JPH08137289A - Image forming device - Google Patents

Abstract

PURPOSE: To obtain an excellent image without an image defect due to the transfer unevenness, the transfer missing or the like, by providing a defect detection device to come into contact with a transfer material carrier member, and quickly detecting the defect of the transfer material carrying member. CONSTITUTION: In the defect detection device 29, the defect detection of the transfer material carrier member such as a pin-hole is performed by holding the conductive defect detection members 29a and 29b in contact with the transfer material carrier member 11, applying the AC voltage from the power source 29c and monitoring the current change of the defect part and the non-defect part. Namely, after completing the cleaning of the transfer material carrier member 11 surface, a pair of defect detection device 29 in the roller shape are held in contact with the transfer material carrier member 11, and the change of current is monitored while applying the AC voltage. At this time, if there is the defect such as a pin hole on the transfer material carrier member 11, the current value is sharply increased. Accordingly, the detected part is set as the non-image part, that is, the place where the transfer material is not transported at the next image forming process time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer material carrier and an image forming apparatus, and more particularly to transferring a toner image formed on the image carrier by an electrophotographic method or an electrostatic recording method onto a transfer material. The present invention relates to a transfer material carrying member and an image forming apparatus having the transfer material carrying member. As such an image forming apparatus, there are black-and-white, mono-color or full-color electrophotographic copying machines, printers, and other various recording devices.

[0002]

2. Description of the Related Art Conventionally, there are various types of transfer material carrying members used for transferring an image on an image carrier to a transfer material. For example, charging-image exposure-toner development-
In an electrophotographic apparatus having an image forming means such as transfer-cleaning, a transfer drum and a transfer device as shown in FIG. 1 are examples of means for transferring a toner image on a photoconductor to a transfer material (for example, paper).

The transfer drum 10 has a transfer material carrying member 11 stretched around the outer peripheral surface of a cylindrical support. Further, the transfer discharger 2 is provided inside and outside the transfer drum 10.
1, and an inner charge-eliminating discharger 23 and outer charge-eliminating dischargers 22, 24, which constitute the charge-eliminating means.

In the transfer step, various external mechanical or electrical forces such as transfer of the transfer material, transfer charging, charge removal and cleaning are applied to the transfer material carrying member 11, so that durability against these external forces, that is, mechanical strength, Various properties such as excellent wear resistance, electrical durability, and excellent lubricity for cleaning members are required.

In order to further improve the image quality, it is necessary to improve the transferability of the toner image onto the transfer material (for example, paper) in order to improve the reproducibility of the latent image.

Conventionally, a resin film having a relatively high electric resistance such as Teflon, polyester, polyvinylidene fluoride, triacetate and polycarbonate has been used as a transfer material carrying member.

When these resin films are used as a transfer material-carrying member, increasing the transfer charging strength is an effective method for improving the transferability, but the electrical durability of the transfer material-carrying member is high. There was a problem that it became more severe.

Further, in order to improve such a drawback,
As disclosed in JP-A-60-10625,
Attempts have been made to disperse carbon black in the resin used for the transfer material carrying member to arbitrarily control the volume resistance of the resin film. However, it is very difficult to uniformly disperse the conductive particles such as carbon black in the resin, and the resistance value in the minute portion is non-uniform due to poor dispersion of the conductive particles such as carbon black. Often. When this film was used as a transfer material carrying member, the resistance of the film was non-uniform, and there was a problem in electrical durability such as dielectric breakdown.

As described above, no matter which film is used for the transfer material carrying member, there remains a problem in electrical durability. If the transfer material carrying member that has caused a dielectric breakdown even in part is repeatedly used as it is, electric charges are injected through the dielectric breakdown portion, which disturbs the toner image or causes dielectric breakdown of the photosensitive drum. ,
It was necessary to detect defects in the transfer material carrying member as soon as possible.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to detect a defect of a transfer material carrying member as soon as possible, and to obtain a good transfer material carrying an image free from image defects due to transfer unevenness or transfer gap. An object of the present invention is to provide a member defect detection device and an image forming apparatus using the same.

[0011]

In order to solve the above-mentioned problems, the defect detecting device of the present invention is characterized in that it is provided so as to be in contact with a transfer material carrying member.

Since the defect detecting device 29 of the present invention detects defects such as pinholes in the transfer material carrying member, conductive defect detecting members 29a and 29b are provided on the transfer material carrying member 11 as shown in FIG. Contact is made, a DC voltage is applied from the power source 29c, and current changes in the defective portion and the non-defective portion are monitored. In the figure, 29d is a protection circuit.

The applied DC voltage value must be lower than the withstand voltage of the transfer material carrying member, preferably 3 kV.
The following settings are desirable. As the direct current applying means, either the constant voltage method or the constant current method can be used.
The constant voltage method is preferable from the viewpoint of response of defect detection.

The shape of the conductive defect detecting member used in the defect detecting apparatus of the present invention is not limited to the roller shape shown in FIG. 1, but may be a blade shape, a rotating belt shape, a brush shape, a piece shape, or conductive particles. Examples include the magnetic brush used.

From the viewpoint of detection efficiency, it is preferable that the conductive defect detecting member used in the present invention has a resistivity of 10 ¹⁰ Ω · cm or less.

The material of the conductive defect detecting member used in the present invention is a metal such as aluminum, iron or copper, a conductive polymer such as polyacetylene or polypyrrole, an insulating resin such as polycarbonate or polyester, or a rubber surface. It is possible to use those laminated or coated with a metal and another conductive substance, or those in which conductive particles such as carbon black are dispersed in a binder resin to control the conductivity.

Further, examples of the material of the transfer material carrying member used in the image forming apparatus of the present invention include resin films such as polyvinylidene fluoride, triacetate and polycarbonate.

Further, as the material of the transfer material carrying member used in the image forming apparatus of the present invention, a resin film containing a conductive carbon black in a silicone-modified polycarbonate resin is more preferable from the viewpoint that electric resistance can be arbitrarily controlled.

This silicon-modified polycarbonate resin has the advantage that the dispersibility of the conductive carbon black is good.

The copolymerization ratio of silicon in the silicone-modified polycarbonate resin is preferably 0.5 to 30% by weight.

The content of the conductive carbon black is 0.1 to 30 parts by weight with respect to 100 parts by weight of the transfer material carrying member used in the image forming apparatus of the present invention so that the dispersibility and resistance can be controlled. It is preferable from the point.

A concrete example of the aspect of the image forming apparatus having the defect detecting apparatus of the present invention is shown in FIGS. The image forming apparatus shown in FIGS. 2 and 3 is an example of a multicolor (full color) image forming apparatus.

First, a brief description will be given with reference to FIG. Figure 2
In the multicolor electrophotographic copying machine shown in FIG. 1, an image carrier, which is rotatably supported and rotatable in the direction of arrow a, that is, a photosensitive drum 33 is arranged, and an image forming means is arranged on the outer peripheral portion thereof. The image forming unit may be any unit, but in this example, the primary charger 34 that uniformly charges the photosensitive drum 33.
On the photosensitive drum 33, and an exposure means 32 including, for example, a laser beam exposure device for forming an electrostatic latent image on the photosensitive drum 33 by irradiating a color-separated optical image or an optical image corresponding thereto. And a rotary developing device 31 for converting the electrostatic latent image into a visible image.

The rotary developing device 31 includes four developing devices 31 for accommodating four color developers of yellow color developer, magenta color developer, cyan color developer and black color developer, respectively.
It is composed of Y, 31M, 31C, 31Bk, and a substantially cylindrical casing that holds these four developing devices and is rotatably supported. The rotary developing device 31 conveys a desired developing device to a position facing the outer peripheral surface of the photosensitive drum 33 by the rotation of the casing, develops the electrostatic latent image on the photosensitive drum, and performs full color for four colors. It is configured to enable development.

A visible image on the photosensitive drum 33, that is,
The toner image is transferred to the transfer material P carried by the transfer device 10 and conveyed. In this example, the transfer device 10 is a transfer drum that is rotatably supported.

The process of forming a full-color image by the multicolor electrophotographic copying apparatus having the above-mentioned structure will be briefly described below.

After the photosensitive drum 33 is uniformly charged by the primary charger 34, the exposure means 32 irradiates the optical image E according to the image information to form an electrostatic latent image on the photosensitive drum 33. . The electrostatic latent image is visualized as a toner image by the rotary developing device 31 on the photosensitive drum 33 with toner using resin as a base material.

On the other hand, the transfer material P is sent to the transfer drum 10 by the registration rollers 36 in synchronism with the image, the tip of the transfer material P is gripped by the gripper 15 and the like, and is conveyed in the direction of arrow b in the figure.

Next, in the area contacting the photosensitive drum 33, the transfer drum 10 receives a corona discharge having a polarity opposite to that of the toner from the back surface of the transfer material carrying member 11 by the transfer discharger 21 to form a toner image on the photosensitive drum 33. Are transferred to the transfer material P.

After the transfer process has been performed the required number of times, the transfer material P is separated from the transfer drum 10 by the action of the separation claw 28 while being discharged by the discharging discharging devices 22, 23 and 24, and is fixed by the conveying belt 38. After being fixed by heat in the container 39, it is discharged to the outside of the machine.

On the other hand, after the residual toner on the surface of the photosensitive drum 33 is cleaned by the cleaning device 37, the photosensitive drum 33 is subjected to the image forming process again.

Further, the transfer material carrying member 1 of the transfer drum 10
Similarly, a cleaning device 35a having a blade, a fur brush or the like on one surface and a cleaning assisting means 3 are also provided.
After being cleaned by the action of 5b, it is again subjected to the image forming process.

In the present invention, after the cleaning of the surface of the transfer material carrying member 11 is completed, a pair of roller-shaped defect detecting devices 29 come into contact with the transfer material carrying member 11 to apply a DC voltage to change the current. To monitor. At this time, if the transfer material carrying member 11 has a defect such as a pinhole, the current value rapidly increases. Then, since the detected portion is set to a non-image portion, that is, a portion where the transfer material P is not conveyed in the next image forming process, it is possible to obtain a good image without image defects due to transfer unevenness or transfer blanking.

FIG. 3 shows a specific example of an image forming apparatus using a transfer material carrying member when the shape is an endless belt.

The image forming apparatus shown in FIG. 3 has photosensitive drums 41a to 41d around which a primary charger 42a is provided.
-42d, exposing means 43a-43d, developing units 44a-4
4d, transfer chargers 45a to 45d, static eliminator discharger 46a to
46d and 47a to 47d, photosensitive drum cleaning devices 48a to 48d are arranged, an endless belt-shaped transfer material carrying member 40 is arranged below the photosensitive drum so as to penetrate these units, and a urethane blade 49 is provided. A transfer material carrying member cleaning device 50 is arranged.

After the transfer material P'is fed by the paper feed roller, it is conveyed by the endless belt-shaped transfer material carrying member 40 through the transfer section in which the transfer dischargers 45a to 45d are arranged. After the necessary number of transfer steps, the transfer material P ′ is discharged outside the machine after fixing.

After the cleaning of the surface of the endless belt-shaped transfer material carrying member 40 is completed, the roller-shaped defect detection device 29 of the present invention detects defects in the endless belt-shaped transfer material carrying member 40.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0039]

【Example】

(Example 1, Comparative Example 1) Extruded polyvinylidene fluoride (PVDF) film (weight average molecular weight 2000
0, film thickness 150 μm) was used to prepare a transfer drum as shown in FIG.

That is, as the transfer material carrying member 11 shown in FIG. 4, the resin film is used as two aluminum cylinders 1.
A transfer drum 10 was created by stretching the space between Nos. 2 and 13. Both ends of the transfer material carrying member 11 were fixed on a connecting portion 14 connecting the two aluminum cylinders 12 and 13 constituting the transfer drum 10.

In this embodiment, the transfer drum 10 has a diameter of 160 mm and a moving speed of 160 mm / sec. At the same time, the process speed, which is the moving speed of the photosensitive drum 33 and the like, was also set to 160 mm / sec. or,
The opening width of the transfer corona discharger 21 is 19 mm, and the distance between the discharge wire 25 and the outer peripheral surface of the photosensitive drum 33 is 10.
Discharge wire 25 and transfer corona discharger 21 to 5 mm
The distance from the bottom of the shield plate was set to 16 mm. A polyethylene terephthalate resin film was used as the pressing member 27.

In the present embodiment, the inventors of the present invention form a latent image on the photosensitive drum 33 which is charged with a negative polarity by an image forming apparatus as shown in FIG. 2 and uses toner having an average particle diameter of 8 μm. A toner image was obtained by reversal development. This time,
The toner is composed of a resin as a coloring material and a small amount of an additive for improving charge controllability and lubricity, and is negatively charged by being triboelectrically charged with carrier particles in a developing device.

Then, the toner image was transferred onto a transfer material by the transfer device having the above-mentioned structure. Then, the transfer material was separated from the transfer drum 10 and fixed by a fixing device.

In this embodiment, the surface of the transfer material carrying member 11 of the transfer drum 10 has a cleaning device 35a having a urethane blade, and a cleaning assisting means 35b.
To clean.

After cleaning, chlorobrene rubber 100
Conductive defect detection member (volume resistivity = 2 × 10 ⁷ Ωc) formed by melting and kneading 5 parts of conductive carbon into a part and passing through a stainless steel shaft in the center to form φ30 × 340 mm.
A direct current voltage of 1500 (V) was applied to the defect detection device consisting of m) and the current change was monitored. Then, a sequence is adopted in which the space between the abnormal current flows is the paper interval.

The multicolor electrophotographic copying machine having the above-mentioned structure (Example 1) and the multicolor electrophotographic copying machine having no defect detection device (comparative example) were subjected to an image output durability test of 80,000 sheets. As a result, in the device equipped with the defect detection device, a good image without transfer unevenness and transfer missing was obtained even after the endurance, whereas in the copying machine without the defect detection device, image defects such as transfer unevenness were observed. It occurred in several places.

(Example 2, Comparative Examples 2 and 3) 100 parts of silicon-modified polycarbonate (weight average molecular weight 28,000, silicon copolymerization ratio 5% by weight) and specific surface area 800
m ² / g (manufactured by Ketjen Black International Co.) of Ketjen Black EC 5 parts was pelletized with a twin-screw vented extruder. The obtained pellets were compression molded to form a resin film having a thickness of 100 μm. A transfer material carrying member was produced from the obtained resin film in the same manner as in Example 1.

Then, the voltage applied to the defect detection device is set to 5
00 (V) (Example 2) and 3200 (V) (Comparative Example 2)
A durability test was performed in the same manner as in Example 1 except that the above was used. Further, the same durability test was conducted on a multicolor electrophotographic copying machine which is not provided with a defect detecting device (Comparative Example 3). As a result, a defect detection device was attached and the applied voltage was set to 500
With the apparatus set to (V), a good image without transfer unevenness or transfer missing was obtained even after running, whereas in a copying machine without a defect detection device, image defects such as transfer unevenness occurred at several places. did. Further, when the voltage applied to the defect detection device was set to 3200 (V), pinholes were generated in the transfer material carrying member and the photoconductor, and image defects such as black spots and transfer unevenness were observed in a wide range.

(Example 3, Comparative Example 4) The transfer material carrying member was prepared in the same manner as in Example 2.

Next, except that a DC voltage of 200 (V) was applied to a defect detection device (volume resistivity 5 × 10 ⁴ Ωcm), which was composed of a conductive brush in which a large number of carbon fibers were bundled as a conductive defect detection member. A durability test was conducted in the same manner as in Example 1 (Example 3). Further, the same durability test was conducted on a multicolor electrophotographic copying machine which is not provided with a defect detecting device (Comparative Example 4). As a result, in the apparatus equipped with the defect detection device, a good image without transfer unevenness or transfer missing was obtained even after the endurance, whereas in the copying machine without the defect detection device, image defects such as transfer unevenness were observed. Occurred in several places.

(Example 4, Comparative Examples 5 and 6) A resin film prepared in the same manner as in Example 2 was molded into an endless belt, and the same toner as that used in Example 1 and the image forming apparatus shown in FIG. Of toner was used.

Next, as a member for detecting a conductive defect, a surface of a urethane resin blade was coated with a thermoplastic urethane solution containing 5% by weight and 20% by weight of carbon black, respectively. A detector was made. The volume resistivity of each conductive defect detecting member is 1 × 10 ¹² Ωcm (Comparative Example 5), 7 × 10
^{It was 9} Ωcm (Example 4). A DC voltage of 300 (V) was applied to these defect detection devices, and the change in current was monitored. Then, a sequence is adopted in which the space between the abnormal current flows is the paper interval.

A multicolor electrophotographic copying apparatus having the above-mentioned structure (Example 4, Comparative Example 5) and a multicolor electrophotographic copying apparatus having no defect detection device (Comparative Example 6) were used to test the durability of 50,000 images. Was done. As a result, in the apparatus equipped with the defect detection apparatus of Example 4, a good image without transfer unevenness or transfer missing was obtained even after the endurance, whereas in the copying apparatus without the defect detection apparatus, transfer unevenness or the like was obtained. The image defect of No. 1 occurred at several places. Further, in the defect detection device of Comparative Example 5, since almost no change in current was observed, the sequence did not operate normally, and like the copying machine without the defect detection device, image defects such as transfer unevenness occurred at several places. .

Example 5 and Comparative Example 7 100 parts of a polycarbonate resin (weight average molecular weight 32,000) and 5 parts of Ketjen Black EC (manufactured by Ketjen Black International) having a specific surface area of 750 m ² / g were provided with a vent. Pelletized using a screw extruder. The obtained pellets were compression-molded to form a resin film having a thickness of 120 μm. A transfer material carrying member was produced from the obtained resin film in the same manner as in Example 1.

Then, the voltage applied to the defect detection device is set to 1
A durability test was conducted in the same manner as in Example 1 except that the voltage was set to 200 (V) (Example 5). Further, the same durability test was conducted on a multicolor electrophotographic copying machine which is not provided with a defect detecting device (Comparative Example 7).

As a result, in the apparatus equipped with the defect detecting device, a good image was obtained although the transfer unevenness was slightly observed after the endurance, whereas in the copying machine without the defect detecting device, the transfer unevenness was observed. Image defects occurred at dozens of places.

[0057]

As described above, according to the present invention,
By detecting a defect of the transfer material carrying member as soon as possible and setting the detected position in the non-image part, it is possible to obtain a good image without image defects due to transfer unevenness or transfer blanking.

[Brief description of drawings]

FIG. 1 is a schematic configuration example of a transfer device having a defect detection device of the present invention.

FIG. 2 is a schematic configuration example of an image forming apparatus having a defect detection device of the present invention.

FIG. 3 is a schematic configuration example of an image forming apparatus having a defect detection device of the present invention.

FIG. 4 is a structural cross-sectional view of an embodiment of a transfer device having a defect detection device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Transfer device 11 ... Transfer material carrying member 21-24 ... Charger 29 ... Defect detection device 29a, 29b ... Defect detection member 31 ... Developing device 33 ... Photosensitive drum

Claims (7)

[Claims] 1. An image forming apparatus having a transfer material carrying member, wherein a defect detecting device is provided so as to come into contact with the transfer material carrying member. 2. The image forming apparatus according to claim 1, wherein the defect detecting device detects a defect by bringing a conductive defect detecting member into contact with a transfer material carrying member and applying a DC voltage thereto. 3. The defect detecting device detects a defect by bringing a conductive defect detecting member into contact with a transfer material carrying member and applying a DC voltage of a constant voltage system.
The image forming apparatus described. 4. The defect detection device detects a defect by bringing a conductive defect detection member into contact with a transfer material carrying member and applying a DC voltage of 3 kV or less.
The image forming apparatus described. 5. The resistivity of the conductive defect detection member is 1
The image forming apparatus according to claim 1, wherein the image forming apparatus has a resistance of 0 ¹⁰ Ω · cm or less. 6. The image forming apparatus according to claim 1, wherein the transfer material carrying member contains conductive carbon black in a silicone-modified polycarbonate resin. 7. The content of the conductive carbon black is 0.1 to 30 with respect to 100 parts by weight of the transfer material carrying member.
The image forming apparatus according to claim 6, wherein the image forming apparatus is a weight part.