JPH03100688A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent wrinkling of paper, jamming, and malfunction of an electrical circuit by providing water drop retaining members which retain water drops in a position on the down stream side of a carrying direction of a fixing means. CONSTITUTION:A recessed and projecting members 12 are formed which are the water drop retaining members retaining the water drops on an inner wall in a vicinity of a paper ejecting opening of a main body exterior 10 in an upper side of a carrying path which is not in contact with a supporting member and in a position on a lower stream side of the carrying direction of the fixing device. These are projections formed 1mm in width and 4mm in height of a same resin as the exterior in a slit state, and the width of the direction vertical to the carrying direction is greater than the width of the passed paper of the fixing device. Therefore, although the moisture evaporated from the supporting member immediately after being passed through the fixing device is frost set by touching the inner wall in the vicinity of the paper ejecting opening, it is retained by the recessed and projecting members 12 and is not dropped inside the machine. Thus, the malfunction of the electrical circuit, wrinkling of paper, and jamming can be prevented.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is used in image forming devices such as electrophotographic devices and electrostatic recording devices, and is used to convey a support material supporting a toner image and fix it by heating. The present invention relates to an image forming apparatus having a fixing means.

[Background technology]

FIG. 6 is a partial sectional view of the vicinity of the fixing device, which is the background art of the present invention. As shown in the figure, the support material supporting the toner image is conveyed to a heat fixing device and fixed thereon, and the heat fixing device has a heat fixing roller 1 and a pressure roller 2 that comes into contact with the heat fixing roller 1 under pressure and rotates as a result. is common. The fixing roller l is made of PTF on the outer circumferential surface of a hollow core metal such as aluminum.
It is coated with a material with good mold releasability such as E or PFA, and a heater such as a halogen lamp is placed inside.
This heats the fixing roller. The temperature of the fixing roller is controlled to about 150°C to 200°C.

The lower pressure roller 2 is made of a metal core made of iron or stainless steel whose outer periphery is coated with an elastic material having mold releasability such as silicone rubber.

Next, the fixation process will be explained.

The support material P, which receives the transfer of the toner image from the surface of the drum as an image carrier by the transfer charger as the transfer means, supports the toner image, and is conveyed to the fixing means passes through the entrance guide 8 and enters the fixing device. The roller enters the nip between the fixing roller 1 and the pressure roller 2, which are rotationally driven in pressure contact with each other, and passes through the nip between the rollers 1 and 2. In the process of passing through this nip, the unfixed toner image ta on the surface of the support material P is permanently fixed to the surface of the transfer material P by the heat of the fixing roller l and the pressing force between the fixing roller 1 and the pressure roller 2. It is then fixed by heat and pressure.

The leading end of the supporting material P which has passed through the nip between rollers 1 and 2 and has had the image fixed thereon is separated from the surface of the fixing roller 1 by a separation claw 5, passes through an exit guide 9, and is delivered to a paper ejection tray (not shown) by a paper ejection roller 11. is discharged to.

[Problem that the invention is trying to solve]

By the way, the apparatus to which the above-mentioned background technology is applied has the following drawbacks.

Support materials such as paper usually contain a large amount of water.

Since the temperature of the fixing roller is normally controlled at about 150°C to 200°C, water vapor is generated from the supporting material immediately after passing through the fixing roller, and before being exhausted to the outside, it is heated to the supporting material at about room temperature in the device. When it touches a non-contact surface, for example, the inner wall 10 of the main body, dew condenses and forms water droplets that adhere to that part. Adhering water droplets can no longer be removed by exhaust air, and the only option is to wait for them to evaporate as the temperature rises inside the machine or dry naturally when the power is turned off.

Therefore, during continuous printing, water droplets accumulate,
The water droplets gradually become larger in diameter, and eventually flow down the inner wall of the main body or fall into the cabin. If these water droplets fall onto electrical circuits, they can cause machine malfunctions, breakdowns, short circuits, etc., which is extremely dangerous. Furthermore, if it falls onto the support material, it will disturb the image, and if moisture adheres to the photoreceptor drum, it will not only disturb the image at that point, but will also cause image smearing and toner fusion on the photoreceptor drum. This causes the occurrence of Furthermore, water droplets on members near the discharge port may cause paper jams, paper wrinkles, or paper jams, and there may be problems such as rusting of the internal parts of the main body and shortening of the service life.

In order to solve the above-mentioned problems, there is a conventional example (Japanese Unexamined Patent Publication No. 1-105978) in which a fibrous sheet is attached as a moisture absorbing member to the paper guide member 9 after passing through the fixing nip.

However, if a moisture absorption member is attached to the paper guide member 9, water droplets can be prevented from falling from the guide member into the inside of the machine, but if only the moisture absorption member attached to the paper guide member is attached, a large amount of water droplets due to condensation will be absorbed as printing continues. When the moisture absorbing member comes into contact with the support material, a problem arises in that the support material becomes wet.

Furthermore, if a moisture absorption member is attached to the guide member, it tends to interfere with paper conveyance, and it is difficult to prevent dew condensation on parts other than the guide member.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides an image forming apparatus having a fixing means for conveying and heat-fixing a supporting material supporting a toner image, in which water droplets are retained at a position downstream of the fixing means in the conveying direction. The present invention is characterized in that a holding member is provided, and an absorbing member that absorbs moisture is provided at a position downstream of the fixing means in the conveyance direction and above the conveyance path. be.

This makes it possible to prevent harmful effects on the inside of the apparatus due to water vapor generated from the support material after passing through the fixing device.

[Embodiment 1] FIG. 1 is a partial sectional view of a device which is a first embodiment to which the present invention is applied. Components that are the same as those in the device shown in FIG. 6 are given the same numbers and will not be described again.

In this embodiment, the location on the downstream side of the fixing device in the conveyance direction! and
A concavo-convex member 12, which is a water droplet retaining member, is formed on the inner wall near the paper discharge port of the external apparatus O above the conveyance path and not in contact with the supporting material.

This has a slit-shaped protrusion with a width of 1 mm and a height of 4 mm made of the same resin as the exterior. The width of the concavo-convex member 12 in the direction perpendicular to the conveying direction is larger than the paper passing width of the fixing device.

In this embodiment, a water droplet retaining member is provided on the outside of the fixing unit that has a pair of fixing rollers, but this is because the interior of the fixing unit is kept at a high temperature by the heat of the fixing roller, so water vapor does not condense. Although this is not a problem, water vapor condenses on the outside of the fixing unit where the temperature is close to room temperature.

FIG. 1 shows 500 sheets of 75 g/rd plain paper continuously printed at a fixing temperature of 150.1 minutes at a speed of 4 sheets in an environment with a room temperature of 22.degree. C. and a humidity of 60%.

Moisture evaporated from the support material immediately after passing through the fixing device touches the inner wall near the paper discharge port and condenses, but it is held by the uneven member 12 and does not fall into the machine. Furthermore, even if continuous printing is continued, water droplets will not fall into the machine. The reason for this is shown in the graph of Figure 2.

FIG. 2 is a graph showing the relationship between the number of sheets printed during continuous printing and the amount of water remaining in the machine in this embodiment. According to this, the amount of water droplets inside the machine due to dew condensation becomes almost constant after about 500 sheets from the start, and does not increase thereafter. This is because at the start, the temperature of the main unit is completely low and the temperature is completely equal to room temperature, so the water that evaporates from the paper after passing through the fixing device tends to turn into water droplets, so the amount of water droplets in the machine increases rapidly, but after printing 500 sheets continuously. By this time, the temperature inside the machine has risen, so the evaporated water is exhausted without turning into water droplets. If the present invention is implemented in this way, no matter how many sheets are printed, water droplets will not fall into the machine.

On the other hand, if the present invention was not carried out, water droplets would fall inside the machine after 200 continuous prints.Furthermore, depending on the vibration of the main body, 100
Even when printing a single sheet, water droplets sometimes fell into the machine. In the present invention, the surface tension of water is effectively utilized by holding condensed water droplets in a thin, dispersed manner using a water droplet holding member having an uneven shape.

Here, FIG. 3 shows a simple model experiment regarding the water droplet retaining ability of the water droplet retaining member. FIG. 3 shows the ability to hold water droplets when water droplets were dropped using a dropper on the parts with and without the water droplet holding member according to the present invention, and the parts were slowly and gently turned upside down. According to this experiment, when the water droplet retaining member was used, the water droplets could be retained even if 20 (4 cry?) water droplets were dropped per 1 crrr. However, when the water droplet retaining member was not used, the water droplets could not be retained even when 5 (lcrrr) water droplets were dropped.

As described above, by carrying out the present invention, the water vapor generated from the paper after the fixing unit and rising can hold the water droplets generated inside the fusing machine, and the ability to prevent water droplets from falling into the fusing machine is dramatically increased. Image disturbances caused by water droplets falling inside the machine, image blurring, toner fusion on the photoreceptor drum, paper jams, paper wrinkles, jams, electrical circuit malfunctions, rust formation inside the sheet and main body, and reduced service life. It can be prevented.

Although the shape of the water droplet retaining member here is a slit-like uneven shape, it is not limited to this shape, and the same effect can be obtained with a lattice-like shape or other uneven shapes.

[Other Examples]

(Embodiment 2) FIG. 4 is a partial sectional view of a device which is a second embodiment of the present invention. The same parts as those in the apparatus shown in FIG. 1 showing the above-mentioned embodiment are given the same numbers, and repeated explanations will be omitted.

In this example, as an absorbent member that absorbs moisture,
Rubicel (manufactured by Toyo Polymer Co., Ltd.), which has good water absorption, is pasted to a thickness of 1 mm on the inner wall of the device exterior cover 1O, which is downstream of the fixing device in the conveyance direction and above the conveyance path. As a result, in this example as well, a high water droplet retention ability was exhibited by utilizing surface tension, and it was possible to prevent water droplets from falling into the machine due to dew condensation, and it was possible to obtain exactly the same effect as the first example. Furthermore, if it is pasted on a portion that is not in contact with the support material as in this embodiment, it will not interfere with the conveyance of the support material, and there will be no paper wrinkles or paper jams, which have been problems in conventional examples. As the moisture absorbing member, not only Rubicel but also fibrous sheets such as nonwoven fabrics with good water absorption properties can be used.

(Embodiment 3) FIG. 5 is a partial cross-sectional view of a device that is a third embodiment of the present invention. The same parts as those in FIG. 1 of the embodiment described above are given the same numbers and will not be described again.

In this embodiment, as a water droplet retaining member for retaining water droplets, hairs with a length of 1 mm are implanted on the inner wall of the apparatus cover 10 on the downstream side in the conveyance direction of the fixing device and above the conveyance path. This also exhibited a high water drop retention ability utilizing surface tension, and the same effect as in the previous example was obtained. Regarding the type of bristles, resin-like bristles, glass-like bristles, and other fibrous bristles can be used.

Furthermore, in this embodiment, the water droplet retaining member is provided only on the inner surface of the device cover above the conveyance path, as in the previous embodiment.
It is more preferable to provide a plurality of water droplet retaining members at other locations as well. It is even more preferable to provide a water droplet retaining member in a portion not in contact with the support material.

〔Effect of the invention〕

As explained above, by attaching a water droplet retaining member or a moisture absorbing member to a position on the downstream side in the conveyance direction of the fuser without contacting the support material, water vapor generated from the support material after passing through the fuser is transferred to the inner wall of the apparatus main body. It disperses water droplets generated by contact and condensation into fine particles and holds them using surface tension.

This prevents water droplets from falling inside the main body or flowing along the inner wall, and prevents image disturbances and blurred images caused by water droplets falling onto the support material, and malfunctions, failures, and short circuits caused by falling onto electrical circuits. , paper jams caused by water droplets adhering to the paper output area, paper wrinkles, paper jams, and rust inside the main unit.
It is possible to prevent a decrease in service life.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment to which the present invention is applied;
The figure is a graph showing the change in the amount of water droplets inside the machine during continuous printing, Figures 3(a) and (b) are diagrams showing the effect of the water droplet retaining member, and Figure 4 is a second embodiment to which the present invention is applied. Figure 5 showing
The figure shows a third embodiment to which the present invention is applied, and FIG. 6 is a diagram showing the background technology that led to the realization of the present invention. l: Fixing roller 2: Pressure roller 3: Heater 4: Temperature control thermistor 5: Separation piece 6: Cleaning felt 7: Fusing unit frame 8: Fusing unit entrance guide 9: Paper ejection guide guide lO2 Bilateral exterior 1: Paper ejection roller 12: uneven member 13: water absorption sheet 14: flocked hanger 1

Claims (9)

[Claims] (1) An image forming apparatus having a fixing means for conveying and heat-fixing a supporting material supporting a toner image, characterized in that a water droplet retaining member for retaining water droplets is provided at a position downstream of the fixing means in the conveying direction. image forming apparatus. (2) The image forming apparatus according to claim 1, wherein the water droplet retaining member is a concavo-convex member having a plurality of concavo-convex portions. (3) The image forming apparatus according to claim 1, wherein the water droplet retaining member is a flocked portion. (4) The image forming apparatus according to any one of claims 1, 2, and 3, wherein the water droplet retaining member is located above the transport path of the support material. (5) The image forming apparatus according to any one of claims 1, 2, and 3, wherein the water droplet retaining member is larger than the maximum sheet passing width of the fixing means. (6) The image forming apparatus according to any one of claims 1, 2, and 3, wherein the fixing means constitutes a fixing unit, and the water droplet retaining member is located outside of the fixing unit. (7) In an image forming apparatus having a fixing means for conveying and heat-fixing a support material supporting a toner image, an absorbing member that absorbs moisture is located downstream of the fixing means in the conveyance direction and above the conveyance path. An image forming apparatus characterized by being provided with. (8) The image forming apparatus according to claim 7, wherein the absorbing member is larger than the maximum sheet passing width of the fixing means. (9) The image forming apparatus according to claim 7, wherein the fixing means constitutes a fixing unit, and the absorbing member is located outside the fixing unit.