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

Abstract

A reentered illumination light intensity calculation unit (311) calculates the intensity of reentered illumination light that is first polarization light: which is, in illumination light including first and second polarization light, light incident on a reflective liquid crystal display element; and for which a portion thereof is reflected without being modulated by a reflective liquid crystal display element, returns to a light source unit (1) side, reflects, and reenters the reflective liquid crystal display element. The reentered illumination light intensity calculation unit also calculates a total value by adding together the reentered illumination light intensities of all the pixels constituting a frame. A reference reentered 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 the amount of light which is emitted by a light source (11) provided in the light source unit (1).

Description

Projection display device and control method for projection display device

[0001] The present disclosure relates to a projection display device and a control method for a projection display device.

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

[0003] The illumination light returning to the illumination optical system or light source at a pixel, reflecting therein and then re-entering the reflective LCD element does not enter the same pixel but instead irradiates the entire reflective LCD element, and therefore when the illumination light re-enters the reflective LCD element, the display brightness of each pixel in each frame changes depending on the pixel value of the entire frame.

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

[0005] JP 2015-118224 A

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

[0007] One or more embodiments aim 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.

[0008] In a first aspect of one or more embodiments, for each pixel constituting a frame to be analyzed for video among frames 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 among illumination light including first and second polarized light that is incident on the reflective liquid crystal display element via a polarizing plate, is calculated, and the intensity of re-incident illumination light is the first polarized light that is reflected without being modulated by the reflective liquid crystal display element and 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 is re-incident on the reflective liquid crystal display element via the polarizing plate; Provided is a projection display device comprising: a re-incident illumination light intensity calculation unit that calculates a total value obtained by adding up the intensities of the re-incident illumination light calculated for each pixel; a reference re-incident illumination light intensity storage unit that stores a reference total value obtained by adding up the intensities of the re-incident illumination light for each pixel when a reference frame image from the minimum to maximum gradation is displayed on the reflective liquid crystal display element; and a light source control unit that selects a reference total value for one of the reference frame images based on the target frame, compares the total value calculated by the re-incident illumination light intensity calculation unit with the selected reference total value, and controls the amount of light emitted by a light source provided in the light source unit.

[0009] In a second aspect of one or more embodiments, for each pixel constituting a frame for which an image is to be analyzed among frames 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 among illumination light including first and second polarized light that is incident on the reflective liquid crystal display element via a polarizing plate, is calculated, the first polarized light being reflected without being modulated by the reflective liquid crystal display element, returning to the light source unit side relative to the polarizing plate, and being reflected by an optical element located on the light source unit side relative to the polarizing plate or the light source unit, and being re-incident on the reflective liquid crystal display element via the polarizing plate; a reference sum value of one of the reference frame images based on the target frame from among the reference sum values ​​obtained by summing the intensities of the re-incident illumination light for all pixels constituting the frame, which are stored in a reference re-incident illumination light intensity storage unit and are obtained by summing the intensities of the re-incident illumination light for all pixels when a reference frame image from the minimum to maximum gradation is displayed on the reflective liquid crystal display element; and a control method for a projection display device comprising the steps of: calculating a sum value by adding up the intensities of the re-incident illumination light calculated for all pixels constituting the frame; selecting a reference sum value of one of the reference frame images based on the target frame from among the reference sum values ​​obtained by summing the intensities of the re-incident illumination light for all pixels when a reference frame image from the minimum to maximum gradation is displayed on the reflective liquid crystal display element, 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.

[0010] According to one or more embodiments of the projection display device and the control method for the projection display device, it is possible to appropriately correct changes in display brightness caused by the re-entry of illumination light into a reflective liquid crystal display element.

[0011] FIG. 1 is a diagram illustrating a projection display device according to one or more embodiments. FIG. 2 is a plan view and a side view illustrating a detailed configuration of a light source unit included in the projection display device according to one or more embodiments. FIG. 3 is a diagram illustrating another type of reflective polarizer that can be used instead of the reflective polarizer shown in FIG. 1. FIG. 4 is a block diagram illustrating an example configuration of an element / light source driver included in the projection display device according to one or more embodiments. FIG. 5A is a characteristic diagram illustrating the horizontal irradiation intensity of illumination light irradiated onto a light modulation element. FIG. 5B is a characteristic diagram illustrating the vertical irradiation intensity of illumination light irradiated onto a light modulation element. FIG. 6A is a diagram illustrating a first delay time from the time when the frame is switched from the previous frame to the current frame until 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. FIG. 6B is a diagram illustrating delaying the timing of controlling the light source driver that drives the light source when the first delay time is longer than the second delay time. FIG. 6C is a diagram illustrating delaying video data when the second delay time is longer than the first delay time. FIG. 6D is a diagram illustrating a projected image on a screen being displayed with a delay that varies between a minimum delay time and a maximum delay time. FIG. 7A is a partial flowchart illustrating the operation of a projection display device according to one or more embodiments. FIG. 7B is a partial flowchart following FIG. 7A illustrating the operation of a projection display device according to one or more embodiments. FIG. 8A is a diagram illustrating the amount of delay of video data by a delay unit when the first delay time is the minimum delay time in a preferred configuration of an element / light source driver. FIG. 8B is a diagram illustrating the amount of delay of video data by a delay unit when the first delay time is intermediate between the minimum delay time and the maximum delay time in a preferred configuration of an element / light source driver. FIG. 8C is a diagram illustrating the amount of delay of video data by a delay unit when the first delay time is the maximum delay time in a preferred configuration of an element / light source driver. FIG. 8D is a diagram illustrating a projected image on a screen being displayed with a fixed delay time in a preferred configuration of an element / light source driver.

[0012] A projection display device and a control method for a projection display device according to one or more embodiments will be described below with reference to the accompanying drawings. In Fig. 1, a projection display device 100 according to one or more embodiments 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] 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 a condenser lens 12 and enters a 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 a condenser lens 18, and reflected by a mirror 17.

[0014] The blue light (B2) reflected by the mirror 17 is reflected by the dichroic mirror 16. The 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, condensed by condenser lenses 110 and 111, and directed toward phosphor wheel 120. Phosphor wheel 120 is configured to rotate a mirror-like disk 121 around a rotation axis 123 using a motor 124. Phosphor 122 is applied near the outer circumferential edge of disk 121. The blue light condensed by condenser 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 the phosphor 122 is incident on the dichroic mirror 16 via the condenser lenses 111 and 110. The dichroic mirror 16 transmits the yellow light. The blue light (B2) reflected by the dichroic mirror 16 as described above and the yellow light transmitted through the dichroic mirror 16 are emitted from the 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 a mirror 2 and enters fly-eye lenses 3a and 3b. The optical elements from the mirror 2 to just before red (R), green (G), and blue (B) light modulation elements 10R, 10G, and 10B, which will be described later, constitute an 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 will sometimes be collectively referred to as the light modulation elements 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 red, green, and blue reflective liquid crystal display elements, 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 referred to as LCOS (Liquid Crystal On Silicon) elements.

[0019] The fly-eye lenses 3a and 3b homogenize 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 into one of two polarizations. As an example, the polarization conversion element 4 transmits the s-polarized light using a polarization beam splitter, converts the p-polarized light reflected by the polarization beam splitter into s-polarized light using a half-wave plate, and emits the s-polarized light.

[0020] The s-polarized illumination light WiL emitted from the polarization conversion element 4 is condensed by the condenser lens 5 and enters the 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 a mirror 71, and then incident on a dichroic mirror 72. The dichroic mirror 72 transmits the red illumination light RiL contained in the yellow illumination light YiL and reflects the 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 polarizer 74. Here, the reflective polarizer 74 transmits s-polarized light and reflects p-polarized light. The reflective polarizer 74 and reflective polarizers 84 and 94, which will be described later, can be configured with a wire grid.

[0022] The R light modulation element 10R generates and reflects red modulated light Rm obtained by modulating the s-polarized red illumination light RiL incident thereon via the reflective polarizing plate 74 in accordance with the 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 and enters 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, which is obtained 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, and is reflected by the reflective polarizing plate 84 and enters 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 obtained by modulating the s-polarized blue illumination light BiL incident thereon 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 and enters 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, the reflective polarizing plates 84 and 94 may use reflective polarizing plates that reflect s-polarized light and transmit 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 example of the configuration 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 modulate red illumination light RiL, green illumination light GiL, and blue illumination light BiL in accordance with video data (R, G, B data) to generate a projection image.

[0029] In the projection display device 100, of the s-polarized light incident on the light modulation element 10, the s-polarized light that is reflected without being modulated by the light modulation element 10 passes through the reflective polarizers 74, 84, and 94 and returns toward the light source unit 1 from the reflective polarizers 74, 84, and 94. The s-polarized light that is reflected without being modulated by the light modulation element 10 may return to the illumination optical system, be reflected by optical elements such as condenser lenses 73, 83, and 93 in the illumination optical system, and re-enter the light modulation element 10. The s-polarized light that is reflected without being modulated by the light modulation element 10 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 at their 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, how much of the s-polarized light incident on the light modulation element 10 passes through the reflective polarizers 74, 84, 94 and returns to the light source unit 1 side of the reflective polarizers 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 closer to the light source unit 1 than the reflective polarizers 74, 84, 94 or the light source unit 1 and re-enters the light modulation element 10 via the reflective polarizers 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 analyzes the video of a target frame to calculate the intensity of re-incident illumination light that, of the s-polarized light incident on the light modulation element 10, is reflected without being modulated by the light modulation element 10, returns to the light source unit 1, 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. The target frame for video analysis may be each frame constituting the video data, or 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 finds the luminance value of each pixel in each frame based on the pixel values ​​of each pixel in the R data Dr, the pixel values ​​of each pixel in the G data Dg, and the pixel values ​​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 that is reflected without being modulated by the light modulation element 10, returns to the illumination optical system, is reflected by an optical element in the illumination optical system, and re-enters the light modulation element 10, and the intensity of the light that is returned to the light source unit 1, is reflected, and re-enters the light modulation element 10, can be determined in advance by experiment. The irradiation intensity of the illumination light that is 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 irradiation intensity characteristics shown in Figures 5A and 5B. This is because the irradiation intensity characteristics 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 irradiation intensity characteristics 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 each pixel 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 that make up 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 elements 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 a reference frame image as follows. As a first example, the light source control unit 33 sets the central pixel of a target frame in the video data as a representative pixel, and selects a reference frame image having the same pixel value as the pixel value of the representative pixel. The light source control unit 33 decreases the drive current value 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, and increases the drive current value if the total value of the re-incident illumination light is smaller than the reference total value 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, designates the central 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. The light source control unit 33 reduces the drive current value 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, and increases the drive current value if the total value of the re-incident illumination light is less than the reference total value of the reference frame image. In the second example, the brightness can be corrected to an appropriate level throughout each frame.

[0042] The method by which the light source control unit 33 selects a 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 that is the same as the average pixel value of all pixels within 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, the element / light source driver 30 corrects changes in display luminance caused by the re-entry of illumination light into the light modulation element 10 by controlling the light emission amount of the light source 11 using the light source controller 33. 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 maximize pixel values ​​and cause overexposure. Therefore, by including the element / light source driver 30, the projection display device 100 can appropriately correct changes in display luminance.

[0044] Incidentally, when the frame displayed on the R light modulation element 10R, the G light modulation element 10G, and the B light modulation element 10B is switched, it is desirable that the timing at which the light source driving unit 34 drives the light source 11 to switch the light emission amount and the light emission amount 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 predetermined delay time between the time when the light source driver 34 switches the drive current value from the previous frame to the drive current value for the current frame in response to a frame change and the time when the drive current value flowing through the blue laser element 11e actually changes and the light emission amount changes. This delay time is a fixed time. The response characteristics of the light modulation element 10 when the applied voltage changes vary depending on the characteristics of the liquid crystal. When the frame displayed on the light modulation element 10 is switched, it may take several milliseconds for the brightness of the image displayed on the screen to change. Furthermore, the response time varies depending on how the brightness value changes from the previous frame to the current frame. Typically, the greater the difference in brightness 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 designated as a first delay time DL10 shown in Fig. 6A. As shown in Fig. 6A, the first delay time DL10 varies within a 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] The fixed delay time from the time 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 of an amount corresponding to the current frame is designated as the 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 intensity change delay amount storage unit 36 ​​stores a second delay time DL11 that has been measured in advance. The light source light intensity change delay amount storage unit 36 ​​can be configured, for example, with a nonvolatile 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 intensity 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 via a delay unit 37 to an R driver 38R, a G driver 38G, and a B driver 38B, respectively.

[0049] 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 by a time DL11a 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 corresponding to the current frame. The delay control unit 35 delays the timing at which the light source drive unit 34 is controlled so as to bring closer 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 corresponding to the current frame. 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 as to coincide 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 corresponding to the current frame.

[0050] 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 a time DL10a that exceeds zero, thereby delaying the R data Dr, G data Dg, and B data Db using the delay unit 37. The delay control unit 35 controls the delay amount in the delay unit 37 so as to bring closer the timing when the image of the current frame is displayed on the light modulation element 10 and the timing when 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 in the delay unit 37 so as to coincide the timing when the image of the current frame is displayed on the light modulation element 10 with the timing when 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 amount of light corresponding to the current frame. Then, as shown in Fig. 6D, the projected image is displayed on the screen with a delay 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 and light source drive 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 begins, the video analysis unit 31 determines in step S11 whether the frame of the video data has changed. If the frame of the video data has not changed (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 total value by adding up the intensities of the re-incident illumination light based on the pixel values ​​of all pixels in the current frame in step S21. The light source control unit 33 selects a reference total value of the reference frame image corresponding to the current frame in step S22. The light source control unit 33 compares the total value calculated in step S21 with the reference total value selected in step S22 to determine the light emission amount of the light source 11 in step S23.

[0054] In step S31, the video delay amount calculation unit 312 calculates a first delay time DL10 required for the video of the current frame to be 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 required for the light source 11 to emit 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 by which to delay the timing of emitting light of an amount corresponding to the current frame, and proceeds 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 in step S35 whether the second delay time DL11 is longer than the first delay time DL10. If the second delay time DL11 is longer than the first delay time DL10 (YES), the delay control unit 35 determines the delay amount by which to delay the video data in step S36 and proceeds to step S12. If the second delay time DL11 is not longer than the first delay time DL10 (NO), the delay control unit 35 proceeds 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 light emission amount and delay amount, and then proceeds 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 has not been ended (NO), the element / light source driving unit 30 repeats the processing from step S11 onwards shown in Figure 7A. If the operation of projecting the image onto the screen has been ended (YES), the element / light source driving unit 30 ends the processing.

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

[0058] 6B and 6C , the delay control unit 35 controls either the amount of delay by the delay unit 37 or 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 amount of delay by the delay unit 37 and the timing at which the light source control unit 33 controls the light source drive unit 34, thereby causing 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 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] Next, a preferred configuration example of the element / light source driver 30 will be described. The delay controller 35 preferably 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 in this case is the maximum delay time.

[0061] 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, which is the first delay time DL10 at that time. The delay time DL10a in this case 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 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. The delay amount of the video data may be zero.

[0064] 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 the difference DL11a 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 the fixed delay time DLfix corresponding 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 makes it possible to keep the frame length of the projected image displayed on the screen constant. Therefore, according to the preferred configuration example of the element / light source driving unit 30, it is possible to improve the quality of the projected image displayed on the screen.

[0066] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

[0067] This application claims priority based on Japanese Patent Application No. 2023-158432, filed with the Japan Patent Office on September 22, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. A re-incident illumination light intensity calculation unit calculates, 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, the intensity of re-incident illumination light, which is the first polarized light among the first polarized light incident on the reflective liquid crystal display element via a polarizing plate in illumination light including first and second polarized light, which is reflected without being modulated by the reflective liquid crystal display element, returns toward 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 calculates a total value obtained by adding up the intensities of the re-incident illumination light calculated for all pixels constituting the target frame; and a reference re-incident illumination light intensity storage unit stores a reference total value obtained by adding up the intensities of the re-incident illumination light of each pixel when a reference frame image from the minimum grayscale to the maximum grayscale is displayed on the reflective liquid crystal display element. a light source control unit that selects a reference sum value of one 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 the amount of light emitted by a light source provided in the light source unit.

2. The projection display device according to claim 1, further comprising: an image delay amount calculation unit which calculates a first delay time from a point in time when a frame of the image data to be displayed on the reflective liquid crystal display element is switched from a previous frame to a current frame until the image of the current frame is displayed on the reflective liquid crystal display element; a delay unit which delays the image data to be supplied to the reflective liquid crystal display element; and a delay control unit which controls at least one of the delay amount by which the image data is delayed by the delay unit so as to match the timing at which the image of the current frame is displayed on the reflective liquid crystal display element and the timing at which the light source emits the 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 the frame of the image data to be displayed on the reflective liquid crystal display element is switched from a previous frame to a current frame until the light source emits the amount of light emission corresponding to the current frame.

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

4. 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, calculate the intensity of re-incident illumination light, which is the first polarized light among the first polarized light that is incident on the reflective liquid crystal display element through 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 the light source unit and re-incidents on the reflective liquid crystal display element through the polarizing plate, and calculate a total value by adding up the intensities of the re-incident illumination light calculated for all pixels constituting the target frame; select a reference total value of one of the reference frame images based on the target frame from among reference total values ​​stored in a reference re-incident illumination light intensity storage unit, which are obtained by adding up, for all pixels, the intensities of the re-incident illumination light of each pixel when reference frame images from the minimum grayscale to the maximum grayscale are displayed on the reflective liquid crystal display element; and control the amount of light emitted by the light source provided in the light source unit by comparing the calculated total value with the selected reference total value. A method for controlling a projection display device.

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