JPH0320748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wrinkle prevention device for an image support in a contact heating type fixing device.

Generally, in electrophotographic copying devices, plain paper is often used as an image support, which causes the problem of wrinkles. That is, such a support is normally stored in a cassette and loaded into the device, but since it is hygroscopic and thin, it is easily affected by humidity, and the reason why the tip has wavy irregularities in the width direction is due to This is a common phenomenon. In addition, as a means of transporting the support after transfer to the fixing device, generally a plurality of rotating belts arranged at intervals are used to transport the support while sucking it. It is something that occurs. If such a support having wave-like irregularities in the width direction is inserted into a contact heating type fixing device as it is, wrinkles are likely to occur in the longitudinal direction of the support passing through, which may impair image quality.

Therefore, conventionally, various measures have been taken to reduce the occurrence of such wrinkles from both the device and the support (transfer paper). For example, as shown in FIG. 1, a slit 4 is formed by a guide member 3 between the surface of either one of the heat fixing roller 1 and the pressure roller 2, and the transfer paper 5 is passed through the slit 4 between the rollers 1 and 2. , 2 has been proposed in Japanese Patent Publication No. 53-35731. According to this, the transfer paper 5 once hits the heat fixing roller 1, its leading edge is aligned to some extent, and when the leading edge is nipped between the rollers 1 and 2, the transfer paper 5 hits the leading edge of the guide member 3, so the transfer paper 5 enters the fixing section in a nearly flat shape, thereby reducing the occurrence of wrinkles. However, if the transfer paper 5 whose leading edge is curled or wavy is conveyed under high temperature and high humidity conditions, the transfer paper 5 will not be able to pass through the slit 4 and will stop in front of the fixing section. Further, the transfer paper 5 having a corrugated leading edge cannot be made flat.

Furthermore, as another means, the outer diameter of the center part of the heat fixing roller is several tens of microns smaller than the outer diameter of the end part.
As shown in Japanese Patent Publication No. 55-34430, a roughly drum-shaped metal core with a maximum diameter at the center and a minimum diameter at both ends is coated with a covering layer of an elastic material so that the outer diameter is the same. As shown in Japanese Patent Publication No. 55-47385, paper with a density of 0.65 to 0.72 g/cm ² is used by adjusting the degree of vacuum of the press part suction roll. There are some that are made like this. According to these methods, as shown in Figure 1, wrinkles can be reduced to some extent under normal temperature and normal humidity conditions (20°C, 60%), but if the type of transfer paper changes or Under humid conditions or when the copying speed is increased, wrinkles will occur again.

After all, these conventional techniques can only be expected to be effective to a certain extent when various conditions such as the environment, type of transfer paper, copying speed, etc. are favorable for wrinkles, and when these conditions are unfavorable, This can be said to be a passive countermeasure with little effect.

The present invention has been made in view of these points, and provides a contact heating type fixing device that can reduce the occurrence of wrinkles even when conditions such as the environment, type of transfer paper, and copying speed are unfavorable. The object of the present invention is to obtain a wrinkle prevention device for an image support.

The present invention provides a suction guide member on the inlet side of the support of the heat fixing roller and the pressure roller that suctions the support into close contact with the support in a flat shape and guides the support between both rollers. Therefore, it is configured so that it can be fixed and discharged while preventing the occurrence of wrinkles without being particularly influenced by various conditions.

A first embodiment of the present invention will be described based on FIGS. 2 and 3. First, a heat fixing roller 6 and a pressure roller 7 are provided so as to rotate in the direction of the arrow while facing each other and in contact with each other. A conveyor belt 9 is provided for conveying a transfer paper 8, which serves as a support and has a transferred toner image on its upper surface, toward these rollers 6 and 7. As is well known, this conveyor belt 9 consists of a plurality of belts arranged at intervals, and is supported by rollers 10 and conveys the transfer paper 8 while sucking it using suction means including a suction box 11 and a suction fan 12. It is something.

Therefore, both the rollers 6 and 7 and the conveyor belt 9
A hollow rotary shaft 13 serving as a suction guide member is provided between the two and rotatable in the direction of the arrow. This rotating shaft 13 has a large number of small holes 14 (for example, shaft diameter: 20 mm, small hole diameter: 2
mm, distance between small holes: 2 mm), or as shown in Figure b, a slit 15 (slit width: 2 mm) is formed and connected to the suction means, and the rotating shaft 13
It has suction ability towards the inside of the body. Further, the top of the rotating shaft 13 is set to substantially coincide with a line connecting the contact point between the rollers 6 and 7 and the upper surface of the conveyor belt 9.

In such a configuration, the transfer paper 8 having the transferred toner image is suction-conveyed by the conveyance belt 9 toward the fixing section. Then, the leading end of the transfer paper 8 that has left the conveyor belt 9 is guided by the top of the rotating shaft 13 and advances between the rollers 6 and 7. At this time, since the rotating shaft 13 has a suction ability, Even if the leading edge of the paper 8 is curled or wavy, it is sucked onto this rotating shaft 13 and is forcibly made flat. This action of flattening the transfer paper 8 by the rotating shaft 13 is forcibly performed without being affected by various conditions such as the environment such as temperature and humidity, the type of transfer paper 8, and the copying speed. Of course, the suction force is not strong enough to wrap the transfer paper 8 around the rotating shaft 13. In this way, the transfer paper 8 forcibly made flat by the rotary shaft 13 just before the rollers 6 and 7 is transferred to the rollers 6 and 7.
Since the transfer paper 8 is inserted in between, wrinkles do not occur on the transfer paper 8 after fixing, and the image quality is not impaired.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. The same parts as those shown in the previous embodiment are given the same reference numerals, and the description thereof will be omitted. In this embodiment, when looking at the conveyance state of the transfer paper 8, there is a problem especially near both sides of the transfer paper 8.
In place of the rotating shaft 13, rotating rollers 16 are provided in the passage area near both sides of the transfer paper 8, and a guide plate 17 is simply provided between the rotating rollers 16. That is, this rotating roller 16 functions as a suction guide member, and is formed hollow and connected to suction means, and has small holes 18 formed in its circumferential surface.

Even with such a configuration, when the transfer paper 8 passes the rotating roller 16, both sides thereof touch the rotating roller 16.
6, this rotating roller 16, guide plate 1
Since the sheet is forcibly made into a flat shape on the roller 7 and inserted between the rollers 6 and 7, the occurrence of wrinkles is reduced as in the previous embodiment.

In addition, in these first or second embodiments, as shown in FIG.
It will be more effective if That is, wrinkles can occur if the leading edge of the transfer paper 8 is not nipped by the rollers 6 and 7 at the same time, and skew of the transfer paper 8 is also considered to be a factor. Therefore, the skew correction member 19
rollers 6, 7 and rotating shaft 13 (or rotating roller 1)
6) After performing skew correction of the leading edge of the transfer paper 8 which is provided between the transfer belt 9 and the transfer belt 9,
This is detected by the sensor 20, and the solenoid 21 is operated to lower and retract the skew correction member 19, causing the rotating shaft 13 (or rotating roller 16) to be rotated by suction and inserted between the rollers 6 and 7. . As a result, the transfer paper 8 is made flat and simultaneously nipped between the rollers 6 and 7, so that
The occurrence of wrinkles will be extremely reduced.

Furthermore, a third embodiment of the present invention will be described based on FIG. In this embodiment, instead of providing a separate suction guide member, an extended guide portion 22 is used, which is formed by extending the distal end of the suction box 11 in the suction conveyance device to the side between the rollers 6 and 7. A large number of small holes (not shown) are also formed on the upper surface of the extending guide portion 22.

With this configuration, the leading end of the transfer paper 8 that has left the conveyor belt 9 is sucked onto the extending guide portion 22 and is made flat, and is inserted between the rollers 6 and 7 immediately after it. The appearance of wrinkles is reduced.

In the present invention, as described above, a suction guide member is provided on the support inlet side of the heating fixing roller and the pressure roller to guide the support between the two rollers while suctioning the support into close contact with both rollers. To prevent the occurrence of wrinkles and deterioration of image quality without being affected by various conditions such as the environment, by forcibly making it into a flat state just before reaching the fixing part even if there is a problem with the image. It is something that can be done.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a conventional example, FIG. 2 is a side view showing a first embodiment of the present invention, FIGS. 3 a and b are perspective views of the rotating shaft, and FIG. 4 is a second embodiment of the present invention. 5 is a perspective view of a portion thereof, FIG. 6 is a side view showing a modified example, and FIG. 7 is a side view showing a third embodiment of the present invention. 6... Heat fixing roller, 7... Pressure roller, 8... Transfer paper (support), 13... Rotating shaft (suction guide member), 16... Rotating roller (suction guide member), 22...
Extension guide part (suction guide member).

Claims (1)

[Claims] 1. A support having a toner image is inserted between the pressure bonding portion of a heat fixing roller and a pressure roller that rotates while being in pressure contact with the heat fixing roller, and the toner image is sequentially heat fixed onto the support, and the pair of rollers is In the contact heating type fixing device, a conveyor belt supported by a pair of support rollers and a suction means for sucking the support to the conveyor belt are provided on the support inlet side of the pressure bonding section. Preventing wrinkles on an image support in a contact heating type fixing device, characterized in that a suction guide member is provided between the support roller and the support to bring the support into close contact with the support in a flat shape while guiding the support to the pressure bonding portion between the two rollers. Device.