Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2007-10-01
2008-10-21
Tran, Thuy Vinh (Department: 2821)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C315S250000, C315S294000, C315S324000
Reexamination Certificate
active
07439945
ABSTRACT:
A Light-Emitting Diode (LED) driver circuit is disclosed that controls the brightness of light generated by a LED that is coupled between a first terminal and a second terminal in response to a user supplied brightness control signal. A constant current source generates a constant current that is supplied to the LED and to a shunt circuit, which his connected in parallel with the LED. A brightness control circuit generates a pulse signal having a duty cycle that is proportional to the brightness control signal, and controls the shunt circuit such that, when said pulse signal is high, the constant current is passed through the shunt circuit and the LED is turned off, and when the pulse signal is low, the constant current is passed through the LED. The duty cycle of the brightness control signal is adjusted to adjust the LED's brightness, while the LED color remains constant.
REFERENCES:
patent: 6586890 (2003-07-01), Min et al.
patent: 6867757 (2005-03-01), Nakamura
patent: 7317403 (2008-01-01), Grootes et al.
patent: 2007/0229001 (2007-10-01), McIntosh et al.
Awalt Thruston
Deng Qi
Bever Patrick T.
Bever Hoffman & Harms LLP
Micrel Incorporated
Tran Thuy Vinh
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