Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-03-09
2001-08-28
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06281915
ABSTRACT:
RELATED APPLICATION
This application is based upon the Japanese Patent Application No. 10-056616, the content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to an apparatus for propelling toner onto a recording medium such as paper to form images thereon. In particular, the present invention relates to an apparatus, using a recording material having toner and carrier, for propelling toner of the recording material to form images on the recording medium.
BACKGROUND OF THE INVENTION
Conventionally, there has been proposed one recording device for forming images on a recording medium such as paper. The device employs a recording material in the form of powder, made of toner and carrier. Typically, a particle size of the carrier is greater than that of toner. The device includes a bearing member for bearing the recording material, a backing electrode spaced a distance from the recording material born on the bearing member, and a substrate lying between the bearing member and the backing electrode. The substrate is formed with apertures through which the toner can pass and is provided with a plurality of individual electrode, each of which individual electrodes surrounding the aperture.
In such recording device, the toner and carrier are charged with opposite polarities by the contact with each other. In operation, a voltage having a polarity different from that of the toner is applied to the backing electrode, which forms an electric field for forcing the toner toward the backing electrode. An intensity of the electric field is not sufficient for the toner to separate from the carrier retaining the toner electrically.
In this state, once a voltage having a polarity different from that of the toner is biased to the selected individual electrode, the electric field is enhanced in the vicinity of the biased individual electrode. This enhancement of the electric field allows a part of toner opposing to the biased individual electrode to separate from the carrier and then propel toward the backing electrode through the corresponding aperture. Then, the toner passed through the aperture adheres onto a recording medium such as paper running between the plate and the backing electrode.
With this arrangement, the carrier made of magnetic material is normally held on the bearing member by a magnetic force generated between the carrier and the bearing member, though; a small amount of it can separate from the bearing member to drop onto the plate due to mechanical and electrical vibration, for example. Particularly, where the bearing member is supported above the backing electrode, more carrier will drop from the bearing member onto the substrate with the aid of the gravity applied thereto. Disadvantageously, the carrier on the plate may block the apertures due to its particle size that is greater than aperture. Eventually, this prevents the toner particles from the toner particles from being propelled through the blocked apertures, resulting in dot- defects degrading the resultant images.
SUMMARY OF THE INVENTION
To overcome this problem, a recording apparatus of the present invention includes a bearing member for bearing a recording medium having toner and carrier and a backing electrode opposing to the bearing member for electrically attracting the toner on the bearing member. The toner and carrier are charged to opposite polarities. A substrate having a plurality of apertures is provided between the bearing member and the backing electrode. This allows the toner to propel from the bearing member toward the backing electrode. Further, both the toner and carrier have respective volume mean diameters smaller than a diameter of the apertures, and the volume mean diameter of the carrier is larger than that of the toner.
In another aspect of the present invention, the carrier has more than about 70 percent of carrier particles having smaller diameter than the diameter of the apertures.
Also, in another aspect of the present invention, the substrate further has a plurality of control electrodes corresponding to the apertures, respectively, each of the control electrodes being for controlling the travel of the toner from the bearing member toward the backing electrode through one of the apertures.
REFERENCES:
patent: 5477250 (1995-12-01), Larson
patent: 6017116 (2000-01-01), Larson
Hiraguchi Hiroshi
Shibata Yoshifumi
Shimada Hirokatsu
Uno Koji
Yamaki Toshio
Barlow John
Gordon Raquel Yvette
Minolta Co. , Ltd.
Morrison & Foerster / LLP
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