JP4623046B2 - Electro-optical device and electronic apparatus - Google Patents

Description

The present invention relates to an electro-optical device, a light receiving device, and an electronic apparatus suitable for a display device for controlling display luminance.

The liquid crystal panel is configured by sealing liquid crystal between two substrates such as a glass substrate and a quartz substrate.
Each substrate is provided with an electrode, and an image signal is supplied to the electrode. The optical characteristics of the liquid crystal between the electrodes of each substrate change according to the image signal. That is, by applying a voltage based on the image signal to the liquid crystal between the electrodes of each substrate, the alignment of the liquid crystal molecules is changed. Thereby, the light transmittance in each pixel changes according to the image signal, and the image display according to the image signal is performed.

In order to display with high brightness in such a liquid crystal panel, a backlight is generally provided on the back of the liquid crystal panel. As such a backlight, an apparatus for improving the uniformity of illumination using a light guide plate has been developed. By illuminating the display area of the liquid crystal panel with the backlight, the display on the display area can be observed with sufficient luminance.

By the way, the visibility of the display on the liquid crystal panel changes according to the ambient brightness. For example, the brighter the ambient light, the easier it is to see the display when the illumination in the display area is brighter. Conversely, when the ambient light is sufficiently dark, it is not necessary to make the display area brighter than necessary.

Patent Document 1 discloses a technique for detecting ambient light and controlling the brightness of a backlight based on feedback information in order to provide an easy-to-see display regardless of ambient brightness.

JP 2003-78838 A

By the way, in the apparatus of patent document 1, as an optical sensor which detects ambient light (external light),
Discrete parts are used. For this reason, it is necessary to mount an optical sensor on a flexible printed circuit board, resulting in an increase in man-hours and costs.

Therefore, it is conceivable to form an optical sensor using a PIN diode on a substrate constituting a display panel such as a liquid crystal panel. In this case, P is formed in the same layer as the semiconductor layer in the display area.
An IN type diode is formed.

However, for the semiconductor layer in the display region, it is necessary to form a gate electrode on the semiconductor layer in order to form an LDD structure in a self-aligned manner. Also in the PIN diode formation region, in order to prevent the impurity from being injected into the intrinsic layer, a mask made of a conductive material (hereinafter referred to as a mask conductive layer) is formed on the intrinsic layer in the same layer as the gate electrode. Need to form. In the case where the mask conductive layer remains on the intrinsic layer, the mask conductive layer restricts the incidence of light to the intrinsic layer, so that sufficient photosensitivity cannot be obtained. For this reason, it is necessary to provide a process for removing the masking conductive layer in the PIN diode formation region, which increases the number of processes.

The present invention provides an electro-optical device, a light-receiving device, and an electronic instrument that can obtain sufficient light sensitivity by allowing light to be efficiently incident on an intrinsic layer without removing the conductive layer for a mask. The purpose is to provide.

Electro-optical device according to the present invention, Ri Na and switching elements are formed on the intersections of scanning lines and data lines, a display panel having an element substrate on which external light incident from above, provided under the element substrate In an electro-optical device including an illuminating unit , a light receiving element formed of a PIN diode formed on an element substrate , and provided between the light receiving element and the illuminating unit, and reflects external light transmitted through the element substrate to the light receiving element. a reflecting means for, provided between the reflecting means and the illuminating unit, ing and includes a shielding means for shielding light emitted from the lighting unit. The display panel includes a light shielding region that defines an effective display region, and is configured such that the light shielding region has an opening in the region where the light receiving element is disposed. In addition, a counter substrate is provided to face the element substrate, the element substrate has a region that does not face the counter substrate, and the light receiving element can be formed in a region that does not face the counter substrate. Further, reflection means may have an uneven surface, or the reflecting means may be configured so as to reflect the light receiving element condenses the external light incident. The light receiving element may include a PIN diode having an I-type region, and the I-type region may be masked. Also configured to control the brightness of the illumination unit using the detection result of the light receiving element.

According to such a configuration, most of the light incident from above the element substrate can be incident on the PIN diode, and highly sensitive external light detection is possible.

Further, the electro-optical device according to the present invention is formed on the first and second transparent substrates opposed to each other and the second transparent substrate, and the light incident from the light receiving side surface of the first transparent substrate is the A display panel having a PIN diode that is incident through the light receiving side surface of the second transparent substrate and detects the illuminance of the incident light, and a surface opposite to the light receiving side surface of the second transparent substrate An illuminating unit for irradiating the display panel with light, and a PIN diode provided on the surface side opposite to the light-receiving side surface of the second transparent substrate and passing through the transparent substrate And a reflecting portion that reflects the light.

According to such a configuration, the display panel is constituted by the first and second transparent substrates arranged to face each other, and the PIN diode is formed on the second transparent substrate. The light incident from the light receiving side surface of the first transparent substrate enters the second transparent substrate through the light receiving side surface of the second transparent substrate and is received by the PIN diode. Part of the light incident through the light receiving surface side of the second transparent substrate passes through the second transparent substrate. A reflecting portion is provided on the surface of the second transparent substrate opposite to the light receiving side surface. The light that has passed through the second transparent substrate is reflected by this reflecting portion and enters the PIN diode. Thereby, most of the light incident from the light receiving side surface of the first transparent substrate can be incident on the PIN diode, and high-sensitivity external light detection is possible.

According to another aspect of the present invention, the PIN type diode is characterized in that a masking conductive layer is formed on an intrinsic layer constituting the PIN type diode.

According to such a configuration, during manufacture, the mask conductive layer prevents impurities from being introduced into the intrinsic layer constituting the PIN diode. on the other hand,
At the time of receiving light, the incident light from the light receiving side is hardly incident on the intrinsic layer by the mask conductive layer. Even in this case, since the light that has passed through the second transparent substrate is reflected by the reflecting portion and is incident on the intrinsic layer of the PIN diode, the PIN diode can detect the illuminance of external light with high sensitivity. .

Moreover, according to one aspect of the present invention, the reflection portion is provided in a frame body that holds the illumination portion.

According to such a configuration, the reflecting portion can be provided on the frame body by a relatively simple operation, and highly sensitive external light detection can be performed with a simple configuration.

According to an aspect of the present invention, the reflecting unit includes a light shielding unit that blocks light from the illumination unit, and a reflecting unit that reflects the light that has passed through the second transparent substrate to the PIN diode. It is characterized by comprising.

According to such a configuration, since the light from the illumination unit is shielded by the light shielding means, the PIN
The light from the illumination unit is not incident on the type diode, and the illuminance of external light can be accurately detected by the PIN type diode.

According to an aspect of the present invention, the reflecting portion is provided on a surface opposite to the light receiving side surface of the second transparent substrate.

According to such a configuration, the reflecting portion can be provided on the surface opposite to the light receiving side surface of the second transparent substrate with a relatively simple operation.

According to another aspect of the present invention, the PIN diode is provided in a region where the first and second transparent substrates are opposed to each other.

According to such a configuration, the region where the first and second transparent substrates face each other is a region where display is performed, and external light can enter. Therefore, by disposing the PIN diode in this region, a structure for entering light to the PIN diode can be easily constructed.

According to another aspect of the present invention, the PIN diode is provided in a region where the first and second transparent substrates are not opposed to each other.

According to such a configuration, the region where the first and second transparent substrates face each other is a region where display is performed, and light from the illumination unit enters. Therefore, by providing a PIN diode in a region other than this region, it is possible to prevent light from the illumination unit from entering the PIN diode and to accurately detect illuminance of outside light.

The light-receiving device according to the present invention includes a transparent substrate, a PIN diode formed on the transparent substrate and receiving light incident through the light-receiving side surface of the transparent substrate, and a side opposite to the light-receiving side surface of the transparent substrate And a reflection part that reflects light that has passed through the transparent substrate to the PIN diode.

According to such a configuration, the PIN diode is formed on the transparent substrate and receives light incident through the light receiving side surface of the transparent substrate. Part of the light incident on the transparent substrate passes through the transparent substrate. A reflective portion is provided on the side of the transparent substrate opposite to the light receiving side surface, and light that has passed through the transparent substrate is reflected to the PIN diode side. Thereby, most of the light incident from the light receiving side surface of the transparent substrate can be incident on the PIN diode, and highly sensitive external light detection is possible.

In addition, an electronic apparatus according to the present invention is configured using the electro-optical device.

According to such a configuration, external light can be detected with high sensitivity, and display can be optimized according to the illuminance of external light.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an outline of the electro-optical device according to the first embodiment of the invention. FIG. 2 is an equivalent circuit diagram of a display panel employed in the electro-optical device of FIG. 3 is a cross-sectional view showing a cross-sectional structure in a state where the liquid crystal panel is stored in the outer frame when the liquid crystal panel is employed as the electro-optical device of FIG.

<First Embodiment>
1 and 2, the electro-optical device 11 includes a display panel 21 configured by bonding two substrates. When a liquid crystal panel is used as the display panel 21, the electro-optical device 11 includes a display panel 21 and an illumination unit 22 as shown in FIG.
Note that a self-luminous display panel may be employed as the electro-optical device, and in this case, the illumination unit 22 is not necessary.

The display panel 21 is configured by sealing liquid crystal (not shown) between the element substrate 23 and the counter substrate 24 that transmit light. The element substrate 23 and the counter substrate 24 arranged so as to face each other are bonded together by a sealing material (not shown). In the display panel 21, in the effective display area 14, for example, a plurality of scanning lines 33 (see FIG. 2) extending in the horizontal direction and a plurality of data (not shown) extending in the vertical direction are provided. The pixel is configured corresponding to the intersection of the plurality of scanning lines 33 and the plurality of data lines 34.

On the element substrate 23, a pixel electrode (ITO) 36 (see FIG. 2) constituting the pixel is disposed. A counter electrode (common electrode (ITO)) (not shown) is also provided on the counter substrate 24 side. On the pixel electrode 36 of the element substrate 23, an alignment film (not shown) that is in contact with the liquid crystal and is subjected to rubbing treatment is provided. On the other hand, on the side of the counter substrate 24, an alignment film (not shown) that is rubbed is provided in contact with the liquid crystal. Each alignment film is made of a transparent organic film such as a polyimide film. Further, a light shielding film (not shown) is also formed on the counter substrate 24 along the data lines and the scanning lines.

Note that polarizing plates (not shown) are provided on the observation surface side of the counter substrate 24 and on the opposite side of the element formation surface (hereinafter also referred to as a light receiving side surface) of the element substrate 23. These polarizing plates are set to a polarization axis corresponding to the rubbing direction of the alignment film formed on the element substrate 23 and the counter substrate 24.

The illumination unit 22 that functions as a backlight emits light from below the element substrate 23. The illumination unit 22 includes, for example, a plurality of light-emitting diodes (hereinafter referred to as LEDs) that constitute a light source and a light guide plate 25. The light guide plate 25 is fitted into the outer frame 26. The light from the LED is guided into the light guide plate 25, reflected and scattered by the reflection layers on the bottom and side surfaces of the light guide plate 25,
The light is emitted from the upper surface of the light guide plate 25.

A diffusion sheet 27 and a prism sheet 28 are disposed on the upper surface of the light guide plate 25. The diffusion sheet 27 and the prism sheet 28 diffuse the light from the light guide plate 25 and emit it upward.
On the prism sheet 28, the display panel 21 is arranged.

A light shielding plate 29 is also provided on the light guide plate 25. The light shielding plate 29 is the diffusion sheet 2
7 and the prism sheet 28 so as to surround the light guide plate 25. The light shielding plate 29 prevents light from the light guide plate 25 from entering the area other than the effective display area 14 of the display panel 21.

In the element substrate 23, a Y driver 31 and an X driver 32 are provided around the effective display area 14.
(Not shown in FIG. 1) is provided. As shown in FIG. 2, a plurality of scanning lines 33 extend from the Y driver 31 toward the effective display area 14, and a plurality of data lines 34 extend from the X driver 32 toward the effective display area 14. It is installed. The element substrate 23 is provided with a switching element 35 corresponding to the intersection of the scanning line 33 and the data line 34. The switching element 35 is turned on by a scanning signal supplied from the Y driver 31 to the scanning line 33.
Controlled off. The switching element 35 turned on is connected to the data line 3 from the X driver 32.
4 is supplied to the pixel electrode 36.

FIG. 2 shows an example in which the display panel 21 is a TFT liquid crystal panel. However, as long as the pixels in the effective display area 14 are driven by a driver, the same applies to other active matrix display panels. Can be configured. A terminal portion 37 is provided on one side of the display panel 21. The Y driver 31 and the X driver 32 and the terminal portion 37 are connected by wiring (not shown).

In the display device 11 configured as described above, an image signal is supplied to the data line 34 of the display panel 21, and a scanning signal is supplied to the scanning line 33. Thus, each pixel is driven based on the image signal, and the light transmittance changes. Light incident on the display panel 21 from the illumination unit 22 is modulated in accordance with the image signal in the effective display area 14 of the display panel 21. Thereby, an image can be visually recognized by observing the effective display area 14 from the observation surface side of the counter substrate 24. The counter substrate 24 is provided with a light shielding region 19 for shielding the periphery of the counter substrate 24 from light. The shape and size of the effective display area 14 are defined by the light shielding area 19.

In the present embodiment, the light shielding region 19 is provided with a light receiving element arrangement region 16 having an opening for taking outside light into the element substrate 23. In the light receiving element arrangement region 16, a PIN type light receiving diode 17 constituting a light receiving portion is provided on the element substrate 23. In the light receiving element arrangement region 16, light from the observation surface side of the counter substrate 24 is taken into the substrate through the opening of the light shielding region 19. FIG. 2 shows that a plurality of light receiving diodes 17 are formed in the light receiving element arrangement region 16.

The light receiving diode 17 can detect the illuminance of the incident light and output the detection result. By using the detection result of the light receiving diode 17, for example, it is possible to control the brightness of the illumination unit 22 according to the brightness of external light. For example, when it is detected that the outside light is bright, the brightness of the illumination unit 22 is increased according to the brightness of the outside light. Thereby, the visibility of display can be improved.

In the present embodiment, the display panel 2 is provided on a part of the light shielding plate 29 constituting the illumination unit 22.
A reflective portion 18 is provided at a position facing one light receiving element arrangement region 16. FIG.
In the example, the reflecting portion 18 is provided with an opening in a part of the light shielding plate 29 and is disposed in this opening. External light from the observation surface (light receiving surface) side of the counter substrate 24 enters the reflection portion 18 through the counter substrate 24 and the element substrate 23. The reflection part 18 is, for example, a mirror, an aluminum foil,
It is comprised by the metal plate etc., and can be comprised very simply. The reflector 18 reflects the light that has passed through the substrates 24 and 23 and guides it to the light receiving diode 17. Mainly, the light incident through the opening provided in the light shielding region 19 of the counter substrate 24 is incident on the reflecting portion 18.

A light shielding plate may be provided on the bottom surface of the reflecting portion 18, and the light from the light guide plate 25 disposed below the reflecting portion 18 may be prevented from entering the light receiving diode 17 by the light shielding plate.

FIG. 3 shows an example of a partial cross-sectional structure of the display device 11. FIG. 3 shows a cross section of a part of the effective display area 14 and a part of the light receiving element arrangement area 16 of FIG. FIG. 3 shows a TFT liquid crystal panel as an example of the display panel 21.

In the display panel 21, a base insulating film 71 is formed on a transparent substrate 23 such as a quartz substrate or a glass substrate. On the base insulating film 71, a semiconductor layer 73 constituting a TFT as a switching element is formed in the effective display region. The semiconductor layer 73 is made of polysilicon as a polycrystalline semiconductor. Note that this polysilicon is formed by crystallization by laser annealing of amorphous silicon as an amorphous semiconductor which is a non-single crystal semiconductor.

At both ends of the semiconductor layer 73, impurities are introduced to form a source region 72 and a drain region 74. A gate electrode 76 is formed on the semiconductor layer 73 via an oxide film 75. The gate electrode 76 has a two-layer structure in which, for example, the upper layer is molybdenum and the lower layer is aluminum, and is connected to the scanning line 33.

The source region 72 and the drain region 74 have an LDD structure. That is, the source region 72 and the drain region 74 have a portion with a relatively low impurity concentration in the vicinity of the channel region below the gate electrode 76. In order to form the LDD structure in the semiconductor layer 73, the semiconductor layer 73 is subjected to two impurity implantations for forming the low concentration region and the high concentration region of the source region 72 and the drain region 74. In the first impurity implantation, the source region 72 and the drain region 7
In the second impurity implantation, a relatively low concentration of impurities is implanted into both ends of the source region 72 and the drain region 74 using the gate electrode 76 as a mask.

An interlayer insulating film 77 is formed on the oxide film 75, and contact holes 78 a and 78 b are formed in the interlayer insulating film 77 on the source region 72 and the drain region 74, respectively.
The source region 72 is connected to the data line 34 through the contact hole 78a.

An interlayer insulating film 79 is formed on the wiring layer on which the data line 34 is formed and on the interlayer insulating film 77. A contact hole 80 is formed in the interlayer insulating film 79, and the drain region 74 is connected to the pixel electrode 36 formed on the interlayer insulating film 79 via the contact holes 78 b and 80.
It is connected to the.

On the other hand, a PIN type light receiving diode 17 is formed on the base insulating film 71 in the light receiving element arrangement region 16. The light receiving diode 17 is formed by the same manufacturing process as the TFT in the effective display area 14.

That is, the light receiving diode 17 is formed on the semiconductor layer 55 formed of the same layer as the semiconductor layer 73 by adding P
It has a P-type region 56 into which a type impurity has been introduced, an N-type region 58 into which an N-type impurity has been introduced, and an I-type region 57 into which an intrinsic semiconductor or a small amount of impurity has been introduced. P-type region 56 and N-type region 5
8 constitutes the anode or cathode of the light receiving diode 17, respectively.

On these regions 56 to 58, an oxide film 75 which is the same film as the effective display region 14 is formed. In the present embodiment, a mask conductive layer 59 is formed on the oxide film 75 on the light receiving diode 17. The mask conductive layer 59 is formed in the same process as the TFT gate electrode 76, and has a two-layer structure in which the upper layer is molybdenum and the lower layer is aluminum.

As described above, two impurity introduction steps are performed in order to form an LDD structure in the semiconductor layer 73 in the effective display region 14. The mask conductive layer 59 can prevent a low concentration of impurities from being introduced into the I-type region 57 in the second impurity introduction step.

The interlayer insulating film 77 has a contact hole 78 on the P-type region 56 and the N-type region 58.
c and 78d are opened. On the interlayer insulating film 77, the wiring 43, the same layer as the data line 34,
44 is formed, and the regions 56 and 58 are connected to the wirings 43 and 44 through contact holes 78c and 78d, respectively. The wirings 43 and 44 have, for example, a three-layer structure in which titanium, aluminum, and titanium are stacked.

An interlayer insulating film 79 is formed on the wiring layer on the interlayer insulating film 77 and on the interlayer insulating film 77. An alignment film 82 is formed on the pixel electrode 36 and the interlayer insulating film 79 in contact with the liquid crystal 84. The alignment film 82 is rubbed in a predetermined direction.

On the other hand, the opposing substrate 24 has a light shielding region 1 by a light shielding film 85 that partitions the effective display region 14.
9 is configured. A counter electrode 86 is formed on the light shielding film 85 and the counter substrate 24.
An alignment film 87 is formed on the counter electrode 86. The alignment film 87 is rubbed in a predetermined direction.

On the other hand, in the illumination unit 22, the light guide plate 25 is fitted in the recess of the outer frame 26. A diffusion sheet 27 is disposed on the light guide plate 25 at least in the effective display area 14.
7 is provided with a prism sheet 28. The diffusion sheet 27 and the prism sheet 28 diffuse the light from the light guide plate 25 and emit it upward.

In the present embodiment, the reflective portion 18 is provided on the outer frame 26 and the light guide plate 25 at least in a region facing the light receiving element arrangement region 16 of the display panel 21. Reflector 18
The light shielding plate 18b is disposed on the light guide plate 25 side, and the reflection plate 18a is disposed on the display panel 21 side. The light shielding plate 18b prevents the light from the light guide plate 25 from traveling to the light receiving diode 17 side. The reflection plate 18a reflects light incident from the observation surface side of the counter substrate 24 and transmitted through the element substrate 23 toward the light receiving diode 17 side. The external light that has entered the light receiving element arrangement region 16 and passed through the element substrate 23 is guided to the light receiving diode 17 side by the reflecting portion 18. If the light from the light guide plate 25 does not travel toward the light receiving diode 17 due to the positional relationship between the light guide plate 25 and the light receiving diode 17, the light shielding plate 18b.
Can be omitted.

According to such a configuration, light incident from the observation surface side of the counter substrate 24 via the light receiving element arrangement region 16 passes through the counter substrate 24 and proceeds to the element substrate 23 side. Part of this incident light is
The light enters the I-type region 57 from the mask conductive layer 59 side above the light receiving element 17. However, the mask conductive layer 59 formed on the I-type region 57 makes it difficult for light to enter the I-type region 57 from the mask conductive layer 59 side.

Most of the external light that passes through the counter substrate 24 and travels toward the element substrate 23 passes through the element substrate 23 and travels below the light receiving diode 17. The external light that has passed through the element substrate 23 is reflected by the reflecting plate 18 a disposed below the light receiving diode 17, returned to the element substrate 23 side, and enters the I-type region 57 of the light receiving diode 17 from below. . Thus, the light receiving diode 1
Thus, sufficient external light can be incident on the I-type region 57.

In the light receiving diode 17, a detection current corresponding to the photogenerated charge flows through a depletion layer generated in the I-type region 57. This detected current is output to the outside through wirings 43 and 44 connected to the regions 56 and 58, respectively. In this way, the illuminance of external light can be detected. The light shielding plate 18b prevents light from the light guide plate 25 from entering the light receiving diode 17, and the light receiving diode 17 can reliably detect the illuminance of external light.

By using the detection result of the light receiving diode 17, for example, it is possible to control the brightness of the illumination unit 22 according to the brightness of external light. For example, when it is detected that the outside light is bright, the brightness of the illumination unit 22 is increased according to the brightness of the outside light. Thereby, the visibility of display can be improved.

As described above, in the present embodiment, the reflector is provided below the PIN light-receiving diode, and the external light is reflected even when the mask conductive layer is provided on the I-type region of the light-receiving diode. To the light receiving diode. That is, it is possible to reliably detect the illuminance of the external light by causing sufficient external light to enter the light receiving diode without increasing the number of steps of removing the mask conductive layer.

In addition, the PIN type light receiving diode is in a region where the element substrate and the counter substrate face each other, that is,
It is provided in a region where external light can be incident. Therefore, it is possible to easily construct a structure for entering light to the PIN diode.

FIG. 4 is a graph showing the characteristics of the light-receiving diode, with voltage on the horizontal axis and current on the vertical axis. FIG. 4 shows a characteristic (dark current characteristic) when light is not incident on the light receiving diode by a broken line, shows a characteristic when there is no reflecting plate 18a by a thin line, and shows a characteristic when there is a reflecting plate 18a by a thick line. . 4 shows the distance between the regions 56 and 58, that is, the length of the I-type region 57 (light receiving layer length) L is 8 μm, and the distance of the semiconductor layer 55 in the direction perpendicular to the paper in FIG. 3 (light receiving layer width). When W is 50 μm, the characteristics when 10 lux of external light is incident are shown. The reflector 18a is an example using an aluminum foil.

The light receiving diode has photosensitivity in a region where the amount of current at the time of light incidence indicated by a solid line is larger than the amount of current at the time of darkness indicated by a broken line, that is, a reverse bias voltage application region. As shown in FIG. 4, it can be seen that the difference between the amount of current at the time of light incidence and the dark current is sufficiently large when the reflective plate 18 a is provided, compared to the case where the reflective plate 18 a is not provided. That is, according to the present embodiment, the reflector 18
It can be seen that a sufficient photosensitivity can be obtained with a.

FIG. 5 is a graph for explaining the dark current characteristics with the substrate temperature on the horizontal axis and the sensor output (current) on the vertical axis. FIG. 5 shows that the light receiving layer length L is 8 μm and the light receiving layer width W is 500 μm.
The characteristic when m is applied with a reverse voltage of −5 V and 10 lux of external light is incident is shown.

In the PIN diode constituting the sensor, the thermal current increases as the temperature rises, and at a predetermined temperature or higher, the thermal current becomes dominant and the photosensitivity is lost. FIG. 5 shows the output (dark current) of the light receiving diode in a state where no light is incident and the output (light irradiation current) with and without the reflection plate 18a with the external light fixed. As shown in FIG. 5, when the substrate temperature reaches 60 ° C., the output of each sensor has a very large thermal current component.

In this case, when the reflecting plate 18a is not provided, the values of the dark current and the light irradiation current are close to each other, and the external light cannot be accurately detected. On the other hand, when the reflector 18a is provided, even when the substrate temperature is 60 ° C., a sufficient difference between the dark current value and the light irradiation current value can be secured, and the external light can be accurately detected. Can do. Thus, in this embodiment, even when the substrate temperature is 60 ° C., dark external light of about 10 lux can be detected. The detection limit when aluminum foil was used as the reflector 18a was 10 lux or less when the substrate temperature was 50 ° C.

<Second Embodiment>
FIG. 6 is a perspective view showing an outline of an electro-optical device according to the second embodiment of the invention. FIG.
In FIG. 1, the same components as those in FIG.

The present embodiment is different from the first embodiment only in the position and shape of the light receiving element arrangement region and the position and shape of the reflecting portion facing the light receiving element arrangement region.

The electro-optical device 111 includes the display panel 121 and the illumination unit 1 having the same structure as that of the first embodiment.
22. The element substrate 123, the counter substrate 124, the light shielding region 119, and the light receiving element arrangement region 116 correspond to the element substrate 23, the counter substrate 24, the light shielding region 19, and the light receiving element arrangement region 16 of the first embodiment, respectively. The light receiving element arrangement region 116 is a region where the counter substrate 124 in the region outside the effective display region 14 is not opposed to the display panel 121.
Is provided along a part of one long side. As in the first embodiment, a PIN type light receiving diode is provided in the light receiving element arrangement region 116.

Further, the light shielding plate 129 and the reflection unit 118 constituting the illumination unit 122 correspond to the light shielding plate 29 and the reflection unit 18 of the first embodiment, respectively. The light shielding plate 129 is provided on the edge portion of the light guide plate 25 so as to surround the diffusion sheet 27 and the prism sheet 28. The reflection unit 118 is provided at a position and a shape facing the light receiving element arrangement region 116. The reflection unit 118 is configured by, for example, a mirror, an aluminum foil, a metal plate, and the like, and is provided in the light receiving element arrangement region 116 by reflecting light incident from the counter substrate 124 side and passing through the element substrate 123. The reflected light is guided to the light receiving diode.

  Other configurations are the same as those of the first embodiment.

Also in the embodiment configured as described above, the same effect as in the first embodiment can be obtained. Further, in the present embodiment, the light receiving element arrangement region 16 is provided on the element substrate 123 that is not opposed to the counter substrate 124. That is, the light from the light guide plate 25 does not enter the light receiving element arrangement region 16. Therefore, the light receiving diode in the light receiving element arrangement region 16 can detect outside light without being affected by light from the light guide plate. Further, the light shielding plate can be omitted as the reflecting portion 118.

<Third Embodiment>
FIG. 7 is a sectional view showing an outline of an electro-optical device according to the third embodiment of the invention. FIG.
In FIG. 3, the same components as those in FIG.

In the first embodiment, the surface of the reflecting plate is flat, for example. In this case, the reflection direction of the light incident on the reflecting plate is determined by the incident angle. As a result, most of the incident light may not enter the light receiving diode.

Therefore, in the present embodiment, by providing irregularities on the surface of the reflecting plate, most of the external light is efficiently incident on the light receiving diode. In the present embodiment, the illumination unit 132 is different from the illumination unit 22 of the first embodiment in that a reflection unit 133 is used instead of the reflection unit 18.

The reflection unit 133 includes a light shielding plate 133b on the light guide plate 25 side and a reflection plate 133a on the light receiving diode 17 side. The light shielding plate 133b has the same configuration as the light shielding plate 18b of FIG. The reflecting plate 133a has irregularities on the surface. For example, the reflecting plate 133a may have a wave-shaped surface, or the surface may be rough, that is, may have a sufficiently small size.

Also in the embodiment configured as described above, light incident from the observation surface side of the counter substrate 24 passes through the counter substrate 24 and the element substrate 23 and enters the reflection plate 133a. In the present embodiment, the light incident on the reflecting plate 133 a is scattered, for example, and most of the external light is incident on the light receiving diode 17. Further, depending on the surface shape of the reflecting plate 133 a, the light incident on the reflecting plate 133 a is collected and enters the light receiving diode 17.

Thus, in the present embodiment, external light can be efficiently taken into the light-receiving diode 17, and detection of external light with higher sensitivity is possible.

  Other functions and effects are the same as those of the first embodiment.

<Fourth embodiment>
FIG. 8 is a sectional view showing an outline of an electro-optical device according to the fourth embodiment of the invention. FIG.
In FIG. 3, the same components as those in FIG.

In the first embodiment, the reflecting plate is provided in the reflecting portion, so that the external light that has passed through the element substrate is reflected to the light receiving diode side. On the other hand, in the present embodiment, the reflecting portion is made of a paint having a relatively high light reflectance. In this embodiment,
The illumination unit 142 is different from the illumination unit 22 of the first embodiment in that a reflection unit 143 is used instead of the reflection unit 18.

That is, the reflecting portion 143 is configured by a paint applied to the back surface of the element substrate 23. As the paint, for example, a white paint having a high light reflectance can be employed. Depending on the material of the paint, unevenness of a sufficiently small size may be formed on the back surface of the element substrate 23,
In this case, incident light can be scattered and light can be efficiently incident on the light receiving diode 17.

Also in the embodiment configured as described above, the light incident from the observation surface side of the counter substrate 24 passes through the counter substrate 24 and the element substrate 23 and enters the reflecting portion 143. In the present embodiment, the light that has passed through the element substrate 23 is reflected on the back surface of the element substrate 23 by the paint constituting the reflecting portion 143 and enters the light receiving diode 17.

Thus, also in the present embodiment, external light can be efficiently taken into the light receiving diode 17 and high-sensitivity external light detection is possible.

  Other functions and effects are the same as those of the first embodiment.

In the fourth embodiment, the reflective portion 143 is configured by applying paint to the back surface of the element substrate 23, but it is obvious that the paint may be applied to the outer frame 26 side.

Further, an electronic apparatus using the above electro-optical device is also included in the present invention. FIG. 9 is a perspective view showing a configuration of a cellular phone 1200 using the electro-optical device of each of the above embodiments.

As shown in this figure, the mobile phone 1200 includes the above-described liquid crystal panel 150 together with the earpiece 1204 and the mouthpiece 1206 in addition to a plurality of operation buttons 1202. In the electro-optical device, components other than the liquid crystal panel 150 are built in the telephone, so that they do not appear as appearance.

In addition, as an electronic device, for example, a projection display device including a light source, a light valve that modulates light emitted from the light source, and an optical system for projecting light modulated by the light valve It is. In addition, other electronic devices include televisions, viewfinder type / monitor direct view type video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, digital Examples include a still camera and a device equipped with a touch panel. Needless to say, the electro-optical device according to the present invention is applicable to these various electronic devices.

The electro-optical device of the present invention is not only a TFT (thin film transistor) liquid crystal panel,
The present invention can be similarly applied to a liquid crystal display panel provided with a TFD (thin film diode) as a switching element. In addition to liquid crystal display panels, electroluminescence devices, organic electroluminescence devices, plasma display devices, electrophoretic display devices, devices using electron emission (Field Emission Display and Surface-Conduction)
Electron-Emitter Display etc.), DLP (registered trademark) (Digital Light Processing) (
The present invention can be similarly applied to various electro-optical devices such as a DMD (Digital Micromirror Device).

1 is a perspective view showing an outline of an electro-optical device according to a first embodiment of the invention. FIG. 2 is an equivalent circuit diagram of a display panel employed in the electro-optical device of FIG. FIG. 2 is a cross-sectional view showing a cross-sectional structure in a state in which a liquid crystal panel is stored in an outer frame when a liquid crystal panel is employed as the electro-optical device in FIG. 1. The graph which shows the characteristic of a light receiving diode by taking a voltage on a horizontal axis and taking an electric current on a vertical axis | shaft. A graph for explaining dark current characteristics with the substrate temperature on the horizontal axis and the sensor output (current) on the vertical axis. FIG. 6 is a perspective view illustrating an outline of an electro-optical device according to a second embodiment of the invention. FIG. 6 is a cross-sectional view illustrating an outline of an electro-optical device according to a third embodiment of the invention. FIG. 10 is a cross-sectional view illustrating an outline of an electro-optical device according to a fourth embodiment of the invention. The perspective view which shows the example of an electronic device.

Explanation of symbols

14 ... Effective display area, 16 ... Light receiving element arrangement area, 17 ... Light emitting diode, reflection part ... 18
.

Claims (8)

Ri Na and switching elements are formed on the intersections of the scanning lines and the data lines, the electro-optical comprising: a display panel and an illumination unit provided below the element substrate having an element substrate on which external light incident from above In the device
A light receiving element made of a PIN diode formed on the element substrate;
Reflecting means provided between the light receiving element and the illuminating unit and reflecting external light transmitted through the element substrate to the light receiving element ;
A light-shielding means provided between the reflecting means and the illumination unit, for shielding light emitted from the illumination unit;
Ru electric optical device name comprises a. The display panel includes a light shielding region that defines an effective display region, and the light shielding region has an opening in a region where the light receiving element is disposed.
The electro-optical device according to 請 Motomeko 1. Having a counter substrate disposed to face the element substrate;
The element substrate has a region that does not face the counter substrate, and the light receiving element is formed in a region that does not face the counter substrate.
The electro-optical device according to 請 Motomeko 1. The reflecting means has irregularities on the surface.
The electro-optical device according to any one of 請 Motomeko 1 to 3. The reflection means is configured to collect incident external light and reflect it to the light receiving element.
The electro-optical device according to any one of 請 Motomeko 1 to 3. The light receiving element includes a PIN diode having an I-type region, and the I-type region is masked.
The electro-optical device according to any one of 請 Motomeko 1 to 5. It becomes configured to control the brightness of the lighting unit using the detection result of the previous SL receiving element
The electro-optical device according to any one of 請 Motomeko 1 to 6. An electro-optical device according to claim 1.
Electronic equipment.

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