JPH04271381A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an equivalent disturbing effect with one image disturbing member of a brush construction which disturbs residual toner to make it a non pattern as with a conventional two piece constitution, to simplify the constitution, and to lower the cost of the image forming device. CONSTITUTION:The image disturbing member 40 is constituted from the brush member 41 where a step e is created on its tip, and a part being abutted to a photosensitive body drum 2 is provided in contact with a step e. Thus, the space of the step e acts as a buffer accumulating the toner T, more or less, and the equivalent disturbing effect is obtained with the one-brush construction image disturbing member 40 as one with the conventional two piece construction, electrifying uneveness or exposure uneveness is prevented, and a bright image formation is carried out without any uneveness in memory or concentration.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic apparatus or an electrostatic printer, and more specifically, the present invention relates to an image forming apparatus such as an electrophotographic apparatus or an electrostatic printer. At the same time, the remaining developer after passing through the transfer section on the image carrier is transferred to the transfer material downstream of the transfer section and in sliding contact with the image carrier. The present invention relates to an image forming apparatus including an image disturbing member that changes the image.

0002

2. Description of the Related Art In recent years, there has been a demand for miniaturization of this type of image forming apparatus.
The publication discloses a method of downsizing the device by using one device as both a developing device and a cleaning device. In this method, one photosensitive drum is used in one developing device.
The electrostatic latent image is developed when passing here for the second time, and then the second
The image is passed through the developing device a second time to clean the residual image after transfer. However, in this conventional method, the residual image is removed when the photosensitive drum passes through the developing device for the second time, so the recording speed is halved and the circumference of the photosensitive drum is removed. There is a problem in that a recording area larger than the entire surface cannot be obtained, and the photosensitive drum must necessarily be relatively large in size, making it impossible to make the device sufficiently small.

On the other hand, US Pat. No. 364,926 discloses that when the electrostatic latent image passes for the first time, the development of the electrostatic latent image and the cleaning of developer remaining after the previous transfer are simultaneously carried out. A method is disclosed that overcomes the speed disadvantage by using a developing device.

However, in this conventional apparatus, the residual image after transfer is left on the photosensitive drum, and the subsequent charging, formation of an electrostatic latent image, and development are performed on the residual image.

[0005] Therefore, in charging, the remaining latent image and toner image are charged overlappingly, and the next image exposure is performed from above this toner image, which impairs uniform charging and formation of the latent image. Since the afterimage of the above process appears as a so-called memory image overlapping the next screen, there is a drawback that the image becomes unclear.

[0006] Such development is particularly likely to occur when a solid part (an area to which developer adheres over a wide range) and a residual image such as a character formed in a previous process encounter each other.
Often, not only the latent image but also the developer cannot be removed sufficiently, so that the developer image remains as an afterimage memory and is transferred as is to the paper. As described above, conventional image forming apparatuses do not have sufficient reliability, and often have a problem in that clear images cannot be obtained.

[0007]Recently, therefore, as a solution to these problems, a method has been developed in which the developer image is placed downstream of a transfer section that transfers a developer image onto a transfer material such as paper and is in sliding contact with the image carrier. An image forming apparatus that is provided with an image disturbing member that non-patterns the remaining developer after passing through a transfer section on an image carrier has been developed and put into practical use. Usually, a brush structure was used as the image disturbing member.

Conventionally, as shown in FIG. 7, as an image disturbing member a having a brush structure, a brush member b made of two brush fabrics is folded in half so that tips b1 and b2 are aligned. It was constructed by folding an aluminum plate B in half, inserting about half of it, and caulking it. The brush portion d is arranged such that the tip side of the abdomen is in sliding contact with the circumferential surface of the photoreceptor drum. Then, by adsorbing or releasing the developer onto the brush portion d, the remaining developer after passing through the transfer section is made into a non-patterned state.

However, if the diameter of the photoreceptor drum is 40
If the diameter is less than mm, it is very difficult to remove the nip.
A sufficient disturbing effect cannot be obtained with one image disturbing member a, and as shown in FIG. 8, two image disturbing members a1 are used, which are brush portions d1 and d2 of different lengths so that a step e is created at the tip.
, a2 were used in combination. Such a configuration has the problem of high cost and takes up space, which is a major bottleneck in miniaturizing the device.

0010

Problems to be Solved by the Invention As described above, in an image forming apparatus provided with an image disturbing member for non-patterning the developer remaining on the image carrier after passing through the transfer section, it is particularly important to When the diameter is small, a plurality of image disturbing members may be stacked and used. For this reason, there have been problems such as high cost and a large installation space, which is an obstacle to miniaturization of the device.

The present invention has been made in view of the above circumstances, and it is possible to obtain a disturbing effect equivalent to that of the conventional two-piece structure with one image disturbing member, and to simplify the structure and reduce costs. The purpose of the present invention is to provide an image forming apparatus that is

0012

[Means for Solving the Problems] In order to solve the above problems, the present invention forms a developer image on an image carrier, transfers this developer image to a transfer material in a transfer section, and In the image forming apparatus, an image-disturbing member is provided on the downstream side of the transfer section and in sliding contact with the image carrier, for non-patterning the developer remaining on the image carrier after passing through the transfer section. The disturbance member is configured to include a brush member having a step at its tip portion that comes into contact with the image carrier.

[0013]

[Function] As described above, in the present invention, since the image disturbing member is constructed by shifting the tip position of the brush member so that a step is created at the tip, the contact portion with the image carrier has a step. By making contact with each other, the gap in the stepped portion acts as a buffer in which some developer is stored. This results in 1
It is possible to obtain the same disturbance effect with one image disturbance member as with the conventional two-piece structure, and it is sufficient to deal with after solid printing and when clearing jams.Moreover, it is possible to simplify the structure and reduce costs. It becomes possible.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an image forming apparatus according to the present invention, in which a photosensitive drum 2 as an image carrier is provided approximately at the center of the apparatus main body 1 so as to be rotatable in the direction of arrow A. There is. This photoreceptor drum 2 is an organic photoreceptor (OPC).
) type photoconductive material, and has a recording area smaller (ie, smaller diameter) than the area of the image to be recorded. In the example, the drum diameter is 40 mm.

Further, as shown in FIG. 3, around the photosensitive drum 2, there are discharging means 3, developer stirring means 4, charging means 5, An electrostatic latent image forming means 6, a developing and cleaning means 7, and a transfer means 8 are provided. An image forming means 9 is configured to form a toner image T' as a developer image on the circumferential surface of the photosensitive drum 2.

Further, in the apparatus main body 1, a paper P as a transfer material taken out from a paper feed cassette 10 disposed at the lower part of the apparatus main body 1 is connected to the photosensitive drum 2 of the image forming means 9. A paper conveyance path 13 is formed which leads to a paper discharge tray 12 disposed on the other side of the apparatus main body 1 via an image transfer section 11 between the image transfer unit 8 and the transfer means 8 .

Furthermore, the image transfer section 1 of the paper conveyance path 13
1, an aligning roller 15 is arranged to align the leading edge of the paper P taken out from the paper feed cassette 10 via the paper feed roller 14, and then feed the paper P to the image transfer unit 11 in a timely manner. . Further, on the upstream side of the image transfer section 11, there is a fixing device 16 for fixing the toner image T' transferred to the paper P, and a paper output tray 12 for transferring the fixed paper P.
A pair of discharge rollers 17 is provided to discharge the paper. Also,
Between the fixing device 16 and the pair of paper discharge rollers 17, the paper P fixed by the fixing device 16 is transferred to a reversing conveyance path 18 as necessary.
A gate 19 is provided that leads to.

The paper P guided to the reversing conveyance path 18 is delivered via a pair of paper ejection rollers 20 to a paper ejection section 21 consisting of a recess formed on the top side of the apparatus main body 1 with the image forming side facing down. The paper is now ejected. Next, the image forming operation according to this embodiment will be explained.

Rotate the photosensitive drum 2 in the direction of arrow A,
The circumferential surface of the photosensitive drum 2 is charged to about -500 to -800 volts by a charging means 5 consisting of a scorotron charger. Subsequently, this charged area is exposed by irradiating a light beam 25 from an electrostatic latent image forming means 6 consisting of an EL (edge emitter array) according to the image information, thereby forming an electrostatic latent image on the surface of the photoreceptor drum 2. Form. The electrostatic latent image is then conveyed to a developing and cleaning position facing the developing and cleaning means 7.

In the developer cleaning means 7, a hopper 26 containing toner T as a so-called one-component developer having triboelectric properties conveys the toner T toward a position facing the photosensitive drum 2, and also transports the toner T toward a position facing the photosensitive drum 2. A developing roller 27 is provided for returning the toner T remaining on the body drum 2 into the hopper 26.

The developing roller 27 has a diameter of 102 to 10.
The conductive surface layer 28 has an electrical resistance of 8 Ω, and the inside thereof is made of foamed urethane, silicone rubber, or EPD.
An elastic layer 29 made of M or the like is arranged to constitute an elastic roller as a whole.

The developing roller 27 includes an elastic blade 30 made of phosphor bronze, urethane, silicone resin, etc., for forming a thin layer while frictionally charging the toner T.
is being pressed. The toner T passing through this area is charged with negative triboelectricity of the same polarity as the photoreceptor drum 2, and becomes one layer to
Form about three toner layers.

[0024] Examples of the material of the surface layer 28 include:
It is formed by applying a mixture of urethane resin and conductive carbon in an amount of 10 to 30 percent. Further, a bias power source (not shown) is connected to the developing roller 27 and is electrically connected to the surface layer 28 . Thereby, a predetermined developing bias is applied during development and cleaning. A sponge-like developer transport roller 31 is provided inside the hopper 26, and plays the role of preventing agglomeration of the toner T within the hopper 26 and transporting and supplying the toner T.

Toner T is sent out from the developing roller 27 of the developing and cleaning device 9, and is applied to the electrostatic latent image elastically and
Due to the deformation, they come into contact with each other with a nip width, and the toner T is attached to form a toner image T'. In this case, the toner T adheres to the light irradiation area, resulting in so-called reversal development. Toner T
is charged to about -5 to -30 μc/g (microcoulombs/gram) due to friction between the blade 30 and the surface layer 28 of the developing roller 27, and the developing roller 27 is charged with about -150 to -450 volts. A voltage is applied. The developed toner image T' is then conveyed to a transfer area facing the transfer means 8 consisting of a transfer roller 22, that is, the image transfer section 11. On the other hand, the paper P taken out from the paper feed unit 10 by the rotation of the paper feed roller 14 is sent to the image transfer section 11 in synchronization with the rotation of the photosensitive drum 2.

A positive bias is applied to the back surface of the paper P by the transfer roller 22, and the toner image T' on the surface of the photosensitive drum 2 is electrostatically attracted to the paper P and transferred. Here, the transfer roller 22 is configured such that a positively biased alternating current bias is applied to the rotating shaft by a power source (not shown), and 5 to 40 percent conductive carbon is mixed into the silicone resin provided at both ends of the transfer roller 22. A voltage is applied to the conductive surface portion of the roller surface of 10 5 to 10 9 Ωcm through the conductive portion formed by the conductive portion.

The surface of the transfer roller 22 is preferably made of a material with smoothness and low friction in order to make it easier to clean foreign matter such as toner T and paper dust that adheres to it. The cleaning blade 32 cleans the cleaning blade 32 effectively. In addition, as for the entire rubber hardness of the transfer roller 22, a flexible one having a rubber hardness of 25 to 50 degrees was found to have a wide tolerance for the pressing force against the photoreceptor drum 2 according to comparative measurements according to the JIS method.

Further, the paper P after the transfer is sent to the fixing device 16, where the toner image T' is melted and fixed on the paper P, and then selectively ejected to the paper ejection tray 12 or the paper ejection section 21. Ru. On the other hand, when the untransferred toner T remaining on the photoreceptor drum 2 after the transfer passes through the charge eliminating means 3, the electrostatic latent image on the photoreceptor drum 2 is largely neutralized.

Further, the developer stirring means 4 includes an image disturbing member 40 having a brush structure, and this image disturbing member 40 is rubbed with the rotation of the photosensitive drum 2, so that the residual toner T after transfer is sufficiently disturbed and non-patterned. be converted into

After the electrostatic latent image is erased in this manner and the residual toner after transfer is made non-patterned, the photosensitive drum 2 is charged to a predetermined potential by the charging means 5 comprising a scorotron charger. At this time, the non-patterned toner T scattered in the form of mist on the photosensitive drum 2 is also negatively charged and cleaned by the developing and cleaning means 7, and the above-described steps are repeated. Next, the configuration of the image disturbing member 40 will be described in detail.

As shown in FIG. 1, the image disturbing member 40 includes a brush member 41 that is folded in half so as to form a step e at its tip, and a holding member 42 that holds this brush member 41.
It consists of. The contact portion with the photoreceptor drum 2 is shown in FIG.
It looks like this.

Since the contact portion with the photosensitive drum 2 comes into contact with the step e, the gap in the step serves as a buffer for storing more or less toner T. It has a great effect on the cleaning action after pattern printing, and when we experimented by changing the distance of the step e, we found that if the step e is 1 mm or more, it is sufficient to cope with after solid printing and when handling jams. It was possible.

[0033] Also, as shown in Fig. 5, how to make it is as shown in Fig. 5.
Two layers of brush fabric 41' made of fibers (trade names: Trading Card, Kynor, etc.) having an electrical resistance of 105 Ωcm) are stacked so that a step e is formed at the tips of the two brush parts 41a and 41b. After folding, it is inserted into an aluminum plate 42', which serves as a holding member 42, which is bent in advance into a V-shape, as shown by the two-dot chain line. Then, as shown in FIG. 6, the aluminum plate 42' is caulked inward.

[0034] Although it is extremely simple and low-cost, it is now possible to achieve the same performance as the conventional two-piece configuration shown in FIG. This is particularly effective for small-diameter photosensitive drums 2. Note that it goes without saying that the present invention is not limited to the one embodiment described above, and can be implemented in various modifications without changing the gist.

[0035]

[Effects of the Invention] As explained above, according to the present invention,
A developer image is formed on the image carrier, and this developer image is transferred to a transfer material in a transfer section, and the image carrier is placed downstream of the transfer section and in sliding contact with the image carrier. In the image forming apparatus, the image-disturbing member is provided with an image-disturbing member that non-patterns the remaining developer after passing through a transfer section on the body, wherein the image-disturbing member has a step at a distal end portion that comes into contact with the image carrier. This configuration includes a brush member.

[0036] Therefore, since the abutting portion of the image disturbing member and the image carrier come into contact with each other with a step, the gap in the step has the role of a buffer for storing more or less developer. As a result, a single image disturbing member can provide the same disturbing effect as the conventional two-piece structure, and can be used to deal with solid printing and jam processing. This has the effect of making it possible to reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an image disturbing member that is a main part of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus that is an embodiment of the present invention.

FIG. 3 is a partially enlarged view of FIG. 2.

FIG. 4 is an explanatory diagram showing a state of a contact portion between an image disturbing member and an image carrier, which is a main part of an embodiment of the present invention.

FIG. 5 is a diagram showing how to construct a developer stirring means in an embodiment of the present invention.

FIG. 6 is a diagram showing how to construct a developer stirring means in an embodiment of the present invention.

FIG. 7 is a diagram showing the configuration of a conventional image disturbing member.

FIG. 8 is a diagram showing a conventional two-layered image disturbing member.

[Explanation of symbols]

2... Photosensitive drum (image carrier), 4... Developer stirring means,
7...Development cleaning means, 11...Transfer section, 40...Image disturbing member,
41'... Brush fabric, 41... Brush member, 42... Aluminum plate (holding member), e... Brush step, T'... Toner image (developer image), T... Toner (developer), P... Paper ( transfer material).

Claims (1)

[Claims] Claim 1: A developer image is formed on an image carrier, and this developer image is transferred to a transfer material in a transfer section, and a developer image is provided on the downstream side of the transfer section and in sliding contact with the image carrier. In the image forming apparatus, the image-disturbing member is provided with an image-disturbing member that non-patterns the remaining developer after passing through the transfer section on the image-bearing member, wherein the image-disturbing member has a step at a tip portion that comes into contact with the image-bearing member. An image forming apparatus characterized in that it is configured to include a brush member having a brush member.