JP2005017810A - Projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that the higher brightness is hardly realized in a fixed type diaphragm, the high speed response can not be attained in a movable type diaphragm and, further in the movable type one, a diaphragm plate remains inserted due to a failure of a drive circuit, in the fixed type and movable type diaphragms which are disposed in an optical path of an illumination optical system of the conventional projection type display device and opening shapes of which are non-circular. <P>SOLUTION: The projection type display device is provided with the diaphragm plate which can shield one part of a luminous flux and can be driven by a voice coil motor and an arm which is held by an electromagnet on a position independent of a drive mechanism during the operation and is energized in one direction where the diaphragm plate is retained in the state withdrawn from the optical path because the energizing to the electromagnet is interrupted when the failure etc. of the drive circuit occurs. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a mirror array element that can be modulated for each pixel or a liquid crystal panel as a reflective or transmissive light valve, a light source that irradiates light to the light valve, and a light valve that reflects or transmits light. The present invention relates to a projection display device that includes a projection lens that enlarges and projects a light beam modulated for each pixel onto a screen and is provided with a movable diaphragm plate that blocks part or all of the light beam from a light source.
[0002]
[Prior art]
Conventionally, in this type of projection display device, a method described in Patent Document 1 is known as a method for realizing a high contrast ratio without reducing luminance as much as possible.
[0003]
FIG. 6 illustrates an example of an asymmetric aperture that can increase the brightness without degrading the contrast ratio in the conventional projection display device of this type. In the figure, the mirror array element 101 has as many micromirrors 102 as the number of pixels, and the micromirrors 102 can rotate at a predetermined angle with respect to the rotation shaft 103. The illumination light that illuminates the mirror array element 101 has an asymmetric aperture shape indicated by an aperture shape 104. Specific implementation methods include a method of installing a diaphragm having a predetermined shape in an optical path of an illumination optical system that irradiates light to a mirror array, and a method using a distortion image lens as a constituent lens. In addition, a movable diaphragm that blocks a part of the light flux in the illumination optical path is provided, and a drive motor is used according to the type of video (for example, presentation images from a personal computer, movies, etc.) and the intensity of external light. A technique is known in which the insertion amount of the diaphragm plate is adjusted to achieve both high luminance and a high contrast ratio.
[0004]
[Patent Document 1]
Japanese National Patent Publication No. 9-500738
[Problems to be solved by the invention]
However, in the above-described example of the fixed asymmetric opening of the conventional method, although the contrast ratio can be improved, the luminance is unavoidably reduced as compared with the circular opening shape. Also, for those using a drive motor, there is no problem with switching at a relatively low speed, such as the user selecting and adjusting according to his / her preference, but it is difficult to respond to sudden changes in the image from the viewpoint of response speed. It had the problem of being. Also, if a drive device failure or drive circuit failure occurs with the diaphragm plate inserted in the optical path, it will stop as it is, leaving no brightness, and the diaphragm plate will be placed in the optical path. In order to evacuate from the service, there is a further problem that it is necessary for the service person to disassemble and deal with it.
[0006]
The present invention solves the above-described problems, and determines the amount of blocking the illumination light beam based on the input information, and accordingly, a diaphragm plate that enables high-speed driving of the diaphragm plate that blocks the illumination light beam. It has a drive mechanism and has a means to retract the diaphragm plate from the optical path when a drive device failure or drive circuit failure occurs with the diaphragm plate inserted in the optical path. An object of the present invention is to provide a projection display device capable of maintaining the state.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the projection display device of the present invention includes a light valve that can be modulated for each pixel according to input information, a light source that emits light to irradiate the light valve, and light emitted from the light source. An illumination optical system composed of a plurality of optical elements for condensing light and irradiating the light valve, a projection lens for projecting reflected or transmitted light from the light valve, and an illumination optical system positioned in the illumination optical system. A diaphragm plate that can be moved to a position where it is blocked or not blocked, a voice coil motor that moves the diaphragm plate between a position where it blocks a part of the light beam, and a position where it is not blocked, and detection that can detect the position of the diaphragm plate Means. Furthermore, urging means that can move the diaphragm plate to a position that does not block the light beam, and holding means that can hold the urging means at a position where the urging means does not act on the diaphragm plate are provided. Based on the input information, the amount of the illumination light beam is determined, and the diaphragm plate is driven at a high speed accordingly.If the diaphragm plate is inserted in the optical path, the drive device malfunctions or the drive circuit By having means for retracting the aperture plate from the optical path when a failure occurs, a high luminance state can be maintained even if it is continuously used.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0009]
(Embodiment 1)
FIG. 1 is a front view showing a diaphragm plate driving mechanism 1 which is a main part of an embodiment of the projection display device of the present invention. FIG. 2 is a plan view showing the whole projection display device including the diaphragm plate driving mechanism 1. FIG. A lamp 2 as a light source, an ellipsoidal mirror 3 that condenses the light, a color wheel device 4 that is constituted by a filter that selectively transmits red, green, and blue light, and is rotated by a drive motor; A condenser lens 6, a first lens array 7, and a second lens array 8 as an illumination optical system 5 that converts a light beam having a predetermined divergence angle transmitted through the color wheel device 4 into parallel light and focuses and irradiates the light valve. , A folding mirror 9, a field lens 10, a TIR prism 11 that reflects the light beam from the illumination optical system 5 to the light valve side and transmits the reflected light from the light valve straight, and a mirror array element 12 as a light valve, The projection lens 13 is configured to enlarge and project the light reflected in a predetermined direction by the mirror array element onto a screen or the like outside the apparatus. In the mirror array element 12, as shown in FIG. 3, the micromirrors 14 and their rotating shafts 15 are regularly arranged, and the micromirrors of only the pixels to be turned on in the luminous flux are rotated in the incident direction of light from an oblique direction. The reflected light is reflected in the direction that can be projected by the projection lens 13, and the micro mirror corresponding to the pixel to be turned off is rotated in the opposite direction so that the reflected light is reflected in the direction that is projected by the projection lens 13. The mirror array element acts as a light valve. In addition, an aperture plate driving mechanism 1 having an aperture plate 16 that blocks illumination light from one direction to an arbitrary position is provided in the vicinity of the lamp side of the second lens array (a position conjugate with the aperture position of the projection lens 12). The drive system is in the form of a voice coil motor (hereinafter referred to as VCM), the details of which are shown in FIG. 1. The movable plate has a diaphragm plate 16 and a diaphragm plate 16 attached to the movable side, and a rotatable actuator hub 17 and its actuator. A coil 18 and a sensor plate 19 for detecting the rotation angle of the actuator hub 17 are integrally attached to the hub 17. On the fixed side, a high-temperature magnet 20, a yoke 21 to which the magnet 20 is attached, a yoke 22 provided on the opposite side across the coil 18, a pivot shaft 23 of the actuator hub 17, and a sensor plate 19 The reflection sensor 24 can detect the rotation angle of the actuator hub 17 based on the reflected light. Further, an arm 27 having an iron core 26 fixed at a predetermined position is rotatably attached to the rotation support shaft 23 and is fixed to the fixed yoke 21. A tension spring 28 is stretched between them and is always urged in the direction of arrow A. Further, an electromagnet 29 is provided on the fixed side, which can be attracted against the urging force of the tension spring 28 when the iron core 26 of the arm 27 comes into contact or comes close to the fixed side. Details are shown in FIG.
[0010]
The diaphragm plate driving mechanism 1 described above is known to have a high temperature of 100 ° C. or higher because the diaphragm plate 16 directly blocks the illumination light, and the VCM components to be used can withstand use in a high temperature environment. There is a need. For example, for the magnet 20, a salalium cobalt magnet, an alnico magnet, or the like is used, and for the coil 18, for example, a polyimide imide copper wire is used as a winding that can withstand high temperature use.
[0011]
The operation of the projection display apparatus configured as described above will be described below. As a basic optical operation, the white light from the lamp 2 is condensed by the ellipsoidal mirror 3 to form a spot shape, and is irradiated to the color wheel device 4. The color wheel device 4 includes a rotating filter and transmits red, green, and blue light in a time-sharing manner. This light beam is converted into parallel light by the action of the condenser lens 6, and the surface of the mirror array element 12 is uniformly illuminated by the action of the first lens array 7 and the second lens array 8. In this mirror array element 12, by rotating a micro mirror according to input information, a full color image can be projected by projecting each color image through a projection lens 13 at a predetermined timing onto an external screen. I can do it.
[0012]
Next, the operation of the diaphragm drive mechanism 1 arranged in the middle of the illumination optical system will be described with reference to FIG. The basic structure of the diaphragm drive mechanism 1 is a VMC, and a coil 18 in a magnetic field formed by a magnet 20 and yokes 21 and 22 is energized from a drive circuit (not shown) to rotate the actuator hub 17 around the rotation support shaft 23. It is possible to operate at a high speed by generating the moment. In actual use, it is used in the state shown in FIG. 4 (d). In this state, the brightness component of the projected image is extracted from the video signal. In a bright scene, the diaphragm plate 16 is in a position where it is retracted from the illumination light path, or dark. In the scene, the position is controlled to block the illumination light path. This is realized by detecting the angle of the actuator hub 17 by using the reflective sensor 24 and the sensor plate 19 attached to the VCM, and performing high-speed position control by a servo circuit.
[0013]
Next, a description will be given of a case where a circuit has failed at power ON / OFF. When the power is turned off, it is urged in the direction of arrow A by the urging force of the tension spring 28 in the state shown in FIG. After the operation is started, the arm 27 is rotated in the arrow B direction by the engaging portion 25 of the actuator hub 17 by the VMC, and the state shown in FIG. At this time, the iron core 26 of the arm 27 is attracted by energizing the electromagnet 29. Thereafter, the urging force of the tension spring 28 does not act on the actuator hub 17 in the state of FIG. If the drive circuit fails for some reason during use, the circuit is cut off from conduction to the electromagnet 29 so that the attraction force of the electromagnet 29 is lost and the iron core 26 of the arm 27 is opened. 27 rotates in the direction of arrow A, moves in a state where the engaging portion 25 of the actuator hub 17 is hooked on the way, and becomes the state of FIG. 4A again. In addition, the 1st position described in the claim means the position which interrupts a part of light beam like the position of FIG.4 (c), for example.
[0014]
The second position refers to a position that does not block the light beam, such as the position shown in FIG.
[0015]
In this way, by configuring the diaphragm plate so as to be able to rotate at high speed, the amount of shielding the illumination light beam 30 is determined based on the input information so that the contrast and the brightness are optimized, and the diaphragm plate 16 is driven accordingly. It becomes possible to do. Further, even if the drive circuit breaks down with the diaphragm plate 16 inserted in the illumination light beam 30, the diaphragm plate 16 can be quickly retracted so as not to block the illumination light beam 30. Further, the diaphragm plate 16 is fixed in one direction even during transportation, which is very useful.
[0016]
In the above description, the method using one mirror array element has been described. However, the present invention can be similarly applied to a method using a plurality of mirror array elements.
[0017]
【The invention's effect】
As described above, according to the present invention, a part of the light beam can be blocked at a predetermined position in the illumination optical path of the projection display apparatus, and the blocking amount can be changed at high speed. As a result, it is possible to obtain a remarkable effect that the image quality can be changed at high speed with emphasis on luminance or contrast ratio depending on input information or user preference. In addition, if a drive circuit failure occurs during use, it is possible to quickly retreat to a position where the aperture plate does not block the optical path, and it is possible to continue projecting high-intensity images even if it is used continuously. An effect is also obtained.
[Brief description of the drawings]
FIG. 1 is a front view of a diaphragm drive mechanism according to an embodiment of the present invention. FIG. 2 is a plan view showing a configuration of an entire projection display apparatus. FIG. 3 is a diagram showing a structure of a mirror array element. FIG. 5 is a perspective view showing details of the engaging portion of the actuator hub. FIG. 6 is a view of a fixed aperture shape with respect to a conventional mirror array element.
DESCRIPTION OF SYMBOLS 1 Diaphragm drive mechanism 2 Lamp 3 Ellipsoidal mirror 4 Color wheel apparatus 5 Illumination optical system 6 Condenser lens 7 1st lens array 8 2nd lens array 9 Folding mirror 10 Field lens 11 TIR prism 12 Mirror array element 13 Projection lens 14 Minute Mirror 15 Rotating shaft 16 Diaphragm plate 17 Actuator hub 18 Coil 19 Sensor plate 20 Magnets 21 and 22 Yoke 23 Rotating spindle 24 Reflective sensor 25 Engaging portion 26 Iron core 27 Arm 28 Pulling spring 29 Electromagnet 30 Illumination beam 101 Mirror array Element 102 Micromirror 103 Rotating shaft 104 Opening shape

Claims (5)

A light valve that can be modulated for each pixel according to the input information,
A light source that emits light to irradiate the light valve;
An illumination optical system comprising a plurality of optical elements that collect light emitted from the light source and irradiate the light valve;
A projection lens for projecting reflected or transmitted light of the light valve;
A first plate located in the illumination optical system and blocking a part of the light beam in the illumination optical system; and a stop plate movable to a second position not blocking the light beam;
A voice coil motor that moves the diaphragm plate between the first position and the second position;
A projection display device comprising: a detecting unit that detects a position of the diaphragm plate. A light valve that can be modulated for each pixel according to the input information,
A light source that emits light to irradiate the light valve;
An illumination optical system comprising a plurality of optical elements that irradiate the light valve with light emitted from the light source;
A projection lens for projecting reflected or transmitted light of the light valve;
A diaphragm plate that is located in the illumination optical system and is movable between a first position that blocks a part of the light beam in the illumination optical system and a second position that does not block the light beam,
Drive means for moving the diaphragm plate between the first position and the second position;
Urging means for urging the diaphragm plate to move from the first position to the second position;
A projection display device comprising: holding means for holding the urging means so as not to act on the diaphragm plate during normal operation. The holding means uses electromagnetic action, and
In an energized state, the biasing means is held so as not to act on the diaphragm plate,
3. The projection display device according to claim 2, wherein the diaphragm plate is not held in a state where energization is stopped. 4. The projection display device according to claim 2, wherein the driving unit moves the diaphragm plate to a position where the holding unit can be held. 5. The projection type image display apparatus according to claim 2, wherein the driving means is a voice coil motor.

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