JP2005129909A - Optical sensor device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems associated with an optical sensor device composed of a thin film semiconductor element, and an electronic apparatus using the optical sensor device: (1) an increase in the cost and the mounting area of the optical sensor device resulted from a need to externally connect a circuit such as an amplifier IC to improve a load driving capacity due to the low current capacity of the sensor element in the optical sensor device using an amorphous silicon photodiode; and (2) the superimposing of noise caused by the connection of the photodiode and the amplifier IC on a printed circuit board. <P>SOLUTION: An amorphous silicon photodiode and an amplifier consisting of a thin film transistor are formed integrally on a substrate so that the load driving capacity is improved while reducing the cost and the mounting area. The superimposing of noise can be also reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical sensor device, and more particularly to an optical sensor device composed of a thin film semiconductor element. The present invention also relates to an electronic device using the optical sensor device.

  In recent years, with the advance of communication technology, mobile phones have become widespread. In the future, transmission of moving images and transmission of more information are expected. On the other hand, personal computers are also being produced with mobile-friendly products due to their light weight. A large number of information terminals called PDAs that have begun in electronic notebooks are also being produced and spread. Also, with the development of display devices, most of these portable information devices are equipped with flat panel displays.

  In such a display device, the brightness around the display device is detected and the display brightness is adjusted. In this way, wasteful power can be reduced by detecting ambient brightness and obtaining appropriate display brightness. For example, such an optical sensor device for brightness adjustment is used in a mobile phone or a personal computer. (For example, Patent Document 1)

  In a display device using a projector, the convergence adjustment is performed using an optical sensor device. Convergence adjustment is adjustment of an image so that the image of each color of RGB does not shift. The position of the image of each color is detected using an optical sensor, and the image is arranged at the correct position. (For example, Patent Document 2)

  The optical sensor device used here is one using an amorphous silicon photodiode. Amorphous silicon photodiodes are characterized by low sensitivity on the long wavelength side, that is, in the infrared region, as compared to single crystal silicon photodiodes. FIG. 13 shows sensitivity characteristics of the amorphous silicon photodiode and the single crystal silicon photodiode. Amorphous silicon photodiodes have a characteristic that the sensitivity is low outside the visible light region, similar to human visual sensitivity. On the other hand, since single crystal silicon photodiodes are sensitive in the infrared region, there is a problem that when there is infrared light, the reaction differs from visual sensitivity. Therefore, an optical sensor device using an amorphous silicon photodiode is suitable in such a case.

The optical sensor device composed of the amorphous silicon photodiode as described above has the following problems. As described above, the amorphous silicon photodiode has an advantage that the photosensitivity is close to human visual sensitivity, but has a problem that its output current is smaller than that of the single crystal silicon photodiode. Therefore, it is difficult to move other circuits directly with an amorphous silicon photodiode, and an optical sensor device is configured by combining an amorphous photodiode 502, an external amplifier circuit 501, and a feedback resistor 503 as shown in FIG. The output current of the amorphous photodiode 502 is converted into a voltage by the feedback resistor 503 and taken out as a voltage output from the output terminal 504.
JP 2003-60744 A JP 2003-47017 A

  In the conventional optical sensor device as described above, since the amorphous photodiode 502, the external amplifier circuit 501, and the feedback resistor 503 are combined, there are problems such as high cost and large mounting area. Further, since the output of the amorphous photodiode 502 is connected to the external amplifier circuit 501 on the printed circuit board, there is a problem that noise is easily superimposed.

In order to solve the above problems, the present inventors considered to integrally form an optical sensor element and an amplifier circuit using a thin film transistor. An optical sensor element using amorphous silicon (such as an amorphous silicon photodiode) is usually formed on an insulating substrate. Similarly, since a thin film transistor is usually formed on an insulating substrate, both have many common points. In the optical sensor device of the present invention, an amplifier circuit composed of an optical sensor element and a thin film transistor (hereinafter referred to as TFT) is integrally formed on a substrate, whereby the cost and the mounting area can be reduced. Further, since the optical sensor element and the amplifier circuit are directly connected on the sensor substrate, noise is hardly superimposed.
Further, the present invention can be applied not only to amorphous silicon but also to a sensor element using polysilicon, such as a polysilicon photodiode.

  The configuration of the present invention is shown below.

  The present invention is an optical sensor device having an optical sensor element and an amplifier circuit, wherein the optical sensor element and the amplifier circuit are integrally formed on a substrate.

  In the above, the present invention is characterized in that the optical sensor element is constituted by a sensor element using amorphous silicon.

  In the above, the present invention is characterized in that the optical sensor element is constituted by an amorphous silicon photodiode.

  In the above, the present invention is characterized in that the optical sensor element is constituted by a sensor element using polysilicon.

  In the above, the present invention is characterized in that the optical sensor element is constituted by a polysilicon photodiode.

  The present invention is an optical sensor device having an optical sensor element and an amplifier circuit, wherein the amplifier circuit is composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate.

  The present invention is an optical sensor device having an optical sensor element and an amplifier circuit, wherein the amplifier circuit is an operational amplifier composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate. It is said.

  The present invention relates to an optical sensor device having an optical sensor element, an amplifier circuit, and a feedback resistor, wherein the amplifier circuit is an operational amplifier composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate, A feedback resistor is provided outside the substrate.

  The present invention is an optical sensor device having an optical sensor element, an amplifier circuit, and an IV conversion resistor, wherein the amplifier circuit is an operational amplifier composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate, The IV conversion resistor is provided outside the substrate.

  The present invention provides an optical sensor device having an optical sensor element, an amplifier circuit, and a level shift circuit, wherein the amplifier circuit and the level shift circuit are formed of thin film transistors, and the optical sensor element, the amplifier circuit, and the level shift circuit are on a substrate. It is characterized in that it is integrally formed.

  The present invention is characterized in that, in the above, the level shift circuit includes a P-channel TFT and a constant current source.

  The present invention is characterized in that, in the above, the level shift circuit includes an N-channel TFT and a constant current source.

  In the above, the present invention is characterized in that the connection electrode terminals on the substrate are four terminals.

  The present invention is characterized in that, in the above, the connection electrode terminals on the substrate are four terminals, and two of them are power supply terminals.

  The present invention relates to an optical sensor device having an optical sensor element and an amplifier circuit, wherein the amplifier circuit is a current mirror circuit composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate. It is a feature.

  In the above, the present invention is characterized by a multi-gate structure in which a plurality of TFT gates constituting a current mirror circuit are formed.

  In the above, the present invention is characterized in that the current mirror circuit is configured by cascode connection.

  In the above, the present invention is characterized in that the current mirror circuit is configured by a Wilson connection.

  In the above, the present invention is characterized in that the current mirror circuit is constituted by an improved Wilson connection.

  The present invention is characterized in that, in the above, the amplification factor can be selected by arbitrarily changing the number of TFTs constituting the current mirror circuit, the gate length L, and the channel width W.

  The present invention is characterized in that, in the above, the current mirror circuit is composed of an N-channel TFT.

  The present invention is characterized in that, in the above, the current mirror circuit is constituted by a P-channel TFT.

  In the above, the present invention is characterized in that the connecting electrical electrode on the substrate has two terminals.

The present invention is as described above.
The optical sensor element and the amplifier circuit are integrally formed on a plastic substrate.

The present invention is as described above.
The optical sensor element and the amplifier circuit are integrally formed on a glass substrate.

  The present invention is an electronic device including the above-described optical sensor device.

  As described above, in the optical sensor device of the present invention, the amplifier and the amplification circuit configured using the photodiode and the TFT are integrally formed on the sensor substrate, so that the cost and the mounting area can be reduced. Superposition can be reduced.

  Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

  In the embodiment of the present invention, an example in which a reverse voltage (also referred to as reverse bias) is applied to a photodiode and driven is shown. Therefore, a voltage is applied from the second electrode to the first electrode. Further, the first electrode is an electrode in contact with the p layer side in the amorphous silicon layer of the photodiode, and the second electrode is an electrode in contact with the n layer side in the amorphous silicon layer of the photodiode.

(Embodiment 1)
FIG. 1 shows a first embodiment of the present invention. In this embodiment, an amplifier circuit 101 and a photodiode 102 made of TFTs are integrally formed on a sensor substrate. The operation will be described below. The non-inverting input terminal of the amplifier circuit 101 is connected to the external power supply VBB. The external power source VBB has a potential between the high potential side power source VDD and the low potential side power source VSS of the amplifier circuit 101. The first electrode of the photodiode 102 is connected to the external power supply VBB, and the second electrode is connected to the inverting input terminal of the amplifier circuit 101 and the first terminal of the feedback resistor 103. The second terminal of the feedback resistor 103 is connected to the output terminal 104 of the amplifier circuit 101. Here, the feedback resistor 103 is not formed on the sensor substrate in order to reduce variation in the output voltage of the amplifier circuit 101. However, if the variation is not a problem, the feedback resistor 103 is formed on the sensor substrate. It is also possible.

When light is input to the photodiode 102, a photocurrent flows from the second electrode of the photodiode 102 to the first electrode. As a result, a current flows from the output terminal 104 of the amplifier circuit 101 to the feedback resistor 103, and a voltage is generated across the feedback resistor 103.
In this embodiment, since the driving capability of the amplifier circuit 101 can be increased, a load can be connected to the output terminal 104 and driven.

FIG. 7 shows the photodiode connected in the reverse direction to that shown in FIG. 7 includes an amplifier circuit 701, a photodiode 702, and a feedback resistor 703. The first electrode of the photodiode 702 is connected to the inverting input terminal of the amplifier circuit 701 and the feedback resistor 703, and the second electrode. Are connected to the external power supply VBB and the non-inverting input terminal of the amplifier circuit 701. The current flows from the external power supply VBB to the output terminal 704 of the amplifier circuit 701 through the photodiode 702 and the feedback resistor 703. Thus, both directions of the photodiode are possible.
In the present embodiment, the amplifier circuits 101 and 701 are described as operational amplifiers (op-amps), but the amplifier circuits 101 and 701 are not limited to operational amplifiers.
Further, the photosensor element is not limited to the photodiode.

(Embodiment 2)
FIG. 2 shows a second embodiment of the present invention. In the present embodiment, an amplifier circuit 201 and a photodiode 202 composed of TFTs are integrally formed on a sensor substrate. The operation will be described below. The non-inverting input terminal of the amplifier circuit 201 is connected to the first terminal of the IV conversion resistor 203 and the second electrode of the photodiode 202. The output terminal 204 of the amplifier circuit 201 is connected to the inverting input terminal, and the amplifier circuit 201 functions as a voltage follower. The first electrode of the photodiode 202 is connected to the external power supply VBB2. The second terminal of the IV conversion resistor 203 is connected to the external power supply VBB1. Here, the IV conversion resistor 203 is not formed on the sensor substrate in order to reduce variations in output voltage. However, if the variation is not a problem, the IV conversion resistor 203 may be formed on the sensor substrate. Is possible.

When light is input to the photodiode 202, a photocurrent flows from the second electrode of the photodiode 202 to the first electrode via the IV conversion resistor 203 from the external power supply VBB1. As a result, a voltage is generated across the IV conversion resistor 203.
That is, when light is not input and current does not flow to the photodiode 202, the same potential as VBB1 is output to the output terminal 204, and when light is input and current flows to the photodiode 202, it is proportional to the amount of current. As a result, the potential of the output terminal 204 decreases.
In this embodiment, since the driving capability of the amplifier circuit 201 can be increased, a load can be connected to the output terminal 204 and driven.

FIG. 8 shows the photodiode connected in the reverse direction to that shown in FIG. 8 includes an amplifier circuit 801, a photodiode 802, and an IV conversion resistor 803. The first electrode of the photodiode 802 is connected to the non-inverting input terminal of the amplifier circuit 801 and the IV conversion resistor 803, and Two electrodes are connected to the external power supply VBB2. The current flows from the external power supply VBB2 to the external power supply VBB1 via the photodiode 802 and the IV conversion resistor 803. Thus, both directions of the photodiode are possible.
In the present embodiment, the amplifier circuits 201 and 801 are described as operational amplifiers (op-amps), but the amplifier circuits 201 and 801 are not limited to operational amplifiers.
In addition, other photosensor elements are not limited to photodiodes.

(Embodiment 3)
FIG. 3 shows a third embodiment of the present invention. In the present embodiment, an amplifier circuit 301, a photodiode 302, and level shift circuits 305 and 306 each composed of a TFT are integrally formed on a sensor substrate. The operation will be described below. The input of the level shift circuit 305 is connected to the low potential side power supply VSS, and the output thereof is connected to the non-inverting input terminal of the amplifier circuit 301. The input of the level shift circuit 306 is connected to the second electrode of the photodiode 302 and the first terminal of the feedback resistor 303, and its output is connected to the inverting input terminal of the amplifier circuit 301. The second terminal of the feedback resistor 303 is connected to the output terminal 304 of the amplifier circuit 301. The first electrode of the photodiode 302 is connected to the low potential side power source VSS. Here, the feedback resistor 303 is not formed on the sensor substrate in order to reduce variation in the output voltage of the amplifier circuit 301. However, if the variation is not a problem, the feedback resistor 303 is formed on the sensor substrate. It is also possible.

When light is input to the photodiode 302, a photocurrent flows from the second electrode of the photodiode 302 to the first electrode. As a result, a current flows from the output terminal of the amplifier circuit 301 to the feedback resistor 303, and a voltage is generated across the feedback resistor 303.
In the present embodiment, since the driving capability of the amplifier circuit 301 can be increased, a load can be connected to the output terminal 304 and driven.

  The advantages of using such a level shift circuit are as follows. An outline view of the integrated sensor chip 600 is shown in FIG. As shown in FIG. 6A, a photodiode portion 601 and an amplifier circuit portion 602 are formed on the upper surface of the chip 600. As shown in the side view of FIG. 6B and the bottom view of FIG. 6C, connection electrode terminals 605 are formed on the bottom surface of the chip substrate 603 and the TFT formation region 604. In such a sensor chip, it is desirable in terms of strength to form connection electrode terminals at four points on the chip and mount them on a printed circuit board or the like. However, in the first embodiment described above, since the number of terminals is five, this is not satisfied.

In the first embodiment, a power source VBB is required in addition to the high potential side power source VDD and the low potential side power source VSS. Therefore, by using the level shifter, the number of power supplies can be reduced as shown in FIG.
In the present embodiment, the amplifier circuit 301 is described as an operational amplifier (op-amp), but the amplifier circuit 301 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

(Embodiment 4)
FIG. 4 shows a fourth embodiment of the present invention. In the present embodiment, an amplifier circuit 401, a photodiode 402, and level shift circuits 405 and 406 made of TFT are integrally formed on a sensor substrate. The operation will be described below. The input of the level shift circuit 405 is connected to the first terminal of the IV conversion resistor 403 and the second electrode of the photodiode 402, and the output is connected to the non-inverting input terminal of the amplifier circuit 401. The input of the level shift circuit 406 is connected to the output terminal 404, the output is connected to the inverting input terminal of the amplifier circuit 401, and the amplifier circuit 401 functions as a voltage follower. The first electrode of the photodiode 402 is connected to the low potential side power source VSS of the amplifier circuit 401. The second terminal of the IV conversion resistor 403 is connected to the external power supply VBB. Here, the IV conversion resistor 403 is not formed on the sensor substrate in order to reduce variations in the output voltage. However, if the variation is not a problem, the IV conversion resistor 403 may be formed on the sensor substrate. Is possible.

When light is input to the photodiode 402, a photocurrent flows from the second electrode of the photodiode 402 to the first electrode. As a result, a current flows through the IV conversion resistor 403, and a voltage is generated across the IV conversion resistor 403.
That is, when light is not input and current does not flow to the photodiode 402, the same potential as VBB is output to the output terminal 404, and when light is input and current flows to the photodiode 402, it is proportional to the amount of current. As a result, the potential of the output terminal 404 decreases.
In this embodiment, since the driving capability of the amplifier circuit 401 can be increased, a load can be connected to the output terminal 404 and driven.

  The advantages of using such a level shift circuit are as follows. An outline view of the integrated sensor chip is shown in FIG. As shown in FIG. 6A, a photodiode portion 601 and an amplifier circuit portion 602 are formed on the upper surface of the chip. Further, as shown in the side view of FIG. 6B and the bottom view of FIG. 6C, a connection electrode 605 is formed on the bottom surface of the chip. In such a sensor chip, it is desirable in terms of strength to form connection electrode terminals at four points on the chip and mount them on a printed circuit board or the like. However, in the second embodiment described above, since the number of terminals is five, this is not satisfied.

In the second embodiment, a power source VBB2 is required in addition to the high potential side power source VDD, the low potential side power source VSS, and the external power source VBB1. Therefore, by using the level shifter, the number of power supplies can be reduced as shown in FIG.
In the present embodiment, the amplifier circuit 401 is described as an operational amplifier (op-amp), but the amplifier circuit 401 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

(Embodiment 5)
FIG. 19 shows a fifth embodiment of the present invention. In this embodiment, an amplifier circuit 1901 and a photodiode 1902 made of TFTs are integrally formed on a sensor substrate. The operation will be described below. The source region of the TFT of the amplifier circuit 1901 is connected to the external power supply GND, and the drain region of the Y side TFT is connected to the output terminal 1904. The X-side TFT drain region of the amplifier circuit 1901 is connected to the first electrode of the photodiode 1902, and the second electrode is connected to the output terminal 1904.

When light is input to the photodiode 1902, a photocurrent flows from the second electrode of the photodiode 1902 to the first electrode. As a result, a current flows through the X-side TFT of the amplifier circuit 1901, and a voltage necessary to flow the current is generated at the gate.
If the number of Y-side TFTs connected in parallel, the gate length L, and the channel width W are equal to the X-side TFT, the same current flows in the saturation region because the gate voltages on both the TFT X-side and Y-side are equal. In order to obtain a desired amplification, for example, if “the number of TFTs on the X side: the number of TFTs on the Y side = 1: n”, the multiplication becomes n times (however, the other X side and Y side characteristics are the same).

  The TFT mounted on the circuit shown in FIG. 19A is an N-channel TFT, but a TFT using a P-channel TFT is shown in FIG. 19B. The photosensor circuit in FIG. 19B includes an amplifier circuit 1901 and a photodiode 1902. The drain region of the Y-side TFT of the amplifier circuit 1901 is connected to the external power supply GND, and the source region is connected to the output terminal 1904. . The drain region of the X-side TFT of the amplifier circuit 1901 is connected to the second electrode of the photodiode 1902, and the first electrode of the photodiode 1902 is connected to GND. In this embodiment, not only a photodiode but another optical sensor element may be used.

(Embodiment 6)
FIG. 20 shows a sixth embodiment of the present invention. In the present embodiment, an amplifier circuit 2001 and a photodiode 2002 composed of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFTs in the amplifier circuit 2001 are arranged in series on both the X side and the Y side, the source region and the drain region are connected, and the gates are connected in common to form a multi-gate structure. The source region of the low voltage side stage is connected to the external power supply GND, and the drain region of the Y side TFT high voltage side is connected to the output terminal 2004. The drain region of the X-side TFT high voltage side of the amplifier circuit 2001 is connected to the first electrode of the photodiode 2002, and the second electrode is connected to the output terminal 2004.

When light is input to the photodiode 2002, a photocurrent flows from the second electrode of the photodiode 2002 to the first electrode. As a result, a current flows through the X-side TFT of the amplifier circuit 2001, and a voltage necessary to flow the current is generated at the gate.
Since the gate voltages applied to both the X-side and Y-side TFTs are equal, the same current flows in the saturation region if the number of Y-side TFTs connected in parallel, the gate length L, and the channel width W are equal to those of the X-side TFT. To obtain the desired amplification, for example, if “X side TFT parallel connection number: Y side TFT parallel connection number = 1: n”, it becomes n times (however, the other X side and Y side characteristics are the same) And).
In this embodiment, the series connection of TFTs in the amplifier circuit 2001 is described as two stages, but the number of stages is not limited. The characteristics of the TFTs at each stage need not be the same, but the corresponding relationship between the X side and the Y side needs to be the same at each stage.

  The TFT mounted on the circuit shown in FIG. 20A is an N-channel TFT, and the circuit shown in FIG. 20B is a P-channel TFT. In this embodiment, not only a photodiode but another optical sensor element may be used.

(Embodiment 7)
FIG. 21 shows a seventh embodiment of the present invention. In this embodiment, an amplifier circuit 2101 and a photodiode 2102 made of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2101 is arranged in series on both sides of the X side and the Y side, the source region and the drain region are connected, and the gate connection is the diode side connection of the X side TFT, each of which is connected in series, Y The side TFT is connected to the gate of the opposite X side TFT. The source region of the low voltage side stage is connected to the external power supply GND, and the drain region of the Y side TFT high voltage side is connected to the output terminal 2104. The drain region of the X-side TFT high voltage side of the amplifier circuit 2101 is connected to the first electrode of the photodiode 2102, and the second electrode is connected to the output terminal 2104.

When light is input to the photodiode 2102, a photocurrent flows from the second electrode of the photodiode 2102 to the first electrode. As a result, a current flows through the X-side TFT of the amplifier circuit 2101, and a voltage necessary to flow the current is generated at each gate.
Since the gate voltage applied to both the X-side and Y-side TFTs is the same in each corresponding stage, if the number of Y-side TFTs connected in parallel, the gate length L, and the channel width W are equal to the X-side TFT, the same in the saturation region Current flows. To obtain the desired amplification, for example, if “X side TFT parallel connection number: Y side TFT parallel connection number = 1: n”, it becomes n times (however, the other X side and Y side characteristics are the same) And).
In the present embodiment, the series connection of TFTs in the amplifier circuit 2101 is described as two stages, but the number of stages is not limited. The characteristics of the TFTs at each stage need not be the same, but the corresponding relationship between the X side and the Y side needs to be the same at each stage.

  The TFT mounted on the circuit shown in FIG. 21A is an N-channel TFT, and the circuit shown in FIG. 21B is a P-channel TFT. In this embodiment, not only a photodiode but another optical sensor element may be used.

(Embodiment 8)
FIG. 22 shows an eighth embodiment of the present invention. In this embodiment, an amplifier circuit 2201 and a photodiode 2202 made of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2201 is connected by a Wilson current mirror circuit, the source region of the low voltage side stage is connected to the external power supply GND, and the drain region of the Y side TFT is connected to the output terminal 2204. The X-side TFT drain region of the amplifier circuit 2201 is connected to the first electrode of the photodiode 2202, and the second electrode is connected to the output terminal 2204.

When light is input to the photodiode 2202, a photocurrent flows from the second electrode of the photodiode 2202 to the first electrode. As a result, a current flows through the X-side TFT of the amplifier circuit 2201, and a voltage required to flow the current is generated at each gate. In the Wilson current mirror circuit, if the number of Y-side TFTs connected in parallel, the gate length L, and the channel width W are equal to those of the X-side TFT, the same current flows in the saturation region. To obtain the desired amplification, for example, if “X side TFT parallel connection number: Y side TFT parallel connection number = 1: n”, it becomes n times (however, the other X side and Y side characteristics are the same) And).
In the present embodiment, the series connection of TFTs in the amplifier circuit 2201 is described as two stages, but the number of stages is not limited. The characteristics of the TFTs at each stage need not be the same, but the corresponding relationship between the X side and the Y side needs to be the same at each stage.

  The TFT mounted on the circuit shown in FIG. 22A is an N-channel TFT, and the circuit shown in FIG. 22B is a P-channel TFT. In this embodiment, not only a photodiode but another optical sensor element may be used.

(Embodiment 9)
FIG. 23 shows a ninth embodiment of the present invention. In the present embodiment, an amplifier circuit 2301 and a photodiode 2302 configured by TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2301 has an improved Wilson current mirror circuit connection. The difference from the Wilson type current mirror circuit shown in FIG. 22 is that the number of TFTs on the X side and the Y side is made the same so that the source-drain voltages applied to the corresponding TFTs are made the same. Even if the output resistance is finite, the currents flowing on both sides of the X side and the Y side are equal. The source region of the low voltage side stage of the amplifier circuit 2301 is connected to the external power supply GND, and the drain region of the Y side TFT is connected to the output terminal 2304. The X-side TFT drain region of the amplifier circuit 2301 is connected to the first electrode of the photodiode 2302, and the second electrode is connected to the output terminal 2304.

When light is input to the photodiode 2302, a photocurrent flows from the second electrode of the photodiode 2302 to the first electrode. As a result, a current flows through the X-side TFT of the amplifier circuit 2301, and a voltage necessary to flow the current is generated at each gate.
Since the gate voltage applied to both the X-side and Y-side TFTs is the same in each corresponding stage, if the number of Y-side TFTs connected in parallel, the gate length L, and the channel width W are equal to those of the X-side TFT, the same current in the saturation region Flows. To obtain the desired amplification, for example, if “X side TFT parallel connection number: Y side TFT parallel connection number = 1: n”, it becomes n times (however, the other X side and Y side characteristics are the same) And).
In this embodiment, the series connection of TFTs in the amplifier circuit 2301 is described as two stages, but the number of stages is not limited. The characteristics of the TFTs at each stage need not be the same, but the corresponding relationship between the X side and the Y side needs to be the same at each stage.

  The TFT mounted on the circuit shown in FIG. 23A is an N-channel TFT, and the circuit shown in FIG. 23B is a P-channel TFT. In this embodiment, not only a photodiode but another optical sensor element may be used.

  FIG. 9 shows a first embodiment of the present invention. This embodiment is a specific implementation of Embodiment 3 using a level shift circuit. In this embodiment, two sets of level shift circuits each composed of an amplifying circuit 901 composed of TFTs, a photodiode 902, P-channel TFTs 905 and 906, and constant current sources 907 and 908 are integrally formed on a sensor substrate. . The operation will be described below. The input of the level shift circuit constituted by the P-channel TFT 905 and the constant current source 907 is connected to the low potential side power source VSS, and the output thereof is connected to the non-inverting input terminal of the amplifier circuit 901. The input of the level shift circuit constituted by the P-channel TFT 906 and the constant current source 908 is connected to the second electrode of the photodiode 902 and the first terminal of the feedback resistor 903, and the output is the inverting input terminal of the amplifier circuit 901. Connected to. The first electrode of the photodiode 902 is connected to the low potential side power source VSS. The second terminal of the feedback resistor 903 is connected to the output terminal 904 of the amplifier circuit 901. Here, the feedback resistor 903 is not formed on the sensor substrate in order to reduce variation in the output voltage of the amplifier circuit 901. However, when the variation is not a problem, the feedback resistor 903 is formed on the sensor substrate. It is also possible.

When light is input to the photodiode 902, a photocurrent flows from the second electrode 902 of the photodiode to the first electrode. As a result, a current flows from the output terminal 904 of the amplifier circuit 901 to the feedback resistor 903, and a voltage is generated across the feedback resistor 903.
In this embodiment, since the driving capability of the amplifier circuit 901 can be increased, a load can be connected to the output terminal 904 for driving.
In this embodiment, the connection electrode terminals of the photosensor device can be made into four terminals of a high potential side power supply VDD, a low potential side power supply VSS, an amplifier circuit 901 output terminal 904, and a feedback resistor 903-photodiode 902 connection terminal. The mounting strength can be improved. Further, by using the level shifter, the number of power supplies can be two.
In this embodiment, the amplifier circuit 901 is described as an operational amplifier (op-amp), but the amplifier circuit 901 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

  FIG. 10 shows a second embodiment of the present invention. This embodiment is a specific implementation of Embodiment 3 using a level shift circuit. In this embodiment, two sets of level shift circuits each formed by an amplifier circuit 1001, a photodiode 1002, N-channel TFTs 1005 and 1006, and constant current sources 1007 and 1008 each including a TFT are integrally formed on a sensor substrate. . The operation will be described below. The input of the level shift circuit constituted by the N-channel TFT 1005 and the constant current source 1007 is connected to the high potential side power supply VDD, and the output is connected to the non-inverting input terminal of the amplifier circuit 1001. The input of the level shift circuit composed of the N-channel TFT 1006 and the constant current source 1008 is connected to the first electrode of the photodiode 1002 and the first terminal of the feedback resistor 1003, and its output is the inverting input terminal of the amplifier circuit 1001. Connected to. The second electrode of the photodiode 1002 is connected to the high potential side power supply VDD. The second terminal of the feedback resistor 1003 is connected to the output terminal 1004 of the amplifier circuit 1001. Here, the feedback resistor 1003 is not formed on the sensor substrate in order to reduce variation in the output voltage of the amplifier circuit 1001. However, if the variation is not a problem, the feedback resistor 1003 is formed on the sensor substrate. It is also possible.

When light is input to the photodiode 1002, a photocurrent flows from the second electrode of the photodiode 1002 to the first electrode. As a result, a current flows to the output terminal 1004 of the amplifier circuit 1001 via the feedback resistor 1003, and a voltage is generated across the feedback resistor 1003.
In this embodiment, since the driving capability of the amplifier circuit 1001 can be increased, a load can be connected to the output terminal 1004 for driving.
In this embodiment, the connection electrode terminals of the photosensor device can be made into four terminals of the high potential side power supply VDD, the low potential side power supply VSS, the amplifier circuit 1001 output terminal 1004 and the feedback resistor 1003 -photodiode 1002 connection terminal. The mounting strength can be improved. Further, by using the level shifter, the number of power supplies can be two.
In this embodiment, the amplifier circuit 1001 is described as an operational amplifier (op-amp), but the amplifier circuit 1001 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

  FIG. 11 shows a third embodiment of the present invention. The present example is a specific example of the fourth embodiment described above. In this embodiment, an amplifier circuit 1101 composed of TFTs, a photodiode 1102, TFTs 1105 and 1106, and constant current sources 1107 and 1108 are integrally formed on a sensor substrate of two sets of level shift circuits. The operation will be described below. An input to a level shift circuit constituted by a P-channel TFT 1105 and a constant current source 1107 is connected to a first electrode of a photodiode 1102 and a first terminal of an IV conversion resistor 1103, and an output thereof is not connected to the amplifier circuit 1101. Connected to the inverting input terminal. The input of the level shift circuit constituted by the P-channel TFT 1106 and the constant current source 1108 is connected to the output terminal 1104 of the amplifier circuit 1101, and the output is connected to the inverting input terminal of the amplifier circuit 1101. Here, the amplifier circuit 1101 functions as a voltage follower. The second electrode of the photodiode 1102 is connected to the high potential side power supply VDD. The second terminal of the IV conversion resistor 1103 is connected to the external power supply VBB. Here, the IV conversion resistor 1103 is not formed on the sensor substrate in order to reduce variations in output voltage. However, if the variation is not a problem, the IV conversion resistor 1103 may be formed on the sensor substrate. Is possible.

When light is input to the photodiode 1102, a photocurrent flows from the second electrode of the photodiode 1102 to the first electrode. As a result, a current flows through the IV conversion resistor 1103 and a voltage is generated across the IV conversion resistor 1103.
That is, when light is not input and current does not flow to the photodiode 1102, the same potential as VBB is output to the output terminal 1104. When light is input and current flows to the photodiode 1102, the current is proportional to the amount of current. Thus, the potential of the output terminal 1104 rises.
In this embodiment, since the driving capability of the amplifier circuit 1101 can be increased, a load can be connected to the output terminal 1104 for driving.
In this embodiment, the connection electrode terminals of the optical sensor device can be made into four terminals of a high potential side power source VDD, a low potential side power source VSS, an amplifier circuit 1101 output terminal 1104, an IV conversion resistor 1103 and a photodiode 1102 connection terminal, The mounting strength described above can be improved. Further, by using the level shifter, the number of power supplies can be two.
In this embodiment, the amplifier circuit 1101 is described as an operational amplifier (op-amp), but the amplifier circuit 1101 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

  FIG. 12 shows a fourth embodiment of the present invention. The present example is a specific example of the fourth embodiment described above. In this embodiment, two sets of level shift circuits each including an amplifier circuit 1201, a photodiode 1202, TFTs 1205 and 1206, and constant current sources 1207 and 1208 each including a TFT are integrally formed on a sensor substrate. The operation will be described below. The input of the level shift circuit constituted by the N-channel TFT 1205 and the constant current source 1207 is connected to the second electrode of the photodiode 1202 and the first terminal of the IV conversion resistor 1203, and its output is not connected to the amplifier circuit 1201. Connected to the inverting input terminal. An input of the level shift circuit constituted by the N-channel TFT 1206 and the constant current source 1208 is connected to the output terminal 1204 of the amplifier circuit 1201, and its output is connected to the inverting input terminal of the amplifier circuit 1201. Here, the amplifier circuit 1201 functions as a voltage follower. The first electrode of the photodiode 1202 is connected to the low potential side power source VSS. A second terminal of the IV conversion resistor 1203 is connected to the external power supply VBB. Here, the IV conversion resistor 1203 is not formed on the sensor substrate in order to reduce variations in output voltage. However, if the variation is not a problem, the IV conversion resistor 1203 may be formed on the sensor substrate. Is possible.

When light is input to the photodiode 1202, a photocurrent flows from the second electrode of the photodiode 1202 to the first electrode. As a result, a current flows through the IV conversion resistor 1203 and a voltage is generated across the IV conversion resistor 1203.
That is, when light is not input and current does not flow to the photodiode 1202, the same potential as VBB is output to the output terminal 1204. When light is input and current flows to the photodiode 1202, the current is proportional to the amount of current. Thus, the potential of the output terminal 1204 decreases.
In this embodiment, since the driving capability of the amplifier circuit 1201 can be increased, a load can be connected to the output terminal 1204 for driving.
In this embodiment, the connection electrode terminals of the optical sensor device can be made into four terminals of a high potential side power supply VDD, a low potential side power supply VSS, an amplifier circuit 1201 output terminal 1204, an IV conversion resistor 1203 and a photodiode 1202 connection terminal, The mounting strength described above can be improved. Further, by using the level shifter, the number of power supplies can be two.
In this embodiment, the amplifier circuit 1201 is described as an operational amplifier (op-amp), but the amplifier circuit 1201 is not limited to an operational amplifier.
In addition, other photosensor elements are not limited to photodiodes.

  FIG. 14 is an equivalent circuit diagram in the case where an amplifier circuit, particularly an operational amplifier (hereinafter referred to as operational amplifier) circuit, is formed using thin film semiconductor elements, particularly TFTs. This operational amplifier includes a differential circuit composed of TFT 1401 and TFT 1402, a current mirror circuit composed of TFT 1403 and TFT 1404, a constant current source composed of TFT 1405 and TFT 1409, a source grounded circuit composed of TFT 1406, TFT 1407 and TFT 1408. It consists of an idling circuit configured, a source follower circuit configured with TFT 1410 and TFT 1411, and a phase compensation capacitor 1412.

  The operation of the operational amplifier circuit shown in FIG. 14 will be described below. When a + signal is input to the non-inverting input terminal, a constant current source composed of the TFT 1405 is connected to the sources of the TFTs 1401 and 1402 constituting the differential circuit, so that the drain current of the TFT 1401 becomes the drain current of the TFT 1402. The drain current of the TFT 1403 becomes the same as the drain current of the TFT 1402 because the TFT 1404 and the TFT 1403 constitute a current mirror circuit, and the gate potential of the TFT 1406 becomes the difference between the drain current of the TFT 1403 and the drain current of the TFT 1401. It changes in the direction of decreasing. Since the TFT 1406 is a P-channel TFT, when the gate potential of the TFT 1406 decreases, the TFT 1406 operates in a more on direction and the drain current increases. Accordingly, the gate potential of the TFT 1410 increases, and accordingly, the source potential of the TFT 1410, that is, the potential of the output terminal also increases.

  When a negative signal is input to the non-inverting input terminal, the drain current of the TFT 1401 becomes smaller than the drain current of the TFT 1402, and the drain current of the TFT 1403 is the same as the drain current of the TFT 1402. Therefore, the drain current of the TFT 1403 and the TFT 1401 The gate potential of the TFT 1406 changes in an increasing direction due to the difference current between the drain currents. Since the TFT 1406 is a P-channel TFT, when the gate potential of the TFT 1406 increases, the TFT 1406 operates in a direction to turn off and the drain current decreases. Therefore, the gate potential of the TFT 1410 is lowered, and accordingly, the source potential of the TFT 1410, that is, the potential of the output terminal is also lowered. In this way, a signal in phase with the signal at the non-inverting input terminal is output from the output terminal.

  When a + signal is input to the inverting input terminal, the drain current of the TFT 1401 becomes smaller than the drain current of the TFT 1402, and the drain current of the TFT 1403 is the same as the drain current of the TFT 1402. Therefore, the difference current between the drain current of the TFT 1403 and the TFT 1401 As a result, the gate potential of the TFT 1406 changes in a rising direction. Since the TFT 1406 is a P-channel TFT, when the gate potential of the TFT 1406 increases, the TFT 1406 operates in a direction to turn off and the drain current decreases. Therefore, the gate potential of the TFT 1410 is lowered, and accordingly, the source potential of the TFT 1410, that is, the potential of the output terminal is also lowered.

  When a negative signal is input to the inverting input terminal, the drain current of the TFT 1401 becomes larger than the drain current of the TFT 1402, and the drain current of the TFT 1403 is the same as the drain current of the TFT 1402. Due to the difference in drain current, the gate potential of the TFT 1406 changes in a decreasing direction. Since the TFT 1406 is a P-channel TFT, when the gate potential of the TFT 1406 decreases, the TFT 1406 operates in a more on direction and the drain current increases. Accordingly, the gate potential of the TFT 1410 increases, and accordingly, the source potential of the TFT 1410, that is, the potential of the output terminal also increases. In this way, a signal having a phase opposite to that of the inverting input terminal is output from the output terminal.

In this example, the differential circuit is made of an N-channel TFT and the current mirror circuit is made of a P-channel TFT. However, the present invention is not limited to this and may be reversed. Further, the circuit format is not limited to such a circuit format, and any circuit format that satisfies the function as an amplifier circuit can be used.
In addition, this example can be used in combination with the above-described embodiment and examples.

  An example of the structure of the optical sensor device of the present invention will be described below. FIG. 17 shows an optical sensor device in which a photodiode and an amplifier circuit are integrally formed, and is a view seen from the direction of the surface to be attached when mounted on a printed circuit board or the like.

  An amplifier circuit 1702 and a photodiode 1703 are formed on a substrate 1701, and a connection electrode terminal 1704 is formed thereon. The connection electrode terminal 1704 is connected to the amplifier circuit 1702 and the photodiode 1703 through the contact hole 1705.

  An enlarged view of a portion 1706 where the amplifier circuit 1702 and the photodiode 1703 are connected is indicated by a line. The TFT 1707 includes source or drain regions 1708 and 1709, a channel formation region (not shown here), source or drain electrodes 1710 and 1711, and a gate electrode 1712.

  An interlayer insulating film (not shown here) is formed over the gate electrode 1712, and an upper wiring 1713 is connected to the gate electrode 1712 through a contact hole 1714. A first electrode 1715 of the photodiode 1703 is formed over the wiring 1713.

  Next, a state in which the TFT 1707 of the amplifier circuit 1702 and the photodiode 1703 are electrically connected will be described in more detail with reference to a cross-sectional view 18A of an optical sensor device in which a photodiode and an amplifier circuit are integrally formed. . 18A is a cross-sectional view taken along line A-A ′ in FIG. 17, and portions common to FIG. 17 use common reference numerals. A base insulating film 1801 is formed in contact with the substrate 1701, and a TFT 1707 and a photodiode 1703 are formed over the base insulating film 1801.

  The semiconductor layer 1802 is a channel formation region. Source or drain regions 1708 and 1709 are formed on the front and back sides of the channel forming region. A gate electrode 1712 is formed on the semiconductor layer 1802 with a gate insulating film 1803 interposed therebetween, and a first interlayer insulating film 1804 and a second interlayer insulating film 1805 are formed thereon.

  A gate electrode 1712 of the TFT 1707 is connected to a first electrode 1715 of the photodiode 1703 through a contact hole 1714 through a wiring 1713.

  A P-type semiconductor layer 1806 is formed so as to be in contact with the first electrode 1715 of the photodiode 1703, a photoelectric conversion layer 1807 and an N-type semiconductor layer 1808 are stacked thereover, and a photodiode is further formed on the N-channel semiconductor layer 1808. A second electrode 1809 of 1703 is formed. A third interlayer insulating film 1810 is formed over the second electrode 1809 of the photodiode 1703, and the second electrode 1809 of the photodiode 1703 is connected to the connection electrode terminal 1704 through the contact hole 1705.

  As the first electrode 1715 of the photodiode 1703, a light-transmitting and conductive material such as ITO (indium tin oxide) is used so that light incident on the photodiode 1703 is not blocked. it can. As the second electrode 1809 of the photodiode 1703, a light reflecting material such as Ti is used so that light incident from the P-type semiconductor layer 1806 is not absorbed by the photoelectric conversion layer 1807 and is photoelectrically generated. By reflecting light that has passed through the conversion layer 1807 and the N-type semiconductor layer 1808, reflected light can be absorbed again by the photoelectric conversion layer 1807. The P-type semiconductor layer 1806 is a P-type amorphous silicon film (a-Si: H) or a so-called microcrystal semiconductor (μc-Si: H), and the photoelectric conversion layer 1807 is an amorphous silicon film (a-Si). : H), the N-type semiconductor layer 1808 can be formed of an N-type amorphous silicon film (a-Si: H) or a so-called microcrystal semiconductor (μc-Si: H).

  FIG. 18B is a view of the cross section taken along line BB ′ of FIG. 17 as viewed from the A side of line AA ′. In the cross section taken along line BB ′, the third interlayer insulating film 1810 is watermarked. Shows how it looks.

  The TFT 1707 includes a semiconductor layer 1802, source or drain regions 1708 and 1709, source or drain electrodes 1710 and 1711, and a gate electrode 1712, and the gate electrode 1712 extends to the back side of the page, and the first electrode of the photodiode 1703 is formed by a wiring 1713 through a contact hole 1714. 1 electrode 1715. A P-channel semiconductor layer 1806 is formed so as to be in contact with the first electrode 1715 of the photodiode 1703, a photoelectric conversion layer 1807 and an N-channel semiconductor layer 1808 are stacked thereover, and further over the N-channel semiconductor layer 1808. The second electrode 1809 of the photodiode 1703 is formed. A third interlayer insulating film 1810 and a connection electrode terminal 1704 are formed over the second electrode 1809 of the photodiode 1703. The connection electrode terminal 1704 is connected to the second electrode 1809 of the photodiode 1703 through a contact hole (not shown here).

  Note that the present invention is not limited to the configuration of the optical sensor device shown in the sixth embodiment. For example, the amplifier circuit 1702 may include a current mirror circuit instead of an operational amplifier. Further, the optical sensor element is not limited to the above configuration, and may be a polysilicon photodiode, and is not limited to the photodiode, and may be another optical sensor element.

  FIG. 24A shows a seventh embodiment of the present invention. This embodiment is a specific implementation of the fifth embodiment. In this embodiment, an amplifier circuit 2401 and a photodiode 2402 formed of TFTs are integrally formed on a sensor substrate. The operation will be described below. The source region of the TFT of the amplifier circuit 2401 is connected to the external power supply GND, the Y side TFT has N columns in parallel connection, and the drain region of the Y side TFT is connected to the output terminal 2404. The X-side TFT drain region of the amplifier circuit 2401 is connected to the first electrode of the photodiode 2402, and the second electrode is connected to the output terminal 2404.

When light is input to the photodiode 2402, a photocurrent I flows from the second electrode of the photodiode 2402 to the first electrode. As a result, a current I flows through the X-side TFT of the amplifier circuit 2401, and a voltage necessary to flow the current I is generated at the gate.
Since the gate length L and channel width W of the Y-side TFT are equal to those of the X-side TFT, and since each gate of the Y-side TFT is connected to the gate of the X-side TFT, each column of the Y-side TFT has a current I Flows. As a result, when a photocurrent I flows through the photodiode 2402, a current of (1 + N) * I flows through the output terminal 2404.

  In this embodiment, an N-channel TFT has been described, but a P-channel TFT may be used. In the circuit shown in FIG. 24A, the number of parallel connections is increased by N times. However, as shown in FIG. 24B, “channel width W / gate length L” can be increased by N times. Good. In addition, other photosensor elements are not limited to photodiodes.

FIG. 25 shows an eighth embodiment of the present invention. This embodiment is a specific implementation of the sixth embodiment.
In this embodiment, an amplifier circuit 2501 and a photodiode 2502 each composed of a TFT are integrally formed on a sensor substrate. The operation will be described below. The TFTs in the amplifier circuit 2501 are arranged in series on both sides of the X side and the Y side, the source region and the drain region are connected, and the gates are connected in common to form a multi-gate structure. The source region of the low voltage side stage is connected to the external power supply GND, the Y side TFT has N columns of parallel connections, and the drain region of the high voltage side stage of the Y side TFT is connected to the output terminal 2504. Yes. The drain region of the high voltage side stage of the X-side TFT of the amplifier circuit 2501 is connected to the first electrode of the photodiode 2502, and the second electrode is connected to the output terminal 2504.

When light is input to the photodiode 2502, a photocurrent I flows from the second electrode of the photodiode 2502 to the first electrode. As a result, a current I flows through the X-side TFT of the amplifier circuit 2501, and a voltage necessary to flow the current is generated at the gate.
Since the gate length L and channel width W of the Y-side TFT are equal to those of the X-side TFT, and since each gate of the Y-side TFT is connected to the gate of the X-side TFT, each column of the Y-side TFT has a current I Flows. As a result, when the photocurrent I flows through the photodiode 2502, a current of (1 + N) * I flows through the output terminal 2504.

  In this embodiment, an N-channel TFT has been described, but a P-channel TFT may be used. In addition, other photosensor elements are not limited to photodiodes.

FIG. 26 shows a ninth embodiment of the present invention. This example is a specific example of the seventh embodiment.
In this embodiment, an amplifier circuit 2601 and a photodiode 2602 made of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2601 is arranged in series on both the X side and the Y side, the source region and the drain region are connected, the source region of the low voltage side stage is connected to the external power supply GND, and the Y side TFT is N The drain region of the Y side TFT is connected to the output terminal 2604 and the drain region of the high voltage side stage is connected to the output terminal 2604. The drain region of the high voltage side stage of the X-side TFT of the amplifier circuit 2601 is connected to the first electrode of the photodiode 2602, and the second electrode is connected to the output terminal 2604.

When light is input to the photodiode 2602, a photocurrent I flows from the second electrode of the photodiode 2602 to the first electrode. As a result, a current I flows through the X-side TFT of the amplifier circuit 2601 and a voltage necessary to flow the current is generated at the gate.
Since the gate length L and channel width W of the Y-side TFT are equal to those of the X-side TFT, and since each gate of the Y-side TFT is connected to the gate of the X-side TFT, each column of the Y-side TFT has a current I Flows. As a result, when the photocurrent I flows through the photodiode 2602, a current of (1 + N) * I flows through the output terminal 2604.

  In this embodiment, an N-channel TFT has been described, but a P-channel TFT may be used. In addition, other photosensor elements are not limited to photodiodes.

  FIG. 27 shows a tenth embodiment of the present invention. The present example is a specific example of the eighth embodiment. In this embodiment, an amplifier circuit 2701 and a photodiode 2702 made up of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2701 is connected to the Wilson current mirror circuit, the source region of the low voltage side stage is connected to the external power supply GND, the Y side TFT has N columns of parallel connections, and the drain region of the Y side TFT. Is connected to an output terminal 2704. The X-side TFT drain region of the amplifier circuit 2701 is connected to the first electrode of the photodiode 2702, and the second electrode is connected to the output terminal 2704.

When light is input to the photodiode 2702, a photocurrent I flows from the second electrode of the photodiode 2702 to the first electrode. As a result, a current I flows through the X-side TFT of the amplifier circuit 2701, and a voltage necessary to flow the current is generated at the gate.
Since the gate length L and channel width W of the Y-side TFT are equal to those of the X-side TFT, and since each gate of the Y-side TFT is connected to the gate of the X-side TFT, each column of the Y-side TFT has a current I Flows. As a result, when the photocurrent I flows through the photodiode 2702, a current of (1 + N) * I flows through the output terminal 2704.

  In this embodiment, an N-channel TFT has been described, but a P-channel TFT may be used. In addition, other photosensor elements are not limited to photodiodes.

  FIG. 28 shows an eleventh embodiment of the present invention. This example is a specific example of the ninth embodiment. In this embodiment, an amplifier circuit 2801 and a photodiode 2802 made up of TFTs are integrally formed on a sensor substrate. The operation will be described below. The TFT in the amplifier circuit 2801 has an improved Wilson current mirror circuit connection, the source region of the low voltage side stage is connected to the external power supply GND, the Y side TFT has N columns in parallel connection, and the drain of the Y side TFT The region is connected to the output terminal 2804. The X-side TFT drain region of the amplifier circuit 2801 is connected to the first electrode of the photodiode 2802, and the second electrode is connected to the output terminal 2804.

When light is input to the photodiode 2802, a photocurrent I flows from the second electrode of the photodiode 2802 to the first electrode. As a result, a current I flows through the X-side TFT of the amplifier circuit 2801, and a voltage necessary to flow the current is generated at the gate.
Since the gate length L and channel width W of the Y-side TFT are equal to those of the X-side TFT, and since each gate of the Y-side TFT is connected to the gate of the X-side TFT, each column of the Y-side TFT has a current I Flows. As a result, when the photocurrent I flows through the photodiode 2802, a current of (1 + N) * I flows through the output terminal 2804.

  In this embodiment, an N-channel TFT has been described, but a P-channel TFT may be used. In addition, other photosensor elements are not limited to photodiodes.

  As a method for integrally forming a photosensor element such as a photodiode and a TFT on an insulating substrate, a known method can be used. Specifically, the methods described in JP-A-11-125841, JP-A-2002-305296, 305297, etc. may be used.

  The optical sensor device of the present invention configured as described above can be used for luminance adjustment of display portions of various electronic devices. Hereinafter, an electronic device incorporating the photosensor device of the present invention will be described.

  Such electronic devices include video cameras, digital cameras, head mounted displays (goggles type displays), game consoles, car navigation systems, personal computers, personal digital assistants (mobile computers, mobile phones or electronic books, etc.), televisions, and the like. Can be mentioned.

  FIG. 16 shows a personal computer, which includes a main body 3201, a housing 3202, a display portion 3203, a keyboard 3204, an external connection port 3205, a pointing mouse 3206, an optical sensor portion 3207, and the like. Of course, the optical sensor does not need to be provided at the position shown in the figure. For example, if the display unit 3203 includes a double-sided light emitting device and can display on the back side of the figure, the optical sensor unit may be provided on the back side.

  In particular, personal computers have rapidly spread in recent years, and since there are various uses and places where they are used, the brightness of the outside varies depending on the place where they are used, and the brightness required for the display of the personal computer differs. In addition, personal computers often rely on battery power when they are carried around, and reducing power consumption is one of the issues for enabling long-term use. Therefore, by using the optical sensor device of the present invention for the optical sensor unit 3207, it is possible to detect external brightness, and display the display unit 3203 with luminance corresponding to the external brightness, thereby reducing personal power consumption. You can configure the computer. Further, when an EL light-emitting element is used for the display device, the power consumption is suppressed according to the present invention, whereby deterioration of the light-emitting element over time can be suppressed.

  FIG. 15 shows a mobile phone, which includes casings 1501 and 1502, a display unit 1503, an audio input unit 1510, an antenna 1507, operation keys 1505 and 1509, a speaker 1506, a hinge 1508, a battery 1511, an optical sensor unit 1504, and the like. Yes. Of course, the optical sensor need not be provided at the position shown in the figure. For example, if the display unit 1503 is formed of a double-sided light emitting device and can display on the back side of the figure, the optical sensor unit may be provided on the back side.

  Similar to personal computers, mobile phones have been rapidly spreading in recent years, and mobile phones having various functions have been developed. The functions are games, cameras, the Internet, and the like, and these functions are often used using a display device, and are used in various places. Therefore, the brightness of the outside varies depending on the place of use, and the brightness required for display on the mobile phone varies. In addition, since mobile phones often rely on battery power and can be used for a long time, it is one of the problems to reduce power consumption. Therefore, by using the optical sensor device of the present invention for the optical sensor unit 1504, the external brightness is detected, and the display unit 1503 or the operation keys 1505 and 1509 are displayed with the luminance according to the external brightness. A mobile phone with low power consumption can be configured. Further, when an EL light-emitting element is used for the display device, the power consumption is suppressed according to the present invention, whereby deterioration of the light-emitting element over time can be suppressed.

  The electronic apparatus according to the present embodiment can be realized by using any combination of the first to ninth embodiments and the first to thirteenth embodiments.

  The application range of the present invention is extremely wide, and is not limited to the above personal computer and mobile phone, and can be applied to electronic devices in all fields.

The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the conventional optical sensor apparatus. The figure which shows the external shape of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the sensitivity characteristic of a photodiode. The figure which shows the equivalent circuit of the amplifier circuit used for this invention. The figure which shows the mobile telephone which applied the optical sensor apparatus of this invention. The figure which shows the personal computer which applied the optical sensor apparatus of this invention. The figure which shows an example of the structure of the optical sensor apparatus of this invention. The figure which shows an example of the cross-section of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows embodiment of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention. The figure which shows the Example of the optical sensor apparatus of this invention.

Claims (27)

In an optical sensor device having an optical sensor element and an amplifier circuit,
The optical sensor device, wherein the optical sensor element and the amplifier circuit are integrally formed on a substrate. In claim 1,
An optical sensor device, wherein the optical sensor element is constituted by a sensor element using amorphous silicon. In claim 1,
An optical sensor device, wherein the optical sensor element is composed of an amorphous silicon photodiode.     2. The optical sensor device according to claim 1, wherein the optical sensor element is constituted by a sensor element using polysilicon. In claim 1,
An optical sensor device, wherein the optical sensor element is constituted by a polysilicon photodiode. In claims 1 to 5,
An optical sensor device, wherein the amplification circuit is formed of a thin film transistor. In Claims 1 to 6,
The optical sensor device, wherein the amplifier circuit is an operational amplifier. In Claims 1 to 6,
The amplifying circuit is a current mirror circuit. In an optical sensor device having an optical sensor element, an amplifier circuit, and a feedback resistor,
The amplifier circuit is an operational amplifier composed of thin film transistors,
The photosensor element and the amplifier circuit are integrally formed on a substrate,
An optical sensor device comprising the feedback resistor outside the substrate. In an optical sensor device having an optical sensor element, an amplifier circuit, and an IV conversion resistor,
The amplifier circuit is an operational amplifier composed of thin film transistors,
The photosensor element and the amplifier circuit are integrally formed on a substrate,
An optical sensor device comprising the IV conversion resistor outside the substrate. In an optical sensor device having an optical sensor element, an amplifier circuit, and a level shift circuit,
The amplifier circuit and the level shift circuit are composed of thin film transistors,
The optical sensor device, wherein the optical sensor element, the amplifier circuit, and the level shift circuit are integrally formed on a substrate. In claim 11,
The level shift circuit comprises a P-channel type thin film transistor and a constant current source. In claim 11,
The level shift circuit includes an N-channel type thin film transistor and a constant current source. In claims 11 to 13,
4. The photosensor device according to claim 1, wherein the connection electrode terminals on the substrate are four terminals. In claim 14,
An optical sensor device, wherein two of the connection electrode terminals are power supply terminals.   In an optical sensor device having an optical sensor element and an amplifier circuit, the amplifier circuit is a current mirror circuit composed of a thin film transistor, and the optical sensor element and the amplifier circuit are integrally formed on a substrate. Light sensor device.   17. The photosensor device according to claim 16, wherein the photosensor device has a multi-gate structure in which a plurality of gates of the thin film transistors constituting the current mirror circuit are formed.   17. The optical sensor device according to claim 16, wherein the current mirror circuit is configured by cascode connection.   17. The optical sensor device according to claim 16, wherein the current mirror circuit is configured by a Wilson connection.   17. The optical sensor device according to claim 16, wherein the current mirror circuit is configured by an improved Wilson connection.   21. The photosensor device according to claim 16, wherein an amplification factor is selected by changing a number, a gate length, and a channel width of a thin film transistor constituting the current mirror circuit.   The photosensor device according to any one of claims 16 to 21, wherein the current mirror circuit is configured by an N-channel thin film transistor.   The photosensor device according to any one of claims 16 to 21, wherein the current mirror circuit is configured by a P-channel thin film transistor.   17. The optical sensor device according to claim 16, wherein the connection electrode terminals on the substrate are two terminals.   The optical sensor device according to any one of claims 1 to 24, wherein the optical sensor element and the amplifier circuit are integrally formed on a plastic substrate.   The optical sensor device according to any one of claims 1 to 24, wherein the optical sensor element and the amplifier circuit are integrally formed on a glass substrate.   An electronic apparatus comprising the photosensor device according to any one of claims 1 to 26.

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