JP2005043833A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device with a simple structure in which an excellent illumination effect is brought about by making background colors partially vary. <P>SOLUTION: The liquid crystal display device is provided with a backlight 12 on the rear side of a liquid crystal panel 11. The backlight 12 is provided with a light transmitting back plate 13 opposite to the rear face of the liquid crystal panel 11. The back plate 13 consists of a light guide plate 13A and a light diffusing plate 13B and a first light source 14 is disposed in the vicinity of an end face of the light guide plate 13A. Further, a reflection plate 16 is disposed on the rear side of the light guide plate 13A and a second light source 18 emitting light with a color different from that of the first light source 14 is disposed on the outside of the reflection plate 16. One end face of a light guide 19 faces the second light source 18 and the other end faces of the light guide 19 are placed opposedly to the rear face part of the liquid crystal panel 11 via the back plate 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device used as a display of electrical equipment, and more particularly to a liquid crystal display device that exhibits an illumination effect when used.

  2. Description of the Related Art Conventionally, a liquid crystal display device (LCD: Liquid Crystal Display) that consumes less power and is thin and light has been widely used as a display device used in an audio device or the like. The LCD has an electrical addressing method, a thermal addressing method, and an optical addressing method. Of these, the electrical addressing method is roughly divided into a segment electrode driving method and a matrix electrode driving method depending on the difference in electrode configuration. Further, the former is classified into static driving and dynamic driving, and the latter is classified into passive matrix (PM) driving and active matrix (AM) driving according to the difference in the electric addressing method.

  Above all, TFT-driven AM-LCDs using thin transistors such as a-Si and p-Si types are excellent in display performance such as contrast and response. However, in any LCD, the liquid crystal panel itself does not emit light, so external illumination light Need. Among them, there is a reflective liquid crystal panel that uses natural light as external irradiation light, but the transmissive type is the mainstream that requires brightness and image quality, and a backlight is provided on the back side.

  Such LCD backlights are roughly divided into three types: a reflector method (directly-under method), a light guide method (edge light method), and a planar light source method. A fluorescent lamp or the like is housed in an optical housing composed of the above, and the surface light source is formed by reflecting and diffusing the emitted light. In the light guide system, the light emitted from a light emitter such as a fluorescent lamp is incident from the side of a light guide plate such as acrylic or polycarbonate, and the incident light is reflected multiple times within the light guide plate to form a surface light source. The planar light source system uses a planar light source such as a cold cathode flat fluorescent lamp or EL (electroluminescence) as it is.

  FIG. 5 shows a cross section of an LCD module having a reflector type backlight. P is a liquid crystal panel, and L1 is a backlight. The backlight L1 is configured by providing a light emitter E1 inside a housing C1 whose inner surface forms a reflecting surface and a light diffusing plate D1 at the front opening of the housing C1. Is done.

  FIG. 6 shows an example of an LCD module provided with a light guide type backlight. The backlight L2 is configured by housing a light guide plate T made of acrylic or the like in a housing C2 whose inner surface forms a reflective surface. The In addition, a light emitter E2 facing both end faces of the light guide plate T is accommodated in the housing C2, and a liquid crystal panel P is disposed on the front surface of the light guide plate T via a light diffusion plate D2.

  Here, in recent years, a color LCD that can display characters and figures on a screen in color using a color filter is also widely used. However, a color LCD is disadvantageous in that it is more expensive than a monochrome type. Some monochrome type liquid crystal panels can switch the background color of the backlight to red or green. However, this type of backlight does not display two or more colors as the background color at the same time. It's just a literal lighting function that irradiates the entire panel with light.

  Therefore, there has been proposed a liquid crystal display device that uses two types of light sources having different emission colors as an LCD backlight, can partially change the background color, and can emphasize characters and figures displayed in the area (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 11-231804.

  However, in the liquid crystal display device disclosed in Patent Document 1, the first light source is allowed to face the end surface of the light guide plate facing the back surface of the liquid crystal panel, and the second light source is provided facing the back surface of the light guide plate. Therefore, the first light source and the second light source cannot be mounted on the same circuit board.

  In addition, a color filter is interposed between the liquid crystal panel and the light guide plate so that the emitted light of the second light source directly irradiated on the back surface of the light guide plate is transmitted through the light guide plate and irradiated from the part of the color filter to the back surface of the liquid crystal panel. Therefore, even though the light transmission region (second pattern) of the second light source formed in the color filter can be set to a different background color from other regions, a large number of regions having different background colors are scattered. In such a case, a large number of light transmission regions of the second light source must be formed in the color filter, and a considerable number of second light sources are required to make each region emit light with the same luminance, and the size of the apparatus is large. There is a disadvantage that it leads to increase in cost and cost.

  The present invention has been made in view of the circumstances as described above, and its purpose is to provide a superior illumination by illuminating a large number of areas with a background color different from other areas with a small number of light sources without using a color filter. An object of the present invention is to provide a liquid crystal display device having a simple structure that exhibits an effect.

  In order to achieve the above object, the present invention provides a liquid crystal display device having a backlight on the back side of a liquid crystal panel. The backlight includes a light-transmitting back plate facing the back surface of the liquid crystal panel, and one end surface of the back plate. A first light source that generates light to be irradiated on the back surface of the liquid crystal panel, and the first light source emits light of a different color, and the first light source passes through the light shielding member so that the emitted light does not directly shine on the back plate. A second light source disposed on the same plane as the light source, and a plurality of linear light guides having one end surface facing the second light source and the other end surface opposed to the back surface of the liquid crystal panel. The radiated light of the second light source is irradiated on the back surface of the liquid crystal panel.

  According to the liquid crystal display device of the present invention configured as described above, an excellent illumination effect can be obtained by partially changing the background color of the display surface without using a color filter. In particular, the first light source and the second light source are emitted from the second light source while irradiating the back surface of the liquid crystal panel through the light guide while irradiating the entire back surface of the liquid crystal panel with the radiated light of the first light source. The light source can be provided on the same plane and the same substrate to reduce the size and cost of the apparatus, and by using a plurality of light guides, a large number of portions of the display surface can be made bright with one second light source. Can shine.

  Hereinafter, the present invention will be described. The liquid crystal display device according to the present invention is a transmissive type including a backlight on the back side of the liquid crystal panel, and the backlight is a light transmissive back plate facing the back surface of the liquid crystal panel, and the back plate. A first light source that generates light emitted from one end face of the liquid crystal panel to the back surface of the liquid crystal panel, and the first light source emits light of a different color, and a light shielding member is provided so that the emitted light does not directly shine on the back plate. A second light source disposed on the same plane as the first light source, and a plurality of linear light guides having one end surface facing the second light source and the other end surface opposed to the back surface of the liquid crystal panel. Configured. According to the liquid crystal display device, the first light source and the second light source are provided on the same plane and on the same circuit board to emit light, and the back light of the first light source is irradiated on the entire back surface of the liquid crystal panel through the light guide. The back surface of the liquid crystal panel is irradiated with the radiated light of the second light source, and the liquid crystal panel can be partially illuminated with light different in color from the first light source. The backlight may be either a light guide system or a reflector system.

  In FIG. 1, reference numeral 11 denotes a normally white liquid crystal panel, and reference numeral 12 denotes a backlight provided on the back side. The backlight 12 includes a light-transmitting back plate 13 facing the back surface of the liquid crystal panel 11, and a back plate. The first light source 14 arranged on the side of the 13 is an edge light system. In this example, the back plate 13 is composed of a light guide plate 13A made of a transparent material such as acrylic or polycarbonate, and a translucent light diffusing plate 13B provided on the front surface of the light guide plate 13A. A reflector 16 is provided via a projection template 15 made of In particular, the reflecting plate 16 forms a casing for connecting the liquid crystal panel 11 and the back plate 13, and a circuit board 17 for lighting the first light source 14 is fixed to one end side of the casing, and is mounted on the circuit board 17. The first light source 14 faces the one end surface of the light guide plate 13A. The first light source 14 may be a red LED, a blue LED, a yellow LED, an orange LED, or a green LED, an RB-type two-color LED, or an RGB-type multi-color LED. May be used.

  A second light source 18 that emits light of a different color from the first light source 14 is mounted on the circuit board 17. Various lamps as described above are used for the second light source 18. When a two-color LED or a multi-color LED is used for the second light source 18, the second light source 18 is controlled to generate light of a different color from the first light source 14. In particular, the second light source 18 is disposed outside the reflection plate 16 that forms a casing (a light shielding member that does not directly radiate light emitted from the second light source 18 to the back plate 13). Do not shoot directly.

  Reference numeral 19 denotes a plurality of linear light guides for guiding the radiated light of the second light source to the inside of the reflector, and each one end face thereof faces the second light source 18 as the light receiving portion 19A, and the other end face of these light guides is projected. It faces the back surface of the liquid crystal panel 11 through the back plate 13 as the light portion 19B. The light guide 19 has a core made of a transparent material having high transparency (in this example, a transparent resin), and a cladding layer having a refractive index smaller than that of the core is formed on the outer peripheral surface thereof. About 3 mm. One end side thereof is held by a bracket (not shown) protruding from the reflection plate 16, and the other end side is inserted into a through hole formed in the reflection plate 16 and fixed. An optical cable in which a plurality of optical fibers are bundled is used as the light guide 19, and one end surface thereof faces the second light source 18, and the other end side is branched so that each branch end is connected to the back surface of the liquid crystal panel 11. You may make it oppose.

  Next, FIG. 2 is a perspective exploded view in which the liquid crystal display device is partially omitted. As is apparent from this figure, the projection template 15 is provided with a projection pattern 15A that is shaped like a star corresponding to one end light projecting portion 19B of the light guide 19.

  According to the liquid crystal display device as described above, when the first light source 14 is turned on, the radiated light enters from the end face of the light guide plate 13A, and the incident light is multiple-reflected inside the light guide plate 13A and the back plate. The entire 11 back surface of the liquid crystal panel 1 is irradiated from the light diffusing plate 13B forming the front surface. Therefore, the entire surface (display surface) of the liquid crystal panel 11 is uniformly illuminated by the emission color of the first light source 14.

  On the other hand, when the second light source 18 is turned on, the emitted light enters from one end face of the light guide 19, and the incident light radiates from the other end face into the projection pattern 15 A of the projection template through the inside of the light guide 19. Light passes through the back plate 13 and irradiates the back surface of the liquid crystal panel 11 at a right angle. Therefore, the projection pattern 15A partially appears on the display surface as shown in FIG. 3, and this shines in the same color as the second light source that emits light different in color from the first light source. In particular, the second light source 18 is preferably blinked, so that the display surface can be partly shined like a star to increase the illumination effect, and the second light source 18 employs a multi-color LED to emit light. By sequentially switching the colors, the illumination effect is further improved. In this example, the projection template 15 may be omitted.

  In FIG. 4, reference numeral 21 denotes a normally white type liquid crystal panel as in the first embodiment, and reference numeral 22 denotes a backlight provided on the back side thereof. The backlight 22 is an optical housing 25 composed of a back plate 23 and a reflecting plate 24. The reflector is provided with a first light source 26 inside. In this example, the back plate 23 is formed of a light diffusing plate provided at the front opening of the reflecting plate 24 so as to face the back surface of the liquid crystal panel 21, and the reflecting plate 24 is a semi-cylindrical body made of white resin. A circuit board 27 for lighting the first light source 26 is fixed to the outer surface of the reflecting plate 24, and the first light source 26 mounted on the circuit board 27 is inserted into the inside from the side surface of the optical housing 25. As a configuration. The first light source 26 may be a red LED, a blue LED, a yellow LED, an orange LED, or a green LED, as well as an RB type two-color LED or an RGB type multi-color LED. A cold cathode tube or the like may be used.

  On the other hand, a second light source 29 mounted on the circuit board 28 is provided outside the optical housing 25 so that the radiated light is shielded by the reflecting plate 24 (light shielding member) so that the back plate 23 is not directly irradiated. The second light source 29 uses various lamps that emit light of a different color from the first light source. When a two-color LED or a multi-color LED is used for the second light source 29, light of a different color from the first light source 26 is generated. To be controlled.

  Reference numeral 30 denotes a light guide similar to the above example. Each end face thereof faces the second light source 29 as the light receiving portion 30A, and the other end face of these light guides serves as the light projecting portion 30B from the inside of the optical housing 25 to the back plate 23. The liquid crystal panel 21 is opposed to the back surface portion. One end side of the light guide 30 is fixed to the penetrating portion of the reflecting plate 24, and the other end surface forming the light projecting portion 30B is fixed to the back plate 23 with an adhesive or the like.

  Here, according to the liquid crystal display device as described above, when the first light source 26 is turned on, the radiated light is reflected and diffused in the optical housing 25, and the entire back surface of the liquid crystal panel 21 from the back side one end surface of the back plate 23. Irradiate. Therefore, the entire surface (display surface) of the liquid crystal panel 21 is uniformly illuminated by the emission color of the first light source 26.

  On the other hand, when the second light source 29 is turned on, the emitted light enters from one end face of the light guide 30, the incident light radiates from the other end face through the inside of the light guide 30, and the emitted light passes through the back plate 23. The back surface of the liquid crystal panel 21 is irradiated at a right angle. Therefore, as in the first embodiment, the display surface partially shines in the same color as the second light source 29, and an illumination effect is exhibited.

  The projection template 15 used in the first embodiment may be overlapped on the back surface of the back plate 23, or the projection pattern 15A may be formed on the back plate 23 so that the light guide light projecting portion 30B is opposed thereto. . 4 shows a state in which the first light source 26 and the second light source 29 are mounted on separate circuit boards 27 and 28, the light sources 26 and 29 can be provided on the same plane.

Schematic cross-sectional view of a liquid crystal display device according to the present invention An exploded perspective view with the device partially omitted Explanatory drawing showing the display surface Schematic cross section showing another embodiment of the liquid crystal display device according to the present invention. Schematic cross-section of a conventional device equipped with a light guide type backlight Schematic cross-section of a conventional device with a reflector-type backlight

Explanation of symbols

11, 21 Liquid crystal panel 12, 22 Backlight 13, 23 Back plate 13A Light guide plate 13B Light diffusing plate 14, 26 First light source 15 Projection template 16, 24 Reflector 18, 29 Second light source 19, 30 Light guide 17, 27, 28 Circuit board

Claims (1)

In a liquid crystal display device having a backlight on the back side of the liquid crystal panel, the backlight transmits a light-transmitting back plate facing the back surface of the liquid crystal panel, and light irradiated on the back surface of the liquid crystal panel from one end surface of the back plate. The generated first light source and the first light source emit light of different colors and are arranged on the same plane as the first light source via a light shielding member so that the emitted light does not directly shine on the back plate. Two light sources and a plurality of linear light guides having one end faced to the second light source and the other end faced to the back surface of the liquid crystal panel, and the emitted light of the second light source is liquid crystal through the light guides. A liquid crystal display device characterized in that the back surface of the panel is irradiated.

Images