Segmented Resistor String for Display Gamma Optimization

Solution Overview

Problem

Existing display technologies face issues with gamma settling time, power supply rejection ratio (PSRR), and output voltage offset, which affect image quality and visibility, particularly in liquid crystal displays (LCDs) due to unbalanced resistor strings in gamma units.

Innovation Solution

Incorporating a segmented resistor string with modified resistance values in the display control circuitry, where processing circuitry monitors and adjusts resistor segments to optimize display performance parameters such as settling time, PSRR, and output voltage offset, maintaining the desired gamma curve while reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional unsegmented resistor string is used in the gamma unit, then the circuit is simple, but the settling time is excessive and PSRR is insufficient

Engineering Contradiction:

Improvedisplay performanceVSAvoidresistor string structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The resistor string is divided into multiple segmented resistors (R1, R2, R3, R4) with different resistance values, allowing independent optimization of each segment to improve settling time and PSRR while maintaining the overall gamma curve characteristics

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resistor segments are assigned different resistance values tailored to specific gray level ranges, enabling localized optimization of display performance parameters in different brightness regions without affecting the entire circuit uniformly

Inventive Principle:

Principle #3Local quality

2Loss of time

If resistor segments are modified to reduce settling time, then settling time improves, but power consumption increases

Engineering Contradiction:

Improvesettling timeVSAvoidpower consumption

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The resistor string is divided into multiple segmented resistors (R1, R2, R3, R4) with different resistance values, allowing independent optimization of each segment to improve settling time and PSRR while maintaining the overall gamma curve characteristics

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resistance values are assigned to different resistor segments based on the desired gamma curve and performance requirements, enabling optimization of settling time and PSRR while controlling power consumption through parameter adjustment

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If gamma correction is improper, then image brightness is affected, but the underlying cause is unoptimized resistor configuration

Engineering Contradiction:

Improveimage brightnessVSAvoidresistor configuration

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

Different resistor segments are assigned different resistance values tailored to specific gray level ranges, enabling localized optimization of display performance parameters in different brightness regions without affecting the entire circuit uniformly

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The gamma unit uses the segmented resistor configuration to provide feedback control of the gamma curve, allowing optimization of image brightness and contrast through adjusted resistor values that compensate for display non-linearities

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11081032B2Display circuitry and method to utilize segmented resistors for optimizing front of screen performance

Publication Date: 2021.08.03 APPLE INC

AI summary

Aspects of the subject technology relate to control circuitry for displays. A display control circuitry includes a plurality of amplifiers to drive gamma signals for a pixel array having a plurality of pixels of a display and a segmented resistor string coupled to the plurality of amplifiers. The resistor string includes a plurality of resistor segments with a resistor segment being designed with a modified resistance to modify display performance parameters including at least one of a settling time of an associated gamma signal, a power supply rejection ratio (PSRR) of an amplifier of the plurality of amplifiers, or an output voltage offset of an amplifier of the plurality of amplifiers.