Vibratory Bowl-toner Dispenser

Abstract

Toner feed mechanism for use in xerographic reproduction apparatus. The mechanism is characterized by the provision of a container and a structure for vibrating the container so that the toner is moved up an internally disposed, spiral ramp, toward an outlet where the toner phases from the container to a vertically disposed conduit communicating therewith. A screen is provided at the transition between the container and the conduit to prevent passage of irregularly shaped chips which serve to optimize the movement of toner to the outlet, and to effect return of the chips to a sump area in the container.

Description

BACKGROUND OF THE INVENTION

This invention relates, in general, to xerographic reproduction apparatus and, more particularly, to toner feed mechanism therefor.

More specifically, the invention relates to an improved toner dispenser that is particularly adapted for use in xerographic developing apparatus wherein, in order to develop the electrostatic latent image formed on the xerographic plate, it is required to dust the image with a developer powder, whereby the powder particles are selectively attracted to the charged areas of the plate to form a visible powder particle image of the electrostatic latent image.

In the process of Xerography, for example, as disclosed in Carlson U.S. Pat. No. 2,297,691, issued Oct. 6, 1942, a xerographic plate, comprising a layer of photoconductive insulating material on a conductive backing, is given a uniform electric charge over its surface and is then exposed to the subject matter to be reproduced, usually by conventional projection techniques. This exposure discharges the plate areas in accordance with the light intensity which reaches them and thereby creates an electrostatic latent image on or in the plate coating.

Development of the image is effected with developers which comprise, in general, a mixture of a suitable pigmented or dyed electrostatic powder, hereinafter referred to as toner, and a granular carrier material, the latter of which functions to carry and to generate triboelectric charges on the toner. In the development of the image, the toner powder is brought into surface contact with the coating and is held thereon electrostatically in a pattern corresponding to the electrostatic latent image. Thereafter, the developed xerographic image is usually transferred to a support material to which it may be fixed by any suitable means.

In the mixture of toner particles and carrier material, the toner particles, which are many times smaller than the carrier particles, adhere to and coat the surface of the carrier particles due to the electrostatic attraction between them. During development, as the powder coated carrier particles roll or tumble over the xerographic plate carrying an electrostatic image of opposite polarity to the charge on the toner, the toner particles are pulled away from the carrier by the charged image and deposited on the plate to form a powder image, while the partially denuded carrier particles pass off the plate. As toner powder images are formed, additional toner particles must be supplied to the developer mixture in proportion to the amount of toner deposited on the plate.

Toner material comprises pigmented resins which are plastic in nature and which may include plasticizing additives such as waxes or low melting resins, which tend to increase the agglomeration characteristics of the material. Consequently, when the toner is allowed to shift or when subjected to heat or high humidity, it tends to ball up or lump together in a mass. It has long been recognized that conventional dispensing apparatus and techniques are not suitable for use with toner material.

Systems utilizing gravity feed from a hopper specifically designed for use with toner have, heretofore, been provided with such things as thumping and sifting devices to overcome the aforementioned problems. Such devices, however, fall short of total acceptability, particularly, in applications where feeding through a small area is required, as, for example, where an auger type developer mixer is employed. Moreover, the rate of feed from hopper type structures is dependent upon the amount of toner in the hopper, therefore, the larger the amount of toner the higher the flow rate.

Accordingly, the general object of this invention is to provide for use in a xerographic machine, a new and improved toner dispenser.

It is a more particular object of this invention to provide a new and improved toner dispenser for feeding to a small area.

Another object of this invention is to provide a new and improved toner dispenser wherein the rate of dispensing is independent of the amount of toner in the dispenser.

Yet another object of this invention is to provide a new and improved toner dispenser, the flow rate of which can be selectively varied.

Still another object of this invention is to provide a new and improved toner dispenser capable of selectively dispensing a steady or intermittent flow of xerographic toner material depending upon the particular application of the dispenser.

BRIEF SUMMARY OF THE INVENTION

Briefly, the above-cited objects are accomplished by the provision of a generally cylindrically container having a spiral ramp on the inside wall thereof which extends from substantially the bottom to the top of the container. The container is mounted on a structure capable of periodically vibrating the container for effecting movement of toner contained therein from the bottom of the container to the top of the container via the spiral ramp. To enhance or optimize the movement of the toner up the ramp a plurality of metal chips having irregular shapes are provided. The chips are also moved up the ramp by the vibrations imposed by the support structure to thereby move toner particles of all sizes, even the smallest, up the ramp. The uppermost end of the ramp terminates in an outlet from the container which outlet communicates with a generally vertically oriented conduit through which toner emitted from the container is conveyed to a developer mixing section of the xerographic apparatus. The conduit is kept under proper vibration by virtue of its connection to the bowl thereby resulting in smooth passage of toner therethrough and therefrom. A screen suitable for passing toner but preventing passage of the chips through the outlet is provided to effect return of the chips to a sump area and to the tracks of the container in an optimum proportion for recirculation of the chips to thereby effect smooth toner transportation to the outlet.

Further objects and advantages of the present invention will become apparent when considered in view of the description of the preferred embodiment of the invention and the drawings forming a part hereof.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a toner feed mechanism representing the invention; and

FIG. 2 is a cross-sectional view taken on the line II--II of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, especially FIG. 1, reference character 10 designates generally a toner feed mechanism comprising a container 11 and an electromagnetic motor structure 12.

The container 11 comprises a base 13 provided with threaded openings 14 for receiving fasteners 16 for the purpose of securing the container 11 to the electromagnetic motor 12.

The bottom wall 13 comprises a large circular ring having a central opening 17 for receiving a ring member 18. The ring member 18 is constructed to support a floor member 19 which in this instance has a conically shaped cross section, the ring member engaging the cone of the floor member midway between the apex and the perimeter thereof. The ring member 18 is preferably secured to the conical floor 19 by continuously welding the same thereto. The ring member 18 may also be welded to the base plate or bottom wall 13, to support the floor 19.

The side of the bowl is constructed of a cylindrical wall 21 which is welded at its lower end to the bottom wall 13 as indicated at 22. The cylindrical wall 21 is likewise secured to the perimeter of the floor member 19 as indicated at 23. A ramp 24 is similarly attached to the inside of the cylindrical wall 21 and is shaped to form a spiral configuration extending between the top and bottom of the container. The ramp 24 is provided with short closed-in wall sections 26 at the lower extremity thereof in order to prevent lodging of material underneath the ramp and becoming bounded in the container.

At the upper end of the ramp 24 there is provided an opening 27 having a screen structure 28 supported thereat. Irregularly shaped metal chips 30 are provided in the container 11 to move toner 9, in a manner to be discussed hereinafter, up the ramp 24 toward the outlet opening 27 where the chips are prevented from traveling through the outlet and are moved back into the lower part or sump area of the container 11. A cover 29 is provided for the container 11 and a seal 31 disposed intermediate the cover and the container serves to prevent leakage of toner material from the container.

The electromagnetic motor structure 12 comprises a massive base 32 supported on resilient feed 33. The base 32 has sloping seats 34 disposed symmetrically about the vertical axis of the feeder mechanism. The seats 34 support springs 36, the upper ends of which are clamped to corresponding spring seats 37 on a frame 38.

The motor being of the electromagnetic type has a core 39 mounted on brackets 41 adjustably supported by bolts 42 on the base 32. The core 39 is C-shaped and has its coil or field windings 43 on the legs thereof. An armature 44 is secured to the underside of the frame 38. The core member is then adjusted to provide the proper air gap between its poles and the armature. Each energy pulse of the field pulls on the armature which causes the springs 36 to flex in an inclined arcuate path of movement, downwardly. When the energy impulse passes the springs return the container to its normal position. The momentum of the bowl and frame travels somewhat beyond the normal or static position but the springs are tuned to having natural period of vibration a few cycles off the frequency of the current impulses supplied to the field coil. Thus the container reciprocating in its inclined arcuate movement keeps in synchronism with the energy impulses. To decrease the period, the current impulses of an alternating current source are cut in half by employing half-wave rectifiers such as shown at 46. This rectifier and a reostat 47 are placed in series with the motor field coil and the source of alternating current supplied to control the magnitude of the reciprocation. A permanent magnet may be employed as the armature in place of the rectifier.

As the vibrations, as above discussed, are imparted to the container 11, it will be apparent that the chips and toner material will move up the ramp 24 toward the outlet opening 27, where the toner passes through the screen and the chips are prevented from passing through the opening and are thus returned to the sump area of the container. The outlet opening 27 communicates with a conduit 48 having a relatively small cross-sectional area and which is generally vertically oriented in order that toner introduced thereto will flow by gravity into a developer mixing structure, not shown, which may for example, be of the auger type in which case the lower end of the conduit 48 would be operatively associated with only one end of the mixing structure.

While the conduit 48 would, of necessity, be flexibly attached to the mixing structure to allow for vertical movement of the conduit as the container 11 moves up and down due to the vibrations imparted thereto by the electromagnetic motor, utilization of the present invention with other developer systems would dictate that at least the lower end of the conduit 53 be capable of movement relative to the developer hopper to thereby distribute the dispersed toner over the entire extent of the developer housing.

While the present invention has been described with reference to the structure disclosed herein, it is not intended that it be limited to the specific details and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or scope of the claims forming a part hereof. For example, a control device for pulsing the electromagnetic motor would be provided in order to add toner to the developer housing structure in accordance with toner depletion from the developer. Such would be accomplished through utilization of a comparison image which is developed the xerographic plate along with the image of a document being reproduced on the plate. Sensing of the comparison image by means of a photocell or the like, having a variable output, could be employed, through suitable components, to pulse the electromagnetic motor.

It will now be apparent that there has been provided a new and improved toner feed mechanism which is capable of continuously feeding at a nearly constant rate, toner materials, regardless of the amount of toner in the mechanism and the inherent nature of the materials and which can be fed through a relatively small area at various rates by adjustment of the rheostat 47.

Claims

What is claimed is:

1. Toner dispenser apparatus for use in xerographic reproduction apparatus, said apparatus comprising:

a container having a spiral ramp therein,

toner in said container,

means for imparting vibratory motion to said container whereby toner particles are moved up said ramp,

means constituting an outlet adjacent the top of said container for emitting toner from said container,

a plurality of irregularly shaped chips loosely disposed in said container for movement up said ramp to thereby push toner particles up said ramp,

and means for effecting return of said chips to a level below the top of said container for recirculation thereof, up said ramp.

2. Structure as specified in claim 1 wherein,

said means for effecting return of said chips comprises a screen supported at said outlet.

3. Structure as specified in claim 1 including,

a conduit of relatively small cross section communicating with said outlet for directing toner to a restricted area of a developer mixing structure.

4. Toner dispenser structure for use in xerographic reproduction, said dispenser structure comprising:

a container having toner disposed therein and a closed bottom and an outlet at the top,

a plurality of toner moving members loosely disposed in said container,

and means for continuously circulating said toner moving members from the bottom to the top of said container for dispensing of toner from said outlet.

5. Structure as specified in claim 4 wherein, said continuously circulating means comprises a screen supported across said outlet and an electromagnetic motor for imparting vibrations to said container.

6. Structure as specified in claim 5 including, a conduit of relatively small cross section communicating with said outlet for directing toner generally in a downward direction to a restricted area of a developer mixer structure.