JPS60229123A - Temperature controller - Google Patents

Abstract

PURPOSE:To control quickly and accurately the temperature to a set level by detecting a temperature range which includes a temperature to be detected among plural temperature ranges and controlling the electric power supplied to a heater by those temperature ranges. CONSTITUTION:A light-up ratio control circuit 3 detects an range including the temperature of a heater 1 by the output fed from FF9a-9e. In other words, it is detected that a certain prescribed range includes the temperature of the heater 1 when the outputs of FF9b, 9d and 9a are set at L levels with the outputs of FF9e and 9c set at H level respectively. The circuit 3 controls the light-up ratio according to each area. That is, a prescribed level is decided when the temperature of the heater 1 exists in a certain corresponding area. While an extremely high or low temperature is decided when the temperature of the heater 1 exists in another range. Thus the supply of power is stopped to the heater 1. In such a way, the temperature of the heater 1 can kept at reference level (a), i.e., a set temperature. This can reduce the ripple of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a temperature control device that can accurately control the temperature of a controlled object.

Conventional technology Conventionally, the most commonly used temperature control device compares the temperature of a predetermined target to be controlled with the temperature of a heater, and if the temperature of the heater is lower, it supplies power to the heater. do. Furthermore, when the temperature of the heater is higher, the supply of electric power to the heater is stopped or reduced to suppress the rise in temperature of the heater.

Problems to be Solved by the Invention However, the above conventional techniques have the following problems. That is, since the heater i can only be controlled to turn ON or OFF with respect to the set temperature of the controlled object, it is very rough, and the overshoot with respect to the set temperature is large and unstable.

The present invention solves the above-mentioned problems and makes it possible to quickly and accurately control the set temperature.

Means for Solving the Problem The present invention, as a means for solving the problem, defines a plurality of reference temperatures in advance, and defines a plurality of temperature ranges using two adjacent reference temperatures among the plurality of reference temperatures. , it detects which temperature range of the plurality of temperature ranges the detected temperature falls in, and controls the electric power supplied to the heater according to the plurality of temperature ranges.

Effect: By using the above-mentioned means, the present invention controls the electric power supplied to the heater depending on the temperature range to which the controlled object belongs, and makes it possible to stably control the temperature to the set temperature.

EXAMPLE An example of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of a temperature control device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a heater, inside which a temperature detection element such as a thermistor is attached, and the output of the temperature control element is input to the input terminal (2) of the comparator 6. 2 is a power source that supplies power to the heater 1; 3 is a lighting control circuit that controls the power supplied to the heater 1; Here, the lighting ratio refers to the ratio of the operating time of the fixing device to the lighting time of the heater 1, and in this embodiment, five types of lighting ratios are used as shown in FIG. Note that the shaded area in FIG. 2 means that the heater is turned on. 4 is a pulse generator that generates clock pulses, and 6 is a decoder that sequentially selects one of the six output terminals to make it conductive according to the clock pulses output from the pulse generator 4. Note that the reason why there are six outputs from the decoder 5 is because six reference temperatures are set in this embodiment. The resistors 8a to 8f create a voltage level corresponding to the reference temperature based on the resistance value ratio with the resistor 7. That is, any one of the six reference temperatures is created by the ratio of the resistance values of the resistor 7 and the resistor 8f. Further, another reference temperature is created by the ratio of the resistance values of the resistor 7 and the resistor 8e, and other reference temperatures are created in the same manner.

Here, if the six reference temperatures are determined as shown in FIG. Therefore, as shown in FIG.
Six types of voltage levels corresponding to the six reference temperatures are sequentially illuminated on the terminals in a time-division manner. Comparator 6
compares the output signal of the temperature detection element provided in heater 1 and the voltage levels corresponding to the six reference temperatures in a time-sharing manner, and if the temperature of heater 1 is higher, Its output becomes No. 1, and the heater 1
When the temperature is lower, the level becomes low. 9a-9
All f are flip-flops (hereinafter referred to as FF), and as shown in FIG.
One FF among the FFs 9a to 9f becomes active. Further, a signal informing the comparison result from the comparator 6 is inputted to the FFs 9a to 9f, and the FFs in the active state operate based on the output from the comparator 6. Therefore, the FFs 9a to 9f sequentially become active and operate in response to a signal indicating the comparison result obtained from the comparator 6 in a time-division manner. 10, 11.12 are FF F9a and FF9. f
This is a counter that counts the number of clock pulses being output from the pulse generator 4 when the output from the pulse generator 4 is at a no-y level. 19, 20° 21 are the counters 10, respectively.
, 11. This is a memory that stores the contents of 12. 22.
23 is a determination circuit, which connects memories 19 and 2, respectively;
The output contents from the memory 19 and 20 are compared with the contents stored in advance in the determination circuits 22 and 23, and when the output contents of the memories 19 and 20 are smaller, the output signal is set to high level. Similarly, 24 is also a determination circuit, but the determination circuit 24 stores two types of contents in advance and outputs three types of determination results. 1aa and 13b are counters that are cleared at the falling edge of the input signal from the differentiating circuit 18 and count clock pulses from the pulse generator 4 during the period when the input signal is at a high level. 14 is an OR circuit, and 16, 16 and 17 are inverters. Further, 18 is a differentiation circuit that differentiates the output signal of the FF 9a.

The temperature control section configured as described above performs the temperature control described below.

That is, using reference temperatures a, b, c, d, and e, the fourth
As shown in the figure, there are 6 areas (41 ports).

C, 2, E, and F] are provided to detect in which region the temperature of the heater 1 exists, and to control the lighting ratio according to the region in which the temperature exists. Table 1 shows the area [A22RO, H2, E, H] and FF (9a.

9b, 9c, 9d, 9e).

Table 1 The lighting ratio control circuit 3 includes FFs [9a, 9b, 9c.

It is detected in which range the temperature of the heater 1 exists based on the outputs from the heaters 9d and 9e). That is, FF(9b,
9d, 9a] is L (o-level), and the FF
If the output of (9e, 9c) is H (high level),
It is detected that the temperature of heater 1 is present in area 2. This detection is performed by resistors 8a to 8I as shown in FIG.
This is done after all have been selected. When the lighting ratio control circuit 3 detects in which region the temperature of the heater 1 is present, it controls the lighting ratio according to each region as shown in FIG. In other words, if the temperature of heater 1 is in area C, the lighting ratio is 1/6, and if it is in area A or H, the temperature is abnormally high or low, so the lighting ratio is 1/6. Completely stop power supply.

Note that the lighting ratio for each area is not limited to the numerical values shown in FIG. 2, and may be arbitrarily determined. By performing the temperature control as described above, the temperature of the heater 1 can be maintained at the reference temperature a, which is the set temperature, and the temperature ripple (difference between the reference temperature a and the temperature of the heater 1) can be reduced. can.

Effects of the Invention As described above, according to the present invention, a plurality of reference temperatures are determined in advance, two adjacent reference temperatures are selected from the plurality of reference temperatures, and the temperature between the selected reference temperatures is Since the rate of temperature change of the heater is determined and the power supplied to the heater is controlled based on the determination result, initial overshoot and the like can be prevented and stable temperature control can be quickly performed with respect to the set temperature.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a temperature control device according to an embodiment of the present invention, Fig. 2 is a waveform diagram showing the lighting ratio, and Fig. 3 shows the relationship between the reference voltage applied to the O terminal of the comparator and time. figure,
FIG. 4 is a temperature characteristic diagram of the heater. 1... Heater, 2... Power supply, 3...
... Lighting ratio control circuit, 4 ... Pulse generator, 5 ... Decoder, 6 ... Comparator, 9
a~9f...Flip-flop, 10.11.
12.13a, 13b---Counter, 18・
...differentiation circuit, 19,20.11 ...memory, 22,23.24 ...determination circuit.

Claims (1)

[Claims] A plurality of reference temperatures are determined in advance, a plurality of temperature ranges are defined by two adjacent reference temperatures among the plurality of reference temperatures, and it is determined in which temperature range of the plurality of temperature ranges the detected temperature falls. A temperature control device that detects the temperature and controls power supplied to the heater according to the plurality of temperature ranges.