PHOTOGRAPHIC DEVICE AND CONTROL METHOD THEREFOR

• US 20090096902A1
• Filed: 12/11/2008
• Published: 04/16/2009
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Koji Kobayashi
• Original Assignee: Koji Kobayashi
• Inventors: Kobayashi, Koji
• Granted Patent: US 7,903,169 B2
• Time in Patent Office: Days
• US Class Current: 348/296
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

There is disclosed a photographic device that uses an image sensor and an electronic viewfinder. When a release button is pressed halfway, an aperture value, an electronic shutter speed and a photosensitivity are decided based on the present subject brightness to provide a proper exposure value for photographing a still image. So long as the release button is kept being pressed halfway, a timing generator drives the image sensor to shoot video images at a frame rate of 20 Hz, and the aperture value decided for still image photography is fixed, whereas the electronic shutter speed and the photosensitivity are adjusted according to the subject brightness by use of an aperture-priority type video program. When the release button is pressed to the full, an exposure for a still image is done with the fixed aperture value.

Claims

1. A photographic device comprising:

an image sensor having a function of an electronic shutter that gives effect to charging from when electronic shutter pulses stop being input in said image sensor;

a drive device generating drive signals including said electronic shutter pulses for driving said image sensor in predetermined frame periods, said electronic shutter pulses being generated from the start of each frame period; and

a control device that selects from among different frame periods the shortest one of those frame periods which permit charging during an exposure time for still image photography, as determined according to a subject brightness, decides timing of stopping inputting said electronic shutter pulses so as to provide said determined exposure time, and sets the selected frame period and the decided timing in said drive device in response to a release signal entered to start photographing a still image.

2. A photographic device as claimed in claim 1, further comprising a mechanical shutter that is movable between an open position letting photographic light into said image sensor and a closed position blocking photographic light from said image sensor, and is moved from said open position to said closed position when a given time has elapsed since the start of a frame period for photographing a still image, wherein said control device selects the frame period and decides the timing of stopping inputting said electronic shutter pulses so as to make a time duration from the stop of inputting said electronic shutter pulses to the blocking of photographic light by said mechanical shutter equal to said decided exposure time.

3. A photographic device as claimed in claim 1, wherein said drive device is a timing generator that validates at the start of each frame period contents as set therein by said control device, and said control device sets up said timing generator for still image photography and initializes synchronizing operation of said timing generator immediately after the entry of said release signal, thereby to restart said synchronizing operation and start a frame period for still image photography immediately after said timing generator is set up for still image photography.

4. A control method for a photographic device using an image sensor having a function of an electronic shutter wherein electronic shutter pulses are input in said image sensor from the start of each frame period, and effective charging in said image sensor starts from when said electronic shutter pulses stop being input, said control method comprising steps of:

determining an exposure time for still image photography according to a subject brightness;

selecting from among different frame periods the shortest one of those frame periods which permit charging during said exposure time;

deciding timing of stopping inputting said electronic shutter pulses so as to provide said exposure time; and

photographing a still image in the selected frame period and the decided timing in response to a release signal.