Patent ID: 8054324
Filing Date: 2011-11-08
Classification: B41J

Abstract:
1. An optical head comprising a plurality of unit regions repeatedly arrayed in one direction, each region being constituted by a light-emitting element which is driven by a current to emit light, a control transistor which is connected in parallel with the light-emitting element, and which receives gray-scale data that specifies a high gray-scale level for the light-emitting element so as to be turned off and which receives gray-scale data that specifies a low gray-scale level for the light-emitting element so as to be turned on, and a driving transistor which is connected in series with the light-emitting element to generate a current, wherein, in each of the plurality of unit regions, a thermal resistance between the light-emitting element formed in the unit region and the control transistor formed in the unit region is smaller than a thermal resistance between the light-emitting element and a control transistor formed in a unit region adjacent to the unit region, wherein the optical head is composed of a plurality of layers, the light-emitting element has a laminated light-emitting portion which emits light by flow of a current therethrough, the light-emitting element does not overlap both the control transistor and the driving transistor as viewed from a direction vertical to the light-emitting portion in each of the plurality of unit regions, and the control transistor and the driving transistor are formed on opposite sides of the light-emitting element as viewed from the direction vertical to the light-emitting portion in each of the plurality of unit regions.