JP2003035857A - Zoom lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens barrel capable of accelerating and downsizing a focus drive while securing lens holding accuracy. SOLUTION: This zoom lens barrel 1 is equipped with a zoom mechanism for integrally moving at least two lens components 11, 12 or 13 out of a plurality of lens components moving in an optical axis direction in order to change a focal distance, and a focus lens moving mechanism for moving either focus lens component 12 with respect to the other 11 or 13 out of at least two lens components. The focus lens moving mechanism is constituted of a barrel 29 and guides 32 and 33 freely rotated around an optical axis and integrated in an optical axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel.

[0002]

2. Description of the Related Art Conventionally, there are several methods of focusing a zoom lens barrel as follows.

The first is zoom focus. That is, the cam groove for driving the lens is formed in a step shape so that the zoom area and the focus area are alternately continuous, and the focus can be driven at a predetermined focal length. In this method, since the entire lens barrel is driven, the driving time becomes long and the release time lag becomes large. Also, since many parts are moved, errors due to backlash and distortion tend to increase. If a large amount of run-up is driven to stabilize this, the driving time becomes longer.

Secondly, it is a lens frame driving type. That is, the lens frames holding the lens groups of the respective components are entirely moved to perform zoom drive, and in a specific lens frame, only the lens groups held in the lens frame are partially moved to perform focus drive. I do. This type is easy to drive at high speed. However, with respect to the lens group for focusing, since a double holding and driving mechanism is required for focusing and zooming, the configuration is complicated, downsizing is difficult, the cost is high, and the lens holding accuracy is secured. Difficult to do.

The third type is a feed screw type. That is, the feed screw is screwed into the lens frame holding the lens group, and the lens group is moved in the axial direction by the rotation of the feed screw. In this type, in order to prevent the inclination of the lens frame, it is necessary to provide a guide shaft or lengthen the fitting portion with the guide shaft.
It is difficult to achieve downsizing while ensuring lens holding accuracy.

[0006]

SUMMARY OF THE INVENTION Therefore, a technical problem to be solved by the present invention is to provide a zoom lens barrel capable of achieving high-speed focus driving and miniaturization while ensuring lens holding accuracy. Is.

[0007]

In order to solve the above technical problems, the present invention provides a zoom lens barrel having the following configuration.

The zoom lens barrel includes a zoom mechanism and a focus lens moving mechanism. The zoom mechanism is
At least two of the plurality of lens components are moved integrally. The focus lens moving mechanism moves one focus lens component of the at least two lens components with respect to the other. The focus lens moving mechanism is composed of a cylinder and a guide that are rotatable around the optical axis and are integrated in the optical axis direction.

In the above structure, the plurality of lens components are appropriately moved in the optical axis direction to change the focal length. The zoom drive mechanism moves the plurality of lens components in the optical axis direction, but at least two of the plurality of lens components are used.
The two are moved integrally, that is, in the same direction and by the same distance. Therefore, the relative distance between the at least two lens components does not change. On the other hand, by driving the focus lens moving mechanism, it is possible to change the relative distance between the at least two lens components and adjust the focus position.

According to the above arrangement, only the focus lens component is driven during focusing, and the focus driving can be speeded up. By configuring the focus lens moving mechanism by the cylinder and the guide, the focus lens component is held with a length of about the diameter of the cylinder, so it is possible to reduce the size while maintaining the inclination with respect to the optical axis with high accuracy. .

Preferably, during zooming, both the zoom mechanism and the focus lens moving mechanism are driven.
At the time of focusing, only the focus lens moving mechanism is driven.

According to the above arrangement, by moving the focus lens component in advance during zooming, it is possible to make the distance for moving the focus lens component during focusing as short as possible. As a result, the release time lag can be shortened and the focus drive can be sped up.

Preferably, the zoom mechanism integrally moves the focus lens component and the lens components arranged before and after the focus lens component. The focus lens moving mechanism includes a guide that extends in parallel with the optical axis between lens components arranged before and after the focus lens component and guides the focus lens component in the optical axis direction.

With the above arrangement, when the focus lens component moves in the optical axis direction by the tube and the guide of the focus drive mechanism, the guide is restricted so that the displacement of the focus lens component in the direction perpendicular to the optical axis is prevented. Therefore, it is possible to move the focus lens component while maintaining the focus lens component with high accuracy.

Preferably, the focus lens moving mechanism is a helicoid mechanism.

In this case, for example, the lens frame holding the focus lens component and the cylinder are configured to be helicoidally coupled. The use of the helicoid mechanism makes it possible to increase the number of engaging portions, which is excellent in strength and inclination accuracy. It is also easy to shield the focus lens component from the outer shape side.

Preferably, the focus lens moving mechanism is a cam mechanism.

In this case, for example, the cam pins provided on the lens frame holding the focus lens component engage with the cam grooves provided on the cylinder and the guide, respectively, and the relative rotation of the cylinder and the guide causes the focus lens component to drive the cam. To be done. By using a cam mechanism, you can realize non-linear feed,
It is possible to drive the focus lens component with different resolution depending on the focal length.

Preferably, a relative position detecting means for detecting a relative position of the focus lens component with respect to the other (that is, the other) lens component is provided.

According to the above arrangement, when the focus lens component is moved with respect to the other lens component that is integrally moved by the zoom mechanism, the relative position of the focus lens component with respect to the other lens component is It can be detected by the relative position detecting means. By using this detection data, the focus lens component can be appropriately moved with respect to the other lens component during zoom driving, and the focus lens component can be moved according to an arbitrary zoom curve or focus extension. Therefore, the degree of freedom in zoom drive and focus drive is increased.

Preferably, a photoreflector arranged in a lens frame holding the focus lens component and a reflection pattern arranged on one of the cylinder and the guide so as to face the photoreflector are provided. With the movement of the focus lens component, the photo reflector moves along the reflection pattern.

According to the above arrangement, the photo reflector moves along the reflection pattern, so that the relative position of the focus lens component by the focus lens moving mechanism can be detected. Further, since it is non-contact, it does not cause a disturbance to the driving of the lens component and can be driven and detected with high accuracy.

Preferably, a focus motor and an output unit which is rotated by the focus motor and engages with one of the cylinder and the guide are arranged in the lens frame holding the focus lens component. By rotating the output unit, the one cylinder can be rotated with respect to the other cylinder.

According to the above construction, the focus motor is rotated so that the barrel and the guide are relatively rotated, whereby the focus lens component can be driven. Since the focus motor moves together with the lens frame holding the focus lens component, the structure of the driving force transmission system can be simplified. Further, if the focus lens component is arranged at a position where the optical path is narrowed, the focus motor can be arranged in a space that is free in the radial direction, and the zoom lens barrel can be downsized.

[0025]

DETAILED DESCRIPTION OF THE INVENTION A zoom lens barrel 10 according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a front end side sectional view of the zoom lens at a long focal length, FIG. 2 is a rear end side sectional view, and FIG. 3 is a short focal length sectional view.

As shown in FIGS. 1 to 3, in the fixed barrel 22 of the zoom lens barrel 10, a drive ring 24 and a rectilinear helicoid barrel 25, a rotary barrel 26 and a rectilinear barrel 27, and a forward barrel 28.
And the helicoid ring 29 are arranged, and the long gear 20 rotates to integrally move in the axial direction.
The first lens group 11, the second lens group 12, and the third lens group 13 are adapted to move in the optical axis direction.

The drive ring 24 is disposed inside the fixed barrel 22, and its rear end engages with a helicoid formed on the inner peripheral surface of the fixed barrel 22. The drive ring 24 meshes with the long gear 20 and, when rotated by the long gear 20, moves in the axial direction by a helicoid.

The long gear 20 is driven by a zoom motor 40 via a reduction system 42, as schematically shown in FIG. While detecting the rotation amount of the zoom motor 40 by the photo interrupter 41, the zoom lens barrel 10
Control the expansion and contraction of.

The straight advancing helicoid cylinder 25 is arranged inside the drive ring 24, and the rear end portion of the straight advancing helicoid cylinder 25 is engaged with the straight advancing groove provided in the fixed cylinder 22 so that the rotation thereof is restricted. Therefore, the drive ring 24 is engaged with the drive ring 24 such that the drive ring 24 is relatively rotatable and cannot move in the axial direction.

The rear end of the rotary cylinder 26 is engaged with a helicoid formed on the inner peripheral surface of the straight advancing helicoid cylinder 25.
The pin engages with the drive ring 24 so as to be movable in the axial direction and rotates together with the drive ring 24.

A straight advancing cylinder 27 is arranged inside the rotating cylinder 26, and is relatively rotatable and cannot relatively move in the axial direction.
It is adapted to engage with the rotary cylinder 26. Straight barrel 27
Has its rear end engaged with a straight-moving groove formed in the straight-moving helicoid cylinder 25 to restrict rotation.

The forward end of the forward cylinder 28 is adapted to engage with a helicoid formed on the inner peripheral surface of the rotary cylinder 26. The first group lens frame 11a holding the first lens group 11 is fixed to the front end side of the forward movement barrel 28, and the third group lens frame 13a holding the third lens group 13 is fixed to the rear end side. . A rectilinear groove 13b is formed in the third group lens frame 13a so that the front end side of the rectilinear cylinder 27 is engaged. As a result, rotation of the forward cylinder 28 is restricted.

Inside the advancing cylinder 28, a helicoid ring 29 is disposed between the first group lens frame 11a and the third group lens frame 13a so as to be relatively rotatable and relatively immovable in the axial direction. . As shown in the development view of FIG. 7, a helicoid 29b is formed on the inner peripheral surface of the helicoid ring 29 on the front end side. A part of the helicoid 29b is extended to the rear end side to form a gear portion 29a which is cut in a valley shape in the axis O direction so as to mesh with an output gear 18 which will be described later. A reflection pattern 30 is attached along the helicoid 29b so as to face a photo reflector 17 described later. A plurality of bright and dark patterns 30a and 30b that repeat at a predetermined pitch are arranged in the middle of the reflection pattern 30, and patterns 30c and 30d having a long pitch are provided at both ends.
Are arranged.

Inside the helicoid ring 29, a second lens group frame 14 for holding the second lens group 12 which is a focus lens component is arranged. In the second group lens frame 14, a focus motor 16, a photo reflector 17 and the like are arranged radially outside the second lens group 12, and a shutter unit 15 is arranged rearward. Since the optical path is narrowed in the second lens group 12, it is possible to effectively utilize the empty space outside the second lens group 12 to dispose the focus motor 16, the photo reflector 17, etc., and to reduce the size of the zoom lens barrel 10. You can

On the outer peripheral surface of the second group lens frame 14, the helicoid 1
4a is formed, and the helicoid 29b of the helicoid ring 29 is formed.
To engage with. The space between the second group lens frame 14 and the helicoid ring 29 is shielded by the helicoid. That is, the second group lens frame 14 and the helicoid ring 2
Between 9 and 9, helicoids are arranged so as to overlap each other when viewed from the optical axis direction, and light cannot pass through the helicoids.

As schematically shown in FIG. 1, the rotation of the focus motor 16 is transmitted to the helicoid ring 29 via the reduction gear system 19, whereby the second lens group frame 14 moves in the helicoid ring 29. It is supposed to do. The rotation of the focus motor 16 is detected by the photo interrupter 35.

As shown in the sectional view of FIG. 4 and the front view of FIG. 5, the deceleration system 19 controls the rotation of the focus motor 16.
It is a gear train that is transmitted to the output gear 18 and the pulse gear 34 that are output units. The photo interrupter 35 is arranged so as to face the pulse gear 34, and can detect the rotation of the focus motor 16 with high resolution. The output gear 18 meshes with the gear portion 29a of the helicoid ring 29.

As shown in FIG. 5, the second group lens frame 14 is formed with a pair of through holes 14a and 14b, and the first group lens frame 11a is formed.
Pair of guide shafts 3 fixed between the second lens group frame 13a and the third lens group frame 13a
2, 33 are inserted so that the second group lens frame 14 is guided in the optical axis direction while being prevented from rotating. One through hole 1
4a is circular, the entire circumference of the guide shaft 32 is in sliding contact, the other through hole 14b is oval, the guide shaft 33 is in sliding contact only in the circumferential direction, and a gap is formed in the radial direction. Frame 1
The rotation of the No. 4 guide shaft 32 is restricted. By engaging the second group lens frame 14 with the guide shafts 32 and 33, the position in the direction perpendicular to the optical axis and the rotation with respect to the optical axis are restricted.

A wall 1 is formed around the through holes 14a and 14b.
4r, 14s, and 14t are erected. Wall 14r,
A flocked cloth (not shown) is fixed to the inner peripheral surfaces of 14s and 14t, the guide shafts 32 and 33 are surrounded by a flocked cloth, and light is shielded between the through holes 14a and 14b and the guide shafts 32 and 33. It is like this.

Next, the operation will be described.

By rotating the zoom motor 40, the long gear 2
0, the drive ring 24, and the rotary cylinder 26 rotate, and the zoom lens barrel 10 expands and contracts. As a result, the first, second, and third lens groups 11, 12, 1 supported via the advancing barrel 28 are provided.
3 moves.

When the focus motor 16 rotates, the output gear 18 and the helicoid ring 29 rotate, and the second group lens frame 14 moves with respect to the helicoid ring 29. By detecting the reflection pattern 30 with the photo reflector 17, the position of the second group lens frame 14 with respect to the helicoid ring 29 can be detected.

During zoom driving, the zoom motor 40 is rotated to move the first, second and third lens groups 11, 12, 13 in the optical axis direction.

At this time, the focus motor 16 is driven in association with the rotation of the zoom motor 40, and the second group lens 1
2 may be moved to an appropriate position with respect to the first and third lens groups 11 and 13. As a result, the first, second, and third lens groups 11, 12, and 13 can be moved according to an arbitrary zoom curve, and the degree of freedom in zoom driving is expanded.

During focus driving, only the focus motor 16 is driven. The position of the second group lens frame 14 is based on the reflection pattern detected by the photo reflector 17 described above.
Focus motor 1 detected by photo interrupter 35
The position of the second lens group frame 14, that is, the second lens group 12 can be finely adjusted by the rotation of 6. Since only the second group lens frame 14 is driven during focus drive, the focus drive can be sped up and the release time lag can be shortened.

As described above, the zoom lens barrel 1
With 0, the focus driving speed can be increased and the size can be reduced while ensuring the lens holding accuracy.

The present invention is not limited to the above embodiment, but can be implemented in various other modes.

For example, instead of driving the second group lens frame 14 by a helicoid mechanism, a cam pin provided on the lens frame (for example, a member of reference numeral 14) is a cylinder (for example, 28 (or 29)).
Member) and a guide (for example, a member of reference numeral 29 (or 28)) may be engaged with each other so that the lens frame is cam-driven by relative rotation of the cylinder and the guide. By using a cam mechanism, you can realize non-linear feed,
It is possible to drive with different resolution depending on the focal length.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a zoom lens barrel according to an embodiment of the present invention. The front end side at the start of operation is shown.

FIG. 2 is a rear end side sectional view of the zoom lens barrel of FIG.

3 is a cross-sectional view of the zoom lens barrel of FIG. 1 when retracted.

FIG. 4 is a sectional view of a main part of a second group lens frame.

FIG. 5 is a front view of a second group lens frame.

FIG. 6 is a perspective view of a second group lens frame.

FIG. 7 is a development view of a helicoid ring.

[Explanation of symbols]

11 1st lens group (other lens component) 12 2nd lens group (focus lens component) 13 3rd lens group (other lens component) 14 2 group lens frame 14a helicoid 16 focus motor 17 photoreflector (relative position detection means) ) 18 output gear (output section) 20 long gear (zoom mechanism) 22 fixed cylinder (zoom mechanism) 24 drive ring (zoom mechanism) 25 straight advancing helicoid cylinder (zoom mechanism) 26 rotating cylinder (zoom mechanism) 27 straight advancing cylinder (zoom mechanism) ) 28 forward cylinder (zoom mechanism) 29 helicoid ring (focus lens moving mechanism, cylinder) 30 reflection pattern (relative position detecting means) 32, 33 guide shaft (focus lens moving mechanism, guide)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 7/04 E

Claims (5)

[Claims] 1. At least two of the plurality of lens components
And a focus lens moving mechanism that moves one focus lens component of the at least two lens components with respect to the other of the at least two lens components. A zoom lens barrel, characterized in that the zoom lens barrel is composed of a barrel and a guide that are rotatable and integrated in the optical axis direction. 2. The zoom lens barrel according to claim 1, wherein both the zoom mechanism and the focus lens moving mechanism are driven during zooming, and only the focus lens moving mechanism is driven during focusing. 3. The zoom mechanism integrally moves the focus lens component and lens components arranged before and after the focus lens component, and the focus lens moving mechanism comprises lenses arranged before and after the focus lens component. 3. The zoom lens barrel according to claim 1, further comprising a guide extending between the components in parallel with the optical axis to guide the focus lens component in the optical axis direction. 4. A focus reflector provided with a photoreflector arranged in a lens frame holding the focus lens component, and a reflection pattern arranged opposite to the photoreflector on one of the cylinder and the guide. 4. The zoom lens barrel according to claim 1, 2 or 3, wherein the photo reflector moves along the reflection pattern as the component moves. 5. A lens frame holding the focus lens component is provided with a focus motor and an output section which is rotated by the focus motor and engages with one of the cylinder and the guide. The output section is rotated by the rotation of the output section. The zoom lens barrel according to claim 1, wherein the one cylinder is rotatable with respect to the other cylinder.