GB2239747A

GB2239747A - Data protection device

Info

Publication number: GB2239747A
Application number: GB9000013A
Authority: GB
Inventors: Philip Ormrod
Original assignee: GOTEC RESEARCH AND DEV Ltd
Current assignee: GOTEC RESEARCH AND DEV Ltd
Priority date: 1990-01-02
Filing date: 1990-01-02
Publication date: 1991-07-10
Anticipated expiration: 2010-01-02
Also published as: GB9000013D0; GB2239747B

Abstract

A data protection device is connected to a computer or other data processing device which receives power from an uninterruptable power supply. The protection device provides a warning signal to software of the computer if the uninterruptable power supply is switched from mains to a battery power supply, and a signal indicating when the batteries are likely to run below an unacceptably low level. Such a signal will allow the software shut-down in the appropriate manner without loss of data. A circuit 2 includes a relay K1 responsive to indicate mains or battery supply. A circuit 4 has a comparator IC1 which indicates a low voltage from standby battery 6. The circuits 2, 4 are coupled to the computer by sockets 11, 12. <IMAGE>

Description

A Data Protection Device The present invention relates to protection of data which is being handled by a computer receiving power from an uninterruptable power supply.

A large proportion of errors in processing or handling of data in electronic devices such as computers, word processors, telephone equipment, process control and point of sale equipment are caused by disturbances in the mains power supply. Such disturbances may take the form of voltage spikes, over or under voltage levels, interruptions and complete failure. To guard against such problems, stand-by or uninterruptable power supplies are often used for delivery of power to such electronic devices. In normal operation, the uninterruptable power supply will re-transmit the mains supply and simultaneously re-charge batteries. If the mains supply fails, the batteries will provide power, but only for a limited time period which generally varies between ten minutes and one hour, depending on the load.

One problem with such presently available power supplies is that they do not in use distinguish between the requirements of a load, for example, the requirements of an electric motor may be different from that of a computer, in which latter case there would be a much smaller tolerance range for the voltage supply. Consequently, at a certain time after mains failure the supply from the battery will drop below a threshold level at which data will be corrupted in a computer or other data processing device.

The present invention is directed toward providing a data protection device for computers to overcome these problems.

According to the invention, there is provided a data protection device for protection of data handled by a computer receiving power via an uninterruptable power supply, the protection device comprising: a protection device power supply circuit comprising a parallel connection of a capacitor and a zener diode arranged to be connected across the battery output of the uninterruptable power supply; a mains status detection circuit comprising a two pole relay for connection with the uninterruptable power supply to provide a signal indicating whether mains or stand-by power is being delivered to the computer;; an uninterruptable power supply battery monitor circuit comprising a voltage reference circuit fed by the protection device power supply, a battery voltage sense circuit, a comparator connected to the voltage reference and sense circuits and connected at the output to a battery monitor relay; and an output socket connected to the mains status and the battery monitor relays for delivery of mains status and battery voltage level indicating signals to the computer to enable shut-down of software running on the computer before the battery voltage drops to an unacceptably low level.

In one embodiment of the invention the voltage sense circuit includes a potentiometer in series with a fixed resistor connected across the battery output for variation of the trip voltage for the battery of the uninterruptable power supply.

Ideally, the battery monitor circuit includes a light emitting diode for indicating voltage level of the battery.

According to another aspect, there is provided an uninterruptable power supply incorporating a data protection device as claimed in any preceding claim.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, given by way of example only with regard to the accompanying drawings which is a circuit diagram of a computer data protection device of the invention.

Referring to the drawing, there is illustrated a computer data protection device according to the invention indicated generally by the reference numeral 1. The protection device 1 is for protection of data handled by a computer or other electronic device. This is achieved by indicating when software shut-down procedures should begin prior to the end of useful battery operation of an uninterruptable power supply for the computer.

The protection device 1 includes a mains status detection circuit 2 comprising a relay K1 for connection at an input socket 3 to an uninterruptable power supply. The relay K1 is of the two-pole type. The protection device 1 also includes a a battery monitor circuit 4 connected at an input socket 5 to a battery 6 of the uninterruptable power supply. The socket 5 connects with a negative lead 7 and two positive 8 and 9 having a common switch 10. The positive lead 9 includes a resister RE. The mains status detection circuit 2 and the battery monitor circuit 4 are connected to an output socket 11 having six leads. The output socket 11 connects with a computer via a single pin socket 12 having an upper portion 12a an intermediate portion 12b and a lower portion 12c.

The battery monitor circuit 4 includes a power supply formed by an electrolytic capacitor C1 and a zener diode Z1 connected across the battery 6 output at the negative lead 7 and the positive lead 9. The battery monitor circuit 4 also includes a comparator formed by an operational amplifier IC1, feedback resistors R3, R5 and R6 and a feedback diode D2. The inputs of the operational amplifier IC1 are provided by a reference circuit formed by resistors R2 and R4 and a zener diode Z2.

The other input is from a sense circuit formed by a parallel arrangement of a potentiometer P1 and a capacitor C2 connected in a series to a resistor R1, the circuit being connected across the negative lead 7 and the positive lead 8 of the battery 6. The potentiometer P1 is variable to adjust a trip voltage for the comparator. The output of the operational amplifier IC1 drives a relay K2, which is in turn connected to the output socket 11. The relay K2 is energised during normal operation and is de-energised when the battery voltage drops below a pre-determined trip level.This trip level is set by the potentiometer P1 in accordance with the circumstances, including the type ofuninterruptable power supply being used, the power requirements of the computer being supplied and the processing time of software in the computer being supplied.

The important parameter is the length of time required by software of the computer to carry out all of the shut-down procedures without loss of data before the battery voltage drops to an unacceptably low level.

The output socket 11 includes leads 2 and 5 which are common to both relays K1 and K2 and this is represented as the upper portion 12a of the plug 12. The intermediate portion 12b provides an indication from the relay K2 of status of the battery and the lower portion 12c provides an indication from the relay K1 of the mains status. A link L1 or a link L2 may be used for the common leads 2 and 3.

The battery monitor circuit 4 also includes a light emitting diode L.E.D. which is switched on by the relay K2 when the battery voltage drops an unacceptably low level.

It will be appreciated that the invention provides a device which is relatively simple to operate and to adjust to the circumstances required for protection of data handled in the data processing system. The device may be connected to any type of uninterruptable power supply and all that is required at the computer or data processing system being supplied is that the software should recognise the signals supplied by the protection device and take appropriate action. It is envisaged that the protection device may be connected to an alarm device for indication to users that the software is required to shut-down in organised manner.

The data protection device of the invention may be incorporated in an uninterruptable power supply.

Claims

1. A data protection device for protection of data handled by a computer receiving power via an uninterruptable power supply, the protection device comprising: a protection device power supply circuit comprising a parallel connection of a capacitor and a zener diode arranged to be connected across the battery output of the uninterruptable power supply; a mains status detection circuit comprising a two pole relay for connection with the uninterruptable power supply to provide a signal indicating whether mains or stand-by power is being delivered to the computer; an uninterruptable power supply battery monitor circuit comprising a voltage reference circuit fed by the protection device power supply, a battery voltage sense circuit, a comparator connected to the voltage reference and sense circuits and connected at the output to a battery monitor relay; and an output socket connected to the mains status and the battery monitor relays for delivery of mains status and battery voltage level indicating signals to the computer to enable shut-down of software running on the computer before the battery voltage drops to an unacceptably low level.

2. A data protection device as claimed in Claim 1, wherein the voltage sense circuit includes a potentiometer in series with a fixed resistor connected across the battery output for variation of the trip voltage for the battery of the uninterruptable power supply.

3. A data protection device as claimed in Claims 1 or 2, wherein the battery monitor circuit includes a light emitting diode for indicating voltage level of the battery.

4. A uninterruptable power supply incorporating a data protection device as claimed in any preceding claim.

5. A data protection device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.