GB2059347A

GB2059347A - Brush for dusting fingerprints

Info

Publication number: GB2059347A
Application number: GB7934029A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-10-01
Filing date: 1979-10-01
Publication date: 1981-04-23
Also published as: GB2059347B

Abstract

A magnetic fingerprint dusting brush has a tubular handle 10 with a magnet 14 which extends from one end or a magnetised end. A cartridge 16 is push fitted onto the magnet or end and includes an inner blind sleeve 18 which extends coaxially from an inner cylindrical sleeve 20 of larger diameter. The section 18 receives the magnet 14 or end and section 20 the lower end of the handle 10 when the cartridge is fitted in place on the handle. The cap contains ferrous powder particles 26 which align to form a bristle like array 28. Black carbon particles are mixed with the ferrous particles. Removing the cap 24 exposes the loaded bristles. After use the cap 24 can be screwed onto the sleeve and the cartridge removed. A frusto-conical guard may be provided to prevent powder particles entering the screw threaded section. <IMAGE>

Description

SPECIFICATION Improvements in and relating to brushes for dusting fingerprints Field of invention This invention concerns brushes for dusting surfaces believed to bear fingerprints, hereinafter referred to as magnetic fingerprint dusting brushes.

Background to the invention Magnetic fingerprint dusting brushes have been used for some time by various police forces in the process of dusting for fingerprinting at the scene of crime.

The brush consists of a handle similar to the handle of a conventional artist's brush. Instead of the bristles there is a small cylindrical permanent magnet. In use the magnet is dipped into a jar of ferrous powder which is mixed with a quantity of powered carbon or the like. The ferrous powder clings to the magnet along the lines of force of the magnetic field and forms a bristle-like array which serves as a carrier for the carbon powder. The magnetic brush is then used in place of a conventional brush to locate and identify latent fingerprints, the carbon powder transferring from the aligned ferrous powder particles to the print area.

The loading of such a 'magnetic brush' and the subsequent unloading after use can be a messy procedure. Some proprietary magnetic brushes have a retractable magnet within a non-ferrous blind sleeve, so that when the magnet is retracted the ferrous powder can be made to drop off for example into the jar. However a residue of carbon powder often remains on the sleeve so that it still has to be cleaned properly before it can be stored for example in the operator's pocket.

Object of the invention It is an object of the present invention to provide an improved magnetic fingerprint dusting brush which inter alia overcomes the aforementioned problems of loading and unloading.

The invention According to the present invention a magnetic fingerprint dusting brush comprises - a handle which is magnetised at least at one end or includes a magnet at one end thereof, - a non-magnetic shroud adapted to be secured to the magnet or the magnetic end of the handle, - a cover detachably secured to the shroud and forming when secured on the shroud an enclosed power reservoir, and - a mixture of ferrous and dusting powder in the reservoir, the ferrous powder aligning along the lines of the magnetic field of the magnet to form the known magnetic bristles when the magnet or magnetised end of the handle is inserted in the shroud.

Typically the handle is like a pen and a small cylindrical magnet is fitted into the end in place of the nib. The shroud is likewise cylindrical and is adapted to be push-fitted over the magnet so that it can be easily pushed into place or removed. Conve nientlythe shroud includes an inner cylindrical sleeve closed at its lower end which is the part into which the magnet/handle fits and a second cylindrical sleeve, of somewhat larger diameter, extends around the inner sleeve to form an annular reservoir, the lower end being open and the upper end closed, and the cover is in the form of a closed cylindrical cap similar to the inner sleeve portion of the shroud and adapted to be secured thereto.

The inner sleeve extends axially beyond the outer sleeve so that when the cap is removed, it is exposed like a pen-nib.

Although the inner sleeve is formed from nonmagnetic material such as a plastics material, it assumes the properties of a magnet when the magnet or magnetic end of the handle is inserted therein. Consequently, magnetic particles contained in the reservoir will cling to the outer surface of the inner sleeve in the same way as if it were a magnet to form magnetic bristles in the aforementioned manner.

One advantage of the invention is that the shroud and detachable cover/cap can be formed entirely from non-magnetic material (and are preferably so formed to create a non-magnetic cartridge) and the mixture of magnetisable ferrous powder and dusting powder can be loaded into and unloaded from the cartridge with the cartridge separate from the handle, and the effect of the magnetic field associated therewith.

Another even more important advantage of the invention is that the permanent magnet need never come into contact with the powder so that the magnet remains clean at all times. Thus after use the cover/cap can be replaced and the cartridge removed from the handle and the latter can be put directly into the pocket without any need for cleaning. To this end the handle conveniently includes a pocket clip or the like.

A further advantage of the invention is that a number of separate cartridges can be used by an operator, containing different powder mixtures for different types of fingerprint detection, and there is no need for elaborate cleaning procedures when the operator wishes to change from using one type of powder mixture to another.

A non-magnetic cover may be provided for fitting over the magnet or magnetic handle and when no cartridge is in position.

Further advantages of the invention are: - no risk of spillage due to open powder containers, - no problems associated with trying to get correct amount of powder on brush - a measured amount of powder mixture can be pre-loaded in each cartridge, -no messy residues remain on handle after use brush handle never comes into contact with powder, - 'dilution' of the powder is minimized. In conventional systems the powder is continually used so that the carbon powder is gradually used up, so that the efficiency deteriorates over a period. By using cartridges as proposed by the invention, the cartridge can be made disposable when the dusting powder content is spent.

The invention will now be described by way of example with reference to the accompanying drawing.

In the drawing Figure 1 is a cross-section through one embodiment of the invntion, Figure 2 shows the magnet withdrawn from the cartridge, and Figure 3 shows the cartridge end of the brush with the cap-cover removed, ready for use.

Detailed description of the illustrated embodiment A plastics tubular barrel or handle 10 includes a pocket clip 12 and, as best shown in Figure 2, a magnet 14 which extends from one end. A cartridge generally identified by reference numeral 126 is fitted to the magnet by a simple push-fit. The cartridge includes an inner blind sleeve 18 which extends coaxially from an inner cylindrical sleeve section 20 of larger diameter. The section 18 receives the magnet 14 and the section 20 the lower end of the handle 10, when the cartridge is fitted in place on the handle.

The upper end of the section 20 is integral with an outer cylindrical sleeve 22 which extends from its upper end by the same axial length on the inner sleeve section 20. A closed cylindrical cap 24 is screwed to the open end of the outer sleeve 22.

When the cap 24 is unscrewed and removed, the inner sleeve section 18 is exposed.

The cap contains a measured quantity of ferrous powder particles 26 (see Figure 2) which, when the magnet 14 is inserted into the sleeve 18, are attracted to the sleeve 18 and align to form a bristle-like array 28 as shown in Figures 1 and 3.

Mixed with the particles 26 are black carbon particles or the like forming a fingerprint dusting powder, which particles are carried by the bristle-like array of ferrous particles in known manner. Removing the cap 24 exposes the loaded "bristles" as shown in Figure 3.

After use the cap 24 can be screwed onto the sleeve 22 and the cartridge 16 can, if required, then be removed from the handle 10.

A further refinement may be provided in the form of a frusto-conical guard 30 at the junction of the sleeve section 18 and the shoulder between it and the larger diameter section 20. This guard serves to prevent powder particles from becoming trapped between the screw threaded section of the cartridge 16 and the cap 24 as the latter is pushed over the bristle-like array 28 after use.

Claims

1. A magnetic fingerprint dusting brush comprising (1) A handle which is magnetised at least at one end or includes a magnet at one end thereof (2) A non-magnetic shroud adapted to be secured to the magnet or the magnetic end of the handle (3) A cover detachably secured to the shroud and forming when secured on the shroud an enclosed power reservoir and (4) A mixture of ferrous and dusting power in the reservoir, the ferrous powder aligning along the lines of the magnetic bristle when the magnet or magnetised end of the handle is inserted in the shroud.

2. A magnetic fingerprint dusting brush as claimed in claim 1 in which the handle is a cylindrical barrel and the magnet is also cylindrical but of smaller diameter and is fitted into one end thereof.

3. A magnetic fingerprint dusting brush as claimed in claim 1 or 2 in which the shroud is cylindrical and is adapted to be push fitted over the magnet so that it can easily be pushed into place or removed.

4. A magnetic fingerprint dusting brush as claimed in claim 3 in which the shroud includes an inner cylindrical sleeve closed as its lower end, the cylindrical sleeve being the part into which the magnet or the handle fits and the shroud comprises a second cylindrical sleeve of larger diameter than the first inner cylindrical sleeve which extends around the inner sleeve to form an annular reservoir, the lower end of the reservoir being open and the upper end closed.

5. A magnetic fingerprint dusting brush as claimed in claim 4 in which the cover is in the form of a closed cylindrical cap which is adapted to be secured to the inner sleeve portion of the shroud.

6. A magnetic fingerprint dusting brush as claimed in claim 5 in which the inner sleeve extends axially beyond the outer sleeve so that when the cap is removed it is exposed.

7. A magnetic fingerprint dusting brush as claimed in any of the preceding claims wherein the shroud and detachable cover or cap are formed entirely from non-magnetisable material.

8. A magnetic fingerprint dusting brush as claimed in any of the preceeding claims further comprising a non-magnetic cover for fitting over the magnet or magnetic handle when no cartridge is in position.

9. A magnetic fingerprint dusting brush constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.