Patent Application
20050030398
The invention relates generally to the field of image sensors and, more particularly, to such sensors having a color filter array for separating incoming light and having a substrate which absorbs and stores the separated light in separate regions of the substrate for permitting more efficient color separation.
Current image sensors use a variety of methods for creating color separation. One such method uses the differences in absorption length in silicon of light of different wavelengths for color separation, such as in U.S. Pat. Nos. 5,965,875 and 4,613,895. In this regard, the incoming light is stored in separate regions of the substrate according to its wavelength, and the pixels are arranged so that each pixel receives each color at distinct depths of the silicon.
Another method of producing color separation in image sensors uses color filter arrays, such as in U.S. Pat. No. 3,971,065. In this regard, color filters are placed over the image sensor, and the color filter separates the incoming light so that particular colors are directed onto particular portions of the image sensor, such as is used in the well-known Bayer pattern. In this arrangement, each pixel receives only one color so that interpolation is needed when the entire image is created therefrom.
Although the above method is satisfactory, they include drawbacks. Color cross-talk is an undesirable inherent feature in techniques based on wavelength dependent absorption depths. Color filter arrays suffer from lower sensitivity and aliasing artifacts due to the sampling of color information inherent to the approach. Therefore, an apparatus and method are needed for overcoming the above drawbacks.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, the invention resides in an image comprising a plurality of pixels; a substrate which is doped so that electrons generated (excited) at different depths in the substrate are sensed and a separate signal produced for electrons generated in each region within a pixel; and a color filter array comprising materials that selectively absorb specific bands of wavelengths over predetermined pixels so that wavelengths that pass through the filter array generate electrons at specific depths in the substrate that can be sensed for the separate regions.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
Advantageous Effect of the Invention
The present invention has the advantage of reducing color cross-talk while maintaining efficiency by combining depth dependent light absorption in the substrate and color separation using a color filter before the light enters the substrate. This provides the advantage of a color filter that provides highly efficient color separation and the well structure in the silicon that allows multiple colors per pixel to be collected.
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Those skilled in the art will readily recognize that other color filter configurations may be used without departing from the scope of the invention. For example, the sequence of the colors may be changed.
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The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention.
