Patent Abstract:
A sensor assembly is provided for an automatic drying machine having a rotatable drum containing a load of wet clothes to be dried wherein at least one sensing element is disposed on a surface of an elongated sensor body and is exposed to inside of the drum so as to make contact with the wet clothes. The sensor body is secured directly to a bulkhead having an air outlet opening and is provided at the air outlet opening for effective engagement with the wet clothes.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of the Korean Application No. P2003-0026744 filed on Apr. 28, 2003, which is hereby incorporated by reference as is fully set forth herein. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to dryers, and more particularly, to a sensor assembly for determining dryness of a load of wet clothes being dried in an automatic dryer. 
   2. Background of the Related Art 
   The automatic dryer dries a wet state drying object (for an example, clothes and the like) having washing thereof completed, automatically. In general, the dryers, having a system for supplying hot air heated by a heater to a drum for drying, are sorted as exhaust type dryers and condensing type dryers. 
   The exhaust type dryer dries the drying object by discharging air having carried out the drying to have a low temperature and to become humid to an exterior, drawing fresh airs heating the air, and supplying the heated air to the drum. 
   The condensing type dryer dries the drying object by condensing the air having carried out the drying to have a low temperature and to become humid, for removing moisture therefrom, heating, and supplying to the drum again. 
   In general, both the exhaust, and condensing type dryers employ an operating method in which a heater and a blower are operated for a preset time period for drying the drying object in the drum. However, the dryers having employed the method have the following problems. 
   The drying of different kinds of drying objects having different materials, weights, volumes, moisture contents, and the like by the same operating method for the preset time period causes to fail to provide an optimal drying performance, always. That is, there can be an occasion when drying of some of the drying objects is not finished even if operation of the dryer is finished, when re-operation of the dryer is required. 
   The failure in constant provision of the optimal drying performance leads the dryer set to operate for a longer time period, to require a much drying time period and a long time operation of the heater, and blower motor more than required, to result in waste of energy. 
   Taking the foregoing problems into account, introduction of a feed back system is required, in which the dryer is operated after dryness or humidity of laundry is sensed and provided to a controller during drying, an optimal operation condition is calculated based on information obtained by sensing, and setting of a heating quantity of the heater, a blowing rate of the blower, a rotation speed of the drum, an operation time period, and the like are changed. 
   In order to introduce the foregoing feed back system, a sensor is required for sensing dryness or humidity of the laundry. However, since the drum keeps rotating during operation, it is required to fit the sensor such that a stable exchange of electrical signals between the sensor and the controller is possible. Consequently, for the introduction of the feed back system, a solution for a sensor fitting structure is also required, as well. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to a sensor assembly for an automatic dryer that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
   An object of the present invention designed owing to the foregoing requirements lies on providing a sensor assembly for an automatic dryer that can provide a structure in which a sensor is fitted to an inside of the dryer for sensing dryness or humidity of laundry and transmitting to a controller during drying of the laundry so that a feed back system can be introduced to the dryer. 
   Another object of the present invention is to provide a sensor assembly which can be assembled easily, and replaceable at a low cost. 
   Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
   To achieve these objects and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a sensor assembly for an automatic dryer having a rotatable drum containing a load of wet clothes to be dried includes a bulkhead having an air outlet opening that exhausts humidified air from the drum, an electrical non-conductive sensor body secured directly to the bulkhead and positioned so as to cover a portion of the air outlet opening, and at least one sensing element disposed on a first surface of the sensor body. The sensing element is exposed to inside of the drum so as to make contact with the wet clothes for measuring moisture content and temperature of the clothes. 
   The sensor body described above includes an extension member extended from a second surface (opposite to the first surface exposed to the inside of the drum) of the sensor body. Also, a first mounting bracket having an aperture provided thereon is extended from the bulkhead and the extension member is inserted into the aperture for slip fit engagement with the first mounting bracket. The extension member of the sensor body may include a detent which engages with the first mounting bracket to prevent the extension member from being disengaging from the first mounting bracket. 
   In addition, a first end of the sensor body may include a first screw hole adapted to receive a first screw for securing the first end directly to the bulkhead, and a second end of the sensor body may include a second screw hole adapted to receive a second screw for securing the second end to a mounting bracket extended from the bulkhead. Alternatively, the first end of the sensor body may include a slot adapted to receive a thin portion of the bulkhead for securing the first end to the thin portion of the bulkhead. 
   The sensor assembly described above further includes a perforated air outlet grill secured to the bulkhead where the air outlet grill covers the remaining portion of the air outlet opening. The air outlet grill may include a caved channel formed on a lower circumferential edge of the air outlet grill for receiving the sensor body where the first surface of the sensor body is slopped away from a surface of the air outlet grill to thereby project into the inside of the drum for improved contact with the wet clothes. In addition, the sensor body includes a groove formed on an upper edge of the first surface and the air outlet grill includes a ridge that engages with the groove for pressing down the upper edge of the first surface so as to prevent disengagement of the sensor body from the caved channel of the air outlet grill. 
   In further aspect of the present invention, an automatic dryer comprises a cabinet, a drum rotatably provided in the cabinet for containing a load of wet clothes to be dried, a rear bulkhead comprising an air inlet opening that exhausts dry air into the drum, and a front bulkhead comprising an air outlet opening that exhausts humidified air from the drum. The automatic dryer further comprises an electrically non-conductive sensor body secured directly to the front bulkhead and positioned so as to cover a portion of the air outlet opening, at least one sensing element disposed on a first surface of the sensor which is exposed to inside of the drum so as to make contact with the wet clothes, and a perforated air outlet grill being rigidly secured to the from the front bulkhead for covering the remaining portion of the air outlet opening. 
   The sensor body included in the automatic dryer may include an extension member extended from a second surface (opposite to the first surface) of the sensory body. A first mounting bracket having an aperture formed thereon is extended from the front bulkhead so that the extension member can be inserted into the aperture for slip engagement with the first mounting bracket. The extension member of the sensor body may include a detent which engages with the first mounting bracket to prevent the extension member from being disengaged from the first mounting bracket. 
   In addition, a first end of the sensor body may include a first screw hole adapted to receive a first screw for securing the first end directly to the bulkhead, and a second end of the sensor body may include a second screw hole adapted to receive a second screw for securing the second end to a mounting bracket extended from the bulkhead. Alternatively, the first end of the sensor body may include a slot adapted to receive a thin portion of the bulkhead for securing the first end to the thin portion of the bulkhead. 
   The sensor body may further include a groove formed on an upper edge of the first surface and the air outlet grill may include a ridge that engages with the groove for pressing down the upper edge of the first surface so as to prevent disengagement of the sensory body from the caved channel of the air outlet grill. The first surface of the sensor body is slopped away from the surface of the air outlet grill to thereby project into the inside of the drum for improved contact with the wet clothes. 
   It is to be understood that both the foregoing description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings; 
       FIG. 1  illustrates a perspective view with a partial cut away view for showing an inside of a dryer in accordance with a preferred embodiment of the present invention; 
       FIG. 2  illustrates a perspective disassembled view showing assembly of some of components of the dryer in accordance with a preferred embodiment of the present invention; 
       FIGS. 3 and 4  illustrate perspective views each seen from an inside of a drum showing the sensor and the air outlet grill in  FIG. 2  respectively mounted to a front bulkhead; 
       FIG. 5  illustrates a perspective disassembled partial view seen from an outside of a drum showing mounting of a sensor in accordance with a first preferred embodiment of the present invention; 
       FIG. 6  illustrates a perspective view showing the sensor mounted; 
       FIGS. 7A ,  7 B, and  7 C illustrate cross-sections showing different embodiments of the first fastening means; 
       FIG. 8  illustrates a perspective view showing a sensor in accordance with a second preferred embodiment of the present invention; 
       FIGS. 9 and 10  illustrate perspective views each seen from an inside of a drum showing the sensor in  FIG. 8  mounted on a front bulkhead; 
       FIG. 11  illustrates a perspective view showing a sensor in accordance with a third preferred embodiment of the present invention; 
       FIG. 12  illustrates a perspective view seen from an inside of a drum showing the sensor in  FIG. 11  mounted on a front bulkhead; 
       FIG. 13  illustrates a perspective view seen from an inside of a drum showing a sensor another embodiment of the second fastening means applied thereto mounted on a front bulkhead, together with an air outlet grill, in accordance with a first, second, or third preferred embodiment of the present invention; 
       FIG. 14  illustrates a section showing a sensor mounted in accordance with a fourth preferred embodiment of the present invention; and 
       FIG. 15  illustrates a perspective view showing the sensor in  FIG. 14  being mounted. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     FIG. 1  illustrates a perspective view with a partial cut away view for showing an inside of a dryer in accordance with a preferred embodiment of the present invention, and  FIG. 2  illustrates a perspective disassembled view showing assembly of some of components of the dryer in accordance with a preferred embodiment of the present invention. 
   Referring to  FIGS. 1 and 2 , a drum  20  is rotatably provided to a cabinet  10  of a dryer shown in FIG.  1 . For this, a belt  40  connects a motor  30  and the drum  20  provided to an inside of the cabinet  10 . According to this system, since the belt  40  transmits a power from the motor  30  to the drum  20 , the drum  20  can rotate inside of the cabinet  10 . 
   The drum  20  has tumbling ribs  25  provided to an inside circumferential surface thereof for lifting and dropping the drying objects held inside of the drum  20  when the drum rotates. 
   Opposite ends of the drum  20  are opened, to which a front bulkhead  100  and a rear bulkhead  50  are provided adjacently. The front bulkhead  100  and the rear bulkhead  50  are fixed to the cabinet  10  or a supporting member provided to an inside of the cabinet  10 , and not rotatable with the drum  20 . 
   The rear bulkhead  50  has an air inlet opening  55  for introduction of hot air heated by the heater (not shown) into the drum  20 . As shown in  FIG. 2 , the front bulkhead  100  has two openings; one for exhausting air from an inside of the drum  20 , and the other for serving as an introduction opening for introduction/taking drying objects into/out of the drum  20  through the opening when a door (not shown) of the dryer is opened. The two openings are divided by a dividing member  150 . For convenience of description, the opening serving as the introduction opening is called as a first opening  110 , and the opening serving as an air exhaust opening is called as an air outlet opening  120 . 
   Provided to the air outlet opening is an air outlet grill  300  for prevention of the drying objects held inside of the drum  20  from escaping therethrough, and a sensor  200  for measuring information on an inside of the drum  20 , for an example, humidity or temperature of the drying object. The air outlet grill  300  and the sensor  200 , provided to the air outlet opening  120 , are mounted on and fixed to the front bulkhead  100 , respectively. 
     FIGS. 3 and 4  illustrate perspective views each seen from an inside of a drum  20  showing the sensor  200  and the air outlet grill  300  in  FIG. 2  respectively mounted to an air outlet opening  120  in a front bulkhead  100 , as an example. As shown, the sensor  200  is mounted to an inside circumference of the front bulkhead  100  to occupy an area of the air outlet opening  120 , and the air outlet grill  300  is mounted on the front bulkhead  100  after the sensor  200  is mounted on the front bulkhead  100  so that the air outlet grill  300  covers an entire remained area of the air outlet opening  120  excluding a portion of area occupied by the sensor  200 . Meanwhile, the sensor  200  and the air outlet grill  300  respectively mounted to the front bulkhead  100  are not attached or fixed to each other. 
   The sensor  200  thus mounted includes electrically non-conductive sensor body  210 , a sensing element, and fastening means. The sensing element, provided for sensing a temperature and humidity of the drying object, includes, for an example, an electrode  215  for coming into direct contact with, for an example, air or the drying object inside of the drum  20  and measuring moisture content of the drying object. The sensing element is provided to a surface of the sensor body  210  facing the inside of the drum  20  for easy and direct contact with air or the drying object inside of the drum  20 . In the meantime, the fastening means, provided for mounting the sensor  200  on the front bulkhead  100 , provides a variety of embodiments of the sensor mounting structure as the fastening means has a variety of systems. In the meantime,  FIGS. 3 and 4  are exemplary, and do not limit the structure of the fastening means of the present invention. 
   The air outlet grill  300  has a grill structure in which a plurality of members are crossed for free pass of air. As shown in  FIG. 3 , the air outlet grill  300  has a caved channel  310  formed in a form of a channel in a part of an outer circumferential surface for preventing interference with the sensor  200  when the air outlet grill  300  is provided to the air outlet opening  120 . 
   The air outlet grill  300  also includes air outlet grill fastening means for easy mounting of the air outlet grill  300  to the front bulkhead  100 . In  FIGS. 3 and 4 , one example of the air outlet grill fastening means, a plurality of first pass through holes  320  are shown. In a case the first pass through holes  320  are provided to the air outlet grill  300 , second pass through holes  160  in correspondence to the first pass through holes  320  are provided to the front bulkhead  100 . The first and second pass through holes  320  and  160  are screw holes. When the correspondent first and second pass through holes  320  and  160  are provided to the air outlet grill  300  and the front bulkhead  100  respectively, the air outlet grill  300  can be fastened to the front bulkhead  100  with screws or the like firmly, after the air outlet grill  300  is mounted on the front bulkhead  100  to cover the air outlet opening  120 , as shown in  FIG. 4 , once the air outlet grill  300  is fastened, the sensor  200  and the air outlet grill  300  can be respectively fastened to the front bulkhead  100  independently, because the caved channel  310  in the air outlet grill  300  secure a space for the sensor  200 . 
   However, the air outlet grill fastening means is not limited to the first pass through holes  320  shown in  FIGS. 3 and 4 . A plurality of hooks on the air outlet grill  300  and hook holes in the front bulkhead  100  for receiving the hooks may work as the fastening means. Therefore, the air outlet grill fastening means is not limited to the first pass through holes  320 , but any structure that can fasten the air outlet grill  300  to the front bulkhead  100  is adequate for the air outlet grill fastening means. 
   A variety of embodiments of a structure in which the sensor  200  is mounted to the front bulkhead  100  depending on a variety of the fastening means provided to the sensor  200  will be described in more detail, with reference to drawings. 
     FIG. 5  illustrates a perspective disassembled partial view seen from an outside of the drum  20  showing mounting of the sensor  200  inclusive of first fastening means on the front bulkhead  100  in accordance with a first preferred embodiment of the present invention. 
   Referring to  FIG. 5 , the first fastening means includes an ‘L’ extension member provided to one surface of the sensor body  210 , for an example, a surface opposite to a surface the electrode is mounted thereon. The extension member  220  provided as the first fastening means is fastened to the front bulkhead  100  by means of elastic force and friction force. 
     FIG. 5  shows an example of an aperture  135  provided to a first mounting bracket  130  extended from the front bulkhead  100  vertical to an inside circumferential surface of the front bulkhead  100 , i.e., a surface the sensor  200  is mounted thereon. In more detail, an example is shown, in which the extension member  220  includes a vertical part  221  projected from the sensor body  210 , and a horizontal part  225  bent in one direction at an end of the vertical part  221 . For reference, the unexplained reference symbol  216  denote terminals of the electrode  215  shown in  FIGS. 3 and 4 . 
   The sensor  200  having the foregoing extension member  220  is fastened by inserting the extension member  220  in the aperture  135  and pushing in a direction of the horizontal part  225 . That is, the extension member  220  is inserted into the aperture  135  for slip fit engagement with the first mounting bracket  130 . On doing so, the first mounting bracket  130  is inserted between the horizontal part  225  of the extension member  220  and the sensor body  210  tightly as shown in FIGS.  6 ˜ 7 B. 
   Referring to  FIG. 6 , according to this operation, the sensor  200  is securely fastened to the front bulkhead  100  by an elastic force of the extension member  220 , and friction forces at surfaces the extension member  220  and the first mounting bracket  130  are in contact, and the first mounting bracket  130  and the sensor body  210  are in contact. For the secure fastening of the sensor  200 , it is preferable that a thickness of the first mounting bracket  130  is equal to, or slightly greater than a distance between the horizontal part  225  of the extension member  220  and the sensor body  210 . 
   The present invention also provides a structure for preventing the sensor  200  once fastened to the front bulkhead  100  from being disengaged from the front bulkhead  100  easily due to vibration and the like. Referring to  FIG. 7B , first and second detents  226  and  131  are provided to the extension member  220  and the first mounting bracket  130  for prevention of disengagement. The first detent  226  provided to the extension member  220  is projected from the horizontal part  225  of the extension member  220  toward the sensor body  210 . The second detent  131  is projected from the first mounting bracket  130  toward the horizontal part  225  so as to be positioned between the vertical part  221  of the extension member  220  and the first detent  226 . Once the first and second detents  226  and  131  are provided, movement of the sensor  200  is prevented by the first and second detents  226  and  131  even if an external force, such as vibration or the like, is occurred after the sensor  200  is mounted. In the meantime, as another embodiment, a structure may be possible in which at least one projection and recess for receiving the projection are provided to the extension member  220  and the first mounting bracket  130 . 
   In the meantime, the first fastening means of the sensor  200  is not limited to above embodiment. That is, as shown in  FIG. 7C , the first fastening means may include two extension members  220 , and a wedge form at an end of each of the extension members  220  for easy insertion of the extension member  220  into the aperture  135 . As shown in  FIG. 7C , the fastening means permits firm fastening of the sensor  200  as the extension members  220  are elastically deformed toward a center of the aperture  135  when the extension member is inserted into the aperture  135  for slip fit engagement with the first mounting bracket  130 , and restored again when the wedge forms pass the aperture  135 . 
   Though the first fastening means can be fastened to the aperture  135  in the first mounting bracket  130  extended from the front bulkhead  100 , the first fastening means may be fastened to the front bulkhead  100 , directly. If an aperture is formed in an inside circumferential surface of the front bulkhead  100 , and the first fastening means is provided to a surface of the sensor  200  which is brought into contact with the inside circumferential surface of the front bulkhead  100 , according to a principle as above, the sensor  200  can be mounted on the front bulkhead  100 . Therefore, positions of the first fastening means illustrated in  FIGS. 5 and 6  are exemplary, and do not limit the position of the first fastening means in the present invention. 
   In the meantime, referring to  FIGS. 5 and 6 , the sensor  200  is provided with second fastening means, further. The second fastening means is provided for maintaining a fastened state more firmly after the sensor  200  is fastened by using the first fastening means.  FIGS. 5 and 6  illustrate examples of a first screw hole  230  provided to one end of the sensor  200  as the second fastening means. In a case the first screw hole  230  is provided to the sensor  200  thus, a second screw hole  141  is provided to the front bulkhead  100  in correspondence to the first screw hole  230 . In this instance, as shown in  FIGS. 5 and 6 , the second screw hole  141  is provided to a second mounting bracket  140  extended from the front bulkhead  100  vertical to an inside circumferential surface of the front bulkhead  100 , a surface the sensor  200  is mounted thereon. 
   The first and second screw holes  230  and  141  are formed at positions the first and second screw holes  230  and  141  meet when the sensor  200  is mounted on the front bulkhead  100 . Then, since the first and second screw hole  141  form a continuous screw hole, a screw can be fastened to the one screw hole the first and second screw holes  141  form after the sensor  200  is fastened by using the first fastening means. Thus, the sensor  200  can be mounted to the front bulkhead  100 , more firmly. 
   After the sensor  200  is mounted on the bulkhead  100  by using the first and the second fastening means, the air outlet grill  300  is mounted on the front bulkhead  100 . Referring to  FIG. 3 , when it is intended to mount the air outlet grill  300 , the first pass through holes  320  in the air outlet grill  300  and the second pass through holes  160  in the front bulkhead  100  are aligned, and fastens with fastening members, such as screws. One of the second pass through holes  160  can be provided to the second mounting bracket  140  as shown in  FIGS. 5 and 6 . 
   In the meantime, FIGS.  8 ˜ 10  illustrate a second embodiment of the present invention, which will be described in detail, with reference to the drawings. 
   The sensor  200  in the embodiment illustrated in FIGS.  8 ˜ 10  includes fastening means having second fastening means and third fastening means. As shown in FIGS.  8 ˜ 10 , the second fastening means has a first screw hole  230  in one side part of the sensor  200 , which is identical to an example described in association with  FIGS. 5 and 6 , and description of which will be omitted. The third fastening means will be described, hereafter. 
   The third fastening means  200  includes a third screw hole  240  provided to the other end of the sensor  200 , i.e., an end opposite to an end the first screw hole  230  is provided thereto. While the first screw hole  230  vertically passes through a surface the electrodes  215  are provided thereto and is in communication with the second screw hole  141  in the second mounting bracket  140  extended in a vertical direction from the inside circumferential surface of the front bulkhead  100 , i.e., the surface the sensor  200  is mounted thereon, the third screw hole  240  is in communication with a fourth screw hole  170  which vertically passes through the surface the sensor  200  is mounted thereon and is provided to the inside circumferential surface of the front bulkhead  100  as shown in FIG.  9 . 
   Once the sensor  200  has the second screw hole  141  and the third screw hole  240 , opposite ends of the sensor  200  can be respectively fastened to the second mounting bracket  140  extended for the front bulkhead  100  and the inside circumferential surface of the front bulkhead  100  with screws or the like, firmly. 
   In this embodiment too, the air outlet grill  300  is mounted to the front bulkhead  100  so as to cover the air outlet opening  120  after the sensor  200  is mounted, of which detailed description will be omitted as the description is the same with before. 
     FIGS. 11 and 12  illustrate a third preferred embodiment of the present invention, which will be described in detail with reference to the drawings. 
   In the embodiment illustrated in  FIGS. 11 and 12 , the sensor  200  includes fastening means having second fastening means and third fastening means. The second fastening means, having the first screw hole  230  provided to one side part of the sensor  200 , is identical to the embodiments described with reference to FIGS.  5 ˜ 10 , and of which description will be omitted. The third fastening means will be described. 
   In the third embodiment of the present invention, the third fastening means includes a slot  230  provided in an up and down direction in the other end of the sensor  200 , i.e., an end opposite to an end the first screw hole  230  is formed therein.  FIG. 11  or  12  illustrates an embodiment in which the slot  255  is provided to a third plate  250  extended from the other end of the sensor  200  in parallel to the inside circumferential surface of the front bulkhead  100 , i.e., a surface the sensor is mounted thereon. Once the third embodiment has the foregoing system, no separate fastening member is required for fastening the other end of the sensor  200 , which will be described. 
   After the sensor  200  is brought into contact with the front bulkhead  100 , a thin part of the front bulkhead  100 , for an example, an end of a side the slot  255  is provided thereto, is pushed up toward a corner part where the inside circumferential surface of the front bulkhead  100  and the dividing member  150  are joined. Then, as shown in  FIG. 12 , since a part of the front bulkhead  100  is inserted in the slot  255 , the sensor  200  can not move in a direction excluding a length or up and down direction of the slot  255 . It is preferable that a width of the slot  255  is equal to or slightly smaller than a thickness of the corner part where the inside circumferential surface of the front bulkhead  100  and the dividing member  150  are joined. In a state a part of the front bulkhead  100  is inserted in the slot  255 , when a screw or the like is fastened to the first screw hole  230  and the second screw hole  141 , the sensor  200  is mounted, firmly. 
   In the third embodiment too, the air outlet grill  300  is mounted to the front bulkhead  100  after the sensor  200  is mounted, description of which will be omitted since the description is the same with the previous description. Anyhow, after the air outlet grill  300  is mounted, a more stable mounting state of the sensor  200  can be maintained, undoubtedly. 
   In the meantime, FIGS.  3 ˜ 12  illustrate examples in which the second fastening means includes the first screw hole  230  which passes through one end of the sensor  200  directly, the second screw hole  141  in correspondence to the first screw hole  230  is provided to the second mounting bracket  140  extended from the inside circumferential surface of the front bulkhead  100 , and, along with this, the second mounting bracket  140  is provided with the second screw hole  141  for mounting the sensor  200 , and the second pass through hole  160  for mounting the air outlet grill  300 . However, in the first, second, or third embodiment, the second fastening means is not limited to the examples illustrated in FIGS.  3 ˜ 12 . Other example of the second fastening means in the first, second, or third embodiment of the present invention will be described, with reference to FIG.  13 . 
   Though, in the example described with reference to  FIGS. 3  to  12 , the second mounting bracket  140  is provided with two holes, i.e., the second screw hole  141  and the second pass through hole  160 , in the example in  FIG. 13 , the second mounting bracket  140  is provided with one hole, i.e., a second pass through hole  160 , only. 
   In the embodiment illustrated in  FIG. 13 , the first screw hole  230  provided for fastening one end of the sensor  200 , the first pass through hole for fastening the air outlet grill  300 , and the second pass through hole  160  provided to the second mounting bracket  140  are designed to receive one fastening member, for an example, a screw, at the same time. To do this, the first screw hole  230  is provided such that the first screw hole  230  pass through a thin fourth plate  270  extended from the one end of the sensor  200 . 
   Once the first screw hole  230  is provided thus, after sensor  200  is disposed such that the first screw hole  230  and the second screw hole form one hole, and the first pass through hole in the air outlet grill  300  and the first screw hole  230  are aligned, the holes are fastened with one screw, to mount the sensor  200  and the air outlet grill  300  to the front bulkhead  100 , firmly. Of course, it is preferable that, before above fastening, the sensor  200  is fastened in advance by using the first or third fastening means provided to the sensor  200 . 
   Thus, the second fastening means may differ from the embodiments illustrated in FIGS.  3 ˜ 12 . Therefore, the examples shown in FIGS.  3 ˜ 12  are exemplary, but not limit the second fastening means. 
   In the meantime,  FIGS. 14 and 15  illustrate a fourth preferred embodiment of the sensor mounting structure of the present invention, which will be described in more detail. 
   Referring to  FIGS. 14 and 15 , the fastening means provided to the fourth embodiment includes a groove  217  in an upper surface of the sensor  200 . The groove  217  is provided as the fastening means in the fourth embodiment in a recess form along upper and side edges of the sensor  200  as shown in  FIG. 15 , for engagement with a part of the air outlet grill  300  as shown in FIG.  14 . For engagement with the groove  217  in the sensor  200 , the caved channel is provided with a long ridge  330 . 
   Once the groove  217  and the ridge  330  are provided to the sensor  200  and the air outlet grill  300  respectively, without using a separate fastening member, such as a screw, the sensor  200  can be mounted to the inside circumferential surface of the front bulkhead  100 . That is, as shown in  FIG. 14 , if the air outlet grill  300  is fastened after positioning the sensor  200  at the inside circumferential surface of the front bulkhead  100 , the ridge  330  of the air outlet grill  300  is engaged with the groove  217  in the sensor  200  such that the sensor  200  is locked by the caved channel  310  of the air outlet grill  300 , to limit movement of the sensor  200  and maintain a fastened state by a friction force. In the meantime, as shown in  FIG. 14 , if a top surface of the groove  217  and a bottom surface of the ridge  330 , which engage with each other, are sloped, a width direction movement of the sensor  200  can be prevented more effectively. 
   In the meantime, though not shown, in the fourth embodiment, more than one of the first, second, third fastening means described with reference to FIGS.  3 ˜ 13  may be provided for firmer fastening of the sensor  200 . 
   In the meantime, as shown in  FIG. 14 , the surface the electrodes  215  are provided thereto may have a sloped surface. Such embodiment is not limited to the fourth embodiment, but applicable to the first, second, and third embodiments. As shown in  FIG. 14 , the sloped surface has a lower part projected inward more than an upper part. Such a sloped surface of the sensor  200  permits more positive contact with the drying object, thereby improving a performance for sensing dryness of the drying object. 
   The present invention that can be realized in a variety of embodiments thus has a structure in which the sensor  200  is fabricated separate from the air outlet grill  300 , and the sensor  200  and the air outlet grill  300  are mounted to the front bulkhead  100  respectively. 
   Since the sensor  200  and the air outlet grill  300  of the present invention have very simple structures, molding thereof is very easy. Also, since mounting structures of the sensor  200  and the air outlet grill  300  to the front bulkhead  100  are very simple, assembly is simple. 
   The separate fabrication and mounting of the sensor  200  and the air outlet grill  300  on the front bulkhead  100  permits replacement of the sensor  200  only when the sensor  200  is out of order without replacement of other components, which is very economic. 
   Moreover, since the foregoing sensor mounting structure requires no special design change or re-design of peripheral components even in a case mounting of a different kind of sensor is required depending on models of the dryer in production of the dryer, only to require fabrication of the sensor in the same form, the present invention is very economical. 
   When the dryer of the present invention having the sensor  200  mounted thereon is put into operation to dry the drying object, the sensor  200  senses information, such as humidity in the drum  20 , and transmits to the controller of the dryer. The controller, having received the information from the sensor  200 , determines an extent of progress of the present drying from the information, and selects an operation method suitable to the extent of the progress, and controls various components. 
   When feed back is made thus, the controller re-determines a heating rate of the heater, a blowing rate and speed of the blower, rotation speed of the drum, a drying time period, and the like depending on the extent of dryness of the drying object in the drum  20 , and controls the dryer. 
   That is, if the extent of drying progress of the drying object is later than expectation after drying the drying object for a certain time period, the heating rate of the heater, the blowing rate of the blower, rotation speed of the drum, and the like are increased for fast drying. 
   Opposite to this, if the extent of drying progress of the drying object is faster than expectation after drying the drying object for a certain time period, the heating rate of the heater, the blowing rate of the blower, rotation and speed of the drum are decreased for slow down of the drying. 
   Upon completion of the drying, the sensor  200  senses it, and the controller stops operation, to prevent unnecessary excessive operation in advance. 
   Thus, the dryer of the present invention having the optimal feed back system always permits to progress an optimal drying, and reduce a drying time period and energy consumption by using the foregoing principle. 
   In the meantime, the device of the present invention having the sensor  200  which can sense information on an inside of the drum  20  provided thereto is applicable, not only to the dryer, but also to a drum type washing machine having a drying function. 
   The present invention has the following advantages. 
   First, the availability of easy realization of the feed back system at the dryer and drum type washing machine, permitting the controller to control components proper to an extent of drying progress of the drying object, can always provide an optimal dry service. 
   Second, the prevention of unnecessary excessive operation permits to shorten a drying time period, and reduce energy consumption. 
   Third, the very simple shapes of the sensor body and the air outlet grill permits easy formation of molds thereof, and the very simple assembly structure thereof with the front bulkhead provides a good assembly work. 
   Fourth, a component replacing cost can be saved, since what is required is replacement of the sensor only when the sensor is out of order. 
   Fifth, in designing a dryer or a drum type washing machine having another kind of sensor to be applied thereto, because what is required is fabrication of the sensor having the same shape, design change of the appliance is very simple and a new appliance can manufactured at a low cost. 
   It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. 
   For an example, the fastening means for the sensor is not limited to the embodiments described with reference to FIGS.  3 ˜ 15 , but may be available as many as one wishes by combinations of the different embodiments. That is, though not shown, an embodiment of the fastening means for the sensor including first fastening means having an extension member, and third fastening means having a third screw hole can be possible. 
   Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Technology Classification (CPC): 3