JP2020030381A - Projection display device - Google Patents

Abstract

To provide a projection display device with which, in a configuration where an aperture is provided for each of an illumination optical system and a projection optical system, it is possible to project a high-contrast video while suppressing a reduction in the quality of a projected image due to a rise of temperature of a projection lens.SOLUTION: It is possible to narrow the aperture on the illumination optical system side at necessary timing by narrowing the aperture on the illumination optical system side in accordance with the temperature or luminous energy detected by detection means. Therefore, it is possible to provide a projection display device capable of projecting a high-contrast video while preventing a reduction in the quality of a projected image due to a rise of temperature of a projection lens.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a projection display device.

  In the projector device, a high-contrast image can be projected by reducing the light emitted from the light source. Patent Literature 1 discloses an example of a projector device in which an illumination optical system and a projection lens are each provided with a diaphragm unit.

JP 07-270719 A

  In a projector that projects an image in which a bright image and a dark image such as a moving image are appropriately switched, it is necessary to appropriately adjust the aperture in accordance with the projected image in order to increase the contrast and the dynamic range. Specifically, by analyzing the luminance of the video in real time, controlling the aperture according to the luminance change, correcting the luminance value and projecting, it is possible to project as a high contrast image even if it is a dark image it can.

  In a configuration in which two apertures are provided as in Patent Literature 1, when such aperture control is performed, it is possible to block leakage light by adjusting the aperture of the projection lens, so that high contrast is obtained. Can provide images. However, if the light of the projection lens is continuously blocked by the stop, the stop itself is heated by the blocked light and the temperature rises. Accordingly, when the temperature of the lens components of the projection lens also rises, the refractive index of the lens fluctuates, and there is a concern that the quality of the image displayed on the screen may be degraded such as displacement or defocus. In order to reduce such an influence, a method of cooling the projection lens with a fan or the like is conceivable, but it is not preferable because dust may enter the projection lens.

  Also, since the amount of light blocked by the projection lens decreases when the aperture of the illumination optical system is reduced, the aperture of the illumination optical system is always controlled to open and close according to the brightness of the image, thereby preventing the temperature of the projection lens aperture from rising. Conceivable. However, since the aperture of the illumination optical system takes a longer time from fully open to fully closed compared to the projection lens aperture, there is a concern that real-time adjustment cannot be performed in accordance with the switching of the brightness of the projected image, and the aperture of the illumination optical system is always reduced. Control is undesirable.

  In view of the above, the present invention aims to project a high-contrast image while preventing deterioration in the quality of a projected image due to a rise in the temperature of a projection lens in a configuration in which a stop is provided in each of an illumination optical system and a projection optical system. It is an object of the present invention to provide a projection display device capable of performing the following.

  In order to achieve the above object, light emitted from a light source, a light modulation element that modulates based on an input video signal, and a projection lens that projects light modulated by the light modulation element onto a projection surface First aperture means provided between the light source and the light modulation element for blocking a part of the light from the light source; and light provided on the projection lens and projected from the projection lens. Second aperture means for blocking a part of the light, a detection means for detecting the temperature of the second aperture means, and a control means for controlling the first aperture means and the second aperture means. And wherein the control means controls the first aperture means in accordance with the temperature detected by the detection means.

  Further, in order to achieve the above object, a light modulation element for modulating light emitted from a light source based on an input video signal, and a projection for projecting the light modulated by the light modulation element onto a projection surface A lens, a first aperture unit provided between the light source and the light modulation element for blocking a part of the light from the light source, and a first aperture unit provided on the projection lens and projected from the projection lens. Control means for blocking a part of the light beam, detecting means for detecting an amount of light blocked by the second stop means, and controlling the first and second stop means. And a control unit that controls the first diaphragm unit in accordance with the amount of light detected by the detection unit.

  In a configuration in which a stop is provided in each of the illumination optical system and the projection optical system, it is possible to project a high-contrast image while preventing the quality of the projected image from being degraded due to a rise in the temperature of the projection lens. It is possible to provide a projection type display device which can be used.

FIG. 1 is a schematic diagram of a projector device according to the present invention. FIG. 3 is a control block diagram of the projector device according to the present invention. FIG. 3A is a diagram illustrating a state in which the stop of the projection optical system is reduced. FIG. 3B is a diagram illustrating a state in which the stop on the illumination optical system side is narrowed. 5 is a flowchart for describing aperture control according to the first embodiment. FIG. 3 is a diagram illustrating a state in which a stop of an illumination optical system is stopped. FIG. 3 is a diagram illustrating a state in which a stop of a projection optical system is stopped. 9 is a flowchart for explaining aperture control according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
In the present embodiment, description will be made using a projector device (projection display device) using a reflection type liquid crystal display device as a light modulation device. However, the present invention can also be applied to a projector device using other light modulation elements, for example, a DMD (Digital Mirror Device) or a transmission type liquid crystal display element.

  First, the configuration of the illumination optical system will be described with reference to FIG.

  The light source used in the projector device (projection display device) is a light source that outputs white light, and for example, an ultra-high pressure mercury lamp, a xenon lamp, a laser, an LED, or the like can be used. The white light emitted from the light source bulb 1 of the light source is reflected by the reflecting mirror 2 and is incident on the fly-eye lens 3 and the fly-eye lens 4 as parallel light to be split. Thereafter, the PS conversion element 5 converts the randomly polarized light into P polarized light and emits the same.

  Next, the white light is condensed by the condenser lens 6 and then, by the dichroic mirror 7, the green (hereinafter referred to as G) component light and the red (hereinafter referred to as R) and blue (hereinafter referred to as B) component lights. Is separated into The G component light is converted into S-polarized light by the half-wave plate 8, enters the polarization beam splitter 9, is reflected by the polarization splitting surface, passes through the quarter-wave plate 10, and is converted into green component liquid crystal. It is supplied to the display element 11. The R component light and the B component light also enter the color selection element 12, the R component light is converted into P-polarized light, and the B component light enters the polarization beam splitter 13 as S-polarized light as it is. The S-polarized B component light is reflected by the polarization splitting surface of the polarization beam splitter 13, and the P-polarized R component light passes through the polarization splitting surface, passes through quarter-wave plates 14 and 16, respectively, and then becomes a red component. The light is supplied to the liquid crystal display element 15 and the blue component light 17.

  The polarization of the G, R, and B component lights is controlled by the respective liquid crystal display elements 11, 15, and 17 in accordance with the input video signal, and returns to the polarization beam splitters 9 and 13 again.

  Then, the polarization beam splitters 9 and 13 separate the component light supplied as projection light to the color combining prism 18 and the component returning to the light source direction according to the polarization state. The color combining prism 18 combines the G, R, and B component lights (projection light) and supplies the combined light to the projection optical system 200 (projection lens system). The supplied combined light passes through the incident-side lens components 19a and 19b of the projection lens, the aperture unit 21, and the output-side lens components 20a and 20b, and is then projected onto a projection surface such as a screen to project an image.

  As a stop of the illumination optical system, between the fly-eye lens 3 and the fly-eye lens 4, that is, between the light source and the liquid crystal display element, a stop blade 25 (first stop) for blocking the light beam split by the fly-eye lens 3. Aperture means). The aperture blade 25 is provided such that the plurality of blades are symmetrical with respect to the optical axis of the illumination optical system, and rotates the illumination optical system aperture motor 26 (geared motor) with the gear portion 27 as a fulcrum. It is configured so that a part of the light from the light source can be blocked. The aperture blades 25 may be controlled by one illumination optical system aperture motor 26 or may be controlled by using a plurality of them.

  FIG. 5 is a diagram illustrating a state in which the aperture blade 25 narrows the light beam, and is a diagram illustrating a state of the aperture control of the aperture blade 25 viewed from the condenser lens 6 side along the optical axis direction. FIG. 5A shows a state in which the aperture blade 25 is substantially open, and most of the light that has passed through the fly-eye lens 3 is incident on the projection optical system 200. FIG. 5B shows a state in which the diaphragm blade 25 is narrowed as compared with FIG. 5A, and only a part of the light that has passed through the pupil at the center of the optical axis of the fly-eye lens 3 is projected. Is not incident on FIG. 5C is a diagram in which the positional relationship between the diaphragm blade 25 and the fly-eye lens 3 in FIG. The fly-eye lens 3 is provided with a fly-eye that is divided into, for example, 5 × 5 pupils, and the F-number of the illumination optical system depends on how many eyes of the fly-eye lens 3 are blocked by the diaphragm blade 25. Can be adjusted.

  Next, the projection optical system 200 will be described with reference to FIG.

  The projection optical system 200 (projection lens) is configured by combining a plurality of lens components 19a, 19b, 20a, and 20b. As a stop of the projection optical system 200, between the lens component 19b and the lens component 20a, a projection lens stop 30 (second stop means) for blocking a part of light projected from the projection lens to the projection surface is provided. Is provided. The projection lens stop 30 is held by a stop holding plate 28 and arranged at the pupil position of the projection optical system 200. When driven by a projection optical system stop motor 29 (geared motor), light projected on a screen is emitted. Can be shielded from light. The projection lens stop 30 may be controlled by one projection optical system stop motor 29 or may be controlled by using a plurality of them. In the vicinity of the projection lens stop 30, a temperature detecting means 32 capable of measuring the temperature of the projection lens stop 30 and the lens components 19a, 19b, 20a, 20b is provided.

  FIG. 6 is a diagram showing a state in which the projection lens aperture 30 narrows a light beam, and is a diagram of a state of aperture control of the projection lens aperture 30 viewed from the screen side along the optical axis direction. FIG. 6A shows a state in which the projection lens diaphragm 30 is almost open and all the light beams 21a pass through the diaphragm unit 21, and FIG. 6B shows a state in which the projection lens diaphragm 30 is narrowed. In this state, a part of the luminous flux 21a is passing through the diaphragm 21 in a state where the luminous flux 21a is in the state. FIG. 6C is a diagram in which the positional relationship between the projection lens stop 30 and the light beam 21a in FIG. 6B is easily understood.

  FIG. 2 is a control block diagram of the projector device according to the present invention. A control unit 120 is provided in the projector device 100, and includes a projector control unit 31 and a luminance analysis unit 40. When a video signal is transmitted from an external input device such as a PC, the projector control means 31 generates image data for projection display and the liquid crystal display elements 11 and 15 so that the generated image data is displayed. , 17 are displayed. The brightness analysis means 40 of the control unit 120 performs a brightness analysis of the input video signal. Specifically, the luminance analysis unit 40 detects the luminance histogram of the video signal in real time for each frame, and specifies information indicating the luminance of the video signal for determining whether the image is a bright image or a dark image. The projector control unit 31 controls the projection optical system aperture motor 29 and the illumination optical system aperture motor 26 according to the temperature detected by the temperature detection unit 32 and the result of the luminance analysis by the luminance analysis unit 40. That is, aperture control of the aperture blade 25 and the projection lens aperture 30 is performed. Details of the aperture control will be described later.

  Next, the effects of the illumination system stop and the projection optical system stop in the present invention will be described. FIG. 3A shows a state in which the aperture blade 25 (first aperture means) is substantially open and the projection lens aperture 30 (second aperture means) is apertured. FIG. 3B shows a state in which the aperture blade 25 (first aperture means) is apertured and the projection lens aperture 30 (second aperture means) is also apertured.

  As shown in FIG. 3A, when the contrast is increased by narrowing only the projection lens aperture 30, light passing through the color separation / combination system is blocked only by the projection lens aperture 30. Continue, the temperature of the projection lens aperture rises.

  In addition, the fly-eye lens 4 of the illumination optical system is set to the same eye as the fly-eye lens 3 and the eyes are provided so as to correspond to each other on the optical axis. The light thus emitted enters the fly-eye lens 4 and is sent to the color separation / combination system. However, unnecessary light that is not emitted in parallel from the light source may also enter the fly-eye lens 3, and such light passes through different eyes of the fly-eye lens 4 and is provided on the projection lens side as leakage light. Is irradiated to the lens component. Further, some of the light incident on the polarization beam splitters 9 and 13 is transmitted through the polarizing film without being reflected, and such light is also irradiated to the lens component as leak light. Such leakage light can be blocked by narrowing the projection lens aperture 30, so that the contrast can be increased. However, such leakage light also causes a rise in the temperature of the projection lens aperture. Then, when the temperature of the projection lens aperture rises, the temperature of the lens components 19a, 19b, 20a, 20b of the projection lens arranged in the vicinity also rises, the refractive index of the lens components changes, and the resolution of the projection image changes. May be degraded or out of focus. A comparison between a case in which only the aperture blade 25 of the illumination system diaphragm is stopped and a case in which only the projection lens diaphragm 30 is stopped down indicates that the projection lens diaphragm 30 has diffracted light generated in the liquid crystal display element in addition to the above-described leaked light. Can also be shaded, so the latter can be said to have a higher contrast value.

  On the other hand, as shown in FIG. 3B, when the diaphragm blades 25 are also squeezed in addition to the projection lens diaphragm 30, the amount of light transmitted to the color separation / synthesis system decreases, so that the amount of light blocked by the projection lens diaphragm decreases, and The temperature rise of the lens stop can be reduced. Further, by squeezing the aperture blade 25, which is an illumination system aperture, it is possible to block light leaked from the fly-eye lens and light leaked from the polarization beam splitter. Therefore, by reducing the aperture of the illumination optical system diaphragm 25, it is possible to increase the contrast of the projected image and to prevent a change in the refractive index of the lens component due to a rise in the temperature of the projection lens, deterioration of the resolution of the projected image, and occurrence of defocus. it can.

  By the way, in a projector that projects an image in which a bright image and a dark image such as a moving image are appropriately switched, it is necessary to appropriately adjust the aperture in accordance with the projected image in order to widen the contrast and the dynamic range. The projection lens stop 30 can be driven at high speed in accordance with a frame of an image. However, as can be seen from FIG. 3, the aperture blade 25 of the illumination optical system has a wider opening / closing width than the projection lens diaphragm 30, so that it is difficult to open / close the frame in units of video. That is, it can be said that the time required for the projection lens aperture 30 to transition from the fully open state to the fully closed state is shorter than the time required for the aperture blade 25 of the illumination optical system to transition from the fully open state to the fully closed state. Further, even if the diaphragm blade 25 is driven at a high speed, the inertia force is increased due to the large gravity of the diaphragm blade 25 itself, and there is a high possibility that the stopping accuracy is deteriorated.

  Therefore, even when the bright image and the dark image are switched, the aperture blade 25 of the illumination optical system cannot be opened and closed in real time, and a time lag of several frames may occur. If such a time lag frequently occurs when switching to an image, the viewer will feel uncomfortable. That is, it can be said that it is preferable to control the aperture blade 25 of the illumination optical system so as not to open and close as much as possible.

  Based on the above, in the present invention, the contrast control according to the video is performed without time lag, and the following aperture control is performed to prevent the temperature of the projection lens from rising, so that the viewer does not feel uncomfortable as much as possible. You can do so.

  FIG. 4 is a flowchart for explaining the aperture control process. The processing shown in the flowchart of FIG. 4 is realized by the control unit 120 of the projector device 100 functioning as a control unit. The following control may be performed in the cycle of the frame frequency, or may be performed in units of time required for opening and closing the projection lens.

  In step S401, the luminance analysis unit 40 of the control unit 120 analyzes the luminance histogram of the input video signal and acquires information (luminance information) indicating the luminance of the video signal. In S402, the projector control means 31 of the control unit 120 determines whether or not the video signal is a dark image based on the information indicating the luminance. For example, when the number of data in the luminance range of 0 to 20 in the luminance histogram is 80% or more, the image is determined to be a dark image, and when the number of data is less than 80%, the image is determined to be a bright image. If it is determined in S402 that the image is a bright image, the aperture control is unnecessary, and the process advances to S404. If the aperture is stopped down, the aperture blade 25 of the illumination-side aperture and the projection of the projection lens-side aperture are performed. The lens aperture 30 is opened appropriately. Then, the process proceeds to S407, where it is determined whether the input video signal is completed. If the video signal is still input, the process returns to S401.

  On the other hand, if it is determined in step S402 that the image to be projected is a dark image, the process advances to step S403 to stop down the projection lens aperture 30 on the projection lens side so as to perform contrast control in accordance with the image. Note that the projector control means 31 electrically changes the luminance gamma value of the video signal while the projection lens aperture 30 is being stopped, and outputs a value obtained by multiplying the luminance value by a gain to the liquid crystal display element 11. To In other words, the liquid crystal display element 11 outputs a corrected signal that enhances the image so that the image is projected onto the projection surface with a luminance value higher than the luminance value of the input image signal. As a result, the dynamic range can be expanded, and the black portion of the dark image becomes darker, and the other portions of the image are gained, so that the substantial contrast can be improved. That is, by performing image adjustment in conjunction with the projection lens aperture 30, image quality can be improved to improve contrast and dynamic range.

  In S405, the projector control unit of the control unit 120 determines whether the temperature acquired by the temperature detection unit 32 provided near the projection lens is equal to or higher than a preset threshold. As the threshold temperature set here, it is preferable to set an allowable upper limit temperature at which the refractive index of the projection lens component does not change. If it is determined in step S405 that the temperature is equal to or higher than the threshold value, the projection lens-side diaphragm may be heated in this state, and the refractive index of the projection lens component may change. The diaphragm blade 25 as the side diaphragm is squeezed. As a result, the light beam transmitted to the color separation / combination system is reduced, so that the amount of light blocked by the projection lens aperture is reduced, and the temperature of the projection lens aperture can be prevented from rising. If it is determined in step S405 that the temperature is not equal to or higher than the threshold, the process advances to step S407 to determine whether a video signal is input. If the video signal is still input, the process returns to step S401.

  As described above, by stopping down the stop on the illumination optical system side in accordance with the temperature detected by the temperature detecting means, the stop on the illumination optical system side can be stopped at a necessary timing. That is, it is possible to provide a projector device capable of projecting a high-contrast image while preventing the quality of a projected image from being degraded due to a temperature rise of the projection lens.

  In the present embodiment, the description has been made using an example in which the aperture is controlled in two stages in which the aperture is controlled according to the numerical value of the luminance histogram and the threshold value of the temperature. However, the aperture control may be performed in a stepwise manner. Good. At this time, the aperture control can be performed stepwise by adjusting the aperture amounts (the sizes of the apertures) of both apertures.

  Further, in the present embodiment, the aperture control of the illumination-side aperture is performed in accordance with the detection result of the temperature detecting means provided near the projection lens, but a light quantity detecting means may be used instead of the temperature detecting means. In such a case, when it is determined that the irradiation of the light amount equal to or more than the predetermined time has continued for the predetermined time and the temperature of the projection lens aperture is rising, the illumination side aperture may be controlled to be reduced.

  In this embodiment, as shown in FIG. 5, the fly-eye lens 3 and the fly-eye lens 4 divide light evenly, and adjust the light flux emitted from the light source to have a circular shape to perform color separation / combination. The description has been made using the example of the illumination optical system to be sent to the system. However, the same control can be performed in the case of an illumination optical system adjusted so that the light beam emitted from the light source has an elliptical shape. In the case of such an illumination optical system, the amount of movement of the illumination optical system can be reduced by setting the opening / closing direction of the aperture on the short side of the elliptical shape on the illumination side aperture. The time required for opening and closing can be shortened. Thus, it is possible to control the aperture of the illumination optical system without switching the video and without a time lag, and it is possible to reduce a sense of discomfort felt by the viewer.

  Note that, in the present embodiment, an example in which the control unit 120 of the projector device 100 performs control has been described. However, a control unit is also provided in the projection lens, and the control unit of the projection lens responds to an instruction from the control unit 120. Fine aperture control may be performed.

(Second embodiment)
In the present embodiment, description will be made mainly on the points different from the first embodiment, and the description of the same parts will be omitted.

  In the first embodiment, when the illumination-side stop is stopped down in S406, while the projection lens-side stop is stopped down, the illumination-side stop is stopped down even if the temperature near the projection lens no longer exceeds the threshold value. The example in which the state is set has been described. However, when the temperature is not higher than the threshold value, the illumination-side aperture may be opened.

  FIG. 7 is a flowchart for explaining the aperture control processing according to the present embodiment. The processing illustrated in the flowchart of FIG. 7 is realized by the control unit 120 of the projector device 100 functioning as a control unit. The following control may be performed in a frame cycle, or may be performed in units of time required for opening and closing the projection lens.

  Steps S701 to S707 in FIG. 7 are the same as steps S401 to S407 in FIG.

  In step S708, when it is determined in step S705 that the temperature is not equal to or higher than the threshold, when the diaphragm blade 25 of the illumination optical system aperture is narrowed, control is performed to open the diaphragm blade 25 of the illumination optical system aperture. Thereafter, the process proceeds to S707, where it is determined whether the input video signal has been completed. If the video signal is still input, the process returns to S701.

  Also in the present embodiment, the aperture on the illumination optical system side can be narrowed at a necessary timing by narrowing the aperture blade 25 of the illumination optical system aperture according to the temperature detected by the temperature detection unit. That is, it is possible to provide a projector device capable of projecting a high-contrast image while preventing the quality of a projected image from being degraded due to a temperature rise of the projection lens.

1 light source lamp 11 liquid crystal display element (G)
15 Liquid crystal display device (R)
17 Liquid crystal display device (B)
25 aperture blade 30 projection lens aperture 32 detecting means 120 control unit (control means)
200 Projection optical system (projection lens)

Claims (7)

A light modulation element that modulates light emitted from the light source based on an input video signal,
A projection lens that projects light modulated by the light modulation element onto a projection surface,
A first aperture unit provided between the light source and the light modulation element, for blocking a part of light from the light source;
A second aperture unit provided on the projection lens for blocking a part of light projected from the projection lens;
Detecting means for detecting the temperature of the second throttle means;
Control means for controlling the first stop means and the second stop means, a projection display device,
The projection type display device, wherein the control unit controls the first aperture unit according to the temperature detected by the detection unit.   2. The projection display device according to claim 1, wherein when the temperature detected by the detection unit is equal to or higher than a threshold, the control unit stops the first stop unit. 3. A light modulation element that modulates light emitted from the light source based on an input video signal,
A projection lens that projects light modulated by the light modulation element onto a projection surface,
A first aperture unit provided between the light source and the light modulation element, for blocking a part of light from the light source;
A second aperture unit provided on the projection lens for blocking a part of light projected from the projection lens;
Detecting means for detecting the amount of light blocked by the second aperture means;
Control means for controlling the first stop means and the second stop means, a projection display device,
The projection type display device, wherein the control means controls the first stop means in accordance with the amount of light detected by the detection means.   4. The projection display device according to claim 1, wherein the control unit controls the second aperture unit according to information indicating luminance of an image based on the video signal. 5. .   The control means narrows down the second aperture means when it is determined from the information indicating the luminance of the image based on the video signal that the input video signal is a dark image. Item 5. A projection display device according to item 4.   5. The control device according to claim 4, wherein when the second diaphragm device is stopped down, the control is performed such that the image signal is projected on a projection surface with a luminance value higher than the luminance value of the input video signal. 6. 6. The projection display device according to 5.   The time required for the second throttle means to transition from the fully open state to the fully closed state is shorter than the time required for the first throttle means to transition from the fully open state to the fully closed state. The projection type display device according to claim 1.