JP2011150222A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device which allows cooling such that an optical element which is an object element of cooling is set to a desired temperature, and allows efficient cooling and reduction of display unevenness. <P>SOLUTION: The image display device includes a light source that emits an illumination light; a liquid crystal display panel 19, that constitutes an optical modulation element modulating the illumination light emitted from the light source, according to an image signal; a display information processing section 42, that performs light control processing for adjusting the quantity of the illuminating light made incident on the optical modulation element, and extension processing of the image signal, corresponding to the light control processing by analyzing the image signal; and a cooling mechanism 31, that supplies cooling air to the optical element which is the element of object of cooling. The speed of the cooling air to be supplied to the optical element is controlled, according to the quantity of the illuminating light, adjusted by the light control processing in the display information processing section 42. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image display device, and more particularly to an image display device capable of adjusting the amount of illumination light supplied to a light modulation element.

  Conventionally, a projector including a cooling mechanism for cooling a light modulation element is known. For example, when the light modulation element of the projector includes a liquid crystal display panel and a polarizing plate provided so as to face the liquid crystal display panel, the liquid crystal display panel is used to reduce the variation in phase difference due to thermal contraction of the polarizing film. A technique for cooling a polarizing plate on which transmitted light is incident so as to have a substantially constant temperature has been proposed. As a result, display unevenness due to variations in phase difference is reduced. As a first method for making the polarizing plate substantially constant, for example, as proposed in Patent Document 1, a method of controlling the rotation of a fan by a black signal or a luminance level included in an image signal is known. . As a second method, as proposed in Patent Document 2, in a projector including a plurality of light sources, a method of controlling a cooling mechanism according to the number of light sources to be lit is known.

  As a projector, for example, as proposed in Patent Document 3, a projector with a so-called adaptive dimming function that adjusts the amount of illumination light incident on a light modulation element according to an image signal is known. Adaptive dimming reduces the amount of illumination light in a scene where the entire screen is dark, for example. By reducing the amount of illumination light and extending the image signal, it is possible to enhance the contrast, clearly express the image of the dark scene, and improve the dynamic contrast with the bright scene. .

JP 2001-92015 A JP 2006-343365 A JP-A-2005-55760

  For a projector with an adaptive dimming function, if the cooling mechanism is controlled only by the luminance signal as in the first method, for example, the fan speed may increase even if the illumination light quantity is reduced. It is a problem that it may occur and cause overcooling. Even in the case of using a plurality of light sources, the amount of illumination light greatly affects the temperature of the polarizing plate. Therefore, even if the second method is adopted, the temperature of the polarizing plate can be controlled. The challenge is that it can be difficult. The present invention has been made in view of the above-described problems, and enables cooling so that an optical element that is a cooling target element has a desired temperature, thereby enabling efficient cooling and reduction of display unevenness. An object is to provide an image display device.

  In order to solve the above-described problems and achieve the object, an image display device according to the present invention includes a light source that emits illumination light, and light modulation that modulates the illumination light emitted from the light source according to an image signal. A light control process for adjusting the amount of the illumination light incident on the light modulation element by analyzing the element and the image signal, and a process for expanding the image signal in accordance with the light control process A display information processing unit and a cooling mechanism that supplies cooling air to the optical element that is a cooling target element, and the speed of the cooling air supplied to the optical element is adjusted by the display information processing unit. It is controlled according to the light quantity of the illumination light adjusted by light processing.

  By controlling the wind speed of the cooling air according to the amount of illumination light obtained by analyzing the image signal, it is possible to cool the optical element so as to be substantially constant at a desired temperature. By enabling cooling at an intensity suitable for the optical element, display unevenness due to heat shrinkage and the like can be reduced, and efficient cooling can be achieved by reducing overcooling. This makes it possible to efficiently cool and reduce display unevenness.

  As a preferred aspect of the present invention, it is desirable that the wind speed of the cooling air supplied to the optical element is further controlled according to the image signal analyzed by the display information processing unit. For example, when the optical element is a light modulation element including a liquid crystal display panel and a polarizing plate provided so as to face the liquid crystal display panel, the light modulation element even if the amount of illumination light incident on the light modulation element is the same As the amount of light shielded (absorbed) by the exit side polarizing plate increases, the amount of heat generated increases. The amount of heat generated in this way is determined according to the analysis of the image signal in the display information processing unit, and the temperature of the optical element can be made more constant by controlling the wind speed of the cooling air.

  As a preferred aspect of the present invention, it is desirable that the wind speed is controlled in accordance with a histogram of luminance values that have undergone the expansion processing in the display information processing unit. Thereby, the wind speed of the cooling air is controlled according to the image signal.

  As a preferred aspect of the present invention, it is desirable that the cooling mechanism includes a fan that sends out the cooling air, and the display information processing unit generates a cooling drive signal for controlling driving of the fan. . Thereby, the air volume of the cooling air is controlled according to the illumination light quantity or according to the illumination light quantity and the image signal. Further, by controlling the number of rotations of the fan, power consumption can be reduced according to the cooling intensity.

  Moreover, as a preferred aspect of the present invention, the cooling mechanism includes a fan that sends out the cooling air, and a duct that passes the cooling air sent from the fan and supplies the cooling air to the optical element, The duct preferably includes an adjustment mechanism capable of adjusting the wind speed of the cooling air passing therethrough, and the display information processing unit preferably generates a cooling drive signal for controlling the adjustment mechanism. Thereby, the air volume of the cooling air is controlled according to the illumination light quantity or according to the illumination light quantity and the image signal. Since the fan drive sound is constant, video viewing in a stable acoustic environment is possible.

  Moreover, as a preferable aspect of the present invention, it is desirable that the wind speed adjusting mechanism changes an opening area of the cooling air outlet. Thereby, the wind speed of the cooling wind which passes a blower outlet is adjusted.

  As a preferred aspect of the present invention, it is desirable that the wind speed adjusting mechanism includes an openable / closable opening / closing part, and the opening / closing part is provided on a side wall of the duct. Thereby, the air volume of the cooling air to be advanced toward the optical element is adjusted.

  As a preferred aspect of the present invention, it is desirable that the wind speed adjusting mechanism includes a shielding part capable of changing a shielding amount of the cooling air, and the shielding part is provided inside the duct. Thereby, the air volume of the cooling air passing through the inside of the duct is adjusted.

  Moreover, as a preferable aspect of the present invention, it is preferable that the optical element that is the element to be cooled includes a polarizing plate constituting the light modulation element. Thereby, the dispersion | variation in the phase difference by the heat shrink of a polarizing film is reduced, and a display nonuniformity is reduced.

  Moreover, as a preferable aspect of the present invention, the light source is provided for each color light, and the air velocity of the cooling air supplied to the optical element is controlled for each color light adjusted by the light control processing. Is desirable. By providing a light source for each color light, it is possible to adjust the amount of light for each color light. By making it possible to control the speed of the cooling air for each color light adjusted by the light control processing, the optical element can be cooled with an optimum intensity for each color light.

1 is a diagram illustrating a schematic configuration of a projector according to Embodiment 1. FIG. The schematic diagram which shows the cross-sectional structural example of a projector. The block diagram which shows the structure for control, such as a liquid crystal display panel. The graph showing the 1st example of the appearance amount distribution of the luminance value before an expansion | extension process. The graph explaining the process example of the display information processing part in a 1st example. The graph showing the 2nd example of the appearance amount distribution of the luminance value before an expansion | extension process. The graph explaining the process example of the display information processing part in a 2nd example. The graph showing the 3rd example of the appearance amount distribution of the luminance value before an expansion | extension process. The graph explaining the process example of the display information processing part in a 3rd example. The graph showing the 4th example of the appearance amount distribution of the luminance value before an expansion | extension process. The graph explaining the process example of the display information processing part in a 4th example. FIG. 6 is a schematic diagram illustrating a cross-sectional configuration example of a projector according to a modification of the first embodiment. FIG. 6 is a diagram illustrating a projector according to a second embodiment. FIG. 6 is a diagram for explaining a first modification of the second embodiment. FIG. 6 is a schematic cross-sectional view of a projector according to a second modification of the second embodiment (part 1). FIG. 10 is a schematic cross-sectional view of a projector according to a second modification of the second embodiment (part 2). FIG. 6 is a diagram illustrating a schematic configuration of a projector according to a third embodiment. The block diagram which shows the structure for control, such as a liquid crystal display panel.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of a projector 1 that is an image display device according to a first embodiment of the invention. The light source 10 is an ultra-high pressure mercury lamp, for example, and emits illumination light including red (R) light, green (G) light, and blue (B) light. The first integrator lens 11 and the second integrator lens 12 have a plurality of lens elements arranged in an array. The first integrator lens 11 splits the light flux from the light source 10 into a plurality of parts. Each lens element of the first integrator lens 11 condenses the light beam from the light source 10 in the vicinity of the lens element of the second integrator lens 12. The lens element of the second integrator lens 12 forms an image of the lens element of the first integrator lens 11 on the liquid crystal display panels 19R, 19G, and 19B.

  The polarization conversion element 13 converts light from the second integrator lens 12 into predetermined linearly polarized light, for example, s-polarized light. The illumination light quantity adjusting device 14 adjusts the quantity of illumination light incident from the polarization conversion element 13. The illumination light amount adjusting device 14 includes, for example, a diaphragm mechanism that can mechanically adjust the light amount, a light source driving circuit that can adjust the power supplied to the light source 10, an electrochromic glass that can electrically adjust the transmitted light amount, and the like. Any device capable of adjusting the amount of light may be used. In the present embodiment, the illumination light amount adjusting device 14 adjusts the illumination light amount supplied to the liquid crystal display panels 19R, 19G, and 19B from, for example, 100% to 0%.

  The first dichroic mirror 15 transmits R light and reflects G light and B light among the illumination light whose light amount is adjusted by the illumination light amount adjusting device 14. The R light transmitted through the first dichroic mirror 15 is reflected by the reflection mirror 17 and converted to p-polarized light by a half-wave plate (not shown). The incident side polarizing plate 18 transmits p-polarized light. The liquid crystal display panel 19R converts p-polarized light into s-polarized light according to the image signal. The exit side polarizing plate 20 transmits the s-polarized light from the liquid crystal display panel 19R. The incident-side polarizing plate 18, the liquid crystal display panel 19R, and the emission-side polarizing plate 20 function as a light modulation element that modulates R light according to an image signal.

  The second dichroic mirror 16 reflects the G light from the first dichroic mirror 15 and transmits the B light. The G light reflected by the second dichroic mirror 16 enters the liquid crystal display panel 19G via the incident side polarizing plate 18 that transmits the s-polarized light. The liquid crystal display panel 19G converts s-polarized light into p-polarized light according to the image signal. The exit side polarizing plate 20 transmits the p-polarized light from the liquid crystal display panel 19G. The incident-side polarizing plate 18, the liquid crystal display panel 19G, and the emission-side polarizing plate 20 function as a light modulation element that modulates the G light according to an image signal.

  The B light transmitted through the second dichroic mirror 16 passes through relay lenses 22 and 24 and reflection mirrors 23 and 25 and is converted to p-polarized light by a half-wave plate (not shown). The incident side polarizing plate 18 transmits p-polarized light. The liquid crystal display panel 19B converts p-polarized light into s-polarized light according to the image signal. The exit side polarizing plate 20 transmits the s-polarized light from the liquid crystal display panel 19B. The incident-side polarizing plate 18, the liquid crystal display panel 19B, and the emission-side polarizing plate 20 function as a light modulation element that modulates B light according to an image signal. The cross dichroic prism 21 which is a color synthesis optical system synthesizes each color light transmitted through the exit side polarizing plate 20. The projection lens 26 projects the light combined by the cross dichroic prism 21 onto the screen 27.

  FIG. 2 is a schematic diagram illustrating a cross-sectional configuration example of the projector 1. Here, a part of the projector 1 shown in FIG. 1 is shown and described, and illustration of elements unnecessary for the description is omitted. In the figure, white arrows represent main directions in which cooling air flows.

  In the configuration shown in the drawing, the light source 10, the polarization conversion element 13, the incident side polarizing plate 18, the liquid crystal display panel 19 (19R, 19G, 19B) and the emission side polarizing plate 20 are main optical elements that are elements to be cooled. . The first cooling mechanism 31 supplies cooling air to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. The first cooling mechanism 31 includes a fan 34 and a duct 35. The fan 34 sends out cooling air. The duct 35 passes the cooling air sent from the fan 34 and supplies it to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. The first cooling mechanism 31 is provided for each color light.

  The second cooling mechanism 32 supplies cooling air to the polarization conversion element 13. The second cooling mechanism 32 includes a fan 34 and a duct 35 that passes cooling air and supplies it to the polarization conversion element 13. The third cooling mechanism 33 is a fan that sends cooling air to the light source 10.

  FIG. 3 is a block diagram illustrating a configuration for controlling the liquid crystal display panel 19, the first cooling mechanism 31, and the illumination light amount adjusting device 14. The display information input unit 41 receives an image signal. The display information processing unit 42 analyzes the image signal input to the display information input unit 41, and generates a display drive signal, a light amount adjustment signal, and a cooling drive signal. The R light display drive unit 43R drives the R light liquid crystal display panel 19R according to the display drive signal from the display information processing unit 42. The G light display drive unit 43G drives the G light liquid crystal display panel 19G in accordance with the display drive signal from the display information processing unit 42. The B light display drive unit 43B drives the B light liquid crystal display panel 19B in accordance with the display drive signal from the display information processing unit 42.

  The illumination light amount adjustment drive unit 45 drives the illumination light amount adjustment device 14 in accordance with the light amount adjustment signal from the display information processing unit 42. When the illumination light amount adjusting device 14 is an aperture mechanism, the illumination light amount adjustment drive unit 45 operates the aperture mechanism to adjust the size of the aperture. When the illumination light quantity adjusting device 14 is electrochromic glass, the illumination light quantity adjustment driving unit 45 adjusts the transmitted light quantity by changing the voltage applied to the electrochromic glass.

  The cooling mechanism drive unit 44 responds to the cooling drive signal from the display information processing unit 42 in accordance with the first cooling mechanism 31 (first cooling mechanism 31R for R light, first cooling mechanism 31G for G light, and for B light). The first cooling mechanism 31B) is driven. By driving the fan 34 of the first cooling mechanism 31 at a rotation speed corresponding to the cooling drive signal, the wind speed of the cooling air, that is, the air volume of the cooling air supplied to the element to be cooled per unit time is controlled.

  4 to 11 are diagrams for explaining the light control processing and the expansion processing by the display information processing unit 42. Based on the analysis of the image signal, the projector 1 performs adaptive dimming that increases the illumination light amount for a bright scene image and decreases the illumination light amount for a dark scene image. The display information processing unit 42 determines the luminance value of the display drive signal based on the image signal input from the display information input unit 41.

  FIG. 4 is a graph showing a first example of an appearance amount distribution (histogram) of luminance values before image signal decompression processing. The horizontal axis of the graph represents the luminance value of the image signal, and the vertical axis represents the number of pixels. i (max) is the maximum luminance value of the image signal. In the first example, the luminance values i1 to i2 of the image signal are distributed in a range of values not more than half of the maximum value i (max). The distribution shown in FIG. 4 represents a dark scene in which the entire video is about half or less of the maximum luminance. The histogram of luminance values is obtained by analyzing the image signal in the display information processing unit 42.

  FIG. 5 is a graph for explaining a processing example of the display information processing unit 42 in the first example. The horizontal axis of the graph represents the luminance value of the display drive signal, and the vertical axis represents the amount of light output from the liquid crystal display panel 19. In the first example, the display information processing unit 42 outputs a light amount adjustment signal that reduces the illumination light amount to about half of the maximum value by performing the dimming process.

  The display information processing unit 42 performs an image signal expansion process corresponding to the light control process. In this example, the display information processing unit 42 outputs a display drive signal that extends the dynamic range of the luminance value to i′1 to i′2 that is about twice as large as i1 to i2. The number of gradations that can be expressed is increased without changing the output light amounts o1 to o2, by reducing the illumination light amount and performing the image signal expansion process. As a result, it is possible to enhance contrast in a dark scene and express an image clearly, and to improve dynamic contrast with a bright scene. Moreover, since the light quantity shielded (absorbed) by the exit side polarizing plate 20 can be reduced as described later, the amount of heat generated by the exit side polarizing plate 20 can be reduced.

  The display information processing unit 42 controls the wind speed of the cooling air from the first cooling mechanism 31 according to the amount of illumination light adjusted by the light control process and the histogram of the luminance value that has undergone the extension process. In this example, the display information processing unit 42 performs control to reduce the wind speed with respect to the maximum wind speed in response to halving the illumination light amount from the maximum value by the dimming process. Further, since the display information processing unit 42 can reduce the amount of heat generated in the exit-side polarizing plate 20 by the image signal expansion process, the display information processing unit 42 performs control to further reduce the wind speed according to the expansion process performed by the analysis of the image signal. I do.

  FIG. 6 is a graph showing a second example of the appearance amount distribution (histogram) of luminance values before the image signal decompression processing. The second example is an example in which the luminance values i1 to i2 of the image signal are bisected and distributed so that most of the video is dark at about half or less of the maximum luminance and part of the video is bright including the maximum luminance. It is.

  FIG. 7 is a graph illustrating a processing example of the display information processing unit 42 in the second example. In the second example, since the maximum luminance is included in the video, the display information processing unit 42 outputs a light amount adjustment signal that keeps the illumination light amount at the maximum value without performing the dimming process for reducing the illumination light amount. . Since the dimming process is not performed, the display information processing unit 42 does not perform the image signal expansion process, and the display drive signal sets the dynamic range of the luminance value to i′1 to i′2 that is the same as i1 to i2. Is output.

  In general, when the light modulation element includes a liquid crystal display panel and an absorption-type polarizing plate, even when the amount of light incident on the light modulation element is constant, the displayed image is shielded by the polarizing plate on the emission side ( The amount of light absorbed is increased. As a result, the amount of heat absorbed by the exit-side polarizer increases, and the temperature of the exit-side polarizer increases. On the other hand, if the displayed image is bright, the amount of light absorbed by the exit-side polarizing plate is small because the amount of light shielded (absorbed) by the exit-side polarizing plate is small, and the temperature of the exit-side polarizing plate is Lower.

  In the case of the second example, the illumination light amount is kept at the maximum value, and most of the histogram is distributed to half or less of the maximum value i (max). Become. In such a situation, the display information processing unit 42 performs control to increase the speed of the cooling air from the first cooling mechanism 31 as compared with the case of the first example. The display information processing unit 42 increases the wind speed of the cooling air as the illumination light amount is higher and the histogram is biased toward a lower luminance range. Thereby, the amount of heat generated in the exit-side polarizing plate 20 can be reduced.

  FIG. 8 is a graph showing a third example of luminance value appearance amount distribution (histogram) before image signal decompression processing. In the third example, the luminance values i1 to i2 of the image signal include the maximum value i (max), and most of the luminance values are distributed in half or more of the maximum value i (max). The distribution shown in FIG. 8 represents a bright scene in which the entire video is about half or more of the maximum luminance.

  FIG. 9 is a graph for explaining a processing example of the display information processing unit 42 in the third example. In the third example, since the maximum luminance is included in the video, the display information processing unit 42 outputs a light amount adjustment signal that keeps the illumination light amount at the maximum value without performing the dimming process for reducing the illumination light amount. . Since the dimming process is not performed, the display information processing unit 42 does not perform the image signal expansion process, and the display drive signal sets the dynamic range of the luminance value to i′1 to i′2 that is the same as i1 to i2. Is output.

  In the case of the third example, since most of the histogram is distributed over half of the maximum value i (max), the histogram is shielded (absorbed) by the emission side polarizing plate 20 as compared with the case of the second example. The amount of light is small and the amount of heat generated is low. In such a situation, the display information processing unit 42 performs control to lower the wind speed of the cooling air from the first cooling mechanism 31 compared to the case of the second example. The display information processing unit 42 lowers the cooling air velocity as the histogram is biased toward a higher luminance range. Thereby, the overcooling of the exit side polarizing plate 20 can be reduced.

  FIG. 10 is a graph showing a fourth example of the appearance amount distribution (histogram) of luminance values before the image signal expansion processing. The fourth example is a histogram close to the third example, but is an example in which the luminance value i2 of the image signal is lower than the maximum value i (max).

  FIG. 11 is a graph illustrating a processing example of the display information processing unit 42 in the fourth example. Since the fourth example is a histogram up to a luminance slightly lower than the maximum luminance, the display information processing unit 42 performs a dimming process that slightly reduces the amount of illumination light. Further, the display information processing unit 42 outputs a display drive signal that slightly expands the dynamic range of the luminance value from i1 to i2 to i'1 to i'2. The display information processing unit 42 slightly reduces the air velocity of the cooling air by slightly reducing the amount of illumination light from the maximum value by dimming processing and slightly expanding the image signal as compared with the case of the third example. Take control.

  As described above, the display information processing unit 42 adjusts the wind speed of the cooling air according to the level of the illumination light amount after the dimming process and the luminance value histogram after the extension process. The wind speed of the cooling air supplied to the optical element is controlled in accordance with the amount of illumination light adjusted by the dimming process in the display information processing unit 42 and the histogram of the luminance values after the extension process. The projector 1 can cool the optical element so as to be substantially constant at a desired temperature by adjusting the amount of cooling air by the display information processing unit 42. By enabling cooling at an intensity suitable for the optical element, display unevenness due to heat shrinkage and the like can be reduced, and efficient cooling can be achieved by reducing overcooling. In the present embodiment, by providing the first cooling mechanism 31 (31R, 31G, 31B) for each color light, the optical element can be cooled with an optimum intensity for each color light. Further, by controlling the rotation speed of the fan 34, the power consumption can be reduced according to the cooling intensity.

  FIG. 12 is a schematic diagram illustrating a cross-sectional configuration example of the projector 1 according to a modification of the present embodiment. In this modification, the cooling mechanism 50 includes a fan 51, a main duct 52, a liquid crystal display panel / polarizing plate duct 53, and a polarization conversion element duct 54. The main duct 52 allows the cooling air sent from the fan 51 to pass through. The liquid crystal display panel / polarizing plate duct 53 branches a part of the cooling air passing through the main duct 52 and supplies the branched air to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. The polarization conversion element duct 54 supplies the cooling air that has passed through the main duct 52 to the polarization conversion element 13. In this modification, cooling air is supplied from the common fan 51 to the polarization conversion element 13, the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20.

  In this modification, the display information processing unit 42 determines the color light that needs the strongest cooling among the respective color lights based on the analysis of the image signal, and the cooling air flow so that the optical element of the color light has a desired temperature. Adjust the wind speed. In the case of this modification as well, the optical element can be cooled with an optimum intensity corresponding to the amount of illumination light.

  FIG. 13 is a diagram illustrating the projector according to the second embodiment of the invention. The present embodiment is characterized in that the wind speed of the cooling air is adjusted by the control of the adjusting mechanism. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The cooling mechanism 60 supplies cooling air to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. The cooling mechanism 60 includes a fan 34 and a duct 61. The duct 61 passes the cooling air sent from the fan 34 and supplies it to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. The cooling mechanism 60 is provided for each color light.

  The duct 61 includes a movable part capable of changing the opening area of the cooling air outlet 62. Such a movable part functions as a wind speed adjusting mechanism capable of adjusting the wind speed of the cooling air ejected from the air outlet 62. On the right side in FIG. 13, a cross-sectional configuration of the cooling mechanism 60 when the opening area of the air outlet 62 is maximum and an upper surface configuration of the duct 61 viewed from the air outlet 62 side are shown. On the left side in FIG. 13, a cross-sectional configuration of the cooling mechanism 60 when the opening area of the air outlet 62 is minimum and an upper surface configuration of the duct 61 viewed from the air outlet 62 side are shown. The cooling mechanism 60 has a cross-sectional configuration along the traveling direction of the cooling air.

  For example, in the state shown on the left side in FIG. 13, the duct 61 has a shape that is gradually narrowed from the fan 34 side toward the air outlet 62 side. On the other hand, in the state shown on the right side in FIG. 13, the duct 61 has a shape that is slightly expanded from the fan 34 side toward the air outlet 62 side. The duct 61 is configured to be appropriately deformable between a state where the opening area of the air outlet 62 is maximum and a state where the opening area is minimum.

  The cooling mechanism 60 reduces the cooling air speed by widening the opening area of the air outlet 62 while keeping the rotation speed of the fan 34 constant, and makes the cooling air speed high by narrowing the opening area of the air outlet 62. The display information processing unit 42 (see FIG. 3) generates a cooling drive signal for controlling the adjusting mechanism of the cooling mechanism 60. The wind speed of the cooling air is controlled by driving the air volume adjusting mechanism so that the air outlet 62 has an opening area corresponding to the cooling drive signal.

  Also in this embodiment, it is possible to perform cooling so that the optical element that is a cooling target element has a desired temperature, and it is possible to efficiently cool and reduce display unevenness. Further, in this embodiment, it is possible to adjust the speed of the cooling air while keeping the rotation speed of the fan 34 constant. By making the rotation speed of the fan 34 constant and reducing the change in driving sound, it is possible to view images in a stable acoustic environment. A cooling mechanism capable of stabilizing the acoustic environment is useful when, for example, a projector is applied to a home theater or the like. In addition, the adjustment mechanism should just be able to change the opening area of the blower outlet 62, and is not restricted to the case where the duct 61 is deform | transformed by the aspect demonstrated in a present Example.

  FIG. 14 is a diagram illustrating a first modification of the present embodiment. This modification includes an opening / closing part 67 that can be opened and closed. The opening / closing part 67 is provided on the side wall of the duct 66 and functions as a wind speed adjusting mechanism. For example, in the state shown on the right side in FIG. 14, the two opening / closing parts 67 are opened. At this time, the cooling air that has passed through the opening / closing portion 67 travels in a direction other than the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20. On the other hand, in the state shown on the left side in FIG. The cooling mechanism 65 opens the opening / closing part 67 while keeping the rotation speed of the fan 34 constant, thereby lowering the cooling air supplied to the optical element, and closing the opening / closing part 67 to cool the cooling air supplied to the optical element. To make it faster.

  The cooling mechanism 65 controls the speed of the cooling air by adjusting the opening / closing of the opening / closing sections 67 between a state where all the opening / closing sections 67 are fully opened and a state where all the opening / closing sections 67 are closed. The air velocity of the cooling air is controlled by adjusting at least one of the number of opening / closing portions 67 and the degree of opening. Also in this modification, by controlling the wind speed of the cooling air, it is possible to cool the optical element that is the element to be cooled to a desired temperature. Note that the number of opening / closing portions 67 provided in the duct 66 may be at least one and any number.

  15 and 16 are schematic cross-sectional views of a projector 70 according to the second modification of the present embodiment. This modification includes a shielding portion 76 that can change the shielding amount of the cooling air. The shielding part 76 is provided inside the duct and functions as an air volume adjusting mechanism. The cooling mechanism 71 includes a fan 72, a main duct 73, a liquid crystal display panel / polarizing plate duct 74, and a polarization conversion element duct 75. In this modification, cooling air is supplied from the common fan 72 to the polarization conversion element 13, the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20.

  The shielding part 76 is provided inside the main duct 73. The shielding part 76 is configured by a plate member that can rotate around a rotation axis perpendicular to the traveling direction of the cooling air. The shielding part 76 shown in FIG. 15 is disposed so that the plane of the plate member is parallel to the direction of travel of the cooling air. At this time, the shielding amount of the cooling air at the shielding portion 76 is minimized. When the shielding part 76 is rotated from the state shown in FIG. 15, the shielding part 76 is inclined with respect to the traveling direction of the cooling air, as shown in FIG. The shielding amount of the cooling air by the shielding portion 76 increases as the plane of the shielding portion 76 becomes nearly perpendicular to the traveling direction of the cooling air, and becomes maximum when the surface becomes vertical.

  The cooling mechanism 71 controls the wind speed of the cooling air by changing the inclination of the shielding part 76 with respect to the traveling direction of the cooling air. Also in this modification, by controlling the wind speed of the cooling air, it is possible to cool the optical element that is the element to be cooled to a desired temperature. In addition, the position where the shielding part 76 is provided is not limited to the illustrated position, and may be any position in the duct. Moreover, the shielding part 76 should just change the shielding amount of cooling air, and is not restricted to what rotates a board member centering on a rotating shaft. The shielding unit 76 may employ, for example, an open / close structure that opens and closes the inside of the duct, a diaphragm structure, or the like.

  FIG. 17 is a diagram illustrating a schematic configuration of a projector 80 according to the third embodiment of the invention. The projector 80 includes light sources 81R, 81G, and 81B for each color light. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The light source 81R for R light, the light source 81G for G light, and the light source 81B for B light each include a plurality of LEDs.

  FIG. 18 is a block diagram illustrating a configuration for controlling the liquid crystal display panel 19, the first cooling mechanism 31, and the illumination light amount adjustment devices 82R, 82G, and 82B. The R light illumination amount adjusting device 82R adjusts the light amount of the R light that is the illumination light emitted from the R light source 81R. The illumination light amount adjusting device 82G for G light adjusts the light amount of G light that is illumination light emitted from the light source 81G for G light. The illumination light amount adjusting device 82B for B light adjusts the light amount of B light that is illumination light emitted from the light source 81B for B light. The illumination light amount adjustment drive unit 45 drives the illumination light amount adjustment devices 82R, 82G, and 82B in accordance with the light amount adjustment signal from the display information processing unit 42.

  The projector 80 adjusts the amount of illumination light for each color light supplied from the light sources 81R, 81G, 81B. The wind speed of the cooling air supplied to the incident side polarizing plate 18, the liquid crystal display panel 19, and the emission side polarizing plate 20 is controlled for each color light adjusted by the dimming process. In this embodiment, the speed of the cooling air can be controlled for each color light adjusted by the dimming process, so that the optical element can be cooled with an optimum intensity for each color light. The light sources 81R, 81G, and 81B are not limited to those configured by LEDs, and may be configured by solid light sources other than LEDs or laser light sources, for example.

  The projector 1 is not limited to a configuration using a transmissive liquid crystal display panel as a spatial light modulator. The spatial light modulation device may use a reflective liquid crystal display (Liquid Crystal On Silicon; LCOS), DMD (Digital Micromirror Device), GLV (Grating Light Valve), or the like. Furthermore, the image display apparatus according to the present invention is not limited to a projector. The image display device may be a so-called direct-view display, for example.

  DESCRIPTION OF SYMBOLS 1 Projector, 10 Light source, 11 1st integrator lens, 12 2nd integrator lens, 13 Polarization conversion element, 14 Illumination light quantity adjustment apparatus, 15 1st dichroic mirror, 16 2nd dichroic mirror, 17, 23, 25 Reflection mirror, 18 Incident side polarizing plate, 19R, 19G, 19B, 19 Liquid crystal display panel, 20 Exit side polarizing plate, 21 Cross dichroic prism, 22, 24 Relay lens, 26 Projection lens, 27 Screen, 31, 31R, 31G, 31B First cooling Mechanism, 32 Second cooling mechanism, 33 Third cooling mechanism, 34 Fan, 35 Duct, 41 Display information input unit, 42 Display information processing unit, 43R, 43G, 43B Display drive unit, 44 Cooling mechanism drive unit, 45 Illumination light quantity Adjustment drive unit, 50 cooling mechanism, 51 52, main duct, 53 liquid crystal display panel / polarizing plate duct, 54 polarization conversion element duct, 60 cooling mechanism, 61 duct, 62 outlet, 65 cooling mechanism, 66 duct, 67 opening / closing part, 70 projector, 71 Cooling mechanism, 72 fan, 73 main duct, 74 liquid crystal display panel / polarizing plate duct, 75 polarization conversion element duct, 76 shielding unit, 80 projector, 81R, 81G, 81B light source, 82R, 82G, 82B illumination light quantity adjusting device

Claims (10)

A light source that emits illumination light;
A light modulation element that modulates the illumination light emitted from the light source according to an image signal;
Display information processing for performing dimming processing for adjusting the amount of the illumination light incident on the light modulation element by analyzing the image signal, and expansion processing for the image signal in accordance with the dimming processing And
A cooling mechanism for supplying cooling air to the optical element that is a cooling target element,
An image display device characterized in that a wind speed of the cooling air supplied to the optical element is controlled according to a light amount of the illumination light adjusted by the light control processing in the display information processing unit.   The image display apparatus according to claim 1, wherein the wind speed of the cooling air supplied to the optical element is further controlled according to the image signal analyzed by the display information processing unit.   The image display device according to claim 2, wherein the wind speed is controlled in accordance with a histogram of luminance values that have undergone the expansion processing in the display information processing unit. The cooling mechanism includes a fan that sends out the cooling air,
The image display apparatus according to claim 1, wherein the display information processing unit generates a cooling drive signal for controlling driving of the fan. The cooling mechanism is
A fan for sending out the cooling air;
A duct for passing the cooling air sent from the fan and supplying it to the optical element,
The duct includes a wind speed adjusting mechanism capable of adjusting the wind speed of the cooling air passing therethrough,
5. The image display apparatus according to claim 1, wherein the display information processing unit generates a cooling drive signal for controlling the wind speed adjusting mechanism.   The image display device according to claim 5, wherein the wind speed adjusting mechanism changes an opening area of the cooling air outlet. The wind speed adjusting mechanism includes an openable / closable opening / closing part,
The image display device according to claim 5, wherein the opening / closing portion is provided on a side wall of the duct. The wind speed adjusting mechanism includes a shielding part capable of changing a shielding amount of the cooling air,
The image display device according to claim 5, wherein the shielding portion is provided inside the duct.   The image display apparatus according to claim 1, wherein the optical element that is the element to be cooled includes a polarizing plate that forms the light modulation element. The light source is provided for each color light,
10. The image display device according to claim 1, wherein an air velocity of the cooling air supplied to the optical element is controlled for each of the color lights adjusted by the dimming process. .

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