JPH0486880A - Image formation device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention forms an electrostatic latent image on an image bearing member such as a photoconductor, develops this electrostatic latent image, and prints a sheet of paper. The present invention relates to an image forming apparatus that forms an image on a transfer material such as the like.

(Prior Art) As this type of image forming apparatus, electrophotographic apparatuses, electrostatic printers, and the like are known. In these image forming devices,
After forming an electrostatic latent image on the photoconductor, a developer is electrostatically attached to the electrostatic latent image to form a developer image, and then the image is created by transferring the developer image to paper. is formed.

Furthermore, since the electrostatic latent image and developer that has not been transferred remain on the photoconductor after transfer, the remaining developer is removed by a cleaning device, and then the electrostatic latent image is removed by a static eliminator. It is being removed.

Incidentally, in recent years, there has been a demand for downsizing of devices, and for example, Jikai Publication No. 11538/1973 discloses a method of downsizing the device by using one device as a developing device and a cleaning device. ing. In this method, in one developing device, the electrostatic latent image is developed when the photosensitive drum passes through the developing device for the first time, and then the residual image after the transfer is cleaned by passing through the developing device a second time. There is. 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, U.S. Patent No. 364926 discloses a developing device that simultaneously develops the electrostatic latent image and cleans the developer remaining after the previous transfer when the electrostatic latent image passes for the first time. A method is disclosed which overcomes the speed disadvantage by using the following methods.

However, in this conventional apparatus, the residual image after the 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. Therefore, when 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. However, since the afterimage from the above process appears as a so-called memory image overlapping the next screen, there is a drawback that the image becomes unclear. This type of development is particularly likely to occur when a solid area (an area where the developer adheres over a wide area) and a residual image such as a character formed in a previous process meet, and often not only the latent image but also the developer Because the developer image cannot be removed sufficiently, the developer image may also remain as an afterimage memory and be transferred to the paper as is.

(Problems to be Solved by the Invention) As described above, conventional image forming apparatuses have the problem that sufficient reliability cannot be obtained and often clear images cannot be obtained. Furthermore, it has not been possible to make the photosensitive drum used smaller than the recording size.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small-sized image forming apparatus that can obtain clear images.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a latent image forming means for forming a latent image on the surface of an image carrier, and a method for forming a latent image by the latent image forming means. a developer cleaning means for visualizing the latent image formed using a developer and removing the developer remaining on the surface of the image carrier; and a developer cleaning means for removing the developer attached to the surface of the image carrier. a transfer means for transferring onto a transfer material;
In the image forming apparatus, the image forming apparatus includes a disturbance means for disturbing the developer remaining on the surface of the image carrier after the transfer by the transfer means, wherein the disturbance means includes a plurality of stages that are in sliding contact with the image carrier. It is characterized in that the sliding contact surface of at least one sliding contact member is comprised of an uneven portion having a predetermined angle with respect to the rotational direction of the image carrier.

A second invention provides a latent image forming means for forming a latent image on the surface of an image bearing member, a latent image forming means for visualizing the latent image formed by the latent image forming means using a developer, and a surface of the image bearing member. a developer cleaning means for removing residual developer; a transfer means for transferring the developer adhered to the surface of the image carrier onto a transfer material by the developer cleaning means; In an image forming apparatus comprising a disturbance means for disturbing developer remaining on the surface of an image carrier, the disturbance means is composed of a plurality of sliding contact members slidingly contacting the image carrier, and the most downstream The length of the sliding contact member in the rotational direction of the image carrier is longer than the other sliding contact members.

(Function) In the present invention, the disturbance means is composed of a plurality of stages of sliding members that are in sliding contact with the image carrier, and the length of the most downstream sliding member with respect to the rotational direction of the image carrier is longer than that of the other sliding members. Since the length is longer than that, a clear image can be obtained and the device can be made smaller.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 1 shows an image forming apparatus according to the present invention.
At approximately the center of the main body H, a photosensitive drum 1 serving as an image carrier having a recording surface smaller than the area of the image to be recorded (that is, having a small diameter) is rotatably provided in the direction of arrow A. . The photoreceptor drum 1 is an organic photoreceptor (OPC).
The drum diameter is 40r.
It is am.

Further, around the photosensitive drum 1, in order along the rotation direction thereof, a static eliminating means 7, a developer stirring means 2, a scorotron charger 3, an electrostatic latent image forming means 4, a developing cleaning device 5, and a transfer roller 6 are arranged. is installed.

The operation of the electronic copying apparatus according to this embodiment will be explained below. The photoreceptor drum 1 is rotated in the direction of arrow A, and the circumferential surface of the photoreceptor drum 1 is charged approximately -5 by the scorotron charger 3.
Charged to 00 to -800 ■. Subsequently, this charged area is exposed by irradiating a light beam 8 from an electrostatic latent image forming means 4 made of an EL (edge emitter array) according to the image information, thereby forming an electrostatic latent image on the surface of the photoreceptor drum 1. Form.

In one embodiment of the present invention, an EL is used as the electrostatic latent image forming means, but in the present invention, a light source such as a laser, a liquid crystal shutter, or an LED may be used without any problem.

The electrostatic latent image is then conveyed to a developing cleaning position facing the developing cleaning device 5.

The developer cleaning device 5 is provided with a hopper 9 that stores a so-called -component developer T that is triboelectrically charged. A developing roller 10 is provided that transports the developer T remaining on the photoreceptor drum 1 and returns it into the hopper 9 .

The developing roller 10 has an electrically conductive surface layer (not shown) having an electrical resistance of 102 to 108 ohms, and an elastic layer (not shown) made of foamed urethane, silicone rubber, EPDM, etc. disposed inside the surface layer to provide elasticity as a whole. It makes up a certain roller.

The developing roller 10 is triboelectrically charged with the developer T.
An elastic blade 13 made of phosphor bronze, urethane, silicone resin, etc. is pressed to form a thin layer, and the developer T passing through this blade is charged with a negative triboelectric charge of the same polarity as the photoreceptor drum 1. A developer layer of about 3 to 3 layers is formed. The surface of the developing roller 10 needs to be selected in consideration of frictional electrification with the developer T and appropriate elasticity and frictional properties.

The surface layer is formed by applying, for example, a mixture of urethane resin and conductive carbon in an amount of 10 to 30% by weight. Furthermore, a bias power source (not shown) is connected to the developing roller 10 and is electrically connected to the surface layer. Thereby, a predetermined developing bias is applied during development and cleaning. A sponge-like developer conveying roller 15 is provided in the hopper 9, and plays the role of preventing agglomeration of the developer T in the hopper 9 and conveying and supplying the developer T.

A developer (hereinafter referred to as
Toner (referred to as toner) T is sent out, and this contacts the electrostatic latent image elastically and with a nip width due to deformation, and the toner T is attached to form a toner image. In this case, the toner T adheres to the light irradiation area, resulting in so-called reversal development. The toner T is charged to about -5 to -30 μc/g (microcoulombs/gram) due to friction with the surface layer of the blade] 3 and the developing roller 10, and the developing roller 10 is charged with about -150 to -450 μc/g. voltage is applied.

The developed toner image is then conveyed to a transfer area facing the transfer roller 6. On the other hand, there is a paper feed roller 2 in the transfer area.
0 rotation, the paper P is fed from the paper feed unit 19 in synchronization with the rotation of the photosensitive drum 1.

A positive bias is applied to the back surface of the paper P by the transfer roller 6, and the toner image on the surface of the photosensitive drum 1 is electrostatically attracted to the paper P and transferred. Here, a positively biased alternating current bias is applied to the rotating shaft of the transfer roller 6 by a power supply (not shown), and 5 to 40% by weight of conductive carbon is mixed into the silicone resin provided at both ends of the transfer roller 6. A voltage is applied to the conductive surface portion of the roller surface of 10 5 to 10 9 Ω (maximum) through the conductive portion. The surface of the transfer roller 6 is preferably made of a material with a smooth surface and low friction properties in order to make it easier to clean foreign matter such as developer and paper dust that adheres to it. In this example, conductive polyfluoride resin is used. ,
It uses conductive polyester, etc., and can be cleaned well with a cleaning blade. In addition, the rubber hardness of the entire roller is 25 to 50 according to JIS method comparison measurement.
The flexible one had a wide tolerance for the pressing force of the transfer roller 6 against the photoreceptor drum 1 and was good.

Further, the paper P after the transfer is sent to the qualitative device 21, where the toner is melted and fixed on the paper P, and then discharged.

FIG. 2 is an enlarged view of the area around the image carrier in FIG. Most of the static electricity has been removed. The conductive brushes 2a and 2b, which are the developer stirring means 2, are rubbed together with the rotation of the photosensitive drum 1, and the residual toner after transfer is sufficiently disturbed and non-patterned.

In this way, after the electrostatic latent image is erased and the residual toner after transfer is also made non-patterned, the photoreceptor 1 is charged to a predetermined potential by the scorotron 3, which is a charging means. At this time, the non-patterned toner scattered in the form of mist on the image carrier 1 is also negatively charged and cleaned in the developing and cleaning device 5, and the above-described steps are repeated.

Note that the static eliminating means 7 uses a red LED. However, in order to remove the charge on the photoreceptor from the top of the transferred residual toner, a stronger light is required than the amount of light for removing static electricity provided by a normal cleaning device. The amount of light required is approximately 8 to 20 times the amount of light attenuated by half when a static elimination lamp is used as a light source, and the developer stirring means 2 is made of fiber (trade name: Torayca, Kynor, etc.) having an electrical resistance of 103 to 109 Ωl. Brush 2a (hereinafter referred to as brush 2a) is a first image disturbing member and brush 2b (hereinafter referred to as brush 2) is a second image disturbing member.
b), and a brush 2a is arranged on the upstream side so as to be in sliding contact with the photoreceptor drum 1, and a brush 2b is arranged on the downstream side, and the brush 2a has a negative DC bias and the brush 2
A positively biased AC bias is applied to b.

Next, details of the cleanerless process will be explained.

After the transfer, a small amount of the toner image and electrostatic latent image that were not completely transferred remain on the surface of the photoreceptor drum 1. The electrostatic latent image that remains is the red L that is the static eliminating means 7.
It is erased by ED6.

However, since the residual toner after transfer blocks the light, it is necessary to increase the amount of light for static elimination compared to an apparatus having a cleaner.

The amount of light required is eight times or more than the amount of light attenuated by half when the static elimination lamp is used as the light source. Next, the transferred residual toner image is conveyed to the developer stirring means 2 and is made into a non-patterned image. As described above, in the developer stirring means 2, the brush 2a is brought into contact with the toner image and the electrostatic latent image to apply electrostatic and mechanical forces to finely disturb the residual image to the point where it becomes illegible. Therefore, the toner T on the surface of the photosensitive drum 1 after passing through the developer stirring means 2 is distributed in the form of a sufficiently small mist, and no longer contains information as characters or images. In this way, after the transferred residual toner image is sufficiently non-patterned, the process returns to the charging process.

Photosensitive drum 1 charged by Scorotron charger 3
After being charged, it is exposed to light by the electrostatic latent image forming means 4 to form an electrostatic latent image, and reaches the developing cleaning position facing the developing cleaning device 5 again (for the second time). In this case, in the electrostatic latent image formed the second time, the exposed areas (image areas to which toner should adhere) and non-exposed areas (non-image areas) have also been significantly reduced due to roller transfer. almost uniformly,
In addition, although the residual toner is sufficiently thinly scattered, exposure unevenness does not occur. Therefore, even in the second development, the residual potential becomes uniform after exposure, so that a uniform toner image can be obtained. Here, as described above, since the developing roller 10 has an elasticity of 30 to 70 degrees according to the JIS rubber hardness measurement method and a conductivity of 102 to 108 Ω, the linear load on the developing roller 10 is 20 to 150 g/■.
By applying a load of 1.5 to 4 times and making pressure-sliding contact with a speed difference of 1.5 to 4 times, a nip) is generated with a contact width of 1 to 4+n+s, and in this nip, the residual toner and the toner T on the developing roller 10 are Due to the agitated rubbing, a strong frictional force is generated and the cleaning ability is enhanced.

Moreover, since the developer is formed only from toner T,
There are no streaks or flaky deterioration in image quality.

Furthermore, in the non-exposed area, since the suction force due to the developing bias exceeds that of the photosensitive drum 1, the adhered toner T is successively attracted to the developing cleaning device 5 and collected.

That is, by applying a developing bias of an appropriate value between the residual potential of the exposed area and the potential of the non-exposed area to the developing roller 1°, new toner is transferred from the developing roller 10 to the exposed area (as soon as 08 , and at the same time non-image area (non-image part)
The residual toner adhering to the developing roller 10 is then attracted to the developing roller 10 and collected. In this case, the amount of residual toner is small and has already been dispersed in the form of small mist by the developer stirring means 2, so the developer cleaning device 5 can efficiently collect the residual toner without causing collection failures. .

In this way, the photosensitive drum 1 is rotated and used repeatedly to obtain a number of recorded images.

After development and cleaning, the toner image is transferred to the transfer roller 6.
The image is transferred to the paper P at the position facing the . Thereafter, similar steps are repeated.

Good transfer characteristic range operating environment by the transfer roller 6)
is shown with diagonal lines in FIG. 3(a). Bias conditions are DC
+600V, AC1800, 2kHz. Similarly, measurement using a conventional transfer corona is shown in FIG. 2(b). This comparison shows that the transfer roller 6 achieves a transfer efficiency of 85% or more in a relative humidity range of 30 to 85%, whereas the corona transfer method achieves a transfer efficiency of 30 to 50% in a humid environment.
A transfer efficiency of 85% or more can only be obtained within a humidity range of
Further, in a humid environment of 70% or more, the transfer efficiency becomes 60% or less. If the corona transfer method is used in a so-called cleaner-less recording apparatus that does not have a cleaning device, the amount of residual toner increases rapidly under high humidity conditions, placing a large burden on the developer stirring means 2 and the developer cleaning device 5.

An increase in the amount of transferred residual toner means that the amount of toner accumulated in the developer agitation means 2 increases, which may cause staining inside the machine or a decrease in the non-patterning ability of the transferred residual toner.

If the ability of the developer stirring means 2 to not slam the remaining toner after transfer is reduced, a memory of the remaining transfer pattern may occur, and the developer cleaning device 5 may not be able to perform sufficient cleaning.
Fog occurs. Therefore, in a cleanerless recording apparatus, it is desirable to adopt a contact transfer method.

From the above, the contact type transfer using the elastic conductive transfer roller 6 is extremely efficient and reduces residual toner in a wide range of environments.
Since it comes into direct contact with the transfer paper, the paper powder adhering to the paper P is also efficiently adsorbed and removed.
The amount of deposits remaining on the toner is extremely reduced, and no charge reversal of the residual toner after transfer occurs, making it possible to prevent memory generation.

Furthermore, by using the transfer roller 6, the paper P is mechanically pressed, so that transfer failure (partial not being transferred) occurs.
It is possible to transfer a clear image with little effect on the size or quality of the paper.

According to this embodiment, even if the photosensitive drum 1 having a small diameter is used, not only the memory image that has conventionally occurred can be completely eliminated, but also poor cleaning can be prevented.

Next, the effect of superimposing alternating current and direct current on the bias applied to the developer stirring means 2 and the transfer roller 6 will be explained.

After the residual toner is transferred to the brush 2a to which a negative DC bias is applied, the toner whose polarity has partially changed to positive by the transfer roller is adjusted to negative polarity by adsorption, charge injection, and reverse adhesion to the image carrier. Due to the brush 2b to which an AC bias is applied, the untransferred toner is repeatedly transferred and reversely transferred between the brush 2a and the photosensitive drum 1. The surfaces of the brushes 2a and 2b are not uniform and have irregularities, and as shown in FIG. As the photoreceptor drum 1 rotates, the position at which the brush adheres to the photoreceptor drum changes depending on which part of the brush it adheres to during reverse transfer. Therefore, as the transfer and counter-transfer are repeated, the pattern gradually shifts, and patterns such as letters and lines remaining on the transfer are disturbed, and after passing through the developer disturbance means 2, pattern information is lost. There is.

FIG. 5 is a graph showing the relationship between the orientation angle α and the image level, and the image level on the vertical axis of the graph is the overall evaluation level throughout the entire environment in the memory evaluation chart, A graded rating was used. Note that a score of 3 or more was considered an acceptable level, and a score of 4 or more was considered a good level.

From FIG. 5, if the orientation angle α becomes too large, not only will the driving torque of the photoreceptor drum 1 increase, but also a horizontal line will be formed on the image carrier when the toner is reversely transferred from the developer stirring means. 5° to 60° or 16° because it is easy to
0° to -501 preferably 10° to 45'' or -
Good effects were obtained in the range of 10° to -45°.

Furthermore, as shown in FIG. 4, the brush 2b on the downstream side in the direction of movement of the image carrier is longer in the direction perpendicular to the direction of movement of the image carrier than the brush 2a on the upstream side. That is, by ensuring that the toner that has passed through the first image-disturbing member (upstream brush) 2a is received by the second image-disturbing member (downstream brush) 2b, the unpatterned toner remaining after transfer is further prevented. It can be done easily.

In addition, the width and depth of the uneven portion at the contact portion of the developer agitating means 2 with the photoreceptor drum 1 must be larger than the average particle size of the toner, otherwise the toner will be reversely transferred from the developer agitating means. It was found that the position of adhesion to the photoreceptor drum was difficult to shift.

That is, in the brush which is the developer stirring means of one embodiment of the present invention, as shown in FIG. The condition is that it is larger than the particle size, and the average particle radius rt (μm) of the toner and the brush 2a
If the fiber radius of is r (μm), then r>SQR[(r+rt) 2-r2]+rt If we rearrange the above inequality, r>4rt, and the fiber radius of the brush 2a is more than four times the average particle radius of the toner. This was sufficient and agreed with the experimental results.

The effect of the developer stirring means 2 can be achieved only if the polarities of the biases applied to the plurality of brushes are different, that is, not only when an alternating current bias is applied, but also when only a direct current is applied.

Further, it is not necessary that all the plurality of brushes have the directional uneven portion of the developer stirring means 2, and there is no problem as long as there is at least one. Instead of using different phases as shown in FIG. 4, which is an embodiment, it is also possible to use the same phase.

In addition, in one embodiment of the present invention, the developer stirring means 2
Although the first image disturbing member and the second image disturbing member are each composed of one brush, the intention of the present invention is not limited thereto, and the first and second image disturbing members are composed of a plurality of brushes. The image disturbing member may be composed of a brush, and the first and second image disturbing members may be made of different materials.

As described above, by applying a bias having an AC component and using the developer disturbance means 2 having the above-described shape, the transfer and reverse transfer of the untransferred toner are repeatedly caused, and the untransferred toner is removed. Non-patterning can be achieved.

Note that toner transfer and reverse transfer do not occur unless the potential difference between the brush and the photoreceptor drum is 300 V or more, so the peak of the bias waveform is the potential of the image area (that is, the exposed area potential) as shown in FIG. They must take turns against each other. For example, if the surface potential is 1550V and the exposed part potential is 70V, if the DC component is Ov,
The effect can be obtained when AC peak-to-peak is 740V or higher. However, in order to sufficiently de-pattern the residual toner after transfer and prevent the occurrence of image memory,
It is desirable to superimpose a DC bias opposite to the toner polarity so as to cause the toner to be adsorbed, while some of the toner is reversely transferred to the photoreceptor while becoming non-patterned. Therefore, AC plus DC
It is effective to apply a bias that is superimposed on the For example, if the DC component is +200v, the AC will peak to
A good effect can be obtained at a peak voltage of 1140 V or higher.

However, when applying DC bias in ten directions,
Toner tends to accumulate on the brush 2a because it is in the direction of absorbing toner.

Therefore, it is desirable to actively eject toner between sheets, during initialization operations, and during print termination operations. Possible methods for the ejection operation include applying a negative DC bias or applying an AC biased to the negative side between sheets, during an initialization operation, or during a printing end operation.

Furthermore, in order to sufficiently de-pattern the residual image after transfer, it is necessary to perform the reciprocating movement of transfer and countertransfer several times.

Using the brush configured as shown in FIG.
FIG. 7 shows the results of examining the occurrence of image memory by applying C+ 400V and AC 1400V (peak to peak) and changing the frequency from 200H2 to 5kHz.

In addition, the configuration of the brush in the example is that the cloth has a diameter of 20 to 200 mm.
um, a fiber with a resistance value of approximately 105 Ω is sewn onto the cloth,
The structure consists of a brush crimped with an aluminum plate. The protruding length of the brush is about 8 times, and the length is longer at the partial culm that comes into contact with the upstream side of the photoreceptor drum in the rotational direction.

Here, the memory image in the cleanerless process will be explained.

If the transferred residual toner image is not sufficiently non-patterned and is exposed to corona during the charging process, the area with the toner image may also be damaged.
It is charged to 0v.

At this time, the untransferred toner is strongly negatively charged by the charging corona. If this portion of the transferred residual toner image is a non-image area, that is, will not be exposed to light in the next process cycle, it should be removed from the photoreceptor drum 1 by the developer cleaning device 5. However, if there is a large amount of untransferred material and it is not sufficiently non-patterned, it will not be cleaned sufficiently, so that it will be transferred by the transfer means 6, and a black memory pattern will appear on a white background. This is called positive memory.

Furthermore, if a portion of the residual toner remains in an image area such as a solid image or a halftone image, that is, an exposed area in the next process cycle, the residual toner will block exposure, so that the surface potential of the photoreceptor drum 1 will not attenuate. Alternatively, the attenuation is less than the area without transferred residual toner.

When development is performed in this state, the developing electric field is weakened in areas where there is untransferred toner, so that solids and halftones are left out in the form of untransferred toner patterns, and the density becomes low. This is called negative memory.

Negative memory in general (especially for halftones)
is likely to occur.

FIG. 8 shows measurements of the negative memory of a two-dot line in a halftone with an area ratio of 50% by varying the AC frequency. The white area is the halftone density of the non-memory area,
The black color indicates the density of the negative memory portion (all measured with a microdensitometer). The difference between the two is 0.
If it is within 0.05, it is judged to be almost good by visual judgment. As shown by the solid line in FIG. 8, good memory-free images could be obtained at frequencies from approximately 300 Hz to 4 kHz.

The process speed of the embodiment is 72 m/see, and the nip between the brush 2b and the image carrier is approximately 5 m+s, so that transfer and countertransference are repeated approximately 20 times at a frequency of 30011z. In other words, more than 20 metastases
It can be seen that non-patterning of the transfer residue is achieved by performing reverse transfer.

Next, the nip between the brush 2b and the image carrier 1 is set to approximately 2 mm.
1 and conducted a similar test. 4K from about 700Hz
Good memory-free images could be obtained at frequencies of Hz.

Non-patterning of the transferred residual image is achieved by performing transfer/countertransfer of about 23 degrees.

On the other hand, if the frequency is too high, the toner cannot follow changes in the electric field and transfer or countertransfer, and if the frequency exceeds about 4 kHz, the toner remaining after transfer cannot be patterned.

Next, the effect of applying an alternating current bias to the transfer roller will be described. By applying an alternating current bias to the transfer roller, the toner is subjected to an oscillating electric field in the transfer area and is swayed. This increases transfer sensitivity and transfer efficiency. Another effect of applying an alternating current bias as a transfer bias is a reduction in transfer voids.

In the contact type transfer method, if the contact pressure is too large, overpressure at the toner adhesion area tends to cause lines, characters, etc. to be missing in the transfer. As a measure to prevent this voiding, there is a method of dispersing the pressure by microscopically breaking the toner image by increasing the fluidity of the toner or creating a speed difference between the transfer means 6 and the image carrier. It has been devised. When the toner image is swayed by applying an alternating current bias as a transfer bias, an effect equivalent to microscopically destroying the toner image can be obtained. Transfer bias was DC+800V, AC210ov (peak t.

The transfer efficiency (80% at 30 degrees) and the occurrence of hollow characters were examined under the conditions of (peak) and the frequency was varied from 200 Hz to 5 kHz. The appropriate frequency range is [1001
It was 1z to 3.5kllz. The reason for this is the same as the reason mentioned for the brush; the lower the frequency, the fewer times the brush is oscillated and the less effective it is. Furthermore, if the frequency is too high, it will not be possible to follow changes in the electric field, and transfer voids will likely occur.

The transfer nip at this time is approximately 2.5 degrees. Next, a similar experiment was conducted by lowering the hardness of the transfer roller 6 and setting the transfer nip to about 4+U without changing the transfer pressure.

The appropriate frequency range is approximately 400Hz to 3.5kHz.

It has been found that by applying vibrations of 20 cycles or more in the transfer nip, a good image without transfer voids can be obtained.

With the device shown in Fig. 1, brush 2a bias DC-400■,
Brush 2b bias DC+ 400V, AC140
0Vpp1 frequency 2kllz, transfer bias DC+6
0OL A C2100Vpp, frequency 2kllz,
Under the conditions of surface potential -550■ and exposed part potential -70V,
Transfer bias and brush bias are both OFF between sheets.
When we conducted a printing test on 20,000 sheets, good printing was maintained with no transfer defects and no memory images. As described above, by applying an alternating current bias to the developer-disturbing member and non-patterning the untransferred image, it is possible to perform good printing without charging unevenness or memory images.

Furthermore, if the frequency is too high, the toner will not be able to follow changes in the electric field, and if the frequency is too low, sufficient transfer and reverse transfer of toner will not occur between the image bearing member and the image disturbing member, resulting in residual toner remaining after transfer. Non-patterning is not performed sufficiently, resulting in memory image and image unevenness.

In addition, by performing contact transfer, it is possible to perform good transfer even in a humid environment with good transfer efficiency and no transfer failure, and furthermore, by applying an AC bias, the problems of contact transfer method can be avoided. It is also possible to prevent the occurrence of voids in the transfer of characters and line images. The image disturbance means alone is useful for reducing memory images and image unevenness in a cleanerless process, and the above transfer means is useful for increasing transfer efficiency (especially in humid environments) in ordinary recording devices. It is useful for

However, the characteristics of increasing transfer efficiency, not causing transfer omission even in a humid environment, and not causing hollow characters or lines are particularly useful as a transfer means for a cleanerless process, and the image disturbance means described above is useful as a transfer means for a cleanerless process. The effect is tremendous when this and transfer means are used together in a cleanerless process.

In the apparatus shown in Fig. 1, DC-40 is used as the brush 2a bias.
0V, brush 2b bias and DC+ 400V,
A Ct4oovpp, a frequency of 2 kHz is applied, and DC+600 is applied as a transfer roller bias.
V and AC2100Vpp, frequency 2kt (z is applied, photoreceptor surface potential -550■, exposed part potential 70V)
After conducting a print test of 10,000 sheets, good image quality was maintained, with no transfer defects and no unevenness in memory images or halftones.

In the above embodiment, the non-magnetic component development method was used as the most compact example, but the method is not limited to this, and other known magnetic component development methods, fur brush method, cascade method, etc. Needless to say, it is also possible to apply this method to legal matters.

In addition, as an example of the developer-disturbing member, one using a conductive or resistive brush has been described, or the contact portion with the image carrier has unevenness with directionality with respect to the rotational direction of the image carrier. The shape may be a conductive or resistive sheet or roller as shown in Figures 9 and 10, and the material may be sponge, rubber, etc. Any member may be used as long as it has the conductivity or resistance of 100% and slides into contact with the image carrier without applying a bias.

Figure 9 shows a resistance of 10' to 109Ω as a developer-disturbing member.
This is an example in which a conductive sheet 3o (total) is used, and the material used is polyvinylidene fluoride, Teflon, polymer polyethylene, etc., and the sliding contact part with the photoreceptor drum 1 is shown in FIG. It has an uneven portion having the directionality of the orientation angle α as shown.

The uneven portion is as shown in FIG. 2C, and the space Z formed by the photosensitive drum 1 is set larger than the average particle diameter of the toner used as described above. In addition,
Although the shape of the uneven portion in the embodiment shown in the same figure is rectangular, it goes without saying that the shape is not limited to the rectangular shape but may be circular, sinusoidal, etc., as intended by the present invention.

FIG. 10 shows resistors 103 to 109 as developer disturbing members.
This is an example using a conductive roller 31 marked with Ω, and the material used is a foamed material made of polyurethane, polycarbonate, etc., or a foamed material whose surface is covered with the conductive sheet shown in FIG. 9 above. The roller has a spiral groove with a lead angle α on its surface.

The groove portion is shaped as shown in FIG. 2C, and is composed of the photosensitive drum 1. As described above, the space Z is set to be larger than the average particle diameter of the toner used.

In one embodiment of the present invention, a conductive or resistive brush is used as the image disturbing means, and the free end is disposed on the downstream side (WITI+) with respect to the rotational direction of the image carrier.
It goes without saying that even if it is placed in the AGAINST), the intended purpose of the present invention will not be affected equally.

Further, the transfer means may have a configuration in which an AC bias is applied to a conductive or resistive member such as a transfer belt or a transfer bar in addition to the transfer roller.

[Effects of the Invention] As described above, according to the present invention, the disturbance means includes a plurality of sliding members that slide in sliding contact with the image carrier, and the rotational direction of the image carrier of the most downstream sliding member Since the length of the sliding contact member is longer than that of other sliding contact members, a clear image can be obtained and the device can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an image forming apparatus that is an embodiment of the present invention, FIG. 2 is an enlarged view of the area around the image carrier in FIG. 1, and FIG. 3(a) is a characteristic of roller transfer. The graph showing the characteristics of corona transfer, m(b) is the fourth graph showing the characteristics of corona transfer.
The figure shows an embodiment of the developer image disturbing means of the present invention, FIG. 5 is a graph showing the relationship between the orientation angle α of the developer image disturbing means and the image level, and FIG. An enlarged view of the contact portion of the developer image disturbing means with the image carrier, FIG. 7 is an example of a method of dividing the resistors and applying a class 28 bias using a common power supply, and FIG. 8 is an example of the memory removal effect of the brush. FIG. 9(a) is an embodiment of the sheet-like developer image disturbing means in the present invention, FIG. 9(b) is a detailed diagram of the sheet-like developer image disturbing means, and FIG. 9(c) is a graph showing the frequency effect of ) is an enlarged view of the contact portion of the sheet-like developer image disturbing means with the image carrier; FIG.
(a) is an embodiment of the roller-shaped developer image disturbance means in the present invention; (b) is a detailed view of the roller-shaped developer image disturbance means; (c) is an example of the roller-shaped developer image disturbance means. FIG. 3 is an enlarged view of a contact portion with an image carrier. 1... Photosensitive drum (image carrier) 2...
......Developer image disturbance means 2a...First
Image disturbing member 2b...Second image disturbing member 5...Developer cleaning device 6...Transfer roller Applicant Toshiba Corporation Attorney Patent attorney Mr. Suyama Sasou--g Figure 4 Awatori Netzheng? +15° ±Father° 945″ 9ω″ 775 j
Figure 5 Figure 8

Claims (2)

[Claims] (1) A latent image forming means for forming a latent image on the surface of the image carrier, and a latent image forming means for visualizing the latent image formed by the latent image forming means using a developer and remaining on the surface of the image carrier. a developer cleaning means for removing the developer; a transfer means for transferring the developer attached to the surface of the image carrier by the developer cleaning means to a transfer material; an image forming apparatus comprising a disturbance means for disturbing developer remaining on the surface of the image carrier, the disturbance means comprising a plurality of sliding members in sliding contact with the image carrier, and at least one sliding member. An image forming apparatus characterized in that the sliding surface of the image forming apparatus comprises an uneven portion having a predetermined angle with respect to the rotational direction of the image carrier. (2) A latent image forming means that forms a latent image on the surface of the image carrier, and a developer that visualizes the latent image formed by the latent image forming means and that remains on the surface of the image carrier. a developer cleaning means for removing the developer; a transfer means for transferring the developer attached to the surface of the image carrier by the developer cleaning means to a transfer material; an image forming apparatus comprising a disturbance means for disturbing the developer remaining on the surface of the image carrier, the disturbance means comprising a plurality of sliding contact members slidingly contacting the image carrier, and the most downstream sliding contact member An image forming apparatus characterized in that the length of the image carrier in the rotational direction is longer than other sliding contact members.