Color purity improving sheet, optical apparatus, image display, and liquid crystal display

Abstract

The present invention provides a highly practicable color purity improving sheet that while preventing unevenness in color and brightness from occurring, allows light with an improved color purity to be used for an image display efficiently and can improve color reproducibility of the image display. The color purity improving sheet includes a light-emitting layer which improves the purity of a color in a target wavelength range by absorbing light in a specific wavelength range other than the target wavelength range and converts the absorbed light to emitted light in the target wavelength range. The surface of the light-emitting layer on at least the light outgoing side is roughened so as to have an arithmetic average surface roughness Ra defined in JIS B 0601 (1994 version) in the range of 0.1 to 100 mum.

Description

[0001] Cross References to Related Applications [0002] This application claims priority from Japanese Patent Application No. 2007-14751 filed on January 25, 2007. The entire contents of this Japanese patent application are incorporated herein by reference. technical field [0003] The present invention generally relates to color purity improving sheets, optical devices, image display devices, and liquid crystal display devices. Background technique [0004] Recently, a liquid crystal display device in which light emitted from a light source device such as a cold cathode tube or a light emitting diode (LED) is controlled by a liquid crystal panel and thus forms an image has been developed and put into use. In the liquid crystal display device, in order to uniformly distribute the light emitted by the light source device on the entire display surface, a light guide plate is arranged on the optical path leading to the light source device, and it is parallel to the liquid cry...

AI Technical Summary

Problems solved by technology

[0007] However, in a conventional liquid crystal display device, colors between any two of R, G, and B (for example, yellow light of a wavelength band between the R wavelength band and the G wavelength band, and the G wavelength band and the B Light in the wavelength band between the wavelength bands) instead of R, G, and B are mixed in the emission spectrum of the cold cathode tube, and they are not sufficiently filtered out by the color filter

Therefore, there is a problem that color reproducibility deteriorates in display image quality

[0010] However, in the method in which the light guide plate or the light reflector may contain fluorescent substances, there is a problem that fluorescent substances exist in some areas and do not exist in other areas according to their positions in the light guide plate or light emitter, so that the intensity of the emitted light The wavelength distribution spectrum is not constant, which leads to unevenness in color

In addition, in the method of coating a fluorescent substance on, for example, the upper surface of a light guide plate, there is a problem that in-plane unevenness in luminance occurs

In addition, in both methods, the utilization efficiency of light converted with fluorescent substances is not high enough, and the color reproducibility of liquid crystal display devices cannot be considered to be sufficiently high

Moreover, the optical device lacks practicality because, for example, its configuration becomes complicated

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