Image pickup device, method of controlling image pickup device, and recording medium
View Patent ↗An image pickup device is provided which includes: an auto focus control unit sampling contrast values as a function of a relative distance from an object by detecting a contrast of an image of the object while driving a lens in an optical axis direction, calculating a focused focal position on the basis of the contrast values, and driving the lens to the focused focal position; a shake detecting unit detecting at least an amount of shake in the optical axis direction of the lens; and a selection judging unit judging selection and non-selection of the sampled contrast values depending on the amount of shake in the optical axis direction of the lens at the time of the sampling. Here, the auto focus control unit calculates the focused focal position on the basis of the contrast value judged as being selected by the selection judging unit among the sampled contrast values.
1. An image pickup device comprising:
an auto focus control unit sampling contrast values of an image of an object while driving a lens in an optical axis direction, calculating a focused focal position based on the contrast values, and driving the lens to the focused focal position;
a shake detecting unit detecting an amount of shake in the optical axis direction; and
a selection judging unit selecting ones of the sampled contrast values based on the amount of shake detected at the time of sampling,
wherein the auto focus control unit calculates the focused focal position based on the selected ones of the sampled contrast values,
wherein the selection judging unit:
selects one of the sampled contrast values when the amount of shake detected at the time of sampling the one of the sampled contrast values is less than or equal to a first reference amount of shake,
discards the one of the sampled contrast values when the amount of shake detected at the time of sampling the one of the sampled contrast values is greater than or equal to a second reference amount of shake that is larger than the first reference amount of shake, and
selects the one of the sampled contrast values when the amount of shake detected at the time of sampling the one of the sampled contrast values is greater than the first reference amount of shake and less than the second reference amount of shake, and assigns the one of the sampled contrast values to a selected one of:
a lens position at the time of sampling the one of the sampled contrast values,
a lens position at the time of sampling a sample contrast value immediately prior to the one of the sampled contrast values, and
a lens position at the time of sampling a sample contrast value immediately subsequent to the one of the sampled contrast values,
wherein the selection judging unit generates a corrected lens position by correcting the lens position at the time of sampling the one of the sampled contrast values based on the amount of shake, and selects the selected one of the lens positions to minimize a difference between the selected one of the lens positions and the corrected lens position.
2. The image pickup device according to claim 1 , wherein the shake detecting unit includes gyro sensors and detects the amount of shake on the basis of an angular velocity detection signal output from the corresponding gyro sensor.
3. The image pickup device according to claim 1 , wherein the auto focus control unit includes an auto focus correcting unit performing a correction control so as to correct the focused focal position on the basis of the amount of shake in the optical axis direction of the lens and to drive the lens to the corrected focused focal position.
4. The image pickup device according to claim 3 , wherein the auto focus control unit deviates a relative position of the lens to an image pickup element by the amount of shake by means of the correction control.
5. The image pickup device according to claim 3 , further comprising a shutter switch operating a shutter,
wherein the auto focus control unit drives the lens to the focused focal position and holds the lens at the corresponding position at the time of semi-shuttering the shutter switch, and
wherein the auto focus correcting unit performs the correction control at the time of full-shuttering the shutter switch.