JPH1026901A - Temperature controller for thermal fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature controller for a thermal fixing device capable of obtaining stable fixing performance even when fixing environment is fluctuated, saving power and prolonging the life of a heating roller because excessive heating is avoided, and restraining the rise of cost. SOLUTION: The thermal fixing device has a heating rotating body 1 in which a heating source 2 is incorporated and is provided with a temperature detection means 3 for controlling the surface temperature of the rotating body 1, and the device is equipped with an initial temperature measuring means 4 measuring the initial temperature of the surface of the rotating body 1 shown before power is supplied to the heating source 2 of the rotating body 1 and the temperature rises through the detection means 3, a control temperature setting means 5 variably setting control temperature being the target temperature of the surface of the rotating body 1 in accordance with the initial temperature measured by the measuring means 4, and a heating source control means 6 controlling the heating source 2 with the control temperature set by the setting means 5 as the target temperature while comparing the target temperature with detected temperature from the detection means 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for a heat fixing device used in an image forming apparatus such as an electrophotographic copying machine and a printer.

[0002]

2. Description of the Related Art Conventionally, in a heat fixing device used in this type of image forming apparatus, a main power supply for operating the image forming apparatus is turned on, and at the same time, a power supply of the heat fixing apparatus is also turned on. The surface temperature of the heating roller of the heat fixing device is set to a specific control temperature regardless of the external environmental temperature, and the surface temperature of the heating roller is measured based on the control temperature. Is controlled by one temperature sensor.

However, the control temperature of the surface of the heating roller depends on the temperature of the image support such as paper and film before heat fixing, that is, the environmental temperature outside the fixing device. In general, the temperature is set to a higher temperature than an appropriate control temperature (normal control temperature) under a normal environment so that a good fixing performance can be obtained even under a low temperature, and the surface temperature of the heating roller is controlled by the high control temperature. ing.

For this reason, in a thermal fixing device controlled using one temperature sensor, even if the environmental temperature fluctuates, the surface temperature of the heating roller is controlled at a relatively high control temperature that is fixed. Therefore, there arises a problem of power consumption and a reduction in the life of the heating roller.

Therefore, conventionally, in order to solve this problem, a first measuring means for measuring a fixing environment condition (environmental temperature) is provided separately from a second measuring means for measuring the surface temperature of the heating roller. There has been proposed a temperature control means for changing the control temperature based on the measurement result (environmental temperature) by the first measurement means (Japanese Patent Laid-Open No. 5-66693). According to this method, the problem caused by setting the control temperature to a temperature higher than the normal control temperature is solved, but another measuring means must be additionally employed to measure the fixing environment conditions. However, this leads to an increase in the cost of the heat fixing device, and in fact, there is a problem that it is difficult to easily adopt it.

[0006]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a stable fixing performance even when the fixing environment fluctuates, to save electric power without excessive heating, and to extend the life of a heating roller. It is an object of the present invention to provide a temperature control device of a heat fixing device which can be easily adopted, can suppress cost increase, and can be easily adopted.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A temperature control device of a heat fixing device according to the present invention will be described with reference to the accompanying drawings. Basically, a heating rotator (1) having a built-in heating source (2) is provided. Then, in the heat fixing device provided with the temperature detecting means (3) for controlling the surface temperature of the heating rotator (1), the temperature detecting means (3) supplies the heating source (2) of the heating rotator (1). Initial temperature measuring means (4) for measuring the initial temperature of the surface of the heating rotator (1) before power-on and rising, and according to the initial temperature measured by the initial temperature measuring means (4). Control temperature setting means (5) for variably setting a target control temperature on the surface of the heating rotator (1); and a control temperature set by the control temperature setting means (5) as a target temperature. The heating source is compared with the temperature detected by the temperature detecting means (3). 2) it is a temperature control device for a thermal fixing apparatus having a heating source control means for controlling (6).

Further, according to the present invention, in the temperature control device of such a thermal fixing device, the initial temperature measured by the initial temperature measuring means (4) is equal to the upper limit value (TEH) of the allowable operating environment temperature.
Under the above conditions, the temperature control device of the thermal fixing device sets the target control temperature by the control temperature setting means (5) to the control temperature (TCL) corresponding to the upper limit value (TEH) of the allowable operating environment temperature. is there.

As a heat fixing device to which the present invention is applied,
Typically, the heating rotator (1) includes a heating roller having a built-in heating source, and a heating roller provided with a pressure roller which presses the heating roller under a predetermined pressure. The pressure roller also has a built-in heating source. The pressure roller also has a heating rotator (1) whose surface temperature is controlled, or a heating rotator (1) instead of the pressure roller. Pressing belt with pressure on heating roller, etc.
Various types can be mentioned.

In the present invention, as the temperature detecting means (3) used for controlling the surface temperature of the heating rotator (1), specifically, the temperature detecting means (3) is brought into contact with the surface of the heating rotator (1). A contact-type temperature sensor for detecting temperature, a non-contact temperature sensor using infrared rays, and the like can be given, and any of them can be suitably used.

In the present invention, the initial temperature measuring means (4) for measuring the initial temperature of the surface of the heating rotator (1) using the temperature detecting means (3) may be, for example, a main power supply of an image forming apparatus. Means for detecting that power has been applied to the heating source (2) of the heating rotator (1) and outputting a detected temperature signal from a temperature detecting means (3); When the main power is continuously supplied but the power of the heating source (2) of the heating rotator (1) of the heat fixing device is turned off, the heating rotator (1) is again turned on.
Means for detecting that the power of the heating source (2) is turned on and outputting a detected temperature signal from the temperature detecting means (3).

Further, the control temperature setting means (5) variably sets a target control temperature on the surface of the heating rotating body (1) according to the initial temperature measured by the initial temperature measuring means (4). The fixing temperature (strength) is determined by the toner temperature and the toner / paper contact area when passing through the nip (contact heating area) within the allowable operating temperature range specified for the image forming apparatus. If the measured initial temperature is low, the control temperature tends to be relatively high.If the measured initial temperature is high, the control temperature tends to be a relatively low control temperature. In consideration of this, the temperature is determined so as to control the temperature at which all the sheets can be fixed.

Here, with respect to the setting of the control temperature based on the measured initial temperature, preferably, the initial temperature measured by the initial temperature measuring means (4) is equal to or higher than the upper limit value (TEH) of the allowable operating environment temperature. Under the conditions, it is preferable that the target control temperature is set to the control temperature (TCL) corresponding to the upper limit value (TEH) of the operation allowable environmental temperature, thereby providing an advantage that the minimum fixing temperature (strength) is guaranteed. .

In the case where the heat fixing device to which the present invention is applied has a built-in heating source also on the pressure roller side and its surface temperature is measured and controlled by the temperature detecting means (3), The initial temperature on the pressure roller side is also measured together with the initial temperature on the heating roller side, and these are compared, and the lower initial temperature is used, and the heating roller and / or the heating rotator (1) are used. The target control temperature of the surface of the pressure roller may be variably set. By variably setting the target control temperature on the surface of the heating rotator (1) using the initial temperature not only on the heating roller side but also on the pressing roller side, the effect of correcting variations in sensor performance due to manufacturing can be obtained. Can be demonstrated.

In the present invention, the control temperature set by the control temperature setting means (5) as described above is set as a target temperature, and the target temperature is compared with the temperature detected by the temperature detection means (3). The source control means (6) controls the heating source (2), thereby controlling the surface temperature of the heating rotator (1). For this reason, it is not necessary to unnecessarily set the control temperature of the surface of the heating rotator (1) higher than the normal control temperature without providing any special temperature detecting means for measuring the environmental temperature of the heat fixing device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below based on embodiments shown in the accompanying drawings.

FIG. 2 shows a heat fixing device according to an embodiment of the present invention. This heat fixing device has a built-in heating source (2) and a contact type temperature sensor for controlling the surface temperature of the surface. A heating roller (1a) which is a full-color heat fixing roller provided with (3a); and a pressure roller (7) which comes into pressure contact with the heating roller (1a) and is rotated by rotation of the heating roller (1a). And a release oil supply device (8) for supplying release oil to the surface of the heating roller (1a).

The heating roller (1a) has a thickness of 1.1 m.
m iron roller core (9) is coated with a 1.5 mm thick highly thermally conductive silicone rubber layer (10), and its surface is further coated with a fluoro rubber layer (not shown) with a thickness of 30 μm. ing. The pressure roller (7) has a structure in which the temperature sensor (3a) and the fluoro rubber layer are removed from the heating roller (1a).
6 mm.

The contact pressure and the contact width between the heating roller (1a) and the pressure roller (7) are each 3 kg.
/ Cm ² and 4.5 mm, and the unfixed toner image (1
The moving speed of the sheet (support: 12) supporting 1) is 80
mm / sec. It is. The release oil supply device (8) supplies about 5 μl of amine oil as release oil per A4 size sheet.

The temperature of the contact type temperature sensor (3a) provided on the surface of the heating roller (1a) is 10
A thermistor exhibiting a characteristic of 200 to 2 kΩ at ~ 150 ° C is used.

Here, the temperature control device of the thermal fixing device according to the present embodiment will be described with reference to FIGS. 1, 3 and 4. The temperature control device according to this embodiment embodies the functions of the initial temperature measurement means (4), the control temperature setting means (5), and the heating source control means (6) of the present invention shown in FIG. For example, a temperature control algorithm according to a flowchart shown in FIG. 4 is implemented. First,
In accordance with the characteristics of the heat fixing device, as shown in FIG. The relationship between the optimum control temperature (TC) and the relationship between the initial temperature (TE) and the control temperature (TC) is stored in the control temperature setting means (5).

Therefore, when the main power supply (M / C power supply) of the image forming apparatus equipped with the heat fixing device is turned on, the power supply is also turned on to the heating source (2) of the heating roller (1a) at the same time, and the initial temperature measurement is performed. The means detects that power is supplied to the heating source (2) and outputs a detected temperature signal from the contact temperature sensor (3a) to the control temperature setting means (5).

In the control temperature setting means (5), the initial temperature (TE) and the control temperature (TC) are determined according to the initial temperature (TE) based on the detected temperature signal input from the initial temperature measuring means (4). , The optimum control temperature (TC) is determined, and this optimum control temperature (TC) is set as the control temperature in the heating source control means (6).

The heating source control means (6) sets the optimum control temperature (TC) set in this way as a target temperature of the surface of the heating roller (1a), and detects the temperature from the contact type temperature sensor (3a). The heating source (2) is controlled while comparing with the temperature, and the surface temperature of the heating roller (1a) is controlled to a target temperature, that is, a temperature close to an optimum control temperature (TC).

In the thermal fixing device of this embodiment, the minimum allowable operating temperature (TEL) and the maximum allowable operating temperature (TEH) are 10 ° C. and 30 ° C., respectively, and the optimum control temperature (TCH) and (TCL) is 138 ° C
And 128 ° C. Then, in a fixing test actually performed using a toner whose main polymer is polyester,
About 10% saving in power consumption was confirmed,
The release life of the heating roller (1a), which is a full-color heat fixing roller, was extended from the conventional 20,000 sheets to 50,000 sheets for the entire solid image (Y, M, C, and K toners).
In this embodiment, when the initial temperature (TE) of the heating roller (1a) is equal to or higher than the maximum allowable operating temperature (TEH), the control temperature (TC) is set to a constant value (TCL). Below, after using the image forming apparatus, the paper (12) supporting the unfixed toner image (11) was maintained at a high temperature due to a rise in temperature inside the apparatus, so that no major problem occurred.

The temperature control device according to the present invention includes a heat fixing device on which a heating roller (1a) and a pressure belt (13) are mounted as shown in FIG. 5, and a heat source (see FIG. 6). 2) and a heat fixing device equipped with a pressure roller (1b) having a contact-type temperature sensor (3b) can be applied in the same manner as in the above embodiment.

[0027]

According to the present invention, since the initial temperature of the heating rotator close to the ambient temperature is measured and the control temperature for controlling the surface temperature of the heating rotator is set based on this initial temperature, the fixing is performed. Even if the environment fluctuates, stable fixing performance can be obtained, and power can be saved and the life of the heating roller can be extended without excessive heating. Since a temperature sensor or the like is not used, an increase in cost can be suppressed, and it can be easily adopted in an actual machine.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a temperature control device of a heat fixing device according to the present invention.

FIG. 2 is an explanatory diagram showing one embodiment of a thermal fixing device equipped with a temperature control device of the present invention.

FIG. 3 shows an initial temperature (T) used in the heat fixing device of FIG. 2;
It is a graph which shows the relationship between E) and control temperature (TC).

FIG. 4 is a flowchart illustrating a fixing temperature control process performed by a temperature control device used in the thermal fixing device of FIG. 2;

FIG. 5 is an explanatory diagram showing a heat fixing device according to another embodiment in which the temperature control device of the present invention is mounted.

FIG. 6 is an explanatory diagram showing a heat fixing device according to still another embodiment in which the temperature control device of the present invention is mounted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating rotary body, 1a ... Heating roller, 1b ... Pressure roller, 2 ... Heating source, 3 ... Temperature detecting means, 3a, 3b ... Contact temperature sensor, 4 ... Initial temperature measuring means, 5 ... Control temperature setting means , 6 ... heating source control means, 7 ... pressure roller, 8 ...
Release oil supply device, 9: iron roller core, 10: high thermal conductive silicon rubber layer, 11: unfixed toner image, 12: paper (support), 13: pressure belt

Claims (2)

[Claims] 1. A heat fixing device having a heating rotator (1) in which a heating source (2) is built-in and a temperature detecting means (3) for controlling the surface temperature of the heating rotator (1). An initial temperature measuring means for measuring an initial temperature of the surface of the heating rotator (1) before power is applied to the heating source (2) of the heating rotator (1) by the temperature detecting means (3) and the heating source (2) rises; 4) a control temperature setting means (5) for variably setting a target control temperature of the surface of the heating rotator (1) according to the initial temperature measured by the initial temperature measuring means (4); The control temperature set by the temperature setting means (5) is set as a target temperature, and the target temperature and the temperature detection means (3) are set.
And a heating source control means (6) for controlling the heating source (2) while comparing the detected temperature with the temperature detected by the heating device. 2. The control temperature setting means (5) according to claim 1, wherein the control temperature setting means (5) determines that the initial temperature measured by the initial temperature measuring means (4) is equal to or higher than an upper limit value (TEH) of an operation allowable environmental temperature. A temperature control device for a thermal fixing device, wherein a target control temperature is set to a control temperature (TCL) corresponding to an upper limit value (TEH) of an operation allowable environmental temperature under a certain condition.