JP2010113150A - Projection zoom lens and projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type zoom lens that is compact and composed of two-groups having five lenses, in which spherical aberration, in particular, is more satisfactorily corrected. <P>SOLUTION: The projection zoom lens includes, in order from the magnifying side, a first group G<SB>1</SB>of negative refractive power, a second group G<SB>2</SB>of positive refractive power, a cover glass 2 and a DMD (Digital Micromirror Device) 1. The first group G<SB>1</SB>is composed of only first lens L<SB>1</SB>, which is a negative meniscus and the convex face of which is directed toward the magnifying side. The second group G<SB>2</SB>has, in order from the magnifying side, a positive second lens L<SB>2</SB>, a third lens L<SB>3</SB>, which is directed toward the magnifying side, a negative fourth lens L<SB>4</SB>, and a positive fifth lens L<SB>5</SB>. For zooming from the wide-angle end to the tele-photo end, the first group G<SB>1</SB>moves from the magnifying side toward the reducing side, and the second group G<SB>2</SB>moves from the reducing side toward the magnifying side. In addition, the projection zoom lens satisfies conditional expression (1):-0.25<R3r/f45, wherein R3r is the radius of curvature of the reducing side face of the third lens L<SB>3</SB>and f45 is the combined focal length of the fourth and fifth lenses L<SB>4</SB>and L<SB>5</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projection zoom lens mounted on a projection display device and the projection display device thereof, and more particularly to a compact suitably used for a projection display device employing a DMD (digital micromirror device) as a light valve. The present invention relates to a projection zoom lens and a projection display device thereof.

  In recent years, in addition to liquid crystal display devices, projection projector devices (projection display devices) using DMD display devices have come to be used. DMD controls the reflection direction of light from the light source using a highly reflective rectangular micro mirror that can change the inclination in the range of about 10 degrees or more according to the input video signal, Only the reflected light is focused on the screen, and the image can be projected. This is done, for example, by arranging millions or more of mirrors vertically and horizontally on a substrate and independently digitally controlling each mirror, and each mirror corresponds to one pixel in an image.

  In addition, unlike a liquid crystal display device, the DMD does not need to polarize the irradiation light, so there is little loss in the amount of light and it is excellent in terms of accuracy of gradation expression. Therefore, in a projection projector apparatus using DMD having such advantages, a projection zoom lens having good lens characteristics is required so that a clear and highly accurate image can be obtained according to DMD. .

  In recent years, projection projector apparatuses are particularly required to be compact, and accordingly, a projection zoom lens having a simpler and more compact configuration is also required.

  As a zoom lens for projection having a two-group five-lens configuration that can be easily and compactly corrected for various aberrations, a lens described in Patent Document 1 is known.

JP 2008-107798 A

  However, although the lens described in Patent Document 1 has a simple and compact configuration of 5 elements in 2 groups, a projection zoom lens for a projection projector apparatus using DMD includes spherical aberration. There was room for improvement in terms of correction of various aberrations.

  The present invention has been made in view of the above circumstances, and in a simple and compact two-group five-element configuration type, particularly a zoom lens for projection and projection capable of better correcting various aberrations including spherical aberration. An object of the present invention is to provide a mold display device.

The projection zoom lens of the present invention is
A projection zoom lens in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the magnification side,
The first lens group is composed of a first lens composed of a single negative meniscus lens having a convex surface on the enlargement side,
The second lens group includes, in order from the magnification side, a second lens composed of a positive lens, a third lens composed of a positive meniscus lens having a convex surface facing the magnification side, a fourth lens composed of a negative lens, and a positive lens. Consists of four fifth lenses,
During zooming, the first lens group and the second lens group are both configured to move in the optical axis direction,
The following conditional expression (1) is satisfied.
-0.25 <R3r / f45 (1)
here,
R3r: radius of curvature of the reduction side surface of the third lens f45: combined focal length of the fourth lens and the fifth lens It is preferable that the following conditional expression (2) is satisfied.
0.75 <R3f / D35 <1.00 (2)
here,
R3f: radius of curvature of the enlargement-side surface of the third lens D35: distance from the enlargement-side surface vertex of the third lens to the reduction-side surface vertex of the fifth lens

Moreover, it is preferable that the following conditional expression (3) is satisfied.
N5> 1.77 (3)
here,
N5: refractive index of the fifth lens with respect to d-line

  In the second lens group, it is preferable that the fifth lens has a highest refractive index.

Moreover, it is preferable that the following conditional expression (4) is satisfied.
ν1 <50.0 (4)
here,
ν1: Abbe number of the first lens with respect to the d-line

  Furthermore, a projection display device according to the present invention includes a light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, and a projection zoom lens according to the present invention. The light beam is modulated by the light valve and projected onto the screen by the projection zoom lens.

  According to the projection zoom lens of the present invention, in order from the enlargement side, the first lens group having a negative refractive power is configured by one lens, and the second lens group having a positive refractive power is formed by four lenses. The zoom lens includes a lens, and is configured such that both the first lens group and the second lens group move in the optical axis direction at the time of zooming. Thus, a simple and compact zoom lens having two groups and five elements can be obtained.

  Further, by disposing the first lens group having negative refractive power on the screen side, a retrofocus type can be achieved and a wide angle can be achieved.

  The second lens group includes, in order from the magnifying side, a second lens made of a positive lens, a third lens made of a positive meniscus lens having a convex surface facing the magnifying side, a fourth lens made of a negative lens, and a positive lens. By satisfying the conditional expression (1), the axial light beam is perpendicular to the reduction-side surface of the positive meniscus lens with the convex surface facing the enlargement side. It is possible to make the light incident at an angle close to that of the lens, whereby the occurrence of spherical aberration can be significantly suppressed.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The projection zoom lens of the embodiment shown in FIG. 1 (representing the lens of Example 1 as a representative) has, in order from the enlargement side, a first lens group G ₁ having a negative refractive power and a positive refractive power. The second lens group G ₂ , the cover glass (filter part) 2, and the DMD 1 are disposed. In the figure, X represents the optical axis.

Here, the first lens group G ₁ is composed of only the first lens L ₁ composed of one negative meniscus lens having a convex surface facing the magnification side, a second lens group G ₂ includes, in order from the magnification side, a positive lens A second lens L ₂ , a third lens L _{3 made of} a positive meniscus lens having a convex surface facing the enlargement side, a fourth lens L ₄ which is a negative lens, and a fifth lens L ₅ which is a positive lens. Are arranged.

The projection zoom lens according to the present embodiment, by moving the first lens group G ₁ and the second lens group G _2, and is configured to have a zoom function. Here, upon zooming from the wide-angle end to the telephoto end, the first lens group G ₁ is configured to move continuously toward the reduction side from the magnification side, a second lens group G ₂ is the reduction side It is comprised so that it may move continuously toward the expansion side.

Here, the second lens L ₂ constituting the second lens group G ₂ is a biconvex lens in many embodiments, but can be a positive lens having other shapes (implementation). Example 4 is a positive meniscus lens having a convex surface on the reduction side).

In addition, the fourth lens L ₄ constituting the second lens group G ₂ is a biconcave lens in each embodiment, but may be a negative lens having other shapes. The five lens L ₅ is a biconvex lens in each embodiment, but may be a positive lens having another shape.

In the second lens group G _2, the fifth lens L ₅ of the four lenses, it is possible to use the largest material having a refractive index, preferable from the viewpoint of suppressing the spherical aberration.

In addition, the projection zoom lens of the present embodiment satisfies the following conditional expression (1), and in a more preferable aspect, satisfies the following conditional expressions (2), (3), and (4).
-0.25 <R3r / f45 (1)
0.75 <R3f / D35 <1.00 (2)
N5> 1.77 (3)
ν1 <50.0 (4)
here,
R3R: a third lens _{L 3} on the reduction side of the surface of the curvature radius of f45: composite focal length of the fourth lens _{L 4} and the fifth lens _{L 5} R3f: curvature of the enlargement side surface of the third lens _{L 3} radius D35: first third lens _{L 3} distance from the enlarged side vertices to reduce side vertex of the fifth lens _{L 5} N5: Abbe number of the first lens _{L 1} of the d-line refractive index ν1 the d-line of the fifth lens _{L 5}

Next, the technical significance of the conditional expressions (1) to (4) will be described.
Condition (1) specifies the fourth lens L ₄ with respect to the composite focal length f45 of the fifth lens L _5, the value of the ratio of the radius of curvature R3r the reduction side surface of the third lens L _3, by satisfying the conditional expression (1), to the surface on the reduced side of the third lens L _3, it is possible to enter the axial light beam in the near-vertical angle, thereby greatly suppressing the occurrence of spherical aberration can do.

In addition, such an effect can be made more favorable by satisfying the following conditional expression (1 ′) instead of the conditional expression (1).
−0.25 <R3r / f45 <0.25 (1 ′)

Further, such an effect can be further improved by satisfying the following conditional expression (1 ″) instead of the conditional expression (1 ′).
−0.20 <R3r / f45 <0.20 (1 ″)

Further, the conditional expression (2), from the enlarged side vertex of the third lens L ₃ to the distance D35 to the reduced side vertex of the fifth lens L _5, the curvature radius R3f the magnification side surface of the third lens L ₃ defines a value of the ratio, by satisfying the conditional expression (2), in terms of expansion of the third lens L _3, it is possible to emit the axial principal ray at a nearly vertical angle, Thereby, the occurrence of coma and astigmatism can be significantly suppressed.

In addition, such an effect can be made more favorable by satisfying the following conditional expression (2 ′) instead of the conditional expression (2).
0.75 <R3f / D35 <0.95 (2 ′)

FIG. 13 shows the above-described action by satisfying conditional expression (1) and the above-described action by satisfying conditional expression (2) in the projection zoom lens according to the present embodiment, respectively. That is, by satisfying the conditional expression (1), axial light beam (indicated by the solid line), the third lens L ₃ on the reduction side surface L3R, has been shown how the incident at an angle close to verticality in addition, by satisfying the conditional expression (2), the off-axis principal ray (indicated by the broken line), from the surface L3F the third lens L ₃ on the enlargement side, shows a state of emitting at an angle close to verticality ing.

Further, the conditional expression (3) is intended to define a refractive index at the d-line of the material constituting the fifth lens L _5, by satisfying the conditional expression (3), the fifth lens L ₅ The curvature of the lens surface can be relaxed and the occurrence of spherical aberration can be suppressed.

In addition, such an effect can be made more favorable by satisfying the following conditional expression (3 ′) instead of the conditional expression (3).
N5> 1.80 (3 ')

The conditional expression (4) defines the Abbe number of the material of the first lens L ₁ with respect to the d-line. By satisfying the conditional expression (4), the green color at the periphery of the image circle is determined. The tendency that the lateral chromatic aberration of the blue light B with respect to the light G appears on the + side can be suppressed.

  Next, an embodiment of a projection display device according to the present invention will be briefly described. FIG. 14 is a schematic configuration diagram of a projection display apparatus according to this embodiment.

  As shown in FIG. 14, the light beam emitted from the light source 101 is selectively converted into each light of the three primary color lights (R, G, B) in time series by a color wheel (not shown), and the illumination optical system 102 The DMD 103 is irradiated with a uniform light amount distribution in a cross section perpendicular to the optical axis of the light beam. In this DMD 103, modulation switching to the color light is performed in accordance with the change of the color of the incident light, and the projection light appropriately modulated by the DMD 103 enters the projection zoom lens 104, and finally the screen. 105 is reached.

  The projection display device shown in FIG. 14 shows one embodiment of the present invention, and various modifications can be made. For example, instead of providing a single-plate DMD, the RGB colors may be modulated simultaneously by three DMDs corresponding to each color light. In this case, a color separation / synthesis prism (not shown) is disposed between the projection zoom lens 104 and the DMD 103.

  Note that another light valve (for example, a transmissive liquid crystal display element or a reflective liquid crystal display element) may be used instead of the DMD.

  Hereinafter, the projection zoom lens of the present invention will be further described with reference to specific examples.

<Example 1>
FIG. 1 shows a schematic configuration of the projection zoom lens according to the first embodiment. The projection zoom lens includes, in order from the magnification side, a first lens group G ₁ having a negative refractive power, and by disposing the second lens group G ₂ having a positive refractive power.

Here, the first lens group G ₁ is composed of only the first lens L ₁ composed of one negative meniscus lens having a convex surface facing the magnification side, a second lens group G ₂ includes, in order from the magnification side, both A second lens L ₂ that is a convex lens, a third lens L ₃ that is a positive meniscus lens having a convex surface facing the enlargement side, a fourth lens L ₄ that is a biconcave lens, and a fifth lens L ₅ that is a biconvex lens are arranged. Do it. Note that the fourth lens L ₄ fifth lens L ₅ is formed by being disposed in close proximity.

Further, during zooming from the wide-angle end to the telephoto end, the first lens group G ₁ is configured to move continuously toward the reduction side from the magnification side, a second lens group G ₂ includes, from the reduction side It is configured to move continuously toward the enlargement side.

  The radius of curvature R (mm) of each lens surface of the projection zoom lens, the center thickness of each lens, and the air spacing between the lenses (hereinafter collectively referred to as the axial top surface spacing) D (mm), Table 1 shows the values of the refractive index Nd and the Abbe number νd in the d-line. The numbers in the table represent the order from the enlarged side (the same applies to the following examples). In the upper part of Table 1, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Further, according to the projection zoom lens of Example 1, as shown in Table 7, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′) ) Is satisfied.

  FIG. 7 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the projection zoom lens of Example 1. FIG. The spherical aberration diagram shows the aberrations for each wavelength of 460 nm, 550 nm, and 620 nm, and the astigmatism diagram shows the aberrations for the sagittal image surface and the tangential image surface (FIGS. 8 to 8). 12 is the same).

  As is clear from these aberration diagrams, according to the projection zoom lens of Example 1, each aberration can be corrected extremely well.

<Example 2>
FIG. 2 shows a schematic configuration of the projection zoom lens according to the second embodiment. In the present embodiment, descriptions overlapping with those in the first embodiment are omitted.

  The lens configuration and operational effects of the projection zoom lens according to Example 2 are substantially the same as those of Example 1.

  Table 2 shows the values of the radius of curvature R (mm) of each lens surface of this projection zoom lens, the distance D (mm) between the axial top surfaces of each lens, and the refractive index N and the Abbe number ν for each lens d-line. In the upper part of Table 2, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Also, according to the projection zoom lens of Example 2, as shown in Table 7, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′) ) Is satisfied.

  FIG. 8 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the projection zoom lens of Example 2. FIG.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 2, each aberration can be corrected extremely well.

<Example 3>
FIG. 3 shows a schematic configuration of the projection zoom lens according to the third embodiment. In the present embodiment, descriptions overlapping with those in the first embodiment are omitted.

  The lens configuration and operational effects of the projection zoom lens according to Example 3 are substantially the same as those of Example 1.

  Table 3 shows the values of the radius of curvature R (mm) of each lens surface of the projection zoom lens, the axial top surface distance D (mm) of each lens, and the refractive index N and Abbe number ν for each lens d-line. In the upper part of Table 3, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Further, according to the projection zoom lens of Example 3, as shown in Table 7, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′) ) Is satisfied.

  FIG. 9 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the projection zoom lens of Example 3.

  As is clear from these aberration diagrams, according to the projection zoom lens of Example 3, each aberration can be corrected extremely well.

<Example 4>
FIG. 4 shows a schematic configuration of the projection zoom lens according to the fourth embodiment. In the present embodiment, descriptions overlapping with those in the first embodiment are omitted.

Lens configuration and effects of the projection zoom lens according to Example 4 is the ones with substantially the same manner as in Example 1, second lens L ₂ is, it is a positive meniscus lens having a convex surface facing the reduction side This is different from that of the first embodiment.

  Table 4 shows the values of the radius of curvature R (mm) of each lens surface of this projection zoom lens, the distance D (mm) between the axial top surfaces of each lens, and the refractive index N and Abbe number ν of each lens at the d-line. In the upper part of Table 4, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Further, according to the projection zoom lens of Example 4, as shown in Table 7, the conditional expressions (1) to (4), (1 ′), (1 ″), and (2 ′) are satisfied. Yes.

  FIG. 10 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the zoom lens for projection according to the fourth embodiment.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 4, each aberration can be corrected extremely well.

<Example 5>
FIG. 5 shows a schematic configuration of the projection zoom lens according to the fifth embodiment. In the present embodiment, descriptions overlapping with those in the first embodiment are omitted.

  The lens configuration and operational effects of the projection zoom lens according to Example 5 are substantially the same as those of Example 1.

  Table 5 shows the values of the radius of curvature R (mm) of each lens surface of the projection zoom lens, the axial top surface distance D (mm) of each lens, and the refractive index N and Abbe number ν of each lens at the d-line. In the upper part of Table 5, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Also, according to the projection zoom lens of Example 5, as shown in Table 7, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′) ) Is satisfied.

  FIG. 11 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the projection zoom lens of Example 5. FIG.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 5, each aberration can be corrected extremely well.

<Example 6>
FIG. 6 shows a schematic configuration of the projection zoom lens according to Example 6. In the present embodiment, descriptions overlapping with those in the first embodiment are omitted.

  The lens configuration and operational effects of the projection zoom lens according to Example 6 are substantially the same as those of Example 1.

  Table 6 shows the values of the radius of curvature R (mm) of each lens surface of the projection zoom lens, the axial top surface distance D (mm) of each lens, and the refractive index N and Abbe number ν for each lens d-line. In the upper part of Table 6, the focal length f, the back focus distance Bf, FNo. The value of the angle of view 2ω is shown.

  Further, according to the projection zoom lens of Example 6, as shown in Table 7, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′) ) Is satisfied.

  FIG. 12 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the projection zoom lens according to Example 6.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 6, it is possible to correct each aberration extremely well.

1 is a schematic diagram showing a configuration of a projection zoom lens according to Example 1 of the present invention. FIG. Schematic showing the configuration of a projection zoom lens according to Example 2 of the present invention. Schematic showing the configuration of a projection zoom lens according to Example 3 of the present invention. Schematic showing the configuration of a projection zoom lens according to Example 4 of the present invention. Schematic showing the configuration of a projection zoom lens according to Example 5 of the present invention. Schematic showing the configuration of a projection zoom lens according to Example 6 of the present invention. Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 1. Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the projection zoom lens of Example 2. Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the projection zoom lens of Example 3 Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the projection zoom lens of Example 4. Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the projection zoom lens of Example 5 Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) of the projection zoom lens of Example 6. FIG. 7 is a conceptual diagram showing an action of satisfying conditional expressions (1) and (2) in the projection zoom lens according to the embodiment of the present invention. Schematic configuration diagram of a projection display device using the projection zoom lens of the present invention

Explanation of symbols

L ₁ ~L ₅ lens _G 1 ~G ₂ lens group X optical axes 1,103 DMD
2 Cover glass (filter part)
101 a light source 102 faces the reduction side of the expansion-side surface L3R third lens _{L 3} of the illumination optical system 104 projection zoom lens 105 screen L3F third lens _{L 3}

Claims (6)

A projection zoom lens in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the magnification side,
The first lens group is composed of a first lens composed of a single negative meniscus lens having a convex surface on the enlargement side,
The second lens group includes, in order from the magnification side, a second lens composed of a positive lens, a third lens composed of a positive meniscus lens having a convex surface facing the magnification side, a fourth lens composed of a negative lens, and a positive lens. Consists of four fifth lenses,
During zooming, the first lens group and the second lens group are both configured to move in the optical axis direction,
A projection zoom lens satisfying the following conditional expression (1):
-0.25 <R3r / f45 (1)
here,
R3r: radius of curvature of the reduction side surface of the third lens f45: composite focal length of the fourth lens and the fifth lens The projection zoom lens according to claim 1, wherein the following conditional expression (2) is satisfied.
0.75 <R3f / D35 <1.00 (2)
R3f: radius of curvature of the enlargement-side surface of the third lens D35: distance from the enlargement-side surface vertex of the third lens to the reduction-side surface vertex of the fifth lens 3. The projection zoom lens according to claim 1, wherein the following conditional expression (3) is satisfied.
N5> 1.77 (3)
here,
N5: refractive index of the fifth lens with respect to d-line   4. The projection zoom lens according to claim 1, wherein a refractive index of the fifth lens is the largest in the second lens group. 5. The projection zoom lens according to claim 1, wherein the following conditional expression (4) is satisfied.
ν1 <50.0 (4)
here,
ν1: Abbe number of the first lens with respect to the d-line   A light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, and a projection zoom lens according to any one of claims 1 to 5, wherein the light beam from the light source A projection type display apparatus, wherein the light valve modulates light and projects onto a screen by the projection zoom lens.

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