JPH01134484A - Developing device - Google Patents

Abstract

PURPOSE:To collect a carrier stuck onto a photosensitive material into a developing machine housing and to prevent the deterioration of a copy quality by providing a carrier recovering part for recovering the carrier on the photosensitive material in the developing machine housing. CONSTITUTION:At the position of the downstream side of a developing roll 2 in a developing machine housing 1, a carrier recovering member 7 is provided so as to be opposed to a photosensitive material 6, and a conductive catch-up roll 8 is supported so as to be freely rotatable in the direction reverse to the moving direction of the photosensitive material 6. Moreover, to the catch-up roll 8, a DC bias voltage whose polarity is opposite to the conductive polarity of a carrier 10 is applied, and also, a scraping member 11 is brought into contact with the surface of the catch-up roll 8. In this state, the carrier 10 stuck onto the photosensitive material 6 is eliminated by the rotating catch-up roll 8, scraped down by the scraping member 11 and dropped down onto a developer carrying member 4, mixed with a toner again and used as a developer. In such a way, it does not occur that the copy quality is deteriorated and the quantity of the developer is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device that develops an electrostatic latent image on a sensitive material using a two-component developer consisting of toner and carrier.

[Conventional technology]

As a developing device, a device that develops an electrostatic latent image on a sensitive material using a two-component developer consisting of toner and carrier is known.

[Problem that the invention seeks to solve]

With such a developing device, the carrier may be developed on the photosensitive material at the same time as the toner, and if the carrier remains developed on the photosensitive material, copy quality may deteriorate or the amount of developer may be reduced, so this is not preferable. do not have.

In particular, when a carrier with a small average particle size of 25 to 35 μm is used, the total surface area of the carrier can be increased, and a soft developer magnetic brush can be formed. ) and can obtain image quality with excellent line solid (Line 5 solid) reproducibility, but on the other hand, because the particle size of the carrier is small, the aforementioned adhesion to the surface of the photosensitive material occurs significantly. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a developing device that can remove and recover the carrier attached to the photosensitive material.

[Means and effects for solving the problem] A carrier recovery member for recovering the carrier on the photosensitive material is provided in the developing machine housing so that the carrier attached to the photosensitive material can be recovered into the developing machine housing. It is something.

〔Example〕

As shown in FIG. 1, a developing roll 2, a toner replenishing member 3, a developer conveying member 4, and a spike regulating member 5 are disposed inside the developing machine housing 1, and the surface of the developing roll 2 is covered with toner and carrier. A brush-like spike of two-component developer is formed, and the brush-like spike is brought into sliding contact with the electrostatic latent image on the photosensitive material 6 for development.

A carrier recovery member 7 is disposed at a position on the downstream side of the developing roll 2 in the developer housing 1, facing the photosensitive material 6, and the carrier recovery member 7 collects the conductive catch-up roll 8 from the photosensitive material. The catch-up roll 8 is rotatably supported in the opposite direction to the moving direction of the carrier 10, that is, in the opposite direction to the developing roll 2, and the catch-up roll 8 is connected to a DC bias power supply 9 to apply a DC bias voltage having a polarity opposite to that of the conductive polarity of the carrier 10. At the same time, a scraping member 11 is in contact with the surface of the catch-up roll 8.

The carrier 10 adhering to the photosensitive material 6 is removed by the rotating catch-up roll 8, and the carrier 1o on the catch-up roll 8 is scraped off by the scraping member 11 and falls onto the developer conveying member 4. , mixed with toner again and used as a developer.

FIG. 2 shows a second embodiment, in which the scraping member 11 is mounted diagonally so as to come into contact with developer spikes 2a on the developing roll 2.

In this way, the toner cloud in the developing device housing 1 can be prevented from scattering from between the developing roll 2 and the catch-up roll 8.

FIG. 3 shows a second embodiment of the carrier recovery member 7, in which a sleeve 13 is rotatably attached around a fixed internal magnet 12, and the carrier 10 is moved into the sleeve 13 by the magnetic force of the N pole of the internal magnet 12. The carrier ■0 is transferred together with the sleeve 13, and the repulsive magnetic field between the poles and the scraping member 11 are used to remove the carrier 13 from the sleeve 13.
It is designed to be removed from above and fall into the developing machine housing and song 1.

In this case, N, the magnetic force of the pole is ≧500G, and the scraping member 1
1 may be a magnetic material or a non-magnetic material.

Further, as shown in FIG. 4, the internal magnet 12 may be connected to the DC bias power source 9 to improve carrier recovery efficiency. At this time, the rotational speed of the sleeve 13 is equal to or higher than the rotational speed of the developing roll 2.

In addition, as shown in FIG. 5, the scraping member 11 is shaped like a pointed tip to improve scraping efficiency, and the scraping member 11 is made of an elastic material so that it is pushed against the surface of the catch-up roll 8 and the tip wears out. In this case, the roller 8 is caused to follow the elastic force and is constantly pressed against the surface of the catch-up roll 8.

FIG. 6 shows a third embodiment, in which an AC power source 14 and a DC power source 9 are connected to a conductive and magnetic catch-up roll 8, so that a DC electric field with a polarity that attracts carriers is superimposed on the AC electric field. .

By doing this, carrier 1 is caused by the AC electric field.
Since the power to electrically attract 0 becomes larger, the carrier 10 on the photosensitive material 6 can be sufficiently attracted and removed.

That is, the carrier 10 developed and attached to the photosensitive material 6 is attracted by the alternating electric field generated by the AC power source, but the toner image 15 developed on the photosensitive material 4 by the electric force is attracted.
will not be disturbed.

Next, a specific example will be explained.

When the sensitive material 6 is negatively charged, the toner is positively charged,
Carrier 10 becomes minus e.

Under these conditions, the photosensitive material 6 is moved at a speed of 300 am/see, the DC power source 9 is set to +500 V, and the AC power source 14 is set to 200 V.
00V, 100OV and frequency 500Hz, 10
00 Hz and 2000 Hz, the catch-up roll 8 is a conductive roll with magnetic force, and the gap with the sensitive material 6 is 0.1 mm, and the amount of Chiaria adhered to the sensitive material 6 after passing through the catch-up roll 8 is It was measured.

Incidentally, the DC superimposed potential and the AC potential were set as shown in the relationship shown in FIG.

Table 1 The results are as shown in Table 1. The carrier adhesion amount is expressed in a scale of 1 to 5, with 1 indicating a very small amount and 5 indicating a very large amount t'1.

From the above, when applying an AC electric field and a DC electric field, the larger the potential and the lower the frequency of the AC electric field, the better the carrier attraction is.If the DC electric field is not superimposed, the carrier attraction becomes worse.

From this, since the carrier attraction force due to the alternating electric field of the AC power source is strong, the magnetic force of the catch-up roll 8 can be eliminated and the carrier 10 can be attracted only by electric force, so the diameter of the catch-up roll 8 can be reduced. . That is, in order to apply magnetic force, it is necessary to make the diameter 16+a+s or more, but if magnetic force is not applied, the diameter can be made 16 mm or less.

Further, as shown in FIG. 6, a scraping member 11 is brought into contact with the catch-up roll 8 to scrape off and remove the sucked carrier and return it to the developing machine housing 1. If the scraping member 11 is magnetic, the magnetic force increases the binding force between the catch-up roll 8 and the scraping member 11, so that they are constantly brought into close contact with each other, and a space is created between them. This prevents the carrier from being removed from the surface of the catch-up roll 8. Of course, this is also effective when only DC power is applied.

〔Effect of the invention〕

Since the carrier 10 adhering to the photosensitive material 6 can be stored in the developing machine housing 1, the copy quality will not deteriorate and the amount of developer will not decrease.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing the first embodiment of the present invention, FIG. 2 is a configuration explanatory diagram of the second embodiment, FIGS. 3 and 4 are explanatory diagrams of different embodiments of the carrier recovery member, FIG. 5 is an explanatory diagram of the scraping member, FIG. 6 is an explanatory diagram of the configuration of the third embodiment, and FIG. 7 is a diagram showing application states of AC power and DC power. 1 is a developing machine housing, 6 is a photosensitive material, 7 is a carrier collection member, 8 is a catch-up roll, and 10 is a carrier. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] 1. A carrier collecting member 7 for collecting the developing roll 2 and the carrier 10 attached to the photosensitive material 6 in the developing machine housing 1.
A developing device characterized by being provided with. 2. Remove the carrier collecting member 7 from the carrier 1 on the photosensitive material 6.
2. The developing device according to claim 1, wherein the 0 is collected by magnetically, electrically, or magnetically and electrically attracted. 3. The developing device according to claim 1, wherein the carrier recovery member 7 is a conductive catch-up roll 8 to which a bias is applied. 4. The carrier collection member 7 is attached to the fixed internal magnet 1
2. The developing device according to claim 1, wherein a sleeve 13 is rotatably attached around the developing device.