Position Detection Circuit with Pen-Detachment Touch Inhibition
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Solution Overview
Problem
Existing position detection systems inaccurately determine touch positions due to temporary variations in the size of the region of contact caused by the user's hand movement when using an electronic pen, leading to unintended outputs to the host processor.
Innovation Solution
A position detection circuit and method that inhibits the output of touch positions temporarily when the electronic pen detaches from the touch surface, tracks the region size, and switches operation modes to prevent erroneous detections based on writing pressure values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system outputs touch position when region size is within predetermined range, then finger touch detection accuracy is improved, but erroneous detection of pen-holding hand touches increases
Solution Approach 1:
The system activates an exclusive mode before pen detachment occurs, based on prediction of upcoming pen detachment. This preliminary action prepares the system to inhibit touch position output, preventing erroneous detection of pen-holding hand touches that would otherwise occur when the hand temporarily reduces contact region size after pen detachment
Solution Approach 2:
The system continuously monitors pen detection status and uses this feedback to dynamically control touch position output. When pen detachment is detected or predicted, the system provides feedback to inhibit touch position output, creating a closed-loop control that adapts to changing operational states and prevents erroneous detections
2Reliability
If exclusive mode is activated to prevent unintended touch detection, then erroneous touch detection is reduced, but touch detection capability is lost during pen input
Solution Approach 1:
The system dynamically switches between time-sharing mode and exclusive mode based on pen detection state. During pen contact, exclusive mode prevents erroneous detection; upon pen detachment, time-sharing mode restores touch detection capability. This dynamic adaptation resolves the contradiction by making the system flexible rather than statically restricted
Solution Approach 2:
The system periodically evaluates pen detection status and adjusts operational mode accordingly. This periodic assessment ensures that exclusive mode is activated only when necessary (during pen input) and deactivated when appropriate (after pen detachment), maintaining touch detection availability while preventing erroneous detections during critical periods
3Reliability
If touch position output is inhibited after pen detachment, then erroneous detection of pen-holding hand touches is prevented, but legitimate finger touches may be missed temporarily
Solution Approach 1:
The system inhibits touch position output in advance based on prediction of pen detachment, rather than waiting for actual detachment to occur. This preliminary inhibition prevents the brief period where erroneous detection could occur while the hand transitions from pen-holding to free state, eliminating the need for subsequent correction delays
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
Prevents unintended touch position outputs by ensuring accurate detection and reducing erroneous determinations, enhancing user-intended rendering accuracy.
Implementation Method 1
a capacitive touch sensor constituted by a plurality of sensor electrodes arranged two-dimensionally
Data Source
AI summary
Provided is a position detection circuit for detecting a position of an electronic pen and a position of a passive pointer on a touch surface disposed on a capacitive touch sensor constituted by a plurality of sensor electrodes arranged two-dimensionally, the electronic pen being configured to be capable of transmitting a pen signal, the passive pointer not transmitting any signal, the position detection circuit configured to detect a touch position indicative of the position of the passive pointer, and output the touch position if a size of a region forming the touch position is within a predetermined range, in which, if the electronic pen was in contact with the touch surface and becomes detached therefrom, the output of the touch position is temporarily inhibited.