JP2018063308A - Zoom lens for projection and projection type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a new zoom lens for projection consisting of a seven lenz group.SOLUTION: A zoom lens for projection includes a seventh lens group 7G having, from an enlargement side to a reduction side, a first lens group 1G of a negative refractive power, a second lens group 2G of a positive refractive power, a third lens group 3G of the negative refractive power, a fourth lens group 4G of the positive refractive power, a fifth lens group 5G of the positive refractive power, a sixth lens group 6G of the negative or positive refractive power, and a seventh lens group having the positive refractive power, and comprises an aperture stop S between the fourth lens group 4G and the fifth lens group 5G. When zooming, a group interval from the first lens group 1G to the seventh lens group 7G is changed by a movement of the second lens group 2G to the seventh lens group 7G on an optical axis, and thus, a focal length: fw of the entire system at a wide angle end, the focal length: ft of the entire system at a telephoto end, and the maximum displacement: ΔWT3 of the third lens group 3G before zooming from the wide angle end to the telephoto end satisfy conditions (1) and (2).SELECTED DRAWING: Figure 1

Description

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

In recent years, a “projection-type image display device” that enlarges a planar image and displays an image as a projection image has become widespread in recent years as a projector or the like used in a presentation at a conference or a home theater.
Various types of “projection zoom lenses” for projecting a planar image to be displayed as a projection image with a variable magnification are known in the projection-type image display device.
In recent years, the “projection distance” of the projector, that is, the distance between the projector main body and the display surface on which the projection image is displayed has been shortened, and a wide angle of view is also required for the projection zoom lens.

  As a lens system with a wide angle of view, a so-called negative lead type, that is, “a lens unit that has the negative refractive power of the most magnified lens group” is known, and it is composed of a relatively small lens group of 7 lens groups. As the negative lead type projection zoom lens, for example, those disclosed in Patent Documents 1 and 2 are known.

  It is an object of the present invention to realize a novel projection zoom lens having a seven lens group configuration.

The projection zoom lens according to the present invention is a projection zoom lens that projects a magnified planar image with a variable magnification, and in order from the magnification side to the reduction side, a first lens group having negative refractive power, A second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a positive refractive power, and a negative or positive refractive power. A sixth lens group, a seventh lens group having a positive refractive power, an aperture stop between the fourth lens group and the fifth lens group, and from the second lens group during zooming. By moving up to the sixth lens group on the optical axis, the distance between adjacent groups of the first to seventh lens groups changes, and the focal length of the entire system at the wide-angle end: fw, Focal length: ft, Zoomin from wide-angle end to telephoto end Maximum movement amount to the expansion side of the third lens group upon: DerutaWT3 is, conditions:
(1) 1.5 <ft / fw <3.0
(2) 1.0 <1 / (ΔWT3 / fw) <11.0
Satisfied.

  According to the present invention, a novel projection zoom lens having a seven-lens group configuration can be realized.

It is a figure for demonstrating Example 1 of the zoom lens for projection. It is a figure for demonstrating Example 2 of the zoom lens for projection. It is a figure for demonstrating Example 3 of the zoom lens for projection. It is a figure for demonstrating Example 4 of the zoom lens for projection. It is a figure for demonstrating Example 5 of the zoom lens for projection. FIG. 3 is a diagram illustrating data of a projection zoom lens according to Example 1. FIG. 4 is a diagram illustrating various parameters of the projection zoom lens according to the first exemplary embodiment. 6 is a diagram illustrating data of a projection zoom lens according to Example 2. FIG. 6 is a diagram illustrating various parameters of a projection zoom lens according to Embodiment 2. FIG. 6 is a diagram illustrating data of a projection zoom lens according to Example 3. FIG. 6 is a diagram illustrating various parameters of a projection zoom lens according to Example 3. FIG. FIG. 6 is a diagram illustrating data of a projection zoom lens according to Example 4. FIG. 6 is a diagram illustrating various parameters of a projection zoom lens according to Example 4. FIG. 10 is a diagram illustrating data of a projection zoom lens according to Example 5. FIG. 10 is a diagram illustrating various parameters of a projection zoom lens according to Example 5. FIG. 3 is an aberration diagram at the wide-angle end of the projection zoom lens according to Example 1; FIG. 4 is an aberration diagram at the telephoto end of the projection zoom lens according to Example 1; FIG. 6 is an aberration diagram at a wide-angle end of the projection zoom lens according to Example 2. FIG. 6 is an aberration diagram at the telephoto end of the projection zoom lens according to Example 2; FIG. 10 is an aberration diagram at a wide-angle end of the projection zoom lens according to Example 3; FIG. 10 is an aberration diagram at a telephoto end of the projection zoom lens according to Example 3; FIG. 10 is an aberration diagram at a wide-angle end of the projection zoom lens according to Example 4; FIG. 10 is an aberration diagram at a telephoto end of the projection zoom lens according to Example 4; FIG. 10 is an aberration diagram at a wide-angle end of the projection zoom lens according to Example 5; FIG. 10 is an aberration diagram at a telephoto end of the projection zoom lens according to Example 5; It is a figure which shows two examples of embodiment of the image display apparatus for projection.

Hereinafter, embodiments will be described.
1 to 5 show five embodiments of the projection zoom lens. These five examples correspond to Examples 1 to 5 described later in the order shown.
1 to 5, the upper diagram shows the lens arrangement at the “wide-angle end”, and the lower diagram shows the lens arrangement at the “telephoto end”.
In these figures, the left side of the figure is the “enlarged side”, that is, the side on which the projected image is projected, and the right side of the figure is the reduced side, ie, the “side on which the planar image is displayed”.
In order to avoid complications, the symbols are shared in these drawings.
1 to 5, “1G” is the first lens group, “2G” is the second lens group, “3G” is the third lens group, “4G” is the fourth lens group, and “5G” is the fifth lens. “6G” represents a sixth lens group, and “7G” represents a seventh lens group.
In the embodiment shown in FIGS. 1 to 5, “a projection zoom lens used in a three-plate projector using three liquid crystal panels for displaying three primary color images” is assumed, and the symbol “PR” in FIG. The composition prism is shown. “S” indicates an aperture stop, “OI” indicates an image display surface, that is, a panel surface of a liquid crystal panel, and is also referred to as “planar image OI” in the following.

The first lens group 1G has “negative refractive power”, the second lens group 2G has “positive refractive power”, and the third lens group 3G has “negative refractive power”.
The fourth lens group 4G and the fifth lens group 5G both have “positive refractive power”, the sixth lens group 6G has “negative or positive refractive power”, and the seventh lens group 7G has “positive power”. Refracting power ".
In other words, the projection zoom lens according to each embodiment shown in FIGS. 1 to 5 is a projection zoom lens that projects a magnified planar image OI with a variable magnification.
The projection zoom lens includes a first lens group 1G having a negative refractive power, a second lens group 2G having a positive refractive power, and a third lens group having a negative refractive power in order from the enlargement side to the reduction side. 3G, fourth lens group 4G having positive refractive power, fifth lens group 5G having positive refractive power, sixth lens group 6G having negative or positive refractive power, and seventh lens group having positive refractive power 7G, and an aperture stop S is provided between the fourth lens group 4G and the fifth lens group 5G.

  During zooming, the second lens group 2G to the sixth lens group 6G move on the optical axis to change the adjacent group spacing of the first lens group 1G to the seventh lens group 7G.

  The first lens group 1G and the seventh lens group 7G are fixed groups with respect to zooming, and are fixed during zooming.

The zoom lens for projection according to the present invention has a focal length of the entire system at the wide angle end: fw, a focal length of the entire system at the telephoto end: ft, and an enlargement side of the third lens group during zooming from the wide angle end to the telephoto end. The maximum amount of movement to: ΔWT3 is the condition:
(1) 1.5 <ft / fw <3.0
(2) 1.0 <1 / (ΔWT3 / fw) <11.0
Satisfied.

In each of the embodiments described with reference to FIGS. 1 to 5, as described above, the color combining prism PR is provided on the optical path between the lens surface closest to the reduction side and the planar image OI.
Condition (1) is a condition for determining an appropriate range of the ratio of the focal lengths at the wide-angle end and the telephoto end: ft / fw, that is, the so-called zoom ratio. That is, in the above configuration of the projection zoom lens according to the present invention, satisfying the condition (2) makes it possible to realize good optical performance in the “zoom ratio range” of the condition (1).
When the parameter of condition (2): 1 / (ΔWT3 / fw) increases, the amount of displacement of the third lens group accompanying zooming decreases. Since the first lens group 1G and the seventh lens group 7G are fixed groups with respect to zooming, the larger the value of the parameter in the condition (2), the more advantageous the downsizing of the projection zoom lens. However, if the upper limit value of the condition (2) is exceeded, spherical aberration tends to be overcorrected on the telephoto side, and it is difficult to achieve good optical performance.

  Further, if the parameter value of the condition (2) is small, it becomes easy to correct spherical aberration and coma well throughout the entire zoom range. However, if the lower limit value of the condition (2) is exceeded, the projection zoom lens Miniaturization is likely to be difficult.

  The third lens group of the projection zoom lens according to the present invention can be composed of one or more “lenses having negative refractive power”. Hereinafter, the “lens having negative refractive power” is referred to as “negative lens”, and the “lens having positive refractive power” is referred to as “positive lens”.

The third lens group can also be composed of “one negative lens”. In each of the embodiments shown in FIGS. 1 to 5, the third lens group 3G is composed of one negative lens.
The fourth lens group can be composed of “one or more positive lenses”. That is, the fourth lens group can be composed of one positive lens. In each of the embodiments shown in FIGS. 1 to 5, the fourth lens group 4G is composed of one positive lens.

The projection zoom lens according to the present invention has the following conditions in addition to the above conditions (1) and (2):
(3) Nd ₃ <1.65
(4) 0.3 <1 / (ΔWT4 / fw) <1.0
(5) 1.75 <Nd ₄
(6) 40.0 <νd ₄
It is preferable to satisfy any one or more of the above.

In conditions (3) to (6), “Nd ₃ ” is the “average value of refractive index at the d-line” of the lenses constituting the third lens group, “fw” is the focal length of the entire system at the wide angle end, and “ft” "is the focal length of the entire system at the telephoto end," ΔWT4 "is the maximum amount of movement of the fourth lens group during zooming to the telephoto end from the wide-angle end," Nd ₄ "is the lens constituting the fourth lens group" The average value of the refractive index at the d-line ”. “Νd ₄ ” is an “average value of Abbe number” of the lenses constituting the fourth lens group.

Condition (3) is a condition that can preferably realize the negative refractive power of the third lens group. Parameter: The larger the Nd ₃ , the stronger the negative refractive power of the third lens group, which is advantageous for widening the angle. However, when the upper limit of the condition (3) is exceeded, the Petzval sum is It becomes large and it becomes difficult to achieve good optical performance.

  When the parameter of condition (4): 1 / (ΔWT4 / fw) increases, the amount of displacement of the fourth lens group accompanying zooming decreases. Since the first lens group 1G and the seventh lens group 7G are fixed groups with respect to zooming, the larger the value of the parameter in the condition (4), the more advantageous is the compactness of the projection zoom lens. ) Exceeds the upper limit value, the amount of displacement of the fourth lens unit due to zooming is small, and precise displacement of the fourth lens unit becomes difficult during zooming.

Moreover, if the lower limit value of the condition (4) is exceeded, it tends to be disadvantageous for downsizing.
Condition (5) is a condition that allows the positive refractive power of the fourth lens group to be suitably realized. The larger the parameter: Nd ₄ , the stronger the positive refractive power of the fourth lens group. The projection zoom lens can be made compact and the zoom ratio can be increased.

  However, if the lower limit value of the condition (5) is exceeded, the positive refractive power of the fourth lens group becomes weak, and the amount of “coma aberration, spherical aberration” that occurs at the wide-angle end and the telephoto end tends to differ greatly. Tends to be difficult.

  When the lower limit of condition (6) is exceeded, the difference between various aberrations such as axial chromatic aberration and lateral chromatic aberration that occur on the wide-angle side and the telephoto side tends to be large, and it is difficult to satisfactorily correct various aberrations.

A few additional remarks about conditions (3), (5), and (6).
As described above, “Nd ₃ ” is the “average refractive index at the d-line” of the lenses constituting the third lens group, and “Nd ₄ ” is the “refractive index at the d-line” of the lenses constituting the fourth lens group. “Average value of” and “νd ₄ ” are “average value of Abbe number” of the lenses constituting the fourth lens group.

  As described above, the third lens group can be composed of “one negative lens”, and the fourth lens group can be composed of “one positive lens”.

  Therefore, the so-called “average value” described above is “the refractive index and Abbe number of this one lens” when the third lens group and the fourth lens group are each one lens. It is.

The projection zoom lens according to the present invention satisfies any one or more of the conditions (3) to (6) together with the condition (2), so that “good” in the zoom ratio range specified by the condition (1). Realization of a good optical performance becomes easy.
By satisfying any one or more of the conditions (3) to (6) together with the conditions (1) and (2), the effects of these conditions can be obtained, but together with the conditions (1) and (2) Needless to say, it is most preferable to satisfy all of the conditions (3) to (6).
Various methods are available for focusing, that is, “focusing”. In focusing, “the entire first lens group or one or more lenses included in the first lens group” moves in the optical axis direction. By doing so, the focusing mechanism can be simplified.
Further, the seventh lens group having a positive refractive power can be constituted by “one positive lens”. In each of the embodiments shown in FIGS. 1 to 5, the seventh lens group 7G is constituted by “only one positive lens”, and the seventh lens group is constituted by one positive lens. The configuration of the projection zoom lens can be simplified.

The projection zoom lens according to the present invention can be used in a projection type image display apparatus that displays a planar image displayed on an image display element with a variable magnification.
Specific examples of the projection zoom lens will be described below.
"Example 1"
In Example 1, the lens configuration is shown in FIG.
Data of the projection zoom lens of Example 1 is shown in FIG.
In FIG. 6, “i” in the uppermost column is a parameter representing a surface (the lens surface and the surface of the aperture stop S, the surface of the color combining prism PR) counted from the enlargement side, and “IMG” is a plane image. The surface to be displayed.
“R” is a radius of curvature, “D” is a surface interval, “j” is a parameter representing a lens counted from the magnification side, and “PR” is a color composition prism. “N” is the refractive index of the d-line, and “ν” is the Abbe number. The same applies to the second to fifth embodiments.

FIG. 7 shows various parameters of the projection zoom lens of Example 1.
7A shows the focal length at the wide-angle end, the intermediate focal length (shown as intermediate), and the telephoto end. (B) is the surface interval at the wide-angle end, the middle, and the telephoto end of the portion of the surface interval “variable” in the data shown in FIG. 6, and (c) is the value of the parameter (1) to (6) ( Conditional expressions (1) to (6) are shown).

  (D) shows the surface spacing (upper table) between adjacent lens groups of the first lens group 1G to the seventh lens group 7G at the wide angle end (WIDE), the intermediate focal length (MEAN), and the telephoto end (TELE); The displacement amounts (table below) of zooming of the second lens group 2G to the seventh lens group 7G are shown. (E) is a value of the amount applied to each parameter of the conditions (1) to (6).

  The same applies to Examples 2 and below.

"Example 2"
In Example 2, the lens configuration is shown in FIG.
The data of the projection zoom lens of Example 2 is shown in FIG.
FIG. 11 shows various parameters of the zoom lens for projection according to the second embodiment, following FIG.

"Example 3"
In Example 3, the lens configuration is shown in FIG.
Data of the projection zoom lens of Example 3 is shown in FIG.
FIG. 13 shows various parameters of the zoom lens for projection according to the third embodiment, following FIG.

Example 4
In Example 4, the lens configuration is shown in FIG.
Data of the projection zoom lens of Example 4 is shown in FIG.
FIG. 15 shows various parameters of the zoom lens for projection according to the fourth embodiment, following FIG.

"Example 5"
In Example 5, the lens configuration is shown in FIG.
Data of the projection zoom lens of Example 5 is shown in FIG.
FIG. 17 shows various parameters of the zoom lens for projection according to the fifth embodiment, following FIG.

The range of fluctuation of the half angle of view accompanying zooming is as follows.
Example 1 36.1 degrees to 20.0 degrees
Example 2 36.1 degrees to 20.0 degrees
Example 3 40.1 degrees to 26.4 degrees
Example 4 36.1 degrees to 20.0 degrees
Example 5 41.5 degrees to 26.0 degrees
Among Examples 1 to 5, in Examples 1, 3, 4, and 5, the sixth lens group 6G has a negative refractive power, and in Example 2, the sixth lens group 6G has a positive refractive power. Have
In the projection zoom lenses of Examples 1 to 5, in order to perform focusing from infinity to a finite distance, the entire system of the first lens group 1G (Examples 1, 3, 5) or the first lens group One or more lenses (Examples 2 and 4) included in 1G are moved in the optical axis direction.

FIG. 16 shows aberration diagrams at the wide-angle end of the projection zoom lens of Example 1. FIG.
FIG. 17 shows aberration diagrams of the projection zoom lens of Example 1 at the telephoto end.
FIG. 18 is an aberration diagram at the wide-angle end of the projection zoom lens according to Example 2.
FIG. 19 is an aberration diagram at the telephoto end of the projection zoom lens of Example 2.
FIG. 20 shows aberration diagrams at the wide-angle end of the projection zoom lens according to Example 3.
FIG. 21 shows aberration diagrams at the telephoto end of the projection zoom lens according to Example 3.
FIG. 22 is an aberration diagram at the wide-angle end of the projection zoom lens according to Example 4.
FIG. 23 shows aberration diagrams at the telephoto end of the projection zoom lens according to Example 4.
FIG. 24 is an aberration diagram at the wide-angle end of the projection zoom lens according to Example 5.
FIG. 25 shows aberration diagrams at the telephoto end of the projection zoom lens of Example 5.
Each of these aberration diagrams is calculated using the “projection image displayed on the enlargement side as the object plane” and the position of the “planar image” on the reduction side as the image plane as described above.
“Y” in the aberration diagram is the maximum image height, “½ of the diagonal length of the planar image OI”, and “14.6 mm” throughout Examples 1 to 5. In the coma aberration diagram, 0H to 1H are values obtained by standardizing 14.6 mm as 1H and 0 mm as 0H.

In each aberration diagram, the left diagram shows spherical aberration, astigmatism, and distortion, and the right diagram shows coma. In the spherical aberration and coma aberration diagrams, “R” represents red light having a wavelength of 620 nm, “G” represents green light having a wavelength of 540 nm, and “B” represents blue light having a wavelength of 460 nm. Further, astigmatism and distortion are related to the green light. In astigmatism, “T” indicates tangential, and “S” indicates sagittal.
As is apparent from each aberration diagram, in each of the examples, good performance is realized at both the wide-angle end and the telephoto end.

Hereinafter, two embodiments of the projection type image display apparatus will be described with reference to FIG.
Each of the projection type image display apparatuses shown in FIG. 26 is a projector, and is hereinafter referred to as projectors PR1 and PR2. In order to avoid complication, the projection type zoom lens is indicated by “reference numeral 4”.
A projector PR1 shown in FIG. 26A is a three-plate projector using a liquid crystal panel, and three liquid crystal panels PR, PG, and PB are used as shown. A “red component image of the projection image” is displayed on the liquid crystal panel PR, and this image is illuminated with red illumination light having a wavelength of 620 nm emitted from the illumination device LR. The red illumination light is intensity-modulated by the red component image displayed on the liquid crystal panel LR and enters the color combining prism PR.

  The “green component image of the projected image” is displayed on the liquid crystal panel PG, and this image is illuminated with green illumination light having a wavelength of 540 nm emitted from the illumination device LG. The green illumination light is intensity-modulated by the green component image displayed on the liquid crystal panel LG and enters the color combining prism PR.

  The “blue component image of the projected image” is displayed on the liquid crystal panel PB, and this image is illuminated with blue illumination light having a wavelength of 460 nm emitted from the illumination device LB. The blue illumination light is intensity-modulated by the blue component image displayed on the liquid crystal panel LB and enters the color combining prism PR. The liquid crystal panels PR, PG, PB, the illumination devices LR, LG, LB and the like are controlled by the control unit CT.

  In this way, the respective color lights incident on the color combining prism are combined by the color combining prism, incident on the projection zoom lens 4, and enlarged and projected on the screen S as a color image.

  As the projection zoom lens 4, any one of claims 1 to 9 can be used. Specifically, the projection zoom lens 4 is one according to any of the first to fifth embodiments described above in combination with the color synthesis prism PR. Can be suitably used.

A projector PR2 shown in FIG. 26B is an example in which DMD3 is adopted as an image display element for displaying a planar image.
The projector PR2 includes an illumination system 2, a DMD 3 that is an image display element, and a projection zoom lens 4.

  As the projection zoom lens 4, the one described in any one of claims 1 to 9, specifically, any one of Examples 1 to 5 can be used. Since the projector PR2 does not use the color synthesizing prism PR, the back focus: Bf is equal to “the optical path length between the lens surface closest to the reduction side and the planar image on the DMD 3”.

  The “lights of the three colors R, G, and B” are temporally separated from the illumination system 2 and irradiated onto the display surface of the DMD 3, and at the timing when each color light is irradiated, “a minute mirror corresponding to each pixel ( Control the "tilt of the micromirror".

  In this way, the “planar image to be projected” is displayed on the display surface of the DMD 3, and the light whose intensity is modulated by the planar image is imaged on the screen S by the projection zoom lens 4. Magnified projection.

  The illumination system 2 includes a light source 21, a condenser lens CL, an RGB color wheel CW, and a mirror M, and it is necessary to “ensure a certain amount of space” for arranging the light source 21.

For this reason, it is necessary to increase the incident angle of the illumination light incident on the DMD 3 from the illumination system 2 to some extent. Due to the above-described relationship between the space between the projection zoom lens 4 and the illumination system 2, it is necessary to secure the back focus of the projection zoom lens 4 to some extent, and the mirror M is used to secure the incident angle of illumination light. The necessary back focus is secured by the projection zoom lens 4.
The condenser lens CL, the RGB color wheel CW, and the mirror M constitute an “illumination optical system”. A “control unit” that controls the illumination optical system, the light source 21, and the like is not shown in FIG.

As described above, according to the present invention, the following projection zoom lens and projection type image display apparatus can be realized.
[1]
A projection zoom lens for projecting a planar image (OI) with a variable magnification, and in order from the magnification side to the reduction side, a first lens group (1G) having a negative refractive power, a positive refractive power A second lens group (2G) having negative refractive power, a third lens group (3G) having negative refractive power, a fourth lens group (4G) having positive refractive power, and a fifth lens group (5G having positive refractive power) ), A sixth lens group (6G) having negative or positive refractive power, a seventh lens group (7G) having positive refractive power, and the fourth lens group (4G) and the fifth lens group ( 5G) and an aperture stop (S) between the second lens group (2G) and the sixth lens group (6G) during zooming, the first lens group ( 1G) to the seventh lens group (7G) have a different group interval, and the focus of the entire system at the wide angle end Distance: fw, the focal length of the entire system at the telephoto end: ft, the maximum movement amount to the expansion side of the third lens group upon zooming from the wide-angle end to the telephoto end: DerutaWT3 is, conditions:
(1) 1.5 <ft / fw <3.0
(2) 1.0 <1 / (ΔWT3 / fw) <11.0
Zoom lens for projection satisfying the above (Examples 1 to 5).

[2]
[1] The projection zoom lens according to [1], wherein the third lens group (3G) includes one or more lenses having negative refractive power (Examples 1 to 5). .

[3]
The projection zoom lens according to [1] or [2], wherein an average value of refractive index Nd _{3 at} the d-line of the lenses constituting the third lens group (3G) is:
(3) Nd ₃ <1.65
Zoom lens for projection satisfying the above (Examples 1 to 5).

[4]
The projection zoom lens according to any one of [1] to [3], wherein the focal length of the entire system at the wide-angle end: fw, the focal length of the entire system at the telephoto end: ft, from the wide-angle end to the telephoto end The maximum moving amount: ΔWT4 of the fourth lens group (4G) during zooming is as follows:
(4) 0.3 <1 / (ΔWT4 / fw) <1.0
Zoom lens for projection satisfying the above (Examples 1 to 5).

[5]
The projection zoom lens according to any one of [1] to [4], wherein the fourth lens group (4G) includes one or more lenses having positive refractive power. Zoom lens (Examples 1 to 5).

[6]
[1] to a projection zoom lens according to any one of [5], wherein the fourth lens constituting the lens group to (4G), the average value of the refractive index at the d-line: Nd ₄ is, conditions :
(5) 1.75 <Nd ₄
Zoom lens for projection satisfying the above (Examples 1 to 5).

[7]
[1] to a projection zoom lens according to any one of [6], an average Abbe number of the d-line of the lenses constituting the fourth lens group (4G): [nu] d ₄ condition:
(6) 40.0 <νd ₄
Zoom lens for projection satisfying the above (Examples 1 to 5).

[8]
The projection zoom lens according to any one of [1] to [7], wherein one or more lenses included in the entire first lens group (1G) or the first lens group (1G) during focusing Zoom lens for projection in which the first lens moves in the optical axis direction (Examples 1 to 5).
[9]
The projection zoom lens according to any one of [1] to [8], wherein the seventh lens group (7G) includes only one lens having a positive refractive power. Zoom lens (Examples 1 to 5).

[10]
A projection-type image display device (PR1, PR2) that magnifies and displays a planar image displayed on the image display elements (PR, PG, PB, 3) with a variable magnification, and expands the planar image with a variable magnification. A projection type image display device using the projection zoom lens described in any one of [1] to [9] as a projection zoom lens (4) to be projected (FIG. 26).

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

1G first lens group
2G second lens group
3G third lens group
4G 4th lens group
S Aperture stop
5G 5th lens group
6G 6th lens group
7G 7th lens group
PR color composite concave prism
OI plane image

JP 2011-28123 A JP 2008-275713 A

Claims (10)

A projection zoom lens that magnifies and projects a planar image at a variable magnification, and in order from the magnification side to the reduction side, a first lens group having a negative refractive power and a second lens group having a positive refractive power A third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative or positive refractive power, and positive refraction A seventh lens group having power, and having an aperture stop between the fourth lens group and the fifth lens group;
During zooming, the distance from the second lens group to the sixth lens group moves on the optical axis, so that the group interval of the first to seventh lens groups changes,
The focal length of the entire system at the wide-angle end: fw, the focal length of the entire system at the telephoto end: ft, and the maximum amount of movement of the third lens group to the magnification side during zooming from the wide-angle end to the telephoto end: ΔWT3 conditions:
(1) 1.5 <ft / fw <3.0
(2) 1.0 <1 / (ΔWT3 / fw) <11.0
Projection zoom lens that satisfies the requirements. The projection zoom lens according to claim 1,
A projection zoom lens, wherein the third lens group includes one or more lenses having negative refractive power. The projection zoom lens according to claim 1 or 2,
The average value of the refractive index at the d-line: Nd _{3 of} the lenses constituting the third lens group is:
(3) Nd ₃ <1.65
Projection zoom lens that satisfies the requirements. A projection zoom lens according to any one of claims 1 to 3,
The focal length of the entire system at the wide-angle end: fw, the focal length of the entire system at the telephoto end: ft, and the maximum amount of movement of the fourth lens group during zooming from the wide-angle end to the telephoto end: ΔWT4.
(4) 0.3 <1 / (ΔWT4 / fw) <1.0
Projection zoom lens that satisfies the requirements. The projection zoom lens according to any one of claims 1 to 4,
A zoom lens for projection, wherein the fourth lens group includes one or more lenses having positive refractive power. A projection zoom lens according to any one of claims 1 to 5,
The average value of the refractive index at the d-line of the lenses constituting the fourth lens group: Nd ₄ is:
(5) 1.75 <Nd ₄
Projection zoom lens that satisfies the requirements. A projection zoom lens according to any one of claims 1 to 6,
Average value of Abbe number of d-line of the lenses constituting the fourth lens group: νd ₄ is a condition:
(6) 40.0 <νd ₄
Projection zoom lens that satisfies the requirements. A projection zoom lens according to any one of claims 1 to 7,
A zoom lens for projection in which the entire system of the first lens group or at least one lens included in the first lens group moves in the optical axis direction during focusing. A projection zoom lens according to any one of claims 1 to 8,
The projection zoom lens, wherein the seventh lens group is composed of only one lens having a positive refractive power. A projection-type image display device that displays the planar image displayed on the image display element with a variable magnification and a projection display,
10. A projection type image display apparatus using the projection zoom lens according to claim 1 as a projection zoom lens that projects a planar image with a variable magnification. 10.

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