JP3206534B2 - Color image forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus, and more particularly to a color image forming apparatus suitable for television broadcasting, image communication, medical use, industrial use, and theater use. It concerns the device. 2. Description of the Related Art Conventionally, a color image forming apparatus in which a color filter and a liquid crystal light valve are combined as a color image forming apparatus for selecting and displaying a light beam having a predetermined spectral characteristic from natural light or a light beam having a plurality of wavelength components. Is well known. FIG. 1 is a schematic view of a part of the configuration of an example of this type of color image forming apparatus. In the figure, reference numeral 1 denotes a white light beam from a multicolor light source S having a plurality of wavelength components,
The light flux 1 from the light is incident on a color filter unit 2 having three color filters of red (R), green (G), and blue (B) for each pixel spatially arranged to perform color separation. ing. The light valve section 3 composed of a plurality of light valves 3-1 provided for each color filter independently controls the intensity of transmitted light to perform gradation output and the like. As a typical color filter, an absorption type using a light absorbing material such as a dye or a pigment is widely used. In addition, as a light color filter, a filter using a multiple interference film, a diffraction grating, or the like is known. As liquid crystal light valves, there are known a TN (twisted nematic) type, a GH (guest / host) type, a birefringence control type, a phase transition type, a thermo-optic effect type and the like. In the conventional color image forming apparatus using a color filter and a light valve, three color filters R, G and B are spatially arranged as shown in FIG. Pixels are formed. For this reason, for example, the green component and the blue component of the white light (W) incident on the red filter portion (R) are removed by absorption, reflection, diffraction or the like, so that the light utilization efficiency is at most 1 / in principle.
It is about 3. Actually, this is multiplied by the transmittance of the light valve, and the light use efficiency is further reduced. SUMMARY OF THE INVENTION An object of the present invention is to provide a color image forming apparatus having high light utilization efficiency. In the color image forming apparatus of the present invention, one pixel is constituted by a plurality of light valves, and a plurality of light beams of different colors are formed by a plurality of light valves for each pixel. In a color image forming apparatus that forms a color image by adjusting the intensity, a unit that supplies parallel light, a spectral unit that divides the parallel light into a plurality of lights having different colors, and a common light source common to a plurality of light valves. A light-collecting element group in which a plurality of optical elements are arranged such that each light valve is located on their focal plane, and one of a plurality of lights having different colors from the spectral means is emitted from the vertical direction. By causing the remaining light to overlap and be incident on each common light-collecting element of the light-collecting element group from a plurality of directions inclined with respect to the vertical direction, the plurality of different colors are different for each common light-collecting element. the light It is characterized in that the light is condensed at different positions and is incident on the corresponding light valves. FIG. 2 (A) is a perspective view showing the basic structure of the present invention, and FIG. 2 (B) is a plan view schematically showing the operation of FIG. FIG. In the figure, reference numeral 1 denotes a white light beam having a plurality of wavelength components, 6 denotes a diffraction grating as a spectral unit for diffracting (split) the white light beam 1, and 5 denotes a plurality of light-collecting elements 5 having a refractive power in the diffraction direction of the diffraction grating 6. This is a light-collecting optical member (light-collecting element group) composed of -1 and is formed of a lenticular plate in this embodiment. Although the condensing optical member 5 is formed integrally with the diffraction grating 6, it may be formed independently. Reference numeral 3 denotes a light valve section in which a plurality of light valves are two-dimensionally arranged, and three light valves 3-1 to 3-2 in the horizontal direction.
3 make up one pixel. Reference numeral 7 denotes a diffusion plate which is formed integrally or independently of the light valve unit 3. In this embodiment, a white light beam 1 from a light source is incident on a lenticular plate 5 substantially perpendicularly. In this embodiment, a white light beam 1 from a polychromatic light source is condensed by a lenticular plate 5, and a zero-order, ±
The first-order diffracted light is guided to the light valve unit 3. In particular, in the present example, the light is guided to the light valve unit 3 by specifying the grating pitch, the amount of phase change, and the like of the diffraction grating 6.
Most of the energy is concentrated on the first-order diffracted light to improve the light use efficiency. As shown in FIG. 2 (B), the light valve section 3 is arranged such that each of the ± 1st-order diffracted light components such as red R, green G, blue B, etc. Three light valves 3 corresponding to at least one pixel in the column direction
They are arranged so as to enter 1, 3-2 and 3-3.
In a region not used as spectral light, for example, in a region where 0th-order diffracted light or ± 2nd-order or more diffracted light is concentrated, a light shielding plate for opaque light beams is arranged. Thus, 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, a description will be given using specific numerical values. In this embodiment, the diffraction grating 6 has a grating pitch of 1.2 μm.
m, a depth of 0.6 μm, a trapezoidal relief type having a ratio of peaks to valleys of 1: 2, a back surface of which is a lenticular surface, a pitch of one element of which is 600 μm, and integrally molded with polycarbonate. Used. The light valve 3 is made of TN liquid crystal and has a back surface as a diffusion surface 7. The light valve portion is arranged so as to obtain blue, green, and red light from the ridge of the lenticular plate 5 toward the valley. Then, one pixel is formed from the three light valves, and the zero-order diffracted light and ±
A light-shielding plate for shielding the second-order or higher order diffracted light is provided.
The three light valves 3-1, 3-2, and 3-3 have openings at positions where the peak wavelengths are 440 nm, 550 nm, and 620 nm and the bandwidths are ± 40 nm, ± 40 nm, and ± 30 nm, respectively. When the distance between the diffraction grating surface 6 and the light valve portion 3 is 0.5 mm, the blue opening is 200 μm, the green opening is 250 μm, and the red opening is 300 μm as viewed from the center of the ridge of the lenticular plate. Each light valve is installed centering on the position of. Wavelength 440 nm, 550 nm, 620 nm
When a fluorescent lamp having a color rendering property having a spectral peak is used, the conversion efficiency to the first-order diffracted light, that is, the light utilization efficiency from the light source to the light valve portion is about 70%, and the transmittance of the liquid crystal light valve is about 35%. %, And the light use efficiency of the entire system was about 20 several%. This is 4 to 5 times the light use efficiency of the conventional color image forming apparatus. In the example shown in FIG. 2, after the light beam passing through one element 5-1 of the lenticular plate 5 is diffracted by the diffraction grating 6,
Although the light is made incident on the area corresponding to the two pixel columns, for example, as shown in FIG. 3 (A), a light beam is made incident on the diffraction grating 6 from an oblique direction to use the −1st-order diffracted light, or B)
As shown in the figure, the grating of the diffraction grating 6 is asymmetrically shaped, so-called blazed, so that only the +1 order or −1 order diffracted light is used, and one element 5-1 of the lenticular plate 5 corresponds to one pixel column. The light may be incident on the region. For example, in the example shown in FIG. 3A, 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 a grating pitch of 0.6 μm, a depth of 2 μm, and a ratio of peaks and valleys. 1: 4 trapezoid, one element 5 of the lenticular plate 5
The pitch of 1 is 600 μm. When the distance between the diffraction grating 6 and the light valve unit 3 is 0.5 mm, the center position of the opening of the light valve is 120 μm for blue and 120 μm for green from the center of the ridge of one element of the lenticular plate 5. Is 230 μm and red is 300
It is set at the position of μm. A light-shielding plate is provided in other portions of the light valve, for example, except for the region where the -1st-order diffracted light is incident. The diffusion surface 7 (not shown) is located at a position about 0.5 mm away from the light valve section 3 to achieve a color image forming apparatus in which red, green, and blue separated lights overlap again to produce an arbitrary color by additive color mixing. I have. FIG. 6 is a schematic diagram showing the configuration of an example which is the basis of the present invention. In this embodiment, a lenticular plate 8 for projection and a lens 9 are written in place of the diffusion plate 7 in the example of FIG. The present invention is applied to a projection type color image forming apparatus in which a screen 10 is provided on an image forming surface provided on an emission side of a valve section 3. In the present invention, instead of the lenticular plate used in each of the above examples, a lens such as a so-called fly-eye lens or a selfoc lens in which a plurality of microlenses are arranged two-dimensionally is used, and passes through one microlens. Then, the diffracted light of a predetermined order that has been diffracted may be made incident on a region corresponding to at least one pixel. FIG. 5 is a schematic view of a main part of an embodiment of the present invention. In the figure, reference numeral 51 denotes a polychromatic light source close to a point light source.
The light beam from the light source 51 is incident on the diffraction grating 6 as a spectral unit by a collimator lens 52 as a parallel light beam. The diffraction grating 6 has the structure shown in FIGS. 2 (B), 3 (A) and 3 (B). Reference numeral 5 denotes a light-collecting element group, which includes a plurality of light-collecting elements. The light-collecting element group includes a lenticular plate, a fly's eye lens, a selfoc lens group, and the like. Reference numeral 3 denotes a light valve portion having a plurality of light valves, and has a structure shown in FIGS. 2, 3A, 3B and the like. In this embodiment, as compared with the example shown in FIG. 2, by disposing the diffraction grating 6 on the light source 51 side, reflected light from the diffraction grating 6 escapes to reduce stray light. Polychromatic light source
As 51, the light use efficiency and the color reproducibility are satisfactorily performed by using a light source having a high color rendering property in which light emission is concentrated in a specific wavelength range. In this embodiment, as shown in FIG. 5, the light valve section 3 is located at a position where the parallel light incident on the light-collecting element group 5 is condensed at one point, that is, at the focal plane of the light-collecting element group 5. Have been placed. At this time, as shown in FIG. 5, one of a plurality of lights having different colors from the diffraction grating 6 is incident on the light condensing element group 5 from the vertical direction. Further, as shown in FIG. 5, other plural lights are incident on the light-collecting element group 5 from plural directions inclined with respect to the vertical direction (not shown directly). As a result, light of different colors is condensed on each of the plurality of light valves arranged on the focal plane of the light condensing element group 5. The light valve in this embodiment may be any light valve as long as it can control light transmission. In addition to the above-described liquid crystal light valve, an electro-optic crystal, a thin film magnetic garnet, or the like may be used. Used, deformed mirror, EC (electrochromic)
A phenomenon utilizing a phenomenon or a PC (photochromic) phenomenon 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 condensed on the light valve surface is spatially separated by wavelength, and the color range that can be reproduced is determined by setting the wavelength region of the light valve opening corresponding to each color element. FIG. 4 shows the state of color reproduction at this time by CIE.
FIG. 3 is an explanatory diagram shown on a chromaticity diagram. In the figure, the region indicated by (a) is the wavelength 450 nm, 550 n of the spectrum light.
In this case, the center of one opening of the light valve is selected at a position corresponding to m, 620 nm. As the slit width of the opening is increased, the color reproduction range approaches the light source position P indicated by the arrow in FIG. Similarly, the area shown by (b) in FIG.
nm, 520 nm, and 650 nm.
Color reproduction is possible within the range surrounded by the solid line. In practice, the position is set in consideration of the position, the slit width, and the like according to the spectral distribution of the polychromatic light source. The light beam emitted from the light valve section 3 is processed variously depending on the form of the color image forming apparatus. For example, in the case of a direct view type, if a transmission type diffusion plate 7 is provided immediately after the light valve, an image can be observed. At this time, one surface of the light valve section 3 may be a diffusion surface. In the case of the projection type, the image may be projected on a screen by a projection system including a projection lens or a projection mirror and a Schmitt lens. The address of the image can be arbitrarily set, such as an electrical address or an optical address, according to the type of the light valve. In the above-described embodiment, it is preferable to install an optical member having a condensing power, for example, a Fresnel lens plate on the light source side of the lenticular plate, because the light flux from the light source can be effectively used. In this embodiment, a transmission type color image forming apparatus has been described, but a reflection type can also be used. According to the present invention, a bright color image forming apparatus can be achieved with high light use efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a conventional color image forming apparatus, FIG. 2 is a perspective view and a plan view of an embodiment of a color image forming apparatus on which the present invention is based, and FIG. FIG. 4 is an explanatory view of a spectral unit of the color image forming apparatus. FIG. 4 is an explanatory view of a color reproduction range in the color image forming apparatus of the present invention. FIG. 5 is an explanatory view of one embodiment of the present invention. Description of the system [Description of symbols] 1 White light beam 2 Color filter 3 Light valve unit 5 Lenticular plate 6 Diffraction grating 7 Diffusion plate 8 Projection lens 9 Lens 10 Screen

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification symbol FI // G02B 5/18 G02F 1/1335 530 27/00 G02B 27/00 (58) Fields surveyed (Int.Cl. ⁷ , DB G09F 9/00 G02F 1/13 G02F 1/13357 G02B 27/00

Claims (1)

(57) [Claims] In a color image forming apparatus that forms a color image by configuring one pixel with a plurality of light valves and adjusting the intensity of a plurality of lights having different colors from each other with the plurality of light valves for each pixel, parallel light is supplied. Means to
A light-splitting unit that divides the parallel light into a plurality of lights having different colors from each other; and a light-collecting element group in which a plurality of light-collecting elements common to a plurality of light valves are arranged such that each light valve is located on their focal plane. And a common light-collecting element group of the plurality of light-condensing elements from a plurality of directions inclined from the vertical direction with respect to one of the plurality of lights having different colors from the spectroscopic means. A color image, wherein the plurality of lights having different colors are condensed at different positions for each of the common light-collecting elements by being superimposed on an optical element, and are incident on the corresponding light valves. Forming equipment.