The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 18, 1998
Filed:
Feb. 20, 1997
Yukio Aizawa, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A driver circuit of a light-emitting device that is able to reduce the current consumption. This circuit includes a reference current source for generating a reference current, a cascode current source circuit for generating a driving current for the light-emitting device with the use of the reference current, and an input circuit for switching the driving current according to a data signal. The cascode current source circuit has a first current mirror formed by first and second transistors and a second current mirror formed by third and fourth transistors. The first transistor is supplied with a first constant current proportional to the reference current, and controls the second transistor so that the driving current flows through the second transistor. The third transistor is supplied with a second constant current proportional to the reference current, and generates a mirror current with respect to the second constant current. The second mirror current flows through the second transistor as the driving current. The input circuit serves to turn on and off the fourth transistor according to the data signal, thereby controlling the output of the driving current to the light-emitting device.