JP2007264156A - Lens position detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens position detecting device capable of easily suppressing the plastic deformation of a metal brush or the positioning to an adjusting reference position, regarding the lens position detecting device configured to detect a positional relation between the metal brush and a pattern electrode as an electric signal. <P>SOLUTION: The lens position detecting device is configured to detect the positional relation between the metal brush and the pattern electrode as the electric signal by making the metal brush rub the pattern electrode fixedly wound in a peripheral direction around the outer periphery of a fixed cylinder. A rotating force transmission member includes a projecting part facing a direction opposite to the fixed cylinder, and a distance between the projecting part and the fixed cylinder is set so that the plastic deformation of the metal brush may not occur when being pressed against the fixed cylinder in the case of deforming the rotating force transmission member toward the fixed cylinder, and with the engagement of the projecting part with a projection receiving part provided on the surface of the fixed cylinder, the rotation around the optical axis is restricted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens position detection device, and more particularly to a zoom position detection device in a lens barrel such as a camera.

Conventionally, various methods have been proposed for a driving structure of an optical lens holding barrel for focus / zoom and the like.
Among them, in order to improve optical performance and operability, an increasing number of products are equipped with an encoder for detecting the position of the lens holding barrel.
By detecting the position of the lens holding barrel, the control constants for controlling the drive mechanism are changed, and appropriate and high-speed lens driving is realized. In particular, the autofocus performance of an interchangeable lens attached to an autofocus camera It contributes to the improvement.
Various methods of such an encoder have been proposed, and the following methods are known as methods that are generally used.
That is, there is a combination of a conductive brush and an electric wiring board that has an encode pattern member that slides with the brush, and the pattern state that abuts is switched depending on the relative position of the brush and the encode pattern member.

With the recent demand for miniaturization and high performance, the arrangement method of the above encoders has also changed, but various improvements have been made so that the encoder can be realized in as little space as possible.
For example, Patent Document 1 discloses an encoder configured as shown in FIG. 6 as an encoder for detecting a zoom position in a lens barrel.
In FIG. 6, a zoom key 14 which is a connecting part for integrally rotating the cam cylinder 2 and the zoom ring 16 around the optical axis is provided.
Zoom flex having an encoding pattern contact (not shown) is affixed to the outer periphery of the guide tube 1 that is diameter-fitted on the outer peripheral side of the cam tube 2. The zoom brush 19 is disposed at a position corresponding to the encode pattern contact and is fixed to the zoom key 14.
That is, the rotational positions of the zoom ring 16 and the cam cylinder 2 around the optical axis are detected by energization signals due to the zoom flex and the sliding of the zoom brush 19.
In general, the zoom brush 19 is secured to the zoom key 14 at a position extending in the optical axis direction as shown in FIG.
JP-A-8-240762 (FIG. 3)

However, the conventional example has the following problems. In the above conventional example, when a metal brush is attached to the focus key and fixed with a screw or the like, it is indispensable to screw a screw or other tool toward the center of the optical axis against the screw. is there.
In that case, the pressing force causes the focus key to be elastically deformed from the mounting portion with the manual ring, and the metal brush attached to the elastically deformed focus key is pressed against the outer periphery of the fixed cylinder and exceeds the elastic deformation region. This may cause plastic deformation.
For this reason, there is a problem that a desired encoding output cannot be obtained because the encoding pattern surface cannot be contacted in use.

Further, in order to match the relationship between the electrical wiring board having the encoding pattern attached to the fixed cylinder and the brush and the angular phase relation between the focus key and the focus lens holding barrel to a desired positional relation, the following positions are used. Adjustment is required.
That is, when the position adjustment for moving the metal brush on the focus key in the direction of rotation is performed, a reference adjustment position is required. In order to specify the reference adjustment position, the conventional method requires the rotation. There was only the rotation end position of the transmission key. Therefore, it is difficult to perform reference adjustment positioning at an arbitrary position during rotation.
In particular, in a focus lens mechanism having an inner focus mechanism, the reference position of the cam is the reference point of the cam use point for positioning the focus lens, and the reference distance is in the middle of the entire rotation angle of the focus key. Often there is a state.
Therefore, it is important to improve the performance of the lens barrel that adjustment positioning at an arbitrary rotational position is possible.

In view of the above problems, the present invention can suppress plastic deformation of a metal brush in a lens position detection device having a configuration in which a metal brush is slid on a pattern electrode and the positional relationship is detected as an electrical signal. An object of the present invention is to provide a lens position detection device.
It is another object of the present invention to provide a lens position detection device that can easily position the metal brush to the adjustment reference position in the lens position detection device.

In order to achieve the above object, the present invention provides a lens position detection device configured as follows.
The lens position detection device of the present invention includes a fixed cylinder that holds a lens holding member, a rotational force transmission member that is disposed on the outer peripheral side of the fixed cylinder and transmits rotational force to the lens holding member, and the rotational force transmission member With a metal brush attached to be positionably adjustable,
A lens position detection device comprising a configuration in which the metal brush is slid on a pattern electrode wound and fixed in the circumferential direction around the outer periphery of the fixed cylinder, and a positional relationship between the metal brush and the pattern electrode is detected as an electric signal. In
The rotational force transmission member has a protrusion directed in a direction facing the fixed cylinder,
An interval between the protrusion and the fixed cylinder is set to an interval at which the metal brush is pressed against the fixed cylinder and does not cause plastic deformation when the rotational force transmitting member is deformed to the fixed cylinder side. It is characterized by that.
Further, in the lens position detection device of the present invention, the fixed cylinder has a protrusion receiving portion provided on the surface of the fixed cylinder that engages with the protrusion of the rotational force transmitting member,
When the distance between the protrusion and the fixed cylinder deforms the rotational force transmitting member toward the fixed cylinder, the protrusion of the rotational force transmitting member and a protrusion receiving portion provided on the surface of the fixed cylinder Are engaged, and the rotation around the optical axis is restricted.
In the lens position detection device of the present invention, the protrusion is provided at a position away from the fixing portion of the rotational force transmission member and the mounting portion of the metal brush in the optical axis direction. .
In the lens position detection device of the present invention, the protrusion is semicircular.
In the lens position detection device of the present invention, the protrusion receiving portion is formed by a protrusion having a V-shaped groove.
In the lens position detecting device of the present invention, the rotational force transmitting member is provided with a fixed position in the rotational direction at a position in an optically infinite state.
In the lens position detection apparatus of the present invention, the lens holding unit is a lens holding barrel that holds an optical system that moves in the optical axis direction to change a focal length or a subject distance.
In the lens position detection device of the present invention, the rotational force transmitting member is a focus key.
In the lens position detection device of the present invention, the fixed tube is a fixed tube of an interchangeable lens.

According to the present invention, it is possible to suppress plastic deformation of the metal brush in the lens position detection device having a configuration in which the metal brush is slid on the pattern electrode and the positional relationship is detected as an electrical signal.
Further, according to the present invention, the lens position detection device can easily position the metal brush to the adjustment reference position.

Embodiments of the present invention will be described below.
With the above configuration, the object of the present invention can be achieved. In the present embodiment, specifically, the lens position detection device is applied to a lens barrel and configured as follows. Can do.
An optical system that changes the focal length or subject distance by moving the lens barrel in the optical axis direction, a lens holding barrel that holds the optical system, a fixed barrel that holds the entire lens barrel, and the fixed barrel It is set as the structure provided with the 2nd fixed cylinder arrange | positioned from the fixed cylinder fixed to the outer peripheral side.
A rotation operation ring fitted to the second fixed inner periphery and supported to be rotatable around the optical axis; and a rotation transmission member fixed to the rotation operation ring and transmitting a rotational force to the lens holding barrel. Provided.
Further, the metal brush is supported by the rotation transmission member so that the position of the brush can be adjusted, and a pattern electrode is wound around and fixed to the outer periphery of the fixed cylinder in the circumferential direction. The amount of movement of the optical system is determined by the metal brush and the pattern electrode. It is comprised so that it may detect as an electric signal by the relationship.
At this time, a projection is provided on the inner peripheral surface of the foka ski toward the outer periphery of the fixed cylinder, and the protrusion has a desired gap with respect to the outer periphery of the fixed cylinder in a normal use state.
On the other hand, when the focus key is elastically deformed toward the inner peripheral side of the lens when the metal brush is attached, the attached metal brush has a sufficient protruding amount so as not to be deformed by plastic deformation.
In addition, a protrusion receiving portion is formed on the outer periphery of the fixed cylinder so as to face the protrusion, and when the transmission member is pressed from the outer peripheral side of the lens barrel, the transmission member is deformed, and the protrusion has a specific angular phase. And the protrusion receiving portion are engaged to restrict the rotation around the optical axis.

  According to the above configuration, since the protrusion is disposed on the inner peripheral surface of the focus key toward the outer peripheral surface of the fixed cylinder, the metal brush is deformed when the metal brush is attached and when the position of the metal brush is adjusted. And the like can be easily positioned at the adjustment reference position.

Examples of the present invention will be described below, but the present invention is not limited to the configurations of these examples.
In this embodiment, an interchangeable lens barrel attached to a single-lens reflex camera or the like in this embodiment to which the present invention is applied will be described.
FIG. 1 is a cross-sectional view taken along a plane including the optical axis of the interchangeable lens barrel in the present embodiment.
In addition, in the said figure which shows a present Example, only the structure required for description is represented, The other structure is abbreviate | omitted as not shown in figure.
FIG. 2 is a front view of the lens barrel of FIG. 1 as viewed from the mount side, and FIGS. 3 and 4 are perspective views for explaining a part of the configuration of the lens barrel.

In FIG. 1, reference numeral 1 denotes a lens mount for attachment to a camera, and reference numeral 2 denotes a fixed cylinder for fixing the lens mount integrally.
Reference numeral 3 denotes a second fixed cylinder that is positioned and fixed to the fixed cylinder. Reference numeral 4 denotes a manual ring which is fitted to the inner periphery 3a of the second fixed cylinder and is bayonet-coupled by the peripheral groove portion 3b and the outer peripheral projection 4a and is supported rotatably around the optical axis.
Reference numeral 5 denotes a focus key, and a 5a portion is fixed to the 4b portion of the manual ring 4 with a screw or the like, and extends into a space between the outer periphery of the fixed cylinder 2 and the inner periphery of the second fixed cylinder 3, The manual ring 4 and the manual ring 4 are supported so as to be rotatable about the optical axis.
Reference numeral 6 denotes a focus lens, which can adjust the focal position of the interchangeable lens barrel by moving in the optical axis direction.
Reference numeral 7 denotes a focus lens holding barrel. The focus lens 6 is held on the inner periphery thereof, and the cam followers of the cam mechanisms 2a and 7a provided on the inner periphery of the fixed tube 2 are cam-engaged, thereby rotating around the optical axis. It is supported so that it can advance and retreat in the direction of the optical axis while rotating.
Reference numeral 7b denotes a guide groove extending in the optical axis direction. The guide groove 7b engages with the 5b portion of the focus key 5 described above, and can rotate integrally around the optical axis and can move relatively in the optical axis direction. ing.

Reference numeral 8 denotes a conductive metal brush. The 8a surface abuts on the 5c surface of the focus key 5 and is fixed by screws. A portion 5d is a guide portion of the metal brush 8 on the focus key 5, and restricts movement of the metal brush in the optical axis direction.
Reference numeral 9 denotes a flexible wiring board having an encode pattern in the rotation direction about the optical axis, and is positioned and affixed to the outer peripheral surface 2 a of the fixed cylinder 2.
The tip 8b of the metal brush 8 is brought into pressure contact with the encode pattern 9a by its spring force, and the conduction combination of a plurality of signal lines on the encode pattern is switched by relative rotation around the optical axis.
The signal line conduction information, that is, the position information of the focus lens in the optical axis direction is transmitted to a control board (not shown).

In order to fix the metal brush 8 to the focus key 5 with mounting screws or the like, tool holes provided in the 4c portion of the manual ring 4 and the 3c portion of the second fixed cylinder 3 are used.
That is, the metal brush 8 is inserted through these tool holes while the metal brush tip 8b is pressed against the surface of the encode pattern 9a, and fixed to the surface of the focus key 5c with screws.
A protrusion 5 e is integrally provided on the inner peripheral surface of the focus key 5.
The position of the projection 5e in the optical axis direction is provided at a position excluding the encode pattern 9a, but it is desirable that the position be as far as possible from the focus key attachment position 5a and the outer peripheral surface of the fixed cylinder be present on the inner peripheral side.
Further, in a normal use state, the protrusion 5e does not come into contact with the outer peripheral surface of the fixed cylinder, and the height of the protrusion 5e is fixed so as to allow bending to elastically deform the tip 8b of the metal brush 8. It is set to be larger than the gap interval between the outer peripheral surface of the cylinder and the inner periphery of the focus key.

During the process of assembling the lens barrel of this embodiment, the metal brush is attached last. When the tool holes 3c and 4c provided in the second fixed cylinder and the manual ring are overlapped, the focus key 5 and the encode pattern portion 9a can be seen from the outside of the interchangeable lens barrel.
The metal brush is inserted through the tool hole, and is fixed to the brush mounting surface 5c of the focus key 5 with screws while elastically deforming the portion 8b.
At that time, conventionally, the focus key is deformed by the pressing force of the screw tightening tool, the distance between the metal brush tip 8b and the encode pattern 9a is narrowed, and the metal brush 8 is plasticized beyond the elastic deformation region. There was a risk of deformation. However, in this embodiment, the protrusion 5e and the outer peripheral surface of the fixed cylinder are in contact with each other before receiving the force, so that the metal brush does not undergo plastic deformation beyond the elastic deformation region. ing.
Further, after the metal brush is screwed, the normal positional relationship is restored, so that no problem is caused in operation.

Next, a description will be given of the configuration of the present embodiment that enables easy positioning to the adjustment reference position of the metal brush when the position of the metal brush is adjusted.
FIG. 5 is a diagram for explaining a state in which the focus key protrusion and the V-shaped protrusion having a V-groove shape on the outer periphery of the fixed cylinder are in contact with each other when the focus key is elastically deformed toward the outer periphery of the fixed cylinder. An enlarged view is shown.
In FIG. 5, reference numeral 2c denotes a V-shaped protrusion having a V-groove shape provided integrally on the outer periphery of the fixed cylinder.

In this embodiment, a V-shaped projection 2c having a V-groove shape is integrally provided on the outer periphery of the fixed cylinder, and becomes the reference position of the mechanical component when the rotation phase is the same as that of the projection 5e of the focus key.
When the focus key is elastically deformed toward the outer periphery of the fixed cylinder, the projection 5e of the focus key and the V-shaped protrusion 2c on the outer periphery of the fixed cylinder come into contact with each other to determine the position.
In a normal use state, the focus key protrusion 5e and the V-shaped protrusion 2c on the outer periphery of the fixed cylinder have a gap in the radial direction and do not come into contact with each other.
The focus brush is elastically deformed toward the outer periphery of the fixed cylinder, and the metal brush on the focus key is moved along the guide 5d while the focus key protrusion 5e and the V-shaped protrusion 2c on the outer periphery of the fixed cylinder are engaged. The corresponding reference position of the encode pattern is adjusted.
This eliminates problems such as a drop in the accuracy of lens control caused by errors in the position of the flexible wiring board pasted on the outer periphery of the fixed cylinder, and corrects the correspondence between the mechanism part and the electrical signal part. Can be performed.
That is, in the prior art, the reference position of the mechanical parts such as the focus key with respect to the fixed cylinder and the electric signal reference position obtained by the positional relationship between the encoding pattern and the metal brush with respect to the fixed cylinder are often misaligned. Can be eliminated.
The shapes of the focus key protrusion 5e and the V-shaped protrusion 2c on the outer periphery of the fixed cylinder are not limited to the shapes of the present embodiment, and are uniquely rotated when the focus key is pressed against the outer periphery of the fixed cylinder. What is necessary is just to be able to determine the positional relationship.

Sectional drawing cut | disconnected by the plane containing the optical axis which shows the structure of the interchangeable lens barrel in the Example of this invention. The front view which looked at the lens-barrel of FIG. 1 which shows the structure of the Example of this invention from the mount side. The perspective view which took out some structures of the lens-barrel in the Example of this invention. The perspective view which took out the structure of a part of this lens barrel in the Example of this invention. To explain a state in which the focus key protrusion and the V-shaped protrusion having a V-groove shape on the outer periphery of the fixed cylinder are in contact with each other when the focus key in the embodiment of the present invention is elastically deformed toward the outer periphery of the fixed cylinder. FIG. Sectional drawing of the zoom lens barrel for demonstrating the structural example of the encoder of the zoom position detection in the lens barrel of patent document 1 which is a prior art example.

Explanation of symbols

1: Lens mount 2: Fixed cylinder 2a: Focus cam 2b: Outer peripheral surface 2c: V-shaped protrusion on the outer periphery of the fixed cylinder 3: Second fixed cylinder 3a: Inner peripheral fitting surface 3b: Peripheral groove 3c: Tool hole 4: Manual Ring 4a: Peripheral protrusion 4b: Focus key mounting surface 4c: Tool hole 5: Focus key 5a: Mounting surface 5b: Guide portion 5c: Brush mounting surface 5d: Brush guide portion 5e: Focus key protrusion 6: Focus lens 7: Focus lens holding barrel 7a: Cam follower 7b: Guide groove 8: Metal brush 8a: Mounting surface 8b: Brush tip 9: Flexible wiring board 9a: Encoding pattern

Claims (9)

A fixed cylinder that holds the lens holding member, a rotational force transmitting member that is disposed on the outer peripheral side of the fixed cylinder and transmits a rotational force to the lens holding member, and a metal that is attached to the rotational force transmitting member so that the position can be adjusted. With a brush,
A lens position detection device comprising a configuration in which the metal brush is slid on a pattern electrode wound and fixed in the circumferential direction around the outer periphery of the fixed cylinder, and a positional relationship between the metal brush and the pattern electrode is detected as an electric signal. In
The rotational force transmission member has a protrusion directed in a direction facing the fixed cylinder,
An interval between the protrusion and the fixed cylinder is set to an interval at which the metal brush is pressed against the fixed cylinder and does not cause plastic deformation when the rotational force transmitting member is deformed to the fixed cylinder side. A lens position detecting device characterized by the above. The fixed cylinder has a protrusion receiving portion provided on a surface of the fixed cylinder that engages with a protrusion of the rotational force transmitting member,
When the distance between the protrusion and the fixed cylinder deforms the rotational force transmitting member toward the fixed cylinder, the protrusion of the rotational force transmitting member and a protrusion receiving portion provided on the surface of the fixed cylinder The lens position detecting device according to claim 1, wherein the lens position is engaged and the rotation around the optical axis is restricted.   3. The lens according to claim 1, wherein the protrusion is provided at a position further away from the fixing portion of the rotational force transmission member and the mounting portion of the metal brush in the optical axis direction. Position detection device.   The lens position detection device according to claim 1, wherein the protrusion has a semicircular shape.   5. The lens position detection device according to claim 1, wherein the protrusion receiving portion includes a protrusion having a V-shaped groove.   6. The lens position detection device according to claim 1, wherein the rotational force transmitting member is provided at a position where the rotational direction is fixed in an optically infinite state.   7. The lens holding barrel according to claim 1, wherein the lens holding unit is a lens holding barrel that holds an optical system that moves in an optical axis direction to change a focal length or a subject distance. 8. Lens position detection device.   The lens position detection device according to claim 1, wherein the rotational force transmission member is a focus key.   The lens position detection device according to claim 1, wherein the fixed cylinder is a fixed cylinder of an interchangeable lens.

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