JPS6019512B2 - Fusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for an electrophotographic copying machine, particularly one using a heating roller and a pressure roller.

In this type of fixing device, it is desirable to apply an anti-offset liquid to the heating roller in order to prevent toner from adhering to the heating roller and copy paper from wrapping around the heating roller.

However, when the anti-offset liquid transfers to the pressure roller, it causes the roller to swell and causes uneven fixing. The present invention aims to solve this problem.

As a means for this purpose, since the transfer of the liquid to the pressure roller is unavoidable, the object of the present invention is to simply and cleverly obtain a device that can reliably strip off the transferred material. A specific example of application of the present invention to an example of a fixing device will be described below in relation to the entire device.

Reference numeral 1 denotes a copying drum, which is arranged sequentially in the circumferential direction and has a toner image formed on its surface by various well-known means such as charging, exposure, and development (not shown in the figure), and is rotated to the transfer position shown in the first figure. do.

Copy paper P sent from a cassette (not shown) is sent toward the copy drum 1 via guides 30A and 3B synchronously with respect to the toner image by timing rollers 2A and 2B, and is driven by the action of a contact charger 4, etc. The toner image is transferred onto the copy paper P while it is in close contact with the drum surface and separated at the same speed by the separation roller 5, separation guide 6, and auxiliary rollers 7A and 7B. After the copy paper that has come out of the separation rollers 5 and 78 is neutralized by the corona action of the charger 8, it is transferred to the heating roller 11 via the guide 9 and guide plate 10, each having a comb-shaped cross section.
- The toner image is sent between the pressure rollers 12 and fixed by heat, and is guided by the claw-shaped guides 13A and 13B to the discharge roller 1.
4A and 14B, it is sent out from the discharge port 15.

FIG. 2 shows the drive system built into the back side of the side plate 16A viewed from the opposite side of FIG. The heating roller 11 on the same axis 16 as G6 is rotated.

The pressure roller 12 follows the heating roller 11. Furthermore, G6
, the shafts 17A and 17B of the discharge rollers 14A and 14B are driven through G8 to GIO. G7 is pressure roller 1, which will be described later.
This is the gear for driving the pressure release mechanism No. 2. Guide 3A above
, 3B, separation rollers 5, 7A, 7B to discharge roller 14
Each member up to A and 14B is the front and rear side plate 1 in FIG.
6 and 16A (FIG. 4) to form a transfer/fixing section unit U.

Raise the lock fitting 18 shown in FIG. 1 provided on the main body of the copying machine to release the lock pin 19, and then tilt the unit U counterclockwise around the support shaft 20 as shown by the chain line in FIGS. 5 and 6. Each member of the transfer section 3A, 3B, separation belt 21, separation roller 5,
7A has a large distance from the photosensitive drum, making it easy to remove jammed paper in the transfer section and perform other inspections and repairs.
The guide 38 can be opened widely with respect to the shaft 3A against the spring 3D around the axis 3C. Auxiliary side plates 22 and 22A (FIG. 7) are attached to the side plates 16 and 16A with shafts 23, and between the auxiliary side plates there is a heating roller 11, an upper lid 24, a pull-out type machining roller cleaner 25 on the lower surface of the upper lid, and a roller temperature detection element 26.
Assemble etc. Pull the front and rear locking fittings 27, 27A against the spring, remove them from the engagement holes 28 of the side plates, and remove the auxiliary side plates 22.
, 22A are raised around the shaft 23 as shown in FIG. 7 to widen the space between the two rollers 11 and 12, so that jam removal and other operations can be performed freely regardless of the high temperature of the fixing section. shall be. The heating roller 1 that is the object of the present invention is a metal cylinder whose surface is coated with release rubber such as Teflon or silicone rubber or other effective materials to a thickness of about 0.3 mm, and has a heating element inside. It is housed and kept at a surface temperature of about 180 pm.
The pressure roller 12 is an elastic roller whose surface is made of rubber.
When the copy paper P is sandwiched between the rollers 11 and 12 during fixing, it is slightly depressed to form a nip.

The heating roller 11 is coated with an anti-offset liquid C such as silicone oil in order to prevent toner from adhering and copy paper from wrapping around the heating roller 11 .

The anti-offset liquid is stored in a dish 30' in FIG. 1, and when it is consumed below the set liquid level, the float valve 31 operates to open the valve port 32 and replenish from the tank 33 to maintain a constant liquid level.

The lower end 35A bent at right angles of a coating material 35 having capillary action such as felt attached to the holder 34 is immersed in the liquid level, and the upper part is brought into contact with the heating roller 1 for coating. heating roller 1
1 has a liquid-resistant coating such as Teflon as described above, but since the pressure roller 12 is a rubber loaf, it absorbs the coating liquid,
It swells approximately in proportion to the amount of absorption.

Generally, copying machines are sized to accommodate several paper sizes.
For example, as shown in FIG. 8, when A4 and B slopes are used, during temporary copying of A4 and B, the coating liquid in the A4 surface of the heated loaf surface is absorbed by the copying paper, so there is very little adhesion to the pressure roller 12. However, in the area where there is a difference L from the B4 plate, almost all of the coating liquid on the heating roller 1 adheres to the pressure roller 2, and that area gradually swells to form a step LI as shown in FIG. 8L. The stage LI pushes the A4 paperboard towards the inside, causing wrinkles.
Thereafter, when copying onto B4 size paper, uneven pressure bonding and therefore uneven fixing occur due to the stage LI. Furthermore, the coating liquid adhering to the L portion stains the back of the paper. Therefore, in the present invention, as shown in FIG. 9, the tip of a scraper or scraping plate 36 made of a thin metal spring material such as phosphor bronze or stainless steel or an elastic material such as urethane rubber is provided in contact with the surface immediately below the pressure roller 12. The coating liquid is scraped off at a position approximately half a turn away from the pressurizing part for the copy paper, and is collected into a container 39 through a reservoir pipe 38 in a lower tray 37 along the plate surface.

Since the amount of scraping is not so large, a signal may be issued every time a certain number of copies of A4 size paper are made, and the plate 37 may be pulled out and treated. At the end of the copying operation, the applicator 35 rotates clockwise about the shaft 55 by a known method and separates from the heating roller 11, so that the copy paper P is coated in the loaf 11,1.
2, the rollers 11 and 12 at least maintain the pressure between the liquid application position and the contact position of the rollers 11 and 12 with respect to the rotation direction of the heating roller from the time when the coating material 35 separates from the heating roller 11. The sum of the length of the roller circumferential surface and the length between the contact position of rollers 1 and 12 and the scraping support position in the rotational direction of the pressure roller is 1 or more, and the anti-offset liquid transferred to the elastic loaf is completely rotated. The drive is controlled so that it stops after being stripped. The scraping plate 36 may be brought into pressure contact by its own elasticity, or another spring may be added to bring it into elastic contact.

With the above configuration, from the heating roller 1 to the pressure roller 2
The anti-offset liquid transferred to is stripped off every rotation.

Therefore, it is possible to eliminate the drawback that the toner swells during fixing, causing uneven fixing and deteriorating the quality of copies. Furthermore, while the copying operation is stopped after copying is completed, the elastic roller is prevented from swelling due to the anti-offset liquid, thereby preventing uneven fixing, and constant and stable fixing can be performed at all times.

[Brief explanation of the drawing]

The drawings illustrate a fixing device to which the present invention is applied, and FIG. 1 is a front view of the fixing device unit with the front side plate removed;
Figure 2 is a front view of the opposite side of the unit, Figure 3 is a front view of the front side, Figure 4 is an enlarged cross-sectional view of the unit side plate and part of the drive mechanism, and Figures 5 and 6 are head movement of the unit. An explanatory diagram, FIG. 7 is a diagram of the heating roller block in an upright state, and FIG. 8 is a perspective view showing the relationship between the heating roller/fixing roller and copy paper size.
9 and 10 are front views of the offset prevention liquid scraping section. 1 is a photoreceptor, U is a fixing device unit, 11 is a heating roller, 12 is a pressure roller, 13A, 13B are guide claws, 34
36 is an offset prevention liquid coating material, 36 is an offset prevention liquid peeling member, 37 to 39 are collection containers, and 41 is an auxiliary peeling member. Figure 2 Figure 2 Figure 4 Figure Tsutomu 7 Figure 5 Resurrection Figure Kizaku Gu Zu Zuko Ku Figure Grandson '0 Figure

Claims (1)

[Claims] 1. Means for passing copy paper carrying a toner image between a pair of rollers, heating to keep a heating roller rotating in contact with the surface of the copy paper bearing the toner image of the pair of rollers at a temperature higher than the toner melting point. means, an elastic roller that rotates in contact with the surface of the copy paper that does not have a toner image, a means for applying anti-offset liquid to the heating roller, a scraper for stripping off the anti-offset liquid transferred to the elastic roller, and a scraper for removing the anti-offset liquid transferred to the elastic roller. It has a means for recovering the anti-offset liquid, which separates the application means from the heating roller when the copying operation is stopped, and at least maintains a distance between the anti-offset liquid application position and the contact position of the pair of rollers with respect to the rotational direction of the heating roller. Rotate the pair of rollers by a length equal to or longer than the sum of the length of the circumferential surface of the heating roller and the length of the circumferential surface of the elastic roller between the contact position of the pair of rollers and the scraper contact position with respect to the rotational direction of the elastic roller. A fixing device characterized in that both rollers are stopped after being fixed.