JPH0447825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a multicolor recording device employing an electrophotographic method, and particularly to improvements in its developing device.

(2) Background of the technology As an example of a multicolor recording device, the schematic configuration of a two-color recording device is shown in FIG. 1. Along the surface of the recording drum 1 rotating in the direction of arrow A, a first latent image is formed by irradiating a corotron 2 for uniformly charging the drum surface and light in the direction of arrow B according to the image to be recorded. a first exposure device 3 for developing the first latent image; a first developing device 4 for developing the first latent image; and a first developing device 4 for developing the first latent image, and irradiating light in the direction of arrow C according to the image to be recorded to form a second latent image. a second developing device 6 for developing the second latent image in a color different from that of the first latent image; and a second developing device 6 for developing the second latent image in a different color from the first latent image. A transfer corotron 7 for transferring, a static eliminating corotron 8 for eliminating static toner remaining on the recording drum 1, and a cleaner 9 for removing residual toner.
A static elimination lamp 10 for eliminating static electricity from the surface of the recording drum 1 is provided. A two-component developer is generally used for developing an electrostatic latent image, which is a mixture of toner made of a non-magnetic material and a carrier made of iron powder or the like for transporting the toner by the action of a magnetic roller. However, the developer in the second developing device of a two-color recording device is susceptible to destruction of the toner image on the first latent image by the carrier, scraping of the toner, or drawing of the toner on the drum into the second developing device. In order to prevent this problem, the present inventors have proposed a two-color recording method using a one-component magnetic toner developer that does not contain a carrier.
However, even in a developing device using such a one-component developer, variations in the contact depth between the toner and the recording drum caused by misalignment of the second developer, surface potential of the recording drum, development bias, etc. Toner of the first developer may get mixed into the second developer due to potential fluctuations. In addition, if the contact interval between the magnetic roller of the first developing device and the recording drum is inappropriately set, or if the initial charging potential is too high, the carrier of the first developing device will adhere to the recording drum. do. The carrier deposited on the recording drum is attracted by the magnetic roller of the second developing device, transferred to the second developing device, and mixed into the one-component developer of the second developing device. Carrier is iron powder with a particle size of 100 to 300 μm,
If it gets into the second developing device, it will clog the space (100 to 150 μm) between the sleeve on the outer periphery of the magnetic roller and the doctor blade for setting the thickness of the toner layer. When such clogging occurs, the magnetic toner is not uniformly supplied, resulting in white spots on the recorded image and poor recording.

(3) Prior art and problems In the developing device of a conventional two-color recording device, in order to deal with the deterioration of recording quality and the deterioration of color freshness due to the contamination of carrier into the second developing device or the transfer and adhesion of different color toner, etc. The one-component developer in the second developing device was frequently replaced, and the surface of the sleeve of the developing roller was manually cleaned each time. Such maintenance work is troublesome and also wastes developer.

(4) Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to provide a developing device in which toner in a first developing device can be easily removed and recovered.

(5) Structure of the Invention In order to achieve the above object, according to the present invention, a first development process is performed using a two-component developer consisting of toner and a magnetic carrier, and then a first development process is performed using a magnetic one-component developer. A developing device that performs a second developing process includes a developing roller for conveying a magnetic one-component developer to a developing area, and a developing roller in the developing area. A multi-color recording device is provided, comprising a blocking plate applied to the developing roller surface to remove magnetic carriers adhering to the surface from the developing roller surface.

(6) Embodiments of the invention Figure 2 shows a developing device (second developing device) according to the present invention.
FIG. The second developing device 6 has a magnetic roller 12 and a sleeve 13 disposed around the outer periphery of the magnetic roller 12. When the magnetic roller 12 is rotated in the direction of arrow D, magnetic toner 14 is caused to flow onto the sleeve 13 in the direction of arrow E due to its magnetic action. move. A doctor blade 15 for adjusting the thickness of the magnetic toner 14 facing the recording drum 1 is provided on the outer periphery of the sleeve 13 on the upstream side of the portion facing the recording drum 1 rotating in the direction of arrow A. Further, on the outer periphery of the sleeve 13 on the downstream side of the part facing the recording drum 1, there is also a carrier 1 that has been transferred from above the recording drum 1 onto the sleeve 13.
A blocking plate 16 is provided to prevent the developer 7 from getting into the second developing device 6 . The spacing between the sleeves 13 of the blocking plates 16 is set to a distance corresponding to the grain size of the carrier 17 to prevent intrusion into the interior of the carrier 17. By providing such a blocking plate 16, the carrier 17 from the first developing device attached to the sleeve 13 is not mixed into the second developing device, thereby preventing clogging by the carrier on the back side of the doctor blade 15. There isn't. sleeve 1
3 is further provided with a shutter 1 for stopping the flow of the movable magnetic toner 14 as shown by arrow F.
8 is provided.

The blocking plate 16 may be rotatable in the direction of arrow G as shown in FIG. 3, and the distance from the sleeve 13 may be variable. With such a configuration, the blocking plate 16 is brought into contact with the sleeve 13 periodically, and the sleeve 13 is rotated in the direction of arrow H to close the sleeve 13.
The small carrier particles attached thereto can be removed and stored in the collection box 19. At this time, if the flow of the magnetic toner 14 is stopped by the shutter 18, the magnetic toner 14 will not be removed by the blocking plate 16, thereby preventing wasteful collection of the magnetic toner.

As another means of recovering Carrier 17,
As shown in the figure, a vacuum suction duct 20 may be provided on the blocking plate 16, and the carrier 17 may be sucked in the direction of arrow P by a vacuum pump (not shown) and stored in the collection box 19.

By using such means of the blocking plate 16, the second
A configuration that enables removal of the non-magnetic toner of the first developing device adhering to the sleeve 13 of the developing device 6 will be described with reference to FIGS. 5 to 8. FIG. The blocking plate in this case is substantially constituted by the rubber blade 21. A suction port 20a communicating with the suction duct 20 is provided on the upper surface of the rubber blade 21. The non-magnetic toner 22 (FIG. 7) transferred from the recording drum 1 onto the sleeve 13 does not move even when the magnetic roller 12 rotates in the direction of arrow D because it is non-magnetic and remains stationary on the sleeve 13 and accumulates there. . The rubber blade 21 connected to the above-mentioned suction duct 20 is normally arranged at a distance from the sleeve 13 at an interval that prevents the passage of the carrier, as in the case of the above embodiment, and prevents it from entering the inside of the carrier. do. When the non-magnetic toner 22 adheres to the sleeve 13 to some extent, the shutter 18 is brought into contact with the sleeve 13 to stop the flow of the magnetic toner 14 and remove the magnetic toner from the non-magnetic toner-adhered portion of the sleeve 13 (FIG. 7).
In this state, move the rubber blade 21 in the direction of the arrow Q to bring it into contact with the sleeve 13.
3 in the direction of the arrow H, the non-magnetic toner 22 adhering to the sleeve 13 is attracted and removed by the suction duct 20 in the direction of the arrow P.

(7) Effects of the Invention As explained above, in the developing device according to the present invention, since the blocking plate is provided to prevent the carrier from being mixed into the inside of the developing device, the mixing of the carrier into the one-component developer is prevented. This prevents deterioration in recording quality due to clogging, and also lengthens the developer replacement cycle, making maintenance work easier and eliminating waste of developer. In addition, this carrier blocking plate is provided at a variable interval with respect to the sleeve, and the shutter,
By providing a suction duct or the like, the non-magnetic toner of a different color attached to the sleeve of the first developing device can be removed, thereby further facilitating maintenance of the developing device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a two-color recording device to which the present invention is applied, FIGS. 2 to 4 are block diagrams of different embodiments of a developing device according to the present invention, and FIGS. The figures are a front view and a side view of an example of the blocking plate according to the present invention, and FIGS. 7 and 8 are explanatory views showing different usage states of the blocking plate shown in FIG. 5, respectively. 1... Recording drum, 4... First developing device, 6...
Second developing device, 12... Magnetic roller, 13... Sleeve, 14... Magnetic toner, 16... Blocking plate, 17... Carrier, 20... Suction duct, 2
1...Rubber blade.

Claims (1)

[Claims] 1. A multicolor recording device that performs a first development process using a two-component developer consisting of toner and a magnetic carrier, and then performs a second development process using a magnetic one-component developer, wherein the second A developing device for carrying out a developing process includes a developing roller for conveying a magnetic one-component developer to a developing area, and a magnetic carrier applied thereto to remove a magnetic carrier attached to the developing roller surface in the developing area from the developing roller surface. 1. A multicolor recording device characterized by comprising a blocking plate.