Gamma Correction Circuit Power Reduction in Always-On Display Mode

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Solution Overview

Problem

Conventional gamma correction circuits for display devices face challenges in minimizing power consumption and chip area while providing various gamma curves, especially in always-on display (AOD) mode, due to limited voltage range and increased power consumption from static current and resistor column currents.

Innovation Solution

The proposed gamma correction circuit includes a third and fourth input amplifier that share reference voltages with first and second input amplifiers, deactivating the latter two in AOD mode to minimize power consumption, and uses a decoder and resistor columns to generate and distribute gamma voltages, allowing for low power operation without increasing layout size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional gamma correction circuit is used to provide various gamma curves, then gamma curve versatility is improved, but power consumption increases due to static current and resistor column currents

Engineering Contradiction:

Improvegamma curve versatilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The circuit dynamically switches between different operational modes (full gamma correction mode and AOD mode) by controlling the activation state of specific amplifiers based on display requirements. In AOD mode, only the third and fourth input amplifiers are activated while the first and second are deactivated, reducing power consumption while maintaining necessary gamma correction functionality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The gamma correction circuit is segmented into multiple independent input amplifiers (first, second, third, and fourth) that can be selectively activated. This segmentation allows the circuit to activate only the necessary amplifiers for specific operating modes, thereby reducing overall power consumption while maintaining gamma curve versatility.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If voltage range is expanded to control more gamma curves, then gamma curve versatility is improved, but chip area increases

Engineering Contradiction:

Improvegamma curve versatilityVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The third and fourth input amplifiers are designed to share reference voltage inputs with the first and second input amplifiers, allowing a single amplifier to serve multiple gamma curve generation functions. This multi-functionality enables the circuit to provide various gamma curves without proportionally increasing chip area.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Reference voltage inputs are merged and shared among multiple amplifiers rather than providing separate reference voltages to each amplifier. This sharing approach reduces the overall component count and chip area while maintaining the ability to generate multiple gamma curves.

Inventive Principle:

Principle #5Merging (Combining)

3Use of energy by moving object

If first and second input amplifiers are deactivated in AOD mode, then power consumption is reduced, but voltage range control may be limited

Engineering Contradiction:

Improvepower consumptionVSAvoidvoltage range control

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

Different amplifiers are optimized for different functional requirements: the third and fourth input amplifiers are specifically configured to handle the voltage range needed for AOD mode operation, while the first and second amplifiers handle full gamma correction ranges. This local optimization ensures that each amplifier performs its specific function efficiently.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10762825B2Gamma correction circuit and gamma correction method

Publication Date: 2020.09.01 DB GLOBALCHIP CO LTD

AI summary

Disclosed is a gamma correction circuit and method capable of minimizing power consumption by adding third and fourth input amplifiers receiving reference voltages which are identical to voltages to first and second input amplifiers, respectively, and deactivating the first and second input amplifiers during an always on display (AOD) mode. The gamma correction circuit includes a first input amplifier configured to output a maximum voltage when active, a second input amplifier configured to output a minimum voltage when active, a third input amplifier configured to output a highest gamma voltage in response to the first reference voltage, and a fourth input amplifier configured to output a lowest gamma voltage in response to the second reference voltage. The first and second input amplifiers are deactivated when the display driving device operates in the AOD mode.