Patent Grant
11804158
The present application is based on, and claims priority from JP Application Serial Number 2021-088219, filed May 26, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a projection-type display device, and a control method for a projection-type display device.
In liquid crystal panels used for projection-type display devices, a plurality of pixels provided with a liquid crystal layer between a pixel electrode and a common electrode are disposed in a first direction and a second direction that intersect each other. The resolution of a liquid crystal panel is defined by the pitch of adjacent pixels, but the reduction of the pitch of pixels is limited. In view of this, for the purpose of increasing the resolution of the projection image, a technique in which the position where the projection pixel is visually recognized is shifted for each predetermined period by using a light path shifting element is proposed (see, for example, JP-A-2020-52132).
On the other hand, since application of a DC component to a liquid crystal layer in a liquid crystal panel tends to cause degradation, a polarity inversion drive that alternately switches the voltage applied to the pixel electrode between a positive polarity on the high side and a negative polarity on the low side relative to the potential of the common electrode is often performed. For example, JP-A-2020-52132 proposes to reverse the polarity for each frame, each unit period, or each subfield.
If all pixels are set to the same polarity in the same period in a liquid crystal panel, flicker tends to be visually recognized, and it is therefore preferable to employ dot reverse driving in which the polarity differs between adjacent pixels. However, in the case where the resolution is increased by shifting the projection pixel by using a light path shifting element as in the technique disclosed in JP-A-2020-52132, there are periods in which the polarity is the same between adjacent pixels in the first direction and between adjacent pixels in the second direction in the projected image even when the dot reverse driving is performed in the liquid crystal panel. Therefore, in the case of the projection-type display device that shifts the projection pixel by using the light path shifting element, it is difficult for the known technology to reverse the polarity of adjacent projection pixels in the projection image, and flicker tends to be visually recognized.
To solve the above-mentioned problems, a projection-type display device according to an aspect of the present disclosure includes a liquid crystal panel including a plurality of panel pixels including a liquid crystal layer between a pixel electrode and a common electrode is arranged in a first direction and a second direction that intersects the first direction, a light path shifting element configured to generate a projection image by shifting, for each of a plurality of unit periods included in one frame period, a position of a projection pixel where light projected from the panel pixel is visually recognized, and a control unit configured to control a timing when the light path shifting element shifts the projection pixel, a direction in which the light path shifting element shifts the projection pixel, and an image signal supplied to each of the plurality of panel pixels. The control unit sets a polarity of the image signal to a same polarity in a same unit period among the plurality of unit periods, reverses the polarity of the image signal upon transition from a current frame period to a next frame period, and reverses the polarity of the image signal when the light path shifting element shifts the projection pixel along at least one of a direction parallel to a first direction and a direction parallel to a second direction that intersects the first direction upon transition from a current unit period to a next unit period.
A control method according to another aspect of the present disclosure is a method for a projection-type display device, the projection-type display device including a liquid crystal panel including a plurality of panel pixels including a liquid crystal layer between a pixel electrode and a common electrode is arranged in a first direction and a second direction that intersects the first direction, the projection-type display device being configured to generate a projection image by shifting, for each of a plurality of unit periods included in one frame period, a position of a projection pixel where light projected from the panel pixel is visually recognized. A polarity of the image signal supplied to each of the plurality of panel pixels is set to a same polarity in a same unit period among the plurality of unit periods, the polarity of the image signal is reversed upon transition from a current frame period to a next frame period, and the polarity of the image signal is reversed when the projection pixel is shifted along at least one of a direction parallel to a first direction and a direction parallel to a second direction that intersects the first direction upon transition from a current unit period to a next unit period.
A control method according to another aspect of the present disclosure is a method for a projection-type display device, the projection-type display device including a liquid crystal panel including a liquid crystal layer sandwiched between a pixel electrode and a common electrode. A projection image is generated by shifting, for each of a plurality of unit periods included in one frame period, light projected from the liquid crystal panel, the frame period includes a first unit period, a second unit period, a third unit period and a fourth unit period, an image signal of a positive polarity is supplied to the pixel electrode in the first unit period and the second unit period, and an image signal of a negative polarity is supplied to the pixel electrode in the third unit period and the fourth unit period.
An embodiment of the present disclosure is described below with reference to the accompanying drawings. Of two directions intersecting each other in the in-plane direction of a liquid crystal panel 10, the first direction is denoted with X and the second direction that intersects the first direction X is denoted with Y in the following description. In addition, the direction that intersects both of the first direction X and the second direction Y is a third direction C, and the direction that obliquely intersects the first direction X and the second direction Y on the side opposite to the third direction C is a fourth direction D in the following description. In addition, one of the directions extending parallel to the first direction X is denoted with X1, the other of the directions extending parallel to the first direction X is denoted with X2, one of the directions extending parallel to the second direction Y is denoted with Y1, and the other of the directions extending parallel to the second direction Y is denoted with Y2 in the following description.
In the present disclosure, one frame period is a period required for a light path shifting element 110 to perform one cycle of repetition of the operation of shifting a projection pixel Pi in a predetermined order. Accordingly, in a first exemplary operation and a second exemplary operation described later, one frame period corresponds to a period required for displaying one frame of an image. On the other hand, in the case where one frame period includes a first subframe period and a second subframe period as in a third exemplary operation described later, the light path shifting element 110 performs the repetition of the operation of shifting the projection pixel Pi in a predetermined order for one cycle during one frame period, while one frame of an image is displayed in each of the first subframe period and the second subframe period.
In addition, the embodiment described below is a specific preferable example of the present disclosure, and therefore has various technically favorable limitations. However, the technical scope of the present disclosure is not limited to these embodiments unless otherwise stated in the following description to limit the present disclosure. For example, the combination of directions in which the light path shifting element 110 shifts the projection pixel Pi, the order of the directions in which the light path shifting element 110 shifts the projection pixel Pi, and the like are not limited to the modes exemplified in the first exemplary operation, the second exemplary operation, and the third exemplary operation described below.
The illumination device 90 is a white light source, and a laser light source or a halogen lamp is used for it, for example. The separation optical system 70 includes three mirrors 71, 72 and 75, and dichroic mirrors 73 and 74. The separation optical system 70 separates white light emitted from the illumination device 90 into three primary colors, namely, red R, green G and blue B. More specifically, the dichroic mirror 74 transmits light of the wavelength range of red R, and reflects light of the wavelength ranges of green G and blue B. The dichroic mirror 73 transmits light of the wavelength range of blue B, and reflects light of the wavelength range of green G.
Light corresponding to red R, green G, and blue B is guided to the liquid crystal panels 10R, 10G and 10B, respectively. The liquid crystal panels 10R, 10G and 10B are used as a spatial light modulator. In the following description, the liquid crystal panels 10R, 10G and 10B may be collectively referred to as the liquid crystal panel 10.
Light modulated by the liquid crystal panels 10R, 10G and 10B impinges on a dichroic prism 61 from three directions. The dichroic prism 61 makes up a composite optical system that combines images of red R, green G, and blue B.
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 the light path shifting element 110. The light path shifting element 110 is an optical element that shifts light emitted from the dichroic prism 61, in a predetermined direction. The projection lens system 62 projects a composite image emitted from the light path shifting element 110, on a projection target member such as a screen 80 in an enlarged manner. As a result, a color image is displayed on the projection target member such as the screen 80.
As illustrated in
In the display unit 30 of the liquid crystal panel 10, s scan lines 32 extending in the first direction X, and t data lines 34 extending in the second direction Y are formed. Each of s and t is a positive integer of two or greater. In the display unit 30, a plurality of the panel pixels Px are arranged in vertical s rows×horizontal t columns in a manner corresponding to the intersections of the scan line 32 and the data line 34. In this embodiment, the panel pixels Px are disposed at all s×t intersections of the s scan lines 32 and the t data lines 34. It should be noted that the panel pixels Px may be disposed at some of s×t intersections.
In
The pixel circuit 40 includes a liquid crystal element CL, a selection switch Sw, and a capacity Co. The liquid crystal element CL is an electrooptic element including a pixel electrode 41, a common electrode 42, and the liquid crystal layer 43 provided between the pixel electrode 41 and the common electrode 42. In the liquid crystal element CL, when a voltage is applied between the pixel electrode 41 and the common electrode 42, the relative transmittance of the liquid crystal element CL changes in accordance with the value of the applied voltage. Then, the panel pixel Px displays a gradation level corresponding to the relative transmittance of the liquid crystal element CL.
The relative transmittance of the liquid crystal element CL is a relative value representing the quantity of light transmitted through the liquid crystal element CL. In this embodiment, the quantity of light that is transmitted through the liquid crystal element CL in the state where no voltage is applied to the liquid crystal element CL and the liquid crystal layer 43 is least permeable to light is 0%. In addition, the quantity of light that is transmitted through the liquid crystal element CL in the state where the maximum voltage that can be applied to the liquid crystal element CL is applied and the liquid crystal layer 43 is most permeable to light is 100%.
This embodiment describes an exemplary case where the liquid crystal layer 43 provided in the liquid crystal element CL is of a vertical alignment (VA) type, and the mode is a normally black mode in which the panel pixel Px is black display in the state where 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%.
The common electrode 42 is set to a predetermined reference potential. The capacity Co is electrically connected to a capacitance line 36 whose one end is electrically connected to the pixel electrode 41 and the other end is kept at a constant voltage Vcom. In addition, the common electrode 42 is also held 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 their electrical connection states, namely, conduction and insulation. More specifically, the gate of the selection switch Sw, which is an n-channel transistor, is electrically connected to the scan line 32. When the scanning signal GS[i] is set to a selection potential, the selection switch Sw provided at the pixel circuit 40 of ith row is set to an on state. The image signal VD[j] is supplied from the data line 34 to the pixel circuit 40 where the selection switch Sw is set to an on state, and a voltage corresponding to the image signal VD[j] is applied to the liquid crystal element CL. In this manner, the transmittance of the liquid crystal element CL of the pixel circuit 40 is changed in accordance with the image signal VD[j], and the panel pixel Px corresponding to this pixel circuit 40 displays a gradation level corresponding to the image signal VD[j].
When the selection switch Sw is set to an off state after a voltage corresponding to the image signal VD[j] is applied to the liquid crystal element CL of the pixel circuit 40, the potential at the pixel electrode 41 is held by the capacity Co. Therefore, in a period until the selection switch Sw is set to an on state after the selection switch Sw is set to an on state, a voltage corresponding to the image signal VD[j] is continuously applied to the liquid crystal element CL. Here, when a DC voltage is applied to the liquid crystal element CL, its electrical characteristics are degraded and a so-called burn-in phenomenon is caused. In view of this, this embodiment employs an AC drive that reverses the potential of the image signal VD[j] relative to a predetermined potential. The predetermined potential is, for example, a common potential applied to the common electrode 42. A potential with the voltage drop of the transistor of the selection switch Sw taken into account may be employed as the predetermined potential. The case where the potential of the image signal VD[j] is higher than the predetermined potential is referred to as positive polarity (+), and the case where the potential of the image signal VD[n] is lower than the predetermined potential is referred to as negative polarity (−). For the reverse of the polarity, this embodiment employs a method in which the polarity of the image signal VD[j] applied to the pixel electrode 41 with respect to the predetermined potential is changed, with the predetermined potential fixed.
With reference to
The light path shifting element driving unit 14 drives the light path shifting element 110 on the basis of the control signal CLD supplied from the timing signal generation unit 12 and the control signal CLU supplied from the image processing unit 11. Accordingly, the control unit 50 controls the timing when the light path shifting element 110 shifts the projection pixel Pi, the direction in which the light path shifting element 110 shifts the projection pixel Pi, and the image signal VD[j] supplied to each of the plurality of the panel pixels Px.
The light path shifting element 110 illustrated in
Accordingly, as illustrated in
Each of the frame period N and the frame period N+1 is divided into four unit periods sf, namely, 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
Current frame period N
First unit period sf1−1
Second unit period sf2−1
Third unit period sf3−1
Fourth unit period sf4−1
Next frame period N+1
First unit period sf1−2
Second unit period sf2−2
Third unit period sf3−2
Fourth unit period sf4−2
As illustrated in
As illustrated in
In this embodiment, the shift direction of the light path shifting element 110 is two directions, namely, the first direction X and the second direction Y.
More specifically, as illustrated in
Next, upon transition from the first unit period sf1−1 to the second unit period sf2−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the second unit period sf2−1 to the third unit period sf3−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the second direction Y. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the third unit period sf3−1 to the fourth unit period sf4−1, the light path shifting element 110 shifts the projection pixel Pi by 0.5 pixel toward the other side X2 in the first direction X along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −. In this manner, the frame period N is terminated.
Next, as illustrated in
Next, upon transition from the first unit period sf1−2 to the second unit period sf2−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X.
At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the second unit period sf2−2 to the third unit period sf3−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the second direction Y. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the second unit period sf2−2 to the third unit period sf3−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the second direction Y. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +. In this manner, the frame period N+1 is terminated.
Next, upon transition 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 shifting element 110 shifts the projection pixel Pi toward the other side Y2 in the second direction Y by 0.5 pixel pitch along the direction parallel to the second direction Y. In transition from the frame period N+1 to the frame period N in this manner, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of all of the plurality of panel pixels Px between the frame period N and the frame period N+1. In this embodiment, in the first unit period sf1−2 in the frame period N+1, the polarity of the image signal VD is −, and therefore the control unit 50 sets the polarity of the image signal VD to + regardless of the shift direction of the projection pixel Pi upon transition 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. Thereafter, the frame period N and the frame period N+1 are alternately executed. As a result, in the projection image 100, the adjacent projection pixels Pi are driven with opposite polarities.
In this embodiment, the projection pixel Pi is shifted by the light path shifting element 110 in this manner, and thus the projection image 100 with a resolution higher than the panel resolution can be achieved. In addition, in the projection image 100, the adjacent projection pixels Pi are driven with opposite polarities, and thus the flicker or the like of the projection image 100 is less generated. Also in this case, all of the plurality of panel pixels Px are driven in the same polarity in a single unit period sf, and thus the load at the image processing unit 11 of the control unit 50 and the data line driving circuit 24 is small.
Also in this embodiment, as in the first exemplary operation, each of the current frame period N and the next frame period N+1 is divided into four unit periods sf, namely, the first unit period sf1, the second unit period sf2, the third unit period sf3, and the fourth unit period sf4, as illustrated in
Also in this embodiment, the light path shifting element 110 shifts the projection pixel Pi for each unit period sf in the frame period N illustrated in
In this embodiment, a plurality of shift directions of the light path shifting element 110 include, in addition to the first direction X, the third direction C that intersects both of the first direction X and the second direction Y, and the fourth direction D that obliquely intersects the first direction X and the second direction Y on the side opposite to the third direction C. Here, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px when the light path shifting element 110 shifts the projection pixel Pi along the direction parallel to the first direction X in the same frame period N, whereas the control unit 50 does not reverse the polarity of the image signal VD supplied to the pixel electrode 41 of each of all of the plurality of panel pixels Px when the light path shifting element 110 shifts the projection pixel Pi along at least one of the direction parallel to the third direction C and the direction parallel to the fourth direction D.
More specifically, in the first unit period sf1−1 in the frame period N illustrated in
Next, upon transition from the first unit period sf1−1 to the second unit period sf2−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the second unit period sf2−1 to the third unit period sf3−1, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD for all of the plurality of panel pixels Px, and therefore the polarity of the image signal VD is −.
Next, upon transition from the third unit period sf3−1 to the fourth unit period sf4−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +. In this manner, the frame period N is terminated.
Next, as illustrated in
Next, upon transition from the first unit period sf1−2 to the second unit period sf2−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the second unit period sf2−1 to the third unit period sf3−1, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is +.
Next, upon transition from the third unit period sf3−1 to the fourth unit period sf4−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −. In this manner, the frame period N+1 is terminated.
Next, upon transition 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 shifting element 110 shifts the projection pixel toward the other side X2 in the first direction X and the other side Y2 in the second direction Y Pi by 0.5 pixel pitch along the direction parallel to the fourth direction D. In this manner, upon transition from the next frame period N+1 to the frame period N, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px between the frame period N+1 and the frame period N. In this embodiment, in the first unit period sf1−2 of the frame period N+1, the polarity of the image signal VD is −, and therefore, upon transition 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 of the plurality of panel pixels Px to + regardless of the shift direction of the projection pixel Pi. Thereafter, the frame period N and the frame period N+1 are alternately executed. As a result, in the projection image 100, the adjacent projection pixels Pi are driven with opposite polarities.
In this embodiment, the projection pixel Pi is shifted by the light path shifting element 110 in this manner, and thus the projection image 100 with a resolution higher than the panel resolution can be achieved. In addition, in the projection image 100, the adjacent projection pixels Pi are driven with opposite polarities, and thus the flicker or the like of the projection image 100 is less generated. Also in this case, all of the plurality of panel pixels Px are driven in the same polarity in a single unit period sf, and thus the load at the image processing unit 11 of the control unit 50 and the data line driving circuit 24 is small.
As illustrated in
Current frame period N
First subframe period Na−1
First unit period sf1−1
Second unit period sf2−1
Third unit period sf3−1
Fourth unit period sf4−1
Second subframe period Nb−1
Fifth unit period sf5−1
Sixth unit period sf6−1
Seventh unit period sf7−1
Eighth unit period sf8−1
Next frame period N+1
First subframe period Na−2
First unit period sf1−2
Second unit period sf2−2
Third unit period sf3−2
Second subframe period Nb−2
Fourth unit period sf4−2
Fifth unit period sf5−2
Sixth unit period sf6−2
Seventh unit period sf7−2
Eighth unit period sf8−2
In this embodiment, as illustrated in
More specifically, in the first subframe period Na in the frame period N and the next frame period N+1, the panel pixel a1 of the liquid crystal panel 10 expresses the four projection pixels A1, A2, B1 and B2. On the other hand, in the second subframe period Nb in the frame period N and the next frame period N+1, the panel pixel a1 of the liquid crystal panel 10 expresses four projection pixels B2, B3, C2 and C3. As such, in the first subframe period Na and the second subframe period Nb, the projection pixel B2 is in common, but the other projection pixels Pi are different. That is, the region where the projection pixel Pi is shifted by the light path shifting element 110 is different between the first subframe period Na and the second subframe period Nb.
The same applies to other panel pixels Px. For example, in the first subframe period Na in the frame period N and the next frame period N+1, the panel pixel a2 of the liquid crystal panel 10 expresses four projection pixels A3, A4, B3 and B4. On the other hand, in the second subframe period Nb in the frame period N and the next frame period N+1, the panel pixel a2 of the liquid crystal panel 10 expresses four projection pixels B4, B5, C4 and C5. As such, in the first subframe period Na and the second subframe period Nb, the projection pixel B4 is in common, but the other projection pixels Pi are different.
In addition, in the first subframe period Na in the frame period N and the next frame period N+1, the panel pixel b1 of the liquid crystal panel 10 expresses four projection pixels C1, C2, D1 and D2. On the other hand, in the second subframe period Nb in the frame period N and the next frame period N+1, the panel pixel b1 of the liquid crystal panel 10 expresses four projection pixels D2, D3, E2 and E3. As such, in the first subframe period Na and the second subframe period Nb, the projection pixel D2 is in common, but the other projection pixels Pi are different.
In this embodiment, in the frame period N and the frame period N+1, the light path shifting element 110 shifts the projection pixel Pi by 0.5 pixel pitch for each unit period sf. At this time, the control unit 50 sets the same polarity to the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px in the same unit period sf in the plurality of unit periods sf, whereas the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px when the light path shifting element 110 shifts the projection image along at least one of the direction parallel to the first direction X and the direction parallel to the second direction Y upon transition from the current unit period sf to the next unit period sf in the same frame period N. In addition, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px between the current frame period N and the next frame period N+1.
In this embodiment, as in the second exemplary operation, a plurality of shift directions of the light path shifting element 110 include, in addition to the first direction X, the third direction C that intersects both of the first direction X and the second direction Y, and the fourth direction D that obliquely intersects the first direction X and the second direction Y on the side opposite to the third direction C. Here, when the light path shifting element 110 shifts the projection image along the direction parallel to the first direction X in the same frame period N, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px, whereas the control unit 50 does not reverse the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px when the light path shifting element 110 shifts the projection image along at least one of the direction parallel to the third direction C and the direction parallel to the fourth direction D.
More specifically, in the first subframe period Na−1 of the frame period N illustrated in
Next, upon transition from the first unit period sf1−1 to the second unit period sf2−1 in the first subframe period Na−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the second unit period sf2−1 to the third unit period sf3−1 in the first subframe period Na−1, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is −.
Next, upon transition from the third unit period sf3−1 to the fourth unit period sf4−1 in the first subframe period Na−1, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the fourth unit period sf4−1 of the first subframe period Na−1 to the fifth unit period sf5−1 of the second subframe period Nb−1 in the frame period N, the light path shifting element 110 shifts the projection pixel Pi toward one side X1 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the fourth direction D. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is +.
Next, upon transition from the fifth unit period sf5−1 to the sixth unit period sf6−1 in the second subframe period Nb−1, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the sixth unit period sf6−1 to the seventh unit period sf7−1 in the second subframe period Nb−1, the light path shifting element 110 shifts the projection pixel Pi toward one side X1 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is −.
Next, upon transition from the seventh unit period sf7−1 to the eighth unit period sf8−1 in the second subframe period Nb−1, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +. In this manner, the frame period N is terminated.
Next, as illustrated in
Next, upon transition from the first unit period sf1−2 to the second unit period sf2−2 in the first subframe period Na−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the second unit period sf2−2 to the third unit period sf3−2 in the first subframe period Na−2, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is +.
Next, upon transition from the third unit period sf3−2 to the fourth unit period sf4−2 in the first subframe period Na−2, the light path shifting element 110 shifts the projection pixel Pi toward the one side X1 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −.
Next, upon transition from the fourth unit period sf4−2 of the first subframe period Na−2 to the fifth unit period sf5−2 of the second subframe period Nb−2 in the frame period N+1, the light path shifting element 110 shifts the projection pixel Pi toward one side X1 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the fourth direction D. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is −.
Next, upon transition from the fifth unit period sf5−2 to the sixth unit period sf6−2 in the second subframe period Nb−2, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from − to +.
Next, upon transition from the sixth unit period sf6−2 to the seventh unit period sf7−2 in the second subframe period Nb−2, the light path shifting element 110 shifts the projection pixel Pi toward one side X1 in the first direction X and the one side Y1 in the second direction Y by 0.5 pixel pitch along the direction parallel to the third direction C. At this time, the control unit 50 does not reverse the polarity of the image signal VD, and therefore the polarity of the image signal VD for all of the plurality of panel pixels Px is +.
Next, upon transition from the seventh unit period sf7−2 to the eighth unit period sf8−2 in the second subframe period Nb−2, the light path shifting element 110 shifts the projection pixel Pi toward the other side X2 in the first direction X by 0.5 pixel pitch along the direction parallel to the first direction X. At this time, the control unit 50 reverses the polarity of the image signal VD for all of the plurality of panel pixels Px from + to −. In this manner, the frame period N+1 is terminated.
Next, upon transition 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 shifting element 110 shifts the projection pixel toward the other side X2 in the first direction X and the other side Y2 in the second direction Y Pi by 0.5 pixel pitch along the direction parallel to the fourth direction D. In transition from the next frame period N+1 to the current frame period N in this manner, the control unit 50 reverses the polarity of the image signal VD supplied to the pixel electrode 41 of each of the plurality of the panel pixels Px between the current frame period N and the next frame period N+1. In this embodiment, in the first unit period sf1−2 in the frame period N+1 illustrated in
In this embodiment, the projection pixel Pi is shifted by the light path shifting element 110 in this manner, and thus the projection image 100 with a resolution higher than the panel resolution can be achieved. In addition, in the projection image 100, the adjacent projection pixels Pi are driven with opposite polarities, and thus the flicker or the like of the projection image 100 is less generated. Also in this case, all of the plurality of panel pixels Px are driven in the same polarity in a single unit period sf, and thus the load at the image processing unit 11 of the control unit 50 and the data line driving circuit 24 is small.
In addition, as described below with reference to
As a result, in the first exemplary operation illustrated in
Conversely, in the third exemplary operation illustrated in
It should be noted that in this embodiment, to express the projection pixels C1, C2, in the second subframe period Nb−1, the panel pixels a1, a2, are set to the black display, with the other panel pixels Px set to the white display. As a result, the black shadow PE0 due to alignment defects appears between the projection pixels C1, C2, . . . at the third row and the projection pixels E1, E2, at the fifth row in the first unit period sf1−1 and the second unit period sf2−1 of the second subframe period Nb−1, but the black shadow PE0 is not noticeable since the black shadow PE0 is contiguous with the projection pixels C1, C2, of the black display.
In addition, in the third unit period sf3−1 of the second subframe period Nb−1, the projection pixels C1, C2, of the black display are not expressed, and therefore the residual portion PE1 of the black shadow is generated in the white background, and, also in the fourth unit period sf4 of the frame period N, the residual portion PE2 of the black shadow slightly remains.
Even in this case, the location where alignment defect remains in the liquid crystal panel 10 is between the panel pixels a1, a2, and the panel pixels b1, b2, As such, the locations where the residual portions PE1 and PE2 of the black shadow appear differ between the first subframe period Na−1 and the second subframe period Nb−1, and thus the presence of the residual portions PE1 and PE2 of the black shadow is less likely to be noticeable.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-088219 | May 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20150219983 | Mashitani | Aug 2015 | A1 |
| 20200098295 | Hosaka | Mar 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 2020-052132 | Apr 2020 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20220383785 A1 | Dec 2022 | US |
