Photographing device and control method of rotational angle position of polarized light filter

A method of controlling a rotational-angle position of a polarizing filter, wherein the polarizing filter rotates about an optical axis of a photographing optical system, provided with an image sensor, and is positioned in an optical path of the photographing optical system, the method comprising:

• preliminarily rotating the polarizing filter at a predetermined cycle pattern;
• detecting an object luminance signal, of object-emanating light which transmits through the polarizing filter and is captured by the image sensor, when the polarizing filter preliminarily rotates at the predetermined cycle pattern;
• generating a rotation control signal by eliminating any frequency component of a cycle pattern that is different from the predetermined cycle pattern from the detected object luminance signal;
• and
• controlling a rotational angle position of the polarizing filter based on the generated rotation control signal,
• wherein the rotation control signal is generated by eliminating, from the detected object luminance signal, any frequency component having a cycle or phase that differs from a cycle or phase of a luminance signal corresponding to a polarized state when the polarizing filter is rotated preliminarily at the predetermined cycle pattern.

A photographing device comprising:

• a photographing optical system provided with an image sensor;
• a polarizing filter that rotates about an optical axis of said photographing optical system and is positioned in an optical path of said photographing optical system;
• a rotation driver that preliminarily rotates said polarizing filter at a predetermined cycle pattern;
• a detector that detects an object luminance signal of object-emanating light transmitting through said polarizing filter and captured by said image sensor when said rotation driver preliminarily rotates said polarizing filter at said predetermined cycle pattern;
• a signal generator that generates a rotation control signal by eliminating any frequency component of cycle pattern that is different from said predetermined cycle pattern from said object luminance signal detected by said detector;
• and
• a controller that controls a rotational angle position of said polarizing filter based on said rotation control signal generated by said signal generator,
• wherein said rotation driver rotates said polarizing filter at an inconstant velocity, and
• wherein said rotation driver rotates said polarizing filter at said inconstant velocity by rotating said polarizing filter by 90 degrees at a first rotational speed, and thereafter rotating said polarizing filter by a further 90 degrees at a second rotational speed that is a double speed of said first rotational speed.

A method of controlling a rotational-angle position of a polarizing filter, wherein the polarizing filter rotates about an optical axis of a photographing optical system, provided with an image sensor, and is positioned in an optical path of the photographing optical system, the method comprising:

• preliminarily rotating the polarizing filter at a predetermined cycle pattern;
• detecting an object luminance signal, of object-emanating light which transmits through the polarizing filter and is captured by the image sensor, when the polarizing filter preliminarily rotates at the predetermined cycle pattern;
• generating a rotation control signal by eliminating any frequency component of a cycle pattern that is different from the predetermined cycle pattern from the object luminance signal;
• and
• controlling a rotational angle position of the polarizing filter based on the generated rotation control signal,
• wherein the polarizing filter is rotated at an inconstant velocity during the preliminarily rotating of the polarizing filter, and
• wherein, during the preliminarily rotating of the polarizing filter at the inconstant velocity, the polarizing filter rotates by 90 degrees at a first rotational speed and thereafter rotates by a further 90 degrees at a second rotational speed that is a double speed of the first rotational speed.