JPH0486884A - Recording device - Google Patents

Abstract

PURPOSE:To improve the cleaning efficiency of a remaining developer and to reduce the generation of a density irregularity and a memory image by employing a contact transfer system and reducing a transfer remaining developer, and separating the developer remaining on an image carrier temporarily and then returning it to the image carrier. CONSTITUTION:A photosensitive drum 1 rotates as shown by an arrow A and is charged electrostatically and this electrostatically charged area is exposed to a laser beam 8 to form an electrostatic latent image. Toner T which is sent out of a developing roller 11 to form a toner image by reversal development and the image is conveyed to a transfer area. A form P, on the other hand, is sent to the transfer area and a transfer roller 6 transfers the toner image. The toner image and electrostatic latent image remain on the surface of the drum 1 after transfer and are conveyed to a developer temporary peeling means 2. The brush 2a of the peeling means 2 is applied with a bias voltage and the transfer remaining toner is temporarily attracted. This toner returns to the drum 1 in the time corresponding to the conditions of the resistance of the brush 2a, the particle size of the toner, etc., but the time up to the return is distributed widely to some extent and the toner is made unpatterned. The returned toner becomes minus when the drum 1 is charged electrostatically, and cleaned by a development cleaning device 5.

Description

Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) The present invention forms an electrostatic latent image on an image bearing member such as a photoreceptor, develops this electrostatic latent image, and prints it on a sheet of paper. The present invention relates to a recording device that records on a transfer material such as.

(Prior Art) As this type of recording device, electrophotographic devices, electrostatic printers, and the like are known. In these recording devices, after forming an electrostatic latent image on a photoreceptor, a developer is electrostatically attached to the electrostatic latent image to form a developer image, and then the developer image is transferred to paper. It is recorded by transcription.

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, Japanese Patent Laid-Open No. 115-115 (8) discloses a method of downsizing the device by using a single device as both a developing device and a cleaning device. In this method, an electrostatic latent image is developed in one developing device when the photosensitive drum passes through it for the first time, and then an electrostatic latent image is developed after the transfer by passing through the developing device a second time. The remaining image is being cleaned.

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 that a recording area larger than the size of the entire surface cannot be obtained, and the photosensitive drum inevitably has to be relatively large in size, making it impossible to make the device sufficiently small.

On the other hand, U.S. Pat. A method is disclosed which overcomes the speed disadvantage by using the following methods.

Therefore, in order to solve these problems, a temporary developer stripping means is arranged between the transfer process and the charging process, and after the residual developer is separated from the image carrier, it is returned to the image carrier. A method for downsizing the image carrier and printing at high speed by forming an electrostatic latent image after erasing the pattern of untransferred toner, and cleaning it with a development and cleaning device at the same time as development. is proposed.

(Problem to be Solved by the Invention) However, in this conventional device, the residual image after transfer is left on the photosensitive drum, and then the next charging, formation of an electrostatic latent image, and development are performed on the residual image. become. 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 especially dangerous when solid areas (areas where the developer adheres over a wide area) and residual images such as characters formed in the previous process are encountered, and often not only the latent image but also the developed Since the developer cannot be removed sufficiently, the developer image may also remain as an afterimage memory and be transferred to the paper as is. As described above, conventional recording 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 compact recording device that can obtain clear images.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention provides an electrostatic latent image forming means for forming an electrostatic latent image on an image bearing member, and an electrostatic latent image forming means for forming an electrostatic latent image on an image bearing member. a development cleaning means for removing the developer remaining on the image carrier while supplying a developer charged to the same polarity as the electrostatic latent image formed by the forming means and performing reversal development; and the development cleaning means. A transfer means for transferring a developer image formed on the image carrier by means to a transfer member; and a transfer means that slides into contact with the untransferred developer remaining on the image carrier after the transfer process by the transfer means, and a bias is applied. and a developer temporary stripping means that temporarily separates the transfer residual developer from the image carrier by applying a voltage thereto, and causes the developer to adhere to the image carrier again after a predetermined period of time has elapsed. It is a recording device.

(Function) The developer remaining on the image bearing member is temporarily peeled off by the developer temporary peeling means and then returned to the image bearing member, thereby eliminating the residual toner after transfer and thereby reducing exposure unevenness. In addition to preventing this, the cleaning efficiency of residual developer is improved.

Further, by reliably returning the peeled developer to the image carrier, it is possible to prevent the developer from accumulating in the temporary developer peeling means, thereby extending the life of the apparatus.

By adopting the contact transfer method as the transfer means,
By preventing transfer omission and achieving stable transfer without deterioration of transfer efficiency even in a humid environment, it reduces the amount of developer remaining on the image carrier. By temporarily peeling off the developer and then returning it to the image bearing member, the remaining toner after transfer is removed, thereby preventing uneven exposure and improving the cleaning efficiency of the remaining developer. It is possible to reduce density unevenness and the occurrence of memory images, achieving higher image quality and longer life of the device.

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

FIG. 1 shows a recording apparatus according to the present invention, in which a recording surface smaller than the area of the image to be recorded (that is, a small diameter) is provided as an image carrier approximately at the center of the main body H. A photosensitive drum 1 is provided rotatably in the direction of arrow A. The photoreceptor drum 1 is made of an organic photoreceptor (OPC) type photoconductive material. Further, around the photosensitive drum 1, a temporary developer stripping means 2, a static eliminating means 7, a scorotron charger 3, a laser device 4, a developer cleaning device 5, and a transfer roller 6 are arranged.

The developer temporary stripping means 2 is made of fibers (trade name: Torayca, Kynor, etc.) having an electrical resistance of 103 to 109 Ωcm.
The brush 2a is arranged to be in sliding contact with the photosensitive drum 1, and a voltage of +300 to 100 OV is applied thereto.

Further, the scorotron charger 3 is configured to negatively charge the surface of the photoreceptor drum 1 approximately uniformly to -450 to -800V.

The laser device 3 forms an electrostatic latent image on the charged area on which the surface of the photoreceptor drum 1 has been irradiated with the laser beam 8, depending on the image information to be recorded.

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

The developing roller 10 includes a conductive surface layer 11 having an electrical resistance of 102 to 108 Ω, and an elastic layer 1 made of foamed urethane, silicone rubber, EPDM, etc. inside the conductive surface layer 11.
2 are arranged to form a resilient roller as a whole.

The developing roller 10 is triboelectrically charged with the developer T.
An elastic plate 3 made of phosphor bronze, urethane, silicone resin, etc. is pressed to form a thin layer, and the developer T passing through this plate is charged with a negative frictional charge of the same polarity as the photoreceptor drum 1. One to three developer layers are 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 material for the above surface layer 1 is, for example, a mixture of urethane resin and conductive carbon in an amount of 10 to 30% by weight. Further, a bias power source 14 is connected to the developing roller 10, and the surface layer 1
It is conducting with 1. Thereby, a predetermined developing bias is applied during development and cleaning. A sponge-like developer conveying roller 15 is provided inside the hopper 9.
It plays the role of preventing agglomeration of the developer T inside and transporting and supplying it.

The transfer roller 6 is provided substantially below the photoreceptor tram 1 so as to face the circumferential surface of the photoreceptor drum 1 via the paper conveyance path]6. The above transfer roller 6
has the same structure as the developing roller 10, but the surface layer 11
The electrical resistance of is in the range of 105 to 10'Ω. This transfer roller 6 transfers 60
A voltage of 0 to 2000 V is applied to electrostatically attract the toner, and the toner image is transferred from the photosensitive drum 1 to the paper. This voltage is supplied by a power supply 23.

This type of contact transfer means exhibits stable transfer characteristics even under high humidity conditions, so it is effective in reducing the amount of developer remaining after transfer and reducing the burden of cleaning, as well as reducing the amount of paper dust in the transfer paper. Remove it and prevent it from getting mixed into the developer.

The conductive blank 2a of the developer temporary stripping means 2 is rubbed by the rotation of the photoreceptor tram 1, and is connected to the bias power supply 23 to apply a voltage of 300 to 1500 V to remove the transferred residual developer on the photoreceptor tram 1. Temporarily absorbed. Since most of the transferred residual toner has negative polarity, it is absorbed into the developer temporary stripping means 2, but some of the transferred residual toner, which is fogged toner, is charged to the brush, and these toners are absorbed. Although it passes through without being absorbed, it is not a problem as it is a small amount.

The transferred residual toner temporarily trapped in the temporary developer stripping means 2 is injected with positive charge for a period of time depending on conditions such as the applied bias, the resistance of the blank 2a, the particle size of the toner, and the resistance. The electric field formed by the brush 2a and the photosensitive drum 1 returns the light to the photosensitive drum 1. As mentioned above, the time it takes for the residual toner to be trapped by the temporary developer stripping means 2 until it is returned to the photoreceptor drum 1 after receiving charge injection depends on the toner particle size, resistance, etc. It will have a wide distribution. Therefore, the residual toner after transfer is non-battered. Further, the mechanical sweeping effect of the brush 2a also contributes to the non-bumping of the residual toner after transfer.

The toner returned to the photoreceptor drum 1 has a positive polarity that is opposite to the normal polarity, but when the photoreceptor drum 1 is charged by the scorotron charger 3, it is exposed to negative corona and the toner also has a negative polarity. Then, it is cleaned in the developing and cleaning device 5.

The time t during which the transferred residual toner is trapped in the temporary developer stripping means 2 varies depending on the resistance of the brush, the applied voltage, etc., as described above. When this time t becomes on the order of several seconds or more, toner accumulates on the brush 2a and scatters, causing dirt inside the machine, or a large amount of toner suddenly returns to the photoconductor, causing a line-shaped memory in the longitudinal direction of the photoconductor. or cause it to occur. These phenomena occur when the resistance of the brush 2a is large. Furthermore, if the resistance of the brush is too low, bias will leak to the photoreceptor drum 1, causing damage to the photoreceptor. Therefore, the resistance of the brush 2a is 103 to 10
A 9Ω resistor is preferable. In addition, the applied voltage was 30
It is desirable that it is 0-1500V.

Further, the photosensitive drum 1 is also positively charged by the brush 2a, but the potential at this time varies depending on the amount of untransferred toner, etc., so it is preferable that the charging device is a scorotron charger as in this embodiment. .

In this way, since the residual toner after transfer is trapped and swept out in a short cycle, the amount of toner remaining on the brush 2a is very small. However, when printing is performed continuously, the amount of trapped toner gradually accumulates, and when it exceeds the allowable amount, it is possible that the toner will scatter. Therefore, by arranging the developer temporary stripping means 2 above the photoreceptor drum 1, or from above toward the developing device, the developer T adhering to the brush 2a can be prevented from falling and scattering into the machine. Prevented. That is, there is an advantage that even if the toner falls onto the photoreceptor drum 1, it is transported and recovered as is to the developing and cleaning device 5.

Further, a paper feed unit 19 is provided below the photosensitive drum 1 for supplying the paper P to the transport path 16 . This paper feeding unit 19 stores a paper P to which an image is to be transferred. A paper feed roller 20 that rotates to feed paper P from the paper feed unit 19 to the conveyance path 16 is provided above one of the paper feed units.

Note that the conveying path 16 is provided with a fixing device 21 that fixes the toner image transferred to the paper P.

(The following is a blank space.) Next, the operation of the electronic copying apparatus according to this embodiment will be described.

The photoreceptor drum 1 is rotated in the direction of arrow A, and the circumferential surface of the photoreceptor drum 1 is charged approximately -500 to 8 by the scorotron charger 3.
Charged to 00■. Subsequently, this charged area is exposed by irradiating a laser beam 8 from the laser device 4 to form an electrostatic latent image on the surface of the photoreceptor drum 1. The electrostatic latent image is then conveyed to a developing cleaning position facing the developing cleaning device 5.

A developer (toner) T is sent out from the developing roller 11 of the developing cleaning device 5, and this 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. In this case, the toner T adheres to the light irradiation area, resulting in so-called reversal development. The toner T has a temperature of about -5 to -30 μC/Z (microcoulomb/
gram), and the developing roller 10 has a charge of approximately -1
A voltage of 50 to 450 μ 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.

The back surface of the paper P is charged to a positive polarity by the transfer roller 6. Therefore, the toner image on the surface of the photosensitive drum 1 is electrostatically attracted to the paper P and transferred. Here, the transfer roller 6 is provided with a voltage of 600 to 2000 V to the rotating shaft by a DC power source 23, and is a conductive material made of a silicone resin provided at both ends of the transfer roller 6 mixed with 5 to 40% by weight of conductive carbon. A voltage is applied to the conductive surface portion of the roller surface having a resistance of 10 5 to 10 9 Ω. 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. , conductive polyester, etc., and can be cleaned well with a cleaning blade.

In addition, as for the rubber hardness of the entire roller, a flexible one having a rubber hardness of 25 to 50 degrees was found to have a wide tolerance of the pressing force of the transfer roller 6 against the photoreceptor drum 1 according to a comparative measurement using the JIS method. The range of good transfer characteristics (operating environment) by this transfer roller 6 is shown with diagonal lines in FIG. 2(a).

Similarly, measurement using a conventional transfer corona is shown in FIG. 2(b). According to this comparison, according to the transfer roller 6, a transfer efficiency of 85% or more can be obtained only in a humidity range of 85% in a relative humidity range of 30 to 85%, and a transfer efficiency of 85% or more can be obtained only in a humidity range of 85%.
In the above humid environment, the transfer efficiency would be less than 6 (1%).

This means that in a recording device that does not have a cleaning device like the present invention, the amount of residual toner after transfer increases rapidly in high humidity conditions, and this is due to poor cleaning in so-called cleanerless recording devices that do not have a cleaning device in the past. It was the biggest cause.

In addition, in the corona transfer method, transfer is performed by applying an electric charge to the transfer material, so when transferring to a transfer material with low resistance or to paper in a humid environment, the charge may pass through the transfer layer (leakage). The remaining toner after transfer (called electric charge) becomes positively charged.

As described above, the transfer residual toner of negative polarity is non-battered by the temporary developer stripping means 2, but the positive donor is not trapped and redeposited. Therefore, since the non-bumping process is carried out only by being disturbed by mechanical force, if a positive charge is applied to the transfer remaining toner in the transfer process, a memory image is likely to occur.

On the other hand, in the roller transfer method, charge is partially applied to the transfer material, or the toner is mainly transferred by an electric field formed between the transfer roller 6 and the photoreceptor drum 1, and a positive charge is applied to the toner. Since the charge is only slightly applied, the image is easily unbattered by the temporary developer stripping means 2, and no memory is generated.

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, and since it directly contacts the transfer paper during transfer, the paper Since the paper powder adhering to the toner is efficiently adsorbed and removed, the amount of attached matter remaining on the photoreceptor drum 1 after transfer is extremely reduced, and the charge reversal of the toner remaining after transfer is also prevented, thereby preventing the occurrence of memory. I can do it.

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 and quality of the paper.

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

Incidentally, after the transfer, a toner image and a still image 15 remain on the surface of the photoreceptor drum 1 because they were not completely transferred. These toner images and electrostatic wars are conveyed to the developer temporary stripping means 2 and are de-battered. The temporary developer stripping means 2 brings the brush 2a into contact with the toner image and the static mW image and applies electrostatic and mechanical force to remove the fine particles that remain, as described above, to the point where they are illegible. Disturb the image.

The toner T scattered on the surface of the photoreceptor drum 1 is distributed in the form of a sufficiently small mist and no longer contains information as a character or image. The electrostatic latent image remaining on the photoreceptor is
The charge is erased by the charge eliminating means (for example, a red LED), and the process returns to the charging step.

Photosensitive drum 1 charged by Scorotron charger 3
After being charged, it is exposed to light by the laser device 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. Since the residual toner is scattered almost uniformly and thinly enough, 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 mentioned above, the developing roller 11 is
S rubber hardness lpj has an elasticity of 30 to 70 degrees according to the standard method, and has an electrical conductivity of 112 to 108, so a load of 20 to 150 g/cm as a line load is applied to the developing roller 10, and a linear load of 1.5 to 4 By press-sliding contact with twice the speed difference, a bump) is generated in the contact width of 1 to 4 cm, and in this nip, the residual toner and the toner T on the developing roller 10 are agitated and rubbed, resulting in strong Frictional force is generated and cleaning ability is enhanced. Moreover, since the developer is formed by adding toner T, there is no deterioration in image quality such as streaks or brush marks.

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 10, new toner is attached to the exposed area from the developing roller 10, and At the same time, non-image area (non-image area)
The residual toner adhering to the developing roller 10 is then attracted to the developing roller 10 and collected. In this case, since the residual toner is small and has already been dispersed in the form of a small mist in the temporary developer stripping means 2, the developer cleaning device 5 can efficiently collect the residual toner and prevent collection failures. Never. In this way, the photoreceptor drum 1 is used redundantly,
- Obtain two recorded images.

In addition, as a transfer method, the transfer roller 6 is used as in the embodiment.
Although it is preferable to use the corona transfer method, there is no problem in practical use.

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.

According to this embodiment, even if a photoreceptor tram 1 with a small diameter is used, not only the occurrence of memory images that conventionally occur can be eliminated, but also poor cleaning can be prevented. In this example, when 20,000 sheets of A4 size paper were printed with an image area ratio of approximately 7%, good images could be obtained to the end without any cleaning defects.

Further, in the embodiment, a DC bias having a polarity opposite to that of the toner is applied to the developer temporary stripping means 2. The residual toner after transfer can be unbattered only in the image area, but the bias may be turned off in the area between the images, that is, in the area between the sheets, since there is no patterned image. Further, although much of the toner trapped by the brush 2a re-adheres to the photoreceptor drum 1, it is conceivable that some of the toner cannot completely re-adhere and gradually accumulates on the brush 2a.

Therefore, a bias may be applied to actively sweep out the accumulated toner between the sheets.

For example, it is also effective to apply a bias of about -200 to -1200 V with the opposite polarity to the bias applied to the image area between sheets, or to turn the bias ON/OFF in small increments. In the embodiment, the bias is set to 0N10FF at a period of about 50 msec to 1 sec at the paper interval. In this way, by discharging the toner trapped on the brush 2a between the sheets, excessive accumulation of toner on the brush 2a is prevented. The discharged toner is transferred to the photosensitive drum 1 by the developing cleaning device 5.
removed.

Further, the sweep-out process may be performed at the time of the initializing operation or the finishing operation of printing. During these operations, by turning on the bias of the Scotron charger 3 and the developer cleaning device 5 and applying a bias of about -200 to 12 f) OV to the developer temporary stripping means 2, the toner accumulated in the blank 2a is sufficiently removed. Can be discharged.

Moreover, most of the toner accumulated in the blank 2a has not been injected with charge by the blank and has a normal negative polarity, so it is easier to sweep out the toner when the potential of the photoreceptor is positive. Therefore, when using the corona transfer method, when sweeping out the toner in the initialization and termination operations, even if the transfer corona is turned on and the brush bias is turned off, or a brush bias of -500V or less is applied, A sufficient discharge effect can be obtained.

Next, an example will be described in which the bias applied to the developer temporary stripping means 2 is a combination of alternating current and direct current.

As for the applied voltage, the DC component is 1800V to +800V
.

AC component is 800V to 2000V peak to peak
The applied voltage was used. In addition, the frequency of AC is 300
Good results were obtained with 1 (2 to 4 kl+z). Since an alternating current is superimposed on the bias, the untransferred toner repeats transfer and countertransfer between the brush 2a and the photoreceptor drum.

Unlike rollers and the like, the surface of the brush is not uniform, so its position changes slightly as the photoreceptor drum 1 rotates, and depending on which part of the plan it is attached to, the photoreceptor may be affected during reverse transfer. The position where it attaches to the drum changes. Therefore, as the transfer and counter-transfer are repeated, the pattern gradually shifts, the remaining transferred patterns such as characters and lines are disturbed, and after the developer passes through the temporary developer stripping means 2, the button information is lost. ing.

As described above, by applying a bias having an AC component, it is possible to repeatedly cause the transfer and reverse transfer of the transfer remaining toner, thereby achieving non-bumping of the transfer remaining toner. 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 Figure 3. They must take turns against each other. For example, when the surface potential is 1,550 square meters and the exposed part potential is 170 V, and the DC component is 0 square meters, the effect can be obtained when the AC peak-to-peak is 740 square meters or more.

However, in order to sufficiently debatter the residual toner remaining after transfer and prevent the occurrence of image memory, it is necessary to superimpose a DC bias opposite to the toner polarity to attract the toner, while some of the toner is debattered and transferred to the photoreceptor. It is desirable to reverse transfer to. Therefore, it is effective to apply a bias in which positive DC is superimposed on AC. For example, if the DC component is +
For 200v, AC is 1140cm peak to peak.
Good effects can be obtained in the above manner.

However, when applying a DC bias in the child direction,
Toner tends to accumulate on the brush 2a because the brush 2a is oriented in a direction that attracts toner. Therefore, it is desirable to actively eject toner during the paper interval, initialization operation, and print end operation as described above. In addition, in order to sufficiently unbatter the residual image after transfer, it is necessary to perform the reciprocating movement of transfer and countertransfer several times.

Figure 4 shows the configuration of the brush 2a. Using this brush, DC+300V and AC1400V are connected.
(peak to peak) and set the frequency to 2001
FIG. 5 shows the results of investigating the occurrence of image memory by changing the frequency from 1Z to 5kHz. In addition, the configuration of the brush in the example is cloth with a diameter of 20 to 200 um and a resistance value of approximately 105 Ω・c.
M fibers 31 are sewn onto cloth 32, and then attached to aluminum plate 3.
It has a structure that forms a brush crimped with 3. The projecting length of the plan is about 8 degrees, and the length is longer at the partial culm that comes into contact with the rotation upstream of the photoreceptor drum. Also, the width of the brush is about 5 degrees.

Here, the memory image in the cleanerless process will be explained. If the transferred residual toner image is not sufficiently debatified and is exposed to corona during the charging process, the portions where there is no toner image will be charged to -550 cm. At this time,
The untransferred toner is strongly negatively charged by the charged corona. If this portion of the transferred residual toner image is a non-image portion, 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 cleaner 5. However, if there is a large amount of untransferred material and it has not been sufficiently unbattered, it will not be sufficiently cleaned and will be transferred by the transfer means, resulting in a black memory pattern appearing on a white background. This is called positive memory.

Furthermore, if a portion of the residual toner after transfer is an image area such as a solid image or a halftone, that is, an exposed area in the next process cycle, the surface potential of the photoreceptor drum 1 will not attenuate because the residual toner will block the exposure. . 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 omitted 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. 5 shows measurements of a negative memory with two dot lines in a halftone with an area ratio of 50% while changing the AC frequency. The white areas indicate the normal tone density in the non-memory area, and the black areas indicate the density in the negative memory area (both measured with a microdecitometer).

If the difference between the two is within 0.05 in terms of density difference, it is determined by visual inspection that it is almost good.

As shown in Figure 5, approximately 30OH2 to 4kltz
Good memory-free images could be obtained at frequencies up to. The process speed of the example is 72 m1/se
c.

Since the width of the plan is about 5 mi, the transition and countertransition are repeated about 20 times at a frequency of 300 Hz. Therefore, it can be seen that by performing transfer/countertransference 20 times or more, non-batteryization of the transcription residue is achieved. Furthermore, if the frequency is too high, the toner cannot follow changes in the electric field and cannot perform transfer or countertransference. Therefore, at a frequency exceeding approximately 4°, it is not possible to debatter the residual toner after transfer.

From the above, the appropriate frequency range is 30011z ~
It is 4kllz. Using the brush shown in Fig. 4 and the apparatus shown in Fig. 1, brush bias DC+ 200V, A C1
500Vl)Ill, frequency 2kllz, surface potential -
550■, and the exposed part potential is 70V, the paper distance is DC
When a printing test was carried out on 20,000 sheets with the component changed to -200V, good printing was maintained.

Furthermore, when implementing this embodiment in a digital PPC or the like and performing gradation processing such as pulse width modulation, the potential of the exposed part is -
It changes continuously from 70V to -550V, and in order to cause transfer/reverse transfer with the transferred residual toner at each potential portion, a negative DC bias must be superimposed. If the conditions shown in FIG. 3 are to be met by superimposing a DC bias of 10, a high AC bias must be used.

However, if the AC peak-to-peak exceeds 250 DV, leakage to the photoreceptor drum will occur and the photoreceptor drum will be damaged. Therefore, very small + or - DC
A bias will be applied, but this will not be as effective as when ten DC biases are superimposed.

Therefore, it is desirable to provide a static elimination lamp between the developer temporary stripping means 2 and the transfer process to eliminate the potential of the photoreceptor. In reality, it is not possible to completely eliminate the charge because there is toner remaining after transfer, but it is sufficiently effective.

In the printer configured as shown in Figure 6, the transfer efficiency when the photoconductor potential is changed from about -70V to -500V by pulse width modulation, and the static elimination lamp (red LED, about 15% of the photoconductor's half-light intensity) FIG. 7 shows the change in potential after passing (double the amount of light). It can be seen that the potential is attenuated to 1150 V or less under all conditions.

Therefore, even if ten DC bias components are applied, a small A
The effect is obtained with the C component, DC component +200■, AC component 1.5KV C, peak to peak), frequency 2kl
Even when 20,000 sheets were printed by applying a bias of 1z, no dirt was generated inside the machine, and good images without memory images could be obtained.

As explained above, by attaching the residual toner to the developer temporary peeling means 2 and then re-adhering it to the photoreceptor, the residual image can be made non-battery.
Good images without uneven charging or memory images can be obtained.

In the case of applying a bias or a DC bias, the toner is made to adhere to the brush 2a by the electric field and then redeposited to the photoreceptor by charge injection. At this time, the pattern is disturbed because the timing of re-deposition differs due to variations in the particle size and charge amount of the toner. Also, AC bias or AC and D
When a bias with C superimposed thereon is applied, the pattern is gradually disturbed as the toner repeatedly transfers and reversely transfers between the brush 2a and the photoreceptor drum 1 due to changes in the electric field. In this way, the effect of arranging the static eliminating means 7 before the developer temporary stripping means 2 is the same in a binary printer. Furthermore, the arrangement does not have to be between the transfer means 6 and the temporary developer stripping means 2, but may be between the developer cleaning device 6 and the temporary developer stripping means 2.

Although the embodiment has been described using the transfer roller 6, the function is the same even if it is transformed into a belt shape as a non-corona transfer type contact transfer means. Further, as described above, the same effect can be obtained by using corona charging or the like, so the present invention can be applied regardless of the transfer method.

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 brush methods, fur brush methods, and cascade methods are also available. Needless to say, it is also possible to apply this method to legal matters.

In addition, as an example of the developer temporary stripping means 2, an example using a conductive or resistive brush has been described, but the same result can be obtained by using a conductive or resistive roller, sponge, rubber, cloth-like member, etc. You can get some effect.

In addition to the brush used in this embodiment, the temporary developer stripping means may be one in which a voltage is applied to a conductive or resistive member with a moderately rough surface, such as a cloth-like member or a roller-like member. Good to have.

FIG. 8 shows another embodiment. In this embodiment, the temporary developer stripping means 2 and the transfer roller are connected to a power source 23, and a bias is obtained from the power source 23.

In this embodiment, since a DC bias having a polarity opposite to that of the toner is applied to the developer temporary peeling means 2 and the transfer roller 6, the power source for both is shared. However, it is conceivable that the appropriate values of the bias applied to the transfer roller 6 and the bias applied to the brush 2a are different. By controlling the resistance values of the transfer roller and brush, it is possible to obtain a good image with the same bias, but it becomes extremely difficult to select the materials for the roller and brush. Therefore, two different bias voltages can be applied to the transfer roller 6 and the brush 2a by creating a lower bias voltage by resistance-dividing the larger applied voltage. In Figure 9, transfer roller bias 800■,
The connection when a brush bias of 500V is applied is shown.

Further, although both the brush bias and the transfer roller bias may be kept ON at all times during the printing operation, it is desirable that the transfer roller bias be turned OFF between sheets in consideration of the dirt on the roller and the like. Also, regarding the brush bias, considering the accumulation of toner on the brush 2a, it is better to turn off the bias between sheets.

For these reasons, it becomes necessary to turn on and off the transfer bias and the brush bias at different timings. In this case, as shown in FIG. 10, the timing may be controlled by separate high voltage relays 101 and 102, respectively.

By using a common bias power source for the transfer means and the temporary developer stripping means, the apparatus can be made smaller and lower in price.

In this way, by applying an alternating current bias to the developer-disturbing member and non-bumping the untransferred image, it is possible to perform good printing without charging unevenness or memory images.

The conditions for performing the above-mentioned non-bumping are the nip di (+a11) formed by the image disturbing member and the image carrier, the moving speed V (+nm/5ec) of the image carrier, and the frequency Fr1 of the applied AC bias. (Ilz) needs to satisfy the following conditions.

Frl≦4000k (F rl Xd)/V≧
If the 2° frequency is too high, the toner will not be able to follow changes in the electric field, and if it is too low, sufficient toner transfer and reverse transfer will not take place between the image bearing member and the image disturbing member, resulting in residual toner remaining after transfer. De-blasting is not performed sufficiently, resulting in memory image and image unevenness.

In addition, by performing contact transfer, it is possible to perform good transfer with good transfer efficiency and no transfer waves even in a humid environment.Furthermore, by applying an AC bias, problems with the contact transfer method can be achieved. , it is also possible to prevent the occurrence of voids in the transfer of characters and line images. In order to obtain the above effects, the transfer nip d2 (m+s) formed by the image carrier and the transfer means, the moving speed of the image carrier V (mm/5e
c) and the frequency Fr2(I
lz) must satisfy the following conditions.

Fr2 ≦3500 and (Fr2 Xd2 )/V
≧20 The above-mentioned image disturbing means alone is useful for reducing memory images and image unevenness in a cleanerless process, and the above-mentioned transfer means improves transfer efficiency (especially in a humid environment) in a normal recording device. 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.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a compact recording device that can obtain clear images.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a recording apparatus according to an embodiment of the present invention, FIG. 2(a) is a graph showing characteristics of roller transfer, and FIG. 2(b) is a graph showing characteristics of charger transfer. A graph showing the characteristics, Figure 3 is a diagram showing the conditions of the brush potential and photoreceptor potential to increase the effect when AC + DC bias is applied, Figure 4 is a diagram showing the shape of the brush, and Figure 5 is a diagram showing the brush shape. , a graph showing the relationship between AC frequency and memory, Figure 6 is a diagram showing an example in which the static elimination lamp is placed before the brush, and Figure 7 is the graph after static elimination when pulse width modulation is performed in Figure 6. FIG. 8 is a diagram showing a recording device according to another embodiment, and FIGS. 9 and 10 are circuit diagrams near the power supply. 1... Photosensitive drum (image carrier) 2...
...Charging disruptor (developing cleaning means) 5...
...Transfer roller (transfer means) 10...
・Developing roller (elastic developing member) T・・・・・・・・・
Toner (developer) P・・・・・・Paper (transfer material)

Claims (3)

[Claims] (1) An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, and a developer charged to the same polarity as the electrostatic latent image formed by the electrostatic latent image forming means. a development cleaning device for removing developer remaining on the image carrier while performing reversal development; and a transfer device for transferring the developer image formed on the image carrier by the development and cleaning device to a transfer target member. , slidingly contacts the untransferred developer remaining on the image carrier after the transfer process by the transfer means and temporarily separates the untransferred developer from the image carrier by applying a bias; A recording apparatus comprising: a temporary developer stripping means for causing the developer to adhere to the image carrier again after a predetermined period of time has elapsed. (2) supplying an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier; and a developer charged to the same polarity as the electrostatic latent image formed by the electrostatic latent image forming means; a developer cleaning means for removing developer remaining on the image carrier while performing reversal development; a transfer means for transferring the developer image onto a transfer target member; a transfer means disposed so as to be in frictional contact with the image carrier, the transfer means being in sliding contact with the untransferred developer remaining on the image carrier after the transfer process by the transfer means; Temporarily separating the transfer residual developer from the image carrier by applying a bias;
A recording device comprising: a temporary developer stripping unit that causes the developer to adhere to the image carrier again after a predetermined time has elapsed; and a common power source that applies the bias to the transfer unit and the temporary developer peeling unit. . (3) an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier; and a developer charged to the same polarity as the electrostatic latent image formed by the electrostatic latent image forming means. a development cleaning means for removing developer remaining on the image carrier while performing reversal development; and a development cleaning means disposed in contact with the image carrier and to which a bias is applied;
a transfer means for transferring the developer image formed on the image carrier by the development and cleaning means onto a transfer target member; By slidingly contacting the remaining transfer residual developer and applying an AC bias, the transfer residual developer is temporarily separated from the image carrier, and after a predetermined period of time, the transfer residual developer is applied to the image carrier again. a developer temporary peeling means for adhering the developer; Fr1≦4000 and (Fr1×d1)/V≧20Fr
1 (Hz): Frequency of AC bias applied to the developer temporary peeling means d1 (mm): Nip width formed by the developer temporary peeling means and the image carrier V (mm/sec): The image carrier A recording device that satisfies the conditions of body movement speed.