JPH01307790A - Lighting device for transmission type color image display device - Google Patents

Abstract

PURPOSE:To increase screen brightness by irradiating dots or stripes of fluorescent bodies of B, G, and R provided to a diffusion member with ultraviolet rays from a light source, converting them into visible light of B, G, or R, and irradiating an image display element directly with the converted light. CONSTITUTION:The image display element 12 is irradiated directly with light of B, G, or R by placing the diffusion member 11 consisting of fluorescent body dots or strips which converts the ultraviolet rays of 253.7nm emitted by the light source 9 into visible light in one of three wavelength ranges of 450+ or -50nm (B light), 530+ or -50nm (G light), and 630+ or -50nm (R light) for excitation and light emission above the light source 9 which emits the ultraviolet rays. Thus, the ultraviolet rays from the light source 9 are converted into the visible light of B, G, or R, which illuminate the image display element directly, so a color filter is not necessary. Consequently, the quantity of light is increased correspondingly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an illumination device that is disposed on the back side of a transmissive color image display device and illuminates the image display element from the back side.

2. Description of the Related Art An illumination device of a transmissive color image display device using an image display element such as a liquid crystal has a structure as shown in FIG. (For example, Tani et al., "High Definition Active Matrix Liquid Crystal Color Display," November 14, 1985, Television Society Technical Report ED905, etc.) In other words, a liquid crystal layer 2 is placed on top of a linear light source 1 using glasses 3 and 4. An image display element 7 having a structure in which polarizing plates 5 and 6 are placed between the glasses 3 and 4 is placed between the liquid crystal layer 2 and the glass 3, and blue (hereinafter referred to as B) and green (hereinafter referred to as B) are placed between the liquid crystal layer 2 and the glass 3. , G) and red (hereinafter referred to as R). (There is also a structure in which the color filter 8 is placed outside the polarizing plate 5.) .

In order to increase the color purity of the colored light from the color filter 8, the light source 1 has B and G filters as shown in FIG.

A three-wavelength region fluorescent lamp having spectral characteristics consisting of three R peak lights is used. In addition, the spectral transmission characteristics of the color filter 8 are as shown in FIG.
It has characteristics corresponding to each of the B, G, and R peak lights from.

The image display element 7 has a shutter function that changes its transmittance according to the image signal to be displayed and blocks the irradiation light from the light source 1, and changes in the transmittance of the image display element 7,
That is, the configuration is such that an image is presented by ON-OFF of transmitted light.

Problems to be Solved by the Invention In such a conventional illumination device, the transmittance of the image display element 7 is approximately 10% in the visible range, as shown in FIG.
~15%, and the transmittance of the color filter 8 is 11th
As shown in the figure, approximately 6 at each peak wavelength of B, G, and R.
Since it is about 0% to 80%, the light presented as an image through both the image display element 7 and the color filter 8 is 6% to 12% of the light emitted from the light source 1.

In recent years, one of the demands for using a transmissive color image display device outdoors or under bright illumination light is to increase the brightness of the screen (increase in brightness).

In order to realize this, the liquid crystal layer 2. Polarizing plates 5 and 6. What is necessary is to increase the transmittance of the color filter 8 or the like.

However, at the current level of technology, increasing the transmittance by a few percent would require a large amount of time and expense for technological development, so the general method for solving the above problems is to illuminate from the back of the transmissive color image display device. The current situation is to increase the amount of light (brightness) of the lighting device, that is, to use a large-capacity light source, or to use the light source with overload.

For this reason, lighting devices are always required to meet strict specifications.

Here, considering the condition of the inner surface of the bulb when a three-wavelength fluorescent lamp is used as the light source 1, here there is a B phosphor (e.g., europium-activated barium aluminate, magnesium: B IIL M g 2 AI 160
27; Eu2′″, etc.) and G phosphor (e.g., TVram activated cerium aluminate, magnesium: Ce M
Three types of phosphors are coated: g Al 1,01o; T b 3+, etc.) and R phosphor (e.g., europium-activated yttrium oxide: Y2O3; Eu3+, etc.), and the mixing ratio must be optimized. The light is emitted as white light.

There would be no problem if the B, G, and R phosphors were coated without interfering with (overlapping) each other, but due to the purpose of use, the phosphors are coated in multiple layers, so the visible light of each phosphor This includes the problem that the conversion efficiency to the light source decreases, and the luminous efficiency as a light source decreases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a lighting device that has high brightness, does not reduce the efficiency of using light from a light source, and does not cause color shift in emitted light.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
At the top of the light source that emits ultraviolet rays, a wavelength of 450 nm ± 50 nm is generated by 253.7 nm of the ultraviolet rays emitted from the light source.
nm (B light), 530nm±50nm (G light),
By placing a diffusion member consisting of a plurality of phosphor dots or stripes that excites and emits light by converting it into visible light in one of the three wavelength ranges of 630 nm ± 50 nm (R light),
B, G, and ordinary lights are used to irradiate the image display element.

action The effect of this technical means is as follows.

That is, the ultraviolet rays irradiated from the light source are irradiated onto the BGR phosphor dots or stripes provided on the diffusion member, and after converting this into any of the BGR visible light, an image is displayed. Since the element is irradiated directly, there is no need for a color filter, which not only increases the amount of light, but also increases the amount of light from B and G.

Since the R phosphors are arranged separately and independently in the form of dots or stripes, different types of phosphors do not overlap, and the luminous efficiency of the lighting device is improved.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram of a lighting device according to a first embodiment of the present invention, and FIG. 2 is a sectional view thereof.

In Figures 1 and 2, reference numeral 9 indicates a linear light source that emits ultraviolet light (for example, a germicidal lamp or a general fluorescent lamp that is not coated with phosphor and uses a quartz tube for the bulb). A reflecting member 10 that partially surrounds the light source 9, has a polyhedral cross-sectional shape, and is made of a material that efficiently reflects ultraviolet rays is provided below the light source 9.

On the other hand, above the light source 9, a diffusion member 11 is provided parallel to the tube axis direction of the light source 9, and further above the diffusion member 11, an image display element 12 is arranged close to and parallel to the diffusion member 11. ing. The diffusion member 11 is exposed to sunlight with a wavelength of 450 nm±50 nm and with a wavelength of 530 nm due to the excitation of ultraviolet rays.
G light with a wavelength of ± 50 nm and R light with a wavelength of 630 nm ± 50 nm.
The structure is such that a plurality of B, G, and R phosphor dots are arranged in a well-ordered manner on a glass plate, each of which is a phosphor that converts into any of the types of visible light to efficiently emit light.

The image display element 12 is a transmissive liquid crystal element whose transmittance changes according to the image signal to be displayed and has a shutter function to block the irradiation light from the light source 9. Change in transmittance, i.e. 0 of transmitted light
The configuration is such that an image is presented by N-OFF.

In the above arrangement, B and G of the diffusion member 11.

Of each phosphor dot of R, one dot is connected to image display element 1.
It is made to face one element of 2.

By configuring the lighting device as described above, as shown in FIG.
The remaining ultraviolet rays are reflected by the reflecting member 10 as reflected ultraviolet rays (indicated by a dashed line in the figure), and are then irradiated to the diffusing member 11. .

The diffusing member 11 has B, G, and R phosphor dots, and when this is irradiated with direct ultraviolet rays from the light source 9 and reflected ultraviolet rays from the reflecting member 10, mainly 253.
Sunlight, G light, and R light are excited and emitted from each dot by ultraviolet light having a wavelength of 7 nm, and the image display element 12 is irradiated with the light.

Here, as shown in FIG. 3, the emission spectrum of the phosphor dots of the diffusion member 11 has three wavelengths of B, G, and R. The spectral transmission characteristics of filters are optimized in the same way as when combined.

In the above configuration, both the direct ultraviolet rays from the light source 9 and the reflected ultraviolet rays from the reflecting member 10 are irradiated onto the diffusing member 11 . Diffusion member 11 is for B and G.

Since a plurality of R phosphor dots are arranged in a well-ordered manner, each phosphor dot emits sunlight and G light.

R light is constantly irradiated. B is applied to the image display element 19 by opening only the element of the image to be displayed among the image display elements 19 facing these (maximizing the transmittance by the shutter function).

A color image based on a combination of G and R will be presented.

By adopting such a configuration and characteristics, a color filter becomes unnecessary, and not only can the amount of light (screen brightness) be increased by that amount, but also the light source 9 and the diffusion member 1
By arbitrarily selecting the type of phosphor using only a combination of phosphor dots 1 and 1, the image display element 12 receives B light with high color purity.

It can irradiate G light and R light.

Furthermore, since the B, G, and FL phosphors are arranged separately and independently in the form of dots or stripes, different types of phosphors do not overlap, and the luminous efficiency of the lighting device is improved.

Next, a second embodiment of the present invention will be described based on the accompanying drawings.

FIG. 4 is a block diagram of a lighting device according to a second embodiment of the present invention, and FIG. 5 is a sectional view thereof.

Note that the lighting device of the second embodiment shown in FIGS. 4 and 5 basically has the same configuration as the lighting device of the first embodiment shown in FIGS. 1 and 2. Identical components are given the same numbers and detailed explanations will be omitted.

What differs from the configuration of the first embodiment in FIGS. 4 and 5 is that a light matching member 13 is arranged behind the diffusion member 11 and the image display element 12. This optical matching member 1
3 is composed of a plurality of micro Fresnel lenses 14 and a light shielding plate 15, as shown in FIG.
1 micro Fresnel lens per 1 dot of phosphor
4 correspond to each other, and one element of the image display element 12 corresponds to these.

Usually, the visible light emitted from the phosphor of the diffusion member 11 is
The direction of the irradiation is not constant and is diffused. For this reason,
If the image display element 12 is a transmissive liquid crystal element, even if the above-mentioned light is irradiated onto the image display element 12, it will be irradiated perpendicularly or nearly perpendicularly to the image display element 12 due to the incident angle characteristics. The light incident on the image display element 12 easily enters the image display element 12, but the more oblique the light is, the more difficult it is for people to enter the image display element 12.
There is a possibility that color shift may occur or shutter function may deteriorate, that is, image quality may deteriorate due to leakage light.

The light matching member 13 solves this problem, and the irradiated light from the diffusing member 11 is focused and the direction of irradiation is matched by the micro Fresnel lens 14 of the light matching member 13, and then efficiently irradiated onto the image display element 12. be done. Moreover, the light shielding plates 15 are B and G.

It has the role of separating the irradiated light from each phosphor dot of R so that they do not interfere with each other.

By configuring the lighting device as described above, it is possible to not only efficiently irradiate the image display element 12 with light from the diffusion member 11 but also prevent light leakage, so that a high-brightness, high-quality transmitted image can be displayed. can do.

In the second embodiment, a micro Fresnel lens was used as the optical matching member 13, but instead of the micro Fresnel lens, a distributed refractive index lens, an optical fiber, a light guide, a filter with a light control function, etc. may be used. It has a similar effect.

Next, a third embodiment of the present invention will be described based on the accompanying drawings.

The first embodiment and the second embodiment are both inventions regarding a bright device used in a so-called direct view type image display device that displays an image on an image display element as it is.
This embodiment relates to an illumination device for a so-called projection type image display device that enlarges and projects an image on the image display device.

FIG. 7 is a block diagram of a lighting device according to a third embodiment of the present invention, and FIG. 8 is a sectional view thereof.

In FIGS. 7 and 8, 16 is a linear light source that emits ultraviolet light (for example, a germicidal lamp or a general fluorescent lamp that is not coated with phosphor and uses a quartz tube for the bulb). A reflecting member 1 partially surrounding the light source 16 and made of a material that efficiently reflects ultraviolet rays is provided at the bottom of the
There are 7.

On the other hand, a diffusing member 18 is provided above the light source 16 in parallel to the tube axis direction of the light source 16, and an image display element 19 is arranged above the diffusing member 18 in close proximity to and parallel to the diffusing member 18. ing. Furthermore, a projection lens 20 is arranged in front of the image display element 19 to enlarge and project the image of the image display element 19 forward.

The diffusion member 18 is made of glass coated with a phosphor that converts the excitation of ultraviolet light into visible light and efficiently emits light.
It consists of three separate and independent phosphor screens: a B phosphor screen, a G dose light surface, and an R type light surface.

An image display element 19 consisting of a plurality of elements is arranged for one phosphor screen of each of the B, G, and R phosphor screens. It is a transmissive type liquid crystal element whose transmittance changes and has a shutter function to block the irradiated light from the light source 16.The image display element 19 displays an image by changing its transmittance, that is, by turning the transmitted light ON-OFF. It is structured to present.

In the above configuration, as shown in FIG. 8, both the direct ultraviolet rays from the light source 16 (indicated by the broken line in the figure) and the reflected ultraviolet rays from the reflective member 17 (indicated by the dashed line in the figure) irradiate the diffusion member 18. be done. Since the diffusion member 18 has separate and independent phosphor screens for B, G, and R, the B, G, and R lights are constantly irradiated from each phosphor screen. Of the image display elements 19 facing these, if only the element of the image to be displayed is opened, 8 images, 0
The image is displayed on the image display element 19 as an R image. By combining these images using the projection lens 20 and projecting them forward, B, G, and R color images are presented.

With such a configuration, a color filter is not required, and the image display element 19 receives B light with high color purity, only by the combination of the light source 16 and the fluorescent screen of the diffusion member 18.
Not only can G light and R light be irradiated, but the projection lens 20 can enlarge and project an image to an arbitrary size.

Furthermore, each phosphor screen of the diffusion member 18 only needs to be coated with a single phosphor, and different types of phosphors do not overlap as in conventional three-wavelength fluorescent lamps.

Luminous efficiency as a lighting device is improved.

In addition, due to its high color purity and good luminous efficiency,
Problems such as color shift and insufficient screen brightness that occur when projecting an enlarged image can be overcome.

Although the first, second, and third embodiments do not describe in detail the type of phosphor to be applied to the phosphor dots, stripes, or phosphor screen, rare earth type light If the substance has an emission spectrum in a relatively narrow band such as a body (for example, a phosphor used in a three-wavelength fluorescent lamp or a phosphor used in a CRT (cathode ray tube) display such as a color television), Not particularly limited.

In addition, although an example in which a liquid crystal element is used as an image display element has been described, an electrochromic element (ECD) or an electro-optic ceramic element (PLZT) may be used instead of a liquid crystal element.
The same effect can be obtained by using any device that can arbitrarily vary the light transmittance (blocking and opening), such as a device using a mechanical shutter mechanism.

Effect of the invention The present invention has the following effects.

(1) The ultraviolet rays irradiated from the light source were irradiated onto the B-GR phosphor dots or stripes provided on the diffusion member, and this was converted into visible light of B-light, G-light, or R-light. Afterwards, since the image display element is directly irradiated with the light, a color filter becomes unnecessary, and the amount of light (screen brightness) increases accordingly.

(2) B and G light with high color purity can be achieved by simply selecting the type of phosphor by combining the light source and the phosphor dots or stripes of the diffusion member.

The image display element can be irradiated with R light.

(3) Since the B, G, and R phosphors are arranged separately and independently in the form of dots or stripes, different types of phosphors do not overlap, and the luminous efficiency of the lighting device is improved.

(4) By arranging the light matching member in the darkness between the image display element and the diffusion member, the light from the diffusion member can be efficiently irradiated to the image display element, so that a high-brightness, high-quality transmitted image is displayed. can do.

(5) The diffusion member is a phosphor screen for B and a phosphor screen for G.

By dividing the R phosphor screen into three, placing an image display element in front of each phosphor screen, and combining the B, G, and Ft images and projecting them forward as an enlarged image using a projection lens,
Images can be displayed on a large screen.

(6) Due to high color purity and good luminous efficiency,
This overcomes problems such as color shift and insufficient screen brightness that occur when projecting an enlarged image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a lighting device according to a first embodiment of the present invention, FIG. 2 is a sectional view of a lighting device according to a first embodiment of the present invention, and FIG. FIG. 4 is a diagram of the emission spectrum of the phosphor of the diffusion member in the lighting device according to the embodiment, FIG. 4 is a configuration diagram of the lighting device according to the second embodiment of the present invention, and FIG. 6 is a sectional view of a light matching member in a lighting device according to a second embodiment of the present invention, and FIG. 7 is a configuration diagram of a lighting device according to a third embodiment of the present invention. , FIG. 8 is a sectional view of a lighting device according to a third embodiment of the present invention, and FIG. 9 is a configuration diagram of a conventional lighting device.
FIG. 10 is a spectral characteristic diagram of a light source in a conventional lighting device.
FIG. 11 shows the spectral transmission characteristics of a color filter in a conventional illumination device, and FIG. 12 shows the spectral transmission characteristics of an image display element in a conventional illumination device. 9.16... Light source, 10.17... Reflective member, 11
．． 18... Diffusion member, 12.19... Image display element, 13... Optical alignment member, 14... Micro Fresnel lens, 15... Light shielding plate, 20... Projection lens. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2 111--Reflection frequency line @ Figure 3 Wavelength (nrn) Figure 4 10 Reflective member Figure 5 =- --- 1 direct beam outside the tree ← - 1 Mataya Hayabusa outside line 6 Figure 7 Hongai Tanuki Figure 7 R light 17 Also shoot member Figure 8 R 9 G light - 111 Direct line outside line 11 Ittomo defeating Hayabusa Gaikon Figure 9 迭罷尝Figure 10 Fountain length (nm) Figure 11 Fountain -+ (rt punishment

Claims (3)

[Claims] (1) A light source that has the maximum radiation power at a wavelength of 253.7 nm among ultraviolet rays, and a light source that partially surrounds this light source,
a reflecting member that reflects part of the ultraviolet rays from the light source onto a diffusing member; a diffusing member that is provided above the light source and emits light by the ultraviolet rays directly irradiated from the light source and the ultraviolet rays reflected from the reflecting member; an image display element provided on the upper part of the diffusing member and having a shutter function to block the irradiated light from the diffusing member;
Multiple phosphor dots or stripes that excite and emit light by converting it into visible light in one of three wavelength ranges: ±50nm (blue: B), 530nm ±50nm (green: G), and 630nm ±50nm (red: R) An illumination device for a transmissive color image display device comprising: (2) In the illumination device for a transmissive color image display device according to claim 1, between the image display element and the diffusing member, parallel light and parallel light of the light emitted from the diffusing member are provided. An illumination device for a transmissive color image display device in which a light matching member is arranged to allow only irradiated light to enter an image display element. (3) In the illumination device for a transmissive color image display device according to claim 1, the diffusion member is composed of three types of separate and independent phosphor screens: a blue phosphor screen, a green phosphor screen, and a red phosphor screen, An illumination device for a transmissive color image display device, in which an image display element is arranged above each diffusion member, and a projection lens for projecting an image from the image display element to a predetermined position is arranged in front of the image display element. .