Image sensing apparatus and method of acquiring traveling characteristics of light-shielding member

An image sensing apparatus comprising:

• an image sensing element having a plurality of pixels that converts an optical image of an object incident thereon to an electrical image signal and outputs the image signal;
• a light-shielding member that is operable to occlude an aperture to said image sensing element;
• storage means;
• control means that is configured to acquire traveling characteristics of said light-shielding member based on an image signal output from a selected partial area of said image sensing element, store the acquired traveling characteristics in said storage means, and shift the selected partial area to another partial area placed at a different position spaced apart from the selected partial area along the traveling direction of said light-shielding member,
• wherein the traveling characteristics of the light-shielding member is acquired by said control means on the basis of image signals output from the selected partial area and the another partial area, and
• wherein said control unit, when acquiring and updating the traveling characteristics, is adapted to perform:
• a first reading control of reset scanning the image sensing element based on the traveling characteristics stored in said storage means, shielding said image sensing element by scanning said light-shielding member after a preset exposure period, and providing an image signal from the partial area,
• a second reading control, prior to the first reading control, of accumulating charge for the same length of time as the exposure period, and providing an image signal from the partial area,
• acquiring characteristic data showing the traveling characteristics based on the image signals output as a result of the first and second reading controls, and storing the acquired characteristic data in the storage means;
• and
• acquiring the traveling characteristics using the characteristic data stored in said storage means.

A method of estimating the traveling characteristic of the shutter blade(s) in a camera having an image sensing element including a plurality of rows of photoelectric pixels, said method comprising:

• measuring the charge accumulated in pixels in a first selected partial area of the image sensing element in a time period Tc,
• measuring the charge accumulated in pixels in a second selected partial area of the image sensing device in the time period Tc, the second selected partial area being spaced apart from the first selected partial area in the direction of travel of the shutter blade(s),
• resetting the pixels to restart charge accumulation,
• driving the shutter blade(s) to travel to stop the light from impinging upon the first and second selected partial areas of the image sensing element after a time period nominally equal to the time period Tc, but differing from Tc by different amounts because of the position/time traveling characteristic of the shutter blade(s),
• measuring the charge accumulated in the pixels in the first selected partial area of the image sensing element in the time period Ta, this time period starting with the pixel resetting operation on the first selected partial area and ending when the edge of the shutter blade(s) crosses the first selected partial area and blocks the light from impinging upon the first selected partial area,
• measuring the charge accumulated in the pixels in the second selected partial area of the image sensing element in the time period Tb, this time period starting with the pixel resetting operation on the second selected partial area and ending when the edge of the shutter blade(s) crosses the second selected partial area and blocks the light from impinging upon the second selected partial area,
• calculating from the accumulated charge measured during time periods Tc Ta and Tb the time when the edge of the shutter blade(s) cross the first and second selected partial areas, thereby providing an estimate of said traveling characteristic.