JPS6049308B2 - Fusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a device for fixing a powder image on a carrier, in particular a fixing roller to which the powder image bearing surface of the carrier is brought into pressure contact, and an anti-offset liquid is applied to this roller. The present invention relates to a fixing device adapted to perform coating.

In the field of electrophotography, after forming an electrostatic latent image on a photoreceptor,
The latent image is developed using a suitably polarized toner, that is, a colored powder whose main component is a thermosoluble synthetic resin.

The toner image formed by this developing step is fixed on the photoreceptor as it is, or is transferred to plain paper or the like and then fixed there. There are various types of devices for fixing toner images on their carriers, but one example is a fixing roller whose surface is heated to a temperature that can melt the toner using an internal or external heat source, and a fixing roller that uses paper, etc. An example of a fixing device includes a pressure roller that presses the toner image bearing member. In this apparatus, both the fixing and pressing rollers are rotated to cause the carrier to pass through the nip formed by the rollers, thereby fixing the carrier from one end to the other. The toner image bearing surface of the carrier is brought into pressure contact with a fixing roller. Here, on the fixing roller,
It is known to apply an anti-offset liquid such as silicone oil to prevent heated and molten toner from adhering. If the molten toner adheres to the fixing roller, the next time it comes into contact with the carrier, it will adhere to the carrier and stain it. On the other hand, when the carrier is sent out from the nip as the two rollers rotate, it tends to be conveyed while remaining in close contact with the fixing roller. In other words, the carrier tends to wrap around the fusing roller. Therefore, in order to send the carrier after the fixing process to a conveyance path to a place such as a storage section, a means is required to peel off the carrier from the fixing roller as it comes out of the nip while remaining in close contact with the fixing roller. Become. For this purpose, a claw-like separating member is arranged so that its tip contacts the fixing roller, thereby separating the carrier in close contact with the fixing roller from this roller, and moving the carrier into a predetermined conveyance path. It is designed to guide and guide. By the way, since the tip of the separating member is in contact with the fixing roller as described above, the separating member scrapes off the offset prevention liquid applied to the fixing roller. When this accumulates on the separating member, it adheres to the carrier and forms a perforation-like stain.
However, when fixing a carrier of a certain size, and when fixing new carriers one after another almost continuously, the separation member that peels off the carrier from the roller is difficult to fix. Part of the anti-offset liquid applied to the roller is taken away by the carrier one after another, so the amount of liquid scraped off by the separation member is relatively small, and the liquid that is scraped off is collected on the separation member before it accumulates in a large amount. The anti-offset liquid is carried away by the sliding carrier one after another, so even if the anti-offset liquid scraped off by the separation member adheres to the carrier of the size currently fixed, it is hardly a stain. ``It's not noticeable.

However, during the fixing process for a carrier of a certain size, there is a separation member provided at a position where the carrier does not come into contact with the carrier, that is, a separation member for separating carriers of other sizes from the roller. A relatively large amount of the anti-offset liquid is scraped off.If appropriate treatment is not taken, a large amount of the scraped liquid will accumulate at the tip of the separation member for other sizes mentioned above, and this accumulation will be used next time. When changing the size of the carrier used for fixing, it adheres to the carrier and creates large stains.Even if you do not change the size of the carrier used for fixing, the anti-offset liquid applied to the fixing roller If the amount exceeds the appropriate amount range, or if the application of the anti-offset liquid and the rotation of the fixing roller are not interrupted even when fixing is temporarily interrupted, a large amount of liquid has been scraped off by the separating member. On the other hand, in Japanese Unexamined Patent Publication No. 8704/1983 and Japanese Utility Model Application No. 0248/1983, the anti-offset liquid scraped off by a separation member is A fixing device is disclosed that is devised to prevent the formation of pools on the separating member.

In the former device, an anti-offset liquid-absorbing material, such as a pad made of tightly entangled fibers, is embedded in the separating member from the tip in contact with the fixing roller toward the rear. This pad absorbs the scraped liquid and prevents it from accumulating on the separation member. In the latter device, a hole or recess is provided rearward from a position slightly behind the tip of the separating member, or a pad is embedded as described above, whereby the liquid scraped from the fixing roller is removed from the tip of the separating member. is now being removed. Although these known devices are somewhat effective in limited applications, they all have drawbacks that cannot be ignored. That is, in the device described in the above-mentioned document, the anti-offset liquid that is once accumulated in the pad embedded in the separation member or in the holes or recesses provided in the separation member is then removed when the pad becomes saturated with liquid or when the anti-offset liquid is accumulated in the hole or recess provided in the separation member. When the recess is filled with liquid, the liquid is intermittently dripped from the separating member onto the fixing roller due to the action of gravity.

The liquid applied to the fixing roller in this way forms a thick liquid layer on the roller, but this layer is then leveled to some extent by the anti-offset liquid application member in contact with the fixing roller. It was determined that the layer was not evenly spread over the entire roller and remained as a much thicker layer than in other areas. The higher the speed of the fixing roller relative to the liquid applying member, and the narrower the contact area between the liquid applying member and the fixing roller, the thicker the layer formed by the dripping liquid remains. There is a risk that such a thick liquid layer will adhere to the carrier and cause stains. Furthermore, the above-mentioned document discloses a fixing device in which the fixing roller to which the anti-offset liquid is applied is located below the pressure roller, and the separation member is therefore located below the carrier conveyance path. . However, in a fixing device in which the fixing roller is disposed above the pressure roller, the carrier is passed through the nip with the powder image bearing surface facing upward, and the separating member is positioned above the carrier travel path. , the use of a separation member in which a pad is simply filled or a hole or recess is provided as described in the above-mentioned document sufficiently prevents the carrier from being contaminated by the liquid scraped by the separation member. Can not do it. In other words, in a device configured in this way,
After the pad is saturated with liquid or the holes and recesses are filled with liquid, the liquid that has overflowed or cannot enter these reservoirs is drained under the action of gravity to the bottom of the separation member. For example, the droplets or liquid layer will accumulate on the surface, such as the tip, and grow, but in this case, since the carrier contacts the lower surface of the separation member of the carrier, the droplets or liquid layer will grow. The liquid layer will cause large stains. However, if carriers of multiple sizes are to be selectively fixed, it is necessary to control the amount of anti-offset liquid applied to the fixing roller to an appropriate amount for the separation member that contacts carriers of any size, and to control the amount of anti-offset liquid applied to the fixing roller. If the liquid application to the fixing roller is also interrupted during the temporary interruption, the amount of dirt adhering to the carrier can be reduced for the same reason as mentioned above. However, even if this is done, liquid droplets or liquid layers will grow large as described above if the separation member does not act on the carrier of the size currently being fixed, so when changing the size of the carrier to be fixed. These large droplets or liquid layers adhere to the carrier for the first few leaves, resulting in large stains. The main purpose of the present invention is to solve the problems of the prior art in preventing anti-offset liquid from forming on a separating member. There is a device to prevent irregular dripping of liquid.

In order to achieve the above object, the present invention includes a slit-like groove in a separating member that separates an image carrier from a fixing roller.
The liquid guide member is provided with a slit-like groove that is provided on the separation member and guides the anti-offset liquid adhering to the separation member by capillary development, and a slit-like groove that is connected to the slit-like groove of the separation member and that is connected to the separation member. a liquid guide member that is brought into contact with the surface of the roller on the downstream side in the rotational direction of the roller with respect to the contact portion between the member and the roller, and is attached to the separating member through the slit-like groove and the liquid guide member. There is also a fixing device characterized in that the anti-offset liquid is guided to the roller.

Specific embodiments of the present invention will become clear from the embodiments of the claims, and embodiments of the present invention will be described below.

The explanation will be given below with reference to the drawings.

First, an electrophotographic copying apparatus in which a fixing device according to the present invention can be used will be explained with reference to FIG.

Reference numeral 1 denotes a photosensitive drum, which has an electrophotographic photosensitive member 1'' formed by layering a conductive layer, a photoconductive layer, and a transparent surface insulating layer in this order, and is rotated in the direction of the arrow by an electric motor (not shown).

The surface of the photoconductor 1'' is first charged in a saw-like manner by the corona discharger 2, and the charging polarity is positive if the photoconductive layer is an N-type semiconductor, and negative if it is a P-type semiconductor.Photoconductor 1″
is then subjected to AC or DC corona discharge of opposite polarity to that of the discharger 2 by the corona discharger 3, and at the same time, the optical image of the document 0 is exposed to slit light. The document 0 is placed on a document table 4 and illuminated by a lamp 5, and the document table 4 moves in the direction of the arrow in synchronization with the rotation of the drum 1 in order to scan the document 0. After the scanning is completed, the document table 4 moves back and returns to the previous starting position. Light from the document moving forward with the table 4 is reflected by the mirror 6 and directed toward the in◆mirror lens 7. Lens 7 projects a light image of document 0 onto photoreceptor 1'' through the aperture of corona discharger 3. Photoreceptor 1'' is then uniformly exposed over its entire surface by lamp 8. As a result, a high-contrast electrostatic latent image is formed on the photoreceptor.

This latent image is developed by a developing device 9 such as a magnetic brush type. That is, the developing device 9 supplies colored powder (toner) charged to the opposite polarity to the surface charge of the latent image corresponding to the bright or dark portions of the optical image onto the surface of the photoreceptor 1''. The toner image formed on the surface of the photoreceptor 1'' is transferred to a transfer material such as plain paper or synthetic resin film. 10
1 is a first paper feeding cassette, and 11 is a second paper feeding cassette, each of which stores transfer papers Pl and P2.

Transfer paper P2 is larger in size than transfer paper P1. For example, assume that the transfer paper P1 has a size of B4, P2A3. 12,13
are the transfer paper take-out rollers, and they are the transfer paper take-out rollers, respectively.
The drum 1 rotates in pressure contact with the transfer papers stacked in the drum 1, and is taken out from the single-sheet cassette in synchronization with the rotation of the drum 1 and sent to the timing roller 16 through guide plates 14 and 15.

The transfer paper take-out rollers 12 and 13 are selectively operated according to the operator's selection of the transfer size. The timing taker 16 rotates in synchronization with the rotation of the drum 1, and moves the transfer paper through the guide plate 17 at the same speed as the circumferential speed of the drum 1 so that the leading edge of the paper almost coincides with the leading edge of the toner image of the document 0. Send it out. The transfer paper circle or P2 supplied in this way is conveyed in contact with the photoreceptor 1'', but its back surface is charged with the opposite polarity to the toner by the corona discharger 18.
Under the action of the electrical charges, the toner image on the photoconductor 1'' is attracted to the transfer paper. That is, the toner image is transferred to the transfer paper P1 or P2. During the above transfer process, the toner image on the photoreceptor 1'' is transferred to the transfer paper P1 or P2. Since it is in close contact with the photoreceptor 1'', it is necessary to peel it off from the photoreceptor. For this purpose, the copying machine shown in FIG. 1 uses a separation belt mechanism.

That is, 19 is a thin tube belt that is brought into contact at a fixed position with the peripheral surface of the drum 1 near the right or left end in the direction in which the transfer paper advances. The drum 1 is made to travel at the same speed as the peripheral speed of the drum 1 by the rotation of a pulley 21 which is spanned between the drums and is driven by a motor (not shown). Transfer sheets P1 and P2 of different sizes are both sent to the transfer section so that the right or left end in the direction of travel is placed on the belt 19. That is, cassette 10
, 11 are arranged so that the right end of the transfer paper P1 and the right end of P2, or the left end of P1 and the left end of P2 are fed to the same position of the roller 16 and pass through the same path of the guide plate 17. As mentioned above, one end of the transfer paper is attached to the belt 19.
Since the transfer paper is placed on the drum 1, the transfer paper is also separated from the drum 1 at the place where the belt 19 separates from the drum 1, ie, at the pulley 20. Transfer paper of any size can be transferred using this one belt, without having to displace the contact position of this belt with drum 1 in a direction parallel to the rotation axis of the drum in accordance with the size of the transfer paper. After the process, it can be separated from the drum 1, that is, the photoreceptor 1''.The transfer paper P1 or P2 separated from the photoreceptor 1'' as described above, that is, the transfer paper carrying the toner image, is separated by a pulley 20 and a roller 24. It is placed on the guide plate 25 and sent to the fixing device.

The transfer paper that has slid on the guide plate 25 enters a nip formed by a heated fixing roller 26 and a pressure roller 27 that is in pressure contact with the fixing roller 26. The toner image bearing surface of the transfer paper is in contact with the fixing roller 26 and the pressing roller 27
presses this transfer paper against the fixing roller 26. For example, the roller 27 is configured to reciprocate a short distance in the vertical direction as shown in the figure to come into contact with and separate from the fixing roller 26. For example, when the lower ram 1 starts rotating, it comes into pressure contact with the roller 26, and is first pressed against the fixing roller 26 by the operator. The transfer paper is controlled to be released from the roller 26 after the fixing process for a set number of transfer paper sheets is completed. The roller 26 is rotationally driven by a motor (not shown), and for example, the roller 27 is controlled to be rotationally driven during a period in which it is pressed against the roller 26 side. As the roller 26 rotates, the roller 27 also rotates by friction, and the transfer paper is fed through the nip formed by both rollers while undergoing a fixing process. When the toner melts, in order to prevent it from adhering to the fixing roller 26 and then offsetting to the transfer paper, a liquid such as silicone oil that has a high effect of preventing toner adhesion, that is, an offset prevention liquid, is applied to the surface of the roller 26. Apply to.

This is accomplished by a coating means including an anti-offset liquid coating roller 28. Further, the transfer paper that comes out of the nip is normally in close contact with the fixing roller 26, but in order to peel it off from the roller 26, a separation claw 29 is used to remove the transfer paper from the nip as shown in the figure. Roller 2 on the side
6. With this claw 29, the roller 2
The transfer paper separated from 6 is sent to a guide plate 30 and a discharge roller 31, and this roller 31 discharges the fixed transfer paper, that is, the copy, to a tray 32. As mentioned above, all sizes of transfer paper are transported so that the right or left edges are aligned, so the right or left edge of each size of transfer paper should be in the same place at the fixing device mentioned above. pass.

Therefore, there is a region on the left or right end side of the fixing roller 26 that contacts, for example, A3 size paper but does not contact B4 size paper. Furthermore, after the transfer is completed, the photoreceptor 1''
The remaining toner is wiped off by an elastic blade 33 such as a comb that is in contact with the toner, and the toner is again input into the above-described image forming cycle.

Next, the fixing device shown in FIG. 1 to which the present invention can be applied will be explained in detail.

As explained in FIG. 1, 26, 27, and 28 are fixing, pressing, and coating rollers, respectively.

Although not shown in FIG. 1, the coating roller 28 is coated with a layer 35 of an oil-absorbing material such as a densely entangled sheet of fibers such as felt, which is applied to the coating roller 28 to prevent offset (separation). (also called molding agent) is supplied. For example, silicone oil is used as this liquid. One end of the felt layer 35 is immersed in silicone oil in an oil bath 36. Therefore, the felt layer 35 sucks up the silicone oil by capillary action and supplies it to the surface of the roller 28. On the other hand, the roller 28 is rotatably supported by a frame (not shown) and is brought into contact with the fixing roller 26. Therefore, the roller 28 frictionally rotates as the fixing roller 26 rotates, and the silicone oil applied to the roller 28 from the felt layer 34 is then applied to the roller 28.
6. Due to the action of the coating roller 28, a uniform and thin oil film is formed on the fixing roller 26.
Note that a shaft 341 rotatably supported by a frame (not shown) is attached to the felt layer support plate 34. Therefore, the plate 34 is rotated so that the felt layer 35 approaches and separates from the application roller 28. In order to perform this operation, the shaft 341
An arm 342 is fixed to the holder, and an extraction shaft of an electrode plunger 343 is pivotally attached to the arm 342. While the fixing roller 26 is rotating or while the roller 27 is being pressed toward the push button 26 side, the plunger 333 is actuated to apply the felt layer 35 to the coating roller 28.
contact with. Alternatively, detect the amount of oil on the roller 26 or 28 and if it is excessive, remove the felt 35 from the roller 28.
It is also preferable to control the operation of the plunger 343 so as to bring the feltner 35 into contact with the roller 28 when the amount is less than the required amount. The fixing roller 26 is a hollow metal vibrator 26 that is rigid and has good heat conductivity.
1 is coated with a thin silicone rubber layer 262.

The reason why the silicone rubber layer 262 is provided is that melted toner is difficult to adhere to it, and together with the silicone oil, the offset prevention effect is further enhanced. An infrared lamp 263 is disposed in the hollow vibrator 261, and heats the surface of the roller 26 from inside to raise and maintain a temperature at which the toner can be melted. This lamp 263 is set to 0N of the main switch of the copying machine. ．． It is designed to blink at 0FF, and as long as the main switch is 0N, it continues to light even if the rotation of the roller 26 has stopped, and the surface temperature of the fixing roller is maintained within a certain temperature range by a control circuit (not shown). Ru. On the other hand, the pressure roller 27 is a rigid core rod 2 made of metal or the like.
71 is coated with a relatively thick elastic material layer 272 such as silicone rubber.

Therefore, when pressed against the fixing roller 26 side, the pressure contact surface is recessed, forming a relatively long nip in the transfer paper traveling direction. This allows a relatively long period of time for the transfer paper to be pressed against and heated by the roller 26, allowing good melting of the toner and therefore good fixing to the transfer paper. Reference numerals 291 to 294 are the aforementioned separation claws, and in order to separate the transfer paper that comes out of the nip in close contact with the roller 26 from the roller 26, a plurality of claws are provided along the longitudinal direction of the roller 26 as shown in the figure. is provided.

Each pawl 241 to 294 is rotatably supported by a shaft 295 parallel to the rotation axis of the roller 26. And in Figure 3 [
As shown, the tip of each claw 291 to 294 is connected to a spring 297.
The roller 26 is biased so as to come into light pressure contact with the surface of the roller 26. One end of the spring 298 is locked to a beam 296 (not shown in FIG. 2) provided parallel to the shaft 295, and the other end is locked to the back surfaces of the claws 291-294. Note that, for example, B4 size transfer paper does not come into contact with the claw 291, and only A3 size transfer paper comes into contact with this claw 291, and the other claws 292, 293, and 294 are used for both B4 and A3 size transfer paper. Anything that the paper comes into contact with. That is, as explained in FIG. 1, each size of transfer paper is separated from the drum 1 by the one belt 19, so both the B4 size transfer paper P1 and the A3 size transfer paper P2 have the side with the claw 294. The objects are transported so that the movement trajectories of the ends almost coincide with each other. Furthermore, the reason why one sheet of transfer paper is separated from the roller 26 with multiple claws is to reduce the burden on one claw, and to ensure separation, etc. The transfer paper separated from the rollers by the claws 291 to 29 or claws 292 to 294 hangs downward, and is then guided by the guide plate 30 (shown in Figure 1) to the discharge roller 31 (shown in Figure 1). (shown). Now, the present invention is effective when applied to the separation members 291 to 294 in the fixing device shown in FIG. There is a particularly remarkable effect when applied to a separation member that is not a separation member through which toner image bearing members of various sizes pass in common.

Therefore, in order to make the features of the present invention even clearer, we will introduce the second
When the separation member 291 shown in the figure uses a separation claw as described in the above-mentioned known literature, FIGS. 4A and BL and 5A and 5B will be explained. Each figure a is a side view, and each figure b is a bottom view of each separating claw. In each figure a, a toner image carrier (transfer paper, etc.) carrying a toner image T, P, is sent in the direction of the arrow and undergoes a fixing process. As shown in FIGS. 4A and 4B, the separating claw 29A has a recess 29A1 on the flat guide surface side of the toner image carrier.
A certain amount of silicone oil scraped off from the roller 26 by the tip of the nail 29A that is in contact with the fixing roller 26 can accumulate in the depression 29A1. As shown in FIGS. 5A and 5B, the separation claw 29B has a groove 29B1 formed on the toner image carrier guide surface side up to the tip end.
Oil absorbent inside. For example, a felt 29B2 made of densely entangled fibers is embedded.

The oil scraped off from the roller 26 by the tip of the claw 29B can be absorbed and retained in the felt 29B2 up to a certain amount. Now, a large number of small-sized, for example, B4 toner image carriers were continuously fixed using the apparatus shown in FIGS. Therefore, the B4 toner image carrier is not in contact with the claws shown in FIGS. 4 to 8), and then the fixing process for a large size, for example, A3 toner image carrier, is started (A34 paper is shown in FIG. 2). 6), large and conspicuous oil stains S1 are formed at the tips of the first few leaves of the A3 toner image carrier, as shown in FIG. This is caused by the silicone oil that has accumulated at the tips of the separating claws 29A and 29B during the B low fixing process and adheres when the leading edge of the A3 paper comes into contact with the separating claws.

That is, as described above, the recess 29A1 of the claw 29A, the claw 29
The felt 29B2 of B retains silicone oil to some extent, but the oil scraped off from the fixing roller 26 beyond its retention capacity accumulates in the form of particles and layers at the tip of the separating claw.

The larger the amount of oil scraped, the larger the oil particles and layer grow, causing large stains.
In addition, oil accumulated in the recess 29A1 or oil exuded from the oil-saturated felt 29B2 drips or is pulled by the toner image carrier/carrier due to contact with the toner image carrier/carrier, and the toner is Large streak-like oil stains S2 are often formed even in the deep interior of the image carrier. The present invention attempts to solve these inconveniences by eliminating stains at all or keeping them to a small size so as not to impair the beauty of the copy. Fig. 7A,
b is an explanatory diagram of one embodiment of the present invention. A narrow groove 29C1 is provided on the transfer paper guide surface side of the separating claw 29C from the rear end to the front end, that is, to the part that abuts the fixing roller 26, through which silicone oil can be transported by capillary action. An oil-absorbing member, such as a felt 29, is provided on the rear end surface of the claw 29C so as to connect with the groove 29C1.
C2 is attached, and on the other hand, the rear end 29C2 of this felt 29C2 is brought into contact with the fixing roller 26. The contact position is downstream of the position where the tip of the claw 29C contacts the roller 26 and upstream of the silicone oil application roller 28 with respect to the rotational direction of the roller 26. (The same applies to the following embodiments) The silicone oil scraped off from the fixing roller 26 by the tip of the nail 29C passes through the groove 29C1 through the felt 29C by capillary action.
2. The felt 29C2 absorbs this silicone oil and conveys the oil to its rear end side by capillary action. Since the rear end of the felt 29C2 is brought into contact with the roller 26 as described above, the oil conveyed into the felt is again brought into contact with the roller 26.
6. Evenly coated. In this way, felt 29C2
absorbs silicone oil, while this felt 29
Since the oil flows out from C2 one after another, this felt 29C2 can continue to absorb the oil scraped off by the claw 29C from the roller 26, which is conveyed by the groove 29C1 one after another. Therefore, it is possible to prevent oil particles or layers from forming and growing on the tip of the transfer paper guide surface of the claw 29C. Therefore, oil stains S1 and S2 as shown in FIG. 6 are not formed, or even if they are formed, they are smaller. Figure 8A
, b, and c are illustrations of other embodiments of the present invention.

3c is a cross-sectional view of the separating claw taken along a plane perpendicular to the longitudinal direction of the groove. The claw 29D is in contact with the fixing roller 26 at its linear tip. The pawl 29D has a groove 29D1 on the flat transfer paper guiding surface side for conveying oil by capillary action.
This groove 29D1 is formed from a position slightly backward from the tip of the claw 29D, that is, a contact portion with the fixing roller, that is, a position slightly closer to the rear end side than the tip, to the rear end. As a result, paper dust attached to the transfer paper enters the groove 29D1 and accumulates there, and the accumulated paper dust prevents the flow of oil in the groove 29D1, or It is possible to prevent an accident in which a lump of paper powder soaked in oil adheres to the transfer paper and becomes a stain. Tip of claw 29D and groove 29D
The distance from the tip of No. 1 may be about 0.5 to 5 Tr0rL.
If it is smaller than 0.5 cm, the leading edge of the transfer paper will easily hit the groove 29D1.

In other words, paper dust can easily enter the groove. If it is larger than 5, it becomes difficult for the oil scraped off from the roller 26 to reach the groove 29D1. In other words, there is a strong tendency for oil particles to grow at the tip of the nail. Moreover, by not providing a groove all the way to the tip of the claw, a certain narrow groove can be easily formed on the claw. The groove 29 is scraped off from the fixing roller 26.
The silicone oil transported by D1 by capillary action is
It is attached to the rear end surface of the claw 29D and absorbed by the felt 29D2 connected to the groove 29D1. The rear end side of the felt 29D2 is brought into surface contact with the fixing roller 26 as in FIG. 7. Therefore, as described in FIG. 7, oil successively escapes from the felt 29D2 to the roller 26. Therefore, the felt 29D2 can always absorb the oil in the grooves 29D1, thereby preventing oil particles or layers from forming and growing at the tips of the claws 29D. In addition, in FIG. 8, the depth of the groove 29D2 gradually increases in the direction from the tip to the rear end of the claw 29D (depth of about 3 to 7 wrfn at the deepest part). This is to facilitate forming narrow grooves on the pawl, and to increase the holding power and amount of oil that can be held at the rear end of the pawl.

Also in the device of FIG. 7, the depth of the groove 29C1 may be gradually increased in the above direction. Furthermore, in the devices shown in FIGS. 7 and 8, the grooves 29C1 and 29D1 for conveying silicone oil have a width of 0.1.
~2? It is desirable that the

If it is narrower than 0.1T1Un, the amount of oil conveyed per unit time will not be much different from the amount of oil scraped off from the roller 26 per unit time.

27017 again! If it is wider, the oil transport force due to capillary action will be smaller. FIGS. 9A, b, c, and d are explanatory diagrams of still other embodiments of the present invention.

Also in this example, the separating claw 29E is provided with a thin tube groove 29E1 (preferably having a width of about 0.1 to 2 Tmm inside for the same reason as above) on the transfer paper guide surface side.
Similarly to the example in FIG. 8, E1 is bored from a position set back a short distance (preferably about 0.5 to 5TT0n for the same reason as above) from the tip of the claw to the rear end of the claw 29E, and the groove 29E1 The depth gradually increases in the direction from the tip of the claw 29E to the rear end (depth of about 3 to 7 T$t at the deepest part)
are doing. In this example, the oil conveying groove 29 is caused by capillary action.
The width of the opening 29E'' to the transfer paper guide surface of E1 is slightly wider than the width of the narrow interior 29E''. This is because the oil scraped off from the fixing roller 26 is responsible for the capillary action. This is to make it easier for the oil to enter the narrow part 29E inside the groove, thereby improving the oil conveyance speed. As such, the opening 29Er of the groove 29E1 is
A slope Al, 7X2, which connects the transfer paper guide surface and the internal narrow width part 29E, respectively, and is inclined so that the distance between the two gradually increases in the direction from the inside of the groove to the outside.
, A2.

The opening angle α of the slopes Al and A2 was about 70 to 1400, and particularly good results were obtained with 900 to 1200. The mouth width W of the opening 29E1'' is preferably about 1 to 4T0fL. Also, the depth d of the opening 29E1'' is 0.3
It is desirable that it is about 2.5 TWL. α,W. d
If it becomes larger or smaller than the above-mentioned range, the ease with which oil can infiltrate into the internal narrow width part 29E' of the groove decreases. Although it is formed over the entire length of the width portion 29E, the claw 2
9E scrapes off the oil and oil from the roller 26 to the narrow part 2.
9E"There is something to make it penetrate quickly, so narrow part 2
It is also possible to form it only on the leading end side of 9E and not to provide it on the rear end side that connects to the felt.

As described above, the groove 29E1 is filled with felt 29E.
2 are connected.

This felt 29E2 is attached to the rear end surface of the claw 29E as in FIGS. 7 and 8, and one end side is brought into surface contact with the fixing roller 26. The oil scraped off from the roller 26 by the tip of the claw 29E passes through the relatively wide opening 29E1'' of the groove 29E1 to the narrow portion 29E''.
and this oil is transferred to the felt 29E2 by capillary action. The felt 29E2 absorbs the conveyed oil, and on the other hand, the absorbed oil is conveyed to the rear end by capillary action and reapplied to the roller 26 at the position of contact with the roller 26. Therefore, the ability to remove oil from the tip of the claw 29E2 is not lost, and the ability to remove oil from the tip of the claw 29E2 is always maintained, thereby eliminating the situation where oil particles or layers grow and grow on the transfer paper guiding surface of the claw 29E2. be able to. In addition, since the oil scraped off by the claws is reapplied onto the roller 26, there is no problem that only the roller surface located on the claw portions would lack oil. In fact, a test was conducted in which up to 100,000 sheets of B4 paper were continuously fixed using a fixing device in which the claw 29E in FIG. 9 was applied to 291 in FIG.

(Meanwhile, the B-paper is not in contact with the claw J29l in Fig. 9.) After 100,000 sheets of B4 paper were continuously fixed as described above,
A? When the fixing process was started, there were no oil stains on A-so at all. Also, no paper powder was clogged in the groove 29E1. Note that the opening 29E1'' may be formed of a stepped surface, etc., instead of the slope Al, as described above, but it is preferable that the opening 29E1'' be formed of a slope because the oil flow is smoother. In the embodiment described above, in order to convey oil from the tip to the rear end of the separation claw, grooves were provided in the claw to cause a capillary phenomenon, but as shown in FIGS. The felt 29F1 may be buried in the transfer paper guide surface side.

The rear side of this felt 29F1 is extended and fixed to the rear end surface of the claw 29F, and the rear end portion is brought into contact with the roller 26. That is, the felt that conveys oil from the tip to the rear end of the pawl 29F and the felt that conveys oil from the rear end of the pawl 29F to the roller 26 are integrally formed in this example. be. Of course, the felt member embedded in the claw and the felt member that abuts the roller 26 may be separate bodies, and both may be joined at the rear end of the claw or the like. In addition, in this example, the felt 29F1 is 0.5 mm from the tip of the nail.
~It is filled in from the position 5th back, but this is to prevent paper dust from getting stuck in the felt eyes, and the 5th
As shown in the figure, the tip of the claw 29F may be aligned with the tip of the embedded felt.

Although the purpose can be achieved by using a device in which felt is embedded in the nail as described above, the amount of oil conveyed per unit time is relatively larger in the groove than in the felt. (Accordingly, in the examples shown in Figures 7, 8, and 9, the area of the cross section of the groove cut into the pawl is larger than the area of the cross section of the same upper surface of the felt member perpendicular to the oil feeding direction. Therefore, the oil conveying speed of the felt member is equal to or faster than that of the groove.) Therefore, the oil scraped off from the roller 26 can be quickly removed from the tip side of the claw.
and the seventh, eighth, and eighth in that the separation claw can be made smaller.
The device shown in Figure 9 is superior. On the other hand, with the device shown in Figure 10, as long as the oil is smoothly conveyed through the felt, the oil holding power of the felt is strong, so even if an extremely strong impact is applied, the oil will not drip and stain the transfer paper. It also has advantages. In each of the embodiments of the present invention described above, it is desirable that the length of contact between the tip of the separating claw and the fixing roller (with respect to the longitudinal direction of the fixing roller) is approximately 2 to m.

If the length is shorter than 2Tr0n, the strength of the tip of the claw is weak and the circumferential surface of the fixing roller is likely to be damaged.

If the length is longer than 10, too much oil will be scraped off, and the separation performance of the toner image carrier from the roller will deteriorate. The separation claw is made of heat-resistant synthetic resin such as aromatic polyester, polyimide, polyamideimide, etc. in consideration of strength and workability, and the guide surface that comes into contact with the toner image carrier is coated with tetrafluoroethylene resin. This may be applied to prevent toner from sticking. The placement position and posture of the claws will be explained using Figure 11. Separation claw 2
The tip of the separation claw 29 is brought into contact with the roller 26 at an angular position β from the line connecting the rotation centers of the rollers 26 and 27, and the toner image carrier guiding surface of the separation claw 29 is in contact with the roller 26 at the tip of the separation claw 29. It is assumed that the angle γ is formed with a line circumscribing the roller 26 in the section. It is preferable that β is 40 to 70 degrees, and γ is 120 to 180 degrees. Of course, both should be determined in consideration of the transfer paper conveyance path.
The larger both β and γ are, the better. When β is large, it is easy to separate the toner image carrier from the roller 26, and when γ is large, neither the claw nor the toner image carrier is subjected to excessive force during this separation. The amount of silicone oil applied to the fixing roller 26 is suitably 5 x 10-4 to 1 x 10-2 CC/1C0py. Here, in order to make the effects of the present invention clear,
4 and 5 and 7, 8, 9, and 10 according to the present invention
The results of experiments conducted using the device shown in the figure are graphed in FIG.

The horizontal axis shows the number of sheets of B4 size paper that is continuously fixed, and then A3 size paper.
Indicates that the fixing process for paper of the same size has started. (During the B4 size paper fixing process, the separating claws in each of the above figures are in a non-contact state with the transfer paper.) The vertical axis indicates the size (area) of the oil stain formed on the first A3 size paper. The number N given to a curve indicates that the curve is the characteristic curve of the device of FIG. Fourth
The printing device has been continuously processing about 50 stains on B4 paper, and it leaves noticeable and large stains on A3 paper. The apparatus shown in FIG. 5 is almost the same as the apparatus shown in FIG. 4 when approximately 2,000 sheets of B-shot are processed continuously. The devices shown in Figures 7, 8, and 10 produce small stains. However, the stains are much smaller than the stains produced by the apparatus shown in Figures 4 and 5, and are not large enough to spoil the beauty of the copy paper. Figure 8 Apparatus, No. 7
The size of the stains formed in the device shown in Fig. 1 and the device shown in Fig. 10 gradually increases in size, but this is due to the speed at which oil is removed from the tip of the claw, and the fact that when separating the copy paper, the copy paper is removed from the tip of the separation claw. This depends on the magnitude of the phenomenon in which the oil present in the groove is pulled by the copy paper and adheres to the copy paper at the moment of contact with the copy paper. As for the size of the stain caused by the latter, a smaller amount of oil retained at the tip of the nail will give a better result. In other words, it is better not to provide a groove for holding oil near the tip. Almost no sewing machine can be made with the device shown in Figure 9. In the embodiment described above, the separating means shown in FIGS. 7, 8, 9, and 10 is applied only to the claw 291 in FIG. ，
Nos. 293 and 294 have explained the case in which a means for scraping oil from the tips of the claws is not added (using claws that do not have grooves or embedded felt as described above), but of course all separating claws are provided with a seventh, The embodiments shown in FIGS. 8, 9, and 10 can also be applied.

Further, in the embodiments described above, when the fixing roller is located above the pressing roller, that is, the separation claw is brought into contact with the upper roller with the toner image carrier guide surface facing downward, and the toner image carrier is attached to the upper roller. This is an example of a fixing device in which the fixing roller passes under the pressure roller. The present invention can also be applied to a fixing device in which the toner image bearing member is brought into contact with the separation claw and passes over the separating claw.

One such embodiment is shown in FIGS. 13A, b, and c. The meanings of the symbols are the same as in each of the figures described above. 13th
In the illustrated embodiment, a hollow cylinder 261 made of a rigid body such as metal
The fixing roller 26 has a thin layer 262 of an elastic material such as silicone rubber on the circumferential surface of the fixing roller 26, and the pressure roller 26 has a thick layer 272 of an elastic material such as silicone rubber around a roller 271 of a rigid material such as metal. It is located.

As described above, the pressing roller 27 has a pressing habit on the fixing roller 26 side at least during the fixing process, so that a nip is formed between the two rollers 5. The fixing roller 26 is rotated by a motor (not shown) in the direction of the arrow at least during the fixing process as described above, and the pressure roller 27 is frictionally rotated θ as the fixing roller 26 rotates. An infrared lamp 263 is disposed in the hollow part of the fixing roller 26, and is designed to heat the circumferential surface of the elastic layer 262 to a temperature at which the toner can be melted. An anti-offset liquid (also referred to as a release agent) such as silicone oil is applied to the circumferential surface of the fixing roller 26 in order to prevent toner offset.

That is, numeral 28 is a coating roller that is brought into contact with the circumferential surface of the fixing roller 26 and rotated by friction.
The application roller 28 is adapted to abut the other end of a liquid-absorbing member 34 such as felt, one end of which is dipped in silicone oil stored in a tank 36. The back side of the felt 34 is supported by a plate 35, which is fixed to a rotatable shaft 35, which in turn is fixed to an arm 342. On the other hand, since the arm 342 is connected to the extraction shaft of the electromagnetic plunger 343, the felt 34 is connected to the roller 28 by the operation of the plunger 343. As mentioned above, the amount of siliron oil around the fixing roller 26 is detected, and if the amount becomes too low, the plunger 343 is actuated to move the felt 34 to the roller 28.
What is necessary is to make it come into contact with.

Silicone oil is supplied from the tank 36 to the fixing roller 26 through the felt 34 and the roller 28. A carrier (such as paper) P carrying the toner image T is sent in the direction of the arrow with the toner image carrying surface facing downward, and is fixed by a pressing roller 26,
The nip formed by 27. pass.

That is, the toner image bearing member P is brought into pressure contact with the fixing roller 26 by the pressing roller 27, and at this time, the toner image bearing surface comes into contact with the fixing roller 26, and the toner is heated and melted to be attached to the toner image bearing member P. Sticky. roller 2
6,27! As described above, the toner image carrier P that has exited the nip tends to be fed while remaining in close contact with the fixing roller 26, but in order to peel it off from the roller 28, it is moved in the longitudinal direction of the fixing roller 26 as explained in FIG. Separation claws are provided at multiple locations along. The carrier P separated from the fixing roller by these three claws moves to the next storage station while sliding on the guide surfaces of each claw. Each separating claw is rotatably supported by a shaft 295 as shown in FIG. In the case of the illustrated embodiment, the spring 297, beam 296, etc. shown in FIG. 3 may be omitted. That is, the tip of each claw can be brought into contact with the circumferential surface of the fixing roller 26 by the action of gravity.
Now, as already explained, when fixing a plurality of sizes of toner image carriers, among the plurality of claws, for example, the claw disposed on the far right or the left in the direction of movement of the carrier P, etc. The large-sized carrier P functions to separate from the roller 26, but does not come into contact with the small-sized carrier P.

Such claws scrape off a relatively large amount of silicone oil from the fixing roller 26 during the fixing process on the small-sized carrier P.
If the scraped oil accumulates in particles or layers on the toner image carrier guide surface of the nail and grows, it will adhere to the large toner image carrier and become a large stain, and it will also accumulate on the nail. If oil drips onto the fixing roller 26, it will cause oil unevenness on the fixing roller 26, which will be transferred to the toner image carrier and cause stains. In order to avoid such inconvenience, the embodiment shown in FIG. 13 is provided with separation means as shown in FIG. 9. The separating claw 29E is simply brought into contact with the fixing roller 26 at its tip end with the toner image carrier guiding surface facing upward, and its structure is the same as that described in the explanation of FIG. 9 and the like.

That is, for the same reason as described in FIG. 9, the claw 29E (
7) On the guide surface side, an oil conveying groove 29E1 is provided from a contact portion with the roller 26, that is, a position set back by about 0.5 to 5 Tf0Tt toward the rear end from the tip end. The groove 29E1 has an internal narrow part 29E (width is about 0.1 to 2T011 for the same reason as described in FIG. ) and an opening 29E1'' which is slightly wider than the narrow portion 29E detailed in FIG. 9d. The opening 29E1'' consists of two slopes as shown in FIG. 9d, and for the same reason as described in FIG. 9, the opening angle α is about 70 to 140, and the opening width W is about 1 to 4Tr$t. , and the depth d is about 0.3 to 2.57707!.The opening 29EF may also be formed of a stepped surface instead of a slope.The rear end side of the claw 29E is made of oil absorbent material such as felt. A liquid guiding member 29E2 is attached.

As in the previous embodiment, one end of the felt 29E2 is connected to the groove 29E1, and the other end is brought into contact with the fixing roller 26. The contact portion with the fixing roller 26 is located downstream of the contact portion between the claw 29E and the roller 26 and upstream of the application roller 28 in the rotational direction of the roller 26. The felt 29E2 has a cross-sectional area larger than the groove 29E1 in a plane perpendicular to the oil conveyance direction so that the oil conveyance speed thereof is equal to or higher than that of the groove 29E1.

Now, the silicone oil scraped off from the fixing roller 26 by the tip of the claw 29E enters the groove 29E1.

At this time, the opening 29E" contributes to improving the infiltration speed. The groove 29E1 conveys the infiltrated oil to the rear end side of the nail mainly due to the action of capillarity. This conveyed oil is then passed through the felt. On the other hand, the felt 29E2 evenly applies the absorbed silicone oil to the fixing roller 26 at the contact portion with the fixing roller 26. Therefore, the felt 29E2 loses its ability to absorb oil. Because of this, oil particles or layers are not formed or grown on the tip of the toner image carrier guide surface of the claw 29E, and therefore large stains are not formed on the tip of the toner image carrier. It disappears.

Furthermore, as mentioned above, the anti-offset liquid scraped off from the fixing roller by the separating claw is continuously transferred in minute amounts onto this roller by a liquid guiding member (liquid absorbing member such as a felt member) that is in contact with the fixing roller. This makes it possible to uniformly apply the liquid back to the fixing roller, thereby eliminating the drawbacks of the previously mentioned known devices, namely, the formation of a thick layer of liquid unevenly when the liquid is dripped onto the fixing roller and returned. This also has the effect of eliminating defects such as the possibility that it may adhere to the toner image bearing member and cause stains. Note that the separating means shown in FIGS. 7, 8, and 10 may be used instead of the separating means shown in FIG. 13. Furthermore, it goes without saying that the present invention may also be applied to an embodiment in which the fixing roller is located below the pressing roller, as well as to a separation means in which toner image bearing members of various sizes come into common contact.

Furthermore, the present invention can be applied to a fixing device of a pressure fixing type in which a fixing roller and a pressure roller are brought into contact with each other with strong pressure, and also to a fixing device of an electrofax copying machine in which a photosensitive sheet is used as a toner image carrier undergoing fixing processing. It can also be applied to

Furthermore, the present invention provides toner image bearing members of a plurality of sizes,
It can also be applied to a device that conveys the objects so that the center portions thereof follow the same trajectory, instead of conveying them along the left end or right end. As is clear from the description of the embodiments above, the effect of the present invention is that the anti-offset liquid that adheres to the separation member is not dropped as a dripping liquid as in the conventional method, but is ensured by using the slit-shaped groove. Since the liquid can be guided and supplied in contact with the surface of the fixing roller by the liquid guide member, an uneven liquid level is not formed on the surface of the fixing roller, and liquid stains on the image carrier can be prevented.

[Brief explanation of the drawing]

FIG. 1 shows an electrophotographic copying apparatus using a fixing device according to the present invention, FIG. 2 shows a fixing device to which the present invention is applied, FIG. 3 shows means for pressing the tip of the separating claw against a fixing roller, and FIG. Figures A, b and 5A and b are respectively a device in which a known separation means is applied to the fixing device of Figure 2;
Stains on the toner carrier caused by the fixing device in Figures A and b, No. 7
Figure A9b) Figure 8 A9b9c to Figure 9 A9b9c9dl
Figures 10A and b are examples of the present invention, Figure 11 is the arrangement of separation claws in each example of the present invention, Figure 12 is the effect of the example of the present invention, and Figure 13 is a further example of the present invention. There are diagrams for explaining each of the other embodiments. 26 is a fixing roller, 27 is a pressure roller, 28 is a silicone oil application roller, 29,291 to 294, 29
A, 29B, 29C, 29D, 29E, 29F are separation claws, 29C1, 29D1, 29E1 are oil conveying grooves, 29
E1 is the narrow part, 29E1'' is the opening, 29C2, 29D
2, 29E2, and 29F1 are felt members, and 295 is a support shaft for the separation claw.

Claims (1)

[Scope of Claims] 1. A fixing roller with which the powder image bearing surface of a powder image carrier is brought into pressure contact, means for applying an offset prevention liquid to this roller, and an image carrier that is sent out as the roller rotates. a separating member disposed in contact with the roller to separate it from the roller;
A slit-like groove provided in the separating member and guiding the anti-offset liquid adhering to the separating member by capillary action; and a slit-like groove connected to the slit-like groove of the separating member and a contact portion between the separating member and the roller. a liquid guide member that is brought into contact with the roller surface on the downstream side in the rotational direction of the roller, and the offset prevention liquid adhering to the separation member is guided to the roller by the slit-like groove and the liquid guide member. Features a fixing device. 2. The fixing device according to claim 1, wherein the slit-like groove opens slightly away from the tip of the separating member. 3. The fixing device according to claim 1 or 2, wherein the slit-like groove has an opening width wider than an inner width. 4. The fixing device according to claim 1, wherein the slit-like groove is open to the tip of the separation member. 5. The fixing device according to any one of claims 1 to 4, wherein the liquid guiding member is an anti-offset liquid absorbing material. 6. Claims 1 to 5, wherein the separation member to which the liquid guiding member is coupled is a separation member that does not come into contact with a small-sized powder image carrier among powder image carriers of different sizes. The fixing device according to any one of the above.