Power Supply Circuit for LCD Common Electrode Voltage Control

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Solution Overview

Problem

Active matrix type LCD panels face challenges in reducing power consumption while maintaining high image quality and grayscale accuracy, leading to unnecessary power consumption due to fixed common electrode voltage supply capabilities that do not adapt to varying grayscale demands.

Innovation Solution

A power supply circuit that alternately supplies high-potential and low-potential voltages to the common electrode, with controlled current drive capability and output voltage levels adjusted based on grayscale data, using high-potential and low-potential voltage generation circuits to optimize voltage supply according to the total value calculated from converted grayscale data for each scan line.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the power supply capability of the common electrode voltage is determined taking into consideration the maximum value of the amount of electric charge to be charged and discharged, then the reliability of voltage supply is improved, but unnecessary power consumption occurs when the power supply capability is not required

Engineering Contradiction:

Improvevoltage supply reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The power supply capability of the common electrode voltage is made dynamically adjustable based on the actual drive requirements. The circuit can change its output capability from a fixed maximum value to variable levels corresponding to different grayscale requirements, thereby reducing unnecessary power consumption while maintaining reliability when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of power supply capability from a fixed maximum value to variable levels that correspond to different grayscale requirements. By adjusting the power supply capability parameter according to the actual drive requirements, the system reduces unnecessary power consumption while maintaining reliability when needed.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the number of colors and grayscale are increased, then the image quality is improved, but the power consumption increases due to accurate and high drive capability requirements

Engineering Contradiction:

Improvegrayscale accuracyVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent adjusts the power supply capability parameter according to the actual grayscale requirements. By changing the power supply capability from a fixed maximum to variable levels matching the drive requirements, the system achieves accurate grayscale display without unnecessary power consumption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of always operating at full power supply capability, the system uses only the necessary power level required for the current grayscale display task. This partial action approach reduces power consumption while maintaining the required grayscale accuracy.

Inventive Principle:

Principle #16Partial or excessive action

3Use of energy by moving object

If the voltage level applied to the pixel electrode is decreased, then the power consumption is reduced, but the image quality is affected due to horizontal crosstalk problems

Engineering Contradiction:

Improvepower consumptionVSAvoidimage quality

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent dynamically adjusts the power supply capability parameter to match the actual drive requirements. By optimizing the power supply capability according to the voltage levels and grayscale requirements, the system maintains image quality while reducing power consumption.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7609256B2Power supply circuit, display driver, electro-optical device, electronic instrument, and method of controlling power supply circuit

Publication Date: 2009.10.27 SEIKO EPSON CORP

AI summary

A power supply circuit including: a high-potential-side voltage generation circuit which generates a high-potential-side voltage; a low-potential-side voltage generation circuit which generates a low-potential-side voltage; and a switch circuit which alternately supplies the high-potential-side voltage and the low-potential-side voltage to the common electrode as a common electrode voltage. The power supply circuit performs supply capability control of the common electrode voltage which changes at least one of current drive capability of the high-potential-side voltage generation circuit, an output voltage level of the high-potential-side voltage generation circuit, current drive capability of the low-potential-side voltage generation circuit, and an output voltage level of the low-potential-side voltage generation circuit according to a total value generated based on grayscale data for the number of dots of one scan line. The total value is a value obtained by sequentially adding a converted voltage value obtained by converting each piece of the grayscale data for the number of dots of one scan line according to a given grayscale characteristic.