Abstract:
A stop lamp switch including: an enclosure; a reed switch disposed in the enclosure; a magnet, disposed in the enclosure, a magnetic field of which opens and closes the contacts of the reed switch; an actuating shaft that is movable along an axial direction of the enclosure; a blocking member provided on the actuating shaft, that moves with the movement of the actuating shaft, between a first position, at which the magnetic field from the magnet directed toward the first reed switch is blocked, and a second position, at which the blocking of the magnetic field from the magnet directed toward the first reed switch is no longer blocked.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a stop lamp switch and particularly to a stop lamp switch that opens and closes contacts with movement of an actuating shaft. 
     2. Description of the Related Art 
     Brake lamps are generally provided in vehicles to signal vehicles behind the vehicle that braking is done. These brake lamps are lighted and extinguished by opening and closing contacts provided in a stop lamp switch operated by a brake pedal. 
     In a conventional stop lamp switch, the actuating shaft is linked to and moves in concert with a brake pedal, a case that movably holds the actuating shaft, a fixed contact provided in the case, and a movable contact provided on the actuating shaft that makes connection with the fixed contact with movement of the actuating shaft when the brake pedal is depressed. If dust or oil becomes attached between the fixed contact and the movable contact, it is not possible to establish proper electrical conduction between the contacts. 
     To prevent dust or oil from becoming between the fixed contact and the movable contact Japanese Patent Application Publication No. JP-A-2004-0714512 describes disposing a sealing member between the case and the actuated contacts. The sealing member is formed of an elastic material, such as rubber or elastomer, and is configured to enable displacement accompanying the movement of a sliding member. Because the fixed contact and the movable contact are isolated from the outside by the sealing member, the configuration is one intended to prevent the attachment of dust and oil between the contacts. 
     However, because the sealing member covering the fixed contact and movable contact is made of an elastic material such as rubber and because it deforms with movement of the actuating shaft, if the sealing member deteriorates with the passage of time, the quality of its sealing against dust decreases, so that there is a risk of not providing reliable prevention of dust and the like becoming attached to the contacts. Also, it is possible that the deterioration of the sealing member with the passage of time can bring with it generation of dust from the sealing member, and attachment of the dust to the contacts can impede the proper operation of the contacts. 
     SUMMARY OF THE INVENTION 
     The present invention provides a stop lamp switch that is not easily susceptible to deterioration with the passage of time and that can provide proper contact operation. 
     Aspects of the present invention have the following means. 
     A first aspect of the present invention is a stop lamp switch having an enclosure; a reed switch disposed in the enclosure; a magnet disposed in the enclosure that generates a magnetic field for the purpose of opening and closing the contacts of the reed switch; an actuating shaft that is movable along one axis direction of the enclosure; and a blocking member provided on the actuating shaft that moves with the movement of the actuating shaft, between a first position, at which the magnetic field from the magnet directed toward the reed switch is blocked, and a second position, at which the magnetic field from the magnet directed toward the reed switch is not blocked. 
     A second aspect of the present invention is similar to the first aspect, except that the magnet is disposed to the outside relative to the blocking member, and the reed switch is disposed to the inside relative to the blocking member. 
     A third aspect of the present invention is similar to the first aspect, except that the magnet is disposed to the inside relative to the blocking member, and the reed switch is disposed to the outside relative to the blocking member. 
     A fourth aspect of the present invention is similar to the first to third aspects, except that multiple reed switches are provided at locations to which the magnetic field of the magnet reaches. 
     A fifth aspect of the present invention is similar to the first to fourth aspects, except that an aperture is formed in the blocking member and, when the blocking member is positioned at the second position, the aperture is opposite the contacts of the reed switch. 
     A sixth aspect of the present invention is similar to the first or second aspect, except that the actuating shaft covers the reed switch. 
     A seventh aspect of the present invention has an enclosure, a reed switch disposed within the enclosure, an actuating shaft that is movable along one axial direction of the enclosure, and a magnet that generates a magnetic field for the purpose of opening and closing the contacts of the reed switch and that moves with the movement of the actuating shaft, between a first position, at which a magnetic field is not applied to the reed switch, and a second position, at which the magnetic field is applied to the reed switch. 
     An eighth aspect of the present invention is similar to the seventh aspect, except that multiple reed switches are provided at locations to which the magnetic field of the magnet reaches 
     A ninth aspect of the present invention is similar to the seventh or eighth aspect, except that the actuating shaft covers the reed switch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and further objects, features, and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein: 
         FIG. 1A  and  FIG. 1B  are drawings that depict the basic configuration of a stop lamp switch according to an embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of a stop lamp switch according to a first embodiment of the present invention; 
         FIG. 3  is a perspective view showing the assembled condition of a stop lamp switch according to the first embodiment of the present invention; 
         FIG. 4  is a side view of the reed switch and the terminals; 
         FIG. 5  is a perspective view of the reed switch and the terminals; 
         FIG. 6A  to  FIG. 6C  are drawings that depict the operation of a stop lamp switch according to the first embodiment of the present invention; 
         FIG. 7A  and  FIG. 7B  are cross-sectional views of the configuration and operation of a stop lamp switch according to a second embodiment of the present invention; 
         FIG. 8A  to  FIG. 8C  show in enlarged form the region of the case of a stop lamp switch according to a third embodiment of the present invention; 
         FIG. 9  shows in enlarged form the case of a stop lamp switch according to the third aspect of the present invention with the blocking member removed; 
         FIG. 10  is a perspective view, shown in enlarged form, of the region of the case of a stop lamp switch according to a fourth embodiment of the present invention; 
         FIG. 11A  and  FIG. 11B  are perspective views showing the blocking member provided in a stop lamp switch according to the fourth embodiment of the present invention; 
         FIG. 12  is a perspective view showing in enlarged form the case of a stop lamp switch according to the fourth aspect of the present invention with the blocking member removed; 
         FIG. 13A  and  FIG. 13B  are cross-sectional views of the configuration and operation of a stop lamp switch according to a fifth embodiment of the present invention; 
         FIG. 14A  and  FIG. 14B  are cross-sectional views of the configuration and operation of a variation of the stop lamp switch according to the fifth embodiment of the present invention; 
         FIG. 15  is an exploded perspective view of the variation of the stop lamp switch according to the fifth embodiment of the present invention; 
         FIG. 16A  shows a rear perspective view of the stop lamp switch according to a variation of the fifth embodiment of the present invention; and 
         FIG. 16B  is a cross-sectional view of the configuration and operation of a variation of the stop lamp switch according to the fifth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Specific forms that embody the present invention are described below, with references made to the accompanying drawings. 
       FIG. 1A  and  FIG. 1B  are drawings depicting the principle of a stop lamp switch according to an embodiment of the present invention.  FIG. 1A  shows the condition of a stop lamp switch  10 A when the brake pedal is not depressed (pedal non-operated condition) and  FIG. 1B  shows the condition of the stop lamp switch  10 A when the brake pedal is depressed (pedal operated condition). 
     The stop lamp switch  10 A generally has a case (enclosure)  11 , a housing  12 , an actuating shaft  13 , a reed switch  14 , a magnet  15 , and a blocking member  16  and the like. The stop lamp switch  10 A is disposed to make contact with the brake pedal, and the actuating shaft  13  follows the movement of the brake pedal as the brake pedal is depressed and released, thereby switching the reed switch  14  on and off to light and extinguish a stop lamp. 
     An internal space is formed by combining the case  11  and the housing  12 . The reed switch  14  and connector terminals  19  are disposed in the case  11 , and the actuating shaft  13  and the magnet  15  are disposed in the housing  12 . 
     The reed switch  14  has reeds  21  and  22  inside a glass tube  23 . Part of each reed  21  and  22  extends to outside the glass tube  23  and is connected to a connector terminal  19 . The connector terminals  19  are connected to stop lamp drive circuit (not illustrated) that causes the stop lamp to light up. 
     The actuating shaft  13  is movably mounted in the housing  12  in the direction indicated by the arrows X 1  and X 2  in drawing. A housing space  18  opening in the X 1  direction is provided in the actuating shaft  13 . The reed switch  14  is positioned within the housing space  18 . The size of the housing space  18  is established so that even if the actuating shaft  13  moves in the X 1  and X 2  directions accompanying movement of the brake pedal, there is no influence on the reed switch  14 . The actuating shaft  13  is constantly impelled in the direction of arrow X 2  by a spring  17 . 
     The magnet  15  is disposed in the housing  12  to sandwich the reed switch  14  with N and S poles in opposition. Therefore, when the blocking member  16  is not present between the reed switch  14  and the magnet  15 , the magnetic field generated by the magnet  15  acts on the reeds  21  and  22  within the glass tube  23 , so that the reeds  21  and  22  make contact and go into the conducting condition. 
     The blocking member  16  is a cylindrical member made of a magnetic material capable of blocking a magnetic field, and is disposed on the actuating shaft  13 . Thus, the blocking member  16  moves in the X 1  and X 2  directions with the movement of the actuating shaft  13 . 
     When the brake pedal is not operated, the actuating shaft  13  shown in  FIG. 1A  moves in the direction of the arrow X 1  and the blocking member  16  moves to a position between the reed switch  14  and the magnet  15  (first position). Thus, the blocking member  16  blocks the magnetic field of the magnet  15  so that the magnetic field does not act on the reed switch  14 . For this reason, the reed switch  14  is in the off (open) condition, and the stop lamp is in the extinguished condition. 
     In contrast, when the brake pedal is operated, the actuating shaft  13  moves in the direction of the arrow X 2  by the force of the spring  13 , which also moves the blocking member  16  in the X 2  direction. For this reason, as shown in  FIG. 1B , the blocking member  16  moves away from between the reed switch  14  and the magnet  15 , and to a position that allows the reed switch  14  and the magnet  15  to come into direct opposition (second position). The magnetic field of the magnet  15  therefore acts on the reed switch  14  and the reed switch  14  goes into the on (closed) condition. For this reason, the stop lamp is lighted via the stop lamp drive circuit connected to the connector terminals  19 . 
     The stop lamp switch  10 A according to the foregoing embodiment uses a reed switch as the contacts, so that other members do not come into contact with the reeds  21  and  22 , the on/off operation of the contacts being made in a non-contacting manner. The contacts of the reeds  21  and  22  are sealed within the glass tube  23 . 
     For this reason, in the stop lamp switch  10 A according to this embodiment, unlike conventional switches, there are no moving parts at the sealed part protecting the contacts so that no damage occurs to the sealed part. Also, because the reed switch  14  contacts are disposed within the glass tube  23 , the interior of which is either a vacuum or filled with an inert gas, impurities do not enter the glass tube  23 . It is therefore possible to achieve a stop lamp switch  10 A having improved reliability and long life. 
     By providing a housing space  18  in the actuating shaft  13  and adopting a configuration in which the reed switch  14  is inserted into the a housing space  18 , it is possible to reduce the length of the stop lamp switch  10 A in the direction of arrows X 1  and X 2  than a configuration in which the reed switch  14  is not inserted. 
     Specifically, it is possible to shorten the stop lamp switch  10 A by the distance the reed switch  14  is inserted into the actuating shaft  13 . By doing this, it is possible to improve the ease of mounting to the brake pedal installation location, which is generally in cramped quarters. Also, the operating effect of the stop lamp switch  10 A shown in  FIG. 1A  and  FIG. 1B  can be achieved by the stop lamp switches  10 B to  10 F according to embodiments of the present invention to be described below. 
     Stop lamp switches  10 B to  10 F according to embodiments of the present invention and based on the above-described principle will now be described.  FIG. 2  to  FIG. 13B  show stop lamp switches  10 B to  10 F according to the first to fifth embodiments of the present invention. In  FIG. 2  to  FIG. 13B , the same or corresponding elements as in  FIG. 1A  and  FIG. 1B  are assigned the same reference numerals and will not be repeated described herein. 
     The stop lamp switch  10 B according to the first embodiment of the present invention will first be described, with reference made to  FIG. 2  to  FIG. 6C . As shown in  FIG. 2 , a pair of connector terminals  19  is inserted into and integrally with the case  11  (these being shown separated from the case  11  in the drawings). The reed switch  14  is connected to the pair of connector terminals  19 .  FIG. 4  and  FIG. 5  show enlarged views of the reed switch  14 . In this embodiment, the reed switch  14  is mounted on a terminal  20 . 
     The terminal  20  is made of an electrically conductive material, and is integrally formed with a holding member  20   a , a terminal part  20   b , and a connecting part  20   c . The holding member  20   a  sandwiches the glass tube  23  to hold the reed switch  14 . 
     When this is done, the position of the holding member  20   a  is established at a position that is offset from the contacts disposed inside the glass tube  23 . By doing this, it is possible to apply the magnetic field of the magnet  15  to the contacts (reeds  21  and  22 ) inside the glass tube  23 , without being hindered by the terminal  20 . 
     The connecting part  20   c , which extends outside of the glass tube  23  in the direction of arrow X 2 , is connected to the reed  22  of the reed switch  14 . The terminal part  20   b  is bent into an L-shape and is electrically connected to the connector terminals  19 . The reed  21  of the reed switch  14  that extends in the X 1  direction is also bent into an L-shape and electrically connected to a connector terminal  19 . 
     The magnet  15  is substantially ring shaped, and is fixed to the housing  12  by pressing it into the housing  12 . The magnet  15  is disposed at outside of the reed switch  14 . The blocking member  16  is cylindrically shaped and is pressed into the actuating shaft  13 . A housing space  18  is formed in the actuating shaft  13  and the terminal  20  (including the reed switch  14 ) may be inserted into the housing space  18 . 
     In the stop lamp switch  10 B, because the connector terminals  19  are formed so as to be inserted into the case  11 , the reed switch  14  is held by the terminal  20 , the magnet  15  is fixed to the housing  12  by pressing thereinto, and the blocking member  16  is pressed into the actuating shaft  13 , it is possible to facilitate assembly. Also, as shown in  FIG. 3 , the assembled stop lamp switch  10 B is compact, making it easy to mount to the brake pedal installation location. 
       FIG. 6A  to  FIG. 6C  depict the operation of the stop lamp switch  10 B.  FIG. 6A  shows the stop lamp switch  10 B when the brake pedal is not operated. The actuating shaft  13 , in opposition to the force of the spring  17 , is moved in the direction of the arrow X 1  in the drawing by the brake pedal, and in this condition the blocking member  16  provided in the actuating shaft  13  is positioned between the magnet  15  and the reed switch  14 . 
     For this reason, the blocking member  16  blocks the magnetic field of the magnet  15 , so that the magnetic field does not act on the reed switch  14 . The reed switch  14  therefore goes into the off (open) condition, and the stop lamp is in the extinguished condition. In this condition, the reed switch  14  is inserted the most deeply into the housing space  18 . 
       FIG. 6B  shows the condition in which the brake pedal starts to be depressed, whereby the actuating shaft  13  moves in the direction of the arrow X 2  by the force of the spring  17  to the position at which the contacts are switched. The contact switching position is the limiting position at which the blocking member  16  can block the magnetic field generated by the magnet  15 . If the pedal is depressed further from this condition, the actuating shaft  13  moves beyond the contact switching position in the direction of the arrow X 2 . 
     As shown in  FIG. 6C , when the brake pedal is depressed the actuating shaft  13  is moved in the direction of the arrow X 2 . In this condition, the blocking member  16  is removed from the position between the reed switch  14  and the magnet  15 , so that the reed switch  14  and the magnet  15  are in direct opposition. Thus, the magnetic field of the magnet  15  (indicated by the downward-pointing arrow in the drawing) acts on the reed switch  14 , and the stop lamp is lighted via the stop lamp drive circuit connected to the connector terminals  19 . 
     The stop lamp switch  10 C according to the second embodiment of the present invention will now be described. 
       FIG. 7A  and  FIG. 7B  show the stop lamp switch  10 C according the second embodiment of the present invention. A feature of the stop lamp switch  10 C of the second embodiment is that it has two reed switches  14  and  25 , two blocking members  16 A and  16 B, and two magnets  15 A and  15 B. The reed switch  14  is used to turn the brake lamp on and off, as in the case of the first embodiment. 
     The reed switch  25 , in contrast, functions as a brake switch that detects the operation of the brake pedal. As described later, the reed switch  25  is on (closed)when the brake pedal is not depressed, and off (open) when the brake pedal is depressed. 
     The reed switch  25  is connected to the connector terminals  26 , and the connector terminals  26  are connected, for example, to an engine control unit (ECU). The ECU detects the depression of the brake pedal by a brake signal sent from the reed switch  25 . In this embodiment the reed switch  25  is mounted on the case  11  in a direction perpendicular to the plane of the drawing, in order to prevent an increase in size in the directions of the arrows X 1  and X 2 . 
     The first magnet  15 A is formed substantially the same as the magnet  15  of the stop lamp switch  10 B in the first embodiment. That is, the first magnet  15 A is disposed in the housing  12  opposite the reed switch  14 . In contrast, the second magnet  15 B is fixed to the case  11  opposite the reed switch  25 . The position of the second magnet  15 B is established so that it is possible for the magnetic field of the second magnet  15 B to act on the reed switch  25 . 
     The first blocking member  16 A is formed substantially the same as the blocking member  16  of the stop lamp switch  10 C of the first embodiment. That is, the first blocking member  16 A is fixed to the actuating shaft  13 , and when the brake pedal is not operated, the actuating shaft  13  is moved in the X 1  direction, (shown in  FIG. 7A ), and the actuating shaft  13  blocks the magnetic field of the magnet  15 , thereby preventing the magnetic field from acting on the reed switch  14 . When the brake pedal is depressed (shown in  FIG. 7B ), the actuating shaft  13  is moved in the X 2  direction, and the first blocking member  16 A moves away from between the first magnet  15 A and the reed switch  14 , thereby allowing the magnetic field of the magnet  15  to act on the reed switch  14 . 
     In contrast to the above, the second blocking member  16 B is made of a magnetic material that can block a magnetic field, and has a cylindrical part  30  and a flanged part  31 . The second blocking member  16 B may also be fixed to the actuating shaft  13 , at a position that is farther in the X 1  direction from the position where the first blocking member  16 A is fixed. 
     An aperture  27  is formed at a prescribed position on the second blocking member  16 B. The aperture  27  is formed so that, when the brake pedal is not depressed the actuating shaft  13  is moved in the X 1  direction (shown in  FIG. 7A ), and the reed switch  25  and the second magnet  15 B are in opposition. Therefore, when the brake pedal is not depressed the magnetic field of the second magnet  15 B acts on the reed switch  25 , so that the reed switch  25  is on. 
     In contrast, when the brake pedal is depressed, the actuating shaft  13  is moved in the X 2  position (shown in  FIG. 7B ), and the second blocking member  16 B is positioned between the reed switch  25  and the second magnet  15 B; thus, blocking the magnetic field of the second magnet  15 B and preventing the magnetic field from acting on the reed switch  25 . In the pedal operated condition, therefore, the magnetic field of the second magnet  15 B does not act on the reed switch  25 , and the reed switch  25  is off. 
     According to the stop lamp switch  10 C of the second embodiment, it is possible to extract two signals from the reed switches  14 ,  15  simultaneously. For this reason, it is possible to obtain two signal from a single stop lamp switch  10 C. Also, by appropriately selecting the position of the aperture  27  in the second blocking member  16 B, it is possible to have the reed switch  25  be in the on condition either in the pedal operated condition or the pedal non-operated condition, thereby increasing the degree of freedom in the setting of the stop lamp switch  10 C. 
     The third embodiment of the present invention will now be described. 
       FIG. 8A  to  FIG. 9  show the stop lamp switch  10 D according to the third embodiment of the present invention.  FIG. 8A  to  FIG. 9  show in enlarged only the characteristic region of the case  11  of the stop lamp switch  10 D, and descriptions of the housing  12  and description of the actuating shaft  13  will be omitted herein. 
     The case of the third embodiment is similar to that of the second embodiment, and has two reed switches  14 ,  25 . The reed switches  14 ,  25 , as shown in  FIG. 9 , are disposed in a parallel row in the case  11 . 
     In this embodiment, one blocking member  16  is provided for both reed switches  14 ,  25 . The magnet  15  has the form of a flat plate, and this magnet  15  is also provided in common for the reed switches  14 ,  25 . 
     The blocking member  16  is moveable in the directions of the arrows X 1  and X 2  in the drawing, by means of the actuating shaft  13  (not illustrated). The side edges of the blocking member  16  are bent inward, as shown in  FIG. 8C , the bent parts thereof are engaged with the case  11  to enable sliding in the guide grooves  28  formed in the case  11  and that extend in the X 1  and X 2  directions. The blocking member  16  can move in the directions of the arrows X 1  and X 2  relative to reed switches  14 ,  25  with the movement of the actuating shaft  13 . 
     Apertures  27 A and  27 B are formed in the blocking member  16 . The aperture  27 A is formed to as to oppose the reed switch  14 , and the aperture  27 B is formed so as to oppose the reed switch  25 . Specifically, when the brake pedal is not depressed (shown in  FIG. 8A ), the blocking member  16  (actuating shaft  13 ) is moved in the direction of the arrow X 1 , the aperture  27 A moves away from the contact position of the reed switch  14 , and the aperture  27 B moves to a position opposite the contacts of the reed switch  25 . 
     When the brake pedal is depressed, the blocking member  16  is moved in the direction of the arrow X 2 , and the aperture  27 A is set at a position opposite the contacts of the reed switch  14  and the aperture  27 B is set at a position that is removed from the position of the contacts of the reed switch  25 . The magnetic field of the magnet  15  selectively act on the reed switch  14  and the reed switch  25 . 
     In the stop lamp switch  10 D having the above-noted configuration, when the brake pedal is not depressed the magnetic field of the magnet  15  acts on the reed switch  25  via the aperture  27 B, so that the reed switch  25  is in the on (closed) condition. In contrast, the reed switch  14  is off (open) because the blocking member  16  blocks the magnetic field of the magnet  15 . 
     On the other hand, when the brake pedal is depressed, the magnetic field of the magnet  15  acts on the reed switch  14  via the aperture  27 A, so that the reed switch  14  is in the on (closed) condition. In contrast, the reed switch  25  is in the off (open) condition because the blocking member  16  blocks magnetic field of the magnet  15 . 
     In the stop lamp switch  10 D of the above-noted third embodiment of the present invention as well, it is possible obtain two signals simultaneously from the two reed switches  14 ,  25 . Also, by appropriately selecting the position of the apertures  27 A,  27 B, it is possible to increase the degree of freedom in the setting of the stop lamp switch  10 D. Additionally, because only one magnet  15  is required, there is a reduction in the number of parts in comparison with the stop lamp switch  10 C of the second embodiment. 
     The fourth embodiment of the present invention will now be described. 
       FIG. 10  to  FIG. 12  are drawings for describing the stop lamp switch  10 E according to the fourth embodiment of the present invention.  FIG. 10  shows in enlarged the region of the case  11  of the stop lamp switch  10 E, and the description of the housing  12  is omitted herein. 
     The stop lamp switch  10 E of this embodiment, in addition to having the magnet  15  disposed to the inside of the blocking member  16 , has the reed switches  14 ,  25  disposed the outside of the blocking member  16 .  FIG. 12  is an enlarged view of the region of the magnet  15  of the stop lamp switch  10 E. As shown in this drawing, a single magnet  15  is disposed in the case  11 , within the blocking member  16 . 
     The blocking member  16 , as shown in enlarged form in  FIG. 11A  and  FIG. 11B , has a U-shaped profile, and is movable in the directions of the arrows X 1  and X 2 , guided by the guide grooves  28  formed in the case  11 . Because the blocking member  16  is fixed to the bottom end of the actuating shaft  13 , blocking member  16  moves in the X 1  and X 2  directions with the movement of the actuating shaft  13  in the X 1  and X 2  directions. 
     Apertures  27 A,  27 B are formed in the blocking member  16  (refer to  FIG. 11A ). The positions at which the apertures  27 A,  27 B are formed so as to be equivalent to the positions of the apertures  27 A,  27 B described in the third embodiment. 
     In the stop lamp switch  10 E, therefore, when the brake pedal is not depressed the magnetic field of the magnet  15  acts on the reed switch  25  via the aperture  27 B, so that the reed switch  25  is in the on (closed) condition. In contrast, the reed switch  14  is in the off (open) condition, because the blocking member  16  blocks the magnetic field of the magnet  15 . 
     On the other hand, when the brake pedal is depressed the magnetic field of the magnet  15  acts on the reed switch  14  via the aperture  27 A, so that the reed switch  14  is in the on (closed) condition, while the reed switch  25  is in the off (open) condition because the blocking member  16  blocks the magnetic field of the magnet  15 . 
     In this embodiment, by disposing the magnet  15  on the inside of the blocking member  16 , it is possible with a compact magnet  15  to apply a magnetic field to the plurality of reed switches  14 ,  25 , thereby enabling an improvement in the compactness of the stop lamp switch  10 E. Also, because of the two reed switches  14 ,  25 , it is possible to achieve the same type of effect as the second and third embodiments. 
     The fifth embodiment of the present invention will now be described. 
       FIG. 13A  and  FIG. 13B  show a stop lamp switch  10 F according to the fifth embodiment of the present invention. While the foregoing described embodiments had blocking members  16 ,  16 A, and  16 B, this embodiment adopts a configuration in which the reed switches  14  and  25  contacts are switched on and off without using the blocking members  16 ,  16 A, and  16 B. 
     In this embodiment, the magnet  15  is provided on a flange part  32  formed on the end part of the actuating shaft  13  in the X 1  direction. Therefore, the magnet  15  moves in the X 1  and X 2  directions with the movement of the actuating shaft  13  in the X 1  and X 2  directions. Also, the reed switch  25  is disposed in the case  11 , similar to the other embodiment, but is disposed at a position that is opposite the magnet  15  (in the X 1  and X 2  direction). 
     When the brake pedal is not depressed, therefore, the actuating shaft  13  is moved in the X 1  direction, as shown in  FIG. 13A , and the magnet  15  approaches the reed switch  25 , so that the magnetic field of the magnet  15  acts on the reed switch  25 , causing it to be in the on (closed) condition. In contrast, when the brake pedal is depressed, the actuating shaft  13  is moved in the X 2  direction, as shown in  FIG. 13B , and the magnet  15  moves away from the reed switch  25 , so that the magnetic field of the magnet  15  does not act on the reed switch  25 , causing the reed switch  25  to be in the off (open) condition. 
     The reed switch  14  is configured so that it can be inserted into the housing space  18  formed in the actuating shaft  13 . The magnet  15  is provided on the end part in the X 1  direction of the actuating shaft  13 . When the brake pedal is not depressed, therefore, as shown in  FIG. 13A , most of the reed switch  14  is inside the housing space  18 , and the magnetic field of the magnet  15  does not act on the contacts of the reed switch  14 . The reed switch  14 , therefore, is in the off (open) condition when the brake pedal is not depressed. 
     In contrast to this, when the actuating shaft  13  is moved in the X 2  direction by the depressing of the brake pedal, the magnet  15  also moves in concert in the X 2  direction. By moving the actuating shaft  13  in the X 2  direction, the reed switch  14  that is fixed to the case  11  moves out of the housing space  18  so as to be exposed. 
     When the brake pedal is depressed, as shown in  FIG. 13B , the magnet  15  is opposite the reed switch  14  (when considered in the Y 1 , Y 2  direction). Therefore, when the brake pedal is depressed, the reed switch  14  is closed. 
     As noted above, the stop lamp switch  10 F of this embodiment is able to switch the reed switches  14 ,  25  on and off by a single magnet  15 , without using blocking members. It is therefore possible to reduce the number of parts compared to the other embodiments, to facilitate assembly, and to achieve compactness. 
     A variation of the embodiment of the present invention will now be described. 
       FIG. 14  to  FIG. 15  show a stop lamp switch  10 G according to a variation of the fifth embodiment of the present invention. The stop lamp switch  10 G of this variation is similar to the stop lamp switch  10 F of the fifth embodiment, switches the contacts of the reed switches  14 ,  25  on and off without using a blocking member. 
     The stop lamp switch  10 G of this variation, however, differs from the stop lamp switch  10 F of the fifth embodiment in that it uses a ring-shaped magnet as the magnet  15 , and in that the reed switch  25  extends in the movement direction of the actuating shaft  13  (X 1  and X 2  directions). 
     By disposing the reed switch  25  to extend in the X 1  and X 2  directions as in this embodiment, the reed switch  14  and the reed switch  25  are substantially parallel. The contact position of the reed switch  14  and the contact position of the reed switch  25  are offset in the X 1  and X 2  directions. Specifically, the contact position of the reed switch  14  (position at which the magnetic field switches the switch on and off) is offset by a prescribed amount in the X 2  direction from the contact position of the reed switch  25 . 
     In this variation as noted above, a ring-shaped magnet  15  is used, and the reed switch  14  is disposed to the inside of this ring-shaped magnet  15 , with the reed switch  25  disposed to the outside of the ring-shaped magnet  15 . Because the ring-shaped magnet  15  is mounted to the actuating shaft  13 , and the reed switches  14 ,  25  are fixed to the case  11 , by the actuating shaft  13  moving in the X 1  and X 2  directions, the magnet  15  moves in the X 1  and X 2  directions relative to the reed switches  14 ,  25 . 
     When the brake pedal is not operating, the actuating shaft  13  is moved in the X 1  direction, as shown in  FIG. 14A , and the ring-shaped magnet  15  approaches the contacts of the reed switch  25 . The result is that the magnetic field of the ring-shaped magnet  15  acts on the contacts of the reed switch  25 , so that the reed switch  25  goes into the on (closed) condition. When this occurs, because the contacts of the reed switch  14  are offset from the contacts of the reed switch  25 , the magnetic field of the ring-shaped magnet  15  does not act on the contacts of the reed switch  14 , so that the reed switch  14  is in the off (open) condition. 
     On the other hand, when the brake pedal is operated, the actuating shaft  13  is moved in the X 2  direction, as shown in  FIG. 14B , the ring-shaped magnet  15  approaches the contacts of the reed switch  14 . The result is that the magnetic field of the ring-shaped magnet  15  acts on the contacts of the reed switch  14 , so that the reed switch  14  is closed. When this occurs, because the contacts of the reed switch  25  are offset from the contacts of the reed switch  14 , the magnetic field of the ring-shaped magnet  15  does not act on the contacts of the reed switch  25 , so that the reed switch  25  is in the off (open) condition. 
     As noted above, the stop lamp switch  10 G of this variation, similar to the stop lamp switch  10 F of the fifth embodiment, may switch two reed switches  14 ,  25  on and off with a single magnet, without using a blocking member. It is therefore possible to reduce the number of parts compared to the other embodiments, to facilitate assembly, and to achieve compactness. 
     In this variation, because the magnet  15  is ring-shaped and the reed switch  14  is disposed inside the ring-shaped magnet  15  and the reed switch  25  is disposed outside the ring-shaped magnet  15 , it is possible to use a compact magnet  15  to have a magnetic field act on each of the reed switches  14 ,  25 , thereby making it possible to achieve compactness in the stop lamp switch  10 G, while achieving reliable switching operation. 
     The on/off timing of the reed switch  14  accompanying movement of the actuating shaft  13  and the on/off timing of the reed switch  25  accompanying movement of the actuating shaft  13  may be varied by adjusting the contact positions of the reed switch  14  and the reed switch  25  within the case  11  and the housing  12 . In particular, if the reed switch  14  and the reed switch  25  are disposed in parallel, it is possible to perform this adjustment for each of the reed switch  14  and the reed switch  25 . 
     In this variation as well, the reed switch  14  is inserted inside the actuating shaft  13 . For this reason, it is possible to set the contact position of the reed switch  14  without regard to the movement region of the actuating shaft  13 , and therefore possible to increase the degree of freedom of setting the on/off timing of the reed switches  14 ,  25 . 
     A variation of the embodiment of the present invention will now be described. 
       FIG. 16A and 16B  show a stop lamp switch  10 H according to a variation of the fifth embodiment of the present invention. The stop lamp switch  10 H is similar to the stop lamp switch  10 G. However, stop lamp switch  10 H shows two reed switches  14 A and  14 B disposed to the inside of the ring-shaped magnet  15 , with the reed switch  25  disposed to the outside of the ring-shaped magnet  15 . The contacts of the reed switch  25  are offset from the contacts of reed switches  14 A and  14 B. 
     Although each of the foregoing examples show the use of one or two reed switches, any number of reed switches may be used as appropriate. 
     According to the present invention, by using a reed switch and operating the contacts in a non-contacting manner, it is possible to eliminate moving parts in a sealing part and prevent damage to the sealing part. Because the contacts of the reed switch are disposed in a glass tube, the interior of which is either a vacuum or filled with an inert gas, there is no intrusion of impurities into the glass tube.