JPH1069013A - X-ray image photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a film and a screen in an adequate close-contact condition at a photographing part by phase-controlling a vacuum pump based on pressure detected at a pressure detecting part, so that the internal pressure of a sealed space is kept to a nearly specified target value. SOLUTION: A vacuum control part 70 controls power applied on the vacuum pump 90 by phase control based on an electric signal in accordance with the inside pressure inputted from the pressure detecting part 60, so that the internal pressure of the sealed space becomes a predetermined value. When the internal pressure of the sealed space reaches the predetermined value, the part 70 receiving the electric signal in accordance with the internal pressure detected at the part 60 phase-controls to stop the driving of the pump 90. The part 70 receives the signal from the part 60 even after the internal pressure of the sealed space reaches the predetermined value, monitors difference between the internal pressure and the specified value, and controls the internal pressure of the sealed space by feeding back so as to keep the internal pressure of the sealed space to the predetermined value by phase-controlling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus, and more particularly, to an improvement in vacuum pressure control for bringing an X-ray film and an intensifying screen into close contact with each other in a vacuum in an imaging section.

[0002]

2. Description of the Related Art Conventionally, in the medical field in particular, a plurality of X-ray films are loaded into a photographing unit one by one from a magazine containing a plurality of X-ray films, and an X-ray transmission image of a subject is photographed at a predetermined position of the photographing unit. An X-ray image photographing apparatus adapted to perform this operation is well known (Japanese Patent Publication Nos. 5-67215 and 6-68608).

In this X-ray image photographing apparatus, in order to increase the sensitivity of an X-ray transmission image of a subject recorded on the X-ray film, an intensifying screen is generally brought into close contact with the X-ray film at the photographing position from the front and rear. It is being done.

For this purpose, intensifying screens are each attached to two supports having a certain degree of flatness.

After the film is placed between the two supports, the distance between the two supports is reduced to bring the intensifying screen into close contact with the film, and photographing is performed in that state.

As a method of bringing the screen into close contact with the film, a mechanical method of applying a pressing force in the film direction to both supports by using a mechanical element such as a cam or a link is used. Using an annular sealing member (for example, packing) formed so as to surround the outer periphery of the X-ray film disposed in the space between the sealing member and the supporting member, The inside of the air is exhausted by a vacuum pump to reduce the internal pressure of this sealed space, the sealing member is elastically deformed by the pressure difference from the atmospheric pressure, and both supports are brought into close contact from the front and back of the film, a so-called vacuum adhesion method. It has been known.

The cross-sectional structure of the sealing member surrounding the outer periphery of the film generally comprises a base held by one support and a seam extending from the base toward the other support. In some cases, the seam portion is configured to be in close contact with the other support by elastic deformation.

[0008] Among the above-mentioned structures for intensifying the screen and the film, the vacuum adhesion method is said to be a more effective method because the intensifying screen can be uniformly brought into close contact with the film.

[0009]

By the way, in the conventional photographing apparatus, a predetermined pressure inside the closed space is detected in order to prevent the pressure inside the closed space from becoming extremely low (the degree of vacuum becomes high). A pressure switch that operates in response to the pressure is provided, and the pressure reducing operation is stopped when the pressure switch is operated.

[0010] This is because when the pressure inside the sealed space becomes extremely low, the screen comes into close contact with the periphery of the X-ray film, causing the screen to be injured, and photographing using a larger size film is performed later. This is to prevent the problem that the screen is scratched on the film and the reading performance of the reproduced image is deteriorated.

On the other hand, the internal pressure in the sealed space gradually decreases over time due to, for example, a slight dust floating in the air adhering to the contact surface of the sealing means and the sealing state being incomplete. Start to rise.

It is conceivable that a part of the film is exposed to the outside of the closed space and the exposed part is gripped by using various gripping means to facilitate the handling of the film. In addition, the sealing state by the sealing means becomes incomplete.

Although the internal pressure can be increased to a certain extent, it should not be increased to such a degree that proper contact between the film and the screen cannot be obtained.

However, in the conventional apparatus, as described above, although the lower limit of the pressure inside the closed space is monitored, the upper limit is not limited, so that the internal pressure of the closed space reaches the lower limit and preparation for photographing is performed. If a long time is required due to interruption or the like between completion and actual photographing, the close contact between the film and the screen may be insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an X-ray imaging apparatus capable of maintaining a proper contact between a film and a screen in an imaging section. It is.

[0016]

An X-ray imaging apparatus according to the present invention comprises an X-ray image capturing apparatus in an enclosed space surrounded by a pair of opposing intensifying screens and a sealing member provided on the periphery of the intensifying screen. An X-ray imaging apparatus having an imaging unit arranged with a X-ray film, wherein the intensifying screen is brought into close contact with the X-ray film by evacuating the air inside the sealed space using a vacuum pump, A pressure detection unit that detects the internal pressure of the sealed space, and based on the pressure detected by the pressure detection unit, by controlling the phase of the vacuum pump, sets the internal pressure of the sealed space to a substantially constant target value. And a control unit for maintaining.

The X-ray film is not limited to the one entirely housed in the closed space, but may be a part of which is exposed from the closed space. When the film is arranged so that part of it is exposed from the enclosed space, it is convenient to handle the film because it is easy to grip the exposed part of the film from outside the enclosed space. Is preferable.

Although the present invention does not specifically state that a pressure leak portion is provided separately, it does not prevent the active provision of such a pressure leak portion.

In the case where the X-ray film is partially exposed from the closed space, the film crosses the contact surface of the sealing member. Although the air leaks into the enclosed space little by little, this also does not prevent the pressure leak portion from being actively provided, and the air inflow from the crossing portion is very small. If it is difficult to reduce the increased degree of vacuum, it is desirable to provide a separate pressure leak portion.

Further, during a period from the start of the vacuum pump until the internal pressure reaches the predetermined target value, the control unit controls the vacuum pump so that its output is maximized, After the pressure reaches the predetermined target value, the control method may be switched so as to perform the phase control.

Further, the vacuum pressure control device of the present invention comprises a pressure detecting section for detecting an internal pressure of a predetermined enclosed space, a vacuum pump for exhausting air inside the enclosed space to the outside, A control unit for controlling the phase of the vacuum pump based on the internal pressure thus determined, to maintain the internal pressure of the closed space at a substantially constant target value.

Here, the predetermined enclosed space is, for example, in an X-ray imaging apparatus, a space surrounded by the sucker and the film when the X-ray film is separated using a sucker or the like.

Also, in the present invention, it is not explicitly stated that a pressure leak portion is separately provided, but this does not prevent the positive provision of such a pressure leak portion.

Further, during a period from the start of the vacuum pump to the time when the internal pressure reaches the predetermined target value, the control unit controls the vacuum pump so that the output thereof is maximized. After the pressure reaches the predetermined target value, the control method may be switched so as to perform the phase control.

[0025]

According to the X-ray imaging apparatus of the present invention, the control section controls the vacuum pump based on the internal pressure of the closed space detected by the pressure detecting section, so that the pressure in the contact space during the imaging period is controlled. Variations can be prevented, and as a result, the close contact between the X-ray film and the intensifying screen can be maintained substantially constant within a desired range during the imaging period.

In this vacuum pressure control, since the phase of the vacuum pump itself is electrically controlled, the vacuum pressure control can be performed at low cost and with high accuracy.

Further, during the period from the start of the vacuum pump to the time when the internal pressure of the sealed space reaches a predetermined target value, the control unit controls the vacuum pump so that the output thereof is maximized. After the internal pressure of the vacuum pump reaches a predetermined target value, the control method is switched so that phase control is performed. Can be minimized.

According to the vacuum pressure control device of the present invention, the control unit controls the vacuum pump based on the internal pressure of the closed space detected by the pressure detection unit, thereby preventing pressure fluctuation in the close space.

In this vacuum pressure control, since the phase of the vacuum pump itself is electrically controlled, the vacuum pressure control can be performed at low cost and with high accuracy.

Further, during the period from the start of the vacuum pump to the time when the internal pressure of the closed space reaches a predetermined target value, the control unit controls the vacuum pump so that the output of the vacuum pump is maximized. After the internal pressure of the vacuum pump reaches a predetermined target value, the control method is switched so that phase control is performed. Can be minimized.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the X-ray imaging apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of the X-ray image photographing apparatus, FIG. 2 is a block diagram of a pressure control system in the photographing section of the X-ray image photographing apparatus shown in FIG. 1, and FIG. FIG. 3 is a diagram illustrating a more detailed configuration of a vacuum pressure control unit of the pressure control system illustrated in FIG.

The illustrated X-ray image photographing apparatus 100 is for photographing an X-ray transmission image 300 having a chest of a human body as an object on an X-ray film 1a or 1b. Two supply magazines 21 and 22 for accommodating a large number of two types of unexposed X-ray films 1a and 1b of different lengths, respectively, and the above-mentioned two films based on a film selection instruction from a film selection means (not shown). Film 1 from either supply magazine 21 or 22
a transport means provided with transport rollers 33, 34, 35, 36, and 37 for transporting the sheet-feeding means 31 and 32 for taking out the sheets a and 1b one by one and the taken-out film 1a and the like to a photographing section 40 to be described later from above; An imaging unit 40 having a front support 41 and a rear support 42 for holding the X-ray film 1a and the like in close contact from the front and back at the imaging position, and a sealed space S described later sandwiched between the two supports 41 and 42. A vacuum pressure control system for controlling the internal vacuum pressure, and X
An ID recording device 50 for recording the ID number and the like of the subject on a part (upper end) of the line film 1a and the like, a receiving magazine 23 for storing the photographed film 1a and the like, and a system control for performing various controls of the entire device And a section 80.

A chin rest, on which the subject mounts a jaw for positioning in the height direction, is located directly above the photographing section 40 of the main body 10.
11 are formed.

The rear surface and the rear support of the front support 41
Intensifying screens 41a and 42a are attached to the front of the screen 42, respectively.
The film 1a and the like are held between 42a.

Further, the rear support 42 is provided with a holding means (not shown) for holding the film 1a and the like that have entered the photographing section 40 by suction.

A packing 46 is provided on the periphery of the screens 41a, 42a attached to the supports 41, 42, and the gap between the screens 41a, 42a is provided when the screens 41a, 42a are close to each other. The space is both these screens
An airtight closed space S is formed by the packings 46a and 41a.

Here, as shown in FIG. 2, the vacuum pressure control system includes a pressure detecting section 60 for detecting the internal pressure of the closed space S.
A pressure leak section 65 for introducing the atmosphere into the closed space S in response to the opening and closing operation, a vacuum pump 90 for exhausting the air inside the closed space S, and a pressure detected by the pressure detecting section 60. A vacuum pressure control unit 70 is provided to maintain the internal pressure of the sealed space S at a substantially constant target value by controlling the phase of the vacuum pump 90 or controlling the opening / closing operation of the pressure leak unit 65.

The system control unit 80 detects the rear end of the X-ray film 1a or the like carried in the photographing unit 40 in the transport direction, and performs the carry-in operation at a position where the rear end coincides with the upper end of the photographing unit 40. This controls the entire operation of the X-ray image photographing apparatus of the present embodiment, including a control means for stopping the operation, a means for controlling the drive of the transport roller 33 and the like.

Both of the supports 41 and 42 are positioned almost vertically at the forefront (photographing position) of the photographing section 40 during photographing, but are linked when the film 1a or the like is loaded or unloaded. It is rotated (moved) backward in conjunction with the movement of 44 and 45.

One of the two sheet processing means 31 and 32 has one of them.
Is a thin film 1a, and the other 32 is a long film 1b, and the film 32 is advancing to the position indicated by the broken line in the drawing.These are, for example, in accordance with a film selection instruction input from an operator to a film selection means. Either one is driven. However, the present invention is not necessarily limited to the configuration in which the sheet means 31 and 32 are separately provided for each length of the film, and one sheet means is supplied in accordance with the film selection instruction and the supply magazine on the designated side. Of course, it is possible to adopt a configuration in which the film 1a or 1b of any length can be adsorbed by being moved to the opening 21 or 22.

Next, the operation of the X-ray imaging apparatus according to this embodiment will be described.

First, in this apparatus, a supply magazine 21 containing a short sheet-like unexposed X-ray film 1a and a supply magazine containing a long size sheet-like unexposed X-ray film 1b are provided. Magazine 22 is set.

Here, an operator's instruction is input from a film selecting means (not shown), and based on the instruction, the corresponding sheet processing means 31 or 32 is supplied from one of the two supply magazines 21 and 22 to the film 1a or 1a. Take out 1b one by one.

Since the following operation is the same regardless of the size instruction, the operation when the instruction is of a short size, that is, the operation on the short-sized film 1a will be described.

The sheet-feeding means 31 sucks the film 1a and draws it out of the supply magazine 21, and then moves to the transport roller 33 while holding the film 1a (shown by a broken line). As a result, the leading end of the film 1a in the transport direction is guided between the two transport rollers 33. At this time, the front support 41 and the rear support 42 of the photographing unit 40 are at a position rotated backward from the photographing position, and the upper end between the two supports 41 and 42 is open. .

That is, the rear support 42 is pulled backward by the rotation of the connected link 45 about the rotation center R4, and at this time, the pins 42e and 42f provided on both sides of the rear support 42 are provided.
Slides along the guides 13 and 14 of the main body 10, so that the rear support 42 is rotated rearward as a whole.

On the other hand, for the front support 41, the link 44
Is rotated around its center of rotation R3, thereby rotating the drive arm 43 connected to the other end of the link 44 around its center of rotation R2, and the forks 43b of the drive arm 43 are moved to both sides of the front support 41. Is moved backward. The lower end of the front support 41 is supported by the center of rotation R1, and the pin 41b moves along the guide 12, so that the front support 41 rotates rearward as a whole.

During this time, the transport rollers 33, 34, 35, 36, and 37 are driven to rotate, and hold the film 1a to transport the film 1a toward the photographing unit 40.

In the photographing section 40, the front support 41 and the rear support
42 is rotated backward from the shooting position,
A narrow wedge-shaped film loading space is formed between 41 and 42, and the film 1a transported by the transport rollers 37 is smoothly loaded into this space.

When the film 1a is carried between the supports 41 and 42, the film 1a is held at a predetermined position on the rear support 42 by the holding means of the rear support 42. With the film 1a held at the predetermined position in this manner, the two supports 41 and 42 return to the original photographing positions.

The operation when returning to the original photographing position is as follows.
This is achieved by an action opposite to the above-described action of turning backward.

The rear support 42 is adjusted to rotate after the front support 41 starts to rotate forward. This means that the rear support 42 not only rotates around the fixed center, but also moves along a substantially parallel linear movement as is apparent from the shapes of the guides 13 and 14, so that the rear support 42 and the front support Body 41
If you bring them together before returning them to their original shooting position,
During the movement to return to the photographing position, a slip occurs between the two 41 and 42, and a frictional force acts on the film 1a held between the two 41 and 42, thereby damaging the film 1a. is there.

In the photographing position, the two supports 41 and 42 are in close proximity, and a sealed space S is formed between the two screens 41a and 42a by the packing 46.

At this time, the entire film 1a is not accommodated in the closed space S, and the upper corner is exposed to the outside of the closed space S. This is for the convenience of handling the film 1a.

Hereinafter, the pressure control in the closed space S will be described with reference to FIG.

First, when both supports 41 and 42 return to the photographing position, a film setting completion signal is input to the system controller 80. In response to the input of this signal, the system control unit 80 outputs a signal for instructing the vacuum pressure control unit 70 to start pressure control inside the closed space S.

The vacuum pressure control unit 70 first drives the vacuum pump 90, and the pump 90 starts exhausting the air in the closed space S. At the same time, the pressure detector 60 starts detecting the internal pressure P of the closed space S. The detected internal pressure P is converted into an electric signal and input to the vacuum pressure control unit 70.

Based on the electric signal corresponding to the input internal pressure P, the vacuum pressure control unit 70 controls the power applied to the pump 90 by phase control so that the internal pressure P of the closed space S becomes a predetermined value. Control.

When the internal pressure P of the sealed space S reaches a predetermined value, the vacuum pressure control unit 70, which has received an electric signal corresponding to the internal pressure P detected by the pressure detection unit 60,
Phase control to stop the drive of
A signal indicating that the pressure in the closed space S has reached a predetermined value suitable for photographing is transmitted to the system control unit 80.

As a result, the system control unit 80 sets the closed space S
After waiting for the time necessary for the close contact between the film and the screen inside, it is determined that the preparation for photographing is completed, and control for irradiating X-rays is performed.
The transmitted X-ray image 300 of the subject is recorded on the film 1a on which a is appropriately adhered.

Here, even after the internal pressure P of the closed space S reaches a predetermined value, the vacuum pressure control unit 70
In response to the signal from 60, the difference between the internal pressure P and the predetermined value is monitored, and feedback control is performed so as to maintain the internal pressure P of the closed space S at a predetermined value by phase control.

Hereinafter, a more detailed operation of the vacuum pressure control unit 70 during operation of the vacuum pump will be described with reference to FIG.

Pressure detection signal input from pressure detection section 60
VPf is first input to the differential amplifier 71. Here, a voltage value VPs corresponding to a predetermined target pressure value (the predetermined value described above) is further input to the differential amplifier 71 from the second pressure setting unit 72b.

The differential amplifier 71 calculates the difference (VPs−VPf) between the two input values and amplifies the obtained difference (VPs−VPf) to obtain (VPs−VPf) · G1 (G1 is an amplification factor). )age,
Output to the adder 73.

On the other hand, the pressure detection signal VP from the pressure detector 60
f is also input to the voltage comparator 74. The voltage comparator 74 further receives a predetermined pressure determination level value from the first pressure setting section 72a.
VPh (= voltage value VPs according to the target pressure value) is input,
This voltage comparator 74 compares the two input VPf, VPh.

When the voltage comparator 74 satisfies VPh ≦ VPf,
That is, when the internal pressure P of the closed space S reaches the target value, the pressure in the closed space S is
A signal indicating that a predetermined value suitable for shooting is reached is transmitted.

The above signal (VPs-VPf) from the differential amplifier 71
A signal value Vθ corresponding to a predetermined phase angle reference voltage is also input from the phase angle reference voltage setting unit 72c to the adder 73 to which G1 has been input. Here, the signal (VPs-VPf) .G1 is a value that fluctuates positively or negatively across "0", and if control is performed based on such a value, the operation of the control becomes unstable. Therefore, in order to eliminate such instability, a certain value may be added to the signal (VPs-VPf) · G1 to raise the level so that the signal fluctuates only within a positive range, for example. Therefore, the above signal (VPs-VPf) · G1
The value to be added in consideration of the maximum fluctuation width of the above is the signal value Vθ corresponding to the phase angle reference voltage.

The control value Vm output from the adder 73 (=
(VPs−VPf) · G1 + Vθ) is input to the voltage / phase converter 75.

The voltage / phase converter 75 includes an insulating transformer 7
7. The zero cross pulse voltage of the 100 volt AC power supply 76 is input via the zero cross detector 78.

As a result, the control value Vm input from the adder 73 is converted into a phase value θ based on the characteristics of the voltage and phase in the AC power supply 76 and output.

The output phase value θ is input to a driver (noted as SSR in the figure) 79 for driving the vacuum pump 90.

The driver 79 is fired based on the input phase value θ and supplies a predetermined power to the vacuum pump 90.

As shown in FIG. 4, the voltage / phase converter 75 includes a PWM converter 75a, a monostable multivibrator 75b, an AND gate 75c, and a buffer.
75d.

While the above-described pressure control is being performed, imaging by X-ray exposure is performed as described above. After the end of the X-ray imaging, an imaging end signal is input from the system control unit 80 to the vacuum pressure control unit 60, and the vacuum pressure control unit 60 opens the pressure leak unit 65. As a result, a larger amount of air flows into the closed space S than the atmosphere, and the internal pressure rises sharply.

As a result, the screens 41a and 42a are separated from the film 1a.

After capturing the X-ray image 300, the rear support 42 and the front support 41 are moved rearward by the same operation as when the film is loaded. At this time, the film 1a is adsorbed and held on the rear support 42 by the holding means, so that the rear support
It rotates backwards together with 42.

Next, the unloading means (not shown) holds the film 1a, the holding of the rear support 42 by the holding means is released, and the film 1a is transported by the unloading means (not shown).
Handed over to 37. The transport roller 37 rotates in the direction opposite to the direction at the time of loading, and unloads the film 1a from the imaging unit 40.

The unloaded film 1a is temporarily stopped between the rollers 36 and 37. Here, ID information such as an ID number of the subject to be photographed is recorded by the ID recording device 50. The portion of the film 1a on which the ID information is to be recorded may be shielded in the imaging unit so that the X-ray 300 is not exposed.

The film 1a on which the ID information is recorded is housed in the receiving magazine 23 by the roller 35, and a series of photographing operations is completed.

As described in detail above, X of the present embodiment
According to the line image photographing apparatus, based on the internal pressure P of the closed space S detected by the pressure detection unit 60, the vacuum pressure control unit 70
Controls the vacuum pump 90 to prevent pressure fluctuations in the close contact space S during the photographing period. As a result, the state of close contact between the X-ray film 1a and the intensifying screens 41a and 42a is maintained at a desired constant during the photographing period. Value, and proper adhesion between the film and the screen can be maintained.

The vacuum pressure control unit 70 includes a vacuum pump
Since the phase of the 90 itself is electrically controlled, it is possible to perform inexpensive and highly accurate vacuum pressure control.

FIG. 5 shows that the vacuum pressure control unit 70 shown in FIG.
This is a configuration of a system using a PU. In the configuration shown in this drawing, the adder 73 and the differential amplifier 71 shown in FIG.
The functions of the voltage comparator 74 and the voltage / phase conversion circuit 79 are set to CP
U70a has. Also, the first and second pressure setting sections 72a,
The RAM and the ROM 70c have the functions of the phase angle reference voltage setting section 72c and the phase angle reference voltage setting section 72c. The CPU 70a includes an A / D converter 70d and an I / O port necessary for handling digital data.
70e and a program timer counter 70b.

The operation and effect of the embodiment shown in FIG. 5 are the same as those shown in FIG. 3, and the description thereof will be omitted.

Next, a second embodiment of the X-ray imaging apparatus of the present invention will be described. In this embodiment, the phase control as described above is performed during the period from the start of the vacuum pump 90 to the time when the internal pressure P of the sealed space S reaches a predetermined target value in the first embodiment. In this case, the control system is controlled so that the output of the vacuum pump 90 is maximized, and the control method is switched so that the phase of the vacuum pump 90 is controlled when the internal pressure P fluctuates thereafter.

That is, the overall schematic configuration is the same as that shown in FIG. 2, but the detailed configuration of the vacuum pressure control unit 70 is different from that shown in FIG. 3, as shown in FIG.

Hereinafter, the different vacuum pressure control section (the vacuum pressure control section of this embodiment is denoted by 70 ') will be described.

The illustrated vacuum control unit 70 'is different from the vacuum pressure control unit 70 shown in FIG. 3 during the period from the start of the vacuum pump 90 until the internal pressure P of the closed space S reaches a predetermined target value. A flip-flop 75e which is a switching means for switching to control such that the output of the vacuum pump 90 is maximized;
This configuration further includes an OR gate 75f and a second voltage comparator 74b that inputs a reset signal to the flip-flop 75e. Note that the first voltage comparator 74a in the figure corresponds to the voltage comparator 74 in FIG.

Next, the operation of this embodiment for switching between the two control methods will be described.

First, one control method is a method in which the phase of the vacuum pump 90 is controlled by the voltage / phase conversion circuit 75 as in the embodiment shown in FIG. That is, the pressure detector
The voltage according to the internal pressure of the enclosed space S detected by 60
The difference (VPs-VPf) between VPf and the voltage VPs corresponding to the target pressure set in the second pressure setting section 72b is amplified by the differential amplifier 71 (the amplification factor is set to G1) (VPs-VPf). ) ・
G1 is output to the adder 73, and the adder 73 is the sum of the signal value Vθ according to the phase angle reference voltage set in the phase angle reference voltage setting unit 72c and the above signal (VPs-VPf) · G1. The control value Vm (= (VPs−VPf) · G1 + Vθ) is calculated, the voltage / phase converter 75 converts the control value Vm into the corresponding phase value θ, and the SSR 79 is based on the phase value θ. To drive the vacuum pump 90.

On the other hand, another control method is a vacuum pump
During the period from the start of 90 to the time when the internal pressure P of the sealed space S reaches a predetermined target value, the control method is to maximize the output of the vacuum pump 90 without performing phase control.
The second voltage comparator indicates that the voltage VPf corresponding to the internal pressure of the closed space S detected by the pressure detecting unit 60 has become the same as the voltage VPs corresponding to the target pressure set in the second pressure setting unit 72b. Until 74b is detected, the flip-flop (F /
F) A control signal for maximizing the output of the vacuum pump 90 from the Q terminal of 75e is input to the OR gate 75f, and this control signal is input to the SSR 79 via the AND gate 75c. Operate with output.

Here, the significance of newly using the control method for maximizing the output of the vacuum pump 90 will be described.

First, immediately after the operation of the vacuum pump 90, the internal pressure of the sealed space S is far from the target pressure. Therefore, rather than performing the feedback control of the phase control immediately after the operation, the pump 90 is not driven until the target pressure is first reached. Operating at maximum output is advantageous in that the target pressure is reached earlier in time.On the other hand, when phase control is performed immediately after the operation of the vacuum pump 90, the maximum The operation of the pump is controlled in an output region close to the output, but phase control in a region close to the maximum output is disadvantageous in that control stability is lacking.

First, the system controller 80 is controlled by the vacuum pressure controller 70.
, A signal (control ON / OFF) for instructing to start the pressure control inside the sealed space S is output to the AND gate 75c and the flip-flop 75e of the vacuum pressure control unit 70.

The flip-flop 75e outputs a control signal for maximizing the output of the vacuum pump 90 from the Q terminal, and the output control signal is input to the OR gate 75f.

The flip-flop 75e has a voltage VPf corresponding to the internal pressure of the closed space S, and a voltage VPs corresponding to the target pressure.
A signal indicating that the above value has been obtained is output to the second voltage comparator 74b.
The control signal is output from the Q terminal until it is input from the Q terminal. When a signal indicating that the voltage VPf has become equal to or higher than the voltage VPs is input from the second voltage comparator 74b to the reset terminal, the control signal is output from the Q terminal. The output of the control signal from is stopped.

On the other hand, in addition to the control signal from the flip-flop 75e, the OR gate 75f has a vacuum pump from the voltage / phase conversion circuit 75 as in the embodiment shown in FIG.
A signal for controlling the phase of the flip-flop 75e is also input, but the OR gate 75f outputs the control signal from the flip-flop 75e while the control signal from the flip-flop 75e is being input. When no control signal is input from the voltage / phase conversion circuit 75, the phase control signal is output from the voltage / phase conversion circuit 75.

One of the above signals output from the OR gate 75f is input to the AND gate 75c, and
The signal 75c passes any of the signals output from the OR gate 75f while the control ON signal from the system control unit 80 is being input.

As a result, any one of the above signals passing through the OR gate 75f controls the driving of the SSR 79. Therefore, in response to the signal passing through the OR gate 75f, the vacuum pump 90 is driven by phase control or its output is maximized.

Here, the signal passing through the OR gate 75f is determined based on the signal input to the reset terminal of the flip-flop 75e, that is, whether or not the internal pressure of the closed space S has reached the target pressure. During the period until the internal pressure of the closed space S reaches the target pressure, the vacuum pump 90 is driven and controlled so that the output thereof is maximized, and after the internal pressure of the closed space S reaches the target pressure, The phase is controlled to keep the internal pressure substantially constant.

As described above, according to the X-ray imaging apparatus of this embodiment, immediately after the operation of the vacuum pump 90,
By operating at maximum output, it is possible to reduce the time required for the internal pressure of the sealed space S to reach the target pressure while performing stable control, and after reaching the target pressure, By controlling the phase of the vacuum pump 90, fluctuations in the internal pressure of the closed space S can be suppressed.

Note that also in this embodiment, the vacuum pressure control unit 70 can be configured as a system using a CPU.
Specifically, one having the same configuration as that shown in FIG. 5 can be employed.

Further, in each of the above embodiments, the form in which the closed space S of the X-ray image photographing apparatus is targeted has been described. However, the present invention is limited to such an apparatus which targets only the X-ray image photographing apparatus. Instead, for example, it is of course possible to target a closed space of a closed container.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first embodiment of an X-ray imaging apparatus according to the present invention.

FIG. 2 is a block diagram of a pressure control system in an imaging unit of the X-ray imaging apparatus shown in FIG.

FIG. 3 is a diagram showing a more detailed configuration of a vacuum pressure control unit of the pressure control system shown in FIG. 2;

FIG. 4 is a diagram showing a detailed configuration of a voltage / phase conversion circuit shown in FIG. 3;

FIG. 5 is a diagram showing an embodiment in which the vacuum pressure control unit shown in FIG. 2 is configured using a CPU.

FIG. 6 is a schematic diagram showing a second embodiment of the X-ray imaging apparatus of the present invention.

[Explanation of symbols]

 1a, 1b X-ray film 10 Main body 40 Imaging unit 41 Front support 41a, 42a Screen 42 Rear support 46 Packing 50 ID recording device 60 Pressure detection unit 65 Pressure leak unit 70 Vacuum pressure control unit 72a First pressure setting unit 72b Second pressure setting unit 72c Phase angle reference voltage setting unit 80 System control unit 90 Vacuum pump S Sealed space

Claims (4)

[Claims] An X-ray film is arranged in a sealed space surrounded by a pair of intensifying screens facing each other and a sealing member attached to a peripheral edge of the intensifying screen, and air inside the sealed space is removed. An X-ray imaging apparatus including an imaging unit configured to bring the intensifying screen into close contact with the X-ray film by evacuating using a vacuum pump, a pressure detection unit that detects an internal pressure of the sealed space, A control unit for controlling the phase of the vacuum pump based on the pressure detected by the pressure detection unit to maintain the internal pressure of the sealed space at a substantially constant target value. Line imaging device. 2. The control unit controls the vacuum pump so that its output is maximized during a period from the start of the vacuum pump until the internal pressure reaches the predetermined target value, 2. The X-ray imaging apparatus according to claim 1, wherein a control method is switched so that the phase control is performed after the internal pressure reaches the predetermined target value. 3. A pressure detector for detecting an internal pressure of a predetermined enclosed space, a vacuum pump for exhausting air inside the enclosed space to the outside, and a pressure detector based on the internal pressure detected by the pressure detector. A controller for maintaining the internal pressure of the closed space at a substantially constant target value by controlling the phase of the vacuum pump. 4. The control unit controls the vacuum pump so that its output is maximized during a period from the start of the vacuum pump until the internal pressure reaches the predetermined target value; 4. The vacuum pressure control device according to claim 3, wherein a control method is switched so that the phase control is performed after the internal pressure reaches the predetermined target value.