Light-emitting element array driver circuit

Abstract

A driver IC of a light-emitting diode array head for an electronic photograph printer includes a current mirror circuit having a reference element and at least an output element so as to produce a reference current by use of a digital signal as an input thereto, a reference current source capable of outputting a plurality of reference current values, a selection circuit for specifying and selecting one of a plurality of reference current values from the reference current source, to be applied as an input current to the current mirror and an output control circuit for controlling the on and off states of an output current to be supplied to the output element of the current mirror circuit in accordance with a light emission control signal externally supplied. In connection with such a driver IC for a light-emitting diode array, there is implemented, furthermore, a bidirectional data scan with a reduced number of register circuits by employing in connection with n-data lines constituting a data bus, a group of register blocks each one thereof having n registers and which are operatively coupled so as to provide image data stored in the n registers to a plurality of driver circuits which switch ON/OFF the correspondingly associated light-emitting diodes. Furthermore, in connection with the register blocks, the driver also employs a bidirectional shift register for sequentially providing corresponding timing signals to each of the memory blocks.