Bidirectional Scanning Drive Circuit for Display Devices
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Solution Overview
Problem
Existing display devices face challenges in reducing circuit size while maintaining bidirectional scanning functionality, as the configuration required to stop clock signals during scanning increases waste and costs.
Innovation Solution
A display device with a drive circuit that includes a first-stage output circuit, utilizing a start signal and multiple clock signals where the conducting potential periods do not overlap, and employing transistors to manage signal potentials efficiently, allowing for bidirectional scanning without stopping the clock signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If clock signals are stopped during bidirectional scanning, then scanning control is simplified, but circuit size increases and cost increases
Solution Approach 1:
The clock signals CK1-CK4 continue to operate continuously without stopping during bidirectional scanning operations. This eliminates the need for additional control circuits that would be required to stop and restart clock signals, thereby reducing overall circuit size while maintaining simplified scanning control through the continuous clock operation combined with the specific transistor switching sequence
2Area of stationary object
If the same start signal is used for both forward and backward scanning, then circuit size is reduced, but scanning reliability deteriorates due to potential signal conflicts
Solution Approach 1:
The circuit dynamically responds to the same start signal VST by using the current scanning direction state (controlled by transistors Q1-Q4) to determine which clock signals are active. During forward scanning, clocks CK1-CK4 operate in one sequence, while during backward scanning, the same clocks operate in a different sequence. This dynamic adaptation allows the use of a single start signal without conflicts while maintaining scanning reliability
Solution Approach 2:
The circuit employs periodic clock signals CK1-CK4 that are activated in different sequences depending on the scanning direction. The same start signal triggers periodic scanning operations, and the clock signals are periodically switched between forward and backward scanning sequences based on the direction state, ensuring reliable operation while using minimal circuitry
Data Source
AI summary
A display device includes a first-stage output circuit adapted to perform output to a first-stage output signal line as an endmost output signal line out of a plurality of output signal lines disposed in parallel to each other, and the first-stage output circuit includes a start signal line to which a start signal for applying a conducting potential sequentially to the plurality of output signal lines is applied, a first clock signal line to which a first clock signal is applied, a second clock signal line to which a second clock signal is applied, a first transistor having a source to which the first-stage output signal line is connected, and a drain to which the first clock signal line is connected, and a second transistor having a gate to which the start signal line is connected.