JP5428885B2 - projector - Google Patents

Description

  The present invention relates to a projector, and more particularly to a projector that displays an image by projecting light according to an image signal.

  Conventionally, various ideas have been made to obtain a high performance effect using a projector. For example, an attempt has been made to project an image on an irradiated surface having a spherical shape or a curved shape using a projector. A method of projecting light from the inside of a spherical surface and viewing an image inside the spherical surface, a method of projecting light from the inside of a spherical transmission screen and viewing an image outside the spherical surface, and a method of viewing an image from the outside of the spherical surface There are various usage modes such as a method of projecting light and viewing an image inside the spherical surface. Usually, a projector is configured so that the best image can be obtained by projecting light onto a flat illuminated surface. Even when an image is projected onto a spherical or curved surface to be irradiated by the projector having such a configuration, only a part of the image is focused, and the other part is out of focus. For example, Patent Document 1 proposes a technique for projecting light from an oblique direction with respect to an irradiated surface to obtain an image that is in focus over a wide range.

Japanese Patent Laid-Open No. 2004-347689

  However, since the technique of Patent Document 1 is also focused when projecting light onto a planar irradiated surface, even when applied to projection onto a spherical or curved surface to be irradiated, It is difficult to focus on a wide range of images. The present invention has been made in view of the above-described problems, and an object thereof is to provide a projector for obtaining an image focused on a wide range by projecting onto a surface to be irradiated having a spherical shape or a curved shape. And

  In order to solve the above-described problems and achieve the object, a projector according to the present invention includes a projection optical system that projects light according to an image signal, and the projection optical system includes at least a first lens group. And a second lens group, wherein the curvature of the field due to field curvature can be adjusted by changing the distance between the first lens group and the second lens group. .

  The projection optical system makes it possible to adjust the degree of field curvature, thereby projecting light onto a spherical or curved surface to be irradiated and reducing focus shift over a wide range. The degree of field curvature can be easily adjusted by moving the first lens group or the second lens group. Thereby, it is possible to obtain an image in which a wide range of focus is obtained not only on a flat irradiated surface but also on a spherical or curved irradiated surface without changing the lens.

  As a preferred aspect of the present invention, it is desirable that the projection optical system has a function of adjusting the focus of the image plane. As a result, an in-focus image can be obtained.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a function of suppressing fluctuations in focal length when adjusting the degree of curvature of the image plane. Thereby, a change in the size of the video can be suppressed.

1 is a diagram showing a schematic configuration of a projector according to an embodiment of the invention. The schematic diagram which shows the optical element in the optical path from each liquid crystal display panel to a projection optical system. The figure explaining the relationship between the best image surface by a field curvature, and the shape of a to-be-irradiated surface. The figure explaining the example which changes the space | interval of a 1st lens group and a 2nd lens group. The graph showing the example of a simulation of the curvature of field in the case of FIG. The figure explaining the example which changes the space | interval of lens groups about three lens groups. The graph showing the example of a simulation of the curvature of field in the case of FIG. The figure explaining the example which changes the space | interval of lens groups about four lens groups. The graph showing the example of a simulation of the curvature of field in the case of FIG.

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

  FIG. 1 is a diagram illustrating a schematic configuration of a projector 1 according to an embodiment of the present invention. The light source 10 is an ultra high pressure mercury lamp, for example, and emits light including R light, G light, and B light. The first integrator lens 11 and the second integrator lens 12 have a plurality of lens elements arranged in an array. The first integrator lens 11 splits the light flux from the light source 10 into a plurality of parts. Each lens element of the first integrator lens 11 condenses the light beam from the light source 10 in the vicinity of the lens element of the second integrator lens 12. The lens element of the second integrator lens 12 forms an image of the lens element of the first integrator lens 11 on the liquid crystal display panels 18R, 18G, and 18B.

  The polarization conversion element 13 converts light from the second integrator lens 12 into predetermined linearly polarized light. The superimposing lens 14 superimposes the image of each lens element of the first integrator lens 11 on the irradiation surface of the liquid crystal display panels 18R, 18G, and 18B. The first dichroic mirror 15 reflects R light incident from the superimposing lens 14 and transmits G light and B light. The R light reflected by the first dichroic mirror 15 passes through the reflection mirror 16 and the field lens 17R and enters the liquid crystal display panel 18R which is a spatial light modulator. The liquid crystal display panel 18R modulates the R light according to the image signal.

  The second dichroic mirror 21 reflects the G light from the first dichroic mirror 15 and transmits the B light. The G light reflected by the second dichroic mirror 21 passes through the field lens 17G and enters the liquid crystal display panel 18G which is a spatial light modulator. The liquid crystal display panel 18G modulates the G light according to the image signal. The B light transmitted through the second dichroic mirror 21 enters the liquid crystal display panel 18B, which is a spatial light modulator, via the relay lenses 22 and 24, the reflection mirrors 23 and 25, and the field lens 17B. The liquid crystal display panel 18B modulates the B light according to the image signal. The cross dichroic prism 19 that is a color combining optical system combines the light modulated by the respective liquid crystal display panels 18R, 18G, and 18B into image light and advances it to the projection optical system 20. The projection optical system 20 projects the light combined by the cross dichroic prism 19 onto the irradiated surface.

  FIG. 2 is a schematic diagram showing optical elements in an optical path from each liquid crystal display panel 18R, 18G, 18B to the projection optical system 20. The projection optical system 20 includes a lens barrel 30, a first lens group 31, and a second lens group 32. The lens barrel 30 supports the first lens group 31 and the second lens group 32. Each of the first lens group 31 and the second lens group 32 includes one or two or more lenses. The first lens group 31 is provided on the emission side of the projection optical system 20 that emits light. The second lens group 32 is provided on the cross dichroic prism 19 side with respect to the second lens group 31.

  The lens barrel 30 is configured to be able to move at least one of the first lens group 31 and the second lens group 32. The distance between the first lens group 31 and the second lens group 32 can be changed by moving at least one of the first lens group 31 and the second lens group 32 in a direction parallel to the optical axis AX. . The projection optical system 20 is configured to be able to adjust the degree of curvature of the image plane due to the curvature of field by changing the distance between the first lens group 31 and the second lens group 32.

  FIG. 3 is a diagram for explaining the relationship between the best image plane due to field curvature and the shape of the irradiated surface suitable for the best image plane. The upper stage in the figure represents a state in which there is almost no field curvature (image plane flat). The best image plane IMG at this time is a plane substantially perpendicular to the optical axis AX of the projection optical system 20. For example, when the best image surface IMG that is a flat surface is projected onto the spherical irradiated surface S1 that is convex on the projection optical system 20 side and focused near the optical axis AX, a large focus shift occurs in the peripheral portion. It will be. Also, when the best image plane IMG that is a flat surface is projected onto the spherical irradiated surface S2 that is concave on the projection optical system 20 side and the focus is focused on the periphery, a large focus shift occurs near the optical axis AX. It will be.

  The middle stage in the drawing represents a state of field curvature (image plane over) in which the focus shifts to the plus side away from the projection optical system 20. The best image plane IMG at this time is a spherical surface convex toward the projection optical system 20 side. On the other hand, it is assumed that the irradiated surface S1 that is convex on the projection optical system 20 side and has the same curvature as the best image plane IMG is arranged so as to be substantially rotationally symmetric about the optical axis AX. By projecting the best image plane IMG onto the irradiated surface S1, it is possible to obtain an image with a small resolution and high resolution over a wide range.

  The lower part of the figure represents a state of field curvature (image plane under) such that the focus shifts to the minus side approaching the projection optical system 20. The best image plane IMG at this time is a spherical surface with the projection optical system 20 side concave. On the other hand, it is assumed that the irradiated surface S2 that is concave on the projection optical system 20 side and has the same curvature as that of the best image plane IMG is arranged so as to be substantially rotationally symmetric about the optical axis AX. By projecting the best image plane IMG onto the irradiated surface S2, it is possible to obtain an image with a small resolution and high resolution over a wide range.

  The projection optical system 20 can adjust the degree of curvature of the image plane and has a function of adjusting the focus position of the image plane by moving the entire lens barrel 30 back and forth. By adjusting the focus position of the image plane to the irradiated surfaces S1 and S2, it is possible to obtain a further focused image. In addition, the projection optical system 20 has a function of suppressing the variation of the focal length by adjusting the position of the lens constituting the projection optical system 20 when adjusting the degree of curvature of the image plane. Thereby, it is possible to suppress a change in the size of the image when the curvature of field is adjusted according to the irradiated surfaces S1 and S2.

  FIG. 4 is a diagram for explaining an example in which the distance between the first lens group 31 and the second lens group 32 is changed. FIG. 5 is a graph showing a simulation example of field curvature in the case of FIG. The vertical axis of each graph shown in FIG. 5 represents the distance from the optical axis AX, and the horizontal axis represents the focus position. The focus position is expressed with reference to the focus position when no curvature of field occurs. In the graph shown in FIG. 5, the curve indicated by the broken line represents the curvature of field of the meridional image plane caused by the meridional ray bundle. In the graph, the curve indicated by the solid line represents the field curvature of the sagittal image plane caused by the sagittal ray bundle.

  For example, when the first lens group 31 and the second lens group 32 are in the state shown in the middle part of FIG. 4, it is assumed that a slight curvature of field occurs as shown in the middle part of FIG. When the first lens group 31 is moved away from the second lens group 32 as shown in the upper part of FIG. 4 from the state shown in the middle part of FIG. To change. When the first lens group 31 is moved closer to the second lens group 32 as shown in the lower part of FIG. 4 from the state shown in the middle part of FIG. 4, the curvature of field becomes the image as shown in the lower part of FIG. It changes to surface under.

  The projection optical system 20 is not limited to the case where the distance between the first lens group 31 and the second lens group 32 is changed by moving the first lens group 31. The projection optical system 20 only needs to change the distance between the first lens group 31 and the second lens group 32 by moving at least one of the first lens group 31 and the second lens group 32. The group 32 may be moved. In addition, the projection optical system 20 adjusts the distance between the first lens group 31 and the second lens group 32 so that the image plane is flat, thereby projecting the image plane onto the irradiated surface that is a flat surface. With respect to the range, it is possible to obtain a video with little focus shift and high resolution.

  Thus, the projector 1 can easily adjust the degree of curvature of the image plane by moving the first lens group 31 or the second lens group 32. As a result, it is possible to obtain a high-resolution image in which a wide range of focus is achieved not only on a flat irradiated surface but also on a spherical or curved irradiated surface without changing the lens. . By using the projector 1 according to the present embodiment, a high effect can be obtained. The projection optical system 20 is not limited to one constituted by two lens groups (the first lens group 31 and the second lens group 32), and may be constituted by three or more lens groups.

  FIG. 6 is a diagram for explaining an example in which the distance between the lens groups is changed when the projection optical system 20 is constituted by three lens groups. FIG. 7 is a graph showing a simulation example of field curvature in the case of FIG. Details of the graph shown in FIG. 7 are the same as those of the graph shown in FIG. The projection optical system 20 includes a first lens group 31, a second lens group 32, and a third lens group 33 provided in order from the exit side.

  For example, when the first lens group 31, the second lens group 32, and the third lens group 33 are in the state shown in the middle part of FIG. 6, it is assumed that a slight curvature of field occurs as shown in the middle part of FIG. When the second lens group 32 is moved in the direction closer to the third lens group 33 (away from the first lens group 31) as shown in the upper stage of FIG. 6 from the state shown in the middle stage of FIG. 7 As shown in the upper stage, the image plane changes to over. When the second lens group 32 is moved from the state shown in the middle part of FIG. 6 toward the first lens group 31 (away from the third lens group 33) as shown in the lower part of FIG. As shown in the lower part of FIG.

  FIG. 8 is a diagram illustrating an example in which the interval between the lens groups is changed when the projection optical system 20 is configured with four lens groups. FIG. 9 is a graph showing a simulation example of field curvature in the case of FIG. Details of the graph shown in FIG. 9 are the same as those of the graph shown in FIG. The projection optical system 20 includes a first lens group 31, a second lens group 32, a third lens group 33, and a fourth lens group 34 provided in order from the exit side.

  For example, when the first lens group 31, the second lens group 32, the third lens group 33, and the fourth lens group 34 are in the state shown in the middle part of FIG. 8, the field curvature is slightly as shown in the middle part of FIG. Suppose it has occurred. Here, from the state shown in the middle stage of FIG. 8, as shown in the upper stage of FIG. 8, the second lens group 32 is moved in the direction approaching the first lens group 31 (away from the third lens group 33), and the third It is assumed that the lens group 33 is moved in a direction approaching the fourth lens group 34 (away from the second lens group 32). In this case, the field curvature changes to the field-over as shown in the upper part of FIG. Further, it is assumed that the second lens group 32 and the third lens group 33 are moved in a direction approaching the first lens group 31 (away from the fourth lens group 34) from the state shown in the middle stage of FIG. In this case, the field curvature changes to the image plane under as shown in the lower part of FIG.

  In this way, even when the projection optical system 20 is configured to include three or more lens groups, the degree of curvature of the image plane can be adjusted by changing the distance between at least two lens groups. In the above embodiment, when there are two, three, or four lens groups, for example, the projection distance on the optical axis is about 3.8 m, and the spherical surface (concave and convex surfaces) has a minimum diameter of about 2 m. It is possible to produce a curvature of field that is in focus. As the projection optical system 20 includes a larger number of lens groups, the meridional image surface and the sagittal image surface can be matched to improve the image quality.

  The projection optical system 20 moves at least one of the lens groups for focus adjustment or the like, for example, in addition to moving at least one of the lens groups for image plane adjustment. As the focus adjustment, for example, the entire projection optical system 20 may be moved, or a lens group other than the lens group to be moved for image plane adjustment may be moved independently.

  The projector 1 is not limited to the case where a transmissive liquid crystal display device is used as the spatial light modulation device. The spatial light modulation device may use a reflective liquid crystal display (Liquid Crystal On Silicon; LCOS), DMD (Digital Micromirror Device), GLV (Grating Light Valve), or the like. Furthermore, the projector 1 is not limited to the one provided with the spatial light modulation device, and may be, for example, a slide projector using a slide having image information.

  As described above, the projector according to the present invention is useful when a high rendering effect is obtained by projecting onto a surface to be irradiated having a spherical shape or a curved shape.

  DESCRIPTION OF SYMBOLS 1 Projector, 10 Light source, 11 1st integrator lens, 12 2nd integrator lens, 13 Polarization conversion element, 14 Superimposition lens, 15 1st dichroic mirror, 16, 23, 25 Reflection mirror, 17R, 17G, 17B Field lens, 18R , 18G, 18B liquid crystal display panel, 19 cross dichroic prism, 20 projection optical system, 21 second dichroic mirror, 22, 24 relay lens, 30 lens barrel, 31 first lens group, 32 second lens group, 33 third lens Group, 34 4th lens group, AX optical axis, S1, S2 Irradiated surface

Claims (2)

A projection optical system that projects light according to an image signal onto a projection surface ;
The projection optical system includes at least a first lens group and a second lens group, and changes the distance between the first lens group and the second lens group, thereby forming a concave surface on the projection surface. or according to a convex shape, Ri curve degree adjustable der of an image plane due to the field curvature, the projector, characterized by further provided with a function of adjusting the focus position of the image plane. The projector according to claim 1, further comprising a function of suppressing a change in focal length when adjusting the degree of curvature of the image plane.

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