JPH1097012A - Color resultant optical device and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact inexpensive color resultant optical device capable of efficiently making three kinds of color light beams resultant by adopting such a constitution that the third color light beam is made diagonal incident on a mirror selective in an incident angle and reflected by a second dichroic mirror, to vertically pass through the mirror selective in the incident angle. SOLUTION: The color resultant optical device is constituted of a first dichroic mirror 41, the second dichroic mirror 42 and the mirror selective in the incident angle 43. This mirror 43 is provided with an optical multilayer film 54 for making a vertical incident light beam pass through and reflecting a diagonal incident light beam on one surface of a glass substrate. In this device, the first color light beam 62 and the second color light beam 64 are made resultant by the first dichroic mirror 41, to be a two-color resultant light beam 65 and outgoing. The third color light beam 67 is made diagonal incident on the mirror 43, to be reflected and the reflected light beam 68 and the two-color resultant light beam 65 are made resultant by the second dichroic mirror 42, to be a three-color light beam 69 and outgoing. The three-color resultant light beam 69 vertically passes through the mirror 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Color synthesizing optical device for synthesizing two lights, projection display device using the color synthesizing optical system, color separation optical system for separating one light into three primary color lights, and imaging device using the color separation optical device It is about.

[0002]

2. Description of the Related Art In order to obtain a large-screen image, a method of forming an optical image corresponding to an image signal on a light valve, irradiating the optical image with light, and enlarging and projecting the image on a screen by a projection lens is better than the conventional method. Are known. Recently, a projection type display device using a liquid crystal panel as a light valve has attracted attention, and a projection type display device using a phenomenon in which the optical rotation of a twisted nematic (TN) liquid crystal is changed by an electric field has already been commercialized.

Incidentally, the TN liquid crystal panel requires polarizing plates on the incident side and the emitting side, and about half of the incident light is discarded by the incident side polarizing plate, so that the light use efficiency is low. I have A polymer dispersed liquid crystal panel has been proposed as a liquid crystal panel that can solve this problem (for example, Japanese Patent Application Laid-Open No. 1-261620).

FIGS. 12A and 12B show the basic structure and operation model of a polymer dispersed liquid crystal panel. Glass substrates 1, 2
The polymer-dispersed liquid crystal 3 is interposed therebetween. Transparent electrodes 4 and 5 are provided on the inner surfaces of the two glass substrates 1 and 2, respectively. The polymer-dispersed liquid crystal 3 has a structure in which liquid crystals 7 in the form of water droplets are dispersed in a polymer resin material 8. The ordinary light refractive index of the liquid crystal 7 and the refractive index of the polymer resin material 8 are substantially equal. When no voltage is applied to the liquid crystal layer 3, the liquid crystal molecules 9 are oriented in random directions as shown in FIG. Since a difference in the refractive index occurs at the interface between the liquid crystal 7 and the polymer resin material 8 with respect to the light beam 10 vertically incident on the liquid crystal layer 3, the light beam 1
0 repeats refraction at a boundary surface having a refractive index difference, and emits as scattered light. When a sufficient voltage is applied to the liquid crystal layer 3, the liquid crystal molecules 9 are oriented in a direction perpendicular to the glass substrates 1 and 2, and the refractive indices of the liquid crystal 7 and the polymer material 8 with respect to the incident light 10 as shown in FIG. Are equal, the incident light 1
0 is emitted straight without being scattered.

FIG. 13 shows a configuration example of a projection display device using a polymer dispersed liquid crystal panel. Light emitted from the lamp 11 is condensed by the concave mirror 12 and enters the liquid crystal panel 13. When a sufficient voltage is applied to the entire display area of the liquid crystal panel 13, all of the light coming out of the concave mirror 12 and entering the liquid crystal panel 13 enters the projection lens 14. The liquid crystal panel 13 is a polymer dispersed liquid crystal panel, and a polymer dispersed liquid crystal 17 is sandwiched between glass substrates 15 and 16. A matrix-like pixel electrode is provided on the surface of one glass substrate 16 on the side of the liquid crystal layer 17, and a common electrode is provided on the other glass substrate 15. An optical image can be formed as a change in the scattering state. Since all the light emitted from the pixels to which a sufficient voltage is applied enters the projection lens 14 and reaches the screen 18, the screen 18
Bright pixels are displayed at the corresponding positions above. A scattered light is emitted from a pixel to which no voltage is applied, and only a part of the light is incident on the projection lens 14, so that a dark pixel is displayed at a corresponding position on the screen 18. In this way, the optical image formed as a change in the scattering state on the liquid crystal panel 13 is enlarged and projected on the screen 18 by the projection lens 14.

In order to improve the light output and the resolution, it is preferable to use three liquid crystal panels for red, green and blue. In order to increase energy efficiency and reduce costs, the number of lamps is preferably one, and the number of projection lenses is preferably one in order to prevent convergence deviation even when the positional relationship between the projection lens and the screen is changed. In this case, a color separation optical device for separating light emitted from the lamp into three primary colors of red, green, and blue, and a color combining optics for combining light emitted from the three light valves into one light. Equipment is required. The color separation optics and the color composition optics are
It is preferable to use a dichroic mirror.

FIG. 14 shows an example of the configuration of a projection display device using three polymer-dispersed liquid crystal panels. The light source is constituted by the lamp 21, the concave mirror 22, the filter 23, the cold mirror 24, the first relay lens 25, and the second relay lens 26. The lamp 21 emits light including the three primary colors of red, green and blue, and the light is emitted by the concave mirror 22 to the first relay lens 25.
To focus the light. On the way, a filter 23 that reflects infrared light and ultraviolet light and transmits visible light, and a cold mirror 24 that reflects visible light and transmits infrared light
Is arranged.

The light emitted from the first relay lens 25 is
The light is converted into a light having a small divergence angle by the second relay lens 26, and is incident on a color separation optical device composed of two dichroic mirrors 27 and 28 and a plane mirror 29, where red,
It is decomposed into three primary colors of green and blue. The primary color lights pass through the field lenses 30, 31, and 32 and enter the liquid crystal panels 33, 34, and 35, respectively. Each liquid crystal panel 3
3, 34, 35 form an optical image as a change in the light scattering state, and the light emitted from each of the liquid crystal panels 33, 34, 35 is a color combining optic composed of two dichroic mirrors 36, 37 and a plane mirror 38. The light enters the device, is combined into one light, and enters the projection lens 39. Thus, the optical images formed on the three liquid crystal panels are enlarged and projected on the screen by the projection lens 39.

In addition to the color synthesizing optical system shown in FIG. 13, there is known a color synthesizing optical device in which four right-angle prisms are bonded so that the bonding surface has an X shape, and a dichroic multilayer film is provided on the bonding surface. Have been. In a video camera using three image pickup devices, a color separation prism in which three triangular prisms are combined and a dichroic multilayer film is vapor-deposited on the prism to separate light emitted from the image pickup lens into three primary color lights. (For example, Japanese Patent Publication No. 38
No. 23724, JP-A-50-159618). This color separation prism can also be used as a color combining optical device.

[0010]

In a dichroic mirror, the spectral transmittance characteristic differs between S-polarized light and P-polarized light, and the cut-off wavelength (wavelength at which the transmittance becomes 50%) of the spectral transmittance characteristic depends on the incident angle. It has the property of changing. When using a light valve that modulates the polarization state,
Since linearly polarized light is emitted from the light valve, only one of S-polarized light and P-polarized light can be made incident on the color synthesizing dichroic mirror, and there is no problem of efficiency reduction due to PS difference. However, when a light valve using a polymer dispersed liquid crystal is used, natural light is emitted from the light valve,
Since both the S-polarized light and the P-polarized light are incident on the color combining dichroic mirror, the efficiency of the color combining optical device decreases when the PS difference in the spectral transmittance characteristics is large. Projection-type display devices using polymer-dispersed liquid crystals are said to have higher overall efficiency than projection-type display devices using polarizing plates, but the overall efficiency of the color separation optical system and the color synthesis optical system is low. However, there is a problem that the energy efficiency of the entire device is reduced.

The dichroic mirror includes a flat type and a prism type. The prism type dichroic mirror has higher incidence angle dependence and is more expensive than the flat plate type dichroic mirror. Therefore, it is desirable to use a flat dichroic mirror for the color combining optical device. However, the flat dichroic mirror has a problem in that the flatness of the reflecting surface and the astigmatism affect the resolution. To improve the flatness of the reflection surface, it is preferable to increase the thickness of the glass substrate. However, as the thickness of the glass substrate increases, the astigmatic difference increases and the resolution decreases.

To cope with this problem, a configuration has been proposed in which the angle of incidence of incident light on a flat dichroic mirror is reduced (Japanese Patent Laid-Open No. 7-51419). But,
In this configuration, since the optical path from the light valve to the projection lens becomes long, the back focus of the projection lens needs to be lengthened, which causes a problem that the projection lens becomes expensive.

[0013]

SUMMARY OF THE INVENTION In order to solve this problem, a color synthesizing optical device according to the present invention comprises a first flat dichroic mirror for synthesizing a first color light and a second color light into a two-color synthesized light. A second dichroic mirror having a flat plate shape that combines the two-color combined light and the third color light into the three-color combined light, and a third color light that transmits the vertically incident three-color combined light and obliquely enters the three-color combined light. A flat-plate incident angle selective mirror for reflection,
The third color light is obliquely incident on the incident angle selective mirror,
Is reflected by the dichroic mirror and vertically transmitted through the incident angle selective mirror.

The color synthesizing optical device of the present invention can be used for a projection type display device using a light valve.

The color synthesizing optical device of the present invention can be used as a color separating optical device by reversing the traveling direction of light, and the color separating optical device can be used for an image pickup device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 shows a configuration of a color synthesizing optical apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 41 denotes a blue reflecting dichroic mirror, and 42 denotes a red reflecting dichroic mirror. , 43 are incident angle selective mirrors.

Two dichroic mirrors 41 and 42 are arranged obliquely with respect to a predetermined optical axis 44 so as to form a V-shape, and an incident angle selective mirror 43 is arranged perpendicularly to the optical axis 44. ing. Two dichroic mirrors 4
The angles between the normals 45 and 46 of the optical axes 1 and 42 and the optical axis 44 are all 30 °.

The blue reflection dichroic mirror 41 is formed by depositing an optical multilayer film 48 for reflecting blue light and transmitting red light and green light on the surface of the glass substrate 47 on the side of the red reflection dichroic mirror 42, and on the other surface. The antireflection film 49 is deposited. FIG. 2 shows the spectral transmittance characteristics of the blue reflection dichroic mirror 41 at an incident angle of 30 °. Cutoff wavelength of blue reflection dichroic mirror 41 (transmittance is 5
The wavelength at which 0% is reached is 500 nm.

The red reflecting dichroic mirror 42 is formed by depositing an optical multilayer film 51 for reflecting red light and transmitting green light and blue light on the surface of the glass substrate 50 on the side of the incident angle selective mirror 43, and the other surface. An anti-reflection film 52 is deposited on the substrate. FIG. 3 shows the spectral transmittance characteristics of the red reflection dichroic mirror 42 at an incident angle of 30 °. The cutoff wavelength of the red reflection dichroic mirror 42 is 600 nm.

The incident angle selective mirror 43 is provided on the glass substrate 5.
3 is an optical multilayer film 5 on the surface on the red reflection dichroic mirror side.
4, and an antireflection film 55 is deposited on the other surface. The optical multilayer film 54 is formed by alternately stacking titanium dioxide and silicon dioxide. FIG. 4 shows the spectral transmittance characteristics of the incident angle selective mirror 43. The dashed line indicates the case where the incident angle is 0 °, and the broken line indicates the case where the incident angle is 60 ° for S-polarized light.
The solid line is for P-polarized light at an incident angle of 60 °. In the case of normal incidence, red, green, and blue natural light are all transmitted efficiently, and when the incident angle is 60 °, red light is efficiently reflected.

Considering an optical multilayer film having a transmission band on the short wavelength side and a reflection band on the long wavelength side in a predetermined wavelength region in the case of normal incidence, the cutoff wavelength shifts to the short wavelength side as the incident angle increases. Therefore, in a certain wavelength region, the transmittance is high in the case of vertical incidence, and the reflectance is low in the case of oblique incidence. By utilizing this property, it is possible to realize an incident angle selective mirror that reflects desired color light in the case of oblique incidence and transmits red, green, and blue color light in the case of vertical incidence.

The green light 62 incident along the incident light axis 61 of the green light passes through the blue reflecting dichroic mirror 41,
The blue light 64 incident along the incident optical axis 63 of the blue light is reflected by the blue reflecting dichroic mirror 41, so that the green light 62 and the blue light 64 are combined to form a two-color combined light 65, which is a two-color combined light. 65 is a red reflection dichroic mirror 42
Incident on. The red light 67 incident along the incident optical axis 66 of the red light is reflected by the incident angle selective mirror 43, and the reflected light 68 enters the red reflection dichroic mirror 42. The two-color composite light 65 is applied to the red reflection dichroic mirror 42.
And the red light 68 is transmitted through the red reflecting dichroic mirror 4.
Since the light is reflected by 2, the two-color combined light 65 and the red light 68 are combined to form a three-color combined light 69. The three-color combined light 69 passes through the incident-angle selective mirror 43 and becomes the output light 70 and exits along the optical axis 44. In this way, the three color lights 62, 64, and 67 of red, green, and blue are combined into one light 70.

Reference angle of incidence of two dichroic mirrors 41 and 42 (angle between optical axis and dichroic mirror)
Are all 30 °, the initial reference incident angle of the red light on the incident angle selective mirror 43 is 60 °, and the reference incident angle of the three-color composite light on the incident angle selective mirror 43 is 0 °. The reference angle of incidence of the red light on the incident angle selective mirror 43 is twice the reference angle of incidence of the red reflection dichroic mirror 42.

The cutoff wavelength of the dichroic mirror differs between S-polarized light and P-polarized light. The difference between the two increases as the incident angle increases. Also, as the incident angle increases, the cutoff wavelength moves to the shorter wavelength side, but as the incident angle increases, the incident angle dependence of the cutoff wavelength increases.
Due to these two properties, when the reference incident angle is large,
Efficiency when combining three natural lights of red, green, and blue is reduced. Therefore, if the reference incident angle is changed from 45 ° shown in the conventional example to 30 °, both the PS difference of the cutoff wavelength and the incident angle dependency can be reduced, so that the three natural lights of red, green and blue can be used. It can be synthesized efficiently.

When the divergence angle of light incident on the color synthesizing optical device is small, two dichroic mirrors 41 and 4 are used.
When the reference incident angle of No. 2 is 30 °, the optical path length of the color combining optical device becomes the shortest. When the divergence angle of the incident light is large, the reference incident angles of the two dichroic mirrors 41 and 42 are preferably set to 25 ° or more and 35 ° or less. When the reference incident angle of the dichroic mirror 42 close to the incident angle selective mirror 43 is smaller than 25 °, the incident angle selective mirror 43
However, it is difficult to secure a wavelength band of color light reflected at oblique incidence and transmitted at vertical incidence. On the other hand, when the reference incident angle is larger than 35 °, as described later, the astigmatic difference between the two dichroic mirrors cannot be secured, or the flatness of the reflecting surface cannot be secured. Further, when the above range is not satisfied, it is necessary to prevent the three color lights from being shielded by the two dichroic mirrors 41 and 42, so that the back focus required for the projection lens becomes long and the projection lens becomes expensive. turn into.

The flat type dichroic mirror has a problem that the optimum image point differs between the meridional direction and the sagittal direction due to astigmatism. The astigmatic difference d of a glass substrate having a thickness t and a refractive index n is given by the following equation (Hiroshi Kubota, "Optics", Iwanami Shoten, 10th printing, September 25, 1979,
(Pages 130 to 131).

[0028]

(Equation 1)

Here, θ ₁ is the incident angle in air, and θ ₂ is the refraction angle in the glass substrate, and the following Snell's law holds.

[0030]

(Equation 2)

(Equation 1) shows that the astigmatism difference can be reduced by reducing the thickness of the glass substrate. However, when the glass substrate is made thinner, the glass substrate is easily warped, which causes a problem of a reduction in resolution and a convergence deviation. Therefore, the glass substrate should be thick enough not to warp,
At the same time, it is necessary to reduce the astigmatic difference.

It can be seen from Equation 1 that the smaller the incident angle, the smaller the astigmatic difference. For example, if n = 1.52, the incident angle 30 with respect to the astigmatic difference at an incident angle of 45 °
In the case of °, the ratio of the astigmatic difference is 41%. Therefore, if the astigmatism is the same, the glass substrate can be 2.4 times thicker, and the glass substrate is less likely to warp.

Since the light is incident perpendicularly on the incident angle selective mirror, no astigmatic difference occurs even if the glass substrate is made thick. Therefore, it is preferable that the incident angle selective mirror be made thicker to improve the flatness of the reflection surface.

The color synthesizing optical apparatus using a glass prism causes a great increase in cost because the work of processing and joining the glass prism becomes complicated. However, the color combining optical device of the present invention is overwhelmingly cheaper than a glass prism because the glass substrate is much cheaper than a color combining optical device using a glass prism.

In the configuration of the conventional projection display device shown in FIG. 14, when the reference angle of incidence of the color combining dichroic mirror is reduced, the optical path length of light passing through the color combining optical device becomes longer. In this case, it is necessary to lengthen the back focus required for the projection lens, which increases the cost of the projection lens. On the other hand, in the color synthesizing optical device of the present invention, by using the incident angle selective mirror 43, the optical path length of the light passing through the color synthesizing optical device does not become so long and becomes almost the same as the conventional one.

FIGS. 5 and 6 show a specific configuration of the color combining optical device. FIG. 5 is a side sectional view, and FIG. 6 is a plan view. Each of the two dichroic mirrors 41 and 42 and the incident angle selective mirror 43 is mounted on frames 71, 72 and 73, and the frames 71, 72 and 73 are mounted with screws so as to be sandwiched between two side plates 74 and 75. ing. In this way, the two dichroic mirrors 41 and 42 and the incident angle selective mirror 43 can be held and fixed precisely.

(Embodiment 2) FIG. 7 shows a configuration of a color separation optical apparatus according to Embodiment 2 of the present invention. In FIG. 7, reference numeral 82 denotes an incident angle selective mirror, and 85 denotes a red reflection dichroic. The mirror 90 is a blue reflecting dichroic mirror. The configuration of the color separation optical device shown in FIG. 7 is exactly the same as the configuration of the color synthesis optical device shown in FIG.

An incident angle selective mirror 82 along the optical axis 81
The input light 83 that has entered the vertical direction is transmitted vertically, and the transmitted light 8
4 enters a red reflecting dichroic mirror 85 and is decomposed into a red light 86 to be reflected and a combined light 87 of transmitted green light and blue light. Red reflective dichroic mirror 85
The red light 86 reflected by the incident light is obliquely incident on the incident angle selective mirror 82, is reflected, becomes red output light 88, and emerges along the red output optical axis 89. The combined light 87 of the green light and the blue light transmitted through the red reflection dichroic mirror 85 is
The light enters the blue reflection dichroic mirror 90, the blue light is reflected, becomes blue output light 91 and exits along the blue output optical axis 92, and the green light is transmitted and becomes the green output light 93 to produce the green output light 93. The light exits along the optical axis 94.

As in the color combining optical device shown in FIG.
Since the reference incident angles of the dichroic mirrors 85 and 90 are small, the PS difference of the cutoff wavelength and the incident angle dependence are small, and the astigmatic difference is also small. By the former function, the incident light can be efficiently separated into three primary color lights of red, green, and blue, and the lower function can reduce a decrease in resolution generated by the color separation optical device. The color separation optical device of the present invention has a very small reduction in resolution and is overwhelmingly inexpensive as compared with a color separation optical device using a prism type dichroic mirror. Further, by using the incident angle selective mirror 82, the optical path length of the light passing through the color separation optical device is not so long, which is almost the same as the conventional one.

(Embodiment 3) FIG. 8 shows the configuration of a projection display apparatus according to Embodiment 3 of the present invention. In FIG. 8, reference numeral 102 denotes a lamp, and 109 and 110 denote dichroic mirrors for color separation. , 119, 120, 12
1 is a liquid crystal panel, 122 is a color combining optical device, and 123 and 1
24 is a dichroic mirror for color synthesis, 125 is an incident angle selective mirror, and 126 is a projection lens. The color synthesizing optical device 122 has the same configuration as that shown in FIG.

Lamp 102, concave mirror 103, filter 1
04, cold mirror 105, first relay lens 10
6. The second relay lens 107 constitutes a light source.
The lamp 102 is a metal halide lamp,
It emits light containing the three primary colors of green and blue. The concave mirror 103 is an elliptical mirror, and is formed by depositing an optical multilayer film that reflects visible light and transmits infrared light on the inner surface of a glass substrate. The lamp 102 is arranged such that the center of the light emitter is located at the first focal point of the concave mirror 103. The filter 104 is formed by depositing an optical multilayer film that transmits visible light and reflects infrared light and ultraviolet light on one surface of a glass substrate, and deposits an antireflection film on the other surface. Cold mirror 105
Is formed by depositing an optical multilayer film that reflects visible light and transmits infrared light on a glass substrate, and is disposed at an angle of 45 ° with respect to the optical axis 108 of the concave mirror 103. The first relay lens 106 is disposed at the second focal point of the concave mirror 103.

The light emitted from the lamp 102 is condensed by the concave mirror 103 and reflected by the cold mirror 104, and thereafter, the first relay lens 106 and the second relay lens 107.
And then enter the color separation optical device.

The color separation optical device includes a blue transmission dichroic mirror 109, a green reflection dichroic mirror 110, a third relay lens 111, a fourth relay lens 112, three plane mirrors 113, 114, 115, field lenses 116, 117, 118. Light emitted from the light source enters the blue transmission dichroic mirror 109, blue light is transmitted, and red light and green light are reflected.
The light transmitted through the blue transmission dichroic mirror 109 is reflected by the plane mirror 113, passes through the field lens 116, and enters the blue liquid crystal panel 119. The light reflected by the blue transmission dichroic mirror 109 enters the green reflection dichroic mirror 110, where green light is reflected and red light is transmitted. The green light passes through the field lens 117 and is incident on the green liquid crystal panel 120, and the red light is the third relay lens 112, the plane mirror 114, the fourth relay lens 112, the plane mirror 115, and the field lens 118.
, And then enters the red liquid crystal panel 121.

The concave mirror 103 forms an image corresponding to the luminous body of the lamp 102 at the position of the first relay lens 106, and the second relay lens 107 forms the image corresponding to the first relay lens 106.
An image corresponding to the luminous body image above is displayed on a blue liquid crystal panel 119,
It is formed on the green liquid crystal panel 120 and the third relay lens 121. The third relay lens 111 converts a real image corresponding to an object on the second relay lens 107 into a fourth relay lens 11.
Formed at position 2. The fourth relay lens 112 converts the illuminant image on the third relay lens 111 into a red liquid crystal panel 121.
Form on top. Since the first relay lens 106 and the second relay lens 107 convert the light that is about to spread into convergent light, the light radiated from the lamp 102 can be efficiently converted into a blue liquid crystal panel 119, a green liquid crystal panel 120, and a third relay. It can be guided to the lens 111. Further, the optical path length from the light source to the liquid crystal panels 119, 120 and 121 is longer by the red optical path than the blue optical path and the green optical path, but the third relay lens 111 and the fourth relay lens 112 extend outward. Since the light to be converted is converted into convergent light, the third relay lens 111
Light emitted from the liquid crystal panel 121 can be efficiently guided to the red liquid crystal panel 121.

The three liquid crystal panels 119, 120, 121
Is transmitted to the color combining optical device 122 and is combined into one light. The color synthesizing optical device 122 is the same as that shown in FIG.
3. It comprises a red reflecting dichroic mirror 124 and an incident angle selective mirror 125. Color synthesis optical device 1
The light combined into one by the 22 passes through the projection lens 126 and reaches the screen. Thus, the optical images formed on the three liquid crystal panels 119, 120, and 121 are enlarged and projected on the screen by the projection lens 126.

Three liquid crystal panels 119, 120, 121
Is a transmission type polymer dispersed liquid crystal panel. A nematic liquid crystal and a polymer are mixed between two glass substrates so that the refractive index of the nematic liquid crystal with respect to ordinary light is equal to the refractive index of the polymer. A transparent electrode is provided on the liquid crystal layer side of the glass substrate. When no voltage is applied, light is scattered because the liquid crystal molecules are oriented in random directions and the refractive index of the liquid crystal molecules is not equal to the refractive index of the polymer with respect to the light perpendicularly incident on the glass substrate. When a voltage is applied to the liquid crystal layer, the liquid crystal molecules are aligned perpendicular to the glass substrate, and the refractive index of the liquid crystal molecules becomes equal to the refractive index of the polymer, so that light goes straight. Thus, by controlling the voltage applied to the liquid crystal layer, an optical image can be formed on the liquid crystal layer as a change in the scattering state. The pupil of the projection lens 126 transmits only light having a certain divergence angle out of the light emitted from the liquid crystal panel, so that the optical image formed as a change in the scattering state is converted into an optical image of a change in luminance on the screen. Can be. The polymer-dispersed liquid crystal panel is efficient because a polarizing plate required for twisted nematic liquid crystal is not required.

The reference incident angle of the two dichroic mirrors 123 and 124 constituting the color synthesizing optical device 122 is 30.
°, the reference incident angles of the two dichroic mirrors 109 and 110 constituting the color separation optical device are also 30.
° can be. Since the color separation optical device has a small incident angle to the dichroic mirrors 109 and 110,
Red, green, and blue primary color light with good uniformity can be efficiently obtained. Further, as described above, the color combining device 122 also has a small PS difference of the cutoff wavelength and small dependence on the incident angle, so that the efficiency of the projection display device is high. Further, the color combining optical device 1
In No. 22, since the astigmatic difference is small even if the substrate thickness of the two dichroic mirrors 123 and 124 is increased, the reduction in resolution by the dichroic mirrors 123 and 124 is small. Also, since the optical path length of the color combining optical device is the same as the conventional one,
The projection lens will not be more expensive than before. Thus, it is possible to provide a low-cost, high-resolution projection display device with high light output.

(Embodiment 4) FIG. 9 shows a configuration of a projection display apparatus according to Embodiment 4 of the present invention. In FIG. 9, reference numeral 136 denotes a projection lens, 139 denotes a color separation / synthesis optical apparatus, and 146. , 147 and 148 are liquid crystal panels.

The lamp 132 and the concave mirror 13 constituting the light source
3, the filter 134 and the cold mirror 135 are the same as those shown in FIG. The light emitted from the light source is transmitted to a plane mirror 13 disposed at the center of the projection lens 136.
The light is reflected by the lens 7, passes through the rear group lens 138, enters the color separation / synthesis optical device 139, and is separated into red, green, and blue primary color lights. The color separation / synthesis optical device 139 is the same as that shown in FIG. 1, and includes a blue reflection dichroic mirror 140, a red reflection dichroic mirror 141, and an incident angle selective mirror 142. The primary color lights emitted from the color separation / synthesis optical device 139 are respectively
3, 144, 145, then the liquid crystal panel 146,
147 and 148.

Three liquid crystal panels 146, 147, 148
Are reflective liquid crystal panels using polymer-dispersed liquid crystal, and form an optical image as a change in the scattering state. Light emitted from each of the liquid crystal panels 146, 147, and 148 passes through the field lenses 143, 144, and 145, enters the color separation / synthesis optical device 139, is combined into one light, and then enters the projection lens 149. . An aperture 150 is arranged near the plane mirror 137 of the projection lens 149, and the aperture 150 causes the liquid crystal panels 146, 147,
The optical image with the changed light scattering state formed at 148 can be converted into an optical image with a change in luminance, and can be enlarged and projected on a screen.

The color separation / synthesis optical device 139 shown in FIG.
Has both color separation and color synthesis. Two dichroic mirrors 14 constituting the color separation / synthesis optical device 139
Since the reference incident angle of 0,141 is as small as 30 °, FIG.
As in the case of the projection type display device shown in (1), it is possible to provide an inexpensive projection type display device having high light output, high resolution, and high resolution.

The projection type display device shown in FIG.
A light valve that forms an optical image as a change in the scattering state,
A light valve that forms an optical image as a change in the direction of light reflection using a minute mirror, a light valve that forms an optical image as a change in the light distribution characteristic of reflected light using diffraction, and the like can be used.

(Embodiment 5) FIG. 10 shows a configuration of a projection display apparatus according to Embodiment 5 of the present invention. In FIG. 10, reference numeral 165 denotes a front polarizer, 166 denotes a polarizing beam splitter, and 170 denotes a polarizing beam splitter. Is a color separation / synthesis optical device, 17
1, 172 and 173 are liquid crystal panels and 174 is a projection lens.

The lamp 161 and the concave mirror 16 constituting the light source
2, the filter 163 and the cold mirror 164 are the same as those shown in FIG. The light emitted from the light source passes through the pre-polarizer 165 and enters the polarization beam splitter 166. The polarization beam splitter 166
A multilayer film 169 having polarization selectivity is attached to the joint surface between the two glass prisms 167 and 168, and transmits a P-polarized component and reflects an S-polarized component. The pre-polarizer 165 has the same configuration as the polarization beam splitter 166, and has a main plane (the multilayer film 1) of the polarization beam splitter 166.
The plane including the normal line of 69 and the optical axis) and the main plane of the pre-polarizer 165 are arranged to be orthogonal to each other. The light emitted from the polarization beam splitter 166 is transmitted to the color separation / synthesis optical device 1.
70, and is decomposed into red, green, and blue primary color lights, and the primary color lights are respectively used for red, green, and blue liquid crystal panels 171, 1.
72, 173. The color separation / synthesis optical device 170 is the same as that shown in FIG.

Each of the liquid layer panels 171, 172, and 173 is a reflection type liquid crystal panel having a reflection electrode and vertically aligned nematic liquid crystal, and forms an optical image as a change in birefringence according to a video signal. . The liquid crystal panel converts an incident S-polarized component into a P-polarized component depending on the magnitude of the birefringence.

Three liquid crystal panels 171, 172, 173
The light emitted from the light beam enters the color separation / synthesis optical device 170, is synthesized into one light, and is polarized by the polarization beam splitter 166.
, And the P-polarized component is transmitted and enters the projection lens 174. Thus, the liquid crystal panels 171, 172, 173
The optical image formed as a change in birefringence is enlarged and projected on a screen by a projection lens 174.

The front polarizer 165 is used to increase the contrast of the projected image. This is because a polarizing beam splitter generally has a P-polarized transmittance that is not close to 100%.
When the pre-polarizer 165 is not used, the light reflected and emitted from the polarization beam splitter 166 ideally needs to be only the S-polarized component, but the P-polarized component is mixed therein. By using the pre-polarizer 165, the P-polarized light component mixed with the light incident on the liquid crystal panel can be significantly reduced.

The two dichroic mirrors 140 and 141 of the color separation / synthesis optical device receive S-polarized light during color separation and P-polarized light during color synthesis. this is,
The color combining optical device 122 shown in FIG. 8 and the color separating / combining optical device 139 shown in FIG. 9 also have the common feature that the S-polarized light and the P-polarized light enter.

The projection type display device shown in FIG.
Since the color separation / synthesis optical device having the same configuration as that shown in the drawing is used, the projection display device having a large light output, a high resolution and a low cost, as in the case of the projection display devices shown in FIGS. Can be provided.

(Embodiment 6) FIG. 11 shows the configuration of an image pickup apparatus according to Embodiment 6 of the present invention. In FIG. 11, reference numeral 181 denotes a color separation optical apparatus, 185 denotes an image pickup lens, 186 and 187. , 188 are imaging devices.

The color separation optical device 181 has the same configuration as that shown in FIG. 7, and comprises an incident angle selective mirror 182, a red reflection dichroic mirror 183, and a blue reflection dichroic mirror 184. The light emitted from the subject enters the imaging lens 185, and the emitted light enters the color separation optical device 181 and is separated into red, green, and blue primary color lights, and then is sent to the corresponding imaging elements 186, 187, and 188. Incident.

Since the reference incident angles of the dichroic mirrors 183 and 184 constituting the color separation optical device are as small as 30 °, the reduction in resolution is small, and the flat type dichroic mirror is less expensive than the prism type dichroic mirror. Also, by using the incident angle selective mirror 182, the back focus of the imaging lens is shortened.
The imaging lens can also be configured at low cost.

[0063]

As described above, the color synthesizing apparatus of the present invention can reduce the angle of incidence on the dichroic mirror, so that the PS difference in spectral transmittance characteristics can be reduced, and the plane of the reflecting surface can be reduced. The astigmatism can be reduced even if the glass substrate is thickened in order to secure the degree, and the optical thin film is attached to both sides of the three glass substrates, so that the resolution is high, the efficiency is high, It is cheap. Also,
By using the incident angle selective mirror, it is possible to prevent the optical path length of the color synthesizing optical device from being lengthened, so that the projection lens used in combination is inexpensive.

The color separation optical device of the present invention also has a high resolution, a high efficiency, a short optical path length, and is inexpensive by the same operation as the color synthesis optical device.

By using the color synthesizing optical device of the present invention, it is possible to provide an inexpensive projection display device with high efficiency and high resolution. Further, by using the color separation optical device of the present invention, it is possible to provide a high-efficiency, high-resolution, and inexpensive imaging device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a configuration of a color combining optical device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram illustrating an example of a spectral transmittance characteristic of a blue reflection dichroic mirror used in the color combining optical device according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing an example of a spectral transmittance characteristic of a red reflection dichroic mirror used in the color combining optical device according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing an example of a spectral transmittance characteristic of an incident angle selective mirror used in the color combining optical device according to the first embodiment of the present invention.

FIG. 5 is a side sectional view showing a specific configuration of the color combining optical device according to the first embodiment of the present invention.

FIG. 6 is a plan view showing a specific configuration of the color combining optical device according to the first embodiment of the present invention.

FIG. 7 is a schematic configuration diagram illustrating a configuration of a color separation optical device according to a second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a configuration of a projection display apparatus according to Embodiment 3 of the present invention.

FIG. 9 is a schematic configuration diagram showing a configuration of a projection display device according to a fourth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a configuration of a projection display apparatus according to a fifth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram illustrating a configuration of an imaging device according to a fifth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram showing a configuration example of a polymer dispersed liquid crystal panel.

FIG. 13 is a schematic configuration diagram showing an example of a conventional projection display device.

FIG. 14 is a schematic configuration diagram showing an example of a conventional projection display device.

[Explanation of symbols]

41 Blue reflection dichroic mirror 42 Red reflection dichroic mirror 43 Incident angle selective mirror 71, 72, 73 Frame 82 Incident angle selective mirror 85 Red reflective dichroic mirror 90 Blue reflective dichroic mirror 102 Lamp 109, 110, 123, 124 Dichroic mirror 119, 120, 121 Liquid crystal panel 122 Color combining optical device 125 Incident angle selective mirror 126 Projection lens 132 Lamp 139 Color separation / combining optical device 140, 141 Dichroic mirror 142 Incident angle selective mirror 146, 147, 148 Liquid crystal panel 149 Projection lens 161 Lamp 165 Pre-polarizer 166 Polarizing beam splitter 170 Color separation / synthesis optical device 171, 172, 173 Liquid crystal panel 174 Projection lens 181 Color separation optical device 185 Imaging lens 182 Incident angle selective mirror 183, 184 Dichroic mirror 186, 187, 188 Image sensor

Claims (20)

[Claims] 1. A flat first dichroic mirror that transmits a first color light and reflects a second color light to synthesize a two-color synthesized light, and transmits the two-color synthesized light and transmits a third color light. A flat second dichroic mirror that reflects and combines the three-color combined light, and a flat incident angle selection that transmits the vertically incident three-color combined light and reflects the obliquely incident third-color light A color mirror, wherein the third color light is obliquely incident on the incident angle selective mirror, reflected by the second dichroic mirror, and vertically transmitted through the incident angle selective mirror. . 2. The color synthesizing optical device according to claim 1, wherein an angle between a normal line of the incident angle selective mirror and a normal line of the first dichroic mirror is not less than 25 ° and not more than 35 °. 3. The color synthesizing optical device according to claim 1, wherein an angle between a normal line of the incident angle selective mirror and a normal line of the second dichroic mirror is not less than 25 ° and not more than 35 °. 4. The color combining optical device according to claim 1, wherein the first dichroic mirror and the second dichroic mirror are arranged in a V-shape. 5. The color combining optical device according to claim 1, wherein the third color light is red light. 6. A flat incident angle selective mirror that transmits first color light, second color light, and third color light that are incident vertically and reflects the third color light that is incident obliquely, First
And a flat dichroic mirror that transmits the second color light and reflects the third color light, and a flat first dichroic mirror that transmits the first color light and reflects the second color light. And a second dichroic mirror.
Is vertically transmitted through the incident angle selective mirror and sequentially transmitted through the first and second dichroic mirrors, and the second color light is vertically transmitted through the incident angle selective mirror and is transmitted through the first dichroic mirror. The third color light is transmitted through the mirror, reflected by the second dichroic mirror, vertically transmitted through the incident angle selective mirror, reflected by the first dichroic mirror, and reflected by the incident angle selective mirror. Color separation optical device. 7. The color separation optical device according to claim 6, wherein an angle between a normal to the incident angle selective mirror and a normal to the first dichroic mirror is not less than 25 ° and not more than 35 °. 8. The color separation optical device according to claim 6, wherein an angle between a normal to the incident angle selective mirror and a normal to the second dichroic mirror is not less than 25 ° and not more than 35 °. 9. The color separation optical device according to claim 6, wherein the first dichroic mirror and the second dichroic mirror are arranged in a V-shape. 10. The color separation optical device according to claim 6, wherein the third color light is red light. 11. A light source that emits light containing red, green, and blue color components, color separation means for separating light emitted from the light source into three primary color lights of red, green, and blue; Three light valves, each of which receives light and forms an optical image by an electric signal, color combining means for combining light emitted from the three light valves into one light, and light emitted from the color combining means. And a projection lens for projecting an optical image formed on the light valve onto a screen, and using the color combining optical device according to claim 1 as the color combining means. 12. A color separation means comprising a first plate-shaped color separation dichroic mirror and a second plate-shaped color separation dichroic mirror, wherein said first color separation dichroic mirror emits light from a light source. From red, green and blue
12. The projection display apparatus according to claim 11, wherein colors are separated, and said second color separation dichroic mirror separates one color from two colors not separated by said first color separation dichroic mirror. 13. The projection display according to claim 11, wherein each of the two color separation dichroic mirrors constituting the color separation means is parallel to the second dichroic mirror of the color synthesizing optical device. 14. A light transmission means in an optical path from a second color separation dichroic mirror to a corresponding light valve,
The light transmitting optical unit includes an input part convergent lens, a central part convergent lens and an output part convergent lens, a first plane mirror disposed between the input part convergent lens and the central part convergent lens, A second plane mirror disposed between a central convergent lens and the output convergent lens, wherein the input convergent lens forms an image corresponding to a light source at the position of the central convergent lens, 12. The projection display according to claim 11, wherein the central convergent lens forms an image corresponding to the input convergent lens at the position of the output convergent lens. 15. The projection display device according to claim 11, wherein each of the three light valves is a polymer dispersed liquid crystal panel. 16. A light source that emits light containing red, green, and blue color components, three reflective light valves that form an optical image as a change in optical characteristics according to a video signal, and the light source Color separation / combination means for decomposing the emitted light into three primary color lights of red, green and blue, causing the primary light to enter the three light valves, and combining the light emitted from the three light valves into one light. 2. The color combining optical device according to claim 1, further comprising: a projection lens configured to project an optical image formed on the light valve onto a screen by receiving light emitted from the color separating / combining unit, and the color separating / combining unit. A projection display device using the same. 17. The projection display device according to claim 16, wherein each of the three light valves is a polymer dispersed liquid crystal panel. 18. The projection display device according to claim 16, wherein all of the three light valves are light valves that form an optical image as a change in a light reflection direction. 19. A light source that emits light containing red, green, and blue color components, three reflection-type light valves that form an optical image as a change in birefringence in accordance with a video signal, and And a polarization beam splitter that separates into a P-polarized component and a reflected S-polarized component, into which the outgoing light enters, and decomposes the S-polarized component into three primary colors of red, green, and blue, and applies the three light valves to the three light valves. A color separation / synthesis unit that emits primary color light and combines light emitted from the three light valves into one light; and a projection lens that projects an optical image formed on the light valve onto a screen, 2. The color separation / synthesis unit according to claim 1, wherein light emitted from the color separation / synthesis unit is incident on the polarization beam splitter, and a P-polarized light component included in the incident light goes straight and enters the projection lens. Projection display device using a composite optical device. 20. An image pickup device comprising: an image pickup element for forming an image corresponding to a subject; and a color separation optical device for separating light emitted from the image pickup lens into three primary color lights of red, green and blue. An imaging apparatus comprising: the color separation optical device according to claim 6 as the color separation optical device.