JP5509904B2 - projector - Google Patents

Description

  The present invention relates to a technology of a projector, particularly a projector that converts an aspect ratio of an image.

  Image signals having various aspect ratios (aspect ratios) are input to the projector in accordance with the format of the image to be displayed (projected image). On the other hand, the size of a light modulation element such as a liquid crystal panel provided in the projector is constant. Therefore, an aspect ratio conversion optical system that converts the aspect ratio of the projected image may be provided when the aspect ratio of the input image is different from the aspect ratio of the light modulation element.

  In recent years, the projection image displayed by a projector has been widened. For example, a cinema scope having an aspect ratio of 2.35: 1 and a two-screen display having an aspect ratio of 8: 3 or 32:10. Image display is also performed. To cope with the widening of the image, simply converting the aspect ratio using the above-described aspect ratio conversion optical system, the number of pixels of the projected image is insufficient compared to the number of pixels of the input image. There is a problem that it is difficult to display an image at a resolution.

  Thus, for example, Patent Document 1 discloses a technique for improving the resolution of the projected image by increasing the pixel density by providing a pixel shifting unit that performs “four-point pixel shifting” for each pixel of the projected image. It is disclosed.

JP 2007-316240 A

  However, although the one disclosed in Patent Document 1 improves the resolution of the projected image by “four-point pixel shift”, the pixel shift is performed with a uniform shift amount regardless of the conversion ratio of the aspect ratio. ing. Therefore, depending on the aspect ratio conversion magnification, the number of pixels required in the input image may differ from the number of pixels in the actual projected image. Due to the difference between the number of pixels of the input image and the number of pixels of the projection image, there is a problem that the resolution required for the input image cannot be obtained in the projection image.

  SUMMARY An advantage of some aspects of the invention is that it provides a projector capable of displaying an image with an appropriate resolution according to a conversion magnification of an aspect ratio.

  In order to solve the above-described problems and achieve the object, the present invention is a projector for displaying a projection image on an irradiated surface using light emitted from a light source unit, and the light emitted from the light source unit is A light modulation element that modulates according to the input image, an aspect ratio conversion unit that receives light modulated by the light modulation element, and optically converts the aspect ratio of the projection image according to the aspect ratio of the input image, and projection A pixel shift unit that shifts the pixels of the image, a calculation unit that calculates a pixel shift amount based on the aspect ratio conversion magnification by the aspect ratio conversion unit, and a pixel shift unit that controls the pixel shift unit to shift the pixel based on the shift amount And a control unit for causing the controller to operate.

  Since the pixel is shifted by the shift amount based on the aspect ratio conversion magnification, the pixel density can be increased according to the aspect ratio conversion magnification. Therefore, an image can be displayed with an appropriate resolution according to the conversion ratio of the aspect ratio.

  Moreover, as a preferable aspect of the present invention, it is preferable that the projection optical system further includes a projection optical system that projects the light modulated by the light modulation element toward the irradiated surface, and the pixel shift unit is included in the projection optical system. By integrating the pixel shifting unit with the projection lens in advance, the pixel shifting unit can be mounted and positioned simply by mounting the projection lens, and the assembly process of the projector can be simplified.

  In addition, as a preferable aspect of the present invention, it is preferable that an aspect ratio determination unit that determines the aspect ratio of the input image is further included, and the calculation unit calculates the conversion magnification based on the aspect ratio of the input image. Since the conversion magnification is calculated based on the aspect ratio of the input image, the image can be displayed with an appropriate resolution corresponding to the aspect ratio of the input image.

  Moreover, as a preferable aspect of the present invention, the image processing apparatus further includes an input unit that inputs an aspect ratio of the input image, and the aspect ratio determination unit can determine the aspect ratio of the input image based on an input result from the input unit. desirable. Since the aspect ratio is determined based on the user's input, it is possible to express an image in accordance with the user's intention.

  In a preferred aspect of the present invention, the aspect ratio conversion unit includes a setting unit that sets the aspect ratio of the projected image, and the aspect ratio determination unit determines the aspect ratio of the input image based on the aspect ratio set by the setting unit. It is desirable to determine the ratio. For example, since the user can intuitively set the aspect ratio while looking at the irradiated surface, the operability can be improved. In addition, an image can be displayed with an appropriate resolution according to an intuitively set aspect ratio.

As a preferred aspect of the present invention, the calculation unit sets the aspect ratio of the input image to xi: yi, sets the modulation-side aspect ratio, which is the aspect ratio of the light modulation element, to xo: yo, and performs the horizontal direction by the aspect ratio conversion unit. When the horizontal conversion magnification of the aspect ratio to ax is set to amx and the vertical conversion magnification of the aspect ratio in the vertical direction by the aspect ratio conversion unit is set to amy, the pixel shift amount nx in the horizontal direction by the pixel shift unit, the vertical direction It is desirable to calculate the pixel shift amount ny with respect to
nx = 1 / amx
ny = 1 / amy
However,
amx = xi / xo
amy = yi / yo

  Since the conversion ratio of the aspect ratio is calculated based on the aspect ratio of the input image and the pixel shift amount is calculated based on the conversion ratio, the image can be displayed with a resolution corresponding to the aspect ratio of the input image. .

As a preferred aspect of the present invention, when the horizontal conversion magnification ratio amx is 2 or more, the control unit shifts the pixel in the horizontal direction by the pixel shift unit regardless of the value of the calculated shift amount nx. was 1/2, if the vertical conversion ratio am y is 2 or more, the shift amount of the pixel in the vertical direction and half by the pixel shifting unit regardless of the value of the shift amount n y calculated It is desirable. When the pixel shift amount is halved, the pixel density can be doubled in the shifted direction. In addition, it is difficult to increase the pixel density twice or more both vertically and horizontally. Therefore, even when the conversion magnification is twice or more, if the pixel shift amount is halved, an image can be displayed with a resolution that is maximized in the possible range.

As a preferred aspect of the present invention, it is desirable that the calculation unit calculates an angle θ for shifting the pixel with respect to the horizontal axis and a pixel shift amount nxy at the angle θ based on the following equations.
θ = atan (ny / nx)

  For example, when pixel shifting is performed collectively with a single mirror as the pixel shifting unit, it is easy to make the mirror operate smoothly by calculating the angle θ and the pixel shift amount nxy in that direction.

1 is a diagram illustrating a schematic configuration of a projector according to a first embodiment of the invention. It is the figure which expanded the wobbling element, Comprising: It is the side view seen along the X-axis. It is the figure which expanded the wobbling element, Comprising: It is the top view seen along the Y-axis. It is the cross-sectional view which cut | disconnected the aspect-ratio conversion part by the surface parallel to a YZ plane. It is the plane sectional view which cut | disconnected the aspect-ratio conversion part by the surface parallel to ZX plane. It is a block diagram for demonstrating the detailed structure of an image process part. It is a figure for demonstrating the high density of the pixel by pixel shifting. It is a figure for demonstrating the high density of the pixel by pixel shifting. It is a figure for demonstrating the high density of the pixel by pixel shifting. It is a figure which shows schematic structure of the projector which concerns on the modification 1 of Example 1 of this invention. It is a figure which shows schematic structure of the projector which concerns on the modification 2 of Example 1 of this invention. It is a figure which shows schematic structure of the projector which concerns on the modification 3 of Example 1 of this invention. It is a figure which shows schematic structure of the projector which concerns on Example 2 of this invention. It is a figure which shows schematic structure of the projector which concerns on Example 3 of this invention. It is a figure which shows schematic structure of the projector which concerns on Example 4 of this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

<About the projector configuration>
FIG. 1 shows a schematic configuration of a projector 1 according to a first embodiment of the invention. The projector 1 is a front projection type projector that projects light onto a screen (not shown) and observes an image by observing light reflected on the screen. The projector 1 has a light source device 2, a drive unit 6, and an image processing unit 8 and is roughly configured. In the description of the embodiment of the present application, the Z axis is an axis parallel to the central axis of the projection lens 48. The Y axis is an axis orthogonal to the Z axis. The X axis is an axis orthogonal to the Y axis and the Z axis. The direction of the arrow on the Z axis represents the direction from the projection lens 48 toward the irradiated surface (not shown). The arrow direction of each axis is a positive direction, and the opposite direction is a negative direction. In the embodiment of the present application, the X axis is also referred to as a horizontal axis, and the direction along the X axis is referred to as a horizontal direction. The Y axis is also referred to as the vertical axis, and the direction along the Y axis is referred to as the vertical direction.

  The light source device 2 includes an arc tube (not shown) such as an ultrahigh pressure mercury lamp, for example, and emits light including red (R) light, green (G) light, and blue (B) light toward the optical engine 4. To do. The light source device 2 may use a semiconductor light source such as an LED. The optical engine 4 includes various lenses and optical elements, and projects the light emitted from the light source device 2 toward the irradiated surface.

  The concave lens 31 collimates the light emitted from the light source device 2. The first integrator lens 32 and the second integrator lens 33 have a plurality of lens elements arranged in an array. The first integrator lens 32 divides the light flux from the concave lens 31 into a plurality of parts. Each lens element of the first integrator lens 32 condenses the light beam from the concave lens 31 in the vicinity of the lens element of the second integrator lens 33. The lens element of the second integrator lens 33 forms an image of the lens element of the first integrator lens 32 on the spatial light modulator.

  The light that has passed through the two integrator lenses 32 and 33 is converted into linearly polarized light in a specific vibration direction by the polarization conversion element 34. The superimposing lens 35 superimposes the image of each lens element of the first integrator lens 32 on the spatial light modulator. The first integrator lens 32, the second integrator lens 33, and the superimposing lens 35 make the light intensity distribution from the light source device 2 uniform on the spatial light modulator. Light from the superimposing lens 35 enters the first dichroic mirror 36. The first dichroic mirror 36 reflects R light and transmits G light and B light. The R light incident on the first dichroic mirror 36 has its optical path bent by the first dichroic mirror 36 and the reflection mirror 37, and is incident on the R light field lens 38R. The R light field lens 38R collimates the R light from the reflection mirror 37 and makes it incident on the R light spatial light modulator 39R.

  The spatial light modulator 39R for R light is a spatial light modulator that can modulate R light according to an input image, and is a transmissive liquid crystal display device configured with a predetermined number of pixels and a predetermined aspect ratio. The aspect ratio of the spatial light modulator is an aspect ratio of an effective area where light can be modulated. In this embodiment, the aspect ratio of each pixel is 1: 1, and the aspect ratio (resolution) of the number of pixels matches the aspect ratio. A liquid crystal panel (not shown) provided in the R light spatial light modulator 39R encloses a liquid crystal layer for modulating light according to an image signal between two transparent substrates. The R light modulated by the R light spatial light modulator 39R is incident on the cross dichroic prism 40 which is a color synthesis optical system.

  The G light and B light transmitted through the first dichroic mirror 36 enter the second dichroic mirror 41. The second dichroic mirror 41 reflects G light and transmits B light. The G light incident on the second dichroic mirror 41 has its optical path bent by the second dichroic mirror 41 and is incident on the G light field lens 38G. The G light field lens 38G collimates the G light from the second dichroic mirror 41 and makes it incident on the G light spatial light modulator 39G. The G light spatial light modulation device 39G is a spatial light modulation device capable of modulating R light in accordance with an input image, and is a transmissive liquid crystal display device having a predetermined number of pixels and a predetermined aspect ratio. The G light modulated by the G light spatial light modulator 39G is incident on a different surface of the cross dichroic prism 40 from the surface on which the R light is incident.

  The B light transmitted through the second dichroic mirror 41 is transmitted through the relay lens 42, and then the optical path is bent by reflection at the reflection mirror 43. The B light from the reflection mirror 43 further passes through the relay lens 44, and then the optical path is bent by reflection by the reflection mirror 45, and enters the B light field lens 38B. Since the optical path of the B light is longer than the optical path of the R light and the optical path of the G light, relay lenses 42 and 44 are provided in the optical path of the B light in order to make the illumination magnification in the spatial light modulator equal to that of other color lights. The relay optical system to be used is adopted.

  The B light field lens 38B collimates the B light from the reflection mirror 45 and makes it incident on the B light spatial light modulator 39B. The B light spatial light modulation device 39B is a spatial light modulation device capable of modulating R light in accordance with an input image, and is a transmissive liquid crystal display device having a predetermined number of pixels and a predetermined aspect ratio. The B light modulated by the B light spatial light modulator 39B is incident on a surface of the cross dichroic prism 40 different from the surface on which the R light is incident and the surface on which the G light is incident.

  The cross dichroic prism 40 has two dichroic films 46 and 47 that are substantially orthogonal to each other. The first dichroic film 46 reflects R light and transmits G light and B light. The second dichroic film 47 reflects B light and transmits R light and G light. The cross dichroic prism 40 combines the R light, G light, and B light incident from different directions, and emits them in the direction of the wobbling element (pixel shift unit) 50.

  FIG. 2A is an enlarged view of the wobbling element 50, and is a side view seen along the X axis. FIG. 2B is an enlarged view of the wobbling element 50, and is a plan view seen along the Y axis. The wobbling element 50 includes a first parallel flat plate 51 and a second parallel flat plate 52. For the first parallel flat plate 51 and the second parallel flat plate 52, a translucent material, for example, glass is used. In the first parallel plate 51 and the second parallel plate 52, the light incident surface and the light exit surface are parallel to each other.

  The first parallel flat plate 51 is rotatable around a rotation shaft 51a. As shown in FIG. 2A, by changing the angle of the first parallel plate 51, the light beam incident on the first parallel plate 51 can be shifted in a direction (longitudinal direction) parallel to the Y axis. The second parallel flat plate 52 is rotatable about a rotation shaft 52a. As illustrated in FIG. 2B, by changing the angle of the second parallel plate 52, the light beam incident on the second parallel plate 52 can be shifted in a direction (lateral direction) parallel to the X axis. The light transmitted through the wobbling element 50 enters the projection lens 48. By shifting the light beam in the horizontal direction and the vertical direction by the wobbling element 50, the pixels in the projected image can be shifted as will be described later. The projection lens 48 includes a plurality of lenses, and magnifies and projects incident light toward the irradiated surface.

  FIG. 3A is a cross-sectional view of the aspect ratio converter 54 cut along a plane parallel to the YZ plane. FIG. 3B is a cross-sectional plan view of the aspect ratio conversion section cut along a plane parallel to the ZX plane. The aspect ratio conversion unit 54 is provided at the subsequent stage of the projection lens, and receives light that is enlarged and projected from the projection lens 48 toward the irradiated surface.

  The aspect ratio conversion unit 54 is provided at a position where light projected from the projection lens 48 enters. The aspect ratio conversion unit 54 includes a first lens group L1 and a second lens group L2. The first lens unit L1 has positive power in a plane cross section (one cross section). The second lens unit L2 has a positive power in a planar cross section (one cross section). The first lens group L1 and the second lens group L2 have no power in the cross section. The lens group L1 and the lens group L2 are configured to include at least one lens. In the present embodiment, the lens group L1 and the lens group L2 will be described as being composed of one lens having different curvatures in a plane cross section and a cross section for the sake of simplicity. In the first lens unit L1, both the light incident surface and the light exit surface are convex in the plane cross section, but the curvature of both surfaces in the cross section is infinite. In the second lens unit L2, both the light incident surface and the light exit surface are concave in the plane cross section, but the curvature of both surfaces in the cross section is infinite.

  Of the two lens groups L1 and L2, the second lens group L2 is movable in parallel along the optical axis. Hereinafter, the side away from the first lens unit L1 in the direction of the projection lens 48 is referred to as the wide-angle side, and the side close to the first lens unit L1 is referred to as the telephoto side. The aspect ratio conversion unit 54 is an afocal optical system, and the second lens group L2 is arranged with the first lens group L1 both when it is arranged on the wide-angle side and when it is arranged on the telephoto side. It has an afocal relationship with the second lens unit L2.

  The aspect ratio converter 54 can change the horizontal width of the projected image by moving the position of the second lens unit L2 to the wide-angle side or the telephoto side. Therefore, the aspect ratio of the projected image is converted depending on the position of the second lens unit L2 of the aspect ratio conversion unit 54. For example, when the second lens unit L2 is arranged on the wide-angle side, an image displayed with an aspect ratio of 4: 3 is moved to the telephoto side so that the aspect ratio is 8 : Can be displayed in a three-screen display. In addition, by changing the position of the second lens unit L2, various aspect ratios can be handled. Both lens groups L1 and L2 may be arranged in such a configuration that the height of the projected image can be changed.

  The driving unit 6 includes a light modulation element driving unit 61, a wobbling element driving unit 62, and a lens group driving unit 63. The light modulation element driving unit 61 drives each of the spatial light modulators 39R, 39G, and 39B for light based on a command from the image processing unit 8 described later, and modulates light according to the image signal. Based on a command from the image processing unit 8, the wobbling element driving unit 62 rotates the first parallel plate 51 and the second parallel plate 52 constituting the wobbling element 50 by a predetermined angle about the rotation shafts 51a and 52a. The lens group driving unit 63 moves the second lens group L2 to the wide angle side or to the telephoto side based on a command from the image processing unit 8.

  FIG. 4 is a block diagram for explaining a detailed configuration of the image processing unit. The image processing unit 8 sends commands to the light modulation element driving unit 61, the wobbling element driving unit 62, and the lens group driving unit 63 in accordance with the input image signal, and the spatial light modulation devices 39R, 39G, and 39B for each light. The wobbling element 50 and the second lens unit L2 are controlled. The image processing unit 8 includes a determination unit 81, an arithmetic control circuit 82, and a scaler 83. Each control by the image processing unit 8 will be described in detail later.

<Calculation of pixel shift amount>
Next, calculation of the pixel shift amount in the projected image by the image processing unit 8 will be described. In the description of calculation of the pixel shift amount, the resolution of the input image (input side resolution) is 640 × 240, and the resolution (modulation side resolution) of each of the spatial light modulators 39R, 39G, and 39B for light is 320 × 240. And That is, the aspect ratio of the input image is 8: 3, and the aspect ratio of each of the light spatial light modulators 39R, 39G, and 39B is 4: 3. The aspect ratio of the input image is the aspect ratio of the input image. In this embodiment, the aspect ratio of each pixel constituting the input image is 1: 1, and the aspect ratio (resolution) of the number of pixels matches the aspect ratio.

  The determination unit 81 functions as a resolution determination unit that determines the input-side resolution from the input image signal. The determination unit 81 functions as an aspect ratio determination unit that determines the aspect ratio of the input image from the input image signal. The determination unit 81 transmits a signal indicating the determined input-side resolution and aspect ratio to the arithmetic control circuit 82. Also, the determination unit 81 transfers the input image signal toward the scaler 83.

When the aspect ratio of the input image is xi: yi and the aspect ratio of the modulator, which is the ratio of the resolutions of the spatial light modulators 39R, 39G, and 39B, is set to xo: yo, the arithmetic control circuit 82 The horizontal conversion magnification ratio amx of the aspect ratio in the horizontal direction by the ratio conversion section 54 and the vertical conversion magnification ratio amy of the aspect ratio in the vertical direction by the aspect ratio conversion section 54 are calculated based on the following formulas (1) and (2). To do.
amx = xi / xo (1)
amy = yi / yo (2)

The arithmetic control circuit 82 calculates the pixel shift amount nx in the horizontal direction by the wobbling element 50, that is, the light beam shift amount by the second parallel plate 52 based on the following mathematical formula (3).
nx = 1 / amx (3)

Further, the arithmetic control circuit 82 calculates the pixel shift amount ny in the vertical direction by the wobbling element 50, that is, the light beam shift amount by the first parallel plate 51 based on the following formula (4).
ny = 1 / amy (4)

  In this description, amx = 8/4 = 2, amy = 3/3 = 1, nx = 1/2, and ny = 1. The unit of nx and ny is a pixel. That is, when nx = 1/2 and ny = 1, it means that the pixels forming the projected image are shifted by 1/2 pixel in the horizontal direction and 1 pixel in the vertical direction on the irradiated surface. When amx = 2 and amy = 1, the number of pixels of each of the spatial light modulators 39R, 39G, and 39B for light is set in the horizontal direction in order to project an image with the fineness required by the input image. It means that it needs to be doubled. Note that the modulation-side resolution and the aspect ratio of each of the spatial light modulators 39R, 39G, and 39B for light are values unique to the projector 1, and these pieces of information are stored in the projector 1 in advance.

  The arithmetic control circuit 82 also sends a command to the wobbling element driving unit 62 based on the calculated nx and ny, and rotates the first parallel plate 51 and the second parallel plate 52 by a predetermined angle from the initial state. The pixel shift is executed. This pixel shift is performed according to a time division cycle in scaling performed by a scaler 83 described later. That is, the parallel plates 51 and 52 are returned to the initial state in the next cycle in which the parallel plates 51 and 52 are rotated, and the parallel plates 51 and 52 are rotated again in the next cycle. Done. In the vertical direction where the conversion magnification is 1, the number of pixels of the input image and the number of pixels of each of the spatial light modulators 39R, 39G, and 39B for light coincide with each other. In addition, shifting pixels by one pixel simply overlaps the pixels. Therefore, it is not necessary to increase the pixel density to be described later in the direction in which the conversion magnification is 1, that is, the direction in which the value of nx or ny is 1. Therefore, the arithmetic control circuit 82 does not shift the pixels in the direction in which the conversion magnification is 1.

  In addition, the arithmetic control circuit 82 sends a command to the lens group driving unit 63 to project a projection image on the irradiated surface with an aspect ratio corresponding to the aspect ratio of the input image, and the second lens group L2. Move to the appropriate position. In addition, the arithmetic control circuit 82 transmits information indicating the calculated conversion magnification to the scaler 83.

  The scaler 83 compresses the input image to the aspect ratio of each of the spatial light modulators 39R, 39G, and 39B for light and performs scaling by dividing the input image into two types of image signals in a time division manner. The time division period is preferably 1/24 seconds or less. The scaler 83 sends a command to the light modulation element driving unit 61 to drive each of the spatial light modulators 39R, 39G, and 39B for light, and to modulate light according to the scaled image signal. Two types of images displayed on the basis of the image signal generated by scaling are displayed at a timing shifted by a time division period. The two types of images are displayed on the irradiated surface at positions shifted from each other by nx and ny pixels due to the pixel shift described above.

<Improvement of resolution (higher pixel density)>
Next, an explanation will be given on the improvement of resolution (higher pixel density) according to the conversion ratio of the aspect ratio. 5 to 7 are diagrams for explaining pixel density increase by pixel shifting. First, with reference to FIG. 5, a description will be given of the increase in density of pixels when each pixel of the projected image is shifted by 1/2 pixel in the horizontal direction. That is, the pixel density increase when the pixel shift amount is nx = 1/2 and ny = 1 and the vertical and horizontal conversion magnifications are amx = 2 and amy = 1 will be described. This conversion magnification is the same as the conversion magnification described in the calculation of the pixel shift amount. In FIG. 5, only some of the pixels constituting the projected image are shown, and the other pixels are omitted. Among the pixels shown in FIG. 5, (a) shows a pixel before pixel shifting, (b) shows a pixel in a state where pixel shifting has been performed, and (c) shows (a) and (b). FIG. 2 schematically shows a state in which pixels shown are synthesized in a pseudo manner.

  The pixel shown in FIG. 5 (a) and the pixel shown in FIG. 5 (b) are displayed at different timings. However, since the period of time division in scaling is very short, both are visually perceived by the viewer. These pixels are superimposed and recognized. By the scaling performed by the scaler 83 described above, pixels are displayed with the component “C + D” in the pixel region 10 shown in FIG. 5A, and pixels are displayed with the component “A + B” in the pixel region 11. 5B, pixels are displayed with a component “D + A”, and pixels are displayed with a component “B + E” in the pixel region 13.

  By artificially synthesizing the pixel shown in FIG. 5A and the pixel shown in FIG. 5B, the viewer recognizes the pixel as shown in FIG. 5C. More specifically, a ½ component of the component displayed in the pixel region 11 and a ½ component of the component displayed in the pixel region 12 are superimposed on the virtual pixel region 14. Therefore, the component displayed in the virtual pixel area 14 is “A / 2 + B / 2 + D / 2 + A / 2 = A + B / 2 + D / 2”. As described above, since the component “A” is recognized most strongly in the virtual pixel region 14, the virtual pixel region 14 can be a pixel in which the component “A” is displayed in a pseudo manner.

  Similarly, the component displayed in the virtual pixel area 15 is “A / 2 + B / 2 + B / 2 + E / 2 = B + A / 2 + E / 2”. Thus, since the component “B” is recognized most strongly in the virtual pixel area 15, the virtual pixel area 15 can be a pixel in which the component “B” is displayed in a pseudo manner.

  As shown in FIG. 5C, the virtual pixel region 14 and the virtual pixel region 15 have the size of the original one pixel. In other words, the virtual pixel region 14 and the virtual pixel region 15 display two pixels in a pseudo manner with respect to the original one pixel region, so that the pixel density can be increased. In this way, by shifting the pixels by 1/2 pixel in the horizontal direction, the pixel density can be doubled in the horizontal direction. That is, the pixel density is doubled according to the lateral conversion magnification amx = 2. In addition, if pixel shift of 1/2 pixel is performed in the vertical direction, the pixel density can be doubled in the vertical direction.

  Next, with reference to FIG. 6, description will be given of pixel density increase when each pixel of the projected image is shifted by 2/3 pixel in the horizontal direction. That is, the pixel density increase when the pixel shift amount is nx = 2/3, ny = 1, and the vertical and horizontal conversion magnifications are amx = 1.5 and amy = 1 will be described. In FIG. 6, only some of the pixels constituting the projected image are shown, and the other pixels are omitted. Among the pixels shown in FIG. 6, (a) shows a pixel before pixel shifting, (b) shows a pixel in a state where pixel shifting has been performed, and (c) shows (a) and (b). FIG. 2 schematically shows a state in which pixels shown are synthesized in a pseudo manner.

  The pixel shown in FIG. 6 (a) and the pixel shown in FIG. 6 (b) are displayed at different timings. However, since the period of time division in scaling is very short, both are visually perceived by the viewer. These pixels are superimposed and recognized. By the scaling performed by the scaler 83 described above, the pixel is displayed with the component “2D + E” in the pixel region 16 illustrated in FIG. 6A, and the pixel is displayed with the component “2A + B” in the pixel region 17. In 18, a pixel is displayed with a component of “B + 2C”. 6B, the pixel is displayed with the component “E + 2A”, the pixel is displayed with the component “2B + C” in the pixel region 20, and the pixel region 21 has “C + 2D”. Pixels are displayed by component.

  By synthesizing the pixels shown in FIG. 6A and the pixels shown in FIG. 6B, the viewer recognizes the pixels as shown in FIG. 6C. More specifically, in the virtual pixel area 22, 2/3 of the components displayed in the pixel area 17 and 2/3 of the components displayed in the pixel area 19 are superimposed. Therefore, the component displayed in the virtual pixel area 22 is “(2A + B) × 2/3 + (E + 2A) × 2/3 = 8A / 3 + 2B / 3 + 2E / 3”. Thus, since the component “A” is recognized most strongly in the virtual pixel region 22, the virtual pixel region 22 can be a pixel in which the component “A” is displayed in a pseudo manner.

  Similarly, the component displayed in the virtual pixel area 23 is “(2A + B) × 1/3 + (B + 2C) × 1/3 + (2B + C) × 2/3 = 2A / 3 + 6B / 3 + 4C / 3”. Thus, since the component “B” is recognized most strongly in the virtual pixel region 23, the virtual pixel region 23 can be a pixel in which the component “B” is displayed in a pseudo manner.

  Similarly, the component displayed in the virtual pixel area 24 is “(B + 2C) × 2/3 + (2B + C) × 1/3 + (C + 2D) × 1/3 = 4B / 3 + 6C / 3 + 2D / 3”. Thus, since the component “C” is recognized most strongly in the virtual pixel region 24, the virtual pixel region 24 can be a pixel in which the component “C” is displayed in a pseudo manner.

  As shown in FIG. 6C, the virtual pixel regions 22, 23, and 24 have the same size as the original two pixels. That is, in the virtual pixel regions 22, 23, and 24, three pixels are displayed in a pseudo manner with respect to the original two pixel regions, so that the density of the pixels can be increased. In this way, by shifting the pixels by 2/3 pixels in the horizontal direction, the pixel density in the horizontal direction can be increased by 1.5 times. That is, the pixel density is increased to 1.5 times in accordance with the lateral conversion magnification amx = 1.5. Note that if the pixel shift of 2/3 pixels is performed in the vertical direction, the pixel density can be increased by 1.5 times in the vertical direction.

  Here, when the horizontal conversion magnification ratio amx becomes amx> 2, the pixel shift amount nx becomes 0 <nx <1/2, but the pixel density in the horizontal direction is not increased more than twice. Therefore, the arithmetic control circuit 82 sets the pixel shift amount nx to nx = 1/2 so that the pixel density is maximized when the lateral conversion magnification amx is amx> 2, and sets the pixel shift amount nx to ½. A command is sent to the drive unit 62. For the same reason for the vertical conversion magnification ratio amy, when amy> 2, the arithmetic control circuit 82 sets the pixel shift amount ny to ny = 1/2 and sends a command to the wobbling element driving unit 62.

  5 and 6, the pixel shift is performed only in the horizontal direction. However, depending on the aspect ratio of the input image and the aspect ratios of the spatial light modulators 39R, 39G, and 39B for each light, that is, the obtained horizontal conversion magnification amx Depending on the vertical conversion magnification ratio amy, the pixel shift amount nx in the horizontal direction, and the pixel shift amount ny in the vertical direction, the pixel shift may be performed in the vertical direction.

  In this way, by shifting the pixels according to the conversion magnification, the pixel density can be increased in a pseudo configuration with a simple configuration without increasing the resolution of the spatial light modulation device. Miniaturization of the projector can be achieved.

  Depending on the difference between the input-side resolution obtained by the discriminating unit 81 (resolution discriminating unit) and the modulation-side resolution previously held in the projector 1, in addition to the above-described pixel shift for aspect ratio conversion, FIG. As shown in FIG. 7, pixel shifting may be performed in both the vertical direction and the horizontal direction. By shifting the pixels in both the vertical and horizontal directions, the pixel density in both the vertical and horizontal directions can be increased as shown in FIG. In this description, a part of the projected image has been described. However, by performing scaling after analyzing the entire projected image, it is possible to obtain a high-definition projected image in which the density of the entire image is increased. it can.

<Restoring the pixel shape>
As shown in FIGS. 5 and 6, the pixel shape may be deformed by performing pixel shifting. In FIGS. 5 and 6, a substantially square square pixel is transformed into a rectangular rectangular pixel by performing pixel shifting. Here, in the present embodiment, the pixel density of the input image and the pixel density of the projected image are made to coincide with each other by performing pixel shift with a shift amount corresponding to the conversion ratio of the aspect ratio. Therefore, if the aspect ratio of the projected image is matched with the aspect ratio of the input image by the aspect ratio conversion unit 54, the deformed pixel shape is restored on the irradiated surface. As described above, in this embodiment, the pixel density is increased according to the conversion ratio of the aspect ratio rather than the uniform pixel density increase, so that the pixel shape of the higher density pixel is restored. Thus, a high-definition image can be displayed on the irradiated surface using pixels having an appropriate shape.

  Thus, since the aspect ratio of the projected image can be converted by the aspect ratio conversion unit 54, it is not necessary to widen the spatial light modulation element in accordance with the widening of the input image. Cost reduction can be achieved by sharing the spatial light modulator.

Note that the pixel shift amount in the pixel shift may be calculated by the arithmetic control circuit 82 based on the following formulas (5) and (6).
nx = 1- (1 / amx) (5)
ny = 1- (1 / amy) (6)

  Here, the pixel shift amounts calculated based on Equations (3) and (4) are 1> nx and ny ≧ 1/2. On the other hand, the pixel shift amount calculated based on the equations (5) and (6) is 1/2 ≧ nx, ny> 0. As described above, the pixel shift amount calculated based on the formulas (5) and (6) is equal to or less than the pixel shift amount calculated based on the formulas (3) and (4), and thus the wobbling element 50 is configured. Thus, the rotation angle of the first parallel plate 51 and the second parallel plate 52 can be reduced. As a result, the load on the wobbling element driving unit 62 can be reduced, and the wobbling element 50 can be driven at a high speed and the configuration can be simplified.

In this embodiment, the pixel shift amount is calculated separately in the horizontal direction and the vertical direction. However, the present invention is not limited to this, and the pixel shift amount and the pixel shift amount may be calculated. Good. For example, the angle θ formed by the pixel shifting direction and the horizontal axis (X axis) may be calculated by the following formula (7), and the shift amount nxy may be calculated by the following formula (8) (also in FIG. 7). reference).
θ = atan (ny / nx) (7)

  As in the wobbling element 50 shown in the present embodiment, a configuration in which an element for shifting pixels in the horizontal direction (second parallel plate 52) and an element for shifting pixels in the vertical direction (first parallel plate 51) are provided separately. Instead, for example, when pixel shifting is performed collectively using a single mirror, it is easy to make the mirror operate smoothly by calculating the angle θ and the amount of shifting the pixel as described above. Become.

  FIG. 8 is a diagram illustrating a schematic configuration of a projector according to the first modification of the first embodiment of the present invention. In the first modification, the wobbling element 50 is incorporated in the projection lens 48. By integrating the wobbling element 50 into the projection lens 48 in this way, the positioning of the wobbling element 50 can be facilitated when the projector 1 is assembled.

  FIG. 9 is a diagram illustrating a schematic configuration of a projector according to the second modification of the first embodiment of the invention. In the second modification, the wobbling element 50 is disposed on the rear stage side of the projection lens 48. With such a configuration, even in a general projector that does not include the wobbling element 50, if the driving of the spatial light modulator is doubled and the wobbling element 50 is arranged on the rear stage side of the projection lens 48, the pixel The density can be increased.

  FIG. 10 is a diagram illustrating a schematic configuration of a projector according to the third modification of the first embodiment of the present invention. In the third modification, the projector 1 includes a relay optical system 90 that forms an intermediate image before the projection lens 48, and the wobbling element 50 is disposed in the intermediate image portion. With this configuration, it is possible to reliably change the optical path of the image light from each of the spatial light modulators 39R, 39G, and 39B for light by the wobbling element 50, and it becomes easy to obtain a high-definition image.

  FIG. 11 is a diagram illustrating a schematic configuration of the projector according to the second embodiment of the invention. The same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The projector 100 according to the second embodiment includes an input unit 92 that allows a user to input an aspect ratio of an input image. The input unit 92 may be configured with a numeric keypad, for example, and the user can input an arbitrary numerical value. The input unit 92 may be composed of a plurality of switches, a predetermined aspect ratio is associated with each switch, and the user can select a resolution by operating the plurality of switches. . In this configuration, the determination unit 81 determines the aspect ratio of the input image based on the input result input from the input unit 92. Further, the arithmetic control circuit 82 calculates the aspect ratio conversion magnifications amx and amy and the pixel shift amounts nx and ny based on the aspect ratio input by the input unit 92. More specifically, in the formulas (1) to (4), the aspect ratio of the input image and the aspect ratios of the spatial light modulators 39R, 39G, and 39B for light may be applied.

  With this configuration, when the user wants to forcibly change the image signal, or when there is an image signal for two screens as an input image, the user selects and displays one of the screens. However, it is possible to express an image according to the user's intention, and the convenience of the projector 100 is improved.

  FIG. 12 is a diagram illustrating a schematic configuration of the projector according to the third embodiment of the invention. The same components as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. The projector 150 according to the third embodiment includes a setting unit 93 that allows the user to set the aspect ratio of the projected image by operating the aspect ratio conversion unit 54. More specifically, the second lens unit L2 can be moved by operating the setting unit 93. In the third embodiment, the determination unit 81 determines the aspect ratio of the projection image based on the position of the second lens unit L2 moved by the operation of the setting unit 93. The aspect ratio of the projected image is the aspect ratio of the projected image. In this embodiment, the aspect ratio of each pixel constituting the projected image is 1: 1, and the aspect ratio (resolution) of the number of pixels matches the aspect ratio. Further, the arithmetic control circuit 82 calculates the aspect ratio conversion magnifications amx and amy and the pixel shift amounts nx and ny based on the aspect ratio input by the input unit 92. More specifically, in the formulas (1) to (4), the aspect ratio of the projected image may be applied to the input side aspect ratio. According to this configuration, even when the user operates the setting unit 93 to arbitrarily change the aspect ratio of the projected image, the pixel density can be increased according to the aspect ratio. In addition, since the user can intuitively set the aspect ratio while looking at the irradiated surface, the operability can be further improved.

  FIG. 13 is a diagram illustrating a schematic configuration of a projector according to the fourth embodiment of the invention. The same components as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. In the projector 200 according to the fourth embodiment, a reflection type modulation device such as a DMD (Digital MicroMirror Device) is used as each of the light spatial light modulation devices 39R, 39G, and 39B. A flat mirror is used for the wobbling element 50. Here, since the swing angle of the light beam is twice the swing angle of the mirror, the use of a plane mirror for the wobbling element 50 can shift the pixel with a small amount of displacement. Therefore, the load on the driving portion of the wobbling element 50 can be reduced, and the pixels can be shifted at high speed with a simple configuration. Note that the reflection type modulation devices used as the spatial light modulation devices 39R, 39G, and 39B for each light may be other reflection type modulation devices such as LCOS (Liquid Crystal on Silicon).

  In addition, a projector is not restricted to the structure provided with a spatial light modulator for every color light. The projector may be configured to modulate two or three or more color lights with one spatial light modulator. The projector is not limited to using a spatial light modulator. The projector may be a so-called rear projector that supplies light to one surface of the screen and observes an image by observing light emitted from the other surface of the screen.

  Further, the wobbling element is not limited to one using a parallel plate or a mirror. For example, the optical element may include a birefringent crystal, and the light beam may be shifted by periodically changing the changing direction of incident light incident on the optical element.

1,100,150,200 projector, 2 light source device, 4 optical engine, 6 drive unit, 8 image processing unit, 10, 11, 12, 13 pixel region, 14, 15 virtual pixel region, 16, 17, 18, 19 , 20, 21 Pixel region, 22, 23, 24 Virtual pixel region, 31 Concave lens, 32 Integrator lens, 33 Integrator lens, 34 Polarization conversion element, 35 Superimposing lens, 36 Dichroic mirror, 37 Reflecting mirror, 38R R light field lens 38G G light field lens, 38B B light field lens, 39R R light spatial light modulator, 39G G light spatial light modulator, 39B B light spatial light modulator, 40 cross dichroic prism, 41 dichroic mirror , 42 Relay lens, 43 Reflection mirror , 44 relay lens, 45 reflecting mirror, 46 dichroic film, 47 dichroic film, 48 projection lens, 50 wobbling element (pixel shifting part), 51 first parallel plate, 51a rotation axis, 52 second parallel plate, 52a rotation axis 54 Aspect ratio conversion unit 61 Light modulation element drive unit 62 Wobbling element drive unit 63 Lens group drive unit 81 Discrimination unit 82 Calculation control circuit 83 Scaler 90 Relay optical system 92 Input unit 93 Setting unit , L1 first lens group, L2 second lens group

Claims (8)

A projector that displays a projected image on an irradiated surface using light emitted from a light source unit,
A light modulation element that modulates light emitted from the light source unit according to an input image;
An aspect ratio conversion unit that receives light modulated by the light modulation element and optically converts the aspect ratio of the projection image according to the aspect ratio of the input image;
A pixel shifting unit for shifting the pixels of the projected image;
A calculation unit that calculates the shift amount of the pixel based on the conversion ratio of the aspect ratio by the aspect ratio conversion unit;
And a control unit that controls the pixel shift unit to shift the pixel based on the shift amount. A projection optical system that projects the light modulated by the light modulation element toward the irradiated surface;
The projector according to claim 1, wherein the pixel shifting unit is included in the projection optical system. An aspect ratio determining unit for determining an aspect ratio of the input image;
The projector according to claim 1, wherein the calculation unit calculates the conversion magnification based on an aspect ratio of the input image. An input unit for inputting an aspect ratio of the input image;
The projector according to claim 3, wherein the aspect ratio determination unit determines an aspect ratio of the input image based on an input result from the input unit. The aspect ratio conversion unit includes a setting unit that sets an aspect ratio of the projected image,
The projector according to claim 3, wherein the aspect ratio determination unit determines an aspect ratio of the input image based on the aspect ratio set by the setting unit. The calculation unit sets the aspect ratio of the input image to xi: yi, sets the modulation-side aspect ratio, which is the resolution ratio of the light modulation element, to xo: yo, and sets the aspect ratio in the horizontal direction by the aspect ratio conversion unit. When the horizontal conversion magnification is amx and the aspect ratio vertical conversion magnification in the vertical direction by the aspect ratio conversion unit is amy,
The pixel shift amount nx in the horizontal direction and the pixel shift amount ny in the vertical direction by the pixel shift unit are calculated based on the following expressions. Projector.
nx = 1 / amx
ny = 1 / amy
However,
amx = xi / xo
amy = yi / yo The controller is
When the horizontal conversion magnification amx is 2 or more, regardless of the calculated shift amount nx, the pixel shift amount in the horizontal direction by the pixel shift unit is halved,
If the is longitudinal conversion magnification am y is 2 or more, and characterized in that the shift amount of pixels in the vertical direction and 1/2 by the pixel shifting unit regardless of the value of the shift amount n y calculated The projector according to claim 6. The projector according to claim 6, wherein the calculation unit calculates an angle θ for shifting the pixel with respect to the horizontal axis and a pixel shift amount nxy at the angle θ based on the following expression.
θ = atan (ny / nx)

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