• Fix LRF
There is only one adjustable element on the board of the reader. This is RV1601 variable resistor , I found that this resistor is responsible for contrast adjustment. The adjustment may be useful if some artifacts from the previous page are clearly seen. Please note, typically, small artifacts are always visible on the page, especially if previous page contained large dark areas (like menu).
Two images form the screen were taken at the same conditions. 5 switches were done between two different pages (selected to have nonoverlapped areas of text lines) to make sure that the image is freshly generated after several black refreshes. Left image corresponds to the most clockwise position of RV1601 resistor, the right one corresponds to the most counterclockwise position. A piece of white paper was put on the screen to provide color/brightness reference.
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Here are zoomed areas, the difference is clearly visible, on the right image there are artifacts from the previous page and the characters are thicker.