Warming oven

A warming oven includes a housing that forms a chamber and has a heat insulating material. A support member positioned within the chamber has a support surface. Heating elements are arranged within the chamber in an opposing relationship to the support member. The heating elements generate radiant heat towards the support member and have passages to heat an air flow through these passages and across the heating elements. An air circulator communicates with the chamber and includes a fan to generate the air flow, an exhaust to direct the air flow, and an intake to receive the returning air flow. A temperature sensor senses a temperature of the air flow. A controller communicates with the temperature sensor and selectively controls the air circulator and/or the heating elements to adjust the generated air flow or the heat output for temperature regulation. This temperature regulation can provide for an operating temperature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to warming devices, and in particular, to a warming oven for thermoplastic materials.

2. Description of Related Art

Various medical procedures are performed when a patient is immobilized. For example, certain radiation treatments implement a thermoplastic immobilization mask to prevent movement of the patient's head during radiation therapy. These thermoplastic masks can be warmed so that the thermoplastic material can be altered and adjusted. As an example, the mask is warmed so that it can be contoured in relation to the patient's head to provide a relatively precise fit.

Presently there are various warming devices on the market that can warm these masks. One example of a warming device is a warm water bath. When using the warm water bath, the mask is deposited within the warm water of the bath and is heated by the heat from the warm water. A possible drawback with the warm water bath is that it can be relatively messy and cumbersome when removing the thermoplastic mask from the warm water. Further, by having the thermoplastic mask warmed by the warm water, the mask can retain and exude a relatively harmful humidity level to sensitive equipment. As an example, sensitive equipment such as a Computed Tomography (CT) imaging machine can be harmed by this humidity level.

Another existing device for warming thermoplastic masks is a plate and cup warming device. Similar to the warm water bath, the plate and cup warming device also has certain drawbacks. For example, the plate and cup warming device is generally configured for installation into a kitchen cabinet. This configuration can limit the area and manner in which this device can be implemented. Further, the interior dimensions of the drawer of the plate and cup warming device may not be adequate in accommodating the relatively larger thermoplastic masks. For example, thermoplastic masks that have a size of 24 inches (in)×18 in (60.96 centimeters (cm)×45.72 cm) may not be accommodated by the drawer of the plate and cup warming device. Additionally, the plate and cup warming device is not traditionally considered for heating thermoplastic masks. Therefore it may not be feasible to warm a mask with the plate and cup warming device since the device is not configured for that operation.

Another warming device out on the market incorporates a silicone beating pad having a 1300 watts capacity, combined together with four relatively small computer fans for air circulation. The drawbacks for this device include the small heat capacity that is generated, which can cause this device to take a relatively extended time in reaching an appropriate operating temperature. Another drawback is that the unregulated flow from the computer fans can create uneven heating. Additionally, the lack of substantial insulation can cause the external surfaces of this warming device to get relatively hot. This can result in surfaces that are hot to the touch and heat losses that may extend process times.

Also for consideration is simply re-purposing an existing “convection oven” used in food preparation to process the thermoplastic masks. Similar to the previously mentioned devices, there are drawbacks with this approach as well. For example, standard convection ovens are typically not suitable due to the relatively low temperature generally required to process the thermoplastic mask. Further, uneven air temperatures are typically present in convection ovens throughout the interior of the oven. Generally speaking, a convection oven is often intended to operate at relatively higher temperatures and for a relatively longer process time than is acceptable for thermoplastic mask processing and preparation.

Therefore, it is desirable for a device that has an adequate process drawer size so as to accommodate the relatively larger thermoplastic masks, such as those masks that are about 24 in×18 in (60.96 cm×45.72 cm) plus clearance in size. Further, it is also desirable for a warming device that can process select support cushions which may have been pre-formed and may have a thickness of up to about four inches (10.16 cm). In addition, it is desirable for a device that can be brought to an appropriate operating temperature so as to provide for a relatively shorter time period to ready for use.

Additionally, it is desirable for a warming device that is capable of reducing the processing time of the thermoplastic mask. Further, it is desirable for a warming device that has a heating capacity that can be maximized when using a standard 15 amp (A) household current at 120 volts alternating current (VAC) or at 8 A European Union (EU) current at 220 VAC. Furthermore, it is desirable for a device to have a temperature controller to provide for precise temperature control.

Thus, a warming oven for addressing the aforementioned problems is desired.

SUMMARY OF THE INVENTION

A warming oven includes a housing that forms a chamber to receive an object to be heated. The housing is associated with a heat insulating material that is adapted to reduce heat transfer from the chamber. Additionally, the warming oven includes a support member which can be positioned within the chamber. The support member has a support surface adapted to receive and support the object that is to be heated. Further, a plurality of heating elements are arranged, such as in a spaced relation, within the chamber and in an opposing relationship to the support member. The plurality of heating elements are adapted to generate a radiant heat in a direction towards the support member. Further, the heating elements have passages to heat an air flow directed through these passages and across the corresponding heating elements.

The warming oven also includes an air circulator in communication with the chamber. The air circulator includes a fan with an accompanying fan housing to generate the air flow in the chamber, an exhaust to direct the air flow from the air circulator into the chamber, and an intake to receive the air flow returning to the air circulator from the chamber. This air circulator creates a flow path for the generated air flow through the chamber from the exhaust to the intake. The exhaust directs the generated air flow along the flow path in a first direction across the heating elements through the passages of the heating elements to heat the air flow. The heated air flow then circulates along the flow path in a second direction toward the air circulator to mix the heated air flow with the radiant heat generated by the heating elements. This mixing of the heated air flow with the radiant heat can provide a substantially uniform operating temperature in the chamber to heat the object.

The warming oven further includes a temperature sensor for sensing a temperature of the air flow in the chamber. Additionally, a controller communicates with the temperature sensor to receive the sensed temperature of the air flow. Based on the received sensed temperature, the controller selectively controls at least one of the air circulator and the heating elements to adjust at least one of the generated air flow or the heat output of the heating elements for temperature regulation within the chamber. This temperature regulation provides for a selected substantially uniform operating temperature so that the object can be warmed appropriately.

DETAILED DESCRIPTION OF THE INVENTION

The warming oven allows for an object, such as a thermoplastic mask used in patient immobilization, to be warmed. The warming oven accomplishes this warming through an arrangement in which a plurality of heating elements are arranged together in an opposing relationship to a support member that supports the thermoplastic mask. An air circulator generates an air flow implemented by a fan with an accompanying fan housing. This generated air flow is carried across the plurality of heating elements and throughout the chamber. A temperature sensor within the chamber senses the temperature of the air flow in the chamber. Based on this sensed temperature, a controller selectively controls at least one of the air circulator and the heating elements to adjust at least one of the generated air flow or a heat output of the heating elements for temperature regulation within the chamber to provide for a selected substantially uniform operating temperature.

Referring toFIGS. 1-10, a warming oven100is disclosed. The warming oven100includes a housing102which acts an enclosure that forms a chamber104. This housing can be of any suitable arrangement or materials, depending on the user's needs. For example, the housing102can be an exposed frame of an extruded shaped aluminum material with removable panels. Another possibility is that the housing102is a double clam shell base/cover assembly. The housing102can be used or provided with either choice of enclosure, for example. Points of consideration are that the exposed frame enclosure can be relatively costly to manufacture. On the other hand, the clam shell enclosure can be both relatively cost effective and relatively easier to assemble. Further, the housing102can come in multiple pieces, or have a smooth surface, or include a stainless steel material, or it can be a painted enclosure.

The chamber104that is formed by the housing102is adapted to receive an object106that is to be heated. The object106can be any object that can be warmed and fits the user's needs. For example, the object106can be a thermoplastic material, such as a thermoplastic mask used for patient immobilization in certain radiation treatment therapies. The thermoplastic mask can be warmed while within the chamber104so that it can become malleable. Once removed from the chamber104, the thermoplastic mask can be contoured to fit a portion of a patient's body. For example, the thermoplastic mask can be contoured to fit onto a patient's face so that the patient's head is immobilized during a radiation therapy treatment. The thermoplastic mask that can be heated by the warming oven100can be various shapes and sized. For example, the thermoplastic mask can be up to about 24 in×18 in (60.96 cm×45.72 cm) plus clearance in size. Additionally, the object106can be other medical materials or devices, simply depending on the user's needs. For example, the object106can be a support cushion having a thickness of up to about four inches. Also, embodiments of the warming oven100can have other suitable applications for warming objects in other medical or non-medical applications, for example, and should not be construed in a limiting sense.

Continuing with the housing102, a heat insulating material108is associated with the housing102. The heat insulating material108can be a number of various materials that allow for heat insulation during a warming process. For example, the heat insulating material108can be about a one inch (2.54 cm) thick fiberglass insulation material, as can be combined together with a reflective foil backing, applied on all sides, top and bottom of the chamber104. By placing the heat insulating material108on all sides, top and bottom of the chamber104, it can allow the chamber104to be relatively fully insulated. Further, it can allow for the warming oven100to limit waste heat. As an example for this, the heat insulating material108can allow the housing102to remain cool to the touch, which indicates that heat transfer from the chamber104is reduced. Other materials can be suitable for selection of the heat insulating material108, depending on the user's needs.

As shown inFIGS. 2, and 6-7, the object106can be positioned within the chamber104by being supported by a support member110. The support member110is adapted to be positioned within the chamber104, as specifically illustrated inFIG. 6. The support member110includes a support surface112, which is adapted to receive and support the object106that is to be heated. The support member110and the accompanying support surface112can come in a grid configuration or another other suitable arrangement that allows for the object106to be supported. If a thermoplastic mask is selected as the object106, the support member110and the accompanying support surface112can be of a size that accommodates the relatively larger sized thermoplastic masks. As an example the support member110can accommodate masks about 24 in×18 in (60.96 cm×45.72 cm) plus clearance in size or even support cushions having a thickness of up to about four inches. Additionally, the support surface112of the support member110can be made of or coated with a polytetrafluoroethylene (PTFE) material to allow for relatively easier removal of the object106from the support surface112.

As illustrated inFIGS. 2 and 5-7, the support member110can be selectively moved in relation to and within the chamber104. The selective movement of the support member110can be accomplished by the support member110being in connection with a movable member114. The movable member114can be placed into an open position, as illustrated inFIGS. 2 and 7. In the open position, the object106can be positioned outside the chamber104. Further, in this open position, the object106can be removed from the warming oven100.

As illustrated inFIGS. 5 and 6, the movable member114can also be placed into a closed position. In the closed position, the object106is positioned within the chamber104. The closed position is the suitable position during operation of warming oven100. Therefore, the movable member114drives the selective movement of the support member110in and out of the chamber104, which allows for the support member110to be positioned in and out of the housing102so that the object106can be heated in the chamber104.

The movable member114can be any suitable member, such as a process drawer113, such as can have a handle115, among other examples. If the process drawer113is selected as the movable member114, than the movable member114can include an arrangement with a front flange116at a front end117of the process drawer113as can provide a front member of the process drawer113. Further, the arrangement can also include the movable member114having a rear flange118positioned near an opposite end119of the process drawer113that is adapted to restrict access to an interior of the chamber104. The front flange116is illustrated inFIGS. 1, 2, 5, and 7. The rear flange118is illustrated inFIG. 2. The rear flange118can prevent contact of the heating elements122or a fan132by the user. Further, a guard123is installed just beneath the plurality of heating elements122to additionally prevent contact by the user.

In addition to the front flange116and the rear flange118, the movable member114can further include downturned flanges120at a left edge and a right edge of the process drawer113. These downturned flanges120allow facilitation of air flow across the chamber104. The downturned flanges120are illustrated inFIG. 3. Therefore, if the movable member114is the process drawer113, the process drawer113is arranged to facilitate a substantially full right to left cross flow of the recirculated air across the chamber104that is relatively low to a drawer base surface of the process drawer113, for example. This air flow can be facilitated by incorporating the front flange116and the rear flange118at nearly a chamber height of the chamber104and with the downturned flanges120at the left and right edges of the drawer, for example.

The movable member114can include a movement member that allows for the movement of the movable member114to allow for the selective movement of the support member110, such as the movable member sliding in and out of the chamber104. The movement member can be any suitable member that allows for movement, such as a rack and pinion arrangement, or wheels, among other examples. The movement member can be positioned on a bottom surface of the movable member114to allow not only for movement but to also provide support for the movable member114while in the open position and in the closed position. Further, the movement member is such that it can enhance the longevity of the movable member114. The movement member can also be a segmented arrangement with segmented slides laid flat with a main slide segment fastened to a base of the housing102and another segment attached to an underneath of the movable member114.

The warming oven100further includes a plurality of heating elements122, as illustrated inFIGS. 3-8. The heating elements122can be arranged in a spaced relation within the chamber104. Further, the heating elements122are also in an opposing relationship to the support member110. Each heating element122out of the plurality of heating elements122can be an electric resistance finned strip heater having finned strips124to generate heat, such as a radiant heat128. The heating elements122are un-shrouded, except for the guard123, shown as a protective grate inFIGS. 5-7. The un-shrouded placement of the heating elements122can provide the radiant heat128to relatively accelerate the heating of the chamber104and can facilitate air flow within the chamber104and adjacent to a surface of the object106.

Additionally, the heating elements122can be positioned on a reflective ceiling121of the chamber104, such as can include a reflective foil. In this arrangement the plurality of heating elements122are adapted to generate the radiant heat128in a direction toward the support member110, as illustrated inFIG. 3. Therefore, the heating elements122can be positioned between the reflective ceiling121and the guard123. The heating elements122can be alternately placed below the support member110so as to provide a resultant increase in height of the warming oven100. In such an instance the movable member114would be an open flow-through design to permit passage of a heated air. Additionally, a fan air path would also be reversed to flow from the bottom up through the chamber104.

As shown inFIGS. 3-6, an air circulator130is in communication with the chamber104. The air circulator130includes a fan132with an accompanying fan housing134to generate an air flow138in the chamber104. The fan housing includes an exhaust136and an intake146. The fan132with accompanying fan housing134can be any suitable commercially available fan and fan housing combination, such as an extra wide squirrel cage fan. If the extra wide squirrel cage fan is selected, a wide even flow of air can be generated by the inherent design of this fan type. For example, the fan132and accompanying fan housing134can be a 12 in (30.48 cm) wide squirrel cage.

As illustrated inFIG. 3, the exhaust136directs the generated air flow138from the air circulator130into the chamber104. The finned strips124of each heating element122, such as the adjacent ones of the finned strips124, can form a corresponding passage126(FIG. 8) to allow the generated air flow138to flow from one heating element122to an adjacent heating element122. Further, as the generated air flow138flows through the passages126, the generated air flow138is heated as it passes through the corresponding passages126, with this heated air flow142circulating along a flow path143, as shown inFIGS. 3 and 8. Thus, the passages125between the finned strips124allow for the generated air flow138to be heated when the air flow138is directed through the passages126and across the corresponding heating elements122. In summary, the fan132and accompanying fan housing134can be used to draw a warmed air or a pre-warmed air through a calibrated orifice, such as the intake146, and then to expel this warmed air or pre-warmed air out through the exhaust136as the generated air flow138across the finned strips124of the heating elements122.

As shown inFIG. 3, the exhaust136directs the generated air flow138along the flow path143in a first direction145across the heating elements122through the passages126of the heating elements122to heat the generated air flow138. Further, the heated air flow142circulates along the flow path143in a second direction147toward the air circulator130to mix the heated air flow142with the radiant heat128generated by the heating elements122. In addition to this, the plurality of heating elements122can divert a portion of the generated air flow138from the flow path in a direction141towards the support member110by the finned strips124of the heating elements122. This diversion of the generated air flow138is illustrated inFIG. 3. Diverting the generated air flow138can create turbulence in the generated air flow138in a direction toward the support member110. This turbulence in the generated air flow138is represented as a turbulent air flow140inFIG. 3.

The turbulent air flow140can further provide homogenization of e heated air flow142within the chamber104during a mixing of the heated air flow142with the radiant heat128. This mixing of the heated air flow142with the radiant heat128can provide for a substantially uniform operating temperature in the chamber104to heat the object106. In the case of a thermoplastic mask being the object106, the uniform operating temperature can be about 165 degrees Fahrenheit (° F.) (73.89 degrees Centigrade (° C.)). The turbulent air flow140can assist in achieving this selected substantially uniform operating temperature of about 165° F. (73.89° C.) within the chamber104. It is also desirable, in addition to the selected substantially uniform operating temperature of about 165° F. (73.89° C.), that the warming oven takes a time period of about 15 minutes to warm up from “cold” to operating temperature, referred to as a heat up time, to achieve this substantially uniform operating temperature of about 165° F. (73.89° C.) within the chamber104. If a thermoplastic mask is the object106, the thermoplastic mask can be processed in as little as about 10 minutes, for example.

As stated previously, the exhaust136of the fan housing134directs the generated air flow138from the air circulator130into the chamber104. The reverse flow of the heated air142back across the chamber104eventually flows into the intake146of the fan housing134. Thus, the air circulator130allows for the flow path143to be created that allows the generated air flow138to flow through the chamber104from the exhaust136to the intake146. In summary, the air within the chamber104flows through the chamber104and then reverses flow to flow back across the chamber104so that a substantially thorough homogenization of the heated air142can occur so that all corner areas of the chamber104are maintained at the same or substantially the same temperature.

It should be noted that any number of heating elements122can be implemented with the warming oven100, depending on the user's needs. Further, each heating element122can have a differing or same capacity value as another heating element122. For example, if three heating elements122are implemented, one heating element122can have a capacity of 725 watts (W), while the other remaining two heating elements122can have a capacity of 500 W each, as can depend on the use or application.

It is desirable that the higher capacity heating element122, for example the heating element122that has a capacity of 725 W, is placed closest to the air circulator130, and specifically closest to the fan132. Thus, lower capacity heating elements122, such as heating elements122having 500 W capacities, would be relatively farther away from the air circulator130compared to a 725 W capacity heating element122. To summarize, in a desirable arrangement of the heating elements122in the chamber104, at least one of the heating elements122has a higher capacity for heat output than at least one other of the plurality of heating elements122so as to provide a higher heat output than at least one other of the plurality of heating elements to adjust for heat loss in the generated air flow138along the flow path143.

The warming oven100further includes a temperature sensor148to sense a temperature of the air flow in the chamber104, such as the heated air flow142. As illustrated inFIGS. 4 and 7, the temperature sensor148can be positioned within the chamber104in an opposing relationship to the air circulator130, desirably at an opposite end of the chamber104from the air circulator130. Additionally, the temperature sensor148can be positioned in a horizontal orientation. Further, the temperature sensor148can be any suitable temperature sensor, for example, a thermocouple. Regarding the thermocouple, a relatively long and/or thin thermocouple can be used for sensing air temperature as opposed to a relatively shorter, fatter sensor that is intended to be submersed in water, for example.

The warming oven100also includes an exemplary controller150, as illustrated inFIG. 9. The controller150is in communication with the temperature sensor148to receive the sensed temperature of the air flow. Based on this received sensed temperature from the temperature sensor148, the controller150selectively controls at least one of the air circulator130and the heating elements122to adjust at least one of the generated air flow138or the heat output of the heating elements122for temperature regulation within the chamber104. This temperature regulation within the chamber104can provide the selected substantially uniform operating temperature, which as mentioned above, is about 165° F. (73.89° C.) for when a thermoplastic mask is selected as the object106. The temperature sensor148provides a closed loop operation with the controller150to maintain the temperature inside the chamber104to a relatively precise degree. The controller150and its accompanying components can be located within an electrical cavity149within the housing102, as shown inFIG. 7. This electrical cavity149can be below the air circulator130, or any other suitable location.

The controller150can include a proportional-integral-derivative (PID) controller, such as can include an Athena® Series 16C Temperature/Process Controller, for example, in communication with the plurality of heating elements122, such as through a solid state relay (SSR), for example. The controller can be a control system with a self-contained analog controller and no SSR. Regardless of which type of controller150is selected, the same or other suitable temperature sensor148can be used. Another controller configuration can include a countdown to off timer to automatically turn off the plurality of heating elements122of the warming oven100at a predetermined time. This timer can be pre-set. However, it also can be configured for user adjustability. Regardless of which type of controller150is selected, all models can desirably incorporate a movable member114sense switch that can remove or adjust power from the plurality of heating elements122and the air circulator130, specifically the fan132, while the heat insulating material108can facilitate preserving the warm air inside the chamber104when the movable member114is in the open position, for example brief periods such as loading and unloading. Further, all circuit wiring can be done by a custom designed or other suitable wiring harness.

The selective control of the air circulator130by the controller150can occur by the selective control of a fan speed regulator133, illustrated inFIG. 7. The fan132is desirably controlled by the fan speed regulator133in order to present a low velocity flow of air across the plurality of heating elements122. The controller150can be adjusted to provide the fan with about 90 volts alternating current (VAC), which has been found to be a repeatable parameter for best results during experimentation, for example. Therefore, the controller150through selective control of the fan speed regulator133, sets the fan speed of the fan132, and thus sets the air flow, so as to enhance the facilitation of substantially even heating throughout the chamber104within the desired about 15 minute heat up time, for example. The fun speed regulator133can also be manually set with the use of a digital voltmeter (DVM) or can be set with the use of an analog voltmeter. The best perceived fan speed/air flow is a function of the alternating current (AC) input voltage to a fan motor associated with the fan132. The fan voltage range to achieve the desired fan speed is about 85 VAC to 95 VAC, with the optimal setting at 90 VAC, for example.

FIG. 9illustrates a generalized controller150for selectively controlling the operation of the warming oven100. It should be understood that the generalized controller150may represent, for example, a stand-alone computer, computer terminal, portable computing device, networked computer or computer terminal, or networked portable device. Data may be entered into the generalized controller150by the user via any suitable type of user interface158, and may be stored in a computer readable memory156, which may be any suitable type of computer readable and programmable memory. Calculations are performed by a controller/processor154, which may be any suitable type of computer processor, and may be displayed to the user on a display152, which may be any suitable type of computer display, such as a liquid crystal display (LCD) or a light emitting diode (LED) display, for example.

The controller/processor154may be associated with, or incorporated into, any suitable type of computing device, for example, a personal computer or a programmable logic controller (PLC) or an application specific integrated circuit (ASIC). The display152, the controller/processor154, the memory156, and any associated computer readable media are in communication with one another by any suitable type of data bus, as is well known in the art.

Examples of computer readable media include a magnetic recording apparatus, non-transitory computer readable storage memory, an optical disk, a magneto-optical disk, and/or a semiconductor memory (for example, RAM, ROM, etc.). Examples of magnetic recording apparatus that may be used in addition to memory156, or in place of memory156, include a hard disk device (HDD), a flexible disk (FD), and a magnetic tape (MT). Examples of the optical disk include a DVD (Digital Versatile Disc), a DVD-RAM, a CD-ROM (Compact Disc-Read Only Memory), and a CD-R (Recordable)/RW.

Referring toFIG. 10, the display152is illustrated. In addition to the display, several buttons or operational elements of the user interface158are shown. For example, device operation indicators160of the controller150are shown. Further, a process value indicator162, a set value indicator164, and user input keys166are also shown. If an analog style controller is implemented, a standalone temperature display is provided to indicate the process temperature to the user. As illustrated inFIG. 5, above the display152can be positioned a power switch168to power the warming oven100and also operation indicators170, which can indicate power and heat. It should also be noted that in additional embodiments the PID temperature controller can be replaced by an LED temperature display and a dial temperature setting potentiometer as can be utilized in conjunction with the operation indicators170and the power switch168, for example. It should be noted that the controller150and the user interface158can provide for a control arrangement to allow the user to select and set the appropriate temperature from ambient to about 180° F. (82.22° C.), for example.