JPS63115126A - Photographic lens with vibration-proof function - Google Patents

Abstract

PURPOSE:To set the movement quantity of a movable lens group consisting of a positive and a negative lens and the shift correction quantity of an image in proportional relation and to simplify a driving device by providing a fixed lens group and the movable lens, and setting specific condition between the focal length of the fixed lens and the focal length of the whole system. CONSTITUTION:The fixed lens group I and the movable lens group II consisting of at least one positive lens and one negative lens each which moves at right angles to an optical axis to correct the blurring of an image are provided at right angles to the optical axis. Then the absolute value of the focal length F1 of the lens group I is set >=4 times as large as the focal length FT of the whole system and an on-axis light beam which is incident on the lens group II through the lens group I is decreased. Further, 0.25FT<F2<0.8FT, and 43<nuP and nuN<40 hold for the focal length F2 of the lens group II, and the mean Abbe numbers nuP and nuN of the materials of the positive and negative lenses of the lens group II. Consequently, the movable lens is reduced in size and weight, the response is improved, and the movement quantity and correction quantity become proportional to each other, thereby simplifying the driving device.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a photographic lens having a function of correcting the precipitate of a photographed image due to vibration, a so-called anti-shake function, and in particular, to a compact and lightweight movable lens group for anti-shake. In addition to preventing the optical performance from deteriorating when the movable lens group is moved in a direction perpendicular to the optical axis to achieve a vibration-proofing effect, it also has a vibration-proofing function that improves the controllability of the actuator. This relates to photographic lenses.

(Prior Art) When attempting to photograph a moving object such as a moving car or aircraft, vibrations are transmitted to the photographing system and blurring occurs in the photographed image. The pre of the photographed image at this time becomes larger as the focal length of the photographing system becomes longer.

Conventionally, anti-vibration optical systems having a function of preventing blurring in photographed images have been proposed, for example, in Japanese Patent Publication No. 56-34847, Japanese Patent Publication No. 7414-1982, Japanese Patent Publication No. 7416-1987, and the like.

In these publications, an optical member that is spatially fixed against vibration is placed in a part of the imaging system, and by utilizing the prism effect generated in response to the vibration of this optical member, the photographed image is deflected onto the imaging plane. I am getting a still image.

In addition, an acceleration sensor built into the camera is used to detect the acceleration of the camera moved by an external force, and this value is integrated twice to determine the amount of movement. There is a method of obtaining a still image by using an actuator to vibrate the lens group in a direction perpendicular to the optical axis. As the actuator, for example, a meter configured to be able to vibrate independently of each other in two-dimensional directions or a stack of piezo elements can be used.

There is also a method in which the movement of a captured image formed on an image sensor such as a CCD is analyzed via an electrical processing system, and the signals obtained at this time are used to obtain a still image.

Generally, a mechanism for obtaining a still image by vibrating a part of the lens group of the photographing system to eliminate blur in the photographed image is required to have good responsiveness.

For this reason, we made the movable lens group as small and lightweight as possible, and also reduced its inertial mass. Furthermore, we simplified the relationship between the amount of image pre-correction and the amount of movement of the movable lens, and shortened the calculation time for conversion. A photography system is required.

In addition, there is a need for a photographing lens that exhibits less deterioration in optical performance when the movable lens group is moved in a direction perpendicular to the optical axis and placed in an eccentric state.

However, it is generally very difficult to obtain a photographic lens that satisfies all of these conditions, and in particular, moving a part of the lens group that has refractive power in the photographing system greatly deteriorates the optical performance, making it difficult to obtain good images. There was a drawback that I couldn't get it.

(Problems to be Solved by the Invention) The present invention aims to reduce the size and weight of the movable lens group when correcting image pretension by moving some of the lens groups of the photographic lens in a direction perpendicular to the optical axis. This improves responsiveness, and also simplifies the driving device by making the amount of movement of the movable lens group proportional to the amount of image misalignment correction. It is an object of the present invention to provide a photographic lens having an anti-vibration function that produces a small amount of aberrations and provides good optical performance.

(Means for solving the problem) Starting from the object side, there is a fixed lens group that is immovable in a direction perpendicular to the optical axis, and a movable lens group that corrects the pretension of the photographed image by moving in a direction perpendicular to the optical axis. 4FT, where the movable lens group is composed of at least one positive lens and at least one negative lens, and the focal lengths of the fixed lens group and the entire system are F + and F T, respectively. The condition is to satisfy the following condition: <IF, I (+).

(Example) 1st. Second. FIG. 3 is a cross-sectional view of lenses of numerical examples 1 to 3 of the present invention, respectively. On the right side of the figure, numeral 1 is a fixed lens group that does not move in the direction orthogonal to the optical axis, and 2 is a movable lens group that moves in the direction orthogonal to the optical axis to correct the image pre-position. It is assumed that the movable lens group (2) is driven by an actuator (not shown) as described above. F is a lens group for focusing.

In this embodiment, the movable lens group is composed of at least one positive lens and at least one negative lens, and the focal length of the fixed lens group is set as in the above-mentioned conditional expression (1), thereby correcting the pre-image. This allows for good performance and prevents deterioration in optical performance due to movement of the movable lens group.

In particular, in this embodiment, the focal path tlt F 1 of the fixed lens group
By setting the absolute value of i1 to be larger than 4 times the focal path of the entire system p'r, and reducing the incident angle αP of the axial ray when it passes through the fixed lens group and enters the movable lens group. , the deterioration in optical performance that occurs when correcting image pretension by moving the movable lens group is reduced.

Next, from an aberration theory standpoint, we will discuss the occurrence of decentering aberration when moving the movable lens group in the direction orthogonal to the optical axis to correct the image pretension in the refractive power arrangement of this embodiment.
The explanation will be based on the method presented by Gen Matsu at the Recycling Applied Physics Lecture (1962).

When some of the lens groups of the photographic lens are parallel decentered by E, the aberration amount Δ'Y of the entire system is as shown in equation (a), which is the aberration amount ΔY before decentering and the eccentric aberration amount ΔY (E
). Here, the eccentric aberration ΔY (E) is (b
) As shown in the formula, first-order eccentric comatic aberration (II E), first-order eccentric astigmatism (III E), first-order eccentric field curvature (PE), and first-order eccentric distortion aberration - (VEI). , the following eccentric distortion additional aberration (VE2), and the second-order eccentric astigmatism (IIIE'), and the second-order decentering & surface curvature (pε”
), second-order eccentric distortion aberration (VE21), second-order eccentric distortion additional aberration (VE22), and first-order origin shift (Δ
E), cubic origin movement (ΔE3). or
From equation (C) to equation (fil), (n E) ~ (ΔE3
) The aberrations up to ) are determined by adjusting the incident and exit angles of the light rays to the movable lens group by α2. α, it is expressed using the aberration coefficients Ip, Up, mp, Pp, and Vp of the movable lens group.

Δ'Y~ΔY+ΔY(ε)(a) 1-BshiralIJ)a:rsk fa (vr 't
) −Z (vt:'zl i< mtk (J(tt
zE") + (p1tsu),]-me;'(E(otE)stJ(ΔEtsu) (
b) (n E)・−α2■2+αPIP
(c) (mE) = −ap I[Ip + (Xp
nP (d) (PE) = −ap
Pp (e) (VEI)
= −ap Vp ”C!p mp
(f) (VE2) = −(IP Pp
(g) (III E2)・αP'1ll
P-2α2αpup÷αP2IP (h) (PE2)
・α, 2P, (1)(V
E21)-a, 2V p -2a, αP Ul,
+a, "■ 2 (j) (VE"2) -a P2a
PP P(k)(ΔE) ・-2(α°P−αp)
(1) (ΔE3) = −Qp'
(Qp Vp −ap(I[rp ” Pp))
+ 2αP αP (αPIII, -αP Tlp
)-ap” (ap up-ap Ip)
(m) (IIE) ”= αP Ip
(C') (III E)
勺 αpIIp (d
')(PE) LtO(e') (VEI) # ctP I[IP(f')(V
E2): -ap Pp
(g') (II[E2) Ri αP21p
(h') (PE2)
L90 (j'
) (VE21): ap'Hp
(j') (VE22) 4 0
(k') (ΔE) L
:r-2a'p (1'
) (ΔE3) Saki -αP3IP
(m') Here, if the refractive power of the fixed lens group is set as in conditional expression (1) above so that the incident angle α2 is small, then from equation (C) to equation (m), the incident angle is Since the term regarding αP can be ignored, (II
E) to (ΔE3) can be expressed from equation (Co) to equation (1).

From equation (c) to equation (k) regarding decentering aberration and (Co)
Comparing the equation (ko) from the equation, the eccentric coma affects the image quality.

To reduce the occurrence of decentered astigmatism and decentered curvature of field, reduce spherical aberration and comatic aberration of the movable lens group.

Astigmatism, Petzval sum, etc. must all be corrected to a small value, and generally many lenses are required. However, as in the present invention, the angle of incidence α.

If the configuration is such that the astigmatism and Petzval sum of the movable lens group related to eccentric distortion aberration will be reduced, if correction is made to mainly reduce spherical aberration and comatic aberration, a relatively good image will be obtained. is obtained. The present invention is configured so that the angle of incidence αP is small, thereby reducing the number of lenses in the movable lens group, making it easier to make the movable lens group smaller and lighter, reducing the load on the drive system, and further improving responsiveness. We are trying to improve.

In this embodiment, as described above, the movable lens group is composed of at least one positive lens and at least one negative lens, so that the spherical aberration and coma aberration of the movable lens group are reduced.

On the other hand, equation (b) 1112(E(ΔE)◆El(ΔE3
)) corresponds to the amount of image movement S when the movable lens group is moved by E in the direction perpendicular to the optical axis. Of these (ΔE3
) is large, the movement 11s cannot be ignored, and the movement 11s becomes a cubic equation, which makes drive control for correcting the pre-image complexity.

However, when the incident angle αP is configured to be small as in the present invention, (ΔE3) is expressed as equation (l"), but as mentioned above, the spherical aberration of the movable lens group is basically small. After all, it has been corrected so that
(ΔE3) can be ignored.

Therefore, in this embodiment, the amount of movement of the movable lens group and the amount of movement of the image plane are in a proportional relationship, which makes it possible to extremely easily control the drive of the movable lens group.

In the photographing lens of this embodiment, eccentric distortion is determined by the astigmatism of the movable lens group and the Petzval sum. In many cases, astigmatism and Petzval sum are small, so eccentric distortion can be tolerated in practice. However, as astigmatism and Petzval sum become large, eccentric distortion cannot be tolerated and becomes a cause of deterioration of image quality.

Therefore, in this embodiment, the focal length of the movable lens group is set to F.
2, 0.25F T < F 2 < 0.8F T ・
It is better to satisfy conditional expression (2).

Conditional expression (2) is intended to satisfactorily correct the astigmatism and Petzval sum of the movable lens group, and to reduce the occurrence of eccentric distortion aberration. If the refractive power of the movable lens group exceeds the lower limit and becomes too strong, eccentric distortion will occur more frequently, and if the refractive power exceeds the upper limit and becomes too weak, the amount of movement of the movable lens group will become too large and the drive system This is not a good idea as it increases the burden on people.

Furthermore, when the movable lens group is moved in a direction perpendicular to the optical axis to correct the pretension of the image as in this embodiment, a large amount of eccentric chromatic aberration corresponding to a type of lateral chromatic aberration occurs due to the prism effect of the movable lens group. There is.

Therefore, in this embodiment, the average value of the Abbe numbers of the materials of the positive lens and the negative lens in the movable lens group is set to ν2. It is best to set it as when ν.

If Conditional Expression (3) is not satisfied, the amount of eccentric chromatic aberration will increase, and the image quality will deteriorate significantly, which is not preferable.

In this embodiment, focusing is performed by moving all or part of the fixed lens group I, thereby reducing the amount of decentering aberrations that occur when focusing on various objects.

Next, numerical examples of the present invention will be shown. In numerical examples R
i is the radius of curvature of the first lens surface from the object side, D
i is the first lens thickness and air gap from the object side, Ni
and νi are the refractive index and Abbe number of the glass of the first lens, respectively, in order from the object side. However, N-1,40590,
υ-52,0 is silicone oil.

Numerical Example I F=300 FNo-1:2.8
2ω-18,25' Numerical Example 2F・300F
No=I:2.8 2ω-8, 25°RI-121,
99D l-16, 81N l-1, 433117
ν 1-95.112・-574,6802・1.
22R3 meals 119.61 D: 1-16.
30 N 2 So 1.49700 ν 2-8
1.6It 4- -432.30 0 4- 4
．． 21R5--318,0105-5,6083-1,
72047ν 3-34.7It 6- 278.
39 0 6-31.90R7-45,9007 meeting
6.11 N 4-1.58913 ν 4
-61. OR8-40,75D 8-17.40R9
--250,6:] D 9- 6.11
N S-1,805+8 ν 5-25.410
- -75.58 010- 2.55 N
6-1.61340 ν B-43, 11R11
-92,58DIl Snow 34.1BR12=285
．． 03 0r2- 5.40 8 7 meeting 1.749
50 v 7-35.3R1:l--118,0
5DI3- 2.55 88-1.82041 ν
8-60.314- 82.72 014-9
．． 015-2.55 N of 17rl+5-
9-t, 5+e3:+ Shi9-64.1 old 6 trout
ω 016-0.04 Nl0-1.40
590 ν 10-52.0R1711oo
DI7-3.97 N+1-1.47069
v 11=67.4 old 8--284.24 018
-0.51f119- 76.73 DI9117.
58 N12-1.61720 v 12-54.
0R20--115,26020-2,55N+3 So 1
．． 805+8 ν 13-25.4R21=
oo D21a14.27R22@
oo D22 2.55 N+4-1.
5!633 v 14-64. lR23 So
ψ D23-0.04 Nl5-1.405
90 Tsu 15-52. Or+24- o
o D24114.59 N+6-1.5
+633 v 16 64. lR25-■ Numerical Example 3 F=300 FNo-1: 2.8
2ω-8, 25°11 I-130, 31D
l-15,76N I-1,4:1387v
l-95,IR2--493,4502-0,70 R3-119,76D 3-18.54 N
2-1.49700 ν 2-81.6R4--4
53,3304-3,54 R5--334,0605-5,64N]-1,7
2047ν 3-34,711 B-308,370
6-31, 8: IR7-48, 2707-6, 20N
4-1.589+3 ν 4-61. OR8-4
2,32D 8-17.37R9--223,260
9-6,10N 5-1.8051+1 ν 5
m25.41110- -77.02 DIO-
2,54N 6-1.61:140 v 6-
43.8R11-93, 78Dll-35, 80RI2
- 618.33 DI2- 5.08 N
7-1.80610 ν 7・i0C(II
3- -81.10 013 So 3.05 N
8-1.60311 ν II-fiO,7R
14-83,07DI4-11.341115-
oo DI5-2. ．． 03 N 9
-1.51633 v 9-64. IRI6=
oo Dll-0,10Nl0-1.4059
0 v l0=52.0R17-CODI″1.-2
．． 03 Ni1-1.51633 v 11-64
．． 1R+8-ao 018-2.03
R19-133, 15019= 3.29 N1
2-1.72000 v 12-50.2R20
248.23 020-3.34R21--5
28,04021-2,91N13-1.80610
131140.9R22-1399.05 0
22 meals 0.11R23s 91.88 023
−7.92 N+4−1.57115 v
14-5: 1.0R24■ -79,67024-2
,58N+5-1.805+8 15-25.4
R25--237,78025-2,03R26-ao
D261I 2.03 N16-1.5
1633 v 16-64. lR27-co
D27-IO, 10N+7-1.40590
v 17-52.0R281co D28s
2.03 N18=1.51633v
18=64. lR29-■ In Numerical Example 1 shown in FIG. 1, the movable lens group (■) is composed of two lenses, a positive lens and a negative lens. In this example, two movable lens groups are used to correct the image pretension by 2 mm.
Even when the lens is moved by 11Iff+, as shown in FIG. 4, no eccentric aberration occurs at all, and good optical performance is maintained.

In addition, when the movable lens group is composed of a cemented lens of a positive lens and a negative lens as in this embodiment, when the radius of curvature of the lens surface on the object side and the image plane side is respectively rA+r8, 5-(
Setting the shape factor defined by ra + rA)/(ra − r A) as 0.35 < S < 1.5 (4) prevents the occurrence of decentering aberrations. Preferable to reduce.

If conditional expression (4) is not satisfied, eccentric aberration increases when the movable lens group is moved.

In Numerical Example 2 shown in FIG. 2, as shown in FIG. 7 with only this part taken out, a water-tight structure is placed in a cylinder sealed with a ninth lens Gl and a fourteenth lens G2, which are cover glasses, together with silicone oil L. Insert the movable lens group ■ stored in the tube, float the movable lens group ■, and activate the actuator AI.
, A2 are used to move the movable lens group (2). Another set of actuators is provided perpendicular to the drawing, and mutual interference is prevented by making the pressing rod flexible or by providing a relief in the direction perpendicular to the pressing direction in the communication part. . In this case, the movable lens group ■ requires a cover glass to seal the silicone oil, but in this example, the inertia of the movable lens group is Reducing mass.

In numerical example 3 shown in FIG.
A movable lens group (2) is provided together with silicone oil between the lens and the 16th lens, and the movable lens group (2) is moved by a method similar to that shown in FIG.

In this embodiment, the object of the present invention can also be achieved even if a filter or a lens group having weak refractive power is disposed behind the lens system.

Further, the present invention can also be applied to a shift lens.

(Effects of the Invention) According to the present invention, the movable lens group for correcting image pretension is made smaller and lighter, improving responsiveness, and the relationship between the amount of movement of the movable lens group and the amount of image pretension is proportional. In addition to simplifying the driving device by making the relationship between can do.

[Brief explanation of the drawing]

1st. Second. FIG. 3 shows numerical examples 1, 2, and 2 of the present invention, respectively.
3. Lens sectional view of No. 3, No. 4. Fifth. FIG. 6 is a diagram showing various aberrations of numerical examples 1 and 2.3 of the present invention, and FIG. 7 is an explanatory diagram of the drive system. The symbol in the figure is a fixed lens group, and the symbol ■ is a movable lens group. In the aberration diagrams, (^) is the aberration before the movable lens group is moved, and (B) is the aberration when the movable lens group is moved by 2 (mm). Further, Y is the image height, M is the meridional image plane, S is the sagittal image plane, d is the d-line, and g is the g-line. Patent applicant Canon Co., Ltd. 1st ■ Figure 2 ↓ Figure 3 ↓ 5k112 knee building t% ~ wt 箆G口(B) 82 Proceedings (spontaneous) Patented on April 3, 1986 Director-General of the Agency 2. Name of the invention Photographic lens with anti-vibration function 3. Relationship to the case of person who makes correction Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100)
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4, Agent's residence: 301 Jiyugaoka, Belheim, 2-17-3 Okusawa, Setagaya-ku, Tokyo 158 (Telephone: 718-5614) (1)
Column for detailed explanation of the invention in the specification (2) Drawing 6 attached to the application, content of amendments (1) "In addition, in this example" on page 13, line 17 of the specification In example (1), focusing is performed by extending the entire lens system. Numerical examples (
2) In (3), 10 ■ l. Indication of the case Patent Application No. 262115 of 1988 2. Name of the invention Photographic lens with anti-vibration function 3. Person who makes correction Relationship with the case Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4, Agent Residence 301 Jiyugaoka, Belheim, 2-17-3 Okusawa, Setagaya-ku, Tokyo 158 (Telephone: 718-5614) (1
) Column 6 of Detailed Description of the Invention in the Specification, Contents of Correction (1) (4) In the 4th line of page 8 of the specification, [Light ray to the movable lens group at] is changed to "Focus of the entire system at When the distance is normalized to 1, the paraxial ray is corrected as the axial ray to the movable lens group. In the 5th line, "respectively αP, α2" is changed to "respectively α2.α2゜Δ'Y−ΔY+ΔY (E) (
a) (■E)・-αpnp◆apIp (
C) (IIIE)・-α2■2◆Otsu nP (
d) (PE) m -αP pP(e) (VEI) m -Qp v, + ap mP(f)
(VE2) ”-ap P,
(g) (IIIE”)・ap”mp -2ap ap
UP+cx,"IP (h)(PE')・α,z
p , (i)(VE”l
)s ap”Vp −2a, a, Inp
+Qp”np (j) (VE”2)* (Ip”
Qp pp(k)(ΔE)−−2(α°2−αp)
(1) (ΔE')・-ap' (ap
Vp -ap (mp order Pp)) ◆2ap (Ep
((Xp mp −Qp np )−ap” (a
pIlp-apIp)
(m) (n E) gradient ap IF
(c') (mE) LgQp Ilp
(d') (PE) 4 0
(e') (VEI) # ap
mP(f')(VE2) Lr-Qp Pp
(g') (I[mE2) 4 ap2
Ip (h') (PE2) ~ 0
(i') (VE'l) "r Qp"
u p (J') (VE'2) 40
(k') (ΔE) ~ -2α+,
(1') (ΔE') # -QP'
I p (In')

Claims (1)

[Scope of Claims] (1) A fixed lens group that is immovable in a direction orthogonal to the optical axis in order from the object side and a movable lens group that corrects the pretension of a photographed image by moving in a direction orthogonal to the optical axis. It has two lens groups, the movable lens group is composed of at least one positive lens and at least one negative lens, and when the focal lengths of the fixed lens group and the entire system are F_1 and F_T, respectively, 4F_T<|F_1 | A photographic lens with an anti-vibration function that satisfies the following conditions. (2) Photographing with an image stabilization function according to claim 1, characterized in that the following condition is satisfied when the focal length of the movable lens group is F_2: 0.25F_T<F_2<0.8F_T lens. (3) Conditions such that 43<@ν@_P @ν@_N<40 when the average values of the Abbe numbers of the materials of the positive lens and negative lens in the movable lens group are @ν@_P and @ν@_N, respectively. A photographic lens having an anti-vibration function according to claim 1 or 2, which satisfies the following.