JPH07287225A - Projection type color display device and illuminating device using it - Google Patents

Abstract

PURPOSE:To obtain uniform, high-contrast and high-luminance color projection display. CONSTITUTION:This projection type color display device is provided with a light source optical system provided with an elliptical mirror 12, a light source 11 set at the 1st focusing position of the mirror 12, a convex conical reflector 1 or a concave conical reflector set at the 2nd focusing position thereof, and a 1st diaphragm 17; a color separation means 141, six condensing lenses for RGB, a transmission and scattering type liquid crystal display element 15, a color synthesis means 142, a 2nd diaphragm 18, and a projection optical system 19. Thus, the directivity of the light source light is arranged by the convex or concave surface of the reflector 1 and efficiently made incident on the display element 15, and the light utilization efficiency is drastically improved for an entire liquid crystal projector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type color display device using a transmission / scattering type liquid crystal display element and an illuminating device using the same.

[0002]

2. Description of the Related Art White light emitted from a single light source is separated into three colors of R (red), G (green) and B (blue) by a dichroic mirror, and then three lights are provided for each color. 2. Description of the Related Art There is already known a projection type liquid crystal display device in which incident light is incident on a liquid crystal display element, emitted light is color-synthesized by a dichroic mirror, and then projected onto a screen using a single projection optical system.

A comparative example having the basic structure is shown in FIG. The color separation / combination optical system of this comparative example is, for example, "Proceeding of Japan Display 92, 1".
Page 13 ”.

Further, the light source optical system is provided with an elliptic mirror and a light source in the vicinity of the first focal point position, the directivity of the light source light is improved by using a diaphragm, and substantially parallel light is obtained by a condenser lens to transmit and scatter. Japanese Patent Application Laid-Open No. 4-113344 discloses a single-plate type projection display device which is made incident on a liquid crystal display element of a mold and further has a converging lens and a projection lens.

Further, a projection type display device in which a long rod type prism is arranged at the position of the diaphragm is disclosed in JP-A-4-142.
528. In these conventional examples, the light source light emitted from the light source optical system is first converted into substantially parallel light by a condenser lens and then incident on a dichroic mirror.

Next, a comparative example shown in FIG. 8 will be described. In this comparative example, an elliptic mirror 72, a light source 71, a diaphragm 77, a condenser lens 731, and a transmission / scattering type display element 75.
It is composed of R, 75G and 75B and dichroic mirrors 741 and 742 which are color separation / synthesis systems.

Then, the light source 71 is arranged at the position of the first focal point of the elliptical mirror 72, the light from the light source 71 is condensed at the position of the second focal point, and the diaphragm 77 arranged at the position of the second focal point. The light passing through the opening is condensed by the first condensing lens 731, converted into substantially parallel light, and separated into B, G, and R by the dichroic mirror 741 for color separation, and then, corresponding to each color. The non-scattered light of the transmitted light is made incident on the transmission / scattering type display elements 75B, 75G, 75R, and is condensed on the projection lens by the condenser lenses 732B, 732G, 732R provided for each display element, and color combination is performed. The colors are combined by the dichroic mirror 742 for.

However, from the light source optical system to the liquid crystal display element 75
The uniformity of the intensity distribution of the light incident on B, 75G, and 75R and the projected light flux were still insufficient. This is because the light that is blocked by the light source 71 itself and forms an angle of about 10 ° or less with the optical axis at the second focal point is insufficient, and a shadow appears near the center of the transmissive-scattering display element.

When a transmission / scattering type liquid crystal display element is used in a projection type display device, the contrast ratio of the projected image depends on the directivity of the incident light on the liquid crystal display element and the F number of the projection optical system. It is known that the higher the directivity of the incident light on the display element and the larger the F number of the projection optical system, the higher the contrast ratio is achieved. For example,
"Proceeding of Japan Display 9
This is described in "Page 2, 113".

Since the light emitting portion of the lamp used as the light source is not an ideal point light source, in order to efficiently irradiate parallel light with high directivity on the surface of the liquid crystal display element, the light collecting portion having a relatively large focal length f. Requires a lens (mainly
Used as a collimating lens). The light source optical system having such a condenser lens as a constituent element causes an increase in volume, which causes a problem that the entire projection type display device becomes large in size.

[0011]

SUMMARY OF THE INVENTION The present invention is a projection type display device and a lighting device using a transmission / scattering type display element, which further improves the utilization efficiency of light from a light source, and also the contrast ratio and uniformity of a projected image. It is an object of the present invention to provide a small-sized projection type display device. In particular,
Provided is a projection type liquid crystal display device for projecting and displaying a full-color high-density TV image or the like provided with a color separation / synthesis optical system.

[0012]

According to the present invention, a light source optical system for emitting light from a light source, a color separating means for separating the light from the light source into color light, a light collecting means for collecting the color light, and an external signal according to an external signal. Consists of a transmission-scattering type display element that has different light scattering ability and is provided for each color light, and a projection optical system that color-synthesizes the color lights that have passed through the display element to generate color display light and project it onto a screen or the like. In the projection type color display device described above, the light source optical system includes a light source, an elliptic mirror, and a cone-shaped reflector, and the condensing unit is in the optical path after the color separating unit, and Provided is at least one of a light incident side or a light emitting side, and color light in an optical path from a color separation means to a light condensing means is non-parallel light. To do. Here, as will be described later, the non-parallel light means that the light flux of the light source light emitted from the cone-shaped reflector (or the opening of the first diaphragm when additionally provided) has a substantially tapered shape (end spread). ) Is diffused light or divergent light, is incident on the color separation means, and further proceeds to the light collecting means to the display element or the display element to the light collecting means.

More specifically, a light source optical system that emits light from the light source, a color separation means that separates the light from the light source into color light, a light collecting means that collects the color light, and a light scattering ability according to an external signal. A projection type composed of a transmissive-scattering type display element provided for each color light and a projection optical system for color-synthesizing the color lights passing through the display element to generate color display light and projecting the color display light onto a screen or the like. In the color display device, the light source optical system includes a light source 11, an elliptic mirror 12, and a cone-shaped reflector, and the light source 11 and the second elliptic mirror 12 are located near the position of the first focal point of the elliptic mirror 12. The cone-shaped reflectors are arranged in the vicinity of the focal point, and the apex angle α of the reflection surface of the cone-shaped reflector is 165 ° to
177 ° convex cone-shaped reflector 1 or apex angle β is 183 ° to
It is a concave cone-shaped reflector 2 of 195 °, and the condensing means is provided in at least one of the light incident side or the light emitting side of each display element in the optical path after the color separating means, and emits light from the light source 11. The light source light reflected by the elliptical mirror 12, further reflected by the cone-shaped reflector, and emitted from the light source optical system is color-separated into color light by the color separation means, and each color light is transmitted and scattered by the display element, and each color is further separated. A second projection-type color display device is characterized in that the light is condensed by each condensing unit arranged in the optical path for each light, and color combination is performed to form color display light, which is then projected from the projection optical system. provide.

Further, in the above-mentioned first projection type color display device, the light source optical system is provided with a light source, an elliptical mirror, a spherical mirror and a cone-shaped reflector, and the ellipsoidal mirror has a position near the first focal point. A light source, a cone-shaped reflector near the position of the second focal point of the elliptical mirror,
Spherical mirrors each having a curvature center near the position of the first focal point of the elliptical mirror are arranged, and the depth H of the elliptic mirror and the first focal length f1.
And X = H / f1 is 1 to 1.3, and the reflecting surface of the spherical mirror covers the first focal point of the elliptical mirror from the second focal direction side and has an opening on the second focal direction side. A third projection type color display device is provided.

Further, in the projection type color display device according to any one of the above first to third, the light condensing means includes the first light condensing means arranged on the light incident side of the display element and the display element. A fourth projection type color display device is provided, which is provided with a second condensing unit arranged on the light emitting side. In this case, the second condensing unit functions to substantially condense the transmitted light from the display element at the pupil position of the projection lens of the projection optical system.

Further, in the projection type color display device according to any one of the above first to third aspects, the light condensing means is arranged on the light incident side of the display element, and a fifth projection type color display device is provided. A display device is provided.

In each of the above projection type color display devices,
The condensing unit functions to condense the color light obtained by color-separating the light source light onto the display surface of the display element or the projection optical system. Also,
Specifically, a dichroic mirror is used as the color separating means and the color synthesizing means, and a liquid crystal display element is used as the display element. Further, for color combination, a plurality of projection optical systems may be provided for each color light instead of using a dichroic mirror, and colors may be combined on a screen or the like to obtain a projected image. An ordinary condenser lens is used as the condenser means, and a convex lens (biconvex lens, plano-convex lens) or the like is used as the shape thereof.

Further, in the projection type color display device according to any one of the first to fifth aspects, a first diaphragm is provided at a position between the reflector and the color separation means. 6 projection type color display device is provided.

In the projection color display device according to any one of the first to sixth aspects, the image of the cone-shaped reflector or the first diaphragm is formed at a position where the image is formed by the condensing means. A seventh projection type color display device is provided, in which a second diaphragm having an opening of substantially the same shape is arranged.

In the projection color display device according to any one of the first to seventh aspects, a liquid crystal display element is used as a display element, and a nematic liquid crystal having a positive dielectric anisotropy is provided between the substrates with electrodes. Is a liquid crystal display device having a liquid crystal solidified substance complex dispersedly held in a solidified substance matrix and having the refractive index of the solidified substance matrix matched with the ordinary refractive index (n ₀ ) of the liquid crystal used. Characteristic eighth
The present invention provides a projection type color display device. Here, specifically, the liquid crystal solidified composite refers to a structure in which a nematic liquid crystal is dispersed and held in a polymer, and liquid crystal droplets formed in a capsule shape are substantially particulate (spherical or elliptical, or It is preferable that a part of the particles are connected to each other) because an optically high scattering power can be obtained.

Further, there is provided an illuminating device characterized by using any one of the above-mentioned projection type color display devices.

The present invention will be outlined with reference to FIG.
The light source optical system of the present invention includes an elliptic mirror 12, a light source 11, and a convex cone-shaped reflector 1 or a concave cone-shaped reflector 2 described later. The convex cone-shaped reflector 1 has an apex angle α of 150 in its cross section.
A convex shape of 0 ° to 177 °, preferably 165 ° to 177 °,
In the case of the concave cone-shaped reflector 2, the apex angle β is 183 ° to 210.
And preferably 183 ° to 195 °. That is, it forms a convex or concave reflector for the incident light. What actually functions is a conical reflecting surface having a volume in a three-dimensional space. In the present invention, the light source optical system (from the light source to the first diaphragm or the conical reflector)
In addition, since the condenser lenses that play the role are arranged dispersedly in the optical path of each color light without providing a condenser lens with a large power, the shape of a cone is considered in consideration of the focal length of the condenser lens. The apex angle of the reflector will be more specified (the apex angle range is narrower, but also depending on the overall size of the projection display device).

Further, it is preferable that the apex angle α or the apex angle β can be changed. In addition, the projected image is often non-square in general, and it is preferable that the apex angle α or the apex angle β be different in at least two cross sections including the optical axis. Further, the conical shape is a shape of a truncated cone, a truncated pyramid, a pyramid, or the like, and two types of irregularities can be used for each. Further, it may be a three-dimensional curved body having an apex angle close to the above angle.

The convex or concave reflector is an elliptical mirror 12.
It is most efficient to place it at the second focus position of
In the case of a convex cone-shaped reflector, its apex is on the ellipsoidal mirror side from the second focus position, and in the case of a concave cone-shaped reflector, its apex is on the opposite side of the ellipsoidal mirror from the second focus position. It is preferable to be arranged within a distance of about the light emission length or less. Strictly speaking, the optimum position is determined by the light distribution of the light source 11 and the positional relationship between the first focus of the elliptic mirror and the light emitting portion of the light source.

At this time, the light that has reached other than the effective reflection surface of the convex or concave cone-shaped reflector is the condenser lens 13.
It is preferable not to reach B, 13G and 13R. In some cases, the first diaphragm 17 may be provided between the conical reflector and the condenser lens near the second focal position of the elliptical mirror 12.

With this arrangement, the finite-length light-emitting portion and the elliptical mirror can remove the light component that is not condensed near the second focal point and make the light beams uniform, and reach the screen when the transmission / scattering type display element is in the scattering state. It is possible to reduce unnecessary light and improve the contrast ratio.

In particular, it is more effective to provide means for removing scattered light, specifically, the second diaphragm 18 between the transmission / scattering type display element and the screen.

Further, since the condenser lens is provided on at least one of the light incident side and the light emitting side of each of the three liquid crystal display elements, the light source light incident on the color separation means is used by using a single condenser lens. Compared to the above-mentioned conventional example of parallel light,
Since the light source optical system is downsized and a condenser lens having a relatively long focal length is used, it is easy to obtain parallel light with high directivity as a result.

2 and 3 show ray trajectories in the case of the convex cone-shaped reflector 1 and the concave cone-shaped reflector 2. It can be seen that the outgoing light from the elliptical mirror is deflected by the reflecting surface of the cone-shaped reflector to generate an azimuth light component near the optical axis and the luminous flux density increases.

A single elliptic mirror 1 as a condenser mirror of the light source optical system.
As compared with the case where 2 is used, by using a compound condensing mirror in which an elliptic mirror 12A and a spherical mirror 12B are combined as shown in FIG. 4, light having uniform directivity is efficiently condensed (for example, in FIG. Three condensing lenses 131B and 131
G, 131R, which is a condenser lens on which color light is first incident) can be condensed in the effective surface.

At this time, the elliptic mirror 12A has a depth H of its reflecting surface shallower than that shown in FIGS. 2 and 3, and the ratio X = H / f1 to the first focal length f1 is 1 to 1. 1.3
It is preferable to set the degree.

The spherical mirror 12B is the first of the elliptical mirrors 12A.
The center of curvature is in the vicinity of the focal point and its reflecting surface is an elliptical mirror 1.
2A covers the second focus direction side from the first focus of 2A
It is configured to have an opening on the focal direction side. Even when the compound condenser mirror is used, the arrangement configuration relationship with the cone-shaped reflector is the same as in FIGS. 2 and 3.

[0033]

In the projection type color display device of the present invention, the dispersion angle φ representing the directivity of the incident light emitted from the light source optical system and incident on the liquid crystal display element is the effective reflection of the cone-shaped reflector of the light source optical system. The diameter D of the light exit surface defined by the surface or the first diaphragm and the distance L between the light exit surface and the condensing lens or the distance to the liquid crystal display element, whichever is shorter, is used for approximation. It is described as the following Equation 1.

[0034]

## EQU1 ## tan (φ) = D / L

Φ, D, and L are shown in FIGS. 5 to 7 for various configurations described later. At this time, the light emitting surface of the light source optical system does not necessarily have to be circular and may have a shape such as a rectangle or an ellipse, but in that case, the diameter D corresponds to the average diameter.

Therefore, the dispersion angle φ of the parallel light incident on the liquid crystal display element becomes smaller as the diameter D of the light emitting surface is smaller or the distance L is larger, and the light has high directivity. However, in general, the smaller the diameter D of the light exit surface,
The ratio of the emitted light from the light source that can emit the inner diameter D decreases.
Further, as the distance L increases, the luminous flux density decreases, so that the luminous flux incident on the liquid crystal display element having the same display area decreases.

Therefore, in order to efficiently generate light with high directivity and to form a projection image having a uniform intensity distribution, the shape of the elliptical mirror 12 and the conical reflector which are the constituent elements of the light source optical system. And the display area of the liquid crystal display element (15B, 15G, 15R in FIG. 1 in the case of the three-element configuration) and the condenser lens (the combination of the above-mentioned first condenser lens and second condenser lens). There is a predetermined relationship with the focal length (including when configured).

The divergence angle φ of the incident light on the liquid crystal display element is determined to an appropriate angle depending on the required contrast ratio of the screen projection image and the scattering ability of the transmission / scattering type liquid crystal display element.

10 ° when the contrast ratio is 50 or more
The following dispersion angle φ, and D and L defined by the equation 1 so that the dispersion angle φ is 7 ° or less when the contrast ratio is 100 or more.
Is preferably selected.

Further, in order not to increase the size of the light source optical system, the ratio f between the second focal length f2 of the elliptic mirror and the first focal length f1.
It is preferable that _X = f2 / f1 be 10 or less. Further, in the case where the distance between the light source optical system and the liquid crystal display element is long, the numerical aperture (lens diameter / focal length) of the condenser lens is a small value of 0.3 or less. In order to efficiently emit light into the effective surface of the lens,
It is preferable that f _X = f2 / f1 of the elliptical mirror is 4 or more.

Under such a premise, according to the present invention,
The non-uniformity of the in-plane light intensity distribution of the transmission-scattering type display element 15 due to the lack of a light component having a small angle with the optical axis at the second focal position when the elliptical mirror 12 is used is caused by the light source 1.
1 and the elliptic mirror 12 have an apex angle α of 165 ° to
177 ° convex cone-shaped reflector 1 or apex angle β is 183 ° to
It is improved and homogenized by using a 195 ° concave cone-shaped reflector 2. In terms of light utilization efficiency and brightness distribution on the projection screen, the apex angle α is more preferably 1
72 ° to 176 °, and the apex angle β is 184 ° to 188 °.

A light source optical system comprising an elliptic mirror 12, a light source 11, and a convex or concave cone-shaped reflector, and B and G
A condensing lens arranged for each liquid crystal display element corresponding to R color light is used. Therefore, a large amount of light from the light source 11 can be used even by the small elliptic mirror 12, and the light source optical system can be downsized, so that the volume of the projection display apparatus can be reduced.

In the present invention, three types of configurations shown in FIGS. 5 to 7 can be considered for the arrangement relationship between the condenser lens and the liquid crystal display element. The configuration will be described below.

In FIG. 5, plano-convex lenses are arranged on both the light input and output sides of the display element 15 so that the light incident on the display element 15 becomes substantially parallel light. Since the condensing optical system located in front of the display element 15 (on the light source side) does not directly contribute to the formation of the projected image, it is generally called a condensing lens (condenser lens) in many cases. A major role is to collect the light supplied from the light source side and transmit it to the display element 15.

Further, when it is used like the condenser lens 131 of FIG. 5, it can be called a collimating lens.
However, the term “collimating lens” does not mean that perfect collimated light is obtained, but that light incident on the display element 15 is substantially parallel.

In the example of FIG. 5, a second condenser lens is provided after the display element 15. The condensing optical system provided after the display element (on the emission side) affects the resolution of the projected image. In that sense, it may be said that it is a part of the projection optical system. Generally, it is often called a field lens. However, a lens having a large radius of curvature is rarely used, and a substantial projection function depends on a projection optical system provided in a subsequent stage.

In FIG. 5, the luminous flux (the diameter of the opening is D) defined by the first diaphragm 17 provided on the light source side is condensed by the condenser lens 131 to be substantially collimated and displayed. It is incident on the element 15. Then, the display light (modulated color light) modulated by the transmission and scattering function of the display element 15 is condensed by the condenser lens (field lens) 132. By arranging the second diaphragm 18 at a position conjugate with the first diaphragm 17,
An image of the opening of the first diaphragm 17 will be generated at the position of the second diaphragm. In this case, scattered light is removed, which is preferable. In FIG. 5, the condenser lens 131 and the condenser lens 1
A condenser lens 1 that can function as a condenser by combining 32
Call 3.

In FIG. 6, the condenser lens 13 is arranged on the light incident side of the display element 15 and on the light emitting side of the display element 15 in FIG. In FIG. 6, the light (color light) supplied from the light source side is converged and converted by the condenser lens 13 arranged in front of the display element 15, sent to the display element 15, and further, the aperture of the first diaphragm 17 is changed. The image is arranged so that it is generated at the opening of the second diaphragm 18. In FIG. 7, conversely, the condenser lens 13 is arranged after the display element 15.

Any arrangement is possible, and when the electro-optical characteristics of the liquid crystal display element have angle dependence, the configuration of FIG. 5 in which incident light is parallel light is preferable, but the total number of condenser lenses is six. You need one.

On the other hand, in the configuration of FIG. 6, the condensing lens can be regarded as a part of the light source optical system and can be considered to be separated from the projection optical system almost. Therefore, compared with the configuration of FIG. Pixel adjustment of the element is facilitated and the number of condenser lenses is not increased as compared with the conventional optical system.

Further, a first diaphragm (reference numeral 17 in FIGS. 5 to 7) is installed near the second focal point position of the elliptic mirror and between the reflector and the condenser lens (or color separation means). This first
The diaphragm and the second diaphragm (reference numeral 18 in FIGS. 5 to 7) provided as means for removing scattered light can be made variable. More preferably, the two diaphragms are linked.

In this case, the following advantages can be obtained. When trying to obtain a projected image, when the surroundings are dark, the influence of light from the surroundings on the screen is small, so dark points in the projected image by the projection display device can also be identified. At this time, it is possible to adjust the contrast ratio to be high even if the amount of light is reduced by narrowing down the two diaphragms, and a display image with a high contrast ratio and easy-to-see brightness can be obtained.

On the contrary, when the surroundings are bright, the light from the surroundings is reflected on the screen, and the dark portion of the projection image by the projection type display device looks bright to some extent.
At this time, the two diaphragms are opened to increase the amount of projected light and brighten the screen, so that the contrast ratio can be increased and it becomes easier to see.

The second diaphragm has a light emitting surface shape of the light source optical system defined by the conical reflector or the first diaphragm,
It is preferably installed at a position where an image is formed by the second condenser lenses 132B, 132G, and 132R and has the same shape as the image of the light emitting surface shape in terms of light utilization efficiency and scattered light removal efficiency.

Further, in order not to increase the aperture of the projection lens, it is preferable to dispose this second diaphragm at the pupil position of the projection lens.

[0056]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 FIG. 1 shows a projection type color display device 10. In the present embodiment, the light source 11 is arranged at the first focal point of the elliptic mirror 12, and the light (source light emission) emitted from the light source 11 is reflected by the elliptic mirror 12 to be a reflector provided substantially at the second focal point position. It is incident on the reflecting surface of (convex cone-shaped reflector 1),
As the light is reflected by the reflecting surface, the azimuth distribution of the luminous flux after reflection is changed. Further, in the present embodiment, a first diaphragm is provided in the optical path between the reflector and the first condenser lens in the vicinity of the second focal position of the elliptical mirror, and the opening of the first diaphragm 17 is provided. It passes through and is emitted as light source light. This first diaphragm 1
7 may be provided if necessary. The effective reflection surface of the reflector itself can function as a diaphragm.

Then, the process further proceeds, and after being color-separated into three colors of B, G, and R by two kinds of dichroic mirrors (and a reflection mirror), the first condenser lenses 131B and 1B are provided.
31G and 131R (the shape is a plano-convex lens) respectively enter and are made into substantially parallel light.

Transmission / scattering type liquid crystal display elements 15B, 15
Non-scattered light that has passed through G and 15R (modulated transmitted light)
Is condensed on the projection optical system 19 by the second condenser lenses 132B, 132G, 132R, and is projected on a screen (not shown) by the projection lens. On the other hand, the scattered light is removed by the second diaphragm 18 and is not projected on the screen.

The light source 11 used here is a discharge light emission type metal halide lamp, a xenon lamp, a filament light emission type halogen lamp or the like, but in general, all of them are electrodes of the light source section, tube glass, and heat insulating film. Since there is a light-shielding portion such as a filament, the emitted light in the vicinity of the azimuth angle parallel to the optical axis emitted from the light source is small, and the reflected light from the elliptical mirror 12 has a small amount of the emitted light component in the vicinity of the parallel azimuth angle to the optical axis. .

As a result, in the case of the comparative example of FIG. 8 in which the reflector (convex cone-shaped reflector 1) is not used, there is a shortage of light whose angle with the optical axis at the second focus is about 10 ° or less, A shadow was formed in the vicinity of the center of the transmission / scattering type display element 15. However, when a cone-shaped reflector is used as in the present embodiment, the luminous flux azimuth angle changes due to reflection on the reflecting surface, and the optical axis is different from the optical axis. The angle formed by is about 10
By compensating for the lack of light of less than °, the non-uniformity of the light intensity near the center of the transmission-scattering type display element was corrected, and the light was almost made uniform.

Each part constituting this embodiment will be described. In this embodiment, the display portion of the active-matrix-driven transmission / scattering type liquid crystal display element 15 has a diagonal of 3 inches, the aperture ratio of the pixel is 40%, and the liquid crystal display elements 15B and 15G.
The maximum transmittance of 15R is 30%.

As the light source optical system, a light source 11 (metal halide lamp of light emission arc length 4 mm, 150 W), elliptical mirror 12 (first focal length f1 = 14 mm, second focal length f)
2 = 134 mm, total depth H = 45 mm, convex cone-shaped reflector 1 (vertical angle 173 °, bottom cross-sectional diameter 40 mm, height 8)
mm, but the height of the inclined surface of the cone-shaped reflector is 1.22
mm) is used.

As the condenser lens optical system, first condenser lenses 131B, 131G, 131R (focal length 225 mm
Plano-convex lens) and the second condenser lenses 132B, 132
G, 132R (plano-convex lens with a focal length of 225 mm) is used. A first iris diaphragm 17 having a variable aperture diameter is provided in the optical path between the convex cone-shaped reflector 1 and the first condenser lens in the vicinity of the second focal position of the elliptic mirror.

The liquid crystal display element used was one in which a nematic liquid crystal having positive dielectric anisotropy was encapsulated. Of the light transmitted through the transmission / scattering type display elements 15B, 15G, and 15R, only the light that has passed through the second diaphragm 18 is imaged as a liquid crystal display image on the screen through the projection optical system 19.

At this time, the light emitting surface of the light source optical system defined by the cone-shaped reflector or the first diaphragm 17 is the second
The second iris diaphragm 18 having a variable aperture diameter is arranged at the pupil position of the projection lens, which is the position where images are formed by the condenser lenses 132B, 132G, and 132R.

As a result, according to the present invention, even when a small light source optical system is used, the illuminance distribution of the finally obtained projection image is made uniform, and the luminous flux, which is the integrated light quantity within the screen surface, is made to have a contrast ratio. Can be increased without deteriorating.

In particular, the remarkable shortage of light amount near the center of the screen, which occurs when the convex or concave cone-shaped reflector of the present invention is not used, is improved, the maximum illuminance is obtained at the center of the screen, and a large area display screen is obtained. A bright and easy-to-see display is obtained.

In the case of the cone-shaped reflector, any material may be used as long as it can provide an optical plane. A reflective prism is formed by forming a metal reflective layer or a dielectric multilayer reflective layer on the side surface of a conical prism having an optical plane. A cold mirror that reflects light in the required wavelength range on the optically polished optical glass prism surface and transmits / absorbs unnecessary light, such as a cold mirror that reflects visible light and transmits heat rays, an optical interference dielectric multilayer film layer ( It is preferable to form a dielectric multilayer film mirror).

In this embodiment, instead of the dichroic mirror having an incident angle of 45 ° which is usually used as a color separation / combination system, the incident angle becomes about 30 ° in order to improve the light utilization efficiency without reducing the color purity. Although the dichroic mirrors are arranged as described above, the arrangement of the dichroic mirrors with the incident angle of 45 ° is not a problem as in the conventional case.

(Example 2) In the light source optical system of Example 1, instead of a single elliptic mirror, a compound condenser mirror in which an elliptic mirror and a spherical mirror were combined was used. Its configuration is an elliptical mirror 12A.
(First focal length f1 = 22 mm, second focal length f2 = 1
05 mm, total depth H = 25 mm, spherical mirror 12B (radius of curvature R = 45 mm, aperture diameter (large) = 99 mm, aperture diameter (small) = 60 mm), convex cone-shaped reflector 1 (vertical angle 173)
°, the bottom cross-sectional diameter is 40 mm, the height is 8 mm, but the height of the inclined surface of the conical reflector is 1.22 mm).

Here, as shown in FIG. 4, the spherical mirror 1
The center of curvature of 2B is located near the first focal point of the elliptical mirror 12A, that is, substantially at the light emitting portion of the light source 11. In addition, the spherical mirror and the elliptical mirror have the same axis of rotational symmetry, and the opening of the spherical mirror (large)
Is on the first focal point side of the elliptical mirror and the opening (small) is on the second side of the elliptic mirror.
Place it so that it is on the focal side. Further, as in the first embodiment, the first iris diaphragm 17 having a variable aperture diameter is provided between the reflector and the condenser lens in the vicinity of the second focal position of the elliptic mirror. Other configurations are the same as those in the first embodiment.

By using such a light source optical system, it is possible to realize a projection type display device having a higher light utilization efficiency than that of the first embodiment, that is, a large screen light flux.

Further, in the projection type color display device of the present invention, a transmission / scattering type liquid crystal display device is used as an illuminating device with a fixed pattern or a simple matrix display, so that bright full color illumination with high color purity is possible. In addition, the illumination color and brightness can be adjusted at high speed.

[0075]

In the projection type color display device of the present invention, the light emitted from the light source is condensed using the elliptical mirror 12, so that the condensing efficiency is high and bright display is possible. In addition, the light-collecting efficiency is dramatically improved by the configuration of the composite light-collecting mirror in which the elliptic mirror and the spherical mirror are combined.

Further, a convex or concave cone-shaped reflector having a specific shape is provided at the second focal position of the elliptic mirror, and further the first
The iris 17 is provided to remove the divergent light. Therefore, since the light source has a finite length, it is possible to remove the light reflected by the elliptical mirror 12 and not directed to the display element without passing through the second focal point position. The contrast ratio of can be improved.

Further, since the apex angle α is 165 ° to 177 ° and the apex angle β is 183 ° to 195 ° in this reflector, the first elliptic mirror generated when a light source having a light shielding portion and an elliptic mirror is used. The non-uniformity of the in-plane light intensity distribution of the transmissive-scattering type liquid crystal display element 15 due to the lack of the light component parallel to the optical axis at the two focal points is improved, and a large amount of light of the projected image is taken, especially in the central portion. It is possible to obtain a bright, high-contrast projection type color display device having excellent illuminance uniformity. The light source light has a condensing angle of 2 to 10 °, preferably 2 to 6 °, and a bright projection image with high light utilization efficiency is generated.

Further, by condensing the condensing lenses having a long focal length in the liquid crystal display elements corresponding to respective colors, it is possible to reduce the size of the projection type color display device without increasing the volume. In addition, it is possible to generate incident light to the liquid crystal display element, which is extremely bright and has high directivity.

In addition to the above, the present invention can be applied in various ways within a range that does not impair the effects of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a projection type color display device of the present invention.

FIG. 2 is an enlarged view of a light source optical system using the convex cone-shaped reflector of the present invention.

FIG. 3 is an enlarged view of a light source optical system using the concave cone-shaped reflector of the present invention.

FIG. 4 is an enlarged view of a light source optical system using a complex condenser mirror and a convex cone-shaped reflector of the present invention.

FIG. 5 is a block diagram showing a positional relationship between the liquid crystal display element of the present invention and a condenser lens (first condenser lens and second condenser lens).

FIG. 6 is a block diagram showing an arrangement relationship between a liquid crystal display element of the present invention and a condenser lens (front lens).

FIG. 7 is a block diagram showing a positional relationship between the liquid crystal display element of the present invention and a condenser lens (rear lens).

FIG. 8 is a block diagram showing a comparative example.

[Explanation of symbols]

1: Convex Conical Reflector 2: Concave Conical Reflector 10: Projection Color Liquid Crystal Display Device 11: Light Source 12, 12A: Elliptical Mirror 12B: Spherical Mirror 131R, 131G, 131B: Condensing Lens 132R, 132G, 132B : Condensing lens (field lens) 15R, 15G, 15B: Liquid crystal display element 17: First diaphragm 18: Second diaphragm 19: Projection optical system 141: Color separating means 142: Color combining means

Front page continuation (72) Inventor Nariyuki Serizawa 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Asahi Glass Co., Ltd. In the laboratory

Claims (9)

[Claims] 1. A light source optical system that emits light from a light source, a color separation unit that color-separates the light from the light source, a condensing unit that condenses the colored light, and a light scattering ability that changes according to an external signal. A projection type color display device comprising a transmission / scattering type display element provided for each of the display elements and a projection optical system for color-synthesizing the color lights passing through the display element and projecting the color display light on a screen or the like. The light source optical system includes a light source, an elliptic mirror, and a cone-shaped reflector, and the condensing unit is in the optical path after the color separating unit and is at least one of the light incident side or the light emitting side of each display element. The projection type color display device is characterized in that the color light in the optical path from the color separating means to the light collecting means is non-parallel light. 2. The projection type color display device according to claim 1, wherein the light source optical system includes a light source, an elliptical mirror, a spherical mirror and a cone-shaped reflector, and the light source is located near the position of the first focal point of the elliptic mirror. , A cone-shaped reflector near the position of the second focal point of the elliptic mirror, and a spherical mirror having a curvature center near the position of the first focal point of the elliptic mirror, respectively, and the depth H of the elliptic mirror and the first focal length f1 are set. The ratio of
X = H / f1 is set to 1 to 1.3, and the reflecting surface of the spherical mirror covers the second focus direction side from the first focus of the elliptical mirror and the second focus.
A projection type color display device having an opening on the focal direction side. 3. The projection type color display device according to claim 1 or 2, wherein the first condensing means is disposed on the light incident side of the display element and the second condenser is disposed on the light emitting side of the display element. A projection type color display device comprising: a light unit. 4. The projection type color display device according to claim 1, wherein the light condensing means is arranged on the light incident side of the display element. 5. The projection type color display device according to claim 1, wherein a first diaphragm is provided between the cone-shaped reflector and the color separation means. Projection type color display device. 6. The projection type color display device according to claim 1, wherein an image of the cone-shaped reflector or the first diaphragm is formed substantially at the position where the image is formed by the light converging means. A projection type color display device in which a second diaphragm having an opening of the same shape is arranged. 7. The projection type color display device according to claim 1, wherein a liquid crystal display element is used as a display element, and a nematic liquid crystal having a positive dielectric anisotropy is provided between the substrates with electrodes. Is a liquid crystal display device having a liquid crystal solidified substance complex dispersedly held in a solidified substance matrix and having the refractive index of the solidified substance matrix matched with the ordinary refractive index (n ₀ ) of the liquid crystal used. Characteristic projection type color display device. 8. A light source optical system for emitting a light source light, a color separation means for color-separating the light source light into color light, a light condensing means for condensing the color light, and a light scattering ability which changes according to an external signal. It is composed of a transmission-scattering type display element provided for each color, a color separation means for color-synthesizing the color lights that have passed through the display element, and a projection optical system for projecting the color-synthesized color display light onto a screen or the like. A projection-type color display device, wherein a light source optical system includes a light source, an elliptic mirror, and a conical reflector, and a light condensing unit is in an optical path after the color separating unit, and light is incident on each display element. A projection type color display device, characterized in that the color light in the optical path from the color separation means to the light incidence side condensing means is provided as non-parallel light, respectively provided on the light emitting side and the light emitting side. 9. An illuminating device comprising the projection type color display device according to claim 1.