This application is based upon and claims priority of Japanese Patent Application No. 11-136808 filed May 18, 1999, the contents being incorporated herein by reference.
The present invention relates to a lens barrel and more specifically to a lens barrel having a changeover member for changing over between automatic focusing and manual focusing.
Conventionally, a lens of a single lens reflex camera is known which has a changeover member, such as an AF-MF changeover ring, which changes focusing between automatic focusing and manual focusing.
The above-mentioned single lens reflex camera lens (hereafter called an AF-MF changeover lens) has a manual focusing unit, such as a manual operating portion, which makes the AF-MF changeover lens work as a manual focusing lens. The AF-MF changeover lens also has an autofocus unit, such as an automatic focusing driving unit, which makes the AF-MF changeover lens work as an autofocus lens. The AF-MF changeover lens further includes a clutch mechanism which is located between a lens unit in a lens barrel and the manual operating portion as mentioned above, or between the lens unit in the lens barrel and the automatic focusing driving unit as mentioned above.
This clutch mechanism is driven by operating the above-mentioned changeover member (the AF-MF changeover ring). By operating the AF-MF changeover ring, the clutch selectively connects the lens unit with either of the manual operating portion or the automatic focusing driving unit, according to the selected position of the AF-MF changeover ring. Then, either the manual focusing unit or the autofocus unit selectively becomes operable.
Accordingly, when the changeover member (the AF-MF changeover ring) and the clutch mechanism select the autofocus unit, the autofocus driving unit can drive the lens unit, leaving the manual operating portion free.
Furthermore, when the changeover member and accordingly the clutch mechanism select the manual focusing unit, the manual operating portion can move the lens unit with no load of the autofocus driving unit being applied, because the manual focusing ring being disconnected with the autofocus driving unit, thereby focusing adjustment by the manual operating portion being made smoothly.
In the case where a user frequently changes focusing manners between an AF shooting (automatic focusing shooting) and an MF shooting (manual focusing shooting) by using the changeover member (the AF-MF changeover ring), it is preferable to improve an operability of the changeover member by making an operating force of the changeover member small or an operation of the changeover member simple.
However, in the case where a user exclusively performs AF shooting, it is preferable that the changeover member (the AF-MF changeover ring) is held at the automatic focusing position so that the changeover operation from the automatic focusing position to a manual focusing position is hard to be made. On the contrary, in the case where a user exclusively performs MF shooting, it is preferable that the changeover member (the AF-MF changeover ring) is held at the manual focusing position and the changeover operation from the manual focusing position to the automatic focusing position is hard to be made.
Accordingly, for a user who doesn""t frequently change the shooting manners between the AF shooting and the MF shooting, if the changeover force of the changeover member is small, or if the changeover operation of the changeover member is simple, this causes a problem of an inconvenient operability of the changeover member.
Furthermore, there is another problem that the changeover member is apt to move from an original position when a camera is not used (for example, when a camera is being carried in a bag). This problem leads to a need to lock the changeover member not to move from the original position even for a user who frequently changes the shooting manners between the AF shooting and the MF shooting.
Meanwhile, if design is so made that the changeover is hard to be made in consideration of or on behalf of the user who doesn""t frequently change the shooting manners between AF shooting and MF shooting, in other words, if the changeover is possible only by using a large operation force or complex operation, this causes another problem that the operability of the changeover member is deteriorated for the user who frequently changes the shooting manners between AF shooting and MF shooting.
It is an object of the present invention to overcome the above-described problems of the conventional lens barrel.
It is another object of the present invention to provide a lens barrel having a changeover unit for changing over between autofocus shooting and manual shooting, in which the lens barrel is capable of selectively choosing either a manual focusing unit or an automatic focusing unit by a manual operation and in which the operability of the lens barrel is diversified according to the versatility of shooting manners between AF shooting and MF shooting, thereby improving convenience of the lens barrel.
In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a lens barrel which comprises a manual focusing unit for manually adjusting the focusing operation of a lens, an automatic focusing unit for automatically adjusting the focusing operation of the lens, and a changeover unit for selectively choosing either the manual focusing unit or the automatic focusing unit, and a locking mechanism for prohibiting the changeover operation of the changeover unit.
The changeover unit may be so composed to singly changeover between the manual focusing unit and the automatic focusing unit and the locking mechanism may be independent from the changeover unit.
Furthermore, in accordance with another aspect of the present invention, the manual focusing unit may include a manual operating member for manually moving a lens unit of the lens barrel; the automatic focusing unit may include an autofocus driving unit for automatically moving the lens unit; the changeover unit may include a clutch mechanism for selectively connecting the lens unit to either the manual operating portion or the autofocus driving unit, and include a changeover member which is rotatably fitted to a fixed barrel of the lens barrel and makes the clutch mechanism connect the lens unit selectively to either the manual operating portion or the autofocus driving unit according to the rotation of the changeover member; and the locking mechanism may prohibit the changeover member from rotating, thereby prohibiting the changeover operation of the changeover unit.
Furthermore, in accordance with another aspect of the present invention, the locking mechanism may include an operating button movably mounted on the changeover member, a locking element which interlocks with the operating button, and at least one locking recess formed on the fixed barrel, whereby when the changeover member is rotated by a predetermined angle while the operating button is being pressed, the locking element engages with the locking recess and prohibits the rotation of the changeover member.
Furthermore, in accordance with another aspect of the present invention, the lens barrel may further include a clicking mechanism for clicking the changeover member at a position where the changeover member chooses the manual focusing unit or the automatic focusing unit.