JP2009157268A - Projection type liquid crystal display device - Google Patents

Abstract

To provide a projection type liquid crystal display device that performs image display using light of each color emitted from a plurality of solid-state light sources with a small device configuration.
In a projection type liquid crystal display device that displays images by irradiating light of each color emitted from a plurality of solid light sources 3r, 3g, 3b to reflective light valves 2r, 2g, 2b, the solid light sources 3r, 3g. , 3b to the reflection type light valves 2r, 2g, 2b, a columnar optical element for uniformizing the light intensity distribution of the light emitted from the solid light sources 3r, 3g, 3b, and the columnar optical element It is arranged between relay lens groups 60r, 60g, 60b having a plurality of relay lenses for guiding the emitted light to the reflection type light valves 2r, 2g, 2b, and the relay lenses of the relay lens groups 60r, 60g, 60b. And folding mirrors 7r, 7g, and 7b that fold the optical path.
[Selection] Figure 1

Description

  The present invention relates to a projection type liquid crystal display device using a solid light source emitting a single wavelength and a reflective light valve.

  As one of the projection type liquid crystal display devices, there is a three-plate reflection type liquid crystal display device using a reflection type polarizing plate using a xenon lamp, an ultra high pressure mercury lamp or the like as a light source. In such a reflective liquid crystal display device, red, green, and blue reflective liquid crystal light valves are used. Therefore, each color light of red light, green light, and blue light is used in the optical system from the light source to the light valve. Separation means for separating them is required. For this reason, in the three-plate reflective liquid crystal display device, it is difficult to reduce the size of the optical system from the light source to the light valve.

  In order to solve the above problems, a projection type image display apparatus has been proposed in which an optical system from a light source including three wavelengths to a spatial light modulator is miniaturized. The projection type image display device includes a reflective polarizing plate for each color light of red light, green light, and blue light, and a color combining optical system that color-synthesizes image light reflected by each reflective polarizing plate. ing. The reflective polarizing plate transmits the P-polarized light component or the S-polarized light component for each color light that has passed through the color separation optical system, and makes it incident on the reflective spatial light modulator corresponding to the light of each color. Furthermore, each reflection type spatial light modulation element reflects the image light of each color, which is polarization-modulated according to the image signal of each color light, to the color synthesis optical system side (see, for example, Patent Document 1).

JP 2007-3809 (3rd page, 4th page, FIG. 1)

  However, the above conventional technique is a method that can be applied only when the light source is a light source including three wavelengths. When light beams emitted from a plurality of solid light sources having different wavelengths are used, from the solid light source to the light valve. However, this optical system requires a photosynthesis means, which increases the size of the apparatus.

  The present invention has been made in view of the above, and an object thereof is to obtain a projection-type liquid crystal display device that performs image display using light of each color emitted from a plurality of solid-state light sources with a small device configuration. .

  In order to solve the above-described problems and achieve the object, the present invention provides a projection-type liquid crystal display device that displays an image by irradiating a reflective light valve with light of each color emitted from a plurality of solid-state light sources. A columnar optical element disposed between the light paths from the solid light source to the reflective light valve to uniform the light intensity distribution of the light emitted from the solid light source, and the light emitted from the columnar optical element to reflect the light A relay lens group having a plurality of relay lenses led to a mold light valve, and a mirror disposed between the relay lenses of the relay lens group to bend the optical path of the light.

  According to the present invention, since the mirror that bends the optical path of the light is disposed between the relay lenses, there is an effect that the device configuration can be reduced.

  Embodiments of a projection-type liquid crystal display device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment FIG. 1 is a diagram showing a schematic configuration of a projection type liquid crystal display device according to an embodiment of the present invention. In the present embodiment, for convenience of explanation, the direction in which light is emitted from the solid light sources 3r, 3g, 3b is the x direction, the direction in which light is incident on the reflective light valves 2r, 2b is the z direction, and the reflective type The direction in which light enters the light valve 2g will be described as the y direction.

  In the projection type liquid crystal display device 1 of the present embodiment, a mirror that turns back light is provided between relay lenses arranged between the reflection type light valves 2r, 2g, 2b and the solid light sources 3r, 3g, 3b. This is a projection-type image display device.

  The projection type liquid crystal display device 1 includes solid state light sources 3r and 3g for irradiating light (red light, green light and blue light) to the reflection type light valves 2r, 2g and 2b and the reflection type light valves 2r, 2g and 2b. , 3b, relay lens groups 60r, 60g, 60b, folding mirrors 7r, 7g, 7b, reflective polarizing plates 8r, 8g, 8b, a light combining element 9, and a projection optical system 10. ing.

  The relay lens groups 60r, 60g, and 60b, the folding mirrors 7r, 7g, and 7b, and the reflective polarizing plates 8r, 8g, and 8b, respectively, emit light from the solid light sources 3r, 3g, and 3b to the reflective light valves 2r, 2g, and 2b. It is arranged on the optical path. In FIG. 1, two relay lenses 6r1, 6r4, 6g1, 6g4, 6b1, and 6b4 are illustrated as the relay lens groups 60r, 60g, and 60b. However, the relay lens groups 60r, 60g, and 60b include at least three. It consists of a single relay lens.

  In the projection type liquid crystal display device 1 of the present embodiment, folding mirrors 7r, 7g, and 7b for reducing the size of the projection type liquid crystal display device 1 are arranged in each of the relay lens groups 60r, 60g, and 60b. The folding mirrors 7r, 7g, and 7b are mirrors that change the direction of the optical axis by reflecting the light emitted from the solid light sources 3r, 3g, and 3b toward the reflective light valves 2r, 2g, and 2b.

  Light (monochromatic light) emitted from the solid light sources 3r, 3g, and 3b is sent to the relay lens groups 60r, 60g, and 60b, reflected by the folding mirrors 7r, 7g, and 7b, and reflected by the reflection type polarizing plates 8r and 8g. , 8b are sent to the back surface (transmission surface). Further, light from the reflective polarizing plates 8r, 8g, and 8b is sent to the reflective light valves 2r, 2g, and 2b from the surface (polarization separation surface or a surface that reflects only specific linearly polarized light). The light from the reflective polarizing plates 8r, 8g, and 8b is reflected by the reflective light valves 2r, 2g, and 2b and sent to the surface side of the reflective polarizing plates 8r, 8g, and 8b. The light is reflected by 8r, 8g, and 8b and sent to the light combining element 9. The light synthesizing element 9 synthesizes the light sent from the respective reflective polarizing plates 8r, 8g, 8b and sends it to the projection optical system 10, and the projection optical system 10 sends the light from the light synthesizing element 9 to a screen (not shown). )

  As described above, in this embodiment, the folding mirrors 7r, 7g, and 7b are arranged in the relay lens groups 60r, 60g, and 60b, and the light is reflected by the folding mirrors 7r, 7g, and 7b to change the direction of the optical axis. ing. Thereby, red light, green light, and blue light each form an optical path with two straight lines. Therefore, the optical path is formed in a small area as compared with the case where the optical path is formed by only one straight line.

  Next, a configuration when the projection type liquid crystal display device 1 is viewed from the x direction, a configuration when viewed from the y direction, and a configuration when viewed from the z direction will be described. 2 is a diagram illustrating a configuration when the projection type liquid crystal display device is viewed from the x direction, and FIG. 3 is a diagram illustrating a configuration when the projection type liquid crystal display device is viewed from the y direction. These are figures which show the structure at the time of seeing a projection type liquid crystal display device from az direction. 2 shows the projection type liquid crystal display device 1 when the projection type liquid crystal display device 1 is viewed from the front (side face F1) of FIG. 3 shows the projection type liquid crystal display device 1 when the projection type liquid crystal display device 1 is viewed from the lateral surface (side surface F2) side of FIG. 4 shows the projection type liquid crystal display device 1 when the projection type liquid crystal display device 1 is viewed from the bottom side of FIG.

  As shown in FIG. 2 to FIG. 4, the projection type liquid crystal display device 1 includes a reflection type light valve 2r, 2g, 2b, a solid light source 3r, 3g, 3b, and a reflection type light valve from the solid light source 3r, 3g, 3b. Condensing lens groups 4r, 4g, 4b arranged on the optical path of light reaching 2r, 2g, 2b, and columnar optical elements 5r, 5g, 5b arranged in the rear stage of the condensing lens groups 4r, 4g, 4b; The relay lenses 6r1 to 6r4, 6g1 to 6g4, 6b1 to 6b4 (the relay lens groups 60r, 60g, and 60b shown in FIG. 1) and the folding mirrors 7r and 7g that are arranged at the subsequent stage of the columnar optical elements 5r, 5g, and 5b. , 7b, reflection type polarizing plates 8r, 8g, 8b arranged in the rear stage of the relay lens groups 60r, 60g, 60b, a light combining element 9, and a projection optical system 10.

  The solid light sources 3r, 3g, and 3b are light sources such as LEDs (Light Emitting Diodes) that emit red light, green light, and blue light, respectively. The solid light sources 3r, 3g, 3b may be solid light sources having specific wavelengths, respectively, and may be laser light as well as LEDs. For example, the solid light source 3g is a light source having a peak wavelength only in the vicinity of 530 nm. In the present embodiment, the case where the solid light sources 3r, 3g, 3b are LEDs will be described.

  The light path of the red light is the condenser lens group 4r, the columnar optical element 5r, the relay lens group 60r, the folding mirror 7r, the reflective polarizing plate 8r, and the reflective light valve 2r. The light path of the green light is the condensing lens group 4g, the columnar optical element 5g, the relay lens group 60g, the folding mirror 7g, the reflective polarizing plate 8g, and the reflective light valve 2g. The light path of the blue light is the condenser lens group 4b, the columnar optical element 5b, the relay lens group 60b, the folding mirror 7b, the reflective polarizing plate 8b, and the reflective light valve 2b.

  Each of the condenser lens groups 4r, 4g, and 4b is composed of four condenser lenses. When a solid light source having a large divergence angle, such as an LED, is used as the solid light sources 3r, 3g, 3b, the first condensing lens of each of the condensing lens groups 4r, 4g, 4b (light first reaches the light path). The condenser lens (first condenser lens) is an aspherical lens. Thereby, it is possible to improve the light collection efficiency to the columnar optical elements 5r, 5g, and 5b. When an aspherical lens is used as the first condenser lens of each of the condenser lens groups 4r, 4g, 4b, the influence of the heat generated from the solid light sources 3r, 3g, 3b is taken into consideration. It is preferable to use glass. When glass is used for the condensing lens, the multi-coating for reducing the interface reflection of the condensing lens is not peeled off by heat like the plastic lens.

  Further, when the first condenser lens of each of the condenser lens groups 4r, 4g, and 4b is a glass aspheric lens, the projection is performed by using two more spherical lenses (second and third lenses). The liquid crystal display device 1 can be downsized. Therefore, it is preferable that the projection type liquid crystal display device 1 includes the condenser lens groups 4r, 4g, and 4b by at least three condenser lenses.

  The columnar optical elements 5r, 5g, and 5b have a uniform light intensity distribution in an optical section of light that has passed through the condenser lens groups 4r, 4g, and 4b (in a plane orthogonal to the central light traveling on the optical axis C1 described later). It has a function to reduce (unevenness in illuminance).

  The columnar optical elements 5r, 5g, 5b are elements made of a transparent material such as glass or resin. The columnar optical elements 5r, 5g, and 5b may be, for example, square columnar rods (columnar members whose cross-sectional shape is a quadrangle) configured so that the inner side of the side wall is a total reflection surface, and the reflection surface is the inner side. A pipe (tubular member) having a quadrangular cross-sectional shape combined in a cylindrical shape may be used.

  When the columnar optical elements 5r, 5g, and 5b are square columnar rods, the light is reflected a plurality of times using the total reflection action between the transparent material and the air interface, and then the emission end (injection port). The light is emitted from. When the columnar optical element 5g is a pipe having a quadrilateral cross-sectional shape, the light is emitted from the emission end after reflecting light a plurality of times by using the reflection action of the surface mirror facing inward.

  If the columnar optical elements 5r, 5g, and 5b have an appropriate length in the light traveling direction, the light reflected a plurality of times inside is superimposed and irradiated near the exit end of the columnar optical elements 5r, 5g, and 5b. A substantially uniform intensity distribution is obtained in the vicinity of the exit ends of the columnar optical elements 5r, 5g, 5b. Light emitted from the exit end having the substantially uniform intensity distribution is guided to the reflection type light valves 2r, 2g, 2b by the relay lens groups 60r, 60g, 60b.

  Each of the relay lens groups 60r, 60g, and 60b is composed of four relay lenses. The relay lens group 60r includes relay lenses 6r1 to 6r4, the relay lens group 60g includes relay lenses 6g1 to 6g4, and the relay lens group 60b includes relay lenses 6b1 to 6b4. Since the relay lens groups 60r, 60g, and 60b have the same configuration, the configuration of the relay lens group 60g will be described here.

  In the relay lens group 60g, as shown in FIG. 4, a predetermined interval is provided between the relay lens 6g2 and the relay lens 6g3 so that the folding mirror 7g in the y direction does not interfere with the relay lens. Further, by providing a distance of, for example, 5 mm or more between the relay lens 6g1 and the relay lens 6g2, it is possible to arrange a polarizing plate (a polarizing plate 20g described later) that improves the contrast in front of the reflective polarizing plate 8g. It becomes. The polarizing plate 20g has the function of aligning the polarization axis of the light emitted from the columnar optical element 5g, has the function of transmitting the p wave of linearly polarized light, and absorbing or reflecting the s wave of the linearly polarized light. In the projection type liquid crystal display device 1, for example, the contrast of green light is improved by disposing the polarizing plate 20g before the reflective polarizing plate 8g. Further, with respect to the red light path and the blue light path as well, the contrast of red light and blue light is improved by disposing a polarizing plate (not shown) in front of the reflective polarizing plates 8r and 8b as in the green light path. In the projection type liquid crystal display device 1, a PBS (polarization beam splitter) (PS polarization conversion element) may be disposed instead of the reflection type polarizing plates 8r, 8g, 8b.

  The folding mirror 7r is disposed, for example, between the relay lenses 6r2 and 6r3, the folding mirror 7g is disposed, for example, between the relay lenses 6g2 and 6g3, and the folding mirror 7b is disposed, for example, between the relay lenses 6b2 and 6b3. Is arranged.

  The reflection type light valves 2r, 2g, and 2b are obtained by arranging a large number (for example, several hundred thousand) of liquid crystal display elements corresponding to each pixel of image light to be projected on a plane, and pixel information (related to each pixel). By operating each liquid crystal display element in accordance with (information), image light corresponding to the image information is emitted based on the incident light.

  The light synthesizing element 9 is disposed at the subsequent stage of the reflective polarizing plates 8r, 8g, and 8b and the reflective light valves 2r, 2g, and 2b, and receives red light, green light, and blue light from the reflective polarizing plates 8r, 8g, and 8b. The image lights are combined and sent to the projection optical system 10. The projection optical system 10 enlarges and projects the light emitted from the light combining element 9 onto the screen.

  Next, the operation of the projection type liquid crystal display device 1 will be described. Since each of the optical paths of RGB (red, green, and blue) is an optical path having the same configuration, the optical path of green light will be described as an example of the optical path of the projection type liquid crystal display device 1 here.

  FIG. 5 is a diagram for explaining the operation of the projection type liquid crystal display device. FIG. 5 shows a case where the optical path of the green light of the projection type liquid crystal display device 1 is viewed from the z direction. The light emitted from the solid light source 3g travels in the x direction and reaches the condenser lens group 4g. The light from the solid light source 3g sequentially passes through the four condensing lenses in the condensing lens group 4g and is sent to the columnar optical element 5g. The columnar optical element 5g uniformizes the light intensity distribution in the light section of the light that has passed through the condenser lens group 4g.

  The columnar optical element 5g emits light having a uniform light intensity distribution from the exit end and sends it to the relay lens group 60g side. The light from the columnar optical element 5g is sequentially passed through the relay lens 6g1, the relay lens 6g2, and the polarizing plate 20g. At this time, the polarizing plate 20g aligns the polarization axis of the light emitted from the columnar optical element 5g, transmits the p wave of the linearly polarized light, and absorbs or reflects the s wave of the linearly polarized light. Thereby, the polarizing plate 20g improves the contrast of green light.

  Further, the light that has passed through the relay lens 6g2 is reflected by the folding mirror 7g and bent from the x direction to the y direction. The light bent in the y direction is sequentially passed through the relay lens 6g3 and the relay lens 6g4.

  The light that has passed through the relay lens 6g4 is sent to the back side of the reflective polarizing plate 8g, passes through the reflective polarizing plate 8g, and is sent to the reflective light valve 2g. The reflection type light valve 2g emits (reflects) image light according to image information based on incident light by operating each liquid crystal display element according to pixel information. The image light (green light) from the reflective light valve 2g is sent to the surface side of the reflective polarizing plate 8g, reflected by the reflective polarizing plate 8g, and sent to the photosynthetic element 9.

  Similarly, light emitted from the solid light sources 3r and 3b is sent to the light combining element 9 as red light image light and blue light image light. The light synthesizing element 9 synthesizes each image light of red light, green light, and blue light sent from each of the reflection type polarizing plates 8r, 8g, 8b and sends it to the projection optical system 10, and the projection optical system 10 The light from the element 9 is enlarged and projected onto the screen.

  Next, the locus and interference of light (light rays) traveling through the projection type liquid crystal display device 1 will be described. FIG. 6 is a diagram for explaining the interference of light rays and the arrangement position of the relay lens. FIG. 6 shows a case where the projection type liquid crystal display device 1 is viewed from the x direction. In FIG. 6, each arrow (single arrow) indicating one direction indicates a rough locus of the light beam. The intervals 30g and 30b indicate the distance from the intersection of the central axis of the reflective light valves 2g and 2b and the reflective polarizing plates 8g and 8b to the photosynthetic element 9. For example, the region 30 and the region 31 are regions in which the light beam in one optical path may be interfered by a lens arranged on the other optical path.

  The region 30 is a region where the light beam immediately after being emitted from the relay lens 6b3 and the relay lens 6g4 may interfere with each other. Further, the region 31 is a region in which the light beam immediately after being emitted from the relay lens 6g3 and the relay lens 6b4 may interfere with each other. Accordingly, a predetermined distance is provided between the relay lens 6g3 and the relay lens 6g4 and between the relay lens 6b3 and the relay lens 6b4 in consideration of the interference of lenses in other optical paths.

  In other words, in the relay lenses 6g1 to 6g4 of FIG. 5, the relay lens group 60g is installed in the projection type liquid crystal display device 1 in consideration of the distance between the relay lens 6g3 and the relay lens 6g4. Further, in the relay lenses 6g1 to 6g4, in order to arrange the folding mirrors 7r, 7g, and 7b, the relay lens group 60g is replaced with the projection type liquid crystal display device 1 in consideration of the distance between the relay lens 6g2 and the relay lens 6g3. Install it inside.

  In consideration of the distance between the two relay lenses described above, the relay lens groups 60r, 60g, and 60b can each be constituted by three relay lenses (spherical lenses). The back focus of the projection optical system 10 is shorter when the reflective light valves 2r, 2g, and 2b are irradiated with the same amount of light than when the three relay lenses are used, that is, when the imaging performance is equivalent. Become. Therefore, in the present embodiment, each of the relay lens groups 60r, 60g, and 60b is composed of four relay lenses. In addition, by using two spherical lenses (relay lenses 6g1 and 6g2), the imaging performance of the light emitted from the columnar optical element 5g on the reflective light valve 2g is improved. In addition, by using two spherical lenses (relay lenses 6b1 and 6b2), the imaging performance of the light emitted from the columnar optical element 5b on the reflective light valve 2b is improved.

  In order to efficiently guide light to the screen, it is preferable that the illuminance distribution on the reflective light valves 2g and 2b, which is conjugate with the screen, is uniform. In this case, the imaging performance on the reflective light valves 2g and 2b is improved, and the illuminance distribution in the peripheral portion on the reflective light valves 2g and 2b is not blurred. Accordingly, the amount of light applied to the reflective light valves 2g and 2b increases as compared with the case where the peripheral portion is not imaged.

  Here, the relay lens groups 60r, 60g, 60b are used in the case where three spherical lenses are used for each of the relay lens groups 60r, 60g, 60b and the imaging performance on the reflection type light valves 2r, 2g, 2b is improved. The configuration of will be described. 7 and 8 are diagrams for explaining the configuration of the relay lens group when three spherical lenses are used in the relay lens group. In FIGS. 7 and 8, for convenience of explanation, illustration of the optical path of red light, the folding mirrors 7g and 7b, the constituent elements before the columnar optical elements 5g and 5b, and the like are omitted. In FIG. 7 and FIG. 8, each single arrow indicates a rough trajectory of the light beam. In the present embodiment, when three spherical lenses are used for each of the relay lens groups 60r, 60g, 60b, the relay lenses 6r1, 6r3, 6r4, the relay lenses 6g1, 6g3, 6g4, and the relay lenses 6b1, 6b3, 6b4. Is used.

  In the projection type liquid crystal display device 1, in order to satisfy the imaging performance on the reflection type light valves 2g and 2b, the front side of the relay lenses 6g4 and 6b4 (relay lens 6g3 and 6b3 side) (hereinafter, the front stage). In order to shorten the back focus of the projection optical system 10, as shown in FIG. 6, the rear side of the relay lenses 6g4 and 6b4 (the reflective polarizing plates 8g and 8b side) is preferable. ) Surface (hereinafter referred to as a rear surface) is preferably a convex surface.

  When the relay lens groups 60g and 60b have a three-lens configuration, as shown in FIG. 7, when the front surface of the relay lenses 6g4 and 6b4 is a convex surface, the projection optical system 10 has the same back focus as in FIG. Then, light rays are emitted by the relay lenses 6g4 and 6b4. Therefore, when the front surfaces of the relay lenses 6g4 and 6b4 are convex surfaces, the intervals 40g and 40b between the light combining element 9 and the reflective polarizing plates 8g and 8b are longer than the intervals 30g and 30b shown in FIG. There is a need to.

  As shown in FIG. 8, when the rear surface of the relay lenses 6g4 and 6b4 is a convex surface, the back focus (intervals 41g and 41b) of the projection optical system 10 becomes long. When the projection type liquid crystal display device 1 in FIG. 7 and the projection type liquid crystal display device 1 in FIG. 8 are compared, the intervals 41g and 41b in FIG. 8 need to be longer than the intervals 40g and 40b in FIG. The back focus length of the projection optical system 10 is also increased. As described with reference to FIGS. 7 and 8, if the back focus of the projection optical system 10 is set longer than a predetermined value, the imaging performance is improved, that is, the amount of light applied to the reflective light valves 2g and 2b is improved. The relay lens groups 60g and 60b can be composed of three lenses.

  As described above, in the present embodiment, since the folding mirrors 7r, 7g, and 7b are used in the projection-type liquid crystal display device 1, it is possible to reduce the size of the device. For example, as shown in FIG. 5, the folding mirror 7g bends the optical axis C1 in the y direction, whereby the height of the optical path for propagating green light in the y direction can be shortened in the projection liquid crystal display device 1. It becomes. 2 to 4, the folding mirrors 7r and 7b fold the optical axis in the z direction, whereby the depth in the z direction of the optical path for propagating red light and blue light in the projection type liquid crystal display device 1. Can be shortened.

  Here, an example of the effect produced by disposing the folding mirrors 7r and 7b in the projection type liquid crystal display device 1 will be described. 9 and 10 are diagrams for explaining the dimensions of the projection type liquid crystal display device. 9 and 10, the outer frame of the projection type liquid crystal display device 1 (a casing for storing the components) is indicated by a casing 50 and a casing 51, respectively. Note that the casing 50 and the casing 51 are the same casing and have different perspective directions. FIG. 9 is a yz plan view of the projection liquid crystal display device 1 (viewed from the x direction), and FIG. 10 is a zx plan view of the projection liquid crystal display device 1 (viewed from the y direction). Show. In the present embodiment, the projection type liquid crystal display device 1 projects an image onto the screen in the state shown in FIG. 10 (installation state in which the zx plane is the bottom surface).

  As shown in FIG. 9, in the projection type liquid crystal display device 1, the optical path is formed in the x direction by disposing the constituent elements in the previous stage relative to the folding mirrors 7 r, 7 g, 7 b in the x direction (direction perpendicular to the drawing). Therefore, the depth in the z direction and the height in the y direction of the projection type liquid crystal display device 1 can be reduced. Further, the dimension of the casing 50 in the x direction and the dimension of the casing 50 in the y direction, the difference between the dimension of the casing 50 in the x direction and the dimension of the casing 50 in the z direction, the dimension of the casing 50 in the y direction, and By reducing the difference in dimension in the z direction of the housing 50, the side surface (yz plane, zx plane) and the upper surface (xy plane) of the housing 50 can be made closer to a square. For example, by reducing the height in the y direction and the z direction of the housing 50 and reducing the difference between the width in the x direction and the depth dimension in the z direction, the shape (side surface) of the housing 50 in the zx plane is reduced. Approach the square. Thereby, since the projection type liquid crystal display device 1 approaches a cube, the projection type liquid crystal display device 1 can be miniaturized.

  FIG. 10 shows a top view of the projection type liquid crystal display device 1 placed on the floor. The projection optical system 10 is disposed, for example, on the end side in the x direction in the housing 51. In the present embodiment, one folding mirror 7r, 7g, 7b is disposed between the relay lens groups 60r, 60g, 60b, so that it is not necessary to form each optical path with only one straight line. Therefore, it is possible to greatly reduce the size (volume, etc.) of the projection type liquid crystal display device 1. For example, if the folding mirrors 7r and 7b are not provided, the depth dimension in the z direction of the projection type liquid crystal display device 1 becomes large, resulting in a structure with very poor installation properties.

  Conventionally, when a reflective light valve is used, the back focus of the projection optical system is longer than when a transmissive light valve is used. In the present embodiment, by making the rear surface of the relay lenses 6r4, 6g4, 6b4 convex, the back focus of the projection optical system 10 can be shortened, and the projection type liquid crystal display device 1 has a reflective light valve 2r. , 2g, and 2b, the length of the projection optical system in the z direction (depth dimension when the screen is viewed from the front) is shortened, and the projection optical system is reduced.

  Next, the reflective polarizing plates 8r, 8g, 8b, the light combining element 9, and the polarized light on the optical path will be described. FIG. 11 is a diagram for explaining the polarized light on the optical path. FIG. 11 shows a case where the projection type liquid crystal display device 1 is viewed from the x direction. In FIG. 11, the single arrows indicated by dotted lines are respectively p-polarized light p1, and the single arrows indicated by solid lines in FIG. 11 are respectively s-polarized light s1.

  In the projection type liquid crystal display device 1, in order to improve the contrast of image light to be displayed, for example, light incident on the reflective polarizing plates 8r, 8g, and 8b is changed to p-polarized light p1. In the present embodiment, as described above, the polarizing plates 20r, 8g, and 8b are disposed between the solid light sources 3r, 3g, and 3b and the reflective polarizing plates 8r, 8g, and 8b. The light incident on the light is p-polarized light. In the columnar optical elements 5r, 5g, and 5b, the light intensity is made uniform. The polarizing plate 20g and the like are preferably disposed downstream of the columnar optical elements 5r, 5g, and 5b in order to reduce disturbance of the polarization axis of the light due to the columnar optical elements 5r, 5g, and 5b. Since polarized light is separated by the reflective polarizing plates 8r, 8g, and 8b, the polarizing plate 20g and the like may be disposed in front of the columnar optical elements 5r, 5g, and 5b.

  As shown in FIG. 11, when the reflective light valve 2g does not rotate the polarization axis, the incident p-polarized light p1 is emitted from the reflective light valve 2g in the state of p-polarized light p1. Accordingly, the p-polarized light p1 emitted from the reflective light valve 2g is transmitted through the reflective polarizing plate 8g, and the image light does not reach the light combining element 9. On the other hand, when the polarization axis of the incident p-polarized light p1 is rotated by 90 degrees as in the reflective light valves 2r and 2b shown in FIG. 11, the image light is reflected in the state of the s-polarized light s1. , 2b and reflected by the reflective polarizing plates 8r, 8b, and the image light reaches the light combining element 9. Therefore, in the projection type liquid crystal display device 1, the reflection type light valves 2r, 2g, and 2b are configured to rotate the polarization axis of the p-polarized light p1 incident on the reflection type light valves 2r, 2g, and 2b by 90 degrees. Keep it. For convenience of explanation, the case where the reflection type light valves 2r, 2g, and 2b do not rotate the polarization axis or the case that they are rotated by 90 degrees has been described. However, in actuality, the image signals of the reflection type light valves 2r, 2g, and 2b are used. Accordingly, the rotation angle of the polarization axis is changed.

  In order to improve the contrast of the image light incident on the light combining element 9, the polarizing plates 25 r, 25 g, 25 b for the respective colors are arranged between the reflective polarizing plates 8 r, 8 g, 8 b and the light combining element 9. preferable.

  The light combining element 9 has a function of combining each color light and emitting it to the projection optical system 10. The light combining element 9 has a dichroic film 9r formed on a red light reflecting surface and a dichroic film 9b formed on a blue light reflecting surface. For green light, dichroic films 9r and 9b are formed on the reflection surface of the light combining element 9 so that p-polarized light is mainly transmitted. Therefore, it is preferable to arrange a λ / 2 phase difference plate 26g for green light between the polarizing plate 25g and the photosynthetic element 9. By arranging the λ / 2 phase difference plate 26g for green light, the s-polarized light s1 becomes p-polarized light p1 and enters the light combining element 9, and the green light efficiently reaches the projection optical system 10. Become. In general, since the s-polarized light s1 has a higher reflectance than the p-polarized light p1, a λ / 2 phase difference plate for red light or a λ / 2 phase difference plate for blue light may not be provided. .

  By the way, in the present embodiment, as shown in FIG. 10, the reflective polarizing plates 8r, 8g, and 8b reflect the image light perpendicularly to the short axis (y direction) and enter the light combining element 9. Yes. For this reason, when image light is projected onto the screen in the state shown in FIG. 11 (installation state in which the yz plane is the bottom surface), a vertically long image is displayed on the screen. The reason for reflecting the image light perpendicular to the short axis is that when the image light is reflected perpendicular to the long axis (x direction), the back focus of the projection optical system 10 becomes long. Therefore, in order to display a desired image (horizontal rectangle), the projection type liquid crystal display device 1 shown in FIG. 11 is centered on the z axis so that the projection type liquid crystal display device 1 is in the installation state shown in FIG. It is necessary to rotate 90 degrees.

  Next, the relationship between the cross-sectional areas of the columnar optical elements 5r, 5g, 5b and the area (light incident area) of the main surface (light incident surface) of the reflective light valves 2r, 2g, 2b will be described. FIG. 12 is a diagram for explaining the relationship between the cross-sectional area of the columnar optical element and the light incident area of the reflective light valve. The relationship between the cross-sectional area of the columnar optical element 5g and the light incident area of the reflective light valve 2g is substantially the same as the relationship between the cross-sectional area of the columnar optical elements 5r and 5b and the light incident area of the reflective light valves 2r and 2b. Since these are the same, the relationship between the cross-sectional area of the columnar optical element 5g and the light incident area of the reflective light valve 2g will be described here. Here, a case where the effective incident angle to the reflective light valve 2g is about 14 degrees (F value of the illumination optical system is 2.1) will be described.

  12A to 12C show the optical path of green light from the reflective light valve 2g to the columnar optical element 5g. In the following description, it is assumed that the cross-sectional area of the columnar optical element 5g is S5 and the light incident area of the reflective light valve 2g is S2. The relay lens group 60g in the optical path of (a) shows the relay lens group 60g in the case of S5 = (S2) / 8. Further, the relay lens group 60g in the optical path of (b) shows the relay lens group 60g in the case of S5 = (S2) / 4. Further, the relay lens group 60g in the optical path of (b) shows the relay lens group 60g in the case of S5 = (S2) / 2.

The optical path (a) is not preferable because the imaging performance on the reflective light valve 2g is poor and the performance as an illumination optical system cannot be maintained. The optical path (b) and the optical path (c) have no problem in the imaging performance on the reflective light valve 2g. Therefore, when the area S5 of the cross section of the columnar optical element 5g that does not cause a problem in the imaging performance on the reflective light valve 2g is calculated, S5 = (S2) / 6. Therefore, the size of the columnar optical element 5g suitable for the imaging performance on the reflective light valve 2g can be expressed by the following equation (1). Equation (1) is the result when the F value of the illumination optical system is 2.1 or less. When the F value is greater than 2.1, the range of S5 is greater than the range of Equation (1). Become wider.
(S2) / 6 ≦ S5 ≦ (S2) / 2 (1)

  Note that when the area of the cross section of the columnar optical element 5g is increased, the diameter of the relay lens 6g3 is reduced, so that the relay lens group 6g can be easily designed. However, in order to make the light intensity uniform, There is a need to increase the length. For this reason, when aiming at size reduction of the projection type liquid crystal display device 1, it is preferable to make the area of the cross section of the columnar optical element 5g as small as possible. By reducing the area of the cross section of the columnar optical element 5g, the length of the columnar optical element 5g can be shortened.

  When the aperture of the relay lens 6g4 in the optical path (b) is compared with the aperture of the relay lens 6g4 in the optical path (c), the relay lens 6g4 in the optical path (c) is slightly larger. For this reason, it is preferable to reduce the area of the cross section of the columnar optical element 5g even when considering the interference of light beams in other optical paths by the relay lens 6g4.

In order to efficiently irradiate the light beam 2g emitted from the solid light source 3g, the area S3 of the solid light source 3g, the area S5 of the cross section of the columnar optical element 5g, and the area S2 of the reflective light valve 2g. The relationship of the following formula | equation (2) is preferable. The area S3 of the solid light source 3g, the area S5 of the cross section of the columnar optical element 5g, and the area S2 of the reflective light valve 2g may have a relationship other than the expression (2).
S5 = (((S2) / (S3)) ^ 0.5) × (S3) (2)

  As described above, the relay lens groups 60r, 60g, and 60b may be configured to have at least three relay lenses, and the configuration including four relay lenses is most preferable.

  In the present embodiment, the case where the condenser lens groups 4r, 4g, and 4b are configured by four condenser lenses has been described. However, the condenser lens groups 4r, 4g, and 4b each include three or less condenser lenses. You may comprise by a condensing lens and you may comprise by five or more condensing lenses. The condensing lens groups 4r, 4g, and 4b are most preferably composed of three condensing lenses. For example, when the condensing lens groups 4r, 4g, and 4b are configured by three condensing lenses, the second condensing lens side (the latter stage) of the first condensing lens (front condensing lens) The surface) is preferably an aspherical surface. The first condenser lens of the condenser lens groups 4r, 4g, 4b is preferably made of glass because it is close to the solid light sources 3r, 3g, 3b. Further, it may be configured such that the condensing lens groups 4r, 4g, 4b are not provided by arranging the columnar optical elements 5r, 5g, 5b in the subsequent stage (immediately after) of the solid light sources 3r, 3g, 3b. However, in that case, in order to efficiently guide the luminous flux to the reflection type light valves 2r, 2g, 2b, the cross-sectional areas of the columnar optical elements 5r, 5g, 5b are made substantially equal to the areas of the solid light sources 3r, 3g, 3b. Etc. are necessary.

  When the relay lens groups 60r, 60g, and 60b are manufactured so as to be shared (when the same relay lens is used as a relay lens for each color), it is preferable to use a glass material having a large Abbe number. Further, in order to configure each of the relay lens groups 60r, 60g, and 60b with four or less relay lenses, it is necessary to use a glass material having a high refractive index. For example, for the relay lens groups 60r, 60g, and 60b, a glass material having an Abbe number νd ≧ 45 or a glass material having a refractive index nd ≧ 1.7 is preferable.

  Although the case where the F value of the illumination optical system is 2.1 has been described in the present embodiment, the folding mirrors 7r, 7g, and 7b are relayed even when the F value is larger than 2.1. By disposing the lens groups 60r, 60g, and 60b between the relay lenses, the apparatus can be reduced in size.

  In the present embodiment, the relay lenses 6r1, 6r3, 6r4, the relay lenses 6g1, 6g3, 6g4, and the relay lenses 6b1, 6b3 are used in the case where three spherical lenses are used for each of the relay lens groups 60r, 60g, 60b. Although the case where 6b4 is used has been described, it is not limited to each of these three lenses, and any three of the relay lens groups 60r, 60g, 60b may be used.

  As described above, according to the embodiment, the projection type liquid crystal display device 1 has the folding mirrors 7r, 7g, and 7b arranged between the relay lenses of the relay lens groups 60r, 60g, and 60b. It becomes possible.

  Further, since a glass material with νd ≧ 45 or a glass material with a refractive index nd ≧ 1.7 is used, it is possible to use a relay lens manufactured in the same manner in any of the relay lens groups 60r, 60g, and 60b.

  The relationship between the cross-sectional area S5 of the columnar optical elements 5r, 5g, 5b and the light incident area of the reflection type light valves 2r, 2g, 2b with S2 is “(S2) / 6 ≦ S5 ≦ (S2) / 2”. Therefore, the imaging performance on the reflection type light valves 2r, 2g, 2b is improved.

  In addition, since a glass aspherical lens is used as the first condenser lens in each of the condenser lens groups 4r, 4g, and 4b, it is less susceptible to the heat generated from the solid light sources 3r, 3g, and 3b. Therefore, the multi-coating for reducing the interface reflection of the condenser lens is not peeled off by heat.

  As described above, the projection-type liquid crystal display device according to the present invention is suitable for image display using a solid-state light source that emits a single wavelength and a reflective light valve.

It is a figure which shows schematic structure of the projection type liquid crystal display device which concerns on embodiment of this invention. It is a figure which shows the structure at the time of seeing a projection type liquid crystal display device from x direction. It is a figure which shows the structure at the time of seeing a projection type liquid crystal display device from ay direction. It is a figure which shows the structure at the time of seeing a projection type liquid crystal display device from az direction. It is a figure for demonstrating operation | movement of a projection type liquid crystal display device. It is a figure for demonstrating the interference of a light ray, and the arrangement position of a relay lens. FIG. 6 is a diagram (1) for explaining the configuration of a relay lens group when three spherical lenses are used for the relay lens group. FIG. 6B is a diagram (2) for explaining the configuration of the relay lens group when three spherical lenses are used for the relay lens group. It is a figure (1) for demonstrating the dimension of a projection type liquid crystal display device. It is FIG. (2) for demonstrating the dimension of a projection type liquid crystal display device. It is a figure for demonstrating the polarized light on an optical path. It is a figure for demonstrating the relationship between the cross-sectional area of a columnar optical element, and the light-incidence area of a reflective light valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projection type liquid crystal display device 2r, 2g, 2b Reflection type light valve 3r, 3g, 3b Solid light source 4r, 4g, 4b Condensing lens group 5r, 5g, 5b Columnar optical element 6r1-6r4, 6g1-6g4, 6b1-6b4 Relay lens 7r, 7g, 7b Folding mirror 8r, 8g, 8b Reflective polarizing plate 9 Photosynthesis element 9r, 9b Dichroic film 10 Projection optical system 20g, 25r, 25g, 25b Polarizing plate 26g λ / 2 phase difference plate 50, 51 Body 60r, 60g, 60b Relay lens group

Claims (5)

In a projection type liquid crystal display device that displays an image by irradiating light of each color emitted from a plurality of solid light sources to a reflective light valve,
A columnar optical element that is disposed between optical paths from the solid-state light source to the reflective light valve and uniformizes the light intensity distribution of the light emitted from the solid-state light source;
A relay lens group having a plurality of relay lenses for guiding the light emitted from the columnar optical element to the reflective light valve;
A mirror disposed between the relay lenses of the relay lens group and bending the optical path of the light;
A projection type liquid crystal display device comprising: The relay lens group has four relay lenses,
2. The mirror according to claim 1, wherein the mirror is disposed between a relay lens through which light passes second in the optical path and a relay lens through which light passes third in the optical path. Projection type liquid crystal display device. Having three condensing lenses for condensing the light emitted from the solid light source onto the columnar optical element;
3. The projection type liquid crystal display device according to claim 1, wherein the condenser lens through which light passes first in the optical path is a glass aspheric lens.   The projection according to claim 1, wherein the relay lens includes a glass material having an Abbe number of 45 or more and a refractive index nd of 1.7 or more. Type liquid crystal display device.   The cross-sectional area of the columnar optical element is not less than one-sixth of the light incident area of the reflective light valve and not more than one-half of the light incident area of the reflective light valve. The projection type liquid crystal display device according to any one of claims 1 to 4.

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