Demux Control Circuit for LCD Driver Pin Reduction
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Solution Overview
Problem
High-resolution liquid crystal display devices face challenges with a large number of pins required in the driving IC, leading to increased costs and complexity due to the need for multiple control signals for switching elements.
Innovation Solution
A demux control circuit that converts two or three pulse signals from a driving chip into multiple control signals using NOR gates and buffers, reducing the number of pins needed and integrating inverting control signals to manage signal stages effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple control signals are provided to control switching elements in a demux, then the switching elements can be controlled to turn on or off the output terminals, but the number of pins required in the driving IC increases
Solution Approach 1:
A logic circuit is introduced as an intermediary between the driving IC and the demux switching elements. The logic circuit receives a reduced number of control signals from the driving IC and generates the required multiple control signals for the switching elements, thereby reducing the pin count requirement while maintaining full control capability
Solution Approach 2:
The control signal generation function is segmented into two parts: the driving IC provides basic control signals, and the logic circuit segments this control into multiple independent control signals for different switching elements, allowing the driving IC to have fewer pins while the system maintains full control functionality
2Ease of manufacture
If the number of pins in the driving IC is reduced, then production costs decrease, but generating multiple control signals becomes more challenging
Solution Approach 1:
The logic circuit performs multiple functions: it receives control signals from the driving IC, generates multiple independent control signals for different switching elements, and can provide both normal and inverted control signals. This multi-functionality allows a single logic circuit to replace what would otherwise require multiple separate control pins in the driving IC
Solution Approach 2:
The logic circuit creates copies of control signals with different logical states (normal and inverted) to control different switching elements. Instead of requiring separate physical pins for each control signal, the logic circuit generates multiple control signals from fewer input pins, reducing the pin count while maintaining control capability
Data Source
AI summary
The present application provides a demux control circuit. The demux control circuit includes a driving chip, a logic circuit, and a demux for providing two or three pulse signals to the logic circuit, the logic circuit including a plurality of NOR Gate and a plurality of buffers which can convert two pulse signals into three control signals or convert the three pulse signals into four control signals through the cooperation of the NOR gates and the buffers to achieve outputting a larger number of control signals by a smaller number of pins, thereby reducing the number of pins outputted from the driving chip and reduce production costs.