LCD Driving Circuit Voltage Booster Shift Register Integration
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices using Poly-Si TFTs require high operating voltages, leading to increased power consumption and costs due to the need for additional level shifters to convert signals from 3V to 9V, which is inefficient and expensive.
Innovation Solution
A system incorporating a shift register, a voltage booster, and a sample switch that operates at lower voltages, boosting pulse signals from 5V to 9V within the enable time to control sample switches, reducing power consumption and eliminating the need for additional level shifters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If level shifters are used to convert signal voltages from 3V to 9V in Poly-Si TFT LCD devices, then the threshold voltage of Poly-Si TFT can be overcome and signals can be processed correctly, but power consumption increases and additional components are required
Solution Approach 1:
The patent combines the level shifting function with the existing shift register circuitry by using the Q output of the shift register to control the sampling switch. This integration eliminates the need for separate level shifters, reducing component count and power consumption while maintaining the capability to process signals at the required voltage levels.
Solution Approach 2:
The shift register's Q output is utilized to directly control the sampling switch, allowing the circuit to self-regulate the voltage levels needed for proper signal processing. The existing circuit elements serve dual purposes: data shifting and voltage level control, eliminating the need for dedicated level shifting components.
2Reliability
If level shifters are added to convert voltages from 3V to 9V, then Poly-Si TFT threshold voltage is overcome, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the level shifting function with the shift register output stage. The Q output of the shift register directly controls the sampling switch, combining data transmission and voltage level control into a single circuit element, thereby reducing overall device complexity.
Solution Approach 2:
The shift register's Q output serves multiple functions: it transmits shifted data and simultaneously provides the control signal for the sampling switch. This multi-functionality reduces the need for separate dedicated components, simplifying the overall circuit architecture.
3Reliability
If shift registers operate at 9V to generate scan pulses, then TFTs can be conducted properly, but power consumption increases
Solution Approach 1:
The patent applies different voltage levels to different parts of the circuit as needed. The shift register operates at lower voltage for data shifting, while only the specific control signal for the sampling switch requires higher voltage. This localized voltage application reduces overall power consumption while maintaining necessary TFT conduction capability.
Data Source
AI summary
A system for displaying image includes a driving circuit of a liquid crystal displaying device. The driving circuit of the liquid crystal displaying device includes a shift register, a voltage booster and a sample switch. The shift register receives an input pulse signal and shifts the input pulse signal to output an output pulse signal. The voltage booster is electrically connected with the shift register to receive the output pulse signal, and generates a boost voltage to output a boost signal within the enable time of the output pulse signal. The sample switch is electrically connected with the voltage booster to receive the boost signal. The boost signal controls the sample switch to sample a data signal.