Patent Publication Number: US-2023160569-A1

Title: Cooktop and knob assembly thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of U.S. application Ser. No. 17/460,642, filed on Aug. 30, 2021, which claims the benefit of the earlier filing date and the right of priority to Korean Patent Application No. 10-2020-0109648, filed on Aug. 28, 2020, the contents of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclose relates to a cooktop and a knob assembly of the cooktop, and more particularly, a knob assembly and a cooktop including the same that are capable of emitting light around a knob to enhance user recognition of operation of a product. 
     BACKGROUND 
     Cooktops that heat target objects use gas or electricity to heat the target objects. The cooktops can include a knob that rotates around a shaft to adjust an amount of heat applied to a target objector to manipulate the cooktop such as the setting of a cooking mode and the like. 
     A conventional cooktop includes knobs (or switches) around which light is emitted to improve visibility. 
       FIGS.  1  and  2    are diagrams illustrating a switch assembly in the conventional cooktop. 
     The switch assembly of the conventional cooktop can include a switch  1 , a light guide  2 , a switch holder  3 , a control panel  4 , a support bracket  5 , and a regulator  6 . 
     The light guide  2  includes a light guide path  2 - 1  and an LED module  2 - 2 . The LED module  2 - 2  is disposed at a first end of the light guide path  2 - 1 . Since the LED module  2 - 2  as a light source is disposed at the first end of the light guide path  2 - 1 , constant brightness of light cannot be ensured. For example, the first end of the light guide path  2 - 1 , at which the LED module  2 - 2  is disposed, is relatively bright, while a second end on the opposite side of the first end is relatively dark. 
       FIG.  3    is a diagram illustrating a portion of a knob assembly of another conventional cooktop. 
     The knob assembly in the another conventional cooktop includes a first light guide  7 , a second light guide  8 , and a bezel main body  9 . The second light guide  8  includes a leg  8 - 1  extended toward a light source, and a guide ring  8 - 2  forming a diffused light. In the another conventional cooktop, the light source is disposed in an end portion of the leg  8 - 1 . Accordingly, a portion of the guide ring  8 - 2 , which contacts the leg  8 - 1 , is relatively bright, while a portion far from the portion in contact with the leg  8 - 1  is relatively dark. 
     SUMMARY 
     The present disclosure is directed to a cooktop and a knob assembly that can enhance recognizing of operations of the cooktop. 
     Further, the present disclosure is directed to a cooktop and a knob assembly that can emit light uniformly around a knob. 
     Moreover, the present disclosure is directed to a cooktop and a knob assembly that can improve aesthetic qualities. 
     According to one aspect of the subject matter described in this application, a cooktop can include a heating part configured to heat a target object, and a manipulating part comprising (i) a control panel and (ii) a knob assembly that is coupled to the control panel and that is configured to control the heating part. The knob assembly can include a knob body that is disposed at a front surface of the control panel and that is configured to rotate with respect to a rotation shaft extended in a front-rear direction, a light diffusing part that is disposed at a rear side of the knob body and that is configured to diffuse light, and a light source part that is disposed at a rear side of the light diffusing part and that includes one or more light sources. The light diffusing part can include a light source corresponding part that is disposed at a position corresponding to one of the one or more light sources. A thickness of the light diffusing part along a first straight line that passes from a center of the light diffusing part through the light source corresponding part can be greater than a thickness of the light diffusing part along a straight line that does not pass through the light source corresponding part. 
     Implementations according to this aspect can include one or more of the following features. For example, the thickness of the light diffusing part along the first straight line can increase from the center of the light diffusing part toward an outer edge of the light diffusing part. 
     In some implementations, a thickness of the light diffusing part on a circumference of a first circle can decrease from an intersection point between the first circle and the first straight line toward an outer edge of the light diffusing part. In some implementations, the light diffusing part can include a plate having a thickness that increases from a center of the plate toward an outer edge of the plate along the first straight line, and a ring that surrounds the outer edge of the plate, that protrudes forward from the plate, and that has a diameter greater than a diameter of the knob body. 
     In some examples, a portion of the knob body can be inserted into a space defined by the plate and the ring. In some implementations, the cooktop can further include a knob ring that is disposed between the light diffusing part and the light source part, that is coupled to a front surface of the control panel, and that defines an exterior of the knob assembly. 
     In some implementations, the light diffusing part can include one or more first coupling hooks protruding rearward, and the knob ring can include one or more first connecting holes fitted-coupled to the one or more first coupling hooks. In some examples, the knob ring can include a plate having at least one of the one or more first connecting holes, and a ring that surrounds an outer edge of the plate, that protrudes forward from the plate, and that has a diameter greater than a diameter of the light diffusing part. 
     In some examples, the light diffusing part can be inserted into a space defined by the plate and the ring. In some implementations, the knob ring can include one or more second connecting hooks protruding rearward and to which the light source part is fitted-coupled. 
     In some implementations, a maximum thickness of the light diffusing part along the first straight line can be 1.5 times thicker than a minimum thickness of the light diffusing part. In some implementations, the light source part can include a plurality of light sources, and a thickness of the light diffusing part along a second straight line that passes from the center of the light diffusing part through an intermediate point between two adjacent light sources of the light diffusing part can be less than a thickness of the light diffusing part along a straight line that does not pass through the intermediate point. 
     In some examples, the thickness of the light diffusing part along the second straight line can remain constant from the center of the light diffusing part toward an outer edge of the light diffusing part. In some examples, an outermost thickness of the light diffusing part along the first straight line can be 1.5 times greater than a thickness of the light diffusing part along the second straight line. 
     In some implementations, the plurality of light sources can be spaced at regular intervals. 
     According to another aspect of the subject matter described in this application, a knob assembly can include a knob body configured to rotate with respect to a rotation shaft extended in a front-rear direction, a light diffusing part that is disposed at a rear side of the knob body and that is configured to diffuse light, and a light source part that is disposed at a rear side of the light diffusing part and that includes one or more light sources. The light diffusing part can include a light source corresponding part that is disposed at a position corresponding to one of the one or more light sources. A thickness of the light diffusing part along a first straight line that passes from a center of the light diffusing part through the light source corresponding part can be greater than a thickness of the light diffusing part along a straight line that does not pass through the light source corresponding part. 
     Implementations according to this aspect can include one or more following features. For example, the thickness of the light diffusing part along the first straight line can increase from the center of the light diffusing part toward an outer edge of the light diffusing part. 
     In some implementations, a thickness of the light diffusing part on a circumference of a first circle can decrease from an intersection between the first circle and the first straight line toward an outer edge of the light diffusing part. In some implementations, the light diffusing part can include a plate having a thickness that increases from a center of the plate toward an outer edge of the plate along the first straight line, and a ring that surrounds the outer edge of the plate, that protrudes forward from the plate, and that has a diameter greater than a diameter of the knob body. A portion of the knob body can be inserted into a space defined by the plate and the ring. 
     In some implementations, the knob assembly can further include a knob ring that is disposed between the light diffusing part and the light source part and that defines an exterior of the knob assembly. The light diffusing part and the knob ring can be fitted-coupled. 
     A cooktop and a knob assembly of the cooktop can include a light diffusing part capable of efficiently diffusing light, irradiated from a light source part, around a knob, thereby enhancing recognizing operations of the cooktop and ensuring improvement in user convenience. 
     Light irradiated to the light diffusing part can be diffused further toward a relatively thick portion of the light diffusing part. In the knob assembly and the cooktop provided with the same, since a thickness of the light diffusing part can increase toward an outer edge thereof, the light irradiated to the light diffusing part can be efficiently diffused to the outer edge of the light diffusing part. Thus, a brighter light can be emitted in an outer edge area of the light diffusing part, and uniform brightness can be ensured entirely in the outer edge area of the light diffusing part, thereby improving aesthetic qualities and enabling a user to recognize operations of the cooktop more conveniently. 
     Additionally, damage caused by a twist of the light source part can be limited, and the light source part can be readily assembled and replaced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1  and  2    are diagrams illustrating a switch assembly in a conventional cooktop. 
         FIG.  3    is a diagram illustrating a portion of a knob assembly in another conventional cooktop. 
         FIG.  4    is a diagram illustrating an exemplary cooktop provided with a knob assembly. 
         FIG.  5    is a diagram illustrating a perspective view of the knob assembly. 
         FIG.  6    is a diagram illustrating a cross-sectional view of the knob assembly in  FIG.  5   . 
         FIG.  7    is a diagram illustrating an exploded perspective view of the knob assembly in  FIG.  5   . 
         FIG.  8    is a diagram illustrating an exploded perspective view of an example of a knob body of the knob assembly. 
         FIG.  9    is a diagram illustrating a light diffusing part of the knob assembly viewed from a front. 
         FIG.  10    is a diagram illustrating the light diffusing part of the knob assembly viewed from a rear. 
         FIG.  11    is a diagram illustrating a cross-sectional view of a light diffusing part cut along line B-B′ in  FIG.  8   . 
         FIG.  12    is a diagram illustrating a cross-sectional view of a light diffusing part cut along line C-C′ in  FIG.  8   . 
         FIG.  13    is a diagram illustrating a view of a knob ring of the knob assembly viewed from the front. 
         FIG.  14    is a diagram illustrating a view of the knob ring of the knob assembly viewed from the rear. 
         FIG.  15    is a diagram illustrating a view of a knob ring coupled with a light source part in the knob assembly viewed from the rear. 
         FIG.  16    is a diagram illustrating an exploded perspective view of another exemplary knob assembly. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  4    is a diagram illustrating a view of an exemplary cooktop provided with a knob assembly. The cooktop can include a manipulating part  10  and a heating part, and the heating part can include a cooktop part  20 , an oven part  30 , and a drawer  40 . 
     Components for manipulating operations of the cooktop can be disposed at the manipulating part  10 . For example, a knob assembly  100  can be disposed at the manipulating part  10 , and the knob assembly  100  can rotate around a rotation shaft that extends in a front-rear direction to adjust a thermal power generated by each part (e.g., the cooktop part  20 , the oven part  30  and the drawer  40 ) of the cooktop or to set an operation mode of each part of the cooktop. The knob assembly  100  can be fixed to a control panel  11  of the manipulating part  10 . 
     The cooktop part  20  can be disposed at an upper portion of the cooktop. The cooktop part  20  can include at least one of cooktop burners  21 . The cooktop burner  21  can heat a vessel containing a target object or directly heat a target object to cook the target object using a flame that is produced by burning gases. 
     The oven part  30  can be disposed in a central portion of the cooktop. The oven part  30  can include a main body forming a cooking space in which a food item is cooked, and a burner assembly for cooking a target object accommodated in the cooking space. Additionally, the oven part  30  can include a door for opening and closing the cooking space. 
     The drawer  40  can slide into the cooktop or can be withdrawn from the cooktop and can keep a vessel containing a target object and the like at a predetermined temperature. 
     In  FIG.  4   , the cooktop includes the oven part, the cooktop part, and the drawer as a heating part for heating a target object, for example. However, the cooktop, in some implementations, may exclude some of the oven part, the cooktop part, and the drawer. 
       FIG.  4    shows a gas oven including the oven part, the cooktop part, and the drawer, which are capable of cooking a target object, as an example of the cooktop. But the subject matter of the present disclosure may be applied to various types of cooktops such as a cooktop that generates heat using electricity rather than gas or an oven and the like. For example, the cooktop part of the cooktop can include an induction heater capable of inductively heat a vessel and/or an electric heater capable of generating heat using electricity. 
     Hereinafter, the front denotes a front-surface direction of the cooktop, and the rear denotes a rear-surface direction of the coking appliance. 
       FIG.  5    is a diagram illustrating a perspective view of the knob assembly, FIG.  6  is a diagram illustrating a cross-sectional view of the knob assembly in  FIG.  5   , and  FIG.  7    is a diagram illustrating an exploded perspective view of the knob assembly in  FIG.  5   . 
     The knob assembly  100  can include a knob body  110 , a light diffusing part  120 , a knob ring  130 , a light source part  140 , and an adjusting part  150 , and the adjusting part  150  can include an ignition switch  151  and a valve  152 . 
     The knob body  110  can define an exterior of a front surface of the knob assembly  100 . The knob body  110  can be formed into a single component based on integration, or can be comprised of a plurality of components based on coupling. The knob body  110  can rotate around a rotation shaft ax that extends in the front-rear direction. For example, the knob body  110  can be rotatably coupled to the light diffusing part  120 , the knob ring  130 , the light source part  140 , and the adjusting part  150 . 
     The light diffusing part  120  can be disposed between the knob body  110  and the light source part  140 . The light diffusing part  120  can be entirely short and formed into a cylinder having a front surface that is completely open. The light diffusing part  120  can emit light around the knob body  110 . Additionally, the light diffusing part  120  can be fixed to an inside of the knob ring  130  and protect the light source part  140 . 
     The light diffusing part  120  may be made of a material capable of diffusing light, irradiated from the light source part  140 , therein. For example, the light diffusing part  120  may be made of an opaque plastic material. Accordingly, uniformity in brightness of light emitted around the knob body  110  can be improved. 
     Further, a position of the light diffusing part  120 , which corresponds to a position of the light source of the light source part  140 , can be thicker than another position of the light diffusing part  120 . Thus, the uniformity in the brightness of the light emitted around the knob body  110  can be improved, and the brightness of the light can increase. 
     The knob ring  130  can be disposed at a rear side of the light diffusing part  120 . For example, the knob ring  130  can be disposed between the light diffusing part  120  and the light source part  140 . The knob ring  130  can be short entirely and formed into a cylinder having a front surface that is completely open. Additionally, the knob ring  130  can fix the light source part  140 . Further, the knob ring  130  can be disposed at a front surface of the control panel  11  and form the exterior of the knob assembly  100 . 
     The knob ring  130  may be made of an opaque material. A surface of the knob ring  130  can be plated and/or coated and fix the light source part  140 . 
     The light diffusing part  120  and the knob ring  130  can be fixed to the control panel  11  in a state of being coupled to each other. 
     The light source part  140  can be disposed at the rear side of the light diffusing part  120 . The light source part  140  can include at least one of light sources  141  configured to irradiate light to a rear surface of the light diffusing part  120 . The light source  141  may be a light-emitting diode. When a plurality of light sources  141  is provided, the plurality of light sources  141  can be spaced at regular intervals. 
     The light source part  140  can be fixed to the knob ring  130  disposed at the rear of the light diffusing part  120 . For example, the light diffusing part  120  can be fixed to an inside of the front surface of the knob ring  130 , and the light source part  140  can be fixed to a rear surface of the knob ring  130 . 
     The adjusting part  150  can adjust thermal power output from the cooktop, or adjust operation of the cooktop such as a mode of the cooktop and the like, based on the rotation of the knob body  110 . When the cooktop uses gas as a heat source, the adjusting part  150  can include an ignition switch  151  or a valve  152 . 
     The ignition switch  151  can receive torque of the knob body  110 . An on/off state of the ignition switch  151  can change based on a rotation angle of the knob body  110 . The ignition switch  151  can be turned on and produce a spark on a fire mouth of a burner ( 21  in  FIG.  4   )/a spark on a burner ( 21  in  FIG.  4   ) when the knob body  110  makes a rotation at a predetermined angle. 
     The valve  152  can receive torque from the knob body  110 . An opening degree of the valve  152  can be determined based on a rotation degree of the knob body  110 . In some implementations, the valve  152  can receive torque from the knob body  110  only when the knob body  110  rotates in a state of being pressed. 
     The ignition switch  151  and the valve  152  can receive torque of the knob body  110  through a valve shaft. 
     The control panel  11  can be disposed at a rear side of the knob ring  130 . As described above, the light diffusing part  120  and the knob ring  130  can be fixed to the control panel  11  in the state of being coupled to each other. The control panel  11  can be a portion (e.g., a front surface of the cooktop part  10  in  FIG.  4   ) of the cooktop or a portion of the knob assembly  100 . The control panel  11  can have an opening  11 - 3  at which the light source part  140  is disposed. Additionally, the control panel  11  can have at least one of panel holes  11 - 1  and  11 - 2  through which the knob ring  130  is coupled to the control panel  11 . 
       FIG.  8    is a diagram illustrating an exploded perspective view of an exemplary knob body  110  of the knob assembly  100 . The knob body  110  can include a knob  111 , an insert  112 , screw bolts  113 - 1  and  113 - 2 , and a spring  114 . 
     The knob  111  can form the exterior of the front surface of the knob assembly  100 . The knob  111  can include a cylindrical body and a handle protruding forward from the body. 
     The insert  112  can be inserted into a rear surface of the knob  111 . The insert  112  can improve rigidity of the knob  111  and limit deformation of the knob  111 . The insert  112  may have a shape of doughnut. 
     The screw bolts  113 - 1  and  113 - 2  can fix the insert  112  and the knob  111 . 
     The spring  114  can be disposed inside the knob body  110 , and can connect between the knob  111  and the valve shaft. 
       FIG.  9    is a diagram illustrating a view of a light diffusing part  120  of the knob assembly  100  viewed from a front,  FIG.  10    is a diagram illustrating a view of the light diffusing part  120  of the knob assembly  100  viewed from a rear,  FIG.  11    is a diagram illustrating a cross-sectional view of a light diffusing part  120  cut along line B-B′ in  FIG.  9   , and  FIG.  12    is a diagram illustrating a cross-sectional view of a light diffusing part  120  cut along line C-C′ in  FIG.  9   . 
     The light diffusing part  120  can include a first plate  121  formed into a flat plate, and a first ring  122  surrounding an outer edge of the first plate  121  and protruding forward from the first plate  121 . For example, the light diffusing part  120  can have a cylindrical shape entirely as a result of coupling between the first plate  121  and the first ring  122 . The first ring  122  can have a diameter greater than a diameter of the knob body ( 110  in  FIG.  7   ). At least a portion of the knob body ( 110  in  FIGS.  7  and  8   ) can be inserted into a space formed by the first plate  121  and the first ring  122 . For example, the first ring  122  can be disposed in a way that an edge of a front surface of the first ring  122  is seen, when the knob assembly  100  is viewed from the front. Thus, a user may directly see light diffused through the light diffusing part  120 , resulting in improvement in visibility. 
     In  FIG.  9   , reference numerals  123 - 1 ,  123 - 2 , and  123 - 3  indicate light source corresponding parts of the light diffusing part  120 , corresponding to the positions of the light sources  141 , when the light source part ( 140  in  FIGS.  6  and  7   ) is fixed to the knob ring ( 130  in  FIGS.  6  and  7   ). For example, the light source corresponding parts  123 - 1 ,  123 - 2 , and  123 - 3  of the light diffusing part  120  can be points corresponding to forward directions of the light sources  141 . 
     An average thickness of the first plate  121  on straight lines (L 1 , L 2  and L 3  in  FIG.  9   ) passing from a center O of the first plate  121  through the light source corresponding parts  123 - 1 ,  123 - 2 , and  123 - 3  may be greater than a thickness of another portion of the first plate  121 . Additionally, on the straight lines (L 1 , L 2 , and L 3  in  FIG.  8   ), the thickness of the first plate  121  can increase from the center O toward an outer edge of the first plate  121 . The center O of the first plate  121  can be aligned with the rotation shaft (ax in  FIG.  7   ). 
     In the case of a first plate  121  made of a material capable of diffusing light, when light is irradiated to any one point of the first plate  121 , the light tends to be diffused to a direction in which a thickness of the first plate  121  increases rather than a direction in which the thickness of the first plate  121  decreases. In some implementations, the first plate  121  can have a thickness that increases from the center O of the first plate  121  toward the outer edge thereof. Specifically, the thickness of the first plate  121  can increase from the center O of the first plate  121  toward the outer edge thereof on the straight lines L 1 , L 2 , L 3 , and light can be irradiated to one point of the straight lines L 1 , L 2 , L 3 . Accordingly, the light irradiated to the first plate  121  can be smoothly diffused in a direction of the outer edge of the first plate  121 , and the light irradiated to the first plate  121  can be efficiently diffused toward an outer edge area of the first plate  121 . The light diffused to the outer edge area of the first plate  121  can be diffused to an edge of the front surface of the first ring  122  and as a result, can become brighter on the front surface of the first ring  122 . Further, the light diffused through the first plate  121  and the first ring  122  can be seen on the front surface of the knob assembly  100 . Thus, uniformity in brightness of the light can be ensured on the front surface of the first ring  122 . 
     On straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) passing from the center O of the first plate  121  through intermediate points between the light sources  141 , the first plate  121  can have a uniform thickness. 
     The first plate  121  can have a first plate hole  125 , thereon. In some implementations, the valve shaft can extend in the front-rear direction through the first plate hole  125 , and torque of the knob body ( 110  in  FIG.  7   ) can be delivered to the adjusting part ( 150  in  FIG.  7   ) through the valve shaft. 
     Referring to  FIG.  10   , a plurality of coupling hooks  124 - 1 ,  124 - 2 ,  124 - 3 , and  124 - 4  extended rearward from the first plate  121  can be disposed at a rear surface of the first plate  121 . The plurality of first coupling hooks  124 - 1 ,  124 - 2 ,  124 - 3 , and  124 - 4  can be fitted-coupled to the first coupling holes ( 134 - 1 ,  134 - 2 ,  134 - 3 , and  134 - 4  in  FIG.  13   ) formed at the knob ring ( 130  in  FIG.  7   ). Accordingly, the light diffusing part  120  and the knob ring  130  can be readily coupled to each other without an additional component. 
     The term “fitted-coupled” may refer that the light diffusing part  120  and the knob ring  130  are jointed by the first coupling hooks  124 - 1  to  124 - 4  being inserted into the first connecting holes  134 - 1  to  134 - 4  with a certain force so that the first coupling hooks  124 - 1  to  124 - 4  are caught in the first connecting holes  134 - 1  to  134 - 4 . 
     In  FIGS.  11  and  12   , LP indicates a position at which the light source  141  is disposed, and can be a position corresponding to the light source corresponding part  123 - 1  in  FIG.  9   . 
     Referring to  FIGS.  9  and  11   , the thickness of the light diffusing part  120 , on the straight line (i.e., L 1 , L 2  and L 3  in  FIG.  9   ) that passes from the center O of the light diffusing part  120  (specifically, the center O of the first plate  121 ) through the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3 , can be greater than the thickness of the light diffusing part  120  on the straight line that does not pass through the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3 . The increase in the thickness of the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3  of the light diffusing part  120  may result in the enhanced diffusion of light. 
     In some implementations, the thickness of the light diffusing part  120  on the straight line (i.e., L 4 , L 5  and L 6  in  FIG.  9   ) that connects a position (exactly, an intermediate point between adjacent light sources among a plurality of light sources), at which the light source  141  is not disposed, with the center O of the light diffusing part  120  (specifically, the center of the first plate  121 ) can be less than the thickness of the light diffusing part  120  on the straight line that does not pass through the intermediate point. Thus, light can be diffused in a desired direction. 
     In some implementations, on the straight line (L 1 , L 2 , and L 3  in  FIG.  9   ) connecting the light source corresponding part (a point of the light diffusing part  120 , corresponding to LP;  123 - 1  in  FIG.  9   ) with the center O of the light diffusing part  120  (specifically, the center of the first plate  121 ), the thickness of the light diffusing part  120  (specifically, the first plate  121 ) can increase from the center O of the first plate  121  toward the outer edge thereof. With the structure, light irradiated from the light source  141  can be diffused to the outer edge of the light diffusing part  120  (specifically, the first plate  121 ), and as a result, can be uniformly emitted through the end of the light diffusing part  120  (specifically, the first ring  122 ) outward. 
     In some implementations, on straight lines except for the straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the intermediate point between adjacent light sources, among the straight lines extending from the center of the light diffusing part  120  to the outer edge of the light diffusing part  120 , the thickness of the light diffusing part can increase from the center O toward the outer edge. In some implementations, an average thickness of the light diffusing part  120 , on the straight line (i.e., L 1 , L 2 , and L 3  in  FIG.  9   ) that passes from the center O of the light diffusing part  120  through the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3 , can be greater than an average thickness of the light diffusing part  120  on the straight line that does not pass through the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3 . 
     In some implementations, the thickness of the light diffusing part  120  (specifically, the first plate  121 ) can remain constant on the straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the intermediate point between light sources. In some implementations, the thickness of the light diffusing part  120  on the straight line (L 4 , L 5 , and L 6  in  FIG.  9   ) can be smallest among the thicknesses of the light diffusing part  120 . 
     Under the assumption that the thickness of the light diffusing part  120  (specifically, the first plate  121 ) is t, at a position (exactly, intermediate positions among a plurality of light sources) of the light diffusing part  120 , where the light source  141  is not disposed, a maximum thickness of the light diffusing part  120  (specifically, the first plate  121 ) can be about 1.4 t to 1.6 t, preferably, 1.5 t, on the straight line connecting the light source corresponding part (a point of the light diffusing part  120 , corresponding to LP;  123 - 1  in  FIG.  9   ) with the center O of the light diffusing part  120  (specifically, the center of the first plate  121 ). 
     Referring to  FIGS.  9 ,  11  and  12   , on a circumference of a virtual circle (e.g., L 7  in  FIG.  9   ) having any radius from the center O of the light diffusing part  120  (specifically, the center O of the first plate  121 ), the thickness of the light diffusing part can decrease as farther from an intersection point X 1 , X 2 , and X 3  between the straight lines (L 1 , L 2  and L 3  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the light source corresponding part  123 - 1 ,  123 - 2 ,  123 - 3  and the virtual circle (e.g., L 7  in  FIG.  9   ). Additionally, on the circumference of the virtual circle (e.g., L 7  in  FIG.  9   ) having any radius from the center O of the light diffusing part  120  (specifically, the center O of the first plate  121 ), the thickness of the light diffusing part can increase as farther from an intersection point X 4 , X 5 , and X 6  between the straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the intermediate points among adjacent light sources and the virtual circle (e.g., L 7  in  FIG.  9   ). 
     For example, on the circumference of the virtual circle (e.g., L 7  in  FIG.  9   ) having any radius from the center O of the light diffusing part  120 , the thickness of the light diffusing part  120  can decrease from the intersection point X 1 , X 2 , and X 3  between the straight lines (L 1 , L 2  and L 3  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3  and the virtual circle (e.g., L 7  in  FIG.  9   ) toward the intersection point X 4 , X 5 , and X 6  between the straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) connecting the center O of the light diffusing part  120  with the intermediate points among adjacent light sources and the virtual circle (e.g., L 7  in  FIG.  9   ). 
     For example, in the light diffusing part  120  of the knob assembly  100 , the thickness of the portion in which the light source is disposed, and the thickness on the straight lines (L 1 , L 2  and L 3  in  FIG.  9   ) passing through the center of the light diffusing part  120  can be greater than the thickness of the portion in which the light source is not disposed and the thickness on the straight lines (L 4 , L 5 , and L 6  in  FIG.  9   ) passing through the center O of the light diffusing part  120 . The portion having the greater thickness may have a sector shape, when viewed from the front. 
     Referring to  FIGS.  9  and  12   , on a straight line (e.g., L 8  in  FIG.  9   ) across the straight line (L 1 , L 2  and L 3  in  FIG.  9   ) passing through the center O of the light diffusing part  120  and the light source corresponding part  123 - 1 ,  123 - 2 , and  123 - 3 , the thickness of the light diffusing part  120  can decrease as farther from the straight line (L 1 , L 2  and L 3  in  FIG.  9   ). In some implementations, the straight line (L 8  in  FIG.  9   ) can be a straight line passing through the light source corresponding part ( 123 - 1  in  FIG.  9   ). Accordingly, light irradiated from the light source  141  can be uniformly diffused to the front surface of the first ring  122  of the light diffusing part  120 . 
       FIG.  13    is a diagram illustrating a view of a knob ring  130  of the knob assembly  100  viewed from the front,  FIG.  14    is a diagram illustrating a view of the knob ring  130  of the knob assembly  100  viewed from the rear, and  FIG.  15    is a diagram illustrating a view of a knob ring  130  coupled with a light source part  140  in the knob assembly  100  viewed from the rear. 
     Referring to  FIG.  13   , like the light diffusing part  120 , the knob ring  130  can be short entirely and formed into a cylinder. For example, the knob ring  130  can include a second plate  131 , and a second ring  132  surrounding an outer edge of the second plate  131  and protruding forward from the second plate  131 . The second ring  132  can form the exterior of the knob assembly. The second ring  132  can have a diameter greater than the diameter of the first ring  122  of the light diffusing part  120 . 
     The light diffusing part  120  can be inserted into and fixed to the knob ring  130 , i.e., a space formed by the second plate  131  and the second ring  132 . For example, first coupling holes  134 - 1 ,  134 - 2 ,  134 - 3 , and  134 - 4  can be formed on the second plate  131  of the knob ring  130 . The first coupling hooks  124 - 1 ,  124 - 2 ,  124 - 3 , and  124 - 4  formed at the light diffusing part  120  can be fitted-coupled respectively to the first coupling holes  134 - 1 ,  134 - 2 ,  134 - 3 , and  134 - 4 . 
     As illustrated in  FIG.  6   , a height of the first ring  122  can be less than a height of the second ring  132 . Accordingly, light emitted through the first ring  122  of the light diffusing part  120  can be limited from excessively escaping from a direction facing the front. 
     Additionally, the light source ( 141  in  FIG.  7   ) of the light source part ( 140  in  FIG.  7   ) can be disposed on the second plate  131 , and a plurality of light transmitting holes  133 - 1 ,  133 - 2 , and  133 - 3  through which light irradiated from the light source ( 141  in  FIG.  7   ) can be formed on the second plate  131 . 
     A through hole  135  can be formed in a central portion of the second plate  131 . The valve shaft of the valve  152  can pass through the through hole  135 . 
     Referring to  FIGS.  14  and  15   , a plurality of second coupling hooks  137 - 1 ,  137 - 2 ,  137 - 3 , and  137 - 4  for fixing the light source part ( 140  in  FIG.  7   ) can be disposed at the rear surface of the knob ring  130 . The light source part ( 140  in  FIG.  7   ) can be fixed to the plurality of second coupling hooks  137 - 1 ,  137 - 2 ,  137 - 3 , and  137 - 4  in a way that the light source part is fitted-coupled to the plurality of second coupling hooks. For example, the light source part ( 140  in  FIG.  7   ) can be disposed at the rear surface of the knob ring  130 , and then a proper pressure may be applied forward, such that the light source part ( 140  in  FIG.  7   ) is fitted-coupled and fixed to the second coupling hooks  137 - 1 ,  137 - 2 ,  137 - 3 , and  137 - 4 . 
     Since the light source part  140  is directly coupled to the knob ring  130  without being coupled to the control panel  11  or the adjusting part  150 , a twist of the light source part  140  can be limited even when the knob body  110  rotates, and the light source part  140  can be readily assembled and replaced. 
     Further, a plurality of coupling holes  136  can be formed on the second pate  131  of the knob ring  130 . The knob ring  130  can be coupled to the control panel ( 11  in  FIG.  7   ) through the coupling holes  136 . For example, the coupling holes  136  can be aligned with the panel holes  11 - 1  and  11 - 2  of the control panel ( 11  in  FIG.  7   ), and a bolt and the like can be fastened to the aligned coupling hole  136  and panel hole  11 - 1  and  11 - 2 , such that the knob ring  130  is fixed to the control panel ( 11  in  FIG.  7   ). 
       FIG.  16    is a diagram illustrating an exploded perspective view of another exemplary knob assembly  100 - 1 . The knob assembly  100 - 1  can include a knob body  110 - 1 , a light diffusing part  120 - 1 , a knob ring  130 - 1 , a light source part  140 - 1 , and an adjusting part  150 - 1 . The adjusting part  150 - 1  can be a rotary switch. In  FIG.  15   , reference numeral  11  indicates the control panel,  121 - 1  indicates the first plate,  122 - 1  indicates the first ring,  131 - 1  indicates the second plate, and  132 - 1  indicates the second ring. 
     The knob body  110 - 1 , the light diffusing part  120 - 1 , the knob ring  130 - 1 , and the light source part  140 - 1  can be respectively the same as the knob body  110 , the light diffusing part  120 , the knob ring  130 , and the light source part  140  that are described with reference to  FIGS.  7  to  14   . 
     For example, the knob assembly  100 - 1  in  FIG.  15    is the same as the knob assembly  100  described with reference to  FIG.  7    and the like except that the adjusting part  150 - 1  is a rotary switch. When the cooktop inductively heats a vessel or when the cooktop adopts an electric heater and the like using electricity to generate heat, a rotary switch may be applied instead of the adjusting part comprised of the ignition switch and the valve.