JPS60130715A - Color display device - Google Patents

Abstract

PURPOSE:To obtain a color display device which has high color purity and superior color reproducibility by using a light source which has a light emission peak in the main wavelength region of transmission spectral characteristics of each color element of a color filter. CONSTITUTION:An R, a G, and a B color filters 1 are arranged corresponding to respective fine picture elements of a liquid-crystal optical shutter 6. Luminous flux from a three-wavelength light emitting fluorescent tube which has a light emission peak in the main wavelength region (R, G, B) of transmission spectral characteristics of the filters 1 is passed through a optical guide plate 8 made of transparent resin to obtain plane luminous flux, which is incident to the color filters 1 through a liquid-crystal shutter 6, obtaining a sharp image with high color purity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color liquid crystal display device comprising a light shutter, a color filter having wavelength selective transmittance in the visible wavelength range, and a light source.

As shown in FIG. 1, a color display device capable of displaying full color is composed of a light shutter 2 equipped with a color filter 1 and a light source 3, and visually recognizes light 4 modulated by display information. 5 is a reflecting plate. Due to their construction, most transmission types place the light source behind the all-light shutter, but reflective types, in which the light source is placed in front of the original shutter, are also possible. The color filter and original shutter are shown in Figure 2 (a) and (b).
As shown in (a) in the case of additive color mixing, B (red), G (green), and B (blue) are dispersed in the entire plane, and (b) in the case of subtractive color mixing, C (cyan), Y ( yellow) and M (magenta) are arranged one on top of the other. The second method also uses a color filter and its modulated light shutter to attenuate unnecessary wavelength regions of the light source light, and performs total spectral synthesis corresponding to the color and brightness to be displayed.

Usually, the color filter used here is one that utilizes the wavelength-selective transmittance of dyes or pigments, but as shown in FIG. 3, the transmittance characteristics are broad, making it difficult to reproduce colors with high color purity. A comparison of the color range with a color CRT (cathode ray tube) is shown in Figure 4. In this x, 1 color system, the farther the coordinates are outside the horseshoe shape, the more pure the color becomes, closer to monochromatic light.

Furthermore, the range surrounded by the triangle connecting the three primary colors of Moon, G, and B represents the color range that can be theoretically synthesized from these three primary colors. From this point of view, making the triangle as large as possible improves color reproducibility. In the case of a color CRT (broken line in FIG. 4), good color reproducibility is obtained because of the sharp spectrum of light emitted by the phosphor. On the other hand, since color filters use the light absorption of dyes and pigments, the transmission spectrum tends to be broader than that of luminescent displays (Figure 3), and the color range is limited as shown in the line in Figure 4. I end up. Furthermore, when dyes and pigments that satisfy heat resistance and light resistance are selected, color purity further decreases and the color range is also limited.

The present invention was devised in view of these drawbacks, and an object of the present invention is to provide a color display device with high color purity and excellent color reproducibility that cannot be obtained using dyes and pigments alone.

The basic concept of the present invention is to obtain primary colors with high color purity by providing the emission spectrum of the light source so as to complement the transmission characteristics of the color filter, even if the transmission characteristics of the color filter remain broad. .

This principle will be explained in more detail.

FIG. 5 shows an example of the spectral characteristics of the light source used in the present invention. For R, G, and B filters, a light source with sharper Rp, Gp, and Bp peaks is used.

This light source is RP, GP and B so that it appears white.
The pi is adjusted. For example, in the case of G, the spectrum after passing through the filter has a narrower band than the spectrum of the light source. The broken lines in Figure 5 are R, G, and B after passing through the filter.
E indicates primary colors. As a result, even if the color purity of each color element of the color filter is not high, the characteristics of the light source are reflected and the color purity of transmitted light is improved.

Therefore, the new design concept of the present invention, in which a white light source is synthesized from the peak emission of three primary colors, and the peak emission characteristics of the three primary colors are combined with the transmission characteristics of all color filters, makes it possible to reproduce dramatically brighter colors.

A similar theory holds true for subtractive color mixing systems.

This is because the additive color system is limited to the Oka wavelength range, G wavelength range, and B wavelength range. The component t- is the difference that is sequentially subtracted, and the emission spectrum of the original light source is R
If the peak emission occurs in a narrow band in the wavelength range, G wavelength range, and B wavelength range, the transmitted light will be close to narrow band monochromatic light even if it is a subtractive mixture of Y/O-M. Because it will be.

The present invention will be explained in detail below with reference to Examples.

FIG. 6 shows the entire emission spectrum of a three-wavelength band type fluorescent tube. It can be seen that sharp peak light emission occurs in the R, G-B wavelength region. FIG. 7 shows the entire spectrum after the light source system shown in FIG. 6 has completely passed through the color filter shown in FIG. The dashed-dot line represents R, the solid line represents G, and the broken line represents B.

When three-wavelength band type fluorescence/U-sound is used, as shown in FIG. 7, sharp peak light is emitted even after passing through a color filter, and it is perceived as three primary colors with high color purity.

The peak emission wavelength of a three-wavelength emission type fluorescent tube can be changed depending on the phosphor used, but in order to obtain white color, it is necessary to use 610.540.4 that corresponds to the FT, G, and B wavelength ranges.
It has an emission peak around 50 nm.

FIG. 8 shows the color ranges of various light sources in a system using the color filter of FIG. 3. The solid line is a three-wavelength band type fluorescent tube, and the broken line is a 7-calcium phosphate white fluorescent tube, and a single-dot chain H*c.

The figure shows the case where the Jf, Jf, and C light sources are used. As is clear from this, a simple white fluorescent tube has a small color range and poor color reproducibility. Furthermore, compared to a standard C light source with a broad spectrum, the color range is greatly expanded by using a three-wavelength fluorescent tube as the light source.

As an example of this application, FIG. 9 shows a color display device using a liquid crystal optical shutter (2) using the electro-optic effect of liquid crystal, a three-wavelength band type fluorescent tube, and a light guide plate 0 made of a transparent resin.

The liquid crystal optical shutter has an array of minute pixels, and the R and G colors correspond to each pixel.

A B color filter ■ is installed. The light beam from the three-wavelength fluorescent tube passes through the light guide plate, becomes a surface light source, and enters the liquid crystal light shutter and color filter. Since the liquid crystal optical shutter controls the amount of transmitted light according to image information, the emitted light (2) is colored, achieving full-color display. In this example, since a three-wavelength band type fluorescent tube is used as the light source, an extremely vivid full-color image can be reproduced, as explained with reference to FIG.

FIG. 10 shows the relative emission spectrum when a three-wavelength band type CRT is used as the light source. It can be seen that the peak light emission corresponds to the R wavelength range, G wavelength range, and B wavelength range. This is a phosphor for color television, such as P22.
This is achieved by mixing and applying (JEDEC) or by arranging minute R, G, and B point light sources that are equal to or smaller than a pixel. The broken lines in Figure 10 indicate El, G,
It shows the spectrum of the B primary color after passing through a color filter. In this way, when a CRT that emits R, G, and B light is used as a light source, it is possible to make the transmitted light spectrum narrower than the transmission characteristics of the color filter shown in Figure 3.
Three primary colors with high color purity can be obtained. Also this CR
Since T only needs to emit light from the entire surface, scanning with an electron beam is sufficient, and fbD, highly accurate convergence, and focus are not required. Figure 11 shows a flat type C that emits R, G, and B light.
This is a liquid crystal color display device that uses RT■ as a light source. R9
The G and BJiJ light bodies are mixed and coated on the face plate (■), making it a white surface light source. Since this light th5i has the emission spectrum shown in FIG. 10, it is possible to reproduce vivid colors by synergistically with the wavelength selectivity of the color filter as described above.

Internal light emitting [CL devices can also be used as R, G, B light emitting devices. As an example, distributed exchange K
The case of L device will be explained. As shown in Table 1, Z
By mixing a dopant with an n S -based phosphor, R, G, and B light emission is possible.

First, a dispersion WKL device was used in which these phosphors and dopant were dispersed in a high dielectric constant material (for example, cyano, ethyl, cellulose, etc.), and the structure was sandwiched between electrodes on both sides. A light source having peaks in the R, G, and B wavelength regions can be obtained by blending the phosphor and the dopant in a specific blending ratio from those shown in Table 1.

The KL″jt sources thus obtained are R,G.

As with the case of B-emission CRT, color reproducibility is superior to that of a light source with a flat spectrum.

FIG. 12 is a cutaway diagram when r, , go (light emitting diodes) are used as light sources. The LEDs are arranged in an array t' in order to obtain brightness and to avoid a large amount of wiring. LJnD uses the five types shown in Table 2 that emit R, G, and B light.

As shown in FIG. 12, these light beams are converted into a surface light source by color mixing 11 and light guide @, o by the light diffusing plate (2), and enter the liquid crystal light shutter (2) as white light. The liquid crystal light shutter has R,
G and B color filters are installed for each pixel to display a full-color image.

The light emitted by the LED has the emission spectrum shown in Figure 15, so when combined with the transmission characteristics of the color filter shown in Figure 4, the effective VC3C6 will emit light in a narrower band, resulting in improved color purity and color reproduction range. Expanding.

FIG. 14 shows an example in which a low-speed electron beam excitation fluorescent tube is used as the light source. The phosphor shown in Table 6 is blended on the inner surface of the face plate (■) which is the source of the image, to obtain a white surface light source.

As shown in FIG. 14, the fluorescent tube is excited by low-speed electron beams, and the thermionic electrons from the filament (2) are accelerated by the electrode (2), which excites the fluorescent substance on the inner surface of the face plate. Basically, it has the same structure as a fluorescent display tube.

The entire emission spectrum of this light source is shown in FIG.

By combining this with the transmission characteristics of the color filter shown in FIG. 3, the R, G, and B emission bands are further narrowed, and color purity and color reproducibility are expanded.

As described above, in the present invention, the transmission spectrum of the color filter is further narrowed by the emission spectrum of the entire light source, thereby improving color purity and color reproducibility. Therefore, R,G,
B-light emitting bodies may be arranged in a plane and mixed with a light diffusing plate or the like to produce white light, or a method may be used in which light emitters are blended to emit R, G, and 'B mixed light.

Furthermore, although the explanation has been made regarding all light sources having emission peaks in R, G, and B, the present invention can also be applied to monochromatic or multi-color color display devices. For example, if you want to switch the display between yellow and black, the 15th
It is sufficient to have the transmission characteristics shown by the broken line in the figure. Furthermore, if a light source whose peak emission wavelength matches the dominant wavelength of the transmission characteristic is used (as shown by the broken line in FIG. 15), the spectrum of the visible light becomes even narrower than when a color filter is used alone. As a result, the color purity is excellent and a colorful display can be obtained.

Furthermore, optical shutters are mainly liquid crystal electro-optical devices (
For example, we have explained the electro-optic effect of crystals (for example, lead titanate, zircon The present invention is also applicable to optical shutters using mechanical rotation or movement.

Further, the present invention is effective as long as the type of light source complements the entire transmission spectrum of the color filter, and light sources other than those in the above embodiments may be used.

As described above, the present invention compensates for the narrow band recirculation characteristic of the color filter by using a light source whose emission peak exists in the main wavelength region corresponding to the transmission spectrum of the color filter. As a result, not only high color purity and excellent color reproducibility are obtained, but also broad characteristics of color filter dyes and pigments are tolerated, so highly reliable and low-cost products are used. I can do it,
It also has the effect of completely improving the reliability of color display devices and reducing costs. The new color display device design method according to the present invention is highly effective in the field of full-color image displays that require excellent color reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a general color display device. (a
) is a case of a transmission type, and (b) is a case of a reflection type. FIG. 2 is a configuration diagram of a color display device for additive color mixing (a) and subtractive color mixing (b). Figure 3 shows the transmission characteristics of typical F, G, and E color filters. Is Fig. 4 the color range in OIB, xy chromaticity diagram? It represents. The solid line is the color range of a typical color filter,
The dashed line is the color range of a typical color CRT. Figure 5 shows the emission characteristics of the light source used in the present invention (solid line) and the emission characteristics of the three primary colors E, C-, and B after passing through the color filter (
(dashed line) is fully shown. FIG. 6 is an example of the emission spectrum of a three-wavelength band type fluorescent light source. Figure 7 shows the light source using the three-wavelength region type fluorescent tube shown in Figure 6.
The spectral characteristics after passing through the color filter 4 having the transmission characteristics shown in FIG. 3 are shown. FIG. 8 shows the color range when the color filter shown in FIG. 3 and various light sources are combined. The solid line is a three-wavelength range emission type fluorescent tube, the broken line is a white fluorescent tube, and the one-dot chain line is the color range when an O/JO light source is used. FIG. 9 is a perspective view of a color display device using a three-wavelength band type fluorescent tube and a liquid crystal optical shutter. FIG. 10 shows the relative emission vector (solid line) of a three-wavelength band emission type CRT and the emission spectrum (broken line) of the three primary colors RlG and B after passing through a color filter. FIG. 11 is a perspective view of a liquid crystal color display device using a three-wavelength band type CRTf light source. FIG. 12 is a cutaway diagram of the liquid crystal color display device t in the case of using an all-LED light source. FIG. 13 shows the emission spectrum of the LED used. FIG. 14 is a cutaway diagram of a liquid crystal display device using a fluorescent tube excited by slow electron beam as a light source. FIG. 15 shows the emission spectrum of a fluorescent tube caused by low-speed electron beam excitation. Figure 16 shows the transmission spectrum of the yellow color filter (
(solid line) and the emission spectrum (dashed line) of a yellow light source. (b) Day 1 (aJ) (b) Figure 2 To Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 Figure 9 Figure (Regulation J Figure 10 Figure 11 Figure 1 Cow Figure 15 Figure 16 Country

Claims (8)

[Claims] (1) In a color display device consisting of a light shutter that controls the amount of transmitted light, a color filter consisting of multiple color elements, and a light source, a light source having an emission peak in the dominant wavelength region of the transmission spectral characteristics of each color element of the color filter is used. A color display device characterized by: (2) A color display device characterized in that the color display device uses a light source having emission peaks in red, blue, and green wavelength regions. (3) The color display device according to any one of claims 1 to 2, wherein the optical shutter is an electro-optical device using liquid crystal. (4) The color display device according to any one of claims 1 to 3, characterized in that the color display device uses a fluorescent discharge tube manufactured by a three-wavelength generator as a light source. (5) The color display device according to any one of claims 1 to 5, characterized in that the color display device uses a cathode ray tube as a light source. (6) The color display device according to any one of claims 1 to 3, characterized in that the color display device uses an electroluminescent element as a light source. (7) The color display device according to any one of claims 1 to 6, characterized in that the color display device uses a light emitting diode as a light source. (8) Claims 1 to 3 are characterized in that the color display device uses a slow electron beam excited fluorescent tube as a light source.
Color display device according to item 3.