Dialog Semiconductor Gmbh

Helmut Burkhardt

Achim Stellberger

Hans Martin Von Staudt

Michael Keller

Paul Zehnich

Frank Kronmuller

Rolf Hülβ

Rolf Nülss

A circuit and methods eliminating production related luminance variations of electronic display applies to all display technologies that require gamma adjustment or also adjustment of other display parameters e.g. brightness or contrast as e.g. LCD or OLED display modules are disclosed. This is performed by individual trimming of the display driver's gamma curve One alternative is that an end-user has access to a non-volatile memory and replaces the factory default settings of the gamma curve with individual settings. Another alternative is to load gamma curve parameters from the non-volatile memory to gamma control registers and perform tweaking of the gamma curve from these control registers on top of the factory default settings in the non-volatile memory.

Gamma curve correction for TN and TFT display modules

A self-trim circuit provides a technique to trim a CUT (circuit under trim) using a LSB offset to determine the best digital value to trim the CUT. The self-trim circuit is also used to self-test the digital and analog portions of the self-trim circuitry, whereby the existence of a digital stuck at fault condition is detected. A state machine controls a digital stack to couple digital trim data to the CUT and read the output of a comparator circuit that signifies when a proper digital trim value has been used. Thereafter the proper digital trim value is stored into a nonvolatile memory.

Self-trim and self-test of on-chip values

A circuit and a method for an effective way to customize the display driver software of any type of LCD-display and any type of LCD-driver chip used in an LCD display system is achieved. This is important in a multiple sourcing environment where LCD driver chips and LCD modules from different vendors are used in LCD display systems. This is accomplished through identification and registration of the information relevant for the said software customization by storing said information in an LCD module identification register. A microprocessor controlling the LCD display system is reading this identification register and providing the software customization elements specific to the LCD-driver chip and to the LCD-module during an initialization step of the system.

LCD module identification

Growing community of inventors

Heidelberg, Germany

Helmut Burkhardt