Abstract:
A utility meter reading device includes a set of stator wheels each including a plurality of conductive segments and a set of indexable digit discs driven sequentially by consumption of a provided utility and having each a conductive segment movable upon rotation of a respective disc into capacitive alignment with one of the conductive segments of a stator wheel; a micro-controller supplies a current signal to the meter discs and stators and through a circuit reads the amount of the utility consumed as reflected in the alignment of certain ones of the conductive segments of the discs and stator wheels.

Description:
FIELD OF THE INVENTION 
     The present invention relates to utility meter reading devices that can be accessed from a remote location in order to reduce the time and labor required to accurately record data from a customer&#39;s meter. 
     BACKGROUND OF THE INVENTION 
     In the distribution of such utilities as water, gas or electricity, mechanical meters have been employed to measure consumption of the utility at or near the customer&#39;s site. To reduce the costs associated with reading such meters, efforts have been directed to modification or replacement of such meters with equipment that will allow remote access to the mechanical meter register in such a way that a determination of the amount of the utility that has been consumed can be made. While the replacement meters have proven useful, their expense has been a limitations on their implementation by utility suppliers particularly where the older mechanical meters continue to function correctly. 
     Incorporation of electronic reader devices into mechanical dial or disk meters has been attempted with some success but, again, care must be taken to avoid upsetting the register operation so as not to render the readings inaccurate. Typically, the installed mechanical type meters use a plurality of wheels such as is described in U.S. Pat. No. 3,806,904, which register units of a utility consumed in tens, hundreds, thousands, of units of the quantity used. Each wheel is divided into equal sections of ten units and the wheels are coupled where ten rotations of the tens wheels will cause one rotation of the hundreds wheel, etc. A segment scale or ladder is connected to each wheel to provide an electrical signal indicative of the position of its wheel and this readily converts to the quantity of die utility consumed. A receptacle is used to house a circuit board or wiring matrix that is accessible by reader device which records information stored in the receptacle as indicative of the position of its wheel and this readily converts to the quantity of the utility consumed. 
     Other prior art efforts are disclosed in U.S. Pat. Nos. 3,840,866 and 4,652,877. 
     SUMMARY OF THE INVENTION 
     The present invention avoids the drawbacks of the prior art by providing, in one form, a single chip micro-controller encoder that minimizes or eliminates the requirement common to the prior art of attaching cumbersome devices to the mechanical rotating disk type meter devices. Digit wheel sensing circuitry is provided that can be remotely activated to read the positions of the digit wheels of the mechanical meter so that the micro-controller can interpret the detected signals and communicate with a, meter reading device. Preferably, the micro-controller does not include a power source thus simplifying installation and maintenance. Further, the sensing is effected by inserting conductive members adjacent and attached to each digit wheel and cooperating stator discs sandwiched between each digit wheel pair. With this arrangement, alignment between a digit on the digit wheel and an associated conductive segment and a corresponding segment on the adjacent stator wheel will form a parallel plate capacitors. The second set of plates is at the center of the wheels and provides a return signal. 
     A meter reader is employed to activate the system and provide low level power to the system. The micro-controller directs an alternating current signal of 455 KHz sequentially to each of the ten stator board segments starting with the zero segment and ending with the “nine” segment. Preferably, all the segments on the digit wheel segments are connected electrically together and driven with the 455 KHz signal simultaneously. Capacitive coupling between an aligned stator segment and a digit wheel segments will result in a transmitted signal pulse for each pair of stator and digit wheels through the wheel slip-ring segment to the stator slip-ring segment to create a coupling such as a slip ring capacitor to the micro-controller. The difference in amplitude or other characteristic of the transmitted signal will signify to the micro-controller alignment with the known stator position and thus an accurate measure of position and thereby consumption of the utility. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is schematic, perspective view of a digit wheel and stator segment on a rotor with a slip ring capacitor; 
     FIGS. 2A and 2B are a circuit layout for the motherboard of the micro-controller; 
     FIG. 3 is circuit layout for the reader; and 
     FIG. 4 is the circuit layout for a stator segment and wheel segment 
     FIG. 5 is a schematic, perspective view of two digit wheels and a stator segment on a rotor with a slip ring capacitor; 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, in FIG. 1, there is shown a schematic illustration of segments of a stator wheel  10  and a digit wheel  14 . The digit wheels  14  are mounted for rotation with the drive shaft while the stator wheels  10  are stationary relative to the shaft  12 . It will be understood that the meter is of standard construction having a plurality of digit wheels  14  which are mechanically operated and coupled to move in specified increments as is conventional. The first one of the digit wheels will move a single unit for each unit of the utility consumed such as water or electricity while an adjacent digit wheel will move after  10  units of the first wheel and the third wheel will move in sequence after  10  movements of the second wheel and a fourth wheel will move after  10  movements of the third wheel. A fifth and sixth wheel may be provided depending on usage. 
     As is conventional in utility meters, each digit wheel  14  is typically divided into unit segments wits the segments of the wheels representing either ones, tens, hundreds or thousands of units. The wheels are sequentially coupled to measure utility consumption. According to the present invention, each digit wheel  14  will be associated with a single stator wheel  10  although a single stator wheel may be configured to service two digit wheels by sandwiching a stator wheel between two digit wheels. Each wheel is divided into segments one of which shown in FIG.  1  and each segment at its outer radial periphery is provided with a conductive area  20  for the stators and  22  for the digit wheels  14 . Each of these areas  20  and  22  are connected through a conductive line such as the one shown at  21  to the motherboard shown in FIG.  2 . Since the stator wheel remains stationary, the signal is returned from the digit wheel slip-ring segment  16  to the stator wheel slip-ring segment  18  by capacitive coupling to transfer the signal data to line  23  to the motherboard as explained below. 
     With reference to FIGS. 2A and 2B, there is schematically illustrated a circuit layout for the micro-controller  26  and the connection of a plurality of conductive areas  20  and  22 . When a meter reading is required, the micro-controller  26  directs the application of the 455 KHz alternating current signal sequentially to each of the stator board conductive areas  20  starting with the zero unit area and ending with the  9  area. The transmitted signal will couple to a conductive area  22  on the digit wheel that is at that moment aligned with the particular conductive area  20  being driven. This signal will return to the micro-controller board  26  through the slip-ring capacitor  16 ,  18  and the line  23  associated with the particular stator wheel  10 . The received signal will be amplified by amplifier  30  and the signal then passed through a band-pass filter  41  to be further amplified by amplifiers  32  and  34 . The analog signal may then be converted to a digital signal at comparator  36  before being passed to a multiplexor unit as described below. 
     Micro-controller  26  is powered to maintain an internal operating voltage of 3.0 volts by a suitable regulator integrated circuit such as is provided at  36  as is commercially available. 
     Typically, the first function of the micro-controller  26  is to identify the reader device as a three wire or two wire device as these are the most commonly used reading devices on the market. Each of these readers provides distinctive the signatures in terms of activating frequencies and the micro-controller  26  can be set to identify and distinguish between these two as well as other reader activation frequencies such as, by way of example, connecting other reading devices defined by reception of a unique sequence of the 3 Kz signal burst of 40 ms duration followed by a steady DC level signal. Such a reader will be connected at the terminals  31  in FIG. 2A in a conventional manner. The signal provided by the external reader is routed to a series of multiplexor circuits through conventional resistances, rectifiers and filters as shown. 
     The next function of the micro-controller  26  is to determine the position of the digit wheels  14 . With the micro-controller unit clocked at 455 KHz signal with a 3.0 volt amplitude, the energy is available to bridge the two parallel-plate capacitor as defined by the conductive areas  20  and  22  for each digit wheel  14  and stator wheel  10  as described above. As noted above, micro-controller  26  directly signals sequentially each of the areas of the stator wheels segments. Typically there will be at least three stator boards or wheels  10  but as many as six may be employed for a multiple number of the digit wheels  14 . This is done through digital multiplexor circuits such as provided at  40 ,  42  in the microcontroller  26 . During transmission of the 455 KHz signal, the micro-controller will sequence, multiplexer  40  to obtain a received signal amplitude value for each digit wheel in the encoder. 
     The received signal from each digit wheels slip ring  16  is very weak and has a high source impedance. A FET buffer amplifier may be provided for each digit wheel and will be located on the stator wheel or board preferably close to the stator digit wheel signal receiving slip ring segments. 
     FIG. 4 illustrates the typical circuit for these stator boards or wheels. It will be understood that a six digit wheel encoder will require three stator boards with one being sandwiched between two digit wheels while a four digit wheel encoder requires only two stator boards. 
     The received signal amplitude is inversely proportional to the size of the gap between the fixed stator conductive areas and the digit wheels conductive areas. In order to possess acceptable position sensing reliability, an air gap should be on the order of 5 mil thick and plastic gap less than 10 mil. 
     The micro-controller contains the encoding software that determines wheel position based on signal strength and uses an appropriate algorithm to avoid digit wheel rollover errors. 
     Connection of the micro controller to a two line reader device should be apparent from the foregoing. 
     A standard ASCII terminal may be employed to communicate with the encoder of FIG.  3 . The user may read a program into the encoder to accommodate variations in utility meters to be read in terms of the identification numbers and the signal amplitudes employed for reading the digit wheel positions.