JP2008191496A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of properly adjusting the luminance, contrast, and luminance distribution of the output light. <P>SOLUTION: The projector includes a light source 11; a color wheel 12 for color-separating the light emitted from the light source 11 by the time division; a rod 13 for increasing the homogeneity of the color-separated light; a relay lens part 14 as a light-gathering means; an optical diaphragm 15 for adjusting the opening degree of the diaphragm in the relay lens part 14; an image display element 16 for converting the light of each color into image display light based on the image signal; a projection optical system 17 for projecting the converted image display light outward; and a control part 24 for controlling the sliding of the rod 13. The rod 13 is made up of two light guide tubes of which the inner slope and the outer slope of the cross section are both rectangular, with the inner surfaces serving as reflecting surfaces and which are configured to be slidable with respect to each other. The control part 24 controls the opening degree of the optical diaphragm, according to the setting of the projection mode and performs control of the sliding of the rod. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projector capable of adjusting the brightness and contrast of a projected image.

  In the field of presentation or video projection, a projector that projects video on a projection surface such as an external screen or wall by projecting light to the outside is used. Such a projector is configured to convert incident light into video display light based on a video signal when the incident light is reflected or transmitted by a video display means such as a liquid crystal panel or a DMD (Digital Micromirror Device), and project the image as projection video to the outside. It has become.

  It is desirable that the luminance distribution of the projected image of the projector be as uniform as possible. For this reason, a rod integrator optical system is usually used for the purpose of improving the uniformity of the illuminance distribution of the image display means (see, for example, Patent Documents 1 to 4). The light emitted from the light source and incident from the incident surface of the rod is repeatedly reflected inside the rod, so that the angle component with respect to the optical axis when emitted from the rod is made uniform. The rod length is set to a length corresponding to the light emission characteristics from the rod. By using the rod, it is possible to improve the luminance distribution while suppressing a decrease in luminance of the projected image to some extent.

  On the other hand, high-brightness projection images are suitable for viewing in a bright room, even at the expense of some contrast, but for viewing in a dark room, a higher contrast is more suitable for viewing than high-brightness. . For this reason, a system that employs a variable aperture mechanism has been put to practical use as means for increasing the contrast while lowering the brightness of the projected image (see Patent Document 5).

FIG. 8 is a schematic diagram schematically showing a relationship between an optical path and a diaphragm of a conventional projector. Light emitted from the light source 11 passes through the color wheel 12 and enters the rod 13. The light that has repeatedly reflected inside the rod 13 and is emitted from the rod 13 is condensed on the image display element 16 through the relay lens unit 14 and the optical aperture 15. The image display light converted from the incident light in the image display element 16 is projected to the outside by the projection optical system 17 as a projection image. In FIG. 8A, the optical path when the optical aperture 15 is opened is shown by a solid line, and in FIG. 8B, the optical path when the optical aperture 15 is stopped is shown by a solid line. When the optical aperture 15 is stopped, the brightness of the projected image can be lowered moderately, and the contrast can be improved by blocking unnecessary light such as scattered light in the optical system.
JP 2003-57602 A JP 2003-140090 A JP 2004-302253 A JP 2005-148707 A JP 2003-107396 A

  However, among the light beams that are incident on the rod 13 from the light source 11 and are repeatedly reflected inside the rod 13 when the optical aperture 15 is stopped, a component having a large number of reflections inside the rod 13 is the optical aperture. 15, the component reaching the image display element 16 is mostly composed of components with a small number of reflections inside the rod 13. In this case, since the image display element 16 is not uniformly irradiated in the conventional projector, the luminance distribution of the converted image display light and the projected image is deteriorated. There is a problem that uneven brightness distribution of the projected image on the surface is conspicuous.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the luminance and luminance distribution of the image display light by sliding the rod in accordance with the content of instructions related to sliding of the rod. It is an object of the present invention to provide a projector that can be adjusted appropriately.

  Another object of the present invention is to appropriately adjust the luminance and luminance distribution of video display light by selectively positioning one of a plurality of rods at a predetermined position in accordance with the content of instructions related to rod selection. It is an object of the present invention to provide a projector that can do this.

  Another object of the present invention is to control the degree of opening of the optical aperture means in accordance with the contents of instructions related to the sliding or selection of the rod, and to control one of the plurality of rods or to control the sliding of the rod. It is an object of the present invention to provide a projector that can appropriately adjust the luminance distribution when the luminance and contrast of a projected image are changed by performing control to selectively position the projector on the position.

  Another object of the present invention is to provide a projector that suppresses light loss by making the shape of the exit surface of the rod and the shape of the image display means substantially similar.

  A projector according to the present invention includes a light source, a tubular rod having an inner surface as a reflection surface and an end surface facing the light source, and image display means for converting light emitted from the rod into image display light and emitting the image display light. In the projector, the rod is slidably inserted into a first light guide tube provided on the light source side and a second light guide tube fixed on the video display means side, and the light source and the first light guide are provided. A base supporting the tube, base driving means for driving the base in a direction in which the first light guide tube slides with respect to the second light guide tube, and an instruction relating to sliding of the rod. It comprises: a receiving unit that receives the control unit, and a control unit that controls the base driving unit so that the position of the base changes according to the instruction content received by the receiving unit.

  In the present invention, when the instruction content received by the receiving means is to increase the luminance, the direction is to shorten the rod length, and when the instruction content is to make the luminance distribution uniform, the direction is to extend the rod length. The base is driven to slide the rod. By driving the base and shortening or extending the rod length, if the content of the instruction is to increase the luminance, the number of reflections inside the rod is reduced, the reflection loss is suppressed, and the luminance is increased. Further, when the instruction content is to make the luminance distribution uniform, the number of reflections inside the rod increases, and the light becomes more uniform. The light generated by the light source is incident on the rod from the first light guide tube, and the angle component with respect to the optical axis when the light is emitted from the second light guide tube is repeatedly reflected on the inner surface of the rod according to the rod length. It is made uniform according to the length. The light emitted from the rod enters the image display means and is converted into image display light.

  A projector according to the present invention includes a light source, a light guide rod having a predetermined length with an end face opposed to the light source, and a video display unit that converts light from the light source into video display light and emits the light. The rod is one of a light guide tube having an inner surface as a reflection surface and a different inner diameter, and a rod-shaped light guide having a different refractive index or a different light guide path diameter, and has two or more different types of rods. Selection means for selectively positioning any one of the rods at a predetermined position in an optical path from the light source to the image display means; reception means for receiving an instruction relating to selection of the rod; and the reception Control means for controlling the selection means so as to position any one of the rods at the predetermined position in accordance with the instruction content received by the means.

  In the present invention, when the instruction content received by the receiving means is to increase the brightness, a rod-shaped light guide having a higher refractive index and a larger light guide path diameter, or a light guide tube A rod having a larger inner diameter is selected, and when the diameter of the light guide path of the rod-shaped light guide is the same as the inner diameter of the light guide tube, the rod-shaped light guide is selected. If the instruction content is to make the luminance distribution uniform, select a rod-shaped light guide with a lower refractive index and a smaller light guide path diameter, or a light guide tube with a smaller inner diameter. When the light guide path diameter of the rod-shaped light guide and the inner diameter of the light guide tube are the same, the light guide tube is selected. By selecting as described above, when the instruction content is to increase the luminance, the number of reflections inside the rod is reduced, and the reflection loss is suppressed to increase the luminance. When the content of the instruction is to make the luminance distribution uniform, the number of reflections inside the rod increases and the light becomes more uniform. The selected rod is positioned at a predetermined position in the optical path from the light source to the image display means. The light generated by the light source is incident on the rod located at a predetermined position, and by repeating the number of reflections according to the rod selected on the inner surface of the rod, the angle component with respect to the optical axis when emitted from the rod is applied to the selected rod. It is made uniform accordingly. The light emitted from the rod enters the image display means and is converted into image display light.

  The projector according to the present invention includes a condensing unit that condenses the light emitted from the rod on the image display unit, an optical diaphragm unit that adjusts an aperture of the diaphragm by the condensing unit, and the image display light. Projection means for projecting to the outside, and the control means controls the opening of the optical diaphragm means in accordance with the contents of the instruction.

  In the present invention, the light generated by the light source is incident on the rod, and the light emitted from the rod is incident on the image display means through the light collecting means and the optical aperture means. The video display means converts incident light into video display light, and the projection means projects the video display light to the outside. The control means controls the opening degree of the optical diaphragm means in accordance with the contents of instructions related to the sliding or selection of the rod, and controls the sliding of the rod by driving the base or any one of a plurality of rods. Control to selectively position at the position. By controlling the opening of the optical aperture means, the contrast of the image display light and the projected image is also adjusted.

  The projector according to the present invention is characterized in that the shape of the exit surface of the rod and the shape of the video display means are substantially similar.

  In the present invention, the shape of the exit surface of the rod is rectangular and is substantially similar to the shape of the image display means, whereby the aspect ratio of the cross-sectional shape of the light beam emitted from the rod and the aspect ratio of the image display means Are substantially the same.

  According to the present invention, the luminance and luminance distribution of the light emitted from the rod is adjusted according to the rod length by the control of sliding the rod by driving the base, and the environment for viewing the luminance and luminance distribution of the video display light is appreciated. It is possible to adjust to suit the light and dark.

  According to the present invention, by controlling to selectively position one of the plurality of rods at a predetermined position, the luminance and luminance distribution of the emitted light from the rod are adjusted according to the selected rod, and the image display light It is possible to adjust the brightness and the brightness distribution so as to be suitable for the brightness and darkness of the environment where the user appreciates.

  According to the present invention, the optical aperture can be controlled by controlling the opening of the optical aperture means and controlling the slide of the rod by driving the base or selectively positioning any one of the plurality of rods at a predetermined position. The brightness, contrast, and brightness distribution of the image display light are adjusted in conjunction with the opening of the means, and the brightness distribution when the brightness and contrast of the projected image is changed to be suitable for the brightness of the viewing environment. Is possible

  According to the present invention, since the aspect ratio of the cross-sectional shape of the light beam emitted from the rod and the aspect ratio of the image display means are substantially the same, the light emitted outside the range of the image display means is reduced, and the projector Light loss can be suppressed.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a projector according to Embodiment 1 of the present invention, and white arrows in the figure indicate light. FIG. 2 is a perspective view schematically showing a mechanism for slidingly expanding and contracting the rod, and a black arrow in the drawing indicates a direction in which the base 18 is moved. FIG. 2A shows a case where the rod 13 is shortened, and FIG. 2B shows a case where the rod 13 is extended.

  1 and 2, 11 is a light source, and the light source 11 is composed of a light emitter such as a discharge lamp that emits white light and a reflecting mirror having a concave surface of a semi-elliptical spherical shell whose inner surface is mirror-finished, The light emitted from the light emitter is condensed in the direction of the concave opening. The light source 11 is sandwiched between light source holding plates 41 erected on the base 18 and carried on one end of the base 18, and the opening of the reflecting mirror is directed to the other end of the base 18. At the other end of the base 18, a first light guide tube 13 a constituting a part of the rod 13 is held by a rod holding plate 43 erected on the base 18, with one end surface facing the light source 11. It is supported. Further, a color wheel 12 is interposed on the base 18 across the optical axis connecting the light source 11 and the first light guide tube. The color wheel 12 is configured as a disk in which optical filters of red (R), blue (B), and green (G) are arranged in the circumferential direction, and is a color erected on the base 18. The optical filter is pivotally supported by a rotation shaft of a drive motor (not shown) provided on the upper portion of the wheel holding plate 42, and the optical filters rotate so as to periodically intersect the optical axis. The color wheel 12 is not limited to having an RGB optical filter, but may have an RGBW (white) optical filter. A wheel is provided at the lower part of the base 18 and is configured to roll on the rail provided at the bottom of the housing 45 in the optical axis direction of the rod 13. The base 18 is driven by converting a rotary motion into a linear motion by engaging a worm gear attached to the rotary shaft of the base drive motor 22a, which is a pulse motor, with a rack of helical teeth fixed to the base 18 side. Do it.

  The first light guide tube 13a and the second light guide tube 13b are formed of two light guide tubes having an inner surface as a reflection surface by a reflection film such as an aluminum vapor deposition film, and whose inner and outer cross-sectional shapes are rectangular. In the insertion portion between the first light guide tube 13a and the second light guide tube 13b, the internal cross-sectional dimension of the first light guide tube 13a and the external cross-sectional dimension of the second light guide tube 13b are substantially the same. The first light guide tube 13a provided on the base 18 is slidably fitted to the second light guide tube 13b fixed to the optical unit holder 44 fixed to the housing 45. I'm allowed. Since the cross-sectional normal dimension of the first light guide tube 13a on the light source side is larger than that of the second light guide tube 13b, the loss of the light collected by the reflecting mirror of the light source 11 is suppressed and the rod 13 is efficiently formed. It can be made incident.

  The optical unit holder 44 includes a relay lens unit 14 that collects light emitted from the second light guide tube 13b, an optical aperture 15 that is electrically opened and closed and functions as an open aperture of the relay lens unit 14, and a relay lens unit 14 The image display element 16 that converts the light collected by the light into image display light and the projection optical system 17 that projects the image display light onto the projection surface outside the projector are fixed in this order with their optical axes aligned. ing. The video display element 16 is a light modulation element such as a DMD or a liquid crystal display panel, but is not limited thereto. The projection optical system 17 includes a projection lens and a mechanism that drives a part of the projection lens.

  The shape of the exit surface of the second light guide tube 13b is rectangular, and the aspect ratio is 4 to 3 or 16 to 9 in accordance with the video display element 16. Thereby, when the substantially uniform light emitted from the rod irradiates the image display element 16 via the relay lens portion 14, it can be irradiated substantially uniformly according to the shape of the image display element 16. Therefore, the light irradiated outside the range of the video display element 16 is reduced, and the loss of light as a projector can be suppressed. The cross-sectional shape of the rod 13 including the insertion portion is rectangular as a whole. For example, the cross-sectional shape from the incident surface to the insertion portion is circular, and smoothly becomes a rectangle toward the tip. May be.

  FIG. 3 is an explanatory diagram showing how the light source image is divided by internal reflection of the rod. The rods 131 and 132 represent a short rod and a long rod, respectively. The dotted optical paths 31a and 31b, the dashed dotted optical paths 32a and 32b, and the dashed dotted optical paths 33a and 33b respectively represent optical paths of light incident on the rods 131 and 132 at a fixed angle from a fixed portion of the light source 11, and a light source image 34a. , 34b schematically represent light source images when the light emitted from the respective rods 131, 132 is condensed. In FIG. 3A, the optical paths 31a, 32a, and 33a are reflected twice, once, and 0 times on the inner surface of the short rod 131, respectively, whereas in FIG. 3B, the optical paths 31b, 32b, and 33b are long. Reflected on the inner surface of the rod 132 5 times, 3 times and 1 time respectively. In the case of the long rod 132, the number of divisions of the light source image is increased by increasing the number of reflections on the inner surface as compared with the case of the short rod 131, and the illuminance distribution of the light condensed on the video display element becomes more uniform. On the other hand, when the number of reflections on the inner surface of the rod increases, the luminance distribution of the light emitted from the rod improves, whereas the reflection loss increases and the luminance decreases. Therefore, a longer rod can be used to improve the luminance distribution even when the luminance related to the light emitted from the rod is lowered, and a shorter rod can be used to increase the luminance even if the luminance distribution is deteriorated.

  Referring back to FIGS. 1 and 2, the white light emitted from the light source 11 passes through a filter of any one of RGB colors, and RGB single color lights are generated in a time division manner. The RGB single-color lights thus generated are incident on the rod 13 and are repeatedly reflected on the inner surface of the rod, thereby increasing the uniformity of the light flux and exiting from the rod 13. The R, G, and B monochromatic lights emitted from the rod 13 are condensed on the image display element 16 in a time-sharing manner while the opening of the optical diaphragm 15 is adjusted while being relayed by the relay lens unit 14. The video display element 16 is controlled by the video display element control unit 23 to convert incident light into video display light. The RGB monochromatic light incident on the video display element 16 in a time division manner is converted into a time division RGB video display light, and is projected onto a projection surface such as an external screen by the projection optical system 17 to give a color image to the user. Be recognized.

  The projector includes a control unit 24 including a CPU that performs calculation, a ROM that stores information such as programs and tables necessary for the calculation, and a RAM that stores temporarily generated information. The video signal input to the video input unit 25 is given to the control unit 24, and the control unit 24 gives a signal synchronized with the video signal field frequency to the color wheel driving unit 21. The color wheel drive unit 21 rotates the color wheel 12 in synchronization with the video signal field frequency. The control unit 24 sequentially determines which of the RGB monochromatic lights is transmitted by the color wheel 12, and gives the video of each color to the video display element control unit 23 based on the video signal input from the video input unit 25. With this configuration, the video display element 16 can convert each color light separately generated by the color wheel 12 into video display light based on the same color video signal.

  The luminance selection or the luminance distribution uniformity selection related to the video display light and the projected video is set in the projection mode setting switch 26 connected to the control unit 24, and the control unit 24 reads the switching direction of the projection mode setting switch 26. . Projection modes include a high luminance mode that emphasizes high brightness so that it is suitable for viewing in a bright room, and a high brightness that emphasizes good brightness distribution and high contrast so that it is suitable for viewing in a dark room. There is a contrast mode. When the high luminance mode is set, the control unit 24 opens the optical aperture 15 and drives the base 18 to shorten the rod length, and also increases the luminance of the light emitted from the rod 13. When the high contrast mode is set, the optical diaphragm 15 is narrowed and the base 18 is driven to extend the rod length, thereby improving the luminance distribution of the light emitted from the rod 13. At this time, when the optical diaphragm 15 is stopped, unnecessary light such as scattered light generated inside the relay lens unit 14 is blocked, and the contrast of the projected image is improved. The drive distance of the base 18 is controlled by counting the number of drive pulses of the base drive motor 22a.

  FIG. 4 is a schematic diagram schematically showing the relationship between the optical path and the diaphragm of the projector according to the first embodiment. Light emitted from the light source 11 passes through the color wheel 12 and enters the rod 13. The light emitted from the rod 13 is condensed on the image display element 16 through the relay lens unit 14 and the optical diaphragm 15. In FIG. 4A, the optical path when the optical aperture 15 is opened is shown by a solid line, and in FIG. 4B, the optical path when the optical aperture 15 is stopped is shown by a solid line. The black arrow in FIG. 4B indicates the direction in which the rod 13 is extended while maintaining the positional relationship among the first light guide tube 13 a, the color wheel 12, and the light source 11. When the optical diaphragm 15 is stopped in FIG. 4B, among the light beams that enter the rod 13 from the light source 11 and are repeatedly reflected from the inner surface of the rod 13 and emitted from the rod 13, the number of reflections on the inner surface of the rod 13 is large. The component is blocked by the optical diaphragm 15. In this case, by extending the rod 13 in the direction of the black arrow, the number of reflections on the inner surface of the rod 13 is about the same as in the case of FIG. Can be.

  FIG. 5 is a flowchart of a procedure for controlling the base 18 and the optical aperture 15 according to the setting of the projection mode. The following processing is executed according to a control program stored in the control unit 24 in advance. The current projection mode is stored in the RAM in the initial setting of the control unit 24, and the control unit 24 compares the setting instruction by the projection mode setting switch 26 with the stored projection mode, and instructs the setting of the projection mode. It is determined whether or not has been changed (S11). When it is determined that there is no change in the projection mode setting instruction (S11: NO), the control unit 24 stands by without performing anything, and when it is determined that the setting instruction has been changed (S11: YES) It is determined whether or not the projection mode is a high luminance mode (S12). If the current mode is the high luminance mode (S12: YES), the control unit 24 starts the pulse drive of the base drive motor 22a to drive the optical stop 15 to the stop (S13) and drive the base 18 in the extending direction of the rod 13. (S14). The control unit 24 determines whether or not the number of drive pulses of the base drive motor 22a has reached a predetermined number (S15). If it is determined that the number has not reached (S15: NO), the control unit 24 waits without doing anything (S15). When it is determined that the number of drive pulses of the base drive motor 22a has reached a predetermined number (S15: YES), the control unit 24 stops driving the base 18 (S16), and the current projection mode stored in the RAM is determined. Update (S17). In step S12, when the current mode is not the high luminance mode but the high contrast mode (S12: NO), the control unit 24 opens the optical aperture 15 (S18), and the base is driven to drive the base 18 in the shortening direction of the rod 13. The pulse drive of the motor 22a is started (S19). The control unit 24 determines whether or not the number of drive pulses of the base drive motor 22a has reached a predetermined number (S20). If it is determined that the number has not reached (S20: NO), the control unit 24 waits without doing anything (S20). ). When it is determined that the number of drive pulses of the base drive motor 22a has reached a predetermined number (S20: YES), the control unit 24 stops driving the base 18 (S16), and the current projection mode stored in the RAM is determined. Update (S17).

In the projector according to the first embodiment, time-division RGB video display light is projected to the outside by the projection unit. The control unit controls the opening degree of the optical diaphragm according to the setting of the projection mode, and performs control for driving the base in the direction in which the rod is slid. In the high brightness mode, the optical aperture is opened to allow the maximum luminous flux to pass, and the rod length is shortened to reduce the number of reflections on the inner surface of the rod, thereby suppressing reflection loss and reducing the light emitted from the rod. High brightness. In the high contrast mode, the optical diaphragm is squeezed to reduce the luminance while blocking unnecessary light such as scattered light to improve the contrast, and the rod length is extended to increase the number of reflections on the inner surface of the rod. In the high contrast mode, since the number of light source image divisions of the light emitted from the rod increases, the luminance distribution of the light emitted from the rod becomes more uniform than in the high luminance mode.
Accordingly, it is possible to project the color image display light appropriately adjusted in luminance, contrast, and luminance distribution.

  In addition, the aspect ratio of the cross-sectional shape of the substantially uniform light beam emitted from the rod for each of the colors is substantially the same as the aspect ratio of the video display element, so that the video display element can be irradiated substantially uniformly according to the shape. The loss due to irradiation outside the range of the image display element can be reduced.

(Embodiment 2)
FIG. 6 is a rear perspective view schematically showing the rod selection mechanism of the projector according to the second embodiment of the present invention. In FIG. 6, a rod holding plate 43 b erected on the housing 45 is interposed between the color wheel 12 and the relay lens portion 14 in the optical unit holder 44. The light source holding plate 41 and the color wheel holding plate 42 are also erected on the housing 45 without the base 18 interposed therebetween. A pulse motor is provided on the upper portion of the rod holding plate 43b. A rod holding member 51 is pivotally supported on a rotation shaft of the pulse motor, and glass rods 13c are provided at both ends of the rod holding member 51. And the hollow rod 13d is clamped. The light guide path diameter of the glass rod 13c is equal to the inner diameter of the hollow rod 13d. The rod is selected by rotating the rod holding member 51 by 180 degrees with the pulse motor while counting the drive pulses of the pulse motor under the control of the control unit 24. In the case of the high luminance mode, the glass rod 13c is selected, and in the case of the high contrast mode, the hollow rod 13d is selected, and the optical axis of each rod and the optical axis of the light source 11 are selectively aligned. Position it. The light emitted from the light source 11 is transmitted through the color wheel 12, is incident on the hollow rod 13d or the glass rod 13c, and is repeatedly reflected inside the rod, so that the uniformity of the light flux is increased and is emitted from each rod. The light emitted from the rod enters the relay lens unit 14 in the optical unit holder 44.

  FIG. 7 is an explanatory diagram showing how the light source image is divided by internal reflection of the rod. The dotted optical paths 61a and 61b, the dashed-dotted optical paths 62a and 62b, and the dashed-dotted optical paths 63a and 63b represent optical paths of light incident on the glass rod 13c and the hollow rod 13d, respectively, at a certain angle from a certain part of the light source 11. The light source images 64a and 64b schematically represent light source images when the light emitted from the glass rod 13c and the hollow rod 13d is condensed, respectively. Here again, the light guide path diameter of the glass rod 13c is equal to the inner diameter of the hollow rod 13d. In FIG. 7A, the optical paths 61a, 62a, and 63a are reflected twice, once, and 0 times inside the glass rod 13c, respectively, whereas in FIG. 7B, the optical paths 61b, 62b, and 63b are hollow. Reflected on the inner surface of the rod 13d five times, three times and once, respectively. In the case of the hollow rod 13d, the number of divisions of the light source image is increased by increasing the number of reflections on the inner surface as compared with the case of the glass rod 13c, and the illuminance distribution of the light condensed on the video display element 16 becomes more uniform.

In the projector according to Embodiment 2, the control unit controls the opening of the optical aperture according to the setting of the projection mode, and selectively positions the solid glass rod or the hollow rod at a predetermined position. In the high-brightness mode, the optical aperture is opened to allow the maximum luminous flux to pass, and the glass rod is selected to reduce the number of reflections inside the rod, thereby suppressing reflection loss and reducing the light emitted from the rod. High brightness. In the high contrast mode, the optical diaphragm is squeezed to reduce the luminance while blocking unnecessary light such as scattered light to improve the contrast, and the hollow rod is selected to increase the number of reflections on the inner surface of the rod. In the high contrast mode, since the number of light source image divisions of the light emitted from the rod increases, the luminance distribution of the light emitted from the rod becomes more uniform than in the high luminance mode.
Accordingly, it is possible to project color image display light in which brightness, contrast, and brightness distribution are appropriately adjusted to the outside.

  In the second embodiment, the glass rod or the hollow rod is selectively positioned at a predetermined position. However, the rod to be selected is not limited to these, and the refractive index or the diameter of the light guide path. May be configured to select one from two rod-shaped light guides having different diameters or to select one from two light guide tubes having different inner diameters. When one of the two rod-shaped light guides is selected, in the high luminance mode, a rod having a higher refractive index and a larger light guide path diameter is selected to reduce the number of reflections inside the rod, and the high contrast mode is selected. In this case, a rod having a lower refractive index and a smaller light guide path diameter is selected to increase the number of reflections inside the rod. When selecting one of the two light guide tubes, select a rod with a larger inner diameter in the high luminance mode to reduce the number of reflections inside the rod, and a rod with a smaller inner diameter in the high contrast mode. Select to increase the number of reflections inside the rod. By selecting as described above, the number of reflections inside the rod is reduced in the high luminance mode, and the reflection loss is suppressed to increase the luminance, whereas in the high contrast mode, the number of reflections inside the rod is reduced. Increasing, the light becomes more uniform.

  FIG. 7C is a diagram showing a state in which the light source image is divided by reflection of the inner surface of the hollow rod 13e in which the inner diameter of the hollow rod 13d in FIG. It shows that the number of reflections on the inner surface of the rod can be reduced by reducing the inner diameter of the hollow rod, thereby reducing reflection loss. In this case, in order to avoid that the light source image 64c is enlarged and the light irradiated outside the range of the video display element 16 is increased, the size of the exit of the hollow rod 13e and the size of the exit of the hollow rod 13d are It is also possible to make them coincide and taper from the exit to the entrance.

  Since the configuration, operation, and effects other than the rod selection mechanism of the projector according to the second embodiment are the same as the configuration, operation, and effect of the projector according to the first embodiment, the same reference numerals are used for corresponding portions. A detailed description thereof will be omitted.

  In the first and second embodiments, the examples have been described with respect to the two projection modes of the high luminance mode and the high contrast mode. However, the projection mode may be configured to be set in multiple stages. In this case, the projection mode setting switch can set each stage of the projection mode, and in the first embodiment, the opening of the optical diaphragm and the moving position of the base according to each stage of the set projection mode. Is determined in stages. Further, in the second embodiment, the rod holding member is, for example, a disc shape, and the number of internal reflections is different step by step on the circumference of the rod holding member. The rods are held at equal intervals in the order of the steps, and the opening of the optical diaphragm and the rotation angle of the rod holding member are determined stepwise according to each step of the set projection mode.

It is a block diagram which shows the structure of the projector which concerns on Embodiment 1 of this invention. It is a perspective view of a side view schematically showing a mechanism for slidingly extending and contracting a rod. It is explanatory drawing which shows a mode that a light source image is divided | segmented by the internal reflection of a rod. 3 is a schematic diagram schematically showing a relationship between an optical path and a diaphragm of the projector according to Embodiment 1. FIG. It is a flowchart about the procedure which controls a base and an optical aperture according to the setting of projection mode. It is a perspective view of the back view which shows schematically the rod selection mechanism of the projector which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows a mode that a light source image is divided | segmented by the internal reflection of a rod. It is a schematic diagram which shows roughly the relationship between the optical path of a conventional projector, and an aperture stop.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Color wheel 13, 131, 132 Rod 13a 1st light guide tube 13b 2nd light guide tube 13c Glass rod 13d, 13e Hollow rod 14 Relay lens part 15 Optical aperture 16 Image | video display element 17 Projection optical system 18 Base 21 Color wheel drive unit 22a Base drive motor 23 Video display element control unit 24 Control unit 25 Video input unit 26 Projection mode setting switches 34a and 34b Light source image 41 Light source holding plate 42 Color wheel holding plate 43 and 43b Rod holding plate 44 Optical unit Holder 45 Housing 51 Rod holding member 64a, 64b, 64c Light source image

Claims (4)

In a projector comprising a light source, a tubular rod having an inner surface as a reflection surface and an end surface facing the light source, and image display means for converting light emitted from the rod into image display light and emitting the image display light,
The rod is slidably inserted into a first light guide tube provided on the light source side and a second light guide tube fixed on the image display means side,
A base supporting the light source and the first light guide tube;
Base driving means for driving the base in a direction in which the first light guide tube slides with respect to the second light guide tube;
Receiving means for receiving an instruction relating to sliding of the rod;
A projector comprising: control means for controlling the base drive means so that the position of the base changes according to the instruction content received by the reception means. In a projector comprising a light source, a light guide rod having a predetermined length with an end face facing the light source, and video display means for converting light from the light source into video display light and emitting the same.
The rod is one of a light guide tube having an inner surface as a reflection surface and different inner diameters and a rod-shaped light guide having different refractive indexes or different light guide path diameters, and has two or more different types of rods.
Selection means for selectively positioning any one of the rods at a predetermined position in an optical path from the light source to the image display means;
Receiving means for receiving an instruction related to selection of the rod;
A projector comprising: control means for controlling the selection means so that any one of the rods is positioned at the predetermined position in accordance with the instruction content received by the reception means. Condensing means for condensing the light emitted from the rod on the image display means;
An optical diaphragm means for adjusting the aperture of the diaphragm with the light collecting means;
Projecting means for projecting the image display light to the outside,
The projector according to claim 1, wherein the control unit controls an opening degree of the optical aperture unit in accordance with the content of the instruction.   The projector according to claim 3, wherein the shape of the exit surface of the rod and the shape of the image display means are substantially similar.

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