Projection type video display device

Abstract

To provide a projection type video display device with which it is possible to obtain a high-resolution video, and which reduces necessary electric power and suppresses heat generation.SOLUTION: The projection type video display device comprises: a video generation unit for generating video light on the basis of a video input signal; a projection optical system for projecting video light to a projection plane; an optical path change unit disposed on the optical path of video light and having an actuator that shifts the display position of video light on the projection plane in two different directions; and a control unit for controlling the video generation unit and the optical path change unit on the basis of the video input signal. The frequency component of shift amount waveform in each direction of pixel at a display position on the projection plane of video light driven by the actuator of the optical path change unit respectively has a fundamental frequency component of sine wave and an odd-number harmonics, and the minimum value of shift amount of the pixel at the display position on the projection plane of video light is 0.8 times the maximum value of shift amount or greater.SELECTED DRAWING: Figure 15A

Description

Technical Field

[0001] The present disclosure relates to a projection-type video display device capable of projecting a video while shifting an optical path of video light at a predetermined period.

Background Art

[0002] Conventionally, in order to obtain a high-resolution and high-quality video, a projection-type video display device is known in which a so-called optical path changing unit that controls the optical path of video light generated by a video generation unit such as a liquid crystal panel and changes the position where the video is displayed on the projection surface is inserted. By using this optical path changing unit, the projection-type video display device can provide a high-resolution video even when a video input signal having a resolution higher than that of the video generation unit is input (for example, Patent Document 1).

[0003] Patent Document 2 discloses an optical device capable of reducing deterioration of an image due to a drive signal, and an image display device including such an optical device. In this device, the waveform of the drive locus of the optical path changing unit is a trapezoidal wave whose frequency components are composed of the fundamental frequency of a sine wave and odd-order harmonics, and the image quality is improved by increasing the time ratio of the flat part of the trapezoidal wave.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the optical path changing unit operates corresponding to the frequency of the video signal, for example, in the case of a 60 Hz video signal, it is necessary to perform a high-speed repetitive motion of 60 cycles per second. Here, the optical path changing unit often has to be arranged in a high-temperature and limited space, such as between a projection prism and a projection lens. The optical path changing unit may include an actuator using a magnet, and magnets have the characteristic of thermal demagnetization in which their performance deteriorates in a high-temperature environment depending on the type. When such a magnet is used, if the temperature rises due to heat generation from energy loss in the actuator, etc., the thrust of the actuator will decrease.

[0006] Particularly in the case of a DLP type projector, since heat generation due to heat generation at the off-light heat shield and light loss in the projection optical system is large, the surrounding temperature is high. To be used in a temperature range where the magnet does not thermally demagnetize, it is necessary to efficiently drive the actuator to suppress heat generation. Usually, if the magnet is made larger, it can be driven with less power and heat generation, but as described above, there is a limit because the space is limited.

[0007] An object of the present disclosure is to provide a projection type video display device that can obtain a high-resolution video by pixel shift, reduce the power required for the actuator of the optical path changing unit, and suppress heat generation in the optical path changing unit.

Means for Solving the Problems

[0008] The projection-type video display device according to the present disclosure includes a video generation unit that generates video light based on a video input signal, a projection optical system that projects the video light onto a projection surface, an optical path changing unit that is provided on the optical path of the video light and has an actuator that shifts the display position of the video light on the projection surface in two different directions, and a control unit that controls the video generation unit and the optical path changing unit based on the video input signal. The frequency components of the waveforms of the amounts of shift in each direction of the pixels at the display position on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and odd harmonic components, and the minimum value of the amount of shift of the pixels at the display position on the projection surface of the video light is 0.8 times or more the maximum value of the amount of shift.

[0009] Also, the projection-type video display device according to the present disclosure includes a video generation unit that generates video light based on a video input signal, a projection optical system that projects the video light onto a projection surface, an optical path changing unit that is provided on the optical path of the video light and has an actuator that shifts the display position of the video light on the projection surface in two different directions, and a control unit that controls the video generation unit and the optical path changing unit based on the video input signal. The frequency components of the waveforms of the amounts of shift in each direction of the pixels at the display position on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and odd harmonic components. The waveforms of the amounts of shift in each direction have two or more and four or less inflection points within a half cycle, and one peak having an absolute value larger than that of the inflection points between two inflection points.

Advantages of the Invention

[0010] The present disclosure can provide a projection-type video display device that can obtain a high-resolution video by pixel shifting, reduce the power required for the actuator of the optical path changing unit, and suppress heat generation in the optical path changing unit.

Brief Description of the Drawings

[0011]

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Figure 15A

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Figure 15C

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Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described in detail with appropriate reference to the drawings. However, overly detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art.

[0013] The inventor provides the accompanying drawings and the following description for those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the claims by these.

[0014] Also, note that the drawings are schematic and the ratios of dimensions etc. are different from the actual ones. Therefore, specific dimensions etc. should be determined with reference to the following description. Also, of course, there are parts where the relationships and ratios of the dimensions between the drawings are different from each other.

[0015] (Embodiment 1) [1-1. Configuration of Projection-Type Video Display Device] First, the configuration of the projection-type video display device 100 according to Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 and 2. FIG. 1 is an external perspective view of the projection-type video display device 100. FIG. 2 is a block diagram showing the configuration of the projection-type video display device 100. As shown in FIG. 1, the projection-type video display device 100 projects video light generated according to a video input signal onto a screen 1 as a projection surface. The projection surface is not limited to a two-dimensional plane such as the screen 1, but may also be the surface of a three-dimensional solid such as a building.

[0016] The projection-type video display device 100 includes a light source unit 10 that irradiates light, a video generation unit 20 that generates video light according to a video input signal, a light guide optical system 50 that guides the light from the light source unit 10 to the video generation unit 20, a projection optical system 60 that projects the generated video light onto the screen 1, and a control unit 70 that controls the light source unit 10, the video generation unit 20, etc.

[0017] Although details will be described later, the projection-type video display device 100 further includes an optical path changing unit 102 for shifting the display position of the video light generated by the video generation unit 20 within a range equal to or less than the pixel pitch on the screen 1. The projection-type video display device 100 can provide a video with a high sense of resolution by shifting the display position of the video light generated by the video generation unit 20 on the screen 1 by, for example, 1 / 2 pixel in each of the vertical and horizontal directions by the optical path changing unit 102.

[0018] [1-2. Optical Configuration of Projection-Type Video Display Device] The optical configuration of the projection-type image display device 100 will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing the optical configuration of the projection-type image display device 100.

[0019] The light guide optical system 50 includes a lens 52, a rod integrator 54, a lens 56, and a mirror 58. The white light emitted from the light source unit 10 enters the lens 52 and is condensed near the incident surface of the rod integrator 54. The light incident on the rod integrator 54 is reflected multiple times inside the rod integrator 54, and the light intensity distribution is substantially equalized and then exits. The light exiting from the rod integrator 54 is condensed by the lens 56. The lens 56 is a relay lens that forms an image of the exit surface of the rod integrator 54 on a DMD, which will be described later. After being reflected by the mirror 58, it enters the total reflection prism 24 through the lens 22. The lens 22 is a lens that condenses the incident light in a substantially parallel manner.

[0020] The video generation unit 20 includes a lens 22, a total reflection prism 24, a color prism 28, and DMDs 34, 36, and 38.

[0021] The total reflection prism 24 is composed of two prisms, and a thin air layer 26 is interposed between the adjacent surfaces of the prisms. The air layer 26 totally reflects the light incident at an angle equal to or greater than the critical angle. The light incident on the total reflection prism 24 through the lens 22 is reflected by the total reflection surface in contact with the air layer 26 and enters the color prism 28.

[0022] The color prism 28 has three prisms, and a dichroic film 30 for reflecting blue light and a dichroic film 32 for reflecting red light are formed on the adjacent surfaces of the respective prisms. The light incident on the color prism 28 is separated into blue, red, and green color lights by the dichroic film 30 for reflecting blue light and the dichroic film 32 for reflecting red light, and enters the DMDs 34, 36, and 38, respectively. The DMDs 34, 36, and 38 deflect the micromirrors to separate the light incident on the projection lens constituting the projection optical system 60 and the light traveling outside the effective range of the projection lens according to the video input signal.

[0023] Each color light reflected by DMDs 34, 36, and 38 passes through the color prism 28 again. In the process of passing through the color prism 28, the separated blue, red, and green color lights are synthesized and enter the total reflection prism 24. Since the light incident on the total reflection prism 24 enters at an angle less than the critical angle with respect to the air layer 26, it passes through and enters the projection optical system 60. In this way, the image light formed by DMDs 34, 36, and 38 is projected onto the screen 1.

[0024] Since the image generation unit 20 includes DMDs 34, 36, and 38, a projection type image display device 100 with high light resistance and heat resistance can be realized compared to a liquid crystal panel. Furthermore, since three DMDs 34, 36, and 38 are used, good color reproduction can be achieved, and a bright and high-definition projection image can be obtained.

[0025] [1-3. Configuration of the optical path changing unit] An example of the configuration of the optical path changing unit 102 of the present embodiment will be described with reference to FIG. 4. FIG. 4 is a schematic diagram showing the optical configuration from the image generation unit 20 to the projection optical system 60.

[0026] The optical path changing unit 102 includes a parallel flat glass 104 and a voice coil actuator 106 that rotates the parallel flat glass 104 in two directions orthogonal to the optical axis of the projection optical system 60. The voice coil actuator 106 has an inexpensive configuration using a magnet and a coil, and can be driven repeatedly at high speed, so it is suitable as an actuator for the optical path changing unit. Also, for the magnet, a neodymium magnet or the like that is small and easy to obtain thrust may be adopted.

[0027] In the voice coil actuator 106, an adhesive is used for the purpose of fixing the magnet, preventing disconnection due to the vibration of the coil wire, and preventing loosening of the screw. If the adhesive is used beyond the heat resistance range, not only will the device malfunction due to a decrease in the adhesive performance, but outgassing will occur, which will be guided onto the optical path due to the light collection effect, and finally adsorbed on the surface of the optical component, resulting in a decrease in the light transmittance and thus a decrease in the brightness of the image display device. In addition, the heat absorbed by the optical component increases, causing cracks in the optical component and preventing correct screen display in some cases. That is, from this point as well, it is necessary to efficiently drive the voice coil actuator 106 to suppress heat generation.

[0028] An actuator drive unit 72 that supplies power to the voice coil actuator 106 and controls the rotation operation of the parallel plate glass 104 is connected to the voice coil actuator 106. The parallel plate glass 104 is disposed on the optical path between the projection optical system 60 and the total reflection prism 24.

[0029] FIG. 5 is a diagram for explaining an example of the optical path changing unit 102. The optical path changing unit 102 includes a mount frame 108, a glass outer frame 110, a glass inner frame 112, and a coil fixing frame 114.

[0030] The mount frame 108 and the glass outer frame 110 are connected by screws via an outer frame spring 116. The glass outer frame 110 and the glass inner frame 112 are connected by screws via an inner frame spring 118. The parallel plate glass 104 is fixed to the glass inner frame 112 by a leaf spring 120. The mount frame 108 and the coil fixing frame 114 are fixed by screws.

[0031] FIG. 6A and FIG. 6B show a part of the optical path changing unit 102. As shown in FIG. 6A, a yoke 122 and a magnet 124 are fixed to the glass outer frame 110 with screws and adhesives. Also, a yoke 126 and a magnet 128 are fixed to the glass inner frame 112 with screws and adhesives. Here, the arrow 130 indicates the direction of the magnetic field of the magnet. As shown in FIG. 6B, coils 132 and 134 are fixed to the coil fixing frame 114 with an adhesive. Also, the actuator driving unit 72 is fixed with a screw. The arrow 136 indicates the winding direction of the coil.

[0032] When the coil 132 receives current from the actuator driving unit 72, a Lorentz force is generated between the magnet 124 and the coil 132, and between the magnet 128 and the coil 134. Here, since the coils 132 and 134 are fixed in position by the coil fixing frame 114 respectively, a thrust force is generated on the side of the magnets 124 and 128. When a positive current is passed through the coil 132 of the glass outer frame 110, the thrust of the magnet 124 is transmitted through the glass outer frame 110, the outer frame spring is elastically deformed, and the parallel plate glass 104 rotates in the direction of the arrow 140 in FIG. 5. When a positive current is passed through the coil 134 of the glass inner frame 112, the thrust of the magnet 128 is transmitted through the glass inner frame 112, the inner frame spring 118 is elastically deformed, and the parallel plate glass 104 rotates in the direction of the arrow 142.

[0033] FIG. 7 is a diagram for explaining the principle of optical path change by the parallel plate glass 104. As shown in FIG. 7, when the plane of the parallel plate glass 104 is orthogonal to the input light ray 144, the input light ray 144 travels straight without refraction at the interface between the parallel plate glass 104 and air. Also, when the input light ray 144 passes through the parallel plate glass 104 and exits into the air, since the parallel plate glass 104 is a parallel plane and the light ray is orthogonal to the interface, the light ray travels straight without refraction. Therefore, when the input light ray 144 is image light, no movement of the image occurs.

[0034] On the other hand, when the parallel flat glass 104 is not orthogonal to the input light beam 144 as shown by the dashed line in FIG. 7, the input light beam 144 is refracted at the interface between the parallel flat glass 104 and air. After the input light beam 144 is refracted and enters the parallel flat glass 104, it passes through the parallel flat glass 104 and is refracted at the interface where it exits into the air because the light beam is not orthogonal to the interface.

[0035] Since the parallel flat glass 104 has parallel planes, the angle of refraction when entering the parallel flat glass 104 is equal to the angle of refraction when exiting the parallel flat glass 104. For this reason, if the input light beam 144 is video light, the video light of the output light beam 146 is translated in parallel in the tilt direction of the parallel flat glass 104. As a result, the display position of the video projected and output from the parallel flat glass 104 will move. In the present embodiment, the parallel flat glass 104 can be rotated independently in two directions, respectively, in the positive and negative directions. For example, in FIG. 5, the parallel flat glass 104 is independently rotated in the direction of arrow 140 and the reverse direction, and in the direction of arrow 142 and the reverse direction, so it is possible to perform control to shift the display position independently in two directions.

[0036] (Operation of the control unit) The control by the control unit 70 will be described with reference to FIGS. 8 to 11. FIG. 8 is a block diagram for explaining the configuration of the control unit 70. The control unit 70 includes a video signal generation unit 74, a display element drive unit 76, and an actuator drive unit 72.

[0037] The video input signal input to the control unit 70 is converted in the video signal generation unit 74 into video output signals respectively output to the DMDs 34, 36, 38 and into a synchronization signal for synchronizing with the video light generated by the DMDs 34, 36, 38. That is, the video signal generation unit 74 generates a video output signal and a synchronization signal based on the video input signal.

[0038] When a video input signal with the same resolution as DMD34, 36, and 38 is input, the video signal generation unit 74 outputs the video input signal corresponding to each pixel of DMD34, 36, and 38 as it is to the display element driving unit 76 as a video output signal. Based on the correspondence relationship (address) between the video output signal and each pixel, the display element driving unit 76 outputs the video output signal to each pixel of DMD34, 36, and 38.

[0039] When a video input signal with a resolution four times that of DMD34, 36, and 38 is input, the video signal generation unit 74 usually calculates a signal for interpolated pixels (the average value of four pixels) from four signals of 2×2, and outputs it as a video output signal to each pixel of DMD34, 36, and 38. Alternatively, as shown in FIG. 9, the video signal generation unit 74 samples, for example, the upper left signal (the signal marked with ○) among the four signals of 2×2 as a video output signal, and outputs it to the display element driving unit 76.

[0040] FIGS. 10 and 11 are schematic diagrams for explaining the signal processing flow when driving the optical path changing unit 102 to display a video with a resolution four times denser than that of DMD34, 36, and 38. As shown in FIG. 10, the video signal generation unit 74 temporally divides the video input signal for one frame into four sub-frames.

[0041] Specifically, among the four 2×2 signals, the upper left signal (for example, the video input signal (00)) is used as the first sub-frame, the upper right signal (for example, the video input signal (10)) is used as the second sub-frame, the lower right signal (for example, the video input signal (11)) is used as the third sub-frame, and the lower left signal (for example, the video input signal (01)) is used as the video output signal of the fourth sub-frame, and is output to the display element driving unit 76 in this order during one frame. On the other hand, to the actuator driving unit 72, a synchronization signal is output so that the timing when each sub-frame switches and the timing when the optical path changing unit 102 shifts the display position on the screen (changes the optical path of the video light) coincide.

[0042] Based on the synchronization signal, by shifting the display position on the screen, as shown in FIG. 11, while the optical path changing unit 102 is displaying the video of the first sub-frame on the DMDs 34, 36, and 38, the optical path changing unit 102 projects the video light to a predetermined position (reference position) on the screen, here the upper left (UL) position as viewed from the projection type video display device 100.

[0043] Next, while the DMDs 34, 36, and 38 are displaying the video of the second sub-frame, the optical path changing unit 102 changes the optical path so as to project the video light to the position indicated by the solid line that has moved 1 / 2 pixel to the left from the reference position indicated by the dotted line (here the upper right (UR) position).

[0044] While the DMDs 34, 36, and 38 are displaying the video of the third sub-frame, the optical path changing unit 102 further moves 1 / 2 pixel downward and changes the optical path so as to project the video light to the position indicated by the solid line that has moved 1 / 2 pixel vertically and horizontally from the reference position (here the lower right (DR) position).

[0045] Finally, while the DMDs 34, 36, and 38 are displaying the video of the fourth sub-frame, the optical path changing unit 102 moves 1 / 2 pixel to the right and changes the optical path so as to project the video light to the position indicated by the solid line that has moved 1 / 2 pixel downward from the reference position (here the lower left (DL) position).

[0046] However, as described in the embodiments below, in actuality, for the optical path change, in order to avoid the overall video brightness from decreasing as usual during the transition time, sub-frame display is often performed while moving without turning off the normal projection light at the time of switching. That is, the higher the time that the traveling path stays at the position of 1 / 2 pixel for each sub-frame, the higher the quality video can be delivered.

[0047] (Operation of the optical path changing unit) Hereinafter, the details of the embodiments regarding the operation of the optical path changing unit 102 according to the present disclosure will be described.

[0048] FIG. 12 shows an example of the relationship between the time transition of the pixel shift amount in each of the two directions and the video output signal by the optical path changing unit 102 in Embodiment 1. The vertical axis represents the magnitude of the shift amount when the magnitude of the pixel pitch at the display position is set to 1, and the horizontal axis represents time, where T represents one cycle. As described in the present disclosure, the frequency components of the waveforms Ay(t) and Ax(t) of the pixel shift amounts in each direction at the display position include the fundamental frequency component of the sine wave and the odd harmonic components, and the pixel shift amount at the display position on the projection surface of the video light is set to 80% or more of its maximum value.

[0049] Specifically, when the fundamental frequency is f, one waveform Ay(t) is Ay(t)=α1×{β1×sin(2πf)+β2×sin(2π·3f)+ β3×sin(2π·5f)}···Equation (1) Here, for example, the coefficient α1 = 0.35, the coefficient β1 = 1, and the coefficients β2 = β3 = 0.101. Note that the respective values of the coefficients β1 to β3 may be different. Here, the coefficients β2 and β3 are set to be 0.101 times or more, for example, 5% or more of the coefficient β1. Thereby, in the waveform Ay(t), the odd harmonic component has a component of 5% or more with respect to the fundamental frequency component. The fundamental frequency f is, for example, 60 Hz.

[0050] The other waveform Ax(t) is set to a waveform with a 90-degree phase shift from Ay(t). That is, Ax(t)=α1×{β1×sin(2πf+π / 2)+β2×sin(2π·3f+π / 2)+ β3×sin(2π·5f+π / 2)}···Equation (2)

[0051] The waveform Ay(t) of the shift amount has two inflection points Pf within a half cycle of 0 to 1 / 2 cycle, and one peak Pk with an absolute value larger than that of the inflection point Pf between the two inflection points Pf. It also has two inflection points Pf within a half cycle of 1 / 2 to 1 cycle, and one peak Pk with an absolute value larger than that of the inflection point Pf between the two inflection points Pf. Similarly, the waveform Ax(t) of the shift amount has two inflection points Pf within a half cycle of 1 / 44 to 3 / 4 cycle, and one peak Pk with an absolute value larger than that of the inflection point Pf between the two inflection points Pf. It also has two inflection points Pf within a half cycle of 3 / 4 to 1 / 4 cycle, and one peak Pk with an absolute value larger than that of the inflection point Pf between the two inflection points Pf.

[0052] Figure 13A represents the locus of the pixel center of the display position on the projection surface of the video light in a rectangular coordinate system. Figure 13B shows the result plotted every 1 / 72 cycle. Figures 14A and 14B show the relationships between the distance and the declination angle and time when Figure 13A is converted into a polar coordinate system.

[0053] The minimum value rmin of the shift amount of the pixels at the display position on the projection surface of the video light may be, for example, 0.8 times or more of its maximum value rmax, and may also be between 0.8 times and 0.95 times, or between 0.90 times and 0.93 times. In the example shown in Figure 14A, the minimum value rmin of the shift amount of the pixels at the display position on the projection surface of the video light is 97.8% or more of its maximum value rmax, that is, it is almost a constant value.

[0054] From Figures 13B and 14B, at the positions where the first to fourth sub-frames indicated by the arrows are to be displayed, the display position has a decelerating motion, and since the first to fourth sub-frames are made easier to see, it is a waveform that can obtain a high-quality video. The positions where the first to fourth sub-frames are to be displayed are, for example, near the shift positions of the pixels at 1 / 8 cycle, 3 / 8 cycle, 5 / 8 cycle, and 7 / 8 cycle of the fundamental frequency.

[0055] FIG. 15A shows the case of Ay(t), FIG. 15B shows the case where only the frequency component of the third harmonic of Ay(t) is increased, and FIG. 15C shows the case where only the frequency component of the third harmonic of Ay(t) is further increased. Specifically, By(t)=0.35×{sin(2πf)+0.185×sin(2π·3f) +0.101×sin(2π·5f)}···Equation (3) Cy(t)=0.35×{sin(2πf)+0.27×sin(2π·3f) +0.101×sin(2π·5f)}···Equation (4) is set.

[0056] FIG. 15A(a), FIG. 15B(a), and FIG. 15C(a) show the time transition of the shift amount of each pixel. FIG. 15A(b), FIG. 15B(b), and FIG. 15C(b) show the trajectories of the pixel centers of the display positions on the projection surface of the video light. FIG. 15A(c), FIG. 15B(c), and FIG. 15C(c) show the time transition of the distance when the trajectories of the pixel centers are subjected to polar coordinate conversion. Here, generally, the larger the component of the waveform for each frequency, the larger the required power. That is, the required power has the relationship of Ay(t) < By(t) < Cy(t).

[0057] As shown in FIG. 15A(b), FIG. 15B(b), and FIG. 15C(b), when the frequency component of the third harmonic becomes smaller, the trajectory of the pixel center of the display position on the projection surface of the video light becomes closer to a circular orbit. This circular orbit passes through the positions where the first to fourth sub-frames want to perform display, and the display position moves with deceleration. As shown in FIG. 15A(c), FIG. 15B(c), and FIG. 15C(c), the shift amount of the pixels at the display positions on the projection surface of the video light is 97.8% or more of its maximum value in the case of Ay(t), and 84.3% or more of its maximum value in the case of By(t), satisfying the requirements proposed in the present disclosure. On the other hand, in the case of Cy(t), the minimum value of the pixel shift amount is 70.9% of its maximum value, and since it also includes orbits from 70.9% to 80% of the maximum value, it does not satisfy the requirements proposed in the present disclosure.

[0058] That is, in the waveform where the pixel shift amount on the projection surface of the projected image light proposed in the present disclosure is 80% or more of its maximum value, as in Ay(t) in FIG. 15A(b) and By(t) in FIG. 15B(b), compared with the conventional trapezoidal wave of Cy(t) in FIG. 15C(b), while the required third-harmonic frequency component is small, the first to fourth sub-frames pass through the position where display is desired, and the display position moves with a decelerating motion.

[0059] That is, in the present disclosure, in a projection-type image display device capable of projecting an image while shifting the optical path of the projected image light at a predetermined period, it is a driving method that can obtain a high-quality image while suppressing the power consumption and heat generation of the optical path changing unit 102.

[0060] In the present embodiment, the measurement of the waveform of the shift amount in each direction of the pixel is performed by reflecting laser light on a parallel flat glass 104 with a mirror attached thereto and detecting the angle change of the laser with a laser autocollimator. The detected angle change is detected as a waveform with an oscilloscope and can be separated into a fundamental frequency component, a third-harmonic frequency component, and a fifth-harmonic frequency component by Fourier transform. Examples of the laser autocollimator include the H900 series HRAD of Suruga Seiki Co., Ltd.

[0061] [1-2. Effects, etc.] The projection-type image display device 100 according to Embodiment 1 includes an image generation unit 20 that generates image light based on an image input signal, a projection optical system 60 that projects the image light onto a screen 1, an optical path changing unit 102 provided on the optical path of the image light and having a voice coil actuator 106 that shifts the display position of the image light on the screen 1 in two different directions, and a control unit 70 that controls the image generation unit 20 and the optical path changing unit 102 based on the image input signal. The frequency components of the waveform of the shift amount in each direction of the pixel of the display position of the image light on the screen 1 driven by the voice coil actuator 106 of the optical path changing unit 102 each have a fundamental frequency component of a sine wave and an odd harmonic component, and the minimum value of the shift amount of the pixel of the display position of the image light on the screen 1 is 0.8 times or more of the maximum value of the shift amount.

[0062] Since the waveform of the pixel shift amount has a fundamental frequency component of a sine wave and odd harmonic components, the displacement speed at the position where the sub-frame is to be displayed in the locus of the shift amount can be reduced compared to the uniform circular motion of the circular orbit by the sine wave, making it easier for a person watching the video to recognize the sub-frame and realizing an improvement in image quality. Also, since the minimum value of the pixel shift amount at the display position of the video light on Screen 1 is 0.8 times or more the maximum value of the shift amount, there are fewer odd harmonic components than in the case of driving by a conventional trapezoidal wave, and the power consumption of the voice coil actuator 106 can be reduced. Further, since the power consumption of the voice coil actuator 106 can be reduced, the amount of heat generation and noise from the optical path changing unit 102 can also be reduced.

[0063] In other words, in the projection type video display device 100 of Embodiment 1, the frequency components of the waveforms of the shift amounts in each direction of the pixels at the display position on Screen 1 of the video light driven by the voice coil actuator 106 of the optical path changing unit 102 each have a fundamental frequency component of a sine wave and odd harmonic components. The waveform of the shift amount in each direction has, within a half cycle, two or more and four or less inflection points Pf, and one peak having an absolute value larger than that of the inflection point Pf between two inflection points Pf.

[0064] Since there are four or less inflection points existing within a half cycle of the waveform, there are fewer odd harmonic components than in the case of driving by a conventional trapezoidal wave, and the power consumption of the voice coil actuator 106 can be reduced. Further, since the power consumption of the voice coil actuator 106 can be reduced, the amount of heat generation and noise from the optical path changing unit 102 can also be reduced.

[0065] Also, the waveform of the shift amount in each direction has three maximum values within one half cycle, the central maximum value among the three maximum values has the largest absolute value, and has three minimum values within the other half cycle, and the central minimum value among the three minimum values has the largest absolute value.

[0066] In addition, since the heat generation amount of the voice coil actuator 106 can be reduced, it is possible to suppress the occurrence of heat demagnetization characteristics in the magnet inside the voice coil actuator 106, and the voice coil actuator 106 can be continuously driven without increasing the size of the magnet. As a result, the increase in the size of the projection type video display device 100 can be suppressed.

[0067] (Embodiment 2) Next, Embodiment 2 will be described. The configuration of Embodiment 2 is common to the configuration of Embodiment 1 except for the points described below.

[0068] In Embodiment 2, specifically, when the fundamental frequency is f, one waveform Ay(t) is Dy(t)=0.34×{sin(2πf)+0.2×sin(2π·3f) +0.2×sin(2π·5f)} ··· Equation (5) set by.

[0069] The other waveform Dx(t) is set to a waveform with a 90-degree phase shift from Dy(t). That is, Dx(t)=0.34×{sin(2πf + π / 2)+0.2×sin(2π·3f + π / 2) +0.2×sin(2π·5f + π / 2)} ··· Equation (6) FIG. 16 shows the relationship between the time transition in each of the two directions of the pixel shift amount of the display position by the optical path changing unit 102 and the video output signal at that time.

[0070] The waveform Dy(t) of the shift amount has four inflection points Pf within a half period from 0 to 1 / 2 period, and one peak Pk with an absolute value larger than that of the inflection point Pf between two inflection points Pf. It also has four inflection points Pf within a half period from 1 / 2 to 1 period, and one peak Pk with an absolute value larger than that of the inflection point Pf between two inflection points Pf. Further, the waveform Dy(t) of the shift amount has three maximum values within a half period from 0 to 1 / 2 period, and the central maximum value among the three maximum values has the largest absolute value. It has three minimum values within a half period from 1 / 2 to 1 period, and the central minimum value among the three minimum values has the largest absolute value.

[0071] Similarly, the waveform Dx(t) of the shift amount has four inflection points Pf within a half period from 1 / 4 to 3 / 4 period, and one peak Pk with an absolute value larger than that of the inflection point Pf between two inflection points Pf. It also has four inflection points Pf within a half period from 3 / 4 to 1 / 4 period, and one peak Pk with an absolute value larger than that of the inflection point Pf between two inflection points Pf. Further, the waveform Dx(t) of the shift amount has three maximum values within a half period from 3 / 4 to 1 / 4 period, and the central maximum value among the three maximum values has the largest absolute value. It has three minimum values within a half period from 1 / 4 to 3 / 4 period, and the central minimum value among the three minimum values has the largest absolute value.

[0072] FIG. 17A shows the locus of the pixel centers of the display positions on the projection plane of the video light at that time in a rectangular coordinate system. FIG. 17B shows the result of plotting it every 1 / 72 cycle. FIGS. 18A and 18B show the relationships between the distance and the declination angle and time when FIG. 17A is converted into a polar coordinate system. As shown in FIG. 18A, the minimum value rmin of the pixel shift amount of the display position on the projection plane of the video light is 92.8% or more of its maximum value rmax. In the locus of the display positions in FIGS. 17B and 18B, there is a retrograde path around the positions where the first to fourth sub-frames are to be displayed, and around the positions where the first to fourth sub-frames are to be displayed, the display position swings and then stops. Usually, since this swinging motion is faster than the speed that can be perceived by the human eye, humans can visually recognize it as being displayed at a spatially averaged position. That is, it is also a waveform capable of obtaining a high-quality video in Dy(t).

[0073] In the waveform Dy(t) as well, compared with the case of generating a conventional trapezoidal wave, the required third-harmonic frequency component becomes smaller, so a high-resolution video can be obtained with less power and heat generation.

[0074] Also, since the locus of the display position on the projection plane of the video light has a retrograde path, the display position can swing and then stop, and a high-quality video can be obtained.

[0075] As described above, as an example of the technology in the present disclosure, embodiments have been described. For that purpose, the accompanying drawings and detailed descriptions have been provided. Therefore, among the components described in the accompanying drawings and detailed descriptions, there may be not only the components essential for solving the problems, but also the components not essential for solving the problems for the purpose of exemplifying the above technology. Therefore, just because those non-essential components are described in the accompanying drawings or detailed descriptions, it should not be immediately determined that those non-essential components are essential.

[0076] In addition, although the present disclosure is fully described in connection with embodiments with reference to the accompanying drawings, since the above-described embodiments are for exemplifying the technology in the present disclosure, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or their equivalents. Further, it is also possible to combine the respective components described in the above embodiments to form a new embodiment. Embodiments obtained by appropriately combining such changes and the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0077] (Overview of Embodiment) (1) The projection-type video display device of the present disclosure includes a video generation unit that generates video light based on a video input signal, a projection optical system that projects the video light onto a projection surface, an optical path changing unit that is provided on the optical path of the video light and has an actuator that shifts the display position of the video light on the projection surface in two different directions, and a control unit that controls the video generation unit and the optical path changing unit based on the video input signal. The frequency components of the waveforms of the shift amounts in each direction of the pixels of the display position on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and an odd harmonic component, and the minimum value of the shift amount of the pixels of the display position on the projection surface of the video light is 0.8 times or more of the maximum value of the shift amount.

[0078] Since the waveform of the shift amount of the pixels has a fundamental frequency component of a sine wave and an odd harmonic component, the displacement speed at the position where the sub-frame display is desired in the locus of the shift amount can be made slower compared to the uniform circular motion of the circular orbit by the sine wave, making it easier for a person watching the video to recognize the sub-frame and enabling the improvement of the image quality. In addition, since the minimum value of the shift amount of the pixels of the display position of the video light on the projection surface is 0.8 times or more of the maximum value of the shift amount, the odd harmonic component is less than that in the conventional driving by a trapezoidal wave, and the power consumption of the actuator can be reduced. Further, since the power consumption of the voice coil actuator 106 can be reduced, the amount of heat generation and noise from the optical path changing unit can also be reduced.

[0079] (2) The projection type video display device of the present disclosure includes a video generation unit that generates video light based on a video input signal, a projection optical system that projects the video light onto a projection surface, an optical path changing unit provided on the optical path of the video light and having an actuator that shifts the display position of the video light on the projection surface in two different directions, and a control unit that controls the video generation unit and the optical path changing unit based on the video input signal. The frequency components of the waveforms of the shift amounts in each direction of the pixels on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and odd harmonic components. The waveform of the shift amount in each direction has two or more and four or less inflection points within a half cycle, and one peak having an absolute value larger than that of the inflection points between two inflection points.

[0080] Since the waveform of the pixel shift amount has a fundamental frequency component of a sine wave and odd harmonic components, the displacement speed at the position where the sub-frame display is desired in the locus of the shift amount can be made slower compared to the uniform circular motion of the circular orbit by the sine wave, making it easier for a person watching the video to recognize the sub-frame and enabling improvement in image quality. Also, since the number of inflection points present within a half cycle of the waveform is four or less, the odd harmonic components are less than those in the conventional driving by a trapezoidal wave, and the power consumption of the voice coil actuator 106 can be reduced. Also, since the power consumption of the voice coil actuator 106 can be reduced, the heat generation amount and noise from the optical path changing unit 102 can also be reduced.

[0081] (3) In the projection type video display device of (2), the waveform of the shift amount in each direction has three maximum values within one half cycle, the central maximum value among the three maximum values has the largest absolute value, three minimum values within the other half cycle, and the central minimum value among the three minimum values has the largest absolute value.

[0082] (4) In the projection type video display device of (3), the minimum value of the pixel shift amount is 0.8 times or more of the maximum value of the shift amount.

[0083] (5) In any of the projection-type video display devices according to (1) to (4), the odd harmonic component has a component of 5% or more with respect to the fundamental frequency component.

[0084] (6) In the projection-type video display device according to (1) to (5), the minimum value of the pixel shift amount is 0.85 times or more and 0.95 times or less of the maximum value of the shift amount.

[0085] (7) In the projection-type video display device according to (1) to (6), the locus of the display position on the projection surface of the video light has a reverse path.

[0086] (8) In the projection-type video display device according to (7), it has a first mode in which the locus of the display position on the projection surface of the video light moves only in the forward direction, and a second mode in which the locus of the display position on the projection surface of the video light has a reverse path.

[0087] (9) In the projection-type video display device according to (1) to (8), the odd harmonic component includes the frequency component of the fifth harmonic.

[0088] (10) In the projection-type video display device according to (1) to (9), the odd harmonic component includes the frequency component of the third harmonic.

Industrial Applicability

[0089] The present disclosure can be used in projection-type video display devices such as projectors.

Explanation of Signs

[0090] 1 Screen 10 Light source unit 20 Video generation unit 22, 52, 56 Lenses 24 Total reflection prism 26 Air layer 28 Color prism 30 Blue reflection dichroic film 32 Red reflection dichroic film 34, 36, 38 DMD 50 Light guide optical system 52 lenses 54 rod integrator 56 lenses 58 mirror 60 projection optical system 70 control unit 72 actuator drive unit 74 video signal generation unit 76 display element drive unit 100 projection type video display device 102 optical path changing unit 104 parallel plate glass 106 voice coil actuator 108 mount frame 110 glass outer frame 112 glass inner frame 114 coil fixing frame 116 outer frame spring 118 inner frame spring 120 leaf spring[[ID=II]] 122, 126 yoke 124, 128 magnet 132, 134 coil 136 arrow 138 direction of Lorentz force 140, 142 arrows 144 input light ray 146 output light ray Ax waveform Ay waveform DL lower left DR lower right Dx waveform Dy waveform UL upper left UR upper right Pf inflection point Pk peak

Claims

1. A video generation unit that generates video light based on a video input signal, A projection optical system that projects the video light onto a projection surface, An optical path changing unit provided on the optical path of the video light and having an actuator that shifts the display position of the video light on the projection surface in two different directions, A control unit that controls the video generation unit and the optical path changing unit based on the video input signal, and The frequency components of the waveforms of the shift amounts in each direction of the pixels at the display position on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and an odd harmonic component, and the minimum value of the shift amount of the pixels at the display position on the projection surface of the video light is 0.8 times or more of the maximum value of the shift amount. A projection type video display device.

2. A video generation unit that generates video light based on a video input signal, A projection optical system that projects the video light onto a projection surface, An optical path changing unit provided on the optical path of the video light and having an actuator that shifts the display position of the video light on the projection surface in two different directions, A control unit that controls the video generation unit and the optical path changing unit based on the video input signal, and The frequency components of the waveforms of the shift amounts in each direction of the pixels at the display position on the projection surface of the video light driven by the actuator of the optical path changing unit each have a fundamental frequency component of a sine wave and an odd harmonic component, The waveforms of the shift amounts in each direction, Have two or more and four or less inflection points within a half cycle, and one peak having an absolute value larger than that of the inflection points between two inflection points. A projection type video display device.

3. The waveforms of the shift amounts in each direction have three maximum values within one half cycle, the central maximum value among the three maximum values has the largest absolute value, and have three minimum values within the other half cycle, and the central minimum value among the three minimum values has the largest absolute value. The projection type video display device according to Claim 2.

4. The minimum value of the pixel shift amount is 0.8 times or more of the maximum value of the shift amount. The projection type video display device according to Claim 2.

5. The harmonic component has a component of 5% or more with respect to the fundamental frequency component. The projection type video display device according to Claim 1 or 2.

6. The minimum value of the pixel shift amount is 0.85 times or more and 0.95 times or less of the maximum value of the shift amount. The projection type video display device according to Claim 1.

7. The locus of the display position on the projection surface of the video light has a reverse path. The projection type video display device according to Claim 1. Claim 8 a first mode in which the locus of the display position on the projection surface of the image light moves only in the forward direction; a second mode in which the locus of the display position on the projection surface of the image light has a reverse path; and having, The projection type image display device according to claim 7. Claim 9 The odd harmonic component includes a frequency component of the fifth harmonic, The projection type image display device according to claim 1 or 2. Claim 10 The odd harmonic component includes a frequency component of the third harmonic, The projection type image display device according to claim 9.

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