Patent Grant
8723086
The present disclosure relates to food warming systems and more particularly, to an improved, heat lamp system suitable for home-use.
When serving certain foods in a home environment, it is desirable to maintain an appropriate temperature of the food to maintain the palatability of the food and to prevent the development of unsafe biological conditions. Specifically, if certain foods are maintained at temperatures between about 40° F. and about 140° F. for several hours, consumption of that food may present a high risk of food borne illness. In certain situations, prepared foods will be set out for a number of hours in order to stage a large or complex meal or allow people to eat when they are ready.
A number of solutions exist for home use, but each has disadvantages. Some of these solutions are electric warming plates, electric warming drawers, and hot water baths heated by self-contained alcohol burners. In commercial environments, heat lamps are frequently used for this purpose, but commercial heat lamps are generally incompatible with a residential environment because of size, weight, lack of adjustability, non-portability and other factors.
The incompatibility of heat lamp systems with certain residential environments is solved by the systems and methods disclosed here. Further, the presently disclosed system may serve additional needs, such as providing a safe and rapid system for dehydrating foods. Additional and further benefits may result by employing the presently disclosed systems.
Certain embodiments of the present disclosure provide a heating device of a portable nature. According to one aspect of the invention, there is provided a heating device of a portable nature comprising: a heating element; a hinge coupled to the heating element; and an arm coupled to the hinge.
According to still another aspect of the invention, there is provided a heating device of a portable nature comprising: an emitter of electromagnetic energy; a reflective shield at least partially surrounding the emitter; an external shade at least partially surrounding the reflective shield, the external shade having an air vent; and an air space between the reflective shield and the external shade, whereby convective air is allowed to flow around the heating device, through the air space, and through the air vent.
Another aspect of the invention provides a heating device of a portable nature comprising: a base; a lamp assembly including: an emitter of electromagnetic energy aimed towards a target, a reflective shield at least partially surrounding the emitter and reflecting at least a portion of the electromagnetic energy towards the target, an external shade made from a first thermally insulating material, and a chimney thermally insulated relative to the reflective shield and coupled to at least one of the emitter, the reflective shield and the external shade; and a support arm mechanically connected to the base and the lamp assembly, wherein the support arm movably supports the lamp assembly.
Still further aspects of the invention provide a heating device of a portable nature comprising: a base; a lamp assembly comprising: a means for generating infrared radiation, a means for reflecting infrared radiation toward an intended target, a means for safely channeling high temperature convective air flows through the lamp assembly, and a means for externally shading and insulating the lamp; and a support arm mechanically connected to the base and the lamp assembly, wherein the support arm moveably supports the lamp.
While the term “infrared” is used to describe the energy emitted from the heating devices of the present invention, it should be understood that different embodiments of the invention will emit a much broader electromagnetic spectrum than infrared. In particular, far-infrared, mid-infrared and near-infrared may be used. Further, while emitters of the present invention may primarily emit infrared energy, other wavelengths may also be emitted simultaneously, such as for example, ultraviolet light, visible radiation (light), terahertz radiation, and microwaves. While the term “infrared” is used to describe the energy emitted, it should be understood that this term is intended to broadly include any of the noted wavelengths as well as any combination of the noted wavelengths.
A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:
a and 3b provide two views of the support arm knuckle assembly from a head-on angle and a side view angle, according to certain embodiments of the present invention:
a and 7b illustrate two slightly different views of chimney 113, according to certain embodiments of the present invention;
a and 9b provide two views of a heat lamp, according to certain embodiments of the present invention: and
A more complete and thorough understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features. Preferred embodiments and their advantages over the prior art are best understood by reference to
Lamp 110, or head assembly, further includes handle 111, outer shade 112, chimney 113, and grille 114. Handle 111 may be a looped structure suitable for gripping to reposition lamp 110 or to redirect the energy produced by lamp 110. For example, two heat lamps 100 may be used together to heat a large turkey or roast wherein each heat lamp 100 is positioned above and to each side of the item. Handle 111 may be used to angle each lamp 110 towards the item. Handle 111 may be made from a thermally non-conductive material to prevent transfer of heat from the hot portions of lamp 110 to handle 111. In some embodiments, handle 111 is mounted directly to outer shade 112, and is therefore not subjected to significant temperatures.
Outer shade 112 provides a safe, low-temperature external surface for lamp 110 in order to prevent burns or damage that would result from a person or non-heat safe material coming into contact with the high temperature elements of lamp 110. Outer shade 112 may also provide a level of impact resistance to prevent damage to the internal components of lamp 110 should heat lamp 100 tip over or fall during handling. Outer shade 112 may be made from a suitable non-conductive and sturdy material with a high melting point and sufficient rigidity to hold together the components of lamp 110. In certain embodiments, outer shade 112 may incorporate a high-temperature plastic (e.g., polyphenylene sulfide). In certain embodiments, outer shade 112 incorporate metallic material, e.g., cold rolled steel, especially where a low output or highly efficient infrared emitter is utilized. In some embodiments outer shade 112 may be lined with a thermally insulating material.
Chimney 113 forms a pathway for heated air to escape, thus allowing convective airflow to cool the internal structures of lamp 110. Chimney 113 may also provide structural support for internal components (as illustrated in
Grille 114 maintains a physical separation of internal, high-temperature components of lamp 110 and external elements like hands, surfaces, and food items. Grille 114 may provide protection of fragile internal components from impact with hard objects and from contact with moist foods, which could cause rapid cooling of the internal heating element. Grille 114 may be a wire mesh and may extend past the edge of outer shade 112. Grille 114 may be constructed from a thin wire or reflective wire to reduce wasteful absorption or scattering of infrared energy produced by lamp 110. Grille 114 may be made from a clear material similar to the lens in a halogen light fixture. Alternatively, for embodiments of the invention that use a bulb as the heating element, a grill may or may not be omitted.
Support arm 120 further includes upper lamp pivot 121, elbow 122, lower lamp pivot 123, and arm members 124. Support arm 120 provides separation between lamp 110 and base 130. This separation may be fixed, binary (e.g., either stored or deployed), or variable. Support arm 120 may be interchangeable to allow for different separations. Support arm 120 may be detachable for shipment or storage. More than one support arm may be provided with base 130, each supporting the same or different lamp 110.
Upper lamp pivot 121 may be a hinge or ball joint that allows a user to adjust the angle of lamp 110 relative to the countertop or food item. Upper lamp pivot 121 may be a hinge with some freedom to rotate about the lengthwise axis of arm member 124. Upper lamp pivot 121 may include a channel housing two or more electrical wires, which provide power to lamp 110. This channel may be enclosed. Upper lamp pivot 121 may incorporate one or more friction elements (c.a., friction washers or pads) to allow lamp 110 to maintain a set orientation after the user makes an orientation adjustment. Upper lamp pivot may include tabs and key slots (as illustrated in
Elbow 122 may be a hinge or ball joint that allows a user to adjust the flex of support arm 120, which allows extension of arm 120. In some embodiments, elbow 122 allows for variable adjustment of the separation of lamp 110 from a surface or food item and may include friction elements to allow elbow 122 to maintain a particular separation set by a user. Elbow 122 may include a channel housing two or more electrical wires, which provide power to lamp 110.
Lower lamp pivot 123 may be a hinge or ball joint that allows a user to adjust the angle of support arm 120 relative to base 130. Lower lamp pivot 123 may be a hinge with some freedom to rotate about the lengthwise axis of arm member 124. Lower lamp pivot 123 may include a channel housing two or more electrical wires, which provide power to lamp 110. This channel may be enclosed. Lower lamp pivot 123 may incorporate one or more friction elements (e.g., friction washers or pads) to allow support arm 120 to maintain a set orientation after the user makes an orientation adjustment. Lower lamp pivot 123 may also incorporate locking recess 134. Lower lamp pivot 123 may also incorporate a power disconnect switch 135 (e.g., a micro switch) that may be engaged by a tab on one portion of the pivot such that when the angle of lower lamp pivot passes a threshold (e.g., 30° from vertical), the switch disconnects power to the infrared emitter. This pivot switch prevents the heat lamp from being energized in a stowed position.
Arm members 124 provide support for lamp 110. Arm members 124 may be hollow tubes (e.g., round or square) providing a channel for at least two electrical wires (a hot and a neutral), which provide power to lamp 110. Arm members may be made from a light, stiff material like aluminum. Arm members 124 may have a fixed length or may include nested members to enable telescopic extension.
Base 130 may be a clamp or other attachment to a countertop or other existing surface. Base 130 may incorporate weights or heavy materials to provide stability and tip-over protection. Base 130 further includes power control 131, over-current protector 132, tip-over switch 133, and locking recess 134. Power control 131 allows a user to activate or deactivate lamp 110. Power control 131 may be an electromechanical switch or may be a microprocessor controlled switch with a user input mechanism. Power control 131 may include input for selecting from a fixed or continuous range of output levels. In some embodiments, power control 131 is a simple on/off switch. In other embodiments, power control 131 is a multiple position switch, for example, with settings for off low output, and high output. In still other embodiments, power control 131 allows a user to set an output intensity or a target food temperature, selected from a range of intensities or temperatures. In some embodiments, power control 131 includes a timer mechanism for automatically shutting off power to lamp 110 after a specified duration of time, e.g., a specified number of hours. In some embodiments, power control 131 incorporates a proximity sensor. In certain embodiments, the proximity sensor may temporarily turn off power to lamp 110 while a user has his hands under lamp 110, for example to serve himself some food. In certain embodiments, the proximity sensor may turn off power to lamp 110 after a predetermined amount of time has passed since a user has been in proximity to the heat lamp, e.g., the proximity sensor attempts to sense that the party is over.
Over-current protector 132 detects an interrupts an excessive current situation. Over-current protector 132 may be a single-use fuse, resettable fuse, or a circuit breaker. Tip-over switch 133 detects a dangerous tip-over condition (e.g., tip-over past a predetermined threshold) and disconnects power to lamp 110 to prevent a possible fire hazard. Tip-over switch may be a mercury switch, a ball contact switch, or other design. Tip-over switch may be calibrated to open when base 130 is tilted more than approximately 30°. Tip-over switch 133 may be a spring-loaded, plunger actuated switch mounted on the underside of base 130. When base 130 is flush with a countertop, the plunger is forced into a recess, which closes the switch. When base 130 tips over or is lifted from the countertop, the plunger will extend, thus opening the switch.
Temperature may also be controlled through the use of a remote temperature monitor that is placed proximate the food or target so as to more accurately monitor the temperature of the food or target. A temperature control may then be set to turn on and/or control the intensity of the infrared emitter when the remote temperature monitor senses a temperature below a threshold that may be set by the operator. The remote temperature monitor may comprise a probe or any other device known for this purpose.
Locking recess 134 provides a channel for accepting and retaining arm member 124, e.g., for storage or shipment. Locking recess 134 may incorporate a spring-loaded locking mechanism to retain arm member 124. In some embodiments, a retaining strap is provided to hold arm member 124 securely in locking recess 134. In some embodiments, a power disconnect switch is incorporated into locking recess 134 to automatically disconnect power when the heat lamp is stowed.
Infrared emitter 201 converts electrical energy to infrared radiation. In some embodiments, infrared emitter 201 is designed to generate far infrared radiation with wavelengths in the range of about 2.7 to about 5.92 micrometers as target foods absorb radiation at these wavelengths. In some embodiments, infrared emitter 201 is an iron-chrome-aluminum heating element wrapped in ceramic fiber insulation. In some embodiments, infrared emitter 201 is composed of an open ceramic insulator supporting a nichrome coil. In some embodiments, infrared emitter 201 may be a quartz tube. In still other embodiments, infrared emitter 201 may be an infrared light bulb. Infrared emitter 201 may be round, square, rectangular, cylindrical, or any other shape. Infrared emitter 201 may be replaceable or permanently installed into lamp 110. Infrared emitter 201 provides a means for generating infrared radiation that can be used to heat an intended target, e.g., prepared food.
In some embodiments, infrared emitter 201 features a ceramic heating element that generates infrared (electromagnetic radiant infrared energy) to transfer heat energy via invisible electromagnetic energy waves. Using the ceramic heating element to provide the heat may be advantageous because it delivers an even, gentle heat and zone control (i.e., the ceramic element generates infrared energy that is absorbed solely at the area it is directed). Furthermore, electric infrared may produce virtually instant heat, without the need to wait for heat buildup. Infrared heating, is not generally dependent upon air movement like convection heat. Additionally, the ceramic heating element that provides electric infrared heat may be one of the cleanest methods of heating. There are no by-products of combustion and the heating element adds nothing to nor takes anything from the air. In this way, a ceramic heating element helps maintain the flavors of the foods the heat lamp is warming. The infrared emitter may be a custom-built part or a light bulb. The custom part may be a coil of resistance wire (such as is commonly used in a toaster or a space heater) that glows red when energized. The resistance wire may emit electromagnetic energy across a broad spectrum with the predominant energy being infrared.
In some embodiments, some infrared radiation from infrared emitter 201 is directed generally upward or sideways toward outer shade 112 rather than generally downward toward the food. This misdirected energy would be wasted if allowed to continue in that direction and could contribute to a dangerous heating of outer shade 112 and handle 111. First reflector 202 reflects at least some of this misdirected infrared radiation generally downward toward the food to be heated. In some embodiments, outer air gap 204 exists between outer shade 112 and first reflector 202 to allow convective air flow out vents 205, which cools outer shade 112 and first reflector 202 and prevents conductive heating of outer shade 112 via hot stagnant air trapped between outer shade 112 and first reflector 202. In some embodiments, outer air gap 204 is filled, at least in part, with an insulating material. In some embodiments, outer shade 112 and first reflector 202 are connected in an airtight manner (thus forming a double-walled chamber) with a substantial amount of the air in air gap 204 evacuated to form a vacuum insulator.
In some embodiments, first reflector 202 is a generally reflective, generally continuous, metal shield (e.g., thin rolled steel or aluminum) wrapped around the sides and much of the top of infrared emitter 201 leaving air gap 206 between first reflector 202 and infrared emitter 201. In some embodiments, first reflector 202 may include a series of louvers at or near the top of first reflector 202. The louvers may reflect infrared radiation downward at an angle. The louvers may allow convective air flow to pass through. In some embodiments, the louvers are arranged radially. In some embodiments, first reflector 202 may be formed from a heat-safe material (e.g., an engineering plastic) coated with a reflective foil or paint. Air gap 206 allows convective air flow around infrared emitter and out chimney 113 to prevent conductive heating of first reflector 202 via hot stagnant air trapped between first reflector 202 and infrared emitter 201.
In some embodiments, second reflector 203 is provided to prevent leakage of infrared radiation through inner air gap 206 and out chimney 113. Second reflector 203 may be positioned to reflect radiant energy downward while still maintaining inner air gap 206 and allowing, convective air flow through inner air gap 206 and out chimney 113. For example, infrared radiation may follow path 214 upward from infrared emitter 201 before being reflected by second reflector 203 and then first reflector 202. In some embodiments, second reflector 203 is a generally reflective, generally continuous, metal shield (e.g., thin rolled steel or aluminum) wrapped around the top of infrared emitter 201. In some embodiments, second reflector 203 may be formed from a heat-safe material (e.g., an engineering plastic) coated with a reflective foil or paint. In some embodiments, second reflector 203 is formed from a series of louvers. The louvers may reflect infrared radiation downward at an angle. The louvers may allow convective air flow to pass through. In some embodiments, the louvers are arranged radially. The combination of one or more reflectors provides a means for reflecting infrared radiation toward an intended target that increases the efficiency of the heat lamp and reduces heating of the outer shade and handle. In certain embodiments, second reflector 203 may rotate to aid in ventilation of the high temperature components.
In some embodiments, the only mechanical coupling between outer shade 112 and the high temperature components (e.g., infrared emitter 201 and reflective shades 202 and 203) is chimney 113. As illustrated in
Vents 205 allow heated air to escape out the top of lamp 110. In some embodiments, a single vent 205 may accommodate chimney 113 to allow heated air to escape only through chimney 113, as shown in
Thermal-cutoff 213 causes an automatic disconnect of power to infrared emitter 201 in the event of an over-temperature condition. Thermal-cutoff 213 may protect internal components from dangerous temperatures in order to prevent or diffuse a fire hazard. Under normal operating conditions, convective airflow passes through air gaps 204 and/or 206, cooling the internal components and maintaining safe operating conditions. In one abnormal circumstance, where vents 205 and chimney 113 become blocked, operation of infrared emitter 201 may cause dangerous temperatures to form within lamp 110 as no convective airflow would be possible. In another abnormal circumstance, if the open end of lamp 110 (i.e., the end with grille 114) were to come in contact with a surface, especially a soft surface, that contact could restrict or block convective airflow. A significant restriction or blockage of airflow through air gaps 204 and/or 206 could result in a dangerously high internal temperature, possibly causing fire, structural damage, and/or breakdown of electrical insulators. Because of the arrangement of air gaps 204 and 206, heat lamp 100 can indirectly “sense” the airflow restriction and shut down the infrared emitter before a dangerous condition occurs. In some embodiments, thermal cutoff 213 may be thermally insulated from outer shade 213 to react to the air temperature in air gap 204. In some embodiments, thermal-cutoff 213 may be thermally connected to outer shade 213 to react to the shade temperature.
Thermal-cutoff 213 may be a single use or resettable thermal-cutoff device. In some embodiments, thermal-cutoff 213 utilizes a thermal pellet, e.g., made of wax, that normally compresses a spring, holding an electrical switch closed. Once the temperature exceeds a predetermined threshold temperature, the wax melts, thereby releasing the spring and opening the switch. In some embodiments, thermal-cutoff 213 utilizes a bimetal thermal protector, which may allow for automatic self-reset once the temperature has decreased. In some embodiments, thermal-cutoff 213 may be implemented using a temperature sensor (e.g., a thermocouple) combined with a controller and a controllable switch. In certain embodiments, multiple thermal-cutoff devices may be utilized. In some embodiments, a mechanically operated thermal-cutoff to provide a high threshold fail-safe may be combined with a lower threshold control circuit. In some embodiments, two mechanically operated thermal-cutoff devices may be wired in series, one being automatically resettable with a lower threshold and one being a single-shot device with a higher threshold. Thermal cut-off 213 provides a means for preventing or interrupting a thermal overload condition. In some embodiments, the threshold temperature for thermal cut-off 213 may be set to a temperature at which a user may be burned by escaping gases or by brief contact with the outer shade. In some embodiments, the threshold temperature for thermal cut-off 213 may be set to a fraction of the melting or plastic point of chimney 113 to prevent melting or deformation of the same, even if the remaining heat energy continues to heat chimney 113 after emitter 201 has been turned off.
a and 3b provide two views of the support arm knuckle assembly from a head-on angle and a side view angle, according to certain embodiments of the present invention.
Outer housing 301 may be constructed in two interconnecting pieces, one connecting to upper arm member 124 and the other connecting to lower arm member. Joining those two pieces is barrel nut 302 and screw 304, together providing compressive force on the two interconnecting pieces. Barrel nut 302 includes tabs 303 that fit into housing key slots 305 to allow a limited range of motion of knuckle assembly 300. Friction washers 306 prevent unintended movement of knuckle 300 by countering the gravitational force generated by lamp 110. Instead of friction washers 306, additional tabs and slots may be provided in barrel nut 302 and outer housing 301 to allow for discrete extension positions. In some embodiments, the user would loosen screw 304 to adjust knuckle assembly 300. In other embodiments, a spring may be provided to allow the additional tabs to move to the next slot by compressing the spring. In other embodiments of the invention, stops may be mounted in the knuckle housing to prevent the knuckle assembly 300 from rotating past 180 degrees.
b illustrates a cut-away side view of knuckle assembly 300 illustrating cable pathway 310. Cable pathway 310 may be completely or partially enclosed and may wrap around barrel nut 302. Because barrel nut 302 may be keyed into outer housing 301 (as described above), wires in cable pathway 310 are protected from shearing or crimping forces that would otherwise be applied if knuckle assembly 300 were extended past about 180°.
In some embodiments, the features of knuckle assembly 300 are incorporated into upper lamp pivot 121 (and lower lamp pivot 123). In these embodiments, the range of extension of upper lamp pivot 121 may be limited to always maintain a slight cant to lamp 110, even when stowed. In this way, airflow is never completely restricted through lamp 110, allowing efficient cooling even after the lamp is turned off and stowed. In some embodiments, a fan is incorporated into base 130 forcing air through a channel in support arm 120 and into lamp 110 to assist in cooling lamp 110. In alternative embodiments, the convective flow is reversed and a fan is located in the lamp 100 to direct air downward toward the target. Placement of the fan in the base may allow for a larger, more powerful fan and it would not be as likely to overheat because it would not be proximate the infrared emitter. A fan in the base may either push or pull the air through the armature.
Base 601 houses certain components of heat lamp 600 and provides a structural connection to foundation 610. Base 601 provides a channel for receiving arm member 602 and connects to foundation 610 to provide indirect lateral support for lamp 110. Base 601 includes a channel for receiving power cord 604, convenience outlet 605, circuit breaker 606, and tip-over switch 607. Convenience outlet 605 allows a user to connect a second heat lamp 600 to form a series of daisy-chained lamps, e.g., in a buffet line. In some embodiments, circuit breaker 606 provides over-current protection for heat lamp 600 by disconnecting lamp 110 in the event that current through the wires to lamp 110 exceeds a predetermined level. In some embodiments, circuit breaker 606 disconnects power to lamp 110 and convenience outlet 605 in the event that current received through power cord 604 exceeds a predetermined level.
Foundation 610 provides a stable platform for heat lamp 600 and a convenient interface for user interaction and control. In some embodiments, foundation 610 may be a thin base generally as large as the infrared output pattern produced by lamp 110. In some embodiments, foundation 610 may be larger than the infrared output pattern to protect the surface below lamp 110. In certain embodiments, foundation 610 may be thermally insulated and/or opaque to protect an underlying countertop or furniture surface from the high food temperature and/or infrared radiation. Silicone pads may also be used on the bottom of the foundation to protect a countertop. In certain embodiments, foundation 610 may be reflective to protect the countertop or furniture surface without absorbing heat, which would increase the temperature of foundation 610. To protect the countertop or furniture surface, foundation 610 may need to be as broad as the primary heating area under lamp 110, for example at least 16 inches in each horizontal dimension if a circular infrared emitter is 15 inches above foundation 610. In some embodiments, foundation 610 is large enough to accommodate a standard 9″ by 13″ casserole dish.
The foundation 610 may also comprise a storage compartment for a variety of accessories including, for example, spare or replacement infrared radiation bulbs, serving utensils, etc. One aspect of the invention comprises serving utensils that remain cool to the touch in the presence of infrared energy. Serving utensils may be made of silicone or any material that that does not absorb infrared energy or that does not become hot in the presence of infrared energy.
According to alternative embodiments of the invention, the foundation 610 comprises a hot plate so as to heat the target both from the infrared radiation above and the hot plate below. Any hot plate structures known in the art may be incorporated and used in the foundation. In one embodiment, the foundation 610 may comprise a heater element that may be an etched foil design element comprising circuitry for a Kapton™/Polyimide heater. The heater element may be constructed of a material that is a polyimide polymer, for example, a Kapton™ material. Note that Kapton™ is a trademark of the DuPont™ Corporation. A Kapton™ material, in film form, can provide enhanced dielectric strength in very thin cross sections and very good bonding and heat transfer capabilities. Use may be made of a Kapton™ film having a thermal conductivity below 0.5 W/mK and a dielectric strength exceeding 1250 V, which can be achieved with a thickness between 0 and 100 μm. The heater can therefore be implemented as a Kapton™ type heater. Note that resistive heater element may be implemented as a Kapton™ type heater or a heater formed of a polyimide polymer, depending upon design considerations.
Kapton™/Polyimide heaters made with this DuPont™ thin film may be transparent, lightweight, flexible and are electrically strong. Kapton™/Polyimide may be compatible with foil element alloys such as inconel, nickel, copper, and stainless steel. They may have low outgassing properties, may be resistant to solvents. They may work well with adhesive systems that permit higher operating temperatures. Thermal control and sensing devices may be incorporated into the hotplate.
The hotplate may comprise a thin outer layer of Kapton™ (first insulating film) and a thicker layer of Kapton™ (second insulating film) between which two layers there is a layer of electrically conductive material (heater element). The layer of electrically conductive material could be formed by vacuum depositing a layer of conductive material onto the second insulating layer and then bonding the first insulating film to the layer by way of layers of adhesive material. Adhesive layers may be painted onto the insulating film layers.
Heater element may be a deposited ink on a dielectric that is bonded to a metal substrate. Once energized, the conductive inks may provide the heat source to elevate the soleplate temperature. The ink pattern may be two side-by-side undulating ink deposit strands similar to the strands. The ink strands may connect to form one continuous electrically resistant heat generating ink coil that is bonded to a metal substrate.
Foundation 610 may include control panel 611 (illustrated in
Set point indicator 613 indicates the desired output or target temperature for lamp 110. In some embodiments, set point indicator 613 provides a display of a temperature value. In some embodiments, set point indicator provides a discrete output level indicator (e.g., high/low or a range of multiple discrete output levels).
Current temperature indicator 614 indicates the current temperature as measured by temperature sensor 612. In some embodiments, current temperature indicator 614 displays the current temperature as a numeric value. In some embodiments, current temperature indicator 614 displays the current temperature as a value on a range, e.g., a bar graph indicator. In some embodiments a color scheme may indicate a danger zone temperature as a red background or with a red light.
Set point adjustment interface 615 allows a user to adjust the set point. In some embodiments, set point adjustment interface 615 is a switch or knob. In some embodiments, set point adjustment interface 615 is a pair of buttons or touch sensors, one for increasing the set point and one for decreasing the set point.
Error indicator 616 provides a display of recognized error conditions. In some embodiments, error indicator 616 warns a user of a high temperature condition in lamp 110, which has required or may soon require an automatic shutoff of lamp 110. In some embodiments, error indicator 616 warns a user of an unsafe food temperature condition, e.g., one signaled by a low reading at temperature sensor 612.
Fan 620 provides active airflow adjustment. In some embodiments, fan 620 provides an active assist to the natural convective airflow by drawing additional cool air through lamp 110 and out the vents and/or chimney at the top of lamp 110. In some embodiments, fan 620 may blow air downward to overpower the natural convective airflow and force the heated air downward toward the food item. Fan 620 may be manually controlled or automatically controlled. Fan 620 may have multiple speeds to adjust for varied ambient temperature conditions or internal conditions. Fan 620 may be triggered by an over-temperature condition within lamp 110. The fan 620 may operate in any of three modes. First, the fan 620 may pull air past the heating element in the same direction as convention. Second, the fan 620 may push air down past the heating element in a direction opposite the direction of convection. Third, the fan 620 may direct air flow in a cross-wise direction relative to the direction of convection. For any of the modes of operation, the fan 620 may be located either upstream or down stream relative to the heating element and the direction of convection. Alternatively, the fan 620 may be positioned on the side of the outer shade so as to pressurize an enclosed space such that the outlet of that pressurization directs air either up (to reinforce convection) or down to improve heat delivered to the target.
a and 7b illustrate two slightly different views of chimney 113, according to certain embodiments of the present invention. Chimney 113 includes chimney grille 701, high-temperature mount points 702, outer shade interface 703, and side air port 704. In some embodiments, chimney 113 may be a one-piece, molded part made from an engineered plastic or other suitable material. In some embodiments, chimney 113 may be an assembly of multiple parts and materials with different thermal and structural characteristics.
Chimney grille 701 provides an external exhaust port for convective air flow while preventing insertion of foreign objects or other direct contact between internal, high-temperature components and people, pets, or things. High-temperature mount points 702 provide a direct interface between high-temperature elements (e.g., one or more of first heat shield 202, second heat shield 203, and infrared emitter 201). This direct interface allows chimney 113 to physically support and stabilize the high-temperature elements. Outer shade interface 703 provides a direct interface between chimney 113 and outer shade 112. Outer shade interface 703 allows outer shade 112 (and indirectly support arm 120) to support chimney 113 and, indirectly, the high-temperature components. In some embodiments, outer shade interface 703 extends from chimney 113 to maintain air gap 204.
Side air port 704 may allow air flow through air gap 204 into chimney 113 (see
In certain embodiments, thermal-cutoff 213 may be mounted in thermal contact with outer shade 112 and configured with an appropriate threshold to maintain a safe temperature for that exposed surface. For example, a threshold may be set well below a temperature that might cause a contact burn in that outer shade 112 may continue to get hotter even after power is disconnected from infrared emitter 201. In some embodiments, thermal-cutoff 713 is mounted within chimney 113 in order to react to restricted or inadequate convective air flow through chimney 113.
The heater element may be an infrared source of the type that is energized very quickly. The heater element may comprise infrared quartz tubes. Any number of tubes may be positioned in any pattern. Further, the tubes may take any shape, for example, linear, arcuate, angled, figure C, figure S, square, circular, etc. Quartz tubes have electrical leads for electrically communicating with temperature control knob and electric cord. Tube clips may be mounted to the first heat shield for engagement with quartz tubes. Tube clips may suspend quartz tubes over a reflective material so as to disperse energy more evenly. The interior surfaces of the first heat shield may be coated with an infrared reflective coating to reflect energy emitted by quartz tubes toward the target. Examples of reflective coatings or materials include: gold, anodized aluminum or any other high temperature, low emissivity material. Other components may be coated with an infrared absorptive coating. Examples of absorptive coatings or materials include: ceramic, porcelain or any other high emissivity material.
The infrared source may be a tungsten type lamp. The infrared source may be used to quickly heat up the target. Quartz lamps may also be used. Quartz tubes may have a Watt density between about 65-120 Watts/linear inch. Quartz tubes may also have an internal gold reflector. Quartz tubes and quartz lamps may have the ability to reach maximum temperature very quickly, if not instantly. Further, quartz tubes and quartz lamps may reach maximum operating temperatures of 870° C. to 1370° C.
In some embodiments, head assembly 110 includes fan 620 for providing powered air flow through chimney 113. Fan 620 may pull heated air through chimney 113 or may push ambient air through chimney 113 towards emitter 201. In some embodiments, fan 620 may be mounted to outer shade 112, and outside of the flow of heated air.
a and 9b provide two views of a heat lamp, according to certain embodiments of the present invention. Heat lamp 100 includes lamp 110 may be connected in a fixed relationship with support arm 120, which may be connected in a fixed relationship with base 130. Support arm 120 may include a pivot and a counterbalance. Heat lamp 100 is illustrated in an operating (or open) position and a storage (or closed) position as well as in a transition between the two positions.
While embodiments of this disclosure have been depicted, described, and are defined by reference to example embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and are not exhaustive of the scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 61/364,243 filed Jul. 14, 2010, entitled “Heat Lamp,” which is incorporated herein in its entirety.
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| 20120145699 A1 | Jun 2012 | US |
| Number | Date | Country | |
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