JP2014021309A - Compact projection lens and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact projection lens which has high optical performance and light resistance for satisfactorily correcting chromatic aberrations with a smaller number of lenses though having no cemented lenses, and a projector including the same.SOLUTION: A projection lens LN substantially telecentric on the reduction side includes, in order from the enlargement side, a first lens L1 having a meniscus shape convex to the enlargement side, a second lens L2 having a meniscus shape convex to the enlargement side and having a negative power, a third lens L3 having a negative power, a fourth lens L4 being convex to the reduction side and having a positive power, and a fifth lens L5 being convex to the reduction side and having a positive power. Faces facing each other of the third and fourth lenses L3 and L4 are aspherical surfaces having different surface shapes, and at least one of positive lenses closer to the reduction side than the fourth lens L4 satisfies conditional expressions 0.66<0.0018×Vd+P and 60<Vd (where Vd represents an Abbe number relating to the d line, P=(Ng-NF)/(NF-NC) is true, and Ng, NF, and C represent refractive indexes at the g line, the F line, and C line respectively).

Description

  The present invention relates to a projection lens and a projector, for example, a small projector using a laser light source for illumination, and a small projection lens suitable for the projector.

  With the widespread use of mobile devices, the demand for small and light projection devices that can be mounted on mobile devices has increased, and various types of small projection lenses used therefor have been proposed (see, for example, Patent Documents 1 to 4). .) Moreover, although the apparatus which uses a laser light source for illumination has increased, in the case of a small projection lens, since it may condense locally with a big light quantity, high light resistance is calculated | required.

JP 2010-181653 A JP 2010-249946 A JP 2010-249947 A JP 2011-170309 A

  In any of the projection lenses described in Patent Documents 1 to 4, a cemented lens is used. Since a resin bonding material is used for bonding the lens, the light resistance is lowered when a bonded lens is used. However, it is difficult to sufficiently correct chromatic aberration with a small number of lenses without using a cemented lens.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a compact optical system having high optical performance and light resistance that can satisfactorily correct chromatic aberration with a small number of lenses without a cemented lens. The object is to provide a projection lens and a projector including the projection lens.

To achieve the above object, a projection lens according to a first aspect of the present invention is a projection lens that is substantially telecentric on the reduction side, and in order from the enlargement side, a first lens having a convex meniscus shape on the enlargement side, and an enlargement side A negative power second lens having a convex meniscus shape, a negative power third lens, a positive positive power fourth lens on the reduction side, and a positive positive power fifth lens on the reduction side, And the third lens and the fourth lens are opposite aspherical surfaces, and at least one of the positive lenses existing on the reduction side of the fourth lens has the following conditional expression (1 ) And (2) are satisfied.
0.66 <0.0018 × Vd + P (1)
60 <Vd (2)
However,
Vd: Abbe number for the d line,
P = (Ng-NF) / (NF-NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
It is.

A projection lens according to a second invention is characterized in that, in the first invention, the following conditional expressions (3) and (4) are satisfied.
1.2 <fp / f <2.5 (3)
2.5 <| f1 | / f (4)
However,
fp: the combined focal length of the lens group consisting of all the lenses located on the reduction side of the fourth lens,
f1: focal length of the first lens,
f: focal length of the entire system,
It is.

A projection lens according to a third aspect of the invention is characterized in that, in the first or second aspect of the invention, the following conditional expression (5) is satisfied.
-2 <f3 / f4 <-0.5 (5)
However,
f3: focal length of the third lens,
f4: focal length of the fourth lens,
It is.

A projection lens according to a fourth aspect of the invention is characterized in that, in any one of the first to third aspects of the invention, the following conditional expression (6) is satisfied.
T34 / f <0.05 (6)
However,
T34: air distance on the optical axis between the third lens and the fourth lens,
It is.

A projection lens according to a fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the following conditional expressions (7) and (8) are satisfied.
0.4 <Rf / Y ′ <0.8 (7)
1 <Rr / Y ′ <1.25 (8)
However,
Rf: effective radius of the most magnified lens surface,
Rr: effective radius of the lens surface closest to the reduction side,
Y ′: reduced-side image circle radius,
It is.

  A projection lens according to a sixth invention is characterized in that, in any one of the first to fifth inventions, an aperture stop is provided between the second lens and the third lens.

  The projection lens of a seventh invention is characterized in that, in any one of the first to sixth inventions, the glass transition temperature of all the lens materials is 250 ° C. or higher.

  According to an eighth aspect of the invention, there is provided an image display device for displaying an image, a light source, an illumination optical system for guiding light from the light source to the image display device, and an image displayed on the image display device on a screen surface. And a projection lens according to any one of the first to seventh aspects of the present invention for performing enlarged projection.

  According to the present invention, since the opposite surfaces of the third and fourth lenses are aspherical surfaces, a material satisfying a predetermined condition is used for the positive lens existing on the reduction side of the fourth lens. Even without a lens, it is possible to correct chromatic aberration satisfactorily with a small number of lenses. Therefore, it is possible to realize a compact projection lens having high optical performance and light resistance and a projector including the same.

The optical path figure of 1st Embodiment (Example 1). The optical path figure of 2nd Embodiment (Example 2). FIG. 6 is an aberration diagram of Example 1. FIG. 6 is an aberration diagram of Example 2. The schematic diagram which shows the schematic structural example of the projector carrying a projection lens.

Hereinafter, a projection lens, a projector, and the like according to the present invention will be described. The projection lens according to the present invention is a substantially telecentric projection lens on the reduction side, and in order from the magnification side, a first lens having a convex meniscus shape on the magnification side, and a negative power having a convex meniscus shape on the magnification side A second lens having a negative power, a fourth lens having a positive power convex on the reduction side, and a fifth lens having a positive power convex on the reduction side (power: focal length) The quantity defined by the reciprocal). Further, the facing surfaces of the third lens and the fourth lens are aspherical surfaces having different surface shapes, and at least one of positive lenses existing on the reduction side of the fourth lens has the following conditional expression (1 ) And (2).
0.66 <0.0018 × Vd + P (1)
60 <Vd (2)
However,
Vd: Abbe number for the d line,
P = (Ng-NF) / (NF-NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
It is.

  With the above configuration, a compact and high-performance optical system can be realized. For example, in order from the magnifying side, a first lens having a convex meniscus shape on the magnifying side, a second lens having a negative meniscus shape on the magnifying side, a third lens having a negative power, and a convex lens on the reducing side By including a fourth lens with positive power and a fifth lens with positive power convex on the reduction side, it is possible to provide a configuration with little power on the enlargement side, thereby enabling distortion, curvature of field, etc. This configuration focuses on correcting aberrations. Further, by making the surfaces of the third and fourth lenses facing each other aspherical, it is possible to correct lateral chromatic aberration at a high order.

  The effect of correcting chromatic aberration is lower on the enlargement side than the third lens, and a relatively strong positive power is required on the reduction side to ensure telecentricity on the reduction side, so that it is closer to the reduction side than the fourth lens. If a negative lens is arranged, the number of lenses increases and the compactness is impaired. Therefore, at least one of the positive lenses existing on the reduction side with respect to the fourth lens satisfies both the conditional expression (1) that defines the anomalous dispersion and the conditional expression (2) that defines the Abbe number. By configuring, it is possible to correct chromatic aberration satisfactorily without using a cemented lens. In other words, power is given to the reduction side in order to secure substantially telecentricity to the reduction side, but it exists on the reduction side from the fourth lens in order to correct chromatic aberration (particularly axial chromatic aberration) caused by the power. A material that satisfies the conditional expressions (1) and (2) is used for at least one of the positive lenses. Since the positive lens existing on the reduction side of the fourth lens has a relatively strong power, chromatic aberration (especially longitudinal chromatic aberration) can be sufficiently corrected if the conditional range (1) or (2) is not satisfied. Disappear.

  In the cemented lens, the resin bonding material used for bonding the lenses is likely to be deteriorated by light (particularly laser light), and peeling at the bonded surface is likely to occur due to the difference in the linear expansion coefficient of the bonded lenses. For this reason, when a cemented lens is used, light resistance is lowered. However, it is difficult to sufficiently correct chromatic aberration with a small number of lenses without using a cemented lens. In the projection lens according to the present invention, as described above, the chromatic aberration correction effect can be obtained by the configuration satisfying the conditional expressions (1) and (2), and as a result, the number of cemented lenses can be reduced or omitted. High light resistance can be obtained with a small number of lenses.

  As described above, according to the characteristic configuration of the projection lens according to the present invention, the opposing surfaces of the third and fourth lenses are aspherical surfaces, and a material satisfying a predetermined condition is present on the reduction side from the fourth lens. Since the lens is used for the lens, it is possible to satisfactorily correct chromatic aberration with a small number of lenses even without a cemented lens. Therefore, it is possible to realize a compact projection lens having high optical performance and light resistance and a projector including the same. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance, downsizing, etc. will be described below.

It is more desirable to satisfy the following conditional expression (1a).
0.675 <0.0018 × Vd + P (1a)
The conditional expression (1a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (1). Therefore, preferably, the above-described effect can be further increased by satisfying conditional expression (1a).

It is more desirable to satisfy the following conditional expression (2a).
75 <Vd (2a)
This conditional expression (2a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (2). Therefore, preferably, the above-described effect can be further increased by satisfying conditional expression (2a).

It is desirable to satisfy the following conditional expressions (3) and (4).
1.2 <fp / f <2.5 (3)
2.5 <| f1 | / f (4)
However,
fp: the combined focal length of the lens group consisting of all the lenses located on the reduction side of the fourth lens,
f1: focal length of the first lens,
f: focal length of the entire system,
It is.

  By placing a positive lens with relatively strong power on the reduction side and a meniscus lens with low power on the enlargement side, the overall length is kept compact, ensuring telecentricity, and better field curvature and distortion. It becomes possible to correct. In other words, satisfying conditional expression (3) makes it easy to ensure compactness and telecentricity, and satisfying conditional expression (4) facilitates correction of field curvature and distortion.

  If the lower limit of conditional expression (3) is exceeded, it will be difficult to sufficiently correct field curvature and distortion. If the upper limit of conditional expression (3) is exceeded, telecentricity may deteriorate. If the lower limit of conditional expression (4) is exceeded, it will be difficult to sufficiently correct field curvature and distortion.

It is more desirable to satisfy the following conditional expression (3a).
1.4 <fp / f <2.3 (3a)
This conditional expression (3a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (3). Therefore, preferably, the above-described effect can be further increased by satisfying conditional expression (3a).

It is more desirable to satisfy the following conditional expression (4a).
4 <| f1 | / f (4a)
The conditional expression (4a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (4). Therefore, the above effect can be further increased preferably by satisfying conditional expression (4a).

It is desirable to satisfy the following conditional expression (5).
-2 <f3 / f4 <-0.5 (5)
However,
f3: focal length of the third lens,
f4: focal length of the fourth lens,
It is.

  By satisfying the conditional expression (5) by the negative third lens and the positive fourth lens, the axial chromatic aberration can be corrected well. If the upper limit or lower limit of conditional expression (5) is exceeded, it will be difficult to sufficiently correct axial chromatic aberration.

It is more desirable to satisfy the following conditional expression (5a).
−1.8 <f3 / f4 <−0.6 (5a)
This conditional expression (5a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (5). Therefore, the above effect can be further increased preferably by satisfying conditional expression (5a).

It is desirable to satisfy the following conditional expression (6).
T34 / f <0.05 (6)
However,
T34: air distance on the optical axis between the third lens and the fourth lens,
It is.

  When the distance between the aspheric surfaces is made closer, it is possible to obtain the same effect as when the third and fourth lenses are cemented lenses. Therefore, chromatic aberration can be favorably corrected by satisfying conditional expression (6). If the upper limit of conditional expression (6) is exceeded, chromatic aberration may be deteriorated.

It is more desirable to satisfy the following conditional expression (6a).
T34 / f <0.04 (6a)
The conditional expression (6a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (6). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (6a).

It is desirable to satisfy the following conditional expressions (7) and (8).
0.4 <Rf / Y ′ <0.8 (7)
1 <Rr / Y ′ <1.25 (8)
However,
Rf: effective radius of the most magnified lens surface,
Rr: effective radius of the lens surface closest to the reduction side,
Y ′: reduced-side image circle radius,
It is.

  By appropriately setting the lens diameter on the most enlargement side and the lens diameter on the most reduction side, it becomes possible to realize a compact and high-performance optical system, and by cutting the unused portion of the lens on the reduction side, Furthermore, it is possible to make it compact. When the conditional expression (7) is satisfied, the front lens becomes smaller with respect to the reduced-side image circle radius Y ′, so that compactness is possible. When conditional expression (8) is satisfied, telecentricity is ensured, but since it is assumed that only one side is used with respect to the optical axis, the front lens can be made smaller and the whole can be made compact. .

  If the lower limit of conditional expression (7) is exceeded, it will be difficult to sufficiently correct field curvature and distortion. If the upper limit of conditional expression (7) is exceeded, the diameter and lens length may increase. If the lower limit of conditional expression (8) is exceeded, it will be difficult to maintain telecentricity. If the upper limit of conditional expression (8) is exceeded, the diameter or lens length may increase.

It is more desirable to satisfy the following conditional expression (7a).
0.45 <Rf / Y ′ <0.75 (7a)
This conditional expression (7a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (7). Therefore, the above effect can be further increased preferably by satisfying conditional expression (7a).

It is more desirable to satisfy the following conditional expression (8a).
1 <Rr / Y ′ <1.2 (8a)
This conditional expression (8a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (8). Therefore, the above effect can be further increased preferably by satisfying conditional expression (8a).

  It is desirable to have an aperture stop between the second lens and the third lens. If the aperture stop is arranged in this way, coma can be appropriately reduced. In addition, since the enlargement side lens diameter can be set to an appropriate size, it is preferable for realizing a compact optical system. That is, it is possible to achieve a good balance between coma aberration correction and the enlargement side lens diameter size.

  It is desirable that the glass transition temperature of all lens materials is 250 ° C. or higher. This means that a plastic lens is not used, so that local temperature rise due to laser light can be prevented and alteration due to laser light can be prevented. Therefore, it is possible to realize a projection lens that has excellent light resistance and heat resistance and can be used without any problem even with a laser light source.

  Here, the specific optical configuration of the projection lens LN will be described in more detail with reference to the first and second embodiments. 1 and 2 are optical path diagrams respectively corresponding to the projection lenses LN constituting the first and second embodiments, and their lens arrangements, optical paths and the like are shown in optical cross sections. In the first and second embodiments, a prism PR (for example, a TIR (Total Internal Reflection) prism, a color separation / combination prism, etc.) and an image display element are provided on the reduction side of the projection lens LN that is substantially telecentric on the reduction side. The cover glass CG is located, and the image display surface IM corresponds to the reduced side image surface.

  The projection lens LN of the first embodiment (FIG. 1) is composed of six lenses L1 to L6 in order from the enlargement side, and the second to fourth lenses L2 to L4 are double-sided aspheric lenses. And an aperture stop ST is provided between the second and third lenses L2 and L3. The first lens L1 is a positive meniscus lens convex on the enlargement side, the second lens L2 is a negative meniscus lens convex on the enlargement side, the third lens L3 is a negative meniscus lens concave on the enlargement side, The lens L4 is a biconvex positive lens, the fifth lens L5 is a positive meniscus lens convex on the reduction side, and the sixth lens L6 is a biconvex positive lens.

  The projection lens LN of the second embodiment (FIG. 2) is composed of five lenses L1 to L5 in order from the enlargement side, and the second to fourth lenses L2 to L4 are double-sided aspheric lenses. There is an aperture stop ST between the second and third lenses L2, L3. The first lens L1 is a positive meniscus lens convex on the enlargement side, the second lens L2 is a negative meniscus lens convex on the enlargement side, the third lens L3 is a biconcave negative lens, and the fourth lens L4 is It is a biconvex positive lens, and the fifth lens L5 is a biconvex positive lens.

  Next, an embodiment of a projector to which the projection lens LN is applied will be described. FIG. 5 shows a schematic configuration example of the projector PJ. The projector PJ includes a light source 2, an illumination optical system 3, an image display element 4, a control unit 5, an actuator 6, a prism PR, a projection lens LN, and the like. The control unit 5 is a part that controls the entire projector PJ. The image display element 4 is an image modulation element (for example, a digital micromirror device) that modulates light to generate an image, and a cover glass CG is provided on the image display surface IM that displays an image. Yes.

  Light emitted from the light source 2 (for example, laser light emitted from the laser light source) is guided to the image display element 4 by the illumination optical system 3 and the prism PR. The prism PR includes, for example, a TIR prism, a color separation / synthesis prism, and the like, and performs separation of illumination light and projection light. The image displayed on the image display element 4 is enlarged and projected on the screen surface 1 by the projection lens LN. However, since it is assumed that only one side is used with respect to the optical axis AX, the entire system can be made compact by omitting the unused portion.

  An actuator 6 that moves to the enlargement side or the reduction side along the optical axis AX is connected to a lens group that moves for zooming or focusing in the projection lens LN. The actuator 6 is connected to a control unit 5 for performing movement control of the moving group. The control unit 5 and the actuator 6 may be moved manually without using them.

  Hereinafter, the configuration and the like of the projection lens embodying the present invention will be described more specifically with reference to the construction data of the examples. Examples 1 and 2 (EX1 and EX2) mentioned here are numerical examples corresponding to the first and second embodiments described above, and are optical path diagrams (first and second embodiments). FIGS. 1 and 2 show the lens configurations, optical paths, and the like of the corresponding first and second embodiments.

In the construction data of each embodiment, as surface data, in order from the left column, the surface number i, the radius of curvature r (mm), the axial distance d (mm), the refractive index Nd with respect to the d-line (wavelength 587.6 nm), The Abbe number Vd with respect to the d line is shown. A surface with * in the surface number is an aspheric surface, and the surface shape is defined by the following expression (AS) using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin. . As aspheric data, an aspheric coefficient or the like is shown. It should be noted that the coefficient of the term not described in the aspherical data of each example is 0, and E−n = × 10 ⁻ⁿ for all data.
z = (c · h ² ) / {1 + √ (1−ε · c ² · h ² )} + Σ (Aj · h ^j ) (AS)
However,
h: height in the direction perpendicular to the z axis (optical axis AX) (h ² = x ² + y ² ),
z: the amount of sag in the direction of the optical axis AX at the position of the height h (based on the surface vertex),
c: curvature at the surface vertex (the reciprocal of the radius of curvature r),
ε: quadric surface parameter,
Aj: j-order aspheric coefficient,
It is.

  As various data, the focal length (f, mm) of the entire system, F number (FNo), back focus (BF, air conversion value, mm), lens total length (TL, mm), half angle of view (ω, °), The image height (Y ′: reduced-side image circle radius, mm) is shown. Further, the focal length (fk, mm) of the kth lens Lk (k = 1, 2, 3,...), The combined focal length (f456, f45, mm) after the fourth lens L4, and the combined after the fifth lens L5. Focal length (f56, mm), focal length ratio with respect to the focal length f of the entire system, focal length ratio between the third lens L3 and the fourth lens L4, and third and fourth lens intervals with respect to the focal length f of the entire system A ratio of T34, a ratio of the back focus BF to the focal length f of the entire system, a ratio of the back focus BF to the total lens length TL, and the like are shown. In the back focus BF, the distance from the lens final surface to the paraxial image surface IM is expressed in terms of air length, and the total lens length TL is obtained by adding the back focus BF to the distance from the lens front surface to the lens final surface. It is a thing.

  Tables 1 and 2 show related data of each conditional expression for each example, and Table 3 shows corresponding values of the conditional expressions (3) to (8) of each example. In Table 1 and Table 2, the partial dispersion ratio P = (Ng−NF) / (NF−NC), which is related data of the conditional expression (1), and the corresponding value of the conditional expression (1): 0.0018 × Vd + P , Glass transition temperature Tg (° C.), effective radius R (mm), and related data of conditional expressions (7) and (8): R / Y ′.

  3 and 4 are aberration diagrams corresponding to Examples 1 and 2 (EX1 and EX2), respectively, and show various aberrations at a projection distance of 597 mm. 3 and 4, (A) shows spherical aberration (mm), (B) shows astigmatism (mm), (C) shows distortion (%), and (D) shows chromatic aberration of magnification (mm). (H: incident height (mm), Y ′: image height (mm)). In the spherical aberration diagram of (A), solid line SA-e indicates spherical aberration with respect to e-line (wavelength 546.1 nm), broken line SA-g indicates spherical aberration with respect to g-line (wavelength 435.8 nm), and alternate long and short dash line SA-C indicates C. The spherical aberration with respect to the line (wavelength 656.3 nm) is shown respectively. In the astigmatism diagram of (B), mer-e, mer-g, and mer-C indicated by thick lines are meridional image planes, and sag-e, sag-g, and sag-C indicated by thin lines are sagittal image planes, Solid lines mer-e and sag-e represent e-line, broken lines mer-g and sag-g represent g-line, and alternate long and short dash lines mer-C and sag-C represent astigmatism with respect to C-line. In the distortion diagram of (C), the solid line represents the distortion (%) with respect to the e-line, and in the magnification chromatic aberration diagram of (D), the broken line represents the g-line, and the alternate long and short dash line represents the magnification chromatic aberration with respect to the C-line.

  When each embodiment is used as a projection lens LN in a projector (for example, a liquid crystal projector) PJ, the screen surface (projected surface) 1 is originally an image surface and the image display surface IM (for example, a liquid crystal panel surface) is an object surface. However, in each embodiment, a reduction system is used for optical design, and the screen surface 1 (FIG. 5) is regarded as an object surface, and the optical performance is evaluated on the image display surface IM. As can be seen from the obtained optical performance, the projection lens of each embodiment can be suitably used not only as a projection lens for a projector but also as an imaging lens for an imaging device (for example, a video camera or a digital camera). is there.

Example 1
Unit: mm
Surface data
ird Nd Vd
1 4.772
1.27 2.00272 19.32
2 4.842
0.20
3 * 3.267
0.30 1.58313 59.46
4 * 2.295
1.90
5 (ST) ∞
1.26
6 * -2.747
0.32 1.70730 31.59
7 * -16.362
0.20
8 * 18.788
3.09 1.49710 81.56
9 * -3.123
0.20
10 -16.619
2.22 1.49700 81.61
11 -8.175
0.20
12 39.765
3.80 1.49700 81.61
13 -11.027
1.75
14 ∞
9.20 1.90366 31.31
15 ∞
0.00
16 ∞
1.60 1.51680 64.20
17 ∞
0.50
18 (IM) ∞

Aspheric data
i ε A4 A6 A8
3 1.000E + 00 1.459E-02 -1.813E-03 2.332E-05
4 1.000E + 00 1.458E-02 -1.998E-03 -6.724E-04
6 1.000E + 00 -1.262E-02 -1.845E-03 -9.587E-05
7 1.000E + 00 -9.449E-03 -3.448E-04 4.730E-05
8 1.000E + 00 -4.080E-03 2.464E-04 -6.558E-06
9 -5.199E-02 -2.273E-03 -1.378E-04 1.412E-05

Various data
f 6.951 (mm)
FNo 4.5
BF (air) 8.14 (mm)
TL 23.08 (mm)
ω 35.6 (deg)
Y '4.85 (mm)
f1 32.070 (mm)
f2 -14.858 (mm)
f3 -4.677 (mm)
f4 5.635 (mm)
f5 29.683 (mm)
f6 17.761 (mm)
f56 11.330 (mm)
f456 4.841 (mm)
f1 / f 4.613
f2 / f -2.137
f3 / f -0.673
f4 / f 0.811
f5 / f 4.270
f6 / f 2.555
f56 / f 1.630
f456 / f 0.696
f3 / f4 -0.830
f4 / f3 -1.205
T34 / f 0.029
BF / f 1.171
BF / TL 0.353

Example 2
Unit: mm
Surface data
ird Nd Vd
1 4.865
1.18 2.00272 19.32
2 4.500
0.20
3 * 4.932
1.00 1.58313 59.46
4 * 2.709
1.72
5 (ST) ∞
1.10
6 * -177.551
3.42 1.84666 23.78
7 * 9.197
0.20
8 * 16.435
3.22 1.58313 59.46
9 * -4.388
0.20
10 12.190
4.27 1.49700 81.61
11 -17.430
0.95
12 ∞
9.20 1.90366 31.31
13 ∞
0.00
14 ∞
1.60 1.51680 64.20
15 ∞
0.50
16 (IM) ∞

Aspheric data
ε A4 A6 A8
3 1.000E + 00 9.956E-03 -6.251E-04 9.389E-05
4 1.000E + 00 1.791E-02 -1.041E-03 6.830E-04
6 1.000E + 00 -1.720E-03 7.228E-04 -8.096E-05
7 1.000E + 00 -3.416E-03 1.623E-04 -4.004E-06
8 1.000E + 00 -1.388E-03 4.264E-05 -1.469E-06
9 -2.587E + 00 -4.055E-03 1.510E-04 -3.184E-06

Various data
f 6.953 (mm)
FNo 4.4
BF (air) 7.34 (mm)
TL 23.84 (mm)
ω 35.0 (deg)
Y '4.85 (mm)
f1 94.313 (mm)
f2 -12.310 (mm)
f3 -10.141 (mm)
f4 6.274 (mm)
f5 15.116 (mm)
f45 4.862 (mm)
f1 / f 13.564
f2 / f -1.770
f3 / f -1.458
f4 / f 0.902
f5 / f 2.174
f45 / f 0.699
f3 / f4 -1.616
f4 / f3 -0.619
T34 / f 0.029
BF / f 1.055
BF / TL 0.308

LN projection lens Lk kth lens (k = 1, 2, 3,...)
ST stop (aperture stop)
IM image display surface (reduction side image surface)
PJ Projector PR Prism 1 Screen surface 2 Light source 3 Illumination optical system 4 Image display element 5 Control unit 6 Actuator AX Optical axis

Claims (8)

A projection lens that is nearly telecentric on the reduction side,
In order from the magnifying side, a first lens having a convex meniscus shape on the magnifying side, a second lens having a negative meniscus shape on the magnifying side, a third lens having a negative power, and a positive lens convex on the reducing side A fourth lens of power and a fifth lens of positive power convex on the reduction side,
The facing surfaces of the third lens and the fourth lens are different aspherical surfaces,
A projection lens in which at least one of the positive lenses existing on the reduction side of the fourth lens satisfies the following conditional expressions (1) and (2);
0.66 <0.0018 × Vd + P (1)
60 <Vd (2)
However,
Vd: Abbe number for the d line,
P = (Ng-NF) / (NF-NC)
Ng: refractive index for g-line,
NF: refractive index for F-line,
NC: Refractive index for C-line,
It is. The projection lens according to claim 1, wherein the following conditional expressions (3) and (4) are satisfied:
1.2 <fp / f <2.5 (3)
2.5 <| f1 | / f (4)
However,
fp: the combined focal length of the lens group consisting of all the lenses located on the reduction side of the fourth lens,
f1: focal length of the first lens,
f: focal length of the entire system,
It is. The projection lens according to claim 1, wherein the following conditional expression (5) is satisfied:
-2 <f3 / f4 <-0.5 (5)
However,
f3: focal length of the third lens,
f4: focal length of the fourth lens,
It is. The projection lens according to claim 1, wherein the following conditional expression (6) is satisfied:
T34 / f <0.05 (6)
However,
T34: air distance on the optical axis between the third lens and the fourth lens,
It is. The projection lens according to claim 1, wherein the following conditional expressions (7) and (8) are satisfied:
0.4 <Rf / Y ′ <0.8 (7)
1 <Rr / Y ′ <1.25 (8)
However,
Rf: effective radius of the most magnified lens surface,
Rr: effective radius of the lens surface closest to the reduction side,
Y ′: reduced-side image circle radius,
It is.   The projection lens according to claim 1, further comprising an aperture stop between the second lens and the third lens.   The projection lens according to claim 1, wherein all lens materials have a glass transition temperature of 250 ° C. or higher.   8. An image display element that displays an image, a light source, an illumination optical system that guides light from the light source to the image display element, and an image displayed on the image display element is enlarged and projected onto a screen surface. A projector comprising the projection lens according to any one of the above.

Images