JPH11296098A - Backlighting type display device, light guide device used for the same, and manufacture of light guide device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a backlighting type display device which can be increased in luminance efficiency when a display part is backlighted by using a light guide plate, a light guide device used for it, and a manufacturing method of the light guide device. SOLUTION: The light guide device 14 guides the light from a light source unit 11 to the display part 12 and a white film 16 which prevents internal light from leaking to the circumference is formed on the circumferential surface of a transparent plate 15 and made white, so that light of all the wavelength of the visible light of the transparent plate 15 can be reflected by the border surface between the white film 16 and transparent plate 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back-illuminated display device which emits light, such as predetermined characters and marks, in a button switch or a display panel of an automobile or various devices, and a light guide used therein. The present invention relates to a device and a method for manufacturing a light guide device.

[0002]

2. Description of the Related Art In the field of automobiles, for example, operation information of accessories such as a radio reception frequency and a set temperature of an air conditioner is usually displayed in a center portion of a dashboard where operation parts of various accessories are provided.

[0003] Here, in a car, there is a case where it is necessary to operate in a dark room when driving at night, so that it is necessary to display information while illuminating the display unit from the back surface.

Conventionally, as shown in FIG. 2, illumination light from a light source unit 1 such as an LED or a bulb (vacuum tube) is illuminated from a back surface onto a display unit such as a button switch 2 or a display panel (not shown). In addition, light is transmitted through the light-transmitting holes 3 having the shape of characters, symbols, and the like hollowed out in the display portion (2), and the display is performed by making the shape of the light-transmitting holes 3 stand out.
In this case, since the light source unit 1 and the display unit (2) are often arranged at a fixed distance from each other, a transparent light guide plate 4 using a translucent resin such as acryl is provided between them. Interposed, the light emitted from the light source unit 1 is guided in the light guide plate 4 and illuminates the light transmitting holes 3 of the display unit (2).

[0005]

However, since the light guide plate 4 conventionally used is formed using only a transparent resin such as transparent acryl or the like, the peripheral surfaces 4a and 4b of the light guide plate 4 are formed. Some of the light leaked out of the device, and the luminance efficiency could not be said to be the best due to light loss.

Accordingly, an object of the present invention is to provide a back-illuminated display device capable of increasing the luminance efficiency when back-illuminating the display unit using a light guide plate, a light guide device used therefor, and a light guide device. It is to provide a manufacturing method.

[0007]

Means for Solving the Problems In order to solve the above problems,
The present invention is a back-illuminated display device that illuminates illumination light from a predetermined light source from a back surface to a predetermined display unit, and displays the display content of the display unit by using the illumination light, Between the light source and the display unit, in a back-illuminated display device in which a light guide device that guides light from the light source to the display unit is interposed, the light guide device travels by repeating total reflection. A transparent plate that guides internal light from the light source side to the display unit side, and is formed on all surfaces except the light incident surface facing the light source side and the light exit surface facing the display unit side of the transparent plate. A white film for preventing light traveling in the transparent plate from leaking in the peripheral direction.

Here, at the time of manufacturing the light guide plate, a first step of forming the transparent plate and a second step of forming and integrating the white film immediately after the first step are performed. Through this, efficient production can be performed.

[0009]

FIG. 1 is a perspective view showing a back-illuminated display device according to one embodiment of the present invention. As shown in FIG. 1, the back-illuminated display device illuminates the display unit 12 with illumination light from a predetermined light source unit (light source) 11 from the back, and displays or displays the display light in the display unit 12 with the illumination light. The display is such that the shape of the engraved predetermined character or symbol is raised and displayed, and in particular, a light guide plate (light guide device) 14 is interposed between the light source unit 11 and the display unit 12. .

Here, the light source unit 11 has a light emitting element such as an LED or a bulb (vacuum tube) mounted on a predetermined circuit board, and is housed in a light-shielding protective case 11a having an open front. .

The display section 12 is formed by forming a light-transmitting hole 13 cut out in a predetermined character or symbol shape in a light-shielding body such as a button switch or a display panel. Preferably, a colored translucent body is inserted.

The light guide plate 14 is made of a transparent plate 15 made of a transparent resin such as acrylic as in the prior art.
And a white layer film (white film) 16 for preventing leakage of light traveling inside in the peripheral direction.

Here, the white film 16 is a white film formed by mixing a white pigment into acrylic or the like similar to the transparent plate 15 or a resin of a different material from the transparent plate 15 or the like. The coating is applied to all surfaces 15c and 15d of the plate 15 other than the light incident surface 15a facing the light source unit 11 and the light emitting surface 15b facing the display unit 12 side. In FIG. 1, for convenience of explanation, the white film 16 is omitted from the side surface 15 d of the transparent plate 15 so that the end surface of the transparent plate 15 is exposed. A film 16 is formed. Thus, the transparent plate 15
Since the white film 16 formed on the surfaces 15c and 15d around is white, light of all wavelengths of visible light traveling in the transparent plate 15 is transmitted at the boundary between the white film 16 and the transparent plate 15. reflect. Thereby, the loss of visible light in the light guide plate 14 can be reduced as much as possible.

According to a general two-color molding method, the light guide plate 14 is formed by first molding a transparent plate 15 using a predetermined mold or the like, and then immediately forming the white film 16 using another mold or the like. It is molded and integrated.

A method of preventing light in the transparent plate 15 from leaking to the outside by covering the light with a metal plate, a mirror plate, or the like can be considered. In this case, after the transparent plate 15 is formed, the transparent plate 15 is formed. Is transported to another process and then covered with a metal plate, a mirror plate, or the like, which limits the efficiency of the manufacturing process. On the other hand, in the back-illuminated display device of this embodiment, when the light guide plate 14 is formed, the transparent plate 15 is first formed in accordance with the two-color molding method, and then the white film 16 is formed immediately thereafter to be integrated. By doing so, the processing speed in the production process can be reduced.

In the back-illuminated display device having the above-described structure, the light-emitting elements in the light source unit 11 emit light, and light is emitted from the light incident surface 1.
The light enters the transparent plate 15 of the light guide plate 14 through 5a. Then, total reflection is repeated inside the transparent plate 15, the light is emitted from the light emitting surface 15 b, illuminates the display unit 12 from behind, and the shape of the light transmitting hole 13 (characters, symbols, etc.) is transmitted by the light passing through the light transmitting hole 13. ) To the viewer.

Here, of the light traveling inside the transparent plate 15, the light traveling at an angle with respect to the traveling axis direction is:
When it reaches the surrounding surfaces 15c and 15d, it tries to leak out from here.

However, the surface 15 around the transparent plate 15
Since the white film 16 is formed on c and 15d, light of all wavelengths of visible light traveling in the transparent plate 15 is reflected on the boundary surface between the white film 16 and the transparent plate 15 and becomes transparent. Board 15
Will be returned inside. Thereby, the light guide plate 14
The loss of visible light inside can be reduced as much as possible.

In the back-illuminated display device according to the above-described embodiment, a light-transmitting hole 13 such as a character or a symbol is formed in the display unit 12, and an image is projected by transmitting the light-transmitting hole 13. However, the area of the light transmitting hole 13 may be made opaque or cloudy light diffusion state, and the other area of the display unit 12 may be made transparent. Further, at least the light transmitting hole 1 of the display unit 12 is provided.
Coloring may be performed by covering the area 3 with a color filter. Alternatively, in place of displaying characters or the like by the light transmitting holes 13, for example, an image is displayed by irradiating light from the back surface, such as a transmission liquid crystal display element, a light transmission hologram display element, or a transmission FLCD. Any type may be used.

[0020]

According to the first aspect of the present invention, a light guide device for guiding light from a light source to a display unit is provided on a peripheral surface of a transparent plate to prevent leakage of internal light in a peripheral direction. Since the white film is formed, the white film formed on the surface around the transparent plate is white, so that light of all wavelengths of visible light traveling in the transparent plate is converted to the white film and the transparent plate. Can be reflected at the boundary surface. Therefore, the loss of visible light in the light guide plate can be reduced as much as possible.

Here, it is conceivable to prevent the light in the transparent plate from leaking to the outside by covering it with a metal plate, a mirror plate, or the like. In this case, once the transparent plate is formed, the transparent plate is separated. According to the light guide plate according to the second and third aspects of the present invention, there is a limit to the efficiency in the manufacturing process because the metal sheet or the mirror plate covers the plate after being conveyed to the process. When a transparent plate is first formed in accordance with the two-color molding method at the time of the production of a white film, then a white film is formed and integrated immediately thereafter, so that the processing speed in the production process can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a back-illuminated display device according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a conventional back-illuminated display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Light source unit 12 Display part 13 Light transmission hole 14 Light guide plate 15 Transparent plate 16 White film

Claims (3)

[Claims] 1. A back-illuminated display device that illuminates illumination light from a predetermined light source to a predetermined display unit from a back surface, and displays the display content of the display unit by using the illumination light. In a back-illuminated display device in which a light guide device that guides light from the light source to the display unit is interposed between the light source and the display unit, the light guide device progresses by repeating total reflection A transparent plate that guides the internal light from the light source side to the display unit side, and is formed on all surfaces of the transparent plate other than the light incident surface facing the light source side and the light emitting surface facing the display unit side. And a white film for preventing light traveling in the transparent plate from leaking in the peripheral direction. 2. The light guide device used in the back-illuminated display device according to claim 1, wherein the white film is formed and integrated on a peripheral surface of the formed transparent plate. A light guide device characterized by being formed. 3. The method for manufacturing a light guide device according to claim 2, wherein the first step of forming the transparent plate and the white film are formed and integrated immediately after the first step. A method of manufacturing a light guide device, comprising: