JP2000028736A - X-ray panel sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray panel sensor which can obtain an image of good quality. SOLUTION: In an X-ray panel sensor, analog circuits 17a, 17b, 18a, 18b, 19 are arranged on the surface side of a signal processing board 13 and digital circuits 20, 21 are arranged on its rear surface side. Noises which are outputted via the analog circuits 17a, 17b, 18a, 18b, 19 and which are to be superposed on the output signal of a MOS image sensor 5; i.e., noises of X-rays which are incident on the analog circuits 17a, 17b, 18a, 18b, 19 from the upper side and noises which are propagated to the analog circuits 17a, 17b, 18a, 18b, 19 from the lower side and which come from the digital circuits 20, 21 and from the outside; are suppressed by an X-ray shielding plate 27 and a first metal thin film 13c. Since the analog circuits 17a, 17b, 18a, 18b, 19 and the digital circuits 20, 21 are mounted on the surface and the rear surface of the signal processing board 13, the size of the X-ray panel sensor as a whole can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an X-ray panel sensor for capturing an X-ray image.

[0002]

2. Description of the Related Art A conventional X-ray panel sensor is disclosed in
No. 288184. This sensor is
A semiconductor image sensor is provided below the scintillator to detect X-rays.

[0003]

However, a high quality image cannot be obtained with the above-mentioned conventional X-ray panel sensor. That is, the output signal of the semiconductor image sensor may be superimposed with noise due to X-rays transmitted through the phosphor, a high-frequency drive signal of the semiconductor image sensor, and external noise. In particular, when the semiconductor image sensor is a large-sized MOS image sensor, a video line for transmitting an output signal is long, so that noise is easily superimposed on the output signal, and such noise causes image deterioration. . The present invention has been made in view of such a problem, and an object of the present invention is to provide an X-ray panel sensor capable of obtaining a higher quality image than before.

[0004]

In order to solve the above-mentioned problems, an X-ray panel sensor according to the present invention comprises a scintillator for converting an incident X-ray image into a fluorescent image and a MOS for capturing a fluorescent image converted by the scintillator. An X-ray panel sensor having a type image sensor, comprising: a first wiring board on which a MOS type image sensor is fixed, and a first metal thin film having a ground potential between upper and lower surfaces thereof; A second wiring board facing the lower side of the first wiring board and electrically connected to the first wiring board;
An X-ray shield interposed between the second wiring board and the ground potential, an analog circuit provided on the upper surface side of the second wiring board for performing analog processing on an output signal from the MOS image sensor; The MOS provided on the lower surface side
And a digital circuit for generating the timing of the drive signal of the type image sensor.

According to the X-ray panel sensor of the present invention, the MO
An analog circuit that performs analog processing on an output signal from the S-type image sensor is disposed on the upper surface side of the second wiring board, and further includes a first metal thin film of the second wiring board having a ground potential and an X-ray shielding plate. Placed between.

According to the X-ray panel sensor of the present invention, noise to be superimposed on the output signal of the MOS image sensor output via the analog circuit, that is, noise of X-rays incident on the analog circuit from above and A digital circuit and an external noise that propagate to the analog circuit from below are suppressed by the X-ray shielding plate and the first metal thin film, respectively.

Conventionally, an increase in noise due to an increase in the size of a MOS image sensor has caused image degradation, so that an X-ray panel sensor equipped with a large MOS image sensor capable of obtaining a high-quality image is realized. I couldn't do that.

On the other hand, according to the present invention, an X-ray panel sensor equipped with a large MOS image sensor (for example, vertical and horizontal dimensions = 50 mm × 50 mm) can be realized by reducing the noise. Since the first wiring board and the second wiring board are arranged to face each other and analog and digital circuits are mounted on the upper and lower surfaces of the second wiring board, the overall dimensions of the X-ray panel sensor can be reduced. it can. The present invention can be applied to an X-ray panel sensor equipped with a small MOS image sensor.

The second wiring board has a second metal thin film having a ground potential between upper and lower surfaces thereof, and the first and second metal thin films are electrically connected to grounds of an analog circuit and a digital circuit, respectively. Is desirable. The first and second metal thin films achieve the above-described noise shielding function, and can stabilize both circuits by being provided corresponding to the analog circuit and the digital circuit, respectively. .

Further, the X-ray panel sensor of the present invention has a first
And supporting the first wiring board on the second wiring board with the first wiring board interposed between the second wiring board, transmitting the output signal of the MOS image sensor to the analog circuit, and outputting the output signal of the digital circuit to the MOS image sensor. It is desirable to further include a connector for transmitting. In this case, since the connector itself that performs the above function supports the first wiring board on the second wiring board, the structural strength can be increased and the number of components can be reduced.

Further, if the X-ray panel sensor further includes a fiber optical plate containing lead and interposed between the scintillator and the MOS image sensor, the X-rays not converted by the scintillator can be converted to a MOS image. It can be shielded before reaching the light receiving surface of the sensor.

Further, an X-ray panel sensor is disposed around a fiber optical plate and an electronic element for a MOS type image sensor disposed on the first wiring board, and the X-ray panel sensor detects the incident X-ray image by X-rays. If the electronic device is further provided with a frame for shielding from X-rays, the electronic device can be shielded from X-rays by a frame disposed around the fiber optical plate.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an X-ray panel sensor according to an embodiment will be described. The same reference numerals are used for the same elements or elements having the same functions, and overlapping descriptions are omitted.

FIG. 1 is a plan view of an X-ray panel sensor.
FIG. 2 is a cross-sectional view of the X-ray panel sensor shown in FIG.

The present X-ray panel sensor uses Cu / Ni / Au
A frame 2 fixed on a wiring board 1 on which a wiring composed of: a fiber optical plate 3 whose outer edge is bonded to the inner edge of the frame 2 and which contains lead in silica glass;
A scintillator (phosphor) 4 provided on one surface of the fiber optical plate 3 for converting incident X-rays into fluorescence, and a semiconductor image provided on the wiring board 1 facing the other surface of the fiber optical plate 3 And a sensor 5 (MOS type image sensor).
The frame 2 has a fiber optical plate 3 at its inner edge.
Has a rectangular opening substantially the same as or slightly larger than the fiber optical plate 3. In addition, the fiber optical plate 3
Is perpendicular to the light receiving surface of the MOS image sensor 5.

The above members are arranged inside an iron housing 6,
A lid member 7 having a rectangular opening that defines an X-ray incident area is provided on the upper surface of the housing 6, and a window member 8 provided in the X-ray incident area is fixed to the lid member 7 from the inner surface side. . That is, the cover member 7 is formed of a metal (Fe) having a thickness of about 1 mm that blocks X-rays, and the window member 8 is formed of a resin (polycarbonate) having a thickness of about 0.5 mm that transmits X-rays. Note that a shielding film made of Cu / Ni / Au is formed on the back surface of the substrate so that X-rays transmitted through the wiring substrate 1 are reduced.

The MOS type image sensor 5 includes a plurality of photodiodes arranged two-dimensionally and a plurality of MOSFETs (electric field) for controlling reading of charges generated in the respective photodiodes in response to incident light. Effect transistor) and an electrode pad arranged around the light receiving region. M on the wiring board 1
Shift register 9 for controlling drive of OSFET
An amplifier element (amplifier array) 10 as an electronic element for amplifying the output of the MOS image sensor 5 is provided in a bare chip state, and is electrically connected to the electrode pad of the MOS image sensor by a bonding wire. Here, a thermosetting resin (epoxy resin) containing a conductive filler is interposed between the MOS image sensor 5, the shift register 9, the amplifier array 10, and the wiring board 1. It is electrically connected to the upper wiring and is physically fixed at the same time.

The wiring board 1 is fixed to the signal processing board 13 via a plurality of spacers 11 and 12 made of Al and a connector 16 erected from above the signal processing board (second wiring board) 13. The signal processing board 13 is fixed to the bottom surface of the housing 6 via a plurality of spacers 14 and 15 made of Al. The connector 16 is for electrically connecting the wiring board 1 and the signal processing board 13. Note that, in order to reduce the size of the entire device, the MOS image sensor 5 is arranged such that one corner is located near the corner of the wiring board 1. Therefore, since a spacer requiring screwing cannot be provided at this position, the spacer 11 interposed between the wiring board 1 and the signal processing board 13 at this position has a block shape.

FIG. 3 is a circuit diagram of the X-ray panel sensor shown in FIG. Hereinafter, referring to FIGS. 1 and 2,
The circuit configuration of the X-ray panel sensor will be described. On one surface of the signal processing board 13, an arithmetic processing circuit 1 for performing predetermined arithmetic processing on the video signal output from the amplifier array 10
7a, 17b, amplifiers 18a, 18b for amplifying the outputs of the arithmetic processing circuits 17a, 17b, and amplifiers 18a, 18
An analog circuit such as a multiplexer 19 for synthesizing the output of b by shifting it by a half cycle is provided.

The light receiving surface of the MOS type image sensor 5 has a first light receiving area defined by a row from address 0 to address 127 in the horizontal direction and a column perpendicular thereto, and a address from address 128 to 255 in the horizontal direction. , And a second light receiving area defined by a column perpendicular thereto.
A MOSFET for reading out signal charges is arranged at each address. Reading of signals from the photodiodes in the respective light receiving regions is performed simultaneously by controlling MOSFETs by the shift register 9, and reading of signals from the photodiodes is sped up.

The amplifier array 10 amplifies output signals from the first and second light receiving regions of the MOS type image sensor 5 based on a synchronization signal from the timing pulse generation circuit 20, respectively. It is composed of an array 10b. The arithmetic processing circuit 17a,
17b and the amplifiers 18a and 18b
a, 10b. Since the amplifier arrays 10a and 10b are provided on the wiring board 1, the MOS image sensor 5 and the amplifier arrays 10
a and 10b can be brought close to each other, the noise superimposed on these connection wirings can be reduced, and a high-quality image can be obtained. Even when the amplifier arrays 10a and 10b are brought close to each other, it is desirable that the influence of incident X-rays be reduced during imaging. Therefore, the frame 2 is made of a metal (Al or a metal having a large atomic weight) that shields X-rays, and the amplifier array 10 is provided at a position where incidence of X-rays is shielded by the metal.

At the same time, since the frame 2 covers the electrode pads of the MOS image sensor 5, the amplifier arrays 10a and 10b, and the shift register 9, the electrode pads and the amplifier arrays 10a and 10b, and the electrode pads and the shift register Is protected from an external load.

On the other surface of the signal processing board 13, a timing pulse generating circuit 20 for giving a signal readout timing and a signal amplification timing to the shift register 9 and the amplifier arrays 10a and 10b, respectively, and generating a drive signal composed of these. , And a digital circuit such as an oscillator 21 for generating a reference clock for the timing pulse generation circuit 20.

The multiplexer 19 combines the outputs of the amplifiers 18a and 18b with a shift of a half cycle in synchronization with the synchronization signal output from the timing pulse generation circuit 20. The video signal output from the multiplexer 19 is output from a video signal output terminal 24. In addition, the housing 6 has a changeover switch 26 for switching whether a trigger signal for driving the timing pulse generation circuit 20 is generated inside the device or generated externally, and a case where a trigger signal is input from the outside. An external trigger signal input terminal 25, a synchronization signal output terminal 23 for outputting a synchronization signal output from the timing pulse generation circuit 20, and a power supply connector 22 for supplying power to the entire apparatus are provided.

According to the X-ray panel sensor of this embodiment, when X-rays enter the sensor through the window member 8, the scintillator 4 emits fluorescent light in response to the X-rays. This fluorescence propagates along the optical axis direction of the MOS image sensor 5 without mixing with light passing between adjacent optical fibers in the fiber optical plate 3 which is an aggregate of a plurality of optical fibers. Light enters the light receiving surface. M
The signal output from the OS type image sensor 5 is amplified by being input to the amplifier array 10, input to the circuit on the signal processing board 10 via the connector 16,
It is output from the video signal output terminal 24.

Here, the connector 16 is connected to the first wiring board 1.
In addition, the first wiring substrate 1 is supported on the signal processing substrate 13 by being interposed between the signal processing substrates 13, and the output signal of the MOS image sensor 5 is output to the analog circuits 17 a, 17 b, 1.
8a, 18b, and 19 and transmitted to digital circuits 20, 21
Is transmitted to the MOS type image sensor 5. In the present embodiment, since the connector 16 itself supports the first wiring board 1 on the signal processing board 13, the structural strength can be increased and the number of components can be reduced.

In this embodiment, the signal processing board 1
Reference numeral 3 denotes a four-layer wiring board in which metal thin films 13a, 13c, 13e, and 13g and insulating thin films 13b, 13d, and 13f containing glass fibers are alternately stacked. The exposed metal thin films 13a and 13g are made of Cu / Ni / Au, and the internal metal thin films 13c and 13e are made of Cu.

Among these, the internal metal thin film 13c closest to the circuit formed on the upper surface of the signal processing board 13 is connected to the ground potential of the circuit formed on the upper surface of the signal processing board 13, and The internal metal thin film 13 e closest to the circuit formed on the back side of the processing board 13 is connected to the ground potential of the circuit formed on the back side of the signal processing board 13. In addition, these internal metal thin films 13c, 13e
Are electrically connected in only one place.

That is, the signal processing board 13 has a second metal thin film 13e having a ground potential between its upper and lower surfaces.
The first and second metal thin films 13c and 13e are electrically connected to the grounds of the analog circuits 17a, 17b, 18a, 18b and 19 and the digital circuits 20 and 21, respectively. The first and second metal thin films 13c and 13e are
The noise from the digital circuits 20 and 21 to the analog circuits 17a, 17b, 18a, 18b and 19 is shielded.
These are analog circuits 17a, 17b, 18a,
18b and 19 and the digital circuits 20 and 21, respectively, are provided to stabilize both circuits.

In order to suppress the incidence of X-rays on the signal processing board 13, a shielding plate 27 having a step is interposed between the wiring board 1 and the signal processing board 13, and the upper step of the shielding plate 27 is provided. The lower part is fixed to the signal processing substrate 13 by the spacer 29 by the spacer 28. The shielding plate 27 is made of brass whose surface is plated with Ni, and is connected to the ground potential.

As described above, the X-ray panel sensor according to the present embodiment comprises a scintillator 4 for converting an incident X-ray image into a fluorescent image and a MOS type image sensor 5 for picking up a fluorescent image converted by the scintillator 4. And a first wiring substrate 1 on which the MOS image sensor 5 is fixed, and a first metal thin film 13c having a ground potential between the upper and lower surfaces of the X-ray panel sensor. 1 and a signal processing board 13 arranged to be electrically connected to the first wiring board 1 and an X having a ground potential interposed between the first wiring board 1 and the signal processing board 13. A line shield plate 27 and analog circuits 17a, 17b, 1 provided on the upper surface side of the signal processing board 13 for analog processing of an output signal from the MOS image sensor 5
8a, 18b and 19, and digital circuits 20 and 21 provided on the lower surface side of the signal processing board 13 for generating the timing of the drive signal of the MOS type image sensor 5.

According to the X-ray panel sensor of the present embodiment, the amplifier array 10 for amplifying the output signal from the MOS image sensor 5 includes the MOS image sensor 5.
Analog circuits 17a, 1 which are arranged on the upper surface side of the first wiring board so as to shorten the connection distance between the circuit and the analog circuit, and further perform analog processing of the output from the amplifier array 10.
7 b, 18 a, 18 b, and 19 are disposed between the first metal thin film 13 c of the second wiring board 13 having the ground potential and the X-ray shield 27.

Therefore, the reduced connection distance improves the noise resistance of the output signal, and is superimposed on the output signal of the MOS type image sensor 5 output via the analog circuits 17a, 17b, 18a, 18b, and 19. Noise to be transmitted, that is, X-rays that pass through the scintillator 4 and the housing 6 from the upper side and enter the MOS image sensor 5, the amplifier array 10, and the analog circuit, and the analog circuits 17a, 17b, 18a, 18b, and 19 from the lower side. , M
Noise from the digital circuits 20 and 21 and external noise that propagates to the OS type image sensor 5, the amplifier array 10,
These are suppressed by the lead-containing fiber optical plate 3 and the frame 2, respectively, the X-ray shielding plate 27, and the first metal thin film 13c.

In this embodiment, the MOS type image sensor 5 and the amplifier array 10 have been described as being separate from each other, but they may be formed monolithically on the same semiconductor substrate. . Further, as shown in FIG. 4, the scintillator 4 can be formed directly on the MOS type image sensor 5.

Therefore, according to the above embodiment, by reducing the noise superimposed on the output signal, a large MOS type image sensor (length and width = 50 mm × 5)
0 mm) 5 can be realized. Since the analog circuits 17a, 17b, 18a, 18b, 19 and the digital circuits 20, 21 are mounted on the upper and lower surfaces of the signal processing board 13, the overall size of the X-ray panel sensor can be reduced.

As described above, the X-ray panel sensor according to the present embodiment can obtain high-quality images, and can be applied to high-performance measuring instruments such as medical instruments and space observation instruments. .

[0037]

As described above, as described above, the X according to the present invention is used.
According to the line panel sensor, the MOS type image sensor is formed on the first wiring substrate, and an analog circuit is provided between the X-ray shielding plate and the second wiring substrate having the metal thin film between the upper and lower surfaces. Since the digital circuit is arranged on the side, a higher quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of an X-ray panel sensor.

FIG. 2 is a cross-sectional view of the X-ray panel sensor shown in FIG. 1 taken along the line II-II.

FIG. 3 is a circuit configuration diagram of the X-ray panel sensor shown in FIG.

FIG. 4 is a cross-sectional view of an X-ray panel sensor according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wiring board, 2 ... Frame, 3 ... Fiber optical plate, 4 ... Scintillator, 5 ... Semiconductor image sensor, 10 ... Amplifying element, 17a, 17b, 18a, 18
b, 19: analog circuit, 20, 21: digital circuit.

Continuation of the front page (72) Inventor Akinaga Yamamoto 1126 Nomachi, Hamamatsu City, Shizuoka Prefecture F-term in Hamamatsu Photonics Co., Ltd. 2G088 FF02 GG15 GG19 JJ05 JJ06 JJ08 JJ29 JJ31 JJ33 JJ37 LL11

Claims (5)

[Claims] 1. An X-ray panel sensor comprising: a scintillator for converting an incident X-ray image into a fluorescent image; and a MOS image sensor for capturing a fluorescent image converted by the scintillator, wherein the MOS image sensor is positioned above the X-ray panel sensor. And a first metal thin film having a ground potential between the upper and lower surfaces thereof, facing a lower side of the first wiring substrate and electrically connected to the first wiring substrate. A second wiring board, an X-ray shielding plate having a ground potential interposed between the first and second wiring boards, and an MO provided on the upper surface side of the second wiring board.
An analog circuit that performs analog processing on an output signal from the S-type image sensor, and a digital circuit that is provided on a lower surface side of the second wiring board and generates a timing of a drive signal of the MOS-type image sensor. X to do
Line panel sensor. 2. The second wiring board has a second metal thin film having a ground potential between upper and lower surfaces thereof, and the first and second metal thin films are electrically connected to grounds of the analog circuit and the digital circuit, respectively. The X-ray panel sensor according to claim 1, wherein the X-ray panel sensor is electrically connected. 3. The method according to claim 1, wherein the first wiring board is supported on the second wiring board while being interposed between the first and second wiring boards, and an output signal of the MOS image sensor is transmitted to the analog circuit. The X-ray panel sensor according to claim 1, further comprising a connector for transmitting an output signal of the digital circuit to the MOS image sensor. 4. The apparatus according to claim 1, further comprising a lead-containing fiber optical plate interposed between the scintillator and the MOS image sensor.
2. An X-ray panel sensor according to claim 1. 5. The semiconductor device according to claim 1, wherein said M is disposed on said first wiring board.
5. The electronic device for an OS type image sensor, further comprising a frame disposed around the fiber optical plate and shielding the electronic device from X-rays of an incident X-ray image. X-ray panel sensor.