JPH04319964A - Copying method and copying device - Google Patents

Abstract

PURPOSE:To enable recording sheet transfer intervals to be selectively changed over depending upon a purpose by extending the intervals when high fixing quality is required, and shortening the intervals when a high processing rate is required. CONSTITUTION:Documents are sequentially fed onto contact glass repeatedly several times corresponding to the number of copies. Each document is exposed on<be onto a photosensitive drum 5 via an exposure optical system 4, and a toner image is formed on the drum 5 via an electrostatic photographing process. Then, the toner image formed on the photosensitive drum 5 is transferred to a recording sheet 7 fed from a sheet feed section 6. In this case, the sheet feed section 6 is provided with two sheet feed trays 10 and 11, and a manual sheet feed tray 12. The trays 10 to 12 are selectively changed over for feeding sheets. When the manual sheet feed tray 12 is selected, or turned from storage state to service state, recording sheet feed intervals are automatically so selected as to be longer than the case of using the ordinary trays 10 and 11, interlocked with the operation of the manual sheet feed tray 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying apparatus and a copying method having a heat roller fixing device.

0002

2. Description of the Related Art The productivity of a copying machine, that is, the number of copies that can be made per minute (hereinafter referred to as CPM), is an important numerical value representing the performance of the copying machine. As CPM increases, the number of sheets of recording paper that passes through the fixing device per unit time increases, and when a heat roller fixing device is used as the fixing device, the amount of heat taken by the recording paper from the fixing roller increases, so the fixing It is necessary to increase the capacity of the heater.

However, the power supply capacity that can be used for the entire copying machine is limited by the limited capacity of the outlet, which is 15 amperes, and there is a limit to the power that can be supplied to the fixing heater.

[0004] Therefore, copying machines with a high CPM are designed to supply a limit capacity of electric power to the fixing heater to obtain the minimum necessary fixing performance for copying. The above-mentioned minimum fixability required for a copy is, for example, a value such that when a fixed copy is rubbed a certain number of times under a certain pressure, the image density ratio before and after rubbing is 50% or more.

[0005] On the other hand, in recent years there have been increasing opportunities to use photocopied copies as manuscripts, and in such cases,
Using Recycling Document Handler (RDH),
A method in which a series of originals is circulated and copied onto a contact glass a number of times corresponding to the required number of copies has come to be widely used. Therefore, if a single copied original is repeatedly conveyed through the conveyance path many times and comes into contact with the conveyance rollers and guide members and is rubbed, and a copy with poor fixing properties is used as an original, the original image will be Worn and scraped toner adheres to members such as rollers or to the original document itself, staining the original document, causing problems such as stains being copied onto the copied image. Therefore, even if the toner is sufficient for use as a copy, there may be cases where the fixing properties are insufficient for use as an original.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention provides a copying method and a method that can achieve a high throughput when used simply as a copy, and have high fixing properties when producing a copy to be used as an original. , it is an object of the present invention to provide a copying machine suitable for carrying out this method.

[0007]

[Means for Solving the Problems] A copying method for solving the above-mentioned problems of the present invention is a copying method in which a toner image is transferred from a photoreceptor to continuously fed recording paper and fixed by a heat roller fixing device. The present invention is characterized in that the recording paper conveyance interval is controlled to be long when copying requires high fixability, and the recording paper conveyance interval is shortened when copying requires high throughput.

[0008] A copying apparatus suitable for carrying out this method has a plurality of paper feed ports, and a heat roller fixing device that fixes the toner image transferred from the photoreceptor onto the recording paper fed from the paper feed port. In a copying apparatus having a device, the distance between recording sheets when feeding continuously is smaller when paper is fed from one of the plurality of paper feed ports than when paper is fed from other paper feed ports. It is characterized by providing a control means for controlling the length to become longer.

[0009]

[Operation] Since the copying apparatus according to the present invention is constructed as described above, when obtaining a copy to be used simply as a copy, it is possible to record paper by feeding it from a paper feed port that shortens the paper feeding interval. The paper passes through the fixing roller at short intervals, and the fixing performance is minimal but high CPM is achieved.On the other hand, if you want to obtain a copy to be used as an original, paper feeding requires a longer recording paper feeding interval. By feeding paper from the front, it is possible to lengthen the paper feeding interval and reduce CPM, but the time it takes after one recording paper passes the fixing roller until the next recording paper enters the fixing roller During this time, the fixing roller is sufficiently heated and its temperature is increased, and sufficient fixing performance can be obtained.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a schematic configuration of an example of a copying machine suitable for carrying out the method of the present invention. Copy machine body 1
RDH3 is placed on the contact glass 2 provided on the top plate of the
A series of originals are sequentially fed onto the contact glass 2 repeatedly a number of times corresponding to the desired number of copies, and exposed onto the photoreceptor drum 5 once through the exposure system 4. A toner image is formed by an electrostatographic process. The toner image formed on the photoreceptor drum 5 is transferred to a paper feed section 6.
The toner image is transferred to the recording paper 7 fed by the recording paper 7, and the recording paper 7 with the transferred toner image is fixed by the heat roller fixing device 8 to complete the copying and is discharged to the paper discharge tray 9.

The paper feed section 6 has two paper feed trays 10 and 11.
and a manual paper feed tray 12 are provided, and paper can be selectively switched to feed paper from any tray.

In the copying machine of this embodiment, when the manual paper feed tray 12 is selected, that is, the manual paper feed tray 12
When the storage position shown by the solid line in the figure is moved to the use position shown by the chain line, the recording paper feeding interval becomes longer than when using the normal paper feed trays 10 and 11. Automatically switched.

The heat roller fixing device 8 includes a fixing roller 14 having a built-in fixing heater 13 and a pressure roller 1 in pressure contact with the fixing roller 14.
A thermistor 16 is provided in contact with the fixing roller 14 to detect its surface temperature. As shown in FIG. 2, the fixing roller 14 is detected by the thermistor 16.
When the surface temperature is below a predetermined fixing temperature T0, the fixing heater 13 is turned on, and when it exceeds a certain temperature T0, the heater 13 is turned off. When the copying machine is in a standby state (a state in which only the power is on and no recording paper is passing through), the heater 13 is repeatedly turned on and off as shown in FIG.

During copying, when the recording paper passes through the nip between the fixing roller 14 and the pressure roller 15 and is fixed,
The heat of the fixing roller 14 is absorbed by the recording paper and the toner on it, and when continuous copying is performed and the distance between two consecutive recording papers is short, the heat of the fixing roller 14 is also absorbed by the heater 13 as shown in FIG. The temperature of the roller does not recover to T0, and the temperature of the fixing roller 14 becomes stable at T1, which is lower than T0. In this state, the amount of heat taken by the paper from the fixing roller 14 and the amount of heat supplied to the fixing roller 14 by the heater 13 are balanced. That is, during continuous paper feeding, the fixing temperature is T1, which is lower than T0.

Now, there is a relationship between fixing temperature and fixing performance (fixing rate) as shown in FIG. 4, and it can be seen that it is necessary to increase the temperature of the fixing roller in order to improve the fixing performance. Further, it is necessary that the fixing rate is 50% at temperature T1 in a stable state.

FIG. 5 shows the temperature change of the fixing roller when the interval between recording sheets (hereinafter referred to as "paper interval") is changed without changing the conveying speed of the recording sheets during continuous copying. From this figure, it can be seen that the longer the paper distance, the higher the stable temperature of the fixing roller. (The CPM at this time is shown in parentheses for reference.) The reason for this is that the amount of heat supplied to the fixing roller increases when the paper is not passing through.

Therefore, when using the manual paper feed tray 12 in the copying machine of the present invention, if the paper feed interval is controlled to be longer than when using the other paper feed trays 10 and 11, the manual feed When using paper, the stable temperature of the fixing roller is higher than when using other paper feed trays, and high fixing performance can be obtained.

The paper interval during continuous copying is as shown in FIG.
A timer (T1) from feeding one recording paper to feeding the next recording paper, and a timer (T1) from one scanner start signal to the next scanner start signal in the exposure optical system.
T2). In the device of the present invention, this timer is the timer for normal copying (T1-1, T2-
1) Two types of timers (T1-2, T2-2) for high fixing performance are provided, and a sensor detects the switching operation between the storage position and the use position of the manual paper feed tray 12 and switches the timer. It looks like this. Timer (T1-2, T2-
2) is set so that, for example, the paper spacing when the high fixability timer is used is approximately twice the paper spacing when the high throughput timer is used.

As a result of the above, when using the manual paper feed tray, the paper gap during continuous paper feeding is larger than when using other normal paper feed trays, high fixing performance is obtained, and normal paper feeding is possible. High throughput can be obtained when using trays. Note that the switching to increase the paper interval is not limited to the manual paper feed tray, and any one of the plurality of paper feed trays can be set for high fixing performance.

[0020]

As described above, according to the present invention, by switching the recording paper conveyance interval with a simple configuration, continuous copying with high fixing properties and continuous copying with high throughput can be achieved for copy purposes. It can be switched depending on the situation.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an embodiment of a copying machine suitable for carrying out the method of the present invention.

FIG. 2 is a curve diagram showing an example of fixing roller temperature changes during startup and standby.

FIG. 3 is a curve diagram showing an example of balanced fixing roller temperature during continuous copying.

FIG. 4 is a curve diagram showing an example of the relationship between fixing roller temperature and fixing rate.

FIG. 5 is a curve diagram showing an example of a change in fixing roller temperature during continuous copying when the paper spacing is changed.

FIG. 6 is a timing chart of paper feeding and optical scanner scan start during continuous copying.

[Explanation of symbols]

1 Copy machine 2 Contact glass 3 RDH 4 Exposure science 5 Photoreceptor 6 Paper feed section 7 Recording paper 8 Heat roller fixing device 9 Paper output tray 10, 11 Paper feed tray 12 Manual paper feed tray

Claims (2)

[Claims] Claim 1: In a copying method in which a toner image is transferred from a photoreceptor to continuously fed recording paper and fixed by a heat roller fixing device, when copying requires high fixing performance, the recording paper conveyance interval is lengthened to achieve high processing speed. A copying method characterized in that when copying requires a large quantity, the recording paper conveyance interval is controlled to be shortened. 2. In a copying machine having a plurality of paper feed ports and a heat roller fixing device that fixes a toner image transferred from a photoreceptor onto recording paper fed from the paper feed port, continuous paper feeding is performed. A control means is provided for controlling the distance between the recording sheets so that when the paper is fed from one of the plurality of paper feed ports, the distance between the recording sheets is longer than when the paper is fed from the other paper feed ports. A copying device characterized by: