JP3958008B2 - Image display optical system and projection type image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display optical system used in a projection-type image display apparatus that enlarges and projects an image on a screen or the like, and is modulated by a color separation system that decomposes light from a light source into a plurality of color lights and an image display element. The present invention relates to an image display optical system using a prism type optical element for at least one of a color composition system that synthesizes and emits a plurality of color lights.
[0002]
[Prior art]
As an optical system of a projection type image display device such as a liquid crystal projector, white light emitted from a light source is decomposed into three colors of red, green, and blue by a wavelength selective dichroic film (dielectric film) for each color. There is known a three-plate type optical system that modulates by transmitting or reflecting an image display element such as a liquid crystal panel, and synthesizes each modulated color light by a dichroic film and enlarges and projects it onto a screen or the like by a projection lens.
[0003]
Generally, as a means for performing color synthesis, a plurality of prisms deposited with dichroic films are used in combination. These prisms are housed in an optical box in which other optical components are housed. At that time, the prism is bonded to a prism base that is pre-molded with plastic molding or die-cast with aluminum or magnesium, and is attached to the optical box with screws or the like. It is attached. This is because it is necessary to detachably attach the prism base to the optical box.
[0004]
In general, the image display element needs to be adjusted to six axes of rotational positions with respect to the vertical, horizontal, and longitudinal axes and fixed to the focal position of the projection lens. Therefore, the sheet metal is attached separately from the prism base. The panel is fixed to the sheet metal with a UV adhesive or solder, so that it can be attached to and detached from the optical system as a prism unit.
[0005]
FIG. 12 shows the configuration disclosed in Japanese Patent No. 3000097. In this configuration, the prism 503 A sheet metal in the shape of a tower 509-602 Surrounds the LCD panel 504 to 506 And guides for attaching polarizing elements and wave plates, which are indispensable when using them, to sheet metal 606 It is fixed through. There is also an example in which the polarizing plate is directly bonded to the prism.
[0006]
[Problems to be solved by the invention]
However, FIG. In the conventional configuration as shown in FIG. 2, the positioning accuracy of the optical member fixed to the prism is defined by the bending accuracy of the sheet metal and the pasting accuracy of the sheet metal. Therefore, there is a problem that it is difficult to increase the positioning accuracy of the optical member with respect to the prism. In addition, since the number of parts is large, there is a problem that it takes time to assemble.
[0007]
[Means for Solving the Problems]
To solve the above problem, Invention of the present application Then, an image display using a prism type optical element for at least one of a color separation system for separating light from a light source into a plurality of color lights and a color composition system for combining and emitting a plurality of color lights modulated by an image display element Supports prism-type optical elements in optical systems plural To the support member, The Unlike prism-type optical elements Light Holding part to hold the academic material But Integrally formed Cage , The holding portions provided on the plurality of support members hold the optical member sandwiched from a direction perpendicular to the optical axis, and enable rotation adjustment of the held optical member around the optical axis. Characterized by having a shape .
[0008]
In this way, a part for holding other optical members (polarizing plate, wavelength plate, phase plate, optical filter, lens, image display element, etc.) is integrally formed on a support member such as a base that supports the prism type optical element. Thus, the other optical elements can be held with high positional accuracy with respect to the prism type optical element with a small number of parts.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(First Related technology )
FIG. 1 shows the present invention. Embodiment of first related technology 1 shows a configuration of an optical system of a liquid crystal projector (projection-type image display device). Reference numeral 1 denotes a light source, which is composed of, for example, a high-intensity ultra-high pressure lamp or a metal halide lamp. The light beam emitted from the light source 1 is reflected directly or by the reflector 2 and enters the first fly-eye lens 3 which is a group of lens groups arranged in a grid pattern.
[0012]
The light beam divided by the first fly-eye lens 3 is reflected by the reflection mirror 5 and condensed by the second fly-eye lens 4. The condensed light beam is a polarization conversion element. 6 And the polarization direction is Aligned Further, the light is condensed by the condenser lens 7.
[0013]
The light beam collected by the condenser lens 7 is guided to a blue reflecting dichroic mirror 8 that reflects blue frequency band light (hereinafter referred to as blue light), where the blue light is separated. The blue light passes through the concave lens 9 having an effect of shortening the optical path length, is reflected by the reflection mirror 11, passes through the field lens 20 and the incident side polarizing plate 23, and reaches the blue liquid crystal panel 26.
[0014]
The light transmitted through the blue reflecting dichroic mirror 8 is separated into green light and red light by the green reflecting dichroic mirror 12 that reflects green frequency band light (hereinafter referred to as green light). The green light reflected by the green reflecting dichroic mirror 12 passes through the field lens 19 and the incident side polarizing plate 22 and reaches the blue liquid crystal panel 25.
[0015]
Further, the red frequency band light (hereinafter referred to as red light) transmitted through the green reflecting dichroic mirror 12 is freed of unnecessary components by the red transmitting dichroic filter 13, and then the field lens 14, reflecting mirror 15, relay lens 16, Red incident polarizing plate via reflection mirror 17 and field lens 18 21 And then reaches the red liquid crystal panel 24.
[0016]
The light that reaches each liquid crystal panel is modulated by the liquid crystal panel according to an image signal input from an image information supply device such as a personal computer, a video, or a DVD player (not shown), and then transmitted through the liquid crystal panel. Then, the color is synthesized by the cross prism 30 which is transmitted through the exit side polarizing plates 27, 28 and 29 and deposited with a dichroic film. Further, the light emitted from the cross prism 30 is enlarged and projected on a screen (not shown) by the projection lens 31.
[0017]
Reference numeral 32 denotes an optical box (case) that houses the image display optical system from the first fly-eye lens 3 to the cross prism 30.
[0018]
Here, regarding the configuration around the cross prism 30, Using FIG. 3 and FIG. explain. FIG. As shown in FIG. 4, since the liquid crystal panels 24, 25, and 26 for light of each color need to be fixed at the focal position of the projection lens 31, the cross prism 27, the exit side polarizing plates 27, 28, and 29, and the liquid crystal panel 24 are used. , 25 and 26 can be removed from the optical box 32.
[0019]
In FIG. 3, the liquid crystal panels 24, 25, and 26 represented by dotted lines in the drawing are fixed to the focal position of the projection lens 31. In addition, in order to hold the polarizing plates 27, 28, and 29 with respect to the cross prism 30 with high accuracy, a portion (holding portion) that holds the polarizing plates 27, 28, and 29 is provided on the prism base (support member).
[0020]
FIG. As shown in Figure 2, the prism base is the upper and lower base as two parts 39 , 40 are combined to perform the function, and the upper and lower pedestals 39 , 40 are each configured to have a flat surface portion constituting a bottom surface or a ceiling surface and columnar portions extending upward or downward from four corners of the flat surface portion.
[0021]
The holding portions 35 and 36 for holding the polarizing plates 27, 28 and 29 are the upper and lower pedestals of the prism pedestal. 39 , 40 are integrally formed on the columnar portions. The upper and lower pedestals 39 and 40 are fixed to the prism 30 by bonding or the like.
[0022]
Thus, the holding part integrally formed on the prism base 35, 36 The holding portion 36 provided on the lower pedestal 40 holds the lower end corners of the polarizing plates 27, 28, 29, and positions the polarizing plates 27, 28, 29 in the light incident direction and the opposite direction and the vertical direction. I do. In addition, the holding portion provided on the upper base 39 35 Serves as a guide for inserting the polarizing plates 27, 28, and 29 into the holding portion 36 provided on the lower pedestal 40, and holds the upper side in the vicinity of the sides of the polarizing plates 27, 28, and 29, 27, 28 and 29 are positioned in the light incident direction and in the opposite direction.
[0023]
After the polarizing plates 27, 28 and 29 are inserted into the holding portions 35 and 36, these polarizing plates are bonded and fixed to the holding portions 35 and 36. However, the polarizing plate may be fixed to the holding portions 35 and 36 using a sheet metal that separately holds the polarizing plate. Thus, in this embodiment, it becomes a form which can hold | maintain each polarizing plate 27,28,29 stably by combining the upper and lower pedestals 39,40.
[0024]
Although it is possible to provide a holding part that holds the polarizing plate only on one of the upper and lower sides of the prism base, in this embodiment, it is not necessary to take a complicated mold structure when molding by injection molding or die casting. The prism pedestal is divided into upper and lower pedestals 39 and 40 so that it can be completed.
[0025]
In this embodiment, the exit side polarizing plate 27, 28, 29 The Up and down Prism base 39, 40 Holding part 35, 36 However, the present invention is not limited to this. For example, a wavelength plate or phase plate that changes the polarization direction or phase difference, a liquid crystal filter that improves the viewing angle characteristics of the liquid crystal, and the like may be held by the holding unit.
[0026]
In this embodiment, the case of using a cross prism has been described. However, in the present invention, a so-called 4P prism or 3P prism may be used.
[0027]
(Second Related technology )
FIG. 2 shows the present invention. Second related technology 1 shows a configuration of an optical system of a liquid crystal projector (projection type image display apparatus) according to an embodiment. The optical system of this embodiment is Of the first related technology Although it has substantially the same configuration as the optical system of the embodiment, a 4P prism 30A is used as a prism for color synthesis. In the present embodiment, free curved surface mirrors 33 and 34 and a concave mirror 37 are used instead of the relay lens system at the portion facing the optical path of red light on the inner surface of the optical box 32A.
[0028]
In this embodiment, Of the first related technology Constituent elements common to the embodiment include Of the first related technology The same reference numerals as those in the embodiment are given.
[0029]
Of the luminous flux emitted from the light source 1, the red light transmitted through the green reflecting dichroic mirror 12 is reflected by the free-form curved mirror 33, and is a concave mirror provided on the opposite side. 37 The red liquid crystal panel is reflected by the free curved mirror 34 and transmitted through the incident-side polarizing plate 21. 24 To reach.
[0030]
Each color light modulated by each liquid crystal panel 24, 25, 26 is transmitted through the exit side polarizing plates 27, 28, 29 to be 4P prisms. 30A Is incident on. And 4P prism 30A The three colored lights are synthesized by the action of the inner dichroic film, and enlarged and projected on the screen by the projection lens 31.
[0031]
Even in an optical system configured in this way, Of the first related technology The upper and lower prism bases described in the embodiment are used, and the holding parts 35 and 36 integrally formed with the prism bases 39 and 40 are used. Polarizers 27 and 28 Retained.
[0032]
In this embodiment, the exit side polarizing plate 27, 28, 29 Although the case where the prism is held by the holding portion of the prism base has been described, the present invention is not limited to this. For example, a wavelength plate or phase plate that changes the polarization direction or phase difference, a liquid crystal filter that improves the viewing angle characteristics of the liquid crystal, and the like may be held by the holding unit.
[0033]
In this embodiment, the case where the 4P prism is used has been described. However, in the present invention, a so-called cross prism or 3P prism may be used.
[0034]
(Third Related technology )
FIG. 5 shows the present invention. Third related technology The embodiment of is shown. Of the first related technology The holding portions 35 and 36 provided on the prism pedestals 39 and 40 shown in the embodiment are configured to insert optical members such as polarizing plates 27, 28, and 29, but in the present embodiment, the prism pedestals 39, The optical member is held by utilizing the elasticity of the prism base itself when 40 is manufactured by plastic molding.
[0035]
As shown in FIG. 5, claw-shaped holding portions 55 and 56 are integrally formed on the columnar portions of the upper and lower pedestals 52 and 54 of the prism pedestal, and the holding portions 55 and 56 are urged toward the incident surface side of the prism by elasticity. Thus, the polarizing plate 28 is sandwiched and held between the holding portions 55 and 56 and the columnar portion.
[0036]
The lower holding portion 56 has a contact surface with the lower corner portion of the polarizing plate 28 and prevents the polarizing plate 28 from coming out downward. Further, the upper pedestal 52 is integrally formed with a retaining portion 57 that is in contact with the upper end surface of the polarizing plate 28 and prevents upward slipping.
[0037]
When holding the polarizing plate 28, first, the lower portion of the polarizing plate 28 is inserted obliquely between the lower holding portion 56 and the columnar portion, and the polarizing plate 28 is pushed into the prism incident surface side. Thereby, the back surface of the polarizing plate 28 is the slope of the holding portion 55 on the upper side. The Pressing do it The holding portion 55 is elastically deformed and opened, and the polarizing plate 28 is fitted so as to be in close contact with the columnar portion. At this time, the holding portion 55 tries to return to the original state by the elastic force, and the polarizing plate 28 is fixedly held to the prism by the urging force.
[0038]
In the present embodiment, the case where the exit-side polarizing plate 28 is held by the holding portion of the prism base has been described, but the present invention is not limited to this. For example, a wavelength plate or phase plate that changes the polarization direction or phase difference, a liquid crystal filter that improves the viewing angle characteristics of the liquid crystal, and the like may be held by the holding unit.
[0039]
(4th Related technology )
FIG. 6 shows the present invention. 4th related technology An embodiment is shown. 1st to 3rd above Related technology In the embodiment, the case where the holding portion for holding the optical member is integrally formed on the prism base has been described. However, in the present embodiment, the field stop portion (light-shielding portion) is integrally formed on the prism base.
[0040]
In FIG. 6, field stop portions 65 and 66 are integrally formed around the light passage opening facing the entrance surface and the exit surface of the prism 30 in the upper base 62 and the lower base 64 of the prism base.
[0041]
By fixing such prism pedestals (upper and lower pedestals 62 and 64) to the prism 30, the mask shape for blocking the incidence of unnecessary light rays to the prism 30 and the emission of unnecessary light rays from the prism 30 has a prism incident surface and an emission surface. It will be provided close to.
[0042]
Moreover, since the upper and lower pedestals 62 and 64 are manufactured by injection molding of plastic resin, they are slightly expanded by heat. For this reason In view of the linear expansion coefficient of the resin, it is necessary to provide a gap 63 between the ends of the columnar portions of the upper and lower pedestals 62 and 64.
[0043]
Thereby, even when the upper and lower pedestals 62 and 64 are thermally expanded, it is possible to prevent unnecessary stress from being applied to the bonding surface between the prism 30 and the upper and lower pedestals 62 and 64.
[0044]
As shown in FIG. 65, 66 Is formed in a portion outside the effective light flux range L. Therefore, it is possible to prevent a ghost or the like from being generated by light incident on the prism 30 from a portion deviating from the effective light flux.
[0045]
Also, prism base 62, 64 In the field stop 65, 66 By providing a light-blocking member rather than attaching the light-shielding member to the prism base, 65, 66 This is convenient because it can improve the position accuracy and reduce the number of parts.
[0046]
In the present embodiment, the case where the cross prism 30 is used has been described. However, a 4P prism or a 3P prism may be used.
[0047]
(No. 1 Embodiment)
FIG. 8 shows the first aspect of the present invention. 1 An embodiment is shown. In the present embodiment, the upper and lower pedestals 82 and 84 of the prism pedestal are shaped to hold the lenses (field lenses) 87 and 88 like a lens barrel. This embodiment is effective when it is necessary to arrange some lenses of the projection lens in the green, blue, and red optical paths.
[0048]
By disposing lenses having different radii of curvature in the optical paths of the respective color lights, optical aberrations such as lateral chromatic aberration can be removed. In FIG. 8, the blue optical path lens is omitted.
[0049]
Further, on the front surfaces of the lenses 87 and 88, the exit side polarizing plates 27 and 28 are provided. But Glued Yes. Semicircular holding portion 86 provided on lower pedestal 84 And a lens retaining portion 85 having a shape integrally formed with the upper base 82 and abutting on the outer peripheral surface of the lens 87 (see the two-dot chain line in the drawing), the lenses 87 and 88 are Sandwiched from the direction perpendicular to the optical axis AXL and around the optical axis AXL rotation Adjustment Possible hold Has been .
[0050]
Also in this case, as in the fourth embodiment, when the upper and lower pedestals 82 and 84 are molded from resin, there is an influence of linear expansion. It is necessary to make it as a small pedestal.
[0051]
Further, by rotating the lenses 87 and 88 to which the polarizing plates 27 and 28 are bonded, the polarizing plates 27 and 28 on the emission side with respect to the liquid crystal panel are rotated. Polarization axis Therefore, the contrast of the projected image can be further improved.
[0052]
In the present embodiment, the case where the cross prism 30 is used has been described, but a 4P prism or a 3P prism may be used.
[0053]
(No. 2 Embodiment)
FIG. 9 shows the first of the present invention. 2 1 shows a configuration of an optical system of a liquid crystal projector (projection type image display apparatus) according to an embodiment. In the figure, 101 is a light source that emits white light with a continuous spectrum, 102 is a reflector that collects light in a predetermined direction, 103a is a first fly-eye lens in which rectangular lenses are arranged in a matrix, and 103b is the first A second fly-eye lens 104 comprising a lens array corresponding to each lens of the fly-eye lens 104 is a polarization conversion element that aligns unpolarized light with predetermined polarized light.
[0054]
105a is a condenser lens, 105b is a field lens, and 105c is a reflection mirror.
[0055]
106 is a dichroic mirror that transmits light in the blue (B) and red (R) wavelength regions and reflects light in the green (G) wavelength region, and 107 is a part of light in the middle wavelength region between G and R. It is a color filter to cut.
[0056]
Reference numerals 108a and 108b denote a first color selective phase difference plate and a second color selective phase difference plate that change the polarization direction of the B light by 90 degrees and do not change the polarization direction of the R light.
[0057]
Reference numerals 109a and 109b denote a first half-wave plate and a second half-wave plate.
[0058]
110a, 110b, and 110c are a prism-shaped first polarizing beam splitter, a second polarizing beam splitter, and a third polarizing beam splitter that transmit P-polarized light and reflect S-polarized light, respectively.
[0059]
111r, 111g, and 111b are respectively a reflective liquid crystal display element for red, a reflective liquid crystal display element for green, and a reflective liquid crystal display element for blue that reflect incident light and modulate the image to display an image. is there.
[0060]
112r, 112g, and 112b are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. Reference numeral 113 denotes a projection lens.
[0061]
Next, the optical action of this liquid crystal projector will be described. Light emitted from the light source 101 is collected in a predetermined direction by the reflector 102. Here, the reflector 102 has a paraboloid shape, 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 101 is not an ideal point light source but has a finite size, it collects light. Luminous flux Contains many light components that are not parallel to the axis of symmetry of the paraboloid.
[0062]
These condensed light beams are incident on the first fly-eye lens 103a. The first fly-eye lens 103a is configured by combining lenses having a positive refractive power having a rectangular outer shape in a matrix, and the incident light beam is divided into a plurality of light beams corresponding to the respective lenses, and is condensed. A plurality of light source images in a matrix through the second fly-eye lens 103b, and a polarization conversion element 104 It forms in the vicinity of.
[0063]
The polarization conversion element 104 includes a polarization separation surface, a reflection surface, and a half-wave plate. A plurality of light beams condensed in a matrix form is incident on a polarization separation surface corresponding to the column, and is split into transmitted P-polarized component light and reflected S-polarized component light.
[0064]
The reflected light of the S polarization component is reflected by the reflecting surface and is emitted in the same direction as the P polarization component. On the other hand, the transmitted P-polarized light component is transmitted through the half-wave plate and converted to the same polarized light component as the S-polarized light component. (The line marked with “•” in FIG. 9, hereinafter (•)) Is emitted as a uniform light.
[0065]
The plurality of light beams that have undergone polarization conversion are condensed in the vicinity of the polarization conversion element 104 and then reach the condensing optical system as divergent light beams. The condensing optical system includes a condenser lens 105a and a field lens 105b, and these light beams overlap at a position where a rectangular image of each fly eye lens can be formed by a condensing function, thereby forming a rectangular uniform illumination area. Form.
[0066]
Further, in the optical path from the field lens 105b to the reflective liquid crystal display elements 111r, 111g, 111b, the light condensed on the reflective liquid crystal display element is set to be substantially telecentric with respect to the optical axis of the condensing optical system. Therefore, the characteristic variation due to the incident angle generated in the optical thin films of the dichroic mirror 106 and the polarization beam splitters 110a and 110b does not appear as an image on the reflective liquid crystal display element.
[0067]
The dichroic mirror 106 has characteristics of transmitting B and R light and reflecting G light.
[0068]
In FIG. 9, the light that has been S-polarized light in the polarization conversion element 104 is also S-polarized light (·) for the dichroic mirror 106.
[0069]
In the G optical path, the light reflected by the dichroic mirror 106 enters the color filter 107. The color filter 107 is a dichroic filter that reflects yellow color light in the middle wavelength region between G and R, and has a function of removing yellow light from green light. This is because if the green light has many yellow color components, the green becomes yellowish green, and therefore it is desirable to remove the yellow light in terms of color reproduction.
[0070]
Note that a color filter 107 having a characteristic of absorbing yellow light may be used.
[0071]
The light whose color has been adjusted in this way enters the first polarizing beam splitter 110a as S-polarized light (·), is reflected by the polarization separation surface, and reaches the reflection liquid crystal display element 111g for G. In the reflective liquid crystal display element 111g for G, the G light is image-modulated and reflected. The S-polarized component (·) of the modulated reflected light of G is reflected again by the polarization separation surface, returned to the light source side, and removed from the projection light.
[0072]
P-polarized component of modulated reflected G light (Lines marked with “|”, hereinafter referred to as (|)) Passes through the polarization separation surface and becomes projection light. At this time, in a state where all the polarization components are converted to S-polarized light (a state where black is displayed), a quarter-wave plate provided between the first polarizing beam splitter 110a and the reflective liquid crystal display element 111g for G The slow axis of 112g is adjusted in a predetermined direction to suppress the influence of the disturbance of the polarization state generated in the first polarization beam splitter 110a and the reflective liquid crystal display element 111g for G.
[0073]
The light (|) transmitted through the first polarization beam splitter 110a is rotated by 90 degrees in the polarization direction by the first half-wave plate 109a whose slow axis is set at 45 degrees with respect to the polarization direction. 3 enters the polarizing beam splitter 110 c as S-polarized light (·), is reflected by the polarization separation surface, and reaches the projection lens 13.
[0074]
Here, if the slow axis of the first half-wave plate 109a can be rotationally adjusted, the polarization direction of the G light incident on the polarization separation surface of the third polarization beam splitter 110c can be adjusted. Can do. When there is a relative inclination between the polarization separation surface of the first polarization beam splitter 110a and the polarization separation surface of the third polarization beam splitter 110c due to an attachment error or the like, the third polarization beam is adjusted by this adjustment mechanism. The leakage of non-projection light in the splitter 110c can be minimized, and image adjustment for black display in G is possible.
[0075]
The R and B lights transmitted through the dichroic mirror 106 are incident on the first color-selective phase difference plate 108a. The first color-selective retardation plate 108a has a function of rotating only the B light by 90 degrees in the polarization direction, so that the B light becomes P-polarized light (|) and the R light becomes S-polarized light (. ) Enters the second polarization beam splitter 110b. For this reason, in the second polarization beam splitter 110b, the B light passes through the polarization separation surface and reaches the B reflective liquid crystal display element 111b, and the R light is reflected by the polarization separation surface and reflected by the R reflection type. It reaches the liquid crystal display element 111r.
[0076]
In the reflective liquid crystal display element 111b for B, the B light is image-modulated and reflected. The P-polarized light component (|) of the modulated reflected light of B is transmitted again through the polarization separation surface, returned to the light source side, and removed from the projection light. The S-polarized component (•) of the modulated reflected light of B is reflected by the polarization separation surface and becomes projection light.
[0077]
Similarly, in the reflective liquid crystal display element 111r for R, R light is image-modulated and reflected. The S-polarized component (•) of the modulated reflected light of R is reflected again on the polarization separation surface, returned to the light source side, and removed from the projection light. P-polarized component of modulated reflected R light (Dash-dot line with “|” attached) Passes through the polarization separation surface and becomes projection light. Thereby, the projection light of B and R is combined into one light beam.
[0078]
At this time, the slow axes of the quarter-wave plates 112r and 112b provided between the second polarizing beam splitter 110b and the reflective liquid crystal display elements 111r and 111b for R and B are adjusted to adjust G. As in the case, the black display of R and B is adjusted.
[0079]
The combined R and B projection light is incident on the second color selective phase difference plate 108b. The second color selective phase difference plate 108b is the same as the first color selective phase difference plate 108a and rotates only the polarization direction of B by 90 degrees. As a result, both the R and B lights are incident on the third polarization beam splitter 110c as P-polarized light (|), and are combined with the G projection light by passing through the polarization separation surface.
[0080]
Here, the second half-wave plate 109b is disposed between the second color-selective retardation plate 108b and the third polarizing beam splitter 110c, and the second half-wave plate 109b is delayed. After arranging in the same direction as the polarization direction that transmits the phase axis (direction in which the polarization state is not converted), the inclination of the slow axis of the second half-wave plate 109b is adjusted in the same manner as in G. Thus, the polarization directions of the R and B lights are adjusted so as to be appropriately incident on the polarization separation surface of the third polarization beam splitter 110c, and the leakage of non-projection light in the third polarization beam splitter 110c is minimized. This makes it possible to adjust the image of black display in R and B.
[0081]
The combined RGB projection light is projected onto a screen or the like by the projection lens 113.
[0082]
In this embodiment, an antireflection coating is applied to the boundary surface between each optical element and air, and a wavelength band in which the reflectance is most reduced is set to the vicinity of 550 nm on the surface through which only G light is transmitted. However, an anti-reflection coating in which the wavelength band where the reflectance decreases most is set to the vicinity of 610 nm on the surface where only the R light is transmitted, and the wavelength band where the reflectance is decreased most is the surface where only the B light is transmitted. Each is provided with an antireflection coating set in the vicinity of 450 nm. Further, the surface through which R and B light is transmitted is provided with an antireflection coating such that there are two wavelength bands in the vicinity of 450 nm and 610 nm where the reflectance decreases.
[0083]
The Fno of the projection lens 13 is set to be brighter than the Fno of the illumination system in consideration of the deviation between the optical axis of the projection lens 113 and the optical axis of the condensing optical system due to diffraction and attachment errors in the reflective liquid crystal display element.
[0084]
In the present embodiment, as shown in FIG. 10A, quarter wavelength plates 112r and 112b are attached to prism pedestals (support members) 160 and 161 that hold the second polarizing beam splitter 110b. It has a shape that is sandwiched from the direction perpendicular to the optical axis AXL of the four-wavelength plates 112r and 112b and that can be rotatably adjusted around the optical axis AXL. Holding part Are integrally formed.
[0085]
As shown in FIG. 10B, half-wave plates 109a and 109b are attached to prism bases (support members) 162 and 163 that hold the third polarizing beam splitter 110c, and the half-wave plate 109a. , 109b from the direction perpendicular to the optical axis AXL, and has a shape that can be rotatably adjusted around the optical axis AXL Holding part Are integrally formed.
[0086]
Although not shown, the prism base (supporting member) that holds the first polarizing beam splitter 110a is also integrally formed with a portion that holds the quarter-wave plate 112g in a rotatable manner.
[0087]
Contrast is improved by rotating and adjusting the half-wave plate and quarter-wave plate held on each prism base and rotating the slow axis, which is the crystal axis, with respect to the transmitted light beam of the polarizing plate. Can be made.
[0088]
The prism pedestal adheres and fixes the polarizing beam splitter, but the prism pedestal may be made of polycarbonate or aluminum die cast. Similarly, in order to fix and support the color selective phase difference plates 108a and 108b and the color filter 107 with high accuracy with respect to the prism, these holding portions may be integrally formed on the prism base.
[0089]
Further, the three polarization beam splitters 110a, 110b, and 110c may be collectively held with respect to one prism base. In this case, a half-wave plate, a quarter-wave plate, The portion that holds the color selective phase difference plate and the color filter may be formed integrally.
[0090]
(No. 5 related technologies )
FIG. 11 shows the present invention. Of the fifth related technology 1 shows a peripheral configuration of a color separation system or a color composition system in a liquid crystal projector (projection type image display device) according to an embodiment.
[0091]
In FIG. 11A, a prism (cross prism, polarization beam splitter, etc.) 202 is positioned on a positioning portion (not shown) of the upper base 201 and the lower base 203, and the upper base 201 and the lower base 203 are placed on the prism 202. Are bonded with an adhesive (such as an ultraviolet curable adhesive or an epoxy adhesive).
[0092]
The upper pedestal 201 and the lower pedestal 203 are integrally formed with holding pin-shaped portions 201a and 203a for holding a liquid crystal panel (image display element) 204. The lower pedestal 203 is attached to an illumination optical box. A positioning mechanism portion and an attachment portion (not shown) are formed.
[0093]
On the other hand, the liquid crystal panel 204 is formed with holes 204a for inserting the holding pin-shaped portions 201a and 203a. Although not shown in the drawing, the holding pin shape portion and the hole portion on the liquid crystal panel side are similarly formed to hold the liquid crystal panels for green, blue, and red colors.
[0094]
In FIG. 11B, the liquid crystal panel 204 is screwed to the sheet metal 205, and the holding pin shape parts 201 a and 203 a formed integrally with the upper base 201 and the lower base 203 are inserted into the hole 205 a formed in the sheet metal 205. It is inserted. Thereby, in a state where the sheet metal 205 is fixed to the prism base, the position of the liquid crystal panel 204 with respect to the prism 202 can be adjusted by loosening the screw fixing the liquid crystal panel 204 to the sheet metal 205.
[0095]
In FIGS. 11C and 11D, the prism 207 held by the prism base (upper base 206 and lower base 208) is not a cross prism or the like shown in FIGS. The figure shows a case of an irregular shaped 4P prism or 3P prism joined with a prism.
[0096]
Also in this case, the holding pin-shaped portions 206a and 208a are integrally formed on the upper pedestal 201 and the lower pedestal 203, and a positioning mechanism portion and attachment portions 210 and 211 for attaching to the illumination optical box are formed on the lower pedestal 208.
[0097]
On the other hand, a hole 204a or 205a for inserting the holding pin-shaped portions 206a and 208a is formed in the liquid crystal panel 204 or a sheet metal 205 that is held by screws.
[0098]
11A to 11D, the holding pin-shaped portion of the prism base is inserted into the hole portion 204a of the liquid crystal panel 204 or the hole portion 205a of the sheet metal 205, and the liquid crystal panel 204 is prism-shaped by a jig (not shown). Position with respect to. In this state, an ultraviolet curable adhesive is applied around the hole portion and the holding pin shape portion, and the adhesive is cured by irradiating ultraviolet rays.
[0099]
Thereby, the liquid crystal panel 204 is positioned and fixed with respect to the prism.
[0100]
【The invention's effect】
As explained above, Invention of the present application According to the above, such as a pedestal that supports the prism type optical element plural For supporting member The optical member can be rotated around the optical axis by sandwiching the optical member from the direction perpendicular to the optical axis. Since the part to be held is integrally formed, the number of parts The optical member can be rotated and adjusted. It can be held with high positional accuracy with respect to the prism type optical element.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention. Related technology It is a figure which shows the optical system of the liquid crystal projector which is embodiment.
FIG. 2 above Related technology It is a disassembled perspective view of the prism and prism base used in the liquid crystal projector of an embodiment.
FIG. 3 above Related technology It is a perspective view of the prism and prism base used in the liquid crystal projector of the embodiment.
FIG. 4 shows the second of the present invention. Related technology It is a figure which shows the optical system of the liquid crystal projector which is embodiment.
FIG. 5 shows the third of the present invention. Related technology It is a perspective view of the prism used for the liquid crystal projector which is an embodiment, and a prism base.
FIG. 6 shows the fourth of the present invention. Related technology It is a perspective view of the prism used for the liquid crystal projector which is an embodiment, and a prism base.
FIG. 7 above Related technology It is sectional drawing of the prism and prism base in embodiment.
FIG. 8 shows the first of the present invention. 1 It is a perspective view of the prism used for the liquid crystal projector which is an embodiment, and a prism base.
FIG. 9 shows the first of the present invention. 2 It is a figure which shows the optical system of the liquid crystal projector which is embodiment.
FIG. 10 above 2 It is a perspective view of the prism base used for the liquid crystal projector of an embodiment.
FIG. 11 shows the first of the present invention. 5 related technologies It is a perspective view of the prism base used for the liquid crystal projector which is this embodiment.
FIG. 12 is an exploded perspective view showing a prism and a prism base in a conventional liquid crystal projector.

Claims (3)

An image display optical system using a prism type optical element in at least one of a color separation system for separating light from a light source into a plurality of color lights and a color composition system for combining and emitting a plurality of color lights modulated by an image display element Because
A plurality of support members for supporting the prismatic optical element, the holding portion for holding the optical engine member that is different from the said prismatic optical element is integrally formed,
The holding portions provided on the plurality of support members hold the optical member in a direction perpendicular to the optical axis of the optical member, and adjust the rotation of the held optical member around the optical axis. An image display optical system characterized by having a shape that enables the above . Before Symbol light faculty member is a polarizing plate, a wavelength plate, a phase plate, optical filter, lens, image display optical system according to claim 1, characterized in that either of the image display device. 3. A projection type image display apparatus comprising: the image display optical system according to claim 1; and a projection optical system that projects light emitted from the color synthesis system onto a projection surface.

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