JPH0117217Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic cooking device mainly for focus control when continuously cooking in a toaster, toaster oven, or the like.

Conventional devices of this type have been developed that use mechanical or electronic timers to control the time, but due to the influence of the temperature inside the cooking chamber, the time required for the first and second cooking times is the same. Therefore, there was a problem that the focus tended to become a little darker after the second time because the temperature was higher, and a constant focus was not necessarily obtained.

The present invention aims to improve such drawbacks and provide an automatic cooking device that is controlled to maintain a constant focus regardless of the number of times it is cooked using two capacitors arranged in parallel via a diode.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 is a configuration circuit diagram of an automatic cooking device, 38,
39 is a terminal connected to the power source 40. 1,8
is switch A that operates in conjunction with push button 3,
When the push button 3 of the switch B is set, the switches A and B are closed and the heating element 2 is energized. A spring 4 and a magnet 5 are attached to the push button 3, and are attracted to a fixed yoke 6 when set. This yoke 6
The excitation coil 7 is wound around the push button 3, the spring 4, the switch A1, and the switch B.
8, a yoke 6, a magnet 5, and an excitation coil 7 are integrated to form a self-resetting switch.

When the push button 3 is set, a constant voltage is applied to the capacitor 18 via the resistor 14, diode 16, and voltage regulator diode 17. The constant voltage is divided by a resistor 19, a variable resistor 36, and a resistor 20 to set a voltage value that determines focus adjustment, and is supplied to the gate G of the switch element 21.

Also, a first charging circuit charges the capacitor A23 via the diode 27 and the resistor 28, and a second charging circuit charges the capacitor B24 via the diode 25.
It constitutes the charging circuit. One terminal of the capacitor A23 of the first charging circuit is connected to the anode side of the switch element 21, and the cathode side is connected to the resistor 22.
It is connected to terminal 39 via. One end of the resistor 22 is connected to the base of the transistor 11 to drive the excitation coil 7 via the switch B8, but this drive current is supplied from a power supply circuit consisting of the resistor 9, diode 10, capacitor 13, and voltage regulator diode 12. has been done.

The capacitor B24 of the second charging circuit is discharged through a circuit including a diode 26 and a resistor 35 only when no current is applied. For this purpose, a changeover switch circuit is provided which turns on the transistor 29, causes current to flow through the diodes 31, 37, and the resistor 30, and raises the cathode voltage of the diode 26, thereby preventing discharge to the resistor 35. Capacitor 3 is used to turn on transistor 29 when energized.
4. A base current is passed through the transistor 29 by a circuit consisting of resistors 32 and 33.

Next, the operation of the electric circuit of the cooking apparatus constructed as described above will be explained with reference to FIG. When the push button 3 is set, the yoke 6 is attracted to the magnet 5, switches A1 and B8 are closed, the heating element 2 starts to be energized, and the resistor 28 is closed.
A pulsating current flows through the capacitors A23 and B24, and charging begins. In other words, the base current flows to the transistor 29 via the resistor 32, turning it on.
As a result, the voltage Vd becomes high level and reverse biases the diode 26. Therefore, there is no discharge to the resistor 35, and the capacitors A23 and B2
4 are electrically connected in parallel, the voltage of Va increases together with the voltage of Vb, which is approximately the same and has a potential difference of the forward voltage of the diode 25, as shown in FIG.

On the other hand, a constant voltage Ve obtained from a power supply circuit consisting of a diode 16, a low resistor 15, a constant voltage diode 17, and a capacitor 18 is divided by resistors 19, 20 and a variable resistor 36 to generate a voltage Vc corresponding to the focus setting. is the gate G of the switch element 21
Since the voltage of capacitor A23 is
When Va reaches Vc + VT (VT is the gate voltage),
The switch element 21 is turned on, and part of the anode current flows as the base current of the transistor 11, and the transistor 11 is also turned on at the same time, driving the exciting coil 7. Therefore, the magnet 5 becomes a reverse magnetic field via the yoke 6, so the magnet 5
moves away from the yoke 6, the switch A1 and the switch B8 are turned off, the electricity supply to the heating element 2 is interrupted, and the cooking operation is completed.

Even after turning off the switch in preparation for next cooking, only capacitor B24 and transistor 29 remain active.
Since it is in the OFF state, Vb gradually decreases from the time t1 through the diode 26 and the resistor 35 as shown in Figure ₂ , but the voltage of the capacitor A23
Va is instantaneously discharged through the switch element 21, and reaches a value close to 0 at time _t1 .

When the second cooking starts at time _t2 , when the push button 3 is set in the same way as the first cooking, the switch A1 and the switch B8 are closed and the heating element 2 starts to be energized. However, capacitor B
24 has a residual voltage of Vb, so the ripple current flowing through the resistor 28 charges only the capacitor A23. In other words, the voltage Va is Vb + V _AK = Va (V _AK
is the forward voltage of diode 25) until time _t3 , when diode 25 is in a reverse bias state and capacitor B24 is not charged, so the Va voltage between _t2 and _t3 rises faster than the first time. go. In other words, the time constant is becoming smaller. In addition, since the transistor 29 is always in the ON state when energized,
The cathode voltage Vd of the diode 26 becomes a high level voltage, and this diode 26 also becomes reverse biased, so the capacitor B24 is not charged, and the voltage Vb between t ₂ and _{t 3} in FIG. 2 is almost constant. Become.

Next, when Va reaches Vb + V _AK at time t ₃ , diode 25 becomes forward biased and capacitor B24 is also charged, so the voltage of Va after t ₃ rises at the same speed as the first time. I will go there. In other words, the time constant is the same as the first time.
When the voltage Va of the capacitor A23 reaches Vc+V+ (VT is the gate voltage) at _t4 , the switch element 21
The transistor 1 becomes ON state and the same as the first time.
1 is also turned on at the same time, driving the excitation coil 7, turning off switches A1 and B8, and heating element 2.
interrupts power supply to.

As described above, according to the present invention, of the two capacitors A and B involved in timer operation that are arranged in parallel via a diode, one capacitor B is discharged via the diode and resistor when no current is applied. When resetting, the timer operation is performed while holding the voltage of capacitor B and charging only the other capacitor A, and when the holding voltage of capacitor B is reached, both capacitors A and B are charged, and this charging characteristic is By changing the cooking time midway through, the second cooking time is made shorter than the first cooking time, so the influence of the initial temperature inside the refrigerator can be reduced, and a characteristic that the browning becomes constant can be obtained. Also, the pause time (t ₂
Since the cooking operation time is proportional to -t ₁ ) so that the focus is almost constant, the effect of correcting the cooking time with respect to the rest time can also be obtained. Note that when setting the focus, the Vc voltage changes using a variable resistor, so the cooking time can be set freely. Furthermore, the time constant for charging is automatically changed from the second time onward, and the state at the start point is stored as a voltage in capacitor B, so that the focus can be corrected at all times. It is possible to provide an automatic cooking device that can achieve a certain focus.

[Brief explanation of the drawing]

FIG. 1 is a configuration circuit diagram of an automatic cooking apparatus showing an embodiment of the present invention, and FIG. 2 is an operation explanatory diagram of the configuration circuit similarly shown in FIG. 1. 1... Switch A, 2... Heating element, 21... Switch element, 23... Capacitor A, 24... Capacitor B, 25... Diode.

Claims (1)

[Scope of utility model registration request] A timer circuit is constituted by a charging circuit in which two capacitors A23 and B24 are connected in parallel through a diode 25, and a switch element 21 operated by both voltages of the one capacitor. A switch A1 is provided which controls the heating element 2 by the operation of the switch A1, a discharge circuit is provided in one of the capacitors A23 and B24, and a changeover switch circuit is provided which operates the discharge circuit only after the switch A1 operates. Features an automatic cooking device.