Touch Panel Stylus Contact Detection Using Elapsed Time
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Solution Overview
Problem
Conventional electronic whiteboards with optical touch panels face challenges in accurately detecting stylus position and mode switching, leading to user burden and awareness requirements for switching between draw and erase modes.
Innovation Solution
A display device with a touch panel, a coordinate detecting unit, a special pen detecting unit, and a timer unit that issues events based on stylus contact and elapsed time, allowing for automatic mode switching without user awareness of the current mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a threshold is set for light intensity detection to determine stylus contact, then the touch panel can detect stylus position, but the threshold cannot be accurately matched to the physical contact point across the entire display surface due to mechanical precision limitations and light dispersion
Solution Approach 1:
The patent changes the detection parameter from light intensity threshold to time measurement. By measuring the elapsed time from coordinate detection to stylus contact detection, the system can accurately determine contact without requiring precise mechanical alignment or threshold calibration across the display surface.
Solution Approach 2:
The patent introduces a timer as an intermediary measurement mechanism. Instead of directly measuring light intensity or position, the system uses time elapsed as an intermediate parameter to indirectly determine stylus contact, thereby avoiding the need for precise mechanical arrangements.
2Reliability
If the threshold is set with margin above the physical contact point to ensure detection, then the touch panel can reliably detect stylus contact, but the detection point becomes inconsistent with the actual contact position
Solution Approach 1:
The patent performs preliminary coordinate detection when the stylus approaches the display surface, then measures the time elapsed until actual contact is detected. This preliminary action allows the system to capture both the approach and contact events, enabling accurate position determination without threshold margin errors.
3Adaptability or versatility
If conventional mode switching methods are used (menu clicking or tray sensor detection), then the system can switch between draw and erase modes, but the user must be aware of the current mode and follow specific switching procedures
Solution Approach 1:
The system automatically determines the current mode by analyzing the relationship between coordinate detection and stylus contact detection timing, without requiring user awareness or manual switching commands. The mode switches automatically based on the detected interaction pattern, making the system self-adaptive to user intent.
Solution Approach 2:
The system uses feedback from the timing relationship between coordinate detection and stylus contact detection to automatically determine and switch modes. The detected time elapsed provides feedback about user intent, enabling automatic mode adjustment without explicit user commands.
4Measurement precision
If special pens with pressure sensors are used to detect stylus contact, then accurate contact detection is possible, but the system requires additional hardware and cannot detect contact with ordinary stylus or finger
Solution Approach 1:
The patent creates a universal detection method that works with any object interrupting the light (ordinary stylus, finger, or special pen) by measuring time elapsed rather than relying on pressure sensor signals. This multi-functional approach maintains precision while accommodating various input devices.
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
Reduces user burden by enabling seamless switching between draw and erase modes without requiring awareness of the current mode, improving usability and reducing accidental activations.
Implementation Method 1
an optical touch panel determines whether a stylus is inserted into the display surface, that is, whether the stylus is brought into contact with the display surface based on whether the light (hereinafter, referred to as probe light) disposed near the display surface is interrupted or reflected by a predetermined amount
Implementation Method 2
an optical touch panel determines whether a stylus is inserted into the display surface, that is, whether the stylus is brought into contact with the display surface based on whether the light (hereinafter, referred to as probe light) disposed near the display surface is interrupted or reflected by a predetermined amount
Data Source
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AI summary
A display device includes a touch panel (10); a coordinate detecting unit (11) configured to detect coordinates on a display surface of the touch panel (10); a special pen detecting unit (21) configured to detect that a special pen (20) comes into physical contact with the display surface; a timer unit (354) configured to measure time having elapsed from when the coordinate detecting unit (11) detects the coordinates; and an event issuing unit (351) configured to issue a first event when the special pen detecting unit (21) detects the special pen (20) coming into contact with the display surface, and issue a second event when the time having elapsed measured by the timer unit (354) exceeds a predetermined time Δt while the special pen detecting unit (21) is not detecting the special pen (20) coming into contact with the display surface.