JP2011039125A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which has an optical sensor element and a dark current compensation element, included in pixel, and is so constituted that the aperture ratio of the pixel is improved and the increase of production man-hour is prevented. <P>SOLUTION: The display device includes pixels having an optical sensor element and a dark current compensation element, provided on a substrate. The optical sensor element and the dark current compensation element each comprises an MIS thin film transistor of a bottom gate structure, and is so constituted as to have a pair of electrodes opposing each other on the surface of a semiconductor layer composed of a sequential laminated body of a microcrystal semiconductor and an amorphous semiconductor. At least the dark current compensation element is so formed that a gate electrode protrudes the forming region of the semiconductor layer in planar view. The pair of electrodes are so constituted as to protrude the forming region of the semiconductor layer in planar view. The spacing width between the pair of electrodes of the dark current compensation element is formed to be smaller than the spacing width between the pair of electrodes of the optical sensor element. The display device has a light shielding film shielding the incident light on the spacing portion between the pair of electrodes of the dark current compensation element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device, and more particularly, to a display device including an optical sensor element.

  For example, a liquid crystal display device (panel) displays an image by controlling the light transmittance of each pixel arranged in a matrix in the display area.

  In recent years, a liquid crystal display device has a function in which a photosensor circuit (photosensor element) is formed in each pixel and a photosensor circuit is replaced with, for example, a resistive touch panel or a capacitive touch panel. What has been known to have. That is, when a light shield such as a finger is brought into contact with (or brought close to) the display area of the liquid crystal display device, the light sensor element senses this, and the photosensor circuit calculates the x and y coordinates of the light shield. The calculation result is reflected in the information displayed on the image.

  In this case, the optical sensor element is usually configured as a diode connection structure of a MIS (Metal Insulator Semiconductor) type thin film transistor. This is because, in each pixel of the liquid crystal display device, a thin film transistor called a so-called switching element for pixel selection is formed. Therefore, it is convenient to manufacture an optical sensor element in parallel with this thin film transistor. Because it is good.

  In addition, as a document relevant to this invention, there exists the following patent document 1, for example. Japanese Patent Application Laid-Open No. H10-228667 includes a photosensor circuit including a photosensor element having a diode connection structure of a thin film transistor in a liquid crystal display device, and a dark current compensation element that has the same structure as the photosensor element and that is prevented from being irradiated with light by a light shielding film. Thus, there is disclosed a technique for correcting a dark current generated in an optical sensor element and achieving highly accurate optical detection.

JP 2007-179000 A

  In recent years, the present applicant has attempted to use a bottom-gate MIS type structure as the optical sensor element, in which a semiconductor layer is formed by using a sequential stack of a microcrystalline semiconductor layer and an amorphous semiconductor layer. ing.

  Such an optical sensor element can constitute a mechanism in which generation of electron-hole pairs by incidence of light is performed in an amorphous semiconductor layer, and separation of electrons and holes is performed in a microcrystalline semiconductor layer. In the amorphous semiconductor layer, sufficient generation of electron-hole pairs is made even by light having a long wavelength, and in the microcrystalline semiconductor layer, sufficient separation of generated electron-holes is made, This is because an excellent photoelectric conversion efficiency can be obtained.

  However, even in such an optical sensor element, a dark current due to thermal excitation is unavoidable, and countermeasures have been desired. In this case, the technique described in Patent Document 1 is applied, a dark current compensation element is formed adjacent to the photosensor element, and high-precision photodetection is achieved by correcting the dark current generated in the photosensor element. It is possible.

  However, in the dark current compensation element disclosed in Patent Document 1, a light shielding film that shields light incident through the substrate is formed on one substrate side on which the dark current compensation element is formed, and a liquid crystal is used. A light-shielding film that shields light incident through the substrate is also formed on the other substrate side that is disposed.

  For this reason, each of the light shielding films must be formed by sufficiently covering the dark current compensation element, so that it must be formed with a relatively large area, which causes a decrease in the aperture ratio of the pixel. Further, since the light shielding film is formed on each of the substrates sandwiching the liquid crystal, the number of manufacturing steps is increased.

  An object of the present invention is to provide a display device that includes a photosensor element and a dark current compensation element in a pixel, improves the aperture ratio of the pixel, and avoids an increase in the number of manufacturing steps. It is in.

  The configuration of the present invention can be as follows, for example.

(1) A display device of the present invention includes a pixel including a photosensor element and a dark current compensation element on a substrate, and each of the photosensor element and the dark current compensation element is a MIS thin film transistor having a bottom gate structure. And comprising a pair of electrodes facing each other on the upper surface of a semiconductor layer composed of a sequentially laminated body of a microcrystalline semiconductor and an amorphous semiconductor, and at least the dark current compensation element includes a planar electrode. The pair of electrodes are formed so as to protrude from the formation region of the semiconductor layer when viewed in plan, and the pair of dark current compensating elements is formed. The electrode separation width is formed to be smaller than the pair of electrode separation widths of the photosensor element, and blocks light incident on the pair of electrode separation portions of the dark current compensation element. Characterized in that it comprises an optical film.

(2) The display device according to the present invention includes, in (1), a power supply line that supplies a predetermined voltage, a ground line that supplies a ground voltage, and a capacitive element. And the second electrode of the photosensor element is connected to the gate electrode of the photosensor element, and the second electrode of the dark current compensation element and the dark current compensation are connected to each other. A gate electrode of the device is connected, the first electrode of the photosensor device is connected to the second electrode of the dark current compensation device, and the second electrode of the photosensor device is connected to the ground The first electrode of the dark current compensation element is connected to the power supply line, the capacitive element has a pair of terminals, and one terminal has the first electrode of the photosensor element. Connected to a connection point between the electrode and the second electrode of the dark current compensation element; The ground voltage is supplied to the other terminal different from the one terminal, and the voltage at the connection point between the first electrode of the photosensor element and the second electrode of the dark current compensation element is set as the light. It is extracted as an output of the sensor element.

(3) In the display device of the present invention according to (1) or (2), the light shielding film is formed on at least the pair of electrodes of the dark current compensation element on the upper surface of the insulating film covering the dark current compensation element. It is characterized in that it is formed so as to be overlapped with the separated portion.

(4) The display device of the present invention is the display device according to (1) or (2), wherein the display device is a liquid crystal display device, wherein the substrate is the first substrate and the substrate is disposed opposite to the substrate with the liquid crystal interposed therebetween. When the second substrate is used, the light shielding film is formed on the liquid crystal side surface of the second substrate.

(5) In the display device of the present invention, in (1) to (4), the photosensor element is formed so that the gate electrode protrudes from the formation region of the semiconductor layer when viewed in plan. It is characterized by.

(6) In the display device of the present invention, in (1) to (5), the pair of electrodes of the photosensor element is formed so as to protrude from the formation region of the semiconductor layer in plan view. It is characterized by that.

(7) The display device according to the present invention includes, in (1) to (6), a plurality of pixels arranged in a matrix that constitutes a display area, and includes the photosensor element and the dark current compensation element. Further, the pixels are scattered in the display area.

(8) The display device of the present invention is characterized in that, in (7), the photosensor element and the dark current compensation element are formed in all of the plurality of pixels.

(9) In the display device of the present invention, in (7), the photosensor element and the dark current compensation element are formed in one of a plurality of pixels grouped adjacent to each other in the display region. It is characterized by being.

(10) The display device according to the present invention includes, in (1) to (6), a plurality of pixels arranged in a matrix that forms a display region, and includes the photosensor element and the dark current compensation element. The pixels are scattered in a part of the display area.

(11) The display device of the present invention is characterized in that, in (10), the photosensor element and the dark current compensation element are formed in all of the pixels in the partial region.

(12) In the display device of the invention, in (10), the photosensor element and the dark current compensation element are one of a plurality of pixels grouped adjacent to each other in the partial region. It is characterized by being formed.

(13) The display device of the present invention is a liquid crystal display device.

(14) The display device of the present invention is an organic FL display device.

(15) In the display device of the present invention, in (1) to (14), the microcrystalline semiconductor is microcrystalline silicon, and the amorphous semiconductor is amorphous silicon.

  The above-described configuration is merely an example, and the present invention can be modified as appropriate without departing from the technical idea. Further, examples of the configuration of the present invention other than the above-described configuration will be clarified from the entire description of the present specification or the drawings.

  According to the display device having such a configuration, the pixel is provided with the photosensor element and the dark current compensation element, and the aperture ratio of the pixel is improved to avoid an increase in the number of manufacturing steps. Can do.

  Other effects of the present invention will become apparent from the description of the entire specification.

It is sectional drawing which showed the optical sensor element and dark current compensation element of Example 1 of the display apparatus of this invention. It is the top view which showed the outline of Example 1 of the display apparatus of this invention. It is an equivalent circuit diagram which shows the sensor part of the photo sensor circuit of Example 1 of the display apparatus of this invention. It is an equivalent circuit diagram which shows the signal processing part of the said photo sensor circuit. It is a graph which shows the photoelectric conversion efficiency of the optical sensor element of the display apparatus of this invention. It is a graph which shows the dark current which generate | occur | produces in the optical sensor element of the display apparatus of this invention. It is sectional drawing which showed the optical sensor element and dark current compensation element of Example 2 of the display apparatus of this invention. It is explanatory drawing which shows Example 4 of the display apparatus of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In each drawing and each example, the same or similar components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 2 is a schematic plan view of Embodiment 1 of the display device of the present invention. FIG. 2 shows a liquid crystal display device (panel).

  In FIG. 2, there is a pair of substrates SUB1 and SUB2 that are arranged to face each other with a liquid crystal (not shown) interposed therebetween. The substrate SUB2 (hereinafter referred to as the second substrate SUB2) has a smaller area than the substrate SUB1 (hereinafter referred to as the first substrate SUB1), and exposes the lower side of the first substrate SUB1 in the drawing. It has become. This is because the semiconductor device (chip) SEC is mounted on the side portion of the first substrate SUB1. The semiconductor chip SEC drives each pixel in the display area AR described later.

  A sealing material (not shown) is formed between the second substrate SUB2 and the first substrate SUB1, and a region surrounded by the sealing material (a region surrounded by a dotted line in the drawing) constitutes a display region AR. It is supposed to do.

  In the display area AR, on the liquid crystal side surface of the first substrate SUB1, gate signal lines GL extending in the x direction in the drawing and juxtaposed in the y direction, and extending in the y direction in the drawing and x Drain signal lines DL arranged in parallel in the direction are formed. A region surrounded by a pair of adjacent gate signal lines GL and a pair of adjacent drain signal lines DL constitutes a pixel region. As a result, the display area AR has a large number of pixels arranged in a matrix.

  In each pixel region, as shown in the enlarged view of the solid circle A, the thin film transistor TFT that is turned on by a signal (scanning signal) from the gate signal line GL and the drain signal line DL through the turned on thin film transistor TFT. A pixel electrode PX to which a signal (video signal) is supplied, and a counter electrode CT that generates an electric field between the pixel electrode PX are formed. The counter electrode CT is supplied with a reference signal (reference signal) for the video signal through the common signal line CL. Each pixel configured as described above can control the transmittance of light passing therethrough by driving the liquid crystal of the pixel by an electric field generated between the pixel electrode PX and the counter electrode CT. The above-described configuration of the pixel is a so-called IPS (In Plane Switching) system, but is not limited to this, for example, a TN (Twisted Nematic) system or a VA (Vertical Alignment) system. May be.

Although not shown in FIG. 2, the display device according to the present invention includes, for example, a photosensor element LSE, a dark current compensation element DCE, and a capacitor element CPE among elements constituting the photosensor circuit. Is formed. In this case, in each pixel of the display device, the region is geometrically divided into two, one region is used as the display region, the thin film transistor TFT, the pixel electrode PX, and the counter electrode CT are arranged, and the other region is the light detection region. As an alternative, the optical sensor element LSE, the dark current compensation element DCE, and the capacitive element CPE may be arranged.

  FIG. 3 is a diagram showing an equivalent circuit of the photosensor element LSE, dark current compensation element DCE, and capacitive element CPE formed in the pixel region. The optical sensor element LSE, dark current compensation element DCE, and capacitive element CPE are configured as a sensor part of a photosensor circuit. In FIG. 3, a dark current compensation element DCE and an optical sensor element LSE are connected in series between a power supply line VDD and a ground line GND for supplying a ground voltage. Between the intermediate connection portion of this series connection body and the ground line GND. Is connected to a capacitive element CPE. The output of the photo sensor circuit is extracted as a signal Vin from an intermediate connection portion between the dark current compensation element DCE and the photo sensor element LSE. In FIG. 3, the dark current Idk flows through the dark current compensation element DCE, and the sum of the dark current Idk and the photocurrent Iph flows through the photosensor element LSE.

  FIG. 4 shows a current-voltage conversion circuit to which a signal Vin that is an output of the circuit shown in FIG. 3 is inputted. This voltage conversion circuit is configured as an operational amplifier, and is configured as a signal processing unit of the photosensor circuit. In order to stabilize the operation, this current-voltage conversion circuit is formed, for example, as a semiconductor device (chip) mounted outside the display area AR of the liquid crystal display device. This semiconductor device is the semiconductor device SEC shown in FIG. There may be. Further, in the case where the drive circuit is constituted by thin film transistors formed of polycrystalline silicon around the display area AR of the first substrate SUB1, the voltage conversion circuit may be provided in the drive circuit.

  FIG. 1 is a configuration diagram showing an optical sensor element LSE and a dark current compensation element DCE formed in a pixel region of a liquid crystal display device (panel). In FIG. 1, the upper drawing shows a cross-sectional view, and the lower drawing shows a plan view. As described above, the thin film transistor TFT, the pixel electrode PX, and the like are formed in the pixel region, and a signal line, an interlayer insulating film, and the like are also formed in accordance with the formation. However, FIG. These drawings are omitted.

  Of the first substrate SUB1 and the second substrate SUB2 that are opposed to each other with the liquid crystal LC interposed therebetween, the photosensor element LSE and the dark current compensation element DCE are formed on the surface (front surface) of the first substrate SUB1 on the liquid crystal LC side. ing. Here, although not shown, it is assumed that a backlight is disposed on the surface of the first substrate SUB1 opposite to the liquid crystal LC.

The optical sensor element LSE is formed as follows. First, the gate electrode GT1 is formed on the surface of the first substrate SUB1. The gate electrode GT1 is formed to have a relatively large width in order to block the light from the backlight incident through the first substrate SUB1 from entering the optical sensor element LSE. A gate insulating film GI is formed on the first substrate SUB1 so as to cover the gate electrode GT.

  In a region overlapping with the gate electrode GT on the upper surface of the gate insulating film GI, a microcrystalline semiconductor layer μPS1 made of, for example, microcrystalline silicon (average grain size of 100 nm or less) and an amorphous semiconductor layer AS1 made of, for example, amorphous silicon are sequentially formed. A semiconductor layer SCL1 made of a stacked body is formed. In this case, the semiconductor layer SCL1 is formed in a substantially central region of the gate electrode GT1, and the gate electrode GT1 is formed so as to protrude from the semiconductor layer SCL1 in plan view. Thus, the gate electrode GT1 can almost completely shield the light from the backlight incident through the first substrate SUB1 from entering the semiconductor layer SCL1. The optical sensor element LSE in this embodiment is used as a sensor unit of a photo sensor circuit having a function as a touch panel, for example, and only needs to be able to detect light incident through the second substrate SUB2. In this detection, the light from the backlight is This is inconvenient. In this case, since the gate electrode GT1 is configured to also block the light incident through the first substrate SUB1, the effect of avoiding an increase in the number of manufacturing steps can be avoided as compared with the case where a light blocking film is separately formed. Play.

  On the upper surface of the semiconductor layer SCL1, a drain electrode DT1 and a source electrode ST1 are formed so as to face each other. The drain electrode DT1 is configured to protrude from the formation region of the semiconductor layer SCL1 when viewed in a plane, and the source electrode ST1 is also configured to protrude from the formation region of the semiconductor layer SCL1 when viewed from a plane. Yes. Here, the drain electrode DT1 and the source electrode ST1 are separated by a distance W1, and the surface of the semiconductor layer SCL1 exposed from between the drain electrode DT1 and the source electrode ST1 receives the light L incident through the second substrate SUB2. It is configured as a detection surface for detection. Therefore, in the optical sensor element LSE, a detection surface having a large area can be formed by increasing the distance W1 between the drain electrode DT1 and the source electrode ST1.

  Although not shown, an amorphous semiconductor layer doped with a high concentration impurity is formed on the surface of the semiconductor layer SCL1 and at the interface between the drain electrode DT1 and the source electrode ST1. It functions as a contact layer. In addition, in a MIS (Metal Insulator Semiconductor) type transistor, the drain electrode DT1 and the source electrode ST1 are usually interchanged depending on the bias application state. The electrode is designated as a drain electrode DT1, and the right electrode in the figure is designated as a source electrode ST1.

  The optical sensor element LSE configured in this manner generates a photocurrent when irradiated with light, as shown by a curve α in FIG. The horizontal axis of the graph shown in FIG. 5 indicates the luminance (cd / m 2) from the backlight, and the vertical axis indicates the photocurrent (pA). The photocurrent shown in FIG. 5 is a value in a state where an off voltage is applied to the gate electrode of the photosensor element LSE. In FIG. 5, for comparison, the semiconductor layer is composed of only amorphous silicon, and in other configurations, the amount of photocurrent generated in an element having the same configuration as the photosensor element LSE is indicated by a curve β. According to FIG. 5, it is found that the photosensor element LSE having the above-described configuration generates a very large amount of photocurrent. This is because the photoelectrons and holes generated in the amorphous semiconductor layer AS1 are efficiently separated in the microcrystalline semiconductor layer μPS1 stacked with the amorphous semiconductor layer AS1 by the incident light. it is conceivable that.

  The dark current compensation element DCE is formed as follows. A gate electrode GT2 is formed on the surface of the first substrate SUB1. This gate electrode GT2 is formed simultaneously with the formation of the gate electrode GT1 of the photosensor element LSE. The gate electrode GT2 is formed to have a relatively large width in order to shield the light from the backlight incident through the first substrate SUB1 from entering the dark current compensation element DCE.

  A gate insulating film GI is formed on the first substrate SUB1 so as to cover the gate electrode GT2. Further, a semiconductor formed by sequentially stacking a microcrystalline semiconductor layer μPS2 made of, for example, microcrystalline silicon and an amorphous semiconductor layer AS2 made of, for example, amorphous silicon, in a region overlapping with the gate electrode GT2 on the upper surface of the gate insulating film GI. A layer SCL2 is formed. In this case, the semiconductor layer SCL2 is formed in a substantially central region of the gate electrode GT2, and the gate electrode GT2 is formed so as to protrude from the semiconductor layer SCL2 in plan view. As a result, the gate electrode GT2 can almost completely shield the light from the backlight incident through the first substrate SUB1 from entering the semiconductor layer SCL2. In this case, since the gate electrode GT2 is configured to also block light incident through the first substrate SUB1, an effect of avoiding an increase in the number of manufacturing steps can be avoided as compared with the case where a light blocking film is separately formed. Play. The semiconductor layer SCL2 is formed simultaneously with the formation of the semiconductor layer SCL2 of the photosensor element LSE.

  On the upper surface of the semiconductor layer SCL2, a drain electrode DT2 and a source electrode ST2 are formed so as to face each other. The drain electrode DT2 and the source electrode ST2 are formed simultaneously with the formation of the drain electrode DT1 and the source electrode ST1 of the photosensor element LSE. The drain electrode DT2 is configured to protrude from the formation region of the semiconductor layer SCL2 in a plan view, and the source electrode ST2 is also configured to protrude from the formation region of the semiconductor layer SCL2 in a plan view. Yes. Here, the drain electrode DT2 and the source electrode ST2 are separated by a distance W2 (<W1), and the distance W2 is formed to be small enough to achieve electrical insulation between the drain electrode DT2 and the source electrode ST2. This is because the dark current compensation element DCE is configured so that the light incident through the second substrate SUB2 is not irradiated to the semiconductor layer SCL2 as much as possible. Thereby, when the dark current compensation element DCE is shielded against light incident through the second substrate SUB2 by the light shielding film SHL described later, the area of the light shielding film SHL can be made small.

  Although not shown in the drawing, as in the case of the optical sensor element LSE, the surface of the semiconductor layer SCL2 and the interface between the drain electrode DT2 and the source electrode ST2 are amorphous doped with high-concentration impurities. A semiconductor layer is formed, and this layer functions as a contact layer.

  On the surface of the second substrate SUB2 that faces the dark current compensation element DCE, a light shielding film SHL that prevents light from being applied to the semiconductor layer SCL2 of the dark current compensation element DCE through the second substrate SUB2 is formed. The light shielding film SHL is formed simultaneously with the black matrix for covering the thin film transistor TFT or the like. The light shielding film SHL is large enough to prevent the light from being applied to the semiconductor layer SCL2 exposed from between the drain electrode DT2 and the source electrode ST2 of the dark current compensation element DCE. In this case, the distance W2 between the drain electrode DT2 and the source electrode ST2 of the dark current compensation element DCE is configured to be smaller than the distance W1 between the drain electrode DT1 and the source electrode ST1 of the photosensor element LSE, and the light shielding film SHL The area can be made small. This eliminates the need to form the light shielding film SHL that must be formed over the pixel region more than necessary, and has the effect of improving the aperture ratio of the pixel.

  FIG. 6 is a graph showing that the dark current Idk is generated in the dark current compensation element DCE shown in FIG. The horizontal axis of the graph shown in FIG. 6 indicates the gate voltage VG applied to the gate electrode GT2 of the dark current compensation element DCE, and the vertical axis indicates the current Id flowing through the dark current compensation element DCE. In FIG. 6, it can be seen that a predetermined current (dark current) flows even when a reverse bias voltage (for example, −5 V) is applied to the gate electrode GT2, for example. Further, since the backlight light is shielded by the gate electrode GT2, the generated current (dark current) is substantially constant even when the luminance of the backlight light is changed. Therefore, the dark current can be compensated by connecting the dark current compensating element DCE to the photosensor element LSE as shown in FIG. Therefore, a photosensor circuit that is not affected by dark current can be configured.

  As is apparent from the above description, according to the first embodiment, the dark current compensation element DCE has a configuration in which the gate electrode GT2 also serves to block light incident through the first substrate SUB1. Therefore, compared to the case where the light shielding film is separately formed, an effect of avoiding an increase in the number of manufacturing steps can be achieved. Further, the distance W2 between the drain electrode DT2 and the source electrode ST2 of the dark current compensation element DCE is configured to be small (smaller than the distance W1 between the drain electrode DT1 and the source electrode ST1 of the photosensor element LSE). Therefore, it is not necessary to form the light shielding film SHL that has to be formed over the pixel region more than necessary, and the aperture ratio of the pixel is improved. Furthermore, the dark current compensation element DCE is a so-called bottom gate type like the optical sensor element LSE, so that the above-described configuration can be easily achieved, and the dark current compensation element DCE is manufactured in parallel with the manufacture of the optical sensor element LSE. Will be able to. Even in this case, in the optical sensor element LSE, the gate electrode GT1 can be configured to also block the light incident through the first substrate SUB1, and compared with the case where a light shielding film is separately formed. There is an effect that an increase in man-hours can be avoided.

  In the first embodiment, a liquid crystal display device is taken as an example of the display device, and as shown in FIG. 1, a light shielding film SHL for shielding the dark current compensation element DCE is formed on the second substrate SUB2 side. It is. However, the present invention is not limited to this, and it may be formed on the first substrate SUB1 side.

  FIG. 7 is a configuration diagram showing an embodiment in which a light shielding film is formed on the first substrate SUB1 side, and is a diagram drawn in association with FIG. In FIG. 7, an insulating film IN is formed on the surface of the first substrate SUB1 so as to cover the photosensor element LSE and the dark current compensation element DCE, and a light shielding film SHL is formed on the upper surface of the insulating film IN. The film SHL is formed so as to overlap at least the gap between the drain electrode DT2 and the source electrode ST2 of the dark current compensation element DCE. Note that the insulating film IN may be a stacked body of a plurality of insulating films made of different materials. Further, a signal line or the like may be interposed between the stacked bodies, and the function of the light shielding film SHL may be provided by an extension portion of the signal line or the like. When configured in this manner, the light shielding film SHL can be formed close to the dark current compensation element DCE (close to the vertical direction of the first substrate SUB1), and thus has an effect of being able to be formed with a smaller area.

  In the first embodiment, the optical sensor element LSE and the dark current compensation element DCE are incorporated in the area of each pixel in the display area AR. However, a configuration may be adopted in which the photosensor element LSE and the dark current compensation element DCE are incorporated into one of a plurality of pixels grouped adjacent to each other. That is, in the display area AR, the optical sensor elements LSE and the dark current compensation elements DCE are scattered and arranged in a rough state. This is because when the photo sensor circuit having the photo sensor element LSE has a touch panel function, even if the pitch of the photo sensor elements LSE adjacent to each other is increased and scattered in the display area AR, a sufficient function is exhibited. Because it can.

  In the first and second embodiments, the optical sensor elements LSE are arranged so as to be evenly distributed over the entire display area AR. However, the optical sensor elements LSE may be scattered and arranged in a part of the display area AR.

  FIG. 8 is a diagram showing a region in which the optical sensor elements LSE are scattered and is illustrated in association with FIG. In FIG. 8, among the display area AR of the liquid crystal display device, for example, the optical sensor elements LSE are scattered and arranged in the area on the lower side in the figure (indicated by a one-dot chain line B in the figure). is there. In this case, the photosensor element LSE and the dark current compensation element DCE may be incorporated in each pixel within the one-dot chain line frame B in the drawing. Further, in the one-dot chain line frame B in the figure, the photosensor element LSE and the dark current compensation element DCE may be incorporated into one of a plurality of pixels grouped adjacent to each other.

  The reason for this configuration is that, in the display area AR, for example, a plurality of so-called soft switches arranged side by side are often displayed in the area indicated by a one-dot chain line B in the figure. This is because the touch panel function may be provided in the area indicated by the alternate long and short dash line B in the figure.

  Note that it is needless to say that a part of the display area AR to which the present invention is applied is not limited to the part shown in FIG. 8, and may be another part.

  In the above-described embodiments, the liquid crystal display device has been described as an example. However, the present invention is not limited to this, and can be applied to other display devices such as an organic EL display device.

  An organic EL display device is greatly different from a liquid crystal display device in that a self-luminous light emitting element is used as a display pixel. Thereby, the organic EL display device has a configuration without a backlight. Therefore, in the optical sensor element LSE and the dark current compensation element DCE shown in FIG. 1, the gate electrodes GT1 and GT2 do not need to be formed so as to protrude from the semiconductor layers SCL1 and SCL2 in a plan view. The layers SCL1 and SCL2 may be configured to protrude from the gate electrodes GT1 and GT2. This is because there is no backlight, so that the influence does not reach the optical sensor element LSE and the semiconductor layers SCL1 and SCL2 of the dark current compensation element DCE.

  The present invention has been described using the embodiments. However, the configurations described in the embodiments so far are only examples, and the present invention can be appropriately changed without departing from the technical idea. Further, the configurations described in the respective embodiments may be used in combination as long as they do not contradict each other.

  SUB1 ... first substrate, SUB2 ... second substrate, AR ... display region, SEC ... semiconductor device (chip), GL ... gate signal line, DL ... drain signal line, TFT ... thin film transistor, PX ... ... Pixel electrode, CT ... Counter electrode, CL ... Common signal line, LSE ... Photo sensor element, GT1 ... Gate electrode, GI ... Gate insulating film, μPS1 ... Microcrystalline semiconductor layer, AS1 ... Amorphous Semiconductor layer, SCL1 ... semiconductor layer, DT1 ... drain electrode, ST1 ... source electrode, DCE ... dark current compensation element, GT2 ... gate electrode, GI ... gate insulating film, μPS2 ... microcrystalline semiconductor layer AS2... Amorphous semiconductor layer, SCL2... Semiconductor layer, DT2... Drain electrode, ST2... Source electrode, CPE... Capacitive element, SHL.

Claims (15)

A pixel having a photosensor element and a dark current compensation element on a substrate;
Each of the optical sensor element and the dark current compensation element is composed of a MIS thin film transistor having a bottom gate structure, and a pair of electrodes facing each other on an upper surface of a semiconductor layer composed of a sequentially stacked body of a microcrystalline semiconductor and an amorphous semiconductor. Configured with
At least the dark current compensation element is formed such that the gate electrode protrudes from the formation region of the semiconductor layer when viewed in plan, and the pair of electrodes is formed as the region of formation of the semiconductor layer when viewed in plan. Configured to protrude
The separation width of the pair of electrodes of the dark current compensation element is formed smaller than the separation width of the pair of electrodes of the photosensor element,
A display device comprising: a light-shielding film that shields light incident on a separation portion of the pair of electrodes of the dark current compensation element. A power supply line for supplying a predetermined voltage, a ground line for supplying a ground voltage, and a capacitive element;
The pair of electrodes includes a first electrode and a second electrode,
The second electrode of the photosensor element and the gate electrode of the photosensor element are connected;
The second electrode of the dark current compensation element and the gate electrode of the dark current compensation element are connected;
The first electrode of the photosensor element is connected to the second electrode of the dark current compensation element;
The second electrode of the photosensor element is connected to the ground line;
The first electrode of the dark current compensation element is connected to the power supply line;
The capacitive element has a pair of terminals, and one terminal is connected to a connection point between the first electrode of the photosensor element and the second electrode of the dark current compensation element, and the one terminal Is supplied with the ground voltage to the other different terminal,
The display device according to claim 1, wherein a voltage at the connection point between the first electrode of the photosensor element and the second electrode of the dark current compensation element is taken out as an output of the photosensor element. .   2. The light shielding film is formed on an upper surface of an insulating film covering the dark current compensation element so as to overlap at least a separation portion of the pair of electrodes of the dark current compensation element. Or the display apparatus of Claim 2. The display device is a liquid crystal display device, and when the substrate is a first substrate and the substrate disposed opposite to the substrate with the liquid crystal sandwiched is a second substrate,
The display device according to claim 1, wherein the light shielding film is formed on a surface of the second substrate on the liquid crystal side.   5. The display according to claim 1, wherein the gate electrode of the photosensor element is formed so as to protrude from a region where the semiconductor layer is formed in a plan view. apparatus.   6. The pair of electrodes of the optical sensor element is formed so as to protrude from a region where the semiconductor layer is formed in a plan view. Display device. It has a plurality of pixels arranged in a matrix that constitutes the display area,
The display device according to claim 1, wherein the pixels provided with the photosensor elements and the dark current compensation elements are scattered in the display area.   The display device according to claim 7, wherein the photosensor element and the dark current compensation element are formed in all of the plurality of pixels.   The display according to claim 7, wherein the photosensor element and the dark current compensation element are formed in one of a plurality of pixels grouped adjacent to each other in the display region. apparatus. It has a plurality of pixels arranged in a matrix that constitutes the display area,
The said pixel provided with the said optical sensor element and the said dark current compensation element is scattered in the one part area | region of the said display area, The any one of Claims 1-6 characterized by the above-mentioned. The display device described.   The display device according to claim 10, wherein the photosensor element and the dark current compensation element are formed in all of the pixels in the partial region.   11. The photo sensor element and the dark current compensation element are formed in one of a plurality of pixels grouped adjacent to each other in the partial region. Display device.   The display device according to claim 1, wherein the display device is a liquid crystal display device.   The display device according to any one of claims 1, 2, 3, 5 to 12, wherein the display device is an organic FL display device.   The display device according to claim 1, wherein the microcrystalline semiconductor is microcrystalline silicon, and the amorphous semiconductor is amorphous silicon.

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