Abstract:
A telescoping mast with a cabling system configured to cover and store cable within the structure of the mast and able to efficiently extend and retract multiple telescoping sections without jar and minimal energy. The telescoping mast has a hollow mast housing. A telescoping section is nested within the interior of the mast housing. A set of upper pulleys affixed to the upper end of the mast housing, while a set of lower pulleys affixed to the lower end of the telescoping section. A cable is threaded through the first upper pulleys and first lower pulleys such that a first end of the cable is attached to the mast housing and the cable remains taut when the telescoping section is raised or lowered.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 12/456,445, entitled “Telescoping Mast,” filed on Jun. 16, 2009. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     Aspects of the present invention relate in general to cable storage in a retractable telescoping mast. Aspects include a drive mechanism apparatus capable of efficiently storing cable in an extending and retracting the telescoping mast. Further aspects of the invention include an apparatus that spools cable during the extension and retraction of an antenna mast. 
     2. Description of the Related Art 
     Telescoping masts of various types have been used in broadcasting and receiving radio messages in many different environments. Included in such developments are telescoping masts, which can be extended vertically or retracted vertically so that they can be mounted on a vehicle and transported to a desired site. 
     Telescoping masts are frequently used in mobile applications where a radio frequency antenna, temporary cell phone tower, camera, microwave television broadcast antenna or other payloads need to be placed in a position quickly and efficiently. 
     A mast can be retractable—wherein the mast can be retracted into a storage position in which the mast is relatively short in its overall height dimension. When fully extended or deployed, the overall height is many times larger than its retracted storage height dimension. 
     Most telescoping masts take a long time to deploy. For example, a four section steel mast might deploy from a 30 foot nested position to a 90 foot deployed position, in about 15 minutes. The energy requirement to move such a heavy and unwieldy mast is also enormous, resulting in the use of expensive motors in a mast drive mechanism. 
     Faster deploying units require greater power requirements to move the mast, and suffer from even greater problems. Usually the mast payload contains sensitive equipment, which can be damaged if the extension or retraction of the mast is sudden, or results in a jarring movement. 
     A payload will have electrical requirements. Typically, in such an environment, masts externally route electrical cable to the payload mounted on top of the mast. 
     SUMMARY 
     A telescoping mast has a cabling system designed to cover and store cable within the structure of the mast. The telescoping mast has a hollow mast housing. A telescoping section is nested within the interior of the mast housing. A set of upper pulleys affixed to the upper end of the mast housing, while a set of lower pulleys affixed to the lower end of the telescoping section. A cable is threaded through the first upper pulleys and first lower pulleys such that a first end of the cable is attached to the mast housing and the cable remains taut when the telescoping section is raised or lowered. 
     The mast is able to efficiently extend and retract multiple telescoping sections without jar and minimal energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIGS. 1A-D  illustrates an embodiment of a telescoping mast and cabling system deployed in an extended and retracted positions. 
         FIG. 2  is a diagram of a telescoping mast drive mechanism used to efficiently extend and retract the telescoping mast. 
         FIG. 3  is a block diagram of a telescoping mast computation unit used to control the drive mechanism. 
         FIG. 4  is a flow chart of a method to control the extension and retraction of a telescoping mast without jar. 
     
    
    
     DETAILED DESCRIPTION 
     One aspect of the present invention includes the understanding that when cable is routed external to the mast, damage to unprotected cable easily occurs due to contact with objects; consequently, embodiments of the present invention route cable (electrical, optical, or any other cable known in the art) internally within the mast. Consequently, embodiments protect cable from external objects and environmental conditions by keeping the cable completely covered and stored within the structure of the mast. 
     In some embodiments, cable runs from the base of the mast to the payload mounted at the top of the mast. The cable is stored internally within the mast housing by spooling up over a set of pulleys. The pulleys move in relation to the mast height and payout or retract the proper length of cable to match the length of mast extension. 
     Another aspect of the present invention includes the realization that motors driving a telescoping mast may be supplemented by alternate power sources, and that controlling the motors with a computation unit may be used to eliminate jar in telescoping mast movement, resulting in a “soft landing” at any position. 
     Additionally, the speed of telescoping masts carrying camera payloads may have additional design considerations. For example, such masts deployed in hostile or combat areas may need to rapidly ascend and descend to avoid enemy fire. 
     Embodiments of the present invention include an apparatus, method, and computer-readable medium configured to control antenna movement to eliminate jar. Other embodiments of the present invention may include supplemental power sources to assist and reduce the power requirements of an electric motor. 
     Operation of embodiments of the present invention may be illustrated by example.  FIGS. 1A-D  depict an example telescoping mast, constructed and operative in accordance with an embodiment of the present invention. Telescoping mast  1000 , as shown in  FIG. 1A , is a mast assembly extended with telescoping sections  1200 A-G. For illustrative purposes only, seven telescoping sections  1200 A-G are depicted supporting a payload  1100 . It is understood by those known in the art that in embodiments of the present invention may be utilized with any number of telescoping sections  1200 . An example mast assembly is U.S. Pat. No. 6,046,706, entitled “Antenna Mast and Method of Using Same.” Payload  1100  may be any a radio frequency antenna, temporary cell phone tower antenna, camera, microwave television broadcast antenna or other payload known in the art. 
     In  FIGS. 1A-D , a drive mechanism  2000  is used to power and control the extension and retraction of the mast  1000 . 
     Similarly,  FIG. 1B  depicts an external view of telescoping mast  1000  in a retracted (or “nested”) state. 
     Moving on, we now discuss a cabling system of pulleys within the telescoping mast  1000 .  FIGS. 1C-D  illustrate a system of pulleys within only a single telescoping section. This example is for illustrative purposes only. It is understood by those known in the art that this concept applies equally to any number of telescoping sections. Furthermore, it is worth noting that multiple cabling systems may be run in parallel to support multiple types of cable. Embodiments may include a separate cabling systems for electrical power, digital or analog video/audio, packetized electronic data, or all of the above. 
       FIG. 1C  illustrates internal features of telescoping mast  1000  in a retracted position. As shown, cable  1300  runs from the base of the mast to the payload  1100  mounted at the top of the mast. The cable is stored internally within the mast housing by spooling up over sets of pulleys,  1400 A-B,  1500 A-B. The relative position of pulleys  1400 A-B and  1500 A-B is shown when the mast is in the nested or retracted position. Pulleys  1500 A-B are attached near the bottom of largest moving telescoping section  1200 B of the mast  1000 . The bottom of the largest moving telescoping section  1200 B is directly driven vertically by a lead screw, which is further discussed below. The pulleys move in relation to the mast height and payout or retract the proper length of cable to match the length of mast extension. The mast housing may also serve to protect the cable from external elements such as rain, dirt, tree limbs, moving objects or other external elements. Pulleys  1400 A-B are attached on the inside and near the top of outer stationary section  1200 A of the mast  1000 . The outer stationary section  1200 A of the mast  1000  may also referred to as the mast housing. 
     As depicted, cable  1300  is a multi-conductor flexible electrical cable that will move through pulleys  1400 A-B and  1500 A-B as the mast  1000  is extended and retracted. As understood by one of ordinary skill in the art, other embodiments may use electrical, optical, computer-networking, or any other cable known in the art. Connectors  1600 A-B may be attached to either end of the cable  1300 , allowing quick electrical/mechanical disconnect of the payload at the top and the control/monitor equipment at the base of the mast  1000 . 
       FIG. 1D  depicts the position of pulleys  1400 A-B and  1500 A-B when mast  1000  is extended. As can be seen, pulleys  1400 A-B and  1500 A-B are closer together, allowing the stored cable  1300  to pay out for any extended mast height. This system of pulleys  1400 A-B and  1500 A-B, along with their relative attachment points  1600 A-B, keeps the cable  1300  under constant tension whether the mast is fully extended, nested or anywhere in between. 
       FIG. 2  illustrates an embodiment of a drive mechanism  2000  controlled by a computation unit  3000 , constructed and operative in accordance with an embodiment of the present invention. Drive mechanism  2000  includes a drive shaft  2010  with multiple bearings  2020 A-B, coupled to an electric motor  2040  through gears  2050 A-B. The drive mechanism  2000  further includes a position feedback sensor  2030 , a motor  2040 , and a computation unit  3000 . In some instances, drive mechanism  2000  may include a crank  2100 , to enable manual extension or retraction of the mast  1000 . 
     The drive shaft  2010  itself may be connected to the internal portions of the telescoping sections  1200  via a lead screw attachment point  2070 . It is understood that any attachment point  2070  known in the art capable of transferring the motion of drive shaft  2010  to telescoping sections  1200  would be sufficient. 
     Position feedback sensor  2030  may any sensor known in the art configured to communicate the telescoping mast  1000  position to computation unit  3000 . The operation of computation unit  3000  is described below. 
     Motor  2040  may be any motor known in the art capable of raising or lowering telescoping mast  1000 . For illustrative purposes only, motor  2040  is assumed to be an electric motor. The capacity of electric motor  2040  is determined by the mast size. Larger masts require greater horsepower motors. For example, electric motor  2040  could be a ⅛ horsepower DC permanent magnet motor. 
     Electric motor  2040  may be further supplemented with power from electrical energy storage unit  2060  and/or spring motor  2080 . 
     Electrical energy storage unit  2060  may be any electrical energy storage unit known in the art, including, but not limited to an ultra capacitor or battery. Electrical energy storage unit  2060  provides a “power buffer” between the peak demands of mast (during mast raising and lowering) and the average load on the electric motor  2040 . Moreover, electrical energy storage unit  2060  allows telescoping mast  1000  to extend or retract if motor  2040  is inoperable or damaged. 
     Spring motor  2080  may be any potential energy storage unit known in the art. Spring motor  2080  may assist or replace motor  2040  in extending or retracting mast  1000 . Additionally spring motor  2080  is balanced and designed to match the weight and mass of the mast  1000  and its payload  1100 . 
     In some embodiments, spring motor  2080  may be a constructed from a stressed constant force spring, such as B-Motor springs. B-Motor springs provide high amounts of torque in a small package. An example of such a spring motor  2080  is a constant torque motor from Spiroflex Division of the Kern-Liebers Ltd., part of the Kern-Liebers Group of Companies, of Schramberg, Germany. These spring motors  2080  provide rotational energy from the torque output drum, or linear motion with the use of a pulley, cable, or webbing. While it is convenient for the design that the spring motor  2080  to have constant torque, other spring motors known in the art, such as torsion bars, may be equally applicable. 
     Crank  2100  may be any manual crank known in the art to enable manual extension or retraction of telescoping mast  1000 . Crank  2100  allows users to manually extend or retract telescoping mast  1000  when motor  2040  is inoperable. In some instances, energy from crank  2100  may also be stored by spring motor  2080 . 
       FIG. 3  depicts a computation unit  3000 , constructed and operative in accordance with an embodiment of the present invention. Computation unit  3000  comprises a central processing unit  3100  capable of communicating to electric motor  2040 , and position feedback sensor  2030 . Computation unit  3000  may run an embedded operating system (OS) and include at least one processor or central processing unit (CPU)  3100 . In some alternate embodiments, computation unit  3000  runs a standard non-real-time operating system. Central processing unit  3100  may be any microprocessor or micro-controller as is known in the art. 
     The software for programming the central processing unit  3100  may be found at a computer-readable storage medium (not shown) or, alternatively, from another location across a communications network. Central processing unit  3100  is connected to computer memory. Computation unit  3000  may be controlled by an operating system that is executed within computer memory. 
     Storage medium may be a conventional read/write memory such as a magnetic disk drive, floppy disk drive, compact-disk read-only-memory (CD-ROM) drive, digital versatile disk (DVD) drive, flash memory, memory stick, transistor-based memory or other computer-readable memory device as is known in the art for storing and retrieving data. 
     Turning to the functional elements contained within central processing unit  3100 , central processing unit  3100  comprises mast controller  3200 , data processor  3300 , and application interface  3400 . Mast controller  3200  further comprises position monitor  3202  and drive control unit  3204 . It is well understood by those in the art, that these functional elements may be implemented in hardware, firmware, or as software instructions and data encoded on a computer-readable storage medium. 
     Data processor  3300  interfaces with storage medium, electric motor  2040 , and position feedback sensor  2030 . The data processor  3300  enables mast controller  3200  to locate data on, read data from, and send data to, these components. 
     Application interface  3400  enables central processing unit  3100  to take some action with respect to a separate software application or entity. For example, application interface  3400  may take the form of a windowing or other user interface, as is commonly known in the art. 
     The function of position monitor  3202  and drive control unit  3204  are described below. 
       FIG. 4  is a flow chart of a process  4000  to control the extension and retraction of a telescoping mast without jar, coming in a smooth stop (also known as a “soft landing”) in accordance with an embodiment of the present invention. Soft landings help prevent damage to sensitive payloads  1100 , such as cameras, radio-frequency antennas, microwave television broadcast antennas, cellular phone towers, satellite communication dishes, and the like. 
     Initially, a user sets the desired position of the telescoping mast  1000 . In some embodiments, telescoping mast  1000  may simply be set to extended or retracted positions. In other embodiments, variable telescoping mast  1000  heights may be specified, where the height is set in between the fully extended or fully retracted positions. In either case, the application interface  3400  reads the set position at block  4002 . 
     Position monitor  3202  reads the actual (or “current”) mast position, block  4004 . In some embodiments, the extension and retraction of mast  1000  is measured by resistance or voltage fed into an analog-to-digital converter. In such embodiments, mast position may be indicated as a voltage on a variable resistor or potentiometer. 
     When the mast set position is greater than the actual position, as determined by mast controller  3200 , flow continues at decision block  4008 . Otherwise, flow continues at decision block  4014 . 
     At decision block  4008 , if the actual mast position is close to the set position, drive control unit  3204  decelerates electric motor upward, block  4010 . If the actual mast position is not close to the set position, drive control unit  3204  accelerates electric motor upward, block  4012 . 
     At block  4022 , the mast controller  3200  compensates for movement by spring motor  2080 . 
     When the mast set position is less than the actual position, as determined by mast controller  3200  at decision block  4014 , flow continues at decision block  4016 . 
     At decision block  4016 , if the actual mast position is close to the set position, drive control unit  3204  decelerates electric motor downward, block  4018 . If the actual mast position is not close to the set position, drive control unit  3204  accelerates electric motor downward, block  4020 . 
     When the mast set position not less than the actual position, as determined by mast controller  3200  at decision block  4014 , drive control unit  3204  disables the motor  2040 , stopping mast movement at block  4024 . 
     The previous description of the embodiments is provided to enable any person skilled in the art to practice the invention. The various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.