JPS61208063A - Color image forming device - Google Patents

Abstract

PURPOSE:To reduce the ratio of occupied space by a developing device and to make a photosensitive body and a rotational developing device into units by moving a magnet enveloped by the developer supporting member of the developing device to the 2nd position from the 1st one and varying the position of the magnet at the time of developing from that non-developing. CONSTITUTION:A potential measuring sensor decides a developer bias voltage value corresponding to the color with the aid of a surface potential on the photosensitive body 14 being an image carrier, and transmits it to a fixed electrode at the developing position. The revolution of the rotational developing device 17 moves the developing device 171 in the direction of an arrow, and the magnet 46 is held at the non- developing until the bias voltage of the color is applied to the developer supporting member 45. Then, when the developing device 171 reaches the developing position on which the bias voltage is impressed as the revolution advances, a magnet fixing shift drive motor 56 is driven to rotate a magnet fixing shaft 53, and a main magnet N in the magnet 46 is caused to face the photosensitive body 14. And the position of the magnet 46 at the time of develop in is different from that at non-developing, and accordingly the ratio of the space occupied by the developing devices 171-174 of a color image forming device is reduced.

Description

[Detailed Description of the Invention] [Scope of Industrial Application] The present invention relates to an image forming apparatus using a multi-color developing device, and can be applied to a % verification device or a one-scythe device. Conventional devices of this kind, which develop electrostatic latent images of each color formed on a photoreceptor using each color signal obtained by the photoreceptor, develop a plurality of developer materials of each color in close proximity to the circumference of the photoreceptor. It had a configuration in which the current mine head was installed side by side.

In this configuration, (1) the developing device occupies a large proportion of the inside of the apparatus; (2) the apparatus becomes large in size and expensive;

■ In other words, it is not possible to use a downsized photoreceptor.

(2) For each color, the distance between the position where the electrostatic latent is formed and the development position is different, causing a change in the temporal attenuation of the electrostatic charge agI, and it is necessary to correct this by some means.

It had the following drawbacks.

Therefore, we have proposed a structure in which multiple developing devices are divided and positioned on the circumference around the rotation axis, and when developing in the required color, the rotating developing devices revolve and the developing devices are closed every week. has been done.

[Problem that the invention seeks to solve]

In this configuration, compared to the above-described combined developing device (11), the ratio of the developing device within the device is small, so that the device can be made smaller and less expensive.

(Ill) It is possible to use a downsized photoreceptor, and it is also possible to combine the photoreceptor and the rotary developing device into a unit.

(Button) Since the distance between the position where an electrostatic latent image is formed for each color and the development position is always constant, there is no need to correct changes in the decay of the electrostatic latent image over time.

For example, when a two-component developer is used and the development position is opposite to the surface of the electrostatic latent image support, a fixed electrode is placed at the end of the developer support member to meet the characteristics of the developer. 9. Applying a developing bias voltage. This is because if a slip ring shape is used that matches the trajectory of the circular motion of the developer support member instead of a fixed electrode, the rounding mechanism that always applies the developing bias voltage to the end of the developer support member becomes complicated. At the same time, prices will continue to rise.

■ Since other developing devices that do not contribute to development revolve while constantly applying a developing bias, they become a source of noise to the electrical system of the main body of the machine and may cause malfunctions.

(2) This is because the developing bias voltage is also applied to the developing device in which the developer layer is exposed, which is dangerous.

However, when an electrostatic latent image is developed by contact while applying a developing bias voltage to the fixed electrode as described above, the following problems occur.

Generally, an electrostatic latent image is developed by attaching toner charged to a polarity opposite to that of the image area to the electrostatic latent image. In this case, there is a tendency for so-called capri development in which some toner adheres to non-image areas, so WJ
gI! It is necessary to prevent this for quality reasons. As a measure to prevent so-called capri development in magnetic brush development, an appropriate development bias voltage having a polarity opposite to that of the toner is applied to the magnetic brush.

In the case of a rotary developing device, as mentioned above, so-called Capri development does not pose any problem if an appropriate developing bias voltage is applied during percent development, but if the rotary developing device revolves before and after development. K causes the following problems.

(al) Occurrence of so-called Capri development before contact development with the surface of the electrostatic latent image support.

That is, in a state in which spikes of the developer layer are formed on the developer support member, as the rotary developing device revolves, 1 is generated in a short period of time until it reaches the development position facing the surface of the electrostatic latent image support member. The spikes of the developer layer are in contact with the surface of the electrostatic latent image support, and the end of the developer support member does not reach the development bias voltage supply fixed electrode located at the development position, and the developer layer K i If my bias voltage is not transmitted, '#< will occur.

(1) 1. Occurrence of so-called capri development when separation from the development position is started after completion of contact development.

That is, after the development is completed at the development position facing the surface of the electrostatic latent image support, the developer layer begins to leave the development position due to the revolution of the rotary developing device with spikes of the developer layer formed on the developer support member. In the FRP button, the spikes of the developer layer are still in contact with the surface of the electrostatic latent image support, and the fixed voltage for supplying the bias voltage and the terminal end of the developer support member are separated, and the developing This occurs when a developing bias voltage is not transmitted to the agent layer.

(Occurrence of so-called Capri development when a development device that does not contribute to zero development simply passes through the development position facing the electrostatic temperature compensation support.

That is, when a developing bias voltage commensurate with the amount of developer in the developing device passing through is applied to the fixed electrode for supplying developing bias, capri development is performed as described above (!L value).

In addition, when a developing bias voltage commensurate with the developer in the developing device passing through is not applied to the fixed electrode for supplying developing bias, capri development at the developing position is added as described above (at (b)). The degree of capri development is
There is a close relationship between the surface potential of the photoreceptor, the potential difference with the toner, and whether or not the developer supporting member is grounded. It seems to have the least Capri development.

The following items are listed as the adverse effects of this Capri development.

(11 Dirty transfer drum.

(II) Dirty transfer corona.

([111 The front and rear ends of the surface of the transfer material are dirty.

(IV) Dirt on the back side of the transfer material.

In addition, as a problem other than the above-mentioned Capri development, when the developer on the developer support member formed in the magnetic field υ of the main development pole moves to the development position facing the rotating photoreceptor, 1 Since the spiked portion of the developer is mechanically compressed to form the developing area necessary for contact development of the electrostatic latent image formed on the photoreceptor, the inevitable 1ull is disturbed. , scattering of the agent and toner is likely to occur.

In addition, there is a risk that the surface of the photoreceptor may be damaged due to mechanical collision between the developer and the surface of the photoreceptor.

[Purpose of the invention]

In view of these points, the present invention eliminates the above-mentioned defects such as stains on the transfer drum, transfer corona, and stains on the transfer material.
It is also possible to remove internal contamination caused by toner and developer scattering, which is stored in the developing sleeve and is generated when the rotary developing device revolves and stops.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. Third
The figure is a cross-sectional view of a color image forming apparatus to which a rotary developing device according to the present invention is applied, in which 1 is a copying machine body, 2 is a document table, and 3
is the original, 4 is the light source lamp 5, 6.7 is the movable mirror, 8 is the lens, 9 is the fixed mirror, 10 is the color separation filter, 1
1 is a dust-proof glass, 12 is an exposure part 15 is II & light body fixing axis, 14 is a photoreceptor having a photosensitive layer and serves as an electrostatic latent scratch support, 15 is a primary charger, 16 is a surface potential measurement sensor 1
7 is a rotary developing device 171 having a yellow developer, 172 is a magenta developing device having a magenta developer, 173 is a cyan developing device having a cyan developer, 174 is a black developing device having a black developer, and 18 is a rotary developing device having a yellow developer. Transfer drum using screen mesh, 19
20 is a cleaner pre-charger, 20 is a cleaning device 21, a gripper 22 is a gripper cam, 23 is an adsorption charger, 2
4 is the presser roller, 25 is the transfer corona%, 26 is the gripper
cam, 27 is a separation claw 28 is a static eliminator, 29 is a static eliminator, 30 is a cassette 31 is a transfer material, 32 is a pickup roller, 55, 54.35 is a conveyance guide 56, 37 is a transfer material conveyance roller, 58 is a Grip position, 39 is a conveyance belt, 40 is a conveyance guide, 41.42 is a pair of fixing rollers, and 43 is a tray.

Next, in the above configuration, the photoreceptor 14 supported by the shaft 13 starts rotating in the direction of the arrow in response to a copy command, and its surface is uniformly charged by the negative charger 15. Next, when the original 3 on the original platen 2 placed on the top surface of the copying machine body 1 is irradiated with the light source lamp 4, the optical path length from the original s3 to the lens 8 is constant. As shown in FIG.
The light passes through a moving exposure optical system consisting of a color separation filter 101C, passes through a color separation filter 101C, and is exposed onto a photoreceptor 14 at an exposure unit 12 via a dustproof glass 11.

Here, when a blue filter is selected as the color separation filter 10, an electrostatic latent image of a yellow image is formed on the photoreceptor 14, and this is developed as a yellow image by the yellow developing device 171. Ru. After developing the yellow image, the rotary developing device [17] rotates in the direction of the arrow to move the magenta developing device 172 to the developing position RK, and the magenta latent image is formed on the photoreceptor 14 by the next green filter. By forming the image and developing it with a magenta developing device [172], it can be realized as a magenta image. The cyan image is similarly visualized by the red filter.

Further, the transfer material 31 stored in the cassette 30 is ejected and ejected by the rotation of the pickup roller 32 as indicated by the arrow, passes through the conveyor belts 53, 54, 55, and conveyor rollers 36° and 37, and reaches the grip position of the transfer drum 18. 38. The gripper 21 of the transfer drum 18, which rotates as shown by the arrow, opens more than the gripper cam 221C at a grip position 38 and grips the leading end of the transfer material 31. The transfer material 31 is attached to the adsorption charger 2
3. The pressing roller 21C is brought into close contact with the transfer drum 18.

The photoconductor 14 and the transfer drum 18 rotate synchronously, so that the tip of the yellow layer on the photoconductor 14 and the tip of the transfer material 31 on the transfer drum 18 align and abut, and the transfer corona 2
5. Transfer the yellow color to the transfer material 31GC. Next, the magenta image formed on the photoreceptor 14 is transferred onto the yellow image in synchronization with the transfer material holding the previous yellow image.

Thereafter, the desired color image is transferred in this manner a necessary number of times.

After the required number of transfers, the transfer material 31 is transferred to the gripper cam 2.
6, the transfer drum 18 is separated from the transfer drum 18 by the separation claw 27 through the opening of the gripper 21. At this time, the charger 28 prevents the current bond from being disturbed. Conveyor belt 39%
The toner on the transfer material 31 that passes through the conveyance guide 40 and is conveyed by a pair of fixing rollers 41 and 421C rotating in the direction of the arrow is heated and fixed on the transfer material 31.
It is a permanent preservation painting.j5) It is discharged to the tray 43.

After the transfer of each color, the residual potential on the photoreceptor 14 after transfer is removed by a pre-cleaner charger 19, and the remaining toner is cleaned by a cleaning device 20 comprising an elastic blade. Charges remaining on the transfer drum 18 are removed by a charge remover 29.

FIG. 2 is a detailed sectional view of the rotary developing device.

In the figure, reference numeral 17 indicates a rotary developing device 44 for yellow developer, 45 for a developer support member, 46 for a magnet, 47 for a doctor blade, 48 and 49 for replenishing an agitation conveyance screw 50, and yellow toner hopper 51 for replenishing yellow. Toner 52 is a toner supply port. Figure 1(a),'(
b) Fi. Principle diagram of the position of the magnet according to the present invention. FIG. 4 is a perspective view embodying the habitat shown in FIG. 3. In the figure, 53 is a magnet fixed shaft, 54, 55 is a magnet fixed shaft drive gear 56 is a magnet fixed shaft drive motor, 5
Reference numeral 7 designates the current agent support member fixed shaft, 58 and 59 represent the current agent support member fixed shaft drive gears, and 60 company, the current agent support member fixed shaft drive motor.

In the primary configuration, when developing the photoconductor 14 having an electrostatic latent image corresponding to yellow as shown in FIG. A yellow developing bias voltage value is determined based on the potential and is transmitted to a fixed electrode for supplying a developing bias located at a developing position (not shown).

Due to the revolution of the rotary developing device 17] Yellow developing device 171
The magnet 46 maintains the state shown in Figure 1 (a) until it moves in the direction of the arrow and the yellow developing bias voltage is applied to the developing agent support member 45, and as the revolution progresses, the yellow developing bias voltage is applied to the developing agent supporting member 45. Current ranking fin applied: 4th rank only after reaching
The magnet fixed shaft drive motor 56 shown in the figure is driven to rotate the magnet fixed shaft 53 via the magnet fixed shaft drive gears 55 and 54, so that the Nl living space in the magnet faces the photoreceptor 14.

After that, the current agent support member fixed shaft drive motor 60
and drive the current agent support member (6) constant shaft drive gear 5
9.58, the agent support member fixing shaft 57 is rotated in the direction of the arrow in FIG. 2 for a predetermined period of time.

After the development is completed, at the development position WK with the yellow development bias voltage applied, the magnet fixed shaft drive motor 56
and rotate the magnet fixed shaft 53 via the magnet fixed shaft drive gear 55, 54 again as shown in FIG. 1(a).
After the photoconductor 14 and the developer layer 44 are brought into non-contact state, the yellow developing bias voltage is stopped, the rotary developing device 17 is rotated by a drive system (not shown), and the yellow developing device 171 is moved to the developing position. Leave.

Here, the yellow developer 44 is stirred and conveyed from the back to the front by the agitation conveyance screw 4B and from the front to the back by the agitation conveyance screw 49 in FIG. Replenishment toner 51 stored in the hopper 50 is replenished through the toner replenishment port 52.

Furthermore, when a developing device that does not contribute to development simply passes through the developing position facing the photoreceptor 14, not only the developer support member fixed shaft drive motor 60 but also the magnet direction fixed shaft drive motor 56 is not driven. Figure 1 (at
In this state, the rotating developing device #17 revolves to pass through υ.

In this example, a configuration with repulsive magnetic poles at a position facing the agitation conveyance screw 48 is mentioned, and a configuration in which the repulsive magnetic poles are opposed to the photoreceptor as shown in FIG. 1 (at) is used. Without being restricted by the above, it is sufficient to select a range in which the peaks of the developer layer do not come into contact with the photoreceptor by making the electrodes face each other or the electrodes themselves.

Here, Table 1 shows specific experimental values in Figure 1:
The magnetic flux density of each magnetic pole At this time, the distance between the sleeve 45 and the photoreceptor 14 is 2.2
~2.8 Tomomi, preferably 2.6 tm. Also, the distance between the sleeve 45 and the ear cutting blade 47 is 1.6
~2.2 vll, preferably 2. It's Onz. Rotational diffusion of the sleeve at this time 160 to 240 r, p, m
The number of rotations of one magnet is preferably 1 to 2 r, p, m, N, -N, and the height of the spikes between the poles is 1 to 1°5f.
It was about I.

FIG. 5 is a time chart showing the operation timing of each main part at the developing position during development.

As a modification of the above embodiment, the developer may be a one-component developer made of magnetic powder instead of a two-component developer. Further, the support 9 is not limited to a photoreceptor, but may be an insulator, and in this case, an electrostatic recording method is used. Further, image forming apparatuses to which the present invention is applied include, in addition to copying machines, color image forming apparatuses for outputting from electronic computers and receiving output from communication devices.

〔Effect of the invention〕

As explained above, the regular developing bias voltage obtained by potential control in the developing device having the desired color in the rotary developing device is applied to the terminal end of the developer supporting member at the developing position using the fixed electrode. Except when developing while carrying out the development, the magnet contained in the developer support member should be placed in a place where the developer layer has sparse spikes, as shown in Figure 1 (at), so that it does not come into contact with my carrier Therefore, before the developing device having the desired color comes into contact with the compensation carrier during the revolution of the rotary developing device, and after the development is completed,
I was able to completely eliminate capri development when detaching from the carrier. In addition to this, it is now possible to remove toner contamination on the transfer drum and transfer corona, as well as toner contamination on the leading edge, trailing edge, and back surface of the transfer material surface. It has also become possible to eliminate contamination inside the machine due to developer and toner scattering that sometimes occurs.

These improvements have ultimately made it possible to improve the quality of completed images and extend the maintenance and inspection period.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure 1 (al, (bl) is a principle diagram of the position of the magnet according to the present invention, Figure 2 is a sectional view of the rotary developing device according to the present invention, and Figure 3 is a diagram according to the present invention. FIG. 4 is a perspective view embodying the mechanism shown in FIG. 1, and FIG. In the figure, 14 is an image carrier, photoreceptor 17 is a rotary developing device 44, developer 45 is a developer support member 46, magnet 56 is a magnet fixed shaft drive motor 60 is a developer support member Represents a fixed shaft drive motor.

Claims (3)

[Claims] (1) In a color image forming apparatus that forms a latent image according to a color component on an image carrier and develops this latent image by selecting a plurality of color developing devices that move on the same trajectory, the developing device The device has a driving means for moving a magnet contained in a developer support member of the device from a first position to a second position, and the driving means is characterized in that the position of the magnet is different during development and non-development. color image forming device. (2) The driving means adjusts the position of the magnet during non-development to a developing position where the developer layer formed on the developer support member faces the surface of the latent image support. The color image forming apparatus according to claim (1), which is non-contact. (3) The color image forming apparatus according to claim (1), wherein the driving means operates only at a developing position facing the surface of the latent image support.