WO2004021384A2

WO2004021384A2 - Addressable relay assembly

Info

Publication number: WO2004021384A2
Application number: PCT/IB2003/003603
Authority: WO
Inventors: Tom Horan
Original assignee: Xpeqt Ag
Priority date: 2002-08-29
Filing date: 2003-08-29
Publication date: 2004-03-11
Also published as: AU2003259395A1; WO2004021384A3; GB0220050D0

Abstract

An addressable relay assembly comprises an electrically conducting coil 908, a magnetic switch 909 and a control means 907. The electrically conducting coil 908 generates a magnetic field when an electric current flöws therethrough to operate the magnetic switch 909 which is located within the coil 908. The magnetic switch 909 is closed when a magnetic field of greater than a particular threshold value is generated by the coil 908 and open otherwise. The control means has one or more input pins 902-906 for receiving signals from an external source, processing said received signals and identifying whether said signals are addressed to the relay and thereby controlling the current flow in the coil 908 in response to said signals.

Description

ADDRESSABLE RELAY ASSEMBLY

The present invention relates mainly to an addressable relay and to an electronic testing interface comprising a number of addressable relays.

Conventional electronic relays comprise a magnetically actuated switch disposed within a conducting coil. When a current is passed through the coil it generates a magnetic field which closes the magnetic switch, the switch reverting to the open position when the field is removed by cutting the current flow in the coil.

A use of relays is in electronic testing equipment such as electronic testing interfaces. A relay can be used to make a low impedance contact between a signal generator or a measuring device and an input/output pin on an electric circuit and in particular on an integrated circuit. The relay when turned off also offers a high isolation between the generator/measuring device and the circuitry to be tested.

In a typical electronic testing interface a number of relays are provided, arranged in such a manner that any particular signal generator or detector connected to the interface may be connected to any desired input/output pin of the circuit to be tested by closing appropriate relay switches in order to form an electrical path through the interface. This allows the testing device to be adapted simply and easily to test a wide variety of different circuits. To achieve this flexibility these interfaces typically contain an array of relays (normally a square/rectangular array) mounted on a printed wiring board and a number of contacts along one side of the array for signal generators and detectors and a number of contacts along a second orthogonal side of the array for connection to input/output pins from the circuit to be tested. The conductors on the printed wiring board can then be arranged so that any contact on the first side of the array can be joined to any contact on the second side of the array by closing a relay at the intersection point. With a large number of relays the connections typically become very complicated and take up a large amount of physical space. It would be desirable to be able to provide a test unit with the same amount of flexibility but with a less complicated and less space consuming design.

It is therefore an object of the present invention to provide an addressable relay assembly. It is also an object of the invention to provide an improved relay electronic testing interface incorporating a number of addressable relay assemblies.

According to a first aspect of the present invention there is provided an addressable relay assembly comprising:

An electrically conducting coil, for generating a magnetic field when an electric current flows therethrough;

A magnetic switch located within the coil, said switch being closed when a magnetic field of greater than a particular threshold value is generated by the coil and open otherwise; and

Control means, having one or more input pins for receiving signals from an external source, said control means processing said received signals and identifying whether said signals are addressed to said relay and controlling current flow in the coil in response to said signals.

Preferably the magnetic switch is a reed switch. Preferably the control means is an integrated circuit. Most preferably the control means, the coil and the magnetic switch are provided in a single housing.

Preferably said control means incorporates a non-volatile memory containing an identification code. Alternatively, said control means may have a volatile memory wherein an identification mode can be stored upon powering up.

Preferably, a sensor is provided to confirm operation of the coil. Most preferably said sensor is a Hall effect sensor. Preferably said housing is a square or rectangular housing and said coil is mounted at substantially 45° to either the base or to other edges of said housing.

Preferably said control means in addition to receiving signals can, if required, transmit or retransmit said signals or similar signals. Most preferably said control means can carry out a diagnostic test on said coil in response to input signals and can output signals relating to the operation thereof.

Preferably said input pins extend through said housing and preferably said input pins are all provided on a single face of said housing.

Preferably said input pins are symmetrically positioned about the centre line of the housing. Most preferably the input pin for receiving input power and the input pin for receiving communication signals from an external source are interchangeable. This enables the relay to operate when mounted in either of two orientations.

According to a second aspect of the present invention there is provided a testing interface for electronic circuitry comprising:-

a first set of contacts on a first side of said interface for connection to electronic testing equipment;

a second set of contacts on a second side of the interface for connection to the inputs/outputs of the circuit to be tested;

an array of relays connected to said first and second sets of contacts, wherein any contact from said first set and any contact from said second set may be electrically connected by closing one or more relays within the array; and

a communication controller for outputting signals to said addressable relays via suitable communication means;

wherein each relay is an addressable relay and said signals include an address or identification code in order that only the particular relay with an identical address or identification code responds to any particular signal.

Preferably said addressable relays are addressable relay assemblies of the type described in relation to the first aspect of the present invention.

Said electronic testing equipment may include signal generating devices and signal detecting devices.

Said communication means may connect said addressable relays in parallel or in series. If said relays are connected in parallel preferably each addressable relay incorporates a non-volatile memory storing an identification or address code. If said relays are connected in series, preferably each said relay incorporates a volatile memory wherein an identification code can be stored when the interface is powered up.

Preferably said communication means allows two-way communication with said communications controller. Most preferably said communications controller can instruct said relays to perform a self-test and transmit the results to said communications controller.

Said communication means may be provided by electrical connection, infrared, optical or radio frequency link as is desired. Preferably means are provided to allow synchronous or time interval switching of a number of relays.

Preferably said addressable relays are mounted on a printed circuit board in a square or rectangular array. Most preferably, said first and second sets of contacts are provided on adjacent perpendicular sides of the array.

Preferably neighbouring relays in the array are mounted so that their respective coil axes are substantially perpendicular.

In order that the invention is more clearly understood, one embodiment of the invention will now be described further below with reference to the accompanying drawings in which:

Figure 1 shows a known arrangement for mounting relays in an array to form a testing interface;

Figure 2 shows an alternative known arrangement for mounting relays in an array to form a testing interface;

Figure 3 shows an arrangement for mounting relays in an array to form a testing interface in accordance with one embodiment of the present invention;

Figjure 4 shows an alternative arrangement for mounting relays in an array to form a testing interface in accordance with a second embodiment of the present invention;

Figure 5 shows an addressable relay assembly in accordance with one embodiment of the present invention; and

Figure 6 shows how the input pins of an addressable relay in accordance with the present invention may be connected such that the addressable relay can be mounted on a printed circuit board in one of two different orientations.

Referring to figure 1 a test interface arrangement representative of the current art is shown. A plurality of relays, 411-433, are arranged in a regular array upon a printed circuit board. Each relay comprises a coil 211- 233, a pair of electrical contacts to said coil and a pair of switched contacts wherein the switched contacts are joined by a magnetic switch 111-133 located within or otherwise adjacent to the coil. The state of the switch 111-133 is governed by whether or not a threshold magnetic field is generated by the coil 211-233 when a current flows therethrough. Typically said switch 111-133 is a reed switch but other magnetically operated switches may be used instead if desired. An array of three rows and three columns is shown in the present illustration but arrays of other sizes and arrays with differing numbers of rows and columns are also possible. Electrical connections are provided on the PCB such that there are provided two connections to the coil 211-233 and two connections to the switched contacts of each relay 411-433.

A plurality of electrical conductors, 102,103,104, pass through the array in a first direction and a further plurality of electrical conductors, 105, 106, 107, pass through the array in a second direction orthogonal to the first direction. Conductor 102 passing through the array in the first direction connects to a first switched contact connection on each relay, 411 , 412, 413, in the first column. In a similar manner, conductor 103 passing through the array in the first direction connects to a first switched contact connection on each relay, 421 , 422, 423, in the second column and conductor 104 passing through the array in the first direction connects to a first switched contact connection on each relay, 431 , 432, 433, in the third column. In similar manner conductors 105, 106 and 107 pass through the array in the second direction and connect to a second switched contact connection of each relay in a row.

Common connection 101 passes through the entire array and is connected to the first coil connection of each relay 411-433 in the array. The second coil connection of each relay is connected to an individual electrical conductor 511-533 for each relay. Said individual conductors 511-533 are brought out from the array to be connected to a driver means external to the array. The external driving means is used to pass current through the relay coils and thereby activate the magnetic switches in each relay. Providing each relay with an individual connection to the driving means allows each relay to be separately activated and deactivated.

In use as a test interface one or more of electrical conductors 102, 103, 104 may be individually connected to either a signal source or a measuring device. Electπcal conductors 105, 106, 107 may be individually connected to one or more contacts of the electrical circuit under test. Connecting a suitable driving current to one or more of the separate electrical conductors 511-533, will energise the driving coil 211-233 of one or more of the relays 411-433 and thereby connect the signal sources or measuring devices to one or more of the contacts of the electrical circuit under test.

Whilst this arrangement provides the necessary flexibility to connect any signal source or measuring device available to a desired circuit input/output contact it requires very many individual electrical connections.

Due to the number of connections required and their complex nature a relay array such as this is bulky and expensive.

An alternative array with a less complex web of electrical connections is shown in figure 2. Conductor 101 from the first embodiment has been replaced by three conductors 601 , 602 and 603, which each connect to the first coil connection of each relay in a column. Similarly, individual electrical conductors 511-533, have been replaced by electrical conductors 501 , 502 and 503, which each connect to the second coil connection of each relay in a row.

Connecting a suitable voltage across one of the column electrical conductors 601 , 602, 603 and one of the row conductors 501 , 502, 503 will cause the relay that is common to the row and the column thus selected to be operated. Since the coils of the relays are resistive, diodes 311-333 are needed to block reverse conduction of the coils and avoid operation of unwanted relays due to sneak paths. The total number of connections for driving the coils 211-233 is the sum of the number of rows and the number of columns as opposed to the embodiment previously described wherein the number of driving connections is equal to the product of the number of rows and the number of columns (i.e. the total number of relays) plus one. The disadvantage of such an arrangement is that within the array only a limited number of combinations of relays 411-433 can be independently operated at one time.

Figure 3 shows a first embodiment of a relay array according to the present invention. The conventional relays 411-433 of the first two embodiments are replaced by addressable relays 711-733 each incorporating a control means 811-833 in addition to a coil 211-233 and a pair of magnetically switched contacts 111-133. The control means governs the flow of current through the coil in response to signals received from an external communication controller (not shown).

Each control means is connected to a power supply via common electrical connections 101 and 108 and is additionally connected to said external communication controller via communications conductors 710, 720 & 730. Said communications conductors 710-730 may be combined externally to the array. Each control means additionally contains non- volatile storage means holding an address or identification code. The identification code is used by the control means to determine those communication signals that are to be responded to. Thus each relay may be connected to common power lines and a common communication line but can still be individually activated and/or deactivated. This allows the amount and complexity of wiring for an array to be reduced thereby reducing its size without compromising its functionality.

The communications conductors 710, 720 & 730 can be replaced with optical or infrared communication links if screening is a concern. If screening is not a concern radio frequency communications links can be used.

The identification code should be at least locally unique. The code can be pre-programmed into non-volatile memory to identify a specific relay at a specific location, said relay being inserted in the specific location during manufacture of the interface. More conveniently, however, a batch of relays with different identification codes is used to manufacture the interface, the relays being placed in non-specific positions and the communications controller interrogates the relays and leans which relay is placed in which location in the array.

A variant of this embodiment is shown in figure 4 the control means

811-833 ύf the relays 711-733 in this embodiment do not have non-volatile storage means and are connected in a "daisy chain" manner i.e. in series rather than parallel. Additionally the communication conductors 810, 820 & 830 connect the first relays in each row to the established communications controller, the second relay in each row being connected to the first relay by communications conductor 810', 820', 830' etc. In this arrangement when the interface is initially powered up the communications controller interrogates each relay in turn allocating each relay an identifying code. In subsequent operation signals which arrive at the first relay and carry an identifying code relating to a later relay are passed along the line to the next relay and so on until the desired relay is reached. This technique overcomes the limitation of each control means needing non-volatile storage means, which must be programmed to contain an at least locally unique identification code. Thus the control means used may be less complex and therefore cheaper while achieving the same results as in the previously described embodiment.

A block diagram of an addressable relay assembly suitable for mounting on a PCB for use in these test interfaces is shown in figure 5, a coil 908, a magnetic switch, in this case a reed switch 909 located within the coil 908 and a control means 907, which may be a microprocessor are all mounted within a rectangular housing 901. Other shapes for the housing can be considered but a square or rectangular housing is best adapted to close tessellation in an array. The axis of coil 908 is at angle to the base of the housing 901 and this angle is preferably 45 degrees. Adjacent relays in an array can thereby be mounted with their respective coil axes perpendicular, an arrangement that substantially reduces the effects of magnetic cross talk

In the base of the housing 901 are a plurality of input/output pins, 902, 903, 904, 905, 906. The pins 902-906 are shown arranged in a symmetrical pattern about the centre line although other pin spacings may be used if desired. With a symmetrical pin arrangement it is possible to design a relay which will operate successfully when it is mounted with its coil axis in either direction.

The reed switch 909 is connected to the outer two pins 902 and

906 via connections 912 and 913. The pins 902 and 906 are isolated from pins 903-905 to avoid communications signals interfering with signal generators or measuring equipment used in the testing process. The control means 907, receives power and communications signals from the pins 903-905 on the base of the housing 901. The control means 907 operates in response to signals received by the pin 903-905 to either allow or prevent current from flowing through the coil 908. Typically pin 904 is connected to earth, the input power line being connect to either 903 or 905, the other of these pins 903, 905 being used to connect to the communication signals. In a preferred method of communication, communication signals are affected by pulsing the voltage on one of pins 903,905. Which pin acts as the input power pin and which pin is the communications connection is determined by in which direction the relay is mounted.

An arrangement is shown in figure 6 for providing a reversibly mountable relay 900 wherein the input power can be separated from communications signals. Input pins 903 and 905 are connected to both on gate 920 and a pair of diodes 919. The output of diodes 919 is the power supply 921 to the relay 900. Provided at least one of pins 903 and 905 is at a positive voltage relative to pin 904 then the power supply 921 to the control means is maintained. A voltage pulse dropping below the threshold of AND gate 920 on either pin 903 or pin 905 will vary the output of AND gate 920. This variation of the output 922 of gate 920 corresponds to the variation of the input communications signals.

Advantageously, in such a communication method, pins 903 and

905 can be connected to an arrangement of diodes so that they are effectively interchangeable. This allows neighbouring relays to be mounted with oppositely oriented coil axes without complex printed wiring arrangements.

The control means may also include provision for monitoring the performance of the coil 908 by means of a Hall effect device, a reed switch or other magnetic detector (not shown). The magnetic detector is used to detect the stray field from the coil 908 and may be used to confirm or to adjust the current in the coil 908 from an initial high level required to operate the relay 909 to a second lower level required to maintain the relay in the operated condition.

Of course, it is to be understood that the invention is not to be restricted to the details of the above described embodiment which is described by way of example only. For instance there are other aspects of design well known to those skilled in the art of the design of electronic and electro mechanical modules intended for mounting on a printed wiring board that do not form part of the invention and have been omitted from the description herein for the sake of clarity. Such aspects may include mounting means, spacers, thermal management means, insulation and vibration suppression means.

Claims

1. An addressable relay assembly comprising:

2. A relay as claimed in claim 1 wherein the magnetic switch is a reed switch.

3. A relay as claimed in claim 1 or claim 2 wherein the control means is an integrated circuit.

4. A relay as claimed in any preceding claim wherein the control means the coil and the magnetic switch are provided in a single housing.

5. A relay as claimed in any preceding claim wherein control means incorporates a non-volatile memory containing an identification code.

6. A relay as claimed in any preceding claim wherein said control means incorporates a volatile memory wherein an identification mode can be stored upon powering up.

7. A retay. as claimed in any preceding claim wherein a sensor is provided to confirm operation of the coil.

8. A relay as claimed in any preceding claim wherein said sensor is a Hall effect sensor.

9. A relay as claimed in any preceding claim wherein said housing is a square or rectangular housing.

10. A relay as claimed in any preceding claim wherein said coil is mounted at substantially 45° to edges of said housing.

11. A relay as claimed in any preceding claim wherein said control means in addition to receiving signals can transmit or retransmit said signals or similar signals.

12. A relay as claimed in any preceding claim wherein said control means can carry out a diagnostic test on said coil in response to input signals and can output signals relating to the operation thereof.

13. A relay as claimed in any preceding claim wherein said input pins extend through said housing.

14. A relay as claimed in claim 14 wherein said input pins are all provided on a single face of said housing.

15. A relay as claimed in claim 15 wherein said input pins are symmetrically positioned about the centre line of the housing.

16. A relay as claimed in any preceding claim wherein the input pin for receiving input power and the input pin for receiving communication signals from an external source are interchangeable.

17. A testing interface for electronic circuitry comprising:- a first set of contacts on a first side of said interface for connection to electronic testing equipment;

18. A testing interface as claimed in claim 17 wherein said addressable relays are addressable relay assemblies as claimed in any one of claims 1 to 16.

19. A testing interface as claimed in claim 17 or claim 18 wherein said electronic testing equipment includes signal generating devices.

20. A testing interface as claimed in any one of claims 17 to 19 wherein said electronic testing equipment includes signal detecting devices.

21. A testing interface as claimed in any one of claims 17 to 20 wherein said communication means connects said addressable relays in parallel.

22. A testing interface as claimed in any one of claims 17 to 21 wherein said communication means connects said addressable relays in series.

23. A testing interface as claimed in any one of claims 17 to 22 wherein each addressable relay incorporates a non-volatile memory storing an identification or address code.

24. A testing interface as claimed in any one of claims 17 to 23 wherein each said relay incorporates a volatile memory wherein an identification code can be stored when the interface is powered up.

25. A testing interface as claimed in any one of claims 17 to 24 wherein said communication means allows two-way communication with said communications controller.

26. A testing interface as claimed in any one of claims 17 to 25 wherein said communications controller can instruct said relays to perform a self-test and transmit the results to said communications controller.

27. A testing interface as claimed in any one of claims 17 to 26 wherein said communication means are provided by electrical connection.

28. A testing interface as claimed in any one of claims 17 to 27 wherein said communication means are provided by an infrared link.

29. A testing interface as claimed in any one of claims 17 to 28 wherein said communication means are provided by an optical link.

30. A testing interface as claimed in any one of claims 17 to 29 wherein said communication means are provided by a radio frequency link.

31. A testing interface as claimed in any one of claims 17 to 30 wherein means are provided to allow synchronous or time interval switching of a number of relays.

32. A testing interface as claimed in any one of claims 17 to 31 wherein said addressable relays are mounted on a printed circuit board in a square or rectangular array.

33. A testing interface as claimed in claim 32 wherein said first and second sets of contacts are provided on adjacent perpendicular sides of the array.

34. A testing interface as claimed in claim 33 wherein neighbouring relays in the array are mounted so that their respective coil axes are substantially perpendicular.