JP2013242503A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type display device that can improve in contrast and chromatic purity.SOLUTION: A projection type display device includes a dichroic mirror 102 for separating light from a light source 101 into plural color light beams, an X prism 114 for combining three color light beams modulated according to an image signal, and plural light volume control units that are provided on respective optical paths of the plural color light beams separated by the dichroic mirror, between the dichroic mirror and the X prism 114, and control the light volume of the plural color light beams.

Description

  The present invention relates to a projection display device such as a liquid crystal projector.

  The conventional liquid crystal projector has a problem in that the contrast and color purity of the projected image are deteriorated due to leakage light because it is difficult to completely block light due to the characteristics of the image modulation element. Therefore, Patent Documents 1 and 2 propose a method of improving the contrast by controlling the diaphragm and the like from the average brightness of the video.

JP 2007-11393 A JP 2008-139857 A

  However, although Patent Documents 1 and 2 can improve the contrast by controlling the amount of white light or synthesized light from the light source, it is difficult to improve the color purity.

  An object of the present invention is to provide a projection display device capable of improving contrast and color purity.

  The projection display device of the present invention includes a color separation unit that separates light from a light source into a plurality of color lights, a combination unit that combines three color lights modulated in accordance with a video signal, the color separation unit, and the combination And a plurality of light quantity adjusting means for adjusting the light quantity of the plurality of color lights provided in each optical path of the plurality of color lights separated by the color separation means.

  ADVANTAGE OF THE INVENTION According to this invention, the projection type display apparatus which can improve contrast and color purity can be provided.

It is an optical path diagram of the liquid crystal projector of the present invention. Example 1 It is a block diagram of the light quantity control system of the liquid crystal projector shown in FIG. Example 1 It is a graph used for the light quantity control system shown in FIG. Example 1 It is an optical path diagram of the liquid crystal projector of the present invention. (Example 2) FIG. 5 is a block diagram of a light amount control system of the liquid crystal projector shown in FIG. 4. (Example 2) It is a histogram used for the light quantity control system shown in FIG. (Example 2)

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

  FIG. 1 is an optical path diagram of the liquid crystal projector (projection display device, image display device) of the first embodiment. The liquid crystal projector includes a light source 101, dichroic mirrors 102 and 103, a mirror 104, light amount adjustment units 105 to 107, polarization beam splitters (PBS) 108 to 110, liquid crystal panel elements 111 to 113, an X prism 114, and a projection lens 115.

  The light source 101 is a light source that outputs white light, and includes, for example, an ultrahigh pressure mercury lamp, a xenon lamp, or the like. However, the light source 101 is not limited to a lamp such as a laser or an LED.

  The dichroic mirror 102 is a first color separation unit that transmits color light in the blue wavelength band (B) and red wavelength band (R) and reflects and separates color light in the green wavelength band (G). As a result, the white light from the light source 101 is separated into G color light and RB color light (combined light) by the dichroic mirror 102. G color light (first wavelength region light, first color component light or first color light), R color light (second wavelength region light, second color component light or second color light), The color light of B (light in the third wavelength region, light of the third color component, or third color light) has a different wavelength region. The optical path of the G color light is bent by the mirror 104.

  The dichroic mirror 103 is a second color separation unit that reflects R color light and transmits B color light. As a result, R color light and B color light are separated.

  The G color light passes through the light amount adjustment unit 105 via the mirror 104, the R color light reflected from the dichroic mirror 103 passes through the light amount adjustment unit 106, and the B color light transmitted through the dichroic mirror 103 passes through the light amount adjustment unit 107. .

  The plurality of light amount adjusting units 105, 106, and 107 are light amount adjusting means that arbitrarily adjust the light amount of each color light between 0% and 100%. The light amount adjusting units 105, 106, and 107 are configured by, for example, an optical aperture or a transmissive liquid crystal panel element. The optical aperture has aperture blades that are moved to change the aperture diameter. The transmittance of the transmissive liquid crystal panel element changes due to energization of the liquid crystal.

  The light amount adjustment units 105, 106, and 107 are disposed on the optical path between the dichroic mirror 102 and the X prism 114. More specifically, the light amount adjusting unit 105 is arranged at an appropriate position of an optical path between the dichroic mirror 102 and the mirror 104, between the mirror 104 and the PBS 108, between the PBS 108 and the liquid crystal panel element 111, and between the PBS 108 and the X prism 114. Should just be arranged. The light amount adjusting units 106 and 107 are disposed on the optical path between the dichroic mirror 103 and the X prism 114. The light amount adjusting unit 106 may be disposed at an appropriate position on the optical path between the dichroic mirror 103 and the PBS 109, between the PBS 109 and the liquid crystal panel element 112, and between the PBS 109 and the X prism 114. The light amount adjusting unit 107 may be disposed at an appropriate position on the optical path between the dichroic mirror 103 and the PBS 110, between the PBS 110 and the liquid crystal panel element 113, and between the PBS 110 and the X prism 114.

  The G color light that has passed through the light amount adjustment unit 105 enters the PBS 108, the R color light that has passed through the light amount adjustment unit 106 enters the PBS 109, and the B color light that has passed through the light amount adjustment unit 107 enters the PBS 110.

  The PBSs 108 to 110 have polarization separation surfaces that reflect S-polarized light and transmit P-polarized light, and each color light is incident on the PBSs 108 to 110 as S-polarized light and reflected by an appropriate wave plate (not shown). The G, R, and B color lights reflected by the PBSs 108 to 110 enter the liquid crystal panel elements 111, 112, and 113, respectively.

  The liquid crystal panel elements 111, 112, and 113 are reflective liquid crystal display elements that modulate and reflect light of each color component (color light) according to a video signal, and function as image modulation elements. The liquid crystal panel elements 111, 112, and 113 reflect each color light as P-polarized light, return to the polarization beam splitter again, and are separated into the color light supplied to the X prism 114 and the light component returning to the light source direction according to the polarization state. .

  The X prism 114 is a combining unit that combines the G, R, and B color lights, and supplies the combined light to the projection lens 115. The projection lens 115 projects the supplied combined light onto a screen or the like and displays an image.

  FIG. 2 is a block diagram of the light quantity control system of this embodiment. The light quantity control system includes a video signal input unit 201, a matrix calculation unit 202, APL detection units 203, 204, and 205, an APL detection period setting unit 206, and adjustment amount calculation units 207, 208, and 209.

  A video signal is input to the video signal input unit 201. The matrix calculation unit 202 performs matrix calculation and converts the video signal into G, R, and B signals from the color format of the input video signal. For example, when the video signal is a color difference signal such as YCbCr, the video signal is converted into G, R, and B signals by performing a predetermined matrix operation.

  The video signals converted into G, R, and B signals are supplied to APL (Average Peak Level) detection units 203, 204, and 205 for each video color signal. The APL detection units 203 to 205 are detection means for detecting (calculating) the average value of the brightness of the input video color signal in a predetermined calculation period. The APL detection period setting unit 206 sets a period for calculating the APL in the APL detection units 203, 204, and 205. The adjustment amount calculation units 207, 208, and 209 are acquisition units that acquire the adjustment amount of the light amount based on the detection result (that is, APL) of each detection unit and a preset relationship for each color light. The acquisition means acquires the light amount adjustment amount by calculation if the relation is a mathematical expression, but acquires the reference by referring to these when the relation is the graph or table shown in FIG.

  By arbitrarily setting the APL detection period, it is possible to change the response time of the light amount adjustment. For example, if the calculation period is set to one frame and light amount adjustment is performed for each frame, the followability can be improved, and quick light amount adjustment can be performed for a video signal that changes rapidly from a bright scene to a dark scene. Become. In addition, if the calculation period is longer than one frame, the change in the amount of light can be moderated, and the unnatural change in the amount of light in a short time can be reduced in a video signal in which a bright scene and a dark scene change rapidly. it can. Thus, by arbitrarily setting the period for calculating APL, it is possible to adjust the amount of light according to the user's preference.

  FIG. 3 is a graph showing the relationship between the APL detection amount and the light amount adjustment amount. When the APL is 0, the light amount adjustment amount is 0. When the APL is the maximum, the light amount adjustment amount is 100, and the light amount adjustment amount is calculated so that the intermediate region is linear. The light amount adjustment amount for each video signal calculated by the adjustment amount calculation units 207, 208, and 209 is supplied to the light amount adjustment units 105, 106, and 107 provided for the respective video color signals.

  Conventionally, only one light amount adjusting unit is provided between the light source 101 and the dichroic mirror 102 or between the X prism 114 and the projection lens 115. For example, when an optical aperture is provided between the light source 101 and the dichroic mirror 102, there is leakage light of the RB component even if the RB color light is cut off and only the G color light is output. descend. Further, when it is desired to increase the level of G color light and decrease the level of RB color light, the aperture according to the level of G color light is not optimal for the level of RB color light. Also in this case, the color purity of G decreases.

  On the other hand, according to the present embodiment, the light amount adjustment amount is calculated for each video color signal, and the light amount adjustment is performed for each video color signal, so that appropriate light amount adjustment can be performed for each video color signal. It becomes. For example, when a video signal having a large proportion of a specific color is input, the light amount of the color component that is not used is set to 0, and leakage light from the liquid crystal panel element is reduced or blocked, thereby reducing the color light used. Color purity can be improved and color reproducibility can be improved.

  FIG. 4 is an optical path diagram of the liquid crystal projector of the second embodiment. The liquid crystal projector includes a light source 401, a dichroic mirror 402, light amount adjustment units 403 and 404, polarization beam splitters (PBS) 405, 406, and 407, liquid crystal panel elements 408, 409, and 410, and a projection lens 411. Have.

  The light source 401 is a light source that outputs white light, and is similar to the light source 101. As in the first embodiment, white light from the light source 401 is separated into G color light and RB color light by a dichroic mirror (color separation means) 402 and supplied to light quantity adjustment units (light quantity adjustment means) 403 and 404, respectively. The light amount adjustment unit 403 adjusts the light amount of G color light, and the light amount adjustment unit 404 adjusts the light amount of RB color light between 0% and 100%, respectively.

  The G color light whose light amount is adjusted by the light amount adjusting unit 403 is reflected by the PBS 405 and enters the liquid crystal panel element 408. The R color light whose light amount is adjusted by the light amount adjusting unit 404 is reflected by the PBS 406 and enters the liquid crystal panel element 409. The B color light whose light amount has been adjusted by the light amount adjusting unit 404 passes through the PBS 406 and is supplied to the liquid crystal panel element 410. Note that the R color light is S-polarized light and the B color light is P-polarized light before entering the PBS 406. This can be realized by using a color-selective phase difference plate (not shown). . The PBS 406 functions as color separation means for separating R color light and B color light.

  The light amount adjustment units 403 and 404 are disposed on the optical path between the dichroic mirror 402 and the PBS 407. More specifically, the light amount adjusting unit 403 may be disposed at an appropriate position on the optical path between the dichroic mirror 402 and the PBS 405, between the PBS 405 and the liquid crystal panel element 408, and between the PBSs 405 and 407. The light amount adjusting unit 404 may be disposed at an appropriate position in the optical path between the dichroic mirror 402 and the PBS 406 and between the PBS 406 and 407.

  The polarization of the G, R, and B color lights is controlled by the respective liquid crystal panel elements in accordance with the input video signal, and then returns to the PBS again, and the color light supplied to the PBS 407 as the projection light according to the polarization state returns to the light source direction. Separated into light components. The PBS 407 functions as a combining unit that combines G, R, and B color lights, and supplies the combined light to the projection lens 411. The projection lens 411 projects the supplied combined light onto a projection surface such as a screen and displays an image.

  FIG. 5 is a block diagram of the light quantity control system of this embodiment. The light amount control system includes a video signal input unit 501, a matrix calculation unit 502, histogram detection units 503, 504, and 505, a histogram detection period setting unit 506, and adjustment amount calculation units 507, 508, 509, and 510.

  A video signal is input to the video signal input unit 501. The matrix calculation unit 502 performs matrix calculation and converts the video signal into G, R, and B signals from the color format of the input video signal. The video signals converted into G, R, and B signals are supplied to the histogram detection units 503, 504, and 505 for each video color signal.

  Histogram detection units 503, 504, and 505 are detection means for detecting (calculating) the histogram of the input video color signal in a predetermined calculation period, and are for G, R, and B, respectively. The histogram shows the relationship of the number of image data to the gradation value for each color light.

  For example, many low-gradation images, a few high-gradation images, and almost half-tone images have the same APL and are difficult to discriminate, but can be discriminated using a histogram. The histogram detection period setting unit 506 arbitrarily sets a period for calculating the histogram in the histogram detection units 503, 504, and 505.

  By arbitrarily setting the histogram detection period, the response time of the light amount control can be changed. For example, if the calculation period is set to one frame and light amount adjustment is performed for each frame, the followability can be improved, and quick light amount adjustment can be performed for a video signal that changes rapidly from a bright scene to a dark scene. . In addition, if the calculation period is longer than one frame, the change in the amount of light can be moderated, and the unnatural change in the amount of light in a short time can be reduced in a video signal in which a bright scene and a dark scene change rapidly. it can. In this way, by arbitrarily setting the period for calculating the histogram, the light amount can be adjusted according to the user's preference.

  The histogram calculated for each video color signal is supplied to each of the adjustment amount calculation units 507, 508, and 509. The adjustment amount calculation units 507, 508, and 509 are acquisition units that acquire the adjustment amount of the light amount based on the detection result (that is, the histogram) of each detection unit and a preset relationship for each color light. The acquisition unit acquires the adjustment amount of the light amount by calculation if the relationship is a mathematical expression. If the relationship is a graph or a table shown in FIG. The adjustment amount calculation units 507, 508, and 509 are for G, R, and B, respectively.

  As an example of the light amount adjustment amount, as shown in FIG. 6, when the low gradation ratio is large due to the distribution ratio of the low gradation and the high gradation from the distribution state of the histogram, the light amount adjustment amount is brought close to 0, When the ratio is large, the light amount adjustment amount is brought close to 100.

  Since the present embodiment uses the common light amount adjustment unit 404 for the R and B color lights, the adjustment amount calculation unit 510 uses the adjustment amount calculation units 508 and 509 to calculate the R and B color lights. An average value of the light amount adjustment amount is calculated and converted to an R + B light amount adjustment amount. The adjustment amount calculated by the G adjustment amount calculation unit 507 is set in the G light amount adjustment unit 403, and the light amount adjustment amount calculated by the R + B adjustment amount calculation unit 510 is set in the light amount adjustment unit. The light amount adjusting units 403 and 404 adjust the light amount in the range of 0% to 100% according to the set light amount adjustment amount.

  By calculating the light amount adjustment amount using a histogram, it is possible to set an appropriate light amount control amount even for an image that is difficult to discriminate with APL. Also in this embodiment, the color purity can be increased as compared with the conventional liquid crystal projector having only one light amount adjusting unit.

  If there are at least two (that is, a plurality of) light quantity adjusting units between the dichroic mirror 102 and the X prism 114 or PBS 407 serving as a combining means, the color purity can be improved.

  As mentioned above, although this embodiment was described, this invention is not limited to this embodiment, A various deformation | transformation and change are possible within the range of the summary.

  The projection display device can be applied to a liquid crystal projector.

102, 103, 402 ... Dichroic mirror (color separation means), 114 ... X prism (combination means), 407 ... Polarization beam splitter (synthesis means), 105-107, 403, 404 ... Light quantity adjustment unit (light quantity adjustment means)

Claims (5)

Color separation means for separating light from the light source into a plurality of color lights;
A synthesizing means for synthesizing the three color lights modulated in accordance with the video signal;
A plurality of light quantity adjusting means for adjusting the light quantity of the plurality of color lights provided in each optical path of the plurality of color lights separated by the color separation means between the color separation means and the combining means;
A projection type display device comprising: The color separation means separates the light from the light source into first color light, second color light and third color light combined light,
2. The projection display device according to claim 1, wherein the light amount adjusting unit is provided one for each of an optical path of the first color light and an optical path of the combined light. The color separation means is a first color separation means for separating the light from the light source into a first color light, a combined light of a second color light and a third color light, and the combined light is the second color light. Color light and second color separation means for separating into the third color light,
2. The projection type according to claim 1, wherein the light amount adjusting unit is provided one for each of an optical path of the first color light, an optical path of the second color light, and an optical path of the third color light. Display device. Detection means for detecting the average brightness of each color light;
An acquisition means for acquiring an adjustment amount of the light amount of each color light based on a detection result of the detection means and a set relationship;
Have
4. The projection display device according to claim 1, wherein the light amount adjustment unit performs light amount adjustment according to the adjustment amount of the light amount acquired by the acquisition unit. 5. Detection means for detecting a histogram indicating the relationship of the number of image data to the gradation value for each color light;
An acquisition means for acquiring an adjustment amount of the light amount of each color light based on a detection result of the detection means and a set relationship;
Have
4. The projection display device according to claim 1, wherein the light amount adjustment unit performs light amount adjustment according to the adjustment amount of the light amount acquired by the acquisition unit. 5.

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