Abstract:
A meter reader for reading a meter have a display portion displaying a total output of a quantity being metered and plural incremental outputs defining the total output. The meter reader includes a sensing mechanism for sensing one of the plural incremental outputs in the meter display portion, and a processing unit coupled to the sensing mechanism for accumulating incremental outputs sensed by the sensing mechanism and for determining accumulated meter output over a time period based on the accumulated incremental outputs. Also included is an output mechanism for outputting the accumulated meter output determined by the processing unit. In one example, the sensing mechanism includes a sensor for sensing only a least significant incremental output in usage included in the meter display portion, and an emitter for illuminating the least significant incremental output included in the meter display portion. Further, the sensing mechanism senses the least significant incremental output included in the meter display portion at least once every full cycle of the least significant incremental output.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to automated meter reading, and more particularly to a meter reader including a sensor for sensing only a least significant incremental output in usage included in a meter display portion. 
     2. Discussion of the Background 
     Modem households are powered by electricity, gas and water, etc. The household receives electricity from the electrical company, in many cases a public utility. Similarly, natural gas is supplied by a gas provider, and water is supplied by the water commission. 
     The consumption of electricity, gas and water is measured by meters which have been installed at the customer&#39;s house. For example, the electricity meter measures the amount of electricity (i.e., power) used by the household and the consumption of electric power is indicated by readings on the meter. The electrical meter typically includes a number of dials which show the power consumption in Kilowatt hours. To bill the customer, it is necessary for the electrical utility to obtain a power consumption reading from the meter. Therefore, before the electrical utility can issue bills to its customers, the electrical meters at each house must be manually read. This represents a significant expenditure of manual effort. The situation is further exacerbated by the inaccessibility of some meters, e.g., located inside the basement of a house, and the unavailability for reading during normal working hours when the occupants of the house are not at home, but are at work. 
     To contain costs and enhance a competitive position in the utility market place, many utility companies are investigating and implementing automated meter reading capabilities. For example, background automated meter reading solutions sense the current consumption by physically coupling a sensing device to the rotation of the display dials, magnetically coupling the sensing device to the meter, or electrically coupling the sensing device to an LCD or other type of display. 
     However, in all of these cases, the sensing device must be physically placed within the electrical meter housing (i.e., under the glass covering). This requires an extremely labor-intensive process of retrofitting the meters. This retrofitting process also has a potential of damaging the meter. 
     Further, other background meter reading devices capture an image corresponding to the entire meter display portion (i.e., all display dials) and transmit this entire image for processing. This increases the battery consumption used by the meter reader and requires complicated circuitry. 
     In addition, the background devices only fit one particular type of meter and therefore several different types of meter readers are required. Thus, the background meter reading devices are generally expensive to implement, maintain and repair. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to solve the above-noted and other problems. 
     Another object of the present invention is to provide a novel meter reader that does not require an extensive retrofitting process. 
     Still another object of the present invention is to provide a novel meter reader than can be used with a variety of meters from various venders under all environmental conditions. 
     Yet another object of the present invention is to provide a novel wireless meter reader that can transmit metering information to a radio receiver, from which a utility company can gather and process the transmitted information. 
     Another object of the present invention is to provide a low-cost meter reader that is simple to implement, maintain and repair. 
     To achieve these and other objects, the present invention provides a novel meter reader for reading a meter having a display portion displaying a total output of a quantity being metered and plural incremental outputs defining the total output. The meter reader includes a sensing mechanism for sensing one of the plural incremental outputs in the meter display portion, and a processing unit coupled to the sensing mechanism for accumulating incremental outputs sensed by the sensing mechanism and for determining accumulated meter output over a time period based on the accumulated incremental outputs. Also included is an output mechanism for outputting the accumulated meter output determined by the processing unit. In one example of the present invention, the sensing mechanism includes a sensor for sensing only a least significant incremental output in usage included in the meter display portion, and an emitter for illuminating the least significant incremental output included in the meter display portion. Further, the sensing mechanism senses the least significant incremental output included in the meter display portion at least once every full cycle of the least significant incremental output. The present invention also relates to a method and computer program product for reading a meter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIGS. 1A and 1B  illustrates a first example of reading a meter according to the present invention; 
         FIG. 2  illustrates a second example of reading a meter according to the present invention; 
         FIG. 3A  illustrates a comparator according to the present invention for reducing an image captured by a camera to one bit per pixel; 
         FIG. 3B  is a pictorial diagram illustrating an example of pixel values that are extracted from the captured image and converted to bit values; 
         FIG. 4A  illustrates a circuit for generating differential video information according to the present invention; 
         FIG. 4B  is a pictorial diagram illustrating the generation of the differential video information according to the present invention; 
         FIG. 5  is a pictorial diagram illustrating edge-detection data from two separate image scans according to the present invention; 
         FIG. 6  is an overview illustrating in more detail the components included in the meter reader according to the present invention; 
         FIG. 7A  is an overview illustrating the meter reader being externally mounted to the meter according to the present invention; 
         FIG. 7B  is a side view of the meter reader shown in  FIG. 7A ; 
         FIG. 8A  is an overview illustrating a series of photo cells with a parallel capacitor as a first alternative for powering the meter reader according to the present invention; 
         FIG. 8B  is an overview illustrating another alternative for powering the meter reader according to the present invention; 
         FIG. 9  is an overview illustrating another example of a meter reading according to the present invention; 
         FIGS. 10A and 10B  are overviews illustrating transmission and reception aspects of the meter reading according to the present invention; 
         FIGS. 11A and 11B  are pictorial diagrams illustrating how to properly install and align the electric meter according to the present invention; 
         FIG. 12  is a pictorial diagram illustrating how an image processing algorithm compensates for possible alignment errors with the meter reading according to the present invention; 
         FIG. 13  is an overview illustrating a preferable depth of field for the meter reader according to the present invention; 
         FIG. 14A  is a circuit illustrating a hardware based light dark differentiator circuit; 
         FIG. 14B  is an overview illustrating mounting of detector and optics to view hands on meter dial; 
         FIGS. 15A-15C  illustrate adaptive filtering methods according to the present invention to correct glass imperfections and other obstructions with the meter; 
         FIG. 16  illustrates a Kalman filter prediction method according to the present invention; 
         FIG. 17  is a pictorial diagram illustrating how the predictable movement of the meter dial can advantageously be monitored by a sensor according to the present invention; 
         FIG. 18  is a pictorial diagram illustrating the sensor mechanism according to the present invention tracking the number of times a dial hand has crossed a certain point on the dial face; 
         FIG. 19  illustrates one example of the present invention to overcome alignment problems; and 
         FIG. 20  illustrates how an optical sensor can be used to read a dial hand according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, the present invention will be described. 
     Turning first to  FIG. 1A , this figure illustrates a first example of optically reading a meter according to the present invention. In this example, a meter reader according to the present invention includes a light emitter  8  and a light receiver  10 . The light emitter  8  emits light towards a rotating disk  4  included in the electric meter. Light reflected from the rotating disk  4  is received by the light receiver  10 . Note that in this example the user&#39;s current consumption (e.g., metering data) is determined from the rotating disk  4  and not the plurality of dials  2  accompanied with the meter. Also note the rotating disk  4  generally includes a single mark  6 . 
     Thus, as the disk  4  rotates, the optical receiver  10  receives a varying amount of light. For example,  FIG. 1B  illustrates an example of different brightness levels the light receiver  10  measures as the disk  4  makes a single revolution. These brightness values may be used to determine the amount of power provided to the customer as brightness values above or below a predetermined threshold value may be used to denote a single revolution of the disk  4 . 
       FIG. 2  illustrates a second example of optically detecting metering data according to the present invention. In this example, only a least significant incremental output (e.g., least significant dial) of the meter is read. In more detail, as shown in  FIG. 2 , an illuminating emitter  20  (such as an infrared LED) is disposed over a center of a least significant dial  27 . Further, a plurality of sensors  24 ,  26 ,  28 , etc. are disposed around a circumference of the least significant dial  27  at locations corresponding to count numbers on the least significant dial  27  (i.e., count numbers  0 ,  1 ,  2 ,  3  . . .  11 ). In this example, it is preferable the emitter  20  is positioned directly over the center portion of the least significant dial  27  so as to illuminate the entire dial  27 . 
     The plurality of sensors  24 ,  26  and  28 , etc. may then be used to determine the position of a dial hand  22  based on a difference of reflections of light from the emitter  20 . For example, the meter reader according to this example may determine that the dial hand  22  is at the count number  0  because the sensor  28  receives significantly less light reflection from the emitter  20  (i.e., because the dial hand  22  is passing thereunder). A processing unit may then process the information sensed by the sensor  28  along with a previous reading so as to determine the amount of power used by the customer. 
     In another example, it is also possible to concentrate on the sensor that will most likely detect the presence of the dial hand  22 . For example, as shown in  FIG. 2 , if the dial hand  22  is moving in a counterclockwise direction (as shown by the arrow in the drawing) and it is known the dial was just currently sensed by the sensor  24  (as shown by the dash dial hand  22 ′), the processing unit can concentrate on sensors  26  and  28  and ignore the other sensors or pay less attention to them so as to further reduce the amount of required processing (and accordingly reduce the amount of battery consumption required to operate the meter reader). 
     Thus, because only the least significant dial is monitored according to the present invention, the size of the image captured is significantly reduced compared to that of the background type meter reading devices. That is, as discussed above, the background devices capture and process an image corresponding to all of the dials. This increases the amount of processing equipment required for the device, as well as the amount of battery consumption by the device. On the contrary, the present invention is significantly able to reduce the amount of battery consumption, the complexity of the device, and provide accurate information about the customer&#39;s usage by reading only the least significant dial. Further, the sensing mechanism (i.e., sensors  24 ,  26  and  28 , etc.) are configured to sense the least significant dial  27  at least once every full rotation of the least significant dial  27 . Therefore, the amount of power delivered to the meter is properly read. 
     Another example of reducing the battery consumption and complexity of the device is shown in  FIGS. 3A and 3B . In more detail,  FIG. 3A  illustrates a comparator  36  according to the present invention for reducing an image captured by a camera to one bit per pixel, and  FIG. 3B  is a pictorial diagram illustrating an example of pixel values that are extracted from the captured image and converted to bit values. In this example, rather than using a plurality of sensors  24 ,  26 ,  28 , etc. as shown in  FIG. 2 , the sensing mechanism includes a camera (such as a CCD camera or a CMOS sensing camera) for capturing an image of the least significant dial. The comparator  36  then reduces the image captured by the camera to one bit per pixel. 
     That is, an average gray-level value  32  is first determined for an entire image. The average gray-level value  32  may change according to ambient light conditions, which ensures that the present invention properly functions over all ambient light conditions. As shown, the average value  32  is used as the negative input to the comparator  36  and the picture stream is input into the input  38  of the comparator  36 . Then, at an output  40  of the comparator  36 , each pixel is set to be either black or white (i.e., the minimum output voltage or maximum output voltage of the comparator, respectively). Thus, the captured image is reduced to one bit per pixel (i.e., a 0 or a 1). This feature is clearly illustrated in  FIG. 3B . 
     In more detail, the pixel samples  42 ,  44 ,  45 , etc. are input into the input  38  of the comparator  36 . As shown, the output bit value remains at 0 until the pixel sample  44  is input. Because the pixel sample  44  includes mostly a black value in relation to the present gray-level value  32 , the output bit value is increased to 1. Thus, because the captured image is reduced to one bit per pixel, the battery usage required to operate the meter reader according to the present invention is further reduced. 
       FIGS. 4A ,  4 B and  5  illustrate yet another example of further reducing the required battery usage for operating the meter reader according to the present invention. In these figures, the present invention performs an edge-detection algorithm to reduce the image captured by the camera to one bit per pixel. The present invention may then perform a difference calculation on subsequent images to determine the amount of power used by the consumer. In more detail,  FIG. 4A  illustrates a circuit  46  which may be used to perform the edge-detection method according to the present invention. The circuit  46  includes an amplifier  48  having an input  56  and output  50 , a capacitor  52 , and a resistor  54  connected to ground. The pixels of the captured image are input to the input  56  of the circuit  46  and a bit value is output via the output  50 . This feature is clearly illustrated in  FIG. 4B . Note  FIG. 4B  differs from  FIG. 3B  in that the bit value for the pixel  45  is 0 and not 1 as in  FIG. 3   b . This is because the circuit  46  according to the present invention performs an edge-detection algorithm and only the edges are set to a bit value 1, for example. That is, a bit value is set to be 1 if and only if a respective pixel value is greater than the gray-level value and a previous pixel value was less than the gray-level value. 
     The edge detection algorithm is further illustrated in  FIG. 5 . As shown, the captured image of the least significant dial is a 64×64 bit image. Note also that two positions of the dial hand are shown in  FIG. 5 . That is, the dial hand  22 ′ shows the position of the dial hand during a first reading of the meter and the dial hand  22  shows the subsequent reading of the meter (similar to the dial hands  22  and  22 ′ shown in  FIG. 2 ). As shown, the edge-detection algorithm sets all values to 0 other than the edges of the dial hand  22  and  22 ′, which are set to 1. Note, however, that noise  60  does occur in the image and these values will also be converted to a bit value of 1. These values may be easily ignored as they do not contribute to a shape of the dial hands  22 ,  22 ′. Thus, as clearly shown in  FIG. 5 , the present reading of the meter may be easily accomplished by performing a difference calculation on subsequent images (the differences between the dial hands  22  and  22 ′). This technique is particularly advantageous in that degraded image sensors resulting in bad pixels will not effect the overall performance of the meter reader. Alternatively, the edge-detection algorithm could simply transmit the change from the last image, which retrieves the movement of the hands, but eliminates any static information (i.e., both images would not have to be transferred—only the change from the last image is transferred). 
     Turning now to  FIG. 6 , which is an overview illustrating in more detail the components included in the meter reader according to the present invention. As shown, the meter reader  75  according to the present invention includes a radio transmitter  80 , a power unit  78 , a camera  76  (such as a CCD camera), a lens  72  and an infrared LED  74 . The infrared LED  74  illuminates a display portion  71  of a meter  62  having usage dials  64 ,  66 ,  68  and  70 . Note according to the present invention, only the least significant dial  64  is captured by the meter reader  75 . Thus, as discussed above, accurate metering data can be obtained according to the present invention, while at the same time reducing the amount of battery consumption. 
     Turning now to  FIGS. 7A and 7B , which are an overview illustrating the meter reader being externally mounted to the meter and a side view of the meter reader, respectively. In more detail, as shown in  FIG. 7A , the meter reader  75  is mounted to an external surface of the meter  62  via a mounting mechanism  118 . Further, the meter reader  75  is positioned over the least significant dial  64  so as to sense information only about the least significant dial  64 . The mounting mechanism  118  may also include a mounting strap equipped with a pressure switch so as to serve as a temper detection mechanism, for example. The tamper detection sensor may be a pressure sensitive switch, a reflective sensor, reed switch and magnet or other means to detect that the RF module has been removed from the meter. The coupling mechanism  118  may also include an inductive coupling mechanism (such as coil wires wrapped around the external surface of the meter  62 ) for capturing electric field magnetic radiation from the meter  62  and converting the captured radiation to power for the meter reader  75  (this feature is discussed in more detail with reference to  FIG. 8B ). In addition,  FIG. 7B  illustrates a side view of the meter reader  75  showing the lens  72  positioned to receive light reflected from the least significant dial  64  and to be captured by the camera  76 . 
     Additionally, the power unit  80  illustrated in  FIG. 6  may include rechargeable battery cells to provide power to the meter reader  75 . Alternatively, as shown in  FIG. 8A , the power unit  80  may include a series of photo cells  102  in parallel with a capacitor  104  to provide power to the meter reader  75 . In addition,  FIG. 8B  illustrates yet another alternative of the power unit  80  in which coil wires  162  are wrapped around the external surface of the meter  62  to capture electric magnetic field radiation from the meter so as to provide power to the meter reader  75 . That is, the coil wires  106  extract electromagnetic field radiation from the meter  62  which is then impedance matched in the impedance matching circuit  108 . The voltage then passes through a diode  110  for supplying power to the meter reader. Also shown is a Germanium/Schottkey  116 . 
     Turning now to  FIG. 9 , which is an overview illustrating yet another example of a meter reader according to the present invention. In this example, the meter reader reads two least significant dials  82  and  84  (rather than just one least significant dial). As shown, the meter reader includes a lens  86  associated with the sensing mechanism  92  (e.g., a CCD camera), and a processing unit  96  having a CPU  98  and a Random Access Memory (RAM)  100 . The least significant dials  82  and  84  are illuminated by an LED  94  and light reflected off the dials  82  and  84  is captured via the lens  86  and CCD camera  92 . The processing unit  96  then processes the information sensed by the sensing mechanism  92  so as to determine the amount of power used by the consumer. Further, a depth of field  88  between the lens  86  and optical surface  90  of the CCD camera  92  is set to ensure the proper tolerance such that the least significant dials  82  and  84  are accurately read. 
     Turning now to  FIGS. 10A and 10B , which will be used to illustrate an overall operation of a meter reading system according to the present invention. As shown in  FIG. 10A , an LED  94  illuminates a display portion of a meter. In this example, the display portion may include an LCD  84 , a mechanical dial  82  having a dial hand, or a series of mechanical dials  80  rotating on a same axis. The sensing mechanism including a lens  86  and camera  88  is used to sense information about the dial. A processing unit (not shown) processes the information sensed by the sensing mechanism so as to determine the amount of power used by the consumer. The meter reader also includes a transmitter  90  with an antenna  92  for transmitting the metering data to a centralized location for further processing. The transmitter  90  may format the image data into an on-air message and transmit this data to a receiver  100  including an antenna  98  (see  FIG. 10B ). The received image may then be formatted as necessary by a processor  102  and displayed on a display  106 . Further, the processor  102  may utilize a visual numeric recognition algorithm (optical character recognition)  96  or other type of optical processor  104  to display the proper metering data. 
     Turning now to  FIGS. 11A-B , in  FIG. 11A , the position of the sensor relative to the dials will be perfectly in the radius of the meter. An adjustment may be required (rotation of sensor or housing) to line up with desired meter dial. For instance, the installer may need to key the rotational alignment  108 . Once the adjustment is made the alignment can be made to perfectly line up  110  as is illustrated in  FIG. 11A . In  FIG. 11B  a dial  114  is shown with a center knob  112 . Using an image of the face of the dial  112  the CPU lines up with the dial circle. In less than 4000 tries, usually closer to 500 tries, the CPU subtracts until a minimum circle remains. 
       FIG. 12  illustrates how an image processing algorithm of the present invention compensates for possible alignment error in the meter reading. Using the alignment error probability, the recognition algorithm becomes tolerant to the error source  116 . 
       FIG. 13  shows the preferable depth of field for a meter reader in the present invention. In this embodiment, the infrared signal is sent by an infrared transmitter  120  through dusty glass and is measured using two receivers  118  and  122  and a lens  124 . The measurement is taken over a change  128  of 10 to 50 sec in the dial hand plane  126 . The depth of field  130  is an example of the preferable depth for the measurements in this embodiment. 
     Once the measurement is accomplished, the signal is processed using a hardware based light/dark differentiator circuit  132  shown in  FIG. 14A . Accordingly, once the signal is processed, determining when the hand goes by  134  can be determined from a hump in the A/D sampled signal. 
       FIG. 14B  illustrates a housing  136  that houses the electro-optics used in the measurement process. The focal plane is determined from a lens  124  used to focus the measured beam. In addition the housing  136  includes a circuit board. 
       FIG. 15A  shows an example of the housing  136  from the front. On the housing  136  are infrared sensors  138  similar to the receivers  118  and  122  shown in  FIG. 13 , one to ten sensors  138  may be used in this configuration.  FIG. 15B  is a wider view of the housing  136  that also includes the lens  124  and the meter arm. When glass imperfections or obstructions between the housing  136  and the meter cause bad readings, an adaptive filter can be used to provide corrections in the data. In  FIG. 15C  ten sensors  142  are shown. Using these ten sensors  142  as well as known direction and max speed  140  each LED sensor  142  is put through correlation and produces outputs like  138 . The algorithm can then pick the best match, however all ten sensors contribute to the correlation. This process makes the data received from the sensors adaptive. 
     Additionally, Kalman filtering can be used in the present invention. Kalman filtering is use of “expert” information to eliminate illegal outputs—thus improving accuracy—i.e. the expert system knows the dials go forward, that they can&#39;t go at a rate faster than 200 amps per hour on a residential electric meter. Using Kalman filtering the movement of the meter can be predicted. In  FIG. 16  the signals from  10  sensors  146  are shown at different points in time and different positions of the meter dial  148 . The actual position of the meter hand can be predicted using a Kalman filter. 
     Further  FIG. 17  illustrates that the predictable movement of the meter dial calculated using the Kalman filter can advantageously be monitored by a sensor. The error  152  can be accounted for in this system and the multiple sensitive areas of the CCD response  154  can be taken into account. The worst case scenario is that the system will hold too long on a digit, skip the next digit, but have the correct reading. 
       FIG. 18  illustrates the sensor mechanism which tracks the number of times a dial hand crosses a certain point on the dial face  160 . The acoustic  156  and the signature  158  are both seen in the signal shown in  FIG. 18 . 
       FIG. 19  shows an example of techniques used to overcome alignment problems. In the example shown in  FIG. 19 , the accuracy of the sensors  162  is good but the alignment  164  is poor. However the sensor position  166  can be used to overcome alignment accuracy problems. Two LED sensors are lined up in the rotation axis of error. In this example, receivers A and B  168  are used. The outputs for sensor A  172  and for sensor B  174  are compared in order to dynamically compensate for water, temperature, aging, ambient light and other similar potential problems occurring in the measurement. Using the differential amplifier  176 , the change in the signal is accounted for by the system. When a hump  178  is detected in the differential signal  180  the optical systems do not have to be used for a certain amount of time depending on the speed of the wheel. This process greatly enhances the battery life of the device. 
     Additionally in  FIG. 19  there is shown the example when hands appear to the sensors to touch  170 , this phenomenon may fool the optics. Accordingly, four LEDS can be used to achieve quadriture detection capability. Further this system can also detect reverse rotation such as in the case of energy theft. 
       FIG. 20  shows another example of the system of the present invention used to determine when the meter hand passes a certain point.  FIG. 20  shows an optical sensor  182  with a sensitive area  184 . Each of the optical sensors  186  and  188  are positioned similarly. In this embodiment the IR sensors  186  and  188  corresponding to signals “A”  190  and “B”  192  respectfully have a built-in lens. When the hand measurement is misaligned the difference signal  193  can be used to determine the correct measurement. It should also be noted that the measuring device is tamper proof and unaffected by changes in the ambient light. In order to achieve these features the sensors may have adaptive shutter speed to prevent overload of the sensors CCD dynamic range. In addition, even if one revolution measurement is missed the sensing algorithm can adapt to this mis-measurement 
     This invention may be conveniently implemented using a conventional general purpose digital computer or microprocessor programmed according to the teachings of the present specification, as will be apparent to those skilled in the computer art. Appropriate software coding can readily be prepared by skilled programmers based on the teachings of the present disclosure, as will be apparent to those skilled in the software art. The invention may also be implemented by the preparation of application specific integrated circuits or by interconnecting an appropriate network of conventional component circuits, as will be readily apparent to those skilled in the art. 
     The present invention includes a computer program product which is a storage medium including instructions which can be used to program a computer to perform a process of the invention. The storage medium can include, but is not limited to, an type of disk including floppy disks, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, or any type of pure software inventions (e.g., word processing, accounting, Internet related, etc.) media suitable for storing electronic instructions. 
     Additionally, this invention may be applied to temperature, pressure, flow rate, and other industrial processes. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.