Abstract:
A magnetically coupled communications port includes a switch for providing an enable signal upon coupling of a detachable magnetic coupler assembly to a fixed coupler assembly. The switch is magnetically activated and is positioned on the fixed coupler assembly in proximity to one end of a cylindrical slug of a magnetically conductive material. The opposite end of the cylindrical slug is positioned co-planar with an external face portion of the fixed coupler assembly. When the detachable magnetic coupler assembly mates with the fixed coupler assembly, contacting the face portion and the co-planar surface of the cylindrical slug, magnetic flux from the detachable magnetic coupler is concentrated through the slug causing the magnetically activated switch to switch from an inactivated position to an activated position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to communication coupler devices and more particularly to such devices having magnetic and optical characteristics which allow mating magnetic couplers to be joined for the transfer of information between electronic devices. 
     The present invention is useful in those types of applications where it is desirable or necessary to electronically communicate with electronic circuitry which is inaccessably housed, such as within a sealed enclosure. To this end, and as a preferred embodiment, the invention finds particular application in utility meters of the computerized electronically programmable type. These types of meters are most frequently designed to be programmed or re-programmed at the place of installation, such as at the customer residence or a commercial business site. Ideally, these types of meters are designed for electronic readout of meter data, for example total kilowatt hour consumption, demand kilowatt consumption and the like. 
     Programming and reading of the above types of meters is normally done by a utility company meter reader or service person utilizing a portable reader/programmer device. This device is usually provided with some type of plug device for attachment to the meter to enable the reader/programmer to communicate with the electronics inside the meter cover. 
     The use of an optical coupler for programming meters of the above type is made attractive because of the economic design and manufacturing cost incentives such a coupler affords. A further attractive feature is the high reliability of optical emitter and detector devices employed in such couplers. 
     One type of optical coupler is shown and described in co-pending U.S. patent application Ser. No. 533,896, which is a continuation of Ser. No. 190,217, filed Sept. 24, 1980 now abandoned and which is assigned to the assignee of the present invention and which is incorporated by reference in the present application as if fully set forth herein. That coupler comprises a first coupler assembly which is rigidly mounted through the meter cover and a second coupler assembly which can be magnetically attached to the first coupler assembly. The coupler is constructed such that precise alignment is maintained between the first and second coupler assemblies when they are magnetically attached to each other while inhibiting the entry of ambient light from entering between the coupled portions. 
     Although the aforementioned magnetic optical coupler provides an economical and reliable means for communicating with electronic devices which are sealed within a housing or cover, a need exists for a means of signaling the enclosed electronic device that the magnetic coupler has been mated. Such a signal can be used by the enclosed electronic device to enable the optical emitter and detector devices as well as to provide an indication that communication with an external device through the mated coupler is ready to take place. The signaling means should be reliable, tamper resistant, be able to operate through a sealed partition and have no moving parts exposed outside of the partition. 
     SUMMARY OF THE INVENTION 
     The aforementioned needs are satisfied by the present invention by the provision of a magnetically activated switch assembly. The invention, in a preferred embodiment, is advantageously applied in utility meters of the electronically programmable type, which can be externally programmed by a portable reader/programmer device having a coupler which is magnetically coupled to the utility meter. 
     In applying the apparatus of the invention, a first coupler assembly is mounted through a meter cover. This first coupler assembly is preferably fabricated from a magnetically conductive material. The coupler assembly contains a face portion which is mounted external of the meter cover. An aperture extends from this face portion into the coupler assembly. At least one optical communication means is disposed in the aperture, and is oriented therein to provide a communication path for the optical communication means through the aperture in the face portion of the coupler assembly. This optical communication means is connected to electronic circuitry inside the meter cover. A magnetic flux concentrator, preferably a cylindrical slug of magnetically conductive material, is mounted in the first coupler assembly such that one end of the cylindrical slug is positioned substantially flush with the face portion. The opposite end of the cylindrical slug is positioned adjacent a magnetically activated switching means. 
     A second coupler assembly is provided for magnetic attachment to the first coupler assembly. The second coupler assembly is preferably constructed as a magnet having a magnetized surface for mating magnetic attachment to the face portion of the first coupler assembly. In a manner similar to the first coupler assembly, the second coupler assembly also contains an aperture extending from its magnetized surface into the body of the second coupler for the containment of a second optical communication means. The orientation of the second optical communication means in the aperture of the second coupler assembly provides an optical communication path through the aperture for the establishment of a communication link between the first and second optical communication means when the two coupler assemblies are magnetically coupled. A portable reader/programmer device is connected to the second optical communication means to complete communication with the meter electronic circuitry via the mated optical coupler. 
     When the first and second coupler assemblies are magnetically coupled, the cylindrical magnetically conductive slug will conduct magnetic flux from the magnetized surface of the second coupler assembly to the magnetically activated switch, thereby causing the switch to switch from its unactivated to its activated position. In the preferred embodiment, the activation of this switch enables the meter electronic circuitry to communicate with the portable reader/programmer via the optical coupler. 
     It is therefore an object of the present invention to provide an optical coupling apparatus for the transfer of electronic information which includes a device for enabling and inhibiting the transfer of information over the optical link. 
     It is another object of the present invention to provide a magnetically detachable optical coupling apparatus characterized by incorporating a magnetically activated switch to enable transfer of information through a communication link established by the coupled apparatus. 
     A further object of the invention is to provide an optical coupling apparatus which incorporates an enabling switch inaccessably housed within an enclosure but which is activatable upon the mating of the optical link. 
     Still another object of the invention is to provide a combination magnetic and optical coupler apparatus which enables the electronic communication between electronic circuitry housed within a sealed cover of a meter and a portable electronic communication device connected external of the meter housing. 
     It is yet another object of the present invention to provide a combination optical magnetic coupler apparatus including means for enabling optical detector and/or emitter devices to effect upon coupling, unidirectional or bidirectional communication with an electronically programmable meter from a reader/programmer device connected external of the meter cover having electronics inaccessably housed therein. 
     A further object of the present invention is to provide a switch means for enabling the electronic communication between an electronically programmable meter and a reader/programmer device connected external of a meter cover having electronics inaccessably housed therein, said switch means having no moving parts exposed outside of the cover. 
     Still a further object of the present invention is to provide a reliable, tamper resistant means of enabling communication between an electronically programmable meter and a reader/programmer device connected external of the meter cover having electronics inaccessably housed therein. 
     These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a functional block diagram depicting the flow of information between a reader/programmer device and an electronically programmable meter through a magnetic optical coupler incorporating a coupler sensing switch of the present invention. 
     FIG. 2 is a side view, partly in cross-section, of a second coupler assembly of the present invention. 
     FIG. 3 is an end view, partly in cross-section, showing a portion of the second coupler assembly of FIG. 2 looking into the left side thereof. 
     FIG. 4 is an end view showing a portion of the second coupler assembly of FIG. 2 looking into the right side thereof. 
     FIG. 5 depicts a terminal block having a magnetically activated switch mounted thereon. 
     FIG. 6 is a side view, partly in cross-section, showing first and second coupler assemblies magnetically coupled for operation. 
     FIG. 7 is an end view showing a face portion of the first coupler assembly. 
     FIG. 8 is an end view showing a rear portion of the first coupler assembly. 
     FIG. 9 is an electrical schematic showing the wiring of optical communication devices used in each of the first and second couplers of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, there is shown a functional block diagram illustrating the flow of information between an electronically programmable meter, generally designated 10 and a portable reader/programmer device, generally designated 12. The electronically programmable meter includes a microprocessor 14 for receiving, processing and outputting data. The meter also includes a data source selector 16 for selecting one of at least two meter communication paths. As shown in FIG. 1, these communication paths are between either a central data acquisition and transmission system (not shown), via a telephone line modem 18, or the portable reader programmer device 12 via an optical coupler generally designated 20, having a fixed coupler segment 22 sealably mounted through a meter cover or housing (not shown) preferably in accordance with the teachings of the aforementioned U.S. patent application Ser. No. 533,895. 
     When the data source selector 16 selects the telephone modem 18, outbound data from the meter 10 flows to the modem 18 by way of a transmit data (XMIT DATA) path 24. Inbound data flows from the telephone modem 18 to the data source selector 16 by way of a first inbound data path 26. In this mode of communication, the data source selector 16 transmits the inbound data from the first inbound data path 26 to the microprocessor 14 over a receive data (RCV DATA) path 28. 
     When communicating with the programmer/reader device 12, outbound data flows from the microprocessor 14 over the XMIT DATA path 24, through the data source selector 16, over an outbound data path 29 to a light emitting diode (LED) transmitter 30 which is mounted within the fixed coupler segment 22 of the magnetic optical coupler 20, as shown and described in the aforementioned U.S. patent application Ser. No. 533,895. In this mode of communication, inbound data flows from a photocell receiver 32, which is housed within the fixed coupler segment 22 of the optical coupler 20, as shown and described in the aforementioned U.S. patent application, to the data source selector 16 by way of a second inbound data path 34. The data source selector 16 transmits the data from the second inbound data path 34 to the microprocessor 14 over the RCV DATA path 28. 
     The reader/programmer device 12, is electrically connected to a detachable magnetic coupler segment 36 of the optical coupler 20. The detachable magnetic coupler segment 36 is adapted to mate with and magnetically couple to the fixed coupler segment 22 of the optical coupler 20. The detachable magnetic coupler segment 36 includes a light emitting diode (LED) transmitter 38 which receives a data signal from the reader/programmer device 12 over an outbound data path 40. The detachable magnetic coupler segment 36 also includes a photocell receiver 42 which emits data signals to the reader/programmer device 12 over the inbound data path 44. The LED transmitter 38 and the photocell receiver 42 are mounted in the detachable magnetic coupler segment 36 preferably in the manner shown and described in the aforementioned U.S. patent application Ser. No. 533,895. 
     The fixed coupler segment 22 of the optical coupler 20 also includes a magnetically operated switching means 46 which is activated upon magnetically coupling the detachable magnetic coupler segment 36 to the fixed coupler segment 22 as will be hereinafter described. The detachable magnetic coupler segment 36 also includes a device activate switch means 48 which is operated upon mating the detachable magnetic coupler segment 36 to the fixed coupler segment 22 as will be hereinafter described. 
     Upon activation, the magnetically operated switching means 46 closes and applies ground to a terminal of the data source selector 16, by way of input line 50, causing the selector 16 to switch from the telephone modem communication paths to the portable reader/programmer device communication paths. The magnetically operated switching means 46 also applies ground to an input of the microprocessor 14, over the input path 52, thereby alerting the microprocessor 14 that communication is to occur between the meter 10 and the portable reader/programmer device 12. Upon operation, the device activate switch means 48 closes thereby signalling the reader/programmer device 12, by way of lines 53, that the optical link 20 is coupled and communication with the meter 10 can begin. Such signalling would result in the application of battery power to the reader/programmer device upon closure of switch 48. 
     Referring now to FIG. 2, there is shown a cross-sectional side view of a preferred embodiment of the detachable magnetic coupler segment 36 of the optical coupler 20. As previously described in connection with FIG. 1, the detachable coupler segment 36 is magnetically attachable to the mating fixed coupler segment 22. In its broadest context, the detachable coupler segment 36 may be comprised of a unitary magnet structure. As shown in FIG. 2, the structure of the coupler segment 36 comprises a non-magnetic body 60, having a face portion 62 preferably symmetrically designed to mate with a face portion on the fixed coupler segment 22 as will be subsequently described. The detachable magnetic coupler segment 36 has an aperture 64 extending into a cavity from the face portion of the body 60 for the retention of at least one optical communication device 65 (see FIG. 6). If only unidirectional communication is desired, there would be only one optical communication device 65 located within the aperture 64 and that device would communicate with a communication device of opposite type in an aperture of the fixed coupler segment 22, which will be subsequently described. 
     If bidirectional communication is desired, two apertures such as 64&#39; and 64&#34;, as shown in FIG. 4, are formed in the body 60 to hold optical communication devices of opposite types, such as a light emitting diode (LED) and a phototransistor (not shown). These devices are mounted within the body 60 as shown and described in the aforementioned co-pending U.S. patent application Ser. No. 533,895, which application has been incorporated by reference in this application. 
     Again referring to FIG. 2, a magnet 66 is disposed around a front annular shoulder portion 68 of the body 60. As shown at 70 in FIG. 2, the magnet 66 is preferably held in place by a suitable cement, such as epoxy to rigidly attach the magnet 66 to the entire structure or body 60. 
     A cover 72, forming a part of the body 60 and magnet assembly 66, is attached to the body 60 by any suitable means such as counter sunk screws (not shown). The cover 72 is preferably conductively magnetic material and serves essentially four purposes. The first of these purposes is to provide a partial protective cover for the coupler assembly 36. The second purpose is to provide a light shield, as shown at 74, in the form of a lip extending out over the face portion end of the magnet and the body assembly 66 and 60 respectively. Thirdly, the cover 72 provides a second alignment means 76 formed as a flat in the face portion end of the lip of the light shield 74. The alignment means 76 is symmetrically formed to co-act with a flat of alignment means positioned on a face portion of the fixed coupler segment 22 as will be subsequently described. And fourthly, the cover 72 serves as a return path of the magnetic flux, to thus improve the magnet holding force and increase the magnet retentivity. 
     The magnetic holding force is further enhanced by a conductive magnetic washer or spacer 92 disposed between the near face of the magnet 66 and cover 72. The washer 92 provides a path for magnetic flux between cover 72 and the magnet 66. 
     A slot 77 (see FIG. 4) is formed in the face portion end of the lip of the light shield 74. The slot exposes a part of a face portion 98 of the magnet 66 thereby permitting an end of an iron slug positioned in the fixed coupler segment 22 to make intimate contact with the face portion 98 of the magnet 66 when the detachable magnetic coupler segment 36 is coupled to the fixed segment 22. This intimate contact enhances magnetic flux coupling through the slug for operating a magnetic reed switch as will be subsequently described. 
     To complete the detachable coupler segment 36 of FIG. 2, a second or rear cylindrical cover 78 is attached to body 60 by three screws 80 (see FIG. 3) threaded into the body 60. As can be seen in FIG. 2, the purpose of the cover 78 is to protect the wiring extending from components mounted inside the coupler 36. One of these components is the device activate switch means 48 comprising a switch 82 which is mounted on a mounting plate 84 which in turn is attached to and spaced from body 60 using attachment screws 86 and spacers 87. As shown more clearly in FIG. 3, the mounting plate 84 is preferably T-shaped with the switch 82 mounted near the end of the leg member of the T and the mounting screws 86 being inserted through the mounting plate 84 near the ends of the cross member. The switch 82 is preferably a momentary contact form A type, and is internally spring loaded in the out direction which is off. 
     A plunger 88 extends through an aperture 90 in the body 60. The plunger 88 also extends through an aperture in washer 92 which is disposed between the magnet 66 and a shoulder on the body 60. Also extending through the aperture in the washer 92 and surrounding a portion of the plunger 88 is a bearing tube 94. The portion of the plunger 88 which is surrounded by the bearing tube 94 has a smaller diameter than the portion of the plunger 88 which is disposed through the aperture 90 in the body 60. These differences in diameters form a shoulder in the plunger which is urged against the washer 92 by the spring loaded switch pin 95. When the shoulder of the plunger 88 is urged against the washer 92, a portion 96 of the plunger 88 extends beyond the face portion 98 of the magnet 66. As will subsequently be described, when the face portion 98 of the magnet 66 engages a mating surface on the fixed coupler 20 (as shown in FIG. 5), the extending portion 96 of the plunger 90 will be depressed into the bearing tube 94, which in turn depresses the switch pin 95 causing the switch 82 to activate. As previously described the activation of the switch 82 signals the reader/programmer device 12 that the fixed coupler 22 and detachable magnetic coupler segments 36 of the optical coupler 20 have been mated and communication between the reader/programmer device 12 and the programmable meter 10 is enabled. 
     Referring now to FIG. 6, there is shown, in partial cross-section, a preferred embodiment of the optical link 20 of the present invention comprising the detachable magnetic coupler segment 36 in mating engagement with the fixed coupler segment 22. The fixed coupler segment 22 extends through and is attached to a cover 100 of the electronically programmable meter 10. In its broadest context, the fixed coupler segment 22 may be formed as an integral housing, or body generally shown as 102. The structure of the housing 102 is characterized by a body 104 having a face portion 106 and further having at least one aperture 108 extending from the face portion 106 into the body 104. 
     As shown in FIG. 6, the aperture 108 contains at least one optical communication means or device 110 mounted within aperture 108 and held in place by circuit boards 112 and 114. The boards 112 and 114 are displaced by two spacers generally shown as 116. The leads of the optical device 110 are bought through suitable holes in the circuit board 114 and are soldered to connecting terminals 118. Three conductors 120 of a cable 122 are also soldered to the terminal connectors 118. The entire assembly, comprising the optical device 110 and the circuit boards 112 and 114, is secured in place within a cavity 124 of the body 104 by two retaining screws 126 as shown in FIGS. 6 and 8. These screws 126 are passed through the spacers 116 and screwed into the body 104 through threads (not shown) in the body 104. 
     In the preferred embodiment where information is to be bidirectionally transferred, two apertures 108&#39; and 108&#34; are formed in the body 104 (see FIG. 7). Mounted within these two apertures are associated optical communication devices 110&#39; and 110&#34; shown in FIG. 9 as an emitter, such as a light emitting diode 110&#39;, and a collector, such as a photocell 110&#34;. FIG. 9 schematically shows the wiring of wires 120 of cable 122 for connecting these optical communication devices to the circuit board 114 at terminals 118. 
     The entire fixed coupler segment 22 is rigidly attached to the meter cover 100 by a nut 128 screwed onto the body 104 from the inside of the meter cover 100. To protect the inside of the meter from outside elements (such as moisture and dirt), a gasket 130 is placed on the outside of the meter cover 100 between the cover 100 and a flat washer 132. A component mounting block 134 having a thick portion 136, a thin portion 138 and an aperture 140 (see also FIG. 5) is disposed between the meter cover 100 and the nut 128 with the threaded portion 129 of the body 104 extending through the aperture 140. A flat washer 142 is placed between the nut 128 and the component mounting block 134 to prevent damage to the mounting block 134 as the nut 128 is tightened against it. In a preferred embodiment, the body 104 has an alignment pin 144 (see FIGS. 7 and 8) in the backside of an annular shoulder 146 which aligns with a mating hole in the meter cover 100 to prevent the fixed coupler segment 22 from turning and insure that the coupler 22 is properly oriented when installed. 
     Still referring to FIG. 6, a portion of the body 104 includes a face cover 148, fabricated from a soft iron, magnetically conductive material. As shown in FIGS. 6 and 8, this cover 148 is attached to the body 104 by three screws 150 threaded from the backside of the shoulder 146 into the backside of the cover 148. To complete the sealing arrangement of the fixed coupler segment 22, a gasket 152 is interposed between the shoulder 146 and the cover 148. 
     A light path is provided through the cover 148, which has an opening or aperture in the face portion to allow light communication through the front of the cover with the optical device 110. For protection of the optical device 110 a transparent cover 154 is disposed within the cover 148. The transparent cover 154 is preferably fabricated from a high impact plastic or glass substance impervious to breakage. The sealing arrangement of the fixed coupler segment 22 is further enhanced by means of another gasket 156 disposed between the transparent cover 154 and a shoulder on the inside of the cover 148. 
     As best seen in FIG. 7, the body 104, and the cover 148 forming a part thereof, also includes a first alignment means 158 shown as a flat on the bottom side of the cover 148. This alignment means 158 is configured to symmetrically align with the corresponding alignment means 76 on the cover 72 of the detachable magnetic coupler segment 36. 
     Referring to FIGS. 5 and 6, there is shown the magnetically operated switching means 46, which comprises a magnetically activated reed switch 160 electrically connected between a first 162 and second 164 terminal posts disposed on the thin portion 138 of the component mounting board 134. A pair of conductors 166 of the cable 122 are electrically connected to the terminals 162 and 164. 
     A cylindrically shaped soft iron slug 168 having a threaded end portion 170 extends through a threaded aperture in the body 104. The slug 168 is threaded through the body 104 to a position at which the end of the slug 168 extending from the body 104 makes contact with the face portion 98 of the magnet 66 of the detachable magnetic coupler segment 36 through the slot 77 when the detachable coupler segment 36 has been magnetically coupled to the fixed coupler segment 22 as shown in FIG. 6. The magnetic reed switch 160 is mounted on the thin portion 138 of the mounting block 134 in a position such that when the block 134 is assembled to the body 104, the magnetic reed switch 160 is positioned in close proximity to the other end of the iron slug 168 as shown in FIG. 6. 
     The purpose of the aforementioned adjustment of the iron slug 168 and the positioning of the magnetic reed switch 160 with respect to the iron slug 168 is as follows. When the detachable magnetic coupler segment 36 is magnetically coupled to the fixed coupler segment 22 as shown in FIG. 6, the soft iron slug 168 will conduct magnetic flux from the magnet 66 of coupler segment 36 to the reed switch 160, causing the reed switch to activate. The flux coupling from the magnet 66 to the reed switch 160 is enhanced because one end of the iron slug 168 makes contact with face portion 98 of the magnet 66 through the slot 77 in the face portion end of the lip of the light shield 74 of the cover 72 as previously described. The reed switch 160, which in the preferred embodiment is normally open, is therefore closed by this magnetic flux and held closed as long as the detachable coupler segment 36 is attached to the fixed coupler segment 22. When the detachable coupler segment 36 is detached from the fixed coupler segment 11, the reed switch 160 will open because of the absence of magnetic flux. 
     This magnetic switch will operate satisfactorily through a steel cover 100 as well as covers made of nonmetallic material. However, when used with a steel cover, a reasonable clearance aperture must be provided between the iron slug 168 and the cover 100. Such an aperture is shown in FIG. 6 and designated by the reference numeral 172. 
     The detachable magnetic coupler segment 36 is electrically connected to the reader/programmer device 12 by means of a cable 174 as shown in FIG. 6. The cable 174 contains the wires 176 which are electrically connected to the terminals of the switch 82 as well as the wires 178 which are electrically connected to the optical communication devices 65 by way of the terminals 180 mounted on printed circuit board 182. To prevent fraying of the wiring on cable 174, a rubber protective grommet 184 is preferably installed between the body 60 and the cover 78. 
     The advantages of the present invention are believed to best be realized by the utilization of a pulse code or binary communication protocol between the portable reader/programmer device 12 and the electronically programmable meter 10. When using such a protocol, the emitter devices (such as diodes 65&#39; and 110&#39;) are pulsed by electronic signals from their respective connected electronics to transmit light pulses across the communication link to their corresponding collector devices (such as phototransistors 65&#34; and 110&#34;) which in turn convert those light pulses to electronic pulses for reception by the electronic circuitry to which the collector devices are connected. 
     This type of communication protocol is particularly advantageous when used with a meter, which is shown in block diagram form as 10 in FIG. 1, which implements a programmable microprocessor 14 which must be interrogated and programmed by an external device such as the portable reader/programmer device 12. In such a meter, it is important that the microprocessor 14 know whether it is communicating with the modem 18 or the reader/programmer device 12. In addition, in order to prevent spurious light from being interpreted as programming information prior to mating of the coupler segments 22 and 36 as well as to protect and extend the life of the operational communication devices 110 contained within the fixed coupler segment 36, it is necessary that the optical communication devices remain unenergized until mating of the segments has occurred. These functions are provided by the magnetically operated switch segment 46 which is activated by the magnet 66 of the detachable coupler segment 36 through the soft iron slug 168 of the fixed coupler segment 22 upon mating of the detachable coupler segment 36 to the fixed coupler segment 22 as previously described. 
     In addition, it is important that the reader/programmer device 12 knows that the communication link required for communication with the electronically programmable meter 10 has been properly implemented. This &#34;knowledge&#34; is imparted to the reader/programmer device 12 by means of the device activate switch means 48 which closes upon mating of the detachable coupler segment 36 to the fixed coupler segment 22 as previously described. 
     From the foregoing description of the invention, it will be apparent that further modifications and alternative embodiments of it may be made without departing from its teachings; accordingly, it is our intention to encompass within the following claims the true spirit and scope of the invention.