Patent Publication Number: US-2002003206-A1

Title: Remote and integrated optical sensing of state, motion, and position

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority of provisional application Ser. No. 60/067,381, filed Dec. 3, 1997, entitled, “Interactive Panels for Instrument Control,” assigned to the assignee of the present application, and which is incorporated herein by reference. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] This invention relates generally to sensing state, motion, and position in an electronic system, and more particularly use of optical signals for remote sensing of state, motion, and position in an electronic device.  
       [0003] Optical sensors are used in a variety of devices to sense the presence or absence of objects and the motion or position of objects. In a typical optical sensor, an emitter is provided which transmits a beam of light through a medium, such as infrared or visible light. A detector is used to sense the presence of the emitted beam of light. In “make beam” sensors, the detector normally detects no beam, and then detects the beam of light after it has been reflected from a reflective surface moved into the path of the beam. In “break beam” sensors, the detector normally detects the beam, and then detects the absence of the beam after an object or surface is placed to block the beam. In both types of optical sensors, no electrical or mechanical contact is made when sensing, thus allowing the sensor to have a long life without the wearing of parts.  
       [0004] Optical encoder sensors sense motion by providing a dark-light encoder pattern that causes the detector to alternately detect and not detect the beam; by counting the number of detections, an amount of movement can be determined. Quadrature encoding makes use of two detectors that are spaced in accordance with the encoder pattern so that the second detector receives light 90 degrees out of phase with the first detector. By comparing the two detected beams, the direction of motion can be determined. Optical encoders are used in may types of devices, including computer mice, trackballs, joysticks, or any other device in which motion, position, and/or direction of a member or component is sensed.  
       [0005] Optical fibers are used to direct light from one location to another, and can be useful for illuminating particular locations when an emitter must be remotely located from that location. The optical fiber is a discrete fiber having a cladding sheathing a light-conducting core to allow light to be transmitted from one end of the fiber to the other end. As an alternative to fiber optics, optical channels can be molded into an appropriate solid material. For example, optical channels can be used for illuminating buttons and other features on backlighting panels, such as panels manufactured by Lumitex Corp. of Strongsville, Ohio. In these panels, one or more point light sources (usually LEDs) are potted in a clear epoxy cement into one edge of a thin acrylic panel. Their visible light is beamed into the panel and is directed upward as required by particular treatments and processes. These panels are used for backlighting overlays, control panels, and other user interfaces in which visible illumination is required.  
       [0006] One problem in many devices that use optical encoders to sense motion or position is that space is limited so that emitters and/or detectors of the encoders cannot be easily placed near an encoder wheel or control surface. Some manufacturers have used optical fibers to allow more compact designs for encoders. For example, iO Tek of Seoul, Korea manufactures an optical-fiber computer mouse that employs infrared LED emitters local to the encoder wheel and uses optical fibers to conduct reflected light from the encoder wheel to remote photodetectors. Since the optical fibers can be flexed in any desirable angle, this allows the encoder to be used in very slim and compact device designs.  
       [0007] A problem with the existing use of optical fibers to conduct optical signals for encoding and detection purposes is that the fibers are hand-assembled in the housing of the device. This assembly process requires a significant amount of time and thus increases the cost of the device. In addition, such an assembly process may be suitable for first-stage production or low-volume products, but many high-volume applications can require higher levels of integration and automation for cost-effectiveness. What is needed is a more efficient, integrated optical sensor and switch that is suitable for high-volume, low cost manufacturing.  
       SUMMARY OF THE INVENTION  
       [0008] The present invention provides optical sensors and switches that allow remote sensing and thus convenient placement in an electronic device and which include integrated optical channels for high-volume, low cost manufacturing.  
       [0009] More particularly, an optical sensor of the present invention includes a substrate or support structure, a moving member having an encoder pattern, and an emitter that outputs a beam of electromagnetic energy. A detector channel formed integrally in the substrate receives the beam when the encoder pattern permits the beam to reach the detector channel. A detector located remotely from the encoder pattern receives the beam from the detector channel and outputs an electronic signal indicating that the beam is being detected. Preferably, the emitter is also located remotely from the encoder pattern, where an emitter channel formed integrally in the substrate directs the beam from the emitter to the encoder pattern on the moving member.  
       [0010] The moving member can be a wheel rotatable about an axis or a linearly-moving member, for example. The moving member pattern can include a number of gaps and a number of blocking portions, where the gaps allow the beam to be transmitted to the detector channel. Or, the encoder pattern can include a number of portions having a reflective surface and a number of portions having a less reflective surface, such that the detector can distinguish which portion reflects the beam. The substrate is preferably made of plastic transparent to the beam, and the detector and emitter channels are molded in the substrate, such that at least one wall of the channels is reflective. In one embodiment, at least two walls of a channel are bordering an air gap in the substrate. The emitter and detector can be integrated in a lead frame array. A second detector and second detector channel may also be included to allow the sensing of direction of the moveable member. A method of the present invention provides similar features to the apparatus described. A different embodiment of an optical sensor of the present invention includes a flexible ribbon and flexible optical light pipes coupled to the ribbon, instead of the substrate and integral channels of the above embodiments.  
       [0011] An optical switch of the present invention includes a portion of a panel having a recess and an emitter outputting a beam of electromagnetic energy, where the emitter is coupled to the panel and is located remotely from the recess. An emitter channel is integrated in the panel and directs the beam from the emitter to the recess. A detector channel integrated in the panel receives the beam in a first state of the switch, and the detector channel does not receive the beam in a second state of the switch. A detector is located remotely from the encoder pattern and receives the beam from the detector channel. The detector outputs an electronic signal indicating one of the states of the switch.  
       [0012] Preferably, the detector channel receives the beam when a user causes an object, such as a finger of the user, to be placed in the recess such that the beam is reflected to he detector channel. Alternatively, the detector channel constantly receives the beam from the emitter until a user breaks the beam with an object, such as a finger, and the detector no longer receives the beam. The panel can be made of plastic transparent to the beam, where the detector channel is molded in the substrate, such that at least one wall of the channel is reflective. An illumination channel can also be molded in the panel which directs visible light from a second emitter located remotely from the recess to illuminate the recess when one of the states of the switch is entered.  
       [0013] Another embodiment of an optical switch of the present invention includes a moveable control movably coupled to a panel, where the control is manipulable by a user. An emitter located remotely from the control outputs a beam of electromagnetic energy and an emitter channel integrated in the panel directs the beam from the emitter to the control. A detector channel integrated in the panel receives the beam when the control is moved such that the beam is modulated to the detector channel. A detector located remotely from the control receives the beam from the detector channel and outputs an electronic signal indicating a state of the switch. For example, the control can include reflective and non-reflective portions about its circumference for reflecting the beam, or gaps to allow transmission of the beam. The control can be a rotary knob or a linear moving control. The optical channels can be implemented as described above.  
       [0014] The optical sensors and switches of the present invention provide accurate, reliable sensing devices which are cost-effective and easy to manufacture. The emitters and detectors can be positioned remotely from the moving element, thus allowing a great range of flexibility in placement of the encoder in suitable electronic devices. The optical channels of the encoders used for directing beams from emitters and to detectors are highly integrated and thus very suitable for automated, high-volume, and low cost manufacturing. The emitter and detector arrays described herein may be seated in the encoder substrate and allow further integration for even further decreases in cost and increases in automation and production.  
       [0015] These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0016]FIGS. 1 a  and  1   b  are top and side schematic views, respectively, of a first embodiment of an optical encoder of the present invention for sensing motion or position;  
     [0017]FIG. 2 a  is a perspective view of a suitable integrated optical channel for use with the encoder of the present invention;  
     [0018]FIG. 2 b  is a side elevational view of a support forming an optical channel in a substrate;  
     [0019]FIGS. 3 a  and  3   b  are top plan and side views of a second embodiment of an optical encoder of the present invention;  
     [0020]FIGS. 4 a  and  4   b  are top and side views, respectively, of a third embodiment of an optical encoder of the present invention;  
     [0021]FIGS. 5 a  and  5   b  are top plan and side views of a fourth embodiment of an optical encoder of the present invention;  
     [0022]FIG. 6 is a top plan view of a fifth embodiment of an optical encoder of the present invention;  
     [0023]FIGS. 7 a  and  7   b  are side elevational views of a sixth embodiment of an optical encoder of the present invention;  
     [0024]FIGS. 8 a  and  8   b  are top plan and side elevational views, respectively, of a seventh embodiment of an optical encoder of the present invention;  
     [0025]FIG. 9 a  is a top plan view of a tape for use with an optical encoder;  
     [0026]FIG. 9 b  is a top plan view of an eighth embodiment of an optical encoder of the present invention include a tape of FIG. 9 a;    
     [0027]FIGS. 10 a  and  10   b  are side elevational views of a break beam optical switch of the present invention;  
     [0028]FIGS. 11 a  and  11   b  are side elevational views of a make beam optical switch of the present invention;  
     [0029]FIGS. 12 a  and  12   b  are top plan views of panels using the optical switches of FIGS. 11 a  and  11   b;    
     [0030]FIG. 13 is a top plan view of a panel using the optical switches scanned in a grid;  
     [0031]FIG. 14 is a side elevational view of a panel including optical switches of the present invention;  
     [0032]FIG. 15 is a top plan view of a panel including optical switches and illumination of key recesses;  
     [0033]FIGS. 16 a  and  16   b  are top plan views of an optical switch of the present invention including a linear-moving control;  
     [0034]FIG. 17 is a top plan view of an optical switch of the present invention including a rotary knob control;  
     [0035]FIGS. 18 a  and  18   b  are top plan and side elevational views, respectively, of a panel for use in a vehicle and including optical circuits and controls;  
     [0036]FIGS. 19 a  and  19   b  are top plan and side elevational views, respectively, of a panel for use in an audio module and including optical circuits and controls; and  
     [0037]FIGS. 20 a  and  20   b  are side elevational views of a hybrid panel including both electronic circuits and optical circuits.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0038] The optical sensing devices described herein are generally provided as either motion-sensing encoders and state-sensing switches.  
     [0039] Optical Encoders FIG. 1 is a schematic diagram of a first embodiment of an optical encoder  10  of the present invention. Encoder  10  includes a code wheel  12 , an emitter  14 , a detector assembly  16 , a substrate  20 , and channels  22   a  and  22   b . Code wheel  12  is a cylinder that is rotatable about an axis A with respect to the other components of the sensor. The code wheel  12 , for example, may be rotatably coupled to the substrate  20  or to a different surface grounded relative to the wheel&#39;s rotation. The wheel includes on its cylindrical side a regular coded pattern  24 , such as regularly-spaced black and white (or dark and light) marks, where one type of mark is able to reflect emitted light, and the other type of mark absorbs or reflects light to a lesser degree that is sufficient to allow a detector to discriminate between the two levels of beam intensity. A detector can also be made to detect and discriminate between more than two intensities of the reflected beam for greater resolution. Such encoder wheels are well known to those skilled in the art.  
     [0040] Emitter  14  is positioned to direct electromagnetic energy, such as infrared or visible light, to the side of the code wheel where the pattern  24  is located. Emitter  14  is grounded with reference to the wheel  12 . The emitter can be any of a variety of types of optical components, including a LED, photodiode, etc. The emitted light beam from emitter  14  is shown as arrows  26 . The light is directed into channels  22   a  and  22   b  of the substrate  20 . Substrate  20  is a support structure preferably made of a low-cost plastic, such as acrylic, or similar material which can be formed or altered with molds. Substrate  20  is a transparent material to the beam emitted by the emitter  14 , allowing a desired wavelength of light to be transmitted through the substrate.  
     [0041] Channels  22   a  and  22   b  are integrated in the monolithic substrate  20 . Herein, the term “channel” is intended to refer to a path of light within a substrate that is controlled and defined by features provided in the substrate. For example, channels  22   a  and  22   b  can be a pathway defined by walls molded into the substrate, as shown in FIG. 2 a.    
     [0042]FIG. 2 a  shows one example of a molded channel  22  that is formed or integrated in the substrate  20  and which is suitable for use with the present invention. Channel  22  is defined between two air gaps  28  which are spaced apart by a predetermined distance D. The gaps  28  each have an inner surface  30  bordering the channel  22  which is polished to a smooth finish. The inner surfaces  30  act as reflective surfaces to any light entering the channel. Thus, if light enters the channel  22 , it will move down the channel in direction  32  since the reflective inner surfaces prevent the light from moving in other directions. One advantage of using reflective walls in the channel is that the light may be directed much further without the significant scatter attenuation that would occur without reflective walls. In other embodiments, third and/or four walls can be provided to further surround the desired pathway of the light beam. The channel  22  can also be routed at different angles and curved or angular pathways, with angled reflective surfaces placed at appropriate angles to direct the light in the desired directions. The light may be both reflected and refracted (e.g., using materials of differing densities) to direct it in desired directions. Channel  22  may also be tapered, where one end of the channel is wider than the other end. The techniques for making such molded channels and providing light control within a substrate such as a panel are well known; for example, the making of such channels in materials to provided a path for emitted light is performed by Lumitex Corp. of Strongsville, Ohio, which make optical channels for illuminating plastic panels.  
     [0043]FIG. 2 b  illustrates one example of making a channel  22  in substrate  20 . A mold section  34  is provided in a mold for plastic substrate  20 . Mold section  34  includes two ribs  36  having a small width and spaced apart at a desired width for the channel. When heated, soft plastic of substrate  20  is flowed into the mold cavity, the plastic flows around the ribs  36  and cools so that so that gaps  28  are formed around the ribs  36  in the solidified plastic. When the substrate  20  is removed from the mold section  34 , air gaps  28  remain in place. Since the ribs  36  are provided with very smooth, polished surfaces, the surfaces of the air gaps  28  are also smooth, which is desirable to provide reflective properties (only the surface of the gap  28  facing the channel need be smooth and reflective). In other embodiments, the molded channels can be formed by precisely molding or inserting elements having reflective surfaces within the substrate. For example, instead of providing air gaps  28 , thin elements can be inserted into the plastic, the elements having highly polished surfaces on the sides facing the channel to contain a light beam within the channel area.  
     [0044] In other embodiments, channels  22   a  and  22   b  can be implemented in other ways. For example, a beam of light can be directed through the substrate without reflective walls, and integrated molding features such as reflective surfaces can be provided in the substrate which are angled to direct the light in a desired direction. Such a channel embodiment is described below with respect to FIG. 7 a  and  7   b . In such an embodiment without walls parallel to the light path, other features such as a molded slit and/or a molded lens can be provided at the emitter, pickup points, and/or detector to direct the light to the desired location (and if angled reflected surfaces are made narrow enough, they can act like slits to direct only light beams aimed directly at the reflective surface). Other types of channels may include baffling walls which do not reflect the light beam but prevent the beam from interfering with other optical circuits and detectors. In still other embodiments, reflective walls as described above need only be provided over a portion of a light beam&#39;s path and not the full length of the path, e.g. only at the points where the light is directed around curved or angled paths.  
     [0045] Referring back to FIG. 1, two channels  22   a  and  22   b  are provided in a phased relationship and each directs a separate light beam. The two channels are preferably spaced apart by a small distance to allow the ends of the channels to both pick up light from single emitter  26 . In an alternate embodiment, two emitters can be used, one emitter for each channel  22 . A small gap is provided between the channels  22  and the code wheel to allow the code wheel to be rotated. The channels  22   a  and  22   b  direct the light  26  emitted by emitter  26  along the length of the channels. Channels  22   a  and  22   b  are shown as curved in the described embodiment to emphasize that the light beams can be directed along a path of any shape as dictated by the constraints of packaging, housing, etc. of a device, panel, etc. Detector assembly  16  is positioned to receive the light from the channels  22   a  and  22   b . Assembly  16  includes detectors  38  and  40 , where detector  38  receives the light from channel  22   a  and detector  40  receives the light from channel  22   b . Detectors  38  and  40  can be any of a variety of light-sensing detectors, such as photodiodes, photoresistors, phototransistors, etc.  
     [0046] Encoder  10  operates as an optical reflective encoder to sense the amount and direction of rotary motion (or position) of code wheel  12 . The light  26  is only transmitted through the channels  22   a  and  22   b  when a white (or other reflective) mark of pattern  24  receives the emitted light, and the light is not transmitted when a non-reflective mark of pattern  24  receives the light. Motion of code wheel  12  is sensed by determining how many marks have been detected during rotation of the wheel. Preferably, two detectors  38  and  40  and two detector channels  22   a  and  22   b  spaced at a predetermined distance apart at their receiving ends are used to provide quadrature encoding, which allows the direction of motion of code wheel  12  to be determined as well as the amount of rotation of the wheel, and is well known to those skilled in the art. Wheel  12  can be coupled to any rotating member such that the position of the rotating member is known using encoder  10 . For example, the wheel can be coupled to a rotating member in an interface device to a computer, where the position of the interface device controls the position of a cursor in a computer-displayed graphical environment. The encoder  10  can also be used with known methods for increasing resolution, such as refractive prismatic code wheels and interrupters in place of slots or marks. In other embodiments, the positions of the emitter and decoder can be reversed, such that the emitter is located remotely from the pickup point and the detector is located local to the pickup point.  
     [0047] The encoder  10  has several advantages over other types of optical encoders. One advantage is that the detectors are positioned remotely from the pickup point (the actual point adjacent to the moving code wheel or strip at which light enters the detecting apparatus). The channels  22   a  and  22   b  may be made as long as desired for a particular application, limited only by the transmission characteristics of the medium, to allow the detectors to be positioned anywhere space allows in a device. Remote detectors allow an increase in reliability and a decrease in size and cost, as well as manufacturing simplicity and improved flexibility in package design. Another advantage is the elimination of a second pickup point for the second detector, since the channels are spaced closely enough at their pickup ends to detect a single modulated light signal at one common point. The second channel pickup is slightly offset from the first channel pickup, thereby detecting the phase differential for directional data. Another advantage is that the dimensions between the channels  22   a  and  22   b  at the pickup point can be matched to the dimensions of the moving code pattern  24  to provide a phase difference of 90 degrees at the detectors  38  and  40 , as needed for quadrature encoding, i.e. the phasing and positioning dimensions are a function of the mold of the substrate and channels. Since the channels  22  are molded in substrate  20  at the desired dimension apart in accordance with the pattern  24 , inherent optimum phasing between channels results, and there is no risk of improper distancing between the detectors and no risk of undesired movement between the detector pickup points during use of the encoder. For example, if 1 mm line width and spacing of pattern  24  is used, the openings of channels  22  at the wheel  12  can be 0.5 mm in width and positioned adjacent to each other to provide properly phased signals. Furthermore, the small size of the openings of the channels  22   a  and  22   b  allows the channels to pick up the emitted light without the use of additional precisely-positioned phasing slits or other collimating/focusing elements. Another advantage is the simplicity of the assembly of the encoder  10  of the present invention: the entire encoding circuit need only include four distinct components, light emitter, moving pattern, light channel, and light detector. Due to the inherent alignment and phasing in the encoder design, assembly may be highly automated. A final advantage is the low cost of the device: manufacturing processes suitable for automated, high-volume production and low assembly cost may be used, and the optoelectronic components (code wheels, emitters, detectors) are inexpensive and widely available.  
     [0048] In alternate embodiments, multiplexing can be used. For example, a number of code wheels and associated emitters can be provided, each having a channel  22  to a single detector (or a single pair of detectors). Each channel&#39;s code wheel is sequentially illuminated by an emitter while the synchronized detectors look for any movement of the wheel since the last scan. A microprocessor or other controller can sequentially scan several channels with a single pair of detectors. In still other embodiments, multi-phase encoding using more than two phases can be used. For example, four or eight-phase encoding can be used by adding additional channels and detectors, to allow increased sensor resolution.  
     [0049]FIGS. 3 a  and  3   b  are top plan and side elevational views, respectively, of an alternate embodiment  50  of the encoder of the present invention. Encoder  50  includes a code wheel  52 , detector assembly  54  including detectors  60  and  62 , and molded channels  58   a  and  58   b  integrated in a substrate  56 , similar to equivalent components described above with reference to FIG. 1. Code wheel  52  preferably includes gaps  66  its circumferential surface spaced according to a similar pattern as the marks of pattern  24  described for FIG. 1. In encoder  50 , emitter  64  is positioned on the opposite side of gaps  66  from the channels  58   a  and  58   b . Light  68  emitted from emitter  64  is directed at the openings  70  of the channels  58   a  and  58   b . When a gap  66  is positioned in the path of the light  68 , the light is able to reach the channels  58   a  and  58   b , and when a portion between slots is positioned in the path of the light, the light is blocked from impinging on the channels. As the code wheel  52  rotates, the light is intermittently interrupted, thus modulating the light received and transmitted by the channels  58   a  and  58   b . The operation of such transmissive optical encoders are well known to those skilled in the art.  
     [0050]FIGS. 4 a  and  4   b  are schematic diagrams of a third embodiment  80  of an optical encoder of the present invention. Encoder  80  includes a code wheel  82 , a substrate or panel  84 , an emitter  86 , and detectors  88  and  90 .  
     [0051] The periphery (circumferential surface) of the code wheel  82  is printed with a contrasting dark-light encoding pattern  92 , as shown in FIG. 4 b , and similar to the pattern  24  described above. Emitter  86  and detectors  88  and  90  are preferably integrated on a common leadframe array  94  that is cast in place in the panel  84  and has leads or traces  95 . Furthermore, other discrete elements or components may also be integrated on the leadframe array  94  with the emitter and detectors. Channels  96 ,  98  and  100  are molded into and integrated with the panel  84 . Emitter  86  outputs light, such as infrared light, which is guided by molded emitter channel  96  toward the code wheel  82 . The light illuminates the encoding pattern  92 , causing light to be reflected into the two detection channels  98  and  100  which in turn guide the light to detectors  88  and  90 , respectively. The detection channels  98  and  100  are positioned to produce quadrature phasing of the two return light beams. The detectors  88  and  90  convert the received light beams into phased electrical signals, which supply distance and direction information relative to rotation of code wheel  82  to conventional electronic circuitry.  
     [0052] The embodiment  80  has several advantages. Both the detectors and the emitters are positioned remotely from the pickup point  102  where the light reflects from the encoding pattern, allowing more efficient designs and greater flexibility in packaging. Furthermore, the emitter and detectors are integrally provided in a single leadframe array, allowing simple manufacture of the parts and high-volume production. In the fully-integrated encoder, all elements can be incorporated into the leadframe capsule except the code wheel or moving pattern. Since the emitter and detectors are positioned remotely from the pickup point, there are fewer restrictions on integration than in the prior art direct sensing structures, which have significant mounting limitations. Alternatively, the emitter and detectors can be individually potted in a clear epoxy cement onto the edge or in an aperture in the panel  84 , which can be a thin acrylic panel. The emitter and detectors thus would be surrounded by the substrate material to maximize optical coupling. This allows the emitted light to be transmitted directly into the substrate material without attenuation, and allows the detected light to be similarly transmitted directly to the detectors.  
     [0053] Another advantage of the embodiment  80  of the encoder is that the two detection channels  98  and  100  are positioned to surround the emitter channel  96 . This allows light to be detected equally on either side at each detection channel at the pickup point after the light reflects from the code wheel, rather than having one detection channel receive more reflected light than the other detection channel. This arrangement can also be used in the embodiments of FIGS. 5 and 6, and/or can be incorporated into a plastic optical panel including optical switches as described below. In alternate embodiments, the detectors  88  and  90  and the detection channels  98  and  100  can both be positioned on one side of the emitter  86  and the emitter channel  96 , similar to the encoder  110  of FIG. 5, below.  
     [0054]FIG. 5 a  is a schematic diagram of a fourth embodiment  110  of an optical encoder of the present invention. Encoder  110  includes a linear element  112 , a substrate or panel  114 , an emitter  116 , and detectors  118  and  120 . Panel  114 , emitter  116 , and detectors  118  and  120  are similar to the equivalent components as described in the embodiments above. Panel  114  includes an emitter channel  122  and two detector channels,  124  and  126 , similar to the channels described above. The two detectors and detector channels are shown positioned together to one side of the emitter  116  and emitter channel. Alternatively, an arrangement where the emitter and emitter channel are positioned between the detectors and detector channel, as shown in FIGS. 4 a  and  4   b , can be provided.  
     [0055] Linear element  112  includes a moving code element  115  which can slide in either direction in a linear degree of freedom, as shown by arrow  117 . As shown in the side view of FIG. 5 b , moving code element  115  includes a dark-light coding pattern  118  similar to the patterns described in the embodiments above, except that the pattern is printed on the straight surface of the side of element  115  rather than the curved surface of a wheel.  
     [0056] Operation of the encoder  110  is similar to the encoders described above. Light from the emitter  116  is directed down the emitter channel  122  and is directed at the element  114  at the pattern  119 , where the light is reflected from the pattern if a lighter portion receives the light and the light is not reflected (or reflected much less) when a darker portion of the pattern receives the light. Reflected light is directed to the openings of the channels  124  and  126  and to the detectors  118  and  120 . Since the openings of the channels  124  and  126  are spaced in accordance with the pattern  119  to provide proper quadrature phasing, use of the two detectors allows the determination of both magnitude and direction of motion of the moving element  115 . The element  115  can be coupled to any moving element of a mechanism or device to measure the linear motion or position of that element.  
     [0057]FIG. 6 is a schematic diagram of a fourth embodiment  130  of an optical encoder of the present invention. The encoder  130  includes a substrate or panel  132 , an emitter  134 , an emitter channel  136 , two detectors  138  and  140 , and two detector channels  142  and  144 , which emit, direct, and receive electromagnetic energy similarly to the equivalent components described above. Encoder  130  further includes a slotted code wheel  146  having a slotted surface  148 ; code wheel  146  is similar to the code wheel  52  described in FIG. 3. A fixed reflective surface  150  is preferably positioned on the other side of the slotted surface  148  from the emitter  134  and detectors  138  and  140 , and is grounded with respect to the rotating code wheel  146 . Surface  150  is positioned such that the beam  152  emitted from emitter  134  and passing through a slot in surface  148  impinges on the surface  150  and is reflected back through the surface  148  to the detection channels  144  and  142  and thus to detectors  138  and  140 . Preferably, the fixed reflective surface  150  is molded into the panel  132 , e.g., a “skirt” can extend down from the rotating wheel into a circular slot in the panel  132 , with the surface  150  molded in the center area of the skirt. Alternatively, the surface  150  can be coupled to a different grounded surface. In yet other embodiments, the surface  50  can be removed and the detectors  138  and  140  and detection channels  142  and  144  can be positioned on the opposite side of the code wheel  146  from the emitter  136 . This would allow the beam  152  to pass through the entire code wheel  146  to the detectors when slots in the code wheel are positioned appropriately, and block the beam when the code wheel is moved so that the blocking portions of the surface  148  are positioned in the path of the beam.  
     [0058]FIGS. 7 a  and  7   b  illustrate a fifth embodiment of an optical encoder of the present invention. FIG. 7 a  shows one embodiment  160  of a transmissive encoder having a vertically-aligned code wheel. A plastic frame  162  is provided which is transparent to a particular wavelength of light to be used in the encoder. An emitter  164  and a detector  166  are potted into one end of the frame  162  with an epoxy or other encapsulant. At the other end of the frame, extension arms  168  support a code wheel  170  on a rotatable shaft  172 . The emitter channel in this embodiment includes a reflective surface  174  that is integrated in frame  162  to receive a light beam  178  emitted from emitter  164  and direct the beam toward the code wheel. Similarly, the detector channel includes a reflective surface  176  is positioned in frame  162  to redirect the beam toward the detector  166 . The reflective surface can be molded into the frame  162  similarly to the channels described above, or it can be the surface of a plate or other object embedded in the frame.  
     [0059] In operation, the beam  178  is emitted from the emitter  164  and is redirected approximately 90 degrees by surface  174  toward the code wheel  170 . Code wheel  170  has slots which allow the beam to pass through the wheel, interspersed with opaque sections which block the beam. When the beam is allowed to pass through the wheel, the surface  176  redirects the beam another 90 degrees toward the detector  166 . Motion is detected by determining when the beam is blocked and when it is detected. Two detectors can be provided in embodiments having quadrature encoding, where the second detector is spaced at a distance from the first encoder in accordance with the pattern on the wheel  170 . In addition, the emitter and detector can be provided as separate components potted into a frame  162 , or they can be mounted on a common leadframe, where the reflective surfaces and codewheel support are cast into the leadframe encapsulant. Furthermore, additional features can be integrated in the frame  162  to help direct the light beams to desired locations and/or block light from interfering with other components. For example, a reflective surface or gap, or a baffle can be placed between emitter and detector to help guide the light beam to the encoder wheel and detector and to prevent any stray light from being transmitted to the detector. Alternatively, channels with walls as described in the embodiment of FIG. 1 can be used to direct the light as desired.  
     [0060]FIG. 7 b  shows another embodiment  180  of a transmissive encoder that is similar to the embodiment  160 , but includes a code wheel  194  having an orientation orthogonal to the code wheel of the embodiment  160 . In embodiment  180 , code wheel  194  is supported by a rotating shaft  195  that is rotatably coupled to an extension  196  from a frame  182 . Emitter  184  and detector  186  are placed in frame  182 , where the emitted beam  188  is reflected 90 degrees first from reflective surface  190  and then from reflective surface  192 , before the beam impinges on (or passes through) the code wheel  194  to the detector. The operation is similar to the embodiment  160  of FIG. 7 a . In alternative embodiments, the emitter and detector positions can be reversed.  
     [0061]FIGS. 8 a  and  8   b  are diagrams showing a top plan view and a side elevational view, respectively, of a sixth embodiment  200  of an optical encoder of the present invention. Encoder  200  includes a code wheel  202 , emitter  204 , and detectors  206  and  208 , similar to the embodiments above. Instead of a substrate or panel, however, encoder  200  includes a flexible ribbon  210  which can be similar to a flexible-circuit electrical interconnect ribbon in common electronic devices. The optoelectronic components such as emitters and detectors (and/or switches, traces, etc.) can be discrete elements that are adhered to the ribbon  210  with an adhesive. A film is laminated over the components, and electrical traces  218  on the ribbon can be connected to these components and terminate at connection points at the end of the ribbon. Instead of molded channels for directing light, flexible optical fibers can be positioned on the ribbon  210  to direct light. Thus, an emitter fiber  212  is laminated or otherwise coupled to the ribbon  210  so that one end picks up light from the emitter  204  and the other end directs the light onto the pattern  213  of the code wheel  202 . Two detector fibers  214  and  216  are also coupled to the ribbon  210  to receive light reflected from the pattern  203  and direct the light back to detectors  206  and  208 , where the light is properly phased for quadrature encoding.  
     [0062] The encoder  200  has several advantages. The ribbon can be very thin, allowing the encoder to placed in areas of devices having restricted space. The overall thickness of the encoder is limited by the thickness of any individual component; excluding emitters and detectors, the thickness of the wheel and fiber/ribbon need not exceed about 1 mm, for example, including 0.5 mm fibers and laminate films. Another advantage is the flexibility of the encoder. The optical ribbon may be flexed to conform to packaging requirements. Locating holes, such as holes  220 , may be die-cut into the ribbon  210  to decrease assembly times and insure precise and rapid positioning and registration with respect to the code wheel  202 . Furthermore, common production processes exist which can perform the positioning, lamination, and necessary cutting and forming at high speed and required precision.  
     [0063]FIGS. 9 a  and  9   b  illustrate a seventh embodiment of an optical encoder of the present invention. In this embodiment, a portion of the encoder is provided on a flexible strip of tape, similar to the ribbon  210  of the embodiment of FIGS. 8 a  and  8   b . As shown in FIG. 9 a , tape  230  can be provided in long lengths (e.g. stored in rolls) and can be cut to obtain a section of tape having the desired length for a specific application. Tape  230  includes an adhesive-bearing film substrate  232  on which have been laid flexible light pipes, such as optical fibers  234  oriented approximately parallel and having a size, spacing and number specified by the specific application. The optical fibers are fixed in position on the substrate by an overlay film. Periodic cutout holes  236  are preferably provided in the substrate  232 . The tape  230  may be cut at any of the cutout holes  236  to provide a tape of desired length and to allow access to the individual fibers  234  so that the fibers may be connected to appropriate components. Die-cut registration holes  238  in the substrate  232  allow rapid and precise positioning of the tape in a device relative to other components of encoder, described below.  
     [0064]FIG. 9 b  shows the placement of tape  230  in an optical encoder  240  that is used to measure motion in a device. Tape  230  has been cut to a desired size and placed in a device using registration holes  238  as a guide onto mating pins of the device; this allows rapid and precise positioning of the tape in a device relative to other components, such as encoder wheel  248  and array  242 .  
     [0065] At one end of tape  230  is placed an optoelectronic array  242 , which may include components such as emitters, detectors, fiber terminations, and electrical terminations. For example, the fibers  234  at ends  244  may be connected to terminals of emitters and/or detectors that transmit or receive light passing through the fibers. Leads  246  of the array  242  may be connected to other electrical components in the device.  
     [0066] At the opposite end of the tape  230 , an encoder wheel  248  is positioned such that light directed out of at least one fiber  234  may impinge on the pattern of the wheel and be reflected back to other fibers  234  which direct the light to one or more detectors. The pattern on the wheel is correlated to the spacing of the fibers  234  at the pickup point to provide the appropriate phase difference in detection. Code wheel  248  is coupled to a member or component that causes code wheel  248  to rotate when the member moves, thus allowing the sensing of motion of the member. In alternate embodiments, instead of wheel  248 , a linear code element may be used, similar to the linear element shown with respect to FIG. 5.  
     [0067] The assembly of the encoder  240  can be performed in a few easy steps. The tape  230  is cut to a desired length in a jig, or is provided at a precut length. The fibers  234  are then inserted into the appropriate fiber terminations on the array  242 . The tape is then inserted into the device so that the registration holes mate with registration pins of the device. The code wheel is then inserted to complete the encoder assembly. Encoder  240  allows remote emitters and/or detectors to be used in an easily-housed encoder. Since both the ribbon and the fibers are flexible, the encoder can be conveniently bent and curved to fit in particular spaces in a device, which is not possible with other forms of encoders.  
     Sensing States with Optical Switches  
     [0068] The present invention uses optical components as switches to sense states as well as motion. States to be detected include the positional state of a switch (on or off), the position of a knob (positions A, B, C, etc.), the press of a pushbutton, or the actuation of a proximity switch. Light can be modulated in transmissive or reflective embodiments by finger contact, depression of an overlay or snap dome, depression of a discrete key, or the movement of a control such as a knob or sliding switch to move gaps or encoder patterns. Optical switches may interfere with an emitted light beam to detect state (the “break beam” type) or cause a beam to be reflected to a detector (the “make beam” type), or modify the polarity of light for detection by multiple polarized sensors. A number of embodiments of optical switches follows below.  
     [0069]FIG. 10 a  is a side elevational view of an optical switch  260  in which state is sensed and the beam is modulated by breaking the emitted beam (a “break beam” type switch). A panel  262  is provided with a recess  264 . An emitter  266 , such as a light emitting diode, is positioned on one side of the recess and a light pipe  268 , such as an optical channel as described in the encoder embodiments above, directs the light from the emitter to the recess  264 . The light then is transmitted across the recess as beam  274  and is received by the light pipe  270  at the opposite end of the recess. Light pipe  270  is similar to light pipe  268 , and directs the light to a detector  272 . In the described embodiment, the light pipes  268  and  270  are substantially linear, but in other embodiments the light pipes may be curved or angled as desired to direct the light from the remote emitter  266  and to the remote detector  272 . As shown in FIG. 10 b , the user may change the state of the optical switch by simply inserting a finger or other object within the recess  264  so that the beam  274  from the emitter is broken and does not reach the detector. In some embodiments, a key or other object can be provided over the recess  264  such that when the key is pressed, the beam is blocked. For example, a flexible film overlay can be applied over the recess. When finger pressure depresses the overlay, the overlay deforms and breaks the light beam. The electronic device connected to the detector  272  can read the change in state and perform the appropriate task or function in response.  
     [0070]FIG. 11 a  is a side elevational view of an optical switch  280  in which a change in state (modulation of the light) is sensed based on the transmission of a beam to a detector (a “make beam” type switch). A panel  282  includes a recess  284 . An emitter  286  outputs a beam  288  of light which is directed by a light pipe, such as an optical channel, of the panel  282  to a reflective surface  292 . The optical channel can include a reflective surface  292  reflects the light into the recess  284 , and the beam is transmitted away from the recess so that the detector  294  does not detect the beam. In other embodiments, the beam  288  can be reflected in other directions as desired to be emitted into the recess. As shown in FIG. 11 b , a user may change the state of the optical switch by inserting a finger or other object within the recess  264  so that the beam  288  is reflected back into the panel  282  to the reflective surface  292  and is directed to the detector  294 . The electronic device connected to the detector  294  can read the change in state.  
     [0071] In another embodiment, the state of a switch can be sensed based on physical deflection of optical fibers. When an optical fiber carrying light is bent beyond a specific angle, light begins to pass out of the fiber, and the remaining light in the fiber is attenuated. The drop in light intensity can be detected as a change in switch state. For example, a pair of fibers can be laid over a recess, with light constantly being emitted at one end and detected at the other end of the fibers. The user can touch and bend the fibers when inserting a finger into the recess, causing the light attenuation and a detection of change of state. Alternatively, the optical fibers can be attached to a flexible membrane that flexes when touched, so that both membrane and fibers are bent when a user presses the keyswitch.  
     [0072]FIG. 12 a  is a schematic drawing of an example of a two-keyswitch lighted switch panel  300  using optical keyswitches of the present invention. Panel  300  includes a support  302 , on which is located an array  304 . Array  304  is preferably a single lead frame that includes all the light sources (such as emitters) for illumination and sensing state as well as all the detectors needed for sensing state. The array  304  can be embedded into the panel, such as in an optically-transparent epoxy cement, resulting in a one-piece panel component. Discrete optical components can alternatively be used.  
     [0073] Recesses  306  and  308  are provided in the support  302  as the locations of the “button” or switch for the user to activate. Light pipes  310  and  312 , such as optical channels, carry emitted, visible light from an emitter on the array  304  to the recesses  306  and  308 , respectively, to selectively illuminate the recesses. Reflective features in the recesses allow the visible light to be spread about the recess to illuminate it, as is well known to those skilled in the art. Light pipes  314  and  316 , such as optical channels, are used to transmit emitted light from different emitters on array  304  to the recesses  306  and  308 , respectively. Light pipes  318  and  320  are used to transmit light that has been reflected from an object inserted into the recess  306  and  308 , respectively, back to detectors on the array  304 . Thus the panel functions as follows, using the key of recess  306  as an example. In the key&#39;s off state, the emitted light from light pipe  314  is directed into the recess  306  and away from the detection light pipe  318 . When a user inserts a finger or object into a recess, the light from the light pipe  314  in the recess is reflected back to the detection light pipe  318  and is transmitted to a detector on array  304 , which thus detects a change in state. The keyswitch for recess  308  functions similarly. Preferably, the light from the switch emitters is not visible to the user, e.g. infrared light. The light from the illuminating emitters is visible since it used to illuminate a keyswitch; for example, a keyswitch (recess) can be illuminated after the keyswitch has been actuated (finger or object inserted), and the illumination can be turned off when the keyswitch is pressed again. In other embodiments, a break-beam type of sensor can be used instead of the described make-beam sensors.  
     [0074]FIG. 12 b  illustrates a key panel  330  similar to the panel of FIG. 12, except that nine keys  332  are provided. As described for the panel of FIG. 12 a , each of the keyswitches  332  preferably illuminates when it is actuated and then is not illuminated when the keyswitch is actuated again. An array  334  preferably integrates all the optical components for the panel, such as emitters and detectors. Light pipes (not shown) provide the light to the keys for illumination and state detection and direct light back to detectors on the array for detection.  
     [0075]FIG. 13 is a top plan view of another key panel  350  that includes an optical scanning matrix. A grid of recesses  352  in the panel  350  each function as a keyswitch in the panel. A number of emitters  354  are provided along one side of the recesses  352  and each emit a beam down a light pipe  356 , such as an optical channel, extending down each row of recesses such that one beam can be directed across all the recesses in the row. A number of detectors  358  are provided orthogonally to the emitters, and each detector receives light from an associated light pipe  359  extending down a column of recesses. The state of a switch is changed by either breaking or making a beam, as described in the embodiments above. To determine which particular keyswitch has been actuated, the emitters can consecutively emit beams in a looping or scanning fashion. When a keyswitch is actuated, the emitter scanning at the time of the actuation is noted to find the row, and the detector that detects a switch state determines the column, thus allowing the particular keyswitch actuated to be known. Such optical scanning over a grid for detection is well known to those skilled in the art. The light emitted by the emitters can also be oscillated (in any of the embodiments described herein); the emitters and detectors can operate at a high frequency to increase immunity to spurious light and increase sensor immunity to illumination within the panel, or can operate at coded frequencies (or coded intensities) to allow the light to be distinguished from interfering light.  
     [0076]FIG. 14 is a side elevational view of a panel  360  having optical keyswitches as shown in the embodiments of FIGS. 12 a ,  12   b , and  13 . Recesses  364  are provided in the panel  360 , and an integrated emitter-detector array  362  is provided at one side of the panel. Both illuminating emitters and sensor emitters are included in the array. Light channels  366  are molded into the panel  360  to direct the emitted light to keyswitch recesses and back to the detectors on the array  362 . A reflective surface  368  can be molded in the panel and used to direct the emitted beam of light through the recesses and back to the detector. The beam of light can be directed across all the recesses in a row, as in the embodiment of FIG. 13. Alternatively, each recess can be provided with its own beam of light. Furthermore, tactile, graphic, and appearance features  370 , such as rims for the keyswitches to aid the user in locating the keyswitches, may be molded and/or imprinted onto the top surface of the panel.  
     [0077]FIG. 15 is a schematic diagram of a panel  380  having selective illumination of keyswitches. Panel  380  includes a number of keyswitch recesses  382  as described above. Emitters  384  are provided at one side of the panel and emit visible light of one color. Channels  386  can be molded into the panel to direct light from the each emitter  384  to an associated keyswitch recess  382 . In some cases, the channels can use refraction or diffraction to direct the light in particular directions; for example, an air gap, having a different density than the substrate material, can refract a beam when the beam passes into the air gap. Emitters  388  can be provided at another side of the panel and emit visible light of a different color than the light emitted by emitters  384 . Molded channels  390  direct light from each emitter  388  to an associated recess  382 . Each recess  382  thus may be illuminated by either an emitter  382  or an emitter  388  (or by both emitters simultaneously). Optical switches (not shown) are also provided for each keyswitch as described in the embodiments above to detect the state of the keyswitches. When a keyswitch is in one state, it is preferably illuminated by one color of light from one emitter  384 , and when the keyswitch has another state, it is illuminated by the other color of light from an emitter  388 . In alternate embodiments, only one set of emitters can be used.  
     [0078]FIG. 16 a  is a schematic diagram of an optical linear slide switch  400  of the present invention which can be provided in panels. A panel  402  is preferably made of plastic or other moldable material. A linear track  404  in the moldable material holds a sliding or movable switch  406 , which can be toggled or adjusted by a user. An emitter  408  and a detector  410  are positioned in the panel as discrete components or as part of an array similar to the embodiments described above. An integrated emitter channel  412  directs a beam  414  of light from the emitter  408  to the track  404 . An integrated detector channel  416  is routed from the detector to the point where the channel  412  ends at the track  404 . The light beam is modulated as follows. When the switch  406  is in the off position as shown in FIG. 16 a , the beam  414  is directed into the track or is otherwise routed away from the detector channel  416 . When the switch  406  has been moved to a position that impedes the path of beam  414 , e.g. slid upward as shown in FIG. 16 b , the beam  414  reflects off a mirrored or polished surface of the side of the switch and is directed down the channel  416  to the detector  410 , where the change in switch state is detected. In other embodiments, additional emitters, detectors, and channels can be included to allow the detection of multiple states of the switch  406 . Furthermore, an optical encoder pattern can be used to detect the position of the switch  406  and/or two detectors used for direction sensing, as described in the embodiment of FIG. 5. Rocker switches can also be used instead of linearly-moving switches. In still other embodiments, a transmissive type of encoder can be provided, where an emitter located on the opposite side of the switch  406  emits light to the detectors and the light is modulated by gaps in the side of the switch, similar to the embodiment of FIG. 3 a.    
     [0079] Optical switches such as shown in FIGS. 16 a  and  16   b  have several advantages over electrical switches. The optical switches are very low cost, since the channels are easily molded in the panel and the emitter and detector components are very common. The only moving part of the switch is the sliding element  406 . If panel illumination is provided, the emitter than provides panel illumination can in some embodiments also provide the source light for the switch detection. The switch has long life since there are not electrical contact points, and has extreme environmental resistance, since it is sealed into the panel and is resistant to contamination. The optical circuit also is unaffected by any form of electromagnetic interference, such as EMI, RFI, or ESD. Remote location of electrical components can also protect users from electrical shock risk in particular environments, such as wet environments, or explosion risk in combustible environments.  
     [0080]FIG. 17 is a schematic diagram of an optical rotary switch  420  of the present invention. Similar to the switch shown in FIG. 16 a , switch  420  includes a panel  422 , an emitter  424 , an emitter channel  426 , a detector  428 , and a detector channel  430 . A rotating, circular knob  432  is provided for the user to rotate. The knob  432  can include a reflective surface on part(s) of its circumference, and a non-reflecting surface on other parts of its circumference. The knob can thus be rotated to different positions to modulate the emitted beam reflected to the detector. Multiple detectors  428  can be provided at different locations to allow multiple different settings of the knob to be detected. The knob can also be provided with an optical encoder pattern as described with reference to FIG. 1 to allow the precise position of the knob to be determined. A transmissive switch or encoder can alternatively be used, similar to te encoder as shown in FIG. 3 a.    
     [0081]FIGS. 18 a  and  18   b  are top plan and side elevational views, respectively, of an example of an automotive control panel  440  that can employ the optical encoders and switches of the present invention. Control panel  440  is commonly integrated into a dashboard of a vehicle, for example. Panel  440  may be rigid or flexible, and may be adhered to a flat or curved surface. Panel  440  may be backlighted by one set of emitters (e.g. LEDs) in the array; light is uniformly distributed. Each switch  452  (see below) may be selectively illuminated by other emitters, which illuminate the switch when the switch position is selected.  
     [0082] The front plate  442  of the panel  440  includes a number of knobs  444  and  446  and keyswitches  452 . Knobs  444  and  446  are used to control functions such as fan speed and temperature. These knobs are thus preferably provided as rotary optical encoders similar to the embodiments of FIGS. 1 and 4. Channels  448  conduct light between the knobs  444  and  446  and an emitter-detector array  450 , which is preferably the sole electrical connection point to the panel  440 . Preferably, each knob is linked to the array  450  by three channels: one to conduct light from an emitter to an encoder pattern on the knob, and two others to conduct phased light back to detectors for magnitude and direction of rotation sensing.  
     [0083] On-off keyswitches  452  are linked to array  450  by channels  454  that form a matrix, in which emitters and/or detectors sequentially scan the switches for activity. Switches  452 , for example, can control air routing in the vehicle. The switches  452  may take a variety of forms, including a linear sliding switch (FIG. 16), rocker switch, break or make beam switches (FIG. 10 and  11 ), momentary switches, etc., as required by ergonomic and/or styling considerations. Output signals from the array are digital signals that are input to a microcontroller, which decodes the signals and provides actual control voltages to effect changes in the vehicle function output. The optical switches of the present invention are advantageous in that no space behind the panel  440  is required for wiring or other components, allowing more comapact designs. There is also reduced risk of electrical leakage and shock.  
     [0084]FIGS. 19 a  and  19   b  are top plan and side elevational views, respectively, of an example of an audio mixer channel module  460  suitable for use with the optical encoders and switches of the present invention. In many digitally controlled mixers, audio signals are not brought through the module, but are remotely adjusted and switched by a microcontroller in response to movements of the panel controls. Module  460  includes a plastic panel  461 . Module  460  includes a number of latching switches  462 , rotary potentiometers  464  for selecting gain, equalization, and other parameters, and a sliding attenuator  466  for master channel gain adjustment. The attentuator  466  can be a linear sliding switch as described with reference to FIG. 16. Optical circuitry (not shown) is included in the panel  461  and an emitter/detector array  468  is provided, similarly to embodiments described above. The panel  461  can be backlit, each control can be selectively lighted, and all switches and potentiometers (knobs) can be sensed through light pipes such as optical channels as described above, where optical channels in the plastic panel conduct light between each control and the array  468 . The array converts optical signals to electrical values, which are then routed to a microcontroller, which remotely performs the switching and adjusting tasks according to the movement of the controls by the user. Optical circuits are advantageous in an audio module  460  since they are insensitive to electrical interference.  
     [0085]FIG. 20 a  shows a side elevational view of a hybrid panel  480  including integrated electrical and optical circuitry. Panel  480  includes an electrical circuit pattern  482  on the bottom of the panel. The pattern  482  can be printed on the panel according to well-known techniques. In addition, a molded optical channel  484  is embedded and integrated in the panel  482  for directing light beams. An array  486  of emitters and detectors can be coupled to or included in the panel as in the embodiments described above. A moveable push button  488  can be mounted in a recess in the panel and be spring loaded, so that downward pressure on the button closes a pair of contacts on the bottom electrical circuit, signaling a switch closure. Sliding switches may be mounted on panel  480  in a similar manner.  
     [0086]FIG. 20 b  shows a side elevational view of a hybrid panel  490  including integrated electrical and optical circuitry similar to the panel of FIG. 20 a , except that electrical circuit pattern  492  is printed on the top of the panel  490 . Pattern  492  may include a membrane keypad structure, which incorporates its own shorting-type keyswitches. The embedded optical channel  494  and emitter/detector array  496  can direct light for encoder-type controls or encoder sensors, as well as illuminate the panel and controls. In some embodiments, the electrically-conductive elements might be limited to specific sections of the panel surface where their optical opacity does not interfere with other optical panel functions.  
     [0087] The combining of conventional printed circuit boards and optical panels as in the embodiments of FIGS. 20 a  and  20   b  offers several advantages. Many techniques have been devised for the low-cost mass production of flat-panel electrical circuitry. When combined with the optical panel circuitry described herein, optimization can be achieved with respect to functionality, cost-effectiveness, structural integrity, and other factors. In alternate embodiments, rather than having electrical traces printed directly on the surface of the panel, the panel  480  or  490  may be assembled from multiple laminated layers, as is a typical membrane keyboard, where each layer can include electrical traces.  
     [0088] Hybrid circuits of this type may be more economical and practical in multifunction panels, in which encoder/potentiometers, as well as all illumination, might be linked to the emitter/detector array through light channels, as described above, and binary switches can be implemented as a simple shorting bar that contacts a printed electrical matrix, as is done in conventional membrane keypads.  
     [0089] While this invention has been described in terms of several preferred embodiments, there are alterations, modifications, and permutations thereof which fall within the scope of this invention. It should also be noted that the embodiments described above can be combined in various ways in a particular implementation. Furthermore, certain terminology has been used for the purposes of descriptive clarity, and not to limit the present invention. It is therefore intended that the following appended claims include such alterations, modifications, and permutations as fall within the true spirit and scope of the present invention.