Display Driver Short-Circuiting Control Circuit for Voltage Delay
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Solution Overview
Problem
In high-definition display systems, the delay caused by parasitic capacitance and wiring resistance in output amplifier circuits can result in voltage values not reaching the desired level within the horizontal scanning period, leading to image quality degradation.
Innovation Solution
A display driver with a reference gradation voltage generator and short-circuiting control circuit that selects and amplifies reference gradation voltages, allowing for the short-circuiting of lines to accelerate voltage changes, ensuring that the desired voltage values are reached within the horizontal scanning period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the horizontal scanning period is shortened to achieve high-definition display, then the display resolution is improved, but the voltage value cannot reach the desired level within the scanning period due to delay caused by parasitic capacitance and wiring resistance
Solution Approach 1:
The invention applies preliminary action by pre-charging the first line with a reference gradation voltage through the voltage supply part before the actual gradation voltage is needed. This preparatory charging reduces the time required for the line to reach the desired voltage level when the horizontal scanning period is shortened, thereby resolving the contradiction between high display resolution and insufficient voltage reaching time.
2Device complexity
If the same gradation voltage is provided to both inputs of the output amplifier to simplify the circuit, then the device complexity is reduced, but the delay time is prolonged due to increased wiring capacitance
Solution Approach 1:
The invention applies segmentation by dividing the voltage supply path into two separate lines (first line and second line) with different functions. The first line receives the actual gradation voltage while the second line receives a reference gradation voltage. This segmentation allows each line to be optimized independently, reducing the total equivalent capacitance and delay time compared to using a single line for both inputs, thereby resolving the contradiction between circuit simplicity and delay time.
3Speed
If the wiring resistance and parasitic capacitance are reduced to decrease delay time, then the voltage reaching speed is improved, but the manufacturing precision requirements are increased
Solution Approach 1:
The invention introduces a reference gradation voltage as an intermediary element that is supplied to the second line. This reference voltage serves as a mediator to pre-charge the wiring and reduce the delay time without requiring extreme reductions in wiring resistance or parasitic capacitance. The reference voltage acts as a buffer that facilitates faster voltage transition while maintaining reasonable manufacturing precision requirements.
Data Source
AI summary
A display driver includes: a plurality of decoders that converts a plurality of pixel data pieces representing luminance levels for pixels into gradation voltages having magnitudes corresponding to the luminance levels represented by the pixel data pieces, respectively; a plurality of amplifiers that provides a plurality of driving voltages obtained by amplifying the gradation voltages to a plurality of data lines of a display device, respectively; and a reference gradation voltage generator that generates a plurality of reference gradation voltages having respective different voltage values corresponding to gradation levels. Each of the decoders includes a short-circuiting control circuit that controls whether to short-circuit between a first line and a second line of each of the decoders.