Hybrid Keyboard Subarray Scanning for Low-Power Key Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Contact-based switches in input devices, such as computer keyboards, suffer from wear-and-tear leading to unreliable performance and high power consumption, while contactless switches, though more reliable, consume significant power even when inactive.

Innovation Solution

Implementing a hybrid switch system combining contact-based and contactless switches, where the contact-based switch is used for low-power mode activation and the contactless switch for active mode, with subarrays to reduce the number of send/receive lines and optimize power usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contactless switches are used, then reliability is improved, but power consumption increases

Engineering Contradiction:

Improveswitch reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The keyboard is divided into multiple subarrays, each scanned independently. This segmentation allows the system to activate and scan only specific subarrays containing pressed keys rather than scanning the entire keyboard, thereby reducing overall power consumption while maintaining reliable key detection through the contactless switches.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system implements periodic scanning of subarrays at different intervals. Frequently used subarrays are scanned more often, while less active subarrays are scanned less frequently. This periodic action pattern reduces average power consumption while ensuring reliable detection of key presses through the contactless switch mechanism.

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If contact-based switches are used, then power consumption is reduced, but reliability deteriorates due to wear-and-tear

Engineering Contradiction:

Improvepower consumptionVSAvoidswitch reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent replaces the mechanical contact-based switch system with a contactless switch system that uses electromagnetic fields or optical fields to detect key presses. This substitution eliminates mechanical wear-and-tear, significantly improving reliability while the periodic scanning approach keeps power consumption manageable.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If full array scanning is performed, then all key presses are detected, but scanning time and power consumption increase

Engineering Contradiction:

Improvekey press detection accuracyVSAvoidscanning time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The keyboard array is segmented into multiple subarrays that can be scanned independently. When a key press is detected, only the specific subarray containing the pressed key is scanned in detail, rather than scanning the entire keyboard array. This segmentation approach maintains accurate key press detection while significantly reducing scanning time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs partial scanning of only the necessary subarrays rather than complete scanning of the entire keyboard. This partial action approach detects all relevant key presses while minimizing scanning time and power consumption by avoiding unnecessary scans of inactive subarrays.

Inventive Principle:

Principle #16Partial or excessive action

4Adaptability or versatility

If more send/receive lines are used, then more keys can be addressed, but PCB space and device complexity increase

Engineering Contradiction:

Improvekey addressing capabilityVSAvoidPCB space

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The keyboard is divided into multiple subarrays with independent scanning capabilities. This segmentation allows the system to address a large number of keys using fewer send/receive lines by scanning subarrays sequentially or selectively, rather than requiring dedicated lines for each key. This reduces PCB space requirements while maintaining high key addressing capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension to key addressing by scanning subarrays at different time intervals. Instead of requiring simultaneous physical connections to all keys, the system uses time-division multiplexing to address keys across multiple subarrays sequentially, effectively adding a time dimension to the addressing scheme and reducing the number of physical lines needed.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12444554B2Partial scanning in a hybrid switch array

Publication Date: 2025.10.14 LOGITECH EUROPE SA

AI summary

A keyboard system including a plurality of hybrid key structures configured in an array of subarrays, each of the plurality of hybrid key structures configured within a subarray and including a depressible element, a first type of key switch configured to generate a first signal when the depressible element is activated, a second type of key switch configured to generate a second signal when the depressible element is activated, and processor(s) configured to: receive a first signal from an activated hybrid key structure when its corresponding depressible element is activated; determine a corresponding subarray that the activated hybrid key structure is configured within; scan the corresponding subarray for a generated second signal; detect the generated second signal from the corresponding subarray; identify the activated hybrid key structure based on the detected, generated second signal; and register a key press for the identified activated hybrid key structure.