JPH0331971Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This proposal relates to a hot roller type fixing device used in electrophotographic devices, etc., and in particular to a guide plate for guiding a transfer material between pressure rollers. The present invention relates to a fixing device including:

[Conventional technology]

A heat roller type fixing device is known as a means for heating and fusing an unfixed toner image onto a transfer material in, for example, an electrophotographic device. Such a device is
Typically, it includes a heat roller with a built-in heating source and a pressure roller that is pressed against the heat roller, and a transfer material carrying an unfixed toner image is fed into the nip between the two rollers to transfer the toner image. Fixed on the transfer material. In such a configuration, the toner image is in close contact with the heat roller and directly receives the heat, so it is possible to perform effective fixing with good thermal efficiency. This method has several problems, such as disturbance of the toner image due to blurring of the transfer material when it enters between the rollers. The latter is particularly noticeable when a one-component magnetic toner is used as a developer, and in this case,
The ability of the transfer material to retain the toner is extremely weak, and a slight impact on the transfer material causes the toner image to scatter or become disordered. Therefore, guiding the transfer material between the heated rollers is delicate and difficult. It was hot.

Figure 3 shows a typical heat roller type fixing device.
A guide plate 3 is provided to guide the transfer material to the nip between the heat roller 1 and the pressure roller 2. The guide plate 3 is made of a rigid body whose leading edge 4 extends near the entrance of the nip, and the transfer material is guided along its upper surface. However, in such a configuration,
The tip of the transfer material guided on the guide plate first collides with the circumferential surface of the heat roller 1 (or pressure roller 2), and
Since the toner is then carried into the nip as the roller rotates, it has the disadvantage that the toner image on the transfer material is disturbed by the impact upon collision.

As one of these improvements, for example,
As disclosed in Japanese Patent No. 176077, a guide member has been proposed in which an elastic tongue is brought into contact with the widthwise central portion of the transfer material carrying-in side of the heat roller.

[Problem that the invention attempts to solve]

However, in such a conventional configuration, (1) the tongue piece is configured to rub the circumferential surface of the heat roller, so it scrapes up the silicone oil that is normally applied to the circumferential surface of the heat roller, and the collected oil is used to transfer the image. (2)
Since both ends of the transfer material in the width direction are carried in in a free state, the disturbance of the toner image at both ends remains an inconvenient problem.

The present invention was made in view of the problems with the conventional devices, and aims to provide a heat roller type fixing device with a simple configuration that can eliminate the disturbance of toner images during fixing and obtain an optimal fixed image. purpose.

[Means for solving problems]

That is, in the present invention, a transfer material 30 carrying an unfixed toner image is guided through a guide plate 22 to a nip between a heat roller 11 and a pressure roller 16 arranged above and below, and the heat roller fixes the toner image. This device relates to a mold fixing device, in which a film plate 24 is provided protruding from the tip of a guide plate 22, and the transfer material 3 conveyed from the guide plate 22 by this film body 24 is provided.
The first feature is that the film body 24 has a width that allows the film body 24 to contact almost the entire length of the transfer material 30 in the width direction and guide the transfer material. The tip is arranged so as to be in close or loose contact with the circumferential surface of the pressure roller 16 near the entrance of the nip, and when the transfer material 30 enters the nip, the tip is pressed by the transfer material 30 and the pressure roller 16 The second feature is that it is made of an elastic and heat-resistant plastic material that is flexible so as to come into pressure contact with the circumferential surface of the tube.

[Effect]

With this configuration, when the transfer material is not carried in, the film body is not in contact with the two rollers or is in loose contact with only the pressure roller, so it is not affected by the rotation of the rollers. No load is applied to the roller, and as a result, wear on the roller circumferential surface and the film body tip can be minimized. Moreover, since it is kept out of contact with the heat roller at all times, it is possible to reliably prevent staining of the transfer material due to scraping of silicone oil as in the conventional case.

On the other hand, when the transfer material is carried in, the film body bends due to the pressing force as the transfer material advances and comes into pressure contact with the circumferential surface of the pressure roller, and the transfer material is conveyed along the upper surface of the film body. The transfer material is conveyed along the rollers, minimizing the impact on the transfer material when it enters between the rollers, and preventing scattering and disturbance of the toner image. Further, since the transfer material is conveyed while being supported by the film body over the entire length of the transfer material in the width direction, it is possible to prevent the toner image from being disturbed at both ends of the transfer material as in conventional devices.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, a heat roller, generally indicated by reference numeral 11, has a heating source 12 disposed therein and rotates in the direction indicated by arrow A when in operation. The circumferential surface of the heat roller 11 is made of a material that has good releasability for toner.
For example, it has a Teflon coating, and according to the rotating direction of the peripheral surface, a felt member 13 for applying silicone oil, an adjusting blade 14, and a peeling claw 1.
5 are arranged in sequence. The felt member 13 contains silicone oil from an oil reservoir (not shown) and applies oil to the entire circumferential surface of the heat roller 11, while the adjustment blade 14 applies oil to the circumferential surface of the heat roller 11 over almost the entire length in the width direction of the heat roller 11. Contact them with appropriate pressure to remove excess oil and form a uniform oil layer. The removed excess oil flows along the blade 14 toward one longitudinal end of the blade 14 and is collected into a collection tray via an annular groove (not shown) provided at one end of the heat roller 11.

A pressure roller 16 is disposed below the heat roller 11 so as to be able to cooperate with the roller 11. The pressure roller 16 has its shaft portion rotatably supported by a pair of side plates 17, receives the rotation of the heat roller 11 by a transmission mechanism (not shown), and rotates in the direction of arrow B. One end of the side plate 17 is pivotally supported by a shaft 18, and the other end is biased so as to pivot upwardly by a tension spring 19, thereby causing the pressure roller 16 to move against the heat roller 11. Pressure contact.
The circumferential surface of the pressure roller 16 is made of a heat-resistant elastic material such as silicone rubber. Furthermore, code 2
1 is a peeling claw for peeling off the transfer material.

A guide plate 22 is provided in the nip between the heat roller 11 and the pressure roller 16 as a means for conveying the transfer material. Note that the term "guide plate" is not limited to only a plate shape, but also collectively refers to members of other shapes that guide the transfer material along the upper surface thereof.
The upper end of the guide plate 22 is connected to the rollers 11 and 1.
It is arranged at a position below or approximately equal to, for example, about 10 mm below the tangent line c passing through the contact point of No. 6, and in this example is made of a conductive metal material and is grounded. A tip 23 of the guide plate 22 is appropriately spaced apart from the circumferential surface of the pressure roller 16, and a film body 24 is fixed to the upper surface of the guide plate 22 by adhesive or the like so as to protrude from the tip 23. The film body 24 is a thin piece made of a heat-resistant plastic material with a smooth surface, such as polyamide resin, and has a width sufficient to contact and convey substantially the entire width of the transfer material to be conveyed. Note that "heat resistance" refers to a property that cannot be deformed by heating of the heat roller 11. Tip 2 of film body 24
5 is formed into a substantially straight line, and rollers 11 and 16
It extends so as to be in close or loose contact with the circumferential surface of the pressure roller 16 near the entrance of the nip between the nip, and when the transfer material enters the nip, the tip is pressed by the transfer material and the circumference of the pressure roller 16 is extended. The thickness of the film body 24 is determined to have appropriate flexibility and elasticity so that it can come into pressure contact with the surface almost uniformly. This thickness is preferably, for example, 150 to 300 μm, but is not limited thereto. Further, the free end portion of the film body (the portion not fixed to the guide plate) can have any length, but a good effect was obtained with a length of about 20 mm, for example.

In this way, the transfer material 30 such as paper carrying the unfixed toner image on the upper surface is conveyed by the guide roller 31 along the film body 24 on the upper surface of the guide plate 22 at a speed that is somewhat slower than the conveyance speed by the heat roller 11. As the film body 24 is conveyed and its leading edge approaches the nip between the rollers, the leading edge of the film body 24 comes into contact with the circumferential surface of the pressure roller 16 to form a guide path along the tangential direction of the roller, allowing the transfer material to be flexibly moved between the rollers without impact. Guide it into the nip.

[Effect of idea]

As described above, according to the fixing device according to the present invention, no impact is applied to the transfer material when the transfer material is conveyed to the heat roller, and a high-quality fixed image without image disturbance can be obtained. Moreover, the present invention is very practical because it can be constructed by improving the conventional fixing device as shown in FIG. 3, for example.

[Brief explanation of the drawing]

FIG. 1 is a side view of a heat roller type fixing device according to the present invention, FIG. 2 is a perspective view of a portion of the device shown in FIG. 1, and FIG. 3 is a side view of a conventional fixing device. 11... Heat roller, 16... Pressure roller, 22
... Information board, 24 ... Film body, 30 ... Transfer material.

Claims (1)

[Scope of utility model registration request] In a heat roller type fixing device in which a transfer material carrying an unfixed toner image is guided in a nip between a heat roller and a pressure roller along a guide plate and an elastic film body protruding from the tip thereof, the film body is The tip is arranged near the entrance of the nip so as to be spaced apart from the heat roller and close to or in loose contact with the circumferential surface of the pressure roller, and when the transfer material enters the nip, the tip touches the transfer material. A heat roller type fixing device, characterized in that the heat roller type fixing device is formed so as to be pressed by a peripheral surface of the pressure roller.