Capacitive Pen-Touch Detection With Temporary Output Inhibition
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Solution Overview
Problem
Existing position detection systems inaccurately determine touch positions due to temporary variations in region size 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 is detached from the touch surface, using a capacitive touch sensor with a processor to track and adjust detection criteria based on writing pressure and region size, switching operation modes to prevent erroneous detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the region size of the detected touch position is used to determine whether to output the touch position, then touches by palm or fist can be excluded, but touches by the pen-holding hand may be erroneously detected when the region size temporarily varies
Solution Approach 1:
The system activates an exclusive mode when the electronic pen is detected to be in contact with the touch surface. This preliminary action prevents touch position detection before the pen contact state can cause erroneous detections, resolving the contradiction by anticipating and preventing the measurement instability issue before it occurs
Solution Approach 2:
The system dynamically switches between time-sharing detection mode and exclusive mode based on the electronic pen's contact state. When the pen is in contact, the system transitions to exclusive mode where only pen position is detected. This dynamic adaptation allows the system to maintain reliable touch detection accuracy while accounting for the unstable region size measurements that occur during pen usage
2Reliability
If an exclusive mode is activated to stop detecting touches while allowing electronic pen detection, then unintended touches during pen input can be inhibited, but touches may be erroneously detected when the exclusive mode is cancelled
Solution Approach 1:
The system activates exclusive mode as a preliminary action when the electronic pen is detected to be in contact with the touch surface. This prevents unintended touches from being detected during pen input operations, resolving the contradiction by establishing a preventive mechanism before erroneous detections can occur
Solution Approach 2:
The system continuously monitors the electronic pen's contact state and uses this feedback to dynamically adjust the detection mode. When the pen is in contact, exclusive mode is maintained; when detached, the system transitions back to time-sharing mode. This feedback mechanism ensures timely and accurate mode switching, preventing both unintended and erroneous detections while maintaining appropriate response times
3Reliability
If the output of touch position is continuously monitored and temporarily inhibited after pen detachment, then erroneous detections can be prevented, but detection response time may be increased
Solution Approach 1:
The system temporarily inhibits touch position output as a preliminary measure immediately after detecting electronic pen detachment. This prevents erroneous detections from occurring during the transition period when region size measurements are unstable, resolving the contradiction by proactively blocking potential errors before they can affect the output
Solution Approach 2:
The system dynamically controls the touch position output based on the electronic pen's contact state. When the pen is in contact, output is inhibited; when detached, output is restored. This dynamic control mechanism balances reliability improvement with minimal time loss, as the inhibition is only active during the brief transition period when it is most needed
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 rendering by ensuring accurate and timely inhibition of touch position outputs, reducing errors in position detection during pen use.
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.