Elmo Company, Limited

Masaaki Toguchi

Yasuhiro Kondo

Tetsuya Horike

An imaging device moves a zoom lens, so as to change the magnification of an image of a subject, and obtains a near limit position of a focusing lens to the subject at a zoom lens position. When a target position of the focusing lens, which is required to keep the image in focus after the zoom lens is moved, is located on a near side, i.e., on an imaging plane side, of a threshold position determined based on the obtained near limit position, focus control is performed to move the focusing lens and thereby focus. When the target position of the focusing lens is not located on the near side but is located on a subject side of the threshold position, on the other hand, focus control is performed to move the zoom lens to a wider position and subsequently move the focusing lens to focus the image.

Imaging device and control method thereof

A camera system includes a camera, a shooting field shifting mechanism, a shift amount acquiring unit, and a masking processor that masks a masking target within a captured image flame. The masking processor includes first and second position computing units, and mask area establishing unit. The first and second position computing units compute, based on the shift settings of the shooting field shifting mechanism, first and second relative positions of the masking target relative to the shooting field. The mask area establishing unit establishes a mask area to mask the masking target on the captured image flame, based on the first and second relative positions.

Camera system with masking processor

A hill-climbing scheme of an automatic focusing process performed in a digital video camera obtains a moving speed Vj and an AGC gain Gj of a compensator lens every time an AF evaluation value AFj is detected corresponding to the position of the compensator lens. Adjustment factors &#x3b1; and &#x3b2; are computed with the moving speed Vj and the AGC gain Gj as parameters, where 0&#x3c;&#x3b1;&#x3c;1 and 0&#x3c;&#x3b2;&#x3c;1. The adjustment factor &#x3b1; is set to increase with an increase of the moving speed Vj, while the adjustment factor &#x3b2; is set to increase with a decrease of the AGC gain Gj. The automatic focusing process determines an in-focus position, based on the result of comparison between each detected AF evaluation value AFj and a threshold value TH. The threshold value TH is computed by multiplying a maximum value AFmax of the AF evaluation value AFj detected in the course of the hill-climbing scheme by the computed adjustment factors &#x3b1; and &#x3b2;. This arrangement attains the effective focusing technique of adequately determining the in-focus position according to various imaging conditions.

Imaging device and focusing method

In a digital video camera according to one aspect of the invention, a black level of a video signal is specified during an initialization process. An autofocusing process obtains an AF evaluation value and a brightness evaluation value at each current position of a compensator lens and updates a maximum AF evaluation value and a corresponding position of the compensator lens based on the obtained data. The autofocusing process also detects an AGC gain, computes an offset value of the AF evaluation value from the detected AGC gain, the obtained brightness evaluation value, and the specified black level, and calculates a threshold value from the computed offset value and the updated maximum AF evaluation value. When the obtained AF evaluation value is less than the calculated threshold value, the lens position corresponding to the maximum AF evaluation value is specified as the focus position. When the obtained AF evaluation value is not less than the calculated threshold value, on the other hand, this series of processing is repeated with a position shift of the compensator lens by a preset number of steps. This arrangement ensures efficient and precise hill-climbing autofocus control in view of the potential influence of high frequency noise in the digital video camera or another electronic camera.

Imaging device and autofocusing method

A video camera constructed according to one aspect of the focus adjustment device moves a focus lens forward and backward and detects peak values of an AF evaluation value of the focus lens in the forward moving direction and in the backward moving direction. The video camera calculates a correction value based on a difference between the peak value of the evaluation value detected in the forward motion of the lens and the peak value of the evaluation value detected in the backward motion of the lens. The video camera corrects the AF evaluation value with the calculated correction value and detects a focused position of the lens based on the corrected AF evaluation value in moving the lens.

Focus adjustment device, imaging device and focus adjustment method

In an imaging device according to one aspect of the invention, an amplitude demand Ac is specified according to a wobbling amplitude Ai required for detection of a hill-climbing direction based on an F value and a wobbling amplitude Ag required for detection of the hill-climbing direction based on an AGC gain. An allowable amplitude Am set for preventing a potential image shake caused by a magnification change with a position shift of a compensator lens in wobbling is specified corresponding to a zoom position and an object distance. When Ac&#x3e;Am, the control procedure restricts the wobbling amplitude to Am and increases a sampling number of AF evaluation values to be detected at respective positions in wobbling, in order to ensure the sufficient detection performance of the hill-climbing direction. When Ac&#x25a1;Am on the other hand, the control procedure sets Ac to the wobbling amplitude. This arrangement of the imaging device efficiently ensures the sufficient detection performance of the hill-climbing direction for autofocusing control, while effectively preventing deterioration of the quality of a captured image due to the magnification change in the wobbling motion.

In response to the user's short press of one preset button, a video camera according to one aspect of the invention reads out preset values stored in an EEPROM and adjusts the pan position, the tilt position, the position of a zoom lens, the position of a focus lens based on the read-out preset values. A movable range of the focus lens is restricted to a specific limited range between a closer direction end and a background position as a previously focused position. Hill-climbing control is then performed in this restricted movable range. This arrangement effectively ensures quick adjustment of the focus position of the video camera.

Imaging device and focus adjustment method

A mechanical cam type zoom lens device includes a movement position detector detecting movement positions of focus and zoom lenses moved by respective drivers, a reference compensation value calculating unit setting a plurality of zooming positions for a zoom lens when a focus lens is located at a predetermined focusing position and calculating an amount of movement from a predetermined focusing position in a case where the focus lens is adjusted to be in focus when the zoom lens is located at each set zooming position, the calculated amount of movement serving as a reference compensation value, a storage storing data of the reference compensation values, a focusing compensation value calculating unit calculating a focusing compensation value for the focus lens in a case where the zoom lens is located at the movement position, based on the set zooming positions, the reference compensation value read from the storage and the movement position of the zoom lens, and a focusing unit focusing the focus lens based on the calculated focusing compensation value so that the focus lens is focalized.

Growing community of inventors

Toyota, Japan

Masaaki Toguchi