Projection direction change device and image projection system

A projection direction change device includes a mirror that reflects light emitted from a projection lens unit of a projector, a mirror support part that rotatably supports the mirror around a first axis and a second axis, a first drive part that rotary drives the mirror around the first axis, and a second drive part that rotary drives the mirror around the second axis. An intersecting point of the first and second axes is positioned closer to the projection lens unit than a geometric barycenter of the mirror is.

BACKGROUND

1. Technical Field

The present disclosure relates to a projection direction change device that changes the projection direction of an image projected from a projector.

2. Description of the Related Art

A projection direction change device, also called a moving mirror, changes the projection direction of an image projected from a projector and allows the image to be projected in widespread directions. If a projector is installed under some constraints or is heavy, it is effective to change the projection direction of an image using a projection direction change device.

In patent literature (PTL) 1, a mirror is disposed between the lens of the projection optical system of a projector and a screen, and the projection direction of the image is changed by the mirror to further correct the distortion of the image.

Attempting to project a projection image in widespread directions by increasing the inclination angle of the mirror, however, requires a large mirror, which may undesirably be in contact with the projection lens unit of the projector.

SUMMARY

An object of the present disclosure is to provide a projection direction change device and an image projection system that largely change the range of projection directions with a limited increase of the sizes of the device and the system.

A projection direction change device of the present disclosure includes

a mirror that reflects light emitted from a projection lens unit of a projector,

a mirror support part that rotatably supports the mirror around a first axis and a second axis,

a first drive part that rotary drives the mirror around the first axis, and

a second drive part that rotary drives the mirror around the second axis,

where an intersecting point of the first and second axes is positioned closer to the projection lens unit than a geometric barycenter of the mirror is.

An image projection system of the present disclosure includes

the above-described projection direction change device having a mirror controller that indicates a drive amount of the mirror to the first and second drive parts,

the projector that projects an image,

an image output device that outputs an image to the projector, and

a controller that sends a command signal about the attitude of the mirror to the mirror controller and outputs an image output signal synchronized with the command signal to the image output device.

A projection direction change device and an image projection system largely change the range of projection directions while limiting an increase of the sizes of the device and system.

DETAILED DESCRIPTION

Hereinafter, a detailed description is made of some embodiments with reference to the related drawings as appropriate. However, a detailed description more than necessary may be omitted, such as a description of a well-known item and a duplicate description for a substantially identical component, to avoid an unnecessarily redundant description and to allow those skilled in the art to easily understand the following description.

Note that the accompanying drawings and the following description are provided for those skilled in the art to well understand the disclosure, and it is not intended that the drawings and the description limit the subjects described in the claims.

A rough description is made of the difference between projection direction change device201as a comparative example and projection direction change device1of the present disclosure in reference toFIGS.1and2.FIG.1is an outline sectional view of projection direction change device201as a comparative example.FIG.2is an outline sectional view of projection direction change device1of the present disclosure.

As shown inFIG.1, mirror203as a comparative example is capable of pan rotation with the Y-axis direction being rotation axis Ry (the first axis) and tilt rotation with the X-axis direction being rotation axis Rx (the second axis). Mirror203is supported so that geometric barycenter Pg1of mirror203(uniform in weight across the mirror surface) is positioned equal to intersecting point Pr1of the two rotation axes of pan rotation and tilt rotation of mirror203.

Distance L1from the end of mirror203opposite to projection lens unit205to intersecting point Pr1of the two rotation axes is roughly the same as distance L2from intersecting point Pr1to the end of mirror203closer to projection lens unit205. In this case, projection lens unit205must be spaced from intersecting point Pr1of the two rotation axes to the degree that the end of mirror203closer to projection lens unit205does not interfere with projection lens unit205while tilt rotation around rotation axis Rx is driven. Intersecting point Pr1of the two rotation axes is disposed on optical axis La of light emitted from projection lens unit205. This prolongs the distance from the region of mirror203opposite to projection lens unit205to projection lens unit205, and an image projected from projection lens unit205is magnified and is projected into the region of mirror203opposite to projection lens unit205. Accordingly, the size of mirror203needs to be increased in order that the whole light projected from projection lens unit205is projected onto mirror203.

In projection direction change device1of the present disclosure, on the other hand, intersecting point Pr2of the two rotation axes is positioned closer to projection lens unit113than geometric barycenter Pg2of mirror26is. Distance L4from intersecting point Pr2to the end of mirror26closer to projection lens unit113is shorter than distance L3from the end of mirror26opposite to projection lens unit113to intersecting point Pr2of the two rotation axes. This shortens the distance from the region of mirror26opposite to projection lens unit113to projection lens unit113even if projection lens unit113is spaced from intersecting point Pr2of the two rotation axes to the degree that the end of mirror26closer to projection lens unit113does not interfere with projection lens unit113. This suppresses an increase of the size of an image projected into the region of mirror26opposite to projection lens unit113. Accordingly, mirror26can be downsized, and so can projection direction change device1and image projection system100(refer toFIG.8). Note that rotation axis Ry can be parallel-translated in direction Z, where the intersecting point of a straight line vertically projected onto the surface of mirror26standing up from rotation axis Ry and rotation axis Rx is to be intersecting point Pr2.

First Exemplary Embodiment

Hereinafter, a description is made of the first exemplary embodiment as an example of above-described projection direction change device1in reference toFIGS.3through7.

FIG.3is a perspective view of projection direction change device1according to the first exemplary embodiment of the present disclosure, viewed from the front.FIG.4is a front view of projection direction change device1, viewed from the front.FIG.5is a perspective view of mirror unit3, viewed from the back. For convenience of the following description, each figure is assumed to be based on the XYZ rectangular coordinate system shown in the figure. Note that the reflection direction of mirror26is front in a state where mirror26is not rotating.

Projection direction change device1changes the projection direction of light projected from projection lens unit113of projector111. Projection direction change device1includes mirror unit3, head case part5composed of first case5aand second case5b, mirror controller7, support9, attaching part11, and connector13.

Mirror unit3includes mirror part21that reflects light projected from projection lens unit113, mirror support part23that rotatably supports mirror part21, and mirror driver25that rotary drives mirror part21. Note that, in projector111, projection lens unit113that projects an image displayed by image display device115(refer toFIG.9) is composed of multiple lens groups.

Mirror part21includes mirror26that reflects light projected from projection lens unit113and mirror frame27fitted onto the outer edge of mirror26. Mirror26has a hexagonal shape for example, where it may have a polygonal shape (at least a triangular shape) and its outer edge may be curved. Mirror26has a wider region opposite to projection lens unit113than the region closer to projection lens unit113. For example, mirror26has a shape formed by two trapezoids combined to each other with one side common, where the side closer to projection lens unit113of mirror26is shorter than the side opposite to projection lens unit113. Mirror26, for example, has a shape in which the region expands outward from the side closer to projection lens unit113and then the region contracts inward. Mirror26may have any one of the shapes: planar, concave, and convex.

Mirror frame27is rotatably supported by mirror supporting part23around the X and Y axes. Mirror frame27has rib27aand multiple through holes27bformed so that the barycenter of mirror part21(formed by unifying mirror26and mirror frame27) is positioned on intersecting point Pr2of the two axes: the support shaft (coincident with rotation axis Rx) of mirror frame27at mirror support part23and rotation axis Ry of mirror support part23. Also, mirror frame27has first gear27c(like a semicircular plate) formed on the back surface. The weight of mirror part21is adjusted by rib27a, through holes27b, and first gear27c. Through hole27bof a larger region is formed opposite to projection lens unit113than closer to projection lens unit113of mirror frame27, and thus the barycenter of mirror frame27is positioned closer to projection lens unit113than geometric barycenter Pg2of mirror26is.

Mirror frame27has two pins27dextending outward from the outer edge. Each of two pins27dis rotatably inserted into hole23aprovided at the tip of mirror support part23. The two pins function as rotation axis Rx of tilt rotation.

Mirror driver25includes first drive part31that rotary drives mirror part21around the Y axis and second drive part41that rotary drives mirror part21around the X axis.

First drive part31changes the inclination angle of mirror part21around the Y axis. First drive part31includes first motor33, driven pulley35that is driven by the rotation of first motor33, and belt37that transmits the rotation output of first motor33to driven pulley35. Rotation axis39of driven pulley35, connected with mirror support part23, pan-rotates mirror support part23in response to the rotation amount of first motor33. Rotation axis39of driven pulley35is rotation axis Ry (the first axis). First motor33, driven pulley35, and belt37are accommodated in head case part5. Mirror26supported by mirror support part23is rotatable (e.g., 260°) around rotation axis Ry by first motor33. First motor33is electrically connected with mirror controller7, which controls the rotation amount of first motor33.

Second drive part41changes the inclination angle of mirror part21around the X axis. Second drive part41includes second motor43. Second motor43has output gear43a, which engages with first gear27c. Second motor43is supported by mirror support part23. Rotation of output gear43aof second motor43rotates first gear27ctogether with mirror frame27, and mirror part21tilt-rotates. Mirror26supported by mirror support part23is rotatable (e.g., 0° to 90°) around rotation axis Rx (the second axis) by second motor43. Mirror26, thus rotatable from a state orthogonal to optical axis La to a state parallel with optical axis La, reflects projection light in a range between 0° and 90°. Note that rotation axis Ry and rotation axis Rx are orthogonalized to each other for example. Second motor43is electrically connected with mirror controller7, and the rotation amount of the motor is controlled by mirror controller7.

Mirror controller7, connected with connector13, is capable of receiving a command signal from the outside through connector13. Mirror controller7sends a drive signal to first motor33and second motor43.

Support9connects head case part5in which mirror controller7is accommodated with attaching part11. The position of direction Y of support9is adjustable by means of adjustment mechanism10, and thus the distance between projection lens unit113and mirror part21can be adjusted in response to the length of projection lens unit113. This allows the length of support9to be adjusted in response to the length of projection lens unit113so that the distance between projection lens unit113and mirror26is minimized to the degree that mirror26in a movable state does not interfere with projection lens unit113. This allows mirror part21to be disposed at a position where the spread of projection light from projection lens unit113is suppressed, which suppresses upsizing of mirror part21.

Support9and attaching part11are provided with length adjustment mechanism10that adjusts the connection position. Support9has multiple through holes9avertically formed in the bottom of support9. Attaching part11has multiple bolt holes11avertically formed in the surface in contact with support9. The bottom of support9is slidably connected to attaching part11. Length adjustment mechanism10is composed of through holes9a, bolt holes11a, and bolts12. Support9is slided so that support9is at a desired height, bolts12are inserted in a state where through holes9aof support9are aligned with bolt holes11aof attaching part11, and they are fastened. Note that length adjustment mechanism10may be of another configuration, such as a motor and a rack pinion set.

Attaching part11is an attachment for fastening projection direction change device1to projector111. Attaching part11is U-shaped for example. The bottom surface of attaching part11is attached on the plane where projection lens unit113of projector111is disposed so that attaching part11encloses lens barrel113aof projection lens unit113. Note that attaching part11may be attached to lens barrel113aof projection lens unit113.

Connector13, disposed on support9, is connected with mirror controller7. The socket of a communication cable connected with an outside control device is disposed so that the cable can be inserted into connector13in whatever attitude projector111is placed. Connector13is provided opposite to mirror26of support9for example. Connector13may be disposed on head case part5.

Next, a description is made of the configuration of image projection system100including projection direction change device1in reference toFIG.8.FIG.8is a block diagram illustrating the configuration of image projection system100.

Image projection system100includes projector system110, controller101, and image output device103, for example.

Controller101controls the image output to projector111. Also, controller101generates a control command containing drive information, such as a target angle (pan and tilt angles) of the rotation of mirror part21corresponding to an image to be output, rotary drive speed, and drive acceleration, and then sends the control command to mirror controller7through connector13of projection direction change device1.

Controller101can be implemented from semiconductor devices for example. Controller101can be composed of a microprocessor, CPU, MPU, GPU, DSP, FPGA, and ASIC, for example. The functions of controller101may be performed by hardware devices only, or a combination of hardware devices and software programs. Controller101has a storage part such as a hard disk drive (HDD), SSD, and memory. Controller101reads data and programs stored in the storage part and performs various types of operations to implement given functions.

Communications from controller101to mirror controller7may be serial communications (e.g., RS232C) or IP communications through a LAN. In synchronization with transmission timing of a control command from controller101to mirror controller7, a control command containing drive information of mirror part21is output from controller101also to image output device103. In synchronization with this control command, a projection image is output from image output device103to projector111. Note that controller101and image output device103may be an identical device composed of one personal computer (PC) or an edge terminal, for example.

Mirror controller7includes motor controller51, memory53, first motor driver55, and second motor driver57. Mirror controller7can be implemented from semiconductor devices for example. Mirror controller7can be composed of a microprocessor, CPU, MPU, GPU, DSP, FPGA, and ASIC, for example. The functions of mirror controller7may be performed by hardware devices only, or a combination of hardware devices and software programs. Mirror controller7reads data and programs stored in memory53and performs various types of operations to implement given functions.

Motor controller51of mirror controller7transforms a control command received from controller101to a motor driver control signal, and sends a corresponding motor driver control signal to first motor driver55and second motor driver57. Mirror controller7enters the initial examination mode in which the states of first motor33, second motor43, and the gear are monitored when projection direction change device1is started up (e.g., power up). Motor controller51sends multiple patterns of test signals to first motor driver55and second motor driver57, and refers to the test results when transforming a control command to a motor driver control signal.

Note that instead of sending a control command as a command signal from controller101to motor controller51, the following way may be used. That is, a mirror operation sequence composed of a sequence of a pan angle and tilt angle is stored in memory53of mirror controller7in advance, and a timing signal received from controller101triggers motor controller51to read the mirror operation sequence.

Image output device103outputs an image to projector111according to drive information from controller101and an image output signal specifying the type of an image to be displayed. Image output device103includes image processor103aand memory103b. Memory103bstores multiple types of image data as a base to be output to projector111. Image processor103apredicts the distortion of an image at mirror part21referring to distortion information of a projection image and performs image correction about the direction and amount of distortion in image data as a base specified by an image output signal. Distortion information contains a control command sent from controller101to mirror controller7and information about a projection surface.

As described above, projection direction change device1according to the first exemplary embodiment includes mirror26that reflects light emitted from projection lens unit113of projector111, mirror support part23that rotatably supports mirror26around the two axes of tilt rotation and pan rotation, first drive part31that rotary drives mirror26around the rotation axis of tilt rotation, and second drive part41that rotary drives mirror26around the rotation axis of pan rotation. Intersecting point Pr2of rotation axis Rx of pan rotation and rotation axis Ry of tilt rotation is positioned closer to projection lens unit113than geometric barycenter Pg2of mirror26is. With this simple configuration, intersecting point Pr2of the two rotation axes is positioned closer to projection lens unit113than geometric barycenter Pg2of mirror26is. The distance from intersecting point Pr2to the end of mirror26closer to projection lens unit113is shorter than the distance from the end of mirror26opposite to projection lens unit113to intersecting point Pr2of the two rotation axes. This shortens than ever the distance from the region of mirror26opposite to projection lens unit113to projection lens unit113even if projection lens unit113is spaced from intersecting point Pr2of the two rotation axes to the degree that the end of mirror26closer to projection lens unit113does not interfere with projection lens unit113. This suppresses an increase of the size of an image projected into the region of mirror26opposite to projection lens unit113of mirror26. This increases the rotation angle of mirror26to increase the range of changing projection directions of light from projection lens unit113, and mirror26can be downsized, as well as projection direction change device1and image projection system100.

Also, the weight balance of mirror frame27has been adjusted so that the barycenter of mirror part21(refer toFIG.3) composed of mirror26and mirror frame27is positioned closer to intersecting point Pr2of two rotation axes than geometric barycenter Pg2of mirror26is. This reduces the drive load while mirror part21is rotary driven. When intersecting point Pr2of the barycenter of mirror part21is positioned at intersecting point Pr2of two rotation axes, the drive load can be minimized while mirror part21is rotary driven.

Second Exemplary Embodiment

Hereinafter, a description is made of the second exemplary embodiment in reference toFIG.9.

FIG.9is a block diagram illustrating the configuration of image projection system100A according to the second exemplary embodiment of the present disclosure.

In image projection system100A of the second embodiment, a makeup in which projection lens unit113of projector111is driven in conjunction with the action of an image has been added to image projection system100of the first embodiment. The makeups other than that described above and those described hereinafter are common between image projection system100A of the second embodiment and image projection system100of the first embodiment.

Image projection system100A includes projector system110A, controller101, and image output device103. Projector system110A includes projector111A and projection direction change device1.

Projector111A includes image display device115and lens driver117. Image display device115displays an image sent from image processor103a. Lens driver117moves some or all of the lenses in projection lens unit113that projects an image displayed by image display device115along the optical axis. Lens driver117also shifts the optical axis. Lens driver117is a mechanism for zoom adjustment, focus adjustment, and shift adjustment of projection lens unit113for example. In the second embodiment, lens driver117adjusts the projection functions of the projector, including at least one of the zoom function, focus function, and shift function of projection lens unit113, in conjunction with the rotation of mirror part21.

Controller101sends a control signal for lens drive to lens driver117of projector111A in synchronization with a control command to be sent to projection direction change device1. A control signal for lens drive contains information about a zoom amount, a focus position, and a shift position of projection lens unit113, for example. A control signal for lens drive is calculated by controller101according to drive information about rotary driving of mirror part21contained in a control command. Lens driver117drives some or all of the lenses in projection lens unit113based on a control signal for lens drive.

Controller101generates a control signal for lens drive with the focus position changed so that an image to be projected is in focus in a case where the projection distance changes, for example, when the projection surface (e.g., a wall) moves to another surface due to rotation of mirror part21. Using this signal, lens driver117adjusts the focus amount of projection lens unit113, which prevents an image to be projected from being out of focus even if the projection surface has changed.

Controller101generates a control signal for lens drive with the zoom amount adjusted in conjunction with mirror drive so that the size of a projection image does not change while mirror part21is rotating. Using this signal, lens driver117adjusts the zoom amount of projection lens unit113, which prevents the size of a projection image from changing even when the projection distance has changed.

Controller101generates a control signal for lens drive for shifting the optical axis of projection lens unit113(multiple lenses included) so that image vignetting is minimized within the rotation range of mirror part21if the range is known in advance, or so that the loss of resolution due to image correction is minimized. With this signal, lens driver117shifts the optical axis of projection lens unit113, which suppresses an increase of image vignetting.

Lens driver117thus moves the optical axes of some or all of the lenses in projection lens unit113along or parallel with the projection direction in synchronization with a control command sent from controller101to mirror controller7for drive-controlling mirror26, based on a control signal for lens drive that is a command signal from controller101. In other words, lens driver117adjusts the projection function of projector111A in collaboration with drive-control of mirror26of projection direction change device1based on a command signal from controller101. This adjustment prevents the deterioration of an image projected onto a projection surface due to a change of the projection direction by mirror26.

Third Exemplary Embodiment

Hereinafter, a description is made of the third exemplary embodiment in reference toFIG.10.

FIG.10is a schematic diagram illustrating the configuration of image projection system100B according to the third embodiment of the present disclosure.

In image projection system100B of the third embodiment, attitude sensor59that detects a state of the attitude of mirror part21has been added to projection direction change device1of image projection system100of the first embodiment. The makeups other than that described above and those described hereinafter are common between image projection system100B of the third embodiment and image projection system100of the first embodiment.

Attitude sensor59, attached to projection direction change device1B, measures the attitude angle of mirror26. Attitude sensor59is a motion sensor such as a gyro sensor. Measurement of a state of the attitude of mirror26by attitude sensor59is performed when projection direction change device1B is started up, always, or on a user's command.

Attitude data, detected by attitude sensor59, representing a state of the attitude of mirror part21is converted to a reference position at that time and a step amount of drive (e.g., pan rotation, tilt rotation) by motor controller51, and the resulting data is used as correction data for a motor driver control signal created based on a control command. This data further increases the rotation accuracy of mirror26.

Other Exemplary Embodiments

Hereinbefore, the description is made of the embodiments for exemplification of the technologies in the disclosure. However, these technologies are not limited to the embodiments, but are also applicable to embodiments that have undergone change, substitution, addition, and/or omission.

In the above-described embodiment, attaching part11of projection direction change device1is attached to the surface of projector111from which lens barrel113aof projection lens unit113protrudes, but the disclosure is not limited to this embodiment. For projector111vertically placed, like projector system110A shown in modified example 1 ofFIG.11, arm11bconnected with attaching part11may be attached to side surface111aof projector111, in addition to the makeup in which attaching part11is attached to one surface of projector111from which lens barrel113aprotrudes. Arm11bmay be attached directly to the side surface of the main body of projector111, or to frame111bthat supports the main body of projector111, as shown inFIG.11. In this way, in addition to one surface of the main body of projector111, projection direction change device1attached to another surface of the main body of projector111or to the main body allows projection direction change device1to be supported by at least two surfaces of the main body of projector111. Accordingly, projection direction change device1can be placed more stably. Besides, arm11battached to a frame supporting the main body of projector111, instead of another surface of the main body of projector111, provides the similar advantage.

Depending on the attitude of projector111, projection direction change device1may be unstable when it is simply attached to lens barrel113aby gravity. In this case, a support mechanism may be provided that holds or supports projection direction change device1of a surface of frame111bor the main body of projector111vertical to the gravitational direction. For ceiling-hung projector111horizontally placed, like projector system110B shown in modified example 2 ofFIG.12for example, projection direction change device1may be fastened to a surface vertical to the gravitational direction of the main body of projector111. For example, the following way may be used. That is, support plate121as a support mechanism is fastened to the top surface of the main body of projector111, and projection direction change device1is attached to screw hole123provided in support plate121with a screw. For ground-installed projector111horizontally placed, like projector system110C shown in modified example 3 ofFIG.13, projection direction change device1may be fastened to the top and bottom surfaces of the main body of projector111or of frame111b.

In the above-described embodiment, mirror26of projection direction change device1has a shape where the region opposite to projection lens unit113is larger than that closer to projection lens unit113, but the disclosure is not limited to this embodiment. The region opposite to projection lens unit113may be the same in size as that closer to projection lens unit113. Mirror26may be a rectangle for example.

Hereinbefore, the embodiments are described to exemplify the technology disclosed in this application. For this reason, the accompanying drawings and detailed descriptions are provided. Accordingly, some components described in the detailed descriptions and accompanying drawings may include, besides what is essential for solving problems, what is not essential in order to exemplify the above-described technologies. Hence, the fact that such inessential components are included in the detailed descriptions and accompanying drawings does not mean that such inessential components are immediately acknowledged as essential.

The above-described embodiments are for exemplification of the technologies in the disclosure. Hence, the embodiments may undergo various kinds of change, substitution, addition, and/or omission within the scope of the claims and their equivalent technology. Besides, some components described above can be combined to create a new embodiment.

Overview of Exemplary Embodiments

(1) A projection direction change device of the present disclosure includes a mirror that reflects light emitted from a projection lens unit of a projector; a mirror support part that rotatably supports the mirror around a first axis and a second axis; a first drive part that rotary drives the mirror around the first axis; and a second drive part that rotary drives the mirror around the second axis. Aa intersecting point of the first and second axes is positioned closer to the projection lens unit than a geometric barycenter of the mirror is.

Due to this configuration, the intersecting point of the first and second axes is positioned closer to the projection lens unit than the geometric barycenter of the mirror is. This can shorten than before the distance from the region of the mirror opposite to the projection lens unit to the projection lens unit even if the projection lens unit is spaced from the intersecting point of the two rotation axes to the degree that the end of the mirror closer to the projection lens unit does not interfere with the projection lens unit. This can suppress an increase of the size of an image projected into the region of the mirror opposite to the projection lens unit. This increases the rotation angle of the mirror to increase the range of changing projection directions of light from the projection lens unit, and the mirror can be downsized, as well as the projection direction change device and the image projection system.

(2) The projection direction change device of (1) includes a mirror frame to which the mirror is attached. The mirror support part rotatably supports the mirror frame to which the mirror has been attached around the first and second axes. Weight balance of the mirror frame has been adjusted so that a barycenter of the mirror frame to which the mirror has been attached is positioned closer to the intersecting point of the first and second axes than the geometric barycenter of the mirror is.

These configurations can reduce drive loads while the mirror and the mirror frame are rotary driven.

(3) In the projection direction change device of (2), the weight balance of the mirror frame has been adjusted so that the barycenter of the mirror frame to which the mirror has been attached is positioned at the intersecting point of the first and second axes.

These configurations minimize the drive load while the mirror and mirror frame are rotary driven.

(4) In the projection direction change device of (3), the mirror frame includes a rib for adjusting the weight balance.

(5) In the projection direction change device of any one of (2) to (4), the mirror frame has a through hole for adjusting the weight balance.

(6) In the projection direction change device of any one of (1) to (5), the mirror has a hexagonal shape in which a side closer to the projection lens unit is shorter than a side that is opposite to the projection lens unit and is counter to the side closer to the projection lens unit.

(7) The projection direction change device of any one of (1) to (6) includes a mirror controller that indicates a drive amount of the mirror to the first and second drive parts.

(8) The projection direction change device of (7) includes an attitude sensor that detects a state of an attitude of the mirror. The mirror controller adjusts a drive amount of the mirror based on the state of an attitude.

(9) The projection direction change device of any one of (1) to (8) includes a position adjustment mechanism that allows the mirror to be displaced along a direction of projection from the projection lens unit.

(10) An image projection system of the present disclosure includes the projection direction change device of (7) or (8); the projector that projects an image; an image output device that outputs an image to the projector; and a controller that sends a command signal about the attitude of the mirror to the mirror controller and outputs an image output signal synchronized with the command signal to the image output device.

(11) In the image projection system of (10), the projector includes a lens driver that moves some or all lenses in the projection lens unit along or in parallel with a projection direction. The lens driver adjusts a projection function of the projector in collaboration with drive control of the mirror of the projection direction change device based on a command signal from the controller.

(12) In the image projection system of (11), the lens driver performs zoom adjustment of the projection lens unit.

(13) In the image projection system of (11), the lens driver performs focus adjustment of the projection lens unit.

(14) In the image projection system of (11), the lens driver performs shift adjustment of the projection lens unit.

The present disclosure is applicable to a projection image apparatus such as a projection direction change device or a projector.