Push-Pull Output Isolation for Shared Stylus Electrode Reception

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Solution Overview

Problem

Existing digital pens or styluses face challenges in efficiently sharing an electrode for both transmitting and receiving data to and from a digitizer, particularly due to the need to switch a high voltage push-pull driver to a high impedance mode with low parasitic capacitance, which is costly, power-intensive, and adds significant size.

Innovation Solution

A method and device that determine whether to transmit or receive information via an electrode, isolating the electrode from the transmitter circuit when receiving data to enable high impedance mode operation with low parasitic capacitance, allowing simultaneous data transmission and reception using time division multiplexing or separate electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the high voltage push-pull driver is switched to high impedance mode to share the electrode for receiving data, then the electrode can be used for both transmission and reception, but the parasitic capacitance increases significantly and the device becomes more costly and power-intensive

Engineering Contradiction:

Improveelectrode sharing capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic switching between push-pull driver modes (high voltage, low voltage, and high impedance) based on operational requirements. The system transitions to high impedance mode only when receiving data, and maintains low parasitic capacitance through controlled impedance switching, thereby enabling electrode sharing while managing power consumption and parasitic effects dynamically.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

Engineering Contradiction:

Improveelectrode sharing capabilityVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent enables the single electrode to serve multiple functions (transmission and reception) by implementing high impedance mode switching in the push-pull driver. This multi-functionality eliminates the need for separate transmit and receive electrodes, thereby reducing overall device size while maintaining full bidirectional communication capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the electrode is shared for both transmission and reception, then the communication functionality is improved, but signal interference occurs between transmitting and receiving operations

Engineering Contradiction:

Improvebidirectional communicationVSAvoidsignal integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements periodic switching between transmission and reception modes using high impedance state transitions. The push-pull driver alternates between active transmission states and high impedance reception states in a time-division multiplexed manner, allowing bidirectional communication while preventing simultaneous transmission-reception conflicts and maintaining signal integrity.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11016589B2Discrete high impedance implementation on push-pull outputs

Publication Date: 2021.05.25 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Methods and devices for communicating or interacting by a pen or a stylus with a digitizer are disclosed. An example method describes determining whether the device is to transmit a first information to the digitizer via the electrode or receive a second information from the digitizer via the electrode. An example device for use with the method includes a transmitter circuit, a receiver circuit, and an electrode. The method further includes isolating the electrode from the transmitter circuit in response to determining that the device is to receive the second information from the digitizer via the electrode.