Abstract:
A marking paint applicator for a portable electronic locator that locates buried cables and pipes via electromagnetic emissions is disclosed. The marking paint application may include an elongated support structure and a manually moveable trigger mechanism mounted adjacent an upper end of the support structure, along with a bracket assembly, a trigger mechanism, a receptacle for holding paint, and an actuating mechanism for selectively controlling release of the paint in response to operator actuation of the trigger mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND PATENTS 
     This application is a continuation of and claims priority to co-pending U.S. Utility patent application Ser. No. 12/827,993, entitled MARKING PAINT APPLICATOR FOR PORTABLE LOCATOR, filed on Jun. 30, 2010, which is a continuation of and claims priority to U.S. Utility patent application Ser. No. 11/782,572, entitled MARKING PAINT APPLICATOR FOR PORTABLE LOCATOR, filed Jul. 24, 2007, which claims priority to U.S. Provisional Patent Application Ser. No. 60/822,621, entitled MARKING PAINT APPLICATOR FOR PORTABLE LOCATOR, filed on Aug. 16, 2006. The content of each of these applications is incorporated by reference herein in its entirety for all purposes. 
    
    
     FIELD 
     This disclosure relates generally to electronic systems and methods for locating buried or otherwise inaccessible pipes and other conduits, cables, conductors and inserted transmitters, and more specifically to devices used with locating instruments to facilitate marking locations of interest on the ground surface where such buried objects are detected. 
     BACKGROUND 
     There are many situations where is it desirable to locate buried utilities such as pipes and cables. For example, prior to starting any new construction that involves excavation, it is important to locate existing underground utilities such as underground power lines, gas lines, phone lines, fiber optic cable conduits, CATV cables, sprinkler control wiring, water pipes, sewer pipes, etc. If a back hoe or other excavation equipment hits a high voltage line or a gas line, serious injury and property damage can result. Severing water mains and sewer lines leads to messy cleanups. The destruction of power and data cables can seriously disrupt the comfort and convenience of residents and cost businesses huge financial losses. 
     Buried objects can be located by sensing an electromagnetic signal emitted by the same. Some cables such as power lines are already energized and emit their own long cylindrical electromagnetic field. Location of other conductive lines necessitates their energizing with an outside electrical source having a frequency typically in a range of approximately 50 Hz to 500 kHz. Location of buried long conductors is often referred to as “line tracing.” 
     In the typical locating operation, an operator will use a portable electronic locator to determine the underground location of a buried utility, sonde, or like object, and will then use an aerosol paint can to mark on the surface of the ground the apparent location of the buried object that has been located. In this way, the location of existing underground utilities can be known to an excavator and can be avoided during excavation, preventing expensive damage and potential personal injury. However, existing locators heretofore have not made it convenient to both locate a buried utility and mark its location on the ground. The conventional approach interrupts the locate process as a result of the necessity of picking up an aerosol paint can and applying paint on the ground to mark a location of a buried pipe or conductor that has been located. This adds time to the locate process, reducing productivity. It also imposes the necessity of stooping or bending in order to apply markings. This interruption also causes the operator to take his or her attention away from the instrument being used to detect the buried utility, thus introducing the risk of an inaccurate marking. 
     Separately held tools have been developed for holding aerosol paint can and operating it from a standing position. See for example U.S. Pat. No. 5,368,202 of Smrt. Such stand alone marking paint applicators must be carried and handled separately from the locator. One prior art locator has been designed with a marking paint applicator embedded permanently into its structure. See U.S. Pat. No. 6,723,375 of Zeck et al. 
     SUMMARY 
     In accordance with one aspect, a marking paint applicator for a portable locator includes an elongated support structure and a manually moveable trigger mechanism mounted adjacent an upper end of the support structure. At least one bracket assembly is provided for removably connecting the support structure to an antenna mast of the portable locator so that the trigger mechanism will be adjacent a handle of the locator and the trigger mechanism can be squeezed by a finger of an operator&#39;s hand while grasping the handle. A receptacle is mounted to the support structure for carrying an inverted aerosol paint can and positioning a valve stem of the aerosol paint can for spraying paint onto the ground. An actuating mechanism is capable of selectively deflecting the valve stem to cause the aerosol paint can to spray paint onto the ground. A linkage connects the trigger mechanism to the actuating mechanism for deflecting the valve stem when the trigger mechanism is squeezed. 
     Various additional aspects, features, and functions are described subsequently with respect to the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the general operation of an embodiment of a marking paint applicator in accordance with the present invention that is removably attached to a portable locator. 
         FIG. 2  is an enlarged fragmentary side elevation view of the paint applicator of  FIG. 1  illustrating its receptacle loaded with an aerosol paint can and its operator-actuated trigger mechanism. 
         FIG. 3  is a view similar to  FIG. 2 , slightly rotated about a vertical axis, illustrating the detachment of the optional pair of wheels from the paint applicator of  FIG. 1 . 
         FIG. 4A  is an enlarged fragmentary portion of  FIG. 1  illustrating the operation of the trigger mechanism of the paint applicator of  FIG. 1 . 
         FIG. 4B  illustrates an icon displayed by the locator when the trigger mechanism of the paint applicator of  FIG. 1  has been squeezed by an operator. 
         FIG. 5  is a fragmentary vertical sectional view of the paint applicator of  FIG. 1  illustrating details of its linkage and valve stem actuating mechanism. 
         FIG. 6A  is an enlarged portion of  FIG. 5  illustrating further details of the valve stem actuating mechanism in its OFF state. 
         FIG. 6B  is a view similar to  FIG. 6A  illustrating the valve stem actuating mechanism in its ON state. 
         FIG. 7  is a flow diagram illustrating the process by which actuation of the trigger mechanism of the paint applicator of  FIG. 1  will cause the locator to log a paint marking. 
         FIG. 8  is a block diagram illustrating the manner in which an embedded magnet of the paint applicator of  FIG. 1  actuates a sensor in the locator, producing signals which are time-tagged and stored in a local data storage and indicated on the locator&#39;s LCD display. 
         FIG. 9A  illustrates an alternate embodiment of the present invention that utilizes a matrix-array of emission orifices fed from a single reservoir. 
         FIG. 9B  is a block diagram of a control system for the emission orifices of  FIG. 9A . 
         FIG. 10A  illustrates an alternate embodiment of the present invention which utilizes a stencil beneath the nozzle of the spray can to form recognizable patterns (characters, numbers, etc.) on the pavement. 
         FIG. 10B  is a plan view of a representative stencil used in the alternate embodiment of  FIG. 10A . 
     
    
    
     DETAILED DESCRIPTION 
     The marking paint applicator of the present invention is an accessory which enables an operator of a portable electronic locator used to locate buried utilities to place paint marks on the ground to indicate their determined locations. The marking paint applicator of the present invention is readily attachable to the portable locator and provides a convenient means for simultaneously placing paint marks in the exact location indicated by the locator&#39;s display. The accessory requires no change of position or attention-focus on the part of the operator. The operator need not bend down with a spray can, or carry a stand alone paint applicator. 
     Referring to  FIG. 1 , a marking paint applicator  10  in accordance with an embodiment of the present invention includes a support structure  12  in the form of a tube. The support structure  12  is removably attached to the antenna mast  14  of a portable locator  16  with bracket assemblies in the form of two semi-flexible clips  18  and  20 . The use of an elongate tube as the support structure  12  is advantageous in that it can be made of strong, lightweight material, such as plastic or composite material, with a diameter and length comparable to that of the antenna mast  14 . However the support structure  12  could be widely varied to comprise any type of frame or combined frame elements for accomplishing the purposes hereafter described. The clips  18  and  20  may be spring-loaded alligator-style clips that firmly clasp the antenna mast  14 . Alternative means for releasably attaching the support structure  12  to the exterior of the antenna mast  14  include brackets that can be held together with bolts and nuts, zip-ties, brackets held to the antenna mast with screws, snap-fit components, joiner pieces, etc. 
     The paint applicator  10  can be advantageously used as an accessory with a portable locator of the type disclosed in U.S. Pat. No. 7,009,399 of Mark S. Olsson et al. granted Mar. 7, 2006, the entire disclosure of which is hereby incorporated by reference. That patent discloses a portable electronic locator similar to the portable locator  16  illustrated in  FIG. 1 . Both have a housing  22 , a display  24  ( FIGS. 4B and 8 ) located on the housing  22  and an elongate antenna mast  14  ( FIG. 1 ) extending from the housing  22  and supporting a plurality of antennas  26 ,  28  and  30 . Both have a horizontally extending handle (not visible in  FIG. 1 ) integrally formed as a part of the housing  22 . Both have a circuit (not illustrated) that is at least is partially located in the housing  22  for receiving signals from the antennas  26 ,  28  and  30  induced therein by electromagnetic signals emitted by a buried utility. This circuit is capable of determining a location of the buried utility and indicating a location of the buried utility on the display  24 . 
     Referring still to  FIG. 1 , a trigger mechanism  32  of the marking paint applicator  10  can be actuated by the index finger of an operator  34  during the locate operation. The support structure  12  is attached to a receptacle  36  for holding an aerosol paint can  38  which can be selectively activated to spray marking paint of any desired color downward by squeezing the trigger mechanism  32  upwardly with the index finger. The aerosol paint can  38  is of a commercially available type widely manufactured for the purpose of making marks on the ground. The aerosol paint can  38  dispenses a stream of brightly colored paint generally along the vertical axis of the cylinder of the can, as opposed to generally orthogonal thereto. The support structure  12 , clips  18  and  20 , and receptacle  36  are preferably made of non-magnetic material such as plastic in order to minimize signal distortion in the normal process of locating with the locator  16 . The receptacle  36  is preferably made up of split semi-cylindrical holder that due to its shape, dimensions and resilient plastic construction that can be spread apart to insert the aerosol paint can  38  in an inverted position. Thereafter the receptacle  36  will squeeze the aerosol paint can  38  to firmly hold it in place. The receptacle  36  has a lip or projections (not illustrated) that extend radially inwardly and engage the end of the aerosol paint can  38  to establish its lowermost position and prevent it from falling out of the receptacle  36 . 
     The receptacle  36  is mounted to the support structure  12  at a predetermined height that places a valve stem  40  ( FIG. 5 ) of the aerosol paint can  38  near the lower end of the locator  16  so that paint sprayed from the aerosol paint can  38  will only need to be ejected a short distance before reaching the ground. This insures a bright, well demarcated line of paint and little chance of wet paint ending up on the antenna mast  14  or antennas  26 ,  28  or  30 . It is not necessary for the valve stem  40  of the aerosol paint can  38  to extend below the lowermost antenna  26  or below the lower end of the support structure  12 . Indeed it may be desirable for the valve stem  40  to be a few inches above the lower end of the locator  16 . 
     Referring to  FIG. 2 , an attachment mount  42  attaches the receptacle  36  to the support structure  12 . The support structure  12  is removably equipped with a pair of wheels  44  at the lower end thereof to enable smooth and steady transport of the locator  16  along the ground and straight-line painting in the desired area as illustrated in  FIG. 1 . Wheels  44  can be detached as illustrated in  FIG. 3  by removing locking pins, bolt assemblies or other means of attachment (not illustrated). 
     Referring to  FIG. 4A , the trigger mechanism  32  may be a rigid loop of injection molded plastic with a shape suitable for pulling with an operator&#39;s index finger. As best seen in  FIG. 1 , the operator wraps his or her thumb around the horizontal handle of the locator  16 . The handle connects a rearward portion  22   a  of the housing  22  with a forward portion  22   b  of the housing  22 . The support structure  12  and clips  18  and  20  ( FIG. 1 ) are dimensioned and configured to place the trigger mechanism  32  at the appropriate location relative to the handle of the locator  16  for the best ergonomic utilization of the trigger mechanism  32  by the hand of an operator that is simultaneously being used to grasp the handle to carry the locator  16 . 
     Referring still to  FIG. 4A , a position indicating element in the form of a permanent magnet  46  is embedded in the trigger mechanism  32  and moves vertically adjacent the exterior of the lower forward portion  22   b  of the locator housing  22  when activation occurs. A sensor such as a reed switch  48  ( FIG. 8 ) is mounted within the locator housing portion  22   b  and detects the movement of the permanent magnet  46 . When the trigger mechanism  32  is manually pulled upwardly, the permanent magnet  46  moves into registration or alignment with the reed switch  48 . This causes the contacts of the reed switch  48  to close, in turn causing the display  24  ( FIG. 4B ) of the locator  16  to indicate a paint icon  50  ( FIG. 4B ) that tells the operator  34  that a paint marking has just been made. Other forms of sensors can be used besides the reed switch  48 , such as a Hall effect sensor. The marking paint applicator  10  can also transmit a signal optically or wirelessly to the locator  16  to indicate that the trigger mechanism  32  has been activated and paint has been sprayed on the ground. 
     Referring to  FIG. 5 , a linkage including a rod  52  and a coupling  54  are connected to the trigger mechanism  32  such that they move upwardly when the trigger mechanism  32  is squeezed. The rod  52  extends centrally within the support structure  12 . A bushing  56  centers the rod  52  at the upper end of the support structure  12 . Referring to  FIG. 6A , the rod  52  is loaded with a coil spring  58  which returns it to its lowermost starting position when the trigger mechanism  32  is released. The coil spring  58  is compressed between a fixed divider wall  60  and a movable divider wall  62 . The rod  52  extends through holes in the centers of the divider walls  60  and  62 . A valve stem actuating mechanism includes an angle-block  68  that is connected to the lower end of the rod  52 . The valve stem actuating mechanism translates the vertical motion of the rod  52  into lateral motion. The valve stem actuating mechanism further includes a tongue  70  that is situated so as to be moved outward by the raising of the angle-block  68 . As illustrated in  FIG. 6B , upward vertical movement of the spring-loaded rod  52  lifts the angle-block  68 . This moves the tongue  70  laterally, and its distal end presses against the valve stem  40  of the aerosol paint can  38  visible in  FIG. 5 . As illustrated in  FIG. 6B , this causes the valve stem  40  to deflect laterally and open. A stream of paint is then directed downwardly onto the ground at a location beneath the end of the locator- 16 . When the trigger mechanism  32  is released, the spring  58  biases the trigger mechanism  32  to an OFF (no spray) state in which the valve stem actuator mechanism is not deflecting the valve stem  40 . 
       FIG. 7  is a flow diagram illustrating the process by which actuation of the trigger mechanism  32  of the paint applicator  10  of  FIG. 1  will cause the locator  16  to tag the marking event. In step  100  the permanent magnet  46  is moved by the trigger mechanism  32 . In step  102  this movement is detected by the reed switch  48  which transmits a signal to the locator&#39;s micro-processor or micro-controller MCU  72  ( FIG. 8 ). In step  104  a paint-event time stamp is added by the locator  16  to tag the event. In step  106  the data is stored with its time-tag in data storage onboard the locator  16  and may be used in computing mapping information, downloaded for use in other devices, or the like. 
       FIG. 8  is a block diagram illustrating the manner in which the embedded permanent magnet  46  closes the reed switch  48  mounted in the locator  16 , producing signals which are time-tagged and stored in a local data storage and indicated on the locator&#39;s LCD display  24 . The reed switch  48  is connected to the MCU  72  of the locator  16 , possibly through an interface (not illustrated). The MCU  72  in turn is connected to the LCD display  24 , possibly through a driver (not illustrated). The MCU  72  preferably has a bi-directional connection with an on-board memory or local data store  74  for logging the paint marking event 
     Referring now to  FIG. 9A , an alternate embodiment of the present invention employs an array of electronically controllable emission orifices  902  drawing from a paint reservoir  904  which is pressurized. The emission orifices  902  open and close based on control signals received on a control channel  914 . In this way, individual characters, numbers, or other forms can be created to add information to the painted mark caused by the operator. 
     Referring to  FIG. 9B  a user interface  906  is connected to a character register  908  in the form of a memory that stores character or other byte strings. The character register  908  is in turn connected to a print head control driver  910  that translates user input into control signals and communicates these control signals to an emitter array  912 . The control signals cause individual emission orifices  902  ( FIG. 9A ) to open and close in a timed sequence calculated to produce the desired patterns in the painted markings, in a fashion similar to the manner in which an ink jet print head prints graphics and alphanumeric indicia on paper. 
     Referring to  FIG. 10A , in another alternate embodiment a formed collar  1006  contains a slot  1008  and tabs  1002  or similar means to retain a stencil  1004  cut to portray a desired pattern in the spray marking. The stencil  1004  is held by the collar  1006  directly under the spray-can valve stem  40  ( FIG. 6B ). The form of the cutouts on the stencil  1004  governs the pattern made by the paint reaching the ground. The user simply selects the desired stencil  1004  and fixes it in place in the collar  1006  before marking. 
       FIG. 10B  illustrates an example of the stencil  1004 . It may be formed from a semi-rigid plastic sheet. The sheet material is die cut into a circular shape, with cutouts representing letters or other indicia, and peripheral notches  1010 . The stencil  1004  may be slid into collar  1006  ( FIG. 10A ) and locked in place by tabs  1002  formed on the collar  1006 . The stencil  1004  enables the operator to mark his locates, in this example, with a utility company identifier. In the example illustrated in  FIG. 10B , the company identifier is the acronym PGE, which stands for Pacific Gas &amp; Electric. 
     Conventional spray can markers use the color of the paint alone to provide an indication of the type and location of the detected utility. The alternate embodiments of  FIGS. 9B and 10A  add to this limited information by providing the ability to add symbols, numbers or characters to the sprayed markings. 
     Persons skilled in the art of locating underground utilities will appreciate that we have invented a new combination of a portable electronic locator with a detachable external marking paint applicator that can optionally communicate with the locator for logging a paint marking event. The marking paint applicator is advantageously externally mounted on, and carried by, the locator. Heretofore operators had to either bend over to use a conventional aerosol paint can, carry a separate stand alone paint marking applicator, or employ a complex locator with an internally integrated aerosol paint can with a complicated electrically actuated valve stem actuator. Prior marking paint applicators used with portable locators lack the flexibility of readily attaching to, and detaching from, the locator, which is a distinct need in the industry. Moreover, locating or line tracing requires marking capabilities with ease of use and minimal distraction from the instrument and these functions are advantageously achieved with our invention. As illustrated in  FIG. 1 , the marking paint applicator  10  can be actuated by the same hand that is carrying the locator, allowing the operator  34  the freedom to use his or her other hand to hold a cell phone, clip board, beverage, etc. Other aerosol paint cans of various colors can be conveniently carried by the operator  34  in a holster (not shown) worn around the waist. Specific industry standard colors designate different types of cables and pipes such as power, communications, water, gas, sewer and so forth. These other aerosol paint cans may be swapped into and out of the receptacle  36  as needed. 
     Other embodiments of the marking paint applicator of the present will be appreciated by those skilled in the art in view of these teachings set forth above. For example, the receptacle need not be a split cylinder but could be any means for receiving and holding a conventional cylindrical aerosol paint can made for marking the location of buried utilities, such as a pair of plastic loops, arms, a shelf, zip ties, radial clamps, suction cups, tape, Velcro fasteners strips, elastic straps, etc. The support structure  12  and the receptacle  36  could be formed as one integral structure. The linkage and valve stem actuation mechanism for engaging the valve stem could be widely varied. See for example, the disclosures of U.S. Pat. No. 3,485,206 of Smrt, U.S. Pat. No. 5,368,202 of Smrt, U.S. Pat. No. 6, 294,022 of Eslambolchi et al., U.S. Pat. No. 6,723,375 of Zeck et al., U.S. Pat. No. 7,048,151 or Wertz et al., the disclosures of which are incorporated by reference herein. 
     The rod  52  could be replaced with a flat arm or a cable. An electrically activated mechanism, e.g. a motor of solenoid driven mechanism, could be used for selectively deflecting the valve stem to cause the aerosol paint can to spray paint onto the ground when the trigger mechanism is squeezed, thereby eliminating the need for any mechanical linkage operatively connecting the trigger mechanism  32  and the device the mechanism that deflects the valve stem  40 . The trigger mechanism  32  can be varied for actuation by other fingers, the thumb, or the entire hand. The trigger mechanism could be provided in the form of a push button or other type of switch operatively connected to an electrical valve stem actuating mechanism via wires or other conductors. 
     The support structure  12  need not be attached solely to the antenna mast  14  and instead could be solely attached to the locator housing  22 , or the support structure  12  could be attached to both the antenna mast  14  and the housing  22 . Where the support structure  12  is releasably attached to the housing various forms of attachment means can be utilized such as screws, bolts, brackets, Velcro strips, snaps, snap-fit components, joiner pieces, elastic straps, etc. Therefore, the protection afforded our invention should only be limited in accordance with the following claims and their equivalents.