JPH07199601A - Manufacture of contact electrifying device - Google Patents

Abstract

PURPOSE:To reduce uneven surface potential in an initial using state and to attain high image quality by drying a cleaned brush member and also executing a bristle removing processing at the same time. CONSTITUTION:By lowering a brush supporting member by a rotary driving part 17, a brush roller 1 to which the cut or the shaft of fiber surface are stuck is immersed into a container 15 filled with cleaning agent 14 while being slowly rotated by the rotary driving part 17, thereafter, the brush roller 1 is rotated at the same speed so as to be dried in air. The bristle removing processing is executed by inserting the brush roller 1 into a cylindrical container whose diameter is slightly smaller than that of the brush roller and rotating the roller 1 for a fixed time under high temp. and humidity environment, or in high temp. steam. This process is executed after cleaning, then, it is made possible to prevent the performance deterioration of the electrifying device caused by mechanical irregularities in fiber due to the cleaning. And also, by executing the bristle removing processing at the time of drying the cleaned roller, the increase of the number of processes is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a contact charger, and more particularly to a method of manufacturing a contact charger used in electrophotography.

[0002]

2. Description of the Related Art Conventionally, a corona discharger using a scorotron has been mainly used as a charging device for electrophotography. But,
Charging with a corona discharger uses the discharge phenomenon,
In particular, negatively charged ozone produces harmful ozone to the human body.
In addition, the applied voltage is relatively high at -4 to -5 kV, and most of the current flows into the case, resulting in a large energy loss.

In recent years, a contact charging technique in which almost no ozone is generated has been developed in place of corona charging. Typical examples are a roller charging method, a brush charging method, and a blade charging method. When these contact charging methods are used, the amount of ozone generated is 1/100 or less of that of corona charging, the applied voltage is as low as -1 kV, and the current loss is small. However, immediately after the first use of an electrophotographic device such as a printer or a copying machine using a contact charger, or immediately after exchanging a process cartridge, the image quality such as halftone is significantly deteriorated in the formation of the first few images. There is a problem that it ends up. This phenomenon is peculiar to a device using a contact charger, and is considered to be caused by the following.

That is, the contact charger is set in a process unit or the like from the time of shipment from the factory and left for a long time in a state of being in contact with the photoconductor. In this case, if the contact surface of the contact charger with the photoconductor is not clean, dirt or impurities will adhere to the photoconductor, and that portion will become a memory in the initial image, or the surface potential for the initial several tens of seconds will increase. It becomes unstable.

Further, in the conductive brush charger, there is a cause of unstable initial surface potential in addition to surface contamination.
This is thought to be due to the following reasons. In the process of manufacturing the brush charger, the surface is cut to make the charged surfaces uniform. By this step, the oil of the cutter adheres to the surface of the fiber, and at the same time, the cut surface of the brush fiber becomes rough at the microscopic portion, resulting in breakage and split ends.

When the brush charger is used in this state, the conductive carbon comes into contact with the photosensitive member more in the microscopic area, so that a charging phenomenon (which is called charge injection) which does not depend on Paschen's discharge occurs. Or, the discharge concentrates on excessively thin fibers or fibers existing apart from other fibers, causing the surface potential to rise in an unstable manner.

This phenomenon occurs only in the first few prints and stabilizes immediately. However, the use of a brush charger causes irreversible changes such as rapid oxidation on the fiber surface. This is probably because the insulating layer on the fiber surface becomes thick, or the discharge concentrates and the excess fiber burns out.

[0008]

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances and provides a method of manufacturing a contact charging device capable of reducing unevenness of surface potential in an initial use state and achieving high image quality. To aim.

[0009]

The present invention (Claim 1) includes:
A method of manufacturing a contact charging device, comprising a brush-shaped member, for charging the surface of an image bearing member by contacting the surface of the image bearing member, the method comprising: cleaning the contact charging surface of the brush-shaped member; And a step of simultaneously subjecting the member to a slant treatment, and a method of manufacturing a contact charging device.

The present invention (Claim 2) is characterized in that, in the above method (Claim 1), the brush-shaped member contains conductive fibers, and a bias is applied to the brush-shaped member in the process of treating the bristles. A method of manufacturing a contact charging device is provided. Furthermore, the present invention (Claim 3) is a method of manufacturing a contact charging device which has a brush-like member and charges the surface of the image bearing member by contacting the surface of the image bearing member. And a step of heat-treating the brush-like member at a temperature T ₁ satisfying the following formula after the cutting.

2T ₂ (° C.) ≧ T ₁ (° C.) ≧ 2 / 3T ₂ (° C.) T ₂ : melting point (° C.) of the material of the brush-like member Furthermore, the present invention (claim 4) provides the above method ( In claim 3, the heat treatment provides a method for manufacturing a contact charging device, characterized in that a brush-like member is pressed against a heated member.

[0012]

According to the method of manufacturing the contact charging device of the present invention (claim 1), the contact charging surface of the brush-like member is washed, and the washed brush-like member is dried, and at the same time, the slanting treatment is performed. . When the contact charging surface of the brush-like member is washed, impurities such as a lubricant used during cutting are removed from the surface of the brush fiber, thereby reducing the initial potential rise and uneven charging. In addition, since the hair shaving treatment is also performed in the drying step at the same time, it is possible to prevent performance deterioration of the charger due to mechanical disturbance of the fibers due to washing with a small number of steps.

In the method for manufacturing a contact charging device of the present invention (claim 2), a bias is applied to the conductive brush-like member in the slant treatment step. By doing so, an irreversible change can be intentionally generated on the fiber surface, and the potential can be further stabilized.

In the method of manufacturing the contact charging device of the present invention (claim 3), the brush-shaped member is heat-treated in a predetermined temperature range after cutting the tips of the brush-shaped members. By such heat treatment, irreversible changes such as oxidation can be generated on the fiber surface without the brush fibers melting, and the thin waste hairs that cause excessive charging are burned out to reduce the surface potential. It is possible to improve stability.

In the method for manufacturing the contact charging device of the present invention (claim 4), the heat treatment is performed by pressing the brush-shaped member against the heated member. By such heat treatment as well, the stability of the surface potential can be improved, and the bristle surface of the contact charger can be processed according to the shape of the photoconductor to be brought into contact.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a brush charger as a contact charger manufactured by the method of the present invention. As fibers constituting this brush charger, fibers in which carbon was dispersed in rayon (fiber diameter: 10 to 50 μm, density: 50,000 to 200,000 / cm ² ) were used. There are two types of brush chargers, which are used by rotating them relative to the photoconductor.
There are a brush roller charger 1 shown in FIG. 1 (a) and a fixed brush 7 shown in FIG. 1 (b) which is used by being attached to a fixed support member.

In the manufacturing process, these brush chargers are knitted on a conductive base fabric by various methods. After that, in the case of a brush roller, the base cloth is wound around a metal shaft, and in the case of a fixed brush, the base cloth is adhered to a supporting member to manufacture.

Here, in the state where the conductive fiber is woven on the base cloth, the fiber tip surfaces are not aligned in parallel and are cut at the hair tip surface before and after bonding to the metal shaft or the supporting member. A step of aligning the bristle tips is required. Usually, in this step, as shown in FIG. 2, a base fabric 10 in which conductive fibers 9 are woven is attached to a cylindrical drum 11, and the drum 11 or a cutter 8 provided is rotated to evenly cut the bristle surface. To do.

It should be noted here that a lubricant such as oils and fats is attached to the cutter 8 for smooth cutting, and this lubricant adheres to the surface of the cut fiber in a small amount. , Will contaminate the charged surface.

FIG. 3 shows the result of initial measurement of the surface potential by the brush roller charger prepared by the conventional manufacturing method.
A reversal development type dry electrophotographic laser printer (printing speed 8 sheets / minute) was used for the experiment, and the brush roller had a diameter of 1
The resistance was 10 ⁵ to 10 ⁶ Ω, the peripheral speed was Against 2: 1 with respect to the photoconductor, the bite amount of the brush charger was about 0.5 mm, and the applied bias was DC-1 kV.

The measurement was carried out by setting a surface potential sensor on the exposure section 3 shown in FIG. 1A and printing a halftone image using two types of toner, toner A and toner B. In the graph of FIG. 3, the solid line 101 indicates the case where the toner A is used for printing, and the dotted line 102 indicates the case where the toner B is used for the printing.

From the graph of FIG. 3, it can be seen that when the brush charger is new, the surface potential rises by several tens to one hundred and several tens of volts in the initial 60 seconds or so compared with the normal case.
Further, in the printing using the toner B, a memory is generated in a portion where the photoconductor and the charger have been in contact with each other for a long period of time, and density unevenness in the photoconductor cycle appears in an image.

Therefore, before using the brush charger 1,
The brush charger 1 was washed by the following method. That is, as shown in FIG. 4, by lowering the brush support member by the rotation driving unit 17, the brush roller 1 whose fiber surface has been cut or adhered to the shaft is placed in the container 15 containing the cleaning agent 14. 3 minutes for rotation drive 17
Was slowly dipped while rotating at a speed of 60 rpm, and then dried in air at a similar speed in an environment of about 60 ° C.

As the cleaning agent, a surfactant, ethanol, and water were used, and only when the surfactant was used, a step of immersing in a container containing water was added after that. In addition, an experiment in which ultrasonic cleaning was performed as a cleaning step was also performed separately.

With respect to the brush roller charger 1 thus washed, the surface potential of the photoconductor in the initial state was measured and halftone printing was performed, and the results shown in FIGS. 5 and 6 were obtained. According to FIG. 5 and FIG. 6, washing with water (dashed line 103 in FIG. 5) was not much different from that without washing (dashed line 102 in FIG. 3), but using a surfactant or ethanol (Dotted line 104, solid line 1 in FIG. 5
In 05), the rise in surface potential decreased and the memory could not be seen.

Further, it is more preferable to use ultrasonic cleaning for the brush subjected to ultrasonic cleaning (curves 106 to 108 in FIG. 6) and the brush subjected to simple cleaning (curves 103 to 105 in FIG. 5). A good effect was obtained. That is, it is understood that by using these cleaning agents, impurities that are difficult to be removed by simple water can be cleaned from the surface of the brush fiber, and it is possible to reduce the initial potential rise and uneven charging.

In the manufacturing process of the brush roller charger,
When the conductive fibers 9 are sewn onto the base cloth 10, the fibers cannot be usually planted on the edge portion of the base cloth 10 in order to prevent the fibers from coming off, and the state shown in FIG. When the base cloth 10 is wound around the metal shaft 12 in this state, regular windings 21 are formed as shown in FIG. 7B, and a partial difference occurs in the fiber density. Then, when a high-definition image is printed in this state, a curl streak is diagonally generated on the image.

In the usual brush roller manufacturing process, in order to make it inconspicuous and to make the fibers evenly contact the photoconductor, a shaving process is carried out at the final stage. As shown in FIG. 8 (a), the usual fluff treatment is performed by inserting a brush roller into a cylindrical container having a diameter r _{2 which} is slightly smaller than the brush roller diameter r ₁ and then in a hot and humid environment or in a steam at a high temperature. , By rotating for a certain period of time. By performing this step after washing, it is possible to evenly incline the reversely fluffed fibers by washing and prevent the performance of the charger from being deteriorated due to mechanical disturbance of the fibers due to washing. In the present invention, this hair-slanting treatment is performed at the same time as drying during washing, and by doing so, an increase in the number of steps can be avoided.

In the experiment, while the brush roller wound around the shaft 12 was rotated at a speed of 60 rpm, the brush roller was immersed in a surfactant or an organic solvent for 3 minutes, and then they were pulled up to a size smaller than the brush roller diameter (17 mm). It was inserted into a cylindrical container 13 having an inner diameter (15 mm), and while the cylinder 13 was fixed, it was dried at 60 ° C. for 30 minutes while rotating the brush roller in the direction of the arrow shown in FIG. 8B at a speed of 60 rpm.

Using the brush roller charger prepared as described above, the surface potential was measured and halftone printing was performed. As a result, the results shown in FIG. 9 were obtained. From the graph shown in FIG. 9, in the brush roller that was subjected to the bristling process in addition to the cleaning (in the graph, the solid line 109 and the dotted line 110), the mechanical contact state of the fibers with the photoconductor became uniform, and immediately after the start of energization. The surface potential rise of the above is so far (curves 102 to 1
It can be seen that the charging characteristics are improved as compared with 08).

As described above, by using the method of the present invention, it is possible to print a good image having no initial charging unevenness and no winding streaks from the beginning of use. Next, the surface potential is unstable when the contact charger is used for the first time, and the potential is stable when electricity is applied for a certain period of time thereafter.Therefore, electricity treatment is performed in advance in the manufacturing process to irreversibly change the fiber surface. An experiment was conducted by intentionally generating a voltage to stabilize the potential.

In the experiment, the cylindrical container 13 used when the brush roller charger, which has been washed with the surfactant, is subjected to the slant treatment.
Is made of aluminum, and the cylindrical container 13 is grounded to the GND as shown in FIG.
2 was applied by applying a bias. here,
Since the fluffing treatment atmosphere is a high temperature environment and contains a large amount of solvent and moisture, when constant voltage control is performed, the current flowing through the brush fibers fluctuates significantly depending on the amount of moisture and the like.
Therefore, the applied bias is constant current control (current value 100 μA
10 mA) so that the high voltage is applied only when the fiber is dried.

Further, as shown in FIG. 11, the energization was not carried out in the first half of the hair-slanting process, but was carried out only in the latter half of 15 minutes when the drying was relatively advanced. Using the brush roller charger manufactured in this way, the surface potential was measured by the same method as before, and the results shown in FIG. 12 were obtained. In the graph of FIG. 12, the solid line 111 further improves the stability of the surface potential as compared with the case of the dotted line 110 shown in FIG. 9 in which no bias is applied. Further, even when a bias is only applied during the hair-shaping process without washing (dotted line 113), the stability of the potential is improved as compared with the case where no countermeasure is taken (dotted line 102 in FIG. 3). It turns out that is effective independently of.

Next, a method of treating the brush charger at a high temperature will be described. The brush charger used in the experiment was made of rayon (melting point 160 ° C) and nylon type with carbon embedded (nylon has melting point 178).
C. and 255.degree. C.), a total of three types, and a fixed brush having a width of 5 mm was used. The printer, the potential measuring method, and the like are all the same as in the above experiment. The high temperature treatment has a melting point of 16
100 ℃ to 150 ℃ for 0 ℃, 100 ℃ to 170 ℃ for melting point of 178 ℃,
When the melting point was 255 ° C., the temperature was raised from 130 ° C. to 250 ° C., and the whole was left for 10 minutes.

FIG. 13 shows the result of measuring the surface potential using the brush charger which has been subjected to such a high temperature heat treatment. The following can be seen from the graph of FIG. That is, in the brush charger having a melting point of 160 ° C. (FIG. 13A), no change in the surface potential characteristics was observed at a temperature of about 100 ° C., but at 110 ° C. or higher, the initial surface potential was slightly stable. Come on. However, at 150 ° C., the fibers are partially deformed and the image quality is disturbed this time.

Further, in the brush charger having a melting point of 178 ° C. (FIG. 13B), when the temperature was changed from 110 ° C. to 170 ° C., the effect was observed at 130 ° C. or higher,
At 170 ° C, the brush partially melts and the image quality deteriorates. Further, the melting point is 255 ° C. (FIG. 13 (c))
Then, the effect was recognized at about 170 ° C. That is, it is possible to slightly improve the surface potential stability by heat-treating the brush charger at a temperature of ⅔ or more of the melting point, and it is desirable to heat the brush charger at a temperature of about 80 to 90% of the melting point. I understand. This temperature range is a region immediately before the fibers are melted, because irreversible changes such as oxidation occur on the fiber surface, and only the fibers in the thin waste state have burned out and disappeared. Conceivable.

The brush charger may be exposed to a temperature exceeding the melting point of the brush fibers for a short time. In Figure 14,
The results obtained when the brush charger is exposed to a temperature above the melting point for 1 to 5 seconds are shown. In this experiment, a brush charger having a melting point of brush fiber of 178 ° C. was used, and the exposure environment was 20.
Performed at 0 ° C. According to these results, the initial surface potential tends to be stable when exposed for 2 to 3 seconds or more, but when exposed for 5 seconds or more, the fibers are partially melted to become dusty and the unevenness on the image increases. have done.

The optimum exposure time depends on the melting point of the fiber and the exposure environment (mainly the temperature), and is shown in the graph of FIG. Thus, the initial stability of the surface potential can also be improved by exposing the fiber to a temperature above the melting point for a short time. That is, when the brush charger is exposed to a high temperature environment above the melting point for a short time, the surface portion including the fiber tip is slightly melted, and an insulating layer is formed on the charged surface. It is conceivable that the waste hair that has become worn out will melt and disappear.

Further, as a treatment method which can obtain the same effect as the high temperature heat treatment described above, a method of pressing a contact charger such as a brush charger against a member such as a metal heated above the melting point of the fiber can be considered. The outline is shown in FIG. FIG. 15A shows a member 21 heated by a heater 22 (in the experiment, an iron plate having a Teflon surface is used)
It is a conceptual diagram which presses the fixed brush charger 7 to. FIG. 15B shows a state where the same curvature member as that of the photoconductor is used and the brush charger 7 is pressed against the same, and FIG.
Is a drum member 21 having the same diameter as that of the photoconductor drum, and the brush charger 7 is pressed against the drum member 21 while rotating the drum member 21.

According to these methods, it is possible to uniformly melt only the surface of the charger, that is, the charged surface, and to eliminate extra fibers such as cut hairs and split ends. Further, by using a heating member as shown in FIG. 15 (b) or FIG. 15 (c), the shape of the charging surface can be freely controlled, and the contact charger can be adjusted according to the shape of the photoconductor to be brought into contact. It is also possible to process the bristle tip surface.

FIG. 16 shows the initial charging characteristics of the charging brush which has been heat-treated by the method shown in FIG. 15 (c). About 200 ℃ heating element for brush fibers with a melting point of 178 ℃
Cylinder that is heated to the same temperature as the photoconductor used and has a Teflon coating with a diameter of 30 mm is the same speed as the printer (peripheral speed is about 50 mm.
/ Sec) and rotate the brush charger to 2 mm.
It was pressed so as to bite in about, and after about 3 seconds, it was released from the heating member.

According to FIG. 16 (solid line 120), FIG.
The charging brush subjected to the heat treatment by the method shown in (c) is
It can be seen that the initial potential is more stable than in the untreated state. As described above, it can be confirmed that the same effect is obtained by the method shown in FIG. Also in this method, the optimum value of the heating time varies depending on the melting point of the brush fiber and the heating temperature.
As shown in.

From FIG. 17, in the case of a brush fiber having a melting point of 178 ° C., a heating temperature of 200 ° C. is suitable for about 3 seconds, a heating temperature of 250 ° C. is less than 2 seconds, and a heating temperature of 3 seconds.
At 00 ° C., it took about 1 second, and at 370 ° C., the tips of the hairs shattered in an instant in the experiment, and good results were not obtained. Similarly, in the case of the brush fiber composed of a material having a melting point of 255 ° C., good results were obtained only up to around 500 ° C. That is, it is understood that the upper limit temperature of the heat treatment is about twice the melting point.

Further, these heating members do not necessarily have to be heated to a temperature exceeding the melting point of the brush fibers,
As described above, a certain effect can be obtained by setting the temperature to ⅔ or more of the melting point and pressing it for several minutes. According to the dotted line 121 in FIG. 16, the heating temperature is 150 ° C.
A certain effect can also be recognized by pressing the brush charger for 8 minutes.

The above description can be similarly applied to both the brush roller and the fixed type brush charger. That is, in the case of a fixed brush charger, the sloping treatment is not common, but it is effective in improving the contact state of the fibers with respect to the photoconductor. In addition, by performing cleaning and energizing treatment in the final step without performing the hair-slanting treatment, it is possible to solve the problems of initial charging unevenness and potential rise.

Further, another type of contact charger, for example, the conductive blade 1 shown in FIGS. 18 (a), 18 (b) and 18 (c).
The same applies to 8, the conductive sponge 19, the conductive roller 20, and the like. By performing a cleaning process in the final step of manufacturing these contact chargers, stains attached to the charged surface can be removed, and a good image can be obtained from the initial stage even after being left in contact with the photoconductor for a long time. It will be possible.

[0047]

As described above, according to the present invention,
By cleaning the contact charging surface of the brush-like member that constitutes the contact charger, drying the washed brush-like member, and at the same time subjecting the brush-like bristles to the conductive brush-like member, By applying a bias, after cutting the bristle tips of the brush-like member, the brush-like member is heat-treated in a predetermined temperature range, thereby performing heat treatment by pressing the brush-like member against the heated member. As a result, it is possible to reduce the initial potential rise and uneven charging.

[Brief description of drawings]

FIG. 1 is a view showing a brush charger as a contact charger manufactured by the method of the present invention.

FIG. 2 is a view showing a state in which a bristle tip surface of a brush roller charger is cut.

FIG. 3 is a characteristic diagram showing measurement results of initial surface potential by a brush roller charger prepared by a conventional manufacturing method.

FIG. 4 is a diagram showing a cleaning process of a brush roller.

FIG. 5: Regarding the brush roller charger after cleaning,
FIG. 6 is a characteristic diagram showing the results of measuring the surface potential of the photoconductor in the initial state and performing halftone printing.

FIG. 6 is a characteristic diagram showing a result of performing surface tone measurement and halftone printing on a photoconductor in an initial state with respect to a brush roller charger that has been subjected to ultrasonic cleaning.

FIG. 7 is a diagram showing a partial difference in the fiber density of the brush roller.

FIG. 8 is a diagram showing a process of slanting a brush roller.

FIG. 9 is a characteristic diagram showing a result of performing surface potential measurement and halftone printing by using a brush roller charger that has been subjected to bevel treatment.

FIG. 10 is a diagram showing a state in which a bristling process is performed while applying a bias to the brush roller.

FIG. 11 is a characteristic diagram showing the relationship between the time for treating the slanted hair and the application of a bias.

FIG. 12 is a characteristic diagram showing a result of surface potential measurement performed by using a brush roller charger manufactured by applying a bias in the middle of the bristling process.

FIG. 13 is a characteristic diagram showing the results of surface potential measurement using a brush charger that has been subjected to high temperature heat treatment.

FIG. 14 is a characteristic diagram showing the results of surface potential measurement using a brush charger that has been exposed to a temperature exceeding the melting point for 1 to 5 seconds.

FIG. 15 is a diagram showing a method of pressing a brush charger against a member heated to a temperature equal to or higher than the melting point of the fiber.

FIG. 16 is a characteristic diagram showing an initial charging characteristic of a charging brush that has been heat-treated by a pressing method.

FIG. 17 is a characteristic diagram showing the relationship between heating temperature and pressing time.

FIG. 18 is a diagram showing a contact charger of a type other than a brush.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Brush roller charger 2 ... Photosensitive body 3 ... Exposure 4 ... Electrification light 5 ... Development roller 6 ... Cleaner (blade) 7 ... Fixed brush charger 8 ... Cutter 9 ... Brush fiber 10 ... Base cloth 11 ... Drum 12 ... Metal shaft 13 ... Slanted cylindrical container 14 ... Cleaning agent 15 ... Cleaning container or ultrasonic cleaner 16 ... Brush support member

Claims (4)

[Claims] 1. A method of manufacturing a contact charging device having a brush-shaped member, which charges the surface of the image carrier by contacting the surface of the image carrier, the method comprising: cleaning a contact charging surface of the brush-shaped member. , While drying the washed brush-like member,
At the same time, a process for treating hair is provided. 2. The brush-shaped member includes conductive fibers,
The method of manufacturing a contact charging device according to claim 1, wherein a bias is applied to the brush-shaped member in the slant treatment step. 3. A method of manufacturing a contact charging device, comprising a brush-shaped member, for charging the surface of the image-bearing member by contacting the surface of the image-bearing member, the brush being after cutting the tips of the brush-shaped member. A method of manufacturing a contact charging device, comprising a step of heat-treating the sheet-shaped member at a temperature T ₁ satisfying the following formula. 2T ₂ (° C) ≥ T ₁ (° C) ≥ 2 / 3T ₂ (° C) T ₂ : melting point (° C) of material of brush-like member 4. The method of manufacturing a contact charging device according to claim 3, wherein in the heat treatment, a brush-shaped member is pressed against a heated member.