JPS60149070A - Fixing device - Google Patents

Abstract

PURPOSE:To heat a pair of fixing bodies up to a fixing set temperature in a short time by forming a control means for heating the fixing bodies under separated state up to a prescribed time enabling the fixing bodies to fix and then pressing the fixing bodies. CONSTITUTION:When a heater 27 generates heat and the temperature of a fixing roller 25 is detected by a temperature detecting sensor 35 and reaches the temperature of a glass transition point, a driving circuit 28 is actuated by a microcomputer 29 and a pressing rollr 26 is pressed against a fixing roller 25. When the rotating time of the fixing roller 25 and the pressing roller 26 has passed a prescribed time and the temperature of the fixing roller 25 reaches the fixing set temperature, a control circuit 33 is actuated and a ready signal for the completion of fixing preparation is displayed on a control panel 38. The temperature of the fixing roller 25 is kept at the fixing set temperature T2 by controlling power supply by the microcomputer 29. Thus, the fixing roller can be heated up to a required temperature for a short time without absorbing the heat of the fixing roller 25 by the pressing roller 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a heat roller type fixing device provided in, for example, an electronic copying machine, a facsimile machine, and the like.

[Technical background of the invention and its problems]

This type of fixing device consists of a pair of rollers for fixing and applying pressure, and the fixing roller is heated at a temperature of 15 to 2
The image is heated to 00° C. and the image is fixed by passing the image-transferred paper between these rollers.

However, conventionally, the fixing roller is heated by a heater at the same time as the power switch is turned on, and at this time, the pressure roller is rotated by the rotation of the fixing roller in a pressurized state, so the temperature of the fixing roller does not increase. Heat was continuously being taken away by the pressure roller, and it took a long time to reach the set fixing temperature.Also, there was a small amount of toner that adhered to the fixing roller after the transfer paper passed, and the member that cleaned it was the fixing roller. The fixing roller is placed in pressure contact with the fixing roller.Furthermore, a temperature detection sensor is attached to the fixing roller via a low-friction, heat-resistant film.If the fixing roller is used for a long time, the surface of the fixing roller may be damaged. , it becomes easier for toner to adhere to its surface, and this adhered toner adheres to the cleaning member or the film on the surface of the temperature sensor.When the fuser is not in use, it is cooled to room temperature, and the bonding force between the adhered toner and the fixing roller increases. It is getting bigger.For this reason,
When the fixing roller rotates, a large force is applied to the temperature detection sensor, which may cause the temperature detection sensor to break, or the fixing roller surface may be damaged by toner adhering to the cleaning member or sensor film surface, which may further cause toner adhesion. This created a vicious cycle of overexposure and shortened the lifespan of the fixing roller and sensor.

Therefore, as a solution to the above-mentioned problems, it has been considered to separate the fixing roller and the pressure roller until the fixing set temperature is reached, so that no pressure is applied and the nip rotation is not driven. There was an inconvenience that temperature unevenness occurred in the longitudinal direction. Furthermore, there is a drawback that auto-coo shoot occurs when the fixing temperature is exceeded.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to enable the fixing body to reach the set fixing temperature in a short period of time, without damaging the fixing body or the sensor, and to It is an object of the present invention to provide a fixing device that does not cause uneven body temperature.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention is provided with a control means that heats a pair of fixing bodies in a separated state for a predetermined period of time at which fixing is possible, and then brings them into pressure contact.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. In the figure, reference numeral 1 denotes the main body of an electronic copying machine, and a mounting table 2 on which a document is placed is provided on the upper surface of the main body 1, and the original on this mounting table 2 is covered by a document cover 3. There is.

Further, on the upper side of the main body 1, there are lamps 4, first to third lamps.
An exposure scanning system 10 is provided which includes mirrors 5, 6, and 7, a lens 8, and a fourth mirror 9. Further, a photosensitive drum 11 is rotatably provided in the center of the main body 1, and a charger Z2, a charger Z2,
Developing device 13, transfer and peeling charger 14a, 14
b and a cleaning device 15 are provided.

Further, first and second paper feed cassettes 16 and 17 are provided at the lower part of one side of the main body 1, and furthermore, a manual paper feed tray 18 is provided at the upper part of the first paper feed cassette 16. There is. The paper fed from the first and second paper feed cassettes 16 and 17 and the manual paper feed table 18 is fed to the feed path 19.
The data are sent to the registration rollers 2o through the respective registration rollers 2o. Further, reference numeral 21 denotes a conveyor belt that conveys the paper that has passed below the photosensitive drum 11, and the sheet that has been conveyed by this conveyor belt 21 is sent to a fixing device 22. The paper that has passed through the fixing device 22 is ejected to a paper ejection tray 24 via a paper ejection roller 23.

Next, the recording and fixing device 22 will be described in detail.

This fixing device 22, as shown in FIG.
6. The fixing roller 25 is equipped with a heater 27.
is installed inside. Further, as shown in FIG. 3, the pressure roller 226 is connected to a microcomputer 29 as a control means via a drive circuit 28, and the fixing roller 226 is connected to a microcomputer 29 as a control means.
6 is connected to the microcomputer 34 via the motor drive circuit 3o. Further, the heater 27 is connected to the microcomputer 34 via a power source 3I and a control circuit 32. In addition, 38 indicates the fixing preparation is complete.
The control panel 38 is connected to the microcomputer 29 via a control circuit 33. A temperature detection sensor 35 is in contact with the fixing roller 25, and the temperature detection sensor 35 is connected to the microcomputer 29 via a thermistor control circuit 36. In the microcomputer 29, the temperature detection sensor 35 detects the fixing set temperature T and a lower predetermined temperature T1 (TI is set to the glass transition point temperature of the toner of 50 to 80 degrees Celsius or higher).
When detected, an operation command is given to the drive circuit 28 of the pressure roller 26 and the drive circuit 30 of the fixing roller 25, the fixing set temperature T2 is detected, and the fixing temperature is set for a predetermined time t0.
After the time has elapsed, an operation command is given to the controller circuit 33. Note that 41 in the figure is a cleaner that comes into contact with the surface of the fixing roller 25 and removes toner adhering to the surface.

During image formation, the original on the mounting table 2 is scanned and exposed by the exposure scanning system 10, and an electrostatic latent image thereof is formed on the surface of the photosensitive drum 11, which is uniformly charged by the charger 12. This electrostatic latent image is sent to a developing device 13 by the rotation of the photosensitive drum 1z, and a tozo is supplied from the developing device 13 to make it visible. Also, at this time, the first or second
Paper is supplied from the paper feed cassette 16, 17 or the manual feed stand Z8, and is transferred to the photosensitive drum I via the registration roller 20.
I and the transfer/separation chargers 14a, 14b. Here, the developed image on the photosensitive drum IZ is transferred to paper by the action of the transfer charger 14h, and then peeled off from the photosensitive drum z1 by the action of the peeling charger 14b, and sent to the fixing device 22 via the conveyor belt 2I. . Then, the image is fixed by passing between the fixing roller 25 and the pressure roller 26 of the fixing device 22, and the sheet is discharged to the paper discharge tray 24 via the paper discharge roller 23.

Incidentally, during image formation, the power switch 37 of the fixing device 22 is turned on as shown in the flowchart of FIG. 4, and the heater 27 of the fixing roller 25 generates heat.

The temperature of this fixing roller 25 is measured by a temperature detection sensor 3.
5, and when the temperature reaches a predetermined temperature TI (glass transition point temperature), the drive circuit 28 is activated by the microcomputer 29 to press the pressure roller 26' against the fixing roller 25, and the motor drive circuit 30
The fixing row 225 is rotationally driven through. Then, when the rotation time t2 of the fixing and pressure roller 26 has elapsed and the temperature of the fixing roller 225 reaches the fixing set temperature T2, the control circuit 33 is activated and outputs a ready signal indicating that fixing is ready. Displayed on page 38.

Also, the temperature of the fixing roller 25 is
The power supply from the power source 31 is controlled by the signal from 9 to maintain the fixing set temperature T.

As described above, since the fixing roller 25 is heated with the fixing roller 25 and the pressure roller 26 separated from each other, the heat of the fixing roller 225 is not taken away by the pressure roller 26.
It can be heated to the desired temperature in a short time.

Furthermore, since the fixing roller 25 and the pressure roller 26 are brought into pressure contact when the temperature reaches a predetermined temperature T8 lower than the fixing set temperature T2, it is possible to prevent overshoot on the surface of the fixing solar 25 as shown by the solid line a in FIG. As shown by the broken line in the figure, temperature unevenness in the longitudinal direction can also be reduced as much as possible.

In addition, the broken line in FIG. 5 indicates the fixing roller 25 and the pressure roller 2.
The fixing roller 25 is set at the fixing temperature T with
This shows the case where the pressure roller 226 is brought into pressure contact with the fixing roller 225 after heating the fixing roller 225 to a temperature of It will happen. Further, a dotted line C in FIG. 5 shows the case where the fixing roller 25 and the pressure roller 26 are heated in a state in which they are in pressure contact with each other, and in this case, it takes a long time to reach the fixing set temperature T2.

〔Effect of the invention〕

As explained above, in the present invention, a pair of fixing bodies are separated and heated to a predetermined temperature at which fixing is possible, and then brought into pressure contact with each other, so that the warm-up time can be shortened and the fixing time can be shortened compared to the conventional method. Temperature unevenness in the longitudinal direction of the body can be reduced and good pressure fixing can be achieved. Additionally, even if developer adheres between the fuser and the cleaner and temperature sensor, it can be softened, preventing damage to the surface of the fuser and preventing disconnection of the temperature sensor. It has the effect of being able to do it.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic configuration diagram showing an electronic copying machine, FIG. 2 is a side view showing a fixing device, FIG. 3 is a schematic configuration diagram showing a control circuit, and FIG. Figure 4 is a flowchart showing the flow of operation, Figure 5 is a graph showing the temperature change of the fixing roller compared to the conventional one, and Figure 6 is a graph showing the temperature distribution in the longitudinal direction of the fixing roller compared to the conventional one. It is a diagram. 25... Fixing body (fixing roller), 26... Fixing body (
(pressure roller), 29...control means (microcomputer), T8...predetermined temperature, Tt...fixing set temperature. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 8 Yu Figure 2 Figure 6 Figure 3 Figure 4 Figure 5 S giant trap

Claims (3)

[Claims] (1) In a device that heats and presses a fixing object with a pair of fixing bodies that move toward and away from each other to fix the fixing target, after heating the fixing body to a predetermined temperature at which fixing is possible while the pair of fixing bodies are separated, A fixing device characterized by comprising a control means for press-contacting the fixing device. (2) The fixing device according to claim 1, wherein the body to be fixed is made of toner, and the predetermined temperature is a temperature equal to or higher than the glass transition point of the toner. (3) After a predetermined temperature is reached, when a predetermined period of time has elapsed after the fixing body has been in pressure contact with the fixing body and the fixing body has reached the fixing set temperature, it is displayed that the fixing preparation is complete. The fixing device according to item 1 or 2.