Light-emitting element drive device and light-emitting device

Abstract

Power loss and heat output are reduced in a current drive circuit unit of a light-emitting element. A light-emitting element drive device drives N (where N is an integer of 1 or more) light-emitting element groups, and includes a drive voltage generating circuit used as a feedback path of a minimum voltage detection circuit, N current drive circuits, and N or fewer voltage adjustment circuits. The N light-emitting element groups each include at least one light-emitting element. The drive voltage generating circuit supplies a specified voltage from a voltage source to the N light-emitting element groups. The N current drive circuits the N light-emitting element groups by current through the voltage adjustment circuits. Of the N current drive circuits connected to the minimum voltage detection circuit, the current drive circuit with the lowest end voltage is used in the feedback loop of the drive voltage generating circuit. Even if there is a voltage difference between the end voltages of the light-emitting element groups, the end voltage of the current drive circuit is reduced by the voltage adjustment circuit to a voltage equal to or greater than the minimum voltage required for the current drive circuit to operate.

Dependencies are inferred from the claim text.