Focusing device for use in optical apparatuses
AssigneeMinolta Camera Kabushiki Kaisha
InventorsShinichi Mori, Keijiro Sakamoto, Hiroaki Nakauchi, Akiyoshi Hamada, Kazuyuki Yoshida
Life of this patent
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Abstract
A focusing device for use in micro film readers or the like for projecting micro images to give in-focus conditon exactly and readily. The present device includes a memory for storing a distance data representing the distance between an original and a projective lens at in-focus position thereof, and a sensor for measuring the distance between an original and the projective lens wherein the projective lens is moved to the in-focus position by a focusing motor in response to the distance data stored in the memory and a signal representing the measured distance generated from the sensor.
Claims21
A focusing device for use in an optical apparatus which projects an image of an original to a fixed projective surface with a projective lens, the device comprising:
- drive means for shifting the projective lens along the optical axis;
- measurement means, adapted to shift together with the projective lens, for measuring a distance between the original and the projective lens and for generating a distance signal representing the measured distance;
- memory means for storing distance data according to the distance signal generated from the measurement means when the projective lens is shifted to an in-focus position by a manual focusing operation;
- and
- control means for generating a drive signal to the drive means in order to shift the projective lens toward the in-focus position when a distance represented by the distance signal which is generated from the measurment means is different from a distance represented by the distance data which is stored in the memory means.
A focusing device for use in an optical apparatus which projects an image of an original to a fixed projective surface with a projective lens, the device comprising:
- drive means for shifting the projective lens along the optical axis;
- measurement means, adapted to shift together with the projective lens, for measuring a distance between the original and the projective lens and for generating a distance signal representing the measured distance;
- memory means being provided to the projective lens for storing a distance data representing a distance between the original and the projective lens in an in-focus position according to the charactereistic of the lens;
- and
- control means for controlling the drive means to shift the projective lens to the in-focus position in response to the distance data stored in the memory means and the distance signal generated from the measurement means.
A focusing device for use in an optical apparatus provided with a projective lens thereon comprising:
- drive means for shifting the projective lens along the optical axis;
- memory means for storing a distance data representing a distance between an original and the projective lens in an in-focus position;
- measurement means, adapted to move relatively to the movement of the projective lens, for measuring a distance between the original and the projective lens and for generating a distance signal representing the measured distance;
- and
- control means for controlling the drive mean in order to coincide a distance represented by the distance signal which is generated from said measurement means with a distance represented by the distance data which is stored in the memory means.
Dependencies are inferred from the claim text.