Patent ID: 7696962

Claim:
A color balancing circuit for a display panel having a panel surface on which a plurality of picture elements, each including a red light-emitting element, a green light-emitting element, and a blue light-emitting element, are arranged in a matrix, the color balancing circuit including: a reference voltage generator for generating a reference voltage; a primary adjustment block for varying the reference voltage according to a brightness adjustment signal having a user-selectable value designating a single primary brightness for the red, green, and blue light-emitting elements alike, and converting the varied reference voltage to a primary current, the primary adjustment block comprising a voltage divider for dividing the reference voltage to obtain a plurality of divided voltages, and a selector for selecting one of the divided voltages according to the brightness adjustment signal; a red adjustment block connected to the primary adjustment block for generating a red adjusted current related to the primary current by a ratio selected according to a red adjustment signal having another user-selectable value; a green adjustment block connected to the primary adjustment for generating a green adjusted current related to the primary current by a ratio selected according to a green adjustment signal having yet another user-selectable value; a blue adjustment block connected to the primary adjustment for generating a blue adjusted current related to the primary current by a ratio selected according to a blue adjustment signal having still another user-selectable value; three drivers for generating red, green, and blue driving currents from the red, green, and blue adjusted currents, respectively; and three output stages for generating output currents from the red, green, and blue driving currents and supplying the output currents to the red, green, and blue light-emitting elements, causing the red, green, and blue light-emitting elements to emit light; wherein each of the red, green, and blue adjustment blocks separately comprises; a first current mirror circuit with a plurality of transistors connected in parallel to mirror the primary current in the converter circuit; and a plurality of switches connected in series with respective ones of said plurality of transistors, the switches being controlled by the red adjustment signal to generate the red adjusted current in the red adjustment block, by the green adjustment signal to generate the green adjusted current in the green adjustment block, and by the blue adjustment signal to generate the blue adjusted current in the blue adjustment block; wherein said plurality of transistors have mutually identical dimensions; and wherein said plurality of transistors are laid out in a row and said switches are controlled to feed current through a selectable subset of said plurality of transistors disposed symmetrically about a center of said row.