Device for checking the porosity of thin rubber products

Proposed is a device for testing the porosity of dielectric foil, particularly rubber products, such as condoms (2) with a cover holder over which the rubber product is placed, and of one or more outer electrodes (5), whereby the cover holder (1) and the outer electrodes (5) are connected to a source of voltage and an electrical gauge, whereby the outer electrodes (5) are in the form of points and the outer electrodes (5) and the cover holder (1) are relatively moveable toward one another so that the skin of the rubber product can gradually be scanned by the outer electrodes (5), and the gauge measures the flow of current in each electrode and by this measurement corresponds to the electrode in a reference measurement for the state in which there is an absence of material without the application of a rubber product, thereby showing a defect.

BACKGROUND OF THE INVENTION 
1. Technical Field of the Invention 
The invention concerns a device for checking the porosity of dielectric 
foils, particularly rubber products, such as condoms and protective gloves 
with a cover holder that is made of durable, electrically conductive 
material and over which the rubber product is placed, and of one or more 
outer electrodes that are on the side of the skin of the rubber product 
opposite the cover holder, whereby the cover holder and the outer 
electrodes are connected to a source of voltage and to an electrical gauge 
via electrical currents. 
Other than for reasons of contraception, condoms are being increasingly 
regarded as protective devices against sexually transmitted diseases, 
particularly the virus that causes AIDS. Therefore, given the necessity of 
their impermeability for the essentially smaller viruses as compared to 
bacteria, the demand for condoms has inevitably risen. It is, however, a 
fact that latex, which is used to manufacture condoms, has shown in a 
number of cases such an evidence of pores that viruses are able to 
penetrate. The reason for this is that latex is constructed from 
interwoven macromolecules, thereby causing the manifestation of selective 
pores as well as a jagged surface with variable durability in the walls. 
The formation of porosity will never occur when other materials such as 
polyurethan are used. Nevertheless, the user is at a disadvantage here 
since polyurethan is plastic and therefore prevents the user from 
achieving the genuine feeling that he desires. 
Given the fact that through the process of manufacturing condoms the 
impermeability of viruses cannot be guaranteed, testing each individual 
condom after manufacture is of great importance. Studies have shown that 
approximately 60% of condoms are virus-preventive. The remaining 40% 
percent, however, contains porous areas through which viruses can 
penetrate. Therefore, condoms do not offer 100% protection from infection. 
Doctors are well aware of this problem and consequently always use two 
pairs of gloves while operating in case they come into contact with blood. 
In this way, any areas on the gloves that may have pores can be physically 
separated from one another so as to essentially reduce the possibility of 
infection. 
2. Description of the Prior Art 
Existing procedures for testing the porosity of condoms consist in placing 
the condom on a metal cover holder and by means of an outer electrode 
measuring the condom's electrical resistance. Consequently, the condom is 
placed with a known device in a conductive fluid, whereby the outer 
electrode acts as the wall of the fluid bath. The disadvantages of this 
procedure are first that the condom must be dried immediately afterward 
and second that the entire surface must be integrally measured, which does 
not allow the individual pores to be localized. 
In another procedure the outer electrode is a metal screen which is placed 
under high voltage, whereby the occurrence of disruptive discharges is 
measured. This procedure, however, is not foolproof given that the latex 
is selectively destroyed by the sparks emitted by the disruptive charges. 
Furthermore, the formation of ozone acts as a disadvantage. 
Consequently, the purpose of the invention is to develop a device for 
testing the porosity of condoms in such a way that individual pores can be 
determined and localized within a diameter of 25 to 75 nanometers. 
SUMMARY OF THE INVENTION 
The invention will carry out its task based on the following data: the 
outer electrodes are in the form of points; the outer electrodes and the 
cover holder are relatively moveable toward one another so that the skin 
of the rubber product is gradually scanned by the outer electrodes; the 
current produced from the source of voltage between the cover holder and 
the outer electrodes is an alternating current or pulsating direct 
current; the gauge measures the flow of current in each electrode and by 
this measurement corresponds to the electrode in a reference measurement 
for the state in which there is an absence of material without the 
application of a rubber product, thereby showing a defect. 
The fundamental reasoning behind the invention is that point electrodes, 
not an extensive outer electrode, will be used to carry out the task. 
Since each individual electrode is utilized according to measurement 
technology, it is possible to detect, show and localize individual pores. 
In order to test the entire surface of a condom, the entire surface is 
scanned by the outer electrodes, meaning that each point of the surface of 
the condom must have at least once during the process of measurement 
fallen short of a definite maximal distance dependent on the measurement 
parameters to one of the electrodes. An alternating voltage lies between 
the outer electrodes and the cover holder: given the capacity between the 
outer electrodes and the cover holder this results in an alternating 
current which is measured separately for each outer electrode. Since latex 
has a dielectric number relatively different from air, areas where no 
latex is present show another capacity than areas with a latex coating. 
The measurement procedure is so sensitive that pores having a size of 10 
muon meters result in such a change in capacity that this change is 
ascertained by the measuring device through the recording of the flow of 
current. If the evaluation of the individual currents of the outer 
electrodes reveals a defect, then this will be indicated on the measuring 
device. In fact, results are obtained during the gradual process of 
measurement based upon the existence of pores of greater or smaller 
diameters in comparison, to the individual measuring points in for 
instance continuous transitions. By official verification the 
corresponding diameters of the pores can be assigned. By indicating a 
threshold value all the pores above the minimal diameter indicated by the 
threshold value can be recorded and shown. By means of scanning the entire 
surface is recorded; by maintaining a constant distance of electrodes the 
measurements can immediately be compared with one another. Otherwise, a 
conversion to standardization must result. 
The overall advantages of the invention are that individual pores can be 
detected and that the measurement is foolproof. 
Given the high voltage involved it is recommended for reasons of safety 
that either a cover holder or the outer electrodes be used. 
Scanning the condom can be particularly effective if the cover holder is 
turned around its rotation axis, the result being that the outer 
electrodes do not revolve tediously around the cover holder but remain 
steadfast. 
The measurement procedure is made even easier if the outer electrodes are 
concentrated in an electrode holder so that they can be moved 
simultaneously by a drive. 
One preference regarding the arrangement of the outer electrodes on the 
electrode support is that the outer electrodes be arranged side by side 
along a straight line, whereby neighboring outer electrodes show a 
constant distance. The advantage here is that large areas can be scanned 
very quickly. 
Another aspect of the invention involves setting several rows alongside one 
another so that the respective gaps of the rows of electrodes are 
recorded. By moving this kind of electrode holder perpendicularly, whereby 
the rows can run their course relative to the condom, the coated areas can 
be measured on the surface. 
As an advantage the rows run parallel to the rotation axis of the cover 
holder. The reason here is that because of the turning of the cover holder 
it is not effective for the outer electrodes to run ring-like around the 
condom. Because of the turning itself all the points located on the ring 
affected by the outer electrode can be reached. 
As a rule it is sufficient to set two rows of outer electrodes halfway at 
the electrode distance in order to facillitate a measurement on the 
surface. 
In addition, by rotating the cover holder it is possible to move the 
electrode holder parallel to the rotation axis of the rover holder up and 
down so that the number of points coated by the outer electrodes can be 
increased. 
Moving the lift of the electrode holder by means of curve gears can prove 
itself an advantage. 
In order to lessen the build up of ozone, which inevitably forms with the 
application of high voltage, a protective gas, particularly nitrogen, is 
conducted between the outer electrodes and the surface of the condom. This 
is another aspect of the invention. This supplying of protective gas can 
be integrated into the electrode holder. 
Technically speaking, the destructive effect of the sparks emitted by the 
disruptive charges has already been explained. In order to suppress this, 
it is recommended that an electrical isolator pointed toward the rubber 
product and the cover holder be fastened. One of the preferred materials 
here is aluminum oxide (Alo).

DETAILED DESCRIPTION OF THE DRAWING AND PREFERRED EMBODIMENTS 
Shown in FIG. 1 is a cover holder (1) that is rotation symmetrical, 
essentially cylindrical and ending in a rounded head. A condom (2) is 
unrolled on the cover holder. At the opposite end of the rounded head of 
the cover holder (1) we see the cover holder connected to a rotation drive 
(3). Directly on the rounded head of the cover holder (1) there is a 
corresponding small, rounded electrode holder (4a) in a row of outer 
electrodes (5) on the side of the condom opposite the cover holder (1). 
The section of the head is covered to the straight, cylindrical part of 
the cover holder (1) by a middle electrode holder (4b), whose outer 
electrodes (5) are lined up along a straight side of the head to the 
beginning of the straight part of the cover holder. Finally, the straight, 
cylindrical part of the cover holder (1) is scanned by a large electrode 
holder (4c), whose outer electrodes (5) are on a straight line parallel to 
the rotation axis of the cover holder (1). All the electrode holders (4a, 
4b, 4c) are connected to curve gears (6), moving up and down along the 
rows of outer electrodes (5). Each outer electrode (5) is connected to a 
measuring device via an electrical current (7). (This is not depicted). 
FIG. 2 shows a part of one of the three electrode holders (4a, 4b, 4c). The 
outer electrode (5) itself is a plate that is on the surface of the 
electrode holder (4a, 4b, 4c). The plate is connected to an electrical 
current (7), which is led through a bore-hole (8) through the electrode 
holder (4a, 4b, 4c) to the opposite side and then to the measuring device 
(not depicted). At a distance from the outer electrode (5) the condom is 
rolled (2) over the cover holder (1). 
In FIG. 3 an unrolled condom (2) over the cover holder (1) is greatly 
enlarged. The condom (2) is also interwoven and constructed from split 
macromolecules, showing a relatively large pore (10) in one place. Outer 
electrodes (5) are arranged over the condom at an equal distance. The 
electric field, which is relatively inhomogenous because of the pore (10) 
and stands between the outer electrodes (5) and the cover holder (1), is 
indicated by field lines.