Abstract:
A tilt switch comprises an insulating housing, a cover covering the opening of the housing, three terminals fixed at the bottom of the housing and an electrically conductive ball movably received in the housing to on/off the switch by contacting/leaving said terminals. Three terminals are located at each vertex position of a triangle such that one terminal having a polarity opposite to the other two terminals and a protruding length longer than those of the other two terminals, allowing elevation difference to exist between them.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    a) Field of the Invention 
         [0002]    The present invention relates to a tilt switch, and more particularly to a tilt switch which is installed on all kinds of machines including an electronic machine, a control device, or a measurement machine, for detecting their tilt or vibration. 
         [0003]    b) Description of the Prior Art 
         [0004]    A ball member vibration switch, as disclosed by the Taiwanese Utility Model Patent No. 468865, includes an insulating housing, an interior of which is provided with an electrically conductive metal ball member and a plurality of electrically conductive terminals. By tilt of the insulating housing, the ball member will move between positions where the ball member is and is not in contact with the terminals, to perform an ON/OFF operation of the switch, so as to detect the tilt or vibration of a machine which is installed with this switch. 
         [0005]    Referring to  FIGS. 9 to 11 , this switch is provided with an insulating housing  10 , an opening part of which has a larger diameter, and a bottom part of which is formed with an accommodating space  101  in a shape of a funnel. An electrically conductive ball member  102  is movable and accommodated in an interior of the accommodating space  101  of the insulating housing  10 , two pairs of electric contact members t 1 , t 2  which have opposite polarities, are protruded from an inner side at the bottom of the insulating housing  10 , and a cap  104  covers the opening part of the insulating housing  10 . 
         [0006]    Referring to  FIG. 9 , this kind of switch is usually installed on a target machine horizontally. In this situation, the ball member  102  is located in the large-diameter part of the accommodating space  101  without contacting the contact members t 1 , t 2 , and the switch is at an OFF state. If the insulating housing  10  is lifted upward at an end of the cap  104  from this horizontal state, allowing the switch to tilt as shown in  FIG. 10 , then the ball member  102  will roll toward the left side funnel part, due to its weight. When a tilt angle of the switch exceeds 45 degrees, the ball member  102  will fall into the funnel part to contact the four contact members t 1 , t 2 , thereby constituting an ON state. Accordingly, by the movement of the ball member, and the extent of tilting of the switch, the ON/OFF operation can be carried out. 
         [0007]    In addition, the Japanese Utility Model Patent No. 9-7475 discloses an inclination detection switch which includes an insulating substrate, a plurality of terminals inserted into terminal holes on the insulating substrate, a case-shape housing which covers this insulating substrate, and an electrically conductive ball member which is movable and contained in an interior of the housing, wherein contact parts at top ends of the terminals are formed with knife-like edges, and the ball member crosses over the knife-like edges, thereby reducing contact area of the ball member with the knife-like edges to increase contact pressure per unit area. 
         [0008]    Furthermore, the Japanese Utility Model Patent No. 11-232973 discloses a direction detection type inclination switch, which consists of a base with a top face being in a funnel shape, at least one or more light-emitting elements arranged in a center of the funnel-like part for emitting light toward an upper part of the base, a plurality of light-receiving bodies arranged around the light-emitting element, a light shielding ball which is freely movable and mounted on the base, and a cap which accommodates this light shielding ball and covers an inner surface of the base for forming a reflection face. The inclination switch constituted in such a manner can detect the inclination direction by shielding the light receiving body in front of the moving direction, due to the free movement of the light shielding ball in the inclined direction. 
         [0009]    However, for the switch which is disclosed by the Taiwanese Utility Model Patent No. 468865, the bottom part of its insulating housing needs to form the cone-shape funnel part at about 45 degrees, and the ON and OFF operations of the switch are dependent upon whether the tilt angle of the switch exceeds 45 degrees; that is, the tilt angle of 45 degrees is a critical angle for the operation of the switch. At this critical angle of 45 degrees, vertical component of force of the electrically conductive ball member is identical to its horizontal component of force; therefore, the ball member is under an unstable condition, and the switch is easy to manifest an intermittent and non-steady ON/OFF state. In addition, as the ball member is supported by the front ends of two pairs of contact members that are configured on a same plane, it is easy to form unstable condition that maintaining the stable operation for the switch will be difficult, if only slight tilt or vibration occurs. Moreover, as the operation angle of the switch is fixed at 45 degrees, this angle cannot be changed or adjusted. 
         [0010]    For the detection switch disclosed by the Japanese Utility Model Patent No. 9-7475, as the contact end of the terminal is formed with the knife-like shape, the structure of terminal will become complicated. At a same time, the operation angle of the switch cannot be changed freely, either. 
         [0011]    On the other hand, the switch disclosed by the Japanese Utility Model Patent No. 11-232973 includes the light-emitting element and a plurality of light receiving bodies, whereas the inner surface of the cap is formed with the reflection surface. Therefore, when the switch tilts, the ball member will roll to shield the light receiving body in the rolling direction, such that the light receiving body is not irradiated by the light, and is thus not operable, thereby detecting the inclination direction of the switch. This kind of switch has a complicated structure and high manufacturing cost. In a mean time, its construction is not the same as the construction and principle for turning on and off the tilt switch by directly contacting the ball member with the terminals, as disclosed by the aforementioned Taiwanese Utility Model Patent No. 468865 and the Japanese Utility Model Patent No. 9-7475. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, the present invention is developed to solve the aforementioned problems, and the primary object of the present invention is to provide a tilt switch which is supported by three points from three terminals with elevation difference for easily gaining mechanics balance, if an electrically conductive ball member of which is at an ON state, so as to decrease an intermittent electric conduction phenomenon upon performing an ON/OFF operation at a critical angle. In a mean time, the switch is constructed that its operation angle (tilt angle) is easily changed or adjusted, that it is provided with a good operability and a simple structure, as well as that it is easily assembled. 
         [0013]    Accordingly, the tilt switch of the present invention includes an insulating housing, an end of which is provided with an opening, the other end of which is a closed bottom, and which is in a case shape; a cap, which covers the opening of the aforementioned insulating housing; a plurality of terminals which are parallel transfixed into terminals holes at the bottom of the aforementioned housing, with one end of each of which being protruded into an interior of the housing, and the other end of each of which being protruded out of the bottom; and an electrically conductive ball member, which is freely movable and accommodated in an interior of the aforementioned housing, as well as serves as a movable contact. By tilt of the insulating housing, the electrically conductive ball member rolls to contact and remove from the protrusion ends in the housing to proceed with the switching operation. There are three terminals which are located at the bottom of the aforementioned housing and are aligned in a triangular shape, wherein one terminal has a polarity opposite to those of the other two terminals, and one terminal protrudes inward to the housing by a section longer than those of the other two terminals, allowing elevation difference to exist between that terminal and the other two terminals. Accordingly, when the aforementioned housing tilts to enable the electrically conductive ball member to contact the aforementioned three terminals, the electrically conductive ball member will be at a stable contact state, due to that the three terminals maintain the balance state. 
         [0014]    In the switch of the present invention, the aforementioned triangle formed by the installation locations of those three terminals is usually an equilateral triangle or an isosceles triangle, with diameter of its circumscribed circle being smaller than diameter of the aforementioned electrically conductive ball member. 
         [0015]    Furthermore, at least one aforementioned terminal of the three terminals in the present invention is configured as that its protrusion length in the insulating housing can be freely adjusted relative to the aforementioned insulating housing. Also in the present invention, a central part of an inner wall of the insulating housing, facing one terminal, is provided with a conductive member which faces to and is parallel to the terminal, so as to change thickness of the conductive member for adjusting the ON/OFF tilt angle of the switch. This conductive member can be formed integrally with the insulating housing or can be freely assembled with or disassembled from the housing. 
         [0016]    To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  shows an exploded view of a first embodiment of a tilt switch of the present invention. 
           [0018]      FIG. 2  shows a partial cutaway view of an assembly state of  FIG. 1 . 
           [0019]      FIG. 3  shows an end view of a switch after dismantling a cap, according to  FIG. 1 . 
           [0020]      FIG. 4  shows a cutaway view of a usage state when a switch of a first embodiment is at an OFF position. 
           [0021]      FIG. 5  shows a cutaway view of a usage state when a switch of  FIG. 4  is at an ON position. 
           [0022]      FIG. 6  shows a cutaway view of a usage state of a second embodiment of a tilt switch of the present invention. 
           [0023]      FIG. 7  shows a cutaway view of another usage state of a switch of  FIG. 6 . 
           [0024]      FIG. 8  shows an exploded view of two embodiments that a conductive member is assembled with an insulating housing. 
           [0025]      FIG. 9  shows a cutaway view of an embodiment of a conventional tilt switch. 
           [0026]      FIG. 10  shows an end view of a switch after dismantling a cap, according to  FIG. 9 . 
           [0027]      FIG. 11  shows a cutaway view of a usage state of a switch of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    A first embodiment of a tilt switch of the present invention is described with  FIGS. 1 to 3 . Referring to  FIG. 1 , it shows an exploded view of the first embodiment of the tilt switch of the present invention, wherein a tilt switch S includes a case-shape insulating housing  1 , an end of which is provided with an opening  11 ; a cap  2  which covers the opening  11  of the housing  1 ; three terminals T which are inserted at a bottom  12  of the housing  1 ; and an electrically conductive ball member  3  which is freely movable and accommodated in an interior of the housing  1 . 
         [0029]    Referring to  FIG. 2 , it shows a partial cutaway view of a state that the switch S is transversally installed on an electronic machine M, after being assembled.  FIG. 3  shows an end view of the switch S after the cap  2  is dismantled. It can be seen from  FIG. 2  and  FIG. 3  that the three terminals T are mutually parallel with one another, at each vertex position of a triangle which is formed by connecting the vertexes with straight lines, upon installing the three terminals T. 
         [0030]    In this embodiment, one terminal T 1  at a lower side position of the housing  1  is inserted into a terminal hole  1   a  at the bottom  12  of the housing  1 , corresponding to a vertex position of an inverted triangle; whereas, two other terminals T 2  at upper side positions are inserted into the terminal holes  1   a  at the bottom  12 , corresponding to two end positions of a bottom edge of the aforementioned inverted triangle, with the terminal T 1  having an opposite polarity to the terminals T 2 . For example, if the polarity of the terminal T 1  is positive, then the other two terminals T 2  are negative. On the contrary, if the terminal T 1  is negative, then the terminals T 2  will be positive. However, this setting is not restricted; for example, if the terminal T 1  is positive or negative, then the two terminals can have two different polarities, with one terminal being positive, and the other terminal being negative. 
         [0031]    Inner diameter of the housing  1  is larger than diameter of the electrically conductive ball member  3  which is accommodated in the interior of the housing  1  to serve as a movable contact. Therefore, the ball member  3  can roll freely inside the housing  1 . In addition, diameter of a circumscribed circle of the triangle formed by three fixing terminals T 1 , T 2 , T 2 , is smaller than the diameter of the electrically conductive ball member  3 . Therefore, when the switch is ON, the terminals can support a lower hemisphere underneath the diameter of the ball member  3  by three points. Furthermore, an inner wall of the housing  1  that is close to a central part of a wall  13  of the terminal T 1 , is integrally formed with a protruded guide member  14  which extends from the opening  11  along the terminal T 1  side (that is, along axis direction) toward the bottom  12  or its proximity. By this conductive member  14 , the ball member  3  can be guided to quickly move to a front end of the terminal T 1 . The guide member  14  is formed as a rectangular plate or rib, with its upper surface being a plane or arc cross section. 
         [0032]    There is no special limitation to the cap  2  for closing the opening  11  of the housing  1 , as long as that it can seal the opening  11 . In this embodiment, the cap  2  is formed as a U-shape structure capable of covering the opening  11  of the housing  1 , and a part of two outer walls. The cap  2  is latched into two grooves  15  which extend axially on the two side walls of the housing  1  by two side pieces  21 , and locking holes  22  of the two side pieces  21  are locked with wedge-shape locking projections  16  inside the grooves  15 , to assemble with the housing  1  into one body. Although not shown on the drawings, the cap  2  and the housing  1  can be mutually latched by projected strips or grooves, or can be assembled by adhesive agents. 
         [0033]    Upon assembling the aforementioned tilt switch, first of all, three terminals T are inserted into the terminal holes  1   a  at the bottom  12  of the housing  1  to be fixed, or inserted into an injection mold and constituted with the housing  1  into one body when the housing  1  is molded. Next, the ball member  3  is emplaced into the housing  1 , followed by covering the opening  11  of the housing  1  with the cap  2 , thereby accomplishing the assembly of the switch S. 
         [0034]    The switch S is usually installed on the electronic machine M in a horizontal state for use, as shown in  FIG. 4 . Under this state, the switch is at an OFF state, and the ball member  3  is only in touch with the front end of the terminal T 1  (represented by the solid line) or is not in touch with the terminal T 1  (represented by the dotted line) at all, in the housing  1 . However, when the switch S allows an end of the housing  1  to be lifted up as shown in  FIG. 5 , due to that the electronic machine M tilts in counterclockwise direction; the ball member  3  will roll down along the tilted wall. When the switch tilts to exceed the specified operation angle, i.e., the tilt angle θ, the ball member  3  will cross over the front end of the lower terminal T 1  by its weight, to contact the front end of the upper terminal T 2 . As the diameter of the ball member  3  is larger than the diameter of the circumscribed circle of the triangle constituted by the terminals T 1 , T 2 , and the movement of the ball member  3  is restricted by the inner wall of the housing  1 , the ball member  3  will contact the terminals T 1 , T 2 , to form an ON state. 
         [0035]    On the other hand, when the switch restores reversely from the tilt position as shown in  FIG. 5 , to original horizontal state, the ball member  3  will first escape from the terminals T 2  due to its weight, and then cross over the terminal T 1  to fall on a top of the guide member  14 , thereby restoring with the switch to the horizontal state as shown in  FIG. 4 . Therefore, the switch will be at an OFF state. 
         [0036]    The critical angle (the tilt angle θ) of the aforementioned ON/OFF operation is determined by elevation difference α between the terminal T 1  and the terminal T 2  in a specified range. In other words, in the specified range, the larger the elevation difference α is, the smaller the tilt angle θ will be; and the smaller the elevation difference α is, the larger the tilt angle θ will be. Therefore, by adjusting the magnitude of the elevation difference α, the tilt angle θ can be configured at the required degrees. 
         [0037]    To achieve the aforementioned objects, the length of the front end of the terminal T 1  that protrudes out of the bottom  12  of the housing  1  can be freely adjusted. At this time, the terminal T 2  can be configured as a fixed type that is fixed at the bottom  12 . On the contrary, if the terminal T 2  is configured as an adjustable type, then the terminal T 1  can be also configured as the fixed type. Under any aforementioned situation, the protrusion length of the terminal T 2  cannot be longer than that of the terminal T 1 . 
         [0038]    To adjustably install the terminal T 1  or T 2 , an end of the terminal is threaded to screw with an adjustable nut installed on the housing  1  (not shown on the drawings), which belongs to a prior art. All kinds of terminals of different lengths can be prepared, on the other hand, and adequate terminals can be chosen according to requirement of a user, to be installed on the housing  1 , or to be embedded in a molding tool to be formed integrally with the housing  1 . 
         [0039]    Referring to  FIG. 6  and  FIG. 7 , it shows schematic views of a second embodiment of the tilt switch of the present invention. In this embodiment, all of the components that are the same as those of the first embodiment will use the same numerals, and their descriptions are omitted. 
         [0040]    The second embodiment is provided with the same fundamental structures as those of the first embodiment, including still the housing  1 , the cap  1 , the ball member  3 , and three terminals T. The difference is that in the first embodiment, the tilt angle θ for the ON/OFF operation of the switch is determined by the elevation difference α between the terminals, whereas in the second embodiment, in addition to depending upon the elevation difference α, the tilt angle θ can be also determined by a radial gap β between a top surface of the conductive member  14  on the inner wall  13  and the front end of the terminal T 1  that contacts with the ball member  3 . 
         [0041]    The larger the gap β is, the larger the tilt angle θ that the ball member  3  crosses over the front end of the terminal T 1  will be. On the contrary, the smaller the gap β is, the easier the ball member  3  will cross over the front end of the terminal T 1 , and thus the smaller the tilt angle θ will be. Therefore, the magnitude of the gap β can also determine the magnitude of the tilt angle θ. 
         [0042]      FIG. 6  shows a schematic view of a usage state of a switch having a larger gap β1, wherein the tilt angle θ1 for the ON/OFF operation is larger. On the other hand,  FIG. 5  shows a schematic view of a usage state of a switch having a gap β smaller than the aforementioned gap β1, wherein the tilt angle θ is also smaller. 
         [0043]      FIG. 7  shows a schematic view of a usage state of a switch having a gap β2 further smaller than the gap β, wherein the tilt angle θ2 for the ON/OFF operation is even smaller than θ. From  FIG. 7  it can be shown that to reduce the gap β2, an upper part at one end of an inner side of the guide member  14  is cut off to form a stage part which is touched by a lower part of the terminal T 1 . 
         [0044]    To achieve the aforementioned objects, for the terminal T 1  with a fixed installation position, the magnitude of the gap β can be adjusted by increasing or decreasing radial height (thickness) h of the guide member  14 , thereby adjusting the magnitude of the tilt angle θ. The height h of the guide member  14  can be determined according to the tilt angle required by the user. This guide member  14  can be formed integrally with the housing  1 , so as to avoid the assembly of the guide member  14 . If the height h of the guide member  14  needs to be changed, replacing a core of a mold is sufficient. In other embodiments, the guide member  14  is molded separately and then assembled at the inner wall  13  of the housing  1 . 
         [0045]    To assemble the guide member  14  with the housing  1 , a base portion  14   a  of the guide member  14  is pressed into a corresponding axial groove  13   a  on the inner wall  13  for fixing, as shown in  FIG. 8(A) ; or an inverted T-shape base portion  14   b  of the guide member  14  can be engaged into the same shape of groove  13   b  for assembling, as shown in  FIG. 8(B) . However, the assembly means is not limited to the aforementioned embodiment, a conventional assembly or installation device can be used too. If the guide member  14  is constructed as a structure that can be freely installed into or removed from a groove, then there is no need to change the molding tool but to replace with the guide member  14  of different thickness for achieving an advantage of changing the tilt angle θ easily. 
         [0046]    Accordingly, at the ON position of the switch, the electrically conductive ball member is supported by three terminals with the elevation difference, to configure as a triangle, thereby easily achieving a stable mechanics balance by three points. At the same time, the ball member is blocked by the terminal which protrudes longer, to have a tendency to move toward the other two terminals in front of the tilt direction; therefore, the intermittent electric conduction phenomenon can be reduced upon performing the ON/OFF operation at the critical angle, thereby improving the operability of the switch. Furthermore, by adjusting or changing the elevation difference α of the terminals or the height h of the guide member, as well as the gap β, the operation angle (tilt angle θ) of the switch can be adjusted or changed. In addition, the present invention is provided with the simple structures, fewer components, the easy assembly operation, and thus is well equipped with productive potentialities. 
         [0047]    It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.