Source Driver Resistor String Fluctuation Control

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Solution Overview

Problem

The existing source driver technologies face issues with output distortion due to fluctuations in the resistor string during the latch enable signal spread, leading to inaccurate grayscale voltages and a gray inversion phenomenon between neighboring rows or columns of interpolated grayscale data.

Innovation Solution

The source driver incorporates a latch, a resistor string, a decoder, and control switches to manage the selection and output of grayscale voltages, with first and second control switches alternately turned on and off based on synchronized and delayed control signals to prevent resistor string fluctuations and maintain accurate resistance values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If decoders sequentially select grayscale voltages from a common resistor string during latch enable signal spread, then data can be stored and converted across multiple channels, but the resistor string fluctuates and cannot maintain accurate resistance values

Engineering Contradiction:

Improvedata conversion speed across channelsVSAvoidresistor string resistance accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent divides the operation into two distinct phases: a first period where the resistor string is exclusively used for grayscale voltage selection without interference, and a second period where latch enable signals are spread across channels. This temporal segmentation prevents simultaneous access conflicts and maintains resistance accuracy during critical selection operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by completing all grayscale voltage selections from the resistor string before the latch enable signals are asserted. By finishing the voltage selection process in advance, the resistor string is released from service before channels begin operating, preventing any fluctuation during the selection period.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If latch enable signals are spread over time intervals to different latches, then sequential data processing can occur, but output distortion occurs due to resistor string fluctuations affecting decoders

Engineering Contradiction:

Improvesequential latch operationVSAvoidoutput signal accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent extracts the resistor string from service during the latch enable signal spread period. By removing the resistor string from the active circuit during the second period when latches are being enabled sequentially, it prevents any potential fluctuations from affecting the decoder outputs and ensures reliable signal accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

All necessary grayscale voltage selections are performed in advance during the first period before latch enable signals are distributed to channels. This preliminary completion of voltage selection ensures that no resistor string access occurs during the sequential latch operation, eliminating output distortion.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If a common resistor string is shared by multiple decoders, then circuit complexity is reduced, but gray inversion phenomenon occurs between neighboring interpolated rows or columns

Engineering Contradiction:

Improveresistor string configurationVSAvoidgrayscale voltage accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements periodic action by alternating between two distinct operational periods: a first period dedicated to resistor string access for grayscale selection, and a second period for latch enable signal distribution. This periodic alternation ensures that the common resistor string is never accessed during latch operations, preventing gray inversion while maintaining the simplicity of the shared resistor string architecture.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10586498B2Source driver and display apparatus including the same

Publication Date: 2020.03.10 DB GLOBALCHIP CO LTD

AI summary

A source driver includes a latch configured to store data based on or in response to a latch signal and output the data stored in the latch, a resistor string including a plurality of resistors configured to provide a plurality of grayscale voltages, a decoder connected to the resistor string, configured to select and output one of the plurality of grayscale voltages based on or in response to the data from the latch, an amplifier including a first input terminal, a second input terminal and an output terminal, a first control switch between the decoder and the first input terminal of the amplifier, and a second control switch between the first input terminal and the second input terminal of the amplifier. The first control switch and the second control switch are alternately turned on and off.