JP2007094098A - Liquid crystal display device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve picture quality by improving precision of photosensors by correcting temperature and variations and then suppressing a decrease in S/N. <P>SOLUTION: A liquid crystal display device is equipped with a liquid crystal panel constituted by charging liquid crystal between first and second substrates, a back light 8 which irradiates a surface of the first substrate of the liquid crystal panel with light, an optical detecting means of detecting the illuminance of ambient light, and a lighting control means 12 of controlling the back light 8 according to the detection result of the optical detecting means, and the optical detecting means is equipped with first and second photosensors 21 and 22 provided to the first substrate or second substrate respectively; and the first photosensor 21 is irradiated with at least external light A and the second photosensor 22 is shielded by an external light shielding part 28 from at least the external light A. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and an electronic apparatus.

  Among liquid crystal display devices, there is a transmissive type in which light is irradiated from a back surface of a liquid crystal panel that displays an image by a backlight (illumination device). The liquid crystal panel has a configuration in which liquid crystal is sealed between an active matrix substrate and a counter substrate facing the active matrix substrate, and the backlight is provided to face the active matrix substrate of the liquid crystal panel. In a transmissive liquid crystal display device having such a configuration, it is difficult to use the backlight if the illumination intensity of the backlight is higher than necessary in a dark environment. Therefore, it is necessary to change the brightness of the backlight according to the ambient brightness. There is. In addition, in a transmissive liquid crystal display device, the power consumption by the backlight accounts for most of the power consumption. By reducing the power consumption by the backlight, the power consumption of the liquid crystal display device can be reduced. it can. In addition, the situation where the backlight needs to be controlled is the same for the transflective (or transflective) display having the characteristics of both the transmissive type and the reflective type that displays using reflection from outside light. Since the backlight can be turned off if the light is sufficient, the power consumption saving effect is even greater.

  Therefore, the conventional liquid crystal display device is provided with means for automatically adjusting the luminance of the backlight according to the ambient brightness. Specifically, the brightness of the surrounding environment (illuminance of outside light) And a backlight control circuit that controls the backlight according to the detection result of the photosensor (see, for example, Patent Documents 1 and 2).

A photosensor consists of a single photodiode, phototransistor, photo IC (Integrated Circuit), etc. When these packages are mounted on the overhanging portion of an active matrix substrate, the mounting location is significantly limited. Since it is necessary to provide an opening in the upper electronic device to introduce external light, such a restriction is not preferable from the viewpoint of strength and design. Also, if the package is thicker than the counter substrate, the module thickness increases. Therefore, it is preferable to form a photosensor on the active matrix substrate by a thin film process. For example, a configuration in which a PIN junction thin film diode, a field effect thin film diode, a field effect thin film transistor, a PN junction diode, or the like is used and a photosensor is formed using an off-current under a reverse bias condition is conceivable. That is, if a PIN junction thin film diode or a field effect thin film diode is used, the off-current Id is detected under a reverse bias condition (bias voltage Vd <0), and if it is a field effect thin film transistor, a reverse bias is applied to the gate electrode (N Channel-type gate-source voltage Vgs <0, P-channel type gate-source voltage Vgs> 0), and off current when a constant bias (drain-source voltage Vds) is applied between the drain and source electrodes What is necessary is just to detect Ids.
At this time, the following formulas are established for the off-currents IR and Ids detected by the photosensor. Where temp: temperature, L: illuminance, Vd: anode-cathode voltage, Vgs: gate-source voltage, Vds: drain-source voltage.

  Further, experimentally, it is known that Iphoto is proportional to the illuminance L and Ithermal is an exponential function of absolute temperature, and the following two equations are established respectively. However, EB: barrier barrier energy, k: Boltzmann constant.

In general single photodiodes, phototransistors, and photo ICs, Iphoto 'has almost no variation under constant bias conditions, and Iphoto >> Ithermal. Therefore, L can be obtained by measuring Id and Ids. it can. From here, according to the liquid crystal display device equipped with the photo sensor and the backlight control circuit described above, the illuminance of outside light is detected by the photo sensor, and the backlight control circuit automatically adjusts the brightness of the backlight. For example, in a situation where there is no external light, the backlight luminance is minimized, so that the user is not dazzled and the power consumption more than necessary can be prevented. Further, the illuminance is gradually increased as the external light becomes brighter, and it is possible to prevent the transmissive display from being difficult to visually recognize due to the external light. Further, in the transflective liquid crystal display device, when the brightness becomes a certain level or more, the backlight is turned off, and the power consumption can be reduced by switching to the reflection mode only.
JP-A-4-291389 JP 2004-96593 A

However, in the conventional liquid crystal display device described above, since the active matrix substrate must be transparent in order to transmit the light of the backlight, generally an alkali-free glass substrate or a quartz substrate is used as the base material of the active matrix substrate. In this case, it is difficult to form a complete single crystal semiconductor thin film as an active layer due to restrictions such as process temperature, and a polycrystalline thin film or an amorphous thin film containing many defects must be used. . Therefore, the active layer of the photosensor formed on the active matrix substrate must also have many defects, compared with a photodiode phototransistor using single crystal silicon or the like.
1) The current Ithermal due to heat is relatively large compared to the current Iphoto due to light and cannot be ignored.
2) Individual variation of Iphoto 'under the same bias condition (gradient with respect to illuminance) is large.
As a result, the accuracy of the photo sensor is reduced, the S / N ratio (signal / noise ratio) is significantly reduced, and the backlight illuminance control with respect to external light cannot be performed correctly, so that the visibility is reduced. It will be.

  In the present invention, the above-described conventional problems are taken into consideration, and the correction due to the temperature caused by the relatively large current Ithermal due to the heat compared to the current Iphoto due to the light is performed to improve the accuracy of the photosensor, The object is to suppress the decrease in the S / N ratio and improve the visibility of the liquid crystal display device. In addition, for the purpose of improving the visibility of the liquid crystal display device by correcting the variation caused by the large individual variation of Iphoto ', improving the accuracy of the photosensor, suppressing the decrease in the S / N ratio. Yes.

A liquid crystal display device according to the present invention includes a liquid crystal panel in which liquid crystal is sealed between first and second substrates, an illumination device that irradiates light onto the surface of the first substrate of the liquid crystal panel, and a surrounding device. A light detecting means for detecting the illuminance of the light, and an illumination control means for controlling the lighting device in accordance with a detection result by the light detecting means, wherein the light detecting means includes the first substrate or the first substrate. The first photosensor is provided with at least external light, and the second photosensor is provided with at least external light by an external light shielding unit. Is characterized by being blocked from irradiation.
Due to these features, by calculating the current difference between the first photosensor and the second photosensor, it is possible to correctly calculate only the value of Iphoto from which Ithermal has been removed. Since it is possible to calculate the correct external light illuminance regardless of the temperature and backlight illuminance, correct illuminance adjustment according to the external light illuminance can be performed, so that a liquid crystal display device with high visibility can be realized.

  Further, the present invention may be configured such that light from the lighting device is irradiated to the second photosensor. As a result, the illuminance dependence term Iphoto 'of the photosensor can be correctly estimated using the illuminance of the illuminating device, so that the external light illuminance can be correctly calculated even if there are individual variations in the sensor.

According to the present invention, in the above-described liquid crystal display device, the illuminance of the illumination device is changed to first and second illuminances different from each other, and the output value of the second photosensor at the first illuminance and the first illuminance are changed. It is good also as a structure provided with the means to calculate external light illumination intensity from the difference with the output value of the said 2nd photosensor in 2 illumination intensity.
With such a configuration, the illuminance dependence term Iphoto 'of the photosensor can be correctly estimated from the current difference of the second photosensor when the illuminance of the backlight is changed. Light illuminance can be calculated.

In the present invention, at least one of the first photosensor and the second photosensor may be configured such that illumination of light from the illumination device is blocked by an illumination light shielding unit.
With such a configuration, the illuminance dependence term Iphoto 'of the photosensor can be correctly estimated from the current difference between the first photosensor and the second photosensor, so the ambient light illuminance can be calculated correctly even if there are individual variations in the sensor. I can do it. In addition, when at least one of the photosensors is arranged, it is possible to correctly estimate the illuminance of outside light even when the illuminance of the backlight cannot be uniformly applied.

Further, in the present invention, the first photosensor is blocked from irradiating light from the illuminating device by an illuminating light shielding unit, and the second photosensor is irradiated with light from the illuminating device, Means is provided for setting the illuminance of the lighting device to a specific value and detecting the magnitude of the external light illuminance with respect to the specific value from the difference between the output value of the first photosensor and the output value of the second photosensor. It is good also as composition which has.
With such a configuration, for example, if the output difference obtained by subtracting the output value of the second photosensor from the output value of the first photosensor is a positive value (plus), the illuminance of external light is set. On the other hand, if the output difference is a negative value (minus), it is determined that the illuminance of outside light is smaller than the set specific value. In addition, when the output difference is calculated by subtracting the output value of the first photosensor from the output value of the second photosensor, if the difference is positive, the illuminance of outside light is greater than the set specific value. On the other hand, if the output difference is negative, it is determined that the illuminance of outside light is larger than the set specific value. As a result, for example, it is possible to accurately determine whether or not the illuminance of outside light has reached at least a specific value, and the magnitude of the external light illuminance with respect to each specific value is detected while varying the size of the specific value. By performing the means, the accurate external light illuminance can be detected.

Further, the present invention is an active matrix substrate in which the first substrate or the second substrate is provided with an active element on a surface on the liquid crystal side, and the active element includes the active layer and the first substrate. A bottom-gate transistor or a four-terminal transistor having a bottom gate electrode between a substrate of one substrate and the illumination light shielding portion is a film formed of the same material as the bottom gate electrode Also good.
With such a configuration, the illumination light shielding part and the bottom gate electrode can be formed in the same process, and the manufacturing process can be shortened and the cost can be reduced.

Further, the present invention is an active matrix substrate in which the first substrate or the second substrate is provided with an active element on a surface on the liquid crystal side, and the active element includes the active layer and the first substrate. The transistor may have a top gate structure having a transistor light shielding layer between a substrate and a substrate, and the illumination light shielding portion may be a film formed of the same material as the transistor light shielding layer.
With such a configuration, the illumination light shielding part and the transistor light shielding layer can be formed in the same process, and the manufacturing process can be shortened and the cost can be reduced.

According to the present invention, the first substrate is an active matrix substrate in which an active element is disposed on the surface on the liquid crystal side, the active element is a transistor having a gate electrode, and the external light shielding is performed. The portion may be a film formed of the same material as the gate electrode.
With such a configuration, the external light shielding portion and the gate electrode can be formed in the same process, and the manufacturing process can be shortened and the cost can be reduced.

In the present invention, the first substrate is an active matrix substrate in which active elements are disposed on the liquid crystal side surface, and the external light shielding portion is made of the same material as the data lines of the active matrix substrate. It is good also as a structure which is the film | membrane formed by.
With such a configuration, it is possible to form the external light shielding portion and the data line in the same process, thereby shortening the manufacturing process and reducing the cost.

Furthermore, the present invention may be configured such that a reflective electrode is provided on the liquid crystal side surface of the first substrate, and the external light shielding portion is a film formed of the same material as the reflective electrode.
With such a configuration, it is possible to form the external light shielding portion and the reflective electrode in the same process, thereby shortening the manufacturing process and reducing the cost.

According to the present invention, a black matrix layer is provided in a display area for displaying an image on at least one of the liquid crystal side surfaces of the first substrate and the second substrate, and the external light shielding portion is provided. The film may be formed of the same material as the black matrix layer.
With such a configuration, it is possible to form the external light shielding portion and the black matrix layer in the same process, thereby shortening the manufacturing process and reducing the cost.

According to the present invention, a color filter layer is provided in a display area for displaying an image on at least one of the liquid crystal side surfaces of the first substrate and the second substrate, and the external light shielding portion is provided. The film may be formed of the same material as the color filter layer.
With such a configuration, it is possible to form the external light shielding portion and the color filter layer in the same process, and it is possible to shorten the manufacturing process and reduce the cost.

Further, according to the present invention, the color filter layer includes a first color filter layer corresponding to blue display, a second color filter layer corresponding to green display, and a third color filter layer corresponding to red display. And the external light shielding portion is a film made of the same material as the first color filter layer, a film made of the same material as the second color filter layer, or the third color. Of the films made of the same material as the filter layer, any two or more kinds of films may be overlapped.
With such a configuration, two or more kinds of films are overlapped to form the external light shielding part. Therefore, the light shielding property of the external light shielding part is enhanced, and the illuminance of the external light can be detected with high accuracy.

Further, the present invention may be configured such that the external light shielding portion is formed of the same resin as a sealing material interposed between the first and second substrates.
With such a configuration, the external light shielding portion and the sealing material can be formed in the same process, and the manufacturing process can be shortened and the cost can be reduced.

In addition, an electronic apparatus according to the present invention includes the above-described liquid crystal display device.
Due to such a feature, the same operation and effect as the above-described liquid crystal display device can be achieved, so that visibility can be maintained well under any circumstances and power consumption can be reduced, for example, battery driving time. Can be lengthened.

  Hereinafter, embodiments of a liquid crystal display device and an electronic apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway view showing a liquid crystal module 1 of a liquid crystal display device.
As shown in FIG. 1, the liquid crystal module 1 includes a nematic liquid crystal material 4 (liquid crystal) sandwiched between an active matrix substrate 2 (first substrate) and a counter substrate 3 (second substrate), and a sealing material 5 Both substrates 2 and 3 are bonded together to enclose the liquid crystal material 4. On the pixel electrode of the active matrix substrate 2, an alignment film (not shown) is formed by applying an alignment material made of polyimide or the like and rubbing. The counter substrate 3 includes a color filter (not shown) corresponding to the pixel, a black matrix (not shown) for preventing light leakage and improving contrast, and a counter electrode made of an ITO film to which a common potential is supplied. And an alignment material made of polyimide or the like is applied to the surface in contact with the liquid crystal material 4 and is rubbed in a direction perpendicular to the rubbing direction of the alignment film of the active matrix substrate 2.

  Further, an upper deflection plate 6 is arranged outside the counter substrate 3, and a lower deflection plate 7 is arranged outside the active matrix substrate 2, and they are arranged in a crossed Nicol shape so that their polarization directions are orthogonal to each other. Further, a backlight unit 8 (illuminating device) that constitutes a surface light source is disposed below the lower deflection plate 7. The backlight unit 8 may be a cold cathode tube or an LED (light emitting diode) attached with a light guide plate or a scattering plate, or may be a unit that emits light entirely by an EL (Electroluminescence) element. The backlight unit 8 is connected to an electronic device main body (not shown) through a connector 9 and is supplied with power. Further, although not shown, if necessary, the periphery may be covered with an outer shell, or a protective glass or acrylic plate may be attached on the upper deflection plate 6 to improve the viewing angle. An optical compensation film may be attached.

Further, the active matrix substrate 2 is provided with an overhanging portion 2a protruding from the counter substrate 3, and a signal input terminal (not shown) in the overhanging portion 2a includes an FPC (Flexible Printed Circuit) 10 and an external drive IC 11, 11 is mounted, and a plurality of signal input terminals on the active matrix substrate 2 are electrically connected. In FIG. 1, the external drive IC 11 is composed of two ICs, but may be one or three or more. The FPC 10 is connected to a control board 13 having a power supply IC, a signal control IC, a capacitor, a resistor, a ROM (read only memory), a backlight control unit 12 (illumination control means), etc., and receives a reference potential, a control signal, and video data. Supply to the active matrix substrate 2. Further, the control board 13 is also connected to the backlight unit 8 through the connector 14 so that the backlight unit 8 on the control board 13 can be switched ON / OFF and adjusted in luminance (illuminance) by the backlight control unit 12. It has become.
In the present embodiment, the backlight unit 8 is disposed outside the active matrix substrate 2, but conversely, a configuration in which the backlight unit 8 is disposed outside the counter substrate 3 is also possible. In this case, the first substrate in the claims is the counter substrate 3, and the second substrate is the active matrix substrate 2.

FIG. 2 is a schematic diagram showing the active matrix substrate 2.
As shown in FIG. 2, m (m is a natural number, for example, m = 480) scanning lines 15 and n (n is a natural number, for example, n = 1920) data lines 16 are arranged on the active matrix substrate 2. The m capacitance lines 17 are alternately arranged in parallel with the scanning lines 15 and in pairs with the scanning lines 15.

  Further, the scanning line 15 is connected to the scanning line driving circuit 18, and the data line 16 is connected to the data line driving circuit 19, and a driving signal necessary for display is given thereto. The scanning line driving circuit 18 and the data line driving circuit 19 are supplied with various signals and signals for supplying a power supply potential from the external driving IC 11 and the control board 13 shown in FIG. Is done. The scanning line driving circuit 18 and the data line driving circuit 19 are CMOS (Complementary Metal Oxide Semiconductor) circuits integrally formed on the active matrix substrate 2 using thin film transistors.

  The capacitor lines 17 are short-circuited to each other and connected to a common potential input terminal (not shown) via a common potential wiring (not shown), and a common potential signal (VCOM = -4.5V to -0.5V inversion). Signal). Further, a first photosensor 21 and a second photosensor 22 are mounted on the active matrix substrate 2, respectively, and the illuminance of ambient light by these first and second photosensors 21 and 22. A light detection unit (light detection means) is detected. Output signals from the first photosensor 21 and the second photosensor 22 are supplied to the backlight control unit 12 on the control board 13 shown in FIG. 1 via the signal input terminal 20 and the FPC 10 shown in FIG. Is done.

FIG. 3 is an enlarged view of a portion A in FIG. 2, and is a schematic diagram showing an intersection between the scanning line 15 and the data line 16.
As shown in FIG. 3, a pixel switching element 23 (active element) made of an N-channel field effect polysilicon thin film transistor is formed corresponding to each intersection of the scanning line 15 and the data line 16, and the gate electrode 31 is The scanning electrode 15, the source electrode 32 is connected to the data line 16, and the drain electrode 33 is connected to the pixel electrode 24. The pixel electrode 24 is connected to the counter electrode 25 (common electrode) of the counter substrate 3 through the liquid crystal material 4, thereby forming a liquid crystal capacitor 26. Further, an auxiliary capacitor 27 composed of the pixel electrode 24 on the pixel potential side and the capacitor line 17 is formed in parallel with the liquid crystal capacitor 26.

Further, a reflective electrode (not shown) is formed on a part of the pixel electrode 24, and this region corresponds to a reflective display, and the other region corresponds to a transmissive display. Yes.
In this embodiment, a reflection electrode is formed on the active matrix substrate 2 and a so-called internal reflection plate structure is used. However, as a configuration of a so-called total transmission type liquid crystal display device in which the reflection electrode is not provided on the active matrix substrate 2. Alternatively, a so-called slightly reflecting liquid crystal display device in which a slightly reflecting film is inserted under the lower polarizing plate 7 shown in FIG.

FIG. 4 is a graph showing the relationship between the illuminance (luminance) of the backlight 8 and the illuminance of external light when the backlight unit 8 is controlled by the backlight control unit 12.
As shown in FIGS. 2 and 4, the illuminance of external light is detected using two photosensors 21 and 22, and the luminance of the backlight unit 8 is automatically adjusted by the backlight control unit 12. Specifically, in a situation where there is no external light, the illuminance of the backlight unit 8 is minimized, so that the user is not dazzled and unnecessary power consumption is prevented. As the external light becomes brighter, the illuminance of the backlight unit 8 is gradually increased to prevent the transmissive display from becoming difficult to visually recognize due to the external light. When the ambient environment becomes more than a certain level of brightness, the backlight unit 8 is turned off and only the reflection mode is switched to reduce power consumption.

  The first photosensor 21 is configured to be irradiated with at least external light, and the second photosensor 22 is configured to block at least external light from being irradiated with external light. The ambient light illuminance is calculated based on the output values output from the first and second photosensors 21 and 22, respectively, and the control signal sent to the backlight unit 8 is corrected. Below, the 1st-3rd embodiment is each demonstrated about the structure which measures external light illumination intensity.

[First Embodiment]
First, a schematic configuration for measuring the external light illuminance in the first embodiment will be described.
FIG. 5 is a schematic diagram showing a configuration for measuring the illuminance of outside light in the first embodiment.
As shown in FIG. 5, of the two photosensors 21 and 22 respectively disposed on the active matrix substrate 2 (shown in FIG. 2), the first photosensor 21 is the external light A and the backlight unit. 8 (hereinafter referred to as backlight light B) is irradiated, and the second photosensor 22 is configured such that the external light A is reflected by the external light shielding film 28 (external light shielding portion). It is in a state where it is blocked and the backlight light B is irradiated.

  In the configuration described above, the current I1 (output value) flowing through the diode or transistor constituting the first photosensor 21 and the current I2 (output value) flowing through the diode or transistor constituting the second photosensor 22 are: Each is expressed by the following equation. Here, LA is the illuminance of the external light A on the first photosensor 21, LB1 is the illuminance of the backlight light B irradiated on the first photosensor 21, and LB2 is the second photo. The illuminance of the backlight light B irradiated on the sensor 22, Vd 1 is the anode-cathode voltage of the diode constituting the first photosensor 21, and Vgs1 is the transistor constituting the first photosensor 21. The gate-source voltage, Vds1 is the drain-source voltage of the transistor constituting the first photosensor 21, temp1 is the absolute temperature of the first photosensor 21, and Vd2 is the second photosensor. 22 is a voltage between the anode and the cathode of the diode that constitutes 22, and Vgs2 is the gate of the transistor that constitutes the second photosensor 22. An over scan voltage, Vds2 is the drain-source voltage of the transistor constituting the second photosensor 22, temp2 is the absolute temperature of the second photosensor 22. The first photosensor 21 and the second photosensor 22 have the same device structure except for the light shielding state, and the same current flows under the same conditions.

Here, when the same bias voltage is applied to the first photosensor 21 and the second photosensor 22, Vd1 = Vd2 = Vd, Vgs1 = Vgs2 = Vgs, and Vds1 = Vds2 = Vds. Specifically, for example, Vd = -4V, Vgs = -5V, Vds = -4V, and the like. In addition, since the first photosensor 21 and the second photosensor 22 are arranged on the same substrate active matrix substrate 2, temp1 = temp = temp because the temperatures can be equal. If the circuit is configured so that Vd, Vgs, and Vds are constant, Iphoto ′ (Vd) and Iphoto ′ (Vgs, Vds) can also be handled as constants (hereinafter simply referred to as Iphoto ′).
From the above equation and assumption, the difference (I1−I2) between the current I1 flowing through the first photosensor 21 and the current I2 flowing through the second photosensor 22 is expressed by the following equation.

  Since the currents I1 and I2 in the above formula are output from the first and second photosensors 21 and 22, respectively, if this is measured, the external light illuminance LA is calculated from the above formula. The calculated external light illuminance LA is an accurate value considering heat leak, and the control signal sent to the backlight unit 8 is corrected based on the external light illuminance LA. Thereby, the control signal corrected by the temperature can be sent to the backlight unit 8, and the illuminance control of the backlight unit 8 can be performed more accurately than before, and the visibility can be improved. Can do.

In addition, Iphoto 'actually has a certain range of variation due to variations in the manufacturing process, but the backlight control unit 12 is provided with means for calculating Iphoto' and uses a predetermined constant. It is also possible to calculate Iphoto ′ for each product. That is, the backlight unit 8 is operated to change the illuminance of the backlight light B from the first illuminance LB1 to the second illuminance LB2. Then, the current I21 flowing through the second photosensor 22 at the first illuminance LB1 is measured, and the current I22 flowing through the second photosensor 22 at the second illuminance LB2 is measured. For example, first, the backlight unit 8 is turned on, the current I21 flowing through the second photosensor 22 at that time is measured, and then the backlight unit 8 is turned off and flows through the second photosensor 22 at that time. The current I22 is measured.
At this time, the current difference I21-I22 at each time (ON and OFF) is expressed by the following equation. However, the backlight illuminance when the backlight unit 8 is ON is LB1, and the backlight illuminance LB2 when the backlight unit 8 is OFF is naturally zero.

The currents I21 and I22 in the above equation are respectively output from the second photosensor 22, and the illuminance LB1 in the above equation is known, so the constant Iphoto ′ is calculated from the above equation. As a result, a constant Iphoto ′ for each product is obtained, and even if the constant Iphoto ′ varies between products, correction is possible, and the external light illuminance LA can be obtained with higher accuracy.
Here, the period during which the backlight is turned off is preferably performed during the vertical blank period of the liquid crystal display device in view of display quality or S / N ratio at the time of correction.

  Next, the specific configuration of the liquid crystal display device according to the first embodiment described above will be described below by showing first to fourth specific examples.

First, a first specific example of the liquid crystal display device according to the first embodiment will be described.
FIG. 6 is an enlarged cross-sectional view showing a first specific example of the liquid crystal display device according to the first embodiment.
As shown in FIG. 6, in the liquid crystal display device, as described above, the liquid crystal material 4 is sealed between the active matrix substrate 2 and the counter substrate 3, and the lower polarizing plate 7 is disposed on the outer side (lower side) of the active matrix substrate 2. Is arranged, the upper polarizing plate 6 is arranged on the outer side (upper side) of the counter substrate 3, and the backlight unit 8 is arranged below the lower polarizing plate 7.

  The pixel switching element 23 provided on the active matrix substrate 2 is an n-channel field effect transistor, and has an intrinsic thickness of 50 nm disposed on a base insulating layer 34a made of a silicon nitride film having a thickness of 200 nm. A source electrode 32 and a drain electrode 33 made of n + thin film silicon are respectively disposed on both sides of a channel portion 30 made of a polycrystalline thin film silicon thin film, and Cr (chrome) having a thickness of 300 nm is further provided above the channel portion 30. The gate electrode 31 made of a thin film is provided. The gate electrode 31 is opposed to the channel part 30 with a gap, and an insulating film 34b of silicon oxide 50 nm is interposed between the channel part 30 and the gate electrode 31.

  The data line 16 made of a 500 nm Al (aluminum) thin film is electrically connected to the source electrode 32, and the drain electrode 33 is connected to the 100 nm ITO via a relay layer 39 also made of a 500 nm Al (aluminum) thin film. The pixel electrode 24 which is (indium tin oxcide) is electrically connected. Further, a reflective electrode 35, which is a 200 nm Al thin film, is disposed under a part of the pixel electrode 24 so as to function as a transflective liquid crystal display device. The gate electrode 31, the source electrode 32, and the drain electrode 33 are an insulating layer 34c made of a silicon oxide film having a thickness of 500 nm, and the source electrode 32, the drain electrode 33, and the pixel electrode 24 are an acrylic organic flattening having an average thickness of 1 μm. Each is electrically isolated by an insulating layer 34d made of a film.

  Further, in order to realize color display of the liquid crystal display device on the lower surface portion of the counter substrate 3, the display area for displaying an image passes through only a specific wavelength range of transmitted light, thereby allowing red, green, and blue colors. A color material 38 (color filter) for realizing display and a black matrix layer 37 for preventing light leakage and improving contrast in a display area for displaying an image are provided. The black matrix layer 37 is made of a black resin having a thickness of 1 μm, and is formed in a portion facing the pixel switching element 23. The black matrix layer 37 blocks external light to reduce leakage of the pixel switching element 23, and This prevents the decrease in contrast due to light leakage and reflection. On the other hand, the color material 38 is made of a color resist of any of the three primary colors (red, green, and blue) corresponding to the pixel, and is formed in a portion facing the pixel electrode 24 and the reflective electrode 35. Further, on the lower surfaces of the black matrix layer 37 and the color material 38, a counter electrode 25 made of 100 nm ITO is formed so as to cover all the pixel electrodes 24 including other pixel electrodes (not shown).

On the other hand, the first and second photosensors 21 and 22 provided on the active matrix substrate 2 are photosensors each composed of a field effect diode.
In the first photosensor 21, a source electrode 41a and a drain electrode 42a are respectively disposed on both sides of a channel portion 40a, a source power supply wiring 43a is connected to the source electrode 41a, and a drain power supply wiring 44a is connected to the drain electrode 42a. Further, the gate electrode 45a is disposed above the channel portion 40a. An insulating film 46b is interposed between the channel portion 40a and the gate electrode 45a. Further, the first photosensor 21 has a gate electrode 45a and a source electrode 41a that are short-circuited, and functions as a diode of a two-terminal element.
The second photosensor 22 has the same configuration as the first photosensor 21 described above. A source electrode 41b and a drain electrode 42b are provided on both sides of the channel portion 40b, and a source power supply line 43b is provided on the source electrode 41b. The drain power supply wiring 44b is connected to the drain electrode 42b, and the gate electrode 45b is disposed above the channel portion 40b. An insulating film 46b is interposed between the channel portion 40b and the gate electrode 45b. Further, the second photosensor 22 is the same as the first photosensor 21 in that the gate electrode 45b and the source electrode 41b are short-circuited and function as a diode of a two-terminal element.

Here, the channel portions 40 a and 40 b of the first and second photosensors 21 and 22 have the same film thickness and the same film as the channel portion 30 made of an intrinsic polycrystalline thin film silicon thin film that constitutes the pixel switching element 23. It is made of a constituent material and is manufactured in the same manufacturing process as that of the channel part 30. Thereby, the manufacturing process can be shortened and the cost can be reduced.
The source electrodes 41 a and 41 b and the drain electrodes 42 a and 42 b of the first and second photosensors 21 and 22 are the same as the source electrode 32 and the drain electrode 33 made of n + thin film silicon constituting the pixel switching element 23. The source electrode 32 and the drain electrode 33 are manufactured in the same manufacturing process. Thereby, the manufacturing process can be shortened and the cost can be reduced.
Further, the gate electrodes 45 a and 45 b of the first and second photosensors 21 and 22 are formed of the same film thickness and the same film constituent material as the gate electrode 31 of the Cr thin film 300 nm constituting the pixel switching element 23. The gate electrode 31 is manufactured in the same manufacturing process. Thereby, the manufacturing process can be shortened and the cost can be reduced.
The source power supply wirings 43a and 43b and the drain power supply wirings 44a and 44b of the first and second photosensors 21 and 22 have the same film thickness and the same film as the data line 16 and the relay layer 39 of the Al thin film 500 nm. The data line 16 and the relay layer 39 are manufactured in the same manufacturing process. Thereby, the manufacturing process can be shortened and the cost can be reduced.
Further, the insulating film 46b interposed between the channel portions 40a and 40b of the first and second photosensors 21 and 22 and the gate electrodes 45a and 45b is connected to the channel portion 30 and the gate electrode 31 of the pixel switching element 23. The insulating film 34b with 50 nm of silicon oxide interposed between them is formed of the same film thickness and the same film constituent material, and is manufactured in the same manufacturing process as the insulating film 34b. Thereby, the manufacturing process can be shortened and the cost can be reduced.

  In addition, an external light shielding film 28 disposed in a region overlapping the second photosensor 22 is provided on the upper side (outside) of the counter substrate 3. The external light shielding film 28 is bonded to the outer surface (upper surface) of the upper polarizing plate 6. The external light shielding film 28 is integrally formed as a part of a metal housing (not shown) of the liquid crystal display device, and thus the cost can be reduced. The external light shielding film 28 may be a light shielding tape, for example.

  As a method for measuring the light applied to the first photosensor 21 having the above-described configuration, for example, 0 V (GND) is applied to the source power supply wiring 43 and +5 V is applied to the drain power supply wiring 44, respectively. What is necessary is just to measure the electric current which flows between the source power supply wiring 43 and the drain power supply wiring 44. FIG. The same applies to the case where the light applied to the second photosensor 22 is measured.

As a matter of course, the first and second photosensors 21 and 22 may be formed of p-channel thin film diodes without using n-channel thin film diodes as the first and second photosensors 21 and 22. .
Further, the first and second photosensors 21 and 22 may be manufactured with a channel type different from that of the pixel switching element 23. In this case, the manufacturing process is different only in the doping process. In any case, it is preferable that the active layers (in this case, the channel portions 30, 40 a, 40 b), which are particularly expensive to manufacture, are formed of the same film thickness and the same film constituent material and manufactured in the same manufacturing process.

Next, a second specific example of the liquid crystal display device according to the first embodiment will be described.
FIG. 7 is an enlarged cross-sectional view showing a second specific example of the liquid crystal display device according to the first embodiment.
As shown in FIG. 7, the configuration on the pixel switching element 23 side (left side in FIG. 7) in the second specific example is the same as the configuration on the pixel switching element 23 side (left side in FIG. 6) in the first specific example described above. Since they are the same, the description thereof is omitted by giving the same reference numerals, and only the configuration on the first and second photosensors 21 and 22 side (right side in FIG. 7) in the second specific example will be described below. .

The first and second photosensors 21 and 22 are photosensors each composed of a PIN junction diode.
In the first photosensor 21, an n + type region 48a made of n + thin film silicon and a p + type region 49a made of p + thin film silicon are respectively disposed on both sides of an intrinsic semiconductor portion 47a made of a polycrystalline thin film silicon thin film. The cathode power wiring 50a is connected to 48a, and the anode power wiring 51a is connected to the p + type region 49a.
The second photosensor 22 has the same configuration as the first photosensor 21 made of the above-described PIN junction type diode, and n + type regions made of n + thin film silicon on both sides of the intrinsic semiconductor portion 47b made of a polycrystalline thin film silicon thin film. The p + type region 49b made of 48b and p + thin film silicon is disposed, the cathode power supply wiring 50b is connected to the n + type region 48b, and the anode power supply wiring 51b is connected to the p + type region 49b.

Here, the intrinsic semiconductor portions 47 a and 47 b of the first and second photosensors 21 and 22 have the same film thickness and the same thickness as the channel portion 30 made of the intrinsic polycrystalline thin-film silicon thin film constituting the pixel switching element 23. It is made of a film constituent material and is manufactured in the same manufacturing process as that of the channel part 30. Thereby, the manufacturing process can be shortened and the cost can be reduced.
The n + -type regions 48 a and 48 b of the first and second photosensors 21 and 22 have the same film thickness and the same thickness as the source electrode 32 and the drain electrode 33 made of n + thin film silicon constituting the pixel switching element 23. It is made of a film constituent material and is manufactured in the same manufacturing process as the source electrode 32 and the drain electrode 33. Thereby, the manufacturing process can be shortened and the cost can be reduced.
The cathode power supply lines 50a and 50b and the anode power supply lines 51a and 51b of the first and second photosensors 21 and 22 are formed of the same film thickness and the same film constituent material as the data line 16 and the relay layer 39. The data line 16 and the relay layer 39 are manufactured in the same manufacturing process. Thereby, the manufacturing process can be shortened and the cost can be reduced.

  In addition, an external light shielding film 28 disposed in a region overlapping the second photosensor 22 is interposed between the active matrix substrate 2 and the liquid crystal material 4. The external light shielding film 28 is embedded in the upper part of the active matrix substrate 2 and is in contact with the lower surface of the liquid crystal material 4. The external light shielding film 28 is formed of the same film thickness and the same film constituent material as the reflective electrode 35 of the Al thin film 200 nm, and is manufactured in the same manufacturing process as the reflective electrode 35. Thereby, the manufacturing process can be shortened and the cost can be reduced.

Next, a third specific example of the liquid crystal display device according to the first embodiment will be described.
FIG. 8 is an enlarged cross-sectional view showing a third specific example of the liquid crystal display device according to the first embodiment.
As shown in FIG. 8, the configuration on the pixel switching element 23 side (left side in FIG. 8) in the third specific example is the same as that on the pixel switching element 23 side in the first and second specific examples (FIGS. 6 and 7). The description is omitted by giving the same reference numerals. Further, the first and second photosensors 21 and 22 in the third specific example are photosensors configured by PIN junction type diodes as in the second specific example, and the first and second photosensors. Since the configuration of 21 and 22 itself is the same as that of the second specific example, the description thereof is omitted by attaching the same reference numerals. Only the configuration of the external light shielding film 28 in the third specific example will be described below.

  The external light shielding film 28 includes a first external light shielding film 52 interposed between the liquid crystal material 4 and the counter substrate 3, and a second outer light embedded in the insulating layers 46 a to 46 d of the active matrix substrate 2. The light-shielding film 53 has a double structure, and the first and second external light-shielding films 52 and 53 are respectively disposed in regions overlapping with the second photosensor 22.

The first external light shielding film 52 is embedded in the upper part of the liquid crystal material 4 and is in contact with the lower surface of the counter substrate 3. Here, the first external light shielding film 52 is formed of the same film constituent material as that of at least one of the color materials 38 and is manufactured in the same manufacturing process, and preferably a color corresponding to red display. Of the thin film made of the same film constituent material as the material 38, the thin film made of the same film constituent material as the color material 38 corresponding to blue display, or the thin film made of the same film constituent material as the color material 38 corresponding to green display In this structure, at least two kinds of coating films are stacked, thereby making it possible to shorten the manufacturing process and reduce the cost, improve the light shielding property of the outside light shielding film 28, and accurately adjust the outside light illuminance LA. It can be detected well. For example, the first external light shielding film 52 is formed by stacking a thin film made of the same material as the color material 38 corresponding to red and a thin film made of the same material as the color material 38 corresponding to green in order to improve the light shielding property. The red / green two-layer structure. Of course, the same material as the other color material 38 corresponding to, for example, blue may be used, or the same three kinds of film constituent materials as the red, green, and blue color materials 38 may be stacked. Further, the same film constituent material (resin) as the black matrix 37 may be stacked. In general, the light-shielding property increases as the layers are stacked, but if the layers are stacked too much, the film thickness becomes too thick, and problems such as stepping and film peeling are likely to occur.
In this embodiment, the color material 38 and the black matrix layer 37 are arranged on the counter substrate 3. However, the color material 38 and the black matrix layer 37 are arranged on the active matrix substrate 2. A filter on array structure or a black matrix on array structure may be used. In this case, the first external light shielding film 52 is also preferably formed on the active matrix substrate 2 in the same process.

  The second external light shielding film 53 is disposed above the intrinsic semiconductor portion 47 b of the second photosensor 22 with a space therebetween. The second external light shielding film 53 is a thin film manufactured in the same manufacturing process as the data line 16 and the relay layer 39 and has the same film thickness and composition as the data line 16 and the relay layer 39. . Thereby, the manufacturing process can be shortened and the cost can be reduced. Of course, it may be a film manufactured by the same material and the same process as the reflective electrode 35 and the gate electrode 31 of the pixel switching element 23, or a plurality of these films may be superposed, thereby shortening the manufacturing process and reducing the cost. Can be planned.

Next, a fourth specific example of the liquid crystal display device in the first embodiment will be described.
FIG. 9 is an enlarged cross-sectional view illustrating a fourth specific example of the liquid crystal display device according to the first embodiment.
As shown in FIG. 9, the configuration on the pixel switching element 23 side (left side in FIG. 8) in the fourth specific example is the pixel switching element 23 side (FIG. 6) in the first, second, and third specific examples described above. , FIGS. 7 and 8 are the same as those in the left side in FIG. Further, the first and second photosensors 21 and 22 in the fourth specific example are photosensors configured by PIN junction type diodes as in the second and third specific examples described above. Since the configuration of the photosensors 21 and 22 themselves is the same as that of the second and third specific examples, the description thereof is omitted by giving the same reference numerals. Only the configuration of the external light shielding film 28 in the fourth specific example will be described below.

The external light shielding film 28 is interposed between the active matrix substrate 2 and the counter substrate 3, and is disposed in a region overlapping the second photosensor 22. The external light shielding film 28 is formed of the same film constituent material as the sealing material 5 that joins the active matrix substrate 2 and the counter substrate 3, and is manufactured in the same manufacturing process as the sealing material 5. Thereby, the manufacturing process can be shortened and the cost can be reduced. At this time, it is preferable to mix a black pigment or the like with the sealing material 5 (external light shielding film 28) to obtain the external light shielding film 28 having high light shielding properties.
In each specific example of the first embodiment, it is preferable that the first photosensor 21 and the second photosensor 22 are evenly irradiated with the backlight light B. Therefore, it is preferable to arrange both the first photosensor 21 and the second photosensor 22 in the vicinity of the display area, for example, in the dummy pixel area.
Further, as another embodiment, the backlight 8 may not be provided in the overlapping region or may be placed in a region that is not irradiated by the backlight 8. For example, if the first photosensor 21 and the second photosensor 22 are arranged in the overhanging portion 2a, both irradiation light from the backlight light B can be handled as almost zero.

[Second Embodiment]
Next, a schematic configuration for measuring external light illuminance in the second embodiment will be described.
FIG. 10 is a schematic diagram showing a configuration for measuring the illuminance of external light in the second embodiment.
As shown in FIG. 10, the first photosensor 21 of the two photosensors 21 and 22 respectively disposed on the active matrix substrate 2 (shown in FIG. 2) is irradiated with external light A. At the same time, the backlight light B is blocked by the backlight light-shielding film 60 (illumination light shielding part). In the second photosensor 22, the external light A is blocked by the external light-shielding film 28. At the same time, the backlight light B is irradiated.

  In the configuration as described above, the current I1 (output value) flowing through the first photosensor 21 and the current I2 (output value) flowing through the second photosensor 22 are respectively expressed by the following equations. Here, LA is the illuminance of the external light A on the first photosensor 21, LB is the illuminance of the backlight light B irradiated on the second photosensor 22, and Vd1 is the first photosensor. The voltage between the anode and the cathode of the diode constituting the sensor 21, Vgs 1 is the voltage between the gate and the source of the transistor constituting the first photosensor 21, and Vds1 is the drain of the transistor constituting the first photosensor 21. The source voltage, temp1 is the absolute temperature of the first photosensor 21, Vd2 is the anode-cathode voltage of the diode constituting the second photosensor 22, and Vgs2 is the second photosensor 22. Vds2 is a voltage between the gate and the source of the transistor that constitutes the second photosensor 22. A between-in source voltage, temp2 is the absolute temperature of the second photosensor 22. The first photosensor 21 and the second photosensor 22 have the same device structure except for the light shielding state, and the same current flows under the same conditions.

Here, when the same bias voltage is applied to the first photosensor 21 and the second photosensor 22, Vd1 = Vd2 = Vd, Vgs1 = Vgs2 = Vgs, and Vds1 = Vds2 = Vds. Specifically, for example, Vd = -4V, Vgs = -5V, Vds = -4V, and the like. In addition, since the first photosensor 21 and the second photosensor 22 are arranged on the same substrate active matrix substrate 2, temp1 = temp = temp because the temperatures can be equal. If the circuit is configured so that Vd, Vgs, and Vds are constant, Iphoto ′ (Vd) and Iphoto ′ (Vgs, Vds) can also be handled as constants (hereinafter simply referred to as Iphoto ′).
From the above equation and assumption, the difference (I1−I2) between the current I1 flowing through the first photosensor 21 and the current I2 flowing through the second photosensor 22 is expressed by the following equation.

Since the currents I ₁ and I ₂ in the above formula are output from the first and second photosensors 21 and 22, respectively, if this is measured, the external light illuminance LA is calculated from the above formula. The calculated external light illuminance LA is an accurate value considering heat leak, and the control signal sent to the backlight unit 8 is corrected based on the external light illuminance LA. Thereby, the control signal corrected by the temperature can be sent to the backlight unit 8, and the illuminance control of the backlight unit 8 can be performed more accurately than before, and the visibility can be improved. Can do.
Further, the backlight unit 8 is operated to change the illuminance of the backlight light B from the first illuminance LB1 to the second illuminance LB2, and the current I21 flowing through the second photosensor 22 at the first illuminance LB1. Is the same as in the first embodiment in that Iphoto ′ can be calibrated by measuring the current I22 flowing through the second photosensor 22 at the time of the second illuminance LB2.

  The backlight control unit 12 is provided with means for detecting whether the external light illuminance LA is larger or smaller than a specific value. Specifically, the backlight illuminance LB is set to a specific value (target illuminance). Then, the output value I1 of the first photosensor 21 and the output value I2 of the second photosensor 22 are respectively measured, and the external light illuminance LX (A) with respect to the specific value from the difference (I1−I2) between these output values. Detect the size of. That is, if it is determined whether the difference (I1−I2) between the output values is 0 or more or 0 or less, it is detected whether the external light illuminance LA is larger or smaller than the specific value. When such a detection method is used, there is no need to perform analog-to-digital conversion of the current, and only the magnitude of the current needs to be compared. Therefore, the circuit becomes simpler and the comparison can be performed accurately.

  According to the above-described detection means, for example, as shown in FIG. 3, when the backlight unit 8 is controlled to be turned off when the external light illuminance LA becomes a certain value or more, the backlight unit 8 is turned off. The illuminance to be performed is set as a specific value, and the backlight illuminance LB is set to the constant value. Then, when the output value difference (I1-I2) becomes 0, the backlight unit 8 is turned off. Thereby, the control accuracy of the backlight unit 8 can be improved.

  In addition, as a method of detecting the external light illuminance LA by the above-described detection means, for example, first, a specific value is set to an expected value (can be any value) of the external light illuminance LA, and the first and second photo The sensors 21 and 22 output currents I1 and I2, respectively, and determine whether the difference (I1-I2) between the output values is 0 or more and 0 or less. If the output value difference (I1-I2) is greater than or equal to 0, the specific value is increased, and the currents I1 and I2 are output again by the first and second photosensors 21 and 22, respectively. It is determined whether (I1-I2) is 0 or more and 0 or less. On the other hand, if the output value difference (I1-I2) is 0 or less, the specific value is lowered, and the currents I1 and I2 are output again by the first and second photosensors 21 and 22, respectively. It is determined whether (I1-I2) is 0 or more and 0 or less. The above steps are repeated until the output value difference (I1-I2) becomes zero, and the specific value when the output value difference (I1-I2) becomes zero becomes the external light illuminance. Thereby, the detection accuracy of the external light illuminance LA can be improved.

  Next, a specific configuration of the liquid crystal display device according to the second embodiment will be described below with reference to first and second specific examples.

First, a first specific example of the liquid crystal display device according to the second embodiment will be described.
FIG. 11 is an enlarged cross-sectional view showing a first specific example of the liquid crystal display device according to the second embodiment.
The configuration on the pixel switching element 23 side (left side in FIG. 11) in the first specific example of the second embodiment is the same as that of the first to fourth specific examples of the first embodiment described above. Since the configuration is the same as that on the pixel switching element 23 side (the left side in FIGS. 6, 7, 8, and 9), the same reference numerals are used to omit the description, and the second embodiment will be described below. Only the configuration on the first and second photosensors 21 and 22 side (right side in FIG. 11) in the first specific example will be described.

  As shown in FIG. 11, the first and second photosensors 21 and 22 are photosensors each composed of an n-channel transistor. The first and second photosensors 21 and 22 are different from the first and second photosensors 21 and 22 made of the field effect diode described in the first specific example of the first embodiment. The electrodes 45a and 45b and the source electrodes 41a and 41b are not short-circuited but separated. Other configurations are the same as those of the first and second photosensors 21 and 22 made of field-effect diodes, and the description thereof is omitted by giving the same reference numerals.

  In addition, an external light shielding film 28 disposed in a region overlapping the second photosensor 22 is interposed between the liquid crystal material 4 and the counter substrate 3. The external light shielding film 28 is embedded in the upper part of the liquid crystal material 4 and is in contact with the lower surface of the counter substrate 3. The external light shielding film 28 is made of a black resin formed in the same manufacturing process as the black matrix 37. Thereby, the manufacturing process can be shortened and the cost can be reduced. In this embodiment, the configuration in which the black matrix layer 37 is provided on the counter substrate 3 has been described. However, a so-called black matrix on-array structure in which the black matrix layer 37 is provided on the active matrix substrate 2 may be used. In this case, the first external light shielding film 52 is also preferably formed on the active matrix substrate 2 in the same process.

  In addition, on the outside (lower side) of the active matrix substrate 2, a backlight light shielding film 60 disposed in a region overlapping the first photosensor 21 is provided. The backlight light shielding film 60 is bonded to the outer surface (lower surface) of the lower polarizing plate 7. Further, the backlight light-shielding film 60 is formed by projecting a metal plate, which is an exterior of the backlight unit 8, under the first photosensor 21. Alternatively, for example, a light shielding tape may be attached or an exterior frame of a liquid crystal display device may be used.

  As a method for measuring the light applied to the first photosensor 21 having the above-described configuration, for example, -5V is applied to the gate electrode 45a, 0V (GND) is applied to the source power supply wiring 43a, and + 5V is applied to the drain power supply wiring 44a. What is necessary is just to measure the electric current which flows between the source power supply wiring 43a and the drain power supply wiring 44a at this time, respectively. The same applies to the case where the light applied to the second photosensor 22 is measured.

As a matter of course, the first and second photosensors 21 and 22 may be formed of p-channel thin film transistors without using n-channel thin film transistors as the first and second photosensors 21 and 22. In this case, as a method for measuring the light applied to the first photosensor 21, for example, + 5V is applied to the gate electrode 45a, 0V (GND) is applied to the source power supply wiring 43a, and −5V is applied to the drain power supply wiring 44a. At this time, the current flowing between the source power supply wiring 43a and the drain power supply wiring 44a may be measured. The same applies to the case where the light applied to the second photosensor 22 is measured.
Further, the first and second photosensors 21 and 22 may be manufactured with a channel type different from that of the pixel switching element 23. In this case, the manufacturing process is different only in the doping process. In any case, it is preferable that the active layers (in this case, the channel portions 30, 40 a, 40 b), which are particularly expensive to manufacture, are formed of the same film thickness and the same film constituent material and manufactured in the same manufacturing process.

Next, a second specific example of the liquid crystal display device according to the second embodiment will be described.
FIG. 12 is an enlarged cross-sectional view showing a second specific example of the liquid crystal display device according to the second embodiment.

  As shown in FIG. 12, the pixel switching element 23 provided on the active matrix substrate 2 is a bottom gate type transistor, and a bottom gate electrode 31 ′ made of a Cr thin film with a thickness of 150 nm is provided below the channel portion 30. It is the composition provided in. That is, other configurations on the pixel switching element 23 side (left side in FIG. 12) are the first to fourth specific examples of the first embodiment described above and the first configuration of the second embodiment. Compared with the configuration on the pixel switching element 23 side (left side in FIGS. 6, 7, 8, 9, and 11) in the specific example, the bottom gate electrode 31 ′ as a gate electrode is a base material of the active matrix substrate 2. 58 is different from the channel portion 30 of the pixel switching element 23 in the other respects, and the other configurations are the same.

  The first and second photosensors 21 and 22 provided on the active matrix substrate 2 have the same configuration as that of the second to fourth specific examples of the first embodiment described above, and each has a PIN. It is a photosensor composed of a junction diode. About a concrete structure, the description is abbreviate | omitted by attaching | subjecting the same code | symbol as the 2nd-4th specific example about 1st Embodiment.

In the insulating films 46a to 46e on the first and second photosensors 21 and 22 side (the right side in FIG. 12), a backlight light-shielding film 60 disposed in a region overlapping the first photosensor 21, and the first An external light shielding film 28 disposed in a region overlapping the two photosensors 22 is embedded. The backlight light-shielding film 60 is disposed below the intrinsic semiconductor portion 47a of the first photosensor 21, and is formed with the same film thickness and the same film constituent material as the bottom gate electrode 31 'of the pixel switching element 23. In the same manufacturing process as that of the bottom gate electrode 31 '. Thereby, the manufacturing process can be shortened and the cost can be reduced. The external light shielding film 28 is disposed above the intrinsic semiconductor portion 47b of the second photosensor 22, and has the same thickness and the same thickness as the data line 16 and the relay layer 39 of the pixel switching element 23. The data line 16 and the relay layer 39 are manufactured in the same manufacturing process. Thereby, the manufacturing process can be shortened and the cost can be reduced. The external light shielding film 28 may be manufactured in the same film constituent material and the same manufacturing process as the reflective electrode 35 of the pixel switching element 23, or a plurality of these may be superposed, thereby producing a manufacturing process. The cost can be reduced by shortening.
In each specific example of the second embodiment, it is preferable that the second photosensor 22 is equally irradiated with the backlight light B, and the second photosensor 22 is in the vicinity of the display region, for example, a dummy pixel region. It is preferable to arrange in the above.
The first photosensor 21 may be placed in a region where the backlight 8 is not present or not illuminated by the backlight 8. For example, it is more preferable if the first photosensor 21 is disposed in the overhang portion 2a.

[Third Embodiment]
Next, a schematic configuration for measuring external light illuminance in the third embodiment will be described.
FIG. 13 is a schematic diagram showing a configuration for measuring the illuminance of external light in the third embodiment.
As shown in FIG. 13, of the two photosensors 21 and 22 arranged on the active matrix substrate 2 (shown in FIG. 2), the first photosensor 21 is irradiated with external light A. At the same time, the backlight light B is blocked by the first backlight blocking film 61 (illumination light blocking section), and the second photosensor 22 blocks the outside light A by the outside light blocking film 28. In addition, the backlight light B is blocked by the second backlight light blocking film 62 (illumination light blocking portion).

  In the configuration as described above, the current I1 (output value) flowing through the first photosensor 21 and the current I2 (output value) flowing through the second photosensor 22 are respectively expressed by the following equations. Here, LA is the illuminance of outside light A on the first photosensor 21, Vd1 is the anode-cathode voltage of the diode constituting the first photosensor 21, and Vgs1 is the first photosensor. Vds1 is the drain-source voltage of the transistor constituting the first photosensor 21, temp1 is the absolute temperature of the first photosensor 21, and Vd2 Is the anode-cathode voltage of the diode that constitutes the second photosensor 22, Vgs2 is the gate-source voltage of the transistor that constitutes the second photosensor 22, and Vds2 is the voltage across the second photosensor 22. This is the voltage between the drain and source of the transistor to be configured, and temp2 is the absolute temperature of the second photosensor 22The first photosensor 21 and the second photosensor 22 have the same device structure except for the light shielding state, and the same current flows under the same conditions.

Here, when the same bias voltage is applied to the first photosensor 21 and the second photosensor 22, Vd1 = Vd2 = Vd, Vgs1 = Vgs2 = Vgs, and Vds1 = Vds2 = Vds. Specifically, for example, Vd = -4V, Vgs = -5V, Vds = -4V, and the like. In addition, since the first photosensor 21 and the second photosensor 22 are arranged on the same substrate active matrix substrate 2, temp1 = temp = temp because the temperatures can be equal. If the circuit is configured so that Vd, Vgs, and Vds are constant, Iphoto ′ (Vd) and Iphoto ′ (Vgs, Vds) can also be handled as constants (hereinafter simply referred to as Iphoto ′).
From the above equation and assumption, the difference (I1−I2) between the current I1 flowing through the first photosensor 21 and the current I2 flowing through the second photosensor 22 is expressed by the following equation.

Since the currents I1 and I2 in the above formula are output from the first and second photosensors 21 and 22, respectively, if this is measured, the external light illuminance LA is calculated from the above formula. The calculated external light illuminance LA is an accurate value considering heat leak, and the control signal sent to the backlight unit 8 is corrected based on the external light illuminance LA. Thereby, the control signal corrected by the temperature can be sent to the backlight unit 8, and the illuminance control of the backlight unit 8 can be performed more accurately than before, and the visibility can be improved. Can do. Although this method cannot cope with individual variations of Iphoto ′ for each product, it is expected that Iphoto ′ of both photosensors 21 and 22 will vary, and the second photosensor 22 to the first photosensor 21 a. If it is difficult to analogize, only the temperature leak may be excluded by this method.
Further, in this method, the installation location of the second photosensor 22 may not be a location where the backlight light B or the outside light A can be irradiated, and there is an advantage that it is relatively free. For example, the overhanging portion 2a.

  Next, a specific configuration of the liquid crystal display device according to the third embodiment will be described.

FIG. 14 is an enlarged cross-sectional view showing a specific example of the liquid crystal display device according to the third embodiment.
As shown in FIG. 14, the pixel switching element 23 is a top-gate transistor, and a light shielding film 63 (transistor light shielding) made of a Cr film 150 nm is provided between the channel portion 30 of the pixel switching element 23 and the backlight unit 8. Layer) is provided to suppress an increase in leakage of the pixel switching element 23 due to the backlight light B. The light shielding film 63 is embedded in the insulating layers 34a to 34e on the pixel switching element 23 side (left side in FIG. 14), and although not shown, the light shielding films 63 facing the pixel switching elements 23 are mutually connected. Short-circuited to a housing GND (not shown) or a common common potential.
The other configurations on the pixel switching element 23 side (left side in FIG. 14) in the specific example of the third embodiment are the first to fourth specific examples of the first embodiment described above, And since it is the same as that of the structure of the pixel switching element 23 in the 1st specific example about 2nd Embodiment, the description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  On the other hand, the first and second photosensors 21 and 22 provided on the active matrix substrate 2 are the second to fourth specific examples of the first embodiment described above and the second embodiment. This is a photosensor having a configuration similar to that of the second specific example regarding the form, and each including a PIN junction diode. About a concrete structure, the 2nd-4th specific example about 1st Embodiment and the 2nd specific example about 2nd Embodiment are attached | subjected, and the description is abbreviate | omitted.

  In the insulating films 46 a to 46 e on the first and second photosensors 21 and 22 side (right side in FIG. 14), a first backlight light shielding film 61 disposed in a region overlapping with the first photosensor 21. And an external light shielding film 28 disposed in a region overlapping with the second photosensor 22 and a second backlight shielding film 62 disposed in a region overlapping with the second photosensor 22 are embedded. ing. The first backlight light-shielding film 61 is disposed below the intrinsic semiconductor portion 47 a of the first photosensor 21, and the second backlight light-shielding film 62 is an intrinsic semiconductor portion of the second photosensor 22. The first and second backlight light shielding films 61 and 62 are formed with the same film thickness and the same film constituent material as the light shielding film 63 on the pixel switching element 23 side. It is manufactured in the same manufacturing process as the light shielding film 63. The external light shielding film 28 is disposed above the intrinsic semiconductor portion 47b of the second photosensor 22, and has the same film thickness and the same film constituent material as the gate electrode 31 of the pixel switching element 23. The gate electrode 31 is formed in the same manufacturing process. The external light shielding film 28 may be manufactured by the same film constituent material and the same manufacturing process as the data line 16, the relay layer 39, the reflective electrode 35, the black matrix 37, and the color material 38. A plurality may be overlapped.

Further, in the above-described specific example, the light shielding film 63 is short-circuited and used as light shielding. However, the light shielding film 63 is electrically separated and driven individually, thereby acting as a back gate. In this case, the pixel switching element 23 is configured as a so-called four-terminal transistor.
In the specific example of the third embodiment, the first photosensor 21 and the second photosensor 22 are evenly irradiated with the backlight light B, or more preferably both in areas not irradiated with the backlight 8. It is desirable that they are arranged. Accordingly, both the first photosensor 21 and the second photosensor 22 are arranged in the vicinity of the display area, for example, in the dummy pixel area, or more preferably, for example, in the overhanging portion 2a. A photo sensor 22 may be disposed.
Further, in common with the first to third embodiments, it is preferable to arrange the first photosensor 21 and the second photosensor 22 so that the characteristics, that is, Iphoto ′ and Ithermal are as close as possible. Specifically, it is desirable to arrange the first photosensor 21 and the second photosensor 22 as close as possible. The first photosensor 21 and the second photosensor 22 are preferably designed to have the same shape. Further, when the first photosensor 21 and the second photosensor 22 are arranged, it is not preferable to arrange them by rotating or reversing. Further, when the intrinsic polycrystalline silicon thin film constituting the first photosensor 21 and the second photosensor 22 is formed by laser annealing, the first photosensor 21 and the second photosensor 22 are formed with the same laser shot. It is preferable to arrange so that the intrinsic polycrystalline silicon thin film to be formed is formed.

  The first to third embodiments of the liquid crystal display device according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. It is. For example, as shown in FIG. 15, the first photosensor 121 is in a state where the external light A and the backlight light B are respectively irradiated, and the second photosensor 122 is configured so that the external light A is external light. The backlight light B may be blocked by the light blocking unit 128 and the illumination light blocking unit 160. In addition, the code | symbol 112 shown in FIG. 15 is a backlight control unit which controls the backlight unit 108. FIG.

  In the configuration as described above, the current I1 (output value) flowing through the first photosensor 121 and the current I2 (output value) flowing through the second photosensor 122 are each expressed by the following equations. Here, LA is the illuminance of outside light A on the first photosensor 21, Vd1 is the anode-cathode voltage of the diode constituting the first photosensor 21, and Vgs1 is the first photosensor. Vds1 is the drain-source voltage of the transistor constituting the first photosensor 21, temp1 is the absolute temperature of the first photosensor 21, and Vd2 Is the anode-cathode voltage of the diode that constitutes the second photosensor 22, Vgs2 is the gate-source voltage of the transistor that constitutes the second photosensor 22, and Vds2 is the voltage across the second photosensor 22. This is the voltage between the drain and source of the transistor to be configured, and temp2 is the absolute temperature of the second photosensor 22The first photosensor 21 and the second photosensor 22 have the same device structure except for the light shielding state, and the same current flows under the same conditions.

Here, when the same bias voltage is applied to the first photosensor 21 and the second photosensor 22, Vd1 = Vd2 = Vd, Vgs1 = Vgs2 = Vgs, and Vds1 = Vds2 = Vds. Specifically, for example, Vd = -4V, Vgs = -5V, Vds = -4V, and the like. In addition, since the first photosensor 21 and the second photosensor 22 are arranged on the same substrate active matrix substrate 2, temp1 = temp = temp because the temperatures can be equal. If the circuit is configured so that Vd, Vgs, and Vds are constant, Iphoto ′ (Vd) and Iphoto ′ (Vgs, Vds) can also be handled as constants (hereinafter simply referred to as Iphoto ′).
From the above formula and assumption, the difference (I1−I2) between the current I1 flowing through the first photosensor 121 and the current I2 flowing through the second photosensor 122 is expressed by the following formula.

  The currents I1 and I2 in the above equation are respectively output from the first and second photosensors 21 and 22, and the LB is known. If this is measured, the external light illuminance LA is calculated from the above equation. . The calculated external light illuminance LA is an accurate value considering heat leak, and the control signal sent to the backlight unit 8 is corrected based on the external light illuminance LA. Thereby, the control signal corrected by the temperature can be sent to the backlight unit 8, and the illuminance control of the backlight unit 8 can be performed more accurately than before, and the visibility can be improved. Can do.

  In the first to third embodiments described above, the first and second photosensors 21 and 22 are photosensors having the same configuration. However, the present invention provides the first and second photosensors. The photo sensor which consists of a different structure may be sufficient as a photo sensor.

  In the first to third embodiments described above, the external light shielding film 28 and the backlight shielding film 60 (including the first and second backlight shielding films 61 and 62) are each formed in a thin film shape. Although formed, the external light shielding part and the illumination light shielding part do not have to be in the form of a thin film. For example, a plate-shaped external light shielding part and an illumination light shielding part may be used. In the first to third embodiments described above, the external light shielding film 28 and the backlight shielding film 60 (including the first and second backlight shielding films 61 and 62) are also provided in the liquid crystal module 1. Or is attached to the surface of the liquid crystal module 1, that is, the external light shielding film 28 and the backlight shielding film 60 are part of the liquid crystal module 1. The light shielding part and the illumination light shielding part may be parts separated from the liquid crystal panel.

In the present invention, for example, the pixel switching element (active element) may be a thin film amorphous silicon transistor (aSi-TFT). In this case, thin film amorphous silicon is used as the active layer of the first and second photosensors. Use it. Similarly, for example, the pixel switching element (active element) may be a thin film diode (TFD) or a single crystal silicon transistor.
In the first to third embodiments described above, a TN (twisted nematic) mode or VA (vertically aligned) mode liquid crystal display device having a counter electrode on the counter substrate 3 (second substrate) is assumed. However, the present invention may be an IPS (in-plane switching) mode having a counter electrode on an active matrix substrate (first substrate), and can be applied to any other transmissive / semi-transmissive liquid crystal display device. There is no problem.

In the first to third embodiments described above, the first and second photosensors 21 and 22 are provided on the active matrix substrate 2 (first substrate). 3 (second substrate) may be provided with first and second photosensors.
In the first to third embodiments described above, the substrate (first substrate) on the side facing the backlight unit 8 and irradiated with the backlight light is the active matrix substrate. The opposite substrate (second substrate) may be an active matrix substrate.
In the first to third embodiments, the black matrix (black matrix layer) 37 and the color material (color filter layer) are provided only on the surface of the counter substrate 3 (second substrate) on the liquid crystal material 4 side. In the present invention, a black matrix layer or a color filter layer may be provided on the surface of the active matrix substrate (first substrate) on the liquid crystal side, or a black matrix layer or a color filter layer may be provided on both substrates. A color filter layer may be provided.
In addition, the combinations shown in the specific examples of the first to third embodiments described above can be changed as appropriate without departing from the gist of the present invention. It is also possible to replace with the configuration of

  Next, an electronic apparatus according to the present invention will be described.

FIG. 16 is a perspective view illustrating an electronic device, and FIG. 17 is a block diagram illustrating a configuration of the electronic device.
As shown in FIG. 16, the liquid crystal display device 200 having the above-described configuration is used as a display unit 70a of a mobile phone 70, and is a display device including the liquid crystal module 1 having the above-described configuration. As shown in FIG. 17, the electronic device includes an LCD (liquid crystal display) module 200 (liquid crystal display device), a display information processing circuit 201 that controls the module, a central processing circuit 202, an external I / F circuit 203, and an input / output. A device 204 and a power supply circuit 205 are included.

  The display information processing circuit 201 appropriately rewrites video data stored in a RAM (Random Access Memory) based on a command from the central processing circuit 202 and supplies the video signal to the liquid crystal display device 200 together with a timing signal. The central processing circuit 202 performs various operations based on the input from the external I / F circuit 203 and outputs commands to the display information processing circuit 201 and the external I / F circuit 203 based on the results. The external I / F circuit 203 sends information from the input / output device 204 to the central processing circuit 202 and controls the input / output device 204 based on a command from the central processing circuit 202. The input / output device 204 is a switch, a keyboard, a hard disk, a flash memory unit, or the like. The power supply circuit 205 supplies a predetermined power supply voltage to each of the above components.

  According to the above-described electronic apparatus, since the above-described liquid crystal display device 200 is provided, the same operations and effects as the above-described liquid crystal display device can be achieved, and the visibility can be maintained well under any circumstances. Power consumption can be reduced, and for example, the battery driving time can be extended.

The electronic device may be a monitor, a TV, a notebook computer, a PDA, a digital camera, a video camera, a photo viewer, a video player, a DVD player, an audio player, etc. in addition to the mobile phone as shown in FIG. Good.
In the above-described embodiment, the backlight control unit 12 that controls the backlight unit 8 shown in FIGS. 5, 10, and 13 is provided in the liquid crystal display device 200. This can also be realized by performing calculations in the central processing circuit 202 and controlling the power supply circuit 205.

It is a partially broken perspective view showing the liquid crystal panel for demonstrating embodiment of the liquid crystal display device which concerns on this invention. It is a schematic diagram showing the 1st board | substrate for describing embodiment of the liquid crystal display device which concerns on this invention. It is the elements on larger scale showing the 1st board for explaining an embodiment of a liquid crystal display concerning the present invention. It is a graph showing the relationship between the illumination intensity of the backlight for demonstrating embodiment of the liquid crystal display device which concerns on this invention, and the illumination intensity of external light. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining a first embodiment of a liquid crystal display device according to the present invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 1st specific example about 1st Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 2nd specific example about 1st Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 3rd specific example about 1st Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 4th specific example about 1st Embodiment of the liquid crystal display device which concerns on this invention. It is a schematic diagram for demonstrating 2nd Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 1st specific example about 2nd Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the 2nd specific example about 2nd Embodiment of the liquid crystal display device which concerns on this invention. It is a schematic diagram for demonstrating 3rd Embodiment of the liquid crystal display device which concerns on this invention. It is sectional drawing showing the liquid crystal panel for demonstrating the specific example about 3rd Embodiment of the liquid crystal display device which concerns on this invention. It is a schematic diagram for demonstrating other embodiment of the liquid crystal display device which concerns on this invention. It is a perspective view showing the electronic device for describing embodiment of the electronic device which concerns on this invention. It is a block diagram showing the structure of the electronic device for describing embodiment of the electronic device which concerns on this invention.

Explanation of symbols

1 Liquid crystal module 2 Active matrix substrate (first substrate)
3 Counter substrate (second substrate)
4 Liquid crystal materials (liquid crystal)
5 Sealing material 8 Backlight unit (lighting device)
12 Backlight control unit (lighting control means)
21, 121 First photosensor 22, 122 Second photosensor 23 Pixel switching element (active element)
28 128 Outside light shielding film (outside light shielding part)
31 Gate electrode 31 ′ Bottom gate electrode 32 Source electrode 33 Drain electrode 35 Reflective electrode 37 Black matrix (black matrix layer)
38 Color material (color filter layer)
58 Base material 60,160 Backlight shielding film (illumination light shielding part)
61 1st backlight light shielding film (illumination light light shielding part)
62 2nd backlight light shielding film (illumination light shielding part)
63 Transistor light shielding layer (light shielding film)
70 Electronic Device 200 Liquid Crystal Display Device

Claims (15)

A liquid crystal panel in which liquid crystal is sealed between first and second substrates, an illuminating device for irradiating light on the surface of the first substrate of the liquid crystal panel, and a light detection means for detecting the illuminance of ambient light And an illumination control means for controlling the illumination device according to a detection result by the light detection means,
The light detection means includes first and second photosensors respectively provided on the first substrate or the second substrate, and the first photosensor is irradiated with at least external light, The second photosensor is a liquid crystal display device characterized in that at least external light irradiation is blocked by an external light shielding unit.   The liquid crystal display device according to claim 1, wherein the second photosensor is irradiated with light from the illumination device.   The illuminance of the illumination device is changed to different first and second illuminances, and the output value of the second photosensor at the first illuminance and the output value of the second photosensor at the second illuminance. The liquid crystal display device according to claim 2, further comprising means for calculating the illuminance of outside light from the difference between the liquid crystal display device and the liquid crystal display device.   2. The liquid crystal display device according to claim 1, wherein at least one of the first photosensor and the second photosensor is blocked from irradiating light from the illumination device by an illumination light shielding unit. . In the first photosensor, irradiation of light from the illumination device is blocked by an illumination light shielding unit,
The second photosensor is irradiated with light from the illumination device,
Means for setting the illuminance of the lighting device to a specific value and detecting the magnitude of the external light illuminance with respect to the specific value from the difference between the output value of the first photosensor and the output value of the second photosensor is provided. The liquid crystal display device according to claim 1. The first substrate or the second substrate is an active matrix substrate in which active elements are arranged on the liquid crystal side surface,
The active element is a bottom-gate transistor or a four-terminal transistor having a bottom gate electrode between the active layer and the base material of the first substrate,
The liquid crystal display device according to claim 4, wherein the illumination light shielding portion is a film formed of the same material as the bottom gate electrode. The first substrate or the second substrate is an active matrix substrate in which active elements are arranged on the liquid crystal side surface,
The active element is a top-gate transistor having a transistor light-shielding layer between the active layer and the base material of the first substrate,
The liquid crystal display device according to claim 4, wherein the illumination light shielding portion is a film formed of the same material as the transistor light shielding layer. The first substrate is an active matrix substrate in which active elements are disposed on the liquid crystal side surface,
The active element is a transistor having a gate electrode;
The liquid crystal display device according to claim 1, wherein the external light shielding portion is a film made of the same material as the gate electrode. The first substrate is an active matrix substrate in which active elements are disposed on the liquid crystal side surface,
9. The liquid crystal display device according to claim 1, wherein the external light shielding portion is a film formed of the same material as the data lines of the active matrix substrate. A reflective electrode is provided on the liquid crystal side surface of the first substrate,
The liquid crystal display device according to claim 1, wherein the external light shielding portion is a film formed of the same material as the reflective electrode. A black matrix layer is provided in a display area for displaying an image on at least one of the liquid crystal side surfaces of the first substrate and the second substrate,
The liquid crystal display device according to claim 1, wherein the external light shielding portion is a film formed of the same material as the black matrix layer. A color filter layer is provided in a display area for displaying an image on at least one of the liquid crystal side surfaces of the first substrate or the second substrate,
The liquid crystal display device according to claim 1, wherein the external light shielding portion is a film formed of the same material as the color filter layer. The color filter layer includes a first color filter layer corresponding to blue display, a second color filter layer corresponding to green display, and a third color filter layer corresponding to red display. ,
The external light shielding portion is made of a film made of the same material as the first color filter layer, a film made of the same material as the second color filter layer, or made of the same material as the third color filter layer. The liquid crystal display device according to claim 12, wherein two or more kinds of films are formed to overlap each other.   The liquid crystal display device according to claim 1, wherein the external light shielding portion is formed of the same resin as a sealing material interposed between the first and second substrates. .   An electronic apparatus comprising the liquid crystal display device according to claim 1.

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