JPS60152827A - Automatic roaster - Google Patents

Abstract

PURPOSE:To enable to obtain an identical roasting state always even if roast is made continuously and the variation occurs on power source voltage, by turning a heater OFF by comparing an output of a temperature detecting device to which constgant voltage is applied by a constant voltage generating device with that of a timing device. CONSTITUTION:As the temperature in the inside of a heating chamber is high at roast after the second roast, a resisting value of a negative-characteristic thermistor 16 is declined and as electric potential of a gate terminal of a reverse inhibition thyristor (PUT)10 of an N gate 3 terminal is low, the PUT10 is turned ON and a heater 2 is made to turn OFF earlier than a previous roasting time. As a resistor 19 and the negative-characteristic thermistor 16 are kept at constant voltage by a Zener diode 20 though a charging rate of a condenser to be charged is varied similarly to a heat value of a heater 3 when the voltage of an AC power source 1 has varied, detecting capacity of the negative-characteristic thermistor 16 does not vary at all. In other words, as the charging rate to the condenser 7 is declined also even if the heat value of the heater 3 was declined also through a decline of the voltage of the AC power source 1, a period turning the heater 3 ON becomes long. An identical roasting state is obtained always in any case like this.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an automatic roasting device for baking bread and the like.

Conventional Structure and Problems Generally, in this type of roasting apparatus, after roasting has started, a certain period of time has been measured using a resistor and a capacitor, and then the heater is turned off.

By the way, when roasting is repeated in such an automatic roasting device, the residual heat in the casing gradually increases the second and third time, and if roasting is continued for the same amount of time, the residual heat will be higher compared to the first roasting. During the second roasting process, the baked goods such as bread become darker in color.

For this reason, automatic roasting apparatuses have been devised that shorten the energization time of the heater during subsequent roasting, that is, the roasting time, compared to the initial roasting.

Hereinafter, such an automatic roasting device will be explained using the drawings. In FIG. 1, 1 is an AC power source, 2 is a switch for turning on and off a heater 3 installed in the heating chamber, 4 is a resistor that together with a diode 6 and a capacitor 6 constitute a rectifier circuit, and 7 is a resistor 8 connected to the capacitor 6. , a capacitor 10 as a timer connected via a diode 9 has its anode terminal connected to the connection point of the diode 9 and the capacitor 7 via a resistor 11, and its gate terminal connected to both ends of the capacitor 6. The N-gate 3-terminal reverse blocking thyristor (hereinafter referred to as SCR) 14 is connected to the connecting point of the resistor 12゜13, and its cathode terminal is connected to the gate terminal of a P-gate 3-terminal reverse blocking thyristor (hereinafter referred to as SCR) 14. (called PUT). A relay coil 16 is connected to the 5CR14, and is activated when the 5CR14 is turned on to turn off the switch 2. With this configuration, when the user turns on the switch 2, the heater 3 generates heat and the capacitor 7 is charged. As the capacitor 7 is charged, the potential of the anode terminal of PUTlo increases. On the other hand, a voltage divided by resistors 12 and 13 is applied to the gate terminal of PUT10.
PUTlo is turned on when the potential of the anode terminal becomes higher than the potential of the gate terminal.

When P'UT10 is turned on, the charge charged in capacitor 7 is transferred to 5CR1 via the cathode terminal of PUTlo.
4 and turns on 5CR14. 5C
When R1'4 is turned on, the relay coil 16 connected in series with it is also turned on, turning off the switch 2 which was latched in the on state, and also turning off the heater 3.

Also, if you start the second roasting immediately after the first roasting ends, the temperature of the heating chamber will have risen during the first roasting, so the second roasting time will be longer than the first roasting time. Time must also be shortened. For this reason, if the resistor 11 is inserted into the discharge circuit of the capacitor 7 and the resistance value is increased, it will take time to discharge the capacitor 7, and even after the heater 3 is turned off, the capacitor 7 will remain charged. If the time from the start of the second roasting until the capacitor 7 is charged with electric charge is short, the same roasting color as the first roasting can be obtained.

However, with this configuration, even when roasting for the third consecutive time,
As with the second roasting, there is a charge left in the capacitor 7, so the third and second roasting times will be the same, but the temperature in the heating chamber during the third roasting will be the same as the second roasting time. , so the third roasting must be shortened.

If roasting was repeated three or four times in a row in this way, even though the temperature in the heating chamber was high, the roasting would take a long time, resulting in overcooking.

In order to solve this problem, it has been considered to use a temperature detection means to control the heater according to the temperature inside the heating chamber. Hereinafter, such an automatic roasting device will be explained. Note that the same members as in FIG. 1 are given the same numbers and their explanations will be omitted.

In FIG. 2, reference numeral 16 denotes a negative characteristic thermistor as temperature detection means, and a partial voltage between the resistor 12 and the negative characteristic thermistor 16 is applied to the gate terminal of PUTlo. Also 17
is a Zener diode, which applies a constant voltage to the resistor 8, capacitor 7, resistor 12, and thermistor 16.

With this configuration, roasting is performed 3 times and 4 times in succession,
Even if roasting is performed with the temperature in the heating chamber rising,
Corresponding to the temperature in the heating room, the resistance value of the dog characteristic thermistor 16 becomes smaller and the potential of the gate terminal of PUTlo becomes lower, so the time that the heater 3 is on becomes shorter.
You will always get the same roasted state.

However, in this configuration, when the voltage of the AC power source 1 changes, the amount of heat generated by the heater 3 changes.

This fluctuation in the amount of heat generated can also be detected by the negative characteristic thermistor 16, but since the negative characteristic thermistor 16 detects voltage fluctuations via the temperature in the heating chamber, the negative characteristic thermistor 16 alone is insufficient, and the voltage of the AC power supply 1 is The roasting condition was changing due to the fluctuation.

Purpose of invention In view of the above problems, this invention is the third consecutive invention.

To provide an automatic roasting device that can always obtain the same roasted state even when roasting is performed for the fourth time and even if the power supply voltage fluctuates.

Structure of the Invention In order to achieve the above object, the automatic roasting apparatus of the present invention includes: a heater that heats the inside of the heating chamber; an energization start means that controls energization to the heater; and a temperature detection means provided within the heating chamber. A constant voltage generating means for applying a constant voltage to the temperature detecting means, a time limit means operated by the energization start means, a comparator for comparing the performance of the rH dust detecting means and the time limit means, and this comparator. and energization stopping means for turning off the heater by the output of the heater. With this configuration, it is possible to always obtain the same roasted state even if roasting is performed continuously or even if there are fluctuations in the power supply voltage.

DESCRIPTION OF EMBODIMENTS An embodiment of the automatic roasting apparatus of the present invention will be described below with reference to FIG.

Note that the same numbers as those in the conventional example are given the same numbers, and the explanation thereof will be omitted.

The negative characteristic thermistor 16 has a resistor 18 across the capacitor 60.
．． It is connected via a resistor 19. Further, the gate terminal of PUTlo is connected to the connection point between the resistor 19 and the negative characteristic thermistor 16, and its anode terminal is connected to the connection point between the resistor 8 provided at both ends of the capacitor 6 and the capacitor T. Further, a Zener diode 20 is connected to both ends of the resistor 19 and the negative characteristic thermistor 16 to maintain the resistor 19 and the negative characteristic thermistor 16 at a constant voltage.

To explain the operation of this configuration, when the switch 2 is turned on, the heater 3 generates heat and electric charge accumulates in the capacitor 7. As a result, the potential of the anode terminal of P UTlo increases, and the resistor 19 and negative characteristic thermistor 16
PUTlo turns on when the potential of the anode terminal becomes higher than the potential of the gate terminal determined by the partial voltage of 5C.
R14 is turned on, relay coil 15 is also turned on, and switch 2 is turned off.

When roasting is subsequently performed for the second time, the temperature in the heating chamber reaches a high level, so the resistance value of the negative custom-made thermistor 16 decreases. In other words, since the potential of the gate terminal of PUTlo is low, PUTlo is turned on earlier than during the first roasting, and the heater 3 is turned off earlier. When roasting for the third and fourth time, the roasting time is similarly determined according to the temperature in the heating chamber, so that the same roasted state can always be obtained.

Furthermore, when the voltage of the AC power supply 1 fluctuates, the amount of heat generated by the heater 3 also fluctuates, and the rate at which the capacitor is charged also fluctuates. However, since the resistance 19 and the negative characteristic thermistor 16 are kept at a constant voltage by the Zener diode 20, the detection ability of the negative characteristic thermistor 16 does not change at all. In other words, even if the voltage of the AC power source 1 decreases and the amount of heat generated by the heater 30 decreases, the charging speed of the capacitor 7 will also decrease, and the time that the heater 3 is on will also become longer. On the other hand, even if the voltage increases and the amount of heat generated by the heater 3 increases, the time that the heater 3 is on is short, and the same roasting state can always be obtained.

Effects of the Invention As is clear from the description of the above embodiments, the automatic roasting apparatus of the present invention always produces the same results even when roasting is continuous or when there are fluctuations in the power supply voltage. A roasted state can now be obtained, which has great practical effects.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a general automatic roasting device, Figure 2 is a circuit diagram of a rotary automatic roasting device, and Figure 3 is a circuit diagram of an automatic roasting device that is an embodiment of the present invention. It is. 2...Switch, 3...Heater, 7
...Capacitor, 10...N gate 3
Terminal reverse blocking thyristor, 16... Relay coil, 16... Negative characteristic thermistor, 2o River... Zener diode.

Claims (1)

[Claims] A heater that heats the inside of a heating chamber, an energization start means that controls energization to the heater, a temperature detection means provided in the heating chamber, a constant voltage generation means that applies a constant voltage to the temperature detection means, and the energization An automatic roasting device comprising: a timer actuated by a start means; a comparator that compares the outputs of the temperature detection means and the timer; and an energization stopper that turns off the heater based on the output of the comparator.