claim 28, wherein said control means comprises: first means for counting clock pulses at a first rate, second means for counting the clock pulses at a second rate, at least one of said counting means being adjustable for setting the ratio of said second rate to said first rate for each material to be gauged at a compensation value corresponding to said difference in radiation absorption characteristics, third means for counting pulses issued from one of said first and second counting means at the respective rate up to a selected count corresponding to the selected thickness of the material to be gauged, and fourth means for counting pulses issued from the other of said first and second counting means at the respective rate to produce an output count representative of the apparent value of the selected thickness, in response to said third means reaching said selected count.

Claim 48

inserting into said radiation path a first thickness standard in response to said first representation to obtain a first value of said output signal corresponding to said first thickness value; producing a second representation of a predetermined deviation from said first thickness value; producing a third representation of a second thickness value corresponding to said predetermined deviation from said first thickness value in response to said first and second representations; establishing in said radiation path a second thickness standard in response to said third representation to obtain a second value of said output signal corresponding to said second thickness value; and calibrating the system in response to said first and second output signal values to reference indications of thickness variations produced in response to the output signal when a material is in said path with respect to said first and second thickness values.

Claim 49

inserting into said radiation path a first thickness standard in response to said first representation to obtain a first value of said output signal corresponding to said first thickness value; producing a second representation of a predetermined deviation from said first thickness value; producing a third representation of a second thickness value corresponding to said predetermined deviation from said first thickness value in response to said first and second representations; establishing in said radiation path a second thickness standard in response to said third representation to obtain a second value of said output signal corresponding to said second thickness value; and calibrating the system in response to said first and second output signal values to reference indications of thickness variations produced in response to the output signal when a material is in said path with respect to said first and second thickness values.

Claim 50

The method of claim 35, wherein said first signal is a count and said second signal is another count derived in response to said first count and representing a thickness deviation from said first thickness value corresponding to a predetermined percent variation thereof.

Claim 51

In a thickness measuring apparatus including: gauging means, having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and means for selectively establishing in said path of radiation a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising first calibrating means responsive to said output signal and operable after a first one of said standards having a composite thickness selected in accordance with the nominal thickness of a material to be gauged has been established in said radiation path for performing a first calibration of the apparatus for said nominal thickness, means automatically operable after said first calibration has been performed for producing a control signal to cause said standards establishing means to establish a second one of said standards the composite thickness of which exhibits a predetermined deviation from that of said first standard, and second calibrating means responsive to said output signal and operable after said second standard has been established in said radiation path for performing a second calibration of the apparatus.

Claim 52

In a thickness measuring apparatus including: gauging means, having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and means for selectively establishing in said path of radiation a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising first calibrating means responsive to said output signal and operable after a first one of said standards having a composite thickness selected in accordance with the nominal thickness of a material to be gauged has been established in said radiation path for performing a first calibration of the apparatus for said nominal thickness, means automatically operable after said first calibration has been performed for producing a control signal to cause said standards establishing means to establish a second one of said standards the composite thickness of which exhibits a predetermined deviation from that of said first standard, and second calibrating means responsive to said output signal and operable after said second standard has been established in said radiation path for performing a second calibration of the apparatus.

Claim 53

The system of claim 37, wherein said control signal producing means is responsive to termination of said first calibrtion step for producing said control signal and said second calibrating means is responsive to said control signal producing means to effect said second calibration after said second standard has been established in said radiation path.

Claim 54

The system of claim 37, comprising means responsive to indications of nominal thickness of the material to be gauged and of compensation for differences in radiation absorption characteristics of the material to be gauged and of said standards for activating said standards establishing means to establish as said first standard in said path a standard having a thickness equal to the apparent thickness of the material to be gauged.

Claim 55

In a thickness measuring apparatus including: gauging means, having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristic and thickness of material in said radiation path, the calibration system comprising: means for selectively establishing in said radiation path first and second radiation attenuating standards of respective first and second thicknesses in response to first and second control signals respectively; first calibrating means responsive to said first control signal and to said output signal for performing a first calibration of the apparatus after said first standard has been established in said path; means for producing a representation of said second thickness which corresponds to a predetermined deviation from said first thickness to enable said establishing means to establish said second standard in said path in response to said second control signal after said first calibration has been performed; and second calibrating means responsive to said second control signal and to said output signal for performing a second calibration of the apparatus after said second standard has been established in said path.

Claim 56

In a thickness measuring apparatus including: gauging means, having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristic and thickness of material in said radiation path, the calibration system comprising: means for selectively establishing in said radiation path first and second radiation attenuating standards of respective first and second thicknesses in response to first and second control signals respectively; first calibrating means responsive to said first control signal and to said output signal for performing a first calibration of the apparatus after said first standard has been established in said path; means for producing a representation of said second thickness which corresponds to a predetermined deviation from said first thickness to enable said establishing means to establish said second standard in said path in response to said second control signal after said first calibration has been performed; and second calibrating means responsive to said second control signal and to said output signal for performing a second calibration of the apparatus after said second standard has been established in said path.

Claim 57

The system of claim 40, including means for producing a representation of said first thickness to enable said establishing means to establish said first standard in said radiation path in response to said first control signal, and wherein said second thickness representation producing means is responsive to said first thickness representation.

Claim 58

The system of claim 41, wherein said second thickness representation producing means include means responsive to said first thickness representation for producing a representation of thickness change corresponding to said predetermined deviation to determine said second thickness representation.

Claim 59

The system of claim 40, including means responsive to termination of said first calibration for producing said second control signal to enable said establishing means to establish said second standard in said path.

Claim 60

The system of claim 40, wherein said first calibrating means includes means for adjusting the level of operation of said output signal, a first feedback circuit responsive to said adjusted output signal for controlling said adjusting means and means responsive to said first control signal for activating said first feedback circuit; said second calibrating means includes gain means for adjusting the rate of variation of said output signal, a second feedback circuit responsive to said gain adjusted output signal for controlling said gain means, and means responsive to said second control signal for activating said second feedback circuit; and including means responsive to stabilization of said level adjusting means under control of said first feedback circuit for terminating operation of said first feedback circuit and producing said second control signal after said second thickness representation has been produced.

Claim 61

The system of claim 40, wherein at least one of said calibrating means includes means for adjusting the level of radiation received in response to one of said first and second standards in said path.

Claim 62

In thickness measuring apparatus including: gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path: and means for selectively establishing radiation attenuating standards in said path of radiation; the calibration system comprising: means for producing a first control signal to cause said standards establishing means to establish in said path a first one of said standards having a first selected thickness, means responsive to the value of said output signal after said first standard has been established in said radiation path for initially calibrating the apparatus for said first selected thicknes, means responsive to a representation of said first selected thickness for producing a second control signal to cause said standards establishing means to establish in said path a second one of said standards having a second thickness corresponding to a predetermined deviation from said first thickness, and means responsive to the value of said output signal after said second standard has been established in said radiation path for completing the calibration of said apparatus with reference to said selected first thickness and predetermined deviation therefrom.

Claim 63

In thickness measuring apparatus including: gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path: and means for selectively establishing radiation attenuating standards in said path of radiation; the calibration system comprising: means for producing a first control signal to cause said standards establishing means to establish in said path a first one of said standards having a first selected thickness, means responsive to the value of said output signal after said first standard has been established in said radiation path for initially calibrating the apparatus for said first selected thicknes, means responsive to a representation of said first selected thickness for producing a second control signal to cause said standards establishing means to establish in said path a second one of said standards having a second thickness corresponding to a predetermined deviation from said first thickness, and means responsive to the value of said output signal after said second standard has been established in said radiation path for completing the calibration of said apparatus with reference to said selected first thickness and predetermined deviation therefrom.

Claim 64

In a thickness measuring apparatus including: gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and means for selectively establishing radiation attenuating standards in said path of radiation in response to respective representations of standard thickness values; the calibration system comprising: means for producing a first representation of a first selected standard thickness value; means responsive to said first representation for producing a second representation of a second standard thickness value corresponding to a predetermined deviation from the first standard thickness value; and means responsive to the values of said output signal corresponding to first and second standards of respective first and second thickness values established in the radiation path by said establishing means in response to said first and second representations respectively for calibrating the apparatus with reference to said first and second thickness values.

Claim 65

In a thickness measuring apparatus including: gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and means for selectively establishing radiation attenuating standards in said path of radiation in response to respective representations of standard thickness values; the calibration system comprising: means for producing a first representation of a first selected standard thickness value; means responsive to said first representation for producing a second representation of a second standard thickness value corresponding to a predetermined deviation from the first standard thickness value; and means responsive to the values of said output signal corresponding to first and second standards of respective first and second thickness values established in the radiation path by said establishing means in response to said first and second representations respectively for calibrating the apparatus with reference to said first and second thickness values.

Claim 66

The system of claim 47, wherein said first representation producing means is presettable to said first selected standard thickness value.

Claim 67

The system of claim 47, comprising presettable means coupled to said second representation producing means for selectively adjusting said predetermined deviation.

Claim 68

The system of claim 47 wherein said predetermined deviation is a percentage deviation of said first thickness value and said second representation producing means comprises means for producing a representation of a thickness deviation corresponding to said percentage.

Claim 69

In a thickness measuring apparatus including gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and a standards magazine for selectively establishing in said path a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising: means for producing a representation of a first thickness; means for converting said representation into a first count representative of the thickness of a first one of said standards; means for energizing said standards magazine in response to said first count to establish said first standard in said radiation path; means for converting said thickness representation into a second count representative of a thickness difference which is a predetermined function of said first thickness; said energizing means being responsive to said second count to insert into said radiation path a second one of said standards in replacement of said first standard, said second count being representative of the thickness difference between said first and second standards; and means for calibrating the gauging means in response to the values of the output signal of said radiation detecting means while said first and second standards are in said radiation path respectively.

Claim 70

In a thickness measuring apparatus including gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and a standards magazine for selectively establishing in said path a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising: means for producing a representation of a first thickness; means for converting said representation into a first count representative of the thickness of a first one of said standards; means for energizing said standards magazine in response to said first count to establish said first standard in said radiation path; means for converting said thickness representation into a second count representative of a thickness difference which is a predetermined function of said first thickness; said energizing means being responsive to said second count to insert into said radiation path a second one of said standards in replacement of said first standard, said second count being representative of the thickness difference between said first and second standards; and means for calibrating the gauging means in response to the values of the output signal of said radiation detecting means while said first and second standards are in said radiation path respectively.

Claim 71

The system of claim 51, wherein said energizing means includes means for modifying said first count by said second count to produce a third count representative of the thickness of said second standard.

Claim 72

In a thickness measuring apparatus including gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and a standards magazine for selectively establishing in said path a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising: means for activating said standards magazine to establish a first standard in said radiation path in response to a representation of a prescribed thickness value; means responsive to clock pulses for activating said standards magazine to establish in said radiation path a second standard having a thickness differing from that of said first standard by a predetermined factor and including: first means for counting at a first rate the clock pulses up to a count representative of said prescribed thickness, second means for counting the clock pulses and delivering output pulses at a different second rate determined by said factor until said first counting means reaches said representative count; third means for counting the output pulses of said second counting means from a starting count up to a count representative of a change in the prescribed thickness determined by the predetermined factor, said third means further being reversible as said first means begins counting beyond said representation count for counting the clock pulses from said change representative count back to said starting count; and fourth means responsive to said third means reaching said starting count for interrupting counting by said first counting means at a count which is representative of a thickness differing from said prescribed thickness by the predetermined factor; and means successively responsive to the values of said output signal when said first and second standards are in said radiation path for calibrating the apparatus.

Claim 73

In a thickness measuring apparatus including gauging means having a source of radiation and radiation detecting means for receiving radiation transmitted along a radiation path from said source and producing an output signal functionally related to the level of radiation received by said radiation detecting means, said received radiation level being a function of the radiation absorption characteristics and thickness of material in said radiation path; and a standards magazine for selectively establishing in said path a plurality of radiation attenuating standards of predetermined thickness values; the calibration system comprising: means for activating said standards magazine to establish a first standard in said radiation path in response to a representation of a prescribed thickness value; means responsive to clock pulses for activating said standards magazine to establish in said radiation path a second standard having a thickness differing from that of said first standard by a predetermined factor and including: first means for counting at a first rate the clock pulses up to a count representative of said prescribed thickness, second means for counting the clock pulses and delivering output pulses at a different second rate determined by said factor until said first counting means reaches said representative count; third means for counting the output pulses of said second counting means from a starting count up to a count representative of a change in the prescribed thickness determined by the predetermined factor, said third means further being reversible as said first means begins counting beyond said representation count for counting the clock pulses from said change representative count back to said starting count; and fourth means responsive to said third means reaching said starting count for interrupting counting by said first counting means at a count which is representative of a thickness differing from said prescribed thickness by the predetermined factor; and means successively responsive to the values of said output signal when said first and second standards are in said radiation path for calibrating the apparatus.

Claim 74

A thickness measuring gauge comprising: gauging means including a source of radiation and a radiation detector adapted to receive radiation transmitted along a radiation path from said source for producing a signal output functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radiation absorption characteristic and thickness of the material in said path; means for modifying the operating level of said signal output; means for modifying the rate of variation of said signal output; means for selectively establishing radiation attenuating standards in said path of radiation in response to signals representative of respective selected standards thicknesses; a first feedback circuit operable upon establishment said radiation path of a first one of said standards having a composite thickness representative of a selected thickness value corresponding to that of the material to be measured and including means responsive to a first difference between the value of said signal output and a first predetermined value for adjusting said operating level modifying means to drive said signal output toward said first predetermined value for said selected thickness value; and a second feedback circuit operable upon establishment of a second one of said standards in said radiation path after termination of said first feedback circuit operation, said second standard having a composite thickness differing from the coupling thickness of the first standard by an amount corresponding to a selected value of material thickness deviation, including means responsive to a second difference between the output of said rate of variation modifying means and a second predetermined value for adjusting said rate of variation modifying means to drive said output thereof toward said second predetermined value for said selected value of material thickness deviation.

Claim 75

A thickness measuring gauge comprising: gauging means including a source of radiation and a radiation detector adapted to receive radiation transmitted along a radiation path from said source for producing a signal output functionally related to the level of radiation received, said received radiation having a magnitude which is a function of the radiation absorption characteristic and thickness of the material in said path; means for modifying the operating level of said signal output; means for modifying the rate of variation of said signal output; means for selectively establishing radiation attenuating standards in said path of radiation in response to signals representative of respective selected standards thicknesses; a first feedback circuit operable upon establishment said radiation path of a first one of said standards having a composite thickness representative of a selected thickness value corresponding to that of the material to be measured and including means responsive to a first difference between the value of said signal output and a first predetermined value for adjusting said operating level modifying means to drive said signal output toward said first predetermined value for said selected thickness value; and a second feedback circuit operable upon establishment of a second one of said standards in said radiation path after termination of said first feedback circuit operation, said second standard having a composite thickness differing from the coupling thickness of the first standard by an amount corresponding to a selected value of material thickness deviation, including means responsive to a second difference between the output of said rate of variation modifying means and a second predetermined value for adjusting said rate of variation modifying means to drive said output thereof toward said second predetermined value for said selected value of material thickness deviation.

Claim 76

The gauge of claim 54, comprising: means for producing a first of said thickness representative signals for establishing said first standard in said path, said first feedback circuit being responsive to said first signal for beginning to operate; means responsive to said output signal reaching said first predetermined value for terminating operation of said first feedback circuit; and means responsive to said output signal reaching said first predetermined value for producing a second of said thickness representative signals for establishing said second standard in said path, said second feedback circuit being responsive to said second signal for beginning to operate.

Claim 77

The gauge of claim 54, wherein said operating level modifying means includes means for adjusting the level of radiation emitted by said source.

Claim 78

The gauge of claim 54, wherein said rate of variation modifying means includes a variable gain amplifier responsive to said signal output.

Claim 81

The method of claim 58, wherein said second thickness corresponds to a predetermined deviation from said first thickness.

Claim 82

The method of claim 59, wherein said predetermined deviation is a thickness value representing a predetermined percentage variation of said first thickness.

Claim 83

The method of claim 58, wherein the converting step comprises: producing an output signal functionally related to the level of emerging radiation; adjusting the value of the output signal produced in response to said first level of emerging radiation to a first predetermined value; and modifying the rate of variation of said output signal to adjust the value of said output signal produced in response to said second level of emerging radiation to a second predetermined value, whereby said output signal provides said calibrated indications of thickness variations.

Claim 84

A thickness measuring apparatus comprising: gauge means for defining a path of radiation and for producing indications varying with thickness of a material in said path in response to the level of radiation emerging therefrom; means respectively responsive to first and second signals corresponding to first and second reference thickness values for sequentially establishing first and second thickness standards corresponding to said first and second thickness values in said path, respectively; and calibration means for calibrating said gauge means in response to the first and second levels of radiation emerging respectively when said first standard is in said path and when said second standard is in said path to reference the indications produced when a material of varying thickness is in said path to said first and second thickness values.

Claim 85

A thickness measuring apparatus comprising: gauge means for defining a path of radiation and for producing indications varying with thickness of a material in said path in response to the level of radiation emerging therefrom; means respectively responsive to first and second signals corresponding to first and second reference thickness values for sequentially establishing first and second thickness standards corresponding to said first and second thickness values in said path, respectively; and calibration means for calibrating said gauge means in response to the first and second levels of radiation emerging respectively when said first standard is in said path and when said second standard is in said path to reference the indications produced when a material of varying thickness is in said path to said first and second thickness values.

Claim 86

The apparatus of claim 62, wherein said calibration means comprises feedback means for adjusting the indications produced when one of said first and second standards is in said path.

Claim 87

The apparatus of claim 62, wherein said calibration means comprises first feedback means for adjusting the level of radiation emitted toward the material in said path in response to said first level of emerging radiation, and second feedback means for adjusting the rate of variation of the produced indications in response to said second level of emerging radiation.

Claim 88

The apparatus of claim 62, wherein said second thickness reference value corresponds to a predetermined deviation from said first thickness value, and comprising first means for producing said first signal corresponding to said first reference thickness value and second means responsive to said first signal for producing said second signal.

Claim 89

The apparatus of claim 62, comprising means for producing said first and second signals which include means for sequentially producing counts representative of the thickness of said first and second standards to activate said standard establishing means for establishing said first and second standrds in said path.