GB2278471A

GB2278471A - Reading meters

Info

Publication number: GB2278471A
Application number: GB9310646A
Authority: GB
Inventors: Martin Robert Pollock
Original assignee: Landis and Gyr Energy Management UK Ltd
Current assignee: Landis and Gyr Energy Management UK Ltd
Priority date: 1993-05-24
Filing date: 1993-05-24
Publication date: 1994-11-30
Also published as: GB9310646D0

Abstract

In order to enable a meter, such as an electricity meter, to be read remotely and also to be read by the human eye, a reading device (20) is provided which is fitted to the front of the meter, which has a bent optical path from the meter register (16) to a sensor (42) to enable the reading device to be compact, and which has a large window or transparent portion (26) to enable substantially all of a faceplate of the meter to be read by human eye. The reading digits are recognised electronically (e.g. at 44) by successive comparisons running down a stored sequence of possible-digit images, so that a match can be obtained even when a meter counter wheel is moving between digit values. <IMAGE>

Description

READING METERS This invention relates, in a first aspect, to the reading of meters such as electricity, gas and water consumption meters, and in a second aspect to the reading of cyclometer registers such as are commonly found in such meters.

Gas and water meters have conventionally been mechanical, and electricity meters have conventionally been electromechanical, both providing a mechanically-moved display which in recent years has commonly been in the form of a cyclometer register. Reading of such meters is a problem, because it requires the employment of people to access and read the meters. Furthermore, if the meter is located inside a building, the meter reader needs to gain access to the building to read the meter, which is not always possible, and if the meter is located outdoors it is subject to the effects of the elements and is liable to be vandalised. Traditionally, a meter reader makes a note of the meter reading on a piece of paper, and then later the reading is keyed into a billing computer for generation of a bill. The meter reader may make a mistake, and the computer operator may make a mistake.

A development of the traditional type of meter is known which provides an output electrical pulse, for example each time a unit is used, and these pulses are transmitted to a central station which counts the pulses. Obviously, this can cause problems if a pulse does not reach the central station for one reason or another.

It has therefore been previously proposed to replace the abovementioned meters with meters which can, as and when required, communicate the complete meter reading via a data link to a central station or if appropriate to a hand-held data collection device. The cost of replacing existing meters with these proposed meters will be extremely high.

A first aspect of the present invention is concerned with finding an alternative solution to the above mentioned problems.

It has been proposed in patent application EP-A-O 279 759 to attach a device to a meter, which can view the register and transmit a signal in dependence upon what is viewed. The device of EP-A-O 279 759 is bulky, and it obscures the front of the meter. An eyepiece is included to enable the register to be viewed by eye, but the device obscures other portions of the front of the meter.

Another reading or monitoring device has been proposed in patent application GB-A-2 148 565. In this device, part-cylindrical lenses are positioned along the left and right edges of the viewing window of meter. The meter dials are illuminated by a light source and a bundle of optical fibres which shine light through one of the lenses to illuminate the dials. In some way or another, reflected light is transmitted through the other lens and another bundle of optical fibres to multiple light sensors which detect movement of the dials. It appears that the meter can be read by the human eye through a window between the lenses, but it is not at all clear that in practice the meter could be read by the device described in GB-A-2 148 565.

The first aspect of the present invention is concerned with providing a practicable solution to the problem of providing a reading device for a meter, and with providing a compact device which also enables the meter to be read by the human eye.

In accordance with the first aspect of the present invention, there is provided a reading device for use with a meter having a housing, a window in the housing, and a register in the housing and viewable through the window, the reading device comprising: a housing adapted to be fitted to the meter housing so as to cover the meter window, the reading device housing having a transparent portion through which the meter window and the register can be viewed by the human eye when the reading device is fitted to the meter housing; an optical system within the reading device housing, including an optical sensor to one side of the reading device housing and means within the reading device housing defining a bent light path from the register to the sensor; and means to transmit data from the optical sensor data representative of the reading of the register.

By bending the light path, a compact device can be provided, and by providing the optical sensor to one side of the reading device housing, there is plenty of room available to enable the register to be viewed by the human eye.

Traditionally the faceplate of a meter includes, in addition to the register, manufacturer and model designations, and certification marks. Also traditional electricity meters have the edge of a disc showing, which rotates as the electricity is consumed. Preferably, the transparent portion of the reading device housing is of sufficient size to enable all, or substantially all, of the faceplate to be viewed by the human eye. Thus, there is no need to remove the reading device to enable these other markings or features to be read.

In one embodiment, the means defining a bent light path includes a beam splitter within the reading device housing so that the light path from the register is split between the light path to the optical sensor and a light path through the transparent portion of reading device housing so that the register can be viewed by the human eye. A mirror may also be included to another side of the housing, and optionally a further mirror to a further side of the housing.

A second aspect of the invention is concerned with a method of reading a cyclometer register.

As is well known, an object can be viewed by an image sensor which produces an electrical signal, and that signal can then be compared with stored signals representing known objects in an attempt to recognise the viewed object. Such a technique could be applied to the digits on the reel of a cyclometer register in an attempt to recognise the reading of the register by comparing the sensed signal with stored signals representing each of the digits 0, 1, 2 ..... 9.

However, with this technique, as the reel rotates from one digit to another, either no match will be found with the stored signals for the ten digits, or a mismatch will be obtained.

In accordance with the second aspect of the present invention, there is provided a method of reading a cyclometer register having a rotatable reel bearing a series of markings, and wherein the reading of the register is as shown by the marking on the reel at predetermined position. and wherein as the reel rotates parts of adjacent markings on the reel can be located at the predetermined position, the method comprising the steps of: producing an image of the register reading on a sensor which produces an image signal; comparing the sensed image signal with each image signal of a stored series of image signals representing the markings on the reel and combinations of adjacent markings as the reading changes from one marking to another; selecting that one of the stored image signals which most closely matches the sensed image signal; and producing a signal in dependence upon which of the stored image signals is selected.

Thus, because the sensed signal can also be compared with stored signals representing parts of adjacent markings, or digits, as the reel rotates, the register can be read more reliably.

In one embodiment, the number of combination marking signals which are stored is substantially greater than the number of stored single marking signals, for example eight times greater. If these signals were all stored separately, a large amount of storage space would be required. For example, if each image signal contains 100 pixels. the storage space required for a reel marked 0 to 9 would be (10 x 10 x 10) + (8 x 10 x 10 x 10), or 9000 pixels. Preferably, the stored series of image signals represents a development of all of the markings on the reels, and the sensed signal can be compared with portions of the stored signal. Comparing this with the example mentioned above, the required storage space is reduced from 9000 pixels to 990 pixels.

Other preferred features of the invention are set out in the appended claims.

A specific embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a reading device fitted to a meter; Figure 2 is a front view of the meter with the reading device shown in outline; Figure 3 is a sectioned view of the reading device and part of the meter, taken along the line 3-3 in Figure 2; Figure 4 shows a sample register reading of the meter and the relationship of an array of pixels to the reading; and Figure 5 shows an example of a template which may be used in recognising the digits of the reading.

Referring to Figures 1 to 3, a conventional electricity meter has a housing 10 with a glazed window 12 in the front thereof. A faceplate 14 is mounted behind the window 12 and bears typical markings such as manufacturers name and model number and certification mark and number. The faceplate 14 also has a first aperture which reveals a line of digits on the reels of a cyclometer register 16 and a second aperture which reveals part of the edge of a wheel 18 which revolves as electricity is being consumed.

A reading device 20 includes a housing having a front part 22 and a rear part 24 secured together. The rear part 24 may be completely transparent. The front part 22 may also be completely transparent or may be textured or coloured so that only a portion 26 thereof is transparent. The rear part 24 has ribs 28 which locate with the edge of the front of the meter, and the reading device 20 also has straps 30 by which the reading device can be secured to the front of the meter, with seals on the straps if desired. When so secured, the transparent portion 26 of the front part 22 of the reading device is aligned with and is about the same size as the window 12 in the meter so that the whole, or substantially the whole. of the faceplate 14 of the meter can be read by the human eye.

An optical system is contained within the reading device. The optical system includes a half-mirrored plane reflector 32 aligned with the register 16 and at an angle of 45 to the vertical, which acts a beam splitter so that the registers can still be read but so that the register reading is also reflected vertically downwardly to a first plane mirror 34 located within the reading device housing near the bottom thereof.

The first plane mirror is inclined at, for example, 34 to the horizontal, and reflects the image of the register 16 sideways to a second plane mirror 36 disposed within the reading device housing near the left-hand side about i of the way up from the bottom. The second mirror is inclined at about 180 to the vertical, and from the second mirror 36, the image of the register is reflected across the housing to a sensor 38 about ; of the way down the right-hand side of the housing.

The sensor includes an imaging lens 40 and an image sensor array 42.

This may be implemented using a charge coupled device (CCD) array or other suitable sensor array. The sensor array 42 forms part of an application specific integrated circuit (ASIC) mounted on a circuit board 44. The ASIC is designed to control and read the image sensor array, to perform the recognition techniques described below, and to transmit the meter reading via a line 45. An infra-red light emitting diode 46 is also mounted on the circuit board 44 adjacent the image sensor array 42 for illuminating the register 16, and the image of the register is transmitted by the beam splitting mirror 32, first and second mirrors 34, 36 and lens 40 so as to be focused on the image sensor array 42.

As shown in Figure 4, the image sensor array 42 may, for example, be an array of 60 cells wide by 10 cells high for a 6 reel register, with 10 x 10 cells for each reel. In a simple form of the embodiment, the sensed image for each reel may be compared with each of ten templates for each of the ten digits 0, 1 ..... 9, and the digit for that reel may be determined to be the digit of the template giving the best correlation. Alternatively, however, in order to enable the register to be read when one or more of the reels is rolling over from one digit to the next, the sensor image for each reel may be compared with a template 48, as shown in Figure 5, which can be thought of as ninety separate templates. The template 48 can be considered to be a development (or flattening out) of the markings on each reel.In the case where, at the image sensor array, there are nine pixel spaces between the top of one digit on a reel and the top of the succeeding digit, the template 44 has ninety nine pixel rows, nine for each of the digits 0, 1 ..... 9 and a further nine rows for a repeated digit 0.

The width of the template may be ten pixel columns, although this may be reduced as, in the example shown, some of the left-most columns and some of the right-most columns are unused. In order to recognise a digit, the 10 x 10 pixel sensed image is compared first with the 10 x 10 pixel block in the template commencing with the first row R1, ie the 10 x 10 block consisting of rows R1 to R10. It is then compared with the 10 x 10 block commencing with the second row R2, ie rows R2 to R11. This process is repeated for each of the eighty-eight 10 x 10 blocks commencing with rows R3 to R9O, and the block with which the best fit is made is determined. The digit is then determined from the commencement row Rx of the best fit block as follows. If 1 s x s 9, then digit 0.If 10 S x 5 18, then digit 1. If 19 s x s 27, then digit 2, and so on up to: if 82 5 x s 90, then digit 9. Alternatively stated, the digit number is the integer part of (x-1)/9.

As shown in Figure 4, the register reading is rolling over between 100229 and 100230. For the "tens" reel, the best fit would be obtained with the 10 x 10 block of the template marked 50 in Figure 5.

The block 50 commenced with row R23, and the digit is therefore recognised as INT((23-1)/9), or 2. For the "units" reel, the best fit would be obtained with the 10 x 10 block marked 52 in Figure 5 commencing at row 87, and therefore the digit would be recognised as INT((87-1)/9), or 9. Therefore, despite the rolling over of the register from 100229 to 100230, the register reading can be read with certainty as 100229.

Data representing the reading is then transmitted via the line 45, for example to the telephone system, or to a remote radio transmitter, or an interrogation module outside the building where the meter is located.

It should be appreciated that the above description is of only one embodiment of the invention and that many modifications or developments may be made thereto. For example, the transparent portion 26 of the reading device housing may be constituted by a separate window. The optical path within the housing may have more or less folds in it. The beam splitter 32 may be provided by a beam-splitting prism, rather than a half-mirror. The output signal on line 45 may represent the series of digits making up the reading rather than the reading as a whole. Alternatively, the signal transmitted on the line 45 may be a bit image signal with recognition being carried out remotely. The circuitry in the device may be arranged to be powered up only when a reading is to be taken, and a reading may be taken at regular intervals, or alternatively when the device is interrogated by a remote device via the line 45.

Claims

1. A reading device for use with a meter having a housing, a window in the housing, and a register in the housing and viewable through the window, the reading device comprising: a housing adapted to be fitted to the meter housing so as to cover the meter window, the reading device housing having a transparent portion through which the meter window and the register can be viewed by the human eye when the reading device is fitted to the meter housing; an optical system within the reading device housing, including an optical sensor to one side of the reading device housing and means within the reading device housing defining a bent light path from the register to the sensor; and means to transmit data from the optical sensor data representative of the reading of the register.

2. A reading device as claimed in any preceding claim for use with such a meter in which the meter window reveals a faceplate having an area substantially greater than that of the register, wherein the transparent portion of the reading device housing is of sufficient size to enable all, or substantially all, of the faceplate to be viewed by the human eye.

3. A reading device as claimed in Claim 1 or 2, wherein the means defining a bent light path includes a beam splitter within the reading device housing so that the light path from the register is split between the light path to the optical sensor and a light path through the transparent portion of reading device housing so that the register can be viewed by the human eye.

4. A reading device as claimed in Claim 3, wherein the means defining a bent light path includes a mirror to another side of the housing.

5. A reading device as claimed in Claim 4, where the means defining a bent light path includes a further mirror to a further side of the housing.

6. A reading device as claimed in any preceding claim, where the optical system includes a light source disposed adjacent the optical sensor and which can illuminate the register via the bent light path.

7. A reading device as claimed in any preceding claim wherein the optical sensor comprises a CCD array.

8. A reading device as claimed in any preceding claim, further comprising means for attaching the reading device to such a meter.

9. A reading device as claimed in any preceding claim for use with such a meter in which the register is a cyclometer register, further comprising recognition means for converting the data produced by the optical sensor.

10. A reading device as claimed in Claim 9, wherein the recognition means is operable to convert the optical sensor data to character data representative of the characters making up the cyclometer reading.

11. A reading device as claimed in Claim 9 wherein the recognition means is operable to convert the optical sensor data to number data representing the number of the cyclometer reading.

12. A reading device as claimed in any of Claims 9 to 11, wherein the recognition means is operable to compare, for each digit of the cyclometer register, an image of that digit obtained by the optical sensor with a series of templates representing each possible digit and combinations of adjacent digits as the register changes from one digit to another.

13. A reading device for a meter, substantially as described with reference to the drawings.

14. A combination of a reading device as claimed in any preceding claim and a meter of the type with which the reading device is specified above to be for use, the reading device being fitted to the meter.

15. A combination of a reading device and a meter, substantially as described with reference to the drawings.

16. A method of reading a cyclometer register having a rotatable reel bearing a series of markings, and wherein the reading of the register is as shown by the marking on the reel at predetermined position, and wherein as the reel rotates parts of adjacent markings on the reel can be located at the predetermined position, the method comprising the steps of: producing an image of the register reading on a sensor which produces an image signal; comparing the sensed image signal with each image signal of a stored series of image signals representing the markings on the reel and combinations of adjacent markings as the reading changes from one marking to another; selecting that one of the stored image signals which most closely matches the sensed image signal; and producing a signal in dependence upon which of the stored image signals is selected.

17. A method as claimed in Claim 16, wherein the stored series of image signals represents a development of the markings on the reel.

18. A method of reading a cyclometer register having a series of rotatable reels each bearing a series of markings and wherein the reading of the register is as shown by the markings on the reels along a predetermined band, and wherein as each reel rotates parts of adjacent markings on that reel can be located in the predetermined band, the method comprising the steps of performing the method of Claim 16 or 17 for each of the reels.

19. A method of reading a cyclometer register, substantially as described with reference to Figures 4 and 5.

20. A reading device as claimed in any of Claims 1 to 13, or a combination of a reading device and meter as claimed in Claim 14 or 15, which is arranged to perform the method of any of Claims 16 to 19.