JP2019109488A - Zoom lens for projection and projection type picture display unit - Google Patents

Abstract

To provide a negative read type novel zoom lens for projection which has a constant F value over the whole power variation range from a wide-angle end to a telephoto end.SOLUTION: A zoom lens for projection has a first lens group G1 with negative refracting power, a second lens group G2 with positive refracting power, a third lens group G3 with positive refracting power, and a fourth lens group G4 with positive refracting power arranged in order from an enlargement side to a reduction side, and also has an aperture diaphragm S fixedly arranged in the fourth lens group or on an enlargement side of the fourth lens group, and is substantially telecentric on the reduction side. For zooming, the first lens group, second lens group, and third lens group move independently along the optical axis with the fourth lens group G4 and the aperture diaphragm S fixed, and the F value is constant over the whole range of power variation by zooming.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projection zoom lens and a projection type image display apparatus.

A projection-type image display apparatus that enlarges and projects a small original image displayed on an "image display element" such as a liquid crystal display element or DMD onto a projection surface such as a screen is widely known as a projector or the like, and the distance to the projection surface Projectors equipped with a “projection zoom lens” that can change the size of a projection image without being bothered by are widely used because of their ease of use.
Conventionally, various types of projection zoom lenses have been known. However, the "negative lead" type in which the "negative refractive power lens unit" is disposed on the most enlargement side has a wide angle of view and reduction It is known that it is easy to realize optical characteristics suitable for a projection zoom lens, such as telecentricity on the side, a long back focus, and the like (for example, Patent Documents 1 to 3).

In general, in the zoom lens, the F number (numerical aperture: F number) changes due to zooming, and the F number at the telephoto end is larger than at the wide angle end and tends to be dark.
Patent Document 1 describes suppressing variation in F-number associated with zooming, and the projection zoom lenses disclosed in Patent Documents 2 and 3 suppress variation in F-number associated with zooming.

  SUMMARY OF THE INVENTION The object of the present invention is to realize a novel negative lead type four-group projection zoom lens having a constant F-number over the entire variable magnification range from the wide-angle end to the telephoto end.

  The projection zoom lens according to the present invention includes, in order from the enlargement side to the reduction side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens having positive refractive power. A fourth lens group having a positive refractive power is disposed, and an aperture stop is fixedly disposed on the enlargement side of the fourth lens group or in the fourth lens group, and the reduction side is substantially telecentric, and for zooming The fourth lens group and the aperture stop are fixed, and the first lens group, the second lens group, and the third lens group move independently in the optical axis direction, and the F value is constant in the entire variable power range by the zooming. It is.

  According to the present invention, it is possible to realize a negative lead type novel projection zoom lens having a constant F-number over the entire variable magnification range from the wide-angle end to the telephoto end.

FIG. 2 is a diagram showing lens configurations at the wide-angle end and the telephoto end of Example 1; FIG. 5 is a diagram showing spherical aberration, astigmatism and distortion at the wide-angle end in Example 1. 5 is a diagram showing coma aberration at the wide-angle end of Example 1. FIG. FIG. 5 is a diagram showing spherical aberration, astigmatism and distortion at an intermediate focal length in Example 1. 5 is a diagram showing coma aberration at an intermediate focal length of Example 1. FIG. FIG. 5 is a diagram showing spherical aberration, astigmatism, and distortion at a telephoto limit in Example 1. 5 is a diagram showing coma aberration at the telephoto end in Example 1. FIG. FIG. 7 is a diagram showing lens configurations at the wide-angle end and the telephoto end of Example 2; FIG. 7 is a diagram showing spherical aberration, astigmatism and distortion at the wide-angle end in Example 2. FIG. 7 is a diagram showing coma aberration at the wide-angle end of Example 2. FIG. 7 is a diagram showing spherical aberration, astigmatism and distortion at an intermediate focal length in Example 2. FIG. 6 is a diagram showing coma aberration at an intermediate focal length of Example 2. FIG. 7 is a diagram showing spherical aberration, astigmatism and distortion at the telephoto end in Example 2. FIG. 7 is a diagram showing coma aberration at the telephoto end in Example 2. FIG. 14 is a diagram showing lens configurations at the wide-angle end and the telephoto end of Example 3; FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at the wide-angle end in Example 3. FIG. 16 is a diagram showing coma aberration at the wide-angle end of Example 3. FIG. 16 is a diagram showing spherical aberration, astigmatism, and distortion at an intermediate focal length in Example 3. FIG. 16 is a diagram showing coma aberration at the intermediate focal length of Example 3. FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at the telephoto end in Example 3. FIG. 16 is a diagram showing coma aberration at the telephoto end in Example 3. FIG. 18 is a diagram showing lens configurations at the wide-angle end and the telephoto end of the fourth embodiment. FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at the wide-angle end in Example 4. FIG. 16 is a diagram illustrating coma aberration at the wide-angle end of Example 4. FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at an intermediate focal length in Example 4. FIG. 18 shows coma aberration at the intermediate focal length of Example 4. FIG. 16 shows spherical aberration, astigmatism and distortion at the telephoto end in Example 4. FIG. 16 is a diagram showing coma aberration at the telephoto end of Example 4. FIG. 18 shows lens configurations at the wide-angle end and the telephoto end of Example 5. FIG. 18 shows spherical aberration, astigmatism and distortion at the wide-angle end in Example 5. FIG. 18 is a diagram illustrating coma aberration at the wide-angle end of Example 5. FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at an intermediate focal length of Example 5. FIG. 16 is a diagram showing coma at an intermediate focal length of Example 5. FIG. 16 is a diagram showing spherical aberration, astigmatism and distortion at the telephoto end in Example 5. FIG. 18 is a diagram showing coma aberration at the telephoto end of Example 5. FIG. 6 is a view showing a state in which the projection zoom lens of Example 1 is focused at a projection distance of 2700 mm to 1550 mm at a wide angle end. FIG. 5 is a diagram showing spherical aberration, astigmatism, and distortion at a projection distance of 1550 mm at the wide-angle end in Example 1. FIG. 7 is a diagram showing coma aberration at a projection distance of 1550 mm at the wide-angle end in Example 1. It is a figure for demonstrating one Embodiment of a projection type image display apparatus.

  The configuration of the projection zoom lens described above, that is, “the first lens group having negative refractive power, the second lens group having positive refractive power, and the positive refractive power in order from the enlargement side to the reduction side The third lens group has a fourth lens group with positive refractive power, and the aperture stop is fixedly arranged in the fourth lens group or on the enlargement side of the fourth lens group, and the reduction side is approximately telecentric. During zooming, the fourth lens group and the aperture stop are fixed, and the first lens group, the second lens group, and the third lens group move independently in the optical axis direction, and F in the entire zoom range by the zooming A configuration in which the value is constant is referred to as “configuration 1”.

A description will be given below according to the embodiment.
FIGS. 1, 8, 15, 22 and 29 illustrate five embodiments of the projection zoom lens. Of course, the projection zoom lens according to the present invention is not limited to these embodiments. The embodiments shown in FIG. 1, FIG. 8, FIG. 15, FIG. 22, and FIG. 29 correspond to specific examples 1 to 5 described later in this order.
In these figures, the upper figure shows the "lens configuration at the wide angle end", and the lower figure shows the "lens configuration at the telephoto end". The left side of the figure is the enlargement side (projected surface side), and the right side is the reduction side (image display element side). In order to avoid complexity, the symbols are made common throughout the above figures.
That is, the first lens group, the second lens group, the third lens group, and the fourth lens group are indicated by reference numerals G1, G2, G3 and G4, and the "aperture stop" is indicated by reference numeral S. Furthermore, “image display element” is indicated by a code MD. In these embodiments, a "liquid crystal panel" is assumed as the image display element MD, and a symbol CG in the figure indicates a cover glass of the image display surface of the liquid crystal panel.
In these embodiments, it is assumed that images of red, green, and blue color components are combined to enlarge and project a color image, and the symbol P in each of the above figures indicates “prism for color combination”. There is. The image display element MD shown in the figure is representatively shown as "a liquid crystal panel for green image component", and the other two color image display elements are not shown.

As shown in the figures, the projection zoom lens has a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a positive lens power in order from the enlargement side to the reduction side. A third lens group G3 having a refractive power and a fourth lens group G4 having a positive refractive power are disposed, and an aperture stop S is fixedly disposed in the fourth lens group or on the enlargement side of the fourth lens group. .
The zoom lens for projection is substantially telecentric on the reduction side, and during zooming, the fourth lens group G4 and the aperture stop S are fixed, and the first lens group G1, the second lens group G2, and the third lens group G3 are in the optical axis direction To move independently.
Also, the F value is constant in the entire variable magnification range by zooming. “The F value is constant in the entire zoom range by zooming” includes not only the case where the F value is strictly constant in the entire zoom range but also the case where the F value is substantially constant.

As described above, the projection zoom lens according to the present invention is composed of four lens groups having “negative, positive, positive, positive refractive power” from the enlargement side. Since the fourth lens group G4 and the aperture stop S are "fixed", they do not move during zooming.
During zooming, the three lens units of the first to third lens units G1 to G3 move independently on the optical axis and are distributed to the optimum position, thereby achieving "good optical performance" over the entire zoom range. Is realized.
Since the aperture stop S and the fourth lens group G4 are fixed, the diameter of the light flux exiting the image display element MD and passing through the aperture stop S is always "constant". The fourth lens group G4 has a positive refracting power, so that the angle with respect to the optical axis of the "marginal ray going out from the aperture stop S toward the enlargement side" is gentle, and the first to third lens groups G3 can be zoomed. Even if it moves on the optical axis, "marginal light beam is not intercepted at all" and F value can be made constant regardless of zooming.
Further, the aperture stop S for determining the brightness of the projection zoom lens is fixedly disposed on the enlargement side of the fourth lens group G4 or the fourth lens group G4, and the chief ray passing through the center of the aperture stop S also zooms. Because no change occurs, good telecentricity is realized over the entire zoom range.
The movement of the first lens group G1 to the third lens group G3 during zooming from the wide-angle end to the telephoto end is "independent of each other" as described above, but the first lens during zooming from the wide-angle end to the telephoto end The group G1 moves from the enlargement side to the reduction side, and the second lens group G2 and the third lens group G3 can move from the reduction side to the enlargement side. This configuration is referred to as “configuration 2”.
In the projection zoom lens of the embodiment shown in each of the above-mentioned drawings, "movement of the first lens group G1 to the third lens group G3 in zooming from the wide-angle end to the telephoto end" becomes as described in the configuration 2. There is. Since the total lens length becomes longer at the wide-angle end, if the movements of the first to third lens groups G1 to G3 are the same as in the configuration 2, the "aberration correction at the wide-angle" becomes relatively easy.

In the case of configuration 2, the amount of movement of the first lens group G1 during zooming from the wide-angle end to the telephoto end: DP1G, and the amount of movement of the second lens group G2: DP2G,
(1) 0.1 <DP1G / DP2G <2.0
To be satisfied.

The projection zoom lens of configuration 1 or 2 may also have a back focus in air when the conjugate point on the enlargement side is at infinity: Bf, a focal length of the entire system at the wide-angle end: f _W , a focal length of the first lens group : F1 but the condition:
(2) 1.0 <Bf / f _W <2.7
(3) 1.7 <| f1 / f _W | <10.0
It is preferable to satisfy This configuration is referred to as “configuration 3”.
The condition (1) and the conditions (2) and (3) may be "satisfied" and only the conditions (2) and (3) may be satisfied.

  The projection zoom lens of the above configuration 1 or 2 or 3 is also a positive lens having a large curvature on the reduction side: LP and a negative lens having a large curvature on the enlargement side: LN in the first lens group G1. The lenses of the above are disposed in order from the enlargement side, and a “negative air lens having a large curvature on the reduction side” can be formed between the positive lens: LP and the negative lens: LN. This configuration is referred to as "configuration 4".

The magnitude of the “curvature” referred to in Configuration 4 above is “the magnitude of the absolute value of the curvature”.
In the projection zoom lens of Configuration 4, the negative lens in the first lens group G1: Abbe number of _LN :: _LN , and the partial dispersion ratio: θgF, the conditions:
(4) 0.01 <θgF-(0.6438-0.001682 _LN ) <0.05
It is preferable to satisfy The configuration of the projection zoom lens that satisfies the condition (4) is referred to as “configuration 5”.

In the projection zoom lens according to any one of the configurations 1 to 5, the second lens group G2 can be configured of one positive lens. This configuration is called "Configuration 6".
In the projection zoom lens of Configuration 6, the refractive index N _{2 G} with respect to the d-line of one positive lens forming the second lens group G2 is:
(5) 1.8 <N _{2 G}
Satisfy.

  In the projection zoom lens according to any one of the first to sixth aspects, the first lens group G1 is set to “1a sub lens group in order from the enlargement side to the reduction side, 1 b sub lens group having negative refractive power, positive refraction The 1c sub lens group moves on the optical axis from the enlargement side to the reduction side during focusing in which the 1c sub lens group having a force is disposed and the conjugate point on the enlargement side is moved from the long distance to the near direction. The distance between the lens unit and the 1b sub lens unit may be changed. This configuration is referred to as “configuration 7”.

The significance and the like of the conditions (1) to (5) listed above will be described below.
The parameter of the condition (1): DP1G / DP2G is “the ratio of the movement amount of the first lens group G1 to the movement amount of the second lens group G2” in the zooming from the wide angle end to the telephoto end. Here, the "movement amount" is an "absolute value of displacement" independent of the movement direction, and DP1G and DP2G are both positive numerical values.
Parameter: If DP1G / DP2G exceeds the upper limit of condition (1), the amount of movement of the first lens group G1 becomes large, and the “full length and lens outer diameter” at the wide-angle end become excessive, and the projection zoom lens becomes large easy.
In addition, when the parameter DP1G / DP2G exceeds the lower limit of the condition (1), the moving range of the first lens group G1 is limited, and the maintenance of high optical performance tends to be difficult.

  By satisfying the condition (1), it becomes easy to balance the “compactness and good optical performance” of the projection zoom lens.

Parameter condition (2): Bf / f _W is the focal length of the entire system at the wide angle end: the fraction of "back focus in air when the conjugate point of the expansion side of infinity" for f _W, parameters: When bf / _{f W} becomes larger (smaller), the focal length at the wide angle end: _{f W} is small or becomes (large), the back focus: bf may become large (small).

When the focal length: f _W becomes smaller, the refractive power of the entire system becomes large and “correction of various aberrations” becomes difficult, and when the back focus: Bf becomes smaller, the optical arrangement on the image display element side (the above-mentioned prism P Arrangement etc. is likely to be difficult. Also, when the focal length: f _W becomes large, the refractive power of the whole system becomes small and "projected image becomes small" easily, and when the back focus: Bf becomes too large, a projection type image display apparatus including a projection zoom lens It is easy to make
Parameters: Bf / f _W by a range of conditions (2), can be balanced optical performance and ease of optical arrangement of an image display device side of the projection zoom lens.

The parameter of the condition (3): | f1 / f _W | is a ratio of the focal length of the first lens group G1 to the focal length of the entire system at the wide-angle end: f _W : f1 as an absolute value. _| f1 / f W | the larger (smaller), the negative refractive power of the first lens group G1 is weak or becomes (stronger), the refractive power of the entire system may become stronger (weaker).

When the negative refractive power of the first lens group G1 weakens, the angle of view on the enlargement side decreases, and it becomes difficult to realize a wide angle of view as a projection zoom lens, and when the refractive power of the entire system becomes strong Correction is likely to be difficult.
When the negative refractive power of the first lens group G1 becomes strong, the angle of view on the enlargement side becomes large, but it tends to be difficult to keep good aberrations such as coma and field curvature. In addition, when the refractive power of the entire system becomes too small, “projected image is likely to be too small”.

In the range in which the condition (3) holds, “coexistence of wide angle of view and optical performance” is easy.
Therefore, by satisfying the conditions (2) and (3) in combination, the back focus, wide angle of view, and optical performance of the projection zoom lens can be easily balanced.

  In the projection zoom lens of Configuration 4, in the first lens group G1, a positive lens having a large curvature on the reduction side: LP and a negative lens having a large curvature on the enlargement side: LN from the enlargement side By arranging in order, an “air lens” with a large curvature on the reduction side is formed as a negative lens between positive lens: LP and negative lens: LN, making it easy to correct lateral chromatic aberration. .

  The condition (4) in the fifth configuration is a condition for the negative lens in the above-mentioned fifth configuration: material of the LN, and the negative lens: LN made of a material satisfying the condition (4) Can be small.

The partial dispersion ratio θgF under the condition (4) is defined as follows.
That is, when the refractive index of optical glass is “Ng for g line (435.83 nm), NF for F line (486.13 nm), NC for C line (656.27 nm), The dispersion ratio θgF is
θgF = (Ng-NF) / (NF-NC)
Defined by

By configuring the negative lens: LN with a material that satisfies Abbe's number: _LN and the partial dispersion ratio: θgF to the condition (4), the magnification chromatic aberration of the projection zoom lens can be “reduced”, and a wide angle of view can be obtained. It is possible to obtain a good image.

In the projection zoom lens of Configuration 6, the second lens group G2 is configured of one positive lens that satisfies the condition (5).
As in the sixth configuration, by including “a lens group configured of one lens” in the four lens groups, it is possible to realize a low-cost and compact projection zoom lens.

  When the angle of view of the projector is increased, if the projection distance is changed due to the change of the distance to the screen, it is not always easy to perform focusing while maintaining the "flatness of the image plane".

  In the projection zoom lens according to the seventh aspect, the first lens group G1 includes three sub lenses, i.e., from the enlargement side, the 1a sub lens group, the 1 b sub lens group having negative refractive power, and the 1 c sub lens group having positive refractive power. The 1c sub lens group moves on the optical axis from the enlargement side to the reduction side during focusing from a long distance to a short distance direction, and the distance between the 1 a sub lens group and the 1 b sub lens group By moving at least one of the 1a sub lens group and the 1 b sub lens group, it is possible to have a wide projection distance range while maintaining the flatness of the image plane.

Before describing a specific embodiment of the projection zoom lens, one embodiment of a projection type image display device will be described with reference to FIG.
FIG. 39 is a view for explaining a projector which is an example of the projection type image display device.
The “projector” indicated by reference numeral 10 is an apparatus for projecting “image information” given from a computer or the like (not shown) as a color enlarged projection image on the projection surface S.
Reference numeral 11 is a "controller", reference symbol LR is a "red light source", reference symbol LG is a "green light source", reference symbol LB is a "blue light source", and reference symbol MDR is a "liquid crystal panel for red component image", reference symbol MDG indicates a "liquid crystal panel for green component image", and a code MDB indicates a "liquid crystal panel for blue component image".
The code P indicates a prism for color synthesis. The prism P is a "cross prism using a dichroic film".
The symbol ZLN indicates a “projection zoom lens”. As the projection zoom lens ZLN, the projection zoom lenses of claims 1 to 7, for example, the projection zoom lenses of Examples 1 to 5 described later can be used.

The controller 11 is configured as a computer or a CPU, and controls the red light source LR, the green light source LG, the blinking of the blue light source LB, and the zoom mechanism and the focus mechanism of the projection zoom lens ZLN.
The controller 11 also controls the liquid crystal panels MDR, MDG, and MDB in accordance with “image information” given from the outside, and displays a red component image, a green component image, and a blue component image on these.
The red component image displayed on the liquid crystal panel MDR is irradiated with red light from the red light source LR, and the red light transmitted through the liquid crystal panel MDR is intensity-modulated by the red component image to become "red image light". Incident on P
The green component image displayed on the liquid crystal panel MDG is irradiated with green light from the green light source LG, and the green light transmitted through the liquid crystal panel MDG is intensity-modulated by the green component image to become "green image light". Incident on P
The blue component image displayed on the liquid crystal panel MDB is irradiated with blue light from the blue light source LB, and the blue light transmitted through the liquid crystal panel MDB is intensity-modulated by the blue component image to become "blue image light". Incident on P
The prism P combines the incident red image light, the green image light, and the blue image light into “one light flux”, and causes the light to enter the projection zoom lens ZLN as color image light.
The color image light enlarges and projects the “color image by image information” on the screen S which is a projection surface by the projection zoom lens ZNL.

Hereinafter, five specific examples of the projection zoom lens will be described.
As described above, Examples 1 to 5, which are the examples of these five examples, are specific numerical examples of the embodiment shown in FIG. 1, FIG. 8, FIG. 15, FIG. .
In all of the first to fifth embodiments, the projection zoom lens includes, in order from the enlargement side to the reduction side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive lens group. A third lens group G3 having a refractive power of and a fourth lens group G4 having a positive refractive power are disposed.

In any of the embodiments, the first lens group G1 is, as shown in the drawing at the telephoto end, 1a sub lens group, 1 b sub lens group, 1 c sub lens group (respectively 1a, 1b, 1c) , And is hereinafter referred to as sub lens group 1a, sub lens group 1b, and sub lens group 1c).
The sub lens group 1b has two lenses of a positive lens LP having a large curvature on the reduction side and a negative lens LN having a large curvature on the enlargement side, and “the reduction” is performed between the positive lens LP and the negative lens LN. It forms a negative air lens with large curvature on the side.
Further, the sub lens group 1c is configured by "one positive lens".

  In each of the drawings showing Example 1 to Example 5, the projection distance (the distance on the optical axis between the lens surface on the most enlargement side of the projection zoom lens and the screen being the projection surface) at both the wide-angle end and the telephoto end 6 shows a state in which the distance between the sub lens units 1a to 1c is adjusted so as to focus on 2700 mm.

In the data notation of each example, “surface number” refers to the lens surface of each lens constituting the projection zoom lens, the aperture stop S, and the surface of the prism P from the enlargement side (screen side) to the reduction side (image display element The screen is represented by an "object plane", and the image display surface of an image display element (a liquid crystal panel is assumed) is represented as an "image plane".
“R” represents the radius of curvature (paraxial radius of curvature in the case of an aspheric surface) of each surface (including the surface of the aperture stop S, the prism P for color synthesis, and the surface of the cover glass CG), “D” Represents the surface separation on the optical axis.
"Nd" and "vd" indicate the "refractive index and Abbe number for d-line" of the material of each lens. “Image height” is the maximum height of the image display surface from the optical axis, “BF” is the lens surface on the most reduction side in the air (with no prism or cover glass) when the conjugate point on the enlargement side is infinity The distance to the paraxial image (back focus) is represented, and "total lens length" is represented by the distance from the lens surface on the most enlargement side to the lens surface on the most reduction side.
The unit of quantity with dimension of length is "mm" unless otherwise stated.

The zoom lens for projection in the following examples includes an aspheric lens, but the “aspheric shape” has an intersection point of the optical axis and the aspheric surface as an origin, and a height relative to the optical axis: h, displacement in the optical axis direction : Z, paraxial radius of curvature: R, conic constant: K, nth order aspheric coefficient: An, well known equation:
Z = (1 / R) · h ² / [1 + {{1-(1 + K) · (1 / R) ² · h ² }]
+ A 4 · h ⁴ + A 6 · h ⁶ + A 8 · h ⁸ + ... + An · h ⁿ
The above R, K, An are given to specify the shape. In addition, the surface which employ | adopted the aspherical surface attaches and shows "* mark" to surface number.

"Example 1"
Example 1 shows lens configurations at the wide-angle end (upper figure) and the telephoto end (lower figure) in FIG.

Each of the first lens group G1, the second lens group G2 and the fourth lens group G4 is composed of a plurality of lenses, and the third lens group G3 has one positive meniscus lens (a convex surface is directed to the enlargement side). It consists of).
The aperture stop S is fixedly provided in proximity to the “magnification side surface” of the lens on the most enlargement side in the fourth lens group G4.
The data of Example 1 in the case of 2700 mm of projection distances are shown below.
"Lens data"
Face number R D Nd d d
Object surface 270 270.000
1 114.618 3.500 1.48749 70.44
2 54.709 4.074
3 60.770 17.000 1.92286 20.88
4 102.279 5.000
5 111.779 2.750 1.49700 81.61
6 39.599 13.028
7 * 148.678 2.200 1.49710 81.56
8 * 41.011 11.593
9-196.388 2.000 1.49700 81.61
10 81.610 22.928
11-93.776 10.997 2.00100 29.13
12 -60.028 1.567
13-51.963 6.963 1.92286 20.88
14 -95.916 1.030
15 414.322 10.553 1.49700 81.61
16 -69.792 (variable)
17 80.858 3.000 1.85478 24.80
18 40.491 0.200
19 40.631 8.288 1.80610 33.27
20 124.218 (variable)
21 145.482 4.159 1.49700 81.61
22 1434.729 (variable)
23 (F-stop) ∞ 0.586
24-209.853 3.000 1.49700 81.61
25 -111.085 13.272
26 -38.171 2.000 1.70154 41.15
27 114.986 2.309
28 * 59.121 9.929 1.49710 81.56
29 * -39.140 0.200
30 103.020 2.000 1.72342 37.99
31 47.443 2 .264
32 86.362 12.522 1.49700 81.61
33-30.834 0.200
34-31.066 1.300 1.85026 32.27
35 237.978 0.500
36 287.469 8.663 1.92286 20.88
37-55. 202 0.200
38 107.474 8.068 1.49700 81.61
39 -109.500 11.000
40 ∞ 52.000 1.51680 64.17
41 ∞ 5.700
42 3. 3.000 1.48640 65.40
43 0.3 0.300
Image plane ∞.
"Aspheric surface data"
The aspheric surface data are shown below.
"Seventh"
K = 14.487449,
A4 = -3.942359 x 10 ^-7 ,
A6 = -1.825420 × 10 ^-9 ,
A8 = 1.319733 × 10 ⁻¹² ,
A10 = −4.961563 × 10 ⁻¹⁶ ,
A12 = -9.173501 10 ^-20
"Eighth"
K = 1.804924 × 10 ⁻¹ ,
A4 = -1.853522 x 10 ^-6 ,
A6 = -2.994599 x 10 ^-9 ,
A8 = 5.834780 × 10 ⁻¹³ ,
A10 = 1.544799 × 10 ⁻¹⁶ ,
A12 = -6.299101 x 10 ^-19
"The 28th"
K = -2.585589,
A4 = -7.187182 × 10 ^-8 ,
A6 = 1.148045 × 10 ⁻⁹ ,
A8 = -4.755433 × 10 ⁻¹² ,
A10 = 1.928669 × 10 ^-14 ,
A12 =-2.895 439 x 10 ^-17
"The 29th"
K = 1.593398,
A4 = 4.389851 × 10 ⁻⁶ ,
A6 = 4.345218 × 10 ⁻⁹ ,
A8 = 4.293337 × 10 ⁻¹² ,
A10 = 9.280262 x 10 ^-15 ,
A12 = 1.567078 × 10 ^-17.

"Variable interval"
In the lens data shown above, the surface distance displayed as “variable” is “variable distance”, and the values of the variable distance at each zoom position at the wide-angle end, intermediate focal length (displayed as middle) and telephoto end are Show.
Zoom position Wide-angle end Middle Telephoto end
D16 60.562 30.495 4.651
D20 2.000 6.307 8.135
D22 9.593 16.693 24.193.

"Various data"
Various data at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end
Focal length 25.316 27.823 30.328
F value 2.0 2.0 2.0
Half angle of view 32.63 ° 30.29 ° 28.21 °
Image height 16.000 16.000 16.000
BF 53.300 53.300 53.300
Lens total length 270.000 251.341 234.823.

"Value of parameter of each conditional expression"
The values of the parameters of the conditions (1) to (4) are shown below.
(1) DP1G / DP2G = 1.697
(2) Bf / f _W = 2.105
(3) | f1 / f _W | = 8.267
(4) θgF-(0.6438-0.001682 v _LN ) = 0.0282.

A diagram of spherical aberration, astigmatism and distortion at the “wide-angle end” of the projection zoom lens of Example 1 is shown in FIG. 2, and a diagram of coma is shown in FIG. Each aberration diagram shows the aberration of green light having a wavelength of 545 nm, but the spherical aberration diagram and the coma aberration diagram also show the aberrations of wavelength: 635 nm and 460 nm, representing red and blue lights. In the astigmatism diagram, S indicates a sagittal image, and M indicates an aberration of a meridional image.
The diagram of spherical aberration, astigmatism and distortion at “intermediate focal length” is shown in FIG. 4, the diagram of coma at FIG. 5 and the diagram of spherical aberration, astigmatism and distortion at “telephoto end” The figure of coma is shown in FIG.

  The data shown above is for the projection distance of 2700 mm as described above, but FIG. 36 shows the state of focusing from the projection distance of 2700 mm to the projection distance of 1550 mm at the wide-angle end. As shown in the figure, in focusing to a projection distance of 1550 mm, the 1c sub lens group 1c moves on the optical axis from the enlargement side to the reduction side, and the sub lens group 1b also moves independently from the enlargement side to the reduction side. The distance to the lens unit 1a is changed.

  The distance between the sub lens units 1a, 1b and 1c (surface distance: D4 and D14) when the projection zoom lens of Example 1 is focused to a projection distance of 1550 mm, the sub lens unit 1c and the second lens unit G2 The spacing between the faces (surface spacing: D16) is shown below.

Projection distance: 1550 mm
D4 5.976
D14 1.550
D16 59.066.

  FIG. 37 shows a diagram of spherical aberration, astigmatism and distortion at a projection distance of 1550 mm at the wide-angle end in Example 1, and FIG. 38 shows a diagram of coma.

"Example 2"
Example 2 shows lens configurations at the wide-angle end (upper figure) and the telephoto end (lower figure) in FIG.
The projection zoom lens of Example 2 is an example in which the second lens group G2 is configured of “one positive lens”. Each of the first lens group G1, the third lens group G3 and the fourth lens group G4 is composed of a plurality of lenses, and the aperture stop S is a surface on the "magnification side" of the most enlargement side lens in the fourth lens group G4. Fixed in proximity to the

The data of Example 2 in the case of 2700 mm of projection distances are shown below.
"Lens data"
Face number R D Nd d d
Object surface 270 270.000
1 106.475 15.200 2.00100 29.13
2 220.727 0.301
3 124.860 2.750 1.49700 81.61
4 39.850 14.797
5 * 307.585 2.400 1.49710 81.56
6 * 43.995 18.953
7-56.784 2.000 1.75211 25.05
8 124.361 5.460
9 -227.051 7.001 1.92286 20.88
10 -67.272 4.686
11 -44.259 2.000 1.92286 20.88
12 -68.008 1.143
13 -71.087 7.457 1.49700 81.61
14-45. 906 (variable)
15 250.192 7.437 2.00100 29.13
16-169.442 (variable)
17 197.701 9.413 1.49700 81.61
18-45.054 0.200
19 -44.446 2.000 1.55298 55.07
20 -77.077 (variable)
21 (F-stop) 767 2.767
22 -95.565 2.000 1.67270 32.17
23 255.948 3.181
24-52.160 3.622 1.75367 37.50
25-98. 918 6. 104
26 * 102.081 5.544 1.49710 81.56
27 * -74.376 3.737
28 80.121 5.447 1.69895 30.05
29 56.062 1.626
30 103.243 11.158 1.49700 81.61
31-28.331 0.215
32-27.966 1.300 1.78470 26.29
33 92.968 0.500
34 100.437 16.000 1.92286 20.88
35 -60.534 2.251
36 59.052 11.000 1.49700 81.61
37 358.459 11.000
38 ∞ 32.000 1.51680 64.17
39 ∞ 5.700
40 3. 3.000 1.48640 65.40
41 ∞ 0.300
Image plane ∞.

"Aspheric surface data"
The aspheric surface data are shown below.
"Fifth"
K = 61.859984,
A4 = 1.798782 × 10 ⁻⁶ ,
A6 = -1.185521 × 10 ⁻⁹ ,
A8 = 9.774983 x 10 ^-13 ,
A10 = −3.965492 × 10 ⁻¹⁶ ,
A12 = 1.446459 x 10 ^-19
"Sixth"
K = 7.329964 × 10 ⁻¹ ,
A4 = -8.599894 × 10 ^-8 ,
A6 = -2.502768 x 10 ^-9 ,
A8 = 1.943432 × 10 ⁻¹² ,
A10 = −2.455757 × 10 ⁻¹⁵ ,
A12 = 9.117421 x 10 ^-19
"The 26th"
K = 1 1.758452,
A4 = -3.911935 × 10 ^-7 ,
A6 = 1.636185 × 10 ⁻⁹ ,
A8 = −1.203025 × 10 ⁻¹¹ ,
A10 = 4.108715 × 10 ^-14 ,
A12 = −4.538341 × 10 ⁻¹⁷
"The 27th"
K = 3.356161,
A4 = 1.992653 × 10 ^-6 ,
A6 = 2.513 905 × 10 ^-9 ,
A8 = −9.939873 × 10 ⁻¹² ,
A10 = 3.180958 × 10 ^-14 ,
A12 = −2.551441 × 10 ⁻¹⁷ .

"Variable interval"
Values of variable intervals at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end D14 13.01 6.263 1.000
D16 72.834 68.546 64.341
D20 1.500 11.231 20.434.

"Various data"
Various data at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Intermediate telephoto end Focal length 25.235 27.767 30.303
F number 2.0 2.0 2.0
Half angle of view 32.55 ° 30.03 ° 27.80 °
Image height 16.000 16.000 16.000
BF 40.114 40.114 40.114
Total lens length 270.000 268.690 268.424.

"Value of parameter of each conditional expression"
The values of the parameters of the conditions (1) to (5) are shown below.
(1) DP1G / DP2G = 0.151
(2) Bf / f _W = 1.590
(3) | f1 / f _W | = 1.864
(4) θgF-(0.6438-0.001682 v _LN ) = 0.0282
(5) N _{2 G} = 2.00100.

  A diagram of spherical aberration, astigmatism and distortion at the wide angle end of the projection zoom lens of Example 2 is shown in FIG. 9, and a diagram of coma is shown in FIG. Also, the diagrams of spherical aberration, astigmatism and distortion at the intermediate focal length are shown in FIG. 11, those of coma are shown in FIG. 12, and those of spherical aberration, astigmatism and distortion at the telephoto end are shown in FIG. A diagram of coma is shown in FIG.

"Example 3"
The third embodiment shows a lens configuration at the wide-angle end and the telephoto end in FIG.
The first lens group G1, the second lens group G2, and the fourth lens group G4 are each composed of a plurality of lenses, and the third lens group G3 is composed of a single biconvex lens (having a large curvature on the reduction side). ing.
The aperture stop S is fixedly provided in proximity to the “magnification side surface” of the lens on the most enlargement side in the fourth lens group G4.
The data of Example 3 in the case of 2700 mm of projection distances are shown below.
"Lens data"
Face number R D Nd d d
Object surface 270 270.000
1 111.988 21.000 1.80100 34.97
2 353.405 0.300
3 108.551 3.500 1.51742 52.15
4 43.816 20.341
5 1162.620 2.750 1.49700 81.61
6 109.151 4.616
7 *-418.057 2.200 1.49710 81.56
8 * 53.539 15.607
9-60.127 2.000 1.64769 33.84
10 124.336 4.892
11-295.755 7.729 2.00100 29.13
12 -63.180 5.069
13 -41.292 2.000 1.85896 22.73
14 -108.948 1.114
15-113.795 11.000 1.49700 81.61
16-45.584 (variable)
17 203.171 3.000 1.74950 35.33
18 111.286 1.094
19 135.399 9.000 2.00100 29.13
20 -196.122 (variable)
21 233.997 12.000 1.49700 81.61
22 -98.771 (variable)
23 (F-stop) 0.2 0.228
24 -719.282 2.481 1.68893 31.16
25 265.551 17.265
26-42.036 2.000 1.90366 31.32
27 -99.248 0.200
28 * 2101.383 5.878 1.49710 81.56
29 * -45.695 0.200
30 119.627 2.000 1.90366 31.32
31 76.104 1.288
32 141.988 11.444 1.49700 81.61
33-28.319 0.200
34-28.050 4.492 1.80000 29.84
35 103.923 0.500
36 116.494 12.024 1.92119 23.96
37-59. 588 0.200
38 65.633 9.678 1.49700 81.61
39-182.804 11.000
40 ∞ 42.000 1.51680 64.17
41 ∞ 5.700
42 3. 3.000 1.48640 65.40
43 0.3 0.300
Image plane ∞.

"Aspheric surface data"
The aspheric surface data are shown below.
"Seventh"
K = -37.152181,
A4 = 2.035364 x 10 ^-6 ,
A6 = -1.486835 × 10 ^-9 ,
A8 = 1.184204 × 10 ⁻¹² ,
A10 = -1.673910 × 10 ^-16 ,
A12 = 2.125291 × 10 ^-21
"Eighth"
K = 1.093743,
A4 = 4.746222 × 10 ⁻⁹ ,
A6 = −2.039794 × 10 ⁻⁹ ,
A8 = 1.102163 × 10 ⁻¹² ,
A10 = −7.473956 × 10 ⁻¹⁶ ,
A12 = 7.969077 × 10 ^-19
"The 28th"
K = 99.000000,
A4 = 5.695715 × 10 ^-7 ,
A6 = 4.119019 × 10 ^-9 ,
A8 = -1.012245 × 10 ⁻¹¹ ,
A10 = 4.685321 x 10 ^-14 ,
A12 = −2.976678 × 10 ⁻¹⁷
"The 29th"
K = 1.838004,
A4 = 2.959810E-06 x 10 ^-6 ,
A6 = 4.783293E-09 × 10 ^-9 ,
A8 =-2.233 030 E-12 x 10 ^-12 ,
A10 = 1.660811E-14 × 10 ^-14 ,
A12 = 3.195174 E-17 x 10 ^-17 .

"Variable interval"
Values of variable intervals at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end D16 14.092 6.740 1.000
D20 75.121 69.569 64.273
D22 1.500 12.192 22.220.

"Various data"
Various data at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end
Focal length 25.403 27.950 30.503
F number 2.0 2.0 2.0
Half angle of view 32.32 ° 29.86 ° 27.67 °
Image height 16.000 16.000 16.000
BF 46.707 46.707 46.707
Lens total length 290.000 287.789 286.781.

"Value of parameter of each conditional expression"
The values of the parameters of the conditions (1) to (4) are shown below.
(1) DP1G / DP2G = 0.326
(2) Bf / f _W = 1.839
(3) | f1 / f _W | = 1.951
_{(4) θgF- (0.6438-0.001682ν LN)} = 0.0237.

  A diagram of spherical aberration, astigmatism and distortion at the wide-angle end of the projection zoom lens of Example 3 is shown in FIG. 16 and a diagram of coma is shown in FIG. Figures of spherical aberration, astigmatism and distortion at the intermediate focal length are shown in Figure 18; figures of coma are shown in Figure 19; figures of spherical aberration, astigmatism and distortion at the telephoto end are shown in Figure 20; coma Is shown in FIG.

"Example 4"
The fourth embodiment shows a lens configuration at the wide-angle end and the telephoto end in FIG.

The first lens group G1, the second lens group G2, and the fourth lens group G4 are each composed of a plurality of lenses, and the third lens group G3 is composed of a single biconvex lens (having a large curvature on the reduction side). ing.
The aperture stop S is fixedly provided in proximity to the “magnification side surface” of the lens on the most enlargement side in the fourth lens group G4.
The data of Example 4 in the case of 2700 mm of projection distances are shown below.
"Lens data"
Face number R D Nd d d
Object surface 270 270.000
1 106.633 21.000 1.72342 37.99
2 427.284 0.300
3 170.178 3.500 1.48749 70.44
4 47.235 19.803
5 537.432 2.750 1.48749 70.44
6 64.471 5.466
7 * 286.531 2.200 1.49710 81.56
8 * 54.437 16.423
9 -60.774 2.000 1.56732 42.84
10 128.100 5.396
11 -248.768 7.235 2.00100 29.13
12 -68.141 5.369
13 -43.185 2.000 1.92286 20.88
14 -98.449 1.132
15 -103.303 10.883 1.49700 81.61
16 -46.284 (variable)
17 217.309 2.500 1.74950 35.33
18 127.562 1.348
19 167.365 9.000 2.00100 29.13
20 -178.035 (variable)
21 212.483 5.705 1.49700 81.61
22 -101.832 (variable)
23 (F-stop) ∞ 0.748
24 -152.981 2.000 1.74950 35.33
25 313.017 16.926
26 -39.736 2.285 1.95375 32.32
27 -66.341 1.733
28 * 614.135 6.380 1.51633 64.07
29 *-46.622 0.200
30 99.655 2.000 1.95000 29.37
31 62.036 1.218
32 91.701 11.953 1.49700 81.61
33-31.060 0.230
34-30.915 1.300 1.80000 29.84
35 116.551 0.500
36 132.765 11.422 1.92286 20.88
37 -76.908 1.117
38 82.897 9.617 1.49700 81.61
39 -101.970 11.000
40 ∞ 52.000 1.51680 64.17
41 ∞ 5.700
42 3. 3.000 1.48640 65.40
43 0.3 0.300
Image plane ∞.

"Aspheric surface data"
The aspheric surface data are shown below.
"Seventh"
K = 56.901336,
A4 = 1.824234 × 10 ⁻⁶ ,
A6 = -1.545069 x 10 ^-9 ,
A8 = 1.165322 × 10 ⁻¹² ,
A10 = −4.247046 × 10 ⁻¹⁷ ,
A12 = -1.260937 × 10 ^-19
"Eighth"
K = 1.121687,
A4 = 8.824482 × 10 ⁻⁸ ,
A6 = -2.344765 x 10 ^-9 ,
A8 = 1.563168 × 10 ⁻¹² ,
A10 = −4.784365 × 10 ⁻¹⁶ ,
A12 = 1.802333 × 10 ⁻¹⁹
"The 28th"
K = 64.173010,
A4 = 3.161508 ^10-7 ,
A6 = 2.635179 × 10 ⁻⁹ ,
A8 = -9.254100 × 10 ⁻¹² ,
A10 = 2.780843 × 10 ^-14 ,
A12 =-1947 356 × 10 ⁻¹⁷
"The 29th"
K = 1.850683,
A4 = 2.683265 × 10 ^-6 ,
A6 = 3.895499 x 10 ^-9 ,
A8 = -2.669465 x ^10-12 ,
A10 = 1.066311 × 10 ^-14 ,
A12 = 1.172932 × 10 ⁻¹⁷ .

"Variable interval"
Values of variable intervals at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end D16 14.660 6.981 1.000
D20 80.200 74.367 68.942
D22 1.500 12.004 21.829.

"Various data"
Various data at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end focal length 25.388 27.931 30.478
F number 2.0 2.0 2.0
Half angle of view 32.34 ° 29.87 ° 27.68 °
Image height 16.000 16.000 16.000
BF 53.300 53.300 53.300
Total lens length 290.000 286.992 285.411.

"Value of parameter of each conditional expression"
The values of the parameters of the conditions (1) to (4) are shown below.
(1) DP1G / DP2G = 0.506
(2) Bf / f _W = 2.099
(3) | f1 / f _W | = 1.950
(4) θgF-(0.6438-0.001682 v _LN ) = 0.0282.

  FIG. 23 shows a diagram of spherical aberration, astigmatism and distortion at the wide-angle end of the projection zoom lens of Example 4, and FIG. 24 shows a diagram of coma. The diagrams of spherical aberration, astigmatism and distortion at the intermediate focal length are shown in FIG. 25, the diagrams of coma are shown in FIG. 26, the diagrams of spherical aberration, astigmatism and distortion at the telephoto end are shown in FIG. Is shown in FIG.

"Example 5"
The fifth embodiment shows a lens arrangement at the wide-angle end and the telephoto end in FIG.

The first lens group G1, the second lens group G2, and the fourth lens group G4 are each composed of a plurality of lenses, and the third lens group G3 is composed of a single biconvex lens (having a large curvature on the reduction side). ing.
The aperture stop S is fixedly provided in proximity to the “reduction side surface” of the most enlargement side lens in the fourth lens group G4. That is, in the fifth embodiment, the aperture stop S is provided in the fifth lens group G5.
The data of Example 5 in the case of 2700 mm of projection distances are shown below.
"Lens data"
Face number R D Nd d d
Object surface 270 270.000
1 111.334 18.000 1.80610 33.27
2 441.176 0.300
3 249.515 3.500 1.48749 70.44
4 44.028 20.661
5-9238.189 2.750 1.51680 64.20
6 106.798 2.000
7 * 391.367 2.200 1.49710 81.56
8 * 57.122 17.111
9 -64.048 2.000 1.57501 41.51
10 114.698 4.356
11 2339.226 8.644 2.00100 29.13
12 -80.888 5.93
13 -46.980 2.000 1.92286 20.88
14 -123.591 1.102
15-124.621 110.98 1.49700 81.61
16-50. 435 (variable)
17 416.080 2.500 1.70154 41.15
18 174.850 0.631
19 201.499 9.000 2.00330 28.27
20-170.065 (variable)
21 167.462 5.975 1.48749 70.44
22 -111.663 (variable)
23 -105.269 2.000 1.80610 33.27
24 3212.681 0.332
25 (F-stop) ∞ 20.192
26-52.062 2.000 1.95000 29.37
27 -123.972 0.222
28 * 165.408 5.658 1.51633 64.07
29 * -58.736 0.200
30 114.999 2.000 1.95000 29.37
31 63.467 1.502
32 122.330 11.308 1.49700 81.61
33-27.726 0.200
34-27.905 1.632 1.80610 33.27
35 138.481 0.500
36 164.685 10.647 1.92119 23.96
37-56.828 0.351
38 73.781 9.065 1.49700 81.61
39 -135.234 11.000
40 ∞ 62.001 1.51680 64.17
41 ∞ 5.700
42 3. 3.000 1.48640 65.40
43 0.3 0.300
Image plane ∞.

"Aspheric surface data"
The aspheric surface data are shown below.
"Seventh"
K = 99,
A4 = 1.858978 × 10 ^-6 ,
A6 = -1.427975 × 10 ^-9 ,
A8 = 9.626988 × 10 ⁻¹³ ,
A10 = −9.565907 × 10 ⁻¹⁷ ,
A12 = 1.547740 × 10 ^-20
"Eighth"
K = 1.129596,
A4 = 4.985104 × 10 ^-8 ,
A6 = -2.351118 × 10 ^-9 ,
A8 = 1.660536 × 10 ⁻¹² ,
A10 = -1.020311 × 10 ^-15 ,
A12 = 5.282089 x 10 ^-19
"The 28th"
K = 34.101408,
A4 = 3.085869 × 10 ^-7 ,
A6 = 3.454313 × 10 ⁻⁹ ,
A8 = -8.006743 × 10 ^-12 ,
A10 = 3.516745 × 10 ^-14 ,
A12 = -1.723407 × 10 ^-17
"The 29th"
K = 1.869507,
A4 = 2.435073 x 10 ^-6 ,
A6 = 4.272971 x 10 ^-9 ,
A8 = −3.191354 × 10 ⁻¹² ,
A10 = 1.795321 x 10 ^-14 ,
A12 = 2.750137 × 10 ⁻¹⁷ .

"Variable interval"
Values of variable intervals at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Middle Telephoto end D16 15.222 7.189 1.000
D20 85.801 78.561 72.085
D22 1.500 12.108 21.918.

"Various data"
Various data at each zoom position at the wide-angle end, at the middle, and at the telephoto end are shown below.
Zoom position Wide-angle end Intermediate telephoto end Focal length 25.336 27.873 30.413
F number 2.0 2.0 2.0
Half angle of view 32.42 ° 29.93 ° 27.72 °
Image height 16.000 16.000 16.000
BF 59.893 59.893 59.893
Total lens length 290.000 285.335 282.480.

"Value of parameter of each conditional expression"
The values of the parameters of the conditions (1) to (4) are shown below.
(1) DP1G / DP2G = 1.122
(2) Bf / f _W = 2.364
(3) | f1 / f _W | = 2.051
(4) θgF-(0.6438-0.001682 v _LN ) = 0.0282.

  A diagram of spherical aberration, astigmatism and distortion at the wide angle end of the projection zoom lens of Example 5 is shown in FIG. 30, and a diagram of coma is shown in FIG. The diagrams of spherical aberration, astigmatism and distortion at the intermediate focal length are shown in FIG. 32, the diagrams of coma are shown in FIG. 33, the diagrams of spherical aberration, astigmatism and distortion at the telephoto end are shown in FIG. Is shown in FIG.

In each embodiment, each aberration is well corrected at the wide-angle end, the intermediate focal length, and the telephoto end, and has high performance.
As described above, according to the present invention, the following projection zoom lens and projection type image display apparatus can be realized.
[1]
In order from the enlargement side to the reduction side, a first lens group (G1) having negative refractive power, a second lens group (G2) having positive refractive power, and a third lens group (G3) having positive refractive power And a fourth lens group (G4) having positive refractive power, and an aperture stop (S) is fixedly disposed on the enlargement side of the fourth lens group or in the fourth lens group, and the reduction side is substantially It is telecentric, and the fourth lens group (G4) and the aperture stop (S) are fixed during zooming, and the first lens group (G1), the second lens group (G2), and the third lens group (G3) are light. A projection zoom lens that moves independently in the axial direction and has a constant F value in the entire variable magnification range by zooming (Examples 1 to 5).

[2]
[1] The projection zoom lens according to [1], wherein the first lens group (G1) moves from the enlargement side to the reduction side during zooming from the wide-angle end to the telephoto end, and the second lens group (G2), the first The third lens group (G3) moves from the reduction side to the enlargement side, and the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end: DP1G, and the amount of movement of the second lens group: DP2G,
(1) 0.1 <DP1G / DP2G <2.0
Projection zoom lens that satisfies the above (Examples 1 to 5).

[3]
The zoom lens for projection according to [1] or [2], wherein the back focus in air when the conjugate point on the enlargement side is at infinity: Bf, the focal length of the entire system at the wide-angle end: f _W , first Lens unit focal length: f1, condition:
(2) 1.0 <Bf / f _W <2.7
(3) 1.7 <| f1 / f _W | <10.0
Projection zoom lens that satisfies the above (Examples 1 to 5).

[4]
The projection zoom lens according to any one of [1] to [3], wherein the first lens group is a positive lens having a large curvature on the reduction side: LP, and a negative lens having a large curvature on the enlargement side Lenses: Two lenses of LN are arranged in order from the enlargement side, and for projection, a negative air lens with a large curvature on the reduction side is formed between the positive lens: LP and the negative lens: LN Zoom lens (Examples 1 to 5).

[5]
[4] The projection zoom lens according to [4], wherein the negative lens in the first lens group (G1): Abbe number of LN: LN _LN , partial dispersion ratio: θgF, the conditions:
(4) 0.01 <θgF-(0.6438-0.001682 _LN ) <0.05
Projection zoom lens that satisfies the above (Examples 1 to 5).

[6]
In the zoom lens for projection according to any one of [1] to [5], the second lens group (G2) is composed of a single positive lens, and the refractive index of the positive lens to the d-line: N _2G, but conditions:
(5) 1.8 <N _{2 G}
Projection zoom lens that satisfies the above (Example 2).

[7]
The zoom lens for projection according to any one of [1] to [6], wherein the first lens group is composed of, in order from the enlargement side to the reduction side, 1a sub lens group, and 1b having a negative refractive power. The sub lens group includes a 1 c sub lens group having a positive refractive power, and the 1 c sub lens group has an enlargement on the optical axis during focusing for moving a conjugate point on the enlargement side from a long distance to a short distance direction. The projection zoom lens in which the distance between the 1a sub lens group and the 1 b sub lens group changes while moving from the lens to the reduction side (Examples 1 to 5).

[8]
The projection type image display apparatus (FIG. 39) which mounts the zoom lens for projection in any one of [1] thru | or [7].

  In each of the first to fourth embodiments, the first to fourth lens units each include “a lens unit configured with only one lens (third embodiment in the third and fifth embodiments, third embodiment G3 and second embodiment The second lens group G2) is included, and as described above, a low-cost and compact zoom lens for projection is realized.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above, and the invention described in the appended claims unless otherwise limited in the above description. Various modifications and changes are possible within the scope of the present invention.
The effects described in the embodiments of the present invention merely list the preferable effects resulting from the invention, and the effects of the invention are not limited to those described in the embodiments.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture stop
P Prism CG Cover Glass MD Image Display Element

Patent No. 4864600 Patent No. 5596500 gazette Patent No. 5302123

Claims (8)

A first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, and a third lens having positive refractive power in order from the enlargement side to the reduction side The fourth lens group is disposed, and an aperture stop is fixedly disposed on the fourth lens group or on the enlargement side of the fourth lens group, and the reduction side is substantially telecentric,
During zooming, the fourth lens group and the aperture stop are fixed, and the first lens group, the second lens group, and the third lens group move independently in the optical axis direction, and the F number in the entire zoom range by the zooming Projection zoom lens with constant. The projection zoom lens according to claim 1,
During zooming from the wide-angle end to the telephoto end, the first lens group moves from the enlargement side to the reduction side, and the second lens group and the third lens group move from the reduction side to the enlargement side, and from the wide-angle end to the telephoto end The amount of movement of the first lens group during zooming to the point: DP1G, the amount of movement of the second lens group: DP2G, the conditions:
(1) 0.1 <DP1G / DP2G <2.0
Projection zoom lens that satisfies the requirements. The projection zoom lens according to claim 1 or 2,
Back focus in air when the conjugate point on the magnification side is at infinity: Bf, focal length of the entire system at the wide-angle end: f _W , focal length of the first lens group: f1, the conditions:
(2) 1.0 <Bf / f _W <2.7
(3) 1.7 <| f1 / f _W | <10.0
Projection zoom lens that satisfies the requirements. The projection zoom lens according to any one of claims 1 to 3, wherein
In the first lens group, a positive lens having a large curvature on the reduction side: LP and a negative lens having a large curvature on the enlargement side: two lenses of LN are sequentially disposed from the enlargement side, and the positive lens: LP And the negative lens: A projection zoom lens in which a negative air lens having a large curvature on the reduction side is formed between LN. 5. The projection zoom lens according to claim 4, wherein
Negative lens in the first lens group: Abbe number of _LN :: _LN , partial dispersion ratio: θgF, conditions:
(4) 0.01 <θgF-(0.6438-0.001682 _LN ) <0.05
Projection zoom lens that satisfies the requirements. The projection zoom lens according to any one of claims 1 to 5, wherein
The second lens group is composed of a single positive lens, and the refractive index of the positive lens with respect to d-line: N _{2 G} , _satisfies the condition:
(5) 1.8 <N _{2 G}
Projection zoom lens that satisfies the requirements. The projection zoom lens according to any one of claims 1 to 6, wherein
The first lens group includes, in order from the enlargement side to the reduction side, the 1a sub lens group, the 1 b sub lens group having negative refractive power, and the 1 c sub lens group having positive refractive power. The 1c sub lens unit moves on the optical axis from the enlargement side to the reduction side during focusing to move the conjugate point of the lens from the far distance to the near distance direction, and the distance between the 1 a sub lens group and the 1 b sub lens group is Changing zoom lens for projection.   The projection type image display apparatus carrying the zoom lens for projection in any one of Claims 1-7.

Images