Abstract:
An electrical switch for low to medium wattage applications such as in vehicles, appliances, and the like, includes a flexible, resilient spring member which is operable mechanically to latch the switch in one of two positions while also carrying electrical current to complete an electrical circuit when the switch is closed in one of the two latched positions. The switch may operate in either single pole, single throw or single pole, double throw configuration, and provides at least one audible sound or click in each of its latched positions to indicate its status, and also may include a visual indication of status. Preferably, a conductive, metallic, coil spring is carried by a non-conductive switch actuator, the spring having a contact member that is moved between latched positions by finger pressure of an operator on the actuator to open and close one or more electrical circuits connected to the switch contacts.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority from U.S. Provisional Patent Application Ser. No. 60/396,844, filed Jul. 18, 2002, entitled DPDT PUSH/PUSH LATCHING ELECTRICAL SWITCH, invented by Edward Roger Adams. 

   FIELD OF THE INVENTION 
   This invention relates to electrical switches, especially of the type for use with accessories and other controls in vehicles, appliances, and other applications and, more particularly, to a latching-type, push/push, single pole, single or double throw electrical switches. 
   BACKGROUND OF THE INVENTION 
   A wide variety of electrical accessories and controls used in vehicles are operated with electrical switches. As one example, interior rearview mirror assemblies in vehicles now often incorporate map or reading lights or other accessories which are controlled by electrical switches. Typically, such switches operate by pushing an actuator or button causing the switch to move from a first position in which the light or other accessory is operated to a second position in which the light or other accessory is turned off. Various types of switches are useful in such assemblies including rocker-type or push/push switches. For example, U.S. Pat. No. 4,807,096 to Skogler et al. and U.S. Pat. No. 5,649,756 to Adams et al. disclose interior rearview mirror assemblies that each incorporate a pair of rocker type, single pole, double thrown switches for operating lights within the mirror assembly. More recently, push/push type electrical switches have been incorporated in rearview mirror assemblies as shown in U.S. Pat. No. 5,669,698 to Veldman et al., U.S. Pat. No. 5,820,245 to Desmond et al., U.S. Pat. No. 6,386,742 to DeLine et al., and European Patent Application No. 615882 A2. The switches shown in DeLine et al. U.S. Pat. No. 6,386,742 include actuating plungers extending downwardly through apertures in the rearview mirror housing. The plungers are adapted to be depressed to operate the switches and to extend farther outwardly away from the mirror assembly when the switch is in the “on” position. 
   While many prior known switches have operated adequately to control such vehicle accessories, each is a relatively expensive collection of numerous small parts which are difficult to assemble, are often misassembled and, consequently, fail to operate as desired. Because of the number of small pieces involved, the cost of each switch is relatively large. In addition to the cost and reliability issues for the switches themselves, the prior switches have been difficult and time consuming to assemble to the electrical circuits used in rearview mirrors, thereby adding to the overall cost of the assembly. 
   It was, therefore, desired to obtain an electrical switch useful in low to medium voltage/current/wattage applications such as in a vehicle for vehicle accessories and controls, or in a household appliance to control relays which control household current to electric motors or the like, which has fewer operational parts, is more reliable, has a longer lifespan than currently available switches, and is less expensive to manufacture and use. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention provides an electrical switch especially adapted for use in applications such as vehicle accessories and controls, household appliances, and other applications which incorporates a significantly lower number of operational parts than prior known switches, is reliable yet cost efficient in both manufacture and use, and operates as a push/push, latching-type switch that is useful in a large number of applications, and especially low to medium current/voltage applications. In addition, the invention provides both visual and audible indications of switch status and operation. 
   In one form, the invention is an electrical switch for vehicles, appliances, and the like, comprising a first electrical switch contact at a first position, an electrically conductive, resilient spring member having a first portion engaged with the first electrical switch contact and a second portion movable between second and third positions, the second and third positions being spaced from one another and from the first position. A second electrical switch contact is at one of the second and third positions. When the first and second electrical switch contacts are connected to an electrical circuit, movement of the second portion of the spring member between the second and third positions engages and disengages the second spring portion with the second electrical switch contact to thereby open the electrical circuit or close the electrical circuit allowing current to pass through the spring member. 
   In other aspects, the invention includes a contact directing member positioned between the second and third positions, the contact directing member including a cam surface that directs the second portion of the spring member between the second and third positions for engagement as disengagement with the second electrical switch contact. The switch may also include a second contact directing member between the second and third positions, the second contact directing member including a second cam surface that directs the second portion of the spring member from the third to the second position. 
   In yet other aspects of the invention, the spring may be either a flat spring with the second portion of the spring member extending at a right angle to the first portion of the spring member, or a coil spring having a coil with two ends, an axis for the coil, a first arm at one end of the coil extending outwardly away from the coil axis, and a second arm at the other end of the coil also extending outwardly away from the coil axis. The first arm is the first portion of the spring member and the second arm is second portion of the spring member. 
   In one preferred form of the invention, the switch includes a non-electrically conductive switch actuator movable between at least two positions, the spring being mounted on and movable with the actuator. In one form, the switch actuator is movable linearly along a first direction while the cam surface directs the second portion of the spring member in a second direction laterally of the first direction. The second cam surface directs the second portion of the spring member in a third direction different from the first and second directions. The switch actuator may be mounted on switch support which, in preferred versions of the invention, may comprise a molded circuit support which includes insert molded circuit members or bus bars, lamps or bulb holders, or other accessories. The first and second electrical switch contacts are on the switch support in this embodiment. 
   In other aspects of the invention, the resiliency of the spring member urges the switch actuator toward one of two latched actuator positions when the second spring portion is in the second and third positions. In addition, when the second portion of the spring member engages the second electrical switch contact, an audible sound is produced giving an indication of switch operation. Likewise, another audible sound is produced when the second spring portion is moved from the second electrical switch contact to the first electrical switch contact. Preferably, the spring member is mounted on a post on the non-electrically conductive switch actuator and, when the spring is a coil spring, it has an extending arm engaging the first electrical switch contact formed on the switch support while the second portion of the coil spring is movable in at least two dimensions between first and second stop members, at least one of which is the second electrical switch contact when a force is applied to move the switch actuator. When only one of the stop members is electrically conductive and connected to the electrical circuit, the switch functions as a single pole, single throw switch. When both stop members are electrically conductive and connected to the electrical circuit, the switch functions as a single pole, double throw switch. 
   Accordingly, the present invention provides a reliable, low cost electrical switch especially useful for use low to medium current, voltage and wattage applications such as in vehicles, appliances, and the like. The switch combines a mechanical action, preferably a push/push action, with electrical conductivity, and may be configured to operate either as a single pole, single throw or single pole, double throw switch. Preferably, the switch is operated by a spring member which doubles as an electrical current conductor. The mechanical action of the spring is combined with the engagement or disengagement of a portion of the spring with electrical switch contacts to open and close the desired electrical circuit wherein electricity is allowed to flow through or is stopped from flowing through the spring itself. 
   The present invention provides numerous benefits and advantages over prior known switches. Various types of electrically conductive springs may be used in the switch such as round wire, coil springs, flat wire springs, and the like. An operational force can be directly applied to the spring conductor itself since the current conveyed is at only a low to medium voltage thereby avoiding injury to an operator. Alternately, an operational force can be applied via a non-conductive switch actuator on which the current conducting spring is mounted. Portions of the conductive spring can move in two or three dimensions, such movement being combined with the resilience of the spring to enable the production of audible sounds or clicks when the switch moves from one position to another to indicate switch operation. The switch may be incorporated directly on lead frames or circuit members thereby avoiding time consuming, difficult assembly operations. Moreover, the switch can be adapted to be in its on position with the switch actuator or button/plunger either depressed or extended thereby also indicating its status visually. Also, the switch actuator itself can be designed to move in various ways for stability and reliability, and may be used in either single pole, single throw, or single pole double pole applications. 
   These and other objects, advantages, purposes and features of the invention will become more apparent from a study of the following description taken in conjunction with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of a single pole, double throw switch commonly known in the prior art; 
       FIG. 2  is a plan view of a first embodiment of the electrical switch of the present invention; 
       FIG. 3  is a perspective view of the electrical switch of  FIG. 2 ; 
       FIG. 4  is an exploded, plan view of a second embodiment of the electrical switch of the present invention adapted for mounting on an electrical circuit module substrate; 
       FIG. 5  is an enlarged top plan view of the assembled electrical switch of  FIG. 4  when in a first latched position; 
       FIG. 6  is a top plan view of the assembled switch of  FIG. 5  shown in a second latched position; 
       FIG. 7  is an exploded bottom plan view of the electrical switch of  FIGS. 4-6  shown from the side of the circuit module opposite to that in  FIG. 4 ; 
       FIG. 8  is a fragmentary, sectional view of the assembled switch taken along plane VIII—VIII of  FIG. 5 ; 
       FIG. 9  is a sectional view of the assembled switch taken along plane IX—IX of  FIG. 5 ; 
       FIG. 9A  is a sectional view of the assembled switch taken along plane IXA—IXA of  FIG. 5 ; 
       FIG. 10  is a perspective view, shown partially exploded, of a second embodiment of the electrical switch adapted to operate lamps on a circuit module mounted in an interior rearview mirror assembly for vehicles; 
       FIG. 11  is an exploded, perspective view of the electrical switch of  FIG. 10  prior to installation on the circuit module substrate; 
       FIG. 12  is a top plan view of the electrical switch of  FIGS. 11 and 12 ; 
       FIG. 13  is a bottom plan view of the electrical switch of  FIGS. 11 and 12 ; 
       FIG. 14  is a sectional side elevation of the electrical switch of  FIGS. 10-13  when mounted on the circuit module substrate taken along plane XIV—XIV of  FIG. 10 ; 
       FIG. 14A  is an end view of the switch actuator of the electrical switch of  FIGS. 10-14  taken along plane XIVA—XIVA of  FIG. 11 ; 
       FIG. 15  is a sectional side elevation of the assembled electrical switch taken along plane XV—XV of  FIG. 10 ; 
       FIG. 16  is a sectional side elevation of the assembled electrical switch taken along plane XVI—XVI of  FIG. 10 ; 
       FIG. 17  is a perspective view of an interior dome lamp assembly for vehicles incorporating a pair of switches of the present invention; and 
       FIG. 18  is an exploded, perspective view of one of the switches of  FIG. 17  prior to installation in the dome lamp assembly. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings in greater detail,  FIG. 1  shows a schematic illustration of a conventional, single pole, double throw switch in which electrical current from contact A is moved between alternate contacts B and C by means of a movable switch contact D. FIG.  1  illustrates the general principle of the operation of the electromechanical switches of the present invention, although the present switch may also be used as a single pole, single throw switch when only one or the other of contacts B and C is actually connected to an electrical circuit. 
   With reference to  FIGS. 2 and 3 , a first embodiment  10  of the electrical switch of the present invention includes, a first pole or electrical switch contact  12  formed as part of an insert molded stamping that is integral with the desired product substrate for a lamp assembly or other accessory or control useful in vehicles. Contact  12  corresponds to point A in FIG.  1 . Positions B and C of  FIG. 1  correspond to contacts or stop members  14  and  16  in FIG.  2 . Preferably, one of stop members  14  and  16  is connected to the electrical circuit of the vehicle and forms a second electrical switch contact. Stop members  14 ,  16  are upstanding portions of metal, electrically conductive bus bars or circuit members insert molded in the product substrate. A resilient, flexible electrically conductive spring member  18  is engaged with contact  12  and extends laterally from contact  12  along a first arm or portion  20  of the spring member to a second arm or portion  22  of the spring member extending at a right angle to portion  20 . Second portion  22  of the spring member includes a cylindrical contact member  24  extending downwardly and adapted to be moved successively between stop members  14  and  16  to open and close the circuit between contact  12  and that stop member  14 ,  16  which is connected to the electrical circuit of the desired product substrate. 
   Preferably, stop member  14  includes portions  14   a ,  14   b  extending at a right angle to one another for receipt of contact member  24  when it is moved into engagement with that stop member. Extending in an intermediate position between stop members  14  and  16  is an upstanding, generally heart shaped, non-electrically conductive, contact directing member  26  having angled cam surfaces  28 ,  30  which extend at different angles to stop member  16 . Extending outwardly from the contact directing member is an end extension  32  which is adjacent to but spaced from stop member  14  as well as a rigid member  34 . Rigid member  34  is adapted to engage contact member  24  as explained hereinafter. 
   Operation of switch  10  is accomplished by applying a force in the direction of arrow E ( FIGS. 2 and 3 ) causing flexing of the flat spring member  18  along first arm portion  20  in the direction of arrow F (FIG.  3 ). Thereafter, contact  24  engages inclined or angled cam surface  28  causing the second portion  22  of spring  18  to flex outwardly in the direction of arrow G (FIG.  3 ). As the force applied in the direction of arrow E continues, contact  24  slides along and is cammed laterally outwardly by surface  28  such that it passes around end extension  32 . The resiliency of the spring arm  22  snaps contact  24  in the opposite direction against rigid member  34  as contact  24  clears the end of extension  32 . Such snapping action and engagement with rigid member  34  creates an audible click or sound indicating to the switch operator that the spring has reached its second position. Release of pressure from arrow E allows the resiliency of spring arm  20  to move contact  24  back toward its first position along rigid member  34  into the space between the end of rigid member  34  and stop member  14  until the contact member comes to rest in the corner between portions  14   a ,  14   b  of stop member  14 . In the event stop member  14  is connected to the electrical circuit of the product to be operated by the switch, it is also desirable to connect rigid member  34  with the electrical circuit such that rigid member  34  is electrically conductive like stop member  14 . The engagement of contact member  24  with rigid member  34  as described above makes electrical contact between contact  24  and rigid member  34  thereby closing the desired circuit. When the force E against spring member  18  is released, contact member  24  moves downwardly along rigid member  34  and snaps into the corner between contact/stop member portions  14   a ,  14   b  in a fraction of a second such that the electrical current is not noticeably interrupted or affected, especially if the circuit is connected to a lamp or bulb. All pressure in the direction of arrow E may then be released such that contact member  24  is retained in and thus latched in the position of stop member  14 . Should it be desired to unlatch and open the circuit controlled by switch  10 , force is again applied in the direction of arrow E causing contact member  24  to move along portion  14   a  of stop member  14  past the end of that stop member. The resiliency of spring arm  20  urges contact member  24  downwardly along cam surface  30 . At the end of cam surface  30 , contact member  24  moves back to its original position ( FIG. 2 ) due to the resiliency of spring arm  22  and the fact that contact  24  passes the end of cam surface  30  to the left of its normal rest position against stop member  16  as shown in FIG.  2 . Another audible sound or click is created when contact member  24  passes the end of cam surface  30  and snaps against stop member  16  to indicate a return to its initial position. 
   It is also possible to connect stop member  16  to the electrical circuit such that stop member  14  and rigid member  34  are not connected electrically to the circuit. Therefore, spring member  18  will conduct electricity from first electrical switch contact  12  to stop member  16  thereby closing the desired circuit in the first latched position of spring  18 , while movement of contact  24  by flexing the spring as described above along cam surface  28 , around projection  32  and into stop member  14  opens the circuit in the second latched position. The circuit will thus remain open while contact  24  engages stop member  14  until it is again actuated to return the contact member along cam surface  30  to its initial position against stop member  16  as shown in FIG.  2 . Accordingly, successive movement of the conductive spring member  18  between its two positions shown in  FIGS. 2 and 3  not only latches the switch in one position or the other until again actuated by a force E, but also provides the current carrying member of the switch which opens and closes the circuit between first electrical switch contact  12  and either stop member  14  or  16  depending on which is connected electrically to the desired circuit. This is an application of a single pole, single throw switch. Alternately, both stop member  14  and  16  can be connected to the electrical circuit to operate the same accessory, motor or the like in different phases, or to different circuits for two different accessories, functions or the like. In such case, the switch would operate as a single pole, double throw switch. 
   Referring now to  FIGS. 4-9 , a second embodiment  40  of the electrical switch of the present invention is adapted for incorporation in an insert molded substrate  42  which is adapted to be mounted and assembled with the desired end product such as a rearview mirror assembly, lamp assembly or other accessory or control in a vehicle. In the embodiment shown in  FIGS. 4-9 , substrate  42  is a circuit module adapted for assembly in a rearview mirror assembly and includes a molded, polymeric plate preferably formed from nylon or another suitable thermoplastic polymeric material and having an extension  45  at one end through which project the formed, electrically conductive, metallic, spring-like flanges of a bulb holder  46  formed integrally with stamped circuit members  48 . Circuit members  48  preferably comprise brass, steel or other metallic bus bars which are insert molded within non-conductive polymeric plate  42  and include upstanding flanges  50 ,  52 ,  54  and  56  projecting through openings in plate  42  at various positions adjacent switch  40 . Switch  40  includes only two movable parts, namely, a switch actuator  60  comprising a movable button or plunger and a coil spring  80  adapted for mounting on switch actuator/button  60 . 
   Switch actuator or plunger  60  is non-electrically conductive, is a molded member preferably formed from acetal or another suitable thermoplastic, polymeric, non-conductive material in one piece, and is preferably adapted to be slidably received over edge  44  of circuit member or substrate  42  adjacent flanges/contacts  50 ,  52 ,  54  and  56 . Actuator  60  includes a pair of parallel mounting flanges  62 ,  64  spaced from one another and defining a space  66  matching the thickness of circuit substrate  42  adjacent edge  44  (FIGS.  8  and  9 ). Projecting outwardly from an upstanding flange  68  at one end of mounting flange  62  is a button or actuating member  70  adapted to be pressed by the finger of an operator toward and away from edge  44  of substrate  42 . Formed integrally on the outer surface of mounting flange  62  is cylindrical, spring mounting post  72  and an angled, upstanding spring engaging member  74 . Spring engaging member  74  includes a short, base section  74   a , adjacent spring post  72 , and an angled spring engaging section  74   b  having an upstanding face  74   c  (FIG.  6 ). Preferably, post  72  includes a slightly enlarged head  73  at its outer end to retain spring  80  thereon when telescoped over post  72  as explained below. 
   Spring member  80  is a coil spring having coils  82  aligned axially on axis M ( FIG. 7 ) and including an arm  84  extending outwardly from one end of the spring and a second arm  86  extending outwardly from the opposite end of the spring. Arm  86  includes a contact member  88  extending at right angle to arm  86  at its outer end ( FIGS. 4 ,  7  and  9 A). When mounted axially over post  72 , coils  82  of spring  80  are prestressed such that arms  84 ,  86  extend in a V-shaped arrangement similar to that shown in  FIG. 5  wherein spring arm  84  engages base section  74   a  of projection  74  while spring arm  86  engages surface  74   c  of projection portion  74   b . This allows the spring arms to contact the proper portions of the switch arrangement on substrate  42  when actuator/plunger  60  is slidably mounted over edge  44  of substrate  42  as described more fully below. Preferably, spring  80  is formed from round, stainless steel wire and is electrically conductive. Alternately, other materials can be used for spring  80  such as phosphor-bronze. The diameter of the wire forming spring  80  is selected to allow the spring to carry sufficient current to operate electrical circuits typical in a vehicle environment yet provide a desired amount of force and resiliency. Spring  80  is designed to carry electrical loads of 50 watts or less thereby allowing the current/amperage and voltage to be varied in accordance with the desired product application. The diameter is also selected to provide the desired resiliency creating the appropriate operating force for the switch when actuator/plunger  60  is pushed and depressed so as not to require too large an operating force. In the preferred embodiment, the stainless steel wire has a diameter of 0.020 inches, and carries a maximum current of 0.81 amps and a maximum voltage of 16 volts. 
   As is best seen in FIGS.  4  and  7 - 9 , actuator  60  is adapted to be confined during its rectilinear, reciprocating movement on substrate  42  by a plurality of upstanding surfaces integrally molded with the substrate. As shown in  FIG. 4 , on the side of the substrate through which members  50 ,  52 ,  54  and  56  project, substrate  42  includes a generally square guide block  90  adjacent projecting flange  50 , and a wedge-shaped guide block  92  adjacent flange  52 . Block  92  includes an angled/inclined surface  94  adapted to engage the contact member  88  of spring arm  86  as described more fully below. Block  92  extends from a position adjacent edge  44  of substrate  42  into contact with flange  52  as shown in  FIGS. 5 and 6 . Blocks  90  and  92  include rectilinear facing surfaces which are substantially parallel to one another and are adapted to engage the generally parallel side surfaces of mounting flange  62  as shown in  FIGS. 5 and 6 . On the opposite side of substrate  42  are a pair of rectilinear guide flanges  96 ,  98  having parallel facing, inside surfaces adapted to engage the parallel side edges of mounting flange  64  (FIG.  8 ). 
   A third guide surface for sliding contact with mounting flange  62  of actuator  60  is provided by block  100  also integrally molded with substrate  42 . Block  100  includes a side surface  102  adapted to slidably guide the edge of mounting flange  62 . Surface  102  is flush with and parallel to the surface of block  92  which engages mounting flange  62 . In addition, block  100  includes an upwardly inclined, cam surface  104  ( FIG. 9A ) adapted to engage contact  88  as it moves between its operative positions as explained more fully below. Block  100  abuts one side of flange  54 . Flange  54  has an L-shape in plan view and provides a stop for contact  88  of spring arm  86  when the spring arm is engaged therewith in much the same fashion as stop member  14  in embodiment  10  of the present invention. In addition, block  100  has an extending end  106  defining the end of a cam surface  108  which a contact directing member that engages contact member  88  when the switch is moved between its operative positions. Flange  56  provides a rectilinear rigid member extending at an angle toward flange  54  but having an end edge  57  spaced sufficiently from end  106  and flange  54  to allow the passage of contact member  88  on spring arm  86  therebetween as described below. 
   Assembly and operation of switch  40  will now be understood. Spring  80  is mounted over headed post  72  such that arm  84  engages base  74   a  of member  74  while spring arm  86  engages surface  74   c  of the member  74 . The spring member is thus held in a V position. With the spring so mounted, actuator  60  is positioned in alignment between block  90  and blocks  92 ,  100  on one surface of substrate  42  with mounting flange  64  aligned between guide flanges  96 ,  98  on the opposite surface of the substrate adjacent edge  44 . Actuator  60  is then moved toward edge  44  between the guide surfaces such that contact  88  on arm  86  engages angled surface  94 . As actuator  60  is moved inwardly, contact  88  slides along surface  94  while spring arm  84  engages the edge of flange  50  (FIG.  5 ). Continued movement of the actuator flexes spring arm  86  outwardly as contact  88  slides along cam surface  94  until the end of that surface and flange  52  is reached after which contact  88  moves inwardly toward projection  74  along the surface of flange  52  until arm  86  again engages surface  74   c  of member  74  (FIG.  5 ). Downwardly extending contact member  88  thereafter holds plunger  60  in its assembled, first latched position against the resiliency of the spring arms that are slightly flexed when engaged with flange  50 , surface  74   c  and flange  52  as shown in FIG.  5 . The resiliency of the flexed spring arms urges and holds actuator  60  in that position. Flange  50  is preferably connected to the electrical circuit in substrate  42 . In the event that flange  52  is also connected to the electrical circuit via bus bars  48 , spring member  80  conducts electricity from flange  50  therethrough to flange  52  thereby completing the circuit and operating the vehicle accessory connected to the circuit. However, and optionally, flange  52  may not be connected to the circuit in which case flanges  54 ,  56  are electrically connected such that spring  80  will make electrical connection to complete and close the circuit when moved to its second latched position as described below. Either one of these alternate connections is an example of the switch connected for single pole, single throw operation. Alternately, connection of all flanges  52 ,  54  and  56  to different phases of one electrical circuit or to two different circuits would allow the switch to operate as a single pole, double throw switch. 
   Inward pressure on actuator  60  by the finger of an operator against the resiliency of spring  80  causes spring arm  84  to further flex while contact  88  engages cam surface  108  of block  100  as shown in  FIGS. 5 and 6 . Continued inward movement of the actuator/plunger forces contact member around the end  106  of block  100 . The resiliency of the flexed spring arm  86  causes the contact end  88  to snap inwardly toward member  74  until it strikes flange  56 . Such striking engagement under the force of the spring causes an audible sound or click which may be heard by the switch operator. When flanges  56  and  54  are connected to the electrical circuit, the circuit is closed at that moment thereby operating the light or other accessory. When finger pressure on actuator  60  is thereafter released, the resiliency of the spring urges contact  88  along the angled surface of flange  56  until it reaches end  57  and the opening between flanges  56 , and  106  and flange  54 , at which point spring contact  88  snaps against flange  54  creating a second audible sound or click which may be heard by the switch operator after his finger is released. Such second audible sound indicates that the switch has reached its second latched position. As mentioned above, in the event that flanges  54 ,  56  are connected to the electrical circuit, the circuit is closed at this position with contact  88  engaging flange  54  such that the light or other accessory continues to operate. The momentary interruption of current flow as contact  88  passes from flange  56  past end  57  into contact with flange  54  is so short (approximately 0.005 seconds) that no visible interruption of light from the lamp or interruption of operation of the accessory is noticed by the operator. When switch actuator  60  is moved inwardly or depressed and then released in the above described fashion at a rapid pace, the switch contact moves successively from flange  52  to flange  56  and then to flange  54  in rapid succession such that two audible sounds or clicks are heard indicating the switch has reached its second latched position shown in FIG.  6 . In this position, spring arms  84 ,  86  are more severely bent than in the first latched position shown in  FIG. 5  such that actuator  60  is held in such position, and a somewhat greater force is necessary to further depress actuator  60  to return it to its first latched position as explained below. 
   When it is desired to return the switch to its first latched position shown in  FIG. 5  from that of the second latched position shown in  FIG. 6 , actuator  60  is further depressed thereby moving contact  88  along flange  54 . When the end of flange  54  is reached by contact  88 , the resilient spring force urges it inwardly toward member  74  until spring arm  88  again contacts the surface  74   c . At this point, contact  88  is aligned with inclined surface  104  as shown in FIG.  9 A. Such movement snaps arm  86  against surface  74   c  causing another audible sound or click which may be heard by switch operator. Thereafter, when actuator  60  is released, the resilient force of the spring  80  urges the actuator outwardly due to contact between spring arm  84  and flange  50 . Spring contact  88  slides upwardly over the inclined cam surface  104  as shown in FIG.  9 A and snaps against flange  52  as actuator  60  again reaches its first latched position. Such snapping action creates a fourth audible sound or click which may also be heard by the switch operator indicating the switch has returned to the first latched position. As mentioned above, depending on which flanges are connected to the circuit in substrate  42 , the lamp or other accessory will either be “on” or “off” in the first latched position. Accordingly, movement of actuator/plunger  60  between its first and second latched positions, while spring arm  84  remains engaged with the edge of flange  50 , causes contact  88  to move between flange  52  and flanges  54 ,  56  to open and close the electrical circuit to which flanges  50  and  52  or  54 ,  56  are electrically connected with electrical current passing through the spring member  80 . Alternately, as mentioned above, all of the flanges  50 ,  52 ,  54  and  56  may be connected to electrical circuits for single pole, double throw operation. Spring  80  also serves as the motive force for retaining the switch in its first or second latched position and provides resistance against which the switch actuator is operated. 
   A third embodiment  120  of the electrical switch of the present invention is shown in  FIGS. 10-16  where like parts to those of switch  40  are shown by like primed numerals. As shown in  FIG. 10 , a pair of switches  120  is assembled to a circuit member or substrate  42 ′ which is adapted to be mounted within a rearview mirror assembly R of the type including a pair of map or reading lights L. Each light L is operated by one of the switches  120 . Each switch  120  is similar in structure and operation to switch  40 , but includes a modified mounting therebetween actuator  60 ′ and substrate  42 ′. Switch  120  includes a non-conductive switch actuator or plunger  60 ′ molded in one piece and including mounting flanges  62 ′,  64 ′ from which an L-shaped operating flange or button  70 ′ extends outwardly. A nonconductive, flexible, molded, polymeric or rubber cap  71  is slidably mounted over the projecting end of flange  70 ′ to serve as an operating surface for the actuator/plunger. In addition, an oval or round projection  70   a ′ extends through an opening in cap  71  as an indicator, especially when the cap is formed from a dark material and actuator/plunger  60 ′ is molded from a light or white polymeric material. Instead of blocks or flanges engaging the edges of mounting flanges  62 ′,  64 ′ as in switch  40  described above, switch  120  includes a central flange  65  extending between the inside surfaces of flanges  62 ,  64  as shown in  FIGS. 14 and 14A  providing actuator  60 ′ with an I-beam shape in section as shown in FIG.  14 A. Flange  65  is adapted to be received in rectilinear slot  43  formed in the edge  44 ′ of substrate  42 ′. Thus, the inside edges of slot  43  engage opposite surfaces of center flange  65  while the inside surfaces of mounting flanges  62 ′,  64 ′ engage the top and bottom surfaces of substrate  42 ′ to guide the rectilinear reciprocal movement of actuator/plunger  60 ′ as it is moved to operate the switch  120 . 
   Switch  120  is assembled and operated in substantially the same manner as switch  40  described above. With coil spring member  80 ′ mounted on headed post  72 ′ in a shallow V shape by engagement with member  74 ′ (FIG.  11 ), center flange  65  is aligned with slot  43  and actuator  60 ′ is moved inwardly over the edge  44 ′ of the substrate. Contact  88 ′ of spring arm  86 ′ moves along surface  94 ′ until it snaps inwardly over the end of flange  52 ′ into engagement with member  74 ′ thereby retaining the switch actuator in its first latched position (shown in solid in FIG.  12 ). Further inward movement of actuator  60 ′ along slot  43  causes contact member  88 ′ to engage surface  108 ′ and flex laterally outwardly until it passes end  106 ′ and snaps laterally inwardly against flange  56 ′ creating an audible sound or click. Release of the plunger allows the spring resiliency to move the plunger slightly oppositely (outwardly of edge  44 ′) until contact member  88 ′ passes end  57 ′ between flange  56 ′ and flange  54 ′ into its second latched position as shown in phantom in FIG.  12 . Depending on whether flange  52 ′ or flanges  54 ′,  56 ′ are connected to the electrical circuit, the switch  120  will close the circuit in either its first latched position or its second latched position as desired for single pole, single throw operation. Of course, single pole, double throw operation is possible if all contacts  52 ′,  54 ′ and  56 ′ are connected to one or different electrical circuits. Return of the switch to its first latched position from its second latched position is accomplished by another depression of actuator/plunger  60 ′ thereby moving contact member along flange  54 ′ until the end is reached when contact member  88 ′ snaps inwardly against member  74 ′ creating an audible sound or click and aligning the contact member with inclined surface  104 ′. Release of the actuator/plunger  60 ′ allows the resiliency of the spring to return the plunger outwardly with contact member  88 ′ passing upwardly and over the inclined cam surface  104 ′ until it snaps against flange  52 ′ in its first latched position and again creating another audible sound or click heard by the switch operator. In the event the substrate  42 ′ and switch  120  are mounted in a vehicle such as in a rearview mirror assembly, light assembly or the like with a portion of that assembly reaching line N (FIG.  12 ), indicator  70   a ′ would be visible when the switch is in its first latched position such that the cap  71  projects farther outwardly than in its second latched position. The first latched position would thus preferably be the “on” position for the circuit or light or other accessory because indicator  70   a ′ is visible. However, when switch actuator  60 ′ is moved inwardly causing the switch to move to its second latched position, the circuit would be opened and indicator  70   a ′ would not be visible, thereby preferably indicating to the switch operator that the accessory is in its “off” position. 
   As an alternative to incorporating switches  120  on a circuit module or substrate  42 ′ in an interior rearview mirror assembly R in a vehicle, switches  120  may alternately be incorporated in other vehicle accessories such as an interior dome light assembly  150  shown in  FIGS. 17 and 18 . In this application, dome light assembly  150  includes an oval or other suitably shaped frame  152  preferably molded from a polymeric material such as nylon, a series of stamped, metallic, electrically conductive bus bars  154 ,  156 ,  158  which are either secured to or insert molded within frame  152 , and a pair of electrical switches  120  assembled to the frame  152  as hereinafter described. In addition, a heat resistant, molded lens insert  160  preferably formed from polycarbonate includes lens portions  162  as well as switch apertures  164  adjacent either end of the assembly. A pair of the conductive bus bars  154 ,  158  include spring like lamp/bulb holders  166 ,  168  formed integrally with the bus bars and adapted to project through apertures  170 ,  172  formed in frame  152  for receipt of cartridge type lamps or bulbs  174  within a central, recessed area  153  of frame  152 . Lens insert  160  is adapted to snap into and be received within aperture  176  defining the central recessed area  153  of dome light assembly  150  by means of a recessed shoulder  178  (FIG.  18 ). Adjacent each end of frame  152  within central recessed area  153  is an upstanding wall  180  to which one of the switches  120  is assembled. Wall  180  includes slot  43  into which one of the switch actuators/plungers  60 ′ is slidably mounted after coil spring member  80 ′ is assembled on headed post  72 ′ in the manner described for switch  120  in  FIGS. 10-16  above. Blocks  92 ′ and  100 ′ are integrally molded on wall  180  of frame  152  near slot  43  while electrical contacts  50 ′,  52 ′,  54 ′ and  56 ′ are formed on bus bars  154 ,  156 ,  158  in similar positions to those shown in  FIGS. 10-16  when the bus bars are assembled to the frame  152 . Accordingly, each switch  120  may be operated to open and close the circuits defined by bus bars  154 ,  156  and  158  to operate individual lamps/bulbs  174  by pressing button/plunger  70 ′ covered by cap  71 ′ which extends outwardly through aperture  164  in the manner described above. Indicator  70   a ′ will preferably be visible beyond the lens insert  160  and aperture  164  when the circuit is on and bulb  174  is activated and actuator/plunger  60 ′ is in its first latched position, but be positioned below the surface of lens insert  160  when actuator/plunger  60 ′ is depressed and in its second latched position within frame  152  and lens insert  160 . Accordingly, the electrical switches of the present invention may be applied to various assemblies in a vehicle, appliance or other application to operate a variety of lamps, accessories or controls on individual circuits connected to an electrical system. 
   While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow, and interpreted under the principles of patent law including the Doctrine of Equivalents.