Patent Publication Number: US-8975562-B2

Title: Over the range microwave safety door

Description:
BACKGROUND 
     The subject disclosure relates generally to cooking appliances, and more particularly, to microwave ovens, such as Over-the Range (OTR) microwave ovens having a safety door that prevents glass in case of breakage from falling outside. 
     An Over-the-Range (OTR) microwave oven is a home appliance that is installed on a wall surface, often in an upper space portion of a range installed in the kitchen and is used to cook using microwave radiation in a heating cavity while also exhausting cooking fumes and pollution from the cooktop below (i.e., performing a ventilation function). Because of the exhaust function of an OTR oven, the location is generally around eye level of a person cooking in a kitchen in order to ventilate any gas or fumes generated. While OTR&#39;s can be made and function very safely, some problems regarding safety can arise. 
     For example, OTR ovens are typically like most microwaves in that the door has a window within for viewing an item that is being cooked. The window on the oven is helpful for many reasons, such as viewing food to see if it is done and prevent overcooking. However, for different reasons, the glass window in the door can break, shatter or customer perceive to “explode,” which can be detrimental to health for such an event to occur at eye level and above cooking food. In particular, the door glass pieces can fall out of the door and into the food being cooked on the cooktop, user&#39;s eyes, or floor where it can be stepped on by user or a pet. Breaks in the glass can occur for multiple reasons. For example, door glass can be broken from something or someone striking it, a door design defect, or what is sometime referred to as a “spontaneous” breakage which has been sometimes attributed to impurities in the glass. In at least one case of spontaneous breakage, the door glass can fracture as a result of NiS contaminates in the glass. As homes cool at night, the glass may contract at different rates in areas having non-uniformities in composition. When the non-uniformities within the glass composition respond differently to temperature differentials, then glass within the door can unexpectedly shatter due to the created stress concentration. 
     As a result, incentives are needed for manufacturers to provide safer OTR microwave ovens with the same benefits that users continue to demand. For example, safety glass designs are needed. Therefore, the present disclosure provides apparatus and methods for improving the safety of a microwave oven. 
     BRIEF DESCRIPTION OF THE DISCLOSURE 
     Apparatus and methods are disclosed to dispose a layer of plastic in between or on one side of one or more pieces of glass within an oven door for safety. The glass is adhered to a plastic layer to prevent a cut hazard to a consumer or user of the oven. Door glass can be broken from something striking the glass, a door design defect, or spontaneous breakage, such as with NiS contaminates residing within the glass. 
     In one embodiment, an apparatus includes a magnetron that provides radiation energy, and a heating cavity comprises a cavity wall with an opening that exposes the heating cavity to the radiation from the magnetron for cooking an item therein. A safety door provides access to the heating cavity for placing the item therein and has a glass window that is at least partially transparent to see within the heating cavity. The glass window includes a first glass layer, a second glass layer and a plastic laminate bonding to at least one side of at least one of the first glass layer and the second glass layer. In certain embodiments, the plastic laminate includes biaxially-oriented polyethylene terephthalate. The door is configured to retain substantially all glass of the glass window within the door and/or within the heating cavity at all times and during any break in the glass window. 
     In another embodiment, a method is disclosed for an over-the-range (OTR) oven. A door is provided to the OTR oven that seals radiation generated from a magnetron within a heating cavity upon closing. A first glass layer is provided within the door that is at least partially transparent. A second glass layer is provided that is laterally adjacent the first glass layer within the door and closer to the heating cavity. A plastic laminate is disposed to the first glass layer in order to retain glass within the door or within the heating cavity from the first glass layer upon a break therein occurring. 
     Still other features and benefits of the present disclosure will become apparent from reading and understanding the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is now made briefly to the accompanying drawings, in which: 
         FIG. 1  is a front, perspective view of a cooking appliance such as a microwave oven in which is implemented an exemplary embodiment of a safety door; 
         FIG. 2  is a perspective view show relevant portions of a safety door for an oven according to an exemplary aspect of the present disclosure; 
         FIG. 3  is a perspective view show relevant portions of a safety door for an oven according to an exemplary aspect of the present disclosure; and 
         FIG. 4  is process flow for an oven according to an exemplary aspect of the present disclosure. 
     
    
    
     Like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated. 
     DETAILED DESCRIPTION 
     An apparatus having a safety door with a safety glass window therein is disclosed, such as an Over-the-Range (OTR) microwave. The disclosure is not limited to any one particular appliance or device, but particular reference is made to OTR microwave ovens having a safety door. The door of the OTR includes a safety glass having an added layer of plastic therein. The glass of the window is adhered to the plastic with an adhesion layer so that the glass within the door sticks to the plastic at all times. Under the stress of a fracture or break, the glass remains within the door or in the microwave cavity resulting in no harm to anything outside of the oven from the glass. 
       FIG. 1  illustrates an aspect of an exemplary oven  100 , such as an OTR microwave or the like. The oven  100  includes an outer housing  102  generally configured to permit placement of the oven  100  on a counter or secured to kitchen cabinetry or a kitchen wall. The outer housing  102  is configured with a front panel  104 , a rear wall  106 , a top wall  108 , a bottom wall  110 , and pair of opposed side walls  112 . Combined together the walls of the outer housing  102  form an interior cabinet  114 , accessed by way of a door  116  and which surrounds a heating cavity  118  and components such as a power supply  122  and an RF generation module or a magnetron  124 . 
     The heated cavity  118  also includes a cavity wall  126  that serves to separate the interior cabinet  114  into a component compartment  128  and a cooking compartment  130 , the latter is provided to subject food to radiation from the magnetron  124 . The cavity wall  126  in this example includes a top cavity wall  132 , a bottom cavity wall  134 , a rear cavity wall  136 , and a pair of opposed side cavity walls  138 . 
     The oven  100  has a controller  142  that is operatively associated with power consuming feature/functions of the oven  100 . The controller  142  can include a micro computer on a printed circuit board, which is programmed to selectively control energizing of the power consuming feature/functions. The oven  100  has a control panel  144  for receiving and operating control instructions for cooking. 
     In one embodiment, the door  116  is mounted within a door frame and has a glass window  140  located in the door  116  for viewing food in the oven cooking cavity  126 . The door  116  is adapted to retain glass within the door  116  in the event of a fracture or break occurring. For example, when a fracture occurs the glass sticks to a plastic layer that is within the door and bonded to the glass window  140 . 
     As shown in  FIG. 2 , is illustrated an exemplary aspect of a door  116 ′ for an appliance, such as an OTR microwave or other like apparatus. The door  116 ′, for example, has a front window glass  213  that is disposed on a window  140 ′ hole on the inner side of a front panel  226  of a door case  208 , which is located on the door  116 ′ of the OTR oven. An attachment, such as an aluminum tape  217  is attached to the outer rim of the front window glass  213 , and a gasket  218 , such as an electromagnetic interference (EMI) gasket contacts the front panel  226  of the door case  208  as well as to the aluminum tape  217  on the side opposite from the heating chamber and facing the door panel  226  of the front window glass  213 . The aluminum tape  217  conductively connects via the gasket  218  with the door case  208 . 
     A wire mesh sheet  219  made of stainless steel or other like material is disposed on the inner side of the front window glass  213 , and on the outer peripheral rim of the wire mesh sheet  219  is attached another adhesive  220 , such as a copper tape that contacts the aluminum tape  217 . The wire mesh sheet  219  is therefore conductively connected via the copper tape with the aluminum tape, for example. 
     A ferrite sheet  221  coming into contact with the copper tape  220  on the outer peripheral rim of the wire mesh sheet  219  is disposed in the inner rim of a window hole  209  on the outer side of a front wall of a door panel  207  of a groove in a door panel  207  on the door  116 ′ of the oven. In addition, a ferrite sheet  224  is disposed on the outside of the door panel  207  that functions as a wave absorber for absorbing electric waves of the door case  208 . Other sheets may also be implemented, but are not shown. 
     In one embodiment, a plastic layer  230 , such as a biaxially-oriented polyethylene terephthalate or other durable plastic is disposed between the door case  208  and the front window glass  213 . The plastic  230  is adhered to the glass  213  with an adhesion layer  232  that is an epoxy, glue, tape or other adherent material for bonding the plastic laminate material of the plastic  230  to a front surface of the glass  213  facing the door case  208 . The plastic layer  230  is partially transparent and enables a user to at least partially see through the safety door and into the heating cavity  118  of  FIG. 1 , for example. The plastic layer  230  therefore laminates the outside surface of the front window glass  213  and functions to retain glass within the door  116 ′. In other certain embodiments, the plastic layer  230  is adhered to the opposite side of the glass  213  with the adhesion layer  232  between the back surface of the glass  213  facing the door panel  207  and the plastic  230  to adhere the plastic. Additionally, plastic may also be adhered to both sides of the glass  213 , and thus, the disclosure is not limited one particular side or both sides of the glass  213  having a plastic layer adhered thereto. An advantage is that extreme breaks or collisions with the glass are kept from shattering to the outside of the microwave, but rather are contained within one piece that moves towards the direction of impact within the oven. The pieces of the glass may still shatter, as in the cases of tempered glass or heat strengthened glass, but instead of shattering in various directions based on the magnitude and direction of forces at impact, the glass is contained within the door regardless. 
       FIG. 3  illustrates further aspects of the safety door  305  that has a first window glass  313  and a second window glass  323  that combines as an outer and inner door window through the window hole  340 . 
     Similar to the safety door  116 ′ of  FIG. 2 , the door  305  has glass for looking into a cooking cavity that may be transparent or translucent. The glass includes the first window glass  313  and the second window glass  323  disposed on a window hole  340  on the inner side of a front panel  326  of a door case  308 , which is located on the door  305  of an oven. An attachment (e.g., Al tape  317  and  327 ) is attached to the outer rim of the first window glass  313  and the second window glass  323  respectively. At least one gasket  318 , such as an electromagnetic interference (EMI) gasket resides within the door. The gasket  318  contacts the front panel  226  of the door case  208  as well as to the aluminum taping  317  and  323 . A wire mesh sheet  319  is also disposed on the inner side of the second, inner window glass  327 , and on the outer peripheral rim of the wire mesh sheet  219  is attached another adhesive  320 . A ferrite sheet  321  contacts with the copper tape  320  on the outer peripheral rim of the wire mesh sheet  319  and is disposed in the inner rim of a window hole  309  on the outer side of a front wall of a door panel  307 . 
     A plastic laminate layer  330  is disposed on the inner portion of the first window glass  313  and the outer portion of the window glass  323 . Additional plastic layer are also envisioned and the present disclosure is not limited to only one, which is used for illustrative purposes in the figures herein. The plastic laminate  330  comprises a biaxially-oriented polyethylene terephthalate or other durable polyester film, which is used for high tensile strength, dimensional stability, transparency, gas and aroma barrier properties, electrical and mechanical insulation. 
     The first glass layer  313  has a first side  340  with a surface exposed to and facing outside the window hole  340  of the safety door  305 . The layer  313  also has a second side  342  that is adjacent and opposite the first surface of the first side  340 . At least one adhesion layer  332  is disposed to the second side  342  of the first window glass  313  in order to the plastic laminate  330 . The adhesion layer  342  alternatively is disposed on the first side  313  of the first window glass  313  in order to bond the plastic layer to the first side  313  in addition to or instead of to the second side  342  as shown in  FIG. 3 . Other adhesion layers and plastic laminate layers bonded thereby are also envisioned to be on either side of the second window glass  323  in order to provide varying degrees of stability during breakage of the first and second window glasses. Further, a second adhesion layer (not shown) may be disposed laterally to the opposite side of the plastic laminate layer  330  for adhering to the second window glass  323  in order to retain both the first glass layer  313  and the second glass layer  323  within the door  305  during any kind of break within the glass window of the door  305 . Additionally, other plastic layers may also be envisioned that are not shown in the example of  FIG. 3  or herein. For example, a plastic layer may be bonded with an adhesion layer to both or either sides of first window glass  313  and/or to both or either sides of the second window glass  323 . In other certain embodiments, the plastic layer  330  is adhered to both the first glass layer  313  and the second glass layer  323  with the adhesion layer  332  for the first glass layer  313  and another addition adhesion layer  333  at the opposite side of the plastic layer  330  for adhering to the second glass layer  323 . Additionally, plastic may also be adhered to both sides of the first glass  313  as well as the second glass layer  323 . The disclosure is not limited to any one side of the glass or combination of multiple plastic layers and glass layers within the door for providing a safety door. For example, each glass layer of the door may have a plastic layer adhered with an adhesion layer to both respective sides of the glass, as well as other configurations of plastic layers and adhesion layers with respect to each glass layer. 
     The first window glass  313  and the second window glass  323  are each partially translucent or partially transparent so that a user of the oven having the safety door  305  is able to view through into a heating cavity. The first window glass  313  and the second window glass  323  may also be transparent, or partially opaque. The glass of each window may be heat strengthened or tempered so that the glass shatters in small pieces, rather than in large sharp jagged spears. However, the disclosure is not limited to any one particular type of glass within the safety door  305 . The first window glass  313  and the second window glass  323  may refract different colors and combine to provide one type of look for the oven by having a nuanced color of one type or multiple types depending upon consumer preferences. For example, the first window glass  313  may have a blue tint and the second window glass  327  may also have a blue tint or some other shade of color to provide a different nuanced color that emanates from the microwave for an aesthetic appeal. 
     Example methodology  400  for an oven having a controller and a memory for executing the method is illustrated in  FIG. 4 . While the method is illustrated and described below as a series of acts or events, it will be appreciated that the illustrated ordering of such acts or events are not to be interpreted in a limiting sense. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. 
       FIG. 4  illustrates a method  400  for an over-the-range (OTR) oven having a safety door to retain substantially all glass within the door and/or within the oven cavities under a breaking condition or when a break or fracture occurs in order to prevent injury outside the oven. 
     At  402  a safety door is provided to the OTR oven that seals radiation generated from a magnetron within a heating cavity upon closing. 
     At  404 , a first glass layer is provided within the door that is at least partially transparent. 
     At  406 , a second glass layer is provided that is laterally adjacent the first glass layer within the door and closer to the heating cavity of the oven. 
     At  408 , a plastic laminate is disposed to the first glass layer to retain glass within the door or within the heating cavity from the first glass layer upon a break therein occurring. 
     At  410  upon a break occurring at the first glass layer, the glass of the layer is held in place within the door without having pieces fall into the microwave and/or outside of the microwave separately. At  412 , upon a break occurring at the second glass layer the glass is held or retained within the door also. 
     In one embodiment, the plastic laminate is adhered to an outside surface of the first glass layer with an adhesion layer to retain glass from falling outside the door upon a break occurring. Alternatively, the plastic laminate is adhered to the first glass layer and between the first glass layer and the second glass layer. 
     In view of the forgoing discussion, while the concepts of a safety door have been presented in connection with ovens (e.g., the oven  100  and  100 ′), implementation of these concepts can extend to other appliances. Stoves, ranges, ovens, and other devices, which may not be outfitted with radiative elements such as magnetrons to facilitate cooking and preparation of food under safe conditions. 
     The invention has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations.