JPH02110581A - Color image forming device - Google Patents

Abstract

PURPOSE:To contrive the facilitation of handling of a photosensitive body at the time of maintenance and the maintenance of a high picture quality extending over a long period by providing a cleaning means for cleaning the end part of the photosensitive body on a process means which is separated from the photosensitive body when the device stops, and approaches the photosensitive body for a prescribed period when the device operates. CONSTITUTION:A blade 134 being a means for cleaning the end part of a photosensitive body is installed on a cleaner 80 being a process means which is usually separated from the photosensitive body and brought into contact with the photosensitive body only when necessary. Therefore, the gap accuracy of the photosensitive body and a developing roller is maintained and a high picture quality can always be maintained by a simple constitution, and also, when the device stops, the blade 134 is separated from the photosensitive body together with the cleaner 8, therefore, the maintenance such as the replacement of the photosensitive body can be executed easily. Moreover, since usually the blade 134 is separated from the photosensitive body, the change of the lapse of time of its elasticity and surface hardly occurs and a stable action can be maintained extending over a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to image forming apparatuses such as color copying machines and color printers that apply electrophotography.

Conventional Technology Conventionally, in copiers, printers, etc. that utilize electrophotography, in order to accurately maintain the gap between the photoreceptor and the developing device, a spacer ring supported at the end of the developing roller coaxially with the developing roller is attached to the photoreceptor drum. The developing device is positioned by touching it. In particular, in recent years, due to the need to simplify and downsize the developing device or to use color, developing devices that develop without contacting the photoreceptor have been actively studied. In this non-contact developing device, this gap accuracy is often required to be higher than in a conventional contact type developing device. Therefore, if toner or dust is attached to the end of the photoreceptor that this spacer ring contacts due to toner scattering inside the machine or other causes, the gap will fluctuate and the image quality will be adversely affected.

Conventionally, in order to prevent such stains and scattering, a sponge or felt has been sandwiched between a photosensitive pair and a member fixed with a certain space in front of the photosensitive member. FIG. 6 shows a conventional example disclosed in Japanese Unexamined Patent Publication No. 58-6391e. In FIG. 6, 151 is a photoreceptor, 152 is a developing device, and 153 is a side plate that holds these photoreceptors and the developer. Sealing members 154 and 155 are pasted at positions opposite the ends of the photoreceptor 151. has been done. This sealing member comes into close contact with the photoreceptor 151 to prevent toner from scattering from the developing device 153 toward the end of the photoreceptor 151.

Problems to be Solved by the Invention However, with the configuration of this conventional example, it is difficult to replace the photoreceptor or clean the area around the photoreceptor during maintenance of the apparatus. That is, since the spacer members 154 and 155 remain in pressure contact with the photoreceptor 151 at all times, there is a risk of damaging or staining the photoreceptor when the photoreceptor 151 is inserted or removed.

In view of these points, the present invention provides an image forming apparatus that does not require a complicated configuration, allows easy handling of the photoreceptor during maintenance, and is capable of maintaining high image quality over a long period of time.

Means for Solving the Problems The present invention provides a photoreceptor that rotates while holding an electrostatic image, a plurality of developing means that sequentially forms toner images of a plurality of colors on the photoreceptor, and the photoreceptor. On the other hand, the image forming apparatus has a process means that is separated when the apparatus is stopped and is close to it for at least a certain period of time when the apparatus is in operation, and the process means is provided with a cleaning means for cleaning the end portion of the photoreceptor.

According to the above-described structure, the present invention cleans the end of the photoreceptor when the process means is close to the photoreceptor by using the cleaning means provided in the process means W1 in contact with the photoreceptor to maintain high image quality at all times. In addition to maintaining the image forming apparatus, the process means is separated from the photoreceptor during maintenance, making it easy to insert and remove the photoreceptor and handle it.

Embodiment FIG. 1 is a front view showing the overall configuration of a digital color copying machine to which the present invention is applied. Its configuration and operation will be explained below.

Reference numeral 1 denotes a reading section of a digital color copying machine, which mainly includes a document table 2, a document illumination lamp 3, a lens 4, a color line sensor 5, a drive system 6 for moving these in the sub-scanning direction for scanning, and an image processing circuit ( (not shown).

10 is a writing section of the digital color copying machine.

Reference numeral 11 denotes a Se-based photoreceptor which has increased sensitivity to laser light having a wavelength of 780 to 810 nm, and is rotatably supported in the direction indicated by the arrow. Reference numeral 12 indicates a first charger for charging the surface of the photoreceptor 11 to a predetermined positive potential, and reference numeral 26 indicates a laser beam.

Reference numeral 20 denotes a laser optical section, and the laser beam 26 is emitted from a laser oscillation block 21 and is configured to scan the photoreceptor 11 via a polygon scanner 22, a lens system 23, and mirrors 24 and 25. A part of the scanning light of the laser beam light 26 is reflected by the mirror 27, and the scanning light of the laser beam light 26 is reflected by the starting edge detection sensor 2.
8 is irradiated. There is a developing section 30 on the right side of the photoreceptor 11, and along the periphery of the photoreceptor 11, from the top, there are a Y developer 31 for developing yellow color, an M developer 32 for developing magenta color, and a C developer for developing cyan color. A developing device 33 (hereinafter collectively referred to as a color developing device) and a developing device 34 for developing black color are arranged. The Y developing device 31, the M developing device 32, and the C developing device 33 are non-contact developing devices using non-magnetic one-component toner.
This developing device is capable of developing while flying toner onto the photoreceptor 11 without contacting it. The K developing device 34 is a developing device that uses a two-component developer and performs development while bringing the developer into contact with each other. Each developing device can take two positions, a position close to the photoreceptor 11 and a position away from it, and by rotating the eccentric cams 35 to 38, the Y developing device 31, the M developing device 32, and the C developing device The rear part of the developing device 33 is pushed and moves horizontally to approach the photoreceptor, and the K developing device 34 is pushed by the shaft 39.
The photoreceptor is rotated counterclockwise around the center to be brought close to the photoreceptor and ready for development. FIG. 1 shows a case where only the M developing device 32 is in a developing state.

40 is eccentric cam 35, 36, 37, 38 and current equipment 31
．． This is the motor that drives 32, 33, and 34.

50 is the paper feed section (cassette) 51.52 and manual paper feed section 5
Paper can be fed one by one from each of the cassettes 3, and this figure shows a case where paper 56 is fed from the cassette 51. Paper 56 is fed to the lower surface of photoreceptor 11 via registration rollers 54 .

Reference numeral 60 denotes a transfer conveyance section, in which a semiconductive belt 63 suspended by rollers 61 and 82 is in two states: a state in which a portion of it is lightly pressed against the photoreceptor 11, and a state in which it is separated from the photoreceptor 11. It is also possible to move in the direction of arrow B at the same speed as the outer peripheral surface of the photoreceptor 11. In this figure, photoreceptor 1
1 shows the state of pressure contact. On the other hand, 64 is the second
A charger connects the belt 63 and the photoreceptor 11 via the belt 63.
A high negative potential is applied to the back side of the paper 56 being fed during this period. Reference numeral 65 denotes a cleaning blade for cleaning toner remaining on the belt, and a collection box 66 is disposed below the cleaning blade.

69 is a third charger that sprinkles negative corona when the paper 56 is separated from the belt 63.

Reference numeral 70 denotes a fixing sheet feeding section, in which a heat roller 72 heated by a fixing lamp 71 and a rubber roller 73 are rotatable while being in pressure contact with each other, and paper feeding rollers 74 and 75 are provided at the rear thereof.
A paper tray 78 is also provided.

Reference numeral 80 denotes a cleaner which can assume a two-pronged state in which the fur brush 81 is in light contact with the photoreceptor pair 11 and a state in which it is separated from the photoreceptor 11, and is rotatable in the direction indicated by the arrow. This figure shows a state in which it is in contact with the photoreceptor 11.

Furthermore, a collection roller 82 is rotatably disposed in contact with the fur brush 81, and a negative voltage is applied to the photoreceptor 11 to each of the fur brush 81 and the collection roller 82. A recovery screw 83 is installed at the bottom of the recovery roller 82.
A pipe 84 is connected to the front end of 3, and is connected to a collection box 85 through this pipe 84. cleaner 80
A fourth charger 84 for positively charging the toner on the photoreceptor 11 and a charge eliminating lamp 87 for neutralizing the photoreceptor 11 are disposed at the lower part of the photoreceptor 11 at a position facing the photoreceptor.

Cooling fans 91 and 92 suck air from the lower and upper parts of the writing section 10 and discharge it to the outside of the apparatus.

The above is an overview of the overall configuration of a digital color copying machine to which the present invention is applied.Next, its operation will be explained with a focus on the writing section.

When the original is placed on the document table 2 and the copying operation begins,
A document is read by a reading section 1, and an image to be recorded by a writing section 10 is determined accordingly.

In the writing section, signals to be recorded are input in the order of black, yellow, magenta, and cyan, and recording is performed. First, a black signal is input to the laser oscillation block 21, and the photoreceptor 11 is irradiated with a laser beam 26 modulated according to the black signal.

The photoreceptor 11 rotates in the direction of arrow A while charging the first charger 12.
After being uniformly charged to +850V, the area irradiated with the laser beam 26 according to the signal becomes +50V.
Static electricity is removed to a certain extent. Main scanning of the laser beam light 26 on the photoreceptor 11 is performed by a polygon scanner 22,
Sub-scanning is performed by rotating the photoreceptor 11 in the direction of arrow A, forming a latent image on the photoreceptor. When a latent image is first written on the photoreceptor, the developing unit 30 is set to a black developing state, and only the K developer 34 approaches the photoreceptor 11 by the operation of the eccentric cam 38, while the other developers move away. in a state. Therefore, the latent image corresponding to the black signal formed by the laser beam 26 is developed with black toner by the developing device 34 and passes through other developing devices without being affected. At this time, the timing of contact and separation of the developing device 34 is controlled so that the developing device 34 moves close to the photoreceptor 11 before the exposure starts with the laser beam 2B, and moves away after development. The image developed with black toner reaches the transfer conveyance section 60 as the photoreceptor 11 rotates, but at this time, in the transfer conveyance section 60, the rollers 67 and 88 are at a position slightly rotated clockwise around the axis of the roller 62. , the belt 83 is in a state separated from the surface of the photoreceptor 11, and the image passes through without being disturbed. Furthermore, the fur brush 81 is in a state separated from the photoreceptor 11 at a position slightly rotated counterclockwise around the axis of the recovery screw 83, and here too, the black toner image passes through without being disturbed and returns to the first charger. Pass under 12. The portion of the photoreceptor 11 on which the black toner image is formed is again charged with toner by the first charger 12, and the portion without toner is charged with +8
A portion of the 50V l-ner is also apparently charged to +850V.

The leading edge of the black toner image is recharged and exposed to the laser beam 2 again.
When reaching the irradiation position 6, the laser beam light 26 is modulated according to the yellow signal and is exposed from above the black toner image on the photoreceptor 11. Since the leading edges of the images are aligned and the scanning speed is constant, the black toner image and the latent image based on the yellow signal are formed in positional alignment. Since only the Y developing device 31 of the developing section 30 is close to the photoconductor 11 and the other developing devices are separated, the latent image formed by the yellow signal is developed only with yellow toner and is deposited on the photoconductor. A yellow toner image is formed in addition to a black toner image. At this time, Y developing device 3
1, the timing of contact and separation is controlled so that the photoreceptor 11 approaches the laser beam 26 before exposure starts, and separates after development. Further, since the yellow development is performed in a non-contact manner, the previous black toner image is not disturbed.

Thereafter, recharging is performed in the same manner, and a latent image is formed using a magenta signal.
Magenta development, recharging, latent image formation using a cyan signal, and cyan development are repeated.

At this time, the yellow toner and magenta toner pass through the laser light, so if you expose that part of the photoreceptor as necessary, the static electricity will be removed from that part of the photoconductor, and the magenta and cyan toner will be placed on top of the yellow toner, and the cyan toner will be placed on top of the magenta toner. You can layer toner. After the last cyan toner image is formed, just before the leading edge of the toner image reaches the transfer conveyance section,
The transfer conveyance unit 60 is brought into a state of being lightly pressed against the photoconductor 11, and the paper 56 enters between the photoconductor 11 and the belt 63 by the registration roller 54 at the timing when the leading edge of the toner image and the leading edge of the paper 56 match. It is fed as follows.

While the toner image is transferred onto the paper 56 by the electric field generated by the second charger 64, the paper 56 is conveyed while being attached to the belt 63, but since the curvature of the roller 62 is large, it separates from the belt 63 and is separated from the fixing paper section. Enter. At this time, in order to prevent the toner image on the paper 56 from being disturbed by the separation charge generated on the paper 56 when it is separated from the belt, negative corona is sprinkled from above by a third charger.

When the toner image on the paper 56 passes through the fixing paper section, it is fixed and then stacked on the paper tray. - The untransferred toner image remaining on the photoconductor 11 is positively charged by the fourth charger 86, which starts operating just before the leading edge approaches, and almost simultaneously moves into contact with the photoconductor 11. The electric field applied between the fur brush 81 and the photoreceptor 11 moves the photosensitive material to the fur brush 81 while being rubbed by the fur brush 81 . Furthermore, the toner inside the fur brush 81 is collected by a collection roller 82.
Due to the electric field applied between the fur brush 81 and the fur brush 81, the fur brush moves to the collection roller 82 and is dropped into the collection screw 83 section, and the pipe 8
4 and placed in the collection box.

The surface of the photoreceptor 11 is thereby cleaned, and on the other hand, the charge is removed by the charge removal lamp 87, and the photoreceptor 11 is returned to its initial state and ready for the next copy.

On the other hand, toner that accumulates in small amounts on the belt 63 of the transfer conveyance section 60 due to operational errors or normally is cleaned by a cleaning blade 65 and collected in a collection box 63.
Dropped within 6.

The above is an overview of the overall configuration and operation of a digital color copying machine to which the present invention is applied. Next, the structure and operation of the developing section of this digital color copying machine will be explained in detail.

FIG. 2 is a detailed view of the photoreceptor 11 and developing section 30 in FIG. 1, and this figure shows the M developing device 32 in a developing state.

Each developing unit 31, 32, 33, 34 has a developing unit 41.
This figure shows a part of the developing rack 41 cut away. Reference numeral 101 is a handle for pulling out the developing rack from the main body. Color developer 31.3
2.33 is the second in the free state without applying any external force.
They are biased by a return spring (not shown) installed in the developing rack 41 so as to return to the positions of the Y developing device 31 and the C developing device shown in the figure. Furthermore, when the developing device is supported by a shaft 39 and is not pushed by the eccentric cam 38, it is in a position as shown in FIG. 2 due to its own weight.

Eccentric cams 35, 36, 37, 38 are installed in the main body of the copying machine, and the stored developing device is connected to each leaf spring 44, 45, 4B.
It can be suppressed from the rear via , 47, and approximately 18
By repeating rotation stop every 0 degrees, the developing device can be in a pressed state and a released state.

Next, the method of forming the gap between the photoreceptor and the developing roller of the developing device will be explained with reference to FIG. 3, using the M developing device as a representative. When the M developing device 32 is pushed by the eccentric cam 36 as shown in FIG. A predetermined gap is formed by abutting on. Precisely maintaining this gap is essential to maintaining high image quality. For example, if the gap changes due to scattered toner depositing on this part of the photoreceptor, unevenness will occur in that part during development and the image quality will deteriorate. Adversely affect.

Next, the structure and operation of the cleaner 80 will be explained in detail with reference to FIG. FIG. 4 is a perspective view of the cleaner 80 seen diagonally from the front. The entire cleaner 80 is coaxially supported by a bearing 130 fixed to the main body so as to be rotatable around the recovery screw 83. The fur brush 81 is rotatably supported at both ends by the side wall 131 of the cleaner 80, and further has a spacer roller 1 at the tip of its shaft.
32 are rotatably engaged. The entire cleaner 80 is rotated clockwise around the axis of the bearing 130 by an eccentric cam 88 installed on the main body of the device rotating about 180 degrees around the shaft 89 from the position shown in FIG. The moving fur brush is pressed against the photoreceptor. When pressed, the distance between the fur brush and the photoreceptor is kept constant by a spacer roller 132. The spacer roller 132 is positioned to abut against the end of the photoreceptor 11, similar to the spacer roller 122 of the developing device shown in FIG. 3, with respect to the photoreceptor. Further, a seal 133 is provided on a portion of the side wall 131 facing the photoreceptor to stop toner from scattering outward from the fur brush 81, and a spacer roller 12 is provided at the end of the photoreceptor.
2 (FIG. 3), a blade 134 is installed to clean the area where the blades 132 come into contact. The seal 133 is made of an elastic material such as sponge or felt, and the blade 134 is made of a sheet of resin such as polyethylene terephthalate or a rubber material such as polyurethane. are pressed against the end of the photoreceptor, and when the fur brush 81 is separated from the photoreceptor, these are also separated from the photoreceptor. Due to these configurations, the cleaner 80 is normally separated from the photoreceptor and comes into pressure contact with the end of the photoreceptor to perform cleaning only when the cleaner 80 operates to clean the toner on the photoreceptor.

The above is an explanation of the configuration and operation of one embodiment of the present invention.
As mentioned above, the gap accuracy between the photoreceptor and the developing roller is maintained with a simple configuration by installing a blade that cleans the edge of the photoreceptor in the cleaner that is normally separated from the photoreceptor and comes into contact with the photoreceptor only when necessary. It is possible to maintain high image quality at all times. Further, when the apparatus is stopped, this blade is separated from the photoreceptor together with the cleaner, so maintenance such as replacement of the photoreceptor can be easily performed. Furthermore, since the blade is usually separated from the photoreceptor, its elasticity and surface change less with time and can maintain stable operation over a long period of time.

Next, FIG. 5 shows another embodiment of the present invention. This embodiment has the same structure as the first embodiment except for the cleaner and the transfer conveyance section. FIG. 5 is a perspective view of a part of the transfer conveyance section 60 of this embodiment, viewed diagonally from the front. A spacer roller 142 is rotatably supported on the upper part of a side plate 141 that supports rollers 68, 61, etc. on which a belt 63 is suspended, and a blade 143 is installed near the spacer roller 142.

The blade 143 is made of the same resin sheet or rubber material as in the first embodiment. The entire conveying section is pushed up by a cam (not shown) installed below only when the toner image on the photoconductor is transferred to paper, and the photoconductor is exposed until the spacer roller 142 comes into contact with the end of the photoconductor. Close to the body. At this time, the belt 63 comes into contact with the photoreceptor to enable transfer, and the tip of the blade 143 comes into pressure contact with the end of the photoreceptor to clean this area. In this embodiment as well, the same effect as in the first embodiment can be obtained by installing the blade in the transfer conveyance section close to the photoreceptor only when necessary.

As described in detail, the present invention provides an excellent color image forming apparatus that can maintain high image quality over a long period of time without requiring a complicated configuration, and that is easy to maintain such as replacing photoreceptors. This is what we provide.

[Brief explanation of the drawing]

FIG. 1 is a side view of a digital color copying machine which is an embodiment of the present invention, FIG. 2 is a side view showing details of its developing section, and FIG. 3 is a top view of the M developing device shown in FIG. 4 is a perspective view of a part of the cleaner of the first embodiment, and FIG. 5 is a perspective view of a part of the cleaner of the first embodiment.
FIG. 6 is a perspective view of a part of the transfer conveyance section of the embodiment, and FIG. 6 is a diagram showing the developing section of the conventional example. 1...Reading section, 2...Writing section, 1.1...
・Photoreceptor, 30...Developing section, 31...Y developing device, 3
2...M developer, 33...C developer, 34...K
Developing device, 35-38... Eccentric cam, 88... Eccentric cam, 132... Spacer roller, 134... Play 1', 142... Spacer roller, 143...
blade. Name of agent: Patent attorney Shigetaka Awano (1 person) 34

Claims (4)

[Claims] (1) A photoconductor that rotates while holding an electrostatic image, a plurality of developing means that sequentially form toner images of a plurality of colors on the photoconductor, and a distance from the photoconductor when the device is stopped. 1. A color image forming apparatus, wherein the color image forming apparatus has a processing means that is close to the image forming apparatus for at least a certain period of time during operation, and the processing means is provided with a cleaning means for cleaning an end portion of the photoreceptor. (2) The color image forming apparatus according to claim 1, wherein at least one of the plurality of developing means is a developing means that performs development without contacting the photoreceptor. (3) The color image forming apparatus according to claim 1 or 2, wherein the process means is a cleaner that approaches the photoreceptor and cleans the toner on the photoreceptor only when necessary. (4) Claim 1 or 2, wherein the process means is a transfer means that approaches the photoreceptor and transfers the image onto the recording paper only when necessary.
The color image forming apparatus described above.