WO2005124419A1

WO2005124419A1 - Projector lens and projector employing such projector lens

Info

Publication number: WO2005124419A1
Application number: PCT/JP2005/010296
Authority: WO
Inventors: Kenzaburo Suzuki
Original assignee: Nikon Corporation
Priority date: 2004-06-17
Filing date: 2005-05-31
Publication date: 2005-12-29

Abstract

A projector lens comprising, sequentially in this order from the projection surface side, a first lens group including at least two negative meniscus lenses having positive refractive power, with the convex surfaces facing toward the projection surface side and a second lens group having positive refractive power, and an aperture stop arranged between the first lens group and the second lens group wherein the first lens group includes at least one aspherical lens and the following formula: 5.5 < BF/Y < 15.0 is satisfied, where BF is back focus in terms of air, and Y is the maximum object height.

Description

Projector lens and projector device using this projector lens

The present invention relates to a projector lens for projecting an image formed by a light modulation element or the like, and a projector device using the projector lens. Background art

In recent years, various lens types have been proposed for projector lenses as the performance of projectors has increased. The projector illuminates the light modulation device (such as a liquid crystal panel (LCD) or a digital micromirror device (DMD) that drives a minute mirror in pixel units with a video signal) by transmission or reflection, and the intensity is modulated. This is an optical device that enlarges and projects the projected image over a finite distance via a lens.

In order to project a color image, a unit generally called an optical engine divided the image into three primary colors of red (R), blue (B), and green (G), and formed an image for each color via a light modulation element. After that, the color is synthesized by a dichroic prism or the like, and a color image is projected on a screen or the like by one projector lens. A single projector lens requires a sufficient amount of peripheral light and requires uniform performance over the entire screen, making it more difficult to design than a normal photographic lens.

By the way, the brightness on the screen is determined by the F-number of the projector lens and the brightness of the screen of the light modulation element. The characteristics of a projector-lens combination of plastic and glass change due to the heat generated by the light modulation element. Therefore, it is particularly necessary to design a lens according to the temperature and humidity conditions of the lens group close to the light modulation element. An analysis optical system and a color combining optical system must be placed between such a light modulator and the projector lens.

The color combining optical system includes, for example, a dichroic prism. Therefore, the distance (back focus) between the object surface (the image display surface of the light modulation element) and the vertex of the projector lens closest to it must be about 10 mm to several 10 mm. Since the back focus is limited by the focal length of the entire projector lens, such a long back focus is secured for a wide-angle projector lens with a short focal length required for a large-screen projector. It is not easy to do.

In addition, it is necessary to ensure high image quality by suppressing aberrations while ensuring back focus. In particular, the number of pixels (800 × 600 dots or 120 × 4 × 768 dots in the super video graphics array (SVGA) standard, and 128 × 960 dots in the super extended video graphics array standard) With the increase in), the miniaturization of optical modulators (the diagonal length is 1 inch or less) is progressing, so that various aberrations must be suppressed sufficiently.

Also, in order to project a display screen of a light modulation element with an effective display area of about 1 inch on a large screen that reaches 60 inches to 80 inches and even 100 inches, especially in the case of rear projection, It is preferable to shorten the projection distance and make the depth of the projection device main body sufficiently small. However, the shorter the projection distance, the larger the diameter of the projector lens. Moreover, it is necessary to make the brightness and resolution uniform on the projection screen and to suppress distortion and color shift.

Furthermore, the rear focal plane (in this embodiment, the object plane side is the front side, and the projection plane side is the rear side It is necessary to stabilize the projection magnification, make the brightness and resolution uniform, and suppress distortion and color misregistration.

As an example of a projector lens corresponding to such requirements, a first lens group having a negative refractive power and a second lens group having a positive refractive power are provided in order from the projection screen side. An aspherical lens is placed on the screen side, the air-equivalent back focus B f, the focal length f of the entire projection lens, the air-equivalent distance D 1 2 between the first and second lens groups, and the first lens group. Where f 1 is the focal length of f 1, and the following equations B f / f> 4.0, 3.0 <<D 12 / f <5.0, 1.0 <I f 1 / f I <3.0 A configuration that satisfies the requirements is disclosed (for example, see Japanese Patent Application Laid-Open No. 2003-50969). With this configuration, with the projector lens, a focal length of about 12 mm, a back focus of about 50 mm, and an angle of view of about 80 degrees can be obtained, a short projection distance, a long back focus, and good telecentricity. In addition, since the optical path can be changed internally, there is an advantage that a rear projector with a small depth can be obtained. Disclosure of the invention

Problems to be solved by the invention ''

However, in recent years, with the further miniaturization of the size of the light modulation element and the further miniaturization of the pixel pitch, the imaging performance (especially chromatic aberration) superior with the conventional projector lens, wide angle, long back focus, and small size It is extremely difficult to satisfy the requirements. In addition, when the analysis optical system used to selectively project only the light contributing to the image out of the light from the light modulation element is constituted by a wire grid type polarizing beam splitter, a conventional prism is used. I need to secure more back focus compared to the type There was a problem.

The present invention has been made in view of such a problem, and a projector lens and a projector lens capable of coping with a wide angle of view of 80 degrees or more while securing a necessary back focus. It is intended to provide a projector device used. Means for solving the problem

In order to achieve such an object, the projector lens of the present invention has at least two negative meniscus lenses having convex surfaces directed to the projection surface side in order from the projection surface side, and has a positive refractive power. A first lens group, a second lens group having a positive refractive power, and an aperture stop arranged between the first lens group and the second lens group, wherein the first lens group includes: When at least one aspherical lens is included, BF is the air-equivalent back focus, and Y is the maximum object height, the lens satisfies the following equation: 5.5 <BF / Y <15.0. The invention's effect

As described above, according to the present invention, it is possible to realize a projector lens capable of supporting a wide angle of view of 80 degrees or more and a projector device using the projector lens while securing a necessary back focus. . Brief Description of Drawings

FIG. 1 is a lens configuration diagram of Example 1 of a projector lens according to the present invention.

FIG. 2 is a diagram illustrating various aberrations of the projector one lens according to the first embodiment. FIG. 3 is a lens data table of the projector lens according to the first embodiment. is there.

FIG. 4 is a lens configuration diagram of Embodiment 2 of the projector lens according to the present invention.

FIG. 5 is a diagram illustrating various aberrations of the projector lens according to the second embodiment. FIG. 6 is a lens data table of the projector lens according to the second embodiment.

FIG. 7 is a lens configuration diagram of Example 3 of the projector-one lens according to the present invention.

FIG. 8 is a diagram illustrating various aberrations of the projector lens according to the third embodiment. FIG. 9 is a lens data table of the projector lens according to the third embodiment.

FIG. 10 is a table showing conditions corresponding values of the projector lenses according to Examples 1 to 3 above.

FIG. 11 is a configuration diagram of a projector device according to the present invention.

FIG. 12 is another configuration diagram of the projector device according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The projector lens of the present invention includes, in order from the projection surface side, at least two negative meniscus lenses having convex surfaces facing the projection surface side, a first lens group having a positive refractive power, and a positive refractive power. A second lens group having a power, and an aperture stop disposed between the first lens group and the second lens group, the first lens group including at least one aspheric lens, and Assuming that the converted back focus is BF and the maximum object height is Y, the following formula (1) is satisfied.

5.5 <BF / Y <15.0. 0 ... (1)

Conditional expression (1) is a necessary condition for obtaining a sufficiently long back focus BF as a projector lens for electronic imaging equipment. Electronic imaging equipment In the optical system for the camera, it is necessary to secure the back focus BF, which is the distance from one lens of the projector to the object plane (the image display surface of the display device such as a liquid crystal panel) in order to arrange the color separation / color synthesis optical system. There is. In addition, if the back focus BF is made sufficiently long so that the angle dependence of the reflection and transmission characteristics of the dielectric reflection film used in the color separation / synthesis optical system can be neglected, shading (on the projection surface) The brightness distribution in the image, which usually becomes dark around the image).

However, if the upper limit of conditional expression (1) is exceeded, the back focus BF becomes too long, and the overall length of the lens system becomes longer, which in turn leads to an increase in the size of the lens system, which is inconvenient. Also, the lens diameter of the first lens group becomes excessively large, which is inconvenient. On the other hand, when the value goes below the lower limit of conditional expression (1), the back force BF becomes too short, and it is necessary to secure a space for disposing a filter or a prism in the optical path between the projector lens and the light modulation element. Becomes difficult. In addition, the position of the entrance pupil (in the present embodiment, the object surface side is the incident side and the projection surface side is the exit side) is too close to the light modulation element, so that the above-mentioned shading is likely to occur, which is inconvenient.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (1) to 8.0. The lower limit is preferably set to 6.0. In the projector lens of the invention, the first lens group has a positive power, and the second lens group has a positive power. Assuming that the first lens group has negative power and the second lens group has positive power, when projecting an image with a wide angle of view exceeding 80 °, the position of the lens moves to the minus side. Easy to grow. In addition, astigmatism also easily occurs. However, if the first lens group is configured to have a positive power and the second lens group is configured to have a positive power as in the present invention, the power arrangement becomes symmetrical with respect to the diaphragm, so that the distortion is reduced. And reduce astigmatism. It is convenient.

In relation to the conditional expression (1), it is preferable that a negative meniscus lens having a convex surface facing the projection surface side is disposed in the first lens unit. This is important for achieving high performance corresponding to a wide angle of view of 80 degrees or more. In particular, it is a necessary condition to sufficiently correct distortion and astigmatism. Further, it is preferable that the first lens group includes an aspheric lens having a convex surface facing the projection surface side. This is because it is effective not only for correcting coma astigmatism but also for reducing the number of lenses among various aberrations.

In the projector lens according to the present invention, it is preferable that the following expression (2) is satisfied, where Y is the maximum object height and dm is the largest lens surface distance in the first lens group.

8.0 <d m / Y <15 .0 ... (2)

Conditional expression (2) is a condition for realizing a projector lens with a minimum number of lenses while securing the necessary back focus.

If the upper limit of conditional expression (2) is exceeded, the overall length of the optical system becomes too long, which is disadvantageous because the lens diameter in front of the force / diaphragm becomes large. In addition, there is a disadvantage that distortion and chromatic aberration of magnification increase. On the other hand, when the value goes below the lower limit of conditional expression (2), sufficient back focus cannot be obtained, and the eccentric sensitivity of the lens component closest to the object side becomes too sensitive, which makes it difficult to manufacture. Also, the Petzval sum is biased to the negative side, and the occurrence of field curvature increases.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (2) to 12.0. The lower limit is preferably set to 9.0.

In the projector lens of the present invention, the second lens group includes at least two cemented lenses, and the focal length of the entire lens system is f, and the entire length of the lens system (on the optical axis from the front lens surface to the rear lens surface). Where TL is the distance of It is preferable to satisfy (3).

0. 0 1 5 <f / T L <0.1 ... (3)

Conditional expression (3) specifies an appropriate value of the ratio of the focal length f of the entire projector lens to the total length TL of the projector lens.

If the upper limit of conditional expression (3) is exceeded, the total length TL of the lens system becomes too small compared to the focal length f. As a result, the error in the air-equivalent distance between the first lens unit and the second lens unit becomes large. The sensitivity becomes too large, and it is difficult to assemble. In addition, coma aberration and field curvature are excessively generated, and it is difficult to correct them, so that good imaging performance cannot be obtained. On the other hand, when the value goes below the lower limit of conditional expression (3), the total length TL becomes too large compared to the focal length f. As a result, the front lens diameter increases, which is inconvenient. In addition, chromatic aberration of magnification tends to increase, which is inconvenient.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (3) to 0.06. The lower limit is preferably set to 0.02. In order to more sufficiently correct chromatic aberration, it is preferable that a cemented convex lens composed of a concave lens and a convex lens is provided on the most open aperture side in the first lens group in order from the projection surface side.

In the projector lens of the present invention, the first lens group includes at least one concave meniscus lens made of glass having an Abbe number of 57 or more, and the second lens group includes a glass made meniscus having an Abbe number of 70 or more. When one or more lenses are included and the distance on the optical axis from the lens surface closest to the projection surface to the aperture stop is A, and the distance on the optical axis from the lens surface closest to the object surface to the aperture stop is B, It is preferable to satisfy the following expression (4).

1.0 <A / B <4.0 ... (4)

Conditional expression (4) defines an appropriate position of the aperture stop in the optical system. Conditional expression

As a prerequisite for satisfying (4), the first lens group is used to correct various aberrations. It is preferable to have at least one concave meniscus lens on the side closest to the projection surface. Further, these lenses are preferably constituted by lenses having an Abbe number of 57 or more. As a result, chromatic aberration of magnification can be particularly well corrected.

If the upper limit of conditional expression (4) is exceeded, the position of the aperture stop is too close to the object plane (image display element) side, which is disadvantageous because it tends to deviate from telecentric imaging. In addition, distortion tends to occur on the negative side, resulting in barrel distortion, which makes correction difficult and inconvenient. On the other hand, if the lower limit of conditional expression (4) is not reached, the position of the aperture stop is too close to the projection surface side, which is inconvenient because it tends to shift from telecentric imaging. In addition, distortion is likely to occur on the positive side, resulting in pincushion distortion, which makes correction difficult and inconvenient.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (4) to 3.0. Further, the lower limit is preferably set to 2.0. In order to sufficiently exhibit the effects of the present invention, it is more preferable that the first lens group includes two glass lenses having an Abbe number of 57 or more.

The projector lens of the present invention can satisfy the following expression (5), where R is the radius of curvature of the object-side surface of the negative meniscus lens closest to the projection surface, and f is the focal length of the entire lens system. preferable.

R / f ku 8.0... (5)

Conditional expression (5) specifies an appropriate ratio of the radius of curvature of the surface of the negative meniscus lens closest to the projection surface to the object surface and the focal length f of the entire lens system to R. By satisfying conditional expression (5), distortion and astigmatism can be sufficiently corrected.

In the projector lens of the present invention, the first lens group includes two or more concave meniscus lenses made of glass having an Abbe number of 65 or more, and the second lens group has a low dispersion having an Abbe number of 70 or more. Glass and high refractive index glass with a refractive index of 1.7 or more When the focal length of the concave lens at the center of the three-piece laminated lens is f L and the combined thickness of the three-piece laminated lens is d, the following equation (6) Is preferably satisfied.

0. 2 <I ί h \ / d 7. 0 ... (6)

Conditional expression (6) defines the power of the concave lens in the three cemented lenses.

If the upper limit of conditional expression (6) is exceeded, the focal length of the concave lens in the three-element cemented lens will be too large, and the achromaticity will be insufficient, resulting in a disadvantage that good imaging performance cannot be obtained. Occurs. On the other hand, when the value goes below the lower limit value of conditional expression (6), the focal length of the concave lens in the three-piece cemented lens becomes too small, and the Petzval sum of the entire lens easily transitions to the negative side. There is a disadvantage that the music becomes large and good imaging performance cannot be obtained.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (6) to 0.35. The lower limit is preferably set to 5.0. In the second lens group, it is desirable that a low dispersion glass having an Abbe number of 70 or more is disposed closest to the object plane, which is effective for correcting lateral chromatic aberration. Further, the shape is more preferably a biconcave lens having a surface with a strong curvature on the object surface side.

Further, it is preferable that at least one glass lens having an Abbe number of 80 or more is included in the three cemented lenses in the second lens group. In order to exhibit more effects, it is more preferable to have two glass lenses having an Abbe number of 80 or more.

In the projector lens according to the aspect of the invention, the three cemented lenses may include, in order from the projection surface, a convex lens, a concave lens, and a convex lens. And the wavelength is 5466.07 nm, which is green), where Δ 1 and Δ 2 are in order from the projection surface side, It is preferable that the following expression (7) is satisfied.

0.2 <(| Δ 1 | + | Δ 2 |) 2 ... (7)

Conditional expression (7) defines the refractive index difference at the interface in the three-piece bonded lens.

It is desirable that the refractive index differences Δ 1, Δ 2 in the three-piece bonded lens have a predetermined difference in correcting aberration. When the value goes below the lower limit of conditional expression (7), it becomes difficult to correct spherical aberration among various aberrations, and good imaging performance cannot be obtained, which is inconvenient.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the lower limit of conditional expression (7) to 0.25.

In the projector lens of the present invention, it is preferable that when the focal length of the first lens group is f1 and the focal length of the second lens group is f2, the following expression (8) is satisfied.

0.5 k f 1 / f 2 <3.0 ... (8)

Conditional expression (8) defines an appropriate range for the ratio of the focal length f 1 of the first lens group G 1 to the focal length f 2 of the second lens group.

When the value exceeds the upper limit of conditional expression (8), the focal length f1 of the first lens group becomes relatively too large, and spherical aberration becomes large, which is inconvenient. In addition, the Petzval sum of the entire lens becomes too large on the positive side, so that good imaging performance cannot be obtained. On the other hand, when the value goes below the lower limit of conditional expression (8), the focal length f 2 of the second lens group becomes relatively too small, and the Petzval sum of the entire lens becomes too large on the positive side, resulting in good imaging. Performance will not be obtained.

In order to sufficiently exhibit the effects of the present invention, it is preferable to set the upper limit of conditional expression (8) to 1.5. Further, the lower limit is preferably set to 0.7. Further, in the present invention, the following conditional expressions (9) and (10) are satisfied. It is preferable to satisfy.

In the projector lens of the present invention, the difference between the Abbe number of the convex lens on the projection surface side and the Abbe number of the concave lens bonded thereto is defined as ΔV 1, and the concave lens and the object surface side bonded thereto are defined as ΔV 1. When the difference from the Abbe number of the convex lens is ΔV 2, it is preferable to satisfy the following expression (9). In this embodiment, the Abbe numbers are F line (wavelength 486.13 nm, blue), C line (wavelength 656.27 nm, red), d line (wavelength 5 8 7. 56 nm, yellow) is derived using the refractive indices n F, n C, and nd.

15.0 <(| Δ ν ΐ | / | Δ ν 2 I) / 2 <45.0 ... (9) Conditional expression (9) satisfies the Abbe number of the interface of the three laminated lenses. Define an appropriate range for the difference V 1, ΔV 2.

If the value exceeds the upper limit of conditional expression (9), the achromaticity tends to be excessive (that is, the chromatic aberration (longitudinal chromatic aberration) on the short wavelength axis is excessive), and a disadvantage that good imaging performance cannot be obtained. Occurs. On the other hand, when the value goes below the lower limit of conditional expression (9), the achromaticity tends to be insufficient (that is, the chromatic aberration on the short wavelength axis is under), and a disadvantage that good imaging performance cannot be obtained occurs.

In order to sufficiently exert the effects of the present invention, it is preferable to set the upper limit of conditional expression (9) to 35 °. The lower limit is preferably set to 18.0.

The projector lens of the present invention preferably satisfies the following expression (10) when the focal length of the entire lens system is ί and the back focus with respect to the focal length f of the entire lens system is BF.

4.5 <BF / f <15.0 ... (1 0)

Conditional expression (10) is to incorporate a glass member of sufficient thickness into the space secured by the back focus (in other words, a three-color combining prism (color combining optical system) or a polarizing beam splitter (color separation optical system). System)) Stipulate important conditions for

If the upper limit of conditional expression (10) is exceeded, the back focus becomes too long, and the overall length of the projector lens becomes longer, which in turn leads to a larger projector lens. On the other hand, when the value goes below the lower limit of conditional expression (10), the back focus becomes too short, and the color separation / synthesis optical system is arranged in the optical path between the projector lens and a light modulation element such as a liquid crystal display element. It will be difficult to secure space for this.

In order to achieve the effect of the present invention more sufficiently, it is preferable to set the upper limit of conditional expression (10) to 8.0. Further, the lower limit is preferably set to 5.0.

The main design conditions (1) to (10) for the projector lens of the present invention have been described above. However, there are some other points to keep in mind in designing.

First, in the projector lens of the present invention, it is preferable that the object plane be telecentrically imaged on the projection plane in order to prevent color shading. For this reason, it is preferable that the chief ray angle be within ± 2 degrees with respect to the optical axis. That is, it is important to appropriately set the arrangement of the lenses and the aperture stop in the second lens group.

Further, in actually configuring the projector lens of the present invention, it is preferable that the aspheric lens arranged in the first lens group is made of PMMA (methyl methacrylate). If the aspheric surface is formed as a convex surface on the side of the projection surface in the first lens group, it is possible to achieve both correction of off-axis aberrations such as curvature of field and ease of manufacture, and a more preferable shape. Become.

In the projector lens of the present invention, it is preferable that any one of the lens surfaces in the second lens group is an aspheric surface in order to achieve better imaging performance. In addition, it is preferable that the aspherical surface is a composite aspherical surface in terms of manufacturing. preferable. Note that a composite aspherical surface is one in which an aspherical surface is formed with a thin resin layer on the surface of a glass lens. In the present invention, forming an aspherical surface with a resin on the surface of a general spherical lens is cost-effective. This is preferable because it does not cause an increase in Further, the projector lens of the present invention is preferably used at an angle of view of 80 degrees or more and a projection magnification (ratio of object height to projection height) in a range of -0.006 to -0.01. In this range, very good imaging performance can be obtained. At this time, it is preferable to arrange a concave meniscus lens with the convex surface facing the projection surface on the most object side.

Further, the focusing to a magnification other than the reference magnification may be performed by moving any lens in the optical system, but is preferably performed by a so-called front focus method in which only the first lens group is extended. This is because there is little variation in aberrations such as spherical aberration and curvature of field, and focusing can be performed while maintaining good imaging performance.

In order to sufficiently correct longitudinal chromatic aberration, it is preferable to arrange a cemented convex lens closer to the object surface of the first lens group (that is, immediately before the aperture stop). More preferably, the cemented convex lens is a cemented lens composed of a concave lens and a convex lens in order from the projection surface side. Further, it is preferable that the difference in the refractive index at e-line is within 0.2.

In addition, it is preferable that both surfaces sandwiching the stop are surfaces having a large radius of curvature in order to correct spherical aberration among various aberrations. More specifically, the absolute value of the radius of curvature is more preferably 50 mm or more.

Needless to say, if a gradient index lens, a diffractive optical element, etc. are added to the present optical system, the design becomes easy and good performance can be obtained.

With the above configuration, the length of the back focus of the projector lens of the present invention is optimized with respect to the maximum height of the object plane (light modulation element), so that the projector lens can be prevented from increasing in size. Also, telecentric on the object side Since it is an optical system, color shading can be suppressed. In addition, since the focal length is optimized with respect to the total length of one lens of the projector, aberrations such as coma, curvature of field, and chromatic aberration of magnification can be suppressed, and an increase in the front lens diameter can be suppressed. Since the radius of curvature of the concave meniscus lens closest to the projection surface on the object surface side is optimized with respect to the focal length of the projector lens, distortion and astigmatism can be sufficiently corrected. Furthermore, since the focal length of the first lens group is optimized with respect to the focal length of the second lens group, spherical aberration can be sufficiently corrected.

As a result, according to the present invention, a high-definition projector can be provided, which has a field of view of 80 degrees or more, and ensures a sufficient length of back focus, thereby suppressing color shading and various aberrations. You can get a lens. Note that the projector lens of the present invention is particularly suitable for a rear-projection television because of its wide angle and long back focus.

Hereinafter, Examples 1 to 3 of the present invention will be described with reference to the accompanying drawings. In each of Examples 1 to 3, the aspheric surface has a height in the direction perpendicular to the optical axis as y, and a distance along the optical axis from a tangent plane at the vertex of the aspheric surface to a position on the aspheric surface at height y. (Sag amount) to Z, vertex radius of curvature! "When a conical coefficient / c, the n-th order aspherical coefficient was C _n, is expressed by the following conditional expressions (1 1).

S (y) = (y ² / r) / {1 + (1 κ · y ² Z r ² ) ^1/2 }

+ C ₄ y ⁴ + C ₆ y ⁶ -t C ₈ y ⁸ + C ₁₀ y ¹⁰ ... The values (condition-corresponding values) are summarized in Fig. 1 ◦ below.

(Example 1)

Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS.

FIG. 1 is a lens configuration diagram of a projector lens according to a first embodiment. As shown in FIG. 1, the projector lens according to the present embodiment includes an L 1 having three concave meniscus lenses having a convex surface directed from the projection surface side to the projection surface side, a mirror L 2, and a projection surface side. A first lens group G 1 having L 3, comprising a cemented lens (doublet) of a concave meniscus lens having a convex surface facing the convex surface and a convex meniscus lens having a convex surface facing the projection surface, and a convex surface facing the object surface. L4 composed of a laminated lens (triplet) of a convex meniscus lens, a biconcave lens and a biconvex lens aimed at, and L composed of a laminated lens of a biconvex lens, a concave meniscus lens and a concave meniscus lens 5, a second lens group G2 having a biconvex lens L6, an aperture stop S disposed between the first lens group G1 and the second lens group G2, System '' Color composite light It is configured to include Science C.

The analysis and color synthesis optical system c is composed of a color synthesis optical system, an analysis optical system, and a parallel plate glass in order from the projection surface side, and the parallel plate glass is an image of a light modulation element such as a liquid crystal display element. It is arranged to face the display surface D.

Further, in L1 including the three concave meniscus lenses of the first lens group G1, the object-side surface of the lens closest to the object surface is aspheric.

In the triplet L5 of the second lens group G2, the surface closest to the object plane is an aspheric surface. More specifically, the triplet L5 forms a concave meniscus lens with resin on the other lens surface of the concave meniscus lens joined to the biconvex lens, and the object-side surface of the concave meniscus lens made of resin is It is a compound aspherical lens having an aspherical shape.

FIG. 2 is a diagram showing various aberrations in the first embodiment. Each aberration diagram shows the results for the d-line (587.56 nm, yellow) and g-line (435.884 nm, blue). In each aberration diagram (excluding distortion diagrams), d-line and C-line are shown as G and D, respectively. Also, each aberration diagram shows the light from the projection surface to the object surface. The line is traced back to show its imaging characteristics (aberration). The description of the aberration diagrams is the same in the other embodiments.

Figure 2 (a) shows longitudinal spherical aberration (axial spherical aberration). The vertical axis is NA (maximum 0.17), and the horizontal axis is Funoreschenore 0.2 O Omm. The point at which the paraxial ray of the d line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from Fig. 2 (a), the maximum value of longitudinal spherical aberration is about 0.03 mm with respect to the d-line when NA is 0.17, and is sufficiently small.

FIG. 2 (b) shows astigmatism. The vertical axis is the height Y on the object plane (maximum 6.61 mm), and the horizontal axis is the Funore scale 0.20 mm. The point at which the paraxial ray of the d-line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from Fig. 2 (b), the maximum value of astigmatism is for the sagittal surface when the height Y on the object plane is 6.6 lmm, and is 0.0 for the d-line. It is about 4 mm, which is sufficiently small.

FIG. 2 (c) shows distortion. The vertical axis is the height Y on the object plane (maximum 6.61 mm), and the horizontal axis is the hunore sky knore 5.0000%. As can be seen from Fig. 2 (c), the maximum value of the distortion is a value when the height Y on the object plane is 6.61 mm and is about -0.8%, which is sufficiently small. Have been.

Figure 2 (d 1), (d 2), and (d 3) show the lateral spherical aberration, where the height Y on the object plane is 6.61 mm, 4.63 mm, and 0.00 mm, respectively. (The corresponding heights on the projection surface are minus 81.8.90 mm, minus 61.6.11 mm, and 0.00.0 mm, respectively). The vertical axis is full scale 0.05 mm. The horizontal axis is the median plane coordinates on the exit pupil (the object side (image display surface D) side is the entrance side and the projection side is the exit side). The center of the horizontal axis (origin) is the center of the exit pupil. It is. The full scale on the horizontal axis is the maximum height at which the incident light beam passes through the exit pupil. Figure 2 From (dl), (d2), (d3) As described above, the maximum value of the lateral spherical aberration is about 0.02 mm with respect to the g-line when the height Y on the object plane is 6.6 lmm, and is sufficiently small.

Thus, in the projector lens of Example 1 shown in FIG. 2, it can be seen that various aberrations are satisfactorily corrected and good imaging performance is secured.

FIG. 3 is a lens data table according to the first embodiment. In Fig. 3, there are planes from plane 0 (projection plane) to plane 28 (object plane). The 0th surface is a projection surface, and the distance on the optical axis to the 1st surface is 880.00000 mm, but the description is omitted. In addition, the 27th (flat) to 28th planes are air layers, and the spacing between them is 1.50279 mm. However, the 28th plane does not appear directly in FIG.

The radius of curvature r is positive when the center is on the rear side (the object plane (image display plane D) side). Further, the surface distance d, for example, the surface distance described in the first surface column is the distance between the first surface and the second surface. The material materia1 is described as resin only when it is a resin. However, when the refractive index is not described, it is air, and when the refractive index is described but matteria1 is not displayed, it is glass. As the refractive index, a value nd for the d line (58.75.6 nm) and a value ng for the g line (43.58.4 nm) are described. In addition, the final number V d is F line (48.6.13 nm, blue). Using the refractive indices n F, n C, and nd for the line (65.27 nm, red) and the d line (587.56 nm, yellow), (nd_l) / (n F- n C). Hereinafter, the description of the lens data table is the same in the other embodiments.

In the projector lens according to Example 1 illustrated in FIG. 3, the first lens group G 1 includes the first to eleventh surfaces, the aperture stop S includes the first and second surfaces, and the second lens group includes the second lens group. It is composed of 13 surfaces and 2nd and 2nd surfaces. The sixth surface and the 20th surface are aspherical surfaces, and these aspherical surfaces are represented by a conical coefficient k, C 4, C 6,... The sixth surface is the object-side final surface of L1 composed of three concave meniscus lenses in the first lens group G1. The aspheric lens composed of the fifth and sixth surfaces is made of resin (PMMA) with a thickness of 2.1820.1 mm on the optical axis. The twentieth surface is the object-side final surface of the triplet L5 in the second lens group G2. The aspheric lens composed of the 19th and 20th surfaces is a resin lens with a thickness of 0.2000 mm on the optical axis, and the lens composed of the 17th to 20th surfaces is a compound lens. It is an aspheric lens. The total thickness on the optical axis from the 2nd surface to the 28th surface is 56.592279 mm, which is expressed in terms of air-equivalent back focus (see Fig. 10). 6 Omm.

The focusing on the projection surface by the projector lens according to the first embodiment is because the method of extending only the three concave meniscus lenses L1 of the first lens group G1 suppresses aberration. preferable.

Further, the projector lens according to Example 1 satisfies all of the conditional expressions (1) to (10) as shown in FIG. 10, and the value of the maximum object height Y is 6.61 mm. Although it is very small compared to conventional projectors, it can project a good image with a large angle of view of 83.4 degrees, with various aberrations suppressed. The knock focus BF can be as large as 39.76 mm. Further, the number of lenses in the first lens group is five, and the number of lenses in the second lens group is six.

(Example 2)

Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a lens configuration diagram of a projector lens according to the second embodiment. As shown in FIG. 4, the projector lens according to the present embodiment L1 consisting of three concave meniscus lenses with the convex surface facing the side, a flare stop, and a cemented lens consisting of a concave meniscus lens with the convex surface facing the projection surface and a convex meniscus lens with the convex surface facing the projection surface (Doublet), a first lens group G1 having L2, a convex meniscus lens having a convex surface facing the object surface side, a cemented lens of a biconcave lens, and a biconvex lens (triplet). 3, a second lens group G2 having a bi-convex lens, a concave meniscus lens, a laminated lens (triple) of a concave meniscus lens, a second lens group G2 having a bi-convex lens L5, and a first lens It comprises an aperture stop S disposed between the group G 1 and the second lens group G 2, and an analysis optical system / color combining optical system C.

In the lens configuration of the first lens group G1, in Example 1, the distance between L1 composed of three concave meniscus lenses and the doublet L3 (the sixth surface and the second lens in the lens data table shown in FIG. 3) was set. In the second embodiment, the mirror L 2 is disposed between the L 1 (three concave meniscus lenses) and the doublet L 2 (the lens shown in FIG. 6). The flare stop is placed between the sixth and eighth surfaces in the data table). However, also in the second embodiment, a bending mirror may be arranged, for example, between the lens L 1 and the flare stop (between the sixth and seventh surfaces in the lens data table shown in FIG. 6). Can be placed at any position.

The colorimetric optical system C consists of a color composite optical system, an analytical optical system, and a parallel plate glass in order from the projection surface side.The parallel plate glass is an image of a light modulation element such as a liquid crystal display element. It is arranged to face the display surface D.

In the triplet L4 of the second lens group G2, The surface is aspheric. More specifically, the triplet L4 forms a concave meniscus lens with resin on the other lens surface of the concave meniscus lens joined to the biconvex lens, and the object-side surface of the concave meniscus lens made of resin is It is a compound aspherical lens having an aspherical shape.

FIG. 5 is a diagram of various aberrations in the second embodiment. Figure 5 (a) shows longitudinal spherical aberration (axial spherical aberration). The vertical axis is NA (maximum 0.14) and the horizontal axis is full scale 0.20 mm. The point at which the paraxial ray of the d-line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from Fig. 2 (a), the maximum value of the longitudinal spherical aberration is about -0.04 mm for the g-line when NA is 0, and is sufficiently small.

FIG. 5 (b) shows astigmatism. The vertical axis is the height Y (maximum 8.92 mm) on the object plane, and the horizontal axis is full scale 0.20 mm. The point at which the paraxial ray of the d-line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from Fig. 5 (b), the maximum value of astigmatism is for the sagittal plane when the height Y on the object plane is 8.92 mm, and is 0.0 for the d-line. It is about 44 mm, which is sufficiently small.

FIG. 5 (c) shows distortion. The vertical axis is the height Y (maximum 8.92 mm) on the object plane, and the horizontal axis is 5.000% of full scale. As can be seen from Fig. 5 (c), the maximum value of the distortion is the value when the height Y on the object plane is 8.92 mm, and is about minus 1.0%. Have been.

Fig. 5 (d1), (d2), and (d3) show lateral spherical aberration, and the height Y on the object plane is 8.92 mm, 6.18 mm, and 0.00 mm, respectively. (The corresponding heights on the projection plane are minus 85.8.04 mm, minus 59.4.35 mm, and 0.00.0 mm, respectively). The vertical axis is full scale 0.05 mm. The horizontal axis is the exit pupil (the object plane (image display plane D) side (The entrance side and the projection surface side are defined as the exit side). The center of the horizontal axis (origin) is the center of the exit pupil. The full scale on the horizontal axis is the maximum height at which the incident light beam passes through the exit pupil. As can be seen from Fig. 5 (dl), (d2), and (d3), the maximum value of the lateral spherical aberration is the value for the g-line when the height Y on the object plane is 8.92 mm. ◦ It is about 26 mm, which is sufficiently small.

Thus, in the projector lens of Example 2 shown in FIG. 5, it can be seen that various aberrations are satisfactorily corrected, and good imaging performance is secured.

FIG. 6 is a lens data table according to the second embodiment. In Fig. 6, planes exist from the 0th plane (projection plane) to the 27th plane (object plane). The 0th plane is the projection plane, and the distance on the optical axis to the 1st plane is 79.6.40 000 mm, but the description is omitted. Also, the 26th (flat) to 27th surfaces are air layers and the spacing is 2.04056 mm, but the 27th surface does not appear directly in FIG.

In the projector lens according to Example 2 shown in FIG. 6, the first lens group G1 includes the first to tenth surfaces, the aperture stop S is the first surface, and the second lens group is the first lens group. It is composed of 1st to 2nd surfaces. The sixth surface and the nineteenth surface are aspherical surfaces, and these aspherical surfaces are represented by a conical coefficient k, C 4, C 6,... The sixth surface is the object-side final surface of L1 composed of three concave meniscus lenses in the first lens group G1. The aspheric lens composed of the fifth and sixth surfaces is made of resin (PMMA) with a thickness of 2.9700 Omm on the optical axis. The ninth surface is the object-side final surface of the triplet L4 in the second lens group G2. The aspheric lens composed of the 18th and 19th surfaces is a resin lens with a thickness of 0.27000 mm on the optical axis, and is composed of the 16th to 19th surfaces Is a compound aspherical lens. Also, the total thickness on the optical axis from the 21st surface to the 27th surface is 65.40956mm, Expressed in terms of air equivalent back focus (see Fig. 10), it is 54.447 mm.

Note that focusing on the projection surface by the projector lens according to the second embodiment is different from the method in which only the three concave meniscus lenses L1 of the first lens group G1 are extended to suppress aberration. Is preferred.

As shown in FIG. 10, the projector lens according to Example 2 satisfies all of the conditional expressions (1) to (10), and the maximum object height Y is 8.922 mm. In spite of its extremely small size compared to conventional projectors, it can project a good image with a large angle of view of 91.3 degrees while suppressing various aberrations. Also, the knock focus B F can be as large as 54.4747 mm.

As described above, in Embodiment 2, since a large back focus can be obtained, the degree of freedom in the layout design of the optical member between the light modulation element and the projector lens is increased. For example, when a wire-grid polarizing beam splitter is used instead of a prism-type polarizing beam splitter as the analyzing optical system, the optical path of the analyzing optical system filled with glass is used. Is filled with air having a refractive index of 1 or nitrogen gas, the back focus in air of the second embodiment needs to be longer than that of the first embodiment. Even when such a long air-equivalent back focus is required, the projector lens of the second embodiment can be applied.

Similarly to the first embodiment, the projector lens of the second embodiment has a small number of lenses, that is, five lenses in the first lens group and six lenses in the second lens group, that is, a total of 11 lenses. can do.

(Example 3) Hereinafter, a third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a lens configuration diagram of a projector lens according to the third embodiment. As shown in FIG. 7, the projector lens according to the third embodiment includes, from the projection surface side, L 1 composed of three concave meniscus lenses with the convex surface facing the projection surface side, and L 2 composed of a biconcave lens. A first lens group G 1 having a concave meniscus lens L 3, a concave meniscus lens and a bi-convex lens L 4, and a convex meniscus lens, a bi-concave lens and a bi-convex lens L5 consisting of a lens (triplet) bonded to a lens, L6 consisting of a lens (doublet) consisting of a concave meniscus lens and a biconvex lens, and bonding of a convex meniscus lens and a concave meniscus lens A second lens group G2 having a lens (doublet) L7 and a biconvex lens L8; and a second lens group G2 disposed between the first lens group G1 and the second lens group G2. That it configured to include an aperture stop S, and a detection optical system and color synthesis optical system C.

In the third embodiment, unlike the above-described two embodiments, a biconcave lens L2 and a concave meniscus lens 3 are arranged at a portion of the first lens group having the largest inter-lens distance. Therefore, the third embodiment does not satisfy the above conditional expression (2). In the third embodiment, a cemented lens L6 is added to the second lens group, so that a total of three cemented lenses are provided. Further, the third embodiment has a configuration in which the second lens group does not have an aspherical lens, and has only one aspherical surface arranged in the first lens group. It should be noted that a concave meniscus lens having a refractive index of 1.6 or more is adjacent to the front and rear of the aspheric lens arranged in the second lens group.

The first lens group G1 has three concave meniscus lenses L1. In this case, the surface on the object surface side of the lens disposed closest to the object surface is an aspheric surface. In the third embodiment, this is the only aspheric lens.

FIG. 8 is a diagram of various aberrations in the third embodiment. Figure 8 (a) shows longitudinal spherical aberration (axial spherical aberration). The vertical axis is NA (maximum 0.17), and the horizontal axis is full scale 0.20 mm. The point at which the paraxial ray of the d-line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from FIG. 8 (a), the maximum value of the longitudinal spherical aberration is about 0.04 mm with respect to the g-line when NA is 0.17, and is sufficiently small.

FIG. 8 (b) shows astigmatism. The vertical axis is the height Y above the object plane (up to 6.40 mm), and the horizontal axis is 0.20 mm full scale. The point at which the paraxial ray of the d-line crosses the optical axis is set as the base point of the horizontal axis. As can be seen from Fig. 8 (b), the maximum value of astigmatism is for the median surface when the height Y on the object plane is 6.4 O mm, and is 0 for the d-line. It is about 3 mm, which is sufficiently small.

FIG. 8 (c) shows distortion. The vertical axis is the height Y on the object plane (up to 6.40 mm), and the horizontal axis is 5.000% of full scale. As can be seen from Fig. 8 (c), the maximum value of the distortion is when the height Y on the object plane is 6.4 Omm, and is about -0.4%, which is sufficiently small. Have been.

Fig. 8 (d1), (d2), and (d3) show the lateral spherical aberration, where the height Y on the object plane is 6.40 mm, 4.48 mm, and 0.00 mm, respectively. (The corresponding heights on the projection surface are minus 78.3.04 mm, minus 61.3.35 mm, and 0.00.0 mm, respectively). The vertical axis is full scale 0.05 mm. The horizontal axis is the median plane coordinates on the exit pupil (the object side (image display surface D) side is the entrance side and the projection side is the exit side). The center of the horizontal axis (origin) is the center of the exit pupil. It is. Full scale on horizontal axis is incident light The maximum height at which the line passes through the exit pupil. As can be seen from Fig. 8 (d1), (d2), and (d3), the maximum value of the lateral spherical aberration is the value for the g-line when the height Y on the object plane is 6.4 Omm. It is about 0.01 mm, which is sufficiently small.

Thus, in the projector lens of Example 3 shown in FIG. 8, it can be seen that various aberrations are satisfactorily corrected and good imaging performance is secured.

FIG. 9 is a lens data table according to the third embodiment. In FIG. 9, planes exist from the 0th plane (projection plane) to the 32nd plane (object plane). The 0th plane is the projection plane, and the distance on the optical axis up to the 1st plane is 730.000 000 mm, but the description is omitted. In addition, the 3rd surface (flat surface) to the 3rd surface are air layers, and the surface spacing is 1.49652 mm, but the 3rd surface does not appear directly in FIG.

In the projector lens according to Example 3 shown in FIG. 9, the first lens group G 1 includes the first to 13th surfaces, the aperture stop S has the 14th surface, and the second lens group has the It is composed of 15 to 31 planes. Note that only the third surface is an aspheric surface, and this aspheric surface is represented by a conical coefficient k, C4, C6, ... This third surface is the surface on the projection surface side of the middle lens of L1 composed of three concave meniscus lenses in the first lens group G1. Further, the aspheric lens composed of the second surface and the third surface is made of resin (PMMA) having a thickness of 12.000 mm on the optical axis.

The total thickness on the optical axis from the 26th surface to the 32nd surface (object surface) is 68.096952 mm, which is expressed in terms of air-equivalent back focus (see Fig. 10). 5. 3 74 mm.

The focusing on the projection surface by the projector lens according to the third embodiment is because the method of extending only the three concave meniscus lenses L1 of the first lens group G1 suppresses aberration. preferable. Further, as shown in FIG. 10, the projector-one lens according to Example 3 does not satisfy the above conditional expression (2). This is because the first and second embodiments are designed to minimize the number of constituent lenses, while the third embodiment is designed to reduce the number of aspheric lenses. is there. However, Example 3 satisfies all the conditional expressions other than the conditional expression (2), so that the value of the maximum object height Y is 6.4 O mm, which is very small as compared with the conventional projector. Regardless, it is possible to project a good image with a large angle of view of 98.1 degrees while suppressing various aberrations. In addition, the back focus BF can be as large as 45.374 mm. Furthermore, the number of lenses in the first lens group is seven, and the number of lenses in the second lens group is eight, for a total of fifteen.There are more constituent lenses than in the other examples, but as described above, Since there is only one spherical lens, a projector lens can be constructed while minimizing the use of aspherical lenses.

Here, the corresponding values of the design conditional expressions (1) to (10) for the projector-one lens according to Examples 1 to 3 will be described with reference to FIG.

As shown in FIG. 10, in designing the first to third embodiments, the parameters in the conditional expression (10) from the lens design conditional expression (1) described above, that is, BF / Y (conditional expression (1 ): Air-equivalent back focus BF, maximum height Y of the object plane, dm / Y (Condition (2): Largest surface air gap dm in the lens group ahead of the aperture, dm, maximum height Y of the object plane), f ΖΤ (Conditional expression (3): focal length f of the entire projector lens, total length TL of the projector lens), A / B (Conditional expression (4): From the lens surface closest to the projection surface of the projector lens to the aperture stop S) Axial distance A, Axial distance from the lens surface closest to the object side of the projector lens to the aperture stop B), R / f (Conditional expression (5)): The concave of the first lens group closest to the projection surface Radius of curvature R of the meniscus lens on the object plane side, focal length of the entire projector lens f), | f L | Zd (Conditional expression (6): 3 sheets pasted together) Focal length f L of the concave lens at the center of the offset lens, thickness d of the three bonded lenses d), (| Δ ΐ | + | Δ 2 |) / 2 (conditional expression (7) _: 3 in order from the projection surface side E-line refractive index difference Δ 1, Δ 2), f 1 / f 2 (Condition (8): focal length f 1 of the first lens group, f 1 / f 2) Focal length ί 2), (| Δ ν ΐ | / | Δ ν 2 |) Ζ 2 (Conditional expression (9): Difference in Abbe number at the bonding surface of three bonded lenses in order from the projection surface side) Δ V 1, mm V 2), Β ¥ / f (Condition (10): Air-equivalent back focus BF, Focal length f of the entire projector lens f) are all conditional expressions (1) to (10) You can see that they are satisfied.

Specifically, in the projector lens of the present invention, as shown in FIG. 10, the focal length f is from 6.275 mm to 8.8 11 mm, and the knock focus BF is 39.760 mm. From 54.44 7mm, the angle of view is 83.4 degrees, the angle 91.3 degrees, BF / f of conditional expression (10) is 5.362 Was. Here, in order to compare with the projector lens according to the present invention, the values of the conventional projector lens described in Patent Document 1 are as follows. The focal length f is 12.53 mm from 12.37 mm, and the knock focus BF Is 5 2.27 mm to 54.3 1 mm, angle of view 2 ω force 80.1 8 degrees force to 8 1.94 degrees, Β F / f is 4.18 force to 4.39 there were.

As a result, B FZ f of the conditional expression (10) of the present embodiment is about 5.4 to 7.2 as described above, which is a larger value than the conventional one. As a result, despite the fact that the focal length f of the projector lens is shorter than before, the air-equivalent back focus BF can be made sufficiently longer than before, and the color shading on the projection surface can be kept sufficiently small. Furthermore, it was possible to suppress various aberrations while suppressing color shading.

As described above, the projector lens of the present invention has a shorter projection distance, Suitable for large screen projection. Also, it was possible to provide a projector lens for a large-screen projector with high image quality in which various aberrations were corrected well. Furthermore, the projector lens of the present invention has a short focal length and a wide angle, and can suppress various aberrations, while maintaining the same performance in the back focus as compared with the conventional projector lens. As described above, according to the present invention, a projector lens having high image quality and high magnification can be realized.

(Example 4)

Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a plan view of a projector device using the projector lens of the present invention described above. As shown in FIG. 11, in the projector device according to the fourth embodiment, first, the light source light emitted from the light source 11 is converted into single polarized light by the polarization conversion illumination device 12. Although the configuration of the polarization conversion illuminating device 12 is not shown, for example, it is formed of an optical system including a fly-eye lens, and a light source light homogenizing member that homogenizes light from the light source light, and a polarization direction of the homogenized light And a condenser lens that superimposes and illuminates a single polarized light on a light valve described later.

The single polarized light emitted from the polarization conversion illumination device 12 is color-separated into three color lights of R (red) light, G (green) light, and B (blue) light by a color separation optical system. The color separation optical system according to the present embodiment has a dike opening mirror 13 RG that reflects R and G light and transmits B light, and a characteristic that reflects B light and transmits R and G light. A cross dichroic mirror 13 in which the dichroic mirrors 13 B are orthogonally arranged, and a dichroic mirror 16 having the property of reflecting G light and transmitting R light. The single polarized light is color-separated into the mixed light of the R light and the G light and the B light by the cross dichroic mirror 13. Here, the mixed light of the color-separated R light and G light is deflected in the traveling direction by the deflecting mirror 14, and is reflected by the dichroic mirror 16 having the characteristic of reflecting the G light and transmitting the R light. Incident light is separated into R light and G light. Then, the separated R light and G light are respectively incident on the wire-dar- ried polarizers 17R and 17G arranged obliquely with respect to the optical axis.

On the other hand, the traveling direction of the color-separated B light is deflected by the deflecting mirror 15 and is incident on a wire-darried polarizer 17B arranged obliquely with respect to the optical axis.

Here, the wire grid polarizers 17R, 17G, and 17B are described as follows: a parallel flat plate on which metal wires having a width shorter than the wavelength are arranged at equal intervals. Yes, it is arranged so that the surface on which the wire is formed is directed to the side where the color separation light is incident. Therefore, each of the wavelength-separated color lights is incident on the wire formation surface.

Each of the color lights reflected by the above-mentioned wire-shadow is incident on each of the light-vane lights 18 R, 18 G, and 18 B for each color light, and is input to the light valve for each color light. The light is emitted by receiving a modulation action according to the image signal. Each color light modulated by the light valve is incident on a Wire-Darid polarizer 17R, 17G, 17B, and the modulated light contributing to image formation is a wire-grid polarizer. 7R, 17G, and 17B are transmitted and extracted, and the unmodulated light that does not contribute to image formation is reflected by the wire grid polarizers 17R, 17G, and 17B toward the light source. Discarded.

The modulated light of each color light transmitted through the wire grid polarizers 17 R, 17 G, and 17 B is incident on the cross dichroic prism 20, where the colors are synthesized, and is screened by the projector lens 22. Is projected to Note that the projector lens 22 is a projector lens according to the present invention, and is, for example, a single projector lens of the second embodiment. In the above, the modulated light passes through the wire grid polarizers 17R, 17G, and 17B, so that each modulated light also passes through the parallel plate on which the wire grid is formed. . Since the parallel plates are arranged obliquely with respect to the optical axis, each light transmitted through the wire grid polarizers 17R, 17G, and 17B has a predetermined amount of coma aberration. Component and astigmatism component will be included.

Therefore, in the fourth embodiment, the coma aberration generated by the parallel plates of the above-mentioned wire-darried polarizers 17R, 17G, and 17B is reduced by the wire-grid polarizers 17R, 17G, and 17G. The correction is performed by parallel plate-shaped aberration correction members 19R, 19G, and 19B disposed between 17B and the cross dichroic prism 20 that is a color combining optical system. Further, the astigmatism generated by the parallel plates of the wire-darried polarizers 17 R, 17 G, and 17 B is disposed between the cross-dike opening stroke bomb 20 and the projector lens 22. Corrected by cylindrical lens 21.

Therefore, the wire grid polarizer 17 (17R, 17G, 17B) and the coma are located between the light valve 18 and the rearmost lens rearmost surface of the projector lens 22. A parallel flat plate 19 for correction, a cross dichroic prism 20 and a cylindrical lens 21 are arranged. The projector lens 22 according to the present invention can arrange all of these members, and has a sufficiently long back focus.

(Example 5)

Hereinafter, a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 12 shows another embodiment of the projector device of the present invention, which is different from the fourth embodiment. In the projector device shown in FIG. 12, the reference numerals corresponding to the members are the same as those of the projector device of the fourth embodiment shown in FIG. As shown in FIG. 12, in the projector device according to the fifth embodiment, the cylindrical lens 21 is arranged at the position of the stop 22 c of the projector lens 22. In all of the projector lenses according to the first to third embodiments, spaces are provided before and after the stop. In each of the embodiments, the cylindrical lens 21 can be disposed at the position of the stop. In such an arrangement, it is not necessary to secure an arrangement space for the cylindrical lens 21 in the space between the light valve 18 and the rearmost lens rearmost surface of the projector lens 22.

Therefore, according to the projector device according to the fifth embodiment, it is possible to provide a projector device having sufficient back focus and capable of projecting an image even in a projector using a gauge lid as an analyzer.

The present invention as described above is not limited to the above-described embodiment, and can be appropriately modified without departing from the gist of the present invention. ,

Claims

The scope of the claims

1. In order from the projection side,

A first lens group having at least two negative meniscus lenses having a convex surface facing the projection surface side and having a positive refractive power;

A second lens group having a positive refractive power;

And an aperture stop disposed between the first lens group and the second lens group.

The first lens group includes at least one aspheric lens, and when an air-equivalent back focus is B F and a maximum object height is Y,

5.5 BF / Y <15.0

Projector Ichiren X that satisfies the following.

2. When the maximum object height is Y and the largest lens surface interval of the first lens group is dm,

8.0 <d mZ Y <15.0

2. The projector lens according to claim 1, wherein the following is satisfied.

3. The second lens group includes two or more cemented lenses, where f is the focal length of the entire lens system and TL is the total length of the lens system. 3. The projector lens according to claim 1, wherein the projector lens satisfies condition 1.

4. The first lens group includes at least one concave meniscus lens made of glass having an Abbe number of 57 or more,

The second lens group includes one glass lens having an Abbe number of 70 or more. Including

When the distance on the optical axis from the lens surface closest to the projection side to the aperture stop is A, and the distance on the optical axis from the lens surface closest to the object surface to the aperture stop is B,

1.0 <A / B <4.0

The projector-one lens according to any one of claims 1 to 3, which satisfies the following.

5. The first lens group includes two or more glass concave meniscus lenses having an Abbe number of 65 or more,

The second lens group includes three cemented lenses including a low dispersion glass having an Abbe number of 70 or more and a high refractive index glass having a refractive index of 1.7 or more, and a concave lens at the center of the three cemented lenses. When the focal length is f L and the composite thickness of the three cemented lenses is d,

0.2 <I f L I / d <7.0

The projector-lens according to any one of claims 1 to 4, wherein the following is satisfied.

6. The three-piece bonded lens is composed of a convex lens, a concave lens, and a convex lens in order from the projection surface side,

When the refractive index difference of the e-line on the bonding surface is Δ 1, Δ 2 in order from the projection surface side,

0.2 <(| Δ ΐ | + | Δ 2 |) / 2

The projector-one lens according to claim 5, wherein the following condition is satisfied.

7. In the second lens group, it is necessary that at least one aspherical surface is provided. A projector-one lens according to any one of claims 1 to 6, wherein: When the focal length of the first lens group is f 1 and the focal length of the second lens group is ί2,

0. 5 <ί 1 / ί 2 <3.0.

The projector-lens according to any one of claims 1 to 7, wherein the following is satisfied. When the radius of curvature of the surface on the object surface side of the negative mesas lens closest to the projection surface is R, and the focal length of the entire lens system is f,

R / f <8.0

The projector-lens according to any one of claims 1 to 8, wherein the following is satisfied. 1 0. Light source and

A wavelength separation member that separates light source light emitted from the light source into a plurality of color lights;

An image forming element that receives the plurality of color lights passing through the wavelength separation member and forms an image for each of the color lights;

A wire element for separating light contributing to image formation and light not contributing to image formation for each color light,

A synthesizing optical system for synthesizing light that contributes to image formation, out of the respective color lights passing through the wire grid element,

10. A projector apparatus, comprising: the projector lens according to claim 1, which projects the light combined by the combining optical system onto a screen.