JP2008288085A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooker using a visible light display part (display LED) 27 for allowing a user to recognize the position of an infrared entering region 24 and to surely carry out temperature control of a heating object 20 by an infrared sensor 26, and capable of extending the service life of the visible light display part 27. <P>SOLUTION: This induction heating cooker includes: the infrared sensor 26 detecting an infrared ray emitted from the heating object 20 through the infrared entering region 24 formed on a top plate 2; a control part 29 controlling induction heating by a heating coil 21 based on the output of the infrared sensor 26; the visible light display part 27 arranged to allow a light emitting state to be viewed in the vicinity of the infrared entering region 24, and allowing a user to recognize the position of the infrared entering region 24 and to cover the infrared entering region 24 with the heating object 20; and a temperature sensor 30 arranged in the vicinity of the visible light display part 27. When the temperature of the temperature sensor 30 is set above a predetermined value, the control part 29 lowers or stop the output of the visible light display part 27. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an induction heating cooker that induction-heats an object to be heated such as a pan or a frying pan using an electromagnetic induction heating coil.

  In recent years, induction heating cookers that inductively heat an object to be heated such as a pan with a heating coil have been widely recognized because of their excellent features of safety, cleanliness, and high efficiency. In order to detect the temperature of an object to be heated, an induction heating cooker of this type has been proposed that includes an infrared sensor that detects infrared energy emitted from the object to be heated. The infrared sensor is provided below the top plate, and receives infrared rays emitted from an object to be heated that are incident on an infrared ray incident area formed so that infrared rays can pass through the top plate, and the temperature of the object to be heated. The signal which changes according to is output. The induction heating cooker described in Patent Document 1 detects the temperature of an object to be heated using an infrared sensor, and performs heating control of the heating coil based on the detected temperature.

Japanese Patent Laid-Open No. 3-184295

  In the induction heating cooker described in Patent Document 1, since the infrared incident area is provided in the center of the heating coil, there is little possibility that the object to be heated is placed at a position relatively shifted from the infrared incident area. . However, the central portion of the heating coil has a weaker magnetic field and a lower temperature of the object to be heated than the upper portion of the winding portion that is located away from the central portion of the heating coil. In controlling the temperature rise of the object to be heated, the method of detecting the temperature at the center of the heating coil does not provide sufficient response to the temperature rise of the object to be heated. To improve the temperature detection response of the object to be heated by detecting the temperature of the object to be heated above or near the heating coil winding part by forming the infrared incident area at a position off the center of the heating coil. However, since the infrared incident region is located at a position away from the center of the heating coil, there is a high possibility that the object to be heated is not placed on the infrared incident region. Therefore, the light emitted by the light emitting means such as the LED can be visually recognized in or near the infrared incident area, and the user is strongly aware of the existence of the infrared incident area, and the user is encouraged to cover it. it can.

  In such a configuration, it is easier for the user to view the light emitting means with the highest possible luminance, and it is possible for the user to visually recognize it more efficiently if it is provided near the top plate. A heating coil is provided near the lower portion of the top plate, and the light emitting means is heated by receiving heat from the object to be heated and heat from the heating coil. There is a problem that driving for a long time, for example, an LED, has a limit in maintaining a high luminance for a long time by increasing a driving current.

  The present invention solves the above-described problems. In order to make the user recognize the position of the infrared incident region or to cover the infrared incident region with a heated object, the visible light display unit such as an LED has a high output (high luminance). It is an object of the present invention to provide an induction heating cooker that can improve the visibility of the user and further extend the life of the visible light display unit.

  An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a heating coil that generates an alternating magnetic field and induction-heats the object to be heated, and an infrared incident area formed on the top plate. An infrared sensor that detects infrared rays emitted from the object to be heated, a control unit that controls heating by the heating coil based on the output of the infrared sensor, and a light emitting state provided through the top plate Includes a visible light display unit disposed so as to be visible in the vicinity of the infrared incident region, and a temperature detection unit that detects the temperature of the visible light display unit, and the control unit detects when the temperature detection unit detects a predetermined temperature or higher. Compared to the case where a temperature lower than the predetermined temperature is detected, the output of the visible light display unit can be reduced or stopped.

  The visible light display unit may be provided in the vicinity of the heating coil, and the temperature detection unit may detect the temperature of the heating coil instead of detecting the temperature of the visible light display unit.

  The temperature detection unit may be provided in the vicinity of the visible light display unit, and may detect the ambient temperature around the visible light display unit.

  The temperature detection unit is provided in the vicinity of the infrared sensor, and the control unit corrects the output of the infrared sensor based on the output of the temperature detection unit so as to reduce the influence of the temperature dependency of the infrared sensor output, and heats it. You may control the heating by a coil.

  The control unit may be capable of changing in a plurality of steps so that the magnitude of the output of the visible light display unit decreases as the temperature detected by the temperature detection unit increases.

  An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a heating coil that generates an alternating magnetic field and induction-heats the object to be heated, and an infrared incident area formed on the top plate. An infrared sensor that detects infrared rays emitted from the object to be heated, a control unit that controls heating by the heating coil based on the output of the infrared sensor, and a light emitting state provided through the top plate If the control unit recognizes that the object to be heated is heated by the heating coil, the object to be heated is heated by the heating coil. The output of the visible light display unit can be reduced or stopped as compared with the case where it is recognized that it is not heated.

  An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a heating coil that generates an alternating magnetic field and induction-heats the object to be heated, and an infrared incident area formed on the top plate. An infrared sensor that detects infrared rays emitted from the object to be heated, a control unit that controls heating by a heating coil based on the output of the infrared sensor, and a light emitting state that is provided below the top plate, A visible light display unit disposed so as to be visible in the vicinity of the infrared incident region, and the control unit, when the output of the infrared sensor is greater than or equal to a predetermined value, the output of the infrared sensor is less than the predetermined output value In comparison, the output of the visible light display unit can be increased.

  According to the induction heating cooker of the present invention, the visible light display unit is provided so that the user can recognize the position of the infrared incident region and prompt the user to properly cover the infrared incident region with the object to be heated. Further, the lifetime of the visible light display portion can be extended.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
[Configuration of induction heating cooker]
FIG. 1 is a perspective view of an induction heating cooker according to Embodiment 1 of the present invention. The induction heating cooker according to the present embodiment includes an outer case 1 and a top plate 2 provided on the upper portion of the outer case 1 and covered with a top frame 2a. A left induction heating burner 3 and a right induction heating burner 4 that are heated using heating coils are provided on the left and right of the top surface of the top plate 2, and a heating range corresponding to each heating coil is printed and displayed on the top surface of the top plate 2. Yes. A heated object such as a pot is induction-heated at a portion placed on the display unit indicating the heating range of the left induction heating burner 3 and the right induction heating burner 4.

  On the front side of the left induction heating burner 3 and the right induction heating burner 4, a left induction heating burner display unit 5 for displaying the heating output of the left induction heating burner 3 and the right induction heating burner 4 and a right induction heating burner display unit. 6 is provided. Further on the front side are a left induction heating burner operation switch (operation unit) 7 and a right induction heating burner operation switch (operation unit) 8 for the user to control the heating of the left induction heating burner 3 and the right induction heating burner 4 respectively. Are provided in a line in the left-right direction. On the front surface of the outer case 1, a power switch 9 is provided on the right.

  FIG. 2 is a configuration diagram of the induction heating cooker according to the first embodiment of the present invention. Although there are two induction heating burners in FIG. 1, only one opening is shown in FIG. 2 for convenience of explanation. Below the top plate 2, a heating coil is provided at a position corresponding to the circular display indicating the heating range of the induction heating burners 3, 4 to generate an AC magnetic field and induction-heat the object 20 to be heated. . In the present embodiment, the heating coil has a split winding configuration with an inner coil 21a and an outer coil 21b. Hereinafter, the inner coil 21a and the outer coil 21b are collectively referred to as a heating coil 21. The heating coil 21 does not need to have a split winding configuration. The heating coil 21 is placed on a heating coil support 22 provided below the top plate 2. The lower surface of the heating coil support 22 is provided with a ferrite 23 that is a magnetic body that concentrates the magnetic flux toward the back side of the heating coil 21 in the vicinity of the heating coil 21.

  In the top plate 2, a portion 24 that faces the space portion between the inner coil 21 a and the outer coil 21 b is an infrared incident region, and is formed so that infrared rays can be transmitted. The top plate 2 is entirely formed of a heat-resistant ceramic that can transmit infrared rays, and the lower surface other than the infrared incident region 24 is covered with a printed film that hardly transmits infrared rays. The configuration of the infrared incident region 24 is not limited to this. A portion of the top plate 2 other than the infrared incident region 24 may be made of a material that does not transmit infrared rays, and a portion of the infrared incident region 24 may be made of a material that can transmit infrared rays. Moreover, you may comprise the circumference | surroundings of the infrared incident area | region 24 with the printed film whose infrared transmittance is not zero. A cylindrical light guide tube 25 having upper and lower openings perpendicular to the upper and lower surfaces of the heating coil 21 between the inner coil 21 a and the outer coil 21 b below the infrared incident region 24 is formed integrally with the heating coil support 22. And provided. The infrared sensor 26 is provided to face the lower opening of the light guide tube 25. Infrared rays radiated from the bottom surface of the object to be heated 20 increase in radiant energy as the temperature of the object to be heated 20 increases. This infrared light is incident from an infrared incident region 24 provided on the top plate 2, passes through the light guide tube 25, and is received by the infrared sensor 26. The infrared sensor 26 outputs a detection signal based on the amount of infrared energy received.

  In addition, when the heating coil 21 is not a division | segmentation winding structure, the infrared rays incident area | region 24 can be provided in opening of the center part of the heating coil 21. FIG. In this case, when the infrared incident region 24 is as close as possible to the winding of the heating coil 21, the temperature of a higher temperature portion of the object to be heated 20 can be detected by the infrared sensor 26.

  The display LED 27 is provided in the vicinity of the infrared sensor 26 and is attached to the heating coil holding base 22 together with the infrared sensor 26. That is, the display LED 27 is provided in the vicinity of the heating coil 21 and the infrared sensor 26 below the top plate 2. The display LED 27 is arranged so that the user can visually recognize the light emission state near the infrared incident region 24 through the top plate 2 from above the device. For example, the light emitted from the display LED 27 provided below the heating coil 21 is guided to the vicinity of the back surface of the top plate 2 by the light guide 27b to emit light. Therefore, the display LED 27 has a function of allowing the user to recognize the position where the infrared incident region 24 exists. As shown in FIG. 1 when viewed from the top of the device, the light emitting region 27a where the light of the display LED 27 can be visually recognized is formed in the vicinity of the infrared incident region 24. It is provided on the near side from the center of the heating coil 21. By setting the positional relationship between the infrared incident region 24 and the light emitting region 27a in this manner, it is possible to increase the probability of covering the infrared incident region 24 by covering the light emitting region 27a with the bottom surface of the article 20 to be heated. In order to further increase the probability that the infrared incident region 24 is covered with the bottom surface of the object to be heated 20, the infrared incident region 24 and the light emitting region 27 a are on or near a straight line that passes through the approximate center of the heating coil 21 and is perpendicular to the front surface of the main body. It is desirable that the light emitting region 27a is provided in front of the infrared incident region 24.

  An inverter circuit 28 that supplies a high-frequency current to the heating coil 21 and a control unit 29 that controls the operation of the inverter circuit 28 are provided below or around the heating coil 21. The operation unit 7 is provided on the front surface or the upper surface of the device, and includes a heating off / on key 7a for starting or stopping a heating operation, a down key 7b for reducing output, and an up key 7c for increasing output. . The control unit 29 controls the start / stop of the supply of the high-frequency current to the heating coil 21 and the magnitude of the high-frequency current supplied to the heating coil 21 based on the output signal of the operation unit 7 and the output signal of the infrared sensor 26. In addition, the entire other induction heating cooker is controlled.

  Furthermore, the induction heating cooker of this Embodiment has the temperature sensor 30 which is provided in the vicinity of the display LED 27 and detects the ambient temperature around the display LED 27. The temperature sensor 30 is a temperature detection unit, and includes a temperature detection element such as a thermistor. The control unit 29 determines whether or not the temperature detected by the temperature sensor 30 is equal to or higher than a predetermined temperature. When the control unit 29 determines that the temperature is equal to or higher than the predetermined temperature, the control unit 29 suppresses a decrease in the life of the display LED 27 and is less than the predetermined temperature. The output of the display LED 27 can be reduced or its driving can be stopped as compared with the case of.

[Operation of induction heating cooker]
Hereinafter, the basic operation of the induction heating cooker will be described. When the power switch 9 is turned on by the user, the control unit 29 enters a standby mode. When a heating start command is input from the heating off / on key 7a of the operation unit 7 in the standby mode, the control unit 29 enters the heating mode. In the heating mode, when the heating off / on key 7a is operated (for example, pressed) and a heating stop command is input, the control unit 29 enters a standby mode and stops heating. In the heating mode, when a heating power increase / decrease command is input by operating (for example, pressing) the heating output increase / decrease keys 7b and 7c, the control unit 29 controls the switching elements of the inverter circuit 28 based on the input command. Then, the amount of high-frequency current supplied to the heating coil 21 is controlled. When a high frequency current is supplied to the heating coil 21, a high frequency magnetic field is generated from the heating coil 21, and the object to be heated 20 placed on the top plate 2 is induction heated.

  After the power switch 9 is turned on and before the heating off / on key 7a of the operation unit 7 is operated, that is, in a standby state, the control unit 29 recognizes the display LED 27 and the position of the infrared incident region 24 to the user. In addition, a drive signal is output to urge the infrared incident region 24 to be properly covered with the object to be heated 20 to emit light. In addition, the user is instructed by an instruction manual or the like so as to cover the object to be heated 20 before starting the heating, or a precaution to that effect is displayed on the top plate 2, or It is instructed by notification or display by voice or text. The user places the object 20 to be heated above the display LED 27 to cover the display LED 27, and then operates the heating off / on switch 7a to start heating.

  The infrared sensor 26 is formed of a silicon photodiode and has output characteristics shown in FIG. In FIG. 3, the horizontal axis represents the temperature of the bottom surface portion of the object to be heated 20 facing the infrared incident region 24, and the vertical axis represents the output voltage of the infrared sensor 26. In the present embodiment, as shown in FIG. 3, the infrared sensor 26 is configured to exhibit a characteristic in which an output starts to be generated when the temperature of the object to be heated 20 reaches T0 (about 250 ° C.) and rises rapidly. Yes. The control unit 29 receives the output voltage of the infrared sensor 26 and detects a difference ΔX between the output voltage at the start of heating and the current output voltage. For example, in FIG. 3, if the temperature of the object to be heated 20 is T1 (for example, 30 ° C.) at the start of heating, the difference from the output voltage value becomes ΔX when the object to be heated 20 reaches a temperature T3 (for example, 290 ° C.). . If the temperature of the object to be heated 20 is T2 (for example, about 260 ° C.) at the start of heating, the output voltage value at the start of heating and the current output voltage when the object to be heated 20 reaches a temperature T4 (for example, 298 ° C.). And ΔX is ΔX. When the control unit 29 receives the output voltage of the infrared sensor 26 and detects a difference ΔX between the output voltage at the start of heating and the current output voltage, the control unit 29 stops the operation of the inverter circuit 28 or reduces the heating output. The temperature rise of the article to be heated 20 is suppressed. By controlling the temperature rise of the article to be heated 20 in this way, the difference in temperature at the start of heating or the influence of ambient light such as visible light that is steadily input is reduced, and the temperature is below about 300 ° C. The bottom surface temperature of the object to be heated 20 can be suppressed, and the temperature rise of the object to be heated 20 can be controlled to be accurately suppressed.

  When the room is dark and the heating object 20 covering the infrared incident area 24 is moved and removed so as not to cover the infrared incident area 24 after heating is started, the difference ΔX is detected. However, since the display LED 27 exists in the vicinity of the infrared incident area 24 and the display LED 27 is easily visible when the room is dark, the visibility of the light of the display LED 27 is increased, and the user is heated from the infrared incident area 24. It can be easily recognized that the object 20 is detached, and the user can be prompted to cover the position of the object 20 to be heated, that is, the display LED 27 with the object 20 to be covered.

  When the room is bright, after heating is started, the heated object 20 covering the infrared incident area 24 is moved and removed so as not to cover the infrared incident area 24, as in the case where the room is dark, The user recognizes that the object to be heated 20 is not in an appropriate position by visually recognizing the display LED 27, but the display LED 27 becomes difficult to see because the room is bright. However, in this case, disturbance light enters from the infrared incident region 24 and the output voltage of the infrared sensor 26 increases, so that the difference ΔX is detected and the control unit 29 detects the heating output even when the object to be heated 20 is not at a high temperature. Therefore, the temperature of the object to be heated 20 can be prevented from excessively rising due to the infrared sensor 26 not properly detecting the temperature of the object to be heated 20.

[Light emission control of display LED of induction cooking device]
The induction heating cooker according to the present embodiment includes a display LED 27 in the vicinity of the heating coil 21 that is a heat generating component, detects the temperature in the vicinity of the display LED 27, and controls the output of the display LED 27 based on the detected temperature. Specifically, when the detected temperature is low, the output of the display LED 27 is increased, and as the detected temperature increases and exceeds a preset reference temperature, the drive output value to the display LED 27 is gradually reduced. And stop when the detected temperature exceeds a preset predetermined temperature. FIG. 4 is a flowchart showing light emission control processing of the display LED 27 by the induction heating cooker according to the first embodiment of the present invention. Below, the light emission control of display LED27 with respect to one induction heating burner is demonstrated for convenience of explanation.

  In FIG. 4, the control unit 29 inputs the temperature of the temperature sensor 30 and the output value of the infrared sensor 26 (S1). First, the control unit 29 determines whether or not the output value of the infrared sensor 26 is equal to or higher than a predetermined value W (in this embodiment, the temperature of the article to be heated 20 is an output value corresponding to about 260 ° C.). Judgment is made (S2). If the output value of the infrared sensor 26 is equal to or greater than the predetermined value W (Yes in S2), it is estimated that the indoor sensor is bright and the infrared sensor 26 may receive disturbance light such as visible light, and the temperature When the temperature of the sensor 30 is high, the following steps for gradually reducing the drive current of the display LED 27 are not performed, and the output of the display LED 27 is increased regardless of the temperature of the temperature sensor 30 with priority given to the visibility (S3). ).

  When the output value of the infrared sensor 26 is less than the predetermined value W (No in S2), the drive current of the display LED 27 is gradually reduced as the temperature of the temperature sensor 30 increases. The controller 29 determines whether or not the temperature of the temperature sensor 30 is 80 ° C. or higher (S4). When the temperature of the temperature sensor 30 is less than 80 ° C., it is estimated that the degree of life reduction of the display LED 27 is small, so the output of the display LED 27 is increased (S3). When the temperature of the temperature sensor 30 is 80 ° C. or higher (Yes in S4), it is further determined whether or not the temperature of the temperature sensor 30 is 100 ° C. or higher (S5). When the temperature of the temperature sensor 30 is 80 ° C. or higher and lower than 100 ° C., the output of the display LED 27 is set to the middle (S6). When the temperature of the temperature sensor 30 is 100 ° C. or higher, it is further determined whether or not the temperature of the temperature sensor 30 is 105 ° C. or higher (S7). When the temperature of the temperature sensor 30 is 100 ° C. or higher and lower than 105 ° C., the output of the display LED 27 is made small (S8). When the temperature of the display LED 27 is 105 ° C. or higher, the output of the display LED 27 is stopped (S9). After the processes of S3, S6, S8, and S9, the process returns to step 1 (S1) and the above process is repeated while monitoring the output values of the temperature sensor 30 and the infrared sensor 26.

  As described above, in the induction cooking device of the present embodiment, the control unit 29 sets three different reference temperatures (80 ° C., 100 ° C., and 105 ° C.), and is detected by the temperature sensor 30 that is a temperature detection unit. When the temperature to be detected is equal to or higher than each of the reference temperatures, the output of the display LED 27, which is a visible light display unit, can be reduced or stopped as compared with the case where the temperature is less than the reference temperature. The control unit 29 selects and switches between a state of driving with three-stage output and a state of stopping output so that the output LED 27 has a smaller output as the temperature of the display LED 27 is higher. When the temperature of the display LED 27 is low by controlling the output of the display LED 27 based on the temperature detected by the temperature sensor 30 provided in the vicinity of the display LED 27, the control unit 29 is used because the degree of life reduction is suppressed. In order to improve the visibility of the user, the output of the display LED 27 is increased (the current is increased to increase the brightness), and when the temperature of the display LED 27 is high, priority is given to the suppression of the life reduction of the display LED 27. The output of the LED 27 is reduced to a medium or small value (the current is decreased to a medium or small value to decrease the luminance to a medium or small value) or stopped (turned off). Accordingly, the display LED 27 can be used to increase the brightness of the display LED 27 and improve the visibility so that the user can strongly recognize the position of the infrared incident area and to cover the infrared incident area 24. When it is estimated that the degree of life reduction is large, the luminance can be lowered to extend the life of the display LED 27 and the reliability of the display LED 27 can be improved.

  Further, since the control unit 29 prohibits the output of the display LED 27 from being lowered when the output of the infrared sensor 26 is equal to or greater than the predetermined value W, the visibility of the display LED is prevented from being lowered when the room is bright. be able to.

  In the present embodiment, the control unit 29 changes in three stages so that the higher the temperature detected by the temperature sensor 30 that is the temperature detection unit, the smaller the output of the display LED 27 that is the visible light display unit. Although the temperature rise of the display LED 27 is suppressed, the output of the display LED 27 may be changed in two or more stages other than the three stages. The presence / absence of the output of the LED 27 (turned on or off) may be switched.

  In the present embodiment, the control unit 29 detects the temperature of the display LED 27 based on the output of the temperature sensor 30 provided in the vicinity of the heating coil 21 and the display LED 27, and outputs the display LED 27 based on the detected temperature. However, the present invention is not limited to this. You may make it the temperature sensor 30 measure the temperature of the location which is correlated (proportional relationship) with the temperature of the display LED 27. For example, when the display LED 27 is provided in the vicinity of the heating coil 21 and the temperature rises due to the heat generated by the heating coil 21, the temperature sensor 30 is provided at a position where the temperature change of the heating coil 21 is detected. It can be estimated whether the display LED 27 is in a high-temperature atmosphere. For example, a temperature sensor 30 (not shown) such as a thermistor provided near the heating coil 21 but not near the display LED 27 may be provided. In addition, when the display LED 27 rises in temperature due to the heat generated by the article to be heated 20, a temperature sensor 30 such as a thermistor may be provided so as to detect the back surface temperature of the top plate 2 by heat conduction. Since the temperature sensor that detects the temperature of the heating coil 21 or the object to be heated 20 is often used to control the temperature of the heating coil 21 or the object to be heated 20, the temperature sensor 30 that estimates the temperature of the display LED 27 and It is good to use also.

When the temperature sensor 30 is provided in the vicinity of the infrared sensor 26 as in this embodiment, the control unit 29 further outputs the output of the infrared sensor 26 based on the output of the temperature sensor 30. May be corrected so as to reduce the influence of the temperature dependency on the output of the sensor, and the magnitude of the high-frequency current supplied to the heating coil 21 may be controlled based on the corrected output of the infrared sensor 26. Thereby, since the temperature of the to-be-heated material 20 can be detected more correctly, the temperature of the to-be-heated material 20 can be controlled more accurately.
In the present embodiment, the LED (display LED 27) is used as the visible light display unit, but the present invention is not limited to this, and other light emitting elements may be used.

Embodiment 2
FIG. 5 is a circuit configuration diagram of the induction heating cooker according to the second embodiment of the present invention. In FIG. 5 and the following description, components having the same numbers as those shown in the first embodiment shown in FIG. 2 have the same functions. In the induction heating cooker according to the first embodiment, the control unit 29 controls the output of the display LED 27 based on the output value of the temperature sensor 30 and the output value of the infrared sensor 26. In contrast, in the induction heating cooker according to the second embodiment, the control unit 31 outputs the output of the display LED 27 based on whether or not the object to be heated 20 is heated and the output value of the infrared sensor 26. The point which is controlling is different from the induction heating cooker according to the first embodiment. Also in this embodiment, an infrared sensor 26 formed of a silicon photodiode having the characteristics shown in FIG. 3 is used.

  When the control unit 31 is in a state of heating the object to be heated 20 (heating mode) and the output of the infrared sensor 26 is less than the predetermined value W, the state of not heating the object to be heated 20 (non-heating mode). Or the output (drive current or luminance) of the display LED 27 is lowered or stopped as compared with the case where the output of the infrared sensor 26 is in a state of either the predetermined value W or more.

  In FIG. 6, the flowchart of the light emission control processing of display LED27 by the induction heating cooking appliance of Embodiment 2 of this invention is shown. When the power switch 9 is turned on (S11), the control unit 31 determines whether or not the heated object 20 is currently heated (S12). When the control mode of the control unit 31 is the non-heating mode (No in S12), the display LED 27 is turned on with a large drive current (large output) (S13), and the process returns to step S12.

  When the control mode of the control unit 31 is the heating mode (Yes in S12), that is, when the control unit 31 drives the inverter circuit 28 and supplies a high frequency current to the heating coil 21, the output value of the infrared sensor 26 is predetermined. It is determined whether or not it is equal to or higher than the value W (in this embodiment, 0.2 V and the temperature of the article to be heated 20 is approximately 260 ° C.) (S14). When the output of the infrared sensor 26 is equal to or higher than the predetermined value W (Yes in S14), the temperature of the object to be heated 20 is 260 ° C. or more with the infrared incident region 24 properly covered with the object to be heated 20. It is estimated that the infrared incident area 24 is not properly covered with the object to be heated 20 and the visible light is incident on the infrared sensor 26 when the room is bright. Thus, the display LED 27 is turned on with a large drive current (large output) (S13), and the process returns to step S12.

  When the output of the infrared sensor 26 is less than the predetermined value W (No in S14), the temperature of the object to be heated 20 is less than 260 ° C. with the infrared incident region 24 properly covered with the object to be heated 20. It is estimated that the infrared incident area 24 is not properly covered with the object to be heated 20 when the room is dark, so it is determined that it is unnecessary to increase the output of the display LED 27. In order to extend the life of the LED 27, the output to the display LED 27 is reduced (small output) (S15), and the process returns to step S12.

  Thus, in this embodiment, when the power switch 9 is turned on, the control unit 31 enters a standby mode for waiting for an operation by the heating off / on key 7a. In the standby mode, the inverter 28 is not heated and the display LED 27 is lit with the brightness increased. The user is instructed by an instruction manual or the like so as to cover the display object 27 before starting the heating, or a precaution to that effect is displayed on the top plate 2, or a voice or It is instructed by notification or display in text. Accordingly, the user places the object to be heated 20 above the display LED 27 to cover the display LED 27, and then operates the heating off / on key 7a to start heating. When the heating off / on key 7a is operated and heating is started, it is estimated that the display LED 27 is hidden behind the article to be heated 20, and it is determined that it is not necessary to increase the luminance. Therefore, the control unit 31 is configured to reduce the output to the display LED 27 at the same time as the heating mode in which the inverter 28 is heated and controlled.

  In the present embodiment, even when the control unit 31 is in the heating mode, when the infrared sensor 26 enters visible light and the output of the infrared sensor 26 becomes equal to or greater than the predetermined value W in a bright room, the display LED 27 is displayed. Since the light is lit with a large drive current, the brightness of the display LED 27 is increased so that the user can easily see in a bright room.

  As described above, in the induction heating cooker of the present embodiment, whether or not the control unit 31 is in a state of controlling the heating of the article to be heated 20 and whether the output of the infrared sensor 26 is equal to or greater than a predetermined value W. Since it is possible to control the output of the display LED 27 by determining whether or not the display LED 27 is in a non-heated state where there is a high possibility that the temperature of the display LED 27 is low, the life of the display LED 27 is suppressed. In order to improve the visibility of the person, the output of the display LED 27 is increased, and when the possibility that the room is bright is high, the output of the display LED 27 is increased with priority given to the visibility of the display LED 27 even in a heated state. Accordingly, the display LED can be used to clearly recognize the position of the infrared incident region 24 by the user and prompt the user to place the article 20 to be heated on the infrared incident region 24. The lifetime of the LED can be extended and the reliability of the display LED 27 can be improved.

  In the present embodiment, in step S15, the output of the display LED 27 is set to be small, but the present invention is not limited to this. In step S15, the output of the display LED 27 may be stopped instead of being set to small.

  In the present embodiment, the output of the display LED 27 is based on whether the control unit 31 is in a state of controlling the heating of the article to be heated 20 and whether the output of the infrared sensor 26 is equal to or greater than a predetermined value W. However, the present invention is not limited to this. The control unit 31 may control the output of the display LED 27 based only on whether the object to be heated 20 is being heated, or whether the output value of the infrared sensor 26 is equal to or greater than the predetermined value W. The output of the display LED 27 may be controlled based only on the above. Further, the output of the display LED 27 may be controlled in combination with the configuration described in the first embodiment.

  The induction heating cooker according to the present invention has an effect that the user can strongly recognize the position of the infrared incident region with the light from the visible light display unit, and the visibility and reliability can be enhanced. It is useful for induction heating cookers used for business purposes.

The perspective view of the induction heating cooking appliance by Embodiment 1 of this invention The block diagram of the induction heating cooking appliance by Embodiment 1 of this invention The characteristic figure of the infrared sensor of the induction heating cooking appliance by Embodiment 1 and 2 of this invention The flowchart which shows the light emission control processing of display LED by the induction heating cooking appliance of Embodiment 1 of this invention. The circuit block diagram by the induction heating cooking appliance of Embodiment 2 of this invention The flowchart which shows the light emission control processing of display LED by the induction heating cooking appliance of Embodiment 2 of this invention.

Explanation of symbols

1 outer case 2 top plate 3 left induction heating burner 4 right induction heating burner 5 left induction heating burner display section 6 right induction heating burner display section 7 left induction heating burner operation switch (operation section)
8 Right induction heating burner operation switch (operation unit)
9 Power switch 20 Heated object 21a Inner coil 21b Outer coil 22 Heating coil support base 23 Ferrite 24 Infrared incident area 25 Light guide tube 26 Infrared sensor 27 Display LED (visible light display section)
27a Light emitting area 27b Light guide 28 Inverter circuits 29, 31 Control unit 30 Temperature sensor (temperature detection unit)

Claims (7)

A top plate for placing an object to be heated;
A heating coil that generates an alternating magnetic field to inductively heat an object to be heated;
An infrared sensor that detects the infrared rays emitted from the object to be heated through the infrared incident area formed on the top plate;
A control unit for controlling heating by the heating coil based on the output of the infrared sensor;
A visible light display unit provided below the top plate and arranged so that a light emission state can be visually recognized in the vicinity of the infrared incident region through the top plate;
A temperature detection unit for detecting the temperature of the visible light display unit,
The control unit can reduce or stop the output of the visible light display unit when the temperature detection unit detects a temperature equal to or higher than a predetermined temperature, compared to a case where a temperature lower than the predetermined temperature is detected. Induction heating cooker. The visible light display unit is provided in the vicinity of the heating coil,
The induction heating cooker according to claim 1, wherein the temperature detection unit detects the temperature of the heating coil instead of detecting the temperature of the visible light display unit.   The induction heating cooker according to claim 1 or 2, wherein the temperature detection unit is provided in the vicinity of the visible light display unit and detects an ambient temperature around the visible light display unit. The temperature detection unit is provided in the vicinity of the infrared sensor,
The control unit controls heating by the heating coil by correcting the output of the infrared sensor based on the output of the temperature detection unit so as to reduce the influence of the temperature dependency of the infrared sensor output. The induction heating cooker according to any one of claims 1 to 3, wherein   2. The control unit according to claim 1, wherein the control unit can change the output of the visible light display unit in a plurality of steps so that the output level of the visible light display unit decreases as the temperature detected by the temperature detection unit increases. The induction heating cooking appliance in any one of 4. A top plate for placing an object to be heated;
A heating coil that generates an alternating magnetic field to inductively heat an object to be heated;
An infrared sensor that detects the infrared rays emitted from the object to be heated through the infrared incident area formed on the top plate;
A control unit for controlling heating by the heating coil based on the output of the infrared sensor;
A visible light display unit provided below the top plate, and arranged so that a light emitting state can be visually recognized in the vicinity of the infrared incident region through the top plate;
When the control unit recognizes that the object to be heated is heated by the heating coil, the output of the visible light display unit is greater than when the control unit recognizes that the object to be heated is not heated by the heating coil. An induction heating cooker characterized in that it is possible to reduce or stop the temperature. A top plate for placing an object to be heated;
A heating coil that generates an alternating magnetic field to inductively heat an object to be heated;
An infrared sensor that detects the infrared rays emitted from the object to be heated through the infrared incident area formed on the top plate;
A control unit for controlling heating by the heating coil based on the output of the infrared sensor;
A visible light display unit provided below the top plate, and arranged so that a light emitting state can be visually recognized in the vicinity of the infrared incident region through the top plate;
The control unit increases the output of the visible light display unit when the output of the infrared sensor is greater than or equal to a predetermined output value, compared to when the output of the infrared sensor is less than the predetermined output value. An induction heating cooker characterized by being made possible.

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