|1.||Apparatus for converting an analog meter indication of an analog meter having a faceplate and a pointer to an electrical signal comprising: means for illuminating the faceplate and pointer of the meter; light transmitting means for transmitting an image of said faceplate and pointer to a first location, said faceplate being divided into a plurality of discrete areas each corresponding to an indication of said meter; and light sensitive means disposed at said first location for receiving said image from said transmitting means, said light sensitive means comprising an array of a plurality of photosensitive means arranged in a formation corresponding to the shape of said faceplate, each photosensitive means corresponding to a respective one of said discrete areas, said photosensitive means each providing an electrical signal related to the light intensity reflected from a respective discrete area of said meter faceplate, the discrete area in which the pointer is disposed reflecting a substantially different amount of light than said other areas.|
|2.||The apparatus recited in claim 1, further comprising means receiving said electrical signals for providing a plurality of pulses in a code corresponding to said meter indication.|
|3.||The apparatus recited in claim 2, wherein said means for providing comprises means for scanning said plurality of photosensitive means in sequence for providing said pulses in a serial pulse train.|
|4.||The apparatus recited in claim 3 wherein said means for providing comprises motorized stepping switch means.|
|5.||The apparatus recited in claim 3 wherein said means for providing comprises multiplexer means.|
|6.||The apparatus recited in claim 1, wherein said photosensitive means comprise photosensitive semiconductor means.|
|7.||The apparatus recited in claim 1, further comprising^ baffle means for separating the photosensitive means from each other, thereby dividing said array into a plurality of areas corresponding to the areas of said meter faceplate.|
|8.||The apparatus recited in claim 1, further comprising means for supporting said illuminating, transmitting and light sensitive means and for adapting said apparatus to be received in a position opposite said meter faceplate.|
|9.||The apparatus recited in claim 8, wherein said meter comprises a crystal for protecting said meter faceplate and pointer, said crystal being removable and said support means being insertable into an opening in said meter when said crystal is removed.|
|10.||The apparatus recited in claim 1 wherein said transmitting means comprises lens means.|
|11.||The apparatus recited in claim 1, wherein said meter faceplate and array are circular.|
|12.||The apparatus recited in claim 1, further comprising means for switching said illuminating means on when said meter is to be read by electronic reading means coupled to said light sensitive means.|
|13.||The apparatus recited in claim 7, wherein said array is circular and said baffle means are, radially disposed.|
|14.||The apparatus recited in claim 2, wherein said means for providing comprises means for providing a pulse when a photosensitive means receives light energy from said transmitting means and for providing substantially no pulse or a pulse of lesser amplitude when a photosensitive means receives less light energy when said pointer is disposed in an area corresponding to said photosensitive means.|
BACKGROUND OF THE INVENTION
The present invention relates to apparatus for converting analog meter readings to electrical signals, and more particularly, to a device for converting ordinary analog meter dial indications, for example, those of utility meters, such as electric, water and gas meters, amongst others, to electrical or electronic signals, and especially digital electronic signals for transmission over telephone lines to a remote reading device, for example, a remote computer. The present invention allows ordinary analog meters to be read by an electronic device, for example a remote computer, thereby allowing the meter to be read electronically by the remote device instead of requiring a human meter reader to go to the location to physically read the meter dials. An aim of the invention is to provide such an electronic meter reading device preferably such that minimal or no changes are required to the meter itself.
In particular, an aim of this invention is to provide such a meter reading device, preferably such that, at most, only the protective glass viewing cover of the meter be replaced by the device of the present invention.
Various attempts have been made to provide devices for allowing electronic reading of analog meter dials. For example, U.S. Patent No. 3,197,752 to Rabinow, discloses an optical system for remote reading of meters. The apparatus disclosed in that reference utilizes a lens for each meter dial and one photocell for each lens. A scanning disc is provided for each meter dial having a slot therein. A scanning disc is disposed in front of the photocell and is driven by an electric motor. The image of the dial is projected onto the scanning disc. As the scanning disc moves, it will allow light from the white background of the meter to be received by the photocell. When the scanning disc traverses the pointer- of the meter, however, the photocell will momentarily be .in darkness or substantial darkness. Accordingly, the photocell amplifier produces an output signal at this time. The device in the Rabinow patent is complex, as it requires means for synchronizing the signal from the photocell with the position of the scanning disc. Furthermore, due to the use of a scanning disc for each meter dial, only a .single photocell is used for each dial.
U.S. Patent No. 3,778,795 to Campman et al, discloses a remotely controlled apparatus for reading a plurality of
dials in sequence. In the apparatus shown i ~ n the '795 patent, the meter is modified by removing the normal pointer and replacing it with a disk having a nonreflecting coating over substantially its entire surface. Positioned on the disk near its periphery and extending annularly of the disk is a reflecting patch. A plurality of fiber optic light rods are arranged above the disk along with a light source. As the disk rotates, light is reflected to one of the light rods via the reflecting patch, depending upon the position of the disk at a particular point in time. Each of the light rods transmits light energy to a respective photosensitive element. The photosensitive element connects relay contacts into a bank of capacitors, thereby changing the frequency of oscillation of an electronic oscillator. The frequency of oscillation of the oscillator is proportional to the position of the reflective surface on the disk.
Other references relating to this subject matter include U.S. Patent No. 3,930,245 to Taylor, which shows a remote monitor apparatus for meters. The device disclosed in the Taylor reference utilizes a rotating electrical wiper which is affixed to the meter shaft and which makes contact with a spoked conductive wheel which is placed over the meter surface. Accordingly, this reference discloses an electromechanical arrangement for determining the meter position and also requires some modifications to be made to the face of the meter.
U.S. Patent No. 3,840,866 to St. Clair, et al, also
discloses an apparatus for reading a meter which utilizes a wiper contact connected to the meter shaft of each dial which engages respective contacts provided for each of the numerals of the meter dial. The apparatus disclosed in the '866 patent shows two units, one unit being mounted on the meter to be read, and another portable unit, which is brought into proximity with the fixed unit, the fixed unit being accessible, for example, from the exterior of the building via wires. Communication between the portable unit and the fixed unit is accomplished via what the patent calls "radiant energy". In one embodiment, the radiant energy comprises magnetic field coils and in another embodiment, see Fig. 2, light sources and photocells are provided.
Other patents relating to the subject matter of the present invention, include U.S. Patent No. 4,008,458 to Wensley, which uses a magnetic type of pickup to read an analog meter dial; U.S. Patent No. 2,403,889 to Di Toro, which utilizes an inductive type of pickup; U.S. Patent No. 4,296,411 to Romanelli et al, which uses a magnetic pickup; U.S. Patent Nos. 2,176,720 to Rayner et al, 4,204,115 to Boldridge, Jr. and 4,275,393 to Johnston, which show various optical arrangements.
SUMMARY OF- THE INVENTION
It is an object of the present invention to provide a device for converting analog meter indications to electrical signals.
It is yet a further object of the present invention to provide a device for converting analog meter indications to electrical signals which can be read remotely by a remote reading device, for example, a computer.
It is still a further object of the present invention to provide a device for converting analog meter indications to digital electronic signals.
It is yet still a further object of the present invention to provide a relatively simple apparatus for converting analog meter indications to electronic signals, which apparatus preferably requires minimal or no modifications to be made to the meter itself, and which preferably requires no modifications to be made to the meter dial itself.
These and other objects of the present invention are achieved by an apparatus for converting an analog meter indication of an analog meter having a faceplate and a pointer to an electrical signal comprising means for illuminating the faceplate and pointer of the meter, light transmitting means for transmitting an image of the faceplate and pointer to a first location, the faceplate being divided into a plurality of discrete areas each corresponding to an indication of the meter, and light sensitive means disposed at the first location for receiving the image from the transmitting means, the light sensitive means comprising an array of a plurality of photosensitive means arranged in a formation corresponding to the shape of the faceplate, each
photosensitive means corresponding to a respective one of the discrete areas, the photo sensitive means each providing an electrical signal related to the light intensity reflected from a respective discrete area of the meter faceplate, the discrete area in which the pointer is disposed reflecting a substantially different amount of light than said other areas.
Other objects, features and advantages of the present invention will be apparent from the detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail in the following detailed description with reference to the drawings, in which:
FIG. 1 is a side view of one embodiment of apparatus according to the present invention for allowing analog meter indications to be converted to electrical signals;
FIG. 2, which comprises FIGS. 2A and 2B, shows respectively, the face of one meter dial and a corresponding photosensitive array which allows conversion of the analog meter indications to electronic signals;
FIG. 3 shows two analog meter dials and one embodiment of apparatus for converting signals generated by photosensitive elements into electronic signals;
FIG. 4 shows the electronic signals generated by the apparatus of FIG. 3; and
FIG. 5 shows an alternative embodiment of apparatus for converting signals generated by the photosensitive elements into electronic signals.
With reference now to the drawings, FIG. 1 shows schematically apparatus according to the present invention for converting analog meter indications to electrical signals. A meter dial faceplate of an existing meter 5, for example, an electric or water utility meter, is shown by reference numeral 10. The pointer of the meter dial is indicated by reference numeral 12 and is connected to the meter movement 13 by shaft 15. In one embodiment, the typical glass or ■ plastic viewing cover or crystal of the meter is removed, and in its place, the apparatus of the present invention is disposed. Accordingly, the apparatus of the present invention may be made so that it fits into the space formerly occupied by the meter crystal.
Suitable fasteners or adhesive can be used to secure the apparatus of the present invention to the meter. This is shown schematically by the support 7, shown in partial cross section, on which the apparatus of the present invention is constructed. Alternatively, the ' apparatus of the present invention may be made such that the meter crystal need not be removed. In such an embodiment, the support 7 for the apparatus of the
present invention can be securely attached to the meter crystal or bezel by suitable attaching means, such as fasteners or adhesive. The apparatus of the present invention includes a light source 14 mounted to support 7, a lens 16, and an array of photosensitive means 18, such as photodiodes, LED's, photocells or phototransistors. A typical meter dial is shown in front view in FIG. 2A, and the array of photosensitive means facing the meter dial is shown in FIG. 2B. As shown in FIG. 2B, the photosensitive means 20 may be arranged in a circle, conforming to the circular arrangement of the meter dial. If the meter dial is not circular in shape, but of some other shape, then the photosensitive array 18 would be correspondingly shaped. In the embodiment shown in FIG. 2, however, the photosensitive means 20 are arranged in a circular array. A series of radial baffles 22 separating the circular array into a series of sectors, isolates each . photosensitive means 20 from the others. Accordingly, lens 16 projects light reflecting off meter faceplate 10 onto the photosensitive array. Generally, the meter faceplate 10 comprises a white background whereas the meter pointer 12 contrasts with the white faceplate 10, and is usually black. Accordingly, light reflected off the faceplate 10 will be transmitted by lens 16 to the photosensitive array 18. Less light, however, will be reflected from the sector in which the pointer 12 is disposed, and accordingly, less light will appear in the corresponding sector of the photosensitive array 18. This is shown by the cross-hatched lines in FIG. 2B in one sector. Accordingly, one photosensitive means will
receive less light than the other photosensitive means. It is to be understood that the invention can also be applied to the situation where the faceplate is dark and the pointer light.
Since typically utility meters have a number of meter dials per meter, an individual lens 16 will be required for each dial to focus the dial image on an individual array of photosensitive means 20 connected with that lens. For each dial, as mentioned, the dial sector in which the pointer 12 is positioned will project a lower light intensity on its corresponding photosensitive means than will the other sectors. As shown in FIG. 3, in one embodiment, one terminal of each photosensitive means 20 in each array is coupled to a common point, e.g., ground. A motorized stepping switch, shown by wiper contact 30, can be provided to make electrical contact with each of the ten photosensitive means provided for each meter dial. Instead of a motorized stepping switch, a multiplexer can also be used, in which case the 10 leads from the 10 photosensitive means in each array would be provided to a multiplexer, which preferably would convert the signals appearing on the 10 leads in each array into serial data, as shown in FIG. 4. In the embodiment shown in FIG. 3,-'a power source 32 and resistor 34 are coupled in series and connected to the stepper switch wiper arm 30 and to ground. Accordingly, as the motorized stepper switch traverses the contacts 36, a pulse will be produced for each contact across terminals 38 and 40, the pulse being related (or alternatively inversely related) to the
amount of light received by the corresponding photosensitive means 20. As shown in FIG. 3 by the meter dial 10a, the pointer 12 is positioned in the "4" sector. The pointer ' of meter dial 10b is positioned in the "1" sector. Signals will be developed across contacts 38 and 40 related to the amount of light received by the respective photosensitive means. For example, for meter dial 10a, in sectors "1", "2" and "3", and if photodiodes are used, the photodiodes will be conducting because light is being received in those sectors. Accordingly, a current will flow through resistor 34, producing a potential difference across contacts 38 and 40 when wiper, arm 30 traverses the contacts for sectors "1", "2" and "3". In sector "4", however, less light is received due to the pointer 12a, and accordingly, the photodiode will be in a nonconducting state or if a photocell is used, e.g., a cadmium sulfide photocell, the resistance will be increased. Accordingly, substantially no pulse or a pulse of lesser amplitude will appear across contacts 38 and 40, as shown in FIG. 4. Similarly, for meter dial 12b, less light will be received in sector "1", as shown in FIG. 4. The number "41" is thus read by the remote reading device.
In an alternative embodiment, the photosensitive means might comprise selenium photocells, in which case the voltage generated by the photocell will be proportional to the light energy received.
Should the pointer 12 be in a position such that it is
-li¬ on the border between two sectors, then less light will be received in two sectors of array 18, thereby causing two photosensitive means to receive lower light intensity. Accordingly, in the embodiment shown in FIG. 3, a pulse of lesser amplitude will appear twice in the pulse train corresponding to one meter dial. Such ambiguous readings can be resolved by the reading device, for example, the remote computer, by programming the computer to examine succeeding sectors to determine whether the succeeding dial pointer is in the 9 sector or the zero sector, as would normally be done by a human reader.
Furthermore, although photodiodes have been shown as the photosensitive means, other light sensitive devices may be used, for example, as mentioned, photocells. A cathode ray* tube or space charge coup'led device may also be used in lieu of photodiodes to receive the images of the dial pointers. The images are then scanned electronically to produce a digital output.
As shown in FIG. 3, a photosensitive array 18 is provided for each meter dial of the meter, and the outputs of the photodiodes in each photosensitive array are scanned in succession. For example, if there are five meter dials, five successive trains of 10 pulses will be outputted by the apparatus of FIG. 3. These signals can be transmitted over telephone lines, for example to a remote device, or can be converted by further electronic components into a weighted binary code, for example, a 4-bit binary code.
In order to conserve energy, light source 14 may be provided so that it can be turned on by the remote reading device only at that point in time when the meter is to be read.
FIG. 5 shows an alternative embodiment of apparatus for scanning the photosensitive means for two meter dials. Signals from the photosensitive means of arrays 18a and 18b are fed to a first bank 41 of electronic switches. The outputs of electronic switches 41 are coupled to a multiplexer 42, which produces a serial output. A clock signal is fed to multiplexer 42 and the clock signal divided by ten is fed to electronic switches 41. Accordingly, electronic switches 41 couple signals from one array while all ten photosensitive means in that array are scanned by multiplexer 42. After ten clock ^.. pulses, electronic switches 41 switch to the other array and multiplexer 42 then scans all ten photosensitive means of the other array before the first array (or a succeeding one) is scanned.
In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.