JP3228626B2 - 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.

[0002]

2. Description of the Related Art A projection display apparatus uses, for example, a liquid crystal display panel as a light valve, controls the light valve to transmit light from a light source, and transmits the light transmitted through the light valve to a projection lens. This is a device that displays an image by projecting the image on an external screen or the like.

[0003] Such a projection type display device is generally known as a technique suitable for a large screen display or the like since a relatively small display device can display a large screen. As a light valve used for this,
In recent years, the use of liquid crystal display panels has become active. An example of such a projection type liquid crystal display device (liquid crystal projector) will be described below.

The liquid crystal projector uses a total of three liquid crystal display panels for displaying image components corresponding to the three primary colors RGB. White illumination light from a light source is color-separated into these liquid crystal display panels by an optical path splitting system such as a dichroic mirror and is incident on the liquid crystal display panels. The images are synthesized and enlarged and projected as an image having one natural color tone on an external screen via a projection lens system.

Alternatively, instead of using the three liquid crystal display panels described above, one liquid crystal display panel using a color filter in which RGB three-color pixels are formed in one panel is used. A method of displaying an image having a natural color component similar to the above is also known.

As a light source used in such a projection type display device, a metal halide lamp or a xenon lamp which is white light and has excellent color rendering properties is used. In general, a rotating parabolic mirror is provided behind such a light source, and the light emitted from the light source is arranged near the focal point of the rotating parabolic mirror so that the light emitted from the light source is a paraboloid of revolution. The light is reflected by the surface of the surface mirror and emitted forward as substantially parallel light. In order to remove infrared and ultraviolet components from such illumination light, a cold mirror or UV / I
Illumination light is incident on the liquid crystal display panel via the R-cut filter. In a projection display device, in order to obtain a bright projected image with good contrast and to suppress power consumption of a light source, it is necessary to efficiently supply light emitted from the light source to a light valve such as a liquid crystal display panel. In particular, in the case of a liquid crystal projector, in order to avoid problems such as non-uniformity of contrast caused by the influence of the viewing angle characteristics of the liquid crystal display panel and in-plane non-uniformity of gradation of a display image, a telecentric projection lens system is used. It is necessary to use a lens, for which the illumination light supplied from the light source must be a parallel light.

On the other hand, in order to obtain a bright projected image, it is required that the intensity of the light from the light source is high. It is known that a metal halide lamp is preferably used as a light source suitable for this purpose.

However, since the emission intensity distribution 702 of such a metal halide lamp 701 becomes maximum in the direction perpendicular to the longitudinal direction of the arc 703 (FIG. 7), the light source in the conventional projection display device is shown in FIG. As shown in the drawing, the light supplied from the arc light source 801 is once set so that the longitudinal direction of the arc coincides with the main emission direction of the illumination light.
A structure is employed in which the light is reflected by a parabolic reflecting mirror 802 having a focal point in the vicinity of 1, emitted forward as parallel light, and supplied to a liquid crystal display panel 803 in front thereof.

However, in such a conventional method, since the non-light emitting portion of the light source 801 exists on the optical axis 804, the dark portion 805 due to the shadow of the illuminating light at that portion.
Is generated and displayed as a dark image on an external screen. That is, as shown in FIG. 8, the dark portion 805 is blocked by the non-light-emitting portion of the arc light source 801 and sufficient illumination is not performed.

In order to solve such a problem, in the prior art, as shown in FIG. 9, a light emitting portion 901 of an arc light source 801 and a focus 90 of a rotating parabolic reflector 802 are used.
2 is shifted in the front-rear direction, or as shown in FIG. 10, the illumination area is reduced with parallel light by the afocal optical systems 1001 a and 1001 b, and the area of the dark portion 805 is reduced to reduce the area that appears dark. A method of reducing the size has also been proposed.

[0011]

However, in the case of the prior art shown in FIG. 9, the light used as the illumination light is not parallel light even though the rotating parabolic reflector 802 is used. The illuminating light enters the liquid crystal display panel 803 and is transmitted therethrough to be greatly affected by the viewing angle characteristics of the liquid crystal display panel 803 when used for image display, and the light transmitted through the liquid crystal display panel 803 spreads. Therefore, in order to obtain a projection image of the same brightness, a large-aperture projection lens having a smaller F-number than in the case of parallel light is required, which increases the cost and hinders miniaturization of the apparatus. Is generated.

On the other hand, in the case of the prior art shown in FIG. 10, the lens 10 constituting the afocal optical system 1001 is
Since the number of optical systems such as 01a and 1001b increases, material costs and manufacturing costs, weight and size of the device increase, and it is necessary to increase the illumination area in advance from the desired illumination area. There is a problem that a large reflecting mirror is required, which hinders miniaturization of the display device. The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a projection system capable of realizing a bright display in which the uniformity of a projected image in a screen is good, the utilization efficiency of illumination light is high, and the like. It is to provide a type display device.

[0013]

According to the present invention, there is provided a projection display apparatus comprising: a light source; a first reflecting surface having a first focal point in a light emitting portion of the light source; and a first reflecting surface of the first reflecting surface. A second reflective surface having a second focal point at a position different from the focal point; and a second reflective portion disposed at the second focal point portion (including an area within 3 mm from the focal point) and emitted from the light source and reflected by the first reflective portion. A reflecting optical system comprising: a third reflecting surface which reflects light on a surface and further reflects light reflected on the second reflecting surface on the surface and emits the light as substantially parallel light; and a light emitted from the reflecting optical system. A light valve panel for controlling the transmission of light for each pixel, and a projection lens system for enlarging or reducing light transmitted or reflected by the light valve panel and projecting the light on an external screen. .

When the first and second reflecting surfaces are spheroidal, it is desirable that the focus parameters of the first and second reflecting surfaces are set to be equal, and that the eccentricity is It is desirable to set the value equal to or larger than the value of the first reflection surface.

It is desirable that the shape of the third reflecting surface is a paraboloid of revolution, a conical shape, or any other shape of rotation.

Considering the balance with the first and second reflecting surfaces, when those reflecting surfaces are formed as paraboloids of revolution, the third reflecting surface may also be formed as a paraboloid of revolution. Needless to say, this is desirable. However, besides this, it may be approximately formed in the aforementioned conical shape or the like.

Further, the first reflecting surface and the second reflecting surface may be integrally formed so as to be continuous.
Alternatively, it is needless to say that two separate reflecting mirrors may be combined. When they are formed integrally, they are formed, for example, in a spheroidal shape, and a light source is arranged on the first focal point side, and a third reflecting surface is arranged on the second focal point side. It is also conceivable that the light reflected by the reflection surface is emitted from an opening formed in the second reflection surface.

[0018]

In the projection display device according to the present invention, a third reflection surface is arranged in an area where the shadow of the non-light emitting portion of the light source is formed in the conventional projection display device, and the third reflection surface is provided on the third reflection surface. By arranging the first and second reflecting surfaces so that light is supplied, and consequently applying the light reflected by the third reflecting surface to the area where the conventional shadow is formed, It can compensate for the lack of light in the part. As a result, it is possible to eliminate a shadowed area in the related art and obtain a uniformly bright projected image over the entire screen.

Further, in the conventional invention, 100% of the light emitted from the light source is not necessarily used, and there is a loss, but according to the present invention, almost 100% of the light emitted from the light source is present. Can be effectively led to the light valve, so that the utilization efficiency of the light emitted from the light source can be increased, and the power consumption of the light source can be reduced.
In addition, since the illumination light supplied to the light valve can be emitted as ideal illumination light that is almost parallel light, it is caused by the viewing angle characteristics of the liquid crystal display panel, for example, when a liquid crystal display panel is used for the light valve. The non-uniformity of the projected image can be eliminated or reduced, and as a result, an image display with extremely high uniformity within the screen can be realized.

Further, in the projection type display device according to the present invention, only the reflection optical system of the conventional projection type display device needs to be changed, and therefore, for example, a solution for a shadow portion using an afocal optical system, etc. Compared with the conventional liquid crystal display device, the uniformity of the brightness in the screen can be improved very easily.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the projection type display device according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a view showing an outline of the structure of a projection type display apparatus according to a first embodiment of the present invention. FIG. 1 mainly shows a light source and a reflection optical system, which are characteristic parts of the projection display apparatus according to the present invention. In the following description, for the sake of simplicity, the description will be mainly focused on the light source and the reflection optical system.

The light source portion of the projection type display device of the first embodiment comprises a first reflecting surface 1, a second reflecting surface 2, a third reflecting surface 3, and a light source 4 as main parts thereof. Are formed.

A hole is made at the center of the first reflecting surface 1 formed in the shape of a paraboloid of revolution, and a tubular arc electrode portion of the light source 4 passes through this portion. It is arranged so as to be located at the focal point 5 of the surface 1. The light emitted from the light source 4 is reflected by the surface of the first reflection surface 1 and emitted to the right in the drawing as substantially parallel light.

The second reflecting surface 2 is formed by a cylindrical reflecting surface obtained by cutting both ends of a spheroid, and one of the two focal points is located at the position of the light source 4, ie, the first reflecting surface. The focal point of the third reflection surface 3 is arranged so as to coincide with the focal point 5 of the first and the other focal point 6. The illumination light from the light source 4 reflected by the second reflecting surface 2 is applied to the surface of the third reflecting surface 3 and further reflected on the surface of the third reflecting surface 3 to become substantially parallel light. Similarly to the reflection surface 1, the light is emitted as parallel light to the right in the figure.

Here, the first reflecting surface 1 and the second reflecting surface 2
And are joined at the overlapping portion. The third reflecting surface 3 is formed in the shape of a paraboloid of revolution arranged so that the focal point is located at the focal point 6, and its maximum diameter is set to a size that almost covers the diameter of the non-light emitting portion of the light source 4. The light source 4 is fixed to the right end of the light source 4 with a heat-resistant insulating adhesive.

Of the light emitted from the light emitting portion of the light source 4 located at the focal position 5, the light reflected on the surface of the first reflecting surface 1 becomes parallel light and is emitted as parallel illumination light as described above. Then, it is supplied to the liquid crystal display panel 7 arranged outside this reflection optical system.

On the other hand, the light source light directed to the surface of the second reflecting surface 2 is reflected by the surface of the second reflecting surface 2. At this time, since the second reflecting surface 2 is a spheroid, this spheroid is used. The light reflected by the surface is emitted toward the other focal position 6. The light reflected toward the focal position 6 is further reflected on the surface of the third reflecting surface 3 where the focal point of the paraboloid of revolution is located at the focal position 6, and becomes almost parallel illumination light to the outside. The light is emitted to the liquid crystal display panel 7. In this manner, the light emitted from the light emitting portion of the light source 4 can be effectively transmitted in almost all directions by the first, second, and third reflecting surfaces 1, 2, and 3 of the reflecting optical system. And is used as parallel light to be supplied to the liquid crystal display panel 7. At this time, in the related art, the non-light emitting portion of the light source 4 has a shadow area in the illuminating light at that part, but the light reflected by the surface of the third reflecting surface 3 compensates for this. Thus, the illumination light supplied to the liquid crystal display panel 7 becomes uniformly bright illumination light over almost the entire area of the screen. As a result, an image projected on a screen outside the apparatus via the projection lens system arranged outside the liquid crystal display panel 7 is a high-quality display with extremely excellent luminance and contrast characteristics.

FIG. 2 is a diagram showing an outline of a structure as a projection display device when the light source and the reflection optical system of the first embodiment are used in a three-panel liquid crystal projector.

The light from the light source 4 is emitted from the first reflecting surface 1, the second reflecting surface 2, and the third reflecting surface 3 as described above.
The light is reflected by the reflection optical system 201 provided with the illumination light and emitted as substantially parallel illumination light. This illumination light is reflected by the cold mirror 202 as white light, and then reflected by the dichroic mirrors 203a, 203b and 203c.
The three primary colors are separated and supplied to liquid crystal display panels 7a, 7b, 7c corresponding to the respective colors. The light transmitted through each of the liquid crystal display panels 7a, 7b, and 7c is further combined through dichroic mirrors 204a, 204b, and 204c of a combining system disposed further therefrom and guided to the projection lens system 205. . Then, the image is enlarged by the projection lens system 205 and projected onto the screen 206, and an image is formed on the 206.

(Embodiment 2) FIG. 3 is a diagram showing an outline of the structure of a light source and a reflection optical system in a projection type display apparatus according to a second embodiment of the present invention. In the following description, for the sake of simplicity, the same parts as those in the first embodiment are denoted by the same reference numerals.

Each of the first reflecting surface 1, the second reflecting surface 2, and the third reflecting surface 3 is formed in the shape of a paraboloid of revolution. The first reflecting surface 1 and the light source 4 are arranged so that the light emitting part of the light source 4 is located at the focal position 5 of the first reflecting surface 1.

Further, the focal positions of the second reflecting surface 2 and the third reflecting surface 3 are both arranged so as to overlap with the second focal position 6.

Further, the relationship between the focal lengths of the respective reflecting surfaces is as follows: if the focal lengths are f ₁ , f ₂ and f ₃ , respectively.
And has a _2> f ₁ >> f _3. And the second reflecting surface 2
An opening window is formed in the center of the illuminator, and illumination light is emitted as parallel light from the opening window. The size of the opening of the second reflecting surface 2 is formed in a circular shape having a sufficiently small area as compared with the display area of the liquid crystal display panel of the projection display device in which the second reflecting surface 2 is used. .

The light emitted from the light source 4 is applied to the first reflecting surface 1.
Is reflected on the surface of the second reflecting surface 2 and is emitted forward as parallel light. The emitted light is further reflected on the surface of the second reflecting surface 2 disposed in front thereof, and The light is emitted so as to concentrate toward the focal position 6. The light emitted toward the focal position 6 in this manner is further reflected on the surface of the third reflecting surface 3 and passes through the opening of the second reflecting surface 2 as substantially parallel spot-like illumination light. The light is emitted to a liquid crystal display panel (not shown) arranged outside. As described above, in the projection type display device of the present embodiment, the parallelism is high, the light is concentrated, and the light intensity is high on the optical axis, which was shadowed by the non-light emitting portion of the light source 4 in the related art. Strong illumination light can be obtained.

FIG. 4 is a diagram showing an outline of the structure of a projection type display device using a reflection optical system and a transmission / scattering type liquid crystal display panel according to the second embodiment. In the case of the liquid crystal projector shown in FIG. 4, a Schlieren optical system that does not project scattered light onto a screen is preferably used in order for the liquid crystal display panel to be in a normal black display state. In order to enhance the contrast characteristics, it is desirable to use a point light source so that the illumination light can efficiently pass through the pinhole in the white mode display in the transmission state. However, in order to realize this without increasing the diameter of the lens. It is desirable to use illumination light close to parallel light.

FIG. 4A is a diagram showing the structure of a liquid crystal projector using such a Schlieren optical system and a transmission-scattering type liquid crystal display panel.

The light emitted from the light source system 401 is optimized by the first lens 402 for the distribution and incident angle of the illumination light with respect to the liquid crystal display panel 403, and
3, after passing through the liquid crystal display panel 403,
The light is converged again by the second lens 404 toward the pinhole of the aperture 405, enlarged through the projection lens system 406, and an image is formed on an external screen 407.

FIG. 4B shows a liquid crystal projector using the same schlieren optical system and transmission-scattering type liquid crystal display panel as described above. FIG. 4B shows a case using a reflection type optical system. . In FIG. 4B, light passing through the periphery of the liquid crystal display panel is not shown for the sake of simplicity.

The light emitted from the light source system 401 is optimized by the first lens 402, the reflection mirror 408a, and the second lens 410 to optimize the distribution and incident angle of the illumination light with respect to the liquid crystal display panel 403.
After being reflected by the liquid crystal display panel 403, the light is converged again by the second lens 410 toward the pinhole of the stop 405, is reflected by the reflection mirror 408 b, is enlarged through the projection lens system 406, and is enlarged by the external screen. 40
An image is formed on 7.

In the case of the liquid crystal projector shown in FIG. 4B, the optical system is designed so that the illumination light reflected by the reflection mirror 408a enters and reflects at an angle slightly inclined from the normal direction of the liquid crystal display panel 403. Is set. The first reflection mirror 408a on the light source side and the stop 405 exist at optically conjugate points, and these are located at the most converged portion of the light beam. In order to avoid stray light from the light source system 401, the optical axis of the light source system 401 and the projection lens system 40
The optical axis 6 is not arranged on the same axis.

As described above, the light source system 401 according to the present embodiment can be effectively used as the light source system of the liquid crystal projector in both the transmission type and the reflection type.

Although the transmission scattering type liquid crystal panel is used in the above embodiment, the light valve panel (display panel) is not limited to this. In addition to this, the light valve panel can be applied to all projection display devices having a structure using a white light source in the Schlieren optical system. For example, a type of light valve that performs black-and-white display by controlling the direction of light incident on the projection lens can be used.

Further, in this embodiment, the shape of the opening of the second reflection surface 2 is circular. However, if the opening is formed in the same opening area as the screen display area of the liquid crystal display panel, the shape is circular. It is not limited to only. For example, even if the opening has a shape similar to the outer shape of the liquid crystal display panel, the light reflected by the first reflection surface 1 is incident on the liquid crystal display panel as parallel light, so that the same effect as in the above embodiment can be obtained. .

(Embodiment 3) FIG. 5 is a view showing the structure of a light source system, that is, a light source and a reflection optical system of a transmission type display device according to a third embodiment of the present invention.

In this projection type display device, since the first reflecting surface 1 and the second reflecting surface 2 have the same eccentricity and the same focus parameter, as shown in FIG. It is formed in a body shape (egg shell shape). That is, in the reflection optical system, the first reflection surface 1 and the second reflection surface 2 are formed not as separate bodies but as one body, that is, as a continuous curved surface. In FIG. 5, for simplicity of description, the same parts as those in the first and second embodiments are denoted by the same reference numerals.

The light source light emitted from the light emitting portion of the light source 4 located at the first focal position 5 is transmitted to the first reflection surface 1 or the second reflection surface 1.
First, the light is reflected by the reflecting surface 2 and is focused toward the second focal position 6. A third reflecting surface 3 is arranged at the focal position 6 and the third reflecting surface 3 is a conical reflecting mirror. Therefore, light is reflected on the surface of the third reflecting surface 3. Is reflected and emitted to the outside as shown in FIG. At this time, since the surfaces of the first reflecting surface 1 and the second reflecting surface 2 are spheroidal and the surface of the third reflecting surface 3 is conical, the surface of the third reflecting surface 3 is formed. In general, the light reflected by the light and emitted to the outside is emitted with a slight radial dispersion. At this time, the maximum angle of radiation is the third reflecting surface 3
Is defined by the angle of Therefore, by appropriately setting the shape of the third reflecting surface 3, the angle of the emitted light can be controlled to an appropriate value. At this time, the third reflection surface 1 and the second reflection surface 2 are considered in consideration of the curvature and the like.
Needless to say, the conical shape of the reflecting surface 3 may be set. In this way, it is possible to obtain a light emission direction distribution and an illuminance distribution suitable for a light source device of an optical system that does not necessarily require strict parallel light.

In the case of the third embodiment, since the first reflecting surface 1 and the second reflecting surface 2 have substantially the same shape,
There is an advantage that the manufacturing is simplified and the cost can be reduced.

By changing the shape of the third reflecting surface 3 to various shapes such as having a negative curvature other than the conical shape, it is possible to control the emission direction and the illuminance distribution of the illumination light. It is possible.

(Embodiment 4) In the above embodiment, the light source 4 is arranged so that its longitudinal direction is substantially parallel to the optical axis of the light emitting direction of the light source system. It is needless to say that the present invention is not limited to this. It goes without saying that the light source 4 may be arranged so that its longitudinal direction intersects the main light emitted from the light source 4 in the vertical direction. An example of such a structure is shown as a fourth embodiment. In this case, as shown in the outline of the structure in FIG. 6, the third reflecting surface 3 is constituted by reflecting surfaces having two different shapes.

That is, the surface of the portion receiving the reflected light from the second reflection surface 2 is formed as a paraboloid of revolution, and the surface facing the light source 4 has the center of the radius of curvature of the surface as the first. Reflective surface 1
And the focal length of the first reflecting surface is f and the radius of curvature is r, f> r.

The light emitted from the light emitting portion of the light source 4 is reflected by the first reflecting surface 1 and the second reflecting surface 2 to form the third reflecting surface 3
a, and is emitted to the outside as substantially parallel light on the surface of the third reflection surface 3a. This substantially parallel light is used as illumination light. On the other hand, the light applied to the spherical surface 3 b in front of the light source 4, that is, on the back surface side of the third reflective surface 3 is reflected by the spherical surface 3 b and is reflected again by the first reflective surface 1. At this time, from the relationship of f> r, the reflected light is reflected forward without being hindered by the third reflecting surface,
The light is reflected directly or on the second reflecting surface 2 and the third reflecting surface 3, and emitted to the outside of the reflecting optical system as substantially parallel light.

Instead of providing the spherical reflecting mirror 3b on the back surface of the third reflecting surface 3, the front portion of the spherical glass shield sealing the light emitting portion of the light source 4 has high light reflectivity such as Al or Ag. The reflective film may be formed by evaporating a material.

Even with such a structure, the light emitted from the light source 4 is not hindered by the back surface of the third reflecting surface 3 and is substantially 100% as light source light supplied by the light source 4.
It is possible to obtain bright illumination light by making effective use of%.

[0055]

As described above, according to the present invention, according to the present invention, a projection type display which has a good uniformity of a luminance distribution of a projection image within a screen and a high display efficiency with high utilization efficiency of illumination light. A display device can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a light source system (reflection optical system and light source) in a projection display device according to a first embodiment.

FIG. 2 is a diagram showing a structure of a scattering type projection type liquid crystal display device using the light source system of the first embodiment.

FIG. 3 is a diagram illustrating a structure of a light source system in a projection display device according to a second embodiment.

FIG. 4 is a diagram showing an outline of the structure of a projection display device using a light source system according to a second embodiment.

FIG. 5 is a diagram showing an outline of the structure of a light source system in a projection display device according to a third embodiment.

FIG. 6 is a diagram showing a structure of a light source system of a fourth embodiment of the projection display apparatus according to the present invention.

FIG. 7 is a diagram showing a light emission intensity distribution of a conventional light source system.

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

FIG. 9 is a diagram showing a conventional projection display device.

FIG. 10 is a diagram showing a conventional projection display device.

[Explanation of symbols]

 1... 1st reflection surface 2... 2nd reflection surface 3... 3rd reflection surface 4... Light source 5... 1st focus 6. Two focuses,

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Watanabe 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Toshiba Corporation Microelectronics Research Laboratory (56) References JP-A-5-34599 (JP, A) Kaihei 3-168628 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1335-1/13363 G02F 1/13 505 G03B 21/14

Claims (1)

(57) [Claims] A light source; a first reflecting surface having a first focal point in a light emitting portion of the light source; and a second reflecting surface located at a position different from the first focal point of the first reflecting surface.
A second reflection surface having a focal point, and a surface disposed at the second focus portion, for emitting light emitted from the light source, reflected by the first reflection surface, and further reflected by the second reflection surface. A reflection optical system including a third reflection surface that reflects light at the outside and emits the light to the outside; a light valve panel that controls transmission of light emitted and supplied from the reflection optical system for each pixel; A projection lens system for enlarging or reducing light transmitted or reflected by the light valve panel and projecting the light onto a screen.