JP5767771B2 - projector - Google Patents

Description

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

  Image signals having various aspect ratios (aspect ratios) are input to the projector according to the format of the image to be displayed. Since the size of the light modulation element such as a liquid crystal panel provided in the projector is constant, the display image is provided with a blank portion according to the difference in aspect ratio. For example, when the aspect ratio of the liquid crystal panel is 16: 9 and an image signal with an aspect ratio of 4: 3 is input, blank portions are provided on the left and right portions of the image for display. In addition, when the aspect ratio of the liquid crystal panel is 4: 3 and an image signal having an aspect ratio of 16: 9 is input, blank portions are provided above and below the image and displayed.

  If a blank portion is provided in a part of the image, a part of the display area of the liquid crystal panel cannot be used, which causes degradation of resolution. Further, in the portion corresponding to the blank portion on the liquid crystal panel, the illumination light must be absorbed at all times, so that the life of the liquid crystal panel including the polarizing plate is likely to be reduced.

  Therefore, when the aspect ratio of the liquid crystal panel and the aspect ratio of the image are different, a technique for compressing an image in a predetermined direction and making it incident on the liquid crystal panel and restoring it with an anamorphic lens after passing through the liquid crystal panel is disclosed in, for example, Patent Document 1 Proposed. When an image signal having the same aspect ratio as that of the liquid crystal panel is input, a mirror is inserted on the optical path to bypass the route not via the anamorphic lens. Further, for example, Patent Document 2 proposes a technique that enables switching between two types of aspect ratios by rotation of an anamorphic lens.

Japanese Patent Laid-Open No. 4-170178 JP-A-6-253242

  However, the one disclosed in Patent Document 1 requires a mirror for detouring the optical path and a mechanism for moving the mirror, resulting in a problem that the structure becomes complicated. Further, the image disclosed in Patent Document 2 has a problem that the aspect ratio of the image that can be handled is limited to two types, and the degree of freedom in design is reduced.

  In addition, there is a so-called proximity projection type projector that can project light with a wide angle and project light from a position close to the screen. When the above-described configuration is used for a proximity projection type projector, in order to make the light having a wide angle incident, the size of the anamorphic lens and the size of the mirror are increased, and the size of the projector itself is increased. Problem arises. Also, it is difficult to store a mechanism for moving the mirror.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a projector that can cope with various aspect ratios while suppressing deterioration in image quality while suppressing an increase in size of the apparatus.

  In order to solve the above-described problems and achieve the object, the present invention is a projector that displays an image on a surface to be irradiated using light emitted from a light source unit, and images the light emitted from the light source unit. A light modulation element that modulates in accordance with a signal; a first optical system that refracts light modulated by the light modulation element; and at least one concave mirror that reflects and widens the light refracted by the first optical system. A second optical system, and an aspect ratio conversion unit that is arranged in an optical path between the light modulation element and the second optical system and converts an aspect ratio of an image displayed on the irradiated surface. And

  Since the aspect ratio conversion unit is disposed between the light modulation element and the second optical system, that is, before the second optical system, the aspect ratio is converted before the light is widened by the second optical system. be able to. Thereby, the enlargement of the aspect ratio conversion unit can be suppressed, and consequently the enlargement of the projector itself can be suppressed.

  Moreover, as a preferable aspect of the present invention, it is desirable that the aspect ratio conversion unit is disposed in the optical path between the first optical system and the second optical system. With this configuration, the aspect ratio can be converted before the light is widened by the second optical system. Thereby, the enlargement of the aspect ratio conversion unit can be suppressed, and consequently the enlargement of the projector itself can be suppressed.

  As a preferred aspect of the present invention, the aspect ratio conversion unit includes a first lens group having a positive power in one section and a second lens group having a negative power in the same section as the first lens group. It is desirable that the afocal optical system includes With this configuration, the aspect ratio of the image can be converted with a simple configuration including two lens groups. Further, by changing the distance between the two lens groups, the image can be converted into various aspect ratios.

  As a preferred aspect of the present invention, it is desirable that the first lens group and the second lens group have no power in a cross section perpendicular to one cross section. Since only one of the cross-sections perpendicular to each other has power, the aspect ratio is changed by changing only the cross-sectional direction of the image in the vertical and horizontal directions, changing both the vertical and horizontal directions of the image. Control of aspect ratio conversion can be simplified as compared with the case of making it.

  Further, as a preferable aspect of the present invention, based on a determination result by the determination unit, a moving unit that moves at least one of the first lens group and the second lens group, a determination unit that determines the aspect ratio of the image, and the like. It is desirable to further include distance control means for controlling the moving means to change the distance between the first lens group and the second lens group. Since the position of the lens group is changed based on the discrimination result of the aspect ratio by the discrimination means, it is possible to display an image with an appropriate aspect ratio while suppressing image degradation without bothering the user.

  Further, as a preferred aspect of the present invention, a distance measuring unit that measures a distance between a moving unit that moves at least one of the first lens group and the second lens group and a distance between the first lens group and the second lens group. It is desirable to change the aspect ratio of the image based on the measurement results of the means and the distance measuring means.

  Even if the distance between the first lens group and the second lens group is changed manually, an image with an optimum aspect ratio can be displayed, so that the image is deteriorated without bothering the user. It is possible to display an image with an appropriate aspect ratio while suppressing this.

FIG. 3 is a perspective view showing a usage state of the projector according to the embodiment of the invention. FIG. 2 is a cross-sectional view showing a schematic configuration inside the projector. The figure which shows schematic structure of a projection optical part. The (a) transverse cross section of an aspect-ratio conversion part, (b) plane sectional drawing. FIG. 6 is a plan sectional view of an aspect ratio conversion unit in which a second lens group is disposed on the wide angle side. FIG. 5 is a plan sectional view of an aspect ratio conversion unit in which a second lens group is disposed on the telephoto side. FIG. 3 is a diagram illustrating a schematic configuration of an image forming optical unit. The block diagram which shows schematic structure of a control system. The block diagram which shows schematic structure of the modification of a control system.

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

  FIG. 1 is a perspective view showing a usage state of a projector according to an embodiment of the invention. FIG. 2 is a cross-sectional view showing a schematic configuration inside the projector. The projector 1 is a front projection type projector that projects an image on a screen to display an image. The observer observes the image displayed on the screen. The projector 1 is a proximity projection type projector that projects an image having a wide angle from a position close to the screen 10 to display an image.

  The screen 10 is a reflection type projection plate, and displays an image by diffusely reflecting incident light incident on a front screen projection surface (irradiated surface) 10a. The axis along the normal line of the screen projection surface 10a is taken as the Z axis. The axes orthogonal to the Z axis and perpendicular to each other are defined as an X axis and a Y axis.

  The projector 1 generally includes a housing 2, a projection optical unit 50, and an image forming optical unit 60. The projection optical unit 50 and the image forming optical unit 60 are provided inside the housing 2. The housing 2 is formed with an opening 2a for emitting the projection light projected from the projection optical unit 50 to the outside.

  The projection optical unit 50 is for enlarging and projecting an image on the object surface OS onto the screen projection surface 10 a of the screen 10. The projection optical unit 50 includes a refractive optical system (first optical system) 4, a reflection optical system (second optical system) 6, and an aspect ratio conversion unit 8. The refractive optical system 4 includes a plurality of lenses, and the reflective optical system 6 includes at least one concave mirror.

  FIG. 3 is a diagram showing a schematic configuration of the projection optical unit 50. The refractive optical system 4 is composed of a plurality of refractive lenses arranged along the optical axis OA extending perpendicularly to the screen projection surface 10a below the screen 10 in FIG. Each lens is arranged from the object surface OS side toward the reflective optical system 6. Each lens is rotationally symmetric with respect to the optical axis OA. Note that all or part of each lens may be non-rotationally symmetric. The arrangement of each lens is adjusted so that an optimal projection can be performed on the screen 10 in relation to the shape and arrangement of the reflective optical system 6 and the like. The optical axis OA is not limited to the case where it extends perpendicularly to the screen projection surface 10a. Further, some or all of the optical axes of the lenses may not be the same.

  From each object point on the object surface OS, a light beam having a certain spread around the principal ray perpendicular to the object surface OS and parallel to the optical axis OA is emitted. The light beam emitted from the object surface OS is refracted when passing through the refractive optical system 4 and travels downward from the optical axis OA. The light that has passed through the refractive optical system 4 is reflected by the reflection optical system 6 provided below the optical axis OA and projected onto the screen 10 as radial projection light.

  The reflective optical system 6 includes a single concave mirror 31. The concave mirror 31 is composed of a rotationally symmetric surface with the optical axis OA as an axis, and the reflecting surface has a concave shape. The concave mirror 31 reflects light on the lower side of the optical axis OA, that is, on the opposite side of the screen 10 across the optical axis OA. The concave mirror 31 reflects the light beam that has passed through the refractive optical system 4 toward the screen projection surface 10 a of the screen 10. The reflective optical system 6 may be configured with a plurality of concave mirrors.

  The light beam that has passed through the refractive optical system 4 is reflected by the concave mirror 31 that is a concave reflecting mirror so as to converge once and then diffuse. That is, the concave mirror 31 exhibits the function of widening the projection light. As described above, in the projector that widens the projection light by the concave mirror 31, the intermediate image 55 is formed before the light that has passed through the refractive optical system 4 enters the reflective optical system 6.

  FIG. 4 is a partially enlarged view for explaining the detailed configuration of the aspect ratio conversion unit 8. FIG. 4A shows the aspect ratio conversion unit 8 from the horizontal direction side (the negative direction side along the X axis). The cross-sectional view seen, (b) is a plan cross-sectional view of the aspect ratio converter 8 viewed from the upper side (positive direction side along the Y axis). The aspect ratio conversion unit 8 is disposed in the optical path between the refractive optical system 4 and the reflective optical system 6. The position at which the aspect ratio conversion unit 8 is disposed is not limited to this, and may be disposed in an optical path between each spatial light modulator for light described later and the reflection optical system 6.

  The aspect ratio conversion unit 8 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 OA. Hereinafter, the side away from the first lens unit L1 in the direction of the reflective optical system 6 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.

  5 and 6 are diagrams for explaining the principle of aspect ratio conversion by the aspect ratio conversion unit 8. In FIG. 5, the second lens unit L2 is arranged on the wide-angle side, and in FIG. The lens unit L2 is disposed on the telephoto side. The aspect ratio conversion unit 8 is an afocal optical system, and the second lens group L2 is arranged with the first lens group L1 both in the case of being arranged on the wide angle side and in the case of being arranged on the telephoto side. It has an afocal relationship with the second lens unit L2. 5 and 6 show only a planar cross section.

  As shown in FIG. 5, the light beam emitted from the refractive optical system 4 passes through the first lens group L1 and the second lens group L2, so that the width in the X-axis direction is narrowed. As shown in FIG. 6, even when the second lens unit L2 is disposed on the telephoto side, the light beam emitted from the refractive optical system 4 is narrowed in the X-axis direction.

  Here, the width of the light beam emitted from the refractive optical unit 4 is x1, the width of the light beam that has passed through the second lens unit L2 disposed on the wide-angle side is x2, and the second lens disposed on the telephoto side. If the width of the light beam that has passed through the group L2 is x3, the relationship is x1> x3> x2.

  Since both lens groups L1 and L2 are anamorphic lenses, the width of the light beam in the Y-axis direction is the same regardless of whether the second lens group L2 is disposed on the wide-angle side or the telephoto side. Almost no change.

  In this embodiment, the first lens group L1 and the second lens group L2 are described as being composed of one lens, but various aberrations such as chromatic aberration, In order to maintain an afocal relationship when the zoom lens is changed from the telephoto side to the telephoto side, it may be constituted by a plurality of lenses. Moreover, you may have a mechanism in which lenses other than between the 1st lens group L1 and the 2nd lens group L2 move.

  In this way, the width of the light beam emitted from the refractive optical system 4 in only one direction can be narrowed only by changing the position of the second lens unit L2 from the telephoto side to the wide angle side. In this embodiment, it is possible to change the aspect ratio of the image displayed on the screen 10 by changing the horizontal width of the intermediate image 55. For example, a 14: 9 image can be compressed horizontally to form a 4: 3 image. In addition, by changing the position of the second lens unit L2, various aspect ratios can be handled. Note that both lens groups L1 and L2 may be arranged so as to compress the image in the vertical direction.

  Next, the image forming optical unit 60 will be described. FIG. 7 is a diagram illustrating a schematic configuration of the image forming optical unit 60. The arc tube 70 is a light source unit that emits light including red (R) light, green (G) light, and blue (B) light, and is, for example, an ultra-high pressure mercury lamp.

  The first integrator lens 71 and the second integrator lens 72 have a plurality of lens elements arranged in an array. The first integrator lens 71 divides the light flux from the arc tube 70 into a plurality of parts. Each lens element of the first integrator lens 71 condenses the light beam from the arc tube 70 in the vicinity of the lens element of the second integrator lens 72. The lens element of the second integrator lens 72 forms an image of the lens element of the first integrator lens 71 on the spatial light modulator.

  The light that has passed through the two integrator lenses 71 and 72 is converted into linearly polarized light in a specific vibration direction by the polarization conversion element 73. The superimposing lens 74 superimposes the image of each lens element of the first integrator lens 71 on the spatial light modulator. The first integrator lens 71, the second integrator lens 72, and the superimposing lens 74 make the light intensity distribution from the arc tube 70 uniform on the spatial light modulator. The light from the superimposing lens 74 enters the first dichroic mirror 75. The first dichroic mirror 75 reflects R light and transmits G light and B light. The R light reflected by the first dichroic mirror 75 has its optical path bent by the first dichroic mirror 75 and the reflection mirror 76, and enters the R light field lens 77R. The R light field lens 77R collimates the R light from the reflection mirror 76 and makes it incident on the R light spatial light modulator 14R.

  The spatial light modulator 14R for R light is a spatial light modulator that modulates R light according to an image signal. The R light modulated by the R light spatial light modulator 14R is incident on a cross dichroic prism 80 which is a color synthesis optical system.

  The G light and B light that have passed through the first dichroic mirror 75 enter the second dichroic mirror 81. The second dichroic mirror 81 reflects G light and transmits B light. The G light reflected by the second dichroic mirror 81 has its optical path bent by the second dichroic mirror 81 and enters the G light field lens 77G. The G light field lens 77G collimates the G light from the second dichroic mirror 81 and makes it incident on the G light spatial light modulator 14G. The spatial light modulation device 14G for G light is a spatial light modulation device that modulates G light according to an image signal. The G light modulated by the G light spatial light modulator 14G is incident on a different surface of the cross dichroic prism 80 from the surface on which the R light is incident. Each of the light spatial light modulators 14R, 14G, and 14B is a transmissive modulation element, such as a liquid crystal panel.

  The B light transmitted through the second dichroic mirror 81 is transmitted through the relay lens 82, and then the optical path is bent by reflection at the reflection mirror 83. The B light from the reflection mirror 83 further passes through the relay lens 84, and then the optical path is bent by reflection by the reflection mirror 85, and enters the B light field lens 77B. 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 82 and 84 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 77B collimates the B light from the reflection mirror 85 and makes it incident on the B light spatial light modulator 14B. The B light spatial light modulation device 14B is a spatial light modulation device that modulates B light according to an image signal. The B light modulated by the B light spatial light modulator 14B is incident on a surface of the cross dichroic prism 80 that is 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 80 has two dichroic films 86 and 87 arranged so as to be substantially orthogonal to each other. The first dichroic film 86 reflects R light and transmits G light and B light. The second dichroic film 87 reflects B light and transmits R light and G light. The cross dichroic prism 80 combines R light, G light, and B light incident from different directions, and emits the light toward the projection optical unit 50. The image light emitted from the cross dichroic prism 80 is projected through the refractive optical system 4 of the projection optical unit 50 and the like.

  FIG. 8 is a block diagram illustrating a schematic configuration of the control system S of the projector 1. The control system S of the projector 1 includes a moving unit 18, an image control unit 20, and a distance control unit (distance control unit) 22. The moving means 18 has a function of moving the second lens group L2. For example, a motor is used as the moving means 18. The image control unit 20 controls each of the spatial light modulators 14R, 14G, 14B and the like included in the image forming optical unit 60 according to the image signal. The image control unit 20 functions as a determination unit that determines the image aspect ratio from the image signal. The image control unit 20 transmits the determination result of the aspect ratio to the distance control unit 22. The distance control unit 22 controls the moving unit 18 based on the determination result of the aspect ratio to move the second lens unit L2, and the distance between the first lens unit L1 and the second lens unit L2 is determined. Try to be appropriate.

  As described above, since the moving unit 18, the image control unit 20, and the distance control unit 22 cooperate to control the position of the second lens unit L2 in accordance with the image signal, the user's hand is not bothered. The image can be displayed with an appropriate aspect ratio while suppressing the deterioration of the image.

  FIG. 9 is a block diagram illustrating a schematic configuration of a modified example of the control system S of the projector 1. The control system S of the projector 1 includes a distance measuring unit 18a and an image control unit 20. The distance measuring unit 18a measures the distance between the first lens group L1 and the second lens group L2. For example, an encoder is used as the distance measuring means 18a. The image control unit 20 calculates the aspect ratio of the projection optical system from the measurement result of the distance measuring unit 18a, and each spatial light modulator for light included in the image forming optical unit 60 includes the image signal corrected to the aspect ratio. 14R, 14G, 14B, etc.

  Thus, even if the distance between the first lens group and the second lens group is manually changed, an image with an optimal aspect ratio can be displayed, so that the user's hands are not bothered. The image can be displayed with an appropriate aspect ratio while suppressing the deterioration of the image.

  Note that, as in the configuration shown in FIG. 8, the function of controlling the positions of the lens groups L1 and L2 according to the image signal, and the image according to the positions of the lens groups L1 and L2 as in the configuration shown in the present modification. The function of controlling the signal may be selected and switched by the user.

  In this embodiment, the projector is described as a front projection type projector. However, a rear projection type projector may be used as a matter of course. In the present embodiment, the second lens group L2 is movable. However, the first lens group L1 may be movable, or both the lens groups L1 and L2 may be movable. That is, any configuration is possible as long as the distance between the first lens unit L1 and the second lens unit L2 is variable.

L1 first lens group, L2 second lens group, S control system, 1 projector, 2 housing, 2a opening, 4 refractive optical system (first optical system), 6 reflective optical system (second optical system) , 8 Aspect ratio conversion unit, 10 screen, 10a Screen projection surface (irradiated surface), 14R R light spatial light modulation element (first light modulation element), 14G G light spatial light modulation element (first light modulation element) ), 14B spatial light modulation element for B light (first light modulation element), 18 movement means, 18a distance measurement means, 20 image control section (discrimination means), 22 distance control section (distance control means), 31 concave mirror, 50 Projection optics, 55 Intermediate image, 60 Image formation optics, 70 Arc tube, 71 First integrator lens, 72 Second integrator lens, 73 Polarization conversion element, 74 Superposition lens, 75 1 dichroic mirror, 76 reflection mirror, 77R R light field lens, 77G G light field lens, 77B B light field lens, 80 cross dichroic prism, 81 second dichroic mirror, 82 relay lens, 83 reflection mirror, 84 relay Lens, 85 reflection mirror, 86 first dichroic film, 87 second dichroic film

Claims (5)

A projector that displays an 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 image signal;
A first optical system that refracts the light modulated by the light modulation element;
A second optical system comprising at least one concave mirror that reflects and widens the light refracted by the first optical system;
Have a, and aspect ratio conversion unit for converting the aspect ratio of the image is arranged in the optical path, is displayed on the illuminated surface between the second optical system and the optical modulator,
The aspect ratio converter is disposed in an optical path between the first optical system and the second optical system,
A projector that forms an intermediate image in front of the second optical system . The aspect ratio converter includes a first lens group having a positive power in one section and a second lens group having a negative power in the same section as the first lens group. The projector according to claim 1, wherein the projector is a system. The projector according to claim 2 , wherein the first lens group and the second lens group do not have power in a cross section perpendicular to the one cross section. Moving means for moving at least one of the first lens group and the second lens group;
Determining means for determining an aspect ratio of the image;
And a distance control unit configured to control the moving unit based on a determination result by the determination unit to change a distance between the first lens group and the second lens group. Item 4. The projector according to Item 2 or 3 . Moving means for moving at least one of the first lens group and the second lens group;
Distance measuring means for measuring a distance between the first lens group and the second lens group;
The projector according to claim 2 or 3 on the basis of the measurement result of said distance measuring means, and changes the aspect ratio of the image.

Images