WO1994022238A1

WO1994022238A1 - Data transmission

Info

Publication number: WO1994022238A1
Application number: PCT/GB1994/000551
Authority: WO
Inventors: Peter Byford
Original assignee: Thames Water Utilities Limited
Priority date: 1993-03-18
Filing date: 1994-03-18
Publication date: 1994-09-29
Also published as: GB2291566B; GB2291566A; GB9305603D0; AU6217094A; GB9519051D0

Abstract

A probe (10) has a coil (23) for inductive transmission of signals from a source when the probe is in proximity to a receiver. A switch (41) connects the coil (23) to the source in response to a position sensor (21, 22) of the position of a plunger (16) relative to the body of the probe, the position being changed by relative approach to the receiver. The sensor may be magnetic and the sensor and switch may be combined in a Hall Effect device.

Description

DATA TRANSMISSION

When information in the form of electrical signals is transferred by an inductive probe, it has in the past been necessary to initiate the passage of the information signals through the inductive element by hand once the inductive probe has been placed in the correct position. The present invention enables the initiation to be effected automatically.

According to the invention there is provided an inductive probe comprising an electrical coil for carrying electrical signals representing information to be transmitted, means including a switch for causing passage of said signals through said coil, and a resiliently mounted plunger adapted to be moved when the probe is brought into engagement with another object, movement of the plunger activating said switch.

An example of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section through an inductive probe.

Figure 2 is a longitudinal section through a station with which the probe of Figure 1 is used, and

Figure 3 is a detail of Figure 1, in a modified arrangement.

An inductive probe 10 comprises a pistol-shaped grip 11 which is formed with an entry 12 for cables 13 leading to electrical components within the probe. At the operative end of the casing, a cavity 14 is formed within the walls of the probe which have an inturned lip 15, within which cavity a spring loaded plunger 16 with a rear shoulder 17 is contained, the plunger being biased outwards of the cavity 14 by a spring 18 until the shoulder 17 engages the lip 15. The end 19 of the plunger facing the inner end of the cavity is provided with a permanent magnet 21 and the inner end of the cavity is provided with a Hall Effect switch 22 connected to cables 13 from the cable entry 12. At the end of the plunger facing the exterior of the probe, an inductive coil 23 is mounted, connected to cables 13 from the cable entry 12.

The normal position of the probe is as illustrated in Figure 1. When the casing approaches the station 30 of Figure 2 located to the right-hand side of Figure 1, the protruding end 19 of the plunger engages the face 31 of the station 30 and the plunger 16 is pressed towards the left of Figure 1, compressing the spring 18 and bringing the magnet 21 into close proximity to the Hall Effect switch 22. The Hall Effect switch 22 is activated by the change of magnetic field caused by the movement of the magnet and sends a control signal through the cables 13 to an initiating circuit 41 beyond the cable entry 12, which circuit causes a signal to be generated in the coil 23, the signal being inductively transferred to the coil 32 in the station 30 into engagement with which the plunger 16 has been brought. The desired data communication can then take place as a result of the inductive connection between the coils 23 and 32.

The circuit 41 is connected to the Hall Effect switch 22 and activates a switch 42. The switch 42 connected

(Fig. 1) in the connection from the coil 23, connecting it to an interrogating signal generator 43 and to a meter reading recorder 44. When the switch 42 closes, interrogating signals are transmitted to the station 30 by means of the coil 23 and meter readings from the station 30 are recorded by the recorder 44.

In an alternative arrangement shown in Figure 3 the circuit 41 is connected directly to the generator 42. Activation of the switch 22 causes the circuit 41 to energise the generator so that a burst of interrogating signals is generated and transmitted to the station through the coil 23. The station 30 responds to the signal burst and transmits meter reading signals back through the coil 23 which reading signals are recorded in the recorder 44.

These arrangements have an advantage over a manual operation of an initiating switch to cause the generation of the signal within the coil 23 because in this arrangement the signal will only be transmitted when the plunger 16 has been pressed home by engagement with an object but will be transmitted immediately this event has happened, so there will be no precocious transmission of the signal and yet it will be transmitted with the minimum of delay once the right conditions have been established.

It will be noted that the pistol grip 11 has no trigger, since no manual activation of a button to cause transmission of the signal to the coil 23 is required.

Claims

1. An inductive probe comprising an electrical coil (23) for carrying electrical signals representing information to be transmitted, means including a switch (22, 41, 42) for causing passage of said signals through said coil, and a resiliently mounted plunger (16) adapted to be moved when the probe is brought into engagement with another object, movement of the plunger activating said switch.

2. A probe as claimed in claim 1 comprising a magnet (21) carried by said plunger and a magnetic sensor (22) adapted to activate said switch (41), said sensor responding to the movement of the magnet on the plunger.

3. A probe as claimed in claim 2 wherein said sensor and said switch are parts of a Hall Effect switch.

4. A probe as claimed in any one of claims 1 to 3 wherein said coil is mounted on said plunger.

5. A meter reading device comprising an interrogating signal generator (43), a meter reading signal recorder (44) and an inductive probe as claimed in any preceding claim, said switch (41) being arranged to cause passage of signals from the generator (43) to the coil (23) and from the coil (23) to the recorder (44).

6. A device as claimed in claim 5 wherein the generator (43) is responsive to activation of said switch (41) to generate interrogating signals and to pass them to the coil (23).

7. A device as claimed in claim 5 wherein the switch (41, 42) is connected between the generator (43) and the coil (23) to pass interrogating signals from the generator (43) to the coil (23) when activated by said plunger (16).

8. A device as claimed in any one of claims 5 to 7 in combination with a meter interface (30), the interface comprising a pressure pad (31) for engagement with said plunger, the interface further comprising a coil (32) for inductive coupling with the coil (23) of the device.