TELEPHONE ACCESSORY

Abstract: A telephone call indicator apparatus, especially for use with a telephone installed within a vehicle, comprises electronic circuitry, (IC1-IC6) arranged to respond to the receipt of an incoming call and to generate a signal for supply to a loudspeaker (LS1) mounted, e.g. within the engine compartment to produce a sound resembling the ringing of a telephone so that a driver who has left his vehicle temporarily is alerted to the incoming call.

Description: TELEPHONE ACCESSORY The invention relates to an accessory for a telephone especially of the type fitted to vehicles such as cars, trucks or the like. An incoming call causes the telephone in the vehicle to ring (like an ordinary telephone) or a light may be energised. When the driver wishes to leave the vehicle temporarily he can first switch the telephone into an alert mode, if his telephone is fitted with such a feature, by which an incoming call will cause the horn of the vehicle to sound for say 20 seconds, which is considered enough time for the absent driver to return to the vehicle and answer the incoming call. In the UK, it is illegal to use the horn for this purpose and in addition, many vehicle burglar alarms cause the horn to sound, and this provides a further source of confusion. There is a need for a warning device for use with a telephone installed in a vehicle which can provide for an. absent vehicle user a warning signal which cannot be confused with any other warning signal, and which has been generated legally. The invention is based on the realisation that extra apparatus can be provided, which is arranged to cause a loudspeaker to emit a relatively loud noise which resembles that of a ringing telephone. According to one aspect of the invention there is provided a telephone call indicator apparatus comprising switch means responsive to receipt by a telephone of an incoming call; signal generator .means controlled by the switch means and operative on receipt of the incoming call by the telephone to generate an output signal; and an electro-acoustic transducer to which the output signal of the generator means is supplied and which in response thereto emits sounds simulating a ringing telephone. Preferably, the apparatus is mounted in a vehicle and is in circuit with a telephone also mounted in the vehicle. If tke telephone is fitted with a call alert facility, the switch means may comprise a transistor which is controlled eg, from a control line from the telephone. If the telephone is not fitted with such a facility, the switch means may comprise further circuitry arranged to sense the electrical power consumption of the telephone and to provide an indication signal indicative of the receipt of an incoming call in response to an increase in such consumption above a predetermined level. In such a case the further circuitry may comprise in combination a bi-stable device switchable from a first state to a second state upon an increase of the power consumption above the predetermined level, a bi-stable multivibrator arranged to emit a continuous square pulse output signal when the bi-stable device is switched to its second state, and a counter arranged to count the pulses emitted by the multivibrator and to provide said indication signal only for a predetermined number of pulses from the multivibrator. In a preferred feature, the circuitry provides the indication signal only when the increase in consumption has lasted for longer than a predetermined time interval so that the apparatus is not actuated by the regular telephone transmissions required to notify a telephone network point of the location of the vehicle telephone. Such transmissions are short bursts of 0.5 second signal every 15 minutes. The means is arranged so that such transmissions are ignored. Preferably the further circuitry includes means arranged to mute the sound from a radio, cassette player or the like installed within the vehicle, when the telephone rings and for the duration of the call. In another aspect the invention includes a vehicle including such apparatus. In order that the device may be better understood, it will now be described with reference to the accompanying diagrammatic drawings in which:- Figure 1 is a circuit diagram of apparatus according to one embodiment of the invention; Figure 2 is a schematic diagram of apparatus according to a further embodiment of the invention; Figure- 3 is a circuit diagram of part of the apparatus of Figure 2; and Figure 4 shows the wave forms at various parts in the apparatus and according to time. Referring to Figure 1 , a loudspeaker LS1 is in series with a transistor TR3 across a 127 D.C. supply, which may be derived from a vehicle battery. The loudspeaker LS1 may be mounted within the engine compartment of the vehicle. Transistor TR3 is connected to transistor TR2, which arrangement serves to amplify a signal from the signal generating means IC1 , IC2, IC3 and an associated resistor and capacitor network R1 , R2, R3, C1 , C2, C3. The vehicle may be a car, lorry, motor bike, or may be a boat, aeroplane and the like. More specifically, the signal generating means comprises three integrated circuits IC1 , IC2 and IC3. Integrated circuit IC3 is of a CMOS 4047 multivibrator type arranged to output a free-running square wave form or a train of logic 1 and logic 0 at pin 10. The frequency of the output depends on which of the resistors and capacitors R2 , C2 , R3 , C3 are connected but is preferably between 2 and 2.5 KHz. The integrated circuits IC1 and IC2 and parallel resistor and capacitor network R1 , C1 are present to act as switching means for the resistor and capacitor network R2, C2, R3, C3. IC1 is an integrated circuit of a type similar to IC3. The outputs on pins 10 and 11 of IC1 ' are 180° out of phase and are at a frequency fixed by the values of resistor R1 and capacitor C1 , but which is preferably 25Hz. IC2 is an integrated circuit of CMOS 4016 quad bilateral switch type. Pin 10 of IC1 is connected to pin 13 on IC2. Pin 11 on IC1 is connected to pin 5 on IC2. When a logic 1 is applied to pin 5 on IC2 this causes pins 3 and 4 of IC3 to be switched together, which connects capacitors C2 and C3 in parallel so that the output frequency of IC3 decreases by approximately 10%. When a logic 0 is applied to pin 5 of IC2 this disconnects capacitor C2, but simultaneously a logic 1 is applied to pin 13 which switches together pins 1 and 2 on IC3 thereby connecting resistor R2 in parallel with R3 so that the output frequency of IC3 increases by 10%. This process is repeated at the frequency of the output from IC1 , ie 25 times per second. Thus the output from IC3 is a frequency modulated square wave as shown schematically in Figure 4(m). The emitter collector path of transistor TR1 is in series with the positive supply as a switch for the integrated circuits IC1 , IC2, IC3. The base of transistor TR1 is connected via resistor R5 and diode D2 to control wire W which may be connected to a control line from a telephone fitted with a call alert facility, or it may be connected to further circuitry, to be described later. Resistors R5 and R6, capacitor C4 and diode D2 are present to prevent the transistor being falsely rendered conductive. An incoming call on a telephone in an alert mode will cause a negative signal or a train of, eg. 15 second negative pulses to be applied to wire W. This renders TR1 conductive and allows 12 volts to appear across A-B. An output signal as described before appears on pin 10 of IC3. This is amplified by transistors TR2 and TR3 and an audible tone resembling the ringing of a modern telephone is emitted by loudspeaker LS1 , at a level of approximately 104 dB acoustic. The output signal may be supplied to a second electo-optical transducer, e.g the vehicles headlamps or indicators to give a further indication of the receipt of the call. The arrangement described above is for use with a telephone including a call alert facility. If this facility is absent, then further circuitry may be connected in series to activate the apparatus, in the event of an incoming call. A telephone draws more current when it is transmitting than when it is in the standby mode. An incoming call will cause it to go into the transmit mode, thereby drawing more current from the electrical supply. The further circuitry is arranged to monitor the current and according to the level sensed provides a signal to switch on the apparatus. As shown in Figures 2 and 3, an integrated circuit IC4 monitors the current drawn by the telephone. A parallel combination of resistors R7, R8 is connected in the positive supply line between the positive battery terminal P1 and the positive terminal of the telephone P2 (Figure 3). IC4 is a dual comparator integrated circuit type LM393, and is a bistable device arranged to provide two outputs on pins 1 and 7. The output on pin 1 is normally logic 1 and the output on pin 7 is normally logic 0. When a current of greater than, eg. 1.5 amps flows through R7, R8, the logic states on pins 1, 7 invert. Resistors R9, R10, R11 , VR1 , R12 provide an input and output voltage reference for IC4. Integrated circuit IC5 is a multivibrator of CD-4047 type, arranged by resistor and capacitor network R17, C8 to output at pin 11 a train of pulses of logic 1 and logic 0 every 1.5 seconds. IC6 is a decade counter of CD4017 type and counts the pulses from IC5, which are applied to its input pin 14. The reset pin 15 is connected to pin 1 of IC1 , so that when the state on pin 1 inverts and the first clock pulse from IC5 arrives, the counter IC6 starts counting. The arrival of the first pulse from the clock IC5 causes the state on pin 3 of IC6 to go from logic 1 to 0, and causes a logic 1 to appear for 3 seconds on pin 2 of IC6. The second pulse causes a logic 1 on pin 4, and then similarly o pins 7, 10 and 1. Finally, arrival of the sixth pulse causes the output on pin 5 of ICβ to go to logic 1. Pin 5 is connected to pin 13, the inhibit pin, so that the logic 1 remains in that state until the reset pin 16 is activated, eg. by the caller ringing off. Integrated circuit IC7, of CD 4002 type, comprises a pair of quadruple input NOR gates, IC7A and IC7B. IC7A controls the sounder, via its pin 1. IC7B controls the muting of the sound system speakers HF, via its pin 13. Pins 9 and 10 are connected together, as are pins 11 and 12, to convert IC7B into a dual input NOR gate. When a logic 0 is applied to both of its inputs, a logic 1 state exists on the output pin 13, which is connected to the base of transistor TR6 via resistor R20. This causes the transistor TR6 to conduct, -so operating the relay RL1 , which then mutes the sound system speakers HF. IC7A gives a logic 1 output on pin 1 , only if all four inputs on pins 2, 3, 4, 5 are at logic 0. Pin 5 is connected to the ignition switch P3 so that when the ignition switch is off, pin 5 will be at logic 0. Pin 2 is connected to the output of the clock IC5. Pin 3 is connected to pins 13 and 5 on IC6. Pin 4 is connected to pin 3 of IC6. Pin 1 is connected to the base of transistor TR5 via resistor R13. Transistor TR5 is connected by its collector via resistor R21 to the positive supply terminal at P1. An output is taken from the collector of transistor TR6 and used as a signal to operate the call alert sounder apparatus of Figure 1 connected to P5. When logic 1 exists on pin 1 of IC7, TR5 conducts, causing its collector voltage to fall to zero. This will cause the call alert sounder to be activated for approximately 1.5 seconds, until the output of the clock IC5 until output on pin 11 goes to logic 1 , disabling pin 2 of IC7.. Figure 4 is a timing chart and shows the nature of the various logic states, at various stages of time. At time = 0 the call starts. The output states on pins 1 and 7 of IC4 invert, as shown in Figure 4 (a) and (b) . The clock IC5 starts producing 1.5 second pulses 4(c). The reset pin 15 is activated so that the counter IC6 can now function. The rising edge of the first clock pulse causes pin 3 of IC6 to go to logic 0 and remain in that state for the duration of the call 4(d). This means that IC7A is now enabled and will produce an output on pin 1 , on arrival of the first logic 0 from the clock IC5. IC7B is also enabled, so that the sound system speakers HF are muted 4(k). The rising edge also causes a three second logic 1 to appear on pin 2 (4(e)). The next rising edge of the clock pulse causes a similar state on pin 4 (4(f)). Thus the counter IC6 counts the first five clock pulses (4(e), (f), (g), (h), (i)). When the counter IC6 counts the sixth pulse a logic 1 appears on pin 5. This causes the counter IC6 to freeze and a logic 1 to remain on pin 5 until the call ends, and the reset pin 15 is activated. As pin 5 is also connected to one of the inputs of IC7A, this means that the call alert device can only ever produce 5 pulses, so that an incoming call will cause the sounder to ring 5 times (4(1)). However, the sound system speakers HF remain muted for the entire time of the call (4(k)). As shown in Figure 41 and in Figure 4m an enlarged time scale the call alert sounder at pin 10 of IC3 produces 5 pulses of a frequency modulated tone resembling a modern telephone. When telephone transmission is finished IC4 returns to its normal state. The normally logic 1 returns to pin 1 , thereby putting a logic 1 on the reset pin 15 of the counter IC6 and also on pins 9 and 10 of IC7B so causing the sound system mute function to cease. The normally logic 0 state returns to pin 7 of IC4 and disables the clock IC5. The circuit is now reset and back in the standby mode. The apparatus may be controlled by the 3-way rocker switch SW1 , whose position is indicated by the light emitting diodes yellow LΞD1 and red LΞD2. The switch SW1 and LED1 and LED2 are preferably mounted on the fascia panel of the vehicle. When the switch SW1 is set to its central position, this will allow the car telephone to operate normally and switch off automatically. When the switch SW1 is operated one way, so that the yellow LΞD1 is lit the telephone may be operated whilst the ignition switch of the vehicle is turned off. This will enable the user to operate the telephone, without causing the call alert sounder to operate. When the switch SW1 is operated the other way to light its red LED2, the device is now set so that an incoming call will cause the call alert sounder to sound five times. The muting of the sound system occurs irrespective of switch SW1 position. All known currently manufactured vehicle telephones are made to produce an approximately 0.5 second burst of transmission every 15 minutes. This is for the purpose of informing the telephone network of the location of the telephone. It is an advantage of the circuit that the call alert sounder and sound system mute function are not enabled for 1.5 seconds,, or until the first clock pulse arrives, and thus the circuit is able to ignore these bursts of transmission. We have determined that in the standby mode for a variety of different makes of telephone the current drawn from the battery ranges from about 175mmA to about 1A, whereas in the transmit mode the current ranges from about 1.5A to about 3A. Accordingly, the further circuitry is arranged to operated within the range of between a maximum standby current of 1A and a minimum transmit current of about 1.5A. It is a further advantage that the use of these accessories require no modification of the internal circuitry of the telephone. COMPONENTS LIST Diodes: Resistors: (ohms) D1 IN4148 D2 IN4148 R1 220K D2 BYX79C7V5 R2 470K D3 IN4001 R3 22K D4 IN4148 R4 4K7 D5 IN4148 R5 1 2 D6 IN4001 R6 2K7 DY IN4001 R7 0.22 L.E.D. 1 Yellow R8 0.22 L.E.D. 2 Red R9 10K R10 8K2 R11 10K R12 8K2 Transistors: R13 4K7 R14 10K TR1 BC557 R15 10K TR2 BC547 R16 150 TR3 BD131 R17 2M7 TR4 BC337 R 8 10K TR5 BC337 R19 4K7 TR6 BC337 R20 4K7 R21 10K R22 1K R23 1K Miscellaneous: Relay RL1 Matsushita RL1 Capacitors: 12 volt NC4D LS1 5", 8ohm 108 dB Horn Integrated Circuits IC1 CD4047 IC2 CD4016 IC3 CD4047 IC4 LM393 IC5 CD4047 IC6 CD4017 IC7 CD4002

Claims: CLAIMS 1. A telephone call indicator apparatus comprising switch means (TR1 , IC4, IC5, IC6) responsive to the receipt by a telephone of an incoming call; signal generating means (IC1 , IC2, IC3) controlled by the switch means (TR1 , IC4,5,6) and operative on receipt of the incoming call by the telephone to generate an output signal, and an electro-acoustic transducer (LS1 ) to which the output signal of the generator means (IC1 , IC2, IC3) is supplied and which in response thereto emits sounds simulating a ringing telephone. 2. Apparatus according to Claim 1 characterised in that the apparatus is mounted in a vehicle and is in circuit with a telephone also mounted in the vehicle. 3. Apparatus according to any preceding Claim characterised in that the switch means comprises a transistor (TR1 ) arranged to control the supply of power to the signal generating means (IC1, IC2, IC3) 4. Apparatus according to any preceding Claim characterised in that the signal generating means (IC1 , IC2 , IC3 ) is an oscillator which is controlled to provide a frequency modulated square wave output signal for supply to the transducer (LSD. 5. Apparatus according to any preceding Claim characte ised by a second electro-optical transducer to which the output signal of the generator means (IC1, IC2, IC3 ) is supplied, and which in response thereto gives a visual indication of receipt of an incoming call. 6. Apparatus according to Claim 5 characterised in that the switch means (TR1, IC4, IC5 , IC6 ) is arranged to sense the electrical power consumption of the telephone and to provide an indication signal indicative of the receipt of an incoming call in response to an increase in such consumption above a predetermined level. 7. Apparatus according to Claim 6 characterised in that the switch means (TR1 , IC4, IC5, IC6) provide the indication signal only when the increase in consumption has lasted for longer than a predetermined time interval. 8. Apparatus according to Claim 6 or 7 characterised in that the switch means (IC4, IC5 , IC6 ) comprises in combination a bi-stable device (IC4) switchable from a first state to a second state upon an increase of the power consumption above the predetermined level, a bi-stable multivibrator (IC5) arranged to emit a continuous square pulse output signal when the bi-stable device (IC4) is switched to its second state, and a counter (IC6) arranged to count the pulses emitted by the multivibrator ( C5 ) and to provide said indication signal only for a predetermined number of pulses from the multivibrator (IC5). 9. Apparatus according to any preceding Claim characterised by means (IC7B, RL1 ) arranged to mute any sound producing apparatus associated with the vehicle such as a radio or cassette player. 10. A vehicle incorporating apparatus according to any preceding Claim, the loudspeaker (LS1 ) being mounted so that it is audible from outside of the vehicle.

Inventors: BABER ALAN, GRIFFITH DAVID STUART, JONES KEVIN RHYS, BABER, ALAN, GRIFFITH, DAVID, STUART, JONES, KEVIN, RHYS
Applicants: BABER ALAN, GRIFFITH DAVID STUART, JONES KEVIN RHYS, BABER, ALAN, GRIFFITH, DAVID, STUART, JONES, KEVIN, RHYS
Application year: 1988
Main classification: H04M19
IPC codes: H04M19