JP2001249275A - Zoom lens and projection display device with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-plate system color projector wide-angle zoom lens which is telecentric on a liquid crystal display element side, having a long back focus, having a bright F-number, whose 100-inch projection distance is almost as long as 2.5 m on a short focus side, while having good aberration characteristics, a high contrast and high resolution image forming performance. SOLUTION: The zoom lens is provided with a 1st lens group whose refractive power is negative, a 2nd lens group whose refractive power is positive, a 3rd lens group whose refractive power is negative and a 4th lens group whose refractive power is positive, in order from an enlargement side. The power is varied by moving the 2nd lens group and the 3rd lens group in the optical axis direction, and the 1st lens group is provided with at least one aspherical lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens used in a three-panel color projector using a liquid crystal display device.

[0002]

2. Description of the Related Art A projection lens used in a three-panel color projector using a liquid crystal display element has a dichroic prism for color synthesis disposed between the lens and the liquid crystal display element. Therefore, a long back focus is required. Further, since the spectral characteristics of the dichroic prism have an angle dependence, it is required that the liquid crystal display side is telecentric.

For this reason, the projection lens is generally a concave group leading four group zoom lens that can easily produce a back focus and can be miniaturized, or a convex group leading group zoom lens that can easily take a telecentric structure. It is.

[0004]

In recent years, in response to a demand for higher image quality, the number of pixels of a liquid crystal display device has been increased from 640 pixels × 480 pixels.
It has increased to 1024 pixels x 768 pixels. Therefore, in order to prevent a portion of the liquid crystal display element through which light can pass, that is, to prevent an image on a screen from being darkened by an opening, a microlens array has been arranged on an incident surface of the liquid crystal display element. As a result, the light hitting the surface other than the opening is converged on the opening by the microlens array and can pass through the opening.

However, the F-number of the light beam emitted from the liquid crystal display element becomes brighter than the F-number of the illumination light beam due to the convex lens function of the microlens array, so that the F-number required for the projection lens also becomes bright. Actually, an F-number of about 1.7 to 2.0 is required.

Further, in recent years, a liquid crystal display element having a size of 0.7 "to 0.9" has been mounted on a projector, so that the size and weight have been further reduced, and an ultra-compact, lightweight and inexpensive projector called a mobile projector has appeared. It has become

At the same time, the projection lens is also required to be small, lightweight and inexpensive. In addition, as the size of the liquid crystal display element becomes smaller, the pixel pitch becomes smaller accordingly, and a lens with higher resolution than before is required.

In addition, since a mobile projector often needs to give a presentation in a narrow place, there is a great demand for a wide-angle zoom lens that can obtain a large projection area with a short projection distance.

In view of the above, the present invention has been made in view of the above-described conventional problems, and has a liquid crystal display element that is telecentric and has a long backing while having good aberration characteristics, high contrast and high resolution imaging performance. It is an object of the present invention to provide a wide-angle zoom lens for a three-panel color projector having a focus, a bright F-number, and a projection distance of about 2.5 m for a short focal length of 100 inches.

[0010]

The first means for solving the above-mentioned problems includes, in order from the magnification side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, A third lens group having a negative refractive power and a fourth lens group having a positive refractive power, wherein the magnification is changed by moving the second lens group and the third lens group in the optical axis direction; The zoom lens according to claim 1, wherein the first lens group includes at least one aspheric lens.

There is provided a wide-angle zoom lens for a three-panel color projector in which the liquid crystal display element side is telecentric, has a long back focus, has a bright F number, and has a short focal length of 100 inches and a projection distance of about 2.5 m.
Further, the present zoom lens achieves downsizing of the lens while having high-contrast, high-resolution imaging performance with good distortion and little coma flare.

A second means for solving the above problems is that the focal length of the second lens group is f ₂ , the focal length of the entire lens system at the wide end is f _w, and the focal length of the fourth lens group is f when was the f _4, claims and characterized by satisfying the condition of _{1.2 <f 2 / f w <} 2.5 (1) 1.3 <f 4 / f w <2.5 (2) A zoom lens according to claim 1 (claim 2).

By satisfying this condition, it is possible to maintain good field curvature while maintaining telecentricity and a long back focus.

When the lower limit of conditional expression (1) is exceeded, it becomes difficult to obtain a predetermined back focus. Further, the refractive power of the second lens group becomes too strong, and it becomes difficult to correct the field curvature. If the upper limit is exceeded, the amount of movement of the second lens group will be large, and the overall length of the lens will be too long. If the lower limit of conditional expression (2) is exceeded, it becomes difficult to obtain a predetermined back focus. Further, the refractive power of the fourth lens group becomes too strong, and it becomes difficult to correct the field curvature. Also,
If the upper limit is exceeded, the air gap between the third lens unit and the fourth lens unit must be increased in order to secure telecentricity, and the overall length of the lens increases.

The third means for solving the above problem further satisfies a condition of 0.92 <f ₂ / f ₄ <1.20 (3). This is a zoom lens (claim 3).

By satisfying this condition, both telecentricity and back focus can be ensured in a well-balanced manner.

If the refracting power of the second lens unit is increased beyond the lower limit of the conditional expression (3), it becomes difficult to secure the back focus. If the refractive power of the fourth lens unit is increased beyond the upper limit, the effective diameter of the first lens unit must be increased in order to secure telecentricity, resulting in an increase in the size of the lens.

A fourth means for solving the above-mentioned problem is that the first lens group includes, in order from the enlargement side, a concave meniscus lens having a convex surface facing the enlargement side, a concave meniscus lens having a convex surface facing the enlargement side, and It is composed of a cemented lens of a convex meniscus lens with the convex surface facing the enlargement side, and when the Abbe number difference between two types of glass constituting the cemented lens is Δν and the refractive index difference is Δn, Δν> 35 (4) The condition of Δn> 0.3 (5) is satisfied.
The zoom lens according to any one of the above. (Claim 4).

By satisfying this condition, excellent correction of chromatic aberration of magnification and correction of coma aberration are ensured. Here, Δν is the Abbe number difference between the two types of glass constituting the cemented lens, and Δn is the refractive index difference.

If conditional expression (4) is not satisfied, it becomes difficult to correct lateral chromatic aberration at the wide-angle end. If conditional expression (5) is not satisfied, it becomes difficult to correct coma aberration at the wide-angle end, coma aberration correction at the telephoto end, and spherical aberration correction.

A fifth means for solving the above problem is a projection display device provided with a zoom lens according to any one of claims 1 to 4 (claim 5).

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projection zoom lens according to an embodiment of the present invention will be described with reference to the drawings.

The zoom lens includes, in order from the magnification side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G having a negative refractive power.
3, the fourth lens group G4 having a positive refractive power. An aperture SP is provided between the second lens group G2 and the third lens group G3. Further, outside the fourth lens group, a parallel flat glass L51 corresponding to a three-color combining prism of the projector is arranged.

The first lens group G1 includes, in order from the enlargement side, a concave meniscus lens having a convex surface facing the enlargement side, a concave meniscus lens having a convex surface facing the enlargement side, and a convex meniscus lens having a convex surface facing the enlargement side. And a cemented lens. Further, the concave surface of the concave meniscus lens is formed as an aspheric surface. The definition of the aspherical shape is given by the following equation.

[0025]

(Equation 1)

Here, X is the sag amount of the aspheric surface in the optical axis direction,
Y is the distance from the optical axis, R is the radius of curvature of the reference spherical surface, K is the eccentricity, and A _i is the i-th order aspherical coefficient.

During zooming from the wide end to the telephoto end, the first lens group G1 and the fourth lens group G4 are fixed, the second lens group G2 moves to the enlargement side, and the third lens group G2 moves to the third side.
The lens group G3 moves so as to correct the focus movement due to the movement of the second lens group G2. Then, the stop SP is moved integrally with the second lens group G2. [First Embodiment] FIG. 1 is a diagram showing a configuration of a zoom lens according to a first embodiment of the present invention.

The values of the specifications of the first embodiment are listed below.

F = 18.38 mm to 22.11 mm F _NO = 2.01 to 2.22 f ₂ = 28.56 mm f ₄ = 29.05 mm where f is the focal length of the entire optical system, and F _NO is F number, f ₂ is the focal length of the second lens group G2, f ₄ is the focal length of the fourth lens group G4.

The lens data of the first embodiment is as follows. Surface number i Curvature radius R Surface spacing D Refractive index n Abbe number ν 1 65.626 2.50 1.48749 70.2 2 19.460 * 6.00 3 59.967 2.00 1.48749 70.2 4 17.344 4.50 1.84666 23.8 5 19.167 Variable 6 34.275 2.00 1.80518 25.4 7 21.585 5.80 1.62041 60.3 8 −885.753 0.20 9 52.359 4.10 1.69680 55.5 10 −84.343 0.10 11 Aperture Variable 12 −43.301 1.50 1.48749 70.2 13 18.559 3.30 1.84666 23.8 14 31.750 Variable 15 −132.546 2.00 1.84666 23.8 16 22.836 12.00 1.48749 70.2 17 −31.731 0.20 18 283.240 6.00 1.62041 60.3 19 − 0.20 20 38.367 10.00 1.62041 60.3 21 -123.092 8.00 22 ∞ 28.20 1.51633 64.1 23 ∞ 0.12 Here, the surface number i is the number assigned to each lens surface in order from the enlargement side, and the surface distance D is the air space or lens thickness with the next surface. It is.

The radius of curvature marked with * indicates an aspherical surface. The aspheric coefficients are as follows.

[0032] Next, the focal length f of the zoom lens is set to 18.38 mm, 2
Surface spacing D when 0.31 mm and 22.11 mm are used
5, the values of the surface spacing D11 and the surface spacing D14 are as follows. Next, the value of the conditional expression is expressed as follows: f ₂ / f _w = 1.554 f ₄ / f _w = 1.581 f ₂ / f ₄ = 0.983 Δν = 46.4 Δn = 0.359 Satisfies the conditional expression.

Here, Δν is the Abbe number difference between the two types of glass constituting the cemented lens in the first lens group G1, and Δn is the refractive index difference.

FIG. 2 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 3 is a diagram showing coma aberration at the wide end of the first embodiment.

FIG. 4 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 5 is a diagram showing coma aberration at the telephoto end according to the first embodiment.

In each aberration diagram, FNO represents the F-number, A represents the angle of view at which the light beam enters the lens, and C represents the C-number.
The aberration for the line, g indicates the aberration for the g line, and e indicates the aberration for the e line.

In the aberration diagrams showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. Further, in the aberration diagram showing the spherical aberration, a broken line indicates a sine condition (sine condition).

In the aberration diagram showing coma, the solid line indicates coma in the meridional direction (M direction), and the broken line indicates coma in the sagittal direction (S direction). [Second Embodiment] FIG. 6 is a diagram showing a zoom lens configuration according to a second embodiment.

The values of the specifications of the second embodiment are listed below. _{f = 18.38mm~22.11mm F NO = 1.71~1.81 f} 2 = 35.08mm f 4 = 27.26mm where, f is the focal length of the entire optical system, F _NO is the F-number, f ₂ is the focal length of the second lens group G2, f ₄ is the focal length of the fourth lens group G4.

The lens data of the second embodiment is as follows. Surface number i Curvature radius R Surface distance D Refractive index n Abbe number ν 1 74.587 2.50 1.48749 70.2 2 19.843 * 6.00 3 49.422 2.00 1.48749 70.2 4 17.883 5.50 1.84666 23.8 5 21.220 Variable 6 −1189.589 2.00 1.80518 25.4 7 56.451 5.80 1.62041 60.3 8 − 68.748 0.20 9 31.576 5.00 1.77250 49.6 10 477.694 Variable 11 Aperture Variable 12 −40.319 1.50 1.48749 70.2 13 37.911 3.30 1.84666 23.8 14 54.945 Variable 15 412.265 2.00 1.84666 23.8 16 28.856 12.00 1.43875 95.0 17 −27.515 0.20 18 46.595 8.50 1.77472 49.6 20 51.493 5.00 1.77250 49.6 21 96.222 6.00 22 ∞ 28.20 1.51633 64.1 23 ∞ 1.26 Here, the surface number i is the number assigned to each lens surface in order from the enlargement side, and the surface interval D is the air interval or lens thickness with the next surface. .

The radius of curvature marked with * indicates an aspherical surface. The aspheric coefficients are as follows.

[0044] Next, the focal length of the zoom lens is set to 18.38 mm,
Surface spacing D when 0.31 mm and 22.11 mm are used
5, the values of the surface spacing D11 and the surface spacing D14 are as follows. Now indicates the value of the condition, becomes _{f 2 / f w = 1.909 f} 4 / f w = 1.483 f 2 / f 4 = 1.287 Δν = 46.4 Δn = 0.359, Satisfies the conditional expression. Here, Δν is the Abbe number difference between the two types of glass constituting the cemented lens in the first lens group G1, and Δn is the refractive index difference.

FIG. 7 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 8 is a diagram showing coma aberration at the wide end in the second embodiment.

FIG. 9 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 10 is a diagram showing coma aberration at the telephoto end according to the second embodiment.

In each aberration diagram, FNO represents the F number, A represents the angle of view at which the light beam enters the lens, and C represents C
The aberration for the line, g indicates the aberration for the g line, and e indicates the aberration for the e line.

In the aberration diagrams showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. Further, in the aberration diagram showing the spherical aberration, a broken line indicates a sine condition (sine condition).

In the aberration diagram showing the coma aberration, the solid line indicates the coma aberration in the median direction (M direction), and the broken line indicates the coma aberration in the sagittal direction (S direction). Third Embodiment FIG. 11 is a diagram showing a configuration of a zoom lens according to a third embodiment. The values of the specifications of the third embodiment are listed. _{f = 18.38mm~22.11mm F NO = 1.75~1.94 f} 2 = 28.06mm f 4 = 30.01mm where, f is the focal length of the entire optical system, F _NO is the F-number, f ₂ is the focal length of the second lens group G2, f ₄ is the focal length of the fourth lens group G4.

The lens data of the third embodiment is as follows. Surface number i Curvature radius R Surface spacing D Refractive index n Abbe number ν 1 61.472 2.50 1.62041 60.3 2 19.960 * 6.00 3 52.439 2.00 1.48749 70.2 4 18.048 6.00 1.84666 23.8 5 19.986 Variable 6 30.774 2.00 1.84666 23.8 7 22.432 5.80 1.48749 70.2 8 −135.170 0.20 9 49.995 4.10 1.69680 55.5 10 −79.239 0.10 11 Aperture Variable 12 −43.995 1.50 1.48749 70.2 13 16.890 3.30 1.84666 23.8 14 29.281 Variable 15 −75.545 2.00 1.84666 23.8 16 22.494 12.00 1.48749 70.2 17 −29.058 0.20 18 55.140 8.00 1.69680 55.5 19−147 0.20 20 245.606 5.00 1.62041 60.3 21 -172.494 0.20 22 63.449 6.00 1.62041 60.3 23 -981.080 8.00 24 ∞ 28.20 1.51633 64.1 25 ∞ 0.12 Here, the surface number i is the number given to each lens surface in order from the enlargement side, and the surface interval D is Is the air gap with respect to the surface or the lens thickness.

The radius of curvature marked with * indicates an aspherical surface. The aspheric coefficients are as follows.

[0054] Next, the focal length f of the zoom lens is set to 18.38 mm, 2
Surface spacing D when 0.31 mm and 22.11 mm are used
5, the values of the surface spacing D11 and the surface spacing D14 are as follows.

[0055] Now indicates the value of the condition, becomes _{f 2 / f w = 1.527 f} 4 / f w = 1.633 f 2 / f 4 = 0.935 Δν = 46.4 Δn = 0.359, Satisfies the conditional expression. Here, Δν is the Abbe number difference between the two types of glass constituting the cemented lens in the first lens group G1, and Δn is the refractive index difference.

FIG. 12 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 13 is a diagram showing coma aberration at the wide end of the second embodiment.

FIG. 14 shows (A) spherical aberration, (B) astigmatism, (C) distortion,
(D) is a diagram showing chromatic aberration of magnification.

FIG. 15 is a diagram showing the coma aberration at the telephoto end according to the second embodiment.

In each aberration diagram, FNO represents the F-number, A represents the angle of view at which the light beam enters the lens, and C represents the angle of view.
The aberration for the line, g indicates the aberration for the g line, and e indicates the aberration for the e line.

In the aberration diagrams showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. Further, in the aberration diagram showing the spherical aberration, a broken line indicates a sine condition (sine condition).

In the aberration diagram showing the coma aberration, the solid line indicates the coma aberration in the meridional direction (M direction), and the broken line indicates the coma aberration in the sagittal direction (S direction).

The zoom lens according to the present invention can be applied to, for example, a three-plate type color projector (projection display device) as shown in FIG.

FIG. 16 is a diagram schematically showing a three-plate type color projector (projection display device). 1 is a light source composed of a lamp and a concave mirror such as an ellipse or a parabolic mirror, and 2 is a cross dichroic mirror in which a red reflecting dichroic mirror 2R and a blue reflecting dichroic mirror 2B are orthogonally arranged on the optical axis in an X-shape. 3, 4, 5, and 6 are folding mirrors, 7R is a transmission light valve for red light, 7
B is a transmission light valve for blue light, 7G is a transmission light valve for green light, and 8 is a dichroic film 8B for reflecting blue light.
A cross dichroic prism, which is a composite prism formed in an x-shape such that the red light reflecting dichroic film 8R and the red light reflecting dichroic film 8R are orthogonal to each other, and a projection lens 9 are shown.

The white light source light emitted from the light source 1 is incident on the cross dichroic mirror 2, where red light is reflected by the red light mirror 2R, and blue light is reflected by the blue light mirror 2B. The green light is transmitted through the cross dichroic mirror 2.

The red light reflected by the red light mirror 2R passes through the bending mirrors 3 and 4 and enters the red light transmission type liquid crystal light valve 7R.

The blue light reflected by the blue light mirror 2B is incident on the blue light transmission type liquid crystal light valve 7B via the bending mirrors 5 and 6. The green light transmitted through the cross dichroic mirror 2 is incident on a transmissive liquid crystal light valve for green light 7G.

The transmission type liquid crystal light valves 7R, 7 for each color light
B and 7G are 2 in which liquid crystal panels are arranged in crossed Nicols.
This is a configuration sandwiched between two polarizing plates.

Therefore, of the light incident on the transmission type liquid crystal light valve for each color light, the polarizing plate disposed on the incident surface side transmits only predetermined linearly polarized light and reaches the liquid crystal panel. Of the single polarized light of each color incident on the liquid crystal panel, the light corresponding to the portion modulated by the color signal is emitted after changing the vibration direction, and the light of the non-applicable portion is unmodulated light as incident light. Emitted with the same polarized light.

The polarizing plate disposed on the exit surface side transmits and emits only the modulated light, and absorbs non-modulated light.

The transmission type liquid crystal light valves 7R, 7 for each color light
The modulated lights of the respective colors emitted from B and 7G are incident on a cross dichroic prism 8 which is a color combining optical system, and are combined.

The color synthesis is performed by reflecting the red polarized light by the dichroic film 8R, reflecting the blue modulated light by the dichroic film 8B, and transmitting the green modulated light through the dichroic films 8R and 8B.

After the color synthesis is performed, the synthesized light is emitted,
The light is incident on the zoom lens according to the present invention, and a full-color image is projected on a screen (not shown).

A microlens array may be arranged on the incident surface side of the transmission type liquid crystal light valve for each color light.

[0075]

As described above, the zoom lens according to the present invention is composed of four lens groups, and at least one surface in the first lens group is aspheric, so that the liquid crystal display element side is telecentric and long. It is possible to provide a wide-angle zoom lens for a three-panel color projector having a back focus, a bright F-number, and a projection distance of about 2.5 m for a short focal length of 100 inches.

Further, the zoom lens according to the present invention has the following conditional expression (1).
By satisfying the conditions (5) to (5), the size of the lens can be reduced while having a high-contrast and high-resolution imaging performance with good distortion and less coma flare.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a zoom lens according to a first embodiment.

FIG. 2 is a diagram illustrating (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the wide end of the zoom lens according to the first embodiment.

FIG. 3 is a diagram illustrating coma aberration at a wide end of the zoom lens according to the first embodiment.

FIG. 4 is a diagram illustrating (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the telephoto end of the zoom lens according to the first embodiment.

FIG. 5 is a diagram showing coma aberration at the telephoto end of the zoom lens according to the first embodiment.

FIG. 6 is a diagram illustrating a configuration of a zoom lens according to a second embodiment.

FIG. 7 is a diagram illustrating (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the wide end of the zoom lens according to the second embodiment.

FIG. 8 is a diagram illustrating coma aberration at a wide end of a zoom lens according to a second embodiment.

FIG. 9 is a diagram illustrating (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the telephoto end of the zoom lens according to the second embodiment.

FIG. 10 is a diagram illustrating coma aberration at the telephoto end of a zoom lens according to a second embodiment.

FIG. 11 is a diagram illustrating a configuration of a zoom lens according to a third embodiment.

FIG. 12 is a diagram illustrating (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the wide-angle end of the zoom lens according to the third embodiment.

FIG. 13 is a diagram illustrating coma aberration at a wide end of a zoom lens according to a third embodiment.

FIG. 14 is a diagram showing (A) spherical aberration, (B) astigmatism, (C) distortion, and (D) magnification chromatic aberration at the telephoto end of the zoom lens according to the third embodiment.

FIG. 15 is a diagram illustrating coma aberration at a telephoto end of a zoom lens according to a third embodiment.

FIG. 16 illustrates a zoom lens according to an embodiment of the present invention.
It is a schematic diagram of a plate type color projector (projection display device).

[Explanation of symbols]

 G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group SP Aperture 1 ... White light source 2 ... Cross dichroic mirror 3, 4, 5, 6, ... Folding mirror 8. ..Cross dichroic prism 9 ... Projection lens

Claims (5)

[Claims] 1. A first lens having a negative refractive power in order from an enlargement side.
A lens group, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. 3
A zoom lens, wherein a magnification is changed by moving a lens group in an optical axis direction, and the first lens group has at least one aspheric lens. 2. The focal length of said second lens group is f ₂ ,
When the focal length of the entire lens system at the wide end is f _w and the focal length of the fourth lens group is f ₄ , 1.2 <f ₂ / f _w <2.5 (1) 1.3 <f The zoom lens according to claim 1, wherein a condition of ₄ / _fw <2.5 (2) is satisfied. 3. The zoom lens according to claim 1, wherein a condition of 0.92 <f ₂ / f ₄ <1.20 (3) is further satisfied. 4. A concave meniscus lens having a convex surface directed to the enlargement side, a concave meniscus lens having a convex surface directed to the enlargement side, and a convex meniscus lens having a convex surface directed to the enlargement side, in order from the enlargement side. Where the Abbe number difference between the two types of glass constituting the cemented lens is Δν and the refractive index difference is Δn, Δν> 35 (4) Δn> 0.3 (5) Claims 1 to 3 are satisfied.
The zoom lens according to any one of the above. 5. A projection display device comprising the zoom lens according to claim 1.