JPH08320417A - Display panel - Google Patents

Abstract

PURPOSE: To provide a display panel using an illumination light guide capable of accomplishing the surface illumination with luminance as uniform as possible at a low cost. CONSTITUTION: As for the display panel with the illumination light guide for emitting light incident from one end face of a flat light guiding member 3 in a direction nearly perpendicular to the incident light by scattering and reflection, a light source 2 installed on the end face so as to generate the incident light and an illumination object to which the surface illumination is applied with the emitting light, the illumination light guide is constituted by installing a light reflecting means 4 on the side face opposite to the light emitting side face of the member 3 so as to consecutively increase the reflectivity of light as it goes away from a light incident point along the direction of the incident light.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display panel provided with an illumination light guide capable of surface illumination. Since it is difficult to make the brightness uniform in the conventional surface illumination using the light guide, research on the illumination light guide and the display panel using the same that can obtain the surface illumination as bright as possible up to the end. Was requested. 2. Description of the Related Art An acrylic resin plate is used for a display panel for displaying switch positions of devices and for guiding operations, and a reflective film is coated on the side opposite to the illumination surface of the acrylic plate or The use of a roughened illumination light guide is known as shown in FIG. In the display panel shown in FIG. 3, the acrylic plate 1 is used as it is as a guide for illumination light, and guides the light 10, 14, 15 from the light source 2 such as a tungsten bulb to the right. Light 13
Indicates that the light 10 is totally reflected on the illumination side in the acrylic plate 1. On the other hand, the light 13, 1 incident on the reflection film 12
Numerals 4 and 15 are scattered / reflected by the reflection film 12, and out of the scattered light, outgoing lights 16, 17 and 18 which are directed to the illumination side 11 serve as illumination light for illuminating the characters on the acrylic plate 1 as described above. [0004] In FIG. 3, the light source 2
Since the light from the light is guided to the right and travels, the light after being scattered is emitted from the back surface side to the illumination side 11, 16, 17,
18 gradually decreases in the order of 17, 16 and 18, and the right side suddenly becomes dark. Further, since all the light from the light source 2 does not enter the acrylic plate 1, there is a drawback that the utilization rate of the light from the light source 2 is low. When a light emitting diode is used as the light source 2, the light emitting direction can be limited to increase the utilization rate, but there is a drawback that the light source is expensive. Further, even if a scattering surface is processed and adjusted instead of the reflection film 12, the same result is obtained. It is an object of the present invention to provide a display panel using an illuminating light guide that solves the above-mentioned drawbacks and obtains surface illumination with as uniform brightness as possible at low cost. FIG. 1 is a perspective view showing the structure of the present invention. As shown in FIG. 1, an illumination light guide that emits light incident from one end surface of the flat light guide member 3 in a direction substantially perpendicular to the incident light by scattering and reflection, and the incident light is generated. Light source 2 provided on the end surface for
The present invention has the following configuration in a display panel having an illumination target that is surface-illuminated by the emitted light. That is, in the illumination light guide, the reflectance of the light continuously increases on the side surface of the member opposite to the light emission side surface as the distance from the light incident point increases along the direction of the incident light. The light reflection means 4 is provided and comprised. FIG. 2 is a top view seen from above in FIG.
This will be described below with reference to FIGS. Since the light guide guide member 3 is planar and the light source 2 is placed on one end face thereof, the light entering the light guide guide member 3 from the light source 2 is scattered and reflected in the guide member 3. , Is emitted to the upper left of FIG. Therefore, in FIG. 1, the surface 5 is illuminated by the light 8 and 9 emitted from the surface 5 on the side opposite to the surface on which the reflecting means 4 is provided by the light reflecting means indicated by the step 4. In FIG. 2, light rays 6 and 7 are directed toward the surface on which the light reflecting means 4 is attached, and light ray 10 is directed toward the emission surface. As shown in FIG. 1, the light reflection means 4 is provided on the side surface of the light guide guide member 3 opposite to the light emission side surface, and the light is reflected as the distance from the light incident point increases along the direction of the incident light. The reflectance is configured to continuously increase. Therefore, even if the emitted light 9 is separated from the light source 2, the reflectance does not become small, and the display panel in which the brightness of the irradiation surface 5 is spatially uniformized is obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The notches 4 shown in FIGS. 1 and 2 show an example of a concrete structure of a light reflecting means, which is formed by repeating peaks and valleys on the surface of the light guide member 3. As the distance from the light source 2 increases, the intervals between the ridges and valleys become smaller. Therefore, relatively less light is reflected from the inside of the guide member 3 closer to the light source 2, and some light is emitted from the guide member 3 in the direction opposite to the illumination side, but is reflected in the guide member 3 as the distance from the light source 2 increases. The amount of light emitted is relatively large. The amount of light from the emission surface does not decrease even if the distance from the light source 2 increases. Therefore, in the display panel using the above-mentioned light guiding guide member 3, the brightness of the irradiation surface 5 is substantially uniform over the entire surface from a position near the light source 2 to a distance. Forming the guide member 3 from a synthetic resin is effective for mixing the fluorescent substance and for exhibiting the following structural features. In particular, it is preferable to use polycarbonate resin or methacrylic resin as the material. When a fluorescent substance is mixed, the incident light is reflected by the fluorescent substance and immediately becomes emitted light, so that the brightness of the surface 5 as the display panel becomes brighter. If a halogen lamp having an emission wavelength peak in the visible light region is used as the illumination light source 2, the conversion efficiency of fluorescence is improved and the fluorescent color becomes brighter. Furthermore, if a white light source with a color filter is used as the light source 2, the color tone can be easily changed. As described above, according to the present invention, the light guide means is provided with the light reflecting means for continuously changing the reflectance of light according to the distance from the incident point. Since the surface on the side opposite to the side on which the reflecting means is attached is effectively illuminated, the reflectance does not decrease at the position away from the light source, and the emitted light is effectively obtained. Therefore, it is possible to obtain a display panel capable of surface illumination with substantially uniform illuminance. Further, it is possible to easily form a display panel in which the illuminance of surface illumination is increased by mixing a fluorescent substance or the like.

[Brief description of drawings] FIG. 1 is a perspective view showing a configuration of the present invention. FIG. 2 is a top view of FIG. 1 viewed from above. FIG. 3 is a diagram showing a conventional configuration. [Explanation of symbols] 2 light sources 3 Light guide member 4 ticks 5 Illuminated surface 9 Outgoing light

Claims (1)

[Claims] 1. A guide for illumination light that causes light incident from one end face of the flat plate-shaped light guide guide member to be emitted in a direction substantially perpendicular to the incident light by scattering / reflection, and provided on the end face for generating the incident light In a display panel having a light source and an illumination target which is surface-illuminated by the emitted light, the illumination light guide is provided on a side surface opposite to the light emission side surface of the member,
A display panel, characterized in that a light reflection means is provided so that the reflectance of the light continuously increases as the distance from the light incident point increases along the direction of the incident light. 2. The display panel according to claim 1, wherein the light guide member is made of a polycarbonate resin or a methacrylic resin. 3. The light source is a halogen lamp having an emission wavelength peak in the visible light range.
Display panel according to item. 4. The display panel according to claim 1, further comprising a color filter for changing a color tone of the emitted light.