JP3087500B2 - Electrophotographic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus utilizing electrophotographic technology.

[0002]

2. Description of the Related Art In an electrophotographic recording apparatus, after the well-known charging, exposing, developing and transferring steps, one of the methods for cleaning toner remaining on the surface of a photoreceptor without being transferred onto paper is conductive cleaning. A so-called bias cleaning method is known in which a charge of a polarity opposite to that of toner is applied to a member to rub the surface of the photoreceptor to remove the residual toner.
In the bias cleaning method, since the residual toner on the surface of the photoconductor is cleaned by an electrostatic force, the charged state of the residual toner greatly affects the cleaning performance. Generally, the polarity of the residual toner on the surface of the photoreceptor after the transfer is not uniform, and the reverse polarity or uncharged toner is mixed.

Therefore, according to Japanese Patent Application Laid-Open No. 63-15278, immediately before rubbing the photoreceptor with a conductive cleaning brush, the residual toner on the photoreceptor surface is uniformly charged by a DC charging means. There is known a method for enhancing the cleaning effect. According to Japanese Patent Publication No. 55-33075, in order to weaken the adhesion of the residual toner to the photoconductor and facilitate the separation of the residual toner from the photoconductor,
There is known a method in which a charge elimination charger and a light source lamp for simultaneously irradiating light beyond the discharge region of the charge elimination charger are provided to charge the photosensitive member.

[0004]

As described above, a charge supply means such as a DC charger is known to improve the cleaning property of the surface of the photoreceptor. However, when the residual toner is charged by the charge supply means. If the charge amount is excessive, the adhesive force between the residual toner and the photoreceptor becomes strong, and conversely, the cleaning property deteriorates. Further, the photosensitive member voltage after cleaning is not uniform, which hinders charging for the next image formation.

Further, the influence of the current flowing into the photoreceptor by the charge supply means (hereinafter referred to as the photoreceptor flow-in current) on the cleaning performance of the residual toner varies depending on the charged state of the residual toner. Residual toner can be roughly classified into the following four types according to the formation process. (1) The transfer of the toner image on the photoconductor was performed normally,
Part of the toner layer forming the toner image remains on the photoreceptor (hereinafter, usually referred to as residual toner). (2) Adhesion on the photoreceptor separately from the original toner image (Hereinafter, referred to as fogging residual toner) (3) On the photoreceptor, which cannot be brought into contact with the paper due to a jam (paper jam) or a paper part is missing, and is directly charged from the transfer unit. (4) Untransferred toner (jam residual toner) (4) Toner remaining on the photoreceptor due to insufficient power supply to the transfer unit (hereinafter referred to as non-power-supplied toner) Since residual toner having different characteristics exists on the body surface, it is necessary to maintain the value of the photoconductor inflow current within an appropriate range in order to clean all types of residual toner.

In the bias cleaning method, the width of rubbing between the conductive cleaning member and the photoreceptor affects the cleaning ability of residual toner on the photoreceptor surface and the life of the photoreceptor.
If the rubbing width is out of the proper range, the cleaning efficiency is reduced and the life is shortened due to the abrasion of the photoconductor.

Further, in the bias cleaning method, the resistance value of the conductive cleaning member has an influence on the cleaning performance. The resistance value of the conductive cleaning member is determined based on whether the conductive cleaning member is stationary with respect to the photosensitive member or the collection roller,
Alternatively, a different value is shown depending on whether it is in the operating state.
Here, what is particularly important for the cleaning property is the resistance value in the operating state, and the cleaning efficiency of the residual toner varies depending on the resistance value. However, the resistance value easily varies depending on the value of the voltage applied to the conductive cleaning member or the state of contact with the collection roller. Therefore, to keep the cleaning efficiency high,
It is important to know the resistance value measured under the same conditions as when cleaning the photoconductor. However, in an electrophotographic recording apparatus, the resistance value of the conductive cleaning member used for cleaning is usually measured when the conductive cleaning member is created or when the conductive cleaning member is not cleaned. Was not grasped.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the cleaning efficiency and extend the cleaning capacity maintenance time (life) in an electrophotographic recording apparatus using a bias cleaning method.
It is a further object of the present invention to make the current flowing into the photoconductor, the width of rubbing between the conductive cleaning member and the photoconductor during cleaning of the photoconductor, and the resistance value of the conductive cleaning member appropriate.

[0009]

The object of the present invention is to provide a transfer device for transferring a toner image formed on a photoreceptor to a transfer material, and a voltage for removing toner remaining on the photoreceptor after transfer. An electrophotographic recording apparatus having a bias cleaning device including a conductive cleaning member and a collection roller to which a higher voltage is applied than the conductive cleaning member for collecting toner adhered to the conductive cleaning member; A charge supply unit for applying a charge to the surface of the photoconductor and a light erasing unit for irradiating light to the surface of the photoconductor are arranged at a position between the charge cleaning unit and the upstream of the rotation direction of the photoconductor. This is achieved by performing light irradiation by the light erasing means outside the charge supply region.

Further, the absolute value of the DC component of the current flowing into the photosensitive member by the charge supply means is set to 0.01 to 0.2 μC /
cm ² . Further, the rubbing width between the conductive cleaning member and the photoconductor at the time of cleaning the photoconductor is 5 to 2 mm.
This is achieved by setting the distance to 0 mm. Further, it can be achieved by setting the value obtained by dividing the resistance between the conductive cleaning member and the collection roller at the time of cleaning the photosensitive member by the rubbing area of both members to be 0.003 to ² MΩ / cm ² .

[0011]

In the electrophotographic recording apparatus having the above configuration and conditions, the residual toner on the photoreceptor is cleaned through the following steps. (1) The toner image formed on the photoconductor is transferred to a sheet by a transfer unit. At this time, the toner that is prevented from being transferred to the paper remains on the surface of the photoconductor as residual toner.

(2) Prior to bias cleaning,
By supplying electric charge to the residual toner by the electric charge supply means, the polarity of the residual toner is made uniform, and the opposite polarity toner and uncharged toner are eliminated. (3) The light erasing means irradiates light outside the charge supply region by the charge supply means to weaken the adhesive force between the photoconductor and the residual toner. (4) The residual toner that has passed through the charge supply unit and the optical erase unit and has reached the conductive cleaning member has a voltage applied to the conductive cleaning member in addition to the mechanical action due to the rotational force of the conductive cleaning member. The surface of the photoreceptor is cleaned by the electrostatic attraction of the photosensitive member.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of an electrophotographic recording apparatus according to the present invention, in which a charger 2, an exposure unit 3, a developing device 4, Transfer device 5,
The charge supply unit 8, the optical erase unit 9, and the bias cleaning device 10 are arranged.

The operation of the electrophotographic recording apparatus will be described below. The photoreceptor 1 whose surface is uniformly charged by the charger 2 is exposed by the exposure unit 3 to form an electrostatic latent image. The electrostatic latent image is visualized by negatively charged toner when passing through the developing device 4 to form a toner image.
On the other hand, a positive charge is given from the transfer device 5 to the back surface of the paper 6 conveyed from a paper feeding device (not shown),
The upper toner image is transferred onto the paper 6. At this time, paper 6
Is not transferred to the surface of the photoreceptor 1 as residual toner. Most of the residual toner after the normal transfer is negatively charged. The residual toner is supplied with a current of preferably -0.02 to -0.1 [mu] C / cm < ² > by the charge supply means 8, and the electric charge is made negative. Next, after the light erasing means 9 irradiates light of ^{2 to} 10 μW / mm ² outside the charge supply area of the charge supply means 8, the power supply 14 supplies a bias voltage of +300 V to +1000 V having a polarity opposite to that of the residual toner. Is cleaned by the conductive cleaning member 11 to which is applied.

The toner adhered to the conductive cleaning member 11 is
The power supply 15 moves to the collection roller 12 to which a bias voltage of +500 to +1500 V, which is higher than the conductive cleaning member 11, is applied. Then, the collection roller 12
The upper toner is scraped off by the blade 13 and collected into the bias cleaning device 10. The collected toner is discharged from the inside of the bias cleaning device 10 by the screw 21, conveyed to the toner hopper 20, and used again for development.

In this embodiment, a brush is used as the conductive cleaning member 11. The brush used was a brush having a thickness of 4 to 6 denier and a length of 2 to 10 mm. The material used was carbon-mixed or carbon-containing acetate, or a resin such as polyamide. Outer diameter is 20 ~
40 mm and the length in the axial direction is 200 to 500 mm.
Note that a sponge-like member may be used as the conductive cleaning member 11 instead of a brush.

The material of the collection roller 12 is as follows.
The material is not limited to conductivity, and it is also possible to use SUS or an insulator such as an aluminum member whose surface is anodized.

In this embodiment, the power supplies 14 and 15 of the bias voltage applied to the conductive cleaning member 11 and the collection roller 12 are provided.
Are provided separately, but the conductive cleaning member 1
If a configuration is adopted in which a bias voltage higher than 1 is applied, a common applied voltage power supply 22 can be used as shown in FIG.

In this embodiment, the polarity of the charge applied by the charge supply means 8 is the same as that of the residual toner, but the opposite polarity is used, and the conductive cleaning member 11 and the collection roller 1 are used.
The same cleaning effect can be obtained by applying a bias voltage having the opposite polarity to the above to 2. However, when the recovered toner is used again for development, it is preferable that the applied polarity of the charge supply means 8 be the same as that of the residual toner. This is because the charging time of the toner in the developing device 4 can be reduced by charging the toner in advance. In the present embodiment, DC is used as the charge supply means 8. However, the present invention is not limited to this. The AC component is superimposed on the DC component, and the DC component satisfies the above conditions. You may.

FIG. 2 is a sectional view showing an embodiment of the charge supply means 8 and the optical erase means 9. FIG. 2A shows a configuration in which the charge supply means 8 and the optical erase means 9 are provided side by side and assembled in the same mold. In the figure, 16 is a shield plate,
Reference numeral 17 denotes a tube light source lamp, and reference numeral 18 denotes a shielding plate. FIG. 2B shows a configuration in which the optical erase unit 9 is provided on the back surface of the charge supply unit 8 and the light reflected by the light-shielding plate 18 having the inner wall as a reflecting surface is applied to the photoconductor 1. Fig. 2 (c)
The light erasing means 9 is provided at a position which is not limited to the periphery of the photoreceptor 1, and the light from the tube lamp light source lamp 17 is guided by the optical fiber 19 or the like to irradiate the photoreceptor 1 after passing through the charge supply means 8. is there.

FIG. 2D shows an optical erasing means 9 provided on the back surface of the charge supply means 8 as in FIG. 2B so that light irradiation by the optical erase means 9 is performed before and after the charge supply means 8. is there. Further, as an application of this example, two light sources are arranged before and after the charge supply means 8 and these are integrated or formed by separate molds, and light is directly irradiated onto the photoreceptor from the light source as shown in FIG. It is also possible to do. FIG. 2E shows an example in which the light-emitting diode 17b is used as the optical erase means 9. In addition, FIG.
2D, a light source other than the tube light source lamp 17 such as the light emitting diode 17b can be used as in FIG. Also, in FIGS. 1 and 2, a corotron type charger is shown as the charge supply means 8, but a scorotron type charger is more preferable.

As described above, by integrating the charge supply means 8 and the optical erase means 9 into an integrated unit, the size of the apparatus can be reduced and maintenance can be facilitated. Further, if the charge supply means 8, the optical erase means 9 and the bias cleaning device 10 are integrated as shown in FIG. 7, further downsizing can be achieved.

FIG. 3 is a sectional view showing another embodiment of the bias cleaning device 10. A collection roller 12 is provided at a position upstream of the conductive cleaning member 11 in the rotation direction of the photoconductor 1 in contact with or close to the photoconductor 1. According to this configuration, there is an advantage that the collection roller 12 assists the cleaning of the photoconductor 1, and further, the toner that has fallen downward due to the rotation of the conductive cleaning member 11 can be collected.

FIG. 4 is a characteristic diagram showing the amount of charge supplied to the photosensitive member 1 by the charge supply means 8 and the residual toner cleaning property. In the figure, a represents the cleaning characteristic of the normal residual toner, b represents the fogging residual toner, c represents the cleaning characteristic of the jam residual toner, and d represents the cleaning characteristic of the non-power supply residual toner. The cleaning efficiency was determined by y / x, where x is the residual toner amount on the photoconductor after transfer, and y is the value obtained by subtracting the residual toner amount after passing through the bias cleaning device from x. The area where the cleaning efficiency is 80% or more is indicated by A. As can be seen from FIG. 4, a, b, c, and d each have a different charge supply amount contained in A.
In order for all of d to be included in A, it is necessary to supply electric charges having an absolute value of the DC component of 0.02 to 0.1 μC / cm ² . If only a and b are to be cleaned, the absolute value of the DC component is not shown,
What is necessary is just 0.2 μC / cm ² . In a system that can be set with a lower cleaning efficiency, the absolute value of the DC component is not shown, but can be set to 0.01 to 0.2 μC / cm ² .

FIG. 5 shows the rubbing width between the conductive cleaning member and the photosensitive member.
FIG. 4 is a characteristic diagram of a residual toner cleaning property and a photoreceptor life. a,
The symbols b, c, d and A mean the same as in FIG. e indicates the ratio of each photoconductor life LB to the photoconductor life specification value LA when the rubbing width is changed,
B indicates an area where LB / LA is 1 or more.
This means an appropriate area in view of the life of the photoconductor. FIG.
As can be seen from the graph, as the rubbing width increases, the cleaning efficiency increases, but the photoreceptor wears due to the rubbing of the conductive cleaning member and the life of the photoreceptor decreases. Therefore, the appropriate value of the rubbing width is in the range of 5 to 20 mm included in both A and B.

FIG. 6 is a characteristic diagram of the resistance value of the conductive cleaning member and the cleaning property of the residual toner. The meanings of the symbols a, b, c, d and A are the same as in FIGS. As can be seen from FIG. 6, the cleaning efficiency varies depending on the resistance value. Here, assuming that the area indicated by A is an appropriate range, the value obtained by dividing the resistance between the collection roll and the conductive cleaning member by the rubbing area between the two is preferably in the range of 0.003 to ² MΩ / cm ² . It is preferable that the decrease in cleaning efficiency is small, that is, 0.01 to 1 MΩ / c.
m ² , more preferably 0.03 to 0.8 MΩ / cm ² , where the cleaning efficiency is hardly reduced.

The conditions in the experiments shown in FIGS. 4 to 6 are as follows. Photoreceptor peripheral speed: 250 mm / s Toner charge: 15 to 25 μC / g Conductive cleaning member: A fiber made by dispersing carbon in a resin such as acetate or polyamide (brush) or a carbon layer contained in the resin Fiber Conductive cleaning member: 135 rpm Number of rotations: Photoconductor peripheral speed: 100 mm / s, 400 mm /
s, toner charge amount: 10 to 20 μC / g, 20 to 30 μ
Similar results were obtained when C / g and the number of rotations of the conductive cleaning member were 50 to 200 rpm.

[0028]

According to the present invention, in an electrophotographic recording apparatus using a bias cleaning method, a charge supply means and an optical erase means are arranged between a transfer device and a bias cleaning apparatus, and light is supplied outside the charge supply area. Since the irradiation is performed, the residual toner on the surface of the photoconductor can be efficiently cleaned, and the contamination of the transfer material in the next cycle due to poor cleaning can be suppressed.

Further, the appropriate values were obtained by dividing the current flowing into the photosensitive member, the width of the rubbing between the conductive cleaning member and the photosensitive member, and the resistance between the conductive cleaning member and the collecting roller by the rubbing area of both. It is possible to always maintain a stable cleaning property without shortening the life of the body. Further, in a system in which the collected toner is reused for development, the charging time of the toner in the developing machine can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing an embodiment of a charge supply unit and an optical erase unit according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the bias cleaning device according to the present invention.

FIG. 4 is a characteristic diagram of a charge supply amount and a residual toner cleaning property.

FIG. 5 is a characteristic diagram of a conductive cleaning member rubbing width, a residual toner cleaning property, and a photoreceptor life.

FIG. 6 is a characteristic diagram of a resistance value of a conductive cleaning member and a cleaning property of residual toner.

FIG. 7 is a sectional view showing another embodiment of the charge supply unit, the optical erase unit, and the bias cleaning device according to the present invention.

[Explanation of symbols]

1 is a photoreceptor, 5 is a transfer unit, 8 is a charge supply unit, 9 is an optical erase unit, 10 is a bias cleaning device, 11 is a conductive cleaning member, 12 is a collection roller, 13 is a blade,
Reference numeral 14 denotes a voltage power supply applied to the conductive cleaning member, and 15 denotes a voltage power supply applied to the collection roller.

Continuation of the front page (56) References JP-A-63-249180 (JP, A) JP-A-62-270987 (JP, A) JP-A-63-76862 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 21/06-21/08

Claims (5)

(57) [Claims] A transfer device for transferring a toner image formed on a photosensitive member to a transfer material; a conductive cleaning member to which a voltage for removing toner remaining on the photosensitive member after transfer is applied; An electrophotographic recording apparatus having a bias cleaning device including a collection roller to which a higher voltage is applied than the conductive cleaning member that collects toner adhered to a cleaning member, wherein a bias cleaning device is provided between the transfer device and the bias cleaning device. A charge supply means for applying a charge to the surface of the photoreceptor and a light erasing means for irradiating light to the surface of the photoreceptor are arranged in the order from the upstream in the rotation direction of the photoreceptor, and the light erasing means is provided outside the charge supply area by the charge supply means performs a light irradiation by the absolute value of the DC component of the current flowing into the photosensitive member by the charge supply means is defined by the appended 0.01~0.2μC / cm ² Rubbing width between the conductive cleaning member and the photosensitive member at the time of the photosensitive body cleaner is defined in the appended 5 to 20 mm,
The value obtained by dividing the resistance between the conductive cleaning member and the collection roller at the time of cleaning the photoconductor by the rubbing area between the two is 0.003.
An electrophotographic recording apparatus defined in the range of ^{2 to 2} MΩ / cm ² . 2. An electrophotographic recording apparatus according to claim 1, further comprising an optical erasing means disposed at a position upstream of the charge supply means in the photoconductor rotation direction. 3. An electrophotographic recording apparatus according to claim 1, wherein said charge supply means and said optical erase means are provided in the same unit. Wherein said bias cleaning apparatus, electrophotographic recording apparatus according to claim 1, wherein the said charge supplying means and the light erasing means is provided in the same unit. Wherein said connecting conveying means to bias the cleaning apparatus, electrophotographic recording apparatus according to claim 1, characterized by using again developing the recovered toner by the collecting roller.