JPH03293690A - Roller type developing head - Google Patents

Abstract

PURPOSE:To achieve simple and compact constitution by providing this roller type developing head with a developing roller made of magnetic substance, a band-shaped blade magnetized while dispersing magnetic particles in an elastic body, and a blade stopper, and positioning the blade by means of the blade stopper. CONSTITUTION:The developing roller 26 is a magnetic metallic roller. The magnetic blade 31 is made in such a manner that magnetic powder, permanently magnetized, is dispersed in a flexible material such as rubber or plastic, it is processed in the form of a sheet and magnetized, and then the sheet is cut in the form of bands. The stopper 30 projects above the inside base of a tray 25. The magnetic blade 31 stops in the position of the stopper 30, and slides on the developing roller 26 thereafter. Here, in the magnetic blade 31, pressurized contact against the developing roller 26 is produced by the magnetic force of the magnetic blade 31 itself, and its uniformity is high and extremely stable; since the supporting force for the blade 31 is produced by the magnetic force of the blade itself, no extra supporting mechanism is required. Thus, the supporting means for the blade is simplified, the blade acts on the developing roller while satisfactorily following it, and the occupancy areas of the blade and supporting means are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is a method of applying a developer in which toner particles are dispersed to an electrostatic latent image formed on the surface of a recording medium to make it visible. The present invention relates to a roller type developing device in which a rotatably supported developing roller capable of carrying a developing solution is disposed so as to face a recording medium with a small gap therebetween.

[Prior art] In order to visualize an electrostatic latent image formed on the surface of a recording medium by applying a developer containing toner particles dispersed therein, a rotatably supported developing roller and a recording medium are opposed to each other with a small gap between them. A roller-type developing head in which the roller is fed to the developing section is disclosed in Japanese Patent Application Laid-Open No. 60-28878 (USP 4454).
No. 833) and others.

FIGS. 7 to 9 are diagrams for explaining the basic structure of a known roller type developing device and problems that occur during development.

FIG. 7 is a diagram taken from the above-mentioned Japanese Patent Application Laid-open No. Sho Go-28678, in which a developing roller 2 is housed in a tray 1, a developer is supplied from a developer supply port 8, and is discharged from a drain port 9. The developing roller 2 faces the recording medium 5 positioned by the backup roller 4 with a minute gap of about 0.1 to 0.5 mm, and rotates at a speed of several hundred to several thousand revolutions per minute.

The developer is viscous and adheres to the surface of the developing roller 2, and is sent to a developing section indicated by G. Development is thus performed.

The roller development method maintains a narrow gap between the roller, which acts as a development electrode, and the recording paper, creating a strong potential gradient necessary for toner electrophoresis, and allows the developer solution to be efficiently sent to the development area. There are advantages. However, it is preferable to renew the high toner concentration liquid layer that remains on the roller surface where toner is not consumed facing the non-image area, and the liquid film on the roller surface that has become low concentration due to toner consumption. For this purpose, a doctor blade 3 is provided.

In addition, since developer is attached to the surface of the recording paper that has passed through the developing roller 2, it is preferable to collect this. A roller 10 is provided for this purpose.

Although the developing head shown in Fig. 7 above has excellent functions and effects, it is complicated and large, and if three or four developing heads corresponding to different color developers are arranged as in a color printer, However, there was a drawback that the installation space became very large.

In order to eliminate such drawbacks, the present applicant filed Japanese Patent Application No. 01-264.
In No. 248, a developing roller is housed in an airtight box, the box is provided with a developer supply port and a drain port, and a slit-shaped window is provided in each developing area, and the development is carried out by the suction action of a pump. We proposed a small and simple developing head that circulates the liquid and dries the recording paper.

Figures 8 and 9 are figures taken from the above application.

As shown in the figure, the developing roller 12 is housed inside 14 of the airtight box 13, and is rotatably supported by a drive shaft 12c. Reference numeral 11 denotes a slit-shaped window provided on the top surface of the box, and the surface of the developing roller 12 is exposed to the window 11 corresponding to the developing area. 15 is a developer supply port, 16 is a drain port, 17 is a developer reservoir, 18 is a suction pump, and 21a, 21b.

21c is each piping tinib, and P is a recording paper.

Thus, when the suction pump 18 is operated with the slit-shaped window portion 11 covered with the recording paper P, the hollow portion 1 of the box body 13
4 becomes negative pressure and the developer is sucked up and circulated. Further, since a negative pressure is applied to the slit-shaped window portion 11, the developing solution is suctioned and removed from the surface of the recording paper passing through the developing action at this portion. As a result, the recording paper P is sent out from the developing section in a dry state. Note that since the developing head section is under negative pressure, the developer is also prevented from scattering to the outside. A similar effect can be obtained by applying a blade to the developing roller 12 in the same manner as in FIG.

[Problems to be Solved by the Invention] The blade 3 shown in FIG. 7 supports an elastic sheet such as a polyurethane or polyester sheet on one side, and presses the other end against the surface of the roller 2. When a developing device with such a configuration is applied to a color electrostatic plotter where the recording paper width is close to 1 meter, the developing head becomes long, so the blade 3 must be supported uniformly on the circumferential surface of the developing roller 2. It's not easy. Particularly in the case of such a long developing roller, the roller itself often bends, but it is not easy to make the blade 3' act accurately by following this bending.

Further, since the blade 3 constantly slides on the developing roller 2 which rotates at high speed, there is a risk of wear and damage. Therefore, it is necessary to frequently replace the developing head with a new one, but in the case of a developing head housed in an airtight box as shown in Fig. 8,
Replacing blades is extremely difficult.

Further, as shown in FIGS. 8 and 9, providing a blade and a blade supporting means in a small and simple developing head complicates the internal structure.

In particular, if the structure was designed to emphasize the uniformity of blade support as described above, there was a drawback that the developing head would become larger.

Therefore, an object of the present invention is to provide a blade supporting means that is extremely simple, works well to follow the deflection of the developing roller, occupies a small space for the blade and the supporting means, and extends the durable life of the blade. Another object of the present invention is to provide a roller type developing head that is configured to be replaceable even when housed in an airtight box.

[Means for Solving the Problems] In order to solve the above problems and achieve the objectives, the present invention takes the following measures as basic means.

A developing roller made of a magnetic material is rotatably installed in a tray, and a magnetized sheet is formed by dispersing magnetic particles in an elastic material so that it is held by magnetic force on the surface of this developing roller. the surface of the developing roller escapes from the developer surface toward the upstream end of the developing action section from the position of the downstream end of the development action section when viewed in the rotational direction of the development roller; A blade stopper is provided between the blade and the blade stopper.

[Effect] As a result of taking the above measures, the following effects occur.

The blade is held on the surface of the developing roller by magnetic force.
At this time, the position is determined by the stopper. Since the blade is flexible, it adapts itself well to the surface of the developing roller and is attracted to it. Therefore, even when applied to a long developing head, it exhibits the function of reliably removing the developer.

Note that if the roller is rotated in the opposite direction to the direction used during development, the blade will move to any desired position while adhering to the roller surface, so it can be moved to a position where it is easy to perform operations such as replacement or other operations.

[Example] FIG. 1 is a diagram showing a first embodiment of the present invention.

In this figure, 25 is a tray, 26 is a developing roller, and 27 is a tray.
is a backup roller, 28 is a recording paper, 29 is a partition wall,
30 is a stopper, 31 is a magnetic blur, and 32 and 33 are a developer supply port and a liquid drain port, although not shown.

The developing roller 26 is a metal roller made of a magnetic material, and functions as a developing electrode. It supports the magnetic blade 31 and is pivoted to rotate in the direction of the arrow. The tray 25 has a surrounding wall and a partition wall 29 having a lower upper end surface. Thus, when the developer is poured from the developer supply port 32, the liquid level rises to the upper end of the partition wall 29, but is prevented from overflowing and becoming higher than that. The overflowing developer flows out from the drain port 33.

The magnetic blade 31 is made of a sheet-like material in which magnetic powder, such as ferrite, which becomes a permanent magnet is dispersed in a flexible material such as rubber or plastic. That is, the above material is magnetized and then cut into strips. The magnetic material may be left exposed on the surface of the magnetic blade 31, but in order to reduce the sliding frictional resistance on the surface of the developing roller 26, increase wear resistance, and make it adhere to the surface of the developing roller without gaps. It is more preferable to adhere or coat with non-magnetic plastic, rubber, etc. The stopper 30 is provided to protrude from the inner bottom surface of the tray 25, and a gap is provided between the stopper 30 and the developing roller 26 through which the magnetic blade 31 cannot pass. The stoppers 30 may be provided continuously in parallel to the axial direction of the developing roller 26, or may be provided discretely at intervals.

When the magnetic blade 31 is placed on the developing roller 26 from any easily accessible position above the tray 25 and the roller 26 is rotated in the direction of the arrow, the magnetic blade 31 moves to the position of the stopper 30 and is stopped. In other words, it is positioned. Thereafter, it remains at the stopper position and slides on the developing roller 26. When replacing the blade 31,
The developing roller 26 is rotated in the opposite direction and attachment/detachment work is performed at an easily accessible position.

The backup roller 27 transfers the recording paper 28 to the developing roller 26.
They are arranged to face each other with a small gap between them. When the developing roller 26 rotates in the direction of the arrow, the developer adhering to its surface moves to the developing area where the recording paper 28 and the developing roller 26 are closest. A liquid pool is then formed in this area. The developer that has consumed toner in the developing area moves while remaining attached to the surface of the developing roller 26 and enters below the surface of the developer again, but is not easily replaced by other liquid due to the viscous restraining force. When this restricted developer reaches the magnetic blade 31, it is forcibly removed by the blade 31. Fresh developer is again supplied to the roller surface that has passed through the blade 31 portion. In this way, the developer whose toner is not consumed is successively fed into the developing section, and a high developing ability is maintained.

Another function of the magnetic blade 31 is as follows. There is no electrostatic latent image on the surface of the recording paper 28, and any unconsumed toner or toner aggregates deposited on the surface of the developing roller are also removed from the surface of the developing roller 26. Always keep it clean. The toner density on the developing roller 26 is increased when a bias voltage is applied between the developing roller 26 and the recording paper 28 to prevent development fog in non-image areas, or when developing an image area. The electrostatic latent image charge is neutralized by the charge, and in the process of diffusing the latent image charge and the reverse magnetic charge that were restrained in the conductive processing layer of the recording paper 28, the conductive processing layer potential is changed, and the potential of the non-image area is changed. It also occurs when the recording paper potential is shifted to a potential in the direction of toner repulsion, and if left untreated, development fog will occur in non-image areas due to increased developer solution with high toner concentration.

By the way, in the magnetic blade 31 according to this embodiment, the pressing force against the developing roller 26 is generated by the magnetic force of the magnetic blade 31 itself, so the pressure is highly uniform and extremely stable. Further, the supporting force of the blade 31 is generated by the magnetic force of the blade itself, and there is an advantage that no special supporting mechanism is required. In addition, the required machining accuracy for the position and shape of the stopper 30 is loose, and even if the stopper 30 is slightly irregular, the flexible magnetic blade 31 is positioned along it, and the blade 31
The pressure welding action is almost unaffected and stable.

In this way, even if the blade 31 wears out due to long-term use, its effectiveness is not lost. Furthermore, even if it becomes necessary to replace the blade, it is extremely easy to attach and detach the blade. Therefore, the magnetic blade 31 is particularly suitable for constructing a long developing head.

Next, a second embodiment in which the magnetic blade 31 of this embodiment is applied to a suction circulation type roller type developing device as shown in FIG.
As shown in FIG.

In FIGS. 2 and 3, 34 is an airtight box, 35 is a slit window, 36 is a developer reservoir, 37 is a suction pump,
38a, 38b, and 38c each indicate a piping tube. Developing roller 26, magnetic blade 31, stopper 3
Since the configuration and operation and effects of 0 are the same as those shown in FIG. 1, a repeated explanation will be omitted.

When the suction pump 37 is operated with the slit window portion 35 of the airtight box body 34 covered with the recording paper 28, the recording paper 28 comes into close contact with the surface of the slit window 35.

Therefore, the inside of the hollow part of the airtight box body 34 becomes negative pressure, and from the developer storage container 36 to the piping tube 38a1 and the developer supply port 3.
The developer is sucked up via 2.

This developing solution fills part or all of the hollow space in the airtight box body 34, passes through the drain port 33, the piping tube 38b, the suction pump 37, and is circulated to the developing solution reservoir 36.

The airtight box body 34 has a slit window portion 35, a developer supply port 32,
The structure is sealed except for the drain port 33.

The developing roller 26 is rotated by rotating a shaft 26C supported by a sealed bearing.

When attaching the magnetic blade 31, the slit window 3
5, the blade 31 is placed on the roller 26 and magnetically attracted to it. Then, the roller 26 may be rotated in the direction of the arrow. Further, in order to remove the magnetic blade 31, it is sufficient to rotate the roller 26 in the opposite direction and carry it to the slit window portion 35.

The roller developing head of this embodiment has the function of suctioning and removing the developer from the surface of the recording paper 28 in addition to the developing function, and has a simple and compact configuration, and does not require multiple developing heads like a color printer. It is extremely suitable for such applications. By employing the magnetic blade 31, this roller type developing head can prevent an increase in the number of members and space required for mounting the blade 31, etc. Also blade 3
Difficult operations such as assembly and position adjustment of the first part can be omitted. Furthermore, despite the sealed structure, the blade 31 can be easily attached and detached, and the blade 31 has a long service life.

The developing device shown in FIGS. 2 and 3 is very convenient because it has the effect of collecting and removing the developer from the recording surface and drying the paper surface during development. However, if the operation of the suction pump 37 is stopped after the development is completed, the negative pressure is no longer applied.

In order to remove the developing solution adhering to the surface of the recording paper at this time, it is necessary to provide a suction drying means, a squeeze roller, etc. separate from the developing head.

FIGS. 4 and 5 show a developing device that allows the action of the magnetic blade 31 to continue suctioning and removing the developer from the surface of the recording paper even after the development is completed, and does not require an additional suction drying device. FIG. 2 is a diagram showing an example of a roller type developing head for realizing the above.

In Figures 4 and 5, 30a is the first stopper.
30b is a second stopper; 26a, 26b are roller shafts;
26c is a drive shaft, 40 is a bearing bush, 41 is an O-ring, 42 is a bearing, 43 is a bearing stop, and 44 is a developer level regulating end.

The magnetic blade 31 is assumed to be assembled when the developing head is assembled. The airtight box body 34 is constructed by joining sealing members 34b to both ends of the central member shown in FIG.

As in the second embodiment, the suction pump is operated to introduce the developer into the airtight box 34. When the liquid level rises above the developer level regulating end 44 for a while, the liquid drain port 33
Less and less air is being expelled from the Then, the proportion of the developer increases, and finally the amount of leaked air introduced through the slit window portion 35 and the amount of air discharged from the drain port 33 become equal. At this point, the liquid level will no longer rise.

During development, the roller 26 is rotated in the direction of the arrow.

The effect of the magnetic blade 31 at this time is the same as that shown in FIGS. 1 to 3. After the development is completed, when the developing roller 26 is rotated in the opposite direction with the suction pump operating, the magnetic blade 31 hits the second stopper 30b and stops.
At this position, it slides on the surface of the developing roller 26. If the developing roller continues to be rotated in this state, the surface of the developing roller carried by the developing roller 26 reaches the developing section with the developing solution removed. It then carries away the liquid from the puddle that has formed there.

When the recording paper is then conveyed, negative pressure is applied to the slit window portion 35, so that the developer adhering to the surface of the recording paper is removed by suction. Thereafter, the suction pump is stopped to complete a series of operations related to development.

In order to perform the above operations, please refer to Figures 4 and 5.
A roller development head of the configuration shown in the figures is extremely advantageous. This is because the magnetic blade 31 is magnetically attracted to the developing roller 26, so by reversing the rotating direction of the roller 26, the magnetic blade 31 can be moved so that its stopping position is above the developer surface. This is because the stopper position can be set.

In FIGS. 4 and 5, since the magnetic blade 31 is located between the first stopper 3081 and the second stopper 30b, it is necessary to attach the magnetic blade 31 before assembling the developing head. However, the configuration is such that the magnetic blade 31 cannot be replaced. However, it is easy to change this to a detachable structure.

FIG. 6 is a diagram showing a fourth embodiment that takes the above points into consideration. In FIG. 4, 51 is a fixed first stopper, 52 is a movable second stopper, and 53 is a second stopper positioning screw. The second stopper 52 is made of an elastic metal plate, has a lower end fixed to the airtight box 34, and an upper end bent toward the developing roller 26. When the positioning screw 53 is loosened, the second stopper 52 moves in a direction away from the roller 26, creating a space in which the magnetic blade 31 can freely pass through the second stopper 52. Therefore, it can be attached and detached at the window portion 35.

When the magnetic blade 31 is attached and fed to the bottom of the second stopper 52 and then the screw 53 is tightened, the gap between the tip of the second stopper 52 and the roller 26 is pinched, and the magnetic blade 31 is moved under the second stopper 52. can no longer pass through, and the same configuration as in FIG. 5 is realized.

It should be noted that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made without departing from the requirements of the present invention.

[Effect of the invention] According to the present invention, the following effects can be expected.

We have developed a roller type developing head that has a simple and compact configuration, has high developing efficiency, is easy to assemble and adjust, and has an airtight structure and is easy to apply to developing devices with a long developing width. realizable.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a first embodiment of the present invention. 2 and 3 are a side view and a sectional view showing the structure of a second embodiment of the present invention. 4 and 5 are cross-sectional views showing the structure of a third embodiment of the present invention. FIG. 6 is a sectional view showing the configuration of a fourth embodiment of the present invention. FIG. 7 to FIG. 9 are diagrams for explaining the prior art. 25...Tray, 26...Developing roller, 27...
Backup roller, 28... Recording paper, 29... Partition wall, 30... Stopper 31... Magnetic blade, 34... Airtight box body, 35... Slit window section, 36
...Developer reservoir, 37 is suction pump, 38g, 38
b, 38C...Piping tube, 40...Bearing is a bush, 41...0 ring, 42...Bearing, 4
3...Bearing stop, 44...Developer level regulation end,
51... Fixed type first stopper ~ 52... Movable second stopper 53... Stopper positioning screw.

Claims (3)

[Claims] (1) In order to visualize the electrostatic latent image formed on the surface of the recording medium by applying a developer in which toner particles are dispersed,
In a roller type developing device in which a rotatably supported developing roller is provided so as to be able to carry a developer on its surface and is arranged so as to face a recording medium with a small gap, the developing roller is rotatably provided in a tray. a developing roller made of a magnetic material, and a blade formed in the form of a belt of a magnetized sheet with magnetic particles dispersed in an elastic material so as to be held by magnetic force on the surface of the developing roller; Provided between the position of the downstream end of the developing action section as viewed in the rotational direction of the developing roller and the position where the surface of the developing roller escapes from the developer surface toward the upstream end of the development action section. 1. A roller type developing head, comprising: a blade stopper, the blade being positioned by the blade stopper. (2) A roller type developing head according to claim 1, wherein the tray is an airtight box having a developer supply port, a liquid drain port, and a slit-shaped window. (3) In the roller developing head according to claim 2, a developer level regulating end is integrally provided at the upper end of the drain port, and the developing roller is rotated in a direction opposite to the rotational direction during development. A roller type developing head characterized in that a second stopper is provided for positioning the blade by stopping it above the developer surface.