Projection-type display device and projection-type display device control method

Abstract

To provide a projection-type display device capable of appropriately correcting a change in display luminance.SOLUTION: A re-incident illumination light intensity calculation unit 311 calculates the intensity of re-incident illumination light being first polarization light that is reflected without modulation by a reflective liquid crystal display element, returns to a light source unit 1 side, is reflected, and is re-incident on the reflective liquid crystal display element, of the first polarization light incident on the reflective liquid crystal display element in illumination light including the first polarization light and second polarization light, and calculates a total value by adding together the re-incident illumination light intensities of all the pixels constituting a frame. A reference re-incident illumination light intensity storage unit 32 stores reference total values for reference frame images from minimum gradation to maximum gradation. A light source control unit 33 selects a reference total value of any of the reference frame images, compares the calculated total value with the selected reference total value, and controls an amount of light which is emitted by a light source 11 provided in the light source unit 1.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a projection display device and a method for controlling a projection display device. [Background technology]

[0002] In a projection display device using a reflective liquid crystal display element as a light modulation element, the illumination light incident on the reflective liquid crystal display element is modulated according to an image to be displayed, and the remaining illumination light other than the modulated light reflected toward the projection lens returns to the illumination optical system or the light source unit. The illumination light that has returned to the illumination optical system or the light source unit may be reflected within the illumination optical system or the light source unit and re-enter the reflective liquid crystal display element.

[0003] The illumination light returning to the illumination optical system or the light source at a certain pixel and being reflected in the illumination optical system or the light source again enters the reflective liquid crystal display element, does not enter the same pixel but irradiates the entire reflective liquid crystal display element. Therefore, when the illumination light is again entered into the reflective liquid crystal display element, the display luminance of each pixel in each frame changes depending on the pixel value of the entire frame.

[0004] As an example, the first to third frames, each having 8-bit video data, are compared. The first frame has a gradation of 128 throughout the entire frame. The second frame has a gradation of 128 area in the center of the frame, surrounded by a gradation of 0 (black). The third frame has a gradation of 128 area in the center of the frame, surrounded by a gradation of 255 (white). In this case, the display luminance of the first frame, which has a gradation of 128, the display luminance of the gradation of 128 area of ​​the second frame, and the display luminance of the gradation of 128 area of ​​the third frame are all different because they are affected by the re-entry of illumination light to different degrees. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-118224 A Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 describes a method of adjusting the balance between red (R), green (G), and blue (B) color data in video data by multiplying the data by a gain to adjust the balance between R, G, and B in order to compensate for the effects of re-entering illumination light. However, if the pixel value of each color data is close to the maximum value, multiplying the data by the gain will make the pixel value the maximum value, causing so-called blown-out highlights. The method of multiplying color data by a gain cannot adequately correct changes in display luminance.

[0007] The present invention aims to provide a projection display device and a control method for a projection display device that can appropriately correct changes in display brightness caused by the re-entry of illumination light into a reflective liquid crystal display element. [Means for solving the problem]

[0008] The present invention calculates, for each pixel constituting a frame to be analyzed for an image among each frame of image data to be displayed on a reflective liquid crystal display element, the intensity of re-incident illumination light, which is the first polarized light, of illumination light including first and second polarized light that is incident on the reflective liquid crystal display element via a polarizing plate, is reflected without being modulated by the reflective liquid crystal display element, returns to the light source unit side of the polarizing plate, and is reflected by an optical element located on the light source unit side of the polarizing plate or the light source unit and re-incidents on the reflective liquid crystal display element via the polarizing plate, and calculates the intensity of the re-incident illumination light with respect to all pixels constituting the target frame. a reference re-incident illumination light intensity storage unit that stores a reference sum value obtained by summing up the intensities of the re-incident illumination light for each pixel when a reference frame image from a minimum gradation to a maximum gradation is displayed on the reflective liquid crystal display element; and a light source control unit that selects a reference sum value of any of the reference frame images based on the target frame, compares the sum value calculated by the re-incident illumination light intensity calculation unit with the selected reference sum value, and controls the amount of light emitted by a light source provided in the light source unit.

[0009] The present invention calculates, for each pixel constituting a frame to be analyzed for video among each frame of video data to be displayed on a reflective liquid crystal display element, the intensity of re-incident illumination light, which is the first polarized light, of illumination light including first and second polarized light that is incident on the reflective liquid crystal display element via a polarizing plate without being modulated by the reflective liquid crystal display element, is reflected back toward the light source unit side from the polarizing plate, and is reflected by an optical element located on the light source unit side from the polarizing plate or the light source unit and is re-incident on the reflective liquid crystal display element via the polarizing plate, thereby constituting the frame to be analyzed. the control method for a projection display device includes: calculating a sum value by adding up the intensities of the re-incident illumination light calculated for all pixels corresponding to the reference frame image; selecting a reference sum value of any of the reference frame images based on the target frame from among reference sum values ​​obtained by adding up the intensities of the re-incident illumination light for each pixel when reference frame images from the minimum to maximum gradations are displayed on the reflective liquid crystal display element, which are stored in a reference re-incident illumination light intensity memory unit; and comparing the calculated sum value with the selected reference sum value to control the amount of light emitted by the light source provided in the light source unit. Effect of the Invention

[0010] According to the projection display device and the control method for the projection display device of the present invention, it is possible to appropriately correct the change in display luminance caused by the re-entry of illumination light into a reflective liquid crystal display element. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a projection type display device according to an embodiment. [Diagram 2] FIG. 2 is a plan view and a side view showing a detailed configuration of a light source unit included in the projection display device according to the embodiment. [Diagram 3] FIG. 3 shows another type of reflective polarizer that can be used instead of the reflective polarizer in FIG. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of an element / light source driving section included in the projection display device according to one embodiment. [Figure 5A] FIG. 5A is a characteristic diagram showing the horizontal irradiation intensity of illumination light irradiated onto a light modulation element. [Figure 5B] FIG. 5B is a characteristic diagram showing the irradiation intensity in the vertical direction of the illumination light irradiated onto the light modulation element. [Figure 6A] FIG. 6A is a diagram showing a first delay time from the time when the frame is switched from the previous frame to the current frame until the video data of the current frame is displayed on the light modulation element, and a second delay time until the light source emits light with an amount of light corresponding to the current frame. [Figure 6B] FIG. 6B is a diagram showing how the timing of controlling a light source driver that drives a light source is delayed when the first delay time is longer than the second delay time. [Figure 6C] FIG. 6C is a diagram illustrating delaying video data when the second delay time is longer than the first delay time. [Figure 6D] FIG. 6D illustrates that the projected image on the screen is displayed with a delay that varies between a minimum delay time and a maximum delay time. [Figure 7A] FIG. 7A is a partial flowchart showing the operation of a projection display device according to an embodiment. [Figure 7B] FIG. 7B is a partial flowchart following FIG. 7A, showing the operation of a projection display device according to an embodiment. [Figure 8A] FIG. 8A is a diagram showing the amount of delay of video data caused by a delay device when the first delay time is the minimum delay time in a preferable example of the element and light source driving section. [Figure 8B] FIG. 8B is a diagram showing the amount of delay of video data by the delay device when the first delay time is an intermediate delay time between the minimum delay time and the maximum delay time in a preferable configuration example of the element and light source driving section. [Figure 8C] FIG. 8C is a diagram showing the delay amount of video data caused by the delay device when the first delay time is the maximum delay time in the preferable configuration example of the element / light source driving section. [Figure 8D]FIG. 8D is a diagram showing that in a preferred embodiment of the element and light source driving section, the projected image on the screen is displayed with a fixed delay time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a projection display device and a control method for a projection display device according to an embodiment will be described with reference to the accompanying drawings. In Fig. 1, a projection display device 100 according to an embodiment includes a light source unit 1 that emits white illumination light WiL. The light source unit 1 is configured as shown in Fig. 2. In Fig. 2, B (B1 and B2) and Y represent blue light and yellow light, respectively.

[0013] In Fig. 2, the light source unit 1 has a light source 11 consisting of multiple blue laser elements 11e, and a phosphor wheel 120. (a) in Fig. 2 is a front view of the light source unit 1, and (b) is a side view of the light source unit 1. The blue light emitted from the light source 11 is collected by the collecting lens 12 and enters the split mirror 13. The split mirror 13 transmits a portion (B1) of the incident blue light and reflects the remaining portion (B2). The blue light (B2) reflected by the split mirror 13 is reflected by mirrors 15 and 19, collected by the collecting lens 18, and reflected by the mirror 17.

[0014] The blue light (B2) reflected by mirror 17 is reflected by dichroic mirror 16. Dichroic mirror 16 has the property of reflecting blue light and transmitting yellow light.

[0015] The blue light (B1) transmitted through split mirror 13 is reflected by dichroic mirror 16, collected by collecting lenses 110 and 111, and directed toward phosphor wheel 120. Phosphor wheel 120 is configured to rotate mirror-like disk 121 around rotation axis 123 by motor 124. Phosphor 122 is applied near the outer circumferential edge of disk 121. The blue light collected by collecting lenses 110 and 111 is incident on phosphor 122, exciting it to emit yellow light containing red and green components.

[0016] The yellow light emitted from phosphor 122 is incident on dichroic mirror 16 via condenser lenses 111 and 110. Dichroic mirror 16 transmits the yellow light. As described above, the blue light (B2) reflected by dichroic mirror 16 and the yellow light transmitted through dichroic mirror 16 are emitted from light source unit 1 as white illumination light WiL.

[0017] Returning to Fig. 1, illumination light WiL emitted from the light source unit 1 is reflected by the mirror 2 and enters the fly-eye lenses 3a and 3b. The optical elements from the mirror 2 to just before the red (R), green (G), and blue (B) light modulation elements 10R, 10G, and 10B described below constitute the illumination optical system. The R, G, and B light modulation elements 10R, 10G, and 10B will be referred to as the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B, respectively. The R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B may be collectively referred to as the light modulation element 10.

[0018] The R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B are reflective liquid crystal display elements. That is, the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B are a red reflective liquid crystal display element, a green reflective liquid crystal display element, and a blue reflective liquid crystal display element, respectively. The R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B may be liquid crystal display elements generally called LCOS (Liquid Crystal On Silicon) elements.

[0019] The fly-eye lenses 3a and 3b uniformize the illumination distribution of the illumination light irradiated onto the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B. The illumination light WiL emitted from the fly-eye lens 3b is incident on the polarization conversion element 4. The polarization conversion element 4 aligns the s-polarized light (first polarization) and p-polarized light (second polarization) contained in the illumination light WiL to one of the two polarizations. As an example, the polarization conversion element 4 transmits the s-polarized light using a polarizing beam splitter, and converts the p-polarized light reflected by the polarizing beam splitter into s-polarized light using a half-wave plate and emits it.

[0020] The illumination light WiL, which has been converted into s-polarized light and is output from the polarization conversion element 4, is collected by a collecting lens 5 and enters a cross dichroic mirror 6. The cross dichroic mirror 6 separates the s-polarized illumination light WiL into yellow illumination light YiL and blue illumination light BiL.

[0021] The yellow illumination light YiL separated by the cross dichroic mirror 6 is incident on and reflected by mirror 71, and then incident on dichroic mirror 72. The dichroic mirror 72 transmits red illumination light RiL contained in the yellow illumination light YiL and reflects green illumination light GiL contained in the yellow illumination light YiL. The red illumination light RiL is collected by a collecting lens 73 and incident on a reflective polarizing plate 74. Here, the reflective polarizing plate 74 transmits s-polarized light and reflects p-polarized light. The reflective polarizing plate 74 and reflective polarizing plates 84 and 94 described below can be configured with a wire grid.

[0022] The R light modulation element 10R generates and reflects red modulated light Rm by modulating the s-polarized red illumination light RiL incident via the reflective polarizing plate 74 in accordance with red data (R data) in the video data. The red modulated light Rm is p-polarized, and is reflected by the reflective polarizing plate 74 to enter the color synthesis prism 21.

[0023] The green illumination light GiL reflected by the dichroic mirror 72 is collected by the collecting lens 83 and enters the reflective polarizing plate 84. Here, the reflective polarizing plate 84 transmits s-polarized light and reflects p-polarized light. The G light modulation element 10G generates and reflects green modulated light Gm by modulating the s-polarized green illumination light GiL incident via the reflective polarizing plate 84 in accordance with green data (G data) in the video data. The green modulated light Gm is p-polarized light, and is reflected by the reflective polarizing plate 84 to enter the color synthesis prism 21.

[0024] The blue illumination light BiL separated by the cross dichroic mirror 6 is incident on and reflected by a mirror 91, and then incident on a condenser lens 93. The blue illumination light BiL is condensed by the condenser lens 93 and incident on a reflective polarizing plate 94. Here, the reflective polarizing plate 94 transmits s-polarized light and reflects p-polarized light.

[0025] The B light modulation element 10B generates and reflects blue modulated light Bm by modulating the s-polarized blue illumination light BiL incident via the reflective polarizing plate 94 in accordance with blue data (B data) in the video data. The blue modulated light Bm is p-polarized, and is reflected by the reflective polarizing plate 94 to enter the color synthesis prism 21.

[0026] The color synthesis prism 21 synthesizes the red modulated light Rm, the green modulated light Gm, and the blue modulated light Bm to generate a full-color image. The projection lens 22 projects the full-color image onto a screen (not shown).

[0027] 1 uses a reflective polarizing plate 74 that transmits s-polarized light and reflects p-polarized light, but as shown in Fig. 3, a reflective polarizing plate 74' that reflects s-polarized light and transmits p-polarized light may be used instead of the reflective polarizing plate 74. Similarly, reflective polarizing plates 84 and 94 may use a reflective polarizing plate that reflects s-polarized light and transmits p-polarized light instead of the reflective polarizing plates 84 and 94 that transmit s-polarized light and reflect p-polarized light.

[0028] The projection display device 100 described above is one configuration example of a projection display device, and the configuration of the light source unit 1 is not limited to the configuration shown in Fig. 2, and the configuration of the illumination optical system is not limited to the configuration shown in Fig. 1. The light source unit 1 may be configured to include a white lamp such as a mercury lamp as a light source. The projection display device 100 may be configured to include an R light modulation element 10R, a G light modulation element 10G, and a B light modulation element 10B, which are reflective liquid crystal display elements, and to generate a projection image by modulating red illumination light RiL, green illumination light GiL, and blue illumination light BiL according to video data (R, G, B data).

[0029] In the projection display device 100, of the s-polarized light incident on the light modulation element 10, the s-polarized light reflected by the light modulation element 10 without being modulated passes through the reflective polarizing plates 74, 84, 94 and returns toward the light source unit 1 side of the reflective polarizing plates 74, 84, 94. The s-polarized light reflected by the light modulation element 10 without being modulated may return to the illumination optical system, be reflected by optical elements such as the condenser lenses 73, 83, 93 in the illumination optical system, and re-enter the light modulation element 10. The s-polarized light reflected by the light modulation element 10 without being modulated may return to the light source unit 1, be reflected, and re-enter the light modulation element 10.

[0030] If the image to be displayed on the screen is black and the pixel values ​​of the R, G, and B data are 0, the s-polarized light incident on the light modulation element 10 is not modulated by the light modulation element 10, and most of the s-polarized light returns to the light source unit 1. If the image to be displayed on the screen is gray, some of the s-polarized light incident on the light modulation element 10 is modulated by the light modulation element 10 and heads toward the projection lens 22, and the remaining part returns to the light source unit 1 without being modulated by the light modulation element 10. If the image to be displayed on the screen is white and the pixel values ​​of the R, G, and B data are maximum values, most of the s-polarized light incident on the light modulation element 10 is modulated by the light modulation element 10 and heads toward the projection lens 22.

[0031] In this way, the extent to which the s-polarized light that enters the light modulation element 10 passes through the reflective polarizing plates 74, 84, 94 and returns to the light source unit 1 side of the reflective polarizing plates 74, 84, 94 varies depending on the image to be displayed on the screen. Also, the intensity of the re-incident illumination light that is reflected by an optical element located on the light source unit 1 side of the reflective polarizing plates 74, 84, 94 or the light source unit 1 and re-enters the light modulation element 10 via the reflective polarizing plates 74, 84, 94 varies depending on the image to be displayed on the screen.

[0032] The projection display device 100 includes an element / light source driver 30 shown in Fig. 4, which is not shown in Fig. 1. As shown in Fig. 4, the element / light source driver 30 includes an image analyzer 31, a reference re-incident illumination light intensity memory 32, a light source controller 33, a light source driver 34, a delay controller 35, a light source light quantity change delay amount holder 36, a delayer 37, a red driver (R driver) 38R, a green driver (G driver) 38G, and a blue driver (B driver) 38B. The image analyzer 31 includes a re-incident illumination light intensity calculator 311 and an image delay amount calculator 312.

[0033] 4, R data Dr, G data Dg, and B data Db constituting the video data are input to the video analysis unit 31. The re-incident illumination light intensity calculation unit 311 calculates the intensity of re-incident illumination light that is reflected without being modulated by the light modulation element 10, returns to the light source unit 1 side, and is reflected by an optical element in the illumination optical system or the light source unit 1 and re-enters the light modulation element 10, by analyzing the video of the target frame. The target frame for which the video is analyzed may be each frame constituting the video data, or may be one frame out of two or more frames.

[0034] The re-incident illumination light intensity calculation unit 311 calculates the intensity of the re-incident illumination light based on the pixel values ​​of all pixels constituting a target frame in the video data, and calculates a total value by adding up the intensities of the re-incident illumination light in the target frame. The re-incident illumination light intensity calculation unit 311 obtains the luminance value of each pixel in each frame based on the pixel value of each pixel in the R data Dr, the pixel value of each pixel in the G data Dg, and the pixel value of each pixel in the B data Db, and calculates the intensity and total value of the re-incident illumination light.

[0035] The ratio between the intensity of the s-polarized light reflected without being modulated by the light modulation element 10, returning to the illumination optical system, reflected by an optical element in the illumination optical system, and re-entering the light modulation element 10, and the intensity of the light reflected back to the light source unit 1 and re-entering the light modulation element 10, can be determined in advance by an experiment. The irradiation intensity of the illumination light irradiated onto the light modulation element 10 is not uniform within the plane of the light modulation element 10, and is lower at the left and right ends in the horizontal direction and the top and bottom ends in the vertical direction, as shown in Figures 5A and 5B.

[0036] When the s-polarized light reflected without being modulated by the light modulation element 10 returns to the light source unit 1, is reflected, and re-enters the light modulation element 10, it is not affected by the characteristics of the irradiation intensity shown in Figures 5A and 5B. This is because the characteristics of the irradiation intensity are offset by the re-entry returning to the light source unit 1. When the s-polarized light reflected without being modulated by the light modulation element 10 is reflected by an optical element in the illumination optical system, and re-enters the light modulation element 10, it is affected by the characteristics of the irradiation intensity shown in Figures 5A and 5B.

[0037] Therefore, it is preferable that the re-incident illumination light intensity calculation unit 311 calculates the intensity of the s-polarized light that is reflected by an optical element in the illumination optical system and re-incident on the light modulation element 10, taking into account the irradiation intensity at each horizontal and vertical position of the s-polarized light that is incident on the light modulation element 10.

[0038] The reference re-incident illumination light intensity storage unit 32 stores a reference sum value obtained by summing up the intensities of the re-incident illumination light for all pixels when a reference frame image is displayed on the screen (light modulation element 10). The reference frame image is, for example, a projection image in which each pixel in the R data Dr, G data Dg, and B data Db constituting the frame has a uniform pixel value at each gradation from the minimum gradation to the maximum gradation throughout the entire target frame.

[0039] Light source control unit 33 compares the total value of the re-incident illumination light calculated by re-incident illumination light intensity calculation unit 311 with the reference total value of the selected reference frame image, and controls the amount of light emitted by light source 11 in light source unit 1. Specifically, light source control unit 33 determines a drive current value for controlling the amount of light emitted by blue laser element 11e in light source 11. Light source drive unit 34 drives light source 11 so as to pass a current of the drive current value determined by light source control unit 33 to each blue laser element 11e.

[0040] The light source control unit 33 may select the reference frame image as follows. As a first example, the light source control unit 33 selects a reference frame image having the same pixel value as the pixel value of the representative pixel, with the central pixel of the target frame in the video data being the representative pixel. The light source control unit 33 decreases the drive current value if the sum of the re-incident illumination light supplied from the re-incident illumination light intensity calculation unit 311 is greater than the reference sum of the reference frame image, and increases the drive current value if the sum of the re-incident illumination light is less than the reference sum of the reference frame image. In the first example, the brightness of the center of each frame of the video data can be accurately corrected.

[0041] As a second example, the light source control unit 33 divides a target frame in the video data into multiple sections, sets the center pixel of each section as a representative pixel, and selects a reference frame image having a pixel value equal to the average pixel value of the multiple representative pixels. If the total value of the re-incident illumination light supplied from the re-incident illumination light intensity calculation unit 311 is greater than the reference total value of the reference frame image, the light source control unit 33 lowers the drive current value, and if the total value of the re-incident illumination light is less than the reference total value of the reference frame image, the light source control unit 33 raises the drive current value. In the second example, the brightness can be corrected to an appropriate level throughout each frame.

[0042] The method in which the light source control unit 33 selects the reference frame image is not limited to the first or second example. The light source control unit 33 may set a region of interest of a predetermined size in the center of the target frame, and select a reference frame image having a pixel value equal to the average value of the pixel values ​​of all pixels in the region of interest. In this way, the light source control unit 33 may select one of a plurality of methods for selecting a reference frame image.

[0043] In this way, in the element / light source driving section 30, the light source control section 33 controls the amount of light emitted by the light source 11, thereby correcting the change in display luminance caused by the illumination light being re-entered into the light modulation element 10. Unlike the method of multiplying the color data (R data Dr, G data Dg, and B data Db) by a gain, this correction method does not cause the pixel value to reach its maximum value and result in blown-out highlights. Therefore, by being equipped with the element / light source driving section 30, the projection display device 100 is able to appropriately correct the change in display luminance.

[0044] Incidentally, when the frames displayed on the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B are switched, it is desirable that the timing at which the light source driving unit 34 drives the light source 11 to switch the amount of light emission and the amount of light emission actually switches coincides with the timing at which the image is actually displayed on the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B.

[0045] There is a delay time of a predetermined time between the time when the light source driving unit 34 switches the driving current value of the previous frame to the driving current value of the current frame in response to the change of the frame and the time when the driving current value flowing through the blue laser element 11e actually changes and the amount of light emission changes. This delay time is a fixed time. In the light modulation element 10, the response characteristics when the applied voltage changes are different depending on the characteristics of the liquid crystal. There are cases where a response time of about several ms is required until the frame displayed on the light modulation element 10 is switched and the brightness of the image displayed on the screen changes. Furthermore, the response time changes depending on how the brightness value changes from the previous frame to the current frame. Typically, the larger the difference in brightness value between the previous frame and the current frame, the longer the response time.

[0046] The delay time caused by the response time of the light modulation element 10 from the time when the frame of the video data is switched from the previous frame to the current frame until the video of the current frame is displayed on the light modulation element 10 is defined as a first delay time DL10 shown in Fig. 6A. As shown in Fig. 6A, the first delay time DL10 varies in the range from a minimum delay time DLmin to a maximum delay time DLmax. The video delay amount calculation unit 312 calculates the first delay time DL10 by comparing the previous frame with the current frame.

[0047] A fixed delay time from when the frame displayed on the light modulation element 10 is switched from the previous frame to the current frame until the light source 11 emits light with an amount of light corresponding to the current frame is set as a second delay time DL11 shown in Fig. 6A. The first delay time DL10 and the second delay time DL11 are usually not the same.

[0048] The light source light quantity change delay amount storage unit 36 ​​stores a second delay time DL11 measured in advance. The light source light quantity change delay amount storage unit 36 ​​can be configured, for example, with a non-volatile memory. The delay control unit 35 compares the first delay time DL10 calculated by the video delay amount calculation unit 312 with the second delay time DL11 stored in the light source light quantity change delay amount storage unit 36 ​​every time a frame is switched. The R data Dr, G data Dg, and B data Db are supplied to an R driving unit 38R, a G driving unit 38G, and a B driving unit 38B, respectively, via a delay unit 37.

[0049] As shown in FIG. 6B, if the first delay time DL10 is longer than the second delay time DL11, the delay control unit 35 sets the delay amount in the delay unit 37 to 0, and delays the timing at which the light source control unit 33 controls the light source drive unit 34, which drives the light source 11 to emit light with an amount of light emission corresponding to the current frame, by a time DL11a. The delay control unit 35 delays the timing at which the light source drive unit 34 is controlled so that the timing at which the image of the current frame is displayed on the light modulation element 10 and the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame are brought closer together. As shown in FIG. 6B, it is preferable that the delay control unit 35 delays the timing at which the light source drive unit 34 is controlled so that the timing at which the image of the current frame is displayed on the light modulation element 10 and the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame coincide with each other.

[0050] As shown in FIG. 6C, if the second delay time DL11 is longer than the first delay time DL10, the delay control unit 35 controls the delay amount in the delay unit 37 to be a time DL10a exceeding 0, and delays the R data Dr, the G data Dg, and the B data Db by the delay unit 37. The delay control unit 35 controls the delay amount by the delay unit 37 so as to bring the timing at which the image of the current frame is displayed on the light modulation element 10 closer to the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame. As shown in FIG. 6C, it is preferable that the delay control unit 35 controls the delay amount by the delay unit 37 so as to match the timing at which the image of the current frame is displayed on the light modulation element 10 with the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame.

[0051] In this way, the delay control unit 35 preferably controls the delay amount by the delay unit 37 and controls the timing of controlling the light source drive unit 34 by the light source control unit 33 so that the timing when the image of the current frame is displayed on the light modulation element 10 coincides with the timing when the light source 11 emits the light amount corresponding to the current frame. Then, as shown in Fig. 6D, the projected image is displayed on the screen with a delay time that varies between the minimum delay time DLsmin corresponding to the second delay time DL11 and the maximum delay time DLsmax corresponding to the maximum delay time DLmax of the first delay time DL10. According to the control method of the light source control unit 33 and the delay unit 37 by the delay control unit 35 shown in Fig. 6D, the frame length of the projected image displayed on the screen varies slightly.

[0052] The operation of the projection display device 100, which is a control method for the projection display device executed by the projection display device 100 (element / light source driving unit 30), will be further described using the flowcharts shown in Figures 7A and 7B. In Figures 7A and 7B, each frame is treated as a target frame. In Figure 7A, when video data is input to the projection display device 100 and processing is started, the video analysis unit 31 determines in step S11 whether or not the frame of the video data has been switched. If the frame of the video data has not been switched (NO), the video analysis unit 31 repeats the processing of step S11.

[0053] If the frame of the video data has been switched in step S11 (YES), the re-incident illumination light intensity calculation unit 311 calculates a sum value by summing the intensities of the re-incident illumination light based on the pixel values ​​of all pixels of the current frame in step S21. The light source control unit 33 selects a reference sum value of the reference frame image corresponding to the current frame in step S22. The light source control unit 33 compares the sum value calculated in step S21 with the reference sum value selected in step S22 to determine the amount of light emitted by the light source 11 in step S23.

[0054] In step S31, the image delay amount calculation unit 312 calculates a first delay time DL10 until the image of the current frame is displayed on the light modulation element 10. In step S32, the delay control unit 35 compares the first delay time DL10 with a second delay time DL11 until the light source 11 emits light of an amount corresponding to the current frame. In FIG. 7B, in step S33, the delay control unit 35 determines whether the first delay time DL10 is longer than the second delay time DL11. If the first delay time DL10 is longer than the second delay time DL11 (YES), in step S34, the delay control unit 35 determines a delay amount for delaying the timing of emitting light of an amount corresponding to the current frame, and shifts the process to step S12.

[0055] If the first delay time DL10 is not longer than the second delay time DL11 in step S33 (NO), the delay control unit 35 determines whether the second delay time DL11 is longer than the first delay time DL10 in step S35. If the second delay time DL11 is longer than the first delay time DL10 (YES), the delay control unit 35 determines the amount of delay by which the video data is delayed in step S36, and shifts the process to step S12. If the second delay time DL11 is not longer than the first delay time DL10 (NO), the delay control unit 35 shifts the process to step S12.

[0056] In step S12, the element / light source driving unit 30 drives the light source unit 1 and the light modulation element 10 to project an image onto the screen based on the determined amount of light emission and delay, and transitions to step S13. In step S13, the element / light source driving unit 30 determines whether or not to end the operation of projecting the image onto the screen. If the operation of projecting the image onto the screen is not to be ended (NO), the element / light source driving unit 30 repeats the processing from step S11 onwards shown in FIG. 7A. If the operation of projecting the image onto the screen is to be ended (YES), the element / light source driving unit 30 ends the processing.

[0057] In Figures 7A and 7B, the processes of steps S21 to S23 are followed by the processes of steps S31 to S36, but the order may be reversed, and the processes of steps S21 to S23 and the processes of steps S31 to S36 may be executed in parallel.

[0058] 6B and 6C, the delay control unit 35 controls one of the delay amount by the delay unit 37 and the timing at which the light source control unit 33 controls the light source drive unit 34 based on the result of comparing the first delay time DL10 and the second delay time DL11. This causes the timing at which the image of the current frame is displayed on the light modulation element 10 to coincide with the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame. It is also possible to control both the delay amount by the delay unit 37 and the timing at which the light source control unit 33 controls the light source drive unit 34 to cause the timing at which the image of the current frame is displayed on the light modulation element 10 to coincide with the timing at which the light source 11 emits light with an amount of light emission corresponding to the current frame.

[0059] The delay control unit 35 controls at least one of the amount of delay caused by the delay device 37 and the timing at which the light source control unit 33 controls the light source driving unit 34, so as to match the timing at which the image of the current frame is displayed on the light modulation element 10 with the timing at which the light source 11 emits the amount of light corresponding to the current frame.

[0060] Furthermore, a preferred configuration example of the element / light source driver 30 will be described. It is preferable that the delay controller 35 controls the amount of delay by the delay device 37 and the timing at which the light source controller 33 controls the light source driver 34 as follows. Fig. 8A shows a case where the first delay time DL10 is the minimum delay time DLmin. The delay controller 35 controls the delay device 37 to delay the video data by a time DL10a that is the difference between the maximum delay time DLmax and the minimum delay time DLmin, which is the first delay time DL10 at that time. The delay time DL10a at this time is the maximum delay time.

[0061] Fig. 8B shows a case where the first delay time DL10 is an intermediate delay time between the minimum delay time DLmin and the maximum delay time DLmax. The delay control unit 35 controls the delay unit 37 to delay the video data by a time DL10a that is the difference between the maximum delay time DLmax and the intermediate delay time that is the first delay time DL10 at that time. The delay time DL10a at this time is shorter than the maximum delay time DL10a in Fig. 8A.

[0062] 8C shows a case where the first delay time DL10 is the maximum delay time DLmax. The difference time DL10a between the maximum delay time DLmax and the first delay time DL10 at that time, which is the maximum delay time DLmax, is 0. Therefore, the delay control unit 35 sets the amount of delay by the delay unit 37 to 0.

[0063] In this way, the delay control unit 35 delays the video data by the difference between the maximum delay time DLmax and the first delay time DL10 for each frame using the delay unit 37. There are cases where the delay amount of the video data is zero.

[0064] As shown in Fig. 8D, the delay control unit 35 controls the light source control unit 33 to delay the timing of controlling the light source drive unit 34, which drives the light source 11 to emit the amount of light corresponding to the current frame, by a time DL11a that is the difference between the maximum delay time DLmax and the second delay time DL11. Then, as shown in Fig. 8D, regardless of the delay time DL10 between the minimum delay time DLmin and the maximum delay time DLmax, the projected image is displayed on the screen with a delay of a fixed delay time DLfix that corresponds to the maximum delay time DLmax.

[0065] 8A to 8D, the control method of the light source control unit 33 and the delay unit 37 by the delay control unit 35 in the preferred configuration example of the element / light source driving unit 30 can keep the frame length of the projection image displayed on the screen constant. Therefore, according to the preferred configuration example of the element / light source driving unit 30, the quality of the projection image displayed on the screen can be improved.

[0066] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0067] 10R Red light modulation element (R light modulation element, red reflective LCD display element) 10G Green light modulation element (G light modulation element, green reflective LCD element) 10B Blue light modulation element (B light modulation element, blue reflective liquid crystal display element) 31 Video Analysis Department 32 Reference re-incident illumination light intensity storage unit 33 Light source control unit 34 Light source driver 35 Delay control section 36 Light source light quantity change delay amount storage unit 37 Delay Unit 38R Red drive unit (R drive unit) 38G Green drive unit (G drive unit) 38B Blue drive unit (B drive unit) 311 Re-incident illumination light intensity calculation unit 312 Video Delay Calculation Unit

Claims

1. a re-incident illumination light intensity calculation unit that calculates, for each pixel constituting a target frame for analyzing an image among each frame of image data to be displayed on a reflective liquid crystal display element, an intensity of re-incident illumination light which is the first polarized light, of a first polarized light in illumination light including first and second polarized light that is incident on the reflective liquid crystal display element via a polarizing plate, is reflected without being modulated by the reflective liquid crystal display element, returns toward the light source unit side relative to the polarizing plate, and is reflected by an optical element located toward the light source unit side relative to the polarizing plate or by the light source unit, and re-incidents on the reflective liquid crystal display element via the polarizing plate, and calculates a sum value obtained by adding up the intensities of the re-incident illumination light calculated for all pixels constituting the target frame; a reference re-incident illumination light intensity storage unit that stores a reference sum value obtained by summing up the intensities of the re-incident illumination light for each pixel when a reference frame image from a minimum grayscale to a maximum grayscale is displayed on the reflective liquid crystal display element; a light source control unit that selects a reference sum value of any of the reference frame images based on the target frame, and compares the sum value calculated by the re-incident illumination light intensity calculation unit with the selected reference sum value to control an amount of light emitted by a light source included in the light source unit; A projection display device comprising:

2. a video delay amount calculation unit that calculates a first delay time from a point in time when a frame to be displayed on the reflective liquid crystal display element in the video data is switched from an immediately preceding frame to a current frame until the video of the current frame is displayed on the reflective liquid crystal display element; a delay device for delaying the image data to be supplied to the reflective liquid crystal display element; a delay control unit that controls at least one of a delay amount by which the video data is delayed by the delay device so as to match a timing at which the video of the current frame is displayed on the reflective liquid crystal display element with a timing at which the light source emits light of an amount of light emission corresponding to the current frame, and a timing at which the light source control unit controls a light source drive unit that drives the light source to emit light of an amount of light emission corresponding to the current frame, based on a comparison result between the first delay time and a second delay time from a point in time when a frame in the video data to be displayed on the reflective liquid crystal display element is switched from an immediately preceding frame to a current frame until the light source emits light of an amount of light emission corresponding to the current frame; The projection display device according to claim 1 , further comprising:

3. a video delay amount calculation unit that calculates a first delay time that varies in a range from a minimum delay time to a maximum delay time from a point in time when a frame in the video data to be displayed on the reflective liquid crystal display element is switched from an immediately preceding frame to a current frame until the video of the current frame is displayed on the reflective liquid crystal display element; a delay device for delaying the image data to be supplied to the reflective liquid crystal display element; a delay control unit that controls the delay device to delay the video data by a time difference between the maximum delay time and the first delay time, and controls the light source control unit to delay a timing of controlling a light source drive unit that drives the light source to emit a light emission amount corresponding to the current frame by a time difference between the maximum delay time and a second delay time from a time point when a frame of the video data to be displayed on the reflective liquid crystal display element is switched from the previous frame to the current frame until the light source emits a light emission amount corresponding to the current frame; The projection display device according to claim 1 , further comprising:

4. For each pixel constituting a target frame for image analysis among each frame of image data to be displayed on a reflective liquid crystal display element, calculate the intensity of re-incident illumination light, which is the first polarized light of a first polarized light that is incident on the reflective liquid crystal display element via a polarizing plate in illumination light including first and second polarized light, is reflected without being modulated by the reflective liquid crystal display element, returns to the light source unit side of the polarizing plate, and is reflected by an optical element located on the light source unit side of the polarizing plate or by the light source unit and re-incident on the reflective liquid crystal display element via the polarizing plate, and calculate a combined value by adding up the intensities of the re-incident illumination light calculated for all pixels constituting the target frame; selecting a reference sum value of any one of the reference frame images based on the target frame from among reference sum values ​​obtained by summing up the intensities of the re-incident illumination light for each pixel when a reference frame image from a minimum grayscale to a maximum grayscale is displayed on the reflective liquid crystal display element, the reference sum value being stored in a reference re-incident illumination light intensity storage unit; The calculated sum value is compared with the selected reference sum value to control the amount of light emitted by the light source included in the light source unit. A method for controlling a projection display device.

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