EP 0672324 A4 19951206 - GAMMA CORRECTION CIRCUIT FOR USE IN IMAGE PROJECTORS.
Title (en)
GAMMA CORRECTION CIRCUIT FOR USE IN IMAGE PROJECTORS.
Title (de)
GAMMA-KORREKTURSCHALTUNG ZUR VERWENDUNG IN BILDPROJEKTOREN.
Title (fr)
CIRCUIT DE CORRECTION GAMMA POUR PROJECTEURS D'IMAGES.
Publication
Application
Priority
- EP 96103231 A 19960302
- US 9311306 W 19931119
- US 98610892 A 19921204
Abstract (en)
[origin: WO9414276A1] Apparatus that implements a nonlinear transfer function (gain) that provides for gamma correction of nonlinear image projectors. The nonlinearity of the transfer function is designed to compensate for the nonlinear light modulator, such as a liquid crystal light valve and cathode ray tube combination, for example, that is used in the image projector. The gamma correction circuit comprises a plurality of amplifiers (30a, 30b, 30c) that include current sources coupled together to sum their output currents, and each amplifier is adapted to implement a predetermined transfer function, and provide differing levels of current. An optional output resistor (RC) may be employed to convert the composite ouptut current into a correponding output voltage. Each of the plurality of amplifiers typically comprises first and second emitter coupled pair transistors (31, 32) plus their associated current sources. This invention corrects the grey scale linearity of the image projector and produces "soft" breakpoints, creating a relatively smooth transfer function.
IPC 1-7
IPC 8 full level
H04N 5/202 (2006.01); H04N 5/74 (2006.01); H04N 9/69 (2006.01)
CPC (source: EP)
H04N 5/202 (2013.01); H04N 5/7441 (2013.01)
Citation (search report)
[A] US 4868668 A 19890919 - TAVERNETTI RUSSELL E [US]
Designated contracting state (EPC)
BE DE FR GB IT NL
DOCDB simple family (publication)
WO 9414276 A1 19940623; DE 672324 T1 19961010; EP 0672324 A1 19950920; EP 0672324 A4 19951206; JP H08506700 A 19960716
DOCDB simple family (application)
US 9311306 W 19931119; DE 94902334 T 19931119; EP 94902334 A 19931119; JP 51418793 A 19931119