JPS6367683B2

JPS6367683B2 -

Info

Publication number: JPS6367683B2
Application number: JP15292280A
Authority: JP
Inventors: Masaki Nakamura; Haruo Terai; Shigeo Hamaoka; Katsunori Zaizen
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1980-10-29
Filing date: 1980-10-29
Publication date: 1988-12-27
Also published as: JPS5775331A

Description

[Detailed description of the invention]

本発明は交流電源に接続されるCR積分回路の
コンデンサの充電時間を利用して、ヒータへの通
電を所定時間後に遮断する加熱機器の制御回路に
関するもので、電源電圧変動によるヒータへの通
電時間の補正を加熱機器において最適となるよう
に制御補正することを目的とする。従来の電源電圧変動に対するヒータへの通電時
間の補正は、第１図に示すようなCRタイマ回路
が一般的である。以下、従来例を第１図に基づい
て詳述する。第１図において、１は交流電源で、電源スイツ
チ２を介してヒータ２０が接続されている。この
ヒータ２０と並列に接続されるCR積分回路３は、
ダイオード４、抵抗５、コンデンサ６の直列回路
より構成され、スイツチ２が閉じられると、コン
デンサ６は、電源電圧で、かつ半波で充電され
る。また、ヒータ２０と並列に定電圧回路７が接
続されており、ダイオード９、抵抗２１およびコ
ンデンサ８により交流電源１を直流電源に変換
し、コンデンサ８の両端に接続した定電圧ダイオ
ード９により定電化されている。この定電圧ダイ
オード９の電圧を抵抗１０，１１により分圧し、
基準電圧を発生させている。この抵抗１０，１１
の接続点の基準電圧とCR積分回路３のコンデン
サ６の電圧とを比較する比較器であるPUT１２
を備えている。このPUT１２のカソード端子１
３はソレノイド１８への通電制御を行うサイリス
タ１９のゲートに出力されている。ソレノイド１
８は、スイツチ２を開状態にする動作を行う。この構成においてスイツチ２を閉じると、前述
したように、CR積分回路３のコンデンサ６の電
圧は徐々に上昇してゆき、基準電圧に達すると
PUT１２はオンになり、コンデンサ６の充電電
荷を放出しカソード端子１３にパルス出力が得ら
れる。この出力によりサイリスタ１９がオンして
ソレノイド１８に電流が流れるため、スイツチ２
が開く。すなわち、コンデンサ６への充電時間に
よりヒータ２０への通電時間を制御する。この従来例において、基準電圧は定電圧ダイオ
ード９により定電圧化しているので、電源電圧が
高くなると、コンデンサ６の充電速度が速くな
り、コンデンサ６の電圧が基準電圧に達するまで
の時間が速くなり、よつて、PUT１２がオンす
るまでの時間が短くなる。また逆に電源電圧が低
くなると、PUT１２がオンになるまでの時間が
長くなる。これらの変化の割合は、CR積分回路
３に、電源電圧の変動をそのまま加えているの
で、電源電圧変動率と時限の変動率の関係は第２
図に示すように、ほぼ逆比例の関係がある。第２
図に、従来例の回路を実験室で試作し、実験した
結果を実線で示す。実験結果によれば、電源電圧
を100Vから−15％変化させるとスイツチ２をオ
ンしてからヒータ２０の通電を停止するまでの時
限は、＋18.7％、また、電源電圧を＋15％変化さ
せるとその時限は−15.2％変化する。しかしながら、この従来例をオーブントースタ
等の加熱機器に応用すると、調理物の仕上りは、
その調理物に与えられたトータル熱量によつて決
まるので、電源電圧に対し逆比例の関係でヒータ
２０への通電時限を変化させても充分な補正がで
きず、オーブントースタでパンを焼くと、電源電
圧変動により、焼色がかなり異なる。すなわち、電源電圧100Vにおける入力W₀で、
ヒータ２０へt₀秒通電して所定の焼色にパンを焼
くことができるとすると、そのときのトータル熱
量は、 W₀t₀＝V² ₀t₀／Ｒ（Ｒはヒータ２０の抵抗値）となる。このトータル熱量W₀t₀を電源電圧がＶ
に変動した場合にでも得ようとすれば、そのとき
のヒータ２０への通電時間ｔの変動率を計算して
みると、 V² ₀t₀／Ｒ＝V²t／Ｒ ∴ｔ／t₀＝V² ₀／V²＝（１／Ｖ／V₀）となり、その計算結果を下表に示す。 The present invention relates to a control circuit for a heating device that utilizes the charging time of a capacitor in a CR integrating circuit connected to an AC power source to cut off power to a heater after a predetermined period of time. The purpose is to control and correct the correction so that it is optimal in heating equipment. Conventionally, a CR timer circuit as shown in FIG. 1 is commonly used to correct the energization time to the heater in response to power supply voltage fluctuations. Hereinafter, a conventional example will be explained in detail based on FIG. In FIG. 1, reference numeral 1 denotes an AC power source, to which a heater 20 is connected via a power switch 2. In FIG. The CR integration circuit 3 connected in parallel with this heater 20 is
It is composed of a series circuit of a diode 4, a resistor 5, and a capacitor 6, and when the switch 2 is closed, the capacitor 6 is charged with the power supply voltage and in half waves. Further, a constant voltage circuit 7 is connected in parallel with the heater 20, and a diode 9, a resistor 21, and a capacitor 8 convert the AC power source 1 into a DC power source, and a constant voltage diode 9 connected to both ends of the capacitor 8 provides a constant voltage. has been done. The voltage of this voltage regulator diode 9 is divided by resistors 10 and 11,
Generates a reference voltage. This resistance 10, 11
PUT12 is a comparator that compares the reference voltage at the connection point of
It is equipped with Cathode terminal 1 of this PUT12
3 is output to the gate of the thyristor 19 which controls the energization of the solenoid 18. solenoid 1
8 performs an operation to open the switch 2. When the switch 2 is closed in this configuration, the voltage of the capacitor 6 of the CR integration circuit 3 gradually increases, and when it reaches the reference voltage, as described above.
PUT 12 is turned on, discharges the charge stored in capacitor 6, and a pulse output is obtained at cathode terminal 13. This output turns on the thyristor 19 and current flows through the solenoid 18, so the switch 2
opens. That is, the time for energizing the heater 20 is controlled by the time for charging the capacitor 6. In this conventional example, the reference voltage is regulated by the voltage regulator diode 9, so as the power supply voltage increases, the charging speed of the capacitor 6 becomes faster, and the time it takes for the voltage of the capacitor 6 to reach the reference voltage becomes faster. , Therefore, the time it takes for PUT 12 to turn on becomes shorter. Conversely, when the power supply voltage decreases, the time it takes for the PUT 12 to turn on becomes longer. These rates of change are calculated by directly adding the fluctuations in the power supply voltage to the CR integration circuit 3, so the relationship between the power supply voltage fluctuation rate and the time period fluctuation rate is the second one.
As shown in the figure, there is a nearly inversely proportional relationship. Second
In the figure, a conventional circuit was prototyped in a laboratory, and the experimental results are shown by solid lines. According to the experimental results, when the power supply voltage is changed by -15% from 100V, the time period from turning on switch 2 to stopping energization of heater 20 is +18.7%, and when the power supply voltage is changed by +15%. and its time period changes by -15.2%. However, if this conventional example is applied to a heating device such as a toaster oven, the finish of the cooked food will be
Since it is determined by the total amount of heat given to the food, it is inversely proportional to the power supply voltage, so even if you change the time limit for energizing the heater 20, it cannot be sufficiently compensated for. The browning color varies considerably depending on power supply voltage fluctuations. That is, at an input W ₀ at a power supply voltage of 100V,
Assuming that it is possible to bake bread to the desired brown color by applying electricity to the heater 20 for t ₀ seconds, the total amount of heat at that time is W ₀ t ₀ =V ² ₀ t ₀ /R (R is the resistance value of the heater 20 ) becomes. This total amount of heat W ₀ t ₀ is determined by the power supply voltage V
If you want to obtain the result even if it fluctuates, calculate the fluctuation rate of the energization time t to the heater 20 at that time, and get V ² ₀ t ₀ /R=V ² t/R ∴t/t ₀ =V ² ₀ /V ² =(1/V/V ₀ ), and the calculation results are shown in the table below.

【表】これを図示すると、第２図の点線のようにな
る。従つて、トータル熱量補正を行うためには、
電源電圧変動率に対して、逆２乗例以上のヒータ
２０への時限変化率をもたせる必要があり、従来
の単なる逆比例の補正では十分にパンの焼色を一
定に保つことができなかつた。以下、本発明の一実施例を第３図により説明す
る。なお、第１図の従来と同一部品に同一番号を
付して説明を省略する。第３図において、１４は
ヒータ２０に並列接続したトランスの１次側、１
５は２次側である。１６はブリツジダイオードで
あり、トランス１５の２次側出力を整流し、コン
デンサ１７で平滑し、分割抵抗１０の両端に印加
し、定電圧ダイオード９の電圧から電源電圧変動
を差し引く引算回路を構成している。上記構成において、電源スイツチ２が閉じられ
ると、ヒータ２０は通電され、CR積分回路３の
コンデンサ６には半波電圧が充電される。そし
て、従来例で説明したようにコンデンサ６の充
電々圧がPUT１２のゲート電圧Ｇに達すると、
PUT１２はオンになり、カソード端子１３には
パルス出力がでる。従つて、サイリスタ１９はオ
ン状態になり、ソレノイド１８には電流が流れ、
電源スイツチ２を開き、ヒータ２０への電流をし
や断する。ここで、電源電圧が変動した場合、引算回路１
６は、定電圧ダイオード９で決まる一定電圧と逆
方向の電圧を発生するようにブリツジダイオード
により整流しており、しかも、交流電源１の電圧
に比例した電圧（分割抵抗１０の両端の電圧）値
が発生させるための、定電圧回路７の定電圧から
交流電源１に比例した電圧を差し引くことにな
る。よつて、PUT１２のゲート電圧は交流電源
１の電圧が高いと低く、また逆に交流電源１の電
圧が高いと高くなる。例えば、100Vにおける引算回路１６に発生す
る分割抵抗１０の両側の電圧を16V、定電圧ダイ
オード９の電圧を20Vとすれば、電源電圧変動に
対するPUT１２の基準電圧の変化は下表のよう
になる。[Table] If this is illustrated, it will look like the dotted line in Figure 2. Therefore, in order to perform total heat correction,
It is necessary to provide a time-limited rate of change to the heater 20 that is greater than the inverse square of the fluctuation rate of the power supply voltage, and it has not been possible to sufficiently keep the browning of the bread constant with the conventional simple inverse proportional correction. . An embodiment of the present invention will be described below with reference to FIG. It should be noted that the same parts as those in the prior art shown in FIG. 1 are given the same numbers and their explanations will be omitted. In FIG. 3, 14 is the primary side of the transformer connected in parallel to the heater 20;
5 is the secondary side. A bridge diode 16 rectifies the secondary output of the transformer 15, smooths it with a capacitor 17, applies it to both ends of the dividing resistor 10, and provides a subtraction circuit that subtracts power supply voltage fluctuations from the voltage of the constant voltage diode 9. It consists of In the above configuration, when the power switch 2 is closed, the heater 20 is energized and the capacitor 6 of the CR integration circuit 3 is charged with a half-wave voltage. Then, as explained in the conventional example, when the charging voltage of the capacitor 6 reaches the gate voltage G of the PUT 12,
PUT 12 is turned on and a pulse output is output to cathode terminal 13. Therefore, the thyristor 19 is turned on, and current flows through the solenoid 18.
Open the power switch 2 to cut off the current to the heater 20. Here, if the power supply voltage fluctuates, the subtraction circuit 1
6 is rectified by a bridge diode so as to generate a voltage in the opposite direction to the constant voltage determined by the constant voltage diode 9, and a voltage proportional to the voltage of the AC power source 1 (voltage across the dividing resistor 10). To generate the value, a voltage proportional to the AC power source 1 is subtracted from the constant voltage of the constant voltage circuit 7. Therefore, the gate voltage of the PUT 12 becomes low when the voltage of the AC power supply 1 is high, and conversely becomes high when the voltage of the AC power supply 1 is high. For example, if the voltage on both sides of the dividing resistor 10 generated in the subtraction circuit 16 at 100V is 16V, and the voltage of the constant voltage diode 9 is 20V, the change in the reference voltage of the PUT 12 with respect to power supply voltage fluctuations will be as shown in the table below. .

【表】すなわち、電源電圧変動±15％に対して、基準
電圧の変動は±60％となり３倍に増巾することが
できる。なお、この増巾率は定電圧ダイオード９
の電圧を適当に選ぶことにより、任意に設定でき
る。従つて前述した２乗比例の近い時限の変化率
をもたせることができる。本発明によるCRタイマ回路をオーブントース
タに応用し、パンの培焼実験を行つた結果、電源
電圧の変動割合以上にヒータ通電時間が変化し、
パンの焼色が殆んど変化しないという良好な結果
を得た。なお、第３図において、CR積分回路３を定電
圧回路に接続し、定電圧充電を行つても同様な効
果を得ることができる。以上のように本発明は複雑な回路を必要とせ
ず、簡単な構成であるため、安価にかつ、信頼性
が高い補正が実現でき、実用的価値が大である。[Table] In other words, for a power supply voltage variation of ±15%, the reference voltage variation is ±60%, which can be amplified three times. Note that this amplification rate is determined by the constant voltage diode 9
It can be set arbitrarily by selecting an appropriate voltage. Therefore, it is possible to provide a time-limited rate of change close to the square proportionality described above. As a result of applying the CR timer circuit according to the present invention to a toaster oven and performing a bread baking experiment, the heater energization time changed more than the fluctuation rate of the power supply voltage.
Good results were obtained in that the baked bread color hardly changed. In addition, in FIG. 3, the same effect can be obtained even if the CR integration circuit 3 is connected to a constant voltage circuit and constant voltage charging is performed. As described above, since the present invention does not require a complicated circuit and has a simple configuration, it is possible to realize correction with high reliability at low cost, and has great practical value.

[Brief explanation of drawings]

第１図は従来例を示すCRタイマ回路、第２図
は電源電圧と時限の関係を示す特性図、第３図は
本発明の一実施例を示す制御回路図である。１……交流電源、２……電源スイツチ、３……
CR積分回路、７……定電圧回路、１２……比較
器（PUT）、１６……引算回路（ブリツジダイオ
ード）。 FIG. 1 is a CR timer circuit showing a conventional example, FIG. 2 is a characteristic diagram showing the relationship between power supply voltage and time limit, and FIG. 3 is a control circuit diagram showing an embodiment of the present invention. 1... AC power supply, 2... Power switch, 3...
CR integration circuit, 7... constant voltage circuit, 12... comparator (PUT), 16... subtraction circuit (bridge diode).

Claims

[Claims]

1 A heater connected to an AC power supply via a switch, a CR integral circuit supplied with power by the closing operation of the switch, and a CR integral circuit that generates a voltage proportional to the voltage of the power supply, and converts this voltage into a constant voltage of a constant voltage circuit. a subtraction circuit that outputs the voltage subtracted from the output;
a comparator that compares the charging voltage of the charging capacitor in the CR integration circuit with the output of the subtraction circuit; A control circuit for a heating device that opens the switch when .