JPH06149064A - Development housing for simultaneously performing pickup and trimming - Google Patents

Abstract

PURPOSE: To attract developing substance existing in an area where the developing substance is trimmed by adjusting the quantity of the developing substance carried by a carrying means in terms of a 1st magnetic pole and adjusting the quantity of the developing substance as soon as load is applied to the carrying means having the developing substance. CONSTITUTION: A carrying roll 85 is provided with a V-shaped magnet 84 positioned to be separated inside the tubular member of the roll 85 and attached so as not to be moved. By using the magnet 84, the tangential magnetic field of an area 84c is intensified more than on the area 84. Therefore, the developing substance adheres to the tubular member 80 on the area 84c, while the developing substance is released in an area 84d where the intensity of the tangential field is weaker when the member 80 is rotated. Thus, the developing substance is released from the member 80 in the area 84d where it is restored to the chamber 76, and mixed with the comparatively new developing substance by an auger. The S pole of the magnet 84 picks up the developing substance in the trim area and the N pole of the magnet 84 releases the developing substance in a load area.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates generally to electrophotographic printing machines, and more particularly to developing machines having magnets which are present in an area from which developing material is trimmed. Has a portion adapted to attract the developing material.

[0002]

SUMMARY OF THE INVENTION In accordance with one aspect of the present invention, there is provided an apparatus for developing a latent image on a surface, the developing apparatus including a housing defining a chamber for accumulating a replenishment material for a developer material. Means are provided for delivering the developer material from the chamber of the housing to the latent image. The conveying means includes a first magnetic pole having a first polarity and a second magnetic pole having a second polarity which is separated from the first magnetic pole and has a polarity opposite to the first polarity. The transport means generates a strong magnetic field on one area between the magnetic poles to hold the developing material therein and a weak magnetic field between the magnetic poles on the other area to release the developing material therefrom. A means is provided for adjusting the amount of the developing material conveyed by the conveying means for the first magnetic pole, applying a load to the conveying means having the developing material, and adjusting the amount at the same time.

[0003]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows details of an embodiment of the developing device 40. As can be seen, the developing device 40 includes a housing 44 that defines a chamber 76 therein for accumulating a replenishment material for the developer material. Donor roll 90 has electrical conductors located in grooves near its peripheral surrounding surface. The electrical conductors are substantially equally spaced from each other and isolated from the body of the electrically conductive donor roll 90. Donor roll 90 rotates in the direction of arrow 94. A transport roller, indicated by reference numeral 85, is also mounted in chamber 76 of developer housing 44. The transport roller 85 comprises a tubular member 80 adapted to rotate in the direction of arrow 92. An alternating voltage source (not shown) and a constant voltage source (not shown) electrically bias the donor roll 90 in the toner load region. The transport roller 85 is electrically biased by an AC voltage source and a DC voltage source. Donor roll 9
0 and the transport roller 85 have a relative voltage of
Provides an effective toner load on the donor roll 90 from the carrier granules attached to the tubular member.
This ensures that the donor roll 90 is properly electrically biased in relation to the electrical bias applied to the transport roller 85 in the load region 96 to attract toner particles from the carrier granules on the surface of the transport roller 85. To be taken. The transport roller 85 advances a certain amount of toner with a substantially constant charge onto the donor roll 90. This ensures that the donor roll 90 provides a constant amount of toner with a substantially constant charge to the development area. Augers 86 and 88 are rotatably mounted in chamber 76,
Mixing and transporting the developing material. These augers
The blade has a blade extending spirally outward from the shaft. These blades are designed to carry the developer material in a direction substantially parallel to the longitudinal axis of the shaft. Auger 86 rotates in the direction of arrow 87 and auger 88 rotates in the direction of arrow 89. Conveyor roller 85
Is more preferably aluminum, stainless steel, steel,
It includes a non-magnetic tubular member formed of plastic and having a rough surface around its exterior. An extended "bend bar" or V-magnet 84 is positioned within the tubular member and spaced from the tubular member. The legs of the V-shaped magnet form an obtuse angle. The magnet is mounted immovably. The tubular member rotates in the direction of arrow 92 and carries the developer material attached thereto to load area 94. In the loading area 94, toner particles are attracted to the donor roll from the carrier granules on the tubular member. The trim blade 82 is positioned very close to the transport roller 85 to maintain the compressed pile height of developer material on the transport roller 85 at the desired level. In this position, the trim blade 82 is inverted from the magnetic pole 84a of the magnet 84. Magnetism, that is, the pole 84a of the magnet 84
Are designed to attract, or pick up, the developer material. Since the trim blade 82 is positioned in the pickup area, the magnetic poles having the opposite polarities function as both the pickup and the trim magnetic poles. After being picked up and trimmed to a predetermined height, the developer material is transported onto the tubular member 80 and into the load area 96. The magnet 84 has another magnetic pole 84b arranged in the load region 96. The magnetic pole 84b has the opposite polarity to the magnetic pole 84a. By using a "bend bar", i.e. the V-shaped magnet 84, the tangential magnetic field of the bottom side of the transport roller 85, i.e. region 84c, is strengthened more than those above it, i.e. on region 84d. These regions ensure that the developer material will adhere to the tubular member 80 in the regions of the strong tangential field, ie region 84d, while
As the tubular member 80 rotates, release of the developer material is enabled in regions of weaker tangential field strength, i.e. region 84d. The magnetic force in this region is not strong enough to hold the developer material on the tubular member. In the area 84c,
The magnetic force is greater than the centripetal force that holds the developer material on the tubular member. Therefore, the developer material returns to the chamber 76 in the region 84.
At d, it is released from the tubular member 80 and mixed with the newer developer material from the auger. The south pole of magnet 84 picks up the developer material in the trim area, and the north pole of magnet 84 releases the developer material in load area 96. Chamber 76
The flow of developer material at is divided into two paths by the trib blade 82. One path is the transport roller 8
5 and the other path to the auger.

Another embodiment shown in FIG. 2 is a magnetic brush developing device. This apparatus uses a developing roll 130. The developing roll 130 conveys the developing substance from the chamber 1409 of the housing 134. Developing roll 130
Is adjacent to photoconductive drum 10 and forms a development area 136 therebetween. The roll 130 brings the developing material into contact with the electrostatic latent image at the development area 136. The latent image attracts toner particles from the carrier granules of the developer material to form a developed toner powder image on the photoconductive surface of drum 10. A toner dispenser (not shown) discharges unused toner particles into reservoir 132. The augers 120, 122 are rotatably mounted in the reservoir 132 and mix and transport the developer material. Developer roll 130 has a rotating tubular member with extended "bend bar" magnets 126 disposed therein.
Tubular member 124 rotates in the direction of arrow 138a and conveys the developer material to development zone 136. The magnet 126 is mounted immovably. The legs of the V-shaped magnet form an obtuse angle. The magnetic field generated by the magnet attracts the developer material from the chamber 140 of the housing 134 to the tubular member 134. In the development zone 136, toner particles are attracted from the carrier granules on the tubular member 124 to the electrostatic latent image recorded on the photoconductive drum 10. The trim blade 127 is positioned very close to the developing roll 130 and therefore maintains the compressed pile height of the developer material on the developing roll 130 at the desired thickness. In this position, the trim blade 127 is inverted from the magnetic pole 126a of the magnet 126. Magnetic pole 126a of magnet 126
Are designed to attract, or pick up, developer material. Since the trim blade 127 is located in the pickup area, the magnetic pole functions as both the pickup and the trim magnetic pole. After the development area is picked up and trimmed to a predetermined thickness, it is conveyed onto the tubular member 124 toward the development area 136. The magnet 126 has another magnetic pole 126b located in the development area 136. The magnetic pole 126b has the opposite polarity to that of the magnetic pole 126a. Once the developer material reaches the development area, the toner particles are attracted from the carrier granules to the charged area latent image. Thus, the latent image is developed using the toner particles.

By using a "bend bar" or V-shaped magnet 126, the tangential magnetic field in the lower, region 126c is stronger than those in the upper, region 126d. Thus, the developer material is released at the tubular member 124 in the region 126d so that it returns to the chamber 140 and is mixed with fresh developer material by the augers 120, 122. Thus, the S pole 12
6a picks up the developing material in the developing area 136. The flow of developer material in chamber 140 is split into two paths by trim blade 127. One path flows to the developing roll 130 and the other path flows to the auger.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a developing device used in the printing device of FIG.

FIG. 2 is a diagram showing another embodiment of a developing device used in the printing device of FIG.

[Explanation of symbols]

 40 Developing Device 44 Housing 76 Chamber 80 Tubular Member 82 Trim Blade 84 Magnet 85 Conveying Roller 90 Donor Roll

Claims (1)

[Claims] 1. A device for developing a latent image on a surface, comprising: a housing forming a chamber in which a replenishment material for a developing substance is accumulated; and means for conveying the developing substance from the chamber of the housing to the latent image. The first magnetic pole of the first polarity and the first
A second magnetic pole having a second polarity opposite to the first polarity and separated from the magnetic pole, generating a strong magnetic field on one region between the first magnetic pole and the second magnetic pole, and developing material And a carrier means for holding a magnetic field on it and releasing a developing substance by generating a weak magnetic field on the other region between the first magnetic pole and the second magnetic pole, and an amount of the developing substance conveyed by the conveying means. Adjusting means for adjusting the amount of the developer, the load being applied to the transporting means having a developing substance and the amount thereof being adjusted at the same time as the first magnetic pole. A developing device characterized by the above.