JPS63166180A - Electric hot plate controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for use in household electric hotplates.

BACKGROUND OF THE INVENTION In general, this type of electric plate is equipped with two heaters 1 and 2 as shown in FIG. I'm trying to heat up some parts. The heaters 1 and 2 can be switched by a changeover switch 3, and a bimetal thermostat 4 is installed in the common energizing circuit to control the temperature of the plate by mechanically opening and closing contacts. was.

Problems to be Solved by the Invention In the conventional configuration, the bimetal thermostat 4 controls the common temperature of the two heaters 1 and 2.
Although the control temperature range is wide, there is a problem in that it is difficult to control the temperature accurately because the amount of change in the bimetal is small.

Further, the bimetal thermometer 4 has two heaters 1.2.
The capacitance must be large enough to withstand the large current when both are closed due to a failure or the like, which is disadvantageous in terms of cost. Furthermore, the changeover switch 3 is manually operated, and the present invention takes into account these conventional problems and enables efficient temperature control without increasing the capacity of the temperature control switch. The present invention aims to provide a control device for an electric hot plate that can be operated with a soft touch.

Means for Solving the Problems The present invention has been made to eliminate the above-mentioned drawbacks of the conventional technology. A switch for changing the settings of the control circuit, a plurality of relays actuated by the output of the temperature control circuit, a selection circuit for the relays, and a switch for changing the settings for the selection circuit. , a control device is connected to each heater individually.

Function: In the temperature control device for an electric hot plate having the above configuration, the temperature control circuit operates based on the output voltage of the temperature sensor, and drives the relay to control the opening and closing of the relay contacts connected to the heater. The settings of the temperature control circuit are changed in advance by a change switch to perform accurate control, and which of the relays is energized first is selected by a selection circuit set by the change switch. Become.

EXAMPLES Hereinafter, examples of the present invention will be explained with reference to the drawings. In the figure, numerals 3 and 4 are heaters embedded in the plate, and a relay switch 5.6 is inserted into the energizing circuit thereof. The relay switch 6.6 is controlled by relay coils 9, 1o, and the relay coils 9, 10 are each driven by a transistor 7.8.

The transistor 7.8 is controlled by a NAND circuit 11.12, and a signal from a flip 70 knob 13, which is the main component of the relay selection circuit 23, is supplied to the NAND circuit 11.12. . The input switch 14 of the flip-flop 13 determines which of the heaters 3 and 4 is energized.

Reference numeral 16 denotes a heat-sensitive resistance element constituting a temperature sensor, which is in contact with the bottom surface of the plate, and whose signal is given to the voltage comparator 16 of the temperature control circuit 24.
The outputs of are given to the NAND circuits 11 and 12.

A plurality of reference resistors 17 are connected to the reference voltage terminal of the comparator 16.
~2o is connected, and the reference resistance 1 is connected to the counter circuit 2.
The temperature is set depending on which resistor from 7 to 20 is used. The counter circuit 21 is driven by a switch 22, which is operated to change the temperature.

In the above configuration, when the power is connected now, the initial state of the 7-lip flop 13 is set so that the E terminal is High, and therefore the output of the NAND circuit 11 becomes Low, so the transistor 7 is turned on and the coil 9 is turned on. When driven, the relay switch 6 closes and the heater 3 is energized.

When the switch 22 is operated, the output of the counter circuit 21 sequentially changes from A to High, so that the reference resistor 17
The heat sensitive resistance element 16 until the reference voltage determined by ~20 is reached.
When the value changes, the output of the voltage comparator 16 becomes Low, and the output of the NAND circuit 11 becomes High, so the transistor 7 is turned off, and therefore the relay switch 6 is opened and the power supply to the heater 4 is stopped.

When the switch 14 is operated to set the F terminal of the flip-flop 13 to High and the E terminal to Low, the output of the NAND circuit 12 becomes Low, and the output of the other NAND circuit 11 becomes Low.
The output of becomes High. Therefore, transistor 8 is turned on, relay switch 6 is closed, and heater 3 is energized.

As described above, it is possible to determine which heater is energized using the switches 14 and 22, and also to change the set temperature.

Note that both the switches 14 and 22 can be of low voltage and low current. In addition, NAND circuit 1 of this configuration
1, 12, the flip-flop 13, the counter circuit 21, etc. may be constructed on one chip using a microcomputer.

Effects of the Invention As is clear from the above description of the embodiments, in the present invention, a relay switch is individually connected to each heater, and the driving of the relay switch is precisely controlled by a temperature control circuit whose operation is set. Further, each relay switch is selected by a selection circuit, and it is determined which one to operate first, making it easy to use.

Furthermore, the temperature control circuit, selection circuit, drive circuit, etc. are electronic circuits, and the switches associated with these can be configured as small-capacity and touch-type, eliminating the need to use large-capacity bimetal thermostats and changeover switches as in the past. , the effect is great.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an electric hot plate showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of an electric hot plate showing a conventional example. 2.3...Heater, 5,6...Relay switch, 9.10...Relay coil, 23.
... Relay selection circuit, 16 ... Temperature sensor, 24 ... Temperature control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] An electric hot plate having a plurality of heaters installed on the plate, comprising a temperature sensor consisting of a heat-sensitive resistance element, a temperature control circuit operated by the output voltage of the temperature sensor, a switch for changing the settings of the temperature control circuit, and a temperature Control of an electric hot plate comprising a plurality of relays actuated by the output of a control circuit, a selection circuit for said relays, and a switch for changing the setting of said selection circuit, the contacts of each relay being individually connected to each of said heaters. Device.