Image sensor with focus-detection pixels, and method for reading focus-information
AssigneeHarvest Imaging bvba
InventorAlbert Theuwissen
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Abstract
An image sensor (810) comprises a plurality of image pixels (R, G, B) and a plurality of focus-pixels (F), each focus-pixel comprising a light shield (51a, 51b) for partly shielding the focus-pixel from incident light so as to obtain a focus-related signal in a first mode of operation. The image sensor further comprises additional circuitry for processing the focus-related signal, which additional circuitry is conveniently located underneath the light shields. The additional circuitry may be adapted for accumulating the charge of two focus-pixels (F1a, F2a), e.g. by charge binning, and for providing the accumulated charge in a second mode of operation.
Claims9
An image sensor comprising:
- a plurality of image pixels;
- and
- a plurality of focus-pixels, each focus-pixel comprising circuitry for converting incident light into an electrical signal and for allowing read-out of the electrical signal, and a light shield for partly shielding the focus-pixel from the incident light so as to obtain a focus-related signal;
- characterized in that the image sensor further comprises additional circuitry for processing the focus-related signal delivered by the focus pixels, wherein the additional circuitry is physically located underneath the light shields of said focus pixels.
A method for reading focus information from an image sensor comprising a plurality of image pixels and a plurality of focus-pixels, the plurality of focus-pixels comprising at least a first and a second focus-pixel forming a first pair, and a third and a fourth focus-pixel forming a second pair, the pair of focus-pixels comprising a pair of corresponding light shields for partly shielding the focus-pixels from incident light so as to obtain focus-related information, each focus-pixel being adapted for storing an amount of charge dependent on the incident light, and for providing the focus-related signal in a first mode of operation;
- the image sensor further comprising circuitry for accumulating the charge of the first and the third focus-pixel forming a first couple, and for accumulating the charge of the second and the fourth focus-pixel forming a second couple, and for providing the accumulated charges as the focus related signals in a second mode of operation, the circuitry comprising active elements being located under the light shields of the focus-pixels, the method comprising the steps of:
- 1) in one step, obtaining focus information from the image sensor configured in the first mode, and
- 2) in another step, determining lighting information from the focus information, and if the lighting information is below a predefined threshold, reading focus information from the image sensor configured in the second mode;
- or, alternatively
- 3) in one step, obtaining focus information from the image sensor configured in the second mode, and
- 4) in another step, determining lighting information from the focus information, and if the lighting information is above a predefined threshold, reading focus information from the image sensor configured in the first mode.
Dependencies are inferred from the claim text.