JP2002341242A - Projection lens and projector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection lens by which a picture having a high quality is realized over an entire screen by sufficiently correcting transverse chromatic aberration, which is made small-sized and is made light in weight and whose cost is low in the projection lens to enlarge and project an optical image illuminated with light from a light source on a spatial optical modulating element on a screen. SOLUTION: This projection lens is provided with a first group lens G1 constituted of at least two lenses, a diaphragm SP and a second group lens G2 having positive refracting power in order from a screen side, and when the focal distance of an i-th lens is set as fi and the Abbe number of a lens thereof is set as vi, all lenses constituting the second group lens satisfy the condition of -0.0004<Σ(1/(fi×vi))<0.0015. Thus, the transverse chromatic aberration is excellently corrected, so that an excellent picture is displayed in the entire range of the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens, and more particularly to a projection lens for a projector for enlarging and projecting an image formed on a spatial light modulator on a screen. Also,
The present invention relates to a video magnifying projection system including such a projection lens, a video projector, a rear projector, and a multi-vision system.

[0002]

2. Description of the Related Art As a method for obtaining a large-screen image, an optical image corresponding to an image signal is formed on a spatial light modulator, the optical image is irradiated with light, and the optical image is projected on a screen through a projection lens. A method of enlarging and projecting the image is well known. Recently, a projector using a liquid crystal panel as a spatial light modulator has been receiving attention.

As a method of obtaining a color image, light from a light source is temporally divided into red (R), green (G), and blue (B) color lights while illuminating one liquid crystal panel. A method of driving a liquid crystal panel with a video signal corresponding to the color of the illumination light;
While illuminating the three liquid crystal panels with the R, G, and B color lights, respectively, the three liquid crystal panels are driven with the video signals of the R, G, and B colors, respectively, and three dichroic prisms are used. A method of synthesizing an image on a liquid crystal panel is known.

[0004]

In a projector using a prism, a large space is required between the projection lens and the spatial light modulator, so that the projection lens needs to have a long back focus.

In a projector using a prism,
The dependence of the incident angle of the incident light on the prism is large, and the light incident on the prism at an angle other than the designed incident angle changes in transmittance, resulting in uneven color and brightness on the screen. Therefore, the projection lens needs to be telecentric.

In a projector for data display or graphic display which requires strict performance around the screen, it is important that there is no graphic distortion or color bleeding, and distortion and chromatic aberration of magnification of the projection lens are well corrected. It is necessary to be.

Usually, the projection lens is required to have a large angle of view because the projection lens is used with its optical axis shifted upward with respect to the spatial light modulator. Further, in order to reduce the distance between the projector and the screen and enable enlarged projection even in a small space, it is desired to have a still larger angle of view.

[0008] The set body of the projector has been reduced in size and price, and the projection lens has been reduced in size and weight.
Low cost is being demanded.

The present invention has been made in view of the above-mentioned conventional problems. By appropriately setting the lens configuration, chromatic aberration at a magnification which is particularly strictly required as a projection lens can be sufficiently corrected, and the entire screen can be corrected. Accordingly, an object of the present invention is to provide a small and lightweight projection lens capable of realizing a high-quality image at a low price.

[0010]

In order to achieve the above object, the present invention has the following arrangement.

A first projection lens according to the present invention is a projection lens for enlarging and projecting an optical image illuminated by light from a light source onto a screen, and comprises at least two lenses in order from the screen side. It comprises a first group lens, a stop, and a second group lens having a positive refractive power, and satisfies the following condition.

(1) −0.0004 <Σ (1 / (fi × vi)) <0.0015 where Σ (1 / (fi × vi)): The focal length of the i-th lens from the screen side is fi Of the 1 / (fi × vi) obtained for each lens when the Abbe number of the lens is vi, 1 / (fi × vi) for all lenses constituting the second group lens
Is the sum of

A second projection lens according to the present invention is characterized in that in the above-mentioned first configuration, the following condition is satisfied, preferably together with conditional expression (1) instead of conditional expression (1).

(2) 0.9 <fG2 / bf <1.3, where fG2: focal length of the second group lens bf: air conversion length of the back focus of the projection lens.

A third projection lens according to the present invention is characterized in that in the above-mentioned first configuration, the following condition is satisfied, preferably together with conditional expression (1) instead of conditional expression (1).

(3) −2.0 <rG2 / tG2p <−0.65 where, rG2 is a radius of curvature of a screen-side surface of a negative lens having a concave surface facing the screen, which constitutes the second lens unit, tG2p: From the screen side focal position of the second group lens,
The distance measured on the optical axis to the vertex of the screen side surface of the negative lens having the concave surface facing the screen side, which constitutes the second group lens.

A fourth projection lens according to the present invention is characterized in that in the above-mentioned first configuration, the following condition is satisfied, preferably together with conditional expression (1) instead of conditional expression (1).

(4) 0.95 <fG1 / fG2 <1.2, where fG1: focal length of the first group lens fG2: focal length of the second group lens

According to the first to fourth projection lenses, since the lens configuration is properly set, the projection distance can be short, the back focus can be long, and an image with less color blur and distortion can be realized. A lens can be provided.

It is preferable that the first to fourth projection lenses are of an exit side telecentric system. As a result, the angle of incidence of the incident light on the prism located between the projection lens and the spatial light modulator that forms the optical image becomes uniform regardless of the screen position, so that the color unevenness of the enlarged and projected image is reduced. Can be suppressed.

The first to fourth projection lenses are provided with
Preferably, the number is 2.6 or less and the angle of view is 48 degrees or more.

Next, the image enlargement projection system of the present invention
A light source, a spatial light modulator that forms an optical image while being illuminated with light emitted from the light source, and a projection unit that enlarges and projects the optical image on the spatial light modulator,
The projection means is any one of the first to fourth projection lenses. As a result, a compact image enlarged projection system can be obtained.

Also, the video projector of the present invention
A light source, means for decomposing light from the light source into three color lights of blue, green and red, and an optical image illuminated by the three color lights of blue, green and red and corresponding to the illuminated color lights A spatial light modulator, and projection means for enlarging and projecting the optical image on the spatial light modulator, wherein the projection means is any one of the first to fourth projection lenses. As a result, the chromatic aberration of magnification is well corrected, and when three spatial light modulators are used, images of three colors of blue, green, and red can be projected on the screen without shifting, and the image can be brightened. As a result, a high-definition video can be obtained, and a video projector that can be used in a small space because of a short projection distance can be realized.

The rear projector according to the present invention is also a video projector according to the present invention, a mirror that bends light projected from the video projector, and a transmissive screen that projects an image when light reflected by the mirror enters. And characterized in that: This allows
Since the projection distance of the projection lens is short, a compact set can be realized.

A multi-vision system according to the present invention includes a plurality of units each including the video projector according to the present invention and a transmissive screen that projects an image by receiving light projected from the video projector, and further divides the image. A video dividing circuit is provided. Accordingly, a set with a short depth can be realized because the projection distance of the projection lens is short.

[0026]

(Embodiment 1) In this embodiment, telecentricity and small chromatic aberration of magnification are realized with an appropriate lens arrangement.

In order to obtain telecentricity, it is necessary to bend the principal ray from a half angle of view, which comes from the specification of the lens, to horizontal. This means that the principal ray is greatly bent as compared with a lens having no telecentricity. This imposes a very large burden on correcting distortion and chromatic aberration of magnification.

It is known that it is advantageous to take a symmetrical configuration with respect to the stop in order to satisfactorily correct distortion and chromatic aberration of magnification. However, as long as it is telecentric, the symmetry of the chief ray is maintained. You can't get it. In order to obtain a longer back focus, a retrofocus type configuration is required. The rear group of the retrofocus type has a high on-axis ray height and greatly affects on-axis chromatic aberration. Further, in order to provide telecentricity, the principal ray height of the rear group needs to be the same as the maximum image height. Therefore, the rear group greatly affects the chromatic aberration of magnification. That is, the rear group of the retro-focus type lens having telecentricity greatly affects both the axial chromatic aberration and the chromatic aberration of magnification.

The projection lens according to the first embodiment is a projection lens composed of a first lens unit, a stop, and a second lens unit in this order from the screen side. The focal length of the i-th lens from the screen side is fi. When the Abbe number of the lens is defined as vi, the reciprocal (1 / (fi × vi)) of the product of the product of the focal length fi and the Abbe number vi for each lens, all of which constitute the second group lens 1 / (fi × vi) about lens
The chromatic aberration of magnification is corrected by reducing the total value (Σ (1 / (fi × vi))) obtained by adding.

A projection lens according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a projection lens according to the first embodiment.

The projection lens of the first embodiment has a first group lens G1 and a second group lens G2 having a positive refractive power before and after the aperture stop SP.

S is a screen. The projection lens enlarges and projects the image displayed on the spatial light modulator B such as a liquid crystal panel on the screen S.

GB is a color combining prism or a total reflection prism for introducing illumination light.

The projection lens according to the first embodiment includes, in order from the screen S side, an eleventh positive lens L11, a negative twelfth meniscus lens L12 having a convex surface facing the screen side,
A first group lens G1 having a meniscus negative thirteenth lens L13 having a convex surface facing the screen side and having a negative refractive power as a whole, a diaphragm SP, and a positive twenty-first lens L
21, a cemented lens obtained by cementing a positive twenty-second lens L22 and a negative twenty-third lens L23, a positive twenty-fourth lens L24, and a meniscus negative twenty-fifth lens L having a concave surface facing the screen side
25, and a second lens group G2 having a positive 26th lens L26 and a positive refractive power as a whole.

The eleventh lens L11 has a positive refractive power and generates higher-order distortion to correct the distortion of the entire system. Since this function has an effect of excessively correcting lateral chromatic aberration at a large angle of view, the Abbe number of the eleventh lens L11 is preferably 40 or more.

The twelfth lens L12 and the thirteenth lens L13
It is preferable that each of them has a negative refractive power in order to secure the back focus of the entire system, and has a meniscus shape with a convex surface facing the screen side in order to suppress the occurrence of distortion.

The twenty-first lens L21 is a meniscus lens having a positive refractive power with a convex surface facing the screen side to correct coma.

The twenty-second lens L22 and the twenty-third lens L23 are cemented, and the joint surface faces the concave surface toward the screen.
This joint surface corrects chromatic aberration of magnification, and the concave surface of the joint surface on the screen side prevents overcorrection of chromatic aberration of magnification at a large angle of view.

The twenty-fifth lens L25 has a negative refractive index in a meniscus shape having a concave surface facing the screen, and corrects chromatic aberration of magnification so that chromatic aberration of magnification is not excessively corrected at a large angle of view. Therefore, the Abbe number of the 25th lens L25 is 3
It is preferably three or more.

The projection lens according to the first embodiment is
It satisfies the relationship of the conditional expression (1).

Thus, the chromatic aberration of magnification is favorably corrected,
Good images can be provided over the entire screen range.

Equation (1) is an equation relating to the focal length and Abbe number of each lens constituting the second group lens G2. Σ (1
If (/ (fi × vi)) is below the lower limit, lateral chromatic aberration will be overcorrected. In this state, if the first group lens attempts to correct lateral chromatic aberration, axial chromatic aberration will be overcorrected. When the value exceeds the upper limit, lateral chromatic aberration is insufficiently corrected.

Embodiment 1 will be described below as a specific numerical example of the present invention.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
1 is a configuration diagram of a projection lens according to Example 1 of FIG.

In the first embodiment, F _NO = 2.1 and the focal length f
= 20.3, angle of view 2w = 59.4 °, is a design example aiming at long back focus, telecentricity, and correction of chromatic aberration and distortion of magnification. .

FIG. 2 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the first embodiment. In the spherical aberration diagram of FIG. 2, the solid line is e-line, and the broken line is f-line. In the astigmatism diagram of FIG. 2, S is sagittal field curvature, and T is meridional field curvature. In the magnification chromatic aberration diagram of FIG. 2, the solid line is the value of the magnification chromatic aberration of the F line with respect to the e line.

Next, specific numerical values are shown in Table 1. Ri in the table
Is the radius of curvature of each lens surface, and di is the lens thickness or the distance between lenses. ni is the refractive index of each lens at d-line. νi is the Abbe number of each lens at the d-line. In addition,
i is counted in order from the screen S side.

The aspherical shape is a rotationally symmetric aspherical surface expressed by the following equation, where X is a displacement amount from the lens vertex at a position of a radial distance h of the aperture from the optical axis of the lens.

[0049]

(Equation 1)

[0050]

Conditional expression (1): Σ (1 / (fi × vi)) = 0.000902 Conditional expression (2): fG2 / bf = 0.823 Conditional expression (3): rG2 / tG2p = −3.138 Conditional expression (4) : FG1 / fG2 = 1.897 f = 20.30 fNo = 2.1 2w = 59.4 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 42.972 d 1 = 4.0 n 1 = 1.80420 v 1 = 46.50 r 2 = 151.417 d 2 = 0.3 r 3 = 25.506 d 3 = 0.9 n 2 = 1.49700 v 2 = 81.61 r 4 = 12.226 d 4 = 6.7 r 5 = 62.429 d 5 = 1.1 n 3 = 1.49700 v 3 = 81.61 r 6 = 13.880 d 6 = 9.4 r 7 = 18.942 d 7 = 2.7 n 4 = 1.78472 v 4 = 25.72 r 8 = 23.911 d 8 = 12.8 r 9 = -39.469 d 9 = 7.9 n 5 = 1.77250 v 5 = 49.62 r10 = -12.656 d10 = 1.2 n 6 = 1.80518 v 6 = 25.46 r11 = -24.917 d11 = 1.0 r12 = -1550.808 d12 = 5.4 n 7 = 1.58913 v 7 = 61.25 r13 = -33.868 d13 = 2.9 r14 = -21.039 d14 = 1.5 n 8 = 1.74950 v 8 = 35.04 r15 = -28.133 d15 = 1.0 r16 = 63.304 d16 = 7.3 n 9 = 1.58913 v 9 = 61.25 r17 = -58.011 d17 = 7.7 r18 = 0.000 d18 = 25.0 n10 = 1.51680 v10 = 64.20 r19 = 0.000 d19 = 6.8

(Embodiment 2) A projection lens according to Embodiment 2 of the present invention will be described with reference to the drawings.
FIG. 3 is a configuration diagram of a projection lens according to the second embodiment.

The projection lens according to the second embodiment includes, in order from the screen S side, an eleventh positive lens L11, a negative twelfth meniscus lens L12 having a convex surface facing the screen side,
Meniscus negative thirteenth with the convex surface facing the screen side
A first lens group G1 having a lens L13 and a positive fourteenth lens L14, and having a negative refractive power as a whole;
A cemented lens obtained by cementing a negative twenty-first lens L21, a positive twenty-second lens L22 and a negative twenty-third lens L23, a positive second lens
It has a fourth lens L24 and a positive twenty-fifth lens L25, and has a second group lens G2 having a positive refractive power as a whole.

The fourteenth lens L14 corrects chromatic aberration of magnification and distortion. In order to further correct lateral chromatic aberration, the Abbe number is preferably 30 or less.

The twenty-first lens L21 corrects distortion and astigmatism.

The projection lens according to the second embodiment is
It satisfies the relationship of the conditional expression (1).

Thus, the chromatic aberration of magnification is favorably corrected,
Good images can be provided over the entire screen range.

Equation (1) is an equation relating to the focal length and Abbe number of each lens constituting the second group lens G2. Σ (1
If (/ (fi × vi)) is below the lower limit, lateral chromatic aberration will be overcorrected. In this state, if the first group lens attempts to correct lateral chromatic aberration, axial chromatic aberration will be overcorrected. When the value exceeds the upper limit, lateral chromatic aberration is insufficiently corrected.

Hereinafter, Embodiment 2 will be described as a specific numerical example of the present invention.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
FIG. 9 is a configuration diagram of a projection lens according to Example 2 of FIG.

In the second embodiment, F _NO = 2.1 and the focal length f
= 20.07 and an angle of view 2w = 60.0 °, which is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 4 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the second embodiment.

Next, specific numerical values are shown in Table 2.

[0063]

Conditional expression (1): Σ (1 / (fi × vi)) = 0.000921 Conditional expression (2): fG2 / bf = 0.805 Conditional expression (3): rG2 / tG2p = −3.757 Conditional expression (4) : FG1 / fG2 = 4.138 f = 20.07 fNo = 2.1 2w = 60.0 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 45.023 d 1 = 4.0 n 1 = 1.80420 v 1 = 46.50 r 2 = 160.641 d 2 = 0.3 r 3 = 30.274 d 3 = 0.9 n 2 = 1.49700 v 2 = 81.61 r 4 = 14.183 d 4 = 6.7 r 5 = 47.523 d 5 = 1.1 n 3 = 1.49700 v 3 = 81.61 r 6 = 14.792 d 6 = 9.4 r 7 = 33.142 d 7 = 2.7 n 4 = 1.78472 v 4 = 25.72 r 8 = 77.830 d 8 = 9.0 r 9 = -223.699 d 9 = 2.0 n 5 = 1.62004 v 5 = 36.37 r10 = 49.454 d10 = 5.5 r11 = -50.437 d11 = 7.9 n 6 = 1.77250 v 6 = 49.62 r12 = -12.951 d12 = 1.2 n 7 = 1.80518 v 7 = 25.46 r13 = -27.066 d13 = 1.0 r14 = 797.980 d14 = 5.4 n 8 = 1.58913 v 8 = 61.25 r15 = -41.852 d15 = 2.0 r16 = 52.614 d16 = 7.3 n 9 = 1.58913 v 9 = 61.25 r17 = -98.324 d17 = 7.5 r18 = 0.000 d18 = 25.0 n10 = 1.51680 v10 = 64.20 r19 = 0.000 d19 = 6.9

(Embodiment 3) A projection lens according to Embodiment 3 of the present invention will be described with reference to the drawings.
FIG. 5 is a configuration diagram of a projection lens according to the third embodiment.

In the third embodiment, by properly arranging the lenses, a projection lens which can favorably correct axial chromatic aberration, lateral chromatic aberration, and distortion while having a long back focus with telecentricity is realized. are doing.

In order to provide telecentricity and to realize a back focus longer than the focal length of the entire system, in the second group lens G2 on the side of the spatial light modulator B from the stop SP, the height of the on-axis light beam is reduced. And the principal ray height is also the same as the maximum image height. Therefore, the second group lens has a large effect on spherical aberration and axial chromatic aberration, and a large effect on distortion and chromatic aberration of magnification. In particular, the refractive power of the second lens group greatly affects the size of the entire system and the correction of aberrations.

Since the telecentricity must be maintained, the refractive power of the second lens unit is proportional to the total deflection angle of the principal ray in the second lens unit.

In order to satisfactorily correct distortion and chromatic aberration of magnification, it is only necessary to reduce the total deflection angle of the principal ray.
This can be achieved by reducing the refractive power of the second group lens.

However, when the refracting power of the second lens unit is reduced, it is necessary to increase the axial ray height of the first lens unit in order to secure the back focus. The length of the projection lens must be increased, and the size of the entire projection lens increases.

In the third embodiment, the ratio f of the focal length fG2 of the second group lens to the back focus bf of the whole system
G2 / bf is set appropriately. In this way, the deflection angle of the principal ray in the second group lens can be suppressed small, and the axial ray from the first group lens to the second group lens is converged toward the second group lens. It can be. On each surface of the second group lens having negative refractive power, the incident angle of the axial ray of the convergent light increases, and the effect of correcting axial chromatic aberration and spherical aberration increases.

Generally, in a lens system having a positive refractive power, a lens having a negative refractive power is introduced to correct each aberration. When a lens having a negative refractive power is introduced, it is necessary to increase the refractive power of the positive lens in order to maintain the positive refractive power of the entire lens system. However, increasing the refractive power of the positive lens increases the generated aberration.

The fact that the effect of correcting axial chromatic aberration and spherical aberration can be increased as in the present embodiment means that the negative refractive power for correcting aberration can be reduced, and the negative refractive power can be reduced. If the power can be reduced, the positive refractive power can also be reduced, and the aberration correction can be improved.

Further, since the effect of correcting axial chromatic aberration can be enhanced by the second group lens, axial chromatic aberration can be insufficiently corrected by the first group lens. Since the axial chromatic aberration in the first lens unit is insufficiently corrected, the chromatic aberration of magnification in the first lens unit is also insufficiently corrected. Since the telecentricity must be ensured, the amount of declination of the principal ray in the second lens unit is larger than the amount of declination of the principal ray in the first lens unit. Is insufficiently corrected.
The chromatic aberration of magnification is insufficiently corrected by the first lens unit, the correction is also insufficient by the second lens unit, and the first lens unit and the second lens unit are located across the stop SP. They act so as to cancel each other out of chromatic aberration of magnification.

In the third embodiment, the ratio f of the focal length fG2 of the second group lens to the back focus bf of the whole system
By setting G2 / bf to an appropriate value, it is possible to reduce the negative refractive power required for correcting the chromatic aberration of magnification, and to provide the first lens unit with the chromatic aberration of magnification canceling the chromatic aberration of magnification generated by the second lens unit. Can be generated, and axial chromatic aberration, chromatic aberration of magnification, and distortion are satisfactorily corrected while having a long back focus having telecentricity.

The projection lens according to the third embodiment includes, in order from the screen S side, a meniscus negative eleventh lens L11 having a convex surface facing the screen side, a positive twelfth lens L12,
A first group lens G1 having a negative thirteenth lens L13 and a positive fourteenth lens L14 and having a positive refractive power as a whole
, Aperture SP, a negative twenty-first lens L21, a cemented lens obtained by cementing a positive twenty-second lens L22 and a negative twenty-third lens L23, a positive twenty-fourth lens L24, and a positive twenty-fifth lens L25
And the second group lens G having a positive refractive power as a whole
And 2.

The first group lens G1 has a high axial ray height in order to secure a back focus. Therefore, the negative eleventh lens L11, the positive twelfth lens L12, the negative first
The third lens L13 and the positive fourteenth lens L14 are arranged at intervals.

The projection lens according to the third embodiment is
It satisfies the relationship of the conditional expression (2) described above.

As a result, the longitudinal chromatic aberration and the chromatic aberration of magnification can be satisfactorily corrected, and a good image can be provided in the entire screen range.

Equation (2) is the ratio fG2 / f of the focal length fG2 of the second group lens G2 to the back focus bf of the entire system.
This is an expression related to bf. If the ratio fG2 / bf is below the lower limit, the refractive power of the second lens unit becomes so large that chromatic aberration of magnification cannot be corrected. Further, since the focal length of the second group lens is shorter than the back focus of the entire system, the on-axis rays entering the second group lens from the stop SP diverge toward the second group lens. The incident angle of the axial ray on the surface of the second lens unit having a negative refractive power becomes small, and the axial chromatic aberration and spherical aberration are insufficiently corrected. Beyond the upper limit, the entire projection lens becomes large. Further, since the on-axis ray height must be increased in the first group lens, a large negative refractive power is required, and the upper ray at a large angle of view is overcorrected by the first group lens. Correction cannot be made by the two-group lens, and as a result, the upper ray cannot be corrected at a large angle of view as a whole of the projection lens, resulting in a decrease in resolution and flare, thereby deteriorating the optical performance.

Hereinafter, Embodiment 3 will be described as a specific numerical example of the present invention.

(Embodiment 3) FIG. 5 shows Embodiment 3 of the present invention.
FIG. 9 is a configuration diagram of a projection lens according to Example 3 of the first embodiment.

In the third embodiment, F _NO = 2.1 and the focal length f
= 21.63, angle of view 2w = 57.2 °, and is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 6 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the third embodiment.

Next, specific numerical values are shown in Table 3.

[0085]

Table 3 Conditional expression (1): Σ (1 / (fi × vi)) = 0.000692 Conditional expression (2): fG2 / bf = 0.959 Conditional expression (3): rG2 / tG2p = 36.085 Conditional expression (4): fG1 / fG2 = 3.705 f = 21.63 fNo = 2.1 2w = 57.2 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 52.668 d 1 = 1.9 n 1 = 1.69680 v 1 = 55.46 r 2 = 26.167 d 2 = 8.0 r 3 = 118.113 d 3 = 5.0 n 2 = 1.72825 v 2 = 28.32 r 4 = -81.938 d 4 = 8.0 r 5 = -110.470 d 5 = 1.9 n 3 = 1.49700 v 3 = 81.61 r 6 = 15.598 d 6 = 7.0 r 7 = 30.292 d 7 = 4.0 n 4 = 1.77250 v 4 = 49.62 r 8 = -96.459 d 8 = 6.8 r 9 = -515.466 d 9 = 1.5 n 5 = 1.80518 v 5 = 25.46 r10 = 37.753 d10 = 3.0 r11 = 565.958 d11 = 6.0 n 6 = 1.61800 v 6 = 63.39 r12 = -42.496 d12 = 1.5 n 7 = 1.84666 v 7 = 23.78 r13 = 136.814 d13 = 1.3 r14 = -823.539 d14 = 6.0 n 8 = 1.77250 v 8 = 49.62 r15 = -24.715 d15 = 1.0 r16 = 41.955 d16 = 6.0 n 9 = 1.77250 v 9 = 49.62 r17 = -288.367 d17 = 7.0 r18 = 0.000 d18 = 26.7 n10 = 1.51680 v10 = 64.20 r19 = 0.000 d19 = 6.4

(Embodiment 4) A projection lens according to Embodiment 4 of the present invention will be described with reference to the drawings.
FIG. 7 is a configuration diagram of a projection lens according to the fourth embodiment.

The projection lens of the fourth embodiment includes, in order from the screen S side, a meniscus negative eleventh lens L11 with a convex surface facing the screen side, a positive twelfth lens L12,
A first lens group G1 having a positive refractive power as a whole, a stop SP, and a negative second lens L13.
A first lens L21, a cemented lens obtained by cementing a negative twenty-second lens L22 and a positive twenty-third lens L23, and a second lens group G2 having a positive twenty-fourth lens L24 and having a positive refractive power as a whole. Have.

When the refractive index of the twenty-fourth lens L24 is n24, it is preferable to satisfy the following condition: (5) 1.8 <n24

The above equation (5) gives the refractive index n24 of the twenty-fourth lens.
Is appropriately defined.

When the refractive index n24 of the twenty-fourth lens satisfies the expression (5), astigmatism can be favorably corrected. Refractive index n2
If 4 exceeds the lower limit of the expression (5), astigmatism will be insufficiently corrected, which is not appropriate.

Then, the projection lens of the fourth embodiment is
It satisfies the relationship of the conditional expression (2) described above.

As a result, the longitudinal chromatic aberration and the chromatic aberration of magnification can be satisfactorily corrected, and a good image can be provided in the entire screen range.

Embodiment 4 will be described below as a specific numerical example of the present invention.

(Embodiment 4) FIG. 7 shows Embodiment 4 of the present invention.
FIG. 9 is a configuration diagram of a projection lens according to Example 4 of the first embodiment.

In the fourth embodiment, F _NO = 2.6 and the focal length f
= 25.91, angle of view 2w = 48.2 °, and is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 8 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the fourth embodiment.

Next, specific numerical values are shown in Table 4.

[0098]

Conditional expression (1): Σ (1 / (fi × vi)) = − 0.000052 Conditional expression (2): fG2 / bf = 1.248 Conditional expression (3): rG2 / tG2p = −31.439 Conditional expression (4) ): FG1 / fG2 = 1.026695 Conditional expression (5): n24 = 1.8042 f = 25.91 fNo = 2.6 2w = 48.2 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νdr 1 = 70.583 d 1 = 2.8 n 1 = 1.80420 v 1 = 46.50 r 2 = 21.452 d 2 = 16.8 r 3 = 109.646 d 3 = 4.1 n 2 = 1.74950 v 2 = 35.04 r 4 = -37.770 d 4 = 0.4 r 5 = 19.603 d 5 = 4.1 n 3 = 1.77250 v 3 = 49.62 r 6 = 23.537 d 6 = 10.5 r 7 = -50.853 d 7 = 2.0 n 4 = 1.84666 v 4 = 23.78 r 8 = 32.176 d 8 = 5.1 r 9 = -627.748 d 9 = 1.3 n 5 = 1.84666 v 5 = 23.78 r10 = 40.025 d10 = 8.5 n 6 = 1.60311 v 6 = 60.69 r11 = -24.364 d11 = 1.0 r12 = 43.612 d12 = 5.9 n 7 = 1.80420 v 7 = 46.50 r13 = -85.788 d13 = 8.0 r14 = 0.000 d14 = 24.0 n 8 = 1.51680 v 8 = 64.20 r15 = 0.000 d15 = 4.1

(Embodiment 5) A projection lens according to Embodiment 5 of the present invention will be described with reference to the drawings.
FIG. 9 is a configuration diagram of a projection lens according to the fifth embodiment.

The projection lens of the fifth embodiment includes, in order from the screen S side, a negative meniscus eleventh lens L11 having a convex surface facing the screen side, a negative twelfth lens L12 having a convex surface facing the screen side, And the negative thirteenth lens L13
A first lens group G1 having a cemented lens in which a positive lens and a positive fourteenth lens L14 are cemented, and having a positive refractive power as a whole
, Aperture SP, a negative twenty-first lens L21, a cemented lens obtained by cementing a positive twenty-second lens L22 and a negative twenty-third lens L23, a positive twenty-fourth lens L24, and a positive twenty-fifth lens L25
And the second group lens G having a positive refractive power as a whole
And 2.

The refractive index of the thirteenth lens L13 is n13,
When the refractive index of the lens L14 is n14, the Abbe number of the thirteenth lens L13 is v13, and the Abbe number of the fourteenth lens is v14, (6) | n13-n14 | <0.015 (7) | v13-v14 | It is preferable to satisfy <10.

Equations (6) and (7) are for the thirteenth lens L13
And the relationship between the refractive index of the fourteenth lens L14 and the Abbe number is appropriately defined.

When the refractive indices and Abbe numbers of the thirteenth lens and the fourteenth lens satisfy the expressions (6) and (7), it is possible to prevent the chromatic aberration of magnification from being overcorrected at the place where the angle of view is large. Thus, it is possible to realize a projection lens in which chromatic aberration of magnification is satisfactorily corrected from a small angle to a large angle of view.

When | n13−n14 | exceeds the upper limit of the equation (6), the refractive power of the cemented surface between the thirteenth lens and the fourteenth lens becomes too large, and the chromatic aberration of magnification at a small angle of view becomes insufficiently corrected. Not.

When | v13−v14 | exceeds the upper limit of the expression (7), the refractive power of the cemented surface between the thirteenth lens and the fourteenth lens becomes too large, and the chromatic aberration of magnification at a small angle of view is insufficiently corrected, which is not appropriate. Not.

Then, the projection lens of the fifth embodiment is
It satisfies the relationship of the conditional expression (2) described above.

As a result, the longitudinal chromatic aberration and the chromatic aberration of magnification can be satisfactorily corrected, and a good image can be provided in the entire screen range.

Embodiment 5 will be described below as a specific numerical example of the present invention.

(Embodiment 5) FIG. 9 shows Embodiment 5 of the present invention.
12 is a configuration diagram of a projection lens according to Example 5 of FIG.

In the fifth embodiment, F _NO = 2.1 and the focal length f
= 22.39, an angle of view 2w = 55.7 °, and is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 10 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the fifth embodiment.

Next, specific numerical values are shown in Table 5.

[0113]

Table 5 Conditional expression (1): Σ (1 / (fi × vi)) = 0.00056 Conditional expression (2): fG2 / bf = 1.015 Conditional expression (3): rG2 / tG2p = −4.455 Conditional expression (4) : FG1 / fG2 = 2.763 Conditional expression (6): | n13-n14 | = 0.01232 Conditional expression (7): | v13-v14 | = 8.43 f = 22.39 fNo = 2.1 2w = 55.7 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 42.925 d 1 = 1.0 n 1 = 1.49700 v 1 = 81.61 r 2 = 19.246 d 2 = 5.3 r 3 = 74.703 d 3 = 1.1 n 2 = 1.69680 v 2 = 55.46 r 4 = 24.272 d 4 = 8.9 r 5 = 51.785 d 5 = 2.0 n 3 = 1.76182 v 3 = 26.61 r 6 = 23.508 d 6 = 8.0 n 4 = 1.74950 v 4 = 35.04 r 7 = -41.219 d 7 = 18.6 r 8 =- 49.744 d 8 = 1.5 n 5 = 1.62004 v 5 = 36.37 r 9 = 57.501 d 9 = 4.0 r10 = -82.135 d10 = 8.5 n 6 = 1.77250 v 6 = 49.62 r11 = -14.410 d11 = 1.2 n 7 = 1.84666 v 7 = 23.78 r12 = -34.196 d12 = 1.0 r13 = -547.038 d13 = 5.1 n 8 = 1.77250 v 8 = 49.62 r14 = -39.675 d14 = 0.5 r15 = 61.196 d15 = 4.4 n 9 = 1.83400 v 9 = 37.34 r16 = 531.419 d16 = 7.0 r17 = 0.000 d17 = 25.0 n10 = 1.51680 v10 = 64.20 r18 = 0.000 d18 = 7.7

Embodiment 6 A projection lens according to Embodiment 6 of the present invention will be described with reference to the drawings.
FIG. 11 is a configuration diagram of a projection lens according to the sixth embodiment.

In the sixth embodiment, by appropriately arranging the lenses, a projection lens capable of satisfactorily correcting lateral chromatic aberration and distortion while having a long back focus with telecentricity is realized.

In order to provide telecentricity, in the second group lens G2 on the side of the spatial light modulator B from the stop SP, the principal ray height is the same as the maximum image height. Therefore the second
The lens group has a large effect on distortion and axial chromatic aberration. In particular, distortion is greatly affected by the shape of each lens constituting the second group lens.

In the sixth embodiment, the value of the radius of curvature rG2 of the surface on the screen side of the negative lens having the concave surface facing the screen in the second group lens is set to be appropriate. By doing so, the incident angle of the chief ray on the screen side surface of the negative lens with the concave surface facing the screen side is constant at a small value from a small angle of view to a large angle of view, and distortion is good. Can be corrected.

The lateral chromatic aberration in the second lens unit is corrected by a lens having a negative refractive power. The greater the angle of incidence of the principal ray on the lens surface of a lens having a negative refractive power, the greater the amount of correction of lateral chromatic aberration. In addition, as the height of the principal ray on the lens surface of the lens having a negative refractive power increases, the amount of correction of the chromatic aberration of magnification increases. Due to the effects of these two corrections, the chromatic aberration of magnification is overcorrected at the maximum angle of view, and the chromatic aberration of magnification with respect to the blue light having a short wavelength is greatly overcorrected at the maximum angle of view.

The projection lens according to the sixth embodiment includes, in order from the screen S side, a cemented lens obtained by cementing a negative eleventh lens L11 and a positive twelfth lens L12, and a meniscus negative lens having a convex surface facing the screen side. A first group lens G1 having a thirteenth lens L13, a meniscus negative fourteenth lens L14 having a convex surface facing the screen side, and a positive fifteenth lens L15, and having a negative refractive power as a whole; Aperture SP,
A cemented lens obtained by cementing a negative twenty-first lens L21 and a positive twenty-second lens L22, a positive twenty-third lens L23, and a positive second lens
A second group lens G2 having four lenses L24 and having a positive refractive power as a whole.

Then, the projection lens of the sixth embodiment is
The relationship of the conditional expression (3) is satisfied.

As a result, it is possible to satisfactorily correct the distortion and the chromatic aberration of magnification, and to provide a good image over the entire screen range.

The equation (3) shows that the curvature radius rG2 of the screen side surface of the negative lens having the concave surface facing the screen side in the second group lens is on the optical axis from the screen side focal position of the second group lens. Is an equation relating to the ratio rG2 / tG2p to the distance tG2p to the vertex of the screen-side surface of the negative lens having the concave surface facing the screen in the second group lens, as measured by: If the ratio rG2 / tG2p exceeds the upper limit, distortion and chromatic aberration of magnification are insufficiently corrected, which is not appropriate. If the lower limit is exceeded, lateral chromatic aberration with respect to a blue light beam having a short wavelength becomes excessively corrected at the maximum angle of view, which is not appropriate.

Embodiment 6 is shown below as a specific numerical example of the present invention.

(Embodiment 6) FIG. 11 is a structural view of a projection lens according to Embodiment 6 of Embodiment 6 of the present invention.

In the sixth embodiment, F _NO = 2.1 and the focal length f
= 20.11, angle of view 2w = 59.9 °, and is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 12 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the sixth embodiment.

Next, specific numerical values are shown in Table 6.

[0128]

Table 6 Conditional expression (1): Σ (1 / (fi × vi)) = 0.0014408 Conditional expression (2): fG2 / bf = 0.328 Conditional expression (3): rG2 / tG2p = −1.591 Conditional expression (4) : FG1 / fG2 = 3.844 f = 20.11 fNo = 2.1 2w = 59.9 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 40.000 d 1 = 1.5 n 1 = 1.60311 v 1 = 60.69 r 2 = 25.000 d 2 = 5.0 n 2 = 1.80610 v 2 = 33.27 r 3 = 85.201 d 3 = 1.0 r 4 = 31.305 d 4 = 1.0 n 3 = 1.50913 v 3 = 56.47 r 5 = 10.000 d 5 = 5.0 r 6 = 33.876 d 6 = 1.0 n 4 = 1.50913 v 4 = 56.47 r 7 = 14.117 d 7 = 7.0 r 8 = -113.822 d 8 = 2.2 n 5 = 1.50913 v 5 = 56.47 r 9 = -20.627 d 9 = 14.1 r10 = -25.000 d10 = 1.0 n 6 = 1.84666 v 6 = 23.83 r11 = 250.000 d11 = 6.0 n 7 = 1.77 250 v 7 = 49.62 r12 = -16.782 d12 = 0.8 r13 = 88.817 d13 = 4.5 n 8 = 1.50913 v 8 = 56.47 r14 = -56.567 d14 = 2.4 r15 = -54.605 d15 = 6.0 n 9 = 1.50913 v 9 = 56.47 r16 = -31.033 d16 = 6.0 r17 = 0.000 d17 = 24.0 n10 = 1.51680 v10 = 64.20 r18 = 0.000 d18 = 5.6 Aspherical surface coefficient A4 = 2.49143E-005, A6 = -5.88755E-008 6 Aspherical surface coefficient A4 = -7.16565E-005 Nine aspherical surface coefficient A4 = -3.50118E-005, A6 = -1.89030E-007 Thirteenth surface aspherical surface coefficient A4 = -3.00515E-005, A6 =- 1.99981E-007, A8 = 3.95053E-010, A10 = -4.59567E-012 Aspherical surface coefficient of 15 planes A4 = -6.86098E-006, A6 = 7.68050E-008, A8 = 5.99441E-010, A10 =- 1.94784E-012 16 aspherical surface coefficients A4 = -2.09808E-005

Embodiment 7 A projection lens according to Embodiment 7 of the present invention will be described with reference to the drawings.
FIG. 13 is a configuration diagram of a projection lens according to the seventh embodiment.

In the seventh embodiment, by appropriately arranging the lenses, a projection lens is realized which can favorably correct lateral chromatic aberration and distortion while having telecentricity and a long back focus.

The projection lens according to the seventh embodiment includes, in order from the screen S side, a negative meniscus eleventh lens L11 having a convex surface facing the screen side, a negative twelfth lens L12 having a convex surface facing the screen side, And the positive thirteenth lens L13
And the first group lens G having a positive refractive power as a whole
1, a stop SP, a positive twenty-first lens L21, a negative twenty-second lens
A cemented lens obtained by cementing the lens L22 and the positive twenty-third lens L23, a positive twenty-fourth lens L24, and a positive twenty-fifth lens L
And a second group lens G2 having a positive refractive power as a whole.

In order to correct astigmatism, distortion, and spherical aberration, it is preferable that each of the first group lens G1 and the second group lens G2 includes at least one aspheric surface.

In order to correct astigmatism and distortion,
It is preferable that the twelfth lens L12 of the first group lens is formed of an aspheric surface.

In order to correct spherical aberration, it is preferable that the twenty-first lens L21 of the second group lens is constituted by an aspheric surface.

In order to correct longitudinal chromatic aberration and lateral chromatic aberration, the Abbe number of the twenty-fifth lens L25 is preferably 40 or less.

The correction of the chromatic aberration in the second lens unit is performed by the 22nd lens L22 having a negative refractive power. If the negative refractive power of the 22nd lens L22 is defined in order to achieve good lateral chromatic aberration at a small angle of view, lateral chromatic aberration will be overcorrected at the maximum angle of view. In the 25th lens L25, since the principal ray height at a small angle of view and the principal ray height at a large angle of view are relatively far from each other, the amount of chromatic aberration of magnification differs between the small angle of view and the maximum angle of view.

As in the seventh embodiment, the twenty-fifth lens L25
Is formed with an Abbe number of 40 or less, since the chromatic aberration of magnification at the maximum angle of view in the 25th lens is larger than the chromatic aberration of magnification at the small angle of view, good chromatic aberration of magnification is achieved in the entire projection lens.

The projection lens according to the seventh embodiment is constructed as follows.
The relationship of the conditional expression (3) is satisfied.

As a result, it is possible to satisfactorily correct the distortion and the chromatic aberration of magnification, and to provide a good image over the entire screen range.

Embodiment 7 is shown below as a specific numerical example of the present invention.

(Embodiment 7) FIG. 13 is a structural view of a projection lens according to Embodiment 7 of Embodiment 7 of the present invention.

In the seventh embodiment, F _NO = 2.1 and the focal length f
= 20.00, angle of view 2w = 61.1 °, and is a design example aiming to have a long back focus and telecentricity, and to correct lateral chromatic aberration and distortion.

FIG. 14 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the seventh embodiment.

Next, specific numerical values are shown in Table 7.

[0145]

Table 7 Conditional expression (1): Σ (1 / (fi × vi)) = 0.000204 Conditional expression (2): fG2 / bf = 0.927 Conditional expression (3): rG2 / tG2p = −1.278 Conditional expression (4) : FG1 / fG2 = 4.081 f = 20.00 fNo = 2.1 2w = 61.1 Axis between surfaces Surface radius (mm) Directional distance (mm) Nd νd r 1 = 31.916 d 1 = 2.0 n 1 = 1.69680 v 1 = 55.46 r 2 = 18.155 d 2 = 5.8 r 3 = 178.381 d 3 = 2.0 n 2 = 1.50913 v 2 = 56.47 r 4 = 17.566 d 4 = 9.3 r 5 = 33.874 d 5 = 7.5 n 3 = 1.80610 v 3 = 33.27 r 6 = -72.842 d 6 = 20.0 r 7 = -257.126 d 7 = 4.0 n 4 = 1.50913 v 4 = 56.47 r 8 = -40.240 d 8 = 2.0 r 9 = -16.714 d 9 = 1.5 n 5 = 1.84666 v 5 = 23.78 r10 = 45.739 d10 = 10.0 n 6 = 1.60311 v 6 = 60.69 r11 = -25.472 d11 = 1.0 r12 = -375.782 d12 = 6.0 n 7 = 1.49700 v 7 = 81.61 r13 = -28.257 d13 = 1.0 r14 = 42.050 d14 = 6.0 n 8 = 1.80610 v 8 = 33.27 r15 = -1379.597 d15 = 7.0 r16 = 0.000 d16 = 24.0 n 9 = 1.51680 v 9 = 64.20 r17 = 0.000 d17 = 7.7 Aspherical coefficients of three surfaces A4 = 4.92395E-005, A6 = -3.26019E- 007, A8 = 1.10722E-009, A10 = -1.71722E-012 Aspherical surface coefficient of 4 surfaces A4 = 3.83735E-005, A6 = -4.15605E-007, A8 = 1.10606E-009, A10 = -2.66804E-012 Aspherical surface coefficient of 7 surfaces A4 = 9.28236E-005, A6 = 3.72724E-007, A8 = -4.25694E-010, A10 = -1.72747E-012 Aspherical surface coefficient of 8 planes A4 = 9.03310E-005, A6 = 2.56394E-007, A8 = 2.87608E-009, A10 =- 1.14709E-011

(Eighth Embodiment) A projection lens according to an eighth embodiment of the present invention will be described with reference to the drawings.
FIG. 15 is a configuration diagram of a projection lens according to the eighth embodiment.

In the eighth embodiment, by appropriately arranging the lenses, a projection lens that can favorably correct lateral chromatic aberration and distortion while having telecentricity and a long back focus is realized.

The projection lens according to the eighth embodiment includes, in order from the screen S side, an eleventh positive lens L11 and a negative first lens L11.
A first lens group G1 having two lenses L12 and having a negative refractive power as a whole, a stop SP, and a positive twenty-first lens L2
1. A second group lens G2 having a negative second lens L22, a positive twenty-third lens L23, and a positive twenty-fourth lens L24, and having a positive refractive power as a whole.

In order to correct astigmatism and distortion,
It is preferable that the twelfth lens L12 of the first group lens is formed of an aspheric surface.

In order to correct the spherical aberration, it is preferable that the 21st lens L21 of the second group lens is constituted by an aspheric surface.

In order to correct spherical aberration and astigmatism,
It is preferable that the twenty-third lens L23 of the second group lens is constituted by an aspheric surface.

The projection lens according to the eighth embodiment has the following construction.
The relationship of the conditional expression (3) is satisfied.

As a result, the distortion and the chromatic aberration of magnification can be satisfactorily corrected, and a good image can be provided over the entire screen range.

An eighth embodiment will be shown below as a specific numerical example of the present invention.

(Eighth Embodiment) FIG. 15 is a structural view of a projection lens according to an eighth embodiment of the eighth embodiment of the present invention.

In the eighth embodiment, F _NO = 2.1 and the focal length f
= 20.36, angle of view 2w = 60.2 °, and is a design example aiming to have a long back focus and telecentricity, and to correct chromatic aberration and distortion of magnification.

FIG. 16 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the eighth embodiment.

Table 8 shows specific numerical values.

[0159]

Table 8 Conditional expression (1): Σ (1 / (fi × vi)) = 0.000655 Conditional expression (2): fG2 / bf = 0.9887 Conditional expression (3): rG2 / tG2p = −1.132 Conditional expression (4) : FG1 / fG2 = 1.896 f = 20.36 fNo = 2.1 2w = 60.2 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 33.783 d 1 = 6.0 n 1 = 1.80610 v 1 = 33.27 r 2 = 66.596 d 2 = 2.0 r 3 = 88.491 d 3 = 2.5 n 2 = 1.50913 v 2 = 56.47 r 4 = 11.923 d 4 = 27.9 r 5 = -36.634 d 5 = 7.0 n 3 = 1.50913 v 3 = 56.47 r 6 =- 14.628 d 6 = 11.4 r 7 = -23.339 d 7 = 1.4 n 4 = 1.84666 v 4 = 23.78 r 8 = 889.586 d 8 = 2.0 r 9 = 221.485 d 9 = 8.0 n 5 = 1.50913 v 5 = 56.47 r10 = -17.379 d10 = 0.6 r11 = 47.697 d11 = 5.7 n 6 = 1.77250 v 6 = 49.62 r12 = -199.689 d12 = 7.0 r13 = 0.000 d13 = 25.0 n 7 = 1.51680 v 7 = 64.20 r14 = 0.000 d14 = 7.2 Aspheric coefficient of three surfaces A4 = 2.21539E-005, A6 = -4.46246E-008, A8 = 5.05906E-011 Aspherical surface coefficient of four surfaces A4 = 1.88427E-005 Aspherical surface coefficient of five surfaces A4 = -3.98463E-005, A6 = 2.19711 E-007, A8 = -1.40310E-009 A4 = 1.21577E-005, A6 = 1.44062E-007, A8 = 2.31847E-010 Aspherical coefficient of 9 planes A4 = -6.68242E-006 Aspherical coefficient of 10 planes A4 = 4.18692E-006, A6 = 1.55500E-009, A8 = 3.94440E-011

Embodiment 9 A projection lens according to Embodiment 9 of the present invention will be described with reference to the drawings.
FIG. 17 is a configuration diagram of a projection lens according to the ninth embodiment.

In the ninth embodiment, by appropriately arranging the lenses, a projection lens which has telecentricity and a long back focus and which can satisfactorily correct distortion is realized.

In general, it is known that, in order to satisfactorily correct distortion, it is preferable to form a lens symmetrically with respect to the stop.

In order to obtain a back focus longer than the focal length, a retrofocus lens is required. That is, the front group has a negative refractive power, and the rear group has a positive refractive power.
In order to further obtain telecentricity, an aperture is arranged at a focal position on the screen side of the rear group. This lens configuration has negative refractive power on the front side of the stop and positive refractive power on the back side of the stop, so basically the front group produces negative distortion and the rear group produces negative distortion. I do.

In the ninth embodiment, the ratio fG1 / fG2 of the focal length fG1 of the first group lens G1 and the focal length fG2 of the second group lens G2 is appropriately defined. By doing so, positive distortion occurs in the first group lens G1 closer to the screen than the stop SP, and negative distortion occurs in the second group lens G2 closer to the spatial light modulator B than the stop SP. In the whole projection lens, distortion is satisfactorily corrected.

The projection lens of the ninth embodiment includes, in order from the screen S side, a meniscus negative eleventh lens L11, a positive twelfth lens L12 and a negative thirteenth lens L13 having a convex surface facing the screen side. , A first lens group G1 having a positive refractive power as a whole, a stop SP, and a meniscus negative twenty-first lens having a convex surface facing the screen side. Lens L21, a cemented lens formed by cementing a negative twenty-second lens L22 and a positive twenty-third lens L23, a positive twenty-fourth lens L24, and a positive twenty-fifth lens
A second lens L25 having a positive refractive power as a whole
And a group lens G2.

The projection lens of the ninth embodiment is
It satisfies the relationship of the conditional expression (4).

As a result, distortion can be satisfactorily corrected, and a good image can be provided over the entire screen range.

Equation (4) gives the focal length fG of the second lens unit.
The ratio fG1 / of the focal length fG1 of the first lens unit to f2
This is an expression related to fG2. If the ratio fG1 / fG2 exceeds the upper limit, the distortion is insufficiently corrected, which is not appropriate. If the lower limit is exceeded, the back focus is not secured and is not appropriate.

When the distance from the first surface on the screen side of the first lens unit to the final surface on the spatial light modulator side is D1, and the projection distance of the entire projection lens is f, (8) 1.5 <D /F<2.5 is preferably satisfied.

The above equation (8) gives the total length D1 of the first lens unit.
And the focal length f of the entire projection lens is appropriately defined.

When the total length of the first lens unit satisfies the expression (8), it is possible to realize a projection lens in which distortion is well corrected.

If the ratio D / f exceeds the upper limit of the equation (8), the overall length of the lens becomes longer and the lens diameter becomes larger, which is not appropriate. If the lower limit is exceeded, the back focus becomes short, which is not appropriate.

The refractive index of the twenty-fourth lens L24 is n24,
When the refractive index of the lens L25 is n25, it is preferable that (9) 2.5 <n24 + n25 is satisfied.

The above equation (9) appropriately defines the sum of the refractive indices of the twenty-fourth lens L24 and the twenty-fifth lens L25 having positive refracting power on the spatial light modulator side of the projection lens. is there.

When the sum n24 + n25 of the refractive indices of the twenty-fourth lens L24 and the twenty-fifth lens L25 satisfies the expression (9), a projection lens whose astigmatism has been well corrected can be realized.

If the sum n24 + n25 is below the lower limit of the expression (9), the astigmatism cannot be corrected, which is not appropriate.

The projection lens of the ninth embodiment is
It satisfies the relationship of the conditional expression (4).

As a result, it is possible to satisfactorily correct distortion and provide a good image over the entire screen range.

Embodiment 9 is shown below as a specific numerical example of the present invention.

(Embodiment 9) FIG. 17 is a structural view of a projection lens according to Embodiment 9 of Embodiment 9 of the present invention.

In the ninth embodiment, F _NO = 2.1, focal length f
= 21.93, 2w = 56.6 °, and is a design example for long back focus, telecentricity, and correction of lateral chromatic aberration and distortion.

FIG. 18 shows the spherical aberration (mm), astigmatism (mm), distortion (%), and chromatic aberration of magnification (mm) of the projection lens of the ninth embodiment.

Table 9 shows specific numerical values.

[0184]

Table 9 Conditional expression (1): Σ (1 / (fi × vi)) = − 0.000246 Conditional expression (2): fG2 / bf = 1.08 Conditional expression (3): rG2 / tG2p = −0.769 Conditional expression (4 ): FG1 / fG2 = 1.89 Conditional expression (8): D / f = 1.909 Conditional expression (9): n24 + n25 = 3.6084 f = 21.93 fNo = 2.1 2w = 56.6 Axis between surfaces Surface radius (mm) Direction distance (mm) Nd νd r 1 = 31.589 d 1 = 2.0 n 1 = 1.69680 v 1 = 55.46 r 2 = 18.045 d 2 = 6.6 r 3 = 57.928 d 3 = 7.0 n 2 = 1.80610 v 2 = 40.73 r 4 = -48.274 d 4 = 1.7 n 3 = 1.49700 v 3 = 81.61 r 5 = 19.942 d 5 = 12.1 r 6 = 39.462 d 6 = 12.5 n 4 = 1.64850 v 4 = 53.03 r 7 = -29.994 d 7 = 4.5 r 8 = 56.497 d 8 = 2.8 n 5 = 1.62004 v 5 = 36.30 r 9 = 21.274 d 9 = 4.6 r10 = -11.752 d10 = 1.3 n 6 = 1.84666 v 6 = 23.78 r11 = -253.077 d11 = 6.5 n 7 = 1.60311 v 7 = 60.69 r12 = -16.120 d12 = 0.2 r13 = -105.774 d13 = 4.3 n 8 = 1.80420 v 8 = 46.50 r14 = -29.569 d14 = 1.0 r15 = 54.511 d15 = 5.3 n 9 = 1.80420 v 9 = 46.50 r16 = -104.288 d16 = 7.0 r17 = 0.000 d17 = 24.0 n10 = 1.51680 v10 = 64.20 r18 = 0.000 d18 = 6.1

(Embodiment 10) FIG. 19 is a configuration diagram of an image enlargement projection system according to Embodiment 10 of the present invention. The image expansion projection system according to the tenth embodiment includes the projection lens A according to any one of the first to ninth embodiments, a spatial light modulator B that forms an optical image, and a light source C. P
Is a focus plane of an image projected by the present image enlargement projection system. According to the tenth embodiment, the optical image formed on the spatial light modulator B illuminated by the light source C is enlarged and projected on the focus plane P by the projection lens A. By using the projection lens described in the first to ninth embodiments as the projection lens A, it is possible to obtain an image enlargement projection system in which color bleeding is less likely.

(Embodiment 11) FIG. 20 is a configuration diagram of a video projector according to Embodiment 11 of the present invention. The video projector according to the eleventh embodiment includes a projection lens A according to any one of the first to ninth embodiments, a spatial light modulator B that forms an optical image, a light source C, blue (B), and green (G). , Red (R) fan-shaped filters, and by rotating these, the light from the light source C is sequentially switched to blue, green, and red color lights in time order and emitted by color separation means D. Be composed. The white light from the light source C is temporally separated by the color separation means D into three color lights of blue, green and red, and illuminates the spatial light modulator B. The spatial light modulator B is formed by temporally dividing three types of optical images of blue, green, and red corresponding to the illuminated color light. The three optical images of blue, green, and red formed on the spatial light modulator B are enlarged and projected by the projection lens A. By using the projection lens described in any one of Embodiments 1 to 9 as the projection lens A, a video projector which can obtain a bright and high-definition image with little color blur and distortion can be realized.

In FIG. 20, two color lights of blue, green and red are temporally switched and sequentially made incident on one spatial light modulation element B, and an optical image formed on the spatial light modulation element B is made incident. A video projector that displays a color image by switching according to the color light to be emitted has been exemplified. However, the video projector of the present invention is not limited to the configuration in which color display is performed by using one spatial light modulation element B, and uses, for example, three spatial light modulation elements corresponding to blue, green, and red, respectively. The display may be configured. That is, the color separation means D is constituted by a well-known optical system using a dichroic mirror and a reflection mirror to separate white light into three color lights of blue, green and red, and to perform three spatial light modulations with each color light. Each element is illuminated. The three spatial light modulators each form an optical image corresponding to the illuminated color light. Each optical image on the three spatial light modulators is synthesized by a well-known color synthesizing unit using a dichroic prism, and is enlarged and projected through a projection lens A. In a video projector having such a configuration, the projection lens A
By using the projection lens described in Embodiments 1 to 9 above, a video projector that can obtain a bright, high-definition image with little color blur and distortion can be realized.

(Twelfth Embodiment) FIG. 21 is a configuration diagram of a rear projector according to a twelfth embodiment of the present invention. The rear projector according to the twelfth embodiment includes the video projector G described in the eleventh embodiment, a mirror H that bends light, a transmission screen I, and a housing J. The image projected from the video projector G is reflected by the mirror H and is imaged on the transmission screen I. According to such a twelfth embodiment, by using the video projector described in the eleventh embodiment as the video projector G, the depth and height of the set can be reduced, and a compact video projector can be realized.

(Thirteenth Embodiment) FIG. 22 is a configuration diagram of a multi-vision system according to a thirteenth embodiment of the present invention. The multi-vision system according to the thirteenth embodiment includes:
A plurality of units each including the video projector G described in the eleventh embodiment, the transmissive screen I, and the housing K holding the same are provided, and further, a video dividing circuit L for dividing a video is provided. The video signal is processed and divided by a video dividing circuit L, and a plurality of video projectors G
Sent to The image projected from the video projector G is formed on the transmission screen I. According to the thirteenth embodiment, by using the video projector shown in the eleventh embodiment as the video projector G, a multi-vision system capable of displaying a large image in a compact set having a short depth can be realized.

[0190]

As described above, according to the present invention, since the lens configuration is appropriately set, the projection distance is short,
It is possible to provide a projection lens capable of realizing an image having a long back focus and little color blur and distortion.

The present invention also provides an image enlargement projection system, a video projector, a rear projector, and a multi-vision system that can realize a bright, high-quality large-screen image in a compact manner by using such a projection lens. Can be.

[Brief description of the drawings]

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

FIG. 2 is an aberration diagram of the projection lens according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a projection lens according to Example 2 of Embodiment 2 of the present invention.

FIG. 4 is an aberration diagram of a projection lens according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a projection lens according to Example 3 of Embodiment 3 of the present invention.

FIG. 6 is an aberration diagram of a projection lens according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a projection lens according to Example 4 of Embodiment 4 of the present invention.

FIG. 8 is an aberration diagram of a projection lens according to a fourth embodiment of the present invention.

FIG. 9 is a configuration diagram of a projection lens according to Example 5 of Embodiment 5 of the present invention.

FIG. 10 is an aberration diagram of a projection lens according to a fifth embodiment of the present invention.

FIG. 11 is a configuration diagram of a projection lens according to Example 6 of Embodiment 6 of the present invention.

FIG. 12 is an aberration diagram of a projection lens according to a sixth embodiment of the present invention.

FIG. 13 is a configuration diagram of a projection lens according to Example 7 of Embodiment 7 of the present invention.

FIG. 14 is an aberration diagram of a projection lens according to a seventh embodiment of the present invention.

FIG. 15 is a configuration diagram of a projection lens according to Example 8 of Embodiment 8 of the present invention.

FIG. 16 is an aberration diagram of a projection lens according to Example 8 of the present invention.

FIG. 17 is a configuration diagram of a projection lens according to Example 9 of Embodiment 9 of the present invention.

FIG. 18 is an aberration diagram of a projection lens according to a ninth embodiment of the present invention.

FIG. 19 is a configuration diagram of a video enlarged projection system according to a tenth embodiment of the present invention.

FIG. 20 is a configuration diagram of a video projector according to Embodiment 11 of the present invention.

FIG. 21 is a configuration diagram of a rear projector according to Embodiment 12 of the present invention.

FIG. 22 is a configuration diagram of a multi-vision system according to Embodiment 13 of the present invention.

[Explanation of symbols]

 Reference Signs List A projection lens B spatial light modulator C light source D color separation means G video projector GB prism H mirror I transmissive screen J housing K housing L video dividing circuit S screen SP aperture P Focus plane of projected video

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/00 G03B 21/00 E H04N 5/74 H04N 5/74 A F term (Reference) 2H087 KA06 LA03 NA02 PA06 PA07 PA08 PA17 PA18 PA19 PB06 PB07 PB08 PB09 QA02 QA06 QA07 QA12 QA17 QA21 QA22 QA25 QA26 QA32 QA34 QA41 QA42 QA45 QA46 RA05 RA12 RA13 RA32 RA41 5C058 EA01 EA02 EA12

Claims (24)

[Claims] 1. A projection lens for enlarging and projecting an optical image illuminated by light from a light source onto a screen, comprising, in order from the screen side, a first group lens composed of at least two lenses; Second with positive refractive power
A projection lens comprising a group lens and satisfying the following conditions. (1) −0.0004 <Σ (1 / (fi × vi)) <0.0015 where Σ (1 / (fi × vi)): the focal length of the i-th lens from the screen side is fi, and the lens is When the Abbe number of vi is 1 / (fi × vi) obtained for each lens, 1 / (fi × vi) for all lenses constituting the second group lens
Sum of 2. A projection lens for enlarging and projecting an optical image illuminated by light from a light source onto a screen, comprising, in order from the screen side, a first group lens composed of at least two lenses; Second with positive refractive power
A projection lens comprising a group lens and satisfying the following conditions. (2) 0.9 <fG2 / bf <1.3, where fG2: focal length of the second group lens bf: air-converted length of the back focus of the projection lens 3. A projection lens for enlarging and projecting an optical image illuminated by light from a light source onto a screen, comprising a first group lens composed of at least two lenses in order from the screen side; Second with positive refractive power
A projection lens comprising a group lens and satisfying the following conditions. (3) -2.0 <rG2 / tG2p <-0.65, where rG2 is the radius of curvature of the screen-side surface of the negative lens having the concave surface facing the screen, which constitutes the second lens unit, and tG2p is the second lens unit. From the focus position on the screen side of the lens,
Distance measured on the optical axis to the vertex of the screen-side surface of the negative lens having the concave surface facing the screen, which constitutes the second group lens. 4. A projection lens for enlarging and projecting an optical image illuminated by light from a light source onto a screen, comprising, in order from the screen side, a first group lens composed of at least two lenses; Second with positive refractive power
A projection lens comprising a group lens and satisfying the following conditions. (4) 0.95 <fG1 / fG2 <1.2, where fG1: focal length of the first group lens fG2: focal length of the second group lens 5. The projection lens according to claim 1, wherein said projection lens comprises an exit-side telecentric system. 6. The projection lens according to claim 6, wherein an F-number is 2.6.
The projection lens according to any one of claims 1 to 5, wherein the angle of view is 48 degrees or more. 7. In order from the screen side, a positive eleventh lens, a meniscus-shaped negative twelfth lens having a convex surface facing the screen side, and a meniscus-shaped negative thirteenth lens having a convex surface facing the screen side are provided. A first group lens having a negative refractive power as a whole; a diaphragm; a positive twenty-first lens; a cemented lens obtained by cementing a positive twenty-second lens with a negative twenty-third lens; a positive twenty-fourth lens; A projection lens, comprising: a meniscus-shaped negative twenty-fifth lens with a concave surface facing the side; and a second group lens having a positive refracting power as a whole having a positive twenty-sixth lens. 8. In order from the screen side, a positive eleventh lens, a meniscus-shaped negative twelfth lens with a convex surface facing the screen side, a meniscus-shaped negative thirteenth lens with a convex surface facing the screen side, and a positive lens A first lens unit having a negative refractive power as a whole; a stop; a negative 21st lens; a cemented lens formed by joining a positive 22nd lens and a negative 23rd lens; And a second lens group having a positive twenty-fourth lens and a positive twenty-fifth lens, and having a positive refractive power as a whole. 9. The projection lens according to claim 7, wherein the following condition is satisfied. (1) −0.0004 <Σ (1 / (fi × vi)) <0.0015 where Σ (1 / (fi × vi)): the focal length of the i-th lens from the screen side is fi, and the lens is When the Abbe number of vi is 1 / (fi × vi) obtained for each lens, 1 / (fi × vi) for all lenses constituting the second group lens
Is the sum of 10. A negative meniscus eleventh surface having a convex surface facing the screen side in order from the screen side.
A first group lens having a lens, a positive twelfth lens, a negative thirteenth lens, and a positive fourteenth lens, and having a positive refractive power as a whole; a diaphragm; a negative twenty-first lens; It has a cemented lens obtained by cementing a 22nd lens and a 23rd negative lens, a 24th positive lens, and a 25th positive lens, and has a second group lens having a positive refractive power as a whole. Projection lens. 11. A meniscus negative eleventh lens having a convex surface facing the screen side in order from the screen side.
A first group lens having a positive refractive power as a whole, including a lens, a positive twelfth lens, and a positive thirteenth lens; an aperture; a negative twenty-first lens, a negative twenty-second lens, and a positive A projection lens comprising: a cemented lens in which 23 lenses are cemented; and a second lens unit having a positive 24th lens and having a positive refractive power as a whole. 12. A meniscus negative eleventh convex surface facing the screen side in order from the screen side.
A first lens unit having a lens, a negative twelfth lens having a convex surface facing the screen side, and a cemented lens obtained by cementing a negative thirteenth lens and a positive fourteenth lens, and having a positive refractive power as a whole; , An aperture, and a negative twenty-first lens, a cemented lens obtained by cementing a positive twenty-second lens and a negative twenty-third lens, a positive twenty-fourth lens, and a positive twenty-fifth lens. And a second group lens having the following. 13. The projection lens according to claim 10, wherein the following condition is satisfied. (2) 0.9 <fG2 / bf <1.3, where fG2: focal length of the second group lens bf: air-converted length of the back focus of the projection lens 14. A cemented lens in which a negative eleventh lens and a positive twelfth lens are cemented, a meniscus-shaped negative thirteenth lens having a convex surface facing the screen side, and a convex surface facing the screen side, in order from the screen side. A first group lens having a negative meniscus negative fourteenth lens and a positive fifteenth lens, and having a negative refractive power as a whole; a diaphragm; a negative twenty-first lens and a positive twenty-second lens; A projection lens, comprising: a cemented lens, a positive twenty-third lens, and a positive twenty-fourth lens, and a second lens group having a positive refractive power as a whole. 15. A meniscus-shaped negative eleventh convex surface facing the screen side in order from the screen side.
A first group lens having a lens, a negative twelfth lens having a convex surface facing the screen side, and a positive thirteenth lens, and having a positive refractive power as a whole; a diaphragm; a positive twenty-first lens; It has a cemented lens obtained by cementing a twenty-second lens and a positive twenty-third lens, a positive twenty-fourth lens, and a positive twenty-fifth lens, and has a second group lens having a positive refractive power as a whole. Projection lens. 16. A first group lens having a positive eleventh lens and a negative twelfth lens in this order from the screen side, and having a negative refractive power as a whole, a diaphragm, a positive twenty-first lens, and a negative twenty-first lens. And a second lens group having a positive twenty-third lens, a positive twenty-third lens, and a positive twenty-fourth lens, and having a positive refractive power as a whole. 17. The projection lens according to claim 14, wherein the following condition is satisfied. (3) -2.0 <rG2 / tG2p <-0.65, where rG2 is the radius of curvature of the screen-side surface of the negative lens having the concave surface facing the screen, which constitutes the second lens unit, and tG2p is the second lens unit. From the focus position on the screen side of the lens,
The distance measured on the optical axis to the vertex of the screen side surface of the negative lens having the concave surface facing the screen side, which constitutes the second group lens. 18. A meniscus negative eleventh convex surface with a convex surface facing the screen side in order from the screen side.
A first lens unit having a lens, a cemented lens obtained by cementing a positive twelfth lens and a negative thirteenth lens, and a positive fourteenth lens, and having a positive refractive power as a whole; an aperture; Meniscus negative 21st with convex surface
A second lens unit including a lens, a cemented lens obtained by cementing a negative twenty-second lens and a positive twenty-third lens, a positive twenty-fourth lens, and a positive twenty-fifth lens, and having a positive refractive power as a whole. A projection lens comprising: 19. The projection lens according to claim 18, wherein the following condition is satisfied. (4) 0.95 <fG1 / fG2 <1.2, where fG1: focal length of the first group lens fG2: focal length of the second group lens 20. A light source, a spatial light modulator illuminated with light emitted from the light source and forming an optical image, and projection means for enlarging and projecting the optical image on the spatial light modulator, An image enlargement projection system, wherein the projection unit is the projection lens according to claim 1. 21. A light source, means for decomposing light from the light source into three color lights of blue, green and red, and illuminated by the three color lights of blue, green and red and corresponding to the illuminated color lights 20. A projection lens according to claim 1, further comprising: a spatial light modulation element that forms an optical image; and projection means for enlarging and projecting the optical image on the spatial light modulation element, wherein the projection means is the projection lens according to claim 1. A video projector. 22. The spatial light modulator according to claim 3, wherein the spatial light modulator has three colors of blue, green, and red.
22. The video projector according to claim 21, further comprising a color synthesizing unit that is provided for each of the three color lights and synthesizes three color lights of blue, green, and red emitted from each of the spatial light modulation elements. 23. A video projector according to claim 21, comprising a video projector, a mirror for bending light projected from the video projector, and a transmissive screen for projecting an image when light reflected by the mirror enters. A rear projector characterized by the above-mentioned. 24. A video dividing circuit comprising: a plurality of units each comprising the video projector according to claim 21 or 22 and a transmissive screen that projects an image by receiving light projected from the video projector; A multi-vision system comprising: