JP4415577B2 - Projection display - Google Patents

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
However, in the example of the fixed asymmetric aperture of the conventional method described above, it is difficult not only to cope with a sudden change in the image, but also in the state where the diaphragm plate is inserted in the optical path, When a failure occurs in the drive circuit, the diaphragm plate cannot be quickly retracted from the optical path, and a high luminance state cannot be maintained even if it is continuously used.
[0006]
The present invention solves the above problems, and in a drive mechanism of a diaphragm plate that can be driven at high speed, including a diaphragm plate that blocks the luminous flux of illumination light, a failure of the drive device with the diaphragm plate inserted in the optical path, It is an object of the present invention to provide a projection display device that can retract the aperture plate from the optical path even when a drive circuit failure occurs.
[0007]
To achieve the above object, a projection display device includes a light valve that can be modulated for each pixel in accordance with an input signal, a light source that emits light to irradiate the light valve, and a light valve that collects light emitted from the light source. An illumination optical system comprising a plurality of optical elements that irradiate the light, a projection lens that projects light reflected or transmitted by the light valve, and a first lens that is located in the illumination optical system and blocks a part of the light beam in the illumination optical system. A diaphragm plate that can be moved to a second position that does not block the light beam, a voice coil motor that moves the diaphragm plate between the first position and the second position, and a diaphragm plate that is in the second position. Biasing means for urging and fixing, holding means for holding the urging means at a position where the urging force of the urging means does not act on the diaphragm plate, and between the first position and the second position of the diaphragm plate Detecting means for detecting.
[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 enlarges and projects the light reflected in the 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 VCM. When 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), the actuator hub 17 is rotated around a 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 direction of the arrow B by the engaging portion 25 of the actuator hub 17 by the VCM , 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]
As described above, according to the present invention , not only the amount of blocking a part of the light beam at a predetermined position in the illumination optical path of the projection display apparatus is changed at high speed, but also a drive circuit failure occurs during use. Since the diaphragm plate can be quickly retracted to a position where it does not block the optical path, a high-luminance image can be continuously projected even if it is continuously used.
[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 (3)

A light valve that can be modulated for each pixel according to the input signal,
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;
Biasing means for biasing and fixing the diaphragm plate to a second position;
Holding means for holding the urging means at a position where the urging force of the urging means does not act on the diaphragm plate;
Detecting means for detecting a distance between the first position and the second position of the diaphragm plate;
A projection-type display device comprising: The holding means uses electromagnetic action, and
In the energized state, hold the urging means so that the urging means does not act on the diaphragm plate,
The projection display apparatus according to claim 1 , wherein the energizing unit energizes the diaphragm plate without holding the energizing unit in a state where energization is stopped. 3. The projection type according to claim 1 , wherein when the diaphragm plate moves to the first position, the voice coil motor moves the biasing unit to a position where the holding unit can be held. Display device.

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