JPH0473588B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fixing device equipped with a guide body that guides a sheet of paper to a heat roller in, for example, an electrophotographic apparatus or the like.

[Technical background of the invention and its problems]

Heat rollers are often used as fixing devices in electrophotographic devices for safety reasons, but in conventional devices, powder rollers are used to prevent sheet paper from wrinkling during fixing. The sheet paper on which the toner image is to be formed is brought into contact with the upper roller of the heat roller using a flat guide plate that is slightly tilted upward, and the sheet paper is brought into contact with the upper roller of the heat roller to align the leading edges and to give stiffness to the sheet paper A sheet of paper is inserted between the heat rollers while creating a bend.
On the other hand, with the diversification of functions of electrophotographic devices in recent years,
In addition to ordinary sheet paper of about 60 to 70 [g/m ² ] that has been commonly used, there are also small sheets of thick paper of about 200 [g/m ² ], such as those used for postcards and business cards. 40-50 like paper, tracing paper, etc.
There is a need for a device that can form images on sheets of paper as thin as [g/m ² ].

However, in the case of the conventional device mentioned above, 60
In the case of ordinary sheet paper of ~70 [g/m ² ], it is given a moderate stiffness, and even if the sheet paper is stretched somewhat between the heat rollers due to variations in the rotation speed of the heat roller in the width direction, etc. Fixing can be performed reliably without wrinkles, etc. However, in the case of thick sheet paper, it is difficult to cause sagging, and the leading edge of the sheet paper may remain stationary in contact with the upper roller, or the paper may not be fed properly. This has the disadvantage that the paper is forcefully fed by the paper roller and runs onto the upper roller, resulting in a paper jam. For this reason, if the guide plate is made almost parallel and the leading edge of the sheet paper is inserted directly between the heat rollers, this problem can occur even with ordinary sheet paper, but especially with thin sheet paper, because the sheet paper is particularly weak. , even if the sheet paper is slightly distorted when it is inserted between the heat rollers, wrinkles will occur immediately and the sheet paper will be damaged.
This poses a new problem of unusability, and has hindered the realization of an apparatus that can form images on everything from thick sheets to thin sheets.

[Purpose of the invention]

This invention was made based on the above circumstances, and uses a fixing device consisting of rollers such as heat rollers to handle sheets of paper from thick to thin without damaging the paper or making it impossible to convey the paper.
It is an object of the present invention to provide a fixing device that can perform fixing reliably.

[Summary of the invention]

This invention forms steps on the guide plate and changes the angle of approach to the fixing roller depending on the thickness of the sheet paper, thereby preventing wrinkles or poor conveyance of the sheet paper, regardless of the thickness of the sheet paper. This is to ensure that fixing is carried out without any problems occurring, thereby improving the reliability of the apparatus.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. An upper roller 11a, which is a first roller that has a built-in heater 10 and is an aluminum roller coated with Teflon (registered trademark), and a lower roller 11b, which is a second roller made of silicone rubber.
A guide plate 13, which is a guide body, is provided in front of the heat roller 11, which is a pair of rollers made up of the following. The guide plate 13 has a first approach angle, a first guide portion 13a that is a first guide surface with a width that allows a postcard-sized sheet to pass through, and two sides of the first guide portion 13a. A second guide portion 1 which is a second guide surface provided at a second approach angle and has a second approach angle.
3a, and further includes a first guide portion 13a and a second guide portion 13a.
A regulating guide 13c, which serves as a regulating means and is parallel to the traveling direction of the sheet paper, is provided between the guide portion 13b and the guide portion 13b, and closes the step. The first guide portion 13a controls both sides or one side by a regulating guide 13c so that the thick sheet paper 12a, which is about the size of a postcard or business card and has a weight of about 200 [g/m ² ], is brought into contact with the lower roller 11b. The second guide part 13b mainly uses ordinary sheet paper 12b of about 60 to 70 [g/m ² ] of general sizes such as [A.4] and [B.4] size, or about 40 to 50 g/m2. [g/m ² ] thin sheet paper 12c or the like is guided so as to come into contact with the upper roller 11a.

However, when copying using the thick sheet paper 12a is started, an image forming apparatus (not shown)
The thick sheet paper 12a on which the powder toner image is formed is conveyed by a conveyance device (not shown) and reaches the guide plate 13. At this time, since the thick sheet paper 12a is small-sized such as a postcard or a business card, the second guide portion 13b
It falls into the first guide part 13a at the center of the guide plate 13 without extending into the first guide part 13a.
The lower roller 11b is supported by the lower roller 11b while being regulated on both sides or one side by the regulating guide 13c. As a result, the thick sheet paper 12a is placed on the heat roller 1 with its leading edge placed on the lower roller 11b.
1, and is inserted and fixed, and the copying process is completed. Next, copying using ordinary sheet paper 12b or thin sheet paper 12c will be described. An ordinary sheet paper 12b or a thin sheet paper 12c on which a powder toner image is formed by an image forming device (not shown) is conveyed to a conveying device (not shown) and reaches a guide plate 13. At this time, since the normal sheet paper 12b or the thin sheet paper 12c is of a general size, it does not fall onto the first guide section 13a, and both sides are moved to the second guide section 13b.
The upper roller 11a contacts the upper roller 11a. With this, the normal sheet paper 12b or the thin sheet paper 12c is aligned, and then the guide plate 13
A deflection is formed between the upper roller 11a and the upper roller 11a, and the sheet is guided between the heat rollers 11 while being given stiffness, and is inserted and fixed to complete the copying.

Furthermore, in rare cases, ordinary sheet paper or thin sheet paper with a narrow width is used, but such a paper may be dropped onto the first guide portion 13a without being given any stiffness. Also, since it is small, there is little distortion during passing between the heat rollers 11, and wrinkles are less likely to form.Furthermore, even if wrinkles are formed, they tend to come off to the outside, so that there is little influence on image quality and no inconvenience occurs.
Also, there are cases where a thick sheet paper of a wide normal size is used and guided to the upper roller 11a side by the second guide portion 13b, but in this case, compared to the small thick sheet paper 12a, Since the tip easily bends due to its weight, it is possible to pass it to the heat roller 11.

With this configuration, even though the guide plate 13 is integrally formed, the thick sheet paper 12
In the case of paper a, it can be easily inserted between the heat rollers 11 without causing paper jams, and fixing can be performed reliably, while in the case of ordinary sheet paper 12b or thin sheet paper 12c, while passing between the heat rollers 11, Each sheet paper 12b, 12c can be given stiffness, and each sheet paper 12b, 12c can be slightly distorted.
wrinkles can be prevented and high-quality copied images can be obtained. In addition, since the level difference between the first guide part 13a and the second guide part 13b is closed by the regulation guide 13c, the small sheet paper does not advance while being supported by the first guide part 13a. There is no risk of misalignment or falling from the gap, and the reliability of the device can also be improved.

Note that this invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, the inclination angle and width of the first guide part and the second guide part can be arbitrarily determined depending on the characteristics of each sheet of paper. However, the second guide part needs to be set at an inclination suitable for both normal sheet paper and thin sheet paper. Furthermore, the shape of the guide plate 13 is also arbitrary, and as in another modification shown in FIG.
a is used as the first guide part, and its side parts 16b are used as the second guide parts, or an auxiliary guide (not shown) made of a leaf spring or the like is provided in the notch part 16a in the center, so that thick sheets of paper can pass through. At times, the auxiliary guide may escape so that the sheet paper comes into contact with the lower roller. Further, the thickness and shape of each sheet of paper are not limited, and the thick sheet of paper may be a book card or the like as long as it is within the width of the first guide portion.
Further, the roller may also be a mere pressure roller instead of a heat roller.

〔Effect of the invention〕

As explained above, according to the present invention, since the thick sheet paper is mainly small in size, up to the size of a postcard, the integrated guide plate includes a first guide surface having a narrow width and a portion above the first guide surface. The second inclined to
A thick sheet of paper falls into the first guide surface and enters into contact with the lower roller, while a normal or thin sheet of paper is allowed to fall into the first guide surface and contact the upper roller. By allowing the paper to enter the rollers so that they are in contact with each other, thick sheets of paper can be easily passed between the rollers without jamming, while ordinary or thin sheets of paper can be prevented from wrinkling while passing between the rollers. , regardless of the thickness of the sheet paper, it is possible to perform fixing reliably, and the reliability of the apparatus can be improved.

In addition, as in the embodiment, the first and second
By closing the step between the first guide surface and the first guide surface, the sheet paper passing through the first guide surface is regulated by its side surfaces, and there is no risk of it shifting or falling through the gap, further improving the reliability of the apparatus.

[Brief explanation of drawings]

1 and 2 show one embodiment of this invention, FIG. 1 is a schematic sectional view thereof, FIG. 2 is a perspective view thereof, and FIG. 3 is a perspective view showing another modification of this invention. be. 10... Heater, 11... Heat roller, 11
a...Upper roller, 11b...Lower roller, 12a...
...Thick sheet paper, 12b... Ordinary sheet paper, 1
2c...Thin sheet paper, 13...Guide plate, 13
a...first guide part, 13b...second guide part, 16...guide plate, 16a...notch part, 1
6b...Both sides.

Claims (1)

[Scope of Claims] 1. In an apparatus for fixing an image by inserting an image support between a pair of rollers consisting of a first roller and a second roller that rolls into contact with the first roller, the first and second rollers are fixed. a first guide surface for guiding the image support to exhibit a first approach angle with respect to the pair of rollers; and a second guide surface for guiding the image support to exhibit a second approach angle different from the first approach angle.
and a step difference between the first guide surface and the second guide surface, and restrict both ends parallel to the traveling direction of the image support guided by the first guide surface. A fixing device comprising a guide body comprising a regulating means and guiding the image support between the rollers at different angles of approach depending on the stiffness of the image support. 2. The first approach angle is the angle at which the image support is brought into contact with the second roller, and the second approach angle is the angle at which the image support is brought into contact with the first roller. The fixing device according to scope 1. 3. The fixing device according to claim 1 or 2, wherein the guide body guides the image support according to the size of the image support using the first guide surface and the second guide surface, respectively. .