JP5101959B2 - Projection type zoom lens and projection type display device - Google Patents

Description

  The present invention relates to a five-group eight-projection projection zoom lens mounted on a projection display device or the like and a projection display device including the projection zoom lens, and more particularly to a transmissive or reflective liquid crystal display device. The present invention relates to a projection type zoom lens and a projection type display device for enlarging and projecting a light beam carrying image information from a light valve such as a DMD (digital micromirror device) 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, and in particular, three light valves are used so as to correspond to RGB three primary color illumination lights. In this case, the illumination light is modulated, the light modulated by the individual light valves is combined by a prism or the like, and an image is displayed on a screen via a projection lens.

  In the light valve described above, miniaturization and high-definition have progressed rapidly, and along with the spread of personal computers, the demand for giving presentations using such projection display devices has increased, Since there is a demand for an aspect that is convenient and easy to install, there is an increasing demand for higher performance, smaller size, and lighter weight for projection display devices. As a result, the projection lens is also strongly desired to be smaller and lighter.

  As projection zoom lenses satisfying such requirements, for example, those disclosed in Patent Documents 1 and 2 below, which are configured by a 5-group, 8-lens lens, are known. That is, these projection zoom lenses move the second, third, and fourth lens groups along the optical axis at the time of zooming, and the third and / or fourth lens group includes a cemented lens. Therefore, consideration is given to correcting chromatic aberration.

JP 2004-109896 A JP 2005-156963 A

  As described above, the projection zoom lenses described in Patent Documents 1 and 2 satisfy the requirements of small size and light weight, and are configured to satisfactorily correct chromatic aberration.

  However, when configured as the projection zoom lens described in Patent Documents 1 and 2 above, other aberrations, particularly the image surface tilting, are large. Degradation of the image quality in the reproduced images was remarkable.

  The present invention has been made in view of the above circumstances, and has a five-group, eight-lens configuration, and is capable of reducing the size and weight, and can properly correct various aberrations, particularly image surface tilt. An object of the present invention is to provide a lens and a projection display device.

The projection zoom lens of the present invention is
In order from the magnification side, a first lens group having negative refracting power, consisting of an aspheric lens having at least one aspheric surface and a negative lens having a concave surface facing the reduction side, and a magnification side A second lens group composed of one positive lens having a convex surface, a third lens group composed of one positive lens having a convex surface facing the enlargement side, and a forty-first lens composed of a negative lens having a concave surface facing the magnification side. Three lenses, a lens, a forty-second lens arranged so that a negative air lens is formed between the first lens and a forty-third lens consisting of a positive lens with a convex surface facing the reduction side To a fourth lens group arranged in this order, and a fifth lens group composed of one positive lens with a convex surface facing the enlargement side,
At the time of zooming, at least the third lens group and the fourth lens group are configured to move in the optical axis direction, and the reduction side is configured to be substantially telecentric,
Furthermore, it is configured to satisfy the following conditional expressions (1) and (2).

3.0 ≦ | fG1 / fw | (1)
-20.0 ≦ fn / fw ≦ −0.5 (2)
However,
fw: focal length of the entire lens system at the wide-angle end fG1: focus of an aspherical lens having the smallest absolute value of power in the first lens group
Distance fn: Focal length of the air lens

Moreover, it is preferable that the following conditional expressions (3) to (5) are satisfied.
−2.5 ≦ f1 / fw ≦ −0.9 (3)
0.9 ≦ f3 / fw ≦ 4.0 (4)
1.5 ≦ f5 / fw ≦ 5.0 (5)
However,
f1: focal length of the first lens group f3: focal length of the third lens group f5: focal length of the fifth lens group

  Further, at the time of zooming, only the third lens group and the fourth lens group can be configured to move in the optical axis direction.

  On the other hand, at the time of zooming, it may be configured such that only the second lens group, the third lens group, and the fourth lens group move in the optical axis direction. In this case, the second lens group and the third lens group can be configured to move together in the optical axis direction.

  Moreover, it is preferable that the air lens has a biconvex shape.

In addition, it is preferable that the magnifying side of the forty-second lens is a concave surface and further satisfies the following conditional expression (2 ′).
−7.0 ≦ fn / fw ≦ −0.5 (2 ′)

  Further, it is preferable that at least one surface of the fourth lens group is an aspherical surface.

  Further, it is preferable that the focus adjustment is performed by moving the first lens group in the optical axis direction.

  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 zoom lenses described above. The light beam is light-modulated by the light valve and projected onto a screen by the projection zoom lens.

  According to the projection zoom lens and the projection display apparatus using the same of the present invention, the whole is simply configured by eight lenses in five groups, and it is easy to achieve a reduction in size and weight. Further, the fourth lens group is constituted by three lenses of a 41st lens, a 42nd lens and a 43rd lens, and a negative air lens is formed between the 41st lens and the 42nd lens. In addition, since the focal length (power) of the air lens is defined within a predetermined range by the above equation (2), it is possible to particularly favorably correct the tilt of the image plane.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The projection zoom lens of the embodiment shown in FIG. 1 (representing the lens of Example 1 as a representative) has a first lens group G ₁ having a negative refractive power in order from the enlargement side, each having a positive refractive power. The second lens group G ₂ to the fifth lens group G ₅ having the above-mentioned configuration, the reduction side is configured to be substantially telecentric, and a glass block (including a filter unit) 2 mainly including a color synthesizing prism is provided at the subsequent stage. An image display surface 1 of a light valve such as a liquid crystal display panel is provided. In the figure, X represents the optical axis.

Here, the first lens group G ₁ is reduced first lens of a negative lens having a concave surface facing the side L _1, and the second lens at least one surface is aspherical lens made aspheric (plastic) L ₂ (In Examples 3 to 6, the first lens L ₁ made of a plastic aspheric lens having at least one aspheric surface and the second lens L _{2 made of} a negative lens having a concave surface facing the reduction side) Consist of). The second lens group G ₂ is composed of only the third lens L ₃ of a positive lens having a convex surface on the enlargement side. The third lens group G ₃ is composed of only the fourth lens L ₄ is a positive lens having a convex surface on the enlargement side. The fourth lens group G ₄ is composed of a positive lens having a negative air lens is arranged to be formed between the fifth lens L _5, a lens of a negative lens having a concave surface facing the magnification side first 6 lenses L ₆ and a seventh lens L _{7 made of} a positive lens having a convex surface facing the reduction side. The fifth lens group G ₅ includes only the eighth lens L ₈ formed of a positive lens having a convex surface on the enlargement side. Thus configured results, between the fifth lens L ₅ and the sixth lens L ₆ constituting the fourth lens group G _4, so that the negative air lens is formed.

Thus, by forming a negative air lens between the fifth lens L ₅ and the sixth lens L ₆ in the fourth lens group G ₄ , the range of the following conditional expression (2) is satisfied. Thus, it is possible to correct the tilt of the image plane.

Note that this negative air lens has a more improved correction function when it has a biconvex shape. Furthermore, when this negative air lens is arranged in the vicinity of the pupil, the correction function is further improved. In the present embodiment, the pupil, between the third lens group G ₃ of the fourth lens group G ₄ (Examples 1 and 2), or the third lens group G ₃ juxtaposed with the fourth lens group G ₄ Therefore, the negative air lens is arranged in the vicinity of the pupil.

Further, during zooming, (corresponding to Examples 1-5) the third lens group G ₃ and it is preferable to integrally aperture stop 3 (also acceptable that a mask) is configured to move.

  Since the projection zoom lens according to the present embodiment is a negative lead type zoom lens as described above, it is easy to widen the angle and it is possible to ensure a back focus with an appropriate length. .

The projection type zoom lens of this embodiment, during zooming, at least two lens groups (Example 1, the third lens group G ₃ and the fourth lens group G _4, in Examples 2-6, the The second lens group G ₂ , the third lens group G _3, and the fourth lens group G ₄ (of which, in Examples 3 to 5, the second lens group G ₂ and the third lens group G ₃ move together). By moving in the optical axis direction, the zoom function is provided. By using two lens groups, the third lens group G ₃ and the fourth lens group G ₄ , at the time of zooming, the lens barrel can be simplified and the entire system can be reduced in cost and compact. Can be achieved. On the other hand, the aberration correction can be made better by using the three lens groups of the second lens group G ₂ , the third lens group G ₃ and the fourth lens group G ₄ as the moving group. In this case, in the case where the second lens group G ₂ and the third lens group G ₃ by moving integrally, and in the case where the movable units and two lens groups, the three lens groups moving group, A system having the advantages of both can be obtained.

  Further, it is preferable that all the moving lens groups are configured to move to the enlargement side upon zooming from the wide-angle end to the telephoto end. In the present embodiment, the zoom ratio can be set larger by configuring in this way.

  However, this means that for each of the moving lens groups, the position at the telephoto end is set on the enlargement side rather than the position at the wide-angle end, and in the intermediate region, It does not exclude moving to the reduction side once.

The focus adjustment is performed by moving the first lens group G ₁ in the optical axis direction.

In addition, the projection zoom lens according to the present embodiment is configured to satisfy the following conditional expressions (1) and (2).
3.0 ≦ | fG1 / fw | (1)
-20.0 ≦ fn / fw ≦ −0.5 (2)
However,
fw: focal length of the entire lens system at the wide-angle end fG1: aspherical lens having a small absolute value of the first lens group G ₁ most power in
Focal length fn: Focal length of air lens

Furthermore, it is preferable that the following conditional expressions (3) to (5) are satisfied.
−2.5 ≦ f1 / fw ≦ −0.9 (3)
0.9 ≦ f3 / fw ≦ 4.0 (4)
1.5 ≦ f5 / fw ≦ 5.0 (5)
However,
f1: focal length of the first lens group _{G 1} f3: a third focal length of the lens unit _{G 3} f5: focal length of the fifth lens group _{G 5}

Here, the technical significance of the conditional expressions (1) to (5) will be described.
First, the conditional expression (1) is, but also as using a plastic lens in the first lens group G ₁ of constituent lenses, defines the range of the first lens group G ₁ of the power that can minimize the influence of temperature change It is. That is, if the lower limit of condition (1), too strong and the first lens group G ₁ of the power, the materials affected by using the temperature change, such as plastic as a first constituent lenses of the lens group G ₁ It becomes a problem.

  Conditional expression (2) defines the range of the power of the air lens that can improve aberration correction. That is, if the lower limit of conditional expression (2) is not reached, aberration correction, particularly sagittal image plane correction becomes difficult. On the other hand, when the upper limit is exceeded, it becomes difficult to correct aberrations, particularly coma.

It should be noted that by replacing the conditional expression (2) with satisfying the following conditional expression (2 ′), the operational effect of the aberration correction is improved.
−7.0 ≦ fn / fw ≦ −0.5 (2 ′)

Further, by setting so as to satisfy the following conditional expression (2 ″) instead of the conditional expression (2 ′), the effect of the aberration correction described above becomes extremely good.
−5.0 ≦ fn / fw ≦ −0.5 (2 ″)

Conditional expression (3) defines a range in which aberration correction is good and the lens back can have an appropriate length. That is, when the value falls below the lower limit of conditional expression (3),
The lens back becomes too short, and it becomes difficult to insert a color composition portion or the like. On the other hand, if the upper limit is exceeded, aberration correction becomes difficult, the lens back becomes too long, and the system becomes large.

  Conditional expression (4) defines a range in which aberration correction is good and the system can be made compact. In other words, if the lower limit of conditional expression (4) is not reached, aberration correction becomes difficult. On the other hand, when the upper limit is exceeded, the movement amount of the lens becomes too large and the system becomes large.

  Conditional expression (5) also defines a range in which aberration correction is satisfactory and the system can be made compact. In other words, if the lower limit of conditional expression (5) is not reached, aberration correction becomes difficult. On the other hand, when the upper limit is exceeded, the lens back becomes too long and the system becomes large.

  Here, each of the projection zoom lenses of the following examples includes an aspheric lens, and the aspheric shape is represented by the following aspheric expression.

  Next, an example of a projection display device equipped with the projection zoom lens described above will be described with reference to FIG. The projection display device shown in FIG. 13 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 zoom 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 to be light-modulated, color-combined by the cross dichroic prism 14, and projected onto a screen (not shown) by the projection zoom 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 apparatus according to the present embodiment uses the projection zoom lens according to the present embodiment, the projection display apparatus has a wide angle, good image quality of a projected image, and is a bright, small, and lightweight projection display apparatus. Can do.

  The projection zoom lens according to the present invention is not limited to the usage as a projection zoom lens of a projection display device using a transmissive liquid crystal display panel, but may be a reflection type liquid crystal display panel or DMD. It is also possible to use it as a projection zoom lens of an apparatus using the above light modulation means.

  Further, as shown in FIGS. 14A and 14B, a positive lens 15a or a negative lens that functions as a magnification color correction unit between any one of the transmissive liquid crystal panels 11a to 11c and the cross dichroic prism 14. By inserting 15b, it is possible to correct the lateral chromatic aberration of the entire system even when correction is difficult only by the zoom lens.

Hereinafter, the projection zoom lens of the present invention will be further described with reference to specific examples.
<Example 1>
The projection zoom lens according to Example 1 is configured as shown in FIG. 1 as described above. That is, in this projection zoom lens, in order from the magnification side, the first lens group G ₁ is composed of a first lens L _{1 made of} a negative meniscus lens having a concave surface facing the reduction side and an aspheric lens made of both surfaces aspheric. and a second lens _{L 2} Metropolitan made. The second lens group _{G 2} is composed of only the third lens _{L 3} which is a biconvex lens. The third lens group _{G 3} is composed of only the fourth lens _{L 4} is a biconvex lens. The fourth lens group G ₄ includes a fifth lens L ₅ formed of a biconcave _lens, a negative air lens between the fifth lens L ₅ is arranged to be formed, a convex surface directed toward the reduction side And a sixth lens L _{6 made of} a positive meniscus lens and a seventh lens L _{7 made of} a positive meniscus lens having a convex surface facing the reduction side. The fifth lens group _{G 5} includes only the eighth lens _{L 8} made of a biconvex lens. The aperture stop 3 is arranged to move the third lens group G ₃ and is arranged between the fourth lens group G _4, and integrally third lens group G _3. Further, a mask may be provided in place of the aperture stop 3 or together with the aperture stop 3.

Further, during zooming is due to the transition from the wide angle end to the telephoto end, the third lens group G ₃ and the fourth lens group G ₄ is moved to the magnification side independently of one another.

The focus adjustment is performed by moving the first lens group G ₁ in the optical axis direction.

  The radius of curvature R of each lens surface in the first embodiment (standardized by setting the focal length of the entire lens system to 1.0; the same applies to the following tables), the center thickness of each lens, and the air gap D between each lens ( Table 1 shows the refractive index Nd and Abbe number νd of the d-line of each lens in the upper part of the table. In Table 1 and Tables 2 to 6 to be described later, the numbers corresponding to the symbols R, D, Nd, and νd are sequentially increased from the enlargement side.

The middle part of Table 1 shows the values of the constants K and A _{3 to} A ₁₂ corresponding to each aspheric surface, and the lower part of Table 1 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (the distance between the second lens group G ₂ and the third lens group G ₃₎ variable interval 1, (distance between the third lens group G ₃ and the fourth lens group G ₄₎ variable spacing 2 and variable spacing 3 (the distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is shown.

  Table 7 shows numerical values corresponding to the above conditional expressions in the first embodiment.

  FIG. 7 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens of Example 1. 7 and the following FIGS. 8 to 12, the spherical aberration diagrams show the aberrations for the d-line, F-line, and C-line light, 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. 7, according to the projection zoom lens of Example 1, the angle of view 2ω at the wide angle end is as wide as 59.6 degrees, the F value is 2.50, and each aberration, in particular, Image plane tilt is well corrected.

  Further, as shown in Table 7, according to the projection zoom lens of Example 1, the conditional expressions (1) to (5) are satisfied, and the conditional expression (2 ′) is also satisfied.

<Example 2>
FIG. 2 shows a schematic configuration of the projection zoom lens according to the second embodiment. Projection zoom lens according to Example 2 has been substantially the same configuration as that of Example 1, mainly on the expansion side of the third lens L ₃ is a convex surface constituting the second lens group G ₂ The seventh lens L ₇ constituting the fourth lens group G ₄ is a biconvex lens, and the second lens is moved along with the movement from the wide-angle end to the telephoto end during zooming. The difference is that the group G ₂ , the third lens group G _3, and the fourth lens group G ₄ move to the enlargement side independently of each other.

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

The middle part of Table 2 shows the values of constants K and A _{3 to} A ₁₂ corresponding to each aspheric surface, and the lower part of Table 2 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (distance between the first lens group _{G 1} and second lens group _{G 2)} variable spacing 1, (distance between the second lens group _{G 2} and the third lens group _{G 3)} variable spacing 2, variable spacing 3 are shown (the third lens group _{G 3} and the distance between the fourth lens group _{G 4)} and a variable interval 4 (distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is.

  Table 7 shows numerical values corresponding to the above conditional expressions in Example 2.

  FIG. 8 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens of Example 2.

  As apparent from FIG. 8, according to the projection zoom lens of Example 2, the angle of view 2ω at the wide angle end is as wide as 59.6 degrees, the F value is 2.50, and each aberration, in particular, Image plane tilt is well corrected.

  Further, as shown in Table 7, according to the projection zoom lens of Example 2, the conditional expressions (1) to (5) are satisfied, and the conditional expression (2 ′) is also satisfied.

<Example 3>
A schematic configuration of the projection zoom lens according to Example 3 is shown in FIG. Projection zoom lens according to Example 3 has been substantially the same configuration as that of Example 1, primarily, the first lens group G ₁ is a plastic aspherical lens both surfaces are aspherical It consists of a first lens L ₁ and a biconcave lens the second lens L ₂ Metropolitan made, a seventh lens L ₇ constituting the fourth lens group G ₄ becomes of a biconvex lens, constituting the fifth lens group G ₅ It is different in that the 8 lens L ₈ is a positive meniscus lens having a convex surface facing the magnification side. Further, aperture stop 3 but in terms that are configured to move the third lens group G ₃ integrally with the same as those of Example 1, the third lens group G ₃ and the second lens group G ₂ Is different in that it is arranged between The second lens group G ₂ and the third lens group G ₃ is different even in that integrally moved.

  Table 3 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 3.

The middle part of Table 3 shows the values of the constants K and A _{3 to} A ₁₂ corresponding to the respective aspheric surfaces. The lower part of Table 3 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (distance between the first lens group G ₁ and second lens group G ₂₎ variable spacing 1, (distance between the third lens group G ₃ and the fourth lens group G ₄₎ variable spacing 2 and variable spacing 3 (the distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is shown.

  Table 7 shows numerical values corresponding to the above conditional expressions in Example 3.

  FIG. 9 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens of Example 3.

  As is apparent from FIG. 9, according to the projection zoom lens of Example 3, the angle of view 2ω at the wide angle end is as wide as 59.4 degrees, the F value is as bright as 2.01, and each aberration, particularly Image plane tilt is well corrected.

  Further, as shown in Table 7, according to the projection zoom lens of Example 3, conditional expressions (1) to (5) are satisfied, and conditional expressions (2 ′) and (2 ″) are also satisfied. ing.

<Example 4>
FIG. 4 shows a schematic configuration of the projection zoom lens according to Example 4. The projection zoom lens according to Example 4 has substantially the same configuration as that of Example 3, but the sixth lens L ₆ is mainly composed of the lenses constituting the fourth lens group G _4. becomes a negative meniscus lens having a convex surface facing the reduction side, the seventh lens L ₇ is a positive meniscus lens having a convex surface facing the reduction side, the eighth lens L ₈ constituting the fifth lens group G ₅ is both It is different in that it consists of a convex lens. The second lens group G ₂ and the third lens group G ₃ is different even in that integrally moved.

  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 and the Abbe number νd of each lens at the d-line in Example 4.

The middle part of Table 4 shows the values of constants K and A _{3 to} A ₁₂ corresponding to each aspheric surface, and the lower part of Table 4 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (distance between the first lens group G ₁ and second lens group G ₂₎ variable spacing 1, (distance between the third lens group G ₃ and the fourth lens group G ₄₎ variable spacing 2 and variable spacing 3 (the distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is shown.

  Table 7 shows numerical values corresponding to the above conditional expressions in Example 4.

  FIG. 10 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens according to Example 4.

  As is apparent from FIG. 10, according to the projection zoom lens of Example 4, the angle of view 2ω at the wide angle end is as wide as 59.8 degrees, the F value is as bright as 1.80, and each aberration, particularly Image plane tilt is well corrected.

  As shown in Table 7, according to the projection zoom lens of Example 4, the conditional expressions (1) to (5) are satisfied, and the conditional expressions (2 ′) and (2 ″) are also satisfied. ing.

<Example 5>
A schematic configuration of the projection zoom lens according to Example 5 is shown in FIG. The projection zoom lens according to Example 5 has substantially the same configuration as that of Example 3, but the sixth lens L ₆ is mainly composed of the lenses constituting the fourth lens group G _4. consists bi-aspherical lens, a seventh lens L ₇ is a positive meniscus lens having a convex surface facing the reduction side, the eighth lens L ₈ constituting the fifth lens group G ₅ are different in that a biconvex lens ing. In addition to the aperture stop 3, the reduction side of the second lens group G _2, is different in that it is configured to have placed a mask 4 to move the second lens group G ₂ and integrally. The second lens group G ₂ and the third lens group G ₃ is different even in that integrally moved.

  Table 5 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 and the Abbe number νd of each lens at the d-line in Example 5.

The middle part of Table 5 shows the values of the constants K and A _{3 to} A ₁₂ corresponding to each aspheric surface, and the lower part of Table 5 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (distance between the first lens group G ₁ and second lens group G ₂₎ variable spacing 1, (distance between the third lens group G ₃ and the fourth lens group G ₄₎ variable spacing 2 and variable spacing 3 (the distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is shown.

  Table 7 shows numerical values corresponding to the conditional expressions in Example 5.

  FIG. 11 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens according to Example 5.

  As is apparent from FIG. 11, according to the projection zoom lens of Example 5, the angle of view 2ω at the wide angle end is as wide as 59.6 degrees, the F value is as bright as 1.80, and each aberration, particularly Image plane tilt is well corrected.

  As shown in Table 7, according to the projection zoom lens of Example 5, the conditional expressions (1) to (5) are satisfied, and the conditional expressions (2 ′) and (2 ″) are also satisfied. ing.

<Example 6>
A schematic configuration of the projection zoom lens according to Example 6 is shown in FIG. Projection zoom lens according to Example 6, but has a substantially same structure as that of Example 3, mainly, among the lenses constituting the fourth lens group G _4, the sixth lens L ₆ is two-sided The seventh lens L ₇ is an aspheric lens, the seventh lens L ₇ is a positive meniscus lens having a convex surface on the reduction side, and the eighth lens L ₈ constituting the fifth lens group G ₅ is a biconvex lens. Yes. Further, at the time of zooming, the second lens group G ₂ , the third lens group G _3, and the fourth lens group G ₄ move to the enlargement side independently of each other with the movement from the wide-angle end to the telephoto end. Is different. Further, aperture stop 3, are arranged on the reduction side near the second lens group G _2, and is configured to move the second lens group G ₂ and integrally.

The middle part of Table 6 shows the values of the constants K and A _{3 to} A ₁₂ corresponding to each aspheric surface, and the lower part of Table 6 shows the wide-angle end (wide) and the telephoto end (tele). in each case, (distance between the first lens group _{G 1} and second lens group _{G 2)} variable spacing 1, (distance between the second lens group _{G 2} and the third lens group _{G 3)} variable spacing 2, variable spacing 3 are shown (the third lens group _{G 3} and the distance between the fourth lens group _{G 4)} and a variable interval 4 (distance between the fourth lens group _{G 4} and the fifth lens group _{G 5)} is.

  Table 7 shows numerical values corresponding to the conditional expressions in Example 6.

  FIG. 12 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and lateral chromatic aberration) at the wide-angle end (wide) and the telephoto end (tele) of the projection zoom lens according to Example 6.

  As is apparent from FIG. 12, according to the projection zoom lens of Example 6, the angle of view 2ω at the wide angle end is as wide as 59.6 degrees, the F value is 1.72, and each aberration, in particular, Image plane tilt is well corrected.

  Further, as shown in Table 7, according to the projection zoom lens of Example 6, the conditional expressions (1) to (5) are satisfied, and the conditional expressions (2 ′) and (2 ″) are also satisfied. ing.

FIG. 1 is a schematic diagram illustrating a configuration of a projection zoom lens according to Embodiment 1 of the present invention at a wide-angle end (wide) and a telephoto end (tele). FIG. 6 is a schematic diagram illustrating a configuration of a projection zoom lens according to Embodiment 2 of the present invention at a wide-angle end (wide) and a telephoto end (tele). FIG. 6 is a schematic diagram illustrating a configuration of a projection zoom lens according to Embodiment 3 of the present invention at a wide-angle end (wide) and a telephoto end (tele). FIG. 6 is a schematic diagram showing a configuration at a wide-angle end (wide) and a telephoto end (tele) of a projection zoom lens according to Example 4 of the present invention. FIG. 6 is a schematic diagram illustrating a configuration of a projection zoom lens according to Embodiment 5 of the present invention at a wide-angle end (wide) and a telephoto end (tele). FIG. 7 is a schematic diagram illustrating a configuration of a projection zoom lens according to Example 6 of the present invention at a wide-angle end (wide) and a telephoto end (tele). Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 1 Aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 2 Aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 3 Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 4 Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 5 Aberration diagrams showing various aberrations (spherical aberration, astigmatism, distortion and lateral chromatic aberration) of the projection zoom lens of Example 6 1 is a schematic configuration diagram of a projection display device according to an embodiment of the present invention. The schematic block diagram for demonstrating a part of projection type display apparatus which concerns on the modification of this invention

Explanation of symbols

G ₁ ~G ₅ lens group L ₁ ~L ₈ lens R ₁ to R ₂₀ curvature of the lens surface such as a radius D ₁ to D ₁₉ lens spacing (lens thickness)
X Optical axis 1 Image display surface 2 Glass block (including filter part)
DESCRIPTION OF SYMBOLS 3 Aperture stop 4 Mask 10 Projection type zoom lens 11a-c Transmission type liquid crystal panel 12, 13 Dichroic mirror 14 Cross dichroic prism 15a, b Magnification color correction means (lens)
16a-c condenser lens 18a-c total reflection mirror 20 light source

Claims (9)

In order from the magnification side, a first lens group having negative refracting power, consisting of an aspheric lens having at least one aspheric surface and a negative lens having a concave surface facing the reduction side, and a magnification side A second lens group composed of one positive lens having a convex surface, a third lens group composed of one positive lens having a convex surface facing the enlargement side, and a forty-first lens composed of a negative lens having a concave surface facing the magnification side. Three lenses, a lens, a forty-second lens arranged so that a negative air lens is formed between the first lens and a forty-third lens consisting of a positive lens with a convex surface facing the reduction side To a fourth lens group arranged in this order, and a fifth lens group composed of one positive lens with a convex surface facing the enlargement side,
During zooming, the third only lens group and the fourth lens group is configured to move in the optical axis direction Rutotomoni, the reduction side is configured into a substantially telecentric,
Further, the projection zoom lens is configured to satisfy the following conditional expressions (1) and (2).
3.0 ≦ | fG1 / fw | (1)
-20.0 ≦ fn / fw ≦ −0.5 (2)
However,
fw: focal length of the entire lens system at the wide-angle end fG1: focal length of an aspherical lens having the smallest absolute value of power in the first lens group fn: focal length of the air lens   In order from the magnification side, a first lens group having negative refracting power, consisting of an aspheric lens having at least one aspheric surface and a negative lens having a concave surface facing the reduction side, and a magnification side A second lens group composed of one positive lens having a convex surface, a third lens group composed of one positive lens having a convex surface facing the enlargement side, and a forty-first lens composed of a negative lens having a concave surface facing the magnification side. Three lenses, a lens, a forty-second lens arranged so that a negative air lens is formed between the first lens and a forty-third lens consisting of a positive lens with a convex surface facing the reduction side To a fourth lens group arranged in this order, and a fifth lens group composed of one positive lens with a convex surface facing the enlargement side,
  At the time of zooming, only the second lens group, the third lens group, and the fourth lens group are configured to move in the optical axis direction, and the reduction side is configured to be substantially telecentric,
  Further, the projection zoom lens is configured to satisfy the following conditional expressions (1) and (2).
      3.0 ≦ | fG1 / fw | (1)
    -20.0 ≦ fn / fw ≦ −0.5 (2)
    However,
      fw: focal length of the entire lens system at the wide-angle end
      fG1: Focal point of the aspherical lens having the smallest absolute power value in the first lens group
distance
      fn: Focal length of the air lens The following conditional expression (3) to (5) according to claim 1 or 2 projection zoom lens according to, characterized by satisfying the.
−2.5 ≦ f1 / fw ≦ −0.9 (3)
0.9 ≦ f3 / fw ≦ 4.0 (4)
1.5 ≦ f5 / fw ≦ 5.0 (5)
However,
f1: focal length of the first lens group f3: focal length of the third lens group f5: focal length of the fifth lens group 3. The projection zoom lens according to claim 2, wherein the zoom lens is configured so that the second lens unit and the third lens unit move together in the optical axis direction during zooming. It said air lens projection type zoom lens according to any one of the four claim 1, characterized in that there is a biconvex shape. The second lens enlarged side is constituted by the concave, the following condition expression (2 ') a projection zoom lens according to any one of claims 1 to 5, characterized by satisfying the.
−7.0 ≦ fn / fw ≦ −0.5 (2 ′) Projection zoom lens according to any one of claims 1 to 6, characterized in that at least one surface of the fourth lens group is an aspherical surface. Focus adjustment, a projection zoom lens of any one of claims 1 to 7, characterized in that it is configured to perform by moving the first lens group in the optical axis direction. 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 zoom lens according to any one of claims 1 to 8 , wherein the light beam from the light source A projection display device that modulates light with the light valve and projects it onto a screen with the projection zoom lens.

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