Projection-type image display device and its control method

Abstract

To provide a projection type image display device which can prevent displaying an unnatural image even when a motion speed and a space frequency change scene-by-scene.SOLUTION: The projection type image display device includes: an image display element which modulates illumination light from a light source to generate image light according to an input image signal; a transparent parallel plate which is subjected to swing drive control with 1 axis or 2 axes of mutually orthogonal 2 axes, and performs 1 axis or 2 axes pixel shift by the change of an optical path of the image light; a projection optical system which projects the image light transmitted through the transparent parallel plate with enlargement; a resampling processing unit which performs resampling processing to the input image signal; and a control unit which selectively executes one of not performing pixel shift without resampling processing, performing 1-axis pixel shift by executing resampling processing relating to 1-axis pixel shift, and performing 2-axes pixel shift by executing resampling processing relating to 2-axes pixel shift, according to the number of pixels and the frame rate of the input image signal.SELECTED DRAWING: Figure 13

Description

Technical Field

[0004] ,

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[0001] The present disclosure relates to a projection-type image display device such as a projector and a control method thereof.

Background Art

[0002] In a projection-type image display device according to the related art, it is determined whether an image signal is a fast-moving video, whether the spatial frequency of the entire image is uniform, or whether only a part of the spatial frequency is high. When the video is a fast-moving video or the spatial frequency is uniform, the pixel shift is turned off, and when the video is a slow-moving video or the spatial frequency is high, the pixel shift is turned on (see, for example, Patent Document 1). Thereby, it is possible to obtain a display with an optimally increased resolution for various image signals and suppress power consumption.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a projection-type image display device according to the related art, the on / off of the pixel shift may be repeated depending on the type of the image signal, and there is a problem that an unnatural image is felt due to a change in resolution depending on the scene. Note that the pixel shift is also called "wobbling" or "pixel shift".

[0005] The present disclosure provides a projection-type image display device and a control method thereof that can prevent the display of an unnatural image even when the speed or spatial frequency changes depending on the scene.

Means for Solving the Problems

[0006] The projection-type image display device according to the present disclosure is An image display element generates image light by modulating illumination light from a light source according to an input image signal, A transparent parallel plate that is driven to swing along one or two of two mutually orthogonal axes, wherein the transparent parallel plate performs a pixel shift along one or two axes relative to the image light by changing the optical path of the image light from the image display element, A projection optical system that magnifies and projects image light transmitted through the aforementioned transparent parallel plate, A resampling processing unit that performs resampling on the input image signal, Depending on the number of pixels and frame rate of the input image signal, (1) Control the resampling processing unit so as not to perform resampling on the input image signal, and control the transparent parallel plate so as not to perform pixel shift with respect to the image light, (2) The resampling processing unit is made to perform a resampling process relating to a one-axis pixel shift with respect to the input image signal, and the transparent parallel plate is controlled to perform a one-axis pixel shift with respect to the image light, (3) The resampling processing unit is made to perform a resampling process relating to a two-axis pixel shift on the input image signal, and the transparent parallel plate is controlled to perform a two-axis pixel shift with respect to the image light, A control unit that controls the system to selectively execute one of the following: It is equipped with. [Effects of the Invention]

[0007] Accordingly, according to this disclosure, the transparent parallel plate is selectively controlled to perform either a one-axis pixel shift or a two-axis pixel shift with respect to the image light, depending on the number of pixels and frame rate of the input image signal. This prevents the display of unnatural images even when the speed of motion or spatial frequency changes depending on the scene. [Brief explanation of the drawing]

[0008] [Figure 1]A schematic diagram showing an example of the configuration of the projection optical system of the projector 100 according to the embodiment. [Figure 2] Figure 1 shows a block diagram illustrating an example configuration of the image processing circuit 420 of the projector 100. [Figure 3] Schematic diagram showing an example configuration of the optical element driving device 430 of the projector 100 shown in Figure 1. [Figure 4] Figure 3 is a schematic diagram showing an example configuration of the actuator 401 of the optical element driving device 430. [Figure 5] Schematic diagram illustrating the principle of optical path modification using parallel glass plates 400 shown in Figure 1. [Figure 6] Plan view of parallel flat glass 400 in Figure 1 [Figure 7] Schematic diagram illustrating the operation of parallel flat glass 400 in Figure 1. [Figure 8] Figure 2 shows a schematic diagram illustrating an example of the configuration of the input image signal input to the image processing circuit 420. [Figure 9] Front view showing a subframe image for a double-density image generated from the input image signal in Figure 8. [Figure 10] Figure 9 is a front view showing the subframe image after pixel shifting to create a double-density image. [Figure 11] Front view showing a subframe image for a quadruple-density image generated from the input image signal in Figure 8. [Figure 12] Figure 9 is a front view showing the subframe image after pixel shifting to create a 4x denser image. [Figure 13] A flowchart showing the pixel shift control process performed by the pixel shift control unit 405 and control circuit 440 in Figure 2. [Figure 14] Figure 13 is a schematic diagram in tabular format showing an example of the execution of the pixel shift control process. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, a detailed description of well-known matters or a redundant description of substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0010] Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0011] (Inventor's finding) In the prior art, as described above, depending on the type of input image signal, the on / off of pixel shift processing may be repeated, and due to the change in resolution depending on the scene, there has been a problem that the image feels unnatural.

[0012] To solve this problem, in the embodiments according to the present disclosure, according to the frame rate and the number of pixels (or resolution) of the input image signal, it is characterized by switching to select one of three patterns: turning off pixel shift processing, performing one-axis pixel shift processing, and performing two-axis pixel shift processing. Switch.

[0013] Hereinafter, embodiments will be described using FIGS. 1 to 14.

[0014] (Configuration of the projection optical system of the projector) FIG. 1 is a schematic diagram showing a configuration example of a projection optical system of a projector 100, which is an example of a projection-type image display device according to an embodiment. Referring to FIG. 1, the configuration of the projection optical system of the projector 100 will be described below.

[0015] In Figure 1, the projector 100 includes a light source 130 composed of a discharge tube 110 and a reflector 120 that reflects the white light emitted by the discharge tube 110. The discharge tube 110 emits a white light beam containing red, green, and blue light, each with different wavelength ranges. The discharge tube 110 is made of, for example, an ultra-high pressure mercury lamp or a metal halide lamp. The reflector 120 reflects the light beam emitted from the discharge tube 110, which is positioned at one focal point, and emits it forward as parallel light.

[0016] White light from light source 130 is input to the illumination optical system. The illumination optical system includes lens 160, rod 170, lens 180, and mirror 190. The illumination optical system guides the light beam emitted from light source 130 to digital mirror devices (hereinafter referred to as DMDs) 240, 250, and 260. Rod 170 is a columnar glass member that causes total internal reflection of light. The light beam emitted from light source 130 is reflected multiple times within rod 170. As a result, the light intensity distribution at the exit surface of rod 170 becomes substantially uniform.

[0017] Lens 180 is a relay lens that focuses the light beam from the exit surface of rod 170 onto DMDs 240, 250, and 260. Mirror 190 reflects the light beam that has passed through lens 180. The reflected light beam enters field lens 200. Field lens 200 is a lens that converts the incident light into a nearly parallel light beam. The light beam that has passed through field lens 200 enters total internal reflection prism.

[0018] A total internal reflection prism consists of prism 270 and prism 280. An air layer 210 exists in close proximity between prisms 270 and 280. The air layer 210 is a thin layer of air. The air layer 210 totally reflects light beams incident at angles greater than the critical angle. The totally reflected light beam then enters the color prism.

[0019] The color prism consists of prisms 221, 231, and 290. A dichroic film 220 that reflects blue light is provided on the near surfaces of prisms 221 and 231. A dichroic film 230 that reflects red light is provided on the near surfaces of prisms 231 and 290. DMDs 240, 250, and 260 are also provided for the color prism.

[0020] The DMD240, DMD250, and DMD260 each have 1920 × 1080 micromirrors. The DMD240, DMD250, and DMD260 deflect each micromirror according to the image signal. This allows the DMD240, DMD250, and DMD260 to modulate the light incident on the DMD by separating the light into light that enters the projection optical system 300 and light that is reflected outside the effective range of the projection optical system 300, according to the image signal. Green light is incident on the DMD240, red light on the DMD250, and blue light on the DMD260.

[0021] Of the light beams reflected by DMD240, DMD250, and DMD260, the light beams that enter the projection optical system 300 are combined by the color prisms. The combined light beams enter the total internal reflection prism. The light beams that enter the total internal reflection prism enter the air layer 210 at an angle below the critical angle. Therefore, these light beams pass through the air layer 210 and enter the projection optical system 300.

[0022] The projection optical system 300 is an optical system for amplifying the incident light beam. The projection optical system 300 has a focus function and a zoom function, and projects the image light from the DMD onto the projection surface, thereby displaying an image on the projection surface.

[0023] The projector 100 is equipped with a parallel plate glass 400, which is an example of a transparent parallel plate, as an optical element positioned in a plane perpendicular to the optical axis of the projection optical system and capable of the operation described later. By operating this parallel plate glass 400, the projector 100 shifts the display position of the pixels that make up the image generated by the DMD on the screen, which is the projection surface, by an interval of less than the pixel pitch. As a result, the projector 100 can project a high-resolution image.

[0024] (Configuration between the prism and the projection lens) Next, an image processing circuit 420 and an optical element driving device 430 for driving the parallel flat glass 400, which is placed between the prism block consisting of a total reflection prism and a color prism and the projection optical system 300, will be described.

[0025] Figure 2 is a block diagram showing an example configuration of the image processing circuit 420 of the projector 100 shown in Figure 1. Figure 3 is a schematic diagram showing an example configuration of the optical element driving device 430 of the projector 100 shown in Figure 1. Note that the image processing circuit 420 shown in Figure 2 is installed inside the projector 100, excluding external devices such as a personal computer (PC) connected to it.

[0026] In this embodiment, a planar circular parallel plate glass 400 is used as the optical element. In Figures 2 and 3, the ends of the parallel plate glass 400 are connected by connecting members 406a, 406b, 406c, and 406d to the movable parts 407a, 407b, 407c, and 407d (collectively referred to as 407) of four actuators 401a, 401b, 401c, and 401d (collectively referred to as actuator 401).

[0027] Figure 4 is a schematic diagram showing an example configuration of the actuator 401 of the optical element driving device 430 in Figure 3. In this embodiment, a voice coil motor (VCM) is used as an example of the actuator 401. In Figure 4, permanent magnets with different magnetic poles (a north pole permanent magnet 4012 and a south pole permanent magnet 4013) are arranged facing each other at a certain distance apart inside a rectangular yoke 4011, and a movable part 407 is positioned between the opposing permanent magnets 4012 and 4013.

[0028] A guide window 4070 is provided in the movable part 407, through which a yoke 4011 is inserted. A coil 4014, provided on the movable part 407, is positioned between the opposing permanent magnets 4012 and 4013. When a drive signal current is passed through the coil 4014, the movable part 407 moves in one axis direction in the direction of arrow 407D. The amount of movement of the movable part 407 is determined by the magnitude of the signal current flowing through the coil 4014, moving in either the positive or negative direction from the reference position. The amount of movement of the movable part 407 is detected by a position detection circuit 403, shown in Figure 2, which detects a position sensor 402 attached to the movable part 407. A small gap exists between the movable part 407 to which the coil 4014 is attached and the permanent magnets 4012 and 4013. Therefore, even if a force perpendicular to the uniaxial direction driven by the drive signal current is applied to the movable part 407, it can be displaced by a distance allowed by its small gap, and the movable part 407 can tilt.

[0029] The connecting member 406 to which the movable part 407 of the actuator 401 is connected is, as shown in Figure 6, connected at the central ends EA, EB, EC, and ED of each side on the AC axis and BD axis which are mutually orthogonal to each other at the plane center O of the parallel flat glass 400.

[0030] In Figure 2, the four actuators 401a to 401d are driven by drive circuits 404a, 404b, 404c, and 404d, which are controlled by control signals from the pixel shift control unit 405. The drive signal current from the drive circuits 404a to 404d drives the actuators 401a to 401d so that their movable parts 407a to 407d move forward and backward in a uniaxial direction. The position of the movable parts 407a to 407d is detected by position sensors 402a to 402d provided on them, which are detected by position detection circuits 403a to 403d. The detection output from the position detection circuits 403a to 403d is input to the pixel shift control unit 405, which constantly monitors the position of the movable parts 407a to 407d of the actuators 401a to 401d based on this detection signal and servo-controls the actuators 401a to 401d.

[0031] In Figure 2, the input image signal is input to the image signal input unit 414. The image signal input unit 414 temporarily stores the signal in its built-in buffer memory and then outputs it to the image signal processing unit 415. The image signal processing unit 415 performs predetermined image signal processing on the input image signal, such as scaling, color correction, and interframe interpolation (FRC), and outputs the processed image signal to the image signal discrimination unit 410 and the resampling processing unit 413. The image signal discrimination unit 410 and the resampling processing unit 413 are implemented in a control circuit 440, such as an FPGA (Field-Programmable Gate Array).

[0032] The pixel shift control unit 405 and the control circuit 440 execute the pixel shift control process shown in Figure 13, described later, based on the number of pixels (resolution) and frame rate of the input subframe image signal. Here, the image signal discrimination unit 410 determines whether or not to perform 1-axis or 2-axis pixel shift processing based on the number of pixels (resolution) and frame rate of the input subframe image signal, for example, according to the judgment criteria in Table 1 below, and outputs a judgment result signal indicating the discrimination result to the pixel shift control unit 405 and the resampling processing unit 413. Note that RESsignal is the resolution or number of pixels of the input image signal (horizontal number of pixels × vertical number of pixels, and the same applies hereinafter), and RESdmd is the resolution or number of pixels of DMD240, 250, and 260.

[0033] [Table 1]

[0034] Specifically, the pixel shift control unit 405 generates a synchronization signal to be supplied to the drive circuits 404a to 404d based on the synchronization signal generated by the DMD drive unit 411, according to the number of pixels (resolution) and frame rate of the input subframe image signal.

[0035] Furthermore, the amount of movement of the movable parts 407a to 407d of each actuator 401a to 401d is adjusted by operating the shift amount operation unit 412, which sends a signal indicating the adjustment amount to the pixel shift control unit 405, and the pixel shift control unit 405 controls the drive circuits 404a to 404d. The shift amount operation unit 412 may be, for example, an operation key provided on the main body of the projector 100, or a key assigned to a remote controller that operates the projector 100.

[0036] Figure 5 is a schematic diagram illustrating the principle of optical path modification using the parallel glass plates 400 shown in Figure 1.

[0037] As shown in Figure 5, when the plane of the parallel glass plate 400 is perpendicular to the input light ray Li, the input light ray Li travels in a straight line without refraction at the interface between the parallel glass plate 400 and the air. The input light ray passes through the parallel glass plate 400 without refraction, and even at the interface where it exits to the air, the light ray and the interface are perpendicular because the parallel glass plate 400 is a parallel plane, so it travels in a straight line without refraction. For this reason, if the input light ray is image light, no image shift occurs.

[0038] On the other hand, when the parallel glass plates 400 are not perpendicular to the input light ray, as shown by the dashed line in Figure 5, the input light ray is refracted at the interface between the parallel glass plates 400 and the air. After the input light ray Li is refracted and enters the parallel glass plates 400, it passes through the parallel glass plates 400 and exits into the air. At this interface, however, because the parallel glass plates 400 are parallel planes, the light ray and the interface are not perpendicular, and therefore the light ray is refracted again.

[0039] Since the angle of refraction when light enters the parallel glass 400 is equal to the angle of refraction when light exits the parallel glass 400, if the input light ray Li is the image light, the output light ray Lo, which is the image light, will be translated in the direction of the tilt of the parallel glass. As a result, the display position of the image output and projected from the parallel glass 400 will shift.

[0040] Figure 6 is a plan view of the parallel flat glass 400 in Figure 1, and Figure 7 is a schematic diagram illustrating the operation of the parallel flat glass 400 in Figure 1.

[0041] Using the principle described above, as shown in Figure 6, the glass ends EA and EC, and EB and ED, which are on the mutually orthogonal AC and BD axes passing through the center O of the parallel flat glass 400, are connected to the movable parts 407a to 407d, respectively, by connecting members of the actuators 401a to 401d, so as to be able to swing freely. By driving the actuators 401a to 401d, while keeping the position of the center O constant, for example, as shown in Figure 7, the AC axis is moved upward by a predetermined amount and the end EA is moved downward by a predetermined amount, with the BD axis as the rotation axis, and the BD axis is moved downward by a predetermined amount and the end ED is moved upward by a predetermined amount, with the AC axis as the rotation axis. As a result, the optical path of the image light incident on the parallel flat glass 400 is changed and pixels are displayed at predetermined positions. From this state, pixel shifting can be performed to move the display position of the pixels by controlling each end in the vertical direction in the same manner.

[0042] The resampling processing unit 413 generates two or four subframe image signals corresponding to the movement of the projection position by the optical element drive device for each frame of the input image signal, based on the input judgment result signal, and outputs them to the DMD drive unit 411. The number of pixels in the subframe image signals is the same as the corresponding number of pixels for the DMD240, 250, and 260.

[0043] (Output operation of double-density images) The pixel shift control unit 405 generates a synchronization signal to supply to the drive circuits 404a to 404d based on the synchronization signal generated by the DMD drive unit 411 from the two subframe signals generated by the resampling processing unit 413. The DMD drive unit 411 generates a DMD drive signal so as to output the two subframe signals generated by the resampling processing unit 413 at twice the output frame rate. The drive circuits 404a to 404d for the actuators 401a to 401d generate actuator drive signals so as to drive the actuators 401a to 401d in synchronization with the DMD drive unit 411 and move the projection position of the pixels.

[0044] Figure 8 is a schematic diagram showing an example of the configuration of the input image signal input to the image processing circuit 420 in Figure 2, and Figure 9 is a front view showing a subframe image for a double-density image generated from the input image signal in Figure 8. The specific operation examples of the image processing circuit 420 in Figure 2 will be explained below using Figures 8 and 9.

[0045] In projector 100, DMD240, 250, and 260 are capable of outputting images with 1920 pixels horizontally and 1080 pixels vertically. Furthermore, by driving the parallel flat glass 400 with actuators 401a to 401d, the projection position is set to be shifted by half a pixel horizontally and half a pixel vertically. Here, shifting by half a pixel (or half a pixel) means moving the pixel to a position half the pitch between pixels.

[0046] Figure 8 shows the base input image signal for creating subframe images in the image output system 4000 of projector 100, which is a so-called 4K2K image with 3840 pixels horizontally and 2160 pixels vertically. The number of pixels in this input image signal is DMD240, This is four times the number of pixels, 250 or 260. This input image signal may be an image signal directly input from an external device, or it may be a signal obtained by upconverting a lower-resolution input image within the system.

[0047] Next, the method for generating subframe image signals in the image signal processing unit 415 will be described.

[0048] Figure 9 shows a method for generating two subframe signals (resampled image signals) by resampling a single-frame input image signal shown in Figure 8 at different sample positions. In the input image signal in Figure 8, the pixel column numbers are assigned horizontally as 0, 1, 2, 3, 4, 5, ... and the pixel row numbers are assigned vertically as 0, 1, 2, 3, ...

[0049] Here, (1) The first subframe signal is obtained by sampling a pixel whose numerical value indicating the column number (counting from column number 0 in the horizontal direction) divided by 2 has a remainder of 0, and whose numerical value indicating the row number (counting from row number 0 in the vertical direction) divided by 2 has a remainder of 0.

[0050] (2) The second subframe signal is obtained by sampling a pixel whose numerical value indicating the column number (counting from column number 0 in the horizontal direction) divided by 2 has a remainder of 1, and whose numerical value indicating the row number (counting from row number 0 in the vertical direction) divided by 2 has a remainder of 1.

[0051] Figure 10 is a front view showing the subframe image from Figure 9 after the pixels have been shifted to become a twice as dense image.

[0052] The DMD240, 250, and 260 output two subframes at twice the output frame rate. Specifically, if the output frame rate is 60Hz, the subframes are output at 120Hz, and actuators 401a to 401d are driven at 60Hz. Figure 10 schematically shows the displacement (VCM displacement) instructed to actuators 401a to 401d and the movement of the subframe images in this case. In this case, as shown in Figure 10, displacement A is instructed to actuator 401a, and displacement C, which is the inverse of displacement A, is instructed to actuator 401c. The displacements of actuators 401b and 401d are not changed. As a result, the parallel flat glass 400 oscillates around the BD axis as the axis of rotation, which changes the optical path of the input image light, and projects the first subframe image and the second subframe image that are offset by half a pixel from each other.

[0053] (Output operation of 4x density image) The resampling processing unit 413 generates four subframe image signals for each frame of the input image signal, corresponding to the movement of the projection position by the parallel flat glass 400 and actuators 401a to 401d.

[0054] The four subframe image signals generated by the resampling processing unit 413 are sent to the DMD drive unit 411, which generates a DMD drive signal to output at four times the output frame rate. The pixel shift control unit 405 generates an actuator drive signal to drive the parallel flat glass 400 in synchronization with the DMD drive unit 411 to move the projection position of the pixels, and outputs it to the drive circuits 404a to 404d.

[0055] Figure 11 is a front view showing a subframe image for a quadruple-density image generated from the input image signal in Figure 8, and Figure 12 is a front view showing the subframe image from Figure 9 after pixel shifting to create a quadruple-density image. Referring to Figures 11 and 12, the operation of the image output system when the projection position can be moved in two directions will be explained. Note that the corresponding resolution of the display element and the resolution of the input image signal are the same as those explained in the output operation of a double-density image.

[0056] First, the method for generating subframe signals in the image signal processing unit 415 will be explained. Figure 11 shows a method for creating four subframe signals (resampled image signals) by resampling at different sample positions from the input image signal of one frame shown in Figure 8.

[0057] In the input image signal shown in Figure 8, (1) The first subframe is a signal obtained by sampling a pixel whose remainder when the number indicating its position in the horizontal direction (counting from 0) is divided by 2 is 0, and whose remainder when the number indicating its position in the vertical direction (counting from 0) is divided by 2 is also 0.

[0058] (2) The signal obtained by sampling a pixel in which the remainder when the number indicating the horizontal position (counting from 0) is divided by 2 is 1, and the remainder when the number indicating the vertical position (counting from 0) is divided by 2 is 0, is defined as the second subframe.

[0059] (3) The signal obtained by sampling a pixel whose remainder when the number indicating its position in the horizontal direction (counting from 0) is divided by 2 is 1, and whose remainder when the number indicating its position in the vertical direction (counting from 0) is divided by 2 is 1, is defined as the third subframe.

[0060] (4) The fourth subframe is a signal obtained by sampling a pixel in which the remainder when the number indicating the horizontal position (counting from 0) is divided by 2 is 0, and the remainder when the number indicating the vertical position (counting from 0) is divided by 2 is 1.

[0061] The DMD240, 250, and 260 output four subframes at four times the output frame rate. Specifically, if the output frame rate is 60Hz, the subframes are output at 240Hz, and actuators 401a to 401d are driven at 60Hz.

[0062] Figure 12 schematically shows the displacement (VCM displacement) instructed to actuators 401a to 401d and the movement of the subframe images at this time. In this case, displacement A is instructed to actuator 401a, and displacement C, which is the inverse of displacement A, is instructed to actuator 401c. Displacement B is instructed to actuator 401b, and displacement D, which is the inverse of displacement B, is instructed to actuator 401d. Furthermore, the displacement waveform instructed to actuators 401b and 401d is shifted in phase by 90° compared to the displacement waveform instructed to actuators 401a and 401c. As a result, the parallel flat glass 400 oscillates around the BD axis and AC axis as its rotation axes, so the optical path of the input image light is displaced in the horizontal and vertical directions, and the first subframe image, second subframe image, third subframe image, and fourth subframe image, which are shifted by half a pixel from each other, are projected sequentially.

[0063] (Pixel shift control processing) Figure 13 is a flowchart showing the pixel shift control process executed by the pixel shift control unit 405 and control circuit 440 in Figure 2.

[0064] In step S1 of Figure 13, it is determined whether the frame rate FR of the input image signal is FR ≥ 192 fps. If YES, the process proceeds to step S2; otherwise, it proceeds to step S3. In step S2, the resampling processing unit 413 is not allowed to perform resampling, nor is the pixel shift processing performed on the parallel flat glass 400 of the optical element driving device 430, and the pixel shift control processing is terminated.

[0065] In step S3, it is determined whether the frame rate FR is FR ≥ 60fps. If YES, the process proceeds to step S4; otherwise, it proceeds to step S7. In step S4, it is determined whether the resolution (number of pixels) RESsignal of the input image signal is greater than the resolution (number of pixels) RESdmd of DMD240, 250, and 260. If YES, the process proceeds to step S5; otherwise, it proceeds to step S6. In step S5, the resampling processing unit 413 is instructed to perform 2-axis resampling, and the optical element driving device 430 is instructed to perform 2-axis pixel shift processing on the parallel plate glass 400, and the pixel shift control process is terminated. In step S6, the resampling processing unit 413 is not instructed to perform resampling, and the pixel shift control process is not instructed to perform pixel shift processing on the parallel plate glass 400 of the optical element driving device 430, and the pixel shift control process is terminated.

[0066] In step S7, it is determined whether the resolution (number of pixels) RESsignal of the input image signal is greater than the resolution (number of pixels) RESdmd of DMD240, 250, and 260. If the answer is YES, the process proceeds to step S8; otherwise, it proceeds to step S9. In step S8, the resampling processing unit 413 is instructed to perform 1-axis resampling, and the optical element driving device 430 is instructed to perform 1-axis pixel shift processing on the parallel plate glass 400, and the pixel shift control process is terminated. In step S9, however, the resampling processing unit 413 is not instructed to perform resampling, and the pixel shift control process is not instructed to perform pixel shift processing on the parallel plate glass 400 of the optical element driving device 430, and the pixel shift control process is terminated.

[0067] Here, 60fps corresponds to a first threshold for frame rate and 192fps corresponds to a second threshold for frame rate, but this disclosure is not limited to these, and other frame rates may be used while maintaining the relative magnitudes of the thresholds.

[0068] (Effects of the embodiment) Figure 14 is a schematic diagram in tabular form showing an example of the execution of the pixel shift control process in Figure 13.

[0069] In step S5 of Figure 13, if the number of pixels in the input image signal is greater than the number of pixels in the DMD240, 250, and 260, and the frame rate FR is 60Hz or less, a high-definition image can be projected by 2-axis pixel shift control.

[0070] Furthermore, in step S8 of Figure 13, if the number of pixels in the input image signal is greater than the number of pixels in the DMD240, 250, and 260, and the frame rate FR is 96Hz to 120Hz, a high-definition and smooth image can be projected by performing 1-axis pixel shift control.

[0071] Furthermore, in step S2 of Figure 13, if the input image signal has a frame rate FR of 192Hz or higher, or in other cases, the pixel shift processing is turned off to project a smooth image.

[0072] This allows for the projection of the optimal image for various image signals.

[0073] As described above, according to this embodiment, the transparent parallel plate is selectively controlled to perform either a one-axis pixel shift or a two-axis pixel shift with respect to the image light, depending on the number of pixels and frame rate of the input image signal. This prevents the display of unnatural images even when the speed of motion or spatial frequency changes depending on the scene.

[0074] (modified version) In the embodiments described above, DMD240, 250, and 260 are used, but this disclosure is not limited to these, and other types of image display elements may be used instead of DMDs.

[0075] As described above, embodiments have been explained as examples of the technology in this disclosure. For this purpose, accompanying drawings and a detailed description have been provided.

[0076] Therefore, the components described in the attached drawings and detailed descriptions may include not only components essential for solving the problem, but also components that are not essential for solving the problem, provided that they illustrate the technology described above. For this reason, the mere presence of these non-essential components in the attached drawings and detailed descriptions should not be immediately assumed to mean that they are essential.

[0077] Furthermore, since the embodiments described above are for illustrative purposes of the technology described herein, various modifications, substitutions, additions, omissions, etc., can be made within the scope of the claims or their equivalents. [Industrial applicability]

[0078] This disclosure is applicable to projection-type image display devices that can project high-definition projected images by shifting the display position of pixels. [Explanation of Symbols]

[0079] 100 projectors 130 light source 240, 250, 260 DMD 400 Parallel Flat Glass 401a, 401b, 401c, 401d actuators 402a, 402b, 402c, 402d position sensors 403a, 403b, 403c, 403d Position detection circuit 404a, 404b, 404c, 404d drive circuits 405 Pixel Shift Control Unit 410 Image signal discrimination unit 411 DMD drive unit 412 Shift amount control unit 413 Resampling Processing Unit 414 Image signal input section 415 Image signal processing unit 420 Image processing circuit 430 Optical element driving device 440 Control circuits

Claims

1. An image display element generates image light by modulating illumination light from a light source according to an input image signal, A transparent plate that is driven to swing along one or two of two mutually orthogonal axes, wherein the transparent plate performs a pixel shift along one or two axes relative to the image light by changing the optical path of the image light from the image display element, A projection optical system that magnifies and projects the image light transmitted through the transparent plate, A resampling processing unit that performs resampling on the input image signal, Depending on the number of pixels and frame rate of the input image signal, (1) Control the resampling processing unit so as not to perform resampling on the input image signal, and control the transparent plate so as not to perform pixel shift with respect to the image light, (2) The resampling processing unit is made to perform a resampling process relating to a one-axis pixel shift on the input image signal, and the transparent plate is controlled to perform a one-axis pixel shift with respect to the image light, (3) A control unit that controls the resampling processing unit to perform a resampling process relating to a two-axis pixel shift with respect to the input image signal, and controls the transparent plate to perform a two-axis pixel shift with respect to the image light, to selectively perform one of the following: In the first case where the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is greater than or equal to a predetermined first threshold, the control unit outputs a signal indicating that display is not possible.

2. The projection-type image display device according to claim 1, wherein when the frame rate of the input image signal is equal to or greater than the first threshold, the control unit controls the transparent plate so as not to cause the resampling processing unit to perform a pixel shift resampling process on the input image signal and to not perform a pixel shift on the image light.

3. In the second case, where the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is less than or equal to a second threshold less than the first threshold, the control unit causes the resampling processing unit to perform a two-axis pixel shift resampling process on the input image signal and controls the transparent plate to perform a two-axis pixel shift with respect to the image light. In the third case where the number of pixels in the input image signal is greater than the number of pixels in the image display element, the frame rate of the input image signal is less than the first threshold, and exceeds the second threshold, the control unit causes the resampling processing unit to perform a resampling process relating to a one-axis pixel shift on the input image signal, and controls the transparent plate to perform a one-axis pixel shift relative to the image light. In cases other than the first to third cases described above, the control unit controls the resampling processing unit so as not to perform resampling on the input image signal, and controls the transparent plate so as not to perform pixel shift with respect to the image light. The projection-type image display device according to claim 1 or 2.

4. The projection-type image display device according to claim 3, wherein the first threshold is 192 fps and the second threshold is 60 fps.

5. Equipped with a display unit, In the first case where the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is greater than or equal to a predetermined first threshold, the control unit outputs a signal to the display unit indicating that display is not possible, as described in claim 1.

6. An image display element generates image light by modulating illumination light from a light source according to an input image signal, A transparent plate that is driven to swing along one or two of two mutually orthogonal axes, the transparent plate that performs a pixel shift of one or two axes relative to the image light by changing the optical path of the image light from the image display element, and a projection optical system that magnifies and projects the image light that has passed through the transparent plate. A resampling processing unit that performs resampling on the input image signal, A control method for a projection-type image display device comprising a transparent plate and a control unit for controlling the resampling processing unit, wherein the control unit controls the number of pixels and frame rate of the input image signal according to the number of pixels and frame rate of the input image signal. (1) Control the resampling processing unit so as not to perform resampling on the input image signal, and control the transparent plate so as not to perform pixel shift with respect to the image light, (2) The resampling processing unit is made to perform a resampling process relating to a one-axis pixel shift on the input image signal, and the transparent plate is controlled to perform a one-axis pixel shift with respect to the image light, (3) Controlling the transparent plate to selectively perform one of the following: causing the resampling processing unit to perform a two-axis pixel shift on the input image signal, and controlling the transparent plate to perform a two-axis pixel shift with respect to the image light. A method for controlling a projection-type image display device, comprising the step of: when the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is greater than or equal to a predetermined first threshold, the control unit outputs a signal indicating that display is not possible.

7. The control unit further includes the step of controlling the transparent plate so as not to perform pixel shift resampling processing on the input image signal and not to perform pixel shift on the image light when the frame rate of the input image signal is equal to or greater than the first threshold, A control method for a projection-type image display device according to claim 6.

8. A control method for a projection image display device according to claim 6, comprising the step of: when the number of pixels of the input image signal is greater than the number of pixels of the image display element and the frame rate of the input image signal is greater than or equal to a predetermined first threshold, the control unit outputs a signal to the display unit of the projection image display device indicating that display is not possible.

9. The control step is as follows: When the control unit is in the second case where the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is less than or equal to a second threshold less than the first threshold, the control unit causes the resampling processing unit to perform a two-axis pixel shift resampling process on the input image signal and controls the transparent plate to perform a two-axis pixel shift on the image light. In the third case where the number of pixels in the input image signal is greater than the number of pixels in the image display element, the frame rate of the input image signal is less than the first threshold, and exceeds the second threshold, the control unit causes the resampling processing unit to perform a resampling process relating to a one-axis pixel shift on the input image signal, and controls the transparent plate to perform a one-axis pixel shift relative to the image light. A control method for a projection-type image display device according to claim 6 or 7, wherein, in cases other than the first to third cases, the control unit controls the resampling processing unit so as not to perform resampling on the input image signal, and controls the transparent plate so as not to perform pixel shift with respect to the image light.

10. The control method for a projection-type image display device according to claim 9, wherein the first threshold is 192 fps and the second threshold is 60 fps.

11. An image display element generates image light by modulating illumination light from a light source according to an input image signal, A transparent plate that is controlled by oscillation drive, which performs pixel shift with respect to the image light by changing the optical path of the image light from the image display element, A projection optical system that magnifies and projects the image light transmitted through the transparent plate, The system includes a control unit that controls the transparent plate according to the number of pixels and frame rate of the input image signal, In the first case where the number of pixels in the input image signal is greater than the number of pixels in the image display element and the frame rate of the input image signal is greater than or equal to a predetermined first threshold, the control unit outputs a signal indicating that display is not possible.

12. Equipped with a display unit, In the first case described above, the control unit outputs a signal to the display unit indicating that display is unavailable. The projection-type image display device according to claim 11.

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