JP4045005B2 - Color image projector - Google Patents

Description

【００５０】
〔第４面（*r4）の非球面係数〕
ε＝ ０．０１６４０４３７
Ａ＝ ０．９２６５２７×１０^-5
Ｂ＝−０．１４３５７２×１０^-7
Ｃ＝ ０．５３１０５９×１０^-10
Ｄ＝−０．７１５９７９×１０^-13
【００５１】

この式において、
ｒ＝（ｙ²＋ｚ²）^1/2
ε：２次曲面パラメータ
ｃ：曲率（曲率半径ｃｒの逆数）
【００５２】
〔反射型ＬＣＤパネルの大きさ〕
長辺：３５．８４mm
短辺（Ｈの値）：２１．５mm
【００５３】
〔投影光学系の焦点距離（ｆ）〕
２８．６mm
｛（ｙ／ｔａｎθ）／ｆ＝３．５３となるので条件式３を満たす｝
【００５４】
〔第１３面（r13）の平行偏心〕
１３．９０７９００mm（ｙ軸方向に）
（１３．９０７９００＝０．６４７Ｈとなるので条件式２′を満たす）
【００５５】
〔像面（r15）の傾き偏心〕
５.３４１０８９゜
（条件式４を満たす）
【００５６】
〔ダイクロイックコート面の軸上主光線となす角度〕
７ｄ面：２７．９゜（条件式１′を満たす）
７ｅ面：３２．１゜（条件式１を満たす）
【００５７】
上記実施形態においては、色分解合成手段として上記図２に示した色分解合成プリズム７を用いたが、これ以外の構成のものでも本発明を達成できる。以下、第２〜第４の実施形態として色分解合成手段の他の例を示す。
【００５８】
〈第２の実施形態〉
図５は、本実施形態の色分解合成手段とそれに対応させて配置したコンデンサーレンズ８、９、１０と反射型ＬＣＤパネル１１、１２、１３を含む図２に対応する図である。色分解合成手段として、２つの６面体プリズム７２ａ、７２ｃと１つの５面体プリズム７２ｂの３つのプリズム７２ａ、７２ｂ、７２ｃからなる色分解合成プリズム７２が用いられる。２つのプリズム７２ｂ、７２ｃは、プリズム７２ｂとプリズム７２ｃにより接合面７２ｅが形成されるように接合されている。プリズム７２ａ、７２ｂは、わずかな空気の層をおいて配置されている。隔たれたプリズム面のうち、プリズム７２ａ側を面７２ｄ、プリズム７２ｂ側を面７２ｇとする。
【００５９】
面７２ｄには、Ｂの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着され、接合面７２ｅには、Ｒの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着されている。面７２ｄ、接合面７２ｅの軸上主光線となす角度はそれぞれ２７．９゜、１２．４゜でともに条件式１′を満たす。
【００６０】
面７２ｆから入射した照明光のうちＢの光束は面７２ｄで反射され、面７２ｆで全反射されたのち対応する反射型ＬＣＤパネル１１に入射する。Ｒの光束は接合面７２ｅで反射され、面７２ｇで全反射されたのち対応する反射型ＬＣＤパネル１３に入射する。Ｇの光束は色分解合成プリズム７２の全ての面を透過して対応する反射型ＬＣＤパネル１２に入射する。投影光については照明光の逆をたどれば説明がつくので、説明を省略する。
【００６１】
〈第３の実施形態〉
図６は、本実施形態の色分解合成手段とそれに対応させて配置したコンデンサーレンズ８、９、１０と反射型ＬＣＤパネル１１、１２、１３を含む図２に対応する図である。色分解合成手段として、２つの６面体プリズム７３ａ、７３ｄと２つの５面体プリズム７３ｂ、７３ｃの４つのプリズム７３ａ、７３ｂ、７３ｃ、７３ｄからなる色分解合成プリズム７３が用いられる。４つのプリズム７３ａ、７３ｂ、７３ｃ、７３ｄは、プリズム７３ａとプリズム７３ｂにより接合面７３ｅが、プリズム７３ｃとプリズム７３ｄにより接合面７３ｆが形成されるように接合されている。プリズム７３ｂとプリズム７３ｃは、わずかな空気の層をおいて配置されている。隔たれたプリズム面のうち、プリズム７３ｃ側の面を面７３ｇとする。
【００６２】
接合面７３ｅには、Ｂの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着され、接合面７３ｆには、Ｒの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着されている。接合面７３ｅ、接合面７３ｆの軸上主光線となす角度はそれぞれ２７．９゜、２７．９゜でともに条件式１′を満たす。
【００６３】
面７３ｈから入射した照明光のうちＢの光束は接合面７３ｅで反射され、面７３ｈで全反射されたのち対応する反射型ＬＣＤパネル１１に入射する。Ｒの光束は接合面７３ｆで反射され、面７３ｇで全反射されたのち対応する反射型ＬＣＤパネル１３に入射する。Ｇの光束は色分解合成プリズム７３の全ての面を透過して対応する反射型ＬＣＤパネル１２に入射する。投影光については照明光の逆をたどれば説明がつくので、説明を省略する。
【００６４】
〈第４の実施形態〉
図７は、本実施形態の色分解合成手段とそれに対応させて配置したコンデンサーレンズ８、９、１０と反射型ＬＣＤパネル１１、１２、１３を含む図２に対応する図である。色分解合成手段は、２つのダイクロイックミラー７４ａ、７４ｂからなる色分解合成ミラー７４である。２つのダイクロイックミラー７４ａ、７４ｂの照明光の入射する面にはダイクロイック多層膜が蒸着されている。
【００６５】
ダイクロイックミラー７４ａには、Ｂの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着され、ダイクロイックミラー７４ｂには、Ｒの光束のみを反射しその他の色の光束を透過するダイクロイック多層膜が蒸着されている。ダイクロイックミラー７４ａ、７４ｂの軸上主光線となす角度はそれぞれ３０゜、３０゜でともに条件式１′を満たす。
【００６６】
照明光のうちＢの光束はダイクロイックミラー７４ａで反射され、対応する反射型ＬＣＤパネル１１に入射する。Ｒの光束はダイクロイックミラー７４ｂで反射され、対応する反射型ＬＣＤパネル１３に入射する。Ｇの光束は２つのダイクロイックミラー７４ａ、７４ｂを透過して対応する反射型ＬＣＤパネル１２に入射する。投影光については照明光の逆をたどれば説明がつくので、説明を省略する。
【００６７】
【発明の効果】
本発明のカラー画像投影装置によると、照明光と投影光が異なった角度で入射反射を行うので、照明光と投影光を分離するための偏光分離プリズム等が必要なく、また投影光学系も非テレセントリック光学系であるために少ないレンズ枚数で実現することが可能となっている。従って、装置全体の大きさをコンパクトにでき、かつ光学部品及びそれを保持する部品の点数を大幅に削減できるので安価な構成を達成できる。
【００６８】
また、本発明では、ダイクロイックコート面への照明光の入射角度が３５゜以下になる構成としたので、色むらのない良質が画像を表示することが可能となる。
【図面の簡単な説明】
【図１】 本発明の第１の実施形態のカラー画像投影装置の垂直断面図。
【図２】 本発明の第１の実施形態のカラー画像投影装置の水平断面図。
【図３】 コンデンサーレンズ及び反射型ＬＣＤパネルの光路イメージ図。
【図４】 第１の実施形態における投影光学系の収差図。
【図５】 第２の実施形態の色分解合成プリズムの構成を示す水平断面図。
【図６】 第３の実施形態の色分解合成プリズムの構成を示す水平断面図。
【図７】 第４の実施形態の色分解合成ミラーの構成を示す水平断面図。
【図８】 従来例のカラー画像投影装置の水平断面図。
【符号の説明】
１ 光源
２ リフレクター
４ 第１のレンズアレイ
５ 偏光分離プリズム
６ 第２のレンズアレイ
７、７２、７３ 色分解合成プリズム
８、９、１０ コンデンサーレンズ
１１、１２、１３ 反射型ＬＣＤパネル
１４ 投影光学系
７４ 色分解合成ミラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compact color image projection apparatus that synthesizes and projects a plurality of optical images composed of light of different colors.
[0002]
[Prior art]
Recently, a reflective LCD having higher efficiency than a transmissive LCD (liquid crystal display) has attracted attention. The reflective LCD emits specularly reflected projection light having a substantially same reflection angle as the incident angle of the illumination light incident from the surface of the reflective LCD.
[0003]
As a display optical system using this reflective LCD, conventionally, the reflective LCD is illuminated from a substantially vertical direction so that projection light is emitted in the vertical direction, and this projected light displays an image through the projection optical system. What has been configured to form has been proposed. FIG. 8 shows a specific example (conventional example 1) of this optical system.
[0004]
FIG. 8 is a horizontal sectional view of the optical system. In the figure, 51 is a light source, 52 is connected to the light source 51 and reflects and collects light from the light source 51, and 54 is disposed in the front part of the reflector 52, so that a reflective LCD described later can be efficiently used. Illumination optical system for uniform illumination, 55 and 56 are dichroic mirrors that reflect only light of a specific color and transmit light of the remaining colors, 57, 58, and 59 are polarization beam splitters, 60, 61, and 62 Are reflective LCD panels that form red (R), green (G), and blue (B) optical images, 63 is a cross dichroic prism, and 64 is a projection optical system.
[0005]
The illumination light from the light source 51 and the reflector 52 that reflects the light from the light source 51 passes through the illumination optical system 53, the B light is reflected by the dichroic mirror 55, and the G light is reflected by the dichroic mirror 56. Separated into three colors of light. The separated R, G, and B light enters the polarization beam splitters 57, 58, and 59, respectively. Here, only the S-polarized light beam is reflected and the reflected light is perpendicular to the reflective LCD panels 60, 61, and 62. Incident.
[0006]
The vertically incident illumination light is selectively converted into P-polarized light for each pixel by the reflective LCD panels 60, 61, 62 and is regularly reflected. The projection light that has been specularly reflected vertically by the reflective LCD panels 60, 61, 62 is transmitted without being reflected by the polarization beam splitters 57, 58, 59, and enters the cross dichroic prism 63. The projection light of the three colors is synthesized by the cross dichroic prism 63 and imaged on the screen by the projection optical system 64.
[0007]
Japanese Patent Laid-Open No. 63-292892 proposes an optical system (conventional example 2) in which illumination light that is not perpendicular to the reflective LCD is incident. In the optical system of this publication, a Fresnel lens is disposed in the vicinity of the reflective LCD. With this Fresnel lens, the incident angle of illumination light and the reflection angle of projection light in the reflective LCD are made different depending on the area of the panel.
[0008]
[Problems to be solved by the invention]
The reflective LCD has regular reflection characteristics. For this reason, as in the conventional example 1, when the illumination light is vertically incident on the reflective LCD panels 60, 61, 62, it is reflected vertically to form projection light. It will follow almost the same optical path with the traveling direction reversed. Therefore, it is necessary to dispose the polarization separation prisms 57, 58, and 59 for separating the optical path of the illumination light and the optical path of the projection light, which leads to an increase in cost due to a large glass block and multilayer thin film processing.
[0009]
Further, since the dichroic prism 63 for synthesizing the projection lights of the three colors is also required, as a result, it is necessary to insert two prisms 63, 58 (or 57 or 59) into the lens back. The length of the back became very long. When the length of the lens back is increased, the burden on the projection optical system is increased such that the number of lenses is increased by that amount and aberration correction is difficult.
[0010]
In addition, the projection optical system 64 must be a telecentric optical system in order to match the regular reflection characteristics of the reflective LCD panels 60, 61, and 62, and the number of lenses increases and aberration correction is difficult to achieve the telecentric optical system. Or In combination with the above reason, if a telecentric optical system is to have a long lens back, a very large number of lenses are required, and the optical system becomes large.
[0011]
In order to be able to separate illumination light and projection light with a simple configuration without using a polarization beam splitter or the like, the reflective LCD may be illuminated from an oblique direction. If it does in this way, the optical path of illumination light and projection light will differ. However, in this case, the projection light is also emitted in an oblique direction due to the regular reflection characteristics. It is very difficult to construct a projection optical system that forms a good image conjugate with a reflective LCD for projection light emitted in an oblique direction.
[0012]
In Conventional Example 2, color separation / synthesis is performed by a cross dichroic prism. However, since the pupil of the projection optical system is close and far away from telecentricity, the incident angle on the cross dichroic surface is large and off-axis light flux Since the angle of the luminous flux on the axis is greatly different, sufficient color separation cannot be performed, and a loss of light amount and uneven color on the projection surface occur.
[0013]
As described above, if a cross dichroic prism is used in an optical system largely deviated from the telecentric optical system, it is not preferable because color unevenness generated due to the angular dependence of incident light on the dichroic surface cannot be removed. Further, in order to form a good image, the configurations of the projection optical system and the illumination optical system are important. However, in the conventional example 2, these specific configurations are not shown.
[0014]
In view of the above problems, the present invention provides a compact and low-cost color image projection apparatus that does not use a member for separating illumination light and projection light and reduces color unevenness on the projection surface. For the purpose.
[0015]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention is divided into a plurality of pixels.Having a reflective liquid crystal display panelA plurality of display means having the same configuration, an illumination optical system for forming illumination light to be given to the display means, and the display corresponding to each color light by decomposing the illumination light from the illumination optical system into light of a plurality of colors And a color separation / combination means for combining the projection lights of a plurality of colors formed by the plurality of display means, and a projection for projecting the projection light combined by the color separation / synthesis means to form an image on a projection plane. In a color image projection apparatus having an optical system, illumination light is reflected from the color separation / synthesis unit.liquid crystalIllumination light and projection light are separated by emitting light obliquely to the display panel, and the color separation / synthesis means and the reflection typeliquid crystalBetween the display panelA reflection angle conversion optical system, and the reflection angle conversion optical system includes an angle formed by illumination light incident on the reflection angle conversion optical system with respect to a normal line of the reflective liquid crystal display panel, and the reflection angle conversion optical system. The angle formed by the projection light emitted from the system with respect to the normal line of the reflective liquid crystal display panel differs depending on the area of the corresponding reflective liquid crystal display panel, and at the center of the reflective liquid crystal display panel, The angle formed with respect to the normal line of the reflection type liquid crystal display panel of the illumination light incident on the reflection angle conversion optical system is the normal line of the reflection type liquid crystal display panel of the projection light emitted from the reflection angle conversion optical system. It ’s bigger than the angle it makes,The color separation / synthesis unit includes a plurality of dichroic coating surfaces that reflect only light of a specific color and transmit light of the remaining colors, and the dichroic coating surfaceNormalAnd the optical axis of the projection optical system is 35 ° or less, the focal length of the projection optical system is f, the image height of the off-axis light beam on the reflective display panel is y, and the projection optical system If the angle formed by the principal ray of the most off-axis ray and the axial principal ray of the projection light incident on is θ,
2 <(Y / tan θ)/ F <10, a plane including the optical axis of the illumination optical system and the projection optical system;Plane containing the axial principal ray of the projection light of each colorAnd are orthogonal to each other.
[0016]
AntiThe angle conversion optical system includes, for example, a plurality of each of the reflection typesliquid crystalIt can be composed of a condenser lens arranged in the vicinity of the display panel. The optical axis of the condenser lens is a corresponding reflective typeliquid crystalOf the projection light emitted from the display panel, the reflection type is decentered with respect to the optical path before synthesis of the projection light having the optical axis of the projection optical system as an optical path after synthesis,liquid crystalWhen the image height of the display panel is H, the optical axis of the condenser lens is decentered in parallel from 0.3H to 2.0H. The color separation / combination means can be constituted by, for example, a color separation / synthesis prism or a color separation / synthesis mirror. Reflective typeliquid crystalThe display panel corresponds to correct the inclination of the image plane by the reflection angle conversion optical system.ReflectiveOf the projection light emitted from the liquid crystal display panel, it is preferable that the light is tilted from the vertical with respect to the optical path before synthesis of the projection light having the optical axis of the projection optical system as the optical path after synthesis. The tilt angle of the reflective display panel preferably satisfies the conditional expression: 2 ° <| tilt angle | <8 °.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a vertical sectional view including an optical axis of a projection optical system of a color image projector according to an embodiment of the present invention. FIG. 2 is a horizontal sectional view including the optical axis of the projection optical system. 1 is a light source, 2 is arranged so as to surround the light source 1, and is a reflector having a parabolic shape, for example, that makes light from the light source 1 substantially parallel, and 3 is an unnecessary wavelength range of light incident from the light source 1 and the reflector 2. It is an IR-UV cut filter that cuts.
[0018]
Reference numeral 4 denotes a first lens array in which a plurality of lens cells 4a are arranged in a matrix. The first lens array 4 is arranged at a position having a conjugate relationship with the reflective LED panel by the optical action of a second lens array and a condenser lens described later. Reference numeral 5 denotes a polarization separation prism having a dichroic mirror surface 5a that reflects only the S-polarized light beam and a total reflection mirror surface 5b.
[0019]
Reference numeral 6 denotes a second lens array in which a plurality of lens cells 6a are arranged in a matrix. The second lens array 6 is provided at a position that is conjugate with the light source 1 by the optical action of the first lens array 4 and the reflector 2. The density of the lens cells 6 a of the second lens array 6 is doubled in the lateral direction as compared with the first lens array 4.
[0020]
Although not shown, a half-wave plate for converting the P-polarized light beam into the S-polarized light beam is provided on the incident surface of the lens cell 6a corresponding to the P-polarized light beam of the second lens array 6. As a result, all the light emitted from the second lens array 6 becomes S-polarized light.
[0021]
Reference numeral 7 denotes a color separation / synthesis prism formed of three hexahedral prisms 7a, 7b, and 7c. The three prisms 7a, 7b, and 7c are joined such that a joining surface 7d is formed by the prism 7a and the prism 7b, and a joining surface 7e is formed by the prism 7b and the prism 7c. Details of the angle of each surface will be described later.
[0022]
A dichroic multilayer film that reflects light having a wavelength (B) of about 510 nm or less of visible light and transmits light beams of other wavelengths is deposited (dichroic coating) on the bonding surface 7d, and the bonding surface 7e A dichroic multilayer film that reflects light having a wavelength (R) of about 580 nm or more out of visible light and transmits light beams having other wavelengths is deposited.
[0023]
Reference numerals 8, 9, and 10 denote decentered condenser lenses. Reference numerals 11, 12, and 13 denote rectangular reflective LCD panels that convert R, G, and B electrical images into optical images, respectively. Taking the reflective LCD panel 12 as an example, the arrow 20 is the short side direction and the arrow 21 is the long side direction. When the plane including the optical axis of the illumination optical system and the optical axis of the projection optical system and the short side direction 20 of the reflective LCD panels 11, 12, 13 are parallel, the separation angle between the illumination light and the projection light can be reduced. preferable. On the other hand, if it is parallel to the long side direction 21, it is necessary to increase the power of the decentered condenser lenses 8, 9, and 10 in order to increase the separation angle, which makes it difficult to correct the aberration of the projection optical system, which is not preferable.
[0024]
Each reflective LCD panel 11, 12, 13 reflects incident light with or without rotating the polarization plane selectively for each pixel. Then, only the P-polarized light component of the light rotated by the polarizing plate (not shown) is transmitted to form projection light. A projection optical system 14 is a non-telecentric optical system that forms an image of projection light from the prism 7 on a screen (not shown). A diaphragm 15 is provided in the projection optical system 14.
[0025]
In the above configuration, the illumination optical system in the claims 1 to 6 is the same as in the claims, the configuration of 7 is the same color separation / combination means, the configuration of 8 to 10 is also the reflection angle conversion optical system, and The structure and the polarizing plate (not shown) are also used as display means.
[0026]
In the above configuration, a part of the randomly polarized light beam radiated from the light source 1 is reflected directly from the light source 1 and the rest is reflected from the reflector 2, and unnecessary components are cut by the IR-UV cut filter 3. The light enters the lens array 4. In the first lens array 4, the light is separated into a plurality of light beams, is incident on the polarization splitting prism 5, is reflected by the dichroic surface 5 a, is reflected by the S-polarized light, and is reflected by the total reflection surface 5 b. To be separated. S-polarized light is directly incident on the second lens array 6, and P-polarized light is polarized to S-polarized light by a half-wave plate (not shown) on the incident surface, and then incident on the second lens array 6 to form a light source image. Is done.
[0027]
Using this light source image as a secondary light source, a plurality of light beams are emitted from the second lens array 6 and incident on the surface 7f of the color separation / combination prism 7 obliquely from above. The light beam incident on the prism 7 is reflected by the joint surface 7d with the B light beam, the R light beam is reflected by the joint surface 7e, and the remaining G light beam is applied to the reflective LCD panel 12 via the condenser lens 9. . The B light beam reflected by the joint surface 7d has a large incident angle on the surface 7f, and therefore undergoes total reflection here and is given to the reflective LCD panel 11 via the condenser lens 8. The R light beam reflected by the joint surface 7 e is applied to the reflective LCD panel 13 via the condenser lens 10.
[0028]
Projection lights that form optical images of R, G, and B colors generated by the reflective LCD panels 11, 12, and 13 are incident on the color separation / combination prism 7 through condenser lenses 8, 9, and 10, respectively. The projection light of B is reflected by the surface 7f and the joint surface 7d, and the incident angle with respect to the surface 7f is approximately 0 ° and is transmitted through the surface 7f. The projected light G passes through the surface 7f as it is. The R projection light is reflected by the joint surface 7e and then passes through the surface 7f. As a result, the projection lights of the three colors are combined and emitted from the color separation / combination prism 7. The synthesized projection light is imaged on a screen (not shown) by the projection optical system 14.
[0029]
As described above, in the present embodiment, the half-wave plate is provided on the incident surface of the lens cell 6a corresponding to the P-polarized light of the second lens array, and only the S-polarized light beam is used as the illumination light. A half-wave plate may be provided on the incident surface of the lens cell 6a corresponding to S-polarized light, and only the P-polarized light beam may be used as illumination light.
[0030]
In order to uniformly illuminate the reflective LCD panels 11, 12, and 13, the light source image of the first lens array 4 formed in the second lens array 6 and the diaphragm 15 of the projection optical system 14 are conjugate. However, since the second lens array 6 is almost above the diaphragm 15 in the above configuration, the relationship is maintained.
[0031]
In this way, in order to position the second lens array 6 substantially above the stop 15, the exit pupil distance of the projection optical system 14 and the focal distances of the condenser lenses 8, 9, and 10 may be made substantially equal. On the other hand, in order to position the condenser lens 8, 9, 10 far away from the stop 15, the focal length of the condenser lenses 8, 9, 10 is increased and the distance between the reflective LCD panels 11, 12, 13 and the second lens array 6 is increased. The distance can be increased. Further, the second lens array 6 may be directly arranged at a position conjugate with the stop 15 of the projection optical system 14, but the optical system is arranged so as to form an image conjugate with the second lens array 6 here. It may be.
[0032]
As described above, in the present embodiment, a color separation / combination prism having two dichroic coat surfaces 7d and 7e is used as the color separation / combination means. In general, the wavelength range of the dichroic coated surface that is selectively transmitted varies depending on the incident angle. The degree of the change is such that the greater the design incident angle, the greater the rate of change in the characteristic wavelength range due to the angle. Therefore, in the non-telecentric optical system having a large on-axis and off-axis chief ray angle as in this embodiment, the angle of the chief ray on the axis incident on the dichroic coat surface is 35 ° or less (conditional expression 1). ).
[0033]
In addition, since the present embodiment is a non-telecentric optical system, even if the incident angle to the dichroic coated surfaces 7d and 7e is 35 ° or less, there is a slight difference in characteristics between on-axis light and off-axis light. As a method for solving this problem, there is known an inclined coating in which the characteristics of the dichroic coated surface change little by little, for example, between the upper side and the lower side of the dichroic coated surface 7e in FIG. When using the gradient coating, the dichroic coating surface on which the gradient coating is performed should be close to the reflective LCD panel. In the dichroic coating surface 7e closer to the reflective LCD panel, the place where the on-axis light and the off-axis light pass differs on the surface 7e. Inclined coating that cancels the difference. Usually, since it is the light of R and G that easily perceives color unevenness due to the difference in characteristics, it is preferable to separate the light of R and G on the surface 7e.
[0034]
When the angle of the principal ray on the axis incident on the dichroic coat surface exceeds 35 °, the incident angle increases and the color unevenness on the display surface increases. Further, when the angle is 31 ° or less (conditional expression 1 ′), a display with less color unevenness can be obtained.
[0035]
As described above, in the present embodiment, as the reflection angle conversion optical system, the decentered condenser lenses 8, 9, and 10 are disposed immediately before the respective reflective LCD panels 8, 9, and 10. If the condenser lenses 8, 9, 10 are far away from the reflective LCD panels 8, 9, 10, a long lens back is required and it is difficult to maintain the performance of the projection optical system 14, which is not preferable.
[0036]
When the image height (the length of the side of the reflective LCD panel) of the condenser lenses 8, 9, and 10 of the reflective LCD panels 11, 12, and 13 is H, the condenser lenses 8, 9, and 10 are condenser lenses. Assume that the lens optical axes α of 8, 9, and 10 are decentered parallel to the lens optical axis β of the projection optical system 14 by 0.3H to 2.0H (conditional expression 2).
[0037]
The decentering amounts of the condenser lenses 8 and 10 are the same as described above by using the optical paths β ′ and β ″ of the projection light before synthesis using the lens optical axis β of the projection optical system after synthesis as the optical path instead of β. With respect to the G projection light, the optical path of the projection light before synthesis with the lens optical axis β as the optical path is on the lens optical axis β. Β, β ′, β ″ are shown in FIG.
[0038]
If the amount of decentering is 0.3H or less, the amount of decentering is small, so that it is necessary to increase the power of the condenser lens in order to separate the illumination light and the projection light, which degrades the performance of the projection optical system. If it is 2.0H or more, since the amount of eccentricity is large, the diameter of the condenser lens is increased and the cost is increased. Furthermore, the amount of eccentricity is preferably 0.4H to 1.0H (conditional expression 2 ').
[0039]
FIG. 3 shows an optical path image diagram of the condenser lenses 8, 9 and 10 and the reflective LCD panels 11 and 1213. The lens optical axes of the condenser lenses 8, 9, and 10 are indicated by a one-dot chain line α. In FIG. 3, the illumination light from the upper right is transmitted through the decentered condenser lenses 8, 9, and 10 and is incident on the central portion P, the left portion P ′, and the right portion P ″ of the reflective LCD panels 11, 12, and 13. Then, it is reflected and again passes through the condenser lenses 8, 9, and 10 again, and goes upward in the figure.
[0040]
The incident angle of the illumination light and the reflection angle of the projection light in each region of the reflective LCD panels 11, 12, and 13 are the illumination light immediately before entering the condenser lenses 8, 9, and 10 and are emitted from the condenser lenses 8, 9, and 10. Think with the projection light immediately after. As shown in the figure, at the central portion P of the reflective LCD panels 11, 12, and 13, the incident angle is 21.9 ° and the reflection angle is −5.0 ° with respect to the surface. Illuminating light p₁, Projection light p₂Go in and out.
[0041]
In the left part P ′ of the reflective LCD panels 11, 12, and 13 shown in the same figure, the incident light is incident on the condenser lenses 8, 9, 10 at an incident angle of 25.2 ° and a reflection angle of 1.7 ° with respect to the surface.₁', Projection light p₂'Goes in and out. As described above, the condenser lenses 8, 9, and 10 correspond to the incident angle of illumination light with respect to the reflective LCD panels 11, 12, and 13 and the reflection angle of projection light with respect to the reflective LCD panels 11, 12, and 13. It is made different depending on the areas of the reflective display panels 11, 12, and 13.
[0042]
Accordingly, it is possible to make the projection optical system 14 a non-telecentric optical system while the angles of light rays incident and reflected on the elements of the reflective LCD panels 11, 12, and 13 are substantially constant. The lens diameter can be reduced and the number of lenses can be reduced to reduce costs and size. In addition, each LCD element can optimize the incident and reflection characteristics for a certain angle. This embodiment is preferable because the incident and reflection angles with respect to the LCD element can be made substantially equal in the entire area of the reflective LCD panels 11, 12 and 13 as described above.
[0043]
As described above, in the present embodiment, the projection optical system 14 can be a non-telecentric optical system. However, if the exit pupil distance of the projection optical system is too small, it is difficult to secure a lens back for inserting the color separation / combination prism 7. Accordingly, the following condition for appropriately maintaining the exit pupil distance of the projection optical system 14 is satisfied.
[0044]
  The focal length is f, the image height of the outermost axial ray on the reflective display panels 11, 12, 13 is y (the value is half the diagonal of the reflective display panel), and the maximum of the projection light incident on the projection optical system. When the angle between the principal ray of the outer axis ray and the axial principal ray is θ,(y / tan θ)/ F is 2 to 10 (conditional expression 3).(y / tan θ)If / f exceeds the lower limit, it is difficult to ensure a sufficient lens back, and if it exceeds the upper limit, the number of lenses in the projection optical system increases, resulting in an increase in cost.
[0045]
The reflective LCD panels 11, 12, and 13 correct the inclination of the image plane caused by the decentered condenser lenses 8, 9, and 10 with respect to the lens optical axis β or the optical paths β ′ and β ″ of the projection optical system. If the tilt is too small, the tilt cannot be corrected, and if it is too large, a large distortion occurs, so 2 ° <| tilt angle | <8 ° (conditional expression 4) is desirable.
[0046]
The construction data in this embodiment is shown below. The corresponding surfaces in the data are illustrated in FIG. The surface marked with * in the data is an aspheric surface, and the formulas representing the aspheric coefficient and the aspheric surface are also shown below. In addition, the amount and position of the eccentric lens are also shown separately. As shown in FIG. 1, the positional relationship of the components of the optical system is indicated by an X axis parallel to the paper surface and in the direction of the optical axis β of the projection optical system 14, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the paper surface. Represented by three-dimensional coordinates.
[0047]
This is a condenser lens 9 in which the lens having the thirteenth surface (r13) and the fourteenth surface (r14) is decentered. Although not shown in FIG. 1, the condenser lenses 8 and 10 have a thirteenth surface and a fourteenth surface similarly to the condenser lens 9.
[0048]
FIG. 4 shows aberration diagrams of the projection optical system 14. In the spherical aberration diagram of the figure, the solid line (d) represents the spherical aberration at the d line, and the broken line (SC) represents the sine condition. In the astigmatism diagram, the solid line (DS) and the broken line (DM) represent the astigmatism of the sagittal beam and the meridional beam, respectively. Here, for the sake of simplicity, the aberration in the axially symmetric state is shown by eliminating the decentering of the condenser lens.
[0049]

[0050]
[Aspherical coefficient of the 4th surface (* r4)]
ε = 0.0140437
A = 0.926527 × 10^-Five
B = −0.143572 × 10^-7
C = 0.531059 × 10^-Ten
D = −0.7159979 × 10^-13
[0051]

In this formula:
r = (y²+ Z²)^1/2
ε: quadric surface parameter
c: curvature (reciprocal of radius of curvature cr)
[0052]
[Size of reflective LCD panel]
Long side: 35.84mm
Short side (value of H): 21.5mm
[0053]
  [Focal distance of projection optical system (f)]
      28.6mm
          {(y / tan θ)Since /f=3.53, Conditional Expression 3 is satisfied}
[0054]
[Parallel eccentricity of the 13th surface (r13)]
13.907900mm (in the y-axis direction)
(13.907900 = 0.647H, so conditional expression 2 ′ is satisfied)
[0055]
[Eccentric eccentricity of image plane (r15)]
5.341089 °
(Condition condition 4 is satisfied)
[0056]
[Angle formed with the axial principal ray of the dichroic coating surface]
7d surface: 27.9 ° (conditional expression 1 ′ is satisfied)
7e surface: 32.1 ° (satisfies conditional expression 1)
[0057]
In the above-described embodiment, the color separation / combination prism 7 shown in FIG. 2 is used as the color separation / combination means. Hereinafter, other examples of the color separation / synthesis unit will be described as the second to fourth embodiments.
[0058]
<Second Embodiment>
FIG. 5 is a diagram corresponding to FIG. 2 including the color separation / combination means of the present embodiment and the condenser lenses 8, 9, 10 and the reflective LCD panels 11, 12, 13 arranged in correspondence therewith. As the color separation / combination means, a color separation / combination prism 72 composed of three prisms 72a, 72b, 72c of two hexahedral prisms 72a, 72c and one pentahedron prism 72b is used. The two prisms 72b and 72c are joined so that a joining surface 72e is formed by the prism 72b and the prism 72c. The prisms 72a and 72b are arranged with a slight air layer. Of the separated prism surfaces, the prism 72a side is the surface 72d and the prism 72b side is the surface 72g.
[0059]
A dichroic multilayer film that reflects only the B light beam and transmits the light beams of other colors is deposited on the surface 72d, and a dichroic multilayer film that reflects only the R light beam and transmits the light beams of other colors is deposited on the bonding surface 72e. A film is deposited. The angles formed by the axial principal rays of the surface 72d and the joint surface 72e are 27.9 ° and 12.4 °, respectively, and the conditional expression 1 ′ is satisfied.
[0060]
Of the illumination light incident from the surface 72f, the B light flux is reflected by the surface 72d, totally reflected by the surface 72f, and then incident on the corresponding reflective LCD panel 11. The R light beam is reflected by the joint surface 72e, totally reflected by the surface 72g, and then incident on the corresponding reflective LCD panel 13. The G light beam passes through all surfaces of the color separation / combination prism 72 and enters the corresponding reflective LCD panel 12. The projection light can be explained by following the reverse of the illumination light, so the explanation is omitted.
[0061]
  <Third Embodiment>
  Figure6FIG. 4 is a diagram corresponding to FIG. 2 including the color separation / combination means of the present embodiment, condenser lenses 8, 9, and 10 and reflection type LCD panels 11, 12, and 13 arranged corresponding thereto. As the color separation / combination means, a color separation / combination prism 73 comprising four prisms 73a, 73b, 73c, 73d of two hexahedral prisms 73a, 73d and two pentahedron prisms 73b, 73c is used. The four prisms 73a, 73b, 73c, and 73d are joined such that a joint surface 73e is formed by the prism 73a and the prism 73b, and a joint surface 73f is formed by the prism 73c and the prism 73d. The prism 73b and the prism 73c are arranged with a slight air layer. Of the separated prism surfaces, the surface on the prism 73c side is defined as a surface 73g.
[0062]
A dichroic multilayer film that reflects only the B light beam and transmits the other color light beams is deposited on the bonding surface 73e, and the dichroic that reflects only the R light beam and transmits the other color light beams is deposited on the bonding surface 73f. A multilayer film is deposited. The angles formed by the axial principal rays of the joint surface 73e and the joint surface 73f are 27.9 ° and 27.9 °, respectively, and the conditional expression 1 ′ is satisfied.
[0063]
Of the illumination light incident from the surface 73h, the B light flux is reflected by the joint surface 73e, totally reflected by the surface 73h, and then incident on the corresponding reflective LCD panel 11. The R light beam is reflected by the joint surface 73f, totally reflected by the surface 73g, and then incident on the corresponding reflective LCD panel 13. The G light flux passes through all surfaces of the color separation / combination prism 73 and enters the corresponding reflective LCD panel 12. The projection light can be explained by following the reverse of the illumination light, so the explanation is omitted.
[0064]
  <Fourth Embodiment>
  Figure7FIG. 4 is a diagram corresponding to FIG. 2 including the color separation / combination means of the present embodiment, condenser lenses 8, 9, and 10 and reflection type LCD panels 11, 12, and 13 arranged corresponding thereto. The color separation / combination means is a color separation / combination mirror 74 including two dichroic mirrors 74a and 74b. A dichroic multilayer film is deposited on the surfaces of the two dichroic mirrors 74a and 74b on which the illumination light is incident.
[0065]
The dichroic mirror 74a is deposited with a dichroic multilayer film that reflects only the B light beam and transmits the other color light beams, and the dichroic mirror 74b reflects only the R light beam and transmits the other color light beams. A multilayer film is deposited. The angles formed by the axial principal rays of the dichroic mirrors 74a and 74b are 30 ° and 30 °, respectively, and the conditional expression 1 ′ is satisfied.
[0066]
Of the illumination light, the B light flux is reflected by the dichroic mirror 74 a and enters the corresponding reflective LCD panel 11. The R light beam is reflected by the dichroic mirror 74 b and enters the corresponding reflective LCD panel 13. The G light flux passes through the two dichroic mirrors 74a and 74b and enters the corresponding reflective LCD panel 12. The projection light can be explained by following the reverse of the illumination light, so the explanation is omitted.
[0067]
【The invention's effect】
According to the color image projection apparatus of the present invention, since the illumination light and the projection light are incident and reflected at different angles, there is no need for a polarization separation prism or the like for separating the illumination light and the projection light, and the projection optical system is also non-existent. Since it is a telecentric optical system, it can be realized with a small number of lenses. Therefore, the size of the entire apparatus can be reduced, and the number of optical components and components for holding them can be greatly reduced, so that an inexpensive configuration can be achieved.
[0068]
In the present invention, since the incident angle of the illumination light to the dichroic coat surface is 35 ° or less, it is possible to display an image with high quality without color unevenness.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view of a color image projector according to a first embodiment of the present invention.
FIG. 2 is a horizontal sectional view of the color image projection apparatus according to the first embodiment of the present invention.
FIG. 3 is an optical path image diagram of a condenser lens and a reflective LCD panel.
FIG. 4 is an aberration diagram of the projection optical system in the first embodiment.
FIG. 5 is a horizontal sectional view illustrating a configuration of a color separation / combination prism according to a second embodiment.
FIG. 6 is a horizontal sectional view showing a configuration of a color separation / combination prism according to a third embodiment.
FIG. 7 is a horizontal sectional view showing a configuration of a color separation / synthesis mirror according to a fourth embodiment.
FIG. 8 is a horizontal sectional view of a conventional color image projector.
[Explanation of symbols]
1 Light source
2 reflector
4 First lens array
5 Polarization separation prism
6 Second lens array
7, 72, 73 Color separation / combination prism
8, 9, 10 condenser lens
11, 12, 13 Reflective LCD panel
14 Projection optical system
74 Color separation / synthesis mirror

Claims (6)

A plurality of display means having the same configuration having a reflective liquid crystal display panel divided into a plurality of pixels, an illumination optical system for forming illumination light to be given to the display means, and illumination light from the illumination optical system in a plurality of colors And the color separation / combination means for synthesizing the projection light of the plurality of colors formed by the plurality of display means and the color separation / combination means. A color image projection apparatus having a projection optical system that projects the projected light and forms an image on a projection surface,
The illumination light and the projection light are separated from each other by emitting the illumination light obliquely with respect to the reflective liquid crystal display panel from the color separation / synthesis unit.
A reflection angle conversion optical system between the color separation / synthesis unit and the reflective liquid crystal display panel ;
The reflection angle conversion optical system includes an angle formed by illumination light incident on the reflection angle conversion optical system with respect to a normal line of the reflective liquid crystal display panel, and projection light emitted from the reflection angle conversion optical system reflects the reflection light. The angle formed with respect to the normal line of the liquid crystal display panel differs depending on the area of the corresponding reflective liquid crystal display panel,
Projection light emitted from the reflection angle conversion optical system at an angle formed with respect to the normal line of the reflection type liquid crystal display panel by illumination light incident on the reflection angle conversion optical system at the center of the reflection type liquid crystal display panel Is larger than an angle formed with respect to the normal line of the reflective liquid crystal display panel.
The color separation / synthesis unit includes a plurality of dichroic coating surfaces that reflect only light of a specific color and transmit light of the remaining colors, and an angle formed between a normal line of the dichroic coating surface and the optical axis of the projection optical system Is 35 ° or less,
The focal length of the projection optical system is f, the image height of the most off-axis ray on the reflective display panel is y, the principal ray of the most off-axis ray of the projection light incident on the projection optical system and the principal ray on the axis. If the angle formed by is θ,
2 < (y / tan θ) / f <10 is satisfied,
A color image projection apparatus, wherein a plane including optical axes of the illumination optical system and the projection optical system is orthogonal to a plane including axial principal rays of projection light of each color . 2. The reflective liquid crystal display panel is rectangular, and a short side of the reflective liquid crystal display panel is parallel to a plane including an optical axis of the illumination optical system and the projection optical system. The color image projection device described. The color separation / combination means is a first to third prism that separates the illumination light into light in the first to third wavelength ranges and combines projection light composed of light in the first to third wavelength ranges. Formed color separation and synthesis prism,
The color separation / combination prism transmits the light in the first wavelength range, the second wavelength range, and the third wavelength range formed in the first prism in the vicinity of normal incidence, and the first wavelength above a predetermined angle. An illumination light incident surface that reflects light in the wavelength range of the first prism, a first dichroic coat surface that reflects light in the first wavelength range formed on the joint surface of the first prism and the second prism, A second dichroic coat surface that reflects light in the second wavelength band formed on the joint surface of the second prism and the third prism, and first to third prisms formed on the first to third prisms. An exit surface for guiding illumination light to the first to third reflective liquid crystal display panels corresponding to the wavelength region,
Of the illumination light, light in the first wavelength range is incident on and transmitted through the illumination light incident surface in the vicinity of normal incidence, reflected by the first dichroic coat surface, and incident on the illumination light incident surface at a predetermined angle or more. And reflected through the exit surface of the first prism and led to the first reflective liquid crystal display panel,
Of the illumination light, light in the second wavelength band is transmitted through all surfaces of the first prism, reflected by the second dichroic coat surface, transmitted through the exit surface of the second prism, and second. Led to reflective LCD display panel,
Of the illumination light, the light in the third wavelength band passes through all the surfaces of the first prism and the second prism, and passes through the exit surface of the third prism, so as to pass through the third reflective liquid crystal display panel. The color image projection apparatus according to claim 1, wherein the color image projection apparatus is guided by the following. The reflection angle conversion optical system is composed of a condenser lens disposed in the vicinity of each of the plurality of reflective liquid crystal display panels, and the optical axis of the condenser lens is the projection light emitted from the corresponding reflective liquid crystal display panel. When the image height of the reflective liquid crystal display panel in the decentering direction is H, the condenser is decentered with respect to the optical path before the synthesis of the projection light with the optical axis of the projection optical system as the optical path after synthesis. 4. The color image projector according to claim 1, wherein the optical axis of the lens is decentered in parallel with 0.3H to 2.0H. The reflection type liquid crystal display panel corrects the tilt of the image plane by the reflection angle conversion optical system, so that the projection optical system after combining the optical axis of the projection optical system out of the projection light emitted from the corresponding reflection type liquid crystal display panel. 5. The color image projection apparatus according to claim 1, wherein the color image projection apparatus is tilted from the vertical with respect to the optical path before synthesis of the projection light as the optical path. 6. The color image projector according to claim 5, wherein an inclination angle of the reflective liquid crystal display panel satisfies a conditional expression: 2 ° <| tilt angle | <8 °.

Images