JP3410579B2 - Projection type color image display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type color image display device of a single plate type for performing color display by one liquid crystal display element without using a mosaic color filter,
In particular, the present invention relates to a projection type color image display device applied to a compact projection type color liquid crystal television system or information display system.

[0002]

2. Description of the Related Art A conventional projection display device will be described. Since the liquid crystal display element used in the projection display device does not emit light by itself, it is necessary to provide a separate light source.
Compared with cathode ray tubes used for projection type cathode ray tube display devices, they have excellent features such as wide color reproduction range, small size and light weight, easy to carry, and no need for convergence adjustment. ,
Future development is expected. The projection type color image display system using the liquid crystal display device as described above includes a three-plate system using three liquid crystal display devices according to three primary colors and a single plate system using only one liquid crystal display device. The former three-plate type projection color image display device has an optical system that divides white light into color lights of three primary colors of red, green, and blue, and a liquid crystal display element that controls the color lights to form an image. The image of each color is optically overlapped to perform full-color display.
With this three-plate type structure, the light emitted from the white light source can be effectively used, but the optical system is complicated and the number of parts is large, and in terms of cost and downsizing, it is more common than the single plate type described later. Is disadvantageous to

The latter single-plate type projection color image display apparatus projects a liquid crystal display element having three primary color filters formed in a mosaic or stripe pattern by a projection optical system. 59-23
No. 0383. The single-plate type uses only one liquid crystal display element, and the optical system can be configured with a simple optical system as compared with the three-plate type, and is suitable for a low-cost and small projection type system. However, since a color filter is used, only about 1/3 of the incident light can be used, and other light is absorbed or reflected by the color filter.
In other words, the brightness of the screen in the single plate type using color filters is about 1/3 of that in the three plate type using the same light source.
Will fall to.

Brightening the light source is one solution to the decrease in brightness, but when it is used for consumer use, it is not preferable to use a light source with large power consumption. In addition, when an absorption type color filter is used, the energy of the light absorbed by the color filter changes to heat. Therefore, brightening the light source unnecessarily causes not only the temperature rise of the liquid crystal display element but also the fading of the color filter. Be accelerated. Therefore, how to effectively use the given luminous flux is an important issue for improving the utility value of the projection type color image display device.

Therefore, in order to solve the drawbacks of such a single plate type projection color image display device, a color image display device has been proposed in which a plurality of dichroic mirrors are arranged in a fan shape to improve the light utilization rate. (JP-A-4-60538
issue).

FIG. 7 is a schematic diagram of a single-panel projection type color image display device disclosed in Japanese Patent Laid-Open No. 4-60538. Light from the white light source 1 having the spherical mirror 2 is converted into substantially parallel light by the condenser lens 3, and the white light flux is received by the three types of dichroic mirrors 13R, 13G, and 13B. The dichroic mirrors 13R, 13G, 13B are
They are arranged in a fan shape at different angles in this order on the optical axis. In addition, the dichroic mirrors 13R, 13G,
13B has a property of selectively reflecting light in each wavelength band of red, green, and blue, and transmitting the other, and is formed by a well-known multilayer thin film coating technique. Below R,
G and B respectively represent red, green and blue colors.

Dichroic mirrors 13R, 13G, 1
The R, G, and B light fluxes created by 3B are incident on the microlens array 6 that is arranged by being attached to the light source side of the liquid crystal display element 7. The liquid crystal display element 7 has a liquid crystal portion driven by display electrodes to which corresponding color signals are independently applied, and the liquid crystal portion is a pixel opening. One of the microlens arrays 6 is configured to distribute and irradiate the light flux to the pixel opening for each color, and to converge the light flux on each pixel opening. The cycle of the microlens of the microlens array 6 corresponds to the cycle of R, G, and B pixels of the liquid crystal display element 7.
The light flux that has passed through the liquid crystal display element 7 is projected onto the projection screen 10 by the field lens 8 and the projection lens 9.

As another method, a method has been proposed in which a hologram element that simultaneously performs color separation and convergence to a pixel opening is applied to a direct-view liquid crystal display element to improve the utilization efficiency of illumination light ( JP-A-6-222361). FIG. 8 is a block diagram of an embodiment in JP-A-6-222361. In this configuration, the hologram element 14 is provided on the light incident side of the liquid crystal display element 15. The hologram element 14 is a type of hologram that causes diffraction in all wavelength regions of incident light. Hologram element 14
When white light is incident on, the light is diffracted at different angles depending on the size of the wavelength of the light component contained in the white light. Further, the hologram element 14 has a function of converging light in a cycle of R, G, and B pixels of the liquid crystal display element 15, and by this function, a predetermined color is provided in the pixel opening portion of each color of the liquid crystal display element 15. Converge the light of.

In another embodiment of the above-mentioned Japanese Patent Laid-Open No. 6-222361, an incident light is condensed by a microlens array having a period of 3 pixels of R, G and B, and a hologram element installed behind it. Light is diffracted at different angles depending on the size of the wavelength, and the light is distributed to the R, G, and B pixel apertures of the liquid crystal display element. Incidentally, JP-A-6-222361
Color filter 16 in the liquid crystal display element 15 in FIG.
Is provided. The above is what has been described in JP-A-6-2819.
No. 32 is also disclosed.

Further, in another embodiment of Japanese Patent Laid-Open No. 6-222361, a hologram element which diffracts at different angles depending on the size of the wavelength and a hologram element which functions to converge light are disclosed. There is.

[0011]

By the way, in the above-mentioned Japanese Patent Laid-Open No. 4-60538, the single plate type projection color image display device does not use the absorption type color filter, but the light utilization efficiency is improved. There was such a problem.

In FIG. 7, dichroic mirrors 13R, 13G and 13B which sequentially reflect only predetermined wavelength band components.
Due to this, the white light flux is separated into light fluxes of each color, but for that reason, since the path of the light flux is bent so as to be greatly bent by 60 ° to 90 °, the space occupied by the optical system becomes large. In addition, the dichroic mirrors 13R, 13G, 13
Since B is disposed obliquely with respect to the optical path, dichroic mirrors 13R and 13R are provided as compared with the case where they are placed vertically in the optical path.
It is necessary to increase the surface area of G and 13B, which increases the cost of the optical component.

The dichroic mirrors 13R and 13R
The light fluxes of the respective colors divided by G and 13B are incident on the liquid crystal display element 7 at different angles. At this time, at the same time, the dichroic mirrors 13R, 13G, so that the light fluxes of the respective colors overlap on the liquid crystal display element 7 in substantially the same manner. It is necessary to set 13B. This is to prevent the white balance from being lost due to a change in the mixing ratio of R, G, and B light within the plane of the liquid crystal display element 7.

In the projection type color image display device of the single plate type disclosed in Japanese Patent Laid-Open No. 4-60538, the emission angle of the light flux from the liquid crystal display element is different for each color, and the spread of the entire light is considerably large. ing. FIG. 9A shows the emission angle of light for each color.

By the way, in order to project all the luminous fluxes emitted from the liquid crystal display element on the screen, it is necessary to use a large-diameter (small F value) projection lens shown by a large-diameter circle in FIG. 9B. However, the smaller the F value, the more difficult it is to manufacture the projection lens, which causes a cost increase. When an F-number larger than the F-number required for cost reduction, that is, a small-diameter projection lens indicated by a small-diameter circle in FIG. 9B is used, vignetting of the R and B lights at the pupil position of the projection lens (Fig. 9 (b), the light flux reaching the screen of these two color lights decreases. Of the light sources often used in liquid crystal projectors, for example, metal halide lamps, halogen lamps, etc. have non-uniform spectral distribution.Metal halide lamps do not have a bright line in the red region, so red is weak, and halogen lamps have a bright line in the blue region. Since there is no spectrum, blue has a weak spectrum distribution.
For this reason, when a small-diameter projection lens and the above-mentioned lamp are used, originally a small amount of colored light is further vignetted at the pupil position of the projection lens, and the white balance is largely shifted to the green side. In other words, in the projection type color image display device of the single plate type disclosed in JP-A-4-60538, when a light source having a non-uniform spectrum is used and a projection lens having an F value larger than that required for cost reduction is used, It has a drawback that the white balance is deteriorated due to vignetting at the pupil position of the lens.

Next, conventional problems in the above-mentioned JP-A-6-222361 and JP-A-6-281932 will be described. These Japanese Patent Laid-Open No. 6-222361 and the like also improve the light utilization efficiency, but have the following problems.

(1) The hologram element 14 needs a periodic structure because it has a function of converging light as described above. Therefore, it is necessary to accurately align the pixels of the liquid crystal display element 15. However, as compared with the microlens array that converges white light, the hologram element 14 has an additional function of color separation, and this function hinders the positioning work, and accurate positioning is difficult. Is. In particular, it is very difficult to align the microlens array, the hologram element, and the liquid crystal display element because each has a periodic structure.

(2) The hologram element has an advantage that once a master is produced, it can be duplicated and mass-produced thereafter. However, in order to reproduce a condensed state equivalent to that of a microlens, the hologram element 14 must have a function of condensing light corresponding to the pixels of the liquid crystal display element, and therefore it is necessary to perform exposure in multiple times. As a result, the process becomes complicated and it is difficult to make a large master hologram element.

(3) When the light is converged by the microlens array and the color is separated by the hologram element behind the microlens array, the incident angle distribution of the light is generated at the time of entering the hologram element, and the diffraction angle Is slightly different. Therefore, the condensed spot in the pixel opening becomes large, and in order to correct it, it is necessary to give the interference fringes of the hologram element periodicity according to the shape of the microlens array. Disadvantages of giving periodicity to such a hologram element are the above (1)
As described in.

The present invention has been made to solve the above problems of the prior art, and provides a projection type color image display device which can be reduced in weight and size and can be manufactured at low cost. With the goal.

[0021]

A projection type color image display device of the present invention has a wavelength selectivity, which divides a light source and a light beam from the light source into light beams of a plurality of colors and diffracts them in different directions. An optical element, a microlens array for converging the light fluxes of the plurality of colors from the hologram element, and a liquid crystal display element on which the light fluxes of the plurality of colors converged by the microlens array are incident on corresponding pixels. Optical means for receiving the light fluxes of the plurality of colors modulated by the liquid crystal display element and projecting an image displayed on the liquid crystal display element.
Out of the three primary color lights incident on the liquid crystal display element,
The liquid crystal display device emits color light whose emission spectrum of the light source is the weakest.
The optical element so that the light is incident at an angle close to the normal to the display surface of
The diffraction wavelength range and the diffraction angle are selected to achieve the above object.

As the optical element, two or more hologram elements having different wavelength ranges and diffracted angles of diffracted light beams may be laminated and used, and the light beams of two or more wavelength ranges may have different wavelengths. It may be configured by a multiple hologram element having a bending angle.

[0023]

[0024]

According to the constitutions of claims 1 to 3, it is not necessary to reflect the white light flux from the light source and bend the optical path as in the conventional case.
Since the optical element that is the color dividing means is arranged substantially perpendicular to the optical path, it becomes possible to superimpose the optical element on the microlens array and the liquid crystal display element. Therefore, the optical path length of the device can be shortened as compared with the conventional device, whereby the projection type color image display device can be reduced in weight and size and the cost can be reduced. In addition, color light with a weak emission spectrum is displayed on the liquid crystal display.
Incidents and exits at an angle close to the normal to the display surface of the device
Since it is a projection lens with a small diameter (high F value) for cost reduction
Even if you use the lens, there is no vignetting at the pupil position of the projection lens.
Therefore, good white balance can be maintained.

In the second aspect, the optical element is formed by stacking hologram elements having wavelength selectivity. Since this hologram element can be mass-produced at low cost by making a replica after making a master, the cost can be reduced as compared with the case where a dichroic mirror is used as in the conventional case.
Further, by disposing the hologram element in front of the microlens, the hologram element itself may not have a periodic structure. Therefore, it does not require as precise alignment as the microlens array. Further, therefore, the hologram element can be easily manufactured.

Further, in the third aspect, since the optical element of the color dividing means is composed of one multiplex hologram element, the number of parts is reduced and the effect of cost reduction is further enhanced.

[0027]

As the constituent elements of the hologram element,
As shown in FIG. 5, a hologram element produced by recording interference fringes of two light fluxes formed on a hologram recording substrate can be used. Here, the angle setting of the two light beams is described in “Laser and Image” by Shizuo Tatsuoka (Kyoritsu Shuppan) p. 77-81
As described above, it may be specified so that the light in the wavelength range to be used causes interference fringes that satisfy the Bragg diffraction condition.

[0029]

EXAMPLES Examples of the present invention will be described below.

(Embodiment 1) FIG. 1 is a schematic view showing an entire projection type color liquid crystal display device according to the present invention. The color image display device of this embodiment includes a white light source 1 having a spherical mirror 2, a condenser lens 3, hologram elements 4 and 5 that exert a diffraction effect only on G and B, and a microlens array 6. The liquid crystal display element 7 is provided, a projection optical system including a field lens 8 and a projection lens 9, and a projection screen 10.

As the white light source 1, a metal halide lamp having a power consumption of 150 W and an arc length of 5 mm is used in this embodiment, but a halogen lamp, a xenon lamp or the like may be used. A spherical mirror 2 is arranged on the back surface of the white light source 1, and a condenser lens 3 having a diameter of 80 mmφ and a focal length fc of 60 mm is arranged on the front surface.

The center of the spherical mirror 2 is arranged so as to coincide with the center of the light emitting portion of the white light source 1, and the center of the light emitting portion of the white light source 1 is arranged so as to coincide with the focal point of the condenser lens 3. The light flux emitted from the condenser lens 3 is substantially parallel light. The means for obtaining the parallel light flux from the white light source 1 is not limited to the method using the condenser lens described above, but a method using a rotating parabolic mirror, a method using a spheroidal mirror and an integrator in combination is appropriately selected.

In order to reduce the temperature rise of the liquid crystal display element 7, a UV-IR cut filter (omitted in FIG. 1) for cutting ultraviolet rays (UV) and infrared rays (IR) which are unnecessary for color image display. 1) is inserted between the condenser lens 3 and the liquid crystal display element 7 in FIG.

FIG. 2 is a sectional view schematically showing the vicinity of the liquid crystal display element 7 used in this embodiment. However, in FIG. 2, a polarizing plate, an alignment film and the like, which are components of the liquid crystal display element 7, are omitted for simplification.

The hologram element 4, the hologram element 5, and the microlens array 6 are stacked and attached to the liquid crystal display element 7 on the light incident side, that is, the surface of the condenser lens 3 side in the order of increasing distance from the liquid crystal display element 7. There is. The white light flux that has passed through the condenser lens 3 and becomes substantially parallel light enters the hologram elements 4 and 5 substantially vertically. The hologram element 4 is configured to exert a diffraction effect only on the G light flux, and the hologram element 5 is configured to exert a diffraction effect only on the B light flux. The R light flux that is not diffracted passes through the hologram elements 4 and 5 as it is. G and B in the hologram elements 4 and 5
By appropriately selecting the diffraction angle of, the G and B luminous fluxes of the incident white luminous flux are emitted at different angles by θ so as to be symmetric with respect to the R luminous flux within the plane of the drawing.

This relative angle θ is given by the following equation (1), where P is the pixel arrangement pitch of the liquid crystal display element 7 described later and f is the focal length of the microlens array 6.

Θ = tan ⁻¹ (P / fμ) (1) In this embodiment, as a hologram recording photosensitive material, for example, Omnidex 352 manufactured by DuPont Co., Ltd. is used as shown in FIG. The coated transparent substrate is irradiated with two parallel light beams by an argon laser (wavelength 514.5 nm) with the angle between them being adjusted, and the interference fringes generated at this time are recorded, whereby a hologram for G is produced. Element 4 and hologram element 5 for B were prepared. As the hologram recording light source, in addition to the above, a He-Ne laser, K
An r laser or the like can be used.

FIG. 4 shows the hologram element 4 in FIG.
Only the number 5 is extracted to show the light traveling path.
In the present invention, since the light corresponding to the pixels of the liquid crystal display element 7 is converged by the microlens array 6 installed behind the hologram elements 4 and 5, the diffraction conditions of the hologram elements 4 and 5 are constant in the plane. The periodicity is unnecessary, and the recording of interference fringes is completed once. Also,
The hologram elements 4 and 5 of this embodiment are different from those used in the conventional example in that they are holograms having wavelength selectivity.

Due to the action of the hologram elements 4 and 5, the respective light fluxes of R, G and B enter the microlens array 6 existing on the exit side of the hologram elements 4 and 5 at different angles. In FIG. 1, the R light flux enters the microlens array 6 vertically.

The microlens array 6 is a liquid crystal display element 7
One microlens is arranged so as to correspond to the three pixels corresponding to R, G, and B, and the focal length fμ thereof is 720 μm (in the glass substrate, the counter substrate thickness of 1.
1 mm) and attached to the liquid crystal display element 7 with an optical adhesive.

The liquid crystal display element 7 has rectangular pixels 12 arranged in a matrix in a delta arrangement as shown in FIG.
However, a twisted nematic mode (TN) active matrix type liquid crystal display element which is driven for dynamic display through a semiconductor thin film transistor that switches the pixel 12 is used. The pixel pitch is 100 μm in both length and width, and the size of the pixel opening is 50 μm in length × 70 in width.
μm, and the number of pixels was 480 (vertical) × 640 (horizontal).

Therefore, since the focal length fμ of the microlens array 6 is 720 μm and the pixel pitch P of the liquid crystal display element 7 is 100 μm, in the present embodiment, the hologram element is diffracted with respect to the R light based on the above equation (1). The angle θ is
θ = tan ⁻¹ (100/720) ≈8 °. Therefore, the light flux of R is vertically incident on the liquid crystal display element 7, and G, B
The two light fluxes of 1 are incident at an angle of ± θ.
As a result, the condensed spots of each color by the microlens array 6 are incident on the corresponding pixels of the liquid crystal display element 7.

The liquid crystal display element 7 modulates the incident light by the drive signal based on the input image signal. The light that has undergone this modulation and has passed through the liquid crystal display element 7 is efficiently guided to the projection lens 9 by the field lens 8, and the projection lens 9 magnifies and projects the color image made by the liquid crystal display element 7 on the projection screen 10. .

When the microlens array 6 is attached to the incident side surface of the liquid crystal display element 7, it is necessary to precisely adjust the positions of the pixels and the microlenses as in the conventional case.
Since the hologram element of the present invention does not have a periodic structure, accurate position adjustment is not required. This also applies to Example 2 described later.

By arranging the hologram elements 4 and 5 at a very short distance to the microlens array 6 and the liquid crystal display element 7, the illuminance distribution of the R, G, and B light fluxes on the liquid crystal display element 7 is obtained. The deviation can be almost ignored. In this embodiment, the hologram elements 4 and 5 are attached to the microlens array 6 to minimize the deviation of the illuminance distribution and enhance the white balance of the projected image. This also applies to the second embodiment.

In this embodiment, since the metal halide lamp is used as the light source 1, the R component is the weakest in the emission spectrum, but since the light flux of R is arranged at the center, the diameter of the projection lens 9 is reduced for cost reduction. Even if vignetting does not occur, white balance is unlikely to deteriorate. This is because, for example, when a halogen lamp with a small amount of B light is used as the light source 1, the hologram elements 4 and 5 are R and G other than B.
It suffices to use one that diffracts, in which case R,
The arrangement of each microlens and pixel of the microlens array 6 is appropriately changed so that each light flux of G and B is condensed on the pixel of the corresponding color of the liquid crystal display element 7. When the emission spectrum of the light source is uniform, the aperture of the projection lens 9 is large, and vignetting can be sufficiently ignored, the hologram elements 4, 5
The color diffracted by is not limited to the example of FIG. 2 and can be freely selected.

As a method of manufacturing the above-mentioned microlens array 6, an ion exchange method {Appl. Opt. Vo
l. 21, p. 1052 (1984), or Elect
ron. Lett. Vol. 17, p. 452 (198
1)} can be used. Furthermore, the swelling method (Suzuki et al., “New Manufacturing Method for Plastic Microlenses, 24th Micro Optical Research Group”), thermal sag method {Zoran D. et al. Popov
ic et al. "Technique for m
onolitic fabrication of m
icrolenz arrays ”, Appl. Op.
t. Vol. 27, p. 1281 (1988)}, vapor deposition method (JP-A-55-135808), thermal transfer method (JP-A-61-64158), machining method, or JP-A-3-
The method shown in No. 248125 can be used.

In the present invention, since the liquid crystal display element 7 is attached to one surface of the microlens array 6 and the hologram elements 4 and 5 are attached to the other surface, the optical surfaces of the microlens array 6 are flat on both sides. It is more preferable in terms of mechanical strength.

Therefore, in this embodiment, a microlens array manufactured by an ion exchange method in which a gradient index microlens is formed in a flat glass is used. However, the manufacturing method of the microlens array used in the present invention is not limited to the ion exchange method. For example, even in the case of a manufacturing method in which a microlens having a physical shape is formed on a flat substrate such as a thermal sag method, a step of providing a leveling layer, a cover glass, or the like on the surface on which the lens-shaped irregularities are formed and flattening is added. By doing so, it is possible to manufacture without impairing the light condensing function and the mechanical strength after bonding. This also applies to the second embodiment.

(Embodiment 2) FIG. 6 is a view showing the vicinity of a multiplex hologram element used as a hologram element for a projection type color image display device of this embodiment.

The basic structure of the projection type color image display device of the second embodiment is almost the same as that of the first embodiment. Instead of using the hologram elements 4 and 5 in superposition, two interference fringes are formed on one hologram. Multiplex hologram element 11 recorded in an overlapping manner
Is used.

The method of writing the interference fringes on the multiplex hologram element 11 is basically the same as the hologram element used in the first embodiment, but it is necessary to write a plurality of interference fringes on one hologram. . Specifically, the following can be done. For example, G and B as in the first embodiment
When writing two interference fringes corresponding to the above, first, the interference fringe corresponding to one light (either G or B may be written), and then the interference fringe of the other light is written. In this case, the exposure amount for each interference fringe needs to be half that in the case of recording only once.

Based on the above manufacturing method, the same photosensitive material and laser as in Example 1 were used to prepare a multiple hologram 11 in which two interference fringes corresponding to G and B were written. As a result, the hologram element of Example 1 was produced. The same effect as when 4 and 5 were laminated was obtained.

In the first and second embodiments described above, the hologram element is manufactured by the method of writing the interference fringes of light as a difference in the refractive index using the photosensitive material. A method of using a blazed grating or a grating using a cured resin or transparent plastic can be adopted.

Further, in the first and second embodiments described above, two hologram elements or one multiplex hologram element having selectivity for one wavelength are used, but the present invention is not limited to this. For example, any other material having wavelength selectivity and capable of reproducing white light can be used. In this case, one hologram element can adjust the emission angles of two or more light beams.

Further, in the present invention, in order to improve color purity, three hologram elements corresponding to three colors of R, G and B, or one multiple hologram element may be used.

Further, according to the present invention, there is provided a hologram element which does not allow unnecessary light other than R, G and B, which is a factor of color purity deterioration, to enter a pixel, for example, a hologram element having a characteristic of reflecting light by diffraction. The added configuration may be adopted.

Further, the hologram elements 4, 5 and 11 used in the above-described embodiment can be mass-produced with the optical element having the same diffraction effect by the known duplication technique after the recording and production by the above-described method once. Can be made into Therefore, the cost can be reduced as compared with the case where the conventional dichroic mirror is used as the color separation means. Further, the optical path length from the color separation to the liquid crystal display element can be minimized, and the size of the entire projection type color image display device can be reduced.

Further, in Examples 1 and 2, the field lens 8 side of the liquid crystal display element 7 is diffracted so that the principal rays of the R, G, and B light fluxes are parallel to each other, and there is wavelength selectivity. The hologram elements may be arranged so as to overlap each other.
As a result, it is possible to prevent the condensing position of the projection lens 9 at the entrance pupil from varying depending on the color, and to make it overlap in one place. As a result, the diameter of the projection lens can be reduced, and the cost can be reduced. As the hologram element used for this purpose, the same hologram elements as the hologram elements 4, 5 and 11 of the present invention can be used. FIG. 10A is a diagram showing the configuration and the progress of light in the vicinity of the liquid crystal display element 7 in that case, and FIG. 10B is also a schematic configuration diagram of the entire projection type image display device. When a hologram element that diffracts G and B light is selected as in the first embodiment, the hologram elements 16 and 17 provided on the field lens 8 side of the liquid crystal display element 7 also use those that diffract G and B light. Then, the traveling direction of the light flux is made the same as that of the R light.

(Embodiment 3) Another embodiment of the present invention is shown in FIG.
It will be described based on 1.

The major difference between the third embodiment and the first and second embodiments is that a substantially parallel white light flux made up of the white light source 1, the reflecting mirror 2, the condenser lens 3, etc.
The optical axis composed of the field lens 8 and the projection lens 9 is a point at which the light is incident obliquely. Hologram elements 18, 19,
Reference numeral 20 diffracts R, G, and B lights so that R is incident in the direction normal to the display surface of the liquid crystal display element, and G and B are incident at different angles by θ with respect to the R luminous flux. Has wavelength selectivity. Hologram elements 18, 19,
The light beam diffracted by 20 is in the same state as that in the first embodiment after that, and is projected on the projection screen 10 following the same path, so that the description thereafter is omitted.
Note that the hologram elements 18, 19 and 20 may be replaced with a single multiplex hologram element in accordance with the modification of the second embodiment with respect to the first embodiment.

[0062]

As described above, according to claims 1 to 3 of the present invention.
In the projection type color image display device described in (1), the optical path length from the light source to the liquid crystal display element can be shortened, and thereby the weight and size can be reduced, and a low cost device can be provided.
Also, keep the white balance of the projected image.
In addition, the cost of the projection lens can be reduced.
It

In the structure according to the second aspect, the cost of the optical component can be reduced by using the hologram element which can be mass-produced. In the structure described in claim 3, since only one hologram element is required, the number of parts can be reduced and further cost reduction can be achieved.

[0064]

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a projection type color image display device according to a first embodiment of the invention.

FIG. 2 is a detailed view (cross-sectional view) of a liquid crystal display element included in the projection type color image display device shown in FIG.

FIG. 3 is a front view schematically showing a microlens array and a pixel array of a liquid crystal display element provided in the projection type color image display device shown in FIG.

FIG. 4 is a diagram showing the vicinity of a hologram element used in Example 1 of the present invention.

5 is an explanatory diagram of a method of manufacturing the hologram element of FIG.

FIG. 6 is a diagram showing the vicinity of a multiplex hologram element used in Example 2 of the present invention.

FIG. 7 is a diagram showing a conventional projection type color image display device.

FIG. 8 is a diagram showing a conventional image display device.

FIG. 9 (a) shows how a light beam travels after passing through a liquid crystal display element in a conventional example (Japanese Patent Laid-Open No. 4-60536),
FIG. 6B is a diagram showing vignetting at the projection lens pupil position.

10A is a detailed view (cross-sectional view) of a main part of a liquid crystal display element according to another embodiment of the present invention, and FIG. 10B is a schematic view of a projection type color image display device using the liquid crystal display element. FIG.

11A is a diagram showing the vicinity of a hologram element in Example 3 of the present invention, and FIG. 11B is a schematic diagram showing a projection type color image display device using the hologram element.

[Explanation of symbols]

1 white light source 2 spherical mirror 3 condenser lens 4, 5 hologram element 6 Micro lens array 7 Liquid crystal display element 8 field lens 9 Projection lens 10 Projection screen 11 Multiple hologram element 12 pixels 13R, 13G, 13B Dichroic mirror 14 Hologram element without wavelength selectivity 15 Liquid crystal display device

Continuation of front page (51) Int.Cl. ⁷ Identification code FI G02B 5/32 G02B 5/32 G02F 1/13 505 G02F 1/13 505 1/13357 H04N 9/31 C H04N 9/31 G02F 1/1335 530 (56) References JP-A-7-98454 (JP, A) JP-A-6-222361 (JP, A) JP-A-4-60538 (JP, A) JP-A-5-34817 (JP, A) Kaihei 8-114780 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03B 21 / 00-21 / 30

Claims (3)

(57) [Claims] 1. A light source, an optical element having wavelength selectivity for dividing a light beam from the light source into light beams of a plurality of colors and diffracting the light beams in different directions, and a light beam of the plurality of colors from the hologram element. Array for converging light, a liquid crystal display element on which the light fluxes of the plurality of colors converged by the microlens array enter the corresponding pixels, and light fluxes of the plurality of colors modulated by the liquid crystal display element receiving, comprising optical means for projecting an image displayed on the liquid crystal display element, a, of the three primary color light incident on the liquid crystal display device, the light source
The color light with the weakest emission spectrum of is displayed on the liquid crystal display device.
The optical element is rotated so that it is incident at an angle close to the surface normal.
Projection-type color image display device with selected folding wavelength range and diffraction angle . 2. The projection type color image display device according to claim 1, wherein the optical element is formed by laminating two or more hologram elements having different wavelength regions and different diffraction angles of a diffracted light beam. 3. The projection type color image display device according to claim 1, wherein the optical element comprises a multiple hologram element having different diffraction angles for wavelength regions of two or more light beams.