JPS61229763A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent to produce wrinkles of sheets when they pass through a fixing roller, by rotating the fixing roller after the forward end of a copy sheet is delivered into a contact of the fixing roller of a fixing device to fix a toner powder image. CONSTITUTION:When a feeding roller 1, a sensitive drum 4, and a delivery belt 5 begin to rotate, a sheet of copy sheets 2 is delivered to a timing roller 3, which begins to rotate synchronously with the sensitive drum 4, and delivered being contacted to the drum 4. The copy sheet 2 copied with a toner powder image is delivered through the delivery belt 5 up to the contact 9 of a fixing roller 8, and made in a form 10a. Since the delivery is continued after the forward end of the sheet reaches the contact 9, the sheet is bent as 10b, and the forward end is aligned against the contact 9. In this moment, the fixing roller 8 is rotated, the copy sheet passes through the contact 9 evenly, and fixation is completed without producing wrinkles.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fixing device such as a copying machine, a fax machine, or a printer. In a fixing device (hereinafter simply referred to as a fixing device) that has =
The rotational operation is performed in synchronization with other rotating bodies in the main body of a copying machine, facsimile machine, etc., which have the fixing device. Therefore, the copy paper is fed into the pressure contact portion of the fixing roller while it is rotating, and is then continuously held and conveyed by the fixing roller.

On the other hand, high heat necessary to melt the toner powder image or high pressure necessary to embed the toner powder image into the gaps between the fibers of the copy paper is applied between the fixing rollers. While the copy paper is being held and conveyed by the fixing rollers, it may expand or shrink slightly due to the effects of temperature and pressure.

For example, if one of the fixing rollers is a Teflon coated roller with a surface temperature of 200C, and the other is a silicone rubber roller, the black and white ratio (hereinafter referred to as black ratio □) is 6% for a character document. When you copy paper, it stretches by approximately 0.s% in the direction perpendicular to the fiber direction of the copy paper, although it depends on the type of copy paper. The copy paper used in this case was freshly opened, but copy paper that has been left indoors for a long time will be affected by humidity, and if it is wetter than the wrapped paper, it will stretch even more. Furthermore, when copying an original with a high black ratio, or to be extreme, an original with full dots, the copy paper tends to shrink.

As described above, when the copy paper is passed through the fixing roller 2, the copy paper expands and contracts, which tends to cause paper wrinkles.

As a countermeasure against paper wrinkles, a method has conventionally been adopted in which an inverted crown is provided on the driving side of the fixing roller. FIG. 2 shows an example. The copy paper 2 conveyed by the fixing drive row 28a provided with an inverted crown has a speed d base i-0 at both end portions that is faster than a traveling speed at the center portion with respect to its traveling direction. This occurs due to the difference in roller diameter between the center portion and both end portions of the fixing drive roller 8a in the axial direction.

Therefore, as the copy paper 2 reaches its end in the traveling direction, a force is generated that stretches the copy paper from the inside to the outside as shown by the arrow CK, which serves to prevent paper wrinkles from occurring.

As yet another example, as shown in Japanese Utility Model Application No. 55-123956, as shown in FIG. A fixing paper guide 7 having a chevron-shaped guide surface higher than both sides is disposed near the fixing roller 8, and as shown in the figure, wrinkles are generated in the paper in the traveling direction d. The fixing paper guide 7 guides the copy paper 2 and forces the part that tends to bend toward the center of the paper by the force e, forcing it upwards as shown in Figure P-3, thereby preventing the occurrence of paper wrinkles. It is something that I try to do.

As described above, the conventional method is extremely effective when the leading edge of the copy paper fed into the pressure contact portion of the fixing roller is aligned with the pressure contact portion. However, in reality, since the rigidity of copy paper is generally low, it is difficult to align the leading edge of the copy paper and feed it into the pressure contact part of the fixing roller, so it is difficult to feed the copy paper to the pressure contact part of the fixing roller, and it is not possible to convey the copy paper while being held by the fixing roller without wrinkles. The current situation is that this is not the case.

Problems to be Solved by the Invention In view of the above-mentioned problems, the present invention provides a method for aligning the leading edge of the copy paper when the copy paper is fed into the pressure contact portion of the fixing roller.
The purpose of this method is to fix a toner powder image onto copy paper using a fixing roller without wrinkling the paper.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is designed to feed the copy paper to the pressure contact portion of the stationary fixing roller.

Function: With the above-described configuration, the leading edge of the copy paper is aligned with the pressure contact portion of the fixing roller, and then when the fixing roller is rotated, the toner powder image is fixed onto the copy paper without wrinkles occurring on the paper. I can do it.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIG. Figure 1 0) is a configuration diagram of the main parts of an electrophotographic copying machine.
(b) The figure is a time chart of the main part, e.)
The figure shows a time chart of the fixing roller in an embodiment of the present invention. In Figure 1 (() 4C, 1 is a paper feed roller provided in the paper feed section, 2 is a copy paper inserted in a paper feed cassette, 4 is a photosensitive drum, 6 is a conveyor belt, and 6 is a fixing device) , 7 is a fixing paper guide, 8 is a fixing roller, and 9 is a pressure contact portion of the fixing roller 8.

The operation of the electrophotographic copying machine configured as described above will be explained. When a copy button (not shown) is pressed, the paper feed roller 1, photosensitive drum 4, conveyor belt 6, and conventionally, the fixing roller 28 start rotating. Paper feed roller 1
As the copy paper 2 rotates, one sheet of copy paper 2 is sent out from the cassette and reaches the timing roller 3. ←) Dotted line 11 in the figure
shows a time chart of the copy paper 2, and 11a indicates the time when the copy paper 2 exactly reaches the timing roller 3.
□After copy paper 2 arrives, wait a while,
The timing roller 3 starts rotating in synchronization with the rotation of the photosensitive drum 4, and sends out the copy paper 2 so as to come into contact with the photosensitive drum 4. The copy paper 2, onto which the toner powder image has been transferred on the photosensitive drum 4, is then conveyed by the conveyor belt 5 and sent to the pressure contact section 9 of the fixing roller 8. (not shown). 10a shows the state of the conventional example at the moment when the copy paper 2 just arrives at the pressure contact portion 9.

6 In the present invention, as shown in FIG. 9, the timing at which the fixing roller 8 is rotated is delayed and brought to a point after the point 11b. That is, at the moment the copy paper 2 is fed into the pressure contact section 9, the fixing roller 8 stops rotating. Since the copy paper 2 continues to be conveyed by the conveyor bell (5) even after its leading edge is thrust into the stationary press-contacting part 9, after a while it becomes bent as shown in FIG. 10b (A). Then, the leading edge of the copy paper 2 is aligned with the pressure contact part 9,
Then (c) when the fixing roller 8 is rotated at the timing of point 12 in the figure, the copy paper 2 uniformly passes through the pressure contact part e,
Therefore, fixing is completed without paper wrinkles.

In addition, as in the conventional example of 8 fixing roller companies, when the copy button is turned on
Even if the rotation starts at the same time) as shown in the figure, point 11b
The rotation may be stopped just before point 11b and restarted at a timing slightly after point 11b.

Effects of the Invention As detailed above, according to the present invention, by stopping the rotation of the fixing roller before the copy paper reaches the pressure contact portion of the fixing roller, the leading edge of the copy paper is aligned with the pressure contact portion, and Fixing can be completed by the fixing roller without causing paper wrinkles.

[Brief explanation of the drawing]

Figures 1 (4) through 1 show one embodiment of the present invention, in which figure (a) is a configuration diagram of the main parts of an electrophotographic copying machine, figure (b) is a time chart of the rotation of the main parts, and , 2) Figure 2 is a time chart of the fixing roller according to the embodiment of the present invention, Figure 2 is a diagram showing the shape of the fixing roller in the conventional example, and Figures 3 (A) to G-1 are the fixing paper in the conventional example. It is an explanatory view showing the shape of a guide. 2...Copy paper, 4...--Photosensitive drum, 2
7...Fixing paper guide, 8...Fixing roller,
9... Pressure welding part. Name of agent: Patent attorney Toshio Nakao
1 Page 2 Figure 3

Claims (2)

[Claims] (1) Copy paper that can carry a toner powder image is fed into the pressure contact section of a pair of rollers, and the pair of rollers pinch and convey the copy paper, and apply pressure and heat to transfer the toner powder image to the copy paper. A fixing device for fixing onto paper, wherein the copy paper is fed into a pressure contact portion of the pair of rollers, and then the pair of rollers are rotated to sandwich and convey the copy paper. A fixing device characterized by: (2) The fixing device according to claim 1, wherein the pair of rollers stops rotating immediately before the copy paper is fed into the pressure contact portion of the pair of rollers.