JPH0128524Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device that has first and second rotating bodies and fixes the image by passing a support material supporting a toner image through the rotating bodies.

Conventionally, when fixing a toner image, a pressure fixing method using only pressure, or a heat fixing method in which the toner image is melted and fixed using heat and pressure are often used. In these cases, the degree of pressure applied to the toner image has a large influence on the image, particularly when a pressure fixing method is used. An image forming apparatus using the pressure fixing method will be described in detail below.

FIGS. 1A and 1B, 2A and 2B, and 3A and 3B each show a conventional pressure fixing device.

In FIGS. 1a and 1b, the press roll 1 and the main roll 2 are connected to the fulcrum 7 by side plates 3, 4, 5, and 6 on the same side, which are separated from each other.
Bolts 8, 9 and springs 8 ₁ connected to 4, 5, 6,
9 compressed by ₁ . According to this configuration,
If the springs 8 ₁ and 9 ₁ are placed farther away from the rolls 1 and 2, weaker springs can be used, and there is an advantage that the change in spring load due to the thickness of the paper supporting the toner will be reduced. ₁ and 9 ₁ are located on both sides of the roll, which has the disadvantage of increasing the size and total weight of the device.

In addition, the ones in Figure 2 a and b are main roll 1
Main roll 1 consists of three rolls: 1, bottom roll 12, and press roll 13, which intersect with each other.
The toner on the paper that has passed between the roller 1 and the bottom roll 12 is fixed. The main roll 11 is fixed to fixed frames 14 and 15, and the bottom roll 12 and press roll 13 are attached to separate side plates 16, 17, 18, and 19, respectively.
It is configured to be able to move up and down along guide surfaces in the recesses of the frames 14 and 15.

Furthermore, springs 10 and 10 ₁ are provided at the lower portions of the side plates 17 and 19 of the press roll 13, thereby applying a pressing force to the rolls 11, 12 and 13.

This configuration has the advantage of being able to solve the problem of increasing the size of the device, which was the problem in FIGS. However, in this method, each side plate needs to move independently along the guide surface in the recess as the paper enters, so it is necessary to increase the distance from the frames 14 and 15 to some extent. This causes fluctuations in the intersection angle between the main roll 11 and the bottom roll 12, resulting in uneven fixing and wrinkles on the paper due to pressure differences on the toner image and paper and fluctuations in the roll 12. Something happened.

Further, FIGS. 3a and 3b show a so-called one-sided reference case which solves the drawbacks of conveying the paper S using the center reference using the apparatus shown in FIGS. 1a and 1b.

As shown in Figure 3a, in a copying machine based on one side,
Regardless of the copy size, in other words, regardless of the total width S ₁ and S ₂ used, one side edge L in the width direction must be substantially aligned with one common reference line. The carrier is configured to transport the support material.

With this configuration, there is no need to align the center line in the width direction of the paper with the center line in the longitudinal direction of the rolls 1 and 2, and in the case of a transfer type copying machine, there is no need to further align the center line in the photoreceptor. A simpler and cheaper device is obtained than central transport which requires a mechanism.

However, especially when using this configuration with one-sided reference, when fixing a small width paper S ₁ , toner image fixation on the transport reference line side will be poor, and the area on the opposite side of the paper from the reference line side will deteriorate. When an overload is applied to the paper, problems occur such that the paper surface becomes glossy, the paper becomes thinner and becomes transparent, or it is destroyed to pieces. As shown in Fig. 3b, the roller 1 has an equal load W ₁ applied to both ends.
When the paper S is clamped between the rollers 2 and 2, the vicinity of the side edge P' of the toner image carrier S on the side opposite to the conveyance reference side edge P supports the load between the rollers where there is no paper on the right side. It is. This is also because the roller 1 rotates slightly clockwise about this edge P' as a fulcrum, and the pressure applied to the paper on the side edge P decreases. This inconvenience arises especially when rollers 1 and 2, or one of them, is a highly rigid roller with hard chrome plating applied to the circumferential surface of the steel roller, and the amount of elastic deformation is very small. This is especially serious in such cases. Of course, there is a similar tendency in central conveyance copying machines.

The present invention was devised to solve the above-mentioned problems, and has a high degree of fixing performance regardless of the conveyance state of the toner image support material, facilitates paper entry, and prevents wrinkles. It is an object of the present invention to provide an image forming apparatus that is highly preventive and has a compact fixing section.

In order to solve the inconveniences in the conventional structure, the present invention has first and second rotating bodies, and a supporting material supporting a toner image is passed between the pair of rotating bodies to fix the toner image on the supporting material. In the image forming apparatus, a flange that integrally holds a first rotating body rotatably at both ends thereof and is movable or rotatable about a fulcrum, and a stay that integrates the flanges at both ends of the first rotating body. , a pressurizing means for pressurizing the flange of the first rotating body to press the first rotating body toward the second rotating body; It is characterized by integrally displacing one rotating body.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIGS. 4a and 4b are a sectional view and a perspective view, respectively, of essential parts of an embodiment of the present invention. For example, in an electrophotographic process, a latent image corresponding to an original is formed on a photoreceptor by optical means, and the latent image is converted into a toner image by developing means, which is then transferred to a support material such as paper (not shown). ). The support material S supporting the toner image is guided in the direction of the arrow in the figure by a conveying means or the like (not shown).

In the figure, 22 is a main roll driven by a desired driving means, and stays 34, 35,
Frames 32 and 33 fixed by 36 and 37 are rotatably supported at fixed positions. A press roll 21 is rotatably supported by side plates 23 and 24. These side plates 23 and 24 are connected to the frame 3
2 and 33 in a non-contact manner. The pins 26 and 27 that are removably fitted into the frames 32 and 33 are connected to the holes 26 of the side plates 23 and 24.
₁ , 23 ₂ , the side plates 23 , 24 can slide relative to the pins 26 , 27 .
It is designed to be able to rotate using the fulcrum as a fulcrum. Further, a stay 25 is coupled to the ends of the side plates 23 and 24, thereby integrating the side plates 23 and 24. Further, springs 28,
29 is fixed, and the press roll 21 is pressed against the main roll 22 by compressing the springs 28 and 29 using screws 30 and 31 that come out through tapped holes in the frames 32 and 33. is driven to rotate. This spring 28,
The compressive force applied by 29 is of a magnitude that causes the toner image to be fixed under pressure.

Further, the springs 28 and 29 are located on the center line of the press roll 21, and the side plates 23 and 24 and the stay 25 are almost completely rigid bodies. Press roll 21
pins 26 and 27 each time the paper S enters and exits.
It can move up and down or rotate using the fulcrum as a fulcrum.

Figures 5a and 5b are top views of an embodiment in which the paper S enters the apparatus having the configuration shown in Figure 4, and Figure 5c is a schematic side view of the embodiment during entry. It is something.

In FIG. 5a, the paper S supporting the toner image is fed diagonally between the rolls 21 and 22,
FIG. 5b shows a case in which a small-sized paper S ₂ is entered by being conveyed on one side. If these conveyance methods were applied to the conventional device, the result would be as shown in FIG. 3b, as described above, and the springs 8 on both sides of the press rolls 1 and
There were drawbacks such as either one of ₁ or 9 ₁ not working.

On the other hand, in this embodiment, when the paper S enters, the entire press roll is moved in parallel both at the entry point P and in the gap P'' on the opposite side, as shown in FIG. 5c. A force in the lifting direction is applied to facilitate the entry of the paper S, and an excellent wrinkle prevention effect is achieved.

With the above configuration, the left and right springs 28, 2
The case where only one of 9 is activated is completely eliminated, and at least the balance between the left and right pressurized states can be stabilized to a higher degree, and excellent fixing performance can be achieved.

In the above embodiment, an image forming apparatus for an electrophotographic process is used in which conveyance is performed on one side. However, the present invention is not limited thereto, and is also effective in a desired image forming method, central conveyance, etc. However, it is extremely effective in double-sided copying, etc. Further, in the above embodiment, the main roll 22 and the press roll 21 are arranged parallel to each other, but in the present invention, the main roll 22 and the press roll 21 are arranged in a crossed manner.
Needless to say, it is particularly effective in the case of

In contrast to the arrangement in which the rolls 22 and 21 cross each other, the flanges 23 and 24 and the stay 25 are integrated to move the press roll 21 to the main roll 22.
Specifically, when the stay 25 is not present, the cross arrangement of the rolls 22 and 21 causes a large load on the flanges 23 and 24, and as described above, the load between the rolls increases. This can solve the problem of worsening pressure distribution.

Furthermore, although the above embodiments have been explained in the case of pressure fixing, the present invention can also be applied to the case of combining heat fixing and pressure, where pressure affects the degree of fixing.
It has a similar effect of improving fixing performance.

Moreover, the side plates 23, 24 and the stay 25 of the above embodiment
The press roll 21 is made rotatable by being integrated with the pins 26 and 2 as fulcrums.
7, but the present invention includes those in which the side plates 23, 24 and the stay 25 are integrally manufactured with one rigid body such as a metal, and in which the side plates 23, 24 and the stay 25 are integrally manufactured with a rigid body such as a metal, and the other end of the press roll is quickly responded to a change in the other end of the press roll. Any device can be used as long as it stabilizes the balance with respect to the main roll, and the side plates 23 and 24 can be rotated almost stably by using rotating shafts or elastic bodies instead of the pins 26 and 27. Various types of holding devices can be used, and the fulcrum may be moved in any direction, up, down, left, or right.

Furthermore, it is also an extremely preferable embodiment to use the configuration used for the press roll 21 for the main roll 22.

As described above, the present invention can be applied to a conventional image forming apparatus,
In particular, it solves the drawbacks of image forming apparatuses that use pressure fixing, and is able to highly prevent the occurrence of wrinkles on the support material, regardless of the conveyance state of the toner image support material or the thickness of the support material. This largely prevents partial overload of the rotating body that causes fixing blur and light conditions, achieves a higher and more uniform pressure distribution, and achieves a higher fixing effect.

[Brief explanation of the drawing]

Figures 1a and 1b are a perspective view and a side view of a conventional single-pressure fixing device, respectively, and Figures 2a and 2b are
are perspective views of other conventional pressure fixing devices, respectively;
In the side view, FIGS. 3a and 3b are a perspective view and a schematic diagram of another conventional one-pressure fixing device, respectively.
Figures a and 4b are a cross-sectional view and a perspective view of essential parts of an embodiment of the present invention, respectively, and Figures 5a and 5b are top views showing the approach of paper in an embodiment of the present invention, respectively. Figure 5c is a schematic side view of an embodiment of the present invention when it is held. 21 is a press roll, 22 is a main roll, 2
3 and 24 are side plates, 25 is a stay, 26 and 27 are pins, 28 and 29 are springs, 30 and 31 are screws, 3
2 and 33 are frames, 23 ₁ and 24 ₁ are holes, and S is paper.

Claims (1)

[Claims for Utility Model Registration] (1) In a fixing device that has first and second rotating bodies and fixes the toner image on the supporting material by passing a supporting material supporting a toner image between the pair of rotating bodies. , a side plate that rotatably integrally supports the first rotating body at each end and is movable or rotatable about a fulcrum; a stay that integrates the side plates at both ends of the first rotating body; and a second rotating body. a fixed support member that rotatably supports the body at a fixed position; and a pressurizing means that presses a side plate of the first rotating body to press the first rotating body toward the second rotating body, With respect to the second rotating body, the side plate, the stay,
A fixing device characterized in that a first rotating body is integrally displaced. (2) The fixing device according to claim 1, wherein the first and second rotating bodies are toner image pressure fixing rolls arranged crosswise to each other.