JPH0659260A - Light source for planar display panel - Google Patents

Abstract

PURPOSE:To obtain a light source capable of inexpensively coloring a planar display panel having an anisotropy substance layer where the transmission/non- trans-mission of light is controlled by driving impression voltage like a liquid crystal display device. CONSTITUTION:Incident light from side surfaces 5b, 6b in a horizontal direction are reflected on the slopes 5c, 6c of optical reflection plates 5, 6 whose cross section forms a tight angled triangle shape in a perpendicular direction, and two sheets of optical reflection plates 5, 6 are arranged so that whose slopes 5c, 6c are confronted with each other, and either one color light of three primary colors of red, green, blue respectively is incident on both side surfaces 5b, 6b and a bottom surface 5a side, and a mixed color light is emitted upward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source for a flat display panel such as a liquid crystal display device. More specifically, the present invention relates to a light source for a flat display panel of a color, which is capable of color display by using light sources of three primary colors of red (R), green (G) and blue (B) as a light source on the back surface side of the panel.

[0002]

2. Description of the Related Art There are various types of flat display panels such as liquid crystal displays (LCD) and electrochemical displays (ECD), all of which have low power consumption and are widely used. For example, liquid crystal displays (display devices) have characteristics of low power consumption and low voltage operation that are unmatched by other display devices, and are widely used for AV, personal computers, televisions, game machines, automobile instruments, and the like. Furthermore, colorization is required.

A color filter system, a twisted nematic system, a preochronic system, and the like have been considered for a conventional color liquid crystal display device, and a basic configuration of a color filter type which has been put into practical use is shown in FIG.

In FIG. 4, alignment layers 12 and 13 for forming a molecular alignment of liquid crystals are formed on both sides of a liquid crystal layer 11, and a transparent electrode 14 for forming electrodes of each segment is provided on one alignment layer 12 side. Further, RGB color filters 15, 16 and 17 are finely formed in a matrix corresponding to the display pixels, and typical array methods include mosaic, stripe, and triangular array. Normally, a black matrix 18 is formed between each pixel of the RGB color filters 15, 16 and 17 so that when viewed from the surface, it looks like a color similar to that of a liquid crystal surface to improve contrast and color purity. Further, a glass substrate 19 and a polarizing plate 20 are arranged on the upper surface. Further, on the side of the alignment layer 13 below the liquid crystal layer 11, a lower glass substrate 22 and a polarizing plate 23 are arranged via a transparent electrode 21, and a backlight 24 is further arranged below it. .

With this structure, light is emitted from the backlight and the alignment direction of the molecules of the liquid crystal layer 11 is adjusted in accordance with the voltage applied to the transparent electrodes 14 and 21 formed on both sides of the liquid crystal layer 11. Light from the light passes through the liquid crystal layer 11. The light transmitted through the liquid crystal layer 11 passes through red (R), green (G), and blue (B) RGB color filters 15, 16 and 17 according to each pixel, and is converted into red, green and blue colors, respectively. Depending on which pixel the light is emitted and the light passes through, the colors of adjacent lights are recognized as mixed colors, and color display can be performed.

[0006]

The above-mentioned color filter is composed of a light shield layer, a colored layer made of RGB, a protective film, and a common electrode. The dyeing method, pigment dispersion method, printing method, electrodeposition method or vapor deposition method is used. The colored layer is formed by a method or the like. Practical applications of this color filter are mainly the dyeing method and the pigment dispersion method, both of which are ×××××××
Since XX is used, the cost increases for large-scale products.
Therefore, the spread of conventional color flat display panels such as color liquid crystal displays has been delayed, and inexpensive flat display panels have been demanded.

In view of such circumstances, it is an object of the present invention to provide an inexpensive color light source for a flat display panel without using a color filter.

[0008]

In a light source for a flat display panel according to the present invention, a first light reflecting plate having a right-angled triangular cross section is arranged so that its inclined surface faces upward, and the first light reflecting section has a cross section. A second light reflecting plate having a similar shape to the cross section of the plate is arranged such that its slope faces the slope of the first light reflecting plate,
Reflective surfaces are formed on the slopes of the first and second light reflection plates so that light incident in a direction parallel to the bottom surface is reflected by the slopes in a direction perpendicular to the bottom surface. One of the three colors of red, green, and blue is incident on the side surface of the first light reflecting plate from the horizontal direction with respect to the bottom surface, and the side surface of the second light reflecting plate is parallel to the bottom surface. 3 above
The other one of the three colors is incident, and the remaining one of the three colors is vertically incident from the bottom surface of the first light reflecting plate.
It is characterized in that colors are incident and the three colors are emitted upward from the bottom surface of the second light reflecting plate.

Further, it is desirable that a semitransparent reflection film is formed on the bottom surface or the slope of the first light reflection plate.

Further, it is preferable that a light emitting diode (LED) is used as a light emitting source of three colors because the response speed is fast and the driving method is easy.

[0011]

According to the present invention, the inclined surface of the light reflecting plate is subjected to the reflection processing for reflecting the light incident from the lateral direction in the vertical direction, and the light incident from the three directions is combined at almost the same place.
An arbitrary color can be configured by using three primary colors of red (R), green (G), and blue (B) as incident light. By guiding the light as a light source to the back surface of each pixel of a flat display panel such as an LCD or an ECD, it is possible to colorize the flat display panel in combination with the light transmissivity by voltage driving of a liquid crystal layer or the like.

[0012]

The present invention will be described in detail with reference to the drawings. FIG. 1 (a) is a perspective view of a light reflecting plate 1 made of plastic or the like, which is one of the basic constituent elements of the present invention, and FIG. 1 (b) is a sectional explanatory view thereof. Bottom 1a
And the side surface 1b form a right angle, and a slope 1c is formed.

The angle θ of this slope is not particularly limited and is 0 to
The angle can be appropriately selected within the range of 45 °, but the smaller one is preferable in order to reflect the incident light efficiently and to save the space.

The slope 1c of the plastic plate 1 is shown in FIG.
As shown in (b), processing is performed so that the light incident from the side surface 1b is reflected upward. As an example of this process, for example, as shown in the sectional view of the inclined surface in FIG. 2A, the light P incident on the side surface 1b of the light reflection plate 1 in parallel to the bottom surface 1a is 45 ° on the inclined surface of the rectangular prism 1f. The slit 1d is formed so as to be incident at an angle of. If a plurality of slits 1d are formed, the light transmitted without being reflected by the first slit 1d is totally reflected by the next slope and goes upward, so that the light can be efficiently condensed.

The slits formed on the slope are shown in FIG.
As shown in (b), in the direction opposite to that of Fig. 2 (a) with respect to the bottom
When the 45 ° slit 1e is formed, the light P incident from the right side
The slit 1e becomes an inclined surface of the rectangular prism 1g and is reflected downward. The light that is transmitted without being reflected by the first slit 1e is totally reflected by the next slit and emitted downward, as in the case of FIG. 2A described above.

As the treatment of the inclined surface 1c which reflects light upward in the direction perpendicular to the bottom surface 1a of the light reflection plate, a diffusion material such as a transparent spray is used in addition to forming the slit forming an angle of 45 ° with respect to the bottom surface. It can also be obtained by applying or by roughening the surface to cause irregular reflection. The treatment of the inclined surface 1c of the light reflection plate 1 for reflecting the light upward may be performed only in the vicinity of the reflection portion where the light enters and is reflected by the inclined surface, or may be performed on the entire inclined surface 1c. .
Normally, the entire bottom surface of the light reflection plate is adjusted to the size of the pixel, and the entire surface is used.

The light reflecting plate 1 may be made of any material as long as it can easily transmit light and can be easily processed for reflecting light, and may be a glass plate or the like in addition to the plastic plate.

Next, the present invention in which the light reflecting plate is combined to form a color light source for a flat display panel will be described. FIG. 3 is a cross-sectional explanatory diagram of a color flat display panel that is an embodiment of the present invention.

In FIG. 3, reference numeral 5 denotes a first light reflecting plate, which is a slope 5 so that the light incident from the side surface 5b is reflected upward.
c is subjected to reflection processing. Therefore, the light A from the first light source that is incident from the right side surface 5b in FIG. 3 is reflected by the inclined surface 5c and emitted upward as described above. The second light reflection plate 6 is arranged on the slope 5c of the first light reflection plate 5 with a slight space 7 therebetween so that the slopes formed at the same angle face each other. It is preferable that a space 7 of about μm is formed between both slopes. The light reflection plate 6 is shown in FIG.
The light reflection processing as described in (b) is performed on the slope 6c, and the light B from the second light source incident from the side surface 6b is reflected by the slope 6c and is reflected toward the bottom surface 6a, that is, upward. The outer shape of the second light reflecting plate 6 is preferably the same as or similar to the outer shape of the first light reflecting plate 5. That is, in the case of a similar shape, the bottom surface 6a of the second light reflection plate 6 becomes parallel to the bottom surface 5a of the first light reflection plate 5, and the light directed upward goes straight without being refracted. is there. Further, when the light C is input from the side of the bottom surface 5a of the first light reflection plate 5, the light C is incident on the light reflection plate in a direction perpendicular to the light reflection plate. The light emitted from the second light reflecting plate 6 is emitted from the bottom face 6a of the second light reflecting plate which is parallel to the bottom face 5a of the first light reflecting plate, and thus becomes a light beam parallel to the incident light and travels upward.

Therefore, for example, the above-mentioned light A is red, light B
Is a green light and the light C is a light emitted from a blue light source, the three primary colors are mixed, and the light of any color is obtained by adjusting the intensities of the respective lights. By arranging a liquid crystal layer sandwiched by both electrodes on the bottom surface 6c of the second light reflection plate and driving a voltage between the liquid crystal layers, the directions of the liquid crystal molecules are unified or irregular, and Is transmitted or blocked, and when light is transmitted, by driving the light source, light of any color can be transmitted, and a color flat display panel is realized.

As the light source, for example, a semiconductor chip such as an LED is directly formed in the vicinity to emit light, or light is branched from a high power LED by an optical fiber or the like and guided to the light incident surface of the light reflecting plate. It can also be thrown in. Furthermore, O other than LED, such as EL and plasma displays
A light source having a fast response speed to N and OFF is preferably used.

The bottom surface 5 of the first light reflecting plate 5 in the above-described embodiment.
When a light-reflecting film is partially formed on a to form a semi-transparent film, the lights A and B incident from both sides are not reflected upward,
Even if there is light reflected downward, it can be effectively utilized by being reflected upward again by this bottom surface 5a. However, in this case, since the light C incident from the bottom surface side is reflected by about half, it is necessary to increase the light intensity in advance.

The semi-transparent film may be formed not on the bottom surface 5a of the first light reflecting plate 5 but on the slope 5c of the first light reflecting plate 5, but with the first light source. Since the third light source becomes weaker, it is necessary to increase the intensity of these lights in advance. Also, considering that light is reflected using such a semi-transparent film, the first light reflection may be performed without forming the reflection processing of the second light reflection plate in the reverse direction. The same plate is used as shown in FIG. 3, and the light C incident from the left side is reflected downward by the slope 6c of the second light reflection plate 6, and the reflected light is, for example, the first light. The light may be reflected upward by the semitransparent film formed on the bottom surface 5a of the reflector to concentrate the light upward.

[0024]

According to the present invention, it is formed of a thin plate material,
Light from three directions is concentrated in one direction by stacking light reflectors that reflect light in the right angle direction, so the red light on the three light sources,
By using the three primary colors of green and blue, it is possible to supply light of any color to each pixel of a flat display panel in which many small pixels are gathered like a liquid crystal display device. Therefore, there is an effect that a flat display panel for color display can be easily realized by combining with a monochrome panel whose light transmission and non-transmission is controlled according to a voltage applied to both ends like a liquid crystal layer.

Further, according to the present invention, since the color light source is directly used as the light emitting source without using an expensive color filter unlike the conventional color liquid crystal display device, it can be easily formed by, for example, an LED or the like. No backlight is required, and the manufacturing cost is low.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of a light reflecting plate used in a light source for a flat display panel that is an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of processing of a sloped surface in which light incident from the side is reflected in the vertical direction by a light reflecting plate that is an example of the present invention.

FIG. 3 is a schematic explanatory diagram of a light source for a flat display panel that is an embodiment of the present invention.

FIG. 4 is a cross-sectional explanatory view of a conventional color liquid crystal display device.

[Explanation of symbols]

 5 First Light Reflector 5a Bottom of First Light Reflector 5b Side of First Light Reflector 5c Slope of First Light Reflector 6 Second Light Reflector 6a Bottom of Second Light Reflector 6b Side surface of second light reflecting plate 6c Slope of second light reflecting plate

Claims (3)

[Claims] 1. A first light reflecting plate having a right-angled triangular cross section is arranged so that its slope faces upward, and a second light reflecting plate having a cross section similar to the cross section of the first light reflecting plate is formed. The slope is first
Is arranged so as to face the slope of the light reflection plate of
Reflective surfaces are formed on the slopes of the second light reflection plate so that light incident in a direction parallel to the bottom surface is reflected by the slopes in a direction perpendicular to the bottom surface.
From the horizontal direction to the bottom of the light reflector side red,
One of the three colors of green and blue is made incident, and the other one of the three colors is made incident on the side surface of the second light reflecting plate in a direction parallel to the bottom surface. A light source for a flat display panel, wherein the remaining one of the three colors is incident from the bottom surface of the reflection plate in a direction perpendicular to the bottom surface, and the three colors are emitted upward from the bottom surface of the second light reflection plate. . 2. The light source for a flat display panel according to claim 1, wherein a semitransparent film is formed on a bottom surface or a slope of the first light reflection plate. 3. The light source for a flat display panel according to claim 1, wherein each of the three colors of light is formed by a light emitting diode.