JPH04277781A - Fixation controller - Google Patents

Abstract

PURPOSE:To raise the temperature of a pressure roller to specific temperature under simple control at the time of fixation, to prevent a defect in fixation, and to prevent the service life of the roller from becoming short by detecting the opening or closing of a document pressure plate and rotating a fixing roller for a constant time. CONSTITUTION:A microswitch 21 which is operated by the opening or closing of the document pressure plate is provided at the position where a document is pressed by the document pressure plate at the side part of contact glass where the document is mounted, and an opening or closing detection signal is inputted to a CPU 23; and a fixation motor 24 is started and stopped and the fixing roller 2 is placed in preliminary rotation for the constant time through a timer 30. Consequently, heat is conducted from the fixing roller 2 to the pressure roller 3, the fixing roller 2 is heated by a heater to rises in temperature to the specific proper temperature for the fixation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing control device for a copying machine having a heat roller fixing device.

0002

2. Description of the Related Art As shown in FIG. 4, a fixing device for an electrophotographic copying machine includes a fixing roller 2 that has a built-in heater 1 and rotates, and an elastic layer 3 that is in pressure contact with the fixing roller 2 and rotates as a driven roller.
A transfer paper 6 carrying an unfixed toner image 5 is passed between the transfer paper 6 and a pressure roller 4 having a pressure roller 4, and the toner image is fused and fixed on the surface of the transfer paper 6 by heat and pressing force. Heat roller fusing devices are widely used.

In this type of fixing device, copy fixing is performed by the amount of heat transferred from the fixing roller 2 to the transfer paper and the unfixed toner image, so the temperature of the fixing roller and the temperature of the pressure roller contribute. In this type of fixing device, the surface temperature of the fixing roller is usually detected by temperature detection means 7 such as a thermistor, and the heater 1 is turned on and off based on its output.
The off control is performed to maintain the surface temperature of the fixing roller at a predetermined temperature suitable for fixing. However, the temperature of the pressure roller is usually not detected. When the pressure roller is rotating during fixing, heat is transferred from the fixing roller through the transfer paper, and the surface temperature is uniformly suitable for fixing, but if the standby state continues, the pressure roller's surface temperature will drop. The temperature decreases due to heat dissipation to the surroundings except for the portion in contact with the fixing roller. Therefore, when the fusing roller rotates during the next copy, the heat of the fusing roller is taken away by the low-temperature pressure roller that rotates in contact with it through the transfer paper, and the surface temperature of the fusing roller is adjusted to the set fixing temperature. The temperature will drop considerably. As the temperature of the pressure roller increases, the temperature of the fixing roller also recovers, but the first 1 to 3 copies that are fixed without recovery will be insufficiently fixed.

[0004] Therefore, by performing a pre-rotation (pre-rotation) in which the fixing roller starts rotating without passing the transfer paper just before copying, the pressure roller is driven to rotate and the pressure roller is transferred from the fixing roller to the pressure roller. For example, a fixing control method that improves fixing performance from the first sheet by applying heat to raise the temperature and performing fixing after the fixing roller itself has recovered to a predetermined fixing temperature is disclosed in JP-A-63. -253977, etc. However, the pre-rotation control method disclosed in this publication starts the pre-rotation a predetermined time after the start of exposure for copying, and the pre-rotation time is such that the temperature of the fixing roller reaches a predetermined first fixing temperature and a second fixing temperature. We make decisions based on the time it takes to reach the fixing temperature, so
If the temperature of the pressure roller is extremely low, such as during severe cold weather, the transfer paper will be fed into the fixing device before the pressure roller has sufficiently warmed up. Moreover, it seems that complicated control will be required to perform control under the above control conditions.

A control method has also been considered in which the temperature of the pressure roller is maintained at a certain temperature or higher by rotating the fixing roller at certain time intervals during standby, regardless of whether copying is being performed or not. This control method simplifies control, but this control method also has problems because driving the fixing roller frequently to improve the accuracy of the holding temperature will affect the life of the roller. .

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of conventionally proposed control devices for heat roller fixing devices including pre-rotation of the fixing device, the present invention aims to control the pressure roller during fixing by simple control. The temperature has definitely risen to the specified temperature,
It is an object of the present invention to provide a fixing control device that does not have a lifespan shortened due to frequent rotations.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the fixing control device of the present invention provides a copying system that opens the document pressure plate, places the document on a contact glass, and closes the document pressure plate to expose the document. The apparatus is characterized in that it detects the opening or closing of the document pressure plate, and controls the fixing roller to rotate for a predetermined period of time based on the signal.

[0008] Furthermore, in a copying machine in which an automatic document feeder feeds a document onto the contact glass of the copying machine body and exposes it to light, it is difficult to place the document on the document feed section of the automatic document feeder. is detected, and the fixing roller is controlled to rotate for a predetermined period of time based on the signal.

[0009]

[Operation] As described above, in order to expose the document, it is detected that the document pressure plate is opened or closed or that the document is placed on the document feed section of the automatic document feeder, and based on the signal, the document is placed in front of the fixing roller. Since the rotation is started, the forward rotation is automatically started by the operation naturally necessary for exposing the document, even if the operator does not press the forward rotation key or the like. Opening/closing the document pressure plate,
Or, since there is a slight time interval between placing the original in the document feeder and pressing the copy button, start forward rotation after a certain period of time after pressing the copy button, turning on the exposure lamp, or starting scanning with the scanner. The pre-rotation can be performed for a sufficient period of time, and even if the temperature of the pressure roller is low, such as during severe winter, the pressure roller will rise to the required temperature by the time the transfer paper reaches the fixing device. , good fixing properties can be obtained. Control becomes very simple by keeping the pre-rotation time constant. If the temperature of the pressure roller is quite high, it may seem wasteful to perform pre-rotation for a certain period of time, but since the fusing roller is maintained within a certain temperature range by a thermistor, it is possible to prevent the temperature of the pressure roller from becoming high. For example, the temperature difference between the fuser roller and the pressure roller becomes smaller, the amount of heat transferred from the fuser roller to the pressure roller is reduced, and the fuser roller heater is automatically turned off. , the temperature of the pressure roller does not rise unnecessarily, and the amount of heat is not wasted.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a schematic configuration of an example of a copying machine equipped with a fixing control device of the present invention. A contact glass 11 is provided on the top surface of the copying machine main body 10 on which a document is placed for exposure.The document is placed on top of the contact glass 11 by opening the document pressure plate 12 that can be opened and closed by flipping up the rear end. When the document is placed in a closed position and pressed so that it does not move, the document image is imaged on the photoreceptor drum 14 by the exposure optical system 13 provided below the contact glass 11, and the photoreceptor drum is exposed to the photoreceptor drum. It is exposed to light, and an electrostatic latent image is created on the photoreceptor drum 14. A developing device 15, a transfer charger 16, and a cleaning device 17 are provided around the photosensitive drum 14 in the rotational direction indicated by the arrow. The electrostatic latent image is developed into a toner image by the developing device 15, and is transferred onto the transfer paper 6 fed from the paper feed section 18 under the action of the transfer charger 16. The paper is conveyed to the fixing device 19, where it is fixed, the copying is completed, and the paper is discharged to the paper discharge tray 20 outside the machine.

A microswitch 21 is provided on the side of the contact glass 11 at a position pressed by the original pressing plate 12, and is activated by opening or closing the original pressing plate 12. The protruding protrusion 22 can be turned on and off in response to opening and closing of the document pressure plate to transmit a signal. The microswitch 21 and the protrusion 22 may be replaced with a photoelectric sensor and a light shielding plate. The document pressure plate opening or closing detection signal from the microswitch or photoelectric sensor 21 is input to the CPU 23 as shown in FIG. 30 starts and is controlled to rotate for a certain period of time, for example, 30 seconds. After 30 seconds have elapsed, the fixing roller stops rotating. By rotating it for 30 seconds,
Heat is transferred from the fixing roller 2 to the pressure roller 3, the removed heat is given to the fixing roller by the heater, and the temperature of the fixing roller is restored to a predetermined fixing temperature. Since the forward rotation of the fixing roller is started by opening or closing the document pressure plate, the increase in the time required for copying is smaller than when the forward rotation is started by pressing the copy button. Further, the operator does not need to operate a key or the like to command pre-rotation.

Next, in FIG. 1, a contact glass 1
The automatic document feeder 2 shows the feeding of the document onto 1 by the chain line.
5 (Automatic Document
ederADF) will be described. In this case, a sensor 27 is provided in the document feed section to detect that a document is placed on the document feed section 26, and the document placement detection signal from the sensor 27 is used as in the case of using the document pressure plate. The pre-rotation of the fixing roller 2 is started according to the block diagram shown in FIG. 2, and is controlled to stop after rotating for a certain period of time, for example, 30 seconds.

FIG. 3 shows a flowchart of the control flow of the fixing device including the pre-rotation of the fixing roller as described above.

The flow from turning on the power to becoming ready for copying is no different from that of conventional fixing devices.

When the document pressure plate is opened and the document is placed directly on the contact glass, or the document is placed on the ADF's document feed table, the document pressure plate is opened or closed, or the document is placed on the ADF document feed table. The fixing roller position is detected by the sensor 21 or 27, and the fixing roller starts forward rotation, and at the same time, a timer is started, and when the timer reaches 30 seconds, the forward rotation is stopped. Even if the copy button is pressed before that, the copying operation will not start, but after the pre-rotation is performed for 30 seconds, the copying operation will start, and the copying operation will be performed according to a known process, and then the copying operation will be completed.

[0017]

As described above, according to the present invention, the temperature of the fixing and pressure roller can be adjusted to the required temperature for fixing in a short time prior to the fixing operation by simple control by the operation normally performed when copying an original. Since the temperature can be raised to a temperature of
There is no reduction in the lifespan of the pressure roller.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the overall general configuration of a copying machine to which the present invention is applied.

FIG. 2 is a block diagram of the fixing control.

FIG. 3 is a flowchart of the fixing control.

FIG. 4 is a sectional view showing an example of a general configuration of a heat roller fixing device.

[Explanation of symbols]

1 Heat source 2 Fixing roller 4 Pressure roller 5 Toner image 6 Transfer material 10 Copy machine 11 Contact glass 12 Original pressure plate 14 Photoreceptor drum 15 Developing device 19 Heat roller fixing device 21 Original pressure plate opening/closing detection means 24 Fusing motor 25 Automatic document feeder (ADF) 26 Original paper feed section 27 Original placement detection means

Claims (3)

[Claims] [Claim 1] A transfer material carrying an unfixed toner image is passed between a rotating fixing roller with a built-in heat source and a pressure roller that is in pressure contact with the fixing roller and rotates as a result of rotation, thereby transferring the toner image. In a fixing control device of a copying machine, which has a fixing device that performs fusing by fusing to the surface of a material, opens the document pressure plate, places the document on a contact glass, and closes the document pressure plate to expose the document. A fixing control device that detects opening or closing of a pressure plate and controls a fixing roller to rotate for a predetermined period of time based on a signal from the opening or closing of a pressure plate. 2. Transferring the toner image by passing a transfer material carrying an unfixed toner image between a rotating fixing roller that has a built-in heat source and a pressure roller that is in pressure contact with the fixing roller and rotates as a result of the rotation. It has a fixing device that fuses and fixes the document to the surface of the material, places the document on the paper feed section of the automatic document feeder, and feeds the document onto the contact glass of the copying machine by the automatic document feeder. The fusing control device of a copying machine that feeds and exposes a document detects that the document is placed on the paper feed section of the automatic document feeder, and uses that signal to rotate the fusing roller a certain period of time. A fixing control device characterized by controlling. 3. The fixing roller according to claim 1, wherein if the copy button is not pressed within the predetermined time period, the fixing roller is controlled to stop rotating after rotating for a predetermined time period.
Or the fixing control device according to 2.