Keystroke detection device, keyboard, and keystroke detection method

Apparatus (1) for detecting a key press comprising a circuit substrate (2), a key module (4) attached to the circuit substrate (2) with a key cap (3), and a movement mechanism (15) for moving the key cap (3) relative to the circuit substrate (2) between a rest position and an actuation position, and a device (10) for detecting the movement of the key cap (3) relative to the circuit substrate (2),

• wherein this device (10) comprises an electrical resonance circuit (11) with at least one capacitor (C1) and with at least one primary coil (L1) stationary in relation to the circuit substrate (2) with one or more coil windings and comprises at least one secondary coil (L2) with a short-circuited winding, which secondary coil is moved with the key cap (3),
• wherein the primary coil (L1) is arranged on a rear side of the key module (4) opposite the key cap (3) on or in the circuit substrate (2),
• wherein the secondary coil (L2) is a secondary coil element (5) which comprises or consists of a conductive material, which material has a continuous recess (13), so that the conductive material surrounding this recess (13) is the short-circuited winding of the secondary coil (L2),
• wherein the primary coil (L1) and the secondary coil (L2) are inductively coupled to one another, and the strength of the inductive coupling between the primary coil (L1) and the secondary coil (L2) and thus at least one physical variable of the resonance circuit (11) change during the movement of the key cap (3) and thus the secondary coil (L2) between rest position and actuation position,
• wherein the device (10) for detecting the movement of the key cap (3) relative to the circuit substrate (2) comprises a measuring device for detecting and/or processing at least one physical variable of the electrical resonance circuit (11), which variable changes during the movement of the key cap (3) and the secondary coil (L2) between the rest position and the actuation position, and outputs at least one electrical signal dependent on the change in the physical variable.