Cooking Heater

Abstract

 A cooking heater includes a heater (18, 19 and 20) having an adjustable output, a top plate (13) mounted over the heater (18, 19 and 20) and having a heating section (14, 15 and 16) on which a container containing food to be heated is placed, and a display (26, 32, 37, 62 and 63) provided on the top plate (13) for displaying an output state of the heater (18, 19 and 20). The display (26, 32, 37, 62 and 63) includes a display section (26, 32 and 37) disposed along an outer periphery of the heater (18, 19 and 20).

Description

[0001] This invention relates to a cooking heater comprising power adjustable heating means, a top plate provided over the heating means and having a heating section on which a container containing food to be heated is placed, and display means provided on the top plate for displaying a heating power of the heating means.

[0002] Japanese Patent Publication No. 11-8051 discloses one of the above-described cooking heaters of the built-in type which is built in a cooking cabinet. The disclosed cooking heater comprises a top plate 2 mounted on a top of the cooking cabinet 1 and heating means (not shown) provided below the top plate 2 as shown in FIG. 6. The heating means includes two induction heating coils and a radiant heater provided in the rear of the heating coils and including a nichrome wire coil. The top plate 2 includes two induction heating sections 3a and 3b corresponding to the induction heating coils respectively and a heater heating section 3c corresponding to the radiant heater. Regions of these heating sections 3a, 3b and 3c are defined by circular frames 3d, 3e and 3f printed on the top plate 2 respectively.

[0003] A roaster 9 is provided below the induction heating coil corresponding to the induction heating section 3a, inside the cooking cabinet 1. The roaster 9 comprises a sheathed heater (not shown). An operation panel 10 is provided on a right-hand front of the cooking cabinet 1. The operation panel 10 includes three operation knobs 10a for adjusting output powers of the induction heating coils, radiant heater and sheathed heater respectively and a power switch 10b.

[0004] Three output display sections 4, 5 and 6 are provided on a front portion of the top plate 2 for displaying output states of the heating means provided below the heating sections 3a, 3b and 3c respectively. A hot state display section 7 is further provided on the front portion of the top plate 2 to indicate that the top plate 2 is at a predetermined high temperature. Each of the output display sections 4 to 6 comprises a plurality of light emitting diodes (LEDs) 8 aligned in a row. Three rectangular frames 4a, 5a and 6a are printed on a surface of the top plate 2 so as to correspond to the LEDs 8 of the output display sections 4 to 6 respectively. The LEDs 8 are turned on so that the output state of each heating means is displayed according to the number of LEDs 8 turned on. In the hot state display section 7, the LEDs 8 are turned on to indicate that the top plate 2 is at a high temperature.

[0005] However, the foregoing conventional cooking heater has the following problem. In the heating of food by the induction heating coils, an eddy current is produced in the bottom of a saucepan or pot placed on each induction heating section 3a and 3b by a magnetic field generated when a high frequency current is supplied to each induction heating coil. The Joule's heat due to the eddy current heats the pot containing the food. Differing from the radiant heater, each induction heating coil does not generate heat. Accordingly, each induction heating section 3a or 3b does not change its state between an operating state in which the high-frequency current is being supplied into the induction heating coil and a non-operating state in which no high frequency current is supplied to the heating coil. Consequently, the user has a difficulty in understanding that the induction heating coils are active.

[0006] The display sections 4 and 5 are provided on the top plate 32 for displaying the output state of the induction heating coils respectively. The display sections 4 and 5 are slightly away from or are not close to the induction heating sections 3a and 3b respectively. Accordingly, when only one of the LEDs is turned on, the user tends to fail to notice that the induction heating coil is active.

[0007] Therefore, an object of the present invention is to provide a cooking heater in which the activated state of the heating means provided below the top plate can easily be noticed.

[0008] The present invention provides a cooking heater comprising heating means having an adjustable output and display means for displaying an output state of the heating means, characterized in that the display means includes a display section disposed along an outer periphery of the heating means. The cooking heater is preferably further characterized by a top plate provided over the heating means and having a heating section on which a container containing food to be heated is placed and characterized in that the display means is provided on the top plate.

[0009] Viewing the display section disposed along the outer periphery of the heating means, the user can reliably understand the location of the heating means in operation and the region of the heating section. The above-described construction is effective particularly in a case where the heating means comprises an induction heating coil in which to determine whether the heating means is in operation on the basis of the state of the heating section is difficult.

[0010] The display section is preferably disposed below the top plate and includes a plurality of light emitting elements visible from over the top plate through the top plate, and the display means preferably turns on some or all of the light emitting elements according to an output of the heating means. Consequently, the output power of the heating means can easily be understood on the basis of the number of light emitting diodes being actuated.

[0011] The cooking heater is preferably further characterized by a base for supporting the heating means; and characterized in that the light emitting elements are mounted on the base. Furthermore, the cooking heater is preferably further characterized by control means for controlling the heating means, and characterized in that the control means controls the heating means so that one half or more of the light emitting elements are turned on when heating is started. Consequently, since the region of the heating section is rendered clearer when heating is started, a container containing food can be prevented from being erroneously positioned.

[0012] The cooking heater is preferably further characterized by load detecting means for detecting as to whether food is placed on the heating section and characterized in that the display means causes at least some of the light emitting elements to flash when the load detecting means has detected no food placed on the heating section. Consequently, measures can quickly be taken even when food is wrongly placed on the heating section.

[0013] The invention will be described, merely by way of example, with reference to the accompanying drawings, in which:

FIG. 1 illustrates an appearance of a cooking heater of one embodiment in accordance with the present invention;

FIG. 2 is a plan view of a casing of the cooking heater with a top plate being eliminated;

FIG. 3 is a longitudinal section taken along line 3-3 in FIG. 1;

FIG. 4 is a longitudinal section taken along line 4-4 in FIG. 1;

FIG. 5 is a block diagram showing an electrical arrangement of the cooking heater; and

FIG. 6 is a view similar to FIG. 1, showing a conventional cooking heater.

[0014] One embodiment of the present invention will be described with reference to the drawings. The invention is applied to a cooking heater built in a system kitchen. Referring to FIG. 1, the cooking heater built in the system kitchen is shown. The cooking heater comprises a body 11 including an upper unit fitted into a cooking cabinet 12 from above and a lower unit fitted into the cooking cabinet 12 from the front. The upper unit comprises a generally thin rectangular box-shaped casing 17 (see FIG. 2) enclosing three heating means and a top plate 13 mounted so as to close an upper opening of the casing 17. The top plate 13 is made of a heat resisting glass. Two induction heating coils 18 and 19 serving as the heating means are disposed left and right in the casing 17, as shown in FIG. 2. A radiant heater 20 serving as the heating means is also disposed in the central rear interior of the casing 17. The radiant heater 20 comprises a nichrome wire coil.

[0015] Two induction heating sections 14 and 15 are provided on an upper surface of the top plate 13 so as to correspond to the induction heating coils 18 and 19 respectively, as shown in FIG. 1. A heater heating section 16 is further provided on the upper surface of the top plate 13 so as to correspond to the radiant heater 20. Pans or pots both serving as containers to be heated and containing food are to be placed on the heating sections 14 to 16 respectively although the pans or pots are not shown. Regions of the heating sections 14 to 16 are defined by circular frames 14a, 15a and 16a printed on the top plate 13 respectively. Two coil output display sections 26 and 28 are provided along parts of the frames 14a and 15a outside the induction heating sections 14 and 15 respectively. The coil output display sections 26 and 28 display output states of the induction heating coils 18 and 19 respectively. A heater output display section 37 is provided along a part of the frame 16a outside the heater heating section 16. The heater output display section 37 displays an output state of the radiant heater 20. A hot state display section 42 is provided on the central front of the top plate 13. The hot state display section 42 indicates that the top plate 13 is hot sufficiently for the cooking. The display sections 26, 28, 37 and 42 will be described in detail later.

[0016] The lower unit comprises a roaster 44 including a sheathed heater 58 (see FIG. 5) provided below a left-hand underside of the casing 17 in the cooking cabinet 12. The lower unit further comprises an operation panel 45 mounted on the front of the cooking cabinet 12 so as to be located on the right of a door 44a of the roaster 44. The operation panel 45 includes a power switch 46, an on-off switch 48a and an output adjusting switch 48b both for the left-hand induction heating coil 18, an on-off switch 50a and an output adjusting switch 50b both for right-hand induction heating coil 19, and an on-off switch 52a and an output adjusting switch 52b both for the central heater 20. The operation panel 45 further includes an on-off switch 54 for the sheathed heater 58 of the roaster 44, an operating section 59 including a timer switch 56, a power supply display section 47 turned on while the power switch 46 is on, output display sections 49, 51 and 53 displaying output states of the induction heating coils 18 and 19, and the heater 20 respectively, a roaster display section 55 displaying a working condition of the roaster 44, and a display section 60 (see FIG. 5) comprising a timer display section 57. Each display section comprises LEDs (not shown).

[0017] Referring to FIGS. 2 and 3, the induction heating coils 18 and 19 are mounted on disk-like bases 22 respectively. Ferrite 25 is fixed to the underside of each base 22 so as to correspond to the induction heating coil 18 or 19. Two temperature sensors 23 are mounted on central portions of the bases 22 with coil springs 24 being interposed therebetween respectively. The bases 22 are screwed inside the casing 17 so as to be located below the induction heating sections 14 and 15 so that the induction heating coils 18 and 19 are in proximity of the underside of the top plate 13, respectively. In this case, the coil springs 24 press the respective temperature sensors 23 against the underside of the top plate 13. The temperature sensors 23 detect temperatures of the induction heating sections 14 and 15 of the top plate 13, thereby indirectly detecting temperatures of pots placed on the induction heating sections, respectively.

[0018] Board mounting members 27 constituting the output display sections 26 and 32 are mounted by screws 27a on front halves of the outer peripheries of the bases 22, or portions of the outer peripheries of the bases 22 in front of lines A1 and A2 passing centers O1 and 02 of the induction heating coils 18 and 19 and extending horizontally as viewed in FIG. 2, respectively. Printed boards 29 are mounted on the respective mounting members 27. A plurality of light-emitting diodes (LEDs) 28 serving as light-emitting elements are mounted on each printed board 29. A light diffusing plate 30 is also mounted on each printed board 29 to diffuse light emitted from the LED 28.

[0019] Referring now to FIGS. 2 and 4, the central heater 20 is disposed on a bottom of a generally circular shallow dish-shaped base 33 fixed within the casing 17. A heat insulating material 34 is provided along an outer periphery of the base 33. A supporting member 35 is mounted on a front half of a peripheral bottom of the base 33 corresponding to a front half of the central heater 20 with respect to a line A3 passing the center 03 of the central heater and extending horizontally as viewed in FIG. 2. A coil spring 36 is interposed between the supporting member 35 and the bottom of the casing 17. The coil spring 36 urges the base 33 and the heat insulating material 34 so that upper ends of the base and material are pressed against the underside of the top plate 13. A board mounting member 38 constituting the output display section 37 is mounted on an upper portion of the supporting member 35 by a screw 38a. A printed board 40 is mounted on the board mounting member 38. A plurality of light emitting diodes (LEDs) 39 serving as light emitting elements are mounted on the printed board 40. A light diffusing plate 41 is also mounted on the printed board 40 for diffusing light emitted from the LEDs 39.

[0020] Further referring to FIG. 2, a printed board 43a constituting the hot state display section 42 is disposed at a central front interior of the casing 17. Three LEDs 43b are mounted on the printed board 43a. Light emitted by each of the LEDs 28, 39 and 43b constituting the output display sections 26, 32 and 37 and the hot state display section 42 is visible from over the top plate 13. Thus, portions of the top plate 13 corresponding to the display sections 26, 32, 37 and 42 each have a light transmission property.

[0021] Referring now to FIG. 5, an electrical arrangement of the cooking heater 11 is shown. A control circuit 62 mainly comprises a microcomputer (not shown). The operating section 59 delivers an operation signal to the control circuit 62. The temperature sensor 23 also delivers a signal to the control circuit 62. The control circuit 62 controls a drive circuit 63 to further control the display section 60, the coil output display sections 26 and 32, the heater output display section 37, and the hot state display section 42. The control circuit 62, drive circuit 63, and output display sections 26, 32 and 37 constitute display means in the embodiment. Furthermore, the control circuit 62 controls a drive circuit 64 to further control a cooling fan 21. The control circuit 62 further controls drive circuits 65 and 66 to control the radiant heater 20 and sheathed heater 58. The control circuit 62 further controls drive circuits 67 and 68 to supply on-off signals to switching elements (not shown) of inverter circuits 69 and 70, thereby controlling the induction heating coils 18 and 19. The control circuit 62 delivers timing signals to current detecting circuits 71 and 72 in synchronization with the on-off signals. Based on the timing signals, the current detecting circuits 71 and 72 detect input currents and regenerative currents of the inverter circuits 69 and 70 to supply the detected values to the control circuit 62. Based on the supplied detected values, the control circuit 62 determines whether normal pots such as steel pots or enameled pots are placed on the induction heating sections 14 and 15, respectively. More specifically, when the regenerative current values are excessively high relative to the input current values respectively, the control circuit 62 determines that normal pots are not placed on the induction heating sections 14 and 15, respectively. Thus, the control circuit 62 and the current detecting circuits 71 and 72 constitute load detecting means in the embodiment.

[0022] The operation of the cooking heater will be described. The control circuit 62 is provided with a control program carried out by the microcomputer. The control circuit 62 controls sections of the cooking heater on the basis of the control program, input signals from the operating section 59, signals from the temperature sensors 23, etc. Firstly, when the power switch 46 is turned on, the control circuit 62 turns on the power display section 47. For example, when a normal pot is placed on the left-hand induction heating section 14 and the switch 48a of the induction heating coil 18 is turned on, the control circuit 62 controls the left-hand induction heating coil 18 so that the heating output is rendered maximum. The control circuit 62 simultaneously turns on all the LEDs 28 of the output display section 26 and all the LEDs of the output display section 49. When the LEDs 28 of the output display section 26 are turned on, the top plate 13 transmits light emitted by the LEDs 28 such that the light is located along the front half of the outer periphery of the induction heating section 14. Accordingly, the user can easily understands that the induction heating section 14 is in operation. Furthermore, since the LEDs 28 render the region of the induction heating section 14 clearer, the user can confirm that the pot is normally placed on the induction heating section 14. Even when the pot is displaced from the induction heating section 14, the user can easily relocate the pot.

[0023] Upon operation of the output adjusting switch 48b, the control circuit 62 controls the drive circuit 67 to vary the output of the induction heating coil 18 and to change the number of the LEDs 28 turned on and the number of the LEDs 49 turned on. Thus, the user can confirm the output of the induction heating coil 18 on the basis of the number of the LEDs 28 turned on and the number of the LEDs 49 turned on.

[0024] A pot placed on the induction heating section 14 is sometimes not normal or the pot is sometimes displaced from the induction heating section 14 to a large extent. When the switch 48a is turned on under each of these conditions, the control circuit 62 determines that the pot placed on the induction heating section 14 is not normal, based on the detected input current value and regenerative current value supplied from the current detecting circuit 71. In this case, the control circuit 62 causes all the LEDs of the output display sections 26 and 49 to flash. Viewing the light flashing along the front half of the outer periphery of the induction heating section 14, the user can easily understand that the pot placed on the induction heating section 14 is not normal.

[0025] When the temperature of the top plate 13 detected by the temperature sensor 23 is at or above a predetermined value, the control circuit 62 turns on the LEDs 43b of the hot state display section 42 with the number of LEDs turned on depending on the detected temperature value. When the switch 48a is turned off, the control circuit 62 interrupts electric current supply to the induction heating coil 18, turning off all the LEDs of the output display sections 26 and 49. Furthermore, when the temperature detected by the temperature sensor 23 is below the predetermined value, the control circuit 62 turns off the LEDs 43b of the hot state display section 42. The right-hand induction heating coil 19 and the radiant heater 20 are operated in the same manner as described above and accordingly, the description is eliminated.

[0026] According to the foregoing embodiment, the output display sections 26, 32 and 37 display the output states of the induction heating coils 18 and 19 and radiant heater 20 respectively. The output display sections 26, 32 and 37 are disposed along the outer peripheries of the corresponding heating sections 14 to 16 so as to serve as display means for displaying the locations of the heating sections 14 to 16 respectively. Consequently, the user can easily understand the location and the heating output of the heating section in operation. Moreover, the output display sections 26, 32 and 37 are located along the front halves of the outer peripheries of the heating sections 14 to 16 respectively. Consequently, the output display sections 26, 32 and 37 can be prevented from being obstructed by the pots placed on the heating sections 14 to 16 respectively.

[0027] Each of the induction heating coils 18 and 19 and the radiant heater 20 starts at its maximum output. Accordingly, all the LEDs of each display section 26, 32 or 37 are turned on upon start of each of the induction heating coils 18 and 19 and the radiant heater 20. Consequently, the location of each heating section 14, 15 or 16 can further be rendered clearer. Furthermore, the LEDs 28 and 39 constituting the output display sections 26, 32 and 37 are mounted on the bases 22 and 33 of the heating means respectively. Consequently, the arrangement of each output display section 26, 32 or 37 can be simplified.

[0028] The starting output of each heating means may be set so that a half of or more LEDs are turned on. When determining that the pot placed on each heating section is not normal, the control circuit may cause a part of the LEDs of each output display section to flash. Each output display section may comprise a liquid crystal display panel with a backlight or display means by an optical fiber, instead of LEDs. Any heating means whose output is adjustable may be provided, for example, a halogen lamp heater.

[0029] The foregoing description and drawings are merely illustrative of the principles of the present invention and are not to be construed in a limiting sense. Various changes and modifications will become apparent to those of ordinary skill in the art. All such changes and modifications are seen to fall within the scope of the invention as defined by the appended claims.

Claims

1. A cooking heater comprising heating means (18, 19 and 20) having an adjustable output and display means (26, 32, 37, 62 and 63) for displaying an output state of the heating means (18, 19 and 20), characterized in that the display means (26, 32, 37, 62 and 63) includes a display section (26, 32 and 37) disposed along an outer periphery of the heating means (18, 19 and 20).

2. A cooking heater according to claim 1, further characterized by a top plate (13) provided over the heating means (18, 19 and 20) and having a heating section (14, 15 and 16) on which a container containing food to be heated is placed, and characterized in that the display means (26, 32, 37, 62 and 63) is provided on the top plate (13).

3. A cooking heater according to claim 2, characterized in that the display section (26, 32 and 37) is disposed below the top plate (13) and includes a plurality of light emitting elements (28 and 29) visible from over the top plate through the top plate, and the display means (26, 32, 37, 62 and 63) turns on some or all of the light emitting elements (28 and 29) according to an output of the heating means (18, 19 and 20).

4. A cooking heater according to claim 2 or 3, characterized in that the display section (26, 32 and 37) is disposed along the outer periphery of a first half of the heating section (14, 15 and 16).

5. A cooking heater according to claim 3, further characterized by a base (22 and 33) for supporting the heating means (18, 19 and 20), and characterized in that the light emitting elements (28 and 29) are mounted on the base (22 and 33).

6. A cooking heater according to claim 3, further characterized by control means (62) for controlling the heating means (18, 19 and 20), and characterized in that the control means (62) controls the heating means (18, 19 and 20) so that one half or more of the light emitting elements (28 and 29) are turned on when heating is started.

7. A cooking heater according to claim 3, further characterized by load detecting means (62, 71 and 72) for detecting as to whether food is placed on the heating section (14, 15 and 16), and characterized in that the display means (26, 32, 37, 62 and 63) causes at least some of the light emitting elements (28 and 29) to flash when the load detecting means (62, 71 and 72) has detected no container placed on the heating section (14, 15 and 16).

8. A cooking heater according to claim 2 or 3, characterized in that the heating means (18, 19 and 20) includes an induction heating coil (18 and 19).

9. A cooking heater according to claim 2 or 3, characterized in that the heating means (18, 19 and 20) includes a plurality of heating elements including an induction heating coil (18 and 19) and the top plate (13) includes a plurality of heating sections (14, 15 and 16) corresponding to the heating elements respectively.

Drawing