JPS5937558B2 - Power synchronized sine wave type X-ray tube voltage stabilization device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention automatically corrects the X-ray tube voltage in response to changes in the power supply voltage and X-ray tube current in an X-ray apparatus, so that a stable set tube voltage can always be obtained and the tube voltage can be adjusted. This invention relates to an X-ray tube voltage stabilizing device that can perform stepless and continuous operation.

There is a relationship of -Vn-1-T with the X-ray output ■■- of the X-ray device, where K is a constant, i is the tube current, and T is the exposure time, but when the power number n of the tube voltage V is 2 to 6 Therefore, even a slight change in the tube voltage V causes a large change in the X-ray output I.

Therefore, stabilizing the tube voltage is an important factor in stabilizing the X-ray output.

On the other hand, in most conventional X-ray apparatuses, the commercial power supply is directly connected to the high voltage generator, so that the tube voltage constantly fluctuates due to fluctuations in the power supply voltage.

Furthermore, the primary current of the high voltage transformer also changes due to the fluctuation of the tube current, which causes a voltage drop due to the power supply impedance and the internal impedance of the device, causing fluctuations in the tube voltage.

The above changes and fluctuations in tube current are due to the tube current settings.
This is due to the instability of the tube filament heating device.

Of these, the latter can be almost solved by increasing the stability of the heating device (excluding fluctuations due to deterioration of the tube filaments), but the former, that is, the setting of the tube current, can be solved by increasing the tube voltage depending on the imaging conditions of the X-ray device. As long as the tube current and the tube current are set individually, the difference in voltage drop due to their many combinations directly becomes a fluctuation in the tube voltage.

Of the voltage drops mentioned above, the amount due to the power supply impedance varies depending on the power supply situation of the location where the X-ray equipment is installed, so conventionally impedance matching is performed using a variable power resistor for adjusting the power supply impedance. , this method has limitations on the size of the power source impedance and requires a so-called high-quality power source.
The current situation is that the installation location of line equipment has to be considerably limited.

It is also quite difficult to set the resistance value accurately, and especially in devices with large currents, even a small difference in resistance causes a large difference in voltage drop, causing large fluctuations in the tube voltage.

An impedance control element that responds instantaneously and whose impedance changes continuously in order to prevent the tube voltage from being affected by the above-mentioned fluctuations in commercial power supply voltage, changes in voltage drop due to power supply impedance, and impedance within the equipment. (Semiconductor elements such as transistors, thyristors, and FETs) are used to absorb the effects of these changes.
Various line tube voltage stabilizing devices have been devised and used for some time.

However, most of these conventional stabilizing devices use the above-mentioned impedance control element to directly convert AC power to 0N-0.
This is a phase angle control method that uses FF.

This phase angle control method uses the nonlinear characteristics of impedance elements to control the power supplied to the load, so the output voltage waveform contains many harmonics. losses increase and reduce efficiency.

In addition, in order to prevent abnormal high voltage generated in the secondary winding of the high voltage transformer due to transient voltage (surge voltage) generated when the phase angle control is turned ON or OFF, an impedance is provided on the primary side to suppress the rise speed. Not only does the stabilizing device itself become large and complicated, but also the difference in the primary current of the high-voltage transformer due to the tube current, which varies widely depending on the setting as mentioned above, accumulates in the rise speed suppressing impedance. Since the energy differs, the power waveform may also change accordingly, but there is a drawback that the peak voltage value of the tube voltage and the applied voltage waveform cannot be accurately controlled.

In addition to the above, there is also a frequency conversion type X-ray tube voltage stabilization device using a controlled rectifier called a cycloconverter, which is conventionally used in some X-ray devices, but the output power waveform of this device is a rectangular wave. There are some disadvantages similar to those of the stabilizers described above, since they contain a lot of harmonics.

Although it is possible to make the output power waveform of this device a sine wave by using a filter, a large-capacity filter suitable for the output power is large and expensive, and the power loss in the power control section is large, resulting in a large amount of power. It is unsuitable as an X-ray tube voltage stabilizing device.

In view of the above-mentioned current situation, the present invention aims to eliminate the above-mentioned drawbacks caused by the conventional stabilizing device utilizing the nonlinear characteristics of the impedance control element, and to synchronize the transistor of the impedance control element with the commercial power supply cycle. By driving the high voltage transformer with a sine wave signal that has a stable amplitude with respect to its fluctuations, and controlling the power of the high voltage transformer using linear elements, the power waveform becomes a sine wave, increasing the efficiency of the transformer. With a simple and robust circuit configuration, the X-ray tube voltage can be smoothly and automatically corrected in response to changes in the power supply voltage and X-ray tube current, and a stable set tube voltage can always be obtained, and the tube voltage can be adjusted steplessly. This is related to the X-ray tube voltage stabilizing device to be obtained.

In other words, a sine wave generation circuit is provided that synchronizes with the commercial power supply and outputs a stabilized sine wave signal, and this sine wave output signal is used as an input to generate the primary circuit of a transformer with an X-ray tube connected to the secondary circuit. A linear power control element of a control circuit for controlling power is provided between a commercial power source and a primary winding of the transformer,
The impedance of this element is set to the primary or secondary of the transformer.
This invention relates to a power-synchronized sinusoidal X-ray tube voltage stabilizing device characterized in that control is performed using a sinusoidal deviation output between the voltage of the next circuit and a predetermined set voltage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of an X-ray tube voltage stabilizing device according to one embodiment, and FIG. 2 is an output waveform diagram of each block.

1 is a commercial power supply, and its voltage waveform is W in Figure 2 ■.

It is a sine wave like. 2 is a circuit that synchronizes with the commercial power supply 1 using a comparator amplifier with a pulse occupancy rate of 50%, and generates a rectangular wave (W, in Figure 2 ■) with a pulse occupancy rate of 50%; A circuit that generates a triangular wave such as W2 shown in Figure ■, 4 is a Miller integrator consisting of an operational amplifier that provides negative feedback from the output to the input via a capacitor. A circuit for converting the waveform into wave W'-3, and 5 is a phase shift circuit that synchronizes the sine wave of W'3 in Figure 2 (■) with the WO in Figure 2 (■), that is, commercial power supply synchronization, and W3 in Figure 2 (■). Match the phases so that

6 is the tube voltage setting circuit, and block 5 is the commercial power supply waveform W.

A voltage with a waveform that can be considered as a commercial power supply waveform with a stable amplitude and waveform that is phase-matched with that of Output to.

Block 7 is one of the high voltage transformers of the high voltage generator in 9.
A power control circuit whose power source is a commercial power source 8 having a peak value higher than the peak value of the next input voltage and whose input is the output signal S of the block 6, and a power control circuit driven by this control circuit.
It is composed of one or two power transistors, a tube voltage detection circuit, etc., and supplies the primary side power Ws of the high voltage transformer corresponding to the tube voltage setting value to the high voltage generator 9.

The power waveform of Ws is a sine wave synchronized with the commercial power supply synchronization, as shown in FIG. 2 (2).

The circuit configuration of this power control section 7 is shown in six embodiments in FIGS. 3 to 8, and its operation will be described later.

9 is a high voltage generator, which is the same as the conventional one including a high voltage transformer, a high voltage rectifier, a wire heating device, an operation panel, etc.

The above is an overview of the configuration and functions of the first embodiment of the apparatus of the present invention, which is comprised of blocks 1 to 9 in FIG.

Next, a second embodiment will be described in which ten broken line approximation circuits (dotted lines) are inserted in place of the four Miller integration circuits shown in FIG.

The broken line approximation circuit of No. 10 has a large number of diode and resistor networks between the input power and the output of the operational amplifier, and is configured so that the resistance decreases as the input increases.The gator decreases as the input amplitude increases, and the bias voltage By appropriately selecting the number of diodes and diodes, the triangular wave W2 shown in Figure 2 (■) can be converted into a sine wave W'3, and depending on the number of broken lines, the distortion rate as a sine wave can be reduced, and a good sine wave can be obtained. It becomes a generation circuit.

The other blocks are the same as those of the first embodiment.

Next, a third embodiment will be described in which blocks 11, 12, and 130, which are inserted by dashed lines in place of blocks 2 to 5 in FIG. 1, are used.

These three blocks are generally called PLL and are integrated into an IC phase-locked loop (Phase-Locked Loop).
11 is a phase comparator that constantly compares the signal Wo input from the commercial power supply 1 with the output signal W3 of the voltage controlled oscillator VCO of 13, and calculates the detected phase error voltage E.
x determines the response characteristics and removes unnecessary noise using 12 loop filters, and inputs it as the oscillation control signal So to 13 blocks, where the sine wave output signal W3 phase-synchronized with the input signal WO is oscillated. and is input to the tube voltage setting circuit 6, and thereafter operates in the same manner as the first and second embodiment devices.

Compared to the first and second embodiments, this third embodiment has a simpler circuit configuration, is integrated into an IC as described above, and has fewer passive elements (it has excellent stability).

The above three embodiment devices form the basis of the present invention, and the circuit configurations of each block except for 7 belong to the public knowledge, so although not shown in the drawings, as described above, the power amplifying section 1 is illustrated in FIGS. 3 to 8. An example of the circuit configuration will be described.

The block indicated by the 6,8°90 dotted line in Fig. 3 is the same as Fig. 1, and 7A is the first embodiment circuit of the power amplification section, and stepless setting is made by sliding contact 6C of the tube voltage setting device 6. The resulting voltage signal S (sine wave in Figure 2) is passed through an amplifier AI and a half-wave rectifier D.
1. The signal is input to the (± terminal) of the comparator amplifier A3 via a full-wave linear detection circuit consisting of a negative feedback resistor R1 and an amplifier A2.

The base current of the power transistor Trl is controlled by this sine wave signal, the impedance between the collector and emitter changes, and the power from the commercial power supply 8 is passed through the full-wave rectifier D3 to the primary winding of the high voltage transformer T1. It is supplied as Ws in Figure 2 (■).

There is a transformer T2 connected in parallel to the primary winding of this high voltage transformer T1, and a voltage detection circuit V, D consisting of a full wave rectifier D2 and resistors R2 and R3 is provided.
The output is input to the (→ terminal) of the comparison amplifier A3, and
Its output controls the impedance of the power transistor Tr1 until the tube voltage of the ray tube X reaches a set value.

Therefore, the power supply voltage Q fluctuation of 8 does not affect the primary voltage Ep of the high voltage transformer T1.

Furthermore, due to changes in the tube current of the X-ray tube, the high voltage transformer T1
When the primary current Ip of T1 changes, the input voltage Ep of T1 changes.

This change is immediately detected from the voltage detection circuits V and D to the comparator amplifier A.
3, and the output of A3, that is, Tr
The base current of Trl changes and the potential difference between the collector and emitter of Trl is automatically controlled so that the primary voltage Ep of the high voltage transformer T1 always remains at the set voltage.

In other words, the tube voltage is automatically corrected for changes in the tube current so that the tube voltage set by the tube voltage setting device 6 is always obtained no matter what causes the tube current to change.

The above is an explanation of the operation of the X-ray tube voltage stabilizing device of the present invention using the first embodiment circuit of the power control section.

In the following description of the second to sixth embodiments of the power amplifying section 7A, differences from the first embodiment will be described, and explanation of the stabilizing operation will be omitted.

In Figure 4, two transistors are used as impedance control elements, a summing amplifier A5 and a tube voltage detection resistor R4.
JR5 is set to connect the output of the comparison amplifier to the transistor Tr.
2. FIG. 3 is a circuit diagram of a power control unit 7B that is input to both bases of Tr3 and controls power from a half-wave rectifier D4 for each half-wave.

In FIG. 5, a transformer T3 is used instead of the summing amplifier, and the voltage detection circuit V, D is replaced by a diode D5? Power control section 7C consisting of D6 and resistor and using two comparison amplifiers A6 and A70
FIG.

The above three types of power control units use an impedance control element to correct changes in the primary voltage of the high voltage transformer due to fluctuations in the power supply and changes in tube current. Since the influence of the voltage drop in the power control section, high voltage transformer, (7) 11 connection wire, and its primary and secondary windings on the X-ray tube voltage cannot be ignored, the voltage detection circuits V and D are set to high voltage. Two embodiments provided on the secondary side of a voltage transformer and one embodiment for detecting the primary current are shown in the sixth, seventh, and third embodiments.
This will be explained using Figure 8.

FIG. 6 shows that the power control section 7B (FIG. 4) is used to input the secondary voltage of the high voltage transformer to the differential amplifier A8, which is the output of the voltage detection circuit V, Ds, which consists of the transformer T4 and the resistor R6. ,1
This is a power control unit 7D that improves the stability of the control circuit system in conjunction with feedback with the voltage detection circuits V and D of the next example.

Similarly to the above, FIG. 1 shows that the comparator amplifier A4 of the power control section 7B of FIG.
This is a circuit configuration of a power control unit IE that feeds back the output of s.

FIG. 8 shows that a non-inductive resistor R7 is inserted into the primary line of the high voltage transformer T1 in the power control section 7B of FIG. Corrects changes in the primary current by adding
This is an example circuit of the power control section 7F, which is another requirement of the present invention, and particularly improves the stability of the voltage of a large-capacity X-ray tube.

As explained above, the tube voltage stabilizing device which combines the six power control units shown in Figs. 3 to 8 into block 1 in Fig. This is a sinusoidal tube voltage stabilizer configured to compensate for voltage drop fluctuations such as power supply impedance and internal impedance due to changes and other fluctuations with the impedance of an impedance control element, and the circuit configuration is limited to the above embodiment. It's not something you can do.

Since the present invention is configured as described above, the X-ray tube voltage can be eliminated by using a transistor as a linear power control element, synchronizing it with a commercial power supply, and controlling it with a sine wave signal having a stable amplitude. In addition to continuously setting the X-ray tube voltage in 5 steps, the tube voltage is immediately and automatically corrected for fluctuations in the power supply and tube current, and the X-ray tube voltage is always kept at the set voltage and the X-ray output is stabilized. In addition to having the great effect of improving diagnostic performance, the power waveform applied to the high voltage transformer is a sine wave, which not only increases the efficiency of the transformer, but also allows direct use of commercial power as a power source. It eliminates the need for large impedance elements for suppressing surge voltage and current that were conventionally attached to general stabilizing devices, and the rectification and smoothing circuits used in the cycloconverter method described above. It will be highly reliable.

Furthermore, since there are no harmonics with large energy that are generated during phase angle control or square wave control, there are no interference radio waves caused by electromagnetic induction from the transformer being used or the electrical circuit through which large currents flow, so it is possible to The present invention has provided an excellent X-ray tube voltage stabilizing device that has significant effects such as eliminating the need for measures to prevent interference with medical equipment and the like.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing three embodiments of the X-ray tube voltage stabilizing device of this invention, Fig. 2 is an output waveform diagram of each block, and Figs. Example circuit diagram of the power control section of the tube voltage stabilizing device (for standard capacity X-ray equipment), No. 6. γ, FIG. 8 is a circuit diagram of an embodiment of a power control section mainly for a large-capacity X-ray apparatus. Wo...Commercial power wave, Wl...Square wave, W2...Triangle, W'3...Sine wave, W3...Commercial Power synchronized sine wave, Ws...
...Control power wave, S...Tube voltage setting value signal (sine wave), Ex...Phase error voltage, So...
...Oscillation control signal, T1...High voltage transformer, E
p...Primary voltage above, Ip...Primary current above, T2...Primary voltage detection transformer, V
, D... (primary) voltage detection circuit, 6c...
・・Tube voltage setting device moving contact, A1~A,・・・・・・I
C amplifier, Trl to Tr5... Power transistor (impedance control element), D1 to D8...
...Diode, T3...Setting signal transformer, V
, Ds... (secondary) voltage detection circuit, R7...
...Non-inductive resistance for detecting voltage drop of primary current.

Claims (1)

[Claims] 1. A sine wave generating circuit is provided which synchronizes with a commercial power source and outputs a stabilized sine wave signal, and an X-ray tube is connected to a secondary circuit using this sine wave output signal as input. A linear power control element of a control circuit for controlling the primary power of the transformer is provided between the commercial power supply and the primary winding of the transformer, and the impedance of this element is set to the primary or secondary circuit of the transformer. A power synchronized sine wave type % type which is characterized in that it is controlled by a sine wave deviation output between the voltage of the voltage and a predetermined set voltage. 2. A power-synchronized sine wave type X-ray tube voltage stabilizing device according to claim 1, further comprising a sine wave generating circuit configured to convert the waveform into a sine wave generator. 3. Power-synchronized sinusoidal X-ray tube voltage according to claim 1, which is provided with a sine wave generation circuit that converts a triangular wave generated in synchronization with a commercial power source into a sine wave using a broken line approximation circuit. Stabilizer. 4. The power-synchronized sine wave type according to claim 1, wherein the sine wave generating circuit is a phase-locked loop consisting of a voltage-controlled oscillator that generates a sine wave in synchronization with a commercial power source, a phase comparator, and a loop filter. Equation % 5 A sine wave generating circuit is provided that synchronizes with the commercial power supply and outputs a stabilized sine wave signal, and this sine wave output signal is used as input to generate one of the transformers with an X-ray tube connected to the secondary circuit. A linear power control element of the control circuit is provided between the commercial power source and the primary winding of the transformer, and the impedance of this element is adjusted to the voltage of the primary circuit of the transformer and a predetermined set voltage. 1. A power supply synchronized sinusoidal X-ray tube voltage stabilizing device, characterized in that control is performed by outputting a sinusoidal wave deviation from an added voltage obtained by adding a voltage drop due to a current in a subsequent circuit.