Measuring device for contactless height and length measurement

Abstract

Measuring device for the contactless detection of height and position values ​​on keyboard instruments, in particular pianos and grand pianos, comprising: - a linearly movable measuring head along a guide rail, - a laser distance sensor for height measurement, - a length encoder to detect the horizontal position, - an integrated display for real-time display of the measurement data, - a microcontroller module with WLAN functionality for data transmission to external devices, - software for controlling and displaying the data on the device as well as for visualizing the data in real time on a connected PC (Excel via VBA macro).

Description

Technical area:

[0001] The invention relates to a measuring device for the precise measurement of mechanical and geometric parameters on acoustic keyboard instruments, in particular pianos and grand pianos. The device is used for the contactless determination of vertical and horizontal dimensions in the area of ​​the keyboard, action, string system, and scale length. State of the art:

[0002] In traditional piano making, the measurement of key heights / depth, adjustment parameters (release, pitch, catch, rise), string lengths, and bridge pressure are usually done manually using straightedges, distance gauges, and visual inspection. Some industrial systems (e.g., in series production at Yamaha) use laser measurement, but these are cost-intensive and limited to large-scale production. Portable, flexible systems for small-scale workshops do not exist. Description of the invention:

[0003] The invention is based on the combination of a high-resolution laser distance sensor with a linear position encoder for contactless determination of heights and lengths along a keyboard, piano or grand piano action, or scale length (string lengths / bridge pressure). The device is portable and designed to be moved along a guided rail along the keyboard, action, or string. An incrementally coded magnetic tape applied to the rail is read by a sensor to capture the exact position of each measurement. The laser sensor measures the vertical distance to the reference surface (e.g., key, hammer head, string).

[0004] The measuring device is controlled exclusively via an infrared remote control, eliminating mechanical buttons and preventing measurement errors caused by vibration. The readings are displayed on an integrated color display.

[0005] Measured data is transmitted directly to a connected device via a Wi-Fi connection (e.g., a PC with Excel analysis via a VBA macro). Power is supplied by a 9V power source (block battery / Li-ion rechargeable battery). Embodiment:

[0006] The device consists of a plastic housing with an integrated ESP32-S3-Zero microcontroller, a TFT color display, a laser distance sensor (e.g., Panasonic HG-C1050 / HG_C1100), a magnetic tape sensor, a Wi-Fi module, and an IR receiver. It is mounted on a sturdy aluminum guide rail. The magnetic tape glued to the rail allows for precise reading of the length position.

[0007] The laser sensor is mounted on a mechanically adjustable mount, allowing both vertical and horizontal adjustment. Vertical adjustment is achieved via an arm held by neodymium magnets, while horizontal positioning is achieved via a sliding unit to accommodate different key and mechanical geometries. By removing the device and rotating it 180°, even black keys can be measured without having to reposition the rail.

[0008] Application examples: “Key Level”: Measurement and documentation of key heights / key depth “Action Adjust”: Measurement of parameters of the retracted wing mechanism such as pitch, release, pitch, catch “String Level”: Measurement of string heights (string level) “Scale Design”: Two devices are wirelessly coupled to measure the sounding length and the appendage length; the bridge pressure can also be calculated Advantages of the invention: Non-contact, reproducible measurement Direct transmission and evaluation of data in real time No vibration or key errors due to completely external control Mechanically robust and can be used without attachment to the instrument Compatible with a wide range of keyboard types thanks to flexible adjustment Drawings:

[0009] The application does not contain any drawings. A schematic representation may be submitted later, but is not required for the disclosure of the technical teaching. A notice:

[0010] This description does not contain any additional technical features beyond those already filed in the application dated 11 April 2025.

Claims

[1] Measuring device for the contactless detection of height and position values ​​on keyboard instruments, in particular pianos and grand pianos, comprising: - a linearly movable measuring head along a guide rail, - a laser distance sensor for height measurement, - a length encoder to detect the horizontal position, - an integrated display for real-time display of the measurement data, - a microcontroller module with WLAN functionality for data transmission to external devices, - software for controlling and displaying the data on the device as well as for visualizing the data in real time on a connected PC (Excel via VBA macro). [2] Device according to claim 1, characterized by that operation is carried out exclusively via an infrared remote control in order to prevent measurement errors caused by touch. [3] Device according to one of the preceding claims, wherein the height measurement is carried out by a precision laser in the µm range of class 2. [4] Device according to one of the preceding claims, in which all components are integrated into a modular profile housing. [5] Device according to one of the preceding claims, wherein measurement data are stored locally and / or retrieved via WLAN or transmitted live to an external system. [6] Two identical devices that synchronize each other via Wi-Fi to determine the distance between the two units along a mechanical guide rail (system profile) using encoder data. The incrementally coded magnetic tape is glued onto the device for position referencing. This allows the length of a string to be measured (e.g., sounding length or appendage length) to be determined. In combination with the laser distance sensor, the bridge pressure can also be precisely measured. [7] Device according to one of the preceding claims, characterized by that it can be placed on the guide rail rotated by 180°, which makes it possible to switch between measuring white and black keys without having to rebuild or move the guide rail. [8] Device according to one of the preceding claims, characterized by The laser distance sensor is mounted for both horizontal (across the guide rail) and vertical (perpendicular to the keyboard) adjustment. Vertical adjustment is achieved via an arm secured with neodymium magnets, and the laser's height can be adjusted so that the sweet spot (focus) is exactly at the height of the keys. The horizontal fine adjustment allows adaptation to different key geometries, e.g., on very old instruments with shorter keys.