JPS63284577A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a device of high reliability and a copy of high image quality without complicating the constitution of a driving system for many developing devices by using thee driving system whose members are engaged with or disengaged from one another in accordance with development states of plural developing devices. CONSTITUTION:A photosensitive body 11 is rotated through gears 114, 115, and 112 by a driving source 113, and a gear 116 axially supported on its fixed shaft 111 is rotated through a gear 130 by a developing driving source 131. The driving force of the gear 116 is transmitted to a buffer gear 117 and a developing gear 118. When an M developing device 32 is in the development state to be close to the photosensitive body 11, a development roll gear 119 and a development gear 118 are engaged with each other. Development roll gears 133, 134, and 135 of the other developing devices are disengaged from development gears 136 and 137. The gear 134 of a C developing device and the gear 135 of a K developing device are engaged with or disengaged from the gear 137.

Description

DETAILED DESCRIPTION OF THE INVENTION Page 2 Field of Industrial Application The present invention relates to a drive system for a developing device in an image forming apparatus such as a copying machine or a printer to which electrophotography is applied.

2. Description of the Related Art Conventionally, two types of drive systems for driving developing units of image forming apparatuses such as copying machines have been proposed. One type drives the developing device independently, and the other uses a drive source that rotationally drives the photoreceptor and derives its drive from a gear provided on the photoreceptor. FIG. 5 shows the former conventional example, and FIG. 6 shows the latter conventional example. The configuration and operation of these conventional examples will be explained below.

In FIG. 5, a photoreceptor 231 is rotationally driven in the direction of the arrow by a drive system (not shown).

On the other hand, 232 is a developing device disposed adjacent to the photoreceptor 231, and is driven via a gear system 234 by a transmission means 233 such as a belt or chain. Reference numerals 235 and 236 denote a clutch and a three-page solenoid for transmitting or disengaging the driving force of the transmitting means 233 to the developing device.

FIG. 6 shows a drive system of a developing device proposed in Japanese Patent Laid-Open No. 57-136670. In this figure, parts that have the same role as in FIG. 5 are indicated by the same numbers. In the configuration shown in this figure, the developing device 282 is driven by a gear provided on the photoreceptor.

Problems to be Solved by the Invention The drive system of the conventional developing device as described above has the following problems. That is, in the example shown in FIG. 5, one drive system or a control system for intermittent driving force is required for one developing device, making the device complex and having low reliability. This becomes a decisive problem especially when a plurality of developing sections are switched and driven as in the case where the present invention is applied. Furthermore, the structure is such that image quality is likely to be adversely affected by the shock of load fluctuations applied to the developing device 232 and the drive source when the clutch 235 is switched. In addition, in the example shown in FIG. 6, the driving force for the developing device is taken from the photoreceptor, so if there are multiple developing devices and it is necessary to switch their drive as in the case of the present invention, the load fluctuation at the time of switching will be This adversely affects the rotation accuracy of the photoreceptor, and the shock of load fluctuations on the drive source is even greater, resulting in unavoidable deterioration in copy image quality such as jitter and positional deviation.

Means for Solving the Problems The present invention provides an electrostatic image carrier that rotates while holding an electrostatic image, a plurality of developing means disposed around the electrostatic image carrier, and the plurality of developing means. a development selection means for selecting a development state and a non-development state, and a development drive means that is coupled to the development means in the development state and separated in the non-development state;
Further, in the image forming apparatus, the development driving means includes a driving force buffering means.

action The effects of the above means are as follows.

In other words, the driving of a plurality of developing devices arranged around the electrostatic image carrier is switched by connecting or separating the driving system depending on the developing state or non-developing state of the developing device, so it is difficult to drive a large number of developing devices. The developing device drive system is simplified without requiring a complicated drive system, and since the drive system shown on page 5 has a drive force buffer means, load fluctuations caused by shocks during engagement and separation can be avoided by the drive source or the drive system. It is possible to provide a high-quality image forming apparatus in which the electrostatic charge is not transmitted to the electrostatic image carrier, has little jitter, and in particular, in color image forming apparatuses, has accurate mutual alignment of each color.

Embodiment FIG. 1 is a front view showing the overall structure of a digital color copying machine to which the present invention is applied.The structure and operation thereof 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 in this figure).

10 is a writing section of the digital color copying machine. 1
Reference numeral 1 denotes a Se-based photoreceptor that has increased sensitivity to laser light having a wavelength of 780 to 810 nm, and is rotatably supported in the direction of arrow A. 12 is a 6-page first charger for charging the surface of the photoreceptor 11 to a predetermined positive potential, and 26 is a laser beam light. 20 is a laser optical section, and a laser beam 26 is a laser oscillation block 2.
1, a polygon scanner 22, a lens system 23
, mirrors 24 and 25 to scan the photoreceptor 11. A part of the scanning light of the laser beam light 26 is reflected by the mirror 27 and is irradiated onto the starting edge detection sensor 28 . A developing section 30 is located on the right side of the photoreceptor 11.
A Y developing device 31 for developing yellow color, an M developing device 32 for developing magenta color, a C developing device 33 for developing cyan color, and a developing device 34 for developing black color are arranged in order from the top along the circumference of 1. has been done. Each developer can take two positions, a position close to the photoreceptor 11 and a position separated from it,
By rotating the eccentric cams 35 to 38, Y
The developing device 31, M developing device 32, and C developing device 33 are located at the rear thereof,
The bottom of the K developing device is pressed to bring it close to the photoreceptor so that it can develop. FIG. 1 shows a case where only the M developing device 32 is in a developing state.

Reference numeral 50 denotes a paper feed unit that can feed sheets one by one from each of the cassettes 51 and 52 and the manual 7-page paper feed unit 53. In this figure, the case where the paper 56 is fed from the cassette 51 is shown. It shows. The paper 56 has registration rollers 54.5
5 and is fed to the lower surface of the photoreceptor 11. Reference numeral 60 denotes a transfer conveyance section, in which a semiconductive belt 63 suspended between rollers 61 and 62 can be in two states: a state in which a portion thereof 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, the state where it is separated from the photoreceptor 11 is shown. On the other hand, 64 is a second charger for transfer, which applies a negative high potential to the back surface of the paper 56 that is fed between the belt 63 and the photoreceptor 11 via the belt 63. 65
1 is a cleaning blade for cleaning toner remaining on the belt, and a collection screw 66 is disposed below the cleaning blade. 67 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 ejecting section, in which a heat roller 71 heated by a fixing lamp 71 and a bum roller 78 are rotatable while being in pressure contact with each other, and a sheet ejecting roller 74 is provided at the rear thereof.
．． 75 and a paper discharge tray 76 are provided.

80 is a cleaner static eliminator, and a fur brush 81 is connected to the photoreceptor 11.
It is possible to take two states, a state in which it is lightly in contact with the photoreceptor 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 separated from the photoreceptor 11. Further, a collecting roller 82 is rotatably disposed while contacting the fur brush 81.
1. A negative voltage is applied to each collection roller 82 with respect to the photoreceptor 11. A collection screw 83 is installed at the bottom of the collection roller 82, and a vibrator 84 is connected to the front end of the collection screw 83, and is connected to a collection box 85 through this. The pipe 84 is also connected to the front end of the collection screw 66 of the transfer conveyance section 60 in the middle, and the collection box 85
guided by. These connecting parts are omitted in this figure.

A fourth charger 85 for positively charging the toner on the photoreceptor 11 and a static elimination lamp 86 for neutralizing the photoreceptor 11 are located at the bottom of the fur brush 81 and the like, facing the photoreceptor 9 pages. It is located.

Cooling fans 101 and 102 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, and its operation will now be described.

When a document is placed on the document table 2 and the copy button is pressed, the document illumination lamp 3 is turned on and an image of the document is projected in a line onto the color line sensor 5. While being electrically scanned repeatedly at high speed in the depth direction), the drive system 6 scans the sub-scanning direction (
(to the right on the page). The color line sensor 5 outputs R, G, and B color signals at the same time, and the main scanning and sub-scanning described above cause the R%G and B signals to correspond to each point on the document. It is input to the image processing circuit in a temporal series.

10 pages The image processing circuit processes R and G corresponding to each point on the document.

From the B signal, signals for each color of yellow, magenta, cyan, and black to be developed are calculated and output for each point. In color copying, the document is sub-scanned by the reading unit 1 four times for one copy, and in the first sub-scanning, a yellow signal output from the image processing circuit is input to the laser transmission block 21 and is sent onto the photoreceptor 11. is irradiated with a laser beam 26 modulated according to the yellow signal.

The photoreceptor 11 rotates in the direction of arrow A while charging the first charger 12.
After being uniformly charged to +850V, the portion irradiated with the laser beam 26 is neutralized to a minimum of about +50V depending on the intensity of the laser beam 26. Laser beam light 26 on photoreceptor 11
Main scanning is performed by the polygon scanner 22, and sub-scanning is performed by rotating the photoreceptor 11 in the direction of the arrow, but the repetition timing of this main scanning is made to correspond to the main scanning repetition timing of the color line sensor 5, Since the circumferential speed of the photoreceptor 11 and the moving speed of the color line sensor 5 in the sub-scanning direction are made to correspond, the laser beam is simultaneously applied to each point of the document according to the yellow signal while reading the original 11-page document. Light 26 is irradiated onto the photoreceptor 11 to form a latent image of the original.

During the first sub-scanning of the reading section 1, the developing section 30 is set to a yellow developing state, and only the Y developing device 31 approaches the photoreceptor 11 by the operation of the eccentric cam 35, while the other developing devices move away. in a state.

Therefore, the latent image corresponding to the yellow signal formed by the laser beam 26 is developed with yellow toner by the Y developing device 31 and passes through other developing devices without being affected. The image developed with yellow 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 68 are rotated slightly counterclockwise around the axis of the roller 61. The belt 63 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 yellow 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 yellow toner image was formed is again
The toner is recharged by the charger 12, and the area without toner is +850■, and the area with toner is also apparently +8
It is charged to 50V.

When the leading edge of the yellow toner image is recharged and comes to the irradiation position of the laser beam 26 again, the driving system 6 is controlled so that the color line sensor 5 in the reading section 11 starts scanning from the starting edge of the document again. The second scan of the reading unit 1 involves image processing lol! A magenta signal is input from 7 to the laser transmission block, and a laser beam 26 is modulated according to the magenta signal and is exposed from above the yellow toner image on the photoreceptor 11. Since the leading edges of the images are aligned and the scanning speed is constant, the yellow toner image and the latent image formed by the magenta signal are formed in positional alignment. Since only the M developing device 32 of the developing section 30 is close to the photoconductor 11 and the other developing devices are separated, the latent image formed by the magenta signal is developed only with magenta toner, and the yellow toner image is developed with magenta. Thirteen toner images are superimposed.

Thereafter, recharging, latent image formation using a cyan signal, cyan development, recharging, latent image formation using a black signal, and black development are repeated in the same manner. After the last black toner image is formed, just before the leading edge of the toner image reaches the transfer conveying unit 60, the transfer conveying unit 60 is brought into light pressure contact with the photoreceptor 11, and the leading edge of the toner image and the paper 56 are brought into contact with each other. The paper 56 is moved to the photoreceptor 1 by the registration rollers 54 and 55 at the timing when the leading edge matches the paper 56.
1 and the belt 63.

While the toner image is transferred to 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 discharge section. Enter. At this time, in order to prevent the toner image on the paper 56 from being disturbed by peeling charge generated on the paper 56 when it is separated from the belt, negative corona is sprinkled from above by a third charger. The toner image on the paper 56 is fixed when passing through the fixing/discharging section and then stacked on the paper discharging tray.

Ji
Page 14 - Force The untransferred toner remaining on the photoreceptor 11 is positively charged by the fourth charger which starts operating immediately before the tip thereof, and almost simultaneously comes into contact with the photoreceptor 11. While being rubbed by the moved fur brush 81, it is transferred to the fur brush 81 due to the electric field applied between the fur brush 81 and the photoreceptor 11. Further, the toner in the fur brush 81 is transferred to the collection roller 82 by the electric field applied between the collection roller 82 and the fur brush 81, is dropped into the collection screw 83, and is stored in the collection box through the pipe 84. The surface of the photoreceptor 11 is thereby cleaned, and on the other hand, the charge is removed by the charge removal lamp 86, and the photoreceptor 11 is returned to its initial state and ready for the next copy.

On the other hand, toner that accumulates slightly on the belt 63 of the transfer conveyance section 6''0 due to operational errors is cleaned by the cleaning blade 65 and removed by the collection screw 6.
Dropped into part 6 and passed through pipe 84 to collection box "85"
stored within.

The above is an overview of the overall configuration and operation of a 15-page digital color copying machine to which the present invention is applied. Next, the configuration and operation of the drive system of the developing section 30 of this digital color copying machine will be explained in detail.

FIG. 2 is a plan view of the photoreceptor 11, M developing unit 32, and part of their drive system in FIG. 1, viewed from above.

In FIG. 2, the photoreceptor 11 is rotatably supported around a fixed shaft 111, and a gear 11 is attached to the side end of the photoreceptor 11.
2 are integrally fixed. The photoreceptor 11 is rotationally driven by a photoreceptor drive source 113 through gears 114 , 115 , and 112 .

On the other hand, a center gear 116 is rotatably supported on the fixed shaft 111, and is connected to the developing drive source 13 through a gear 130.
1 is rotationally driven. A buffer gear 117 is further connected to the center gear 116, and the driving force is transmitted to a developing gear 118 coaxially connected to the buffer gear 117 via a driving force buffer. Regarding this driving force v1 force, a developing roller gear 119 is integrally fixed to the end of the shaft of the developing roller 120 of the 0M developing device 32, which will be described later, and as shown in FIG. In the developing state close to the body, the developing roller gear 119 and the developing gear 118 are set in a positional relationship in which they are in a connected state. A spacer roller 132 is rotatably supported on the shaft of the developing roller 120. The spacer roller 132 is set to have a diameter 300 μm larger than that of the developing roller 120, and is connected to the developing roller 120 and the photosensitive member when the M developing device 32 is in the developing state close to the photosensitive member 11. This is to set the distance between the bodies 11 to a constant 150 μm.

FIG. 3 shows the developing drive system seen in the direction of the arrow F-F' in FIG. 2, with only the M developing device 32 in a state close to the photoreceptor 11, and the developing roller gear 119 and the developing gear 118 in a connected state. Yes, developing roller gears 133 and 134 of other developing devices
．． 135 shows a state in which it is separated from the developing gears 136 and 137. As the center gear 116 rotates in the direction of arrow G, the developing roller gear 119 rotates in the direction of arrow H. Here, as shown in FIG. 1, the developing device 34 is constructed so that when its bottom is pressed and released by an eccentric cam 38, its leading end 17 pages can be moved up and down between a developing state and a non-developing state. Therefore, the developing roller gear 184 of the C developing device and the developing roller gear 135 of the developing device are connected to the same developing gear 137.
They are now spaced apart.

Next, the driving force buffer section incorporated between the buffer gear 117 and the developing gear 118 will be explained with reference to FIG.

FIG. 4(b) shows the buffer gear 117 and the developing gear 1 in FIG.
A cross-sectional view of part 18 viewed from the same direction as Figure 2 (a)
is a view of this from above. The buffer gear 117 and the developing gear 118 are rotatably supported on a common shaft 138, and are mutually biased by springs 141 whose ends are engaged with respective pins 139 and 140 implanted therein. .

The biasing torque of the spring 141 is set to a value that is sufficiently weaker than the load torque caused by the developing device. Developing gear 1 in non-developing state
When no load is applied to the gear 18, the bottle 140 is engaged with one end of the elongated hole 142 of the buffer gear 117, as shown in FIG. rotating in the direction. When the M developing unit 32 is brought into the developing state and a load is applied to the 18th page developing gear 118, the load fluctuation is not directly transmitted to the gear at first, but the spring 141 is bent to absorb the shock when the load is applied. When the load on the developing device continues to be applied, the spring 141 is set to be weaker than the torque due to the load, so the bottle 140 is locked to the other end of the long hole of the buffer gear 117, and the buffer gear 117 and the developing gear are again connected to each other. 11
8 rotates integrally.

As described above, in this embodiment, the developing device is driven by a drive system that engages and separates depending on whether the developing device is in the developing state or in the non-developing state. A highly reliable device can be obtained without complicating the configuration. Moreover, the shock caused by the load fluctuation that occurs when switching the developing device is applied to the buffer gear 117 and the developing gear 118.
Because it is absorbed between the two and is not directly transmitted to the driving source,
You can obtain high-quality copies without jitter or image misalignment. In this embodiment, an embodiment in which the driving force ia leveling means is included in the developing driving means has been described, but it goes without saying that the same applies when the driving force ia leveling means is included in the developing means as shown on page 19. That is, the driving force buffer explained in FIG.
A similar effect can be obtained when it is incorporated into the 119.134.135 portion.

Effects of the Invention As described above, according to the present invention, a drive system for operating a large number of developing units can be realized with a simple configuration, and a high-performance drive system that is not adversely affected by the shock of load fluctuation when switching between developing units can be realized. The purpose of the present invention is to provide an image forming apparatus that can produce highly reliable and high-quality copies because of its driving capability.

[Brief explanation of drawings]

FIG. 1 is a principle diagram showing the overall configuration of a digital color copying machine to which the present invention is applied, FIG. 2 is a side view of a drive system of an image forming apparatus in an embodiment of the present invention, and FIG. 3 is a front view thereof. FIG. 4 is a detailed view for explaining a buffer section provided between gears of the apparatus, and FIGS. 5 and 6 are perspective views of main parts of a conventional image forming apparatus. 1...Reading section, 2...Writing section, 11...
Photoreceptor, 30...Developing section, 31...Y developing device, 32
...M developer, 33...C developer, 34...K developer, 35-38... eccentric cam, 116... center gear, 117... buffer gear, 118... developing gear,
119...Developing roller gear, 141...Name of spring agent Patent attorney Toshio Nakao One idiot Figure 4 Figure 3 Figure 13 B

Claims (3)

[Claims] (1) an electrostatic image holder that rotates while holding an electrostatic image; a plurality of developing means provided opposite the electrostatic image holder;
a development selection means for selecting the plurality of development means respectively between a development state and a non-development state; and a development drive means that is coupled to the development means in the development state and separated in the non-development state, and the development drive means Or an image forming apparatus in which the developing means has a driving force buffering means. (2) The image forming apparatus according to claim 1, wherein the development selecting means includes a separating means for bringing the developing means close to the electrostatic image holder in a developing state and separating it in a non-developing state. (3) The image forming apparatus according to claim 1 or 2, wherein the driving force buffer means comprises two coaxial gears engaged via a spring.