Image Raster Layouts
Here's the actual layout of the CCID80 silicon. Note that while the "official" imaging array is 2048 by 2048, there are "buffer" rows above and below. Some of the lowest rows of the lower buffer rows are covered with aluminum to block light, but some are sensitive to light.
The upper buffer rows are no different from the other rows in the imaging array: their labeling as buffer rows is arbitrary.
The "buffer columns" don't connect to the output ports, so they don't appear in the data. Not clearly shown in this diagram is the division of the imaging array and frame store into slices. Each slice has 512 columns. There are 11 "prescan" pixels in the serial register between the bottom corner of the slice and its corresponding output port.
Note that output ports A and C are on the left edges of their slices while B and D are on the right edges of their slices. A consequence of this is that the electronics read pixels from rows in the A and C slices left to right, but those in the B and D slices right to left (in all cases, the electronics read rows from bottom to top in these diagrams).
It is important to understand how this plays out electrically for simulation and calibration. Each slice has its own measurement chain and ADC. If you were to collect the data at the output of the ADC, here's the raster you'd see.
While the lower "buffer rows" are exposed to light, we dump their charge before starting to read individual pixels, so they don't correspond to anything in this raster. I include the upper "buffer rows" in the image here, as they don't really deserve special designation. The real distinction is illumination: the image pixels are exposed to light for the whole exposure time and the frame transfer time. The smear pixels are only exposed during the frame transfer time: they measure the excess charge in a column due to the unwanted exposure during frame transfer. The dark pixels are never exposed to light, and may be used to measure video bias.
Columns for each slice:
- Slice A: 1..11, 45..556, 2093..2103
- Slice B: 12..22, 1068..557, 2104..2114
- Slice C: 23..33, 1069..1580, 2115..2125
- Slice D: 34..44, 2092..1581, 2126..2136