Abstract:
An apparatus and method for sensor-based interface with feedback are provided for user input to programmable electrical systems, the sensor having a long life and high reliability and being activated by a user action, where the sensor is, for example, a photoelectric sensor, magnetic sensor, Hall effect based sensor, sensor based on capacitance change, proximity sensor, and a resistance sensor. Inputs are made in a predetermined sequence of preset ‘time windows’ by having a user, while in close proximity to the sensor, provide power to the electrical system to initiate a programming sequence and then activate the sensor one or more times in order to set the preprogrammed sequence of variable control values. Feedback of each activation as it is sensed by the sensor is provided immediately to the user, for example by a light emitting diode (LED) and default values result from lack of input.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to user input to programmable electronic devices. More particularly, the present invention is a sensor-based interface which employs changes in sensed parameters as inputs to programmable electronic devices.  
           [0003]    2. Discussion of Related Art  
           [0004]    Environmental parameters are commonly monitored by sensor apparatus to provide feedback concerning changes in these parameters that exceed predetermined tolerances. Sequential changes in such parameters can be used as inputs to programs that direct some action in response to such a sequence of changes.  
           [0005]    Programmable electronic devices are commonplace that have default settings for programmable options, including values and function choices, each of which can be revised to provide customized settings in accordance with user preferences. Typically, input to such programmable devices is provided by manually manipulating different input devices for the various programmable options and groups of options. Feedback is provided by displaying the provided input in any one of several formats such as a display screen or a function-specific lighted indicator. The trend is toward sharing displays for multiple user inputs, thereby allowing a user to review multiple such settings in a common format.  
           [0006]    Mechanically manipulated switches are the input mechanism of choice and can include sealed touch panels which act as manual switches by completing an electric circuit when touched by a user at indicated positions, as well as rocker switches, rotary knobs, and slidable indicators or the like. However, many such mechanically manipulated switches can be unreliable both in the long run and in hostile or hazardous environments and cannot be made more reliable for a low cost per control. Further, the complexity of the parameter-setting protocol contributes to the cost, overall, of user input mechanisms for programmable electronic devices. Electromechanical input devices are not cost effective for environmentally hostile or hazardous applications.  
         SUMMARY OF THE INVENTION  
         [0007]    Thus there is a need for an alternative to conventional user input mechanisms for programmable electronic devices that is both low cost and reliable over the long run and in both hostile and hazardous usage environments. The present invention provides an apparatus and method that employs a sensor to achieve a low cost user input interface that is both cost effective and reliable in all usage situations. Further, the input interface can be used to monitor the environment when it is not being used as a user input interface.  
           [0008]    Thus, the present invention provides an apparatus and method for a single sensor to fulfill two functions: as a user interface for parameter input to programmable electronic device, and as an environmental sensor. This duality of use is achieved without use of any additional input channels and without accidental modification of previously programmed parameters.  
           [0009]    In a preferred embodiment, sealed electromechanical buttons were replaced with a photosensor interface according to the present invention as an input mechanism for a garden light controller and a single LED was provided as a feedback mechanism. The resulting reduction in complexity of the printed circuit board increased reliability while decreasing the manufacturing cost by 40%. The construction of sealed buttons for use in the outdoor environment is costly due to the wide range of temperatures in which the button&#39;s moving parts must perform reliably. Further, the single LED output of this embodiment significantly decreased the number of microcontroller output pins required to indicate programmed parameters. For example, to employ widely used 7-segment LED indicators to indicate parameters in a range of 0 to 9, it is necessary to use 7 output pins compared with one LED indicator in this embodiment of the present invention. As a result, the number of required microcontroller outputs dropped, allowing the use of smaller and lower cost microcontrollers. However, the use of a single LED as an input feedback and display mechanism is only one example of a low-cost approach according to the present invention, and it would be obvious to one skilled in the art that this single LED can be eliminated completely or replaced by a variety of display types in accordance with the requirements of the application of the present invention as a user input interface to a programmable electronic device. For example, when the device output state is indicative of the acceptance of user input, there is no need for a separate input feedback and display mechanism. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 illustrates an embodiment employing a photoelectric sensor with a single LED for feedback.  
         [0011]    [0011]FIG. 2 illustrates (a) the state of the photoelectric sensor of FIG. 1 during a typical parameter input sequence for both user input and default parameter setting, initiated by powering on the device, and (b) the corresponding output of the single LED of a device of the embodiment of FIG. 1.  
         [0012]    [0012]FIG. 3 illustrates a flow chart of one embodiment of a method for programmed control of an electronic device employing the present invention as a user input interface.  
         [0013]    [0013]FIG. 4 illustrates an embodiment of the present invention which employs a photoelectric sensor as a user input interface to a programmable low voltage load, such as a garden light controller.  
         [0014]    [0014]FIG. 5 illustrates an embodiment of the present invention which employs a reed contacts based sensor as a user input interface to a programmable low voltage load, such as a garden light controller, from a location without exposure to ambient light.  
         [0015]    [0015]FIG. 6 illustrates an implementation of the present invention that employs a Hall-effect sensor controlled by a magnet as a user input interface to a programmable device in an application requiring a sealed device housing without moving parts.  
         [0016]    [0016]FIG. 7 illustrates an embodiment of the present invention that employs a proximity sensor as a user input interface to a programmable device in an application requiring a sealed device housing without moving parts.  
         [0017]    [0017]FIG. 8 illustrates an embodiment of the present invention that employs a resistance sensor that is sensitive to the level of a substance contained in a tank as an input interface to a programmable device in an embodiment requiring a measure of the input level deviation from a known position. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]    Referring now to FIG. 1, a preferred embodiment is shown of the present invention employing a lens  10  as an input port transmitting visible light from a source (not shown) to a photoelectric sensor  10  in a user input interface controlled by a printed circuit board  13 . Also illustrated in FIG. 1 is a single LED  12  which acts to provide a visual feedback or indicator through an output port or light transparent lens  11 . In this embodiment, a photoelectric sensor  10  is enclosed in an optically opaque housing  14 . The photoelectric sensor  10  is exposed to light from a source (not shown) through a lens  11  that is transparent to visible light. In this embodiment, a user&#39;s finger  16  or any optically opaque object can be employed to interrupt light from the source from reaching the sensor  10 . Each such interruption is a discrete input in this embodiment.  
         [0019]    In this preferred embodiment of the device of the present invention, a user enters information by providing a discrete input transmitted through an input port to a sensor during a specially allocated ‘time window’ for each such piece of information. In this manner, a predetermined sequence of parameter inputs can be made by a user by allocating a sequence of finite duration ‘time windows’ to each such input. If no such input is received during a given ‘time window’ then the corresponding parameter is set to a predetermined standard/default setting. As illustrated in FIG. 1, a user receives feedback confirmation of every such input by a change in the state of a feedback indicator, such as the LED  12 .  
         [0020]    In order to begin the sequence of inputs, in a preferred embodiment, the programmable electronic device is supplied with a power source, e.g., by being plugged into an AC outlet  30 . In a preferred embodiment, as illustrated in FIGS. 2 and 3, the programmable device is energized by a power source at time T 0    20   30 , and initialization  31  of the programmable device is completed at time T 1    21 . Then, the programmable device switches into ‘programming mode’ for a preset period of ‘time window’ T 1 -T 2    32  in order to receive input corresponding to a first parameter  25 . The start of ‘programming mode’ for the first parameter  25  is indicated by turning the LED  12  ‘ON’ (not shown in FIG. 3) at time T 1    21  while the end of programming mode for the first parameter  25  is indicated by turning the LED  12  OFF (not shown in FIG. 3) at time T 2    22 .  
         [0021]    During the period of time between T 1  and T 2 , each intentional interruption of the light  34  from the source reaching the photoelectric sensor  10  is regarded as an input which results in changing the contents of a control register  36 , as shown in FIG. 3. In order for an interruption to qualify as an input not only must the light level reaching the sensor  10  have changed  33  but it must change in a given direction  34  and be debounced  35 . Only then is the content of a control register incremented  36  to indicate an input has been received. When the programming period of the ‘time window’ expires  32  the appropriate parameter will be set to the value of the control register or a default value, the latter if the control register contents are zero indicating no input received via the photoelectric sensor. For example, as shown in FIG. 2, five interruptions of the light from the source result in setting a first parameter to a value of five (5). Different final values of the control register can result in different actions when the program  37  controlling the device is run. If more than one parameter is to be input, additional parameters can be entered in an analogous manner by having a second, third, etc., window in sequence, e.g., T 3    23  followed by T 4    24 . In FIG. 2 the second window in sequence is not used for input and the corresponding second parameter is set to a ‘default’ value  26 .  
         [0022]    If another type of input port and corresponding sensor is employed, the conditions that must be satisfied for reception of a valid input will vary according to the type. However, the logic flow concept illustrated in FIG. 3 will be the same and the physical sensor and LED states will correspond to that of a photoelectric sensor, but will be particularized to the type of being used. For example, instead of light and dark, for a proximity type input port (which transmits infrared radiation from a nearby source), the presence or absence of a heat radiation increase detected by the sensor can indicate a discrete input. As one skilled in the art will realize, other types of sensors which can be used include, but are not limited to a magnetic sensor, Hall effect-based sensor, sensor based on capacitance change, proximity sensor and resistance sensor. The corresponding input port for each of these example sensors is selected for its ability to transmit a discrete input signal of the type that can be sensed.  
         [0023]    In addition to specifying the value of a settable parameter, the state of a sensor at the beginning and end of a ‘time window’ can be used to initiate special functions. For example, programming that employs a photoelectric sensor to detect input is expecting a lighted environment. Activation of the programmable device by supplying a power supply in the dark or restoration of power following a power failure can result in the programmable device entering a default mode of operation.  
         [0024]    [0024]FIG. 4 illustrates an example of a preferred embodiment of the present invention employing a photoelectric sensor for providing input to a low voltage load, such as a programmable garden light controller. The example of FIG. 4 comprises:  
         [0025]    terminals  41  and  42  to provide for incoming power;  
         [0026]    power supply  43 ;  
         [0027]    photoelectric sensor  44  of the light dependent resistor type;  
         [0028]    microcontroller  47  with crystal oscillator  46 ;  
         [0029]    inputs/outputs  48  for the main device functions;  
         [0030]    light emitting diode (LED)  49  with current limiting resistor  50 ;  
         [0031]    load control relay  52  driven by transistor  51 ; and  
         [0032]    terminals  53  and  54  for connecting the load.  
         [0033]    In this example of a preferred embodiment, incoming  12  VAC through terminals  41  and  42  is applied to the power supply  43  and to the load through normally open contact relay  52 . Power supply  43  provides 5 VDC and 12 VDC necessary for the programmable device to function. Light dependent voltage divider comprises photoelectric sensors  44  and resistor  45  and the resulting voltage is applied to the input PB 3   61  of microcontroller  47 . In this example of a preferred embodiment, port PB 3   61  is configured as an input with pull down resistor disabled. Microcontroller  47  recognizes the voltage level on input PB 3   61  as either ‘HIGH’ or ‘LOW’ and analyzes inputs and controls outputs according to the control program loaded into the device.  
         [0034]    The device of the example preferred embodiment of FIG. 4 provides visual feedback via LED  49  and is the simplest and least expensive means for indicating feedback by using a sequence of flashes and pauses of variable duration. Output PA 7   62  controls relay  52  using transistor  51  and the relay&#39;s contacts control power to the load connected to terminals  53  and  54 .  
         [0035]    When power is first applied to the device, microcontroller  47  performs the initialization process, setting up the proper internal configuration for device operation. After completion of the initialization process, microcontroller  47  switches to programming mode during which every interruption of light from the source (not shown) to the photosensor  44  is regarded as a discrete input. The duration of programming mode is preset by the control program. After expiration of this preset programming duration, microcontroller  41  switches to nominal mode, during which mode all changes to light reaching photosensor  44  are regarded as a parameter being monitored by the device. In the preferred embodiment employing a photosensor as an input device for a garden light controller, the control program turns power ON to the load at dark and turns power OFF to the load at dawn or after some preset time after dark has expired.  
         [0036]    The cost of the printed circuit board assembly in this example embodiment was reduced by almost 40% and the reliability was increased. In this embodiment, space requirements also were decreased over a prior implementation of sealed electromechanical buttons.  
         [0037]    [0037]FIG. 5 illustrates a preferred embodiment in which the sensor is a reed contacts based sensor  47 , controlled by a magnet. This embodiment can comprise a sealed device housing for hostile usage environments.  
         [0038]    [0038]FIG. 6 illustrates a preferred embodiment using a Hall-effect sensor  58 , also controlled by a magnet. This embodiment improves on the embodiment of FIG. 5 derived from the reliability of solid state technology used to produce the sensor. Further, this embodiment allows the device to be incased in a sealed device housing without moving parts, further improving on the device of the embodiments of FIG. 5.  
         [0039]    [0039]FIG. 7 illustrates an embodiment employing a proximity sensor  59 , sensitive to the position of specific input media. This embodiment provides the advantage of a greater variety of input media than that of the embodiment of FIG. 6 while still allowing the device to be encased in a sealed device housing without moving parts.  
         [0040]    [0040]FIG. 8 illustrates an embodiment employing a resistance sensor  60 , sensitive to the level of a substance in a tank. The advantage of this embodiment is that level deviations during the programming mode can be used to specify permitted level deviations during the nominal mode.  
         [0041]    While certain embodiments have been presented in which this invention provides an input interface to a programmable electronic device, these are illustrative only and are not limiting in any sense. That is, this invention is not limited to use with programmable electronic devices. As one skilled in the art will realize, other applications of the invention are possible. By way of example only, the device of the present invention can be used for monitoring ambient levels of particular parameters with an indicator for displaying changes in values of monitored phenomena when changes exceed predetermined threshold values, e.g., an alarm sounds when a temperature exceeds a prespecified value.