Projection type display device

Abstract

To reduce costs and virtually increase resolution. [Solution] A display control circuit 20 causes a light path shift element 230 to shift the position of a projection pixel to position R1 in a unit period f1, and to position R4 in the U direction relative to position R1 by unit period f2, and supplies data signals to the panel pixels based on a video pixel A1 in the unit period f1, based on a video pixel B2 in the unit period f2, and based on a video pixel A2 adjacent to the video pixel A1 in the X direction and a video pixel C2 adjacent to the video pixel A1 in the Y direction in a unit period f1a from the unit period f1 to the unit period f2.

Description

[Technical Field]

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

[0002] A technology for artificially increasing the resolution by using a light path shift element is known in a projection display device that projects image light created by a liquid crystal panel or the like onto a screen, etc. 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 on 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 pixel data constituting video data is individually expressed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-71480 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above technology, the light path shift element shifts the light path in two directions, which not only increases the cost of the light path shift element but also complicates the control of the light path shift element. If a light path shift element that shifts the light path in one direction is used, the cost can be reduced, but the resolution cannot be artificially increased compared to when a light path shift element that shifts the light path in two directions is used. [Means for solving the problem]

[0005] A projection display device according to one aspect of the present disclosure includes an electro-optical device having panel pixels that change their optical state in response to a data signal, a light path shift element that shifts an optical path of projection light emitted from the panel pixels to change the position of the projection pixel by the projection light in a third direction that intersects with a first direction and a second direction in which the projection pixels are arranged, and a display control circuit that controls the electro-optical device and the light path shift element, wherein pixel data constituting video data are arranged in the first direction and the second direction in a number greater than the number of the panel pixels, and one frame period includes a first unit period and a second unit period, and the display control circuit controls the light path shift element to shift the optical path of the projection light emitted from the panel pixels in a third direction that intersects with a first direction and a second direction in which the projection pixels are arranged. a light element for shifting a position of the projection pixel to a first position in the first unit period and to a second position in the third direction relative to the first position by the second unit period; the data signal to the panel pixel is supplied based on first pixel data corresponding to the first position in the first unit period, and based on second pixel data corresponding to the second position in the second unit period; and based on third pixel data adjacent to the first pixel data in the first direction and fourth pixel data adjacent to the first pixel data in the second direction during a first period from the first unit period to the second unit period. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a diagram showing a projection display device according to a first embodiment. [Figure 2] FIG. 1 is a block diagram showing a configuration of a projection display device. [Figure 3] 1 is a diagram showing the relationship between the arrangement of video pixels and the 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. [Figure 5] FIG. 10 is a diagram showing a control signal to a light path shift element in a projection display device. [Figure 6] FIG. 10 is a diagram showing a projection position in a unit 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 the electrical configuration of a liquid crystal panel. [Figure 10] FIG. 2 is a diagram showing the configuration of a pixel circuit in a liquid crystal panel. [Figure 11] FIG. 10 is a diagram showing the relationship between video pixels, panel pixels, and projection positions in a unit period. [Figure 12] 1A and 1B are diagrams illustrating examples of display in a projection display device. [Figure 13] FIG. 2 is a diagram showing an image visually recognized by a user in one frame period. [Figure 14] 1A and 1B are diagrams illustrating examples of display in a projection display device. [Figure 15] FIG. 2 is a diagram showing an image visually recognized by a user in one frame period. [Figure 16] FIG. 10 is a diagram showing the relationship between one frame period and a unit period in the second embodiment. [Figure 17] FIG. 10 is a diagram showing a control signal to a light path shift element in a projection display device. [Figure 18] FIG. 11 is a diagram illustrating scaling in the third embodiment. [Figure 19] FIG. 10 is a diagram showing the relationship between one frame period and a unit period in a comparative example. [Figure 20] FIG. 10 is a diagram showing a projection position in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0007] Projection display devices according to embodiments will be described below with reference to the drawings. In each drawing, the dimensions and scale of each part are appropriately different from those of the actual device. The embodiments described below are preferred examples, and therefore various technically preferable limitations are applied. However, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0008] FIG. 1 is a diagram showing the 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 or LED is provided inside the projection display device 1. The 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 input lens 2122, a relay lens 2123, and an output lens 2124 is provided in the optical path of B.

[0009] The liquid crystal panel 100R has a plurality of pixel circuits, as will be described later. 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 exhibit 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 the data signal corresponding to R. Similarly, a G transmission image is generated in the liquid crystal panel 100G based on the data signal corresponding to G, and a B transmission image is generated in the liquid crystal panel 100B based on the 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 that has passed through the optical path shift element 230 onto the screen Scr.

[0011] For convenience of explanation, the rightward direction (backward in the plane of the drawing) of the composite image projected onto the screen Scr is defined as the X direction, the downward direction is defined as the Y direction, and the projection direction by the projection display device 1 (leftward in the plane of the drawing) is defined as the Z direction.

[0012] The light path shift element 230 shifts the light path of the light emitted from the dichroic prism 2112. In detail, the light path shift element 230 shifts the composite image projected onto the screen Scr diagonally in the upper left or lower right direction with respect to the projection surface, as will be described later.

[0013] 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 left-right inverted relative to the transmitted image by the liquid crystal panel 100G.

[0014] 2 is a block diagram showing the 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.

[0015] Source 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 source video data Vid-in specifies the gradation levels of the pixels that make up one frame period of the source video, for example, by 8 bits for each RGB. The synchronization signal Sync includes a vertical synchronization signal that indicates the start of vertical scanning of the source video data Vid-in, a horizontal synchronization signal that indicates the start of horizontal scanning, and a clock signal that indicates the timing of one video pixel in the source video data Vid-in.

[0016] The display control circuit 20 includes a processing circuit 21, conversion circuits 22R, 22G, and 22B, and an enlargement circuit 25. The processing circuit 21 controls the conversion circuits 22R, 22G, and 22B, the magnification circuit 25, the liquid crystal panels 100R, 100G, and 100B, and the light path shift element 230 based on the synchronization signal Sync and in accordance with a unit period, which will be described later.

[0017] In the liquid crystal panels 100R, 100G, and 100B, panel pixels are arranged in a matrix when viewed in a plan view. In this embodiment, pixels specified by the source video data Vid-in correspond one-to-one to panel pixels of the liquid crystal panels 100R, 100G, or 100B. Specifically, when m and n are integers of 2 or more, if the pixels of the source video data Vid-in are arranged in m rows and n columns, the panel pixels are also arranged in m rows and n columns.

[0018] The enlargement circuit 25 enlarges (scales) the pixel array indicated by the source video data Vid-in by two times vertically and two times horizontally, and outputs the result as video data Va-R, Va-G, and Va-B. Note that video data Va-R indicates the R (red) component of the scaled video data. Similarly, video data Va-G indicates the G (green) component of the scaled video data, and video data Va-B indicates the B (blue) component.

[0019] Here, the pixels of an image specified by the video data Vid-R, Vid-G, and Vid-B are referred to as video pixels, and the data specifying the gradation levels of the video pixels are referred to as pixel data, but sometimes the terms video pixels and pixel data are not particularly distinguished from each other. Furthermore, a panel pixel refers to a pixel of an image before or after synthesis by the liquid crystal panel 100R, 100G, or 100B. The position of the panel pixel that is shifted by the light path shift element 230 and projected onto the screen Scr is referred to as the projection position. In this embodiment, the arrangement of video pixels in the video data Vid-R, Vid-G, and Vid-B is (2m) rows and (2n) columns due to scaling, which is four times the number of pixels of the panel pixel arrangement of m rows and n columns, and is twice as large in terms of vertical or horizontal ratio. In this embodiment, the light path shift element 230 simulates image pixels arranged twice as large vertically and twice as large horizontally as the panel pixel arrangement.

[0020] In this embodiment, a color image projected onto the screen Scr is expressed by combining the transmitted images of the liquid crystal panels 100R, 100G, and 100B. Therefore, the smallest 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 of the liquid crystal panels 100R, 100G, and 100B, or when only brightness is an issue, there is no need to refer to them as subpixels. Therefore, in this description, the display units of the liquid crystal panels 100R, 100G, and 100B will also be referred to as panel pixels.

[0021] The conversion circuit 22R temporarily stores the scaled video data Va-R for one or more frame periods in an internal buffer, and then converts the video data read out corresponding to a unit period, or data calculated from the read video data, into an analog voltage data signal Vid_R and supplies it to the liquid crystal panel 100R. The conversion circuits 22G and 22B differ from the conversion circuit 22R only in the color components of the video data to be converted, but are otherwise common to the conversion circuit 22R. That is, the conversion circuit 22G converts the video data Va-G into a data signal Vid_G and supplies it to the liquid crystal panel 100G, and the conversion circuit 22B converts the video data Va-B into a data signal Vid_B and supplies it to the liquid crystal panel 100B.

[0022] FIG. 3 is a diagram for explaining the correspondence between video pixels and panel pixels in the projection display device 1. As shown in FIG. In detail, in Figure 3, the left column shows a portion of the arrangement of image pixels shown in the scaled image data, and the right column shows a portion of the panel pixels that corresponds to the arrangement of the image pixels in the left column.

[0023] In the array in the left column, to distinguish between video pixels in an image represented by scaled video data, the first row is assigned the symbols A1 to A4, the second row is assigned the symbols B1 to B5, the third row is assigned the symbols C1 to C4, and the fourth row is assigned the symbols D1 to D5. Similarly, in the array in the right column of Fig. 3, to distinguish between panel pixels, the first row is assigned the symbols a1 and a2, and the second row is assigned the symbols b1 and b2.

[0024] 4 is a diagram illustrating the relationship between the frame period and the unit period of the projection display device 1 according to the embodiment. As shown in the figure, in this embodiment, one frame (1F) period is divided into six unit periods in terms of time. For convenience, the six unit periods in one frame period are assigned symbols f1, f1a, f1b, f2, f2a, and f2b in chronological order to distinguish them from one another.

[0025] Here, one frame period is the period required to display one frame of the image represented by the source video data Vin, and is 16.7 milliseconds, or one cycle, 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 2.78 milliseconds, which is 1 / 6 of the length of one frame period. 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.

[0026] In this embodiment, the projection position does not move during the unit periods f1 and f2, but changes during the unit periods f1a, f1b, f2a, and f2b. Next, the projection position during each unit period will be described.

[0027] FIG. 5 is a diagram showing an example of the waveform of the control signal P_s supplied to the light path shift element 230, and FIG. 6 is a diagram showing the projection position in one frame (1F) period.

[0028] As shown in FIG. 6, the light path shift element 230 shifts the projection position onto the screen Scr along the U direction and an axis opposite to the U direction relative to the projection surface. The U direction refers to a direction obtained by rotating the X direction by 45 degrees clockwise or the Y direction by 45 degrees counterclockwise. The projection position during a unit period f1 is defined as a reference position P1, and the amount of light path shift is expressed in terms of the size of a panel pixel projected onto the screen Scr. Specifically, half the side (or pitch) of a panel pixel is expressed as 0.5p.

[0029] The projection position is maintained at reference position P1 during unit period f1, and at position P4 during unit period f2. Point P4 is shifted from P1 by 0.5p of panel pixels in the X direction and by 0.5p of panel pixels in the Y direction. In other words, position P4 is shifted from position P1 by 0.707(=1 / √2)p of panel pixels in the U direction.

[0030] The projection position shifts from the reference position P1 to a position P4 from the end timing of the unit period f1 (the start timing of the unit period f1a) to the end timing of the unit period f1b (the start timing of the unit period f2). The projection position also shifts back from position P4 to the reference position P1 from the end timing of unit period f2 (start timing of unit period f2a) to the end timing of unit period f2b (start timing of unit period f1 in the next frame period).

[0031] 6, position P2 indicated by a dashed line indicates the projection position in unit period f1a or f2b, and position P3 indicated by a dashed line indicates the projection position in unit period f1b or f2a. Specifically, position P2 indicates the projection position closer to position P1 among the three positions obtained by equally dividing the shift path from position P1 to position P4. Position P3 indicates the projection position closer to position P4 among the three positions obtained by equally dividing the shift path from position P1 to position P4.

[0032] The light path shift element 230 sets the projection position to position P1 when the level of the control signal P_s is "0," and sets the projection position to position P4 when the level of the control signal P_s is "+A." In this configuration, the processing circuit 21 outputs the level of the control signal P_s as shown in FIG. Specifically, the processing circuit 21 keeps the level of the control signal P_s constant at "0" during the unit period f1, linearly increases the level from the end timing of the unit period f1, and reaches "+A" at the end timing of the unit period f1b. Subsequently, the processing circuit 21 keeps the level of the control signal P_s constant at "+A" during the unit period f2, and linearly decreases the level from the end timing of the unit period f2, and reaches "0" at the end timing of the unit period f2b.

[0033] Furthermore, the processing circuit 21 supplies vertical scanning start pulses Vsync to the liquid crystal panels 100R, 100G, and 100B at the start timings of the unit periods f1, f1a, f1b, f2, f2a, and f2b. The vertical scanning start pulse Vsync is a pulse that instructs the liquid crystal panels 100R, 100G, and 100B to start vertical scanning, and this pulse starts horizontal scanning from row 1. Note that horizontal scanning of the mth row ends before the unit period ends. Therefore, in this embodiment, an image can be generated on the liquid crystal panel 100 for each of the unit periods f1, f1a, f1b, f2, f2a, and f2b.

[0034] Next, liquid crystal panels 100R, 100G, and 100B will be described. Liquid crystal panels 100R, 100G, and 100B have a common structure, with the only difference being the color, or wavelength, of the light incident on them. Therefore, liquid crystal panels 100R, 100G, and 100B will be generally described as liquid crystal panel 100, without specifying the color.

[0035] FIG. 7 is a perspective view showing 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 the electrode forming surfaces face each other while maintaining a certain gap, and liquid crystal 105 is sealed in this gap.

[0036] The element substrate 100a and the counter substrate 100b are each made of a light-transmitting substrate such as glass or quartz. As shown in FIG. 7, one side of the element substrate 100a extends beyond the counter substrate 100b. A plurality of terminals 106 are provided in this extending area 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 various signals described above are supplied.

[0037] 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 element substrate 100a) to efficiently send a large amount of light to the openings that become the panel pixels. With this configuration, light that would have been repelled by the light-shielding portion is sent to the openings of the microlens, thereby improving the light utilization efficiency.

[0038] 9 is a block diagram showing the electrical configuration of the liquid crystal panel 100. The liquid crystal panel 100 has a scanning line driving circuit 130 and a data line driving circuit 140 provided on the periphery of the display area 10.

[0039] In the display region 10 of the liquid crystal panel 100, pixel circuits 110 are arranged in a matrix. More specifically, in the display region 10, m scanning lines 12 are provided extending horizontally in the drawing, and n data lines 14 are provided extending vertically and electrically insulated from the scanning lines 12. The pixel circuits 110 are provided in a matrix at intersections of the m scanning lines 12 and the n data lines 14. Therefore, the pixel circuits 110 are arranged in a matrix of m rows and n columns. In order to distinguish between the rows of the matrix in the scanning lines 12 and the pixel circuits 110, they may be referred to as rows 1, 2, 3, ..., (m-1), m in order from the top in the figure. Similarly, in order to distinguish between the columns of the matrix in the data lines 14 and the pixel circuits 110, they may be referred to as columns 1, 2, 3, ..., (n-1), n ​​in order from the left in the figure.

[0040] The scanning line driving circuit 130 selects the scanning lines 12 one by one in the order of the 1st, 2nd, 3rd, ..., mth rows from the start timing of vertical scanning defined by the vertical scanning start pulse Vsync in accordance with the control of 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 signals to the scanning lines 12 other than the selected scanning line 12 to L level. The data line driving circuit 140 latches the data signals supplied from the corresponding color circuit among the conversion circuits 22R, 22G, or 22B for one row, and outputs them via the data line 14 to the pixel circuit 110 located on that scanning line 12 during the period when the scanning signal to that scanning line 12 is at H level.

[0041] FIG. 10 is a diagram showing an equivalent circuit of four pixel circuits 110 arranged in two rows and two 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 a scan line 12, the source node is connected to a data line 14, and the drain node is connected to a pixel electrode 118 that has a square shape in a plan view.

[0042] 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. As described above, the 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. Furthermore, 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 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 both the vertical and horizontal directions.

[0043] When the scanning signal for a scanning line 12 becomes high, the transistor 116 of the pixel circuit 110 provided corresponding to that scanning line 12 is turned on. When the transistor 116 is turned on, the data line 14 and the pixel electrode 118 are electrically connected, and the data signal supplied to the data line 14 reaches the pixel electrode 118 via the transistor 116 that is turned on. When the scanning line 12 becomes low, the transistor 116 is turned off, but the voltage of the data signal that reaches the pixel electrode 118 is held by the capacitance of the liquid crystal element 120 and the storage capacitor 109.

[0044] 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 of the liquid crystal element 120 that functions as a panel pixel, i.e., the region that exhibits transmittance according to the effective value of the voltage, is the region where the pixel electrode 118 overlaps with the common electrode 108 when the element substrate 100a and the counter substrate 100b are viewed in a plan view. Since the pixel electrode 118 has a square shape in a plan view, the shape of the pixel formed by the liquid crystal panel 100 is also square. In addition, in this 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 its lowest when the voltage applied to the liquid crystal element 120 is zero, and the transmittance increases as the applied voltage increases.

[0045] The operation of supplying data signals to the pixel electrodes 118 of the liquid crystal elements 120 is executed for each unit period f1, f1a, f1b, f2, f2a, and f2b in the order of the 1st, 2nd, 3rd, ..., mth rows. As a result, a voltage corresponding 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 the 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, a transmission image is generated for each of the R, G, and B colors, and a color image obtained by combining the R, G, and B colors is projected onto the screen Scr. The data signals Vid_R, Vid_G, and Vid_B output in a unit period correspond to the RGB components of the video data corresponding to that unit period, so that a composite image of a color corresponding to the projection position is projected at that projection position in that unit period.

[0046] Fig. 11 is a diagram showing which video pixels are represented at which projection positions by panel pixels in the projection display device 1. In detail, the right column of Fig. 11 is a diagram showing at which projection positions the four panel pixels in the right column of Fig. 3 represent the video pixels in the left column of Fig. 3 during unit periods f1, f1a, f1b, f2, f2a, and f2b. Furthermore, the hatched thick frames in the left column of Fig. 11 indicate the video pixels represented by the panel pixels in question.

[0047] Note that a panel pixel expressing a certain video pixel means that the panel pixel has a luminance (brightness) corresponding to the gradation level specified by the pixel data in response to a data signal corresponding to the video pixel. Specifically, this is achieved by the conversion circuit 22 of a certain color converting the video data read out corresponding to a certain unit period, or the data calculated from the read video data, into a data signal and supplying it to the liquid crystal panel 100 corresponding to that color when scanning the panel pixels of that panel.

[0048] As shown in FIG. 11, in unit period f1, panel pixels a1, a2, b1 and b2 sequentially represent hatched video pixels A1, A3, C1 and C3, respectively, at position P1.

[0049] For ease of explanation, unit period f2 will be described in out of chronological order. In unit period f2, panel pixels a1, a2, b1, and b2 represent, in order, hatched video pixels B2, B4, D2, and D4, respectively, at position P4. That is, in unit period f2, panel pixel a1 represents, in position P4, video pixel B2, which is adjacent to video pixel A1 in the U direction, which is the light path shift direction by the light path shift element 230. Similarly, in unit period f2, panel pixels a2, b1, and b2 represent, in order, video pixels B4, C2, and C4, which are adjacent to video pixels A3, C1, and C3 in the U direction, respectively, at position P4.

[0050] In the unit period f1a that follows the unit period f1, the panel pixel a1 expresses a grayscale level based on the video pixel A2 and the video pixel B1. Specifically, in the unit period f1a, the panel pixel a1 expresses a grayscale level that is an average of the grayscale level specified by the video pixel A2 and the grayscale level specified by the video pixel B1. Here, the video pixel A2 is the video pixel adjacent in the X direction to the video pixel A1 expressed by the panel pixel a1 in the unit period f1, and the video pixel B1 is the video pixel adjacent in the Y direction to the video pixel A1. The calculation of the average gray level is performed for each color component in the conversion circuits 22R, 22G, and 22B.

[0051] Similarly, in unit period f1a, panel pixel a2 represents the average gray level between the gray level specified by video pixel A4 and the gray level specified by video pixel B3. In unit period f1a, panel pixel b1 represents the average gray level between the gray level specified by video pixel C2 and the gray level specified by video pixel D1. In unit period f1a, panel pixel b2 represents the average gray level between the gray level specified by video pixel C4 and the gray level specified by video pixel D3. In the unit period f1a, each panel pixel is typically represented by a position P2.

[0052] In the unit period f1b that follows the unit period f1a, the panel pixel a1 expresses a grayscale level based on the video pixel B3 and the video pixel C2. Specifically, in the unit period f1b, the panel pixel a1 expresses a grayscale level that is an average of the grayscale level specified by the video pixel B3 and the grayscale level specified by the video pixel C2. Here, the video pixel B3 is the video pixel adjacent in the X direction to the video pixel B2 expressed by the panel pixel a1 in the unit period f2, and the video pixel C2 is the video pixel adjacent in the Y direction to the video pixel B2.

[0053] Similarly, in unit period f1b, panel pixel a2 represents the average gray level between the gray level specified by video pixel B5 and the gray level specified by video pixel C4. In unit period f1b, panel pixel b1 represents the average gray level between the gray level specified by video pixel D3 and the gray level specified by video pixel E2. In unit period f1b, panel pixel b2 represents the average gray level between the gray level specified by video pixel D5 and the gray level specified by video pixel E4. In the unit period f1b, each panel pixel is typically represented by a position P3.

[0054] In the unit period f2a that follows the unit period f2, the panel pixels a1, a2, b1, and b2 express the same average gray level as in the unit period f1b. In the unit period f2a, each panel pixel is typically expressed at position P3. In the unit period f2b that follows the unit period f2a, the panel pixels a1, a2, b1, and b2 express the same average gray level as in the unit period f1a. Also, in the unit period f2b, each panel pixel is typically expressed at position P2.

[0055] Next, how a specific arrangement of video pixels is viewed by panel pixels in this embodiment will be described.

[0056] The left column of Figure 12 shows an example of a specific example of a video pixel, in which a diagonal line extending upward to the upper right is displayed against a white background. In this case, the diagonal line is a line extending in a direction perpendicular to the U direction, which is the shift direction of the optical path, and video pixels A4, B3, C2, D1, etc. are black, while the others are white. Note that black refers to the minimum gradation level for a certain color, and white refers to the maximum gradation level for a certain color.

[0057] In each unit period, the panel pixels represent video pixels as shown in the right column of Fig. 12. In detail, in unit periods f1a and f2b, black panel pixels are arranged at position P2 in the direction perpendicular to the U direction by panel pixels a2, b1, etc., and in unit periods f1b and f2a, black panel pixels are arranged at position P3 in the direction perpendicular to the U direction by panel pixel a1, etc.

[0058] Fig. 13 is a diagram showing how the panel pixels in the right column of Fig. 12 are perceived by a user over one frame period. When viewed over one frame period, the user sees an image in which black panel pixels arranged along the U direction in unit periods f1a and f2b are superimposed on black panel pixels arranged along the U direction in unit periods f1b and f2a. That is, as shown in the left column of FIG. 12, the video pixels are expressed by overlapping black panel pixels in unit periods f1a and f2b and black panel pixels in unit periods f1b and f2a. Note that the areas where black panel pixels overlap appear relatively dark, and the areas where black panel pixels do not overlap appear relatively bright. In reality, the light-condensing effect of the microlenses, specifically the effect of the panel pixels gradually becoming darker from the center to the periphery, is ignored here.

[0059] In addition to the left column of Fig. 12, the diagonal line going up to the upper right against a white background can also be seen in the form shown in the left column of Fig. 14. That is, this form is a pattern in which the arrangement of video pixels is shifted horizontally by one pixel, and specifically, video pixels A3, B2, C1, etc. are black, and the others are white. In each unit period, the panel pixels represent video pixels as shown in the right column of Fig. 14. In detail, in unit period f1, black panel pixels are arranged at position P1 in a direction perpendicular to the U direction by panel pixels a2, b1, etc., and in unit period f2, black panel pixels are arranged at position P4 in a direction perpendicular to the U direction by panel pixel a1, etc.

[0060] Fig. 15 is a diagram showing how the panel pixels in the right column of Fig. 14 are perceived by a user over one frame period. When viewed over one frame period, the user perceives an image in which black panel pixels arranged along the U direction in unit period f1 and black panel pixels arranged along the U direction in unit period f2 are superimposed.

[0061] The overlapping area of ​​black panel pixels in Figure 13 appears to be smaller than the overlapping area of ​​black panel pixels in Figure 15. However, in Figure 13, the black panel pixels overlap in four of the six unit periods in one frame period: unit periods f1a, f1b, f2a, and f2b. On the other hand, in Figure 15, the black panel pixels overlap in only two of the six unit periods in one frame period: unit periods f1 and f2. For this reason, the overlapping area of ​​black panel pixels in Figure 13 appears darker than the overlapping area of ​​black panel pixels in Figure 15, so the user does not perceive much difference between the two.

[0062] What is important in this embodiment is that even an oblique line along a direction perpendicular to the shift direction of the projection position can be visually recognized by the user. A comparative example will be described to explain the advantages of this embodiment.

[0063] 19 is a diagram showing the relationship between one frame period and unit periods in a comparative example, in which one frame (1F) period is divided into two unit periods: a preceding unit period f1 and a following unit period f2.

[0064] 20 is a diagram showing the projection positions during one frame period in a comparative example. In the comparative example, the optical path is shifted between two positions: position P1 during unit period f1, and position P2, which is shifted diagonally downward to the right in the U direction from position P1 by 0.707p in panel pixels. In the comparative example, the panel pixels are shifted by two positions, so the number of image pixels that can be pseudo-expressed is twice the number of panel pixels, which is 1.414 (=√2) times the number of vertical or horizontal arrays. For this reason, when the pixel data that makes up the video data is supplied in one-to-one correspondence with the panel pixels, a method is used in which the video pixel array is scaled (up-converted) by √2 times vertically and √2 times horizontally before being expressed using the panel pixels. However, since √2 is an irrational number and not an integer, an error occurs in the calculation when scaling. This error causes a decrease in display quality. For example, if the arrangement of image pixels shown in the image data shows a diagonal line perpendicular to the shift direction of the optical path, scaling by √2 times vertically and √2 times horizontally may cause the diagonal line to appear discontinuous or the gradation levels to appear uneven.

[0065] In contrast to this, according to this embodiment, the video pixel array is simply scaled twice as large vertically and twice as large horizontally as the panel pixel array, so that errors that occur in the calculations during scaling can be suppressed. Furthermore, according to this embodiment, the diagonal lines perceived by the user are perceived as a regular pattern as shown in Figure 13 or Figure 15, and are therefore not perceived as discontinuous or with uneven gradation levels.

[0066] In this embodiment, in unit periods f1a and f2b in the process of transition from one of positions P1 and P4 to the other, a certain panel pixel is represented based on the video pixel adjacent in the X direction and the video pixel adjacent in the Y direction to the video pixel represented at position P1. Similarly, in unit periods f1b and f2a in the process of transition, a certain panel pixel is represented based on the video pixel adjacent in the X direction and the video pixel adjacent in the Y direction to the video pixel represented at position P4. This eliminates the drawback that diagonal lines along the U direction, which is orthogonal to the shift direction of the optical path, are difficult to see. That is, according to this embodiment, even when diagonal lines are arranged in the image pixels in a direction orthogonal to the shift direction, the shift of the panel pixels allows the user to see the diagonal lines without losing information about them.

[0067] When the arrangement of video pixels is scaled twice vertically and twice horizontally compared to the arrangement of panel pixels, if the light path shift element 230 is a type that shifts on two axes rather than a type that shifts on one axis, it is possible to represent each video pixel with a panel pixel. In more detail, if one frame period is divided into four unit periods, and in the four unit periods, for example, panel pixel a1 represents video pixels A1, A2, B2, and B1 in that order, and the projection positions are set to the reference position, a position shifted by 0.5p in the X direction, a position shifted by 0.5p in the Y direction, a position shifted by 0.5p in the opposite direction of the X direction, and then returned to the position shifted by 0.5p in the opposite direction of the Y direction (reference position), then it is possible to represent video pixels with panel pixels. However, in this configuration, the light path shift element 230 needs to be a type that shifts in two directions, which not only increases costs but also complicates the control of the light path shift element 230 by the processing circuit 21. In contrast to this, in this embodiment, the light path shift element 230 is of a type that shifts in one direction, so that not only can costs be reduced but also the control of the light path shift element 230 by the processing circuit 21 can be simplified.

[0068] Next, a projection type display device 1 according to a second embodiment will be described. The second embodiment has the same optical configuration as the first embodiment, but differs in the configuration of the unit period in one frame period and the light path shift in the light path shift element 230. Therefore, the second embodiment will be described with emphasis on the unit period and the light path shift, which are the differences from the first embodiment.

[0069] 16 is a diagram illustrating the relationship between the frame period and the unit period of the projection display device 1 according to the second embodiment. As shown in the diagram, the second embodiment is similar to the first embodiment in that one frame (1F) period is divided into six unit periods f1, f1a, f1b, f2, f2a, and f2b in time. However, the second embodiment differs from the first embodiment in that the unit periods are not continuous in time, but are discontinuous with a period T between them to separate them in time.

[0070] FIG. 17 is a diagram showing an example of the waveform of the control signal P_s supplied to the light path shift element 230 in the second embodiment. In the second embodiment, the level of the control signal P_s is constant at "0" in unit period f1, constant at "+A / 3" in unit periods f1a and f2b, constant at "+2A / 3" in unit periods f1b and f2a, and constant at "+A" in unit period f2. The level of the control signal P_s changes from the level of the temporally preceding unit period to the level of the temporally succeeding unit period during period T.

[0071] In the second embodiment, the display control circuit 20 outputs a vertical scanning start pulse Vsync at the start timing of the unit periods f1, f1a, f1b, f2, f2a and f2b, causing the liquid crystal panels 100R, 100G and 100B to complete vertical scanning within the unit period.

[0072] In the first embodiment, the projection position by the light path shift element 230 is shifted in the unit periods f1a, f1b, f2a, and f2b. In contrast, in the second embodiment, the projection positions by the light path shift element 230 are fixed at positions P2, P3, P3, and P2, respectively, in the unit periods f1a, f1b, f2a, and f2b. Therefore, the image pixels represented by the panel pixels in the unit periods f1a, f1b, f2a, and f2b are visually recognized by the user without blurring. Therefore, in the second embodiment, it is possible to improve the visibility of the image pixels represented in the unit periods f1a, f1b, f2a, and f2b compared to the first embodiment.

[0073] In the first embodiment, the source video data is scaled twice vertically and twice horizontally with respect to the panel pixel array and used as video data, but other configurations are also applicable. Therefore, a third embodiment will be described in which the relationship between the pixels constituting the source video data and the panel pixels is not one-to-one.

[0074] FIG. 18 is a diagram for explaining the relationship between source video data and panel pixels in the third embodiment. In the third embodiment, the number of pixels constituting the source video data is twice the number of panel pixels, and in detail, it is necessary to scale it vertically by √2 times and horizontally by √2 times and thin out every other pixel before displaying it. In the third embodiment, since four states are possible, it is not necessary to scale it vertically by √2 times and horizontally by √2 times.

[0075] As a result, the video pixels are twice as large vertically and twice as large horizontally as the panel pixels. Therefore, in the following embodiments, by expressing the video pixels at positions R1, R2, R3, and R4 in each unit period as in the first or second embodiment, it is possible to eliminate the drawback that diagonal lines, particularly those perpendicular to the shift direction of the optical path, are difficult to see.

[0076] The first to third embodiments (hereinafter referred to as "embodiments") described above can be modified in various ways. Specific examples of modifications that can be applied to the embodiments are shown below. Two or more embodiments arbitrarily selected from the following examples may be combined to the extent that they are not mutually contradictory.

[0077] In the embodiments, the source video data is upscaled and converted into video data, and the video data read out corresponding to a unit period, or the data obtained by calculating the read video data, is converted into an analog voltage data signal. If the pixels that make up the source video data are arranged twice as large vertically and twice as large horizontally as the panel pixels, then such source video data can be used as is as video data without being upscaled.

[0078] In the embodiments, for example, panel pixel a1 expresses the average gray level of the gray level specified by video pixel A2 and the gray level specified by video pixel B1 in unit period f1a, and expresses the same averaged gray level in unit period f2b. The advantages of averaging in this manner will be described below. Here, even if the weight of video pixel A2 represented by panel pixel a1 in unit period f1a is set to "3" and the weight of video pixel B1 is set to "1", and the weight of video pixel A2 represented by panel pixel a1 in unit period f2b is set to "1" and the weight of video pixel B1 is set to "3", over the course of one frame period, the weight of video pixel A2 represented by panel pixel a1 and the weight of video pixel B1 will be the same. However, since the weight of one video pixel differs between unit periods, this will be perceived as flicker. In more detail, if panel pixel a1 has a configuration in which the weight of video pixel A2 expressed by panel pixel a1 in unit period f1a is set to "3" and the weight of video pixel A2 expressed by panel pixel a1 in unit period f2b is set to "1," the difference in weight will be perceived by the user as flicker. In other words, by averaging as in the embodiment, the weights of the same image pixel represented by a panel pixel in two unit periods in one frame period are made uniform, thereby preventing the pixel from being perceived as flicker.

[0079] In the embodiment, the shift direction of the optical path is the diagonally downward right (diagonally upward left) direction, but it may be the diagonally downward left (diagonally upward right) direction. In the embodiment, the liquid crystal panel 100 is a transmissive type, but it may be a reflective type.

[0080] In the embodiments, a liquid crystal panel 100 is used as an example of an electro-optical device, but the electro-optical panel may be an electro-optical panel that uses OLEDs (Organic Light Emitting Diodes), inorganic light emitting diodes, LEDs (Light Emitting Diodes), etc. as display elements for the panel pixels, specifically, an electro-optical panel that emits light in response to a data signal.

[0081] From the above-described exemplary embodiments, the following aspects can be understood, for example.

[0082] A projection display device according to a first aspect includes an electro-optical device having panel pixels that are set to an optical state according to a data signal; a light path shift element that shifts an optical path of projection light emitted from the panel pixels to change a position of the projection pixel by the projection light in a third direction that intersects with a first direction and a second direction in which the projection pixels are arranged; and a display control circuit that controls the electro-optical device and the light path shift element, wherein pixel data constituting video data are arranged in the first direction and the second direction in a number greater than the number of the panel pixels, and one frame period includes a first unit period and a second unit period, and the display control circuit controls the light path shift element to shift an optical path of the projection light emitted from the panel pixels to change a position of the projection pixel by the projection light in a third direction that intersects with a first direction and a second direction in which the projection pixels are arranged. The position of the projection pixel is set to a first position in the first unit period for the element, and is shifted to a second position in the third direction relative to the first position by the second unit period, and the data signal to the panel pixel is supplied based on first pixel data corresponding to the first position in the first unit period, and based on second pixel data corresponding to the second position in the second unit period, and based on third pixel data adjacent to the first pixel data in the first direction and fourth pixel data adjacent to the first pixel data in the second direction during a first period from the first unit period to the second unit period.

[0083] According to the projection display device of aspect 1, a light path shift element with a light path shift direction in one direction is used, allowing the user to view an image with pseudo-high resolution with minimal loss of information. The X direction is an example of a "first direction," the Y direction is an example of a "second direction," and the U direction is an example of a "third direction." The transmittance or reflectance of a liquid crystal element is an example of an "optical state." The unit period f1 is an example of a "first unit period," the unit period f2 is an example of a "second unit period," the position P1 is an example of a "first position," the position P4 is an example of a "second position," and the unit period f1a is an example of a "first period." The video pixel A1 is an example of "first pixel data," the video pixel B2 is an example of "second pixel data," the video pixel A2 is an example of "third pixel data," and the video pixel B1 is an example of "fourth pixel data."

[0084] In a projection display device according to a specific aspect 2 of aspect 1, the display control circuit supplies, during a second period from the first unit period to the second unit period, which is after the first period, fifth pixel data adjacent to the second pixel data in the first direction and sixth pixel data adjacent to the second pixel data in the second direction. According to the second aspect, it is possible to reduce the amount of missing video data. The unit period f1b is an example of a "second period", the video pixel B3 is an example of a "fifth pixel data", and the video pixel C2 is an example of a "third pixel data".

[0085] In a projection display device relating to a specific aspect 3 of aspect 2, the light path shift element changes the position of the projection pixel in the third direction or the direction opposite to the third direction, and the display control circuit causes the light path shift element to shift the position of the projection pixel to a second position in the second unit period and to the first position by the first unit period in the next frame period, and supplies the data signal to the panel pixel based on the fifth pixel data and the sixth pixel data in a third period from the second unit period to the first unit period in the next frame period, and supplies the data signal based on the third pixel data and the fourth pixel data in a fourth period from the second unit period to the first unit period in the next frame period, which is after the third period. According to aspect 3, the panel pixels have the same expression during the first period on the outward path of the light path shift element and the fourth period on the return path, and the panel pixels have the same expression during the second period on the outward path of the light path shift element and the third period on the return path. The unit period f2a is an example of a "third period," and the unit period f2b is an example of a "fourth period."

[0086] In a projection display device according to a specific aspect 4 of aspect 3, the display control circuit supplies the data signal to the panel pixel during the first period in accordance with an average gray level of the gray level specified by the third pixel data and the gray level specified by the fourth pixel data, and supplies the data signal to the panel pixel during the fourth period in accordance with the average gray level.

[0087] In a projection display device according to a fifth specific aspect of the first aspect, two vertical and two horizontal arrays of the pixel data correspond to one of the panel pixels.

[0088] A projection display device according to a sixth specific aspect of the first aspect further comprises an enlargement circuit that scales source video data and converts it into the video data.

[0089] In a projection display device according to a specific aspect 7 of aspect 1, the display control circuit causes the light path shift element to continuously shift the position of the projection pixel over time from the first position in the first unit period to the second position in the second unit period.

[0090] In a projection display device according to another specific aspect 8 of aspect 1, the display control circuit causes the light path shift element to discontinuously shift the position of the projection pixel from the first position in the first unit period to the second position in the second unit period. [Explanation of symbols]

[0091] 1...projection 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, 25...magnification circuit, 230...light path shift element

Claims

1. an electro-optical device having panel pixels that change their optical state in response to a data signal; a light path shift element that shifts an optical path of the projection light emitted from the panel pixel to change the position of the projection pixel by the projection light in a third direction that intersects with the first direction and the second direction in which the projection pixels are arranged; a display control circuit that controls the electro-optical device and the light path shift element; Including, pixel data constituting video data are arranged in the first direction and the second direction in a number greater than the number of panel pixels; One frame period includes a first unit period and a second unit period, The display control circuit includes: The position of the projection pixel relative to the light path shift element is a first position in the first unit period, and a second position in the third direction relative to the first position by the second unit period; the data signals to the panel pixels, supplying the first pixel data corresponding to the first position in the first unit period; supplying the second pixel data corresponding to the second position in the second unit period; In a first period from the first unit period to the second unit period, supplying the pixel data based on third pixel data adjacent to the first pixel data in the first direction and fourth pixel data adjacent to the first pixel data in the second direction; Projection type display device.

2. The display control circuit includes: In a second period that is a period from the first unit period to the second unit period and that is after the first period, supplying the pixel data based on fifth pixel data adjacent to the second pixel data in the first direction and sixth pixel data adjacent to the second pixel data in the second direction; 2. The projection display device according to claim 1.

3. The light path shift element is changing the position of the projection pixel in the third direction or in a direction opposite to the third direction; The display control circuit includes: The position of the projection pixel is shifted relative to the light path shift element. the second position in the second unit period, and shifting the second position to the first position by the first unit period in the next one frame period; the data signals to the panel pixels, In a third period from the second unit period to the first unit period in the next one frame period, based on the fifth pixel data and the sixth pixel data; In a fourth period that is a period from the second unit period to the first unit period in the next one frame period and that is after the third period, supplying based on the third pixel data and the fourth pixel data; 3. The projection display device according to claim 2.

4. The display control circuit includes: The data signal to the panel pixel in the first period, supplying the third pixel data corresponding to an average gray level of the gray level designated by the fourth pixel data; In the fourth period, the data signal to the panel pixel is supplying the signal in accordance with the average gray level; 4. The projection display device according to claim 3.

5. Two vertical and two horizontal arrays of the pixel data correspond to one of the panel pixels.

2. The projection display device according to claim 1.

6. and an enlargement circuit for scaling the source video data to convert it into said video data.

2. The projection display device according to claim 1.

7. The display control circuit includes: The position of the projection pixel is shifted relative to the light path shift element. Shifting the position continuously in time from the first position in the first unit period to the second position in the second unit period.

2. The projection display device according to claim 1.

8. The display control circuit includes: The position of the projection pixel is shifted relative to the light path shift element. Shifting the position from the first position in the first unit period to the second position in the second unit period discontinuously in time.

2. The projection display device according to claim 1.

Images