Abstract:
A mode selector apparatus according to the invention includes a variable output device, a control circuit responsive to the output device, and a user perceivable indicator responsive to the control circuit. The control circuit reads the output from the output device to determine if the output indicates a valid mode. If the output of the output device indicates a valid mode, the control circuit controls the user-perceivable indicator to indicate to a user that the mode selector is operating in a valid mode, and generates a valid mode indicating signal at a valid mode indicating output of the apparatus.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the priority, under 35 U.S.C. § 119, of U.S. Provisional Application No. 60/357,298, filed Feb. 15, 2002, entitled “Mode Selector Apparatus,” which is incorporated in its entirety herein by reference. 

   FIELD OF THE INVENTION 
   The invention relates to electromechanical devices in general and more particularly to mode selectors. 
   BACKGROUND OF THE INVENTION 
   Currently available mode selector devices are configured so that a user actuates a member to make and/or break electrical contacts. For example in a mode selector apparatus  700  as shown in  FIG. 7 , three fixed contacts  702 ,  704 , and  706  are provided together with a movable metal contact  710  actuateable by a sliding knob  715 . The movable metal contact  710  is movable by a user to be selectively contactable with at least two of the three fixed contacts  702 ,  704 , and  706 . When metal contact  710  is in contact with first and second pads  702  and  704 , a first valid mode is established. When metal contact  710  is in contact with second and third contact pads  704  and  706  a second valid mode of selector apparatus is defined. When metal contact  710  is in contact with only one or either of contact pads  702 ,  704 , and  706  an invalid, or null mode of selector device is established. Mode selector apparatus  700  includes mechanical detent mechanisms  720  which provide a user feedback respecting the position of contact  710 . When a user actuates sliding knob  715  from a position in which a first valid mode is defined to a position at which second valid mode is defined, the user is made aware of the movement by the click sound and the click feeling generated by detent mechanisms  720 . 
   Mode selector apparatus of the prior art have numerous limitations. It is seen that prior art mode selector  700  includes a number of intricate and interrelated parts. The intricacy of these component parts leads to a high cost for the apparatus, increases the likelihood of a mechanical failure of apparatus  700 , and therefore decreases the reliability and expected life of mode selector  700 . The electrical contacts of mode selectors wherein electrical contacts are made and broken by manual movement of a mechanical member are especially susceptible to wear, poor accuracy, and failure. “Accuracy” of a mode selector as referred to herein shall refer to the likelihood that the mode selector is actually operating in the mode of operation indicated by a position feedback element of the selector. The large number of component parts of prior art mode selector  700  further increases the space consumed by mode selector  700 , thereby rendering it inappropriate in certain applications requiring a small sized mode selector. 
   There is a need for a mode selector apparatus which is highly reliable, highly accurate, low cost, and small sized. 
   SUMMARY OF THE INVENTION 
   According to its major aspects and broadly stated the invention is a highly reliable high accuracy low cost mode selector apparatus which can be made in a small size, for packaging into products wherein space is restricted. 
   A mode selector of the invention includes a variable output device in communication with a control circuit which includes at least one output and which in turn is in communication with an indicator which indicates the mode of operation of the mode selector. 
   In one specific embodiment a DC voltage which is variable by adjustment of knob of a potentiometer is converted and input into a control circuit which has been preprogrammed to determine whether the input voltage is in a range indicative of a valid mode. If the converted input voltage into the control circuit is indicative of a valid mode, the control circuit controls a mode indicating output port of the control circuit to output a signal indicative of the valid mode being established. Further, an indicator may be responsive to the mode indicating output port or another signal whose state depends on the mode of operation of the mode selector apparatus so the user is provided with user feedback as to which mode the mode selector apparatus is presently in, as is determined by the position of the potentiometer knob. The indicator is conveniently provided by an LED or other light source. The visual feedback provided by the light source indicating that a certain mode has been realized replaces the “feel” feedback provided by the detent mechanism of the prior art mode selector apparatus. 
   A mode selector apparatus of the invention can have more than one valid mode. For example, a mode or apparatus select device of the invention can have a first valid mode established when the converted input voltage into the control circuit is indicative of a first valid mode and a second valid mode established when the converted input voltage into the control circuit is indicative of a second valid mode, and a Nth valid mode established when the input voltage into the control circuit is indicative of an Nth valid mode. A mode selector apparatus of the invention can also have one, a plurality of, or no “invalid” modes of operation. An invalid mode of operation as referred to herein is a mode of operation wherein no output port controlled by the control circuit is controlled to indicate a valid mode. 
   An important aspect of the invention is that a hysteresis is built into the mode indicating system of the mode selector apparatus to accommodate slight changes in the variable output device, e.g. potentiometer output voltages attributable to e.g. temperature changes, aging, or source voltage changes. In accordance with the invention, the exit condition input value range associated with a given valid mode is made wider than the enter condition input value range, and is made to encompass the enter condition range so that slight changes in the voltage input into the control circuit attributable to factors other than the variable output device being intentionally moved do not erroneously cause the mode of operation of the mode selector apparatus to change. 
   Numerous advantages are yielded by the invention. A mode selector of the invention includes a reduced number of mechanical components and thus can be made more inexpensively than prior art mode selectors while exhibiting a longer life, higher accuracy, and greater reliability. Further, potentiometers, particularly those that are free of any mechanical position indicators intermediate the low and high and stop-limit value points, are commonly available in very small sizes as is the case with integrated circuit processors and LED indicators. Accordingly, it can be seen that the invention, particularly when comprised of a PCB mounted output device, an IC processor, and a surface mount LED can be made in an extremely small size fittable in virtually any constrained space operating environment. 
   These and other details, advantages, and benefits of the present invention will become apparent from the detailed description of the preferred embodiment hereinbelow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a physical schematic layout diagram of an embodiment of the invention comprising an potentiometer, an IC chip including an AD converter and a CPU, and a lamp; 
       FIG. 2  is an electrical block diagram of an embodiment of the invention including a potentiometer, an AD converter, a control circuit comprising a CPU, and an LED indicator; 
       FIG. 3  is a map for illustrating the invention illustrating possible wiper positions of a rotary potentiometer of the invention correlated with binarized inputs, and operating modes, associated with the various wiper positions; 
       FIG. 4  is a flow diagram illustrating operation of a control circuit programmed in accordance with the invention in one embodiment; 
       FIG. 5  is an embodiment of the invention expressed in generic form; 
       FIG. 6  is an embodiment of the invention including PCB mounted components. 
       FIG. 7  is a prior art mode selector apparatus including mechanical position indicating mechanisms. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention is described in detail with reference to  FIGS. 1-6 . Mode selector apparatus  10  in the embodiment of  FIGS. 1 and 2  includes a potentiometer  12 , also known as a variable resistor, and associated supply voltage, +V. In communication with potentiometer  12  is a control circuit  20  including a CPU  30 . Further, a valid mode indicator  60 , 62  is responsive to control circuit  20 . Control circuit  20  in the embodiment of  FIG. 1  is disposed on an IC chip  25  which also comprises, in the embodiment of  FIG. 1 , an AD converter  22  for converting analog voltages from potentiometer  12  into digital form so that the output of potentiometer  12  can be read and processed by CPU  30 . Control circuit  20  further includes a system RAM  32  mainly for storing working data and a system ROM  34  mainly for storing program data for operating mode selector  100 , as will be described further herein particularly with reference to FIG.  3 . System RAM  32  and ROM  34  in the embodiment of  FIG. 1  are provided on IC chip  25 . However, it will be understood that in another embodiment, RAM  32  and/or ROM  34  could be provided in discreet devices. 
   Control circuit  20  in the specific embodiment of  FIGS. 1 and 2  drives two valid mode outputs, a first valid mode output  36  and a second valid mode output  38 . In the embodiment of  FIGS. 1 and 2 , mode selector  100 , includes two “valid modes” of operation. However, it will be understood that mode selector  100  could also have one valid mode or more than two valid modes. In the specific embodiment of  FIG. 1  valid mode outputs  36 ,  38  are provided on pins of IC chip  25 . 
   During a valid mode of operation, control circuit  20  causes output  36 , 38  corresponding to a given valid mode to exhibit a state indicating that selector  100  is operating in that mode. Typically, control circuit  20  writes a LOGIC 1 value to output e.g.  36  to indicate a valid mode, but could also write a LOGIC 0 to output e.g.  36  to indicate a valid mode and otherwise write a LOGIC 1 to output  36  when mode selector  100  is not operating in the particular valid mode. Mode selector  100  is typically disposed to be a part of a larger circuit, wherein the valid mode outputs  36 , 38  are in communication with circuit elements of the larger circuit so that valid mode outputs  36 , 38  control some aspect of the operation of the larger control circuit. In just one illustrative example of the invention, mode selector  100  can be utilized to control a voltage rating for the line voltage powering the larger circuit in which apparatus  100  is incorporated. Moving potentiometer  12  into a first valid mode position  71 , as indicated in  FIG. 1  may adapt the larger circuit to be powered by a 120V AC line voltage, while moving the potentiometer  12  into a second valid mode position  72  would adapt the larger circuit for use with 230V AC line voltage. If potentiometer  12  is not in a position necessary to establish either of the valid modes, neither of the valid mode outputs  36 , 38  is in a state indicating a valid mode. 
   Further aspects of the invention are described with reference to  FIG. 3  showing a flow diagram illustrating the operation of control circuit  20  when operating in accordance with a program stored in system ROM  34 , and  FIG. 4  showing a map illustrating possible positions of potentiometer  12  correlated with corresponding input values and modes of operation of mode selector  100 . At block  310 , control circuit  20  reads the voltage output from potentiometer  12 . As is indicated by  FIG. 4 , the converted output voltage may have input values ranging from binary 0 (00000000) to binary 255 (11111111), when control circuit  20  includes an 8 bit processor. Continuing with reference to the flow diagram of  FIG. 3 , control circuit  20  at block  312  determines whether the input voltage read from potentiometer  12  is in valid mode entry condition input value range, e.g., binary B82 to binary B99 as indicated in  FIG. 3  for valid mode  1 , illustrated in  FIGS. 3 and 4 . If control circuit  20  at block  312  determines that potentiometer  12  is in a entry condition range of valid mode indicating positions, control circuit  20  at block  314  may turn on LED  64  and charge the state of output e.g.  36  to indicate that a valid mode has been established, and then read another potentiometer input value at block  316 . At block  318  control circuit  20  determines whether the input value (the value output by device  10 ) read at block  316  is in an exit condition range of valid mode indicating values. In the example of  FIG. 4  valid mode 1 includes an exit range of between binary B72 and binary B109. If the variable device output value is outside of the exit condition range, control circuit  100  turns off LED  64  at block  320 , or some other indicator  60 , and change the state or output e.g.  36  before reading another value at block  310 . 
   As best seen from the illustrative map shown in  FIG. 4 , the valid modes of mode selector apparatus  100  include condition ranges that are wider than their corresponding enter condition ranges. Valid mode 1 in the example of  FIG. 4  requires an input value of between binary B82 and B99 to be initially established, but for the mode of operation to subsequently change from a first valid mode operating state, an input value outside of the range of between binary B72 and B109, must be read by control circuit  20 . Providing an exit condition range for a given valid mode wider than an enter condition range prevents the operation of mode selector  100  from being disrupted by slight input value changes attributable to for example, temperature, age, or fluctuations in source voltage which supplies supply voltage +V. It is seen in the example of  FIG. 4  that if a valid mode establishing input value is on the border of an “enter condition range” e.g. at binary B172 in the case of valid mode 2, a slight change in the input into control circuit  20  will not result in mode selector apparatus  100  switching out of a valid mode 2 mode of operation. Mode selector  100  will switch operation out of a valid mode 2 operating state substantially only if a user desires mode selector  100  to switch out of a second mode state and manifests that desire by manually moving potentiometer knob  12   k  out of a valid mode 2 position. Knob  12   k  can be finger actuated as shown in  FIG. 1  or tool driven as shown in FIG.  6 . 
   An important aspect of the invention, in one embodiment, is that potentiometer  12  (or similar device as will be explained) is devoid of any mechanism which may be termed a “feel position feedback mechanism” which aids a user in positioning potentiometer, and provides feel feedback as to the positioning of knob  12   k . In the example of prior art switch  700  as shown in  FIG. 7  “feel feedback mechanisms” which provide feedback to a user as to the positioning of slide knob  715  are provided by detent mechanisms  72 , which receive slide member  716  in various positions as slide knob  715  is moved. 
   While incorporating a feel feedback mechanism into potentiometer  12  would not be deleterious to the operation of mode selector  100 , certain advantages are yielded by selecting potentiometer  12  or other variable output devices to be a manually controlled output device devoid of any position feel feedback mechanism such as mechanisms of the prior art mode selector  700 . Most notably, potentiometer  12  can purchased at reduced cost if it does not include any feel feedback mechanisms between any full scale limiting position (if any). The example of  FIG. 4  corresponds to a potentiometer having low and high limits stop  90  defining the boundaries of full scale movement from  12   k . The size requirements of potentiometer  12  are also reduced if potentiometer  12  does not include feel feedback mechanism. Further, because manually controlled variable output devices devoid of field feedback mechanisms have fewer parts, they are expected to be more reliable, and to exhibit longer life spans than manual variable output devices that have feel feedback mechanism. 
   In accordance with the invention, in one embodiment, variable position output device  10  includes visual position feedback elements without including any feel feedback position mechanisms, thus facilitating a mode selector that is less expensive, smaller, and more reliable than prior art mode selector  700 . In  FIG. 1 , output device  12 , shown as being provided by rotary potentiometer  12  includes a housing  12   h  having marking indicators  12   i  thereon for indicating the valid mode positions of device  12 . Rotary knob  12   k  may include an alignment member  12   a  or marking  12   m , or screwdriver slot (not shown) for indicating the position of knob  12   k  relative to housing  12   h . It is understood that any of elements  12   h ,  12   i ,  12   m ,  12   a , and  12   k  can be incorporated in any output device (e.g. rotary encoder). Generic rotary output device  10 , shown in  FIG. 6  includes indicating marking  10   i  and markings  10   m  having the same function as elements  12   i  and  12   m . As alluded to previously, and in accordance with an important aspect of the invention, mode selector  100  may include a light sensor such as an LED  64  which is controlled by control circuit  20  to indicate to a user that mode selector apparatus  100  is operating in an valid mode. In embodiment of  FIGS. 1 and 2 , a user does not need a feel feedback mechanism of potentiometer  12  to be assured that potentiometer  12  is in a valid mode position since light source  62  and the combination of printed matter and member indicates to a user that mode selector is operating in a valid mode. 
   In may be advantageous to include more than one light source in mode selector  100 . For example, control circuit  20  may turn on a red LED to indicate that mode selector is operating a first valid mode and a green LED to indicate that mode selector apparatus  100  is operating in a second valid mode. In the example of  FIG. 1 , a separate pin  39  of IC chip  25  is dedicated for the control of light source  62 . However it is understood that the turning and ON and OFF of light source  62  or light sources of mode selector  100  could also be controlled by the logic state outputs output at valid mode output pins  36 ,  38 . Further, a visual embodiment of indicator  60  could be provided by an alternative device such as a graphical icon of an LCD screen, as will be described herein. 
   In addition, the position feedback function of light source  62  could be provided by an acoustic output device such as a beeper or voice recording which operates alone or in combination with position indicating light source  62  or another position indicating element. Still further, mode selector  100  may have a feel feedback device that is driven by an output by control circuit  20 . The control circuit driver feel feedback device could be provided in whole or in part by a vibrator or buzzer adapted for contact with a user which is activated when mode selector  100  operates in a valid mode. A mode selector apparatus having a feel feedback mechanism driven by an output of control circuit  20  would not require a passive mechanical feel position feedback mechanism incorporated in a manual variable output device, and therefore would feature the cost, size, and reliability advantages described therein. 
   Referring to further aspects of the invention, it will be understood that potentiometer  12  as described in  FIGS. 1 and 2  could be replaced with any manually adjustable variable output device. In the genericized depiction of the invention shown in  FIG. 5 , output device  10  indicates a variable output device which may be for example, a potentiometer with or without an integrated AD converter, or a position encoder, such as an optical encoder, or a magnetic position sensor high tolerance potentiometer having integrated AD converters are often referred to by skilled artisans as position encoders. Output device  10  may be a rotary manually operable device as shown in  FIGS. 1 ,  2 , and  6  or else may be a slide type device as in FIG.  7 . If device  10  is rotary driven, the rotating part or “knob” of device  10  may be finger actuated as shown in  FIG. 1  or else may be for example drivable by a slotted screwdriver, a phillips head screwdriver as shown in  FIG. 6 , or a hex screwdriver. Specific manufacturer-available examples of output device  10  are: MICROPOTENTIOMETER series 8 mm to 16 mm potentiometers or WR3 Series trimmer potentiometers available from Productwell Precision Electrical Co. Ltd, a Sinostar Electronic LTD 11 mm to 33 mm metal shaft position encoder, a 0.5 W Cement Trimmer Potentiometer available from Filsonic Industries LTD, or one of the many potentiometers available from Tokyo Denshi LTD such as a PRM series potentiometer, a R-16K Series potentiometer, a RM series, a SC series, a SM series, a SR series or a Slide Potentiometer, which may be cased or uncased. As seen by the part list above, device  10  may be mechanically mountable, free standing, or mountable in a printed circuit board (PCB). 
   Referring to further aspects of mode selector  100 , control circuit  20  can be provided on an IC chip including a CPU as indicated in FIG.  1 . Because the functions required of control circuit  20  are limited, control circuit  20  can be provided by an inexpensive microprocessor chip such one of the many PIC series microprocessor chips available from Microchip, Inc. or Electronix Express, Inc. One specific microprocessor IC chip which may be utilized as control circuit  20  is a 16C715 8 bit microchip having on board AD available from Microchip, Inc. Of course, control circuit  20  need not include a CPU packaged in an integrated circuit. Control circuit  20  can be provided, for example, by an analog circuit, a digital logic circuit, a hybrid circuit, and can include one or more dedicated function programmable devices such as an FPGA or ASIC. 
   Light source  62  can include any suitable illumination device including a laser light source, an incandescent lamp, or an LED  64 , such as a leaded type LED or a surface mount LED. By selecting light source  62  to be a surface mount device, light source  62  can be of a very small size. Light source  62  may be, for example, a SurfLED SML series surface mount LED, mountable in a printed circuit board (PCB) available from Ledtronics, Inc., which are available in single color, bicolor or multicolor models. Currently available SurfLED SML series LEDS consume a surface area of 3.4 mm by 2.8 mm, but smaller sizes are and will be available. 
   Referring to the specific physical representation example of the invention shown in  FIG. 6 , it can be seen that mode selector apparatus  100  can be provided in a highly miniaturized combination of PCB mounted parts. In the example of  FIG. 6  variable output device  10 , 13  is provided in a PCB mounted rotary variable output device  13  mounted on PCB  96  actuatable by a slotted screw, control circuit  20  is provided in PCB mounted IC chip  25 , and indicator  60  is provided in a surface mounted LED  64 . Variable output device  13 , IC chip  25  and LED  64  are arranged in a configuration (i.e. a first row comprising device  13  and LED  64 , and a second row comprising chip  25 ) which minimizes surface area consumption. It will be seen that by appropriate selection of available component parts, the exemplary example of the invention shown in  FIG. 6 , can readily be provided by a combination of PCB mounted parts which consume less than about 10 mm×10 mm of surface area on PCB, and with appropriate selection of parts, less than 7 mm×7 mm and smaller. 
   While the present invention has been explained with reference to the structure disclosed herein, it is not confined to the details set forth and this invention is intended to cover any modifications and changes as may come within the scope of the following claims. 
   While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawing, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.