JPH0473675A - Temperature controller - Google Patents

Abstract

PURPOSE:To optimally control the temperature of a heated object by switching a temperature controlled according to whether it is action time or standby time to a 1st control target temperature(temperature for action) or a 2nd control target temperature(temperature for standby) after optimally controlling the temperature of the heated object to the temperature for action once. CONSTITUTION:The temperature is controlled to the temperature for action Tc once by considering the thermal time constant of a heating roll 1 and a heater 1a and the characteristic of a temperature sensor 5, etc., when a thermal fixing device starts up from an action stop state. Therefore, for example, even when the action is instructed immediately after the start-up, the actual temperature of the roll 1 is prevented from excessively rising. Then, according to whether or not the action is instructed, constant temperature control in which the temperature for action Tc is taken as a reference temperature or constant temperature control in which the temperature for standby Ts is taken as a reference temperature is performed so as to control the device in an action state or a standby state, thereby obtaining a necessary condition. Whenever the action may be instructed, the roll 1 and the heater 1a are protected and the malfunction of a temperature excessive rising preventing device 3 is prevented.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention detects the temperature of an object to be heated and controls the temperature to drive a heating element that heats the object to be heated in accordance with the detected temperature. Regarding a control device.

(Prior Art) In an electrophotographic recording device such as a laser printer, one of the fixing devices that fixes the toner transferred to the recording paper onto the recording paper.
There is a heat roll. This heat roll is a roller heated by a heater or the like that melts the toner adhering to the recording paper, and another roller that is placed opposite to the above roller and clamps the recording paper to spread the melted toner onto the recording paper. Crimp.

In such a heat roll, it is necessary to keep the temperature of the roller constant in order to obtain a stable image and ensure safety. For this reason, the temperature of the rollers is controlled, and this is usually done by thermal feedback.

FIG. 5 is a block diagram showing an example of the configuration of a conventional temperature control device applied to the above-described heat fixing device. In the figure, 1 is a heat roll of a heat fixing device, and a heater 1a is provided inside. The heater 1a is energized and heated by a power source 4 via a switch 2 and an overtemperature rise preventer 3 such as a fuse or a thermostat. On the other hand, the temperature sensor 5 detects the temperature of the heat roll 1 and provides the A/D converter 6 with a signal having a voltage value corresponding to the detected temperature. A
The /D converter 6 converts the input signal into digital data and provides it to the control section 7. If the detected temperature indicated by the input digital data is lower than a predetermined temperature (hereinafter referred to as the control target temperature), the control unit 7 turns on the switch 2 to heat the heater 1a with electricity, and if the detected temperature is lower than the control target temperature. If it is higher than the temperature, switch 2 is turned off and heater 1a is turned off.
Stop energizing heating.

By the way, in a heat fixing device to which the above-described temperature control device is applied, the temperature of the heat roll 1 of the heat fixing device is controlled to a lower temperature than usual in order to reduce power consumption when no recording is being performed. do. That is, two types of control target temperatures are set: an operating temperature during normal operation and a standby temperature lower than this operating temperature, and these two types of control target temperatures are switched depending on the operating/standby state.

When performing two-stage control of operating temperature and standby temperature in this way, conventionally the control is aimed at the standby temperature at startup, and then the operating temperature is adjusted once an operation instruction has been issued. This will lead to a transition to the desired control.

Figure 6 shows the heat roll 1 when performing the above control.
It is a figure showing an example of temperature change. In the figure, A1 indicates the change in detected temperature during normal control. In this way, under normal conditions, control is performed aiming at the standby temperature Ts at startup, and thereafter, control is performed aiming at the operating temperature Tc from when an operation instruction is given (point A in the figure). .

At this time, when starting up from the stopped state, the temperature sensor 5 cannot fully follow the temperature rise of the heat roll 1.
The detected temperature ends up being lower than the actual temperature of the heat roll 1. In other words, what is indicated by B1 in FIG. 6 is the change in the actual temperature of the heat roll 1 during normal control, which is higher than the detected temperature (the actual temperature of the heat roll 1 is the highest). The difference in time is T in Figure 6.
e). Furthermore, due to the influence of the thermal time constants of the heat roll 1 and the heater 1a, a so-called overshoot (To in Fig. 6) occurs in which the temperature of the heat roll 1 continues to rise for a while after the heater 1a is de-energized. . Therefore, the actual temperature of the heat roll 1 exceeds the standby temperature Ts by the temperature (Te+To) shown by Tx in FIG. 6, but this causes the temperature of the heat roll 1 to greatly exceed the operating temperature Tc. Nothing like that happens and there is no problem. and,
By continuing control based on standby temperature Ts,
The actual temperature of the heat roll 1 and the detected temperature gradually converge and eventually follow each other.

Thus, in a state where the detected temperature follows the actual temperature of the heat roll 1, if an operation instruction is given at time A in FIG. 6, for example, the actual temperature of the heat roll 1 will be There is no large error between the temperature and the detected temperature, and the temperature can be controlled without excessive rise.

However, during a period when the actual temperature of the heat roll 1 and the detected temperature have not completely converged, for example, when an operation instruction is given at the time point in FIG. 6, the control is performed at a detected temperature lower than the temperature of the heat roll 1. As a result, the temperature of the heat roll 1 rises significantly as shown by TV in FIG. In FIG. 6, A2 indicates a change in the detected temperature at this time, and B2 indicates a change in the actual temperature of the heat roller 1.

In this way, when the temperature of the heat roll 1 exceeds the operating temperature Tc, the life of the heat roll 1 and the heater 1a may be shortened,
There is a risk that the overtemperature rise preventer 3 may malfunction.

(Problems to be Solved by the Invention) As described above, in the conventional temperature control device, the temperature sensor does not yet follow the temperature rise of the heated object when it is controlled at the standby temperature at startup. In this state, when an operation instruction is issued, the actual temperature of the object to be heated temporarily rises excessively. For this reason, there have been problems such as shortening the lifespan of the object to be heated and the heating element, and causing the overtemperature rise preventer to malfunction.

The present invention was made in consideration of these circumstances, and its purpose is to optimally control the temperature of the object to be heated without causing an excessive rise in temperature even during startup. An object of the present invention is to provide a temperature control device.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a method for detecting a temperature detected by a temperature detection means such as a temperature sensor and a first control target temperature (operating temperature) at the time of temperature startup.
a first control means for controlling energization of a heating element such as a heater based on the detected temperature and a predetermined preliminary control temperature lower than the detected temperature; a second control means for controlling energization of the heating element based on the detected temperature and the first control target temperature after a predetermined time has elapsed from the time when the temperature reaches the preliminary control temperature; After the detected temperature reaches the first control target temperature at least once by the control of the control means, the detected temperature and the The energization of the heating element is controlled based on the first control target temperature, and when in standby, the energization of the heating element is controlled based on the detected temperature and the second control target temperature (standby temperature). and third control means.

(Function) By taking such measures, when the temperature is started up, the temperature detected by the temperature detection means such as a temperature sensor reaches the preliminary control temperature until a predetermined period of time has elapsed. The energization of a heating element such as a heater is controlled based on the detected temperature and a predetermined preliminary control temperature lower than the first control target temperature (operating temperature). Thereafter, energization of the heating element is controlled based on the detected temperature and the first control target temperature until the detected temperature reaches the first control target temperature by at least one degree. Furthermore, after this, depending on whether the mode is operating or standby, the detected temperature and the first temperature are adjusted when operating.
The energization control of the heating element based on the control target temperature of
Further, during standby, energization of the heating element is controlled based on the detected temperature and the second control target temperature (standby temperature).

Therefore, once the temperature of the heated object is optimally controlled to the operating temperature, the temperature to be controlled will be set to the first control target temperature (operating temperature) or the second control target temperature (operating temperature) depending on whether it is during operation or standby. The temperature is switched to the control target temperature (standby temperature).

(Embodiment) Hereinafter, a temperature control device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration when the present temperature control device is applied to a heat fixing device. Note that the same parts as in FIG. 5 are given the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, reference numeral 11 denotes a control unit that monitors digital data provided from the A/D converter 6 and controls 0N10FF of the switch 2. This control section 11 has, for example, a microcomputer as a main control circuit, and has a first
Control means 11a, second control means 11b1, third control means 1
1c.

Next, the operation of the temperature control device configured as described above will be explained according to the processing procedure of the control section 11.

First, when the control section 11 receives an instruction to raise the temperature of the heat roll 1 from the outside (for example, when the power is turned on), as shown in FIG. Detected temperature Tx based on the detected temperature Tx
Determine. The detected temperature here is the start-up temperature. Next, in step b, a preliminary control temperature Tw is set according to the detected temperature Tx. The reason why the preliminary control temperature Tw is set according to the start-up temperature is because the difference between the actual temperature of the heat roll 1 and the detected temperature and the amount of overshoot occur depending on the start-up temperature. , the preliminary control temperature Tw is determined by measurement or the like based on these, and is set in the control section 11 in advance.

Subsequently, in step C, the control unit 11 turns on the switch 2 to energize the heater 1a.

As a result, the temperature of the heat roll 1 rises as shown in FIG. In this state, the control unit 11 waits for the detected temperature Tx to reach the preliminary control temperature Tw in steps d and e as shown in FIG. 2, and when the detected temperature Tx reaches the preliminary control temperature Tw (see FIG. At the middle point c), the control unit 11 shifts the process from step e to step f. In step f, the control unit 11 turns the switch 2 to
After stopping the power supply to the heater 1a as an FF, in step g, constant temperature control is performed using the preliminary control temperature W as a reference temperature.

FIG. 3 is a flowchart showing 11 control procedures for constant temperature control. As shown in this figure, in constant temperature control, the control section 1 first determines the detected temperature Tx based on the output signal of the A/D converter 11 in step r. Subsequently, in step S, the control unit 11 determines whether the detected temperature determined in step r is equal to or higher than the reference temperature (here, the preliminary control temperature Tw), and if the detected temperature Tx is equal to or higher than the reference temperature, the control unit 11 performs step S. At step t, the switch 2 is turned off, and if the detected temperature Tx is lower than the reference temperature, the switch 2 is turned on at step U.

After completing the constant temperature control as described above, the control section 11 controls the second temperature control.
In step h in the figure, in step e the detected temperature Tx
Whether a predetermined time 1+ (preset according to the characteristics of the heat roll 1 and the heater 1a) has elapsed from the time when it is determined that the temperature has reached the preliminary control temperature Tw (time c in FIG. 4). This predetermined time period 1. The processes from step f to step h are repeated until the time period elapses. As a result, constant temperature control based on the preliminary control temperature Tw is repeatedly performed. While performing constant temperature control based on this preliminary control temperature Tw, the temperature Tx detected by the temperature sensor 5 gradually follows the actual temperature of the heat roll 1, and the error in the temperature detected by the temperature sensor 5 increases. Decrease. The processing up to this point is performed by the first control means 11a.

Then, when a predetermined time t has elapsed, at point 2) in FIG. 4, the control section 11 shifts the process from step h to step i. The control unit 11 turns the switch 2 to O in this step j.
NL, restart the energization of the heater 1a. Thereafter, in steps j and k, the control unit 11 waits for the detected temperature Tx to reach the operating temperature Tc, and when the detected temperature Tx reaches the operating temperature Tc (time point 5 in FIG. 4), the process proceeds to step Move from step k to step g. In step g, the control unit 11 turns off the switch 2 to stop energizing the heater 1a, and then in step m, performs constant temperature control using the operating temperature Tc as the reference temperature according to the procedure shown in the third figure.

After the constant temperature control as described above is completed, in step n, the control unit 11 controls the temperature for a predetermined time tz from the time when it is determined in step that the detected temperature Tx has reached the operating temperature Tc (time HO in FIG. 4). It is determined whether or not (an arbitrary time) has elapsed, and the processes of step m and step n are repeated until the predetermined time t2 has elapsed. Thus,
Regardless of whether the heat fixing device is in operation or standby, the temperature of the heat roll 1 is temporarily controlled to the operating temperature Tc. The processing of steps i to n is performed by the second control means 11b.

Then, when the predetermined time t2 has elapsed (to the point in time in FIG. 4), the control section 11 shifts the process from step n to step 0. In step 0, the control unit] determines whether or not an action instruction has been given, for example, by referring to an action instruction flag. Here, if no operation instruction has been given, the control unit 11 moves the process from step 0 to step p, and in step p, performs constant temperature control using the standby temperature Ts as the reference temperature according to the procedure shown in the third diagram. .

As a result, the heat fixing device enters a standby state. Further, if an operation instruction has been given in step 0, the control unit 11 moves the process from step 0 to step q, and this step q
In this step, constant temperature control is performed using the operating temperature Tc as a reference temperature according to the procedure shown in the third diagram.

As a result, the heat fixing device becomes operational. After the constant temperature control in step p or step q is completed, the control unit 11 repeats the process of moving to step 0. The processing from step 0 to step q is performed by the third control means 11c.

Thus, according to this embodiment, when the heat fixing device is started up from a stopped state, the heat roll 1 and the heater 1a are
Since the operating temperature is once controlled to Tc after taking into account the thermal time constant of It never rises. After this, depending on whether an operation instruction is given or not, constant temperature control with the operating temperature Tc as the reference temperature or standby temperature T
A constant temperature control is performed using s as a reference temperature, and the device is controlled to be in an operating state or a standby state, and a necessary state is obtained.

In this way, no matter at what point the operation instruction is given, the actual temperature of the heat roll 1 can be prevented from rising excessively, the heat roll 1 and the heater 1a can be protected, and the temperature overrise preventer 3 can be prevented from malfunctioning. can also be prevented.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the preliminary control temperature Tw is changed and set based on the startup temperature, but the preliminary control temperature Tw may be set to a fixed value.

Further, in the above embodiment, a temperature control device that controls the temperature of a heat fixing device is shown, but the temperature control device of the present invention can be applied to any heat generating device that needs to control the heat generation temperature to a constant temperature. . Further, in the above embodiments, temperature control processing is performed by software by a microcomputer, but it may be performed by a hardware circuit. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, at the time of temperature startup, the temperature detected by the temperature detection means such as a temperature sensor, the predetermined preliminary control temperature lower than the first control target temperature (operating temperature), and the detected temperature a first control means for controlling energization of a heat generating element such as a heater based on the above; after the elapsed time, a second control means controls the energization of the heating element based on the detected temperature and the first control target temperature; After reaching the control target temperature at least once, depending on whether the temperature is in operation or in standby, the heating element is heated based on the detected temperature and the first control target temperature when in operation. and a third control means that controls the energization of the heating element based on the detected temperature and the second control target temperature (standby temperature) when the heating element is on standby. This provides a temperature control device that can optimally control the temperature of the object to be heated without causing an excessive rise in temperature even during startup.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining a temperature control device according to an embodiment of the present invention, in which FIG. 1 is a block diagram showing the configuration, and FIGS. 2 and 3 are diagrams for explaining the temperature control device in FIG. FIG. 4 is a flowchart showing the processing procedure of the unit 11, FIG. 4 is a diagram showing an example of changes in the temperature of the heat roll 1 and the detected temperature Tx, and FIGS. 5 and 6 are diagrams each explaining the prior art. 1... Heat roll, la... Heater, 2... Switch, 3... Overtemperature rise preventer, 4... Power supply, 5
...Temperature sensor, 6...A/D converter, 11...Control unit, 11a...First control means, llb...Second control means, C...Third control means.

Claims (1)

[Claims] The temperature of the object to be heated heated by the heating element is set at a predetermined first control target temperature during operation, and at the first control target temperature during standby, based on the temperature detected by the temperature detection means. In a temperature control device that controls to a predetermined second control target temperature that is lower than the detected temperature, when the temperature is started up, the detected temperature is set to a predetermined preliminary control temperature that is lower than the first control target temperature and the detected temperature. a first control means for controlling the energization of the heating element based on the first control means; and after a predetermined time has elapsed from the time when the detected temperature reaches the preliminary control temperature by the energization control of the heating element by the first control means. , a second control means for controlling energization of the heating element based on the detected temperature and the first control target temperature, and the detected temperature is controlled to be the first control target by the control of the second control means. After the temperature reaches at least one degree, depending on whether it is in operation or standby, when it is in operation, energization control of the heating element is performed based on the detected temperature and the first control target temperature. and a third control means that controls energization of the heating element based on the detected temperature and the second control target temperature when the temperature control device is on standby.