JP2011179740A - High-frequency cooking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent overheating of an LED in a high-frequency cooking device that uses the LED as a light source of an interior lighting unit. <P>SOLUTION: High-frequency waves generated by oscillation of a high-frequency generator 21 is supplied to a heating chamber 20 of the high-frequency cooking device 1. The inside of the heating chamber 20 is illuminated by the interior lighting unit 22. The light source of the interior lighting unit 22 is the LED 23. The LED 23 is cooled by air flow generated by a cooling fan 18. A control device 40 performs control to reduce the light emission intensity of the LED 23 when a door 11 of the heating chamber 20 is opened and the cooling fan 18 stops, or when the LED 23 reaches a predetermined temperature. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a high-frequency cooking apparatus.

  A high-frequency cooking apparatus that vibrates food molecules with high frequency (microwave) and thereby heats the food from the inside is generally known as “microwave oven” and has become a household necessity.

  In the heating chamber of the high-frequency cooking device, an interior lighting device is provided to make it easy to recognize the internal situation. An example of this can be seen in US Pat.

  The high-frequency cooking device described in Patent Document 1 includes light source control means for controlling light emitted from the illumination means to the heating chamber. The light source control means controls either the color or the intensity of the light that the illumination means irradiates the heating chamber. In addition, a human body detection element is provided to detect that a person is approaching and to change the intensity of light emitted from the illumination means by the light source control means. Further, a brightness sensor is provided in addition to the human body detection element, and the light intensity of the light sources of the illuminating means is changed by the light source control means according to the respective detection values to change the color of the light irradiated to the heating chamber. adjust.

  A proposal has been made to use a light emitting diode (hereinafter referred to as “LED” in the present application) as a light source of the interior lighting device. An example of this can be seen in US Pat.

JP 2006-17390 A JP-A-5-164331

  In the field of indoor lighting, from the viewpoint of energy saving, efforts to replace incandescent light bulbs with LED light bulbs have been actively promoted. Even in a high-frequency cooking device, it can be said that the LED is used as the light source of the interior lighting device. The LED used in the interior lighting device is cooled by an air flow generated by a fan provided for the purpose of cooling a heat generating component such as a magnetron, but there is one problem here.

  That is, the fan does not always keep rotating while the LED is on. When cooking is finished and the food is taken out by opening the door of the heating chamber, it is inconvenient for the user to turn off the illumination, so the LED is continuously lit. On the other hand, the fan is worried about the sound if it continues to operate after cooking is finished, and the user may misunderstand that the high frequency cooking device has failed, so it will stop if the door is opened It has become. As described above, when the LED is lit but the fan is stopped, the LED is overheated by self-heating.

  Further, even if the fan continues to rotate without the door being opened, the LED is overheated if the air flow stagnates due to the exhaust port being blocked. When the LED is overheated in this way, problems such as deterioration of the quality of the LED itself and shortening of the lifetime occur.

  This invention is made | formed in view of said point, and it aims at enabling it to avoid overheating of LED in the high frequency cooking apparatus which uses LED as a light source of an interior lighting device.

  In order to achieve the above object, the present invention provides a high-frequency cooking apparatus having an interior lighting device provided in a heating chamber, wherein the interior lighting device uses an LED as a light source, and the LED is disposed in the high-frequency cooking device. The LED is cooled by an air flow generated by the fan, and the LED normally emits light when the door of the heating chamber is opened and the fan stops or when the LED reaches a predetermined temperature. It is characterized in that the emission intensity is lower than the time.

  Further, the present invention is characterized in that, in the high-frequency cooking apparatus having the above-described configuration, a temperature detection device is disposed in the vicinity of the LED in order to detect the temperature of the LED.

  Moreover, the present invention is characterized in that, in the high-frequency cooking device having the above-described configuration, the control device reduces the light emission intensity of the LED by duty control.

  According to the present invention, when the LED is overheated or when the LED is turned on, the light emission intensity of the LED decreases, and therefore the LED does not overheat. Therefore, problems such as LED quality degradation and shortening of the lifetime are unlikely to occur, and a long-life interior lighting device with stable illumination quality can be obtained.

It is a perspective view showing one embodiment of the high frequency cooking device concerning the present invention. It is a vertical sectional view showing the outline of the internal structure of the high-frequency cooking device. It is a top view of a heating chamber bottom. It is a vertical sectional view of an operation part. It is a control circuit diagram of a high frequency cooking device.

  Hereinafter, the structure of the high frequency cooking device 1 according to the embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the upper and lower sides of the paper coincide with the upper and lower sides of the high-frequency cooking device 1. The left side of the paper is the left side of the high-frequency cooking device 1, and the right side of the paper is the right side of the high-frequency cooking device 1.

  The high frequency cooking device 1 includes a housing 10 made of a rectangular parallelepiped sheet metal structure. A heating chamber 20 made of a sheet metal structure having a rectangular parallelepiped shape is provided inside the housing 10. The heating chamber 20 has an opening on the front side of the housing 10. A metal door 11 that opens and closes the opening of the heating chamber 20 is provided on the front surface of the housing 10. The door 11 is connected to the housing 10 with a hinge 12 at the left end, and rotates in a horizontal plane with the hinge 12 as a fulcrum.

  The door 11 is formed with a window 13 through which the inside of the heating chamber 20 can be seen. The window 13 is fitted with a door screen 14 in which punching metal is sandwiched between two glass plates to prevent leakage of radio waves while maintaining transparency. In addition to the door screen 14, the door 11 is provided with measures for preventing radio wave leakage, and a gasket for preventing gas leakage from the heating chamber is attached and a lock device for keeping the closed state is provided. Detailed description is omitted.

  An operation unit 15 is formed on the right side of the door 11 in the housing 10. A group of operation keys 15b and a dial 15c are disposed on the operation unit cover 15a constituting a part of the housing 10 as an operation interface. A display device 15d is disposed above the operation key 15b.

  A total of 18 operation keys 15b are provided in three rows and six stages. Among them, as shown in FIG. 5, a numeric keypad and keys for “output switching”, “automatic menu”, “start”, “removal”, and “temperature” are included. In the bottom row, keys for “white”, “warm”, and “cold” that change the illumination color of the interior lighting device described later are arranged. Note that the types, number, and arrangement of the operation keys 15b are merely examples, and do not limit the invention.

  As shown in FIG. 4, the operation key 15b includes a key button 15e that transmits light, and an LED 15f that serves as a backlight is disposed behind each key button 15e. The LED 15f is mounted on the circuit board 15g, and a cylindrical reflector 15h is provided between the key button 15e and the corresponding LED 15f. The reflector 15h collects the light emitted by the LED 15f on the key button 15e and increases the brightness of the key button 15e.

  The display device 15d includes a display element 15i such as a display tube mounted on the circuit board 15g, and a display window 15j formed on the operation unit cover 15a. A lens made of transparent synthetic resin is fitted in the display window 15j.

  A rotary encoder 15k that is rotated by a dial 15c is mounted on the circuit board 15g. Further, a human body detecting element 151 for checking whether there is a person in front of the high frequency cooking device 1 and a light detecting element 15m (see FIG. 5) for checking the brightness around the high frequency cooking device 1 are mounted.

  As the human body detection element 151, for example, an infrared sensor that detects the presence of a human body or the approach of a human body by detecting infrared rays emitted from the human body is used. As the light detection element 15m, for example, a Cds cell whose resistance value changes according to the amount of received light is used.

  The human body detection element 15l and the light detection element 15m are arranged in a laterally aligned manner below the rotary encoder 15k. Light receiving windows 15n and 15o are formed in the operation unit cover 15a at positions corresponding to the front surfaces of the human body detection element 151 and the light detection element 15m, respectively. A reflector 15p similar to the reflector 15h is provided between the human body detecting element 15l and the light receiving window 15n and between the light detecting element 15m and the light receiving window 15o.

  The housing 10 is supported on a table or a table by legs 16 (see FIG. 2). The leg portion 16 has a total of four grounding portions 16a at the left and right positions on the front side and the back side, and forms a four-point support.

  Next, the internal structure of the high frequency cooking device 1 will be described. A high frequency generator (magnetron) 21 is attached to the outer surface of the right side wall of the heating chamber 20. The high frequency generator 21 supplies a high frequency to the inside of the heating chamber 20. The high frequency generator 21 is located in a space in the housing 10 that is the back side of the operation unit 15. In the same space, a circuit board (not shown) constituting a control device described later is also arranged.

  An interior lighting device 22 that illuminates the inside of the heating chamber 20 is disposed on the outer surface of the ceiling wall of the heating chamber 20. The interior lighting device 22 uses the LED 23 as a light source. There are a plurality of LEDs 23, and the illumination color as a whole can be switched to "white", "warm", and "cold". About LED23, it is good also as mixing each LED of red, green, and blue each, and it is good also as using what can light-emit in multiple colors by one.

  A large number of light transmission holes 24 through which light emitted from the LEDs 23 passes are formed in the ceiling wall of the heating chamber 20 so as to form a rectangular assembly. The size and arrangement of the light transmission holes 24 are the same as the punching metal holes of the door screen 14, and radio waves do not leak from there.

  A set of light transmission holes 24 is covered with a rectangular parallelepiped cover 25 from the outside of the heating chamber 20. The cover 25 surrounds the LED 23 and also serves as a mounting base for the LED 23. The cover 25 is made of punching metal so that air for cooling the LED 23 can enter and exit.

  An exhaust port 17 composed of a set of slits is formed in the ceiling wall of the housing 10, and a cooling fan 18 is disposed inside the exhaust port 17. When the cooling fan 18 is operated, the air inside the housing 10 is exhausted from the exhaust port 17, and as a result, the air outside the high-frequency cooking device 1 is sucked from an air inlet (not shown) provided at another location of the housing 10. It is. The sucked air flows toward the cooling fan 18, and the air flow cools heat-generating components such as the high-frequency generator 21, the LED 23, and the circuit board.

  A rotating shaft insertion hole 26 is formed in the bottom wall of the heating chamber 20 at a substantially central position. In addition, a circular shallow recess 27 is formed in the bottom wall of the heating chamber 20 with the rotary shaft insertion hole 26 as the center.

  In the heating chamber 20, a turntable 30 on which food to be heated is placed is disposed. The turntable 30 is a planar glass member whose upper surface is shallow and recessed like a dish. The turntable 30 is supported on the bottom wall of the heating chamber 20 by a roller stay 31. As shown in FIG. 3, the roller stay 31 is one in which one roller 31c is rotatably held at the tip of three arms 31b protruding radially from the central hub 31a at 120 ° intervals. The roller 31c contacts both the upper surface of the recess 27 and the lower surface of the turntable 30 to support the weight of the turntable 30 and food. An annular rib 30 a that surrounds the three rollers 31 c is formed on the lower surface of the turntable 30 so as not to be displaced with respect to the roller stay 31.

  The rotation is transmitted to the roller stay 31 through the rotation shaft 31d. The rotating shaft 31d is integrally formed with the hub 31a so as to hang from the hub 31a. The rotating shaft 31d passes through the rotating shaft insertion hole 26 vertically. The rotating shaft 31 d protruding from the bottom surface of the bottom wall of the heating chamber 20 is non-rotatably connected to the output shaft 32 a of the motor 32.

  The motor 32 is a shaft and is supported by the heating chamber 20 via a cup-shaped support base 33 fixed to the outer surface of the bottom wall of the heating chamber 20. The motor 32 incorporates a speed reduction mechanism and rotates the output shaft 32a at a reduced speed. A seal member 34 is disposed at a location where the output shaft 32 a passes through the support base 33 so that water does not leak from the support base 33 to the motor side. The upper end of the support base 33 is welded in close contact with the bottom wall of the heating chamber 20, and no gas or liquid leaks from here.

  The control system of the high frequency cooking device 1 has a configuration shown in FIG. The control device 40 is configured with a microcomputer as a core, receives output signals from various components, and outputs control signals to the various components.

  The components that output signals to the control device 40 include the following. First, there is a group of operation keys 15b. A door opening / closing detection switch 41 is provided for the door 11, and a signal is also output to the control device 40 from a door opening / closing detection circuit 42 including the door opening / closing detection switch 41. A temperature detection device 43 including a thermistor is disposed in the vicinity of the LED 23 of the interior lighting device 22, and a signal is also output from the temperature detection circuit 44 including the temperature detection device 43 to the control device 40.

  A signal is output from the human body detection element 151 to the control device 40 via the human body detection circuit 45. The human body detection circuit 45 includes an amplification circuit 45a, a reference value circuit 45b, a comparator 45c, and a signal generation circuit 45d. A signal is output from the light detection element 15 m to the control device 40 via the signal generation circuit 46. A signal is also output from the rotary encoder 15k to the control device 40.

  The components from which the control device 40 outputs control signals include the following. First, there is a display element 15i. The illumination unit 47 including the LED 15f corresponding to each key button 15e and the control circuit 48 of the cooling fan 18 are also control signal output targets. The control circuit 48 opens and closes the connection between the fan motor 18a and the commercial power source 19 by the relay switch 48a, and a control signal is output from the control device 40 to the switching circuit 48b of the relay switch 48a.

  The dimming circuit 49 of the interior lighting device 22 is also a control signal output target from the control device 40. The dimming circuit 49 includes a switching circuit 49 a of the LED 23, and the control device 40 controls the duty of the dimming circuit 49.

  Other components from which the control device 40 outputs control signals include a high-frequency drive power supply (not shown) attached to the high-frequency generator 21 and a driver circuit (not shown) for the motor 32.

  The operation of the high-frequency cooking device 1 is as follows. When heating is performed, food that is an object to be heated is placed on the turntable 30 and the door 11 is closed. When the door 11 is properly closed, the door open / close detection switch 41 becomes conductive, and a signal indicating that the door 11 is closed is output from the door open / close detection circuit 42 to the control device 40. In response to this, a command can be given through the operation key 15b. Further, the LED 15f is turned on to illuminate the key button 15e from behind.

  The user presses a necessary one of the group of operation keys 15b to select a cooking menu, a heating target temperature, or the like. The selection result is displayed on the display device 15d. Finally, when the “start” operation key 15b is pressed, cooking is started. The control device 40 outputs control signals to the high frequency generator 21, the cooling fan 18, the interior lighting device 22, and the motor 32, and operates them.

  By energizing the high frequency drive power supply, the high frequency generator 21 starts high frequency oscillation, and the food in the heating chamber 20 is heated at high frequency. The cooling fan 18 cools the heat generating components in the housing 10 by the air flow caused by the cooling fan 18. The motor 32 rotates the output shaft 32 a, and the output shaft 32 a rotates the roller stay 31. When the roller stay 31 rotates, the roller 31c rolls on the track surface 29 while supporting the turntable 30. The rolling roller 31c pushes the turntable 30 placed thereon further in the traveling direction. The angular velocity of the turntable 30 is about twice the angular velocity of the roller stay 31c.

  The control device 40 issues a static signal to the dimming circuit 49 and turns on the LED 23. Thereby, the inside lighting apparatus 22 illuminates the inside of the heating chamber 20 during heating. The illumination color is “white” by default, but “warm” and “cold” can be selected according to the cooking mode. For example, select “white” for oven cooking that requires judgment of grilled color, select “warm color” for cooking that does not require judgment of grilled color, cooking at low output such as thawing and fermentation, and vegetables If you want to show the green color of the image vividly, you can select “cold color”.

  The intensity of illumination can be adjusted by turning the rotary encoder 15k with the dial 15c. Note that an illumination intensity selection key may be provided in the operation key 15b, and the rotary encoder 15k may be used to adjust other parameters.

  The level of light emission intensity of the LED 15f that illuminates the key button 15e varies depending on the situation. In an environment where the surroundings are extremely bright, such as in the daytime, it is necessary to ensure sufficient light emission intensity of the LED 15f so that the user can easily see it. Conversely, in an environment where the surroundings are dark, such as at night, it may be felt dazzling if the light emission intensity of the LED 15f remains the same as in the daytime. First of all, if there is no one in front of the high frequency cooking device 1, it is not necessary to turn on the LED 15f. Lighting the LED 15f in vain or inappropriately is not only a waste of energy, but also shortens the life of the LED 15f.

  In this embodiment, useless lighting of the LED 15f as described above is prevented by using the human body detection element 15l and the light detection element 15m. The human body detection element 15l catches the presence of a human body by infrared rays emitted from the human body. The human body detection element 15l that has detected that there is a person in front of the high-frequency cooking device 1 outputs a signal to the human body detection circuit 45. The signal input to the human body detection circuit 45 is amplified by the amplifier circuit 45a, and the level is compared with the reference value signal output from the reference value circuit 45b by the comparator 45c. When the output signal level of the amplifier circuit 45a is higher than the level of the reference value signal, a human body detection signal is output from the signal generation circuit 45d to the control device 40.

  By the output of the human body detection signal, the determination condition that the LED 15f can be turned on is satisfied. In response to this, the control device 40 outputs a control signal for lighting the LED 15 f to the illumination unit 47. If the human body detection signal is not output, the determination condition that the LED 15f can be turned on is not satisfied, and the control device 40 does not output the control signal for turning on the LED 15f.

  When the light detection element 15m detects light, the light detection element 15m outputs a signal to the signal generation circuit 46, and the signal generation circuit 46 receives it and outputs a light detection signal to the control device 40. The control device 40 calculates the brightness level around the high-frequency cooking device 1 based on the level of the light detection signal. Based on the calculation result, the control device 40 gives a control signal for maintaining or increasing the emission intensity of the LED 15f to the illumination unit 47. Output.

  The control device 40 changes the light emission intensity of the LED 15f in a plurality of stages, such as “daytime level”, “nighttime level”, and “level when the room lighting is turned off at night”. The control is performed by outputting a control signal in which the duty ratio is adjusted. For example, in the “daytime level”, a control signal with a duty ratio of 10/10 is output in order to set the light emission intensity of the LED 15f to 100%. At the “night level”, a control signal with a duty ratio of 7/10 is output in order to set the light emission intensity of the LED 15f to 70%. At the “level when the room lighting is turned off at night”, a control signal with a duty ratio of 5/10 is output in order to set the light emission intensity of the LED 15f to 50%.

  Thus, by changing the light emission intensity of the LED 15f according to the ambient brightness and not lighting the LED 15f when there is no person in front of the high frequency cooking device 1, the power consumption is reduced and the life of the LED 15f is shortened. Can be extended.

  The control for the LED 15f is also applied to the display device 15d and the interior lighting device 22. That is, the display brightness of the display device 15d and the brightness of the illumination of the interior lighting device 22 are bright if the surroundings are bright, and darkened accordingly if the surroundings are dark, and the user does not feel dazzling. It is controlled to achieve appropriate brightness. Duty control can be applied to the brightness control as in the case of the LED 15f. If there is no person in front of the high frequency cooking device 1, the display device 15d stops displaying, and the interior lighting device 22 stops lighting.

  Thus, by finely adjusting the brightness of the display element 15i and the light emission intensity of the LED 23 according to whether or not there is a user and according to the ambient brightness, the power consumption can be reduced, and the display element 15i and the LED 23 can be reduced. Life can be extended.

  In response to the elapse of a predetermined time since the start of cooking, the operation by the user, or the detection of the sensor provided for that the food temperature has reached the predetermined value, or the user In response to the door opening / closing detection circuit 42 outputting a signal indicating that the door 11 is opened because the door 11 is about to open, the control device 40 receives the high frequency generator 21, the cooling fan 18, the interior lighting device 22, and The operation of the motor 32 is stopped. If cooking has been completed, the user opens the door 11 and takes out the food.

  When the door 11 is opened to take out the food, the interior lighting device 22 continues to be lit, and the user can take out the food from the bright heating chamber 20. On the other hand, the cooling fan 18 stops when the door 11 is opened because the user may misunderstand that the high-frequency cooking apparatus 1 has failed because the sound is annoying if the operation is continued. . Thus, if the interior lighting device 22 is turned on in a state where the cooling fan 18 is stopped, the LED 23 is overheated as it is.

  Therefore, in the present invention, it is assumed that the determination condition that the LED 23 is overheated or there is a risk that the cooling fan 18 is stopped when the LED 23 is lit is satisfied. In response to the determination condition being satisfied, the control device 40 performs control to reduce the emission intensity of the LED 23. That is, a pulse signal is output to the dimming circuit 49, the duty of the LED 23 is controlled, and the LED 23 is caused to emit light with, for example, a normal power consumption of 70%.

  As described above, when the door 11 of the heating chamber 20 is opened and the cooling fan 18 is stopped, the light emission intensity of the LED 23 is reduced, so that the LED 23 does not have so much heat, and even if the cooling fan 18 is in a stopped state, it is overheated. Is prevented. Thereby, deterioration of the quality of LED23 is suppressed and lifetime is also extended.

  Further, in the present invention, when the temperature detection device 43 reaches a predetermined temperature while cooking while the door 11 is closed and the cooling fan 18 is operating, the control device 40 indicates that the temperature of the LED 23 is in an overheated state or its temperature. It is determined that the temperature has reached a possible temperature. In response to this, the control device 40 reduces the emission intensity of the LED 23 in the same manner as described above.

  As described above, when the LED 23 reaches a predetermined temperature, the emission intensity of the LED 23 is reduced, so that the amount of heat generated by the LED 23 is reduced and overheating is prevented, so that the deterioration of the quality of the LED 23 is suppressed and the life is extended. .

  In the description so far, the high-frequency cooking apparatus that performs only high-frequency heating has been described, but it goes without saying that the present invention can also be applied to a high-frequency cooking apparatus that uses heating with steam.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be widely used for high-frequency cooking apparatuses.

DESCRIPTION OF SYMBOLS 1 High frequency cooking apparatus 10 Housing | casing 11 Door 15 Operation part 18 Cooling fan 20 Heating chamber 21 High frequency generator 22 Interior lighting apparatus 23 LED
30 Turntable 40 Control device 43 Temperature detection device

Claims (3)

In the high-frequency cooking device provided with an interior lighting device in the heating chamber,
The interior lighting device uses an LED as a light source,
The LED is cooled by an air flow generated by a fan arranged in the high-frequency cooking device,
The LED has a light emission intensity lower than that in normal light emission when the door of the heating chamber is opened and the fan stops or when the LED reaches a predetermined temperature.   The high frequency cooking apparatus according to claim 1, wherein a temperature detection device is disposed in the vicinity of the LED in order to detect the temperature of the LED.   The high-frequency cooking apparatus according to claim 1 or 2, wherein the control device reduces the light emission intensity of the LED by duty control.

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