JP2017032618A - Image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust and fix the relative positions of a synthesis optical system and a projection optical system by a simple configuration.SOLUTION: An image projection device has a synthesis optical system 101 for synthesizing a plurality of lights modulated by a plurality of optical modulation elements 103-105, and a mount member 109 to which is attached a projection optical system 107 for projecting the plurality of lights that have been synthesized to a projection plane. A cross section that includes optical paths of a plurality of lights heading from the plurality of optical modulation elements to the projection optical system via the synthesis optical system is defined as a first cross section (XY), and a cross section orthogonal to the first cross section and including the optical axis 107a of the projection optical system is defined as a second cross section (XZ). A holding member 102 is had that is shaped to provide the center of rotation of the synthesis optical system in adjusting the rotation position of the mount member in the first cross section of the synthesis optical system, and to which the synthesis optical system after the adjustment is fixed. An adjusting member 108b is had between the holding member and the mount member that is used in adjusting the relative rotation positions of the holding member and the mount member in the second cross section.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image projection apparatus (hereinafter referred to as a projector) using a light modulation element such as a liquid crystal panel.

  With the downsizing of projectors and high definition of projected images, the pixel pitch of light modulation elements used in projectors is reduced, and the resolution performance of projection optical systems (projection lenses) is required to be improved. In general, the depth of focus of the projection lens is proportional to the product of the pixel pitch of the light modulation element and the F number of the illumination optical system that illuminates the light modulation element. That is, the depth of focus is reduced by improving the brightness and reducing the pixel pitch.

When the focal depth of the projection lens is reduced, the projection image quality is deteriorated, for example, the projection image is blurred due to a mechanical error due to the tilt or eccentricity of the projection lens. Furthermore, in projectors that modulate multiple color lights with multiple light modulation elements and combine the modulated multiple color lights with a composite optical system to guide the projection lens, manufacturing errors and mounting errors of the composite optical system also affect the projection image quality. To do. For this reason, it is necessary to make a relative assembly adjustment between the combining optical system and the projection lens (and also the light modulation element).

In Patent Document 1, the rotational position of the color synthesis optical system with respect to the fixed plate can be adjusted in the first cross section including the optical paths of the plurality of color lights to be synthesized, and the second cross section is orthogonal to the first cross section. An apparatus for manufacturing a color synthesis optical system capable of adjusting the tilt position of the color synthesis optical system is disclosed.

Japanese Patent No. 3716767

  However, the manufacturing apparatus disclosed in Patent Document 1 has a complicated configuration and is easily increased in size. In addition, since the shape of the bonding portion of the prism constituting the color synthesis optical system to the fixing plate has an unstable shape such as a spherical surface, it is difficult to maintain the positional accuracy of the prism after bonding.

  The present invention provides an image projection apparatus capable of satisfactorily performing relative position adjustment and subsequent fixing between a combining optical system and a projection optical system, although having a simple configuration.

  An image projection apparatus according to one aspect of the present invention is composed of a plurality of light modulation elements, a combination optical system that combines a plurality of lights modulated by each of the plurality of light modulation elements, and the combination optical system. And a mount member to which a projection optical system for projecting a plurality of lights onto a projection surface is attached. A cross section including a plurality of optical paths of light from a plurality of light modulation elements to a projection optical system attached to the mount member via a synthesis optical system is defined as a first cross section, and the projection optical system is orthogonal to the first cross section. A cross section including the optical axis is defined as a second cross section. At this time, a holding member having a shape that gives a rotation center of the composite optical system in the adjustment of the rotational position of the composite optical system with respect to the mount member in the first cross section, to which the adjusted composite optical system is fixed And an adjusting member used for adjusting the relative rotational position of the holding member and the mount member in the second cross section between the holding member and the mount member.

  According to another aspect of the present invention, there is provided a method of manufacturing an image projection apparatus, comprising: a plurality of light modulation elements; a combination optical system that combines a plurality of lights modulated by each of the plurality of light modulation elements; An image projection apparatus having a mount member to which a projection optical system for projecting a plurality of lights synthesized by the synthesis optical system onto a projection surface is manufactured. In the method, a cross section including a plurality of light paths of light from a plurality of light modulation elements to a projection optical system attached to a mount member via a synthesis optical system is defined as a first cross section, and is orthogonal to the first cross section. When the cross section including the optical axis of the projection optical system is the second cross section, the holding member that holds the composite optical system is provided with a shape that gives the composite optical system a center of rotation within the first cross section, and the rotation Using the center, the rotational position of the composite optical system in the first cross section relative to the mount member is adjusted, the composite optical system after the rotational position is adjusted is fixed to the holding member, and between the holding member and the mount member Using the arranged adjustment member, the relative rotation position of the holding member and the mount member in the second cross section is adjusted, and the mount member and the holding member after the adjustment of the relative rotation position are fixed. To do.

  According to the present invention, the relative rotational position between the combining optical system and the mount member (projection optical system) in the first and second cross sections and the subsequent fixing thereof are simple in structure. And can be performed satisfactorily.

1 is a top view of a prism unit used in a transmissive liquid crystal projector that is Embodiment 1 of the present invention. FIG. FIG. 3 is a perspective view of the prism unit according to the first embodiment. FIG. 3 is a side view of the prism unit according to the first embodiment. FIG. 6 is a side view of a prism unit as a modification of the first embodiment. FIG. 9 is a side view of a prism unit as another modification of the first embodiment. Sectional drawing which shows the optical structure of the reflection type liquid crystal projector which is Example 2 of this invention. FIG. 10 is a top view of a prism unit used in the projector according to the second embodiment. FIG. 6 is a perspective view of a prism unit according to Embodiment 2. FIG. 6 is a side view of the prism unit according to the second embodiment. FIG. 10 is a side view of a prism unit as a modification of the second embodiment. FIG. 10 is a side view of a prism unit as another modification of the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a prism unit in a transmissive liquid crystal projector as an image projection apparatus that is Embodiment 1 of the present invention. Reference numeral 101 denotes a cross prism constituting the color synthesis optical system. The cross prism 101 is a cubic or rectangular prism type optical element having dichroic surfaces 101a and 101b as optical film surfaces orthogonal to each other. The cross prism 101 is manufactured by bonding together four triangular prism-shaped prism pieces on which the dichroic surface 101a or 101b is formed.

  Around the cross prism 101, green (G), blue (B), and red (R) transmissive liquid crystal panels (hereinafter referred to as G, B, and R panels, respectively) 103, 104 as a plurality of light modulation elements. , 105 are arranged.

  The G, B, and R panels 103, 104, and 105 respectively display G light, B light, and R light as illumination light from a color separation optical system (not shown) that separates light (white light) from a light source. Incident from the direction indicated by the white arrow inside. The G, B, and R panels 103, 104, and 105 modulate and transmit the incident G light, B light, and R light, respectively. The image-modulated G light, B light, and R light are incident on the cross prism 101 from different incident surfaces 101 d, 101 e, 101 f of the cross prism 101. The G light is reflected by the dichroic surface 101 b and travels toward the exit surface 101 c of the cross prism 101. The R light is reflected by the dichroic surface 101a and travels toward the exit surface 101c. Further, the B light passes through the dichroic surfaces 101a and 101b and travels toward the emission surface 101c. Thus, the G light, the B light, and the R light are combined to exit the cross prism 101 from the exit surface 101c and enter the projection lens (projection optical system) 107. The projection lens 107 impinges on a projection surface such as a screen (not shown). Projected. Thereby, the projection image as a color image is displayed on the projection surface.

  Reference numeral 102 denotes a prism base as a holding member that holds the cross prism 101. Reference numeral 109 denotes a mount member to which the projection lens 107 is attached. Note that the projection lens 107 may be fixedly attached (not replaceable) to the mount member 109 or may be attached and detached (replaceable).

  In this embodiment, as shown in FIG. 1, G light, B light, and R light traveling from the G, B, and R panels 103, 104, and 105 toward the projection lens 107 attached to the mount member 109 via the cross prism 101. A cross section including the optical path is defined as a first cross section. In the following description, the first cross section is referred to as an XY cross section.

  In the XY section, the projection lens 107 is formed on the outer surface (the exit surface 101c and the entrance surfaces 101d, 101e, and 101f) as the optical surface of the cross prism 101 due to manufacturing errors such as polishing errors and prism piece bonding errors. Is inclined with respect to the optical axis 107a. Here, the optical axis 107a extends not only straight toward the exit surface 101c and the entrance surface 101e of the cross prism 101, but also bends toward the entrance surfaces 101d and 101f due to reflection at the dichroic surfaces 101a and 101b. It shall be extended.

  The inclination of the outer surfaces 101 c to 101 f of the cross prism 101 with respect to the optical axis 107 a of the projection lens 107 affects the resolution performance of the projection lens 107. Specifically, when these pixel sizes are reduced by downsizing the G, B, and R panels 103, 104, and 105, the angle formed by the outer surfaces 101 c to 101 f of the cross prism 101 and the optical axis 107 a of the projection lens 107 is increased. Deviation from 90 degrees. As a result, the resolution of the projection lens 107 decreases. In order to cancel the inclination of each outer surface of the cross prism 101 with respect to the optical axis 107a of the projection lens 107, it is necessary to be able to adjust the rotational position of the cross prism 101 with respect to the projection lens 107 in the XY section. That is, by adjusting the rotational position of the cross prism 101, it is necessary to match the optical axis 107a of the projection lens 107 with the normal line of each outer surface of the cross prism 101.

  Hereinafter, the projector according to the present embodiment includes the relative rotational position adjustment in the XY cross section of the cross prism 101 and the projection lens 107 and the XZ cross section which is the second cross section including the optical axis 107a of the projection lens 107 orthogonal to the cross section. The manufacturing method will be described.

  FIG. 2 shows a prism adjustment structure that can adjust the rotational position of the cross prism 101 with respect to the projection lens 107 attached to the mount member 109 in the XY cross section (in the first cross section). A round hole 111 is formed on the pedestal surface of the prism pedestal 102, and a cylindrical shaft member 110 is bonded to the bottom surface of the cross prism 101 (the prism outer surface orthogonal to the dichroic surfaces 101a and 101b). Yes. The position of the shaft member 110 is a position corresponding to a position where the dichroic surfaces 101a and 101b intersect (hereinafter referred to as the center of the dichroic surface).

  The shaft member 110 is inserted into the hole 111. The bottom surface of the cross prism 101 is in contact with the base surface of the prism base 102. According to this configuration, the cross prism 101 is moved to the prism pedestal 102 around the rotation center provided by the shaft member 110 and the hole 111 in the XY section while sliding the bottom surface of the cross prism 101 with respect to the pedestal surface of the prism pedestal 102. Can be rotated. In other words, the cross prism 101 can be rotated in the XY section with respect to the projection lens 107 around the center of the dichroic surface.

  After the rotation position of the cross prism 101 is adjusted, the bottom surface of the cross prism 101 is bonded to the base surface (plane) of the prism base 102. Thereby, the rotational position of the cross prism 101 with respect to the optical axis 107a of the projection lens 107 in the XY section can be stably fixed (maintained).

  Instead of such a prism adjustment structure, as shown in the upper right side of FIG. 2, one corner of the cross prism 101 is shifted to the positioning pin 102b provided on the prism base 102, and the cross prism 101 is moved to the positioning pin 102b. You may use the structure rotated on the basis of. At this time, the rotational position of the cross prism 101 can be fixed by inserting an adjusting member such as a washer between the positioning pin 102 b and the cross prism 101.

  FIG. 3 shows the configuration of the prism unit in the XZ section. In FIG. 3, due to the manufacturing error of the cross prism 101, the cross prism 101 (outer surface thereof) has an inclination φ with respect to the optical axis 107 a of the projection lens 107, and adjustment to cancel this inclination is necessary. It becomes. In this embodiment, the rotational position of the cross prism 101 can be adjusted by rotating the cross prism 101 with respect to the prism base 102 and the projection lens 107 (mount member 109) in the XY section. On the other hand, in the XZ section, the tilt φ is canceled by rotating the mount member 109 with respect to the cross prism 101, and the optical axis 107a of the projection lens 107 coincides with the normal line of each outer surface of the cross prism 101. Let

  In FIG. 3, a mount adjustment structure is provided between a wall portion provided on the prism base 102 so as to extend perpendicular to the base surface and the mount member 109. The mount adjustment structure has a rotation connecting portion 108 in which a shaft portion provided so as to extend in the Y direction is brought into contact with a mount member 109 in a V groove portion formed in a wall portion of the prism base 102. As a result, the mount member 109 can be rotated relative to the prism base 102 within the XZ cross section (in the second cross section).

  Further, a spring member 108a and a wedge-shaped slide 108b as an adjustment member are provided on one and the other side in the Z direction across the rotation connecting portion 108 between the wall portion of the prism base 102 and the mount member 109, respectively. ing. The wedge-shaped slide 108b moves in the Z direction by rotating the screw 108c, and changes the distance between the wall portion of the prism base 102 and the mount member 109. As a result, the mount member 109 rotates within the XZ cross section around the rotation connecting portion 108. According to this configuration, the rotational position of the mount member 109 (that is, the optical axis 107a of the projection lens 107) within the XZ section can be adjusted steplessly with respect to the cross prism 101 on the prism base 102.

  Instead of the wedge-shaped slide 108b, the rotational positions of the mount member 109 and the projection lens 107 are adjusted by inserting another adjustment member such as a washer between the mount member 109 and the wall of the prism base 102. You can also

  After the rotation position of the mount member 109 is adjusted, the mount member 109 is bonded to the wall portion of the prism base 102. Thereby, the rotation position of the optical axis 107a of the mount member 109 and the projection lens 107 with respect to the cross prism 101 in the XZ cross section can be stably fixed (maintained).

  Here, if the distance between the projection lens 107 and the G, B, and R panels 103, 104, and 105 on the optical axis 107a of the projection lens 107 varies due to the rotation of the mount member 109 and the projection lens 107, the resolution of the projection lens 107 is resolved. Performance deteriorates. In order that the distance does not change due to the rotation of the projection lens 107, the normal line of the outer surfaces (101c to 101f) of the cross prism 101 is kept coincident with the optical axis 107a of the projection lens 107 during the rotation. You can do so. In the present embodiment, as shown in FIG. 3, a rotation connecting portion 108 serving as the rotation center of the projection lens 107 is provided at a position overlapping the optical axis 107 a of the projection lens 107 in the XZ section. Thereby, it is possible to avoid the distance between the projection lens 107 and the G, B, and R panels 103, 104, and 105 from being changed by the rotation of the projection lens 107.

  Further, as the optical axis 107a of the projection lens 107 is rotated with respect to the cross prism 101 on the prism base 102, the G, B, and R panels 103, 104, and 105 have the optical axis 107a positioned at the center thereof, and It is necessary to move so as to be orthogonal to the optical axis 107a. However, when each panel is moved greatly from the position indicated by the dotted line in FIG. 3 to a position indicated by the solid line, a part of the panel is removed from the incident area of the illumination light 110 from the color separation optical system, and as a result, the projected image is missing. May occur.

  Therefore, as shown in the lower right part of FIG. 3, an elongated hole portion 108d as a guide portion is formed in the rotary connecting portion 108, and the shaft portion 108e provided in the mount member 109 is parallel to the Z direction in the elongated hole portion 108d. It shall be a slidable configuration. Then, after adjusting the rotational position of the projection lens 107 in the XZ section, the projection lens 107 is slid in parallel in the Z direction so that the position of each panel does not deviate from the incident area of the illumination light 110. The position of the 107a in the Z direction is adjusted.

  Further, instead of the mount adjustment structure shown in FIG. 3, as shown in FIG. 4, a pedestal adjustment structure that allows the prism pedestal 102 to rotate within the XZ section with respect to the optical axis 107a of the projection lens 107 is adopted. Also good. In this case, the inclination φ of the cross prism 101 with respect to the optical axis 107a of the projection lens 107 is canceled, that is, the normal line of the outer surface (101c to 101f) of the cross prism 101 is made to coincide with the optical axis 107a of the projection lens 107. The prism base 102 is rotated. According to this configuration, the relative position in the XZ cross section between the outer surface of the cross prism 101 and the optical axis 107a of the projection lens 107 without causing the position of each panel to deviate from the incident region of the illumination light 110 (a relationship orthogonal to each other). Can be set appropriately.

  Further, in FIG. 5, a shift mechanism 111 is provided between the wall portion of the prism base 102 and the mount member 109 as a guide portion that guides the projection lens 107 so that its optical axis 107 a is shifted in the Z direction. Also good. In this case, the above-described rotation connecting portion 108 (but not having the long hole portion 108d) is provided between the shift mechanism 111 (that is, the mount member 109) and the wall portion of the prism pedestal 102, and Adjust the rotational position in the XZ cross section. Thereafter, the position of each panel in the Z direction may be adjusted using the shift mechanism 111 so that the position of each panel does not deviate from the incident area of the illumination light 110.

  According to the present embodiment, although the configuration is simple, the relative rotational position of the dichroic prism 101 and the mount member 109 (that is, the projection lens 107) in the XY and XZ cross sections is adjusted, and the subsequent fixing is performed. Can be performed satisfactorily.

  FIG. 6 shows an optical configuration of a reflective liquid crystal projector as an image projection apparatus that is Embodiment 2 of the present invention. In FIG. 6, a horizontal section (XZ section) is shown on the left side, and a vertical section (XY section) is shown on the right side.

  Reference numeral 41 denotes a discharge arc tube (hereinafter simply referred to as an arc tube) that emits white light in a continuous spectrum. Reference numeral 42 denotes a reflector having a concave mirror that condenses light from the arc tube 41 in a predetermined direction. The light source lamp 1 is constituted by the arc tube 41 and the reflector 42.

  Reference numeral 43a denotes a first cylinder array in which a plurality of cylindrical lens cells having refractive power in the horizontal direction are arranged. 43b is a second cylinder array having a plurality of cylindrical lens cells corresponding to the individual lens cells of the first cylinder array 43a. 44 is an ultraviolet absorption filter, and 45 is a polarization conversion element that converts non-polarized light into predetermined polarized light.

  A front compressor 46 is constituted by a cylindrical lens having a refractive power in the vertical direction. Reference numeral 47 denotes a reflection mirror for bending the optical axis from the lamp 1 by approximately 90 degrees (more specifically, 88 degrees).

  43c is a third cylinder array in which a plurality of cylindrical lens cells having refractive power in the vertical direction are arranged. 43d is a fourth cylinder array having a plurality of cylindrical lens arrays corresponding to individual lens cells of the third cylinder array 43c.

  Reference numeral 50 denotes a color filter for returning the color in a specific wavelength region to the lamp 1 in order to adjust the color coordinates to a predetermined value. Reference numeral 48 denotes a condenser lens. Reference numeral 49 denotes a rear compressor composed of a cylindrical lens having a refractive power in the vertical direction. The illumination optical system α is configured as described above.

  Reference numeral 58 denotes a dichroic mirror that reflects light in the blue (B) and red (R) wavelength regions and transmits light in the green (G) wavelength region. 59 is an incident side polarizing plate for G in which a polarizing element is bonded to a transparent substrate, and transmits only P-polarized light. Reference numeral 60 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light on a polarization separation surface constituted by a multilayer film.

  61R, 61G, and 61B are a red reflective liquid crystal panel, a green reflective liquid crystal panel, and a blue reflective liquid crystal panel as light modulation elements that reflect incident light and modulate an image, respectively. 62R, 62G, and 62B are a red wavelength plate, a green wavelength plate, and a blue wavelength plate, respectively.

  A trimming filter 64a returns orange light to the lamp 1 in order to increase the color purity of the R light. Reference numeral 64b denotes an incident-side polarizing plate for RB in which a polarizing element is attached to a transparent substrate and transmits only P-polarized light.

  65 is a color selective phase difference plate that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 66 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light on the polarization separation surface.

  Reference numeral 68B denotes a B-use exit side polarizing plate that rectifies only the S-polarized light component of the B light. 68G is a G output-side polarizing plate that transmits only the S-polarized light component of the G light. Reference numeral 69 denotes a dichroic prism that transmits R light and B light and reflects G light.

  The above dichroic mirror 58 to dichroic prism 69 constitute a color separation / synthesis optical system β.

  In this embodiment, the polarization conversion element 45 converts P-polarized light to S-polarized light. The P-polarized light and S-polarized light described here are described with reference to the polarization direction of light in the polarization conversion element 45. On the other hand, the light incident on the dichroic mirror 58 is assumed to be P-polarized light considering the polarization directions in the first and second polarization beam splitters 60 and 66 as a reference. That is, in this embodiment, the light emitted from the polarization conversion element 45 is S-polarized light, but when the same S-polarized light is incident on the dichroic mirror 58, it is defined as P-polarized light.

  Next, the optical action will be described. Light emitted from the arc tube 41 is collected in a predetermined direction by the reflector 42. The reflector 42 has a parabolic concave mirror, and light from the focal position of the paraboloid becomes a light beam parallel to the symmetry axis of the paraboloid. However, since the light source from the arc tube 41 is not an ideal point light source and has a finite size, the condensed light flux includes many light components that are not parallel to the symmetry axis of the paraboloid. ing. These light beams are incident on the first cylinder array 43a. The light beam incident on the first cylinder array 43a is divided into a plurality of light beams corresponding to the number of cylinder lens cells and collected to form a plurality of strip-shaped light beams arranged in the vertical direction. The plurality of split light beams pass through the ultraviolet absorption filter 44 and the second cylinder array 43b to form a plurality of light source images in the vicinity of the polarization conversion element 45.

  The polarization conversion element 45 has a polarization separation surface, a reflection surface, and a half-wave plate. A plurality of light beams are incident on a polarization separation surface corresponding to each column, and are divided into a P-polarized component that transmits the light and an S-polarized component that is reflected there. The reflected S-polarized component is reflected by the reflecting surface and emitted in the same direction as the P-polarized component. On the other hand, the P-polarized component transmitted through the polarization splitting surface is transmitted through the half-wave plate and converted into the same polarized component as the S-polarized component. Thus, a plurality of light beams having the same polarization direction are emitted.

  The plurality of polarization-converted light beams are emitted from the polarization conversion element 45, compressed by the front compressor 46, reflected by the reflection mirror 47, and incident on the third cylinder array 43c.

  The light beam incident on the third cylinder array 43c is divided into a plurality of light beams corresponding to the number of cylinder lens cells and collected to form a plurality of strip-shaped light beams arranged in the horizontal direction. The plurality of split light beams enter the rear compressor 49 via the fourth cylinder array 43d and the condenser lens 48.

  By the optical action of the front compressor 46, the condenser lens 48, and the rear compressor 49, rectangular images formed by a plurality of light beams overlap each other to form a rectangular uniform brightness illumination area. Reflective liquid crystal panels 61R, 61G, and 61B are disposed in this illumination area.

  The light converted to S-polarized light by the polarization conversion element 45 enters the dichroic mirror 58. Hereinafter, the optical path of the G light transmitted through the dichroic mirror 58 will be described.

  The G light transmitted through the dichroic mirror 58 enters the incident side polarizing plate 59. Even after being decomposed by the dichroic mirror 58, the G light remains P-polarized light (S-polarized light when the polarization conversion element 45 is used as a reference). The G light exits from the incident-side polarizing plate 59 and then enters the first polarizing beam splitter 60 as P-polarized light, passes through the polarization separation surface, and reaches the G-use reflective liquid crystal panel 61G.

  Here, an image supply device (not shown) such as a personal computer, a DVD player, and a TV tuner is connected to the control board (not shown) of the projector. The control board drives the reflective liquid crystal panels 61R, 61G, and 61B based on the image information input from the image supply device, and forms an original image for each color on them. Thereby, the light incident on each reflective liquid crystal panel is reflected and modulated (image modulation) according to the original image. An image display system is configured by the image supply device and the projector.

  In the G reflective liquid crystal panel 61G, the G light is image-modulated and reflected. The P-polarized component of the image-modulated G light is again transmitted through the polarization separation surface of the first polarization beam splitter 60, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized component of the image-modulated G light is reflected by the polarization separation surface of the first polarization beam splitter 60 and travels toward the dichroic prism 69 as projection light.

  At this time, in a state where all the polarization components are converted to P-polarized light (in a state where black is displayed), a quarter-wave plate 62G provided between the first polarizing beam splitter 60 and the G-use reflective liquid crystal panel 61G. The slow axis is adjusted in a predetermined direction. Thereby, the influence of the disturbance of the polarization state which generate | occur | produces with the 1st polarizing beam splitter 60 and the reflective liquid crystal panel 61G for G can be restrained small.

  The G light emitted from the first polarization beam splitter 60 enters the dichroic prism 69 as S-polarized light, is reflected by the dichroic surface of the dichroic prism 69, and reaches the projection lens 5.

  On the other hand, the R light and B light reflected by the dichroic mirror 58 enter the trimming filter 64a. R light and B light are still P-polarized light after being decomposed by the dichroic mirror 58. Then, after the orange light component is cut by the trimming filter 64 a, the R light and the B light are transmitted through the incident-side polarizing plate 64 b and are incident on the color selective phase difference plate 65.

  The color-selective phase difference plate 65 has an action of rotating only the polarization direction of the R light by 90 degrees, so that the R light is incident on the second polarization beam splitter 66 as S-polarized light and the B light is incident on P-polarized light.

  The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R-use reflective liquid crystal panel 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light is transmitted through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal panel 61B.

  The R light incident on the R reflective liquid crystal panel 61R is image-modulated and reflected. The S-polarized component of the image-modulated R light is reflected again by the polarization separation surface of the second polarization beam splitter 66, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized component of the image-modulated R light passes through the polarization separation surface of the second polarization beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  The B light incident on the B-use reflective liquid crystal panel 61B is image-modulated and reflected. The P-polarized component of the image-modulated B light is transmitted again through the polarization separation surface of the second polarization beam splitter 66 and returned to the light source side, and is removed from the projection light. On the other hand, the S-polarized component of the image-modulated B light is reflected by the polarization separation surface of the second polarization beam splitter 66 and travels toward the dichroic prism 69 as projection light.

  At this time, by adjusting the slow axes of the quarter-wave plates 62R and 62B provided between the second polarizing beam splitter 66 and the R and B reflective liquid crystal panels 61R and 61B, As in the case, the adjustment in the black display state of each of the R and B lights can be performed.

  The R light and B light that are combined into one light beam and emitted from the second polarization beam splitter 66 are analyzed by the emission side polarizing plate 68B and enter the dichroic prism 69. Further, the R light is transmitted through the exit-side polarizing plate 68 </ b> B as P-polarized light and enters the dichroic prism 69.

  By being analyzed by the exit-side polarizing plate 68B, the B light is ineffective generated by the B light passing through the second polarizing beam splitter 66, the B reflective liquid crystal panel 61B, and the quarter wavelength plate 62B. The light is cut from the components.

  The R light and B light incident on the dichroic prism 69 are transmitted through the dichroic surface and are combined with the G light reflected by the dichroic surface to reach the projection lens 5.

  The combined R, G, B light is enlarged and projected onto a projection surface such as a screen by the projection lens 5.

  The optical path described above is when the reflective liquid crystal panel is in the white display state. Hereinafter, the optical path when the reflective liquid crystal panel is in the black display state will be described.

  First, the optical path of G light will be described. The P-polarized light of the G light that has passed through the dichroic mirror 58 enters the incident-side polarizing plate 59, then enters the first polarizing beam splitter 60, is transmitted through the polarization separation surface, and is transmitted to the G reflective liquid crystal panel 61G. And so on. However, since the reflective liquid crystal panel 61G is in the black display state, the G light is reflected without being image-modulated. For this reason, even after being reflected by the reflective liquid crystal panel 61G for G, the G light remains P-polarized light. Therefore, the G light again passes through the polarization separation surface of the first polarization beam splitter 60, passes through the incident-side polarizing plate 59, returns to the light source side, and is removed from the projection light.

  Next, the optical paths of R light and B light will be described. The P-polarized light of R light and B light reflected by the dichroic mirror 58 is incident on the incident side polarizing plate 64b. Then, after exiting from the incident side polarizing plate 64 b, the light enters the color selective phase difference plate 65. Since the color-selective phase difference plate 65 has an action of rotating only the polarization direction of the R light by 90 degrees, the R light is incident on the second polarization beam splitter 66 as S-polarized light and the B light is incident on P-polarized light.

  The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface and reaches the R-use reflective liquid crystal panel 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light passes through the polarization separation surface and reaches the B-use reflective liquid crystal panel 61B.

  Here, since the R reflective liquid crystal panel 61R is in a black display state, the R light incident on the R reflective liquid crystal panel 61R is reflected without being image-modulated. For this reason, even after being reflected by the reflective liquid crystal panel 61R for R, the R light remains S-polarized light. Accordingly, the R light is reflected again by the polarization separation surface of the second polarization beam splitter 66, passes through the incident-side polarizing plate 64b, returns to the light source side, and is removed from the projection light. Thereby, black display is performed.

  On the other hand, the B light incident on the B reflective liquid crystal panel 61B is reflected without being image-modulated because the B reflective liquid crystal panel 61B is in the black display state. For this reason, even after being reflected by the reflective liquid crystal panel 61B for B, the B light remains P-polarized light. Therefore, the B light again passes through the polarization separation surface of the second polarizing beam splitter 66, is converted to P-polarized light by the color-selective retardation plate 65, passes through the incident-side polarizing plate 64b, and is returned to the light source side. Removed from the projected light.

  FIG. 8 shows the configuration of the prism unit in the projector of the present embodiment in the XY section (first section).

  Reference numerals 114 and 113 respectively denote a first prism and a second prism as cubic or rectangular prism optical elements corresponding to the first polarizing beam splitter 60 and the second polarizing beam splitter 66 shown in FIG. Reference numeral 112 denotes a third prism as a cubic or cuboid prism type optical element corresponding to the dichroic prism 69 shown in FIG. The first and second prisms 114 and 113 have polarization separation surfaces 114a and 113a as optical film surfaces, respectively, and the third prism 112 has a dichroic surface 112a as an optical film surface. Each prism is manufactured by bonding together two triangular prism pieces each having an optical film surface. These first, second and third prisms 113, 114 and 112 constitute a combining optical system. The first, second, and third prisms 113, 114, and 112 are connected to each other by bonding their bottom surfaces (prism outer surfaces orthogonal to the optical film surface) to the holding surface (plane) of the prism connection member 118. It is fixed to the member 118.

  Reference numerals 115, 116, and 117 denote a B panel, an R panel, and a G panel, respectively, corresponding to the reflective liquid crystal panels 61B, 61R, and 61G shown in FIG. Reference numeral 107 denotes a projection lens corresponding to the projection lens 5 shown in FIG. 6, and 107a denotes its optical axis.

  As described with reference to FIG. 6, G light is incident on the first prism 114 and B light and R light are incident on the second prism 113 from directions indicated by white arrows in the drawing. The G light reflected by the polarization separation surface 114a of the first prism 114 is transmitted by the G panel 117, and the B light and R light transmitted and reflected by the polarization separation surface 113a of the second prism 113 are respectively transmitted to the B panel 115 and R. The image is modulated and reflected by the panel 116. The image-modulated G light is transmitted through the polarization separation surface 114a of the first prism 114, and the image-modulated B light and R light are reflected and transmitted by the polarization separation surface 113a of the second prism 113, respectively. Then, the light enters the third prism 112. The G light reflected by the dichroic surface 112 a of the third prism 112 and the B light and R light transmitted through the dichroic surface 112 a are combined and directed to the projection lens 107. As a result, the projection lens 107 projects onto a projection surface such as a screen (not shown), and a projection image as a color image is displayed on the projection surface.

  Reference numeral 109 denotes a mount member to which the projection lens 107 is attached. Note that the projection lens 107 may be fixedly attached (not replaceable) to the mount member 109 or may be attached and detached (replaceable).

  As shown in FIG. 7, the G, B, and R panels 117, 115, and 116 go through the first, second, and third prisms 114, 113, and 112 toward the projection lens 107 attached to the mount member 109. A cross section including optical paths of light, B light, and R light is an XY cross section.

  The first, second, and third prisms 114, 113, and 112 have outer surfaces (114b, 114c, 113b, 113c, 113d, 112c, and 112d) as optical surfaces. In the XY cross section, these external surfaces are inclined with respect to the optical axis 107a of the projection lens 107 due to manufacturing errors such as polishing error and prism piece bonding error. The optical axis 107a extends straight toward the outer surfaces 112b, 112c, 113b, 113c of the third and second prisms 112, 113. Further, it is assumed that the optical axis 107a is bent and extended toward the outer surfaces 113d, 114b, and 114c due to reflection on the dichroic surface 112a and the polarization separation surface 113a.

  The inclination of the outer surface of each prism with respect to the optical axis 107 a of the projection lens 107 affects the resolution performance of the projection lens 107. Specifically, when these pixel sizes are reduced due to the miniaturization of the G, B, and R panels 117, 115, and 116, the angle formed between the outer surface of each prism and the optical axis 107a of the projection lens 107 deviates from 90 degrees. As a result, the resolution of the projection lens 107 decreases. In order to cancel the inclination of the outer surface of each prism with respect to the optical axis 107a of the projection lens 107 (to match the optical axis 107a with the normal of each outer surface), each prism with respect to the projection lens 107 in the XY cross section. It is necessary to be able to adjust the rotation position. Hereinafter, a method of manufacturing the projector according to the present embodiment including the relative rotational position adjustment of the first, second, and third prisms 114, 113, 112 and the projection lens 107 in the XY section and the XZ section will be described.

  In FIG. 8, the rotational positions of the first, second, and third prisms 114, 113, and 112 with respect to the projection lens 107 attached to the mount member 109 can be adjusted in the XY cross section (in the first cross section). The prism adjustment structure is shown. A round hole 123a is formed on the base surface of the prism base 123 as a holding member. A cylindrical shaft member 119 is bonded to the lower surface of the prism coupling member 118 (a surface parallel to the prism outer surface orthogonal to the polarization separation surfaces 114a and 113a and the dichroic surface 112a). The position of the shaft member 119 is a position corresponding to a position where the plane including the polarization separation surfaces 114a and 113a and the plane including the dichroic surface 112a intersect (hereinafter referred to as the center of the optical film surface).

  The shaft member 119 is inserted into the hole 111. The lower surface of the prism coupling member 118 is in contact with the pedestal surface (plane) of the prism pedestal 123. According to this configuration, the prism coupling member 118 has its lower surface slid with respect to the pedestal surface of the prism pedestal 123, and the prism pedestal 123 around the rotation center provided by the shaft member 110 and the hole 111 in the XY cross section. Can be rotated. In other words, the first, second, and third prisms 114, 113, and 112 can be rotated in the XY section with respect to the projection lens 107 around the center of the optical film surface.

  After adjusting the rotational positions of the first, second, and third prisms 114, 113, and 112, the lower surface of the prism coupling member 118 is bonded to the base surface of the prism base 123. Thereby, the rotational positions of the first, second, and third prisms 114, 113, and 112 relative to the optical axis 107a of the projection lens 107 in the XY cross section can be stably fixed (maintained).

  Instead of this prism adjustment structure, as shown in the upper right side of FIG. 2 in the first embodiment, one corner of the third prism 112 is shifted to a positioning pin provided on the prism base 123, and a prism connecting member A structure in which 118 is rotated with reference to the positioning pin may be used. At this time, by inserting an adjusting member such as a washer between the positioning pin and the third prism 112, the rotational positions of the first, second, and third prisms 114, 113, and 112 can be fixed. .

  FIG. 9 shows the configuration of the prism unit in the XZ section as the second section including the optical axis 107a of the projection lens 107 orthogonal to the XY section. In FIG. 9, the first, second, and third prisms 114, 113, and 112 (outer surfaces thereof) have an inclination φ with respect to the optical axis 107a of the projection lens 107 due to manufacturing errors, and the inclination is canceled. Adjustments are required. In the present embodiment, in the XY cross section, the prism coupling member 118 to which the first, second, and third prisms 114, 113, and 112 are fixed is rotated with respect to the prism base 123 and the projection lens 107 (mount member 109). The rotational position of each prism can be adjusted. On the other hand, in the XZ cross section, the tilt φ is canceled by rotating the mount member 109 with respect to the first, second and third prisms 114, 113 and 112. Thereby, the optical axis 107a of the projection lens 107 is made to coincide with the normal line of each outer surface of the first, second and third prisms 114, 113 and 112.

  In FIG. 9, a mount adjustment structure is provided between a wall portion provided on the prism base 123 so as to extend perpendicularly to the base surface and the mount member 109. As in the first embodiment, the mount adjustment structure includes a rotation connecting portion 108 in which a shaft portion provided to extend in the Y direction on the mount member 109 is in contact with a V groove formed in the wall portion of the prism base 123. Have. As a result, the mount member 109 can be rotated relative to the prism base 123 within the XZ cross section (in the second cross section).

  Also in this embodiment, for the reason described in the first embodiment, the rotation connecting portion 108 serving as the rotation center of the projection lens 107 is provided at a position overlapping the optical axis 107a of the projection lens 107 in the XZ section. Thereby, it is possible to avoid the distance between the projection lens 107 and the G, B, and R panels 117, 115, 116 due to the rotation of the projection lens 107. That is, in the case where there is no rotation connecting portion, the same effect can be obtained by inserting washer parts (not shown) having different thicknesses into the four corners between the mount member 109 and the prism base 123 or the like. However, since it is necessary to adjust only the angle so that the distance between the projection lens 107 and the G, B, and R panels 117, 115, and 116 does not fluctuate, the work of adjusting the thickness of the washer takes a very long time to adjust. Takes and becomes difficult.

  Similarly to the first embodiment, a spring member and a wedge-shaped slide (adjustment member) are respectively provided on one side and the other side in the Z direction across the rotation shaft portion 108 between the wall portion of the prism base 123 and the mount member 109. It may be provided. Further, the rotational positions of the mount member 109 and the projection lens 107 may be adjusted by inserting another adjustment member such as a washer between the mount member 109 and the wall of the prism base 102.

  After the rotation position of the mount member 109 is adjusted, the mount member 109 is bonded to the wall portion of the prism base 102. Thereby, the rotational position of the optical axis 107a of the mount member 109 and the projection lens 107 with respect to the first, second, and third prisms 114, 113, 112 in the XZ cross section can be stably fixed (maintained). .

  Further, as the optical axis 107a of the projection lens 107 is rotated with respect to each prism on the prism base 123, each panel is also moved so that the optical axis 107a is positioned at the center and orthogonal to the optical axis 107a. There is a need. However, when each panel is moved greatly from the position indicated by the dotted line in FIG. 9 to a position indicated by the solid line, a part of the panel is removed from the incident region of the illumination light 110 from the color separation optical system, and as a result, the projected image is missing. May occur.

  In this case, an elongated hole portion (108d) as a guide portion as shown in the lower right part of FIG. 3 in Example 1 and a shaft portion (108e) that can slide parallel to the Y direction are used. A configuration may be used. Then, after adjusting the rotational position of the projection lens 107 in the XZ section, the projection lens 107 is slid in parallel in the Z direction so that the position of each panel does not deviate from the incident area of the illumination light 110. What is necessary is just to adjust the position in the Z direction of 107a.

  Further, instead of the mount adjustment structure shown in FIG. 9, a pedestal adjustment structure that allows the prism pedestal 123 to rotate within the XZ section with respect to the optical axis 107 a of the projection lens 107 is adopted as shown in FIG. 10. Also good. In this case, the prism base 123 is rotated so that the inclination φ of each prism with respect to the optical axis 107a of the projection lens 107 is canceled, that is, the normal line of the outer surface of each prism coincides with the optical axis 107a of the projection lens 107. According to this configuration, the relative relationship (orthogonal relationship) in the XZ cross section between the outer surface of each prism and the optical axis 107a of the projection lens 107 is obtained without the position of each panel deviating from the incident region of the illumination light 110. It can be set appropriately. In the present embodiment, which is a reflective liquid crystal projector, the distance from each panel to the projection lens 107 is longer than that in the first embodiment, which is a transmissive liquid crystal projector, and deviates from the incident area of the illumination light 110 due to the position change of each panel. Cheap. For this reason, the pedestal adjustment structure shown in FIG. 10 is particularly effective in this embodiment.

  Further, as shown in FIG. 11, a shift mechanism 111 as a guide portion for guiding the projection lens 107 so that the optical axis 107a is shifted in the Z direction is provided between the wall portion of the prism base 123 and the mount member 109. It may be provided. In this case, the above-described rotational connection portion is provided between the shift mechanism 111 (that is, the mount member 109) and the wall portion of the prism base 123, and the rotational position of the projection lens 107 within the XZ section is adjusted. Thereafter, the position of each panel in the Z direction may be adjusted using the shift mechanism 111 so that the position of each panel does not deviate from the incident area of the illumination light 110.

  According to the present embodiment, although the configuration is simple, the adjustment of the relative rotational position between each prism and the mount member 109 (that is, the projection lens 107) in the XY and XZ cross sections and the subsequent fixing thereof are performed. It can be done well.

  In each of the above embodiments, the case where a liquid crystal panel is used as the light modulation element has been described. However, other light modulation elements such as a digital micromirror device (DMD) may be used.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

103 to 105, 115 to 117 Liquid crystal panel 101 Dichroic prisms 102 and 123 Prism pedestal 112 Third prism 113 Second prism 114 First prism 107 Projection lens 108b Wedge-type slide (adjustment member)
109 Mount member

Claims (5)

A plurality of light modulation elements;
A combining optical system that combines a plurality of lights modulated by each of the plurality of light modulation elements;
A mount member to which a projection optical system that projects the plurality of lights synthesized by the synthesis optical system onto a projection surface is attached;
A cross section including an optical path of the plurality of lights going from the plurality of light modulation elements to the projection optical system attached to the mount member via the synthesis optical system is defined as a first cross section, and is orthogonal to the first cross section. When the cross section including the optical axis of the projection optical system is the second cross section,
A holding member having a shape that gives a rotation center of the synthetic optical system in adjustment of the rotational position of the synthetic optical system with respect to the mount member in the first section, and to which the adjusted synthetic optical system is fixed And having
An image projection apparatus comprising: an adjustment member used for adjusting a relative rotational position of the holding member and the mount member in the second cross section between the holding member and the mount member. .   The coupling member for providing a rotation center in the adjustment of the relative rotation position in the second cross section of the holding member and the mount member between the holding member and the mount member. The image projection apparatus according to 1.   3. A guide portion for guiding the mount member in a direction in which an optical axis of the projection lens in the second cross section is shifted between the holding member and the mount member. The image projection apparatus described in 1. The synthetic optical system has a plurality of optical film surfaces that transmit and reflect light,
The rotation center given to the composite optical system by the holding member corresponds to a position where the plurality of optical film surfaces or a plurality of planes including each of the plurality of optical film surfaces intersects in the first cross section. The image projection apparatus according to claim 1, wherein the image projection apparatus is characterized in that A plurality of light modulation elements;
A combining optical system that combines a plurality of lights modulated by each of the plurality of light modulation elements;
A mounting member to which a projection optical system for projecting the plurality of lights synthesized by the synthesis optical system onto a projection surface is attached,
A cross section including an optical path of the plurality of lights going from the plurality of light modulation elements to the projection optical system attached to the mount member via the synthesis optical system is defined as a first cross section, and is orthogonal to the first cross section. When the cross section including the optical axis of the projection optical system is the second cross section,
The holding member that holds the synthetic optical system is provided with a shape that gives the synthetic optical system a center of rotation within the first cross section,
Using the rotation center, adjust the rotation position in the first cross section of the synthetic optical system relative to the mount member,
Fixing the synthetic optical system after adjustment of the rotational position to the holding member;
Using the adjustment member disposed between the holding member and the mount member, the relative rotation position of the holding member and the mount member in the second cross section is adjusted,
A method for manufacturing an image projection apparatus, comprising fixing the mount member and the holding member after adjustment of the relative rotational position.