JP2011100080A - Projection zoom lens and projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection zoom lens that has a wide angle with a large zoom ratio, ensures a back focus sufficiently long for inserting a composite prism or the like, and at the same time, can reduce, to a large degree, chromatic aberration of magnification in particular, and to provide a projection type display apparatus. <P>SOLUTION: In the projection zoom lens that performs variable power operation by moving two or more lens groups from among a plurality of lens groups, a telecentric system is achieved on a reducing side. Also, the first group G<SB>1</SB>on the most magnifying side has negative refractive power as a whole, and is fixed when power is varied. The first group G<SB>1</SB>includes a negative cemented lens formed by cementing a negative lens, whose concave face faces the reducing side, and a negative meniscus lens, whose concave face faces the reducing side, with each other. Preferably, an aspherical lens is disposed on the magnifying side or reducing side of the cemented lens. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection zoom lens and a projection display device equipped with the projection zoom lens.

  In recent years, projection display devices having a relatively long back focus using various light valves such as a transmissive or reflective liquid crystal display device and a DMD display device have become widespread and have high performance.

  As a projection lens used in the projection display device, a zoom lens that can change the size of an image on the screen is often used, and recently, the ratio of the change is large, that is, the zoom ratio is large. There is a growing demand for zoom lenses.

  In addition, for example, a lens shift function for shifting the center of the projected image upward with respect to the projection display device and a widening function capable of projecting a large image close to the projection display device are required. However, it is necessary to widen the angle of the zoom lens.

  In addition, in an optical system using a plurality of light valves, a space for inserting a synthesis prism for synthesizing light beams of respective colors from each light valve is required, so that a long back focus is required.

  Conventionally, as this type of projection zoom lens, for example, the one described in Patent Document 1 below is known.

JP 2005-106948 A

  However, although the zoom ratio is as large as 1.5 times or more in the one described in Patent Document 1, the angle of view is considered to meet the recent demand for wide angle. Not.

  In recent years, light bulbs have become smaller and pixels have become more precise, and projection zoom lenses have been required to further reduce lateral chromatic aberration. However, the lens described in Patent Document 1 is not sufficient. It is. In particular, lateral chromatic aberration is a major factor that determines image quality. When the lateral chromatic aberration is more than half that of a light valve pixel, the projected image quality is significantly impaired, which may cause practical problems.

  The present invention has been made in view of such circumstances, and for projections that can greatly reduce chromatic aberration of magnification, in particular, while ensuring a sufficiently long back focus for inserting a composite prism or the like with a wide angle and a large zoom ratio. An object of the present invention is to provide a zoom lens and a projection display device.

The first projection zoom lens of the present invention comprises:
In a projection zoom lens that performs zooming operation by moving at least two of the plurality of lens groups,
The reduction side is configured as a telecentric system,
The lens unit on the most enlargement side has a negative refractive power as a whole, and is fixed during zooming. A negative lens with a concave surface on the reduction side and a negative meniscus with a concave surface on the reduction side A negative cemented lens formed by cementing lenses together is provided.

The second projection zoom lens of the present invention is the first projection zoom lens,
The following conditional expression (1) is satisfied.
25 ≦ νd2−νd1 (1)
However,
νd1: Abbe number of the enlargement side lens among the cemented lenses
νd2: Abbe number of the reduction lens among the cemented lenses

The third projection zoom lens of the present invention is the first or second projection zoom lens,
The following conditional expression (2) is satisfied.
0.10 ≦ nd2−nd1 (2)
However,
nd1: Refractive index of the enlarged lens among the cemented lenses
nd2: Refractive index of the reduction lens among the cemented lenses

The fourth projection zoom lens of the present invention is the projection zoom lens according to any one of the first to third projection zoom lenses,
The following conditional expression (3) is satisfied.
1.0 ≦ fc / f1 ≦ 5.0 (3)
However,
fc: focal length of the cemented lens
f1: Focal length of the most magnified lens group

The fifth projection zoom lens of the present invention is the projection zoom lens according to any one of the first to fourth projection zoom lenses,
The most magnified lens group has at least one aspheric lens;
The following conditional expression (4) is satisfied.
4.0 ≦ | fas | / fw (4)
However,
fas: focal length of the aspherical lens
fw: focal length of the entire system at the wide angle end

The sixth projection zoom lens of the present invention is the projection zoom lens according to any one of the first to fifth projection zoom lenses,
The most magnified lens group is composed of four lenses, an aspheric lens, a cemented lens formed by cementing two lenses, and a biconcave lens.

  According to a seventh projection zoom lens of the present invention, in any one of the first to fifth projection zoom lenses, the projection zoom lens is not adjacent to the enlargement side or the reduction side of the cemented lens. A spherical lens is provided.

Further, an eighth projection zoom lens of the present invention is the projection zoom lens according to any one of the first to seventh projection zoom lenses,
In order from the enlargement side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a positive lens A fifth lens group having a refractive power of 6 and a sixth lens group having a positive refractive power,
At the time of zooming, among the six lens groups, four lens groups from the second lens group to the fifth lens group are configured to be movable along the optical axis. .

Further, a ninth projection zoom lens of the present invention is the projection zoom lens according to any one of the first to seventh projection zoom lenses,
In order from the enlargement side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a positive lens A fifth lens group having a refractive power of
At the time of zooming, among the five lens groups, three lens groups from the second lens group to the fourth lens group are configured to be movable along the optical axis. .

  The projection display device according to the present invention includes any one of a light source, a light valve, an illumination optical unit that guides a light beam from the light source to the light valve, and the first to ninth projection zoom lenses. A zoom lens for projection, wherein the reduction side is made telecentric, and the light beam from the light source is modulated by the light valve and projected onto the screen by the projection zoom lens. It is a feature.

  The “enlarged side” means the projected side (screen side), and the screen side is also referred to as the enlarged side for the sake of 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 zoom lens and the projection display apparatus using the same of the present invention, the zoom lens has a wide zoom ratio, a wide zoom ratio, and a sufficiently long back focus for inserting a composite prism, etc. Can be reduced.

  In general, lateral chromatic aberration is easily affected by a lens that passes through a position where off-axis rays are high, and it is possible to effectively correct lateral chromatic aberration by placing a lens with an achromatic action or a cemented lens at this position. It becomes. The projection zoom lens according to the present invention includes a negative cemented lens as a whole in which a negative lens having a concave surface on the reduction side and a negative meniscus lens having a concave surface on the reduction side are cemented to the most magnified lens group. Thus, the cemented lens can be arranged at a position where the off-axis light is high, and the lens arrangement having a great effect of correcting the lateral chromatic aberration can be obtained.

  Further, by using a cemented lens in which negative lenses are cemented together, a large angle of view and a long back focus can be secured relatively easily without impairing the negative refracting power of the most magnified lens group.

FIG. 4 is a diagram illustrating a lens configuration of a projection zoom lens according to Example 1, and a movement position of each lens group at a wide angle end (wide) and a telephoto end (tele). FIG. 6 is a diagram illustrating a lens configuration of a projection zoom lens according to Example 2, and a movement position of each lens group at a wide angle end (wide) and a telephoto end (tele). FIG. 6 is a diagram illustrating a lens configuration of a projection zoom lens according to Example 3, and a movement position of each lens group at a wide-angle end (wide) and a telephoto end (tele). FIG. 10 is a diagram illustrating the lens configuration of a projection zoom lens according to Example 4 and the movement positions of the lens groups at a wide-angle end (wide) and a telephoto end (tele). FIG. 10 is a diagram illustrating the lens configuration of a projection zoom lens according to Example 5 and the movement positions of the lens groups at a wide-angle end (wide) and a telephoto end (tele). FIG. 10 is a diagram illustrating the lens configuration of a projection zoom lens according to Example 6 and the movement positions of the lens groups at a wide-angle end (wide) and a telephoto end (tele). FIG. 10 is a diagram illustrating the lens configuration of a projection zoom lens according to Example 7, and the movement positions of each lens group at a wide-angle end (wide) and a telephoto end (tele). FIG. 10 is a diagram illustrating the lens configuration of a projection zoom lens according to Example 8 and the movement positions of the lens groups at a wide-angle end (wide) and a telephoto end (tele). FIG. 3 is aberration diagrams of the projection zoom lens according to Example 1 at a wide-angle end (wide), an intermediate position (middle), and a telephoto end (tele). FIG. 6 is aberration diagrams of the projection zoom lens according to Example 2 at a wide angle end (wide), an intermediate position (middle), and a telephoto end (tele). FIG. 10 is aberration diagrams of the projection zoom lens according to Example 3 at a wide angle end (wide), an intermediate position (middle), and a telephoto end (tele). FIG. 10 is aberration diagrams of the projection zoom lens according to Example 4 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). FIG. 11 is aberration diagrams of the projection zoom lens according to Example 5 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). FIG. 10 is aberration diagrams of the projection zoom lens according to Example 6 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). FIG. 10 is aberration diagrams of the zoom lens for projection according to Example 7 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). FIG. 10 is aberration diagrams of the projection zoom lens according to Example 8 at the wide-angle end (wide), the intermediate position (middle), and the telephoto end (tele). It is the schematic which shows a part of projection type display apparatus which concerns on this embodiment.

  The zoom lens according to the embodiment of the present invention is used as a projection zoom lens mounted on a projection display device. The gist of the zoom lens is a telecentric system in which the reduction side is configured to change the magnification by moving at least two of the plurality of lens groups. A negative cemented lens in which a negative lens having a concave surface on the reduction side and a negative meniscus lens having a concave surface on the reduction side are cemented with each other. It has.

  FIG. 1 shows the lens configuration at the wide-angle end and the telephoto end of a zoom lens according to Example 1 of the present invention. The embodiment will be described in detail below using this lens as a representative example.

That is, in the example of the present embodiment, in order from the enlargement side, the first lens group G ₁ having a negative refractive power that performs fixed focusing at the time of zooming, and the positive refractive power that moves along the optical axis Z at the time of zooming. A second lens group G ₂ having positive refractive power, a third lens group G ₃ having positive refractive power, a fourth lens group G ₄ having negative refractive power, and a fifth lens group G ₅ having positive refractive power (implementation) Example 8 includes a second lens group G ₂ having a positive refractive power, a third lens group G ₃ having a positive refractive power, a fourth lens group G ₄ having a positive refractive power, and fixed at the time of zooming. A sixth lens group G ₆ having positive refractive power (Example 8 is a fifth lens group G ₅ having positive refractive power) is provided.

Further, the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G _4, and the fifth lens group G ₅ (in Example 8, the second lens group G ₂ , the third lens group Each of G ₃ and the fourth lens group G ₄ includes a lens that moves from the reduction side to the enlargement side at the time of zooming from the wide-angle end to the telephoto end (moved once to the reduction side and then to the enlargement side). (after moving the fourth lens group G ₄ once the reduction side in the embodiments other than 8, is configured to move the enlargement side)) it is preferred.

  Further, the reduction side is configured to be substantially telecentric (telecentric system).

As described above, most magnification side first lens group G ₁ is a lens group is constituted with a negative refractive power as a whole, it has a concave surface facing the negative lens and the reduction side a concave surface facing the reduction side A negative cemented lens formed by cementing negative meniscus lenses to each other is provided.

Thus, most magnification side first lens group G ₁ is a lens group, a negative junction as a whole by joining the negative meniscus lens having a concave surface facing the reduction side and a negative lens having a concave surface directed toward the reduction side Since the lens is arranged, the cemented lens can be arranged at a position where the off-axis light beam becomes high, and the lens arrangement having a great effect of correcting the lateral chromatic aberration can be obtained.

Further, the two lenses constituting the cemented lens, since both are negative lens, without compromising the negative refractive power of the first lens group G _1, relatively easily, a large angle of view and a long back focus Can be secured.

Also, the fourth lens group G ₄ is composed of a negative single lens one with a concave surface facing the magnification side, also the fifth lens group G ₅ is 2 or more positive lenses and two or more negative lenses It is comprised by having.

Further, for example, the first lens group _{G 1} is constituted by four lenses _L 1 ~L _4, the second lens group _{G 2} is constituted by two lenses _L 5, _{L 6,} the third lens group _{G 3} Is composed of two lenses L ₇ and L ₈ , the fourth lens group G ₄ is composed of one lens L ₉ (seven in the eighth embodiment), and the fifth lens group G ₅ is five (implemented). example 8 is constituted by a lens _L 10 _{~L 14} of one), the sixth lens group _{G 6} is two (example 8 constituted by a lens _{L 15, L 16} of 0 sheets).

Focusing, for example, it is performed by moving the entire first lens group G ₁ in the optical axis Z direction.

Incidentally, the sixth lens group G ₆ is a relay lens fixed during zooming, between the image display surface 1 of the sixth lens group G ₆ and the light valve, color combining prism 2 (low-pass (Including various filters such as filters (hereinafter the same)).

The first lens group G ₁ is the most magnification side lens group, an aspherical lens, it is preferable to configure the two lenses by joining formed by a cemented lens, and four lenses of biconcave lens. The first lens group G ₁ by employing such a lens configuration, in a compact arrangement, it is possible to make various aberrations such as lateral chromatic aberration can be favorable.

  It is preferable that an aspheric lens is provided on the enlargement side or reduction side of the cemented lens. By disposing an aspheric lens in this way, aberration correction by the aspheric lens can be performed at a position where the light beam becomes high, and various aberrations such as distortion can be efficiently reduced.

Further, the fifth lens group G _5, from the enlargement side, negative, positive, negative, be comprised of a positive four lens arranged in this order preferably. The fifth lens group having a positive refractive power as a whole is configured to include two or more positive lenses and two or more negative lenses, thereby amplifying the achromatic effect by the combination of the negative lens and the positive lens. In addition, it is possible to achieve an effect of effectively correcting field curvature (field curvature in the sagittal direction) that can be caused by widening the angle.

  Moreover, it is preferable that these four lenses arranged in the order of negative, positive, negative, and positive constitute two sets of negative and positive cemented lenses. By arranging two sets of negative and positive cemented lenses in this way, the achromatic effect and the field curvature correction effect can be improved.

Further, wherein the first lens group G _1, it is preferable to provide at least one aspheric surface. Thus, the light beam diameter increases, will be non-spherical during the first lens group G ₁ is arranged, it is possible to reduce the aberrations efficiently.

The projection zoom lens according to the present embodiment preferably satisfies the following conditional expression (1).
25 ≦ νd2−νd1 (1)
However,
vd1: Abbe number of the expansion-side lens of the cemented lens in the first lens group G ₁
vd2: Abbe number of the reduction side of the lens of the cemented lens in the first lens group G ₁

  Conditional expression (1) is an expression for effectively correcting the chromatic aberration of magnification. If the lower limit is not reached, the chromatic aberration of magnification becomes excessive and correction becomes difficult.

From such a viewpoint, it is more preferable that the following conditional expression (1 ′) is satisfied instead of the conditional expression (1).
30 ≦ νd2−νd1 ≦ 70 (1 ′)

Further, it is more preferable that the following conditional expression (1 ″) is satisfied instead of the conditional expression (1 ′).
34 ≦ νd2−νd1 ≦ 65 (1 ″)

In addition, it is preferable that the projection zoom lens according to the present embodiment satisfies the following conditional expression (2).
0.10 ≦ nd2−nd1 (2)
However,
nd1: refractive index of the magnification side lens of the cemented lens in the first lens group G ₁
nd2: refractive index of the reduction side of the lens of the cemented lens in the first lens group G ₁

  This conditional expression (2) defines the difference between the refractive index of the reduction side lens and the refractive index of the enlargement side lens among the two cemented lenses. As the difference in the refractive index of the lenses becomes smaller, the bending angle of the light beam on the boundary surface between the lenses becomes smaller, and it becomes difficult to satisfactorily correct off-axis aberrations.

From this point of view, it is more preferable that the following conditional expression (2 ′) is satisfied instead of the conditional expression (2).
0.15 ≤ nd2-nd1 (2 ')

In addition, it is preferable that the projection zoom lens according to the present embodiment satisfies the following conditional expression (3).
1.0 ≦ fc / f1 ≦ 5.0 (3)
However,
fc: focal length of the cemented lens in the first lens group _{G 1}
f1: focal length of the first lens group _{G 1}

The conditional expression (3) is an expression for defining the difference between the refractive power and the refractive power of the first lens group G ₁ whole of the cemented lens in the first lens group G _1, when the value exceeds the upper limit, the junction too weak negative refractive power of the lens, it is inevitable to increase the first lens diameter of the lens group G _1, thereby leading to enlargement of the entire lens system. On the other hand, below this lower limit, the negative refractive power of the cemented lens becomes too strong, and it becomes difficult to maintain good off-axis aberrations such as field curvature.

From this point of view, it is more preferable that the following conditional expression (3 ′) is satisfied instead of the conditional expression (3).
1.3 ≦ fc / f1 ≦ 4.0 (3 ′)

In addition, it is preferable that the projection zoom lens according to the present embodiment satisfies the following conditional expression (4).
4.0 ≦ | fas | / fw (4)
However,
fas: focal length of the aspherical lens of the first lens group _{G 1}
fw: focal length of the entire system at the wide angle end

  If the lower limit of conditional expression (4) is not reached, the power of the aspherical lens becomes too strong, and it becomes difficult to use a material such as plastic that has a large variation in aberration due to temperature change. Is disadvantageous.

From this point of view, it is more preferable to configure so as to satisfy the following conditional expression (4a ′) or conditional expression (4b ′) instead of the conditional expression (4).
When an aspheric lens is arranged on the magnification side of the cemented lens 30.0 ≦ | fas | / fw (4a ′)
When an aspherical lens is arranged on the reduction side of the cemented lens 5.0 ≦ | fas | / fw (4b ′)

  Next, an embodiment of a projection display device according to the present invention will be briefly described. FIG. 17 is a schematic configuration diagram of a projection display apparatus according to this embodiment.

  The projection display device shown in FIG. 17 includes transmissive liquid crystal panels 11 a to 11 c as light valves, and uses the projection zoom lens according to the above-described embodiment as the projection lens 10. Further, an integrator (not shown) such as a fly eye is disposed between the light source 20 and the dichroic mirror 12, and white light from the light source 20 passes through three illumination light beams (G light) via an illumination optical unit. , B light, and R light) are respectively incident on the liquid crystal panels 11a to 11c, modulated, and color-combined by the cross dichroic prism 14, and projected onto a screen (not shown) by the projection lens 10. This apparatus includes dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, condenser lenses 16a to 16c, and total reflection mirrors 18a to 18c. Since the projection display device uses the projection zoom lens according to the present embodiment, the projection display device has a wide angle and good image quality of the projected image, and can be a bright and compact projection display device.

  Note that the projection display apparatus shown in FIG. 17 shows an embodiment of the present invention, and various modifications can be made. For example, as a light valve, it is of course possible to use a reflective liquid crystal panel or DMD instead of a transmissive liquid crystal panel.

Hereinafter, the projection zoom lens of the present invention will be further described with reference to specific examples. The numerical data such as R and D shown below are standardized so that the focal length at the wide angle end is 1.
<Example 1>
FIG. 1 shows the movement position and movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens of the first embodiment.

In this lens, the first lens group G ₁ includes, in order from the enlargement side, a first lens L _{1 made} of a double-sided aspheric lens having weak power and a second lens L made of a negative meniscus lens having a concave surface facing the reduction side. and _second and third lens L _3, and a fourth lens L ₄ of a biconcave lens constitute a cemented lens and the second lens L ₂ and third lens L ₃ are bonded to each other.

The second lens group G ₂ includes, in order from the magnification side, a fifth lens L ₅ which is a biconvex lens, a sixth lens L ₆ of a positive meniscus lens having a convex surface facing the magnification side.

The third lens group G ₃ includes, in order from the magnification side, a seventh lens L ₇ made of a biconvex lens made of the eighth lens L ₈ of a negative meniscus lens having a convex surface directed toward the reduction side, the seventh lens L ₇ and the eighth lens L ₈ are joined together to constitute a cemented lens.

The fourth lens group G ₄ includes only the ninth lens L ₉ made of a biconcave lens, the fifth lens group G ₅ includes, in order from the magnification side, a formed of a negative meniscus lens having a convex surface on the magnification side 10 a lens _{L 10,} an eleventh lens _{L 11} of a biconvex lens, a twelfth lens _{L 12} of a biconcave lens, a thirteenth lens _{L 13} of a biconvex lens consists fourteenth lens _{L 14} made of a biconvex lens, a tenth lens _{L 10} eleventh lens _{L 11,} and a twelfth lens _{L 12} thirteenth lens _{L 13} constitute each joined together by a cemented lens.

The sixth lens group G ₆ is composed of, in order from the magnification side, a fifteenth lens L ₁₅ made of a double-sided aspherical lens of a negative meniscus shape with a convex surface on the reduction side, a positive meniscus lens having a convex surface on the reduction side consisting sixteenth lens _{L 16} made.

Both surfaces aspheric shape of the first lens L ₁ and the fifteenth lens L ₁₅ is defined by the aspheric equation shown below.

As shown in FIG. 1, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens group G ₂ ~G ₅ is a mobile unit .

  The reduction side is substantially telecentric.

  The radius of curvature R of each lens surface of the projection zoom lens, the center thickness of each lens and the air spacing between the lenses (hereinafter collectively referred to as the axial top surface spacing) D, the refractive index of each lens at the d-line The values of N and Abbe number ν are shown in Table 1. The numbers in the table represent the order from the enlargement side (the same applies to Tables 3, 5, 7, 9, 11, 13, and 15 below).

  The lower part of Table 1 shows the lens group intervals at the wide-angle end (wide), middle (middle), and telephoto end (tele) (when focusing on infinity: Tables 3, 5, 7, and 9 below). , 11, 13, and 15). Table 2 shows the aspheric coefficients representing the respective aspheric surfaces.

  According to the projection zoom lens of Example 1, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 9 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens according to the first embodiment. In the astigmatism diagrams, aberrations with respect to the sagittal image surface and the tangential image surface are shown (the same applies to FIGS. 10 to 16).

  As is clear from these aberration diagrams, according to the projection zoom lens of Example 1, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.

<Example 2>
FIG. 2 shows the movement position and the movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens according to the second embodiment.

This projection zoom lens basically has a six-group configuration substantially the same as that of the first embodiment, but the second lens L ₂ constituting the first lens group G ₁ has a concave surface on the reduction side. The sixth lens L ₆ constituting the second lens group G ₂ is a biconvex lens, and the fifth lens group G ₅ is arranged on the reduction side in order from the enlargement side. a tenth lens L ₁₀ made from double-sided aspherical lens having a positive meniscus shape with a convex surface, an eleventh lens L ₁₁ of a negative meniscus lens having a convex surface facing the magnification side, a twelfth lens L ₁₂ of a biconvex lens , a thirteenth lens _{L 13} of a biconcave lens, a fourteenth lens _{L 14} which is a biconvex lens, made from the 15 lens _{L 15} which is a biconvex lens, an eleventh lens _{L 11} and the twelfth lens _{L 12} and 13, Len L ₁₃ and fourteenth lens L ₁₄ are each point constituting the bonding has been cemented lens together, respectively different to that of Example 1 in.

Of substantially the same as those described above in Example 1, as shown in FIG. 2, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 3 shows the values of the radius of curvature R of each lens surface of the projection zoom lens, the axial top surface distance D of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 3 shows the lens group intervals at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 4 shows the aspheric coefficients representing the respective aspheric surfaces.

  According to the projection zoom lens of Example 2, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 10 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens according to the second embodiment.

  As is clear from these aberration diagrams, according to the projection zoom lens of Example 2, the amount of variation in various aberrations including spherical aberration and astigmatism accompanying zooming can be extremely reduced, Aberration can be corrected extremely well.

<Example 3>
FIG. 3 shows the movement positions and movement trajectories of the lens groups at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens according to the third embodiment.

This projection zoom lens basically has a six-group configuration substantially the same as that of the first embodiment, but the second lens L ₂ constituting the first lens group G ₁ is a biconcave lens. in point, and the second lens group G ₂ is, at a point consisting of only the fifth lens L ₅ which is a biconvex lens, the fifth lens group G ₅ includes, in order from the enlargement side, a positive having a convex surface facing the reduction side the ninth lens L ₉ made of a double-sided aspherical meniscus lens, a tenth lens L ₁₀ made of a negative meniscus lens having a convex surface on the enlargement side, an eleventh lens L ₁₁ of a biconvex lens, a biconcave lens and the twelfth lens _{L 12,} a thirteenth lens _{L 13} of a biconvex lens consists fourteenth lens _{L 14} made of a biconvex lens, a tenth lens _{L 10} eleventh lens _{L 11,} and the twelfth lens ₁₂ and thirteenth lens L ₁₃ are each point constituting the bonding has been cemented lens together, respectively different to that of Example 1 in.

Of substantially the same as those described above in Example 1, as shown in FIG. 3, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 5 shows values of the radius of curvature R of each lens surface of the projection zoom lens, the axial top surface distance D of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 5 shows the lens group intervals at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 6 shows the aspheric coefficients representing the respective aspheric surfaces.

  According to the projection zoom lens of Example 3, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 11 is an aberration diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens according to the third embodiment.

  As is clear from these aberration diagrams, according to the projection zoom lens of Example 3, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.

<Example 4>
FIG. 4 shows the movement position and the movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens of Example 4.

This projection zoom lens basically has a six-group configuration substantially the same as that of the first embodiment, but the second lens L ₂ constituting the first lens group G ₁ has a concave surface on the reduction side. that it is a plano-concave lens with its, among the lenses constituting the sixth lens group G _6, while the fifteenth lens L ₁₅ is a positive meniscus lens having a convex surface on the reduction side, the sixteenth lens L ₁₆ The second embodiment is different from the first embodiment in that it includes a double-sided aspheric lens.

Of substantially the same as those described above in Example 1, as shown in FIG. 4, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 7 shows the radius of curvature R of each lens surface of this zoom lens for projection, the axial distance D between each lens, and the refractive index N and the Abbe number ν of each lens at the d-line.

  The lower part of Table 7 shows the distance between the lens groups at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 8 shows aspheric coefficients representing the aspheric surfaces.

  According to the projection zoom lens of Example 4, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 12 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens of Example 4.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 4, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.

<Example 5>
FIG. 5 shows the movement positions and movement trajectories of the lens groups at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens of Example 5.

The projection zoom lens is basically has a substantially similar 6-group configuration as that of Example 2, eleventh lens L ₁₁ constituting the fifth lens group G ₅ is composed of a biconcave lens point, and the sixth lens group G ₆ is a point which is only sixteenth lens L ₁₆ made of a plano-convex lens having a convex surface on the enlargement side, respectively different to those described above in example 2 at.

Of substantially the same as those described above in Example 1, as shown in FIG. 5, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 9 shows the values of the radius of curvature R of each lens surface of the projection zoom lens, the axial top surface distance D of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 9 shows the lens group intervals at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 10 shows aspheric coefficients representing the aspheric surfaces.

  According to the projection zoom lens of Example 5, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 13 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens of Example 5.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 5, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.

<Example 6>
FIG. 6 shows the movement position and movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the zoom lens for projection according to the sixth embodiment.

This projection zoom lens basically has a six-group configuration substantially the same as that of the first embodiment, but the second lens L ₂ constituting the first lens group G ₁ is a biconcave lens. at point, also in that the sixth lens L ₆ constituting the second lens group G ₂ is a biconvex lens, a thirteenth lens L ₁₃ constituting the fifth lens group G ₅ is a convex surface facing the reduction side positive in that it consists of a meniscus lens, and the sixth lens group G ₆ is, in that only a fifteenth lens L ₁₅ which is a biconvex lens, differs each to those described above in example 1.

Of substantially the same as those described above in Example 1, as shown in FIG. 6, at the time of zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 11 shows values of the radius of curvature R of each lens surface of this projection zoom lens, the distance D between the axial upper surfaces of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 11 shows the lens group intervals at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 12 shows aspheric coefficients representing the aspheric surfaces.

  According to the projection zoom lens of Example 6, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 14 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the zoom lens for projection of Example 6.

As is apparent from these aberration diagrams, according to the projection zoom lens of Example 6, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.
<Example 7>
FIG. 7 shows the movement position and movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the projection zoom lens of Example 7.

The projection zoom lens is basically has a substantially similar 6-group configuration as that of Example 6, the first lens group G ₁ includes, in order from the magnification side, a concave surface facing the reduction side a first lens L ₁ of a negative meniscus lens, a second lens L ₂ of a negative meniscus lens having a concave surface directed toward the reduction side, and the third lens L ₃ made of a bi-aspherical lens, the biconcave lens 4 consists lens L _4, and the first lens L ₁ and has the second lens L ₂ constitutes a bonded has been cemented lens together, in that the aspherical lens L ₃ are arranged on the reduction side of the cemented lens in addition, a twelfth lens L ₁₂ constituting the fifth lens group G ₅ is one of a biconcave lens, a thirteenth lens L ₁₃ is in that a biconvex lens, respectively different to that of example 6.

Of substantially the same as those described above in Example 1, as shown in FIG. 7, during zooming, the first lens group G ₁ and the sixth lens group G ₆ is a fixed group, the second to fifth lens groups G ₂ ~ G ₅ is a moving group.

  The reduction side is substantially telecentric.

  Table 13 shows the values of the radius of curvature R of each lens surface of the projection zoom lens, the axial top surface distance D of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 13 shows the distance between the lens groups at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 14 shows aspheric coefficients representing the aspheric surfaces.

  According to the projection zoom lens of Example 7, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4a ′) is all satisfied.

  FIG. 15 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens according to the seventh embodiment.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 7, the amount of variation in various aberrations including spherical aberration and astigmatism associated with zooming can be made extremely small. Aberration can be corrected extremely well.

<Example 8>
FIG. 8 shows the movement position and movement locus of each lens group at the wide-angle end (wide) and the telephoto end (tele) in the zoom lens for projection according to the eighth embodiment.

  This projection zoom lens has a five-group configuration unlike the above-described embodiments.

In this lens, the first lens group G ₁ has, in order from the magnification side, a first lens L _{1 made} of a double-sided aspheric lens with weak power, a second lens L _{2 made} of a biconcave lens, and a concave surface facing the reduction side. a third lens L _3, which is a negative meniscus lens, and a fourth lens L ₄ of a biconcave lens, the second lens L ₂ and third lens L ₃ constituting the junction has been cemented lens together .

The second lens group G ₂ includes, in order from the magnification side, a fifth lens L ₅ which is a biconvex lens, a sixth lens L ₆ made of a biconvex lens.

The third lens group G ₃ includes, in order from the magnification side, a seventh lens L ₇ made of a biconvex lens made of the eighth lens L ₈ of a negative meniscus lens having a convex surface directed toward the reduction side, the seventh lens L ₇ and the eighth lens L ₈ are joined together to constitute a cemented lens.

The fourth lens group G ₄ includes, in order from the magnification side, a ninth lens L ₉ of a negative meniscus lens having a concave surface directed toward the magnification side than aspherical lens having a positive meniscus shape with a concave surface facing the magnification side a tenth lens _{L 10} made, an eleventh lens _{L 11} of a negative meniscus lens having a convex surface facing the magnification side, a twelfth lens _{L 12} of a biconvex lens, a thirteenth lens _{L 13} of a biconcave lens, both a fourteenth lens _{L 14} made of a convex lens made of a fifteenth lens _{L 15} made of a biconvex lens, an eleventh lens _{L 11} twelfth lens _{L 12,} and a thirteenth lens _{L 13} fourteenth lens _{L 14} are each mutually They are cemented to form a cemented lens.

The fifth lens group _{G 5} includes only a 16 lens _{L 16} which is a biconvex lens.

Further, as shown in FIG. 8, at the time of zooming, the first lens group G ₁ and the fifth lens group G ₅ is a fixed group, second to fourth lens groups G ₂ ~G ₄ is is a moving group Yes.

  The reduction side is substantially telecentric.

  Table 15 shows values of the radius of curvature R of each lens surface of the projection zoom lens, the distance D between the axial upper surfaces of the lenses, and the refractive index N and Abbe number ν of each lens at the d-line.

  The lower part of Table 15 shows the lens group intervals at the wide-angle end (wide), the middle (middle), and the telephoto end (tele). Table 16 shows aspheric coefficients representing the aspheric surfaces.

  According to the projection zoom lens of Example 8, as shown in Table 17, conditional expressions (1) to (4), (1 ′), (1 ″), (2 ′), (3 ′), (4b ′) is all satisfied.

  FIG. 16 is an aberration diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the wide-angle end (wide), middle (middle), and telephoto end (tele) of the projection zoom lens according to the eighth embodiment.

  As is apparent from these aberration diagrams, according to the projection zoom lens of Example 8, the amount of fluctuation of various aberrations including spherical aberration and astigmatism accompanying zooming can be extremely reduced, Aberration can be corrected extremely well.

  The projection zoom lens according to the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the radius of curvature R and the axial distance D between the lenses can be appropriately changed. Is possible.

  Further, the projection display device of the present invention is not limited to the one having the above-described configuration, and various device configurations including the projection zoom lens of the present invention are possible. As the light valve, for example, a transmissive or reflective liquid crystal display element, or a micro mirror element in which a large number of micro mirrors capable of changing the inclination are formed on a substantially flat surface (for example, manufactured by Texas Instruments). Digital micromirror device) can be used. Also, as the illumination optical system, an appropriate configuration corresponding to the type of light valve can be adopted.

1 image display surface 2 color combining prism 10 for projection zoom lens 11a~11c transmissive liquid crystal panel 12, 13 dichroic mirror 18a~18c total reflection mirror 20 light source G ₁ ~G ₆ lens group L ₁ ~L ₁₇ lens R ₁ to R curvature such as ₃₂ lens surface radius D ₁ to D ₃₁ axial distance Z optical axis

Claims (10)

In a projection zoom lens that performs zooming operation by moving at least two of the plurality of lens groups,
The reduction side is configured as a telecentric system,
The lens unit on the most enlargement side has a negative refractive power as a whole, and is fixed during zooming. A negative lens with a concave surface on the reduction side and a negative meniscus with a concave surface on the reduction side A projection zoom lens comprising a negative cemented lens formed by cementing lenses together. The projection zoom lens according to claim 1, wherein the following conditional expression (1) is satisfied.
25 ≦ νd2−νd1 (1)
However,
νd1: Abbe number of the enlargement side lens among the cemented lenses
νd2: Abbe number of the reduction lens among the cemented lenses 3. The projection zoom lens according to claim 1, wherein the following conditional expression (2) is satisfied.
0.10 ≦ nd2−nd1 (2)
However,
nd1: Refractive index of the enlarged lens among the cemented lenses
nd2: Refractive index of the reduction lens among the cemented lenses The projection zoom lens according to claim 1, wherein the following conditional expression (3) is satisfied.
1.0 ≦ fc / f1 ≦ 5.0 (3)
However,
fc: focal length of the cemented lens
f1: Focal length of the most magnified lens group The most magnified lens group has at least one aspheric lens,
The projection zoom lens according to claim 1, wherein the following conditional expression (4) is satisfied.
4.0 ≦ | fas | / fw (4)
However,
fas: focal length of the aspherical lens
fw: focal length of the entire system at the wide angle end 6. The lens group according to claim 1, wherein the most magnified lens group includes an aspherical lens, a cemented lens obtained by cementing two lenses, and a biconcave lens. A projection zoom lens according to any one of the above. 6. The projection zoom lens according to claim 1, wherein an aspheric lens is disposed adjacent to the enlargement side or reduction side of the cemented lens. In order from the enlargement side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a positive lens A fifth lens group having a refractive power of 6 and a sixth lens group having a positive refractive power,
2. At the time of zooming, among the six lens groups, four lens groups from the second lens group to the fifth lens group are configured to be movable along the optical axis. The zoom lens for projection according to any one of? In order from the magnification side, the first lens group having negative refractive power, the second lens group having positive refractive power, the third lens group having positive refractive power, the fourth lens group having positive refractive power, and the positive A fifth lens group having a refractive power of
2. The zoom lens according to claim 1, wherein three lens groups from the second lens group to the fourth lens group among the five lens groups are configured to be movable along the optical axis. The zoom lens for projection according to any one of?   10. A projection zoom lens according to claim 1, wherein the light source, the light valve, the illumination optical unit for guiding the light beam from the light source to the light valve, and the reduction side is telecentric. A projection zoom lens, wherein a light beam from the light source is modulated by the light valve and projected onto a screen by the projection zoom lens.

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