PROJECTION DISPLAY DEVICE AND METHOD FOR CONTROLLING PROJECTION DISPLAY DEVICE

Abstract

To provide a configuration capable of reversing a polarity of adjacent projection pixels in a projection image in a projection-type display device that shifts the projection pixel using a light path shifting element.SOLUTION: In a projection-type display device 1 including a liquid crystal panel 10 where panel pixels Px are arranged in a first direction X and a second direction Y, a polarity of an image signal supplied to each of all panel pixels Px is set to a same polarity in a same unit period sf among a plurality of unit periods sf, and the polarity of the image signal is reversed upon transition from a current frame period N to a next frame period. The polarity of the image signal is reversed when a projection pixel Pi is shifted by a light path shifting element in the first direction X or in the second direction Y upon transition of the unit period sf, and the polarity of the image signal is not reversed when the projection pixel is shifted along a third direction C or a fourth direction D that intersects the first direction X and the second direction Y.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] A liquid crystal panel used in a projection display device has a plurality of pixels, each having a liquid crystal layer between a pixel electrode and a common electrode, arranged in a first direction and a second direction that intersect with each other. The resolution of a liquid crystal panel is determined by the pitch of adjacent pixels, but there is a limit to narrowing the pixel pitch. Therefore, in order to increase the resolution of a projected image, a technology has been proposed in which a light path shift element is used to shift the position at which the projected pixel is viewed every predetermined period (see, for example, Patent Document 1).

[0003] On the other hand, in liquid crystal panels, the liquid crystal layer is easily deteriorated when a direct current component is applied thereto, so polarity inversion driving is often performed in which the voltage applied to the pixel electrodes is alternately switched between a positive polarity on the higher side and a negative polarity on the lower side with respect to the potential of the common electrode. For example, Patent Document 1 proposes polarity inversion for each frame, each unit period, or each subfield. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-52132 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a liquid crystal panel, if all pixels have the same polarity in the same period, flicker is easily visible, so it is preferable to adopt a dot inversion drive in which adjacent pixels have different polarities. However, when the resolution is increased by shifting the projection pixels using a light path shift element as in the technology described in Patent Document 1, even if the dot inversion drive is performed in the liquid crystal panel, a period occurs in which the polarities of adjacent pixels in the first direction and adjacent pixels in the second direction are the same in the projection image. Therefore, in the case of a projection display device that shifts the projection pixels using a light path shift element, it is difficult to invert the polarities of adjacent projection pixels in the projection image with the conventional technology, and flicker is easily visible. [Means for solving the problem]

[0006] In order to solve the above problem, one embodiment of a projection type display device of the present invention includes a liquid crystal panel in which a plurality of panel pixels, each having a liquid crystal layer between a pixel electrode and a common electrode, are arranged in a first direction and a second direction intersecting the first direction; a light path shift element that generates a projection image by shifting a position of a projection pixel, at which light projected from the panel pixel is visible, for each of a plurality of unit periods included in one frame period; and a control unit that controls a timing at which the light path shift element shifts the projection pixel, a direction in which the light path shift element shifts the projection pixel, and an image signal supplied to each of the plurality of panel pixels, wherein the control unit keeps the polarity of the image signal the same within the same unit period among the plurality of unit periods, inverts the polarity of the image signal when transitioning from the current frame period to the next frame period, and inverts the polarity of the image signal when the light path shift element shifts the projection pixel along at least one of a direction parallel to the first direction and a direction parallel to the second direction when transitioning from the current unit period to the next unit period.

[0007] Another aspect of the present invention is a control method for a projection type display device comprising a liquid crystal panel in which a plurality of panel pixels, each having a liquid crystal layer between a pixel electrode and a common electrode, are arranged in a first direction and a second direction intersecting the first direction, and in which a position of a projection pixel at which light projected from the panel pixel is visible is shifted for each of a plurality of unit periods included in a frame period to generate a projection image, the control method comprising the steps of: making the polarity of an image signal supplied to each of the plurality of panel pixels the same within a same unit period among the plurality of unit periods; inverting the polarity of the image signal when transitioning from the current frame period to the next frame period; and inverting the polarity of the image signal when shifting the projection pixel along at least one of a direction parallel to the first direction and a direction parallel to the second direction when transitioning from the current unit period to the next unit period.

[0008] Another aspect of the present invention is a control method for a projection display device having a liquid crystal panel with a liquid crystal layer sandwiched between a pixel electrode and a common electrode, characterized in that light projected from the liquid crystal panel is shifted for each of a plurality of unit periods included in one frame period to generate a projection image, the frame period including a first unit period, a second unit period, a third unit period and a fourth unit period, and in the first unit period and the second unit period, a positive polarity image signal is supplied to the pixel electrode, and in the third unit period and the fourth unit period, a negative polarity image signal is supplied to the pixel electrode. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of the configuration of a projection display device to which the present invention is applied. [Diagram 2] 2 is a block diagram showing an example of the configuration of a control system etc. of the projection display device shown in FIG. [Diagram 3] 3 is a circuit diagram of a pixel circuit corresponding to the panel pixel shown in FIG. 2. [Figure 4] FIG. 3 is an explanatory diagram of the light path shift element shown in FIG. 2 . [Diagram 5] 11A and 11B are explanatory diagrams showing the effect on display resolution caused by shifting projected pixels. [Figure 6] 4 is an explanatory diagram of a unit period in a first operation example of the projection display device shown in FIG. [Figure 7] 4 is an explanatory diagram of a current frame period in the first operation example of the projection display device shown in FIG. [Figure 8] 4 is an explanatory diagram of a next frame period in the first operation example of the projection display device shown in FIG. [Figure 9] 1. FIG. 4 is an explanatory diagram of a current frame period in a second operation example of the projection display device shown in FIG. [Figure 10] 1. FIG. 4 is an explanatory diagram of a next frame period in a second operation example of the projection display device shown in FIG. [Figure 11] 1. FIG. 4 is an explanatory diagram of a unit period in a third operation example of the projection display device shown in FIG. [Figure 12] 1. FIG. 4 is an explanatory diagram of a current frame period in the third operation example of the projection display device shown in FIG. [Figure 13] 1. FIG. 4 is an explanatory diagram of a next frame period in a third operation example of the projection display device shown in FIG. [Figure 14] 5A to 5C are explanatory diagrams showing the influence of a lateral electric field in the first operation example. [Figure 15] 13A and 13B are explanatory diagrams showing the effect on a transverse electric field by the third operation example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described with reference to the drawings. In the following description, of two directions intersecting each other in the in-plane direction of the liquid crystal panel 10, the first direction is labeled X, and the second direction intersecting the first direction X is labeled Y. In addition, the direction intersecting both the first direction X and the second direction Y is labeled third direction C, and the direction intersecting the first direction X and the second direction Y so as to be inclined in the opposite direction to the third direction C is labeled fourth direction D. In addition, the description will be given with X1 labeled on one side of the direction extending parallel to the first direction X, X2 labeled on the other side of the direction extending parallel to the first direction X, Y1 labeled on one side of the direction extending parallel to the second direction Y, and Y2 labeled on the other side of the direction extending parallel to the second direction Y.

[0011] In the present invention, one frame period is a period required for the light path shift element 110 to perform one cycle of repeating the operation of shifting the projection pixels Pi in a predetermined order. Therefore, in the case of the first operation example and the second operation example described later, one frame period corresponds to a period required for displaying one frame of an image. In contrast, as in the case of the third operation example described later, when one frame period includes a first subframe period and a second subframe period, the light path shift element 110 performs one cycle of repeating the operation of shifting the projection pixels Pi in a predetermined order during one frame period, but one frame of an image is displayed during each of the first subframe period and the second subframe period.

[0012] In addition, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the technical scope of the present invention is not limited to these forms unless otherwise specified in the following description to limit the present invention. For example, the combination of directions in which the light path shift element 110 shifts the projection pixel Pi, the order of directions in which the light path shift element 110 shifts the projection pixel Pi, etc. are not limited to the modes exemplified in the first operation example, the second operation example, and the third operation example described later.

[0013] 1. Configuration example of projection type display device 1 FIG. 1 is a block diagram showing an example of the configuration of a projection display device 1 to which the present invention is applied. FIG. 2 is a block diagram showing an example of the configuration of a control system, etc., of the projection display device 1 shown in FIG. 1. FIG. 3 is a circuit diagram of a pixel circuit 40 corresponding to a panel pixel Px shown in FIG. 2. Note that polarizing plates, etc. are omitted from FIG. 1. The projection display device 1 shown in FIG. 1 includes an illumination device 90, a separation optical system 70, three liquid crystal panels 10R, 10G, and 10B, and a projection optical system 60. The liquid crystal panels 10R, 10G, and 10B have a liquid crystal layer disposed between a pair of substrates, and the liquid crystal layer is driven between a pixel electrode formed on one of the pair of substrates and a common electrode formed on the other substrate.

[0014] The illumination device 90 is a white light source, and for example, a laser light source or a halogen lamp is used. The separation optical system 70 includes three mirrors 71, 72, and 75, and dichroic mirrors 73 and 74. The separation optical system 70 separates the white light emitted from the illumination device 90 into the three primary colors of red R, green G, and blue B. Specifically, the dichroic mirror 74 transmits light in the red R wavelength range and reflects light in the green G and blue B wavelength ranges. The dichroic mirror 73 transmits light in the blue B wavelength range and reflects light in the green G wavelength range.

[0015] The light corresponding to red R, green G, and blue B is guided to liquid crystal panels 10R, 10G, and 10B, respectively. The liquid crystal panels 10R, 10G, and 10B are used as spatial light modulators. In the following description, the liquid crystal panels 10R, 10G, and 10B may be collectively referred to as the liquid crystal panel 10.

[0016] The lights modulated by the liquid crystal panels 10R, 10G, and 10B are each incident from three directions onto the dichroic prism 61. The dichroic prism 61 constitutes a synthesis optical system in which red R, green G, and blue B images are synthesized.

[0017] On the side from which light is emitted in the dichroic prism 61, the projection optical system 60 includes a projection lens system 62 and an optical path shift element 110. The optical path shift element 110 is an optical element that shifts the light emitted from the dichroic prism 61 in a predetermined direction. The projection lens system 62 enlarges and projects the composite image emitted from the optical path shift element 110 onto a projection target member such as a screen 80. As a result, a color image is displayed on the projection target member such as the screen 80.

[0018] 2, the projection type display device 1 includes three liquid crystal panels 10 consisting of liquid crystal panels 10R, 10G, and 10B, a control unit 50, a light path shift element driving unit 14, and a light path shift element 110. The control unit 50 and the light path shift element driving unit 14 are configured with electric circuits, but can also be realized as modules executed by a CPU. The liquid crystal panel 10 includes a display unit 30 in which a plurality of panel pixels Px are arranged, and a driving circuit 20 that drives the plurality of panel pixels Px.

[0019] The display section 30 of the liquid crystal panel 10 is formed with s scanning lines 32 extending in a first direction X and t data lines 34 extending in a second direction Y. s and t are positive integers equal to or greater than 2. A plurality of panel pixels Px are arranged in s rows and t columns in the display section 30, corresponding to intersections between the scanning lines 32 and the data lines 34. In this embodiment, the panel pixels Px are disposed at all s×t intersections of the s scanning lines 32 and the t data lines 34. However, the panel pixels Px may be disposed at some of the s×t intersections.

[0020] 2 and 3, the driving circuit 20 includes a scanning line driving circuit 22 and a data line driving circuit 24, and supplies an image signal VD[j] that specifies the grayscale level to be displayed by each of the panel pixels Px to each pixel circuit 40 of the panel pixels Px. j is an integer that satisfies 1≦j≦t. The scanning line driving circuit 22 supplies a scanning signal GS[i] to the scanning line 32 of the i-th row. The scanning line driving circuit 22 selects the scanning line 32 of the i-th row by setting the scanning signal GS[i] to a predetermined selection potential. i is an integer that satisfies 1≦i≦s. The data line driving circuit 24 supplies image signals VD[1] to VD[t] to the data lines 34 of the 1st row to the t-th row in synchronization with the selection of the scanning line 32 by the scanning line driving circuit 22. In other words, the data line driving circuit 24 supplies an image signal VD[j] to the data line of the j-th row.

[0021] The pixel circuit 40 includes a liquid crystal element CL, a selection switch Sw, and a capacitance Co. The liquid crystal element CL is an electro-optical element including a pixel electrode 41, a common electrode 42, and a liquid crystal layer 43 provided between the pixel electrode 41 and the common electrode 42. When a voltage is applied between the pixel electrode 41 and the common electrode 42 in the liquid crystal element CL, the relative transmittance of the liquid crystal element CL changes according to the magnitude of the applied voltage. Then, the panel pixel Px displays a gray scale level according to the relative transmittance of the liquid crystal element CL.

[0022] The relative transmittance of the liquid crystal element CL is a relative value indicating the amount of light transmitted through the liquid crystal element CL. In this embodiment, the amount of light transmitted through the liquid crystal element CL is set to 0% when no voltage is applied to the liquid crystal element CL and the liquid crystal layer 43 is in a state where it is least likely to transmit light. Also, the amount of light transmitted through the liquid crystal element CL is set to 100% when the maximum voltage that can be applied to the liquid crystal element CL is applied and the liquid crystal layer 43 is in a state where it is most likely to transmit light.

[0023] In this embodiment, a case will be described as an example in which the liquid crystal layer 43 of the liquid crystal element CL is of the VA (Vertical Alignment) type, and the panel pixel Px displays black in a normally black mode when no voltage is applied between the pixel electrode 41 and the common electrode 42. The black display means that the relative transmittance of the liquid crystal element CL is 0%.

[0024] The common electrode 42 is set to a predetermined reference potential. One end of the capacitance Co is electrically connected to the pixel electrode 41, and the other end is electrically connected to the capacitance line 36 that is maintained at a constant voltage Vcom. The common electrode 42 is also maintained at the voltage Vcom. The selection switch Sw is, for example, an N-channel transistor. The selection switch Sw is provided between the pixel electrode 41 and the data line 34, and controls the electrical connection state between the pixel electrode 41 and the data line 34, that is, the conductive state and the insulated state. Specifically, the gate of the selection switch Sw, which is an N-channel transistor, is electrically connected to the scanning line 32. Then, when the scanning signal GS[i] is set to the selection potential, the selection switch Sw provided in the pixel circuit 40 of the i-th row is turned on. The pixel circuit 40 in which the selection switch Sw is turned on is supplied with the image signal VD[j] from the data line 34, and a voltage according to the image signal VD[j] is applied to the liquid crystal element CL. As a result, the transmittance of the liquid crystal element CL of the pixel circuit 40 changes in response to the image signal VD[j], and the panel pixel Px corresponding to this pixel circuit 40 displays a grayscale level in accordance with the image signal VD[j].

[0025] After a voltage corresponding to the image signal VD[j] is applied to the liquid crystal element CL of the pixel circuit 40, when the selection switch Sw is turned off, the potential at the pixel electrode 41 is held by the capacitance Co. Therefore, during the period from when the selection switch Sw is turned on until the selection switch Sw is turned on again, the voltage corresponding to the image signal VD[j] continues to be applied to the liquid crystal element CL. Here, when a DC voltage is applied to the liquid crystal element CL, the electrical characteristics deteriorate, causing a so-called burn-in phenomenon. For this reason, in this embodiment, an AC drive is adopted in which the polarity of the potential of the image signal VD[j] is inverted around a predetermined potential. The predetermined potential is, for example, a common potential applied to the common electrode 42. A potential that takes into account the voltage drop caused by the transistor of the selection switch Sw may be adopted as the predetermined potential. When the potential of the image signal VD[j] is higher than the predetermined potential, it is called positive polarity (+), and when the potential of the image signal VD[n] is lower than the predetermined potential, it is called negative polarity (-). In this embodiment, when performing such polarity inversion, a method is adopted in which a predetermined potential is fixed and the polarity of the image signal VD[j] applied to the pixel electrode 41 with respect to the predetermined potential is changed.

[0026] 2 again, the control unit 50 includes an image processing unit 11 and a timing signal generating unit 12. The timing signal generating unit 12 generates a control signal CLT for controlling the driving circuit 20 and the image processing unit 11 based on a synchronization signal supplied from a higher-level device (not shown), and supplies the generated control signal CLT to the driving circuit 20 and the image processing unit 11. The timing signal generating unit 12 generates a polarity signal PL for defining the polarity of the image signal VD[n], and supplies it to the data line driving circuit 24. The data line driving circuit 24 sets the polarity of the image signal VD[n] according to the polarity signal PL. The timing signal generating unit 12 generates a control signal CLD for controlling the light path shift element 110 based on the synchronization signal. When an input video signal Vin representing an image to be displayed by the projection display device 1 is supplied from the higher-level device, the image processing unit 11 generates an output image signal VL indicating the grayscale level of the panel pixel Px in a plurality of unit periods described later based on the input video signal Vin and the control signal CLT. Furthermore, the image processing unit 11 generates a control signal CLU that specifies the shift direction of the light path shift element 110 based on the input video signal Vin, and supplies the control signal CLU to the light path shift element driving unit 14.

[0027] The light path shift element driving unit 14 drives the light path shift element 110 based on the control signal CLD supplied from the timing signal generating unit 12 and the control signal CLU supplied from the image processing unit 11. Therefore, the control unit 50 controls the timing at which the light path shift element 110 shifts the projection pixel Pi, the direction in which the light path shift element 110 shifts the projection pixel Pi, and the image signal VD[j] supplied to each of the multiple panel pixels Px.

[0028] 2. Example of the configuration of the light path shift element and its resolution Fig. 4 is an explanatory diagram of the light path shift element 110 shown in Fig. 2. Fig. 4 illustrates an example in which the position of the projection pixel Pi, at which the light emitted from the panel pixel Px is visible, is shifted by the light path shift element 110 along a direction parallel to the fourth direction D by a distance equivalent to 0.5 pixel pitch (=P / 2) on one side X1 in the first direction X and a distance equivalent to 0.5 pixel pitch (=P / 2) on one side Y1 in the second direction Y. Fig. 4 illustrates a case in which the light path shift element 110 includes a light-transmitting plate, and the light-transmitting plate is swung around one or both of an axis extending in the first direction and an axis extending in the second direction to shift the projection pixel Pi.

[0029] FIG. 5 is an explanatory diagram showing the effect of shifting the projection pixel Pi on the display resolution. FIG. 5 shows only a part of the multiple projection pixels Pi in the projection image 100. Also, FIG. 5 shows only a part of the multiple panel pixels Px of the liquid crystal panel 10. In FIG. 5, in the projection image 100, the first row is denoted as A1, A2, ..., the second row is denoted as B1, B2, ..., and the third row is denoted as C1, C2, ..., for the sake of convenience in distinguishing the projection pixels Pi. Also, in the liquid crystal panel 10 of FIG. 5, the first row is denoted as a1, a2, ..., the second row is denoted as b1, b2, ..., and the third row is denoted as c1, c2, ..., for the sake of convenience in distinguishing the panel pixels Px.

[0030] 4, the light path shift element 110 shifts the projection pixel Pi, in which the light emitted from each of the panel pixels Px of the liquid crystal panel 10 is visible, in a direction controlled by a control signal CLU among a first direction X, a second direction Y, a third direction C, and a fourth direction D for each unit period described later, as the light paths before and after the shift are indicated by dotted lines LA and LB, to generate a projection image 100. In this embodiment, the light path shift element 110 shifts the projection pixel Pi in any of the first direction X, the second direction Y, the third direction C, and the fourth direction D, by a distance equivalent to 1 / 2 of the pixel pitch P in the direction parallel to the first direction X and the direction parallel to the second direction Y.

[0031] Therefore, as shown in FIG. 5, when a projection pixel Pi projected from a panel pixel Px with a reference symbol a1 in the liquid crystal panel 10 is shifted to one side X1 along a direction parallel to the first direction X in the first unit period, to one side Y1 along a direction parallel to the second direction Y in the second unit period, to the other side X2 along a direction parallel to the first direction X in the third unit period, and to the other side Y2 along a direction parallel to the second direction Y in the fourth unit period, a projection pixel Pi projected from one panel pixel a1 is visually recognized at four places surrounded by a thick frame P0. During that time, the gradation of the panel pixel Px is controlled for each unit period. Therefore, when the resolution indicated by the arrangement of the projection pixels Pi in the projection image 100 is the display resolution and the resolution indicated by the arrangement of the panel pixels Px of the liquid crystal panel 10 is the panel resolution, the display resolution is twice the panel resolution in the first direction X and twice the panel resolution in the second direction Y.

[0032] 3. First operation example FIG. 6 is an explanatory diagram of a unit period in a first operation example of the projection display device 1 shown in FIG. 1. FIG. 7 is an explanatory diagram of a current frame period N in a first operation example of the projection display device 1 shown in FIG. 1. FIG. 8 is an explanatory diagram of a next frame period N+1 in a first operation example of the projection display device 1 shown in FIG. 1. In FIG. 7 and FIG. 8, the upper part shows the shift direction by the light path shift element 110 and the projection pixels Pi expressed by the multiple panel pixels Px, the upper part shows the polarities of the multiple panel pixels Px, and the lower part shows the polarities of the panel pixels Px when the multiple projection pixels Pi of the projection image 100 are expressed. Note that in the upper parts of FIG. 7 and FIG. 8, the positions of the nine panel pixels Px in the first unit period sf1-1 are indicated by dotted lines.

[0033] In Fig. 6, among the multiple frame periods, the odd-numbered frame periods are shown as frame period N, and the even-numbered frame periods are shown as frame period N+1. Therefore, after the current frame period N is executed, the next frame period N+1 is executed. Also, after the frame period N+1 ends, the frame period N is executed. Frame period N and frame period N+1 have the same length.

[0034] Each of the frame period N and the frame period N+1 is divided into four unit periods sf consisting of a first unit period sf1, a second unit period sf2, a third unit period sf3, and a fourth unit period sf4. The four unit periods sf have the same length. In Figures 6, 7, and 8, the four unit periods sf in the frame period N and the four unit periods sf in the frame period N+1 are distinguished for convenience as follows: This frame period N First unit period sf1-1 Second unit period sf2-1 3rd unit period sf3-1 4th unit period sf4-1 Next frame period N+1 First unit period sf1-2 Second unit period sf2-2 3rd unit period sf3-2 4th unit period sf4-2

[0035] As shown in Fig. 7, in frame period N, four projection pixels A1, A2, B1, and B2 of the projection image 100 are represented by panel pixel a1 of the liquid crystal panel 10. Also, as shown in Fig. 8, in frame period N+1, four projection pixels A1, A2, B1, and B2 are represented by panel pixel a1 of the liquid crystal panel 10. Other pixels are represented in a similar manner. For example, in frame periods N and N+1, four projection pixels A3, A4, B3, and B4 are represented by panel pixel a2 of the liquid crystal panel 10.

[0036] As shown in Fig. 7 and Fig. 8, in the frame period N and the frame period N+1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch for each unit period sf. In this case, the control unit 50 makes the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px the same in the same unit period sf among the plurality of unit periods sf, and inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px when the light path shift element 110 shifts the projection image in at least one of the direction parallel to the first direction X and the direction parallel to the second direction Y when shifting from the current unit period sf to the next unit period sf in the same frame period N. In addition, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px between the current frame period N and the next frame period N+1.

[0037] In this embodiment, the shift directions by the light path shift element 110 are two directions, a first direction X and a second direction Y.

[0038] More specifically, as shown in FIG. 7, in a frame period N, in a first unit period sf1-1, the control unit 50 sets the polarity of the image signal VD for all of the panel pixels Px to +.

[0039] Next, when transitioning from the first unit period sf1-1 to the second unit period sf2-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from + to -.

[0040] Next, when transitioning from the second unit period sf2-1 to the third unit period sf3-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the second direction Y toward one side Y1 of the second direction Y. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0041] Next, when the third unit period sf3-1 transitions to the fourth unit period sf4-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixels along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from + to -. In this manner, the frame period N ends.

[0042] Next, as shown in FIG. 8, when transitioning from the fourth unit period sf4-1 of the current frame period N to the first unit period sf1-2 of the next frame period N+1, the light path shift element 110 shifts the projection pixel Pi toward the other side Y2 of the second direction Y along a direction parallel to the second direction Y. In this way, when transitioning from the current frame period N to the next frame period N+1, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px between the current frame period N and the next frame period N+1. In this embodiment, since the polarity of the image signal VD was + in the first unit period sf1-1 of the frame period N, when transitioning from the fourth unit period sf4-1 of the frame period N to the first unit period sf1-2 of the frame period N+1, the control unit 50 sets the polarity of the image signal VD to - regardless of in which direction the projection pixel Pi is shifted.

[0043] Next, when transitioning from the first unit period sf1-2 to the second unit period sf2-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0044] Next, when transitioning from the second unit period sf2-2 to the third unit period sf3-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the second direction Y toward one side Y1 of the second direction Y. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from + to -.

[0045] Next, when the third unit period sf3-2 transitions to the fourth unit period sf4-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from - to +. In this manner, the frame period N+1 ends.

[0046] Next, when transitioning from the fourth unit period sf4-2 of the frame period N+1 to the first unit period sf1-1 of the frame period N, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the second direction Y toward the other side Y2 of the second direction Y. In this way, when transitioning from the frame period N+1 to the frame period N, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px between the frame period N and the frame period N+1. In this embodiment, since the polarity of the image signal VD was negative in the first unit period sf1-2 in the frame period N+1, when transitioning from the fourth unit period sf4-1 of the frame period N+1 to the first unit period sf1-1 of the frame period N, the control unit 50 sets the polarity of the image signal VD to positive regardless of the direction in which the projection pixel Pi is shifted. Thereafter, the frame periods N and N+1 are executed alternately. As a result, in the projected image 100, adjacent projected pixels Pi are driven with opposite polarities.

[0047] In this manner, in this embodiment, since the projection pixels Pi are shifted by the light path shift element 110, it is possible to realize a projection image 100 with a resolution higher than the panel resolution. Furthermore, since adjacent projection pixels Pi are driven with opposite polarities in the projection image 100, flickering or the like in the projection image 100 is unlikely to occur. Even in this case, since all of the multiple panel pixels Px are driven with the same polarity within one unit period sf, the load on the image processing unit 11 and the data line driving circuit 24 of the control unit 50 is small.

[0048] 4. Second operation example FIG. 9 is an explanatory diagram of the current frame period N in the second operation example of the projection display device 1 shown in FIG. 1. FIG. 10 is an explanatory diagram of the next frame period N+1 in the second operation example of the projection display device 1 shown in FIG. 1. In FIG. 9 and FIG. 10, the upper part shows the shift direction by the light path shift element 110 and the projection pixels Pi expressed by the multiple panel pixels Px, the upper part shows the polarity of the multiple panel pixels Px, and the lower part shows the polarity of the panel pixels Px when the multiple projection pixels Pi of the projection image 100 are expressed. In addition, the upper part of FIG. 7 and FIG. 8 shows the positions of the nine panel pixels Px in the first unit period sf1-1 with dotted lines. Since the basic configuration of this example is the same as that of the first operation example, detailed description of the common configuration will be omitted, such as describing the unit period sf with reference to FIG. 6.

[0049] In this embodiment, similarly to the first operation example, as shown in Fig. 6, the current frame period N and the next frame period N+1 are each divided into four unit periods sf consisting of a first unit period sf1, a second unit period sf2, a third unit period sf3, and a fourth unit period sf4. In addition, in the frame period N, the four projection pixels A1, A2, B1, and B2 of the projection image 100 are represented by the panel pixel a1. In addition, in the frame period N+1, the four projection pixels A1, A2, B1, and B2 of the projection image 100 are also represented by the panel pixel a1.

[0050] In the present embodiment, the light path shift element 110 shifts the projection pixel Pi for each unit period sf in the frame period N shown in Fig. 9 and the frame period N+1 shown in Fig. 10. In this case, the control unit 50 makes the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px the same in the same unit period sf among the plurality of unit periods sf, and inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px when the light path shift element 110 shifts the projection pixel Pi along at least one of the direction parallel to the first direction X and the direction parallel to the second direction Y when moving from the current unit period sf to the next unit period sf in the same frame period. In addition, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all the panel pixels Px between the current frame period N and the next frame period N+1.

[0051] In this embodiment, the multiple shift directions by the light path shift element 110 include, in addition to the first direction X, a third direction C intersecting both the first direction X and the second direction Y, and a fourth direction D intersecting the first direction X and the second direction Y so as to be inclined toward the opposite side to the third direction C. Here, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the multiple panel pixels Px when the light path shift element 110 shifts the projection pixel Pi along a direction parallel to the first direction X during the same frame period N, but does not invert the polarity of the image signal VD supplied to each pixel electrode 41 of all of the multiple panel pixels Px when the light path shift element 110 shifts the projection pixel Pi along at least one of a direction parallel to the third direction C and a direction parallel to the fourth direction D.

[0052] More specifically, in the frame period N shown in FIG. 9, in the first unit period sf1-1, the control unit 50 sets the polarity of the image signal VD for all of the plurality of panel pixels Px to +.

[0053] Next, when transitioning from the first unit period sf1-1 to the second unit period sf2-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from + to -.

[0054] Next, when transitioning from the second unit period sf2-1 to the third unit period sf3-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward the other side X2 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the third direction C. At that time, the control unit 50 does not invert the polarity of the image signal VD for all of the plurality of panel pixels Px, so the polarity of the image signal VD is −.

[0055] Next, when the third unit period sf3-1 transitions to the fourth unit period sf4-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from - to +. In this manner, the frame period N ends.

[0056] 10, when transitioning from the fourth unit period sf4-1 of the current frame period N to the first unit period sf1-2 of the next frame period N+1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward the other side X2 in the first direction X and the other side Y2 in the second direction Y along a direction parallel to the fourth direction D. In this way, when transitioning from the current frame period N to the next frame period N+1, the control unit 50 inverts the polarity of the image signal VD supplied to the pixel electrodes 41 of all of the plurality of panel pixels Px between the current frame period N and the next frame period N+1. In this embodiment, since the polarity of the image signal VD was + in the first unit period sf1-1 of frame period N, when transitioning from the fourth unit period sf4-1 of frame period N to the first unit period sf1-2 of the next frame period N+1, the control unit 50 sets the polarity of the image signal VD for all of the multiple panel pixels Px to -, regardless of the direction in which the light path shift element 110 shifts the projected image.

[0057] Next, when transitioning from the first unit period sf1-2 to the second unit period sf2-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0058] Next, when transitioning from the second unit period sf2-1 to the third unit period sf3-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward the other side X2 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the third direction C. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is +.

[0059] Next, when transitioning from the third unit period sf3-1 to the fourth unit period sf4-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from + to -. In this manner, the frame period N+1 ends.

[0060] Next, when transitioning from the fourth unit period sf4-2 of the frame period N+1 to the first unit period sf1-1 of the frame period N, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the fourth direction D toward the other side X2 in the first direction X and the other side Y2 in the second direction Y. In this way, when transitioning from the next frame period N+1 to the frame period N, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the multiple panel pixels Px between the frame period N+1 and the frame period N. In this embodiment, since the polarity of the image signal VD was negative in the first unit period sf1-2 of the frame period N+1, when transitioning from the fourth unit period sf4-1 of the frame period N+1 to the first unit period sf1-1 of the frame period N, the control unit 50 sets the polarity of the image signal VD for all the multiple panel pixels Px to positive, regardless of in which direction the projection pixel Pi is shifted. Thereafter, frame period N and frame period N+1 are executed alternately. As a result, in the projected image 100, adjacent projection pixels Pi are driven with opposite polarities.

[0061] In this manner, in this embodiment, since the projection pixels Pi are shifted by the light path shift element 110, it is possible to realize a projection image 100 with a resolution higher than the panel resolution. Furthermore, since adjacent projection pixels Pi are driven with opposite polarities in the projection image 100, flickering or the like in the projection image 100 is unlikely to occur. Even in this case, since all of the multiple panel pixels Px are driven with the same polarity within one unit period sf, the load on the image processing unit 11 and the data line driving circuit 24 of the control unit 50 is small.

[0062] 5. Third operation example FIG. 11 is an explanatory diagram of a unit period in the third operation example of the projection display device 1 shown in FIG. 1. FIG. 12 is an explanatory diagram of the current frame period N in the third operation example of the projection display device 1 shown in FIG. 1. FIG. 13 is an explanatory diagram of the next frame period N+1 in the third operation example of the projection display device 1 shown in FIG. 1. FIG. 14 is an explanatory diagram showing the influence of the horizontal electric field in the first operation example. FIG. 15 is an explanatory diagram showing the effect on the horizontal electric field by the third operation example. In FIG. 11 and FIG. 12, the upper part shows the shift direction by the light path shift element 110 and the projection pixels Pi expressed by the multiple panel pixels Px, the upper part shows the polarities of the multiple panel pixels Px, and the lower part shows the polarities of the panel pixels Px when the multiple projection pixels Pi of the projection image 100 are expressed. In addition, in the upper parts of FIG. 12 and FIG. 13, the positions of the nine panel pixels Px in the first unit period sf1-1 are indicated by dotted lines. The basic configuration of this example is similar to that of the first operation example, and therefore a detailed description of the common configuration will be omitted.

[0063] As shown in FIG. 11, in this embodiment, the current frame period N and the next frame period N+1 are each divided into eight unit periods sf consisting of a first unit period sf1, a second unit period sf2, a third unit period sf3, a fourth unit period sf4, a fifth unit period sf5, a sixth unit period sf6, a seventh unit period sf7, and an eighth unit period sf8. In FIG. 11, FIG. 12, and FIG. 13, the eight unit periods sf in the frame period N and the eight unit periods sf in the frame period N+1 are distinguished as follows for convenience. Also, each of the frame periods N and N+1 includes a first subframe period Na and a second subframe period Nb. Here, the first subframe period Na and the second subframe period Nb of the frame period N are denoted by "-1" for convenience, and the first subframe period Na and the second subframe period Nb of the frame period N+1 are denoted by "-2" for convenience. This frame period N First subframe period Na-1 First unit period sf1-1 Second unit period sf2-1 3rd unit period sf3-1 4th unit period sf4-1 Second subframe period Nb-1 5th unit period sf5-1 6th unit period sf6-1 7th unit period sf7-1 8th unit period sf8-1 Next frame period N+1 First subframe period Na-2 First unit period sf1-2 Second unit period sf2-2 3rd unit period sf3-2 Second subframe period Nb-2 4th unit period sf4-2 5th unit period sf5-2 6th unit period sf6-2 7th unit period sf7-2 8th unit period sf8-2

[0064] In this embodiment, as shown in Fig. 12 and Fig. 13, one frame of an image is displayed in each of the first sub-frame period Na and the second sub-frame period Nb. Here, in each of the first sub-frame period Na and the second sub-frame period Nb, one projection pixel Pi is shifted to n positions during a unit period sf of n (n is an integer equal to or greater than 2), and the region to which the light path shift element 110 shifts one projection pixel Pi is different between the first sub-frame period Na and the second sub-frame period Nb. In this embodiment, n is 4, and one projection pixel Pi is shifted to four positions during four unit periods sf in each of the first sub-frame period Na and the second sub-frame period Nb.

[0065] More specifically, in the frame period N and the next frame period N+1, in the first sub-frame period Na, the panel pixel a1 of the liquid crystal panel 10 represents four projection pixels A1, A2, B1, and B2. In contrast, in the frame period N and the next frame period N+1, in the second sub-frame period Nb, the panel pixel a1 of the liquid crystal panel 10 represents four projection pixels B2, B3, C2, and C3. Therefore, the projection pixel B2 is common between the first sub-frame period Na and the second sub-frame period Nb, but the other projection pixels Pi are different. That is, the area in which the light path shift element 110 shifts one projection pixel Pi is different between the first sub-frame period Na and the second sub-frame period Nb.

[0066] The same is true for the other panel pixels Px. For example, in the first sub-frame period Na in the frame period N and the next frame period N+1, the panel pixel a2 of the liquid crystal panel 10 represents four projection pixels A3, A4, B3, and B4. In contrast, in the second sub-frame period Nb in the frame period N and the next frame period N+1, the panel pixel a2 of the liquid crystal panel 10 represents four projection pixels B4, B5, C4, and C5. Therefore, the projection pixel B4 is common between the first sub-frame period Na and the second sub-frame period Nb, but the other projection pixels Pi are different.

[0067] Furthermore, in the first sub-frame period Na in the frame period N and the next frame period N+1, the panel pixel b1 of the liquid crystal panel 10 represents four projection pixels C1, C2, D1, and D2. In contrast, in the second sub-frame period Nb in the frame period N and the next frame period N+1, the panel pixel b1 of the liquid crystal panel 10 represents four projection pixels D2, D3, E2, and E3. Therefore, the projection pixel D2 is common between the first sub-frame period Na and the second sub-frame period Nb, but the other projection pixels Pi are different.

[0068] In the present embodiment, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch for each unit period sf in the frame period N and the frame period N+1. In this case, the control unit 50 makes the polarity of the image signal VD supplied to each pixel electrode 41 of the plurality of panel pixels Px the same in the same unit period sf among the plurality of unit periods sf, and inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the plurality of panel pixels Px when the light path shift element 110 shifts the projection image in at least one of the directions parallel to the first direction X and the second direction Y when transitioning from the present unit period sf to the next unit period sf in the same frame period N. In addition, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the plurality of panel pixels Px between the present frame period N and the next frame period N+1.

[0069] In this embodiment, similarly to the second operation example, the multiple shift directions by the light path shift element 110 include, in addition to the first direction X, a third direction C intersecting both the first direction X and the second direction Y, and a fourth direction D intersecting the first direction X and the second direction Y so as to be inclined in the opposite direction to the third direction C. Here, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the multiple panel pixels Px when the light path shift element 110 shifts the projection image along a direction parallel to the first direction X during the same frame period N, but does not invert the polarity of the image signal VD supplied to each pixel electrode 41 of the multiple panel pixels Px when the light path shift element 110 shifts the projection image along at least one of a direction parallel to the third direction C and a direction parallel to the fourth direction D.

[0070] More specifically, in the first sub-frame period Na-1 of the frame period N shown in FIG. 12, the control unit 50 sets the polarity of the image signal VD to + in the first unit period sf1-1.

[0071] Next, in the first sub-frame period Na-1, when transitioning from the first unit period sf1-1 to the second unit period sf2-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from + to -.

[0072] Next, in the first sub-frame period Na-1, when transitioning from the second unit period sf2-1 to the third unit period sf3-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward the other side X2 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the third direction C. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is -.

[0073] Next, in the first sub-frame period Na-1, when transitioning from the third unit period sf3-1 to the fourth unit period sf4-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0074] Next, in the frame period N, when transitioning from the fourth unit period sf4-1 of the first sub-frame period Na-1 to the fifth unit period sf5-1 of the second sub-frame period Nb-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward one side X1 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the fourth direction D. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is +.

[0075] Next, in the second sub-frame period Nb-1, when the fifth unit period sf5-1 transitions to the sixth unit period sf6-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from + to -.

[0076] Next, in the second sub-frame period Nb-1, when transitioning from the sixth unit period sf6-1 to the seventh unit period sf7-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward one side X1 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the third direction C. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is −.

[0077] Next, in the second sub-frame period Nb-1, when the seventh unit period sf7-1 transitions to the eighth unit period sf8-1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from - to +. In this manner, the frame period N ends.

[0078] 13, when transitioning from the eighth unit period sf8-1 of the second sub-frame period Nb-1 of the current frame period N to the first unit period sf1-2 of the first sub-frame period Na-1 of the next frame period N+1, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the fourth direction D toward the other side X2 in the first direction X and the other side Y2 in the second direction Y. In this way, when transitioning from the current frame period N to the next frame period N+1, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of all of the plurality of panel pixels Px between the current frame period N and the next frame period N+1. In this embodiment, in the frame period N shown in FIG. 12, the polarity of the image signal VD was + in the first unit period sf1-1, so when transitioning from the eighth unit period sf8-1 of the current frame period N to the first unit period sf1-2 of the first sub-frame period Na-2 of the next frame period N+1, the control unit 50 sets the polarity of the image signal VD for all of the multiple panel pixels Px to -, regardless of the direction in which the projection pixel Pi is shifted.

[0079] Next, in the first sub-frame period Na-2, when transitioning from the first unit period sf1-2 to the second unit period sf2-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0080] Next, in the first sub-frame period Na-2, when transitioning from the second unit period sf2-2 to the third unit period sf3-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the third direction C toward the other side X2 in the first direction X and one side Y1 in the second direction Y. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is +.

[0081] Next, in the first sub-frame period Na-2, when transitioning from the third unit period sf3-2 to the fourth unit period sf4-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward one side X1 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from + to -.

[0082] Next, in the frame period N+1, when transitioning from the fourth unit period sf4-2 of the first sub-frame period Na-2 to the fifth unit period sf5-2 of the second sub-frame period Nb-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the fourth direction D, toward one side X1 in the first direction X and one side Y1 in the second direction Y. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is −.

[0083] Next, in the second sub-frame period Nb-2, when the fifth unit period sf5-2 transitions to the sixth unit period sf6-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the plurality of panel pixels Px from - to +.

[0084] Next, in the second sub-frame period Nb-2, when transitioning from the sixth unit period sf6-2 to the seventh unit period sf7-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch toward one side X1 in the first direction X and one side Y1 in the second direction Y along a direction parallel to the third direction C. At that time, the control unit 50 does not invert the polarity of the image signal VD, so that the polarity of the image signal VD for all of the plurality of panel pixels Px is +.

[0085] Next, in the second subframe period Nb-2, when the seventh unit period sf7-2 transitions to the eighth unit period sf8-2, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the first direction X toward the other side X2 of the first direction X. At that time, the control unit 50 inverts the polarity of the image signal VD for all of the panel pixels Px from + to -. In this manner, the frame period N+1 ends.

[0086] Next, when transitioning from the eighth unit period sf8-2 of the second subframe period Nb-2 of the frame period N+1 to the first unit period sf1-1 of the first subframe period Na-1 of the frame period N, the light path shift element 110 shifts the projection pixel Pi by 0.5 pixel pitch along a direction parallel to the fourth direction D toward the other side X2 in the first direction X and the other side Y2 in the second direction Y. In this way, when transitioning from the next frame period N+1 to the current frame period N, the control unit 50 inverts the polarity of the image signal VD supplied to each pixel electrode 41 of the multiple panel pixels Px between the current frame period N and the next frame period N+1. In this embodiment, in the frame period N+1 shown in FIG. 12, the polarity of the image signal VD is negative in the first unit period sf1-2, so when moving from the eighth unit period sf8-1 of the frame period N+1 to the first unit period sf1-1 of the frame period N, the control unit 50 sets the polarity of the image signal VD for all the panel pixels Px to positive, regardless of the direction in which the projection pixel Pi is shifted. After that, the frame period N and the frame period N+1 are executed alternately. As a result, in the projection image 100, adjacent projection pixels Pi are driven with opposite polarities.

[0087] In this manner, in this embodiment, since the projection pixels Pi are shifted by the light path shift element 110, it is possible to realize a projection image 100 with a resolution higher than the panel resolution. Furthermore, since adjacent projection pixels Pi are driven with opposite polarities in the projection image 100, flickering or the like in the projection image 100 is unlikely to occur. Even in this case, since all of the multiple panel pixels Px are driven with the same polarity within one unit period sf, the load on the image processing unit 11 and the data line driving circuit 24 of the control unit 50 is small.

[0088] As will be described below with reference to Figs. 14 and 15, according to this embodiment, the occurrence of liquid crystal alignment defects due to the horizontal electric field between adjacent panel pixels Px can be suppressed, and the quality of the projection image 100 is high. More specifically, for example, when a panel pixel Px that has been displayed in white is adjacent to a panel pixel Px that has been displayed in black, alignment defects of liquid crystal molecules are likely to occur at the boundary due to the influence of the horizontal electric field. Therefore, in Fig. 5, when the background is white and a black line extending in the first direction X is displayed on the third row, panel pixels b1, b2, ... are displayed in black at the timing when projection pixels C1, C2, ... are displayed, and the other panel pixels Px are displayed in white. In this case, alignment defects due to the horizontal electric field occur between panel pixels b1, b2, ... and panel pixels c1, c2, ....

[0089] As a result, in the first operation example shown in FIG. 14, a black shadow PE0 due to poor alignment appears between the projection pixels C1, C2, ..., in the third row and the projection pixels E1, E2, ..., in the fifth row in the first unit period sf1- and the second unit period sf2-1 of the frame period N. In this state, the black shadow PE0 is not noticeable because it is connected to the projection pixels C1, C2, ..., that display black. However, in the third unit period sf3 of the frame period N, when the projection pixels C1, C2, ..., that display black are no longer displayed, a residual portion PE1 of the black shadow appears in the white background, and a residual portion PE2 of the black shadow remains faintly even in the fourth unit period sf4 of the frame period N. Here, in the case of the first operation example, a similar operation is repeated in the next frame period N+1. For this reason, in the first unit period sf1-2 and the second unit period sf2-2, the residual portion PE2 is connected to the black display projection pixels C1, C2, ..., and is therefore not noticeable, but in the third unit period sf3-2 and the fourth unit period sf4-2, even if the black display projection pixels C1, C2, ..., are no longer displayed, the black shadow residual portions PE1, PE2 are generated in the same location as in the frame period N. Therefore, the black shadow residual portions PE1, PE2 are easily noticeable.

[0090] In contrast, in the third operation example shown in FIG. 15, the light path shift element 110 shifts one projection pixel Pi to different regions in the first subframe period Na-1 and the second subframe period Nb-1 in the frame period N, so that the remaining black shadow portions PE1, PE2 are less noticeable. More specifically, in FIG. 5, when the background is white and a black line extending in the first direction X is displayed in the third row, the panel pixels b1, b2, ... are displayed in black at the timing when the projection pixels C1, C2, ... are displayed, and the other panel pixels Px are displayed in white. In this case, an alignment defect caused by the transverse electric field occurs between the panel pixels b1, b2, ... and the panel pixels c1, c2, .... Therefore, a black shadow PE0 caused by an alignment defect appears between the projection pixels C1, C2, ... in the third row and the projection pixels E1, E2, ... in the first unit period sf1-1 and the second unit period sf2-1 of the subframe period Na-1. In this state, the black shadow PE0 is not noticeable because it is connected to the black display projection pixels C1, C2, .... However, in the third unit period sf3-1 of the first sub-frame period Na-1, the black display projection pixels C1, C2, ... are no longer displayed, so a residual portion PE1 of the black shadow appears on the white background, and a faint residual portion PE2 of the black shadow remains even in the fourth unit period sf4 of the frame period N. This situation is similar to the third operation example shown in FIG.

[0091] However, in this embodiment, to express the projection pixels C1, C2, ..., in the second sub-frame period Nb-1, the panel pixels a1, a2, ..., are set to black display, and the other panel pixels Px are set to white display. As a result, in the first unit period sf1-1 and the second unit period sf2-1 of the second sub-frame period Nb-1, a black shadow PE0 caused by poor alignment appears between the projection pixels C1, C2, ..., in the third row and the projection pixels E1, E2, ..., in the fifth row, but since the black shadow PE0 is connected to the projection pixels C1, C2, ..., which are displayed in black, the black shadow PE0 is not noticeable.

[0092] Furthermore, in the third unit period sf3-1 of the second subframe period Nb-1, the projection pixels C1, C2, ..., which display black, are no longer displayed, so that a residual black shadow portion PE1 appears on the white background, and a faint residual black shadow portion PE2 remains in the fourth unit period sf4 of the frame period N. Even in this case, the alignment defect remains between the panel pixels a1, a2, ... and the panel pixels b1, b2, ... in the liquid crystal panel 10. Therefore, the locations where the residual black shadow portions PE1, PE2 appear are different in the first subframe period Na-1 and the second subframe period Nb-1, so the presence of the residual black shadow portions PE1, PE2 is less noticeable. [Explanation of symbols]

[0093] 1... projection type display device, 10, 10B, 10G, 10R... liquid crystal panel, 11... image processing unit, 12... timing signal generation unit, 14... light path shift element driving unit, 20... driving circuit, 22... scanning line driving circuit, 24... data line driving circuit, 30... display unit, 32... scanning line, 34... data line, 36... capacitance line, 40... pixel circuit, 41... pixel electrode, 42... common electrode, 43... liquid crystal layer, 50... control unit, 60... projection optical system, 61... dichroic prism, 62... projection lens system, 80... screen, 90... lighting device, 100... projected image, 110... light path shift element, P i...projection pixel, C...third direction, D...fourth direction, N, N+1...frame period, X...first direction, CL...liquid crystal element, Y...second direction, Px...panel pixel, PE0...shadow, PE1, PE2...residual portion, VD...image signal, PL...polarity signal, Na-1, Na-2...first subframe period, Nb, Nb-1, Nb-2...second subframe period, sf...unit period, sf1...first unit period, sf2...second unit period, sf3...third unit period, sf4...fourth unit period, sf5...fifth unit period, sf6...sixth unit period, sf7...seventh unit period, sf8...eighth unit period

Claims

1. A plurality of panel pixels each having a liquid crystal layer between a pixel electrode and a common electrode are arranged in a first direction, and liquid crystal panels arranged in a second direction intersecting the first direction; The position of the projection pixel where the light projected from the panel pixel is visible is determined in one frame period. a light path shift element for shifting the light path for each of a plurality of unit periods included therein to generate a projection image; The timing at which the light path shift element shifts the projection pixels, A direction in which the projection pixels are shifted, and an image provided to each of the plurality of panel pixels. A control unit that controls a signal; having The control unit changes the polarity of the image signal during the same unit period among the plurality of unit periods. The frame period is the same as the frame period of the current frame. At the transition from the current unit period to the next unit period, the polarity of the image signal is inverted. When the light path shift element shifts the projection pixel in a direction parallel to the first direction and in a direction parallel to the When shifting along two parallel directions, the polarity of the image signal is inverted; A direction intersecting both the first direction and the second direction is defined as a third direction, and the first direction is defined as a A direction intersecting the second direction so as to be inclined in the opposite direction to the third direction is defined as a fourth direction. When the direction is The control unit controls the optical path shift when transitioning from the current unit period to the next unit period. A light element projects the projection pixel in a direction parallel to the third direction and a direction parallel to the fourth direction. a projection device according to claim 1, wherein the polarity of the image signal is not inverted when the image signal is shifted along the Type display device.

2. 2. The projection display device according to claim 1, The one frame period includes a first unit period, a second unit period, and a , a third unit period, and a fourth unit period, The light path shift element is configured to shift from the first unit period to the second unit period. Shifting the projection pixels toward one side of the first direction along a direction parallel to the first direction. When the second unit period is changed to the third unit period, the the projection pixels are shifted toward the other side in the one direction and toward the one side in the second direction; When the unit period is shifted to the fourth unit period, the The projection pixels are shifted toward one side in the first direction, and the fourth unit period is shifted to the next frame. When the system period shifts to the first unit period, the other side of the first direction is moved along the fourth direction. and shifting the projection pixels toward the other side in the second direction. Display device.

3. 2. The projection display device according to claim 1, The one frame period includes a first unit period, a second unit period, and a , the third unit period, the fourth unit period, the fifth unit period, the sixth unit period, the seventh unit period, and the Includes 8 credit periods, The light path shift element is configured to shift from the first unit period to the second unit period. Shifting the projection pixels toward one side of the first direction along a direction parallel to the first direction. When the second unit period is changed to the third unit period, the the projection pixels are shifted toward the other side in the one direction and toward the one side in the second direction; When the unit period is shifted to the fourth unit period, the The projection pixels are shifted toward one side in a first direction, and the projection pixels are shifted from the fourth unit period to the fifth unit period. When the phase shifts to the phase period, the phase shift is performed along the fourth direction on one side of the first direction and on the other side of the second direction. The projection pixel is shifted toward one side, and the fifth unit period is shifted to the sixth unit period. When the projection is performed, the projection is directed toward the other side of the first direction along a direction parallel to the first direction. The pixel is shifted in the third direction when the sixth unit period is shifted to the seventh unit period. The projection is directed toward one side of the first direction and toward the other side of the first direction along a direction parallel to the first direction. When the seventh unit period is shifted to the eighth unit period, the second the projection pixels are shifted toward the other side of the first direction along a direction parallel to the first direction; When the eighth unit period is shifted to the first unit period of the next frame period, the fourth direction the projection pixel is shifted along the other side of the first direction and the other side of the second direction.

1. A projection display device comprising:

4. 4. The projection display device according to claim 1, The frame period includes a first subframe period and a second subframe period following the first subframe period. a subframe period, The light path shift element is In each of the above, the projection pixel is shifted to n positions during n unit periods (n is an integer of 2 or more). Let it go, In the first subframe period and the second subframe period, the light path shift element 2. A projection display device, comprising: a projection pixel shifting unit for shifting the projection pixel in a direction different from one another;

5. A plurality of panel pixels each having a liquid crystal layer between a pixel electrode and a common electrode are arranged in a first direction, and A liquid crystal panel is provided, the liquid crystal panel being arranged in a second direction intersecting the first direction, and light projected from the panel pixels is projected onto the liquid crystal panel. The position of the projection pixel where the light projected is visually recognized is determined for each of a plurality of unit periods included in one frame period. A control method for a projection display device that generates a projection image by shifting the image, comprising the steps of: The signal is supplied to each of the plurality of panel pixels during the same unit period among the plurality of unit periods. The polarity of the image signal to be input is made the same, and the polarity of the image signal to be input is made the same from the current frame period to the next frame period. When the image signal is shifted to the frame period, the polarity of the image signal is inverted. When the current unit period is shifted to the next unit period, the projection pixel is shifted to the first direction. When the image is shifted along a direction parallel to the first direction, and along a direction parallel to the second direction, Inverts the polarity of the image signal, A direction intersecting both the first direction and the second direction is defined as a third direction, and the first direction is defined as a A direction intersecting the second direction so as to be inclined in the opposite direction to the third direction is defined as a fourth direction. When the direction is When the current unit period is shifted to the next unit period, the projection pixel is shifted to the third direction. When the image is shifted along a direction parallel to the fourth direction, the image is shifted along a direction parallel to the fourth direction. A method for controlling a projection display device, comprising the steps of: not inverting the polarity of an image signal;

6. 6. The method for controlling a projection type display device according to claim 5, The one frame period includes a first unit period, a second unit period, and a , a third unit period, and a fourth unit period, When the first unit period is changed to the second unit period, the first direction is parallel to the first direction. the projection pixel is shifted toward one side of the first direction along the first unit period, When the transition to the third unit period occurs, the other side of the first direction and the The projection pixels are shifted toward one side in the second direction, and the projection pixels are shifted from the third unit period to the fourth unit period. When the phase shifts to the phase shift period, the phase shift is directed toward one side of the first direction along a direction parallel to the first direction. and shifting the projection pixel from the fourth unit period to the first unit period of the next frame period. When the transition occurs between the first direction and the second direction, the second direction is shifted to the other side along the fourth direction.

4. A method for controlling a projection display device, comprising: shifting the projection pixels toward a projection side.

7. 6. The method for controlling a projection type display device according to claim 5, The one frame period includes a first unit period, a second unit period, and a , the third unit period, the fourth unit period, the fifth unit period, the sixth unit period, the seventh unit period, and the Includes 8 credit periods, When the first unit period is changed to the second unit period, the first direction is parallel to the first direction. the projection pixel is shifted toward one side of the first direction along the first unit period, When the transition to the third unit period occurs, the other side of the first direction and the The projection pixels are shifted toward one side in the second direction, and the projection pixels are shifted from the third unit period to the fourth unit period. When the phase shifts to the phase shift period, the phase shift is directed toward one side of the first direction along a direction parallel to the first direction. When the fourth unit period is shifted to the fifth unit period, The projection is directed along the fourth direction toward one side of the first direction and one side of the second direction. The pixel is shifted in the first direction when the fifth unit period is shifted to the sixth unit period. shifting the projection pixels toward the other side of the first direction along a direction parallel to the first direction; When the sixth unit period is shifted to the seventh unit period, the third direction is parallel to the sixth direction. The projection pixels are shifted toward one side in the first direction and toward the other side in the first direction, When the seventh unit period is shifted to the eighth unit period, the second direction is parallel to the eighth direction. and shifting the projection pixel toward the other side in the first direction from the eighth unit period to the next When the transition to the first unit period of the frame period occurs, the first direction is shifted along the fourth direction. the projection pixels are shifted toward the other side and toward the other side in the second direction. A method for controlling a projection display device.

8. 8. The method for controlling a projection display device according to claim 5, further comprising: The frame period includes a first subframe period and a second subframe period following the first subframe period. a subframe period, In each of the first subframe period and the second subframe period, n (n is 2 shifting the projection pixel to n positions during the unit period (n is an integer equal to or greater than n); The projection pixels are shifted in the first subframe period and the second subframe period.

4. A method for controlling a projection display device, comprising: controlling a projection-type display device in which different areas are illuminated.

Images