Alarm shut-off device, with a wake up signal delivering integrated circuit and a receiving and signal shaping network

• US 4,894,813 A
• Filed: 05/26/1988
• Issued: 01/16/1990
• Est. Priority Date: 06/06/1987
• Status: Expired due to Fees

• Current Assignee: Braun Aktiengesellschaft
• Original Assignee: Braun Aktiengesellschaft
• Inventors: Pacher, Lothar, Schiebelhuth, Heinz
• Primary Examiner(s): Roskoski, Bernard
• Application Number:
  US07/199,155
• Time in Patent Office: 600 Days
• Field of Search: 368/72, 368/73, 368/243-266
• US Class Current: 368/256
• CPC Class Codes: G04G 13/021 Details

Abstract

The invention is directed to an alarm shut-off device for an alarm clock or timer permitting a signal delivered by the clock to be interupted or to be cancelled in that the user of the clock approaches the clock or merely moves a part of his body, for example, his hand, towards the clock. Preferably, the clock is equipped with a transmitter 2, 2'"'"' emitting infrared radiation or ultrasonic waves and a corresponding receiver 3, 3'"'"' which detects the infrared radiation or the ultasonic waves reflected by the moved body part 1. A signal shaping network 4, 5 and 6 determines the variation of the intensity with time, which variation is compared in a threshold switching stage 7 with a predeterminable value which, when exceeded, causes the alarm signal A to be shut off.

Claims

1. An alarm shut-off device, in particular for an alarm clock or timer, with a clockwork containing an integrated circuit which, when the clock time matches the alarm time, delivers a wake-up signal to a signal generator preferably configured as an electroacoustic transducer, with a receiving and signal shaping network which includes a receiver sensitive to radiation a filter amplifier, and a threshold switching stage for receiving and further processing a shut-off signal issued by the user of the clock, means responsive to said wake-up signal for connecting said receiving and signal shaping network to its voltage supply following which said receiving and signal shaping network processes said shut-off signal such that its application to an input of said integrated circuit causes said circuit to interrupt the delivery of said wake-up signal,

said receiving and signal shaping network further including a rectifier and differentiator stage, said rectifier and differentiator stage including rectifier circuitry and a differentiator connected subsequent to said rectifier circuitry, the output signal of said differentiator being determined by the variation with time of the radiation detected by said receiver.

2. An alarm shut-off device as claimed in claim 1 wherein said device includes a radiation emitting transmitter, the radiation emitted by said transmitter being reflected by the user of the device and detached by said receiver.

3. An alarm shut-off device as claimed in claim 1 wherein between the output of said threshold switching stage and the input of said integrated circuit a one-shot multivibrator is connected the output of multivibrator being connected to the input of said integrated circuit and said multivibrator being caused to assume its astable state when an ouput signal (H) occurs at the output of said threshold switching stage which is connected to the input of said Multivibrator.

4. An alarm shut-off device as claimed in claim 3 wherein said rectifier and differentiator stage includes two series-connected assemblies of which the assembly acting as a rectifier is comprised of a voltage-doubling circuit including two diodes and two capacitors, while the assembly acting as a differentiator is comprised of a capacitor and a resistor connected to series.

5. An alarm shut-off device as claimed in claim 4 wherein said receiving and signal shaping network includes a signal delay stage arranged ahead of said threshold switching stage and serving to delay, following delivery of said wake up signal (A), its output signal (Q) relative to its input signal (P) for such a length of time (t3-t2) that the said signal generator issues an alarm signal (a) at least for a predeterminable time span (t3-t1).

6. An alarm shut-off device as claimed in claim 5 wherein said signal delay stage is connected in parallel with said rectifier and differentiator stage and includes an open-collector comparator, the output of which is connected to the output of the differentiator of said differentiator stage, and that the delay time (t3-t2) is determined by a capacitor and a resistor connected in series.

7. An alarm shut-off device as claimed in claim 6 wherein said threshold switching stage includes an comparator having applied to tis first input a reference voltage, its second input being connected both to the output (P) of said differentiator of said rectifier and differentiator stage and to the output (Q) of said comparator of said signal delay stage.

8. An alarm shut-off device as claimed in claim 3 wherein the wake-up signal (A), in addition to being applied to said signal generator, is further applied to a first input (B) of an ON-OFF control stage via a Zener diode and a diode connected in series, said control stage connecting, via a switching stage, both said receiving and signal shaping network and said transmitter to their respective supply voltages.

9. An alarm shut-off device as claimed in claim 8 wherein said ON-OFF control stage produces an ON signal from signal (B) present at the output of said diode by means of a Zener diode and a charging capacitor in parallel arrangement, said ON signal rendering an output transistor conducting with a predetermined time delay (t2-t1), said output transistor in turn causing a series transistor arranged in said switching stage to conduct.

10. An alarm shut-off device as claimed in claim 8 wherein the output signal (I) of said one-shot multivibrator is further applied through a turn-off element to a second input (L) of said ON-OFF control stage the ouput signal (C) of which disconnects said receiving and signal shaping network and said transmitter from their respective supply voltages via said switching stage after said one-shot multivibrator has switched to its astable state.

11. An alarm shut-off device as claimed in claim 10 wherein said turn-off element is comprised of a common-emitter transistor arranged in the base-emitter circuit of the ouput transistor of said ON-OFF control stage and having the output signal (I) of said one-shot multivibrator applied to its base.

12. An alarm shut-off device as claimed in claim 2 wherein said transmitter includes an infrared diode emitting infrared radiation in the pulse control mode, with the pulse recurrence frequency and the pulse duration being determined by the dimensional design of the capacitor and a resistor combining with two further resistors to form an astable multivibrator.

13. An alarm shut-off device as claimed in claim 12 wherein the pulse recurrence frequency of said transmitter is preferably in the range of 500 Hz in infrared operation.

14. An alarm shut-off device as claimed in claim 2 wherein said receiver includes an infraredsensitive diode which has its cathode connected to a voltage (N) derived from the battery voltage (U) and combines with a resistor to form a voltage divider to the tap of which a capacitor is connected supply the signals received from said diode to said filter amplifier.

15. An alarm shut off device as claimed in claim 2 wherein said receiver and said transmitter are relatively spaced on the upper edge of the front side of the clock housing, and that the main transmitting or receiving direction X of said transmitter or receiver signal is inclined upwardly relative to the horizontal Y by an angle of preferably between 20°

and 25°

.

16. An alarm shut-off device as claimed in claim 3 wherein the output signal (I) of said one-shot multivibrator is further applied to the input of a lamp driver, the output signal (K) of which differs from zero value as long as said one-shot multivibrator is in its astable state.

17. An alarm shut-off device as claimed in claim 2 wherein said receiver and said transmitter operate in the ultrasonic wave range and form a joint transmitting and receiving assembly including an astable multivibrator and receiving assembly including transistors, with an ultrasonic transducer forming a feedback element for generating an oscillatory response.

18. An alarm shut-off device as claimed in claim 17 wherein said ultrasonic transducer is connected via a decoupling resistor arranged in the emitter branch of said two transistors, to the ouput of said transmitting and receiving assembly, said decoupling resistor being connected in series with an emitter resistor.

19. An alarm shut-off device as claimed in claim 2 wherein said receiver and said transmitter operate in the ultrasonic wave range and form a joint transmitting and receiving assembly including as astable multivibrator with two transistors in complementary connection, an ultrasonic transducer is connected, in series with a resistor, in the emitter branch of a transistor at the output end and an emitter resistor is connected in parallel with said serially connected ultrasonic transducer and said resistor.

20. An alarm shut-off device as claimed in claim 19, wherein said resistor is a potentiometer.