Abstract:
A rotisserie system includes a rotatable skewer adapted to secure meat, the rotatable skewer including a temperature sensor for recording a temperature of the meat and a wireless transmitter for wirelessly transmitting the temperature. The system also includes a remote temperature monitor having a wireless receiver for receiving the wirelessly transmitted temperature and a visual display for displaying the temperature, whereby the remote temperature monitor is movable away from the rotatable skewer while remaining in wireless communication with the wireless transmitter to enable an operator to continuously monitor the cooking temperature of the meat. The wireless transmission and reception may be accomplished using infrared light or radio frequency waves.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is generally directed to cooking and is particularly directed to rotisserie cooking systems. 
     A rotisserie is a cooking device having a rotating spit on which meat is skewered and then continuously rotated during cooking. One of the long-standing problems with rotisseries has been an inability to obtain accurate temperature readings for the meat being roasted. This is due, in part, to the fact that the meat must be continuously rotated during cooking. The constant motion makes it difficult to obtain a temperature reading. In response to this problem, there have been a number of efforts directed to obtaining temperature readings for rotisserie-cooked foods. 
     U.S. Pat. No. 3,511,167 to Holtkamp discloses a cooking oven having a rotisserie spit with a temperature probe provided for insertion into meat and a cable connecting the probe to a temperature responsive device in a wall of an oven. The direct connection by cable between the meat on the rotisserie spit and a fixed receptacle in the wall of the oven precludes continuous rotation of the spit and the meat skewered on the spit. Holtkamp provides a mechanism between a rotisserie spit motor and the spit itself that converts the rotary motion of the motor into oscillating motion of the spit. The spit oscillates through an arc of about 100° to 540°, making it possible to use a meat probe connected to an oven receptacle by a cable of limited length. 
     U.S. Pat. No. 4,075,454 to Henyan discloses a thermometer support for a rotisserie whereby a thermometer is insertable into a body of meat or other food disposed on a spit. The rotisserie has a bracket with an upstanding tongue provided with an aperture adapted to receive a portion of the thermometer. 
     U.S. Pat. No. 2,898,845 to Dight discloses a combination skewer and thermometer designed to adequately support a roast in a desirably revolving arrangement, and at the same time, has a centrally disposed heat-sensing device, such as a metallic thermometer. The heat-sensing device may be placed at the center of the roast for obtaining internal temperature readings for the roast. 
     U.S. Pat. No. 2,787,948 to Mathis discloses a rotary spit thermometer having a built-in device for indicating when meat has been cooked to a desired temperature. The rotary spit assembly includes a hollow shaft insertable through the center of a piece of meat, with a temperature sensitive element arranged in the interior of the shaft. The rotary spit shaft may be driven by an electric gear motor placed at the rear of an oven. 
     One problem with the prior art advances described above is that an operator must remain close to the oven or barbecue grill used to cook the meat. As a result, an operator is not free to move away from the cooking location while maintaining continuous temperature monitoring of the item being cooked. This is particularly important for gourmet cooking where cooking to exacting temperatures is highly desirable. Another problem with the prior art is that an operator must frequently open the oven or barbecue grill to obtain the latest temperature readings, which may abruptly change the temperature inside the oven or grill. Rapid temperature changes may adversely affect the cooking operation. 
     SUMMARY OF THE INVENTION 
     In accordance with certain preferred embodiments of the present invention, a rotisserie system includes a rotatable spit adapted to secure meat, the rotatable spit including a temperature sensor for recording a temperature of the meat and a wireless transmitter for wirelessly transmitting the recorded temperature. The rotisserie system also preferably includes a remote temperature monitor including a wireless receiver for receiving the wirelessly transmitted temperature and a visual display for displaying the temperature, whereby the remote temperature monitor is movable away from the rotatable spit while remaining in wireless communication with the wireless transmitter of the spit. The wireless transmitter is preferably an infrared transmitter or a radio frequency transmitter and the wireless receiver is preferably an infrared receiver or a radio frequency receiver. 
     In certain preferred embodiments, the rotatable spit has a pointed end for skewering meat, a handle end and a shaft extending between the pointed end and the handle end. The rotatable spit also preferably includes one or more electrical contacts accessible at an outer surface of the shaft. The rotisserie system also preferably includes a sensor ring securable over the spit shaft, the sensor ring includes a contact plate engagable with the one or more contacts of the spit shaft for forming an electrical interconnection between the sensor ring and the spit shaft. The sensor ring also preferably includes two or more hollow fork fingers, whereby one of the two or more hollow fork fingers includes a temperature sensor such as a thermistor. In certain preferred embodiments the sensor ring may have four fork fingers that are the rotisserie system may also include a conductive line having a first end connected to the temperature sensor and a second end connected to the contact plate of the sensor ring. 
     In certain preferred embodiments, the one or more contacts accessible at the outer surface of the spit shaft include a plurality of contacts. In other preferred embodiments, the plurality of space contacts are evenly spaced from one another along the spit shaft. The sensor ring can be placed anywhere along the length of the shaft as long as the sensor ring is in electrical contact with one of the spaced contacts. 
     The sensor ring may also include a rotatable locking screw adapted for locking the sensor ring in place at a selected location along the length of the spit shaft. When tightened, the locking screw preferably precludes rotary and lateral movement of the sensor ring relative to the spit shaft. 
     The remote temperature monitoring unit preferably includes data entry keys for selecting one of a plurality of meats for temperature monitoring and a visual display for displaying cooking information related to the temperature readings received by the wireless receiver. The remote temperature monitor may also include a memory for storing cooking data related to the plurality of meats and doneness temperature ranges associated with each of the plurality of meats. The doneness temperature ranges may include temperature ranges for well, medium, medium rare and rare doneness levels. Subroutines for selecting meats and doneness levels for the meats are disclosed in commonly assigned U.S. patent application Ser. No. 09/563,813, filed May 3, 2000, the disclosure of which is hereby incorporated by reference herein. 
     In other preferred embodiments of the present invention, a rotisserie system includes a rotatable spit having a shaft with an outer surface and a plurality of spaced contact pads accessible at the outer surface of the shaft. The rotisserie system also preferably includes a sensor ring including two or more fork fingers projecting therefrom, a temperature sensor in one of the fork fingers, and a contact plate in communication with the temperature sensor, wherein the sensor ring is securable on the shaft in engagement with one of the contact pads so that the contact plate of the sensor ring is in electrical contact with one of the contact pads. 
     These and other preferred embodiments of the present invention will be described in more detail below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a rotisserie system having a remote temperature monitor, in accordance with certain preferred embodiments of the present invention. 
     FIG. 2 shows a perspective view of a rotatable spit and sensor ring of the rotisserie system of FIG.  1 . 
     FIG. 3 shows the sensor ring and spit of FIG. 2 partially assembled together. 
     FIG. 4 shows the sensor ring and spit of FIG. 2 during a further assembly step. 
     FIG. 5 shows an exploded view of the sensor ring and a partial cross-sectional view of the rotatable spit of FIG. 2, in accordance with certain preferred embodiments of the present invention. 
     FIGS. 6A and 6B show perspective views of a remote temperature monitor for a rotisserie system, in accordance with certain preferred embodiments of the present invention. 
     FIGS. 7A and 7B show respective left and right side views of the remote temperature monitor of FIGS. 6A and 6B. 
     FIG. 8 shows a front elevational view of the remote temperature monitor of FIG. 6A, including a display screen. 
     FIG. 9 shows a top view of the remote temperature monitor of FIG.  6 A. 
     FIG. 10 shows the display screen of the remote temperature monitor of FIG. 8, in accordance with certain preferred embodiments of the present invention. 
     FIG. 11 shows a fragmentary view of the rotisserie system of FIG. 1 including a handle having an infrared light and a remote temperature monitor having an infrared sensor. 
     FIG. 12 shows a schematic diagram of the handle and remote temperature monitor of FIG.  11 . 
     FIG. 13 shows a fragmentary view of the rotisserie system of FIG. 1 including a handle and a remote temperature monitor having an RF receiver. 
     FIG. 14 shows a schematic diagram of the handle and remote temperature monitor of FIG.  13 . 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a rotisserie system  20  of the present invention including a rotatable spit  22  with one or more sensor rings  24  attached thereto. Each sensor ring  24  has one or more fork fingers  26  projecting therefrom. The rotisserie system  20  also includes a handle  28  having one or more control buttons thereon and a remote temperature monitor  30  that is in signal-receiving communication with handle  28 . As will be described in more detail below, during a cooking operation, temperatures obtained by one of the fork fingers  26  are transmitted by conductive lines through spit  22  to handle  28 . The temperature reading is then wirelessly transmitted from handle  28  to remote temperature monitor  30 . The wireless transmission preferably occurs through either infrared signals or radio frequency. 
     FIG. 2 shows rotatable spit  22  before sensor ring  24  is secured thereto. Rotatable spit  22  includes a pointed end  32 , a handle end  34  and a shaft  36  that extends between the pointed end  32  and the handle end  34 . A series of contacts  38   a ,  38   b  and  38   c  are spaced along the length of shaft  36  between pointed end  32  and handle end  34 . The contacts  38   a-c  are preferably evenly spaced from one another. In preferred embodiments, the rotatable spit  22  is made of heat conductive materials, such as metal. 
     The sensor ring  24  preferably includes a central opening  40  defined by annular wall  42 . The central opening also includes a key slot  44  adapted to receive one of the spit contacts  38   a - 38   c . The sensor ring  24  also includes a plurality of hollow fork fingers  26   a - 26   d . At least one of the hollow fork fingers  26   a - 26   d  preferably includes a temperature probe such as a thermistor (not shown). The sensor ring  24  also includes a locking screw  46  for locking the sensor ring to the rotating spit. The locking screw  46  preferably includes a distal end  48  that may be screwed into aperture  40  for locking the sensor ring in a stationary position relative to spit shaft  36 . 
     Referring to FIGS. 2 and 3, sensor ring  24  is assembled with spit  22  by passing pointed end  32  of spit  22  through sensor ring aperture  40 . The sensor ring  24  may be secured at a plurality of positions along the length of spit shaft  36 . In certain preferred embodiments, the sensor ring  24  may be secured to the spit shaft  36  in engagement with one of the three contacts  38   a ,  38   b  or  38   c.    
     Referring to FIG. 4, in one preferred embodiment, sensor ring  24  is moved toward handle end  34  of shaft  36  until key slot  44  is aligned with third sensor  38   c . The sensor ring  24  is then rotated in a counterclockwise direction designated by arrow “A” until the third sensor  38   c  contacts the annular wall (not shown) surrounding aperture  40 . The engagement of the sensor  38   c  with the annular wall of sensor ring  24  creates an electrical connection between contact  38   c  and sensor ring  24  so that temperature signals may pass between sensor ring  24  and spit  22 . Once the sensor ring  24  is in electrical communication with third contact  38   c , the locking screw  46  is rotated in a direction indicated by arrow “B” for preventing further movement of the sensor ring  24  relative to spit shaft  36 . 
     FIG. 5 shows a partially exploded view of the sensor ring  24  shown in FIGS. 2-4 and a partial cross-sectional view of spit  22 . Spit  22  includes sensor  38   c  having a pair of lower contacts  52   a ,  52   b , a ceramic insulator  54  and a S.S. container  56 . A pair of conductive wires  58  are connected to the lower contacts  52   a ,  52   b . The conductive wires  58  pass through an opening  60  at the handle end  34  of spit shaft  36 . The conductive wires  58  carry temperature signals to the handle (not shown). 
     The sensor ring  24  includes a cover  62  that is assembled with a main body  64 . Sandwiched between cover  62  and main body  64  are ceramic insulators  66 ,  68  that are assembled together. A first contact plate  70  is secured to first ceramic insulator  66  and a second contact plate  72  is secured in recess  74  of second ceramic insulator  68 . When the sensor ring  24  is secured to skewer shaft  36 , the first and second contact plates  70 ,  72  engage lower contacts  52   a ,  52   b  for creating an electrical connection between sensor ring  24  and conductive lines  58 . 
     The sensor ring  24  also includes temperature transmitting lines  75   a ,  75   b  having first ends  76   a ,  76   b  attached to the respective contact plates  70 ,  72  and second ends  78   a ,  78   b  connected to thermistor  80 . The thermistor  80  is disposed within one of the hollow fork fingers  26 . The open end  82  of fork finger  26  is closed by pointed cap  84 . In operation, temperature readings obtained by thermistor  80  are passed through temperature communication line  75   a ,  75   b  to contact plates  70 ,  72 . The temperature signals are then transmitted to contacts  52   a ,  52   b  and onto communication lines  58 . The communication lines  58  carry the temperature signals to handle (not shown) which includes internal electronic circuitry for receiving the temperature signals and wirelessly transmitting the temperature signals to a remote temperature monitor. 
     FIGS. 6A and 6B show a remote temperature monitor  30  including a front face  86 , one or more data entry keys  88 , a speaker  90  for emitting sound, and an adjustable stand  92  adapted for holding the remote temperature monitor  30  in upright orientation. 
     FIGS. 7A and 7B show respective left and right side views of the remote temperature monitor  30 . Stand  92  includes an upper end  94  hingedly secured to a rear portion  96  of remote temperature monitor  30 . The stand  92  may be swung back and forth in the directions indicated by arrow “C” to move the stand between a closed position and an open position shown in FIGS. 7A and 7B. 
     Referring to FIG. 8, remote temperature monitor  30  includes a display screen  98  for displaying cooking information, as will be described in more detail below. 
     FIG. 9 shows a top view of remote temperature monitor  30  including hingedly connected stand  92  in the open position for holding the remote temperature monitor in an upright position. 
     FIG. 10 shows the visual display  98  of the remote temperature monitor, in accordance with certain preferred embodiments of the present invention. Visual display  98  preferably includes food select indicators  100  that show the particular meat selected for temperature monitoring, such as indicators for beef, pork and poultry. Doneness indicators are provided under each of the selected food indicators. In preferred embodiments, each food has a “well done” indicator  102 , a “medium” indicator  104 , a “medium rare” indicator  106  and “rare” indicator  108 . The visual display  98  also includes a temperature display  110  capable of displaying temperature readings in either Fahrenheit or Celsius, a low battery indicator  112  for the rotatable spit  22 , and a low battery indicator  114  for the remote temperature monitor  30 . The visual display  98  also preferably includes a set indicator  116  for indicating whether a final desired cooking temperature has been selected and a taste indicator for indicating whether a taste preference has been selected (e.g. well done). 
     FIG. 11 shows the rotisserie system  20  of the present invention including handle  28  and remote temperature monitor  30 . Handle  28  includes an “on-off” button  120  for activating the spit portion of the system. The handle also includes a power indicator light  122  for indicating that the system is “on,” as well as an infrared light  124 . The temperature readings obtained by the temperature sensor at one of hollow fork fingers (not shown) are transmitted through spit shaft  36  to handle  28 . The temperature signals are then transformed into infrared signals that are transmitted by infrared light  124  to infrared sensor  126  on remote temperature monitor  30 . 
     FIG. 12 shows a schematic diagram of the handle  28  and the remote temperature monitor  30 . The handle  28  includes microprocessor  128  that obtains temperature signals through line  58 . The temperature signals are then transformed at microprocessor  128  to generate infrared signals emitted from infrared light  124 . The infrared signals pass through space  130  between handle  28  and remote temperature monitor  30 . The remote temperature monitor  30  includes infrared sensor  126  in communication with second microprocessor  132 . The second microprocessor  132  is preferably in communication with display screen (not shown) and noise generating element  134 . Microprocessor  132  is also in communication with memory  136  that stores temperature range data for various types of meat as well as doneness data for the various types of meat. For example, the memory may store temperature cooking data for various types of meat such as beef, pork and poultry. The memory may also store temperature ranges for specific taste preference doneness levels for each of the types of meat. Specifically, the memory device  136  may include temperature ranges for cooking beef to rare, medium rare, medium and well done doneness levels. 
     Referring to FIGS. 11 and 12, in operation, a user will skewer one or more pieces of meat on spit shaft  136 . The spit will preferably be placed in an oven, barbecue grill or other cooking instrument for cooking the meat. As the spit shaft rotates, temperature readings obtained through hollow fork fingers are transmitted from the sensor ring to the contact on the shaft, and then through shaft  36  to handle  28 . In handle  28 , the temperature readings are transformed by microprocessor  128  into infrared signals that are transmitted from infrared light  124  to infrared sensor  126 . The infrared signals obtained by infrared sensor  126  are transmitted to second microprocessor  132 . Depending upon the type of meat and taste preference selected, and the information obtained from memory device  136 , the microprocessor will activate the various display indicators on visual panel  98 . The microprocessor may also send a signal to noise generating unit  134  to generate an audible signal such as a beep or alarm. 
     FIGS. 13 and 14 show another embodiment of the present invention whereby the temperature signals are transmitted between the handle  1028  and the remote temperature monitoring unit  1030  by radio frequency (RF) waves. In this particular embodiment, spit  1020  includes shaft  1036  having handle  1028 . The handle  1028  includes an “on-off” switch  1120 . The “on-off” switch may be depressed for activating or deactivating the spit  1020 . Upon obtaining temperature readings, the temperature readings are transmitted via radio frequency between handle  1020  and remote temperature monitor  1030 . FIG. 14 shows a schematic diagram of the handle  1028  and remote temperature monitor  1030  of FIG.  13 . Handle  1028  includes microprocessor  1128  connected with temperature communication line  1058 . As described above, temperature readings obtained by one of the hollow fork fingers of sensor ring (not shown) are transmitted through temperature communication line  1058  to first microprocessor  1128 . The temperature signals are then transmitted to radio frequency transmitter  1124  which wirelessly transmits the temperature signals to radio frequency receiver  1126  of remote temperature monitor  1030 . The temperature readings obtained at radio frequency receiver  1126  are transmitted to second microprocessor  1132 . The second microprocessor  1132  compares the temperature readings to the various temperature ranges stored in memory device  1136 . Depending upon the particular type of meat selected, the microprocessor will obtain the doneness levels for the particular type of meat. If an appropriate doneness level has been attained, the microprocessor  1132  will generate signals for display on visual display  1098  and/or noise generating unit  1134  for generating an alarm signal or beep. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.