JP2005181591A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the quantity of light of a light source based upon variation in quantity of wavelength light used actually for image formation without disturbing a travel of all of luminous flux to irradiate a light valve at all. <P>SOLUTION: A projector has a light source 11, a reflecting mirror 23 which reflects light emitted by the light source 11 to a specified direction, and a color separating and composing prism 24 which separates the light having been reflected by the reflecting mirror 23 by the three primary colors R, G, and B, and adjusts electric power supplied from a light source driving part 13 to the light source 11 based upon the quantity of leak light detected by a light receiving sensor 60 detecting leak light transmitted through the reflecting mirror 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector that modulates light emitted from a light source by a light valve to form image light and enlarges and projects the formed image light.

  Projectors can be broadly classified into two types according to the type of light valve for forming image light. One is a transmissive projector using a transmissive liquid crystal panel or the like as a light valve. The other is a reflective projector that uses a DLP (registered trademark of Texas Instruments (TI)) or a reflective liquid crystal panel as a light valve. However, both types of projectors are formed by guiding the light emitted from the light source to the light valve by the illumination optical system, and modulating the light irradiated to the light valve by the light valve to form image light. This is common in that image light is enlarged and projected by the projection optical system. Therefore, a decrease in the amount of light from the light source directly affects a decrease in the brightness of the projected image. For this reason, a projector has been developed that includes means for detecting a decrease in the amount of light of the light source due to aging or the like and controlling the light source based on the detection result to keep the light amount as constant as possible.

  For example, Patent Document 1 includes a light source light amount detection unit, and feeds back a light amount detected from the light source light amount detection unit to a light source control device, thereby making the light amount of the projection light source constant. A display device is disclosed. FIG. 2 shows a schematic configuration of the projection display device disclosed in Patent Document 1. As shown in FIG. In this projection display device, a light amount detector 102 is provided on the optical path between the projection light source 100 and the light valve 101, and the projection light source control device 103 operates according to the light amount detected by the light amount detector 102. The light quantity of 100 is controlled.

Further, Patent Document 2 is characterized in that a light receiving sensor is provided behind a dichroic mirror that color-separates light emitted from a light source and irradiates a liquid crystal panel, and the light source is controlled based on the detection result of the light receiving sensor. A liquid crystal projector device is disclosed. FIG. 3 shows a schematic configuration of the liquid crystal projector apparatus disclosed in Patent Document 2. The liquid crystal projector includes an LCD panel 200, a discharge lamp 201, a lamp driving unit 202, a dichroic mirror 203, a light receiving sensor 204, and a microcomputer 205 as a control unit. Further, the dichroic mirror 203 reflects a red wavelength light and transmits a light of other wavelengths, and a dichroic mirror 203a reflects a green wavelength light and transmits a light of other wavelengths. 203b and a dichroic mirror 203c that reflects light of blue wavelength and transmits light of other wavelengths. Therefore, when the light emitted from the discharge lamp 201 and collimated by the condenser lens 206 is irradiated to the dichroic mirror 203, the irradiated light is changed to the three primary colors of RGB according to the reflection spectral characteristics of the dichroic mirrors 203a to 203c. The LCD panel 200 is irradiated with each color light after being decomposed. The light receiving sensor 204 is disposed at a position facing the discharge lamp 201 with the dichroic mirror 203 interposed therebetween, and among the light incident on the dichroic mirror 203, the light transmitted through the mirror 203 (light in a wavelength range other than the three primary colors). ) Is received, and a voltage corresponding to the amount of light is output to the microcomputer 205. The microcomputer 205 outputs a control signal to the lamp driving unit 202 based on the input voltage, and the lamp driving unit 202 supplies lamp power to the discharge lamp 201 according to the input control signal. In the liquid crystal projector device disclosed in Patent Document 2, when the amount of light received by the light receiving sensor 204 is reduced, the lamp power is increased and the light amount of the discharge lamp 201 is kept constant by the above configuration. Yes.
JP-A-4-53942 JP 2000-28988 A

  In the configuration disclosed in Patent Document 1, a light amount detector is provided on the optical path of light irradiated on the light valve. Therefore, the light quantity detector shadows on the light irradiating the light valve, and the light quantity detector shadows also on the image finally projected on the screen. In order to reduce the influence of the shadow as much as possible, a light amount detector must be installed at the end of the optical path. In fact, even in the configuration disclosed in Patent Document 1, a light amount detector is installed at a position slightly overlapping the optical path. However, only weak light reaches the light amount detector installed at the end of the optical path, and accurate light amount detection is difficult. Moreover, there is a possibility that the light quantity cannot be detected if the optical path is slightly shifted due to replacement of the light source.

  In this regard, in the configuration disclosed in Patent Document 2, since the light receiving sensor corresponding to the light amount detector is provided behind the dichroic mirror, there is no inconvenience as seen in the configuration of Patent Document 1. However, since the dichroic mirror has the reflection spectral characteristics (wavelength selectivity) as described above, the light that can be received by the light receiving sensor provided behind the dichroic mirror is light having a wavelength outside the wavelength range of the three primary colors. It is limited to. On the other hand, the image light is formed by light of the three primary colors reflected by the dichroic mirror. Therefore, the configuration of Patent Document 2 cannot control the light source based on the change in the amount of wavelength light actually used for image formation, despite the purpose of preventing a decrease in luminance of the projected image. There is a problem.

  An object of the present invention is to make it possible to control the light amount of a light source based on a change in the light amount of wavelength light actually used for image formation without obstructing the progress of the total luminous flux irradiated to the light valve. It is in.

  The projector of the present invention that achieves the above object includes a light source, a reflection mirror that reflects light emitted from the light source in a predetermined direction, and a light receiving device that is provided behind the reflection mirror and detects leakage light transmitted through the reflection mirror. A sensor, a color separation unit that separates the light reflected by the reflection mirror into at least three primary colors of RGB, a light valve that modulates each color light emitted from the color separation unit to form image light, and a light Color synthesis means for synthesizing the image light of each color formed by the bulb, a projection optical system for projecting the image light synthesized by the color synthesis means, and control for controlling the light quantity of the light source based on the detection result of the light receiving sensor Part. Here, the light of all wavelengths emitted from the light source is incident on the reflection mirror, and the light of all the wavelengths (at least the three primary color wavelengths of RGB) is several percent on the back side of the reflection mirror. Leaking. Therefore, the light receiving sensor provided behind the reflection mirror detects all wavelengths of light emitted from the light source (at least the three primary colors of RGB light), and the light source is controlled based on the detection result. As a matter of course, most of the light incident on the reflection mirror is reflected by the reflection mirror and later becomes image light. That is, in the projector of the present invention, the light source is controlled based on the change in the amount of light having the same wavelength as the light that is the image light, so that a reduction in the brightness of the projected image is avoided more accurately.

  In the projector of the present invention, since the light receiving sensor is provided outside the optical path of the light emitted from the light source, part of the light is not blocked by the light receiving sensor. In addition, since the light source is controlled based on a change in the amount of wavelength light used for image formation later, it is possible to prevent the brightness of the projected image from being lowered more accurately.

  Hereinafter, an example of an embodiment of a projector according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of the projector according to the present embodiment. The projector of this example includes a light source device 10, an illumination optical system 20, a reflective light valve 30, a projection optical system 40, and a control unit (not shown).

  The light source device 10 includes a light source 11 including a discharge lamp such as a metal halide lamp, a xenon lamp, and a high-pressure mercury lamp, a reflector 12 for causing light emitted from the light source 11 to enter the illumination optical system 20 with high efficiency, and not illustrated. And a light source driving unit 13 for supplying power to the light source 11 in accordance with a control signal output from the control unit.

  The illumination optical system 20 includes a rod lens 21, a relay lens 22, a reflection mirror 23, and a color separation / synthesis prism 24. The rod lens 21 is a prismatic rod glass, and each surface is mirror-finished. The light emitted from the light source device 10 enters the rod lens 21 from one end surface in the longitudinal direction of the rod lens 21, and the luminance distribution is made uniform while traveling while totally reflecting inside the rod lens 21, so that the longitudinal direction The light exits from the other end face. The relay lens 22 is a plano-convex lens, and is disposed with the convex surface facing the exit end face of the rod lens 21 and the plane facing the reflecting mirror 23. Accordingly, the light emitted from the emission end face of the rod lens 21 is converged by the relay lens 22 and focused on the reflection surface of the reflection mirror 23.

  The reflection mirror 23 does not have wavelength selectivity like a dichroic mirror and is a mirror designed to reflect all incident light, and reflects the incident light toward the color separation / combination prism 24. However, due to its nature, several percent of the light incident on the reflecting mirror 23 passes through the reflecting mirror 23 and leaks to the back side.

  The color separation / combination prism 24 separates the incident light by the reflection action of the reflection mirror 23 into three color lights of RGB, and emits the respective color lights from different entrance / exit surfaces predetermined for each color light. As will be described in detail later, it is formed by forming a color image light by combining light (monochromatic image light) incident on the incident / exit surface at a predetermined incident angle, which is formed by the reflective light valve 30. The emitted image light is emitted toward the projection optical system 40. In this sense, the color separation / combination prism 24 is included in the projection optical system, but whether the color separation / combination prism 24 is classified as the illumination optical system 20 or the projection optical system 40 is irrelevant to the essence of the present invention. It is.

  The reflective light valve 30 in this example is a DLP. In this example, three DLPs 30 are respectively arranged corresponding to the three entrance / exit surfaces of the color separation / combination prism 24 from which each color light of RGB is emitted (for convenience of explanation, only one DLP 30 is shown in FIG. 1). Is illustrated). Each DLP 30 has tens of thousands to hundreds of thousands of micromirrors that are controlled independently, and each micromirror is inclined ± 10 ° or ± 12 ° based on the image data. Then, the color light reflected by the micromirror tilted by + 10 ° or + 12 ° is incident on the incident / exit surface of the color separation / combination prism 24 at a predetermined angle, and the color light of other colors incident from the other DPL 30 at the same angle. Are combined into color image light. On the other hand, the color light reflected by the micromirror tilted by −10 ° or −12 ° is incident on the incident / exit surface of the color separation / combination prism 24 at a predetermined angle different from the above, and the color light incident from the other DLP 30. It is emitted without being synthesized. Although further description of the configuration and function of each DLP 30 is omitted, the DLP 30 of this example is a known DLP, and the configuration and function are the same as the configuration and function of the known DLP.

  The projection optical system 40 is composed of two or more lenses or mirrors, or a combination of lenses and mirrors. The projection optical system 40 magnifies and projects the color image light emitted from the color separation / combination prism 24 onto the screen 50. The color light reflected by the micromirror tilted by −10 ° or −12 ° and incident on the color separation / combination prism 24 is emitted from the color separation / combination prism 24 at an angle that does not enter the projection optical system 40. The However, whether to use the color light reflected by the micromirror tilted in the plus direction as the image light or the color light reflected by the micromirror tilted in the minus direction is a design matter. If the color light reflected by the micromirror tilted in the minus direction is used as image light, the optical path of the color light reflected by the micromirror tilted in the plus direction and the light beam tilted in the minus direction are used. The relationship between the color light reflected by the micromirror and the optical path is reversed.

  Next, the characteristic structure of the projector of this example will be described. In the projector of this example, the light receiving sensor 60 is provided behind the reflecting mirror 23 and on the optical axis of the light incident on the reflecting mirror 23. The light receiving sensor 60 is a photodiode, receives light (leakage light) that has passed through the reflection mirror 23 and leaked to the back side, and outputs a voltage corresponding to the amount of the leaked light. The voltage output from the light receiving sensor 60 is input as a detection signal to a control unit (not shown). The control unit compares the voltage of the detection signal with a reference voltage input from a reference voltage generation unit (not shown), and outputs a control signal to the light source driving unit 13 based on the difference. Specifically, when the voltage of the detection signal is higher than the reference voltage, the power supplied to the light source 11 is decreased, and when the voltage of the detection signal is lower than the reference voltage, the power supplied to the light source 11 is increased. Outputs a control signal that instructs The light source driving unit 13 increases or decreases the power supplied to the light source 11 according to the control signal output from the control unit as described above, and keeps the light amount of the light source 11 constant. Note that the initial value of the power supplied to the light source 11 is set below the rating, and the supplied power is increased or decreased in a range between the initial value and the rated value.

  Until now, a color that functions as both a color separation means that separates light emitted from a light source into RGB color lights and a color composition means that combines single-color image light reflected by a light valve into a color image. A configuration having a decomposition / combination prism has been described. However, the color separation means can be realized by a dichroic mirror or a dichroic prism, and the color composition means can be realized by a prism different from the prism that realizes the color separation means. In this case, it is obvious from the above description that the light receiving sensor is provided behind the reflection mirror provided on the optical path closer to the light source than the dichroic mirror or dichroic prism that realizes the color separation means. The light valve constituting the projector of the present invention is not limited to the DLP, and may be a transmissive liquid crystal panel, a reflective liquid crystal panel, or the like. Further, FIG. 1 illustrates a configuration in which the reflection mirror 23 is one, but the number of reflection mirrors is not limited, and the number of light receiving sensors is not limited. In FIG. 1, a space is provided between the reflecting mirror 23 and the light receiving sensor 60, but the light receiving sensor 60 may be directly attached to the back surface of the reflecting mirror 23. In short, light that has been emitted from the light source and leaked to the back side of the reflection mirror on which light before color separation is incident is detected by the light receiving sensor, and the light source is based on the detection result. It is the gist of the present invention to control.

1 is a schematic configuration diagram illustrating an example of a projector according to the present invention. It is the structure schematic which shows an example of the conventional projector. It is the structure schematic which shows the other example of the conventional projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source device 11 Light source 12 Reflector 13 Light source drive part 20 Illumination optical system 21 Rod lens 22 Relay lens 23 Reflection mirror 24 Color separation / synthesis prism 30 Reflection type light valve (DLP)
40 Projection optical system 50 Screen 60 Light receiving sensor

Claims (2)

A light source;
A reflection mirror that reflects light emitted from the light source in a predetermined direction;
A light receiving sensor that is provided behind the reflecting mirror and detects leakage light transmitted through the reflecting mirror;
Color separation means for separating light reflected by the reflection mirror into at least three primary colors of RGB;
A light valve that modulates each color light emitted from the color separation means to form image light;
Color synthesis means for synthesizing image light of each color formed by the light valve;
A projection optical system for projecting the image light color-synthesized by the color synthesis means;
A projector having a control unit that controls a light amount of the light source based on a detection result of the light receiving sensor;   The projector according to claim 1, wherein the control unit compares the voltage output from the light receiving sensor with a reference voltage, and adjusts the power supplied to the light source so that the two voltages match.

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