JP2007163872A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the reduction in the feeling of contrast caused by irregular reflection of exit light in the outside direction of the direction wherea viewer views a screen even when ambient brightness becomes darker than when viewing usually. <P>SOLUTION: A optical sensor 14 is a detection means such as an illumination meter with a general-purpose photo-detecting element such as a photo-diode and a photo-transistor, and detects brightness (illuminance) of the light of the surroundings. A control part 10 judges whether or not the illuminance detected by the optical sensor 14 does not exceed a reference value, and when the illuminance is judged as the reference value or lower, the control part applies voltage to liquid crystal elements 22 for phase difference control, and changes a viewing angle characteristic of liquid crystal element 21 for display (liquid crystal display device) to a narrow viewing angle state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device capable of automatically controlling viewing angle characteristics according to ambient brightness.

  Various thin display devices such as LCD (Liquid Crystal Display), PDP, and organic / inorganic EL have been put into practical use. These display devices are effective not only for reducing the size and weight but also for reducing the power consumption as compared with the conventional CRT. Liquid crystal display devices are widely used in office automation equipment such as monitors, word processors, personal computers, etc., in addition to television and video.

In recent years, there has been a demand for higher added value of liquid crystal display devices. As an example, a liquid crystal display device for displaying images and a control liquid crystal device for controlling light incident on the display liquid crystal device are provided. There is disclosed a liquid crystal display device that can arbitrarily switch between a wide viewing angle characteristic and a narrow viewing angle characteristic depending on a use form (see, for example, Patent Document 1).
JP-A-11-174489

  By the way, when viewing content such as movies and watching before going to bed, it is assumed that the surroundings are darkened, but even if the surrounding brightness is darker than normal viewing Because the brightness of the display screen does not change from that during normal viewing, diffused light components reflected from the surrounding walls and floors of the light emitted from the display screen reach the viewer's eyes. There is a problem in that the viewer remembers a certain dazzling sensation by light other than the direct light component from the display screen obtained by looking directly at the display screen, and makes it difficult to sufficiently feel the contrast on the display screen. In addition, the reflected light around the viewer may make it easier for viewers to feel glare around the screen. If you keep watching for a long time in such a situation, it may be a factor that causes aging of human eyes.

  The present invention has been made in view of such circumstances, detects ambient brightness, controls light incident on a display liquid crystal element according to the detected brightness, and controls the liquid crystal. By adopting a configuration that controls the viewing angle characteristics of the display device, even if the surrounding brightness is darker than that during normal viewing, the screen is projected outward from the viewing direction. An object of the present invention is to provide a liquid crystal display device that can suppress a decrease in contrast caused by irregular reflection of incident light. For example, viewers can control the viewing angle to narrow when the surrounding brightness is low, such as when watching content such as movies or watching before going to bed, such as when watching with a dark surrounding. An object of the present invention is to provide a liquid crystal display device that can alleviate the feeling of glare around the screen.

  In the present invention, a backlight is disposed on the back surface of the control liquid crystal element, and an average luminance level per frame of the video signal is detected, and the luminance of the backlight is adjusted according to the average luminance level and the surrounding brightness. An object of the present invention is to provide a liquid crystal display device capable of suppressing the viewer's fatigue even when the viewer continues to watch for a long time in a dark environment. For example, when the ambient illuminance is low and the average luminance level is low, such as when watching a movie, increasing the backlight luminance increases the dynamic range of the intermediate gradation or low gradation. An object of the present invention is to provide a liquid crystal display device that can provide a viewer with a good viewing state.

  A liquid crystal display device according to the present invention is a liquid crystal display device including a display liquid crystal element for displaying an image and a control liquid crystal element for controlling light incident on the display liquid crystal element. The liquid crystal display device by detecting light incident on the display liquid crystal element according to the brightness detected by the detection means. It is characterized by controlling the viewing angle characteristics.

  In the present invention, the viewing angle characteristics of the liquid crystal display device are controlled by detecting the ambient brightness and controlling the light incident on the display liquid crystal element by the control liquid crystal element in accordance with the detected brightness. Control. Thereby, the viewing angle characteristic of the liquid crystal display device can be automatically changed according to the environment such as illumination in which the liquid crystal display device is installed.

  In the liquid crystal display device according to the present invention, the display liquid crystal element and the control liquid crystal element have a structure in which a liquid crystal substance is sealed between opposing substrates, and a voltage applied between the substrates causes a gap between the substrates. The twisted structure of the encapsulated liquid crystal material is controlled, and the field of view of the liquid crystal display device is supplied by supplying an applied voltage corresponding to the brightness detected by the detecting means to the control liquid crystal element. It is characterized by controlling angular characteristics.

  In the present invention, when the display liquid crystal element and the control liquid crystal element have a structure in which a liquid crystal substance is sealed between opposing substrates, the voltage applied between the substrates is changed to change the liquid crystal substance. Since the twisted structure can be controlled, the light applied to the display liquid crystal element is controlled by changing the voltage applied to the control liquid crystal element in accordance with the detected brightness, so that the field of view of the liquid crystal display device can be controlled. The angular characteristic can be changed.

  The liquid crystal display device according to the present invention is characterized in that when the brightness detected by the detection means is below a reference value, the liquid crystal display device is controlled to narrow the viewing angle.

  In the present invention, when the detected brightness is below the reference value, the viewing angle of the liquid crystal display device is narrowed. As a result, the viewing angle of the liquid crystal display device is narrowed when the surroundings are viewed darkly, such as when viewing content such as movies or viewing before going to bed, so reflection of light emitted from the display screen by the walls or floor It is possible to reduce the amount and suppress the decrease in contrast feeling as in the prior art. As a result, it is possible to reduce the viewer's feeling of glare around the screen by the reflected light.

  The liquid crystal display device according to the present invention further includes a storage unit for storing information relating to ambient brightness and information relating to information relating to a viewing angle to be set for the brightness, and the detection means Reading the information on the viewing angle corresponding to the information on the brightness detected in the step from the storage unit, and controlling the control liquid crystal element so as to provide a viewing angle characteristic according to the read information on the viewing angle Features.

  In the present invention, information (viewing angle information) in which information related to ambient brightness and information related to the viewing angle to be set for the brightness is associated is stored in the storage unit. And the information regarding the viewing angle corresponding to the information regarding the detected brightness is read from a memory | storage part. Then, the control liquid crystal element is controlled according to the read information regarding the viewing angle to obtain a viewing angle characteristic to be set. Thus, the viewing angle can be easily changed by storing the viewing angle information in the storage unit in advance. In addition, the viewer can easily set the viewing angle preferred by each viewer by appropriately changing the viewing angle information.

  The liquid crystal display device according to the present invention includes a backlight that emits light from the back surface of the control liquid crystal element, and a luminance level detection unit that detects an average luminance level per frame of the video signal. The brightness of the backlight is controlled according to the brightness detected in this way and the average brightness level detected by the brightness level detecting means.

  In the present invention, when a backlight is disposed on the back side of the control liquid crystal element and light is emitted from the back side of the control liquid crystal element, in addition to the detected brightness, the average per video signal frame The luminance level is detected, and the luminance of the backlight is controlled according to the average luminance level. Thereby, the brightness | luminance of a backlight can be automatically changed according to environments, such as illumination in which the liquid crystal display device is installed, and the kind of image | video currently viewed. Therefore, even when the viewer continues to watch for a long time in a dark environment, the viewer's fatigue can be suppressed.

  In the liquid crystal display device according to the present invention, the brightness detected by the detecting means is not more than a first reference value, and the average brightness level detected by the brightness level detecting means is not more than a second reference value. The backlight is controlled to increase its brightness.

  In the present invention, when the detected ambient brightness is not more than the first reference value and the average brightness level is not more than the second reference value, the brightness of the backlight is increased. As a result, when the ambient illuminance is low and the average luminance level is low, such as when watching a movie, the dynamic range of the intermediate gradation or low gradation is expanded by increasing the backlight luminance. It becomes possible to provide the viewer with a better viewing state.

  According to the present invention, the viewing angle characteristic of the liquid crystal display device is controlled by detecting ambient brightness and controlling the light incident on the display liquid crystal element by the control liquid crystal element in accordance with the detected brightness. Thus, the viewing angle of the liquid crystal display device can be automatically changed according to the environment such as illumination in which the liquid crystal display device is installed.

  According to the present invention, when the display liquid crystal element and the control liquid crystal element have a structure in which the liquid crystal material is sealed between the opposing substrates, the control liquid crystal element is disposed between the substrates according to the detected brightness. Since the twisted structure of the liquid crystal substance is controlled by changing the voltage applied to the liquid crystal, the viewing angle of the liquid crystal display device can be changed by controlling the light incident on the display liquid crystal element.

  According to the present invention, since the viewing angle of the liquid crystal display device is narrowed when the detected brightness is equal to or less than the reference value, the surroundings are darkened, such as watching content such as a movie or watching before going to bed. Since the viewing angle of the liquid crystal display device is narrowed when viewed, the amount of reflection of light emitted from the display screen due to the wall or floor can be reduced, and the conventional reduction in contrast can be suppressed. As a result, it is possible to reduce the viewer's feeling of glare around the screen by the reflected light.

  According to the present invention, the viewing angle information in which the information about the ambient brightness and the information about the viewing angle to be set for the brightness are associated is stored in the storage unit, and the detected brightness information is stored. Since the viewing angle to be set is determined by reading the information regarding the viewing angle corresponding to the viewing angle, the viewing angle can be easily changed by storing the viewing angle information in the storage unit in advance. . In addition, the viewer can easily set the viewing angle preferred by each viewer by appropriately changing the viewing angle information.

  According to the present invention, a backlight is disposed on the back surface of the control liquid crystal element, and an average luminance level per frame of the video signal is detected in addition to the detected brightness, and the backlight is determined according to the average luminance level. Since the brightness of the light is controlled, the brightness of the backlight can be automatically changed according to the environment such as illumination in which the liquid crystal display device is installed and the type of video being viewed. Therefore, even when the viewer continues to watch for a long time in a dark environment, the viewer's fatigue can be suppressed.

  According to the present invention, when the detected ambient brightness is equal to or lower than the first reference value and the average luminance level is equal to or lower than the second reference value, the backlight brightness is increased. When the surrounding illuminance is low and the average luminance level is low, the backlight luminance is automatically increased, and the dynamic range of the intermediate gradation or low gradation is expanded, so that the viewing state is better. It is possible to provide viewers with excellent effects.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

FIG. 1 is a block diagram showing a configuration of a liquid crystal display device according to the present invention.
The liquid crystal display device according to the present invention includes a control unit 10, a storage unit 11, an operation unit 12, an operation signal receiving unit 13, an optical sensor 14, a tuner unit 15, an external input unit 16, a selector unit 17, a decoder unit 18, a video signal. A processing unit 19, a display unit 20, and a speaker 30 are provided. The control unit 10 includes a microcontroller (microcomputer), and directly or indirectly controls the above-described units, and performs various functions according to a control program stored in a built-in ROM.

  The tuner unit 15 is connected to, for example, an antenna (not shown) arranged in the direction of the broadcast relay base, and selects and demodulates the video / audio signal in a specific frequency band from the video / audio signals transmitted from the broadcast relay base. . Currently, the terrestrial frequency bands that are widely used are the VHF band low frequency (90M to 108MHz), the VHF band high frequency (170M to 222MHz), and the UHF band (470M to 770MHz). The one-channel video / audio signal designated by the viewer is selected and output to the selector unit 17. Of course, a tuner corresponding to satellite broadcasting, cable TV broadcasting, or the like may be used. It is assumed that the latest program information (hereinafter referred to as EPG signal) is superimposed on the video / audio signal transmitted from the broadcast relay base.

  For example, a playback device such as a video or a DVD is connected to the external input unit 16, and the video / audio signal output from the playback device is output to the selector unit 17.

  The selector unit 17 is connected to the tuner unit 15 and the external input unit 16 described above, and has a function of selecting one of the video / audio signals input from the tuner unit 15 or the external input unit 16. The video / audio signal is output to the decoder unit 18.

  The decoder unit 18 includes a video decoder 18a, an EPG decoder 18b, and an audio decoder 18c. The decoder unit 18 separates the video / audio signal selected by the selector unit 17 into a video signal, an EPG signal, and an audio signal, and separates the separated video signal, EPG signal, and audio signal into the video decoder 18a, the EPG decoder 18b, and the audio. Each is supplied to the decoder 18c.

  The video decoder 18 a demodulates the video signal and outputs it to the video signal processing unit 19, and the audio decoder 18 c demodulates the audio signal and outputs it to the speaker 30. Further, an EPG signal indicating a program channel, program name, broadcast start time, broadcast end time, broadcast content, and the like is superimposed on the video / audio signal, and the EPG decoder 18b decodes the EPG signal to generate a video signal processing unit. 19 output. In addition, it is possible to grasp the program being broadcast and scheduled to be broadcast from the decoded EPG signal.

  The video signal processing unit 19 processes the video signal decoded by the video decoder 18a and the EPG signal decoded by the EPG decoder 18b to generate a signal related to the video to be displayed on the display unit 20, Output to the display unit 20 (display liquid crystal element 21). The video signal processing unit 19 also functions as an APL detection unit that detects an average luminance level (APL) per frame of the video signal.

  The display unit 20 has a configuration in which a display liquid crystal element 21, a phase difference control liquid crystal element 22, and a backlight 23 are arranged in this order when viewed from the display surface side. As shown in FIG. 2, the display liquid crystal element 21 (phase difference control liquid crystal element 22) has a liquid crystal substance (twisted structure) in which a chiral agent is added between opposing substrates 211, 212 (221, 222). This is a TN liquid crystal element in which a TN (twisted nematic) liquid crystal) 213 (223) is enclosed.

  When a voltage is not applied between the substrates, the TN liquid crystal element rotates and emits incident light according to the orientation of the liquid crystal molecules. However, when a voltage is applied between the substrates, The direction of the liquid crystal molecules changes along the direction of the electric field formed. By utilizing the characteristics of the liquid crystal molecules, the first polarizing plate 25 is disposed on the light incident side of the phase difference controlling liquid crystal element 22, and the second polarizing plate 26 is disposed on the light emitting side of the display liquid crystal element 21. To control the intensity.

  When no voltage is applied to the phase difference controlling liquid crystal element 22 (FIG. 2A), the phase difference controlling liquid crystal molecules 223 maintain the twisted alignment structure due to the influence of the chiral agent. As a result, the transmitted light component P of the first polarizing plate 25 changes in the polarization direction of Q1. Further, the light component in the polarization direction of R1 increases by being transmitted through the display liquid crystal element 21. Thus, since the polarization direction of the light emitted from the display liquid crystal element 21 matches the polarization direction S of the second polarizing plate 26, the contrast becomes high.

  On the other hand, when a voltage is applied to the liquid crystal element 22 for phase difference control (FIG. 2B), the twisted alignment structure of the liquid crystal molecules 223 for phase difference control is destroyed due to the influence of the applied voltage. As a result, the transmitted light component P of the first polarizing plate 25 changes to Q2 without changing its polarization direction much. Further, the light component in the polarization direction of R2 increases by being transmitted through the display liquid crystal element 21. Thus, since the polarization direction of the light emitted from the display liquid crystal element 21 does not coincide with the polarization direction S of the second polarizing plate 26, the contrast is lowered.

  As described above, the contrast characteristic in the front direction has been described. Since the contrast characteristic at a position deviated from the front has a positive relationship with the contrast characteristic in the front direction, the voltage difference is applied to the liquid crystal element 22 for controlling the phase difference. Contrast characteristics at a position deviated from the front face are lower than when no voltage is applied. That is, it becomes a narrow wide viewing angle state. Thus, in the liquid crystal display device of the present invention, the viewing angle is controlled by the voltage applied to the liquid crystal element 22 for phase difference control. The viewing angle is a numerical value that is a measure of how much the image displayed on the display unit 20 can be recognized at a position deviated from the front. Here, the viewing angle is an angle at which the contrast is 10: 1 or more.

  The operation unit 12 is provided in the liquid crystal display device body, and includes various operation buttons for operating basic operations of the liquid crystal display device, such as a main power button, an input switching button, a channel button, and a volume button. When each operation button is pressed, an operation signal is generated, and the control unit 10 controls each unit based on the generated operation signal.

  The operation signal receiving unit 13 is for receiving an operation signal transmitted from the remote operation unit (remote control) 3, and the operation of the liquid crystal display device is also operated by this operation signal. As described above, in the liquid crystal display device of this example, the liquid crystal display device is remotely operated using the remote controller 3 that is separate from the liquid crystal display device, or the liquid crystal display device is operated by the operation unit 12 provided on the main body of the liquid crystal display device. To do.

  As shown in FIG. 3, the remote controller 3 corresponding to the liquid crystal display device of the present invention includes a menu button 3a. When the viewer presses the menu button 3a, the conventional focus, H position, V position, etc. In addition to the initial setting, a menu screen that allows selection of the viewing angle setting for setting the viewing angle of the liquid crystal display device, which is characteristic of the present invention, is displayed on the display unit 20 by OSD.

  The optical sensor 14 is detection means such as an illuminometer equipped with a general-purpose photodetection element such as a photodiode or a phototransistor, and detects the brightness (illuminance) of ambient light. The optical sensor 14 is disposed, for example, on the upper surface or the rear surface of the cabinet of the liquid crystal display device so that the image light displayed on the display unit 20 does not enter the optical sensor 14. This is for the optical sensor 14 to detect ambient brightness, and to prevent the light from the display unit 20 from entering the optical sensor 14 and lowering the ambient brightness detection accuracy. It is.

In this example, it is possible to select between automatic contrast control that automatically sets the viewing angle according to ambient illuminance and automatic video control that automatically sets the viewing angle based on video.
In the case of automatic contrast control, the control unit 10 compares the illuminance detected by the optical sensor 14 with a reference value, and narrows the viewing angle of the liquid crystal display device when the illuminance is less than or equal to the reference value. On the other hand, in the case of automatic video corresponding control, the control unit 10 compares the APL detected by the video signal processing unit 19 functioning as the APL detection means with a reference value, and if the APL is less than the reference value, the liquid crystal display Try to narrow the viewing angle of the device. Since the viewing angle in the liquid crystal display device of this example is determined by the voltage applied to the liquid crystal element 22 for controlling the phase difference, the control unit 10 adjusts the liquid crystal for phase difference control so that the viewing angle of the liquid crystal display device is narrowed. A viewing angle control signal SIG1 that defines a voltage to be applied to the element 22 is generated, and the viewing angle is changed by applying the viewing angle control signal SIG1 to the phase difference control liquid crystal element 22.

  Unlike the PDP, FED, and the like, the liquid crystal element is not a self-luminous display element. Therefore, a backlight 23 having a plurality of discharge tubes as light sources is disposed on the back surface of the liquid crystal element 22 for phase difference control. As a backlight application, a cold cathode ray discharge tube (CCFL) that has a long life and emits white light close to natural light and generates little heat is used. A light source such as a light emitting diode may be used instead of the discharge tube.

  Then, the control unit 10 compares the illuminance detected by the optical sensor 14 with the reference value, and reduces the luminance of the backlight 23 when the illuminance is equal to or less than the reference value. Since the luminance of the discharge tube constituting the backlight 23 is determined by the pulse height and frequency of the applied high-frequency signal, the control unit 10 regulates the frequency of the high-frequency signal applied to the backlight 23 (discharge tube). The backlight luminance is changed by generating the light control signal SIG2 and applying the dimming control signal SIG2 to the backlight 23.

  FIG. 4 is a flowchart showing an example of a processing procedure performed by the liquid crystal display device according to the present invention. Such a processing procedure can be performed by incorporating a control program in the ROM built in the control unit 10 in advance.

  In the liquid crystal display device of this example, when the menu button 3a of the remote controller 3 is pressed, a menu screen as shown in FIG. 5 is displayed on the display unit 20 (step S1). In FIG. 5, in addition to the initial settings 60 such as the conventional focus, H position, and V position, a viewing angle setting 61 for setting the viewing angle of the liquid crystal display device, which is characteristic of the present invention, can be selected on the menu screen. It ’s like that.

  The control unit 10 determines whether or not the viewing angle setting 61 has been selected by the viewer on the menu screen (step S2). When the viewing angle setting 61 is not selected (S2: NO), the control unit 10 returns the process to S2. On the other hand, when the viewing angle setting 61 is selected (S2: YES), the control unit 10 displays a viewing angle setting screen as shown in FIG. 6 on the display unit 20 (step S3). In FIG. 6, on the viewing angle setting screen, automatic contrast control 71 that automatically sets the viewing angle according to ambient illuminance and automatic video control 72 that automatically sets the viewing angle based on video can be selected. It has been.

  Then, the control unit 10 determines whether or not the automatic contrast control 71 is selected by the viewer on the viewing angle setting screen (step S4). When it is determined in S4 that the automatic contrast control 71 is selected (S4: YES), the control unit 10 determines the viewing angle when the surrounding illuminance is equal to or lower than a reference value (hereinafter referred to as a low illuminance state). The voltage to be applied to the liquid crystal element for phase difference control 22 is determined so that becomes narrow (step S5). Note that S5 only determines the voltage applied to the phase difference controlling liquid crystal element 22 in the low illuminance state, and is not a step of changing the voltage applied to the phase difference controlling liquid crystal element 22.

  Next, the control unit 10 determines whether or not the illuminance detected by the optical sensor 14 is less than or equal to the reference value (step S6), and when it is determined that the illuminance is less than or equal to the reference value (S6: YES) The voltage determined in S5 is applied to the phase difference control liquid crystal element 22 to change the viewing angle characteristic of the display liquid crystal element 21 (liquid crystal display device) to the narrow viewing angle state (step S7). On the other hand, when it determines with illumination intensity exceeding a reference value (S6: NO), the control part 10 returns a process to S6. That is, when it is determined that the illuminance exceeds the reference value, the viewing angle characteristics of the display liquid crystal element 21 are not changed, and the wide viewing angle state is maintained.

  On the other hand, when it is determined in S4 that the automatic contrast control 71 has not been selected (S4: NO), the control unit 10 determines whether or not the automatic video control 72 has been selected by the viewer on the viewing angle setting screen. Determination is made (step S8). When it is determined in S8 that the automatic video correspondence control 72 has been selected (S8: YES), the control unit 10 has a narrow viewing angle when the APL is in a state equal to or less than a reference value (hereinafter referred to as a low APL state). Thus, the voltage to be applied to the phase difference control liquid crystal element 22 is determined (step S9). Note that, similarly to S5, S9 only determines the voltage applied to the phase difference control liquid crystal element 22 in the low APL state, and is not a step of changing the voltage applied to the phase difference control liquid crystal element 22.

  Then, the control unit 10 determines whether or not the APL detected by the video signal processing unit 19 is equal to or less than the reference value (step S10), and when it is determined that the APL is equal to or less than the reference value (S10: YES), the process proceeds to S7, the voltage determined in S9 is applied to the phase difference control liquid crystal element 22, and the viewing angle characteristic of the display liquid crystal element 21 is changed to the narrow viewing angle state. On the other hand, when it is determined that the APL exceeds the reference value (S10: NO), the control unit 10 returns the process to S10. That is, when it is determined that APL exceeds the reference value, the viewing angle characteristic of the display liquid crystal element 21 is not changed, and the wide viewing angle state is maintained. When it is determined in S8 that the automatic video control 72 has not been selected (S8: NO), the control unit 10 determines that there is no need to change the viewing angle, and ends the process.

  As described above, when the automatic contrast control 71 is selected, the viewing angle characteristic of the liquid crystal display device is changed to the narrow viewing angle state when the illuminance is below the reference value, and the automatic video control 72 is When selected, the viewing angle characteristic of the liquid crystal display device is changed to the narrow viewing angle state when APL is equal to or less than the reference value. Therefore, in a dark viewing environment, it is possible to suppress a decrease in contrast caused by, for example, irregular reflection of the emitted light from the display unit 20 toward the outside of the direction in which the viewer views the screen. .

FIG. 7 is a state diagram showing a state in which the viewing angle characteristics of the display screen are controlled in accordance with the surrounding illuminance.
In FIG. 7, the solid line shows the contrast curve in the normal state, the one-dot chain line shows the contrast curve in the low illuminance state, and the two-dot chain line shows the contrast curve in the high illuminance state.
By performing the viewing angle control process so that the viewing angle becomes narrower as the ambient illuminance decreases, the light emission component of the amount of light from the display screen in the wide viewing angle direction decreases, and therefore exists around the liquid crystal display device. Diffuse reflected light components reflected on walls and floors can be reduced. Therefore, it is possible to suppress the viewer from feeling a dazzling feeling in a low illuminance state.

  Furthermore, in addition to the viewing angle control process, when the ambient illuminance is low and the APL is low as in the case of watching a movie, by controlling the backlight brightness to be higher or lower, It becomes possible to view the intermediate gray level image level in a trial listening state that is optimal for the viewer. That is, in FIG. 4, the peripheral illuminance and APL are considered as separate elements, and the viewing angle is controlled according to the peripheral illuminance and APL. The backlight luminance may be controlled together. For example, as illustrated in FIG. 8, the control unit 10 determines whether or not the illuminance detected by the optical sensor 14 is equal to or less than a reference value (Step S <b> 21), and determines that the illuminance is equal to or less than the reference value. If so (S21: YES), the voltage to be applied to the phase difference control liquid crystal element 22 is determined so as to narrow the viewing angle (step S22). Further, the control unit 10 determines whether or not the APL detected by the video signal processing unit 19 is equal to or less than the reference value (step S23), and when it is determined that the APL is equal to or less than the reference value (S23: YES), the backlight brightness is set to be high (step S24). On the other hand, if it is determined that APL exceeds the reference value (S23: NO), the process is terminated without performing S24, that is, without changing the backlight luminance. As described above, when the ambient illuminance is low and the APL is low, by increasing the backlight luminance, the dynamic range of the intermediate gradation or the low gradation is expanded, and a better viewing state is provided to the viewer. Is possible.

  As shown in FIG. 9, viewing angle information in which ambient brightness (illuminance) A1, A2,... Is associated with viewing angles B1, B2,. 11a is stored in the storage unit 11 (see FIG. 1). For example, when the illuminance detected by the optical sensor 14 is A1 (lx), the control unit 10 accesses the storage unit 11 to view the viewing angle information. The viewing angle of the liquid crystal display device may be changed by reading the viewing angle B1 (°) corresponding to the illuminance A1 with reference to 11a. By storing the viewing angle information 11a in the storage unit 11 in advance, the viewing angle can be easily changed. In addition, the viewer can easily set the viewing angle desired by each viewer by appropriately changing the viewing angle information 11a.

It is a block diagram which shows the structure of the liquid crystal display device which concerns on this invention. It is a disassembled perspective view which shows the structure of the display part which consists of a liquid crystal element for a display, and a liquid crystal element for phase difference control. It is a schematic diagram of the remote control for liquid crystal display devices used for this invention. It is a flowchart which shows an example of the process sequence which the liquid crystal display device which concerns on this invention performs. It is a figure which shows an example of a menu screen. It is a figure which shows an example of a viewing angle setting screen. It is a state figure which shows a mode that the viewing angle characteristic of the display screen was controlled according to peripheral illumination intensity. It is a flowchart which shows another example of the process sequence which the liquid crystal display device which concerns on this invention performs. It is a figure which shows the outline | summary of viewing angle information.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control part 11 Memory | storage part 11a Viewing angle information 14 Optical sensor 19 Image signal processing part 20 Display part 21 Liquid crystal element for display 22 Liquid crystal element for phase difference control 23 Backlight 25 1st polarizing plate 26 2nd polarizing plate SIG1 Viewing angle control Signal SIG2 Dimming control signal

Claims (6)

In a liquid crystal display device comprising a display liquid crystal element for displaying an image and a control liquid crystal element for controlling light incident on the display liquid crystal element,
Having detection means for detecting ambient brightness;
The viewing angle characteristic of the liquid crystal display device is controlled by controlling the light incident on the display liquid crystal element by the control liquid crystal element according to the brightness detected by the detecting means. Liquid crystal display device. The display liquid crystal element and the control liquid crystal element are:
A structure in which a liquid crystal material is sealed between opposing substrates, and a twisted structure of the liquid crystal material sealed between the substrates is controlled by a voltage applied between the substrates;
2. The liquid crystal display according to claim 1, wherein a viewing angle characteristic of the liquid crystal display device is controlled by supplying an applied voltage corresponding to the brightness detected by the detection unit to the control liquid crystal element. apparatus. 3. The liquid crystal display device according to claim 1, wherein when the brightness detected by the detection unit is equal to or lower than a reference value, the liquid crystal display device is controlled to narrow a viewing angle. 4. A storage unit for storing information associated with information related to ambient brightness and information related to a viewing angle to be set for the brightness;
Read out information related to the viewing angle corresponding to the information related to brightness detected by the detecting means from the storage unit,
The liquid crystal display device according to any one of claims 1 to 3, wherein the control liquid crystal element is controlled so as to provide a viewing angle characteristic according to information on the read viewing angle. A backlight that emits light from the back surface of the control liquid crystal element;
A luminance level detecting means for detecting an average luminance level per frame of the video signal;
The brightness of the backlight is controlled according to the brightness detected by the detection means and the average brightness level detected by the brightness level detection means. A liquid crystal display device according to any one of the above. When the brightness detected by the detection means is less than or equal to the first reference value and the average brightness level detected by the brightness level detection means is less than or equal to the second reference value, the brightness of the backlight is increased. It controls as follows. The liquid crystal display device of Claim 5 characterized by the above-mentioned.

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