JP5320224B2 - Projection variable focus lens and projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, light-weight, and bright projection type variable focus lens that has a three-group lens configuration, and in particular, satisfactorily corrects various aberrations when varying magnification, and to provide a projection type display device. <P>SOLUTION: The projection type variable focus lens comprising six or seven lenses, includes: a first group G1 having negative refractive power; a second group G2 comprising two positive lenses; and a third group G3 having positive refractive power. When magnification is varied, toward a telephoto end from a wide angle end, the first group G1 moves from a magnifying side to a reducing side, while the second group G2 moves from the reducing side to the magnifying side, and a telecentric configuration is achieved on the reducing side. Also, following three formulae are satisfied: formula (1)-2.0&le;f1/fw&le;-0.5; formula (2)-8.0&le;f1/f2&le;-0.2; and formula (3) 1.0&le;Bf/fw, wherein fw represents the focal distance of the entire system at the wide angle end, f1 represents the focal distance of the first group, f2 represents the focal distance of the second group, and Bf represents back focus. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a variable focus lens having six or seven lenses mounted on a projection display device or the like and a projection display device including the variable focus lens, and more particularly to a transmissive or reflective liquid crystal display device or DMD. (Digital / Micromirror Device) The present invention relates to a small projection variable focus lens and a projection display device for enlarging and projecting a light beam carrying image information from a light valve such as a display device on a screen.

  In recent years, projection display devices using light valves such as liquid crystal display devices and DMD display devices have become widespread, but the projection lenses mounted on them are of higher performance, brighter, smaller and lighter. Is strongly desired.

  As zoom lenses having a three-group configuration for projection that satisfy these requirements to some extent, for example, those described in Patent Documents 1 and 2 are known.

Japanese Patent Laid-Open No. 10-133110 JP 2007-256711 A

  However, the one described in Patent Document 1 has a problem that the F value at the wide-angle end is not always as bright as 3.0, and the variation in spherical aberration at the time of zooming is too large. Furthermore, the number of lenses is as large as about 12, and from the viewpoint of miniaturization and weight reduction, the requirement is not satisfactorily satisfied.

  On the other hand, in Patent Document 2, although the F-number is improved to 2.4, there is a demand from the viewpoint of a small size and light weight because the diameter of the constituent lenses of the moving group is large and the number of lenses in the moving group is large. Is not necessarily satisfied.

  The present invention provides a projection variable focus lens and a projection display device that have a three-group lens configuration, can be reduced in size and weight, are bright, and can favorably correct various aberrations particularly during zooming. It is intended.

The first projection variable focus lens of the present invention includes:
In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
Furthermore, the following conditional expression is satisfied.
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
1.0 ≦ f3 / fw ≦ 11.0 (4)
here,
fw: focal length of entire system at wide-angle end f1: focal length of the first lens group f2: focal length of the second lens group Bf: back focus
f3: focal length of the third lens unit
The second projection variable focus lens of the present invention is
In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
The first lens group is composed of one or two lenses,
Furthermore, the following conditional expression is satisfied.
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
here,
fw: Total focal length at wide-angle end
f1: focal length of the first lens group
f2: focal length of the second lens group
Bf: Back focus
The third projection variable focus lens of the present invention is
In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
The third lens group is composed of three lenses in order from the magnification side: a negative lens having a concave surface on the reduction side, a positive lens having a convex surface on the reduction side, and a positive lens;
Furthermore, the following conditional expression is satisfied.
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
here,
fw: Total focal length at wide-angle end
f1: focal length of the first lens group
f2: focal length of the second lens group
Bf: Back focus

  Further, it is preferable that the first lens group has an aspheric lens having at least one aspheric surface.

  Further, it is preferable that the third lens group moves during zooming.

  The projection display device of the present invention includes a light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, and any one of the projection variable focus lenses described above. The light beam is modulated by the light valve and projected onto the screen by the projection variable focus lens.

  Here, the “variable focus lens” includes a varifocal lens and a zoom lens. Here, unlike a zoom lens, a varifocal lens is a lens that adjusts the focus shift caused by focusing when the conjugate length changes due to zooming.

  The “enlarged side” means the projected side (screen side), and the screen side is also referred to as the enlarged side for convenience when performing reduced projection. On the other hand, the “reduction side” means the original image display area side (light valve side), and the light valve side is also referred to as the reduction side for the sake of convenience in the case of reduced projection.

  According to the projection variable focus lens of the present invention, the first lens unit on the most enlargement side is set to be negative so that the lens unit having a negative refractive power is preceded. Corners and long back focus can be secured.

  On the other hand, at the time of zooming, the positive second lens group is moved from the reduction side to the enlargement side along the optical axis in accordance with the movement from the wide-angle end to the telephoto end. In addition to the function as a correction group, the lens can have a function as a zooming group, and can suppress aberration fluctuations (especially astigmatism and curvature of field) throughout the zooming range. It is possible to construct a variable focus lens for projection with high performance.

  That is, since the first lens group is negative, both on-axis and off-axis light rays enter the second lens group at a high position. By making the second lens group positive, it is possible to have an effect of largely correcting aberrations such as astigmatism with respect to off-axis rays, but in the case of a variable focus lens, this large aberration correction effect is obtained. On the contrary, it becomes a defect, and the fluctuation of aberration (particularly astigmatism) accompanying the lens movement during zooming becomes large. Therefore, in the projection variable focus lens of the present invention, the second lens unit moves from the reduction side to the enlargement side as it goes from the wide-angle end to the telephoto end in order to suppress fluctuations in aberrations during zooming. Thus, during zooming, the height of off-axis rays incident on the second lens group can be kept at a level that does not change so much, so that aberration correction to off-axis aberrations such as astigmatism is performed. It is possible to always demonstrate the effect. At the same time, the magnitude of astigmatism itself can be reduced.

  Moreover, under the lens configuration as described above, by satisfying the conditional expression (1), aberrations such as curvature of field can be corrected well, and downsizing of the lens system can be promoted. . Further, by satisfying the conditional expression (2), it is possible to promote a reduction in the diameter of the front lens and correct aberrations such as field curvature. Furthermore, when the conditional expression (3) is satisfied, a color composition unit such as a color composition prism can be inserted on the reduction side of the lens system.

  In addition, the projection display device of the present invention uses the projection variable focus lens of the present invention, so that various aberrations including astigmatism are well maintained, and cost reduction and weight reduction are promoted. can do.

It is a figure showing the structure of the projection variable focus lens which concerns on Example 1 of this invention. It is a figure showing the structure of the projection variable focus lens which concerns on Example 2 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 3 of this invention. It is a figure showing the structure of the projection variable focus lens which concerns on Example 4 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 5 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 6 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 7 of this invention. It is a figure showing the structure of the projection variable focus lens which concerns on Example 8 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 9 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 10 of this invention. It is a figure showing the structure of the projection variable focus lens which concerns on Example 11 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 12 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 13 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 14 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 15 of this invention. It is a figure showing the structure of the projection type variable focus lens which concerns on Example 16 of this invention. FIG. 5 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 1; FIG. 6 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 2. FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 3; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 4; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 5; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 6; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 7; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 8; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 9; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 10; FIG. 10 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 11; FIG. 14 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 12; FIG. 14 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 13; FIG. 20 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 14; FIG. 16 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 15; FIG. 20 is a diagram illustrating all aberrations of the projection variable focus lens according to Example 16; It is a figure showing the schematic structure of the principal part of the projection type display apparatus of this invention.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the projection variable focus lens according to the embodiment of the present invention (represented by the one in Example 1) is composed of six lenses (Examples 1 to 6, 13, 14) or 7 A first lens group G1 composed of a single lens (Examples 7 to 12, 15, 16) and having a negative refractive power, a second lens group G2 composed of two positive lenses, and a third lens having a positive refractive power The group G3 is arranged, and at the time of zooming, the first lens group G1 moves from the enlargement side to the reduction side while the second lens group G2 moves from the reduction side to the enlargement side as it goes from the wide-angle end to the telephoto end. However, the reduction side has a telecentric configuration.

  Further, as shown in FIG. 1 and the like, a glass block 2 mainly including a color synthesizing prism and an image display surface 1 of a light valve such as three or more liquid crystal display panels are disposed at the rear stage of the lens system. However, in the so-called single plate type using one light valve, the color synthesis prism is not required.

  Further, for example, as shown in FIG. 1, the mask 3 can be arranged in the second lens group G2 or at other positions.

  In addition, the “mask” in the present specification has a function of blocking a part of the upper side light or the lower side light of the off-axis light. Such a light shielding effect can maintain the balance between the upper and lower rays of off-axis rays, and can prevent the occurrence of color unevenness.

  The mask can also be an aperture stop that limits the upper and lower rays of off-axis rays and defines the brightness.

  During focusing, one lens group, for example, the first lens group G1 (the first lens group G1 in the following embodiments) is moved along the optical axis Z.

  As described above, according to the projection variable focus lens of the present embodiment, the widest angle of view and the long back focus can be easily secured by setting the first lens group G1 (first lens L1) closest to the enlargement side to be negative. To be able to.

  On the other hand, when zooming from the wide-angle end toward the telephoto end, the positive second lens group G2 is moved from the reduction side to the enlargement side along the optical axis, and thereby the second lens group G2 is moved. In addition to the function as a correction group, the lens can have a function as a zooming group, and can suppress fluctuations in aberrations such as astigmatism and curvature of field in the entire zooming range. It is possible to construct a variable focus lens for projection with high performance.

  That is, the second lens group G2 is moved from the reduction side to the enlargement side from the wide-angle end to the telephoto end, and the height of off-axis rays incident on the second lens group G2 does not change much during zooming. Since the height is maintained, the effect of suppressing aberration fluctuations against off-axis aberrations such as astigmatism can always be exhibited. At the same time, astigmatism itself can be reduced.

  The total number of lenses configured as described above is six or seven, and such a small number of lenses can be configured as a zoom lens, but by using a so-called varifocal lens, Can be easily configured. In this case, it is possible to eliminate the restriction on the coordinated movement of the lens group at the time of zooming, so that the aberration fluctuation at the time of zooming can be greatly improved.

  Here, the “variable focus lens” is a concept that includes both a so-called varifocal lens and a zoom lens. Among them, the “varifocal lens” is a focus lens that is generated when the conjugate length changes during zooming. A focusing operation corresponding to the deviation is required. Even when there are two moving groups at the time of zooming, the two moving groups move independently of each other, so that a complicated lens driving mechanism such as a cam mechanism for linking the moving lens groups is unnecessary. It is.

  Compared to the “vari-focal lens”, the “zoom lens” is adjusted so that the conjugate length is constant at the time of zooming, and a slight deviation of the conjugate length is adjusted by the focusing lens. However, at the time of zooming, two or more moving groups move with each other according to a predetermined rule using a zoom cam mechanism or the like, which is generally disadvantageous in terms of size reduction, weight reduction, and cost reduction. .

In the projection variable focus lens according to this embodiment, it is preferable that the following conditional expressions (1), (2), and (3) are satisfied.
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
here,
fw: Total system focal length at the wide-angle end f1: Focal length of the first lens group G1 f2: Focal length of the second lens group G2 Bf: Back focus

  Here, the technical significance of the conditional expressions (1), (2), and (3) described above will be described.

  Conditional expression (1) described above is an expression for prescribing a range for making the aberration correction favorable and setting the distance of the lens back to an appropriate length. If the lower limit of conditional expression (1) is not reached, the negative refractive power of the first lens group G1 becomes too weak and the lens back becomes too short. As a result, the outer diameter of the first lens group G1 must be increased. It becomes difficult to make it compact. On the other hand, if the upper limit is exceeded, the negative refractive power of the first lens group G1 becomes too strong, and it becomes difficult not only to maintain good off-axis aberrations such as coma and field curvature, but also to the lens back. Becomes too long, leading to an increase in the size of the system.

From such a viewpoint, it is more preferable that the following conditional expression (1 ′) is satisfied instead of the conditional expression (1).
-1.8 ≦ f1 / fw ≦ −0.8 (1 ′)

  Conditional expression (2) described above defines the ratio between the focal length of the first lens group G1 and the focal length of the second lens group G2. When the lower limit of the conditional expression (2) is exceeded, The distance between the first lens group G1 and the second lens group G2 must be increased, and the front lens diameter is increased. On the other hand, if the upper limit is exceeded, the curvature of field becomes too large.

From such a viewpoint, it is more preferable to satisfy the following conditional expression (2 ′) instead of the conditional expression (2).
−7.0 ≦ f1 / f2 ≦ −0.4 (2 ′)

  The conditional expression (3) described above is an expression that defines the size of the back focus.

  If the lower limit of conditional expression (3) is not reached, it will be difficult to insert a color synthesis unit such as a color synthesis prism between the lens system and the light valve.

From such a viewpoint, it is more preferable to satisfy the following conditional expression (3 ′) instead of the conditional expression (3).
1.1 ≦ Bf / fw ≦ 2.0 (3 ′)

Furthermore, as an embodiment of the present invention, it is preferable that the third lens group G3 satisfies the following conditional expression (4).
1.0 ≦ f3 / fw ≦ 11.0 (4)
here,
f3: focal length of the third lens group G3

  Conditional expression (4) is a conditional expression for improving the lateral chromatic aberration and realizing telecentricity. That is, below the lower limit, the refractive power of the third lens group G3 becomes too strong, the amount of chromatic aberration of magnification becomes too large, and it becomes difficult to satisfactorily correct the chromatic aberration of magnification with other lens groups. On the other hand, if the upper limit is exceeded, the refractive power of the third lens group G3 becomes too weak, and it becomes difficult to make the reduction side telecentric.

From such a viewpoint, it is more preferable to satisfy the following conditional expression (4 ′) instead of the conditional expression (4).
2.0 ≦ f3 / fw ≦ 10.0 (4 ′)

  The first lens group G1 is preferably composed of one or two lenses.

  The third lens group G3 is preferably composed of three lenses in order from the enlargement side: a negative lens having a concave surface on the reduction side, a positive lens having a convex surface on the reduction side, and a positive lens. . The third lens group G3 is preferably moved upon zooming.

  Here, the projection variable focus lenses of the following examples are all lenses of the first lens group G1 (the second lens L2 in Example 10, the first lens L1 and the second lens L2 in Examples 4 and 14). In other embodiments, the first lens L1) includes at least one aspherical surface, which can make distortion correction advantageous. In addition, by making at least one surface of the first lens L1 an aspherical surface, it is possible to appropriately correct the aberration for each angle of view. The aspheric shape is represented by the following aspheric expression.

  Next, an example of a projection display device equipped with the above-described projection variable focus lens will be described with reference to FIG. The projection display device shown in FIG. 33 includes transmissive liquid crystal panels 11a to 11c as light valves, and uses the projection variable focus lens 10 according to the above-described embodiment as a projection variable focus lens. Further, an integrator (not shown) such as a fly-eye is disposed between the light source and the dichroic mirror 12, and white light from the light source passes through three illumination light beams (G light, B) via the illumination optical unit. Are incident on the liquid crystal panels 11 a to 11 c corresponding to the light and the R light, respectively, are light-modulated, color-combined by the cross dichroic prism 14, and projected onto a screen (not shown) by the projection variable focus lens 10. This apparatus includes dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color composition, condenser lenses 16a to 16c, and total reflection mirrors 18a to 18c. Since the projection display device of the present embodiment uses the projection variable focus lens according to the present embodiment, it is possible to achieve a reduction in size, weight, and cost, while having a configuration capable of high magnification. Moreover, high optical performance can be maintained.

  Note that the projection variable focus lens of the present invention is not limited to a use mode as a projection variable focus lens of a projection display device using a transmission type liquid crystal display panel, but a reflection type liquid crystal display panel, DMD, or the like. It can also be used as a projection variable focus lens of an apparatus using other light modulation means.

Hereinafter, the projection variable focus lens of the present invention will be further described with reference to specific examples.
<First Example Group>
The first example group includes projection variable focus lenses according to Examples 1 to 6 below, and includes a first lens group G1 including the first lens L1, a second lens L2, and a third lens L3. And the third lens group G3 including the fourth lens L4 to the sixth lens L6, and at the time of zooming, the first lens group G1 and the second lens group G2 are independent of each other. Configured to move.

  The projection variable focus lens according to Example 1 is configured as shown in FIG.

  In other words, in this projection variable focus lens, in order from the magnification side, the first lens group G1 is composed of a first lens L1 composed of a double-sided aspheric negative meniscus lens (on the axis) with the concave surface facing the reduction side. The second lens group G2 has a second lens L2 made of a biconvex lens, a mask 3 (which can be used as an aperture stop instead of the mask: the same in the following embodiments), and a convex surface facing the reduction side. It consists of the 3rd lens L3 which consists of a double-sided aspherical positive meniscus lens (on-axis). The third lens group G3 includes a fourth lens L4 made of a biconcave lens, a fifth lens L5 made of a positive meniscus lens having a convex surface directed toward the reduction side, and a planoconvex lens made up of a plane facing the reduction side. It consists of a lens L6.

  Further, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide angle end to the telephoto end, and the second lens group G2 moves to the enlargement side along the optical axis Z. Move to.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The radius of curvature R of each lens surface in Example 1 (standardized with the focal length at the wide-angle end of the entire lens system as 1.00; the same in the following tables), the center thickness of each lens, and the distance between the lenses The upper part of Table 1 shows the air spacing D (standardized in the same manner as the radius of curvature R described above; the same in the following tables), the refractive index Nd and the Abbe number νd of each lens at the d-line. In Table 1 and Tables 2 to 16 to be described later, the numbers corresponding to the symbols R, D, Nd, and νd are sequentially increased from the enlargement side, and an asterisk (*) is added to the right side of the surface number. The finished surface is an aspherical surface. In the middle of Table 1, the variable interval 1 (the interval between the first lens group G1 and the second lens group G2 (hereinafter referred to as the following) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) is shown. The same) in each table)), and the variable interval 2 (the interval between the second lens group G2 and the third lens group G3 (same in the following tables)). The values of the constants K and A3 to A16 corresponding to are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in the first embodiment.

  FIG. 17 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 1. It is. In FIG. 17 and the following FIGS. 18 to 32, the spherical aberration diagrams show the aberrations for the light of the d-line, F-line, and C-line, and the astigmatism diagrams show the sagittal image plane and tangential. Aberrations for the image plane are shown. In each chromatic aberration diagram, aberrations for the F-line and C-line light with respect to the d-line light are shown.

  As apparent from FIG. 17, according to the projection variable focus lens of Example 1, the angle of view 2ω at the wide angle end is as wide as 56.4 degrees, the F value is as bright as 2.20, and each aberration is Corrected well.

  Moreover, as shown in Table 17, according to the projection variable focus lens of Example 1, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 2 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the first embodiment, except that the mask 3a is disposed in the first lens group G1 and the mask 3b is disposed in the second lens group G2. And the fourth lens L4 and the fifth lens L5 are cemented with each other to form a cemented lens.

  Similarly to the first embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the shift from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 2 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 2.

  The middle row of Table 2 shows variable intervals 1 and 2 at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 2.

  FIG. 18 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 2. It is.

  As is clear from FIG. 18, according to the projection variable focus lens of Example 2, the angle of view 2ω at the wide angle end is 56.2 degrees and the wide angle is bright, the F value is 2.20, and each aberration is large. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 2, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 3 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the first embodiment, except that the third lens L3 is a biconvex lens composed of a spherical lens, and the fifth lens L5 is a double-sided aspheric surface. They are different in that they are composed of a positive meniscus lens (on the axis) with the convex surface facing the reduction side, and the sixth lens L6 is composed of a biconvex lens.

  Similarly to the first embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the shift from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 3 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 3.

  The middle row of Table 3 shows variable intervals 1 and 2 at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 3.

  FIG. 19 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 3. It is.

  As is apparent from FIG. 19, according to the projection variable focus lens of Example 3, the angle of view 2ω at the wide angle end is as wide as 56.0 degrees, the F value is 2.20, and the respective aberrations are bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 3, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 4 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the first embodiment, but the second lens L2 is a double-sided aspherical positive meniscus lens (on the axis) with the convex surface facing the reduction side. This is different in that the third lens L3 is made of a biconvex lens composed of a spherical lens, and the sixth lens L6 is made of a biconvex lens.

  Similarly to the first embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the shift from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 4 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 4.

  The middle part of Table 4 shows the variable interval 1 and variable interval 2 at each of the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 4.

  FIG. 20 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele) of the projection variable focus lens of Example 4. It is.

  As can be seen from FIG. 20, according to the projection variable focus lens of Example 4, the angle of view 2ω at the wide angle end is as wide as 44.2 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 4, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 5 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the first embodiment, except that the third lens L3 is a biconvex lens composed of a spherical lens, and the fifth lens L5 is convex on the reduction side. And the sixth lens L6 is different from the biconvex lens.

  Similarly to the first embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the shift from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 5 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 5.

  The middle row of Table 5 shows variable intervals 1 and 2 at each of the wide angle end (wide), intermediate position (middle), and telephoto end (tele). The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 5.

  FIG. 21 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 5. It is.

  As is apparent from FIG. 21, according to the projection variable focus lens of Example 5, the angle of view 2ω at the wide angle end is as wide as 43.2 degrees, the F value is 2.20, and each aberration is as bright as possible. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 5, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 6 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the first embodiment, but the first lens L1 is a negative meniscus compound aspherical lens (a glass lens having a concave surface facing the reduction side). The reduction-side surface is provided with a resin film, and the most reduction-side surface is an aspheric surface (the same applies to the first lens L1 of Example 12). The third lens L3 is a biconvex lens. And the sixth lens L6 is different from the biconvex lens.

  Similarly to the first embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the shift from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 6 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 6.

  The middle row of Table 6 shows the variable intervals 1 and 2 at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 6.

  FIG. 22 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele) of the projection variable focus lens of Example 6. It is.

  As is apparent from FIG. 22, according to the projection variable focus lens of Example 6, the angle of view 2ω at the wide angle end is as wide as 44.0 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 6, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

<Second Example Group>
The second example group includes projection variable focus lenses according to Examples 7 to 12 below, and includes a first lens group G1 including a first lens L1 and a second lens L2, and a third lens L3. And a second lens group G2 composed of the fourth lens L4 and a third lens group G3 composed of the fifth lens L5 to the seventh lens L7. At the time of zooming, the first lens group G1 and the second lens group G2 Are configured to move independently of each other.

  The projection variable focus lens according to Example 7 is configured as shown in FIG.

  That is, the projection variable focus lens will be described in order from the enlargement side. First, the first lens group G1 is composed of a first lens L1 made of a negative double-sided aspheric lens having low power and a second lens L2 made of a biconcave lens. Become. The second lens group G2 includes a third lens L3 made of a biconvex lens and a fourth lens L4 made of a biconvex lens (on the axis) having a double-sided aspheric surface. The third lens group G3 includes a fifth lens L5 made of a biconcave lens, a sixth lens L6 made of a positive meniscus lens having a convex surface facing the reduction side, and a seventh lens L7 made of a biconvex lens.

  Further, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide angle end to the telephoto end, and the second lens group G2 moves to the enlargement side along the optical axis Z. Move to.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The radius of curvature R of each lens surface in Example 7 (standardized with the focal length at the wide-angle end of the entire lens system as 1.00; the same in the following tables), the center thickness of each lens, and the distance between the lenses The upper part of Table 7 shows the air spacing D (standardized in the same manner as the curvature radius R described above; the same in the following tables), the refractive index Nd and the Abbe number νd of each lens at the d-line.

  The middle row of Table 7 shows the variable intervals 1 and 2 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 7.

  FIG. 23 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 7. It is.

  As apparent from FIG. 23, according to the projection variable focus lens of Example 7, the angle of view 2ω at the wide-angle end is as wide as 56.8 degrees, the F value is as bright as 2.20, and each aberration is Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 7, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 8 is configured as shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the seventh embodiment, except that the first lens L1 is composed of a positive double-sided aspherical lens with low power, and two masks 3a and 3b (masks). (The same is true in the following embodiments) is arranged in the second lens group G2, and the seventh lens L7 is a plano-convex lens having a convex surface facing the enlargement side. Is different.

  Similarly to the seventh embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 8 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 8.

  The middle row of Table 8 shows variable intervals 1 and 2 at each of the wide angle end (wide), intermediate position (middle), and telephoto end (tele). The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 8.

  FIG. 24 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), intermediate position (middle), and telephoto end (tele) of the projection variable focus lens of Example 8. It is.

  As is apparent from FIG. 24, according to the projection variable focus lens of Example 8, the angle of view 2ω at the wide angle end is as wide as 57.4 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 8, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 9 has the structure shown in FIG.

  In other words, the projection variable focus lens has substantially the same configuration as that of Example 8, but the sixth lens L6 is a biconvex lens and is cemented with the fifth lens L5 to form a cemented lens. This is different in that the seventh lens L7 is a positive meniscus lens having a convex surface on the enlargement side.

  Similarly to the seventh embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 9 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 9.

  The middle row of Table 9 shows the variable intervals 1 and 2 at each of the wide-angle end (wide), intermediate position (middle), and telephoto end (tele). The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 9.

  FIG. 25 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 9. It is.

  As is apparent from FIG. 25, according to the projection variable focus lens of Example 9, the angle of view 2ω at the wide angle end is as wide as 57.4 degrees, the F value is as bright as 2.00, and each aberration is Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 9, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 10 has the structure shown in FIG.

  That is, the projection variable focus lens has a configuration similar to that of the seventh embodiment, except that the first lens L1 is a biconcave lens and the second lens L2 is a double-sided aspheric lens with low power, and The difference is that one mask 3 is arranged in the second lens group G2.

  Similarly to the seventh embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 10 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 10.

  The middle row of Table 10 shows the variable intervals 1 and 2 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 10.

  FIG. 26 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 10. It is.

  As is apparent from FIG. 26, according to the projection variable focus lens of Example 10, the angle of view 2ω at the wide angle end is as wide as 57.2 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 10, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 11 has the structure shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the seventh embodiment, except that the fourth lens L4 is a biconvex lens formed of a spherical lens, and one mask 3 is the second lens. It is different in that it is arranged in the group G2.

  Similarly to the seventh embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  Table 11 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line, and the Abbe number νd in Example 11.

  The middle part of Table 11 shows the variable interval 1 and variable interval 2 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 11.

  FIG. 27 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 11. It is.

  As is apparent from FIG. 27, according to the projection variable focus lens of Example 11, the field angle 2ω at the wide angle end is as wide as 56.4 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Moreover, as shown in Table 17, according to the projection variable focus lens of Example 11, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 12 has the structure shown in FIG.

  In other words, the projection variable focus lens has substantially the same configuration as that of the fifth embodiment, but the first lens L1 is a negative meniscus compound aspherical lens having a concave surface facing the reduction side (glass lens). The surface of the reduction side is provided with a resin film, the surface of the reduction side being the most aspherical surface), and the point of the second lens L2 being a negative meniscus lens having a convex surface facing the enlargement side And the sixth lens L6 is a biconvex lens.

  Similarly to the seventh embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 Moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 12 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 12.

  The middle row of Table 12 shows variable intervals 1 and 2 at each of the wide-angle end (wide), intermediate position (middle), and telephoto end (tele). The values of the constants K and A3 to A16 corresponding to the spherical surface are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 12.

  FIG. 28 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 12. It is.

  As is clear from FIG. 28, according to the projection variable focus lens of Example 12, the angle of view 2ω at the wide angle end is 56.6 degrees, the wide angle is as bright as 2.20, and each aberration is Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 12, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

<Third Example Group>
The third example group includes projection variable focus lenses according to Examples 13 and 14 below, and includes a first lens group G1 including the first lens L1, a second lens L2, and a third lens L3. And a third lens group G3 consisting of a fourth lens L4 to a sixth lens L6. At the time of zooming, the first lens group G1, the second lens group G2, and the third lens group The three lens groups G3 are configured to move independently of each other.

  The projection variable focus lens according to Example 13 has the structure shown in FIG.

  In other words, in this projection variable focus lens, in order from the magnification side, the first lens group G1 is composed of a first lens L1 composed of a double-sided aspheric negative meniscus lens (on the axis) with the concave surface facing the reduction side. The second lens group G2 includes a second lens L2 made of a biconvex lens, a mask 3, and a third lens L3 made of a double-sided aspheric positive meniscus lens (on the axis) with the convex surface facing the reduction side. The third lens group G3 includes a fourth lens L4 made of a biconcave lens, a fifth lens L5 made of a biconvex lens, and a sixth lens L6 made of a biconvex lens.

  Further, at the time of zooming, with the transition from the wide angle end to the telephoto end, the first lens group G1 moves to the reduction side along the optical axis Z, and the second lens group G2 moves to the enlargement side along the optical axis Z. While moving, the third lens group G3 moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 13 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 13.

  In the middle of Table 13, the variable interval 1, the variable interval 2 and the variable interval 3 (the third lens group G3 and the glass block 2) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) are shown. (Same in the following tables), and the lower part of Table 13 shows the values of the constants K and A3 to A16 corresponding to the respective aspheric surfaces.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 13.

  FIG. 29 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 13. It is.

  As is apparent from FIG. 29, according to the projection variable focus lens of Example 13, the angle of view 2ω at the wide-angle end is as wide as 57.0 degrees, the F value is 2.20, and each aberration is bright. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 13, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 14 has the structure shown in FIG.

  In other words, the projection variable focus lens has substantially the same configuration as that of Example 13, except that the second lens L2 is a double-sided aspheric positive meniscus lens (on the axis) with the convex surface facing the reduction side. This is different in that the third lens L3 is a biconvex lens composed of a spherical lens and the fifth lens L5 is a positive meniscus lens having a convex surface facing the reduction side. A mask is not arranged in the optical path.

  As in the thirteenth embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 moves. While moving to the magnification side along the optical axis Z, the third lens group G3 moves to the magnification side along the optical axis Z.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 14 shows the curvature radius R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 14.

  The middle part of Table 14 shows the variable interval 1, variable interval 2 and variable interval 3 at the wide-angle end (wide), intermediate position (middle) and telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the respective aspheric surfaces are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 14.

  FIG. 30 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 14. It is.

  As apparent from FIG. 30, according to the projection variable focus lens of Example 14, the angle of view 2ω at the wide-angle end is as wide as 44.2 degrees, the F value is 2.20, and each aberration is as bright as possible. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 14, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

<Fourth Example Group>
The fourth example group includes projection variable focus lenses according to Examples 15 and 16 below, and includes a first lens group G1 including a first lens L1 and a second lens L2, and a third lens L3. And a second lens group G2 including the fourth lens L4, and a third lens group G3 including the fifth lens L5, the sixth lens L6, and the seventh lens L7. The second lens group G2 and the third lens group G3 are configured to move independently of each other.

  The projection variable focus lens according to Example 15 has the structure shown in FIG.

  That is, this projection variable focus lens will be described in order from the magnification side. First, the first lens group G1 is composed of a first lens L1 made of a double-sided aspherical lens having a low power and a second lens L2 made of a biconcave lens. The second lens group G2 includes a third lens L3 made of a biconvex lens, a mask 3, and a fourth lens L4 made of a biconvex lens (on the axis) having a double-sided aspheric surface. The third lens group G3 includes a fifth lens L5 made of a biconcave lens, a sixth lens L6 made of a positive meniscus lens having a convex surface facing the reduction side, and a seventh lens L7 made of a biconvex lens.

  Further, at the time of zooming, with the transition from the wide angle end to the telephoto end, the first lens group G1 moves to the reduction side along the optical axis Z, and the second lens group G2 moves to the enlargement side along the optical axis Z. While moving, the third lens group G3 moves along the optical axis Z to the enlargement side.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 15 shows the curvature radius R of each lens surface, the center thickness of each lens and the air space D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 15.

  The middle part of Table 15 shows the variable interval 1, variable interval 2 and variable interval 3 at the wide-angle end (wide), the intermediate position (middle) and the telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the respective aspheric surfaces are shown.

  Table 17 shows numerical values corresponding to the above conditional expressions in Example 15.

  FIG. 31 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 15. It is.

  As is apparent from FIG. 31, according to the projection variable focus lens of Example 15, the angle of view 2ω at the wide angle end is as wide as 56.6 degrees, the F value is as bright as 2.00, and each aberration is Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 15, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

  The projection variable focus lens according to Example 16 has the structure shown in FIG.

  That is, the projection variable focus lens has substantially the same configuration as that of the fifteenth embodiment, but differs in that the fourth lens L4 is a biconvex lens formed of a spherical lens.

  Similarly to the fifteenth embodiment, at the time of zooming, the first lens group G1 moves to the reduction side along the optical axis Z along with the transition from the wide-angle end to the telephoto end, and the second lens group G2 moves. While moving to the magnification side along the optical axis Z, the third lens group G3 moves to the magnification side along the optical axis Z.

  Further, focusing is performed by moving the first lens group G1 in the direction of the optical axis Z (the varifocal lens type).

  The upper part of Table 16 shows the radius of curvature R of each lens surface, the center thickness of each lens and the air gap D between each lens, the refractive index Nd of each lens at the d-line and the Abbe number νd in Example 16.

  The middle part of Table 16 shows the variable interval 1, variable interval 2 and variable interval 3 at the wide-angle end (wide), intermediate position (middle) and telephoto end (tele), respectively. The values of the constants K and A3 to A16 corresponding to the respective aspheric surfaces are shown.

  Table 17 shows numerical values corresponding to the conditional expressions in Example 16.

  FIG. 32 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele) of the projection variable focus lens of Example 16. It is.

  As is clear from FIG. 32, according to the projection variable focus lens of Example 16, the angle of view 2ω at the wide angle end is as wide as 56.2 degrees, the F value is 2.10, and each aberration is as bright as possible. Corrected well.

  Further, as shown in Table 17, according to the projection variable focus lens of Example 16, all the conditional expressions (1) to (4) and (1 ′) to (4 ′) are satisfied.

G1 to G3 Lens group L1 to L7 Lens R1 to R18 Radius of curvature of lens surface, etc. D1 to D17 Lens surface interval (lens thickness)
Z Optical axis 1 Image display surface 2 Glass block (including filter part)
3, 3a, 3b Mask (aperture stop)
DESCRIPTION OF SYMBOLS 10 Projection type variable focus lens 11a-c Transmission type liquid crystal panel 12, 13 Dichroic mirror 14 Cross dichroic prism 16a-c Condenser lens 18a-c Total reflection mirror

Claims (6)

In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
Furthermore, the projection variable focus lens characterized by satisfying the following conditional expression:
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
1.0 ≦ f3 / fw ≦ 11.0 (4)
here,
fw: focal length of entire system at wide-angle end f1: focal length of the first lens group f2: focal length of the second lens group Bf: back focus
f3: focal length of the third lens unit In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
The first lens group is composed of one or two lenses,
Furthermore, the projection variable focus lens characterized by satisfying the following conditional expression:
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
here,
fw: focal length of entire system at wide-angle end f1: focal length of the first lens group f2: focal length of the second lens group Bf: back focus In order from the magnification side, a first lens group having negative refractive power, a second lens group consisting of two positive lenses, and a third lens group having positive refractive power are arranged,
At the time of zooming, the first lens group moves from the enlargement side to the reduction side as it moves from the wide-angle end to the telephoto end, while the second lens group moves from the reduction side to the enlargement side,
The reduction side has a telecentric configuration,
The third lens group is composed of three lenses in order from the magnification side: a negative lens having a concave surface on the reduction side, a positive lens having a convex surface on the reduction side, and a positive lens;
Furthermore, the projection variable focus lens characterized by satisfying the following conditional expression:
-2.0 ≤ f1 / fw ≤ -0.5 (1)
−8.0 ≦ f1 / f2 ≦ −0.2 (2)
1.0 ≤ Bf / fw (3)
here,
fw: focal length of entire system at wide-angle end f1: focal length of the first lens group f2: focal length of the second lens group Bf: back focus The projection variable focus lens according to any one of claims 1 to 3, wherein the first lens group includes an aspheric lens having at least one aspheric surface. The third lens group, a projection variable focus lens of any one of claims 1-4, characterized in that moves during zooming. A light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, and a projection variable focus lens according to any one of claims 1 to 5 , wherein the light beam from the light source Is projected on a screen by the projection variable focus lens.

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