JP2011158657A - Image projection unit and projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projection unit and a projection type image display device in which an interchangeable lens having a different back focal length can be used. <P>SOLUTION: The image projection unit includes a plurality of liquid crystal panels 13R, 13G and 13B that modulate a plurality of color light beams, respectively; a color-compositing prism 14 that by compositing the plurality of color light beams modulated by the plurality of liquid crystal panels; the interchangeable lens 30 that projects the color light composited by the color-compositing prism; a shifting unit 15 to which the interchangeable lens having different a back focal length is mounted freely; and a lens holder 16 that is configured where a correction lens 50 for correcting the back focus length is removably mounted, according to the back focal length of the interchangeable lens mounted to the shifting unit. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image projection unit and a projection type image display device.

  2. Description of the Related Art There is known a lens interchangeable projector (projection type image display device) that can be used by replacing a projection lens according to the use environment.

  In this type of projector, the optimum specifications differ depending on the panel dimensions, resolution, product dimensions, product price, etc., and therefore the mounting specifications and operation specifications (optical specifications, electrical specifications, etc.) of the interchangeable lens differ for each model. For example, the mounting specifications are determined according to the means for mounting with the interchangeable lens, the optical specifications are determined according to the optical aberration characteristics at the time of keystone correction, etc., and the electrical specifications are determined according to the driving voltage of the electric zoom / focus, etc. Determined.

  In particular, in this type of projector, an optimal aberration state can be obtained when using an interchangeable lens having a predetermined back focus length (the length from the apex of the rearmost lens accommodated in the interchangeable lens to the rear focal point). Optical specifications have been determined. When the optimal aberration state is not obtained, the optical performance of the interchangeable lens is not sufficiently exhibited, the projected image becomes unclear, and the projector cannot be used.

  For this reason, conventional projectors cannot use interchangeable lenses with different back focus lengths in an optimal aberration state. However, the user may desire to use an interchangeable lens having a different back focus length by attaching it to his projector.

  Accordingly, the present invention is intended to provide an image projection unit and a projection-type image display device that enable the use of interchangeable lenses having different back focus lengths.

  According to an aspect of the present invention, a plurality of image display elements that respectively modulate a plurality of color lights, a prism type element that combines a plurality of color lights modulated by the plurality of image display elements, and a prism type element. The back focus length is corrected according to the interchangeable lens that projects the colored light, the interchangeable lens mount that allows the interchangeable lens with a different back focus length to be mounted, and the back focus length of the interchangeable lens that is mounted on the interchangeable lens mount. There is provided an image projection unit including a correction lens mounting portion for detachably mounting a correction lens to be attached.

  According to such a configuration, in the image projection unit, an interchangeable lens having a different back focus length can be attached, and a correction lens for correcting the back focus length is detachably attached according to the back focus length of the attached interchangeable lens. It is done. Thereby, according to the optical specification of the image projection unit, an interchangeable lens having a different back focus length can be used by attaching and detaching the correction lens so as to obtain an optimal aberration state.

  The image projection unit may further include a lens moving unit for translating the interchangeable lens in a direction orthogonal to the optical axis, and the lens moving unit may be provided with an interchangeable lens mounting unit and a correction lens mounting unit. .

  The correction lens mounting portion may be provided between the exit surface of the prism type element and the entrance surface of the interchangeable lens.

  An opening that allows the correction lens to be manually attached or detached may be provided on the front surface of the correction lens attachment portion in a state where no interchangeable lens is attached.

  The correction lens may be a flat lens, a spherical lens, or an aspheric lens.

  According to another aspect of the present invention, there is provided a projection-type image display device comprising the above-described image projection unit and an illumination optical system that decomposes illumination light into a plurality of color lights and irradiates a plurality of image display elements. Is done.

  As described above, according to the present invention, it is possible to provide an image projection unit and a projection-type image display device that enable the use of interchangeable lenses having different back focus lengths.

It is a figure which shows the structure of the projector which concerns on embodiment of this invention. It is a schematic diagram which shows the attachment method of the interchangeable lens with respect to a projector main body. It is a perspective view which shows the attachment procedure of the correction lens with respect to a lens holder. It is a perspective view which shows the shift unit before correction | amendment lens attachment. It is a perspective view which shows the shift unit after correction lens attachment. It is sectional drawing which shows the cross section along 6-6 line shown in FIG. It is a perspective view which shows the shift unit after A type interchangeable lens attachment. It is sectional drawing which shows the 7-7 cross section shown in FIG. It is a perspective view which shows the shift unit after C-type interchangeable lens attachment. It is sectional drawing which shows the cross section along 10-10 line shown in FIG.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[1. Configuration of Projector 1]
First, the configuration of a projector 1 (projection type image display device) according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the projector 1 includes a light source 11 (lamp 111, reflector 112), illumination optical system 12, three liquid crystal panels 13R, 13G, and 13B (image display elements), a color synthesis prism 14 (prism type element). ) And a shift unit 15 (lens moving unit). The projector 1 is attached to the projector main body 10 directly or via a lens adapter 40 (hereinafter also referred to as an adapter 40), and the projector main body 10 via a lens holder 16 (correction lens mounting portion). A correction lens 50 is attached.

  Here, the shift unit 15 functions alone or in combination with the adapter 40 as an interchangeable lens mounting portion. The interchangeable lens 30, the adapter 40, and the correction lens 50 are generic names of various interchangeable lenses 30A, 30B, and 30C, adapters 40B and 40C, and correction lenses 50A and 50B, which will be described later.

  In the projector 1, the white light emitted from the light source 11 is illuminated and condensed and is incident on the three liquid crystal panels 13R, 13G, and 13B. The white light is condensed by the illumination optical lens 121 and then decomposed into three color lights of red, green, and blue by the color separation element in the illumination optical system 12, and the decomposed three color light is converted into the corresponding liquid crystal panel 13R, Incident on 13G and 13B.

  The color separation element has first and second dichroic mirrors 122 and 123 and first to third folding mirrors 124 to 126. The first dichroic mirror 122 transmits red light and reflects green light and blue light. In the second dichroic mirror 123, the blue light reflected by the first dichroic mirror is transmitted, and the green light is reflected and enters the liquid crystal panel 13G. In the first folding mirror 124, the red light transmitted through the first dichroic mirror 122 is reflected and enters the liquid crystal panel 13R. The second and third folding mirrors 125 and 126 reflect the blue light transmitted through the second dichroic mirror 123 and enter the liquid crystal panel 13B.

  The three liquid crystal panels 13R, 13G, and 13B spatially modulate incident light based on a video signal applied as an electrical signal. Light emitted from the liquid crystal panels 13R, 13G, and 13B is combined by the color combining prism 14 and enters the interchangeable lens 30. Then, the images of the liquid crystal panels 13R, 13G, and 13B are synthesized by the interchangeable lens 30 and projected and output, and projected onto a screen or the like.

  The interchangeable lens 30 is attached to the projector main body 10 via the shift unit 15 disposed on the emission side of the color synthesis prism 14. The shift unit 15 has a mechanism for shifting the interchangeable lens 30 in a direction orthogonal to the optical axis. The interchangeable lens 30 can be attached to the shift unit 15 directly or via a corresponding adapter 40 according to the attachment specification of the interchangeable lens 30. In addition, the correction lens 50 can be attached to the shift unit 15 via the lens holder 16 in accordance with the optical specifications of the interchangeable lens 30.

  Here, the correction lens 50 is attached to obtain an optimal aberration state when the interchangeable lens 30 having a back focus length other than a predetermined back focus length (standard back focus length) is used. As the correction lens 50, any of a flat lens, a spherical lens, and an aspheric lens may be applied.

  The interchangeable lens 30 or the adapter 40 is provided with connectors 31 and 41, and the shift unit 15 is provided with a socket 151 corresponding to the connectors 31 and 41. The connectors 31 and 41 are used for transmitting identification information indicating the operation specifications of the interchangeable lens 30 to the projector main body 10. The connectors 31 and 41 may be used to supply drive power to the drive motor 32 of the interchangeable lens 30 having an electric zoom / focus function.

  The projector 1 further includes an identification information detection unit 17, a power supply unit 18, an operation unit 19, a display unit 20, and a control unit 21. The identification information detection unit 17 detects the identification information of the interchangeable lens 30 through the connectors 31 and 41. The power supply unit 18 supplies drive power through the connectors 31 and 41 to the drive motor 32 of the interchangeable lens 30 having an electric zoom / focus function. The operation unit 19 includes operation elements such as buttons and receives operation inputs from the user. The display unit 20 displays an operation menu or the like on a display panel or screen. The control unit 21 includes, for example, a CPU, a ROM, a RAM, and the like, and controls the overall operation of the projector 1 through execution of a program. The control unit 21 controls the operation of the entire projector 1 according to the operation specification indicated by the identification information of the interchangeable lens 30.

[2. Mounting method of interchangeable lens 30]
Next, a method for attaching the interchangeable lens 30 to the projector body 10 will be described with reference to FIG.

  FIG. 2 schematically shows a method for attaching the interchangeable lens 30. As shown in FIG. 2, the interchangeable lens 30 has different mounting specifications depending on the model. For this reason, the interchangeable lens 30 is attached to the projector main body 10 (shift unit 15) directly or via the adapter 40 according to the attachment specification.

  For example, since the A-type interchangeable lens 30 </ b> A has an installation specification that matches the shift unit 15, it is directly attached to the front side of the shift unit 15. Further, since the B-type and C-type interchangeable lenses 30B and 30C do not have the mounting specifications suitable for the shift unit 15, the front surfaces of the shift unit 15 are respectively connected via the B-type and C-type adapters 40B and 40C. Mounted on the side.

  In addition, the interchangeable lens 30 has different operation specifications (optical specifications and electrical specifications) depending on the model. Therefore, the interchangeable lens 30 transmits identification information indicating the operation specifications of the interchangeable lens 30 to the projector body 10. In the projector body 10, the control unit 21 controls the overall operation of the projector 1 based on the operation specifications of the interchangeable lens 30.

  For example, in the A type interchangeable lens 30A, the connector 31 provided on the interchangeable lens 30A itself is connected to the socket 151 of the shift unit 15 to transmit the identification information. In the B-type and C-type interchangeable lenses 30B and 30C, the connector 41 provided on the B-type and C-type adapters 40B and 40C attached to the interchangeable lenses 30B and 30C is connected to the socket 151 of the shift unit 15 for identification information. Is transmitted. Identification information of the B-type and C-type interchangeable lenses 30B and 30C is held in the B-type and C-type adapters 40B and 40C. The connectors 31 and 41 are used for detection of the mounting state of the interchangeable lens 30, detection of the type of the interchangeable lens 30, supply of drive power, signal transmission for controlling the interchangeable lens 30, and the like.

  Here, the interchangeable lens 30 has different back focus lengths depending on the model. On the other hand, the optical specifications of the projector main body 10 are determined so that an optimal aberration state can be obtained when the interchangeable lens 30 having a standard back focus length is used. Therefore, the interchangeable lens 30 is attached to the projector main body 10 (shift unit 15) with the correction lens 50 being attached and detached according to the back focus length.

  For example, when the C-type interchangeable lens 30C having a standard back focus length is used, the C-type interchangeable lens 30C is attached to the front side of the shift unit 15. On the other hand, when the A type and B type interchangeable lenses 30A and 30B having a back focus length different from the standard back focus length are used, the A type and B type interchangeable lenses 30A and 30B are attached to the front side of the shift unit 15. At the same time, the corresponding correction lenses 50 </ b> A and 50 </ b> B are attached to the rear surface side of the shift unit 15.

  Here, the correction lenses 50A and 50B corresponding to the A-type and B-type interchangeable lenses 30A and 30B are attached so as to correct the back focus length of each of the interchangeable lenses 30A and 50B to the standard back focus length. The standard back focus length is defined as the length from the top of the last lens accommodated in the interchangeable lens 30 to the rear focal point. In FIG. 2, only the last lens is shown among the lenses housed in the interchangeable lens 30.

[3. Specific example of mounting method]
4 to 10 show specific examples of a method for attaching the interchangeable lens 30 to the shift unit 15. FIG. 3 shows a procedure for attaching the correction lens 50 to the lens holder 16. 4 and 5 each show the shift unit 15 before and after the correction lens 50 is attached.

(Correction lens 50)
As shown in FIG. 3, the correction lens 50 is fixed to the lens ring 51. In the lens ring 51, a circular opening 511 for fixing the correction lens 50 is provided at the center, and a flange 512 for attaching the lens ring 51 to the lens holder 16 is provided at the periphery. The flange 512 includes an arc-shaped front piece 512a and a protruding rear piece 512b. The four front pieces 512a and the four rear pieces 512b form a predetermined step in the front-rear direction of the flange 512 (the depth direction on the paper). It is formed alternately. The lens ring 51 has a first mark 513 indicating one of the rear piece 512b.

  The lens holder 16 includes a substantially ring-shaped attachment member 161 and a substantially semicircular arch-shaped fixing member 162 protruding from the upper half periphery of the attachment member 161. The attachment member 161 is provided with an opening 163 in the center for attaching the correction lens 50 via the lens ring 51. The fixing member 162 is provided with three screw holes 164 for inserting fixing screws.

  The periphery of the opening 163 includes a first arc portion 165a having substantially the same radius as the flange 512, and a second arc portion 165b having substantially the same radius as the lens ring 51 excluding the flange 512. One arc portion 165a and four second arc portions 165b are alternately formed. The peripheral edge of the opening 163 is formed with a member thickness corresponding to a step formed between the front piece 512a and the rear piece 512b of the lens ring 51. Further, the mounting member 161 includes a second mark 166 indicating one of the first arc portions 165a, and a third mark 167 indicating a position of a predetermined separation distance from the second mark 166 along the opening 163. Is attached.

  When the correction lens 50 is attached, the lens ring 51 is disposed in the opening 163 of the lens holder 16 so that the first mark 513 overlaps the second mark 166, and the four rear surface pieces 512b are the four first arc portions. 165a is engaged. Then, the lens ring 51 is rotated in the circumferential direction (clockwise in the example shown in FIG. 3) so that the first mark 513 overlaps the third mark 167. Here, when the lens ring 51 is rotated, the four second arc portions 165b of the lens holder 16 are sandwiched between the corresponding front piece 512a and the rear piece 512b of the lens ring 51, and the lens holder A lens ring 51 is attached to 16. Accordingly, the correction lens 50 can be easily attached to the lens holder 16 without using a tool.

(Shift unit 15)
FIG. 4 shows the shift unit 15 with the lens holder 16 attached to the rear side. As shown in FIG. 4, the shift unit 15 is fixed to the fixed frame 152 fixed to the front surface of the projector body 10, the shift frame 153 slidably supported with respect to the fixed frame 152, and the shift frame 153. A support frame 154 for supporting the interchangeable lens 30 and a shift mechanism 155 for shifting the shift frame 153 are included.

  The fixed frame 152 is an opening through which the interchangeable lens 30 is inserted, and an opening 152a covered by the lens holder 16 attached to the rear surface side is provided in the center, and four screw holes 152b through which the fixing screws are inserted are provided. It is provided at the corner (two are shown in the figure). The shift frame 153 has an opening 153a through which the interchangeable lens 30 is inserted at the center. The support frame 154 is provided with a circular opening 154a for inserting the interchangeable lens 30 in the center, and screw holes 154b for inserting mounting screws are provided in four corners. The connector 31 of the interchangeable lens 30 or the adapter 40 is provided. , 41 are connected to one end of the socket 151. The shift mechanism 155 is provided with a drive mechanism including a motor 155a, a gear 155b, a feed screw 155c, and the like.

  In the shift unit 15, the interchangeable lens 30 inserted through the three openings 152a, 153a, 154a is attached to the support frame 154 via attachment screws. Then, by shifting the shift frame 153 with respect to the fixed frame 152, the interchangeable lens 30 is shifted in the vertical direction (vertical direction with respect to the drawing) perpendicular to the optical axis, and the support frame 154 is shifted horizontally. Shifted in the direction (left-right direction with respect to the drawing). In the shift mechanism 155, for example, the shift frame 153 is shifted by controlling the drive mechanism in accordance with a control signal supplied from the control unit 21.

  FIG. 5 shows the shift unit 15 in a state where the correction lens 50 is attached via the lens holder 16. As shown in FIG. 4, two openings 153 a and 154 a for inserting the interchangeable lens 30 are provided on the front side of the shift unit 15. Here, the openings 153a and 154a have dimensions such that the lens ring 51 held by the user can be inserted. Therefore, when the interchangeable lens 30 is attached, the user places the correction lens 50 fixed to the lens ring 51 on the front side of the lens holder 16 through the openings 153a and 154a, and follows the procedure described in FIG. Can be detachably attached.

  FIG. 6 shows a cross section along line 6-6 shown in FIG. As shown in FIG. 6, the shift unit 15 is disposed on the exit side (left side in FIG. 6) of the color synthesis prism 14, and the lens holder 16 is disposed on the rear side (right side in FIG. 6) of the shift unit 15. Is installed. In the shift unit 15, a fixed frame 152, a shift frame 153, and a support frame 154 are arranged in this order from the color synthesis prism 14 side. In FIG. 6, the interchangeable lens 30 is indicated by a two-dot chain line. As shown in FIG. 6, the correction lens 50 is disposed between the exit surface of the color synthesis prism 14 and the entrance surface of the interchangeable lens 30, so that the apex of the last lens (not shown) accommodated in the interchangeable lens 30. Is corrected to the standard back focus length.

(Example of mounting the interchangeable lens 30)
FIGS. 7 to 10 show attachment states of A-type and C-type interchangeable lenses 30 </ b> A and 30 </ b> C as attachment examples of the interchangeable lens 30.

  First, FIG. 7 shows the shift unit 15 after the A-type interchangeable lens 30A is attached, and FIG. 8 shows a cross section taken along line 8-8 (optical axis) shown in FIG. In FIG. 8, details in the lens barrel 33 are omitted.

  As shown in FIGS. 7 and 8, the A-type interchangeable lens 30 </ b> A includes a lens barrel 33 and an attachment frame 34 for attaching the lens barrel 33 to the shift unit 15. The lens barrel 33 accommodates one or more lenses (not shown), a lens cover 331 is provided at the front end, a mount 332 is provided at the rear end, and the drive motor 32 is fixed to the periphery via a fixed frame 333. Has been. The attachment frame 34 is provided with four screw holes 341 (three are shown in the figure) for inserting attachment screws, and an opening 342 for inserting the lens barrel 33. It is provided in the center.

  The attachment frame 34 is provided with a holding plate 351 for holding a substrate (not shown) at one end. The holding plate 351 is provided with a substrate (not shown) on which the connector 31 is mounted, and a circuit pattern corresponding to the A-type interchangeable lens 30A is formed on the substrate.

  Here, as described above, the A-type interchangeable lens 30 </ b> A has a mounting specification that is compatible with the shift unit 15, so that it is directly mounted on the front side of the shift unit 15 without using the adapter 40. When attaching to the shift unit 15, the lens barrel 33 is inserted into the three openings 152 a, 153 a, 154 a of the shift unit 15. Then, mounting screws are inserted into the mounting frame 34 of the A-type interchangeable lens 30A and the screw holes 341 and 154b of the support frame 154. Further, the connector 31 of the A-type interchangeable lens 30 </ b> A is connected to the socket 151 of the shift unit 15.

  When the connector 31 of the A-type interchangeable lens 30A is connected to the socket 151, the identification information of the A-type interchangeable lens 30A is detected by the identification information detection unit 17, and the control unit 21 recognizes the mounting and type of the interchangeable lens 30A. . And the control part 21 controls the projector 1 whole according to the optical specification which identification information shows. Further, the control unit 21 determines whether the A-type interchangeable lens 30A has the electric zoom / focus function from the identification information, and displays the menu for performing the electric zoom / focus on the display unit 20 if applicable. When the execution of the electric zoom / focus is instructed, the drive motor 32 is driven and controlled with a 12V drive voltage in accordance with the electrical specification indicated by the identification information. The drive voltage is supplied from the power supply unit 18 through the connector 31 and transmitted to the drive motor 32 through a motor harness (not shown).

  Here, as described above, the A-type interchangeable lens 30A has a back focus length different from the standard back focus length. For this reason, as shown in FIG. 8, the A-type interchangeable lens 30A is attached to the front side of the shift unit 15, and the correction lens 50A corresponding to the A-type interchangeable lens 30A is attached to the rear side via the lens holder 16. It is done. Accordingly, by correcting the optical distance by the correction lens 50A, the A-type interchangeable lens 30A having a back focus length different from the standard back focus length can be used in an optimal aberration state.

  Next, FIG. 9 shows the shift unit 15 after the C-type interchangeable lens 30C is attached, and FIG. 10 shows a cross section along the line 10-10 (optical axis) shown in FIG. In FIG. 10, details in the lens barrel 33 are omitted.

  As shown in FIGS. 9 and 10, the C-type interchangeable lens 30C includes a lens barrel 33 and an attachment frame 34 for attaching the lens barrel 33 to another projector. The lens barrel 33 accommodates one or more lenses (not shown), a lens cover 331 is provided at the front end, and a mount 332 is provided at the rear end. The attachment frame 34 is provided with screw holes (not shown) for inserting attachment screws.

  The C-type adapter 40C includes an attachment cylinder 42 to which the C-type interchangeable lens 30C is attached, an attachment frame 43 to be attached to the shift unit 15, and a holding plate 441 that holds a substrate (not shown). The mounting cylinder 42 and the mounting frame 43 are formed in a shape suitable for mounting the C-type interchangeable lens 30C.

  The mounting cylinder 42 includes a semicircular arch cylindrical lower member 421 and a semicircular arch belt-shaped upper member 422. The lens barrel 33 is disposed between the lower member 421 and the upper member 422, and the mounting screw is inserted therethrough. Are provided at the base end of the arch of the lower member 421. The mounting frame 43 is a rectangular flat plate-like member. A circular opening 431 for inserting the lens barrel 33 is provided in the center, and a screw hole 432 for inserting a mounting screw has four corners (in the figure, 3 One is shown.). The mounting cylinder 42 protrudes from the mounting frame 43 so as to form an upper arch and a lower arch along the entire periphery of the circular opening 431 of the mounting frame 43.

  The holding plate 441 is supported by a support plate (not shown) protruding from one end of the front surface of the mounting frame 43. The holding plate 441 is provided with a substrate (not shown) on which the connector 41 and the motor harness socket 152 are mounted, and a circuit pattern corresponding to the C-type interchangeable lens 30C is formed on the substrate.

  Here, since the C-type interchangeable lens 30C has an attachment specification different from that of the shift unit 15, it is attached to the shift unit 15 via the C-type adapter 40C. In the state where the lens barrel 33 is inserted into the opening 431 of the mounting frame 43, the C-type interchangeable lens 30C has a screw hole (not shown) of the mounting frame 34 of the C-type interchangeable lens 30C and a screw hole (not shown) of the mounting cylinder 32. ) Is attached to the C-type adapter 40C.

  The C-type interchangeable lens 30C is attached to the shift unit 15 while being attached to the C-type adapter 40C. When attaching to the shift unit 15, the lens barrel 33 is inserted into the three openings 152 a, 153 a, 154 a of the shift unit 15. Then, mounting screws are inserted into the mounting frames 43 of the C-type adapter 40C and the screw holes 432 and 154b of the support frame 154 of the shift unit 15.

  Further, the connector 41 of the C-type adapter 40C is connected to the socket 151 of the shift unit 15. Further, a socket 151 (not shown) provided on the drive motor 32 of the C-type interchangeable lens 30C is connected to a socket 151 (not shown) of the C-type adapter 40C by a motor harness connector (not shown). Accordingly, the C-type interchangeable lens 30C having different installation specifications and operation specifications can be attached to the shift unit 15 via the C-type adapter 40C.

  When the connector 41 of the C-type adapter 40C is connected to the socket 151, the identification information of the C-type interchangeable lens 30C is detected by the identification information detection unit 17, and the control unit 21 recognizes the mounting and model of the interchangeable lens 30C. And the control part 21 controls the projector 1 whole according to the optical specification which identification information shows. Further, since the C-type interchangeable lens 30C does not have the electric zoom / focus function, the control unit 21 does not display a menu or the like for performing the electric zoom / focus on the display unit 20. Then, the control unit 21 does not perform drive control of the drive motor 32.

  Here, the C-type interchangeable lens 30C has a standard back focus length as described above. Therefore, as shown in FIG. 10, the C-type interchangeable lens 30 </ b> C is attached to the front side of the shift unit 15, but the correction lens 50 is not attached to the rear side. Thereby, the C-type interchangeable lens 30C having the standard back focus length can be used in an optimal aberration state.

  Since the B-type interchangeable lens 30B has an attachment specification different from that of the shift unit 15, the B-type interchangeable lens 30B is attached to the shift unit 15 via the B-type adapter 40B in the same manner as the C-type interchangeable lens 30C. The connector 41 of the B-type adapter 40B is connected to the socket 151 of the shift unit 15, and the socket 152 (not shown) provided on the drive motor 32 of the B-type interchangeable lens 30B and the socket 152 of the B-type adapter 40B are motor harnesses. Are connected by a connector (not shown).

  Furthermore, as described above, the B-type interchangeable lens 30B has a back focus length different from the standard back focus length. Therefore, similarly to the A-type interchangeable lens 30A, the B-type interchangeable lens 30B is attached to the front side of the shift unit 15, and the correction lens 50B corresponding to the B-type interchangeable lens 30B is disposed on the rear side via the lens holder 16. Mounted on. Thus, by correcting the optical distance by the correction lens 50B, the B-type interchangeable lens 30B having a back focus length different from the standard back focus length can be used in an optimal aberration state.

  As described above, according to the projector 1 according to the embodiment of the present invention, the interchangeable lens 30 having a different back focus length can be freely attached, and the correction lens 50 that corrects the back focus length of the attached interchangeable lens 30 is provided. Removably attached. Thereby, according to the optical specification of the image projection unit, the interchangeable lens 30 having a different back focus length can be used by attaching and detaching the correction lens 50 so as to obtain an optimal aberration state.

  Then, by preparing the correction lens 50 corresponding to the interchangeable lens 30 that has been released and having a different back focus length, or preparing the corresponding correction lens 50 together with the interchangeable lens 30 that is newly released, the correction lens 50 of the projector 1 is prepared. Can be used continuously.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Projector 10 Projector main body 11 Light source 12 Illumination optical system 13R, 13G, 13B Liquid crystal panel 14 Color composition prism 15 Shift unit 16 Lens holder 17 Identification information detection part 18 Power supply part 19 Operation part 20 Display part 21 Control part 30, 30A, 30B, 30C Interchangeable lens 31, 41 Connector 32 Drive motor 40, 40B, 40C Lens adapter 50, 50A, 50B Correction lens 51 Lens ring

Claims (6)

A plurality of image display elements each modulating a plurality of color lights;
A prism-type element that combines the plurality of color lights modulated by the plurality of image display elements;
An interchangeable lens that projects the color light synthesized by the prism type element;
An interchangeable lens mounting portion on which the interchangeable lens having a different back focus length can be freely mounted;
An image projection unit comprising: a correction lens mounting portion for detachably mounting a correction lens for correcting the back focus length according to a back focus length of the interchangeable lens mounted on the interchangeable lens mounting portion. A lens moving unit for translating the interchangeable lens in a direction perpendicular to the optical axis;
The image projection unit according to claim 1, wherein the lens moving unit is provided with the interchangeable lens mounting unit and the correction lens mounting unit.   The image projection unit according to claim 1, wherein the correction lens mounting portion is provided between an exit surface of the prism type element and an entrance surface of the interchangeable lens.   4. The opening of the correction lens mounting portion is provided with an opening that allows the correction lens to be manually attached or detached when the interchangeable lens is not mounted. 5. The image projection unit according to item.   The image correction unit according to claim 1, wherein the correction lens is a flat lens, a spherical lens, or an aspheric lens. The image projection unit according to any one of claims 1 to 5,
A projection-type image display apparatus comprising: an illumination optical system that divides illumination light into the plurality of color lights and irradiates the plurality of image display elements.

Images