Lens apparatus

Abstract

A lens apparatus which can remove a backlash positively is provided. In the lens apparatus, a drive source is controlled so as to performing: moving a focus lens from a reference position toward one end of an optical lens stroke, and moving the focus lens toward the other end of the optical lens stroke. When the focus lens reaches the other end of the optical lens stroke, the drive source is controlled so as to perform moving the focus toward the reference position, and further, when a focus point position is determined to be between the reference position and the other end of the optical lens stroke as well as when it is detected that the focus lens reaches the reference position, the drive source is controlled so as to perform moving the focus lens from the reference position toward one end of the optical lens stroke by an amount to removal of a backlash, and moving the focus lens up to the focus point position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention will appear more fully upon consideration of the exemplary embodiment of the invention, which are schematically set forth in the drawings, in which:

FIG. 1 shows a lens apparatus of an exemplary embodiment according to the invention;

FIG. 2 shows an exemplary embodiment of a shading plate and a photo interrupter;

FIG. 3 is a flow chart of the operation (first embodiment) of the lens apparatus;

FIG. 4 shows the movement (first embodiment) of a focus lens;

FIG. 5 shows an example of an AF evaluation value;

FIG. 6 shows the movement (modification) of the focus lens;

FIG. 7 shows another example of the AF evaluation value;

FIG. 8 shows the movement (modification) of the focus lens;

FIG. 9 shows the movement (the point at issue) of the focus lens;

FIG. 10 shows an operation to measure or calculate the pulse numbers P1 and P2;

FIG. 11 shows an operation to measure or calculate the pulse numbers P1 and P2;

FIG. 12 shows a flow chart of the operation (second embodiment) of the lens apparatus;

FIG. 13 shows a flow chart of the operation (second embodiment) of the lens apparatus; and

FIG. 14 shows the movement (second embodiment) of the focus lens.

Claims

1. A lens apparatus comprising: a focus lens;a drive source generating a driving force to move the focus lens forward or backward within an optical lens stroke of the focus lens;a gear train transmitting the driving force to the focus lens; anda sensor detecting that the focus lens reaches a reference position in the optical lens stroke,whereinthe drive source is controlled so as to perform:a first step of moving the focus lens from the reference position to a first end of the optical lens stroke and moving the focus lens from the first end to a second end of the optical lens stroke, while AF evaluation values with respect to positions of the focus lens are obtained to determine a position, in the optical lens stroke, of the focus lens coming into focus; anda second step of moving the focus lens from the second end of the optical lens stoke toward the reference position, andwherein when the position of the focus lens coming into focus is determined to be between the reference position and the second end of the optical lens stroke and when the sensor detects that the focus lens reaches the reference position in the second step, the drive source is controlled so as to perform:a third step of moving the focus lens from the reference position toward the first end of the optical lens stroke by a distance to remove a backlash of the gear train; anda fourth step of moving the focus lens up to the position of the focus lens coming into focus.

2. The lens apparatus according to claim 1, wherein when the position of the focus lens coming into focus is determined to be between the reference position and the first end of the optical lens stroke and when the sensor detects that the focus lens reaches the reference position in the second step, the drive source is controlled so as to perform a step of moving the focus lens from the reference position to the position of the focus lens coming into focus.

3. A lens apparatus comprising: a focus lens;a drive source generating a driving force to move the focus lens forward or backward within an optical lens stroke of the focus lens;a gear train transmitting the driving force to the focus lens; anda sensor detecting that the focus lens reaches a reference position in the optical lens stroke,whereinthe drive source is controlled so as to perform:a first step of moving the focus lens from the reference position toward a first end of the optical lens stroke; anda second step of moving the focus lens toward the reference position at a timing after a position of the focus lens coming into focus is determined to be between the reference position and the first end of the optical lens stroke, andwherein when the sensor detects that the focus lens reaches the reference position in the second step, the drive source is controlled so as to perform:a third step of moving the focus lens from the reference position toward the second end of the optical lens stroke by a distance a distance to remove a backlash of the gear train; anda fourth step of moving the focus lens up to the position of the focus lens coming into focus.

4. A lens apparatus comprising: a focus lens;a drive source generating a driving force to move the focus lens forward or backward within an optical lens stroke of the focus lens;a gear train transmitting the driving force to the focus lens; anda sensor detecting that the focus lens reaches a reference position in the optical lens stroke,whereinthe drive source is controlled so as to perform a first step of moving the focus lens toward one of a first and second ends of the optical lens stroke, andwherein when the sensor detects that the focus lens reaches the reference position in the first step and when a first direction in which the focus lens is planned to move is determined, the drive source is controlled so as to perform:a step of moving the focus lens from the reference position in a second direction opposite to the first direction by a distance a distance to remove a backlash of the gear train; anda step of moving the focus lens in the first direction.

5. The lens apparatus according to claim 4, wherein the first step comprises: a step of moving the focus lens to one of a first and second ends of the optical lens stroke; and a step of moving the focus lens from the one of the first and second ends toward the reference position.