JP2592991B2 - Zoom lens barrel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel of a zoom lens having an optical type called an inner focus or a rear focus, which is one of focus adjustment mechanisms of a zoom lens.

[Conventional technology]

In recent years, various methods for adjusting the focus by moving a lens group other than the first group on the object side have been proposed in order to improve the performance and magnification of a zoom lens.

In addition, as a method that has been used for a long time, a mechanical stopper that changes the rotation angle of the focus ball according to the zoom position to change the closest shooting distance of the zoom lens by zooming, or a device that devises the shape of the closest end is practical. It has been transformed.

Also, in particular, the auto focus of the zoom lens has become common, and the demand for the light weight of the focus lens and the inner focus or the rear focus type zoom lens in which the movable portion cannot be directly touched from the outside is increasing. , 3
With a zoom lens of about 4 ×, even if it is restricted at the wide-angle end at a close distance from the telephoto end, it does not cause a great obstacle, and the same close-up distance is often required over the entire zoom range.

[Problems to be solved by the invention]

However, in the above conventional example, it is difficult to satisfy the optical performance at a short distance on the telephoto side with a high-magnification zoom lens. There is no choice but to get close to the shooting distance determined by.

When considering the auto focus, if there is a mechanical switch that restricts the closest distance of the focus by its rotation angle depending on the zoom area, manually switch the zoom to change the mechanical switch mechanism. When this happened, an overcurrent flowed through the focus drive motor and required special consideration.

[Means for solving the problem]

The present invention changes the abutting position between a focus cam and a focus cam follower in conjunction with a zooming operation to change a feeding amount for focusing of a lens used for focus adjustment. It is characterized by a zoom lens barrel set so that the displacement can be focused closer to the wide side than to the tele side.

〔Example〕

1 to 10 show an embodiment of the present invention, and FIG. 1 is a sectional view showing a tele end state of a lens. FIG. 2 is a sectional view showing a wide end state of the lens. FIG. 3 is a development view of the cam cylinder. FIG. 4 is a development view of the fixed cylinder. Fifth
The drawing is a developed view of the fitting portion of the fifth lens barrel. FIG. 6 is a development view of the first lens barrel. FIG. 7 is a development view of the hood cam cylinder. FIG. 8 is a development view of the focus connecting cylinder. FIG. 9 is a movement diagram of zooming during zooming of each zoom group. FIG. 10 is a detailed view around the focus cam.

1 to 9, I denotes a group I lens, II denotes a second group lens, III denotes a third group lens, IV denotes a fourth group lens, V denotes a fifth group lens, and VI denotes a sixth group lens. (Note that the portion indicated by A in FIG. 1 is a filter at a place where it can be detached.) In the figure, reference numeral 1 denotes a fixed cylinder, 1a denotes an outer straight groove, 1b denotes an inner straight groove, and 1c denotes a second group holding hole. Three are provided equally each. The outer diameter portion 1h has a peripheral hole 1i. Reference numeral 2 denotes a mount, which is fixed to the fixed cylinder 1 with screws 2a.
It holds the back cover 3 and has a detachable stopper pin 2b. The fixed cylinder 1 has an outer peripheral portion 1e, and the large-diameter portion 1e
Has a distance window 4 and an inner surface of the outer peripheral portion 1e has a step 1f and a fitting portion 1g. The rotary tube 5 is rotatably held at the step 1f and the fitting portion 1g. ing. A pin 5a is screwed into the front end of the rotary cylinder 5 from the outer periphery at two opposing positions, and has three protrusions 5b toward the inner periphery at the rear end. A focus unit 6 has a unit body 6a fixed to the fixed cylinder 1 by screws 6b.

6c is a known ultrasonic motor. 6d is an output member. 6e is a roller member and a shaft screw 6f on the outer periphery of the roller ring 6g
And is rotatably held at three equal positions. The roller ring 6g has an inner diameter fitted to the unit body 6a and is rotatably held, and a distance scale 6i is provided on an outer peripheral portion. 6h is an intermediate member, which is the unit body 6a.
The fitting is held and the outer peripheral part has three fitting vertical parts
6j, the fitting vertical groove 6j fits with the protrusion 5b on the inner peripheral portion at the rear end of the rotary cylinder 5, and can rotate integrally with the rotary cylinder 5. Reference numeral 6k denotes a pressing member of the ultrasonic motor 6c, and the ultrasonic motor 6c in the unit body 6a.
c, the output member 6d, the roller member 6e, and the intermediate member 6h are simultaneously and sequentially pressed. Reference numeral 7 denotes a focus key, which is fixed to a roller ring 6g in the focus unit 6 by a screw 7a. The key 7 has a fitting vertical groove 7b (not shown).

Reference numeral 8 denotes a focus connecting cylinder which is fitted to the inner surface of the fixed cylinder 1. Further, the inner peripheral surface has a vertical groove 8b. The pin 8a is screwed into the outer peripheral surface of the focus connecting cylinder 8. The pin 8a is thrust-restricted by the peripheral hole 1i of the small diameter portion 1h of the fixed cylinder 1. Further, a fitting vertical groove (not shown) of the key 7 is provided. The rotation is regulated by 7b (hereinafter referred to as key).

Reference numeral 9 denotes a first lens barrel which holds the first lens I,
At the fitting portion 9a on the inner surface of the rear end, the fixed cylinder 1
At the same time, a straight key 9b is screwed on the inner surface of the rear end.
It is fixed by 9c. The straight key 9b is fitted to the outer surface straight groove 1a of the fixed cylinder 1 so as to be held in the fixed cylinder 1 so as to be able to move straight. Further, the first lens barrel 9 has three cam grooves 9d equally in the front half thereof. In addition, the hood cam barrel 10 is fitted and held in the outer peripheral fitting part, and the thrust regulation of the hood cam barrel 10 is also realized, and the hood cam barrel 10 is attached to the first group lens barrel 9. It is held so that it can rotate freely at a fixed position.

Reference numeral 9e denotes a dowel provided on the front outer peripheral portion of the first-group barrel 9, which is provided at three equally spaced positions. Reference numeral 9f denotes a collar portion extending to the outer peripheral side of the first lens barrel 9, and has a fitting portion 9g on the outer peripheral portion. The hood cam cylinder 10 has a straight groove 10a and a cam groove 10a.
Are provided evenly in three at a time.

Reference numeral 11 denotes an operation ring, which has a fitting receiving portion 11a at an intermediate portion of the inner surface, and the fitting receiving portion 11a is fitted to a fitting portion 9g provided on a collar portion 9f extending to the outer peripheral side of the first lens barrel 9. By performing the combination and thrust control, the operation ring 11 can simultaneously perform the operation of the forward and backward movement to the first lens barrel 9. Also, the operation ring
The inner surface of 11 is provided with two internal vertical grooves 11b opposed to each other, and the internal vertical grooves 11b are fitted to the front end of the rotary cylinder 5 with the pins 5a screwed into the opposite two locations from the outer periphery. Thus, the rotation operation of the operation ring 11 can be constantly and stably transmitted to the rotary cylinder 5 and the intermediate member 6h in the focus unit 6.

Reference numeral 12 denotes a filter frame.
There is a filter screw 12a for screwing the fitting, and a fitting portion 12b is provided on the inner peripheral portion of the rear end. The fitting portion 12b is provided with three dowels 12c on the inside at equal places. In addition, longitudinal grooves 12d are provided on the inner surface of the intermediate portion at three equal positions. The flute 1
Reference numeral 2d fits with a dowel 9e provided on the front outer peripheral portion of the first-group barrel 9, and its rotation is restricted. Further, the fitting portion 12b of the rear end inner peripheral portion of the filter frame 12 is fitted to the outer periphery of the hood cam cylinder 10, and at the same time, the fitting portion 12b of the rear end inner peripheral portion of the filter frame 1 is inwardly fitted. Dowels 12c provided in three equal places
However, since it is engaged with the cam groove 10a provided in the hood cam cylinder 10, when the hood cam cylinder 10 eventually rotates,
First-group lens I in which filter frame 12 is held in first-group barrel 9
Is made straight forward.

Reference numeral 13 denotes a cam cylinder having a substantially large-diameter portion 13a and a small-diameter portion 13b, and the large-diameter portion 13a is fitted and held on the inner diameter of the fixed cylinder 1.
As shown in FIG. 3, the large diameter portion 13a is provided with three fixed pin cams 13c, three group cams 13d, four group cams 13e, and five group cams 13f, each of which is equally divided into three. The small diameter portion 13b is provided with a focus cam 13g. The outer peripheral portion of the front end has a fitting portion 13h having a larger diameter at one step, and fitting pins 13i are equally threaded into three places on the outer surface of the fitting portion 13h.

The fitting pin 13i penetrates the cam groove 9d of the first lens barrel 9 and simultaneously engages with the straight groove 10a of the hood cam cylinder 10. Therefore, the amount of rotation of the cam cylinder 13 regulates the amount of rotation of the hood cam cylinder 10, and the amount of feed of the filter frame 12 is determined according to the above description.

Reference numeral 14 denotes a second-group lens barrel which holds the second-group lens, and has a fitting portion 14a on the outer periphery thereof. The fitting portion 14a is provided with three fixed pins 14b equally. The fixing pin 14b provided on the fitting portion 14a is engaged with the fixing pin cam 13c provided on the large-diameter portion 13a of the cam cylinder 13 and simultaneously with the second group holding hole 1c provided on the fixed cylinder 1. Is engaged. Therefore, the two lens barrels 14 are fixed to the fixed barrel 1. The cam barrel 13 is provided with a fixed pin cam 13c provided on the large diameter portion 13a and the first group barrel 9
The rotational position and the thrust position are determined by the two position elements of the shape of the cam groove 9d provided in the first half of
The reference numeral 13 performs a rotational feeding operation by performing the forward / backward movement of the operation ring 11. Reference numeral 13j denotes a movable stop, which is fixed to the front end face of the cam cylinder 13.

Reference numeral 15 denotes a fifth-group lens barrel which holds the fifth-group lens and has a fitting portion.
15a, and the cam cylinder 13 is fitted and held in the large diameter portion 13a. Further, as shown in FIG. 5, a fifth group pin 15b is screwed into the fitting portion 15a of the fifth group barrel 15, and three third groove 15c and four fourth groove 15d are equally divided into three each. Is provided. A fifth group pin 15b screwed into the fitting portion 15a of the fifth group lens barrel 15 is fitted to a fifth group cam 13f provided in the large diameter portion 13a of the cam cylinder 13 and to an inner surface straight groove 1b of the fixed cylinder 1. Since the cam cylinder 13 is engaged at the same time, a predetermined zooming movement can be performed in a straight line by the above-described rotation feeding operation of the cam cylinder 13.

 Reference numeral 16 denotes a known electromagnetic diaphragm unit.

Reference numeral 17 denotes a third lens barrel, which holds a third lens group III and an electromagnetic diaphragm unit 16.

The third lens barrel 17 is fitted to and held by the fifth lens barrel 15, and a third group pin 17a screwed into the fitting surface is connected to the fifth lens barrel 15.
The third group groove 15c provided in the fitting portion 15a of the cam cylinder 13
Is engaged simultaneously with the third group cam 13d provided in the large-diameter portion, so that a predetermined zooming movement can be performed in a straight line by rotating and feeding the cam cylinder 13.

Reference numeral 18 denotes a fourth group cylinder which holds a fourth group lens IV. 5
The fourth group pin 18a screwed into the fitting surface is fitted and held in the group lens barrel 15, and the fourth group groove 15d and the cam cylinder 13 provided in the fitting part 15a of the fifth group lens barrel 15 are large. Since it is simultaneously engaged with the fourth group cam 13e provided on the radial portion, a predetermined zooming movement can be performed in a straight line by rotating and feeding the cam cylinder 13 similarly to the third group barrel 17.

Reference numeral 19 denotes a sixth-group lens barrel which holds the sixth-group lens VI, is fitted and held on the inner surface of the small-diameter portion 13b of the cam barrel 13, and
The sixth group pin 19a screwed into the fitting portion of the group lens barrel 19 is positioned by engaging the focus cam 13g of the cam barrel 6 and the vertical groove 8b on the inner peripheral surface of the focus connecting cylinder 8.

In FIG. 9, the zoom parameter is set to P at the wide end.
= 0 and P = 1 at the telephoto end.

The first unit I is substantially linearly extended, but when the zoom movement amount Z ₁ (P) of the first unit I is represented by a function of P, Z ₁ (P) = − 87.7291 × P −5.9751 × P ² +38.227 × P ³ −18.8765 × P ⁴ −7.2885 × P ⁵ + 6.64197 × P ⁶ (Equation 1)

 The second group is a fixed group.

 The third group is extended non-linearly.

 The fourth group is also extended nonlinearly.

 The fifth group is also extended nonlinearly.

The sixth group is also extended non-linearly. Further, in the present embodiment, since the sixth group VI also serves as a focus operation,
When the zoom movement amount in the infinite shooting state is represented by a function Z ₆ (P) of P similarly to the zoom movement amount Z ₁ (P) of the first unit I, Z ₆ (P) = − 52.2729 × P + 23. 3911 × P ² + 39.3588 × P ³ −236.458 × P ⁴ + 530.4948 × P ⁵ −580.5656 × P ⁶ + 292.4738 × P ⁷ −56.326298 × P ⁸ (Equation 2)

Also, when the amount of extension at the time of focusing of the sixth group VI is represented by DX (P) when the above-described Z ₆ (P) is considered as a reference position for each photographing object, extension of each distance from infinity is considered. The quantities are expressed as follows:

FIG. 10 is a detailed view of a state of the wide end of the focus cam 13g provided at the small diameter portion 13b of the cam cylinder 13 and a tele end of the focus cam 13g, and the surroundings of the focus connecting cylinder 8 relating thereto. An arrow A indicates a process in which the focus connecting cylinder 8 shifts from an infinite focus state to a state close to the focus. Arrow B indicates the transition from the wide end to the tele end of the previous zoom, and the arrow B has the same shape as the fixed pin cam 13c provided on the large diameter portion 13a of the cam cylinder 13.

The length of the drawing Z ₆ is a zoom movement amount at infinite states of the sixth group VI.

 In the figure, θ is the rotation angle of the focus from infinity.

In the drawing, FX (wide, θ) is the focus moving amount at the wide end at F (θ).

In the figure, FX (tele, θ) is the focus movement amount at the tele end at F (θ).

As is apparent from the figure, the focus movement amount FX increases as the zoom approaches the telephoto end.

In the drawing, a cam shape A represents a conventional cam shape, which is before correction according to the present invention.

Note that point A in the figure is the origin when representing the cam shape.

[Explanation of focus cam shape]

In FIG. 10, point A corresponds to the infinite focus position at the wide end, and this is the origin. Consider a parameter P that is positive from the point A to the right in the figure.
= 1 is set to the abscissa at the infinite position at the telephoto end.

Also, a positive value is given from the origin A in the direction in which light passes (downward in the figure). When the ordinate of the cam is DF _(P) , DF (P) = − 0.61387832 × P−1.0218228 × P ² −1.1237228 × P ³ −2.7742780 × P ⁴ −1.3559715 × P ⁵ + 3.8409674 × P ⁶ −4.4016533 × P ⁷ −2.9247311 × P ⁸ + 3.0573613 × P ⁹ (Equation 13)

The cam shape A before correction is DF (P) = -0.587895 x P -1.083093 x P ² -1.627202 x P ³ -1.503167 x P ⁴ -0.043344 x P ⁵ -0.994588 x P ⁶ -2.833623 x P ⁷ +0.000983 x P ⁸ −1.354200 × P ⁹ (Equation 13 ′).

[Explanation of zoom operation]

Next, in the above-described configuration, when the operation ring 11 is pulled out from the wide end to the tele end for the zooming operation, the first lens barrel 9 moves straight by the same amount as described above, and at the same time, the cam cylinder 13 performs the rotation feeding. . For this reason, the filter frame 12 advances straight forward with respect to the first lens barrel 9. The fifth group lens barrel 15 moves straight forward by the rotation of the cam barrel 13, and at the same time, the third group lens barrel 17 and the fourth group lens barrel 18 also move straight. On the other hand, since the sixth lens barrel 19 is restricted in rotation by the vertical groove 8b of the focus connecting cylinder 8 which is connected to the Fukasky when the focus is fixed as described above, it moves straight.

[Explanation of focus operation]

The focus rotation angle θ has a negative value in the present embodiment. (This will be referred to as a telestrate cam.) The amount of extension at the focus rotation angle θ at the zoom amount P is the cam coordinate DE (P + θ) at (P + θ).
What is necessary is just to find out how much has changed from the cam coordinate DF (P) in (P). Therefore, assuming that the feeding amount is DF (P, θ), DF (P, θ) = DF (P + θ) −DF (P) (Expression 14)

Here, for example, at P = 1, that is, at the telephoto end, the amount of extraction ▲ DX ^xm ₍₁₎ at a certain shooting distance (probably xm ₎
If ▼ and DF (1, θ) become the same, it means that the lens is in focus at the telephoto end, and the zooming is changed from P = 1 to P = 0 without changing θ (in other words, fixing the focus). When changing, the amount of cam deviation It is represented by

The cam shape A before correction in FIG. 10 is such that ΔDX (P) always becomes 0 (between P = 0 to P = 1).
In the present embodiment, as in the case of the focus cam 13g in the figure, when the movement amount of the focus group is increased in the wide side of zooming and in the region where the focus rotation angle is increased, the closest shooting distance is significantly increased here. It can be used up to the short distance side.

Table 1 shows each zoom parameter and focus rotation angle θ.
Shows the value of the shooting distance at.

In the vicinity of the wide end of the zoom parameter P = 0, since the movement amount of the focus lens group can be set to be larger than the focal length on the telephoto side, the shooting distance extends to a position that is much closer. Note that the cam shape A before the correction represents the conventional shape before the present embodiment, which is designed so that the focus movement amount is reduced even at the wide-angle side at the telephoto shooting distance.

[Effects of the Invention] As described above, the present invention also provides a zoom lens barrel having a sufficiently close shooting distance on the wide side without using mechanical switching, even in a high-magnification zoom lens barrel. Can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a tele end state of an interchangeable lens embodying the present invention. FIG. 2 is a sectional view showing a wide end state of the interchangeable lens embodying the present invention. FIG. 3 is a development view of a cam barrel of an interchangeable lens embodying the present invention. FIG. 4 is a development view of a fixed barrel of the interchangeable lens embodying the present invention. FIG. 5 is a developed view of a fifth lens barrel of the interchangeable lens embodying the present invention. FIG. 6 is a development view of the first lens unit barrel of the interchangeable lens embodying the present invention. FIG. 7 is a developed view of a cam cylinder for a hood of an interchangeable lens embodying the present invention. FIG. 8 is a development view of a focus connecting cylinder of the interchangeable lens embodying the present invention. FIG. 9 is a zoom movement diagram of each zoom group of the interchangeable lens embodying the present invention. FIG. 10 is a detailed view around a focus cam of an interchangeable lens embodying the present invention. 1 ... fixed cylinder, 5 ... rotating cylinder, 7 ... key, 8 ... focus connecting cylinder, 9 ... group 1 lens barrel, 10 ... hood cam cylinder, 11 ... operating ring, 13 ... cam Cylinder, 13d ... 3 group cam, 1
3e 4 group cam, 13f 5 group cam, 13g Focus cam, 14 2 group barrel, 15 5 group barrel, 17 3 group barrel, 18 4 group barrel , 19 ... 6th lens barrel, point M ...
The origin of the cam, the arrow A ... the closest focus rotation direction, θ ...
… Focus rotation angle, FX… Focus extension amount, Z6…
… Focus group zoom movement amount, cam shape L …… Conventional cam shape

Claims (1)

(57) [Claims] 1. A zoom lens barrel having an optical system in which an amount of extension for focusing of a first lens acting on a focus changes in accordance with a change in focal length due to zooming, moving in an optical axis direction. A first cam follower that moves the first lens in the optical axis direction; a cam member that contacts the first cam follower, rotates around the optical axis by a focusing operation; and is interlocked with the zooming operation. An interlocking mechanism that rotates the cam member about an optical axis, changes a contact position between the cam and the cam follower, and changes a feeding amount for focusing the first lens. Wherein the cam displacement of the cam is set such that the focusable distance on the wide side is closer to the focusable distance on the telephoto side than the focusable distance on the telephoto side. Murens barrel.