JPS5848962Y2 - heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device having a control mechanism for detecting burnt spots on a heated object and automatically heating the object appropriately.

In heating devices such as electric ovens, gas ovens (or grills), microwave ovens, etc., which supply hot air or infrared rays from an electric heater or gas burner to heated objects stored in a heating chamber, Conventionally, the degree of browning of objects is controlled by the user setting the heating time using a timer.

However, the amount and moisture content of the material to be heated, the type of constituent materials,
Furthermore, since the heating time required to achieve the desired browning varies depending on the shape, etc., considerable skill is required to set the heating time, and inappropriate settings often result in over-heating or under-heating the object. Ta.

For this reason, even if a timer is provided, the user must constantly monitor the degree of burntness of the object to be heated, which has the drawback of being inconvenient to use.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to be able to appropriately automatically control the degree of burntness of the heated object.
Further, it is an object of the present invention to provide a heating device that displays an indication that the heating device cannot be used in the case of an object to be heated that cannot be automatically controlled.

In order to achieve the above object, the present invention is equipped with a lamp that irradiates the object to be heated in the heating chamber with visible light and a photosensor (CdS) that receives reflected light from the surface of the object to be heated. The condition of the burnt area is detected, and the heating by hot air or infrared rays from an electric heater, gas burner, etc. is stopped when the appropriate level of browning occurs.In particular, if the reflected light from the surface of the heated object is below a specified level, or When the temperature exceeds a predetermined level, heating by hot air or infrared rays is not performed and it is displayed that burnt spots cannot be detected.

Hereinafter, the present invention will be specifically explained using the drawings.

FIG. 1 is a cross-sectional view of a hot air circulation type microwave oven, which is an embodiment of the present invention.

In the figure, 1 is a heating chamber, 2 is a turntable made of heat-resistant, high-frequency, low-loss material, 3 is an object to be heated, 4 is a door, 5 and 5' are electric heaters, 6 is a high-frequency oscillation tube, 7 is a waveguide, 8 is a motor for turntable 2, 9 is a fan, 10
is a lamp, 11 is a condensing unit, 12 is a mirror, 13 is a lens for adjusting the light receiving range, 14 is a light sensor (CdS), 15 is a control device, 16 is a source device, 17.17' is an air outlet, and 18 is an intake 19 is a punch hole, 20 is heat-resistant glass, and 21 is a buzzer.

Note that the light condensing section 11. The mirror 12 and lens 13 are made of heat-resistant materials.

Now, when the door 4 is opened and the heated object 3 is placed on the turntable 2, the door 4 is closed and the power supply device 16 is driven, the lamp 10 is lit and illuminates the heated object 3. The reflected light is collected by the condensing section 11. The illuminance is sent to the optical sensor 14 via the mirror 12 and lens 13, and the optical sensor 14 sends an illuminance signal to the control device 15.

If this illuminance is within the appropriate level, the control device 15
stores the illuminance of the object to be heated 3 detected by the optical sensor 14 and controls the power supply device 16 .

Meanwhile, the electric heaters 5, 5' and the fan 9 start operating, and hot air is sent into the heating chamber 1 from the air outlet 17, 17'.

Note that the hot air circulates through the suction port 18.

The object to be heated 3 is heated by this hot air.

At the same time, the motor 8 for the turntable 2 operates to further reduce uneven heating of the object to be heated 3.

Eventually, when the surface of the heated object 3 begins to burn, the optical sensor (Cd
S) The illuminance detected by 14 decreases.

When this illuminance reaches a preset value, the control device 15 sends a signal to the power supply device 16.

Upon receiving this signal, the power supply device 16 stops the operation of the electric heaters 5, 5' and the fan 9, and also stops the operation of the motor 8 and lamp 10.

Therefore, heating of the object to be heated 3 is completed.

Next, when detecting burnt spots, if the illuminance from the object to be heated 3 is not within the appropriate level range, that is, if the color of the object to be heated is black, or if an object such as a mirror is accidentally placed on the turntable 2. Let's talk about cases where it is placed on the top.

As mentioned above, when the door 4 is opened and the object to be heated 3 (a matte black object or a mirror-like object) is placed on the turntable 2, the door 4 is closed and the power supply device 16 is activated, the lamp 10 is turned on. The object to be heated 3 is illuminated, and the reflected light from the object to be heated 3 is reflected by the condenser 11. The illuminance is sent to the optical sensor 14 via the mirror 12 and lens 13, and the optical sensor 14 sends an illuminance signal to the control device 15.

The control device 15 determines that this illuminance is at an abnormal level, sounds the buzzer 21, and sends a signal to the power supply device 16.

The power supply device 16 receives this signal and turns off the lamp 10.

Also, at this time, the electric heaters 5, 5' and the fan 9 are temporarily turned on.
works, but immediately stops.

Next, the signal detected by the optical sensor (CdS) 14 is transmitted to the first
The microwave oven shown in the figure will be described.

FIG. 2 shows changes in the resistance value of the optical sensor (CdS) 14 with respect to heating time.

Note that this figure shows a case where the illuminance is within an appropriate level range.

As shown in the figure, when the resistance value R1 at the start of heating (tl-FO) reaches time t3, the object to be heated 3 is burnt, so the illuminance on the surface of the object to be heated 3 decreases.
As a result, the resistance value of the optical sensor (CdS) 14 increases to R3.

Therefore, the degree of burning can be detected based on the resistance value of the optical sensor (CdS) 14.

Note that in the case of a dark heated object, a mirror, etc., the resistance value of the optical sensor (CdS) 14 is approximately constant.

Next, an embodiment of the circuit configuration of the control device 15 of the heating device of the present invention is shown in FIG.

In FIG. 3, 14 is an optical sensor that detects the illuminance (darkness) from the surface of the object to be heated 3, which is a CdS as described above, and 21 is a buzzer.

22 is a DC power supply, 23 is a switch, 25 is a Zener diode, 27 is a non-inverting DC amplifier, 29 is a volume, 30.38.40.52.53.63.64 is a diode, 31.41.49, 50. 51 is a capacitor, 3
2.54.

57, 60 is a comparator, 33 is a positive terminal of the comparator 32, 34 is a negative terminal of the comparator 32, 55 is a positive terminal of the comparator 54, 56 is a comparator 54
58 is the negative terminal of the comparator 57, 59
is the positive terminal of comparator 57, and 61 is the positive terminal of comparator 6.
0 positive terminal, 62 the negative terminal of comparator 60, 3
5 is a relay, 36 is a primary coil of the relay 35, 37 is a secondary contact of the relay 35, 24, 26.28, 39.42 ~
48 is a resistance.

When the switch 23 is turned on, the constant voltage circuit consisting of the resistor 24 and the Zener diode 25 shifts the voltage supplied from the DC power supply 22 to the Cd514 and the resistor 2.
A constant voltage Vz is supplied to the series circuit of 6.

Cd 514 and resistor 26 divide this constant voltage Vz and apply it to the input terminal of non-inverting DC amplifier 27 .

The non-inverting amplifier 27 amplifies the divided voltage in positive phase and outputs the voltage Vl.

Since this voltage (1) changes depending on the degree of light reception by the Cd514, it is an electrical signal that detects the degree of burning of the object to be heated 3, and when the illuminance on the surface of the object to be heated 3 decreases, the Cd514
decreases because the resistance value increases.

Note that the voltage V1 will hereinafter be referred to as a dark spot detection voltage.

The dark spot detection voltage V1 is determined by the resistor 39 and capacitor 41.
Comparator 32 via a low-pass filter consisting of
is applied to the positive input terminal 33 of.

It should be noted that the voltage Vl' applied to this input terminal 33 is called a dark eye detection voltage, like the voltage V1.

The dark spot detection voltage (1) is divided by a series circuit of a resistor 28 and a volume 29.

This divided voltage 5 is input to a capacitor memory circuit consisting of a diode 30 and a capacitor 31.

The capacitor 31 stores the maximum value of the voltage 5,
The memory voltage VM is applied to the negative input terminal 34 of the comparator 32.
supply.

The comparator 32 compares both input voltages V, / and ■4, and outputs a high level output voltage when V,'>Vya, and outputs a low level output voltage when Vr'<VM.
The primary coil 36 and the diode 64 are connected in series.

Note that the diode 38 is for discharging the capacitor 31, and the diode 40 is for discharging the capacitor 41, and when the switch 23 is turned from on to off, the capacitors 31 and 41 are discharged with a time constant smaller than the time constant during charging. Let it discharge.

On the other hand, the dark spot detection voltage 1 is applied to the positive input terminal 55 of the comparator 54 and the negative input terminal 58 of the comparator 57.

A reference voltage VRI obtained by dividing the voltage Vz by the resistors 42 and 43 is applied to the negative input terminal 56 of the comparator 54 .

This reference voltage ■8□ is the upper limit value of the range in which automatic control based on burnt eye detection is possible.

Comparator 54 compares both input voltages 1 and VRI, and outputs a high level output voltage when V+ > VRI.
Further, when V 1 < V R1, a low level output voltage is sent to the buzzer 21 and the resistor 48 through the diode 52.
It is supplied to a time constant circuit consisting of a capacitor 51.

Note that when the switch 23 is turned on, the capacitor 49 receives the applied voltage (V
This is provided to make the voltage RI) higher than the voltage applied to the input terminal 55 (1), and will be described in detail later.

Further, the reference voltage VR2 obtained by dividing the voltage (2) by the resistors 44 and 45 is applied to the positive input terminal 59 of the comparator 57, as described above.

This reference voltage VR□ is the lower limit value of the range in which automatic control based on dark spot detection is possible.

The comparator 57 compares both input voltages 1 and VH2, and outputs a low level output voltage when 1>VH2, and outputs a high level output voltage when V+<VH2 through the buzzer 21. and is supplied to a time constant circuit consisting of a resistor 48 and a capacitor 51.

Note that when the switch 23 is turned on, the capacitor 50 receives the applied voltage (VH
This is provided to make voltage (2) lower than the voltage applied to the input terminal 58 (1), and will be described in detail later.

In addition, diodes 52 and 53 are connected to comparators 54 and 57.
This is provided to make the output side of the circuit independent, and prevents excessive current from flowing in or out.

The tie auto 63 is for discharging the capacitor 51.

Next, the negative input terminal 62 of the comparator 60 has a voltage v
A reference voltage VR3 obtained by dividing 2 by resistors 46 and 47 is applied.

On the other hand, the charging voltage ■□ of the capacitor 51 is applied to the positive input terminal 61.

Comparator 60 compares both input voltages VR3, V□,
Low level voltage when VH3>■1, and VH2<
At VT, a high level voltage is supplied to the series circuit of the primary coil 36 of the relay 35 and the diode 64.

The relay 35 operates when the output voltage of the comparator 32 is at a high level and the output voltage of the comparator 60 is at a low level.
The secondary contact 37 connected to the power supply 16 is turned on so that current flows through the primary coil 36.

When the secondary contact 37 is turned on, the power supply device 16 turns on the lamp 10 and heats the heated object 3 with hot air, as described in FIG. 10 is configured to turn off the light.

In the above circuit, the object to be heated 3 is placed on the saucer 2, the door 4 is closed, and the switch 23 is turned on.

At this point, the capacitor 41 is short-circuited in terms of AC,
The capacitor 31 is not charged and the memory voltage V
M may be set lower than the dark spot detection voltage V1' by the resistor 28 and the volume 29, and the comparator 32 supplies a high level voltage to the primary coil 36 of the relay 35, and the capacitor 51 Comparator 60 supplies a low level voltage to primary coil 36 because it is not being charged.

Therefore, the secondary contact 37 of the relay 35 turns on, the power supply 16 operates, the lamp 10 lights up, and the fan 9
, the electric heaters 5, 5', and the turntable motor 8 start operating.

At this time, the resistance value of Cd514 decreases from a high resistance, and the dark spot detection voltage 1 increases.

This increase reaches its peak in about 10 seconds at the latest.

Incidentally, the time constants of the capacitor 49 and the resistor 42, 43, and the time constants of the capacitor 50 and the resistor 44, 45 are set slightly larger than the time at which this dark spot detection voltage (1) reaches its peak.

Therefore, at this point, the outputs of the comparators 54 and 57 are at a low level, the buzzer 21 does not sound, and the output of the comparator 60 also remains at a low level.

Next, when the illuminance due to the reflection of the heated object vD3 is within the appropriate level range (not a mirror or an eyelid-black object to be heated), the comparators 57 and 54 The output of V T <
It becomes VR3.

As a result, the output of the comparator 60 also maintains a low level voltage.

Eventually, when the object to be heated 3 begins to burn, the illuminance from the surface of the object to be heated 3 begins to decrease, and the resistance value of Cd514 gradually increases.

For this reason, the dark spot detection voltage 1 gradually decreases, and the voltage V similarly reaches its peak and then decreases.
Diode 30 is cut off and memory voltage VM is stored in capacitor 31.

Furthermore, when the burnt state progresses and the burnt detection voltage V1 becomes smaller than the memory voltage VM, the comparator 32 changes the high level voltage supplied to the primary coil 36 of the relay 35 to a low level voltage. Invert.

Therefore, since the secondary contact 37 is turned off, the heating by hot air ends.

Furthermore, driving of the lamp 10 and motor 8 is also stopped.

On the other hand, if the illuminance reflected by the heated object 3 is not within the appropriate level range (in the case of a mirror or an eyelid heated object), VRI < Vl or V 1 < VR2, so the comparator The output of 57 or 54 is inverted from a low level voltage to a high level voltage.

Therefore, the buzzer 2
Electric current flows through 1 and produces sound.

Similarly, capacitor 51 is charged via resistor 48.

As a result, V T > V R3 and comparator 6
The output of 0 becomes a voltage from a low level to a high level.

Therefore, even if the output of the comparator 32 is a high level voltage, the secondary contact 37 of the relay 35 is turned off, and heating by hot air is stopped.

Further, the driving of the lamp 10 and the motor 8 is also stopped. As described above, the present invention makes it possible to automatically control burnt spots that previously relied on visual perception.In particular, when the illuminance of the object to be heated is not within an appropriate level, a buzzer can be used to display the problem. This is particularly effective in terms of safety, since heating is stopped immediately.

In addition, in this example, when the illuminance of the object to be heated is within an appropriate level range, the heating is stopped when the signal from the optical sensor reaches a preset value. The present invention is also effective when changing the degree of heating (for example, high-frequency heating) or the degree of heating.

Furthermore, in this embodiment, when the illuminance of the object to be heated is not within the appropriate level range, a case has been described in which a sound is displayed using a buzzer, but the present invention is also effective when displaying light using a lamp or the like. It is.

Furthermore, in this embodiment, the present invention is also effective even if the contacts of the relay 35 are connected in parallel with the switch 23 as two contacts to form a self-holding circuit.

In addition, in this example, a light source (lamp) is installed near the outside of the heating chamber.
Although the case where the heating chamber is provided has been described, the present invention is effective even if it is provided in a part of the heating chamber.

Furthermore, the present invention not only measures safety by detecting whether the illuminance of the object to be heated is within an appropriate level range, but is also effective against short-circuit and open-circuit failures of the optical sensor (CdS).

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a configuration example (cross section) of the heating device of the present invention, Fig. 2 is a diagram showing the resistance change of the optical sensor (CdS) as the burnt surface of the heated object progresses, and Fig. 3 is 1 is a diagram showing an example of a circuit configuration of a control device of the present invention. In the figure, 1... heating chamber, 2... turntable, 3... object to be heated, 5, 5'...
...Electric heater, 6...High frequency oscillation tube, 9
...Fan, 10...Lamp, 11.
...Concentrator, 12...Mirror, 13...
... Lens, 14 ... Optical sensor (CdS), 1
5...control device, 16...power supply device,
22...DC power supply, 23...Switch, 27...Non-inverting amplifier, 28...
Resistance, 29... Volume, 30...
Diode, 31... Capacitor, 32, 54
, 57.60... Comparator, 35...
··relay

Claims (1)

[Scope of utility model registration request] In a device having a mechanism for heating an object stored in a heating chamber by supplying hot air or infrared rays from an electric heater or gas burner to the object to be heated, the object to be heated in the heating chamber is irradiated with visible light. A control device is provided with a light source and an optical sensor that detects reflected light from the surface of the heated object, the optical sensor detects a brown mark on the heated object, and the control device receives the detection signal and controls the heating mechanism. and a display device, wherein the control device causes the display device to display that burn mark detection is impossible when the detection signal is not within a predetermined level range.