JP2012208404A - Wide angle lens and projector device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide angle lens that projects onto a screen and the like an enlarged image from a light valve such as a DMD for forming an image by changing a reflection direction of light, has high performance, has a small lens aperture, and is compact.SOLUTION: A wide angle lens is constituted of a first lens group having negative refractive power as a whole, a second lens group having positive refractive power as a whole, a third lens group having positive refractive power as a whole, and a fourth lens group having positive refractive power as a whole in this order from an enlargement side. The first lens group is constituted by arranging eight lenses including a negative lens having a convex shape, a negative lens, a negative lens, a positive lens, a positive lens, a negative lens, and a positive lens in this order from the enlargement side. The second lens group is constituted by arranging one positive lens or is constituted by arranging two positive lenses in this order from the enlargement side. The third lens group is constituted by arranging six lenses including a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens in this order from the enlargement side. The fourth lens group is constituted by arranging one positive lens.

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 apparatus 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. Since the image circle of the projection lens is desired to be as small as possible for miniaturization, the arrangement of the light source system for inputting the projection light beam to the DMD is limited. In order to input effective light from the DMD to the projection lens, the light source system is installed in substantially the same direction (adjacent) as the projection lens. In addition, the projection lens and the light source system are used between the light valve side lens of the projection lens and the light valve (in general, the back focus), and the projection lens has a large back. In addition to providing a focus, 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, and if a large number of lenses are arranged, the total length of the projection lens needs to be a certain length. If the total length of the lens is increased, the lens having the entrance pupil position on the rear side becomes a problem contrary to the size reduction 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, it is natural that there is a strong demand for miniaturization of the projection lens used, and on the other hand, there is also a demand for multi-function, and correction of various aberrations. In addition to satisfying the specifications of the DMD used as a result of the image quality performance as a result of the above, the image circle has a large image circle in order to adopt a so-called shift configuration in which the center of the DMD and the optical axis of the projection lens are shifted. There is a demand for a wide-angle lens capable of projecting a large screen with a short projection distance. For this reason, it is necessary that the angle of view of the projection lens be as large as about 110 degrees in all angles. In the projection lens developed with such specifications, the aperture of the front lens group tends to be larger than desired, and the overall length of the projection lens becomes longer, which greatly affects the dimensions of the projector apparatus. However, it is important to reduce the size of a projector device that is assumed to be portable, and it can be said that it is the most important factor in a projector device that is often used with a notebook personal computer. . As means for solving this problem, there is an example of a projection lens widening design method as disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-156210.

JP 2007-156210 A

  However, in the proposal of Patent Document 1, the wide angle of view is realized as 111 degrees, but the total length is as large as 280 mm. Therefore, it is not possible to realize a projector having a portable size with a notebook personal computer or the like. Have difficulty.

  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. A compact wide-angle lens with high imaging performance and a small lens aperture for applications, compact and bright, with a high image quality capable of projecting a large screen even in a limited space such as a small conference room. An object of the present invention is to provide a projector device.

The present invention includes, in order from the magnification side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a third lens group having a positive refractive power as a whole, and a whole. A fourth lens group having a positive refractive power, and the first lens group in order from the magnifying side is a meniscus lens convex to the magnifying side (hereinafter, negative lens), a negative lens, A negative lens, a lens having a positive refractive power (hereinafter, positive lens), a positive lens, a negative lens, and a positive lens are arranged, and the second lens group includes one lens in order from the magnification side. The third lens group includes a positive lens, a negative lens, a positive lens, a negative lens, and a positive lens in order from the magnifying side. A fourth lens group comprising six lenses, a positive lens and a lens; , A wide-angle lens that is configured by disposing one positive 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 third 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 focusing position:
The following conditional expression (4) is satisfied with respect to the distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side of the third lens group to the enlargement side surface of the lens arranged in the fourth lens group. It is characterized by that. (Claim 1)
(1) -2.2 <f / f I <-0.8
(2) 0.2 <f / f III <0.4
(3) 11.0 <TL / f <17.0
(4) 3.4 <fb / f <4.7
f : Composite focal length of the entire lens system (focused on the magnifying side object distance of 830 mm from the most magnifying side of the first lens group)
f _I : Synthetic focal length of the first lens group f _III : Synthetic focal length of the third lens group TL: On the optical axis from the magnifying side of the lens arranged closest to the magnifying side in the first lens group to the in-focus position Distance (focused on the magnifying object distance of 830 mm from the most magnifying side of the first lens group)
fb: Distance on the optical axis between the reduction side surface of the lens arranged closest to the reduction side in the third lens group and the enlargement side surface of the lens arranged in the fourth lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 830mm)

  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 third lens group and the fourth 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 third lens group and the fourth lens group. When the upper limit is exceeded, the negative power increases and the third 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 third lens group, and is a condition for reducing the size and the performance. If the upper limit of conditional expression (2) is exceeded, the positive power of the third lens group will become strong and advantageous for miniaturization, but it will be difficult to correct aberrations. If the lower limit is exceeded, the positive power of the lens will become weak and miniaturization will occur. 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 small condition. If the upper limit is exceeded, the distance from the magnifying side surface of the lens arranged closest to the magnifying side to the in-focus position in the first lens group will be large, and the lens will have a large aperture, which will reduce the size reduction. It becomes difficult to balance 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 third lens group to the enlargement side surface of the lens arranged in the fourth lens group. This is a condition for securing a light guide space and realizing miniaturization. If the upper limit is exceeded, each lens of the third lens group has a large aperture, which impairs downsizing, and if the lower limit is exceeded, it is difficult to secure a light guide space from the light source.

2. The wide-angle lens according to claim 1, wherein the first lens group includes, in order from the magnifying side, a meniscus-shaped lens having a negative refractive power, a negative lens, a negative lens, and a positive lens. A negative lens having a refractive power (hereinafter referred to as a positive lens), a positive lens, a negative lens, and a positive lens, and arranged at the most magnification side in the first lens group; The following conditional expression (5) is satisfied with respect to the focal length of the negative lens disposed on the second lens from the magnification side in the first lens group, and is disposed on the third lens from the magnification side of the first lens group. The following conditional expression (6) is satisfied with respect to the dispersion characteristics of the glass materials used for each of the five lenses constituting the negative lens to the positive lens arranged closest to the reduction side in the first lens group. Features. (Claim 2)
(5) 0.5 <f _{I 2} / f _{I 1} <0.9
(6) 11 <(V _{I 3} + V _{I 6} ) / 2− (V _{I 4} + V _{I 5} + V _{I 7} ) / 3
However,
f _{I 1} : Focal length of the negative lens disposed closest to the magnification side in the first lens group f _{I 2} : Focal length V _{I 3 of the} negative lens disposed on the second lens from the magnification side in the first lens group Abbe number V _{I 4} of the negative lens arranged in the third lens from the magnification side in one lens group: Abbe number V _{I 5 of the} positive lens arranged in the fourth lens from the magnification side in the first lens group: First lens Abbe number V _{I 6} of the positive lens arranged in the fifth lens from the magnifying side in the group: Abbe number V _{I 7 of} negative lens arranged in the sixth lens from the magnifying side in the first lens group: In the first lens group Abbe number of positive lens arranged on the most reduction side

2. The wide-angle lens according to claim 1, wherein the second lens group is configured by arranging one positive lens in order from the magnification side, or by arranging two positive lenses, The following conditional expression (7) is satisfied with respect to the combined focal length of the second lens group. (Claim 2)
(7) 0.2 <f / f II <0.5
However,
f _II : Composite focal length of the second lens group

  Conditional expression (7) is a condition relating to the power of the second lens group. The second lens group has a function of complementing the power balance between the first lens group having a positive power and a strong negative power and the third lens group having a positive power. Aberration correction is possible. If the lower limit is exceeded, the power of the second lens group becomes weak and the light from the second lens group diverges, so that the aperture of the first lens group becomes large, and if the upper limit is exceeded, it is difficult to correct aberrations. .

2. The wide-angle lens according to claim 1, wherein the third lens group includes six lenses of a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens in order from the magnification side. The following conditional expression (8) is satisfied with respect to the focal length of the negative lens disposed on the fourth lens from the side, and the surface on the reduction side of the positive lens disposed on the most reduction side constituting the third lens group Regarding power, the following conditional expression (9) is satisfied, and the following conditional expression (10) is satisfied regarding the dispersion characteristics of the glass material used for each of the six lenses used in the third group. Features. (Claim 3)
(8) 0.5 <f / fIII ₄ <−0.3
(9) −0.5 <f / r _{III 11} <−0.3
(10) 30 <( _VIII1 + _VIII3 + _VIII5 + _VIII6 ) / 4- ( _VIII2 + _VIII4 ) / 2
However,
f _{III 4} : Focal length r _{III of the} negative lens arranged fourth from the magnification side of the third lens group ₁₁ : Radius of curvature V _III of the reduction side surface of the lens arranged closest to the reduction surface side of the third lens group ₁ : Abbe number V _{III of the} positive lens arranged closest to the enlargement side in the third lens group ₂ : Abbe number V _{III 3 of the} positive lens arranged second from the enlargement side in the third lens group ₃ : Third lens Abbe number V _{III 4} of the negative lens arranged on the third lens from the magnifying side in the group: Abbe number V _{III 5 of} positive lens arranged on the fourth lens from the magnifying side in the third lens group: In the third lens group Abbe number of positive lens arranged on the fifth lens from the magnification side V _{III 6} : Abbe number of positive lens arranged closest to the reduction side in the third lens group

  Conditional expression (8) is a condition for correcting divergent light beams from the first lens group and the second lens group, ensuring a large aperture ratio, and correcting spherical aberration and coma aberration. The third lens group has a strong positive power for guiding the diverging beam bundles emitted from the first lens group and the second lens group to a focused state, and various aberrations such as spherical aberration are generated. . The lens constituting the third lens group corrects various aberrations as a six-lens configuration including a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens from the magnification surface side. If the positive power is not appropriate, aberration correction will be insufficient. If the upper limit of conditional expression (8) is exceeded, under spherical aberration will increase, and if the lower limit is exceeded, over spherical aberration will increase, resulting in significant coma around the periphery, making it difficult to correct aberrations. In the spherical shape, aberration correction may be insufficient. In this case, the large lens diameter ratio of the entire lens system can be increased by making the lens arranged on the fifth lens from the magnification side of the third lens group an aspherical surface. This makes it possible to reduce the diameter of the entire lens system and correct spherical aberration and the like.

  Conditional expression (9) is a condition related to the shape of the reduction side surface of the lens arranged closest to the reduction side of the third lens group, and is a conditional expression for finely correcting spherical aberration and coma aberration in the entire lens system. . The spherical aberration and coma remaining without being corrected by the five lenses from the enlarged side surface of the third lens group are corrected. When the upper limit is exceeded, the correction is insufficient, and when the lower limit is exceeded, the correction is excessive.

  Conditional expression (10) is a condition for correcting chromatic aberration in the third 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 a positive lens and a negative lens satisfying conditional expression (10) is required. It becomes a necessary condition. When the lower limit is exceeded, it becomes difficult to correct chromatic aberration.

  Thus, by mounting the wide-angle lens according to the present invention on the projector apparatus, the entire apparatus can be reduced in size (claim 4), and a thin projector apparatus convenient for carrying can be 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 DMD can be realized, and a small, 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. It is a lens block diagram of 4th Example of the wide angle lens by this invention. FIG. 10 is a diagram illustrating various aberrations of the lens of the fourth example. It is a lens block diagram of 5th Example of the wide angle lens by this invention. FIG. 10 is a diagram illustrating all aberrations of the lens of the fifth example.

  Hereinafter, the present invention will be described with respect to specific numerical examples. In the compact wide-angle lenses of the following first to fifth embodiments, in order from the magnification side, the first lens group (lens group name LG1) having a negative refractive power as a whole, and the first lens group having a positive refractive power as a whole. 2 lens groups (lens group name LG2), a third lens group having a positive refractive power as a whole (lens group name LG3), and a fourth lens group having a positive refractive power as a whole (lens group name LG4). The first lens group LG1 includes, in order from the enlargement side, a negative meniscus lens convex on the enlargement side (lens name is L11, enlargement side name is 101, reduction side name is 102), negative lens ( Lens name L12, enlargement side surface 103, reduction side surface 104), negative lens (lens name L13, enlargement side surface 105, reduction side joint surface 106), positive lens (lens name L14, enlargement side joint surface 106, reduction) Surface 107), a positive lens (lens name L15, enlargement side surface 108, reduction side joint surface 109), a negative lens (lens name L16, enlargement side joint surface 109, reduction side joint surface 110), and a positive lens (lens) The second lens group LG2 is composed of a positive lens (lens name L21, enlargement side 201, reduction side joint surface in order from the enlargement side). 202) One lens is arranged, or one positive lens (lens name L22, enlargement side 202, reduction side 203) is additionally arranged, and the third lens group LG3 In order from the enlargement side, a positive lens (lens name L31, enlargement side surface 301, reduction side cementing surface 302), negative lens (lens name L32, enlargement side cementing surface 302, reduction side surface 303), positive lens (Lens name L33, enlarged side surface 304, reduced side surface 305), negative lens (lens name L34, enlarged side surface 306, reduced side surface 307), positive lens (lens name L35, enlarged side surface 308, reduced side surface 309), and positive lens ( The lens name L36, the enlarged side surface 310, and the reduced side surface 311) are arranged, and the fourth lens group L4 is constituted by arranging one positive lens (lens name L41, enlarged side surface 401, reduced side surface 402). Subsequently, a cover glass CG (enlarged side C01, reduction side), which is a component of a light valve such as DMD, which is arranged with a slight air gap between the reduction side of the fourth lens group LG4 and the light valve surface. Side surface C02) is arranged.

As is well known, the aspherical surface used in each embodiment has an aspherical formula when taking the Z axis in the optical axis direction and the Y axis in the direction orthogonal to the optical axis:
Z = (Y ² / r) / [1 + √ {1- (1 + K) (Y / r) ² }]
+ A ₃ · Y ³ + A ₄ · Y ⁴ + A ₅ · Y ⁵ + A ₆ · Y ⁶ +
Is a curved surface obtained by rotating the curve given by around the optical axis, paraxial radius of curvature: r, conic constant: K, higher order aspherical coefficients: A ₃ , A ₄ , A ₅ , A _6. To define the shape. In the notation of the conic constant and the higher-order aspheric coefficient in the table, “E and the number following it” represent “power of 10”. For example, “E-4” means 10 ⁻⁴ , and this numerical value may be multiplied by the immediately preceding numerical value.

[Example 1]
Table 1 shows numerical examples of the first embodiment of the compact wide-angle lens of the present invention. FIG. 1 is a lens configuration diagram, and FIG.
In the tables and drawings, f represents the focal length of the entire wide-angle lens system, F _no represents the F number, and 2ω represents the total angle of view (unit: degrees) of the wide-angle lens. In addition, r is a radius of curvature, d is a lens thickness or a lens interval, n _d is a refractive index with respect to the d line, and ν _d is an Abbe number of the d line (however, a numerical value that changes due to the focusing operation in the table is 101 plane The numerical value in the in-focus state with the object distance from 830 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. Unless otherwise specified throughout, the wavelength used for calculation of various values is CA1 = 550.0 nm, and the unit of length is mm.

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

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

[Example 4]
Table 4 shows numerical examples of the fourth embodiment of the compact wide-angle lens of the present invention. FIG. 7 is a lens configuration diagram, and FIG.

[Example 5]
Table 5 shows numerical examples of the fifth embodiment of the compact wide-angle lens of the present invention. FIG. 9 is a diagram showing the lens configuration, and FIG. 10 is a diagram showing various aberrations.

  Next, Table 6 collectively shows values corresponding to the conditional expressions (1) to (10) regarding the first to fifth embodiments. As is clear from Table 6, the numerical values related to the first to fifth embodiments satisfy the conditional expressions (1) to (10) and are also apparent from the aberration diagrams in the respective embodiments. Thus, each aberration is corrected well.

The invention described in the scope of claims at the beginning of the filing of the present application will be appended.
The invention described in claim 1
In order from the magnifying side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a third lens group having a positive refractive power as a whole, and a positive refractive power as a whole The first lens group includes, in order from the magnifying side, a lens having a meniscus shape convex to the magnifying side and having negative refractive power (hereinafter, negative lens), negative lens, negative lens, positive lens A lens having a refractive power (hereinafter, positive lens), a positive lens, a negative lens, and a positive lens are arranged, and the second lens group includes one positive lens in order from the magnification side. The third lens group includes, in order from the magnification side, a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens. 6 lenses are arranged, and the fourth lens group includes positive lenses. A wide-angle lens that is configured by disposing one,
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 third 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 focusing position:
The following conditional expression (4) is satisfied with respect to the distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side of the third lens group to the enlargement side surface of the lens arranged in the fourth lens group. It is characterized by that.
(1) -2.2 <f / f I <-0.8
(2) 0.2 <f / f III <0.4
(3) 11.0 <TL / f <17.0
(4) 3.4 <fb / f <4.7
f : Composite focal length of the entire lens system (focused on the magnifying side object distance of 830 mm from the most magnifying side of the first lens group)
f _I : Synthetic focal length of the first lens group f _III : Synthetic focal length of the third lens group TL: On the optical axis from the magnifying side of the lens arranged closest to the magnifying side in the first lens group to the in-focus position Distance (focused on the magnifying object distance of 830 mm from the most magnifying side of the first lens group)
fb: Distance on the optical axis between the reduction side surface of the lens arranged closest to the reduction side in the third lens group and the enlargement side surface of the lens arranged in the fourth lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 830mm)

The invention according to claim 2 is the wide-angle lens according to claim 1,
2. The wide-angle lens according to claim 1, wherein the first lens group includes, in order from the magnifying side, a meniscus-shaped lens having a negative refractive power, a negative lens, a negative lens, and a positive lens. A negative lens having a refractive power (hereinafter referred to as a positive lens), a positive lens, a negative lens, and a positive lens, and arranged at the most magnification side in the first lens group; The following conditional expression (5) is satisfied with respect to the focal length of the negative lens disposed on the second lens from the magnification side in the first lens group, and is disposed on the third lens from the magnification side of the first lens group. The following conditional expression (6) is satisfied with respect to the dispersion characteristics of the glass materials used for each of the five lenses constituting the negative lens to the positive lens arranged closest to the reduction side in the first lens group. Features.
(5) 0.5 <f _{I 2} / f _{I 1} <0.9
(6) 11 <(V _{I 3} + V _{I 6} ) / 2− (V _{I 4} + V _{I 5} + V _{I 7} ) / 3
However,
f _{I 1} : Focal length of the negative lens disposed closest to the magnification side in the first lens group f _{I 2} : Focal length V _{I 3 of the} negative lens disposed on the second lens from the magnification side in the first lens group Abbe number V _{I 4} of the negative lens arranged in the third lens from the magnification side in one lens group: Abbe number V _{I 5 of the} positive lens arranged in the fourth lens from the magnification side in the first lens group: First lens Abbe number V _{I 6} of the positive lens arranged in the fifth lens from the magnifying side in the group: Abbe number V _{I 7 of} negative lens arranged in the sixth lens from the magnifying side in the first lens group: In the first lens group Abbe number of positive lens arranged on the most reduction side

The invention according to claim 3 is the wide-angle lens according to claim 1,
2. The wide-angle lens according to claim 1, wherein the second lens group is configured by arranging one positive lens in order from the magnification side, or by arranging two positive lenses, The following conditional expression (7) is satisfied with respect to the combined focal length of the second lens group.
(7) 0.2 <f / f II <0.5
However,
f _II : Composite focal length of the second lens group

The invention according to claim 4 is the wide-angle lens according to claim 1,
The third lens group includes six lenses of a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens in order from the magnification side, and is arranged as the fourth lens from the magnification side. The following conditional expression (8) is satisfied with respect to the focal length of the negative lens, and the following conditional expression (9) is satisfied with respect to the power of the surface on the reduction side of the positive lens that constitutes the third lens group on the most reduction side. And the following conditional expression (10) is satisfied with respect to the dispersion characteristics of the glass material used for each of the six lenses used in the third group.
(8) 0.5 <f / fIII ₄ <−0.3
(9) −0.5 <f / r _{III 11} <−0.3
(10) 30 <( _VIII1 + _VIII3 + _VIII5 + _VIII6 ) / 4- ( _VIII2 + _VIII4 ) / 2
However,
f _{III 4} : Focal length r _{III of the} negative lens arranged fourth from the magnification side of the third lens group ₁₁ : Radius of curvature V _III of the reduction side surface of the lens arranged closest to the reduction surface side of the third lens group ₁ : Abbe number V _{III of the} positive lens arranged closest to the enlargement side in the third lens group ₂ : Abbe number V _{III 3 of the} positive lens arranged second from the enlargement side in the third lens group ₃ : Third lens Abbe number V _{III 4} of the negative lens arranged on the third lens from the magnifying side in the group: Abbe number V _{III 5 of} positive lens arranged on the fourth lens from the magnifying side in the third lens group: In the third lens group Abbe number of positive lens arranged on the fifth lens from the magnification side V _{III 6} : Abbe number of positive lens arranged closest to the reduction side in the third lens group

  According to a fifth aspect of the present invention, in the projector device, the wide-angle lens according to any one of the first to fourth aspects is mounted.

Claims (5)

In order from the magnifying side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a third lens group having a positive refractive power as a whole, and a positive refractive power as a whole The first lens group includes, in order from the magnifying side, a lens having a meniscus shape convex to the magnifying side and having negative refractive power (hereinafter, negative lens), negative lens, negative lens, positive lens A lens having a refractive power (hereinafter, positive lens), a positive lens, a negative lens, and a positive lens are arranged, and the second lens group includes one positive lens in order from the magnification side. The third lens group includes, in order from the magnification side, a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens. 6 lenses are arranged, and the fourth lens group includes positive lenses. A wide-angle lens that is configured by disposing one,
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 third 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 focusing position:
The following conditional expression (4) is satisfied with respect to the distance on the optical axis from the reduction side surface of the lens arranged closest to the reduction side of the third lens group to the enlargement side surface of the lens arranged in the fourth lens group. A wide-angle lens characterized by that.
(1) -2.2 <f / f I <-0.8
(2) 0.2 <f / f III <0.4
(3) 11.0 <TL / f <17.0
(4) 3.4 <fb / f <4.7
f : Composite focal length of the entire lens system (focused on the magnifying side object distance of 830 mm from the most magnifying side of the first lens group)
f _I : Synthetic focal length of the first lens group f _III : Synthetic focal length of the third lens group TL: On the optical axis from the magnifying side of the lens arranged closest to the magnifying side in the first lens group to the in-focus position Distance (focused on the magnifying object distance of 830 mm from the most magnifying side of the first lens group)
fb: Distance on the optical axis between the reduction side surface of the lens arranged closest to the reduction side in the third lens group and the enlargement side surface of the lens arranged in the fourth lens group (enlargement from the most enlargement side surface of the first lens group) Focused on side object distance 830mm) The first lens group includes, in order from the magnifying side, a meniscus lens convex to the magnifying side (hereinafter referred to as negative lens), a negative lens, a negative lens, and a lens having positive refracting power (hereinafter referred to as positive lens). ), A positive lens, a negative lens, and a positive lens, and the focal length of the negative lens arranged on the most magnifying side in the first lens group, and from the magnifying side on the first lens group. The following conditional expression (5) is satisfied with respect to the focal length of the negative lens disposed on the second lens, and from the negative lens disposed on the third lens from the magnification side of the first lens group, the first lens group 2. The wide angle according to claim 1, wherein the following conditional expression (6) is satisfied with respect to the dispersion characteristics of the glass material used for each of the five lenses constituting the positive lens arranged on the most reduction side: lens.
(5) 0.5 <f _{I 2} / f _{I 1} <0.9
(6) 11 <(V _{I 3} + V _{I 6} ) / 2− (V _{I 4} + V _{I 5} + V _{I 7} ) / 3
However,
f _{I 1} : Focal length of the negative lens disposed closest to the magnification side in the first lens group f _{I 2} : Focal length V _{I 3 of the} negative lens disposed on the second lens from the magnification side in the first lens group Abbe number V _{I 4} of the negative lens arranged in the third lens from the magnification side in one lens group: Abbe number V _{I 5 of the} positive lens arranged in the fourth lens from the magnification side in the first lens group: First lens Abbe number V _{I 6} of the positive lens arranged in the fifth lens from the magnifying side in the group: Abbe number V _{I 7 of} negative lens arranged in the sixth lens from the magnifying side in the first lens group: In the first lens group Abbe number of positive lens arranged on the most reduction side The second lens group is configured by arranging one positive lens in order from the magnification side, or by arranging two positive lenses, and the combined focal length of the second lens group 2. The wide angle lens according to claim 1, wherein the following conditional expression (7) is satisfied.
(7) 0.2 <f / f II <0.5
However,
f _II : Composite focal length of the second lens group The third lens group includes six lenses of a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a positive lens in order from the magnification side, and is arranged as the fourth lens from the magnification side. The following conditional expression (8) is satisfied with respect to the focal length of the negative lens, and the following conditional expression (9) is satisfied with respect to the power of the surface on the reduction side of the positive lens that constitutes the third lens group on the most reduction side. The wide angle according to claim 1, wherein the following conditional expression (10) is satisfied with respect to dispersion characteristics of glass materials used for each of the six lenses used in the third group. lens.
(8) 0.5 <f / fIII ₄ <−0.3
(9) −0.5 <f / r _{III 11} <−0.3
(10) 30 <( _VIII1 + _VIII3 + _VIII5 + _VIII6 ) / 4- ( _VIII2 + _VIII4 ) / 2
However,
f _{III 4} : Focal length r _{III of the} negative lens arranged fourth from the magnification side of the third lens group ₁₁ : Radius of curvature V _III of the reduction side surface of the lens arranged closest to the reduction surface side of the third lens group ₁ : Abbe number V _{III of the} positive lens arranged closest to the enlargement side in the third lens group ₂ : Abbe number V _{III 3 of the} positive lens arranged second from the enlargement side in the third lens group ₃ : Third lens Abbe number V _{III 4} of the negative lens arranged on the third lens from the magnifying side in the group: Abbe number V _{III 5 of} positive lens arranged on the fourth lens from the magnifying side in the third lens group: In the third lens group Abbe number of positive lens arranged on the fifth lens from the magnification side V _{III 6} : Abbe number of positive lens arranged closest to the reduction side in the third lens group   A projector device, comprising the wide-angle lens according to any one of claims 1 to 4.

Images