WO2000059079A1

WO2000059079A1 - Intelligent power board

Info

Publication number: WO2000059079A1
Application number: PCT/AU2000/000246
Authority: WO
Inventors: Roger Hamline Stafford Riordan
Original assignee: Cybec Pty. Ltd.
Priority date: 1999-03-25
Filing date: 2000-03-24
Publication date: 2000-10-05
Also published as: AUPP943499A0

Abstract

An intelligent power board for supplying electrical power to a personal computer and a number of computer peripheral devices includes a master outlet (10) into which said computer may be plugged, and slave outlets (12, 14, 16) into which respective peripheral devices may be plugged. The supply of power to the slave outlets (12, 14, 16) is controlled by a switch (22). The power board contains a sensing device (18) which detects whether the computer is switched on or off. A processor (20) processes the information from the sensing device (18) and in response to the nature of that information switches switch (22) on or off, thereby switching on or off the supply of electricity to the outlets (12, 14, 16), which in turn switches on or off the peripheral devices plugged into the outlets (12, 14, 16).

Description

INTELLIGENT POWER BOARD

This invention relates to the provision of electrical power to equipment, and in particular relates to the supply of electrical power to groups of devices or appliances where group components are required to be switched on at the same time.

Most computer users have several peripheral devices connected to their computer, which is usually a personal computer (PC). Such computer peripherals may include a monitor, a printer, an external modem, a scanner, storage devices such as a high capacity disk or tape drive or a recordable CD-RW drive. Each of these peripheral devices has either to be switched on each time the computer is used, with resulting significant inconvenience, or left on permanently, which results in the wastage of an appreciable amount of energy.

US-A-5,548,763 to Combs et al relates to a desk top computer system having multi-level power management. The system, which may comprise a CPU, a monitor, a keyboard, a mouse and a printer, has four states of power management, which are managed by the computer itself. The intention is to reduce energy consumption.

US-A-5,408,668 to Tornai discloses a method and apparatus for controlling the provision of power to computer peripherals. The supply of electrical power is controlled by a microprocessor which instructs a connection circuit to turn a particular peripheral on or off. The microprocessor is able to monitor input signal activity from a peripheral, such if no signal activity is detected, a timer is started. After a predetermined time, the microprocessor instructs the connection circuit to switch off the peripheral.

US-A-5,753,982 by Yeh describes apparatus for supplying power to a peripheral device. The power is supplied from the system power supply via an expansion or standard interface connector. One or two electronic switching devices control the supply to the connector. Each of the aforementioned prior art proposals seems to be an inordinately and unnecessarily complex solution to the management of power supply to a computer and its peripherals.

It is an object of this invention to provide an improved electrical power management system, one which is simpler, does not require any modifications to any of the equipment being controlled, or any skill or overt action on the part of a user.

Power boards (sometimes spelt in the singular "powerboard"), are well known and widely used in Australia. In other countries, power boards are known as "outlet strips" or "power strips". In general, a power board consists of a plug adapted to be plugged into a standard fixed electrical power point (a socket or outlet), which in Australia supplies electrical power at 240V AC at 50Hz/60Hz. The plug is connected to one end of a cable, the other end of which is connected to a housing, normally formed from plastics material, which contains a plurality of outlets.

Conventionally, there are four or six outlets on a power board, although any number may be provided. Electricity is supplied from the fixed power point to the sockets on the power board through the wiring of the plug and the cable. The electrical plugs of appliances are plugged into the sockets of the power board. Normally, such outlets are not switched, although they may be, and often there is a re-settable overload protection mechanism which cuts off the power supply to the outlets when the power board is drawing too much electricity. Some power boards provide more sophisticated surge protection for appliances or the like which are plugged into the power board. In this description and claims, the term "power board" also means "powerboard'. "outlet strip" and "power strip".

Power boards are used domestically where there are a number of separately- powered appliances which are located close together. One example is an audio or audio-visual arrangement, where elements such as an amplifier, CD player, tuner, VCR , television, DVD player, DAT deck, cassette deck and so on are separately powered. In such a situation, a power board is most useful, in that where there would normally not be enough outlets on a conventional power point, and one would be reluctant to use multiple double adaptors, one or more power boards may be used for an electrically acceptable and neat power supply arrangement.

In commercial or industrial situations, and analogous situation arises with the use of PCs and associated peripherals as described hereinbefore. A power board is often used to power those individual elements. It is another object of this invention to provide an intelligent power board which may be used as a conventional power board, but which is also adapted to manage the supply of power to the PC and such peripheral devices.

AU-B-23520/97 (petty patent no, 680398) relates to a "computer controlled power board" for use with PCs and peripheral devices, which power board has a plurality of sockets into which electrical connections of the peripherals may be plugged, and a further connection to the PC. The sockets are connected to a second supply bus, and the PC is connected to a first supply bus, the first and second supply buses being in series, such that when the switch controlling the PC is switched off, the peripheral devices are also switched off. Such a power board could not be described as "intelligent".

It is another object of this invention to provide an intelligent power board which may be used as a conventional power board, but which is also adapted to manage the supply of power to a PC and its peripheral devices.

The invention provides apparatus for the supply of electrical power to at least two units, one of said two units being defined as a master unit and the other or others of said two units being defined as a slave units or as slave units, said apparatus being adapted to be electrically connected to said master unit and to said slave unit or slave units, said apparatus including sensing means adapted to sense the state of said master unit, the state being the said master unit is switched on or switched off, and a switching device for switching power to said slave unit or slave units on or off as a result of the state sensed by said sensing means. Optionally, said apparatus also includes control and/or logic devices for processing the output from said sensing device prior to applying said output to said switching device.

Optionally, said sensing means is a current operated relay.

Optionally, said sensing means and said switching device may be combined, for example by using current operated relay, operated by the current drawn by said master unit, such that said slave unit or said slave units my be switched directly.

Alternatively, said sensing means is a series resistor, or a magnetic field device such as a magneto resistor or a Hall effect sensing element.

Alternatively, said sensing means is driven by a current transformer.

Optionally, said current transformer is adapted to supply electrical power to other components of said apparatus.

Optionally, said apparatus also includes a processor.

Optionally, said processor consist of an amplifier and a driver for said switching device.

Optionally, said switching device is a relay or a triac.

Optionally, said apparatus is a power board, with a master outlet for said master unit, and one or more slave outlets for said or each slave units.

Embodiments of the invention, which may be preferred, will be described in detail hereinafter with reference to the accompanying drawings, in which:

Fig. 1 is a basic circuit diagram of first embodiment of a master-slave or intelligent power board in accordance with the present invention; Fig. 2 is a circuit diagram of a second embodiment of the present invention, a simple practical master-slave or intelligent power board; and

Fig. 3 is a circuit diagram of a third embodiment of the present invention, a more sophisticated, advanced, master-slave or intelligent power board.

The master-slave or intelligent power board of the Figs. 1 , 2 and 3 embodiments of the present invention has a master outlet, preferably in the form of a master socket 10 into which a conventional plug may be plugged. It is intended that a master device (in these embodiments a computer, more preferably a PC (not shown)) be plugged into the master socket 10. Each power board also has at least one slave outlet, preferably in the form of one or more slave sockets; three slave outlets 12, 14, 16 are shown in Fig. 1 (and in each of Figs. 2 and 3). In each figure, the form of the socket is that used in Australia for 240V AC supply at 50Hz/60Hz, and that the three-pin plugs connected to electrical devices (not shown) are complementary; it is to be understood that that form will vary on accordance with the plug/socket designs of the jurisdiction concerned. In addition, in other jurisdictions the supply may be other than 240V, at 50Hz/60Hz.

A slave device or slave devices (in the described embodiments a computer peripheral device or a number of computer peripheral devices (not shown)) is/are intended to be plugged into the slave socket (one of 12, 14, 16), or into a respective one of said slave sockets (12, 14, 16).

The master socket 10 is supplied with electrical power via a sensing unit 18 located in the housing (not shown) of the power board, which sensing unit 18 detects the current drawn by the computer when it is switched on. The power board also includes a processor 20, and a switching device 22, which switching device 22 is turned on by the processor 20 circuitry when the circuitry determines that the computer has been switched on. This is the situation represented by the basic circuit of Fig. 1.

At its simplest, the master-slave power board circuit according to the present invention may consist of a current-operated relay. A current transformer may be used to drive the sensing unit 18, and the operating power derived from transformer output; this would reduce the drop in voltage to the master unit, caused by the sensing device, and reduce the current through the sensing unit to a more convenient level.

The sensing unit 18 may be a small series resistor, a current transformer, a magnetic field sensing device such as a magneto resistor, a Hall Effect sensing element, or any other suitable element. The processor 20 may generally consist of an amplifier and driver for the switching device 22, and preferably a time delay feature, to reduce the surge which might occur if the master unit (outlet) 10 and all the slave units (outlets) (12, 14, 16) were switched on simultaneously, thus improving the reliability of the power board. The switching device may be a relay, a triac, or any other suitable element. As a practical matter, the sample circuit of Fig. 1 would also require a power supply for the various components.

Fig 2 is a circuit diagram of a second embodiment of the invention, a simple practical power board in accordance with the present invention. Low value resistor R1 , connected in series with the lead to one terminal of master socket 10, acts as a shunt to detect the current drawn by the computer (not shown, but in use plugged into master socket 10) when the computer is turned on. Diodes D1 and D2 limit the voltage swing across R1 to about ±1 V.

When the voltage is positive, negative transistor Tr1 is turned on, and when the voltage is negative, transistor Tr2 is turned on, in each case charging capacitor C1 , and causing a current to flow through resistor R3. In turn, this causes a current to flow from transistor Tr3, through resistor R4, into the gate of SCR triac Tr4. This switches on, and energises, slave sockets 12, 14 and 16. When the computer is switched off, or placed in standby mode, the current through R1 falls below the threshold, Tr1 and Tr2 no longer conduct, C1 discharges through R2, and Tr3 and Tr4 switch off, thus switching off the peripheral devices (not shown) which in use are plugged into slave sockets 12, 14 and 16.

Current flowing from the active through capacitor C2 is rectified by diodes D3 and D4 and charges capacitor C3. This provides power for the power board components. D4 is preferably a Zener diode, and keeps the voltage approximately constant. Resistor R5 limits the current flowing through C2, if the power initially switched on at, or near, the peak of the supply voltage waveform.

The third embodiment of a power board according to the present invention, whose circuit is shown in Fig. 3, is more sophisticated than that of Fig. 2. Diodes D1 and D2 and triacs Tr1 and Tr2 detect the current drawn by the computer (not shown, but in use plugged into master socket 10), as described in relation to the Fig. 2 embodiment, and charges capacitor C2. Resistor R3 and capacitor C2 provide an additional time delay to guard against triggering from transient disturbances.

Q1 is one section of a quad 2 input Schmitt trigger Nand logic gate, and is connected as an inverter. When the computer is switched off, the output is low. When the computer is switched on, the output will suddenly switch to +8V, after the delay determined by R3 and C2. Triacs Tr3 and Tr4, and resistors R4 and R5, are connected as a zero crossing detector. Normally either Tr3 or Tr4 is turned on, and the collectors are held low. However, each time the voltage between active and neutral reverses, both transistors are momentarily turned off, causing a brief positive pulse to appear across resistor R5. This positive pulse is applied to one input of Q2, and if the computer is switched on, and the other input is also high, the output of Q2 will go low. This output is connected to the (active low) "Set" input of R-S flip flop Q3, Q4, setting the flip flop. The output of Q4 will be driven low, and will turn on Tr5 and Tr6, as described hereinbefore, applying power to the peripheral devices through sockets 12, 14 and 16.

When the computer is switched off, or placed in standby mode, C2 discharges through R2 and R3, causing the output of Q1 to go low, and resetting flip flop Q3, Q4. As a result, the peripheral devices will be switched off after a short delay.

The purpose of the zero crossing detector is to ensure that triac Tr6 can only be energised when the mains voltage is approximately zero, thereby minimising the resultant current surge as the capacitors in the power supplies of the peripheral devices are charged. In the circuit of Fig. 3, transformer Tx1 charges C3 via D3 and D4, and supplies the operating power for the circuit. It can be seen that the present invention provides and improved apparatus for managing the supply of electrical power to peripheral devices associated with a master unit such as a computer, in particular in the form of an intelligent power board. As has been suggested, the master unit could be something else, such as a television, and the slave unit could be an amplifier used to operate speakers external to the television, for providing sound from the television audio outlet to the speakers. In such an arrangement, a further peripheral could be a VCR, which could also be switched on by the intelligent power board when the television is switched on, to feed (for example) a stereo audio signal to the amplifier to provide a stereo soundtrack for the telecast.

The entire contents of the provisional specification and drawings of Australian provisional patent application no. PP9434, filed on 25 March 1999, are hereby imported into this specification.

The claims form part of the disclosure of this specification.

Claims

1. Apparatus for the supply of electrical power to at least two units, one of said two units being defined as a master unit and the other or others of said two units being defined as a slave units or as slave units, characterised in that said apparatus is adapted to be electrically connected to said master unit and to said slave unit or slave units, and in that said apparatus includes sensing means adapted to sense the state of said master unit, the state being the said master unit is switched on or switched off, and a switching device for switching power to said slave unit or slave units on or off as a result of the state sensed by said sensing means.

2. Apparatus according to claim 1 , characterised in that said apparatus also includes control and/or logic devices for processing the output from said sensing device prior to applying said output to said switching device.

3. Apparatus according to claim 1 or claim 2, characterised in that said sensing means is a current operated relay.

4. Apparatus according to any preceding claim, characterised in that said sensing means and said switching device may be combined, for example by using current operated relay, operated by the current drawn by said master unit, such that said slave unit or said slave units my be switched directly.

5. Apparatus according to claim 1 or claim 2, characterised in that said sensing means is a series resistor, or a magnetic field device such as a magneto resistor or a Hall Effect sensing element.

6. Apparatus according to claim 1 or claim 2, characterised in that said sensing means is driven by a current transformer.

7. Apparatus according to claim 7, characterised in that said current transformer is adapted to supply electrical power to other components of said apparatus.

8. Apparatus according to any preceding claim, characterised in that it also includes a processor.

9. Apparatus according to claim 8, characterised in that said processor consists of an amplifier and a driver for said switching device.

10. Apparatus according to any preceding claim, characterised in that said switching device is a relay or a triac.

11. Apparatus according to any preceding claim, characterised in that said apparatus is a power board, with a master outlet for said master unit, and one or more slave outlets for said or each slave units.