JP2007003873A - Zoom lens and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens made compact, securing high image quality performance and advantageously obtaining higher image quality while keeping an appropriate variable power ratio, and an imaging apparatus in which the zoom lens is mounted. <P>SOLUTION: The three-group zoom lens has a first group G1 having a negative refractive power, a second group G2 having a positive refractive power and a third group G3 having a positive refractive power in order from an object side, and performs variable power by changing a space between the respective groups. The first group G1 is constituted of one negative lens L11, the second group G2 is constituted of one positive lens L21 and one negative lens L22 in order from the object side, and the third group G3 is constituted of one positive lens L31, and the space between the first group G1 and the second group G2 satisfies a condition of 1.2 mm≤D12t≤3.0 mm, where D12t is the space between the first group and the second group at a telephoto end. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a zoom lens and an image pickup apparatus using the same, and particularly includes a compact zoom lens and the like (for example, incorporated in a digital camera, a video camera, a digital video unit, a personal computer, a mobile computer, a mobile phone, an information portable terminal, etc. The present invention relates to an electronic imaging device (or externally attached).

In recent years, portable information terminals and mobile phones called PDAs have exploded, and built-in compact digital cameras and digital video units using CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) sensors as image sensors. Things are increasing. Recently, an image sensor having a relatively small size and a high pixel number (megapixel) has been developed, and a small and high-performance optical system has been required. Conventionally, as one of small optical systems, there is a negative / positive three-group zoom lens (see, for example, Patent Document 1). Such an optical system can be used in a mobile phone, a small information terminal, and the like. Preferably used.
JP 2003-177315 A

  By the way, in a small imaging camera represented by a mobile phone at present, a method of controlling exposure with an electronic shutter is the mainstream. When the image pickup device is a CCD and an electronic shutter, there is a drawback that a phenomenon called “smear” is likely to occur when a strong light enters a line in the vertical direction. Further, when the image sensor is a CMOS sensor, there is a problem that image distortion due to movement is likely to occur and it is difficult to improve image quality.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a zoom lens that is small and advantageous in improving image quality while maintaining an appropriate zoom ratio, and an image pickup apparatus equipped with the zoom lens. Is to provide.

In order to achieve the above object, a zoom lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power. A three-group zoom lens that performs zooming by changing between the groups, wherein the first group with negative refractive power is composed of one negative lens, and the second group with positive refractive power is on the object side In order from one positive lens and one negative lens, the third group of positive refractive power is composed of one positive lens, and the group interval between the first group and the second group is as follows: It is characterized by satisfying.
1.2mm ≤ D12t ≤ 3.0mm
D12t is the distance between the first group and the second group at the telephoto end.

The zoom lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. It is a three-group zoom lens that performs zooming by changing between the groups. The first group having the negative refractive power is composed of one negative lens, and the positive second group is the positive lens 1 in order from the object side. And the third lens group having a positive refractive power is composed of one positive lens, and the distance between the aperture stop and the second lens group satisfies the following condition. To do.
0.3mm ≤ Ds2t ≤ 1.2mm
Here, Ds2t is the distance between the aperture stop and the second group at the telephoto end.

  The zoom lens according to the present invention is preferably characterized in that a shutter mechanism is disposed in the vicinity of the aperture stop.

  According to the present invention, it is preferable that the shutter mechanism is a mechanical shutter.

The zoom lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. The zoom lens is a three-group zoom lens that performs zooming by changing between the groups. The first lens unit having the negative refractive power is composed of one negative lens, and the second lens unit having the positive refractive power is sequentially arranged from the object side. It is composed of one positive lens and one negative lens, the third group of positive refractive power is composed of one positive lens, and the distance between the aperture stop and the second group satisfies the following conditions. It is characterized by.
1.2mm ≤ D12t ≤ 3.0mm
0.3mm ≤ Ds2t ≤ 1.2mm
Here, D12t is the distance between the first group and the second group at the telephoto end, and Ds2t is the distance between the stop and the second group at the telephoto end.

In the zoom lens according to the present invention, it is preferable that the air lens in the second group satisfies the following conditions.
-5.0 <(r5 + r6) / (r5-r6) <2.0
Here, r5 is the radius of curvature of the image side surface of the second lens group positive lens, and r6 is the radius of curvature of the object side surface of the second lens group negative lens.

In the zoom lens according to the present invention, it is preferable that the negative lens constituting the second group satisfies the following conditions.
0.1 <r7 / fw ≤ 1.1
Here, r7 is the radius of curvature of the surface closest to the image side of the negative lens constituting the second group, and fw is the focal length of the entire system at the wide angle end.

In the zoom lens according to the present invention, it is preferable that the Abbe number νd1 of the negative lens in the first group satisfies the following condition.
50 <νd1

In the zoom lens according to the present invention, it is preferable that the Abbe number νd2 of the positive lens constituting the second group satisfies the following condition.
50 <νd2

In the zoom lens according to the present invention, it is preferable that the refractive index N2P of the positive lens constituting the second group satisfies the following condition.
1.5 <N2P

  In the zoom lens according to the present invention, preferably, the positive lens forming the third group is coated with an infrared cut function.

  In the zoom lens according to the present invention, it is preferable that the third group is composed of one glass lens.

  In the zoom lens according to the present invention, it is preferable that the first group and the second group each include at least one glass lens.

  The zoom lens according to the present invention is preferably characterized in that at least one plastic lens is used.

In the zoom lens according to the present invention, it is preferable that the positive lens in the third group satisfies the following conditional expression.
0.3 <(r8 + r9) / (r8-r9) <3.0
Here, r8 and r9 are the radii of curvature of the object-side surface and the image-side surface of the third group positive lens, respectively.

In the zoom lens according to the present invention, it is preferable that the second group satisfies the following conditional expression.
0.8 <f2 / fw <1.6
Here, f2 is the focal length of the second group, and fw is the focal length of the entire system at the wide angle end.

In the zoom lens according to the present invention, it is preferable that the third group satisfies the following conditional expression.
1.3 <f3 / fw <4.0
Here, f3 is the focal length of the third lens unit, and fw is the focal length of the entire system at the wide angle end.

  The zoom lens according to the present invention is preferably characterized in that focusing is performed by moving the first group.

  The zoom lens according to the present invention is preferably characterized in that focusing is performed by moving the third group.

An image pickup apparatus according to the present invention includes the three-group zoom lens and an image pickup element disposed on the image side thereof, and the total thickness G2L of the lenses constituting the second group satisfies the following conditional expression (8): It is characterized by satisfaction.
0.6 <(G2L) / Y '<1.16
However, Y ′ is half the diagonal length of the effective imaging area of the imaging device.

  According to the present invention, it is possible to provide a zoom lens and an imaging apparatus that are advantageous for high image quality while maintaining a suitable zoom ratio and being small in size and ensuring high image quality performance.

Hereinafter, examples of the present invention will be described, but prior to that, operational effects of the present invention will be described.
The zoom lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power, and changes between the groups. The first group with negative refractive power is composed of one negative lens, and the second group with positive refractive power is composed of one positive lens in order from the object side. The third group having positive refractive power is composed of one positive lens, and the group interval between the first group and the second group satisfies the following condition. Yes.
1.2mm ≤ D12t ≤ 3.0mm (1)
D12t is the distance between the first group and the second group at the telephoto end.
The negative and positive wide-angle zoom lens with the above configuration ensures optical performance that can cope with high image quality. However, by using this zoom lens in combination with a mechanical shutter mechanism, the above-mentioned problems can be solved, and an extra Since light is not guided onto the image sensor, a clearer and higher quality image can be provided.
By satisfying the above condition (1), it is possible to secure a space for the mechanical shutter member, and to secure a margin space accompanying movement such as movement of the lens group by zooming and movement of the lens group by focusing.
If the upper limit of condition (1) is exceeded, the size from the first surface to the image surface at the wide angle increases, the ball diameter of the first negative lens also increases, and the optical system becomes large. Further, the off-axis aberration generated in the first negative lens is large, and the field curvature aberration cannot be sufficiently corrected. Alternatively, the imaging area of the imaging element is increased, the entire optical system is increased, and this is disadvantageous in terms of energy consumption and the layout of the entire apparatus. On the other hand, below the lower limit, the retrofocus effect is reduced and it is difficult to ensure the back focus.

The zoom lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. It is a three-group zoom lens that performs zooming by changing between the groups. The first group having the negative refractive power is composed of one negative lens, and the positive second group is the positive lens 1 in order from the object side. And the third lens group having a positive refractive power is composed of one positive lens, and the distance between the aperture stop and the second lens group satisfies the following condition. Yes.
0.3mm ≤ Ds2t ≤ 1.2mm (2)
Here, Ds2t is the distance between the aperture stop and the second group at the telephoto end.
The positive and negative wide-angle zoom lens with the above-mentioned configuration ensures optical performance that can cope with high image quality, but this zoom lens is equipped with a mechanism that can switch between the light-blocking state and the light-transmitting state, such as a mechanical shutter mechanism. Thus, the above-described problems can be solved and extra light is not guided onto the image sensor, so that a clearer and higher quality image can be provided.
If the upper limit of the condition (2) is exceeded, the ball diameters of the second group and the third group are increased particularly when trying to cope with the wide angle, and the size increases. Further, the off-axis aberration generated in the second group increases, and the field curvature aberration cannot be corrected. Alternatively, the imaging area of the imaging device is increased, and the entire zoom lens becomes larger, which is disadvantageous in terms of energy consumption and the layout of the entire apparatus. If the lower limit is not reached, a space for inserting a mechanical shutter member or the like cannot be taken, and the above-described problems occur. Alternatively, increasing the cost or increasing the size of the mechanical shutter mechanism or the like is disadvantageous in terms of the layout of the entire apparatus.

The zoom lens according to the present invention is preferably characterized in that a shutter mechanism, preferably a mechanical shutter, is disposed in the vicinity of the aperture stop.
The mechanical shutter can be composed of a thin plate or film as a light shielding member, and the shutter can be arranged without increasing the distance between the first group and the second group so much. Thus, the mechanical shutter can achieve downsizing and high image quality.

In the zoom lens according to the present invention, it is preferable that the air lens in the second group satisfies the following conditions.
-5.0 <(r5 + r6) / (r5-r6) <2.0 (3)
Here, r5 is the radius of curvature of the image side surface of the second lens group positive lens, and r6 is the radius of curvature of the object side surface of the second lens group negative lens.
By satisfying the above condition (3), the second group can be made to have a relatively strong power, and high zooming can be realized even with the same group interval. If the upper limit of condition (3) is exceeded, the amount of aberration generated on the object side surface of the negative lens in the second lens group becomes large, and it becomes difficult to correct field curvature aberration. Below the lower limit, correction of field curvature aberration and coma becomes difficult, which is not preferable.
Furthermore, it is more preferable to satisfy the following conditions, since the amount of various off-axis aberrations, particularly field curvature aberrations, can be further reduced.
-3.8 <(r5 + r6) / (r5-r6) <0 (3-1)
When the following conditions are satisfied, the amount of off-axis aberrations, particularly the curvature of field, can be further reduced, which is more preferable.

In the zoom lens according to the present invention, it is preferable that the negative lens constituting the second group satisfies the following conditions.
0.1 <r7 / fw ≤ 1.1 (4)
Here, r7 is the radius of curvature of the surface closest to the image side of the negative lens constituting the second group, and fw is the focal length of the entire system at the wide angle end.
If the lower limit of conditional expression (4) is not reached, the amount of coma aberration generated on the surface closest to the image side of the negative lens constituting the second group will increase, causing a deterioration in the performance of the peripheral portion. When the value exceeds the upper limit, the negative component aberration on the surface becomes too small, and the positive component spherical aberration generated in other lens elements cannot be corrected, which is not preferable.
Furthermore, it is more preferable to satisfy the following conditions, since the amount of various aberrations can be further reduced.
0.23 <r7 / fw ≦ 1.0 (4-1)

The zoom lens according to the present invention is preferably characterized in that the Abbe number νd1 of the negative lens in the first group satisfies the following condition.
50 <νd1 (5)
By satisfying the conditional expression (5), it is possible to improve chromatic aberration. If the lower limit of conditional expression (5) is not reached, chromatic aberration occurring in the first group cannot be corrected, and it becomes difficult to ensure performance. In addition, when the first lens group is made of a glass material, it is preferable to select a low-dispersion anomalous dispersion glass material, which makes it possible to suppress the variation in axial chromatic aberration due to zooming.
Furthermore, it is more preferable to satisfy the following conditions.
50 <νd1 <100 (5-1)
If the upper limit of conditional expression (5-1) is exceeded, it will be difficult to find an optical material.

In the zoom lens according to the present invention, it is preferable that the Abbe number νd2 of the positive lens constituting the second group satisfies the following condition.
50 <νd2 (6)
By satisfying the conditional expression (6), it is possible to improve chromatic aberration. If the upper limit of conditional expression (6) is exceeded, no optical material is present. Below the lower limit, the longitudinal chromatic aberration that is particularly large during telephoto cannot be corrected, and it becomes difficult to ensure performance. In addition, when the positive lens constituting the two groups is made of a glass material, it is preferable to select a glass material with low dispersion and anomalous dispersion, and this makes it possible to suppress fluctuations in axial chromatic aberration due to zooming.
Furthermore, it is more preferable that the following conditions are satisfied.
50 <νd2 <100 (6-1)
If the upper limit of conditional expression (6-1) is exceeded, it will be difficult to find an optical material.

The zoom lens according to the present invention is preferably characterized in that the refractive index N2P of the positive lens constituting the second group satisfies the following condition.
1.5 <N2P (7)
By selecting a glass material having a high refractive index exceeding 1.5 for the positive lens constituting the second group that satisfies the above conditional expression (7), the Petzval sum generated in the lens can be kept small. The upper limit is determined by the production limit of the glass material. In addition, by selecting a glass material having an appropriate Abbe number for the lens, it is possible to reduce the axial chromatic aberration, which becomes large especially at telephoto.

In the zoom lens according to the present invention, preferably, the positive lens constituting the third group is coated with an infrared cut function.
This eliminates the need for an infrared cut filter and enables further miniaturization. In particular, in an optical system in which the exit pupil is separated to some extent due to the characteristics of an electronic imaging device such as a CCD, a stable infrared cut effect can be easily obtained by coating a lens close to the image plane with an infrared cut function. Moreover, it is desirable that the lens for coating having an infrared cut function is a glass material. That is, since the glass material is hardly deformed by heat and hardly absorbs moisture, it is easy to increase the number of coating layers, which is advantageous for coating with an infrared cut function.

In the zoom lens according to the present invention, it is preferable that the third group is composed of one glass lens.
By configuring at least one lens in the third group with a glass lens, off-axis aberrations, particularly field curvature aberrations, can be corrected more satisfactorily. That is, the refractive index and Abbe number can be freely selected. In addition, the lens surface can be made more accurate and thinner than plastic lenses, so the effect of selecting a high refractive index can be combined to make the lens thin while ensuring the necessary lens power. Can contribute to the development.

The zoom lens according to the present invention is preferably characterized in that each of the first group and the second group is composed of at least one glass lens.
The optical plastic material has a refractive index of about 1.5, but by selecting a glass material with a higher refractive index for the second group positive lens, the Petzval sum generated by the lens can be kept small. Is possible. Further, by using the two lenses as a glass material, it is possible to suppress the amount of aberration fluctuation at the time of zooming, and in particular to keep axial chromatic aberration better. In addition, by using a glass lens with negative and positive refractive powers, it is possible to further reduce image plane displacement due to temperature changes.

The zoom lens according to the present invention is preferably characterized in that at least one plastic lens is used.
By using a plastic lens, it is possible to reduce the cost and weight of the zoom lens.

In the zoom lens according to the present invention, it is preferable that the positive lens in the third group satisfies the following conditions.
0.3 <(r8 + r9) / (r8-r9) <3.0 (8)
Here, r8 and r9 are the radii of curvature of the object-side surface and the image-side surface of the third group positive lens, respectively.
Conditional expression (8) is a condition for providing an optical system with a short overall length without increasing the exit angle of the off-axis light beam. When the upper limit is exceeded, the exit angle of the off-axis light beam becomes too large. This contributes to a lack of light in the peripheral area. In addition, the deterioration of off-axis aberrations, particularly coma, cannot be corrected satisfactorily. Below the lower limit, the total length of the optical system tends to be long, which is disadvantageous for miniaturization.

In the zoom lens according to the present invention, it is preferable that the second group satisfies the following conditions.
0.8 <f2 / fw <1.6 (9)
Here, f2 is the focal length of the second group, and fw is the focal length of the entire system at the wide angle end.
If the upper limit of conditional expression (9) is exceeded, the refractive power of the second group becomes weak, and if an appropriate zoom ratio is to be secured, the optical system becomes large. If the value is below the lower limit, it is advantageous for downsizing, but the amount of aberration generated in the second group increases, which is not preferable for off-axis aberration correction.

In the zoom lens according to the present invention, it is preferable that the third group satisfies the following conditions.
1.3 <f3 / fw <4.0 (10)
Here, f3 is the focal length of the third lens unit, and fw is the focal length of the entire system at the wide angle end.
Exceeding the upper limit of the conditional expression (10) is advantageous for securing the back focus and correcting the aberration, but the total length of the zoom lens becomes long, which is disadvantageous for miniaturization. If the value is below the lower limit, off-axis aberrations are deteriorated, and especially coma aberration cannot be corrected.

The zoom lens according to the present invention is preferably characterized in that focusing is performed by moving the first group.
It is preferable to perform focusing by moving the negative lens, which is the first group, because aberration fluctuations with respect to distance changes are small.
The zoom lens according to the present invention is preferably characterized in that focusing is performed by moving the third group.
When focusing is performed by moving the positive lens which is the third group, the driving advantage can be maintained. That is, since the third group focusing motor can be arranged in the rear part, a lens frame structure for retracting the first group is also possible.
In the present invention, a configuration in which the movable group is reduced by fixing the third group and the lens frame mechanism is simplified is possible, and the third group is made movable so that off-axis aberrations, particularly field curvature. Although it is possible to make the aberration correction advantageous and to improve the peripheral image quality, it is desirable to appropriately select these according to the characteristics required of the imaging apparatus.

The image pickup apparatus according to the present invention includes the third group zoom lens and an image pickup element disposed on the image side thereof, and the total thickness G2L of the lenses constituting the second group satisfies the following condition. It is a feature.
0.6 <(G2L) / Y '<1.16 (11)
However, Y ′ is half the diagonal length of the effective imaging area of the imaging device.
If the upper limit of conditional expression (11) is exceeded, the total length of the second group becomes large, which contributes to an increase in the overall size of the optical system. Below the lower limit, it is advantageous for miniaturization, but it is not desirable in terms of processing and assembly because the lens becomes thinner and more easily damaged with respect to its diameter.

Next, a zoom lens according to the present invention and an electronic image pickup apparatus using the same will be described based on the illustrated embodiments.
Example 1
1A and 1B are cross-sectional views along the optical axis showing the configuration of the first embodiment of the zoom lens according to the present invention, wherein FIG. 1A shows the wide-angle end, FIG. 1B shows the middle, and FIG. 1C shows the telephoto end. ing.. 2A, 2B, and 2C show the spherical aberration, astigmatism, and distortion of the zoom lens in FIG. 1 in the states of FIGS. 2A, 2B, and 2C, respectively. . Note that it is assumed that distortion is corrected by image processing after light reception by an electronic image sensor.

The zoom lens of the first embodiment includes, in order from the object side, a first group G1 having a negative refractive power, an aperture stop S, a second group G2 having a positive refractive power, and a third group having a positive refractive power. And G3. CG is a cover glass, and I is an image pickup surface of an electronic image pickup device such as a CCD.
The first group G1 includes a biconcave negative lens L11 having both aspheric surfaces, and the second group G2 has an aspheric surface on the image side with an air gap from the biconvex positive lens L21 having both surfaces aspheric. The third group G3 is composed of a biconvex positive lens L31 whose surface on the image side is an aspherical surface, and the first lens unit L3 is used for zooming from the wide-angle end to the telephoto end. A zoom method is employed in which the distance between the first group G1 and the second group decreases, and the distance between the second group G2 and the third group G3 increases.
The first group G1 moves along a locus convex toward the image side, the second group G2 always moves toward the object side together with the aperture stop S, and the third group G3 is fixed.

Next, numerical data of optical members constituting the zoom lens of the first embodiment are shown. In this data, R represents the radius of curvature of each lens surface, D represents the thickness or air spacing of each lens, Nd represents the refractive index of each lens at the d-line, and Vd represents the Abbe number of each lens.
The aspheric coefficient is expressed as follows when the optical axis direction is z, the direction orthogonal to the optical axis direction is y, R is the radius of curvature of each lens surface, k is the cone coefficient, and A4, A6, A8, and A10. It is expressed by the following formula.
^{z = (y 2 / R)} / [1+ [1- (1 + k) (y / R) 2] 1/2] + A4y 4
+ A6y ⁶ + A8y ⁸ + A10y ¹⁰
Of the aspheric coefficients, for example, A4 -4.4963E-03 of the aspherical surface (surface number 1) in the numerical data 1 can also be expressed as A4 = -4.4963 × 10 ^-3. It is displayed in the format.

Numerical data 1
Focal length (f) 3.2mm to 8.5mm
F number (FNO) 2.8-4.8
Angle of view (2ω) 76.2 ° ~ 28.8 °
Effective imaging area (diagonal length) 4.5mm

Surface number RD Nd Vd
1 * -7.898 0.67 1.52542 55.78 (Plastic lens)
2 * 6.245 D1
3 (Aperture) ∞ 0.75
4 * 2.581 1.40 1.52542 55.78 (plastic lens)
5 * -3.679 1.02
6 -8.795 0.99 1.60687 27.03 (plastic lens)
7 * 3.222 D2
8 19.576 0.88 1.52542 55.78 (Plastic lens)
9 * -7.913 1.40
10 ∞ 0.50 1.51633 64.14
11 ∞ 0.50
12 (imaging surface) ∞
* Aspherical

Aspheric coefficient

Surface number R k
1 -7.898 0.
A4 A6 A8
-4.4963E-03 1.1928E-03 -6.1456E-05

Surface number R k
2 6.2448 0.
A4 A6 A8
-5.9954E-03 1.8182E-03 5.4713E-06

Surface number R k
4 2.5813 -1.9920
A4 A6
6.8196E-03 -4.6381E-04

Surface number R k
5 -3.6790 0.
A4 A6 A8
1.1181E-02 -1.2020E-03 8.4288E-05

Surface number R k
7 3.2218 3.1471
A4 A6 A8
-1.3938E-02 4.6177E-03 -1.5879E-03

Surface number R k
9 -7.9130 -0.7915
A4 A6 A8
6.5630E-03 -1.1630E-03 7.0550E-05

Zoom data

f 3.2 5.1 8.5
FNO 2.8 3.5 4.8
ω 38.10 ° 24.70 ° 14.40 °
D1 5.83 3.30 1.53
D2 0.65 2.25 5.20

Example 2
FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the second embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. ing.. FIGS. 4A, 4B, and 4C show the spherical aberration, astigmatism, and distortion of the zoom lens shown in FIG. 3 in the states of FIGS. 4A and 4B, respectively. . Note that it is assumed that distortion is corrected by image processing after light reception by an electronic image sensor.

The zoom lens of the second embodiment includes, in order from the object side, a first group G1 having a negative refractive power, an aperture stop S, a second group G2 having a positive refractive power, and a third group having a positive refractive power. And G3. CG is a cover glass, and I is an image pickup surface of an electronic image pickup device such as a CCD.
The first group G1 is composed of a biconcave negative lens L11 having both aspheric surfaces, and the second group G2 is a biconcave having both surfaces aspheric with a biconvex positive lens L21 having both surfaces aspheric. The third lens unit G3 includes a negative lens L22, and the third lens unit G3 includes a meniscus lens L31 having a convex surface facing the image side, both surfaces of which are aspherical surfaces. A zoom method is employed in which the distance between the group G1 and the second group decreases and the distance between the second group G2 and the third group G3 increases.
The first group G1 moves along a locus convex toward the image side, the second group G2 always moves toward the object side together with the aperture stop S, and the third group G3 is fixed.

Numerical data 2
Focal length (f) 3.8mm ~ 10.6mm
F number (FNO) 2.8-5.4
Angle of view (2ω) 63.6 ° ~ 24.3 °
Effective imaging area (diagonal length) 4.5mm

Surface number RD Nd Vd
1 * -7.951 0.50 1.49700 81.54
2 * 9.240 D1
3 (Aperture) ∞ 0.30
4 * 2.042 1.32 1.52542 55.78 (plastic lens)
5 * -3.427 0.23
6 * -97.277 1.08 1.60687 27.03 (plastic lens)
7 * 1.561 D2
8 * -65.860 1.07 1.52542 55.78 (plastic lens)
9 * -4.157 2.05
10 ∞ 0.50 1.51633 64.14
11 ∞ 0.50
12 (imaging surface) ∞
* Aspherical

Aspheric coefficient Surface number R k
1 -7.951 0.7471
A4 A6 A8 A10
-1.4226E-03 6.5133E-04 -4.6454E-05 8.7004E-07

Surface number R k
2 9.240 -8.0216
A4 A6 A8 A10
-3.3136E-03 1.2213E-03 -8.1474E-05 3.7344E-07

Surface number R k
4 2.0423 0.4278
A4 A6 A8 A10
-1.3528E-02 -1.1334E-03 -1.6795E-03 -1.0532E-03

Surface number R k
5 -3.4268 -0.3099
A4 A6 A8 A10
1.7843E-02 6.9048E-04 -9.8864E-03 2.6979E-03

Surface number R k
6 -97.2767 0.
A4 A6 A8 A10
-3.6225E-02 1.1625E-02 -1.6419E-02 5.0282E-03

Surface number R k
7 1.5611 -0.6338
A4 A6 A8 A10
-4.2511E-02 2.5540E-02 -4.8808E-03 1.7965E-04

Surface number R k
8 -65.8601 0.
A4 A6 A8 A10
1.1036E-02 -1.7247E-03 -1.9329E-05 1.4789E-05

Surface number R k
9 -4.1566 -6.0409
A4 A6 A8 A10
6.0114E-03 -1.7213E-03 -4.3832E-07 1.2409E-05

Zoom data

f 3.8 5.0 10.6
FNO 2.8 3.3 5.4
ω 31.85 ° 24.13 ° 12.15 °
D1 5.88 4.15 1.21
D2 0.56 1.60 6.51

Example 3
FIG. 5 is a cross-sectional view along the optical axis showing the configuration of the third embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. ing.. 6A, 6B, and 6C show the spherical aberration, astigmatism, and distortion of the zoom lens of FIG. 5 in the states of FIGS. 6A, 6B, and 5C, respectively. .

The zoom lens of the third embodiment includes, in order from the object side, a first group G1 having a negative refractive power, an aperture stop S, a second group G2 having a positive refractive power, and a third group having a positive refractive power. And G3. CG is a cover glass, and I is an image pickup surface of an electronic image pickup device such as a CCD.
The first group G1 is composed of a biconcave negative lens L11 having both aspheric surfaces, and the second group G2 is an image side having both surfaces aspheric with a biconvex positive lens L21 having both surfaces aspheric. The third lens group G3 is composed of a positive meniscus lens L31 having a concave surface facing the object side, both surfaces of which are aspheric surfaces. A zoom method is employed in which the distance between the first group G1 and the second group decreases and the distance between the second group G2 and the third group G3 increases when the magnification is doubled.
The first group G1 moves along a locus convex toward the image side, the second group G2 always moves toward the object side together with the aperture stop S, and the third group G3 is fixed.

Numerical data 3
Focal length (f) 3.8mm ~ 10.6mm
F number (FNO) 2.8-5.4
Angle of view (2ω) 63.6 ° ~ 24.5 °
Effective imaging area (diagonal length) 4.5mm

Surface number RD Nd Vd
1 * -7.853 0.50 1.49700 81.54
2 * 9.085 D1
3 (Aperture) ∞ 0.30
4 * 2.108 1.32 1.51633 64.14
5 * -3.839 0.23
6 * 11.847 1.172 1.60687 27.03 (plastic lens)
7 * 1.428 D2
8 * -33.723 1.07 1.52542 55.78 (plastic lens)
9 * -3.956 1.94
10 ∞ 0.50 1.51633 64.14
11 ∞ 0.50
12 (imaging surface) ∞
* Aspherical

Aspheric coefficient Surface number R k
1 -7.853 0.9810
A4 A6 A8 A10
-1.4737E-03 6.5315E-04 -4.8254E-05 7.4343E-07

Surface number R k
2 9.085 -7.8939
A4 A6 A8 A10
-3.3009E-03 1.2166E-03 -8.4213E-05 -5.9356E-07

Surface number R k
4 2.108 0.4903
A4 A6 A8 A10
-1.1535E-02 -1.0013E-04 -1.0979E-03 -7.5035E-04

Surface number R k
5 -3.839 -1.0874
A4 A6 A8 A10
2.0121E-02 3.6737E-03 -9.2262E-03 2.0420E-03

Surface number R k
6 11.847 0.
A4 A6 A8 A10
-2.7733E-02 1.1102E-02 -1.7554E-02 4.4269E-03

Surface number R k
7 1.428 -0.6661
A4 A6 A8 A10
-4.2240E-02 1.9386E-02 -3.2246E-03 -1.5530E-03

Surface number R k
8 -33.7230 0.
A4 A6 A8 A10
1.0910E-02 -2.0296E-03 -8.5832E-05 1.7517E-05

Surface number R k
9 -3.9563 -5.1586
A4 A6 A8 A10
5.0166E-03 -1.9639E-03 -1.8925E-05 8.6882E-06

Zoom data

f 3.8 5.0 10.6
FNO 2.8 3.3 5.4
ω 31.83 ° 24.15 ° 12.27 °
D1 5.80 4.10 1.20
D2 0.59 1.58 6.28

Example 4
FIG. 7 is a cross-sectional view along the optical axis showing the configuration of a fourth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. ing.. 8A, 8B, and 8C show the spherical aberration, astigmatism, and distortion of the zoom lens in FIGS. 7A, 7B, and 7C, respectively. .

The zoom lens of the fourth embodiment includes, in order from the object side, a first group G1 having a negative refractive power, an aperture stop S, a second group G2 having a positive refractive power, and a third group having a positive refractive power. And G3. CG is a cover glass, and I is an image pickup surface of an electronic image pickup device such as a CCD.
The first group G1 is composed of a biconcave negative lens L11 having both aspheric surfaces, and the second group G2 is a biconvex positive lens L21 having both surfaces aspheric and an image side surface having an aspheric surface with an air gap in between. The third lens group G3 is composed of a positive meniscus lens L31 having a concave surface facing the object side whose image side surface is aspherical, and is used for zooming from the wide-angle end to the telephoto end. A zoom method is employed in which the distance between the first group G1 and the second group decreases and the distance between the second group G2 and the third group G3 increases.
The first group G1 moves along a locus convex toward the image side, the second group G2 always moves toward the object side together with the aperture stop S, and the third group G3 is fixed.

Numerical data 4
Focal length (f) 3.7mm ~ 10.1mm
F number (FNO) 2.8-5.3
Angle of view (2ω) 65.5 ° ~ 24.6 °
Effective imaging area (diagonal length) 4.5mm

Surface number RD Nd Vd
1 * -9.540 0.50 1.52542 55.80 (plastic lens)
2 * 7.264 D1
3 (Aperture) ∞ 0.30
4 * 2.328 1.11 1.48749 70.23
5 * -3.540 1.65
6 -7.568 0.50 1.60686 27.04 (Plastic lens)
7 * 2.371 D2
8 -80.915 1.45 1.52542 55.80 (plastic lens)
9 * -2.771 0.35
10 ∞ 0.50 1.51633 64.14
11 ∞ 0.50
12 (imaging surface) ∞
* Aspherical

Aspheric coefficient Surface number R k
1 -9.540 0.
A4 A6 A8
-1.9086E-02 4.9653E-03 -3.5838E-04

Surface number R k
2 7.264 0.
A4 A6 A8
-2.0726E-02 5.9923E-03 -3.1807E-04

Surface number R k
4 2.328 -1.9712
A4 A6
7.5983E-03 -8.6524E-04

Surface number R k
5 -3.540 0.
A4 A6 A8
1.1441E-02 -1.5539E-03 1.0720E-04

Surface number R k
7 2.371 2.1787
A4 A6 A8
-1.7149E-02 4.6266E-03 -8.1781E-03

Surface number R k
9 -2.771 -5.2351
A4 A6 A8
-2.1273E-03 -1.1166E-03 8.9849E-05

Zoom data

f 3.7 5.0 10.1
FNO 2.8 3.3 5.3
ω 32.78 ° 23.70 ° 12.32 °
D1 5.55 3.83 1.28
D2 0.89 1.73 5.15

Example 5
FIG. 9 is a cross-sectional view along the optical axis showing the configuration of a fifth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. ing.. FIGS. 10A, 10B, and 10C show the spherical aberration, astigmatism, and distortion of the zoom lens shown in FIG. 9, respectively, in the respective states (a), (b), and (c). .

The zoom lens of Example 5 includes, in order from the object side, a first group G1 having a negative refractive power, an aperture stop S, a second group G2 having a positive refractive power, and a third group having a positive refractive power. And G3. CG is a cover glass, and I is an image pickup surface of an electronic image pickup device such as a CCD.
The first group G1 is composed of a biconcave negative lens L11 having both aspheric surfaces, and the second group G2 is a biconcave having both surfaces aspheric with a biconvex positive lens L21 having both surfaces aspheric. The third lens unit G3 includes a negative lens L22. The third lens group G3 includes a biconvex positive lens L31 in the vicinity of the optical axis whose both surfaces are aspheric surfaces. A zoom method is employed in which the distance between the first group G1 and the second group decreases, and the distance between the second group G2 and the third group G3 increases.
The first group G1 moves along a locus convex toward the image side, the second group G2 always moves toward the object side together with the aperture stop S, and the third group G3 is fixed.

Numerical data 5
Focal length (f) 3.8mm ~ 10.5mm
F number (FNO) 2.8-5.4
Angle of view (2ω) 63.8 ° ~ 24.1 °
Effective imaging area (diagonal length) 4.5mm


Surface number RD Nd Vd
1 * -11.831 0.50 1.49700 81.54
2 * 6.858 D1
3 (Aperture) ∞ 0.30
4 * 1.911 1.32 1.52542 55.78 (plastic lens)
5 * -3.294 0.23
6 * -9.724 1.05 1.60687 27.03 (plastic lens)
7 * 1.720 D2
8 * 146.052 1.18 1.69100 54.82
9 * -5.882 2.01
10 ∞ 0.50 1.51633 64.14
11 ∞ 0.49
12 (imaging surface) ∞
* Aspherical

Aspheric coefficient Surface number R k
1 -11.8310 0.7505
A4 A6 A8 A10
-3.0131E-03 -8.0295E-05 1.9229E-04 -1.7195E-05

Surface number R k
2 6.8577 -8.0068
A4 A6 A8 A10
-1.2875E-03 -5.4296E-04 4.2774E-04 -3.6982E-05

Surface number R k
4 1.9110 0.4017
A4 A6 A8 A10
-1.0944E-02 -3.5790E-03 1.7809E-04 -9.6814E-04

Surface number R k
5 -3.2935 -0.3103
A4 A6 A8 A10
1.7853E-02 7.5270E-03 -1.0390E-02 3.7988E-03

Surface number R k
6 -9.7235 0.
A4 A6 A8 A10
-4.5896E-02 1.6389E-02 -1.3073E-02 4.8923E-03

Surface number R k
7 1.7201 -0.6318
A4 A6 A8 A10
-4.2907E-02 3.5560E-02 -1.1336E-02 7.1005E-03

Surface number R k
8 146.0517 0.
A4 A6 A8 A10
1.0643E-02 -2.9194E-03 1.0575E-04 2.7686E-05

Surface number R k
9 -5.8822 -6.0465
A4 A6 A8 A10
8.7300E-03 -1.7994E-03 -2.8530E-04 5.9468E-05

Zoom data

f 3.8 5.0 10.5
FNO 2.8 3.3 5.4
ω 31.91 ° 24.50 ° 12.07 °
D1 5.88 4.15 1.21
D2 0.55 1.61 6.49

Next, Table 1 shows numerical values calculated for the conditional expressions (1) to (11) in each example.

The zoom lens of the present invention described above can be applied by being incorporated in an electronic device such as a digital camera, a video camera, a digital video unit, a personal computer, a mobile computer, a mobile phone, and an information portable terminal.
For example, the zoom lens of the present invention can be suitably used in an imaging apparatus that forms an object image and receives the image on a solid-state imaging device such as a CCD, and particularly in an imaging optical system of a mobile phone. The embodiment is illustrated below.

FIG. 11 shows an example in which the zoom lens of the present invention is incorporated in a mobile phone that is convenient to carry.
11A is a front view of the mobile phone 400, FIG. 11B is a side view, and FIG. 11C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 11A to 11C, a mobile phone 400 includes a microphone unit 401 that inputs an operator's voice as information, a speaker unit 402 that outputs a voice of a call partner, and an operator who receives information. An input dial 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (not shown) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes the objective optical system 100 including the zoom lens of the present invention disposed on the photographing optical path 407, a shutter mechanism 150, and an image sensor chip 162 that receives an image. These are built in the mobile phone 400.
Here, an lR cut filter 180 is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 101 of the objective optical system 100 with one touch. Therefore, it is not necessary to align the center of the objective optical system 100 and the image sensor chip 162 and to adjust the surface interval, and the assembly is simple. Further, a cover glass 102 for protecting the objective optical system 100 is disposed at the tip (not shown) of the lens frame 101. The zoom lens driving mechanism in the lens frame 101 is not shown.
The object image received by the imaging element chip 162 is input to the processing means (not shown) via the terminal 166 and displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted.

Next, FIGS. 12 to 14 are conceptual diagrams showing a configuration in which the zoom lens of the present invention is built in a personal computer which is another example of the information processing apparatus.
12 is a front perspective view with the cover of the personal computer 300 opened, FIG. 13 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 14 is a side view of the state of FIG. As shown in FIGS. 12 to 14, the personal computer 300 includes a keyboard 301 for a writer to input information from the outside, information processing means and recording means not shown, and a monitor for displaying information to the operator. 302 and a photographing optical system 303 for photographing the operator himself and surrounding images. Here, the monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.
The photographing optical system 303 has an objective optical system 100 including a variable magnification optical system according to the present invention, a shutter mechanism 150, and an image sensor chip 162 that receives an image on a photographing optical path 304. These are built in the personal computer 300.
Here, an lR cut filter 180 is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 101 of the objective optical system 100 with one touch. Therefore, it is not necessary to align the center of the objective optical system 100 and the image sensor chip 162 and to adjust the surface interval, and the assembly is simple. Further, a cover glass 102 for protecting the objective optical system 100 is disposed at the tip (not shown) of the lens frame 101. The zoom lens driving mechanism in the lens frame 101 is not shown.
The object image received by the image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166 and displayed on the monitor 302 as an electronic image. FIG. A rendered image 305 is shown. The image 305 can also be displayed on the personal computer of the communication partner from a remote location via the processing means, the Internet, or the telephone.

15 to 17 are conceptual diagrams of a configuration in which the zoom lens of the present invention is incorporated in the photographing optical system 41 of the electronic camera. 15 is a front perspective view showing the appearance of the electronic camera 40, FIG. 16 is a rear perspective view thereof, and FIG. 17 is a cross-sectional view showing the configuration of the electronic camera 40. In this example, the electronic camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter button 45, a flash 46, a liquid crystal display monitor 47, and the like. When the shutter button 45 disposed on the upper side is pressed, the shutter mechanism 150 is driven in conjunction with the shutter button 45, and photographing is performed through the photographing optical system 41. An object image formed by the photographing optical system 41 is formed on the imaging surface 50 of the CCD 49 via a filter 51 such as a low-pass filter or an infrared cut filter. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 52. In addition, the processing means 52 is provided with a memory or the like, and can record a captured electronic image. This memory may be provided separately from the processing means 52, or may be configured to perform recording and writing electronically using a floppy (registered trademark) disk or the like.
Further, a finder objective optical system 53 is disposed on the finder optical path 44. The object image formed on the imaging surface 67 formed by the finder objective optical system 53 is formed on the field frame 57 of the Porro prism 55 which is an image erecting member. The field frame 57 separates the first reflecting surface 56 and the second reflecting surface 58 of the Porro prism 55 and is disposed therebetween. Behind this polyprism 55 is an eyepiece optical system 59 that guides the erect image to the observer eyeball E. Cover members 54 are disposed on the entrance surface of the photographic optical system 41 and the objective optical system 53 for the viewfinder and the exit surface of the eyepiece optical system 59, respectively.
The camera 40 configured in this way is a zoom lens having a high zoom ratio and a high zoom ratio in the photographing objective optical system 48, so that high performance can be realized and the number of the photographing objective optical system 48 is small. Since it can be constituted by an optical member, it is possible to realize downsizing and cost reduction.
In the configuration of FIG. 17, a parallel plane plate is arranged as the cover member 54, but a lens having power may be used.

Next, FIG. 18 shows a conceptual diagram of a configuration in which the zoom lens of the present invention is incorporated in the photographing objective optical system 48 of the photographing unit of the electronic camera 40. In this case, the zoom lens according to the present invention is used for the photographing objective optical system 48 disposed on the photographing optical path 42. An object image formed by the photographing objective optical system 48 is formed on the imaging surface 50 of the CCD 49 through a filter 51 such as a low-pass filter or an infrared cut filter. The object image received by the CCD 49 is displayed as an electronic image on a liquid crystal display element (LCD) 60 via the processing means 52. The processing means 52 also controls the recording means 61 that records the object image taken by the CCD 49 as electronic information. The image displayed on the LCD 60 is guided to the observer eyeball E through the eyepiece optical system 59. The eyepiece optical system 59 is composed of a decentered prism. In this example, the eyepiece optical system 59 is composed of three surfaces: an incident surface 62, a reflecting surface 63, and a combined reflecting / refracting surface 64. In addition, at least one of the two reflecting surfaces 63 and 64, preferably both surfaces, provides power to the light beam and has a single symmetry plane that corrects decentration aberrations. It consists of a curved surface. The only symmetry plane is formed on substantially the same plane as the only symmetry plane of the plane-symmetric free-form surface included in the prisms 10 and 20 of the photographing objective optical system 48.
The camera 40 configured in this manner is a zoom lens having a high zoom ratio and a high aberration ratio in the photographing optical system 41, so that high performance can be realized and the photographing optical system 41 is configured with a small number of optical members. Therefore, downsizing and cost reduction can be realized.
In this example, a plane parallel plate is disposed as the cover member 65 of the photographing objective optical system 48, but a lens having power may be used as in the previous example.
Here, without providing the cover member, the surface disposed closest to the object side in the zoom lens of the present invention can also be used as the cover member. In this example, the most object side surface is the entrance surface of the first lens group G1.

FIG. 3 is a cross-sectional view taken along the optical axis showing the configuration of the first embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. . (A), (b), and (c) respectively show spherical aberration, astigmatism, and distortion in each state of (a), (b), and (c) of the zoom lens of FIG. FIG. 3 is a cross-sectional view taken along the optical axis showing the configuration of a second embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. . (A), (b), and (c) respectively show spherical aberration, astigmatism, and distortion in each state of (a), (b), and (c) of the zoom lens of FIG. FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a third embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. . (A), (b), and (c) respectively show spherical aberration, astigmatism, and distortion in each state of (a), (b), and (c) of the zoom lens of FIG. FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a fourth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. . (A), (b), and (c) respectively show spherical aberration, astigmatism, and distortion in each state of (a), (b), and (c) of the zoom lens of FIG. FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a fifth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. . (A), (b), and (c) respectively show spherical aberration, astigmatism, and distortion in each state of (a), (b), and (c) of the zoom lens of FIG. FIGS. 2A and 2B show an example in which the zoom lens of the present invention is built in a mobile phone, in which FIG. 1A is a front view, FIG. 2B is a side view, and FIG. It is the front perspective view which opened the cover of the personal computer incorporating the zoom lens of this invention. It is sectional drawing of the imaging optical system built in the personal computer shown in FIG. It is a side view of the personal computer shown in FIG. It is a front perspective view which shows the external appearance of the electronic camera incorporating the zoom lens of this invention. FIG. 16 is a perspective view of the electronic camera shown in FIG. 15. It is sectional drawing which shows the internal structure of the electronic camera shown in FIG. It is a conceptual diagram of the structure which incorporated the zoom lens of this invention in the objective optical system for imaging | photography of the imaging | photography part of an electronic camera.

Explanation of symbols

G1 1st lens group G2 2nd lens group G3 3rd lens group CG Cover glass I Imaging surface of image sensor S Brightness diaphragm L11, L21, L22, L31, Lens E Observer eyeball 40 Camera 41 Imaging optical system 42 For imaging Optical path 43 Viewfinder optical system 44 Viewfinder optical path 45 Shutter button 46 Flash 47 LCD monitor 49 CCD
DESCRIPTION OF SYMBOLS 50 Imaging surface 51 Filter 52 Processing means 53 Finder objective optical system 54, 65 Cover member 55 Porro prism 56 1st anti-slope 57 Field frame 58 2nd reflective surface 59 Eyepiece optical system 60 LCD
61 Recording means 62 Incident surface 63, 64 Reflecting surface 66 Cover member 67 Imaging surface 100 Objective optical system 101 Mirror frame 102 Cover glass 150 Shutter 160 Imaging unit 162 Imaging element chip 166 Terminal 180 IR cut filter 300 Personal computer 301 Keyboard 302 Monitor 303 , 405 Imaging optical system 304, 407 Imaging optical path 305 Image 400 Mobile phone 401 Microphone unit 402 Speaker unit 403 Input dial 404 Monitor 406 Antenna

Claims (20)

In order from the object side, there are a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power. The third group performs zooming by changing between the groups. A zoom lens,
The first group of negative refractive power is composed of one negative lens, and the second group of positive refractive power is composed of one positive lens and one negative lens in order from the object side, and the positive refractive power The third group consists of one positive lens,
A three-group zoom lens, wherein a group interval between the first group and the second group satisfies the following condition.
1.2mm ≤ D12t ≤ 3.0mm
D12t is the distance between the first group and the second group at the telephoto end. In order from the object side, there are a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. A three-group zoom lens that performs
The first group of negative refractive power is composed of one negative lens, and the positive second group is composed of one positive lens and one negative lens in order from the object side, and the third group of positive refractive power. The group consists of one positive lens,
A three-group zoom lens characterized in that an interval between the aperture stop and the second group satisfies the following condition.
0.3mm ≤ Ds2t ≤ 1.2mm
Here, Ds2t is the distance between the aperture stop and the second group at the telephoto end.   The three-group zoom lens according to claim 2, wherein a shutter mechanism is disposed in the vicinity of the aperture stop.   The three-group zoom lens according to claim 3, wherein the shutter mechanism is a mechanical shutter. In order from the object side, there are a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. A three-group zoom lens that performs
The first group of negative refractive power is composed of one negative lens, and the second group of positive refractive power is composed of one positive lens and one negative lens in order from the object side, and the positive refractive power The third group consists of one positive lens,
A three-group zoom lens characterized in that an interval between the aperture stop and the second group satisfies the following condition.
1.2mm ≤ D12t ≤ 3.0mm
0.3mm ≤ Ds2t ≤ 1.2mm
Here, D12t is the distance between the first group and the second group at the telephoto end, and Ds2t is the distance between the stop and the second group at the telephoto end. 6. The three-group zoom lens according to claim 1, wherein the air lens in the second group satisfies the following condition.
-5.0 <(r5 + r6) / (r5-r6) <2.0
Here, r5 is the radius of curvature of the image side surface of the second lens group positive lens, and r6 is the radius of curvature of the object side surface of the second lens group negative lens. The three-group zoom lens according to any one of claims 1 to 6, wherein the negative lens constituting the second group satisfies the following condition.
0.1 <r7 / fw ≤ 1.1
Here, r7 is the radius of curvature of the surface closest to the image side of the negative lens constituting the second group, and fw is the focal length of the entire system at the wide angle end. 8. The three-group zoom lens according to claim 1, wherein an Abbe number νd1 of the negative lens in the first group satisfies the following condition.
50 <νd1 9. The three-group zoom lens according to claim 1, wherein an Abbe number νd2 of the positive lens constituting the second group satisfies the following condition.
50 <νd2 10. The three-group zoom lens according to claim 1, wherein a refractive index N2P of a positive lens constituting the second group satisfies the following condition.
1.5 <N2P   11. The three-group zoom lens according to claim 1, wherein the positive lens constituting the third group is coated with an infrared cut function coating.   12. The three-group zoom lens according to claim 1, wherein the third group is composed of a single glass lens.   The three-group zoom lens according to any one of claims 1 to 12, wherein each of the first group and the second group includes at least one glass lens.   The three-group zoom lens according to any one of claims 1 to 13, wherein at least one plastic lens is used. 15. The three-group zoom lens according to claim 1, wherein the positive lens in the third group satisfies the following conditional expression.
0.3 <(r8 + r9) / (r8-r9) <3.0
Here, r8 and r9 are the radii of curvature of the object-side surface and the image-side surface of the third group positive lens, respectively. 16. The three-group zoom lens according to claim 1, wherein the second group satisfies the following conditional expression.
0.8 <f2 / fw <1.6
Here, f2 is the focal length of the second group, and fw is the focal length of the entire system at the wide angle end. 17. The three-group zoom lens according to claim 1, wherein the third group satisfies the following conditional expression.
1.3 <f3 / fw <4.0
Here, f3 is the focal length of the third lens unit, and fw is the focal length of the entire system at the wide angle end.   18. The three-group zoom lens according to claim 1, wherein focusing is performed by moving the first group.   18. The three-group zoom lens according to claim 1, wherein focusing is performed by moving the third group. A three-group zoom lens according to any one of claims 1 to 19 and an image sensor disposed on an image side thereof, wherein a total thickness G2L of lenses constituting the second group is expressed by the following conditional expression: An imaging apparatus characterized by being satisfied.
0.6 <(G2L) / Y '<1.16
However, Y ′ is half the diagonal length of the effective imaging area of the imaging device.