JPS61100776A - Heat fixing device - Google Patents

Abstract

PURPOSE:To start fixing operation immediately after turning on a power supply by embedding a heating element in the peripheral part of a roller. CONSTITUTION:A heat fixing device 17 is provided with a heat roller 20 obtained by embedding e.g. 24 long heating elements 191-1924 on the peripheral part of the roller along the direction of its shaft 18 with a prescribed interval and a press-contact roller 21 pressed into contact with the heat roller 20 to pass paper 12 to be fixed with contact pressure. The gap between the shaft 18 of the heat roller 20 and the embedding part of the heating elements is filled with an heat insulating material 22. Current is supplied to the heating elements during the period from the contact of an electrode with the leading end of the 1st brush 25 (the front of the press-contact part) to the separation of the electrode from the back end of the brush 25 (the press-contact part) to generate heat only for the period. On the basis of the heating operation during the period, the heating elements heat its nearby peripheral part. Consequently, the neighboring part of the heated heating elements is rapidly heated and immediately reached at a temperature proper to fixing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat fixing device used in, for example, electrophotographic printers and copying machines.

[Conventional Vi, Technique] Conventionally, a heat fixing device uses a heat roller in which a heating element is embedded in the center along the axial direction.

[Problems to be Solved by the Invention] However, with this type of device, a relatively long warm-up time is required until the peripheral surface of the roller becomes wet enough for fixing, and therefore, fixing cannot be performed quickly after turning on the power. There was a problem where it could not start working.

This invention was devised to solve these problems, and provides a thermal fixing device that can shorten the warm-up time, start the fixing operation quickly after turning on the power, and further reduce power consumption as much as possible. The purpose is to provide.

[Means for Solving the Problems] The present invention provides a heat roller in which a plurality of elongated heating elements are embedded at predetermined intervals in the circumferential portion along the axial direction, and the heat roller. A member that presses and passes the paper to be fixed under pressure, and a contact mechanism that is formed so as to sequentially contact a predetermined number of heat generating elements from the front of the pressure contact part to the pressure contact part by rotation of a heat roller. and a power source that supplies power to each heating element via this contact mechanism.

[Function] In the present invention having such a configuration, since the heating element is embedded in the circumferential portion of the roller, the peripheral surface near where the heating element is embedded can be quickly heated. Moreover, the electricity supply to the heating element starts a little before the paper comes into pressure contact with the sheet, and the electricity supply to the heating element is stopped after the sheet passes through the pressure contact part.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as applied to an electrophotographic printer.

Figure 1 shows the overall configuration of an electrophotographic printer.
1 is a housing, and 2 is a photosensitive drum provided in the center of the housing 1, the outer peripheral surface of which is formed as a photosensitive surface. The photosensitive drum 2 is rotated at a constant speed by a motor (not shown). Along the circumference of the photosensitive drum 2, a charging charger 3, an irradiation section for exposing laser light 4, a generation device 5 for the laser light, a developing section 6, a transfer charger 7, a static elimination lamp 8, and a wiping roller 9 are arranged. It is arranged.

An insertion slot 1 for a paper feed cassette 10 is provided at the lower side of the housing 1.
1 is formed between the insertion opening 11 and the transfer charger 7, and a paper feed roller 13 and a paper feed guide 14 for guiding the paper 12 stored in the paper feed cassette 10 to the transfer charger 7. is provided. Further, a paper insertion section 15 for manually feeding paper is provided on the side surface of the housing 1.

On the opposite side of the transfer charger 7 to the paper feed guide 14, a transport conveyor 16 and a heat fixing device 17, which is a main part of the present invention, are arranged.

As shown in FIGS. 2 and 3, the heat fixing device 17 includes:
A heat roller 20 is formed by embedding, for example, 24 elongated heating elements 191 to 1924 at a predetermined interval along the direction of the axis 18 in the circumferential portion, and the heat roller 20 is pressed into contact with the heat roller 20 to be fixed. A pressure roller 21, which is a member through which the paper 12 passes under pressure, is provided. The heat roller 20
A heat insulating material 22 is filled between the shaft 18 and the buried portion of the heating element. One end of each of the heating elements 191 to 1924 is connected to electrodes 231 to 2324 which are insulated from each other, and the other end is connected to the common electrode 24. The rotation of the heat roller 20 causes each of the heating elements 1 to
91 to 1924, electrodes 23 to which predetermined, for example, six heating elements are connected, which extend from this side of the pressure contact part to the pressure contact part.
A first brush 25 as a contact mechanism that sequentially contacts the common electrode 24 and a second brush 26 that contacts the common electrode 24 are provided. The first brush 25 slides on the electrodes 231 to 2324 when the heat roller 20 rotates, and when the heat roller 20 is in the state shown in FIG.
comes into contact with the connected electrodes 237-2312.

A terminal of the first brush 25 is connected to the negative electrode side of a DC power source 27. The terminal of the second brush 26 is connected to the power supply 2 via a switch 28 that responds to the ON signal of the motor.
It is connected to the positive electrode side of 7.

In the device of this embodiment having such a configuration, when a motor ON signal is generated, the motor turns the heat roller 20
And the pressure roller 21 rotates in the direction shown by the solid arrow. Also, the switch 28 is turned on. Thus, the six heating elements connected to the electrode 61IM that is in contact with the first brush 25 are energized. This heating element is energized in the first
This is performed from when the electrode comes into contact with the tip of the first brush 25 (before the pressure contact part) until the electrode separates from the rear end of the first brush 25 (at the pressure contact part), and the heat generation operation occurs only during that time. During this period, the heating element heats the surrounding circumferential portion due to the heating operation.

In this way, the vicinity of the heating element that generates heat is rapidly heated and the temperature immediately becomes suitable for fixing. For example, when the electrode 237 connected to the heating element 197 in FIG. 3 comes into contact with the first brush 25, the heating element 197 starts generating heat. The heating element 197 continues to generate heat due to the rotation of the heat roller 20 until it reaches the position of the heating element 1912 in the third section, sufficiently heating the surrounding area. Therefore, the temperature of the pressure contact part is brought to a temperature suitable for fixing in such a short time that the heating element at the tip of the first brush 25 comes to the rear end of the first brush 25 when energization is started. be able to. Therefore, warm-up is no longer necessary, and the printing operation can be started immediately upon turning on the power. Moreover, the electricity is applied to each of the 24 heating elements only during the time when the electrode connected to each heating element is in contact with the first brush 25, and the electricity is stopped outside of that time, so in total it takes about 4 minutes. This is equivalent to six heating elements constantly generating heat, and power consumption can be reduced by one unit. Also,
The heating element that has passed through the first brush 25 is naturally cooled down by stopping the current supply, and there is no risk that the temperature of the circumferential surface of the heat roller 20 will rise abnormally.

In the above embodiments, a brush was used as the contact mechanism, but it is needless to say that the present invention is not limited to this.

[Effects of the Invention] As detailed above, the present invention provides a thermal fixing device that can shorten the warm-up time, start the fixing operation quickly after turning on the power, and further reduce power consumption as much as possible. It is possible.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, and FIG. 1 is a diagram showing the configuration of an electrophotographic printer, FIG. 2 is a perspective view showing the configuration of a heat fixing device, and FIG. 3 is a sectional view of a heat roller. . 17... Heat fixing device, 191-1924... Heating element, 20... Heat 0-ra, 21... Pressure roller (member), 2'31-2324...? 25...first brush (contact garden structure), 26...second brush, 2
7...DC power supply.

Claims (2)

[Claims] (1) A heat roller is made up of a plurality of elongated heating elements embedded at predetermined intervals along the axial direction in the circumference, and the heat roller is brought into pressure contact, and the paper to be fixed is forced to pass through the heat roller. a contact mechanism formed so that rotation of the heat roller sequentially contacts a predetermined number of heat generating elements from the front of the pressure contact part to the pressure contact part, and each of the heat generation elements through the contact mechanism. A heat fixing device characterized by being provided with a power source that supplies power to the body. (2) The heat fixing device according to claim 1, wherein a conductive brush is used as the contact mechanism.