Projection zoom lens and projection type image display device

Abstract

To provide a novel projection zoom lens with a seven-lens configuration.SOLUTION: A projection zoom lens comprises, in order from a magnification side to a reduction side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive or negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having positive refractive power. In zooming, the first and seventh lens groups G1, G7 are stationary while the second through sixth lens groups G2-G6 move along an optical axis. The projection zoom lens satisfies a condition expressed as: 0.5<|f1 / fw|<1.0, where fw represents a focal length of the entire system at a wide-angle end, and f1 represents a focal length of the first lens group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a projection zoom lens and a projection type image display device. Regarding the equipment do. [Background technology]

[0002] 2. Description of the Related Art Projection-type image display devices, such as projectors and head-up displays, which enlarge and project a small original image displayed on the image display surface of an image display element such as a liquid crystal display element or a DMD onto a projection surface such as a screen, have become widely used because they can easily display large, high-definition images.

[0003] Projection lenses mounted on projectors and the like are generally zoom lenses that can easily change the size of a projected image, and various types have been proposed. Among them, projection zoom lenses with a relatively large projection angle of view are known to be those described in Patent Documents 1 to 3. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to realize a novel projection zoom lens having a seven-lens group configuration. [Means for solving the problem]

[0005] The projection zoom lens of the present invention comprises, in order from the enlargement side to the reduction 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 positive refractive power, a fifth lens group having positive or negative refractive power, a sixth lens group having positive refractive power, and a seventh lens group having positive refractive power, and during zooming, the first lens group and the seventh lens group are fixed, and the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group are each fixed. , while changing the spacing between adjacent lens groups. Move along the optical axis, the first lens group is composed of, in order from the enlargement side to the reduction side, a first sub-lens group having negative refractive power, a second sub-lens group consisting of one aspheric lens, a third sub-lens group having a positive lens having a large curvature on the enlargement side, and a fourth sub-lens group having negative refractive power, and during focusing, the second sub-lens group and the third sub-lens group move on the optical axis, The focal length of the entire system at the wide-angle end is fw, and the focal length of the first lens group is f1, and the conditions are as follows: (1) 0.5 <|f1 / fw|< 1.0 Satisfy. Effect of the Invention

[0006] According to this invention, a novel projection zoom lens having a seven-lens group configuration can be realized. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram for explaining a projection zoom lens according to a first embodiment. [Diagram 2] 4 is a diagram showing spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 1. FIG. [Diagram 3] 4 is a diagram showing coma aberration at the wide-angle end of the projection zoom lens of Example 1. FIG. [Figure 4] 4 is a diagram showing spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 1. FIG. [Diagram 5] 4 is a diagram showing coma aberration at the telephoto end of the projection zoom lens of Example 1. FIG. [Figure 6] FIG. 11 is a diagram for explaining a projection zoom lens according to a second embodiment. [Figure 7] 11A and 11B are diagrams illustrating spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 2. [Figure 8] 11 is a diagram showing coma aberration at the wide-angle end of the projection zoom lens of Example 2. FIG. [Figure 9] 11A and 11B are diagrams illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 2. [Figure 10] 13 is a diagram showing coma aberration at the telephoto end of the projection zoom lens of Example 2. FIG. [Figure 11] 11 is a diagram for explaining a projection zoom lens according to a third embodiment. FIG. [Figure 12] 11A and 11B are diagrams illustrating spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 3. [Figure 13]13 is a diagram showing coma aberration at the wide-angle end of the projection zoom lens of Example 3. FIG. [Figure 14] 13A and 13B are diagrams illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 3. [Figure 15] 13 is a diagram showing coma aberration at the telephoto end of the projection zoom lens of Example 3. FIG. [Figure 16] FIG. 11 is a diagram for explaining a projection zoom lens according to a fourth embodiment. [Figure 17] 13A and 13B are diagrams illustrating spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 4. [Figure 18] 13 is a diagram showing coma aberration at the wide-angle end of the projection zoom lens of Example 4. FIG. [Figure 19] 13A and 13B are diagrams illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 4. [Figure 20] 13 is a diagram showing coma aberration at the telephoto end of the projection zoom lens of Example 4. FIG. [Figure 21] 13 is a diagram for explaining a projection zoom lens according to a fifth embodiment. FIG. [Figure 22] 13A and 13B are diagrams illustrating spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 5. [Diagram 23] 13 is a diagram showing coma aberration at the wide-angle end of the projection zoom lens of Example 5. FIG. [Figure 24] 13A and 13B are diagrams illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 5. [Diagram 25] 13 is a diagram showing coma aberration at the telephoto end of the projection zoom lens of Example 5. FIG. [Figure 26] 4 is a diagram showing spherical aberration, astigmatism, and distortion when the projection zoom lens of Example 1 is focused at the wide-angle end with a projection distance of 800 mm. FIG. [Figure 27] 4 is a diagram showing coma aberration when the projection zoom lens of Example 1 is focused at a wide-angle end and a projection distance of 800 mm. FIG. [Figure 28] FIG. 1 is a diagram for explaining an embodiment of a projector (projection type image display device). [Figure 29] FIG. 1 is a diagram for explaining an embodiment of an imaging device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The following description will be given with reference to the drawings. Five embodiments of the projection zoom lens of the present invention are shown in Figures 1, 6, 11, 16, and 21. The embodiments shown in these figures correspond to specific Examples 1 to 5 described later in the order of the figures. In order to avoid complication, the reference numerals are common to the embodiments shown in FIGS. First, in these five figures, the upper one shows the "lens group arrangement at the wide-angle end," and the lower one shows the "lens group arrangement at the telephoto end." In each figure, the right side is the "reduction side" and the left side is the "enlargement side," with the image display element such as a DMD being placed on the reduction side and the projection surface such as a screen being placed on the enlargement side. In these five figures, the symbol MD represents the "image display surface" that displays the green image out of the three color images of red, green, and blue, the symbol CG represents the cover glass that protects the image display surface, and the symbol P represents the color synthesis prism, which is a "color synthesis optical system" that synthesizes the red, blue, and green color image light into color image light.

[0009] As shown in FIG. 1 etc., the projection zoom lens of the present invention comprises, in order from the enlargement side (left side of the drawing) to the reduction side (right side of the drawing), a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive or negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having positive refractive power. During zooming, the first lens group G1 and the seventh lens group G7 are fixed, and 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 fixed. , while changing the spacing between adjacent lens groups.Each of them moves in the optical axis direction. That is, with respect to zooming, the first lens group G1 and the seventh lens group G7 are "fixed groups", and the second through sixth lens groups G2 to G6 are "moving groups". The first lens group G1 is composed of, from the magnification side, a first sub-lens group SG1 having negative refractive power, a second sub-lens group SG2 consisting of one aspheric lens, a third sub-lens group SG3 having a positive lens with a large curvature on the magnification side, and a fourth sub-lens group SG4 having negative refractive power, and when focusing, the second sub-lens group SG2 and the third sub-lens group SG3 move on the optical axis.

[0010] The focal length of the entire system at the wide-angle end: fw, and the focal length of the first lens group G1: f1 are set to satisfy the following conditions: (1) 0.5 <|f1 / fw|< 1.0 Satisfy. The above configuration of the projection zoom lens is referred to as "Configuration 1."

[0011] The projection zoom lens of "Configuration 1" has a back focus in air: Bf, and a focal length of the entire system at the wide-angle end: fw, which satisfy the following conditions: (2) 1.0 < Bf / fw < 5.0 It is preferable to satisfy the following. This configuration is called "Configuration 2". The projection zoom lens of "Configuration 1 or Configuration 2" can be configured so that the aperture diaphragm S is disposed in the fifth lens group G5 and displaces integrally with the fifth lens group G5 during zooming, as shown in Figure 1. This configuration is called "Configuration 3". 1 and other figures, the aperture diaphragm S is disposed near the enlargement side of the fifth lens group G5, but it may be disposed within the fifth lens group G5. In either case, the aperture diaphragm moves integrally with the fifth lens group G5 during zooming.

[0012] Which of the projection zoom lenses in "Configuration 1" or "Configuration 3" is However, the first sub-lens group SG1 can be “constructed entirely of negative lenses.” This construction is called “Construction 4.” "Configuration 1 to Configuration 4" In the projection zoom lens, one aspheric lens constituting the second sub-lens group SG2 can be "molded from plastic". "Configuration 5" It is called.

[0013] "Configuration 5"In this example, the second sub-lens group SG2 is a single aspheric lens, and the position of this aspheric lens on the optical axis is optimized according to the projection distance, enabling good adjustment of field curvature and distortion. Since this aspheric lens is disposed "inside the first lens group G1, where the outer shape of the lens is likely to be large," it is preferable from a cost perspective to mold it from plastic.

[0014] "Configuration 1 to Configuration 5" In any of the projection zoom lenses, the fourth sub-lens group SG4 can be configured by arranging, in order from the enlargement side, a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the enlargement side. "Configuration 6" It is called. "Configuration 1 to Configuration 6" In each of the projection zoom lenses, the fourth sub-lens group SG4 has the "strongest negative refractive power" among the four sub-lens groups (first to fourth sub-lens groups SG1 to SG4) constituting the first lens group G1, and the focal length f1 of the first lens group G1 and the focal length fSG4 of the fourth sub-lens group SG4 satisfy the following conditions: (3) 1.5 < fSG4 / f1 < 3.5 This configuration can be configured to satisfy the following. "Configuration 7" It is called. "Configuration 1 to Configuration 7" In any of the projection zoom lenses, the second lens group G2 can be constructed with one positive lens. "Configuration 8" It is called. "Configuration 1 to Configuration 8" In any of the projection zoom lenses, the fourth lens group G4 can be constructed with one positive lens. "Configuration 9" It is called. "Configuration 1 to Configuration 9" In any of the projection zoom lenses, the seventh lens group G7 is composed of one positive lens, and the Abbe number: νG7L and the partial dispersion ratio: θgF of the material of the positive lens satisfy the following conditions: (4) νG7L < 35 (5) 0.0005< θgF-(0.6438-0.001682νG7L) This configuration can be configured to satisfy the following. "Configuration 10"It is called. In addition, the "partial dispersion ratio: θgF" in condition (5) is the ratio of the material (optical glass) constituting the lens to the Refractive index for g-line (435.83 nm): Ng Refractive index for F line (486.13 nm): NF Refractive index for C line (656.27 nm): NC Due to θgF=(Ng-NF) / (NF-NC) is defined as: "Configuration 1 to Configuration 10" It is preferable that the projection zoom lens is a telecentric optical system in which the entrance pupil position on the reduction side is located at almost infinity. "Configuration 11" It is called.

[0015] "Configuration 11" By using a telecentric optical system in which the entrance pupil (the pupil on the reduction side) is positioned at almost infinity as shown above, it is possible to efficiently capture the light rays incident from the image display element. As in "Configuration 3," by disposing the aperture diaphragm S in the fifth lens group G5 and configuring it so that the aperture diaphragm S moves integrally with the fifth lens group G5 during zooming, it becomes easier to achieve telecentricity on the reduction side of the projection zoom lens.

[0016] As described above, the projection zoom lens of this invention is composed of seven lens groups G1 to G7 with refractive power distributions of "negative-positive-positive-positive-negative-positive-positive" or "negative-positive-positive-positive-positive-positive" from the magnification side, and during zooming, the five lens groups G2 to G6 move on the optical axis and are allocated to optimal positions, thereby achieving good optical performance. The first lens group G1 and the seventh lens group G7 are fixed during zooming. Configuration 1 As described above, the first lens group G1 is composed of the first to fourth sub-lens groups SG1 to SG4, and focusing is performed by moving the second and third sub-lens groups SG2 and SG3 in the first lens group G1, which are easier to access, in the optical axis direction, thereby simplifying the mechanical structure of the lens barrel.

[0017] The significance of the above conditions (1) to (5) will now be explained. In the following, conditions (1) to (5) will be referred to as "conditional formulas (1) to (5)." Condition (1) satisfies the requirement for achieving both a large angle of view and good optical performance. When the parameter |f1 / fw| exceeds its upper limit, |f1| becomes too large, the negative refractive power of the first lens group G1 becomes small, and it becomes difficult to achieve a "large angle of view." If the lower limit of conditional expression (1) is exceeded, a “large angle of view” can be sufficiently ensured, but |f1| becomes too small, the negative refractive power of the first lens group G1 becomes excessively large, and it becomes difficult to maintain good aberrations such as coma and curvature of field. By satisfying conditional expression (1), the projection zoom lens of the present invention can have a large angle of view.

[0018] Condition (2) is a condition for ensuring a necessary and sufficient back focus for a projection zoom lens while maintaining a "large angle of view." If the parameter: Bf / fw falls below the lower limit of conditional expression (2), the back focus: Bf becomes short, making it difficult to place a "color synthesis optical system" such as a color synthesis prism between the projection zoom lens and the display element. If the upper limit of conditional expression (2) is exceeded while maintaining a "sufficient back focus," the focal length: fw of the entire system becomes small, making it difficult to correct various aberrations. In "Configuration 8", the fourth sub-lens group SG4 has the strongest negative refractive power among the first to fourth sub-lens groups SG1 to SG4 that constitute the first lens group G1. By imparting a strong negative refractive power to the fourth sub-lens group SG4, it becomes easier to ensure the flatness of the image surface, and it becomes easier to move the position of the exit pupil (the pupil on the enlargement side) to the enlargement side, making it possible to reduce the outer shape of the first lens group G1, and making it easier to make the projection zoom lens more compact. To achieve such effects, it is preferable to configure the fourth sub-lens group SG4 by arranging, in order from the enlargement side, two negative lenses, a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the enlargement side, as in "Configuration 7". In such a configuration, conditional expression (3) defines the appropriate range of negative refractive power that the fourth sub-lens group SG4 has within the first lens group G1. If the upper (lower) limit of conditional expression (3) is exceeded, the negative refractive power of the fourth sub-lens group SG4 becomes weak (strong), making it difficult to maintain the flatness of the image surface and the effect of positioning the exit pupil on the enlargement side tends to be insufficient.

[0019] Conditional expressions (4) and (5) define the Abbe number and the partial dispersion ratio of the positive lens constituting the seventh lens group G7. By forming the seventh lens group G7 from optical materials that satisfy these conditional expressions, it is possible to realize good imaging performance with little lateral chromatic aberration. In the projection zoom lens of this invention, in each of the embodiments described below, the refracting surface of each lens is in contact with air, and a so-called "cemented lens" in which multiple lenses are bonded together is not used, but it goes without saying that a "cemented lens" may be used. If a cemented lens is used, the amount of decentering between the cemented lenses can be minimized, making it easier to ensure performance during assembly and improving the yield of manufacturing projection zoom lenses. Furthermore, if the lenses are separated by a small air gap, reliability at high temperatures is improved, and a bright light source with a large amount of luminous flux can be used.

[0020] The projection type image display device (zoom lens) of the present invention, by incorporating the above-mentioned projection zoom lens, can realize bright and good images with a large angle of view and a small F-number, as in the embodiments described later. In addition, since the original image displayed on the image display surface of an image display element such as a liquid crystal display element or a DMD and the display surface such as a screen are conjugate points on the enlargement side and reduction side of a projection zoom lens, by placing an imaging element at the conjugate point on the reduction side, it is possible to realize an imaging device that captures image information of the enlarged projection image displayed on the display surface. Another example of an imaging device is a "camera."

[0021] "Example" Five specific examples are given below. In the data showing each embodiment, the "surface number" represents the number counted from the enlargement side (screen side) to the reduction side (image display surface side), with the screen being the "object surface" and the image display surface being the "image surface." "R" represents the radius of curvature (paraxial radius of curvature for aspheric surfaces) of each surface (including the surface of aperture stop S, color synthesis prism P, and the surface of cover glass CG), and "D" represents the distance between adjacent surfaces on the optical axis. Note that the aperture stop is listed in the data as the unit "stop." "Nd" and "νd" indicate the refractive index and Abbe number for the d line of each lens material.

[0022] "Image height" is the maximum height from the optical axis on the image display surface, "BF" represents the distance (back focus) from the lens surface on the most reducing side to the image display surface in air (without the color synthesis prism and cover glass), and "total lens length" represents the "distance from the lens surface on the most enlarging side to the lens surface on the most reducing side" plus the back focus.

[0023] The shape of an aspheric surface is expressed by the well-known formula: h is the height relative to the optical axis, Z is the displacement in the optical axis direction, R is the paraxial radius of curvature, K is the conic constant, and An is the n-th order aspheric coefficient. Z = (1 / R) h 2 / [1+√{1-(1+K)·(1 / R) 2 h 2}] +A3·h 3 +A4·h 4 +A5·h 5 +···+An·h n and is specified by giving R, K, and An above.

[0024] "Example 1" Example 1 is a specific example of the embodiment shown in FIG. As shown in FIG. 1, the projection zoom lens of Example 1 is composed of, from the enlargement side (the left side of the figure), a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7, and during zooming, the first lens group G1 and the seventh lens group G7 are fixed, and the second lens group G2 to the sixth lens group G6 each move independently in the optical axis direction. A color synthesis system including a color synthesis prism P and a cover glass CG is inserted between the projection zoom lens and the image display surface MD of the image display element.

[0025] The focal length of the first lens group G1 is negative, but the focal lengths of the second lens group G2 to the seventh lens group G7 are all positive. That is, the refractive power distribution of the first lens group G1 to the seventh lens group G7 is "negative-positive-positive-positive-positive-positive-positive" from the enlargement side to the reduction side. The first lens group G1 is composed of, from the magnification side, a first sub-lens group SG1 consisting of three negative lenses, a second sub-lens group SG2 consisting of one aspherical lens, a third sub-lens group SG3 consisting of a positive lens and a negative lens with a large curvature on the magnification side, and a fourth sub-lens group SG4 consisting of two negative lenses: a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the magnification side.

[0026] The aperture stop S is located near the enlargement side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming.

[0027] In the projection zoom lens of the first embodiment, the distance from the screen, which is the object plane, to the projection zoom lens is 1000 mm, and the projection zoom lens is in a focused state at this distance. The second lens group G2, the fourth lens group G4 and the seventh lens group G7 each include one positive lens. The zoom ratio of the projection zoom lens of the first embodiment is 1.26, and the positions of the moving groups at the wide-angle end and the telephoto end are shown below as variable data. The various data shown are representative of the wide-angle end state. Note that the unit of length in the data for each of the following examples is "mm."

[0028] "Example 1 Data" Surface number RD Nd νd Object surface ∞ 1000.0000 1 123.0008 7.0000 1.80420 46.50 2 84.2003 11.0101 3 100.3208 5.9000 1.80420 46.50 4 71.6976 11.9851 5 91.7862 5.0000 1.80420 46.50 6 61.3410 12.4909 7* 42.0987 5.0000 1.50966 56.38 8* 22.1662 6.1303 9 58.8976 9.5743 1.80518 25.46 10 78.5500 15.3308 11 -479.6713 3.7000 1.80420 46.50 12 856.3312 18.5934 13* -140.8645 2.1000 1.76802 49.24 14* 58.2465 16.0708 15 -33.7163 2.3000 1.49700 81.61 16 136.6909 (variable) 17 335.0491 11.0353 1.67270 32.17 18 -56.7289 (variable) 19 106.7500 12.1759 1.85883 30.00 20 -77.5918 0.3000 21 -76.0333 2.3000 1.92286 20.88 22 -299.6375 (variable) 23 91.2905 6.0042 1.51823 58.96 24 -252.5844 (variable) 25(Aperture) ∞ 6.2442 26 -41.3939 1.2000 1.95375 32.32 27 -45265.7919 0.3000 28 54.0983 7.3891 1.59270 35.31 29 -51.3684 (variable) 30 85.6523 1.3000 1.95375 32.32 31 29.3868 0.3000 32 30.3192 8.4768 1.48749 70.44 33 -25.0442 0.3000 34 -24.2369 1.4000 1.85000 27.03 35 126.1017 0.3000 36 56.2183 8.8458 1.51680 64.20 37 -34.9385 0.3000 38 91.0048 9.4258 1.51680 64.20 39 -32.3162 0.3000 40 -31.2081 1.7000 1.90366 31.32 41 66.4886 1.1482 42 87.3191 7.9639 1.92286 20.88 43 -63.5414 (variable) 44 110.7482 4.8121 1.92286 20.88 45 -370.6516 8.0000 46 ∞ 40.0000 1.51680 64.20 47∞8.0000 48 ∞ 1.8000 1.51680 64.20 49∞0.3000 Image plane ∞.

[0029] Variable Data Zoom position Wide-angle end Telephoto end D16 4.6079 2.4706 D18 6.6580 5.2092 D22 36.8775 7.2016 D24 23.2618 45.2999 D29 2.5879 0.3000 D43 0.3000 13.8119.

[0030] "Aspheric data" The aspheric data is shown below. Side 7 K=-1.33729E+00 A3=-2.98520E-04 A4=2.01671E-06 A5=9.93713E-08 A6=-5.64627E-10 A7=-2.93961E-11 A8=7.86589E-14 A9=1.24782E-14 A10=-2.57518E-17 A11=-4.25264E-18 A12=4.58537E-20.

[0031] Side 8 K=-9.08151E-01 A3=-3.35969E-04 A4=-1.11565E-06 A5=1.51432E-08 A6=6.76716E-10 A7=-5.76814E-13 A8=-1.97260E-13 A9=-2.34787E-15 A10=2.45628E-17 A11=-3.83930E-19 A12=9.14408E-21.

[0032] Page 13 K=3.41293E-01 A4=-2.88371E-06 A6=1.63989E-08 A8=-2.85337E-11 A10=2.29519E-14 A12=-7.41080E-18.

[0033] Side 14 K=4.06963E-01 A4=3.54854E-07 A6=1.69297E-08 A8=-2.60960E-11 A10=1.36613E-14 A12=-1.04654E-18.

[0034] In the above notation, for example, "-1.04654E-18" is "-1.04654×10 -18 " The same applies below.

[0035] "Various Data" Focal length: 10.710 F-number: 1.81 Half angle of view: 56.92° Image height: 16.60 BF:43.858 Lens length: 343.858 "Parameter value of the conditional expression" (1) |f1 / fw|= 0.777 (2) Bf / fw = 4.095 (3)f SG4 / f1 = 2.797 (4)ν G7L = 20.88 (5)θ gF -(0.6438-0.001682ν G7L ) = 0.0283 "Focal length values ​​of lens groups and sub-lens groups" First lens group: -8.323 Second lens group: 72.946 Third lens group: 100.256 4th lens group: 130.168 Fifth lens group: 1718.462 6th lens group: 186.982 7th lens group: 92.843 First sub-lens group: -97.418 Second sub-lens group: -100.357 3rd sub-lens group: 523.641 4th sub-lens group: -23.277.

[0036] FIG. 2 shows the spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 1, and FIG. 3 shows the coma aberration. Each aberration diagram shows the aberration of green light with a wavelength of 550 nm, but the spherical aberration diagram and coma aberration diagram also show the aberration of wavelengths of 610 nm and 460 nm representing red and blue light. In the astigmatism diagram, S indicates the aberration of the sagittal image, and M indicates the aberration of the meridional image. FIG. 4 shows the spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens of Example 1, and FIG. 5 shows the coma aberration.

[0037] "Example 2" The projection zoom lens of Example 2 is a specific example of the embodiment shown in FIG.

[0038] The focal lengths of the first lens group G1 and the fifth lens group G5 are negative values, and the focal lengths of the other lens groups are positive values. That is, the refractive power distribution of the first lens group G1 to the seventh lens group G7 from the enlargement side to the reduction side is "negative-positive-positive-positive-negative-positive-positive." The first lens group G1 is composed of a first sub-lens group SG1 consisting of three negative lenses from the magnification side, a second sub-lens group SG2 consisting of one aspherical lens, a third sub-lens group SG3 consisting of one positive lens with a large curvature on the magnification side, and a fourth sub-lens group SG4 consisting of two negative lenses: a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the magnification side. The aperture stop S is located near the enlargement side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. The projection zoom lens of Example 2 is located at a distance of 875 mm from the screen, and has a half angle of view of 60.05° at the wide-angle end, which is the largest among all the Examples, making it an example capable of projecting a large image at a short projection distance (875 mm). The zoom ratio of the projection zoom lens of Example 2 is 1.25, and the data at the wide-angle end and the telephoto end are shown below.

[0039] "Example 2 Data" Surface number RD Nd νd Material surface ∞ 875.0000 1 114.2564 7.0000 1.80420 46.50 2 86.7870 15.2101 3 113.0737 5.9000 1.80420 46.50 4 70.5935 15.6298 5 103.1576 5.0000 1.80420 46.50 6 58.3268 11.8274 7* 35.6512 5.0000 1.50966 56.38 8* 20.0129 5.7210 9 55.1795 7.4000 1.84666 23.78 10 57.6192 34.4823 11* -112.7043 2.1000 1.76802 49.24 12* 58.3875 16.7576 13 -35.7465 2.3000 1.49700 81.61 14 117.3805 (variable) 15 313.9302 12.8954 1.67270 32.17 16 -54.3085 (variable) 17 94.1162 13.0000 1.85883 30.00 18 -85.7633 0.3000 19 -83.5821 2.3000 1.92286 20.88 20 -519.9618 (variable) 21 81.2443 11.5000 1.51823 58.96 22 -203.8254 (variable) 23(Aperture) ∞ 3.6194 24 -47.2072 1.2000 1.95375 32.32 25 186.4361 0.3000 26 49.0535 4.0488 1.59270 35.31 27 -48.7394 (variable) 28 262.1440 1.3000 1.95375 32.32 29 31.1099 0.3000 30 28.4378 8.4764 1.48749 70.44 31 -19.7491 0.3000 32 -19.0237 1.4000 1.85000 27.03 33 274.3982 0.3000 34 52.1440 8.1802 1.51680 64.20 35 -44.2492 0.5540 36* 72.8754 11.8287 1.51680 64.20 37* -22.7716 0.3000 38 -31.5577 1.7000 1.90366 31.32 39 59.3415 0.9681 40 74.6406 7.4305 1.92286 20.88 41 -77.8480 (variable) 42 87.6344 5.7596 1.92286 20.88 43 -309.3316 2.4000 44 ∞ 40.0000 1.51680 64.20 45∞8.0000 46 ∞ 1.8000 1.51680 64.20 47 ∞ 0.3000 Image plane ∞.

[0040] Variable Data Zoom position Wide-angle end Telephoto end D14 5.1913 3.0000 D16 2.4000 0.8000 D20 32.4262 7.8245 D22 22.2151 40.9821 D27 3.0000 0.3000 D41 0.3000 12.6261 "Aspheric data" Side 7 K=-8.28708E-01 A3=-3.91008E-04 A4= 4.11383E-06 A5=8.18843E-08 A6=-1.25439E-09 A7=-3.11485E-11 A8=3.76981E-13 A9=1.30745E-14 A10=-4.99894E-17 A11=-6.07135E-18 A12=7.30538E-20.

[0041] Side 8 K=-9.14449E-01 A3=-4.40540E-04 A4 = 5.65517E-07 A5 = -9.34587E-10 A6 = 6.98968E-11 A7 = -7.67535E-13 A8 = -1.43622E-13 A9 = 1.03285E-15 A10 = 3.17970E-17 A11 = -1.35325E-19 A12 = -6.70057E-21 。

[0042] Sheet 11 K = 7.35991E+00 A4 = -4.70014E-06 A6 = 1.90193E-08 A8 = -2.76771E-11 A10 = 2.03347E-14 A12 = -6.02086E-18 。

[0043] Sheet 12 K = -1.87771E+00 A4 = -6.75329E-07 A6 = 1.89144E-08 A8 = -2.68160E-11 A10 = 1.34771E-14 A12 = -1.91097E-18 。

[0044] Sheet 36 K = 8.34376E-02 A4 = -1.36052E-06 A6 = 9.63073E-10 A8 = 8.33254E-13 A10 = -1.19787E-14 A12 = 3.29413E-17 。

[0045] Sheet 37 K = -5.87064E-01 A4 = 4.34076E-06 A6 = 5.94229E-09 A8=2.71312E-12 A10=-5.01458E-16 A12=2.56581E-17.

[0046] "Various Data" Focal length: 9.504 F-number: 2.01 Half angle of view: 60.05° Image height: 16.60 BF:38.258 Total lens length: 336.080.

[0047] "Parameter value of the conditional expression" (1) |f1 / fw| = 0.785 (2) Bf / fw = 4.025 (3)f SG4 / f1 = 2.997 (4)ν G7L = 20.88 (5)θ gF -(0.6438-0.001682ν G7L ) = 0.0283.

[0048] "Focal length values ​​of lens groups and sub-lens groups" First lens group: -7.462 Second lens group: 69.809 Third lens group: 101.430 4th lens group: 113.658 Fifth lens group: -3998.133 6th lens group: 215.434 7th lens group: 75.515 First sub-lens group: -80.254 Second sub-lens group: -100.350 3rd sub-lens group: 643.849 4th sub-lens group: -22.365.

[0049] FIG. 7 shows the spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 2, and FIG. 8 shows the coma aberration. FIG. 9 shows the spherical aberration, astigmatism, and distortion at the telephoto end, and FIG. 10 shows the coma aberration.

[0050] "Example 3" Example 3 is a specific example of the embodiment shown in FIG. The focal lengths of the first lens group G1 and the fifth lens group are negative values, and the focal lengths of the other lens groups are positive values.

[0051] That is, the refractive power distribution of the first lens group G1 to the seventh lens group G7 from the enlargement side to the reduction side is "negative-positive-positive-positive-negative-positive-positive." The first lens group G1 is composed of, from the magnification side, a first sub-lens group SG1 consisting of two negative lenses, a second sub-lens group SG2 consisting of one aspherical lens, a third sub-lens group SG3 consisting of one positive lens with a large curvature on the magnification side and one negative lens, and a fourth sub-lens group SG4 consisting of two negative lenses: a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the magnification side. The aperture stop S is located near the enlargement side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming.

[0052] The zoom ratio of the projection zoom lens of Example 3 is 1.37, and data in two modes, the wide-angle end and the telephoto end, are shown below.

[0053] "Example 3 Data" Surface number RD Nd νd Object surface ∞ 1034.3000 1 119.8024 5.9000 1.81600 46.62 2 74.2351 11.2296 3 91.9194 5.0000 1.80420 46.50 4 63.9108 8.0709 5* 36.7715 5.0000 1.50966 56.38 6* 21.2635 22.5574 7 52.1137 13.5223 1.80518 25.46 8 102.4484 8.9327 9 1427.8019 3.7000 1.90265 35.77 10 94.2476 14.7305 11* -234.4954 2.1000 1.76802 49.24 12* 54.4328 20.1321 13 -32.1327 2.3000 1.49700 81.61 14 290.1122 (variable) 15 1113.8730 10.9197 1.67270 32.17 16 -53.2224 (variable) 17 188.8129 10.0945 1.85883 30.00 18 -69.0317 0.3000 19 -68.0432 2.3000 1.92286 20.88 20 -187.6810 (variable) 21 74.0340 7.3891 1.51823 58.96 22 -268.6350 (variable) 23(Aperture) ∞ 2.0115 24 -51.4529 1.2000 1.95375 32.32 25 233.5927 0.3000 26 73.5465 6.2344 1.59270 35.31 27 -49.2612 (variable) 28 85.3651 1.3000 1.95375 32.32 29 32.8758 0.3000 30 33.3405 10.0000 1.48749 70.44 31 -30.9268 0.3823 32 -29.1640 1.4000 1.85000 27.03 33 172.8588 2.8157 34 74.9676 13.0000 1.51680 64.20 35 -40.8580 0.3000 36 70.4662 11.7198 1.51680 64.20 37 -42.3209 0.3122 38 -40.8225 1.7000 1.90366 31.32 39 100.5658 2.9826 40 192.1830 6.1582 1.92286 20.88 41 -96.6835 (variable) 42 112.7454 4.9247 1.94595 17.98 43 -454.6431 8.3000 44 ∞ 40.0000 1.51680 64.20 45∞8.5000 46 ∞ 1.8000 1.51680 64.20 47∞0.0000 48∞0.3000 Image plane ∞.

[0054] Variable Data Zoom position Wide-angle end Telephoto end D14 4.0011 2.5000 D16 7.5853 0.4060 D20 35.7326 6.7753 D22 27.5796 47.1696 D27 3.2813 0.3000 D41 0.3000 21.3290.

[0055] "Aspheric data" 5th page K=-1.98362E+00 A3=-1.47590E-04 A4=-2.05000E-06 A5=1.36818E-07 A6 = -4.33329E-10 A7 = -2.40245E-11 A8 = 2.39741E-14 A9 = 5.66590E-15 A10 = 1.39420E-17 A11 = -1.70796E-18 A12 = 1.52793E-20 。

[0056] Face 6 K = -1.09573E+00 A3 = -1.78677E-04 A4 = -2.90543E-06 A5 = 5.39752E-08 A6 = 1.04366E-09 A7 = -3.88317E-12 A8 = -2.75365E-13 A9 = -2.77538E-15 A10 = -3.49779E-18 A11 = 2.71886E-19 A12 = 1.07696E-20 。

[0057] Face 11 K = 1.00093E+01 A4 = -5.06980E-06 A6 = 1.45115E-08 A8 = -2.07361E-11 A10 = 1.58348E-14 A12 = -5.04367E-18 。

[0058] Face 12 K = -2.44995E-01 A4 = -3.05244E-06 A6 = 1.61618E-08 A8 = -2.15732E-11 A10 = 1.45196E-14 A12 = -2.81763E-18 。

[0059] "Various Data" Focal length: 12.978 F-number: 1.82 Half angle of view: 51.37° Image height: 16.60 BF:44.658 Total lens length: 344.358.

[0060] "Parameter value of the conditional expression" (1) |f1 / fw| = 0.766 (2) Bf / fw = 3.441 (3)f SG4 / f1 = 2.463 (4)ν G7L = 17.98 (5)θ gF -(0.6438-0.001682ν G7L ) = 0.0386.

[0061] "Focal length values ​​of lens groups and sub-lens groups" First lens group: -9.945 Second lens group: 75.795 Third lens group: 120.877 4th lens group: 112.825 Fifth lens group: -654.137 6th lens group: 176.397 7th lens group: 95.909 First sub-lens group: -130.174 Second sub-lens group: -111.009 3rd sub-lens group: 695.486 4th sub-lens group: -24.498.

[0062] FIG. 12 shows the spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 3, and FIG. 13 shows the coma aberration. FIG. 14 shows the spherical aberration, astigmatism, and distortion at the telephoto end, and FIG. 15 shows the coma aberration.

[0063] "Example 4" Example 4 is a specific example of the embodiment shown in FIG. The focal lengths of the first lens group G1 and the fifth lens group are negative values, and the focal lengths of the other lens groups are positive values. That is, the refractive power distribution of the first lens group G1 to the seventh lens group G7 from the enlargement side to the reduction side is "negative-positive-positive-positive-negative-positive-positive." The first lens group G1 is composed of, from the magnification side, a first sub-lens group SG1 consisting of two negative lenses, a second sub-lens group SG2 consisting of one aspherical lens, a third sub-lens group SG3 consisting of one positive lens with a large curvature on the magnification side and one negative lens, and a fourth sub-lens group SG4 consisting of two negative lenses: a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the magnification side. The aperture stop S is located near the enlargement side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. The zoom ratio of the projection zoom lens of Example 4 is 1.44, and data in two modes, the wide-angle end and the telephoto end, are shown below.

[0064] "Example 4 Data" Surface number RD Nd νd Object surface ∞ 1114.0000 1 97.8067 5.9000 1.80420 46.50 2 68.4130 7.2167 3 78.0614 5.0000 1.80420 46.50 4 60.3865 8.0071 5* 38.0071 5.0000 1.50966 56.38 6* 24.0506 11.1978 7 55.9076 6.8329 1.80518 25.46 8 63.8518 27.0769 9 -112.5542 3.7000 1.84666 23.78 10 -194.4890 27.7082 11 -96.4387 2.1000 1.48749 70.44 12 51.1283 12.9675 13 -30.8516 2.3000 1.65844 50.85 14 215.3601 (variable) 15 1252.7139 10.6949 1.67270 32.17 16 -46.2844 (variable) 17 170.4038 10.9473 1.85883 30.00 18 -63.7500 0.3000 19 -62.6445 2.3000 1.92286 20.88 20 -141.5098 (variable) 21 69.5650 7.0493 1.51823 58.96 22 -262.9560 (variable) 23(Aperture) ∞ 1.7957 24 -96.5537 1.2000 1.95375 32.32 25 119.2483 3.0995 26 58.5439 5.9826 1.59270 35.31 27 -142.9895 (variable) 28 74.4842 1.3000 1.95375 32.32 29 32.5847 0.3000 30 30.6412 10.0000 1.48749 70.44 31 -52.1368 3.3920 32 -36.5861 1.4000 1.85000 27.03 33 77.2635 0.3000 34 49.8619 12.2513 1.51680 64.20 35 -44.8865 1.1617 36* 67.6628 12.2658 1.51680 64.20 37* -35.9270 0.3000 38 -37.2406 1.7000 1.90366 31.32 39 65.0837 0.4285 40 70.9886 8.6683 1.92286 20.88 41 -94.1737 (variable) 42 142.8087 3.7276 1.94595 17.98 43 -1633.7083 8.3000 44 ∞ 40.0000 1.51680 64.20 45∞8.5000 46 ∞ 1.8000 1.51680 64.20 47 ∞ 0.3000 Image plane ∞.

[0065] Variable Data Zoom position Wide-angle end Telephoto end D14 5.0000 2.5000 D16 7.6045 0.3000 D20 34.8597 4.7117 D22 8.1032 34.4418 D27 18.1041 8.6985 D41 0.4571 23.4765.

[0066] "Aspheric data" 5th page K=-2.17458E+00 A3=-9.87344E-05 A4=-2.53423E-06 A5=1.25334E-07 A6=3.03769E-10 A7=-3.73891E-11 A8=5.07049E-14 A9=7.45860E-15 A10=3.67596E-17 A11=-3.23629E-18 A12=3.08003E-20.

[0067] Side 6 K=-1.15707E+00 A3=-1.23828E-04 A4=-3.33259E-06 A5=1.02953E-07 A6=5.38483E-10 A7=-8.42031E-12 A8=-1.95662E-13 A9=-9.96765E-16 A10=-2.32049E-17 A11=-9.59122E-19 A12=1.52464E-20.

[0068] Page 36 K=1.06450E+00 A4=-4.17787E-07 A6=-6.97029E-10 A8=2.46707E-12 A10=-8.15060E-15 A12=4.95906E-18.

[0069] Page 37 K=-3.27951E-01 A4=6.30516E-07 A6=-3.29516E-10 A8=6.80144E-12 A10=-1.64485E-14 A12=1.74034E-17.

[0070] "Various Data" Focal length; 15.947 F-number: 1.82 Half angle of view: 45.82° Image height: 16.60 BF:44.658 Lens length: 344.358 "Parameter value of the conditional expression" (1) |f1 / fw| = 0.593 (2) Bf / fw = 2.8 (3)f SG4 / f1 = 2.399 (4)ν G7L = 17.98 (5)θ gF -(0.6438-0.001682ν G7L ) = 0.0386.

[0071] "Focal length values ​​of lens groups and sub-lens groups" First lens group: -9.463 Second lens group: 66.573 Third lens group: 98.428 4th lens group: 106.927 Fifth lens group: -375.339 6th lens group: 154.673 7th lens group: 138.975 First sub-lens group: -167.761 Second sub-lens group: -146.190 3rd sub-lens group: -3728.072 4th sub-lens group: -22.707 FIG. 17 shows the spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 4, and FIG. 18 shows the coma aberration. FIG. 19 shows spherical aberration, astigmatism, and distortion at the telephoto end, and FIG. 20 shows coma aberration.

[0072] "Example 5" Example 5 is a specific example of the embodiment shown in FIG. The focal lengths of the first lens group G1 and the fifth lens group are negative values, and the focal lengths of the other lens groups are positive values. That is, the refractive power distribution of the first lens group G1 to the seventh lens group G7 from the enlargement side to the reduction side is "negative-positive-positive-positive-negative-positive-positive." The first lens group G1 is composed of, from the magnification side, a first sub-lens group SG1 consisting of two negative lenses, a second sub-lens group SG2 consisting of one aspherical lens, a third sub-lens group SG3 consisting of one positive lens with a large curvature on the magnification side and one negative lens, and a fourth sub-lens group SG4 consisting of two negative lenses: a negative lens with a large curvature on the reduction side and a negative lens with a large curvature on the magnification side. An aperture stop S is disposed between the lenses in the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. The zoom ratio of the projection zoom lens of Example 5 is 1.44, and data in two modes, the wide-angle end and the telephoto end, are shown below.

[0073] "Example 5 Data" Surface number RD Nd νd Object surface ∞ 1096.6000 1 110.2665 5.9000 1.80420 46.50 2 73.2141 6.6403 3 81.6111 5.0000 1.80420 46.50 4 65.6098 1.8335 5* 24.4612 5.0000 1.50966 56.38 6* 17.8204 35.8942 7 50.6701 12.3092 1.84666 23.78 8 90.1710 9.6159 9 459.8740 3.7000 1.78800 47.37 10 58.1394 7.1241 11 141.1640 2.1000 1.51680 64.20 12 38.9708 16.6541 13 -38.9104 2.3000 1.48749 70.44 14 87.6107 (variable) 15 251.9217 12.9890 1.67270 32.17 16 -92.6733 (variable) 17 192.9651 9.5903 1.85883 30.00 18 -76.4813 0.5086 19 -74.3535 2.3000 1.92286 20.88 20 -187.7919 (variable) 21 72.0250 6.9849 1.51823 58.96 22 -253.8695 (variable) 23 -73.8222 1.2000 1.95375 32.32 24 101.3042 1.1693 25(Aperture) ∞ 6.8056 26 65.3342 6.6474 1.59270 35.31 27 -75.3557 (variable) 28 81.1648 1.3000 1.95375 32.32 29 34.4223 0.3000 30 34.7885 10.0000 1.51680 64.20 31 -35.6332 0.5016 32 -34.0607 1.4000 1.85000 27.03 33 123.6494 0.6932 34 60.2249 10.9009 1.51680 64.20 35 -50.5648 5.3323 36 115.3225 11.6694 1.51680 64.20 37 -38.3518 0.3311 38 -37.1086 1.7000 1.90366 31.32 39 71.9038 0.8798 40 83.2653 8.8976 1.92286 20.88 41 -83.0964 (variable) 42 122.5644 4.6096 1.94595 17.98 43 -794.5508 8.3000 44 ∞ 40.0000 1.51680 64.20 45∞8.5000 46 ∞ 1.8000 1.51680 64.20 47 ∞ 0.3000 Image plane ∞.

[0074] Variable Data Zoom position Wide-angle end Telephoto end D14 15.4201 8.4407 D16 7.3760 2.7967 D20 36.2295 6.6242 D22 12.3942 37.8953 D27 7.1983 1.1090 D41 0.3000 22.0522.

[0075] "Aspheric data" 5th page K=-2.12413E+00 A3=-1.05805E-04 A4=-2.53345E-06 A5=8.71858E-08 A6=5.34309E-10 A7=1.66214E-11 A8=-1.42180E-12 A9=1.69131E-14 A10=6.87506E-17 A11=-2.25042E-18 A12=1.13503E-20.

[0076] Side 6 K=-1.49738E+00 A3=-1.57596E-04 A4=-2.18056E-06 A5=1.50267E-07 A6=-1.12413E-09 A7=9.20968E-12 A8=-1.58481E-13 A9=-8.29869E-15 A10=4.87287E-17 A11=2.03299E-18 A12=-1.70970E-20.

[0077] "Various Data" Focal length: 15.705 F-number: 1.82 Half angle of view: 46.06° Image height: 16.60 BF:44.658 Total lens length: 344.358.

[0078] "Parameter value of the conditional expression" (1) |f1 / fw| = 0.962 (2) Bf / fw = 2.844 (3)f SG4 / f1 = 2.162 (4)ν G7L = 17.98 (5)θ gF -(0.6438-0.001682ν G7L ) = 0.0386.

[0079] "Focal length values ​​of lens groups and sub-lens groups" First lens group: -15.112 Second lens group: 102.264 Third lens group: 122.915 4th lens group: 109.064 Fifth lens group: -518.599 6th lens group: 167.201 7th lens group: 112.527 First sub-lens group: -178.196 Second sub-lens group: -172.688 3rd sub-lens group: -1075.418 4th sub-lens group: -32.666.

[0080] FIG. 22 shows the spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens of Example 5, and FIG. 23 shows the coma aberration. FIG. 24 shows spherical aberration, astigmatism, and distortion at the telephoto end, and FIG. 25 shows coma aberration.

[0081] FIG. 26 shows the spherical aberration, astigmatism, and distortion when the projection zoom of Example 1 of Examples 1 to 5 described above is zoomed to the wide-angle end and focused at a projection distance of 800 mm, and FIG. 27 shows the coma aberration.

[0082] "Variable data on focusing" Projection distance 1000mm 800mm D6 12.4909 11.7838 D8 6.1303 5.7567 D12 18.5934 19.6741.

[0083] When the projection distance is shortened from 1000 mm to 800 mm, the second sub-lens group SG2 in the first lens group G1 moves 0.7071 mm and the third sub-lens group SG3 moves 1.0807 mm toward the enlargement side on the optical axis, thereby achieving a good image.

[0084] As described above, all of the projection zoom lenses of Examples 1 to 5 have a large half angle of view of 45 degrees to 60 degrees at the wide-angle end, a small F-number of 2 or less, and can realize a wide-angle, bright projected image that can be viewed on a large screen even at a short projection distance.

[0085] In the above-mentioned first to fifth embodiments, the second lens group G2 to the sixth lens group G6 constituting the moving group are moved independently in the optical axis direction for zooming, but the movement of each of these lens groups does not necessarily have to be independent. For example, the second lens group G2 and the third lens group G3, or the fifth lens group G5 and the sixth lens group G6 can be moved in conjunction with each other.

[0086] A projection type image display device and an image pickup device using the projection zoom lens of the present invention will be briefly described below.

[0087] FIG. 28 is an explanatory diagram showing one embodiment of the "projector." A projection zoom lens PZL, image generating devices ISR, ISB, and ISG that use “image display elements” such as DMDs, and a color synthesis prism P are loaded inside a casing 1 of the projector body. The image generating device ISR displays a “red component image” of the color image to be projected on an image display element, generates “red image light LR”, and emits it towards the color synthesis prism P. The image generating device ISG displays a "green component image" of a color image on a display device, generates "green image light LG", and emits it toward the color synthesis prism P. What has been described as the image display surface MD in Figure 1 and other figures is the image display surface of the image generating device ISG. The image generating device ISB displays a “blue component image” of a color image on a display device, generates “blue image light LB”, and emits it toward the color synthesis prism P.

[0088] The color synthesis prism P synthesizes the red component image light LR, the green component image light LG, and the blue component image light LB to generate "color image light IML" and causes it to enter the projection zoom lens PZL. The projection zoom lens PZL radiates the incoming color image light IML as projection imaging light PRL toward a screen. As the projection zoom lens PZL, any one of the lenses described in claims 1 to 12, specifically any one of the lenses described in Examples 1 to 5, is used.

[0089] In the projector configuration of Figure 28, if an area sensor is placed at the position of the image generating devices ISR, ISB, and ISG so that its light receiving surface is aligned with the image display surface of these devices and the image formed by the projection zoom lens PZL is captured, a normal camera device can be configured as the "imaging device."

[0090] Fig. 29 is an explanatory diagram showing another embodiment of the "imaging device." To avoid complication, the same reference numerals as in Fig. 28 are used for those parts that are unlikely to be confused, and the above explanation of Fig. 28 is applied to these parts. 29, the symbol HM denotes a "half mirror" and the symbol LR denotes a color image sensor. The color image light IML combined by the color combining prism P passes through the half mirror HM and enters the projection zoom lens PZL, and is focused as an enlarged image on a display surface such as a screen (not shown). The light reflected from the display surface enters the projection zoom lens PZL from the enlargement side, becomes a reduced image forming light beam RIMLA, enters the half mirror HM and is reflected, becomes a reduced image forming light beam RIMLB, and enters the image sensor LR. The light receiving surface of the image sensor LR is located on a plane optically equivalent to the image display surface of the image generating device ISR, etc., and corresponds to the "conjugate plane of the projection zoom lens" with respect to the display surface.

[0091] With this configuration, the enlarged projection image displayed on the display surface or the "image additionally displayed on the display surface" can be captured by the image sensor LR. The image sensor LR may be a "color image sensor" or a "monochrome image sensor." If a color image sensor is used, a color image of the enlarged projection image can be captured. If a monochrome image sensor is used, a monochrome image of the enlarged projection image can be captured. The half mirror HM and the image sensor LR may be fixedly provided at the positions shown in Fig. 29, but the half mirror HM and the image sensor LR may be displaceable as a unit so that the half mirror HM is retracted outside the imaging light beam when imaging is not being performed. Alternatively, only the half mirror HM may be movable so that it can be moved in and out of the imaging light beam from the projection zoom lens PZL and positioned in the imaging light beam only when imaging is being performed. When the light enters or leaves the half-mirror imaging light beam, the change in the conjugate distance that accompanies the entrance or exit is adjusted by adjusting the positional relationship between the image generating device on the light source side and the projection zoom lens PZL.

[0092] Although a preferred embodiment of the invention has been described above, the invention is not limited to the specific embodiment described above, and various modifications and variations are possible within the spirit of the invention described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely a list of preferred effects resulting from the invention, and the effects of the invention are not limited to "those described in the embodiments." [Explanation of symbols]

[0093] G1 First 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 SG1 First sub-lens group SG2 Second sub-lens group SG3 Third sub-lens group SG4 4th sub-lens group P Color synthesis prism (color synthesis optical system) MD image display surface CG cover glass [Prior art documents] [Patent documents]

[0094] [Patent Document 1] JP 2010-237605 A [Patent Document 2] JP 2016-050990 A [Patent Document 3] JP2019-211713 Public Relations

Claims

1. The optical system comprises, in order from the enlargement side to the reduction 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 positive refractive power, a fifth lens group having positive or negative refractive power, a sixth lens group having positive refractive power, and a seventh lens group having positive refractive power. During zooming, the first lens group and the seventh lens group are fixed, and the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group each move in the optical axis direction while changing an interval between each of the second lens group and an adjacent lens group, the first lens group is composed of, in order from the enlargement side to the reduction side, a first sub-lens group having negative refractive power, a second sub-lens group consisting of one aspheric lens, a third sub-lens group having a positive lens having a large curvature on the enlargement side, and a fourth sub-lens group having negative refractive power, and during focusing, the second sub-lens group and the third sub-lens group move on the optical axis, The focal length of the entire system at the wide-angle end is fw, and the focal length of the first lens group is f1, and the conditions are as follows: (1) 0.5 <|f1 / fw|< 1.0 A projection zoom lens that satisfies the above requirements.

2. 2. The projection zoom lens according to claim 1, The back focus in air: Bf, and the focal length of the entire system at the wide-angle end: fw are set under the following conditions: (2) 1.0 < Bf / fw < 5.0 A projection zoom lens that satisfies the above requirements.

3. 3. The projection zoom lens according to claim 1, an aperture stop is disposed in the fifth lens group, and displaces integrally with the fifth lens group when the fifth lens group moves during zooming;

4. 4. A projection zoom lens according to claim 1, A projection zoom lens in which the first sub-lens group is composed entirely of negative lenses.

5. A projection zoom lens according to any one of claims 1 to 4, The aspheric lens of the second sub-lens group is made of plastic.

6. 6. A projection zoom lens according to claim 1, The fourth sub-lens group is a projection zoom lens configured by arranging, in order from the enlargement side, a negative lens having a large curvature on the reduction side and a negative lens having a large curvature on the enlargement side.

7. 7. A projection zoom lens according to claim 1, The fourth sub-lens group has the strongest negative refractive power among the four sub-lens groups constituting the first lens group, and the focal length of the first lens group: f1 and the focal length of the fourth sub-lens group: fSG4 satisfy the condition: (3) 1.5 < fSG4 / f1 < 3.5 A projection zoom lens characterized by satisfying the following:

8. 8. A projection zoom lens according to claim 1, The second lens group is composed of one positive lens.

9. 9. A projection zoom lens according to claim 1, A projection zoom lens, wherein the fourth lens group is composed of one positive lens.

10. 10. A projection zoom lens according to claim 1, The seventh lens group is composed of one positive lens, and the Abbe number: νG7L and the partial dispersion ratio: θgF of the material of the positive lens satisfy the following conditions: (4) νG7L < 35 (5) 0.0005< θgF-(0.6438-0.001682νG7L) A projection zoom lens that satisfies the above requirements.

11. 11. A projection zoom lens according to any one of claims 1 to 10, A projection zoom lens is a telecentric optical system in which the entrance pupil position on the reduction side is located almost at infinity.

12. 12. A projection type image display device comprising the projection zoom lens according to claim 1.

Images