US3904833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ringing generator circuit with capacitor storage
Assignee: Superior Continental Corp
•
Filing: 1973-06-04
•
Granted: 1975-09-09
•
Expires: 1993-06-04
Abstract
Abstract A ringing generator circuit in which a capacitor is charged by the central office d.c. power source and in which the charge stored by the capacitor is applied, in response to a ring control signal, to activate the subscriber''s ringer or other signalling device to signal an incoming call.
Inventors
- 👤 Gerald Wayne Beene
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 19:30
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/02; H04M19/04; H04M7/00; H04M7/16
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
218 words
A ringing generator circuit for energizing the signalling device of a telephone in a telephone transmission system having (a) a transmission line which provides a connection for transmitting signals between a central office and said telephone, (b) a d.c. power source located at said central office and electrically connected to said line to apply voltage thereto, and (c) means for providing a pre-selected signal to signal an incoming call for said telephone, said ringing generator circuit comprising a capacitor for storing an electrical charge to provide a source of emf for energizing said signalling device, means responsive to said pre-selected signal to apply the charge stored by said capacitor to energize said signalling device, and circuit means electrically connecting said capacitor to said line to charge said capacitor from said d.c. power source, said circuit means comprising an oscillator having an output connected to one terminal of said capacitor to build up the voltage across said capacitor, a transistor connected to the input of said oscillator for controlling the supply of current thereto, and a zener diode connected between the base terminal of said transistor and said one terminal of said capacitor, said diode being effective to control the amount of current conducted by said transistor to limit the voltage build-up across said capacitor to a pre-selected magnitude.
Claim 2
Dependent Claim
218 words
A ringing generator circuit for energizing the signalling device of a telephone in a telephone transmission system having (a) a transmission line which provides a connection for transmitting signals between a central office and said telephone, (b) a d.c. power source located at said central office and electrically connected to said line to apply voltage thereto, and (c) means for providing a pre-selected signal to signal an incoming call for said telephone, said ringing generator circuit comprising a capacitor for storing an electrical charge to provide a source of emf for energizing said signalling device, means responsive to said pre-selected signal to apply the charge stored by said capacitor to energize said signalling device, and circuit means electrically connecting said capacitor to said line to charge said capacitor from said d.c. power source, said circuit means comprising an oscillator having an output connected to one terminal of said capacitor to build up the voltage across said capacitor, a transistor connected to the input of said oscillator for controlling the supply of current thereto, and a zener diode connected between the base terminal of said transistor and said one terminal of said capacitor, said diode being effective to control the amount of current conducted by said transistor to limit the voltage build-up across said capacitor to a pre-selected magnitude.
Claim 3
Dependent Claim
142 words
In a telephone carrier transmission system having at least one telephone, a ringer for said telephone, a first capacitor connected in series with said ringer and effective upon being alternately charged and discharged to energize said ringer, a two-conductor transmission line providing a connection for transmitting signals between a central office and said telephone, a d.c. power source located at said central office and electrically connected to said line to apply voltage thereto, and means for supplying a pre-selected signal to signal an incoming call for said telephone, the improvement comprising a second capacitor, means electrically connecting said second capacitor to said line to charge said second capacitor from said d.c. power source, and a circuit responsive to said pre-selected signal for alternately charging said first capacitor from the charge which is stored by said second capacitor and discharging said first capacitor.
Claim 4
Dependent Claim
142 words
In a telephone carrier transmission system having at least one telephone, a ringer for said telephone, a first capacitor connected in series with said ringer and effective upon being alternately charged and discharged to energize said ringer, a two-conductor transmission line providing a connection for transmitting signals between a central office and said telephone, a d.c. power source located at said central office and electrically connected to said line to apply voltage thereto, and means for supplying a pre-selected signal to signal an incoming call for said telephone, the improvement comprising a second capacitor, means electrically connecting said second capacitor to said line to charge said second capacitor from said d.c. power source, and a circuit responsive to said pre-selected signal for alternately charging said first capacitor from the charge which is stored by said second capacitor and discharging said first capacitor.
Claim 5
Dependent Claim
85 words
The telephone carrier transmission system defined in claim 2 wherein said circuit comprises means under the control of said pre-selected signal for supplying a switching signal, and switching means under the control of said switching signal to alternately complete intermittent charging and discharging circuits for said first capacitor, said charging circuit, upon being completed, providing a current-conducting circuit connection between said first and seconc capacitors to charge said first capacitor from current flow that is caused by the voltage built up across said second capacitor.
Claim 6
Dependent Claim
16 words
The telephone carrier transmission system dEfined in claim 3 wherein said switching means comprises transistor means.
Claim 7
Dependent Claim
100 words
The telephone carrier transmission system defined in claim 2 wherein said circuit comprises first and second transistors, and a pulse generator responsive to said pre-selected signal to supply pulses to said transistors for alternately switching said transistors into conduction, said first transistor being effective upon being switched into conduction to complete a circuit between said first and second capacitors to charge said first capacitor with flow of current that is caused by the voltage built up across said second capacitor, and said second transistor being effective upon being switched into conduction to complete a circuit for discharging said first capacitor.
Claim 8
Dependent Claim
194 words
In a telephone carrier transmission system, at least one carrier channel unit, at least one subscriber terminal unit, at least one telephone electrically connected to said subscriber terminal unit, said carrier channel unit being located at a central office station, and said subscriber terminal unit being located at a subscriber''s station which is remote from said central office station, said carrier channel unit having means for continuously transmitting a carrier signal of pre-selected frequency and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone a two-conductor transmission line providing a signal-transmitting connection between said units for transmitting carrier signals from one unit to the other, a capacitor at said subscriber''s station, means electrically connecting said capacitor to said line, a source of d.c. potential located at said central office station and electrically connected to said line to supply current for charging said capacitor, means in said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, and a circuit responsive to said predetermined signal for applying the charge stored by said capacitor to ring said telephone.
Claim 9
Dependent Claim
194 words
In a telephone carrier transmission system, at least one carrier channel unit, at least one subscriber terminal unit, at least one telephone electrically connected to said subscriber terminal unit, said carrier channel unit being located at a central office station, and said subscriber terminal unit being located at a subscriber''s station which is remote from said central office station, said carrier channel unit having means for continuously transmitting a carrier signal of pre-selected frequency and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone a two-conductor transmission line providing a signal-transmitting connection between said units for transmitting carrier signals from one unit to the other, a capacitor at said subscriber''s station, means electrically connecting said capacitor to said line, a source of d.c. potential located at said central office station and electrically connected to said line to supply current for charging said capacitor, means in said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, and a circuit responsive to said predetermined signal for applying the charge stored by said capacitor to ring said telephone.
Claim 10
Independent Claim
95 words
A method of energizing a signalling device which is associated with a subscriber''s telephone to signal an incoming call in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding direct current over said line from a d.c. power source at said central office to charge a capacitor at the subscriber''s end of said line, and applying the charge stored by said capacitor to energize said signalling device upon the occurrence of a preselected modulation of a carrier signal.
Claim 11
Independent Claim
95 words
A method of energizing a signalling device which is associated with a subscriber''s telephone to signal an incoming call in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding direct current over said line from a d.c. power source at said central office to charge a capacitor at the subscriber''s end of said line, and applying the charge stored by said capacitor to energize said signalling device upon the occurrence of a preselected modulation of a carrier signal.
Claim 12
Independent Claim
148 words
A method of ringing a ringer of a subscriber''s telephone in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding current over said line from a d.c. power source which is located at said central office to charge a capacitor at the subscriber''s end of said line in preparation for ringing said ringer, causing said ringer to have alternately occurring ringing and silent intervals in which said ringer is respectively energized and de-energized by discharging said capacitor only during said ringing intervals to provide for flow of current through said ringer during said ringing intervals, and re-charging said capacitor from said source during said ringing intervals and said silent intervals to at least substantially restore said voltage to said pre-selected value by the time each of the ringing intervals is initiated.
Claim 13
Independent Claim
148 words
A method of ringing a ringer of a subscriber''s telephone in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding current over said line from a d.c. power source which is located at said central office to charge a capacitor at the subscriber''s end of said line in preparation for ringing said ringer, causing said ringer to have alternately occurring ringing and silent intervals in which said ringer is respectively energized and de-energized by discharging said capacitor only during said ringing intervals to provide for flow of current through said ringer during said ringing intervals, and re-charging said capacitor from said source during said ringing intervals and said silent intervals to at least substantially restore said voltage to said pre-selected value by the time each of the ringing intervals is initiated.
Claim 14
Independent Claim
121 words
A method of energizing the ringer of a subscriber''s telephone which is located remotely from a central office in a telephone carrier system, said method comprising the steps of charging a capacitor from current supplied by a d.c. voltage source which is located at said central office in preparation for ringing said ringer, causing said ringer to have alternately occurring ringing and silent intervals in which saId ringer is respectively energized and de-energized by discharging said capacitor to energize said ringer only during the ringing intervals, and recharging said capacitor from said source during said ringing and said silent intervals and independently of the discharging of said capacitor as long as the voltage across said capacitor is below a pre-selected value.
Claim 15
Independent Claim
121 words
A method of energizing the ringer of a subscriber''s telephone which is located remotely from a central office in a telephone carrier system, said method comprising the steps of charging a capacitor from current supplied by a d.c. voltage source which is located at said central office in preparation for ringing said ringer, causing said ringer to have alternately occurring ringing and silent intervals in which saId ringer is respectively energized and de-energized by discharging said capacitor to energize said ringer only during the ringing intervals, and recharging said capacitor from said source during said ringing and said silent intervals and independently of the discharging of said capacitor as long as the voltage across said capacitor is below a pre-selected value.
Claim 16
Independent Claim
197 words
A method of energizing a ringer of a subscriber''s telephone in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding current over said line from a direct current source which is located at said central office to charge a capacitor at the subscriber''s end of said line in preparation for energizing said ringer, supplying a pre-selected signal having alternately occurring ringing and silent intervals at said central office to signal a call coming into said telephone, modulating a carrier signal with said preselected signal and transmitting the modulated carrier signal down said line to a subscriber''s station at which said telephone is located, detecting said modulated carrier signal at said station to derive a predetermined signal which has ringing and silent intervals corresponding to that of said pre-selected signal, utilizing the charge stored by said capacitor to effect the flow of alternating current through said ringer to energize said ringer during each occurrence of only the ringing intervals of said predetermined signal, and re-charging said capacitor from said source during both the ringing and silent intervals of said predetermined signal.
Claim 17
Independent Claim
197 words
A method of energizing a ringer of a subscriber''s telephone in a telephone carrier system which has a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of feeding current over said line from a direct current source which is located at said central office to charge a capacitor at the subscriber''s end of said line in preparation for energizing said ringer, supplying a pre-selected signal having alternately occurring ringing and silent intervals at said central office to signal a call coming into said telephone, modulating a carrier signal with said preselected signal and transmitting the modulated carrier signal down said line to a subscriber''s station at which said telephone is located, detecting said modulated carrier signal at said station to derive a predetermined signal which has ringing and silent intervals corresponding to that of said pre-selected signal, utilizing the charge stored by said capacitor to effect the flow of alternating current through said ringer to energize said ringer during each occurrence of only the ringing intervals of said predetermined signal, and re-charging said capacitor from said source during both the ringing and silent intervals of said predetermined signal.
Claim 18
Dependent Claim
167 words
A ringing generator circuit for energizing the signalling device of a telephone which is electrically connected to a subscriber terminal unit in a telephone carrier system having (a) a transmission line connecting said subscriber terminal unit to a central office station, (b) a direct current source located at said central office station and electrically connected to said line, (c) a transmitter at said central office for applying a carrier signal to said line and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone, and (d) means at said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, said ringing generator circuit comprising a capacitor, means adapted to electrically connect said capacitor to said line to charge said capacitor by current fed over said line from said source, and circuit means responsive to said predetermined signal for applying the charge stored on said capacitor to energize said signalling device.
Claim 19
Dependent Claim
167 words
A ringing generator circuit for energizing the signalling device of a telephone which is electrically connected to a subscriber terminal unit in a telephone carrier system having (a) a transmission line connecting said subscriber terminal unit to a central office station, (b) a direct current source located at said central office station and electrically connected to said line, (c) a transmitter at said central office for applying a carrier signal to said line and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone, and (d) means at said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, said ringing generator circuit comprising a capacitor, means adapted to electrically connect said capacitor to said line to charge said capacitor by current fed over said line from said source, and circuit means responsive to said predetermined signal for applying the charge stored on said capacitor to energize said signalling device.
Claim 20
Dependent Claim
34 words
The ringing generator circuit defined in claim 11, wherein said means adapted to electrically connect said capacitor to said line comprises a d.c.-to-d.c. converter which applies a stepped-up pulsating voltage for charging said capacitor.
Claim 21
Dependent Claim
65 words
The ringing generator circuit defined in claim 4 wherein signalling device comprises a ringer, wherein said predetermined signal has different alternately occurring voltage conditions, and wherein said circuit means responsive to said predetermined signal comprises a circuit controlled by said voltage conditions to energize and thereby ring said ringer only during intermittent intervals which are interrupted by silent intervals in which said ringer is de-energized.
Claim 22
Dependent Claim
39 words
The ringing generator circuit defined in claim 4 wherein said means adapted to electrically connect said capacitor to said line comprises a circuit which applies a charging voltage across said capacitor and which is independent of said circuit means.
Claim 23
Dependent Claim
28 words
The ringing generator circuit defined in claim 11 wherein said circuit means comprises a circuit for discharging said capacitor independently of the instantaneous polarity of said carrier signal.
Claim 24
Dependent Claim
71 words
The ringing generator circuit defined in claim 11 wherein said circuit means comprises a switching circuit for discharging said capacitor and wherein said means adapted to electrically connect said capacitor to said line comprising a circuit which is effective to apply a charging voltage across said capacitor independently of whether said switching circuit is discharging said capacitor as long as the voltage across said capacitor is less than a pre-selected value.
Claim 25
Dependent Claim
40 words
The ringing generator circuit defined in claim 12 wherein said converter comprises an oscillator which supplies said pulsating voltage and means for turning off said oscillator in response to an increase in voltage across said capacitor to a preselected value.
Claim 26
Dependent Claim
39 words
The ringing generator circuit in claim 11 wherein said signalling device comprises a ringer and wherein said circuit means comprises a circuit for operating said ringer at a frequency which is independent of the frequency of said carrier signal.
Claim 27
Dependent Claim
39 words
The ringing generator circuit defined in claim 11, including means for capacitively coupling said circuit means to said signalling device and cooperating with said circuit means for feeding alternating current through said signalling device for energizing said signalling device.
Claim 28
Dependent Claim
200 words
In a telephone signalling circuit for signalling an incoming call for a telephone instrument in a telephone carrier system having (a) a transmission line connecting a subscriber terminal unit to a central office, (b) a direct current source located at said central office and electrically connected to said line to apply d.c. voltage to the line, (c) a transmitter at said central office for applying a carrier signal to said line and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone instrument, and (d) means at said subscriber terminal unit for detecting the carrier signal which is modulated by said pre-selected signal to derive a pre-determined signal, said signalling circuit comprising a ringer, a first capacitor connected in series with said ringer, a second capacitor, means adapted to electrically connect said second capacitor to said line to charge said second capacitor by current fed over said line from said source, and means responsive to said predetermined signal for alternately charging said first capacitor from the charge stored on said second capacitor and for discharging said first capacitor to provide for the flow of alternating current through said ringer to energize the ringer.
Claim 29
Dependent Claim
200 words
In a telephone signalling circuit for signalling an incoming call for a telephone instrument in a telephone carrier system having (a) a transmission line connecting a subscriber terminal unit to a central office, (b) a direct current source located at said central office and electrically connected to said line to apply d.c. voltage to the line, (c) a transmitter at said central office for applying a carrier signal to said line and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone instrument, and (d) means at said subscriber terminal unit for detecting the carrier signal which is modulated by said pre-selected signal to derive a pre-determined signal, said signalling circuit comprising a ringer, a first capacitor connected in series with said ringer, a second capacitor, means adapted to electrically connect said second capacitor to said line to charge said second capacitor by current fed over said line from said source, and means responsive to said predetermined signal for alternately charging said first capacitor from the charge stored on said second capacitor and for discharging said first capacitor to provide for the flow of alternating current through said ringer to energize the ringer.
Claim 30
Dependent Claim
191 words
In combination with a telephone carrier transmission system having at least one telephone which has a ringer, at least one central office-located carrier channel unit which includes means for transmitting a carrier signal of pre-selected frequency and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone, at least one subscriber terminal unit, a transmission line providing a signal-transmitting connection between said carrier channel unit and said subscriber terminal unit for feeding said carrier signal to said subscriber terminal unit, means in said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, and a central office-located direct current source electrically connected to said line to supply direct current to said line while said carrier signal is being transmitted, a capacitor, means electrically connecting said capacitor to said line to charge said capacitor from current fed via said line from said source, and a circuit electrically connected to said ringer, said capacitor and said detecting means and responsive to said predetermined signal to apply the charge stored by said capacitor to ring said ringer.
Claim 31
Dependent Claim
191 words
In combination with a telephone carrier transmission system having at least one telephone which has a ringer, at least one central office-located carrier channel unit which includes means for transmitting a carrier signal of pre-selected frequency and for modulating said carrier signal with a pre-selected signal to signal an incoming call to said telephone, at least one subscriber terminal unit, a transmission line providing a signal-transmitting connection between said carrier channel unit and said subscriber terminal unit for feeding said carrier signal to said subscriber terminal unit, means in said subscriber terminal unit for detecting the carrier signal which is modulated by said preselected signal to derive a predetermined signal, and a central office-located direct current source electrically connected to said line to supply direct current to said line while said carrier signal is being transmitted, a capacitor, means electrically connecting said capacitor to said line to charge said capacitor from current fed via said line from said source, and a circuit electrically connected to said ringer, said capacitor and said detecting means and responsive to said predetermined signal to apply the charge stored by said capacitor to ring said ringer.
Claim 32
Dependent Claim
68 words
The combination defined in claim 13 wherein said means electrically connecting said capacitor to said line includes a circuit having an oscillator which is energized by current drawn from said source to apply a pulsating voltage across said capacitor to charge said capacitor, and means responsive to the voltage across said capacitor to turn ofF said oscillator when the voltage across said capacitor increases to a pre-selected value.
Claim 33
Dependent Claim
29 words
The combination defined in claim 21 wherein said means electrically connecting said capacitor to said line comprises a d.c.-to-d.c. converter which applies a stepped-up voltage to charge said capacitor.
Claim 34
Dependent Claim
124 words
The combination defined in claim 21 wherein said pre-selected signal when signalling an incoming call intermittently modulates said carrier signal to provide alternating ringing and silent intervals in which said carrier signal is respectively modulated and unmodulated by said pre-selected signal, wherein said detecting means provides said predetermined signal with an intermittent wave form which is present throughout each ringing interval, but absent throughout each silent interval, and wherein said circuit responsive to said predetermined signal is controlled by the presence and absence of said wave form to intermittently complete a circuit for feeding current from said capacitor to said ringer throughout each ringing interval and to prevent the charge on said capacitor from being applied to energize said ringer throughout each silent interval.
Claim 35
Dependent Claim
85 words
The combination defined in claim 16 wherein said means electrically connecting said capacitor to said line provides for the charging of said capacitor to a pre-selected voltage prior to the occurrence of said predetermined signal and additionally during said silent and ringing intervals and at a rate which is slower than the rate at which said capacitor is discharged to energize said ringer, but fast enough to substantially restore the charge to said pre-selected voltage by the time each of the ringing intervals is initiated.
Claim 36
Dependent Claim
58 words
The combination defined in claim 21 wherein said means electrically connecting said capacitor to said line comprises a circuit which charges said capacitor with current drawn from said source as long as the voltage built up across said capacitor is less than a pre-selected value and independently of the instantaneous polarities of said carrier, pre-selected and predetermined signals.
Claim 37
Dependent Claim
73 words
The combination defined in claim 21 wherein said circuit responsive to said predetermined signal includes means which completes a circuit for discharging said capacitor, and wherein said means electrically connecting said capacitor to said line includes a circuit which provides for the charging of said capacitor from current drawn from said source independently of the discharging of said capacitor as long as the voltage across said capacitor is less than a pre-selected value.
Claim 38
Dependent Claim
31 words
The combination defined in claim 21, including means capacitively coupling said ringer to said circuit and cooperating with said circuit to feed alternating current through said ringer for energizing said ringer.
Claim 39
Dependent Claim
31 words
The combination defined in claim 24, including means capacitively coupling said ringer to said circuit and cooperating with said circuit to feed alternating current through said ringer for energizing said ringer.
Claim 40
Independent Claim
103 words
A method of energizing the ringer of a subscriber''s telephone in a telephone carrier system having a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of charging a capacitor at the subscriber''s end of said line from current drawn via said line from a central office-located direct current source, providing a pre-selected modulation of a carrier signal to signal an incoming call to said telephone, and feeding current by way of a capacitive coupling from said capacitor to said ringer to energize said ringer with a.c. current upon the occurrence of said pre-selected modulation.
Claim 41
Independent Claim
103 words
A method of energizing the ringer of a subscriber''s telephone in a telephone carrier system having a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of charging a capacitor at the subscriber''s end of said line from current drawn via said line from a central office-located direct current source, providing a pre-selected modulation of a carrier signal to signal an incoming call to said telephone, and feeding current by way of a capacitive coupling from said capacitor to said ringer to energize said ringer with a.c. current upon the occurrence of said pre-selected modulation.
Claim 42
Independent Claim
147 words
A method of energizing the ringer of a subscriber''s telephone with alternating current in a telephone carrier system having a first capacitor in series with said ringer, and a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of charging a further capacitor at the subscriber''s end of said line from current drawn via said line from a central office-located direct current source, providing a pre-selected signal to signal an incoming call to said telephone, intermittently discharging said further capacitor upon the occurrence of said pre-selected signal to intermittently charge said first capacitor, and discharging said first capacitor during each period between the successively occurring intervals in which said first capacitor is being charged to effect the alternate charging and discharging of said first capacitor for causing an alternating current to flow through the ringer to energize the ringer.
Claim 43
Independent Claim
147 words
A method of energizing the ringer of a subscriber''s telephone with alternating current in a telephone carrier system having a first capacitor in series with said ringer, and a transmission line for transmitting signals between said telephone and a central office, said method comprising the steps of charging a further capacitor at the subscriber''s end of said line from current drawn via said line from a central office-located direct current source, providing a pre-selected signal to signal an incoming call to said telephone, intermittently discharging said further capacitor upon the occurrence of said pre-selected signal to intermittently charge said first capacitor, and discharging said first capacitor during each period between the successively occurring intervals in which said first capacitor is being charged to effect the alternate charging and discharging of said first capacitor for causing an alternating current to flow through the ringer to energize the ringer.
References Cited (Backward Citations)
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Cited
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USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |