Column drivers with selectable current sources

A constant-current passive-matrix array, comprising:

• a two-dimensional array of pixels disposed in pixel rows and pixel columns, wherein, for each of the pixel rows, all of the pixels in the pixel row are connected in common to a row wire and, for each of the pixel columns, all of the pixels in the pixel column are connected in common to a column wire;
• a row controller connected to the row wire for each of the pixel rows, the row controller operable to select the row wire for one of the pixel rows with a row-select signal;
• and
• a column controller connected to the column wire for each of the pixel columns,
• wherein, for each of the column wires,
• the column controller comprises a respective column-control circuit connected to the column wire,
• the column controller is operable to provide a pixel value to the respective column-control circuit connected to the column wire,
• the respective column-control circuit comprises constant-current sources and a constant-current-source selection circuit operable to individually and separately enable each of the constant-current sources with a constant-current-source selection signal in response to the pixel value, and
• outputs of the constant-current sources are electrically connected in parallel to the column wire and the constant-current sources are together operable to output a constant-current column-data signal in response to the constant-current-source selection signal.