JPS62293222A - Color display device - Google Patents

Abstract

PURPOSE:To obtain a color display device characterized by high light utilizing efficiency, low power consumption, hight brightness, and excellent color reproducibility by utilizing a diffraction grating and a light valve. CONSTITUTION:White light beams 1 radiated from a polychromatic light source are condensed by a lenticular plate 5 and the 0-th order, + or -1st order ...diffracted beams are respectively led into the light valve part 3 through the diffraction grating 6. A large part of energy is concentrated into the + or -1st order diffracted beams led into the light valve part 3 by specifying the grating pitches of the diffraction grating 6, a phase change value, and so on. The light valve part 3 is arranged so that spectrum beams of red R, green G and blue B components of respective + or -1st order diffracted beams are made incident upon three light valves 3-1-3-3 corresponding to at least one picture element in the train direction of one picture element train in an area distributing the spectrum beams and a douser to interrupt the transmission of the light beams is arranged on area for concentrating the 0-th order diffracted beams or + or -1st order or more diffracted beams.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a color display device, particularly a color display device suitable for television broadcasting, image communication, medical use, industrial use, theater use, etc. This invention relates to display devices.

(Prior Art) Conventionally, a combination of a color filter and a liquid crystal light valve has been well known as a color display device that selects and displays a light beam having predetermined spectral characteristics from natural light or a light beam having multiple wavelength components. ing. FIG. 1 is a schematic diagram of a portion of the configuration of an example of this type of color display device. In the figure, 1 is a white light beam from a polychromatic light source S having a plurality of wavelength components. ),
Color separation is performed by making the light incident on a color filter part 2 having three color filters of blue (B). And a plurality of light valves 3-1 provided for each color filter.
Color reproduction, gradation, etc. are performed by independently controlling the intensity of transmitted light using the light valve section 3 consisting of the following.

A typical color filter is an absorption type that uses light absorbing materials such as dyes and pigments, and is widely used. Color filters using multiple interference films, diffraction gratings, etc. are known as color filters that select colors by changing the traveling direction of this light guide.

As liquid crystal light valves, there are known types such as TN (twisted nematic) type, GH (guest host) type, birefringence control type, phase change type, and thermo-optic effect type.

These conventional color display devices using color filters and light valves spatially display red and
Three color filters R, G, and B of green and blue are arranged to form one pixel. For this reason, for example, the green and blue components of the white light (W) incident on the red filter part (R) are removed by absorption, reflection, or diffraction, so the light utilization efficiency is in principle only within reach. .

In reality, this is multiplied by the transmittance of the light valve, further reducing the light utilization efficiency.

The spectral characteristics of a color filter also depend on the type of dye, the structure of the multilayer film, or the amount of phase modulation of the diffraction grating (height of the grating, etc.)
However, in reality, the spectral characteristics deviate considerably from the ideal spectral characteristics, making it difficult to obtain good color reproducibility.

In addition, in conventional color display devices, three different color filters must be manufactured for each pixel in the size of one pixel, which is very difficult in terms of manufacturing process, manufacturing time, yield, etc.

(Problems to be Solved by the Invention) The purpose of the present invention is to provide a color display device that uses a diffraction grating and a light valve to have high light utilization efficiency, low power consumption, brightness, and excellent color reproducibility. shall be.

(Means for Solving the Problem) A pixel consisting of a diffraction grating, a condensing optical member consisting of a plurality of condensing elements having refractive power at least in the diffraction direction of the diffraction grating, and a plurality of light valves is one-dimensional or two-dimensional. A plurality of light valve parts arranged in a row are arranged so that diffracted light of a predetermined order that has passed through the diffraction grating and one condensing element of the condensing optical member is directed to an area corresponding to at least one pixel of the light valve part. By controlling the transmitted light intensity of a plurality of light valves corresponding to each pixel, the wavelength of the transmitted light is selected and color display is performed.

Other features of the invention are described in the Examples.

(Embodiment) Fig. 2(A) is a perspective view of an embodiment of the present invention, Fig. 2(B) is a perspective view of an embodiment of the present invention.
) is a plan view schematically showing the operation of FIG. In the figure, 1 is a white light beam having a plurality of wavelength components, 6 is a diffraction grating that diffracts in a one-dimensional direction, and 5 is a condensing optical system consisting of a plurality of condensing elements 5-1 having refractive power in the diffraction direction of the diffraction grating 6. It is a member, and in this embodiment, it is composed of a lenticular plate. Although the converging optical member 5 is constructed integrally with the diffraction grating 6, it may be constructed independently. 3 is a light valve section in which a plurality of light valves are two-dimensionally arranged, and three light valves 3-1.3-2.3-3 in the horizontal direction constitute one pixel. Reference numeral 7 denotes a diffusion plate, which is constructed either integrally with the light valve section 3 or independently.

In this embodiment, the white light beam 1 from the light source is transmitted to the lenticular plate 5.
is incident almost perpendicularly to

In this embodiment, a white light beam 1 from a polychromatic light source is condensed by a lenticular plate 5, and transmitted through a diffraction grating 6 to 0 rays, ±1st order...
The diffracted lights are guided to the light valve section 3. In particular, in this embodiment, by specifying the grating pitch, phase change amount, etc. of the diffraction grating 6, the light is guided to the light valve section 3 by ±1.
Most of the energy is concentrated in the next diffracted light.
Efforts are being made to improve light usage efficiency.

As shown in FIG. 2(B), the light valve section 3 is arranged in at least one pixel in the column direction of one pixel column in the region where spectrum lights such as red R1 green G and blue B of the ±1st order diffracted light are distributed. The light is arranged so as to be incident on three corresponding light valves 3-1.3-2.3-3. In areas that are not used as spectral light, for example, areas where 0th-order diffracted light and ±2nd-order or higher diffracted light are concentrated, a light shielding plate is placed to prevent the light beam from passing through.

Accordingly, in this embodiment, the wavelength of the transmitted light is selected by controlling the intensity of the transmitted light passing through each light valve.

Next, it will be explained using specific numerical values.

In this embodiment, the diffraction grating 6 has a diameter of 1.2 μm. It consists of a trapezoidal relief mold with a depth of 0.5 μm and a peak-to-valley ratio of 1.2, the back side of which is a lenticular surface, and the pitch of the elements is 600 μm, which is integrally molded with polycarbonate. There is.

The light valve 3 is made of TN crystal and has a diffusion surface 7 on the back surface.

The light valve portion is arranged so as to obtain colored light of portrait, green, and red from the ridge of the lenticular plate 5 toward the valley. Three light valves form one pixel, and a light shielding plate is provided in the gap between the three light valves to shield zero-order diffracted light and ±second-order or higher diffracted light. 3-1.3-2
．． The three light valves in 3-3 have a peak wavelength of 440n.
m.

Bandwidth is ±40nm at 550nm and 620nm
, ±40 nm, and ±30 nm.

The distance between the diffraction grating surface 6 and the light valve section 3 is 0.
When the diameter is 5 mm, the blue opening is 200 μm and the green opening is 250 μm when viewed from the center position of the ridge of the lenticular plate.
In the red opening, each light valve is installed centered at a position of 300 μm.

When using a color-rendering all-light lamp with spectral peaks at wavelengths of 440 nm, 550 nm, and 620 nm, the conversion efficiency to first-order diffracted light, that is, the light utilization efficiency from the light source to the light valve section, is about 70%, and the liquid crystal The transmittance of the light valve is approximately 35%, and the light utilization efficiency as a whole system is about 20%.
Met.

This is 4-5% compared to the light usage efficiency of conventional color display devices.
It's double.

In the embodiment shown in FIG. 2, one element 5- of the lenticular plate 5
1 is diffracted by a diffraction grating 6, and then incident on an area corresponding to two pixel rows.
), a light beam is incident on the diffraction grating 6 from an oblique direction to utilize the 11th order diffracted light, or the grating of the diffraction grating 6 is made into an asymmetrical shape, so-called blazed, as shown in FIG. 6(B). Alternatively, only the +1st order or 11th order diffracted light may be used and one element 5-1 of the lenticular plate 5 may be made to enter an area corresponding to one pixel column.

For example, in the embodiment shown in FIG. 3 (8), the angle of incidence of the light beam 1 on the lenticular plate 5 is 30 degrees, the shape of the diffraction grating 6 is such that the grating pitch is 0.6 μm, the depth is 2 μm, and the peak-to-valley ratio is 1: 4
It has a trapezoidal shape, and the pitch of one element 5-1 of the lenticular plate 5 is 600 μm.

When the distance between the diffraction grating 6 and the light valve part 3 is 0.5 mm, the center position of the opening of the light valve is 120 μm from the center of the ridge of one element of the lenticular plate 5 for blue color.
m, 230 μm for green color, and 300 μm for red color.

A light shielding plate is provided in other parts of the light valve, for example, in areas other than the area where -1st-order diffracted light is incident.

The diffusion surface 7 (not shown) is approximately 0.5 mm from the light valve portion 3.
A color display device is achieved in which the separated red, green, and blue lights overlap again to produce any color by additive color mixture.

FIG. 6 is a schematic diagram of another embodiment of the present invention. In this embodiment, a lenticular plate 8 for projection and a lens 9 are used in the light valve section 3 instead of the diffuser plate 7 of the embodiment shown in FIG. The arrangement is applied to a projection type color display device in which a screen 10 is arranged on the image forming plane on the emission side.

In the present invention, a so-called fly's eye lens or selfoc lens in which a plurality of microlenses are arranged two-dimensionally is used instead of the lenticular plate used in each of the above embodiments. The diffracted light of the order may be made to enter an area corresponding to at least one pixel.

Note that when the polychromatic light source used in this example is close to a point light source,
For example, as shown in FIG. 5, it is preferable that the light beam from the light source 51 is made into a parallel light beam by a collimator lens 52 and made incident on the diffraction grating 6.

In this embodiment, compared to the embodiment shown in FIG. 2, the diffraction grating 6 is placed closer to the light source, thereby allowing reflected light from the diffraction grating to escape to the outside, thereby reducing stray light. Further, as the polychromatic light source, it is preferable to use a light source with high color rendering properties that concentrates light emission in a specific wavelength range from the viewpoint of light utilization efficiency and color reproducibility.

The light valve in this embodiment may be of any type as long as it can control light transmission, and in addition to the above-mentioned liquid crystal light valve, an electro-optic crystal, a thin film magnetic garnet, etc. may be used. things, things using deformed Milani, EC (electrochromic) phenomenon and pC
(Photochromic) phenomenon or the like may be used.

The arrangement position and opening area of the light valve are determined by the required color reproduction range. That is, the first-order diffracted light focused on the light valve surface is spatially separated by wavelength, and the reproducible color range is determined by which wavelength region the opening of the light valve corresponding to each color element is set.

FIG. 4 is an explanatory diagram showing the state of color reproduction at this time on a CIE chromaticity diagram. In the figure, the region indicated by (a) has a wavelength of 450 nm in the spectrum of light.

This is a case where the center of one opening of the light valve is selected at a position corresponding to 550 nm and 620 nm.

As the slit width of the opening increases, the color reproduction range approaches the light source position P indicated by the arrow in the figure. Similarly, in the region shown in (b) of the same figure, the center of the opening is set to a wavelength of 480 nm, 52 nm.
This is the case where the wavelength is set to 0 nm and 650 nm, and color reproduction is possible within the range surrounded by the solid line. In reality, the slits are installed with careful consideration of the position, slit width, etc. that match the spectral distribution of the polychromatic light source.

The light flux emitted from the light valve section 3 is processed in various ways depending on the form of the color display device. For example, in the case of a direct view type, if a transmission type diffuser plate 7 is provided immediately after the light valve, images can be observed. In this case, one side of the light valve section 3 may be used as a diffusion surface. In the case of a projection type, the image may be projected onto a screen using a projection system consisting of a projection lens or a projection mirror and a Schmidtler.

The image address can be arbitrarily set, such as an electrical address or an optical address, depending on the type of light valve. □ In each of the above embodiments, it is preferable to install an optical member having a light-converging power, such as a larynel lens plate, on the light source side of the lenticular plate, since this makes it possible to effectively utilize the luminous flux from the light source.

Although the present embodiment shows a transmissive type color display device, a reflective type can be used as well.

(Effects of the invention) ゛According to the present invention, by using a diffraction grating and a light valve, instead of using three color filters as in the past, colored light with high light utilization efficiency and predetermined spectral characteristics can be obtained. This makes it possible to achieve a bright color display device with excellent color reproducibility.゛

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional color display device, Figure 2 (A)
, (B) are respectively a perspective view and a plan view of one embodiment of the power→-display device of the present invention, FIG. FIG. 4 is an explanatory diagram of the color reproduction range in the color display device of the present invention, and FIGS. 5 and 6 are explanatory diagrams of other embodiments of the present invention. In the figure, 1 is a white light beam, 2 is a color filter, 3 is a light valve part,
5 is a lenticular plate, 6 is a diffraction grating, 7 is a diffuser plate, 8 is a projection lens, 9 is a lens, and 10 is a screen.・ □ Patent Applicant: Canon Co., Ltd. No. 4, No. 5, Ward No. G Utsute-Jonne City JF 'f-4-:: (Voluntary) 2. Title of invention color display device 3. Amendment person case and Relationship Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4, Agent's residence Address: 301 Jiyukaoka, Belheim, 2-17-3 Okusawa, Taya-ku, Tokyo 158 (Telephone: 718-5614)
) (1) Column for detailed explanation of the invention in the specification (2) Column for brief explanation of drawings in the specification → 6. Contents of amendment (1) (a) " depth 0.5μm
" is corrected to "depth 06 μm". '-' (0) "For projection" on page 1, page 1, line 11 of the specification is corrected to "for projection". (c) "Projection type" in the third line of page 13 of the specification is referred to as "projection type";"projectionlens" is referred to as "projection lens"; and "projection mirror" in the fourth line of the same specification is referred to as "projection mirror". "Projection system" in the fifth line is corrected to "projection system". (2) (A) "Lens for projection" from line 13 to line 14 on page 14 of the specification is "lens for projection"
and correct it.

Claims (2)

[Claims] (1) A light in which a plurality of pixels are arranged one-dimensionally or two-dimensionally, each consisting of a diffraction grating, a condensing optical member consisting of a plurality of condensing elements having refractive power in at least the diffraction direction of the diffraction grating, and a plurality of light valves. The bulb section is arranged such that diffracted light of a predetermined order that has passed through the diffraction grating and one condensing element of the condensing optical member is incident on a region corresponding to at least one pixel of the light valve section, and each of the above-mentioned 1. A color display device characterized in that a color display is performed by selecting the wavelength of passing light by controlling the transmitted light intensity of a plurality of light valves corresponding to pixels. (2) The color display device according to claim 1, wherein a region on which the zero-order diffracted light of each pixel of the light valve section is incident is an opaque section.