JPS62262882A - Multicolor developing device - Google Patents

Abstract

PURPOSE:To exactly control the bristle cutting by utilizing rotation control of a sleeve instead of executing the cutting control depending on the mechanical positioning accuracy of a movable member. CONSTITUTION:No magnet is placed in an intermediate area 107Y extending clockwise from a developer catching area 102Y to a developing area 103Y. Accordingly, only a weak magnetic force works onto a sleeve in the intermediate area, and since the sleeve turns toward this feeble magnetic area, a developer is scarcely held. In this case, when the force by which the developer is held on a sleeve 100Y, and also, carried, the frictional force between the sleeve 100Y and the developer, the magnetic suction force of the developer, and the force of gravity for working on the developer are denoted as F, F1, F2 and F3, respectively, there is a relation of F=(F1+F2)-F3. That is to say, there is a relation between a rotating speed of the sleeve and the quantity of the developer held on the sleeve, and when a speed at the time of a reverse rotation is decreased, it can be prevented that the developer is held on the sleeve. In this way, the bristle cutting control can be executed completely.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a multicolor developing device.

(Prior art) n (n≧2) developing rollers each using a developer of a different color are arranged close to the photoreceptor drum, and each latent image on the photoreceptor drum L corresponding to each color is sequentially developed. There is known an image forming apparatus that obtains a color image by transferring and synthesizing the visible images onto a recording medium in the order of development.

In the image forming apparatus described above, when one developing roller is developing, if developer is present on the peripheral surface of each of the other developing rollers, the latent image will be developed in mixed colors.
Regarding the other developing rollers, so-called ear breakage control is performed to ensure that no developer adheres to them.

Conventionally, known means for controlling the panicle breakage include a method of moving a blade toward and away from the surface of the developing roller and a method of moving a magnet inside the developing roller. However, in the former case, it is difficult to completely remove the developer, and in the latter case, it is difficult to ensure positional accuracy when the magnet moves and returns, so that the effect of cutting the ears is incomplete.

Another method is to control the developing roller itself toward and away from the photoreceptor drum, but there are problems such as vibrations caused by the contact and separation leading to abnormal images and difficulty in controlling the gap between the roller and the photoreceptor. be.

(Objective) Therefore, an object of the present invention is to provide a multicolor developing device that can accurately control the cutting of ears.

(Structure) In order to achieve the above object, each developing roller of the present invention is composed of a sleeve that can freely rotate in the forward and reverse directions, and a magnet that is immovably disposed inside the sleeve. When the area in contact with the developer on the source side is defined as the agent collection area, and the area close to and facing the latent image carrier is defined as the development area, ``--between the agent collection area and the above-mentioned development area. The -I- magnet is not arranged inside the sleeve for any one of the two intermediate regions, and the magnet is arranged in the other intermediate region, the agent collecting region, and the developing region. With respect to any one developing roller,
During development, it should be rotated in a direction that advances from the -I- marked sleeve collecting area to -1- marked intermediate area where the magnet is located, and when developing with other developing rollers, it should be rotated at a low speed in the opposite direction to the above. It is characterized by

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

FIG. 1 shows a portion related to a developing device of a color electronic copying machine to which the present invention is applied.

In the figure, reference numeral 2 indicates a photosensitive drum as a latent image carrier, which is rotated counterclockwise as indicated by an arrow 4. As shown in FIG.

=3- Around the photosensitive drum 2, a magenta developing device 6M, a cyan developing device 6C, and a yellow developing device 6Y are arranged for each color of the developer used in the rotational direction of the drum.

For example, if we focus on magenta developing device 916M, case 7
Inside M, a paddle roller 8M, a pumping roller 9M, and a developing roller IOM are arranged in order from bottom to top, and developer is stored in the lower part of the case. and,
The developer is drawn up in the order listed in 1 and supplied to the circumferential surface of the developing roller disposed close to the photosensitive drum 2. Then, it is attached to the peripheral surface of the developing roller by the magnetic force of the magnet provided inside the developing roller.

The remaining developer used for development flows down along the inclined plate 11M which also serves as a scraper.
The water is returned to the paddle roller 8M via an opening (not shown) provided on 1M, via screw conveyors 12M and 13M, or via guide plate 14M.

Since these relationships are exactly the same for the other developing devices, the description of the common members will be omitted by replacing M in the above-mentioned member codes with C2Y.

In such a color electronic copying machine, the photosensitive drum 2
Three different types of color separation filters are arranged around the photoreceptor drum, and a transfer drum (not shown) is elastically pressed against the photoreceptor drum, and these are rotated synchronously at the same circumferential speed.
During the first rotation of the photoreceptor drum, the image light is exposed to the photoreceptor drum through one color separation filter to form a latent image, and this latent image is developed using a developer of a color corresponding to the color separation filter. Developing is performed using a device such as a magenta developing device 6M. Next, this visible image is transferred to a transfer paper held on the outer circumferential surface of the transfer drum using a transfer charger, and each time the photoreceptor drum rotates for the second time, different color separation filters and their corresponding colors, for example, cyan, are transferred. A color image is obtained by forming a visible image using a yellow or yellow developer and superimposing it on the transfer paper for transfer synthesis.

In such a process, while one developing device is developing, other developing devices must be prevented from developing, otherwise the colors will overlap and a desired color image will not be formed.

Therefore, in this example, the sleeve] and 00Y constituting the developing roller IOY are made reversible in the forward and reverse directions. Note that this sleeve 100Y is made of a non-magnetic material. This sleeve 10
When considering orthogonal coordinates with the center of 0Y as the origin, the circumferential surface -
1-. The area corresponding to the boundary between the third and fourth quadrants corresponds to the pumping roller 9Y, and the developer supplied by the rotation of the paddle roller 8Y and the pumping roller 9Y comes into contact with it. ing. This area draws developer.
The area that should be connected from the second roller 9Y to the sleeve 100Y is called the agent collection area, and is denoted by 102Y.
Indicated by

Further, on the circumferential surface of the sleeve 100Y, an area corresponding to the first quadrant is closely opposed to the photoreceptor drum 2, and since the latent image is developed in yellow according to the rotation of the drum 2, it is called the development area. 103Y.

In this way, the agent collecting area 1 is formed on the circumferential surface of the sleeve 100Y.
02Y and the developing area 103■ are determined, the peripheral surface - ] 2. From the agent collecting area 102Y to the developing area 103
The intermediate area up to Y and the agent collection area 1 in the counterclockwise direction.
Two intermediate regions can be considered, an intermediate region from 02Y to development region 103Y.

In this example, magnets are provided inside the sleeve 100Y corresponding to the latter intermediate region, the agent collecting region 102Y, and the developing region 103Y among the two intermediate regions.

This magnet consists of three permanent magnets. Agent collection area 102
The magnet corresponding to Y is indicated by reference numeral 102YG, the magnet corresponding to the middle area of item 1 is indicated by reference numeral 104YG, and the magnet corresponding to development area 03Y is indicated by reference numeral 103YG.

Like the sleeve 100Y, each of the magnets has a length in the direction penetrating the page, and is fixed to an immovable support member 105Y.

On the other hand, in the intermediate region of the former, that is, from the agent collecting region 102Y in a clockwise direction on the circumferential surface, to the developing region 103.
No magnets are provided in the intermediate region up to Y.

As described above, the sleeve 100Y is capable of forward and reverse rotation, and its process consists of forward rotation, reverse rotation, and stopping.

Normal rotation refers to rotation in a counterclockwise direction in which the circumferential surface of the sleeve advances from the agent collection area 102Y to the corresponding intermediate area of the magnet 104YG, and this normal rotation drive occurs when the developing roller IOY is in the developing process. will be done.

The path of the developer during development by the yellow developing device 6Y will be explained with reference to FIG.

The paddle roller 8Y and the pumping roller 9Y are constantly rotating in the direction of the arrow, and supply the developer stored in the lower part of the case 7Y to the agent collection area 102Y.

Note that the pumping roller 9Y is composed of a non-magnetic rotating sleeve having a fixed magnet inside, and supplies the developer to the developing roller IOY using magnetic attraction force.

Under this condition, when the sleeve 100Y rotates forward, the developer is transferred to the sleeve 100Yt by the magnet 1 in the agent collection area 102Y.
It is held by the magnetic attraction force of 02YG and rotates together with the sleeve.

Eventually, the thickness is regulated to a desired thickness by a doctor 106Y provided in the case 7Y, and the yellow 1 in the developer is sent through an intermediate area with a magnet +04YG to a developing area 103Y where a magnet 103YG is located. -Chi=8- adheres to the latent image on the photoreceptor, and visualization is performed.

In such a process, three magnets 102yG.

Due to the arrangement of 104YG, ]03YG, the sleeve 10
The magnetic force effectively acts on the OY, and the developer is distributed and held in the sleeve.

After being subjected to development in this way, the remaining developer is removed from the inclined plate 11.
Send it out on Y. A series of such developer flows is shown in FIG. 2 by broken lines.

When the development is completed, the sleeve 100Y is reversed and shown in a non-development ear cutting process. Therefore, the path of the developer in this ear cutting process will be explained with reference to FIG.

As described above, no magnet is disposed in the intermediate region 107Y extending clockwise from the agent collection region 102Y to the developing region 103Y.

Therefore, only a weak magnetic force acts on the sleeve in the intermediate region, and since the sleeve rotates toward this weak magnetic region, hardly any developer is retained.

Here, the force for holding and transporting the developer in the sleeve 100YI is F, the frictional force between the sleeve 100Y and the developer is Fl, and the magnetic attraction force of the developer is F2, which acts on the developer. If gravity is F3, then F = (Fl + F2)
- There is a relationship called F3.

In other words, there is a relationship between the sleeve rotation speed and the amount of developer retained on the sleeve, and by lowering the speed during reverse rotation, it is possible to prevent developer from being retained on the sleeve.
You can do L. Therefore, this makes the ear breakage control perfect.

The rotational speed of the sleeve 100Y during development is determined by its relationship with the speed of the photoreceptor drum 2, and generally the circumferential speed of the sleeve is set to 2 to 4 times that of the photoreceptor drum 2. In this case, the rotational speed of the sleeve is not particularly restricted, and therefore a low rotational speed can be arbitrarily set in order to increase the ear-cutting effect.

If the reversal amount is one or more rotations before the other developing devices start the developing process, a sufficient ear-cutting effect can be obtained without affecting the finish of the color image.

The sleeve 100Y stops after the above-mentioned reverse rotation. This completes the developing process.

Such a series of developer flows is shown in broken lines in FIG.

As explained above, by specifying the arrangement of the magnets in the sleeve and controlling the rotational direction and rotation speed of the sleeve during development and cutting, a perfect cutting effect can be obtained on the sleeve, and the required amount can be achieved during development. A developer holding state can be obtained.

Moreover, this method does not involve controlling the movement of any of the blades, magnets, developing rollers, etc. as in the prior art, so there is no difficulty in determining the positional accuracy of the members, and the method can be easily controlled by controlling the rotation of the developing sleeve. Moreover, the ear cutting effect can be achieved reliably.

In the above embodiment, the developing roller IOY of the yellow developing device 6Y has been described, but the cyan developing device 6Y has been described.
The above example also applies to the C and magenta developing devices 6M.

Therefore, the components of the developing roller IOC and the developing roller IOH, the arrangement of the magnets, etc. are also 11 in the developing roller IOY.
= Since the configuration conforms to the configuration, the members, etc. related to the developing roller 10C1 and the developing roller 10M will be indicated by replacing M in the reference numerals of the members etc. described for the developing roller 10C with C and M, respectively, and the explanation will be omitted. .

Next, drive control among the developing rollers IOY, IOC, and IOM during one cycle of the color copy process will be explained with reference to FIGS. 5 to 8.

In FIG. 4, the central processing unit receives a drum position signal generated according to the color copying process in the color electronic copying machine, and uses this as an opportunity to send a motor MY normal rotation signal that instructs the developing roller IOY to rotate forward or backward. The reverse rotation signal is output to the motor MY drive device together with the motor MY drive signal.

The motor MY driving device controls the driving of the motor MY according to each of the above input signals.

These relationships are the same for the motor that drives the developing roller IOM and the motor MM that drives the developing roller IOC.

In FIG. 5, which explains the driving relationship between the motors MY, MC, and MM, the developing process (yellow) is performed in the yellow developing device 6Y during the first rotation of the photosensitive drum 2, and the developing process (yellow) is performed in the cyan developing device 6C during the second rotation of the photosensitive drum 2. A developing process (cyan) is executed in the magenta developing device 6M during the third rotation, and a developing process (magenta) is executed in the third rotation.

In the above, it is the drum position signal that commands the start of each developing step, and is issued before the yellow latent image on the photosensitive drum 2 arrives at the yellow developing device 6Y.

At the same time as this first drum position signal is issued, the motor MY forward rotation signal and the motor MY drive signal, which are output from the central processing unit, are simultaneously input to the motor MV drive device, and the Developing roller IOY
rotates forward, making the latent image visible in yellow.

The time during which the motor MY continues to rotate forward is determined by the forward rotation timer T.
Set by ll.

When the yellow development is completed and the set time of the normal rotation timer Tll expires, the delay timer T12 is activated, and during this period, the rotation of the motor MY is stopped. Then, when a short set time of delay timer T]2, which is provided in preparation for shifting to reverse rotation, has elapsed, reversal timer T13 is activated, and during the operating time of this timer, the reversal signal of the motor and the motor MY drive signal are simultaneously transmitted to the motor. Input to MY drive device, motor MY
In response to the reverse rotation of the developer, control for cutting off the developer tip is executed.

At the same time as the motor MY is reversed, the developing roller 10Y may be decelerated by appropriate means, for example, when the motor MY is reversed, power is automatically transmitted through a reduction gear system, or the rotational speed of the motor itself is decelerated by electrical operation. done by, etc.,
The effectiveness of the ear-cutting effect can be achieved.

As described above, the set time of the reverse rotation timer T13 is set to q, which is sufficient time for at least one rotation of the developing roller JOY.

The developing process (yellow) ends when the set time of the reverse rotation timer T13 expires.

While this development] 1 (yellow) is being performed, the rotation of the developing roller IOC and the developing roller 10 is stopped.

Next, when the photosensitive drum 2 enters the second rotation and the cyan latent image arrives at the magenta developing device 6C, a drum position signal for the second rotation is issued, and the process shifts to a developing process (cyan).

In this developing step (cyan), first, the motor MC is driven and the sleeve 100C is rotated in the normal direction, similarly to the developing step (yellow). This forward rotation time is the forward rotation timer T2.
1 is the time when the motor is on, and during this time, a normal rotation signal and a drive signal are given to the motor MY drive device.

In this way, when the development with the cyan developer is completed, the motor stops, and when the operating time of the delay timer T22 ends, the motor rotates in reverse. The reverse rotation is performed while the motor drive signal and the reverse rotation signal are input to the motor MY drive device.

Here, the reverse rotation speed of the sleeve 100C is slower than that during normal rotation development in order to achieve the effect of cutting the ears.

The time for this reversal is determined by the set time of the reversal timer T23, and is given as a time sufficient for at least one revolution of the developing roller 10C.

The developing process (cyan) ends when the set time of the reverse rotation timer T23 expires.

While this developing step (cyan) is being performed, the developing roller 10Y and the developing roller IOM are not rotating.

Next, the photosensitive drum 2 enters its third rotation, and before the magenta latent image reaches the magenta developing device 6, a third drum position signal is issued, and the process shifts to the developing process (magenta).

Also in this developing step (magenta), the developing step (
(cyan), the motor MM is first driven to rotate the sleeve 100M in the normal direction. This forward rotation time is the forward rotation timer T3.
1 is the time when the motor is on, and during this time, a normal rotation signal and a drive signal are given to the motor MM drive device.

In this way, when the development with the magenta developer is completed, the motor MMI stops, and when the operating time of the delay timer T32 ends, it shifts to reverse rotation. The reverse rotation is performed while the drive signal for the motor MM and the reverse rotation signal are input to the motor MM drive device.

Here, the reverse rotation speed of the sleeve 100M is slower than that during normal rotation development in order to achieve the effect of cutting the ears. The time for this reversal is determined by the set time of the reversal timer T33, and is given as a time sufficient for at least one rotation of the developing roller IOM.

The developing process (magenta) ends when the set time of the reverse rotation timer T33 expires.

While this developing step (magenta) is being performed, the developing roller 10Y and the developing roller IOC are not rotating.

The present invention can also be implemented in a multicolor developing device as shown in FIG. In the figure, a yellow developing device 60Y, a cyan developing device 60C, and a magenta developing device 60M are arranged below the photosensitive drum 20.

The yellow developing device 60Y is covered with a case 70Y, and a pumping roller 90Y and a developing roller 15Y are installed in the case 70Y.
There is. The developing roller 15Y is a sleeve 15 that can be rotated forward and backward.
0Y is provided close to the photosensitive drum 2, and magnets 150YG, 152YG, and 154YG are fixed to an immovable member inside thereof.

These relationships are the same in other developing devices.

That is, inside the case 70C of the cyan developing device 60C, there are a pumping roller 90C and a developing roller 15C, and the developing roller 15G has a sleeve 150C and a magnet 150C.
G.

], 52CG, 154CG, etc.

Similarly, inside the case 70M of the magenta developing device 60M, there are a pumping roller 90M and a developing roller 15M.
0M1;.

It consists of 152MG, 154MG, etc.

In this example, each sleeve 150Y, 150C, 1
The arrangement of magnets within 50M is distinctive.

In this example, in each developing device, the magnets in the sleeves are configured so that no magnets are placed in the third quadrant when considering orthogonal coordinates with the center of the sleeve as the origin.

This third quadrant (or fourth quadrant) is the area where the gravity of the developer works most effectively to prevent the developer from being retained in the sleeve, so if a magnet is placed as in this example, the ear breakage effect can be prevented. can be even more effective.

Incidentally, in FIGS. 10 and 11, which illustrate the developer transport path for the yellow developing device, during development, the developer drawn up by the pumping roller 90Y faces the magnet 150YG, as shown in FIG. It is held on the sleeve 150Y in the agent collection area, and the magnet 154MY
The developer is subjected to development in a development area where the developer and photoreceptor drum 20 face each other, and the remaining developer falls below the case 70Y as the sleeve 150Y rotates. Here, the sleeve 150Y is rotated normally in the direction shown by the arrow, and since the magnet 150MG is located in the intermediate region corresponding to the fourth quadrant, its magnetic force effectively contributes to retaining the developer.

On the other hand, during the ear breakage control, as shown in FIG. 11, the sleeve 150Y rotates in the opposite direction, so the sleeve rotates through the intermediate region 1.70Y corresponding to the third quadrant where there is no magnetic force, and the developer is transferred to the sleeve-L. The grains fall without being held by the grains, and therefore a good ear cutting effect can be achieved.

Note that the drive control between the developing rollers 15Y, 15C, and 15M during one cycle of the color copy process =
19= The explanation of FIGS. 4 to 8 above applies to the control.

So far, we have explained the case where no magnet is provided in the third quadrant.
Similar effects can be obtained even when no magnet is provided in the fourth quadrant. However, the direction of rotation of the sleeve, the position of the doctor blade, and the direction of rotation of the pumping roller will naturally be changed.

Next, regarding the surface shape of the developing roller, if implemented in combination with each of the above embodiments, the ability to retain the developer during development can be increased, and when the panicle breakage control is performed, the effect of breaking the panicle can be enhanced. However, I will explain some examples where each effect can be obtained.

In this example, the surface shape of the sleeve constituting the developing roller is formed into a sawtooth shape as shown in FIGS. 12 and 13. Each sawtooth has a configuration in which approximately V-shaped grooves are formed in the axial direction on the circumferential surface of the sleeve at predetermined equal intervals. Among the two slopes forming this V-shape, the surface inclined at an obtuse angle with respect to the tangential direction of the sleeve circumferential surface is called a flank surface 700, and the surface inclined at an acute angle is called a rake surface 710. The angle between the flank surface and a line connecting the light spot P between the flank surface 700 and the circumferential surface and the axis O can be expressed as α.

Similarly, in the plane perpendicular to the axis, the angle between the rake face and a line connecting the light spot Q between the rake face 710 and the circumferential surface and the axis ○ can be expressed as β. In this case, 30″≦α<
90°, so that the values 0″≦β<45° are satisfied,
By determining the angles α and β, the developer can be
The developer retention function is enhanced by scooping it into the letter-shaped groove, and on the other hand, the developer is not retained because it slides on the flank during non-development, making it possible to better control the breakage of the ears.

Of course, the rotation direction of the sleeve during development is the direction in which the circumferential surface portion with the rake surface facing down relative to the flank surface moves upward, as shown by arrow 800 in FIG. 13, and the rotation direction of the sleeve during ear cutting control is is the direction in which the circumferential surface portion with the flank facing down relative to the rake face moves downward, as shown by arrow 810 in the figure.

The sleeve having the circumferential shape of this example is the sleeve 100Y, 100C, 100M or the sleeve 150Y in the above example.
, 150C.

If applied to a 15-inch cylinder, even better ear cutting performance can be obtained due to the synergistic effect with the arrangement of the magnets and the effects of low-speed drive during reverse rotation of the sleeve.

(Effects of the Invention) In the present invention, since the ear cutting control does not depend on the mechanical positioning accuracy of the movable member, but uses rotational control of the sleeve, it is possible to accurately control the ear cutting. It is possible and convenient.

[Brief explanation of drawings]

FIG. 1 is a sectional view of main parts of a multicolor developing device according to the present invention, and FIG.
Figure 3 is a partial diagram showing a part of Figure 1, and Figure 4 explains the signal transmission system of the control system when developing using the multicolor developing device in Figure 1. 5 is a timing chart, FIGS. 6 to 8 are flowcharts of the developing process, FIG. 9 is a sectional view of main parts of a multicolor developing device explaining another embodiment of the present invention, and FIG. 10 , FIG. 11 is a partial explanation of a part of the same figure as above, FIG. 12 is an enlarged view of the surface shape of the sleeve, and FIG. FIG. 3 is a diagram illustrating switching of the ear cut state. 10Y, IOC, IOM, 15Y, 15C, 15
M...Developing roller, 100Y, 100C, 100M
, 150Y, 150C, 150M...sleeve,
102Y, 102C, 102M... agent collection area, 1
．． 03'/, 103G. 103M...Development area, 102YG, 102CG,
102MG, 103YG. 103CG, 103MG, 104Y(E, 104
CG, 104MG, 150YG. 150CG, 150MG, 152YG, 152c
G, 152MG, 154YG. 154CG, 154MG...Magnet.

Claims (1)

[Scope of Claims] n (n≧2) developing rollers each using a developer of a different color are arranged close to the latent image carrier, and each latent image on the latent image carrier corresponding to each color is In an image forming apparatus that obtains a color image by transferring and synthesizing sequentially developed visible images onto a recording medium in the order in which they are developed, each of the developing rollers is formed by a sleeve that can freely rotate in the forward and reverse directions, and a magnet that is immovably disposed inside the sleeve. The part of the sleeve that is in contact with the developer on the supply source side in the circumferential direction is defined as a developer collection area, and the area that closely faces the latent image carrier is defined as a development area. , The magnet is not disposed inside the sleeve for any one of the two intermediate regions between the agent collecting region and the developing region, and the magnet is not disposed inside the sleeve, and the magnet is not disposed inside the sleeve. , the magnet is arranged in the developing area, and for any one developing roller, during development, the sleeve is rotated in a direction from the agent collecting area to the intermediate area where the magnet is located, and the sleeve is rotated in a direction that advances from the agent collecting area to the intermediate area where the magnet is located, and A multicolor developing device characterized by rotating in a direction opposite to the above and at a low speed during development.