Touch Detection Noise Reduction via Time-Division Control
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Solution Overview
Problem
Existing display devices with touch detection functions face challenges in reducing noise, particularly due to limitations in drive signal frequency and increased power consumption from noise cancelling signal generators, which can lead to noise in power supply circuits.
Innovation Solution
A display device with a touch detection function that incorporates a control unit generating different frequency control signals for display and touch detection operations, allowing for time-division switching between display and touch detection modes, utilizing mutual and self-capacitance touch detection methods to minimize noise and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If drive signal frequency is limited for touch detection, then touch detection accuracy is improved, but noise reduction capability deteriorates
Solution Approach 1:
The patent applies periodic action by switching between display operation periods and touch detection periods in a time-division manner. During touch detection periods, the display is stopped and touch detection is performed at specific frequencies, while during display periods, normal display operation occurs. This periodic switching allows the system to achieve both accurate touch detection and noise reduction by separating these functions in time rather than frequency.
Solution Approach 2:
The patent changes operational parameters dynamically by switching between different operation modes (display mode and touch detection mode) with different frequency characteristics. The control unit adjusts the operating frequency based on the current mode - using higher frequencies for touch detection when needed and lower frequencies during display operation, thereby resolving the contradiction between detection accuracy and noise reduction.
2Object-affected harmful factors
If noise cancelling signal generator is added, then noise is reduced, but power consumption increases
Solution Approach 1:
The patent merges the display electrode and touch detection electrode into a single integrated structure. The same electrode serves dual purposes: displaying images during display periods and detecting touch during detection periods. This eliminates the need for separate noise cancelling signal generators and dedicated touch detection hardware, thereby reducing power consumption while still achieving noise reduction through time-division operation.
Solution Approach 2:
The patent implements multi-functionality by designing electrodes that perform both display and touch detection functions. The display electrode simultaneously acts as the touch detection electrode, and the control unit manages both functions by switching operation modes. This universal design removes the need for additional noise cancelling hardware, reducing overall power consumption.
3Object-affected harmful factors
If noise cancelling signal is applied, then noise in touch detection members is reduced, but noise in power supply circuit occurs
Solution Approach 1:
The patent extracts the noise problem from the touch detection members and addresses it differently. Instead of applying noise cancelling signals that can interfere with power supply circuits, the invention stops the display operation during touch detection periods, thereby eliminating the source of electromagnetic noise that would require cancelling. This approach removes noise at its source rather than attempting to cancel it, avoiding power supply circuit interference.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively stopping the display operation before performing touch detection. This prevents the generation of electromagnetic noise that would otherwise require cancelling signals. By eliminating the noise source in advance rather than reacting to it, the system avoids creating noise in the power supply circuit while still achieving quiet 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
The solution effectively reduces noise and power consumption by alternating between display and touch detection modes, utilizing distinct frequency control signals to optimize touch detection accuracy and operational efficiency.
Implementation Method 1
a plurality of touch detection electrodes that form electrostatic capacitance between the touch detection electrodes and the drive electrodes
Data Source
AI summary
A display device with a touch detection function includes a substrate, pixel electrodes arranged in a matrix in a display region on a plane parallel to the substrate, a display function layer having a function to display the image in the display region, drive electrodes provided facing the pixel electrodes, touch detection electrodes that form electrostatic capacitance between there and the drive electrodes, a control unit that generates a control signal to switch between a display operation period for applying a display signal between the pixel and drive electrodes and a display stop period for stopping the display operation. The control unit generates first and second control signals respectively having a first frequency and a second frequency that is different from the first frequency, and has first and second operation modes respectively including a period controlled by the first control signal and a period controlled by the second control signal.