GB2139385A - Self annunciator - Google Patents

Abstract

An apparatus to assist people to locate articles which are not immediately discernible to the eye. It comprises a self-contained device adapted to be secured to or incorporated into an article to be located (such as a set of keys) which emits an output signal in response to an audible triggering signal. The triggering signal is one able to be produced by a person without mechanical or electrical aid.

Description

SPECIFICATION Self annunciator This invention was devised primarily to assist people to locate articles which are not immediately discernible by eye.

In other applications however, it may be used to identify a control element or the like for the assistance of a person called upon to operate that element.

As an instance of the first-mentioned aim one can point to the commonplace situation in which a person is temporarily unable to find some small article which he requires, which he knows to be nearby but which has been misplaced or is obscured from view by other articles.

Typically, one may instance a bunch of keys in the pocket of a jacket which has been laid aside or a spectacle case in a crowded desk drawer. It is annoying, and may be very time-consuming, to have to search around for such an article and the present invention facilitates its location. As an instance of the second mentioned field of application of the invention one may instance a machine having an emergency stop button which may be ona of a number of control buttons and which may be required to be identified immediately by a novice operator of the machine.

In all of the situations indicated above, there is one thing in common, namely, that the person looking for the article or seeking to identify an item is thrown upon his own resources so that any means to assist him must be operable without need of additional artificial aids.

Thus, the present invention consists in a self-annunciator adapted to be secured to or incorporated into an article to be located and which emits an output signal in response to an audible triggering signal which is able to be produced by a person without mechanical or electrical aid.

For preference the annunciator responds only to triggering signals within a predetermined narrow frequency band of the audio range. In that event, the chosen band is preferably one that may be produced by a person for example by whistling.

As applied to the location of hidden articles self-annunciators according to the invention emit an audible output signal and, for preference, the output signal is outside the predetermined frequency range of the triggering signal to avoid acoustic feedback. In applications of the invention to the identification of control items or sites the output signal may be a visual signal from a lamp. In either event, the output signal preferably continues for some time after the cessation of the triggering signal.

Thus, assuming an annunciator according to the invention has been secured to a bunch of keys, if a person wishes to know if the keys are in his bedroom he has only to enter the room and issue a brief whistle to be rewarded for example by a "beep" if the keys are present.

Perhaps he may have to repeat the performance to finally locate the keys.

As another instance, if a person wishes to locate the ignition switch of a car at night a brief whistle will cause a light to appear adjacent the ignition switch if the switch incorporates an annunciator according to the invention having such an output signal.

Whereas it is preferred for annunciators according to the invention to respond to a human whistle the invention may also extend to annunciators operating in response to audio triggering signals produced in other ways, for example by a clap of the hands.

One possible embodiment of the invention may comprise a generally cylindrical bullet-shaped casing having an eye at one end to enable it to be secured to a keyring and by such a ring to another article. The other end of the body may be closed by a removable, preferably screw end cap to form a battery compartment adapted to house one or more high power, low volume cells, for example so-called mercury cells.

Housed within the body is an input transducer, such as an electret microphone, to convert received sound into a corresponding audio frequency electric signal, a circuit means preferably in the form of an integrated circuit chip and an output transducer able to receive an electrical signal from the circuit means and emit an audio tone. Both the input transducer and output transducer are preferably mounted adjacent apertures in the casing to facilitate the passage of sound therethrough. The circuit means interconnects to the input and output transducers and also to the power cell or cells. It may comprise for example a band pass amplifier fed from the input transducer in association with a filter network to produce a pass band response by the amplifier within the range of the human whistle.The output from the amplifier is fed into a detector circuit which, in turn, controls an electronic switch having two positions, one in which the voltage from the power cell is applied to a capacitor for the charging thereof and another in which the capacitor is allowed to discharge through the output transducer, in this instance a buzzer.

Preferably, an on/off switch is also provided to allow the user to turn the annunciator off when not required, for example, immediately prior to pocketing a bunch of keys to which the annunciator is linked. One suitable form of on/off switch may be a rotary switch operable by a ring encircling the body of the annunciator.

The presently preferred embodiment of the invention is shown in more detail in the attached drawings in which: Figures 1, 2 and 3 are cross-sectional views of one form of "self annunciator" according to this invention, Figures 4, 5 and 6 are schematic block diagrams of one preferred form of circuit means, Figure 7 is a circuit diagram of the aforementioned circuit means.

The case 1AA for the device is of cylindrical shape and may be for example 62mm long and 15mum in diameter.

One end 2AA of the cylinder is tapered 18 with a mounting for attachment of a metal split ring.

The other end of the cylinder has a removable end cap 3AA for battery access.

The end cap 3AA rotates in a 40 arc and is fitted with contacts to form a rotary on/off switch.

The case 1AA is preferably injection moulded from polycarbonate or similar durable plastic.

The electronic circuit 4AA for the device would preferably be constructed of commercially available components and is housed immediately forward of the batteries 5AA. It is comprised of three sections: input transducer 6AA; the output transducer 7AA; and integrated circuit 8AA.

The input transducer may consist of a miniature condenser microphone insert, having the function of detecting acoustic sound waves from a human whistle and converting this into electrical energy.

It is desirable that the greatest sensitivity of the microphone lie in the band between 660Hz 8 1980Hz.

Preferably the microphone response curve should fall rapidly outside this band, to reduce the possibility of the device operating on unwanted signals and the amount of signal processing required.

The output transducer 7AA may be a miniature sound source of a known type such as those used in computerized cash registers and digital alarm clocks. It gives a high output 3.3 KHz tone to provide an acoustic alarm.

Hardware necessary for the construction of the device includes: i) Battery contacts; ii) Switch contacts; and iii) Attachment ring.

There are two battery contacts 9AA in the device.

One contact is fitted into the removable end cap and may be made of plated strip metal (e.g.

Phosphor Bronze).

This contact also forms one half of the switch contact on the lip of the end cap 3AA.

The other battery contact is fitted into a barrier 1 OAA half way down the inside of the body of the case. This contact may also be constructed of plated strip metal or nickel plate steel wire in a spiral spring form.

There are two switch contacts 1 1AA for on/off control. One may be on the rim of the removable end cap and forms part of the battery contact. The other 1 2A may comprise a plated wire running down the inside edge of the battery compartment and retained within recesses in the moulding. It extends from the outer rim of the end cap into the compartment housing the electronics and is formed to engage with the flat contact in the end cap. The on/off action is obtained by rotating the end cap 3A.

The Intergrated Circuit 8AA is preferably a dedicated, micropower, monolithic design. The function of this circuit is to accept the electrical energy from the input transducer 6AA, process this information and provide the output transducer 7AA with a tone signal to give an audible alarm in response to a pre-determined acoustic signal such as a human whistle. The energy supply for the circuit may be 2 or 4 1.5 volt Silver Oxide (Ag2o) primary cells 5 commonly known as Type S76 and used in calculator and photographic equipment.

The preferred form of integrated circuit may be connected in one of two ways, as shown in Figs. 4 and 5. A block diagram of this integrated circuit is also shown in Fig. 6.

Referring first to Figs. 4 and 5 a power supply connected between Terminal 1 and Terminal 2 is required for the operation of the circuit. The positive end of the supply should be connected to Terminal 1 and the negative end to Terminal 2. The power supply may be primary or secondary cells or a voltage derived from a remote source and preferably be within the range of 2.4V to 7.0V. The current drain in such circumstances should be less than 50uA.

The frequency set network comprising a resistor and capacitor connected between Terminal 3 and Terminal 4, is common to both methods of using the integrated circuit. This network should be stable for consistant operation of the integrated circuit.

In Fig. 4 the input transducer 6AA is connected between Terminal 5 and Terminal 2 and the output transducer 7AA is connected between Terminal 6 and Terminal 7.

As shown in Fig. 5 the input and output transducer 6AA and 7AA may be the same device.

In this case the optimum dual purpose transducer is a piezoelectric disk.

Refering now to Fig. 6 the power supply is for distribution of the applied voltage, and its return. Preferably there is no internal regulation for this integrated circuit.

The operation of the integrated circuit depends essentially on the frequency of the oscillator and subsequently the output from the two oscillator dividers.

The microphone output 5 is amplified at 8 and with an output from the oscillator 9 a pulse is generated for each positive transition of the microphone voltage.

The incoming signal period is resolved by counting the number of oscillator clocks between pulses from the amplifier and a pulse shaper. The contents of the period resolver 10 can be loaded into a period register 11 and the two checked for equality by the period comparator 1 2.

When the output time divider 1 3 has counted to a predetermined maximum and the input signal is outside limits the control logic 14 enters an idle state in which the output is disabled and the microphone input 5 is active. Whenever the amplifier and pulse shaper 8 output is active the control logic checks the count in the period resolver, if it is within limits, for the first time after the idle state, the contents are loaded into the period register. This is the transition state between the idle state and the tone output state. The duration of the transition state is determined by the contents of the on-tone counter 1 5.

For each subsequent output from the amplifier and pulse shaper 8 the period measured by the period resolver 10 is checked against the contents of the period register 11. If these are equal for sixty four consecutive periods, as measured by the on-tone counter 15, the integrated circuit enters the tone output state.

If, during the transition state, the input signal is outside limits the circuit returns to the idle state. The transition state is recommenced if the contents of the period register 11 and the period resolver 10 are not equal.

For the duration of the tone output state the amplifier and pulse shaper output is disabled.

The tone divider 16 is enabled by the tone output state as is the output buffer 1 7. The output buffer 1 7 is gated with an output from the output time divider 1 3 to produce several bursts of tone.

The duration of the tone output state is determined by the output time divider 1 3 which when the terminal count is reached resets the circuit into the idle state.

Because the period register 11 and period comparator 1 2 have a resolution of two bits there are four values possible. With the uncertainty of digitising the period of an incoming waveform there are four bands to which the circuit will respond.

When the oscillator is set to 52.8KHz the circuit will have the following characteristics.

Input response: Band one-is 825Hz to 942.9Hz Band two-is 942.9Hz to 1100Hz Band threewis 1100Hz to 1320Hz Bandfouris 1320Hz to 1650Hz Minimum duration: at 825Hz-is 77.6mS at 1650Hz--is 38.8mS Output tone is:-3.3KHz Output duration is:--1.24 seconds Any change in the oscillator 9 will change the above operational parameters.

Referring now to Fig. 7 the three sections of A2 form an oscillator running at 52.8HKz which is a period of 18.94 micro-seconds. The two sections of A3 are a divide by four ripple counter with an output at A3P13 of 13.2 kilo-hertz which is a period of 75.76 micro-seconds.

The output from the microphone is amplified by A41 and Al 3 which have a gain of 47 each.

The bandwidth of this pair of amplifiers is limited at the low frequency end by the three coupling capacitors and at the high frequency end by the slew rate of the LM4250 operational amplifiers. The three sections of Al 5 form a "schmitt" trigger and ensure a full logic swing for small input signals from the microphone. The two sections of Al 6 with part of Al 9 form a pulse shaping network such that at A16 P13 a pulse is generated with a positive duration of the oscillator signal on A16 P11 and a repetition rate equal to the signal on A16 P3 derived from the microphone output.

The oscillator output A3 P13 is fed into the period resolver which is a four stage ripple counter with an overflow stage. The clock inputs are A4 P3, A4 P11, A5 P3, A5 P11 and A6 P3 and ail share a common set signal which is the output from the amplifier and pulse shaper delayed by the two sections of A17. If the period between the common set pulses on the period resolver is within 8 to 16 counts of the oscillator at A3 P13 then A5 P13 and A6 P2 will be low. This will occur when the microphone input is between 825Hz and 1650Hz. A6 P1 -6 is the overflow stage and once clocked A6 P2 will go high until set low at the end of the measurement time.

The idle state is when A18 P1 is low which keeps the transition state flip-flop (A18 P9-13) reset. When A8 P6 goes high, indicating that the microphone is within 825Hz to 1650Hz, A18 P1 goes high loading the three least significant bits of the period resolver into the period register. Only the two most significant bits (A7 P5 and A7 P9) are active as the first stage A6 P9-13 and its comparator output at A9 P3 is unconnected.

The period comparator is implemented using two exclusive "or" gates and A8 P10-13.

During the transition state A18 PlO is low and A18 P12 will be low as long as the period comparator indicates the input period and stored period are identical within the resolving power of the circuit.

If during the transition state the microphone output is outside the 825Hz to 1650Hz limits A8 P6 will go low and force the control logic into the idle state. The two sections of A3 1, A32 and A33 form a six stage ripple counter which is the on-tone counter. This counter chain is set to zero count whenever the period comparator output at AP8P10 goes low indicating the stored count and current count are not equal.

When the on-tone counter reaches a count of 64,A20 P3 is clocked and the tone output state is entered. The amplifier output is inhibited by A2O P1 at Al 5 P3 s 5.A20 5. A20 P2 is low during the tone output state and the oscillator signal from A3 P1 3 is passed by A19 P6 to A34 P3.

The tone divider drives the output buffer (Al 0) and the output time divider from A34P13.

The output buffer at A10 P6 e 10 is tri-stated by A20 P1 or 2 during the idle state so that one transducer may be used for microphone and loudspeaker. The output buffer is also gated by a flip-flop in the output time divider to produce 8 bursts of tone during the 1.24 seconds of output.

The output time divider is a 1 2 stage ripple counter that counts 4096 cycles of the 3.3KHz output and then clocks A20 P1 1. A pulse at A20 P13 resets A20 P4 and terminates the tone output state and the circuit returns to the idle state.

it will thus be appreciated that this invention at least in the form of the embodiment disclosed provides a novel, unique and extremely useful device for locating misplaced articles. Clearly however the particular example described is only one possible form of this invention and a wide variety of modifications apparent to a man skilled in the art may be made to the shape and configuration of the housing and/or the circuitry to adapt the concept to any particular application.

Claims (11)

1. A self-annunciator adapted to be secured to or incorporated into an article to be located and which emits an output signal in response to an audio triggering signal which is able to be produced by a person without mechanical or electrical aid.

2. The self annunciator as claimed in claim 1 wherein said audio triggering signal is within a predetermined frequency range above the normal voice range.

3. The self annunciator as claimed in claim 2 wherein said audio triggering signal is comprised by said person whistling.

4. The self annunciator as claimed in claim 2 or 3 wherein said output signal comprises an audible output signal which is outside said predetermined frequency range of said triggering signal so as to avoid acoustic feedback.

5. The self annunciator as claimed in claim 1 or 2 wherein said output signal comprises a visual signal from a lamp.

6. The self annunciator as claimed in any one of the preceding claims wherein the output signal continues for some time after cessation of the triggering signal.

7. The self annunciator as claimed in any one of the preceeding claims wherein said annunciator comprises an input transducer adapted to receive and convert the triggering signal into a first electrical signal, a circuit means adapted to process said first electrical signal, and an output transducer adapted to emit the output signal upon receiving a second electrical signal from the circuit means.

8. The self annunciator as claimed in claim 7 wherein the input and output transducers are both comprised by one device such as a piezoelectric disk.

9. The self annunciator as claimed in claim 7 or 8 wherein said circuit means comprises a band pass amplifier fed from the input transducer in association with a filter network to produce a band pass output response when actuated by said predetermined range of said triggering signal and said output response is fed into a detector circuit which controls an electronic switch to enable an oscillator and output buffer through the output transducer to produce the output signal.

10. The self annunciator as claimed in claim 7 or 8 wherein said circuit means comprises an integrated circuit chip.

11. The self annunciator as claimed in claim 10 wherein the circuit means is a dedicated micropower monolethic design substantially as described herein with reference to Figs. 4 to 7.