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Publication numberWO1991017634 A1
Publication typeApplication
Application numberPCT/US1991/003019
Publication date14 Nov 1991
Filing date2 May 1991
Priority date4 May 1990
Publication numberPCT/1991/3019, PCT/US/1991/003019, PCT/US/1991/03019, PCT/US/91/003019, PCT/US/91/03019, PCT/US1991/003019, PCT/US1991/03019, PCT/US1991003019, PCT/US199103019, PCT/US91/003019, PCT/US91/03019, PCT/US91003019, PCT/US9103019, WO 1991/017634 A1, WO 1991017634 A1, WO 1991017634A1, WO 9117634 A1, WO 9117634A1, WO-A1-1991017634, WO-A1-9117634, WO1991/017634A1, WO1991017634 A1, WO1991017634A1, WO9117634 A1, WO9117634A1
InventorsSeabourn Livingstone, Robert S. Patti, Michael K. Pedigo
ApplicantSeabourn Livingstone, Patti Robert S, Pedigo Michael K
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Transmitter/receiver system for locating misplaced objects
WO 1991017634 A1
Abstract
There is provided a transmitter/receiver system for locating a misplaced object, such as eyeglasses (34), which includes a transmitter unit (10) which generates a signal when energized by power means such as a battery (20) and switch of a flashlight (26) and a receiver unit (30) on or disposed in the frame of the eyeglasses (34) having an antenna (36) responsive to the signal of the transmitter, a detector (38) and an electronic switch means (40) which changes state between an on status and an off status and which comprises a capacitor and a signal device coupled to an alarm oscillator (43) which is energized when the change occurs and when the capacitor discharges, thereby emitting an audible tone which attracts the user to the location of the eyeglasses (34). The receiver unit (30) is powered by means comprising a low frequency oscillator (46) which is continuously oscillating to intermittently power the receiver unit (30) and thereby save energy.
Claims  (OCR text may contain errors)
WE CLAIM:
1. A transmitter/receiver system for locating a misplaced object comprising: a transmitter unit having means for generating a signal at a RF carrier frequency, means for modulating said signal at a first audio frequency coupled to a first antenna, and first power means to power said transmitter unit; and a receiver unit adapted to be placed on an object to be located having a second antenna responsive to said RF carrier frequency, a detector coupled to said second antenna, electronic switch means coupled to said detector which changes state upon detection of the modulation frequency, audio means on said object coupled to said switch means to be energized when said change occurs thereby attracting the attention of a user, and second power means coupled to a low frequency electronic oscillator having a continuous sawtooth waveform applied to said second power means to intermittently power said receiver unit, such that power is applied over time to said receiver unit at a leading edge of each pulse in said waveform and rapidly terminated at a trailing edge of each said pulse. 2.
1 The device according to claim 1 wherein said
2 switch means is responsive to said detector for •-* intermittently operating said audio means when amplitude
4 of said first audio frequency at said detector is weak,
5 and is responsive to said detector for continuously
6 operating said audio means when amplitude of said first
7 audio frequency at said detector is strong.
3.
1 The device of claim 1 wherein said first power
2 means comprises a battery of a flashlight, a light and a
3 switch of a flashlight, said transmitter being energized
4 by said battery when said switch is closed, and wherein *** said receiver unit comprises a substrate having an area
6 less than about 6.5 square centimeters.
4. The device of claim 1 wherein said RF carrier is modulated at a frequency in the range of 2 to 3 khz.
5. The device of claim 1 wherein said low frequency oscillator has a period in the range of one to one and one half seconds and a duty cycle of about 2 to 3 percent.
6.
1 The device of claim 1 wherein said means
2 responsive to said change is a signal device which emits
3 an audible tone which is about 3 khz.
7.
1 The device of claim 6 wherein said means
2 responsive to said change comprises an alarm oscillator •*** coupled to said signal device.
8.
1 The device of claim 7 wherein said electronic
2 switch comprises a capacitor which discharges when said
3 modulation signal is received causing said alarm oscillator
4 to oscillate.
9.
1 The device of claim 3 wherein said substrate is
2 attached to a frame of eyeglasses.
10.
1 The device of claim 3 wherein said substrate is
2 disposed in a recess in the frame of eyeglasses.
11. A transmitter/receiver system for locating eyeglasses comprising: a transmitter unit which generates a first signal which is in the range of 2 to 3 khz, when energized by first power means comprising a battery and switch of a flashlight, said transmitter being energized by said battery when said switch is closed; a receiver unit of said eyeglasses having an antenna responsive to said first signal, a detector coupled to said antenna and an electronic switch means coupled to said detector which changes state between an on status and an off status and which comprises a capacitor, a signal device coupled to an alarm oscillator which is energized when said change occurs and when said capacitor discharges, which emits an audible tone which is about 3 khz, thereby attracting the user to the location of said eyeglasses, and second power means comprising a low frequency electronic oscillator having a continuous sawtooth waveform applied to said second power means to intermittently power said receiver unit, such that power is applied over time to said receiver unit at a leading edge of each pulse in said waveform and rapidly terminated at a trailing edge of each said pulse.
Description  (OCR text may contain errors)

Title: TRANSMITTER/RECEIVER SYSTEM FOR LOCATING MISPLACED OBJECTS

This invention relates to a transmitter/receiver system for locating a misplaced object such as eyeglasses.

Background and Summary of the Invention

Devices for locating misplaced objects are known, and commonly include a transmitter which emits a first tone which is responded to by a receiver on the object. The receiver unit commonly includes a tone generator which emits a second tone. The second tone attracts the attention of the user who then follows the tone to locate the object.

An object of the instant invention is to provide a receiver unit, for use in a system of the subject character, which conserves power by means of an electronic oscillator which functions as an electronic switch, intermittently applying power to the receiver unit; and which has a miniaturized receiver which is able to be attached conveniently to the frame of eyeglasses.

The advantages are that power is conserved at the receiver so that the battery which powers the receiver unit has an extended life; and the receiver unit may be very small with no moving parts as would be required in a mechanical switch. Brief Description of the Drawings

Fig. 1 is a block diagram of a transmitter unit. Fig. 2 is a block diagram of a receiver unit. Fig.3 is a schematic of the transmitter of Fig.1. Fig. 4 is a schematic of the receiver unit of

Fig. 2.

Fig.5a shows a perspective view of a transmitter unit in a flashlight.

Fig. 5b shows a perspective view of a receiver unit in the eyeglasses frame.

Detailed Description of the Preferred Embodiments

Referring to Figs. 1 and 3, there is shown a transmitter unit 10 which includes RF oscillator 12 and audio oscillator 14 which generate a signal at a first audio frequency. A modulator 16 combines the signals from oscillators 12, 14 to form an amplitude modulated RF signal that is fed to a first antenna 18. A first battery 20 energizes RF oscillator 12, audio oscillator 14 and modulator 16. Preferably, transmitter unit 10 is disposed between the light 22 and the battery 20 of a flashlight 26, as shown in Fig. 5. Transmitter unit 10 is thus energized by battery 20 when switch 28 of flashlight 26 is closed.

Receiver unit 30 (Figs. 2, 4 and 5) is disposed on a substrate 32 which is adapted to be attached to or disposed in an object such as eyeglasses frames 34. The receiver unit 30 has a second antenna 36 responsive to the RF carrier frequency, and a detector 38 coupled to second antenna 36. An electronic switch 40 is coupled to detector 38 through a filter 41. Switch 40 changes state, that is, changes between an on and an off status, upon detection of the modulation frequency at detector 38. A signal device 42, coupled to the electronic switch 40, is responsive to the change of state, and is energized by an alarm oscillator 43 when such change occurs. Signal device 42 attracts the attention of the user and may be audible or visual. Preferably, signal device 42 is an audio buzzer, and an audible signal is generated at about 3 khz.

Receiver unit 30 has a second battery 44 and a voltage regulator 45 which energizes detector 38, electronic switch 40, signal device 42 and alarm oscillator 43. Preferably, the RF portion of receiver unit 30 - i.e., detector 38, switch 40 and filter 41, - has an input power bus 47 operated by a low frequency oscillator 46 which intermittently applies power to the receiver unit 30. Preferably, low frequency oscillator 46 has a period in the range of one to one and one half seconds, and a duty cycle of about 2 to 3 percent. Low frequency oscillator 46 is an electronic oscillator which acts as a switch. The output waveform 46a of oscillator 46 is of a sawtooth configuration, as shown in Fig. 4. That is, the leading edge 46b of each pulse is sloped, so as to apply power gradually to the remainder of the receiver circuitry. On the other hand, the trailing edge 46c of each pulse is abrupt or steep, for quickly removing power from the circuit. The gradual power application provided by edges 46b prevent generation of noise and spikes in the detector circuitry, which could have an amplitude greater than the amplitude of the signal being detected at detector 38. The leading edges 46b generate a small spectrum of harmonics ringing in the receiver, and prevent false triggering of audio buzzer 42. Thus, the slow power-up prevents circuit instabilities and also has a very small spectrum of harmonics generated by the rising edge slope.

As shown in Fig. 4, switch 40 comprises a transistor 50 having a base connected to filters 41 and emitters connected to ground, and a collector connected to the enable input of oscillator 43. A capacitor 51 is connected across the collector and emitters of transistor 50, and a resistor 52 connects the collector of transistor 50 to the output of voltage regulator 45. Resistor 52 has high resistance, such as one megohm, and capacitor 51 has high capacitance, such as 0.33 microfarad. Thus, capacitor 51 is charged relatively slowly through resistor 52. When transistor 50 turns on, upon detection of the modulating signal at filter 41, capacitor 51 rapidly discharges, and the enable input of oscillator 43 is brought low. Oscillator operation is thereby enabled. When power is thereafter removed from detector 36 and filters 41, transistor switch 50 opens, and capacitor 51 begins to charge. However, the charge time of capacitor 51 through resistor 52 is such that oscillator 43 will continue operation - i.e., not be disabled - before oscillator 46 again applies power to bus 47. Thus capacitor 51 and resistor 52 are selected so that capacitor 51 does not interfere with the oscillation of alarm oscillator 43 during the time the modulating signal is being received. In accordance with another feature of the invention, the buzzer 42 is energized as a function of distance from the transmitter to the receiver. That is, when the transmitter is relatively far from the receiver, the amplitude of the modulating signal at detector 38 and filter 41 is relatively weak. Capacitor 51 does not fully discharge when transistor so is turned on. Capacitor 51 has an opportunity to charge fully before the next pulse of waveform 46a. Oscillator 43 is therefore intermittently enabled, and buzzer 42 is intermittently energized. On the other hand, when the transmitter is close to the receiver, and the detected audio modulating signal is strong, capacitor 51 is fully discharged upon occurrence of each pulse in waveform 46a, and does not fully discharge between pulses. Buzzer 42 is thusly continuously energized.

In the preferred embodiment the instant invention comprising elements set forth immediately below, is used to locate misplaced eyeglasses 34. The invention comprises a transmitter unit 10 which generates a first signal in the range of 2 to 3 khz. Transmitter unit 10 is disposed between a light 22 and a battery 20 in a flashlight 26. The transmitter unit 10 is energized when the switch 28 of the flashlight 26 is closed.

A receiver unit 30 is made small enough so as to be able to be disposed on a substrate 32 with an area of about .5 to 1.5 square inches (about 3 square centimeters to about 10 square centimeters), and preferably with an area of less than one square inch (about 6.5 square centimeters). The receiver unit 30 is attached to eyeglasses frame 34 or disposed in a recess 60 of eyeglasses frame 34 and has a second antenna 36 responsive to the RF signal, a detector 38 coupled to said second antenna 36, an electronic switch 40 coupled to the detector 38 which changes state between an on status and an off status, and signal device 42 which emits an audible tone which is about 3 khz. Therefore, in the preferred embodiment, the 3 khz tone is emitted from the eyeglasses 34 when the change occurs, thereby attracting the attention of a user. The receiver unit 30 has a second battery 44, voltage regulator 45 and a low frequency oscillator 46 which is continuously oscillating to intermittently power the receiver unit 30. The low frequency oscillator 46 has a period in the range of one to one and one half seconds and a duty cycle of about 2 to 3 percent.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
JPH01141498A * Title not available
JPH01183298A * Title not available
JPS63172985A * Title not available
JPS63314994A * Title not available
US4101873 *26 Jan 197618 Jul 1978Benjamin Ernest AndersonDevice to locate commonly misplaced objects
US4476469 *13 Nov 19819 Oct 1984Lander David RMeans for assisting in locating an object
US4507653 *28 Jun 198426 Mar 1985Bayer Edward BElectronic sound detecting unit for locating missing articles
US4523332 *11 Apr 198311 Jun 1985Nec CorporationBattery saver circuit for use with paging receiver
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5506717 *28 Feb 19949 Apr 1996Goldstar Co., Ltd.Apparatus for locating a remote control transmitter
US5945918 *21 Dec 199431 Aug 1999Mark G. McGonigalApparatus and method for locating a remote control unit
US5952918 *20 Nov 199714 Sep 1999Ohayon; ShalomRecovery mode feature for remote units
Classifications
International ClassificationG08B21/24
Cooperative ClassificationG08B21/24, G08B21/023
European ClassificationG08B21/02A7, G08B21/24
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