JPH06266262A - Fixing device - Google Patents

Abstract

PURPOSE:To shorten the time until the surface of a fixing roller reaches a prescribed temperature as required by constituting a fixing device with the fixing roller having heaters built in and a pressure roller, and arranging multiple heaters having the same output in the fixing roller. CONSTITUTION:A fixing device is constituted of a fixing roller 12 having heaters built in and a pressure roller pressed to the fixing roller 12, a toner image is thermally transferred on a sheet from a photoreceptor at a transfer section, two heaters 10a, 10b having the same output are arranged in the fixing roller 12, and they are properly switched on as required. Only the heater 10a is switched on for facsimile reception, and both heaters 10a, 10b are concurrently switched on in the copy mode to shorten the fast copy time. Switching only the heater 10a on or switching both heaters 10a, 10b on can be selected by a user via an action input from the outside. The number of heaters to be switched on can be selected by the set time of a timer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roll type fixing device applied to an image forming apparatus such as a copying machine or a facsimile using an electrostatic transfer system.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of an image forming apparatus having a heat roll type fixing device, in which 1 is a belt-shaped photoconductor around which a charging section 2 and an exposure section are arranged in the order of an image forming process. 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and a charge eliminating unit 7 are arranged. Further, the sheet P is conveyed by a conveying roller 8 from a sheet feeding unit (not shown). A fixing device 9 is provided with a heater 10 inside and a separating claw on the outer periphery.
The fixing roller 12 is in contact with the fixing roller 12, and the pressure roller 13 is configured to press the fixing roller 12. A paper discharge roller 14 is provided on the downstream side of the fixing device 9.

In such a structure, the unfixed toner image transferred onto the sheet P by the well-known electrophotographic process is heated when the sheet P is nipped by the fixing roller 12 and the pressure roller 13 and heated. It is designed to be fused and fixed.

[0004]

By the way, a user who uses a facsimile machine, especially a laser facsimile machine, often uses this as a copying machine, but the problem here is the length of the first copying time.

That is, when used in the facsimile mode, since the machine operates in an unmanned state because it is received from the other party, there is no concern about the length of the first copy time. If you want to use it with, it is desirable to speed up the start-up of the fixing device and shorten the first copy time.
In the conventional fixing device, since the fixing roller has only one heater built therein, there is a problem that the first copy time becomes long.

An object of the present invention is to provide a fixing device capable of changing the rise time of the heater as necessary and consequently shortening the first copy time.

[0007]

In order to achieve the above object, a fixing device of the present invention comprises a fixing roller with a built-in heater and a pressure roller pressed by the fixing roller. A fixing device for thermally fixing a toner image transferred onto a sheet is characterized in that two heaters having the same output are arranged in the fixing roller.

Further, the number of lit heaters can be switched between the copy mode and the facsimile mode on the image forming apparatus side.

Further, the number of lit heaters can be selected by an operation input from the outside.

Further, a timer is provided, and the number of lit heaters can be selected according to the set time of the timer.

[0011]

According to the fixing device having the above-described structure, by disposing two heaters having the same output in the fixing roller, the rise time until the surface of the fixing roller reaches a predetermined temperature can be shortened if necessary.

Since the number of heaters to be turned on can be selected in the copy mode and the facsimile mode, for example, by turning on both of the heaters in the copy mode, the first copy time in the copy mode is shortened. .

The number of heaters to be turned on can be selected by the user so that the rise time of the heater can be controlled.

Further, by switching the number of heaters to be turned on at the set time of the timer, for example, by turning on two heaters in the daytime and one heater in the nighttime, the electric power can be effectively used.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of the main part of the fixing device according to the first embodiment. Specifically, it shows a fixing roller and a heater arranged inside the fixing roller.
Book heaters 10a and 10b are arranged and, as shown in a flow chart described later, lighting is appropriately controlled as necessary. That is, there are cases where only the heater 10a is turned on and cases where both the heaters 10a and 10b are turned on. Each embodiment of the heater control will be described below. In each flowchart, the heater 10a is shown as the heater A and the heater 10b is shown as the heater B.

FIG. 2 is a flow chart showing the heater lighting control contents according to the first embodiment. First, it is judged whether the mode is a facsimile mode or a copy mode (S1), and in the case of facsimile reception which is often received when unattended, Since the rise time is not a concern, only one of the heaters A is turned on (S2), and in the copy mode where it often stands in front of the machine, two heaters A and B are turned on at the same time (S3). ),
Aim to shorten the first copy time.

FIG. 3 is a flow chart showing the heater lighting control contents according to the second embodiment. In this embodiment, it is left to the user to select the lighting of only one heater A and the lighting of two heaters A and B. Is. Depending on the user, there are various people who stand by in front of the machine even when receiving a facsimile and wait for the output, so that it is considered that only one heater A needs to be turned on at the time of copying. Therefore, all users should be able to select either one-touch operation.

That is, if the heater A is selected in step S11, only the heater A is turned on (S12), and if both A and B are selected, both the heaters A and B are turned on (S13).

FIG. 4 is a flow chart showing the heater lighting control contents according to the third embodiment, in which the heater control is divided into the time when the person is in front of the machine (daytime) and the time when he is not (night). is there. When a certain time arrives (for example, when returning to work) (turned on in S21), only one heater is turned on by the timer (S22). This is enough because there are no people. In the daytime, both heaters A and B are turned on (S2
3).

[0021]

As described above, in the fixing device of the present invention, according to the structure of the first aspect, two heaters having the same output are arranged in the fixing roller, so that the fixing roller can be used as needed. It is possible to shorten the rising time until the surface of the substrate reaches a predetermined temperature.

Further, according to the second aspect of the invention, by turning on both of them in the copy mode, the first copy time in the copy mode can be shortened.

According to the third aspect of the invention, the number of heaters to be turned on can be selected by the user, so that the rise time of the heater can be controlled.

According to the fourth aspect of the invention, the two heaters are turned on in the daytime and one heater is turned on in the nighttime, so that the electric power can be effectively used.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a fixing device according to a first exemplary embodiment of the present invention.

FIG. 2 is a flowchart showing details of heater lighting control according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing details of heater lighting control according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing details of heater lighting control according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of an image forming apparatus having a heat roll type fixing device.

[Explanation of symbols]

9 ... Fixing device, 10 (10a, 10b) ... Heater, 12 ... Fixing roller, 13 ... Pressure roller.

Claims (4)

[Claims] 1. A fixing device comprising a fixing roller having a built-in heater and a pressure roller for applying pressure to the fixing roller, wherein the toner image transferred from a photoconductor to a sheet at a transfer portion is thermally fixed. A fixing device having two heaters of the same output disposed therein. 2. The fixing device according to claim 1, wherein the number of heaters to be turned on can be switched between a copy mode and a facsimile mode on the image forming apparatus side. 3. The number of lights of the heater can be selected by an operation input from the outside.
Or the fixing device described in 2. 4. The fixing device according to claim 1, wherein a timer is provided, and the number of lit heaters can be selected according to the set time of the timer.