JP3139387B2 - Projection display device - 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 display device for mainly projecting an optical image formed on a light valve on a screen in an enlarged manner.

[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 well known. Have been. Recently, a projection type display device using a liquid crystal panel as a light valve has attracted attention.

In order to obtain a full-color, high-brightness, high-resolution projected image, a system in which three light valves are used for red, green, and blue, and a single projection lens is used for projection is often used. In this case, a color separation optical system that separates white light output from the light source into three colors of red, green, and blue, and a color combining optical system that combines the three colors into one again are required.

FIG. 13 shows a configuration example of a projection type display device in which both a color separation optical system and a color synthesis optical system are configured using a plate-like dichroic mirror. The white light output from the light source 1 is reflected by a total reflection mirror 2 and then separated into three primary colors of red, green and blue by a color separation optical system composed of dichroic mirrors 3 and 4 and a total reflection mirror 5. You. Each primary color light passes through the corresponding field lenses 6, 7, 8 and light valves 9, 10, 11 and then is combined into one by a color combining optical system composed of dichroic mirrors 12, 13 and a total reflection mirror 14. And projection lens 1
5, the image is enlarged and projected on a screen (not shown).

A configuration example of a projection type display device in which a color combining optical system is configured using a dichroic prism (FIG. 1).
4 (a) to 4 (c)).

The configuration shown in FIG. 14A is of a type in which two dichroic mirror surfaces of a color combining prism 36 have an X-shape. Output light from the light source 21 passes through a total reflection mirror 22 and is separated into three primary color lights by a color separation optical system including dichroic mirrors 23 and 24 and total reflection mirrors 25, 26 and 27. The color component that travels through the total reflection mirrors 26 and 27 has an illumination light path length (distance from the light source 21 to the light valves 33, 34, and 35) different from the other two color components. The relay lenses 28 and 29 are supplementarily arranged so that the colors are equivalently substantially equal to those having the same optical path length. The three primary color lights correspond to the corresponding field lenses 30, 31, 32,
After being transmitted through the light valves 33, 34, and 35 and combined into one by the color combining prism 36, the image is enlarged and projected on a screen (not shown) by the projection lens 37.

In the configuration shown in FIG. 14B, the two dichroic mirror surfaces and the total reflection surface of the color combining prism 52 have dichroic mirrors 12 and 13 and a total reflection mirror having the configuration shown in FIG. It is arranged in the same way as 14,
All the spaces through which light passes are prisms, and the entire prism is L-shaped. The output light from the light source 41 passes through a total reflection mirror 42 and is output to a dichroic mirror 4.
The light is separated into three primary color lights by a color separation optical system composed of 3, 44 and a total reflection mirror 45. The three primary color lights correspond to the corresponding field lenses 46, 47, 48 and the light valve 4
After being transmitted through 9, 50, and 51 and combined into one by a color combining prism 52, the image is enlarged and projected on a screen (not shown) by a projection lens 53.

In the configuration shown in FIG. 14C, two dichroic mirror surfaces and a total reflection surface of the color combining optical system are
(See FIG. 14B)
Two cube-shaped dichroic prisms 74 and 75
And a type in which one triangular prism-shaped total reflection prism 73 constitutes a color combining optical system. The output light from the light source 61 passes through a total reflection mirror 62, and becomes dichroic mirrors 63 and 6.
4. The light is separated into three primary color lights by a color separation optical system constituted by a total reflection mirror 65. The three primary color lights correspond to the corresponding field lenses 66, 67, 68 and the light valves 69, 7.
0, 71 and the dichroic prisms 73, 7
4. After being combined into one by the color combining optical system constituted by the total reflection prism 72, the image is enlarged and projected on a screen (not shown) by the projection lens 53.

[0009]

A color synthesizing optical system to be disposed between the three light valves and the projection lens is one type of a projection optical system for forming an optical image on the light valves on a screen. The dichroic mirror that constitutes the color synthesizing optical system, the tilt angle accuracy, position accuracy, and flatness of each reflecting surface of the total reflection mirror, and the astigmatism that occurs when the light passes through the dichroic mirror are directly screened. Determines the image quality of the upper projected image.

In the configuration shown in FIG. 13, since the dichroic mirrors 13, 14 and the total reflection mirror 12 constituting the color synthesizing optical system are all plate-shaped, the color synthesizing optical system is lightweight and low cost. There is an advantage that the optical characteristics of the dichroic mirrors 13 and 14 are relatively good in terms of color reproduction and color use efficiency.

However, when an impact is applied to the entire set, the dichroic mirrors 13, 14 and the total reflection mirror 1
There is a problem in that the respective reflection surfaces are mechanically deviated from the initial state, whereby the red, green, and blue optical axes are deviated from each other, and convergence deviation on the screen easily occurs.

Further, dichroic mirrors 13 and 14,
Since all of the total reflection mirrors 12 are plate-shaped, it is difficult to maintain good flatness accuracy. Typically,
The flatness required for the reflection surface of the color combining optical system is such that the maximum deviation amount within an effective range from an ideal plane is 2λ or less, preferably λ or less, where λ is the wavelength of incident light. Required. When the flatness is not good, a convergence shift or a deterioration in image formation performance causes a reduction in resolution. In particular, in the case of the dichroic mirrors 13 and 14, there is also a problem that the flatness changes with time due to the internal stress of the multilayer film formed on the substrate. To achieve the flatness, the plate thickness is increased. There is a need. However, increasing the plate thickness increases the astigmatic difference, which also causes a significant deterioration in resolution.

Further, in the configuration shown in FIG. 13, the space from the light valves 9, 10, 11 to the projection lens 15 is long, and the projection lens 15 needs to have a long back focus. In this case, the outer diameter of the projection lens 15, particularly on the side of the light valves 9, 10, and 11, is large, and the overall length of the projection lens 15 is increased, which leads to an increase in the cost of the projection lens.

Therefore, if the color synthesizing optical system uses a prism as in the configuration shown in FIGS. 14A to 14C, the angle accuracy and the position accuracy of the reflecting surface can be reduced by the processing of the prism. It depends only on the accuracy, and there is almost no convergence deviation due to impact after assembly of the set. Further, since the prism has a sufficient thickness, the required flatness of each reflecting surface can be relatively easily realized, and the flatness hardly changes with time. Astigmatism does not occur because the dichroic mirror surface is held by prisms having the same refractive index. Therefore, a high-resolution projection image without convergence deviation can be easily realized.

Further, since the space from the light valve to the projection lens is occupied by a material such as optical glass having a higher refractive index than air, the air-equivalent optical path length should be shorter than that of the configuration shown in FIG. And the projection lens can be made compact.

As described above, by forming the color combining optical system by the prism, the above-mentioned problem which occurs in the structure shown in FIG. 13 can be solved.

However, in each of the configurations shown in FIGS. 14A to 14C, the reference incident angle of light incident on the dichroic mirror surface of the color combining optical system is 45 °, which is a dichroic prism. In some cases, it is disadvantageous in terms of color reproducibility and color use efficiency as compared with a plate-shaped dichroic mirror.

As an example, the spectral transmittance of the dichroic mirror of the color synthesizing prism 36 having the configuration shown in FIG. 14 (a) is shown in FIGS. 15 (a), (b), 16 (a), (b). ). The vertical axis of the graph represents transmittance, and the horizontal axis represents wavelength.
FIGS. 15 (a) and 16 (a) show the spectral transmittance (red reflection blue green transmission) of one of the two dichroic mirror surfaces arranged in an X-shape, and FIG. 15 (b) FIG.
(b)) represents the other spectral transmittance (blue reflection green red reflection). (FIGS. 15 (a) and (b)) show the spectral transmittances of S-polarized light, P-polarized light and natural light at a reference incident angle of 45 °, and (FIGS. 16 (a) and (b)) the standard incident angles of natural light. It shows the spectral transmittance for the case of 45 ° and the case of ± 5 ° in air conversion from the reference incident angle.

First, as can be seen from FIGS. 15 (a) and (b), the separation width of the 50% transmittance wavelength (hereinafter, half-value wavelength) of S-polarized light and P-polarized light is very large in any of the spectral characteristics. . When performing color separation or color synthesis, it is advantageous that the spectral curve between the reflection wavelength band and the transmission wavelength band is as sharp as possible in order to achieve both color reproduction and color use efficiency. Therefore, in the case of the spectral characteristics shown in FIGS. 15A and 15B, in a system using only linearly polarized light, the spectral characteristic of S-polarized light may be used. In this case, looking at the wavelength widths at which the transmittance is 90% and 10% as one index, all of them are 60 nm or more, and it is impossible to realize performance with good color reproducibility and high color use efficiency. It will be difficult.

Next, as can be seen from FIGS. 16 (a) and 16 (b), the incident angle dependency is large, which causes color unevenness of the projected image. In the case of a dichroic prism, the reference incident angle must be at least 35 ° or less, desirably 30 ° or less in order to have the same incident angle dependence as a plate-like dichroic mirror (FIG. 14).
Since the configurations shown in (a) to (c) are all 45 °, it is difficult to remove the color unevenness of the projected image while maintaining the color use efficiency of the projected image.

As means for solving the problem of the structure shown in FIG. 13 and the problem of the structure shown in (14 (a) to (c)), the structure shown in FIG. For example, it is disclosed in JP-A-63-31892. Light source 81
Is split into three primary color lights by a color separation optical system including dichroic mirrors 83 and 84 and mirrors 85, 86 and 87 via a lens 82. The three primary color lights pass through the corresponding condenser lenses 88, 89, 90 and the liquid crystal panels 91, 92, 93, respectively, and thereafter, the color combining prism 94
And are enlarged and projected by the projection lens 95. As the color combining prism 94, Japanese Patent Publication No. 38-237
No. 24 discloses a type constituted by a combination of three prisms having an air layer. If this type of prism is used, the angle of light incident on the surfaces of the two dichroic mirrors arranged in a V-shape can be made smaller than 45 °, and is shown in FIGS. 14 (a) to (c). Since the problem of the spectral characteristics of the configuration can be solved, and the prism is used, the degradation of the image quality of the projected image due to the use of the plate-like dichroic mirror as shown in FIG. 13 can also be reduced.

However, in the case of the structure shown in FIG. 17, it is necessary to adjust the air layer sufficiently thin and sufficiently uniform (with high accuracy of the parallelism of the prism interface on both sides of the air layer) in terms of assembling the prism. This leads to a significant cost increase. When the air layer is thick, the astigmatism that occurs degrades the resolution of the projected image, and when the air layer is not sufficiently uniform, the parallelism between the light entrance surface and the light exit surface of the prism causes the resolution degradation of the projected image. Becomes

[0023]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a high-brightness, high-quality liquid crystal projection display device.

Further, the projection type display device of the present invention comprises: a light generating means for radiating natural light containing three primary color components; a color separating means for decomposing the radiated light of the light generating means into three primary color lights;
The three primary color lights enter, modulate the primary color lights to form an optical image, three image forming units, a color combining unit that combines the output lights from the three image forming units into one, and a color combining unit. Projecting means for projecting the combined light, wherein the color synthesizing means comprises three prism members having two joining surfaces, and each of the two joining surfaces has a first dichroic in order from the projection means side. A mirror and a second dichroic mirror are formed, and an angle θ ₁ of light incident on the first dichroic mirror is not less than 20 ° and not more than 40 °, and
The angle θ ₂ of light incident on the dichroic mirror is 25
゜ 35 ° or less, and θ ₁ and θ ₂ satisfy the following conditions
And the light output from the projection lens is natural light.
It is.

[0025]

(Equation 5)

According to the projection display device of the present invention, light generating means for radiating natural light containing three primary color components, color separating means for decomposing light emitted from the light generating means into three primary color lights, and three primary colors are provided. Light enters and modulates primary color light to form an optical image 3
And a color synthesizing unit for synthesizing output lights from the three image forming units into one, and a projection unit for projecting the light synthesized by the color synthesizing unit.
A first dichroic mirror and a second dichroic mirror are formed on the two joining surfaces in this order from the side of the projection means. The angle θ ₁ is 20 ° or more and 40 ° or less, the angle θ ₂ of light incident on the second dichroic mirror is 25 ° or more and 35 ° or less, and θ ₁ and θ ₂ satisfy the condition of (Equation 5). The three image forming units are fixed so as to be optically coupled to the light incident surfaces of the color synthesizing unit, respectively, and the light output from the projection lens is natural light.

According to the projection display device of the present invention, light generating means for radiating natural light containing three primary color components, color separating means for decomposing light emitted from the light generating means into three primary color lights, and three primary colors are provided. Light is incident, three image forming means for modulating the primary color light to form an optical image, a color combining means for combining output lights from the three image forming means into one, and a color combining means. Projection means for projecting the reflected light, wherein the color separation means and the color synthesis means both enter the first dichroic mirror in which the angle θ ₁ of the incident light is 20 ° or more and 40 ° or less. the second dichroic mirror angle theta ₂ of the light is 35 ° or less than 25 °, a prism having at least two dichroic mirror surface, theta
₁ , θ ₂ satisfies the condition of (Equation 5), and the three primary color lights are configured such that the optical path lengths from the light generating means to the projecting means are substantially equal to each other, and the light output from the projection lens is
It is natural light .

A projection display apparatus according to the present invention comprises a light generating means for radiating natural light containing three primary color components, and a color separation for decomposing light emitted from the light generating means into three primary color lights and recombining them. Synthesizing means, three reflective image forming means for modulating each of the three primary color light beams incident thereon to form an optical image, and a projection means for projecting the output light synthesized by the color separation / combining means into one. Wherein the color separation / combination means comprises: a first dichroic mirror having an incident light angle θ ₁ of 20 ° or more and 40 ° or less; and an incident light angle θ
₂ is a prism body having at least two dichroic mirror surfaces of a second dichroic mirror in which 25 ° or more and 35 ° or less, and θ ₁ and θ ₂ satisfy the condition of (Equation 5).
Satisfied, the three primary color lights are configured such that the optical path lengths from the light generation means to the projection means are substantially equal to each other.

[0029]

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

(Embodiment 1) (FIG. 1) shows an example of the configuration of a projection type display apparatus of the present invention, wherein 101 is a light source as light generating means, 104 and 105 are dichroic mirrors, and 103 and 106. , 107 and 108 are total reflection mirrors, 114, 115 and 116 are liquid crystal panels as image forming means, 117 is a three-color synthesizing prism as color synthesizing means, 118 is a projection lens as projection means, and dichroic mirrors 103 and 105 and the total reflection mirror 10
6, 107 and 108 constitute a color separation optical system as color separation means.

The light source 101 is composed of a discharge lamp such as a metal halide lamp, and a concave mirror having a cold mirror which transmits infrared light of light emitted from the lamp and reflects visible light, and is substantially parallel to the concave mirror. Light is output.

The red, green, and blue 3 output from the light source 101
Natural light, including primary color light, enters the dichroic mirror 104 at an angle of 44 ° through an ultraviolet cut filter that reflects ultraviolet light and transmits visible light, and a total reflection mirror 103. The blue light is reflected by the dichroic mirror 104, and the green light and the red light are transmitted and enter the dichroic mirror 105 at an angle of 38 °. The red light is reflected by the dichroic mirror 105 and the green light is transmitted. As described above, the white light is separated into three primary color lights by the two dichroic mirrors 104 and 105. The blue light, the red light and the green light that have been decomposed are respectively passed through the total reflection mirror 106 to the blue light, to the field lens 111, to the red light to the field lens 112, to the relay lens 109, to the green light into the total reflection mirror 107, and to the relay. The light enters a field lens 113 via a lens 110 and a total reflection mirror 108. Further, the three primary color lights correspond to the corresponding field lenses 111, 112, 113 and the liquid crystal panel 11 respectively.
After passing through 4,115,116, the three-color combining prism 1
It is incident on 17. The three-color combining prism 117 combines the three primary color lights into one, and combines the combined light into a projection lens 118.
Incident on. Of the light modulated by the liquid crystal panels 114, 115, and 116, most of the scattered light enters the outside of the effective portion of the optical system and is shielded, and the light that goes straight passes through the projection lens 118 and passes through the screen (see FIG. (Not shown).
The optical image formed as a change in the scattering characteristics on the liquid crystal panels 114, 115, and 116 is enlarged and projected on the screen by the projection lens 118.

From the light source 101 to the liquid crystal panels 114 and 11
The illumination light path long distance up to 5,116 is set so that blue light and red light are equal.

Since the illumination light path length of the green light is different from the illumination light path lengths of the blue light and the red light, the illuminance distribution on the screen is equivalently substantially equal to the case where all three colors have the same optical path length. Relay lenses 107 and 108 are additionally provided in the optical path of the green light.

Field lenses 111, 112, 113
Are arranged such that the illumination light is focused on the entrance pupil of the projection lens in order to use the illumination light efficiently.

The liquid crystal panels 114, 115, and 116 use, as the liquid crystal, a polymer dispersed liquid crystal (hereinafter, referred to as a PD liquid crystal) that forms an optical image by changing a light scattering characteristic according to a video signal. When a PD liquid crystal is used, natural light can be used. Therefore, a twisted nematic liquid crystal that uses only one linearly polarized light to form an optical image by changing the optical rotation, and a polarizing plate as a polarizer and analyzer is indispensable. (TN liquid crystal), it is possible to display a projection image with a remarkably high brightness. Accordingly, in the projection display device shown in FIG. 1, natural light is emitted from the projection lens 118.

Here, the operation of the PD liquid crystal panel will be briefly described with reference to FIGS. 2 (a) and 2 (b).

In the polymer 125, a liquid crystal in the form of droplets (hereinafter referred to as a liquid crystal 124) is dispersed. A TFT (not shown) or the like is connected to the pixel electrode 122, and TF
When T is turned on and off, a voltage is applied to the pixel electrode 122, and the direction of liquid crystal alignment on the pixel electrode 122 is changed to modulate light. When no voltage is applied as shown in FIG. 2 (a), each liquid crystal 124 is oriented in an irregular direction. In this state, a difference in refractive index occurs between the polymer 125 and the water-droplet liquid crystal 124, and the incident light is scattered.

Here, as shown in FIG. 2B, when a voltage is applied between the counter electrode 123 and the pixel electrode 122, the directions of the liquid crystal molecules are aligned. If the refractive index when the liquid crystal molecules are aligned in a certain direction is previously set to the refractive index of the polymer 125, incident light goes straight without scattering.

Here, a method of manufacturing a PD liquid crystal panel will be described. As the polymer 125, a photocurable resin,
In particular, UV-curable resin (hereinafter referred to as UV
Resin) is usually used. The array substrate 121 and the opposing substrate 126 are held at a fixed interval. Fine beads are often used as the holding means. Note that P
It is basically unnecessary to form an alignment film on a D liquid crystal panel.
A solution in which an uncured UV resin component and a liquid crystal component are mixed (hereinafter, referred to as a mixed solution) is injected between the array substrate 121 and the counter substrate 126. Next, the mixed solution is irradiated with ultraviolet light. Then, the UV resin of the mixed solution is cured, and the resin component and the liquid crystal component undergo phase separation. When the amount of liquid crystal is small, the liquid crystal becomes the water droplet liquid crystal 124 as shown in FIG.
The water-drop liquid crystal 124 is continuous.

Next, the three-color combining prism 117 in the configuration shown in FIG. 1 will be described with reference to FIG.

The three-color combining prism 117 includes a first prism 131 and a first prism 131 in this order from the projection lens 118 side in FIG.
The three prisms of the second prism 132 and the third prism 133 are joined. The three prisms are made of polished optical glass and have the same refractive index. On each joint surface, a first dichroic mirror 134 and a second dichroic mirror 135 are formed.

The green light incident on the incident surface 136 is totally reflected once on the exit surface 139, is incident on the first dichroic mirror 134 at an incident angle θ ₁ , is reflected again, and is reflected again.
Emitted from 39. The blue light incident on the incident surface 137 is
After being incident on the second dichroic mirror 135 at an incident angle θ ₂ , it is reflected, passes through the first dichroic mirror 134, and exits from the exit surface 139. The red light incident on the incident surface 138 is reflected by the second dichroic mirror 135 and the first
Sequentially pass through the dichroic mirror 134 of the
Emitted from 39.

Here, both the incident angle θ ₁ and the incident angle θ ₂ can be set smaller than 45 ° by adopting the prism configuration shown in FIG. 3 and good spectral characteristics can be obtained. Further, the three-color combining prism 117 can be made compact as a whole.

As the range of the incident angle to be set, the incident angle θ
₁ is between 20 ° and 40 °, incident angle θ ₂ is between 25 ° and 35
゜ The following is desirable.

When the incident angle θ ₁ is less than 20 °, the first prism 131 becomes extremely long in the direction perpendicular to the optical axis 140, and the color combining prism 117 and the projection type display shown in FIG. The device cannot be made compact. When the incident angle θ ₁ is 40 ° or more, the spectral characteristic of the dichroic prism with the reference incident angle of 45 ° is close to that of the dichroic prism. Caused problems.

When the incident angle θ ₂ is 25 ° or less,
The incident angle θ ₁ may be 40 ° or more, and when the incident angle θ ₂ is 35 ° or more, the incident angle θ ₁ may be 20 ° or more.

More preferably, when the incident angle θ ₁ is 20 ° or more and 30 ° or less and the incident angle θ ₂ is 25 ° or more and 30 ° or less, better results are obtained in both spectral characteristics and compactness.

The second prism 132 and the third prism 1
33 may have the same shape. By doing so, the second prism 132 and the third prism 1 can be used in the prism processing.
33 can be produced with the same processing jig, which is advantageous for cost reduction.

In this case, the relationship between the incident angle θ ₁ and the incident angle θ ₂ can be expressed by the following equation.

[0051]

(Equation 6)

Therefore, the reference incident angles of the incident angles θ ₁ and θ ₂ may be determined under the conditions satisfying the expression (6) and within the above-mentioned angle range. In the present embodiment shown in FIGS. 1 and 3, the reference incident angles are set such that the incident angle θ ₁ is 26 ° and the incident angle θ ₂ is 32 °.

(FIGS. 4A and 4B), (FIGS. 5A and 5B)
FIG. 9 shows the spectral transmittance characteristics of the first dichroic mirror 134 and the second dichroic mirror 135. FIG. (FIG. 4
(a)) and (FIG. 5 (a)) show the first dichroic mirror 1
The spectral transmittance of No. 34 (FIG. 4 (b)) and (FIG. 5 (b)) are the second.
Represents the spectral transmittance of the dichroic mirror 135,
(FIGS. 4A and 4B) show the respective spectral transmittances of S-polarized light, P-polarized light and natural light, and FIGS. 5A and 5B show the incident angle dependence of the natural light spectral transmittance. ing.

Since the first dichroic mirror reflects green light, there are two half-value wavelengths and the half-value wavelength on the short wavelength side is 49
The half-value wavelength at 5 nm and the longer wavelength side is 585 nm.
Also, the second dichroic mirror 135 that reflects blue light
Has a half-value wavelength of 540 nm.

First, as can be seen from the graphs shown in FIGS. 4A and 4B, since the reference incident angle is smaller than the spectral characteristics shown in FIGS. 15A and 15B, First dichroic mirror 134, second dichroic mirror 135
In both cases, the wavelength separation width at the half-value wavelength of the S-polarized light and the P-polarized light is reduced, and the reflection wavelength band when natural light is used can be satisfactorily secured. Therefore, even if the light emitted from the three-color combining prism 117 is natural light, a projected image having good color reproducibility and good color use efficiency can be displayed.

In particular, the dichroic mirror 134 has a reference incident angle of 26 °,
Since it is even smaller than 2 ゜, the wavelength separation width at the half-value wavelength of S-polarized light and P-polarized light can be further suppressed. That is, if the first dichroic mirror 134 reflects green light, no green light is incident on the second dichroic mirror 135.
If the half-value wavelength of the second dichroic mirror 135 is set to an intermediate wavelength between red and blue (around 540 nm), the second dichroic mirror 135 can be used even if the reference incident angle is larger than that of the first dichroic mirror 134. Of the S-polarized light and the P-polarized light, the influence of the increase in the half value wavelength separation width and the incident angle dependency are practically negligible. Further, by doing so, the half-value wavelength tolerance of the second dichroic mirror 135 can be set wider than that of the first dichroic mirror, which is advantageous in terms of yield.

Next, as can be seen from the graphs shown in FIGS. 5A and 5B, the first dichroic mirror 134 is compared with the spectral characteristics shown in FIGS. 16A and 16B. And the second dichroic mirror 135 have reduced incident angle dependence. Therefore, it is possible to display a projected image with less color unevenness than the configuration shown in FIGS. 14 (a) and (b).

Further, the three-color combining prism 117 shown in FIG. 3 does not have an air layer unlike the color combining prism 94 having the configuration shown in FIG. There is no potential resolution degradation.
Therefore, it is easier to assemble the prism than the color synthesizing prism 94 in which the assembly accuracy of the air layer is required (FIG. 17), which is advantageous in terms of productivity and cost.

Here, the dichroic mirror 104 and the dichroic mirror 105 constituting the color separation optical system having the configuration shown in FIG. 1 have the reference incident angles of the incident light at 44 ° and 38 °, respectively, and both are 45 °.て い る The following is assumed. By doing so, the entire set can be made compact. In addition, in the plate-shaped dichroic mirrors 104 and 105, the smaller the reference incident angle is, the more advantageous the spectral characteristics are in terms of the S-polarized light and the half-wavelength separation width of the P-polarized light and the incident angle dependence.

As described above, since the projection type display apparatus of the present invention uses the three-color combining prism having the configuration shown in FIG. 3 for the color combining optical system, the plate-like configuration shown in FIG. The problems of convergence shift and resolution degradation that occur when the dichroic mirror is used, and the cost increase of the projection lens due to the long bark focus, can be solved, and (FIGS. 14A and 14B). The problem of the deterioration of the spectral characteristics of the dichroic mirror, which occurs when the dichroic prism whose reference incident angle to the dichroic mirror is 45 ° is used, and the air layer of the dichroic prism having the air layer shown in FIG. This can solve the cost increase or the resolution degradation caused by the above. Therefore, the projection display device of the present invention can reproduce color with high resolution,
A projection image with good color use efficiency can be easily realized.

The arrangement shown in FIGS. 1 and 3 is such that the first dichroic mirror 134 reflects green light, the second dichroic mirror reflects blue light, and the color separation optical system is configured accordingly. The dichroic mirror 104 performs blue reflection and the dichroic mirror 105 performs red reflection. However, each color arrangement of color separation and color composition may be another method.

For example, the first dichroic mirror 13
4 is blue reflection, the second dichroic mirror 135 is green reflection, the dichroic mirror 104 of the color separation optical system is green reflection, and the first dichroic mirror 134 and the second dichroic mirror when the dichroic mirror 105 is red reflection. 135 (FIG. 6A,
(b)) and (FIGS. 7 (a) and 7 (b)).

(FIG. 6 (a)) and (FIG. 7 (a)) show the spectral transmittance of the first dichroic mirror 134, (FIG. 6 (b))
FIG. 7B shows the spectral transmittance of the second dichroic mirror 135, and FIGS. 6A and 6B show the spectral transmittances of S-polarized light, P-polarized light, and natural light, respectively. (a),
(b)) shows the incident angle dependence of the natural light spectral transmittance.

The half-wavelength of the first dichroic mirror that reflects blue is 495 nm, and the second dichroic mirror 135 that reflects green is 585 nm.

In this case, since the two dichroic mirrors are configured by one-color reflection, there is an advantage that the half-value wavelength control of the multilayer film is easy to process.

In this case, too, as can be seen from the graphs shown in FIGS. 6A and 6B, the first dichroic is different from the spectral characteristics shown in FIGS. 15A and 15B. Mirror 13
4. Both S-polarized light of the second dichroic mirror 135,
The wavelength separation width at the half-value wavelength of the P-polarized light is reduced, and the reflection wavelength band when natural light is used can be secured well.

As can be seen from the graphs shown in FIGS. 5 (a) and 5 (b), the incident angle dependence is also the same (FIG. 1).
6 (a) and 6 (b)), the first dichroic mirror 134 and the second dichroic mirror 1 are compared with each other.
35 are both reduced.

As described above, in the present embodiment, (FIG. 3)
Two examples of spectral characteristics of the three-color combining prism shown in FIG.
Even if the arrangement of the three colors of red, blue, and green is still another combination, it is possible to secure the advantage with respect to the spectral characteristics of the prism having the reference incident angle of 45 °.

In this embodiment, the reference incident angle to the first dichroic mirror is set to 26 ° and the reference incident angle to the second dichroic mirror is set to 32 °. If so, another combination of the reference incident angles may be used.

Dichroic mirror 10 of color separation optical system
In the present embodiment, the reference incident angles are set to 44 ° and 38 ° for 4,105, however, other combinations of the reference incident angles may be used as long as they are 45 ° or less.

The same applies to the following embodiments with respect to the color arrangement of the three colors of the three-color combining prism and the color separation optical system, and the reference angle of incidence on the dichroic mirror surface.

(Embodiment 2) The configuration of the projection type display apparatus shown in FIG. 8 is such that liquid crystal panels 114, 115 and 116 are fixed to the entrance surface of a three-color synthesizing prism 117, respectively. , And the arrangement angle etc. (Figure 1)
Is the same as that shown in FIG.

By fixing the liquid crystal panels 114, 115, and 116 to the surface of the incident surface of the three-color synthesizing prism 117, unnecessary reflected light due to interface reflection with air is reduced and the contrast is improved. In this case, each liquid crystal panel 11
4, 115 and 116 are optically coupled to the three-color combining prism 117 by an optical coupling agent.

Examples of the optical binder include a transparent adhesive such as an acrylic or epoxy resin, a gel containing a silicone resin, and a liquid such as ethylene glycol.
Many of these optical coupling agents have a refractive index close to the refractive index of the substrate of the display panel and are practically sufficient. Specifically, it is a transparent silicone resin KE1051 manufactured by Shin-Etsu Chemical Co., Ltd., and has a refractive index of 1.40. This is supplied as two kinds of liquids. When the two liquids are mixed and left at room temperature or heated, they are cured into a gel by an addition polymerization reaction.

In the case of using any of the optical binders, if there is an air layer between the counter substrate and the object to be stuck as described above, image quality abnormality occurs there, so it is necessary to exclude the air layer. is there.

Each of the liquid crystal panels 114, 115 and 116 has 3
Regarding the effect when the color combining prism 117 is fixed with an optical binder, the liquid crystal panels 114 and 11 shown in FIG.
This will be described below with reference to the operation principle diagrams 5 and 116.

When the liquid crystal panels 114, 115, and 116 are not fixed, the incident light enters from the array substrate 121 side and is scattered by the droplet liquid crystal 124 of the polymer 124 layer. Part of the scattered light is reflected at the interface of the opposing substrate 126 with the air, and again enters the polymer 125 layer. The incident light is scattered again by the water droplet liquid crystal 124 (referred to as secondary scattering).
Then, part of the scattered light exits from the counter substrate 126. The emitted light enters a projection lens and is projected on a screen. The emitted light due to the secondary scattering is a factor that significantly deteriorates the contrast performance of the projected image.

Therefore, the liquid crystal panels 114, 115, 11
6 is fixed to the three-color synthesizing prism 117 via an optical coupling agent, whereby an interface between the liquid crystal panels 114, 115, and 116 and the three-color synthesizing prism 117 where unnecessary reflected light is generated can be optically removed. Contrast deterioration can be prevented.

Further, a light absorbing film is applied to an invalid area of the three-color synthesizing prism 117. By doing so, most of the scattered light enters the light absorbing film and is absorbed,
Returning to the liquid crystal panels 114, 115, and 116 again, almost no secondary scattering occurs. Therefore, the display contrast is further improved, and the liquid crystal panel 11
Since there is no reflected light at the interface between the 4, 115, 116 and the three-color combining prism, blurring of pixels due to irregular reflection and reduction of the window contrast are also eliminated.

In this case, the liquid crystal panels 114 and 11
5 and 116 are fixed to the three-color combining prism 117, so that the liquid crystal panels 114, 115 and 116 are adjusted after assembly.
The convergence shift due to the mechanical shift of the position is not caused.

As described above, the configuration shown in FIG. 8 is used when the liquid crystal panels 114, 115, and 116 having the configuration shown in FIG. 1 are fixed to the three-color combining prism 117 in order to further improve the contrast performance. However, the three-color combining prism 117 is the same as that shown in FIG. 3, and the effect of using this prism in the color combining optical system is exactly the same as that of the first embodiment.

(Embodiment 3) The projection display apparatus shown in FIG. 9 uses a prism having the configuration shown in FIG. 3 for the color separation optical system similarly to the color synthesis optical system, and It is a perspective view of the structure at the time of making the illumination optical path length equal to green.

Reference numeral 141 denotes a light source as light generation means;
Denotes a three-color separating prism, 153, 154, and 155 denote liquid crystal panels as image forming means; 156, a three-color combining prism as color combining means; and 157, a projection lens as projection means.

The liquid crystal panels 153, 154, and 155 use a polymer dispersed liquid crystal that forms an optical image as a change in light scattering characteristics in accordance with an image signal. The liquid crystal panels 114 and 155 shown in FIG. 115 and 116 are the same. The three-color separation prism 143 and the three-color synthesis prism 156 are the same as the three-color synthesis prism 117 shown in FIG.

The light source 141 is composed of a discharge lamp such as a metal halide lamp, and a concave mirror having a cold mirror which transmits infrared light of the light emitted from the lamp and reflects visible light, and is substantially parallel to the concave mirror. Light is output.

The three colors red, green and blue output from the light source 141
Natural light including primary color light passes through the total reflection mirror 142 and
The light enters the color separation prism 143. Three-color separation prism 1
As for the three primary color lights separated by 43, the blue light passes through total reflection mirrors 144 and 147 and passes through the field lens 150.
The red light passes through the total reflection mirrors 145 and 148 to the field lens 151, and the green light passes through the total reflection mirrors 146 and 1.
The light enters the field lens 152 via 49. Further, the three primary color lights correspond to the corresponding field lenses 150, 151, 152 and the liquid crystal panel 15 respectively.
After passing through 3,154,155, the three-color combining prism 1
It is incident on 56. The three-color combining prism 156 combines the three primary color lights into one, and combines the combined light into a projection lens 157.
Incident on. The optical images formed on liquid crystal panels 153, 154, and 155 are enlarged and projected on a screen (not shown) by projection lens 157.

In the case of this configuration, the illumination light path long distance from the light source 141 to the liquid crystal panels 153, 154, and 155 becomes equal for all three colors, so that the color uniformity on the screen is used in the configuration shown in FIG. Relay lenses 109, 110
And the color separation optical system is configured by a prism, so that the entire set can be configured very compactly.

Since the three-color separating prism 143 and the three-color combining prism used are the same as the three-color combining prism 117 shown in FIG. 3, the spectral characteristics are also (FIG. 4A, FIG.
(b)) and (FIGS. 5 (a) and 5 (b)), and the convergence shift and resolution degradation that occur when the plate-shaped dichroic mirror shown in (FIG. 13) is used. It is possible to solve the problem of increasing the cost of the projection lens due to the long bark focus, and (FIG. 14A)
-(B)) and the problem of the deterioration of the spectral characteristics of the dichroic mirror which occurs when the dichroic prism shown in FIGS. 15 (a) and (b) whose reference incident angle to the dichroic mirror is 45 ° is used. In addition, the cost increase or the resolution degradation due to the air layer of the dichroic prism having the air layer shown in FIG. 17 can be solved at the same time. Therefore, the projection display apparatus of the present embodiment can also easily realize a projection image with high resolution, color reproduction, and good color use efficiency.

The three-color separation prism 143 disposed in the illumination light path does not require the flatness or angular accuracy of the dichroic mirror surface as much as the three-color synthesis prism 156. If an integrally molded product is used, the cost can be reduced. In addition, a container is composed of a glass substrate serving as an entrance window and an exit window and a frame body made of aluminum or the like, and a substrate serving as a color separation surface is inserted into the container, and the refractive index of glass is set in the space of the container. It may be filled with a liquid close to. As the liquid, a liquid containing ethylene glycol as a main component is desirable because it is excellent in optical performance (transparency, uniformity of refractive index, etc.), heat resistance, cold resistance and the like. Further, in addition to ethylene glycol, a transparent silicon resin or the like which is liquid at least at the time of assembly, but gradually becomes gel-like after the completion of assembly may be used. However, in these cases, the three-color separation prism 143 is used.
Is desirably substantially the same as or similar to the three-color combining prism 156.

(Embodiment 4) (FIG. 10), (FIG. 1)
The projection display devices shown in 1) and (FIG. 12) are both examples of the configuration of a projection display device using a reflection type image forming device, and the image forming device having the configuration shown in FIG. The light valve uses a polymer dispersed liquid crystal that forms an optical image as a change in light scattering characteristics in response to a signal. The image forming unit having the configuration shown in FIG. A reflection element that forms an optical image by controlling the tilt angle of a mirror, and the image forming unit having the configuration shown in FIG. 12 is a light valve that uses liquid crystal that forms an optical image as a change in birefringence. .

Hereinafter, the above-mentioned three configuration examples will be described with reference to the drawings. First, the projection display device shown in FIG. 10 uses a polymer-dispersed liquid crystal.
Is a light source as light generating means, 164 is a three-color separation / combination prism as color separation / combination means, 165, 166, 167
Denotes a liquid crystal panel as image forming means, and 169 denotes a projection lens as projection means.

The liquid crystal panels 165, 166, and 167 are reflection type panels using a polymer dispersed liquid crystal that forms an optical image as a change in light scattering characteristics according to a video signal. Also,
As the three-color separating / combining prism 164, the same one as the three-color separating / combining prism 117 shown in FIG. 1 is used.

The light source 161 is composed of a discharge lamp such as a metal halide lamp, and a concave mirror having a cold mirror that transmits infrared light of light emitted from the lamp and reflects visible light, and is substantially parallel to the concave mirror. Light is output.

The three colors of red, green and blue output from the light source 161
Natural light including primary color light enters the three-color separation / combination prism 164 via the total reflection mirrors 162 and 163. The three primary color lights separated by the three-color separation prism 164 are
Blue light is applied to the liquid crystal panel 165 and red light is applied to the liquid crystal panel 16.
6, green light enters the liquid crystal panel 167, respectively.
The three primary color lights correspond to the liquid crystal panel 16 respectively.
After being modulated by 5,166,167,
The light again enters the three-separation color combining prism 164. The three-color separation / combination prism 164 combines the three primary color lights into one,
The combined light enters the stop 168. Most of the light modulated as the scattered light is blocked by the stop 168, and the unmodulated light passes through the stop 168 and enters the projection lens 169. Thus, the optical image formed on the liquid crystal panels 165, 166, and 167 as a change in the scattering characteristics is enlarged and projected on a screen (not shown) by the projection lens 169.

Also in this configuration, the illumination light path long distance from the light source 161 to the liquid crystal panels 165, 166, 167 is three.
Since the colors are also equal, the color uniformity on the screen has the relay lenses 109 and 110 used in the configuration shown in FIG.
And the color separation optical system and the color synthesis optical system are constituted by one three-color separation / synthesis prism 164, so that the whole set can be made very compact.

The three-color separation / combination prism 164 (FIG. 3)
Since the same three-color synthesizing prism 117 shown in FIG. 4 is used, the spectral characteristics are also (FIGS. 4A and 4B) and (FIGS. 5A and 5B).
As shown in (b)), the convergence shift and resolution degradation that occur when the plate-shaped dichroic mirror shown in FIG. 13 is used, and the cost increase of the projection lens due to the long bark focus. (A) and (b) of FIG. 14 and FIG.
(a), (b)) the problem of the deterioration of the spectral characteristics of the dichroic mirror which occurs when the dichroic prism having the reference incident angle to the dichroic mirror of 45 ° is used, and FIG. The cost increase or the resolution degradation due to the air layer of the dichroic prism having the air layer can be solved at the same time. Therefore, the projection display apparatus of the present embodiment can also easily realize a projection image with high resolution, color reproduction, and good color use efficiency.

In the case of the projection display using the polymer dispersed liquid crystal described in the above embodiment, (FIG. 1)
In (FIG. 8), (FIG. 9), and (FIG. 10), the traveling systems of the scattered light and the straight traveling light are not limited to these.
For example, a centrally shielded optical system that blocks a straight light component with a light shield and projects scattered light on a screen may be used.

Next, the projection type display device shown in FIG. 11 uses a reflection element in which reflection mirrors are arranged in a matrix. Reference numeral 171 denotes a light source as light generation means;
75 is a three-color separation / combination prism as color separation / synthesis means,
Reference numerals 176, 177, and 178 denote liquid crystal panels as image forming means, and 179 denotes a projection lens as projection means.

The light valves 176, 177, 178
This is a reflection type panel using a polymer dispersed liquid crystal in which an inclination angle of each minute reflection mirror arranged in a matrix is changed in accordance with a video signal to form an optical image. Also in this case, the same three-color separating / combining prism 175 as the three-color separating / combining prism 117 shown in FIG. 1 is used.

The light source 171 is composed of a discharge lamp such as a metal halide lamp, and a concave mirror having a cold mirror that transmits infrared light of light emitted from the lamp and reflects visible light, and is substantially parallel to the concave mirror. Light is output.

The three colors of red, green and blue output from the light source 171
Natural light including primary color light is reflected by total reflection mirrors 172, 173,
The light enters the three-color separation / combination prism 175 via the field lens 174. Of the three primary color lights separated by the three-color separation prism 175, blue light is converted into a liquid crystal panel 176.
Then, red light enters the liquid crystal panel 177, and green light enters the liquid crystal panel 178. The three primary color lights are modulated by the corresponding liquid crystal panels 176, 177, and 178 and then reflected, and are again reflected in the three-separated color combining prism 1.
75. The three-color separation / combination prism 175 combines the three primary color lights into one again, and the combined light enters the projection lens 179. Liquid crystal panels 176, 177, 17
The optical image formed by the change in the reflection angle of light on 8 is
The image is enlarged and projected on a screen (not shown) by the projection lens 179.

In the case of this configuration as well, the illumination light path long distance from the light source 171 to the liquid crystal panels 176, 177, 178 is 3
Since the colors are also equal, the color uniformity on the screen has the relay lenses 109 and 110 used in the configuration shown in FIG.
And the color separation optical system and the color synthesis optical system are constituted by one three-color separation / synthesis prism 175, so that the whole set can be made very compact.

The three-color separation / combination prism 175 is
Since the same three-color combining prism 117 shown in FIG. 3 is used, the spectral characteristics are also shown in FIGS. 4A and 4B and FIGS. 5A and 5B. As a result, it is possible to solve the problems of convergence deviation and resolution degradation that occur when the plate-shaped dichroic mirror shown in FIG. 13 is used, and further increase the cost of the projection lens accompanying the long bark focus. , (FIGS. 14A and 14B), and a dichroic prism generated when the dichroic prism shown in FIGS. 15A and 15B with a reference incident angle to the dichroic mirror of 45 ° is used. The problem of the deterioration of the spectral characteristics of the mirror and the high cost or resolution deterioration due to the air layer of the dichroic prism having the air layer shown in FIG. 17 can be solved at the same time. Therefore, the projection display apparatus of the present embodiment can also easily realize a projection image with high resolution, color reproduction, and good color use efficiency.

Next, the projection type display device shown in FIG. 12 uses a liquid crystal having birefringence, 181 is a light source as light generating means, 183 is a polarization beam splitter, and 184 is color separation / synthesis. A three-color separation / combination prism as means, 185, 186, and 187 are liquid crystal panels as image forming means, and 188 is a projection lens as projection means.

The light valves 185, 186, 187
This is a reflective panel using liquid crystal whose birefringence changes in accordance with a video signal to form an optical image. Examples of the liquid crystal material include a ferroelectric liquid crystal and a homeotropic liquid crystal. The polarizing beam splitter is formed by joining two prisms, and a multilayer film having polarization selectivity is formed on the joining surface. Also in this case, the three-color separating / combining prism 184 is the same as the three-color separating / combining prism 117 shown in FIG.
The same is used.

The light source 181 is composed of a discharge lamp such as a metal halide lamp, and a concave mirror having a cold mirror that transmits infrared light of light emitted from the lamp and reflects visible light, and is substantially parallel to the concave mirror. Light is output.

The three colors of red, green and blue outputted from the light source 181
Natural light including primary color light enters the polarization beam splitter 183 via the total reflection mirror 182. Of the natural light that has entered the polarizing beam splitter 183, P-polarized light passes through the polarizing beam splitter 183 as unnecessary light, and S-polarized light is reflected and enters the color separation / combination prism 184. Of the three primary color lights separated by the three-color separation prism 184, blue light enters the liquid crystal panel 185, red light enters the liquid crystal panel 186, and green light enters the liquid crystal panel 187. The three primary color lights that have become substantially linearly polarized light are reflected by the corresponding liquid crystal panels 186, 187, and 188 after being modulated into elliptically polarized light, and then enter the three-separated color combining prism 184 again. Three-color separation / combination prism 184
Combine the three primary color lights into one again, and the combined light again enters the polarizing beam splitter 183. Of the elliptically polarized light modulated by the liquid crystal panels 186, 187, and 188, the light converted to P-polarized light passes through the polarizing beam splitter 183 and enters the projection lens 188, and the S-polarized light not converted is reflected by the polarizing beam splitter 183. Then, the light advances to the light source 181 side. Thus, the optical image formed on the liquid crystal panels 185, 186, 187 by the change of the birefringence of the liquid crystal is enlarged and projected on a screen (not shown) by the projection lens 179.

In the case of this configuration as well, the illumination light path long distance from the light source 181 to the liquid crystal panels 186, 187, 188 is 3
Since the colors are also equal, the color uniformity on the screen has the relay lenses 109 and 110 used in the configuration shown in FIG.
And the color separation optical system and the color synthesis optical system are constituted by one three-color separation / synthesis prism 184, so that the entire set can be made very compact.

Further, the three-color separation / combination prism 184 is
Since the same one as the three-color combining prism 117 shown in FIG. 3 is used, the convergence deviation and the resolution degradation that occur when the plate-shaped dichroic mirror shown in FIG. This solves the problem of increasing the cost of the projection lens due to focusing.

Regarding spectral characteristics, in this case, since linearly polarized light is used, a dichroic mirror can be designed only with the spectral transmittance of S-polarized light. Therefore, there is no problem due to the large half-value wavelength width of the S-polarized light and the P-polarized light as shown in (FIGS. 14A and 14B). However, this occurs when a dichroic prism whose reference incident angle to the dichroic mirror shown in FIGS. 15A and 15B is 45 ° is used.
The solution of the problem of the incident angle dependence of the dichroic mirror is effective as in the above-described embodiment. (FIG. 17)
The cost increase or the degradation of resolution due to the air layer of the dichroic prism having the air layer shown in FIG. Therefore, the projection display apparatus of the present embodiment can also easily realize a projection image with high resolution, color reproduction, and good color use efficiency.

In all of the above embodiments,
Although a metal halide lamp is used as a light source, a mercury lamp, a xenon lamp, a halogen lamp, an electrodeless discharge lamp, or the like may be used as a light source.

[0112]

As described above, according to the present invention, when three light valves are used and one projection lens is used, convergence deviation, astigmatism, and resolution caused by the color combining optical system are generated. It is possible to provide a projection-type display device capable of displaying a projection image with good color uniformity, color reproducibility, and color use efficiency while eliminating deterioration, and has a very large effect.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a projection display device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation principle of a polymer-dispersed liquid crystal.

FIG. 3 is a configuration diagram of a three-color combining prism used in the projection display device of the present invention.

FIG. 4 is a spectral transmittance characteristic diagram of a three-color combining prism used in the projection display device of the present invention.

FIG. 5 is a spectral transmittance characteristic diagram of a three-color combining prism used in the projection display device of the present invention.

FIG. 6 is a spectral transmittance characteristic diagram of a three-color combining prism used in the projection display device of the present invention.

FIG. 7 is a spectral transmittance characteristic diagram of a three-color combining prism used in the projection display device of the present invention.

FIG. 8 is a schematic configuration diagram of a projection display device according to an embodiment of the present invention.

FIG. 9 is a perspective view of a projection display device according to an embodiment of the present invention.

FIG. 10 is a perspective view of a projection display according to an embodiment of the present invention.

FIG. 11 is a perspective view of a projection display device according to an embodiment of the present invention.

FIG. 12 is a perspective view of a projection display according to an embodiment of the present invention.

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

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

FIG. 15 is a spectral transmittance characteristic diagram of a color combining prism used in a conventional projection display device.

FIG. 16 is a spectral transmittance characteristic diagram of a color combining prism used in a conventional projection display device.

FIG. 17 is a schematic configuration diagram of a conventional projection display device.

[Explanation of symbols]

 101 light source 104, 105 dichroic mirror 103, 106, 107, 108 total reflection mirror 114, 115, 116 liquid crystal panel 117 three-color combining prism 118 projection lens

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-244613 (JP, A) JP-A-4-372922 (JP, A) JP-A-7-209621 (JP, A) JP-A-5-209621 66308 (JP, A) JP-A-5-100330 (JP, A) JP-A 5-249408 (JP, A) JP-A 5-127274 (JP, A) Japanese Utility Model Application Sho 62-37496 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 33/12 G02B 5/04 G02B 27/18 H04N 9/31

Claims (6)

(57) [Claims] 1. A light generating means for radiating natural light containing three primary color components; a color separating means for decomposing the radiated light of the light generating means into three primary color lights; Three image forming means for modulating the natural light to form an optical image; a color combining means for combining output lights from the three image forming means into one; and projecting the light combined by the color combining means. The color separation means is provided separately from the color synthesis means, and the color separation means and the color synthesis means each have an angle θ _{1 of} incident light of 20 ° or more. A first dichroic mirror of 40 ° or less, and an angle θ _{2 of} incident light of 25
A prism body having at least two dichroic mirror surfaces of a second dichroic mirror of not less than {35} and less, wherein θ ₁ and θ ₂ satisfy the following conditions; A projection display device, wherein the optical path lengths from the means to the projection means are substantially equal to each other, and the light output from the projection lens is natural light. (Equation 1) Wherein said angle θ1 is less than 20 ° or more 30 °, the angle θ2 is projection display apparatus according to claim 1, wherein a is less than or equal to 35 ° 30 ° or more. Wherein the color and prisms decomposing means, the projection display device of the prism body is each shape or claim 1 wherein the similar shape, of the color synthesizing means. 4. The image forming device according to claim 1, wherein the three image forming units have light scattering characteristics.
Using a polymer dispersed liquid crystal that forms an optical image as a change in
The light valve according to claim 1, wherein the light valve is a light valve.
Photographic display device. 5. A voltage is applied to the electrode of the polymer-dispersed liquid crystal.
When applied, it scatters the incident light and a voltage is applied to the electrodes.
When it is not applied, the incident light goes straight. Sign
A projection display device according to claim 4. 6. The three optical axes of the three image forming units
Transmitting or reflecting the first plane including the color separation means
The second plane including the three optical axes of the three primary color components is aligned with each other.
The three image forming means and the
2. A color separation means is provided.
The projection type display device according to the above.