Display Driver Output Buffer With Current-Based Power Gating

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Solution Overview

Problem

Conventional display devices suffer from high power consumption due to a fixed static current in the output buffer after charging or discharging pixel capacitors, which is not efficiently managed.

Innovation Solution

An output buffer design that includes an operational transconductance amplifier and a detector to control the output stage, allowing the output buffer to be turned on/off based on output current, thereby reducing power consumption by eliminating static current when charging or discharging is complete.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the output buffer operates continuously to maintain readiness for pixel charging/discharging, then the response speed is improved, but the power consumption increases due to fixed static current

Engineering Contradiction:

Improveresponse speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The output buffer transitions from a static continuous operation state to a dynamic state where it can be turned on and off. The enabling signal dynamically controls the output stage, allowing the buffer to be activated only when pixel charging or discharging is required, thereby reducing static current consumption while maintaining fast response when needed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The output buffer operates in periodic cycles rather than continuously. It is activated during specific periods when pixel voltage adjustment is needed and deactivated during other periods, creating a pulsed operation pattern that eliminates continuous static current drain while preserving operational readiness

Inventive Principle:

Principle #19Periodic action

2Loss of energy

If the output buffer is turned off to reduce power consumption, then the energy efficiency is improved, but the response time increases when activation is needed

Engineering Contradiction:

Improveenergy efficiencyVSAvoidresponse time

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The detector continuously monitors the output current to detect when pixel charging or discharging is needed, triggering the enabling signal in advance. This preliminary detection mechanism ensures the output buffer is activated at the optimal moment, minimizing any potential delay while still allowing it to remain off during idle periods to save energy

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the output buffer operates with fixed static current to ensure stability, then the operational reliability is improved, but the power consumption increases unnecessarily

Engineering Contradiction:

Improveoperational reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control is applied locally to the output stage rather than the entire output buffer. The enabling signal specifically controls the output stage's connection to the pixel, allowing the operational amplifier to remain in a low-power standby state while still providing controlled output current when needed, thus maintaining reliability only where necessary while reducing overall power consumption

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11735085B1Output buffer capable of reducing power consumption of a display driver

Publication Date: 2023.08.22 HUANG YING NENG

AI summary

An output buffer for a source driver of a panel includes an output stage, configured to output an output voltage; an operational transconductance amplifier (OTA), configured to control the output stage to charge or discharge a capacitor of a pixel of the panel; and a detector, coupled between the OTA and the output stage, configured to output an enabling signal to turn on/off the output buffer after the output buffer finishes charging or discharging the capacitor of the pixel of the panel, wherein the enabling signal is determined according to a current value of the output stage.