JPH04204787A - Electrostatic image forming device - Google Patents

Abstract

PURPOSE:To efficiently recover residual toner with a simple mechanism and to reuse it by providing a brush slidably rotated with the surface of a photosensitive drum on the middle part of a transfer device and an optical image projecting part. CONSTITUTION:The brush 15 slidably rotated with the surface of the photosensitive drum 1 on the middle part of the projecting part projecting the optical image 4 on the photosensitive drum 1, and the transfer device 10 transferring a toner image on the drum 1 on a recording medium 9, is provided, and the residual toner 17 on the photosensitive drum is tentatively attracted and removed. Then, the toner 17 is dispersed on the photosensitive drum to be reattracted, and recovered by a developing machine 5. The voltage of a polarity for attracting the toner 17 remaining on the surface of the photosensitive drum and the voltage of the reverse polarity are alternately applied on the brush 15. Thus, the toner remaining on the photosensitive drum can be recovered and reused.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to copying machines, printers, etc., and in particular to electrostatic machines that produce visible images by attaching colored toner to an electrostatic latent image formed on the surface of a photosensitive drum. The present invention relates to an image forming apparatus.

[Prior art] The above-mentioned conventional copying machine and printer were manufactured by the Special Publication No. 58-1110.
As described in Japanese Patent Application No. 78, an electrostatic latent image was formed on the surface of a photoconductive photosensitive drum, a developer containing colored toner was attached to the electrostatic latent image, and the image was transferred onto recording paper.

[Problem to be solved by the invention] In the above-mentioned conventional copying machines and printers, it is necessary to clean, collect and dispose of the toner remaining on the photosensitive drum, and a win-win mechanism is required for this purpose. However, there was a problem in that maintenance and inspection were cumbersome.

Furthermore, the amount of toner discarded due to the above-mentioned cleaning can reach as much as 20% of the total amount of toner consumed, which poses the problem of being uneconomical.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic image forming apparatus that can efficiently collect the residual toner and reuse it using a relatively simple mechanism.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an intermediate part between an irradiation unit that irradiates a photosensitive drum with a light image and a transfer device that transfers a toner image on the photosensitive drum to a recording medium. A brush that slides and rotates on the surface of the photosensitive drum is provided to once remove residual toner on the photosensitive drum by suction, then disperse it onto the photosensitive drum and suck it again, and collect this toner with a developing machine.

For this reason, a voltage of a polarity that attracts the toner remaining on the surface of the photosensitive drum and a voltage of the opposite polarity are alternately applied to the brush.

Further, a voltage of a polarity that attracts toner remaining on the surface of the photosensitive drum of the power supply is applied to a non-printing part of the recording medium or a period when the recording medium is absent, and a voltage of the opposite polarity is applied to the recording medium. By applying the voltage to the printing section, the brush also charges the surface of the photosensitive drum.

Roughly, a wrap roll (in sliding contact with the brush) and a cut filter in sliding contact with the above-mentioned wrap roll are provided to remove coarse particles of paper powder, dust, and toner collected by the brush. -, etc. are removed by the trap roll, and these harmful substances are further collected by the cut filter.

[Function 1 Electrostatic image forming vcW of the present invention configured as shown below-1]
In this method, the residual toner on the photosensitive drum is once removed by suction using the brush, then dispersed onto the photosensitive drum and sucked again, and then this toner is collected by a dyeing machine.

Further, the residual 1.sup.- is removed by suction in a non-printing section of the recording medium or a period in which the recording medium is absent, and then the toner "-" is again applied to the surface of the photosensitive drum in the printing section of the recording medium. 1f, which also charges the photosensitive drum.

Furthermore, the brush, trap roll, and cut filter remove and collect filter paper powder, dust, coarse particles of toner, etc. that are adhered to and transported on the photosensitive drum.

[Embodiment] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus according to the present invention.

In FIG. 1, the surface of a photoconductive drum 1 is uniformly charged by a corona charger 2 as it rotates. 3
is the power source of the corona charger 2. If a negatively charged organic photoreceptor is used, the photosensitive drum 1 will be negatively charged at the point shown in the figure.

Next, a photoimage 4 is irradiated to form a charge latent image on the surface of the photosensitive drum 1, and a developing device 5 reversely develops the -1- charge WI image. A developing roll 6 that attracts a developer made of toner and magnetic carrier is housed in the developing device 5, and its rotation attracts and sets the toner on the latent charge image on the surface of the photosensitive drum 1. Reference numeral 7 denotes a developing bias power source for the developing roll 6, in which an alternating current is superimposed on a direct current having the same polarity as the negative voltage on the surface of the photosensitive drum 1, and the adsorbed carbon of the toner is adjusted by the voltage.

Next, the photosensitive drum 1 comes into contact with the paper 9, and the positively charged transfer roll 10 transfers the photosensitive drum 1! ! The negative potential toner images on the two sides are attracted and transferred to the paper 6 side.

11 is a power source for the transfer roll 10; Note that a corona charger may be used instead of the transfer roll 10.

Photosensitive drum l after the above conversion! I! Since 5 to 20% of the initially sucked toner remains on the surface, it is necessary to remove it or scatter it uniformly so that it does not interfere with the next image forming process.

For this reason, in the present invention, the toner remaining on the surface of the photosensitive drum 1 is recharged to the same polarity by the recharging device 12, and then the residual toner is sucked and removed by the endless brush 15, or is uniformly scattered. do. 13 is a power source for the recharger 12, and 14 is an erasing lamp for adjusting the recharging potential of the residual toner that has been distributed and charged.

Further, reference numeral 16 denotes a power supply having a polarity opposite to that of the residual toner applied to the brush 5, which sucks and peels the residual toner from the surface of the photosensitive drum.

If the residual toner is continued to be removed by suction as described above, toner will accumulate on the brush 15, so there will be a period during which the device does not record an image, such as a period during which a page is cut or a blank sheet after printing is not recorded. During this process, the toner accumulated on the brush 15 is again sucked onto the photosensitive drum 1 and discharged, and collected in the current fa device 5 in the next step.

For this purpose, each power source is controlled as shown in FIG.

In FIG. 2, tl is the recording period during which the reversal development is performed, and L is the same non-recording period.7For example, the surface potential of the photosensitive drum 1 is -600V, and the developing bias voltage V is -400V during period t3. be. Also, L.

During this period, the developing bias voltage (1) is reversed to +250V, and the toner discharged onto the photosensitive drum 1 from the brush 15 is sucked into the developing roll 6 and collected into the developing machine 5.

In addition, ■ is the voltage of the transfer power source 11. The toner image on the photosensitive drum 1 developed by the developing device 5 reaches the transfer roll 10 after the start of development.
During the period, the toner image on the photosensitive drum 1 is transferred to the paper 9 by setting the voltage to +100V. Also, t.

For the period (4), for example, -600 (2) is set to prevent the toner on the photosensitive drum 1 from adhering to the transfer roll 10, or to return the toner adhering to the transfer roll 10 to the photosensitive drum 1.

(2) is the voltage of the cleaner power supply 16. The toner image on the photosensitive drum 1 developed by the developing device 5 is L from the start of development.
Since the brush 15 is reached after 4, the next 1 period,
(2) is set to +250■ to collect the residual toner on the photosensitive drum 1, and for the next period, (3) is switched to -300■ to return the toner to the photosensitive drum 1 side.

Furthermore, if the direction of rotation of the brush 15 is reversed when collecting the residual toner, toner that has entered the deep part of the brush and toner with attenuated charge can be removed from the photosensitive drum.
can be easily spit out.

If the amount of the residual toner is relatively small, it is sufficient to scatter it onto the surface of the photosensitive drum 1 without capturing it with the brush 15F, so for 1 period ■, +100
It is possible to superimpose an AC voltage of about ~-1oOV, or as ■, 0.5 to 10kHz, 100 to 100OV.
It is also possible to use a superimposed alternating current voltage of approximately

Not shown in FIG. 2, polarity reversals such as J, sea urchin, V, , ■8, ■3, etc. are reversed at each development printing process.

The brush 15 is made of a material containing carbon, magnetite particles, etc. with a volume resistance of 101 to io''Ωc ni and a thickness of 10.
~30 μm fibers made of nylon, acrylic, acedate, etc., flocked at a density of 10,000 to 20,000/e m', length 3 to 10
Preferably, it is formed into a brush shape of mm.

FIG. 3 is a diagram showing another embodiment of the present invention in which the recharger 2 is omitted from FIG. 1.

Regular development is used in the apparatus shown in FIG.

In FIG. 3, the photosensitive drum 1 is charged substantially in a negative manner by a brush 15 connected in series with a cleaner power source consisting of a DC power source 16 and an AC source 19.

If the photoconductor of the photoconductor drum 1 is a negatively charged organic photoconductor, the voltage of the DC power supply 16 is set to, for example, -400 to -700V.
, the voltage of the AC power supply 19 is 3oo to 5o.

When V r m s, the photoreceptor charging potential is approximately -4
°O~-700V.

As the brush 15, the one mentioned above can be used,
It is preferable to use fibers having a volume resistivity of 10' to 10' Ωcm.

Next, a light image 4 is irradiated to form a charge latent image, and a developing device 5 applies positively charged toner to develop the negative charge latent image.

Next, the toner image on the photosensitive drum is transferred onto the paper 9 by the transfer roll 10, and the toner remaining on the photosensitive drum is collected by the brush 15 and uniformly scattered.

The toner collected by the brush 15 is returned onto the photosensitive drum in the same manner as in FIG. 1, and collected by the developing device 5.

FIG. 5 shows voltage waveforms of each power source when reversal development is applied to the apparatus of the present invention shown in FIG.

Here, both the photosensitive drum 1 and the toner are negatively charged.

In Fig. 5, the DC power supply ■ of the cleaner is, for example, −5
When the voltage is fixed at 00V, the surface of the rotating photosensitive drum 1 is uniformly negatively charged. 1. After a time t from the start of charging, the optical image is exposed for a period t1 by the control signal S. Since the exposed portion arrives at the developing machine 5 after a period of time from the start of the exposure, the bias voltage V of the developing roll 6 is maintained during the subsequent 8 period.
1 is developed at -350V, for example, and the remaining toner on the photosensitive drum 1 is collected at +350V for the following three periods into the developing device 5.

Further, since the toner image developed on the photosensitive drum 1 reaches the transfer port 1o after t from the start of the development, the voltage V of the transfer power source 11 is maintained during the subsequent period t1.

For example, the toner image on the photosensitive drum l is transferred to the paper 9 by setting the voltage to +100OV, and for the next three periods, set the voltage to -10OV, for example.
00■, the toner on the photosensitive drum 1 is transferred to the transfer roll 10.
or to return the toner attached to the transfer roll 10 to the photosensitive drum 1.

Thereafter, the toner remaining on the photosensitive drum 1 is removed by the brush 15.
Since it is a negative potential, the photosensitive drum 1 is not attracted to it.
It is scattered on top and collected into the developing machine 5 during the next process.

FIG. 6 is a diagram showing another structure around the brush 15 according to the present invention.

In FIG. 6, a trap roll 21 and a cut filter 22 are added to the periphery of the brush 15 to enhance the effect of collecting residual toner on the photosensitive drum 1.

The trap roll 21 rotates in contact with the brush 15, and between the trap roll 21 and the brush 15, a bias power supply 24 that is a direct current or a superimposed direct current and an alternating current is connected.

The trap roll 21 collects coarse particles, paper dust, and dust particles in the toner sucked or scraped from the photosensitive drum 1 by the brush 15, and the cut filter 22 functions to remove these unnecessary harmful substances from the trap roll 21.

As a result, paper dust, dust, coarse particles in toner, insufficiently charged toner, etc. generated during the image forming process can be removed, preventing local dirt and clogging of the brush 15 and reusing it. Only available toner can be collected.

Further, the toner captured by the brush 15 is transferred to the trap roll 2.
Since the particles are dispersed upon contact with the photosensitive drum 1, they can be returned to the photosensitive drum 1 after being dispersed widely and uniformly.

Bias voltage '#, 23 is the 1st I3! Since it performs the same function as the cleaner power source 16 shown in FIG. 1 and FIG.

In addition, the bias power source 23 of the brush 15 and the bias power source 24 between the trap roll 21 and the brush 15 are
An even better effect can be obtained by changing it in the same way as v3 in the figure.

In addition, if the surface of the trap roll 21 is made of alumite-treated aluminum to increase the resistance, or if a resin insulating layer with a thickness of 5 to 20 μm is provided on the surface, the electric resistance value of the brush 15 is often low. The generated electric field concentration at the tips of the brush fibers can be alleviated, and thus the bias power supply 24 can be omitted. In this case, when the trap roll 21 is grounded, its surface portion is charged to a slightly lower potential than the bias power supply 23.

Each of the above-mentioned embodiments of the present invention can be applied not only to the case of forming a charge latent image by the above-mentioned electrophotographic method, but also to the case of forming a charge latent image by an electrostatic recording method, an ion control charging method, etc. effect can be obtained.

[Effects of the Invention] According to the present invention, toner remaining on the photosensitive drum can be collected and reused.

Furthermore, since the photosensitive drum can be charged by the brush that collects the residual toner, the corona charger or other type of photosensitive drum charging device of the conventional device can be omitted.

Furthermore, the brush device of the present invention shown in FIG.
Alternatively, since insufficiently charged toner and the like can be removed from the photosensitive drum, local staining and clogging of the brush can be prevented, and only reusable toner can be collected.

Due to the above-mentioned effects, the amount of toner used can be reduced, and
It is possible to simplify the mechanism of the electrostatic image forming apparatus, improve its reliability, maintainability, etc., and at the same time improve the quality of the image.

[Brief explanation of the drawing]

1 and 3 are block diagrams of an electrostatic image forming apparatus according to the present invention, FIGS. 2, 4, and 5 are voltage waveform diagrams explaining the present invention in detail, and FIG. 6 is a diagram of a toner cleaner according to the present invention. It is a figure which shows the other structure of a brush part. 1... Photosensitive drum, 2... Corona charging, banquet, 3...
・tW, 4... Optical image, 5... Developing machine, 6... Developing roll, 7... Developing bias power supply, 8... Toner image, 9... Paper, 10... Transfer roll, 11...
Power source, 12... Recharging device, 13... Recharging power source, 1
4... Erasing lamp, 15... Brush, 16... Cleaner power supply, 17.20... Each collected toner, 18...
・Toner image, 19...AC cleaner power supply, 21...
Trap roll, 22...Cut filter, 23...
- Brush bias power supply, 24... Trap roll bias power supply. Name of Patent Applicant Hitachi Koki Co., Ltd. (No change in content) 1 Figure 3\ ) 2 Figure 3) 5 Figure March 22, 1991

Claims (1)

[Claims] 1. A light image is irradiated onto the surface of a charged photosensitive drum to form a charge image, toner is attached to the charge image and developed, and the toner image is transferred to a recording medium by a transfer device. An electrostatic image forming apparatus characterized in that a brush that slides and rotates on the surface of the photosensitive drum is provided at an intermediate portion between the transfer device and the light image irradiation section. 2. In claim 3, the brush is provided with a power source that alternately generates a voltage of a polarity that attracts toner remaining on the surface of the photosensitive drum and a voltage of the opposite polarity to the brush, and the power source is connected to the brush. An electrostatic image forming apparatus characterized by: 3. In claim 2, a voltage of a polarity that attracts toner remaining on the surface of the photosensitive drum of the power source is applied to a non-printing part of the recording medium or a period when the recording medium is absent,
An electrostatic image forming apparatus characterized in that the voltage having the opposite polarity is applied to the printing portion of the recording medium. 4. An electrostatic image forming apparatus according to claim 1, further comprising a trap roll that comes into sliding contact with the brush, and a cut filter that comes into sliding contact with the trap roll.