System and methods for depth imaging using conventional CCD image sensors

A method for depth imaging using a CCD image sensor, comprising:

• providing an optical lens for collecting light from a scene having objects in front of the lens;
• providing a CCD image sensor device arranged to receive light from the optical lens and having an array of pixels and having corresponding pixel charge storage elements;
• providing a light source for transmitting light pulses towards the scene responsive to a pulse control signal;
• providing timing signals to configure the CCD image sensor to collect and store charge from pixels including a VSUB control signal that clears the pixel charge storage elements, a first readout control signal that enables a transfer cell corresponding to a pixel in a first sub-array of pixels to store charge, and a second readout control signal that enables a transfer cell corresponding to a pixel in a second sub-array of pixels to store charge;
• in a background frame period, collecting a background charge A corresponding to light incident on the CCD sensor that is reflected ambient light from objects in front of the lens into a transfer cell in the first sub-array, and for a portion of the background frame period, collecting a background charge B corresponding to light incident on the CCD sensor that is reflected ambient light from objects in front of the lens into a transfer cell in the second sub-array;
• in a depth frame period, outputting a pulse from the light source, and collecting a depth charge A corresponding to light that is reflected from objects due to the ambient light and due to a portion of the reflected light from the pulse from the light source into a transfer cell in the first sub-array, and in a portion of the depth frame period, collecting a depth charge B corresponding to light that is reflected from objects due to the ambient light and due to a portion of the reflected light from the pulse from the light source into a transfer cell in the second sub-array;
• and
• performing a depth calculation using the background charge A and the background charge B and the depth charge A and the depth charge B, for each pixel in the array of pixels in the CCD image sensor.