GB1563387A

GB1563387A - Wrist transmitter

Info

Publication number: GB1563387A
Application number: GB2172378A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-24
Filing date: 1978-05-24
Publication date: 1980-03-26

Description

(54) WRIST TRANSMITTER (71) I, STAVELEY GRAHAM ANDERSON SWALES, a British subject of Clifton Garage, Clifton, Morpeth, Northumberland, NE61 6DG, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a wrist transmitter.

The wrist transmitter in accordance with the invention is designed for use in an emergency to emit a distress or alarm signal which will be picked up at a receiver station. It may be used by the elderly or incapacitated for example in hospital or may be used by security staff or as an anti-kidnap alarm.

In my prior British Patent No. 1,469,509 I described and claimed a wristlet comprising a casing having a strap by which it is adapted to be mounted on the wrist of a user, the casing housing a radio transmitter which has an actuator by which it may be operated, the casing including a recess in which a removable timepiece may be mounted to be in combination with the transmitter.

Whilst the arrangement disclosed in my prior patent worked satisfactorily its construction did not enhance its appearance and compactness. An object of the present invention is to provide an improved wrist transmitter.

According to the present invention a radio transmiter unit comprises a casing adapted to receive a strap by means of which it may be secured about the wrist of the user, and a radio transmitter and a time-piece disposed within the casing, the radio transmitter being disposed within a recess in the casing and the time-piece being situated in said recess over the transmitter.

The time-piece is preferably a generally planar digital quartz movement time-piece.

The radio transmitter preferably comprises a tone generator, a radio frequency oscillator and an aerial the output of the transmitter being matched to the impedence of the aerial by means of a step-up transformer.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 illustrates an exploded view of a first embodiment of the invention; Figure 2 illustrates a second embodiment of the invention in plan view assembled; and Figure 3 is a circuit diagram of the preferred circuitry.

In Figure 1 of the drawings a wrist transmitter comprises a casing 1 having a central, generally circular cavity 2 with a rectangular recess extension 3 at one end. About the mouth of the cavity 2 is a rebate 4 and extending through the wall of the casing 1 into the cavity 2 are two apertures 5.

The cavity 2 as shown receives a transmitter 6 which is powered by an electric cell 7 which fits into the rectangular recess extension 2.

The transmitter 6 is arranged to be in communication with a telescopic aerial 8 affixed to the outside of the casing 1 and is actuated by an actuating button 9 which passes through one of the apertures 5. The other aperture 5 receives a small light emitting diode 10 which is illuminated during transmission to give the user a visual indication of operation.

Suspended over the transmitter 6 is a thin, substantially planar watch movement 11 which is protected by a watch case and lens 12 The watch case and lens 12 has an aperture for receiving a watch winder 13 and is seated on the rebate 4. The complete unit is held together by a bezel 14 secured to the casing 1 by securing screws 15.

In Figure 2 which shows an alternative arrangement the assembly is very similar except that the watch movement and lens are one combined digital unit 16 such as a quartz watch movement. For this embodiment a suitable operating button 17 for effecting the digital display is provided as shown. The embodiments disclosed are a great improvement over my previous proposal since the watch movement is situated over the transmitter providing a more compact and desirable unit. As shown in Figure 2 the wrist transmitter is secured to a user's wrist by means of a suitable strap 18, a strap is also provided with the embodiment of Figure 1 but it has been omitted for clarity.

In Figure 3 the preferred circuitry of the transmitter is diagrammatically illustrated.

The transmitter is an amplitude modulated micro-miniature transmitter arranged to radiate a nominal tone of 750 cycles per second on a frequency of 27-45 Megahertz. The circuit includes, to left in Figure 3, an integ- rated circuit tone generator FX205, the frequency of which is determined by R1, Cl and the period of transmission is determined by R2, C2; for example the period of transmission may be five seconds. The tone generator is connected to a radio frequency oscillator, shown to the right in Figure 3, by means of a low pass filter which comprises two RC networks and which is connected between the pin 3 of FX205 and the transistor T1. The low pass filter filters out unwanted harmonics generated by the tone generator.

The transistor T1 acts as an amplitude modulated current source which in turn supplies AF modulation to the crystal controlled radio frequency oscillator T. The oscillator T2 uses a 3rd overtone parallel resonant crystal and the radio frequency power is developed in the circuit L,C3. L, consists of a step up transformer which effectively matches the comparatively low output impedence of T2 to the high impedence presented by the short aerial Ae which is principally capacitively reactive at 27-45 Megahertz.

A step-up transformer is used to obtain correct electrical matching since in a conventional transmitter the output has a higher impedence than the aerial whereas the reverse is the case in the present invention. In order to keep the dimensions of the transformer to a minimum one winding is made concentric to the other on a common former and by using thinner wire for the secondary winding the required step-up ratio can be obtained without increasing the former length beyond that required by the primary winding. In order to facilitate winding the secondary thin wire is wound on the former first and the primary thicker wire is wound on top.

Although the operation of the transmitter is indicated by a light emitting diode this could be replaced by a buzzer or other audible transducer to help locate the person seeking assistance. The watch movement is readily removed for maintenance or replacement by releasing the securing screws. The casing may be metal, plastics or any other suitable material.

WHAT I CLAIM IS: 1. A radio transmitter unit comprising a casing adapted to receive a strap by means of which it may be secured about the wrist of a user, and a radio transmitter and a timepiece disposed within the casing, the radio transmitter being disposed within a recess in the casing and the time-piece being situated in the said recess over the transmitter.

2. A radio transmitter unit according to Claim 1 wherein the time-piece is a generally planar digital quartz movement.

3. A radio transmitter unit according to Claim 1 wherein the time-piece includes a generally planar movement and a separate lens.

4. A radio transmitter unit according to Claim 1, 2 or 3 wherein the radio transmitter and time-piece are retained within the casing by means of a bezel releasably secured to the casing.

5. A radio transmitter unit according to any one of the preceding claims wherein the radio transmitter comprises a tone generator, a radio frequency oscillator and an aerial the output of the transmitter being matched to the impedence of the aerial by means of a step-up transformer.

6. A radio transmitter unit according to Claim 5 wherein the aerial is a telescopic aerial.

7. A radio transmitter unit according to Claim 5 or 6 wherein the step-up transformer includes a secondary winding of thinner wire than the primary winding, the primary winding being wound on top of the secondary winding.

8. A radio transmitter unit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The transmitter is an amplitude modulated micro-miniature transmitter arranged to radiate a nominal tone of 750 cycles per second on a frequency of 27-45 Megahertz. The circuit includes, to left in Figure 3, an integ- rated circuit tone generator FX205, the frequency of which is determined by R1, Cl and the period of transmission is determined by R2, C2; for example the period of transmission may be five seconds. The tone generator is connected to a radio frequency oscillator, shown to the right in Figure 3, by means of a low pass filter which comprises two RC networks and which is connected between the pin 3 of FX205 and the transistor T1. The low pass filter filters out unwanted harmonics generated by the tone generator. The transistor T1 acts as an amplitude modulated current source which in turn supplies AF modulation to the crystal controlled radio frequency oscillator T. The oscillator T2 uses a 3rd overtone parallel resonant crystal and the radio frequency power is developed in the circuit L,C3. L, consists of a step up transformer which effectively matches the comparatively low output impedence of T2 to the high impedence presented by the short aerial Ae which is principally capacitively reactive at 27-45 Megahertz. A step-up transformer is used to obtain correct electrical matching since in a conventional transmitter the output has a higher impedence than the aerial whereas the reverse is the case in the present invention. In order to keep the dimensions of the transformer to a minimum one winding is made concentric to the other on a common former and by using thinner wire for the secondary winding the required step-up ratio can be obtained without increasing the former length beyond that required by the primary winding. In order to facilitate winding the secondary thin wire is wound on the former first and the primary thicker wire is wound on top. Although the operation of the transmitter is indicated by a light emitting diode this could be replaced by a buzzer or other audible transducer to help locate the person seeking assistance. The watch movement is readily removed for maintenance or replacement by releasing the securing screws. The casing may be metal, plastics or any other suitable material. WHAT I CLAIM IS:

1. A radio transmitter unit comprising a casing adapted to receive a strap by means of which it may be secured about the wrist of a user, and a radio transmitter and a timepiece disposed within the casing, the radio transmitter being disposed within a recess in the casing and the time-piece being situated in the said recess over the transmitter.