JP2009135185A - Optical sensor element, method of driving optical sensor element, display device, and method of driving display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sensor element which can be improved in photodetection sensitivity, and to provide a driving method thereof. <P>SOLUTION: The optical sensor element S having a semiconductor layer 7 provided with a p-type region 7p and an n-type region 7n in a state where an i-type region 7i used as a photodetection portion is interposed is characterized in that two control electrodes G1 and G2 are provided electrically independently on both side faces of the semiconductor layer 7 at positions across the i-type region 7i with gate insulating films 5 and 9 interposed therebetween. When an electric signal is read out of the i-type region 7i, the two control electrodes G1 and G2 are controlled independently of each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical sensor element having a PIN type semiconductor structure, a driving method of the optical sensor element, a display device including the optical sensor element, and a driving method thereof.

  In recent years, in a flat display device such as a liquid crystal display device or an organic EL display device, a screen sensor such as a touch panel or a pen input or a backlight luminance control is provided by providing a photosensor element in or near the display screen. Multi-functionalization such as realization is progressing. As an optical sensor element provided in such a display device, a PIN thin film diode using a silicon (Si) thin film is often used because of a simple manufacturing process.

  An optical sensor element having a PIN type thin-film diode structure has a configuration in which a p-type region and an n-type region are provided in a semiconductor layer (silicon thin film) with an i-type region adjacent to and sandwiching the i-type region. It is used as. In addition, in the optical sensor element having such a configuration, a configuration is proposed in which a control electrode is provided in an i-type region via an insulating film for the purpose of preventing leakage current.

With such a configuration, the threshold value of the bias voltage when current starts to flow through the PIN diode can be controlled by the gate voltage applied to the control electrode. This also prevents a leak current from being generated in the photosensor element to which a bias voltage higher than the gate voltage is not applied in the state of being irradiated with light.
(For example, refer to Patent Document 1 below).

JP 2004-119719 A

  By the way, in a display device provided with the photosensor element having the above-described configuration, in order to obtain high-quality image, it is required to reduce the pitch between pixel openings and improve the pixel aperture ratio. For this reason, an optical sensor element provided between the pixel openings or outside the display area is required to reduce the occupied area, and light sensitivity with a finer element is required.

  Accordingly, the present invention provides an optical sensor element capable of improving the light receiving sensitivity and a driving method thereof, and further, by using this optical sensor element, the pixel aperture ratio is reduced by reducing the area occupied by the optical sensor element. An object of the present invention is to provide a display device capable of improving the above.

  In order to achieve such an object, the present invention provides an optical sensor element including a semiconductor layer in which a p-type region and an n-type region are provided with an i-type region used as a light-receiving portion interposed therebetween. The surface is characterized in that two control electrodes are arranged electrically and independently at a position sandwiching the i-type region via a gate insulating film.

  The present invention is also a method for driving the optical sensor element having such a configuration, and is characterized in that when an electric signal is read from the i-type region, the two control electrodes are independently controlled.

  In the optical sensor element having such a configuration, by applying different potentials to the two control electrodes provided above and below the i-type region, hole-electron pairs generated by light reception in the i-type region are reduced. It can be separated in the film thickness direction. As a result, the holes are moved in the anode (p-type region) direction and the electrons are moved in the cathode (n-type region) direction with the holes and electrons separated in the film thickness direction in the i-type region. it can. For this reason, the probability that electron / hole pairs generated by light reception recombine when moving in the i-type region is reduced, and the current extraction efficiency is improved.

  The display device of the present invention includes display pixels arranged in a matrix in a display region on a substrate and a photosensor element provided on the substrate, and the photosensor having the above-described configuration is provided as the photosensor element. It is characterized by using elements.

  In the display device having such a configuration, by providing the photosensor element that can improve the current extraction efficiency as described above, the area occupied by the photosensor element can be reduced and the pixel aperture can be enlarged.

  As described above, according to the present invention, it is possible to improve the light receiving sensitivity of the optical sensor element by improving the current extraction efficiency. By providing such an optical sensor element, it is possible to reduce the area occupied by the optical sensor element in the display device and improve the image quality by improving the pixel aperture ratio.

  Embodiments of the present invention will be described below in detail in the order of an optical sensor element, an optical sensor element driving method, a display device, and a display apparatus driving method.

<Configuration of optical sensor element>
FIG. 1 is a schematic cross-sectional view showing a configuration of an optical sensor element to which the present invention is applied. The optical sensor element S shown in this figure is an optical sensor element S having a so-called PIN type thin film diode structure, and is configured as follows.

  That is, the first control electrode G1 made of a light reflective material such as aluminum is wired on the substrate 1, and the gate insulating film 5 is provided so as to cover the first control electrode G1. The gate insulating film 5 is preferably light transmissive. On the gate insulating film 5, a semiconductor layer 7 made of polysilicon, an oxide semiconductor, or the like is formed in a pattern so as to straddle the first control electrode G1. The semiconductor layer 7 has a p-type region 7p on one side of the first control electrode G1 and an n-type region 7n on the other side of the first control electrode G1. In addition, the silicon thin film 7 portion that overlaps the first control electrode G1 is provided with a light receiving portion (i-type region) 7i in which the impurity concentration is kept low. That is, the semiconductor layer 7 has a configuration in which the p-type region 7p and the n-type region 7n are provided adjacent to the light receiving portion (i-type region) 7i.

  Further, an interlayer insulating film 9 made of a light transmissive material is provided so as to cover the semiconductor layer 7, and on the interlayer insulating film 9, a p-type region 7p and an n-type region 7n are connected via a connection hole. Each connected wiring 11 is provided. Further, a planarizing insulating film 13 made of a light transmissive material is provided on the interlayer insulating film 9 so as to cover these wirings 11. The planarizing insulating film 13 is provided with an opening window 13a having a wide opening on the light receiving portion 7i and having the interlayer insulating film 9 as a bottom surface.

  On the planarization insulating film 13, the second control electrode G2 is provided. The second control electrode G2 is disposed at the bottom of the opening window 13 so as to face the light receiving portion 7i with the interlayer insulating film 9 as a gate insulating film. As a result, the first control electrode G1 and the second control electrode G2 are disposed on both side surfaces of the semiconductor layer 7 with the i-type region 7i interposed therebetween via the gate insulating film formed of the gate insulating film 5 and the interlayer insulating film 9. It is in an arranged state. The first control electrode G1 and the second control electrode G2 are electrically wired independently.

  In addition, here, the second control electrode G2 is made of a material having optical transparency to the light received by the light receiving unit 7i, and is made of a transparent conductive material such as ITO. The second control electrode G2 made of such a material is preferably provided as a thin film in order to ensure light transmittance. Further, in order to ensure the conductivity of the second control electrode G2, the second control electrode G2 may be connected to the wiring 11 below the planarization insulating film 13.

  In the optical sensor element S configured as described above, the light h irradiated from the second control electrode G2 side passes through the second control electrode G2 and the interlayer insulating film (gate insulating film) 9 and is received by the light receiving unit 7i. And photoelectrically converted. Then, by applying a reverse bias to the PIN type thin film diode structure having the p-type region 7p as an anode and the n-type region 7n as a cathode, the electric charge photoelectrically converted and accumulated in the light receiving portion (i-type region 7i) It can be read out as an electrical signal.

  As described above, when an electric signal is read out from the light receiving unit (i-type region) 7i, driving for independently controlling the two control electrodes G1 and G2 is performed as described below.

  The optical sensor element S may be configured to receive not only the light from the second control electrode G2 side but also the light from the second control electrode G1 side. In this case, the substrate 1, the first control electrode G1, and the gate insulating film 5 are all made of a light transmissive material, so that the light irradiated from the substrate 1 side is photoelectrically converted and read by the light receiving unit 7i. Further, a configuration may be adopted in which light irradiated from both the first control electrode G1 and the second control electrode G2 is photoelectrically converted by the light receiving unit 7i and read.

<Driving method of optical sensor element-1>
Next, a method of driving the optical sensor element S will be described based on the configuration diagram of FIG. 1 and the schematic diagram of the band structure of FIG. 2A 'is a band structure in the direction of the p-type region 7p-n-type region 7n in the semiconductor layer, and FIG. 2B-B' is a band structure in the direction of the second control electrode 2G-first control electrode G1 in the semiconductor layer. Structure.

  As described above, when an electric signal is read from the light receiving portion (i-type region) 7i of the photosensor element S, the PIN-type thin film diode structure having the p-type region 7p as an anode and the n-type region 7n as a cathode is used. Apply reverse bias. That is, as a read voltage applied between the p-type region 7p and the n-type region 7n, a negative anode potential Vac is applied to the p-type region 7p, and a positive cathode potential Vc is applied to the n-type region 7n. Then, a reverse bias of a certain magnitude is applied as a read voltage (threshold voltage), so that an on state in which a current suddenly flows between the p-type region 7p (anode) and the n-type region 7n (cathode) is entered. The electrical signal is taken out.

  At this time, as shown in FIG. 3, (1) in the state where the first control electrode G1 and the second control electrode G2 are not controlled and no voltage is applied, the anode potential Vac (reverse bias) is smaller than that in the on state. ) Also causes a leakage current. On the other hand, (2) by controlling the voltage to be applied only to the first control electrode G1 (or the second control electrode G2), the anode potential Vac that is smaller than the ON state (threshold voltage) is set. Leakage current in the range can be prevented.

  Further, (3) by controlling the voltage applied to both the first control electrode G1 and the second control electrode G2, the current value in the on state is controlled. In this case, for example, a voltage having a reverse polarity may be applied to the first control electrode G1 and the second control electrode G2. As an example, when the anode potential Vac of the p-type region 7p = −7 V and the cathode potential Vc of the n-type region 7n = 0 V, the potential Vg1 of the first control electrode G1 = −5 V, the potential Vg2 of the second control electrode G2 = + 5V.

  In this way, for example, by applying a reverse polarity voltage to the first control electrode G1 and the second control electrode G2, an electric field in the film thickness direction is formed in the light receiving portion (i-type region) 7i. By such an electric field, hole / electron pairs generated by photoelectric conversion in the light receiving portion (i-type region) 7i are separated in the film thickness direction in the light receiving portion 7i. And it can prevent being recombined and consumed in the light-receiving part 7i. Thereby, it is possible to improve the extraction efficiency of the electric signal, that is, to improve the sensitivity.

Moreover, by the electric field formed in the light receiving portion (i-type region) 7i, regardless of the impurity concentration of the semiconductor layer 7, to control the Fermi level E _F between bandgap Ec-Ev in the light receiving portion 7i be able to. This makes it possible to easily generate a hole-electron pair by photoelectric conversion even by irradiation with light having a long wavelength with low energy, and an improvement in sensitivity due to this can be expected.

<Driving method of optical sensor element-2>
Another example of the method for driving the optical sensor element S will be described.

  Here, as described above, when a reverse bias is applied to the p-type region 7p (anode) and the n-type region 7n (cathode) and an electric signal is extracted, as shown in FIG. By performing control to apply a voltage to both the electrode G1 and the second control electrode G2, a read voltage (threshold value) applied to the p-type region and the n-type region when reading an electric signal from the i-type region 7i. Voltage). As an example of this control, when the anode potential Vac of the p-type region 7p = −7 V and the cathode potential Vc of the n-type region 7n = 0 V, the potential Vg1 of the first control electrode G1 = −10 V, and the second control electrode G2 The potential Vg2 = + 5V.

  Here, (1) in a state where the first control electrode G1 and the second control electrode G2 are not controlled and no voltage is applied, a leakage current flows even at an anode potential Vac (reverse bias) smaller than the on state. . On the other hand, (2) by controlling the voltage to be applied only to the first control electrode G1 (or the second control electrode G2), the anode potential Vac that is smaller than the ON state (threshold voltage) is set. Leakage current in the range can be prevented.

  Further, as described above, (3) ′ an anode potential smaller than that in an on state (threshold voltage) by performing control to apply a voltage to both the first control electrode G1 and the second control electrode G2. While preventing leakage current in the range of Vac, it is possible to read an electric signal with a smaller reading voltage (threshold voltage).

<Configuration of display device>
Next, a configuration of a display device using the above-described optical sensor element S will be described. FIG. 5 is a diagram showing the overall configuration of the display device 20 according to the present invention, which is characterized by being configured using the above-described optical sensor element. The display device 20 includes a display panel 21, a backlight 22, a display drive circuit 23, a light receiving drive circuit 24, an image processing unit 25, and an application program execution unit 26.

  The display panel 21 is composed of a liquid crystal panel (LCD (Liquid Crystal Display)) in which a plurality of pixels are arranged in a matrix over the entire surface in a central display area 21a, and performs predetermined operations based on display data while performing line sequential operation. It has a function (display function) for displaying images such as figures and characters. As will be described later, the display area 21 a is provided with a sensor function (imaging function) for detecting an object in contact with or close to the display surface of the display panel 21.

  The backlight 22 is a light source of the display panel 21 and is formed by arranging a plurality of light emitting diodes in a plane, for example. As will be described later, the backlight 22 is configured to quickly turn on / off the light emitting diodes at a predetermined timing synchronized with the operation timing of the display panel 21. In particular, in the present invention, as described later, the first feature is that the backlight 22 emits ultraviolet light together with visible light for image display.

  The display drive circuit 23 is a circuit that drives the display panel 21 (drives a line-sequential operation) so that an image based on display data is displayed on the display panel 21 (to perform a display operation). .

  The light receiving drive circuit 24 is a circuit that drives the display panel 21 (drives line-sequential operation) so that light reception data can be obtained on the display panel 21 (so that an object is imaged). The light reception data at each pixel is stored in the frame memory 23a, for example, in units of frames, and is output to the image processing unit 25 as a captured image.

  The image processing unit 25 performs predetermined image processing (arithmetic processing) based on the captured image output from the light receiving drive circuit 24, and information (position coordinate data, object shape, Data related to size) is detected and acquired.

  The application program execution unit 26 executes processing corresponding to predetermined application software based on the detection result by the image processing unit 25. For example, the display data includes the position coordinates of the detected object in the display panel 21. What is displayed on the top. The display data generated by the application program execution unit 26 is supplied to the display drive circuit 23.

<Circuit configuration of display area>
FIG. 6 is a diagram showing a circuit configuration in the display area 21 a of the display panel 21.

  As shown in FIG. 5, a plurality of pixel portions 31 and a plurality of sensor portions 32 are arranged in the display area 21a.

  In the display area 21a, the pixel unit 31 is disposed at each intersection of a plurality of scanning lines 31a wired in the horizontal direction and a plurality of signal lines 31b wired in the vertical direction. Each pixel unit 31 is provided with a thin film transistor (TFT) Tr as a switching element, for example.

  The thin film transistor Tr has a gate connected to the scanning line 31a, one source / drain connected to the signal line 31b, and the other source / drain connected to the pixel electrode 31c. Each pixel unit 31 is provided with a common electrode 31d that applies a common potential Vcom to all the pixel units 31, and a liquid crystal layer LC is sandwiched between the pixel electrode 31c and the common electrode 31d. .

  Then, the thin film transistor Tr is turned on / off based on a drive signal supplied via the scanning line 31a, and a pixel voltage is applied to the pixel electrode 31c based on a display signal supplied from the signal line 31b in the on state. In addition, the liquid crystal layer LC is driven by the electric field between the pixel electrode 31c and the common electrode 31d.

  On the other hand, the sensor unit 32 may be disposed at a predetermined portion in the display area 21 a and may be provided corresponding to each pixel unit 31 or may be provided at a ratio of one to the plurality of pixel units 31. . The sensor unit 32 is provided with an optical sensor element S having a PIN type thin film diode structure including two control electrodes having the configuration described with reference to FIG. The optical sensor element S is characterized in that it is configured using the same layer as the thin film transistor Tr of the pixel portion 31 as will be described in detail below. The components of the optical sensor element S will be described with the same reference numerals as in FIG.

  Each photosensor element S has an n-type region (cathode) 7n connected to a power supply line (Vdd) 32a and a p-type region (anode) 7p connected to a capacitive element Cs. One of the two control electrodes G1, G2 provided on both surfaces of each photosensor element S is connected to the scanning line 31a, and the other is connected to the control line 32b.

  The sensor unit 32 is provided with two transistors Tr1 and Tr2 connected via a source / drain. One transistor Tr1 has a gate connected to the p-type region (anode) 7p of the optical sensor element S and the capacitor element Cs, and a source / drain connected to the power supply line (Vdd) 32a. The other transistor Tr2 has a gate connected to the read control electrode 32c and a source / drain connected to the signal output electrode 32d. The other electrode of the capacitive element Cs is connected to the power supply line (Vss) 32e.

  In the photosensor element S, charges corresponding to the amount of received light are accumulated in the capacitive element Cs while being reset by a reset switch (not shown). The charge accumulated in the capacitive element Cs is supplied to the signal output electrode 32d by a signal supplied from the read control electrode 32c and is output to the outside.

<Configuration of display panel>
FIG. 7 is a schematic cross-sectional view of the display panel 21 for explaining the configuration of the thin film transistor Tr arranged in the pixel unit 31 and the configuration of the photosensor element S arranged in the sensor unit 32. Components similar to those described in FIGS. 1 and 5 are denoted by the same reference numerals.

  As shown in this figure, the pixel portion 31 is provided with a bottom gate type thin film transistor Tr as a pixel driving switching element, while the sensor portion 32 is provided with the two control electrodes described with reference to FIG. An optical sensor element S having a PIN type thin film diode structure, a thin film transistor (Tr1, Tr2) and a capacitor element (Cs) (not shown) are provided. In particular, the thin film transistor Tr and the optical sensor element S are characterized by being configured as follows using a semiconductor layer 7 made of polysilicon, an oxide semiconductor, or the like formed in the same process. .

  That is, the thin film transistor Tr includes a substrate 1 made of a light transmissive material as a first substrate 1, and includes a gate electrode 3g made of the same layer as the first control electrode G1 of the photosensor element S on the first substrate 1. A gate insulating film 5 is provided so as to cover this. On the gate insulating film 5, a semiconductor layer 7 made of the same layer as the semiconductor layer 7 of the photosensor element S is patterned in a state of covering the gate electrode 3 g and covering both sides thereof. The semiconductor layer 7 is provided with a source / drain 7sd into which impurities are introduced on both sides of the gate electrode 3g. In the semiconductor layer 7, a portion overlapping with the gate electrode 3g is used as an active layer 7ch in which a channel portion is formed. Further, an LDD into which impurities are introduced at a low concentration is provided between the source / drain 7sd and the active layer 7ch.

  In the thin film transistor Tr and the optical sensor element S having such a configuration, the gate electrode 3g and the first control electrode G1 are made of the same layer, and the semiconductor layer 7 is made of the same layer formed in the same process. In the peripheral region of the display region 21a on the first substrate 1, a CMOS drive circuit configuration including p-channel and n-channel thin film transistors Tr is provided in the same layer as the thin film transistor Tr of the display region 21a. In the impurity introduction for forming these source / drains 7sd, the p-type region 7p and the n-type region 7n of the photosensor element S are formed.

  An interlayer insulating film 9 made of a light transmissive material is provided so as to cover the thin film transistor Tr and the optical sensor element S as described above. On the interlayer insulating film 9, a plurality of wirings 11 connected to the source / drain 7sd of the thin film transistor Tr and the p-type region 7p and the n-type region 7n of the photosensor element S are provided. The circuit shown in FIG. 6 is configured by using the first control line G1, the gate electrode 3g, the semiconductor layer 7, and wiring using the same layer as the conductive layer such as the wiring 11.

  In addition, a planarization insulating film 13 is provided so as to cover the above wiring 11, and a pixel electrode 31 c made of the same layer as the second control electrode G <b> 2 is provided on the planarization insulating film 13. The pixel electrode 31 c is made of a transparent conductive material, and is connected to the wiring 11 drawn from the source / drain 7 sd of the thin film transistor Tr through a connection hole provided in the planarization insulating film 13.

  An alignment film (not shown) is provided so as to cover the pixel electrode 31c, and the upper portion of the first substrate 1 is configured.

  On the other hand, the second substrate 41 is disposed opposite to the formation surface side of the pixel electrode 31c in the first substrate 1 as described above. The second substrate 41 is made of a light-transmitting material, and a color filter layer 42 in which each color filter is patterned for each pixel is provided on the surface facing the pixel electrode 31c as necessary. A common electrode 31d made of a transparent conductive material and an alignment film (not shown) are provided so as to cover the color filter layer 42. A liquid crystal layer LC is sandwiched between the alignment films of the two substrates 1-41 together with spacers (not shown).

  Further, the display panel 21 is configured by disposing deflection plates 43 and 44 outside the substrate 1-41.

<Driving method of display device>
The driving of the display device 20 having the configuration described above with reference to FIGS. 5 to 7 passes through the polarizing plate 43 and reaches the liquid crystal layer LC among the light emitted from the backlight 22 on the first substrate 1 side. The polarized light is polarized into a predetermined state by switching the liquid crystal layer LC by driving the pixel electrode 31c. Then, only the light polarized in the same direction as the polarizing plate 44 on the second substrate 41 side passes through the polarizing plate 44 and is displayed as display light.

  When an object such as a finger or a stylus pen approaches from the outside of the second substrate 41 on the display screen side, the light sensor element S detects the shadow of external light from the object, or the light from the backlight. Is reflected by an object and detected by the optical sensor element S. Then, the light detected by the optical sensor element S is read out as an electrical signal, thereby detecting the approach position of the finger or the stylus pen on the display screen to perform imaging.

  In particular, when the light detected by the photosensor element S is taken out as an electrical signal, as described above, the voltage applied to both the first control electrode G1 and the second control electrode G2 of the photosensor element S, The amount of electric signal read from the light sensor element S is controlled to improve the extraction efficiency of the electric signal, and when the electric signal is read from the light sensor element S, the p-type regions (anodes) 7p and n of the light sensor element S are read. A read voltage (threshold voltage) applied to the mold region (cathode) 7n is controlled.

  In the display device 20 having the above-described configuration, the photosensor element S in which the sensitivity is improved as described above is used as the photosensor element S, thereby miniaturizing the photosensor element S in the display region 21a. be able to.

  Thereby, the area occupied by the sensor unit 31 provided with the photosensor element S can be reduced, and the pixel aperture ratio can be improved by enlarging the pixel unit 32. Therefore, it is possible to achieve high image quality in the display device 20 with a sensor function (imaging function).

In addition, the optical sensor element S forms an electric field in the light receiving portion (i-type region) 7i by controlling the voltage applied to both the first control electrode G1 and the second control electrode G2. regardless of the impurity concentration, it is capable of controlling the Fermi level E _F between bandgap Ec-Ev in the light receiving portion 7i. For this reason, even if the impurity concentration in the semiconductor layer 7 is designed in accordance with the characteristics of the thin film transistor Tr, the optical sensor element S is desired by the voltage applied to the first control electrode G1 and the second control electrode G2. It is possible to control the characteristics. Therefore, the sensitivity of the photosensor element S can be maintained regardless of the characteristics of the thin film transistor using the same layer as the photosensor element S. This also makes it possible to reduce the area occupied by the sensor unit 31 provided with the optical sensor element S and to improve the image quality of the display device 20 with a sensor function (imaging function).

  In the above embodiment, the liquid crystal display device is exemplified as the display device having the sensor function (imaging function). However, the display device is limited to the liquid crystal display device as long as the optical sensor element is arranged in the display area. In other words, the same effect can be obtained by using the optical sensor element S having the configuration of the present invention.

<Other examples of display device>
As another example of the display device using the optical sensor element S having the above-described configuration, a sensor unit including the optical sensor element S is provided around the display area 21a, and the backlight is adjusted according to the intensity of received external light. Application to a configuration having a function is also possible. In this case, the circuit configuration of the sensor unit including the optical sensor element S can be configured as shown in FIG.

  That is, in the sensor element S, the n-type region (cathode) 7n is connected to the power supply line (Vdd), and the p-type region (anode) 7p is connected to the capacitor element Cs, the reset circuit, and the readout circuit. The two control electrodes G1 and G2 provided on both surfaces of each photosensor element S are connected to independent control lines 51 and 52, respectively. The other electrode of the capacitive element Cs is connected to the power supply line (Vss).

  In the photosensor element S, charges corresponding to the amount of received light are accumulated in the capacitive element Cs while being reset by a signal from the reset circuit. The charge accumulated in the capacitive element Cs is output to the outside by a signal from the readout circuit.

  Further, in such a display device, the electric light output from the optical sensor element S is used instead of the light receiving drive circuit 24, the image processing unit 25, and the application program execution unit 26 provided in the display device 20 shown in FIG. It is assumed that a circuit for controlling the light intensity of the backlight is provided based on the signal.

  Even in the display device having such a configuration, the use of the photosensor element S with improved light receiving sensitivity makes it possible to reduce the area occupied by the photosensor element S and increase the area of the display region. .

  In the above embodiment, the liquid crystal display device is exemplified as the display device having the sensor function (imaging function). However, the display device is not limited to the liquid crystal display device as long as the display device includes a backlight. The same effect can be obtained by using the optical sensor element S having the inventive configuration. In the configuration of the backlight, normal white light can be used, but a backlight assisted by invisible light (infrared light or ultraviolet light) that does not affect the display may be used. In particular, when combining infrared light, the effect of the method of the present invention is significant in combination with the improvement in sensitivity in the long wavelength region. In addition, in a self-luminous display in which an organic LED (OLED) is formed on a circuit surface without using a backlight, the same effect can be obtained by adopting the configuration provided with the photosensor element of the present invention. it can.

  Moreover, in the above embodiment, the example which comprised each layer of the optical sensor element S using the same layer as the layer which comprises the thin film transistor of a pixel part or a peripheral region was demonstrated. However, the display device of the present invention only needs to have the configuration including the photosensor element S described with reference to FIG. 1, and the effect of reducing the area occupied by the photosensor element S and increasing the area of the display region can be obtained. Is possible.

<Application example>
The display device according to the present invention described above is input to various electronic devices shown in FIGS. 9 to 13 such as digital cameras, notebook personal computers, mobile terminal devices such as mobile phones, and video cameras. The present invention can be applied to display devices for electronic devices in all fields that display a video signal or a video signal generated in the electronic device as an image or video. An example of an electronic device to which the present invention is applied will be described below.

  FIG. 9 is a perspective view showing a television to which the present invention is applied. The television according to this application example includes a video display screen unit 101 including a front panel 102, a filter glass 103, and the like, and is created by using the display device according to the present invention as the video display screen unit 101.

  10A and 10B are diagrams showing a digital camera to which the present invention is applied. FIG. 10A is a perspective view seen from the front side, and FIG. 10B is a perspective view seen from the back side. The digital camera according to this application example includes a light emitting unit 111 for flash, a display unit 112, a menu switch 113, a shutter button 114, and the like, and is manufactured by using the display device according to the present invention as the display unit 112.

  FIG. 11 is a perspective view showing a notebook personal computer to which the present invention is applied. A notebook personal computer according to this application example includes a main body 121 including a keyboard 122 that is operated when characters and the like are input, a display unit 123 that displays an image, and the like. It is produced by using.

  FIG. 12 is a perspective view showing a video camera to which the present invention is applied. The video camera according to this application example includes a main body 131, a lens 132 for shooting an object on a side facing forward, a start / stop switch 133 at the time of shooting, a display unit 134, and the like. It is manufactured by using such a display device.

  FIG. 13 is a diagram showing a portable terminal device to which the present invention is applied, for example, a cellular phone, in which (A) is a front view in an opened state, (B) is a side view thereof, and (C) is in a closed state. (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view. The mobile phone according to this application example includes an upper housing 141, a lower housing 142, a connecting portion (here, a hinge portion) 143, a display 144, a sub display 145, a picture light 146, a camera 147, and the like. And the sub display 145 is manufactured by using the display device according to the present invention.

It is a schematic sectional drawing for demonstrating the structure of the optical sensor element of embodiment. It is a schematic diagram of the band structure of the semiconductor layer in the optical sensor element of the embodiment. It is a figure which shows the example of a drive of the optical sensor element of embodiment, and the element characteristic obtained by this drive. It is a figure which shows the other example of the drive of the optical sensor element of embodiment, and the element characteristic obtained by this drive. It is a figure showing the whole structure of the display apparatus which concerns on this invention. It is a figure which shows the circuit structure in the display area of the display panel in embodiment. It is a schematic sectional drawing for demonstrating the structure of the pixel part in the display apparatus of embodiment, and the structure of a sensor part. It is a figure which shows the other example of the circuit structure of the sensor part in the display apparatus of embodiment. It is a perspective view which shows the television to which this invention is applied. It is a figure which shows the digital camera to which this invention is applied, (A) is the perspective view seen from the front side, (B) is the perspective view seen from the back side. 1 is a perspective view showing a notebook personal computer to which the present invention is applied. It is a perspective view which shows the video camera to which this invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the portable terminal device to which this invention is applied, for example, a mobile telephone, (A) is the front view in the open state, (B) is the side view, (C) is the front view in the closed state , (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate (1st board | substrate), 5 ... Gate insulating film, 7 ... Semiconductor layer, 7i ... Light-receiving part (i-type area | region), 7n ... n-type area | region, 7p ... p-type area | region, 9 ... Interlayer insulating film (gate insulation) Membrane), 13 ... Flattened insulating film, 13a ... Opening window, 20 ... Display device, 21a ... Display area, 31 ... Pixel part, 31c ... Pixel electrode, G1 ... First control electrode, G2 ... Second control electrode, S ... Optical sensor element, Tr ... Thin film transistor

Claims (14)

In an optical sensor element including a semiconductor layer in which a p-type region and an n-type region are provided in a state where an i-type region used as a light receiving unit is sandwiched,
On both side surfaces of the semiconductor layer, two control electrodes are provided electrically and independently at positions sandwiching the i-type region with a gate insulating film interposed therebetween. In the optical sensor element according to claim 1,
At least one of the two control electrodes has optical transparency. An optical sensor element, wherein: A semiconductor layer provided with a p-type region and an n-type region with an i-type region used as a light-receiving portion sandwiched therebetween is provided, and the i-type region is sandwiched between gate electrodes on both side surfaces of the semiconductor layer. A method of driving an optical sensor element provided with two control electrodes,
The method of driving an optical sensor element, wherein the two control electrodes are independently controlled when an electric signal is read from the i-type region. The method of driving an optical sensor element according to claim 3,
The method of driving an optical sensor element, wherein an electric signal amount read from the i-type region is controlled by a voltage applied to the two control electrodes. The method of driving an optical sensor element according to claim 3,
A read voltage applied between the p-type region and the n-type region when an electric signal is read from the i-type region is controlled by a voltage applied to the two control electrodes. Driving method. In a display device in which a photosensor element and a pixel portion are provided on a substrate,
The sensor element is
A semiconductor layer provided with a p-type region and an n-type region in a state of sandwiching an i-type region used as a light receiving portion;
A display device, comprising: two control electrodes that are electrically and independently provided via gate insulating films at positions sandwiching the i-type region on both side surfaces of the semiconductor layer. The display device according to claim 6, wherein
Of the two control electrodes, the control electrode provided on the upper surface side of the semiconductor layer is formed of the same layer as the pixel electrode provided in the pixel portion. The display device according to claim 7, wherein
The pixel electrode is formed on a planarization insulating film that covers an upper portion of the substrate,
The display device, wherein the control electrode formed of the same layer as the pixel electrode is disposed on the semiconductor layer in an opening window formed in the planarization insulating film. The display device according to claim 6, wherein
A thin film transistor for driving the pixel electrode is provided on the substrate.
The semiconductor layer is composed of the same layer as a semiconductor layer of a thin film transistor for driving the pixel electrode,
One of said two control electrodes is comprised by the same layer as the gate electrode of the said thin-film transistor. The display apparatus characterized by the above-mentioned. The display device according to claim 6, wherein
At least one of the two control electrodes has optical transparency. The display device according to claim 6, wherein
A plurality of the optical sensor elements are arranged in a display area in which the pixel portion is arranged. The display device according to claim 6, wherein
A display device, wherein a backlight is provided on the back side of the substrate. A semiconductor layer in which a p-type region and an n-type region are provided in a state where an i-type region used as a light-receiving portion is sandwiched is provided on a substrate provided with a pixel portion, and gate insulating films are provided on both side surfaces of the semiconductor layer. A method of driving a display device provided with an optical sensor element in which two control electrodes are arranged at positions sandwiching the i-type region,
An electric signal is read from the i-type region of the photosensor element by independently controlling two control electrodes provided on the photosensor element. The driving method of the display device according to claim 13.
A method for driving a display device, characterized in that the light intensity of a backlight provided on the back side of the substrate is controlled based on the magnitude of an electrical signal read from the i-type region.

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