JP7596945B2 - Radiography equipment - Google Patents

Description

The present invention relates to a radiography device.

Radiography devices have many factors that cause current fluctuations, such as image reading and wireless transfer, which generate electromagnetic field noise from the internal electronic circuit boards, wiring between boards, and batteries. This electromagnetic field noise propagates to the TFT (thin film transistor) sensor module that detects radiation and is superimposed as noise on the image signal of the radiation image, causing noise such as horizontal streaks in the obtained radiation image, which can significantly degrade image quality.
Therefore, one of the generally known means for reducing the electromagnetic field noise generated from the internal electronic circuit board is to place a metal shield between the electronic circuit board and the TFT sensor module (see, for example, Patent Document 1).
On the other hand, because the noise reduction effect of a shield is determined by (shield area) x (shield thickness), a thicker (shield thickness) can achieve a greater noise reduction effect, but the weight of the shield increases, which reduces its value for a radiographic imaging device known as a flat panel detector (FPD), for which portability is one of its values.

In the invention described in Patent Document 2, the wires are placed close to each other or in contact with each other, and the magnetic fields generated in each wire are made to cancel each other out, weakening the generated magnetic field or eliminating the magnetic field, thereby reducing the electromagnetic field noise in the TFT sensor module.

Patent No. 05743477 Patent No. 5811584

On the other hand, the inventors have found that the effect of electromagnetic field noise on the signal line of the TFT sensor module caused by a current flowing parallel to the signal line is more significant than the effect of a current flowing perpendicular to the signal line of the TFT sensor module.

The objective of the present invention is to reduce the noise in the signal output by the sensor module that detects radiation images by reducing the effect of noise caused by internal currents on the sensor module.

One aspect of the radiography device according to the present invention for solving the above problem comprises a sensor module having a plurality of radiation detection elements arranged two-dimensionally for detecting a radiographic image, an electronic circuit board on which a control circuit for controlling each part including the sensor module and generating a radiographic image is mounted, a plurality of batteries as a power source, and electrical conductors individually connecting the plurality of batteries to the electronic circuit board, the electrical conductors having a first section in which currents flow in opposite directions on the same line parallel to the signal line of the sensor module.

Another aspect of the radiographic imaging device according to the present invention includes a sensor module having a plurality of radiation detection elements arranged two-dimensionally for detecting a radiographic image, an electronic circuit board on which a control circuit is mounted for controlling each part including the sensor module and generating a radiographic image, a plurality of batteries as a power source, and electrical conductors that individually connect the plurality of batteries to the electronic circuit board, the plurality of batteries having internal conductive parts through which currents flow in opposite directions on the same line parallel to the signal line of the sensor module.

According to the present invention, by reducing the noise effect due to internal current on the sensor module that detects radiation images, it is possible to reduce noise in the signal output by the sensor module.

FIG. 1 is a schematic cross-sectional view of an example of a radiation imaging apparatus. FIG. 2 is a rear view (interior perspective) of the radiation imaging apparatus according to the arrangement of the first embodiment of the present invention. FIG. 13 is a rear view (interior perspective) of a radiation imaging apparatus according to a comparative example. FIG. 2 is a perspective view of a signal line and a power supply conductor for explaining the principle of canceling electromagnetic effects. 11 is a graph showing the level of electromagnetic field noise on each signal line. FIG. 13 is a rear view (interior perspective) of a radiation imaging apparatus according to a second embodiment of the present invention;

The following describes an embodiment of the present invention with reference to the drawings. However, the scope of the present invention is not limited to the following embodiment or those described in the drawings.

As shown in FIG. 1, a radiographic imaging apparatus 100 according to one embodiment of the present invention includes a housing including a front panel 1 and a back panel 2, a TFT sensor module 3, a lead sheet 4, a base 5, an electronic circuit board 6, a battery 7 as a power source, electrical conductors 8 and 9, etc.
From the front panel 1 side, a TFT sensor module 3, a lead sheet 4, and a base 5 are stacked in this order, and an electronic circuit board 6 and a battery 7 are mounted on the back surface of the base 5 facing the back panel 2.

The TFT sensor module 3 includes a plurality of radiation detection elements arranged two-dimensionally to detect radiation images. The radiation detection elements are semiconductor elements such as photodiodes and phototransistors. The radiation detection elements generate electric charges according to the amount of radiation they are exposed to. Switching elements made of TFTs are connected one-to-one to the radiation detection elements and arranged two-dimensionally. By controlling the on/off timing of these switching elements, analog detection signals from the radiation detection elements in each column are sent through signal lines.
The electronic circuit board 6 operates on power supplied from a battery 7, and is equipped with a control circuit that controls each section including the TFT sensor module 3 to generate a radiation image, as well as a power supply circuit and a communication circuit.
The above points are related to the prior art.
Fluctuating currents caused by the operation of the radiation imaging apparatus 100 can cause electromagnetic fields to be generated from the electronic circuit board 6 , the electrical leads 8 and 9 , and the battery 7 , which can become a cause of noise being generated in the TFT sensor module 3 .

First Embodiment
Fig. 2 shows a radiation imaging apparatus 100A according to the arrangement of the first embodiment of the present invention. Fig. 3 shows a radiation imaging apparatus 100Z according to the arrangement of a comparative example. The cross-sectional configuration shown in Fig. 1 is the same.

2 is an internal perspective view seen from the back panel 2 side, showing an electronic circuit board 6, two batteries 7A and 7B, and electrical conductors 8 and 9. Also shown at the back are signal lines 10 of the TFT sensor module 3. The signal lines 10 run parallel to each other in one direction (vertical direction).
Battery 7A is connected to electronic circuit board 6 by electrical conductor 8, and battery 7B is connected to electronic circuit board 6 by electrical conductor 9, respectively.
The wiring connecting the positive electrode of battery 7A to electronic circuit board 6 is designated as electrical conductors 8P1 and 8P2. The wiring connecting the negative electrode of battery 7A to electronic circuit board 6 is designated as electrical conductors 8N1 and 8N2. The wiring connecting the positive electrode of battery 7B to electronic circuit board 6 is designated as electrical conductors 9P1 and 9P2. The wiring connecting the negative electrode of battery 7B to electronic circuit board 6 is designated as electrical conductors 9N1 and 9N2.

The electric conductor 8P1 and the electric conductor 9P1 according to this embodiment correspond to a first section 11 in which currents flow in the opposite directions on the same line parallel to the signal line 10 of the TFT sensor module 3.
The electric conductor 8N1 and the electric conductor 9N1 according to this embodiment correspond to a first section 11 in which currents flow in the opposite directions on the same line parallel to the signal line 10 of the TFT sensor module 3.
The first section 11 is configured so that the amount of magnetic field generated by a current flowing in one direction is the same as the amount of magnetic field generated by a current flowing in the opposite direction. For this reason, in the embodiment shown in Fig. 2, the multiple batteries mounted are two batteries 7A, 7B of the same specifications, and a portion 8P1 (8N1) belonging to the first section 11 of the electrical conductor 8 connected to one battery 7A and a portion 9P1 (9N1) belonging to the first section 11 of the electrical conductor 9 connected to the other battery 7B have the same length and cross-sectional area.

2, when the two-dimensional array of the multiple radiation detection elements is viewed in plan, the electrical conductors 8 and 9 have a second section 12 that is perpendicular to the signal line 10 of the TFT sensor module 3. The electrical conductors 8P2, 8N2, 9P2, and 9N2 belong to the second section 12.
The second section 12 is longer than the first section 11. Specifically, the electrical conductor 8P2 is longer than the electrical conductor 8P1, the electrical conductor 8N2 is longer than the electrical conductor 8N1, the electrical conductor 9P2 is longer than the electrical conductor 9P1, and the electrical conductor 9N2 is longer than the electrical conductor 9N1.

Furthermore, the multiple batteries 7A, 7B according to this embodiment have internal conductive parts 7A1 and 7B1, and internal conductive parts 7A2 and 7B2, through which currents flow in opposite directions on the same line parallel to the signal line 10 of the TFT sensor module 3. The internal conductive parts 7A1 and 7B1 form a pair through which currents flow in opposite directions on the same line parallel to the signal line 10. Similarly, the internal conductive parts 7A2 and 7B2 form a pair through which currents flow in opposite directions on the same line parallel to the signal line 10.
In the embodiment shown in Figure 2, the multiple batteries 7A, 7B are arranged upside down so that the positive electrodes face each other and the negative electrodes face each other in a direction parallel to the signal line 10, and the batteries have internal conductive parts 7A1 and 7B1, and internal conductive parts 7A2 and 7B2, through which currents flow in opposite directions on the same line parallel to the signal line 10 of the TFT sensor module 3.
The current flowing in the batteries 7A and 7B flows from the negative electrode to the positive electrode over the entire surface of the battery, and the amount of current is greater closer to the electrode.

Noise may be superimposed on the signal line 10 due to the influence of the magnetic field generated by the current flowing through the electrical conductors 8 and 9, but the influence of the current running parallel to the signal line 10 is relatively large, and the influence of the current perpendicular to the signal line 10 is relatively small. The second section 12 is longer than the first section 11, but is arranged perpendicular to the signal line 10, so that the influence of noise from the second section 12 on the signal can be kept low.

In the radiation imaging apparatus 100A of this embodiment, the influence of the current running parallel to the signal line 10 on the signal is offset as follows.
That is, the effect on the signal line 10 of the current flowing through the electric conductor 8P1 and the effect on the signal line 10 of the current flowing through the electric conductor 9P1 are the same in magnitude but opposite in polarity, so they cancel each other out and the effect on the signal is suppressed. This cancellation principle will be explained with reference to Fig. 4. As shown in Fig. 4, the magnetic field generated by the electric conductor 8P1 and the magnetic field generated by the electric conductor 9P1 are in opposite directions. The signal flowing through the signal line 10i is affected by the magnetic field generated by the electric conductor 8P1 in the vicinity of the electric conductor 8P1, but is affected by the magnetic field generated by the electric conductor 9P1 in the vicinity of the electric conductor 9P1 with almost the same amount and opposite polarity, so they are canceled out. That is, by applying electromagnetic field noise of the same magnitude but opposite direction to the same signal line 10i, the noise effect is canceled out.
Due to a similar cancellation principle, the effect of the current flowing through electrical conductor 8N1 on signal line 10j and the effect of the current flowing through electrical conductor 9N1 on signal line 10j are the same magnitude but opposite polarity, so they cancel each other out and the effect on the signal is suppressed.

Furthermore, due to the same cancellation principle, the effect on signal line 10j of the current flowing through internal conductive portion 7A1 and the effect on signal line 10j of the current flowing through internal conductive portion 7B1 cancel each other out, and the effect on signal line 10i of the current flowing through internal conductive portion 7A2 and the effect on signal line 10i of the current flowing through internal conductive portion 7B2 cancel each other out, suppressing the effects on the signal.

As described above, according to the radiation imaging apparatus 100A of this embodiment, the noise effect on the TFT sensor module 3 of the magnetic field generated by the internal current can be reduced, thereby reducing noise in the signal output by the TFT sensor module 3.
In order to maximize the above-mentioned offsetting effect, the amount of magnetic field generated by the current flowing in one direction in the first section 11 is made equal to the amount of magnetic field generated by the current flowing in the opposite direction, as described above. Also, in the batteries 7A and 7B, the amount of magnetic field generated by the current flowing in one direction and the current flowing in the opposite direction with respect to the internal current flowing along the signal line 10 is made equal to the amount of magnetic field generated by the current flowing in the same direction.

In contrast, in the radiography device 100Z according to the comparative example arrangement shown in FIG. 3, currents flow in the same direction in the electrical conductors 8 and 9 and in the batteries 7A and 7B on the same line parallel to the signal line 10. Therefore, as shown by the solid line graph Z in FIG. 5, electromagnetic field noise increases significantly. In FIG. 5, the vertical axis represents the noise level, and the horizontal axis represents the horizontal coordinate axis of the image, which is perpendicular to the signal line. In the radiography device 100Z according to the comparative example shown in FIG. 3, the noise level included in the signal extracted from the signal lines 10i and 10j running parallel to the power supply current has a high peak as shown in FIG. 5. According to the radiography device 100A according to the present embodiment shown in FIG. 2, the overall noise level is kept low, including the signals extracted from the signal lines 10i and 10j, as shown by the dashed line graph A in FIG. 5.

Second Embodiment
Next, a second embodiment of the present invention in which the number of mounted batteries is three will be disclosed.
6 shows a radiation imaging apparatus 100B according to a second embodiment of the present invention. The cross-sectional configuration shown in FIG.
The radiation imaging apparatus 100B of this embodiment is equipped with three batteries 7C, 7D, and 7E. For simplicity, only the positive electrode wiring is shown.
As shown in FIG. 6, the positive wiring from the three batteries 7C, 7D, and 7E is defined as electrical conductor 21P, electrical conductor 22P, and electrical conductor 23P, and each section is defined as electrical conductor 21P1, 21P2, and 21P3, electrical conductor 22P1, 22P2, and 22P3, and electrical conductor 23P1, 23P2, and 23P3.

The electrical conductor 21P2, the electrical conductor 22P2, and the electrical conductor 23P2 belong to the first section 11. Note that the electrical conductor 22P2 is disposed on the same line as the electrical conductor 21P2 and the electrical conductor 23P2, but is drawn shifted from them in the drawing.
The effect of the current flowing through electrical conductor 21P2 on signal line 10k and the effect of the current flowing through electrical conductors 22P2 and 23P2 on signal line 10k are the same in magnitude but opposite in polarity, so they cancel each other out and the effect on the signal is suppressed.
In order to maximize this offsetting effect, the amount of current flowing from each of the batteries 7C, 7D, and 7E is adjusted.
Therefore, by changing the thickness of each of the electrical conductors 21P, 22P, and 23P and the length to the electronic circuit board 6, the impedance of the wiring is changed and the amount of current flowing through each of the electrical conductors 21P, 22P, and 23P is adjusted.
Furthermore, among the electrical conductors 21P2, 22P2, and 23P2, the longer the section that runs parallel to the signal line 10, the greater the magnetic field influence on the signal line 10. Therefore, the degree of influence on the signal line 10 is adjusted by adjusting the length of the electrical conductor 21P2 connected to battery 7C and the lengths of the electrical conductors 22P2 and 23P2 connected to batteries 7D and 7E.
As described above, the effect (magnet field generation amount) on the signal line 10k caused by the current flowing through the electrical conductor 21P2 and the effect (magnet field generation amount) on the signal line 10k caused by the current flowing through the electrical conductors 22P2 and 23P2 are adjusted to be equal in magnitude. As a result, the effects (magnet field generation amount) on the signal line 10k from both are equal in magnitude but opposite in polarity, so they cancel each other out and the effect on the signal is suppressed.

The electrical conductors 21P1 and 21P3, the electrical conductors 22P1 and 22P3, and the electrical conductors 23P1 and 23P3 belong to the second section 12.
The second section 12 (21P1 + 21P3, 22P1 + 22P3, 23P1 + 23P3) is longer than the first section 11 (21P2, 22P2, 23P2), but is arranged perpendicular to the signal line 10, so that the noise influence from the second section 12 to the signal can be kept low.
Furthermore, the three batteries 7C, 7D, and 7E are also arranged so that their internal currents are perpendicular to the signal line 10, so that the influence of noise on the signals from the internal currents of the batteries 7C, 7D, and 7E can be kept low.

Although not shown in the figure, the negative wiring of batteries 7C, 7D, and 7E can also be arranged to have a first section and a second section, similar to the positive wiring, to reduce the effect of noise on signal line 10.

As described above, according to the radiation imaging apparatus 100B of this embodiment, the noise effect on the TFT sensor module 3 of the magnetic field generated by the internal current can be reduced, thereby reducing noise in the signal output by the TFT sensor module 3.
In order to maximize the above-mentioned cancellation effect in the radiation imaging apparatus 100B, the amount of magnetic field generated by a current flowing in one direction in the first section 11 is made equal to the amount of magnetic field generated by a current flowing in the opposite direction.
According to the above embodiment, the magnetic fields generated from the battery and its wiring are not weakened by canceling each other out, but are allowed to affect the signal line 10 as they are, and the magnetic field effects of opposite directions are applied to the same signal line, thereby canceling out the effects on the signal line.
According to the above embodiment, a sufficient noise reduction effect can be obtained without disposing a shield between the electronic circuit board 6, the battery 7, the electrical conductors 8 and 9, and the TFT sensor module 3, and therefore it is possible to provide a user with a radiography device that can be constructed lightweight and does not compromise both image quality and portability.

Reference Signs List 1 Front plate 2 Back plate 3 TFT sensor module 4 Lead sheet 5 Base 6 Electronic circuit board 7 Battery 7A, 7B Battery 7A1 Internal conductive portion 7A2 Internal conductive portion 7B1 Internal conductive portion 7B2 Internal conductive portions 7C, 7D, 7E Batteries 8, 9 Electrical conductor 10 Signal line 11 First section 12 Second section 21P, 22P, 23P Electrical conductor 100 Radiation imaging device 100A Radiation imaging device (first embodiment)
100B Radiation imaging apparatus (second embodiment)
100Z Radiography Apparatus (Comparative Example)

Claims (8)

a sensor module including a plurality of radiation detection elements arranged two-dimensionally for detecting a radiation image;
an electronic circuit board on which a control circuit for controlling each unit including the sensor module and generating a radiation image is mounted;
Multiple batteries as a power source;
and electrical leads individually connecting the plurality of batteries to the electronic circuit board;
The electrical conductor has a first section through which currents flow in opposite directions on the same line parallel to a signal line of the sensor module. The radiographic imaging device according to claim 1, which is configured so that the amount of magnetic field generated by a current flowing in one direction in the first section is equal to the amount of magnetic field generated by a current flowing in the opposite direction. The radiography device according to claim 1, wherein the plurality of batteries are two batteries of the same specifications, and the portion of the electrical conductor connected to one battery that belongs to the first section and the portion of the electrical conductor connected to the other battery that belongs to the first section have the same length and cross-sectional area. When the two-dimensional array of the plurality of radiation detection elements is viewed in a plan view, the electrical conductor has a second section that is perpendicular to a signal line of the sensor module,
The radiation imaging apparatus according to claim 1 , wherein the second section is longer than the first section. The radiographic imaging device according to any one of claims 1 to 4, wherein the plurality of batteries have internal conductive parts through which currents flow in opposite directions on the same line parallel to the signal line of the sensor module. The radiography device according to claim 5, wherein the batteries are arranged upside down so that they have internal conductive parts through which currents flow in opposite directions on the same line parallel to the signal line of the sensor module. a sensor module including a plurality of radiation detection elements arranged two-dimensionally for detecting a radiation image;
an electronic circuit board on which a control circuit for controlling each unit including the sensor module and generating a radiation image is mounted;
Multiple batteries as a power source;
and electrical leads individually connecting the plurality of batteries to the electronic circuit board;
The plurality of batteries have internal conductive parts through which currents flow in mutually opposite directions on the same line parallel to a signal line of the sensor module. The radiography device according to claim 7, wherein the batteries are arranged upside down so that they have internal conductive parts through which currents flow in opposite directions on the same line parallel to the signal line of the sensor module.

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