JPH0136619B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic developing device that uses a toner that is a mixture of a conductive toner and an insulating toner that occupies a different rank from the conductive toner in the triboelectrification series.

Conventionally, toners used for developing electrostatic latent images in electrostatic recording, electrophotography, etc. are toner particles whose main components are pigments or dyes and resin, and carriers consisting of fine ferromagnetic powder, glass globules, etc. So-called two-component toner, which is a mixture of toner and particles, has been used. Such two-component toners have the drawback that slight changes in the mixing ratio of toner particles and carrier particles have a large effect on the development results, and that fogging occurs when the ratio of toner particles becomes high. Another drawback was that when the carrier particles become fatigued, they adhere to the recording medium.

Furthermore, in recent years, so-called one-component toners that do not require carrier particles have come to be widely used in cases where there is no step of transferring a toner image, in order to overcome the drawbacks of the two-component toners.

Such one-component toner has (a) less toner scattering and (b) less fogging. (c) the developed image is clear, (d) the image density is constant, (e) there is little edge effect, (f) the developing device can be made smaller, (g) it is easy to maintain, etc. It has its advantages. However, since the one-component toner is conductive,
A drawback was that it was difficult to electrostatically transfer toner images onto plain paper.

In view of these circumstances, the toner described in JP-A No. 53-33633 contains conductive toner particles containing a ferromagnetic material;
A so-called mixed one-component toner is proposed, which is made by mixing insulating toner particles that have a lower conductivity than the conductive toner and occupy a different rank in the triboelectrification series from the conductive toner particles.

In this mixed one-component toner, conductive toner particles and insulating toner particles are charged to opposite polarities due to mutual friction. In addition,
The order of the conductive toner particles and the insulating toner particles in the triboelectric charging series is selected such that the charging polarity of the insulating toner particles is opposite to the polarity of the latent image to be developed formed on the recording member.

In this mixed one-component toner,
Development is achieved by depositing both insulating toner particles and conductive toner particles on the latent image area in a certain proportion, with the insulating toner particles being larger. Also,
Thereafter, when electrostatic transfer is performed, both types of toner particles are transferred from the recording member onto a transfer medium such as plain paper, again with a certain proportion of the insulating toner particles being larger.

Such a mixed one-component toner is mixed with insulating toner particles, so it can perform the electrostatic transfer well, and has almost the same advantages as the conventional one-component toner. .

In order to perform development using this mixed one-component toner, the toner is supplied to the outer peripheral surface of a sleeve containing a magnet, and a magnetic brush made of toner particles is formed on the outer peripheral surface of the sleeve. The equipment is optimal.

However, in this type of conventional developing device,
Since toner was retained on the sleeve even during non-development, the following drawbacks occurred.

(b) As the conductive toner particles and the insulating toner particles attract each other by Coulomb force, the toner tends to block on the sleeve during non-development, and this blocked toner stabilizes the toner to the developing area. impede supply.

(b) During non-development, residual charges due to the previous history of the recording member are developed.

(c) When the developing device is taken in and out of the main body of a recording device such as a facsimile machine or a copying machine for toner replenishment or maintenance inspection, the toner on the sleeve may spill into the main body of the device.

The present invention has been made to solve the above-mentioned conventional drawbacks, and uses a mixed one-component toner, can prevent toner blocking on the sleeve, and requires extra waiting time during recording. An object of the present invention is to provide an electrostatic developing device that does not require.

The present invention will be described below based on embodiments shown in the drawings.

In FIG. 1, the upper part of a container 1 is provided with a toner replenishing port 2, an opening 3, and mounting guide plates 4, 5 for accommodating this apparatus in the main body of a facsimile machine, a copying machine, or the like. A lid 6 is detachably attached to the toner supply port 2.

A toner carrier 8 having an appropriate number of toner carrier plates 7 provided on its outer periphery is rotatably accommodated in the container 1 at a position below the toner supply port 2, and this toner carrier 8 is not shown in the figure. It is configured to rotate in the direction of arrow A.

Also, out of the container 1, a toner carrier 8
A sleeve 9 made of a non-ferromagnetic material is rotatably housed on the upper side, and this sleeve 9 is rotated by a drive device (not shown) in the opposite direction to arrow B at the start of development, and then in the same direction as arrow B. driven to do so. A portion of the sleeve 9 has the opening 3
This projecting portion is opposed to the drum-shaped recording member 10 .

Inside the sleeve 9, there is a suitable number of N on the outer peripheral surface.
Magnet roll 1 with alternating poles and south poles
1 is rotatably housed, and this magnet roll 11 is driven by a drive device (not shown) and is configured to rotate in the same direction as the arrow B independently of the sleeve 9. When the development is completed, the rotation is stopped after the sleeve 9 by controlling the drive device by a control means (not shown).

A toner stopper 12 and a toner peeling blade 13 are in sliding contact with the outer peripheral surface of the sleeve 9. Further, a toner collection roll 14 is rotatably housed below the sleeve 9 in the container 1, and this toner collection roll 14 is driven by a drive device (not shown) in the direction of arrow C. It is driven by and rotates in the direction of arrow C.

Further, a mixed one-component system and toner are supplied into the container 1 from a toner supply port 2 . In this example, 100 parts by weight of a bisphenol type epoxy resin and 250 parts by weight of ferromagnetic particles were added to a commercially available one-component toner.
Conductive toner particles were prepared by mixing parts by weight, while insulating toner particles were prepared by mixing 100 parts by weight of styrene resin and 60 parts by weight of ferromagnetic particles with a commercially available one-component toner. A mixture of conductive toner particles and insulating toner particles obtained in 1:1 to 1:3 is mixed in the mixture 1.
It was used as a component toner. The conductive toner particles had a particle size of 10 to 40 μm, and the insulating toner particles had a particle size of 10 to 44 μm.

Next, the operation of this embodiment will be explained. The mixed one-component toner contained in the container 1 is supplied to the outer peripheral surface of the sleeve 9 by the toner carrier plate 7 as the toner carrier 8 rotates. . Here, assuming that the sleeve 9 is stationary and only the magnet roll 11 rotates, the toner supplied onto the outer circumferential surface of the sleeve 9 is moved onto the outer circumferential surface by the rotating magnetic field based on the rotation of the magnet roll 11. The net is conveyed in a direction opposite to the rotational direction of the net roll 11 (in a direction opposite to arrow B). on the other hand,
When the magnet roll 11 is stationary and only the sleeve 9 rotates, the toner supplied onto the outer peripheral surface of the sleeve 9 is rotated in the direction of rotation of the sleeve 9 due to the frictional force between the outer peripheral surface and the toner. transported in the same direction.

Then, the sleeve 9 and the magnet roll 1
1 rotate at the same time, the toner on the sleeve 9 has two flow layers, upper and lower, which flow in opposite directions. That is, on the lower layer side, a flow is generated in the same direction as the rotation direction of the sleeve 9 due to the rotation of the sleeve 9, while on the upper layer side, a flow is generated in the opposite direction to the rotation direction of the sleeve 9 due to the magnet roll 11.

Now, in the present invention, at the start of development, the sleeve 9 is rotated in the opposite direction to the magnet roll 11 by the control means, so that the toner supplied onto the sleeve 9 from the toner carrier plate 7 is rotated by the rotation of the sleeve 9. The image is transported over the sleeve 9 in a direction opposite to the rotating direction of the magnet roll 11 due to the transport force of the magnet roll 11 and the magnetic transport force of the magnet roll 11. Department).

Next, after a certain period of time has elapsed, the sleeve 9 rotates in the same direction as the magnet roll 11 (in the direction of arrow B), and as a result, two toner particles in opposite directions are placed on the sleeve 9 as described above. A flow occurs.

A part of the toner supplied onto the sleeve 9 by the toner carrier plate 7 is conveyed over the sleeve 9 while forming a magnetic brush by the flow in the opposite direction to the arrow B by the magnet roll 11, and is conveyed to the developing section. A portion of the latent image is then attached to the latent image formed on the outer peripheral surface of the recording member 10. Further, the remaining toner that is not attached to the latent image among the toner flowing in the opposite direction to the arrow B passes through the developing section and reaches the toner stopper 12, where it is separated from the sleeve 9 and placed in a container. 1 and falls back toward the toner carrier 8 by the rotation of the toner collection roll 14.

On the other hand, the other part of the toner supplied onto the sleeve 9 is conveyed on the sleeve 9 in the direction of arrow B by the flow caused by the rotation of the sleeve, reaches the toner peeling blade 13, and is removed from the sleeve 9 by the blade 13. The toner is separated and falls towards the bottom of the toner container 1, and is returned to the toner carrier 8 by the rotation of the toner collection roll 14 (the above explanation is based on the macroscopic view of the two flows of toner on the sleeve 9). When looking at individual toner particles, they move from one flow to the other.) Here, the conductive toner particles and insulating toner particles in the toner on the sleeve 9 are , the two flows rub against each other and are sufficiently charged to different polarities. Therefore, each toner particle adheres to the latent image on the recording member 9, that is, development is performed satisfactorily.

In addition, the magnet roll 11 and the sleeve 9
are rotated at the same time, the amount of toner supplied to the developing section is determined from the amount of toner supplied onto the sleeve 9 by the toner carrier plate 7 to the amount of toner supplied onto the sleeve 9 by the toner peeling blade 13.
This is the amount above minus the amount of toner removed. In other words, the amount of toner supplied to the developing section is the same as that between sleeve 9 and magnet roll 11.
Determined by the number of rotations.

Next, at the end of development, the control means:
First, only the magnet roll 11 is stopped. As a result, the flow in the direction opposite to the arrow B is eliminated, and all the toner on the sleeve 9 is conveyed in the direction B.
Sequentially, the sleeve 9 is removed by the toner peeling blade 13.
Therefore, after a certain period of time has elapsed after the magnet roll 11 has stopped, there is no more toner on the sleeve 9, and after this, the rotation of the sleeve 9 is also stopped by the control means.

Note that the toner image formed on the recording member 10 by the developing operation is transferred to a transfer medium such as plain paper.

As described above, in this apparatus, when not developing,
Since the toner is removed from the sleeve 9, toner blocking does not occur on the sleeve 9 even when a mixed one-component toner is used. In addition, residual charges due to the previous history of the recording member 10 are not developed during non-development.

Furthermore, when this device is removed from the facsimile device main body or copying machine main body, etc. for replenishing toner to the container 1 or for maintenance and inspection, etc.
There is no possibility that toner will spill from the top of the sleeve 9 into the main body of each device.

Note that even when the magnet roll 11 and the sleeve 9 start rotating simultaneously and in the same direction at the start of development, toner is supplied to the developing section. However, in this case, the sleeve 9 is moved to the magnet roll 11 at the start of development as in the present apparatus.
It takes longer for the toner to reach the developing section than when the toner is rotated in the opposite direction, requiring extra holding time.

To give a specific example, Magnetrol 11
The rotation speed of sleeve 9 is 1800 rpm, and the rotation speed of sleeve 9 is 1800 rpm.
At 30 rpm, when the magnet roll 11 and sleeve 9 start rotating at the same time, it takes about 4 seconds from the start of the rotation until the toner is supplied to the developing section.

However, if the sleeve 9 is rotated in the opposite direction to the magnet roller 11 for a certain period of time at the start of development, the sleeve 9 and the magnet roller 11 can be rotated for a certain period of time.
Toner is supplied to the developing section approximately 0.8 seconds after the start of rotation.

Then, the time of about 0.8 seconds is sufficiently processed so that it does not become wasted time, for example by adjusting the time it takes for the latent image on the recording medium 10 to reach the developing section or the timing of the start of recording. It's time to do it.

As is clear from the above description, the electrostatic developing device according to the present invention has the following effects by being configured so that no toner is present on the sleeve during non-development.

(a) Even when a mixed one-component toner is used, the toner does not block on the sleeve during non-development.

(b) Residual charges due to the previous history of the recording member will not be developed.

(c) When the developing device is taken in and out of the main body of a recording device such as a facsimile machine or a copying machine for toner replenishment or maintenance inspection, the toner on the sleeve does not spill into the main body of the device.

Furthermore, since the sleeve is rotated for a certain period of time in the opposite direction to the rotation direction of the magnet at the start of development,
Because the conveyance force due to the rotation of the sleeve and the conveyance force of the magnetic force due to the rotation of the magnet act on the toner, toner can be supplied to the developing section extremely quickly, significantly reducing the extra waiting time during recording. can.

[Brief explanation of drawings]

The drawing is a sectional view of an electrostatic developing device according to an embodiment of the present invention. 1... Container, 7... Toner carrier plate,
8...Toner carrier, 9...Sleeve, 10...
...Recording member, 11... Magnet roll, 13...
...Toner peeling plate.

Claims (1)

[Claims] 1 A rotatably installed sleeve and multiple S
a cylindrical magnet having poles and N poles alternately formed on its outer peripheral surface and rotatably housed in the sleeve in the same direction; conductive toner particles containing a ferromagnetic material; A toner obtained by mixing insulating toner particles having a lower conductivity than the conductive toner particles and occupying a different rank than the conductive toner particles in the triboelectrification series, and supplying the toner to the outer peripheral surface of the sleeve. a toner supplying means for rotating the sleeve; a toner peeling means slidingly contacting the outer circumferential surface of the sleeve; and at the start of development, the sleeve is once rotated in a direction opposite to the magnet;
An electrostatic developing device comprising: a control means for rotating the magnet in the same direction as the magnet, and for stopping the rotation of the magnet before the sleeve when development is completed.