JP2006221050A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that since display is made dark at the time when external light is used more for that if color density of a color filter is made dense, it is needed to enhance reflection luminance and since constitution has to be changed for the purpose of controlling reflection luminance, costs are increased, in a semitransmission type color liquid crystal display. <P>SOLUTION: Luminance at the time when external light is used can be made more luminous without changing constitution of the other part of a semitransmission type liquid crystal panel by incorporating fine particles reflecting light into color resist of the color filter. When the similar method is applied to a transmission type liquid crystal panel, visual confirmation under an external light is made possible even if a semitransmission reflection film is not provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device used in an electronic device such as a mobile phone. Specifically, the present invention relates to an improvement in the brightness of a reflective display that uses outside light, which is light in a use environment.

Conventional liquid crystal display devices include a reflective display that uses external light such as natural light and room light, and a transmissive display that uses illumination light from a backlight so that the display can be observed in a bright place or a dark place. Some perform both display modes. As a configuration of such a liquid crystal display device, a configuration in which a transflective film is provided on the inner surface of a liquid crystal panel and a backlight is provided on the back surface is generally known and is referred to as a transflective display device. Yes. Further, it is known that a color filter is formed on the liquid crystal layer side of the transflective film so that color display is possible both when using the backlight and when using external light. Among them, a configuration in which a dielectric multilayer film is used as a transflective film and is formed inside a liquid crystal panel is known (see, for example, Patent Document 1). In addition, an example is also known in which a metal reflective film having a transmissive opening in a pixel is used as a transflective plate (see, for example, Patent Document 2).
JP 2000-284276 A (2nd page, Fig. 1-3) JP 2001-33778 A (page 2-3, FIGS. 1 and 2)

  In the configuration in which the color filter is formed on the liquid crystal layer side from the transflective film described in Patent Document 1, light passes through the color filter once when using the backlight, but twice when using external light. The light loss is greater when using external light than when using a light source. Therefore, when the color of the color filter is darkened, the reflective display when using external light is darkened accordingly. When an attempt is made to increase the reflected light intensity to obtain a bright reflective display with good visibility, when a dielectric multilayer film as in Patent Document 1 is used, the performance of the dielectric multilayer film is controlled to reflect the reflectivity. However, it is necessary to greatly sacrifice the transmitted light intensity. In addition, as in Patent Document 2, when a metal reflective film having a transmission opening in a pixel is used, a method of increasing the reflectance by controlling the aperture ratio is generally used. Will be sacrificed. Then, it is necessary to change the performance of the metal reflecting film, for example, the opening area, when the transmitted light intensity is important and when the reflected light intensity is important, and as a result, a new photomask or the like is required. Therefore, the process is complicated and costs are increased.

  In the present invention, fine particles that reflect light are contained in the color resist of the color filter so that the main light of the external light reaches the semi-transmissive reflection film and is reflected and visually recognized. Part of the light passes through a part of the color filter and is then reflected and emitted by the fine particles that reflect the light. Since the light reflected by the fine particles is reflected through one-half of the film thickness of the color filter on average, the reflected light intensity is larger than the reflected light reflected by the semi-transmissive reflective film. Therefore, the reflected light intensity to be visually recognized becomes larger than that in the case where there is no fine particle that reflects light, and bright reflection display is possible. In addition, when the transflective film is a metal reflective film in which a transmissive opening is provided in the pixel, even the opening is bright due to the effect that there is a constant amount of reflected light from fine particles that reflect light. Reflective display is possible.

  By incorporating fine particles that reflect light in the color resist of the color filter, the brightness when using external light can be increased without changing the configuration of other parts of the transflective LCD panel. There is. In addition, when a similar method is used for a transmissive liquid crystal panel, there is an effect that visual recognition is possible under external light without providing a transflective film. In this case, assuming that the fine particles are dispersed on average, the light reflected by the fine particles can be regarded as having the same intensity as the light reflected through one-half of the film thickness of the color filter. . For this reason, the reflected light intensity of the light reflected by the fine particles is larger than the light reflected by the reflective film behind the color filter containing the fine particles. Therefore, there is not much difference between color reproducibility when using the backlight and color reproducibility when using the external light, and there is an advantage that it is bright when using the external light and dark when viewed using the backlight. Further, in the case where the transmitted light intensity is emphasized and the reflected light intensity is emphasized, it is only necessary to change the density of the fine particles, and there is an effect that it can be easily changed at a low cost.

  The liquid crystal display device of the present invention is included in a color filter, a substrate on which a color filter is formed, a counter substrate provided so as to face the substrate, a liquid crystal layer provided between the substrate and the counter substrate, and the color filter. It has fine particles that reflect light. With such a configuration, since the reflected light from the fine particles reaches the observer, a transflective display device can be realized without a transflective film.

  Further, a semi-transmission means for reflecting incident light at a predetermined ratio is provided between the color filter and the substrate. With such a configuration, the brightness at the time of reflection can be improved without sacrificing the transmittance of the light semi-transmissive means. At this time, as the semi-transmissive means, a reflective film having an opening for transmitting light or a dielectric multilayer film can be used.

  The fine particles are dispersed in the color filter. By providing dispersibility, the light reflected by the fine particles can be regarded as having the same intensity as the light reflected at one-half of the film thickness of the color filter, and a uniform brightness over the entire surface. can get.

  As fine particles, particles coated with silver-plated granular resin can be used. The diameter of this granular resin is preferably 30 to 70 nm.

  The configuration of the liquid crystal display device of this example is schematically shown in FIG. As shown in the figure, this liquid crystal display device has a configuration in which a nematic liquid crystal layer 6 is provided between a lower substrate and a counter substrate 5 facing the lower substrate, and an optical film 7 is disposed so as to sandwich both substrates. . The lower substrate has a structure in which a reflective film 3 having an opening is formed on a glass substrate 4 and a color filter 2 is formed thereon. The color filter 2 has three colored portions of RGB per pixel and uniformly contains fine particles 1 that reflect light. As fine particles 1, silver-plated granular resin having a diameter of about 30 to 70 nm was used. The optical film 7 is obtained by sequentially laminating a polarizing plate, a retardation film, a light scattering layer, and the like. This liquid crystal display device used STN mode driven by a passive matrix system.

  In this configuration, external light incident on the liquid crystal display device is not only mainly reflected at the non-opening portion of the reflective film 3 but also reflected by the fine particles 1 provided in the color filter 2. For this reason, constant reflected light due to the fine particles is visually recognized even in the pixel region corresponding to the opening of the reflective film 3. If the fine particles are dispersed on average, the light reflected by the fine particles can be regarded as having the same intensity as the light reflected through one-half of the thickness of the color filter. For this reason, the reflected light intensity of the light reflected by the fine particles is larger than the light reflected by the reflective film behind the color filter containing the fine particles. Therefore, a bright display as a whole can be visually recognized under the external light without changing the performance of the reflective film, that is, the opening area.

  The configuration of the liquid crystal display device of this example is schematically shown in FIG. This example is different from Example 1 in that a semipermeable membrane is not provided. Since the other parts are the same, the overlapping description is omitted.

  As shown in the figure, the present embodiment includes a lower substrate in which a color filter 2 is formed on a glass substrate 4, and the color filter 2 has a structure in which fine particles 1 that reflect light are uniformly included. is there. According to this configuration, part of the external light is reflected by the fine particles 1 existing in the color filter. Further, even when illuminated using a backlight, the light passes through the fine particles and is emitted to the viewer side, so that it can function as a semi-transmissive liquid crystal display device even though a semi-transmissive film is not formed. . Assuming that the fine particles are dispersed on average, the light reflected by the fine particles can be regarded as having the same intensity as the light reflected through one-half of the thickness of the color filter. Therefore, there is an advantage that there is not much difference between the color reproducibility of the transmissive display and the color reproducibility of the reflective display, the reflective display is bright, and the transmissive display can be viewed with a deep color. In addition, in the case where the transmitted light intensity is important and the reflected light intensity is important, it is only necessary to change the density of the fine particles, and the change can be easily performed at a lower cost than the case where the semi-transmissive reflective film is used. .

  The configuration of the liquid crystal display device of this example is schematically shown in FIG. This is an example when a semi-transmissive film such as a dielectric multilayer film that does not have an opening is used. Since other parts are the same as those in the first embodiment, the duplicate description is omitted. As shown in the figure, the lower substrate has a structure in which a dielectric multilayer film 8 is formed on a glass substrate 4 and a color filter 2 in which fine particles 1 that reflect light are uniformly present is formed thereon. . Here, a dielectric multilayer film 8 that reflects 50% of light and transmits 50% of light is used. According to this configuration, the external light incident on the liquid crystal display device is mainly reflected by the semi-transmissive reflective film 8, but partially passes through the color filter 2 and is also reflected by the fine particles 1. Regardless of the performance of the film 8, constant reflected light is visible. Therefore, in order to increase the reflected light, it is not necessary to change the setting so as to sacrifice the transmittance such that the transflective film reflects, for example, 70% and transmits 30%. Thus, the brightness at the time of reflection is improved while maintaining the brightness at the time of transmission, and a bright display can be visually recognized regardless of the surrounding conditions.

  In each of the embodiments described above, the STN mode that is driven by the passive matrix method is used. However, the present invention is not limited to this, and an active matrix liquid crystal panel that drives the pixel electrode by a switching element may be used. Further, any electro-optic effect mode such as a TN mode or an ECB mode can be used.

  As for the fine particles that reflect light, as long as they have the property of reflecting light, the shape is not limited to a spherical shape but may be a shape as well as a foil, a plate, a polyhedron, a hemisphere, and the like.

  Since bright display can be visually recognized using ambient light, which is ambient light, it can be applied to electronic devices that are desired to be used in various environments such as portable information devices. Furthermore, according to the present invention, since it is not necessary to change the performance of the semipermeable membrane, the present invention can be applied to an electronic device whose cost is reduced.

It is sectional drawing which shows the liquid crystal display device of this invention typically. It is sectional drawing which shows the liquid crystal display device of this invention typically. It is a figure which shows typically the cross-sectional structure of the liquid crystal display device based on 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fine particle 2 Color filter 3 Transflective film 4 Glass substrate 5 Opposite substrate 6 Nematic liquid crystal 7 Optical film 8 Dielectric multilayer film

Claims (7)

A substrate on which a color filter is formed, a counter substrate provided to face the substrate, and a liquid crystal layer provided between the substrate and the counter substrate,
The liquid crystal display device, wherein the color filter includes fine particles that reflect light.   2. The liquid crystal display device according to claim 1, wherein a semi-transmissive means for reflecting incident light at a predetermined ratio is provided between the color filter and the substrate.   The liquid crystal display device according to claim 2, wherein the semi-transmissive means is a reflective film having an opening that transmits light.   The liquid crystal display device according to claim 2, wherein the transflective means is a dielectric multilayer film.   The liquid crystal display device according to claim 1, wherein the fine particles are dispersed in the color filter.   6. The liquid crystal display device according to claim 1, wherein the fine particles are particles obtained by insulating coating a granular resin plated with silver.   The liquid crystal display device according to claim 6, wherein the granular resin has a diameter of 30 to 70 nm.

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