JPH05134577A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the forgetting of work at the time of reducing the number of parts, and maintaining and checking by attaching a blade to a stay having a paper powder storage part, and integrally constituting the blade and the paper powder storage part. CONSTITUTION:The width of the blade 101 is set wider than that of an image forming region, and the paper powder storage part 102a having the width slightly wider than the abutting width of the blade 101, is formed on the stay 102, as a stuck material receiving part. In other words, the blade 101 and the stay 102 having the paper powder storage part 102a are integrally composed. Therefore, when the blade 101 and the paper powder storage part 102a are cleaned, at the time of maintaining and checking, the forgetting of either of them, can be prevented. Further, when copying is executed up to the limit of the expected life of the blade 101, the relation of the capacity of the paper powder storage part 102a and the durable life of the blade 101 is set so as to make the part 102a full, so that a paper powder removing unit 100 can be exchanged, whenever the fixed number of copies is obtained, and maintenance work is easily executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a fixing device for fixing an image transferred on a transfer material by a fixing roller pair.

[0002]

2. Description of the Related Art In a conventional fixing device of an image forming apparatus using an electrophotographic system such as a copying machine, heat or pressure is applied to a transfer sheet by passing a transfer sheet as a transfer material between a pair of fixing rollers. In addition, a fixing method of fixing an image on a transfer sheet is widely used.

The fixing device has means for applying oil to the fixing roller and an adhering substance scraping device, and removes adhering substances from the surface of the fixing roller. Applying oil as a releasing agent to the surface of the fixing roller to remove the deposits is to prevent the so-called offset of toner transfer to the fixing roller, to facilitate separation of the fixing roller and transfer sheet, and to perform double-sided copying. Alternatively, it is to prevent the transfer sheet from becoming dirty during multiple copy. The details of the adhering matter scraping device will be described below with reference to FIG.

In FIG. 8, 11 is an upper fixing roller having a heater therein. The surface of the fixing upper roller 11 is kept at a constant temperature, and the image on the transfer sheet is fixed by coming into contact with the image surface (surface) of the transfer sheet. Below the upper fixing roller 11 is a lower fixing roller 1.
2 is arranged in pressure contact with the upper fixing roller 11, and presses against the back surface of the transfer sheet. A coating felt 15 is arranged on the lower fixing roller 12 so as to come into contact with the surface of the lower fixing roller 12, and the oil in the oil pan 14 is sucked up by a capillary phenomenon so that the oil is applied to the surface of the lower fixing roller 12. To supply. Further, it is downstream of the nip portion between the upper fixing roller 11 and the lower fixing roller 12 in the rotational direction of the lower fixing roller 12, and is upstream of the contact position of the coating felt 15 with the lower fixing roller 12 in the rotational direction. A blade 23 formed of an elastic member is disposed in the. The blade 23 is attached to a stay 24 made of sheet metal to form an adhering substance scraping portion, and removes adhering substances on the surface of the lower fixing roller 12.
Further, below the stay 24, there is provided a paper dust receiving tray 26, which is a deposit receiving portion having a storage portion wider than the contact area of the blade 23. It is designed to receive the scraped off paper dust and other deposits.

In the above-mentioned conventional example, the blade 23 is located downstream of the nip portion of the pair of fixing rollers in the rotational direction of the lower fixing roller 12 and upstream of the contact position of the coating felt 15 in the rotational direction. Since the adhered matter such as paper powder is scraped off from the paper, the paper powder does not adhere to the felt 15 and the oil supply amount does not decrease, and the oil is accumulated between the coating felt 15 and the lower fixing roller 12. The mixture of paper powder and oil will not overflow at one time and stain the transfer sheet.

Furthermore, since the paper dust scraped off by the blade 23 is received by the paper dust receiving tray 26, the removed paper dust falls into the oil pan 14 to contaminate the oil or cause the paper dust to spread around. There is no scattering. Further, since it is sufficient to clean only the paper dust receiving tray 26 without cleaning the entire fixing device at the time of maintenance and inspection, the work efficiency can be improved.

[0007]

However, according to the above-mentioned conventional example, since the paper dust receiving tray 26, which is the adhered matter receiving portion, is provided separately from the blade 23 and the stay 24, which are the adhered matter scraping portion, There are problems that the number of points increases and the space efficiency deteriorates. Further, even during maintenance and inspection, there is a problem that only the blade 23 is cleaned or replaced and the cleaning or replacement of the paper dust receiving tray 26 is forgotten.

The present invention solves the above-mentioned problems, reduces the number of parts in an adhering matter scraping device to reduce cost and improve space efficiency, and eliminates erroneous work during maintenance and inspection. Is intended to provide.

[0009]

According to the present invention, the above object has a pair of fixing rollers arranged in pressure contact with each other and rotatably arranged, and the transfer material is nipped and conveyed by the pair of fixing rollers. A fixing device for fixing the unfixed developer image on the transfer material by means of the fixing roller pair, wherein the unfixed developer image bearing surface on the transfer material is held when the transfer material is nipped. In an image forming apparatus provided with a fixing device having an adhering matter scraping device which is arranged so as to face a roller which is in contact with a surface on the back side and is in contact with the surface of the roller, the adhering material scraping device comprises: This is achieved by having an adhering matter scraping section and an adhering matter receiving section, and the adhering matter scraping section and the adhering matter receiving section being integrally formed.

[0010]

According to the present invention, since the deposit scraping portion and the deposit receiving portion of the deposit scraping device are integrally formed, the deposit scraping portion or the deposit receiving portion is replaced during maintenance and inspection. Alternatively, when cleaning, it is necessary to perform maintenance on both of them because the work is performed for each of the integrally formed adherent scraping devices. As a result, the adhering matter can be always removed well by the adhering matter scraping device, and the release agent application on the roller surface can be ensured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a schematic configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 is a copying machine capable of double-sided copying and multiple copying. A paper feed unit 2 is arranged in front of the copying machine 1, and a transfer sheet 8 as a transfer material is accommodated in the paper feed unit 2.

An image forming unit 3 is disposed behind the paper feeding unit 2 and forms an unfixed developer image on the sheet fed from the paper feeding unit 2. A fixing device 4 is disposed behind the image forming section 3, and the sheet conveyed from the image forming section 3 is nipped and conveyed to fix the unfixed developer image. A flapper 5 is provided in the paper discharge section at the rear of the fixing device 4 and conveys a transfer sheet to a double-sided tray 6 at the bottom of the apparatus at the time of double-sided or multiple copying. The transfer sheets are stacked on the double-sided tray 6, and are separated and conveyed one by one by a sheet re-feeding unit 7 arranged in front of the double-sided tray 6 and again copied on the back side in the image forming unit 3 or Multiple copies are made on the surface.

As shown in FIG. 2, the re-feeding section 7 is composed of a carrying roller 21, a paper feeding roller 22 and a separating roller 23. First, the carrying roller 21 is placed on the intermediate tray 6 at the top. It serves to feed the lower paper and feed the sheet to the paper feed roller 22 and the separation roller 23. Next, the separation roller 23 is pressed against the paper feed roller 22 with a clamping force F by a pressing means (not shown), and is supported by the separation roller shaft 24 as shown in FIG. The separation roller shaft 24 is driven in the direction of returning the sheet via a torque limiter 26 between the separation roller shaft 24 and the drive unit.

The torque limiter 26 is constructed by connecting the torque limiter shaft 25 and the body portion 26a with a magnetic body 26b or the like, and the torque applied to the body portion 26a is a predetermined value T.
When it exceeds, the driving force is not transmitted from the torque limiter shaft 25 to the body portion 26a. Therefore, the transmission of the driving force to the separating roller shaft 24 connected to the body portion 26a by the coupling 27 is also cut off,
The separation roller 23 supported by the separation roller shaft 24 is driven by the paper feed roller 22 to rotate in the sheet discharging direction. Here, the paper feed roller 22 and the separation roller 23
The coefficient of friction between the surface of the sheet and the sheet is μ1, the coefficient of friction between the sheets is μ2, the radius of the sheet feeding roller 22 and the separating roller 23 is R, and the weight of the sheet bundle existing on the sheet to be fed is As W,

[0015]

[Formula 1] {(T / μ1 ・ R) + (μ2 / μ1) ・ W)} <F <{(T / μ2 ・ R) -2W} As shown in FIG. 3, when one sheet enters the separating section, the separating roller 23 rotates in the sheet conveying direction, and when two separating sheets enter, as shown in FIG. Sheets can be returned to prevent double feeding of sheets.

In the separating mechanism as described above, when the friction coefficient μ2 between the sheets is relatively large, as shown in FIG. 5, when a plurality of transfer sheets are conveyed to the nip portion n, the transfer sheet is second from the lowest position. The sheet near the leading edge of the sheet always rubs against the developer of the lowest sheet while receiving the nipping force at the nip portion n, so that the sheet near the leading edge of the second sheet from the lowest sheet is soiled. In order to avoid this phenomenon, in the present embodiment, oil is applied to the lower fixing roller 12 by an oil application mechanism described later, the oil is transferred to the transfer sheet to reduce the friction coefficient μ2 between the sheets, and the developer is transferred to another sheet. Is preventing. Further, in order to always carry out this oil application satisfactorily, it has a mechanism for removing paper dust on the surface of the lower fixing roller 12. The mechanism for removing paper dust will be described below with reference to FIG.

FIG. 6 is a sectional view of the fixing device 4 of the present invention. It should be noted that description of common parts with the fixing device described in the conventional example shown in FIG. 8 is omitted, and only different parts will be described.

Reference numeral 100 denotes a paper dust removing unit which is an adhering substance scraping device, and has an adhering substance scraping portion having a structure in which a blade 101 formed of an elastic body is adhered to a resin stay 102. The blade 101 is adapted to abut on the lower fixing roller 12 by a holding means (not shown), and its abutment position is located downstream of the fixing nip portion 18 and upstream of the abutment position of the coating felt 15. ing.

FIG. 7 is a perspective view of the paper dust removing unit 100. As shown in FIG. 7, the width of the blade 101 is set to be slightly wider than the width of the image forming area, and the stay 102 has a paper dust collecting portion 102a having a width slightly wider than the contact width of the blade 101. It is formed as a deposit receiving portion. As described above, in the deposit scraping device of the present invention, the deposit scraping portion and the deposit receiving portion are integrally formed.

In the fixing device of the present embodiment having the above-described structure, the coating felt 15 sucks up the oil 17 in the oil pan 14 by a capillary phenomenon and lowers the fixing roller 12.
Since the fixing roller pair 11 and 12 performs the pre-rotation operation prior to the copying operation, the surface of the lower fixing roller 12 is uniformly coated with oil. Therefore, when the transfer sheet 8 passes through the fixing nip portion 18, the transfer sheet 8 is fixed by heat and pressure and is supplied with oil from the lower fixing roller 12,
Oil is applied to the back side of the surface on which the developer is fixed to reduce the friction coefficient of the back side surface. As a result, it is possible to prevent the occurrence of dirt due to friction between the transfer sheets 8 in the re-feeding unit 7.

However, since fine paper powder is generated on the transfer sheet 8 during the cutting process at the time of manufacturing and the process of being conveyed in the copying machine 1, when the transfer sheet 8 passes through the fixing nip portion 18, the lower fixing roller is used. The paper powder may migrate to 12, which may hinder the oil application.

Therefore, in this embodiment, the paper powder is scraped off from the fixing nip portion 18 by the blade 101 before reaching the point where the coating felt 15 is in contact, so that the oil coating can be performed for a long time. Have been done.

However, the paper dust scraped off in this way falls along the upper surface of the stay 102, and in FIG.
As shown in FIG.
It is necessary to clean or replace the paper powder reservoir 102a. Further, the blade 101 also needs to be cleaned or replaced at any time.

In the prior art, since the blade and the tray were separate, it was possible to forget one of the tasks during such maintenance work. However, according to this embodiment, the blade 101 and Since the stay 102 having the paper dust collecting portion 102a is integrally configured, when the blade 101 and the paper dust collecting portion 102a are attempted to be cleaned during maintenance and inspection after copying a large number of sheets, one of them is forgotten. There is no such thing.

Furthermore, the relationship between the capacity of the paper dust collecting portion 102a and the durable life of the blade 101 is set so that the paper dust collecting portion 102a becomes almost full when copying is performed for the expected life of the blade 101. If set, the blade 101 and the stay 10 are set every time the number of copies reaches a certain number.
Since the paper dust removing unit 100 consisting of 2 need only be replaced, the maintenance work becomes very simple.

Although FIGS. 6 and 7 show an example in which the blade 101 is adhered to the stay 102, it may be separable by screwing the blade 101 to the stay 102. Also in this case, since the blade 101 and the stay 102 are integrally configured as the paper dust removing unit 100, when replacing the blade 101, the blade 101 is exchanged after being taken out of the apparatus body 1 as the paper dust removing unit 100. As a result, the paper dust collecting portion is inspected at the same time and the effect of the present invention is not impaired.

Further, according to this embodiment, it is not necessary to separately provide the paper dust receiving tray 26 as in the conventional example, the mechanism can be made compact, and the cost can be reduced.

[0028]

As described above, according to the present invention,
Since the adhering matter scraping section and the adhering matter receiving section of the adhering matter scraping device are integrally formed, it is not necessary to forget to replace or clean either the adhering matter scraping section or the adhering matter receiving section during maintenance and inspection. Maintenance work can be made easy and reliable. As a result, the attached matter can be scraped off favorably for a long period of time. Further, the mechanism of the adhered substance scraping device can be simplified and downsized, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of a re-feeding unit of the apparatus shown in FIG.

FIG. 3 is a cross-sectional view showing a state in which a plurality of transfer materials have entered the sheet feeding unit of the sheet re-feeding unit of the apparatus shown in FIG.

FIG. 4 is a top view of the re-feeding unit shown in FIG.

FIG. 5 is a cross-sectional view illustrating the occurrence of transfer material stains and image disturbance due to friction between transfer materials in the re-feed unit of the apparatus of FIG.

FIG. 6 is a cross-sectional view showing a schematic configuration of a fixing device of the apparatus shown in FIG.

FIG. 7 is a perspective view showing a schematic configuration of an adhering matter scraping device of the device shown in FIG. 6;

FIG. 8 is a sectional view showing a schematic configuration of a conventional fixing device.

[Explanation of symbols]

 4 Fixing Device 8 Transfer Sheet (Transfer Material) 11 Upper Fixing Roller (Fixing Roller) 12 Lower Fixing Roller (Fixing Roller) 100 Paper Dust Removal Unit (Adherent Scratch Removal Device) 101 Blade (Adherent Scratch Removal Section) 102a Paper dust collecting part (adhesion receiving part)

Claims (4)

[Claims] 1. An unfixed developer image on a transfer material is fixed by having a pair of fixing rollers rotatably arranged in pressure contact with each other and nipping and conveying the transfer material by the fixing roller pair. In the fixing device for fixing, of the pair of fixing rollers, facing the roller that comes into contact with the surface on the back side of the unfixed developer image carrying surface on the transfer material when sandwiching the transfer material,
In an image forming apparatus including a fixing device having an adhering matter scraping device arranged so as to contact the surface of the roller, the adhering matter scraping device has an adhering matter scraping section and an adhering matter receiving section. The image forming apparatus is characterized in that the deposit scraping portion and the deposit receiving portion are integrally formed. 2. The release agent applying means for applying a release agent to the surface of the roller is arranged so as to contact the surface of the roller with which the adherent scraping device abuts. 1. The image forming apparatus according to 1. 3. The contact position of the adhering matter scraping device is on the downstream side of the pressure contact portion of the fixing roller pair in the rotational direction of the roller and is higher than the contact position of the release agent applying means with the roller. The image forming apparatus according to claim 2, wherein the image forming apparatus is set on the upstream side in the rotation direction. 4. The capacity of the adhered matter receiving portion in the adhered matter scraping device is such that the adhered matter is substantially filled when fixing is performed for the number of transfer materials requiring replacement of the adhered matter scraping portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is set to.