ROTATABLE PROJECTION LENS AND PROJECTOR

A projection lens is separated into a first optical system that is disposed so as to be closer to an image forming panel and a second optical system that includes a mirror and is disposed so as to be closer to a screen which is a projection surface by the second mirror. The second optical system is set in a first position and a second position by inverting the second optical system around a second optical axis with respect to the first optical system by 180° by an inverting unit. An orientation of a projected image onto the screen is set in the first position and the second position by inverting the image displayed on the image forming panel according to the first position and the second position. It is possible to achieve projection for positioning a center of the screen above or under the optical axis by switching between the first position and the second position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection lens and a projector.

2. Description of the Related Art

In recent years, a projector in which an image forming panel such as a liquid crystal display device or a digital micromirror device (DMD) is mounted has come into wide use, and has been improved in performance.

JP2007-264554A describes a liquid crystal projector that irradiates a transmissive liquid crystal panel with light from a light source, enlarges an image displayed on the liquid crystal panel through a projection lens, and projects the enlarged image on a screen surface. The liquid crystal projector of JP2007-264554A includes a reflective member having a reflection surface which reflects video light including a projected video which is incident on a projection optical system which projects a video, and can change an inclined angle of the reflection surface with respect to the video light. Accordingly, it is possible to simply adjust a position of a projected surface on which the video is projected.

A liquid crystal projector of JP2009-217020A can project an optical image emitted from a projection lens in a horizontal direction and a vertical direction without changing a position of a main body of the liquid crystal projector by selectively disposing a minor inclined with respect to an optical axis by 45° in front of the projection lens.

SUMMARY OF THE INVENTION

In general, in a case where the main body has no lens shift function and a vertical direction of the projector main body is a normal orientation, the projector has a configuration in which a screen center is projected above an optical axis of the projection lens such that an image projected onto a screen is positioned above the projector. Accordingly, in a case where there is an attempt to project the screen center under the optical axis of the projection lens, it is necessary to dispose the projector main body upside down.

Even though a projection direction is switched by using the reflective member as in JP2007-264554A and JP2009-217020A, in a case where there is an attempt to project the screen center under the optical axis of the projection lens, it is necessary to similarly dispose the projector main body upside down.

However, it is necessary to prepare dedicated ceiling hanging equipment in order to dispose the projector main body upside down. An operation switch is present on an upper surface of the projector main body in many cases. Accordingly, in a case where the projector is used in a state in which the projector main body is disposed upside down, the operation switch faces downwards, and thus, it is difficult to perform the operation.

The present invention has been made in view of the circumstances, and an object of the present invention is to provide a projection lens and a projector capable of projecting a screen center toward a side opposite to a normal orientation with respect to an optical axis of the projection lens without disposing a projector main body upside down.

In order to achieve the object, a projection lens of the present invention projects an image on an image forming panel onto a projection surface, and the projection lens is used in a projector in which one of the image forming panel and the projection lens is disposed so as to be shifted in a direction perpendicular to an optical axis. The projection lens comprises a mirror that bends the optical axis, a first optical system, a second optical system, and an inverting unit. The first optical system is disposed closer to the image forming panel than the mirror. The second optical system includes the mirror and is disposed so as to be close to the projection surface. The inverting unit selectively holds the second optical system in a first position and a second position, which is inverted from the first position by 180°, around the optical axis with respect to the first optical system.

It is preferable that the mirror is provided in plural, and the mirror that separates the first optical system and the second optical system is the mirror closest to an emission side which is disposed so as to be closest to the projection surface on the optical axis.

It is preferable that the inverting unit comprises a sensor that detects the first position and the second position. It is preferable that the inverting unit has position indices that display the first position and the second position. It is preferable that the inverting unit switches the second optical system between the first position and the second position by rotationally moving the second optical system around the optical axis with respect to the first optical system. It is preferable that the inverting unit includes a click mechanism that fixes the second optical system to the first position and the second position.

It is preferable that the projection lens includes a light shielding unit. The light shielding unit shields light from the image forming panel in a non-detection state in which the second optical system is disposed in neither the first position nor the second position and the sensor is turned off.

A projector of the present invention comprises the projection lens, an image forming panel that displays an image, a light source that illuminates the image forming panel, a casing, and an image display inverting unit. The casing accommodates the image forming panel in a state in which one of the image forming panel and the projection lens is shifted in a direction perpendicular to the optical axis. The image display inverting unit inverts the image based on a signal of the sensor such that an orientation of a projected image of the projection surface is set in the first position and the second position in line with the switching of the second optical system between the first position and the second position.

It is preferable that the projector includes a light shielding unit. The light shielding unit shields light from the image forming panel in a non-detection state in which the second optical system is disposed in neither the first position nor the second position and the sensor is turned off. The light shielding unit may be provided within the projection lens, or may be provided between the projection lens and the image forming panel. It is preferable that the projection lens is attached to the casing so as to be attachable and detachable.

According to the present invention, it is possible to provide a projection lens and a projector capable of projecting a screen center toward a side opposite to a normal orientation with respect to an optical axis of the projection lens without disposing a projector main body upside down.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIG. 1, a projector2of the present embodiment comprises a projection lens10and a projector main body60.FIG. 1shows a case where the projector2is disposed on a horizontal plane such as a table.

As shown inFIG. 2, the projection lens10comprises a first optical system11, a second optical system12, a first mirror13, a second mirror14, a first holding member15, a second holding member16, and an inverting unit17. The first holding member15, the second holding member16, and the inverting unit17constitute a lens barrel18.

The first optical system11is constituted by a first lens21, a second lens22, a third lens23, a fourth lens24, and the first mirror13. The first lens21, the second lens22, and the fourth lens24are displayed as a single lens for simplicity of illustration, but are constituted by a plurality of lens groups in reality. The first lens21and the second lens22fauns an intermediate image on an imaging surface27by using illumination light from an image forming panel67.

The first mirror13is disposed between the second lens22and the third lens23. The first mirror13forms a second optical axis CL2crossing the first optical axis CL1at 90° by bending a first optical axis CL1of the first lens21and the second lens22by reflection.

The first holding member15includes a first main body30, a first lens frame31, a first attachment sleeve32, a second attachment sleeve33, and a third attachment sleeve34. The first holding member15integrally holds the first lens21to the fourth lens24and the first mirror13. The first main body30is constituted by an approximately rectangular parallelepiped square tube. One corner portion of a lower plate30aof the first main body30is obliquely cut, and thus, an inclined surface portion30bis formed. The first mirror13is fixed onto an inner surface of the inclined surface portion30b.

A first attachment hole30dof the first optical system11is formed in a front plate30con an entrance side facing the inclined surface portion30b.One end of the second attachment sleeve33is fixed to the first attachment hole30d.The second attachment hole30fis formed in an upper plate30eof the first main body30. A lower end portion of the third attachment sleeve34is fixed to the second attachment hole30f.The third attachment sleeve34holds third lens23and the fourth lens24according to the second optical axis CL2.

The second optical system12is constituted by the second mirror14, a fifth lens25, and a sixth lens26. The second mirror14is disposed between the fourth lens24and the fifth lens25. The second mirror14forms a third optical axis CL3crossing the second optical axis CL2by 90° by bending the second optical axis CL2by reflection. The fifth lens25and the sixth lens26are displayed as a single lens for simplicity in illustration, but are constituted by a plurality of lens groups in reality. The third lens23to the sixth lens26project the intermediate image formed on the imaging surface27by the first lens21and the second lens22onto, for example, a screen28which is a projection target.

The second holding member16includes a second main body40, a second lens frame42, and a third lens frame43. The second holding member16integrally holds the fifth lens25, the sixth lens26, and the second mirror14. The second main body40is constituted by an approximately rectangular parallelepiped square tube. One corner portion of an upper plate40aof the second main body40is obliquely cut, and thus, an inclined surface portion40bis formed. The second mirror14is fixed onto an inner surface of the inclined surface portion40b.

An attachment flange40cis formed on an end surface facing the inclined surface portion40bof the second main body40in a horizontal direction. The third lens frame43is fixed to the attachment flange40c.The second lens frame42is attached to one end of the third lens frame43so as to be movable in a direction of the third optical axis CL3. The fifth lens25is fixed to the second lens frame42, and the sixth lens26is fixed to the third lens frame43. The second lens frame42is moved along the third optical axis CL3by a lens movement mechanism (not shown), and adjusts a focus.

The lens configurations of the first lens21to the sixth lens26are described in detail in “projection optical system and projection display device” such as Japanese Patent Application No. 2015-035085 (corresponding to US 2016/246037 A1) and Japanese Patent Application No. 2015-045989, and the optical systems described in these documents can be used as the first optical system11and the second optical system12. According to the projection optical system and the projection display device, an optical system having high projection performance of which various aberrations are corrected in a wide angle is favorably obtained.

In the present embodiment, the first optical axis CL1of the first lens21and the second lens22is reflected by the first mirror13and is bent at 90°, and thus, the second optical axis CL2is formed. The second optical axis CL2of the third lens23and the fourth lens24is reflected by the second mirror14and is bent at 90°, and thus, the third optical axis CL3on an emission side is formed. The third optical axis CL3is parallel to the first optical axis CL1within a plane including the first optical axis CL1and the second optical axis CL2.

The inverting unit17is disposed between an upper end portion of the third attachment sleeve34and a lower plate40dof the second main body40. The inverting unit17includes a first flange45, a second flange46, a circumferential groove47, a guide pin48, a first sensor49, and a second sensor50. The first flange45is formed in a disc shape on an outer circumferential surface of the upper end portion of the third attachment sleeve34. The second flange46is formed in a disc shape on the lower plate40dof the second main body40.

As shown inFIG. 3, the circumferential groove47is a groove having a semicircular arc groove with the second optical axis CL2as a center, and is formed on a lower surface of the second flange46. As shown inFIG. 2, the guide pin48is formed in parallel with the second optical axis CL2so as to protrude from an upper surface of the first flange45. A front end of the guide pin48is inserted into the circumferential groove47in a state in which the first flange45and the second flange46are combined together. As shown inFIG. 3, the circumferential groove47is formed in an angle range of 180° with the second optical axis CL2as a center. Accordingly, the guide pin48guided to the circumferential groove47is movable within a length range of the circumferential groove47. Accordingly, the rotational movement of the second optical system12including the second main body40with respect to the first optical system11including the third attachment sleeve34is allowed at an angle of 180°, and thus, the second optical system can be inverted.

In a case where the guide pin48is positioned in one end portion of the circumferential groove47as shown inFIG. 3, the second optical system is positioned in a rear-surface projection position (corresponding to a first position) in which the sixth lens26of the second optical system12faces a rear surface as shown inFIG. 4. An image is projected so as to face the rear surface in the rear-surface projection position by the second optical system12. The image reflected in the screen28is projected onto a portion higher than the third optical axis CL3, and so-called upward projection is achieved.

Meanwhile, in a case where the second optical system12is inverted from the rear-surface projection position by 180° and the guide pin48is positioned at the other end portion of the circumferential groove47, the second optical system12is positioned in a front-surface projection position (corresponding to a second position) in which the sixth lens26faces a front surface, as shown inFIG. 5. The image is projected so as to face the front surface in the front-surface projection position by the second optical system12. The image reflected in the screen28is projected on a portion lower than the third optical axis CL3, and so-called downward projection is achieved.

As shown inFIGS. 2 and 3, the first sensor49and the second sensor50are attached to the first flange45in order to detect an orientation of the second optical system12. For example, a photo-interrupter is used as the first sensor49and the second sensor50. An L-shaped sensor plate57protruding in a radial direction is attached to an outer circumferential surface of the second flange46. The sensor plate57shields detection light rays of the first sensor49or the second sensor50, and thus, the first sensor49and the second sensor50are turned on. In a case where the first sensor49is turned on, it is detected that the second optical system12is set in the rear-surface projection position. In a case where the second sensor50is turned on, it is detected that the second optical system12is set in the front-surface projection position. Meanwhile, in a case where the second optical system12is positioned in neither the rear-surface projection position nor the front-surface projection position, the first sensor49and the second sensor50are turned off. Hereinafter, this state is referred to as a non-detection state.

Signals of the first sensor49and the second sensor50are sent to a controller69of the projector main body60through a mount unit61to be described below. Since the sensors49and50are attached to the first flange45on a fixed side at the time of inverting the second optical system, wiring for the sensors49and50is easier than wiring in a case where the sensors49and50are attached to the second flange46.

As shown inFIG. 6, a click mechanism51is provided on a combined surface of the first flange45and the second flange46. The click mechanism51includes a locking hole52, a locking ball53, a coil spring54, and a spring suppression screw55, and positions the second optical system12in the rear-surface projection position and the front-surface projection position. The locking hole52is a spherical recess, and is formed in positions of the combined surface of the first flange45which correspond to the rear-surface projection position and the front-surface projection position. The spring suppression screw55is screwed to a locking ball accommodation hole56, and holds the locking ball53and the coil spring54in the locking ball accommodation hole56. The locking ball53is biased so as to come in contact with the combined surface of the first flange45by the coil spring54.

The first holding member15and the second holding member16are individually assembled. As shown inFIG. 2, the first holding member15and the second holding member16are joined through the inverting unit17in a state in which the second optical axis CL2on the emission side of the first optical system11and the second optical axis CL2on an incidence side of the second optical system12are together, and thus, the lens barrel18is assembled. In the lens barrel18assembled in this manner, a U-shaped optical path is formed by the second optical axis CL2, the first optical axis CL1on the incidence side of the first optical system11, which has an angle of 90° with respect to the second optical axis CL2, and the third optical axis CL3on the emission side of the second optical system12.

As shown inFIG. 1, the projection lens10is attached to the projector main body60through the mount unit61so as to be attachable and detachable. The projector main body60includes an approximately rectangular parallelepiped casing65. A light source66, the image forming panel67, a light shielding unit68, and the controller69are accommodated within the casing65.

For example, a transmissive liquid crystal panel is used as the image forming panel67. The light source66is disposed on a rear surface of the image forming panel67, that is, a side opposite to the projection lens10with the image forming panel67as a reference. Light-emitting diodes (LEDs) that simultaneously emit three colors of red (R), green (G), and blue (B) are used as the light source66, and illuminates the image forming panel67. A xenon lamp, a halogen lamp, or an extra-high pressure mercury lamp which emits white light may be used instead of the LEDs. The projection lens10projects the illumination light from the image forming panel67illuminated by the light source66onto a projection surface, for example, the screen28.

For example, the light shielding unit68is disposed between the image forming panel67and the first lens21. The light shielding unit68is used for selectively inserting a mechanical shutter which opens and closes a shutter or an ND filter into an optical path. A state of projection light is switched between a light shielding state in which the projection light from the image forming panel67and a transmission state in which the projection light is transmitted by the light shielding unit68. As shown in a dashed double-dotted line inFIG. 2, the light shielding unit68may be provided in the projection lens10instead of being provided in the projector main body60.

The controller69turns on the light source66, and displays an image of three RGB colors on an image forming surface67awhich is a surface of the image forming panel67on a side opposite to a surface facing the light source66. The controller69includes an image display inverting unit69a.The image display inverting unit69acontrols the inverting of the image based on stoppage position signals for the second optical system12from the sensors49and50. In a case where the first sensor49is turned on and the second optical system12is in the rear-surface projection position and enters a rear-surface upward projection state, the controller displays a normal image (an erect image) on the image forming panel67. In a case where the second optical system12is in a front-surface projection position and enters a front-surface downward projection state, the controller displays an inverted image acquired by inverting the image upside down on the image forming panel67.

In the non-detection state in which the second optical system12is disposed in neither the rear-surface projection position nor the front-surface projection position and the first sensor49and the second sensor50are turned off, the controller69shields the projection light from the image forming panel67by operating the light shielding unit68. Meanwhile, in a state other than the non-detection state, the controller69sets the projection light from the image forming panel67in the transmission state by operating the light shielding unit68.

FIG. 7is a flowchart showing a procedure for image display inverting control and the control of the light shielding unit68using the controller69based on the signals of the first sensor49and the second sensor50. In a case where the first sensor49is turned on (Y in step ST100, in a case where the second optical system12is disposed in the rear-surface projection position which is the first position), the controller69sets the projection light from the image forming panel67in the transmission state by operating the light shielding unit68(step ST110), and displays the erect image by controlling the image display inverting unit69a(step ST120). Accordingly, as shown inFIG. 4, the image is projected onto the portion of the screen28higher than the third optical axis CL3, and the so-called upward projection is achieved.

Meanwhile, in a case where the second sensor50is turned on (Y in step ST130, in a case where the second optical system12is disposed in the front-surface projection position which is the second position), the controller69sets the projection light from the image forming panel67in the transmission state by operating the light shielding unit68similarly to step ST110(step ST140), and displays the inverted image by controlling the image display inverting unit69a(step ST150). Accordingly, as shown inFIG. 5, the image is projected onto the portion of the screen28lower than the third optical axis CL3, and the so-called downward projection is achieved. As stated above, an orientation of the projected image onto the screen28is switched so as to be set in the rear-surface projection position or the front-surface projection position based on the signals of the first sensor49and the second sensor50by the image display inverting unit69ain line with the switching of the second optical system12between the rear-surface projection position and the front-surface projection position.

In a case where the first sensor49and the second sensor50are turned off, that is, in the non-detection state (N in both step ST100and step ST130), since the second optical system12is rotationally moving, the controller69shields the projection light from the image forming panel67by operating the light shielding unit68(step ST160). In this state, the projection light from the image forming panel67is shielded by the light shielding unit68, the image is not projected from the second optical system12. Hereinafter, while a main switch is turned on (N in step ST170), the processes are repeated. In a case where the main switch is turned off (Y in step ST170), the control is ended.

The controller69also performs the following processes. For example, in a case where the projection lens10has an electric zoom control function and an operation signal for a zoom dial71(seeFIG. 1) is received, a size of the image projected onto the screen28is adjusted. In a case where an operation signal for a focus dial73(seeFIG. 1) is received, the controller69adjusts a focus of the image projected onto the screen28by operating a focus adjustment mechanism (not shown) of the projection lens10.

As shown inFIG. 2, the image forming panel67is disposed so as to be shifted downwards from the first optical axis CL1. For example, the image is displayed under the first optical axis CL1. In contrast, the image projected through the first optical system11and the second optical system12is displayed on the screen28so as to be shifted above the third optical axis CL3. Accordingly, as shown inFIG. 4, the image is projected onto the screen28disposed on a rear side so as to be higher than the third optical axis CL3in the rear-surface projection position.

In a case where there is an attempt to project the image under the third optical axis CL3, the second optical system12is rotated (inverted) around the second optical axis CL2by 180° by using the second main body40. Accordingly, as shown inFIG. 5, the sixth lens26faces a front side. In this state, the downward projection in which the image projected on the screen28is positioned under the third optical axis CL3is achieved due to the reflection using the second mirror14.

As stated above, it is possible to simply switch between the upward projection and the downward projection by a simple operation for rotating the second optical system12around the second optical axis CL2by 180° without inverting the projector main body60upside down. In this switching, the image displayed on the image forming panel67is inverted upside down by the image display inverting unit69a.Accordingly, the orientation of the image after the switching may not be inverted upside down.

Since the projection light is shielded by the light shielding unit68in the non-detection state which the switching is being performed, the projection light is not projected from the projection lens10being moved rotationally, and it is possible to eliminate discomfort during the switching. Since the second optical system12is positioned in the rear-surface projection position and the front-surface projection position by the click mechanism51, it is possible to reliably invert the second optical system12.

Various inverting guide mechanisms can be used as the inverting unit17as long as the inverting guide mechanism can rotate the third attachment sleeve34and the second main body40around the second optical axis CL2by 180°. For example, the second optical system12is inverted by forming a circumferential groove in an outer circumferential surface of the third attachment sleeve34, forming a guide pin inserted into the circumferential groove in an inner circumferential surface of an attachment hole of the second main body40to which the third attachment sleeve34is attached, and regulating the movement of the guide pin by using the circumferential groove. Although the second optical system12is manually inverted, the second optical system may be automatically inverted by providing a rotational movement gear integrally with the second flange46and rotating this rotational movement gear by a motor. In this case, a switch for switching between the positions of the second optical system12by driving the motor is provided at the casing65.

Two mirrors13and14are used in the first embodiment. In a second embodiment shown inFIGS. 8 to 11, the first mirror13is removed, only the second mirror14is used, and the optical axis has an L shape. In this second embodiment, a cylindrical first main body75is provided instead of the first main body30of the first embodiment which is the approximately rectangular parallelepiped square tube. The first main body75is accommodated in the projector main body60. The second mirror14forms the second optical axis CL2by bending the first optical CL1(not shown) of the first lens21and the second lens22. The second embodiment has the same configuration as the first embodiment except that the first mirror13of the first embodiment is removed and the first main body75has the cylindrical shape. In the following embodiment, the same components as those of the first embodiment will be assigned the same references, and the redundant description thereof will be omitted.

In the second embodiment, the second optical system12can be rotated around the first optical system11by 180° by the inverting unit17as in the first embodiment by using one mirror14. Accordingly, the upward projection for displaying the image above the second optical axis CL2as shown inFIG. 10and the downward projection for displaying the image under the second optical axis CL2as shown inFIG. 11can be achieved. In the second embodiment, the position of the second optical system12shown inFIG. 10corresponds to the first position, and the position of the second optical system12shown inFIG. 11corresponds to the second position. According to the second embodiment, it is possible to project a screen center toward a side opposite to a normal orientation with respect to the optical axis CL3without disposing the projector main body60upside down.

Although the inverting unit17for rotating the second optical system12is used in a state in which the second optical system12is connected to the first optical system11in the first and second embodiments, an inverting unit80using a fitting method is used in a third embodiment shown inFIGS. 12 and 13. The inverting unit80includes two key grooves82and one key protrusion84. The key grooves82are formed in the first flange81of the first optical system11in parallel to the second optical axis CL2in positions spaced apart from each other by 180° in a circumferential direction. The key protrusion84is a columnar protrusion extending in parallel with the second optical axis CL2. The key protrusion84protrudes downwards from a lower surface of the second flange83formed on the second main body40, and is disposed on an outer circumference of the third attachment sleeve34.

In a case where the second optical system12is assembled to the first optical system11, the key protrusion84is inserted into one key groove82or the other key groove82, and thus, it is possible to switch between the fitting positions of the second optical system12with respect to the first optical system11as shown inFIGS. 12 and 13. Key sensors85are attached to the third attachment sleeve34in positions corresponding to the key grooves82. The key sensor85is, for example, a limit switch, and detects the key protrusion84. The key sensor85can detect whether the second optical system12is in the first position or the second position. In the third embodiment, the position of the second optical system12shown inFIG. 12corresponds to the first position, and the position of the second optical system12shown inFIG. 13corresponds to the second position. According to the third embodiment, it is possible to project the screen center toward the side opposite to the normal orientation with respect to the optical axis CL3without disposing the projector main body60upside down.

Although one mirror14or the two mirrors13and14are used in the embodiments, the number of mirrors may be three or more. In this case, the projection lens is separated into the first optical system11and the second optical system12by the mirror closest to the emission side which is disposed so as to be closest to the screen28which is the projection surface on the optical axis. However, the mirror closest to the emission side in the first embodiment is the second mirror14.

In the first embodiment, the second optical system12is selectively stopped in the rear-surface projection position which is the first position and the front-surface projection position which is the second position by using the click mechanism51in the first embodiment. Instead of or in addition to the aforementioned positioning method of the second optical system, the second optical system12may be positioned in the first position and the second position by using a reference index90and position indices91as shown inFIG. 14. The reference index90is formed at an outer circumferential portion on an upper surface of a second flange89formed on the second main body40. The second flange89is formed so as to have an outer diameter smaller than the second flange46of the first embodiment. Accordingly, an outer circumferential portion of the first flange45is exposed from an outer circumference of the second flange89in plan view. The position index91is formed on the upper surface of the exposed outer circumferential portion of the first flange45. The position index91is connected to the reference index90in a straight line in a case where the second optical system is in the first position and the second position. Accordingly, the position index91matches the reference index90by rotationally moving the second optical system12, and thus, it is possible to selectively position the second optical system12in the first position and the second position with respect to the first optical system11.

Although the transmissive liquid crystal panel is used as the image forming panel67in the embodiments, a reflective liquid crystal panel may be used. In this case, the light source66is disposed on the front side of the image forming panel67, and the irradiation light rays of three RGB colors are simultaneously irradiated. In a case where the DMD is used as the image forming panel67, the light source66is disposed on the front side of the image forming panel67, and LEDs of three RGB colors are emitted in time division in synchronization with a forming timing of a three-color image of the DMD.

Although it has been described in a state in which the projector2is disposed on the table in the embodiments, the present invention is also applicable to a case where the projector2hung from a ceiling is used. Although it has been described that the image is projected onto the screen28, the projection surface is not limited to the screen28. A projector that projects the image onto various projection surfaces can be used.

It has been described in the embodiments that the terms of perpendicular and parallel are used for expressing the positional relationship between the plurality of optical axes or the specific numerical angle such as 90° is used. However, these terms and numerical angle include a range allowable within an error corresponding to accuracy required in the optical system.

Although the projector2including the exchangeable projection lens10through the mount unit61is described in the first embodiment, the projection lens10is also applicable to a projector fixed to the projector main body60. For example, in a case where the exchangeable projection lens10is used, some lenses of the first optical system11, for example, the first lens21and the second lens22may be provided in the projector main body, and the number of lenses on the projection lens10's side may be reduced.

Although the image forming panel67is shifted under the first optical axis CL1in the first embodiment, the image forming panel may be shifted above the first optical axis. The target shifted in a direction perpendicular to the first optical axis CL1may be the projection lens10instead of the image forming panel67, or both the image forming panel67and the projection lens10may be shifted and arranged.

Explanation of References

11: first optical system

12: second optical system

13: first mirror

14: second mirror

15: first holding member

16: second holding member

21: first lens

22: second lens

23: third lens

24: fourth lens

25: fifth lens

27: imaging surface

30: first main body

30a: lower plate

30b: inclined surface portion

30c: front plate

30d: first attachment hole

30e: upper plate

30f: second attachment hole

31: first lens frame

32: first attachment sleeve

33: second attachment sleeve

34: third attachment sleeve

40: second main body

40a: upper plate

40b: inclined surface portion

42: second lens frame

43: third lens frame

45: first flange

48: guide pin

49: first sensor

50: second sensor

51: click mechanism

54: coil spring

55: spring suppression screw

56: locking ball accommodation hole

57: sensor plate

60: projector main body

61: mount unit

66: light source

67: image forming panel

67a: image forming surface

68: light shielding unit

69a: image display inverting unit

71: zoom dial

73: focus dial

75: first main body

81: first flange

82: key groove

85: key sensor

90: reference index

91: position index

CL1: first optical axis

CL2: second optical axis

CL3: third optical axis