JP2011059459A - Image projection device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projection device equipped with a holding structure reduced in deviation of positional relation between a projection image and a reflection surface even when performing the tilt adjustment of a reflection type optical element. <P>SOLUTION: The image projection device has the holding structure for holding and fixing the reflection type optical element 6 so that an angle is adjustable. The reflection type optical element has guide shafts 11 and 12 having an axial center in a first direction orthogonal to a center optical axis of a projection image screen and parallel with one side of the projection image screen on an outer periphery part, the guide shafts rotatably held in groove parts 21 and 22 provided in a first holding member 20. The first holding member 20 has guide shafts 24 and 25 provided in a second direction orthogonal to the first direction and having an axial center orthogonal to the center optical axis of the projection image screen on an outer periphery part, the guide shafts rotatably held in groove parts 31 and 32 provided in a second holding member 30. The axial centers of the guide shafts of the reflection type optical element and the guide shafts of the first holding member are made to come into contact with a point where the reflection surface of the reflection type optical element and the center optical axis of the projection image screen cross each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image projection apparatus that projects a video such as a still image or a moving image on a projection surface, and an image display apparatus including the image projection apparatus.

  Image projection generated by an image generation unit having a light source and an image forming element, and projected and projected on a projection surface such as a screen by reflection of a reflective optical element, by passing through a projection optical system such as a projection lens The device is known, and is applied to a rear projection type or front projection type image display device.

In such an image projection apparatus, the position and inclination of the reflective optical element with respect to the image generation unit and the projection lens connected to the image generation unit greatly affect the quality of the image.
In addition, many adjustments have been made to the apparatus because of the large number of related optical members and the fact that the image projection apparatus is a video enlargement apparatus.
For this reason, in an image projection apparatus using a reflective optical element, many adjustments have been made to the reflective optical element, and various proposals have been made.

  However, the adjustment of the conventional reflection type optical element tends to change the adjustment performed in one direction when the adjustment is performed in one direction, which requires a lot of adjustment time and performs the optimal adjustment. There was a drawback that it was difficult.

For example, Patent Document 1 (Japanese Patent Laid-Open No. 2008-139442) discloses a reflection optical element (mirror) mounting structure and an adjustment method. However, the mirror rotation axis is separated from the mirror reflection surface, which is optimal. It is difficult to make adjustments.
That is, if the mirror rotation axis is separated from the mirror reflection surface, the position where the image light is reflected by the mirror changes due to the rotation adjustment around the axis. Further, as described in this prior art, it can be used as an adjustment only when the reflection surface of the mirror is a rotation surface around the rotation axis. This makes it impossible to design a reflecting surface with an aspherical mirror surface, which is a major limitation on optical design.

  Patent Document 2 (Japanese Patent Laid-Open No. 2006-18083) and Patent Document 3 (Japanese Patent Laid-Open No. 2007-65053) disclose support structures for reflective optical elements (aspherical mirrors, resin mirrors, etc.). The conventional techniques described in Patent Documents 2 and 3 are for absorbing distortion caused by expansion of the mirror surface due to temperature change or the like, and do not perform rotation adjustment around the axis.

Patent Document 4 (Patent No. 3913265) discloses a support mechanism and an adjustment method for a reflector, and the reflection optical axis of the reflector is used as an adjustment point. The adjustment center is not the mirror center.
In addition, the definition of the reflecting surface is constrained by a spherical surface with the optical axis as a target. Further, the mirror surface shape is restricted such that the mirror center is removed from the reflection surface or the mirror surface is the optical axis rotation center.

  Patent Document 5 (Japanese Patent Laid-Open No. 2007-41544) discloses a holding structure for a reflective optical element, which is for absorbing distortion caused by expansion of a mirror surface due to a temperature change or the like. It does not adjust the rotation around the shaft.

The present invention provides a reflective optical element holding structure in an image projection apparatus, in which a reference reflection point does not move even when adjusting a plurality of directions of the reflective optical element, and the adjustment of each direction is independent. The task is to adjust the items. That is, in the present invention, the position of the mirror reflection point at the center of the projection screen does not change even if adjustment is performed by rotation around the axis, and only the inclination of the mirror surface about the axis is adjusted. It is an object of the present invention to make it possible to perform adjustment independent of the accuracy of components for matching the center position of the projection screen and the position of the reflection mirror.
In addition, problems such as distortion and blurring of the image due to thermal changes of the mirror surface, which are likely to occur due to differences in the material (difference in thermal expansion) between parts created by molding, such as reflective optical elements, and structural parts, such as holding members. Mitigation is also an issue.

  Furthermore, the present invention relates to a tilt adjustment structure for a reflective optical element and a holding structure for a reflective optical element, which are required in an image projection apparatus using the reflective optical element. The reflection type optical element of this image projection device is created by the image generation unit and reflects and projects the image light from the projection optical system that processes it onto the projection surface. Many have a surface. For this reason, naturally, the relationship between the projection light and the reflecting surface needs to match the exact position and inclination.

  Here, it is necessary to make adjustments in many items regarding the attachment of the reflective optical element, and as described above, many adjustment methods have been proposed in the past, but the simplicity of the mechanism and method, and the cost problem. However, much attention was not paid to the interrelationships between coordination activities and secondary effects on other coordination factors.

  The present invention provides a means for solving the above-described problems. Specifically, the present invention relates to tilt adjustment of a reflective optical element. Even if tilt adjustment is performed, the positional relationship between a projected image and a reflecting surface is not shifted. Provided is an image projection apparatus having an adjustment / holding structure that minimizes deviation of the reflection surface due to temperature or the like, distortion, and the like, and a projection-type image display apparatus including the image projection apparatus The purpose is that.

In order to achieve the above object, the present invention employs the following solutions.
According to a first aspect of the present invention, there is provided an image generation unit that generates video light, a projection optical system that projects the video light generated by the image generation unit, and a projection optical system that reflects the projection video from the projection optical system. In the image projection apparatus having a reflection optical system that reflects toward the projection surface by an element, the reflection optical system holds and fixes the reflection type optical element by a first holding member and a second holding member so that the angle can be adjusted. The reflective optical element has an axial center in a first direction that is orthogonal to the central optical axis of the projected video screen and parallel to one side of the projected video screen, on the outer periphery outside the reflecting surface. Having a guide shaft, the guide shaft being held in a groove provided in the first holding member, and having a degree of freedom of rotation with respect to the first holding member around the shaft in the first direction; The first holding member holds the reflective optical element, and A guide shaft provided in a second direction perpendicular to the first direction and having an axis that is perpendicular to a central optical axis of the projection video screen; It is held in a groove provided in the holding member and has a degree of freedom of rotation with respect to the second holding member around the axis in the second direction, and the guide shaft of the reflective optical element and the first The axis of the guide shaft of the one holding member is configured so as to be in contact with or near the point where the reflection surface of the reflective optical element and the central optical axis of the projection video screen intersect. (Claim 1).

  According to a second solving means of the present invention, in the image projection apparatus according to the first solving means, the groove provided in the first holding member has a structure for holding the guide shaft of the reflective optical element, and the guide The shaft is fixed to the reference surface in the groove so as to be parallel to the first direction by a pressing member with a degree of freedom of rotation around the shaft, and is provided on the second holding member. The groove portion has a structure for holding the guide shaft of the first holding member, and the guide shaft has a degree of freedom of rotation around the shaft by a pressing member on a reference surface in the groove provided to be parallel to the second direction. The presser foot is fixed in a shape having a (claim 2).

  According to a third solving means of the present invention, in the image projection apparatus of the first or second solving means, a rib surface parallel to the first direction is provided outside the reflecting surface of the reflective optical element, After adjusting the rotation of the reflective optical element around the guide shaft, by fixing the rib surface to the first holding member, the rotational angle position of the reflective optical element with respect to the first holding member is regulated, and The first holding member is provided with a rib surface parallel to the second direction, and the rib surface is fixed to the second holding member after adjusting the rotation of the first holding member around the guide shaft. Thus, the rotation angle position of the first holding member with respect to the second holding member is regulated (Claim 3).

  According to a fourth solving means of the present invention, in the image projection apparatus according to any one of the first to third solving means, the position of the reflective optical element in the guide axis direction with respect to the first holding member is the reflective type. The reflective optical element and the first holding member are determined by a rib provided in a direction orthogonal to the guide shaft provided on the outer peripheral portion of the optical element and a groove portion fitted to the rib provided on the first holding member. The mounting margin dimension in the first direction is the difference between the linear expansion coefficients of the respective materials, the temperature difference between the upper limit use temperature of the image projection apparatus and the normal temperature, and the first direction of the reflective optical element. Is set to be distributed according to the ratio of the dimension in the first direction from the center of the rib provided on the reflective optical element to the guide shaft portion. It is characterized by Section 4).

  According to a fifth solving means of the present invention, in the image projection apparatus according to any one of the first to fourth solving means, the first holding member and the second holding member are made of the same material, and the first The position of the holding member in the second direction is a structure determined by pressing with a pressing member against a reference surface position provided on the second holding member (Claim 5).

  According to a sixth solving means of the present invention, in the image projection apparatus according to any one of the first to fifth solving means, the reflective optical element is configured such that, after the rotation position is adjusted, the rib portion is attached to the first holding member. It is adhered and fixed to the groove portion of the (claim 6).

  According to a seventh aspect of the present invention, there is provided an image display apparatus comprising: the image projection apparatus according to any one of the first to sixth aspects; and a screen as a projection surface. The image light generated by the image generation unit is enlarged and projected onto the screen by the projection optical system and the reflection optical system (claim 7).

  In the present invention, the tilt adjustment of the reflective optical element of the image projection apparatus is assumed to be rotational adjustment in two directions, and the rotation axis for the adjustment (the guide axis of the reflective optical element and the guide axis of the first holding member) Since the axial center) is arranged so as to be in contact with or near the point (reflection point) where the reflection surface of the reflective optical element and the center optical axis of the projected video image intersect, the adjustment is performed at the center of the projection screen. As a result, the inclination adjustment is performed, and the adjustment accuracy and the adjustment time can be shortened. Therefore, in the present invention, regarding the tilt adjustment of the reflective optical element, even if tilt adjustment is performed, the positional relationship between the light beam and the reflective surface is small, and the reflective surface is not misaligned or distorted due to temperature or the like. It is possible to realize an image projection apparatus having an appropriate adjustment / holding structure and an image display apparatus having the same.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory diagram of a projection type image display apparatus provided with an image projection apparatus showing an embodiment of the present invention, wherein (a) is a schematic configuration diagram of the projection type image display apparatus viewed from the side, and (b) is ( It is the schematic block diagram which looked at the image projection apparatus of the projection type image display apparatus of a) from the vertically upward direction. It is composition explanatory drawing of the projection type image display apparatus provided with the image projection apparatus which shows another embodiment of this invention, (a) is a schematic block diagram which looked at the projection type image display apparatus from the side, (b) is It is the schematic block diagram which looked at the image projection apparatus of the projection type image display apparatus of (a) from the vertically upward direction. It is a figure which shows one Example of this invention, Comprising: It is a disassembled perspective view which shows the structural example of a reflection type optical element and a holding member holding it. It is explanatory drawing of the holding structure of the reflective optical element shown in FIG. 3, (a) is a schematic principal part sectional drawing which shows the attachment part with respect to the 1st holding member of the guide shaft of a reflective optical element, (b) is It is a schematic principal part sectional drawing which shows the attachment part with respect to the 1st holding member of the control rib of a reflective optical element. FIG. 4 is a schematic perspective view of a main part showing the relationship between the mirror surface of the reflective optical element shown in FIG. 3 and the axis of a guide shaft. FIG. 4 is a schematic perspective view of a main part showing a relationship between an axis of a guide shaft of the reflective optical element shown in FIG. 3 and an axis of a first holding member guide shaft. It is a figure which shows the change of the position of a reflective surface in the case of carrying out rotation adjustment of a reflection type optical element, and (a) is the case where the center position of rotation adjustment of a reflection type optical element exists in the position away from the reflection surface. (B) is a figure which shows an example in case the center position of the rotation adjustment of a reflective optical element exists on a reflective surface.

  The present invention uses a reflective image forming element such as a DMD (digital micromirror device) or a transmissive image forming element such as a transmissive liquid crystal element for an image generating unit, and the image generated by the image generating unit is used as the projection optics. The present invention is characterized by a holding structure for a reflective optical element used in an optical system of an image projection apparatus that projects onto a projection surface by the system, and an adjustment structure thereof. The image projection apparatus according to the present invention is provided in a projection image display apparatus such as a rear projection system or a front projection system, and the reflective optical element has a large screen and is thin. This is a necessary component for realizing the image processing, and is an important component particularly for the requirement to shorten the distance between the display screen and the image projection apparatus.

Hereinafter, specific configuration examples of the present invention will be described in detail with reference to the drawings.
First, referring to FIG. 1, a configuration of a projection type image display apparatus including the image projection apparatus according to the present invention will be described.
FIG. 1 is an explanatory diagram of a configuration of a projection type image display apparatus provided with an image projection apparatus according to an embodiment of the present invention. FIG. 1A is a schematic configuration diagram of the projection type image display apparatus viewed from the side. ) Shows a schematic configuration diagram of the image projection apparatus of the projection type image display apparatus of FIG.
The projection type image display apparatus shown in FIG. 1 includes an image projection apparatus 1 and a screen 8 that is a projection surface. The image projection apparatus 1 includes a light source, an image forming element 2, and a light guide prism 3 that are not shown. The image generation unit configured, the projection optical system 4 having the lens units 4a and 4b for projecting the video light generated by the image generation unit, and the projection video light from the projection optical system (lens unit) 4 on the screen 8 And a reflective optical system 5 having a reflective optical element 6 that reflects toward the surface.

In this image projection apparatus 1, the image forming element 2 is installed such that the center thereof does not coincide with the optical axis of the projection optical system 4. The image forming element 1 is installed shifted in a direction substantially perpendicular to the optical axis O1 of the lens portions 4a and 4b of the projection optical system 4 (vertically below in the illustrated example). For this reason, the optical axis O1 of the projection optical system 4 and the optical axis O2 at the center of the projection video screen do not coincide with each other and are configured to intersect.
As described above, in the image projection apparatus 1 of the projection type image display apparatus shown in FIG. 1, the reflection type optical element 6 of the reflection optical system 5 is generated by the image generation unit and passes through the lens units 4 a and 4 b of the projection optical system 4. Since the center optical axis O2 of the projection image screen of the image light incident on the reflecting surface of the lens intersects the optical axis O1 of the lens units 4a and 4b of the projection optical system 4, it is generated by the image generation unit. The projected image light can be enlarged and projected by the lens portions 4a and 4b of the projection optical system 4, and the projected image light can be projected onto a convex reflecting surface (for example, a convex aspherical surface, a quadric surface, or other free-form surface). Thus, the image is reflected on the screen 8 and obliquely incident on the screen 8 so that the image can be efficiently enlarged and projected on the screen 8. For this reason, the installation position of the image projection apparatus 1 and the screen 8 can be close, and a large-screen and thin rear projection type or front projection type image display apparatus can be realized.

Next, the image projection apparatus 1 will be described more specifically. For example, a DMD is used as the image forming element 2, and illumination light from a light source unit (not shown) is applied to the image forming element (DMD) 2 through the light guide prism 3, and is generated by the image forming element (DMD) 1. The image reflected light passes through the light guide prism 3 and passes through the lens units (a plurality of projection lenses) 4a and 4b of the projection optical system 4 which is the image light processing unit, and then is projected by the reflective optical element 6 of the reflection optical system 5. The direction is changed, and the light is obliquely incident on the screen 8 as a projection surface to form an image.
As described above, in the configuration in which the projection direction is changed by the reflective optical element 6 and obliquely incident on the screen 8 that is the projection surface, the distance between the image projector 1 and the screen 8 is shortened or the position on the screen is high. Therefore, the light rays from the lens units 4 a and 4 b of the projection optical system 4 are subjected to a predetermined correction by the reflection surface of the reflective optical element 6. For this reason, the reflective surface of the reflective optical element 6 is, for example, a convex aspherical surface (for example, a surface having a radius of curvature and an aspherical coefficient, a quadric surface, other free-form surface, etc.).
As a matter of course, the shape of the reflecting surface of the reflective optical element 4 requires a high degree of accuracy, and the relationship between the position, inclination and the like with the lens units 4a and 4b of the projection optical system 4 in front of that requires accuracy.

Next, FIG. 2 is a configuration explanatory view of a projection type image display apparatus provided with an image projection apparatus showing another embodiment of the present invention, and (a) is a schematic configuration diagram of the projection type image display apparatus viewed from the side. (B) has shown the schematic block diagram which looked at the image projection apparatus of the projection type image display apparatus of (a) from the vertically upward direction.
The projection type image display apparatus shown in FIG. 2 includes an image projection apparatus 1 and a screen 8 that is a projection surface. The image projection apparatus 1 includes a light source, an image forming element 1, and a light guide prism 3 that are not shown. The image generation unit configured, the projection optical system 4 having the lens units 4a and 4b for projecting the video light generated by the image generation unit, and the projection video light from the projection optical system (lens unit) 4 on the screen 8 And a reflective optical system 5 having two reflective optical elements 6 and 7 that reflect toward the surface.

  In the image display apparatus shown in FIG. 2, two reflective optical elements 6 and 7 are used for the reflective optical system 5 of the image projecting apparatus 1. For example, the reflective optical element 6 has a free-form surface having a concave reflective surface. The reflective optical element 7 is a plane mirror 5. Other configurations are the same as those in FIG.

  In the image display device shown in FIG. 2, for example, a DMD is used as the image forming element 2, and illumination light from a light source unit (not shown) is applied to the image forming element (DMD) 2 through the light guide prism 3. The image reflected light from the image forming element (DMD) 1 passes through the light guide prism 3 and passes through the lens units (a plurality of projection lenses) 4a and 4b of the projection optical system 4 serving as the image light processing unit. The projection direction is changed by the reflection type optical element (free-form surface mirror) 6, and the image is further reflected by the plane mirror 7 and obliquely incident on the screen 8 as the projection surface.

  The configuration example of the image display apparatus provided with the image projection apparatus 1 has been described above. As the image forming element 2 used in the image projection apparatus 1, a reflective image forming element such as a reflective liquid crystal element is used in addition to the DMD. Alternatively, a transmissive image forming element such as a transmissive liquid crystal element may be used.

In the image projection apparatus 1 constituting the image display apparatus as described above, in the present invention, the aspherical surface (for example, a surface having a radius of curvature and an aspherical coefficient, a quadric surface, other free-form surface, etc.) of the reflection optical system 5 is used. This is characterized by the holding structure of the reflective optical element 6 having a mirror surface and its adjustment structure.
Examples of the holding structure and the adjustment structure for the reflective optical element 6 according to the present invention will be described below.

  FIG. 3 is an exploded perspective view showing a configuration example of a reflection type optical element and a holding member for holding it, showing an embodiment of the present invention. FIG. 4 is an explanatory diagram of the reflection optical element holding structure shown in FIG. 3, and FIG. 4A is a schematic cross-sectional view of the main part showing the attachment portion of the guide shaft of the reflection optical element to the first holding member. FIG. 7B is a schematic cross-sectional view of the main part showing the attachment portion of the regulation rib of the reflective optical element to the first holding member.

The reflective optical system 5 of the image projection apparatus 1 shown in FIG. 1 or FIG. 2 holds and fixes the reflective optical element 6 by the first holding member 20 and the second holding member 30 so that the angle can be adjusted, as shown in FIG. It has a holding structure.
The reflective optical element 6 is orthogonal to the central optical axis of the projection video screen (specifically, the central optical axis of the designed projection video screen) and is parallel to one side of the projection video screen on the outer periphery outside the reflective surface. Guide shafts 11 and 12 having an axial center in the first direction (Y direction in FIG. 3) are held by the groove portions 21 and 22 provided in the first holding member 20. The first holding member 20 has a degree of freedom of rotation around the axis in the first direction (Y direction). The first holding member 20 holds the reflective optical element 6 and is provided on the outer periphery of the first holding member 20 in a second direction (Z direction in FIG. 3) perpendicular to the first direction (Y direction). The guide shafts 24 and 25 each have an axis perpendicular to the central optical axis of the projected image screen. The guide shafts are held in the grooves 31 and 32 provided in the second holding member 30 and the second The second holding member 30 has a degree of freedom of rotation around the axis in the direction (Z direction). Furthermore, the axial centers of the guide shafts 11 and 12 of the reflective optical element 6 and the guide shafts 24 and 25 of the first holding member 20 intersect the reflective surface 10 of the reflective optical element 6 and the central optical axis of the projected video image. It is configured so as to be in contact with a point or in the vicinity thereof.

  The groove portions 21 and 22 provided in the first holding member 20 have a structure for holding the guide shafts 11 and 12 of the reflective optical element 6 (for example, the holding structure shown in FIG. 4A). 12 is pressed and fixed by a pressing member (for example, holding springs) 15 and 16 with a degree of freedom of rotation around the shaft on a reference surface in the groove provided so as to be parallel to the first direction (Y direction). Yes. Further, the grooves 31 and 32 provided in the second holding member 30 also have a structure for holding the guide shafts 24 and 25 of the first holding member 20 (not shown, but the same structure as FIG. 4A). The guide shafts 24 and 25 have a degree of freedom of rotation around the shaft by pressing members (for example, holding springs) 34 and 35 on a reference surface in the groove provided so as to be parallel to the second direction (Z direction). The presser foot is fixed in a shape with

  A rib surface (rib surface of the rib 14) parallel to the first direction (Y direction) is provided outside the reflective surface of the reflective optical element 6, and after adjusting the rotation of the reflective optical element 6 around the guide axis, By fixing the rib surface of the rib 14 to the first holding member 20, the rotational angle position of the reflective optical element 6 with respect to the first holding member 20 is regulated. The first holding member 20 is provided with a rib surface (rib surface of the rib 27) parallel to the second direction (Z direction). After adjusting the rotation of the first holding member 20 around the guide shaft, the rib 27 By fixing the rib surface to the holding portion 33 of the second holding member 30, the rotational angle position of the first holding member 20 with respect to the second holding member 30 is regulated.

The position of the reflective optical element 6 in the guide axis direction with respect to the first holding member 20 is a rib 14 provided in a direction orthogonal to the guide shafts 11 and 12 provided on the outer peripheral portion of the reflective optical element 6, and the rib 14. The margin of attachment in the first direction (Y direction) between the reflective optical element 6 and the first holding member 20 is determined by the groove provided in the first holding member 20 to be fitted, and “the linear expansion coefficient of each material” The difference between “the difference between the upper limit use temperature of the image projection apparatus and the room temperature” and “the width in the first direction of the reflective optical element” is multiplied by the reflection optical. It is set to be distributed according to a ratio of dimensions in the first direction from the center of the rib 14 provided in the element 6 to the guide shaft portions 11 and 12.
Further, the first holding member 20 and the second holding member 30 are made of the same material, and the position of the first holding member 20 in the second direction (Z direction) is the groove 32 provided in the second holding member 30. The structure is determined by pressing the reference surface position with a pressing member (for example, a holding spring) 36.

Next, the holding structure of the present embodiment will be described in more detail.
In the example shown in FIG. 3, the reflective optical element 6 is composed of, for example, a mirror having a free curved surface (free curved surface mirror) on the reflective surface 10, and has high surface accuracy by resin molding using, for example, a resin material such as polycarbonate and a mold. Is formed.
The first holding member 20 that holds the reflective optical element 6 and the second holding member 30 that holds the first holding member 20 are also formed by resin molding using a resin material and a mold. The material of the resin material of the holding member 20 and the second holding member 30 is the same material.

  The reflective optical element 6 has guide shafts 11 and 12 provided so as to protrude in a first direction (Y direction in FIG. 3) outside the reflection surface, and the guide shafts 11 and 12 are first held. Engage with the groove portions 21 and 22 provided in the member 20, and are pushed in the optical axis direction (X direction in FIG. 3) and vertically downward direction (Z direction in FIG. 3) by the holding springs 15 and 16 which are pressing members. The first holding member 20 is pressed and fixed. Here, the rotation of the guide shafts 11 and 12 around the axis is free. In the example of FIG. 3, the guide shafts 11 and 12 having an axial center in the first direction (Y direction) of the reflective optical element 6 are provided so as to protrude on both sides of the outer peripheral portion of the reflective optical element 6. However, even if it is provided only on one side, it can be held.

  The position of the reflective optical element 6 in the directions of the guide shafts 11 and 12 (Y direction in FIG. 3) is different from that of another guide shaft 13 provided outside the reflective surface (free-form mirror surface) 10 of the reflective optical element 6. The position of the first holding member 20 in the Y direction is restricted by the engagement with the groove 23 of the first holding member 20. Further, the gap in the Y direction between the outer periphery of the reflective optical element 6 and the first holding member 20 has a gap that does not allow the reflective optical element 6 and the first holding member 20 to contact each other due to thermal expansion of both components. It is engaged.

  The rotational position of the reflective optical element 6 about the pair of guide shafts 11 and 12 with respect to the first holding member 20 is such that the reflective optical element 6 rotates relative to the first holding member 20 and the outer periphery of the reflective optical element 6 is rotated. As shown in FIG. 4B, the regulating rib 14 attached integrally to the portion is screw-adjusted in the X direction and fixed to the first holding member 20. The regulating rib 14 is sandwiched between a presser spring 19 that receives one end of the first holding member 20 and a holding presser 18 that is screwed into the first holding member 20, and rotates the holding presser 18. The rotation angle of the reflective optical element 6 about the axis of the guide shafts 11 and 12 can be adjusted.

  Next, the attachment of the first holding member 20 to the second holding member 30 is similar to the attachment of the reflective optical element 6, and the guide shafts 24 and 25 of the first holding member 20 are connected to the grooves 31 and 32 of the second holding member 30. The holding springs 34 and 35 are pressed against each other in the X direction.

  Here, the rotation of the guide shafts 24 and 25 around the axis is free. Similarly to the rotation adjustment of the reflection type optical element 6 described above, the rotation position is a structure in which the regulating rib 27 provided on the first holding member 20 is formed using a pressing plate 37, a holding presser 38, and a presser spring 39 (FIG. 4 (b), the holding portion 33 of the second holding member can be adjusted by adjusting the screw in the X direction, and is fixed after adjustment.

Further, the position of the first holding member 20 in the axial direction (Z direction) of the guide shafts 24 and 25 presses the first holding member 20 against the reference surface position of the groove portion 32 of the second holding member 30 by the holding spring 36. Determined by shape.
The reflective optical element 6 and the first holding member 20 are fixed to the regulating rib portions 14 and 27 with an adhesive or the like after the rotation position is adjusted, and the positions are determined.

  Here, the respective axes of the guide shafts 11 and 12 of the reflective optical element 6 and the guide shafts 24 and 25 of the first holding member 20 are the reflection surface (free-form mirror surface) 10 of the reflective optical element 6 and the design. The reflective optical element is in contact with (or located in the vicinity of) the point (reflection point) where the central optical axis of the upper projection screen intersects, and by adjusting the rotation around the guide axis in the two directions. The point where the reflection surface 10 of the (free-form surface mirror) 6 and the central optical axis of the designed projection screen intersect is not moved.

Next, the shape of the reflective optical element 6 will be described with reference to FIG.
FIG. 5 shows an example in which an image is projected onto a screen using the two reflective optical elements 6 and 7 in FIG. 2, and the area within the one-dot chain line at the center of the reflecting surface is within the projection optical system ( This is a reflection surface of the image light from the lens portion 4, and the reflection surface 10 is a concave free-form mirror surface. In the figure, point A is a point where the central principal ray of the projected image is reflected by the mirror surface 10.
The left and right guide shafts 11 and 12 have straight axes, and are perpendicular to the central optical axis of the projection video screen (the central principal ray of the projection video from the lens unit 4) and one side of the projection video screen frame. It is comprised so that it may become parallel.
Here, as described above, the axis of the guide shafts 11 and 12 is configured to be in contact with the point A.

Next, the relationship between the first holding member 20 and the second holding member 30 will be described with reference to FIG.
The guide shafts 24 and 25 provided on the upper and lower portions of the first holding member 20 in FIG. 6 have the same axis, and are perpendicular to the central optical axis of the projection image screen (the central principal ray of the projection image from the lens unit 4). The projection image screen frame is configured to be parallel to one side (one side orthogonal to one side parallel to the guide shafts 11 and 12 of the reflective optical element 6).
Further, at the point B where the axis of the guide shafts 24 and 25 and the axis of the guide shafts 11 and 12 of the reflective optical element 6 intersect, the reflective optical element 6 is attached to the first holding member 20. In such a case, the contact point A is in contact with the point A.

  In the present invention, the tilt adjustment of the reflective optical element 6 of the image projection apparatus 1 is assumed to be rotational adjustment in two directions, and the rotational axis for the adjustment (the guide shafts 11 and 12 of the reflective optical element 6 and the first The axis of the guide shafts 24 and 25 of the holding member 20 is in contact with or near the point (reflection point) A where the reflection surface 10 of the reflective optical element 6 and the central optical axis of the designed projected video image intersect. Therefore, the adjustment is an inclination adjustment based on the center of the projection screen, and the adjustment accuracy and the adjustment time can be shortened.

Hereinafter, the operational effects of the present invention will be described in more detail.
The reflective surface shape of the reflective optical element 6 in the image projection apparatus (image display apparatus) using the reflective optical element 6 is based on the lens used in the projection optical system 4, the relationship between the lens and the projection screen 8, and the like. The surface has been determined, and a lot of adjustment is required to determine its mounting position. Also particularly troublesome in these adjustments is the tilt adjustment of the reflective optical element 6 having an aspherical surface (for example, a surface having a radius of curvature and an aspherical coefficient, a quadric surface, other free-form surface, etc.).
Therefore, in the present invention, as described above, the tilt adjustment of the reflective optical element 6 is assumed to be rotationally adjusted in two directions, and the center axis of the projected image light beam intersects the reflective optical element at the adjustment rotation axis. The structure is in contact with the reflection point.

  On the other hand, when the adjustment rotating shaft is separated from the reflecting surface 10 of the reflective optical element 6 as in the above-described prior art, the reflecting surface corresponding to the projection screen is adjusted to adjust the entire reflecting surface. It will move over the screen range, requiring a lot of adjustment time, and the accuracy of adjustment will be poor. This explanation will be made based on FIGS. 7 (a) and 7 (b).

  FIG. 7A is a schematic diagram in the case of a structure in which the rotation center (axial center) position for adjustment of the reflection surface of the reflective optical element 6 is away from the reflection surface. The reflection surface is aa ′, and the adjustment rotation is performed. It is assumed that the center is designed with an S point. However, in an actual part, there may be a dimensional error h with respect to the design center point S due to an error in manufacturing, thermal expansion of the part due to a temperature change, and the rotation center of adjustment is S1. It may shift.

  Here, it is assumed that the light ray incident on the designed reflection surface a-a ′ is reflected at the point A, and is referred to as an incident light beam 1-A and an outgoing light beam Am. However, since the deviation of the dimensional error h may actually occur as described above, the reflecting surface aa ′ becomes bb ′, the design point A moves to the point B, and the actual light ray is reflected. The point is A1. Naturally, since the reflection surface of A1 is different from the design value, the outgoing light beam is A1-n. Therefore, the reflection surface is rotated and adjusted around S1, is rotated counterclockwise so as to be close to the designed light beam, the reflection surface is cc ', and the inclination of the reflection point is close to the design assumed value. Become. Here, the reflection point moves to A2, the emitted light becomes A2-p, and the point B also moves to C. Therefore, by this adjustment, the point A on the design has finally moved to the point C. This may cause problems such as image distortion and blurring even after adjustment.

Next, FIG. 7B is a schematic diagram in the case of a structure in which the rotation center (axial center) position for adjustment of the reflection surface of the reflective optical element 6 is on the reflection surface, and the reflection surface is aa ′ adjustment. It is assumed that the center of rotation is designed assuming the point A. Then, assuming that the light ray incident on the designed reflection surface aa ′ is reflected at the point A, the light ray is assumed to be an incident light beam 1-A and an outgoing light beam Am.
Assuming the case where the rotational center position of the reflecting surface is on the reflecting surface as described above, when the deviation of the dimensional error h occurs, the reflecting surface changes from aa ′ to bb ′ and is designed. The upper point A moves to the point B, and the actual reflection point of the light ray is A1, and the outgoing light ray is A1-n. Therefore, when the reflection surface is rotated and adjusted around the point B, rotated counterclockwise so as to be close to the designed outgoing light beam, and the reflection surface is cc ′, the reflection point becomes A1 → A2.

As described above, the design point A may be shifted to the point B due to a dimensional error or the like, but when the rotation center (axial center) position of the reflection surface adjustment is on the reflection surface, the rotation center position is B. Therefore, even if the rotation is adjusted, the position of the point B does not move, and the deviation of the position of the reflecting surface after the adjustment becomes small.
That is, as shown in FIG. 7A, when the adjustment center of rotation (axial core) is away from the reflection surface, the position of the design assumed reflection surface may be greatly shifted by the adjustment operation. ), If the center of rotation (axial center) of the adjustment of the reflection surface is on the reflection surface, the position of the reflection surface to be designed will not be greatly shifted even if adjustment is performed. In addition, the adjustment time can be shortened, and problems such as distortion and blurring of the image after adjustment can be reduced.

  Further, in view of the expansion of the reflection surface of the reflection type optical element 6 caused by the thermal change and the movement of the reflection point with respect to the light beam of the appropriate reflection surface caused by this, the adjustment reference point (in the case of the present invention, the reflection type optical element). 6 and the guide axes 24 and 25 of the first holding member 20) at the point where the reflecting surface 10 of the reflective optical element 6 and the center optical axis of the designed projected video image intersect. It is effective in view of the quality of the projected image to be arranged in contact with or in the vicinity thereof, and particularly to be placed at an intermediate position between the top, bottom, left and right of the projected video image.

1: Image projector 2: Image forming element 3: Light guide prism 4: Projection optical system 4a, 4b: Lens unit 5: Reflective optical system 6: Reflective optical element (free curved mirror)
7: Reflective optical element (plane mirror)
8: Screen (projection surface)
10: Reflecting surface (mirror surface)
11, 12: Guide shaft of the reflective optical element 14: Ribs of the reflective optical element 15, 16, 34, 35: Holding spring (pressing member)
20: 1st holding member 21, 22: Groove part 24, 25 of 1st holding member 27: Guide shaft of 1st holding member 27: Rib of 1st holding member 30: 2nd holding member 31, 32: 3rd holding member Groove

JP 2008-139442 A JP 2006-18083 A JP 2007-65053 A Japanese Patent No. 3913265 JP 2007-41544 A

Claims (7)

An image generation unit that generates image light, a projection optical system that projects the image light generated by the image generation unit, and a projection image from the projection optical system is reflected toward a projection surface by a reflective optical element In an image projection apparatus comprising a reflective optical system,
The reflective optical system has a holding structure for holding and fixing the reflective optical element so that the angle can be adjusted by a first holding member and a second holding member,
The reflective optical element has a guide shaft having an axial center in a first direction that is orthogonal to the central optical axis of the projection video screen and parallel to one side of the projection video screen, on the outer peripheral portion outside the reflection surface, The guide shaft is held in a groove provided in the first holding member, and has a degree of freedom of rotation with respect to the first holding member around the shaft in the first direction,
The first holding member holds the reflective optical element, and is provided on the outer periphery of the first holding member in a second direction orthogonal to the first direction, and is orthogonal to the central optical axis of the projection video screen. A guide shaft having an axial center that is held by a groove provided in the second holding member, and freely rotatable with respect to the second holding member around the axis in the second direction. Is a structure with a degree,
The axial center of the guide shaft of the reflective optical element and the guide shaft of the first holding member is in contact with or near the point where the reflective surface of the reflective optical element and the central optical axis of the projection image screen intersect. An image projector characterized by being arranged. The image projector according to claim 1,
The groove portion provided in the first holding member has a structure for holding the guide shaft of the reflective optical element, and the guide shaft is formed on a reference surface in the groove provided to be parallel to the first direction. The presser is fixed to the presser with a degree of freedom of rotation around the shaft.
The groove portion provided in the second holding member has a structure for holding the guide shaft of the first holding member, and the guide shaft is formed on a reference surface in the groove provided to be parallel to the second direction. An image projection apparatus characterized in that the presser is fixed by a pressing member in a form having a degree of freedom of rotation about an axis. The image projector according to claim 1 or 2,
A rib surface parallel to the first direction is provided outside the reflective surface of the reflective optical element, and after the rotation of the reflective optical element around the guide shaft is adjusted, the rib surface is used as the first holding member. In contrast, by restricting the rotational angle position of the reflective optical element with respect to the first holding member,
The first holding member is provided with a rib surface parallel to the second direction, and the rib surface is fixed to the second holding member after adjusting the rotation of the first holding member around the guide shaft. Thus, the image projecting device is characterized in that the rotational angle position of the first holding member with respect to the second holding member is regulated. In the image projection device according to any one of claims 1 to 3,
The position of the reflective optical element in the guide axis direction with respect to the first holding member is provided on the first holding member and a rib provided in a direction orthogonal to the guide axis provided on the outer periphery of the reflective optical element. Determined by the groove to be fitted to the rib,
The attachment margin dimension in the first direction between the reflective optical element and the first holding member includes a difference in linear expansion coefficient of each material, a temperature difference between an upper limit use temperature of the image projector and normal temperature. The dimension in the first direction from the center of the rib provided on the reflective optical element to the guide shaft is larger than the product of the width of the reflective optical element in the first direction. An image projector characterized by being set to be distributed according to the ratio. In the image projection device according to any one of claims 1 to 4,
The first holding member and the second holding member are made of the same material, and the position of the first holding member in the second direction is pushed by a pressing member to a reference surface position provided on the second holding member. An image projection apparatus characterized by having a structure determined by a hitting form. In the image projection device according to any one of claims 1 to 5,
The reflection type optical element has the rib portion bonded and fixed to the groove portion of the first holding member after adjusting the rotational position.   An image projection apparatus according to any one of claims 1 to 6 and a screen which is a projection surface, and image light generated by the image generation unit of the image projection apparatus is transmitted to the projection optical system and the projection optical system. An image display apparatus, wherein the image is enlarged and projected onto the screen by a reflection optical system.

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