JP2007065519A - Projection image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection image display device which improves contrast performance, by reducing the quantity of light and reducing the angle of incidence on a transmissive liquid crystal panel. <P>SOLUTION: The projection image display device has a light-shielding unit wherein second openings, having areas smaller than a plurality of incidence areas on the incidence faces of deflection conversion elements arrayed at prescribed intervals are arrayed between a plurality of first openings which are disposed at the same prescribed intervals as the incidence areas and have shapes that correspond to the incidence faces of the deflection conversion elements. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display apparatus using an image display element such as a liquid crystal panel.

  Conventionally, in a projection display apparatus such as a liquid crystal projector, for example, when projecting an image with a small size or projecting an image with many dark scenes such as a movie, more light than necessary is projected on the screen. There was a problem that it was too difficult to see the video. In order to deal with this problem, in the above case, a technique for reducing the amount of light projected on the screen by reducing the amount of light incident on the flat plate type polarization conversion element with a light shielding plate is disclosed in JP-A-2002-23106. It is described in. In this technique, the amount of light projected on the screen can be reduced by reducing the amount of light incident on the flat-plate polarization conversion element by reducing the amount of light with a light shielding plate.

Japanese Patent Laid-Open No. 2002-23106

  However, in the technology disclosed in the above document, no consideration is given to contrast. Since the amount of light incident on the flat plate polarization conversion element is simply reduced, the contrast performance hardly changes, but the difference between the brightness for bright images and the brightness for dark images becomes small. The difference in tone is also reduced. Therefore, there is a problem that the difference in gradation cannot be determined particularly in a dark image.

  In the projection display apparatus, the first openings are arranged at the same predetermined intervals as the plurality of incident areas on the incident surfaces of the deflection conversion elements arranged at predetermined intervals, and correspond to the incident surfaces of the deflection conversion elements. A light-shielding unit in which second openings having an area smaller than the plurality of incident regions are arranged between the plurality of first openings having a shape.

  According to the present invention, since the contrast performance is improved when the amount of light is reduced, it is possible to provide a high-quality projection display apparatus even when the amount of light is reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of an illumination optical system of a projection display apparatus equipped with the present invention. In FIG. 1, 1 is a light source, 5 is a reflector that reflects light from the light source 1 on a reflecting surface such as an ellipsoid or a paraboloid, and 6 has a plurality of small lens cells arranged in a matrix. A first array lens for forming a secondary light source image, 7 has a plurality of small lens cells arranged in a matrix conjugate to the individual lens cells of the first array lens 6, and the individual lens images of the first array lens. , 191 and 192 are light shielding plates, 8 is a flat plate type polarization conversion element that aligns light from the second array lens 7 side with polarized light in a predetermined direction, 20 is a condensing lens, 9R, 9G and 15 are condenser lenses, 4 and 11 are dichroic mirrors for color separation, 12, 17 and 18 are mirrors that change the optical path direction by reflection, and 13 and 14 are a first relay lens and a second relay lens, respectively. , 2R, 2G, 2B are respectively the colors transmissive liquid crystal panel, the synthesizing prism for color synthesis 10, the projection lens unit for magnified projection 3, 16 is a screen.

  The optical system from the first array lens 6 to the condenser lenses 9R, 9G, 15 constitutes an illumination optical system for the transmissive liquid crystal panels 2R, 2G, 2B. In the transmissive liquid crystal panels 2R, 2G, and 2B, a video signal driving circuit (not shown) modulates the light intensity according to the video signal with respect to the light from the light source 1, thereby forming an optical image.

  In the configuration of FIG. 1, the light beam emitted from the light source 1 is collected by being reflected by the reflector 5 and emitted to the first array lens 6 side. The first array lens 6 divides an incident light beam into a plurality of light beams by a plurality of lens cells so that the light beam can efficiently pass through the second array lens 7 and the polarization conversion element 8. Each of the plurality of lens cells projects the lens image of the lens cell of the corresponding first array lens 6 on the transmissive liquid crystal panels 2R, 2G, and 2B side. At this time, the flat polarization conversion element 8 aligns the light beam from the second array lens 7 with polarized light in a predetermined direction (here, S-polarized light) as described above. The detailed configuration of the flat plate type polarization conversion element 8 will be described later. The condensing lens 20, the condenser lenses 9R, 9G, and 15, the first relay lens 13, and the second relay lens 14 convert the lens image of each lens cell of the first array lens 6 into a transmissive liquid crystal panel 2R of each color. 2G, 2B.

  The white light emitted from the light source 1 is emitted from the flat plate type polarization conversion element 8, and displays each image through the condenser lens 20, the first relay lens 13, the second relay lens 14, and the condenser lenses 9 R, 9 G, and 15. In the process of irradiating the elements 2R, 2G, and 2B, the dichroic mirrors 4 and 11 separate the red light (R light), the green light (G light), and the blue light (B light), respectively. The panel 2R, 2G, 2B is irradiated. In the case of the example of FIG. 1, the dichroic mirror 4 has a characteristic of transmitting green light and blue light and reflecting red light, and the dichroic mirror 11 is a characteristic of reflecting green light and transmitting blue light. Have The transmissive liquid crystal panels 2R, 2G, and 2B irradiated with each color light modulate each color light with an external video signal to form an optical image corresponding to the video signal, and emit the signal light to the synthesis prism 10 side. . In the combining prism 10, the signal lights of the respective color lights are color combined and emitted to the projection lens unit 3 side. The projection lens unit 3 enlarges and projects an optical image of white light on the screen 16 and displays an image. The first relay lens 13 and the second relay lens 14 have an effect of compensating for the optical path length of the image display element 2B with respect to the optical path lengths of the transmissive liquid crystal panels 2R and 2G. Further, the condenser lenses 15, 9R, 9G suppress the spread of the light flux after passing through the transmissive liquid crystal panels 2R, 2G, 2B, and enable the projection lens unit 3 to perform efficient enlargement projection.

  FIG. 2 is an explanatory view of a part of the flat-plate polarization conversion element section as viewed from above. As shown in the drawing, the flat polarization conversion element 8 has a plurality of translucent members 84 bonded together, and reflection films 82 and polarization separation films 83 are alternately formed on the bonded surfaces. Therefore, on the incident surface on the second lens array 7 side of the plate-type deflection conversion element 8, the bonding surfaces of the plurality of translucent members 84 are arranged at a constant interval (pitch) d in the x direction. Therefore, as for the incident area of the flat type deflection converting element 8, the rectangular incident areas having the width d are arranged in the x direction at a constant interval d. A λ / 2 phase difference plate 81 is disposed on a part of the exit surface of the flat plate type polarization conversion element 8. The two light shielding plates 191 and 192 are arranged between the flat-plate-type polarization conversion element 8 and the second lens array 7, and the light transmitted through the second lens array 7 (S-polarized light + P-polarized light) is transmitted through the light shielding plates 191 and 192. The light passes through the openings 191 a and 192 a and enters the flat-plate polarization conversion element 8.

  Of the light incident on the flat polarization conversion element 8, P-polarized light is transmitted through the polarization separation film 83, and is transmitted through the λ / 2 phase difference plate 81 and becomes S-polarized light when emitted from the flat polarization conversion element 8. . The S-polarized light incident on the flat-plate polarization conversion element 8 is reflected by the polarization separation film 83, and then reflected by the reflection surface 82 in the same direction as the P-polarization transmitted through the polarization separation film 83 to cause the flat-plate polarization conversion element 8 to pass. Exit. As described above, the light emitted from the plate-type polarization conversion element 8 is aligned with the S-polarized light. At this time, the light shielding plates 191 and 192 shield the light emitted from the flat-plate polarization conversion element 8 so as not to directly enter the reflection film 82.

  Next, the light shielding plates 191 and 192 will be described. FIG. 3 is a front view of the first light shielding plate 191. As shown in the drawing, a hole (opening) 191a is provided, and the remaining portion is a light shielding portion 191b (shaded portion). FIG. 4 is a front view of the second light shielding plate 192. A hole (opening) 192a is provided, and the remaining portion is a light shielding portion 192b (shaded portion). As shown in each figure, the shapes of the openings 191a and 192a are different, and two light shielding plates 191 and 192 are used in an overlapping manner.

  In this example, the shape of the second light shielding plate 192 is such that, with respect to the x direction, the opening 192a and the light shielding portion have the same distance d as the pitch of the bonding surfaces of the translucent member 84 on the incident surface of the flat plate deflection transducer 8. 192b is arranged. Further, the opening 192a of the second light shielding plate 192 has the same height as the effective incident width in the y direction of the flat plate deflection conversion element 8 in the y direction.

  On the other hand, the first light-shielding plate 191 has the same shape as the second light-shielding plate 192, and further, the opening 191a-a used at the time of diaphragm is made a part of the region corresponding to the light-shielding portion 192b of the second light-shielding plate 192. It has a formed shape. The openings 191a-n used during normal use have the same shape as the openings 192a of the second light shielding plate 102. The opening 191a-a used at the time of diaphragm is a portion of 192b arranged at the same interval d as the pitch of the bonding surface of the translucent member 84 on the incident surface of the flat plate type deflection conversion element 8 in the second light shielding plate 192. On the other hand, it is formed as an opening whose height in the y direction is changed from the central portion. As described above, the height in the y direction is high near the center in the x direction, and is lower as the distance is 191a-a arranged outward from the center. Due to this difference in height, when the center of the light shielding plate is the optical axis of the illumination optical system, it can be formed into a substantially circular shape centered on the optical axis.

  4 and FIG. 5 show that two light shielding plates having openings of different shapes are arranged on the incident side of the flat plate type polarization conversion element, so that these two light shielding plates are overlapped in a normal state. The opening shape to be formed is a slit-like shape that is equivalent to the pitch interval of the plate-type polarization conversion element. Further, the outer shape of the opening when one of the two light shielding plates is moved by one pitch of the flat plate-type polarization conversion element is a substantially circular shape centered on the optical axis.

  FIG. 5 is a diagram showing a state in which two light shielding plates 191 and 192 are overlapped. FIG. 5A shows the state of the light shielding plates 191 and 192 during normal use. As shown in the figure, light shielding portions 19b constituted by light shielding portions 191b and 192b of light shielding plates 191 and 192 and openings 19a constituted by openings 191a and 192a of the light shielding plates 191 and 192 are alternately arranged, The light from the second lens array 7 is transmitted. Thus, in the normal state, the opening 191a-n of the first light shielding plate 191 and the opening 192a of the second light shielding plate 192 overlap, and the opening 191a-a of the first light shielding plate 191 It overlaps with the light shielding part 192b of the plate 192.

  FIG. 5B shows a state where the amount of light is reduced. In the state shown in FIG. 5A, the first light-shielding plate 191 is moved in the arrow direction in the y direction, so that the state shown in FIG. The shape of the opening 19a at this time is a substantially circular shape (broken line) whose outer shape is centered on the optical axis. That is, in the narrowed state, the opening 191a-n of the first light shielding plate 191 overlaps the light shielding portion 192b of the second light shielding plate 192, and the opening 191a-a of the first light shielding plate 191 is the opening of the second light shielding plate 192. It overlaps with the portion 192a. Therefore, a substantially circular opening can be formed as a whole from the shape of the opening 191a-a.

  Next, the operation of the light shielding plate will be described.

  FIG. 6 is a schematic diagram of a CC cross section when the light shielding plates 191 and 192 are in the normal state of FIG. As shown in the figure, all the light transmitted through the second lens array 7 is transmitted through the openings of the light shielding plates 191 and 192, is incident on the flat plate-type deflection conversion element 8, and is transmitted through the condensing lens 20 to the transmissive liquid crystal panel. 2 is irradiated. The incident angle at this time is 22a and the optical axis is 21.

  FIG. 7 is a schematic diagram of a CC cross section when the light shielding plates 191 and 192 are in the narrowed state of FIG. As shown in the drawing, the light at the outermost peripheral portion of the light transmitted through the second lens array 7 is shielded by the light shielding portion of the first light shielding plate 191 and does not enter the flat plate type deflection conversion element 8. Accordingly, the amount of light applied to the transmissive liquid crystal panel 2 is reduced by the amount of light shielded, and the incident angle to the transmissive liquid crystal panel 2 is smaller than the incident angle 22a in the normal state as shown in 22b.

  In this embodiment, the light shielding plates 192 and 192 are provided. However, for example, the light shielding plate 192 may be bonded to the incident surface of the deflection conversion element in advance. In this case, the first light shielding plate 192 may be disposed not on the light source 1 and the flat plate deflection conversion element 8 but on the downstream side of the flat plate deflection conversion element 8 as viewed from the light source 1.

  FIG. 8 is a diagram showing the relationship between the incident angle (tilt angle) and contrast performance in a transmissive liquid crystal panel. As shown in the figure, when the incident angle is small, the contrast performance is improved. Therefore, when the amount of light is reduced by the light shielding plates 191 and 192 (FIG. 5B), the amount of light decreases and the angle of incidence on the transmissive liquid crystal panel 2 decreases, so that the contrast performance increases. Therefore, since the contrast performance is improved in a state where the light amount is reduced by the light shielding plate, a high-quality image can be obtained even in the case of a dark image.

  In addition to reducing the amount of light, the incident angle of light incident on the transmissive liquid crystal panel or the like was reduced. Accordingly, when the amount of light is reduced, the angle of the light incident on the transmissive liquid crystal panel is reduced, so that the contrast performance is improved.

  Next, another embodiment will be described with reference to FIG. In the present embodiment, the first light-shielding plate 191 and the second light-shielding plate 192 have openings 191a-a and 192a-a at the time of diaphragm, respectively. For example, as shown in FIG. 9A, the first light shielding plate 191 is formed with an opening 191a-a that is half the width of the opening 19a at the time of aperture on the left side of the normal opening 191a-n. Yes. In addition, as shown in FIG. 9B, the second light shielding plate 192 has an opening 192a-a that is half the width of the opening 19a at the time of the aperture on the right side of the opening 192a-n at the normal time. .

  FIG. 9C shows a configuration in which the first light shielding plate 191 and the second light shielding plate 192 are stacked in a normal state. In the present embodiment, in the normal state, when the two light shielding plates 191 and 192 are completely overlapped, an opening corresponding to the pitch of the flat plate deflection conversion element 8 is formed. On the other hand, as shown in FIG. 9 (D), in the aperture state, for example, the second light shielding plate is moved by one pitch in the direction indicated by the arrow in FIG. 9 (C) to form a substantially circular opening 19a. To do. In the case of the present embodiment, since the shapes of the first light shielding plate 191 and the second light shielding plate are line symmetric with respect to the y axis, the manufacturing process can be made common. In the example of FIG. 9, one light shielding plate is moved. However, both light shielding plates may be moved in opposite directions by 1/2 pitch. In this way, it is possible to cause a shift between the position of the optical axis center in the normal state and the position of the optical axis center in the aperture state.

The embodiment of the present invention has been described as follows.
(1) Projection-type image display apparatus that irradiates light from a light source unit composed of a light source and a reflector onto an image display element by an illumination optical system, forms an optical image corresponding to the image signal, and magnifies and projects the image. And having a plurality of slits equivalent to the pitch interval of the plate polarization conversion element, and having a circular transmitted light area smaller than the total light flux region transmitting through the slit in the slit shape, and in the vicinity of the plate polarization conversion element The projection type image display device forms a diaphragm by blocking the outermost light region by changing the pitch of the flat plate polarization conversion element by 1 pitch to the left and right in the vicinity of the light shielding plate.

  (2) In addition to the projection type image device of (1), the left and right are means having an aperture state that can vary the pitch of the flat plate polarization conversion element by one pitch, and there are variable positions of the light shielding plate at two or more locations. This is a projection type image display apparatus in which the aperture amount of the light beam is different at the position of the light shielding plate.

  (3) In addition to (1) or (2), a means having a diaphragm state in which the pitch of the flat-plate polarization conversion element is variable on the left and right, and a light-shielding plate having variable positions at two or more locations on the lamp side. This is a projection display apparatus installed in front of a certain plate polarization conversion element.

  (4) In addition to (1) or (2), means having a diaphragm state in which the flat-polarized light conversion element is variable by one pitch on the left and right sides, and a light-shielding plate having variable positions at two or more positions is viewed from the lamp. And a projection display device installed after the flat plate polarization conversion element.

It is a block diagram of the illumination optical system of the projection type video display apparatus carrying this invention. It is explanatory drawing of a flat type polarization conversion element part. It is a front view of a 1st light-shielding plate. It is a front view of a 2nd light shielding plate. It is explanatory drawing of the state which accumulated the 1st light shielding plate and the 2nd light shielding plate. It is a schematic diagram of a light shielding plate in a normal state. It is a schematic diagram of the state which narrowed down the light quantity with the light-shielding plate. It is a figure which shows the relationship between an incident angle (tilt angle) and contrast performance. It is explanatory drawing of the 1st light-shielding plate and 2nd light-shielding plate of another example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source 2, 2R, 2G, 2B ... Video display element 3 ... Projection lens unit 12, 17, 18 ... Mirror, 5 ... Reflector, 6 ... 1st array lens, 7 ... 2nd array lens, 8 ... Polarization conversion element, 20 ... condensing lens, 9R, 9G, 15 ... condenser lens, 10 ... synthetic prism, 4, 11 ... dichroic mirror, 13 ... first relay lens, 14 ... second relay lens, 16 ... screen, 191 ... 1st light shielding plate, 192 ... 2nd light shielding plate, 22a, 22b ... Light beam incident angle.

Claims (4)

A light source;
A deflection conversion element having an incident surface in which a plurality of incident regions for incident light emitted from the light source are arranged at predetermined intervals, and an emission surface that emits the incident light in alignment with the first deflected light;
A plurality of first openings having the same shape as each of the plurality of incident areas are arranged at the predetermined interval, and are second openings having a width of the predetermined interval and smaller than the plurality of incident areas. A light-shielding unit in which second openings having an area are alternately arranged with the plurality of first openings at the predetermined interval;
An image display element for modulating the deflected light in accordance with an image signal;
A projection-type image display device having a projection device that projects modulated light. The projection-type image display device according to claim 1,
The shading unit is
A plurality of first openings having the same shape as the plurality of incident areas are arranged at the predetermined interval, and the plurality of first openings are second openings having the predetermined interval width alternately. A first shielding plate in which second openings having an area smaller than the incident area of the first shielding plate are arranged at the predetermined interval, and slidable in the arranged direction with respect to the deflection conversion element When,
A projection display apparatus comprising a second shielding plate in which a plurality of openings having the same shape as the plurality of incident areas are arranged at the predetermined interval. The projection-type image display device according to claim 1 or 2,
A projection-type image display apparatus, wherein the height of each of the plurality of second openings is lowered stepwise in order of arrangement from the center of the optical axis of light transmitted through the light shielding unit toward the outside. The projection-type image display device according to claim 2,
At least the second light-shielding plate is disposed between the light source and the deflection conversion element.

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