Magnetic Powder Filler Port

Abstract

In the throat of a filler port for a reservoir for magnetizable powder, there is provided a magnetic-valve-type arrangement for preventing the escape of the powder cloud generated during loading of the powder from a nozzled filling container of cooperating design. The magnetic valve arrangement is activated to trap the powder whenever the filling port cover or the nozzle of the filling container is removed from the port opening.

Description

BACKGROUND OF THE INVENTION

This invention relates to receptacles for magnetic powder. The invention has particular application to magnetic printing and/or display devices. Such devices are well known, and essentially comprise a magnetizable surface, such as the surface of a drum or belt, which can be selectively magnetized in accordance with the matter to be printed or displayed, the surface then being "dusted" with magnetic powder which adheres to the magnetized parts so forming a powder "image." The dusted surface may then be used directly for display of the powder image, or it may be used as a printing element for transferring the image to a further surface such as a paper tape or sheet. In this context the term receptacle is to interpreted broadly as meaning any part of the device into which magnetic powder is received from outside the device.

SUMMARY OF THE INVENTION

According to the present invention there is provided a receptacle for magnetic powder, including a filler port having switchable magnetic means at the port opening to trap magnetic powder tending to emerge therefrom.

BRIEF DESCRIPTION OF THE DRAWING

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which:

FIG. 1 is a cutaway perspective view of a filler port for a receptacle according to the invention, and a portable filling container therefor; and

FIG. 2 is a cross section of the filler port of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, a filler port 1 extends through a wall 2 of a receptacle for magnetic powder. The wall 2 can be a wall of a magnetic printing and/or display device. The filler port comprises an inclined rim 3 and a tubular body 4 which converges inwardly at 5 on the inside of the receptacle. The rim 3 and body 4 may both be molded from plastics material. The filler port has a cover 13 (FIG. 2) which is fitted to the port by means of a bayonet fitting.

For replenishing the supply of powder in the receptacle a portable filling container 6 is provided. This has an outlet nozzle 7 which is normally sealed by a spring-loaded valve 8, and is adapted to be inserted into the opening 9 of the filler port. The filler port further includes a stop member 10 in the port opening 9, supported by a "spider" 11 from an annular member 12. The spider 11 and annular member 12 may be molded in one piece from plastics material. The stop member 10 enters the nozzle 7 when the latter is inserted into the port opening 9, thereby opening the valve against the spring bias and allowing magnetic powder to pass into the receptacle from the container 6. The valve 8 closes again when the nozzle 7 is withdrawn.

While the receptacle is being filled from the container 6, the agitation of the powder inside the receptacle by the powder falling from the container causes a turbulent cloud of magnetic powder inside the receptacle. To prevent this cloud escaping from the port or at least to reduce the amount of powder that escapes, particularly after the container 6 is removed and before the cover 13 is replaced, switchable magnetic means are provided at the port opening 9 to attract and therefore trap magnetic powder tending to emerge from the opening.

In this embodiment the switchable magnetic means takes the form of an annular electromagnet 14 disposed between the rim 3 and the annular member 12 and surrounding the port opening 9. The windings 15 of the electromagnet are energized automatically when the cover 13 is removed, and deenergized when the cover is replaced. This is achieved by means of an electric switch 16 (FIG. 2) actuated by the cover.

Magnetic powder tending to emerge from the opening 9 is thus attracted towards the poles 17, 18 (FIG. 2) of the electromagnet, and to prevent powder penetrating into the magnet windings a nonmagnetic sleeve 19 is provided. Any powder adhering to the sleeve 19 falls back into the receptacle when the lid 13 is replaced and the electromagnet thus deenergized.

When supplying powder to the receptacle, the nozzle 7 of the container 6 extends into the port opening beyond the electromagnet. Thus the powder only comes under the influence of the magnetic field within the nozzle, and the weight of powder in the container 6 ensures that this field does not prevent the powder leaving the container. However, the field within the nozzle could be reduced if necessary by making the latter of a high-permeability magnetic material, so screening its interior from the field of the electromagnet.

Alternatively, it could be arranged that insertion of the nozzle into the port opening deenergizes the electromagnet in a similar way to the replacing of cover 13, withdrawal of the nozzle causing the electromagnet to be reenergized.

Other arrangements to that described with reference to the drawings are of course possible. In particular, it is envisioned that instead of an electromagnet as the switchable magnetic means, a switchable permanent magnet or magnets could be used, operating by the same principle as magnetic chucks on machine tools, i.e. using a movable screen. As before the switching could still be accomplished automatically by the cover and if required the portable container, although in this case mechanically.

Automatic switching of the magnetic means is not of course necessary; this could be performed manually when required by the person filling the receptacle.

Claims

What is claimed is:

1. In conjunction with a port opening of a receptacle for receiving magnetic powder, a filler port arrangement comprising a filler port and a filler port cover, switchable magnetic means, situated at the port opening and arranged around the edge thereof, for trapping, upon actuation, magnetic powder tending to emerge from the receptacle, said magnetic means being arranged to be automatically actuated whenever the port opening is uncovered and automatically switched off when the port opening is covered.

2. The arrangement according to claim 1 further including trigger means coupled to and controlling said magnetic means, said trigger means being positioned substantially at the edge of the port opening to be operative with a port opening cover of cooperating design, and causing said magnetic means to be automatically actuated whenever the port opening cover is removed.

3. The arrangement according to claim 2 wherein said magnetic means include an electromagnet, which, when the port opening is tubular in construction, is arranged annularly about the port opening.

4. The arrangement according to claim 3 further including a nonmagnetic sleeve, arranged to be in front of and to cover said magnetic means, for preventing magnetic powder from contacting said magnetic means.

5. The arrangement according to claim 2 wherein said filler port arrangement further includes a funnel-shaped guide top portion for directing the nozzle of a filling container of cooperating design into the port opening.

6. The arrangement according to claim 5 wherein said filler port arrangement further includes a fixedly arranged stop member positioned substantially in the center of the port opening and arranged to open the nozzle of a filling container when the latter is inserted into the port opening.

7. A magnetic powder-handling system comprising in combination a filler port arrangement for a magnetic powder receptacle, said filler port arrangement having a filler port and a filler port cover switchable magnetic means positioned at the port opening of the receptacle and actuated in order to prevent the escape of the powder from the receptacle whenever the port is uncovered, and a portable filling container constructed to cooperate with said filler port arrangement and having an elongated outlet nozzle normally sealed by a valve, said filler port arrangement further including a stop member in the port opening arranged to enter said elongated nozzle when the latter is inserted into the port opening, thereby opening the valve and allowing magnetic powder to pass into the receptacle from said container.

8. The system according to claim 7 further including trigger means coupled to and controlling said magnetic means, said trigger means being positioned substantially at the edge of the port opening to be operative with a port opening cover of cooperating design, and causing said magnetic means to be automatically actuated whenever the port opening cover is removed.

9. The system according to claim 8 wherein the nozzle of said portable filling container is of high-permutability magnetic material for permitting substantially unhindered flow of the magnetic powder into the receptacle, with the nozzle substantially fully inserted into the filler port arrangement, whenever said magnetic means are actuated.

10. The system according to claim 8 wherein said filler port arrangement and said portable filling container are cooperatively constructed such that insertion of said portable filling container into the port opening automatically switches off said magnetic means in simulation of a cover for the port opening, said magnetic means being reactuated when said container is withdrawn.