JPH08313860A - Projection type display device - Google Patents

Abstract

PURPOSE: To obtain a projection picture having a high picture quality with a high light utilizing efficiency while suppressing the increasing of cost. CONSTITUTION: A light source 1 makes the illuminating light L1 having about an ellipse-shaped image generate by the arc discharge between paired electrodes. The illuminating light L1 is made incident on the reflection type liquid crystal panel 5 consisting of, for example, PDLC picture elements through a condenser lens 2, a reflection mirror 3 and an objective lens 4. The light reflected on the reflection type liquid crystal panel 5 becomes a projection light L2 to be projected on a screen through the objective lens 4, the aperture 6a of a diaphragm 6 and a projection lens 7. At this time, the illuminating light L1 and the projection light L2 are separated in the direction orthogonal to the longitudinal direction of the image by the light source 1 (in the up-and-down direction of the figure). Images of the illuminating light L1 and the projection light L2 in the reflection mirror 3 and the diaphragm 6 each have longitudinal direction parallel with each other and both images are designed so that they exist within the effective diameter of the lens. Moreover, the aperture 6a of the diaphragm 6 is formed to a slot shape extending in the longitudinal direction of the image by the light source (in the direction orthogonal to the plane of the figure).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device using a reflection type image element.

[0002]

2. Description of the Related Art FIG. 11 shows a general structure of a projection type liquid crystal display device using a reflection type liquid crystal panel. In FIG. 11, the light source 41 has a pair of electrodes 41a and 41b, and a space between the electrodes 41aa and 41b is a light emitting portion. Illumination light emitted from the light source 41 passes through a condenser lens 42, a reflection mirror 43, and an objective lens 44, for example, PDLC.
(Polymer dispersed liquid crystal) Liquid crystal panel 45 including image element
Is incident on. Then, the projection light reflected from the liquid crystal panel 45 is projected onto a screen (not shown) via the objective lens 44, the aperture 46a of the diaphragm 46, and the projection lens 47.

In this case, the illumination light and the projection light are separated at a minute angle so as to be symmetrical with respect to the central axis (optical axis) of the objective lens 44, and in general, the illumination light and the projection light both have an image. It is designed to fit within the effective lens diameter. The lens effective diameter corresponds to the diameter of the exit pupil of the objective lens 44 or the diameter of the entrance pupil of the projection lens 47 capable of maintaining good image quality, and the illumination light and the projection light are included in this lens effective diameter. A high-quality projected image can be obtained by connecting the images.

[0004]

However, the above-mentioned conventional projection type liquid crystal display device has the following problems. That is, since the light source 41 generates an arc between the pair of electrodes 41a and 41b, the light image thereof has a substantially elliptical shape extending in the direction connecting the electrodes 41a and 41b. In this case, as shown in FIG.
1 from the side of the objective lens 44, the reflection mirror 43 and the diaphragm 46.
(As viewed), the reflection mirror 43 and the diaphragm 46
The opening 6a of the optical disk has, for example, a circular shape, and in order to put the light image in the lens effective diameter (diameter indicated by a chain double-dashed line), the light image (I
The size of () will be limited. as a result,
This causes a problem that it is difficult to obtain a bright image.

Further, in FIG. 11, it may be considered that the projection lens 47 may be moved to the upper part of the figure, but as the optical axes of the objective lens 44 and the projection lens 47 are displaced, it becomes difficult to secure the image forming characteristics. However, there arises a problem that it is difficult to obtain a high quality projected image.

In response to the demand for brightening the projected image, for example, when the focal length of the condenser lens 42 is shortened to increase the optical image, the reflection mirror 43 and the diaphragm 4 are used.
The image (image of illumination light, image of projection light) at 6 becomes large, and the effective diameter is large (that is, generally called “bright”, “low F No.” projection lens 47 (or objective lens 44). As a result, there arises a problem that the cost of the optical system increases.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a projected image with high light utilization efficiency and high image quality while suppressing cost increase. It is to provide a projection display device.

[0008]

In order to achieve the above object, a first aspect of the present invention is directed to a light source having a light emitting portion having anisotropy in shape, and for converging illumination light from the light source. 1 lens, a reflection mirror that reflects the illumination light condensed by the first lens, a reflection type image element that reflects the illumination light from the reflection mirror as projection light, and a reflection type image element In a projection-type display device including a second lens that allows incident light and reflected light to pass therethrough, and a diaphragm that is disposed adjacent to the reflection mirror, the illumination light and the projection light are lengthened by the light source. Separated in a direction orthogonal to the direction, and
The gist is that the aperture of the diaphragm is formed in a long hole shape extending in the longitudinal direction of the image formed by the light source. 3 Claim 2
In the invention described in Item 1, in the invention described in Item 1, the shape of the aperture of the diaphragm is substantially matched with the image by the light source.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the first lens is composed of two or more lens groups including at least one positive meniscus lens. are doing.

[0010]

According to the first aspect of the invention, the light source has an anisotropic shape in the light emitting portion, and generates illumination light by arc discharge between a pair of electrodes, for example. The illumination light is condensed by the first lens, reflected by the reflection mirror, passes through the second lens, and is incident on the reflective image element. Then, the light reflected by the reflective image element passes through the second lens again and is extracted as projection light.
After that, the projection light passes through the aperture of the diaphragm and then is projected onto, for example, a screen to display a projection image.

In such a case, the illumination light and the projection light are separated in the direction orthogonal to the longitudinal direction of the image by the light source, and the images of the illumination light and the projection light in the openings of the reflection mirror and the diaphragm are parallel in the longitudinal direction. Become. Therefore, the size of both images in the direction orthogonal to the longitudinal direction becomes small, and when the illumination light and the projection light are separated within the effective diameter of the lens, the image of the light can be made large. As a result, a projected image with high light utilization efficiency and high image quality can be obtained.

Further, since the aperture of the diaphragm is formed in a long hole shape extending in the longitudinal direction of the image by the light source, unnecessary light (for example, scattered light in the PDLC image element) can be efficiently removed, and the projected image It is possible to improve the contrast.

When the shape of the aperture of the diaphragm is matched with the image of the light source as described in claim 2, the portion of the aperture of the diaphragm which does not match the image of the light source is reduced,
The unnecessary light is more reliably removed without lowering the brightness. Even when the projection lens that makes the projection light that has passed through the diaphragm incident is a constituent element, the shape of the image by the light source matches the shape of the aperture of the diaphragm, and unnecessary light can be removed in the same manner as above. More surely done.

As described in claim 3, at least 1
If the first lens is composed of two or more lens groups including one positive meniscus lens, the focal length of the first lens can be shortened and a brighter projected image can be obtained. In other words, the improvement of the light-collecting efficiency by shortening the focal length of the single lens is limited due to the aberration and the reflection loss of the lens surface, but the problem is solved by the above configuration.

[0015]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a single reflection type liquid crystal panel is used to form a single-plate projection type liquid crystal display device, and the reflection type liquid crystal panel is composed of PDLC image elements. In addition, this PDLC image element
It is generally known that the polarizing plate, which was indispensable for the TN liquid crystal, can be eliminated, so that there is no loss due to light absorption of the polarizing plate and the brightness can be doubled or more.

FIG. 1 shows the configuration of a projection type liquid crystal display device in this embodiment. In the optical system of FIG. 1, the light source 1 is composed of, for example, a metal halide lamp, and the outline of the light (hereinafter, referred to as a light source image) is generally an aspect ratio = 1: 1.
It becomes a substantially elliptical shape of 1.5 to 1: 5. The structure of the light source 1 is shown in FIG.
Will be explained. FIG. 3A is a front view of the light source 1 viewed from the direction A in FIG. 1, and FIG. 3B is an enlarged view of a light emitting unit in the light source 1.

In FIG. 3A, the glass tube 11 is held by left and right holding portions 12a and 12b, and inside the glass tube 11, electrodes 13a and 13b extending from the both holding portions 12a and 12b to the center are provided. Is provided. The light emitting portion 14 is between the two electrodes 13a and 13b, and the arc generated in the light emitting portion 14 has an arc length (distance between the electrodes 13a and 13b) and an arc diameter (arc) shown in FIG. 3B. Arc diameter in the direction orthogonal to the longitudinal direction). The concrete numerical values in this embodiment are as follows: arc length≈2.5
mm, arc diameter ≈ 0.75 mm, and the light source 1 produces a light source image with an aspect ratio ≈ 1: 3. That is, the light emitting unit 14 has anisotropy.

Illumination light L1 emitted from the light source 1 in FIG. 1 is divided into first and second condenser lenses 2a and 2b.
It is condensed on the reflection mirror 3 via the condenser lens (first lens) 2 made of. Further, the illumination light L1 is reflected by the reflection mirror 3, and the objective lens (second lens) 4
After being converted into parallel light, the light is incident on the reflective liquid crystal panel 5.

After that, the illumination light L1 is reflected by the reflection type liquid crystal panel 5.
And is again reflected by the objective lens 4 as projection light L2. At this time, the illumination light L1 and the projection light L2 are separated at a minute angle so as to be symmetrical with respect to the central axis of the objective lens 4, and the projection light L2 is focused at a position slightly above the reflection mirror 3. A diaphragm 6 having an opening 6a of a predetermined shape is arranged at the position where the projection light L2 is focused, and the projection light L2 that has passed through the opening 6a of the diaphragm 6 passes through the projection lens 7 and is displayed on a screen (not shown). Is projected.

That is, the reflection type liquid crystal panel 5 using the PDLC image element emits non-scattered light and scattered light, but by providing the diaphragm 6, only the non-scattered light is projected onto the projection lens 7.
It is designed to be incident on. Since the light source image has a substantially elliptical shape as described above, the illumination light L1 and the projection light L2 have a substantially elliptical image in the vicinity of the diaphragm 6 whose longitudinal direction is the direction orthogonal to the paper surface.

FIG. 2 is an enlarged perspective view showing the reflection mirror 3 and the diaphragm 6. The reflection mirror 3 and the diaphragm 6 are provided adjacent to each other, and the shape of the opening 6a of the diaphragm 6 is a horizontally long rectangular shape. The shape of the reflection mirror 3 viewed from the objective lens 4 side is also a horizontally long rectangular shape. The longitudinal direction of the reflecting mirror 3 and the longitudinal direction of the opening 6a of the diaphragm 6 are parallel to each other, and these longitudinal directions are the illumination light L1.
And the longitudinal direction of the image of the projection light L2.

FIG. 4 is a view of the reflecting mirror 3 and the diaphragm 6 viewed from the side of the objective lens 4 in FIG. 1. For the sake of convenience, FIG. 4 is a front view of the reflecting mirror 3 and the diaphragm 6 and a sectional view of a light source image. And are shown separately in FIGS. 4 (a) and 4 (b). As shown in FIG. 4A, both the reflection mirror 3 and the aperture 6a of the diaphragm 6 are arranged so as to enter the lens effective diameter (indicated by a chain double-dashed line). Further, as shown in FIG. 4B, the illumination light L1 (I1 in the drawing) on the reflection mirror 3 and the projection light L2 (I2 in the drawing) passing through the diaphragm 6 both enter within the effective diameter of the lens. Is designed to be. The lens effective diameter corresponds to the diameter of the entrance pupil of the projection lens 7 that can ensure good image quality, and this is determined by the performance of the lens itself.

In short, paying attention to the fact that the shape of the light source image (the image of the illumination light L1 and the image of the projection light L2) has anisotropy, and the direction connecting the electrodes 13a and 13b of the light source 1 is the reflection mirror 3 and the diaphragm 6. The arrangement direction of the light source 1 was specified so as to be parallel to the boundary line of. That is, when the illumination light L1 and the projection light L2 are separated, they are separated in the direction orthogonal to the longitudinal direction of the image. As a result, a larger image can be obtained within the lens effective diameter as shown in FIG. As a result, in this embodiment, it is possible to obtain a projected image with high light utilization efficiency and high image quality. Further, since the effective lens diameter can be used large, a relatively low-priced projection lens can be used, and the cost of the optical system does not increase.

Further, in this embodiment, the aperture 6a of the diaphragm 6 is provided.
Is formed into a rectangular shape extending in the longitudinal direction of the image by the light source, so that unnecessary light such as scattered light can be efficiently eliminated and the contrast of the image can be improved.

Further, in this embodiment, the reflection mirror 3 (the shape viewed from the objective lens 4 side) and the aperture 6a of the diaphragm 6 are both rectangular and the longitudinal directions thereof are parallel to each other, so that the reflection type Illumination light L incident on the liquid crystal panel 5
The parallelism of 1 is improved, which can contribute to the improvement of the contrast of the projected image. At this time, even if the reflection mirror 4 is made larger, the contrast of the projected image is slightly lowered, but the effect of this embodiment is not lost.

The shape of the opening 6a of the diaphragm 6 may be changed as shown in FIG. 5 instead of being rectangular. That is,
In FIG. 5A, the opening 6a has a trapezoidal shape, and FIG.
In FIG. 5C, the opening 6a has a semicircular shape, and in FIG. 5C, the opening 6a has an elliptical shape. In short, the opening 6a may have any shape as long as it has a long hole shape extending in the longitudinal direction of the image formed by the light source 1. If it is added, the shape of FIG. 5C among the above shapes substantially matches the image by the light source 1, so it can be said that this can most effectively eliminate unnecessary light. At the same time, the shape of the reflection mirror 3 viewed from the objective lens 4 side may be changed similarly.

(Second Embodiment) Next, only the difference between the projection type liquid crystal display device of the second embodiment and the first embodiment will be described. FIG. 6 shows the configuration of the projection type liquid crystal display device in the second embodiment. In FIG. 6, one positive meniscus lens 21 is arranged between the light source 1 and the condenser lens 2. In this case, the distance between the light source 1 and the condenser lens 2 is, for example, about 2/3 as compared with the configuration of FIG. 1 (first embodiment).

In short, the improvement of the light-collecting efficiency by shortening the focal length of the single lens is limited by the aberration and the reflection loss of the lens surface, but the use of the positive meniscus lens 21 shortens the focal length of the condenser lens 2. A brighter light source image can be obtained. According to the experiment, it was confirmed that the brightness can be increased by about 1.2 times as compared with the configuration of FIG.

(Third Embodiment) Next, only the difference between the projection type liquid crystal display device of the third embodiment and the first embodiment will be described. FIG. 7 shows the structure of the projection type liquid crystal display device in the third embodiment. In FIG. 7, the projection lens 7 of FIG. 1 is excluded. In this case, the lens effective diameter in the reflection mirror 3 and the diaphragm 6 corresponds to the diameter of the exit pupil of the objective lens 4, and the image of the illumination light L1 and the image of the projection light L2 are put in this lens effective diameter, A high quality projected image can be obtained as in the embodiment. Further, by eliminating the projection lens 7, the number of parts of the optical system can be reduced and the size can be reduced.

(Fourth Embodiment) Next, only the difference between the projection type liquid crystal display device of the fourth embodiment and the first embodiment will be described. FIG. 8 shows the structure of the projection type liquid crystal display device in the fourth embodiment. In FIG. 8, a concave mirror 22 is arranged behind the light source 1. In this case, the brightness of the projected image can be approximately doubled as compared with the case where the concave mirror 22 is not provided.

(Fifth Embodiment) Next, only the difference between the projection type liquid crystal display device of the fifth embodiment and the first embodiment will be described. FIG. 9 shows the structure of the projection type liquid crystal display device in the fifth embodiment. In FIG. 9, a mirror 23 that reflects the illumination light L1 at an angle of about 90 ° is arranged between the condenser lens 2 and the reflection mirror 3. In this case, by making the optical axis of the light source 1 and the central axis of the objective lens 4 (the central axis of the projection lens 7 are the same) substantially parallel to each other, the size of the entire apparatus can be reduced.

(Sixth Embodiment) Next, a sixth embodiment in which the present invention is embodied in a three-plate projection type liquid crystal display device will be described only in the points different from the first embodiment. FIG. 10 shows the configuration of the projection type liquid crystal display device in the sixth embodiment. In FIG. 10, the illumination light L1 that has passed through the objective lens 4 is
The light L1 is incident on a dichroic prism 25 for color-separating the light in the red (R), green (G), and blue (B) wavelength bands. Reflective liquid crystal panels 26, 27, and 28 are attached to the three exit side surfaces of the dichroic prism 25, respectively.

In such a case, the dichroic prism 26
Causes the red component of the illumination light L1 (white light) to be reflected in the downward direction of the figure and irradiate the reflective liquid crystal panel 26. In addition, the blue component is reflected in the upward direction of the drawing, and the reflective liquid crystal panel 27 is irradiated with the blue component. Further, the green component is transmitted in the left direction in the drawing and is irradiated on the reflective liquid crystal panel 28. Each of the liquid crystal panels 26 to 28 is driven by an image signal whose color is separated corresponding to each color component. And each liquid crystal panel 26-2
The reflected light of 8 is synthesized to become the projected light L2 (white light),
The projection light L2 is the objective lens 4, the diaphragm 6, and the projection lens 7.
Is projected onto the screen.

In this case, light loss due to a color filter or the like in the single plate type liquid crystal panel is reduced, and a brighter projected image can be obtained. The present invention can be embodied in the following modes in addition to the above embodiments.

(1) In the above embodiment, the aperture 6 of the diaphragm 6
Although the size of a is fixed, it may be variable. That is, when the surrounding illumination is sufficiently dark, the brightness of the projected image is slightly reduced by reducing the size of the opening 6a of the diaphragm 6, but the contrast can be improved.

(2) In the above embodiment, the metal halide lamp was used as the light source, but it may be changed to another light source such as a xenon lamp having anisotropy in the shape of the light emitting portion. (3) In the above embodiment, the PDLC is used as the reflective image device.
Although the liquid crystal element is used, another liquid crystal element may be used. Further, instead of the liquid crystal element, a scattering type image element due to film deformation may be used.

[0037]

According to the first aspect of the present invention, it is possible to obtain an excellent effect that a projected image having high light utilization efficiency and high image quality can be obtained while suppressing an increase in cost.

According to the second aspect of the invention, unnecessary light can be removed more efficiently. According to the invention of claim 3, the focal length of the first lens is shortened,
A brighter projected image can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a projection type liquid crystal display device in a first embodiment.

FIG. 2 is a perspective view showing configurations of a reflection mirror and a diaphragm.

FIG. 3 is an enlarged view showing a configuration of a light source.

FIG. 4 is a diagram of a reflection mirror and a diaphragm viewed from the objective lens side.

FIG. 5 is a diagram showing an example in which the shape of the aperture of the diaphragm is modified.

FIG. 6 is a configuration diagram showing a projection type liquid crystal display device in a second embodiment.

FIG. 7 is a configuration diagram showing a projection type liquid crystal display device in a third embodiment.

FIG. 8 is a configuration diagram showing a projection type liquid crystal display device in a fourth embodiment.

FIG. 9 is a configuration diagram showing a projection type liquid crystal display device in a fifth embodiment.

FIG. 10 is a configuration diagram showing a projection type liquid crystal display device in a sixth embodiment.

FIG. 11 is a configuration diagram showing a projection type liquid crystal display device in the related art.

FIG. 12 is a diagram of a reflection mirror and a diaphragm viewed from the objective lens side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Condenser lens as 1st lens, 3 ... Reflective mirror, 4 ... Objective lens as 2nd lens, 5 ... Reflective liquid crystal panel, 6 ... Aperture, 6a ... Aperture, 14 ... Light emission Part, L1 ... Illumination light, L2 ... Projection light.

Claims (3)

[Claims] 1. A light source having a light emitting portion having anisotropy in shape, a first lens for collecting illumination light from the light source, and reflecting the illumination light collected by the first lens. Adjacent to the reflection mirror, a reflection mirror, a reflection type image element that reflects the illumination light from the reflection mirror as projection light, a second lens that allows the incident light and the reflection light of the reflection type image element to pass therethrough, and In a projection type display device having a diaphragm arranged, the illumination light and the projection light are separated in a direction orthogonal to the longitudinal direction of the image by the light source, and the aperture of the diaphragm is imaged by the light source. A projection type display device, which is formed in the shape of an elongated hole extending in the longitudinal direction. 2. The projection display device according to claim 1, wherein the shape of the aperture of the diaphragm is made to substantially match the image formed by the light source. 3. The projection type display device according to claim 1, wherein the first lens is composed of two or more lens groups including at least one positive meniscus lens.