Optical switch

An illumination source transmits light through a transmitting light pipe to an optical switch. A first receiving light pipe is aligned with and spaced from the first transmitting light pipe to form a first gap therebetween. The switch includes a switch cap adapted to be disposed in a first position and in a second position. A first light transmitting tower is coupled to the switch cap and extends from the switch cap into the first gap when the switch cap is disposed in at least one of the first position and the second position. A first opaque blade extends from the switch cap and adjacent to the first light transmitting tower and is adapted to extend into the first gap to prevent light from being transmitted to the first end of the first receiving light pipe in one of the first position or the second position. In other embodiments, a switch and a method for using the switch enable illumination of only a portion of the switch cap regardless of the switch position. Preferably, the switch and method allow for illumination of different portions of the switch cap when the switch is in corresponding different positions.

TECHNICAL FIELD
 The present invention relates generally to switching and, more
 particularly, to an illuminated optical switch.
 BACKGROUND OF THE INVENTION
 Vehicles such as automobiles, trucks, and aircraft often include multiple
 electrical switches located on an operator control panel. Each electrical
 switch independently switches electric current flowing in copper wires to
 control a vehicle function. Such functions may include turning on a
 vehicle's lights, operating windows, etc.
 It is desirable that a switch be illuminated for improved visibility of the
 switch. A switch may be illuminated by a lamp located behind the switch.
 Illumination by a separate lamp introduces additional design and
 manufacturing costs to account for the lamp while reducing reliability due
 to possible lamp failure.
 Electrical switches function by opening or closing an electrical circuit. A
 switch is opened by separating a first electrical contact from a second
 electrical contact. A switch is closed by connecting the first electrical
 contact to the second electrical contact.
 When an electrical switch controls a high current, each opening or closing
 of the electrical circuit may cause a spark to jump between the two
 electrical contacts. This spark may blast off a portion of one of the
 electrical contacts possibly resulting in premature wear and premature
 failure of the switch. Alternatively, when a switch controls a low current
 circuit, corrosion may build up on the first and second contacts. Over
 time, the corrosion may accumulate and a switch may fail because a
 conductive path is not formed when the first and second electrical
 contacts are connected.
 SUMMARY OF THE INVENTION
 To achieve these and other objects, and in view of its purposes, the
 present invention provides an optical switch. According to an embodiment
 of the present invention, a first transmitting light pipe has a first end
 aligned with and spaced from a first end of a first receiving light,
 forming a first gap therebetween. A switch cap is adapted to be disposed
 in a first position and in a second position. A first light transmitting
 tower is coupled to the switch cap and extends from the switch cap into
 the first gap when the switch cap is disposed in at least one of the first
 position and the second position. A first opaque blade extends from the
 switch cap and adjacent to the first light transmitting tower and is
 adapted to extend into the first gap to prevent light from being
 transmitted to the first end of the first receiving light pipe in one of
 the first position or the second position.
 According to another embodiment of the present invention, an optical switch
 includes a first transmitting light pipe having a first end and a second
 end. A first illumination source is coupled to the second end of the first
 transmitting light pipe for transmitting light into the second end and
 toward the first end of the first transmitting light pipe. A first
 receiving light pipe has a first end and a second end, wherein the first
 end of the first receiving light pipe is aligned with and spaced from the
 first end of the first transmitting light pipe to form a first gap
 therebetween. A switch cap is adapted to be disposed in a first position
 and in a second position. The switch cap includes a first cap portion and
 a second cap portion. A first light transmitting is coupled to the first
 cap portion and extends from the first cap portion into the first gap when
 the switch cap is disposed in the first position and into a position away
 from the first gap when the switch cap is disposed in the second position.
 When the switch cap is disposed in the first position, light transmitted
 by the first illumination source into the first transmitting light pipe is
 transmitted through the first end of the first transmitting light pipe and
 into the first light transmitting tower to illuminate the first portion of
 the switch cap. When the switch cap is disposed in the second position,
 light transmitted by the first illumination source into the first
 transmitting light pipe is transmitted through the first gap into the
 first receiving light pipe.
 According to yet another embodiment of the present invention, a method of
 using an optical switch is provided. The optical switch includes a switch
 cap having a first cap portion. The method includes receiving light from a
 light source. The light is then directed into a gap opposite a receiving
 light pipe. The optical switch is then selectively actuated to one of a
 first position in which the light is transmitted across the gap to the
 light receiving pipe or a second position in which the light is directed
 away from the light receiving pipe. Light is transmitted from the gap to
 the first cap portion to illuminate the first cap portion when said switch
 is in at least one of the first position and the second position.
 It is to be understood that both the foregoing general description and the
 following detailed description are exemplary, but are not restrictive, of
 the invention.

DETAILED DESCRIPTION OF THE INVENTION
 Referring now to the drawing, in which like reference numerals refer to
 like elements throughout, FIG. 1 shows a control system 100 including
 optical switches 102, 104 according to the present invention.
 The first switch 102 and the second switch 104 are coupled to a controller
 106. The controller 106 controls a first load 108 and a second load 110
 responsive to signaling from the first and second switches 102, 104. FIG.
 1 shows a control system 100 having two switches 102, 104 and two loads
 108, 110. As known to those skilled in the art, the controller may be
 programmable and the present invention may have multiple switches and
 multiple loads which do not necessarily correspond to each other.
 The first switch 102 is coupled to the controller 106 by a first light
 transmitting pipe 112 and a first light receiving pipe 114. The controller
 106 includes a photodetector (not shown) for detecting an intensity of
 light received from the light receiving pipe 114. The first light
 transmitting pipe 112 and the first light receiving pipe 114 are aligned
 with and spaced from each other forming a gap 116. Signaling between the
 first switch 102 and the controller 106 is performed by first transmitting
 light along the first transmitting light pipe 112 toward the first switch
 102. The first switch 102 may then indicate a switch position to the
 controller 106 by allowing the light to be transmitted to the controller
 through the first receiving light pipe 114, by attenuating the light
 returned back to the controller 106, or by blocking the light returned
 back to the controller 106 along the first receiving light pipe 114. The
 controller 106 detects the difference or change in light intensity and
 uses the detected intensity to determine a corresponding switch 102, 104
 position. The controller 106 may then control a load such as the first and
 second loads 108, 110 responsive to the determined switch 102, 104
 position.
 The present invention is described above using light pipes comprised of
 optical quality plastic. Light pipe technology is known to those skilled
 in the art as described by the Hewlett-Packard Co. in Light Guide
 Techniques Using LED Lamps, Optoelectronics Division Application Brief
 I-003, 1-28 (1993), and described by Blumenfeld et al. in Parts That Glow
 2-11 (1959). As known to those skilled in the art, the teachings of the
 present invention may be applied using other light transmission media such
 as optical fibers.
 The second switch 104 is coupled to the controller 106 by second and third
 light transmitting pipes 118, 122 and by second and third light receiving
 pipes 120, 124. The second light transmitting pipe 118 and the second
 light receiving pipe 120 are aligned with and spaced from each other
 forming a gap 126. The third light transmitting pipe 122 and the third
 light receiving pipe 124 are aligned with and spaced from each other to
 form a gap 128.
 FIGS. 2 and 3 show exemplary configurations of light pipes according to the
 present invention. In FIG. 2, a single light source 202 illuminates first,
 second, third, and fourth transmitting light pipes 204, 206, 208, 210.
 Each transmitting light pipe 204, 206, 208, 210 has a corresponding first,
 second, third, and fourth receiving light pipe 212, 214, 216, 218. The
 transmitting and receiving light pipes in FIG. 2 are aligned with and
 spaced from each other forming gaps 220, 222, 224 and 226.
 FIG. 3 shows another exemplary configuration of light pipes according to
 the present invention. A single light source (not shown) may transmit
 light along a single base light pipe 302. First, second, third, and fourth
 transmitting light pipes 304, 306, 308, 310 may be formed by tapping off
 of the base light pipe 302. The configuration shown in FIG. 3 includes
 receiving light pipes 312, 314, 316, 318 and gaps 320, 322, 324 and 326,
 similar to those shown in FIG. 2.
 Although the light pipes in FIGS. 2 and 3 are illustrated as four pairs of
 transmitting and receiving light pipes, the present invention is not
 limited to only four pairs of transmitting and receiving light pipes. In
 practice, configurations of light pipes as shown in FIGS. 2 and 3 may be
 manufactured as a larger number of pairs of transmitting and receiving
 light pipes. For example, light pipes may be manufactured as 30 pairs of
 transmitting and receiving light pipes. According to the specific needs of
 a particular switch console, the 30 pairs of transmitting and receiving
 light pipes may be configured to accommodate any number of switches
 between one switch and 30 switches by snapping off the unneeded light
 pipes. In an exemplary embodiment the light pipes comprise an optical
 quality plastic such as polycarbonate or acrylic.
 FIG. 4 shows an expanded view of a console 402 including multiple switches
 404. A back plate 406 includes light pipes 408 corresponding to the
 switches 404. The console 402 includes plates 410 in positions where
 switches are not needed. The present invention allows a control system to
 be easily configurable by allowing the addition or removal of switches
 404. For example, plate 412 has a corresponding transmitting light pipe
 414 and a corresponding receiving light pipe 416. If an additional control
 function is desired, plate 412 may be replaced with a switch 404, and
 controller 106 (FIG. 1) may be programmed to monitor receiving light pipe
 416 and to control a corresponding load responsive to the intensity of
 light monitored from the receiving light pipe 416.
 FIG. 5 is a perspective view of a first exemplary optical switch 500
 according to the present invention. As shown in FIGS. 5A and 5B, the
 switch 500 includes a switch cap 502 and a housing 504. FIG. 5C is a cross
 sectional view of the assembled switch 500.
 In this exemplary embodiment, the housing 504 includes a first side 508 and
 a second side 510, opposite the first side 508. The housing 504 includes
 an aperture 506 in the first side 508 through which a first transmitting
 light pipe 512 extends. A similar aperture (not shown) is formed on the
 second side 510 through which a first receiving light pipe 514 extends. In
 other embodiments, the housing 504 may be sufficiently thick such that the
 light pipes 512, 514 extend only into the two sides 508, 510 of the
 housing 504.
 The first receiving light pipe 514 is aligned with and spaced from the
 first transmitting light pipe 512 forming a first gap 516 therebetween
 (see FIGS. 5D-I). The switch cap 502 is adapted to be disposed in at least
 a first position and in a second position. (i.e., with one half of switch
 cap 502 depressed, as shown in FIG. 5C, or with the other half of switch
 cap 502 depressed). One or more intermediate positions may be available by
 forming a ridge 522 in switch cap 502 which cooperates with member 524 of
 housing 504.
 A first light transmitting tower 518 is coupled to the switch cap 502 and
 extends from the switch cap 502 into the first gap 516 when the switch cap
 502 is disposed in the first position. Although not shown, the components
 could be formed on the other half of the switch such that first light
 transmitting tower 518 would extend into the first gap 516 when the switch
 cap 502 is disposed in the second position. When light transmitted along
 the first transmitting light pipe 512 is coupled to the first light
 transmitting tower 518, the first transmitting light tower 518 directs the
 light up the tower 518 to the switch cap 502 to illuminate at least a
 portion of the switch cap 502. The switch cap 502 may be illuminated or
 not illuminated depending on whether the tower 518 is in the path or out
 of the path of the light transmitted from the first transmitting light
 pipe 512. In an exemplary embodiment, the first light transmitting tower
 518 comprises optical quality plastic.
 A first opaque blade 520 extends from the switch cap 502, adjacent to the
 first light transmitting tower 518, into the first gap 516 to prevent
 light from being transmitted from the first transmitting light pipe 512 to
 the first receiving light pipe 514 in one of the first position or the
 second position. In an exemplary embodiment, the first opaque blade 520 is
 adjacent to but separated from the first light transmitting tower 518. In
 an exemplary embodiment, the first opaque blade 520 is separated from the
 first light transmitting tower 518 by a distance 526 (see FIG. 5D) ranging
 from approximately 0.01 inches to 0.06 inches. In another exemplary
 embodiment, the distance 526 between the first opaque blade 520 and the
 first light transmitting tower 518 is 0.03 inches.
 In an exemplary embodiment, an optical switch according to the present
 invention is formed without a housing 504. It is not necessary that a
 transmitting light pipe and a corresponding receiving light pipe be
 coupled to the optical switch by a housing nor that they be coupled to the
 switch by a component of the switch. For example, as shown in FIG. 4, a
 transmitting light pipe 414 and a corresponding receiving light pipe 416
 may be secured to a back plate 406. A switch without a housing may then be
 secured to the back plate 406 so its first opaque blade 520 extends from
 the switch cap 502 adjacent to the first light transmitting tower 518 into
 the first gap 516 to prevent light from being transmitted from the
 transmitting light pipe 414 to the receiving light pipe 416 in one of the
 first position or the second position.
 FIGS. 5D-I are cross sectional views of the switch 500 taken along line
 C--C in FIG. 5C. FIGS. 5D-I illustrate different exemplary configurations
 of the length of the first light transmitting tower 518 in combination
 with different orientations of the first light transmitting tower 518 and
 the first opaque blade 520 with respect to the first transmitting and
 receiving 512, 514 light pipes. Each pair (i.e., FIGS. 5D/5E, 5F/5G, and
 5H/5I) shows the same configuration in different switch positions.
 When the first transmitting light tower 518 is in the path of the light
 transmitted from the first transmitting light pipe 512, the switch cap 502
 is illuminated and the switch cap is defined to be "on". When the first
 opaque blade 520 does not extend into the first gap 516, the switch is
 defined to be "on". Table 1 below illustrates whether the switch cap
 ("cap" below) is "on" or "off" and whether the switch is "on" or "off" for
 the configurations shown in FIGS. 5D-I.
 TABLE 1
 FIG. 5D Cap On
 Switch Off
 FIG. 5E Cap On
 Switch On
 FIG. 5F Cap On
 Switch Off
 FIG. 5G Cap Off
 Switch On
 FIG. 5H Cap Off
 Switch Off
 FIG. 5I Cap On
 Switch On
 FIGS. 6A-C illustrate the structure of and FIGS. 6D-F illustrate the
 operation of a second exemplary assembled switch 600 according to the
 present invention. Each of FIGS. 6A-C show disassembled components of the
 switch 600.
 FIG. 6A shows a first light transmitting tower 602 coupled to a first
 portion 604 of the switch cap and a second light transmitting tower 606
 coupled to a second portion 608 of the switch cap. FIG. 6B shows a first
 opaque blade 612 and a second opaque blade 614 coupled to a rocker 610.
 FIG. 6C shows a housing 616. The towers 602, 606, switch cap portions 604,
 608, rocker 610, blades 612, 614, and housing 616 may be assembled to form
 a switch 600 shown in FIGS. 6D-F.
 In this exemplary embodiment, the switch 600 is adapted to be disposed in a
 first position as shown in FIG. 6D, a second position as shown in FIG. 6E,
 and in a third position as shown in FIG. 6F. In this exemplary embodiment,
 the switch 600 includes two towers 602, 606 and two blades 612, 614 and is
 configured for switching first and second pairs of transmitting and
 receiving light pipes located at positions 618 and 620, respectively. As
 known to those skilled in the art, the teachings of the present invention
 are not limited to a particular number of switch positions, towers,
 blades, or light pipes, nor do the number of towers and blades necessarily
 need to correspond to one another.
 When the switch 600 is in the first position as shown in FIG. 6D, the first
 blade 612 is in position 620 and blocks light ("off") from the second
 transmitting light pipe from reaching the second receiving light pipe. The
 light from the second transmitting light pipe is coupled through the first
 tower 602 to the first portion 604 of the switch cap to illuminate the
 first portion 604 of the switch cap ("on"). Light from the first
 transmitting light pipe is not blocked ("on") and is coupled to the first
 receiving light pipe. The second portion 608 of the switch cap is not
 illuminated ("off") because the second tower 606 is not in the path of one
 of the first or second transmitting light pipes. The illumination of the
 first and second portions 604, 608 of the switch cap and the switching of
 light in the first and second pairs of transmitting and receiving light
 pipes is summarized in Table 2 below.
 TABLE 2
 Cap Illumination Switching
 First Second Second
 Portion Portion First Pipe Pipe
 FIG. 6D On Off On Off
 FIG. 6E Off On Off On
 FIG. 6F On On Off Off
 In an exemplary embodiment, a monochromatic light source transmits light of
 a first color or wavelength through the first transmitting light pipe and
 another monochromatic light source transmits light of a second color or
 wavelength through the second transmitting light source. This results in
 the illumination of the switch cap being illuminated with a different
 color depending on the position of the switch.
 FIG. 7 shows a rotary switch 700 according to an exemplary embodiment of
 the present invention. A light source 702 transmits light into an end of a
 transmitting light pipe 708. The opposite end of the transmitting light
 pipe is aligned with and spaced from a first receiving light pipe 710 and
 a second receiving light pipe 712, forming a gap 714 therebetween. The
 first and second receiving light pipes 710, 712 are adapted to transmit
 light received from the transmitting light pipe into a first photodetector
 704 and second photodetector 706, respectively.
 A switch cap 716 is coupled to and controls the rotation of a disk 718. The
 switch 700 is indexed to have four positions and for one of four positions
 of the disk 718 to be in the gap 714 in each of the four positions. Each
 of the four positions may block ("off") or let pass ("on") light from the
 transmitting light pipe 708 to one or both of the receiving light pipes
 710, 712.
 Each of the four positions has a corresponding indicator (or cap portion)
 "1", "2", "3", and "4" on the switch cap 716 which may be illuminated.
 Each indicator may be illuminated by a light tower 720. The light tower
 720 in FIG. 7 corresponds to indicator "4". For clarity, light towers
 corresponding to other indicators are omitted from FIG. 7. When the switch
 cap 716 is rotated to its fourth position, the light tower 720 will be
 within the path of light transmitted from the transmitting light pipe 708
 and will couple the light to for illuminating the indicator "4".
 As known to those skilled in the art, the light tower 720 may comprise an
 optical quality plastic so light from the transmitting light pipe 708 is
 transmitted through the light tower 720 to its corresponding indicator
 while also being coupled to one or both of the receiving light pipes 710,
 712 depending on the position and configuration of the disk 718.
 As known to those skilled in the art, a switch 700 as shown in FIG. 7 may
 include four light towers 720 each corresponding to a separate indicator
 which are coupled to a single disk (not shown) of optical quality plastic
 in the switch cap 716. Light transmitted along the tower 720 will provide
 the brightest illumination to its corresponding indicator which light will
 also dissipate into the disk to provide a lesser amount of illumination to
 the remaining indicators.
 Switches according to the present invention are not limited to a particular
 number of positions. For example, the rotary switch 700 in FIG. 7 may be
 adapted to have more or less than 4 discrete positions. As known to those
 skilled in the art, the number of receiving light pipes may be
 correspondingly increased or decreased with the number of positions of the
 switch.
 The teachings of the present invention are not limited to rocker switches
 as shown in FIGS. 5 and 6 or to rotary switches as shown in FIG. 7. For
 example, a switch similar to that described above with regard to FIGS.
 6A-F may be configured as a toggle switch 800 as shown in FIG. 8 or as a
 slide switch 900 as shown in FIG. 9.
 The toggle switch 800 shown in FIG. 8 includes a housing 816, a first blade
 812, a first light transmitting tower 802, a second blade 814, and a
 second light transmitting tower 806 similar to switch 600 in FIGS. 6A-F.
 The toggle switch 800 has a first cap portion 804 and a second cap portion
 808. The towers 802, 806 and blades 812, 814 are configured for switching
 first and second pairs of transmitting and receiving light pipes located
 at positions 818 and 820. The switch 800 is shown in FIG. 8 in a position
 similar to switch 600 shown in FIG. 6F and both the first and second cap
 portions 804, 808 are "on" and both the first and second pipes are "off".
 The toggle switch 800 may be actuated to the left and to the right into
 positions similar to those shown in FIGS. 6D and 6E to provide
 illumination and signaling as shown in Table 2.
 The slide switch 900 in FIG. 9 includes a housing 916, a first blade 912, a
 first light transmitting tower 902, a second blade 914, and a second light
 transmitting tower 906 similar to switch 600 in FIGS. 6A-F. The slide
 switch 900 has a first cap portion 904 and a second cap portion 908. The
 towers 902, 906 and blades 912, 914 are configured for switching first and
 second pairs of transmitting and receiving light pipes located at
 positions 918 and 920. The switch 900 is shown in FIG. 9 in a left
 position where the second cap portion 908 is "on" and the first pipe is
 "off" similar to the position of switch 600 shown in FIG. 6E. The slide
 switch 900 may be actuated to a center position similar to switch 600
 shown in FIG. 6F and to a right position similar to switch 600 shown in
 FIG. 6D to provide illumination and signaling as shown in Table 2.
 The present invention is described above as providing discrete switching
 illumination steps and discrete signaling steps. As known to those skilled
 in the art, the teachings of the present invention may be adapted to
 provided non-discrete or linear illumination and signaling. For example,
 as shown in FIG. 10, a switch 100 may include a tower and/or blade 1002
 which is tapered to allow non-discrete variations in light intensity
 transmitted to the controller through a receiving light pipe and to allow
 non-discrete variations of intensity of illumination of the switch cap.
 The present invention provides a less expensive and more reliable switching
 apparatus and method than conventional electrical switching and
 illuminating techniques. A cost savings is provided because rather than
 routing copper or other conductive wires to each switch, a less expensive
 plastic light conductor may be routed to each switch. Rather than using an
 independent electrical circuit to provide illumination to a switch, the
 present invention allows a single light conductor to be used for the dual
 purpose of signaling and illumination of the switch.
 An optical switch according to the present invention is not subject to the
 corrosion in low current circuits nor wear due to sparks in high current
 circuits as described above with regard to electrical switches. In
 addition, optical signaling has improved reliability due to its immunity
 to EMI (electromagnetic interference) and RFI (radio frequency
 interference). Because EMI and RFI are prevalent in automotive vehicles
 and aircraft, the present invention is particularly well-suited for use in
 automotive vehicles and aircraft.
 The teachings of the present invention may be applied to vehicles
 including, but not limited to, automobiles, trucks, aircraft, construction
 vehicles, marine vehicles, and agricultural vehicles. Although the
 teachings of the present invention are described with regard to vehicles,
 the teachings of the present invention are not limited to vehicles and are
 generally applicable to switching applications.
 The teachings of the present invention may be implemented using switches
 having an appearance and providing tactile feedback similar to electrical
 switches. The present invention allows for cost savings due to reduced
 manufacturing and assembly costs because a standard mold may be used to
 form a standard configuration of transmitting and receiving light pipes.
 The standard configuration may then be easily adapted to a particular
 application by cutting off light pipes that are not needed.
 The present invention is described above using a single light source to
 transmit light along multiple transmitting light pipes. Alternatively, an
 independent light source may be used to transmit light along each
 transmitting light pipe.
 In an exemplary embodiment of the present invention, an incandescent light
 source is used to transmit light along the transmitting light pipes. In an
 exemplary embodiment, a color filter may then be used in combination with
 or coupled to a light transmitting tower to provide colored illumination
 of a corresponding portion of a switch cap. Alternatively, a colored blade
 adjacent to a light transmitting tower may be used to cause colored light
 to be transmitted by a light transmitting tower to provide colored
 illumination of a portion of a switch cap. Alternatively, a colored
 polycarbonate film may be placed under or printed onto a portion of a
 switch cap to provide colored illumination.
 Although illustrated and described above with reference to certain specific
 embodiments, the present invention is nevertheless not intended to be
 limited to the details shown. Rather, various modifications may be made in
 the details within the scope and range of equivalents of the claims and
 without departing from the spirit of the invention.