JP4231238B2 - High voltage generator and X-ray generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray generator used in, for example, industrial nondestructive inspection and medical fields, and a high voltage generator applied to the X-ray generator, and particularly has a wide voltage control range and is extremely stable. The present invention relates to a high voltage generator and an X-ray generator capable of performing voltage control, and further to an X-ray generator capable of performing a very stable tube current control with a wide tube current control range.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an X-ray generator that uses an X-ray tube, for example, in the fields of industrial nondestructive inspection and medicine, an X-ray is applied by applying a high voltage between the anode and the cathode of the X-ray tube Is generated.
[0003]
In this case, in order to obtain a high voltage, the voltage is boosted only with a step-up transformer, or boosted together with a Cockcroft-Walton type booster circuit (hereinafter referred to as CW circuit).
[0004]
FIG. 9 is a block circuit diagram showing a schematic configuration example of this type of conventional step-up transformer only type X-ray generator.
[0005]
In FIG. 9, a DC voltage A is generated from a commercial AC power source by a DC power source 101, converted into a pulse voltage by switches 102 and 103 formed of transistors, and boosted by a step-up transformer 104.
[0006]
The pulsed high voltage after the boosting becomes a DC high voltage in the rectifying / smoothing circuit 105 and is applied to the X-ray tube 106 to generate X-rays therefrom.
[0007]
The tube voltage of the X-ray tube 106 is fed back to the voltage control unit 107.
[0008]
The voltage control unit 107 controls the tube voltage to match the value set by the voltage setting unit 108 by changing the pulse width of the switching pulses C1 and C2 (generated alternately).
[0009]
The tube current flowing through the X-ray tube 106 is controlled by changing the voltage applied to the filament of the cathode 109 and changing the amount of thermionic electrons in a similar circuit.
[0010]
On the other hand, in order to increase the transmission ability of X-rays, it is necessary to increase the tube voltage of the X-ray tube 106 to generate high-energy X-rays. If it is too high, the contrast of the transmitted image is undesirably lowered.
[0011]
Therefore, it is necessary to select a tube voltage suitable for the subject.
[0012]
Further, although the amount of X-rays varies depending on the magnitude of the tube current of the X-ray tube 106, it is necessary to select a tube current suitable for the subject.
[0013]
[Problems to be solved by the invention]
However, the conventional X-ray generator as described above has a problem that the control range of the tube voltage is narrow.
[0014]
That is, in order to increase the efficiency of boosting, the switching of the switches 102 and 103 is performed at a high frequency of about 80 KHZ, so the period is as short as 13 μS and the pulse width is short on the low tube voltage side. This is because it becomes too much and accuracy is not obtained.
[0015]
In order to solve this problem, a method has been proposed in which the voltage controller 107 further controls the DC power supply 101 to change the DC voltage A.
[0016]
However, the response speed of the tube voltage control of the X-ray tube 106 becomes slow, and there is a new problem that stable and accurate control cannot be performed against disturbance.
[0017]
Similarly, there is a problem that the control range is narrow with respect to the tube current. Similarly, when this is attempted to be solved, there is a new problem that stable and accurate control cannot be performed.
[0018]
An object of the present invention is to provide a high voltage generator and an X-ray generator capable of performing a very stable voltage control with a wide voltage control range.
[0019]
Furthermore, an object of the present invention is to provide an X-ray generator that has a wide tube current control range and can perform extremely stable tube current control.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, a high voltage generator according to a first aspect of the present invention performs a switching operation with a DC power source that outputs a DC voltage and an output from the DC power source as inputs. Output a pulse waveform with a predetermined frequency A first switch and from the first switch Pulse waveform Output as input The pulse waveform is converted into a pulse shape with a low peak and a wide width. A low-pass filter; at least one second switch for performing a switching operation with an output from the low-pass filter as an input; and a boosting unit for boosting and outputting a high voltage with an output from the second switch as an input; On the first switch Above A first switching pulse is applied at a predetermined frequency and with a first pulse width, and the second switch is synchronized with the first switching pulse. At the predetermined frequency or 1 / n (n is an integer) of the predetermined frequency Voltage control means for controlling a voltage output from the boosting means by applying a second switching pulse with a second pulse width and changing the first pulse width and the second pulse width; I have.
[0021]
Therefore, in the high voltage generator according to the first aspect of the present invention, the first switch that conducts the DC voltage at the predetermined frequency with the first pulse width is passed through the low-pass filter to pass through the second pulse. Passing through at least one second switch that conducts in synchronism with the first switch in width, boosts the pulsating voltage obtained here to approximately the product of the first pulse width and the second pulse width By controlling the voltage output from the boosting means by obtaining a proportional high voltage and changing the first pulse width and the second pulse width, the voltage control range is wide and extremely stable voltage control is possible. Can be done.
[0022]
According to a second aspect of the present invention, there is provided an X-ray generator of the invention corresponding to the first aspect of the invention, wherein an X-ray tube to which a voltage output from the boosting means is applied is added. .
[0023]
Therefore, in the X-ray generator of the invention corresponding to Claim 2, by applying the voltage output from the booster circuit to the X-ray tube, the tube is formed in the same manner as in the case of the invention corresponding to Claim 1 above. The voltage control range is wide, and extremely stable voltage control can be performed.
[0024]
The X-ray generator of the invention corresponding to claim 3 performs a switching operation with a DC power source that outputs a DC voltage and an output from the DC power source as inputs. Output a pulse waveform with a predetermined frequency A first switch and from the first switch Pulse waveform Output as input The pulse waveform is converted into a pulse shape with a low peak and a wide width. A low-pass filter; at least one second switch that performs a switching operation using an output from the low-pass filter as an input; an X-ray tube having a cathode as a heat source to which an output from the second switch is applied; 1 switch Above A first switching pulse is applied at a predetermined frequency and with a first pulse width, and the second switch is synchronized with the first switching pulse. At the predetermined frequency or 1 / n (n is an integer) of the predetermined frequency By applying a second switching pulse with a second pulse width and changing the first pulse width and the second pulse width, the temperature of the heat source of the X-ray tube is changed, and the X-ray tube is Current control means for controlling the flowing tube current.
[0025]
Therefore, in the X-ray generator of the invention corresponding to claim 3, the first switch that conducts the DC voltage at the predetermined frequency with the first pulse width is passed through the low-pass filter, and the second pulse is passed through. An effective voltage pulsating flow that is approximately proportional to the product of the first pulse width and the second pulse width obtained through at least one second switch that is conductive in synchronism with the first switch in width. By applying a voltage to the heat source (cathode filament) of the X-ray tube and changing the first pulse width and the second pulse width, the temperature of the X-ray tube heat source is changed (thermoelectrons are changed). By controlling the tube current flowing through the X-ray tube, the tube current control range is wide, and extremely stable tube current control can be performed.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0027]
(First embodiment)
FIG. 1 is a block circuit diagram showing a schematic configuration example of a high voltage generator according to the present embodiment and an X-ray generator to which the high voltage generator is applied.
[0028]
In the block circuit diagram of FIG. 1, the going and returning of current (+ side and − side) are regarded as equivalent and drawn as a set.
[0029]
In FIG. 1, a DC power source 1 is composed of a rectifier (diode), a choke coil, a capacitor, and the like, and rectifies and smoothes the output from a commercial AC power source to generate and output a DC voltage.
[0030]
The output from the DC power supply 1 is input to a switch 2 (corresponding to a first switch) made of a switching transistor, and is converted into a pulse voltage having a frequency ν by a switching operation.
[0031]
The output from the switch 2 is input to a low-pass filter 3 composed of a choke coil, a capacitor, etc., and the high-frequency component is removed, thereby converting the pulse-like voltage into a pulse-like voltage having a low peak and a wide width.
[0032]
The output from the low-pass filter 3 is input in parallel to a switch 4 and a switch 5 (corresponding to a second switch) each consisting of a switching transistor.
[0033]
Here, the pulse voltage from the low-pass filter 3 is alternately switched by the switch 4 and the switch 5 at the frequency ν / 2 in synchronization with the switching operation of the switch 2.
[0034]
In the switches 4 and 5, the negative side is switched.
[0035]
Outputs from the switches 4 and 5 are respectively input to a booster circuit 6 composed of a transformer.
[0036]
The + side of the output from each switch 4 and switch 5 is connected to the midpoint of the primary winding of the transformer, and the − side of the output from each switch 4 and switch 5 is one end of the primary winding of the transformer. The other is connected to the other end of the primary winding of the transformer.
[0037]
Thereby, in the booster circuit 6, the directions of the currents flowing through the primary windings of the transformer due to the conduction of the switches 4 and 5 are opposite to each other, and the output from the booster circuit 6 is boosted to a high voltage. , A pulsating voltage in which a + side pulse and a − side pulse appear alternately at a frequency ν / 2,
The output from the booster circuit 6 is input to the rectifying / smoothing circuit 7, converted into a DC high voltage, and applied to the X-ray tube 9.
[0038]
The voltage control unit 10 gives signals to the switch 2, the switch 4, and the switch 5 to make them conductive.
[0039]
That is, the switching pulse A (corresponding to the first switching pulse) is given to the switch 2 at the frequency ν (about 80 KHZ) and with the first pulse width.
[0040]
The switch 2 becomes conductive during this pulse width.
[0041]
Further, in synchronization with the switching pulse A, the switching pulse C1 and the switching pulse C2 (corresponding to the second switching pulse) are alternated with each other at the frequency ν / 2 (that is, every other) with the second pulse width. ) And are given to the switch 4 and the switch 5, respectively.
[0042]
By changing the first pulse width or the second pulse width, the output from the booster circuit 6 changes.
[0043]
The output from the booster circuit 6 is also input to the voltage measurement unit 8, and the tube voltage of the X-ray tube 9 measured here is input to the voltage control unit 10.
[0044]
Here, the voltage measuring unit 8 divides the tube voltage by a resistance to obtain a measured value.
[0045]
The voltage setting unit 11 inputs the set tube voltage to the voltage control unit 10.
[0046]
The voltage controller 10 controls the voltage so that the measured value of the tube voltage output from the booster circuit 6 matches the set value by changing the first pulse width and the second pulse width.
[0047]
Next, operations of the high voltage generator and the X-ray generator according to the present embodiment configured as described above will be described with reference to FIG.
[0048]
FIG. 2 is a time chart showing a change in voltage of each part over time.
[0049]
In FIG. 1, a switching pulse A (point A) of the switch 2 is a rectangular pulse having a frequency ν and a first pulse width WA, and the switch 2 becomes conductive during the first pulse width WA.
[0050]
The output from the switch 2 has almost the same voltage waveform as that at point A, but the output from the low-pass filter 3 (point B) is converted into a pulse shape with a low peak and a wide pulse waveform.
[0051]
This peak value Vp is substantially proportional to the first pulse width WA.
[0052]
A switching pulse C1 (point C1) of the switch 4 is a rectangular pulse having a frequency ν / 2 and a second pulse width WC, and is synchronized with the switching pulse A.
[0053]
Similarly, the switching pulse C2 (point C2) of the switch 5 is a rectangular pulse having the frequency ν / 2 and the second pulse width WC, and is synchronized with the switching pulse A, but is shifted from the switching pulse C1 by a half period. Yes.
[0054]
As shown in the figure, the output (point D) from the booster circuit 6 is a pulsating voltage in which a + side pulse and a − side pulse appear alternately at a frequency ν / 2.
[0055]
Since the width of this pulse is WC and the height is Vp, that is, almost proportional to the first pulse width WA, the DC voltage output through the rectifying / smoothing circuit 7 is equal to the first pulse width WA and the second pulse width WA. Is substantially proportional to the product (WA × WC) with the pulse width WC.
[0056]
Actual voltage control is usually performed by setting the second pulse width WC to the maximum (about 80% of the period) and changing the first pulse width WA.
[0057]
Then, when the first pulse width WA reaches the lower limit value (about 10% of the period) and the voltage is to be further lowered, the second pulse width WC is lowered.
[0058]
As described above, in the high voltage generator and the X-ray generator according to the present embodiment, the switch 2 that conducts the DC voltage at the frequency ν with the first pulse width WA is passed, and this is passed through the low pass filter 3. The pulsating voltage obtained here is boosted by the booster circuit 6 through the switches 4 and 5 that are conducted in synchronization with the switch 2 with the second pulse width WC, and this is rectified and smoothed to obtain the first pulse. By obtaining a DC high voltage substantially proportional to the product of the width WA and the second pulse width WC (WA × WC), and changing the first pulse width WA and the second pulse width WC, Since the voltage output and applied to the X-ray tube 9 is controlled, a large voltage control range can be obtained, and the responsiveness is excellent and the stability is extremely stable compared with the method of controlling the DC power supply. Control can be performed.
[0059]
In addition, since the voltage control range is wide, it is possible to deal with various X-ray tubes with a single device, standardization as a high voltage generating part (high voltage generating device), and low cost. The device can be supplied.
[0060]
Further, when one apparatus is compatible with various X-ray tubes, the X-ray tube type is set to the second pulse width WC (or the first pulse width WA) for an X-ray tube having a small output. It is also possible to use a method of protecting the X-ray tube 9 and the high-voltage generator by narrowing the control range of the voltage that can be widened by setting a fixed value corresponding to (or setting the upper limit value low). It becomes.
[0061]
In this case, since the voltage control range is wide, there is an advantage that the restriction can be given a large degree of freedom and the X-ray tube types that can be handled are increased.
[0062]
(Modification of the first embodiment)
(Modification 1)
In the first embodiment, in FIG. 1, elements that are not important to the invention are omitted.
[0063]
For example, a cathode lighting circuit for the cathode of the X-ray tube 9, a protection circuit associated with the switch, a coil and a capacitor for increasing the efficiency by resonating current are omitted.
[0064]
(Modification 2)
In the first embodiment, the DC power source 1 may not be a commercial AC power source.
[0065]
For example, a battery or a generator may be used.
[0066]
(Modification 3)
In the first embodiment, each of the switches 2, 4 and 5 may be switched on either the + side or the − side.
[0067]
That is, the switch 2 switches on the + side, but may switch on the − side.
[0068]
The same applies to the switches 4 and 5, and the + side may be switched.
[0069]
In this case, the connection to the booster circuit 6 is performed in the reverse direction, so that the negative side is connected to the midpoint of the primary winding of the booster circuit 6.
[0070]
(Modification 4)
In the first embodiment, each of the switches 2, 4 and 5 may be constituted by a plurality of switching elements, or may be switched on both the + side and the − side.
[0071]
FIG. 3 is a circuit diagram showing a modification of the switches 4 and 5 and the booster circuit 6.
[0072]
Here, the switches 4 'and 5' are switched on both the + side and the-side, respectively, and the directions of the currents flowing in the primary winding of the booster circuit 6 'due to the conduction of the switches 4' and 5 'are opposite to each other. It turns out that it has the same action as the first embodiment.
[0073]
(Modification 5)
In the first embodiment, a general circuit such as a rectifier (diode), a choke coil capacitor, or the like may be used as the rectifying / smoothing circuit 7, but a CW circuit that performs boosting and rectifying / smoothing simultaneously. May be used.
[0074]
In this case, since the boosting rate of the booster circuit 6 (transformer) is lowered, there is an advantage that a small circuit is sufficient.
[0075]
FIG. 4 is a circuit diagram showing modifications after the rectifying / smoothing circuit.
[0076]
This is an example using the CW circuit 12, the CW circuit 13, and the CW circuit 14, where (a) shows anode grounding, (b) shows midpoint grounding, and (c) shows cathode grounding.
[0077]
The CW circuit itself is composed of a rectifier (diode) and a capacitor ladder, and the illustrated one is an example.
[0078]
Note that the number of ladder steps is smaller than the actual number.
[0079]
(Modification 6)
In the first embodiment, both the booster circuit 6 and the rectifying / smoothing circuit 7 can be replaced with a CW circuit.
[0080]
FIG. 5 is a block circuit diagram showing a modification in which the voltage is boosted only by the CW circuit.
[0081]
In FIG. 5, a DC power source 15 is a power source having terminals on the + side and-side of the midpoint ground.
[0082]
The switch 16 switches the + − side.
[0083]
The low-pass filter 17 converts each pulse waveform on the + − side into a pulse shape with a low peak and a wide width.
[0084]
The switches 18 and 19 switch each of the inputs to the + − side again.
[0085]
Outputs from the switches 18 and 19 are input to the CW circuit 12, the CW circuit 13, or the CW circuit 14 of FIG.
[0086]
The output from the CW circuit is applied to the X-ray tube 9.
[0087]
A voltage control unit (not shown) gives switching pulses A1 and A2 to the switch 16, and gives switching pulses C1 and C2 to the switches 18 and 19, respectively.
[0088]
The switching pulses A1 and A2 have a first pulse width WA at a frequency ν and are out of phase with each other by a half period.
[0089]
The switching pulses C1 and C2 are emitted in synchronization with the switching pulses A1 and A2, respectively, at a frequency ν and a second pulse width WC.
[0090]
As a result, the voltage at the input point D of the CW circuits 12, 13, and 14 becomes a pulsating voltage in which the + side pulse and the − side pulse appear alternately at the frequency ν.
[0091]
With respect to such an input, the CW circuits 12, 13, and 14 are boosted, rectified and smoothed to obtain a high voltage.
[0092]
In this case, as in the case of the first embodiment, the DC voltage output through the CW circuits 12, 13, and 14 is the product of the first pulse width WA and the second pulse width WC ( Since it is substantially proportional to (WA × WC), the voltage control range can be increased, and the responsiveness is improved, so that stable and accurate control can be performed.
[0093]
(Modification 7)
In the first embodiment, when a self-rectifying tube type X-ray tube is used with an AC input, the rectifying / smoothing circuit 7 can be omitted, and the output from the booster circuit 6 is supplied to the X-ray tube 9. Can be connected directly.
[0094]
(Modification 8)
In the first embodiment, the frequency of the switching pulses C1 and C2 can generally be ν / n (n is an integer).
[0095]
(Second Embodiment)
FIG. 6 is a block circuit diagram showing a schematic configuration example of a high voltage generator according to the present embodiment and an X-ray generator to which the high voltage generator is applied. The same elements as those in FIG. Is omitted, and only different parts will be described here.
[0096]
That is, as shown in FIG. 6, the high voltage generator and the X-ray generator according to the present embodiment include the two switches 4 and 5 and the booster circuit 6 in FIG. The configuration is replaced with.
[0097]
Here, the switch 21 includes a switching transistor.
[0098]
In FIG. 6, one side is switched, but the + side may be switched.
[0099]
The output from the switch 21 is input to the primary coil of the booster circuit 22 including a booster transformer.
[0100]
Next, the operation of the high voltage generator and the X-ray generator according to the present embodiment configured as described above will be described with reference to FIG.
[0101]
FIG. 7 is a time chart showing a change in voltage of each part over time.
[0102]
In FIG. 6, as in the case of the first embodiment, the switching pulse A (point A) of the switch 2 is a rectangular pulse having the frequency ν and the first pulse width WA, and the switch 2 is the first pulse. Conduction is made during the width WA.
[0103]
The output from the switch 2 has almost the same voltage waveform as that at point A, but the output from the low-pass filter 3 (point B) is converted into a pulse shape with a low peak and a wide pulse waveform.
[0104]
This peak value Vp is substantially proportional to the first pulse width WA.
[0105]
A switching pulse C (point C) of the switch 21 is a rectangular pulse having a frequency ν and a second pulse width WC, and is synchronized with the switching pulse A.
[0106]
As shown in the figure, the output (point D) from the booster circuit 22 is a pulsating voltage where only one side pulse appears at the frequency ν.
[0107]
Since the width of this pulse is WC and the height is Vp, that is, almost proportional to the first pulse width WA, the DC voltage output through the rectifying / smoothing circuit 7 is equal to the first pulse width WA and the second pulse width WA. Is substantially proportional to the product (WA × WC) with the pulse width WC.
[0108]
As described above, the high voltage generator and the X-ray generator according to the present embodiment can obtain the same effects as those of the first embodiment.
[0109]
(Modification of the second embodiment)
This is the same as Modification 1 to Modification 8 of the first embodiment.
[0110]
(Third embodiment)
FIG. 8 is a block circuit diagram showing a schematic configuration example of the X-ray generator according to the present embodiment. The same elements as those in FIG. State.
[0111]
In FIG. 8, a circuit for heating a filament 41 as a heat source in the cathode 40 of the X-ray tube 9 has a configuration similar to a circuit for obtaining a high voltage.
[0112]
Reference numeral 42 denotes an anode (anode) of the X-ray tube 9, and 43 denotes a target of the X-ray tube 9.
[0113]
The output from the DC power supply 31 is input to the switch 32, and the output from the switch 32 is input to the low pass filter 33.
[0114]
The output from the low-pass filter 33 is input in parallel to the switch 34 and the switch 35, respectively.
[0115]
Outputs from the switches 34 and 35 are input to the transformer 36.
[0116]
The + side of the output from each switch 34 and switch 35 is connected to the midpoint of the primary winding of the transformer 36, and the − side of the output from each switch 34 and switch 35 is one of the primary winding of the transformer 36. One end is connected to the other end of the primary winding of the transformer 36, respectively.
[0117]
The output from the transformer 36 is input to the filament 41.
[0118]
The current measuring unit 37 converts the tube current of the X-ray tube 9 into a voltage and inputs the voltage to the current control unit 38.
[0119]
The current setting unit 39 inputs the set current value to the current control unit 38.
[0120]
The current control unit 38 gives the switching pulse A, the switching pulse C1, and the switching pulse C2 to the switch 32, the switch 34, and the switch 35, and changes the first pulse width and the second pulse width to thereby change the X-ray tube. The tube current is controlled so that the measured value of the tube current flowing through 9 matches the set value.
[0121]
Next, the operation of the X-ray generator according to this embodiment configured as described above will be described.
[0122]
The tube current flowing through the X-ray tube 9 is controlled in the same way as the tube voltage control in the first embodiment, and the time change of the voltage of each part is the same as the case shown in FIG. Become.
[0123]
In FIG. 8, the switching pulse A (point A) of the switch 32 is a rectangular pulse having a frequency ν and a first pulse width WA, and the switch 32 becomes conductive during the first pulse width WA.
[0124]
The output from the switch 32 has almost the same voltage waveform as that at point A, but the output from the low-pass filter 33 (point B) is converted into a pulse shape with a low peak and a wide width.
[0125]
This peak value Vp is substantially proportional to the first pulse width WA.
[0126]
A switching pulse C1 (point C1) of the switch 34 is a rectangular pulse having a frequency ν / 2 and a second pulse width WC, and is synchronized with the switching pulse A.
[0127]
Similarly, the switching pulse C2 (point C2) of the switch 35 is a rectangular pulse having the frequency ν / 2 and the second pulse width WC, and is synchronized with the switching pulse A, but is shifted from the switching pulse C1 by a half period. Yes.
[0128]
As shown in the figure, the output (point D) from the transformer 36 is a pulsating voltage in which a + side pulse and a − side pulse appear alternately at a frequency ν / 2.
[0129]
Since the width of this pulse is WC and the height is Vp, that is, approximately proportional to the first pulse width WA, the effective voltage applied to the filament 41 is the product of the first pulse width WA and the second pulse width WC. It is approximately proportional to (WA × WC).
[0130]
When the voltage applied to the filament 41 changes, the temperature of the filament 41 changes and thermoelectrons change, so that the tube current flowing through the X-ray tube 9 changes.
[0131]
The current control unit 38 compares the current value set by the current setting unit 39 with the tube current measured by the current measurement unit 37, and the first pulse width WA and the second pulse width are set so that they match. The tube current flowing through the X-ray tube 9 is controlled by changing the pulse width WC.
[0132]
As described above, in the X-ray generator according to the present embodiment, the switch 32 that conducts the DC voltage with the first pulse width WA at the frequency ν is passed, this is passed through the low-pass filter 33, and the second pulse width WC. Then, the filament 41 of the X-ray tube 9 is passed through the switches 34 and 35 which are conducted in synchronization with the switch 32, and the product of the first pulse width WA and the second pulse width WC is obtained by the pulsating voltage obtained here. The tube current flowing through the X-ray tube 9 is changed by changing the first pulse width WA and the second pulse width WC by heating with an effective voltage substantially proportional to (WA × WC) and changing the first pulse width WA and the second pulse width WC. Therefore, it is possible to obtain a large control range of the tube current and to perform highly stable and highly accurate control as compared with the method of controlling the DC power supply.
[0133]
Moreover, since the control range of the tube current is widened, it is possible to cope with various X-ray tubes with one device, standardization as a circuit for heating the filament 41, and supply an inexpensive device. Is possible.
[0134]
(Modification of the third embodiment)
(Modification 1)
In the third embodiment, the transformer 36 is not an essential component, and can be omitted as necessary.
[0135]
However, in this case, since the anode is grounded, since the ground level of the entire filament heating circuit becomes a high voltage, insulation is necessary.
[0136]
This method has an advantage that it is convenient because no insulation is required when the cathode is grounded.
[0137]
(Modification 2)
Since the method of changing the output voltage in the third embodiment is the same as the method in the first embodiment, it can be modified in the same manner as in the first embodiment.
[0138]
(Modification 3)
In the third embodiment, as in the case of the first embodiment, the DC power source 1 may be a commercial AC power source or a battery or a generator.
[0139]
(Modification 4)
In the third embodiment, as in the case of the first embodiment, each of the switches 32, 34, and 35 may be switched on either the + side or the − side.
[0140]
(Modification 5)
In the third embodiment, as in the case of the first embodiment, each of the switches 32, 34, and 35 may be composed of a plurality of switching elements. Both may be switched.
[0141]
(Modification 6)
In the third embodiment, as in the case of the second embodiment, the switches 34 and 35 may be configured by one switch.
[0142]
(Other embodiments)
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation.
In addition, the embodiments may be combined as appropriate as possible, and in that case, the combined effects can be obtained.
Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements.
For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem (at least one) described in the column of the problem to be solved by the invention can be solved, and the effect of the invention can be solved. When (at least one of) the effects described in the column can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0143]
【The invention's effect】
As described above, according to the high voltage generator of the present invention, the first switch that conducts the DC voltage at the predetermined frequency with the first pulse width is passed, and this is passed through the low-pass filter and the second pulse. Passing through at least one second switch that conducts in synchronism with the first switch in width, boosts the pulsating voltage obtained here to approximately the product of the first pulse width and the second pulse width Since the voltage output from the booster is controlled by changing the first pulse width and the second pulse width by obtaining a proportional high voltage, the voltage control range is wide and extremely stable. Voltage control can be performed.
[0144]
Further, according to the X-ray generator of the present invention, the voltage output from the boosting means is applied to the X-ray tube, so that the control range of the tube voltage is wide and extremely stable voltage control is performed. Is possible.
[0145]
Furthermore, according to the X-ray generator of the present invention, the first switch that conducts the DC voltage at the predetermined frequency with the first pulse width is passed through the first switch with the second pulse width. An pulsating current having an effective voltage approximately proportional to the product of the first pulse width and the second pulse width obtained here is passed through at least one second switch that is conducted in synchronization with the switch of the X-ray. The X-ray tube is applied to the tube heat source (cathode filament) and the first pulse width and the second pulse width are changed to change the temperature of the X-ray tube heat source (change the thermoelectrons). Therefore, the tube current control range is wide and extremely stable tube current control can be performed.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a first embodiment of a high voltage generator according to the present invention and an X-ray generator to which the high voltage generator is applied.
FIG. 2 is a time chart showing the time change of the voltage of each part in the high voltage generator and the X-ray generator of the first embodiment;
FIG. 3 is a circuit diagram showing a fourth modification of the first embodiment of the high-voltage generator according to the present invention and the X-ray generator to which the high-voltage generator is applied.
FIG. 4 is a circuit diagram showing a fifth modification of the first embodiment of the high-voltage generator according to the present invention and the X-ray generator to which the high-voltage generator is applied.
FIG. 5 is a block circuit diagram showing a sixth modification of the first embodiment of the high-voltage generator according to the present invention and the X-ray generator to which the high-voltage generator is applied.
FIG. 6 is a block circuit diagram showing a second embodiment of a high voltage generator according to the present invention and an X-ray generator to which the high voltage generator is applied.
FIG. 7 is a time chart showing temporal changes in voltages of respective parts in the high voltage generator and the X-ray generator of the second embodiment.
FIG. 8 is a block circuit diagram showing a third embodiment of the X-ray generator according to the present invention.
FIG. 9 is a block circuit diagram showing a schematic configuration example of a conventional X-ray generator of only a step-up transformer type.
[Explanation of symbols]
1 ... DC power supply
2 ... Switch
3 ... Low-pass filter
4 ... Switch
4 '... switch
5 ... Switch
5 '... switch
6 ... Booster circuit
6 '... Booster circuit
7 ... Rectification / smoothing circuit
8 ... Voltage measurement unit
9 ... X-ray tube
10 ... Voltage controller
11 ... Voltage setting section
12 ... CW circuit
13 ... CW circuit
14 ... CW circuit
15 ... DC power supply
16 ... switch
17 ... Low-pass filter
18 ... Switch
19 ... Switch
21 ... Switch
22: Booster circuit
31 ... DC power supply
32 ... Switch
33 ... Low-pass filter
34 ... Switch
35 ... Switch
36 ... Trans
37 ... Current measuring section
38 ... Current control unit
39: Current setting section
40 ... Cathode
41 ... Filament
42 ... Anode
43 ... Target
A ... Switching pulse
C1 ... Switching pulse
C2 ... Switching pulse
WA: First pulse width
WC ... second pulse width
Vp: peak value.

Claims (3)

DC power supply that outputs DC voltage;
A first switch for the output of the pulse waveform of the rows that have a predetermined frequency input and a switching operation of the output from the DC power source,
A low-pass filter that receives an output of a pulse waveform from the first switch and converts the pulse waveform into a pulse shape having a low peak and a wide width ;
At least one second switch for performing a switching operation using an output from the low-pass filter as an input;
Boosting means for boosting to a high voltage and outputting the output from the second switch as an input;
First with providing a switching pulse in a first pulse width at the predetermined frequency to the first switch, the first to the second switch in synchronization with the switching pulse of the predetermined frequency or a predetermined By applying a second switching pulse with a second pulse width at a frequency of 1 / n (n is an integer) of the frequency, and changing the first pulse width and the second pulse width, Voltage control means for controlling the output voltage;
A high-voltage generator comprising: The high voltage generator according to claim 1,
An X-ray generator comprising an X-ray tube to which a voltage output from the booster is applied. DC power supply that outputs DC voltage;
A first switch for the output of the pulse waveform of the rows that have a predetermined frequency input and a switching operation of the output from the DC power source,
A low-pass filter that receives an output of a pulse waveform from the first switch and converts the pulse waveform into a pulse shape having a low peak and a wide width ;
At least one second switch for performing a switching operation using an output from the low-pass filter as an input;
An X-ray tube having, as a cathode, a heat source to which an output from the second switch is applied;
First with providing a switching pulse in a first pulse width at the predetermined frequency to the first switch, the first to the second switch in synchronization with the switching pulse of the predetermined frequency or a predetermined By applying a second switching pulse with a second pulse width at a frequency of 1 / n (n is an integer) of the frequency, and changing the first pulse width and the second pulse width, the X-ray tube Current control means for controlling the tube current flowing through the X-ray tube by changing the temperature of the heat source;
An X-ray generator comprising:

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