JPH07239452A - Variable power optical system having vibrationproof function - Google Patents

Abstract

PURPOSE:To obtain a variable power optical system having a vibrationproof function constituted to obtain a static image by optically correcting the blur of the photographed image when a variable power optical system vibrates. CONSTITUTION:The first group L1 of the variable power optical system provided with the first group L1 which varies the power from a variable power part to an object side and is fixed at the time of focusing has two lens groups, the eleventh group L11 of a positive refracting power having an aspherical face of a shape successively weakening positive refracting power as porting further from the center of the lens to the peripheral part and the twelfth group L12 of the positive refracting power. The first group L1 corrects the blur of the photographed image when the variable power optical system vibrates by displacing the twelfth group L12 in a direction orthogonal with the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable power optical system having an image stabilizing function, and more particularly, by changing a part of the first lens unit on the object side in the direction orthogonal to the optical axis. It has an anti-vibration function suitable for photographic cameras, video cameras, etc. that stabilizes the captured image by optically correcting the blur of the captured image when the optical system vibrates (tilts) to obtain a still image. The present invention relates to a variable power optical system.

[0002]

2. Description of the Related Art When an image is captured from a moving object such as a car or an airplane in progress, vibration is transmitted to the image capturing system and the captured image is blurred.

Conventionally, various anti-vibration optical systems having a function of preventing blur of a photographed image have been proposed.

For example, in Japanese Examined Patent Publication No. 56-21133, some optical members are moved in a direction of canceling the vibrational displacement of an image due to vibration in accordance with an output signal from a detection means for detecting a vibration state in an optical device. By doing so, the image is stabilized.

In Japanese Patent Application Laid-Open No. 61-223819 and Japanese Patent Application Laid-Open No. 2-309329, the apex of the refractive variable apex prism in response to the vibration of the imaging system in a photographing system in which a refractive variable apex prism is arranged. The image is stabilized by changing the angle and deflecting the image.

In Japanese Patent Laid-Open No. 3-96931, image pickup signals are subjected to image processing to correct blur of a picked-up image. In Japanese Laid-Open Patent Publication No. 3-260615, the blur of a captured image is corrected by integrally spatially keeping the optical system and the imaging surface stationary.

In Japanese Unexamined Patent Publication No. 63-115126, the vibration of the photographing system is detected by using an acceleration sensor or the like, and a part of the lens group of the photographing system is orthogonal to the optical axis according to the signal obtained at this time. There is also a method of obtaining a still image by vibrating the camera.

In addition, in Japanese Patent Laid-Open No. 2-238429 and US Pat. No. 2,959,088, the first refractive power is negative and the first is negative.
A lens system composed of two lens groups, a first lens group and a second lens group, is arranged in front of the photographing system, and when the photographing system vibrates, the second lens group is used as a vibration-proof operation lens group, and a gimbal is supported at its focal position. We propose a vibration-proof optical system using the inertial pendulum method.

[0009]

In general, a vibration proof optical system is arranged in front of a photographing system, and a movable lens group of a part of the vibration proof optical system is vibrated to eliminate a blur of a photographed image to obtain a still image. However, there is a problem that the entire apparatus becomes large and the moving mechanism for moving the movable lens group becomes complicated.

There is also a problem that the amount of decentration aberrations generated when the movable lens group is vibrated is increased and the optical performance is significantly deteriorated.

In an optical system which uses a variable apex angle prism for image stabilization, there is a problem that the amount of eccentric magnification chromatic aberration is increased during image stabilization, especially on the long focal length side (telephoto side).

On the other hand, in an optical system for performing image stabilization by decentering a part of the lenses of the photographing system in the direction perpendicular to the optical axis, there is an advantage that no special optical system is required for image stabilization. However, on the other hand, there is a problem that the amount of eccentric aberration generated during image stabilization increases.

Further, in order to secure a necessary amount of light on the image pickup surface during image stabilization, the lens diameter of the lens group on the object side of the movable lens group must be increased, which leads to an increase in size of the entire apparatus. There was a problem.

In the present invention, a part of the lens group of the variable power optical system is displaced in the direction orthogonal to the optical axis to correct the blurring of the image when the variable power optical system vibrates (tilts). Thus, it is an object of the present invention to provide a variable power optical system having a vibration reduction function that suppresses the amount of decentering when the lens group is decentered while reducing the size of the entire apparatus, and that eccentric aberration is well corrected. .

[0015]

A variable power optical system having an image stabilizing function according to the present invention comprises (1-1) a first lens unit which is fixed at the time of zooming and focusing from the zooming portion to the object side. A variable power optical system provided, wherein the first lens unit has an aspherical surface having a shape in which the positive refractive power becomes weaker from the lens center to the peripheral portion, and the positive refractive power lens unit 11 has a positive refractive power. No. 12 group of two lens groups, and the blur of the captured image when the variable power optical system vibrates is corrected by displacing the twelfth group in the direction orthogonal to the optical axis. Is characterized by.

In particular, the variable power section has a second lens unit having a negative refractive power having a variable power function, and at least one lens unit fixed or moving at the time of variable power, and the second lens unit. It is characterized in that at least one of the lens groups provided closer to the image plane is moved on the optical axis to focus an object at a finite distance.

(1-2) A variable power optical system having a first lens unit having a positive refractive power, which moves in order from the object side during zooming, and a variable power portion, wherein the first lens unit is the lens center. The first lens group 11 has a positive refractive power and the second lens group 12 has a positive refractive power. It is characterized in that the blur of the photographed image when the double optical system vibrates is corrected by displacing the twelfth group in the direction orthogonal to the optical axis.

In particular, the variable power portion has a second lens unit of negative refractive power having a variable power function, and at least one lens unit that is fixed or moves at the time of variable power, and the second lens unit. It is characterized in that at least one of the lens groups provided closer to the image plane is moved on the optical axis to focus an object at a finite distance.

(1-3) When zooming in order from the object side, the first group of positive refracting power, which is a moving or fixed lens, the second group of negative refracting power having a zooming function, and the first group of positive refracting power. The third lens unit has a fourth lens unit having a positive refractive power, and the fourth lens unit has a fourth lens unit, and the image plane that fluctuates due to zooming is corrected by moving the fourth lens unit on the optical axis to perform focusing. In the optical system, the first lens unit includes an eleventh lens unit having a positive refractive power and a twelfth lens unit having a positive refractive power, each of which has an aspherical surface whose positive refractive power becomes weaker from the lens center to the peripheral portion. Is characterized in that the blur of the photographed image when the variable magnification optical system vibrates is corrected by displacing the twelfth group in the direction orthogonal to the optical axis. .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing a paraxial refractive power arrangement of an optical system of Numerical Embodiment 1 described later of the present invention, and FIGS. 2 and 3 are sectional views of lenses of Numerical Embodiments 1 and 2 of the present invention. is there.

FIGS. 4 and 5 are aberration diagrams when the reference state at the wide-angle end (no blur) and the blur angle of 1 degree are corrected in Numerical Embodiment 1 of the present invention, and FIGS. 6 and 7 show the present invention. Numerical example 1 is a reference state at the telephoto end (no blurring) and aberration diagrams when a 1 ° blur angle is corrected. FIGS. 8 and 9 are reference states at the wide-angle end of Numerical example 2 of the present invention ( FIG. 10 and FIG. 11 are aberration diagrams obtained when a blur angle of 1 degree and a blur angle of 1 degree are corrected, and FIGS. 10 and 11 show a reference state (no blur) and a blur angle of 1 degree at the telephoto end of Numerical Example 2 of the present invention. FIG.

In the figure, L1 is a first lens unit having a positive refractive power, which is moved or fixed during zooming, and has two lens units L11 and L12 having a positive refractive power. In addition, when changing the magnification, FIG.
In Numerical Embodiment 1 of FIG. 3, the first lens unit L1 is fixed, and in Numerical Embodiment 2 of FIG. 3, the first lens unit L1 moves as indicated by arrow C. First
The lens group L11 of the group L1 has an aspherical surface having a shape in which the positive refractive power is weakened from the lens center to the peripheral portion. The lens unit L12 is displaceable in the direction orthogonal to the optical axis in order to correct the blur of the captured image when the variable power optical system vibrates.

L2 is a second lens unit having a negative refractive power which moves along the optical axis direction for zooming. The second group L2 is, for example, an arrow a
It is moved as shown to zoom from the wide-angle end to the telephoto end. L3 is a third lens unit having a fixed positive refractive power, and L4 is a positive refractive power having both a function of correcting an image surface for correcting an image surface that changes with zooming and a function of focusing. Fourth
It is a group.

In this embodiment, when zooming from the wide-angle end to the telephoto end with the fourth lens unit L4 focused on an object at infinity or a near object, a curve b having a convex surface on the object side is used. It is moved on the optical axis like this.

G is a glass block such as a face plate and a filter. IP is the image plane.

In the variable power optical system according to the present invention, a lens group (correction lens group) L12 as an image stabilizing system is driven (displaced) in the direction perpendicular to the optical axis to correct an image blur when the variable power optical system vibrates. is doing. Now, when the entire imaging system is tilted by an angle θ, the image blur Δy ′ on the image plane is Δy ′ = f · tan θ, where f is the focal length of the entire optical system.

Further, when an arbitrary lens group ν is decentered by Eν in the direction perpendicular to the optical axis, the amount of displacement Δy ′ _a of the image on the image plane is
Is calculated by the following formula.

Δy ′ _a = sν · Eν where sν is called eccentricity sensitivity. Generally, the image stabilization system corrects the image blur caused by the movement of the image pickup system by the action of the image movement due to the eccentricity. The decentering sensitivity sν is proportional to the refractive power of the decentering lens unit and the height at which paraxial rays are incident on this lens unit.

In the present invention, in order to set the decentering sensitivity at this time to a desired value, the eleventh lens unit L11 is arranged on the object side of the twelfth lens unit L12 for eccentricity and is incident on the ν lens unit (lens unit L12). It changes the rays of light it does.

When a negative lens is arranged as the 11th lens unit L11, the decentering sensitivity becomes high and the shift amount (decentering amount) of the correction lens system becomes small, but the diameter of the correction lens system becomes large because divergent light enters. growing. On the contrary, when the positive lens is arranged, the decentering sensitivity becomes low and the shift amount of the correction lens system becomes large, but the diameter of the correction lens system becomes small because the convergent light enters.

Generally, if the amount of eccentricity of the correction lens system becomes too small, correction remains due to friction in mechanical control, which causes malfunction. Therefore, in the present invention, the eleventh
A positive lens is used as the group L11 to reduce the decentering sensitivity,
In addition, vibration reduction is performed with a predetermined shift amount (amount of eccentricity) while reducing the size of the optical system.

The decentration aberration newly generated when the image blur is corrected is expressed by the linear combination of the aberration of the correction lens system and the aberration of the lens unit on the object side of the correction lens system. Therefore, in the present invention, at least one lens surface of the eleventh lens unit is provided with an aspherical surface having a shape in which the positive refracting power is weakened from the lens center to the peripheral portion, so that the correction lens system and the lens unit closer to the object than the correction lens system. By giving the opposite property in terms of aberration, the occurrence of decentration aberration is suppressed.

At this time, the eleventh lens group has a positive refractive power, but the aspherical surface acts so as to have a negative refractive power due to aberrations. The principle of suppressing the eccentric aberration is that the property of the aberration is a problem, so that even if the refracting power itself has an arbitrary value, it can be realized independently of the refracting power by introducing an aspherical surface.

In Numerical Example 1 of FIG. 2, the first lens surface is aspherical, counting from the object side. 11th at this time
Aberration coefficients of the first group and the twelfth group (spherical aberration SA, coma aberration C
Table 1 shows the values of O and astigmatism AS) obtained according to Yoshiya Matsui "Lens Design Method" (Kyoritsu Publishing KK).

[0035]

[Table 1] As shown in Table 1, although the 11th group and the 12th group both have positive refractive power, the first group is introduced by the introduction of the aspherical surface.
The first group and the twelfth group are designed so as to exhibit mutually opposite properties.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number. In the numerical examples, the last two lens surfaces are glass blocks such as face plates and filters.

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive light traveling direction, and R as paraxial curvature radii K, a, b, c, d, and e. When using spherical coefficient

[0038]

[Equation 1] It is expressed by (Numerical Example 1) F = 4.65 FNO = 1.85 to 2.80 2 ω = 55.6 ° to 6.04 ° R 1 = 21.42 D 1 = 3.00 N 1 = 1.60311 ν 1 = 60.7 R 2 = 37.20 D 2 = variable R 3 = 30.02 D 3 = 1.00 N 2 = 1.84666 ν 2 = 23.8 R 4 = 16.36 D 4 = 3.70 N 3 = 1.60311 ν 3 = 60.7 R 5 = 246.19 D 5 = 0.15 R 6 = 23.92 D 6 = 2.60 N 4 = 1.72000 ν 4 = 50.3 R 7 = 52.30 D 7 = 0.60 R 8 = 39.84 D 8 = 0.50 N 5 = 1.77250 ν 5 = 49.6 R 9 = 4.98 D 9 = 2.10 R10 = -11.55 D10 = 0.50 N 6 = 1.69680 ν 6 = 55.5 R11 = 8.35 D11 = 1.00 R12 = 9.81 D12 = 1.30 N 7 = 1.84666 ν 7 = 23.8 R13 = 37.67 D13 = Variable R14 = (Aperture) D14 = Variable R15 = 14.68 D15 = 2.75 N 8 = 1.58313 ν 8 = 59.4 R16 = -43.28 D16 = Variable R17 = 12.20 D17 = 0.50 N 9 = 1.84666 ν 9 = 23.8 R18 = 6.20 D18 = 0.08 R19 = 6.44 D19 = 3.40 N10 = 1.58313 ν10 = 59.4 R20 = -13.36 D20 = 3.00 R21 = ∞ D21 = 4.00 N11 = 1.51633 ν11 = 64.2 R22 = ∞

[0039]

[Table 2] Aspherical surface coefficient of the first surface r = + 21.427 k = 0 a = −6.58 × 10 ⁻⁶ b = −2.82 × 10 ⁻⁸ c = + 7.99 × 10 ⁻¹¹ d = −3.07 X10 ^-13 Aspherical coefficient of the fifth surface r = + 246.193 k = 0 a = -4.25 × 10 ^-6 b = -2.44 × 10 ^-8 c = + 1.22 × 10 ^-10 d = + 1.29 × 10 ⁻¹³ Aspherical surface coefficient of fifteenth surface r = + 14.684 k = + 3.18 b = −3.23 × 10 ⁻⁴ c = + 6.64 × 10 ⁻⁶ d = −6.49 × 10 ⁻⁷ e = + 1.43 × 10 ⁻⁸ Aspherical surface coefficient of the 20th surface r = −13.367 k = −6.64 b = + 3.22 × 10 ⁻⁴ c = + 2.01 × 10 ⁻⁵ d = −2.12 × 10 ⁻⁶ e = + 6.76 × 10 ⁻⁸ (Image stabilization amount) Moving amount of the twelfth lens unit L12 in the direction perpendicular to the optical axis: +0.68
mm to -0.68 mm Image movement amount W-edge (f = 4.65 mm): +0.08
mm to -0.08 mm T-end (f = 46.5 mm): +0.82 mm to -0.
82 mm (Numerical Example 2) F = 5.06 FNO = 1.85 to 2.8 2 ω = 51.6 ° to 5.9 ° R 1 = 20.25 D 1 = 3.00 N 1 = 1.60311 ν 1 = 60.7 R 2 = 33.52 D 2 = variable R 3 = 31.02 D 3 = 1.00 N 2 = 1.84666 ν 2 = 23.8 R 4 = 16.43 D 4 = 3.70 N 3 = 1.60311 ν 3 = 60.7 R 5 = 165.04 D 5 = 0.15 R 6 = 23.83 D 6 = 2.60 N 4 = 1.72000 ν 4 = 50.3 R 7 = 61.79 D 7 = 0.66 R 8 = 38.92 D 8 = 0.50 N 5 = 1.77250 ν 5 = 49.6 R 9 = 4.96 D 9 = 2.10 R10 = -11.78 D10 = 0.50 N 6 = 1.69680 ν 6 = 55.5 R11 = 8.47 D11 = 1.00 R12 = 9.76 D12 = 1.30 N 7 = 1.84666 ν 7 = 23.8 R13 = 34.61 D13 = Variable R14 = (Aperture) D14 = Variable R15 = 14.37 D15 = 2 .75 N 8 = 1.58313 ν 8 = 59.4 R16 = -39.52 D16 = Variable R17 = 11.89 D17 = 0.50 N 9 = 1.84666 ν 9 = 23.8 R18 = 6.19 D18 = 0.08 R19 = 6.44 D19 = 3.40 N10 = 1.58313 ν10 = 59.4 R20 = -12.81 D20 = 3.00 R21 = ∞ D21 = 4.00 N11 = 1.51633 ν11 = 64.2 R22 = ∞

[0040]

[Table 3] Aspherical surface coefficient of the first surface r = + 20.025 k = 0 a = -6.98 × 10 ^-6 b = -3.18 × 10 ^-8 c = + 1.01 × 10 ^-10 d = -3.07 Axial coefficient of the 5th surface of x10 ^-13 r = + 165.05 k = 0 a = -3.81x10 ^-6 b = -1.85x10 ^-8 c = + 1.28x10 ^-10 d = + 1.29 × 10 ⁻¹³ Aspherical surface coefficient of fifteenth surface r = + 14.371 k = + 2.76 b = −3.23 × 10 ⁻⁴ c = + 6.64 × 10 ⁻⁶ d = −6.49 × 10 ⁻⁷ e = + 1.42 × 10 ⁻⁸ Aspherical surface coefficient of 20th surface r = −12.813 k = −6.54 b = −3.22 × 10 ⁻⁴ c = + 2.01 × 10 ⁻⁵ d = −2.12 × 10 ⁻⁶ e = + 6.76 × 10 ⁻⁸ (anti-vibration correction amount) Moving amount in the optical axis vertical direction of the twelfth lens unit L12: +0.69
mm to -0.69 mm Image movement amount W-edge (f = 5.06 mm): +0.09
mm to -0.09 mm T-end (f = 47.6 mm): +0.83 mm to -0.
83 mm

[0041]

As described above, according to the present invention, an image when the variable power optical system vibrates (tilts) by displacing a part of the lens group of the variable power optical system in the direction orthogonal to the optical axis. By compensating for the camera shake, the overall size of the apparatus is reduced and the amount of eccentricity generated when the lens group is decentered is suppressed to a small amount. Double optics can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a paraxial refractive power arrangement according to Numerical Example 1 of the present invention.

FIG. 2 is a lens cross-sectional view of Numerical Example 1 of the present invention.

FIG. 3 is a lens cross-sectional view of Numerical Example 2 of the present invention.

FIG. 4 is an aberration diagram of a reference state at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 5 is an aberration diagram when a 1 ° blur angle is corrected at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 6 is an aberration diagram of a reference state at the telephoto end according to Numerical Example 1 of the present invention.

FIG. 7 is an aberration diagram when a 1 ° blur angle is corrected at the telephoto end according to Numerical Example 1 of the present invention.

FIG. 8 is an aberration diagram of a reference state at the wide-angle end according to Numerical Example 2 of the present invention.

FIG. 9 is an aberration diagram when a 1 ° blur angle is corrected at the wide-angle end according to Numerical Example 2 of the present invention.

FIG. 10 is an aberration diagram of a reference state at the telephoto end according to Numerical Example 2 of the present invention.

FIG. 11 is an aberration diagram when a 1 ° blur angle is corrected at the telephoto end according to Numerical Example 2 of the present invention.

[Explanation of symbols]

 L1 1st group L11 11th group L12 12th group L2 2nd group L3 3rd group L4 4th group SP Aperture d d line g g line S Sagittal image surface M Meridional image surface

Claims (5)

[Claims] 1. A variable power optical system in which a fixed first lens unit is provided on the object side of the variable power lens unit during zooming and focusing, and the first lens unit is positive from the lens center toward the peripheral portion. When the variable power optical system vibrates, it has two lens groups, an eleventh lens group having a positive refractive power and an twelfth lens group having a positive refractive power, each of which has an aspherical surface having a weaker refractive power. The variable-magnification optical system having a vibration-proof function, characterized in that the blur of the photographed image is corrected by displacing the twelfth group in a direction orthogonal to the optical axis. 2. The zooming unit includes a second lens unit having a negative refractive power having a zooming function, and at least one lens unit fixed or moving during zooming. The anti-vibration function according to claim 1, wherein at least one of the lens groups provided closer to the image plane is moved along the optical axis to focus on an object of a finite distance. Variable magnification optical system possessed. 3. A variable power optical system having a first lens unit having a positive refractive power which moves in order from the object side during zooming and a variable power unit, wherein the first lens unit is located from a lens center to a peripheral portion. The variable power optical system has two lens groups, an eleventh lens group having a positive refractive power and an twelfth lens group having a positive refractive power, each of which has an aspherical surface whose positive refractive power becomes weaker as A variable-magnification optical system having a vibration-proof function, characterized in that the blur of a photographed image when the lens is vibrated is corrected by displacing the twelfth group in a direction orthogonal to the optical axis. 4. The variable power unit includes a second lens unit having a negative refractive power having a variable power function, and at least one lens unit that is fixed or moves at the time of variable power, and the second lens unit. 4. The image stabilizing function according to claim 3, wherein at least one of the lens groups provided closer to the image plane is moved on the optical axis to focus an object at a finite distance. Variable magnification optical system possessed. 5. A first lens unit having a positive refractive power which is moved or fixed, a second lens unit having a negative refractive power having a magnification changing function, and a third lens unit having a positive refractive power, which is movable or fixed in order from the object side. A variable power optical system having four lens groups of a fourth lens group having a positive refractive power, which corrects an image plane fluctuating due to zooming by moving the fourth lens group on the optical axis and performs focusing. Therefore, the first lens unit has two groups, a positive lens unit 11 having a positive refractive power and a lens unit 12 having a positive refractive power, which has an aspherical surface whose positive refractive power becomes weaker from the lens center to the peripheral portion. An anti-vibration function having a lens group and correcting blurring of a photographed image when the variable magnification optical system vibrates by displacing the twelfth group in a direction orthogonal to the optical axis. A variable power optical system having a.