Abstract:
A safety device for a microwave oven capable of improving the assembly of the microwave oven by reducing a length of a door latch and thus securing more spacious assembly space for other parts of microwave oven. The safety device for the microwave oven includes a door key movably mounted on a door of the microwave oven and having a key switch portion protruding toward the front side of the cabinet; and a plurality of switches to be turned on/off in accordance with the reception/withdrawal of the key switch portion to selectively connect a power supply with a driving circuit, and one of the plurality of switches that is arranged in the innermost position of the device chamber is operated directly by the key switch portion.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from applications for DOOR INTERLOCK APPARATUS OF A MICROWAVE OVEN earlier filed in the Korean Industrial Property Office on the 14th of January 1999 and there duly assigned Ser. No. 760/1999, and for DOOR INTERLOCK APPARATUS OF A MICROWAVE Oven earlier filed in the Korean Industrial Property Office on the 14th of January 1999 and there duly assigned Ser. No. 761/1999. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a microwave oven, and more particularly to a safety device for a microwave oven which is operated in accordance with the opening/closing status of a door of the microwave oven to selectively connect a power supply with a driving circuit. 
     2. Description of the Prior Art 
     Generally, a microwave oven is a device for cooking/warming food by using microwaves, and has the advantage that it cooks various kinds of foods within a short period of time while keeping the original texture of the foods. 
     A conventional microwave oven is shown in FIG.  1 . Referring to FIG. 1, the conventional microwave oven has a cabinet  10  which is divided into a cooking chamber  10   a  and a device chamber  10   b . The cooking chamber  10   a  receives the food to be cooked therein, and a door  30  is mounted on the front side of the cooking chamber  10   a . Various electric components  22   a ,  22   b ,  22   c ,  22   d  are arranged in the device chamber  10   b  for generating the microwaves for cooking the desired food, and a control panel  40  is formed on the front side of the device chamber  10   b.    
     However, there is the possibility that the microwave oven can be operated without the door  30  being completely closed, and the microwaves radiated into the cooking chamber  10   a  may leak outside, harming the user. In order to prevent such a dangerous use, a safety device is essentially required for the microwave oven to selectively control the operation of the microwave oven by detecting the opening/closing status of the door  30 . FIG. 2A shows the safety device of a conventional microwave oven. 
     Referring to FIG. 2A, the safety device of the subject conventional microwave oven includes a first switch  41 , a second switch  42 , and a third switch  43 , all of which are formed on a door latch  12  of the device chamber  10   b , and a door key  37  having a pair of key switch portions  37   a  and  37   b  formed on the door  30  for operating the contact points of the first, second, and third switches  41 , 42 , and  43 . 
     The first switch  41  is arranged near the end of a first guide portion  13   a , and the second and third switches  42  and  43  are arranged near the end of a second guide portion  13   b . Between the second guide portion  13   b  and the third switch  43 , a switch lever  44  is disposed such that it is pivoted on a hinge axis  44   a . The first, second, and third switches  41 ,  42 , and  43  selectively connect a power supply (not shown) with a driving circuit (not shown) of the microwave oven. 
     As the user closes the door  30 , the pair of key switch portions  37   a  and  37   b  of the door key  37  are inserted into a pair of insert holes  12   a  and  12   b  of the door latch  12 , and are guided along the guide portions  13   a  and  13   b , respectively. Accordingly, by the second key switch portion  37   b , the switch lever  44  is pivoted, and the contact point of the third switch  43  is operated. When the door  30  is completely closed, as shown in FIG. 2B, the pair of key switch portions  37   a  and  37   b  are moved downward by a spring  37   c , so that the contact points of the first and second switches  41  and  42  are operated. Only when the contact points of the first, second, and third switches  41 ,  42 , and  43  are operated, the power supply (not shown) is connected to the driving circuit (not shown). 
     In the event that the door  30  is incompletely closed and any contact point of the first, second, and third switches  41 ,  42 , and  43  is not in operation, the power supply (not shown) can not make contact with the driving circuit (not shown), and as a result, the microwave oven can not be turned on. 
     According to the safety device of the subject conventional microwave oven, however, the third switch  43 , which is located in the innermost part of the device chamber  10   b , is positioned to be operated indirectly via the switch lever  44 . Therefore, a space for the switch lever  44  between the second key switch portion  37   b  and the third switch  43  is needed, and the length L of the door latch  12  is lengthened. 
     As the length L of the door latch  14  is lengthened, the total available space in the device chamber  10   b  is relatively reduced, and the space for the various operational components  22   a ,  22   b ,  22   c , and  22   d  is reduced. Accordingly, the efficient assembly of the microwave oven is deteriorated. 
     Further, according to the safety device of the conventional microwave oven, as shown in FIGS. 2A and 2B, wiring pins  41   a  and  42   a  of the first and second switches  41  and  42  are extended inward in the device chamber  10   b , while the wiring pin  43   a  of the third switch  43  is extended toward the door  30 . Accordingly, the wiring structure becomes complex, and the assembly of the microwave oven is deteriorated due to the complex wiring process. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed to overcome the above-mentioned problems of the referenced prior art, and accordingly, it is a first object of the present invention to provide a safety device for a microwave oven capable of improving the assembly of the microwave oven by reducing the space needed for a door latch and thus securing more assembly space for other component parts. 
     A second object of the present invention is to provide a safety device for a microwave oven which simplifies the wiring process and structure of switches, by extending the wiring pins of the switches in substantially the same direction. 
     The first object is accomplished by a safety device for a microwave oven including a door, a cabinet having a cooking chamber and a device chamber, a power supply, and a driving circuit according to the present invention, comprising: a door key movably mounted on the door of the microwave oven and having a key switch portion protruding toward the front side of the cabinet; and a plurality of switches turned on/off in accordance with drawing/withdrawing of the key switch portion, to selectively connect the power supply with the driving circuit, in which one of the plurality of switches, that is arranged in the innermost position of the device chamber, is operated directly by the key switch portion. 
     Further, the second object is accomplished by a safety deice for a microwave oven including a door, a cabinet having a cooking chamber and a device chamber, a power supply, and a driving circuit according to the present invention, comprising: a door key movably mounted on the door of the microwave oven and having a key switch portion protruding toward the front side of the cabinet; and a plurality of switches to be turned on/off in accordance with the drawing/withdrawing of the key switch portion to selectively connect the power supply with the driving circuit, in which wiring pins of the plurality of switches are extended either in a direction of the vertical line of the door key, or inward the device chamber from the vertical line of the door key. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a partially cutaway perspective view of a conventional microwave oven; 
     FIG. 2A is a sectional view for showing the main portion of a safety device of a conventional microwave oven, in which a door of a microwave oven is in an open state; 
     FIG. 2B is a sectional view for showing the main portion of the safety device of the conventional microwave oven in which the door of a microwave oven is in a closed state; 
     FIG. 3A is a sectional view for showing the main portion of a safety device according to a first preferred embodiment of the present invention, in which a door of a microwave oven is in an open state; 
     FIG. 3B is a sectional view for showing the main portion of the safety device according to the first preferred embodiment of the present invention, in which the door of the microwave oven is in a closed state; 
     FIG. 4A is a sectional view for showing the main portion of a safety device according to a second preferred embodiment of the present invention, in which a door of a microwave oven is in is an open state; and 
     FIG. 4B is a sectional view for showing the main portion of the safety device according to the second preferred embodiment of the present invention, in which the door of the microwave oven is in a closed state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     FIGS. 3A and 3B show a safety device of a microwave oven according to a first preferred embodiment of the present invention. 
     Referring to FIGS. 3A and 3B, the safety device of the microwave oven according to the first preferred embodiment of the present invention includes a door key  137 , and first, second, and third switches  141 ,  142 , and  143 . 
     The door key  137  is biased downward by a spring  137   c , and is movably mounted on a door  130  of the microwave oven. The door key  137  has first and second switch portions  137   a  and  137   b  which are protruded toward the front side of the cabinet  10  of the microwave oven. 
     The first, second, and third switches  141 ,  142 , and  143  are formed on a door latch  112 , which is arranged in the device chamber  10   b  of the microwave oven, and are turned on/off by the first and second key switch portions  137   a  and  137   b , to selectively connect the power supply (not shown) of the microwave oven with a driving circuit (not shown). 
     On the door latch  112 , insert holes  112   a  and  112   b  are formed to permit the drawing/withdrawing of the key switch portions  137   a  and  137   b  therethrough, and first and second guide portions  113   a  and  113   b  are also formed on the door latch  112  to guide the movement of the first and second key switch portions  137   a  and  137   b.    
     The first switch  141  is arranged near the end of the first guide portion  113   a , while the second and third switches  142  and  143  are arranged near the end of the second guide portion  113   b.    
     In such a situation, the second switch  142  which is positioned at the lowest portion of the door latch  112 , and the third switch  143  which is positioned in the innermost portion of the device chamber  10   b , are arranged to face each other by having a space therebetween. Here, the space between the second and third switches  142  and  143  is determined such that the second and third operational portions  142   b  and  143   b  of the second and third switches  142  and  143  are simultaneously pushed by the second switch portion  137   b.    
     Meanwhile, it is preferable that the key switch portions  137   a  and  137   b  be slanted at a certain angle with respect to the vertical line of the door key  137  to smoothly operate the door key  137 . Accordingly, the second and third switches  142  and  143  are slanted at the same angle as the first and second key switch portions  137   a  and  137   b.    
     Further, it is preferable that the space defined between the second and third switches  142  and  143  is formed such that the upper space is larger than the lower space. 
     More specifically, the slanted angle “c” for the first and second key switch portions  137   a  and  137   b  with respect to the vertical line of the door key  137 , is set at a range of approximately from 25° to 35° with the most preferable value of 30°. Further, the slanted angle “b” for the second switch  142  with respect to the vertical line of the door key  137 , is set at a range of approximately from 33° to 39°, with the most preferable value of 36°, and the slanted angle “a” for the third switch  143  with respect to the vertical line of the door key  137 , is set at a range of approximately from 27° to 33°, with the most preferable value of 30°. 
     It is further preferable that the wiring pins  141   a ,  142   a ,  143   a  of the first, second, and third switches  141 ,  142 , and  143  are either extended along the vertical line of the door key  137 , or extended inward the device chamber  10   b  from the vertical line of the door key  137 . 
     The safety device of the microwave oven according to the first preferred embodiment of the present invention constructed as above is operated as follows: 
     As the door  130  is closed, the pair of key switch portions  137   a  and  137   b  extended from the door key  137  are inserted into the insert holes  112   a  and  112   b  of the door latch  112 , and are guided along the first and second guide portions  113   a  and  113   b.    
     As the door is completely closed, the first key switch portion  137   a  pushes the first operational portion  141   b  of the first switch  141 , while the second key switch portion  137   b  is inserted between the second and third switches  142  and  143 . 
     Accordingly, operational portions  142   b  and  143   b  of the second and third switches  142  and  143  are pushed simultaneously by the second key switch portion  137   b , so that the power supply and the driving circuit of the microwave oven make contact with each other, and then the user can use the microwave oven. 
     In the event that the door  130  is incompletely closed and any operational portion of the first, second, and third switches  141 ,  142 , and  143  is not pushed, the power supply can not make contact with the driving circuit, so that the microwave oven is inoperable. 
     Further, FIGS. 4A and 4B show the safety device for a microwave oven according to the second preferred embodiment of the present invention. 
     Referring to FIGS. 4A and 4B, the safety device for the microwave oven according to the second preferred embodiment of the present invention includes a door key  237 , a switch lever  260 , and first, second, and third switches  241 ,  242 , and  243 . 
     The door key  237  is biased downward by a spring  237   c , and is movably mounted on a door  230  of the microwave oven. Further, the door key  237  has first and second key switch portions  237   a  and  237   b  protruded toward the front side of the cabinet  10  of the microwave oven. 
     The first, second, and third switches  241 , 242 , and  243  are formed on a door latch  212  which is positioned in the device chamber  10   b  of the microwave oven, and are turned on/off by the first and second key switch portions  237   a  and  237   b , to selectively connect a power supply (not shown) with a driving circuit (not shown). 
     On the door latch  212 , insert holes  212   a  and  212   b  are formed to permit the drawing/withdrawing of the key switch portions  237   a  and  237   b  therethrough, and further, first and second guide portions  213   a  and  213   b  are formed on the door latch  212  to guide the movement of the key switch portions  237   a  and  237   b , respectively. 
     The first switch  241  is arranged near the end of the first guide portion  213   a , while the second and third switches  242  and  243  are arranged near the end of the second guide portion  213   b . Between the second and third switches  242  and  243 , a switch lever  260  is disposed such that it is pivoted on a hinge axis  260   a.    
     Here, the second switch  242  which is arranged at the lowest portion of the door latch  212 , and the third switch  243  which is arranged in the innermost position of the device chamber  10   b , are spaced from each other at a certain distance that the third operational portion  243   b  of the third switch  243  is pushed directly by the second key switch  237   b  while the second operational portion  242   b  of the second switch  242  is pushed indirectly by the second key switch  237   b  via the switch lever  260 , when the second key switch portion  237   b  is inserted between the second and third switches  242  and  243 . 
     Further, for the smoother operation of the door key  237 , it is preferable that the first and second key switch portions  237   a  and  237   b  are slanted at a certain angle with respect to the vertical line of the door key  237 , and it is accordingly preferable that the second and third switches  242  and  243  are slanted at the same angle as the first and second key switch portions  237   a  and  237   b  are. 
     More specifically, it is preferable that the slanted angle “c” for the first and second key switch portions  237   a  and  237   b  with respect to the vertical line of the door key  237 , is set at a range of approximately from 32° to 42° with the most preferable value of 37°. Further, the slanted angle “b” for the second switch  242  with respect to the vertical line of the door key  237 , is set at a range of approximately from 55° to 65°, with the most preferable value of 60°, and the slanted angle “a” for the third switch  243  with respect to the vertical line of the door key  237 , is set at a range of approximately from 25° to 35°, with the most preferable value of 30°. 
     It is further preferable that the wiring pins  241   a ,  242   a , and  243   a  of the first, second, and third switches  241 ,  242 , and  243  are either extended along the vertical line of the door key  237 , or extended inward the device chamber  10   b  from the vertical line of the door key  237 . 
     The safety device for the microwave oven constructed as above according to the second preferred embodiment of the present invention is operated as follows: 
     As the door  230  is closed, the first and second key switch portions  237   a  and  237   b  extended from the door key  237  are inserted into the insert holes  212   a  and  212   b  of the door latch  212 , and are guided along the first and second guide portions  213   a  and  213   b , respectively. 
     As the door  230  is completely closed, the first key switch portion  237   a  pushes the first operational portion  241   b  of the first switch  241 , while the second switch portion  237   b  is inserted between the second and third switches  242  and  243 . 
     Accordingly, a third operational portion  243   b  of the third switch  243  is pushed directly by the second key switch portion  237   b , while the switch lever  260  is pivoted on the hinge axis  260   a  downwardly. 
     Accordingly, a second operational portion  242   b  of the second switch  242  is pushed indirectly by the second key switch portion  237   b  via the switch lever  260 . Therefore, the power supply is connected with the driving circuit, and the user can operate the microwave oven. 
     In the event that the door  230  is incompletely closed and any operational portion of the first, second, and third switches  241 ,  242 , and  243  is not pushed, the power supply is not connected with the driving circuit, and accordingly, the microwave oven is not operated. 
     As described above, in the safety device for a microwave oven according to the present invention, the third switches  143  and  243 , which are arranged in the most inner position of the device chamber  10   b , are operated directly by the second key switch portions  137   b  and  237   b  of the door keys  137  and  237 , respectively. 
     Accordingly, the switch lever  44  of the conventional safety device of the microwave oven is no longer required between the key switch portions  137   b  and  237   b  and the third switches  143  and  243 , so that the lengths L′ and L″ of the door latches  112  and  212  are shortened, respectively. Since the lengths L′ and L″ of the door latch  14  are shortened, the total available space in the device chamber  10   b  is enlarged, and the assembly space for the other electric component parts is enlarged. Also, the assembly of the microwave oven improves. 
     Further, in the safety device for the microwave oven according to the present invention, the wiring pins  141   a ,  142   a ,  143   a ,  241   a ,  242   a , and  243   a  of the first, second, and third switches  141 ,  142 ,  143 ,  241 ,  242 , and  243  are at least extended along the vertical line of the door keys  137  and  237 , or extended inward the device chamber  10   b  from the vertical line of the door keys  137  and  237 . 
     Accordingly, since the wiring pins  141   a ,  142   a ,  143   a ,  241   a ,  242   a , and  243   a  of the first, second, and third switches  141 ,  142 ,  143 ,  241 ,  242 , and  243  are extended substantially in the same direction, the wiring process and structure are much more simplified, and the assembly of the microwave oven is much improved. 
     Further, in the safety device for the microwave oven according to the first preferred embodiment of the present invention, the operational portions  142   b  and  143   b  of the second and third switches  142  and  143  are pushed by the second key switch portion  137   b , simultaneously. 
     Accordingly, additional parts which were required in the safety device for the subject conventional microwave oven such as the switch lever  44 , etc. are no longer required, so that the structure of the safety device is simplified, and due to the reduced number of parts, the assembly of the microwave oven is vastly improved and the manufacturing cost is significantly reduced. 
     As stated above, preferred embodiments of the present invention are shown and described. Although the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to this preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.