Digital camera synchronization
View Patent ↗The present invention provides a synchronization system comprising a base unit and at least one video camera. The base unit includes a master time-base adapted to set a time period that samples a frame of video data, a memory, and a base unit communications transceiver. The base unit communications transceiver is adapted to transmit a frame synchronization signal to a video camera communications transceiver. The video camera includes an image sensor adapted to store the video data, an exposure control adapted to control an exposure level of the image sensor, and a camera time-base adapted to receive the frame synchronization signal from the video camera communications transceiver. The camera time-base is further adapted to receive the frame synchronization signal, reset its time and initiates its internal timing sequence, transmit signals to the exposure control to control a length of the exposure, and transmit timing signals to the image sensor to read the video data.
1. A synchronization system for a plurality of video cameras comprising:
a base unit, including:
a master time-base adapted to generate a master synchronization signal defining a frame period within which a frame of video data is captured;
a base unit communications transceiver adapted to transmit the frame synchronization signal; and
a video camera, including:
a video camera communications transceiver adapted to receive the frame synchronization signal from the base unit and transmit video data to the base unit;
a camera time-base adapted to reset a camera time-base value in response to reception of the frame synchronization signal and wherein the camera time-base is configured to operate during a camera time-base period following said reset wherein the camera time-base period is less than the frame period;
an image sensor adapted to store video data; and
an exposure controller adapted to monitor a value of the camera time-base and, upon detecting the value of the camera time-base matching a predetermined value, initiate exposure of the image sensor.
2. The synchronization system of claim 1 , wherein the base unit further includes a memory and wherein the camera time-base is further adapted to control the image sensor to read the video data and transmit the read video data to the memory.
3. The synchronization system of claim 2 , wherein the camera time-base is adapted to end the exposure period when transmission of the read video data to the base unit communications transceiver completes.
4. The synchronization system of claim 2 , wherein timing signals associated with the received read video data are converted to timing signals of the master time-base when the memory receives the read video data.
5. The synchronization system of claim 2 , wherein a time period to complete reading the frame of video data is less than the frame synchronization period.
6. The synchronization system of claim 1 , further comprising a plurality of video cameras, wherein the base unit communications transceiver is adapted to send a plurality of frame synchronization signals to a plurality of video camera communications transceivers.
7. The synchronization system of claim 1 , wherein the camera time-base is further adapted to control the exposure controller to terminate exposure of the image sensor, and wherein neither the initiation nor the termination of the exposure coincide with the frame synchronization signal.
8. A video camera comprising:
an image sensor adapted to store video data;
a communications transceiver adapted to receive a frame synchronization signal from a base unit and transmit video data to the base unit;
a camera time-base adapted to reset a time-base value in response to receiving the frame synchronization signal and wherein the camera time-base is configured to operate during a camera time-base period following said reset and terminate operation when the camera time-base period expires; and
an exposure controller adapted to monitor a value of the camera time-base and, upon detecting the value of the camera time-base matching a first predetermined value, initiate exposure of the image sensor, and, upon detecting the end of the camera time-base period, terminate exposure of the image sensor.
9. The video camera of claim 8 , wherein the camera time-base is further adapted to control the exposure controller to terminate exposure of the image sensor, and wherein neither the initiation nor the termination of the exposure coincide with the frame synchronization signal.
10. An operational method for a video camera, comprising:
responsive to receiving a frame synchronization signal from a base unit, resetting a value of a time-base and initiating a time-base period;
responsive to detecting the value of the time-base matching a predetermined value stored in an exposure controller, initiating exposure of an image sensor;
initiating a reading of video data stored in the image sensor at least partially during said exposure of said image sensor; and
responsive to detecting at least one of a completion of said exposure of said image sensor and the value of the time-base reaching a predetermined maximum value, terminating the exposure of the image sensor.