Optical device having reflecting member attached to housing and projector having optical device

An optical device includes: a housing; and a reflection member disposed at a predetermined position within the housing, the housing includes a receiving opening through which the reflection member is inserted to be accommodated in the housing, and an attachment unit to which the reflection member is attached, the reflection member includes a front portion which has a reflection area for reflecting supplied light, a back portion positioned on the side opposite to the front portion, and a fixing unit positioned within the surface of the back portion and fixed to the attachment unit, and the fixing unit has an opening into which a position control jig inserted in an attachment direction of attaching the reflection member to the attachment unit through the receiving opening is inserted.

The entire disclosure of Japanese Patent Application No. 2009-032173, filed Feb. 16, 2009, is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to an optical device and a projector including the optical device.

2. Related Art

A projector which includes a light source, a light modulation device for modulating light emitted from the light source to form image light corresponding to image information, and a projection device for expanding and projecting the image light thus formed on a projection surface such as a screen is known. This type of projector further includes an optical device which has a lens unit for equalizing the amount of light emitted from the light source within a transmission area of the lens unit, a plurality of optical components such as a reflection member for changing the optical path of the light, and an optical component housing for accommodating the plural optical components. The respective optical components are disposed at predetermined positions on an illumination optical axis set inside the optical component housing.

Among these optical components, the reflection member for changing the optical path of the entering light needs to be appropriately positioned with respect to the optical component housing. More specifically, when the reflection member is not disposed at a proper position corresponding to the designed position, the reflection member cannot reflect the entering light toward an appropriate position. In this case, the efficiency of using the light emitted from the light source may be lowered, or the formed image light may be deteriorated. For overcoming this problem, such a structure is known which includes a posture control lever disposed on the back side of a reflection mirror (the side opposite to the light entering side) as the reflection member to control the position of the reflection mirror by operating the lever (for example, see JP-A-2005-202148).

The reflection mirror included in the structure shown in JP-A-2005-202148 is attached to a reflection mirror attachment unit provided on a component receiving member constituting an optical component housing in such a condition as to be urged toward the attachment unit by an urging member. An opening which is formed on the component receiving member and through which optical components are inserted is closed by a cover member which similarly constitutes the optical component housing. In this structure, the position of the reflection mirror is controlled by operating the lever projecting through an opening of the cover member.

According to the projector disclosed in JP-A-2005-202148, the lever projects to the outside of the optical component housing. In this case, the optical component housing containing the reflection mirror becomes large. Particularly when a control board disposed inside the projector to control the overall operation of the projector is provided in such a manner as to cover the optical device having the optical component housing, the increase in the size of the optical device has a significant effect on the overall size of the projector. Thus, an optical device having a reduced size has been demanded.

SUMMARY

It is an advantage of some aspects of the invention to provide an optical device and a projector capable of achieving size reduction.

An optical device according to an aspect of the invention includes a housing, and a reflection member disposed at a predetermined position within the housing. The housing includes: a receiving opening through which the reflection member is inserted to be accommodated in the housing; and an attachment unit to which the reflection member is attached. The reflection member includes: a front portion which has a reflection area for reflecting supplied light; a back portion positioned on the side opposite to the front portion; and a fixing unit positioned within the surface of the back portion and fixed to the attachment unit. The fixing unit has an opening into which a position control jig inserted in an attachment direction of attaching the reflection member to the attachment unit through the receiving opening is inserted.

According to this structure, the fixing unit of the reflection member fixed to the attachment unit provided in the housing is positioned within the surface of the back portion. In this case, no part of the reflection member projects to the outside of the reflection member viewed from the light entering side. Thus, when the reflection member is attached to the housing, such a component as the lever included in the structure shown in JP-A-2005-202148 does not protrude to the outside of the housing. Accordingly, the optical device can be made compact.

Moreover, the fixing unit has the opening into which the jig is inserted in the attachment direction of attaching the reflection member to the attachment unit through the receiving opening. In this case, the jig can easily engage with the reflection member. Accordingly, the reflection member and the jig can easily engage with each other and disengage from each other, thereby facilitating the position control of the reflection member.

It is preferable that the fixing unit includes a substantially cylindrical pin extending in the attachment direction, and a contact portion contacting the attachment unit. In this case, the attachment unit includes a hole through which the pin is inserted, and a support portion which contacts the contact portion and supports the fixing unit.

According to this structure, the position of the reflection member is controlled by rotating the reflection member around the center axis of the pin inserted through the hole. At the time of the position control, the fixing unit and thus the reflection member are supported by the support portion. In this case, the jig for controlling the position of the reflection member is not required to hold the reflection member. Thus, the position of the reflection member can be easily controlled, and the structure of the jig can be simplified.

It is preferable that one of parts of the contact portion and the support portion opposed to each other has a curved surface centered on a line extending in a direction of inserting the pin through the hole and expanding toward the other part. In this case, the other of the parts of the contact portion and the support portion opposed to each other has a flat surface substantially orthogonal to the attachment direction. Also, a predetermined clearance allowing rotation of the reflection member with the fulcrum of the rotation of the reflection member located at the contacting area between the curved surface and the flat surface is provided between the edge of the hole and the pin inserted through the hole.

According to this structure, one of the contact portion and the support portion has the curved surface, and the other has the flat surface. In this case, the position of the reflection member can be controlled by inclining the reflection member in the direction in which the one portion follows the other portion (the rotation direction around the center axis orthogonal to the center axis of the pin as the guiding direction) with the fulcrum located at the contacting area between the contact portion and the support portion. Since the predetermined clearance is provided between the pin and the edge of the hole, the position control of the reflection member is not interrupted. Thus, the position control direction of the reflection member can be further varied such that the reflection member can be disposed at a more appropriate position.

It is preferable that the contact portion is formed at the base end of the pin. In this case, the cross point of the center axis of the pin and the center axis of the reflection member inclined with the fulcrum of the inclination of the reflection member located at the contacting area is positioned almost on an extension line from the optical axis of the light supplied to the reflection member when the reflection member is accommodated in the housing.

According to this structure, the displacements at both ends of an area for receiving light (light receiving area) on the front portion can be made substantially equal at the time of the position control of the reflection member.

More specifically, at the time of rotation of the reflection member around the center axis of the pin, the displacements at both the ends of the light receiving area in the direction orthogonal to the center axis of the pin can be made substantially equal under the condition in which a point on the center axis of the pin is positioned on the extension line from the optical axis of the supplied light.

Also, at the time of inclination of the reflection member with the fulcrum of the inclination located at the contacting area between the contact portion and the support portion, the displacements at both the ends of the light receiving area in the direction orthogonal to the center axis of the inclination of the reflection member, that is, the displacements at both the ends in the direction of the center axis of the pin can be made substantially equal under the condition in which the center axis of the inclination of the reflection member is positioned on the extension line from the optical axis of the supplied light.

Thus, the displacements at both the ends of the light receiving area can be made substantially equal at the time of the position control of the reflection member. Accordingly, the position of the reflection member can be adequately controlled.

It is preferable that the fixing unit contains a pair of contact surfaces each of which forms the edge of the opening and contacts the jig. In this case, at least one of the pair of the contact surfaces is an inclined surface approaching the other surface in the insertion direction of the jig.

According to this structure, the jig contacts the pair of the contact surfaces forming the edge of the opening. In this case, at least one of the pair of the contact surfaces is an inclined surface approaching the other surface in the insertion direction of the jig. Thus, the jig inserted into the opening and the contact surfaces can securely engage with each other. Moreover, the jig can easily give a load to the fixing unit in the insertion direction of the jig (i.e., the attachment direction of the reflection member to the attachment unit) for preventing swing of the fixing unit in the attachment unit. Furthermore, the jig can be easily removed from the opening after the position control of the reflection member. Accordingly, the position control of the reflection member can be further easily performed.

A projector according to another aspect of the invention includes the optical device described above.

According to this structure, advantages similar to those of the optical device can be offered, and size reduction of the projector can be achieved.

DESCRIPTION OF EXEMPLARY EMBODIMENT

An embodiment of the invention is hereinafter described with reference to the drawings.

Structure of Projector

FIG. 1is a perspective view of a projector according to this embodiment as viewed from the front.

The projector1in this embodiment forms image light corresponding to image information received from an external device or the like, and projects the image light on a projection surface such as a screen. As illustrated inFIG. 1, the projector1includes an external housing2and a device main body3accommodated in the external housing2.

The external housing2is a case member made of synthetic resin and having a substantially parallelepiped shape as a whole. The external housing2has an upper case (not shown) forming the upper part, a lower case22forming the lower part, and a front case (not shown) forming the front part (the part on the side where the image light is projected from a projection unit45described later).

Structure of Device Main Body

The device main body3as a unit for processing the image information and forming and projecting image light corresponding to the image information is fixed to the lower case22. The device main body3has an optical device4, a power source device5, a cooling device6, and a control device (not shown).

The power source device5is disposed on the front part side of the projector1. The power source device5converts commercial alternating current inputted from the outside into direct current, and supplies the direct current to the respective electronic components included in the projector1by boosting and reducing voltage.

The cooling device6has a plurality of fans (such as fans62and63) and a plurality of ducts (such as a duct61). The cooling device6introduces outside air through an intake port (not shown) formed on the external housing2by using the fans rotating under the control of the control device, and cools the optical device4, the power source device5, the control device and the like by using the introduced air. The cooling device6discharges the air having cooled the respective devices to the outside through a discharge port221formed on the lower case22.

The control device controls the operation of the projector1. For example, the control device performs processes corresponding to input operations inputted through keys (not shown) provided on the external housing2, and processes inputted image information to output drive signals corresponding to the image information to the optical device4. Though not shown in detail, the control device is a circuit board on which CPU (central processing unit) and the like are mounted, and is disposed above the optical device4.

Structure of Optical Device

FIG. 2schematically illustrates the structure of the optical device4.

The optical device4forms image light corresponding to the drive signals inputted from the control device, and projects the image light on the projection surface. The optical device4has a substantially L shape in the plan view extending along the back surface of the external housing2and extending along the side surface of the external housing2.

As illustrated inFIG. 2, the optical device4has an illumination optical unit41, a color separation optical unit42, a relay optical unit43, an electro-optic unit44, the projection optical unit45, and an optical component housing46for accommodating and positioning the respective optical units41through45on an illumination optical axis A set inside the optical component housing46.

The illumination optical unit41has a light source411, lens arrays412and413, a polarization conversion element414, and a superimposing lens415.

The light source411has a discharge-type light source lamp416constituted by an extra-high pressure mercury lamp or the like, a reflector417for reflecting light emitted from the light source lamp416and converging the light at a predetermined position, and a collimating concave lens418for collimating light converged by the reflector417with respect to the illumination optical axis A. It is possible to employ a solid light source such as LED (light emitting diode) in place of the light source lamp416.

Each of the lens arrays412and413has small lenses disposed in matrix at positions corresponding to those of the other lens array. The lens array412divides light emitted from the light source411into a plurality of partial lights and forms images of the lights in the vicinity of the lens array413. The lens array413forms the images released from the respective small lenses of the lens array412on image forming areas of liquid crystal panels441described later in cooperation with the superimposing lens415disposed downstream on the optical path.

The polarization conversion element414converts the respective partial lights received from the lens array413into one type of linear polarized lights.

The color separation optical unit42has two dichroic mirrors421and422and a reflection member423as a unit for separating the plural partial lights emitted from the illumination optical unit41into three color lights in red (R), green (G), and blue (B). The green light and blue light of these color lights enter entrance side polarization plates442for green and blue lights via converging lenses419, and the red light enters the entrance side polarization plate442for red light via the relay optical unit43and the converging lens419. The structure of the reflection member423and the attachment of the reflection member423to the optical component housing46will be described in detail later.

The relay optical unit43as a unit for allowing the red light whose optical path is longer than those of the other color lights to be used without decrease in the use efficiency supplies the red light to the entrance side polarization plate442for red light. The relay optical unit43has an entrance lens431, relay lenses433, and reflection mirrors432and434. While the red light passes the relay optical unit43in this embodiment, the other color lights such as the blue light may pass the relay optical unit43.

The electro-optic unit44modulates entering light and forms image light. The electro-optic unit44has the three liquid crystal panels441as light modulation units (liquid crystal panel for red light441R, liquid crystal panel for green light441G, and liquid crystal panel for blue light441B), the three entrance side polarization plates442each of which is disposed on the light entrance side of the corresponding liquid crystal panel441, three exit side polarization plates443each of which is disposed on the light exit side of the corresponding liquid crystal panel441, and a cross dichroic prism (hereinafter abbreviated as “prism” in some cases)444as a color combining unit. The electro-optic unit44is a unit including these components as one body.

The respective entrance side polarization plates442transmit only polarized lights having the same polarization direction as the polarization direction equalized by the polarization conversion element414among respective color lights separated by the color separation optical unit42, and absorb the other lights.

Each of the liquid crystal panels441has a pair of transparent glass substrates between which liquid crystals as electro-optic substances are sealed, and modulates the polarization direction of the polarized lights released from the entrance side polarization plates442by controlling the orientation condition of the liquid crystals according to the drive signals inputted from the control device.

The respective exit side polarization plates443transmit polarized lights having a certain direction (such as lights having a polarization axis orthogonal to the light transmission axis of the entrance side polarization plates442) of the lights released from the liquid crystal panels441, and absorb the other lights.

The prism444forms a color image by combining the lights released from the respective exit side polarization plates443. The prism444has a substantially square shape in the plan view produced by affixing four rectangular prisms. Two dielectric multilayer films are provided on the interfaces between the rectangular prisms affixed to each other. These dielectric multilayer films transmit the color light released from the liquid crystal panel441G and received via the exit side polarization plate443, and reflects the color lights released from the liquid crystal panels441R and441B and received via the exit side polarization plates443. By this method, image light as a combination of the red light, green light, and blue light can be formed.

The projection optical unit45expands and projects the image light formed by the electro-optic unit44. The projection optical unit45includes a combination lens having a plurality of lenses (such as a Fresnel lens451disposed at the leading end in the projection direction) and a lens barrel452containing the plural lenses.

The optical component housing46is a box-shaped component made of synthetic resin and containing the illumination optical axis A as a designed optical axis on which the respective optical units41through45are disposed at predetermined positions. As illustrated inFIG. 1, the optical component housing46has a receiving opening4711through which the respective optical units41through43are inserted, and further has a component receiving member47having a plurality of grooves (not shown) for positioning the respective optical units41through43, a cover member for closing the receiving opening4711, and a head49to which the electro-optic unit44and the projection optical unit45are attached.

The component receiving member47corresponds to a housing according to the invention. The component receiving member47has the receiving opening4711opening upward, and further has a main section471having a substantially concave vertical cross section and containing the respective optical units41through43except for the light source411, and a light source receiving section472for accommodating the light source411.

The light source receiving section472has a side wall4721which surrounds the light source411accommodated in the light source receiving section472, and an opening4722which has an edge formed by the side wall4721and opens upward. Thus, the light source411can be inserted into and removed from the light source receiving section472in the vertical direction.

Structure of Attachment Unit

FIG. 3is a perspective view illustrating a part of the main section471, and more particularly a perspective view of an attachment unit7provided on the main section471.

The main section471has the attachment unit7to which the reflection member423is attached. As illustrated inFIG. 3, the attachment unit7has a substantially L-shaped vertical cross section concaved toward the inside of a side wall4712forming the edge of the receiving opening4711. The attachment unit7has a pair of side portions71opposed to each other, a front portion72connecting the ends of the pair of the side portions71and extending in the vertical direction (the direction substantially parallel with the side wall4712rising from a bottom4713of the main section471), a support portion73extending substantially in parallel with the bottom4713, and a pair of guide portions74rising from the support portion73to be opposed to the corresponding side portions71.

The upper surface of the support portion73(the surface in the opening direction of the receiving opening4711) has a flat surface formed as a flat portion, and has a hole731substantially at the center of the support portion73. A pin814of a fixing unit8(described later) provided on the reflection member423is inserted through the hole731.

The reflection member423is attached to the attachment unit7having this structure in the direction orthogonal to the opening surface of the receiving opening4711from above. Thus, the attachment direction of the reflection member423to the attachment unit7is the vertical direction when the main section471is mounted on a horizontal surface. The attachment and position control of the reflection member423with respect to the attachment unit7will be described in detail later.

Structure of Reflection Member

FIG. 4is a view illustrating the reflection member423as viewed from the above, below, side and rear (back) of the reflection member423.FIGS. 5 and 6are perspective views of the reflection member423as viewed from above and below.

As described above, the reflection member423is a mirror which reflects the blue light divided by the dichroic mirror421and guides the blue light to the converging lens419for blue light. As illustrated inFIGS. 4 through 6, the reflection member423has a substantially rectangular front portion4231which has a reflection area for reflecting the entering blue light on almost the entire surface of the front portion4231, and a back portion4232forming the opposite side of the front portion4231. The fixing unit8fixed to the attachment unit7is attached to the back portion4232by an adhesive or the like.

Structure of Fixing Unit

The fixing unit8is provided within the surface of the back portion4232. Thus, the fixing unit8does not project to the outside of the reflection member423when the reflection member423is viewed from the front or the back. The fixing unit8thus designed has a main portion81, a pair of extending portions82extending from the left and right ends of the main portion81along the back portion4232, and a pair of engaging portions83extending from the projection ends of the extending portions82and bended substantially at right angles in directions away from the back portion4232.

The main portion81has a substantially parallelepiped shape as a whole, and includes a rectangular opening811opening upward, and a pair of contact surfaces812and813forming the longer sides of the edge of the opening811and disposed opposed to each other.

The pair of the contact surfaces812and813are formed in such a manner as to extend along the back portion4232. A jig J for adjusting the position of the reflection member423(seeFIG. 7) contacts the pair of the contact surfaces812and813. The pair of the contact surfaces812and813are provided as slopes inclined in such a manner as to come close to each other toward the tip of the opening811in its depth direction (the insertion direction of the jig J described later). A curved portion8121(seeFIGS. 8 and 9) having a shape corresponding to the shape of the jig J (more specifically, an end portion J221described later) is formed at the tip of the contact surface812in the depth direction on the back portion4232side.

A substantially cylindrical pin814extending downward is provided at the lower end of the main portion81. The pin814is inserted through the hole731formed on the attachment unit7when the fixing unit8is fixed to the attachment unit7.

A contact portion815contacting the support portion73when the pin814is inserted through the hole731is further provided on the base side of the pin814in its extending direction. The contact portion815has a curved surface expanding downward. The guiding direction of the reflection member423is positioned by inclination of the contact portion815having the curved surface along the support portion73with the pin814inserted through the hole731. Thus, the outside diameter of the pin814including a clearance necessary for the position control (a clearance allowing inclination of the pin814) is made smaller than the inside diameter of the hole731.

The cross point of the center axis of the pin814and the center axis of the inclined contact portion815is determined in such a position as to be located substantially on a line extended from the optical axis of the light supplied to the reflection member423(the blue light), which will be described in detail later.

As described above, the pair of the extending portions82extend from the left and right ends of the main portion81and are fixed to the back portion4232by an adhesive or the like together with the main portion81.

Each of the pair of the engaging portions83is inserted into a gap G between the side portion71and the guide portion74close to each other (seeFIG. 3) when the fixing unit8is fixed to the attachment unit7. After the position control of the reflection member423, adhesives are injected into the gaps G such that the fixing unit8and thus the reflection member423are fixed to the attachment unit7.

Structure of Jig

FIG. 7is a perspective view illustrating the attachment unit7, the reflection member423, and the jig J.FIG. 8is a vertical cross-sectional view of these units, andFIG. 9is a vertical cross-sectional view illustrating a combined condition of the units.

As described above, the jig J engages with the fixing unit8of the reflection member423attached to the attachment unit7to control the position of the reflection member423with respect to the entering light (the blue light). As illustrated inFIGS. 7 through 9, the jig J has a shaft portion J1fixed to a moving device (not shown) for moving the jig J, and an engaging portion J2provided at the tip of the shaft portion J1.

The engaging portion J2has a substantially L shape in the side view having a size larger than the outside diameter of the shaft portion J1. The engaging portion J2has a substantially parallelepiped base portion J21crossing the center axis of the shaft portion J1at right angles, and a wide projecting portion J22extending from the lower end of the base portion J21.

The projecting portion J22is inserted into the opening811formed on the main portion81of the fixing unit8to contact the contact surfaces812and813forming the edge of the opening811. A tip J221of the projecting portion J22has a circular-arc shape corresponding to the shape of the curved portion8121such that the tip J221can contact the curved portion8121. Thus, the load of the jig J in its insertion direction into the opening811is easily transmitted to the fixing unit8.

Position Control of Reflection Member

FIG. 10is a plan view showing the combined condition of the reflection member423, the attachment unit7, and the jig J.

The position control of the reflection member423is now discussed.

As illustrated inFIGS. 9 and 10, the reflection member423is attached to the attachment unit7such that the pair of the engaging portions83of the fixing unit8provided on the reflection member423can be inserted into the gaps G and that the main portion81can be positioned between the pair of the guide portions74. In this case, the fixing unit8and thus the reflection member423become self-supported at the attachment unit7by insertion of the pin814provided on the main portion81through the hole731formed on the support portion73and by contact between the contact portion815and the support portion73.

When the projecting portion J22of the jig J is inserted into the opening811in this condition, the projecting portion J22contacts the pair of the contact surfaces812and813. In this case, the tip J221of the projecting portion J22contacts these surfaces along the curved portion8121formed on the contact surface812. Under this condition, the extension line from the center axis of the shaft portion J1agrees with the extension line from the center axis of the pin814. That is, the center axis of the pin814is positioned on a line extending in the insertion direction of the jig J.

In this condition, the distance between the reflection member423and the side wall4712is controlled by advancing and withdrawing the shaft portion J1of the jig J in a T1direction (the direction in which the reflection member423moves away from the side wall4712) and a T2direction (the direction in which the reflection member423approaches the side wall4712). By this method, the position of the reflection member423in the direction along the optical axis of the entering light is controlled.

When the shaft portion J1is rotated in an S1direction (the anticlockwise direction as viewed from above) and an S2direction (the clockwise direction as viewed from above) around the center axis of the shaft portion J1under the above condition, the fixing unit8rotates in the same directions as the S1and S2directions accordingly. As a result, the reflection member423rotates in the same direction as the rotation direction of the fixing unit8, thereby controlling the left and right inclinations of the reflection member423with respect to the optical axis of the entering lights.

On the other hand, when the shaft portion J1is inclined under the above condition, the contact portion815swings along the support portion73. More specifically, when the end of the shaft portion J1on the side opposite to the engaging portion J2side is inclined in the front-rear direction (the T1direction and the T2direction), the fixing unit8engaging with the projecting portion J22rotates frontward and rearward around a center axis of a line extending parallel with a direction orthogonal to the inclination direction of the shaft portion J1and the center axis of the pin814and passing the contact area between the support portion73and the contact portion815. As a result, the reflection member423rotates in the same direction as the rotation direction of the fixing unit8, thereby controlling the inclination in the vertical direction (inclination of the guiding direction) of the reflection member423with respect to the optical axis of the entering light.

FIG. 11illustrates the positional relationship between the rotation center of the reflection member423under the position control and the optical axis of the light supplied to the reflection member423.FIG. 11shows the reflection member423as viewed from the front (light entering side). InFIG. 11, a light receiving area AR of the reflection member423is indicated by a dashed line.

As illustrated inFIG. 11, a rotation center C of the reflection member423under the position control, that is, the rotation center C as the cross point of the center axis of the pin814as the rotation axis of the shaft portion J1rotated clockwise and anticlockwise and the center axis of the inclined shaft portion J1is positioned on an extension line from the optical axis of the light supplied to the front portion4231. In other words, the rotation center C of the reflection member423passes the center of the light receiving area AR and lies on the extension line from the optical axis of the light.

According to this structure, at the time of the position control of the reflection member423by rotating the shaft portion J1clockwise and anticlockwise, the displacements at the left and right ends of the light receiving area AR (i.e., both the ends in the direction orthogonal to the center axis of the pin814when the reflection member423is viewed from the light entering side) can be made substantially equal.

Similarly, at the time of the position control of the reflection member423by inclining the shaft portion31frontward and rearward (toward the base end and the leading end in the light entering direction with respect to the reflection member423), the displacements at the upper and lower ends of the light receiving area AR (i.e., both the ends on the line extended from the center axis of the pin814) can be made substantially equal.

The reflection member423positioned in this manner is fixed to the attachment unit7by the adhesives injected into the gaps G and hardened. Thus, the base portion321of the jig J is made smaller than the main portion81when the fixing unit8is viewed in the plan view so as not to prevent injection of the adhesives as illustrated inFIG. 10.

According to the projector1in this embodiment, the following advantages can be offered.

As illustrated inFIG. 4, the fixing unit8is positioned within the surface of the back portion4232. In this case, no part projects to the outside of the reflection member423when the reflection member423is viewed from the front (light entering side). That is, the reflection member423attached to the component receiving member47does not project to the outside of the receiving opening4711of the component receiving member47(more specifically, the main section471). Thus, the optical device4can be made compact.

The fixing unit8has the opening811into which the projecting portion J22of the jig J is inserted in the attachment direction of the reflection member423to the attachment unit7. In this structure, the projecting portion J22can be easily inserted and removed into and from the fixing unit8. Thus, the reflection member423and the jig J can easily engage with each other and disengage from each other, thereby facilitating the position control of the reflection member423.

The position of the reflection member423can be controlled by rotating the jig J around the center axis of the pin814which extends in the insertion direction of the jig J into the opening811and is inserted through the hole731. Since the reflection member423is supported by the support portion73via the fixing unit8within the attachment unit7, the jig J is not required to hold the reflection member423. Thus, the position of the reflection member423can be easily controlled, and the structure of the jig J can be simplified. Furthermore, the necessity for separately providing a member for positioning the fixing unit8within the attachment unit7is eliminated, which does not increase the number of the required components.

The contact portion815has the curved surface whose central portion expands toward the support portion73, and the support portion73has a flat surface brought into contact with the curved surface. According to this structure, the position of the reflection member423can be controlled by inclining the reflection member423in the direction in which the curved surface follows the flat surface (the rotation direction around the center axis orthogonal to the center axis of the pin814as the guiding direction) with the fulcrum located at the contacting area between the curved surface and the flat surface. Since the clearance necessary for the position control is provided between the pin814and the edge of the hole731, the position control of the reflection member423is not interrupted. Thus, the position control direction of the reflection member423can be further varied such that the reflection member423can be disposed at a more appropriate position.

The rotation center C of the reflection member423rotated by the jig J is located substantially on the extension line from the optical axis of the light supplied to the reflection member423. According to this structure, the displacements at both the ends (the left and right ends and the upper and lower ends) of the light receiving area AR can be made substantially equal as explained above. Thus, the position of the reflection member423can be further adequately controlled. In addition, the entering blue light can be securely supplied to the image forming area of the liquid crystal panel441B via the converging lens419and the entrance side polarization plate442by using the reflection member423under the position control in this manner. Thus, the efficiency of using the blue light can be improved.

The pair of the contact surfaces812and813forming the edge of the opening811and contacting the projecting portion J22of the jig J are inclined surfaces inclined in the direction of approaching each other toward the end in the insertion direction of the projecting portion J22. According to this structure, the engagement between the projecting portion J22and the contact surfaces812and813can be secured. Moreover, at the time of the position control of the reflection member423, the load for preventing the swing of the reflection member423self-supported on the support portion73in the insertion direction of the jig J (i.e., the attachment direction of the reflection member423to the main section471) can be easily given to the fixing unit8and thus the reflection member423. Furthermore, the projecting portion J22can be easily removed from the opening811after the position control of the reflection member423. Thus, the position control of the reflection member423can be further easily performed.

Modification of Embodiment

The invention is not limited to the embodiment described and depicted herein. It is therefore intended that modifications, improvements and the like of the embodiment without departing from the scope and spirit of the invention are included in the invention.

According to this embodiment, the hole731through which the pin814is inserted is formed on the support portion73for supporting the contact portion815provided at the base end of the pin814. However, the contact portion may be disposed not at the base end of the pin814but at the lower parts of the extending portions82, and the support portion may be provided at a position corresponding to the contact portion, for example.

According to this embodiment, the surface of the contact portion815opposed to the support portion73is a curved surface, and the surface of the support portion73opposed to the contact portion815is a flat surface. However, the surface of the support portion73opposed to the contact portion815may be a curved surface, and the surface of the contact portion815opposed to the support portion73may be a flat surface.

According to this embodiment, the pin814has a substantially cylindrical shape. However, when the position control of the reflection member by rotation around the center axis of the pin is unnecessary, the pin may have a prismatic shape. In this case, the hole into which the pin is inserted is formed in a shape corresponding to the shape of the pin. In case of the prismatic pin, the position control of the reflection member can be performed by rotation around the center axis of the pin as the rotation axis when the inside diameter of the hole731is sufficiently larger than the outside diameter of the pin.

According to this embodiment, the pair of the contact surfaces812and813engaging with the projecting portion J22of the jig J are inclined surfaces approaching each other toward the end in the insertion direction of the projecting portion J22. However, only one of the pair of the contact surfaces may be an inclined surface approaching the other surface toward the end in the insertion direction of the projecting portion J22. The pair of the contact surfaces are not required to be inclined but may be substantially parallel surfaces extending in the insertion direction of the projecting portion J22. That is, the shapes of the contact surfaces may be any shapes as long as the projecting portion J22can engage with the inside of the opening811.

According to this embodiment, the projector1has the three liquid crystal panels441. However, the invention is applicable to a projector including two or a smaller number of liquid crystal panels, or four or a larger number of liquid crystal panels.

While the optical device4has a substantially L shape in the plan view in this embodiment, the optical device4may have other shapes. For example, an optical device having a substantially U shape in the plan view may be employed.

While the transmission type liquid crystal panels441each of which has the separate light entrance surface and light exit surface are used in this embodiment, reflection type liquid crystal panels each of which has one surface functioning as both the light entrance surface and the light exit surface may be used.

According to this embodiment, the projector1having the liquid crystal panels441as the light modulation devices has been discussed. However, light modulation devices having different structure may be employed as long as they can modulate entering light according to image information to form optical images. For example, the invention is applicable to a projector including light modulation devices other than liquid crystal devices such as devices using micromirrors. When these light modulation devices are used, the light entrance side and light exit side polarization plates442and443can be eliminated.

While the projector1including the optical device according to the invention has been discussed, the invention is applicable to an optical device included in an image capture device such as a camera, or an illumination device.

The invention can be applied to an optical device, and particularly to an optical device included in a projector as a preferable application.