JP2007199432A - Optical unit and projection display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical unit capable of attaining both high brightness and high contrast, and the miniaturization of the unit, and to provide a projection display device using the optical unit. <P>SOLUTION: A variable diaphragm for shielding light emitted from a light source and adjusting the light quantity of the emitted light is arranged between a first lens array for dividing the light from the light source into a plurality of luminous fluxes and a second lens array for superposing a plurality of secondary light source images formed by the first lens array in an area to be illuminated. Further, the surface of the variable diaphragm is formed to have a curved surface so as to reflect the shielded light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses an optical unit having an image display element that forms an optical image by modulating light intensity of light from a light source according to a video signal, and a projection lens that magnifies and projects the optical image, and the optical unit. The present invention relates to a projection display device.

  Patent Document 1 below discloses a configuration in which a variable aperture configured by a reflecting mirror is arranged on the light source side from the first array lens. Then, the light beam blocked by the variable diaphragm is reflected and returned to the light source side, and this return light beam is reflected and emitted again by the action of the parabolic reflector, so that the light beam originally discarded by the variable diaphragm is effectively used. Available technologies are disclosed.

Japanese Patent Laid-Open No. 2004-151474

  The variable aperture formed by the reflection mirror of Patent Document 1 cannot achieve high brightness unless the variable aperture is installed between the light source and the first lens array. It is necessary to newly secure an installation space and a space within the movable range thereof, and an increase in the size of the apparatus becomes a problem.

  The present invention has been made in view of the above-described conventional technical situation, and an object of the present invention is to achieve both high luminance and high contrast, an optical unit in which the apparatus is miniaturized, and a projection display device using the same. Is to provide.

  In one aspect of the present invention, a variable aperture that blocks and adjusts the amount of light emitted from a light source includes a first lens array that divides the light from the light source into a plurality of light beams, and a plurality of the first lens array. The secondary light source image is arranged between the second lens array for superimposing in the illuminated area, and the surface of the variable aperture has a curved surface that reflects the shielded light, The reflected light is returned to the light source, and the light is reused again by the reflector of the light source.

  According to the present invention, when the variable diaphragm that blocks and adjusts the amount of light emitted from the light source is disposed between the first lens array and the second lens array, the first lens array and the second lens array are arranged. Since the space between the lens arrays is sufficiently vacant, the variable aperture can be arranged using the space, so that the projection display device can be downsized.

  FIG. 1 is a diagram illustrating a projection display apparatus according to the first embodiment. In the same figure, the part surrounded by the alternate long and short dash line forms an optical image by modulating the light intensity of the light from the light source according to the video signal by the video display element, and enlarges and projects the optical image by the projection lens. In the optical unit, the projection type display device is one in which the optical unit is housed in a housing (not shown) together with a circuit board (not shown).

  In FIG. 1, light emitted from the light source 20 is incident on a lens array group 30 that equalizes light from the light source 20 including a first lens array 31 and a second lens array 32. In the first lens array 31 of the lens array group 30, a plurality of lens cells are arranged in a matrix, and the incident light is divided into a plurality of lights, and the second lens array 32 and the polarization conversion element 40 are efficiently divided. Lead to pass through. Similar to the first lens array 31, the second lens array 32 has a plurality of lens cells arranged in a matrix, and each lens cell is a projection of each lens cell of the corresponding first lens array 31. The image is displayed on each image display element (for example, a transmissive liquid crystal panel) 140R, 140G by a condenser lens 50, condenser lenses 110R, 110G, a first relay lens 80, a second relay lens 81, and a condenser lens 110B. Overlay on 140B. In this manner, the lens array group 30 makes the irradiation light to the image display element uniform. At this time, the light emitted from the second lens array 32 is aligned with polarized light in a predetermined direction (here, S-polarized light) by the polarization conversion element 40, and is color-separated by a color separation unit to be described later. The display elements 140R, 140G, and 140B are irradiated.

  Next, the color separation unit will be described. The light emitted from the condenser lens 50 is reflected by the first dichroic mirror 60, for example, the red light component (R light) is reflected, and enters the image display element 140R via the reflection mirror 70. The green-blue light component (GB light) transmitted through the first dichroic mirror 60 is incident on the second dichroic mirror 61, and for example, the green light component (G light) is reflected by the second dichroic mirror 61. Then, it enters the video display element 140G. The blue light component (B light) transmitted through the second dichroic mirror 61 is incident on the image display element 140B via the reflection mirrors 71 and 72 and the relay lenses 80 and 81. As shown in FIG. 1, since the optical path of the B light is longer than the optical paths of the R light and the G light, the image display element 140B is efficiently irradiated with the B light by the relay lenses 80 and 81.

  An incident-side polarizing plate 120G is disposed on the incident side of the G light image display element 140G, and P-polarized light components that have not been aligned with the S-polarized light by the polarization conversion element 40 are removed. The image display element 140G controls the voltage applied to the transparent electrode corresponding to each pixel of the image display element 140G according to the G image signal (not shown) by the element driving circuit 230, thereby reducing the amount of polarization twist. It is changing. An output side polarizing plate 130G is disposed on the output side of the image display element 140G, and the polarization direction is different from that of the incident side polarizing plate 120G by 90 °. For this reason, it is possible to transmit only the light that changes in the twist amount of polarization in each pixel and becomes P-polarized light through the output-side polarizing plate 130G. In this manner, an optical image is formed by performing light intensity modulation that changes the density (amount of polarization twist) on each pixel. As a result, the obtained optical image on the image display element 140G passes through the color synthesis dichroic prism 150 and is projected onto the screen 170 by the projection lens 160, so that a large screen image can be obtained.

  The video display elements 140R and 140B are formed in the same manner as the video display element 140G. However, in the image display elements 140 </ b> R and 140 </ b> B, in order for the transmitted light to be projected by the projection lens 160, it is necessary to reflect on the prism surface in the color synthesis dichroic prism 150. In this case, since the S-polarized light is more efficient, the λ / 2 plates 115R and 115B are arranged on the incident side of the incident-side polarizing plates 120R and 120B to convert the S-polarized light into P-polarized light. That is, the incident-side polarizing plates 120R and 120B act to remove the S-polarized light component, and only the light-polarized light that has been twisted into S-polarized light in each pixel of the image display elements 140R and 140B. The light passing through 130B is reflected by the prism surface in the color synthesis dichroic prism 150 and projected onto the screen 170 by the projection lens 160.

  Further, an IR cut filter 90 that cuts infrared rays is arranged in the R optical path, and a UV cut filter 100 that cuts ultraviolet rays is arranged in the B optical path.

  A variable diaphragm 10 is disposed between the first lens array 31 and the second lens array 32. The variable diaphragm 10 can be rotated by an electric rotation driving unit 180, and the rotation corresponds to a video mode corresponding to the viewing environment, and is controlled by the rotation driving circuit 210 via the electric rotation driving unit 180. The variable stop 10 has a reflection mirror 11 formed so that the incident angle of the light emitted from the light source 20 to the variable stop 10 is 90 degrees.

  FIG. 3A is a diagram showing the reuse of light reflected by the variable aperture 10, and FIG. 3B is an enlarged view around the variable aperture surrounded by a dotted line in FIG. 3A. . As shown in FIG. 3B, the variable stop 10 reflects the incident light 12, which is light from the first lens array, in a direction substantially the same as the direction of the light from the first lens array. The reflection mirror 11 is formed. The shape of the reflecting mirror 11 used in the present embodiment is a curved surface shape, in which light is reflected perpendicularly to the tangent line 14 of the curved surface. The curved surface may be formed in a circular shape, an elliptical shape, a parabolic shape, or the like. Therefore, the reflected light 13 reflected by the reflecting mirror 11 can be returned to the light source 20. The reflected light 13 is reflected again by the reflector 21 of the light source lamp and enters the first lens array 31 again, so that the light can be reused. In addition, although the reflector 21 used in Example 1 is formed in a parabolic shape, it goes without saying that it may be formed in an elliptical shape.

  FIG. 5 shows a case where the variable diaphragm 10 is operated (FIG. 5A) and a case where the variable diaphragm 10 is not operated (FIG. 5B). As shown in FIG. 5, when the variable diaphragm 10 is operated, the incident angle 140a to the image display element 140 is reduced and the contrast is improved as compared with the case where the variable diaphragm 10 is not operated. The reason is due to the incident angle characteristic of the video display element as can be seen from an example of the viewing angle characteristic of the contrast with respect to the incident angle to the general video display element 140 shown in FIG.

  Further, as shown in FIG. 4, the variable diaphragm 10 is arranged in a cell corresponding to each lens cell arranged in a matrix of the first lens array 31. This makes it possible to operate all or a part of each cell of the variable aperture 10, and when it is desired to enter light only in the central region having a high contrast as shown in FIG. If each cell is operated, a high contrast can be obtained. In addition, since the light can be reused by the reflecting mirror 11 formed on the variable stop, it is possible to improve the contrast without reducing the brightness. It is possible to achieve both high brightness and high contrast, which was a trade-off relationship.

  Here, the operation control of the variable diaphragm 10 will be described. The electric rotation drive unit 180 is driven by the rotation drive circuit 210, and this operation is controlled by the image adjustment unit 220. The image adjustment unit 220 operates each cell of the variable diaphragm 10 corresponding to the first lens array 31 from the rotation drive circuit 210 and the electric rotation drive unit 180 according to the image mode, and the incident angle to the image display element 140. Is variable.

  Returning to FIG. 1, the memory 310 is a memory for storing the operation state of each cell of the variable aperture 10 corresponding to each of the video modes (for example, the living mode and the theater mode) according to each viewing environment described above. . The memory 310 may store the operation state of each cell of the variable diaphragm 10 and the γ characteristics used in accordance with the viewing environment by a signal processing unit (not shown) in association with each other.

  The input unit 300 instructs the video adjustment unit 220 to select a video mode, and the video adjustment unit 220 selects the corresponding variable aperture from the memory 310 according to the video mode selected according to the viewing environment. The operation state and γ characteristic of each of the 10 cells are read out, the operation of each cell of the variable aperture 10 is controlled from the rotation drive circuit 210 and the electric rotation drive unit 180, and the γ characteristic corresponding to a signal processing unit (not shown) is set. . As described above, if the operation states and γ characteristics of the plurality of variable apertures 10 corresponding to various viewing environments are set in the memory 310 in advance corresponding to the respective video modes, the input made through the video adjustment unit 220 is performed. Only by selecting the video mode by the unit 300, a bright projected video having a contrast optimum for the viewing environment can be obtained.

  Of course, the viewer can store the optimum state of the variable aperture cell 10 corresponding to each viewing environment in the video adjustment unit 220 in the memory 310 corresponding to each viewing environment, and the input unit 300 can perform desired viewing. If the environment (video mode) is selected, the desired operation state of the variable aperture cell 10 may be easily reproduced.

  In the above, the video mode corresponds to the viewing environment. However, there are various genres in viewing video software, and the video characteristics differ depending on the genre. Therefore, it is preferable that the video characteristics can be selected corresponding to the genre as well as the viewing environment. That is, it is preferable to provide a video mode such as a television mode, a sports mode, and a music mode. In this way, a single projection display device having a video mode corresponding to the viewing environment and video genre can be realized.

  FIG. 6 shows the relationship between the brightness and the contrast with respect to the incident angle θ to the image display element 140 due to the action of the variable diaphragm 10. In the figure, the solid line represents experimental data representing the relationship between brightness and contrast when the variable aperture 10 operates, and the dotted line represents experimental data representing the relationship between brightness and contrast when the variable aperture 10 is not operated. As indicated by curves 250, 260, 270, and 280 indicated by solid lines in the figure, when the light incident angle θ to the image display element 140 is reduced by the operation of the variable aperture 10, the curve when the variable aperture 10 is not operated. Compared with 270 and 280, the contrast can be improved with almost no reduction in brightness.

  From the above, when the viewer selectively performs video adjustment according to the viewing environment in a bright room space such as a living room or a dark room space such as a dedicated room, the input unit 300 uses the video mode corresponding to the viewing environment (for example, If the theater mode or the living mode) is selected, the variable diaphragm 10 is rotated by the rotation driving circuit 210 and the electric rotation driving unit 180, and the incident angle of the light incident on the image display element 140 is changed. It is possible to obtain a bright projection image having a contrast optimum for the mode. In addition, since the variable stop 10 is disposed between the first lens array and the second lens array, it is possible to achieve both high brightness and high contrast and to reduce the size of the apparatus.

  In the first embodiment, the case where a transmissive liquid crystal panel is applied as an image display element has been described. Needless to say, the present invention can also be applied to a case where an image display element such as a reflective liquid crystal panel or a DMD panel is used. Yes.

1 is a diagram illustrating a projection display device according to Embodiment 1. FIG. The figure which shows the viewing angle characteristic of the contrast in a video display element. FIG. 5 is a diagram illustrating the operation of the variable aperture according to the first embodiment. FIG. 4 is an enlarged view of the periphery of a variable diaphragm surrounded by a dotted line in FIG. FIG. 3 is a diagram illustrating an arrangement of the variable diaphragm according to the first embodiment with respect to the lens array. Schematic which shows the incident angle to the image display element by a variable aperture. The figure which shows the change of the brightness and contrast with respect to the presence or absence of operation | movement of a variable aperture.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical unit, 10 ... Variable stop, 11 ... Reflection mirror, 12 ... Incident light, 13 ... Reflected light, 14 ... Tangent, 20 ... Light source, 21 ... Reflector, 30 ... Lens array group, 31 ... 1st lens array , 32 ... second lens array, 40 ... polarization conversion element, 50 ... condensing lens, 60 ... first dichroic mirror, 61 ... second dichroic mirror, 70, 71, 72 ... reflection mirror, 80 ... first Relay lens, 81 ... second relay lens, 90 ... IR cut filter, 100 ... UV cut filter, 110R, 110G, 110B ... condenser lens, 115R, 115B ... λ / 2 plate, 120R, 120G, 120B ... incident side Polarizing plate, 130R, 130G, 130B ... Emission side polarizing plate, 140R, 140G, 140B ... Image display element, 140a, 140b ... Incident angle to image display element, 150 ... color synthesis dichroic prism, 160 ... projection lens, 170 ... screen, 180 ... electric rotation drive unit, 210 ... rotation drive circuit, 220 ... image adjustment unit, 230 ... element drive circuit, 250 ... Curve of change in brightness with respect to incident angle on image display element when variable aperture is operated, 260 ... Curve of contrast change with respect to incident angle on image display element when variable aperture is operated, 270 ... Variable aperture Curve of change in brightness with respect to incident angle to image display element when not operating 280 ... Curve of contrast change with respect to incident angle to image display element without operating variable aperture, 300 ... Input unit, 310 ... memory.

Claims (10)

A light source;
A lens array group that is formed of a first lens array and a second lens array and uniformizes the illuminance of light from the light source;
It is disposed between the first lens array and the second lens array, and is formed so as to reflect the light from the first lens array in the same direction as the direction of the light from the first lens array. Variable aperture,
A video display element that modulates light from the second lens array based on a video signal to form an optical image;
A projection display device, comprising: a projection lens that projects light from the image display element. The projection display device according to claim 1,
The projection type display device, wherein the variable stop has a state in which light is stopped based on a shape of a viewing angle characteristic and a state in which the light is released. A projection display device according to claim 1 or 2,
The projection display device, wherein the variable diaphragm is a reflection mirror. A projection type display device according to claim 3,
A projection display device comprising a plurality of reflection mirrors. A projection type display device according to claim 4,
A projection-type display device, wherein the plurality of reflecting mirrors are arranged so as to have a shape based on a viewing angle characteristic when the variable aperture is in a narrowed state. The projection display device according to claim 3, wherein
The projection display device, wherein the reflection mirror is formed of a curved surface. The projection display device according to claim 6,
The projection display device characterized in that the curved surface has any one of a circular shape, an elliptical shape, and a parabolic shape. The projection display device according to claim 6 or 7,
The variable aperture diaphragm reflects light from the first lens array perpendicularly to a tangent to the curved surface. A light source;
A lens array group that is formed of a first lens array and a second lens array and uniformizes the illuminance of light from the light source;
A variable stop disposed between the first lens array and the second lens array and formed of a curved surface that reflects light from the first lens array;
A video display element that modulates light from the second lens array based on a video signal to form an optical image;
A projection lens for projecting light from the image display element;
The projection display apparatus, wherein light from the first lens array is reflected perpendicularly to a tangent to the curved surface. An optical unit for a projection display device that irradiates a video display element with light from a light source and modulates the light based on a video signal to form an optical image,
A lens array group formed of at least a first lens array and a second lens array and uniformizing the illuminance of light from the light source;
It is arranged between the first lens array and the second lens array, and is formed so as to reflect the light from the first lens array in the same direction as the light from the first lens array. And an optical unit.

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