X-ray diagnostic apparatus

Claim 2

X-ray diagnostic apparatus, particularly adapted for tomography with variable focal distances, including : an X-ray source ; a housing ; a column for carrying said X-ray source comprising : a lower portion mounted on said housing for pivoting about a horizontal axis and an upper portion carrying said X-ray source at its upper end, said upper portion being assembled with said lower one for longitudinal displacements in relation thereto, both said portions having parallel longitudinal axes perpendicular to said horizontal one ; a first electric motor having a stator fixed to said housing and a rotor mechanically coupled to said lower portion for controlling said pivoting thereof about said horizontal axis, a second electric motor having a stator fixed to said lower portion and a rotor mechanically coupled to said upper portion for controlling said longitudinal displacements ; means for delivering an electrical signal which is a function of the angle of inclination gamma of said column ; electronic analogue circuit means fed by said signal for controlling said second motor in dependence of said angle gamma , whereby the motion of said X-ray source during the pivoting of said column is made to be substantially rectilinear.

Claim 3

Apparatus as claimed in claim 1, further comprising : a second potentiometer having a slider mechanically coupled to said rotor of said second motor for delivering a second voltage proportional to the position of said upper portion in relation to said lower one ; and a variable direcT voltage source for delivering a third voltage proportional to the selected focal distance R ; and wherein said electrical signal delivering means comprises a first potentiometer having a slider mechanically coupled to the rotor of said first motor for delivering a first voltage proportional to said angle gamma ; and wherein said electronic circuit means comprises : a squaring circuit for delivering a signal proportional to the half of the square of said first voltage applied to its input ; a multiplier circuit for delivering a signal proportional to the product of said third voltage with said half-square of said first voltage i.e. proportional to R gamma 2/2 ; and a differential amplifier for delivering an error signal proportional to the difference between said product signal and said second voltage whereby controlling said second motor.

Claim 4

Apparatus as claimed in claim 1, further comprising : a second potentiometer having a slider mechanically coupled to said rotor of said second motor for delivering a second voltage proportional to the position of said upper portion in relation to said lower one ; and a variable direct voltage source for delivering a third voltage proportional to the selected focal distance R ; and wherein said electrical signal delivering means comprises : a resolver fed by a constant amplitude alternating current, having a rotor mecahnically coupled to said rotor of said first motor for delivering an alternating voltage with an amplitude proportional to the cosine of said angle gamma ; and amplitude detector means for rectifying said alternating voltage and for delivering a fourth direct voltage whose level is proportional to cosine gamma ; and wherein said electronic circuit means comprises : an electronic analogue divider circuit for delivering a fifth voltage proportional to the ratio of said third to said fourth voltages i.e. proportional to R/cos gamma ; an electronic subtracting circuit for delivering a sixth voltage proportional to the difference between said ratio voltage and said third voltage i.e. proportional to R/cos gamma - R ; and a differential amplifier for delivering an error signal proportional to the difference between said sixth and said second voltages whereby controlling said second motor.

Claim 5

Apparatus as claimed in claim 1, further comprising : a second potentiometer having a slider mechanically coupled to said rotor of said second motor for delivering a second voltage proportional to the position of said upper portion in relation to said lower one ; and a variable direct voltage source for delivering a third voltage proportional to the selected focal distance R ; and wherein said electrical signal delivering means comprises : a potentiometer of the sine-cosine type having a slider coupled to said rotor of said first motor for delivering a fourth voltage whose level is proportional to the cosine of said angle gamma ; and wherein said electronic circuit means comprises : an electronic analogue divider circuit for delivering a fifth voltage proportional to the ratio of said third to said fourth voltages i.e. proportional to R/cos gamma ; an electronic substracting circuit for delivering a sixth voltage proportional to the difference between said ratio voltage and said third voltage i.e. proportional to R/cos gamma - R ; and a differential amplifier for delivering an error signal proportional to the difference between said sixth and said second voltages whereby controlling said second motor.