JP5510243B2 - Wide angle lens system and projector apparatus using the same - Google Patents

Description

  The present invention relates to a wide-angle lens with a small lens aperture for enlarging and projecting an image on a screen or the like, and a projector apparatus using the same.

  In recent years, DMD (digital micromirror device) displays images by arranging microscopic micromirrors (mirror elements) on a plane corresponding to pixels and mechanically controlling the angle of each mirror surface using micromachine technology. ) Has been put to practical use, and is characterized by a faster response speed and a brighter image than a liquid crystal panel that has been widely used in this field. It is rapidly spreading because it is suitable for realizing.

When a DMD is used as a light valve in a projector device, a DMD-specific restriction occurs for a projection lens that is used simultaneously.
The first restriction relates to the F value of the projection lens, which is considered to be the largest restriction in developing a small projector device.
Currently, in the DMD, when the image is generated, the turning angle to represent ON and OFF of the micromirror is ± 12 °, which enables effective reflected light (effective light) and invalid reflected light (ineffective light). ).
Therefore, in a projector device using a DMD as a light valve, it is necessary to capture effective light and not to catch invalid light. From this condition, the F value of the projection lens can be derived, that is, F = 2. 4
Actually, there is a demand for capturing a light amount as much as possible, and therefore, a smaller F value is often required in consideration of a decrease in contrast in a range where there is no actual harm.

The second restriction relates to the arrangement with the light source system.
In order to reduce the size, the image circle of the projection lens is desired to be as small as possible. Therefore, the arrangement of the light source system for allowing the projection light beam to enter the DMD is limited.
In order to make the effective light from the DMD incident on the projection lens, the light source system is installed in substantially the same direction (adjacent) as the projection lens.
Further, the projection lens and the light source system are used between the light valve side lens and the light valve (that is, generally back focus) of the projection lens. A back focus must be provided, and at the same time, it is necessary to design a small lens system on the light valve side in order to secure a light guide space from the light source.
From the standpoint of optical design of the projection lens, this is a constraint that the pupil position on the light valve side is located near the rear of the projection lens.
On the other hand, in order to improve the performance of the projection lens, it is necessary to combine a large number of lenses. When a large number of lenses are arranged, the total length of the projection lens requires a certain length. If the total length is long, the lens having the entrance pupil position on the rear side is a problem contrary to the miniaturization in which the front lens diameter is naturally increased.

In this way, although there are major restrictions on development, a projector device that employs DMD as a light valve is advantageous over other methods in terms of miniaturization, and is now convenient for presentations. Portable portable compact projectors have become widespread, centering on new data projectors.
In addition, in order to make the device itself compact, there is a strong demand for downsizing of the projection lens used as a matter of course. On the other hand, there is also a demand for multiple functions, and various aberrations The image quality as a result of correction sufficiently satisfies the specifications of the DMD to be used, as well as a large image circle to adopt a so-called shift configuration in which the center of the DMD and the optical axis of the projection lens are shifted. Therefore, a lens having a large angle of view has been demanded.
In the projection lens developed with such specifications, the aperture of the front lens group tends to be larger than desired, which greatly affects the thickness of the projector device.
However, it is important to reduce the thickness of a projector device that is assumed to be portable, and it is the most important factor for projector devices that are often used with laptop personal computers. It can also be said.
As means for solving this problem, there is an example of a compact design method for a projection lens as disclosed in Japanese Patent Application Laid-Open No. 2004-271668 (Patent Document 1).

JP 2004-271668 A

However, according to the proposal of Patent Document 1, when the 0.7-inch DMD is used, the effective diameter of the front lens is 39 mm to 42 mm, and at least the thickness of the projector device cannot be 50 mm or less.
When this thickness is actually carried with a notebook type personal computer or the like, the thickness is still unsatisfactory.

  In view of the above-described circumstances, the present invention is suitable for the characteristics of a light valve that forms an image by changing the reflection direction of light, such as DMD, and enlarges and projects an image from the light valve on a screen or other wall surface. Realizing a wide-angle lens with high imaging performance and a small lens diameter for applications, it is compact and bright, and is a thin projector device that is portable and has high image quality that can project a large screen even in a limited space such as a small conference room. The purpose is to provide.

In order to achieve the above object, a wide-angle lens according to the first aspect of the present invention includes:
In order from the enlargement side, the first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, and a third lens group having a positive refractive power as a whole,
The first lens group includes, in order from the magnifying side, a meniscus-shaped lens having a negative refractive power (hereinafter referred to as a negative lens), a lens having a positive refractive power (hereinafter referred to as a positive lens), a negative lens, and a magnifying lens. Consists of a concave meniscus negative lens on the side and a lens having positive refractive power,
The second lens group includes four lenses, a negative lens, a positive lens, and a cemented system of the negative lens and the positive lens in order from the magnification side, and the third lens group includes one positive lens. A wide angle lens,
The following conditional expression (1) is satisfied with respect to the composite focal length of the first lens group:
The following conditional expression (2) is satisfied with respect to the combined focal length of the second lens group:
The following conditional expression (3) is satisfied with respect to the distance on the optical axis from the magnifying side surface of the lens arranged on the most magnifying side of the first lens group to the in-focus position:
The following conditional expression (4) is satisfied with respect to the distance on the optical axis between the reduction side surface of the lens arranged closest to the reduction side of the second lens group and the enlargement side surface of the lens arranged in the third lens group: ,
The following conditional expression (5) is satisfied with respect to the power of the lens arranged on the most magnifying side of the first lens group and the power of the lens arranged on the second lens from the magnifying side of the first lens group,
Regarding the shape of the reduction side surface of the lens disposed on the third lens from the magnification side of the first lens group and the shape of the magnification side surface of the lens disposed on the fourth lens from the magnification side of the first lens group, the following conditional expression ( 6) is satisfied,
The following conditional expression (7) is satisfied regarding the dispersion characteristics of the glass material used for each lens arranged in the first lens group,
The following conditional expression (8) is satisfied with respect to the power of the lens arranged on the most magnifying side of the second lens group,
The following conditional expression (9) is satisfied with respect to the shape of the reduction side surface of the lens arranged closest to the magnification side of the second lens group and the shape of the magnification side surface of the lens arranged second from the magnification side of the second lens group. Satisfied,
The following conditional expression (10) is satisfied with respect to the power of the lens disposed on the third lens from the magnification side in the second lens group and the power of the lens disposed on the most reduction side in the third lens group,
A wide angle lens satisfying the following conditional expression (11) with respect to dispersion characteristics of a glass material used for each lens constituting the second lens group.
_{(1) -0.5 <f / f} I <-0.1
(2) 0.4 <f / f II <0.7
(3) 4.0 <TL / f <7.0
(4) 1.4 <fb / f <2.0
_{(5) -1.2 <f 2 /} f 1 <-0.6
(6) −1.2 <r ₆ / r ₇ <−0.6
(7) 10 <(V ₁ + V ₃ + V ₄ ) / 3− (V ₂ + V ₅ ) / 2
(8) -0.5 <f / f 6 <-0.1
(9) 0.4 <r ₁₂ / r ₁₃ <0.7
_{(10) -1.6 <f 8 /} f 9 <-0.8
_{(11) 30 <(V 7} + V 9) / 2- (V 6 + V 8) / 2
However,
f: Combined focal length of the entire lens system (in-focus state at a magnification side object distance of 2000 mm from the most magnified side surface of the first lens group)
f _I : Synthetic focal length of the first lens group f _II : Synthetic focal length of the second lens group TL: On the optical axis from the magnifying side surface of the lens arranged closest to the magnifying side to the in-focus position Distance (focused on the magnifying side object distance of 2000 mm from the most magnifying side of the first lens group)
fb: distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side in the second lens group to the enlargement side surface of the lens arranged in the third lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 2000mm)
f ₁ : Focal length of the lens arranged closest to the magnifying side in the first lens group f ₂ : Focal length of lens arranged on the _second lens from the magnifying side in the first lens group r ₆ : Enlarged in the first lens group Radius of curvature of the reduced side surface of the lens arranged on the third lens from the side r ₇ : radius of curvature of the enlarged side surface of the lens arranged on the fourth lens from the magnifying side in the first lens unit V ₁ : most in the first lens unit Abbe number of negative lens arranged on the magnifying side V ₂ : Abbe number of positive lens arranged on the second lens from the magnifying side in the first lens group V ₃ : Arranged on the _third lens from the magnifying side in the first lens group Abbe number of the negative lens V ₄ : Abbe number of the negative lens arranged at the fourth lens from the magnification side in the first lens group V ₅ : Abbe number of the positive lens arranged at the most reduction side in the first lens group f _6: the focal point of the lens element which is disposed outermost on the magnifying side in the second lens group distances r _12: the second Les Most enlargement of the reduction side of the lens disposed on the side radius of curvature r ₁₃ in's group curvature of the magnifying side surface of the lens which is disposed from the enlargement side to the second sheet in the second lens group f _8: the second lens group Focal length of lens arranged on the third lens from the magnification side f ₉ : Focal length of lens arranged closest to the reduction side in the second lens group V ₆ : Negative lens arranged closest to the magnification side in the second lens group Abbe number V ₇ : Abbe number of the positive lens disposed on the second lens group from the magnification side in the second lens group V ₈ : Abbe number of the negative lens disposed on the third lens sheet from the magnification side in the second lens group V ₉ : Abbe number of the positive lens arranged closest to the reduction surface in the second lens group

In the above wide-angle lens,
It is preferable to perform focusing by moving the second lens group.

In order to achieve the above object, a projector device according to a second aspect of the present invention provides:
A wide-angle lens is provided.

According to the present invention, a compact wide-angle lens with high imaging performance suitable for the characteristics of a light valve such as a DMD can be realized, and a small, thin, bright and high-quality projector can be provided.

It is a lens block diagram of 1st Example of the wide angle lens by this invention. FIG. 6 is a diagram illustrating all aberrations of the lens of the first example. It is a lens block diagram of 2nd Example of the wide angle lens by this invention. FIG. 6 is a diagram illustrating various aberrations of the lens of the second example. It is a lens block diagram of 3rd Example of the wide angle lens by this invention. It is an aberration diagram of the lens of the third example.

Hereinafter, the present invention will be described with respect to specific numerical examples.
In the wide-angle lenses of the following first to third embodiments, in order from the magnification side, a first lens group having a negative refractive power as a whole (lens group name LG1) and a second lens having a positive refractive power as a whole A group (lens group name LG2) is composed of a third lens group (lens group name LG3) having a positive refractive power as a whole.

  The first lens group LG1 includes, in order from the magnification side, a meniscus negative lens convex on the magnification side (lens name is L11, magnification side is 101, reduction side is 102), positive lens (lens Name L12, enlargement side 103, reduction side 104), negative lens (lens name L13, enlargement side 105, reduction side 106), negative lens (lens name L14, enlargement side 107, reduction side 108), positive lens (lens name L15) , An enlarged side surface 109 and a reduced side surface 110).

  The second lens group LG2 includes, in order from the enlargement side, a negative lens (lens name L21, enlargement side surface 201, reduction side surface 202), positive lens (lens name L22, enlargement side surface 203, reduction side surface 204), and negative lens (lens The lens system includes a name L23, an enlargement side surface 205, a reduction-side joining surface 206) and a positive lens (lens name L24, enlargement-side joining surface 206, reduction side 207).

The third lens group LG3 includes a single positive lens (lens name L31, enlarged side surface 301, reduced side surface 302).
Subsequently, a cover glass CG (enlarged side surface C01, reduced side surface) which is a component of a light valve such as a DMD disposed with a slight air gap between the reduced side of the third lens group LG3 and the light valve surface. C02).

Table 1 shows numerical examples of the first embodiment of the wide-angle lens of the present invention.
FIG. 1 is a diagram showing the lens configuration, and FIG. 2 is a diagram showing various aberrations thereof.

In the tables and drawings, f represents the focal length of the entire wide-angle lens system, Fno represents the F number, and 2ω represents the total angle of view of the wide-angle lens.
In addition, r is a radius of curvature, d is a lens thickness or a lens interval, nd is a refractive index with respect to the d line, and νd is an Abbe number of the d line. (Numerical value when the object distance is 2000 mm).
CA1, CA2, and CA3 in the spherical aberration diagrams in the various aberration diagrams are aberration curves at wavelengths of CA1 = 550.0 nm, CA2 = 450.0 nm, and CA3 = 620.0 nm, respectively.
In the astigmatism diagram, S indicates sagittal and M indicates meridional. In addition, unless otherwise specified throughout, the wavelength used for calculation of various values is CA1 = 550.0 nm.

Table 2 shows numerical examples of the second embodiment of the wide-angle lens of the present invention.
FIG. 3 is a diagram showing the lens configuration, and FIG. 4 is a diagram showing various aberrations thereof.

Table 3 shows numerical examples of the third embodiment of the wide-angle lens of the present invention.
FIG. 5 is a diagram showing the lens configuration, and FIG. 6 is a diagram showing various aberrations.

next,
f: Combined focal length of the entire lens system (in-focus state at a magnification side object distance of 2000 mm from the most magnified side surface of the first lens group)
f _I : Synthetic focal length of the first lens group f _II : Synthetic focal length of the second lens group TL: On the optical axis from the magnifying side surface of the lens arranged closest to the magnifying side in the first lens group to the in-focus position Distance (focused on the magnifying side object distance of 2000 mm from the most magnifying side of the first lens group)
fb: distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side in the second lens group to the enlargement side surface of the lens arranged in the third lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 2000mm)
f ₁ : Focal length of the lens arranged closest to the magnifying side in the first lens group f ₂ : Focal length of lens arranged on the _second lens from the magnifying side in the first lens group r ₆ : Enlarged in the first lens group Radius of curvature of the reduced side surface of the lens arranged on the third lens from the side r ₇ : radius of curvature of the enlarged side surface of the lens arranged on the fourth lens from the magnifying side in the first lens unit V ₁ : most in the first lens unit Abbe number of negative lens arranged on the magnifying side V ₂ : Abbe number of positive lens arranged on the second lens from the magnifying side in the first lens group V ₃ : Arranged on the _third lens from the magnifying side in the first lens group Abbe number of the negative lens V ₄ : Abbe number of the negative lens arranged at the fourth lens from the magnification side in the first lens group V ₅ : Abbe number of the positive lens arranged at the most reduction side in the first lens group f _6: the focal point of the lens element which is disposed outermost on the magnifying side in the second lens group distances r _12: the second Les Most enlargement of the reduction side of the lens disposed on the side radius of curvature r ₁₃ in's group curvature of the magnifying side surface of the lens which is disposed from the enlargement side to the second sheet in the second lens group f _8: the second lens group Focal length of lens arranged on the third lens from the magnification side f ₉ : Focal length of lens arranged closest to the reduction side in the second lens group V ₆ : Negative lens arranged closest to the magnification side in the second lens group Abbe number V ₇ : Abbe number of the positive lens disposed on the second lens group from the magnification side in the second lens group V ₈ : Abbe number of the negative lens disposed on the third lens sheet from the magnification side in the second lens group V ₉ : It is confirmed whether the following conditional expressions (1) to (11) are satisfied when the Abbe number of the positive lens arranged closest to the reduction surface in the second lens group is used.
_{(1) -0.5 <f / f} I <-0.1
(2) 0.4 <f / f II <0.7
(3) 4.0 <TL / f <7.0
(4) 1.4 <fb / f <2.0
_{(5) -1.2 <f 2 /} f 1 <-0.6
(6) −1.2 <r ₆ / r ₇ <−0.6
(7) 10 <(V ₁ + V ₃ + V ₄ ) / 3− (V ₂ + V ₅ ) / 2
(8) -0.5 <f / f 6 <-0.1
(9) 0.4 <r ₁₂ / r ₁₃ <0.7
_{(10) -1.6 <f 8 /} f 9 <-0.8
_{(11) 30 <(V 7} + V 9) / 2- (V 6 + V 8) / 2

Conditional expression (1) is a condition regarding the power of the first lens group.
The first lens group has a strong negative power and has a purpose of securing a space for arranging an optical system for illuminating a light valve such as a DMD in an air space portion between the second lens group and the third lens group. ing.
When the upper limit is exceeded, the negative power of the first lens group becomes small, and it becomes difficult to ensure the air gap between the second lens group and the third lens group. When the lower limit is exceeded, the negative power increases and the second power increases. The positive power of the lens group must be strengthened, making it difficult to balance various aberrations.

Conditional expression (2) is a condition relating to the power of the second lens group, and is a condition for balance between miniaturization and performance.
If the upper limit of conditional expression (2) is exceeded, the positive power of the second lens group becomes strong and advantageous for miniaturization, but it becomes difficult to correct aberrations. If the lower limit is exceeded, the positive power of the lens becomes weak and miniaturization is achieved. It becomes difficult to do.

Conditional expression (3) is a condition of the distance on the optical axis from the magnifying side surface of the lens arranged closest to the magnifying side in the first lens group to the in-focus position, and is a condition for miniaturization and diameter reduction.
If the upper limit is exceeded, the distance from the magnifying side of the first lens group located on the most magnifying side to the in-focus position will increase, and the lens will have a large aperture, which will impair the reduction in size and diameter, and the lower limit. Below that, it becomes difficult to balance the various aberrations.

Conditional expression (4) is a condition of the distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side in the second lens group to the enlargement side surface of the lens arranged in the third lens group. This is a condition for securing a light guide space and realizing a small size and a small diameter.
When the upper limit is exceeded, each lens of the second lens group has a large aperture, which impairs the reduction in size and diameter. When the lower limit is exceeded, it is difficult to secure a light guide space from the light source.

Conditional expression (5) is a condition regarding the power of the negative lens arranged closest to the magnification side in the first lens group and the power of the positive lens arranged second from the magnification side.
As described above, increasing the negative power of the lens arranged on the enlargement side of the first lens group secures an air space between the second lens group and the third lens group and is effective for miniaturization. Although it is a feature of the retrofocus type, it is difficult to correct distortion, so a positive lens is placed on the second lens from the enlargement side, and the power of the two lenses is appropriate to achieve miniaturization and aberration correction. Need to be allocated to.
If the upper limit is exceeded, the power of the lens arranged closest to the enlargement side of the first lens group becomes weak and it becomes difficult to correct coma, and if it falls below the lower limit, it becomes difficult to correct distortion.

Conditional expression (6) satisfies the shape of the reduction side surface of the lens disposed on the third lens from the magnification side of the first lens group and the magnification side surface of the lens disposed on the fourth lens from the magnification side of the first lens group. It is a condition related to the shape, and is a conditional expression for correcting coma aberration of the entire lens system.
While having a strong power, it has a generally symmetrical shape and a shape that fundamentally suppresses the occurrence of aberrations.
Therefore, when the upper limit is exceeded, coma aberration is undercorrected, and when the lower limit is exceeded, overcorrection is conversely performed.

Conditional expression (7) is a condition regarding the dispersion characteristics of the glass material used for each lens arranged in the first lens group, and is a condition for correcting chromatic aberration in the first lens group.
In order to correct chromatic aberration, it is necessary that the power of each lens does not become excessive. For that purpose, the Abbe number of the positive lens that satisfies the conditional expression (7) is necessary.
Below the lower limit, it becomes difficult to correct chromatic aberration.

Conditional expression (8) is a condition relating to the power of the lens arranged closest to the magnification side of the second lens group, and is a condition for correcting spherical aberration.
Spherical aberration is corrected by making divergent light emitted from the first lens group having a strong negative power substantially parallel light and making it incident on the second positive lens arranged from the magnification side of the second lens group. Is going.
If the upper limit is exceeded, the spherical aberration will be undercorrected, and if it falls below the lower limit, the spherical aberration will be overcorrected.

Conditional expression (9) is a condition regarding the shape of the reduction side surface of the lens arranged closest to the magnification side of the second lens group and the shape of the magnification side surface of the lens arranged second from the magnification side of the second lens group. Yes, it is a condition regarding correction of spherical aberration and coma difference.
When the upper limit is exceeded, the surface power ratio increases, and when the lower limit is exceeded, the surface power ratio decreases, making it difficult to correct spherical aberration and coma aberration.

Conditional expression (10) is a condition regarding the power of the lens disposed on the third lens from the magnification side in the second lens group and the power of the lens disposed on the most reduction side in the second lens group, and chromatic aberration and spherical aberration. This is a condition related to the correction.
It is necessary to dispose a strong positive power lens on the reduction side of the third lens group to guide the beam bundle emitted from the second lens group to a converged state. Since it is difficult to correct aberrations, it is necessary to use a cemented system with a negative lens.
If the upper limit is exceeded, the power of the lens arranged closest to the second lens group will become strong, and the under chromatic aberration and spherical aberration will increase. The power of the lens becomes weak, the over-chromatic aberration and the spherical aberration increase, and it becomes difficult to correct the aberration.

Conditional expression (11) is a condition for correcting chromatic aberration in the second lens group.
In order to correct axial chromatic aberration and lateral chromatic aberration, it is necessary that the power of each lens does not become excessive. For that purpose, the Abbe number of the positive lens that satisfies the conditional expression (11) is necessary. .
Below the lower limit, it becomes difficult to correct chromatic aberration.

  Table 4 collectively shows values corresponding to the conditional expressions (1) to (11) with respect to the first to third embodiments.

  As is clear from Table 4, the numerical values related to the first to third examples satisfy the conditional expressions (1) to (11), and the aberration diagrams in the respective examples (FIG. 2, 4 and 6), each aberration is corrected well.

Further, it is preferable to perform focusing by moving the second lens group.
When projection is performed while changing the magnification-side object distance, focusing is required. As a focusing method, a method of moving the first lens group, a method of moving the second lens group, a second lens group to a second lens group are used. It is also possible to take a method of moving the lens group as a unit, or a method of moving the lenses arranged from the first lens group to the second lens group into groups different from the present invention.

  However, when the magnification-side object distance is set from about 300 mm to about 3000 mm, depending on the focusing method, the performance may be deteriorated when the magnification-side object distance is changed, and the method of moving the second lens group is It is possible to reduce the performance change due to the enlargement side object distance.

  By mounting the wide-angle lens according to the present invention on the projector device in this way, the entire device can be miniaturized, and a thin projector device that is convenient for carrying can be provided.

LG1 First lens group LG2 Second lens group LG3 Third lens group CG Cover glass

Claims (3)

In order from the enlargement side, the first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, and a third lens group having a positive refractive power as a whole,
The first lens group includes, in order from the magnifying side, a meniscus-shaped lens having a negative refractive power (hereinafter referred to as a negative lens), a lens having a positive refractive power (hereinafter referred to as a positive lens), a negative lens, and a magnifying lens. Consists of a concave meniscus negative lens on the side and a lens having positive refractive power,
The second lens group includes four lenses, a negative lens, a positive lens, and a cemented system of the negative lens and the positive lens in order from the magnification side, and the third lens group includes one positive lens. A wide angle lens,
The following conditional expression (1) is satisfied with respect to the composite focal length of the first lens group:
The following conditional expression (2) is satisfied with respect to the combined focal length of the second lens group:
The following conditional expression (3) is satisfied with respect to the distance on the optical axis from the magnifying side surface of the lens arranged on the most magnifying side of the first lens group to the in-focus position:
The following conditional expression (4) is satisfied with respect to the distance on the optical axis between the reduction side surface of the lens arranged closest to the reduction side of the second lens group and the enlargement side surface of the lens arranged in the third lens group: ,
The following conditional expression (5) is satisfied with respect to the power of the lens arranged on the most magnifying side of the first lens group and the power of the lens arranged on the second lens from the magnifying side of the first lens group,
Regarding the shape of the reduction side surface of the lens disposed on the third lens from the magnification side of the first lens group and the shape of the magnification side surface of the lens disposed on the fourth lens from the magnification side of the first lens group, the following conditional expression ( 6) is satisfied,
The following conditional expression (7) is satisfied regarding the dispersion characteristics of the glass material used for each lens arranged in the first lens group,
The following conditional expression (8) is satisfied with respect to the power of the lens arranged on the most magnifying side of the second lens group,
The following conditional expression (9) is satisfied with respect to the shape of the reduction side surface of the lens arranged closest to the magnification side of the second lens group and the shape of the magnification side surface of the lens arranged second from the magnification side of the second lens group. Satisfied,
The following conditional expression (10) is satisfied with respect to the power of the lens disposed on the third lens from the magnification side in the second lens group and the power of the lens disposed on the most reduction side in the third lens group,
A wide angle lens satisfying the following conditional expression (11) with respect to dispersion characteristics of a glass material used for each lens constituting the second lens group.
_{(1) -0.5 <f / f} I <-0.1
(2) 0.4 <f / f II <0.7
(3) 4.0 <TL / f <7.0
(4) 1.4 <fb / f <2.0
_{(5) -1.2 <f 2 /} f 1 <-0.6
(6) −1.2 <r ₆ / r ₇ <−0.6
(7) 10 <(V ₁ + V ₃ + V ₄ ) / 3− (V ₂ + V ₅ ) / 2
(8) -0.5 <f / f 6 <-0.1
(9) 0.4 <r ₁₂ / r ₁₃ <0.7
_{(10) -1.6 <f 8 /} f 9 <-0.8
_{(11) 30 <(V 7} + V 9) / 2- (V 6 + V 8) / 2
However,
f: Combined focal length of the entire lens system (in-focus state at a magnification side object distance of 2000 mm from the most magnified side surface of the first lens group)
f _I : Synthetic focal length of the first lens group f _II : Synthetic focal length of the second lens group TL: On the optical axis from the magnifying side surface of the lens arranged closest to the magnifying side in the first lens group to the in-focus position Distance (focused on the magnifying side object distance of 2000 mm from the most magnifying side of the first lens group)
fb: distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side in the second lens group to the enlargement side surface of the lens arranged in the third lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 2000mm)
f ₁ : Focal length of the lens arranged closest to the magnifying side in the first lens group f ₂ : Focal length of lens arranged on the _second lens from the magnifying side in the first lens group r ₆ : Enlarged in the first lens group Radius of curvature of the reduced side surface of the lens arranged on the third lens from the side r ₇ : radius of curvature of the enlarged side surface of the lens arranged on the fourth lens from the magnifying side in the first lens unit V ₁ : most in the first lens unit Abbe number of negative lens arranged on the magnifying side V ₂ : Abbe number of positive lens arranged on the second lens from the magnifying side in the first lens group V ₃ : Arranged on the _third lens from the magnifying side in the first lens group Abbe number of the negative lens V ₄ : Abbe number of the negative lens arranged at the fourth lens from the magnification side in the first lens group V ₅ : Abbe number of the positive lens arranged at the most reduction side in the first lens group f _6: the focal point of the lens element which is disposed outermost on the magnifying side in the second lens group distances r _12: the second Les Most enlargement of the reduction side of the lens disposed on the side radius of curvature r ₁₃ in's group curvature of the magnifying side surface of the lens which is disposed from the enlargement side to the second sheet in the second lens group f _8: the second lens group Focal length of lens arranged on the third lens from the magnification side f ₉ : Focal length of lens arranged closest to the reduction side in the second lens group V ₆ : Negative lens arranged closest to the magnification side in the second lens group Abbe number V ₇ : Abbe number of the positive lens disposed on the second lens group from the magnification side in the second lens group V ₈ : Abbe number of the negative lens disposed on the third lens sheet from the magnification side in the second lens group V ₉ : Abbe number of the positive lens arranged closest to the reduction surface in the second lens group   The wide-angle lens according to claim 1, wherein the second lens group is moved for focusing.   A projector apparatus comprising the wide-angle lens according to claim 1.

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