Abstract:
A multi-positional switch that provides an immediate tactile sensation to the operator regarding the various switching positions of the switch through touch sensing includes a push button mounted to a housing which is capable of being depressed and toggled for moving a drive stem interconnected thereto into electrical engagement with either axial or radially disposed contact terminals projecting from the lower end of the housing. A toggle plate is mounted within the housing and provides a surface for the drive stem to ride upon and provide resistance in order to contact the radially disposed terminals when the push button is toggled, while depression of the push button in the axial direction causes the drive stem to pass through an aperture of the toggle plate, forcibly contacting and passing by a resistance pin subjacent the toggle plate for engaging an axial mounted terminal for conveying the tactile feel to the operator.

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to a multi-positional switch for the controls of an aircraft, and, more particularly, pertains to a multi-positional electrical switch for providing tactile feedback to the operator of the various switch positions. 
     Switches, such as push button and toggle switches, are found in everything from cameras and computer keyboards, power tools and home appliances, automotive vehicles and industrial machinery. For the above uses, as well as numerous other uses, the operator has the opportunity and time to visually observe the position of the various operational and control switches at any moment in order to confirm the particular state, engaged or disengaged, of the switch, and to obtain assurance in the form of immediate visual feedback that the switch or switches are in their proper position. 
     However, in certain work environments it may not be possible or desirable for the user or operator to carefully view and inspect the particular position of the switch due to safety and operational requirements. One example of such a work environment is in the operation and control of aircraft where the pilot, co-pilot or navigator must maintain constant vigilance in order to avoid even the slightest distraction that could lead to a fatal error and a devastating accident. Many of the switches used in aircraft are multi-contact switches wherein accuracy and stability are prerequisites for proper functioning in order for the operator to easily and accurately determine the state the particular switch is in. 
     In general a five-way switch is utilized as the conventional type of switch for aircraft. Such conventional five-way switches are configured to allow the operator to instantly sense and perceive the act and condition of switching through the perception of sounds produced by the switch contacts. However, an acute drawback in the perception of such sounds at the actual moment of switching is that the intense noise in the cockpit, combined with the fact that the operators are often wearing headsets, thoroughly obstructs the distinct perception of the switching sounds. Therefore, it is necessary for the flight operators to reliably sense the individual switching states solely through the tactile sense. 
     Thus, a number of switches have been conceived for providing a tactile and/or audible sense or feeling to the operator or user of the equipment. The Harris patent (U.S. Pat. No. 4,466,302), the Wu et al. patent (U.S. Pat. No. 4,939,327), and the Skulic patent (U.S. Pat. No. 5,057,657) all disclose keyboard switches. Harris discloses a switch actuation mechanism utilizing a stem for contacting cammed surfaces that in turn engage a rocking plate member for initiating electrical energization while Wu et al. utilizes a reciprocable plunger that actuates a leaf spring and an actuating arm for producing a tactile sense and Skulic discloses a switch actuator mechanism utilizing a cooperating plunger and slide member to create the tactile sense or feeling. 
     The Naimer patent (U.S. Pat. No. 3,539,736) discloses a switch having a reciprocable shaft with cam elements adjoined thereto, and the cam elements actuating independently shiftable armatures. 
     The Roeser patent (U.S. Pat. No. 3,772,484) discloses a dual action electrical switch wherein an actuator engages a pair of pivotally mounted switch levers for engaging the dual action switch. 
     The Metzler patent (U.S. Pat. No. 5,907,138) discloses a push-button switch having a reciprocable rod that successively engages spring biased stops each of which corresponds to an electrical contact for initiating electrical conduction. 
     The Hoskins patent (U.S. Pat. No. 5,945,647) discloses an electrical control apparatus having a control member that can establish an electrical circuit by either rotary or axial motion. 
     Nonetheless, despite the ingenuity of the above devices, there remains a need for a multi-positional switch that provides reliable, accurate, and immediate tactile feedback to the operator regarding the various switch positions to which the switch has been shifted or toggled. 
     SUMMARY OF THE INVENTION 
     The present invention comprehends a multi-positional electrical switch for use in aircraft in order to provide an immediate tactile sensation and tactile feedback to the operator regarding the various switching positions to which the switch has been moved. 
     The present invention includes a generally cylindrical housing having a manually displaceable push button mounted at the upper end of the housing. Projecting out of the lower end of the housing can be one or more radially disposed terminals and a central terminal. In addition, auxiliary contacts are adjoined to the terminals, and each auxiliary contact includes a bent portion adjacent a drive stem when the drive stem is in a non-actuated state. Secured to the push button and located at the upper end of the housing therein is a deformable cap. A guide shaft is axially mounted to the cap and includes a bore for receiving therein the drive stem that can be actuated for linear, slidable reciprocable movement and radial motion within the housing by operation of the push button. A pair of sleeves is disposed within the housing for delimiting the range of axial and radial motions of the guide shaft and drive stem. An L-shaped common terminal member is disposed adjacent the lower end of the housing and includes a rectilinear portion extending outwardly from the end of the housing and a circular portion disposed within the housing and below the guide shaft. The circular portion includes an aperture through which the drive stem can extend. Confined between an interior flange of the guide shaft and the circular portion of the common terminal member is a compression spring. 
     Closing off the lower end of the housing is a lower enclosure plate, and the lower enclosure plate supports the central terminal. The central terminal protrudes outwardly from the lower enclosure plate and is in general axial alignment with the drive stem when the push button is in the non-operational state. Disposed within the housing and supported on the lower enclosure plate is a toggle or shifting plate. The toggle plate also has an aperture through which the drive stem can extend when the push button is actuated. Located immediately below the toggle plate is a spring-mounted resistance pin for offering resistance to the drive stem as the drive stem passes through the aperture of the toggle plate for contacting the central terminal. 
     By manipulating the push button the operator can move the drive stem against the toggle plate in a radial direction so that the drive stem contacts the auxiliary contacts for electrical energization and switching. When the operator applies a downward force in the axial direction, the drive stem is forced through the aperture of the toggle plate contacting and overcoming the resistance of the resistance pin, which the operator perceives by through the tactile sense alone. Further downward pressure by the operator&#39;s finger applied to the push button causes the drive stem to contact the central terminal. 
     It is an objective of the present invention to provide a multi-positional switch that provides an easy and immediate perception to the operator of the particular switching state of the switch through tactile sensation alone. 
     It is another objective of the present invention to provide a multi-positional switch which can be moved and toggled in both axial and radial directions and which conveys the tactile sense to the operator when external pressure exceeds a predetermined limit is applied to the switch. 
     These and other objects, features, and advantages will become apparent to one skilled in the art upon a perusal of the following detailed description and accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of the invention, it is believed the invention will be better understood from the following description, taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a multi-positional switch of the present invention; 
     FIG. 2 is a sectional view of the multi-positional switch first shown in FIG. 1; 
     FIG. 3 a  is a portion of a view of FIG. 3 b  enlarged for magnification purposes of a drive stem of the multi-positional switch first shown in FIG. 1; 
     FIG. 3 b  is sectional view of the multi-positional switch to be toggled for engaging a radially disposed contact terminal; 
     FIG. 4 a  is a portion of a view of FIG. 4 b  enlarged for magnification purposes of the drive stem toggled against a toggle plate; 
     FIG. 4 b  is a sectional view of the multi-positional switch toggled against the toggle plate; 
     FIG. 5 a  is a portion of a view of FIG. 5 b  enlarged for magnification purposes showing the toggling of the drive stem over the toggle plate; 
     FIG. 5 b  is a sectional view of the multi-positional switch toggling over the toggle plate; 
     FIG. 6 a  is a portion of a view of FIG. 6 b  enlarged for magnification purposes showing the engagement of the drive stem against a bent portion of one auxiliary contact; 
     FIG. 6 b  is a sectional view of the multi-positional switch contacting the bent portion of the auxiliary contact; 
     FIG. 7 a  is a portion of a view of FIG. 7 b  enlarged for magnification purposes showing the drive stem as the drive stem is positioned for engaging a central terminal; 
     FIG. 7 b  is a sectional view of the multi-positional switch; 
     FIG. 8 a  is a portion of a view of FIG. 8 b  enlarged for magnification purposes showing the drive stem as the drive stem passes through an aperture of the toggle plate; 
     FIG. 8 b  is a sectional view of the multi-positional switch passing through the aperture of the toggle plate; 
     FIG. 9 a  is a portion of a view of FIG. 9 b  enlarged for magnification purposes showing the drive stem as the drive stem encounters resistance from a resistance pin during downward travel of the drive stem; 
     FIG. 9 b  is a sectional view of the multi-positional switch contacting the resistance pin; 
     FIG. 10 a  is a portion of a view of FIG. 10 b  enlarged for magnification purposes showing the drive stem in engagement with the central contact terminal; and 
     FIG. 10 b  is a sectional view of the multi-positional switch contacting the central contact terminal. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrated in FIGS. 1-10 is a multi-positional switch  10  for aircraft that provides the operator with immediate feedback on the particular switching state of the switch by means of tactile sensations in the form of touch sensing of the switch  10 . The present invention is a 5-way switch that conveys immediate tactile sensations to the operator when the operator applies a given pressure to the switch  10 . 
     The multi-positional switch  10  of the present invention, as shown in FIGS. 1 and 2, includes a cylindrical casing or housing  12  having an upper end  14  and an opposite lower end  16 . The housing  12  also includes an interior chamber that extends from the upper end  14  to the lower end  16  for containing structural elements hereinafter further described. Mounted at the upper end  14  of the housing  12  is a push button  18  for selective depression and release by the operator for engagement to and disengagement from various switching positions in order to achieve electrical sensitivity and connection with other mechanical and/or electrical elements for operating the aircraft. Secured to the lower end  16  of the housing  12  is a lower enclosure plate  20 , and the lower enclosure plate  20  includes a plurality of slots or channels radially arranged about a central opening  22  that extends through the lower enclosure plate  20 . Disposed inboard of the lower enclosure plate  20 , and contiguous thereto, is support housing  24 . The support housing  24  includes a support housing opening  26  that is axially aligned with the central opening  22  of the lower enclosure plate  20 . A blind hole  28  is formed in the body of the support housing  24  and is extends inward and perpendicular to the support-housing opening  26 . Located within the blind hole  28  is a resistance pin compression spring  30  and a resistance pin  32 , both of which will be hereinafter described. The resistance pin  32  is capable of linear reciprocable movement therein and can extend partially into the support housing opening  26  of the support housing  24  when in its non-engaged disposition. The interior annular wall of the blind hole  28  also includes a stopping ledge or sill  34  that delimits the range of linear movement of the resistance pin  32 . 
     As shown in FIGS. 1-10, a common central terminal  36  is mounted to the central opening  22  of the lower enclosure plate  20  and partially projects therefrom external to the housing  12 . In addition, one or more terminals  38  are mounted to the lower enclosure plate  20  and the support housing  24 . The terminals  38  extend through aligned channels or slots of the lower enclosure plate  20  and the support housing  24  within the chamber of the housing  12  and the terminals  38  also protrude exterior to the housing  12  for making electrical contact with other electrical circuitry and elements for aircraft operation. The terminals  38  are radially arranged about the central terminal  36 . In addition, an L-shaped common terminal member  40  that may serve as the ground is mounted to the lower enclosure plate  20  and the support housing  24 . The common terminal member  40  includes an annular portion  42  that is disposed within the chamber of the housing  12  and a rectilinear portion  44  extending downwardly through the lower enclosure plate  20  and externally from the lower end  16  of the housing  12 . The annular portion  42  further defines an aperture  46  that is disposed in axial alignment with the common central terminal  36 . 
     Illustrated in FIGS. 2-10 is a switching or toggle plate  48  mounted on the support housing  24  and in axial alignment with the support housing  24  and the central terminal  36  that is secured to the lower enclosure plate  20 . The toggle plate  48  includes a toggle plate surface  49 , a toggle plate aperture  50 , and a toggle plate entry chamfer  51 . The toggle plate aperture  50  is axially aligned with the central terminal  36 . Adjoined to and in electrical contact with the portion of the terminals  38  that project within the chamber of the housing  12  adjacent the toggle plate  48  are a plurality of auxiliary contacts  52 . One auxiliary contact  52  is adjoined to each terminal  38 . Each auxiliary contact  52  has an interior pliable bent or angled portion  54  that is capable of being brought into contact with the inner portion of the respective terminal  38  to which it is adjoined. The angled portion  54  of each auxiliary contact  52  is pliable; the non-engaged state is shown in FIGS. 2-4 and the electrically engaged state is shown in FIGS. 5 and 6. 
     As shown in FIG. 2, the switch  10  includes a pair of annular interior sleeves that abut the inside surface of the housing  12  for supporting structural elements hereinafter further described. Specifically, the sleeves include a guide shaft mounting sleeve  56  and a terminal support sleeve  58 . The sleeves  56  and  58  are axially aligned with each other, and the terminal support sleeve  58  abuts the circular portion  42  of the common terminal member  40 . The guide shaft mounting sleeve  56  includes an inner annular protrusion  60  that is further defined by an interior annular ledge  62 . 
     As shown in FIG. 2, the push button  18  includes an interior boss  64  that has an inner cavity or recess  66  formed therein. Mounted to the inner cavity  66  of the boss  64  is a flexible and slightly deformable cap  68 . The cap  68  is deformable and pliable to permit toggling of the push button  18  by the operator in both the axial and radial directions. The cap  68  includes a stem portion  70  and a disc portion  72  integrally formed to the stem portion  70 . The rim of the disc portion  72  rests within an outer annular channel of the guide shaft mounting sleeve  56 . The stem portion  70  also includes an interior stem bore  74  and a stopper  76  is placed within the bore  74  at the location where the bore  74  registers with the interior cavity  66  of the push button  18 . Also disposed within the interior stem bore  74  is a drive stem compression spring  78 , and, as shown in FIG. 2, one end of the drive stem compression spring  78  is seated on the stopper  76 . 
     With reference to FIG. 2, adjoined to the stem portion  70  of the pliable cap  68  is a guide shaft  80 . The guide shaft  80  includes an annular portion  82  having an interior flange  84  and a tapered or conical portion. When the guide shaft  80  is in the non-engaged state, the annular portion  82  abuts the interior ledge  62  of the guide shaft mounting sleeve  56 . The guide shaft  80  further includes an inner passageway  86  that is in axial alignment with the annular bore  74  of the stem portion  70  of the cap  68  as shown in FIG.  2 . Although the cap  68  and guide shaft  80  are two separate elements in the preferred embodiment, it is readily conceivable that the guide shaft  80  and the cap  68  could be manufactured as a unitary component and function in the same manner as the embodiment herein disclosed. 
     As shown in FIGS. 2-10, a drive shaft or stem  88  is disposed within the bore  74  of the cap  68  and the inner passageway  86  of the guide shaft  80 . The drive stem  88  is seated on one end of the drive stem compression spring  78  and travels downward toward the toggle plate  48  when the push button  18  is depressed for engaging the terminals  38  or the central contact terminal  36 . In order to limit downward movement, the drive stem  88  includes a stopping sill or neck  90  that contacts the annular wall of the passageway  86  of the guide shaft  80 . The outside diameter of the drive stem  88  is sized so that the drive stem  88  can slide through the aperture  46  of the common terminal member  40  and the opening  26  of the support housing  24  for engaging the central contact terminal  36  as illustrated in FIGS. 7-10. Thus, the drive stem  88  is capable of selective linear reciprocable movement within the guide shaft sleeve  56  and the terminal support sleeve  58  concomitant with and actuated by the depression and toggling of the push button  18  to attain the various switching positions. The drive stem  88  includes a recess  89  into which the resistance pin  32  may seat. The drive stem  88  also includes a curved or rounded end  94 , which contacts a curved or rounded end  96  of the resistance pin or sliding plate  32  for facilitating the forcing of the resistance pin  32  by the drive stem  88  back into the hole  28 . 
     A primary or main compression spring  92  is disposed within the housing  12  and encompassed by the guide shaft mounting sleeve  56  and the terminal support sleeve  58 . The primary compression spring  92  is disposed circumjacent the drive stem  88  with a first end of the primary spring  92  abutting the interior flange  84  of the guide shaft  80  and an opposite second end seated on the annular portion  42  of the common terminal member  40 . 
     The number of contact terminals  38  and  36  may be varied for providing a switch having multiple switching positions. For example, one centrally disposed contact terminal  36  would provide 1-way switching. Two radially disposed contact terminals  38  positioned to the right and left of the centerline of the switch would provide 2-way switching. Four radially disposed contact terminals  38  installed right and left and back and front of the centerline of the switch would provide 4-way switching possible. One axially disposed contact terminal  36  and two radially disposed contact terminals  38  would provide 3-way switching and one axially disposed contact terminal  36  and four radially disposed contact terminals  38  would provide 5-way switching. Any other desirable combination of contact terminals may be used to provide the desired number of switching positions. 
     With reference to FIGS. 3-6, the operation of the push button  18  for toggling in a radial manner to bring the drive stem  88  in engagement with the toggle plate  48  and then in engagement with the auxiliary contacts  52  and the terminals  38  will first be described. If the operator depresses the push button  18  in a radial. direction, the cap  68  slightly deforms to allow the concomitant angled or rotational movement of the guide shaft  80  and drive stem  88 . The rounded end of the drive stem  88  initially comes in contact with the toggle plate  48  as shown in FIG.  4 . Continued depression of the push button  18  is impeded but the operator, by maintaining pressure on the push button  18 , causes the drive stem  80  to overcome the force of the primary spring  92  and thus the drive stem  88  continues to travel on the surface of the toggle plate  48  as shown in FIGS. 3 and 4. The additional pressure on the push button  18  can be easily sensed by the operator as an immediate tactile sensation conveyed by the operator&#39;s fingers. 
     As shown in FIG. 5, the continued movement of the drive stem  88  along the surface of the toggle plate  48  causes the drive stem  88  to contact the angled portion  54  of one auxiliary contact  52  adjoined to that respective terminal  38 . The force applied by the drive stem  88  causes the drive stem  88  to bend the angled portion  54  back against the auxiliary contact  52 . Since each contact  52  is connected to one respective terminal  38  for electrical sensing and conduction, the drive stem  88  becomes electrically sensitive with that respective terminal  38  upon attaining the position illustrated in FIG.  6 . By continuously pressing the push button  18  the drive stem  88  is maintained in the state shown in FIG.  6  and thus a very stable electrical sensitivity is achieved. With the terminals  38  arranged about the common central terminal  36  as shown in FIG. 1, the present invention provides for a five position switch. The aforedescribed actions would be repeated were the operator to toggle the push button  18  and guide shaft  80  in order to bring the drive stem  88  into contact with any of the other terminals  38 . When the force of the drive stem  88  against the bent portion  54  of the auxiliary contact  52  is released, the bent portion  54  returns to the angled disengaged state as shown in FIGS. 3 and 4. 
     With reference to FIGS. 7-10, the actions that bring the drive stem  88  into electrical engagement with the common central terminal  36  will now be described. In the standard position the drive stem  88  will be in axial alignment with the aperture  50  of the toggle plate  48 , the opening  26  of the support housing  24  and the common central terminal  36 . When the operator depresses the push button  18  in the linear downward direction the drive stem  88  passes through the aperture  50  of the toggle plate  48 . The continued downward travel of the drive stem  88  is initially hindered by the resistance pin  32  that juts into the opening  26  of the support housing  24 . As the drive stem  88  travels downward the primary spring  92  is further compressed thereby increasing the potential elastic restorative force inherent in the primary spring  92 . When the restoring force of the primary spring  92  exceeds the resistive force of the resistance pin  32  resulting from the extension of the compression spring  30  within the hole  28 , the downwardly directed force of the drive stem  88  is able to force the resistance pin  32  back into the hole  28  as shown in FIGS. 8 and 9. The drive stem  88  then proceeds downward past the resistance pin  32  with the assistance of the primary spring  92  until the end of the drive stem  88  comes into contact with the common central terminal  36 . 
     As shown FIGS. 9 and 10, the operator continues depressing the push button  18  thereby maintaining the downwardly directed force on the drive stem  88  which forces the resistance pin  32  to slide back into the hole  28  thus allowing the drive stem  88  to pass thereby. Once the resistance pin  32  has been forced to withdraw from the support opening  26 , the drive stem  88  will continue to proceed downward but now through the application of less force and with the assistance of the accumulated restoring force of the spring  92 . FIG. 10 illustrates the furthest downward position of the drive stem  88  wherein the drive stem  88  is disposed in electrical connection to the common terminal member  40 . The operator can easily and quickly perceive the state of being switched by the significant decrease in the applied force as the drive stem  88  travels past and clears the resistance pin  32  for electrical engagement with the common terminal member  40 . The drive stem  88  and the guide shaft  80  return to their disengaged state by the relaxation of the primary spring  92  upon the operator releasing his or her finger from the push button  18 . 
     The foregoing description discloses and describes a preferred embodiment for the invention, and those skilled in the art will understand that other variations and modifications may be possible and practicable, and still come within the ambit of the invention.