Projection type display device

Abstract

To inhibit display unevenness.SOLUTION: A display control circuit: supplies a data signal corresponding to gradation level of a video pixel corresponding to a panel pixel to the one panel pixel for each four unit periods included in one-frame period; controls for each four unit periods the position of a projection pixel to an optical path shift element to a projection position corresponding to the video pixel; and when shifting from one projection position corresponding to one video pixel of four video pixels to other projection positions corresponding to other video pixels, shifts via other points than a straight line connecting the one projection position and the other projection position. An amount of travel in at least one shift of four shifts in the one-frame period is equal to or more than one-pixel of the panel pixel.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a projection display device. [Background technology]

[0002] In a projection display device that projects image light created by a liquid crystal panel or the like onto a screen, etc., a technique for artificially increasing the resolution by using a light path shift element is known. In detail, in a projection display device, one frame period is divided into a plurality of unit periods, and the projection position of one panel pixel in the liquid crystal panel is shifted for each of the plurality of unit periods, and in each unit period, a gray scale level specified by video pixel data is individually expressed (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-139968 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above technology has an issue in that, when viewed over one frame period, relatively dark areas and relatively bright areas are unevenly distributed in the projected image, which is perceived as unevenness and reduces the display quality. [Means for solving the problem]

[0005] In order to solve the above problems, a projection type display device according to one aspect of the present disclosure includes a liquid crystal panel having a plurality of panel pixels, a light path shift element that shifts an optical path of projection light projected from the panel pixels and projects it as a projection pixel, and a display control circuit that controls the liquid crystal panel and the light path shift element, wherein a frame period is composed of k (k is an integer of 3 or more) unit periods, one panel pixel among the plurality of panel pixels individually expresses k pieces of video pixel data for each of the k unit periods, and the display control circuit controls a video image corresponding to the one panel pixel for each of the k unit periods. A data signal corresponding to the gradation level of the raw data is supplied to the one panel pixel, and the position of the projection pixel is controlled for the light path shift element to a projection position corresponding to the image pixel data for each of the k unit periods, and when shifting from one projection position corresponding to one image pixel data to another projection position corresponding to another image pixel data among the k image pixel data, the projection pixel passes through a point other than a straight line connecting the one projection position and the other projection position, and the amount of movement in at least one shift among the k shifts in the frame period is equal to or greater than one pixel of the panel pixel. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing a projection type display device according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing a configuration of a projection display device. [Diagram 3] 1 is a diagram showing the relationship between an arrangement of image pixels and an arrangement of panel pixels in a projection display device. [Figure 4] FIG. 1 is a diagram showing the relationship between one frame period and a unit period in a projection display device. [Diagram 5] FIG. 4 is a diagram showing projection positions in one frame period in the first embodiment. [Figure 6] FIG. 2 is a diagram showing video pixels expressed by one panel pixel in one frame period. [Figure 7] FIG. 1 is a perspective view showing a configuration of a liquid crystal panel in a projection display device. [Figure 8]FIG. 2 is a cross-sectional view showing the structure of a liquid crystal panel. [Figure 9] FIG. 2 is a block diagram showing an electrical configuration of a liquid crystal panel. [Figure 10] FIG. 2 is a diagram showing a configuration of a pixel circuit in a liquid crystal panel. [Figure 11] FIG. 2 is a diagram showing the relationship between video pixels, panel pixels, and projection positions in one frame period in the first embodiment. [Figure 12] FIG. 2 is an explanatory diagram of the display quality of the projection type display device according to the first embodiment. [Figure 13] FIG. 11 is a diagram showing projection positions in one frame period in the second embodiment. [Figure 14] FIG. 11 is a diagram showing the relationship between video pixels, panel pixels, and projection positions in one frame period in the second embodiment. [Figure 15] 13 is an explanatory diagram of the display quality of a projection type display device according to a second embodiment. FIG. [Figure 16] FIG. 11 is a diagram showing the relationship between two frame periods and a unit period in a comparative example. [Figure 17] 11 is a diagram showing the relationship between image pixels, panel pixels, and projection positions in a comparative example. FIG. [Figure 18] FIG. 11 is an explanatory diagram of a shift in a comparative example. [Figure 19] FIG. 11 is an explanatory diagram of display quality according to a comparative example. [Figure 20] FIG. 11 is an explanatory diagram of flicker in a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a projection display device according to an embodiment will be described with reference to the drawings. In each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples, various technically preferable limitations are attached, but the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0008] FIG. 1 is a diagram showing an optical configuration of a projection display device 1 according to a first embodiment. As shown in the figure, the projection display device 1 includes liquid crystal panels 100R, 100G, and 100B. A lamp unit 2102 consisting of a white light source such as a laser is provided inside the projection display device 1. Projection light emitted from this lamp unit 2102 is separated into three primary colors, red (R), green (G), and blue (B), by three mirrors 2106 and two dichroic mirrors 2108 arranged inside. Of these, the R light enters the liquid crystal panel 100R, the G light enters the liquid crystal panel 100G, and the B light enters the liquid crystal panel 100B. Since the optical path of B is longer than the optical paths of R and G, it is necessary to prevent loss in the optical path of B. For this reason, a relay lens system 2121 consisting of an entrance lens 2122, a relay lens 2123, and an exit lens 2124 is provided in the optical path of B.

[0009] The liquid crystal panel 100R has a plurality of pixel circuits, as described below. Each of the plurality of pixel circuits includes a liquid crystal element. The liquid crystal elements of the liquid crystal panel 100R are driven based on a data signal corresponding to R, and have a transmittance according to the voltage of the data signal. Therefore, an R transmission image is generated in the liquid crystal panel 100R by individually controlling the transmittance of the liquid crystal elements based on a data signal corresponding to R. Similarly, a G transmission image is generated in the liquid crystal panel 100G based on a data signal corresponding to G, and a B transmission image is generated in the liquid crystal panel 100B based on a data signal corresponding to B.

[0010] The transmitted images of each color generated by the liquid crystal panels 100R, 100G, and 100B are incident on the dichroic prism 2112 from three directions. In the dichroic prism 2112, the R and B light are refracted at 90 degrees, while the G light travels straight. Therefore, the dichroic prism 2112 combines the images of each color. The combined image by the dichroic prism 2112 is incident on the projection lens 2114 via the optical path shift element 230. The projection lens 2114 enlarges and projects the composite image via the light path shift element 230 onto the screen Scr.

[0011] The light path shift element 230 shifts the light path of the light exiting from the dichroic prism 2112. In detail, the light path shift element 230 shifts the composite image projected onto the screen Scr in the left-right direction and / or the up-down direction with respect to the projection surface.

[0012] The transmitted images by the liquid crystal panels 100R and 100B are projected after being reflected by the dichroic prism 2112, whereas the transmitted image by the liquid crystal panel 100G is projected in a straight line. Therefore, the transmitted images by the liquid crystal panels 100R and 100B are in a left-right inverted relationship with the transmitted image by the liquid crystal panel 100G.

[0013] 2 is a block diagram showing an electrical configuration of the projection display device 1. As shown in the figure, the projection display device 1 includes a display control circuit 20, liquid crystal panels 100R, 100G, and 100B, and a light path shift element 230.

[0014] Video data Vid-in is supplied from a higher-level device such as a host device (not shown) in synchronization with a synchronization signal Sync. The video data Vid-in specifies the gradation levels of pixels constituting one frame period of video, for example, 8 bits for each RGB.

[0015] Note that the pixels of an image specified by the video data Vid-in are referred to as video pixels, and the data specifying the gradation level of the video pixels are referred to as video pixel data, but there may be cases where no distinction is made between video pixels and video pixel data. Also, the pixels of an image before or after synthesis by the liquid crystal panels 100R, 100G, or 100B are referred to as panel pixels. The position of the panel pixels shifted by the light path shift element 230 and projected onto the screen Scr is referred to as the projection position. In the liquid crystal panels 100R, 100G, and 100B, the panel pixels are arranged in a matrix in a plan view. In the embodiment, the arrangement of the video pixels specified by the video data Vid-in is, for example, twice as large in the vertical direction and twice as large in the horizontal direction as the arrangement of the panel pixels of the liquid crystal panels 100R, 100G, or 100B.

[0016] In the embodiment, a color image projected on the screen Scr is expressed by synthesizing the transmitted images of the liquid crystal panels 100R, 100G, and 100B. Therefore, the minimum unit of a color image can be divided into a red subpixel of the liquid crystal panel 100R, a green subpixel of the liquid crystal panel 100G, and a blue subpixel of the liquid crystal panel 100B. However, when it is not necessary to specify the color of the subpixels in the liquid crystal panels 100R, 100G, and 100B, or when only brightness is an issue, it is not necessary to refer to them as subpixels. Therefore, in this description, the display units in the liquid crystal panels 100R, 100G, and 100B will also be referred to as panel pixels.

[0017] The synchronization signal Sync includes a vertical synchronization signal that instructs the start of vertical scanning of the video data Vid-in, a horizontal synchronization signal that instructs the start of horizontal scanning, and a clock signal that indicates the timing of one video pixel in the video data Vid-in.

[0018] The display control circuit 20 includes a processing circuit 21, and conversion circuits 22R, 22G, and 22B. The processing circuit 21 controls the conversion circuits 22R, 22G, and 22B, the liquid crystal panels 100R, 100G, and 100B, and the light path shift element 230 for each of four unit periods obtained by dividing one frame period based on the synchronization signal Sync. The light path shift element 230 shifts the projection position for each unit period according to the control by the processing circuit 21. Of the video data Vid-in supplied from a higher-level device, the R component is represented as video data Va_R, the G component is represented as video data Va_G, and the B component is represented as video data Va_B.

[0019] The conversion circuit 22R temporarily stores the video data Va-R supplied from the higher-level device in an internal buffer for one or more frame periods, then reads out the video data corresponding to a unit period, converts it into an analog voltage data signal Vid_R, and supplies it to the liquid crystal panel 100R. The conversion circuits 22G and 22B are different from the conversion circuit 22R only in the color components of the video data to be converted, and the rest are common to the conversion circuit 22R. That is, the conversion circuit 22G converts the video data Va-G corresponding to a unit period into an analog voltage data signal Vid_G and supplies it to the liquid crystal panel 100G, while the conversion circuit 22B converts the video data Va-B corresponding to a unit period into an analog voltage data signal Vid_B and supplies it to the liquid crystal panel 100B.

[0020] FIG. 3 is a diagram for explaining the corresponding relationship between image pixels and panel pixels in the projection display device 1. As shown in FIG. In detail, in FIG. 3, the left column is a diagram showing a portion of the arrangement of image pixels shown in the video data Vid-in, and the right column is a diagram showing an arrangement of panel pixels corresponding to the arrangement of image pixels in the left column.

[0021] In the array in the left column, in order to distinguish the video pixels in the image represented by the video data Vid-in, for convenience, the following codes are assigned to the first row: A2 to A6, the second row: B2 to B7, the third row: C1 to C7, the fourth row: D1 to D7, the fifth row: E1 to E7, the sixth row: F1 to F7, and the seventh row: G1 to G5. Similarly, in the array in the right column of FIG. 3, in order to distinguish the panel pixels, the first row is assigned with symbols a1 to a3, the second row with symbols b1 to b3, and the third row with symbols c1 to c3.

[0022] 4 is a diagram for explaining the relationship between the frame period and the unit period in the projection display device 1 according to the first embodiment. As shown in the diagram, in the first embodiment, one frame (1F) period is divided into four unit periods. For convenience of distinguishing the four unit periods in one frame period, symbols f1, f2, f3, and f4 are assigned in chronological order.

[0023] Note that one frame period is the period during which one frame of an image represented by video data Vid-in is supplied from a higher-level device, and is 16.7 milliseconds when the frequency of the vertical synchronization signal included in the synchronization signal Sync is 60 Hz. In this case, the length of each unit period is 4.17 milliseconds, which is 1 / 4 of the length of one frame period.

[0024] In the first embodiment, the projection position is shifted for each unit period f1 to f4 obtained by dividing one frame period into four. The unit period is a period for allowing a user to view an image in which the resolution of an image in one frame period specified by video data Vid-in is reduced to ¼, as a composite image produced by the liquid crystal panels 100R, 100G, and 100B. In the following description, when the liquid crystal panels 100R, 100G, and 100B are generally described without specifying the color, they will be denoted by the reference numeral 100.

[0025] FIG. 5 is a diagram showing projection positions in one frame period in the first embodiment. In the figure, the thick solid line frames indicate panel pixels of the liquid crystal panel 100, and the thin solid line frames correspond to image pixels. The right column is an enlarged view of the left column. The projection position in unit period f1 of one frame period is set as the reference position. In unit period f2 next to unit period f1, the projection position shifts from the reference position of unit period f1 by 0.5 panel pixels to the right in the figure and by 0.5 panel pixels downward. In other words, the projection position shifts diagonally downward to the right.

[0026] In unit period f3, the projection position shifts from the projection position in unit period f2 by 0.5 panel pixels to the left, passing through point P1 during this shift. Point P1 is, for example, a point 0.25 panel pixels away from the projection position in unit period f2 to the left and 0.25 panel pixels away downward. In short, the projection position does not shift along a straight line connecting the two points from unit period f2 to unit period f3, but passes through point P1 that is off the straight line. In detail, the projection position shifts from the projection position in unit period f2 to point P1, and then shifts from point P1 to the projection position in unit period f3.

[0027] In unit period f4, the projection position shifts from the projection position in unit period f3 by 0.5 panel pixels to the left and by 0.5 panel pixels to the bottom, passing through point P2 during this shift. Point P2 is, for example, a point that is 0.25 panel pixels away from the projection position in unit period f3 to the left and 0.75 panel pixels away from the projection position in unit period f3 to the bottom. In short, from unit period f2 to unit period f3, the projection position passes through point P2, which is off the straight line connecting the two points. From unit period f4 to unit period f1 of the next frame period, the projection position is shifted by 0.5 panel pixels to the right and 1.0 panel pixels upward from the projection position in unit period f4. That is, the projection position is shifted diagonally upward to the right. This shift returns the projection position to the reference position.

[0028] Next, focusing on one panel pixel, the video pixels expressed in one frame period will be described. Note that when a panel pixel "expresses" a certain video pixel, the liquid crystal element 120 of the panel pixel has a transmittance corresponding to the grayscale level (video pixel data) of the video pixel. For ease of explanation, the panel pixel b2 will be focused on.

[0029] FIG. 6 is a diagram showing image pixels expressed by the panel pixel b2 in the unit periods f1 to f4. In detail, panel pixel b2 expresses video pixels C4, D5, D4, and E3 in sequence during unit periods f1 to f4. In other words, panel pixel b2 expresses C4, D5, and D4 in sequence among the video pixels in two rows and two columns surrounded by a thick frame during unit periods f1 to f3, and expresses video pixel E3 other than the video pixels in two rows and two columns surrounded by a thick frame during unit period f4. Of the two rows and two columns of video pixels enclosed in a thick frame, video pixel C5 is represented in unit period f4 by panel pixel a3 diagonally above and to the right of panel pixel b2.

[0030] Next, the liquid crystal panels 100R, 100G, and 100B will be described. The liquid crystal panels 100R, 100G, and 100B have the same structure, but only the color, i.e., the wavelength, of the light incident thereon is different. Therefore, the liquid crystal panels 100R, 100G, and 100B will be generally described as the liquid crystal panel 100, without specifying the color.

[0031] FIG. 7 is a perspective view of the liquid crystal panel 100, and FIG. 8 is a cross-sectional view taken along line Hh in FIG. As shown in these figures, in the liquid crystal panel 100, an element substrate 100a on which a pixel electrode 118 is provided and an opposing substrate 100b on which a common electrode 108 is provided are bonded together with a sealing material 90 so that their electrode forming surfaces face each other while maintaining a certain gap, and liquid crystal 105 is filled in this gap.

[0032] The element substrate 100a and the counter substrate 100b are each made of a substrate having optical transparency, such as glass or quartz. As shown in FIG. 7, one side of the element substrate 100a protrudes from the counter substrate 100b. In this protruding region, a plurality of terminals 106 are provided along the horizontal direction in the figure. One end of an FPC (Flexible Printed Circuits) substrate (not shown) is connected to the plurality of terminals 106. The other end of the FPC substrate is connected to the display control circuit 20, and the above-mentioned various signals are supplied thereto.

[0033] On the surface of the element substrate 100a facing the counter substrate 100b, pixel electrodes 118 are formed by patterning a transparent conductive layer made of, for example, ITO (Indium Tin Oxide). Although not shown, a microlens is provided for each panel pixel on the counter substrate 100b (or the element substrate 100a) to efficiently send a large amount of light to the openings that become the panel pixels. With this configuration, the light that is repelled by the light shielding portion is sent to the openings of the microlens, improving the light utilization efficiency.

[0034] 9 is a block diagram showing the electrical configuration of the liquid crystal panel 100. In the liquid crystal panel 100, a scanning line driving circuit 130 and a data line driving circuit 140 are provided on the periphery of the display area 10.

[0035] In the display region 10 of the liquid crystal panel 100, pixel circuits 110 are arranged in a matrix. In detail, in the display region 10, a plurality of scanning lines 12 are provided extending in the horizontal direction in the figure, and a plurality of data lines 14 are provided extending in the vertical direction and electrically insulated from the scanning lines 12. Then, the pixel circuits 110 are provided in a matrix corresponding to the intersections of the plurality of scanning lines 12 and the plurality of data lines 14.

[0036] If the number of scanning lines 12 is m and the number of data lines 14 is n, the pixel circuits 110 are arranged in a matrix of m rows and n columns. Both m and n are integers of 2 or more. In order to distinguish the rows of the matrix in the scanning lines 12 and the pixel circuits 110, they may be referred to as 1, 2, 3, ..., (m-1), m rows from the top in the figure. Similarly, in order to distinguish the columns of the matrix in the data lines 14 and the pixel circuits 110, they may be referred to as 1, 2, 3, ..., (n-1), n ​​columns from the left in the figure.

[0037] The scanning line driving circuit 130 selects the scanning lines 12 one by one in the order of, for example, the 1st, 2nd, 3rd, ..., mth rows in accordance with the control by the display control circuit 20, and sets the scanning signal to the selected scanning line 12 to H level. Note that the scanning line driving circuit 130 sets the scanning signal to the scanning lines 12 other than the selected scanning line 12 to L level. The data line driving circuit 140 latches one row of data signals supplied from the corresponding color circuit among the conversion circuits 22R, 22G or 22B, and outputs the data signals to the pixel circuit 110 located on the scanning line 12 via the data line 14 during the period when the scanning signal to the scanning line 12 is at H level.

[0038] FIG. 10 is a diagram showing an equivalent circuit of four pixel circuits 110 arranged in two vertical rows and two horizontal columns corresponding to the intersections of two adjacent scanning lines 12 and two adjacent data lines 14. As shown in the figure, the pixel circuit 110 includes a transistor 116 and a liquid crystal element 120. The transistor 116 is, for example, an n-channel thin film transistor. In the pixel circuit 110, the gate node of the transistor 116 is connected to the scan line 12, while the source node is connected to the data line 14, and the drain node is connected to a pixel electrode 118 that has a square shape in a plan view.

[0039] A common electrode 108 is provided in common to all pixels so as to face the pixel electrode 118. A voltage LCcom is applied to the common electrode 108. Then, as described above, liquid crystal 105 is sandwiched between the pixel electrode 118 and the common electrode 108. Therefore, for each pixel circuit 110, a liquid crystal element 120 is formed in which the liquid crystal 105 is sandwiched between the pixel electrode 118 and the common electrode 108. In addition, a storage capacitor 109 is provided in parallel to the liquid crystal element 120. One end of the storage capacitor 109 is connected to a pixel electrode 118, and the other end is connected to a capacitance line 107. A time-constant voltage, for example, a voltage LCcom that is the same as the voltage applied to the common electrode 108, is applied to the capacitance line 107. The pixel circuits 110 are arranged in a matrix shape in the horizontal direction, which is the extension direction of the scanning lines 12, and in the vertical direction, which is the extension direction of the data lines 14, and therefore the pixel electrodes 118 included in the pixel circuits 110 are also arranged in the vertical and horizontal directions.

[0040] When the scanning signal of a scanning line 12 becomes H level, the transistor 116 of the pixel circuit 110 provided corresponding to the scanning line 12 becomes ON state. When the transistor 116 becomes ON state, the data line 14 and the pixel electrode 118 become electrically connected, so that the data signal supplied to the data line 14 reaches the pixel electrode 118 via the transistor 116 that has become ON state. When the scanning line 12 becomes L level, the transistor 116 becomes OFF state, but the voltage of the data signal that has reached the pixel electrode 118 is held by the capacitive property of the liquid crystal element 120 and the storage capacitance 109.

[0041] As is well known, in the liquid crystal element 120, the orientation of the liquid crystal molecules changes in response to the electric field generated by the pixel electrode 118 and the common electrode 108. Therefore, the liquid crystal element 120 has a transmittance that corresponds to the effective value of the applied voltage. In addition, the region that functions as a panel pixel in the liquid crystal element 120, i.e., the region that has a transmittance according to the effective value of the voltage, is the region where the pixel electrode 118 and the common electrode 108 overlap when the element substrate 100a and the counter substrate 100b are viewed in plan. Since the pixel electrode 118 is square in plan view, the shape of the pixel formed by the liquid crystal panel 100 is also square. In addition, in the first embodiment, the liquid crystal 105 is of a VA (Vertical Alignment) type, and is in a normally black mode in which the transmittance is at a minimum when the voltage applied to the liquid crystal element 120 is zero, and the transmittance increases as the applied voltage increases.

[0042] An operation of supplying a data signal to the pixel electrodes 118 of the liquid crystal elements 120 is executed in the order of the 1st, 2nd, 3rd, ..., mth rows in each unit period f1 to f4. As a result, a voltage according to the data signal is held in each of the liquid crystal elements 120 of the pixel circuits 110 arranged in m rows and n columns, each liquid crystal element 120 has a target transmittance, and a transmitted image of the corresponding color is generated by the liquid crystal elements 120 arranged in m rows and n columns. In this way, the generation of a transmission image is executed for each of RGB, and a color image obtained by combining RGB is projected onto the screen Scr. The data signals Vid_R, Vid_G, and Vid_B outputted corresponding to a certain unit period correspond to the RGB components of the video data corresponding to the unit period, so that a composite image of a color corresponding to a projection position is projected at the projection position during the unit period.

[0043] Next, how image pixels are visually recognized by a user due to panel pixels in the projection type display device 1 according to the first embodiment will be described.

[0044] Fig. 11 is a diagram showing which image pixels are represented at which projection positions by panel pixels in the projection display device 1 according to the first embodiment. In detail, Fig. 11 is a diagram showing at which projection positions nine panel pixels in the right column of Fig. 3 represent the image pixels in the left column of Fig. 3 during unit periods f1 to f4. Note that the thick frame in the right column of Fig. 11 indicates panel pixel b2, and the thick frame in the left column of Fig. 11 indicates an image pixel represented by the panel pixel b2. For convenience, the projection position in unit period f1 is taken as the reference position.

[0045] As shown in the figure, in a unit period f1 of a frame period, panel pixels a1, a2, a3, b1, b2, b3, c1, c2 and c3 represent hatched image pixels A2, A4, A6, C2, C4, C6, E2, E4 and E6, respectively. The arrow pointing diagonally upward to the right of the panel pixels in unit period f1 indicates the shift direction from unit period f4 of the previous frame period.

[0046] When the unit period f1 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position by 0.5 panel pixels to the right and 0.5 pixels downward in the figure from the projection position in the unit period f1, i.e., the reference position shown by the dashed line. In unit period f2, panel pixels a1, a2, a3, b1, b2, b3, c1, c2 and c3 represent, in order, hatched image pixels B3, B5, B7, D3, D5, D7, F3, F5 and F7, respectively.

[0047] When the unit period f2 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position from the projection position of the unit period f2 shown by the dashed line by 0.5 panel pixels to the left in the figure, via point P1. In unit period f3, panel pixels a1, a2, a3, b1, b2, b3, c1, c2 and c3 represent, in order, hatched image pixels B2, B4, B6, D2, D4, D6, F2, F4 and F6, respectively.

[0048] When the unit period f3 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position from the projection position of the unit period f3 shown by the dashed line by 0.5 panel pixels to the left in the figure and by 0.5 pixels downward, via point P2. In unit period f4, panel pixels a1, a2, a3, b1, b2, b3, c1, c2 and c3 represent hatched image pixels C1, C3, C5, E1, E3, E5, G1, G3 and G5, respectively.

[0049] When the unit period f4 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position by 0.5 panel pixels to the right and 1.0 panel pixels upward in the drawing from the projection position of the unit period f4 shown by the dashed line, thereby returning the projection position to the reference position.

[0050] Before describing the display quality in the first embodiment, a description will be given of degradation in display quality that occurs in a projection display device according to a comparative example.

[0051] 16 is a diagram showing which image pixels are represented at which projection positions by panel pixels in a projection display device according to a comparative example. In the comparative example, a frame period is divided into odd-numbered frame periods and even-numbered frame periods, and further, the odd-numbered frame periods are divided into unit periods f1-1 to f1-4, and the even-numbered frame periods are divided into unit periods f2-1 to f2-4.

[0052] 17 is a diagram for explaining the correspondence between image pixels and panel pixels in a projection display device according to a comparative example. Details are omitted because they overlap with those in FIG. 3, but the panel pixels shown in the right column represent the image pixels shown in the left column.

[0053] FIG. 18 is a diagram simply illustrating the image pixels represented by panel pixel p11 and the projection position in a comparative example, focusing on panel pixel p11. In the comparative example, in an odd-numbered frame period, panel pixel p11 displays the 2nd row and 2nd column video pixels included in the thick frame in the order of B11, A11, and D11 in counterclockwise direction starting from C11 for each unit period f1-1 to f1-4. Also, in the comparative example, in an even-numbered frame period, panel pixel p11 displays the 2nd row and 2nd column video pixels included in the thick frame in the order of B21, A22, and B12 in clockwise direction starting from C11 for each unit period f2-1 to f2-4.

[0054] As described above, in the liquid crystal panel 100, a microlens is provided for each panel pixel to improve the efficiency of light use. Therefore, the brightness of the panel pixel is not uniform within the plane, and in fact, as shown in Fig. 19, the brightness is higher near the center of the panel pixel and lower from the center toward the outside. Note that the frame Ppx indicates the outer edge of the panel pixel at the reference position.

[0055] In the comparative example, in odd-numbered frame periods, the panel pixels viewed in this way are shifted counterclockwise from the reference position by 0.5 panel pixels in unit periods f1-1 to f1-4, as shown in the left column of Fig. 19. For this reason, when looking at only the odd-numbered frame periods, the display is separated into bright regions that are viewed as relatively bright regions and other dark regions, and in particular, the dark regions appear in a lattice pattern and are viewed as display unevenness. However, in the comparative example, during an even frame period, as shown in the right column of Figure 19, the panel pixels are shifted clockwise from the reference position by 0.5 panel pixels in unit periods f2-1 to f2-4 in sequence, resulting in bright and dark areas appearing in positions different from those in the odd frames. Therefore, in the comparative example, when viewed over two frame periods, bright and dark regions occur alternately in different locations, making it possible to suppress display unevenness. However, it has been pointed out that in the comparative example, flicker is easily visible. This point will be explained by focusing on panel pixel p11.

[0056] FIG. 20 is a diagram showing the image pixels represented by panel pixel p11 in chronological order. The panel pixel p11 expresses video pixels C11, B11, A11, and D11 in that order in unit periods f1-1 to f1-4 of the odd frame period, and expresses video pixels C11, D21, A22, and B12 in that order in unit periods f2-1 to f2-4 of the even frame period.

[0057] Here, for example, focusing on image pixels B11 and B12 among the image pixels represented by panel pixel p11, in the comparative example, panel pixel p11 represents image pixel B11 in the second unit period f1-2 in an odd frame period, and represents image pixel B12 in the fourth unit period f2-4 in the following even frame period. In other words, after panel pixel p11 renders video pixel B11, it renders video pixel B12 six unit periods later, and then renders video pixel B11 again two unit periods later, and so on. Therefore, in the comparative example, the time intervals during which panel pixel p11 renders video pixels B11 and B12 are not uniform. In a still image, the image pixels B11 and B12 have a high correlation between their grayscale levels. Therefore, if the time intervals at which the image pixels B11 and B12 are displayed by the panel pixel p11 are not uniform, this is likely to be visually recognized as flicker, that is, blinking.

[0058] Furthermore, in the comparative example, signal processing is performed in units of two frame periods, which leads to complication and a heavy processing load compared to a configuration in which signal processing is performed in units of one frame period.

[0059] In the comparative example, the cause of the display unevenness that occurs in one frame period is that the panel pixels are larger than the image pixels, so there are areas where there is a lot of overlap due to the shift and areas where there is little overlap. In the comparative example, the grid-like dark areas that occur in either the odd frame period or the even frame period are particularly dark at the intersection of the vertical and horizontal directions. Conversely, if the optical path of the shift is changed so that the center of the panel pixel that is perceived as bright passes through an area that is easily darkened, the display unevenness can be eliminated even in a configuration in which one frame period is one unit. As described above, the brightness of the panel pixel becomes darker from the center toward the outside due to the microlens. The area that is particularly likely to become dark among the grid-like dark areas that occur when such panel pixels are shifted clockwise or counterclockwise is the area outside the area where the center of the panel pixel rotates, which is the area Ded shown by the dashed line in FIG. 19.

[0060] In the first embodiment, for example, panel pixel b2 expresses image pixels C4, D5 and D4 among the image pixels in two rows and two columns during unit periods f1 to f3, and expresses image pixel E3 other than the image pixels in two rows and two columns during unit period f4, so that the center of the panel pixel passes through the area Ded that is prone to darkening. In other words, in the first embodiment, from unit period f4 to unit period f1 of the next frame period, the light path shift element 230 shifts the projection position by 0.5 panel pixel to the right and by 1.0 panel pixel upward, so that the center of the panel pixel passes through the area Ded that is prone to becoming dark. Therefore, in the first embodiment, as shown in FIG. 12, the relatively bright central portion of the panel pixel passes through the area Ded that is likely to become dark, so that display unevenness can be reduced.

[0061] In the first embodiment, the light path shift element 230 linearly shifts the projection position from the projection position of the unit period f1 to the projection position of the unit period f2, whereas the light path shift element 230 shifts the projection position from the projection position of the unit period f2 to the projection position of the unit period f3 via the point P1. Similarly, the light path shift element 230 linearly shifts the projection position from the projection position of the unit period f4 to the projection position of the unit period f1 of the next frame period, whereas the light path shift element 230 shifts the projection position from the projection position of the unit period f3 to the projection position of the unit period f4 via the point P2.

[0062] The reason for this configuration will now be explained. As in the embodiment, when shifting from a projection position of a certain unit period to a projection position of the next unit period, assuming a configuration in which the shift is performed in the shortest possible time, specifically, a configuration in which the shift is performed along a straight line connecting two projection positions (centers of projection pixels) each other, a difference occurs in the path length of each shift. Since the speed of the shift by the light path shift element 230 is not infinitely fast, if a difference occurs in the path length of the shift, a difference occurs in the shift time until the target projection position is reached, and thus a difference occurs in the time of the image pixel expressed at the projection position for each unit period, resulting in a deterioration in display quality.

[0063] In order to reduce the difference in shift time from one projection position to the next, it should be possible to first make the shift with the longest distance between the projection positions a linear shift, and for shifts shorter than that, to make them detour shifts that go through points that are off the linear path, and then adjust the time length. In the first embodiment, the longest distance is from the projection position of unit period f4 to the projection position of unit period f1. For this reason, in the first embodiment, first, a linear shift is performed from unit period f4 to unit period f1.

[0064] Next, as candidates for the detour shift, a shift close to the path length of the linear shift from unit period f4 to f1 is preferable. There are two shifts that are close to the path length of the linear shift from unit period f4 to f1: one is the shift from unit period f1 to f2, and the other is the shift from unit period f3 to f4, both of which have the same linear path length.

[0065] Therefore, in the first embodiment, for the sake of convenience, the shift from unit period f3 to f4 is set as a detour shift so as to match the linear shift from unit period f4 to f1.

[0066] As described above, the light path shift element 230 shifts the projection position on the projection surface in a single direction, either vertically or horizontally, or in a diagonal direction by combining vertically and horizontally. Such a light path shift element 230 is generally configured to shift the light path separately on two axes, vertically and horizontally. Therefore, the time required to shift from one projection position to the next projection position is determined by the larger component when the vector of the shift is decomposed into a component along the vertical direction and a component along the horizontal direction. For this reason, when matching the detour shift with the linear shift, it is sufficient to decompose the linear shift vector into an up-down component and a left-right component, rather than the optical path travel length, and select a point where the vector component of the detour shift matches the larger of these components.

[0067] In detail, for point P2, a point is selected that satisfies the condition that the first or second sum, as follows, corresponds to 1.0 pixel of the panel pixel, which is the larger component in a linear shift from unit period f4 to f1. Here, the first sum at point P2 is the sum of the magnitude of the component along the up-down direction of the first half vector extending from the projection position of unit period f3 to point P2 and the magnitude of the component along the up-down direction of the second half vector extending from point P2 to the projection position of unit period f4. In addition, the second sum of point P2 is the sum of the magnitude of the left-right component of the first half vector extending from the projection position of unit period f3 to point P2 and the magnitude of the left-right component of the second half vector extending from point P2 to the projection position of unit period f4.

[0068] In the first embodiment, a point where point P2 satisfies the first sum is selected, specifically, as described above, a point that is 0.25 panel pixels away to the left and 0.75 panel pixels away from the projection position of unit period f3. As a result, in the roundabout shift from unit period f3 to f4, the sum of the magnitudes of the components in the up and down direction becomes 1.0 panel pixel, which is the same as the magnitude of the component along the up and down direction in the linear shift from unit period f4 to f1, which is 1.0 panel pixel. Therefore, in the first embodiment, the time required for the projection position to shift from unit period f3 to f4 is aligned with the time required for the projection position to shift from unit period f4 to f1, so that the time is smaller than in a configuration in which the time is not aligned, thereby suppressing degradation in display quality. In the detour shift from unit period f3 to f4, the sum of the magnitudes of the left and right components is 0.5 panel pixels.

[0069] From this viewpoint alone, it is not necessary to perform a detour shift from unit period f2 to f3 in accordance with the linear shift from unit period f1 to f2. That is, the linear shift vector from unit period f1 to f2 can be decomposed into a component along the up-down direction, which is 0.5 panel pixels, and a component along the left-right direction, which is 0.5 panel pixels. Also, the linear shift vector from unit period f2 to f3 is only a component along the left-right direction, which is 0.5 panel pixels. Therefore, the shift time required for both shifts is almost the same.

[0070] However, the vector of the linear shift from unit period f1 to f2 has both vertical and horizontal components, whereas the vector of the linear shift from unit period f2 to f3 has only a horizontal component. Therefore, if the unit period f2 to f3 is a linear shift, there is a possibility that a difference in display quality will appear due to the absence of a vertical component compared to the linear shift from the immediately preceding unit period f1 to f2.

[0071] Therefore, in the first embodiment, a detour shift is also performed from unit period f2 to f3 to match the linear shift from unit period f1 to f2. In detail, in the shift from unit period f2 to f3, by passing through point P1, 0.25 panel pixels are added downward and 0.25 panel pixels are added upward, resulting in a total of 0.5 panel pixels being redundantly added in the vertical direction. As a result, the magnitude of the vertical component of the vector of the detour shift from unit period f2 to f3 is 0.5 panel pixels, which is the same as the magnitude of the vertical component of the vector of the shift from unit period f1 to f2, which is 0.5 panel pixels. Therefore, in the first embodiment, the time required for the projection position to shift from unit period f1 to f2 is matched to the time required for the projection position to shift from unit period f2 to f3, and the sizes in the vertical direction are aligned, so that the time is smaller than in a configuration in which the sizes are not aligned, and degradation in display quality can be suppressed.

[0072] In the first embodiment, the magnitude of the vertical component of the linear shift vector from unit period f4 to f1 is equal to the sum of the magnitudes of the vertical components of the roundabout shift vector from unit period f3 to f4, and the magnitude of the horizontal component of the linear shift vector from unit period f4 to f1 is equal to the sum of the magnitudes of the horizontal components of the roundabout shift vector from unit period f3 to f4.

[0073] Therefore, according to the first embodiment, it is possible to suppress degradation of display quality caused by a time difference in shifting the projection position or a difference in the shift direction. In addition, in the first embodiment, signal processing is performed with one frame period as one unit, so that the configuration can be simplified and the processing load can be reduced compared to the comparative example in which signal processing is performed with two frame periods as one unit.

[0074] In the first embodiment, the detour shift from unit period f2 to the projection position of unit period f3 via point P1 is aligned with a linear shift from the projection position of unit period f4 to the projection position of unit period f1, and the detour shift from the projection position of unit period f3 to the projection position of unit period f4 via point P2 is aligned with a linear shift from the projection position of unit period f1 to the projection position of unit period f1. In this configuration, of the four shifts, two of the shift times are aligned, and the other two shift times are also aligned, but since there are two different shift times, this difference may appear as a difference in display quality. Therefore, a second embodiment in which the shift times are uniformed for the four shifts will be described. The second embodiment differs from the first embodiment in the order of the projection positions and the optical path shifts in the unit periods f1 to f4. Therefore, in the second embodiment, these differences will be mainly described.

[0075] FIG. 13 is a diagram showing the projection positions in one frame period in the projection type display device 1 according to the second embodiment.

[0076] The projection position in unit period f1 of one frame period is taken as the reference position. From unit period f1 to unit period f2 of a certain frame period, the projection position shifts 0.5 panel pixels to the left and 1.0 panel pixel downward in the figure from the reference position of unit period f1. In unit period f3, the projection position is shifted rightward by 1.0 panel pixel and upward by 0.5 panel pixel from the projection position in unit period f2.

[0077] In unit period f4, the projection position shifts leftward by 0.5 panel pixels from the projection position in unit period f3, passing through point P3 during this shift. Point P3 is, for example, a point 0.25 panel pixels to the right and 0.25 panel pixels above the projection position in unit period f3. From unit period f4 to unit period f1 of the next frame period, the projection position shifts upward from the projection position in unit period f4 by 0.5 panel pixels, passing through point P4 during this shift. Point P4 is, for example, a point 0.25 panel pixels to the right and 0.75 panel pixels upward from the projection position in unit period f4. This shift returns the projection position to the reference position.

[0078] Next, similarly to the first embodiment, attention will be focused on panel pixel b2 and the video pixels expressed in one frame period will be described.

[0079] In the second embodiment, the panel pixel b2 expresses the video pixels C4, E3, D5, and D4 in that order in unit periods f1 to f4, although this is not shown in the figure. That is, in the second embodiment, the four video pixels expressed by the panel pixel b2 in one frame period are the same, but the order of the video pixels expressed in unit periods f1 to f4 is different from that in FIG. Panel pixel b2 expresses image pixel E3 other than the image pixel in row 2, column 2 in unit period f2. Of the image pixels in row 2, column 2 enclosed in a thick frame, image pixel C5 is expressed in unit period f2 by panel pixel a3 diagonally above and to the right of panel pixel b2.

[0080] FIG. 14 is a diagram showing which image pixels are represented by panel pixels at which projection positions in the projection display device 1 according to the second embodiment.

[0081] As shown in the figure, in a unit period f1 of a frame period, panel pixels a1, a2, a3, b1, b2, b3, c1, c2 and c3 represent hatched image pixels A2, A4, A6, C2, C4, C6, E2, E4 and E6, respectively.

[0082] When the unit period f1 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position from the reference position in the unit period f1 by 0.5 panel pixels to the left and 1.0 panel pixels downward in the figure. In the unit period f2, the panel pixels a1, a2, a3, b1, b2, b3, c1, c2, and c3 respectively represent the hatched image pixels C1, C3, C5, E1, E3, E5, G1, G3, and G5. When the unit period f2 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position from the projection position in the unit period f2 by 1.0 panel pixel to the left and 0.5 pixel upward in the drawing. In the unit period f3, the panel pixels a1, a2, a3, b1, b2, b3, c1, c2, and c3 represent the hatched image pixels B3, B5, B7, D3, D5, D7, F3, F5, and F7, respectively. When unit period f3 ends, processing circuit 21 controls light path shift element 230 to shift the projection position from the projection position in unit period f3 by 0.5 panel pixels to the left in the figure via point P3. In unit period f4, panel pixels a1, a2, a3, b1, b2, b3, c1, c2, and c3 represent hatched image pixels B2, B4, B6, D2, D4, D6, F2, F4, and F6, respectively. When the unit period f4 ends, the processing circuit 21 controls the light path shift element 230 to shift the projection position from the projection position in the unit period f4 by 0.5 panel pixels upward in the drawing via point P4. This returns the projection position to the reference position.

[0083] Also in the second embodiment, for example, panel pixel b2 represents image pixels C4, D5 and D4 out of the image pixels in two rows and two columns in unit periods f1, f3 and f4, and represents image pixel E3 other than the image pixels in two rows and two columns in unit period f2, thereby causing the center of the panel pixel to pass through a dark area. In other words, in the second embodiment, the light path shift element 230 shifts the projection position leftward by 0.5 panel pixel and downward by 1.0 panel pixel from unit period f1 to unit period f2, and shifts the projection position rightward by 1.0 panel pixel and upward by 0.5 panel pixel from unit period f2 to unit period f3, so that the center of the panel pixel passes through the dark area. Therefore, in the second embodiment, as shown in FIG. 15, the relatively bright central portion of the panel pixel passes through the dark region, so that display unevenness can be reduced.

[0084] In the first embodiment, the reason why two different shift times occur among the four shifts is because there is only one shift with the longest distance (to the center of) the projection position, and there is also only one shift with the shortest distance to the projection position. Therefore, first, in the second embodiment, the projection positions in each unit period are selected so that there are two shifts in which the distance between the projection positions is the longest, and there are also two shifts in which the distance between the projection positions is the shortest. Specifically, the two shifts that result in the longest distance between the projection positions are the shift from the projection position in unit period f1 to the projection position in unit period f2, and the shift from the projection position in unit period f2 to the projection position in unit period f3. The two shifts that result in the shortest distance between the projection positions are the shift from the projection position in unit period f3 to the projection position in unit period f4, and the shift from the projection position in unit period f4 to the projection position in unit period f1.

[0085] The two shifts whose projection positions are farthest apart are defined as linear shifts, and the two shifts whose projection positions are farthest apart are defined as roundabout shifts. Of the two linear shifts, in one shift from the projection position of unit period f1 to the projection position of unit period f2, the magnitude of the component along the up-down direction is 1.0 panel pixel, and the magnitude of the component along the left-right direction is 0.5 panel pixel. Of the two linear shifts, in the other shift from the projection position of unit period f2 to the projection position of unit period f3, the magnitude of the component along the up-down direction is 0.5 panel pixel, and the magnitude of the component along the left-right direction is 1.0 panel pixel. That is, of the two linear shifts, the larger of the magnitudes of the components along the up-down direction and the left-right direction will each be 1.0 panel pixel.

[0086] For the points P3 and P4 for detouring the shift with the shortest distance between the projection positions, points that satisfy the following conditions may be selected.

[0087] First, for point P3, a point that satisfies the condition that the first sum or the second sum becomes 1.0 pixel of the panel pixel as follows may be selected. Here, the first sum at point P3 is the sum of the magnitude of the component along the up-down direction of the first half vector extending from the projection position of unit period f3 to point P3 and the magnitude of the component along the up-down direction of the second half vector extending from point P3 to the projection position of unit period f4. In addition, the second sum of point P3 is the sum of the magnitude of the left-right component of the first half vector extending from the projection position of unit period f3 to point P3 and the magnitude of the left-right component of the second half vector extending from point P3 to the projection position of unit period f4. In the second embodiment, a point where point P3 satisfies the second sum is selected; specifically, as described above, a point that is 0.25 panel pixels to the right and 0.25 panel pixels above the projection position of unit period f3. As a result, in the detour shift from unit period f3 to f4, the sum of the magnitudes of the left and right components becomes 1.0 panel pixel. In the detour shift from unit period f3 to f4, the sum of the magnitudes of the components in the up and down directions is 0.5 panel pixels.

[0088] Next, for point P4, a point that satisfies the condition that the first sum or the second sum becomes 1.0 pixel of the panel pixel may be selected in a similar manner. Here, the first sum at point P4 is the sum of the magnitude of the component along the up-down direction of the first half vector extending from the projection position of unit period f4 to point P4 and the magnitude of the component along the up-down direction of the second half vector extending from point P4 to the projection position of unit period f1. In addition, the second sum of point P4 is the sum of the magnitude of the left-right component of the first half vector extending from the projection position of unit period f4 to point P4 and the magnitude of the left-right component of the second half vector extending from point P4 to the projection position of unit period f1. In the second embodiment, a point P4 that satisfies the first sum is selected; specifically, as described above, a point that is 0.25 panel pixels to the right and 0.75 panel pixels above the projection position of unit period f3. As a result, in the detour shift from unit period f4 to f1, the sum of the magnitudes of the components in the up and down directions becomes 1.0 pixel of the panel pixel. In the detour shift from unit period f4 to f1, the sum of the magnitudes of the left and right components is 0.5 panel pixels.

[0089] In the second embodiment, in each of the four shifts, the larger of the vertical or horizontal directions is 1.0 panel pixel. Also, in the second embodiment, in each of the four shifts, the smaller of the vertical or horizontal directions is 0.5 panel pixel. Therefore, according to the second embodiment, the degradation of display quality caused by the time difference in shifting the projection position and the difference in the shift direction can be further suppressed compared to the first embodiment. Also in the second embodiment, signal processing is performed in units of one frame period, so that the configuration can be simplified and the processing load can be reduced compared to the comparative example in which signal processing is performed in units of two frame periods.

[0090] In the above-described first and second embodiments (hereinafter referred to as "embodiments, etc."), various modifications or applications are possible as follows.

[0091] In the embodiment and the like, the liquid crystal panel 100 is of a transmissive type, but it may be of a reflective type. In the embodiment, one frame period is divided into four unit periods. That is, the number k of unit periods included in one frame period is set to "4" as an example. k is not limited to "4" and may be any integer equal to or greater than 3.

[0092] In the embodiment, the shift timing of the light path in the light path shift element 230 is set to the rear end period corresponding to the vertical scanning period in the unit periods f1 to f4, but there may be a time delay. In such a case, for example, the processing circuit 21 may be configured to control the light path shift element in anticipation of the time delay so that the image formed by the liquid crystal panel 100 in the unit period is shifted to the projection position corresponding to the unit period.

[0093] Note that "4", the number of unit periods included in one frame period, is an example of an integer k. Furthermore, the up-down direction is an example of a first direction, and the left-right direction is an example of a second direction. Data specifying the gradation level of video pixel D4 is an example of first video pixel data, data specifying the gradation level of video pixel C4 is an example of second video pixel data, data specifying the gradation level of video pixel D5 is an example of third video pixel data, and data specifying the gradation level of video pixel E3 is an example of fourth video pixel data.

[0094] From the above-mentioned exemplary embodiments, the following aspects can be understood, for example.

[0095] A projection type display device according to one aspect 1 includes a liquid crystal panel having a plurality of panel pixels, a light path shift element that shifts an optical path of projection light projected from the panel pixels and projects it as a projection pixel, and a display control circuit that controls the liquid crystal panel and the light path shift element, wherein a frame period is composed of k (k is an integer of 3 or more) unit periods, one panel pixel among the plurality of panel pixels individually expresses k pieces of video pixel data for each of the k unit periods, and the display control circuit controls a gradation of the video pixel data corresponding to the one panel pixel for each of the k unit periods. a data signal corresponding to the level is supplied to the one panel pixel, and the position of the projection pixel is controlled for the light path shift element to a projection position corresponding to the video pixel data for each of the k unit periods, and when shifting from one projection position corresponding to one video pixel data to another projection position corresponding to another video pixel data among the k video pixel data, the projection pixel is caused to pass through a point other than a straight line connecting the one projection position and the other projection position, and the amount of movement in at least one shift among the k shifts in the frame period is equal to or greater than the width of one panel pixel. According to the projection display device of the first aspect, it is possible to reduce display unevenness, simplify the configuration, and reduce the processing load.

[0096] In a projection display device according to a specific aspect 2 of aspect 1, the k is 4 or greater, the multiple image pixel data are arranged in a matrix state in a first direction and a second direction, and the k pieces of image pixel data corresponding to one panel pixel include first image pixel data, second image pixel data adjacent to the first image pixel data in the first direction, third image pixel data adjacent to the first image pixel data in the second direction, and fourth image pixel data that is not adjacent to the first image pixel data, the second image pixel data, and the third image pixel data.

[0097] In a projection type display device according to a specific aspect 3 of aspect 1, the display control circuit causes the light path shift element not to pass through a point for a shift having the longest straight line distance connecting the projection position of one unit period to the projection position of the next unit period, and causes the light path shift element to pass through the point for a shift having the shortest straight line distance.

[0098] In a projection type display device according to a specific aspect 4 of aspect 3, the shift from the projection position of one unit period to the projection position of the next unit period includes a first shift that does not pass through the point, and a second shift that passes through the point, and the larger of the magnitude of the component along the first direction and the magnitude of the component along the second direction in the vector of the first shift is equal to a first sum of the magnitude of the component along the first direction in the first half vector from the projection position of the one unit period to the point and the magnitude of the component along the first direction in the second half vector from the point to the projection position of the next unit period, or a second sum of the magnitude of the component along the second direction in the first half vector and the magnitude of the component along the second direction in the second half vector.

[0099] In a projection display device according to a fifth specific example of the fourth example, the k is 4, and there are two pairs of the first shift and the second shift.

[0100] 1... projection type display device, 100R, 100G, 100B... liquid crystal panel, 110... pixel circuit, 118... pixel electrode, 120... liquid crystal element, 20... display control circuit, 21... processing circuit, 22R, 22G, 22B... conversion circuit, 230... light path shift element.

Claims

1. A liquid crystal panel having a plurality of panel pixels; a light path shift element that shifts an optical path of the projection light projected from the panel pixel and projects the light as a projection pixel; a display control circuit for controlling the liquid crystal panel and the light path shift element; Including, A frame period is composed of k (k is an integer of 3 or more) unit periods, Among the plurality of panel pixels, one panel pixel individually expresses k pieces of image pixel data for each of the k unit periods; The display control circuit includes: supplying a data signal corresponding to a grayscale level of video pixel data corresponding to the one panel pixel to the one panel pixel for each of the k unit periods; With respect to the light path shift element, controlling the positions of the projection pixels to projection positions corresponding to image pixel data for each of the k unit periods; when shifting from one projection position corresponding to one image pixel data among the k image pixel data to another projection position corresponding to another image pixel data, the projection position is shifted via a point other than a straight line connecting the one projection position and the another projection position; Among the k shifts in the frame period, the amount of movement in at least one shift is equal to or greater than one pixel of the panel.

1. A projection display device comprising:

2. The k is 4 or more. The plurality of image pixel data are arranged in a matrix state in a first direction and a second direction; The k image pixel data corresponding to the one panel pixel are first image pixel data; second image pixel data adjacent to the first image pixel data in the first direction; third image pixel data adjacent to the first image pixel data in the second direction; fourth image pixel data not adjacent to the first image pixel data, the second image pixel data, and the third image pixel data; Including, 2. The projection display device according to claim 1.

3. The display control circuit includes: With respect to the light path shift element, The shift that connects the projection position of one unit period to the projection position of the next unit period along the longest straight line does not pass through the point, The shift with the shortest straight-line distance is made to pass through the point.

2. The projection display device according to claim 1.

4. The shift from the projection position of one unit period to the projection position of the next unit period requires a first shift that does not pass through said location; a second shift through said location; There are In the first shift vector, The larger of the magnitude of the component along the first direction and the magnitude of the component along the second direction is In the second shift vector, A first sum of a magnitude of a component along the first direction of a first half vector from the projection position of the one unit period to the point and a magnitude of a component along the first direction of a second half vector from the point to the projection position of the next unit period, or a second sum of a magnitude of a component of the first half vector along the second direction and a magnitude of a component of the second half vector along the second direction; Matches 4. The projection display device according to claim 3.

5. The k is 4, There are two sets of the first shift and the second shift.

5. The projection display device according to claim 4.

Images