Abstract:
According to an embodiment, an audio equipment includes a housing, a radio tuner circuit disposed within the housing, a first helical antenna disposed within the housing, a second helical antenna disposed within the housing, the first and second helical antennae each having a circular polarization, a switch connected to the first and second helical antennae arranged to connect one of the first and second helical antennae to the radio tuner circuit, and a controller arranged to control the switch for selection between the first and second helical antennas.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 62/248,624, filed on Oct. 30, 2015, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    It is well known that audio equipment, such as portable radios, are taken to construction sites, so that the construction workers can listen to music, talk shows, etc., while working. However, the audio equipment may be destroyed at the jobsite because tools may be dropped on them. Similarly, the equipment may fall from a table, etc., resulting in damage thereto. 
         [0003]    Furthermore, because construction workers have different cordless power tools, it would be beneficial if the audio equipment would receive the rechargeable battery packs used with the power tools in order to charge the battery packs and/or power the audio equipment. 
         [0004]    U.S. Pat. Nos. 6,427,070 and 6,308,059, which are hereby incorporated by reference, disclose a heavy-duty audio equipment that can charge power tool battery packs and that can withstand the rigors of the jobsite. 
       SUMMARY 
       [0005]    According to an embodiment, an audio equipment comprises a housing, a radio tuner circuit disposed within the housing, first and second helical antennae disposed within the housing, the first and second helical antennae having a circular polarization, and a switch connected to the first and second helical antennae for connecting one of the first and second helical antennae to the radio tuner circuit. A plate antenna and/or a wire may be connected to the ground. The plate antenna and/or wire antenna are disposed within the housing. 
         [0006]    According to an embodiment, an audio equipment includes a housing, a radio tuner circuit disposed within the housing, a first helical antenna disposed within the housing, a second helical antenna disposed within the housing, the first and second helical antennae each having a circular polarization, a switch connected to the first and second helical antennae arranged to connect one of the first and second helical antennae to the radio tuner circuit, and a controller arranged to control the switch for selection between the first and second helical antennas. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]      FIG. 1  is a perspective view of a heavy-duty audio equipment. 
           [0008]      FIG. 2  is a cross-sectional view of the audio equipment shown in  FIG. 1  along plane B-B-B. 
           [0009]      FIG. 3  is a block diagram showing the main components of the audio equipment shown in  FIG. 1 . 
           [0010]      FIG. 4  is a top plan view of the audio equipment shown in  FIG. 1 . 
           [0011]      FIG. 5  is a block diagram showing an antennae configuration for the audio equipment shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring to  FIGS. 1-3 , an audio equipment component, such as radio  10 , of the present invention comprises a housing  11 . Housing  11  is preferably made of a rigid material, such as plastic and in particular ABS, and has a bottom wall  11 W to support the radio  10  on the ground or support surface. Resilient, impact-absorbing material, such as elastomer or rubber, may be disposed on housing  11  in an overmolding process. 
         [0013]    Housing  11  may have a handle  11 H for carrying radio  10 . Housing  11  may be latched unto or engaged with a storage assembly, such as that disclosed in U.S. Pat. No. 8,567,796, which is fully incorporated herein by reference. 
         [0014]    Housing  11  may support audio circuitry, such as a radio tuner circuit  21 , a BlueTooth® audio input circuit  22  and/or an auxiliary input  23 . Persons skilled in the art will recognize that radio tuner circuit  21  can include any circuitry necessary to demodulate AM, FM, digital audio broadcast (DAB) and/or satellite radio signals. Radio tuner circuit  21  may include a Keystone Semiconductor T2_L4_8650C DAB/FM module, for example. In addition persons skilled in the art shall recognize that audio circuitry may include other circuitry for producing audio signals via circuitry used with a cassette deck, compact disk, MP3 players or other methods to play music. 
         [0015]    The audio circuitry is preferably connected to amplifier  24  for amplifying the audio signals. Housing  11  may also support speakers  25 S and/or sub-woofers  25 SW, which are preferably connected to amplifier  24  for converting the, amplified signal into audible signals. 
         [0016]    Radio tuner circuit  21  and/or BlueTooth® audio input  22  may be connected to and/or controlled by a controller  26 . Controller  26  is also preferably connected to a charger circuitry  27  for charging power tool battery packs  100 . 
         [0017]    Preferably radio tuner circuit  21  has at least one antenna connected thereto. Two helical antennae  21 H may be disposed within housing  11 , preferably adjacent to handle  11 H. Each helical antenna  21 H may be between about 7 centimeters and about 15 centimeters in overall length. Preferably, each helical antenna  21 H is about 13 centimeters and about 15 centimeters in overall length, and is preferably about 14.5 centimeters long in the operating helical configuration. Each helical antenna  21 H may have a diameter between about 0.5 centimeters and 2 centimeters (preferably being about 16 millimeters), and a longitudinal axis. Persons skilled in the art will recognize that, if the helical antenna  21 H were stretched linearly, the overall length would be between about 45 centimeters and 90 centimeters long. Preferably the longitudinal axes of the helical antennae  21 H are substantially coaxial, and horizontal when housing  11  is disposed on the position shown in  FIG. 1 , i.e., with the bottom wall  11 W on the ground or support surface. 
         [0018]    A plate antenna  21 P may be provided within housing  11  along one side of housing  11 . Plate antenna  21  P is preferably made of aluminum. Preferably plate antenna  21 P is between about 15 centimeters and about 25 centimeters long (preferably about 23.2 centimeters long) and about 4-8 centimeters wide (preferably about 7 centimeters wide). The longitudinal axis of plate antenna  21 P may be substantially horizontal when housing  11  is disposed on the position shown in  FIG. 1  and thus substantially perpendicular to the longitudinal axes of the helical antennae  21 H. 
         [0019]    A wire antenna  21 W may be provided within housing  11  along one side of housing  11 . Wire antenna  21 W may be made of 24 gauge (AWG) wire having a length between about 15 centimeters and about 25 centimeters long (preferably about 25 centimeters long). Persons skilled in the art will recognize that wire antenna  21 W may be made of wire as thick as 22 gauge. The longitudinal axis of wire antenna  21 W may be substantially horizontal when housing  11  is disposed on the position shown in  FIG. 1  and thus substantially perpendicular to the longitudinal axes of the helical antennae  21 H. 
         [0020]    Persons skilled in the art will recognize that it is preferable to dispose helical antennae  21 H, plate antenna  21 P and/or wire antenna  21 W within housing  11  so that they are well protected against the rigors of the construction jobsite. It is preferable to dispose helical antennae  21 H, plate antenna  21 P and/or wire antenna  21 W completely within housing  11 . 
         [0021]    Persons skilled in the art shall recognize that antenna(e) typically have a vertical polarization, a horizontal polarization, a left hand circular (or mixed) polarization, a right hand circular (or mixed) polarization, etc., and that the polarization of the antenna(e) is typically selected to match the polarization of the broadcast signal. Accordingly, in order to receive FM or DAB broadcast signals, which have a vertical polarization, it would be typical to use a vertically polarized antenna. Rather than use vertically polarized antennae, the helical antennae  21 H preferably have a circular polarization (preferably a right hand circular polarization), and plate antenna  21 P and wire antenna  21 W preferably have a horizontal polarization. 
         [0022]    Radio tuner circuit  21  may have a switching circuit  21 S for selecting the antenna input. Persons skilled in the art will recognize that the switching circuit  215  may be controlled by controller  26  or radio tuner circuit  21 . The helical antennae  21 H may be connected to the switching circuit  21 S for selecting between the two. Plate antenna  21 P and/or wire antenna  21 W may be connected to radio tuner circuit  21 , switching circuit  21 S and/or ground. 
         [0023]    Persons skilled in the art will recognize that the helical antennae  21 H have two leads. One lead of the left helical antenna  21 H is preferably unconnected. The other lead of left helical antenna  21 H is connected to the switching circuit  21 S and/or radio tuner circuit  21 . Similarly, one lead of the right helical antenna  21 H is preferably unconnected, while the other lead of the right helical antenna  21 H is connected to the switching circuit  21 S and/or radio tuner circuit  21 . The plate antenna  21 P and wire antenna  21 W are connected to ground, which in turn is connected to a ground in radio tuner circuit  21 . Such connection schemes effectively create two compound array antennae with substantially perpendicular elements. 
         [0024]    In a preferred embodiment shown in  FIG. 5 , one lead of the left helical antenna  21 H is unconnected while the other lead may be connected to a middle core  30 C of a first coaxial cable  30 , preferably a 50 ohm coaxial cable. The plate antenna  21 P is preferably connected to the ground shield  30 S of the first coaxial cable  30 . The first coaxial cable  30  in turn may be connected to switching circuit  21 S and/or radio tuner circuit  21 . For example, the middle core would be connected to an antenna port of T2_L4_8650C DAB/FM module, while the ground is connected to the plate antenna  21 P. 
         [0025]    Similarly, one lead of the right helical antenna  21 H is unconnected while the other lead may be connected to a middle core  30 C of a second coaxial cable  30 , preferably a 50 ohm coaxial cable. The wire antenna  21 W is preferably connected to the ground shield  30 S of the second coaxial cable  30 . The second coaxial cable  30  in turn may be connected to switching circuit  21 S and/or radio tuner circuit  21 . For example, the middle core  30 S would be connected to an antenna port of T2_L4_8650C DAB/FM module, while the ground is connected to the wire antenna  21 W. Persons skilled in the art will recognize that the first and second coaxial cables  30  may be isolated. Persons skilled in the art will recognize that the helical antennae  21 H may alternatively be connected to the ground shield  30 S of their respective coaxial cables  30 , while the wire and plate antennae  21 W,  21 P may be connected to the middle core  30 C of their respective coaxial cable. 
         [0026]    One method for selecting the antenna input may be selecting a default antenna, such as the left helical antenna  21 H. The strength of the signal received by such antenna is measured and averaged for a predetermined period of time, such as 3 seconds. Similarly the bit error rate of a DAB signal may be calculated and averaged for a predetermined period of time, such as 3 seconds. If the signal strength is below a predetermined threshold and/or the bit error rate is higher than a predetermined threshold (e.g., 70%), the switching circuit  21 S would select another antenna, such as the right helical antenna  21 H. 
         [0027]    The strength of the signal received by such antenna is measured and averaged for a predetermined period of time, such as 3 seconds. Similarly the bit error rate of a DAB signal may be calculated and averaged for a predetermined period of time, such as 3 seconds. If the signal strength is below a predetermined threshold and/or the bit error rate is higher than a predetermined threshold (e.g., 70%), controller  26  may provide an “error” or “low signal” message on display  26 D. 
         [0028]    With such arrangement, antenna reception is relatively uniform regardless of the orientation of housing  11 . In this regard, “orientation” refers to the position of radio  10  relative to a vertical axis VA, where the radio  10  is originally disposed in the orientation shown in  FIG. 1 . In other words, the orientation of radio  10  refers to the rotational position of radio  10  relative to vertical axis VA, such as the rotational position shown in  FIG. 1 . 
         [0029]    Persons skilled in the art will understand that the present arrangement allows a user can rotate radio  10  360 degrees with minimal signal strength differential. For example, if the maximum signal strength received via the antennae is around 48 dB and the average signal strength around the different rotational positions is about 44.4 dB, the maximum drop in signal strength throughout the full rotation of radio  10  will be about 4-5 dB from the average signal strength, which is a drop of about 9% and about 11% of the average signal strength. Furthermore, the maximum drop in signal strength throughout the full rotation of radio  10  will be about 8 dB from the maximum signal strength, which is about 16% of the maximum signal strength. 
         [0030]    Charger circuitry  27  may receive power from an alternating current source via connector  27 C. Charger circuitry  27  may provide power to the power tool battery pack  100  for charging such battery pack. Persons skilled in the art are referred to U.S. Pat. No. 8,653,787, which is incorporated herein by reference, for further information on charger circuitry  27  and power tool battery pack  100 . 
         [0031]    Charger circuitry  27  may provide power to a power supply circuit  28 , which could provide power to the other circuits in radio charger  10 , as well as power to a USB port  29 . The power provided by charger circuitry  27  may originate from the alternating current source connected to connector  27 C (and preferably regulated and converted to direct current), and/or from a power tool battery pack  100  connected to charger circuitry  27 . In other words, the audio circuitry and amplifier  24  may be ultimately powered by the alternating current source and/or a power tool battery pack  100 . 
         [0032]    Charging circuit  27  may have a switching mechanism  27 S to select the appropriate power source. For example, switching mechanism  27 S would select whether the alternating current source or power tool battery pack  100  provides power to the power supply circuit  28 . Switching mechanism  27 S may comprise relays, transistors or other switching devices as is well known in the art. Preferably power supply circuit  28  can accept power from power tool battery packs  100  having different nominal voltages. 
         [0033]    Sometimes charging circuit  27  may emit interfering signals that are received by the antennae  21 H,  21 W,  21 P. Preferably shielding is provided around charging circuit  27  to minimize the emission of such interfering signals. 
         [0034]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the scope of the invention.