CS268908B1 - Inductive contactless keyboard - Google Patents

Abstract

The solution concerns an inductive contactless keyboard for contactless generation of alphanumeric character codes for computing and control technology. The basic element of this keyboard is a ferromagnetic switch-encoder, consisting of a split core with a rectangular hysteresis curve, the movable part of which is mechanically coupled to the keyboard button. An excitation wire and n sensing wires pass through the core. In the rest position, the magnetic circuit of the core is interrupted by an air gap and the excitation current is not enough to remagnetize them. By pressing the button, the core closes, its magnetic resistance decreases, the excitation current remagnetizes the core and a voltage is induced in its sensing wires, which is adjusted to the required logic level by the output circuit. This circuit also blocks the output of an incorrect code when multiple buttons are pressed using a blocking wire that passes through the cores of all buttons except for the function buttons that generate additional bits. The release signal "button pressed" is derived from the blocking pulses.

Description

The present invention relates to an inductive contactless keyboard for contactless generation of an alphanumeric character code for computer technology. At the same time, non-contact keyboards are manufactured using Hall probes and moving magnets coupled with buttons, or I work on a capacitive principle. The code is generated in electronics, which is expensive.

These disadvantages are eliminated by keyboards using the principles of ferrite memory and fixed transformer memory. The principle of the invention is that the core of the switching and coding element is divided into two parts, one of which is movable and is mounted on a button of the respective feature. The cores pass through the excitation and sensing wires. In the rest position, the magnetic circuit of the cores is interrupted by an air gap, the excitation current is not enough to magnetize the cores and no voltage is induced in the sensing wires. Pressing one of the buttons closes the cores, decreases their magnetic resistance, and starts to magnetize them. Voltage is induced in the sensing wires passing through the core. The number of sensing wires is determined by the code used, the wires pass through the core or pass by the required logical bit level of the character. In order to prevent incorrect code being generated when several buttons are pressed, the locking wire passes through all cores except for a few function buttons.

The principle is shown in the attached drawing.

Core with rectangular hystereznl curve consists of a movable part I fixed portion 2 through which the excitation conductor 2 $ n sensing wires and a locking wire J. core in the active position is remagnetization alternating excitation pulses through conductor 2 ® in the sensor conductor 4 ^is induced voltage adapted to the desired logic level for generating the code of the character 8. The blocking conductor 2 prevents the generation of an incorrect code when a plurality of buttons are pressed and the output J of the release signal, i.e., the button, is derived therefrom.

Claims (1)

Inductive proximity keypad, characterized in that its ferromagnetic switch-encoders become split cores, the movable parts of which I1 | are fixed to the keys and their fixed parts passes the driver wire | 3 |, the sensor wires of the code | 4 | and a blocking conductor | 5 |, the conductors | 4 | and | 5 | are connected to the output circuit | 6 | to generate character code | 81 for output | 7 | and a release signal.