Display Driver Reference Voltage Switching With Capacitor Precharge

Solution Overview

Problem

Existing display drivers face challenges in quickly turning on and off the reference voltage output of the reference voltage generation circuit, which affects the speed of the display driver's operation and power efficiency.

Innovation Solution

Incorporating a capacitor-based setting circuit that controls the voltage of the output node in response to an enable signal, allowing for rapid switching of the reference voltage output between on and off states, thereby enhancing the speed of the display driver's operation and power management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the reference voltage output is turned on/off by the reference voltage generation circuit, then power consumption of the amplifier circuit is reduced, but the switching speed becomes slow and driving duration is shortened

Engineering Contradiction:

Improvepower consumptionVSAvoidswitching speed

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The capacitor is pre-charged to a voltage higher than the reference voltage before switching is needed. When the enable signal is activated, this pre-charged capacitor immediately discharges through the reference current source, forcing the reference voltage output to rise rapidly to the target voltage level. This preliminary charging action eliminates the slow ramp-up that would normally occur, achieving both fast switching and power savings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the voltage at the output node using the capacitor's charge/discharge behavior. Instead of a static voltage generation approach, the system uses dynamic voltage transition controlled by the enable signal and capacitor timing characteristics. This allows the reference voltage to switch states rapidly while maintaining the ability to save power when in the off state.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If the reference voltage output switching is slowed down to ensure stable operation, then power saving is improved, but the driving duration is reduced and high speed driving becomes difficult

Engineering Contradiction:

Improvepower savingVSAvoiddriving duration

Core Design Contradiction:

Loss of energyVSDuration of action of moving object

Solution Approach 1:

The capacitor is pre-charged to a voltage higher than the reference voltage before switching is needed. When the enable signal is activated, this pre-charged capacitor immediately discharges through the reference current source, forcing the reference voltage output to rise rapidly to the target voltage level. This preliminary charging action eliminates the slow ramp-up that would normally occur, achieving both fast switching and power savings.

Inventive Principle:

Principle #10Preliminary action

3Speed

If a capacitor is used to speed up startup of the reference voltage generation circuit, then startup speed is improved, but the ability to control on/off of reference voltage output remains undefined

Engineering Contradiction:

Improvestartup speedVSAvoidcontrollability

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The capacitor is pre-charged to a voltage higher than the reference voltage before switching is needed. When the enable signal is activated, this pre-charged capacitor immediately discharges through the reference current source, forcing the reference voltage output to rise rapidly to the target voltage level. This preliminary charging action eliminates the slow ramp-up that would normally occur, achieving both fast switching and power savings.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit monitors the enable signal state and automatically controls the capacitor's charge and discharge cycles. When the enable signal indicates a transition is needed, the control circuit activates the capacitor discharge path, creating a feedback-controlled switching mechanism that combines speed with precise controllability.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables high-speed turning on and off of the reference voltage output, improving the display driver's performance by reducing the driving duration and conserving power.

Implementation Method 1

the setting circuit includes a capacitor having one end connected with the output node, and a control circuit configured to control a voltage of another end of the capacitor based on an enable signal, to change a voltage of the output node from a first voltage at which a reference current flowing in the reference current source is off, toward the reference voltage side

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10948939B2Display driver, circuit device, electro-optical device, and electronic apparatus

Publication Date: 2021.03.16 SEIKO EPSON CORP

AI summary

A display driver includes a driving circuit including an amplifier circuit and configured to cause the amplifier circuit to output a data voltage corresponding to display data, a reference voltage generation circuit configured to generate a reference voltage supplied to a reference current source of the amplifier circuit and output the reference voltage to an output node, and a setting circuit configured to set a voltage of the output node of the reference voltage generation circuit. The setting circuit includes a capacitor having one end connected with the output node, and a control circuit configured to control a voltage of another end of the capacitor based on an enable signal to change a voltage of the output node from a first voltage at which a reference current flowing in the reference current source is off, toward the reference voltage.