IMAGE PROJECTION APPARATUS AND IMAGE PROJECTION METHOD

An image projection apparatus includes a projector including a light source and an image generator configured to use light emitted from the light source to generate a projection image while moving between a plurality of image generation positions; an illuminance detector configured to detect illuminance in an environment in which the image projection apparatus is disposed; a control amount setter configured to set a non-projection time based on the illuminance detected by the illuminance detector; and a projection controller configured to control the projector so as not to generate the projection image during the non-projection time, while the image generator is moving between the plurality of image generation positions.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-142604, filed on Jul. 17, 2015. The contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image projection apparatus and an image projection method.

2. Description of the Related Art

In an image projection apparatus for projecting images onto a screen, etc., based on input image data, there is known a method of slightly shifting the projection image at high speed to increase the resolution of the projection image in a pseudo manner and improve the image quality.

For example, when the projection image is shifted between a plurality of projection positions, when an image is projected at a middle position between the projection positions, the effect of increasing the resolution of the projection image may be decreased. Thus, there is proposed an image display apparatus that implements control of not displaying projection images while the centroid of the pixels is moving and during a stable period until a predetermined pixel is displayed (see, for example, Patent Document 1).

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-180011

SUMMARY OF THE INVENTION

An aspect of the present invention provides an image projection apparatus and an image projection method in which one or more of the above-described disadvantages are eliminated.

According to one aspect of the present invention, there is provided an image projection apparatus including a projector including a light source and an image generator configured to use light emitted from the light source to generate a projection image while moving between a plurality of image generation positions; an illuminance detector configured to detect illuminance in an environment in which the image projection apparatus is disposed; a control amount setter configured to set a non-projection time based on the illuminance detected by the illuminance detector; and a projection controller configured to control the projector so as not to generate the projection image during the non-projection time, while the image generator is moving between the plurality of image generation positions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A problem to be solved by an embodiment of the present invention is to provide an image projection apparatus by which the resolution of projection images can be increased and images can be projected at a brightness level according to the environment.

A description will be given of embodiments with reference to the accompanying drawings.

FIG. 1is a diagram showing a projector1which is an image projection apparatus according to an embodiment.

As shown inFIG. 1, the projector1includes a radiation window3, an illuminance meter6, and an external interface (I/F)9, and an optical engine which is configured to generate a projection image P is provided in the inside of the projector1. For example, when image data is transmitted to the projector1from a personal computer (PC) or a digital camera connected to the external interface9, the optical engine generates an image based on the received image data and projects the projection image P from the radiation window3onto a screen S as shown inFIG. 1.

Note that, in the following drawings, X1-X2directions represent width directions of the projector1, Y1-Y2directions represent height directions of the projector1, and Z1-Z2directions represent depth directions of the projector1. Moreover, in the following description, it is assumed that the radiation window3side of the projector1corresponds to the top of the projector1and the side of the projector1opposite to the radiation window3corresponds to the bottom of the projector1.

FIG. 2is a block diagram showing a functional configuration of the projector1.

As shown inFIG. 2, the projector1includes a power source4, a main switch (SW)5, the illuminance meter6, an operation unit7, an external interface (I/F)9, a system control unit10, a fan20, and an optical engine15.

The power source4is connected to a commercial power source, converts voltage and frequency of the commercial power for the internal circuits of the projector1, and supplies the resulting power to each of the system control unit10, the fan20, and the optical engine15.

The main switch5is switched ON or OFF by a user to power on or off the projector1. While the power source4is connected to the commercial power source via a power cord, if the main switch5is switched ON, the power source4starts supplying power to the respective components of the projector1, and if the main switch5is switched OFF, the power source4stops the power supply to the respective components of the projector1.

The illuminance meter6is an example of an illuminance detector. The illuminance meter6detects the illuminance of the environment where the projector1is installed. Note that the illuminance meter6of this embodiment is provided integrally with the projector1and is provided for detecting the illuminance around the projector1. However, the illuminance meter6may be provided as a separate body from the projector1. When the illuminance meter6is provided as a separate body from the projector1, for example, the illuminance meter6may be disposed near the screen S, and the illuminance meter6will be able to detect the illuminance around the plane of projection. The projector1can execute various control operations based on the illuminance detection result around the plane of projection sent from the illuminance meter6, and optimize the projection image.

The operation unit7includes buttons configured to receive various input operations by a user. For example, the operation unit7is provided on a top surface of the projector1. The operation unit7is configured to receive input operations by the user, such as selection of a size of a projection image, selection of a color tone, and adjustment of a focus. The user's input operation received by the operation unit7is sent to the system control unit10.

The external interface9includes connection terminals connected to, for example, a personal computer (PC) or a digital camera, and is configured to supply image data, which is received from the connected apparatus, to the system control unit10.

The system control unit10includes an image control unit11and a movement control unit12. For example, the system control unit10may include a CPU (a processor), a ROM, and a RAM as hardware components thereof. The functions of the system control unit10may be implemented by instructions from the CPU when a program read from the ROM into the RAM is executed by the CPU.

The image control unit11is configured to control a digital micromirror device (DMD)551provided in an image displaying unit50of the optical engine15based on the image data received from the external interface9, to generate an image to be projected on the screen S.

The movement control unit12is configured to move a movable unit55(which is provided to be movable in the image displaying unit50) and control a position of the DMD551provided in the movable unit55. The movable unit55is an example of a movable member.

The fan20is rotated under the control of the system control unit10to cool a light source30of the optical engine15.

The optical engine15includes the light source30, a lighting optical system unit40, the image displaying unit50, and a projection optical system unit60. The optical engine15is controlled by the system control unit10to project an image on a screen S as shown inFIG. 1.

Examples of the light source30include a mercury high-pressure lamp, a xenon lamp, and a light emitting diode (LED). The light source30is controlled by the system control unit10to emit light to the lighting optical system unit40.

The lighting optical system unit40includes, for example, a color wheel, a light tunnel, and relay lenses. The lighting optical system unit40is configured to guide the light emitted from the light source30to the DMD551provided in the image displaying unit50.

The image displaying unit50includes a fixed unit51which is fixed and supported on the image displaying unit50, and the movable unit55which is provided to be movable relative to the fixed unit51. The fixed unit51is an example of a fixed member. The movable unit55includes the DMD551and a position of the movable unit55relative to the fixed unit51is controlled by the movement control unit12of the system control unit10. The DMD551is an example of an image generator. The DMD551is controlled by the image control unit11of the system control unit10. The DMD551is configured to modulate the light received from the lighting optical system unit40and generate a projection image based on the received light.

The projection optical system unit60includes, for example, a plurality of projection lenses and a mirror. The projection optical system unit60is configured to enlarge the image generated by the DMD551of the image displaying unit50, and project the enlarged image on the screen S.

Next, a configuration of the optical engine15of the projector1is explained.

FIG. 3is a perspective view of the optical engine15of the projector1. As shown inFIG. 3, the optical engine15includes the light source30, the lighting optical system unit40, the image displaying unit50, and the projection optical system unit60. The optical engine15is provided in the inside of the projector1.

The light source30is provided on a side surface of the lighting optical system unit40. The light source30is configured to emit light in the X2direction. The lighting optical system unit40is configured to guide the light emitted from the light source30to the image displaying unit50. The image displaying unit50is provided beneath the lighting optical system unit40. The image displaying unit50is configured to generate a projection image based on the light received from the lighting optical system unit40. The projection optical system unit60is provided above the lighting optical system unit40. The projection optical system unit60is configured to project the projection image generated by the image displaying unit50onto the screen S which is provided outside the projector1.

The optical engine15of this embodiment is configured to project the image based on the light emitted from the light source30in an upward direction. Alternatively, the optical engine15may be configured to project the image in a horizontal direction.

FIG. 4is a diagram showing the lighting optical system unit40. As shown inFIG. 4, the lighting optical system unit40includes a color wheel401, a light tunnel402, relay lenses403and404, a cylinder mirror405, and a concave mirror406.

The color wheel401is, for example, a disc-like component in which color filters of R (red), G (green), and B (blue) are provided at different portions in a circumferential direction thereof. The color wheel401is rotated at high speed so that the light emitted from the light source30is divided into RGB color light beams in a time-division manner.

The light tunnel402is, for example, a rectangular tube-like component formed of bonded glass sheets. The light tunnel402functions to perform multipath reflection of the RGB color light beams passing through the color wheel401by the internal surfaces thereof for equalization of luminance distribution, and guides the resulting light beams to the relay lenses403and404.

The relay lenses403and404function to correct the chromatic aberrations on the optical axis of the light beams emitted from the light tunnel402and convert the light beams into converging light beams.

The cylinder mirror405and the concave mirror406function to reflect the light emitted from the relay lens404to the DMD551provided in the image displaying unit50. The DMD551is configured to modulate the light reflected from the concave mirror406and generate a projection image.

FIG. 5is a diagram showing an internal configuration of the projection optical system unit60. As shown inFIG. 5, the projection optical system unit60includes projection lenses601, a folding mirror602, and a curved surface mirror603which are provided in a housing of the projection optical system unit60.

The projection lenses601include a plurality of lenses. The projection lenses601function to focus the projection image generated by the DMD551of the image displaying unit50onto the folding mirror602. The folding mirror602and the curved surface mirror603function to reflect the focused projection image so as to be enlarged, and project the resulting image on the screen S which is provided outside the projector1.

FIG. 6is a perspective view of the image displaying unit50.FIG. 7is a side view of the image displaying unit50.

As shown inFIG. 6andFIG. 7, the image displaying unit50includes the fixed unit51which is fixed and supported, and the movable unit55which is provided to be movable to the fixed unit51.

The fixed unit51includes a top plate511as a first fixed member, and a base plate512as a second fixed member. In the fixed unit51, the top plate511and the base plate512are held in parallel and face each other via a predetermined gap between them. The fixed unit51is fixed to the bottom of the lighting optical system unit40.

The movable unit55includes the DMD551, a movable plate552as a first movable member, a joint plate553as a second movable member, and a heat sink554. The movable unit55is supported to be movable relative to the fixed unit51by the fixed unit51.

The movable plate552is provided between the top plate511and the base plate512of the fixed unit51. The movable plate552is supported by the fixed unit51to be movable in a direction which is parallel to the top plate511and the base plate512and parallel to the surface of the movable plate552.

The joint plate553is fixed to the movable plate552with the base plate512of the fixed unit51being inserted between the movable plate552and the joint plate553. The DMD551is fixed to a top surface of the joint plate553, and the heat sink554is fixed to a bottom surface of the joint plate553. The joint plate553, which is fixed to the movable plate552, is supported by the fixed unit51to be movable relative to the fixed unit51integrally with the movable plate552, the DMD551, and the heat sink554.

The DMD551is mounted on a surface of the joint plate553on the movable plate552side. The DMD551is provided to be movable integrally with the movable plate552and the joint plate553. The DMD551includes an image generation surface on which a plurality of rotatable micromirrors are arrayed in a lattice formation. A specular surface of each of the micromirrors of the DMD551is provided to be slantingly rotatable around a twist shaft. The ON/OFF drive of the micromirrors of the DMD551is performed based on an image signal transmitted from the image control unit11of the system control unit10.

For example, in an ON state, an inclination angle of a micromirror is controlled so that the micromirror reflects the light from the light source30to the projection optical system unit60, and in an OFF state, the inclination angle of the micromirror is controlled so that the micromirror reflects the light from the light source30to an OFF light plate (which is not illustrated).

In this manner, the inclination angle of each of the micromirrors of the DMD551is controlled based on the image signal transmitted from the image control unit11, and the light emitted from the light source30and passing through the lighting optical system unit40is modulated and a projection image is generated by the DMD551.

The heat sink554is an example of a heat dissipation unit. The heat sink554is provided so that the heat sink554at least partially contacts the DMD551. Integrally with the DMD551, the heat sink554is mounted on the joint plate553which is supported to be movable, and it is possible to efficiently cool the DMD551by the contact of the heat sink554with the DMD551. By this configuration of the heat sink554, the projector1is capable of preventing the temperature of the DMD551from increasing and capable of reducing problems, such as malfunction and failure, due to the temperature rise of the DMD551.

FIG. 8is a perspective view of the fixed unit51.FIG. 9is an exploded perspective view of the fixed unit51.

As shown inFIG. 8andFIG. 9, the fixed unit51includes the top plate511and the base plate512. The top plate511and the base plate512are made of a flat-shaped plate material. The top plate511has a central hole513formed in a position corresponding to the DMD551of the movable unit55. The base plate512has a central hole514formed in a position corresponding to the DMD551of the movable unit55. The top plate511and the base plate512are supported by plural supports515so that the top plate511and the base plate512are held in parallel and face each other via the predetermined gap between them.

As shown inFIG. 9, an upper end portion of each of the supports515is press fitted in a corresponding one of support holes516which are formed in the top plate511, and a lower end portion of the support515is inserted in a corresponding one of support holes517which are formed in the base plate512. The lower end portion of each of the supports515is formed with an external thread groove. The supports515support the top plate511and the base plate512so that the top plate511and the base plate512are held in parallel and face each other via the predetermined gap between them.

Moreover, support holes522are formed in the top plate511to hold support balls521rotatably, and support holes526are formed in the base plate512to hold support balls521rotatably.

Cylindrical holding members523each of which has an internal thread groove formed in an inner peripheral surface of the holding member523are inserted in the support holes522of the top plate511. The holding members523hold the support balls521rotatably, respectively: Positioning screws524are inserted into upper end portions of the holding members523, respectively. Lower end faces of the support holes526of the base plate512are closed by lid members527and528, and the support holes526of the base plate512hold the support balls521rotatably.

The support balls521which are rotatably held by the support holes522and526of the top plate511and the base plate512are respectively in contact with the movable plate552provided between the top plate511and the base plate512. Hence, the support balls521movably support the movable plate552.

FIG. 10is a diagram showing a support structure of the movable plate552by the fixed unit51.FIG. 11is an enlarged diagram showing a portion (indicated by the letter “A” inFIG. 10) of the support structure of the movable plate552by the fixed unit51.

As shown inFIG. 10andFIG. 11, in the top plate511, the support balls521are rotatably held by the holding members523which are inserted in the support holes522. In the base plate512, the support balls521are rotatably held by the support holes526the lower end faces of which are closed by the lid members527and528.

Each of the support balls521is held so that the support ball521projects at least partially from the support hole522or the support hole526. Each of the support balls521contacts the movable plate552provided between the top plate511and the base plate512to support the movable plate552. The top surface and the bottom surface of the movable plate552are supported by the rotatably held support balls521so that the movable plate552is movable in the direction which is parallel to the top plate511and the base plate512and parallel to the top and bottom surfaces of the movable plate552.

Moreover, the amount of projection of the support ball521(provided on the top plate511side) from the lower end of the holding member523is varied depending on a position of the positioning screw524(which contacts the support ball521on the side opposite to the movable plate552). For example, if the positioning screw524is displaced in the Z1direction (upward), the amount of projection of the support ball521is decreased and the gap between the top plate511and the movable plate552is decreased. On the other hand, if the positioning screw524is displaced in the Z2direction (downward), the amount of projection of the support ball521is increased and the gap between the top plate511and the movable plate552is increased.

Hence, the gap between the top plate511and the movable plate552may be appropriately adjusted by changing the amount of projection of the support ball521using the positioning screw524.

Moreover, as shown inFIG. 8andFIG. 9, magnets531,532,533and534are mounted on a bottom surface of the top plate511on the base plate512side.

FIG. 12is a bottom view of the top plate511. As shown inFIG. 12, the magnets531,532,533and534are mounted on the bottom surface of the top plate511on the base plate512side.

The magnets531,532,533and534are provided at four locations which surround the central hole513of the top plate511. Each of the magnets531,532,533and534is made of a pair of magnet pieces having a rectangular parallelepiped shape. The two magnet pieces of each pair are arranged side by side so that longitudinal directions of the two magnet pieces are parallel to each other. Each of the magnets531,532,533and534forms a magnetic field which functions to attract the movable plate552.

Coils are provided on the top surface of the movable plate552to face the magnets531,532,533and534, respectively. The magnets531,532,533and534on the top plate511and the corresponding coils on the movable plate552constitute a movement device configured to move the movable plate552.

Note that the number and positions of the supports515and the support balls521which are provided on the fixed unit51are not limited to the configuration of this embodiment, and it is sufficient that the supports515and the support balls521are provided to support the movable plate552movably.

FIG. 13is a perspective view of the movable unit55.FIG. 14is an exploded perspective view of the movable unit55. As shown inFIG. 13andFIG. 14, the movable unit55includes the DMD551, the movable plate552, the joint plate553, the heat sink554, a holding member555, and a DMD base557. The movable unit55is supported to be movable relative to the fixed unit51.

As described above, the movable plate552is provided between the top plate511and the base plate512of the fixed unit51and supported by the support balls521to be movable in the direction parallel to the top and bottom surfaces of the movable plate552.

FIG. 15is a perspective view of the movable plate552. As shown inFIG. 15, the movable plate552is made of a flat-shaped plate material. The movable plate552has a central hole570in the position corresponding to the DMD551which is mounted on the DMD base557, and coils581,582,583and584are formed on the periphery of the central hole570.

Each of the coils581,582,583and584is formed of electric wires wound around a shaft parallel to the Z1-Z2directions. The coils581,582,583and584are provided in recesses formed in the bottom surface of the top plate511on the movable plate552side, and the coils are enclosed with coverings. The coils581,582,583and584on the movable plate552and the magnets531,532,533and534on the top plate511constitute the movement device configured to move the movable plate552.

In the state in which the movable unit55is supported by the fixed unit51, the magnets531,532,533and534on the top plate511and the coils581,582,583and584on the movable plate552are provided to face each other, respectively. When electric current flows through the coils581,582,583and584, Lorentz forces as driving forces to move the movable plate552are generated by the magnetic fields formed by the coils581,582,583and584and the magnets531,532,533and534.

The movable plate552is linearly moved or rotated to the fixed unit51within an XY plane by the Lorentz forces as the driving forces which are generated by the magnets531,532,533and534and the coils581,582,583and584.

The magnitude and direction of the current flowing through each of the coils581,582,583and584are controlled by the movement control unit12of the system control unit10. The movement control unit12controls the direction of movement (or rotation), the amount of movement and the rotational angle of the movable plate552by changing the magnitude and direction of the current flowing through each of the coils581,582,583and584.

In this embodiment, the coil581and the magnet531, and the coil584and the magnet534are arranged to face each other in the X1and X2directions, and the coils581and584and the magnets531and534are formed as a first drive unit. If electric current flows through the coils581and584, Lorentz forces in the X1or X2direction are generated as shown inFIG. 15. The movable plate552is moved in the X1or X2direction by the Lorentz force generated by the coil581and the magnet531and the Lorentz force generated by the coil584and the magnet534.

Moreover, in this embodiment, the coil582and the magnet532, and the coil583and the magnet533are arranged side by side in the X1or X2direction as a second drive unit, and the longitudinal direction of the magnets532and533is arranged to be perpendicular to the longitudinal direction of the magnets531and534. If electric current flows through the coil582and the coil583, Lorentz forces in the Y1or Y2direction are generated as shown inFIG. 15.

The movable plate552may be moved in the Y1or Y2direction by the Lorentz force generated by the coil582and the magnet532and the Lorentz force generated by the coil583and the magnet533with the directions of the Lorentz forces being the same. Moreover, the movable plate552may be rotated in the XY plane by the Lorentz force generated by the coil582and the magnet532, and the Lorentz force generated by the coil583and the magnet533with the directions of the Lorentz forces being opposite to each other.

For example, if electric current is supplied so that a Lorentz force in the Y1direction is generated by the coil582and the magnet532and a Lorentz force in the Y2direction is generated by the coil583and the magnet533, the movable plate552is rotated clockwise in a top view. On the other hand, if electric current is supplied so that a Lorentz force in the Y2direction is generated by the coil582and the magnet532and a Lorentz force in the Y1direction is generated by the coil583and the magnet533, the movable plate552is rotated counterclockwise in a top view.

In the movable plate552, movable range restriction holes571are formed at locations corresponding to the supports515of the fixed unit51. The supports515of the fixed unit51are inserted in the movable range restriction holes571. If the movable plate552is greatly moved due to vibration or certain malfunction, the supports515come in contact with the movable range restriction holes571, and the movable range of the movable plate552may be restricted.

As described above, in this embodiment, the movement control unit12of the system control unit10is configured to move the movable plate552to an arbitrary position within the movable range by controlling the magnitude and directions of the current flowing through the coils581,582,583and584.

Note that the number and positions of the coils581,582,583and584and the magnets531,532,533and534, which constitute the movement device, are not limited to this embodiment. Another embodiment different from this embodiment may be used if the movable plate552can be moved to an arbitrary position. For example, the magnets in the movement device may be mounted on the top surface of the top plate511, or mounted on any of the surfaces of the base plate512. Alternatively, the magnets may be mounted on the movable plate552, and the coils may be mounted on the top plate511or the base plate512.

Moreover, the number, the positions, and the shape of the movable range restriction holes571are not limited to the configuration of this embodiment. For example, one movable range restriction hole or plural movable range restriction holes571may be provided. The movable range restriction holes571may have a rectangular or circular shape.

As shown inFIG. 13, the joint plate553is fixed to the bottom surface of the movable plate552(on the base plate512side), and the movable plate552is movably supported by the fixed unit51. The joint plate553is made of a flat-shaped plate material. The joint plate553has a central hole in the position corresponding to the DMD551. Folded portions provided on the periphery of the joint plate553are fixed to the bottom surface of the movable plate552by three screws591(seeFIG. 13).

FIG. 16is a perspective view of the movable unit55from which the movable plate552is removed. As shown inFIG. 16, the DMD551is mounted on the top surface of the joint plate553and the heat sink554is mounted on the bottom surface of the joint plate553. The joint plate553, which is fixed to the movable plate552, is provided to be movable relative to the fixed unit51according to the movement of the movable plate552integrally with the DMD551and the heat sink554.

The DMD551is mounted on the DMD base557, and the DMD base557is interposed between the holding member555and the joint plate553. Hence, the DMD551is fixed to the joint plate553via the DMD base557. As shown inFIG. 14andFIG. 16, the holding member555, the DMD base557, the joint plate553, and the heat sink554are laminated and fixed by shoulder screws560(which are fastener members) and springs561(which are pressure units).

FIG. 17is a diagram showing a DMD holding structure of the movable unit55.FIG. 17is a side view of the movable unit55, and inFIG. 17, the illustration of the movable plate552and the joint plate553is omitted.

As shown inFIG. 17, the heat sink554includes a projection554awhich contacts the bottom surface of the DMD551via a through hole formed in the DMD base557when the heat sink554is fixed to the joint plate553. Note that, alternatively, the projection554aof the heat sink554may be a projection provided on the bottom surface of the DMD base557to contact the position of the heat sink554corresponding to the DMD551.

In order to increase the effect of cooling the DMD551by the heat sink554, a heat transfer sheet that is elastically deformable may be interposed between the projection554aof the heat sink554and the DMD551. In such a case, the thermal conductivity between the projection554aof the heat sink554and the DMD551will be increased by the heat transfer sheet, and thereby the effect of cooling the DMD551by the heat sink554will be increased.

As described above, the holding member555, the DMD base557, and the heat sink554are laminated and fixed by the shoulder screws560and the springs561. If the shoulder screws560are tightened, the springs561are compressed in the Z1-Z2directions, and a force F1in the Z1direction (as indicated inFIG. 17) is produced by the spring561. The heat sink554is pressed onto the DMD551by a force F2in the Z1direction which is the resultant of the forces F1produced by the springs561.

In this embodiment, the shoulder screws560and the springs561are provided at four locations, and the force F2acting on the heat sink554is equal to the resultant of the forces F1produced by the four springs561. The force F2from the heat sink554is exerted on the holding member555which holds the DMD base557on which the DMD551is mounted. As a result, a reaction force F3in the Z2direction equivalent to the force F2from the heat sink554is exerted on the holding member555, so that the DMD base557can be held between the holding member555and the joint plate553.

A force F4in the Z2direction acts on the shoulder screws560and the springs561due to the force F3acting on the holding member555. Because the springs561are provided at four locations, the force F4acting on each of the springs is equivalent to one fourth (¼) of the force F3acting on the holding member555, and the force F4and the force F1are in equilibrium.

The holding member555is formed like a leaf spring and made of a material which can be bent as indicated by the arrow B inFIG. 17. The holding member555is bent by the upward force from the projection554aof the heat sink554, the downward force to push back the heat sink554in the Z2direction is produced by the holding member555, and firm contact between the DMD551and the heat sink554can be maintained.

As described above, in the movable unit55, the movable plate552and the joint plate553(on which the DMD551and the heat sink554are mounted) are movably supported by the fixed unit51. The position of the movable unit55is controlled by the movement control unit12of the system control unit10. Moreover, the heat sink554contacting the DMD551by pressure is mounted on the movable unit55, and the projector1is capable of having reduced problems, such as malfunction and failure, due to the temperature rise of the DMD551.

As described above, in the projector1of this embodiment, the DMD551which generates a projection image is mounted on the movable unit55, and the position of the DMD551is controlled by the movement control unit12of the system control unit10together with the movable unit55.

For example, the movement control unit12controls the position of the movable unit55by a high speed movement between positions lying apart by a distance less than the array interval of the micromirrors of the DMD551at a predetermined cycle corresponding to a frame rate during image projection. At this time, the image control unit11transmits an image signal to the DMD551to generate a projection image shifted according to each of the positions.

For example, the movement control unit12performs reciprocation movement of the DMD551between two positions lying apart by the distance less than the array interval of the micromirrors of the DMD551in the X1-X2directions and the Y1-Y2directions at the predetermined cycle. At this time, the image control unit11controls the DMD551to generate a projection image shifted according to each of the positions, and it is possible to make the resolution of the projection image to be twice the resolution of the DMD551. Moreover, the resolution of the projection image can be made to be more than twice the resolution of the DMD551by increasing the movement range of the DMD551.

The movement control unit12moves the DMD551and the movable unit55at the predetermined cycle and the image control unit11controls the DMD551to generate the projection image according to the position. Hence, it is possible to obtain the resolution of the projection image which is higher than the resolution of the DMD551.

In the projector1of this embodiment, the movement control unit12controls the DMD551so that the DMD551is rotated integrally with the movable unit55, and the projection image can be rotated without reducing the size of the projection image. For example, in a conventional projector in which an image generation unit, such as a DMD, is fixed, if the size of a projection image is not reduced, the projection image cannot be rotated while maintaining the aspect ratio of the projection image. In contrast, in the projector1of this embodiment, the DMD551can be rotated, and the rotation of the DMD551and the adjustment of the inclination can be performed without reducing the size of the projection image.

As described in the foregoing, in the projector1of this embodiment, the movement of the DMD551is possible, and it is possible to provide an increased resolution of the projection image. Moreover, the DMD551and the heat sink554to cool the DMD551are mounted on the movable unit55, the heat sink554is brought in contact with the DMD551, the effect of cooling the DMD551by the heat sink554is increased, and the temperature rise of the DMD551is prevented. Hence, the projector1is capable of having reduced problems, such as malfunction and failure, due to the temperature rise of the DMD551.

FIG. 18is a block diagram illustrating a functional configuration of the projector1of this embodiment.

As illustrated inFIG. 18, the projector1includes the image control unit11, the movement control unit12, a projection control unit13, a control amount setting unit14, a control amount storage unit16, and an illuminance detecting unit17.

The image control unit11controls the DMD551based on image data that is input, to generate an image to be projected onto the screen S. The image control unit11controls each of the micromirrors of the DMD551, to generate a projection image according to a position of the DMD551that is displaced by being controlled by the movement control unit12.

The movement control unit12displaces the movable unit55in which the DMD551is included, to move the DMD551together with the movable unit55. For example, as described above, the movement control unit12performs reciprocation movement of the DMD551between two positions lying apart by the distance less than the array interval of the micromirrors of the DMD551at the predetermined cycle. The two positions are an image generation position P1and an image generation position P2. Note that in the following description, the image generation position P1and the image generation position P2may be simply referred to as a position P1and a position P2.

FIG. 19is a diagram illustrating an example of a projection image according to an embodiment. InFIG. 19, a projection image P11is formed by projecting an image generated at the position P1by the DMD551. Furthermore, a projection image P12indicated by dashed lines is an image formed by projecting an image generated at the position P2by the DMD551.

The projection image P11and the projection image P12are formed by a plurality of pixels in a square shape including one side having a length XL in the X direction and another side having a length YL in the Y direction inFIG. 19. The pixels in the projection image P11and the projection image P12are formed to correspond to the plurality of micromirrors disposed in the DMD551.

As illustrated inFIG. 19, for example, the movement control unit12performs a reciprocation movement of the DMD551between the position P1and the position P2, to displace the pixels in a projection image P by half a pixel in the X direction and the Y direction (XL/2 in the X direction and YL/2 in the Y direction).

The projection control unit13controls the optical engine15that is a projector, such that an image is not projected during a non-projection time set by the control amount setting unit14, while the DMD551moves between the position P1and the position P2.

The projection control unit13controls the optical engine15, for example, such that the light source30is turned off during the non-projection time. When the light source30is turned off, a projection image is not generated at the DMD551, and an image is not projected to the screen from the projector1. Furthermore, the projection control unit13may control the micromirrors of the DMD551such that the DMD551reflects the light from the light source30toward the OFF light plate during the non-projection time. In this case, light is not guided from the DMD551to the projection optical system unit60and an image is not projected from the projector1to the screen.

Here,FIGS. 20 and 21are diagrams illustrating examples of pixels forming the projection images. InFIGS. 20 and 21, a pixel Pi1is a pixel included in the projection image P11generated at the position P1by the DMD551. A pixel Pi2is a pixel included in the projection image P12generated at the position P2by the DMD551. Furthermore, the pixel Pi1and the pixel Pi2are pixels generated by the same micromirror in the DMD551that performs a reciprocation movement between the position P1and the position P2, and the state of the pixel illustrated by hatching expresses a state where an image is projected.

FIG. 20is a diagram of an example where control is implemented such that an image is projected only while the DMD551is at the position P1or the position P2, and an image is not projected while the DMD551is moving between the position P1and the position P2. As described above, by implementing control such that an image is not projected while the DMD551is moving, it is possible to form the projection image P11and the projection image P12according to the position P1and the position P2, and increase the resolution of the projection image P. However, an image is not projected while the DMD551is moving between the position P1and the position P2, and therefore, for example, when the environment where the projector1is installed is bright, the projection image P may be dark and difficult to view.

On the other hand,FIG. 21is a diagram illustrating an example where control is implemented such that an image is constantly projected even while the DMD551is moving between the position P1and the position P2. In this way, by projecting an image even while the DMD551is moving, the brightness level of the projection image P can be maintained. However, in this case, the pixel Pi1and the pixel Pi2are coupled in the projection image P, and therefore the effect of increasing the resolution by shifting the projection image P may decrease and the image quality may decrease.

Therefore, in this embodiment, the control amount setting unit14sets a non-projection time in which images are not projected while the DMD551is moving, such that the resolution of the projection image P can be increased and the brightness level of the projection image P can be maintained.

The control amount setting unit14acquires the illuminance measured by the illuminance meter6from the illuminance detecting unit17, and acquires the non-projection time and the light quantity of the light source30corresponding to the illuminance as control amounts, from the control amount storage unit16storing a control table in which non-projection times are stored in association with the illuminance.

The control amount storage unit16stores a control table including the non-projection time and the light quantity of the light source30, by which the resolution of the projection image P can be increased and the projection image P can be maintained at a brightness level that is easy to view, according to the illuminance measured by the illuminance meter6. The control amount setting unit14acquires the non-projection time and the light quantity of the light source30corresponding to the illuminance from the control table stored in the control amount storage unit16. The control amount setting unit14sets the acquired control amounts in the projection control unit13.

The projection control unit13implements controls such that the optical engine15does not project images while the DMD551is moving between the position P1and the position P2, for example, by turning off the light source30during the non-projection time set by the control amount setting unit14.

FIG. 22is a graph illustrating an example of the displacement amount of the DMD551and the non-projection time. In the graph in the top stage ofFIG. 22, the horizontal axis indicates the time and the vertical axis indicates the displacement amount of the DMD551from the position P1. Furthermore, the bottom stage inFIG. 22illustrates a timing chart of turning on or off the light source30.

As illustrated in the graph in the top stage ofFIG. 22, the DMD551is controlled by the movement control unit12to perform a reciprocation movement between the position P1(displacement amount is zero) and the position P2(displacement amount is Lxy). Furthermore, while the DMD551is moving between the position P1and the position P2, the projection control unit13implements control such that the light source30is turned off during a non-projection time TOFFset by the control amount setting unit14. As the light source30is turned off while the DMD551is moving, the resolution of the projection image P can be increased.

Here, the control table stored in the control amount storage unit16is set such that the non-projection time TOFFdecreases as the illuminance detected by the illuminance meter6increases, and the non-projection time TOFFincreases as the illuminance decreases.

As illustrated inFIG. 23, when the illuminance measured by the illuminance meter6is high, control is implemented to decrease the non-projection time TOFFand increase the time of projecting images, such that the brightness level of the projection image P is increased. As the brightness level of the projection image P increases, even when the lighting, etc., in a room where the projector1is installed is bright, the projection image P projected by the projector1can be easily viewed.

However, if the non-projection time TOFFis excessively decreased, the images will be projected in a state where the pixels are nearly coupled as illustrated inFIG. 21. Consequently, the effect of increasing the resolution of the projection image P may be decreased. Therefore, the non-projection time TOFFis required to be set within a range where the effect of increasing the resolution of the projection image P can be obtained. Furthermore, when the non-projection time TOFFis set to be as short as possible, and the brightness level of the projection image P is to be further increased, the projection control unit13controls the light source30to emit light by the light quantity set in the control amount setting unit14.

As described above, when the environment where the projector1is installed is bright, the non-projection time TOFFis decreased and the projection time is increased within a range where the resolution of the projection image P can be increased. Accordingly, it is possible to increase the resolution of the projection image P and also increase the brightness level of the projection image P such the image can be easily viewed.

Furthermore, as illustrated inFIG. 24, when the illuminance measured by the illuminance meter6is low, the non-projection time TOFFis increased within a range where the projection image does not become too dark and difficult to view. By increasing the non-projection time TOFFand decreasing the time of projecting images, and generating images at the DMD551only while the DMD551is near the position P1and the position P2, the effect of increasing the resolution of the projection image P can be maximized and the image quality of the projection image P can be further improved. Furthermore, when the environment where the projector1is installed is dark, even when the non-projection time TOFFis increased and the brightness level of the projection image P is decreased, the ease of viewing the projection image P can be maintained.

As described above, when the environment where the projector1is installed is dark, by increasing the non-projection time TOFFand decreasing the projection time of images, the brightness level of the projection image P can be decreased within a range where the projection image P does not become difficult to view, the resolution of the projection image P can be increased, and the image quality can be improved.

Note that as the light source30, for example, an LED is preferably used because the light quantity can be adjusted and the light can be turned on and off at high speed. However, as long as the light quantity can be adjusted and the light can be turned on and off at high speed, the light source30is not limited to an LED.

FIG. 25is a flowchart of an example of a projection control process according to an embodiment. The projection control process illustrated inFIG. 25is executed at a predetermined cycle while the projector1is projecting images. Furthermore, the projection control process may be executed at any timing according to an operation by the user.

In the projection control process according to this embodiment, first, in step S101, the illuminance meter6detects the illuminance in the environment where the projector1is installed, and the illuminance detecting unit17acquires the illuminance detection result from the illuminance meter6.

Next, in step S102, the control amount setting unit14acquires, from the control amount storage unit16, the control amount corresponding to the illuminance acquired by the illuminance detecting unit17. The control amount setting unit14acquires the non-projection time TOFFand the light quantity of the light source30corresponding to the illuminance, from a control table stored in the control amount storage unit16.

As described above, the control amount storage unit16stores a control table in which the illuminance and the non-projection time TOFFare associated with each other, such that the non-projection time TOFFdecreases as the illuminance increases and the non-projection time TOFFincreases as the illuminance decreases. Note that the control amount setting unit14may obtain the non-projection time TOFFcorresponding to the illuminance, for example, based on a calculating formula set in advance.

In step S103, the control amount setting unit14sets the non-projection time TOFFacquired from the control amount storage unit16, in the projection control unit13. The projection control unit13controls the optical engine15not to project images during the set non-projection time TOFF. For example, the projection control unit13turns off the light source30or controls the micromirrors such that the DMD551reflects the light from the light source30toward the OFF light plate.

In step S104, the control amount setting unit14sets the light quantity of the light source30acquired from the control amount storage unit16, in the projection control unit13. The projection control unit13controls the light source30to emit light by the set light quantity.

By repeatedly executing the above projection control process while the projector1is projecting images, the resolution of the projected images is increased and the images can be projected at a brightness level according to the environment where the projector1is installed.

As described above, the projector1according to this embodiment implements control such that images are not projected during the set non-projection time TOFFwhile the DMD551is moving between the position P1and the position P2. Accordingly, the resolution of the projection image P can be increased and the image quality can be improved. Furthermore, the non-projection time TOFFis set according to the illuminance of the environment where the projector1is installed, and therefore images can be projected at a brightness level according to the environment.

Note that in the above embodiment, a description is given of a case where the DMD551performs a reciprocation movement between the position P1and the position P2. However, the DMD551may be controlled to move among three or more positions. In this case also, as described in the above embodiment, by implementing control such that images are not projected during the non-projection time, which is set according to the illuminance of the environment where the projector is installed, while the DMD551is moving among the image generation positions, the resolution of the projection image P can be increased and images can be projected at a brightness level according to the environment in which the projector is installed.

According to one embodiment of the present invention, an image projection apparatus, by which the resolution of a projection image is increased and an image can be projected at a brightness level according to the environment, is provided.

The image projection apparatus and the image projection method are not limited to the specific embodiments described in the detailed description, and variations and modifications may be made without departing from the spirit and scope of the present invention.