JP2008170460A - Active matrix substrate, display device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent sensitivity failure and characteristic deterioration with time, due to deterioration of a surface protection film provided on an upper layer of the environmental sensor in a display device provided with the environmental sensor formed in the peripheral region of the active matrix substrate. <P>SOLUTION: In the active matrix substrate having a pixel arrangement region wherein a plurality of pixels is arranged and the peripheral region around the pixel arrangement region on the same substrate and the surface protection film arranged on the upper layer of the arrangement layer of the environmental sensor in the peripheral region, the surface protection film is provided with an opening section at a portion equivalent to an upper portion of the arrangement position of the environmental sensor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a display device such as a liquid crystal display device and an EL (Electronic Luminescent) display device. The present invention also relates to an active matrix substrate used for these display devices.

  Flat panel display devices, typified by liquid crystal display devices, have features such as thin and light weight and low power consumption. Furthermore, technological development is progressing to improve display performance such as colorization, high definition, and video compatibility. Therefore, it is currently incorporated into a wide range of information devices such as mobile phones, PDAs (Personal Digital Assistants), DVD players, mobile game devices, notebook PCs, PC monitors, TVs, and other electronic devices such as TV devices and amusement devices. ing.

  In such a background, a technique for attaching an environmental sensor for detecting a surrounding environment to a display device has begun to be used. A typical example of this environmental sensor is an optical sensor that detects the brightness of the surrounding environment. In recent years, display systems with an automatic dimming function that automatically control the brightness of the display device according to the brightness of the use environment have been proposed for the purpose of further improving the visibility of the display device and reducing power consumption. .

  A display system including such an optical sensor is disclosed in, for example, Patent Document 1 and Patent Document 2. In Patent Document 1 and Patent Document 2, there is a method in which an optical sensor, which is a discrete component, is disposed in the vicinity of a display device, and the brightness of the display device is automatically controlled based on the use environment illuminance detected by the optical sensor. It is disclosed. As a result, the brightness is automatically adjusted (adjusted) according to the brightness of the surrounding environment, such as increasing the display brightness in a bright environment such as daytime or outdoors, and decreasing the display brightness in a relatively dark environment such as nighttime or indoors. Light). In this case, an observer of the display device does not feel the screen dazzling in a dark environment, and the visibility can be improved. In addition, it is possible to realize lower power consumption and longer life of the display device as compared with the usage method in which the display luminance is always kept high regardless of the brightness / darkness of the usage environment. Furthermore, since the brightness adjustment (dimming) is automatically performed based on the detection information of the optical sensor, the user's hand is not bothered.

  In this way, a display system equipped with an automatic light control function can achieve both good visibility and low power consumption against changes in the brightness of the usage environment, so there is an opportunity to take it outdoors and use it. This is particularly useful for mobile devices (cell phones, PDAs, mobile game devices, etc.) that require many battery drives.

  On the other hand, Patent Document 3 discloses a structure in which an optical sensor, which is a discrete component, is incorporated in a display device as an example of a structure in which an environmental sensor is incorporated in a display device. FIG. 13 is a schematic configuration diagram excluding the casing of the liquid crystal display device disclosed in Patent Document 3, and FIG. 14 is a cross-sectional view of the photosensor mounting portion.

  This liquid crystal display device has a structure in which a substrate (active matrix substrate) 901 on which an active element such as a thin film transistor (TFT) is formed and a counter substrate 902 are bonded together, and a liquid crystal layer 903 is sandwiched between the substrates. Here, an optical sensor 907, which is a discrete component, is disposed in the peripheral portion of the active matrix substrate 901, that is, in the peripheral region S (frame region) where the counter substrate does not exist. Further, a backlight system 914 is provided on the side of the active matrix substrate 901 opposite to the side on which the counter substrate 902 is disposed. A housing 915 is disposed so as to cover the side of the backlight system 914 that faces the active matrix substrate 901 and the periphery of the peripheral region S. An opening 916 is provided at a position facing the optical sensor 907 of the housing 915, and light to the optical sensor 907 enters from the opening 916.

  Thus, the structure in which the optical sensor 907 is disposed in the peripheral region S has the following characteristics. That is, when the display mode of the liquid crystal display device is a transmissive type or a transflective type, it is necessary to provide a backlight system on the back surface of the active matrix substrate 901, but the optical sensor 907 is disposed in the peripheral region S. Therefore, the light emitted from the backlight system 914 does not directly reach the light sensor 907, and the malfunction of the light sensor 907 due to the light emitted from the backlight system can be minimized. . In a normal liquid crystal display device, a polarizing plate (not shown) is attached to the front side of the counter substrate 902. However, since the optical sensor 907 is disposed in the peripheral region, the optical sensor 907 Incident external light is not blocked by the polarizing plate on the counter substrate 902, and a sufficient amount of external light can be guided to the photosensor. As a result, the optical sensor 907 can obtain a high S / N.

  On the other hand, in recent years, display device manufacturing technology has rapidly advanced, and IC chips and various circuit elements that have been mounted as discrete components in the periphery of the display device in the past can be displayed when forming the constituent circuits and elements of the display device. There has been established a technique for forming monolithically by the same process in an apparatus (specifically, on a glass substrate constituting a display device).

  For example, in Patent Document 4, when forming a display area portion on a substrate, a vertical drive circuit, a horizontal drive circuit, a voltage conversion circuit, a timing generation circuit, an optical sensor circuit, and the like are the same in an area around the display area portion. An example of forming a monolithic process is disclosed. Such monolithic formation of discrete components in the display device enables the number of components and the component mounting process to be reduced, and downsizing and cost reduction of an electronic device incorporating the display device can be realized. Needless to say, the above-described optical sensor used for luminance adjustment (dimming) of the display device, a dedicated circuit for the optical sensor (light amount detection circuit), and the like can be monolithically formed in the display device. Patent Document 3 also describes a technique in which a peripheral circuit and an optical sensor are monolithically formed on a substrate in the same process instead of a discrete component optical sensor.

  Incidentally, as an active element used in an active matrix display device, a thin film transistor (TFT) using an amorphous Si film or a polycrystalline Si film is generally used. As described above, when an active element and various circuit elements are formed monolithically on the same substrate, a TFT using a polycrystalline Si film is mainly used.

  A structure of a TFT including a polycrystalline Si film formed in each pixel in the pixel array region (display region) as a semiconductor layer will be described with reference to FIG. The TFT structure described here is called a “top gate structure” or “positive stagger structure”, and includes a gate electrode on a semiconductor film (polycrystalline Si film) serving as a channel.

  The TFT 500 includes a polycrystalline Si film 511 formed on the glass substrate 510, a gate insulating film 512 formed so as to cover the polycrystalline Si film 511, a gate electrode 513 formed on the gate insulating film 512, A first interlayer insulating film 514 formed to cover the gate electrode 513 and the gate oxide film 512. The source electrode 517 formed on the first interlayer insulating film 514 is electrically connected to the source region 511c of the semiconductor film through a contact hole that penetrates the first interlayer insulating film 514 and the gate insulating film 512. . Similarly, the drain electrode 515 formed on the first interlayer insulating film 514 is electrically connected to the drain region 511b of the semiconductor film through a contact hole that penetrates the first interlayer insulating film 514 and the gate insulating film 512. Has been. Further, a second interlayer insulating film 518 is formed so as to cover them.

  In such a structure, a region of the semiconductor film facing the gate electrode 513 functions as the channel region 511a. The regions other than the channel region 511a of the semiconductor film are doped with impurities at a high concentration, and function as the source region 511c and the drain region 511b.

  Although not shown here, LDD (Lightly Doped Drain) in which impurities are doped at a low concentration on the channel region side of the source region 511c and the channel region side of the drain region 511b in order to prevent deterioration of electrical characteristics due to hot carriers. A region is formed.

  Further, a pixel electrode 519 for supplying an electric signal to the driven display medium is formed on the second interlayer insulating film 518. The pixel electrode 519 is electrically connected to the drain electrode 515 through a contact hole provided in the second interlayer insulating film 518. In general, the pixel electrode 519 is often required to have flatness, and the second interlayer insulating film 518 existing below the pixel electrode 519 is required to function as a flattening film. Therefore, it is preferable to use an organic film (thickness: 2 to 3 μm) such as an acrylic resin for the second interlayer insulating film. Further, in order to form a contact hole in the TFT 500 and to take out an electrode in the peripheral region, the second interlayer insulating film 518 is required to have a patterning performance, and usually a photosensitive organic film is often used.

  On the other hand, in a display device having a TFT having the above-described structure in the display region, when an optical sensor for detecting the brightness of external light is to be monolithically formed in the peripheral region of the display device, the manufacturing process is increased. If it tries to suppress to the minimum, the element structure of an optical sensor will be limited.

  FIG. 16 is a schematic cross-sectional view showing a cross-section of the element structure of the optical sensor 400 that satisfies these conditions. A semiconductor film 411 that forms an optical sensor is formed over a glass substrate 410, and a doping region (p region 411c or n region 411b) of the semiconductor film 411 is formed in a vertical direction with respect to a non-doping region (i region 411a) ( It is formed not in the stacking direction) but in the lateral direction (plane direction). In general, a structure having a PIN junction in a lateral direction (plane direction) parallel to the formation surface is called a lateral type PIN photodiode.

  Each member constituting the optical sensor 400 is formed by the same process as each member constituting the TFT of FIG. For example, an insulating film 412 formed of the same material and the same process as the gate insulating film 512 is formed on the upper layer of the semiconductor film 411, and the same material and the same as that of the source electrode 517 are formed on the upper layer of the first interlayer insulating film 414. A p-side electrode 417 formed by the process and an n-side electrode 415 formed by the same material and the same process as the drain electrode 515 are formed.

  Furthermore, a surface protective film 418 formed by the same material and the same process as the second interlayer insulating film 518 is formed thereon. In this case, in the pixel arrangement region (display region), the second interlayer insulating film 518 electrically insulates the interlayer between the TFT 500 formation layer and the pixel electrode 519 formation layer, and improves the flatness of the formation surface of the pixel electrode 519. In the peripheral region (frame region) outside the pixel array region (outside the display region), the optical sensor 400 and the electrodes connected to the optical sensor 400 are protected from the outside air as the surface protective film 418 of the active matrix substrate. Play a role. Thus, it is desirable that the surface protective film 418 is formed by the same process as the second interlayer insulating film 518 and is formed on substantially the entire surface from the display region to the peripheral region.

  Such an optical sensor 400 shown in FIG. 16 can be used in place of the optical sensor (discrete component provided in the peripheral area) of the conventional display device shown in FIG. 13, and shown in FIG. When incorporating a display device into an electronic device, it is possible to reduce the number of components and the component mounting process.

In Patent Document 5, as another example of the structure of the optical sensor 400, a TFT having a bottom gate structure (reverse stagger structure) using an amorphous Si film and a MIS (Metal-Insulator-Semiconductor) type junction are provided. A photodiode formed monolithically on the same substrate is described.
JP-A-4-174819 (Publication Date; June 23, 1992) JP-A-5-241512 (Publication Date; September 21, 1993) JP 2002-62856 A (publication date; February 28, 2002) JP 2002-175026 A (publication date: June 21, 2002) Japanese Patent Laid-Open No. 6-188400 (Publication Date: July 8, 1994)

  However, it has been clarified that the following problems occur when an optical sensor shown in FIG. 16 is formed in a peripheral region on an active matrix substrate to realize a display device.

  As shown in FIG. 14, the active matrix substrate constituting the display device is roughly divided into a display area (H) and a peripheral area (frame area) (S). The latter peripheral area (S) is further divided into a housing. It is divided into a light shielding region (S1) shielded by the body and a non-light shielding region (S2) that is located in an opening (for example, corresponding to the opening 916 in FIG. 14) provided in the housing and receives external light. be able to. Since the above-described optical sensor needs to receive external light, it is naturally necessary to be disposed in the non-shielding region (S2) on the active matrix substrate.

  As described above, the second interlayer insulating film is formed on the substantially entire surface from the display region to the peripheral region. However, external light reaching the second interlayer insulating film (assuming use under outdoor sunlight) Considering how the) reaches the second interlayer insulating film, it is as follows.

  Display area (H): Since a part of external light is absorbed by a polarizing plate (not shown) and a color filter provided on the counter substrate, external light reaching the second interlayer insulating film on the active matrix substrate Is limited to light in a specific wavelength region. In particular, since almost 100% of ultraviolet rays are absorbed by the polarizing plate and the color filter, no ultraviolet rays reach the second interlayer insulating film.

  Light shielding area (S1): All external light is shielded by the housing. Of course, no ultraviolet rays reach the second interlayer insulating film on the active matrix substrate.

  Non-shielding region (S2): Since external light is directly incident, light of all wavelengths (including ultraviolet rays) included in the external light reaches the second interlayer insulating film on the active matrix substrate.

  That is, considering the case where the display device is used outdoors, ultraviolet rays contained in sunlight can reach the second interlayer insulating film on the active matrix substrate only in the non-light-shielding region (S2) in the peripheral region. Become.

  As described above, the second interlayer insulating film is formed of an organic film having photosensitivity such as an acrylic resin, but the organic film used here has not been considered for resistance to ultraviolet rays. Therefore, when the light resistance test of the second interlayer insulating film located in the non-light-shielding region (S2) is carried out, the phenomenon that the film deteriorates due to the ultraviolet irradiation for a long period of time, that is, the initially transparent film turns brownish or clouded. It became clear that the phenomenon to become. Further, as a result, it has been found that the transparency of the second interlayer insulating film is impaired, the external light reaching the optical sensor located thereunder is reduced, and the sensitivity of the optical sensor is deteriorated and the characteristics are changed over time. . This phenomenon is a problem related to the reliability of a display device including an optical sensor, and needs to be solved.

  Even when another environmental sensor (such as a temperature sensor or a humidity sensor) is used instead of the optical sensor, if the film quality of the second interlayer insulating film deteriorates, the reliability of the environmental sensor existing thereunder is impaired. Therefore, it is necessary to try to solve it.

  As a method for solving such a problem, it is effective to increase the ultraviolet resistance of the second interlayer insulating film. However, further improvement of the resin material of the existing second interlayer insulating film that is already optimized for other required specifications such as large area coating performance, patternability, flatness, heat resistance to process temperature, etc. There is concern about the performance trade-off. Therefore, there is a demand for a countermeasure by another method on the premise that the current second interlayer insulating film is used.

  Accordingly, the present invention provides an active matrix substrate and a display device having an environmental sensor (for example, an optical sensor) formed in a peripheral region of the active matrix substrate, while forming a surface protective film above the arrangement layer of the environmental sensor. It is another object of the present invention to provide an active matrix substrate and a display device that can prevent poor sensitivity of environmental sensors and deterioration of characteristics over time due to alteration of the surface protective film.

  The active matrix substrate of the present invention is an active matrix substrate having a pixel array region in which a plurality of pixels are arrayed and a peripheral region other than the pixel array region on the same substrate. A plurality of active elements provided corresponding to each of the plurality of pixels and switching each pixel, an interlayer insulating film provided above the plurality of active elements, and a plurality of layers formed above the interlayer insulating film In the peripheral region, an environmental sensor and a surface protective film provided above the environmental sensor arrangement layer are disposed, and the surface protective film is An opening is provided in a portion corresponding to the position above the environmental sensor arrangement position.

  Further, the display device of the present invention includes the active matrix substrate, a counter substrate disposed so as to face the surface of the active matrix substrate on which the active element is formed, the active matrix substrate, and the counter substrate. And a display medium disposed in the gap.

  The active matrix substrate of the present invention is provided with an opening in a portion corresponding to the upper part of the environmental sensor arrangement position of the surface protective film arranged in the upper layer of the environmental sensor, so that the surface protection is performed by ultraviolet rays contained in external light. The phenomenon that the film is altered can be avoided. As a result, it is possible to realize an environmental sensor with good sensitivity and small change in characteristics over time, and an active matrix substrate and a display device with excellent reliability can be realized.

[Embodiment 1]
Hereinafter, with reference to the drawings, an outline of a display device according to Embodiment 1 of the present invention and an active matrix substrate used in the display device will be described taking a liquid crystal display device as an example.

  FIG. 1 is an overall configuration diagram of a display device 1 according to the present invention. FIG. 2 is a cross-sectional view showing a state in which the display device 1 is incorporated in a housing. The display device 1 includes an active matrix substrate 2 in which a large number of pixels 5 are arranged in a matrix, and a counter substrate 3 disposed so as to face the active matrix substrate 2. A certain liquid crystal is sandwiched. The active matrix substrate 2 and the counter substrate 3 are bonded together by a frame-shaped seal resin 25 along the outer periphery of the counter substrate 3.

  Each pixel 5 of the active matrix substrate 2 is provided with a thin film transistor (TFT) 6 and a pixel electrode 7 for driving the display medium 4, and the counter substrate 3 is provided with a counter electrode (not shown) and a color filter. (Not shown) is formed.

  The active matrix substrate 2 has an area (pixel arrangement area) 8 in which the pixels 5 are arranged and a peripheral area 9 close to the pixel arrangement area, and the counter substrate 3 covers the pixel arrangement area 8 and the peripheral area. It arrange | positions so that a part of 9 may be exposed.

  Further, in the peripheral region 9 of the active matrix substrate 2, an FPC (Flexible Printed Circuit) 10 for connecting an external drive circuit 30 to the display device 1 is mounted on a terminal 38, and is an example of an environmental sensor. An optical sensor 11 is provided for detecting the brightness of outside light. In addition, peripheral circuits (a driving circuit (not shown) for driving the TFTs 6 in the pixel array region 8 based on an input signal from an external driving circuit), wirings connected to the optical sensor 11 and the driving circuit (36 ), A lead-out wiring (not shown) from the pixel array region 8 is also provided.

  The TFT 6 formed in the pixel array region 8 and the optical sensor 11 formed in the peripheral region 9 are monolithically formed on the same substrate by the same process.

  The display device 1 shown in FIG. 1 is incorporated into a casing 35 with an opening as shown in FIG. The opening 37 of the housing 35 is disposed so as to face the position where the optical sensor 11 is disposed, and external light reaches the optical sensor 11 through the opening 37.

  The display device 1 uses a transmissive mode that uses transmitted light as its display mode. Therefore, the backlight 12 is provided on the side (back side) of the active matrix substrate 2 in the housing 35 opposite to the counter substrate arrangement side. Note that the backlight 12 is not necessary when a reflective display mode using reflection of external light is used as the display mode, or when a self-luminous element such as an EL is used as the display medium.

  In addition, since the above-described optical sensor 11 is intended to detect external light, when the light from the backlight 12 enters the optical sensor 11, there arises a problem that the optical sensor 11 malfunctions. Therefore, the backlight 12 is not disposed below the portion where the photosensors 11 are disposed on the active matrix substrate 2 (the side opposite to the side where the photosensors 11 are disposed on the active matrix substrate 2), or the active matrix substrate 2 It is necessary to consider that the light from the backlight 12 does not enter the optical sensor 11 by providing a light shielding member (aluminum tape or the like) on the back surface of the optical sensor arrangement portion.

  The display device 1 of the present invention described above can be applied to a display system with an automatic light control function that detects the illuminance of external light using the optical sensor 11 and automatically controls the display luminance in accordance with the detected illuminance. That is, a control circuit for controlling the luminance of the backlight 12 or the luminance signal of the display signal based on the brightness information of the external light output from the optical sensor 11 provided in the peripheral region 9 of the active matrix substrate 2 is provided. Thus, the display brightness of the display device 1 can be automatically controlled.

  The control circuit may be formed integrally with the display device 1 or may be formed separately from the display device 1. Examples of the case where the display device 1 is integrally formed include a case where the active matrix substrate 2 is monolithically formed, or a control circuit is formed separately from the active matrix substrate 2 to form a COG (Chip On Grass) system. The case where it mounts on the active matrix substrate 2 by the above etc. is mentioned. Further, as an example in which the display device 1 is separately formed, a control circuit is formed separately from the active matrix substrate 2 and connected to the active matrix substrate 2 via an FPC or the like, or the display device 1 There is a case where a control circuit is arranged in an electronic device including the above and a signal is transmitted from the control circuit to the active matrix substrate 2.

  This control circuit is used to automatically adjust the brightness (dimming) so that the display brightness is increased in bright environments such as outdoors, and the display brightness is decreased in relatively dark environments such as at night or indoors. Thus, low power consumption and long life of the display device can be realized.

  Next, the detailed structure of the display device 1 of the present invention will be described with reference to FIG. 3, FIG. 4, and FIG. FIG. 3 is a schematic cross-sectional view schematically showing a cross-sectional structure of the pixel array region (display region) 8 per pixel 5 in the display device 1 of FIG. A display medium (liquid crystal in the present embodiment) 4 is sandwiched between the active matrix substrate 2 and the counter substrate 3. A thin film transistor (TFT) 6 and a pixel electrode 7 for driving the liquid crystal 4 are formed on the active matrix substrate 2.

  Hereinafter, the structure of the TFT 6 using the polycrystalline Si film used in this embodiment and the pixel 5 including the TFT 6 will be described with reference to FIGS. 1 and 3. The structure of the TFT 6 used here is called a “top gate structure” or “positive stagger structure”, and includes a gate electrode 16 on the upper layer of a semiconductor film (polycrystalline Si film) 13 to be a channel. In addition, when laminating | stacking a some layer with respect to a board | substrate in this way, the board | substrate side is described as the lower side, and the direction where the distance from a board | substrate to a layer leaves is described as the upper side.

  As the substrate 14 serving as the base substrate, a glass substrate can be mainly used. For example, non-alkali barium borosilicate glass or alumino borosilicate glass is used. The TFT 6 includes a polycrystalline Si film 13 formed on the substrate 14, a gate insulating film 15 formed so as to cover the polycrystalline Si film 13 (for example, a silicon oxide film or a silicon nitride film can be used), A gate electrode 16 formed on the gate insulating film 15 (for example, Al, Mo, Ti, or an alloy thereof can be used), and a first interlayer insulating film 17 formed to cover the gate electrode 16 (for example, A silicon oxide film or a silicon nitride film can be used).

  Here, the region of the semiconductor film facing the gate electrode 16 through the gate insulating film 15 functions as the channel region 13 (a). In addition, the region other than the channel region of the semiconductor film is an n + layer doped with impurities at a high concentration, and functions as a source region 13 (b) and a drain region 13 (c). Although not shown here, LDD (Lightly Doped Drain) regions doped with impurities at a low concentration are formed on the channel region side of the source region and the channel region side of the drain region in order to prevent deterioration of electrical characteristics due to hot carriers. Is formed.

  Note that a base coat film (for example, a silicon oxide film or a silicon nitride film can be used) may be provided on the surface of the glass substrate (under the polycrystalline Si film 13). The polycrystalline Si film 13 can be obtained by crystallizing a semiconductor film (non-crystalline Si film) having an amorphous structure by heat treatment such as laser annealing or RTA (Rapid Thermal Annealing).

  A source electrode 18 (for example, Al, Mo, Ti, or an alloy thereof can be used) is formed on the first interlayer insulating film 17, and a contact hole that penetrates the first interlayer insulating film 17 and the gate insulating film 15. Is electrically connected to the source region 13 (b) of the semiconductor film. Similarly, the drain electrode 19 (for example, Al, Mo, Ti, or an alloy thereof can be used) formed on the first interlayer insulating film 17 penetrates the first interlayer insulating film 17 and the gate insulating film 15. It is electrically connected to the drain region 13 (c) of the semiconductor film through the contact hole.

  The above is the basic structure of the TFT 6 used here. In the pixel array region (display region) 8, a second interlayer insulating film 20 is further formed so as to cover the TFT 6 described above. Here, since the second interlayer insulating film 20 is required to flatten the unevenness of the lower layer in addition to the insulation between the layers, an organic film that can be formed by coating or printing is mainly used.

  Further, a pixel electrode 7 (for example, ITO (Indium-Tin-Oxide), IZO (Indium-Zinc-Oxide), Al, etc. can be used) is formed on the second interlayer insulating film 20. The pixel electrode 7 is electrically connected to the drain electrode 19 through a contact hole formed in the second interlayer insulating film 20. As the second interlayer insulating film 20, a photosensitive organic insulating film is preferably used, whereby a contact hole can be easily formed in the second interlayer insulating film by mask exposure and development processing. . Examples of such an organic insulating film having photosensitivity include acrylic, polyimide, BCB (Benzo-Cyclo-Butene), and the like.

  4 is a schematic cross-sectional view of the peripheral region 9 in the display device 1 of FIG. 1, and FIG. 5A is a cross-sectional structure diagram of the optical sensor 11 formed in the peripheral region 9.

  Hereinafter, the structure of the optical sensor 11 will be described with reference to FIGS. 4 and 5A. The structure of the optical sensor 11 used here is called a “lateral structure photodiode”, and includes a diode in which a semiconductor PIN junction is formed in the surface direction (lateral direction) of the substrate.

  A PIN diode made of a polycrystalline Si film 21 is formed on a glass substrate 14 (substrate common to the substrate on which the TFT is formed) serving as a base material. The film thickness of the polycrystalline Si film 21 of the PIN diode and the film thickness of the polycrystalline Si film 13 of the TFT 6 in the pixel array region 8 (display region) are the same. The PIN junction is formed by a p + layer and an n + layer that are highly doped with impurities, and an i layer that is not doped with impurities. Instead of the i layer, it is also possible to use a p-layer or an n-layer doped at a low concentration alone or in combination.

  Further, a gate insulating film 15 (for example, a silicon oxide film or a silicon nitride film can be used) common to the constituent members of the pixel array region 8 and the first interlayer insulation so as to cover the polycrystalline Si film 21 having the PIN junction. A film 17 (for example, a silicon oxide film or a silicon nitride film can be used) is formed. A p-side electrode 33 (for example, Al, Mo, Ti, or an alloy thereof can be used) formed on the first interlayer insulating film 17 is a contact hole that penetrates the first interlayer insulating film 17 and the gate insulating film 15. Is electrically connected to the p + region of the semiconductor film. Similarly, the n-side electrode 34 (for example, Al, Mo, Ti, or an alloy thereof can be used) formed on the first interlayer insulating film 17 includes the first interlayer insulating film 17 and the gate insulating film 15. It is electrically connected to the n + region of the semiconductor film through a penetrating contact hole.

  The above is the basic structure of the optical sensor 11. As described above, the constituent members of the optical sensor 11 are basically the same as the constituent members of the TFT 6 in the pixel array region described above. Therefore, both manufacturing processes can be made common. In this way, the TFT 6 in the pixel array region 8 and the photosensor 11 in the peripheral region 9 are monolithically formed on the active matrix substrate 2.

  In addition to the photosensor 11, the peripheral region 9 includes a peripheral circuit (a drive circuit (not shown) for driving the TFT 6 in the pixel array region 8 based on an input signal from an external drive circuit), a light A wiring 36 connected to the sensor 11 and the driving circuit, a lead-out wiring (not shown) from the pixel array region 8 and the like are also formed. For the purpose of protecting these, the second interlayer insulating film 20 (acrylic, polyimide, common to the constituent members of the pixel array region 8 is formed on the upper layer so as to cover the optical sensor 11, the drive circuit, and various wirings in the peripheral region. , An organic insulating film such as BCB).

  The second interlayer insulating film 20 serves as a surface protective film in the peripheral region 9. However, the second interlayer insulating film 20 is intentionally formed with an opening 22 that is a feature of the present embodiment above the optical sensor 11. The opening 22 can be formed at the same time when a contact hole is formed in the second interlayer insulating film 20 in the pixel array region 8. That is, the second interlayer insulating film 20 functions as an interlayer insulating film in the pixel array region 8 and functions as a surface protective film in the peripheral region 9.

  That is, the structural features of the display device 1 according to the present embodiment are that the active matrix substrate 2 includes the pixel array region 8 (display region) and the peripheral region 9, and the brightness of external light is detected in the peripheral region. The optical sensor 11 is formed, the second interlayer insulating film 20 used in the pixel array region 8 is also formed in the peripheral region, and the optical sensor 11 of the second interlayer insulating film (surface protective film) 20. It has the point which has an opening part in the part corresponded above.

  As a result, even if the external light includes ultraviolet rays, the optical sensor 11 does not have the second interlayer insulating film 20 above the optical sensor 11, and thus the discoloration of the second interlayer insulating film 20 caused by the ultraviolet rays is caused. Not affected. Accordingly, it is possible to accurately detect a change in the brightness of external light stably over a long period of time. Conventionally, it has been necessary to design the optical sensor 11 with excessive specifications in anticipation of deterioration of the second interlayer insulating film 20 due to ultraviolet rays (decrease in transmittance). There is no need to worry about a decrease in the transmittance of the insulating film 20, and the optical sensor 11 can be optimally designed. For this reason, it becomes possible to make optical sensor 11 itself smaller than before. As a result, the peripheral region 9 in which the optical sensor 11 is arranged can be reduced to a minimum, and it is possible to contribute to a narrow frame of the display device.

  In the above-described embodiment, an example is described in which the second interlayer insulating film formed in the pixel array region 8 and the surface protective film formed in the peripheral region 9 are formed by the same material and the same process. However, it is not limited to this. Even if both are formed by different materials or different processes, if the surface protection film is not sufficiently resistant to ultraviolet rays, the above structure (structure in which the opening 22 is provided in the surface protection film) is used to implement the present invention. It is possible to obtain the effects of the invention. In particular, when the surface protective film has photosensitivity, it is effective in that the opening 22 can be easily formed by photolithography.

  By the way, as described above, when the opening 22 is formed in the second interlayer insulating film 20 above the photosensor 11, the p-side electrode 33 and the n-side electrode 34 made of metal are exposed. Therefore, when there is a concern about oxidation or corrosion due to the contact of both electrodes with the outside air, it is preferable to form a protective member 42 on both electrodes as shown in FIG. As the protective member 42, an oxide film that is stable against the outside air (oxygen, moisture) and excellent in resistance to ultraviolet rays is suitable. For example, the same conductive oxide film as the pixel electrode 7 (for example, ITO, IZO, etc.) Can be used. In addition, it is preferable to form the protective member 42 by the same process as that for the pixel electrode 7 because no additional process is required. When the protective member 42 having conductivity is provided in the opening 22 as described above, the pattern shape of each electrode is set so that the p-side electrode 33 and the n-side electrode 34 are not short-circuited via the protective member 42. Accordingly, the protection member 42 needs to be patterned.

[Embodiment 2]
As a second embodiment of the present invention, a description will be given of an optical sensor 11 provided with a protective member other than a conductive oxide film. Since the optical sensor 11 is the same as that described in the first embodiment except that the protective member 24 is provided without using the protective member 42, the same components are denoted by the same reference numerals. Therefore, the description is omitted.

  FIG. 6A is a cross-sectional structure diagram in the case where a protective member 24 is added to the optical sensor 11 described above. That is, the protective member 24 is provided in the opening 22 formed in the second interlayer insulating film 20 on the optical sensor 11. As a result, it is possible to protect the upper surface of the photosensor 11 exposed in the peripheral region 9, and it is possible to ensure high reliability against not only ultraviolet rays but also outside air.

  The protective member 24 used here only needs to have transparency with respect to the wavelength range of light received by the optical sensor 11 and resistance to ultraviolet rays, and, like the second interlayer insulating film 20, has a large area coating performance and patterning property. Strict specifications such as flatness and heat resistance against process temperature are not required. Therefore, a wide range of materials can be applied as the protective member 24. For example, a material such as a fluorine-based resin, a silicone resin, an epoxy resin, or an acrylic resin can be used. Specifically, silicone potting materials manufactured by Toray Dow Corning (for example, SE1880), Aflex (registered trademark), Cytop (registered trademark) manufactured by Asahi Glass Co., Ltd., and the like can be used. In order to keep the transmittance high, it is preferable to employ a resin that does not contain a filler that causes light scattering. In consideration of simplification of the process of forming the protective member, it is preferable to employ a room temperature curable resin (such as a room temperature curable silicone resin) that does not require a curing oven.

  6A shows a form in which the protective member 24 covers the entire opening 22 of the second interlayer insulating film 20, but this is not particularly necessary, as shown in FIG. 6B. For example, when the opening 22 is wider than the size of the optical sensor 11, the protective member 24 is disposed in a part of the opening 22 so as to cover at least the optical sensor 11 instead of covering the entire opening. Also good. Further, as shown in FIG. 6C, for example, the protective member 24 may be disposed in a part of the opening 22 so as to cover at least a position where light enters the optical sensor 11. Further, when there is concern about oxidation or corrosion of the electrodes exposed in the opening 22 (p-side electrode 33 and n-side electrode 34), at least a part of the opening 22 covers the protective member so as to cover both electrodes. 24 may be arranged. Further, the protective member 42 described in FIG. 5B of the first embodiment can be used in combination with the protective member 24.

  FIG. 7 is a schematic cross-sectional view of the peripheral region 9 when the protective member 24 is added on the optical sensor 11. As shown in FIG. 7, the height X of the protective member 24 in the normal direction of the TFT formation surface of the active matrix substrate 2 (the direction of the arrow in FIG. 7) is the thickness of the counter substrate 3 and the display medium 4. It is desirable that the total Y is not more than Thereby, when the display device 1 is incorporated in the housing, it becomes easy to secure a clearance between the protective member 24 and the housing.

[Embodiment 3]
FIG. 8 is a schematic plan view of the display device 26 according to the third embodiment and a cross-sectional view taken along line A1-A2. In addition, about the structure which is not demonstrated, it is the same as the display apparatus of Embodiment 2. FIG.

  The seal resin 25 is formed along substantially the outer periphery of the counter substrate 3, and an opening is formed in a part of the side facing the peripheral region 9 of the active matrix substrate 2. This opening is an injection port 27 for injecting liquid crystal as the display medium 4 into the gap between the active matrix substrate 2 and the counter substrate 3. After injecting liquid crystal from the injection port 27, the liquid crystal is sealed between the active matrix substrate 2 and the counter substrate 3 by sealing with a resin sealing member 28.

  Here, in the display device 26 according to the third embodiment, the optical sensor 11 is arranged in the vicinity of the injection port 27 for injecting liquid crystal (preferably within a distance of 5 mm). Further, the sealing member 28 of the injection port 27 for injecting liquid crystal has a structure that also serves as the protective member 24 of the optical sensor 11.

  Thus, since the sealing member 28 of the injection port 27 and the protective member 24 of the optical sensor 11 are made of the same material, it is possible to work in the same process as compared with the case of using different materials. In addition, the protective member arranging step of the optical sensor 11 and the sealing member arranging step of the injection port 27 are combined to form the sealing member 28 and the protective member 24 integrally, thereby preventing an increase in man-hours. be able to.

[Embodiment 4]
FIG. 9 is a schematic plan view of a display device 40 according to the fourth embodiment and a cross-sectional view taken along the line BB ′. In addition, about the structure which is not demonstrated, it is the same as the display apparatus of Embodiment 2. FIG.

  Here, in the display device 40, the FPC 10 is mounted in the peripheral region, and the connection of the FPC 10 is reinforced around the mounting portion of the FPC 10 (mechanical reinforcement or reliability enhancement of the mounting portion by moisture / dust prevention). A reinforcing member 39 (reinforcing resin) is provided.

  The optical sensor 11 is disposed in the vicinity of the mounting portion of the FPC 10, and the reinforcing member 39 has a structure in which the protective member 24 of the optical sensor 11 is integrally formed.

  Thus, since the reinforcing member 39 of the FPC 10 and the protective member 24 of the optical sensor 11 are made of the same material, it is possible to work in the same process as compared with the case of using different materials. Moreover, the increase in a man-hour can be prevented by carrying out combining the protection member arrangement | positioning process of the optical sensor 11, and the reinforcement member arrangement | positioning process of FPC10.

  Of course, even when a TCP (Tape Carrier Package) or LSI is mounted in the peripheral area 9 instead of the FPC 10, the reinforcing member 39 that reinforces these circuit members and the protective member 24 of the optical sensor 11 are integrated. By forming, the same effect can be obtained.

[Embodiment 5]
FIG. 10 is an overall configuration diagram of the display device 29 according to the fifth embodiment. FIG. 11 is a schematic cross-sectional view of a portion of the peripheral region 9 where the optical sensor 11 is disposed. In the fifth embodiment, the counter substrate 3 is large enough to cover the photosensor 11 in the peripheral region 9, and the protective member 24 of the photosensor 11 is formed between the active matrix substrate 2 and the counter substrate 3. It has a structure that exists in the gap. In addition, the same code | symbol is attached | subjected to the structure same as Embodiment 1 to Embodiment 4, and description is abbreviate | omitted.

  Usually, when a resin material with low hardness is used for the protective member 24, the mechanical strength of the protective member, such as the occurrence of surface scratches, may be a problem, but the protective member 24 is covered with the counter substrate 3, It is possible to perform mechanical (physical) protection of the protection member 24.

  At this time, it is desirable not to form a polarizing plate or a color filter in the portion covering the peripheral region 9 of the counter substrate 3 so as not to prevent the outside light from entering the optical sensor 11. Further, it is necessary to consider that the backlight system 12 is not located directly below the optical sensor 11.

  Furthermore, as shown in FIG. 12, when the gap between the optical sensor 11 and the counter substrate 3 is completely filled with the protective member 24, the protective member 24 of the optical sensor 11 does not touch outside air except for the side surface. This can be realized and the influence of the humidity of the outside air can be further reduced. In addition, since an air layer having a low refractive index is not interposed between the optical sensor 11 and the counter substrate 3, light reflection loss at the interface between the air layer and the protective member 24 is reduced, and the S / N of the optical sensor 11 is improved. It is also possible to make it.

  In the above-described first to fifth embodiments, an example in which the TFT 6 and the optical sensor 11 are formed using a polycrystalline Si film has been described. However, it is also possible to form both with an amorphous Si film. In addition, a TFT having a bottom gate structure (reverse stagger structure) may be used instead of a TFT having a top gate structure (forward stagger structure). In addition, other active elements such as MIM (Metal-Insulator-Metal) can be used instead of the TFT 6.

  Further, the optical sensor can use not only a PIN junction but also a photodiode having a Schottky junction or a MIS type junction. For example, as an example in which a TFT having a bottom gate structure (inverted stagger structure) using an amorphous Si film and a photodiode having a MIS type junction are formed monolithically on the same substrate, Patent Document 5 may be referred to.

  In the first to fifth embodiments, the display device in which the optical sensor is formed in the peripheral region 9 as a representative of the environmental sensor has been described. However, a temperature sensor, a humidity sensor, and a backlight color sensor are used instead of the optical sensor. Even when various sensors such as a brightness sensor are formed, by adopting the configuration of the present application, it is possible to reduce deterioration of sensor characteristics due to deterioration of a surface protective film above the sensor.

  The present invention can be widely applied to flat panel display devices including active elements, and can be applied to various display devices such as EL display devices and electrophoretic display devices in addition to liquid crystal display devices. As a result, the present invention can also be used for electronic devices that use display devices (for example, mobile phones, PDAs, DVD players, mobile game devices, notebook PCs, PC monitors, television receivers, etc.).

1 is an overall configuration diagram showing an outline of a display device according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view illustrating a state where the display device according to Embodiment 1 is incorporated in a housing. 4 is a schematic cross-sectional view illustrating a pixel structure of a pixel array region (display region) of the display device according to Embodiment 1. FIG. 3 is a schematic cross-sectional view of a peripheral region of the display device according to Embodiment 1. FIG. (A) is a cross-sectional schematic diagram which shows the structure of the optical sensor which concerns on Embodiment 1. FIG. (B) is a cross-sectional schematic diagram which shows the modification of the structure of the optical sensor which concerns on Embodiment 1. FIG. (A) is a cross-sectional schematic diagram which shows the outline of the display apparatus which concerns on Embodiment 2. FIG. (B) is a cross-sectional schematic diagram which shows the modification of the display apparatus which concerns on Embodiment 2. FIG. (C) is a cross-sectional schematic diagram which shows the modification of the display apparatus which concerns on Embodiment 2. FIG. 6 is a schematic cross-sectional view of a peripheral region of a display device according to Embodiment 2. FIG. It is the schematic plan view of the display apparatus which concerns on Embodiment 3, and sectional drawing in the A1-A2 line. It is the schematic plan view of the display apparatus which concerns on Embodiment 4, and sectional drawing in the B1-B2 line | wire. FIG. 10 is an overall configuration diagram illustrating an outline of a peripheral region of a display device according to a fifth embodiment. FIG. 10 is a schematic cross-sectional view (modification example) of a peripheral region of a display device according to Embodiment 5. FIG. 10 is a schematic cross-sectional view (modification example) of a peripheral region of a display device according to Embodiment 5. It is a whole block diagram of the conventional liquid crystal display device. It is a cross-sectional schematic diagram of the optical sensor mounting part of the conventional liquid crystal display device. It is a cross-sectional schematic diagram of a conventional TFT formed in a pixel array region of an active matrix substrate. It is a cross-sectional schematic diagram of a conventional photosensor formed in a peripheral region of an active matrix substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Active matrix substrate 3 Opposite substrate 4 Display medium 5 Pixel 6 Active element (TFT)
7 Pixel electrode 8 Pixel array area (display area)
9 Peripheral area 10 FPC
11 Environmental sensor (light sensor)
12 Backlight 13 Polycrystalline Si film (semiconductor film)
14 Substrate 15 Gate insulating film 16 Gate electrode 17 First interlayer insulating film 18 Source electrode 19 Drain electrode 20 Second interlayer insulating film, surface protective film 21 Polycrystalline Si film (semiconductor film)
22 Opening 31 Color filter 32 Counter electrode (common electrode)
33 p-side electrode 34 n-side electrode 41 glass substrate

Claims (19)

In an active matrix substrate having a pixel array region in which a plurality of pixels are arrayed and a peripheral region other than the pixel array region on the same substrate,
In the pixel array region, an active element provided corresponding to each of the plurality of pixels, an interlayer insulating film provided above the active element, and an upper layer above the interlayer insulating film are provided. A plurality of formed pixel electrodes are disposed;
In the peripheral region, an environmental sensor and a surface protective film provided in a layer above the arrangement layer of the environmental sensor are arranged,
The active matrix substrate, wherein the surface protective film has an opening in a portion corresponding to the position above the environmental sensor placement position.   The active matrix substrate according to claim 1, wherein the interlayer insulating film and the surface protective film are formed of the same material.   The active matrix substrate according to claim 1, wherein the surface protective film is made of a photosensitive material.   The active matrix substrate according to any one of claims 1 to 3, further comprising a protective member so as to cover at least a part of the opening of the surface protective film.   The active matrix substrate according to claim 4, wherein the protective member is made of a material that is more resistant to ultraviolet rays than the surface protective film.   A metal electrode connected to the environmental sensor is disposed in the opening of the surface protective film, and the protective member is formed of the same material as the pixel electrode on the metal electrode. The active matrix substrate according to claim 4.   7. The active element and the environmental sensor are formed by the same process, and the interlayer insulating film and the surface protective film are formed by the same process. The active matrix substrate according to one item.   The active matrix substrate according to claim 7, wherein the active element is a thin film transistor, and the environmental sensor is a photodiode having a lateral structure.   The active matrix substrate according to any one of claims 1 to 8, a counter substrate disposed so as to face a surface of the active matrix substrate on which the active element is formed, and the active matrix substrate; And a display medium disposed in a gap between the counter substrates. 6. The active matrix substrate according to claim 4 or 5, a counter substrate disposed so as to face a surface of the active matrix substrate on which the active element is formed, the active matrix substrate, and the counter substrate A display medium disposed in the gap of
The display is characterized in that the counter substrate is arranged so as to cover the entire area of the pixel array area and to expose at least the area where the environmental sensor is formed in the peripheral area. apparatus.   The display device according to claim 10, wherein a height of the protection member in a normal direction of the active element formation surface is equal to or less than a total thickness of the counter substrate and the display medium. 6. The active matrix substrate according to claim 4 or 5, a counter substrate disposed so as to face a surface of the active matrix substrate on which the active element is formed, the active matrix substrate, and the counter substrate A display medium disposed in the gap of
The display device, wherein the counter substrate is disposed so as to cover the entire region of the pixel arrangement region and to cover at least the region where the environmental sensor is formed in the peripheral region. .   The display device according to claim 12, wherein the protective member is disposed in a gap between the active matrix substrate and the counter substrate. 6. The active matrix substrate according to claim 4 or 5, a counter substrate disposed so as to face a surface of the active matrix substrate on which the active element is formed, the active matrix substrate, and the counter substrate A display medium disposed in the gap of
A sealing member for sealing the injection port for injecting the display medium and the injection port is provided,
The display device, wherein the protection member and the sealing member are made of the same material.   The display device according to claim 14, wherein the injection port is located in the vicinity of the optical sensor, and the sealing member and the protection member are integrally formed. 6. The active matrix substrate according to claim 4 or 5, a counter substrate disposed so as to face a surface of the active matrix substrate on which the active element is formed, the active matrix substrate, and the counter substrate A display medium disposed in the gap of
A display device, wherein a circuit member is mounted in a peripheral region of the active matrix substrate, and a reinforcing member made of the same material as the protective member is disposed in a mounting portion of the circuit member.   The display device according to claim 16, wherein the reinforcing member and the protective member are integrally formed.   The environment sensor is an optical sensor, and includes a control circuit that automatically controls display luminance based on brightness information of external light detected by the optical sensor. The display apparatus in any one. An electronic apparatus comprising the display device according to any one of claims 9 to 18.

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