JP4610241B2 - Projection-type image display device - Google Patents

Description

  The present invention relates to a projection type image display apparatus.

  2. Description of the Related Art In recent years, there has been known a projection type image display device that includes a liquid crystal display element as light modulation means and projects image light that is light modulated by the liquid crystal display element onto a screen. The liquid crystal that constitutes the projection type image display device A display element using a reflective liquid crystal panel has attracted attention.

  FIG. 4 and FIG. 5 show a conventional projection type image display device as described in Patent Documents 1 and 2 using this reflection type liquid crystal panel. The conventional projection type image display device 90 includes a light source unit 91, a mirror 94 provided on the optical axis from the light source unit 91, a polarization beam splitter 95, a reflective liquid crystal panel 96, a projection lens 97, and the like. Illumination light from the light source unit 91 is incident on the polarization beam splitter 95, P-polarized light is transmitted by the reflecting surface 95 a provided on the polarization beam splitter 95, and S-polarized light is reflected. The S-polarized light reflected by the reflecting surface 95 a of the polarizing beam splitter 95 enters the reflective liquid crystal panel 96. The reflective liquid crystal panel 96 converts S-polarized light into P-polarized light to reflect the portion with high luminance (image white portion) and reflects the S-polarized light with respect to the portion with low luminance (image black portion) as it is. It is arranged to reflect. Of the illumination light reflected by the reflective liquid crystal panel 96, only P-polarized light passes through the polarization beam splitter 95 and enters the projection lens 97. As a result, only the pixels in the white portion of the image are enlarged by the projection lens 97 and projected onto the screen 98, and a large screen image is obtained.

JP 2002-268015 A JP-A-7-87427

  However, in the projection type image display apparatus as described above, the degree of polarization of the light beam emitted after the polarization separation by the polarization beam splitter is reduced due to the internal distortion of the polarization beam splitter, thereby causing color unevenness and a reduction in contrast. Has a problem. Therefore, in order to prevent such a problem, it is necessary to securely fix the polarizing beam splitter at an appropriate position so as to have a high degree of polarization. However, in the conventional projection display device, the polarization beam splitter 95 is generally fixed in the configuration as shown in FIG. 5, and the holding member 102 that holds the polarization beam splitter 95 is fixed to the casing 101. In addition, only one end face side of the polarization beam splitter 95 is cantilevered. In this configuration, the other end side is stressed downward due to the weight of the polarizing beam splitter itself, and stress distortion occurs, so that the degree of polarization is reduced and color unevenness and contrast are reduced. Conventionally, in order to reduce the stress distortion of the polarizing beam splitter, measures such as using lead glass with excellent flexibility as a transparent optical member have been taken, but it is difficult to completely eliminate the stress distortion. Using expensive lead glass hinders cost reduction.

  The present invention has been made to solve the above-mentioned problems, and is a projection-type image display that can reliably prevent a color unevenness and a decrease in contrast by reliably fixing a polarizing beam splitter and projecting a light beam having a high degree of polarization. The object is to provide the device at low cost.

In order to solve the above problems, a projection-type image display apparatus according to the present invention receives a light source that emits illumination light, and receives illumination light from the light source. A light modulation means for light-modulating the image light composed of the first and second polarization components, a polarization beam splitter having a reflecting surface that reflects the first polarization component and transmits the second polarization component; In the projection-type image display apparatus including a projection optical system that projects the second polarization component transmitted through the polarization beam splitter onto a screen and a box-shaped casing for storing the projection optical system, the polarization beam splitter has a substantially rectangular column shape. The illumination light is incident along an incident direction parallel to the vertical direction, and the image light is disposed along a projection direction orthogonal to the incident direction. Ri, while being fixed on both sides of the polarizing beam splitter along the holding direction of the incident direction and the projection direction substantially orthogonal, are respectively fixed to both side plates of the casing, both sides of the polarizing beam splitter A holding member that is fixed from the portion is provided. The holding member is preferably composed of at least two members, and the polarizing beam splitter is preferably held at two or more locations.

According to the present invention, the polarizing beam splitter is formed in a substantially rectangular column shape, and the illumination light is incident along an incident direction parallel to the vertical direction, and is along a projection direction orthogonal to the incident direction. The image light is arranged so as to be incident thereon, and is fixed to both side surfaces of the polarization beam splitter along a holding direction substantially orthogonal to the incident direction and the projection direction, and to both side plates of the casing. Since each of the holding members for fixing the polarizing beam splitter is fixed from both sides, the polarizing beam splitter is securely fixed to project a light beam with a high degree of polarization to prevent color unevenness and contrast deterioration. It is possible to provide a projection-type image display device that can be provided at low cost.

  FIG. 1 is a perspective view showing a configuration of a projection type image display apparatus of the present invention. The projection-type image display device 10 houses a light source unit 11, a mirror 12, condensing lenses 13a and 13b, a polarizing beam splitter 15, a reflective liquid crystal panel 16, a projection lens 17, support members 18a and 18b, and the like. A casing 21 and a base 22 to which the casing 21 is fixed are provided.

  As shown in FIG. 2, the light source unit 11, the mirror 12, and the condenser lenses 13 a and 13 b are located in the lower part in the casing 21. The casing 21 is formed in a box shape including a front plate 21 a, a back plate 21 b, side plates 21 c and 21 d, and a top plate 21 e, and is fixed to the upper surface of the base 22.

  The light source unit 11 includes a light source 11 a and a reflector 11 b that reflects illumination light emitted from the light source 11 a toward the mirror 12. As the light source 11a, for example, a white light source such as a xenon tube, a mercury lamp, or a metal hydride lamp is used. The mirror 12 reflects the illumination light from the light source unit 11 upward in the vertical direction. The illumination light reflected by the mirror 12 enters the polarization beam splitter 15. The condenser lenses 13 a and 13 b converge the illumination light from the light source unit 11.

  As shown in FIGS. 2 and 3, the reflective liquid crystal panel 16 and the projection lens 17 are arranged in parallel along the projection direction A of the image light with the polarization beam splitter 15 in between, and the casing 21. Located in the upper part. The reflecting surface 15a of the polarizing beam splitter 15 is formed so as to reflect S-polarized light and transmit P-polarized light, and is inclined by 45 ° with respect to the horizontal plane. Therefore, in the illumination light incident from the light source unit 11, S-polarized light is reflected by the reflecting surface 15a and emitted in the horizontal direction, and P-polarized light is emitted upward. The S-polarized light emitted from the polarization beam splitter 15 enters the reflective liquid crystal panel 16 located behind.

  The reflective liquid crystal panel 16 as the light modulation means is the same as the conventional one, and converts the S-polarized light into the P-polarized light and reflects the high-luminance portion (white image portion), and also the low-luminance portion. For (image black portion), the S-polarized light is reflected as it is. S-polarized light and P-polarized light reflected by the reflective liquid crystal panel 16 are reflected and emitted on the same optical path as the incident light, and enter the polarizing beam splitter 15 again. Of the illumination light reflected by the reflective liquid crystal panel 16, only the P-polarized light passes through the polarization beam splitter 15 and enters the projection lens 17. The reflective liquid crystal display panel 16 is fixed to the casing 21 via a support member 23 and the like.

  The support members 18 a and 18 b are located on both sides of the polarization beam splitter 15. The support members 18a and 18b are formed in a short rectangular column shape, and are bonded to both side surfaces of the polarization beam splitter 15, and are also bonded to both side surface plates 21c and 21d of the casing 21, respectively. Secure from the part. Adhesion between the polarization beam splitter 15 and the support members 18a and 18b is performed by filling silicon rubber or the like. In this way, the holding direction in which the supporting members 18a and 18b hold the polarizing beam splitter 15 is a direction perpendicular to the drawing, that is, the incident direction B of the illumination light reflected by the mirror 12, and the reflective liquid crystal panel 16. The polarization beam splitter 15 is sandwiched and held from a direction orthogonal to the projection direction A of the image light generated by the light modulation.

  The operation of the above configuration will be described below. When the projection image display apparatus 10 is turned on, illumination light is emitted from the light source unit 11 and is separated into S-polarized light and P-polarized light by the polarization beam splitter 15, and only S-polarized light is incident on the reflective liquid crystal panel 16. . An input image is displayed on the reflective liquid crystal panel 16, and the illumination light emitted from the polarization beam splitter 15 is optically modulated and reflected to image light composed of S-polarized light and P-polarized light. Of the image light generated by the reflective liquid crystal panel 16, only P-polarized light passes through the polarization beam splitter 15 and enters the projection lens 17, and an image enlarged on a large screen is projected onto the screen 24 by the projection lens 17. The As described above, the polarizing beam splitter 15 is sandwiched and held by the support members 18a and 18b from both sides, and is securely fixed at a predetermined position. Therefore, stress distortion due to the weight of the polarizing beam splitter 15 can be prevented. It is possible to keep a high degree of polarization. As a result, color unevenness and contrast reduction can be prevented. Further, since it is possible to prevent the occurrence of stress strain due to the weight of the polarizing beam splitter 15, it is not necessary to use an expensive member such as lead glass as the transparent optical member constituting the polarizing beam splitter 15. It is possible to reduce the cost.

  In the above embodiment, the support members 18a and 18b are bonded to both sides of the polarization beam splitter 15 and fixed to the casing 21, but the present invention is not limited to this, and the incident direction B of illumination light, and It is only necessary that the polarizing beam splitter 15 can be sandwiched from a direction that does not interfere with the projection direction A of the image light, and any portion of the polarizing beam splitter 15 may be held, and the shape of the support members 18a and 18b is not limited to the rectangular column shape. .

It is a perspective view which shows the structure of the projection image display apparatus of this invention. It is the longitudinal cross-sectional view which cut | disconnected the projection image display apparatus along the perpendicular direction. It is the cross-sectional view which cut | disconnected the projection image display apparatus along the horizontal direction. It is the longitudinal cross-sectional view which cut | disconnected the conventional projection type image display apparatus along the perpendicular direction. It is the cross-sectional view which cut | disconnected the conventional projection type image display apparatus along the horizontal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Projection type image display apparatus 11 Light source part 15,95 Polarization beam splitter 16,96 Reflection type liquid crystal panel 18a, 18b Support member

Claims (2)

A light source that emits illumination light; and a light modulator that receives illumination light from the light source and modulates the illumination light into image light including first and second polarization components in accordance with an input video signal; A polarizing beam splitter having a reflecting surface that reflects the first polarization component and transmits the second polarization component, and projection optics that projects the second polarization component transmitted through the polarization beam splitter onto a screen In a projection-type image display device comprising a system and a box-shaped casing for storing these,
The polarization beam splitter is formed in a substantially rectangular column shape, and the illumination light is incident along an incident direction parallel to the vertical direction, and the image light is incident along a projection direction orthogonal to the incident direction. Are fixed to both side surfaces of the polarizing beam splitter along a holding direction substantially orthogonal to the incident direction and the projection direction, and are fixed to both side plates of the casing , respectively. A projection-type image display device comprising a holding member for fixing the polarizing beam splitter from both sides. The projection image display apparatus according to claim 1, wherein the holding member includes at least two members and holds the polarization beam splitter at two or more locations.

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