Pixel arrays and imaging devices with reduced blooming, controllers and methods
A pixel array includes regular pixels for imaging, and special pixel sites interspersed among the regular pixels. When the regular pixels become saturated from bright illumination, at least some of their excess charges are removed by the special pixel sites. The removal can reduce or eliminate blooming. In some embodiments, the special pixel sites include special pixels. For imaging, the regular pixels of a group such as a sub-array provide regular outputs that are combined into a composite signal. The special pixels provide a special output. The special output of the group may optionally be added to the composite signal, which can increase the dynamic range.
1. An array, comprising:
at least one group of eight substantially similar regular pixels to capture image information and one special pixel site surrounded by the eight regular pixels, the eight regular pixels arranged in three contiguous rows and in three contiguous columns, each of the eight regular pixels configured to generate charges as a result of receiving a certain illumination and to store a respective regular maximum of the generated charges, but not to store excess charges generated beyond its respective regular maximum, the special pixel site having a surface area that is substantially equal to a surface area of any of the eight regular pixels, the special pixel site made differently than the regular pixels such that the special pixel site is configured to remove at least some of the excess charges at the certain illumination; and
a readout mechanism to combine outputs of the at least one group of the eight regular pixels into a composite output, the composite output selectively including an output of the special pixel site as part of the composite output based on an illumination value of the composite output of the at least one group of the eight regular pixels.
2. The array of claim 1 , in which
the special pixel site of the at least one group also includes a photodiode configured to generate charges as a result of receiving the certain illumination, and
the special pixel site of the at least one group is configured to remove the charges generated by the photodiode as a result of receiving the certain illumination.
3. The array of claim 1 , in which
each of the special pixel site and the eight regular pixels of the at least one group has a surface area of less than 16 μm 2 .
4. The array of claim 1 , in which
the array is made in a semiconductor substrate,
the eight regular pixels of the at least one group include regular wells formed into the semiconductor substrate,
the special pixel site of the at least one group includes a special well formed into the semiconductor substrate, the special pixel site being different from the eight regular pixels of the at least one group in that the special well is deeper than the regular wells, and
the excess charges are removed by migrating into the special well.
5. The array of claim 1 , in which the composite output is to render an image.