Shared Input-Output Pin Control Circuit for Display and Touch
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Solution Overview
Problem
The increasing complexity of electronic devices with multiple input-output pins for touch and display devices leads to reduced space in electronic devices, as the control circuit requires more pins than the sum of the touch and display devices' pins to function effectively.
Innovation Solution
A control circuit design that shares input-output pins between a display device and a capacitive touch device, using a sensing circuit to determine touch events by setting voltage levels and detecting changes, allowing for reduced pin count through the use of switching circuits and microcontroller control to manage signal transmission during both display and sensing periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control circuit uses separate input-output pins for both the display device and the capacitive touch device, then the connection reliability is improved, but the number of pins increases leading to reduced space in the electronic device
Solution Approach 1:
The patent combines the input-output pins for the display device and the capacitive touch device into a shared pin structure. The same physical pin serves dual purposes: transmitting display signals during display periods and sensing touch signals during sensing periods, thereby reducing the total pin count while maintaining functional reliability through time-division multiplexing
Solution Approach 2:
The control circuit implements periodic switching between display mode and sensing mode. During display periods, pins transmit display signals; during sensing periods, the same pins are used to detect touch events. This periodic alternation allows a single pin to fulfill multiple functions without compromising the reliability of either function
2Area of stationary object
If the control circuit shares input-output pins between display and touch devices, then the space usage is reduced, but the complexity of signal management increases
Solution Approach 1:
The control circuit employs periodic time-division multiplexing to manage pin sharing. By alternating between display periods and sensing periods in a regular cycle, the system simplifies signal management through predictable, rhythmic switching rather than complex ad-hoc control, reducing the cognitive and computational burden of managing shared pins
Solution Approach 2:
The sensing circuit is designed to automatically detect touch events by monitoring voltage changes on shared pins during sensing periods without requiring complex external intervention. The circuit self-manages the transition between display and sensing functions, reducing the overall system complexity
3Speed
If the sensing circuit detects touch events during the display period, then the touch detection speed is improved, but the display quality deteriorates due to signal interference
Solution Approach 1:
The system implements strict periodic separation between display operations and touch sensing operations. Display signals are transmitted during display periods while touch sensing occurs during dedicated sensing periods. This temporal separation prevents signal interference that would occur if both operations attempted to use the same pins simultaneously, ensuring display quality is maintained while still achieving timely touch detection
Solution Approach 2:
The control circuit proactively switches to sensing mode immediately after completing a display period, anticipating the need for touch detection. This preliminary transition ensures that touch events are detected as quickly as possible without compromising the current display frame, maintaining both display quality and responsive touch detection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the number of input-output pins needed in the control circuit, minimizing space usage while maintaining effective touch detection and display functionality without interfering with the display device's operation.
Implementation Method 1
a sensing circuit (920)... determines whether the capacitive touch device (520) is touched according to the voltage of the first input-output pin (IOA0) and the voltage of the second input-output pin (IOB0)
Data Source
AI summary
A control circuit including a first input-output pin, a second input-output pin, a sensing circuit and a display controller is provided. The first input-output pin is configured to be coupled to a first input pin of a display device and a first sensing pin of a capacitive touch device. The second input-output pin is configured to be coupled to a second input pin of the display device and a second sensing pin of the capacitive touch device. The display controller provides a first driving signal to the display device via the first input-output pin and providing a second driving signal to the display device via the second input-output pin in a display period. In a first sensing period, the voltage level of the first input-output pin is equal to a first predetermined level, and the sensing circuit detects the voltage of the second input-output pin.