JPH0520880B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an X-ray device.

When using an X-ray tube in an X-ray device for the first time or after it has been left unused for a long time, if a high voltage close to the rated voltage is suddenly applied, the vacuum pressure inside the tube may drop, impurity gas may be generated, etc. This may reduce the withstand voltage and shorten the life of the X-ray tube, or even destroy the tube.To prevent this, the tube voltage must be gradually raised to the rated value over time. It is a well-known fact that a procedure called aging (also called aging) is taken.

Conventionally, this warm-up has generally been carried out manually by the operator, but it is necessary to perform the warm-up every day. Not only is it a great waste of time to have to manipulate the device for this purpose, but there is also the risk of destroying the X-ray tube due to incorrect operation. The present invention was made in view of the above circumstances, and
An oscillator that generates clock pulses, a counter that is activated by a start command and counts the clock pulses, a D/A converter that converts a predetermined bit output of the count value of this counter into an analog signal, and a movable element that adjusts the output voltage. The output of this voltage regulator is taken as input, and the voltage is boosted to
a high voltage generator that generates a tube voltage to be applied to the line tube; a differential amplifier that compares a detected voltage of the applied tube voltage with the output of the D/A converter as a reference and generates a difference output; and the differential amplifier Drive according to the output,
The voltage regulator is equipped with a servo motor that operates a movable element of the voltage regulator to vary the output voltage, and the clock pulses are counted by a counter and a predetermined bit output of the counted value is converted into analog, so that the level is adjusted every predetermined period. By obtaining a changing reference voltage and automatically adjusting the output voltage of the voltage regulator so that the tube voltage corresponds to this reference voltage,
An object of the present invention is to provide an X-ray apparatus that saves the operator's time and effort associated with warm-up operations, eliminates the risk of erroneous operation, and enables warm-up of an X-ray tube under desired warm-up conditions. shall be.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the apparatus of the present invention which is applied when performing warm-up by applying a continuous voltage.

In the drawing, numeral 1 is an oscillator that generates clock pulses, and numeral 2 is an 8-bit counter, for example, which is preset with a preset input value (A ₁ -A ₃ ) at the time of start, and which cumulatively counts the clock pulses based on this preset value. The output terminal of the 8th bit, which is the most significant digit of this counter 2, has the first
The excitation coil Ry ₁ -L of the relay Ry ₁ is connected and is energized when the 8th bit becomes "1". 3 is a D/A converter that converts a digital value into an analog value, converts the output of the counter 2 into an analog value (voltage), and supplies this as a reference voltage to the differential amplifier during warm-up. . Also, VR is D/A converter 3
A variable resistor 5 is provided on the output side of the voltage regulator for adjusting the voltage, and 5 is a variable resistor for dividing the voltage between the negative potential -Vcc and ground to generate a reference voltage for adjusting the output of the voltage regulator at the end of warm-up. A reference voltage setting device using a resistor, Ry ₂ -A, is a switching contact of the second relay, and its normally closed side is connected to the reference voltage setting device 5, and its normally open side is connected to the output side of the variable resistor VR ₁ . The switching contact Ry ₂ -A of the second relay selects one of the two relays, and the reference voltage is supplied to the inverting side of the differential amplifier 4 via the input resistor R ₁ . 6 is a voltage regulator such as a slider, and its output is applied to the high voltage generator 7 via the normally open contact Ry ₂ -B of the second relay. The high voltage generator 7 is provided with a step-up transformer TR, diodes D ₁ to _{D 4} forming a bridge rectifier circuit, and capacitors C ₁ and C ₂ for smoothing the rectified output. The high voltage obtained is applied to the X-ray tube 8 as a tube voltage. Moreover, a series resistance R ₃ ~
R ₆ is connected, and the output divided by resistors R ₃ and R ₄ is supplied to the differential amplifier 4 via the input resistor R ₂ as the tube voltage detection power. The difference between the reference voltages is output. Reference numeral 9 denotes an output voltage control servo motor 9 which is driven in forward and reverse directions by the output of the differential amplifier 4 and moves a brush, which is a movable element for adjusting the output of the voltage regulator 5. Ry ₁ -S is a normally open contact of the first relay, Ry ₂ -C is a normally open contact of the second relay,
Ry ₂ -L is an excitation coil of the second relay, and these are connected in series between the DC positive potential Vcc and the ground point. Further, SW ₁ is a warm-up start switch, and this warm-up start switch SW ₁ is connected in parallel to the normally open contact Ry ₂ -C of the second relay, and Ry ₂ -C is the self-holding switch of the second relay. A circuit is formed, and the first relay Ry ₁ maintains self-holding until it is activated by the output of the counter 2. Ry ₂ -D is a normally open contact of the second relay and is used as a switch for starting the counter 2.

Next, the operation of this apparatus having the above configuration will be explained.

Now, with this circuit configuration, see Figure 3 for the operation when a warm-up specification is required to reach the rated voltage through four voltage levels V ₀ to V ₃ at predetermined time intervals as shown in Figure 2. I will explain while doing so. For the sake of simplicity, the following explanation will be based on the assumption that the counter is composed of 8 bits, of which the 2nd to 4th bits counted from the most significant are subjected to D/A conversion.

When warm-up switch SW ₁ is operated
Since Ry ₁ -S is closed, the excitation coil Ry ₂ -L of the second relay is excited. Therefore, Ry ₂ -C closes and becomes self-holding state, and Ry ₂ -B, Ry ₂ -D
When the counter 2 is closed, the counter 2 is preset to a preset value "00000010" and starts counting the clock pulses output from the oscillator 1. Among the count outputs, B ₅ , B ₆ , and B ₇ are D/A converted and converted into voltage.

That is, in the first stage, in order to obtain a tube voltage of V ₀ , the reference voltage is 4/8v _O (v _p is a certain constant voltage) as shown in Fig. 3, and then D/
Assuming that the A conversion output corresponds to the count value "0010" of the counter 2 (the right side is the most significant bit), the reference voltage 4/ _8vp is obtained by setting the preset value of the counter 2 to "00000010". During this time, the differential amplifier receives this reference voltage via Ry ₂ -A, detects and outputs the difference between this and the feedback voltage, and supplies the detected voltage to the servo motor 9. As a result, the voltage regulator 6 and the brush 6a are rotated in the normal direction, and the voltage gradually increases (for example, in 2 to 3 seconds). The output voltage of this voltage regulator 6 is input to a high voltage generator 7, boosted, rectified and smoothed, and then applied to an X-ray tube 8.
The high voltage divided output (due to R ₃ and R ₄ ) is supplied to the differential amplifier 4 as a feedback voltage. When these voltages match, the servo motor stops. (Tube voltage V ₀ ) The output voltage of the voltage regulator 6 is
D/A the upper 3 bits of the counted value excluding the highest
Because it is converted and used, the counting time for the lower 4 bits, that is, 16 from "0" to "15" count equivalent.
The counting time of the clock becomes the holding time of the tube voltage in the special stage. Next, counting progresses for 16 clocks from the time of the first stage and reaches the "16" count (17th clock), when the upper bit of counter 2 changes from "0010" to "1010" as shown in Figure 3. Assuming that the analog conversion output of this count value by the D/A converter 3 corresponds to 5/8v _p which determines the second stage tube voltage V ₁ , the reference voltage 5/8v _p is obtained. This reference voltage 5/8v _p
The difference between the voltage and the feedback voltage is applied to the servo motor 9, and the servo motor 9 rotates. This moves the brush 6a of the voltage regulator 6, and controls the input voltage of the high voltage generator 7 to generate the high voltage _V1 so that the tube voltage reaches the second stage _V1 .

Similarly, when another 16 clocks have passed since the second stage and the count reaches "32", another 16 clocks have passed and the count reaches "48". When the upper bit of the count value of the counter 2 changes, the reference voltage changes as shown in FIG. 3, and the tube voltage rises to a predetermined value accordingly. Also, when the count value changes to "64" count, the B ₈ bit, which is the most significant bit of counter 2, becomes "1", so
At this output, the excitation coil Ry ₂ -L of the first relay
energize and operate. As a result, the self-holding of the second relay is released and deenergized, Ry ₂ -B is opened and the power supply to the high voltage generator 7 is stopped, and the switching contact Ry ₂ -A of the second relay is normally closed. The reference voltage value (having a potential opposite to that of the output of the D/A converter) output from the reference voltage setter 5 after being switched to the closed side is applied to the differential amplifier 4 as a reference voltage. Therefore, the differential amplifier 4 generates an output corresponding to this input potential to reverse the servo motor 9, so that the brush 6a of the voltage regulator 6 is moved to the lowest voltage side. Therefore, a micro switch or the like is used to detect the lowest position and stop the servo motor.

In this case, for example, if the period of the clock pulse of the oscillator 1 is 10 seconds, the tube voltage will be switched every 160 seconds. Therefore, the warm-up conditions can be varied by appropriately changing the period of the output clock pulse of the oscillator 1, the number of lower bits of the counter 2, the number of bits and digits to be converted into D/A, and the step of the analog conversion value. It is possible to set it to .

Furthermore, by increasing the number of bits for D/A conversion, it is possible to generate a reference voltage in as fine a step as necessary, and for example, it is also possible to increase the tube voltage along a substantially linear curve as shown in FIG.

In addition, by applying a certain voltage V to the output of the D/A converter 3 as shown in Fig. 5 using an operational amplifier OP, etc., and adding it, a counter without a preset input can be used to generate the output voltage as shown in Figs. 2 and 4. It is also possible to warm up the curve.

Further, as shown in FIG. 6, the counter 2 is provided with a buffer BF for temporarily storing the output of the counter 2, and a gate signal SG is provided to control the buffer BF.
By controlling this buffer BF to control the transfer of the output of the counter 2 and supplying it to the D/A converter 3, it is also possible to warm up the curve as shown in FIG.

If more complicated step time intervals or warm-up of a voltage rise curve are required, a memory M is provided between the counter 2 and the D/A converter 3 as shown in FIG. Store a digital quantity equivalent to the reference voltage,
By sequentially reading digital quantities from this memory M using the count value of the counter 2 as an address, it is possible to warm up a voltage curve of any shape.

In addition, in the above embodiment, the output of the high voltage side of the high voltage generator 7 was fed back to the differential amplifier 4, but since there is a nearly linear correspondence between the output of the voltage regulator 6 and the X-ray applied voltage, the voltage can be adjusted. The output of the device 6 can also be controlled by feedback.

If a warm-up condition in which voltage is applied intermittently as shown in Figure 9 is required, the output of the voltage regulator 6 can be rectified and smoothed by a rectifier and smoothing circuit RF as shown in Figure 10.
Feedback is performed after smoothing, and a third relay common contact Ry _3a is provided between the output of the voltage regulator 6 and the high voltage generator 7, and the third relay is turned on and off by the output from the counter 2, for example. The input of the high voltage generator 7 may be turned on and off at predetermined intervals. In the example of Figure 3, counter 2
If the normally open contact Ry _3a of the third relay is turned ON when the fourth output bit _B4 is "1", warm-up as shown in FIG. 9 can be performed. Similarly, a sequence may be created to control the third relay Ry ₃ according to the necessary warm-up conditions.

An oscillator that generates clock pulses in this manner, a counter that operates in response to a start command and counts the clock pulses output from this oscillator, and a D/A converter that converts a predetermined bit output of the count value of this counter into a D/A converter. a voltage regulator having a movable element that adjusts the output voltage; a high voltage generator that receives the output of the voltage regulator as an input and boosts the voltage to generate a tube voltage to be applied to the X-ray tube; and the D/A converter. The detected voltage corresponding to the tube voltage is compared with the output of the voltage regulator, and the difference output and the generated differential amplifier are driven according to the differential amplifier output, and the movable element of the voltage regulator is operated. It is equipped with a servo motor that varies the output voltage, counts clock pulses and a counter, and converts a predetermined bit output of the counted value to D/A to obtain a reference voltage that changes every predetermined period, and uses this reference voltage and a high voltage. This voltage regulator generates a voltage that can obtain the tube voltage corresponding to the reference voltage by comparing the difference output and driving the servo motor that drives and controls the movable element of the voltage regulator. /A By setting the digit range of the count value to be converted, the magnitude of the analog conversion amount relative to the level control amount of the tube voltage, and the period of the clock pulse, etc., it is possible to sequentially change the amount by a predetermined amount at a predetermined period. The tube voltage can be warmed up by increasing the tube voltage, and this can be done automatically.Since it is automated, there is no risk of erroneous operation.Furthermore, there is no need to perform any calculations on the counter output, or perform any calculations on the counter output. It has excellent features such as being able to perform automatic warm-up corresponding to arbitrary warm-up conditions by sequentially reading out digital values from pre-stored memory and converting them to a reference voltage. An X-ray device can be provided.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an example of the implementation of the X-ray apparatus of the present invention, Fig. 2 is a diagram for explaining the relationship between the number of counts (or time) and applied voltage by the apparatus of Fig. 1, and Fig. 3. is a diagram for explaining the correspondence between the count value of the counter in FIG. 1 and the reference voltage and tube voltage at that time; FIGS. 4, 7, and 9 are diagrams showing examples of warm-up conditions; Figure 5, Figure 6,
FIGS. 8 and 10 are partial circuit diagrams showing configurations that satisfy the conditions shown in FIGS. 4, 7, and 9. 1...Oscillator, 2...Counter, 3...D/A
Converter, 4...Differential amplifier, 5...Reference voltage setter, 6...Voltage regulator, 7...High voltage generator,
8...X-ray tube, 9...servo motor, BF...buffer, M...memory.

Claims (1)

[Scope of Claims] 1. An oscillator that generates clock pulses, a counter that is activated by a start command and counts the clock pulses from a preset value that determines the tube voltage in the first stage, and a predetermined bit output of the count value of this counter. A D/A converter that converts it into an analog signal and outputs it as a reference voltage, a voltage regulator that adjusts the output voltage, and the output of this voltage regulator as input,
A high voltage generator that boosts the voltage to generate a tube voltage to be applied to the X-ray tube, and a differential amplifier that compares the detected voltage of the applied voltage with the output of the D/A converter as a reference and generates a difference output. and a control section that controls the voltage regulator to vary the output voltage according to the output of the differential amplifier, counts the clock pulses with a counter and extracts a predetermined bit output from the counted value, An X-ray apparatus characterized in that a reference voltage whose level changes every predetermined cycle is obtained by analog conversion, and the output voltage of the voltage regulator is automatically adjusted so that the tube voltage corresponds to this reference voltage. 2. The X-ray apparatus according to claim 1, wherein a predetermined voltage is added to the output of the D/A converter to obtain a reference voltage. 3. The X-ray apparatus according to claim 1, wherein the counter is provided with a buffer for temporarily storing the counted value of the counter, and the counted value is provided to a D/A converter via this buffer. . 4. An oscillator that generates clock pulses, a counter that operates in response to a startup command and counts the clock pulses, and a memory that stores digital values corresponding to a plurality of reference voltages and reads out stored data using the counted value of the counter as an address. A D/A converter converts the read data of the memory into an analog signal and outputs it as a reference voltage, a voltage regulator adjusts the output voltage, and the output of this voltage regulator is input and boosted to the X-ray tube. a high voltage generator that generates a tube voltage to be applied to the D/A converter; a differential amplifier that compares the detected voltage of the applied voltage with the output of the D/A converter as a reference and generates a difference output; and a control section that controls the voltage regulator to vary the output voltage, and counts the clock pulses with a counter, extracts a predetermined bit from the counted value, and reads the address corresponding to the value. A reference voltage whose level changes at predetermined intervals is obtained by reading out the memory contents and analog-converting the same, and the output voltage of the voltage regulator is automatically adjusted so that the tube voltage corresponds to this reference voltage. An X-ray device featuring: