Bidirectional Shift Register Clock Sampling for LCD Circuit Area Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bidirectional shift registers require additional signals for switching shift directions, leading to increased circuit area and unnecessary pulses during shift actions, which complicates the operation and efficiency of liquid crystal display devices.
Innovation Solution
A bidirectional shift register design that uses sampling of a shift start signal through different clock signals to generate shift pulses for forward and backward shifts, eliminating the need for additional signals and reducing circuit area by synchronizing pulse generation with three or four-phase clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional signals are used to switch shift directions in bidirectional shift registers, then the shift direction can be controlled, but the circuit area increases and unnecessary pulses are generated
Solution Approach 1:
The clock signal serves multiple functions: it drives the normal operation of the shift register stages and simultaneously controls the shift direction switching. By making the clock signal universal for both timing and direction control, the patent eliminates the need for separate direction control signals, thereby reducing circuit area while maintaining bidirectional functionality
Solution Approach 2:
The patent merges the direction control function with the clock signal function. Instead of having separate signals for clocking and direction control, the clock signal's phase selection (through clock selection circuits) determines both the timing and the direction of shift operation, combining multiple control functions into a single signal pathway
2Adaptability or versatility
If additional signals are used to switch shift directions, then bidirectional operation is enabled, but the operation becomes more complex and inefficient
Solution Approach 1:
The shift register uses its own clock signal to control its own direction switching, eliminating the need for external direction control signals. The clock selection circuits within each stage automatically select the appropriate clock phase based on the desired shift direction, making the system self-controlling and reducing operational complexity
Solution Approach 2:
The patent implements dynamic clock phase selection where the clock signal phases are dynamically switched depending on the required shift direction. The clock selection circuits dynamically adjust which clock phase is applied to each stage, enabling flexible bidirectional operation without complex static control logic
3Adaptability or versatility
If frame memory is provided to reverse display image orientation, then the scanning sequence can be changed, but the configuration becomes more complex compared to bidirectional shift register
Solution Approach 1:
The patent extracts the scanning sequence control function from the main display processing path and implements it within the shift register itself. By taking out the direction control logic from external control circuits and embedding it in the clock selection circuits of the shift register stages, the configuration is simplified while maintaining the ability to switch scanning sequences
Data Source
AI summary
A signal obtained through sampling a gate start pulse signal GSP by using one of a plurality of gate clock signals is supplied as a shift pulse for a forward shift action (a forward shift start pulse signal) to the first stage of a plurality of stages constituting a bidirectional shift register, and a signal obtained through sampling the gate start pulse signal GSP by using another one of the plurality of gate clock signals is supplied as a shift pulse for a backward shift action (a backward shift start pulse signal) to the last stage of the plurality of stages constituting the bidirectional shift register.