JPH0337933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a static elimination brush for fingerprint collection, which is used, for example, to collect fingerprints left at a crime scene.

(b) Prior Art FIG. 4 is a perspective view showing a conventional fingerprint collecting brush.

The conventional fingerprint collecting brush 9 has a brush part 92 formed at the tip of a rod-shaped handle part 91 having a certain length, and this brush part 92 is made of a large number of non-conductive fiber materials 93.
It consists of A large number of non-conductive fiber materials 93
For example, a non-conductive thread-like material such as animal fiber hair or synthetic fiber is used.
It is attached to the tip of.

To collect fingerprints, various kinds of fingerprint collecting agents are used depending on the member to which the fingerprints are attached. Fine powder of aluminum oxide is usually used as a fingerprint collecting agent, but in addition to this, powders of antimony, graphite, guangmingan, stone pine, eosin, fuchsin, etc. can also be used. When collecting fingerprints, at the crime scene, apply the fingerprint collecting agent (fine alumina powder) that you brought with you to the tip of the brush for fingerprint collection, and this is where the fingerprints will likely be attached. Components (glass surfaces, ceramic surfaces, metal utensils, hard paper, painted walls, etc.)
Apply fine alumina powder to the surface. As a result, a white fingerprint (ridges forming a fingerprint to which finger fat is attached) appears on the surface of the member. The revealed fingerprint is transferred to a transparent adhesive tape (or gelatin paper) and collected.

(c) Problems to be solved by the invention When a person taking fingerprints goes to a crime scene, he or she carries a medicine for collecting fingerprints. At this time, the collection agent (fine alumina powder) housed in the case becomes electrically charged due to friction and other factors due to vibrations when carrying the device. For this reason, when alumina fine powder charged with static electricity is attached to the brush part of a fingerprint collecting brush and applied onto a fingerprint, there is a disadvantage that a clear fingerprint cannot be taken due to the influence of static electricity. For example, electrostatically charged powder strongly adsorbs to the bristles of the brush area.
A clear fingerprint may not be revealed if the fingerprint is not properly drawn or depending on the electrical characteristics of the material surface of the member (for example, a metal knob) to which the fingerprint is attached. As an example of this, if the surface of a component on which a fingerprint is attached is charged with the same electricity (positive electricity or negative electricity) as the static electricity charged on the powder, the powder may not be in the proper state on the fingerprint due to electrical repulsion. I can't hold back. Or, conversely, if the surface of the component on which the fingerprint is attached is charged with an electric charge that is different from the static electricity charged on the powder, the powder will be strongly attracted to the grooves between the ridges that form the fingerprint due to electrical attraction. There were disadvantages such as the boundaries of the ridges were not clear and clear fingerprints could not be revealed.

This invention solves the above-mentioned problems and provides a static electricity removal brush for fingerprint collection that can always collect clear fingerprints by actively eliminating static electricity from the fingerprint collection agent (fine alumina powder). purpose.

(d) Means and operation for solving the problem In order to achieve this object, the static elimination brush for fingerprint collection of the present invention has the following configuration.

The static elimination brush for fingerprint collection is a brush equipped with a brush part at the tip of the handle, and the brush part is made by dispersing a large number of conductive fiber materials mixed with a large number of non-conductive fiber materials. This conductive fiber material is constructed by forming a conductive film on the surface of acrylic fibers to which monovalent copper ions are adsorbed.

In the static elimination brush for fingerprint collection having such a configuration, by dispersing and distributing short conductive fiber materials in a mixed manner with respect to relatively long non-conductive fiber materials,
It forms the brush part. In other words, the tip of the conductive fiber material is set in a state where it is retracted toward the handle portion with respect to the non-conductive fiber material. When taking fingerprints,
As in the past, a fingerprint collecting agent (fine alumina powder) is bonded and adhered to the tip of the brush part. In other words, fine alumina powder adheres to the tip of the long non-conductive fiber material. At this time, the tip of the short conductive fiber material
It approaches the electrostatically charged alumina powder, and uses a weak discharge phenomenon called corona discharge to remove the static electricity from the alumina powder. The conductive fiber material is composed of an acrylic fiber on which monovalent copper ions are adsorbed, and a conductive film is applied to the surface of the acrylic fiber. This conductive film is a copper sulfide-like film obtained by heat-treating acrylic fibers on which monovalent copper ions have been adsorbed with a reducing aqueous solution containing, for example, a hydrosulfite substance. In other words, it is a metallic composite conductive layer. The conductive fiber material is made of thread-like fibers (that is, metal-containing organic conductive fibers made of an acrylonitrile-copper sulfide composite). Therefore, when such a brush part (conductive fiber material) is brought close to electrostatically charged powder, a corona discharge phenomenon occurs through the insulator (air) between the brush part and the conductive fiber material, and the powder is Static electricity charged in the body is discharged. This is because the conductive film (copper sulfide film) on the surface of the conductive fiber material, that is, the acrylic fiber, has a rough surface with microscopic irregularities. Therefore, the electrostatically charged powder and the conductive fiber material can be regarded as a pair of electrically opposing electrodes. The conductive fiber surface (conductive film) between these two electrodes has an uneven surface, so there is variation in the distance between the two electrodes, and the electric field strength between the two electrodes is also different, resulting in an inhomogeneous electric field (unequal electric field). becomes. Therefore, before spark discharge occurs between the two electrodes, a weak discharge phenomenon called corona discharge occurs. In other words, the insulation of the air interposed between the two electrodes is destroyed, and the static electricity of the powder is discharged.
Therefore, the static electricity charged on the powder can be positively eliminated by the usual operation of simply bringing the brushing part of the brush into contact with and away from the powder. In this way, clear fingerprints can always be collected.

(E) Embodiment FIG. 1 is a perspective view showing a specific embodiment of the static elimination brush for fingerprint collection according to the present invention.

As is well known, the static elimination brush 1 for collecting fingerprints is composed of a handle part 2 and a brush part 3 formed at the tip of the handle part 2.

The handle portion 2 is made of, for example, synthetic resin or wood, and is shaped like a round bar with a certain length. A feature of the present invention is that the brush portion 3 is formed by distributing a large number of conductive fiber materials 5 mixed with a large number of non-conductive fiber materials 4 in a dispersed manner. The non-conductive fiber material 4 is made of a non-conductive material such as animal fiber (for example, "squirrel" hair) or synthetic fiber thread, and is set to be relatively long. The conductive fiber material 5, which is a feature of the present invention, is set short in the embodiment as shown in FIG. Each base end is fixed to the tip of the handle portion 2 via a metal fitting 6.

The above-mentioned conductive fiber material 5 allows monovalent copper ions to be adsorbed to the acrylic fiber. In other words, the nitrile groups (CN groups) in the acrylic fibers and copper ions are ionically bonded. The acrylic fibers that have adsorbed copper ions are then heat-treated with a reducing aqueous solution.
As the reducing aqueous solution, for example, a hydrosulfite substance (for example, sodium hydrosulfite (NaSO ₄ )) is used. As a result, an extremely thin conductive film 51 is formed on the fiber surface. is a copper sulfide-like film. In other words, it is a metallic composite conductive layer. It is constructed by spinning organic conductive fibers into a thread.

When performing fingerprint collection work using the static elimination brush for fingerprint collection having such a configuration, assuming that the fingerprint collection agent (fine alumina powder) 7 is electrostatically charged, use the brush as in the conventional case. The tip of the brush part 3 of No. 1 is joined to and adhered to the electrostatically charged alumina powder 7. That is, the fine alumina powder 7 is attached to the tip of the elongated non-conductive fiber material 4 . At this time, the tip of the short conductive fiber material 5
It approaches the electrostatically charged alumina powder 7 and eliminates the static electricity charged on the alumina powder 7 by a weak discharge phenomenon called corona discharge. This is because the surface of the conductive film (metallic copper sulfide film) 51 on the surface of the acrylic fiber constituting the conductive fiber material (acrylonitrile-copper sulfide composite) 5 is microscopically uneven and rough. There is. Therefore, the electrostatically charged powder 7 and the conductive fiber material 5 can be regarded as a pair of electrodes that are electrically opposed to each other. Between the two electrodes (the electrostatically charged powder 7 and the conductive fiber material 5 having a metallic composite conductive layer), the surface of the conductive fiber material (the conductive film 51) is uneven and rough. 5,
There is variation in the distance between electrodes 5 and 7, and the electric field strength between both electrodes 5 and 7 is different, resulting in a non-uniform electric field (unequal electric field).
becomes. Therefore, before a spark discharge occurs between the electrodes 5 and 7 (between the conductive fiber material 5, which does not have a high charge, and the powder 7, which has a high charge), a weak discharge phenomenon called corona discharge occurs. . In other words, the insulation of the air interposed between both electrodes 5 and 7 collapses, and the powder 7
static electricity is discharged into the air. Therefore, the static electricity charged on the powder 7 can be eliminated by simply bringing the brush portion 3 of the brush 1 into contact with and away from the powder 7 as usual. In this way, the powder 7 is attached to the non-conductive fiber material 4 of the brush part 3, and as shown in FIG. The fingerprint 8a can be revealed.

Moreover, the brush part 3 provided with this conductive fiber material 5
can prevent itself from being charged, so the brush part 3
Since the static electricity that may be generated when rubbing the brush against the surface of the fingerprint attachment member 8 is eliminated, there is no risk of impurities such as dirt and dust adhering to the brush part 3, and even clearer fingerprint collection can be achieved. . Further, since the conductive fiber material 5 is made by subjecting acrylic fibers to which monovalent copper ions have been adsorbed to a ring-forming treatment to form the metallic conductive film 51, the conductive fiber material 5 is resistant to washing liquids and is resistant to brushing portions 3.
does not lose its static eliminating effect even after washing.

In addition, when carrying out the operation, as shown in FIG. 1 or 2, a discharge cord 52 made of the same material as the conductive fiber material 5 is connected to the base end of the conductive fiber material 5, It may be arranged in a drawer shape outward from the metal fitting 6. By deploying this discharge string 52,
Even if charges higher than corona discharge occur continuously, static electricity can be effectively eliminated.
Further, in actual implementation, conductive printing may be applied to the surface of the handle portion 2 using conductive ink, and in this case, the earthing effect can be further enhanced.

(f) Effects of the Invention In this invention, as described above, a large number of conductive fiber materials made of acrylic fibers on which monovalent copper ions have been adsorbed are mixed in a dispersed state with a large number of non-conductive fiber materials. Since it was decided to deploy the brush part to form the brush part, it is possible to deal with the fingerprint collection medicine (powder) that is charged due to vibration friction etc. during carrying, under the normal operation of bringing the brush part into contact with and separating it from the collection medicine. The static electricity charged on the powder can be positively removed by the corona discharge phenomenon.

Therefore, the disadvantages of conventional fingerprint collecting agents, such as not being able to collect clear fingerprints due to the influence of static electricity, are eliminated, and regardless of the electrical characteristics of the parts on which fingerprints are attached, It has excellent effects that achieve the purpose of the invention, such as being able to take clear fingerprints.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the static elimination brush for fingerprint collection according to the embodiment, FIG. 2 is an enlarged explanatory view of the main part showing the brush part of the static elimination brush for fingerprint collection according to the example, and FIG. 3 is a perspective view showing the static elimination brush for fingerprint collection according to the embodiment. FIG. 4, which is an explanatory diagram showing a state in which a fingerprint is collected with a static eliminating brush, is a perspective view showing a conventional fingerprint collecting brush. 1: Brush body, 2: Handle part, 3: Brush part,
4: Non-conductive fiber material, 5: Conductive fiber material, 51:
conductive film.

Claims (1)

[Claims] 1. A brush equipped with a brush part at the tip of the handle part, where the brush part is made by distributing a large number of conductive fiber materials mixed with a large number of non-conductive fiber materials,
This static eliminator brush for fingerprint collection is characterized in that the conductive fiber material is formed by forming a conductive film on the surface of acrylic fibers that have monovalent copper ions adsorbed.