JP2003287679A - Zoom lens and camera device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a high-performance zoom lens capable of realizing resolving power coping with an imaging device whose number of pixels is 3,000,000 to 5,000,000 though it is compact and has the wide angle of view. <P>SOLUTION: The zoom lens is constituted by arranging a 1st group I having a negative focal distance, a 2nd group II having a positive focal distance and a 3rd group III having a positive focal distance in order from an object side, and providing a diaphragm S moving integrally with the 2nd group on the object side of the 2nd group. In the case of varying power from a short focal end to a long focal end, the 2nd group moves monotonously from an image side to the object side and the 1st group moves to correct the fluctuation of the position of an image surface associated with varying power. The 2nd group II has a compound lens consisting of three lenses, that is, a negative lens, a positive lens and a negative lens in order from the object side. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens and a camera device. The zoom lens of the present invention can be suitably used as a zoom photographing lens used in a silver halide camera, and can also be particularly suitably used in a digital camera, a video camera, and a portable information terminal device with a built-in digital camera function.

[0002]

2. Description of the Related Art Recently, the market of digital cameras has become very large. Although there are various requests from users for digital cameras, high image quality and miniaturization are always desired by users, and there is a great demand, and zoom lenses used as photographing lenses are required to have both high performance and miniaturization. The zoom lens used in a digital camera requires a reduction in the total lens length (distance from the lens surface closest to the object side to the image surface) in terms of downsizing, and at least 3 million to 500 in terms of high performance. It is necessary to have a resolving power over the "entire zoom range" that can be applied to an image sensor of 10,000 pixels. Many users desire a wide angle of view of the taking lens, and it is desirable that the half angle of view of the short focus end of the sume lens is 38 degrees or more. The half angle of view: 38 degrees corresponds to a focal length of 28 mm in terms of a 35 mm silver salt camera (so-called Leica version).

Many types of zoom lenses for digital cameras are conceivable. As types suitable for miniaturization, there are "a first group having a negative focal length and a second group having a positive focal length in order from the object side". And a third lens unit having a positive focal length is arranged, and an aperture stop that moves integrally with the second lens unit is provided on the object side of the second lens unit, and upon zooming from the short focal length end to the long focal length end, Second
There is one in which the group moves monotonously from the image side to the object side, and the first group moves so as to “correct the fluctuation of the image plane position due to zooming” (for example, Japanese Patent Laid-Open No. 10-039214, Kaihei 10-104518, JP 2001-2964.
No. 75, etc.).

The zoom lens disclosed in Japanese Unexamined Patent Publication No. 10-039214 is the basic one of this type of zoom lens, and although the basic structure is disclosed in the same publication, the aspect of miniaturization. But there is still room for improvement.

The zoom lens disclosed in Japanese Unexamined Patent Publication No. 10-104518 considers the prevention of decentering at the time of assembly by using a cemented lens.
It is not always sufficient to support an image sensor having 3 to 5 million pixels.

The zoom lens disclosed in Japanese Unexamined Patent Application Publication No. 2001-2964752 is relatively small and has better image performance than the above-mentioned one, but the half angle of view remains at about 33 degrees.
It is hard to say that it has a wide angle of view.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a small size and a wide angle of view, but it is 3,000,000 to 5,000,000.
It is an object to realize a high-performance zoom lens that can realize a resolution corresponding to an image pickup device of, 000,000 pixels.

Another object of the present invention is to realize a compact and high-quality camera device (such as a portable information terminal device) using the above zoom lens as a photographing optical system of a camera function section.

[0009]

As shown in FIG. 1, a zoom lens system according to the present invention includes a first group I having a negative focal length and a positive focus in order from the object side (left side in FIG. 1). A second lens group II having a distance and a third lens group III having a positive focal length are arranged, and an aperture stop S that moves integrally with the second lens group II is provided on the object side of the second lens group II. Upon zooming from the edge to the long focus edge, the second lens unit II monotonously moves from the image side to the object side,
In the zoom lens in which the first group I moves so as to correct the fluctuation of the image plane position due to zooming, the second group II includes a triplet cemented lens including a negative lens, a positive lens, and a negative lens in order from the object side. “Having” (claim 1).

The zoom lens according to claim 1 is the second lens unit I.
The negative lens disposed closest to the object side of the I cemented triplet lens may have a "meniscus shape with a concave surface facing the image side" (claim 2).

The zoom lens according to the first or second aspect is
The negative lens arranged closest to the image side of the triplet cemented lens of the second group II can be "a lens having a strong concave surface facing the image side" (claim 3).

In the zoom lens according to the first, second or third aspect of the present invention, the refractive index of the positive lens arranged in the middle of the third cemented lens of the second group II is N _C2 , the Abbe number is ν _C2 , and the condition is: It is preferable that 1) 1.45 <N _C2 <1.52 (2) 68 <ν _C2 <85 be satisfied (claim 4).

In this case, the refractive index of the negative lens arranged closest to the object side in the three-lens cemented lens of the second lens group II: N
_C1 , Abbe number: ν _C1 , the refractive index of the negative lens arranged closest to the image side of the third cemented lens in the second group: N _C3 , Abbe number: ν _C3 are conditions: (3) 1.75 <N _C1 <1.95 (4) 20 <ν _C1 <35 (5) 1.60 <N _C3 <1.95 (6) It is preferable to satisfy 20 <ν _C3 <40 (claim 5).

The zoom lens according to any one of claims 1 to 5 is the radius of curvature of the cemented surface on the object side of the triplet cemented lens of the second group II: R _C2 and the curvature of the surface closest to the image side. Radius: R
_C4 preferably satisfies the condition: (7) 0.5 <(R _C2 / R _C4 ) <0.85 (claim 6).

In the zoom lens according to any one of claims 1 to 6, the second group can have “at least one positive lens on each of the object side and the image side of the triplet cemented lens” ( Claim 7). In this case, it is preferable that at least one of the positive lenses arranged on the object side and the image side of the triplet cemented lens has an aspherical surface (claim 8).

The camera device of the present invention is characterized by having the zoom lens according to any one of claims 1 to 8 as a "photographing optical system of a camera function section" (claim 9). Such a camera device can be implemented as a "portable information terminal device". It goes without saying that the present invention can also be implemented as a digital camera device or a silver salt camera device that has the zoom lens according to any one of claims 1 to 8 as a photographic optical system.

As in the zoom lens of the present invention, in a zoom lens composed of three groups having negative, positive, and positive power distributions from the object side, in general, when zooming from the short focal end to the long focal end, , The second group moves monotonically from the image side to the object side,
The first group moves so as to “correct the fluctuation of the image plane position due to the magnification change”.

Therefore, the second group bears "most of the zooming function" and the third group is provided "mainly to keep the exit pupil away from the image plane".

In order to realize a zoom lens having various aberrations and high resolving power, it is necessary to suppress aberration fluctuations due to zooming, and in particular, the second zoom lens, which is the main zooming group, is "good in the entire zoom range. Must be corrected for aberrations.

Further, in order to realize a wide angle of view at the short focal end, it is necessary to reduce chromatic aberration of magnification that increases with the widening of the angle of view, and this is satisfactorily corrected in the entire zoom range. Also, the configuration of the second group is important. Conventionally, the second group includes, in order from the object side, a "consisting of three lenses of a positive lens, a negative lens, and a positive lens", a "consisting of three lenses of a positive lens, a positive lens, and a negative lens", a "positive lens,""Consisting of four lenses, positive lens, negative lens, and positive lens", "positive lens,
It is known that “a negative lens, a negative lens, and a positive lens are made up of four elements”, and the like, but the second group of the zoom lens of the present invention can realize an aberration correction capability that exceeds these.

That is, in the zoom lens according to the present invention, the second lens group has a "three cemented lens including a negative lens, a positive lens and a negative lens in order from the object side". Since the two cemented surfaces of the triplet cemented lens have different distances from the diaphragm,
The way of passing rays on and off the axis is also different. Therefore, such a cemented surface of the two surfaces makes it possible to correct axial chromatic aberration and lateral chromatic aberration to some extent independently, and is particularly effective in correcting lateral chromatic aberration that increases as the angle of view becomes wider.

As a measure for providing two cemented surfaces, it is conceivable to use two cemented lenses. However, when the "optical axes of the cemented lenses" are deviated from each other due to decentering at the time of assembly,
Off-axis chromatic aberration of magnification occurs asymmetrically, and unnatural color blur easily occurs.

On the other hand, by using the triplet cemented lens as in the present invention, it is possible to sufficiently reduce the chromatic aberration of magnification without assembling decentering on the two cemented surfaces.

When the “negative lens arranged closest to the object side” of the three-lens cemented lens of the second group has a “meniscus shape with a concave surface facing the image side”, as in the zoom lens according to claim 2, The negative side of the negative lens is a convex surface, which does not significantly refract the incident light to prevent unnecessary aberrations, and the side of the image is a strong concave surface to mainly correct spherical and coma aberrations. Can be corrected to.

As in the zoom lens according to claim 3, the "negative lens arranged closest to the image side" of the doublet cemented lens of the second group is "a lens having a strong concave surface facing the image side". As a result, spherical aberration / coma aberration can be corrected secondarily by the strong concave surface of the image side, and astigmatism can also be corrected, so that even better correction of aberration becomes possible.

The conditions (1) and (2) in claim 4 are conditions for "good chromatic aberration correction", and the refractive index: N
_{When C2} is larger than 1.52 and Abbe number: ν _C2 is smaller than 68, it is difficult to balance axial chromatic aberration with other aberrations, and in particular, axial chromatic aberration is likely to occur at the long focal end. Also, the effect of correcting monochromatic aberration at the cemented surface on the object side cannot be sufficiently obtained.

On the contrary, when the refractive index: N _C2 is smaller than 1.45 and the Abbe number: ν _C2 is larger than 85, it is advantageous for aberration correction, but the glass material becomes expensive and the cost will increase in the future. .

By satisfying the conditions (1) and (2), mainly the axial chromatic aberration can be corrected even better, higher performance can be realized, and an image with high contrast can be obtained.

The conditions (3) to (6) of claim 5 are conditions for correcting the lateral chromatic aberration more favorably. Together with the conditions (1) and (2), the conditions (3) to (6) are satisfied. By satisfying the condition (4), the axial chromatic aberration and the lateral chromatic aberration can be well balanced, and the lateral chromatic aberration can be reduced particularly at the short focus end, and at this time, the correction state of the monochromatic aberration can be maintained well. Therefore, mainly the chromatic aberration of magnification can be corrected more satisfactorily to achieve “higher performance of the zoom lens”.

The condition (7) according to claim 6 is a condition for "further improvement of monochromatic aberration", and the parameter: R
When _{C2 /} R _C4 is greater than 0.85, the spherical aberration at the long focus end is likely largely occurs in the positive direction, it becomes a cause of deterioration of image contrast. On the other hand, if the parameter: R _C2 / R _C4 is smaller than 0.5, the correction capability for astigmatism and field curvature will be insufficient, and this will be a factor that deteriorates the flatness of the image surface in the entire zoom range. Become.

By satisfying the condition (7), "mainly monochromatic aberration" of the zoom lens can be corrected more favorably.

The three cemented lens has two "concave surfaces having a strong negative refracting power", and by arranging a positive refracting power to counter this, the aberration correction capability of the above-mentioned two concave surfaces is sufficient. Can be pulled out.

According to a seventh aspect of the present invention, when the second lens unit has at least one positive lens on the object side and the image side of the triplet cemented lens, respectively.
The second lens group as a whole has a "positive / negative / positive / negative / positive" configuration, which is very well-balanced in the arrangement of the refractive power. By adopting such a configuration, it is possible to prevent an excessive aberration from occurring on one lens surface, and to suppress deterioration of the imaging performance due to a manufacturing error such as decentering.

Therefore, with the structure of claim 7, the zoom lens can be made sufficiently small in size and have a wide angle of view, and high performance can be realized.

Furthermore, in order to reduce the size of the second lens unit (in particular, shorten the total length), it is effective to use an aspherical surface for the second lens unit. At this time, the aspherical surface is preferably provided on either or both of the positive lens arranged on the object side and the image side of the triplet cemented lens. The positive lens on the object side is close to the diaphragm and is effective mainly in correcting spherical aberration and coma. Since the positive lens on the image side is away from the diaphragm and the off-axis light flux passes through to some extent, it is effective in correcting astigmatism in addition to spherical aberration and coma.

Therefore, with the structure according to the eighth aspect, it is possible to correct the monochromatic aberration more favorably and realize a very high-performance zoom lens.

The first group of zoom lenses according to the present invention comprises, in order from the object side, a negative meniscus lens having a convex surface facing the object side, a negative lens having a large curvature surface facing the image side, and a large curvature surface facing the object side. It can be composed of three positive lenses. Since such a configuration has a high ability to correct off-axis aberrations, it is advantageous for widening the angle of view. For better aberration correction, it is desirable that the image-side surface of the negative lens (the surface having a large curvature on the image side) is an aspherical surface.

Further, the zoom lens of the present invention can "constitute the third lens group with one positive lens". The simple structure of the third lens unit is not only advantageous for downsizing the lens system, but also simplifies the mechanism when focusing is performed by the third lens unit.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the zoom lens of the present invention will be given below.

As shown in the aberration diagrams, in each of the examples, the aberration is sufficiently corrected, and it is possible to sufficiently cope with the light receiving element having 3 million to 5 million pixels. That is, by constructing the zoom lens as in the present invention, it is possible to sufficiently reduce the size and
It is clear that a very good image performance can be ensured while achieving a wide angle of view.

The meaning of each symbol in the examples is as follows. f: Focal length of the whole system F: F number ω: Half angle of view R: Radius of curvature D: Surface spacing (including diaphragm surface) Nd: Refractive index νd: Abbe number K: Aspherical conical constant A ₄ : Fourth order Aspherical coefficient A ₆ : 6th-order aspherical coefficient A ₈ : 8th-order aspherical coefficient A ₁₀ : 10th-order aspherical coefficient A ₁₂ : 12th-order aspherical coefficient A ₁₄ : 14th-order aspherical coefficient A ₁₆ : 16th-order aspherical coefficient A ₁₈ : 18th-order aspherical coefficient An aspherical surface is defined by the well-known formula below, where C is the reciprocal of the paraxial curvature radius (paraxial curvature) and H is the height from the optical axis. It is defined, and the conic constant: K, the higher-order aspherical surface coefficient: A _{4 to} A ₁₈
Specify the value of to specify the shape.

X = CH ² / [1 + √ (1- (1 + K) C ² H ² )] + A ₄ · H ⁴ + A ₆ · H
⁶ + A ₈ / H ⁸ + A ₁₀ / H ¹⁰ + A ₁₂ / H ¹² + A ₁₄ / H ¹⁴ + A ₁₆ / H ¹⁶ + A ₁₈ / H ¹⁸

[0043]

Examples Example 1 f = 5.97 to 16.87, F = 2.62 to 4.35, ω = 39.20 to 15.56 Surface number RD Nd νd Remark 01 62.725 1.20 1.77250 49.62 1st lens 02 10.255 1.50 03 19.975 1.20 1.74330 49.33 2nd lens 04 * 7.758 2.91 05 15.536 2.56 1.71736 29.50 Third lens 06 ∞ Variable (A) 07 Aperture 1.00 08 * 8.589 1.70 1.83400 37.34 Fourth lens 09 20.340 0.58 10 8.355 0.80 1.76182 26.61 5th lens 11 5.061 3.17 1.48749 70.44 6th lens 12- 15.985 0.80 1.64769 33.84 7th lens 13 7.369 0.57 14 21.429 1.58 1.74330 49.22 8th lens 15 * -41.619 Variable (B) 16 * 17.601 1.93 1.58913 61.25 9th lens 17 181.269 Variable (C) 18 ∞ 1.98 1.51680 64.20 Various filters 19 ∞ The first to third lenses are the first group, and the fourth to eighth lenses are the second group.
The group 9th lens is a 3rd group. The surface marked with * is a spherical surface.

The aspheric: fourth surface _{K = 0.0, A 4 = -2.88027} × 10 -4, A 6 = -6.01009 × 10 -6, A 8 = 2.79485 × 10 -7, A 10 = -1.38570 × 10 - ⁸ , A ₁₂ = 2.75096 × 10 ^-10 , A ₁₄ = -1.20000 × 10 ^-12 , A ₁₆ = -4.50197 × 10 ^-14 , A ₁₈ = 4.89891 × 10 ^-16 Aspheric surface: Eighth surface K = 0.0, A ₄ = -5.29387 x 10 ^-5 , A ₆ = 8.11971 x 10 ^-7 , A ₈ = -8.73056 x 10 ^-8 , A ₁₀ = 2.65984 x 10 ^-9 Aspherical surface: 15th surface K = 0.0, A ₄ = 2.60656 _{^{× 10 -4, A 6 = 4.73782}} × 10 -6, A 8 = 3.71246 × 10 -7, A 10 = -6.41360 × 10 -10 aspherical: 16th surface _{K = 0.0, A 4 = -1.09895} × 10 - ⁵ , A ₆ = 2.57475 × 10 ^-6 , A ₈ = -9.80625 × 10 ^-8 , A ₁₀ = 1.86997 × 10 ^-9 Variable distance Short focal length Intermediate focal length Long focal length f = 5.97 f = 10.04 f = 10.18 A 21.260 8.610 1.500 B 3.680 8.640 17.630 C 4.427 4.268 3.098 Numerical value of the parameter of the conditional expression (R _C2 / R _C4 ) = 0.687 FIG. 1 is a diagram showing a lens configuration of the zoom lens of the first embodiment. In the figure, the symbol F indicates the above "various filters".

Example 2 f = 5.97 to 16.89, F = 2.62 to 4.56, ω = 39.18 to 15.54 Surface number RD Nd νd Remark 01 28.580 1.20 1.77250 49.62 First lens 02 8.268 2.09 03 29.590 1.20 1.80610 40.74 Second lens 04 * 9.261 3.24 05 17.404 2.11 1.76182 26.61 3rd lens 06 501.306 Variable (A) 07 Aperture 1.00 08 * 9.217 1.90 1.83400 37.34 4th lens 09 28.441 1.09 10 11.494 1.45 1.80518 25.46 5th lens 11 5.703 3.28 1.49700 81.61 6th lens 12 -10.031 0.80 1.62004 36.30 7th lens 13 9.379 0.44 14 24.724 1.85 1.70154 41.15 8th lens 15 * -26.923 Variable (B) 16 * 20.386 1.83 1.58913 61.25 9th lens 17 220.476 Variable (C) 18 ∞ 1.98 1.51680 64.20 Various filters 19 ∞ 9th The first to third lenses are the first group, and the fourth to eighth lenses are the second group.
The group 9th lens is a 3rd group. The surface marked with * is a spherical surface.

The aspheric: fourth surface _{K = 0.0, A 4 = -2.29550} × 10 -4, A 6 = -3.47013 × 10 -6, A 8 = 2.75845 × 10 -7, A 10 = -1.89585 × 10 - ⁸ , A ₁₂ = 5.22397 × 10 ^-10 , A ₁₄ = -2.28012 × 10 ^-12 , A ₁₆ = -1.63935 × 10 ^-13 , A ₁₈ = 2.28889 × 10 ^-15 Aspherical surface: 8th surface K = 0.0, A ₄ = -6.58062 × 10 ^-5 , A ₆ = 1.14936 × 10 ^-6 , A ₈ = -1.26545 × 10 ^-7 , A ₁₀ = 3.79974 × 10 ^-9 Aspheric surface: 15th surface K = 0.0, A ₄ = 2.08131 _{^{× 10 -4, A 6 = 4.65854}} × 10 -6, A 8 = 2.28057 × 10 -7, A 10 = -2.79019 × 10 -9 aspherical: 16th surface _{K = 0.0, A 4 = -4.28029} × 10 - ⁶ , A ₆ = 2.20357 × 10 ^-6 , A ₈ = -7.52231 × 10 ^-8 , A ₁₀ = 1.35906 × 10 ^-9 Variable interval Short focal length Intermediate focal length Long focal length f = 5.97 f = 10.05 f = 16.89 A 19.290 7.420 1.510 B 3.130 7.820 19.070 C 5.144 5.618 3.110 Numerical value of the parameter of the conditional expression (R _C2 / R _C4 ) = 0.608 FIG. 2 shows the lens configuration of the zoom lens of Example 2 in accordance with FIG. 1.

Example 3 f = 5.93 to 16.86, F = 2.80 to 4.67, ω = 39.18 to 15.54 Surface number RD Nd νd Remark 01 27.153 1.50 1.77250 49.62 First lens 02 8.488 2.33 03 29.611 1.20 1.74330 49.33 Second lens 04 * 8.616 2.74 05 15.215 2.37 1.71736 29.50 3rd lens 06 274.175 Variable (A) 07 Aperture 1.00 08 * 9.107 1.77 1.80420 46.50 4th lens 09 57.756 1.40 10 10.880 0.88 1.82027 29.70 5th lens 11 5.494 2.41 1.48749 70.44 6th lens 12 16.048 0.80 1.84666 23.78 7th lens 13 7.345 0.59 14 29.391 1.60 1.77250 49.62 8th lens 15 -27.788 Variable (B) 16 * 17.406 1.88 1.58913 61.25 9th lens 17 111.481 Variable (C) 18 ∞ 1.98 1.51680 64.20 Various filters 19 ∞ 1st to 1st The third lens is the first group, and the fourth to eighth lenses are the second group.
The group 9th lens is a 3rd group. The surface marked with * is a spherical surface.

The aspheric: fourth surface _{K = 0.0, A 4 = -2.32229} × 10 -4, A 6 = -6.31837 × 10 -6, A 8 = 4.27101 × 10 -7, A 10 = -2.21703 × 10 - ⁸ , A ₁₂ = 4.75981 × 10 ^-10 , A ₁₄ = -6.35199 × 10 ^-13 , A ₁₆ = -1.36560 × 10 ^-13 , A ₁₈ = 1.51878 × 10 ^-15 Aspherical surface: 8th surface K = 0.0, A ₄ = -1.16901 × 10 ^-4 , A ₆ = -3.08214 × 10 ^-8 , A ₈ = -6.84811 × 10 ^-8 , A ₁₀ = 1.84472 × 10 ^-9 Aspheric surface: 16th surface K = 0.0, A ₄ = -4.24072 × 10 ^-5 , A ₆ = 5.73436 × 10 ^-6 , A ₈ = -2.30527 × 10 ^-7 , A ₁₀ = 3.88547 × 10 ^-9 Variable distance Short focal length Intermediate focal length Long focal length f = 5.93 f = 10.04 f = 16.86 A 20.290 8.280 1.520 B 4.070 9.240 18.250 C 4.205 4.046 3.131 Numerical value of the parameter of the conditional expression (R _C2 / R _C4 ) = 0.748 FIGS. 4 to 6 show aberration curves of the zoom lens of the first embodiment. 4 is at the short focal end, FIG. 5 is at the intermediate focal length, and FIG. 6 is at the long focal end. 7 to 9 show aberration curves of the zoom lens of the second embodiment. 7 is at the short focal end, FIG. 8 is at the intermediate focal length, and FIG. 9 is at the long focal end. Figure 1
0 to 12 show aberration curves of the zoom lens of the third embodiment. FIG. 10 shows the short focal point, FIG. 11 shows the intermediate focal length,
Is at the long focus end. In each aberration diagram, the broken line in the diagram of spherical aberration represents the “sine condition”. In the diagram of astigmatism, the solid line represents sagittal and the broken line represents meridional.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIG. 13 and FIG.
An embodiment of a camera device as a portable information terminal device will be described. 13A and 13B are views showing the front side and the upper surface, and FIG. 13C is a view showing the back side. Camera device 3
Reference numeral 0 denotes the photographing lens 31 described above.
The zoom lens according to any one of 8 (more specifically,
For example, the appropriate ones of the above-described first to third embodiments) are included as a “shooting zoom lens”.

In FIG. 13A, reference numeral 32 is a flash and reference numeral 33 is a finder. Zoom lever 34
The shutter button 35 and the shutter button 35 are arranged on the upper surface side of the main body. FIG. 13B is a diagram showing a usage state of the taking lens 31. The photographic lens 31 is shown in FIG.
As shown in FIG. 3A, the camera body is stored in a “collapsed type”. In each of the above embodiments of the zoom lens, the number of lenses is as small as nine, and the thickness of the second lens group is also small, so that the lens can be stored in a thin camera body by retracting the lens.

As shown in FIG. 13C, the power switch 36, the operation button 37, and the liquid crystal monitor 38 are arranged on the rear side of the camera body, and the communication card slot 39A is provided.
The memory card slot 39B is arranged on the side surface of the main body.

FIG. 14 shows the "system structure" of the camera device.
FIG. The camera device 30 is a personal digital assistant device. As shown in FIG. 14, the camera device has a photographing lens 31 and a light receiving element (area sensor) 45, and an image of an object to be photographed formed by the photographing lens 31 is received by the light receiving element 4.
The signal processing device 4 is configured to be read by 5 and the output from the light receiving element 45 is controlled by the central processing unit 40.
2 is processed and converted into digital information. That is, the camera device 30 has a “function of using a captured image as digital information”.

The image information digitized by the signal processing device 42 is subjected to predetermined image processing in the image processing device 41 under the control of the central processing unit 40, and then is set in the semiconductor memory 44 (set in the memory card slot 39B). Recorded). On the liquid crystal monitor 38, it is possible to display the image that is being photographed or the image recorded in the semiconductor memory 44. Further, the image recorded in the semiconductor memory 44 can be transmitted to the outside by using the communication card 43 or the like (set in the communication card slot 39A).

As shown in FIG. 13A, the taking lens 3
1 is in the “collapsed state” when the camera device 30 is carried, and when the user operates the power switch 36 to turn on the power, the lens barrel is extended as shown in FIG. 13B. At this time, each group of zoom lenses in the lens barrel is, for example, “arrangement at the short focal end”, and the arrangement of each group is changed by operating the zoom lever 34 to change the magnification to the long focal end. It can be performed. At this time, the viewfinder 33 also changes its magnification in association with the change in the angle of view of the taking lens.

Focusing is performed by "half-pressing" the shutter button 35. Focusing can be performed by moving the first group, the third group, or the light receiving element. When the shutter button 35 is further pressed from the half-pressed state, shooting is performed, and thereafter, the above image information processing is executed.

When the image recorded in the semiconductor memory 44 is displayed on the liquid crystal monitor 38 or transmitted to the outside using the communication card 43 or the like, the operation button 37 is operated. If any one of the first to third embodiments is used as the taking lens 31, these have good performance. Therefore, a high-quality and compact camera using a light receiving element 45 of 3 to 5 million pixel class is used. The device can be realized.

[0057]

As described above, according to the present invention, a novel zoom lens and camera device can be realized. As described above, the zoom lens of the present invention is sufficiently compact and
A wide angle of view can be realized, and high performance is achieved.
It is possible to realize a resolving power corresponding to an image sensor of 5 million pixels. Therefore, by using this zoom lens as a photographing optical system of a camera function unit, a compact and high-quality camera device (a portable information terminal device or the like) can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a zoom lens of Example 1.

FIG. 2 is a sectional view illustrating a configuration of a zoom lens of Example 2.

FIG. 3 is a cross-sectional view showing a configuration of a zoom lens of Example 3.

FIG. 4 is an aberration curve diagram at a short focal length end of the zoom lens of Embodiment 1.

FIG. 5 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 1.

FIG. 6 is an aberration curve diagram at the long focal length end of the zoom lens of Embodiment 1.

FIG. 7 is an aberration curve diagram at a short focus end of the zoom lens in Example 2;

8 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 2. FIG.

FIG. 9 is an aberration curve diagram at a long focal length end of the zoom lens in Example 2;

FIG. 10 is an aberration curve diagram for a zoom lens according to Example 3 at the short focus end.

FIG. 11 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 3.

FIG. 12 is a diagram of aberration curves at the long focal length end of the zoom lens in Example 3;

FIG. 13 is a first embodiment of a camera device (personal digital assistant device).
It is an external view which shows a form.

14 is a diagram showing a system structure of the camera device of FIG.

[Explanation of symbols]

I Group 1 II Second group III Group 3 S aperture F Various filters

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 5/00 G03B 5/00 E

Claims (9)

[Claims] 1. A first lens having a negative focal length in order from the object side.
Group, a second group having a positive focal length, and a third group having a positive focal length are arranged, and an aperture stop that moves integrally with the second group is provided on the object side of the second group to provide a short focal point. At the time of zooming from the end to the long focal length end, in the zoom lens in which the second group moves monotonically from the image side to the object side, and the first group moves so as to correct the change in image plane position due to zooming, The zoom lens, wherein the second group includes a three-piece cemented lens including a negative lens, a positive lens, and a negative lens in order from the object side. 2. The zoom lens according to claim 1, wherein the negative lens arranged closest to the object side of the third cemented lens of the second group has a meniscus shape with a concave surface facing the image side. Zoom lens. 3. The zoom lens according to claim 1, wherein the negative lens arranged closest to the image side of the third cemented lens in the second group has a strong concave surface facing the image side. Zoom lens. 4. The zoom lens according to claim 1, 2 or 3, wherein the positive lens disposed in the middle of the three-lens cemented lens of the second group has a refractive index: N _C2 and an Abbe number: ν _C2 , and conditions: (1) A zoom lens characterized by satisfying 1.45 <N _C2 <1.52 (2) 68 <ν _C2 <85. 5. The zoom lens according to claim 4, wherein the negative lens arranged closest to the object side of the third cemented lens in the second group has a refractive index of N _C1 , an Abbe number of ν _C1 , and a third lens group of 3
The refractive index of the negative lens arranged closest to the image side of the cemented doublet lens is N _C3 and the Abbe number is ν _C3 : (3) 1.75 <N _C1 <1.95 (4) 20 <ν _C1 <35 (5) 1.60 <N _C3 <1.95 (6) A zoom lens characterized by satisfying 20 <ν _C3 <40. 6. The zoom lens according to any one of claims 1 to 5, wherein a radius of curvature of the cemented surface on the object side of the cemented lens on the object side of the second lens group of 3 lenses: R _C2 Radius of curvature: R _C4
Conditions: (7) A zoom lens characterized by satisfying 0.5 <( _RC2 / _RC4 ) <0.85. 7. The zoom lens according to any one of claims 1 to 6, wherein the second group has at least one positive lens on the object side and the image side of the triplet cemented lens, respectively. And a zoom lens. 8. The zoom lens according to claim 7, wherein at least one of the positive lenses arranged on the object side and the image side of the triplet cemented lens has an aspherical surface. 9. A camera device comprising the zoom lens according to claim 1 as a photographing optical system of a camera function section.