Abstract:
A method for controlling a clam grill that has first and second platens, said method comprising: moving said second platen toward said first platen; providing a signal in response to a detection of an impediment to the motion of said second platen; and stopping said second platen in response to said signal.

Description:
RELATED APPLICATION 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 11/146,685, filed on Jun. 7, 2005, which is a continuation-in-part of U.S. patent application Ser. No. 11/070,348, filed on Mar. 2, 2005, which application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/549,233, filed on Mar. 2, 2004. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Disclosure 
         [0003]    This disclosure relates to a cooking apparatus and method in which the relative motion of two platens is automatically controlled. 
         [0004]    2. Discussion of the Background Art 
         [0005]    Cooking apparatus that includes two surfaces generally cooks by contacting opposed sides of a food product. Cooking apparatus of this type has been used in a variety of cooker styles. For example, a clam grill uses a lower platen and an upper platen that is moveable toward and away from the lower platen. Examples of clam grills are disclosed in U.S. Pat. Nos. 6,079,321 and Re 32,994. Another style is a toaster in which one surface is a platen and the other surface is a conveyor belt. The conveyor belt and the platen can be either horizontal, vertical or at an angle therebetween. Examples of toasters are disclosed in U.S. Pat. Nos. 6,201,218 and 6,281,478. 
         [0006]    These known cooking apparatuses generally include a motion mechanism that either manually or automatically moves one platen toward another until opposed sides of the food product are contacted by the platens. For example, the clam grill disclosed in U.S. Pat. No. 6,079,321 automatically controls the motion based on a set of parameters that must be input to a controller for each type of food product. These parameters include a preset gap distance, which is the cooking distance between the two platens to accommodate food products of different thicknesses. These gap distances are set by manually inputting the preset gap distance setting into the grill control and assigning the setting to a gap button on the user interface control along with a cooking time. This set of cooking parameters (gap distance and cooking time) must be preselected before placing the food product on the grill surface. 
         [0007]    The clam grill operator must also input the type of food product being cooked so that the controller uses the parameter set for that food product. Should the operator inadvertently input the wrong type, the upper platen may not contact the food product or may put too much pressure on the food product. Since the parameter set also includes the cook time for the food product type, the food product could be undercooked or over cooked. Thus, there is opportunity for human error at the time of entry of the preset gap distances as well as at the time of selecting the type of food being cooked. 
         [0008]    There is a need for a cooking apparatus that automatically controls the relative motion of the two platens in a manner that avoids user error. 
       SUMMARY 
       [0009]    The cooking apparatus of the present disclosure comprises a first platen and a second platen and a positioning mechanism that moves the second platen toward and/or away from the first platen. A detector is disposed to provide a signal in response to detection of an impediment to the motion of the second platen. A controller controls the positioning mechanism (a) to move the second platen toward the first platen and (b) to stop the second platen in response to the signal. 
         [0010]    In one embodiment of the present disclosure, the impediment is the first platen and the signal is provided as the second platen makes contact with the first platen. 
         [0011]    In another embodiment of the present disclosure, the controller in a preheat mode further controls a heater to apply thermal energy to at least one zone of the first platen and to the second platen. 
         [0012]    In another embodiment of the present disclosure, the controller controls the positioning mechanism to maintain the second platen in contact with the first platen until the zone of the first platen attains a first preset temperature and the second platen attains a second preset temperature. 
         [0013]    In another embodiment of the present disclosure, the controller during each preheat mode records a position of the second platen attained as it is stopped by the positioning mechanism as a reference position, and wherein the controller uses the recorded reference position during ensuing cook cycles to recognize a thickness of a food product disposed on the first platen. 
         [0014]    In another embodiment of the present disclosure, the impediment is an object detected between a non-cooking position and a cooking position of the second platen. The controller further responds to the signal by controlling the positioning mechanism to move the second platen away from the first platen to a non-cooking position. 
         [0015]    In another embodiment of the present disclosure, one or more temperature sensors are disposed to sense one or more temperatures at one or more locations of the first platen. The impediment is a food product disposed on the first platen. The controller in a cook cycle uses the sensed temperatures to evaluate an amount of food product on the first platen surface and compensates a cook time of the cook cycle based on the amount of food product. 
         [0016]    In another embodiment of the present disclosure, the controller determines the load sensitivity by evaluating a drop in the temperatures and compensates the cook time based on the drop and a rate of temperature recovery. 
         [0017]    In another embodiment of the present disclosure, a temperature probe is manually disposable at the locations on a surface of the first platen and that is removably connected in circuit with the controller; wherein the controller calibrates surface temperature of the first platen based on temperature probe signals received from the manually disposed surface temperature probes. The locations on the surface preferably bear visible marks. 
         [0018]    The method of the present disclosure controls a clam grill that has first and second platens by moving the second platen toward the first platen, providing a signal in response to a detection of an impediment to the motion of the second platen, and stopping the second platen in response to the signal. 
         [0019]    In another embodiment of the method of the present disclosure, the impediment is the first platen and the signal is provided as the second platen makes contact with the first platen. 
         [0020]    In another embodiment of the method of the present disclosure, in a preheat mode a heater is controlled to apply thermal energy to at least one zone of the first platen and to the second platen. 
         [0021]    In another embodiment of the method of the present disclosure, the second platen is maintained in contact with the first platen until the zone of the first platen attains a first preset temperature and the second platen attains a second preset temperature. 
         [0022]    In another embodiment of the method of the present disclosure, the method comprises the further steps of during each preheat mode recording a position of the second platen attained as it is stopped as a reference position, and using the recorded reference position during ensuing cook cycles to recognize a thickness of a food product disposed on the first platen. 
         [0023]    In another embodiment of the method of the present disclosure, the impediment is an object detected between a non-cooking position and a cooking position of the second platen. The second platen is then moved away from the first platen in response to the signal. 
         [0024]    In another embodiment of the method of the present disclosure, the second platen is moved to a non-cooking position. 
         [0025]    In another embodiment of the method of the present disclosure, the method further comprises the steps of sensing one or more temperatures at one or more locations of the first platen. If the impediment is a food product disposed on the first platen; then the method uses the sensed temperatures to evaluate an amount of food product on the first platen and compensates a cook time of the cook cycle based on the amount of food product. 
         [0026]    In another embodiment of the method of the present disclosure, the method further comprises determining the load sensitivity by evaluating a drop in the temperatures and compensating the cook time based on the drop and a rate of temperature recovery. 
         [0027]    In another embodiment of the method of the present disclosure, the method further comprises sensing one or more temperatures at one or more locations of the first platen, manually disposing a temperature probe at the locations on a surface of the first platen; and calibrating surface temperature of the first platen based on temperature probe signals received from the temperature probe. 
         [0028]    In another embodiment of the method of the present disclosure, the locations on the surface bear visible marks. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Other and further objects, advantages and features of the present disclosure will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and: 
           [0030]      FIG. 1  is a perspective view of one embodiment of a two-surfaced cooking apparatus of the present disclosure; 
           [0031]      FIG. 2  is a side view of the two-surfaced cooking apparatus of  FIG. 1 ; 
           [0032]      FIG. 3  is a rear view of the two-surfaced cooking apparatus of  FIG. 1 ; 
           [0033]      FIG. 4  is a top view of the upper platen assembly of the two-surfaced cooking apparatus of  FIG. 1 ; 
           [0034]      FIG. 5  is a cross-sectional view along line  5  of  FIG. 4 ; 
           [0035]      FIG. 6  is a view of detail B of  FIG. 5 ; 
           [0036]      FIG. 7  is a block diagram of an alternate embodiment of the detector of the two-surfaced cooking apparatus of the present disclosure; 
           [0037]      FIG. 8  is a side view of a portion of the two-surfaced cooking apparatus of  FIG. 1  that depicts another embodiment of the detector; 
           [0038]      FIG. 9  is a side view of a portion of the two-surfaced cooking apparatus of  FIG. 1  that depicts another embodiment of the detector; 
           [0039]      FIG. 10  is a side view of a portion of the two-surfaced cooking apparatus of  FIG. 1  that depicts another embodiment of the detector; 
           [0040]      FIG. 11  is a side view of a portion of the two-surfaced cooking apparatus of  FIG. 1  that depicts another embodiment of the detector; 
           [0041]      FIG. 12  is a block diagram of a preferred embodiment of the controller of the cooking apparatus of  FIG. 1 ; 
           [0042]      FIG. 13  is a flow diagram for the product recognition program of the controller of  FIG. 12 ; 
           [0043]      FIG. 14  is a flow diagram of another embodiment of a program that can be used with the cooking apparatus of  FIG. 1 ; 
           [0044]      FIG. 15  is a flow diagram of a safety program that can be used with the cooking apparatus of  FIG. 1 ; 
           [0045]      FIG. 16  depicts an auto-calibration set up for the cooking apparatus of  FIG. 1 ; and 
           [0046]      FIG. 17  is a flow diagram of a load sensitivity program that can be used with the cooking apparatus of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0047]    It is contemplated that the present disclosure can be used in various styles of two-surfaced cooking apparatus, for example, two-sided contact toasting, clam grills and the like. However, by way of example and completeness of description, the present disclosure will be described herein in a clam grill embodiment. 
         [0048]    Referring to  FIGS. 1-3 , a two-surfaced cooking apparatus  20  of the present disclosure comprises a support structure  22  to which a lower (first) cooking platen  24  is horizontally mounted. Lower platen  24  has a smooth level cooking surface  26  on its upper side. Lower platen  24  is heated to cooking temperature by gas or electric means via heating elements  28  or equivalent gas burners. 
         [0049]    A platen assembly  30  and a platen assembly  31  are movably mounted to the rear of support structure  22  by a positioning mechanism  40  and a positioning mechanism  41 , respectively. As platen assembly  30  and platen assembly  31  are substantially identical, only platen assembly  30  will be described in detail. Platen assembly  30  comprises an upper (second) cooking platen  32  that has a surface  34 . Preferably, surface  34  is heated to cooking temperature by heating elements (not shown) mounted within a casing  36 . Upper platen  32  is either smaller than or equivalently sized to lower cooking platen  24 . A handle  38  mounted on the front side of platen assembly  30  for manual manipulation thereof. Cooking apparatus  20  may have one or more upper platen assemblies. Although two upper platen assemblies are shown, other embodiments may have one or more than two upper platen assemblies. In a preferred embodiment, two or more separate upper platen assemblies are mounted over a single lower platen, allowing for greater flexibility for the cook/operator. Although lower platen  24  is shown as a single platen, it can be two or more platens in alternate embodiments. 
         [0050]    Cooking apparatus  20  further includes a controller  62  (shown in  FIG. 2 ) that is interconnected with heaters  28 , a motor controller  64 , a user interface  68  and one or two activation buttons  60 . Controller  62  controls the cook cycle of cooking apparatus  20  and in so doing controls motor controller  64  and positioning mechanism  40  that imparts motion to platen assembly  30 . User interface  68  includes a display and various user controls. Activation buttons  60  are disposed on the front of cooking apparatus for user control of platen assembly  30 . Activation buttons  61  are disposed on the front of cooking apparatus for user control of platen assembly  31 . 
         [0051]    As positioning mechanism  40  and positioning mechanism  41  are substantially identical, only positioning mechanism  40  will be described in detail. Positioning mechanism  40  facilitates two distinct motions by platen assembly  30  between an uppermost or non-cooking position (see  FIG. 3 ) to a cooking position. In  FIGS. 1-3 , platen assembly  30  is in the non-cooking position and platen assembly  31  is in the cooking position. In this embodiment, positioning mechanism  40  includes a linear actuator  42  that is linked to two vertical reciprocating shafts  44  by an actuator cross bar linkage  46 . Actuator cross bar linkage  46  is clamped to vertical reciprocating shafts  44 , which run through linear motion bearings  48 . Vertical reciprocating shafts  44  are affixed to arm pivot/stop heads  50 . A cantilever beam  52  runs through arm pivot/stop heads  50  through rotational pivot bearings  54 . When platen assembly  30  is in its uppermost rotational position, linear actuator  42  is extended to its maximum position, vertical reciprocating shafts  44  and arm pivot/stop heads  50  are extended upward and to a position which forces the back end of cantilever beam  52  to contact rotational bearings  54 . In this position, platen assembly  30  is at a predetermined angle in a range of about 45 degrees to about 60 degrees from the horizontal. 
         [0052]    Positioning mechanism  40  further comprises a drive motor  56  and position sensor switches  58  ( FIG. 3 ). Drive motor  56  is interconnected with motor controller  64 . A pulse encoder  66  is associated with motor  56  and provides a pulse train to controller  62  when motor  56  is being driven. Position switches  58  are mounted on reciprocating shafts  44  to provide position information to controller  62 . In alternate embodiments, position switches  58  may be eliminated. 
         [0053]    Prior to a cook cycle, platen assembly  30  is in its non-cooking position. In response to user activation of activation buttons  60 , controller  62  initiates a cook cycle by controlling motor controller  64  to drive motor  56  to cause positioning mechanism  40  to move platen assembly  30  from the non-cooking position to a cooking position. For example, platen assembly  31  is shown in the cooking position. 
         [0054]    Positioning mechanism  40  causes platen assembly  30  to descend both vertically and through an arc caused by the cantilever weight of platen assembly  30  maintaining contact between rotational bearings  54  and the back of cantilever beam  52 . When cantilever beam  52  and platen assembly  30  become parallel with lower platen  24 , the stop portion of arm pivot/stop head  50  stops the rotational motion of cantilever beam  52  causing purely vertical motion of platen assembly  30  from this point and further down toward surface  26  of lower platen  24 . When upper platen  32  makes contact with a food product  72 , controller  62  responds by bringing upper platen  32  to an initial cooking position and initiating a cook procedure. During the cook procedure upper platen  32  may be moved based on the requirements of the cook procedure. For example, upper platen  32  may be moved due to changed food product thickness (loss of grease or water) or for applying more or less pressure to the food product at different times during the cook procedure. 
         [0055]    When the cook procedure is completed, controller  62  controls motor controller  64  to drive linear actuator  42  to move platen assembly  30  vertically upward from the cooking position to the non-cooking position. The cantilever weight of upper platen  32  maintains contact between arm pivot/stop head  50  until the back of cantilever beam  52  makes contact with rotational pivot bearing  54 . This movement ensures that platen assembly  30  is constantly parallel to lower platen  24  during this stage of upper platen travel. Once cantilever beam  52  makes contact with rotational pivot bearing  54  the vertical motion is changed to rotational motion to a point where platen assembly  30  is rotated through the predetermined angle to the non-cooking position. Controller  60  causes an audible signal to be sounded (e.g., about two seconds) prior to the start of upward movement of platen assembly  30  to alert the operator of impending upper platen movement. 
         [0056]    The present disclosure provides a detector that provides a trigger signal as upper platen  32  makes contact with food product  72 . Controller  62  responds to the trigger signal to control motor controller  64  to cause positioning mechanism  40  to bring upper platen  32  to the initial cooking position. At this time, controller  62  begins the cooking procedure. The detector is shown herein in several different embodiments. 
         [0057]    Referring to  FIGS. 4-6 , a detector  70  is disposed or attached to cantilever beam  52  of positioning mechanism  40 . When upper platen  32  stops moving because it makes contact with a food product, its motion comes to a stop or continues to move based on the cooking parameters inputted into controller  62 . Positioning mechanism  40  continues to move cantilever beam  52  vertically downward toward casing  36 . Detector  70  senses a small change in the distance between cantilever beam  52  and casing  36  to provide the trigger signal that triggers positioning mechanism  40  to bring upper platen  32  to the initial cooking position. 
         [0058]    Referring to  FIG. 6 , a fastener  74  fastens cantilever beam  52  to casing  36 . Fastener  74  is mounted in cantilever beam  52  in a manner that allows it to float vertically when upper platen  32  is in contact with food product  72 . Thus, when upper platen  32  makes contact with food product  72 , upper platen  32  stops but cantilever beam  52  continues downwardly due to the floating action of fastener  74 . 
         [0059]    In this embodiment, detector  70  is preferably a proximity sensor, for example, model PRX+4400, available from Hermetic Switch Inc. Detector  70  may alternatively be a micro-switch, for example, model E47BM530, available from Eaton/Cutler Hammer. 
         [0060]    Detector  70  may alternatively be a touch sensor including dielectric sensing as well as piezo-electric pressure sensing. For example, the touch sensor may be model T107-A4E-073, available from Piezo Systems, Inc. 
         [0061]    Detector  70  may alternatively be a sonar sensor that is attached to upper platen  32 , lower platen  24  or support structure  22  to detect a sound change due to upper platen  32  contacting the food product. For example, the sonar sensor may be model EFR-RTQB40KS, available from Panasonic. 
         [0062]    Although detector  70  is shown in a specific location, detector  70  can be positioned at any suitable location of cantilever beam  52  that permits detection of upper platen  32  contacting food product  72 . For example, these locations include the front, back, either side, middle or other. In an alternate embodiment, detector  70  may include multiple detectors positioned at different locations. 
         [0063]    Referring to  FIG. 7 , a detector  80  monitors the motor current of drive motor  56 . When upper platen  32  contacts food product  72 , the motor current changes. Detector  80  detects this current change and signals motor controller  64 . Detector  80  can either be separate from motor controller  64  or integral with motor controller  64 . If integral, there is no need for detector  80  to signal motor controller  64 . Detector  80  includes a current sensing resistor  82  (or other circuit for measuring current) connected in the motor current circuit. Detector  80  also includes a current change detection circuit  84  that provides the trigger signal to motor controller  64  when current change detection circuit  84  detects a change in motor current indicative of upper platen  32  making contact with food product  72 . The trigger signal is supplied to controller  62 . 
         [0064]    Referring to  FIG. 8 , a detector  90  comprises a strain sensor attached in a location that detects a change in load after upper platen comes horizontal and when the weight of upper platen  32  is reduced by resting on food product  72 . When detector  90  detects this change in strain, it provides a trigger signal to controller  62 . Controller  62  then controls motor controller  64  to cause positioning mechanism  40  to bring upper platen  32  to the cooking position. Like detector  80 , detector  90  may include a detection circuit (not shown) to detect when a change in the monitored strain signal is indicative of upper platen  32  making contact with food product  72 . 
         [0065]    Referring to  FIG. 9 , a detector  100  includes an optical transmitter  102  and an optical receiver  104  that are positioned to the rear and front, respectively, of cooking apparatus  20 . Optical transmitter  102  provides an optical beam  106  from back to front at a level that will be interrupted by upper platen  32  at about the time it contacts the food product. Optical receiver  104  receives beam  106  and provides a trigger signal when upper platen  32  interrupts beam  106 . Controller  62  uses the trigger signal to bring upper platen  32  to the cooking position. Optical beam  106  may be visible light or invisible, e.g., infrared. 
         [0066]    Referring to  FIG. 10 , alternatively an optical detector  110  is mounted to cantilever beam  52 . Thus, an optical transmitter  112  and an optical receiver  114  are mounted and spaced from one another by a gap such that a light beam emitted by optical transmitter  112  traverses the gap and is received by optical receiver  114 . A shutter  116  is mounted on casing  36 . When upper platen  32  is not in contact with the food product, shutter  116  is outside the gap between optical transmitter  112  and optical receiver  114 . When upper platen  32  slows or stops, it contacts the food product, while cantilever beam  52  continues to move toward casing  36  such that shutter  116  enters the gap and interrupts the light beam. Optical receiver  114  responds by providing a trigger signal to controller  62 . Controller  62  uses the trigger signal to bring upper platen  32  to the cooking position. 
         [0067]    Referring to  FIG. 11 , a detector  120  comprises a plurality of temperature sensors  122  disposed at various locations in upper platen  32 . Temperature sensors  122  provide temperature signals to controller  62 . When the operator starts a cooking cycle, controller  62  monitors the temperature sensor signals. When controller  62 , based on the temperature sensor signals, determines that a given temperature drop in a specified amount of time has occurred, it controls motor controller  64  to cause positioning mechanism  40  to bring upper platen  32  to the cooking position. 
         [0068]    It will be apparent to those skilled in the art that detection circuits can be used in any of the detectors  70 ,  80 ,  90 ,  100 ,  110  and  120  to discriminate the trigger signal from noise. 
         [0069]    Referring to  FIG. 12 , controller  62  includes a processor  130  interconnected by a bus  136  with an input/output (I/O) module  132  and a memory  134 . Memory  134  may be any suitable memory that includes, random access memory (RAM), read only memory (ROM), flash or other memory types or any combination thereof. Processor  130  may be any suitable processor that is capable of running programs that execute cook cycles including cook procedures. I/O module  132 , contains interfaces to each of a plurality of input/output devices, including user interface  68 , pulse encoder  66 , detector  70 ,  80 ,  90 ,  100 ,  110  or  120 , heater elements  28 , motor controller  64  and any other input/output devices included in a cooking apparatus. 
         [0070]    Memory  134  stores a plurality of programs and parameter data including a cook cycle program  140 , a product thickness list  144 , a set of cook procedures  146  and a distance counter  148 . Cook procedures  146  include a set of cook procedures for use by cooking apparatus  20 . For example, cook procedures  146  include a cook procedure for bacon, a cook procedure for a hamburger, a cook procedure for a chicken patty and so on. 
         [0071]    A cook procedure, for example, may simply be a cook time or may also include temperatures for different portions of the cook time, different pressures and/or gap distances for upper platen at different portions of the cook time. 
         [0072]    Cook cycle program  140  includes a product recognition program  142  that recognizes a food product  72  currently on the grill surface  26  of lower platen  24  of  FIGS. 1-6 . This recognition is based on a travel distance of upper platen  32  measured between a reference point to a position at which it makes contact with food product  72 . When cooking apparatus  20  is first started from a cold start, a preheat mode is used before food product  72  can be placed on lower platen  24 . In the preheat mode, platen assembly  30  is lowered until it comes to a stop on lower platen  24  and engages detector  70 . The heaters for lower platen  24  and upper platen  32  are turned on and the platen surfaces are heated to their preset temperatures. This procedure has the advantage of saving energy vis-a-vis a procedure in which lower platen  24  and upper platen are out of contact with one another during the preheat mode. 
         [0073]    After upper platen  32  has been preheated, platen assembly  30  is raised to its upper most non-cooking position to allow the operator to safely place food product  72  on lower platen  24 . As platen assembly  30  begins to rise, cantilever beam  52  reaches the end of the float distance, detector  70  is released from its detected state and generates a trigger signal that controller  62  uses as the reference point. This reference point represents a reference count value, e.g., zero, of surface  26  of lower platen  24 . 
         [0074]    As platen assembly  30  continues to rise, encoder pulses are counted from the reference point to the non-cooking position. Controller  62  records the total count value from the reference point to the upper most non-cooking position, which represents a predetermined reference count value. After food product  72  is placed on lower platen  24 , platen assembly  30  is again lowered. When upper platen  32  contacts food product  72 , detector  70  generates a trigger signal, which controller  62  uses to record the encoder pulse count value at the time of contact with food product  72 . The product thickness is represented by the difference between the pulse count value at the food product contact time and the predetermined reference count value. 
         [0075]    It will be apparent to those skilled in the art that other techniques of measuring the travel distance can be used. For example, the travel distance can be measured by the time that elapses between current triggered count value and the reference point value. The elapsed time, for example, is measured by counting pulses from a timing source, such as a clock. This elapsed time or pulse count is recorded in distance counter  148 . Product recognition program  142  uses distance to recognize a product thickness and uses the recognized product thickness to select a product cook procedure from cook procedures  146  that matches the product thickness. 
         [0076]    The above described procedure of establishing a zero reference value of surface  26  of lower platen  24  provides a self-calibration every time a preheat mode is performed, e.g., upon each power up of cooking apparatus  20 . This is in contrast to systems in which calibration is performed only at time of installation or service. These systems are subject to drift that can affect the calibration. For example, the drift might be due to component wear and/or aging, equipment abuse and/or changes in temperature, barometric pressure and/or humidity. 
         [0077]    Referring to  FIG. 13 , cook cycle program  140  begins at step  170  by starting a cook cycle. Step  170  is performed in response to the operator activating activation button  60 . At step  172  cooking apparatus  20  is initialized. For example, heating elements  28  are turned on and other preliminary operations (not germane to the present disclosure) are performed. Once cooking apparatus  20  is initialized, product recognition program  142  is executed. 
         [0078]    At step  174 , distance counter  148  is initialized to a reference value, e.g., zero. At step  176  motor  56  is started. Processor  130  provides one or more command signals via I/O module  132  to motor controller  64  to provide drive current to motor  56 . This causes positioning mechanism  40  to lower upper platen  32  from its non-cooking position. At step  178 , there is a determination of whether a trigger signal has been received from the detector ( 70 ,  80 ,  110 ,  110  or  120 ). If not, at step  180  it is determined if an encoder pulse has been received. If not, control returns to step  178 . If step  180  determines that an encoder pulse has been received, at step  182  distance counter  148  is incremented. It will be appreciated by those skilled in the art that distance counter  148  could also be decremented from the reference value. Control then returns to step  178  and steps  178 ,  180  and  182  iterate until step  178  detects a trigger signal. 
         [0079]    If step  178  determines that a trigger pulse has arrived, at step  184  a product cook procedure is selected from cook procedures  146  based on the count value of distance counter  148  as of the arrival of the trigger pulse. At step  186  the selected cook program is executed. When step  186  is completed at step  188  upper platen  32  is returned to its non-cooking position. To perform step  188 , processor  130  provides one or more command signals via I/O module  132  to motor controller  64  to provide drive current to motor  56 . This causes positioning mechanism  40  to raise upper platen  32  from its cooking position to its non-cooking position. 
         [0080]    More specifically, step  184  matches the trigger count value of distance counter  148  with count values for different product thicknesses for the food products stored in product thickness list  144 . That is, each count value stored in product thickness list  144  is indicative of a corresponding product thickness of the food product of a corresponding cook procedure. If the trigger count value of distance counter  148  is in-between two of the count values in product thickness list  144 , the count value closest to the trigger count value is used to select a corresponding cook procedure from cook procedures  146 . 
         [0081]    In an alternate embodiment, product thickness list  144  stores a thickness window for the product of each cook procedure. The thickness window is defined by an upper and a lower count value plus or minus a tolerance. The thickness window within which the trigger count value falls is used to select the corresponding cook procedure from cook procedures  146 . If the trigger count value falls between two thickness windows, the closest thickness window is used. For example, the predetermined thickness could be 0.500±0.060 inch. 
         [0082]    During a programming operation, product thickness list  144  and product cook procedures  146  are populated with respective thickness count values and cook procedures for the food products that are to be cooked with food cooking apparatus  20 . The thickness count values and cook procedures can be entered, for example, via a keyboard or other input device (not shown) either via a wired connection or a wireless link. 
         [0083]    Referring to  FIG. 9 , an alternate embodiment of the cook cycle program responds to the trigger signal to execute a cook procedure that is pre-selected by the operator, for example, from user interface  68 . A cook cycle program  200  begins at step  202  by starting a cook cycle. Step  202  is performed in response to the operator activating activation button  60 . At step  204  cooking apparatus  20  is initialized. For example, heating elements  28  are turned on and other preliminary operations (not germane to the present disclosure) are performed. 
         [0084]    At step  206  motor  56  is started. Processor  130  provides one or more command signals via I/O module  132  to motor controller  64  to provide drive current to motor  56 . This causes positioning mechanism  40  to lower upper platen  32  from its non-cooking position. At step  208 , there is a determination of whether a trigger signal has been received from the detector ( 70 ,  80 ,  110 ,  110  or  120 ). If not, then step  208  repeats. If step  208  determines that a trigger signal has been received, then at step  208  the pre-selected cook procedure is executed. When the pre-selected cook procedure has been completed, then at step  212  upper platen  32  is returned to its non-cooking position. Processor  130  provides one or more command signals via I/O module  132  to motor controller  64  to provide drive current to motor  56 . This causes positioning mechanism  40  to raise upper platen  32  from its cooking position to its non-cooking position. 
         [0085]    Referring to  FIG. 15 , a safety feature program  300  is operative during the descent of upper platen  32  from the non-cooking position toward lower platen  24  to return upper platen to the non-cooking position should an obstruction or impediment be detected as upper platen  32  descends. The obstruction, for example, might be a body part of the operator, such as an arm or a hand, or a physical object other than food product  72 , such as a pot, pan or other object. The presence of the objection is determined by controller  62  based on an input or trigger signal from detector  70 . 
         [0086]    When a cooking process is initiated, upper platen  32  moves downward toward lower platen  24 . If at any time between the uppermost or non-cooking position and a predetermined distance above cooking surface  26 , controller  62  receives a trigger signal from a detector, controller  62  stops upper platen  32 , reverses its direction of motion and returns it to the uppermost position. The predetermined distance is greater than the food products being cooked. For example, the predetermined distance in one embodiment was set at 1.375 inch. The detector, for example, can be any of the detectors  70 ,  80 ,  90 ,  100  or any other suitable detector. For the purpose of the following description, the detector is assumed to be detector  70 . 
         [0087]    Safety feature program  300  is executed by controller  62  and at step  302  determines if a cooking process is being performed. If no, program  300  waits for a cooking process to start. If yes, at step  304 , controller  62  determines if there is a trigger signal from detector  70 . If no, steps  302  and  304  are repeated until a trigger signal is determined by step  304 . If yes, at step  306  controller  62  determines if the current count is greater than a predetermined value that represents the predetermined distance above cooking surface  26 . That is, the trigger signal has occurred above food product  72  and, therefore, was generated by an obstruction. If yes, controller  62  at step  308  stops the downward travel of upper platen  32  and moves it upward until it is returned to the uppermost position. 
         [0088]    Should step  306  determine that the current count value is not greater than the predetermined value, controller  62  proceeds to perform the cook process at step  310 . At step  312 , controller  62  returns upper platen  32  to its uppermost position when the cook process is finished. 
         [0089]    Referring to  FIG. 16 , a zone of lower platen  24  comprises a mark X that denotes the location of a temperature probe  320  affixed to or inserted in a probe receptacle of a lower surface  27  of platen  24 . Temperature probe  320  is connected to controller  62  via an electrical connection  322 . 
         [0090]    A feature of the present disclosure provides for automatic temperature calibration of surface  24  without having a person manually input the temperature values. Controller  62  is provided with a temperature calibration mode that is selectable, for example, by an operator using user interface  68 . When the temperature calibration mode is selected, the operator places a temperature probe  326  near or in the vicinity of (e.g., over) the mark X that corresponds to the location of temperature probe  320 . Although only one temperature probe  320  is shown, it should be apparent to those skilled in the art that one or more temperature probes  320  can be deployed at various locations of lower platen  24 . Each such temperature probe  320  would be identified by a corresponding visible mark X. 
         [0091]    The operator also plugs into controller  62  an electrical connection  324  that is connected to temperature probe  326 . Controller  62  compares temperature values of surface  26  sensed by temperature probe  326  to temperature values received from temperature probes  320  and matches the value from the remote temperature probe  326  automatically calibrating temperature probes  320  without any manual inputs of temperature values into user interface  68 . For example, controller  62  compares the temperatures sensed by temperature probe  326  with the temperatures sensed by corresponding temperature probes  320 . Controller  62  uses the difference between the two temperatures as an offset value to determine surface temperature based on actual sensed temperature by temperature probe  320 . 
         [0092]    The present disclosure also comprises a load sensitivity feature that enables controller  62  to evaluate a temperature profile of a cooking cycle and, from this profile, determine the amount of food product  72  being cooked, and adjusting cooking time based on the amount of food product  72  on the grill surface  26 . In one embodiment. The load sensitivity is rated in three categories, namely, a light load that requires a minimum cook time, a medium load that requires a nominal time, and a full load that requires a maximum time. As an example, the operator places one food product (e.g., a hamburger patty)  72  on lower grill surface  26  and initiates a cooking cycle by pressing a corresponding activation button  60  or  61 . Upper platen  32  lowers until it contacts food product  72 . When food product  72  is contacted, upper platen  32  stops and the lift mechanism continues downward slightly tripping a switch (detector  70 ,  80 ,  110  or  120 ) indicating upper platen  32  has stopped on food product  72 . Controller  62  then determines the food product thickness and initiates a cooking cycle timer based on the product thickness. As food product  72  is being cooked the temperatures of surface  26  of the grill platen  24  and the surface  34  of upper platen  32  will drop due to the food product being colder than surfaces  26  and  34 . As the surface temperatures drop, controller  62  monitors the temperature drop and recovery rate over time of surfaces  26  and/or  34  during the cooking process. Just prior to end of the cooking cycle, controller  62  determines the rate and amount of surface(s) temperature drop and rate of recovery. Using this data, controller  62  determines that there is a light load on the grill and shortens the cook time slightly so that food product  72  is not over cooked. 
         [0093]    If the operator had placed the maximum amount of food products  72  on the grill surface and started a cooking cycle, the “temperature curve” of the grilling surfaces would drop further and recover at a slower rate. Near the end of the cooking cycle, controller  62  would evaluate this data, and extend the cooking time to compensate for the reduced thermal input to the full load of food products  72 . 
         [0094]    If a number of food products greater than one and less than a full load are placed on lower grill surface  26  and a cooking cycle is initiated, controller  62  will monitor a “temperature curve” for temperature drop and recovery rate. 
         [0095]    Referring to  FIG. 17 , a load sensitivity program  350  is executed by controller  62 . At step  352 , a cook cycle timer is initiated based on thickness of the food product to a default or nominal time for the recognized food product. At step  354 , controller  62  runs the cook process for the food product. At step  356 , controller  62  determines if the current cook cycle timer value is equal to a predetermined load determination time. This predetermined time is preferably near the end of the default time. If no, steps  354  and  356  repeat until step  356  determines that the current cycle timer value equals the predetermined load determination time. If yes, at step  358 , controller  62  determines a load sensitivity (light, heavy or in between) based on temperature drop and rate of recovery of surfaces  26  and/or  34  of lower and upper platens  24  and  32 . If light, the default time is reset to a predetermined minimum time at step  360 . If heavy, the default timer is reset to a maximum predetermined time at step  362 . If in between, the default time is maintained at step  364 . The predetermined minimum and maximum times can be determined by running cook cycles for the food products and recording cook cycle times for light, heavy and in between loads. 
         [0096]    It will be apparent to those skilled in the art that the assignment of the default or nominal time to the in between time is a matter of choice and could alternatively be assigned to either the light or heavy load sensitivities with adjustments to the program procedure. Also, the load sensitivities could be rated in more or less than three categories if desired. 
         [0097]    The present disclosure having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present disclosure as defined in the appended claims.