JP2019211677A - Projection device, control method and program for the same - Google Patents

Abstract

To achieve higher resolution using pixel shift technique more reliably.SOLUTION: A projection device 100 comprises: an image generation section 341 generating a plurality of images from an input image; a light modulation element 170 modulating light from a light source 160 according to the plurality of images; a pixel shift element 190 shifting light outputted from the light modulation element 170 in a prescribed direction; a shift control section 195 controlling the pixel shift element 190; a CPU 101 detecting parameters related to a shift amount by the pixel shift element 190; and a position correction section 343 correcting at least one of the plurality of images based on the parameters related to a shift amount.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a projection apparatus using a pixel shift technique for artificially increasing resolution, a control method therefor, and a program.

  As one of techniques for increasing the resolution of an image projected and displayed by a projection apparatus, there is a pixel shift technique that realizes high resolution by shifting the optical path of an image to be projected. In the pixel shift technique, a plurality of field images are generated based on an input image, and the projection position of each field image is shifted by ½ pixel (0.5 pixel) and displayed. Realize higher resolution.

  In the case where pixel shift is performed by displaying a plurality of field images in a time division manner using the projection device, a pixel shift element is disposed on the projection optical path. The pixel shift element includes a parallel plate method and a liquid crystal method. In the parallel plate method, the image projection position is shifted by changing the angle of the transmissive optical member arranged on the projection optical path. In the liquid crystal method, a liquid crystal and a birefringent material are combined, and a voltage applied to the liquid crystal is changed to change a polarization direction of light incident on the birefringent material, thereby shifting an image projection position.

  In order to increase the resolution by using such a pixel shift technique, it is necessary to project a plurality of field images by accurately shifting the field images by ½ pixel. However, in practice, due to the mechanical or optical characteristics of the pixel shift element, it is not easy to display an image that is ideally shifted by ½ pixel, and as a result, a desired resolution cannot be obtained. There is a case. To deal with such a problem, Patent Document 1 discloses a technique for determining whether or not an image can be shifted by 1/2 pixel using a test pattern.

JP 2013-247458 A

  With the technique described in Patent Document 1, it is possible to determine whether or not an image can be shifted by 1/2 pixel. However, Patent Document 1 does not describe or suggest that the shift is adjusted or corrected when the shift amount is larger or smaller than 1/2 pixel. There is a problem that it cannot be raised.

  It is an object of the present invention to provide a projection apparatus that can reliably achieve high resolution by pixel shift technology.

  The projection apparatus according to the present invention includes a generation unit that generates a plurality of images from an input image, a modulation unit that modulates light from a light source according to the plurality of images, and a light output from the modulation unit. Shift means for shifting in the direction; control means for controlling the shift means; detection means for detecting a parameter relating to a shift amount by the shift means; and correcting at least one of the plurality of images based on the parameters. And a correcting means.

  According to the present invention, it is possible to reliably realize high resolution by the pixel shift technique.

It is a block diagram which shows the structure of the projection apparatus which concerns on 1st Embodiment. It is a figure explaining the ideal pixel shift by a parallel plate system. It is a block diagram which shows the structure of the image process part which a projector has. It is a figure explaining the projection position of the image for pixel shift display. It is a figure explaining sampling of the frame image with respect to an input image. It is a figure explaining the data of a frame correction table. FIG. 7 is a diagram schematically illustrating position correction according to FIG. It is a schematic diagram explaining the interpolation calculation of the coordinate in the case of performing position correction. It is a figure explaining the example of the optical path shift by a parallel plate system. It is a schematic diagram explaining the relationship between the angle of the optical member of the pixel shift element and position correction amount in 2nd Embodiment. It is a figure explaining the relationship between the cumulative driving frequency of a pixel shift element, and the attitude | position of an optical member in 3rd Embodiment. It is a block diagram which shows the structure of the image process part in 4th Embodiment. It is a figure explaining the projection position of the frame image in a 4th embodiment. It is a schematic diagram explaining the production | generation method of the frame image in 4th Embodiment. It is a figure explaining the structure of the pixel shift element in 5th Embodiment. It is a block diagram which shows the structure of the image process part in 6th Embodiment. It is a figure explaining the calculation method of the reduction sampling phase in a 6th embodiment. It is a block diagram which shows the structure of the image process part in 7th Embodiment. It is a figure which shows the example of the filter coefficient characteristic at the time of the reduced image generation in 7th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
In the first embodiment, a configuration and method for correcting an image projection position by pixel shift in a parallel plate method will be described. FIG. 1 is a block diagram showing a schematic configuration of a projection apparatus 100 according to the first embodiment. The projection apparatus 100 includes a CPU 110, a RAM 111, a ROM 112, an operation unit 113, a communication unit 114, an image input unit 120, a light source control unit 130, an image processing unit 140, a light modulation control unit 150, a light source 160, a color separation unit 165, and a color composition. Part 180. The projection apparatus 100 also includes light modulation elements 170R, 170G, and 170B, a projection optical system 183, an optical system control unit 185, a pixel shift element 190, a shift control unit 195, and a bus 199.

  As shown in FIG. 1, the bus 199 connects predetermined units constituting the projection apparatus 100 so that they can communicate with each other. The CPU 110 controls the overall operation of the projection apparatus 100 by controlling the operation of each unit of the projection apparatus 100. The ROM 112 stores a control program describing the processing procedure of the CPU 110 and the like. The RAM 111 temporarily stores a control program and data as a work memory for the CPU 110. The CPU 110 temporarily stores still image data and moving image data received through the communication unit 114 in the RAM 111 and executes a program stored in the ROM 112 to reproduce a still image or moving image (video).

  The operation unit 113 is, for example, a signal reception unit such as an infrared reception unit that receives a signal from a switch, a dial, or a remote controller (remote controller), and receives an instruction from the user and transmits an instruction signal to the CPU 110. The CPU 110 receives a control signal input from the operation unit 113 or the communication unit 114 and controls the operation of each unit of the projection apparatus 100.

  The image input unit 120 is an interface that receives an image transmitted from an external device (not shown). The external device may be any device or medium that can output an image signal. Examples of the external device include, but are not limited to, a personal computer, a camera, a mobile phone, a smartphone, a game machine, a hard disk drive, a USB flash memory, and an SD card. The image input unit 120 outputs the received image data to the image processing unit 140. Further, the image input unit 120 can output an arbitrary OSD such as a GUI or a test pattern superimposed on the received image in accordance with an instruction from the CPU 110. Further, the image input unit 120 can output the received image to the RAM 111 in accordance with an instruction from the CPU 110.

  The light source control unit 130 is configured by, for example, a control microprocessor, and performs on / off control and light amount control of the light source 160. The light source control unit 130 does not need to be a dedicated microprocessor, and may be configured to function as the light source control unit 130 by the CPU 110 executing a program stored in the ROM 112, for example. The light source 160 outputs light for projecting an image on a screen (not shown). For example, a halogen lamp, a xenon lamp, a high-pressure mercury lamp, a laser, an LED, a phosphor, or a combination thereof. There may be. The color separation unit 165 includes, for example, a dichroic mirror or a prism, and separates light emitted from the light source 160 into red (R), green (G), and blue (B). In addition, when using LED corresponding to each color as the light source 160, the color separation part 165 is unnecessary.

  The image processing unit 140 includes, for example, a microprocessor, and performs predetermined image processing on the image signal acquired from the image input unit 120 and transmits the image signal to the light modulation control unit 150. The light modulation control unit 150 controls the voltage applied to each pixel of the light modulation elements 170R, 170G, and 170B based on the image signal acquired from the image processing unit 140, and the light of the light modulation elements 170R, 170G, and 170B. Control the modulation rate. The light modulation element 170R is a light modulation element corresponding to red, and controls the light modulation rate of red light that is separated and output by the color separation unit 165. The light modulation element 170G is a light modulation element corresponding to green, and controls the light modulation rate of the green light that is separated and output by the color separation unit 165. The light modulation element 170B is a light modulation element corresponding to blue, and controls the light modulation rate of the blue light separated and output by the color separation unit 165. The color synthesizing unit 180 includes a dichroic mirror, a prism, or the like, and synthesizes red (R), green (G), and blue (B) light modulated by the light modulation elements 170R, 170G, and 170B. . In the following description, when the light modulation elements 170R, 170G, and 170B are not distinguished, they are referred to as “light modulation elements 170”.

  The shift control unit 195 controls the attitude of the pixel shift element 190 by changing the voltage or current applied to the pixel shift element 190 in synchronization with the timing when the light modulation control unit 150 drives the light modulation element 170. . As a result, the optical path of the combined light from the color combining unit 180 can be shifted.

  FIG. 2 is a diagram for explaining the principle by which the pixel shift element 190 for performing pixel shift by the parallel plate method shifts the optical path in the vertical direction. In FIG. 2, in order to clarify the positional relationship of the optical path when the attitude of the pixel shift element 190 changes, different attitudes of the pixel shift element 190 are shown on the left and right on the common optical path.

  The pixel shift element 190 has a rectangular plate shape (rectangular plate shape), and includes an optical member 200 having a refractive index with respect to air of 1 or more and having transparency (translucency). The optical member 200 is arranged so that light in the entire region of the combined light (incident light) from the color combining unit 180 is transmitted through the optical member 200. The optical member 200 is desirably made of a material having a high transmittance. Specifically, the transmittance is desirably 80% or more, and more desirably 90% or more.

  In the pixel shift in the parallel plate method, the optical path is shifted by controlling the angle of the optical member 200 with respect to the incident light for each frame. The posture of the optical member 200 when the surface (incident surface) on which the combined light output from the color combining unit 180 in the optical member 200 is incident as incident light is orthogonal to the traveling direction of the incident light is referred to as a basic posture. The angle of the optical member 200 is set to 0 °.

The left side of FIG. 2 represents the relationship between the attitude of the optical member 200 with respect to the first frame image and the optical paths of incident light and output light. Details of the first frame image will be described later. For the first frame image, the optical member 200 is rotated counterclockwise, and the angle of the optical member 200 is set to −θ _S. Here, the rotation angle when the optical member 200 is rotated in the counterclockwise direction assumes a negative value, and therefore 'θ _S ' is a positive value. Then, the light incident on the optical member 200 is output to the projection optical system 183 after being shifted upward from the optical path of the incident light due to refraction as illustrated.

The right side of FIG. 2 represents the relationship between the attitude of the optical member 200 in the second frame image and the optical paths of the incident light and the output light. Details of the second frame image will be described later. For the second frame image, rotate the optical member 200 in the clockwise direction, the angle of the optical member 200 + theta and _S. Here, it is assumed that the rotation angle when the optical member 200 is rotated in the clockwise direction takes a positive value. Then, the light incident on the optical member 200 is output with the optical path shifted in the downward direction, which is the opposite direction to the first frame image, as illustrated. Therefore, the angle θ _S is designed so that the output light of the first frame image and the output light of the second frame image are shifted by ½ pixel with respect to the pixel pitch of the light modulation elements 170R, 170G, and 170B. Be controlled.

  Note that the principle by which the pixel shift element 190 shifts the optical path in the horizontal direction is the same as the principle by which the pixel shift element 190 shifts the optical path in the vertical direction as described above, and a description thereof will be omitted. The driving method of the optical member 200 is not limited. For example, the pixel shift element 190 includes a permanent magnet and a coil in addition to the optical member 200, and the shift control unit 195 controls the current flowing through the coil to control the optical member. 200 may be configured to be driven. Further, the pixel shift element 190 may have a piezoelectric element in the optical member 200, and the shift control unit 195 may be configured to drive the optical member 200 by controlling the voltage applied to the piezoelectric element.

  The optical system control unit 185 includes a control microprocessor and controls the projection optical system 183. The optical system control unit 185 does not need to be a dedicated microprocessor, and may be configured to function as the optical system control unit 185 by the CPU 110 executing a program stored in the ROM 112, for example. The projection optical system 183 includes a plurality of lenses and lens driving actuators, and projects the light transmitted through the pixel shift element 190 onto the screen. Enlargement and reduction of the projected image, focus adjustment, and the like can be performed by driving the lens.

  Next, the configuration of the image processing unit 140 will be described. FIG. 3 is a block diagram illustrating a configuration of the image processing unit 140. The image processing unit 140 acquires the input image IMG from the image input unit 120, generates an output image by performing processing described below in the image processing unit 140, and outputs the output image to the light modulation control unit 150.

  The image processing unit 140 includes an image generation unit 341, a first image memory 342, a second image memory 344, a position correction unit 343, a first correction table 345, a second correction table 346, and a selector 347. Each unit constituting the image processing unit 140 is connected to the CPU 110 via a bus 199. In the following description, when referring to each table or both tables without distinguishing between the first correction table 345 and the second correction table 346, the name “correction table” is simply used.

  The image generation unit 341 writes the input image IMG into the first image memory 342, and generates a first frame image DIV_A and a second frame image DIV_B that are reduced images for pixel shift display. The image generation unit 341 outputs the first frame image DIV_A and the second frame image DIV_B at a double speed of the input signal. For example, when the input frequency is 60 Hz (60 FPS), the first frame image DIV_A and the second frame image DIV_B are output at 120 Hz (120 FPS). Further, the image generation unit 341 outputs a synchronization signal for identifying whether the output image is the first frame image DIV_A or the second frame image DIV_B at the same timing.

  Here, a method of generating the first frame image DIV_A and the second frame image DIV_B will be described. FIG. 4 shows a projection position relationship on the projection plane between the first frame image DIV_A and the second frame image DIV_B. A square with numbers such as (0, 0) and (3, 3) represents one pixel at the projection position in the first frame image, and an aggregate of these squares becomes the first frame image DIV_A. . On the other hand, the hatched rectangle represents one pixel at the projection position in the second frame image, and an aggregate of these rectangles becomes the second frame image DIV_B. The first frame image DIV_A and the second frame image DIV_B are shifted by ½ pixel in each of the horizontal and vertical directions as a result of shifting the optical path by the pixel shift element 190 as shown in FIG. Projected to the selected position.

  FIG. 5 is a diagram illustrating the sampling phases of the first frame image DIV_A and the second frame image DIV_B with respect to the pixel arrangement of the input image. The image generation unit 341 samples pixel data in which both horizontal and vertical coordinates of the input image IMG are even numbers from the first image memory 342 and outputs the sampled pixel data as a first frame image DIV_A. Subsequently, the image generation unit 341 samples pixel data in which the horizontal and vertical coordinates of the input image IMG are both odd numbers from the first image memory 342 and outputs the sampled pixel data as a second frame image DIV_B.

  Returning to the description of FIG. The position correction unit 343 writes the first frame image DIV_A and the second frame image DIV_B acquired from the image generation unit 341 in the second image memory 344. Then, the position correction unit 343 reads the first frame image DIV_A and the second frame image DIV_B from the second image memory 344 and performs position correction based on the correction data stored in the correction table. The position correction unit 343 outputs the image after position correction to the light modulation control unit 150 as an output image IMG_D.

  Here, details of the position correction operation performed by the position correction unit 343 will be described. In the following description, an image output from the image generation unit 341 and input to the position correction unit 343 is referred to as a pre-correction image IMG_S. In the present embodiment, the pre-correction image IMG_S is specifically a first frame image DIV_A and a second frame image DIV_B. The position correction unit 343 calculates, for each pixel of the output image IMG_D, a reference pixel coordinate indicating which coordinate pixel of the pre-correction image IMG_S should be referred to, and refers to the pre-correction image IMG_S based on the calculated coordinates. The output image IMG_D is generated and output to the light modulation control unit 150. In the present embodiment, specifically, the output image IMG_D is an image obtained by correcting the position of each of the first frame image DIV_A and the second frame image DIV_B.

  The correction data used for calculation of the reference pixel coordinates is stored in each of the first correction table 345 and the second correction table 346. The position correction unit 343 corrects the position of the pre-correction image IMG_S based on correction data output from one of the first correction table 345 and the second correction table 346 selected by the selector 347. Details of the operation of the selector 347 will be described later.

  FIG. 6A is a diagram for explaining an example of data stored in the first correction table 345. FIG. 6B is a diagram for explaining an example of data stored in the second correction table 346. Each correction table uses the X and Y coordinates of the output image IMG_D as indexes, and stores correction data at the intersections. The correction data represents the coordinates of the pre-correction image IMG_S to be referred to at each intersection in the (X, Y) format. Each index of the X coordinate and the Y coordinate for the output image IMG_D in the first correction table 345 and the second correction table 346 is set at a predetermined interval. Here, both the X coordinate and the Y coordinate are corrected at an interval of 10 pixels. Holds data. For coordinates that do not exist in the index, reference pixel coordinates can be obtained by linear interpolation calculation, and details of the interpolation calculation will be described later with reference to FIG.

  For example, data (10, 10) is stored as correction data at the position where the coordinates (X, Y) of the output image IMG_D in FIG. 6A are (10, 10). This means that the gradation value is output with reference to the pixel at the coordinates (10, 10) of the pre-correction image IMG_S at the coordinates (10, 10) of the output image IMG_D. Therefore, the position correction unit 343 referring to the first correction table 345 outputs the pre-correction image IMG_S and the output image IMG_D as they are with the same coordinates. That is, here, the first correction table 345 stores correction data when position correction is not performed.

  On the other hand, the second correction table 346 of FIG. 6B stores correction data for performing partial position correction. Data (5, 5) is stored as correction data at the position where the coordinates (X, Y) of the output image IMG_D are (10, 10). This means that the gradation value is output with reference to the pixel at the coordinates (5, 5) of the pre-correction image IMG_S at the coordinates (10, 10) of the output image IMG_D.

  FIG. 7 is a diagram schematically illustrating position correction according to the correction data in FIG. Pixel data at the position of the coordinates (5, 5) of the pre-correction image IMG_S is output as pixel data of the coordinates (10, 10) of the output image IMG_D whose position has been corrected. Accordingly, the position of the pixel at the coordinates (5, 5) of the pre-correction image IMG_S is corrected by 5 pixels in each of the horizontal and vertical directions.

  Next, coordinate interpolation calculation when the position correction unit 343 performs position correction will be described. FIG. 8 is a schematic diagram illustrating coordinate interpolation calculation in the case of position correction. FIG. 8A is a diagram illustrating a positional relationship between coordinates obtained by interpolation calculation and an index of a correction table used for interpolation calculation. A white point represents coordinates obtained by interpolation calculation, and a black point represents an index of a correction table used for interpolation calculation. Here, the case of obtaining the X coordinate x (u ′, v ′) and Y coordinate y (u ′, v ′) of the reference pixel in the pre-correction image IMG_S of the coordinate (u ′, v ′) of the output image IMG_D. For example, The interpolation calculation is performed using four correction data around the coordinates (u ′, v ′) of the output image to be obtained. For this purpose, among the X coordinate indexes of the correction table, the maximum index that is smaller than “u ′” is “u”, and the “largest index that is larger than u ′ and minimum” is “u + d”. Further, among the Y coordinate indices of the correction table, the maximum index is smaller than “v ′”, the larger index is larger than “v”, “v ′”, and the smallest index is “v + d”. Then, interpolation calculation is performed using the four correction data whose correction table indexes are (u, v), (u + d, v), (u, v + d), and (u + d, v + d). Note that “d” is the index interval. For example, in the case of the correction table shown in FIG. 6, d = 10.

  In the coordinate interpolation calculation, first, X coordinate data x (u, v) stored in the coordinate index (u, v) of the correction table and X coordinate data x (u) stored in the coordinate index (u + d, v). Reference is made to u + d, v). Then, the X coordinate x (u ′, v) of the reference pixel in the pre-correction image IMG_S of the coordinate (u ′, v) of the output image IMG_D is obtained by interpolation using the following equation 1. Further, the X coordinate x (u ′, v + d) of the reference destination pixel in the pre-correction image IMG_S of the coordinate (u ′, v + d) of the output image IMG_D is obtained by the following equation 2. Further, the X coordinate x (u ′, v ′) of the reference pixel in the pre-correction image IMG_S of the coordinates (u ′, v ′) of the output image IMG_D is obtained by the following Equation 3. Similarly to these, the Y coordinate y (u ′, v ′) of the reference pixel in the pre-correction image IMG_S of the coordinate (u ′, v ′) of the output image IMG_D is obtained by the following equations 4-6. Thus, the pixel coordinates (x (u ′, v ′), y (u ′, v ′)) of the reference pixel in the pre-correction image IMG_S of the coordinates (u ′, v ′) of the output image IMG_D can be obtained. .

  FIG. 8B is a schematic diagram in which the result of calculating the X coordinate x (u ′, v ′) and the Y coordinate Y (u ′, v ′) of the reference destination pixel in the pre-correction image IMG_S is mapped. In FIG. 8B, black dots represent coordinate data stored in the table, and white dots represent coordinate data calculated by interpolation. The position correction unit 343 calculates the reference pixel coordinates of the pre-correction image IMG_S in all the pixels of the output image IMG_D as described above.

  Subsequently, the position correction unit 343 refers to the gradation values of the four pixels around the reference pixel coordinates in the pre-correction image IMG_S, and calculates the output gradation value at the reference pixel coordinates, for example, by bilinear interpolation. Note that the gradation value interpolation method is not limited to bilinear interpolation, and a bicubic interpolation method or other interpolation methods may be used. The position correction unit 343 obtains gradation values for all pixels of the corrected image in the above-described procedure, and generates an output image IMG_D. Note that the position correction unit 343 may perform position correction separately for each of the three color components (R, G, B), or may perform position correction for the three colors together.

  Since the first correction table 345 and the second correction table 346 each hold correction data at a predetermined coordinate interval, different position correction amounts can be set for each region. Therefore, the position correction unit 343 can adjust the position for each region of the image. It is also possible to perform position correction for shifting the entire image by adding an offset of the same value to all correction data in the correction table.

  By operating the position correction unit 343 as described above, the pre-correction image IMG_S output from the image generation unit 341 can be moved by an arbitrary position correction amount for each predetermined region. Further, since the correction coordinates are calculated with the accuracy of a small number of pixels and the gradation value is interpolated from the surrounding pixels, the display position can be corrected with an accuracy of one pixel or less.

  The selector 347 operates in synchronization with the synchronization signal output from the image generation unit 341, and the first correction table 345 is sent to the position correction unit 343 at the timing when the first frame image DIV_A is output from the image generation unit 341. Output. Further, the selector 347 outputs the second correction table 346 to the position correction unit 343 at the timing when the second frame image DIV_B is output from the image generation unit 341.

  Next, when the projection position of the second frame image with respect to the projection position of the first frame image by the pixel shift element 190 deviates from ½ pixel which is an ideal shift amount, a configuration and a method for correcting the deviation Will be described.

FIGS. 9A to 9C are diagrams for explaining an example of the optical path shift by the pixel shift element 190. FIG. As described with reference to FIG. 2, the shift control unit 195 has the angle of the optical member 200 of −θ _S degrees when the first frame image is displayed, and the angle of the optical member 200 is + θ when the second frame image is displayed. _The pixel shift element 190 is driven so as to be _S degrees. However, it is not easy to precisely control the angle of the optical member 200, and an angle error may occur.

The angle of the optical member 200 is −θ _AV degrees as shown in FIG. 9A when the first frame image is displayed, and + θ _{BV as} shown in FIG. 9B when the second frame image is displayed. Suppose that it is time. Here, for convenience of explanation, no angle error occurs when the first frame image is displayed, and an angle error α (> 0) occurs when the second frame image is displayed, so that the optical member 200 is larger than + θ _S degrees. It is assumed that it is rotating clockwise. That is, it is assumed that “−θ _AV = −θ _S ” and “+ θ _BV > + θ _S (θ _BV −α = θ _S ,)”.

As shown in FIG. 9A, for the first frame image, the displacement amount of the output light with respect to the incident light (hereinafter referred to as “the displacement amount between the incident light and the output light”) is “D _AV ”. Further, as shown in FIG. 9B, for the second frame image, the amount of displacement between the incident light and the output light is 'D _BV '. Therefore, in the vertical direction and cause the shift amount GAP_ENC only _'D AV ₊ D _BV' between the output light of the output light and the second frame image of the first frame _{image, 'D AV + D BV>} 1/2 It's a pixel. Note that the reason why “D _AV + D _BV > ½ pixel” is obtained from the description relating to FIG. Thus, if the shift amount GAP_ENC by the pixel shift element 190 is larger than the ideal ½ pixel, the effect of increasing the resolution cannot be obtained.

  FIG. 9C is a schematic diagram showing a state in which a ½ pixel shift is realized by causing the position-corrected second frame image to enter the optical member 200. The CPU 110 writes correction data for correcting the incident position with respect to the optical member 200 upward by the position correction amount C2 in the second correction table 346. Since the selector 347 outputs the correction data of the second correction table 346 at the timing when the image generation unit 341 outputs the second frame image DIV_B, the position correction unit 343 refers to the second correction table 346 and sets the display position. to correct. As a result, an image is displayed on the light modulation element 170 upward by the position correction amount C2. As a result, as shown in FIG. 9C, the incident light from the color synthesizing unit 180 is shifted upward in the drawing by the position correction amount C <b> 2 and enters the optical member 200. As a result, the shift amount GAP_ENC from the output light of the first frame image to the emitted light of the second frame image becomes ½ pixel, and the resolution can be increased.

With reference to FIG. 9, the correction method of the shift amount GAP_ENC in the case where the shift amount GAP_ENC when the position correction of the second frame image is not performed is larger than ½ pixel which is an ideal shift amount has been described. On the other hand, when the shift amount GAP_ENC when the position correction of the second frame image is not performed is smaller than ½ pixel, the displacement amount D _BV between the input light and the output light in the second frame image is What is necessary is just to obtain | require a position correction amount so that it may become larger.

  The CPU 101 detects a parameter related to the shift amount of each frame image by the optical member 200, and acquires the position correction amount C2 based on this parameter. Specifically, the CPU 101 acquires a shift amount with respect to a predetermined shift amount (1/2 pixel) of the shift amount GAP_ENC when the position correction of the frame image is not performed as a parameter. The CPU 101 controls each functional block of the projection apparatus 100 so as to project and display a test pattern that can identify the deviation amount. Then, the CPU 101 shift amount is acquired based on a captured image obtained by capturing the projected image with an imaging device (camera) (not shown). Then, the CPU 101 determines the position correction amount C2 based on the acquired deviation amount. The test pattern displayed in this case may be any pattern as long as the deviation amount can be confirmed. For example, a cross hatch or the like can be used. Further, a CZP (Circular Zone Plate) image may be displayed, and the position correction amount C2 that can reproduce the highest frequency component may be determined by adjustment by the user. Alternatively, the position correction amount may be set according to an instruction (input value) from the user. In the above description, the example of correcting the vertical shift is described, but the horizontal shift can be corrected using the same method.

  The shift amount GAP_ENC may be different for each position (region) on the image projection plane due to an in-plane difference in the thickness of the optical member 200, an in-plane difference in optical characteristics, a deflection of the optical member 200, or the like. . However, even in such a case, the position correction unit 343 is configured to be able to perform different position corrections for each area of the image as described above. Therefore, the shift amount GAP_ENC is set to 1 over the entire area of the image projection plane. / 2 pixels can be corrected.

  In the description with reference to FIG. 9, the projection position of the second frame image is corrected based on the projection position of the first frame image. However, the present invention is not limited to this, and by writing a predetermined position correction amount in the first correction table 345 when the first frame image is projected and displayed, it is possible to perform the same correction as that for correcting the shift in the second frame image. That is, even when an angle error occurs when the optical member 200 is driven to project and display the first frame image, it is possible to set the position correction amount and reduce the shift amount. The resolution of the projected image can be increased.

As described above, in the first embodiment, when the pixel shift display is performed, the shift amount GAP_ENC is set to the ideal in consideration of the displacement amounts D _AV and D _BV between the incident light / output light of the frame image by the pixel shift element 190. It corrected to a typical 1/2 pixel. Thereby, the resolution can be increased. At this time, the correction of the shift amount GAP_ENC is realized not by adjusting the pixel shift element 190 but by correcting the image data. Therefore, the cost can be reduced more than the method of correcting the shift amount GAP_ENC by increasing the drive control of the pixel shift element 190, the processing accuracy of the optical member 200, and the like. It is possible to easily correct a deviation caused by deterioration with time after shipment of the product (projection apparatus).

Second Embodiment
In the second embodiment, a projector that corrects an image projection position (shift amount GAP_ENC) by obtaining a displacement amount between incident light and output light of a frame image based on a result of detecting an angle of the optical member 200 will be described. .

  The projection apparatus according to the second embodiment is different from the projection apparatus 100 according to the first embodiment in that the shift control unit 195 includes an angle detection unit of the optical member 200, but the other configurations are the same. A description of the common configuration is omitted. The angle detection method of the optical member 200 is not limited, and can be detected using a known technique, for example, with a rotary encoder, an acceleration sensor, or the like. The CPU 110 calculates a position correction amount to be written in the first correction table 345 and the second correction table 346 based on the angle of the optical member 200 detected by the shift control unit 195.

FIG. 10 is a schematic diagram for explaining a method for calculating the displacement amount D between the incident light and the output light based on the angle of the optical member 200. The incident angle of incident light is “θ ₁ ”, the refraction angle of light within the optical member 200 is “δ ₁ ”, the thickness of the optical member 200 is “t”, and the refractive index of the optical member 200 with respect to air is “n”. To do. Here, the angle formed between the incident light and the incident surface of the optical member 200 (= incident angle θ ₁ ), and the angle formed between the surface orthogonal to the incident light and the incident surface of the optical member 200 (= angle θ of the optical member 200). Are equal. That is, the angle θ of the optical member 200 detected by the shift control unit 195 can be used as the incident angle θ ₁ . Therefore, the displacement amount D can be calculated by the following equation 7, and the CPU 110 calculates the displacement amount D using the following equation 7. The displacement amount D is positive in the lower direction in FIG. 10 and negative in the upper direction as in FIG. Further, it is assumed that the thickness t of the optical member 200 and the refractive index n of the optical member 200 with respect to the air are stored in the ROM 112 in advance.

The CPU 110 determines the position correction amount based on the calculated displacement amount D and the pixel pitch of the light modulation element 170 so that a 1/2 pixel shift is realized. For example, as shown in FIGS. 9A and 9B, the displacement amount in the first frame image when the position correction unit 343 does not perform correction is “D _AV ”, and the displacement amount in the second frame image is “ _Let D _BV 'and the pixel pitch of the light modulation element 170 be' P '. It is assumed that the pixel pitch P of the light modulation element 170 is stored in the ROM 112 in advance. In this case, the position correction amount may be determined so that the relationship D _AV −D _BV = P / 2 is satisfied. That is, if the position correction amount in the second frame image is “C2”, the position correction amount C2 is C2 = (P / 2) − | D _AV −D _BV | [mm] = (1/2) − | D _AV −D _BV | / P [pixel].

As a specific example, if the pixel pitch P of the light modulation element 170 is 10 μm, the ½ pixel is 5 μm. Therefore, if the difference between the displacement amounts D _AV and D _BV is 5 μm, a _½ pixel shift is performed. It can be said that it has been realized. When the displacement amount D _AV in the first frame image when the position correction unit 343 does not perform correction is −2 μm and the displacement amount D _BV in the second frame image is +4 μm, the position correction amount C2 is −0.1 pixel. It becomes. In this case, the CPU 110 can correct the shift amount GAP_ENC to ½ pixel by writing correction data for shifting the projection position of the second frame image by 0.1 pixel upward in the second correction table 346. .

  In general, the refractive index n of the optical member 200 with respect to air varies depending on the wavelength of incident light. Therefore, when the position correction unit 343 is configured to be able to perform different corrections for each color (RGB), the displacement amount D between the incident light and the output light is calculated with a refractive index corresponding to the wavelength. Is desirable. On the other hand, in order to suppress the calculation amount and the storage capacity, a refractive index of a representative wavelength may be used. Further, when the refractive index n changes depending on the temperature of the optical member 200, the temperature of the optical member 200 is configured to be detectable, and the displacement amount D between the incident light / output light is calculated according to the temperature of the optical member 200. You may do it. In that case, the temperature characteristic of the refractive index n of the optical member 200 is stored in advance in the ROM 112 so that the CPU 110 can refer to it.

  Furthermore, since the temperature of the optical member 200 is likely to increase as the amount of incident light increases, the position correction amount may be determined based on the input image IMG. For example, the CPU 110 may be configured to increase the position correction amount as the average luminance (APL) of the input image IMG increases. Further, the position correction amount may be determined based on the feature amount such as the average luminance of the first frame image DIV_A or the second frame image DIV_B.

  As described above, in the second embodiment, the angle of the optical member 200 is detected, and the displacement amount D between the incident light / output light is calculated based on the detected angle to realize a 1/2 pixel shift. A position correction amount is obtained. Thereby, the effect similar to 1st Embodiment can be acquired.

<Third Embodiment>
In the third embodiment, a projection apparatus that corrects the image projection position (shift amount GAP_ENC) according to the cumulative number of times the shift control unit 195 has driven the pixel shift element 190 will be described.

  The projection apparatus according to the third embodiment is different from the projection apparatus 100 according to the first embodiment in that the shift control unit 195 includes a unit that counts the cumulative number of driving times of the pixel shift element 190, but the other configurations are the same. Therefore, description of the common configuration is omitted. The cumulative number of times of driving refers to the total number of times that the pixel shift element 190 has performed a shift operation after shipment of the projection device as a product. The CPU 110 stores the cumulative number of driving times counted by the shift control unit 195 in the RAM 111. Note that the cumulative drive count stored in the RAM 111 is maintained even when the power of the projection apparatus is turned off. The CPU 110 calculates a position correction amount corresponding to the cumulative number of driving times counted by the shift control unit 195 and writes it in the first correction table 345 and the second correction table 346.

  FIG. 11A is a diagram illustrating an example of the posture during the shift operation of the optical member 200 when the cumulative number of driving times of the pixel shift element 190 is small. FIG. 11B is a diagram illustrating an example of the posture during the shift operation of the optical member 200 when the cumulative number of driving times of the pixel shift element 190 is large.

  The pixel shift element 190 has an abutting portion 1101. The maximum angle of the optical member 200 is defined by the height of the abutting portion 1101. In the state of FIG. 11A, the height of the abutting portion 1101 is “h”, whereas in the state of FIG. Due to the change, the height of the abutting portion 1101 is ht (h> ht) smaller than the height h. Therefore, the maximum angle of the optical member 200 is increased from “θ” to “θ + β” in FIG. 11A, and accordingly, the amount of displacement between the incident light and the output light is changed from “D” to “Dt”. (Dt> D) ′.

  In the third embodiment, data indicating the relationship between the cumulative number of driving times and the amount of displacement is stored in the ROM 112 in a predetermined format such as a table or a mathematical expression. The CPU 110 obtains a displacement amount corresponding to the counted cumulative driving number from the data stored in the ROM 112 according to the cumulative driving number counted by the shift control unit 195. Then, the CPU 110 calculates the position correction amounts of the first frame image and the second frame image for realizing a ½ pixel shift from the obtained displacement amount, and stores them in the first correction table 345 and the second correction table 346. Write. The position correction unit 343 performs correction with reference to the correction data written in the first correction table 345 and the second correction table 346. Accordingly, a 1/2 pixel shift is realized by correcting the increase in the amount of displacement between the incident light and the output light caused by the height of the abutting portion 1101 being lowered in accordance with the increase in the cumulative number of driving times. Can do. Thus, the third embodiment can achieve the same effects as those of the first embodiment.

<Fourth embodiment>
In the fourth embodiment, a description will be given of a projection apparatus that increases resolution by performing pixel shift in four directions. The projection apparatus according to the fourth embodiment differs from that of the projection apparatus 100 according to the first embodiment in the configuration or operation of the image processing unit, the pixel shift element, and the shift control unit. The same. Hereinafter, the projection apparatus according to the fourth embodiment will be described with a focus on differences from the projection apparatus 100, and description of the configuration common to the projection apparatus 100 will be omitted.

  FIG. 12 is a block diagram showing the configuration of the image processing unit 1200 of the projection apparatus according to the fourth embodiment. Among the constituent elements of the image processing unit 1200, those having the same functions as those of the constituent elements of the image processing unit 140 of the projection apparatus 100 are denoted by the same reference numerals, and a common description is omitted as appropriate. The image processing unit 1200 is different from the image processing unit 140 in that it has four correction tables that the position correction unit 343 refers to. The four correction tables are a first correction table 1201, a second correction table 1202, a third correction table 1203, and a fourth correction table 1204. These correction tables are equivalent to the correction tables described in the first embodiment. Is.

  The image generation unit 341 of the image processing unit 1200 writes the input image IMG in the first image memory 342. Then, the image generation unit 341 generates four frame images for pixel shift display, that is, a first frame image DIV_A, a second frame image DIV_B, a third frame image DIV_C, and a fourth frame image DIV_D. Then, the image generation unit 341 outputs the generated first frame image DIV_A, second frame image DIV_B, third frame image DIV_C, and fourth frame image DIV_D to the position correction unit 343 at a quadruple speed. For example, when the input frequency is 60 Hz (60 FPS), the output frequency is 240 Hz (240 FPS). The image generation unit 341 outputs a synchronization signal that can identify which of the first frame image DIV_A, the second frame image DIV_B, the third frame image DIV_C, and the fourth frame image DIV_D. .

  The pixel shift element 190 performs pixel shift in four directions. FIG. 13 is a diagram for explaining the projection positions of four frame images when pixel shift is performed in four directions. The resolution of an image projected and displayed without correcting the four frame images by the position correction unit 343 is increased. It shows the ideal projection position that can be done. As shown in the upper left of FIG. 13, the first frame image DIV_A is projected on the projection plane. Subsequently, as shown in the upper right of FIG. 13, the second frame image DIV_B is projected at a position shifted to the right by ½ pixel from the first frame image DIV_A. Next, as shown in the lower right of FIG. 13, the third frame image DIV_C is projected to a position shifted by ½ pixel below the second frame image DIV_B. Finally, as shown in the lower left of FIG. 13, the fourth frame image DIV_D is projected to a position shifted to the left by ½ pixel from the third frame image DIV_C. Thereafter, the process returns to the projection of the first frame image DIV_A.

  FIG. 14 is a schematic diagram illustrating a method for generating the first frame image DIV_A, the second frame image DIV_B, the third frame image DIV_C, and the fourth frame image DIV_D from the input image IMG. The image generation unit 341 generates pixel image data DIV_A from the first image memory 342 by sampling pixel data having an even horizontal coordinate and an even vertical coordinate of the input image IMG. The image generation unit 341 samples pixel data of the input image IMG whose horizontal coordinates are odd and whose vertical coordinates are even from the first image memory 342, and generates the second frame image DIV_B. The image generation unit 341 generates pixel image data DIV_C from the first image memory 342 by sampling pixel data having an odd horizontal coordinate and an odd vertical coordinate of the input image IMG. The image generation unit 341 generates pixel image data DIV_D from the first image memory 342 by sampling pixel data of the input image IMG whose horizontal coordinates are even and whose vertical coordinates are odd.

  As shown in FIG. 13, by projecting the generated first frame image DIV_A, second frame image DIV_B, third frame image DIV_C, and fourth frame image DIV_D in four directions on the projection plane, High resolution can be achieved. However, the pixel shift element 190 is set so that the shift amounts of the second frame image DIV_B, the third frame image DIV_C, and the fourth frame image DIV_D with respect to the first frame image DIV_A are ideal ½ pixels during projection. It is not easy to drive. Therefore, the image processing unit 1200 operates as described below to correct the shift when the shift amount GAP_ENC due to the driving of the pixel shift element 190 is shifted from 1/2 pixel, and Realize pixel shift.

  That is, the selector 347 operates in synchronization with the synchronization signal output from the image generation unit 341, and the first correction table 1201 is sent to the position correction unit 343 at the timing when the first frame image DIV_A is output from the image generation unit 341. Output. Similarly, the selector 347 outputs the second correction table 1202 to the position correction unit 343 at the timing when the second frame image DIV_B is output from the image generation unit 341. The selector 347 outputs the third correction table 1203 to the position correction unit 343 at the timing when the third frame image DIV_C is output from the image generation unit 341. The selector 347 outputs the fourth correction table 1204 to the position correction unit 343 at the timing when the fourth frame image DIV_D is output from the image generation unit 341.

  Thus, in the fourth embodiment, the position correction unit 343 switches the correction table that is referred to for each of the four frame images. Thereby, for each of the four frame images, it is possible to correct the displacement amount between the incident light and the output light according to the driving characteristics of the pixel shift element 190, thereby realizing a 1/2 pixel shift, The same effect as that of the first embodiment can be obtained.

<Fifth Embodiment>
In the fifth embodiment, a configuration in which the position correction amount is changed according to the temperature of the pixel shift element will be described. Note that the configuration and operation of each unit other than the shift control unit, the pixel shift element, and the CPU in the projection device according to the fifth embodiment are the same as those of the projection device according to the first embodiment, and thus description thereof is omitted. Hereinafter, a characteristic configuration of the fifth embodiment will be described. The shift control unit and the CPU will be described using the same reference numerals as those described in the first embodiment.

  FIG. 15 is a side view illustrating a schematic configuration of a pixel shift element 1500 included in the projection apparatus according to the fifth embodiment. The pixel shift element 1500 is configured by bonding a liquid crystal panel 1510 and a birefringent element 1520 together. Light from the color composition unit 180 enters the liquid crystal panel 1510, and the linear polarization direction in the liquid crystal panel 1510 is switched by the shift control unit. The birefringent element 1520 has birefringence characteristics and spatially shifts the optical path of output light according to the linear polarization direction.

  A shift control unit 195 (not shown) that controls driving of the pixel shift element 1500 controls the optical path of the frame image by changing the voltage applied to the liquid crystal panel 1510. Further, the shift control unit 195 detects the temperature of the pixel shift element 1500. As the temperature detecting means, a temperature sensor such as a thermocouple, a thermistor, a resistance temperature detector, or the like can be used, but any configuration may be used as long as the temperature can be detected.

  Since the liquid crystal panel 1510 and the birefringent element 1520 have temperature characteristics, and the amount of displacement between incident light and output light may change depending on the temperature, the shift amount GAP_ENC may deviate from ½ pixel. is there. Therefore, the position correction unit 343 corrects the frame image output from the image generation unit 341 in accordance with the temperature of the pixel shift element 1500. Specifically, first, the CPU 110 (not shown) acquires the temperature of the pixel shift element 1500 from the shift control unit 195. Subsequently, the CPU 110 calculates a position correction amount by referring to the temperature characteristics of the liquid crystal panel 1510 and the birefringent element 1520 stored in advance in the ROM 112, and the calculated position correction amount is used as the first correction table 345 and the second correction table. Write to 346. For example, when a birefringent element 1520 whose refractive index increases as the temperature rises is used, correction data is stored in the ROM 112 so that a larger position correction amount is calculated as the pixel shift element 1500 becomes higher in temperature. The Conversely, when a birefringent element 1520 having a refractive index that decreases as the temperature rises is used, correction data is stored in the ROM 112 such that a smaller position correction amount is calculated as the pixel shift element 1500 becomes higher in temperature. Is done.

  As described above, in the fifth embodiment, the position correction unit 343 takes into account the change in the amount of displacement between the incident light and the output light accompanying the temperature change of the pixel shift element 1500, and the first correction table 345 and the second correction table. The frame image is projected using the position correction amount written in 346. Thus, a 1/2 pixel shift can be realized, and the same effect as that of the first embodiment can be obtained.

<Sixth Embodiment>
In the first to fifth embodiments, the configuration has been described in which the shift of the image projection position caused by the pixel shift element is corrected by correcting the image after generating the reduced image. On the other hand, in the sixth embodiment, the image to be projected is corrected by determining the reduced sampling phase when generating the reduced image according to the shift amount by the pixel shift element from the ideal image projection position. A configuration for realizing a 1/2 pixel shift will be described.

  In the first to fifth embodiments, when the position correction unit 343 generates the output image IMG_D, the interpolation process is executed twice for the input image IMG_S. In the sixth embodiment, the interpolation process for the input image IMG_S is performed. Can be completed once. The projection device according to the sixth embodiment is different from the projection device 100 according to the first embodiment in the configuration or operation of the image processing unit, the pixel shift element, and the shift control unit. The same as 100. Hereinafter, the projection apparatus according to the sixth embodiment will be described with a focus on differences from the projection apparatus 100, and the description of the configuration common to the projection apparatus 100 will be omitted.

  FIG. 16 is a block diagram illustrating a configuration of an image processing unit 1600 included in the projection apparatus according to the sixth embodiment. The image processing unit 1600 includes an encoding unit 1601, a phase calculation unit 1602, a first image generation unit 1603, a second image generation unit 1604, a selection unit 1605, and an image memory 1610. Each unit constituting the image processing unit 1600 is connected to the CPU 110 via the bus 199.

  The encoding unit 1601 acquires the angle θ of the optical member 200 constituting the pixel shift element 190, and performs conversion to the shift amount GAP_ENC. The definition of the angle θ is the same as that in the first embodiment (see FIGS. 9 and 10). Further, as described in the second embodiment, the angle θ can be detected using a known technique.

When acquiring the angle θ, two angles are acquired: the angle θ _AV of the optical member 200 corresponding to the first frame image in the vertical direction and the angle θ _BV of the optical member 200 corresponding to the second frame image. The relationship between the angle θ _AV , the angle θ _BV, and the shift amount GAP_ENC _V in the vertical direction is as described with reference to FIGS. Note that the angle θ _AH and the angle θ _BH in the horizontal direction can be acquired in the same manner as in the vertical direction.

A vertical displacement D _AV (see FIG. 9A) corresponding to the first frame image can be calculated by the following equation 8 according to the above equation 7. In the following Expression 8, 't' is the thickness of the optical member 200, 'θ _1AV ' is the incident angle of incident light, 'δ _1AV ' is the light refraction angle in the optical member 200, and 'n' is the optical member. The refractive index is 200 with respect to air, and the relationship 'θ _1AV = θ _AV ' holds. The vertical displacement amount D _BV (see FIG. 9B) for the second frame image can be obtained by substituting “incident angle θ _AV ” with “incident angle θ _BV ” in the following equation (8). The horizontal displacement amounts D _AH and D _BH for each of the first frame image and the second frame image can be calculated in the same manner as the displacement amounts D _AV and D _AH , respectively.

The horizontal shift amount GAP_ENC _H and the vertical shift amount GAP_ENC _V are calculated from the calculated displacement amounts D _AV , D _BV , D _AH , and D _{BH according} to FIG. 9C and the description in the second embodiment. It can be calculated by the following formula 9 and the following formula 10. Note that “PWID _H ” is the horizontal pixel pitch in the number of panel pixels, and “PWID _V ” is the vertical pixel pitch in the number of panel pixels. Dividing by the pixel pitch in the number of panel pixels as in Expressions 9 and 10 below is based on the shift amount GAP_ENC _{H with} respect to the shift amounts D _AH , D _BH , D _AV and D _BV calculated by the absolute value of the length. , GAP_ENC _V is calculated as a pixel unit value. The calculated shift amounts GAP_ENC _H and GAP_ENC _V are output to the phase calculation unit 1602.

Based on the shift amounts GAP_ENC _H and GAP_ENC _V calculated by the encoding unit 1601, the phase calculation unit 1602 sets a reduced sampling phase PHASE_A when the first image generation unit 1603 generates the first frame image DIV_A that is a reduced image. calculate. Similarly, the phase calculation unit 1602 calculates a reduced sampling phase PHASE_B when the second image generation unit 1604 generates the second frame image DIV_B that is a reduced image. Hereinafter, the reduced sampling phase PHASE_A is referred to as “sampling phase P _A ”, and the reduced sampling phase PHASE_B is referred to as “sampling phase P _B ”.

FIG. 17 is a diagram for explaining a method of calculating the reduced sampling phases P _A and P _B , showing the resolution corresponding to the input image IMG, and an image having a resolution twice the panel resolution is input. For example, if the panel resolution is FHD (1920 × 1080 pixels), the input image IMG is 4K (3840 × 2160 pixels).

The reduced sampling phases P _A and P _B are each composed of a horizontal component and a vertical component. Downsampling phase P _A is A smaller sampling phase of the first frame image DIV_A in Fig 5 and is calculated as the difference amount from the center of the pixel position horizontal and vertical coordinates are both "even". In FIG. 17, the pixel D1 is generated as the first frame image DIV_A. In the present embodiment, since the basis of the reduced sampling phase P _A, horizontal downsampling phase P _AH and vertical sampling phase P _AV are both zero (0). The reduced sampling phases P _AH and P _AV are output to the first image generation unit 1603.

On the other hand, the reduced sampling phase P _B is the reduced sampling phase of the second frame image DIV_B in FIG. 5, and thus is calculated as a difference amount from the center of the pixel position where the horizontal coordinate and the vertical coordinate are both “odd”. In FIG. 17, ideally, the pixel D4 is generated as a reduced image, but actually there are many cases where deviation from the ideal state occurs. Assuming that the horizontal shift amount in the ideal state is “ZM _H ”, the horizontal shift amount DIFF _H from the ideal state is obtained by DIFF _H = GAP_ENC _H −ZM _H. Similarly, assuming that the vertical shift amount in the ideal state is “ZM _V ”, the vertical shift amount DIFF _V from the ideal state is obtained by DIFF _V = GAP_ENC _V −ZM _V. Then, the horizontal reduced sampling phase P _BH used in the second image generation unit 1604 is obtained by P _BH = DIFF _H using the shift amount DIFF _H. Similarly, the reduced sampling phase P _{BV in the} vertical direction used in the second image generation unit 1604 is obtained by P _BV = DIFF _V using the shift amount DIFF _V. The calculated reduced sampling phases P _BH and P _BV in the horizontal direction are output to the second image generation unit 1604.

The first image generating unit 1603 writes the input image IMG to the image memory 1610, based on the reduced sampling phase _{P A} calculated by the phase calculating section 1602, and generates a first frame image DIV_A for pixel shift display. As described above, the first image generation unit 1603 outputs the pixel value of the pixel D1 as it is as the first frame image DIV_A. This is because the shift amount is absorbed by correcting with the second frame image DIV_B with the first frame image DIV_A as a reference. For this reason, the first frame image DIV_A is subjected to reduction processing at a predetermined ideal reduction sampling phase.

The second image generation unit 1604 writes the input image IMG into the image memory 1610, and generates a second frame image DIV_B for pixel shift display based on the reduced sampling phase P _B calculated by the phase calculation unit 1602. Here, a method for calculating the pixel value at the interpolation position P1 will be described in detail with reference to FIG. The interpolation pixel value OD at the interpolation position P1 is calculated by weighting and combining the pixel values of the pixels D4, D5, D6, and D7 with the reduced sampling phases P _BH and P _BV based on the distance from the interpolation position P1. Can be calculated. Note that 'D4 (ix_i, iy_i)' is the pixel value of the pixel D4, 'D5 (ix_i + 1, iy_i)' is the pixel value of the pixel D5, 'D6 (ix_i, iy_i + 1)' is the pixel value of the pixel D6, and 'D7 ( ix_i + 1, iy_i + 1) ′ is the pixel value of the pixel D7. The second image generation unit 1604 outputs the calculated interpolation pixel value OD for all the pixels as the second frame image DIV_B. Here, although an interpolation method using bilinear interpolation is illustrated, other interpolation methods such as a bicubic interpolation method may be used. When the bicubic interpolation method is used, the second frame image DIV_B with higher image quality can be generated.

  The selection unit 1605 selects the first frame image DIV_A and the second frame image DIV_B at the double speed of the input signal, and outputs the selected image to the light modulation control unit 150 as the output image IMG_D. For example, when the force frequency is 60 Hz, the first frame image DIV_A and the second frame image DIV_B are switched and output at 120 Hz. The selection unit 1605 outputs a synchronization signal for identifying whether the output image IMG_D is the first frame image DIV_A or the second frame image DIV_B to the shift control unit 195.

As described above, in the sixth embodiment, a 1/2 pixel shift is realized by detecting the angle of the optical member 200 and controlling the reduced sampling phase when generating a reduced image to correct the image projection position. Thereby, the resolution of the projected image can be increased. Note that the amount of deviation (that is, the correction amount) with respect to the desired shift amount differs for each position on the projection surface due to an in-plane difference in thickness of the optical member 200, an in-plane difference in optical characteristics, a deflection of the optical member 200, or the like. There is. Even in such a case, in the sixth embodiment, the encoding unit 1601 calculates a different shift amount GAP_ENC for each region, and the phase calculation unit 1602 calculates the reduced sampling phases P _A and P _B for each region. It is possible to generate a reduced image for each region. Thereby, a ½ pixel shift can be realized over the entire projection surface.

<Seventh embodiment>
In the seventh embodiment, a modification of the image processing unit 1600 described in the sixth embodiment will be described. In the sixth embodiment, the reduced sampling phase for generating the reduced image is determined according to the shift amount by the pixel shift element from the ideal image projection position, but in the seventh embodiment, in addition to the reduced sampling phase. A configuration for determining the filter coefficient will be described.

  FIG. 18 is a block diagram illustrating a configuration of an image processing unit 1800 included in the projection apparatus according to the seventh embodiment. The image processing unit 1800 is different from the image processing unit 1600 shown in FIG. 16 in that it includes a filter coefficient calculation unit 1801, but the other configuration is the same as the image processing unit 1600. Hereinafter, the image processing unit 1800 will be described with a focus on differences from the image processing unit 1600, and description of the configuration common to the image processing unit 1600 will be omitted.

  In the configuration of the image processing unit 1600, when the shift amount by the pixel shift element from the ideal image projection position increases, the time required for changing the posture of the pixel shift element 190 (time required for the rotation operation) increases, and the adjacent frame The amount of crosstalk in which the images are mixed increases. As a result, the image becomes blurred and the effect of increasing the resolution cannot be obtained. With respect to this problem, in the image processing unit 1800, when generating a reduced image, the filter coefficient calculation unit 1801 controls the filter coefficient according to the shift amount by the pixel shift element 190.

Based on the shift amount GAP_ENC of the pixel shift element 190 calculated by the encoding unit 1601, the filter coefficient calculation unit 1801 calculates a filter coefficient FIL _A when the first image generation unit 1603 performs interpolation processing. In the same manner, the filter coefficient calculation unit 1801 calculates a filter coefficient FIL _B when the second image generation unit 1604 performs the interpolation process. At that time, the filter coefficient calculation unit 1801 calculates the filter coefficients FIL _A and FIL _B so that the filter characteristics become steeper as the shift amount GAP_ENC increases.

  FIG. 19 is a diagram illustrating an example of filter coefficient characteristics when a reduced image is generated. FIG. 19A shows a general bicubic filter coefficient, and FIG. 19B shows a general nearest neighbor filter coefficient. When bicubic interpolation is performed, generally, interpolation is performed using neighboring neighboring pixel values, so the edges of the image tend to be slightly blurred, and the peak luminance tends to decrease due to the filter shape. is there. As a result, when one pixel is lit, the peak luminance tends to decrease and the edge tends to be blurred. However, since neighboring neighboring pixels are used when generating a reduced image, there is an advantage that information loss is reduced with respect to the input image IMG.

  On the other hand, when nearest neighbor interpolation is performed, the filter characteristics are steeper than those of the bicubic method, so that edge information tends to remain even after interpolation. As a result, the edges are less likely to blur, and there is a tendency for the luminance to be reduced less than in the bicubic method. However, since adjacent pixels are not referred to when the reduced image is generated, there is a tendency for information to be missing from the input image IMG.

  By optimizing the filter coefficient based on the shift amount GAP_ENC by the pixel shift element 190, it is possible to suppress the loss of information due to the reduction process while appropriately suppressing the occurrence of blurring in the reduced image. In other words, it is possible to reduce the blurring of the projected image that occurs due to an increase in the shift amount by the pixel shift element 190.

The first image generating unit 1603 uses the input image IMG, downsampling calculated by the phase calculating section 1602 phase _{P A} and the filter coefficients FIL _A calculated by the filter coefficient calculation unit 1801, generating a first frame image DIV_A To do. Similarly, the second image generation unit 1604 uses the input image IMG, the reduced sampling phase P _B calculated by the phase calculation unit 1602 and the filter coefficient FIL _B calculated by the filter coefficient calculation unit 1801 to use the second frame image. DIV_B is generated. At that time, the control of the reduced sampling phases P _A and P _B is performed in the same manner as in the sixth embodiment. Further, for example, bicubic interpolation can be used for coordinate interpolation.

  As described above, in the seventh embodiment, the filter coefficient for generating a reduced image is controlled according to the shift amount GAP_ENC of the pixel shift element 190. Thereby, it is possible to increase the resolution by realizing a 1/2 pixel shift while suppressing the occurrence of blurring in the projected image.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 100 Projector 140,1200,1600 Image processing part 150 Light modulation control part 170 Light modulation element 190 Pixel shift element 195 Shift control part 200 Optical member 341 Image generation part 343 Position correction part 345 1st correction table 346 2nd correction table 347 Selector 1500 Pixel shift element 1602 Phase calculation unit 1605 Selection unit 1801 Filter coefficient calculation unit

Claims (15)

Generating means for generating a plurality of images from an input image;
Modulation means for modulating light from a light source according to the plurality of images;
Shift means for shifting light output from the modulation means in a predetermined direction;
Control means for controlling the shift means;
Detecting means for detecting a parameter relating to a shift amount by the shifting means;
And a correction unit that corrects at least one of the plurality of images based on the parameter.   The projection apparatus according to claim 1, wherein the correction unit corrects at least one of the plurality of images so that the shift amount approaches a predetermined shift amount. Generating means for sampling an input image to generate a plurality of images;
Modulation means for modulating light from a light source according to the plurality of images;
Shift means for shifting light output from the modulation means in a predetermined direction;
Control means for controlling the shift means;
Detecting means for detecting a parameter relating to a shift amount by the shift means,
The projecting device generates the plurality of images by sampling the input image with a phase based on the parameter.   The projection apparatus according to claim 3, wherein the generation unit further corrects a filter coefficient when generating the plurality of images based on the parameter.   5. The projection apparatus according to claim 3, wherein the generation unit determines a phase for generating the plurality of images so that the shift amount approaches a predetermined shift amount. 6.   The projection apparatus according to claim 2, wherein the parameter is a shift amount of the shift amount with respect to the predetermined shift amount. The shift means includes an optical member that transmits light,
The control means controls the optical member so as to change the incident angle of the light output from the modulation means to the optical member for each of the plurality of images, thereby predetermining the light output from the modulation means. The projection apparatus according to claim 1, wherein the projection apparatus is shifted in the direction of.   The detection means is an incident angle of the light output from the modulation means with respect to the optical member, or an angle formed by a surface perpendicular to the traveling direction of the light output from the modulation means and the incident surface of the optical member, The projection apparatus according to claim 7, wherein the parameter is detected based on the detected angle.   The projection device according to claim 7, wherein the detection unit detects a temperature of the optical member and detects the parameter based on the detected temperature. The shift means includes a liquid crystal panel and an optical member having birefringence characteristics,
8. The control device according to claim 1, wherein the control unit shifts light output from the modulation unit in a predetermined direction by controlling a voltage applied to the liquid crystal panel. 9. Projection device. A counting means for counting the cumulative number of driving times of the shift means;
The projection apparatus according to claim 1, wherein the detection unit detects the parameter based on the cumulative number of times of driving. A control method for a projection apparatus, comprising: a light source; a modulation element that modulates light emitted from the light source; and an optical member that shifts light output from the modulation element in a predetermined direction.
A generation step of generating a plurality of images from the input image;
A correction step of correcting at least one of the plurality of images;
A modulation control step for controlling the modulation element to modulate light emitted from the light source based on the plurality of images;
A shift control step for controlling the driving of the optical member so as to shift the light output from the modulation element in the predetermined direction;
A detection step of detecting a parameter relating to a shift amount by the optical member;
Have
The method of controlling a projection apparatus, wherein the correcting step corrects at least one of the plurality of images based on the parameter. A control method for a projection apparatus, comprising: a light source; a modulation element that modulates light emitted from the light source; and an optical member that shifts light output from the modulation element in a predetermined direction.
A generation step of sampling the input image to generate a plurality of images;
A correction step of correcting at least one of the plurality of images;
A modulation control step for controlling the modulation element to modulate light emitted from the light source based on the plurality of images;
A shift control step for controlling the driving of the optical member so as to shift the light output from the modulation element in the predetermined direction;
A detection step of detecting a parameter relating to a shift amount by the optical member;
Have
The method for controlling a projection device, wherein the generating step samples the input image at a phase based on the parameter to generate the plurality of images.   The program for functioning a computer as each means of the projection apparatus of any one of Claims 1 thru | or 11. A storage medium for storing a program for causing a computer to function as each unit of the projection apparatus according to claim 1.

Images