JP2007329388A - Optical sensor, electro-optical device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor which controls error generation when detecting a light amount of ambient light, and also to provide an electro-optical device and an electronic equipment. <P>SOLUTION: The optical sensor 60 is provided with: the electro-optical device 61 for converting received light into current; a first electrode 621; and a capacitance 62 with a second electrode 622 formed oppositely to the first electrode 621. The source of the electro-optical device 61 is connected with the fourth power supply 912 which outputs selectively either voltage VDD or voltage VSS, the drain of the electro-optical device 61 is connected with the second electrode 622 of the capacity 62, and the first electrode 621 of the capacitance 62 is connected with the third power supply 911 which outputs the voltage VDD. The optical sensor 60 changes the electro-optical device 61 into an on-state. After the voltage VDD is supplied from the fourth power supply 912, the electro-optical device 61 is changed into an off-state, and the voltage VSS is supplied from the fourth power supply 912. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sensor, an electro-optical device, and an electronic apparatus.

  Conventionally, electro-optical devices such as liquid crystal display devices are known. The electro-optical device includes, for example, a liquid crystal panel and a backlight that irradiates light to the liquid crystal panel.

  In such an electro-optical device, the visibility of display changes depending on the ambient brightness of the electro-optical device due to ambient light such as sunlight or illumination light. That is, for example, as the surroundings of the electro-optical device become brighter, the difference between the brightness of the display area of the electro-optical device and the brightness of the surroundings of the electro-optical device becomes smaller, so the visibility of the display of the electro-optical device decreases.

  Therefore, there is an electro-optical device that detects the amount of ambient light using an optical sensor and controls the amount of backlight light emitted from the backlight in accordance with the detected amount of ambient light (see, for example, Patent Document 1). ).

The optical sensor provided in such an electro-optical device has the following configuration, for example.
FIG. 10 is a circuit diagram of an optical sensor 160 included in an electro-optical device according to a conventional example.
The optical sensor 160 includes a first power supply terminal M and a second power supply terminal N, a photoelectric conversion element 161, a capacitor 162, and a switching element 163. Both the photoelectric conversion element 161 and the switching element 163 are configured by thin film transistors (hereinafter referred to as TFT (Thin Film Transistor)).

  A high potential power supply VDD is connected to the first power supply terminal M, and a low potential power supply VSS is connected to the second power supply terminal N.

  The photoelectric conversion element 161 converts the received light into a current. An off-potential power supply VL that outputs a voltage that turns off the photoelectric conversion element 161 is connected to the gate of the photoelectric conversion element 161, and a second power supply terminal N is connected to the source of the photoelectric conversion element 161, and photoelectric conversion is performed. A terminal P is connected to the drain of the element 161.

  The switching element 163 is formed with a light shielding film so as not to receive ambient light, and is turned on and off according to the switching control signal SIG. A control unit 192 that outputs a switching control signal SIG is connected to the gate of the switching element 163, and the first power supply terminal M and the first electrode 1621 of the capacitor 162 are connected to the drain of the switching element 163. A terminal P is connected to the source. The light detection signal Vout is output from this terminal P.

  The capacitor 162 includes a first electrode 1621 and a second electrode 1622 provided to face the first electrode 1621. The first power source terminal M and the drain of the switching element 163 are connected to the first electrode 1621 of the capacitor 162, and the terminal P is connected to the second electrode 1622 of the capacitor 162.

FIG. 11 is a timing chart of the optical sensor 160.
Here, in FIG. 11, a solid line indicates a case where the amount of ambient light is small, and a two-dot chain line indicates a case where the amount of ambient light is large.

First, the case where the amount of ambient light is small will be described below.
At time t41, the switching control signal SIG is set to the potential VH, and the switching element 163 is turned on. Then, since the drain of the photoelectric conversion element 161 and the second electrode 1622 of the capacitor 162 are in conduction with the high potential power supply VDD through the switching element 163 in the on state, the potential VDD is reached. Therefore, the light detection signal Vout output from the terminal P connected to the drain of the photoelectric conversion element 161 becomes the potential VDD.

  At time t42, the switching control signal SIG is set to the potential VL, and the switching element 163 is turned off. Then, the drain of the photoelectric conversion element 161 and the second electrode 1622 of the capacitor 162 are in a non-conduction state with the high potential power supply VDD through the switching element 163 in the off state, and thus hold the potential VDD. Therefore, the light detection signal Vout holds the potential VDD.

  As described above, at time t <b> 42, the source of the photoelectric conversion element 161 is connected to the second power supply terminal N connected to the low potential power supply VSS, and thus is the potential VSS, and the drain of the photoelectric conversion element 161 is The potential is VDD. That is, the source of the photoelectric conversion element 161 has a lower potential than the drain of the photoelectric conversion element 161. Here, the photoelectric conversion element 161 is in an off state since the off-potential power supply VL is connected to the gate. However, the photoelectric conversion element 161 includes a potential difference between the source and drain of the photoelectric conversion element 161 described above, and light reception. A current flows from the drain toward the source based on the ambient light having a small amount of light. Therefore, the drain potential of the photoelectric conversion element 161 gradually decreases from the potential VDD to the source potential VSS of the photoelectric conversion element 161. Therefore, the potential of the light detection signal Vout gradually decreases and becomes the same potential as the reference potential Vref at time t44.

  At time t45, as with time t41, the switching control signal SIG is set to the potential VH, and the switching element 163 is turned on. Then, like the time t41, the light detection signal Vout becomes the potential VDD.

Next, the case where the amount of ambient light is large will be described below.
At time t41, the switching control signal SIG is set to the potential VH, and the switching element 163 is turned on. Then, as in the case where the amount of ambient light is small, the light detection signal Vout becomes the potential VDD.

  At time t42, the switching control signal SIG is set to the potential VL, and the switching element 163 is turned off. Then, as in the case where the amount of ambient light is small, the light detection signal Vout holds the potential VDD.

  As described above, at time t42, as in the case where the amount of ambient light is small, the source of the photoelectric conversion element 161 is connected to the second power supply terminal N connected to the low potential power supply VSS. The drain of the photoelectric conversion element 161 is at the potential VDD. That is, the source of the photoelectric conversion element 161 has a lower potential than the drain of the photoelectric conversion element 161. Here, the photoelectric conversion element 161 is in an off state since the off-potential power supply VL is connected to the gate. Based on the ambient light with a large amount of light, a larger current flows from the drain to the source than when the amount of ambient light is small. For this reason, the drain potential of the photoelectric conversion element 161 is drastically lowered from the potential VDD to the source potential VSS of the photoelectric conversion element 161 as compared with the case where the amount of ambient light is small. Therefore, the potential of the light detection signal Vout is rapidly decreased as compared with the case where the amount of ambient light is small, and becomes the same potential as the reference potential Vref at time t43.

  At time t45, as with time t41, the switching control signal SIG is set to the potential VH, and the switching element 163 is turned on. Then, like the time t41, the light detection signal Vout becomes the potential VDD.

  As described above, in the optical sensor 160, as the amount of ambient light decreases, the time at which the potential of the light detection signal Vout becomes the same potential as the reference potential Vref is delayed. As the amount of ambient light increases, the light detection signal Vout increases. The time when the potential becomes equal to the reference potential Vref is earlier.

Therefore, in the electro-optical device including the optical sensor 160 described above, the amount of ambient light can be detected by measuring the time when the potential of the light detection signal Vout becomes the same potential as the reference potential Vref.
JP 2006-29832 A

  By the way, in the switching element 163, when the temperature rises or a part of the environmental light that cannot be blocked by the light shielding film is received, even in the off state, like the photoelectric conversion element 161, from the drain toward the source. Current flows. Then, due to this current, the potential of the drain of the photoelectric conversion element 161 changes, and the potential of the light detection signal Vout also changes.

  That is, in the optical sensor 160, the potential of the light detection signal Vout varies due to the switching element 163, and an error may occur when detecting the amount of ambient light.

  An object of the present invention is to provide an optical sensor, an electro-optical device, and an electronic apparatus that can suppress occurrence of an error when detecting the amount of ambient light.

  The optical sensor of the present invention is an optical sensor including a photoelectric conversion element that converts received light into an electrical signal, and a capacitor, and includes a first power source and a second power source that output a predetermined voltage, and the photoelectric sensor. And a control unit that outputs a control signal for controlling on / off of the conversion element, wherein one end of the capacitor is connected to the first power source, and the photoelectric conversion element is connected to the other end of the capacitor The second power source is connected to the other end of the photoelectric conversion element, and after the photoelectric conversion element is turned on by the control unit, the photoelectric conversion element is turned off by the control unit, The voltage output from at least one of the first power supply and the second power supply is varied.

  According to this invention, the photoelectric conversion element is turned on, and one end and the other end of the photoelectric conversion element are set to predetermined potentials. Then, the photoelectric conversion element was turned off, and the voltage output from at least one of the first power supply and the second power supply was varied, so that one end and the other end of the photoelectric conversion element were set to different potentials. Here, although the photoelectric conversion element is in an off state, the photoelectric conversion element is in accordance with the amount of light received based on the potential difference between the one end and the other end of the photoelectric conversion element described above and the received light. An electrical signal is generated. For this reason, the electric potential of one end or the other end of the photoelectric conversion element varies until the same electric potential is obtained. Therefore, for example, the time when the potential at which one or the other end of the photoelectric conversion element changes becomes a predetermined potential is measured, or one end or the other of the photoelectric conversion element after a predetermined period has elapsed since the photoelectric conversion element is turned off. The amount of ambient light can be detected by measuring the potential that fluctuates at the edges.

  In addition, according to the present invention, the photoelectric conversion element converts received light into an electric signal, and the switching element according to the conventional example described above is turned on and off. Therefore, the optical sensor can be miniaturized by the amount that does not include the switching element. Further, since the switching element is not provided, an electric signal is generated in the switching element in the off state, and the electric signal does not change the potential at one end or the other end of the photoelectric conversion element. It is possible to suppress the occurrence of an error when detecting the amount of light.

  An optical sensor according to the present invention is an optical sensor including a photoelectric conversion element that converts received light into an electrical signal, and a capacitor, a third power source that outputs a third voltage, and the third voltage. Or a fourth power source that selectively outputs any one of a fourth voltage having a lower potential than the third voltage, and a control unit that outputs a control signal for controlling on / off of the photoelectric conversion element. One end of the capacitor is connected to the third power source, one end of the photoelectric conversion element is connected to the other end of the capacitor, and the fourth power source is connected to the other end of the photoelectric conversion element. The control unit turns on the photoelectric conversion element, and after selectively outputting the third voltage from the fourth power source, the control unit turns off the photoelectric conversion element, The fourth voltage is selectively output from the fourth power source. Characterized in that it.

According to the present invention, the photoelectric conversion element is turned on, the third voltage is selectively output from the fourth power source, and the potentials at one end and the other end of the photoelectric conversion element are based on the third voltage. The potential was 3. Then, the photoelectric conversion element is turned off, and the fourth voltage is selectively output from the fourth power source, so that the potential at the other end of the photoelectric conversion element is lowered to the fourth potential based on the fourth voltage. It was.
As described above, one end of the photoelectric conversion element has a higher potential than the other end of the photoelectric conversion element. Here, although the photoelectric conversion element is in an off state, the photoelectric conversion element is in accordance with the amount of light received based on the potential difference between the one end and the other end of the photoelectric conversion element described above and the received light. An electrical signal is generated. For this reason, the potential at one end of the photoelectric conversion element varies in accordance with the amount of received light up to the potential at the other end of the photoelectric conversion element.
According to the present invention, there are effects similar to those described above.

  The optical sensor of the present invention is an optical sensor that includes a photoelectric conversion element that converts received light into an electrical signal, and a capacitor, and includes a fifth power source that outputs a fifth voltage, and the fifth voltage. Or a sixth power source that selectively outputs any one of the sixth voltages having a higher potential than the fifth voltage, and a control unit that outputs a control signal for controlling on / off of the photoelectric conversion element. One end of the capacitor is connected to the fifth power source, one end of the photoelectric conversion element is connected to the other end of the capacitor, and the sixth power source is connected to the other end of the photoelectric conversion element. The control unit turns on the photoelectric conversion element, and after selectively outputting the fifth voltage from the sixth power supply, the control unit turns off the photoelectric conversion element, The sixth voltage is selectively output from the sixth power source. Characterized in that it.

According to the present invention, the photoelectric conversion element is turned on, the fifth voltage is selectively output from the sixth power source, and the potentials at one end and the other end of the photoelectric conversion element are based on the fifth voltage. The potential was 5. Then, the photoelectric conversion element is turned off, and the sixth voltage is selectively output from the sixth power source to raise the potential of the other end of the photoelectric conversion element to the sixth potential based on the sixth voltage. It was.
As described above, the potential of one end of the photoelectric conversion element is lower than that of the other end of the photoelectric conversion element. Here, although the photoelectric conversion element is in an off state, the photoelectric conversion element is in accordance with the amount of light received based on the potential difference between the one end and the other end of the photoelectric conversion element described above and the received light. An electrical signal is generated. For this reason, the potential at one end of the photoelectric conversion element varies in accordance with the amount of received light up to the potential at the other end of the photoelectric conversion element.
According to the present invention, there are effects similar to those described above.

  The optical sensor of the present invention is an optical sensor including a photoelectric conversion element that converts received light into an electrical signal, and a capacitor, a seventh power source that outputs a seventh voltage, and the seventh voltage. Or an eighth power source that selectively outputs any of the eighth voltages having a potential higher than the seventh voltage, and a control unit that outputs a control signal for controlling on / off of the photoelectric conversion element. One end of the capacitor is connected to the eighth power source, one end of the photoelectric conversion element is connected to the other end of the capacitor, and the seventh power source is connected to the other end of the photoelectric conversion element. The control unit turns on the photoelectric conversion element, and after selectively outputting the seventh voltage from the eighth power source, the control unit turns off the photoelectric conversion element, The eighth voltage is selectively output from the eighth power source. Characterized in that it.

According to this invention, the photoelectric conversion element is turned on, the potentials at one end and the other end of the photoelectric conversion element and the other end of the capacitor are set to the seventh potential based on the seventh voltage, and the eighth A seventh voltage was selectively output from the power source, and the potential at one end of the capacitor was set to a seventh potential based on the seventh voltage. Then, in the capacitor, the potential difference between one end and the other end is “0”.
Then, the photoelectric conversion element was turned off, and the eighth voltage was selectively output from the eighth power source to raise the potential at one end of the capacitor to the eighth potential. Here, in the capacitor, when the potential at one end of the capacitor varies, the potential at the other end of the capacitor also varies, and the potential difference “0” between the one end and the other end of the capacitor is to be held. Therefore, the potential at the other end of the capacitor increases by the amount corresponding to the increase in the potential at one end of the capacitor. Therefore, the potential at one end of the photoelectric conversion element increases by the amount that the potential at the other end of the capacitor increases.
As described above, one end of the photoelectric conversion element has a higher potential than the other end of the photoelectric conversion element. Here, although the photoelectric conversion element is in an off state, the photoelectric conversion element is in accordance with the amount of light received based on the potential difference between the one end and the other end of the photoelectric conversion element described above and the received light. An electrical signal is generated. For this reason, the potential at one end of the photoelectric conversion element varies in accordance with the amount of received light up to the potential at the other end of the photoelectric conversion element.
According to the present invention, there are effects similar to those described above.

  In the optical sensor according to the aspect of the invention, the photoelectric conversion element is turned on by the control unit and the photoelectric conversion element is turned off by the control unit after selectively outputting the eighth voltage from the eighth power source. Preferably, the seventh voltage is selectively output from the eighth power source.

According to this invention, the photoelectric conversion element is turned on, the potentials at one end and the other end of the photoelectric conversion element and the other end of the capacitor are set to the seventh potential based on the seventh voltage, and the eighth The eighth voltage was selectively output from the power source, and the potential at one end of the capacitor was set to the eighth potential based on the eighth voltage. Then, in the capacitor, a potential difference is generated between one end and the other end.
Then, the photoelectric conversion element was turned off, and the seventh voltage was selectively output from the eighth power source, so that the potential at one end of the capacitor was lowered to the seventh potential. Here, in the capacitor, when the potential at one end of the capacitor varies, the potential at the other end of the capacitor also varies, and the potential difference between the one end and the other end of the capacitor is to be held. Therefore, the potential at the other end of the capacitor is decreased by the amount corresponding to the decrease in the potential at one end of the capacitor. Therefore, the potential at one end of the photoelectric conversion element is lowered by the amount that the potential at the other end of the capacitor is lowered.
As described above, the potential of one end of the photoelectric conversion element is lower than that of the other end of the photoelectric conversion element. Here, although the photoelectric conversion element is in an off state, the photoelectric conversion element is in accordance with the amount of light received based on the potential difference between the one end and the other end of the photoelectric conversion element described above and the received light. An electrical signal is generated. For this reason, the potential at one end of the photoelectric conversion element varies in accordance with the amount of received light up to the potential at the other end of the photoelectric conversion element.
According to the present invention, there are effects similar to those described above.

An electro-optical device according to the present invention includes the above-described optical sensor.
According to the present invention, since the optical sensor is provided in the electro-optical device, gradation display can be performed according to the amount of ambient light. In addition, since the optical sensor is downsized, the electro-optical device can be downsized.

An electronic apparatus according to an aspect of the invention includes the above-described electro-optical device.
According to the present invention, there are effects similar to those described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of embodiments and modifications, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
<First Embodiment>
FIG. 1 is a block diagram of an electro-optical device according to a first embodiment of the invention.
The electro-optical device 1 includes a liquid crystal panel AA, a control circuit 90 that drives the liquid crystal panel AA, and a backlight 31 that irradiates light to the liquid crystal panel AA. The electro-optical device 1 uses the light from the backlight 31 to perform transmissive display.

  The liquid crystal panel AA includes a display area A having a plurality of pixels 50, a scanning line driving circuit 11 and a data line driving circuit 21 that are provided around the display area A and drive the pixels 50, and an optical sensor 60. Prepare.

  The backlight 31 is provided on the back surface of the liquid crystal panel AA, and is composed of, for example, a cold cathode fluorescent tube (CCFL), an LED (light emitting diode), or electroluminescence (EL), and transmits light to the pixels 50 of the liquid crystal panel AA. Supply.

  The control circuit 90 includes a power supply circuit 91 that supplies power to the liquid crystal panel AA, a panel control circuit 92 that outputs a panel control signal for controlling the scanning line driving circuit 11, the data line driving circuit 21, and the optical sensor 60, and a back surface. And a backlight control circuit 93 that outputs a backlight control signal for controlling the light 31.

  The power supply circuit 91 supplies driving power necessary for driving the scanning line driving circuit 11, the data line driving circuit 21, the optical sensor 60, and the like to the liquid crystal panel AA. The power supply circuit 91 selects either the third power supply 911 (see FIG. 2) that outputs the voltage VDD as the third voltage and the voltage VSS as the fourth voltage that is lower than the voltage VDD or the voltage VDD. And a fourth power source 912 (see FIG. 2) for outputting the power.

  The panel control circuit 92 supplies a control signal for sequentially selecting and scanning the plurality of scanning lines Y to the scanning line driving circuit 11, and synchronizes the operation of the scanning line driving circuit 11 to the data line driving circuit 21. Thus, an image signal based on display image data supplied from a host device (not shown) is supplied. The panel control circuit 92 includes a control unit (not shown) that outputs a control signal SIG for controlling on / off of a photoelectric conversion element 61 (see FIG. 2) described later.

  The backlight control circuit 93 supplies a backlight control signal for controlling the light amount of the backlight 31 to the backlight 31 based on the light detection signal Vout output from the optical sensor 60.

Hereinafter, the configuration of the liquid crystal panel AA will be described in detail.
The liquid crystal panel AA includes 320 rows of scanning lines Y1 to Y320, and 240 columns of data lines X1 to X240 provided so as to intersect the scanning lines Y1 to Y320, and each scanning line Y and each data line. Pixels 50 are provided at the intersections of X. A common line 30 is provided substantially parallel to the scanning line Y.

  The pixel 50 includes a TFT 51, a pixel electrode 55, a common electrode 56 facing the pixel electrode 55, and a storage capacitor 53 having one end connected to the pixel electrode 55 and the other end connected to the common line 30. The pixel electrode 55 and the common electrode 56 sandwich a liquid crystal (not shown) that is a dielectric as an electro-optic material, and constitute a pixel capacitor.

  The scanning line Y is connected to the gate of the TFT 51, the data line X is connected to the source of the TFT 51, and the pixel electrode 55 and the storage capacitor 53 are connected to the drain of the TFT 51. Therefore, the TFT 51 is turned on when a selection voltage is applied from the scanning line Y, and the data line X, the pixel electrode 55, and the storage capacitor 53 are brought into conduction.

  The scanning line driving circuit 11 sequentially supplies a selection voltage for turning on the TFT 51 to the plurality of scanning lines Y. For example, when a selection voltage is supplied to a certain scanning line Y, all the TFTs 51 connected to the scanning line Y are turned on, and all the pixels 50 related to the scanning line Y are selected.

The data line driving circuit 21 supplies an image signal to each data line X, and writes an image voltage based on the image signal to the pixel electrode 55 via the TFT 51 in the on state.
Here, the data line driving circuit 21 inverts the polarity of the image signal supplied to the data line X every frame period with the voltage of the common electrode 56 as a reference. Specifically, for example, a positive image signal is supplied to the data line X in one frame period, and a negative image signal is supplied to the data line X in the next one frame period.

The above electro-optical device 1 operates as follows.
That is, by sequentially supplying a selection voltage from the scanning line driving circuit 11 to the scanning lines Y1 to Y320 in 320 rows, all the TFTs 51 related to the scanning lines Y are sequentially turned on, and all the scanning lines Y are related to each other. Pixels 50 are selected sequentially. In synchronization with the selection of the pixels 50, an image signal is supplied from the data line driving circuit 21 to the data line X. Then, an image signal is supplied to all the pixels 50 selected by the scanning line driving circuit 11 from the data line driving circuit 21 via the data line X and the on-state TFT 51, and an image voltage based on this image signal is applied to the pixel electrode. 55 is written. As a result, a potential difference is generated between the pixel electrode 55 and the common electrode 56, and an image voltage is applied to the liquid crystal.

  When an image voltage is applied to the liquid crystal, the alignment of the liquid crystal changes, and the light from the backlight 31 that transmits the liquid crystal changes, so that gradation display is performed.

FIG. 2 is a circuit diagram of the optical sensor 60.
The optical sensor 60 includes a photoelectric conversion element 61 and a capacitor 62. The photoelectric conversion element 61 is composed of a TFT.

  The photoelectric conversion element 61 converts the received light into a current. A panel control circuit 92 is connected to the gate of the photoelectric conversion element 61, a fourth power source 912 is connected to the source of the photoelectric conversion element 61, and a terminal P is connected to the drain of the photoelectric conversion element 61. .

  The capacitor 62 includes a first electrode 621 and a second electrode 622 provided to face the first electrode 621. A third power source 911 is connected to the first electrode 621 of the capacitor 62, and a terminal P is connected to the second electrode 622 of the capacitor 62.

FIG. 3 is a timing chart of the optical sensor 60.
Here, in FIG. 3, V4 is a voltage output from the fourth power supply 912.

  First, at time t1, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61 is turned on, and the voltage VDD is selectively output as the voltage V4 from the fourth power supply 912.

Then, since the first electrode 621 of the capacitor 62 is connected to the third power source 911, the potential is VDD, and the second electrode 622 of the capacitor 62 is connected to the fourth power source 912 via the photoelectric conversion element 61 in the on state. And is in a conductive state, and thus becomes the potential VDD.
In addition, since the source of the photoelectric conversion element 61 is connected to the fourth power supply 912, the potential becomes VDD, and the drain of the photoelectric conversion element 61 is in conduction with the fourth power supply 912 through the photoelectric conversion element 61 in the on state. Therefore, the potential is VDD. Therefore, the light detection signal Vout output from the terminal P connected to the drain of the photoelectric conversion element 61 becomes the potential VDD.

  Next, at time t2, the switching control signal SIG is set to the potential VL, the photoelectric conversion element 61 is turned off, and the voltage VSS is selectively output as the voltage V4 from the fourth power supply 912.

Then, since the first electrode 621 of the capacitor 62 is connected to the third power supply 911, the potential VDD is held, and the second electrode 622 of the capacitor 62 is connected to the fourth power supply via the photoelectric conversion element 61 in the off state. Since it is in a non-conductive state with 912, the potential VDD is held.
In addition, since the source of the photoelectric conversion element 61 is connected to the fourth power supply 912, the potential is lowered to the potential VSS, and the drain of the photoelectric conversion element 61 is connected to the fourth power supply 912 via the photoelectric conversion element 61 in the off state. Since it is in a non-conduction state, the potential VDD which is the same potential as the second electrode 622 of the capacitor 62 is held. Therefore, the light detection signal Vout holds the potential VDD.

  As described above, at time t2, the source of the photoelectric conversion element 61 is the potential VSS, and the drain of the photoelectric conversion element 61 is the potential VDD. That is, the potential of the source of the photoelectric conversion element 61 is lower than that of the drain of the photoelectric conversion element 61. Here, although the photoelectric conversion element 61 is in an OFF state, the photoelectric conversion element 61 receives received ambient light based on the above-described potential difference between the source and drain of the photoelectric conversion element 61 and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the drain of the photoelectric conversion element 61 decreases from the potential VDD to the potential VSS of the source of the photoelectric conversion element 61 according to the amount of received ambient light. Therefore, the potential of the light detection signal Vout decreases according to the amount of received ambient light, and becomes the same potential as the reference potential Vref at time t3.

  Next, at time t4, similarly to time t1, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61 is turned on, and the voltage VDD is selectively output from the fourth power supply 912 as the voltage V4.

  Then, like the time t1, the light detection signal Vout becomes the potential VDD.

  The backlight control circuit 93 described above measures the time until the potential of the light detection signal Vout decreases from VDD to Vref, that is, the time from time t2 to time t3. If the time from time t2 to t3 is shorter than the predetermined time, it is determined that the amount of ambient light is large, and the amount of light of the backlight 31 is made larger than the predetermined amount. On the other hand, if the time from time t2 to t3 is longer than the predetermined time, it is determined that the light amount of the ambient light is small, and the light amount of the backlight 31 is made smaller than the predetermined light amount.

According to this embodiment, there are the following effects.
(1) First, the photoelectric conversion element 61 was turned on, and the voltage VDD was selectively output from the fourth power source 912, so that the source and drain potentials of the photoelectric conversion element 61 were set to the same potential VDD. Next, the photoelectric conversion element 61 was turned off, and the voltage VSS was selectively output from the fourth power supply 912 to reduce the source potential of the photoelectric conversion element 61 to VSS.
As described above, the source of the photoelectric conversion element 61 has a lower potential than the drain of the photoelectric conversion element 61. Here, although the photoelectric conversion element 61 is in an OFF state, the photoelectric conversion element 61 receives received ambient light based on the above-described potential difference between the source and drain of the photoelectric conversion element 61 and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the drain of the photoelectric conversion element 61 decreases from the potential VDD to the potential VSS of the source of the photoelectric conversion element 61 according to the amount of received ambient light.
Therefore, the backlight control circuit 93 measures the time until the drain potential of the photoelectric conversion element 61 decreases from VDD to Vref, and the amount of ambient light can be detected based on the measured time.

  (2) Since the TFT is one of the photoelectric conversion elements 61, the potential of the drain of the photoelectric conversion element 61 does not fluctuate due to an electric signal generated by another TFT, and the amount of ambient light is detected. It is possible to suppress the occurrence of errors.

  (3) The photoelectric conversion element 61 converts the received ambient light into a current and turns it on and off. Therefore, since the number of TFTs is one less than when two TFTs, a TFT that converts received ambient light into current and a TFT that turns on and off, are provided, the photosensor 60 can be downsized.

  (4) Since the optical sensor 60 provided in the electro-optical device 1 is downsized, the electro-optical device 1 can be downsized.

  (5) Since the light sensor 60 is provided in the electro-optical device 1 and the light amount of the backlight 31 is controlled by the backlight control circuit 93 according to the light amount of the ambient light, the visibility of the display in the electro-optical device 1 is improved. it can.

Second Embodiment
FIG. 4 is a circuit diagram of an optical sensor 60A according to the second embodiment of the present invention.
The optical sensor 60A includes a photoelectric conversion element 61A and a capacitor 62A. The photoelectric conversion element 61A is composed of a TFT.

  Here, the power supply circuit 91 includes a fifth power supply 913 and a sixth power supply 914 instead of the third power supply 911 and the fourth power supply 912 in FIG. The fifth power supply 913 outputs the voltage VSS as the fifth voltage, and the sixth power supply 914 selectively outputs either the voltage VSS or the voltage VDD as the sixth voltage having a higher potential than the voltage VSS. .

  The photoelectric conversion element 61A converts the received light into a current. A panel control circuit 92 is connected to the gate of the photoelectric conversion element 61A, a terminal P is connected to the source of the photoelectric conversion element 61A, and a sixth power source 914 is connected to the drain of the photoelectric conversion element 61A. .

  The capacitor 62A includes a first electrode 621A and a second electrode 622A provided to face the first electrode 621A. A fifth power source 913 is connected to the first electrode 621A of the capacitor 62A, and a terminal P is connected to the second electrode 622A of the capacitor 62A.

FIG. 5 is a timing chart of the optical sensor 60A.
Here, in FIG. 5, V6 is a voltage output from the sixth power source 914.

  First, at time t11, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61A is turned on, and the voltage VSS is selectively output from the sixth power source 914 as the voltage V6.

Then, since the first electrode 621A of the capacitor 62A is connected to the fifth power source 913, it is at the potential VSS, and the second electrode 622A of the capacitor 62A is connected to the sixth power source 914 via the photoelectric conversion element 61A in the on state. And is in a conductive state, and thus becomes the potential VSS.
Further, since the source of the photoelectric conversion element 61A is in conduction with the sixth power source 914 through the photoelectric conversion element 61A in the on state, the potential becomes VSS, and the drain of the photoelectric conversion element 61A is connected to the sixth power source 914. Since it is connected, it becomes the potential VSS. Therefore, the light detection signal Vout output from the terminal P connected to the source of the photoelectric conversion element 61A becomes the potential VSS.

  Next, at time t12, the switching control signal SIG is set to the potential VL, the photoelectric conversion element 61A is turned off, and the voltage VDD is selectively output as the voltage V6 from the sixth power source 914.

Then, since the first electrode 621A of the capacitor 62A is connected to the fifth power supply 913, the potential VSS is maintained, and the second electrode 622A of the capacitor 62A is connected to the sixth power supply via the photoelectric conversion element 61A in the off state. Since it is in a non-conductive state with 914, the potential VSS is held.
Further, since the source of the photoelectric conversion element 61A is in a non-conduction state with the sixth power source 914 via the photoelectric conversion element 61A in the off state, the potential VSS which is the same potential as the second electrode 622A of the capacitor 62A is held. The drain of the photoelectric conversion element 61A is connected to the sixth power source 914, and thus rises to VDD. Therefore, the light detection signal Vout holds the potential VSS.

  As described above, at the time t12, the source of the photoelectric conversion element 61A is the potential VSS, and the drain of the photoelectric conversion element 61A is the potential VDD. That is, the potential of the source of the photoelectric conversion element 61A is lower than that of the drain of the photoelectric conversion element 61A. Here, although the photoelectric conversion element 61A is in an off state, the photoelectric conversion element 61A receives the ambient light received based on the potential difference between the source and drain of the photoelectric conversion element 61A and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the source of the photoelectric conversion element 61A rises from the potential VSS to the potential VDD of the drain of the photoelectric conversion element 61A according to the amount of received ambient light. Therefore, the potential of the light detection signal Vout increases according to the amount of received ambient light, and becomes the same potential as the reference potential Vref at time t13.

  Next, at time t14, similarly to time t11, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61A is turned on, and the voltage VSS is selectively output from the sixth power supply 914 as the voltage V6.

  Then, as at time t11, the light detection signal Vout becomes the potential VSS.

According to this embodiment, there are the following effects.
(6) First, the photoelectric conversion element 61A was turned on, and the voltage VSS was selectively output from the sixth power source 914, so that the potential of the source and drain of the photoelectric conversion element 61A was set to VSS of the same potential. Next, the photoelectric conversion element 61A was turned off, and the voltage VDD was selectively output from the sixth power source 914 to increase the drain potential of the photoelectric conversion element 61A to VDD.
As described above, the potential of the source of the photoelectric conversion element 61A is lower than that of the drain of the photoelectric conversion element 61A. Here, although the photoelectric conversion element 61A is in an off state, the photoelectric conversion element 61A receives the ambient light received based on the potential difference between the source and drain of the photoelectric conversion element 61A and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the source of the photoelectric conversion element 61A rises from the potential VSS to the potential VDD of the drain of the photoelectric conversion element 61A according to the amount of received ambient light.
Therefore, since the backlight control circuit 93 measures the time until the potential of the source of the photoelectric conversion element 61A rises from VSS to Vref, the amount of ambient light can be detected based on the measured time.

<Third Embodiment>
FIG. 6 is a circuit diagram of an optical sensor 60B according to the third embodiment of the present invention.
The optical sensor 60B includes a photoelectric conversion element 61B and a capacitor 62B. The photoelectric conversion element 61B is configured by a TFT.

  Here, the power supply circuit 91 includes a seventh power supply 915 and an eighth power supply 916 instead of the third power supply 911 and the fourth power supply 912 in FIG. The seventh power supply 915 outputs the voltage VSS as the seventh voltage, and the eighth power supply 916 selectively outputs either the voltage VSS or the voltage VDD as the eighth voltage having a higher potential than the voltage VSS. .

  The photoelectric conversion element 61B converts the received light into a current. A panel control circuit 92 is connected to the gate of the photoelectric conversion element 61B, a seventh power source 915 is connected to the source of the photoelectric conversion element 61B, and a terminal P is connected to the drain of the photoelectric conversion element 61B. .

  The capacitor 62B includes a first electrode 621B and a second electrode 622B provided to face the first electrode 621B. An eighth power source 916 is connected to the first electrode 621B of the capacitor 62B, and a terminal P is connected to the second electrode 622B of the capacitor 62B.

FIG. 7 is a timing chart of the optical sensor 60B.
Here, in FIG. 7, V8 is a voltage output from the eighth power supply 916.

  First, at time t21, the switching control signal SIG is set to the potential VH to turn on the photoelectric conversion element 61B, and the voltage VSS is selectively output from the eighth power source 916 as the voltage V8.

Then, since the first electrode 621B of the capacitor 62B is connected to the eighth power source 916, it becomes the potential VSS, and the second electrode 622B of the capacitor 62B is connected to the seventh power source 915 via the photoelectric conversion element 61B in the on state. Since it is in a conductive state, it becomes the potential VSS. Therefore, in the capacitor 62B, the potential difference between the first electrode 621B and the second electrode 622B is “0”.
In addition, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, it is at the potential VSS, and the drain of the photoelectric conversion element 61B is electrically connected to the seventh power source 915 via the on-state photoelectric conversion element 61B. Since it is in a state, it becomes the potential VSS. Therefore, the light detection signal Vout output from the terminal P connected to the drain of the photoelectric conversion element 61B becomes the potential VSS.

  Next, at time t22, the switching control signal SIG is set to the potential VL to turn off the photoelectric conversion element 61B, and the eighth power supply 916 selectively outputs the voltage VDD as the voltage V8.

Then, since the first electrode 621B of the capacitor 62B is connected to the eighth power source 916, it rises to the potential VDD. Here, in the capacitor 62B, when the potential of the first electrode 621B varies, the potential of the second electrode 622B also varies to try to maintain the potential difference “0” between the first electrode 621B and the second electrode 622B. For this reason, the potential of the second electrode 622B of the capacitor 62B rises to VDD. Accordingly, since the drain of the photoelectric conversion element 61B is connected to the second electrode 622B of the capacitor 62B, the potential rises to VDD. Therefore, the light detection signal Vout becomes the potential VDD.
Further, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, the potential VSS is held.

  As described above, at the time t22, the source of the photoelectric conversion element 61B is the potential VSS, and the drain of the photoelectric conversion element 61B is the potential VDD. That is, the potential of the source of the photoelectric conversion element 61B is lower than that of the drain of the photoelectric conversion element 61B. Here, although the photoelectric conversion element 61B is in an off state, the photoelectric conversion element 61B has received ambient light based on the potential difference between the source and drain of the photoelectric conversion element 61B and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the drain of the photoelectric conversion element 61B decreases from the potential VDD to the potential VSS of the source of the photoelectric conversion element 61B according to the amount of received ambient light. Therefore, the potential of the light detection signal Vout decreases according to the amount of received ambient light, and becomes the same potential as the reference potential Vref at time t23.

  Next, at time t24, similarly to time t21, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61B is turned on, and the voltage VSS is selectively output from the eighth power source 916 as the voltage V8.

  Then, as at time t21, the light detection signal Vout becomes the potential VSS.

According to this embodiment, there are the following effects.
(7) First, the photoelectric conversion element 61B is turned on, and the voltage VSS is selectively output from the eighth power source 916, so that the potential difference between the first electrode 621B and the second electrode 622B of the capacitor 62B is “0”. did. Next, the photoelectric conversion element 61B was turned off, and the voltage VDD was selectively output from the eighth power source 916 to raise the potential of the first electrode 621B of the capacitor 62B to VDD. Here, in the capacitor 62B, when the potential of the first electrode 621B of the capacitor 62B varies, the potential of the second electrode 622B of the capacitor 62B also varies, and the potential difference “0” between the first electrode 621B and the second electrode 622B of the capacitor 62B. Try to hold. Therefore, the potential of the second electrode 622B of the capacitor 62B is increased by the potential of the first electrode 621B of the capacitor 62B, that is, the potential difference (VDD−VSS), and becomes the potential VDD. Therefore, the potential of the drain of the photoelectric conversion element 61B increases to the potential VDD by increasing the potential of the second electrode 622B of the capacitor 62B, that is, by the potential difference (VDD−VSS). On the other hand, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, it is at the potential VSS.
As described above, the potential of the source of the photoelectric conversion element 61B is lower than that of the drain of the photoelectric conversion element 61B. Here, although the photoelectric conversion element 61B is in an off state, the photoelectric conversion element 61B has received ambient light based on the potential difference between the source and drain of the photoelectric conversion element 61B and the received ambient light. A current corresponding to the amount of light flows from the drain toward the source. For this reason, the potential of the drain of the photoelectric conversion element 61B decreases from the potential VDD to the potential VSS of the source of the photoelectric conversion element 61B according to the amount of received ambient light.
Therefore, the backlight control circuit 93 measures the time until the potential of the drain of the photoelectric conversion element 61B decreases from VDD to Vref, and the amount of ambient light can be detected based on the measured time.

<Fourth embodiment>
FIG. 8 is a timing chart of the optical sensor 60B according to the fourth embodiment of the present invention.
In the timing chart of FIG. 8, the operation of the optical sensor 60B of FIG. 6 is different from that of the timing chart of FIG.

  First, at time t31, the switching control signal SIG is set to the potential VH to turn on the photoelectric conversion element 61B, and the eighth power supply 916 selectively outputs the voltage VDD as the voltage V8.

Then, since the first electrode 621B of the capacitor 62B is connected to the eighth power source 916, the potential becomes VDD, and the second electrode 622B of the capacitor 62B is connected to the seventh power source 915 via the on-state photoelectric conversion element 61B. Since it is in a conductive state, it becomes the potential VSS. Therefore, in the capacitor 62B, a potential difference (VDD−VSS) is generated between the first electrode 621B and the second electrode 622B.
In addition, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, it is at the potential VSS, and the drain of the photoelectric conversion element 61B is electrically connected to the seventh power source 915 via the on-state photoelectric conversion element 61B. Since it is in a state, it becomes the potential VSS. Therefore, the light detection signal Vout output from the terminal P connected to the drain of the photoelectric conversion element 61B becomes the potential VSS.

  Next, at time t32, the switching control signal SIG is set to the potential VL, the photoelectric conversion element 61B is turned off, and the voltage VSS is selectively output as the voltage V8 from the eighth power source 916.

Then, since the first electrode 621B of the capacitor 62B is connected to the eighth power source 916, it drops to the potential VSS. Here, in the capacitor 62B, when the potential of the first electrode 621B varies, the potential of the second electrode 622B also varies, and an attempt is made to hold the potential difference (VDD−VSS) between the first electrode 621B and the second electrode 622B. For this reason, the potential of the second electrode 622B of the capacitor 62B decreases to (2VSS−VDD). Therefore, since the drain of the photoelectric conversion element 61B is connected to the second electrode 622B of the capacitor 62B, the potential decreases to (2VSS−VDD). Therefore, the light detection signal Vout becomes a potential (2VSS−VDD).
Further, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, the potential VSS is held.

  As described above, at the time t32, the source of the photoelectric conversion element 61B is the potential VSS, and the drain of the photoelectric conversion element 61B is the potential (2VSS−VDD). That is, the source of the photoelectric conversion element 61B has a higher potential than the drain of the photoelectric conversion element 61B. Here, although the photoelectric conversion element 61B is in an off state, the photoelectric conversion element 61B has received ambient light based on the potential difference between the source and drain of the photoelectric conversion element 61B and the received ambient light. A current corresponding to the amount of light flows from the source toward the drain. Therefore, the potential of the drain of the photoelectric conversion element 61B rises from the potential (2VSS−VDD) to the potential VSS of the source of the photoelectric conversion element 61B according to the amount of received ambient light. Therefore, the potential of the light detection signal Vout increases according to the amount of received ambient light, and becomes the same potential as the reference potential Vref at time t33.

  Next, at time t34, similarly to time t31, the switching control signal SIG is set to the potential VH, the photoelectric conversion element 61B is turned on, and the voltage VDD is selectively output from the eighth power supply 916 as the voltage V8.

  Then, as at time t31, the potential of the light detection signal Vout becomes VSS.

According to this embodiment, there are the following effects.
(8) First, the photoelectric conversion element 61B is turned on, and the voltage VDD is selectively output from the eighth power source 916, so that the potential difference between the first electrode 621B and the second electrode 622B of the capacitor 62B is (VDD−VSS). ). Next, the photoelectric conversion element 61B was turned off, and the voltage VSS was selectively output from the eighth power source 916, so that the potential of the first electrode 621B of the capacitor 62B was lowered to VSS. Here, in the capacitor 62B, when the potential of the first electrode 621B of the capacitor 62B varies, the potential of the second electrode 622B of the capacitor 62B also varies, and the potential difference (VDD) between the first electrode 621B and the second electrode 622B of the capacitor 62B. -VSS). Therefore, the potential of the second electrode 622B of the capacitor 62B is decreased by the potential of the first electrode 621B of the capacitor 62B, that is, the potential difference (VDD−VSS), and becomes the potential (2VSS−VDD). Therefore, the potential of the drain of the photoelectric conversion element 61B is decreased by the potential of the second electrode 622B of the capacitor 62B, that is, the potential difference (VDD−VSS), and becomes the potential (2VSS−VDD). On the other hand, since the source of the photoelectric conversion element 61B is connected to the seventh power source 915, it is at the potential VSS.
As described above, the source of the photoelectric conversion element 61B has a higher potential than the drain of the photoelectric conversion element 61B. Here, although the photoelectric conversion element 61B is in an off state, the photoelectric conversion element 61B has received ambient light based on the potential difference between the source and drain of the photoelectric conversion element 61B and the received ambient light. A current corresponding to the amount of light flows from the source toward the drain. Therefore, the potential of the drain of the photoelectric conversion element 61B rises from the potential (2VSS−VDD) to the potential VSS of the source of the photoelectric conversion element 61B according to the amount of received ambient light.
Therefore, the backlight control circuit 93 measures the time until the potential of the drain of the photoelectric conversion element 61B decreases from (2VSS−VDD) to Vref. Therefore, the amount of ambient light can be detected based on the measured time.

<Modification>
Note that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within a scope in which the object of the present invention can be achieved are included in the present invention.
For example, in the first embodiment described above, the electro-optical device 1 performs transmissive display. However, the present invention is not limited to this, and transmissive display that uses light from the backlight 31, natural light, and room light. A transflective display having both a reflective display using ambient reflected light and the like may be performed.

  In each of the above embodiments, 320 rows of scanning lines Y and 240 columns of data lines X are provided. However, the present invention is not limited to this. For example, 480 rows of scanning lines Y and 640 columns of rows are provided. And a data line X.

  In each of the above-described embodiments, in order to detect the amount of ambient light, the time at which the potential of the light detection signal Vout output from the terminal P is lower than the reference potential Vref is measured, but the present invention is not limited to this. For example, the potential of the photodetection signal Vout output from the terminal P may be measured after a predetermined period has elapsed since the photoelectric conversion element 61 is turned off by setting the potential of the switching control signal SIG to VL.

  In each of the above-described embodiments, the light amount of the backlight 31 is controlled according to the light amount of the ambient light. However, the present invention is not limited to this, and for example, an image signal may be adjusted.

  In each of the above-described embodiments, the polarity of the image signal supplied to the data line X is inverted every frame period. However, the present invention is not limited to this. For example, the polarity may be inverted every horizontal scanning period.

<Application example>
Next, an electronic apparatus to which the electro-optical device 1 according to the above-described embodiment is applied will be described.
FIG. 9 is a perspective view illustrating a configuration of a mobile phone to which the electro-optical device 1 is applied. The cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 1. By operating the scroll button 3002, the screen displayed on the electro-optical device 1 is scrolled.

The electronic apparatus to which the electro-optical device 1 is applied is not limited to the one shown in FIG. 9, but a personal computer, a portable information terminal, a digital still camera, a liquid crystal television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation system Examples of the apparatus include a device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a video phone, a POS terminal, and a touch panel. The electro-optical device described above can be applied as a display unit of these various electronic devices. By applying to these, the backlight brightness is optimized by the external light, the optimal visibility is obtained regardless of the viewing environment, and unnecessary brightness can be prevented, thus reducing power consumption Can also be planned.
Note that the present light sensor is not intended to be limited to the use of backlight dimming, but may be used, for example, to make so-called gamma setting of display gradation variable by external light.

1 is a block diagram illustrating a configuration of an electro-optical device according to a first embodiment of the invention. FIG. FIG. 3 is a circuit diagram of an optical sensor provided in the electro-optical device. 3 is a timing chart of an optical sensor included in the electro-optical device. FIG. 6 is a circuit diagram of an optical sensor included in an electro-optical device according to a second embodiment of the invention. 3 is a timing chart of an optical sensor included in the electro-optical device. FIG. 6 is a circuit diagram of an optical sensor provided in an electro-optical device according to a third embodiment of the invention. 3 is a timing chart of an optical sensor included in the electro-optical device. 10 is a timing chart of an optical sensor included in an electro-optical device according to a fourth embodiment of the invention. It is a perspective view which shows the structure of the mobile telephone to which the electro-optical device mentioned above is applied. It is a circuit diagram of the optical sensor with which the electro-optical apparatus which concerns on a prior art example is provided. 3 is a timing chart of an optical sensor included in the electro-optical device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electro-optical apparatus, 11 ... Scanning line drive circuit, 21 ... Data line drive circuit, 31 ... Backlight, 50 ... Pixel, 60 ... Photosensor, 61, 61A, 61B ... Photoelectric conversion element, 62, 62A, 62B ... Capacitance, 621, 621A, 621B ... first electrode, 622,622A, 622B ... second electrode, 90 ... control circuit, 91 ... power supply circuit, 911 ... third power supply, 912 ... fourth power supply, 913 ... fifth power supply, 914: Sixth power source, 915: Seventh power source, 916: Eighth power source, 92: Panel control circuit (control unit), 93: Backlight control circuit, 3000: Mobile phone (electronic device).

Claims (7)

An optical sensor comprising a photoelectric conversion element that converts received light into an electrical signal, and a capacitor,
A first power source and a second power source for outputting a predetermined voltage;
A control unit that outputs a control signal for controlling on / off of the photoelectric conversion element,
One end of the capacitor is connected to the first power source,
The photoelectric conversion element is connected to the other end of the capacitor,
The second power source is connected to the other end of the photoelectric conversion element,
After turning on the photoelectric conversion element by the control unit,
An optical sensor, wherein the photoelectric conversion element is turned off by the control unit, and a voltage output from at least one of the first power supply and the second power supply is changed. An optical sensor comprising a photoelectric conversion element that converts received light into an electrical signal, and a capacitor,
A third power source for outputting a third voltage;
A fourth power source that selectively outputs either the third voltage or a fourth voltage having a lower potential than the third voltage;
A control unit that outputs a control signal for controlling on / off of the photoelectric conversion element,
One end of the capacitor is connected to the third power source,
One end of the photoelectric conversion element is connected to the other end of the capacitor,
The fourth power source is connected to the other end of the photoelectric conversion element,
After turning on the photoelectric conversion element by the control unit and selectively outputting the third voltage from the fourth power supply,
The photoelectric sensor is turned off by the control unit, and the fourth voltage is selectively output from the fourth power source. An optical sensor comprising a photoelectric conversion element that converts received light into an electrical signal, and a capacitor,
A fifth power source for outputting a fifth voltage;
A sixth power source that selectively outputs either the fifth voltage or a sixth voltage having a higher potential than the fifth voltage;
A control unit that outputs a control signal for controlling on / off of the photoelectric conversion element,
One end of the capacitor is connected to the fifth power source,
One end of the photoelectric conversion element is connected to the other end of the capacitor,
The sixth power source is connected to the other end of the photoelectric conversion element,
After turning on the photoelectric conversion element by the control unit and selectively outputting the fifth voltage from the sixth power supply,
The photoelectric sensor is turned off by the control unit, and the sixth voltage is selectively output from the sixth power source. An optical sensor comprising a photoelectric conversion element that converts received light into an electrical signal, and a capacitor,
A seventh power source for outputting a seventh voltage;
An eighth power source that selectively outputs either the seventh voltage or an eighth voltage having a higher potential than the seventh voltage;
A control unit that outputs a control signal for controlling on / off of the photoelectric conversion element,
One end of the capacitor is connected to the eighth power source,
One end of the photoelectric conversion element is connected to the other end of the capacitor,
The seventh power source is connected to the other end of the photoelectric conversion element,
After turning on the photoelectric conversion element by the control unit and selectively outputting the seventh voltage from the eighth power source,
The photoelectric sensor is turned off by the controller, and the eighth voltage is selectively output from the eighth power source. The optical sensor according to claim 4,
After turning on the photoelectric conversion element by the control unit and selectively outputting the eighth voltage from the eighth power source,
The photoelectric sensor is turned off by the control unit, and the seventh voltage is selectively output from the eighth power source.   An electro-optical device comprising the optical sensor according to claim 1. An electronic apparatus comprising the electro-optical device according to claim 6.

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