JPH05307311A - Electrophotographic copying device - Google Patents

Abstract

PURPOSE:To prevent the unevenness of electrification and to reduce the wear and tear of a brush tip and an image carrier by providing a means which vibrates an electrifying member under a state that it is brought into contact with the image carrier. CONSTITUTION:A vibration means 8 is provided on one end of an electrifier 3 consisting of the electrifying brush 5 constituted of electrical conductive fiber 4 which is brought into contact with the image carrier 2 on the surface of a photosensitive drum 1. Besides, a repulsive means 11 such as a spring is provided on the other end of the charger 3. The vibration means 8 is constituted so as to be vibrated by inputting a pulse output from a pulse oscillation circuit 9 to a control circuit 10 and inputting an On/OFF control signal outputted from the control circuit 10 to an ON/OFF switch provided in the vibration means 8. Then, since the brush 5 constituted of the fiber 4 is vibrated under the state that it is brought into contact with the carrier 2 when the brush 5 is electrostatically changed by being brought into contact with the carrier 2, the brush 5 and the carrier 2 are not continuously brought into contact with each other at an identical contact point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine, and more particularly to improvement of a brush-shaped charging member made of conductive fibers used in an electrophotographic copying machine.

[0002]

2. Description of the Related Art As is well known, many proposals have already been made for copying machines, and in recent years, electrophotographic copying machines have become the mainstream. The basic configuration of such an apparatus is as follows: photoconductor drum / charging device / exposure device / developing device / transfer device /
A static eliminator / cleaner is arranged around the photoconductor drum to perform a series of electrophotographic processes, and as a path for copy paper, a paper tray / paper guide / paper feed roller / transfer device / suction unit (conveyance) / Fixing device / paper discharge roller is a basic structure, and the image transferred on the paper is fixed to obtain a copy. Among these, as a charger for charging the photoconductor to a desired potential, a corona charger using corona discharge has been conventionally used.
In this method, a high voltage is required, and therefore, there is a fear that the microcomputer or the like is electrically affected. In addition, a large amount of ozone is generated at the time of corona discharge, which not only deteriorates the photosensitive member and the resin member such as the cleaning blade in the machine, but also gives an unpleasant feeling, which is an environmental problem. In order to solve such a problem, a means for applying a voltage to a conductive roller or a fiber assembly to charge the photoconductor has been proposed.

For example, in Japanese Laid-Open Patent Publication No. 2-62563, in order to construct the above-mentioned charger, the conductive direction is used as a charging member and the rotating direction of the image carrier (photoconductor) forming the surface of the photoconductor drum. It is disclosed to use a charging brush in which the fibers are flocked so as to form a loop in a direction substantially perpendicular to. FIG. 7 is an explanatory view showing the structure,
In the figure, 1 is a photoconductor drum, 2 is an image carrier (photoconductor), and 3 is a charger, which is a conductive fiber 4
The charging brush 5 is formed by forming a loop shape as shown in the figure.
However, the loop-shaped conductive fibers 4 are planted on the conductive substrate 7 with the conductive adhesive 6 to form the charging brush 5. In this case, the photosensitive drum 1 rotates and moves in the direction of the arrow R, while the loop of the conductive fiber 4 is planted in a direction substantially perpendicular to the moving direction. According to this means, streak-shaped charging unevenness can be prevented as compared with the conventional charging brush by using this means.

[0004]

However, in the first place, the main cause of the above-mentioned streak-shaped charging unevenness is that the brush-shaped charging member made of conductive fibers is applied to the same contact point of the image carrier. There are things that are caused by contact for a long time,
Further, since the same point on the image carrier is rubbed by such a long-time contact, the image carrier is easily scratched, and at the same time, the brush side is quickly worn.
In addition, the developer gradually accumulates on the tip of the brush, causing contamination, which is also a problem. Regarding these points, even if the above-mentioned known technique is adopted, they are still unsolved, and a fundamental solution is desired. Therefore, an object of the present invention is to prevent uneven charging occurring in the paper feeding direction when using a brush-like charging member composed of conductive fibers for a charger and reduce wear of the brush tip and the image carrier. Another object of the present invention is to provide an electrophotographic copying apparatus which solves the problem of developer accumulation on the tip of the brush which causes contamination.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and one of the gist of the invention is to provide a brush-shaped charging member composed of conductive fibers as an image. An electrophotographic copying apparatus is provided with means for vibrating the charging member in contact with the image carrier when the image carrier is charged by bringing it into contact with the carrier. Another aspect of the present invention is to bring a brush-shaped charging member made of a conductive fiber into contact with the image carrier, and to contact the image carrier with the charging member when charging the image carrier. In the electrophotographic copying apparatus, means for vibrating in a state is provided, and a comb-shaped vibration regulating member is penetratingly held over the entire surface of the conductive fiber portion.

[0006]

In the present invention, when the brush-shaped charging member made of conductive fiber is brought into contact with the image carrier to charge it, the charging member vibrates while the contact state shown on the left is maintained, so that The image carrier does not continue to contact at the same contact point, which can prevent charging unevenness and reduce wear of the brush tip and the image carrier. Further, in the present invention, since the vibration regulating member is held through the entire surface of the conductive fiber portion, the developer that is trying to be deposited on the brush tip by vibrating the charging member is wiped off by the regulating effect of the regulating member. Therefore, the developer is not accumulated and the contamination can be avoided.

[0007]

EXAMPLES The present invention will be described below based on examples. First, known conductive fibers can be used as the conductive fibers constituting the brush-shaped charging member in the present invention. For example, rayon fiber is used as the fiber, and carbon particles are uniformly dispersed in the fiber to obtain a desired resistance value. ) "Bertron" equivalent product, etc. can be used by appropriately selecting any material. These conductive fibers are used to form a pad, and a conductive adhesive is used to adhere to the conductive substrate to form a charging brush, which is then brought into contact with the photosensitive drum as a charger.

FIG. 1 is a perspective view showing the positional relationship between the charger and the photosensitive drum in the present invention. In the figure, 1 is a photosensitive drum, and 2 is an image bearing member (photosensitive member). on the other hand,
Reference numeral 3 denotes a charger, in which conductive fibers 4 as a charging member are planted on a conductive substrate 7 with a conductive adhesive 6, whereby a charging brush 5 is formed to constitute the charger 3. In this case, the photosensitive drum 1 is rotated in the direction of arrow R, while the charging brush 5 in contact with the image carrier 2 on the surface of the photosensitive drum 1 is in the direction of V (in FIG.
A vibrating means to be described below is provided so as to vibrate in a direction (perpendicular to the direction).

An example of means for vibrating the charger 3 will be described with reference to the drawings. FIG. 2 is a conceptual explanatory view showing one embodiment of the constitution of means for giving vibration to the charger 3 in the present invention. In FIG. 2, a vibrating means 8 is provided at one end of a charging device 3 composed of a charging brush 5 made of a conductive fiber 4 that comes into contact with the image carrier 2 on the surface of the photosensitive drum 1, and at the other end thereof. Repulsion means 11 such as a spring is provided. The vibrating means 8 outputs the pulse output from the pulse oscillation circuit 9 to the control circuit 10
Is input to an ON / OFF switch provided in the vibrating means 8 so that the vibrating means 8 is vibrated. In this case, as the vibrating means 8,
A known device, such as a solenoid or a ceramic oscillator, can be appropriately used, and a device capable of performing stable vibration in a short cycle is particularly preferable.

Next, the operation of the vibrating means of FIG. 2 will be described with reference to the diagram showing the timing of a series of operations of the control circuit 10 shown in FIG. First, in oscillating the charger 3, the pulse oscillated by the pulse oscillating circuit 9 is counted by a counter. As shown in FIG. 3, for example, as shown in FIG. Each time 10 counters are input, the counter output shown in (B) is output 1 time, the output pulse is input to the control circuit 10, the rising edge of the pulse is detected, and each time this edge is detected. As shown in FIG. 3C, an ON / OFF control signal is sent to a switch built in the vibrating means 8, and the vibrating means vibrates by the signal, and in synchronization with this, the charger 3 moves in the direction of arrow V. Will give vibration to. As a result, the conductive fiber 4 which is the charging member of the charging brush 5 which constitutes the charger 3 moves in a direction substantially perpendicular to the moving direction R of the image carrier 2 provided on the surface of the photosensitive drum 1 in the same figure. Therefore, the charging member (the fibers 4) and the image carrier 2 do not continue to come into contact with each other at the same contact point.

Further, when the vibrating means 8 is turned off and returns to the original position, it is effective that a repulsion means 11 such as a spring is provided at the other end of the charger 3 as a mechanism for a returning operation in order to assist this. Therefore, the vibration motion is V
It is possible to more reliably perform the reciprocal movement in the direction. In this case, it is most effective to prevent the streaky charging unevenness from occurring by making the V direction of the reciprocating motion substantially perpendicular to the rotational movement direction R of the photosensitive drum. Furthermore, the vibration cycle of the vibrating means 8 should be as short as possible so that the charging member can follow it, and if it becomes too slow, the conductive fiber 4
When the charging member constituted by is vibrated at a right angle to the rotational movement direction R of the image carrier 2, uneven charging may occur in the paper feeding direction. By vibrating in a short vibration cycle, it is possible to prevent uneven charging caused by the tip of the conductive fiber 4 being in contact with the surface of the image carrier 2 for a long time. Contamination due to the developer can also be removed by vibration. In this case, the desirable vibration cycle is 1 Hz or more, and the upper limit is not particularly set, but practically about 60 Hz is optimal, and the practical vibration cycle seems to be up to about 300 Hz. Under the above conditions, the charger 3
By applying a DC voltage 1.5 times or more higher than that of the image carrier 2, it is possible to suppress the charging unevenness, which has been a problem in the past.

Next, another gist of the present invention will be described with reference to the drawings. First, FIG. 4 is a conceptual explanatory view showing an embodiment of the configuration in the case where the vibration regulating member is used in the present invention. The configuration of FIG. 4 is basically the same as that of FIG. 2, but in FIG. 4, the comb-shaped vibration regulating member 12 penetrates the entire surface of the portion of the conductive fiber 4 that is the charging member that constitutes the charger 3. It is held. The vibration regulating member 12 has a comb shape as shown in the plan view of FIG. 5, and the conductive fiber 4 has a comb shape as shown in the plan view of FIG.
Actually, the "comb teeth" of the restriction portion 12 penetrate between the fibers 4 and are penetrated and held in such a manner that the spaces between the teeth of the comb are filled. In these drawings, particularly in FIG. 4, the vibrating means 8 and its control system and the repulsion means 11 shown in FIG. 2 are omitted to simplify the drawing, but these are the same as those of the embodiment of FIG. Of course, it also comes with things. Further, at least one end of the vibration regulating member 12 is fixed by a fixing means (not shown) so that the vibration is regulated.

Next, the operation of the apparatus shown in FIG. 4 will be described. First, regarding the operation of vibrating the charging member, the same operation as in the case of the embodiment of FIG. 2 described above is performed.
On the other hand, in the device shown in FIG. 4, since the vibration regulating member 12 is penetratingly held and at least one end thereof is fixed, the vibration of each fiber of the conductive fibers 4 constituting the charging member by the vibrating means 8 is regulated. The tooth-shaped side surface of the comb of the member 12 is regulated as if it collides with each vibration. For this reason, once the residual developer on the surface of the image carrier 2 adheres to the fibers 4, once adhered, it is hard to drop off in the past.
This causes streaky uneven charging or damage to the surface of the image bearing member 4. However, by using both the vibration and the vibration regulation as described above, the residual developer is wiped off, and all of the above problems occur. Will be resolved.

Finally, the effects of the present invention will be more clearly described with reference to specific examples. When copying is performed with the apparatus having the configuration as shown in FIG. 2 but with the vibration kept OFF and the charging member is in contact with the image carrier, charging is started in the paper feeding direction after the number of copying exceeds 5,000 sheets. Unevenness occurs, about 10,
Uneven charging occurred on almost the entire surface of the paper copied at 000 sheets. Also, the density was relatively low around 5,000 sheets, but it became quite dark around 10,000 sheets. On the other hand, when the apparatus having the configuration of FIG. 2 or the configuration of FIG. 4 is used and vibration of 60 Hz is applied, a good image without uneven charging can be obtained up to 20,000 copies in any configuration. It becomes possible, especially when the vibration regulating member 12 having the configuration of FIG.
Contamination of the conductive fiber 4 was small even when the number of sheets exceeded 10,000.

[0015]

EFFECTS OF THE INVENTION When a brush-shaped charging member made of conductive fibers is used in a charger, uneven charging occurring in the paper feeding direction is prevented, and wear of the brush tip and the image carrier is reduced. At the same time, it is possible to provide an electrophotographic copying apparatus capable of solving the problem of developer accumulation on the tip of the brush, which causes contamination, and its effect is immeasurable.

[Brief description of drawings]

FIG. 1 is a perspective view showing a positional relationship between a charger and a photosensitive drum according to the present invention.

FIG. 2 is a conceptual explanatory view showing an embodiment of the configuration of a vibrating means in the present invention.

FIG. 3 is a diagram illustrating timing of a series of operations of a control circuit.

FIG. 4 is a conceptual explanatory view showing an embodiment of the configuration of the vibration regulation means in the present invention.

FIG. 5 is a plan view of a vibration regulation member according to the present invention.

FIG. 6 is a plan view showing a usage state of the vibration regulating member according to the present invention.

FIG. 7 is an explanatory diagram showing a positional relationship between a conventional charger and a photosensitive drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Image carrier 3 Charging device 4 Conductive fiber 5 Charging brush 6 Conductive adhesive 7 Conductive substrate 8 Vibrating means 9 Pulse oscillation circuit 10 Control circuit 11 Repulsion means 12 Vibration regulating member

Claims (4)

[Claims] 1. A brush-shaped charging member made of a conductive fiber is brought into contact with an image carrier, and when the image carrier is electrically charged, the charging member is vibrated in a state of contact with the image carrier. An electrophotographic copying apparatus, characterized in that a means for tightening is provided. 2. A brush-shaped charging member made of a conductive fiber is brought into contact with the image carrier, and when the image carrier is charged, the charging member is vibrated in a state of contact with the image carrier. With means to tighten,
An electrophotographic copying machine characterized in that a comb-shaped vibration regulating member is held through the entire surface of the conductive fiber portion. 3. The electrophotographic copying machine according to claim 1, wherein the vibration direction of the charging member is substantially perpendicular to the rotation direction of the image carrier. 4. The electrophotographic copying apparatus according to claim 1, wherein the vibration cycle of the charging member is 1 Hz or more.