JP5530308B2 - Projection zoom lens and projection-type image display device - Google Patents

Description

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

  Projectors that magnify and project small original images displayed on liquid crystal display elements, DMDs (digital micromirror devices), etc. onto a screen are easy to obtain and are widely used because the images are high-definition. Yes.

  However, this type of projector requires an arrangement of a prism between the projection zoom lens and the display element as an optical system for combining red, green, and blue light emitted from the display element. Requires "long back focus".

  In addition, when the angle of light rays incident on the color synthesis optical system from the display element changes, the brightness of each color in the projected color image changes depending on the angle of view, resulting in an image that is difficult to see.

  In order to avoid this, it is preferable that the projection zoom lens has a “telecentric” property in which the angle of the principal ray is substantially parallel to the optical axis on the reduction side.

  As a projection zoom lens having these characteristics, it is known that a “negative lead” type zoom lens in which a “lens group having a negative refractive power” is arranged on the most enlargement side is suitable.

  However, it is difficult for the “negative lead” type zoom lens to give a large refractive power to the lens group contributing to zooming because of its configuration.

  For this reason, even if the zoom lens for projection of a general projector is referred to as “zoom”, the zoom ratio is as small as about 1.2 to 1.3 times.

  Recently, it has been strongly demanded to increase the “degree of freedom for the projector installation position” and greatly relax the restriction imposed on the distance between the projector and the screen. A larger zoom ratio is needed.

  Devices for realizing a zoom lens for projection having a large zoom ratio are known from Patent Documents 1 to 5 and the like, but nowadays, for a projection with a large zoom ratio and a bright angle (small F number) at the same time. A zoom lens is desired.

  Needless to say, the projector is becoming more compact, and the zoom lens for projection is preferably compact.

  In view of the above-described circumstances, the present invention has a large zoom ratio of 1.4 times or more, a large angle of view at a wide angle end: a large angle of view of 30 ° or more, and an F number of about 1.7. It is an object to realize a compact projection zoom lens to be obtained, and to realize a high-definition projection type image display device using the projection zoom lens.

  The projection zoom lens according to the present invention includes, in order from the enlargement side (image side) to the reduction side (object 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 negative refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, a sixth lens group having a positive refractive power, and a sixth lens group having a positive refractive power. Seven lens groups are arranged, and the reduction side has a substantially telecentric configuration.

Zooming is performed by moving the second, third, fourth, fifth, and sixth lens groups independently in the optical axis direction, and the first and seventh lens groups are “fixed during zooming”.
Focusing is performed by moving the first lens group in the optical axis direction.

Back focus in the air when the conjugate point on the magnification side is infinity: Bf, focal length of the entire system at the wide angle end: fw, focal length of the entire system at the telephoto end: ft, focal length of the first lens group: f1 The focal length of the third lens group: f3, and the focal length of the fourth lens group: f4 are:
(1) 1.3 <Bf / fw <2.2
(2) 1.4 <ft / fw <3.0
(3) 1.0 <| f1 / fw | <1.6
(4) 1.9 <f3 / fw <3.3
(5) 0.5 <| f4 / f3 | <1.0
(Claim 1).

  In the projection zoom lens according to claim 1, it is preferable that the aperture stop is arranged in the fourth group or in the vicinity thereof (claim 2).

  The projection zoom lens according to claim 1, wherein the first lens group is divided into two meniscus negative lenses having a convex surface on the enlargement side in order from the enlargement side to the reduction side, and on the enlargement side. It is preferable that at least three negative lenses having a large curvature are included, and at least one of the two meniscus negative lenses is configured as an aspherical surface.

  The zoom lens for projection according to any one of claims 1 to 3, wherein the second lens group is moved from the wide-angle end to the zoom intermediate region to the enlargement side during zooming, and from the zoom intermediate region to the telephoto end. May move to the reduction side ”(Claim 4).

  In the projection zoom lens according to any one of claims 1 to 4, the second lens group can be constituted by "one positive lens" (claim 5).

The projection zoom lens according to any one of claims 1 to 5, wherein the third lens group has a large curvature on the enlargement side and a lens having a convex surface on both sides: G3L1 in order from the enlargement side to the reduction side. Negative lens: a cemented lens in which two lenses of G3L2 are bonded together, a positive lens having a large curvature on the enlargement side: G3L3, and refractive indexes of G3L1 and G3L2 with respect to the d-line: N _G3L1 , N _G3L2 , Abbe Number: ν _G3L1 , ν _G3L2
(6) 0.02 < _{NG3L1- NG3L2} <0.25
(7) 5 <ν _G3L1 −ν _G3L2 <30
It is preferable to satisfy (Claim 6).

  The zoom lens for projection according to any one of claims 1 to 6, wherein the fifth lens group is "a negative lens having a large curvature on the reduction side in order from the enlargement side to the reduction side: G5L1, both surfaces being convex. Lens: G5L2 and negative lens having a large curvature on the enlargement side: G5L3, and the adjacent surfaces of the three lenses are bonded or have a small air gap. (Claim 7).

The projection zoom lens according to claim 7 is a lens constituting the fifth lens group: G5L1, G5L2, G5L3 with respect to the d-line, respectively, refractive index: N _G5L1 , N _G5L2 , N _G5L3 , Abbe number: ν _G5L1 , ν _G5L2 , ν _G5L3 , but the condition:
(8) 0.2 <(N _G5L1 + N _G5L3 ) / 2−N _G5L2 <0.5
(9) 35 < _νG5L2− ( _νG5L1 + _νG5L3 ) / 2 <70
Is preferably satisfied (claim 8).

The projection zoom lens according to claim 7 or 8, wherein the fifth lens group has convex surfaces: G5L2 Abbe number: ν _G5L2 , partial dispersion ratio: θ _gF , and conditions:
(10) 0 <θ _gF − (0.6438−0.001682ν _G5L2 ) <0.05
Is preferably satisfied (claim 9).

  The seventh lens group of the zoom lens for projection according to any one of claims 1 to 9 can be "configured by one positive lens" (claim 10).

  A projection type image display device according to the present invention includes the projection zoom lens according to any one of claims 1 to 10 (claim 11).

Supplement the explanation.
The projection zoom lens according to the present invention includes “seven lens groups” having “negative, positive, positive, negative, positive, positive, and positive” power from the enlargement side toward the reduction side. ˜Sixth five lens groups are independently moved on the optical axis and distributed to the optimal positions, thereby realizing good optical performance over a wide zoom range.

  The first lens group and the seventh lens group are fixed during zooming, but the first lens group moves in the optical axis direction during focusing. This configuration is convenient because it can “simplify the mechanical structure of the lens barrel”.

  Condition (1) is a condition for ensuring “necessary and sufficient back focus” for the projection zoom lens while maintaining a “large field angle”.

If the parameter: Bf / fw exceeds the lower limit of the condition (1) while maintaining a large angle of view, the back focus: Bf is shortened, and a color combining optical system such as a prism is provided between the projection zoom lens and the display element. It becomes difficult to place.
Further, if the upper limit of the condition (1) is exceeded while maintaining the desired “sufficient back focus”, the focal length: fw of the entire system decreases, and “the positive composite power of the entire system increases” It becomes difficult to correct aberrations.

  Condition (2) defines the zoom ratio of the projection zoom lens according to the present invention, and is a condition for ensuring the provision of a desired “large zoom ratio”.

  The projection zoom lens according to the present invention is suitable for realizing a “large zoom ratio” of a zoom ratio of 1.4 to 3.0.

  Condition (3) is a condition for achieving both a “large field angle” and good optical performance.

  When the parameter: | f1 / fw | exceeds the upper limit of the condition (3), | f1 | becomes too large, the negative refractive power of the first lens group becomes small, and a desired “large field angle” is obtained. It becomes difficult.

  If the lower limit of condition (3) is exceeded, a “large field angle” can be secured sufficiently, but | f1 | becomes too small and the negative refractive power of the first lens unit becomes excessive, resulting in coma aberration and field curvature. It is difficult to keep good aberrations such as the above.

  Condition (4) is a condition for achieving both “large zoom ratio” and “compactness”.

  When the parameter: f3 / fw exceeds the upper limit of the condition (4), the positive refractive power of the third lens group becomes small. Therefore, in order to maintain the “large zoom ratio”, the moving distance of the third lens group is set to “Compactness” is lost because it is necessary to increase the size.

  Condition (5) is a condition for realizing good optical performance.

  The projection zoom lens according to the present invention gives a large positive refractive power to the third lens group in order to obtain a “large zoom ratio”. However, as the refractive power increases, coma aberration, curvature of field, etc. Various aberrations are likely to occur.

  A negative refractive power is appropriately given to the fourth lens group so as to satisfy the condition (5), and an aberration opposite to that of the third lens group is generated to “cancel the aberration generated in the third lens group”. The effect makes it possible to achieve good optical performance over the entire “large zoom ratio”.

  That is, in the projection zoom lens according to the first aspect of the present invention, by satisfying the conditions (1) to (5) in the above-described group configuration and power arrangement, “a large angle of view and sufficient for a projection zoom lens are necessary. It is possible to achieve “a large zoom ratio”, “a large angle of view and compactness”, and “a good optical performance” while ensuring “smooth back focus”.

  By disposing the “aperture stop in the fourth group or in the vicinity thereof” as in the second aspect, the “telecentricity on the reduction side” in the first aspect can be easily realized.

  As in claim 3, the first lens group is composed of three meniscus-shaped negative lenses having a convex surface on the enlargement side in order from the enlargement side and a negative lens having a large curvature on the enlargement side. By having at least one of the two meniscus negative lenses having an aspherical surface, the first lens unit reduces various aberrations including distortion, and “enough back focus” And a lens group having sufficient refractive power to secure a “large field angle”.

  According to a fourth aspect of the present invention, the displacement of the second lens unit during zooming is set to “move to the enlargement side from the wide-angle end to the zoom intermediate region, and move to the reduction side from the zoom intermediate region to the telephoto end”. As a result, the variation of the focus position is effectively suppressed over the entire range of the “large zoom ratio”, and the “second lens group” is configured by a single positive lens with low cost as in claim 5. It becomes possible.

In the zoom lens for projection according to the present invention, it is preferable that a so-called variator, which is called “a lens group that contributes most to zooming when performing zooming”, is the third lens group.
In order to obtain a “large zoom ratio”, it is important to minimize the aberration that occurs as the variator moves.

  In this way, when the third lens group is provided with a variator function, the third lens group has a large curvature on the magnifying side: a lens having a convex surface on both sides: G3L1 in order from the magnifying side. A negative lens: a cemented lens in which two G3L2 lenses are bonded together, a positive lens having a large curvature on the enlargement side: three lenses of G3L3 ”, and the cemented lens according to the conditions (6) and (7). By limiting the refractive index difference and Abbe number difference, it is possible to achieve good image performance with little axial chromatic aberration and coma aberration over the entire “large zoom ratio”.

  Further, according to the seventh aspect of the invention, the fifth lens group is made up of “a negative lens having a large curvature on the reduction side in order from the enlargement side: G5L1, a lens having both convex surfaces: G5L2, and a negative lens having a large curvature on the enlargement side: G5L3 is composed of three lenses ”, and the“ adjacent surfaces ”of these three lenses are“ joined surfaces bonded with adhesive ”or“ adjacent with a small air gap ”to assemble the lens. This makes it easy to use a bright light source with a large amount of luminous flux, and improves reliability at high temperatures.

  In other words, a configuration with a large number of cemented surfaces can minimize the amount of eccentricity between the cemented lenses, facilitates securing the performance during lens assembly, improves yield, and has a configuration with few cemented surfaces. Thus, it is possible to use a bright light source with a large amount of light flux, and the reliability at high temperatures can be improved.

  The conditions (8) and (9) of claim 8 are conditions for regulating the refractive index and the Abbe number of three lenses: G5L1, G5L2, and G5L3 when the fifth lens is configured as in claim 7. Satisfying these conditions (8) and (9) makes it possible to realize good image performance with little lateral chromatic aberration and axial chromatic aberration.

  The condition (10) in claim 9 is a condition for regulating the Abbe number and the partial dispersion ratio of the optical glass constituting “lens having both convex surfaces: G5L2” in the fifth lens group.

As is well known, the “partial dispersion ratio: θ _gF ” indicates that the refractive index of the optical glass is “Ng” for the g-line (435.83 nm), “NF” for the F-line (486.13 nm), C As “NC” for the line (656.27 nm)
θ _gF = (Ng−NF) / (NF−NC)
It is a dimensionless quantity defined by.

  When the Abbe number and the partial dispersion ratio of the lens: G5L2 satisfy the condition (10), it is possible to further reduce the lateral chromatic aberration and obtain a good image over a wide angle of view.

  According to the tenth aspect, by configuring the seventh lens group by “one positive lens”, the cost of the projection zoom lens can be reduced.

As described above, according to the present invention, a novel projection zoom lens and a projection type image display apparatus (projector) using the same can be realized.
That is, as will be apparent from each embodiment described later, the projection zoom lens according to the present invention has a large zoom ratio of 1.4 times or more, a half field angle at the wide angle end: a large field angle of 30 ° or more, and an F number: It can be realized as a compact projection zoom lens capable of obtaining a good image with a brightness of about 1.7 and various aberrations well corrected.

  Therefore, the projection type image display apparatus equipped with the projection zoom lens described in the embodiments is compact, has a high degree of freedom with respect to the installation position, and can project a bright and good color image.

FIG. 3 is a diagram illustrating a lens configuration at a wide-angle end and a telephoto end in Example 1. FIG. 3 is a diagram illustrating spherical aberration, astigmatism, and distortion at the wide-angle end of Example 1. FIG. 3 is a diagram illustrating coma aberration at the wide-angle end in Example 1. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion at the zoom intermediate position according to the first exemplary embodiment. FIG. 6 is a diagram illustrating coma aberration at the zoom intermediate position according to the first exemplary embodiment. FIG. 4 is a diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end of Example 1. FIG. 3 is a diagram illustrating coma aberration at the wide-angle end in Example 1. 6 is a diagram illustrating a lens configuration at a wide-angle end and a telephoto end according to Embodiment 2. FIG. FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion at the wide-angle end in Example 2. 6 is a diagram illustrating coma aberration at a wide angle end according to Embodiment 2. FIG. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion in the zoom middle position according to the second exemplary embodiment. FIG. 6 is a diagram illustrating coma aberration at a zoom intermediate position according to the second exemplary embodiment. FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion at the telephoto end of Example 2. 6 is a diagram illustrating coma aberration at a wide angle end according to Embodiment 2. FIG. 6 is a diagram illustrating a lens configuration at a wide-angle end and a telephoto end according to Embodiment 3. FIG. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion at the wide-angle end in Example 3. 6 is a diagram illustrating coma aberration at a wide-angle end in Example 3. FIG. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion at the zoom intermediate position according to the third exemplary embodiment. FIG. 10 is a diagram illustrating coma aberration at a zoom intermediate position according to the third exemplary embodiment. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end of Example 3. 6 is a diagram illustrating coma aberration at a wide-angle end in Example 3. FIG. FIG. 6 is a diagram illustrating lens configurations at a wide-angle end and a telephoto end according to Example 4. It is a figure which shows the spherical aberration, astigmatism, and distortion aberration in the wide angle end of Example 4. FIG. 6 is a diagram showing coma aberration at the wide-angle end in Example 4. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, and distortion at the zoom intermediate position according to the fourth exemplary embodiment. FIG. 10 is a diagram illustrating coma aberration at a zoom intermediate position according to the fourth exemplary embodiment. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end of Example 4. FIG. 6 is a diagram showing coma aberration at the wide-angle end in Example 4. 10 is a diagram illustrating a lens configuration at a wide-angle end and a telephoto end according to Embodiment 5. FIG. It is a figure which shows the spherical aberration, astigmatism, and distortion aberration in the wide angle end of Example 5. FIG. 10 is a diagram illustrating coma aberration at the wide-angle end in Example 5. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, and distortion at the zoom intermediate position according to the fifth exemplary embodiment. FIG. 10 is a diagram illustrating coma aberration at a zoom intermediate position according to the fifth exemplary embodiment. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end according to Example 5. FIG. 10 is a diagram illustrating coma aberration at the wide-angle end in Example 5.

  1, 8, 15, 22, and 29 show five examples of the embodiment of the projection zoom lens. Each embodiment shown in these figures corresponds to Examples 1 to 5 to be described later. In each figure, “upper figure” shows the lens arrangement at the wide angle end, “lower figure” shows the lens arrangement at the telephoto end, and “arrow” "Represents the displacement of each lens unit during zooming from the wide-angle end to the telephoto end. The left side of the figure is the “enlargement side (image side)”, and the right side is the reduction side (object side).

  In addition, in order to avoid complication, a code | symbol is shared in each said figure, and the 1st lens group-the 7th lens group are shown sequentially by code | symbol G1-G7. In addition, “aperture stop” is indicated by symbol S, “prism as a color synthesis optical system” is indicated by symbol P, “cover glass” is indicated by symbol CG, and “display element” such as “liquid crystal display element” is indicated by symbol MD. Show.

  In any of the projection zoom lenses shown in the above drawings, the first lens group G1 having a negative refractive power and the second lens group G2 having a positive refractive power are sequentially arranged from the enlargement side to the reduction side. A third lens group G3 having a positive refractive power; a fourth lens group G4 having a negative refractive power; a fifth lens group G5 having a positive refractive power; a sixth lens group G6 having a positive refractive power; The seventh lens group G7 having a refractive power of 5 is arranged.

  In zooming, as indicated by arrows, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 are moved independently in the optical axis direction. Do.

  The aperture stop S is arranged in the fourth lens group G4 (FIG. 29) or in the vicinity thereof (in the vicinity of the enlargement side of the fourth lens group G4 in FIGS. 1, 8, 15, and 22).

  The first lens group G1 has, in order from the magnification side to the reduction side, two meniscus negative lenses having a convex surface on the magnification side and a negative lens having a large curvature on the magnification side. doing. In each example described later, the “second negative meniscus lens from the magnification side” is an aspherical lens.

  In each embodiment, the second lens group G2 of the projection zoom lens moves to the enlargement side from the wide-angle end to the zoom intermediate region and moves to the reduction side from the zoom intermediate region to the telephoto end during zooming. It consists of one positive lens.

  The third lens group G3 includes, in order from the magnifying side, a cemented lens in which two lenses of a convex surface on both sides and a negative lens having a large curvature on the magnifying side are bonded together, and a positive lens having a large curvature on the magnifying side It consists of

  The fourth lens group G4 is composed of three lenses, and in the forms of FIGS. 1, 15, 22, and 29, the two on the image side are joined, but the form of FIG. Then, all three lenses are independent. Moreover, in the form of FIG. 8, all the three lenses constituting the fifth lens group G are independent and are not joined.

  The fifth lens group G5 has, in order from the magnification side to the reduction side, a negative lens having a large curvature on the reduction side, a convex lens on both sides, and a negative lens having a large curvature on the enlargement side. The surfaces adjacent to each other of these three lenses are “joined (FIGS. 1, 15, 22, and 29) or have a small air gap (FIG. 8)”, and the seventh lens group G7 is “ It is composed of “a single positive lens”.

  Examples 1 to 5 corresponding to the embodiments shown in these figures all satisfy the conditions (1) to (10).

  In Examples 1 to 5 described later corresponding to these embodiments, the reduction side is substantially telecentric, and focusing is performed by moving the first lens group G1 in the optical axis direction.

  Hereinafter, five specific examples will be given.

  In each embodiment, the surface number is represented by a number counted from the enlargement side (screen side) to the reduction side (display element side), and the screen is the object plane and the image display surface of the display element MD is the image plane.

  “R” represents the radius of curvature of each surface (including the surface of the aperture stop S, the surface of the prism P for color synthesis, and the surface of the cover glass CG) (or the paraxial radius of curvature for an aspherical surface). "Represents the surface interval on the optical axis.

  “Nd” and “νd” indicate the refractive index and Abbe number of the material of each lens with respect to the d-line.

  “Effective diameter” indicates the maximum height of a ray passing from the optical axis.

  “Image height” is the maximum height of the display element surface from the optical axis, and “BF” is from the lens surface on the most reduced side in the air (without the prism and cover glass) when the conjugate point on the enlargement side is infinity. The distance to the paraxial image (back focus) is represented, and the “lens total length” is represented by adding the back focus to the distance from the most magnified lens surface to the most demagnified lens surface.

The aspherical shape has an intersection with the optical axis as the origin, height with respect to the optical axis: h, optical axis direction change: Z, paraxial radius of curvature: R, conic constant: K, nth-order aspherical coefficient: Using An, the well-known formula:
Z = (1 / R) · h ² / [1 + √ {1- (1 + K) · (1 / R) ² · h ² }]
+ A4 ・ h ⁴ + A6 ・ h ⁶ + A8 ・ h ⁸ + ・ ・ ・ + An ・ h ⁿ
And is specified by giving R, K, An.

  In each example, the unit of the quantity having “dimension of length” is “mm”, and various data are representative of “state at wide angle end”.

"Example 1"
Surface number RD Nd νd Effective diameter object surface ∞ (1400.000)
1 41.989 2.800 1.83481 42.7 25.385
2 23.979 1.811 20.764
3 * 14.170 3.800 1.53159 55.7 20.653
4 * 9.640 17.683 18.067
5 −49.374 1.800 1.59282 68.6 17.844
6 94.450 (variable) 18.239
7 89.622 4.964 1.90366 31.3 18.992
8 -125.398 (variable) 19.000
9 56.470 6.495 1.88300 40.8 16.515
10 −53.264 1.500 1.80809 22.8 16.263
11 −253.537 0.300 15.579
12 61.620 2.285 1.72047 34.7 14.500
13 104.464 (variable) 14.035
14 (Aperture) ∞ 1.339 8.196
15 −32.715 1.500 1.80420 46.5 8.163
16 −78.727 0.300 8.293
17 940.820 1.500 1.83400 37.3 8.333
18 29.109 2.173 1.61800 63.4 8.400
19 63.342 (variable) 8.500
20 120.778 1.500 1.80809 22.8 11.000
21 37.951 8.673 1.49700 81.6 11.612
22 −20.187 1.500 1.85026 32.3 12.505
23 −32.240 (variable) 13.702
24 114.140 5.655 1.49700 81.6 15.535
25 −42.225 (variable) 15.840
26 51.884 4.266 1.90366 31.3 16.490
27 ∞ 4.600 16.320
28 ∞ 21.000 1.51680 64.2 15.380
29 ∞ 5.850 12.586
30 ∞ 2.900 1.51680 64.2 11.390
31 ∞ 1.000 11.004
Image plane ∞ 10.800.

"Variable amount"
Zoom position Wide-angle end Medium telephoto end D6 3.217 1.893 3.606
D8 32.878 16.903 0.500
D13 15.077 21.142 21.801
D19 5.984 1.442 1.245
D23 0.500 2.305 0.300
D25 0.500 14.472 30.704.

"Aspherical data"
Third surface K = −0.699141,
A4 = −6.062 × 10 ⁻⁵ ,
A6 = 4.47681 × 10 ⁻⁸ ,
A8 = 5.40534 × 10 ⁻¹¹ ,
A10 = −2.15249 × 10 ⁻¹³ ,
A12 = 1.0955 × 10 ⁻¹⁶
4th surface K = -0.872731,
A4 = −8.16749 × 10 ⁻⁵ ,
A6 = 6.7099 × 10 ⁻⁸ ,
A8 = 9.22268 × 10 ⁻¹¹ ,
A10 = -3.73204 × 10 ^-13,
A12 = 3.21934 × 10 ⁻¹⁶ ,
A14 = −1.88955 × 10 ⁻¹⁸ ,
A16 = 3.35604 × 10 ⁻²¹ .

"Various data"
Focal length 14.919
F number 1.70
Half angle of view 36.0 °
Image height 10.8
BF 27.092
Total lens length 157.092.

"Parameter values for conditional expressions"
(1) Bf / fw = 1.816
(2) ft / fw = 2.0
(3) | f1 / fw | = 1.219
(4) f3 / fw = 2.709
(5) | f4 / f3 | = 0.786
(6) N _G3L1 −N _G3L2 = 0.07491
(7) ν _G3L1 −ν _G3L2 = 18.0
(8) (N _G5L1 + N _G5L3 ) / 2-N _G5L2 = 0.332218
(9) ν _G5L2 − (ν _G5L1 + ν _G5L3 ) = 54.1
(10) θ _gF − (0.6438−0.001682ν _G5L2 ) = 0.0375.

  As described above, FIG. 1 shows a lens configuration of the projection zoom lens according to the first embodiment.

  FIG. 2 shows a diagram of spherical aberration, astigmatism and distortion at the wide angle end of the projection zoom lens of Example 1, and FIG. 3 shows a diagram of coma aberration.

  Each aberration diagram shows the aberration of green light having a wavelength of 550 nm, but the spherical aberration diagram and coma aberration diagram also show the aberrations of wavelengths: 620 nm and 460 nm, representing red and blue light. In the astigmatism diagram, S represents the sagittal image, and M represents the aberration of the meridional image. The same applies to other aberration diagrams below.

  FIG. 4 shows a diagram of spherical aberration, astigmatism, and distortion at the zoom intermediate position (zoom ratio: 1.5), FIG. 5 shows a diagram of coma aberration, and spherical aberration at the telephoto end (zoom ratio: 2). FIG. 6 shows a diagram of point aberration and distortion, and FIG. 7 shows a diagram of coma aberration.

  In the case of the projection zoom lens of Example 1, the distance from the screen that is the object surface to the projection zoom lens is “1400 mm”, but the first lens group G1 is “moved in the optical axis direction and focused” It has become.

"Example 2"
Surface number RD Nd νd Effective diameter object surface ∞ (1500.000)
1 35.648 2.300 1.83400 37.3 23.067
2 21.947 2.006 19.209
3 * 13.970 3.700 1.53159 55.7 19.117
4 * 9.757 15.607 16.890
5 −42.935 1.600 1.61800 63.4 16.757
6 200.244 (variable) 17.176
7 92.571 4.723 1.90366 31.3 18.008
8 -108.576 (variable) 18.000
9 69.841 6.442 1.90366 31.3 14.568
10 −32.119 1.300 1.84666 23.8 14.340
11 412.313 0.300 13.509
12 51.961 3.164 1.71700 48.0 13.000
13 −4115.006 (variable) 12.716
14 (Aperture) ∞ 1.150 7.943
15 −33.565 1.200 1.80610 40.7 7.925
16 206.351 0.300 8.064
17 93.755 1.200 1.85026 32.3 8.134
18 37.520 0.300 8.223
19 39.994 1.719 1.49700 81.6 8.306
20 55.289 (variable) 8.500
21 88.018 1.300 1.80518 25.5 10.500
22 47.110 0.324 10.928
23 53.131 7.187 1.49700 81.6 11.095
24 −16.803 0.300 11.574
25 −16.967 1.300 1.75520 27.5 11.603
26 -29.984 (variable) 12.851
27 193.810 4.866 1.49700 81.6 14.318
28 −40.667 (variable) 14.659
29 50.747 4.118 1.90366 31.3 15.384
30 ∞ 4.600 15.237
31 ∞ 21.000 1.51680 64.2 14.483
32 ∞ 5.850 12.232
33 ∞ 2.900 1.51680 64.2 11.273
34 ∞ 1.000 10.962
Image plane ∞ 10.800.

"Variable amount"
Zoom position Wide-angle end Medium telephoto end D6 3.738 1.718 2.987
D8 31.689 16.140 0.500
D13 14.375 20.638 21.656
D20 6.794 2.143 1.199
D26 0.500 3.056 0.500
D28 0.500 13.901 30.754.

"Aspherical data"
Third surface K = −0.676577,
A4 = −5.93529 × 10 ⁻⁵ ,
A6 = 3.64932 × 10 ⁻⁸ ,
A8 = 5.40125 × 10 ⁻¹¹ ,
A10 = −1.86894 × 10 ⁻¹³ ,
A12 = 3.64429 × 10 ⁻¹⁷
4th surface K = -0.861985,
A4 = −7.98968 × 10 ⁻⁵ ,
A6 = 6.847 × 10 ⁻⁸ ,
A8 = 2.25381 × 10 ⁻¹¹ ,
A10 = −4.60566 × 10 ⁻¹³ ,
A12 = 2.61883 × 10 ⁻¹⁵ ,
A14 = −1.01396 × 10 ⁻¹⁷ ,
A16 = 1.23037 × 10 ⁻²⁰ .

"Various data"
Focal length 16.171
F number 1.68
Half angle of view 33.9 °
Image height 10.8
BF 27.059
Total lens length 151.061.

"Parameter values for conditional expressions"
(1) Bf / fw = 1.673
(2) ft / fw = 2.1
(3) | f1 / fw | = 1.219
(4) f3 / fw = 2.384
(5) | f4 / f3 | = 0.663
(6) N _G3L1 −N _G3L2 = 0.05700
(7) ν _G3L1 −ν _G3L2 = 7.5
(8) (N _G5L1 + N _G5L3 ) / 2−N _G5L2 = 0.28319
(9) ν _G5L2 − (ν _G5L1 + ν _G5L3 ) = 55.1
(10) θ _gF − (0.6438−0.001682ν _G5L2 ) = 0.0375.

  FIG. 8 illustrates a lens configuration of the projection zoom lens according to the second embodiment.

  FIG. 9 shows a diagram of spherical aberration, astigmatism and distortion at the wide angle end of the projection zoom lens of Example 2, and FIG. 10 shows a diagram of coma aberration. FIG. 11 is a diagram of spherical aberration, astigmatism and distortion at the zoom intermediate position (zoom ratio: 1.55), FIG. 12 is a diagram of coma aberration, and spherical aberration at the telephoto end (zoom ratio: 2.1). FIG. 13 shows a diagram of astigmatism and distortion, and FIG. 14 shows a diagram of coma aberration.

"Example 3"
Surface number RD Nd νd Effective diameter object surface ∞ (1500.000)
1 39.088 2.300 1.81600 46.6 24.127
2 25.480 1.427 20.819
3 * 14.411 3.700 1.53159 55.7 20.661
4 * 9.971 15.688 17.983
5 −72.031 1.600 1.61800 63.4 17.809
6 136.135 (Variable) 17.848
7 79.266 4.345 1.90366 31.3 18.603
8 -308.897 (variable) 18.500
9 48.860 6.387 1.88300 40.8 14.865
10 −45.620 1.300 1.84666 23.8 14.548
11 −315.082 0.300 13.880
12 60.615 2.267 1.71700 48.0 13.000
13 121.357 (variable) 12.571
14 (Aperture) ∞ 1.087 7.785
15 −34.315 1.200 1.80610 40.7 7.770
16 64.011 0.469 7.929
17 132.145 1.200 1.85026 32.3 7.977
18 32.651 1.999 1.78472 25.7 8.153
19 59.838 (variable) 9.000
20 68.702 1.300 1.80518 25.5 11.000
21 35.935 7.504 1.49700 81.6 11.479
22 −19.061 1.300 1.75211 25.1 11.964
23 -28.696 (variable) 12.954
24 103.136 4.402 1.49700 81.6 14.503
25 −57.085 (variable) 14.740
26 53.433 3.937 1.90366 31.3 15.272
27 ∞ 4.600 15.130
28 ∞ 21.000 1.51680 64.2 14.394
29 ∞ 5.850 12.197
30 ∞ 2.900 1.51680 64.2 11.261
31 ∞ 1.000 10.957
Image plane ∞ 10.800.

"Variable amount"
Zoom position Wide-angle end Medium telephoto end D6 6.850 1.693 3.326
D8 34.557 17.868 0.500
D13 12.392 19.398 21.182
D19 7.488 2.126 1.021
D23 0.500 4.076 0.500
D25 0.500 17.126 35.758.

"Aspherical data"
Third surface K = −0.672628,
A4 = −6.03854 × 10 ⁻⁵ ,
A6 = 2.70194 × 10 ⁻⁸ ,
A8 = 9.99743 × 10 ⁻¹¹ ,
A10 = −3.17526 × 10 ⁻¹³ ,
A12 = 1.88682 × 10 ⁻¹⁶
4th surface K = -0.874252,
A4 = −7.61889 × 10 ⁻⁵ ,
A6 = 5.44821 × 10 ⁻⁸ ,
A8 = 1.40222 × 10 ⁻¹⁰ ,
A10 = −7.30386 × 10 ⁻¹³
A12 = 2.44135 × 10 ⁻¹⁵ ,
A14 = −7.72286 × 10 ⁻¹⁸ ,
A16 = 9.94127 × 10 ⁻²¹ .

"Various data"
Focal length 17.260
F number 1.69
Half angle of view 32.2 °
Image height 10.8
BF 27.051
The total length of the lens is 153.050.

"Parameter values for conditional expressions"
(1) Bf / fw = 1.567
(2) ft / fw = 2.5
(3) | f1 / fw | = 1.435
(4) f3 / fw = 2.140
(5) | f4 / f3 | = 0.586
(6) N _G3L1 −N _G3L2 = 0.03634
(7) ν _G3L1 −ν _G3L2 = 17.0
(8) (N _G5L1 + N _G5L3 ) / 2-N _G5L2 = 0.28165
(9) ν _G5L2 − (ν _G5L1 + ν _G5L3 ) = 56.3
(10) θ _gF − (0.6438−0.001682ν _G5L2 ) = 0.0375.

  FIG. 15 shows the lens configuration of the projection zoom lens of Example 3.

  As described above, in Example 3, the F number at the wide angle end is 1.69, the half angle of view is 32.2 °, and the zoom ratio is as large as 2.5 while having a bright and wide angle of view.

  FIG. 16 shows a diagram of spherical aberration, astigmatism and distortion at the wide angle end of the projection zoom lens of Example 3, and FIG. 17 shows a diagram of coma aberration. FIG. 18 shows a diagram of spherical aberration, astigmatism and distortion at an intermediate zoom position (zoom ratio: 1.75), FIG. 19 shows a diagram of coma aberration, and spherical aberration at the telephoto end (zoom ratio: 2.5). FIG. 20 shows a diagram of astigmatism and distortion, and FIG. 21 shows a diagram of coma aberration.

Example 4
Surface number RD Nd νd Effective diameter object surface ∞ (1400.000)
1 42.120 2.800 1.88300 40.8 25.565
2 24.044 3.052 20.813
3 * 17.218 3.800 1.53159 55.7 20.688
4 * 10.883 16.947 17.898
5 −46.430 1.800 1.59282 68.6 17.647
6 73.645 (variable) 18.076
7 88.467 5.232 1.90366 31.3 18.964
8 -107.745 (variable) 19.000
9 61.310 6.054 1.88300 40.8 16.371
10 −58.206 1.500 1.80809 22.8 16.106
11 −288.247 0.300 15.465
12 67.154 2.314 1.72047 34.7 14.500
13 125.816 (variable) 14.109
14 (Aperture) ∞ 1.359 8.149
15 −31.634 1.500 1.80420 46.5 8.125
16 −56.344 0.300 8.271
17 −854.150 1.500 1.83400 37.3 8.284
18 25.211 2.596 1.61800 63.4 8.370
19 104.450 (variable) 8.500
20 136.549 1.500 1.80809 22.8 11.000
21 39.419 8.626 1.49700 81.6 11.619
22 −20.252 1.500 1.85026 32.3 12.523
23 −33.230 (variable) 13.752
24 136.918 5.623 1.49700 81.6 15.539
25 −40.778 (variable) 15.870
26 50.756 4.491 1.90366 31.3 16.647
27 -1708.576 4.600 16.481
28 ∞ 21.000 1.51680 64.2 15.499
29 ∞ 5.850 12.633
30 ∞ 2.900 1.51680 64.2 11.406
31 ∞ 1.000 11.010
Image plane ∞ 10.800.

"Variable amount"
Zoom position Wide-angle end Medium telephoto end D6 3.674 3.405 4.645
D8 29.181 14.768 0.500
D13 17.773 23.090 23.603
D19 5.579 1.338 1.055
D23 0.500 2.136 0.300
D25 0.500 12.470 27.103.

"Aspherical data"
Third surface K = −0.522179,
A4 = −5.12775 × 10 ⁻⁵ ,
A6 = 6.31693 × 10 ⁻⁸ ,
A8 = −1.58223 × 10 ⁻¹¹ ,
A10 = −1.49952 × 10 ⁻¹³ ,
A12 = 9.78127 × 10 ⁻¹⁷
4th surface K = −0.840528,
A4 = −6.43833 × 10 ⁻⁵ ,
A6 = 6.29638 × 10 ⁻⁸ ,
A8 = 1.36247 × 10 ⁻¹⁰ ,
A10 = −6.85954 × 10 ⁻¹³ ,
A12 = 5.82277 × 10 ⁻¹⁶ ,
A14 = −1.36712 × 10 ⁻¹⁸ ,
A16 = 3.35604 × 10 ⁻²¹ .

"Various data"
Focal length 13.886
F number 1.69
Half angle of view 38.0 °
Image height 10.8
BF 27.109
Total lens length 157.110.

"Parameter values for conditional expressions"
(1) Bf / fw = 1.952
(2) ft / fw = 1.8
(3) | f1 / fw | = 1.150
(4) f3 / fw = 3.098
(5) | f4 / f3 | = 0.854
(6) N _G3L1 −N _G3L2 = 0.07491
(7) ν _G3L1 −ν _G3L2 = 18.0
(8) (N _G5L1 + N _G5L3 ) / 2-N _G5L2 = 0.332218
(9) ν _G5L2 − (ν _G5L1 + ν _G5L3 ) = 54.1
(10) θ _gF − (0.6438−0.001682ν _G5L2 ) = 0.0375.

  FIG. 22 shows the lens configuration of the projection zoom lens of Example 4.

  Although the half angle of view at the wide angle end is as high as 38 ° and the F-number is 1.69, which is bright, the zoom ratio is 1.8.

  FIG. 23 shows a diagram of spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 4, and FIG. 24 shows a diagram of coma aberration. FIG. 25 shows a diagram of spherical aberration, astigmatism and distortion at the zoom intermediate position (zoom ratio: 1.4), FIG. 26 shows a diagram of coma aberration, and spherical aberration at the telephoto end (zoom ratio: 1.8). FIG. 27 shows astigmatism and distortion, and FIG. 28 shows coma.

"Example 5"
Surface number RD Nd νd Effective diameter object surface ∞ (1400.000)
1 42.217 2.941 1.83481 42.7 25.019
2 23.590 1.789 20.353
3 * 14.352 3.800 1.53159 55.7 20.235
4 * 9.737 17.334 17.717
5 −48.752 1.800 1.59282 68.6 17.473
6 112.662 (variable) 17.836
7 103.151 4.472 1.90366 31.3 18.485
8 -136.085 (variable) 18.500
9 58.153 6.837 1.88300 40.8 16.594
10 −50.626 1.500 1.80809 22.8 16.326
11 −197.672 0.300 15.689
12 56.003 2.586 1.74950 35.0 14.500
13 114.119 (variable) 14.042
14 −38.014 1.500 1.77250 49.6 8.756
15 −94.391 1.347 8.544
16 (Aperture) ∞ 0.300 8.101
17 −88793.979 1.500 1.83400 37.3 8.116
18 23.255 2.403 1.61800 63.4 8.196
19 56.576 (variable) 8.322
20 95.224 1.500 1.80809 22.8 10.300
21 33.271 8.377 1.48749 70.4 10.866
22 −19.463 1.500 1.85026 32.3 11.774
23 −34.767 (variable) 13.018
24 115.676 6.031 1.49700 81.6 14.772
25 −36.271 (variable) 15.173
26 50.742 4.515 1.90366 31.3 15.931
27 ∞ 4.600 15.743
28 ∞ 21.000 1.51680 64.2 14.890
29 ∞ 5.450 12.348
30 ∞ 2.900 1.51680 64.2 11.336
31 ∞ 1.000 10.985
Image plane ∞ 10.800.

"Variable amount"
Zoom position Wide-angle end Medium telephoto end D6 3.156 2.104 4.460
D8 31.315 15.672 0.500
D13 14.685 19.790 20.209
D19 7.512 2.680 1.227
D23 0.500 1.961 0.300
D25 0.500 15.461 30.973
"Aspherical data"
Third surface K = −0.660112,
A4 = −5.97368 × 10 ⁻⁵ ,
A6 = 4.27542 × 10 ⁻⁸ ,
A8 = 5.09093 × 10 ⁻¹¹ ,
A10 = −2.18145 × 10 ⁻¹³ ,
A12 = 8.2393 × 10 ⁻¹⁷
4th surface K = -0.875333,
A4 = −7.79942 × 10 ⁻⁵ ,
A6 = 6.28258 × 10 ⁻⁸ ,
A8 = 1.15936 × 10 ⁻¹⁰ ,
A10 = −3.89484 × 10 ⁻¹³ ,
A12 = −3.29698 × 10 ⁻¹⁷ ,
A14 = −1.13954 × 10 ⁻¹⁸ ,
A16 = 3.35604 × 10 ⁻²¹ .

"Various data"
Focal length 14.916
F number 1.70
Half angle of view 36.0 °
Image height 10.8
BF 26.683
Total lens length 156.683.

"Parameter values for conditional expressions"
(1) Bf / fw = 1.789
(2) ft / fw = 2.0
(3) | f1 / fw | = 1.230
(4) f3 / fw = 2.473
(5) | f4 / f3 | = 0.804
(6) N _G3L1 −N _G3L2 = 0.07491
(7) ν _G3L1 −ν _G3L2 = 18.0
(8) (N _G5L1 + N _G5L3 ) / 2−N _G5L2 = 0.34169
(9) ν _G5L2 − (ν _G5L1 + ν _G5L3 ) = 42.9
(10) θ _gF − (0.6438−0.001682ν _G5L2 ) = 0.0092.

  FIG. 29 shows the lens configuration of the projection zoom lens of Example 5.

  In Example 5, the aperture stop S is placed between the lenses constituting the fourth lens group G4.

  FIG. 30 shows a diagram of spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 5, and FIG. 31 shows a diagram of coma aberration. FIG. 32 shows a diagram of spherical aberration, astigmatism, and distortion at the zoom intermediate position (zoom ratio: 1.5), FIG. 33 shows a diagram of coma aberration, and spherical aberration, non-magnitude at the telephoto end (zoom ratio: 2). A diagram of point aberration and distortion is shown in FIG. 34, and a diagram of coma aberration is shown in FIG.

In each embodiment, each aberration is corrected well in a wide zoom range from the wide-angle end to the telephoto end, and the performance is good. Also, the zoom ratio is as large as 1.4 or more, and the F number is as bright as 1.7 or less.

  Therefore, the projection zoom lens according to any one of the first to fifth embodiments is mounted on the well-known “three-plate type color projector” to project a bright, good color image with a high degree of freedom with respect to the installation position. A possible projection type image display device can be realized.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group S Aperture stop
P Prism CG Cover glass MD Display element

JP 2006-084971 A JP 2006-091480 A JP 2007-248840 A JP 2007-256424 A JP 2008-046259 A

Claims (11)

In order from the enlargement side to the reduction 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, and a first lens group having a negative refractive power. Four lens groups, a fifth lens group having a positive refractive power, a sixth lens group having a positive refractive power, and a seventh lens group having a positive refractive power are arranged, and the reduction side has a substantially telecentric configuration. ,
Zooming is performed by moving the second, third, fourth, fifth, and sixth lens groups independently in the optical axis direction,
Focusing is performed by moving the first lens group in the optical axis direction.
Back focus in the air when the conjugate point on the magnification side is infinity: Bf, focal length of the entire system at the wide angle end: fw, focal length of the entire system at the telephoto end: ft, focal length of the first lens group: f1 The focal length of the third lens group is f3, and the focal length of the fourth lens group is f4.
(1) 1.3 <Bf / fw <2.2
(2) 1.4 <ft / fw <3.0
(3) 1.0 <| f1 / fw | <1.6
(4) 1.9 <f3 / fw <3.3
(5) 0.5 <| f4 / f3 | <1.0
Projection zoom lens characterized by satisfying The projection zoom lens according to claim 1,
A projection zoom lens characterized in that an aperture stop is disposed in or near the fourth lens group. The projection zoom lens according to claim 1 or 2,
The first lens group has at least three lenses: a meniscus negative lens having a convex surface on the enlargement side and a negative lens having a large curvature on the enlargement side in order from the enlargement side to the reduction side. And
A projection zoom lens, wherein at least one of the two meniscus negative lenses has an aspherical surface. The projection zoom lens according to any one of claims 1 to 3,
The zoom lens for projection is characterized in that the second lens group moves to the enlargement side from the wide-angle end to the zoom intermediate region and moves to the reduction side from the zoom intermediate region to the telephoto end during zooming. The projection zoom lens according to any one of claims 1 to 4 ,
The second lens group includes a single positive lens, and a projection zoom lens.
The projection zoom lens according to any one of claims 1 to 5,
The third lens group includes, in order from the magnification side to the reduction side, a cemented lens in which two lenses of a convex lens: G3L1 and a negative lens: G3L2 having a large curvature on the magnification side are bonded to each other on the magnification side. Positive lens with a large curvature: composed of G3L3,
Refractive indexes with respect to the d-line of each of the above G3L1 and G3L2: N _G3L1 , N _G3L2 , Abbe numbers: ν _G3L1 , ν _G3L2 are as _follows :
(6) 0.02 < _{NG3L1- NG3L2} <0.25
(7) 5 <ν _G3L1 −ν _G3L2 <30
Projection zoom lens characterized by satisfying The zoom lens for projection according to any one of claims 1 to 6,
The fifth lens group consists of three lenses, a negative lens having a large curvature on the reduction side: G5L1, a lens having a convex surface on both sides: G5L2, and a negative lens having a large curvature on the enlargement side: G5L3 in order from the enlargement side to the reduction side. A projection zoom lens, characterized in that adjacent surfaces of the three lenses are joined or have a small air gap. The projection zoom lens according to claim 7,
Lenses constituting the fifth lens group: G5L1, G5L2, and G5L3 with respect to d-line refractive indexes: N _G5L1 , N _G5L2 , N _G5L3 , Abbe number: ν _G5L1 , ν _G5L2 , ν _G5L3
(8) 0.2 <(N _G5L1 + N _G5L3 ) / 2−N _G5L2 <0.5
(9) 35 < _νG5L2− ( _νG5L1 + _νG5L3 ) / 2 <70
Projection zoom lens characterized by satisfying The projection zoom lens according to claim 7 or 8,
In the fifth lens group, both surfaces are convex: G5L2 Abbe number: ν _G5L2 , partial dispersion ratio: θ _gF , conditions:
(10) 0 <θ _gF − (0.6438−0.001682ν _G5L2 ) <0.05
Projection zoom lens characterized by satisfying The projection zoom lens according to any one of claims 1 to 9,
The seventh lens group includes a single positive lens, and a projection zoom lens.   A projection-type image display device comprising the projection zoom lens according to any one of claims 1 to 10.

Images