JPH02226284A - Fixing device for electrophotographic printer - Google Patents

Abstract

PURPOSE:To accomplish preventing the yellowing fault of the printed part of paper due to overheating by ejecting transferred paper while performing a fixing process for it if continuing paper is stopped for more than a prescribed time during printing operation. CONSTITUTION:The fixing device 4 is provided with a counter 10 which counts a stopping time based on a stopping signal if feeding the paper 1 is stopped during the printing operation and a control part 11 which judges if the paper 1 is ejected or not and controls an ejecting roller 9. If the control part 11, a time until the paper 1 beings to yellow due to yellow due to heating is stored in advance. Then a signal for stopping printing is inputted and the time counter 10 starts counting the time. When the counted time reaches the set time, the control part 11 calculates the number of pages to be ejected, drives the ejecting roller 9 and forcedly ejects paper having a fixed image of the set length of the paper to be ejected while fixing the paper by a plate heater 7 and a roller heater 8 if a reason why the printing operation is stopped is proven to be waiting printing data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for an electrophotographic printer that prints on continuous paper.

[Conventional technology]

A conventional fixing device for this type of printer will be described with reference to the drawings.

FIG. 3 is a block diagram showing this type of electrophotographic printer using a conventional fixing device.

In the figure, a photosensitive drum 2 forms a toner image on continuous paper (hereinafter referred to as paper) 1 along the conveyance line, a transferred toner image 3 transfers the toner image onto the paper 1, and a transferred toner image is fixed. A fixing device 4 is arranged in this order.

The fixing device 4 includes a plate 1-heater 7 that melts the toner on the paper 1 by heating, a roller heater 8 that heats and presses the paper 1 between a pair of rollers facing each other across the paper conveyance line, and a roller heater 8 that applies tension to the paper 1. a paper tension section 5 that gives
A paper brake 6 that prevents the paper 1 from moving backwards, and a paper brake 6 that prevents the paper 1 from moving backwards.
It has a discharge roller 9 that pulls out and discharges. The paper 1 sent out from the supply section is first fed into the transferred 3, and the toner image formed on the surface of the photosensitive drum 2 is transferred to the paper 1.
is transferred to the surface of
The paper 1 that has been subjected to the pressure bonding process and has the toner image fixed thereon is discharged by a discharge roller 9 . This fixing device 4 uses the tension between the ejection roller 9 and the paper tension unit 5 to transfer the paper 1 to the plate heater 7 in order to ensure the stability of paper feeding when printing is restarted when paper feeding stops during printing.
They are kept on standby in close contact with the

[Problem to be solved by the invention]

The printing speed of recent electrophotographic printers has been improving year by year, and more and more printers are being connected online. Therefore, it is inevitable that printing will stop midway due to online waiting for print data.

However, the above-described conventional fixing device continues to heat the paper 1 using the plate heater 7 and roller heater 8, which are controlled within a set temperature range, even when printing is stopped, resulting in yellowing of the printed portion of the paper 1. It had the following drawback.

Yellowing of the printed portion of the paper 1 is difficult to detect immediately after printing, and often becomes a problem after the paper reaches the user, and can be a serious problem in print quality.

An object of the present invention is to provide a fixing device that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a fixing device for an electrophotographic printer that heats and melts the toner image on the continuous paper in a fixing section while conveying the continuous paper. A time counter that counts the stoppage time when feeding stops, and a time when the continuous paper starts to change color due to heating are memorized in advance, and the time counter is monitored so that the continuous paper starts to change color before reaching the set time. The control section drives the ejection mechanism to fix the transferred toner image and forcibly ejects the continuous paper containing the toner image beyond the fixing section page by page.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an electrophotographic printer equipped with a fixing device of the present invention.

In the figure, the toner image formed on the photosensitive drum 2 is transferred by the transferred 3 while the paper 1 is fed on the conveyance line, and then fixed by the fixing device 4 to print.The process and device configuration are shown in FIG. is the same as The fixing device 4 of the present invention includes:
When the feeding of the paper 1 stops during printing, a time counter 10 counts the stop time based on the stop signal, and an ejection roller 9 determines whether or not to eject the paper 1 and feeds the paper 1 by a predetermined feed amount. It is equipped with a control section 11 that controls the.

FIG. 2 is a flowchart showing a method of controlling the discharge roller 9 by the control section 11. When the print stop signal is input, the time counter 10 starts counting time.

The control unit 11 stores in advance a time period until the paper 1 starts to turn yellow due to heating. The control unit 11 monitors the time counter 10 and determines whether the count time has reached the set time. The set time is determined by actually measuring the time required for the paper that is most likely to yellow to turn yellow at the upper limit of the set temperature of the plate heater 7 and roller heater 8 forming the fixing section, and is set to a time slightly shorter than the measured time.

When the count time reaches the set time, the control unit 11 checks the reason for stopping printing, and allows paper to be ejected only when it is confirmed that the print data is waiting.
If printing is stopped due to this, it is determined that paper ejection is not possible.

This determination as to whether or not the paper can be ejected is to determine whether printing quality can be guaranteed when the paper is ejected.

When it is determined that the paper can be ejected, the minimum ejection length F (inches) of the paper that needs to be ejected corresponds to the length of the conveyance line between the transferred paper 3 and the roller heater 8, but it may vary depending on the number of paper pages used. There may be cases where the page is only ejected to the middle of a certain page, or it may be ejected unnecessarily. For this purpose, the control unit 11 calculates the number n of pages to be ejected each time printing is stopped, and ejects the paper 1 by the ejection paper length L (inches) corresponding to the paper length for the number n of pages from the ejection port 9. let The number n of ejected pages is calculated based on the relationship n≧F/P with the minimum ejected length F, where the paper length per page is P (inch), and the ejected paper length is set as L=Pn. When the discharge paper length is set, the controller 1
1 drives the ejection roller 9, and while fixing the unfixed image by heating and pressing with the plate heater 7 and roller heater 8, the final page having the fixed image is forcibly ejected.

〔Effect of the invention〕

As explained above, according to the present invention, when the paper is stopped for a certain period of time during printing due to waiting for print data from online etc., the transferred paper is ejected while undergoing the fixing process, thereby preventing overheating. This has the effect of being able to prevent yellowing of the printed portion of the paper, and providing the user with high-quality print without yellowing.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a printer using the fixing device of the present invention;
FIG. 2 is a flowchart showing a control method in the control section of FIG. 1. 1... Continuous paper 3... Transferred 5... Paper tension section 7... Plate heater 9... Discharge roller 11... Control section

Claims (1)

[Claims] (1) In the fixing device of an electrophotographic printer, which heats and melts the toner image on the paper in the fixing unit while conveying the continuous paper, if the feeding of the continuous paper stops in the middle of printing, the stoppage occurs. A time counter for counting time and a time at which continuous paper begins to change color due to heating are stored in advance, and the time counter is monitored to drive a discharge mechanism before reaching a set time at which continuous paper starts to change color.
1. A fixing device for an electrophotographic printer, comprising a control section that fixes a transferred toner image and forcibly discharges continuous paper containing the toner image page by page beyond the fixing section.