Display Driver Circuitry Using Scan and Global Drive Phases

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Solution Overview

Problem

Large electro-optic displays face challenges with high power consumption and significant transmission line effects due to high frequency drivers and the need for numerous local drivers, which are costly and complex to implement and maintain.

Innovation Solution

A method involving a scan phase followed by a global drive phase, where pixels are enabled and disabled in a scan frame using inexpensive drivers, allowing a single drive circuit to provide a complex voltage sequence, reducing the number of drivers required and minimizing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If active matrix approach is used to drive large electro-optic displays, then display update capability is improved, but power consumption increases and driver cost increases

Engineering Contradiction:

Improvedisplay update capabilityVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements a two-phase periodic driving scheme: a scan phase where pixel states are set using inexpensive drivers, followed by a global drive phase where a single driver applies voltage sequences to transition enabled pixels to desired states. This periodic alternation between selective scanning and global driving reduces average power consumption compared to continuous high-frequency active matrix driving.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The display update process is segmented into distinct phases: scan phase for setting pixel states and global drive phase for transitioning display states. This segmentation allows different driving strategies to be applied at different times, using simple drivers for scanning and a single driver for global transitions, thereby reducing overall power consumption and driver complexity.

Inventive Principle:

Principle #1Segmentation

2Productivity

If active matrix approach is used to drive large electro-optic displays, then display update capability is improved, but driver complexity increases

Engineering Contradiction:

Improvedisplay update capabilityVSAvoiddriver complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the driving function into a single driver circuit that performs both scanning operations and global drive operations. During the scan phase, the driver selectively enables pixels; during the global drive phase, the same driver applies voltage sequences to all enabled pixels. This consolidation eliminates the need for multiple local drivers required in active matrix approaches, significantly reducing driver complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If direct drive approach is used to mount electronics on back of printed circuit board, then transmission line effects are reduced, but number of drivers increases

Engineering Contradiction:

Improvetransmission line effectsVSAvoidnumber of drivers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a universal driver that performs multiple functions: it conducts scanning operations to set pixel states and also performs global drive operations to transition display states. This single multi-functional driver replaces the numerous specialized local drivers that would be required in a direct drive architecture, reducing driver count while maintaining reliability by keeping the driver close to the display.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Device complexity

If scan phase followed by global drive phase is used, then number of drivers is reduced, but update time increases

Engineering Contradiction:

Improvenumber of driversVSAvoidupdate time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The scan phase performs preliminary action by setting the state of each pixel (enabled or disabled) before the global drive phase begins. This preliminary classification of pixels allows the subsequent global drive phase to efficiently transition only the enabled pixels to their desired states, optimizing the overall update time despite the two-phase structure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The periodic alternation between scan phase and global drive phase creates an efficient update rhythm. The scan phase prepares pixel states, and the global drive phase executes transitions in parallel for all enabled pixels. This periodic structure balances the time required for selective scanning with the efficiency of parallel global transitions, achieving acceptable update times with reduced driver count.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11398197B2Methods and circuitry for driving display devices

Publication Date: 2022.07.26 E INK CORP

AI summary

A display device is operated by using several iterations of a scan phase followed by a global drive phase. In the scan phase, the state of each pixel in the display device is set to either “enabled” or “disabled”, during which time a global drive generator is inactive. Then, in the global drive phase, a global drive signal is sent to the display device. Only the subset of enabled pixels is affected by the global drive signal, which causes the enabled pixels to perform a transition to a desired display state. The sequence of the scan phase followed by the global drive phase is then repeated up to the number of unique transitions required to update the display device.