JP2007193242A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of switching a transmission type color display to a reflection type mono-tone display and vice versa in accordance with strength of external light with a simple constitution. <P>SOLUTION: The liquid crystal display comprises: a liquid crystal panel 20 made by arranging a color display region X provided with a color filter 27 coloring the light transmitted thereby and a mono-tone display region Y which transmits the transmitted light as it is, in a prescribed pattern in the panel; a back light 40 which is disposed behind the liquid crystal panel 20 and is provided with a reflection mirror 44 of reflecting light transmitted from the mono-tone display region Y of the liquid crystal panel 20 to the mono-tone display region Y on a position opposite to the mono-tone display region Y; and a light controller 60 which controls an amount of light outputted by the back light 40. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device capable of switching between a transmissive color display and a reflective monotone display in accordance with an external light environment.

  The structure of the liquid crystal display device includes a transmission type and a reflection type. The transmissive liquid crystal display device has a structure that displays the image by transmitting the light emitted from the backlight from the back of the display screen. It is easy to see in dark places where the outside light is dark, such as at night or indoors. It is difficult to see in bright light. On the other hand, a reflection type liquid crystal display device has a structure that displays a picture using a light reflected from outside light such as sunlight as a light source on the back of the display screen. It is difficult to see.

  Conventionally, there has been proposed a liquid crystal display device that has the advantages of both the transmission type and the reflection type in its function, and displays the reflection type in a bright place and displays the transmission type in a dark place (for example, Patent Documents). 1-2).

Patent Document 1 discloses a liquid crystal display device having a structure in which a magic mirror is provided between a liquid crystal panel and a backlight.
Patent Document 2 discloses a liquid crystal display device having a structure in which a reflector is provided on the back surface of a backlight provided on the back surface of a liquid crystal panel.
No. 2001-264748 2005-181728

  By the way, when comparing the image quality of the liquid crystal between the monotone display and the color display, the reflection type employed outdoors with strong external light such as sunlight is easier to see in detail because the contrast of light and dark is larger in the monotone. On the other hand, color is overwhelmingly more expressive for transmissive liquid crystals that are used indoors where external light is weak.

  However, the liquid crystal display devices disclosed in each of the above-mentioned patent documents are rich in color in such a reflective monotone display that can be displayed clearly and with high definition in an environment with strong external light, and in an environment with low external light. It does not have a configuration and function that can be switched to the transmissive color display liquid crystal.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display device capable of switching display between a reflective monotone and a transmissive color in accordance with an outside light environment with a simple configuration. To do.

In order to achieve the above object, the present invention is a liquid crystal display device,
A liquid crystal panel in which a color display unit having a color filter for coloring transmitted light and a monotone display unit for transmitting the transmitted light as they are arranged in a predetermined pattern on the panel surface;
A backlight provided behind the liquid crystal panel and provided with a reflective portion that reflects external light transmitted through the monotone display portion of the liquid crystal panel toward the monotone display portion, at a position facing the monotone display portion;
It comprises light control means for adjusting the amount of light output from the backlight (first invention).
The liquid crystal display device according to the present invention has a structure in which light emitted from the backlight is transmitted through the color display unit including the color filter of the liquid crystal panel and transmitted to the front surface in an environment where the outside light is weak such as indoors. In addition, transmissive color display with rich image colors can be achieved, and in an environment with strong external light such as outdoors, the external light incident on the monotone display section of the liquid crystal panel from the front of the liquid crystal screen is reflected in the backlight. Since the portion has a reflecting structure, a reflection type monotone display with a remarkable contrast between light and shade can be achieved.

According to a second invention, in the first invention, an illuminance sensor that detects the illuminance on the liquid crystal display surface of the liquid crystal display device, and an amount of light emitted from the backlight by the dimming means according to the illuminance detected by the illuminance sensor And a control means capable of controlling the adjustment.
The liquid crystal display device according to the present invention can switch between transmissive color display and reflective monotone display according to the intensity of external light applied to the liquid crystal display surface.

A third invention is characterized in that in the second invention, there is provided a light shielding means capable of shielding light incident on the illuminance sensor.
According to the liquid crystal display device of the present invention, it is possible to switch between transmissive color display and reflective monotone display as needed by operating the light shielding means.

  According to the present invention, it is possible to provide a liquid crystal display device capable of switching between transmissive color display and reflective monotone display in accordance with the intensity of external light with a simple configuration.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a liquid crystal display device 10 according to the present embodiment. As shown in FIG. 1, the liquid crystal display device 10 includes a liquid crystal panel 20, a backlight 40, a dimmer 60, an illuminance sensor 80, a control unit 90, and a light shielding plate 100.

  FIG. 2 is an enlarged cross-sectional view showing in detail the laminated structure of the liquid crystal panel 20 and the backlight 40. The liquid crystal panel 20 is, for example, an active matrix drive type liquid crystal panel. As shown in FIG. 2, the liquid crystal 22 and an alignment film 23, a transparent electrode 24, and a glass substrate laminated on the both sides of the liquid crystal 22 in order from the inside. 25 and the polarizing filter 26, and a color filter 27 disposed between the transparent electrode 24 on the front side and the glass substrate 25.

  For the liquid crystal 22, for example, a general-purpose nematic type liquid crystal is used. The alignment film 23 is a film for aligning the molecules of the liquid crystal 22 in a certain direction. The transparent electrode 24 is a highly transparent electrode provided as a pair so as to sandwich the liquid crystal 22 and the alignment film 23 from both sides. The amount of light transmitted through the liquid crystal panel 20 is controlled by changing the voltage applied between each pair of the transparent electrodes 24. That is, the electrode surface of each pair of transparent electrodes 24 corresponds to a pixel which is the smallest display unit on the screen.

  FIG. 3 is a diagram illustrating an example of a planar arrangement of the transparent electrodes 24 constituting the liquid crystal panel 20. As shown in FIG. 3, the transparent electrodes 24 are processed into, for example, a rectangular flat plate shape, and are arranged in a plane in the vertical and horizontal directions on the screen.

  The glass substrate 25 insulates the current flowing through the transparent electrode 24. The polarizing filter 26 has a property of transmitting only light in a specific direction, and the polarizing filter 26 on the front surface and the polarizing filter 26 on the back surface are arranged so that the light transmitting directions are orthogonal to each other.

  The color filter 27 is composed of a resin film containing a dye or a pigment, and R (red), G is provided at a position facing the transparent electrode 24 between the transparent electrode 24 and the glass substrate 25 on the front side of the liquid crystal panel 20. They are arranged in the three primary color patterns of (green) and B (blue). Thereby, the light transmitted from the backlight 40 through the liquid crystal panel 20 is colored, and various colors can be displayed by additive color mixing by adjusting the amount of light transmitted through each of the RGB color filters 27. The planar arrangement of the color filters 27 arranged on the liquid crystal panel 20 in the present embodiment includes, for example, a color display area X where the color filters 27 are arranged and a monotone display area where the color filters 27 are not arranged, as shown in FIG. Y.

  FIG. 4 shows an example of a planar arrangement of the color filters 27 constituting the liquid crystal panel 20. As shown in FIG. 4, the color filter 27 is arranged in a plane in the vertical and horizontal directions so that the color display area X where the color filter 27 is arranged and the monotone display area Y where the color filter 27 is not arranged are alternated. The

  Referring to FIG. 2 again, the backlight 40 according to this embodiment includes a light projecting unit 42 and a reflecting mirror 44. The light projecting unit 42 includes, for example, a direct type that is a method in which fluorescent lamps are arranged on the back surface of a liquid crystal panel, or a fluorescent lamp, a light guide plate, and a diffusion plate, and has a uniform surface by scattering and diffusing light. A light guide type that is a method of using a light source is used.

  FIG. 5 shows an example of a planar arrangement of the reflecting mirrors 44 constituting the backlight 40. As shown by a solid line in FIG. 5, the reflecting mirror 44 is provided at a position corresponding to the area Y on the front surface of the backlight unit 42, and external light transmitted through the monotone display area Y of the liquid crystal panel 20 is converted into the monotone display area. It is for reflection to Y.

  The dimmer 60 adjusts the amount of light emitted from the backlight 40 and switches on and off. For example, the voltage applied to the backlight 40 can be adjusted and controlled by an external adjustment knob or an external command signal. Module is used.

  The illuminance sensor 80 is a sensor that can measure the illuminance of light. For example, the edge of the frame (not shown) that does not interfere with the visual recognition of the image on the front of the screen, the inside of the backlight 40 (not shown), and the like. It is provided at a position where the light irradiated on the front surface of the screen can be detected.

  The control unit 90 discriminates the illuminance measured by the illuminance sensor 80, controls the dimmer 60, and adjusts the light emitted from the backlight 40.

  The light shielding plate 100 is a member capable of shielding light incident on the illuminance sensor 80. For example, the light shielding plate 100 can be disposed on the front surface of the illuminance sensor 80, and a slide opening / closing type metal plate that can manually switch between lighting and shading. Used as the light shielding plate 100.

  Hereinafter, a specific operation example of the control unit 90 will be described in detail with reference to FIGS. 6 and 7. FIG. 6 is a diagram illustrating a light path in a transmissive color display that is an image display in a state where the external light is weak. FIG. 7 is a diagram illustrating the liquid crystal display device 10 according to the present embodiment in a state where the external light is strong. It is a figure which shows the path | route of the light in the reflection type monotone display which is an image display.

  As shown in FIG. 6, when the illuminance measured by the illuminance sensor 80 is not more than a predetermined level in an environment where the outside light is weak such as at night or indoors, the control unit 90 responds to the transmissive color according to the illuminance. “Display” is determined, a command signal is sent to the dimmer 60, and the light emitted from the light projecting unit 42 of the backlight 40 is turned on. That is, the image displayed on the screen at this time has a path A through which the light emitted from the light projecting unit 42 of the backlight 40 passes through the color filter 27 arranged in the color display region X of the liquid crystal panel 20. Since it is displayed on the front, it is displayed in color.

  On the other hand, as shown in FIG. 7, when the illuminance measured by the illuminance sensor 80 is higher than a predetermined level in an environment with strong outside light such as outdoors in the daytime, the control unit 90 performs “reflection” according to the illuminance. Is determined to be “monotone display”, a command signal is sent to the dimmer 60, and the light emitted from the light projecting unit 42 of the backlight 40 is turned off. That is, the image displayed on the screen at this time is displayed on the front surface along the path B in which the light transmitted through the monotone display area Y of the liquid crystal panel 20 is reflected by the reflecting mirror 44 of the backlight 40. , Monotone display.

  As described above, according to the present embodiment, the light emitted from the light projecting unit 42 of the backlight 40 is arranged in the color display region X of the liquid crystal panel 20 in an environment where the outside light is weak such as indoors. Since it has a structure that transmits light through the filter 27 to the front surface, transmissive color display with a rich image color can be performed, and external light that passes through the monotone region Y of the liquid crystal panel 20 in an environment with strong external light such as outdoors. However, since the reflecting mirror 44 provided in the backlight 40 has a reflecting structure, a reflection type monotone display with a remarkable contrast between light and shade can be achieved.

  Further, according to the present embodiment, the illuminance sensor 80 that detects the illuminance irradiated on the front surface of the liquid crystal display device 10 and the illuminance measured by the illuminance sensor 80 are discriminated and the light emitted from the backlight 40 is adjusted. By including the control unit 90 that automatically controls the optical device 60, it is possible to automatically switch between transmissive color display and reflective monotone display according to the intensity of external light.

  Further, according to the present embodiment, the lighting sensor 80 can be selected for lighting and shading by opening and closing the shading plate 100 as necessary, and switching between transmissive color display and reflective monotone display can be performed. .

  In the present embodiment, the adjustment of the light emitted from the backlight 40 can be realized by automatic control of the dimmer 60 by the control unit 90 that discriminates the illuminance measured by the illuminance sensor 80. However, the amount of light emitted from the backlight 40 may be manually adjusted by adjusting an adjustment knob mounted on the dimmer 60.

  In the present embodiment, the light emitted from the backlight 40 is adjusted to either on or off by controlling the dimmer 60 by the control unit 90 that determines the illuminance measured by the illuminance sensor 80. However, the present invention is not limited to this, and the amount of light may be adjusted continuously or stepwise in accordance with the illuminance measured by the illuminance sensor 80 in the case of color display when external light is weak.

It is a figure which shows the structure of the liquid crystal display device which concerns on this embodiment. It is an expanded sectional view which shows the laminated structure of the liquid crystal panel and backlight which concern on this embodiment. It is the figure which showed an example of the planar arrangement of the transparent electrode which comprises the liquid crystal panel which concerns on this embodiment. It is the figure which showed an example of the planar arrangement of the color filter which comprises the liquid crystal panel which concerns on this embodiment. It is a figure which shows an example of the planar array of the reflective mirror which comprises the backlight which comprises the liquid crystal display device which concerns on this embodiment. It is a figure which shows the path | route of the light in the transmissive color display of the liquid crystal display device which concerns on this embodiment. It is a figure which shows the path | route of the light in the reflection type monotone display of the liquid crystal display device which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 20 Liquid crystal panel 27 Color filter 40 Backlight 42 Light projection part 44 Reflector 60 Dimmer 80 Light intensity sensor 90 Control unit 100 Light-shielding plate A Light path in color display B Light path in monotone display X Color display Area Y Monotone display area

Claims (3)

A liquid crystal display device,
A liquid crystal panel in which a color display unit having a color filter for coloring transmitted light and a monotone display unit for transmitting the transmitted light as they are arranged in a predetermined pattern on the panel surface;
A backlight provided behind the liquid crystal panel and provided with a reflective portion that reflects external light transmitted through the monotone display portion of the liquid crystal panel toward the monotone display portion, at a position facing the monotone display portion;
An apparatus comprising: a light control means for adjusting a light amount output from the backlight. The liquid crystal display device according to claim 1.
An illuminance sensor for detecting the illuminance on the liquid crystal display surface of the liquid crystal display device;
And a control unit capable of controlling the adjustment of the amount of light emitted from the backlight by the dimming unit according to the illuminance detected by the illuminance sensor. The liquid crystal display device according to claim 2,
An apparatus comprising a light shielding means capable of shielding light incident on the illuminance sensor.

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