GB2256772A

GB2256772A - Telephone with proximity switch

Info

Publication number: GB2256772A
Application number: GB9111444A
Authority: GB
Inventors: Hing-Chung So; Chi-Shun So
Original assignee: SO CHI SHUN; SO HING CHUNG
Current assignee: SO CHI SHUN; SO HING CHUNG
Priority date: 1991-05-28
Filing date: 1991-05-28
Publication date: 1992-12-16
Also published as: GB9111444D0; DE4217540A1; CN1069611A

Description

TELEPHONE The present invention relates to a telephone.

Conventional telephones require a user to place the telephone handset into an on-hook position on the base unit or remove the handset from that position or to press a button on the handset or cause the button to be pressed in order to switch the telephone between operation and standby modes.

The invention seeks to provide a telephone which is more convenient to use.

According to a. first aspect of the invention, there is provided a telephone which comprises a easing, a telephone circuitry within the easing for performing normal telephone operations such as sending out dialling signals or receiving a telephone call, and a sensor circuit provided within the casing and arranged to permit or enable the operation of the telephone circuitry in response to a user coming into close proximity to a part of the telephone casing.

there is provided a telephone which comprises a casing, a telephone circuitry within the casing for performing in an operation mode normal telephone operations such as sending out dialling signals or receiving a telephone call, and a sensor circuit provided within the casing and arranged to switch the telephone circuitry from a standby mode into the operation Accordiner to a second asDect of the invention mode in response to a user coming into close proximity to a part of the telephone casing, thereby permitting or enabling the operation of the telephone circuitry.

In a preferred embodiment, the sensor is arranged to permit 5 or enable the operation of the telephone circuitry in response to a user touching the said part of the telephone casing.

Preferably, the sensor circuit of either such telephone is arranged to detect whichever one or both of (a) electro-static charge and (b) frequency signal, from a user coming into close proximity to or touching the said part of the telephone casing.

In a preferred embodiment, the sensor circuit includes an oscillator having an inductor and a capacitor.

It is preferred that the oscillator is arranged to stop 15 oscillation in response to the sensor circuit detecting a user coming into close proximity to or touching the said part of the telephone casing.

Advantageously, the oscillator is tuned to oscillate at a f requency in the range of 1MHz to 3MHZ.

The sensor circuit is preferably arranged to permit or enable the operation of the telephone circuitry by completing an otherwise broken ground circuit or path of the telephone circuitry.

The sensor circuit may include a detector which is located on or adjacent the inner surface of the said part of the telephone casing.

It is preferred that the detector comprises a layer of electrically conducting material which is conveniently a carbon film deposited on the inner surface of the said part of the telephone casing.

In a preferred arrangement, the inductor and the capacitor are 10 connected to the detector.

The sensor circuit is preferably powered by a rechargeable battery which is arranged to be recharged during the operation of the telephone circuitry.

The telephone may be an one-piece telephone which provides in itself the telephone handset.

It is preferred that the sensor circuit is arranged also to prohibit or disable the operation of the telephone circuitry, whether immediately or with a predetermined time delay, in response to a user becoming no longer being in close proximity 20 to or touching the said part of the telephone casing.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a sectional f ront view of an embodiment of a telephone in accordance with the invention; Figure 2 is a sectional side view of the telephone of Figure 1; and Figure 3 is a circuit diagram of the internal components of the telephone of Figure 1.

Referring firstly to Figures 1 and 2 of the drawings, there is shown a telephone 10 embodying either aspect of the invention, which telephone 10 comprises a casing 11 formed by a f ront part 12 and a rear part 13. The circuitry of the telephone is provided on a printed circuit board 14 supporting twelve push-buttons 15 which are exposed through the front casing part 12 to form a key-pad 16.

The telephone 10 is an one-piece telephone, and therefore the -casing 11 provides in itself the handset which has a speaker 17 at the upper end and a microphone 18 at the lower end. Also at the lower end of the casing 11, there is provided a telephone line socket 19, by means of which the telephone (circuitry) 10 is connected to a commercial telephone line. A buzzer 19 is located on the inner side of the rear casing part 11, for generating a ringing signal in the presence of an incoming telephone call. Near each end of the rear casing part 13, there is deposited on the inner surface a layer of two carbon films 21 for, as will be described below, detecting a user touching the corresponding outer surface of the rear casing part 13.

Figure 3 shows the entire telephone circuitry which comprises the key-pad 16, an integrated circuit 22 and five other circuits, namely supply circuit 23, ringer circuit 24, flash circuit 25, voice circuit 26 and sensor circuit 27.

Terminals A-A represents the socket 19 at which an external telephone line and to which the supply circuit 23 and the ringer circuit 24 are connected. The ringer circuit 24 includes the buzzer 20 and is connected directly across the terminals A-A for receiving the ringing signal from a remote telephone exchange station. The supply circuit 23 includes a rectifier bridge 28 for rectifying the telephone line a.c.

supply voltage.

The rectifier bridge 28 has a positive output terminal 28a which provides the positive supply point for the entire circuitry and is connected to the VDD pin of the integrated circuit 22 and to the button "" of the key-pad 16. Negative output terminal 28b of the diode bridge 28 provides the supply (global) ground, and is connected to the VSS pin of the integrated circuit 22 and also to the local (as opposed to global) ground of the telephone circuitry but via a transistor Q, of the sensor circuit 27.It will be appreciated that whenever the transistor Q, is in an OFF state, the telephone circuitry will not be able to perf orm any normal telephone operations as will otherwise be in the operation mode, such as sending out dialling signals or receiving an incoming telephone call. This is the standby mode of the telephone circuitry, in which mode the ringer circuit 24 will nevertheless provide a ringing signal to alert the user in response to an incoming telephone call.

The voice circuit 26 includes the speaker 17 and the microphone 18. The microphone 18 is connected via a resistor R, across the positive supply point and the local ground. The speaker 17 is connected at one terminal to the local ground via a transistor Q4 and at the other terminal to the positive supply point via, apart from a current-limiting resistor, a transistor Q2. The transistor Q2 is controlled by another transistor Q3 which is in turn controlled by the microphone 18. In effect, the operation of the microphone 18 will override that of the speaker 17 by turning on the transistor Q3 in order to turn off the transistor Q2. The operation of the speaker 17 is also controlled by the "TONE" (output) pin of the integrated circuit 22 via a d.c. coupler 29 which controls the operation of the transistor Q4.

In the dialling mode, dialling signals from the "TONE" pin of the integrated circuit 22 is fed to appear cross the terminals A-A via a path including the transistor Q4, the speaker 17, the transistor Q2 and the rectifier bridge 28. Outgoing voice - 7 signals will be sent from the microphone 18 directly through the rectifier bridge 28 to the external telephone line, whereas incoming voice signals will be received by the speaker 17 through the rectifier bridge 28 and the transistor Q2 and 5 then fed to the local ground through the transistor Q4.

An independent power supply provided by a battery B is used in the sensor circuit 27. The positive terminal of the battery B is connected to the positive supply point, but its negative terminal is isolated from the supply ground by a capacitor C2.

The sensor circuit 27 incorporates a L-C harmonic oscillator 30. The oscillator 30 includes a transistor Q6, a feedback resistor Rz connected across the base and the collector (oscillator output) of the transistor Q6, a capacitor C, connected across the input of the oscillator 30 and the transistor base, a capacitor C5 connected across the transistor base and the negative terminal of the battery B, an inductor L, connected across the oscillator input and the negative battery terminal, and another inductor L2 connecting the transistor collector via a capacitor C5 to the negative battery terminal. The inductor L, is magnetically coupled to the inductor L 21 The oscillator input is connected to the carbon films 21 via a variable capacitor C7.

The oscillator 30 is designed to oscillate at a frequency in the order of IMH S to 3MH 9 in the standby mode of the telephone circuitry, and to have a relatively high tendency to instability when the oscillation frequency falls outside the normal range because of external disturbance. Oscillation of the oscillator 30 can no longer be maintained by reason of instability when the carbon films 21 and hence the oscillator input receive or collect the stray frequency signals and/or electro-static charge carried by the body of a user whenever the user touches the outer surface of the rear casing part 13.

At the output of the oscillator 30, there is a double stage switching /ampl if icat ion circuit formed principally by two transistors Q7 and Q8, the latter transistor Q8 controlling the ground switching transistor Q,. Between the oscillator 30 and the transistor Qp there are a series pair of diodes D, and D2, a resistor R3 and two capacitors CS and C4, being connected together as shown. The capacitor CS couples the oscillator output to circuit node X at between the diodes D, and D2. The oscillator output is connected to the positive supply point (the positive terminal of the battery B) by a resistor R4.

In the telephone standby mode, the oscillator 30 provides at the node X an oscillation potential which is sufficiently higher than the potential of the negative terminal of the battery B, thereby causing the diode D, and in turn the diode D 2 to conduct. The base potential of the transistor Q? is thus drawn down close to zero. Under this condition, both transistors Q, and Q8 and in turn the transistor Q, are all in the OFF state and thereby the local ground is separated from the supply ground.

In operation, a user is supposed to pick up the telephone 10, thereby touching the rear casing part 13, in order to make or answer a telephone call. When the user does this, the carbon films 21 will receive or collect the stray frequency signals and/or the electro-static charge from the user, whereby the oscillation of the oscillator 30 is interrupted. In the absence of the oscillation potential at the node X, the diode D, will cease conduction, thereby permitting the base terminal of transistors Q7 to rise. At this moment, the transistors Q?, Q8 and Q, are in turn switched on. The local ground is thus connected to the supply ground by the transistor Q,, thereby completing the ground circuit or path of the entire telephone circuitry. This enables the operation of the integrated circuit 22 and the voice circuit 26, etc. which are then properly connected to the external telephone line and ready to perform normal operations, such as permitting the user to dial out or answer an incoming telephone call.

The sensitivity of the oscillator 30 to detect the touching of the telephone casing 11 by a user or to respond to external disturbance caused by stray frequency signals and/or electro static charge from the user is adjustable by means of the capacitor C7. It is also understood that the wall thickness of the rear telephone casing part 13 plays a certain role in this regard.

The battery B is used to power the sensor circuit 27 for operation in the telephone standby mode, thereby avoiding drawing impermissibly excessive current from the external telephone line. A recharging circuit 31 including a resistor and a diode is provided f or the battery B, as shown, so that the battery B will be automatically recharged when the telephone is in the operation mode in which the negative terminal of the battery B is connected by the recharging circuit 31 to the supply ground.

After the user has finished using the telephone 10, the latter will normally be left aside. In the absence of touching of the rear casing part 13 by the user, the oscillator 30 will resume oscillation either immediately or with a predetermined time delay to prevent inadvertent disconnection of a call by brief or intermittent lack of touching by the user. Oscillation of the oscillator 30 results in turning off of the transistors Q?, Q8 and Q1. The local ground of the telephone circuitry is then again separated from the supply ground, and the telephone 10 resumes the standby mode.

It will be appreciated that the telephone 10 is convenient to use, without the necessity of an actual hooking on or off action which will otherwise have to be performed by a user. Also, the telephone 10 may be placed on, say, any uneven or a soft surface and in any position or orientation without affecting its operation.

Although the telephone 10 requires the user to touch its casing in order to start operation, it may be modified to respond to the user's hand coming into close proximity to or approaching close enough its casing, say within 1Omm to 20mm from the casing surface. The oscillator may be modified to have a higher sensitivity for the said or any other external disturbancet such as infra- red radiation emitted by the body of the user.

The invention has been described by way of example only, and various modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims

1. A telephone comprising a casing, a telephone circuitry within the casing for performing normal telephone operations such as sending out dialling signals or receiving a telephone call, and a sensor circuit provided within the casing and arranged to permit or enable the operation of the telephone circuitry in response to a user coming into close proximity to a part of the telephone casing.

2. A telephone comprising a casing, a telephone circuitry within the casing for performing in an operation mode normal telephone operations such as sending out dialling signals or receiving a telephone call, and a sensor circuit provided within the casing and arranged to switch the telephone circuitry from a standby mode into the operation mode in response to a user coming into close proximity to a part of the telephone casing, thereby permitting or enabling the operation of the telephone circuitry.

3. A telephone as claimed in claim 1 or claim 2, wherein the sensor is arranged to permit or enable the operation of the telephone circuitry in response to a user touching the said part of the telephone casing.

4. A telephone as claimed in any one of claim 1 to claim 3, wherein the sensor circuit is arranged to detect whichever one or both of (a) electrostatic charge and (b) frequency signal, I.

- 13 carried by a user coming into close proximity to or touching the said part of the telephone casing.

5. A telephone as claimed in any one of the preceding claims, wherein the sensor circuit includes an oscillator 5 having an inductor and a capacitor.

6. A telephone as claimed in claim 5, wherein the oscillator is arranged to stop oscillation in response to the sensor circuit detecting a user coming into close proximity to or touching the said part of the telephone casing.

7. A telephone as claimed in claim 5 or claim 6, wherein the oscillator is tuned to oscillate at a frequency in the range of 1MH z to 3MH 9.

8. A telephone as claimed in any one of the preceding claims, wherein the sensor circuit is arranged to permit or enable the operation of the telephone circuitry by completing an otherwise broken ground circuit or path of the telephone circuitry.

9. A telephone as claimed in any one of the preceding claims, wherein the sensor circuit includes a detector which is located on or adjacent the inner surface of the said part of the telephone easing.

10. A telephone as claimed in claim 9, wherein the detector comprises a layer of electrically conducting material.

11. A telephone as claimed in claim 10, wherein the layer of electrically conducting material is a carbon film deposited on the inner surface of the said part of the telephone casing.

12. A telephone as claimed in any one of claim 9 to claim 11 when dependent upon claim 5, wherein the inductor and the capacitor are connected to the detector.

13. A telephone as claimed in any one of the preceding claims, wherein the sensor circuit is powered by a rechargeable battery which is arranged to be recharged during the operation of the telephone circuitry.

14. A telephone as claimed in any one of the preceding claims, which telephone is an one-piece telephone, providing in itself the telephone handset.

15. A telephone as claimed in any one of the preceding claims, wherein the sensor circuit is arranged also to prohibit or disable the operation of the telephone circuitry, whether immediately or with a predetermined time delay, in response to a user becoming no longer being in close proximity to or touching the said part of the telephone casing.

16. A telephone substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

:z JD.