JP2009237286A - Liquid crystal display element and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element, capable of taking in an image with a high SN ratio in an output signal, by improving the light reception efficiency in a light-receiving element, and to provide a liquid crystal display that uses the liquid crystal display element. <P>SOLUTION: The liquid crystal display element includes a liquid crystal layer 4, held in between a front substrate 2 and a rear substrate 3 and is provided with a light-receiving element 7 formed on a ground layer 41, provided on the rear substrate 3 and a pixel electrode 27 formed on an insulating layer 6 provided on the light receiving element 7. When the liquid crystal element is plane-viewed from the front substrate 2 side, a reflection film 34 for reflecting an external light 13 which is made incident, while transmitting the front substrate 2 toward a light receiving region 52 is formed at least on a part of the periphery of the light-receiving region 52 of the light-receiving element 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element having a light receiving element in a pixel and a liquid crystal display device including the liquid crystal display element, and more particularly to a liquid crystal display element and a liquid crystal display device in which the light receiving efficiency of the light receiving element is improved.

  Conventionally, a display device using a liquid crystal display element with a sensor function that can capture an image of an object close to a display by providing a light receiving element such as a photodiode in a pixel has been proposed. Such a display device using a liquid crystal display element having a sensor function capable of capturing an image is assumed to be used as a display device having a touch panel function or a display device having a scanner function.

  In a conventional liquid crystal display element with a sensor function, a well-known component such as a wiring electrode such as a gate wiring or a source wiring, a TFT (Thin Film Transistor) as a switching element, or a pixel electrode is used as a semiconductor in an active matrix substrate which is a back substrate. When forming by a process, a photodiode as a light receiving element, and a drive circuit element and a wiring electrode for detecting the signal are simultaneously formed in a pixel (see Patent Document 1).

In addition, a so-called transflective liquid crystal element in which part of the pixel electrode is a reflective electrode formed of a metal film that reflects external light, such as an aluminum film, and both transmitted light from the backlight and external light are used for image display. In Japanese Patent Application Laid-Open No. H11-260, a photodiode is formed under the reflective electrode, and an opening is formed in the reflective electrode at a position overlapping the light receiving region of the photodiode (see Patent Document 2).
JP 2006-79589 A JP 2006-330578 A

  In the conventional liquid crystal display element with a sensor function described above, image display as a liquid crystal display element cannot be performed in a portion where the light receiving element is formed. In addition, there is a basic request for an image display element to increase the ratio of an image displayable area in one pixel as much as possible, and in order to be limited by this requirement, the area of the light receiving area of the light receiving element is not much. You can't make it bigger. Furthermore, in liquid crystal display elements, thinning of semiconductor layers such as TFTs for image display has progressed, but as the semiconductor layers become thinner, light receiving elements formed simultaneously with the semiconductor layers for image display As a result, the photoelectric conversion rate in the light receiving element is lowered. From these backgrounds, it is clear that improving the light receiving sensitivity of the light receiving element will become an increasingly important issue in the future.

  Accordingly, in view of the above problems, the present invention provides a liquid crystal display element having a light receiving element capable of improving the light receiving efficiency of the light receiving element and obtaining an output signal having a high S / N ratio, and a liquid crystal display using the same. An object is to provide an apparatus.

  In order to solve the above problems, a liquid crystal display element of the present invention has a liquid crystal layer sandwiched between a front substrate and a rear substrate, and a light receiving element provided on a base layer provided on the rear substrate. And a pixel electrode provided on an insulating layer provided on the light receiving element, and when viewed in plan from the front substrate side, at least part of the periphery of the light receiving region of the light receiving element, A reflective film is formed that reflects external light incident through the front substrate toward the light receiving region.

  The liquid crystal display device according to the present invention outputs the light reception signal by driving the light receiving element, the liquid crystal display element according to the present invention, an image display control circuit unit for displaying an image on the liquid crystal display element. And a detection control circuit unit.

  According to the present invention, external light incident through the front substrate can be efficiently received by the light receiving element, and a liquid crystal display element having an improved S / N ratio of an output signal from the light receiving element can be obtained. it can.

  In addition, by using the liquid crystal display element according to the present invention for the display unit, a liquid crystal display device with a sensor function capable of obtaining an output signal with a high S / N ratio can be realized.

  A liquid crystal display element according to the present invention has a liquid crystal layer sandwiched between a front substrate and a back substrate, and a light receiving element provided on a base layer provided on the back substrate, and provided on the light receiving element. And a pixel electrode provided on the insulating layer. When viewed in plan from the front substrate side, the light passes through the front substrate and enters at least part of the periphery of the light receiving region of the light receiving element. A reflective film that reflects external light toward the light receiving region is formed.

  According to the above configuration, the reflection light formed on at least a part of the periphery of the light receiving region of the light receiving element can reflect the external light that has entered through the front substrate and can enter the light receiving region. . For this reason, outside light that is incident on the vicinity of the light receiving element but cannot be detected by the light receiving element can be effectively received in the light receiving region, the substantial sensitivity of the light receiving element is improved, and the output signal from the light receiving element is improved. The S / N ratio can be improved.

  In the liquid crystal display element having the above configuration, the reflection film is formed between the light receiving element and an electrode connected to the light receiving element, and an opening formed in an interlayer insulating film constituting the insulating layer. In addition, it is preferably formed on an inclined surface which is a side wall. By doing so, a reflective film that reflects external light can be easily formed at a position close to the light receiving region of the light receiving element, so that the external light reflected by the reflective film reliably enters the light receiving region. As a result, the light receiving efficiency of the light receiving element can be effectively improved.

  In this case, it is preferable that the reflective film is a metal film made of the same material as an electrode connected to the light receiving element formed on the interlayer insulating film. By doing so, the reflective film can be formed simultaneously with the source electrode and the like formed on the interlayer insulating film, and it is not necessary to provide a special process for manufacturing the reflective film.

  In addition, the reflective film is a side wall of an opening formed in the planarizing film that constitutes the insulating layer formed between the light receiving element and the electrode connected to the light receiving element and the pixel electrode. It is preferably formed on a certain inclined surface. In this way, a reflective film can be formed over the thickness direction of a planarizing film that is generally formed as a relatively thick insulating layer, so that the amount of external light that can be reflected by the reflective film increases in the area of the reflective film Will increase. As a result, the light receiving sensitivity of the light receiving element can be effectively increased.

  In this case, it is preferable that at least a part of the pixel electrode is a reflective electrode that reflects external light, and the reflective film is a metal film made of the same material as the reflective electrode. By doing so, the reflective film can be formed simultaneously with the formation of the reflective electrode, so that it is not necessary to provide a special process for manufacturing the reflective film.

  Furthermore, when viewed in plan from the front substrate side, a recess is formed at a position overlapping the light receiving region of the back substrate, and the reflective film is formed on an inclined surface that is a side wall of the recess. preferable. In this way, external light that has entered the back side of the light receiving element can also be reflected by the reflective film and received by the light receiving element, and the light receiving sensitivity of the light receiving element can be improved.

  Further, it is preferable that a light shielding film is provided between the back substrate and the base layer at a position overlapping with the light receiving element when viewed from the front substrate side. In this way, when an image is displayed using light incident from the back surface of the liquid crystal display element using a backlight or the like, the light receiving element receives irradiation light from the backlight incident from the back surface. Thus, it can be prevented that the received light signal becomes noise.

  In this case, it is preferable that the light shielding film also serves as the reflection film. In this way, it is not necessary to provide a separate step for forming the reflective film.

  Furthermore, the liquid crystal display element according to the present invention, an image display control circuit unit for displaying an image on the liquid crystal display element, and a detection control circuit unit for driving the light receiving element and outputting a light reception signal are provided. Thus, a liquid crystal display device in which the S / N ratio of the light reception signal at the light receiving element is increased can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following description of the embodiments of the present invention, a configuration example in the case where the liquid crystal display element according to the present invention is implemented as a transflective liquid crystal panel having both a reflective electrode and a transparent electrode as pixel electrodes is shown. However, the liquid crystal display element according to the present invention is not limited to a transflective liquid crystal display element, and a transmissive liquid crystal display element having no reflective electrode as a pixel electrode, or a reflective liquid crystal in which all pixel electrodes are reflective electrodes. It can also be applied to a display element.

  In addition, an example in which the liquid crystal display element according to the present invention is used for a display device with a touch panel function in which an input operation is performed by detecting the position of an object close to the panel surface by having an image capturing function. However, the use of the liquid crystal display element of the present invention is not limited to this, and an information display terminal having a scanner function and an image display function capable of displaying an image captured using the image capture function on the spot. As the display element, a wide range of uses such as a display element of a bidirectional communication display device having an image display function and an imaging function is assumed.

  In addition, each figure referred below demonstrates the simplified main component required in order to demonstrate this invention among the structural members of embodiment of this invention for convenience of explanation. Therefore, the display apparatus according to the present invention can include arbitrary constituent members that are not shown in each of the referenced drawings. Moreover, the dimension of the member in each figure does not represent the dimension of an actual structural member, the dimension ratio of each member, etc. faithfully. In particular, in order to explain each layer formed on the back substrate of the liquid crystal display element, the dimension in the thickness direction is enlarged and displayed.

[First Embodiment]
FIG. 1 is a cross-sectional configuration diagram showing a schematic configuration of a liquid crystal panel 1 having a touch panel function, which is a liquid crystal display element according to a first embodiment of the present invention. In FIG. 1, the left side shows a state where an image display function is achieved, and the right side shows a state where a function as a touch panel is achieved.

  As shown in FIG. 1, the liquid crystal panel 1 according to the present embodiment is configured by sandwiching a liquid crystal layer 4 between two substrates, a front substrate 2 and a rear substrate 3 made of a transparent material such as glass. On the inner surface of the front substrate 2, a color filter 5 for image display is formed. The color filter 5 is painted in three colors of RGB for each pixel which is a unit of image display in the liquid crystal panel 1. In the liquid crystal panel 1, the color transmittance is controlled by controlling the light transmittance of the liquid crystal layer 4 in each pixel to display a color image.

  A light shielding film 8 is formed on the inner surface of the back substrate 3, and a photodiode 7, which is a light receiving element, is formed thereon via a base layer (not shown). The light-shielding film 8 is for shielding the irradiation light 10 from the backlight 9 described later so as not to directly enter the photodiode 7. The back substrate 3 is provided with a TFT as a switching element for applying a predetermined electric field to the liquid crystal layer 4 at a position corresponding to each pixel, and for applying a predetermined voltage to the TFT. The wiring electrodes such as the gate wiring and the source wiring are formed, but are not shown in FIG.

  An insulating layer 6 is formed on the photodiode 7, the TFT, and each wiring electrode. Although this insulating layer 6 is shown as one layer in FIG. 1 for convenience, it is actually composed of a plurality of insulating films such as an interlayer insulating film and a planarizing film. The interlayer insulating film is an insulating film for ensuring insulation between circuit elements such as the photodiodes 7 and TFTs and electrode lines such as source wiring. In addition, the planarization film functions as a protective film for protecting circuit elements such as photodiodes from a rubbing process when forming an alignment film (not shown), and because circuit elements and electrode wirings are formed. It has the role of absorbing the generated fine irregularities and making the height from the back substrate 3 up to the portion facing the liquid crystal layer 4 uniform. This planarization film is sometimes called a passivation film. Note that these circuit elements, electrode wirings, and the detailed configuration of each insulating film will be described in detail later.

  Further, on the insulating layer 6, as a pixel electrode for applying a predetermined voltage to the portion of the liquid crystal layer 4 corresponding to each pixel, transmission is performed for displaying an image using the irradiation light 10 from the backlight 9. A transparent electrode such as an ITO film formed in the region and a reflective electrode such as an aluminum film formed in the reflective region that reflects external light and contributes to image display are formed, but are not shown in FIG. To do.

  On the back surface of the liquid crystal panel 1, a backlight 9, which is a planar light source, is disposed that emits irradiation light 10 for transmitting images through the liquid crystal layer 4 of the liquid crystal panel 1. The backlight 9 can irradiate light such as a cold cathode fluorescent tube or an LED as a light source with a uniform color and luminance in a planar shape using an optical sheet or a light guide plate.

  As shown on the left side of FIG. 1, when an image is displayed on the liquid crystal panel 1 according to the present embodiment, the irradiation light 10 from the backlight 9 is transmitted through the liquid crystal panel 1, and the front substrate 2 and the back surface are displayed. A predetermined gradation is given to each pixel, which is a unit of image display, by a polarizing action in a pair of polarizing plates (not shown) provided on the outside of the substrate 3 and the liquid crystal layer 4. This is viewed as an image.

  In the case of functioning as the touch panel shown on the right side of FIG. 1, the reflected light that is irradiated from the backlight 9, passes through the liquid crystal panel 1, and then strikes the finger 12 of the instructor outside the front panel 2 is reflected in the photo The position of the finger 12 is detected by detecting with the diode 7. In the photodiode 7, not only the reflected light of the irradiation light 10 emitted from the backlight 9 described above but also the luminance change when the external light incident on the liquid crystal panel 1 from the outside is blocked by the finger 12 of the instructor. Therefore, both of these changes in light can be used for detecting the position of the finger 12 of the instructor.

  Next, the configuration on the back substrate of the liquid crystal panel 1 having a touch panel function according to the present embodiment will be described. FIG. 2 is a diagram showing a state in which the inner surface side of the rear substrate 3 of the liquid crystal panel 1 according to the present embodiment, that is, the side facing the liquid crystal layer is viewed from the front substrate side.

  In FIG. 2, a region indicated by a two-dot chain line 21 is a portion corresponding to one pixel. Therefore, in FIG. 2, in the case of a color image display, three pixels corresponding to RGB and the surrounding configuration are shown. Corresponding to the arrangement of the pixels 21 arranged in the row direction (lateral direction), four wiring electrodes of the gate wiring 22, the common wiring 23, the light receiving element drive line 24, and the light reception data output line 25 are formed in the row direction of the pixel 21. Has been. Among these, the gate wiring 22 and the common wiring 23 are wiring related to the image display function, and the light receiving element driving line 24 and the light receiving data output line 25 are wiring related to the sensor function as a touch panel using the light receiving element. It is. A source wiring 26 is formed between the pixels 21 corresponding to the arrangement of the pixels 21 arranged in the column direction (vertical direction).

  Corresponding to the pixel 21 portion, a pixel electrode 27 for applying a voltage to the liquid crystal layer is formed via an insulating layer (not shown). In the liquid crystal panel 1 according to the present embodiment, the pixel electrode 27 is formed by partially laminating a reflective electrode 29 made of a highly reflective metal such as aluminum on a transparent electrode 28 made of a transparent conductive film such as ITO. Has been. A portion of the pixel electrode 27 where only the transparent electrode 28 is formed becomes a transmissive region for displaying an image by transmitted light from a backlight (not shown).

  Corresponding to each pixel 21, a TFT 30, which is a switching element that applies a voltage for performing a predetermined gradation display on a liquid crystal layer (not shown) to the pixel electrode 27 is formed. The gate electrode of the TFT 30 is connected to the gate wiring 22, and the source electrode is connected to the source wiring 26. Note that an auxiliary capacitance portion 31 for stabilizing the driving of the TFT 30 is formed so as to overlap the common wiring 23.

  In the portion where the TFT 30 and the auxiliary capacitance portion 31 are formed, that is, the portion between the gate wiring 22 and the common wiring 23, the reflective electrode 29 as the pixel electrode 27 is formed by being laminated on the transparent electrode 28. Has been. The liquid crystal panel 1 according to the present embodiment reflects external light that is transmitted through a front panel (not shown) by the reflective electrode 29 and can use this reflected light for image display. Therefore, even when the backlight is turned off, the image display is performed. In an environment where sufficient external light can be obtained, the input power to the backlight can be reduced. Therefore, it is particularly suitable as an image display element used for mobile devices.

  In the sensor function portion as the touch panel, one light receiving element is arranged for each of the three pixels shown in FIG. The photodiode 7 which is a light receiving element is formed so as to overlap the light shielding film 8 formed on the back side thereof, and one end thereof is connected to the light receiving element drive line 24. The other end of the photodiode 7 is connected to a drive transistor unit 33 that drives the photodiode 7 through a capacitor unit 32 that stores electric charges.

  In the liquid crystal panel 1 according to the present embodiment, when the rear substrate 3 is viewed from the front substrate side (not shown), the light receiving region 52 is surrounded around the light receiving region 52 of the photodiode 7 that is a light receiving element. In addition, a reflective film 34 is formed on the side wall of the opening of the second insulating film.

  Next, the circuit elements formed on the back substrate 3 of the liquid crystal panel according to the present embodiment and the cross-sectional structure of each layer will be described with reference to FIG. In addition, about the film thickness of each layer in the following description, and the material to comprise, it is an illustration to the last and does not become a restriction | limiting on application of this invention.

  FIG. 3 shows a cross-sectional structure of a portion where the photodiode 7 as a light receiving element is formed in the liquid crystal panel according to the present embodiment. In FIG. 2, this is a portion corresponding to the region indicated by the alternate long and short dash line A.

  As shown in FIG. 3, a light shielding film 8 made of a metal such as molybdenum and having a thickness of about 100 nm is formed on the inner surface of a back substrate 3 made of a transparent material substrate such as glass. The light shielding film 8 is formed in a portion where the photodiode 7 is formed later by patterning a metal film deposited by sputtering using a photolithography method or the like. The light shielding film 8 performs a light shielding function for preventing light emitted from the backlight from being incident on the photodiode 7 so that the photodiode 7 is always in an excited state.

  A base coat 41, which is a base film composed of a silicon nitride film having a thickness of 100 nm and a silicon dioxide film having a thickness of 100 nm, is formed on at least the entire surface of the back substrate 3 including the patterned light shielding film 8 where image display is performed. Has been. The base coat 41 can be formed by depositing a silicon film by a plasma CVD method.

  A semiconductor layer to be the photodiode 7 is formed on the base coat 41 in a portion overlapping the light shielding film 8. In addition, a semiconductor layer to be the TFT 30 is formed in a predetermined portion that does not overlap with the light shielding film 8. This semiconductor layer is formed by depositing amorphous silicon to a thickness of 50 nm, forming polysilicon by laser annealing or the like, and then patterning.

  The photodiode 7 includes a p-type semiconductor region (P layer) 51 and an n-type semiconductor sandwiching an intrinsic semiconductor region (I layer) 52 which is a central region intrinsic semiconductor or a region into which a small amount of impurities are introduced. The region (N layer) 53 is formed. On the other hand, the semiconductor layer in the TFT 30 has a lightly doped drain region 62, a heavily doped drain region 61 on the outside, a lightly doped source region 64, and a heavily doped source region 65 on the outside, on both sides of the central channel region 63. It has become.

  A gate insulating film 42 made of a silicon dioxide film having a thickness of 100 nm is formed on the photodiode 7 and the TFT 30. A gate electrode 66 is formed on the gate insulating film 42 in the region where the TFT 30 is formed.

  On the gate insulating film 42 and the gate electrode 66, an interlayer insulating film 43 is formed in which a silicon nitride film having a thickness of 300 nm and a silicon dioxide film having a thickness of 500 nm are stacked. Through the contact hole formed in the interlayer insulating film 43, the anode electrode 54 and the cathode electrode 55 are formed in the portion where the photodiode 7 is formed. In the TFT 30 portion, a drain electrode 67 and a source electrode 68 are formed.

  In the portion of the interlayer insulating film 43 that overlaps the light receiving region 52 of the photodiode 7, the interlayer insulating film 43 is removed by, for example, anisotropic etching, and an opening 56 is formed. As shown in FIG. 3, the side wall of the opening 56 has an inclined surface 57 that is wide on the upper side and narrow on the lower side, and a reflective film 34 made of a metal film is formed on the inclined surface 57. The reflective film 34 is formed of the same material as the anode electrode 54 and the cathode electrode 55 of the photodiode 7 described above, so that it is not necessary to provide a separate manufacturing process for the reflective film 34. Is preferred.

  On the interlayer insulating film 43, its opening 56, and various electrodes formed on the interlayer insulating film 43, a planarizing film 44 made of a photocurable resin having a thickness of 2.5 μm is formed. .

  On the planarizing film 44, a transparent electrode 28 patterned with an ITO film having a thickness of 100 nm, and a reflective electrode 29 made of an aluminum film having a thickness of 100 nm laminated on the transparent electrode 28 in a portion where the TFT 30 is formed. Is formed. The transparent electrode 28 and the reflective electrode 29 constitute a pixel electrode 27. The reflective electrode 29 and the transparent electrode 28 are connected to the drain electrode 68 of the TFT 30 through a contact 69 formed in the contact hole of the interlayer insulating film 44.

  Note that a liquid crystal layer is formed further above the pixel electrode through an alignment film, but the illustration and detailed description in FIG. 3 are omitted.

  In the liquid crystal panel 1 according to the present embodiment, as shown in FIG. 3, the opening 56 is formed by removing the interlayer insulating film 43 at a portion on the light receiving region 52 of the photodiode 7. Then, by setting the side wall of the opening 56 to an inclined surface 57 having a wide upper side and a narrow lower side, the external light 13 that has been transmitted through a front substrate (not shown) and incident by the reflective film 34 formed on the inclined surface 57. Can be reflected and incident on the light receiving region 52 of the photodiode 7. By doing in this way, the external light 13 which injects into the light reception area | region 52 of the photodiode 7 can be increased, and the light reception sensitivity of the photodiode 7 can be improved substantially.

  The inclination angle α of the side wall in the opening 56 of the interlayer insulating film 43 is appropriately determined in consideration of the relationship between the size of the opening 56 and the thickness of the interlayer insulating film 43, etc., but is 45 degrees or more. It is preferable that the light receiving efficiency can be maximized at about 60 to 70 degrees. 3 shows a state in which the interlayer insulating film 43 is completely removed at the opening 56 of the interlayer insulating film 43, but the interlayer insulating film 43 is slightly formed on the photodiode 7 at the bottom of the opening 56. You can leave as much as the thickness.

[Second Embodiment]
Next, as a second embodiment of the liquid crystal display element of the present invention, an example in which a reflective film is formed at a site different from that described in the first embodiment will be described. In the first embodiment and the second embodiment, the reflective film formation site and the pixel electrode structure are different, but the configuration of the other parts is the same, so the description will focus on the parts that are different in the configuration. The description of the parts having the same configuration is omitted as appropriate.

  FIG. 4 is a diagram illustrating a state in plan view from the front substrate side of the inner surface side of the rear substrate 3 of the liquid crystal panel 1 according to the second embodiment of the present invention.

  Also in FIG. 4, as in FIG. 2, a region indicated by a two-dot chain line 21 corresponds to one pixel. In the second embodiment shown in FIG. 4, in each pixel 21, a transparent electrode of a portion related to a sensor function as a touch panel using a light receiving element, sandwiched between a light receiving element driving line 24 and a light receiving data output line 25. 2 is different from the first embodiment shown in FIG. 2 in that a second reflective electrode 29b made of an aluminum film is also laminated on the layer 28.

  When an image display is performed using light emitted from a backlight with a sensor function part that performs an image capturing function as a transmission region, the light shielding film 8 and the photodiode 7 formed in the sensor function part are driven. Irradiated light from the backlight is blocked at a part where circuit components such as the capacitor part 32 are formed. For this reason, if this sensor function portion is used to display an image as a transmission region, a decrease in the aperture ratio is inevitable. However, as in the case of the present embodiment, by providing the second reflective electrode 29b, the sensor function part excluding the light receiving area forming part of the photodiode as the light receiving element is actively contributed to the image display as the reflective area. Can be made. Therefore, it is possible to solve the problem that substantial image display cannot be performed with the entire sensor function portion, and to improve the ratio of the area in the pixel 21 where image display is possible.

  In the liquid crystal panel according to the second embodiment, when the rear substrate 3 is viewed from the front substrate side (not shown), the light receiving region 52 is surrounded around the light receiving region 52 of the photodiode 7 that is a light receiving element. As described above, the reflective film 35 is formed on the side wall of the opening of the planarizing film.

  FIG. 5 shows a cross-sectional structure of a portion where a photodiode 7 as a light receiving element is formed in the liquid crystal panel according to the second embodiment. That is, it is a view corresponding to FIG. 3 in the description of the first embodiment, and shows a region indicated by a one-dot chain line B in FIG.

  Also in the liquid crystal panel according to the second embodiment shown in FIG. 5, the light shielding film 8 is formed on the back substrate 3, the base coat 41 as the underlayer is formed on the light shielding film 8, and further, A semiconductor layer that becomes the photodiode 7 as a light receiving element, a semiconductor layer that becomes the TFT 30, a gate insulating film 42, and a gate electrode 56 are sequentially formed.

  In the liquid crystal panel according to the second embodiment, no opening is formed in the portion of the interlayer insulating film 43 that is the second insulating film that overlaps the light receiving region 52 of the photodiode 7. Instead, an opening 57 is formed in the planarization film 44 formed further above the interlayer insulating film 43 and various electrodes formed on the interlayer insulating film 43. The side wall of the opening 57 has an inclined surface 58 that is wide on the upper side and narrow on the lower side, and a reflective film 35 made of a metal film is formed on the inclined surface 58.

  By forming the reflective film 35 with the same material as the reflective electrode 29 and the second reflective electrode 29b described later, it is not necessary to newly provide a process for manufacturing the reflective film 35.

  A transparent electrode 28 made of an ITO film is formed on the flattening film 44, and a reflective electrode 29 made of an aluminum film laminated on the transparent electrode 28 is formed in a portion where the TFT 30 is formed, and a portion where the photodiode 7 is formed Then, the second reflective electrode 29b, which is also made of an aluminum film, is formed. The reflective electrode 29 and the transparent electrode 28 are connected to the drain electrode 68 of the TFT 30 through a contact 69 formed in the contact hole of the interlayer insulating film 44. The second reflective electrode 29 b is connected to the drain electrode 68 through the transparent electrode 28. In the present embodiment, the pixel electrode 27 is not formed in the portion of the opening 57 formed in the planarizing film 44.

  Also in FIG. 5, illustration and detailed description of the alignment film and the liquid crystal layer are omitted.

  In the liquid crystal panel 1 according to the present embodiment, as shown in FIG. 5, an opening 57 is formed in the planarizing film 44 at a portion on the light receiving region 52 of the photodiode 7. Then, by making the side wall of the opening 57 the inclined surface 58 having a wide upper side and a narrow lower side, the external light 13 that has entered the front substrate (not shown) is incident by the reflective film 35 formed on the inclined surface 58. Can be reflected and incident on the light receiving region 52 of the photodiode 7. By doing in this way, the external light 13 which injects into the light reception area | region 52 of the photodiode 7 can be increased, and the light reception sensitivity of the photodiode 7 can be improved substantially.

  In general, since the planarization film 44 is thicker than the interlayer insulating film 43, in the second embodiment, the external light 13 is applied to the light receiving region 52 of the photodiode 7 as compared with the first embodiment. The area of the reflective film 35 to be reflected can be enlarged. For this reason, more external light 13 can be reflected to the light receiving region 52.

  Note that the inclination angle β of the side wall of the opening 57 of the planarizing film 44 is also appropriately determined in consideration of the relationship between the size of the opening 57 and the thickness of the planarizing film 44. Similar to the inclination angle α of the side wall of the opening 56 of the interlayer insulating film 43 shown in FIG. 3, it is preferably 45 degrees or more, and about 60 to 70 degrees is the most efficient. FIG. 5 also shows a state in which the planarization film 44 is completely removed at the opening 57 of the planarization film 44, but even if a little planarization film 44 remains at the bottom of the opening 57. The points that do not matter are the same as in the first embodiment.

  In the present embodiment, since the opening 57 is formed in the planarizing film 44, the alignment film (not shown) is disturbed in the opening 57, and the thickness of the liquid crystal layer (not shown) is also different. The alignment state of the liquid crystal molecules may be disturbed. However, since the size of the opening 57 is very small, and the pixel electrode 27 is not formed in the portion where the opening 57 is formed, the image display in this portion is not actually performed. The influence on the display image of the liquid crystal panel can be almost ignored.

  In order to completely avoid the influence of the opening 57 on the display image, a filling member 59 such as a transparent resin is injected into the opening 57 as shown in FIG. 6 as an application example of the second embodiment. Then, the surface may be leveled with the surface of the planarizing film 44. In this case, it is conceivable to form the auxiliary reflection film 36 on the surface of the filling member 59 at a position overlapping the light receiving region 52 of the photodiode 7. By appropriately selecting the size of the auxiliary reflecting film 36, as shown in FIG. 6, the light reflected by the reflecting film 37 formed on the inclined surface 58 which is the side wall of the opening 57 of the planarizing film 44 is reflected. The external light 13 that has not been directed to the light receiving region 52 side of the photodiode 7 can be reflected toward the light receiving region 52. Thus, by providing the auxiliary reflection film 36, the substantial light receiving sensitivity of the photodiode 7 which is a light receiving element can be further improved.

[Third Embodiment]
Next, as a third embodiment of the liquid crystal display element of the present invention, an example in which a reflective film is formed in another part different from those described in the first and second embodiments will be described. To do. In the third embodiment, the configuration of the pixel electrode is the same as that of the first embodiment, and the positional relationship in the plan view of the position where the reflective film is formed is also the same as in FIG. . For this reason, in 3rd Embodiment, the description using a top view is abbreviate | omitted.

  FIG. 7 is a diagram showing a cross-sectional structure of a portion where the photodiode 7 is formed in the liquid crystal panel according to the third embodiment.

  The liquid crystal panel according to the third embodiment shown in FIG. 7 is different from the first and second embodiments described above in that a reflective film 37 is provided on the back surface of the photodiode 7 that is a light receiving element. In the present embodiment, no opening is formed in the interlayer insulating film 43 or the planarizing film 44.

  Specifically, in the present embodiment, a recess 14 is formed in advance at a position overlapping the position where the photodiode 7 of the back substrate 3 is formed, and the light shielding film 8 is formed on the inclined surface 15 that is the side wall of the recess 14. A reflective film 37 is also formed. To be precise, the concave portion 14 is first formed on the back substrate 3, the reflective film 37 also serving as the light shielding film 8 is formed thereon, and further the base coat film 41 is formed, and then the light receiving region 52 of the photodiode 7. A certain intrinsic semiconductor region is formed so as to accurately overlap the central portion of the recess 14 formed in the back substrate 3. In this way, the reflection film 37 formed on the inclined surface 15 that is the side wall of the recess 14 can be positioned around the light receiving region 52 when viewed from the front substrate side.

  In the present embodiment, the light shielding film 8 also functions as a reflection film 37 that reflects the external light 13 incident on the liquid crystal panel to the light receiving region of the photodiode 7. For this reason, it is preferable that the reflectance of the surface is high, and it is preferable to use a dark-colored metal thin film such as molybdenum that has both light shielding properties and surface reflectivity.

  Thus, by forming the reflective film 37 on the back side of the photodiode 7, the external light 13 that is incident on the region where the photodiode 7 is formed but is not incident on the intrinsic semiconductor region that is the light receiving region 52. Can be received by the light receiving region 52. As a result, the substantial light receiving sensitivity of the photodiode as the light receiving element can be improved.

  In the present embodiment, the case where one metal film serves as both the light shielding film 8 and the reflective film 37 has been described. However, the present invention is not limited to this, and the light shielding property is first applied to the recess 14 formed in the back substrate 3. It is also possible to adopt a two-layer structure in which a light-shielding film excellent in the above is formed and a film excellent in light reflectivity is laminated thereon to form a reflective film.

  As described above, in the first to third embodiments of the liquid crystal display element according to the present invention, when the shape of the reflective film is viewed from the front substrate side, the entire periphery of the light receiving region of the photodiode that is the light receiving element. It has been described as surrounding. However, the reflective film in the present invention is not limited to the one that surrounds the entire periphery of such a light receiving region. In FIG. 2 and FIG. 4 showing the state in plan view, a reflective film may be provided in a region that sandwiches the light receiving region 52 from the left and right or up and down directions, and the reflective film is provided only in one of the up, down, left and right directions. It may be.

  In each of the above embodiments, the reflective film is provided on the inclined surface of the opening of the insulating film or the concave portion of the back substrate. However, the present invention is not limited to this, and the bottom of the reflective film faces the back substrate side. It can also be a bowl-shaped object, that is, a curved surface. Furthermore, it is not essential to provide an opening in the insulating film or a recess in the back substrate. In short, a surface that reflects external light toward the light receiving area is formed at least around the light receiving area. Needless to say, if it can be done, the formation method is not limited.

  Furthermore, the configuration of the reflective film shown in each embodiment is not used alone, but a plurality of embodiments can be appropriately selected and used in duplicate. For example, an opening is formed in the interlayer insulating film and the first reflective film is formed on the inclined surface. Further, an opening is formed in the planarizing film and the second reflective film is formed on the inclined surface. That is, the first embodiment and the second embodiment can be used simultaneously. In this case, since the reflective film formation region is further enlarged and the reflective film area is increased, most of the external light incident near the light receiving element formation region can be reflected and received by the light receiving region. Further improvement in light receiving sensitivity can be expected.

  Further, the formation position of the reflective film is not limited to any of the back substrate, the interlayer insulating film, and the planarizing film in the thickness direction of the back substrate, and the reflected external light is incident on the light receiving region of the light receiving element. It can be formed at any position that does not cause a harmful effect of image display.

  If the liquid crystal display element does not have a transmissive area and displays an image only by the reflection method, it is not necessary to irradiate irradiation light from the back side of the liquid crystal display element, so a light shielding film is formed on the back side of the light receiving element. Of course, you don't have to. In each embodiment of the present invention, the surface of the reflective electrode may be provided with a concavo-convex shape. In this case, the reflection angle of the external light is scattered to give the display image in the reflective region more directivity than necessary. The effect of not having it is obtained.

  Further, in the description of each of the above embodiments, the top gate type TFT using polysilicon is exemplified as the TFT of the liquid crystal display element. However, in the present invention, the TFT type does not affect its function and effect. Needless to say, it is not limited to. Various TFTs including bottom gate type can be used. Similarly, the photodiode is not limited to the illustrated PIN type, and there is no problem with the PN type, and the light receiving element is not limited to the photodiode.

[Fourth Embodiment]
Next, an outline of a liquid crystal display device with a touch panel function using the liquid crystal display element according to the present invention will be described as a fourth embodiment of the present invention.

  FIG. 8 is a block diagram showing a schematic configuration of the liquid crystal display device according to the present invention. The liquid crystal display device 100 according to the present invention includes the liquid crystal display element 1 described as the first to third embodiments, the backlight 9, and various circuits for performing an image display function and a sensor function as a touch panel. It is configured.

  The liquid crystal display device 100 according to the present embodiment includes a drive control unit 71, a vertical drive circuit 72, and a horizontal drive circuit 73 as an image display control circuit unit for performing an image display function.

  The drive control unit 71 converts the input image signal into a vertical drive signal and a horizontal drive signal for performing image display, and outputs them. Based on this vertical drive signal, the vertical drive circuit 72 connected to the gate wiring of the liquid crystal display element 1 and sequentially selecting it operates. In addition, the horizontal drive circuit 73 inputs a predetermined luminance signal to a TFT (not shown) through a source line to each of the pixels 21 connected to the gate lines sequentially selected by the vertical drive circuit unit 72. Based on the gradation signal input from the horizontal drive circuit 73, the transmittance of the liquid crystal layer is changed in each pixel 21, and the transmittance of the irradiation light 10 emitted from the backlight 9 is changed to display an image. To do.

  In addition, the liquid crystal display device 100 according to the present embodiment includes a detection control unit 74, a vertical detection circuit 75, and a horizontal detection circuit 76 as detection control circuit units in order to perform a sensor function as a touch panel. .

  The detection control unit 74 outputs a vertical detection signal and a horizontal detection signal for driving the photodiode 7 which is a light receiving element arranged in the pixel 21 to read out a luminance signal. The vertical detection circuit 75 to which the vertical detection signal is input and the vertical detection circuit 76 to which the horizontal detection signal is input drive a predetermined photodiode 7, and the luminance signal obtained at this time is output from the vertical detection circuit 75 as a sensor output. The signal is transmitted to the detection control unit 74 as a signal. The detection control circuit 74 detects the position of the finger of the indicator on the liquid crystal display element 1 from the sensor output signal and outputs it as a touch panel signal.

  Note that the circuit configuration shown in FIG. 8 is only a general embodiment of the present invention, and is limited to the exemplified configuration in order to perform any of the image display function and the function as a touch panel sensor. It goes without saying that it is not a thing.

  The present invention relates to a liquid crystal display element with a sensor function capable of capturing an image having a light receiving element in a pixel, and a liquid crystal display device including this element, and in particular, a liquid crystal display element with improved light receiving efficiency in the light receiving element In addition, it can be used industrially as a liquid crystal display device.

It is a section lineblock diagram showing a schematic structure of a liquid crystal display element concerning an embodiment of the present invention. It is a principal part enlarged plan view when the back substrate of the liquid crystal display element concerning the 1st Embodiment of this invention is planarly viewed from the front substrate side. It is a principal part cross-section block diagram of the liquid crystal display element concerning the 1st Embodiment of this invention. It is a principal part enlarged plan view when the back substrate of the liquid crystal display element concerning the 2nd Embodiment of this invention is planarly viewed from the front substrate side. It is a principal part cross-section block diagram of the liquid crystal display element concerning the 2nd Embodiment of this invention. It is a principal part cross-section block diagram which shows the application example of the display element concerning the 2nd Embodiment of this invention. It is principal part sectional block diagram of the liquid crystal display element concerning the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the liquid crystal display device concerning this invention.

Explanation of symbols

1. Liquid crystal panel (liquid crystal display element)
2 Front substrate 3 Back substrate 4 Liquid crystal layer 6 Insulating layer 7 Photodiode (light receiving element)
13 External light 27 Pixel electrode 34, 35, 37 Reflective film 41 Base film (base coat)
43 Interlayer insulating film 44 Planarizing film 52 Light receiving region

Claims (9)

A liquid crystal layer sandwiched between a front substrate and a rear substrate;
A light receiving element provided on a base layer provided on the back substrate;
A pixel electrode provided on an insulating layer provided on the light receiving element,
When viewed in plan from the front substrate side, a reflection film is formed on at least a part of the periphery of the light receiving region of the light receiving element to reflect external light that is transmitted through the front substrate toward the light receiving region. A liquid crystal display element characterized by comprising:   The reflective film is formed on an inclined surface which is a side wall of an opening formed in an interlayer insulating film constituting the insulating layer formed between the light receiving element and an electrode connected to the light receiving element. The liquid crystal display element according to claim 1.   The liquid crystal display element according to claim 2, wherein the reflective film is a metal film made of the same material as an electrode connected to the light receiving element formed on the interlayer insulating film.   The reflection film is an inclination that is a side wall of an opening formed in the planarization film that constitutes the insulating layer formed between the light receiving element and the electrode connected to the light receiving element and the pixel electrode The liquid crystal display element according to claim 1, wherein the liquid crystal display element is formed on a surface.   The liquid crystal display element according to claim 4, wherein at least a part of the pixel electrode is a reflective electrode that reflects external light, and the reflective film is a metal film made of the same material as the reflective electrode.   The concave portion is formed at a position overlapping the light receiving region of the rear substrate when viewed from the front substrate side, and the reflective film is formed on an inclined surface that is a side wall of the concave portion. The liquid crystal display element according to any one of 5.   The light shielding film is provided between the said back substrate and the said base layer of the position which overlaps with the said light receiving element when planarly viewed from the said front substrate side. Liquid crystal display element.   The liquid crystal display element according to claim 7, wherein the light shielding film also serves as the reflective film. A liquid crystal display element according to any one of claims 1 to 9,
An image display control circuit unit for displaying an image on the liquid crystal display element;
A liquid crystal display device comprising: a detection control circuit unit for driving the light receiving element to output a light reception signal.

Images