JPH05100755A - Controller for heating body and thermal fixing device - Google Patents

Abstract

PURPOSE:To supply the suitable power and to keep the temperature of a heating body or a thermal fixing device constant without setting beforehand the resistance value of an energizing exothermic body or without energizing temporarily at the time of starting the copying for a thermal image fixing device. CONSTITUTION:The devices are equipped with a detecting means 4 to detect the temperature of an energizing exothermic body 3 or a heating body 1 including it, a measuring means 13 to measure the hourly change rate of the temperature in the period when the energizing exothermic body 3 or the heating body 1 are set beforehand from the signal of the detecting means 4, and a power controller 12 to control the power supplied to the energizing exothermic body 3 based on the measured result of the measuring means 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric heating element or a heating element including the same, and a heat fixing device.

[0002]

2. Description of the Related Art Conventionally, for example, in an image heat fixing apparatus using a linear heater having a low heat capacity such as a ceramic heater,
In order to maintain the temperature of the heating element at a substantially constant level, the power supplied to the energizing heating element of the heating element is controlled by comparing the detected temperature with a preset temperature and supplying power according to the comparison result. Was changed (JP-A-2-259793). Further, in order to suppress the influence of variations in the resistance value of the heater (heating element), the heater resistance value is made to correspond to a preset resistance value range code, and the control group of the supplied power can be changed according to this code ( Japanese Patent Application 2-80
No. 16), the heating element is temporarily energized and the electric power is controlled according to the temperature rise (Japanese Patent Laid-Open No. 2-163787).

[0003]

However, in the above-mentioned conventional example, it is necessary to measure the heater resistance value and preset the code corresponding to the heater resistance value with a dip switch or the like. Alternatively, it is not suitable for application to an image forming apparatus that requires an instant start (quick start property) because it requires temporary energizing time.

Therefore, according to the present invention, with respect to an electric heating element or a heating element including the heating element, appropriate electric power is supplied to the heating element to set a predetermined temperature without setting a heater resistance value in advance or temporarily energizing the heating element. An object of the present invention is to provide a control device and a heat fixing device capable of maintaining and controlling the temperature substantially constant.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a detecting means for detecting the temperature of an electric heating element or a heating element including the electric heating element, and the electric heating element or the heating element is preset from the signal of the detecting means. And a power control device for controlling the power supplied to the energizing heating element based on the measurement result of the measuring means. It is a control device for the heating element.

Further, the present invention has a low heat capacity linear heating element, has detection means for detecting the temperature of the heating element, and within a preset period of the heating element from the signal of the detection means. And a power control device for controlling the power supplied to the heating element based on the measurement result of the measuring means, and a heat fixing device, Is.

[0007]

That is, the present invention measures the temperature change rate for a preset period after the start of energization of the heating element and changes the control group of the supplied power according to the measurement result.
Proper electric power can be supplied without setting the heater resistance value in advance or without temporarily energizing the image heating and fixing device at the start of copying, and keeps the temperature of the heating element or heat fixing device constant. I was able to do it.

[0008]

【Example】

<Embodiment 1> (FIGS. 1 to 5) In this embodiment, the present invention is applied to a film heating type image heat fixing device using a linear heater of low heat capacity.

(1) Schematic structure of the fixing device (FIG. 1) 5 is an endless belt-shaped fixing film, which is a driving roller 6 on the left side, a driven roller 7 on the right side, and a lower portion between the rollers 6 and 7. The low heat capacity linear heating element 1 as a heating element fixedly supported and disposed, and the guide roller 6a disposed below the drive roller 6, the four members 6 in parallel with each other.
Suspended between 7.1.6a.

The driven roller 7 also serves as a tension roller for the fixing film 5, and the fixing film 5 has a predetermined peripheral speed in the clockwise direction with the clockwise rotation of the driving roller 6 without wrinkling, meandering, or speed delay. It is driven to rotate.

Numeral 8 is a pressure roller having a rubber elastic layer such as silicone rubber having a good releasability as a pressure member, and is provided between the lower film portion of the endless belt-shaped fixing film 5 and the heating body 1. It is sandwiched between and is pressed against the lower surface of the heating element 1 by a biasing means (not shown) with a contact pressure of, for example, a total pressure of 4 to 7 kg, and a transfer material (not shown) from the image forming portion (A) ( The recording material) 9 is rotated counterclockwise in the forward direction in the conveying direction.

Since the endless belt-shaped fixing film 5 which is rotationally driven is repeatedly subjected to heat fixing of the toner image, it is excellent in heat resistance, releasability and durability, and is generally 1
A thin film having a thickness of 00 μm or less, preferably 40 μm or less is used. For example, polyimide, polyetherimide, P
A single-layer film of a heat-resistant resin such as ES / PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin) or a composite layer film, for example, PTFE of at least the image contact surface side of a heat-resistant film having a thickness of 20 μm
(Polytetrafluoroethylene resin) -Fluorocarbon resin such as PAF, and a releasable coating layer with a conductive material added to it.
For example, it is thickly applied.

The low heat capacity linear heating element 1 as a heating element is
In this example, the fixing film cross direction (fixing film 5
A heater substrate 2 which is long in the direction perpendicular to the running direction of the substrate and a heating element which is formed on the surface of the substrate 2 facing the fixing film 5 in a linear or strip shape along the length. And the temperature detection element 4 and the like provided on the heater substrate surface on the opposite side. 1A is a heater support that supports this heating element.

The heater support 1A is a member for supporting the heating element 1 in a heat insulating manner in a fixing device or an image forming apparatus, and for example, PPS (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether). Highly heat resistant resins such as ether ketone) and liquid crystal polymers, and composite materials of these resins and ceramics, metal, glass, etc.

The heater substrate 2 has heat resistance and electric insulation, and as an example, the thickness is 1.0 mm and the width is 10 m.
It is an alumina substrate with m and a length of 240 mm. Alternatively, it is a composite material substrate containing the same.

The heating element layer 3 is, for example, Ta along the longitudinal direction at a substantially central portion of the lower surface of the substrate 2 on the film sliding side.
₂ N · silver coating electrical resistance material such as palladium in the width 1.0 mm (screen printing) and a heat-generating layer of linear or strip-shaped low heat capacity is provided with, is energized from both longitudinal ends (Figure 2).

The temperature detecting element 4 is, for example, a thermistor, and is arranged in contact with the surface of the heater substrate 2 on the side opposite to the side on which the electric heating layer 3 is provided. In this example, the temperature of the heater substrate 2 is used as the temperature of the heating element 1 to be detected by the temperature detecting element 4.

The transfer material 9 carrying the unfixed toner image 10 on the upper surface, which is conveyed from the image forming section (A) side to the fixing device by the image forming start signal in response to the image forming start signal, is guided by the guide. Then, the unfixed toner image surface enters the space between the pressure roller 8 and the fixing film 5 at the pressure contact portion N (fixing nip portion) between the heating body 1 and the pressure roller 8, and the unfixed toner image surface is in the surface movement state While passing through the fixing nip portion N between the heating body 1 and the pressure roller 8 while being in close contact with the lower surface of the heating element 1 and causing no surface deviation or wrinkling, the moving fixing film 5 passes through the fixing nip portion N between the heating element 1 and the pressure roller 8.

The toner image bearing surface of the transfer material 7 receives the heat of the heating element layer 3 through the fixing film 5 while passing through the fixing nip portion N in a pressure-contact state with the fixing film surface, so that the toner image has a high temperature. Melt and soften and adhere to transfer material 9 surface 10a
To do.

In the apparatus of this embodiment, the transfer material 9 and the fixing film 5 are separated from each other when the transfer material 9 passes through the fixing nip portion N and comes out.

The transfer material separated from the fixing film 5 is guided by a guide to be solidified while reaching the paper discharge portion, and the transfer material on which the image is fixed is output.

(2) Control of power supply to heating element The heating element layer 3 of the heating element 1 is energized from both ends in the longitudinal direction thereof as shown in FIG. 2, and the AC current from the AC power source 11 is controlled by a power control element such as a triac. For example, the wave number is controlled by 12. The arithmetic processing unit 13 controls the power control element 12 as follows based on the signal from the temperature detection element 4.

Now, the target temperature of the fixing device is constant at 165 ° C., and for the purpose of finely controlling the electric power at a temperature in the vicinity thereof,
The power supply amount is changed with respect to the temperature in five stages.
The detection temperature is divided into 159 ° C, 163 ° C, 169 ° C, and 177 ° C and classified into 5 stages. Electric power is supplied in the waveform pattern of, for example, the A group in FIG. 3 corresponding to the classified temperatures.

Here, the supply waveform to the heating element layer 3 has a period of 20 msec, a control unit of 8 half-waves, and a maximum supply amount of 8 waves, 7, 6, 5, 4, 3 waves. 2 waves,
The control is divided into 9 types of 1 wave and 0 wave, and one control group is controlled by 5 types of wave numbers. Further, here, it is divided into three control groups A to C. Then, the control group is determined by the flow shown in FIG.

The rate of temperature rise is defined as the time from 100 ° C to 150 ° C. First, the control group is provisionally set in advance to, for example, the A group (S1). When the processor 13 starts energization, it sequentially detects the temperature, selects a waveform corresponding to the temperature from the A group, and supplies the power. Here, when the initial temperature is 100 ° C. or higher, the process jumps to S8. When the initial temperature is 100 ° C. or lower, the process proceeds to S3 (S2).

When the detected temperature exceeds 100 ° C. (S3),
The timer starts counting up (S4) and stops counting when it exceeds 150 ° C (S5). Since the maximum supply of 8 waves is constantly supplied until the temperature exceeds 159 ° C., the temperature rise rate reflects variations in the heater itself, environmental temperature, and the like.

A control group corresponding to the temperature rise rate is selected according to Table 1 (S6), and after the temperature exceeds 150 ° C., the selected control group is moved to (S7).

Table 1

[0029]

[Table 1] In FIG. 5, since the temperature increase rate is 1.28 seconds, the control is moved to the B group. FIG. 5 is a plot of the time change of the temperature of the fixing device in this embodiment.

In S8, it is assumed that the power is already supplied at least once before this, and control is performed based on the previous group information.

<Second Embodiment> (FIGS. 6 and 7) A second embodiment will be described according to the flow of FIG.

In this embodiment as well, as in the first embodiment, the electric power is wavenumber controlled. The rate of temperature rise is defined as the temperature one second after exceeding 100 ° C.

First, a control group is previously set to A, for example.
The group is provisionally set (S9). Arithmetic processing device 13
When the power supply is started, the temperature is sequentially detected, and a waveform corresponding to the temperature is selected from the group A and power is supplied. Here, when the initial temperature is 100 ° C. or higher, the process jumps to S16. When the initial temperature is 100 ° C. or lower, the process proceeds to S11 (S10).

When the detected temperature exceeds 100 ° C. (S11)
The timer starts (S12), and the temperature at the time when one second has elapsed (S13) is detected.

A control group corresponding to the temperature rise rate is selected according to Table 2 (S14), and after the temperature exceeds 150 ° C., the selected control group is moved to (S15).

Table 2

[0037]

[Table 2] In FIG. 7, since the temperature increase rate is 145 ° C., the control is moved to the B group. FIG. 7 is a plot of the time change of the temperature of the fixing device in this embodiment.

In S16, it is assumed that the power has been supplied at least once before this time, and control is performed based on the previous group information.

<Embodiment 3> (FIG. 8) In this embodiment, the power is phase controlled. Similar to the above-described embodiment, the phase angle is controlled as shown in FIG.
Then, the control group is selected according to the flow described above.

[0040]

As described above, according to the present invention, after the start of energization of the heating element, the rate of temperature change during the preset period is measured, and the control group of the supplied power is set according to the measurement result. By changing the heater resistance value, it is possible to supply appropriate power without presetting the heater resistance value or in the image heat fixing device without temporarily energizing at the start of copying. Can be kept constant.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a heat fixing device according to an embodiment.

FIG. 2 is a block diagram of a power control circuit according to the first and second embodiments.

FIG. 3 is a selection diagram of supply power waveform groups in the first and second embodiments.

FIG. 4 is a flowchart of electric power control according to the first embodiment.

FIG. 5 is a graph showing a temporal change in detected temperature according to the first embodiment.

FIG. 6 is a flowchart of electric power control according to the second embodiment.

FIG. 7 is a graph showing a temporal change in detected temperature according to the second embodiment.

FIG. 8 is a power supply waveform group diagram in the third embodiment

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating body 2 Heater substrate 3 Heating element layer 4 Temperature detection element 11 AC power supply 12 Power control element 13 Arithmetic processing device

Claims (2)

[Claims] 1. A detection means for detecting the temperature of an electric heating element or a heating element including the same, and a temperature time within a preset period of the electric heating element or heating element from a signal of the detecting means. A heating body control device comprising: a measuring unit that measures the dynamic change rate; and a power control unit that controls the electric power supplied to the energization heating unit based on the measurement result of the measuring unit. 2. A low-heat-capacity linear heating element, a detection means for detecting the temperature of the heating element, and a temperature of the heating element within a preset period from a signal of the detection means. And a power control device for controlling the power supplied to the heating element based on the measurement result of the measuring means.