Patent Publication Number: US-11646169-B2

Title: Rolling-ball tilt switch

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Taiwanese Invention Patent Application No. 110126765, filed on Jul. 21, 2021. 
     FIELD 
     The disclosure relates to a tilt switch, and more particularly to a rolling-ball tilt switch. 
     BACKGROUND 
     Referring to  FIG.  1   , Taiwanese Invention Patent No. TWI390563B discloses a conventional rolling-ball tilt switch  9 , including a conductive housing  91 , two rolling-balls  92 , an insulating seat  93  and an electric terminal  94 . The conductive housing  91  has an outer surface  911  that surrounds a central axis (C), an inner surface  913  that surrounds the central axis (C) and that defines a roller cavity  912 , a rim surface  914  that interconnects the inner surface  913  and the outer surface  911  and that defines an opening  916  communicating with the roller cavity  912 , and an enclosed part  915  that is opposite to the rim surface  914  along the central axis (C) and that is connected between the inner surface  913  and the outer surface  911 . The two rolling-balls  92  are electrically conductive and disposed in the roller cavity  912 , and are contained therein. The insulating seat  93  is installed on the conductive housing  91  so that the two rolling-balls  92  are contained within the roller cavity  912 . The electric terminal  94  extends through the insulating seat  93  along the central axis (C) so as to cooperate with the insulating seat  93  to block the opening  916 , and a tip of the electric terminal protrudes into the roller cavity  912 . If the conventional rolling-ball tilt switch  9  is tilted so that at least one of the two rolling-balls  92  is concurrently in contact with the electric terminal  94  and the conductive housing  91 , the conventional rolling-ball tilt switch  9  will be in a conducting state. Conversely, when both of the two rolling-balls  92  are separated from the electric terminal  94 , the conventional rolling-ball tilt switch  9  will be in a non-conducting state. 
     Under a scenario where the conventional rolling-ball tilt switch  9  is placed parallel to a ground surface while remaining in the conducting statae, even a slight tilt causing a small change in angle relative to the ground surface may cause the conventional rolling-ball tilt switch  9  to switch to the non-conducting state. Therefore, the conventional rolling-ball tilt switch  9  is too sensitive to small angle adjustments and does not have the tolerance required to operate under a designated range of tilt angles. This makes the conventional rolling-ball tilt switch  9  unsuitable for many applications. 
     SUMMARY 
     Therefore, an object of the disclosure is to provide a rolling-ball tilt switch that can remain in a conducting state under a range of tilt angles. 
     According to the disclosure, a rolling-ball tilt switch is adapted to be electrically connected to a circuit board that is on a reference surface. The rolling-ball tilt switch includes a conductive housing, an insulating seat, a conductive terminal, and a ball unit. 
     The conductive housing is adapted to be secured to the circuit board, and has an inner surface, an outer surface, a rim end surface, and a distal end surface. The inner surface is adapted to surround a longitudinal axis parallel to the circuit board, and defines a roller cavity. The outer surface surrounds and is opposite to the inner surface. The rim end surface interconnects the inner surface and the outer surface. The distal end surface interconnects the inner surface and the outer surface, and is opposite to the rim end surface along the longitudinal axis. The inner surface has a first surface portion that is adjacent to the rim end surface, and a second surface portion that extends from the first surface portion along the longitudinal axis towards the distal end surface. The second surface portion has a first section connected to the first surface portion and gradually converging towards the distal end surface, and a second section connected to an end of the first section which is opposite to the first surface portion, and gradually converging towards the distal end surface. 
     The longitudinal axis and an extension of the first section of the second surface portion of the inner surface cooperatively define a first angle that ranges from 2 to 12 degrees. The longitudinal axis and an extension of the second section of the second surface portion of the inner surface cooperatively define a second angle that is not larger than 90 degrees and that is larger than the first angle. 
     The insulating seat is connected to the rim end surface and is fittingly inserted into the roller cavity. 
     The conductive terminal has a protruding section extending through the insulating seat into the roller cavity and cooperating with the insulating seat to seal an end of the roller cavity adjacent to the rim end surface; and 
     The ball unit is disposed in the roller cavity, and is movable along the second surface portion between a conducting position, where the ball unit is concurrently in contact with the protruding section of the conductive terminal and the second surface portion, and a non-conducting position, where the ball unit is separated from the protruding section of the conductive terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which: 
         FIG.  1    is a sectional view illustrating a conventional rolling-ball tilt switch disclosed in Taiwanese Patent No. TWI390563B; 
         FIG.  2    is a side view illustrating a first embodiment of a rolling-ball tilt switch according to the present disclosure; 
         FIG.  3    is an exploded perspective view illustrating the first embodiment of the rolling-ball tilt switch; 
         FIG.  4    is a sectional view illustrating the first embodiment in a conducting position; 
         FIG.  5    is a sectional view illustrating the first embodiment in a non-conducting position; 
         FIG.  6    is a sectional view illustrating a second embodiment of the rolling-ball tilt switch in the conducting position; and 
         FIG.  7    is a sectional view illustrating the second embodiment in the non-conducting position. 
     
    
    
     DETAILED DESCRIPTION 
     Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics. 
     Referring to  FIGS.  2  to  5   , a first embodiment of a rolling-ball tilt switch  201  according to the present disclosure is adapted to be electrically connected to a circuit board  7  that is on a reference surface  8 , and includes a conductive housing  2 , an insulating seat  3 , a conductive terminal  4 , a ball unit  5 , and a plugging sphere  6 . 
     The conductive housing  2  is adapted to be secured to the circuit board  7 , and has an inner surface  22 , an outer surface  23 , a rim end surface  24 , and a distal end surface  25 . The inner surface  22  is adapted to surround a longitudinal axis (L) parallel to the circuit board  7 , and defines a roller cavity  21 . The outer surface  23  surrounds and is opposite to the inner surface  22 . The rim end surface  24  interconnects the inner surface  22  and the outer surface  23 . The distal end surface  25  interconnects the inner surface  22  and the outer surface  23 , and is opposite to the rim end surface  24  along the longitudinal axis (L). 
     The inner surface  22  has a first surface portion  221  that is cylindrical and that is adjacent to the rim end surface  24 , and a second surface portion  222  that extends from the first surface portion  221  along the longitudinal axis (L) towards the distal end surface  25 . The second surface portion  222  has a first section  225  connected to the first surface portion  221  and gradually converging towards the distal end surface  25 , and a second section  226  connected to an end of the first section  225  which is opposite to the first surface portion  221 , and gradually converging towards the distal end surface  25 . The longitudinal axis (L) and an extension of the first section  225  of the second surface portion  222  of the inner surface  22  cooperatively define a first angle (θ 1 ) that ranges from 2 to 12 degrees. The longitudinal axis (L) and an extension of the second section  226  of the second surface portion  222  of the inner surface  22  cooperatively define a second angle (θ 2 ) that is not larger than 90 degrees and that is larger than the first angle (θ 1 ). It should be noted that in some embodiments the second angle (θ 2 ) may range from 60 to 80 degrees. More specifically, in the first embodiment, the first angle (θ 1 ) is substantially 4 degrees, and the second angle (θ 2 ) is substantially 60 degrees. 
     The insulating seat  3  is connected to the rim end surface  24 , and has a base body  31  that surrounds the longitudinal axis (L), and an insertion hole  32  that extends along the longitudinal axis (L) through the base body  31 . The base body  31  has an annular plug section  311  that is fittingly inserted into the roller cavity  21  of the conductive housing  2  and that abuts against the first surface portion  221  of the inner surface  22 , and an annular sealing section  312  that is connected to the annular plug section  311 , that has a diameter larger than that of the annular plug section  311  and that abuts against the rim end surface  24 . The insertion hole  32  is a stepped hole, and has a large hole section  321  that is formed in the annular sealing section  312  of the base body  31 , and a small hole section  322  that has a diameter smaller than a diameter of the large hole section  321 , and that extends from the large hole section  321  through the annular plug section  311  of the base body  31  into the roller cavity  21 . 
     The conductive terminal  4  has a terminal head  42  that is fittingly inserted into the large hole section  321  of the insertion hole  32 . The conductive terminal  4  further has a protruding section  41  extending from the terminal head  42  through the insulating seat  3  into the roller cavity  21  and cooperating with the insulating seat  3  to seal an end of the roller cavity  21  adjacent to the rim end surface  24 . More specifically, the terminal head  42  has a diameter larger than that of the protruding section  42 , and the protruding section  41  extends from the terminal head  42  through the small bore section  322  of the insertion hole  31  into the roller cavity  21 . 
     Referring to  FIGS.  4  and  5   , in this embodiment, the ball unit  5  is configured as a conductive rolling ball and is disposed in the roller cavity  21 . The ball unit  5  is movable along the second surface portion  222  of the inner surface  22  between a conducting position (see  FIG.  4   ), where the ball unit  5  is concurrently in contact with the protruding section  41  of the conductive terminal  4  and the second surface portion  222 , and a non-conducting position (see  FIG.  5   ), where the ball unit  5  is separated from the protruding section  41  of the conductive terminal  4 . 
     During manufacturing of the rolling-ball tilt switch  201 , an electroplating process is used on the rolling-ball tilt switch  201 . The inner surface  22  of the conductive housing  2  further has a third surface portion  223  that extends from the second section  226  of the second surface portion  222  along the longitudinal axis (L) to the distal end surface  25 , and that defines an oculus  227 . The oculus  227  prevents electroplating solution from accumulating in the conductive housing  2  by providing an outlet for the electroplating solution to drain out. The plugging sphere  6  is disposed in the oculus  227  and seals the oculus  227  after the electroplating process. 
     In this embodiment, the rolling-ball tilt switch  201  has the conductive terminal  4  cooperating with the insulating seat  3  to seal the end of the roller cavity  21  adjacent to the rim end surface  24 , and the plugging sphere  6  to seal the oculus  227 , thereby sealing opposite ends of the roller cavity  21 . This creates an airtight and watertight seal so that the roller cavity  21  of the conductive housing  2  is isolated from the external environment, and the ball unit  5  therein can be protected from corrosion and rust. 
     When the rolling-ball tilt switch  201  is to be used, it is electrically connected to the circuit board  7  and placed on the reference surface  8 . In the first embodiment, when the rolling-ball tilt switch  201  is placed in a state where the longitudinal axis (L) is parallel to the reference surface  8 , the ball unit  5  is in the conducting position. When the rolling-ball tilt switch  201  and the circuit board  7  are tilted relative to the reference surface  8  to another state where the longitudinal axis (L) is tilted at an angle of more than 4 degrees relative to the reference surface  8 , the ball unit  5  will then move to the non-conducting position to be separated from the protruding section  41  of the conductive terminal  4 . When the rolling-ball tilt switch  201  is tilted at an angle of less than 4 degrees relative to the reference surface  8 , the ball unit  5  will remain to be in the conducting position. Therefore, the rolling-ball tilt switch  201  according to the present disclosure can remain in the conducting state under a range of tilt angles. 
     Referring to  FIG.  4   , the first section  225  and second section  226  of the second surface portion  222  form a third angle (θ 3 ) that ranges from 110 to 130 degrees. In this embodiment, the third angle (θ 3 ) is equal to the value of the first angle (θ 1 ) plus 180 degrees then subtracted by the second angle (θ 2 ). In this embodiment, the third angle (θ 3 ) is substantially 124 degrees; the function of the third angle (θ 3 ) is to prevent the ball unit  5  from being stuck between the first section  225  and the second section  226  of the second surface portion  222  so that the ball unit  5  can smoothly transition from the conducting position to the non-conduction position. 
     Referring to  FIGS.  6  and  7   , a second embodiment of the rolling-ball tilt switch  201  according to the disclosure is shown. The second embodiment is similar to the first embodiment, and the difference between the first embodiment and the second embodiment lies in the ball unit  5 . In the second embodiment, the ball unit  5  includes a large conductive ball  51 , and a small conductive ball  52  that is disposed between the large conductive ball  51  and the distal end surface  25  of the conductive housing  2 , and that is smaller than the large conductive ball  51 . In the second embodiment, when the ball unit  5  is in the conducting position, the large conductive ball  51  is concurrently in contact with the small conductive ball  52 , the protruding section  41  of the conductive terminal  4 , and the second surface portion  222  of the inner surface  22  of the conductive housing  2 . When the ball unit  5  is in the non-conducting position, the large conductive ball  51  is separated from the protruding section  41  of the conductive terminal  4 . The second embodiment can accomplish the same goals and achieve the same effects as the first embodiment. 
     In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure. 
     While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that this disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.