Coded data generation or conversion – Bodily actuated code generator – Including keyboard or keypad
Reexamination Certificate
1999-12-13
2001-02-06
Horabik, Michael (Department: 2735)
Coded data generation or conversion
Bodily actuated code generator
Including keyboard or keypad
C341S020000, C341S022000, C340S870030
Reexamination Certificate
active
06184805
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a keyboard encoding method and device for application in such apparatus as portable radiotelephones and calculators for instance. More specifically, the present invention relates to a device for detecting unambiguously which key of a number of keyboard keys or buttons has been actuated.
DESCRIPTION OF THE BACKGROUND ART
Such a keyboard encoding device is taught by U.S. Pat. No. 4,725,816. When a given key is actuated resistances are mutually coupled so as to generate, together with a current source, a d.c. voltage that is. unique to the actuated key. An A/D converter converts the unique d.c. voltage to a digital signal. One problem with this solution is that the A/D converter is a relatively expensive and complicated component. Another problem is that the A/D converter is difficult/expensive td integrate in the same silicon chip as the remaining digital circuits.
A device that is very similar to the device described in U.S. Pat. No. 4,725,816 is designed to mutually couple resistances when a given key is actuated, such that said coupled resistances will form with a voltage source a voltage divider that delivers a unique d.c. voltage corresponding to the actuated key. An A/D converter converts the unique d.c. voltage to a digital signal. The above-mentioned problem encountered with the solution taught by U.S. Pat. No. 4,725,816 also applies to this solution. U.S. Pat. No. 4,327,255 teaches a signal generating device for a telephone keypad. Actuation of a key results in the generation of a signal that consists of two sinusoidal signals of different frequencies (Dual Tone Multi Frequency, DTMF). This known device, however, functions to generate a multi-frequency signal that corresponds to a given key and that is sent, for instance, to a telephone exchange for the purpose of identifying one of a number of numbers in a subscriber identity.
U.S. Pat. No. 4,315,108 teaches a DTMF signal generating device which is implemented in one single integrated circuit.
U.S. Pat. No. 3,949,639 teaches an electronic musical instrument provided with a keyboard. Actuation of a key generates a signal of given voltage which controls an oscillator to produce a tone of given frequency.
U.S. Pat. No. 4,412,209 describes a device which in response to activation of one of a number of switches produces a unique combination of resistances and capacitances that can be detected by an external circuit connected to the device and therewith determine which key has been actuated.
SUMMARY OF THE INVENTION
In respect of an apparatus that is equipped with a number of keys, the present invention addresses the problem of detecting which of the keys has been actuated in response to actuation of said key.
Accordingly, one object of the present invention is to provide a solution to the problem of detecting unambiguously which key of said number of keys has been actuated, with the aid of inexpensive electronic circuits to this end.
The aforesaid problem is solved generally by the invention with the aid of a method and a device in which one or more oscillating signals is/are generated in response to actuation of one of the keys, and the identity of the actuated key is is determined from these signals.
More specifically, the invention solves the aforesaid problem by generating in response to the actuation of a given key at least one oscillating signal whose character corresponds unambiguously with the actuated key.
According to one embodiment of the invention, it is the frequency of the oscillating signal that corresponds unambiguously to the actuated key.
According to another embodiment of the invention, it is the pulse ratio (relative pulse duration) of the oscillating signal that corresponds unambiguously to the actuated key.
According to a further embodiment of the invention, there are generated two oscillating signals whose frequency difference corresponds unambiguously to the actuated key.
In all embodiments of the invention, there is determined from the signals generated a value which indicates unambiguously the key that has been actuated.
One advantage of the invention is that it can be implemented with the aid of simpler and less expensive circuits, or circuit units, than was possible with earlier known devices of this kind.
Another advantage is that certain embodiments of the invention provide improved protection against erroneous detection arising from variations in the temperature or humidity of the apparatus surroundings, for instance.
The invention will now be described in more detail with reference to preferred embodiments thereof and also with reference to the accompanying drawings.
REFERENCES:
patent: 3715745 (1973-02-01), Arciprete
patent: 3778815 (1973-12-01), Wright
patent: 3949639 (1976-04-01), Adachi
patent: 4146849 (1979-03-01), Satou
patent: 4315108 (1982-02-01), Hoffman et al.
patent: 4327255 (1982-04-01), Suszylo
patent: 4412209 (1983-10-01), Frame et al.
patent: 4725816 (1988-02-01), Petterson
patent: 4727570 (1988-02-01), Tarbouriech
patent: 1 402 162 (1975-08-01), None
patent: 2 291762 (1996-01-01), None
Analog Devices, “Low Cost Monolithic Voltage-to-Frequency Converter”, AD654, Rev. A, One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106.
Burns, Doane, Swecker & Mahthis, L.L.P.
Horabik Michael
Telefonaktiebolaget LM Ericsson (publ)
Wong Albert K.
LandOfFree
Apparatus and a method for keyboard encoding does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and a method for keyboard encoding, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and a method for keyboard encoding will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2609132