Electronic Piano Key Switch Contact Shift Tolerance
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Solution Overview
Problem
Conventional three-contact key switches for electronic pianos face issues with erroneous operations due to movable contact position shifts, leading to inaccurate key depression information detection, and struggle to maintain stable contact pressure, which affects the reliability and accuracy of key depression information.
Innovation Solution
The key switch design features stationary contacts with extended portions between non-common contacts and an elastic switch body with pressure-receiving protuberances that allow for sequential contact establishment and maintain contact stability, even with slight deviations in movable contact positions, preventing erroneous operations and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the stationary contacts are arranged closely to reduce switch size, then the device complexity is reduced, but movable contact position shifts cause erroneous operations and detection accuracy deteriorates
Solution Approach 1:
The common contact is divided into a body portion and an extended portion. The extended portion protrudes toward the non-common contact to create a segmented structure that increases the allowable range for movable contact shifts while maintaining compact overall dimensions.
Solution Approach 2:
The extended portion of the common contact is arranged in the front-rear direction (lengthwise direction of the key), which is orthogonal to the left-right direction where the common and non-common contacts are opposed. This dimensional arrangement allows the extended portion to bridge gaps without increasing the switch's width or height.
2Volume of moving object
If the common contact and non-common contact are closely opposed to reduce switch size, then the device complexity is reduced, but contact stability deteriorates when movable contact positions shift
Solution Approach 1:
The common contact is segmented into a body portion and an extended portion. The extended portion acts as a buffer zone that maintains stable contact with the movable contact even when its position shifts, preventing erroneous operations.
Solution Approach 2:
The extended portion of the common contact serves as an intermediary element between the movable contact and the non-common contact. It provides a larger contact area that compensates for positional deviations, ensuring reliable signal transmission.
3Reliability
If the allowable range for movable contact shifts is increased to prevent erroneous operations, then the reliability is improved, but the switch size increases
Solution Approach 1:
By segmenting the common contact into body and extended portions, the patent creates a compact structure where the extended portion provides additional contact area without significantly increasing the overall switch volume.
Solution Approach 2:
The extended portion utilizes the front-rear direction (lengthwise direction) for its extension, which allows increasing the allowable shift range without expanding the switch's width or height, thus maintaining a compact form factor.
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
This design increases the allowable range for movable contact shifts without increasing the switch size, ensuring reliable and accurate detection of key depression information, maintaining contact stability and preventing faulty operations.
Implementation Method 1
the elastic switch body is pressed by the pivotal member to be deformed
Data Source
AI summary
A key switch for an electronic piano, which makes it possible to increase an allowable range for shift of a movable contact without increasing the size of the key switch of the three-contact type. The key switch includes a substrate having first to third stationary contacts arranged thereon side by side in the lengthwise direction of a pivotal member as one of a key and a hammer. Each stationary contact has a common contact and a non-common contact. The common contact has an extended portion extending between two non-common contacts. The key switch has first to third movable contacts arranged side by side on an elastic switch body, for being sequentially brought into contact with the common contacts and non-common contacts of the stationary contacts as the switch body is pressed by the pivotal member, to thereby output signals indicative of key depression information.