EP0242090A2

EP0242090A2 - Remote reading of a metered quantity

Info

Publication number: EP0242090A2
Application number: EP87302910A
Authority: EP
Inventors: John William Shadrach
Original assignee: Smith Meters Ltd
Current assignee: Smith Meters Ltd
Priority date: 1986-04-17
Filing date: 1987-04-02
Publication date: 1987-10-21
Also published as: PT84720B; GB8609403D0; EP0242090A3; PT84720A; DK192187A; DK192187D0

Abstract

A meter has a liquid crystal (20) on which is displayed the value of a metered quantity, for direct visual reading. A single flashing zone (26) is arranged to display a binary-coded representation of the same value as a timed sequence of flashes. The binary 0's and l's are represented by the presence or absence of flashes.

The flashing code is read by a photo-electric sensor (22) which transmits electrical signals to remote reading station (24). Thus there are no direct connections to the meter.

In an alternative arrangement, fibre optics transmit the flashes of light to a remote station.

Description

The invention relates to the remote reading of a metered quantity, for instance the reading of a gas meter.
Previous methods for remote reading a metered quantity, as described for instance in U.K. Patent No. l,2l3,l25, have used coding devices setting up various electrical coded signals which are then transmitted over electrical wires to remote reading stations. Such methods suffer difficulties due to the complication of the coding and reading arrangements which are expensive and frequently lead to errors.
The present invention comprises a meter adapted for reading at a remote reading station of the kind in which the meter is adapted to present its metered quantity as an electrical signal which may be read at the remote reading station, characterized by means for displaying the electrical signal as a coded sequence of light flashes at the meter, which flashes may be read at the remote reading station.
Specific embodiments of the invention are shown in the accompanying drawings, in which:-

Figure l is a diagrammatic section through a gas meter and remote reading means.
Figure 2 is a representation of the display and remote reading means of Figure l showing further details,
and
Figure 3 is a diagrammatic side view of part of another form of display and remote reading means.

Referring first to Figure l, a gas meter (ll) has a pair of gas chambers, not shown, in which flexible diaphragms work back and forth alternately admitting and exhausting gas through valves. The back-and-forth movements are a measure of the amount of gas passing through the meter, and are transmitted through flag rods (l2) and crank levers (l3) to a common radius arm (l4). Radius arm (l4) rotates shaft (l5) which operates the opening and closing of the valves. A sensor (l7) produces an electrical pulse each time the adjacent radius arm passes it, the pulses being counted by an electronic circuit (l8). The running total of volume of gas passed by the meter is displayed on an electronic display (20), for instance a liquid crystal displaying a decimal number seen best in Figure 2. Battery (2l) powers the electrical items.
Electronic circuit (l8) produces its running total in both decimal and binary coded forms, the decimal form being displayed in decimal numbers on display (20). The binary number is also displayed by a single flashing signal indicator (26). The binary 0's and l's are represented by the absence or presence of flashes of light in a timed sequence. The whole sequence is repeated with gaps between and/or an extra long flash to separate one number from the next. The number cannot easily be read visually, because the sequence is too rapid, but it is detected by a photo-electric sensor (22) which feeds electrical signals along an electric cable (23) to a remote reading station (24). Here the signals may be used to produce a decimal display for visual reading and/or may feed directly into an automatic billing device. The flashing indicator (26) is a part of a liquid crystal display and therefore requires illumination. An electrically powered lamp (27) is mounted beside the photo-electric sensor (22) and directed to energise the indicator (26).
The photo-electric sensor (22) and lamp (27) are both powered from the reading station (24) and do not impose any drain on the meter's own electrical supply. The distance which the reading station can be located away from the meter is limited only by the length of cable (23). Thus the reading station can be at the front gate of a house or at a local centre to which a number of cables from meters are led.
In the alternative remote reading means of Figure 3, a binary-coded signal indicator (26) similar to that described above is used. The display is viewed by a fibre optic cable (30) which transmits light along a core to be detected by a remote photo-electric sensor (3l). Another core of the fibre optic cable transmits light in the opposite direction to energise the indicator (26). Photo-electric sensor (3l) may comprise part of a remote reading station at which the billing function is carried out, or may act as a relay station providing electrical signals representing the binary number to a distant computer or display device.
The signal indicator (26) may, in either example, also convey other coded metering information, e.g. gas temperature, gas flow rate, calibration factors, compensation factors, and/or self checking data, for instance concerning the state of battery (2l), or attempts to interfere with the normal operation of the meter.
By use of these remote reading arrangements a meter buried or partially buried so as to be concealed can be read at a remote location. The meter's own battery-supplied electricity is only used for internal logic and memory functions and a liquid crystal display, all of which have only a low electrical power requirement. Apart from indicator (26), all electrical power required for the transmission of the reading to a remote location is externally supplied.

Claims

1. A meter adapted for reading at a remote reading station of the kind in which the meter is adapted to present its metered quantity as an electrical signal which may be read at the remote reading station, characterized by means (26) for displaying the electrical signal as a coded sequence of light flashes at the meter (ll), which flashes may be read at the remote reading station (24).

2. A meter adapted as claimed in claim l, further characterized by the coded sequence being a binary code in which the presence of a flash represents binary l and the absence of a flash represents binary 0 or vice versa.

3. A meter adapted as claimed in claim 2, further characterized by the coded sequence being repeated cyclically with pauses or other identification signals to indicate the beginning of each sequence.

4. A meter adapted as claimed in any of claims l to 3, further characterized by the means (26) for displaying the light flashes comprising an electrical lamp.

5. A meter adapted as claimed in any of claims l to 3, further characterized by the means (26) for displaying the light flashes comprising a liquid crystal (20), there being also means (27, 30) for directing light at the liquid crystal, the selective reflection of the light from the crystal comprising the light flashes.

6. A meter adapted as claimed in claim 5, further characterized by said meter including a battery-powered electronic circuit (l8) producing electrical signals representing the measure of metered quantity in both decimal and binary-coded forms, the decimal signal being directed to the liquid crystal (20) to produce a display in decimal form, the binary-coded signal being directed to a zone of the same liquid crystal to produce the light flashes, the means (27) for directing light at the liquid crystal producing reflection from both displays.

7. A meter adapted for reading at a remote reading station as claimed in any of claims l to 6, further characterized by reading means comprising a fibre optic cable (30) located to transmit the light flashes.

8. A meter adapted as claimed in any of claims l to 7, further characterized by a photo-electric sensor (22) located to detect the light flashes and directing consequent electrical signals to the remote reading station (24, 3l).

9. A meter adapted as claimed in claim 7, as appendant to claims 5 or 6, further characterized by fibre optic cable means (30) arranged to direct light to the liquid crystal (20) and comprising said means for directing light at the liquid crystal.

l0. A meter adapted as claimed in claim 8, further characterized by both the means for directing light at the liquid crystal display and the photo-electric sensor means being energized from the reading station.