Abstract:
A hypodermic syringe needle detector consisting of a normally open circuit adapted to be closed when a hypodermic syringe needle penetrates the device and simultaneously makes electrical contact between two or more elctrically conductive surfaces. Closing the circuit energizes a sensory alarm such as an audio signal or light.

Description:
BACKGROUND OF THE INVENTION 1. Field of the Invention 
     This invention relates in general to warning alarms and in particular to warning alarms which detect the presence of hypodermic syringe needles. 
     2. Prior Art 
     Fear of puncture by a contaminated hypodermic syringe needle is common among health care workers, police officers and others who may come into contact with contaminated needles. In the past, protection has relied upon the use of protective clothing. No device is known, however, which can be used by police officers or others to search in pockets or similar areas for needles and which will raise an alarm if a needle is detected. The objective of the present invention is to provide a warning device which will warn of potential exposure to contaminated needles so that appropriate measures may be taken to avoid contamination from needles. 
     SUMMARY OF THE INVENTION 
     As stated above the primary objective of the invention is to warn of the presence of needles in areas where visual inspection is difficult. This invention is a device to detect metal needles by using the ability of the metal needle to conduct electricity and complete an electric circuit which will then trigger an alarm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cutaway drawing of a needle detection device in accordance with the present invention. 
     FIG. 2 is a side perspective of the device of FIG. 1. 
     FIG. 3 is an enlarged, fragmentary cross-section of the external detection layer of said device. 
     FIG. 4 demonstrates in general terms the circuitry of a needle detection device in accordance with the present invention. 
     FIG. 5 is a top view of a needle detection device in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION 
     As shown in the drawings, the preferred hypodermic syringe needle detection alarm device in accordance with the present invention includes a portable case of cylindrical shape which preferably is of strong molded plastic material. The case is hollow so that it can contain the power source and other working parts. At the bottom end of the device attached to the outside of the case is the external detection layer, more particularly described in FIG. 3. 
     In detail the case 1d has at its top a preferably direct current lamp la and is connected to said lamp at 4a2 and 4a1 by preferably metal wire 4b &amp; 4c. Continuing down the case is shown on/off switch 1h, relay 1b, power source 1c, power source terminals 1f &amp; 1g and external detection circuit 1e. 
     The circuitry is more particularly described in FIG. 4. Lamp 4a is connected at terminal 4a2 to preferably wire 4c which in turn connects to power source terminal 4q. Said lamp is also connected at terminal 4a1 to preferably wire 4b which in turn connects to relay terminal 4f. Terminal 4f is connected to terminal 4q by moving pole 4fg. Space 4gi represents air space which is evident when the on/off switch 4m is in the off position or when the on/off switch is in the on position but there is no electrical connection between the conductive layers shown in FIG. 3 as 3b and 3d (under normal operating conditions when the power source is fully operable) but terminals 4g and 4i will be in electrical contact when the electromagnet portion of the relay 4h is activated. Preferably wire connection 4k extends from relay terminal 4i to power source terminal 4s. 
     Preferably wire 4t connects terminal 4s to external detection layer 4B, more precisely said wire connects at a point 3b1 as indicated in FIG. 3. Preferably wire 4v connects at point 3d1 (layer 4D) and runs to point 4p which is one terminal of the electromagnet portion of the relay. Terminal 4o is the other terminal of the electromagnet and connects to power source terminal 4Q by preferably wire connection 4y. Preferably wire connects from point 4p to relay terminal 4w via said wire 4d. Terminal 4w connects to terminal 4h of the relay via moving pole 4wh. Space 4hj represents air space which is evident when the on/off switch is in the off position or when the on/off switch is in the on position but there is no electrical connection between said conductive layers (under normal operating conditions) but under normal operating conditions when the power source is fully operable terminals 4h &amp; 4j will be in electrical contact when the electromagnet portion of said relay is activated. Preferably wire 41 connects terminal 4j with power source terminal 4s. Preferably wire connection 4t extends from power source terminal 4s to detection layer terminal 3b1 through point 1h which is an opening in the case 1d. Preferably wire connection 4v extends from detection layer terminal 3d1 through point 1i which is an opening in the case 1d. 
     Inside the case and inserted in a straight line in the preferred version lie four AA size flashlight batteries of approximately 1.5 volts DC each which serve as the power source for the device. In the preferred version all electronic parts operate on six volts DC, said voltage being approximate. 
     Referring now to FIGS. 1 through 4 which are overall drawings of a preferred embodiment of the invention, the figures represent a portable, handheld, dry cell battery powered device which emits an alarm in the form of light (alternatively sound also) when in normal operation the external detection layers are pierced by an electrically conductive hypodermic syringe needle. A case of molded plastic serves as the container for the working parts and also as a base upon which the external detection layers, which comprise two conductive metal foil layers separated by a non-electrically conductive insulative material, preferably common plastic stretch wrap for the insulator between the two conductive layers and common aluminum foil for the two conductive layers. Attached to the bottom end of the case by preferably common cyanoacrylate adhesive is the base layer, which preferably is of cork in a thin layer, an alternative being rubber in a thin layer, such layer being preferably about 1.5 to 2 millimeters in thickness, covering the bottom preferably 100 approx. millimeters of the cylindrical case. The cylindrical case should preferably be at least about 15 millimeters in inside diameter in order to accommodate the AA batteries(alternatively smaller or larger batteries could be used, with appropriate adjustment in the inside diameter of the case). The total length of the case should preferably be about 300 millimeters and approx. 50 millimeters from the top (the top being where the lamp is located) the outside diameter should flare to about 40 to 50 millimeters so that said portion may serve as a convenient object for a handhold on the device while in use. Regarding the outside diameter of the case below said top portion such outside diameter should not exceed about 20 millimeters so that the device will more easily fit inside pockets. Regarding the second layer which preferably covers about the bottom 100 millimeters (all external detection layers cover about the bottom 100 millimeters of the case) and is attached to the base layer preferably by common cyanoacrylate adhesive, this layer of preferably common aluminum foil would preferably comprise two layers of said foil and would total about 0.1 millimeter in width, preferably these two foil layers which collectively comprise one foil conductive layer of the device should be held in proximity by friction from the immediately above and below layers. Alternatively a greater number of individual metal foil layers could be used to comprise the said conductive layer (or a single foil layer could be used). Surrounding the foil layer lies a non-electrically conducting layer comprising preferably about 2 layers of common plastic stretch wrap forming collectively a single insulative layer between the conductive layer mentioned above and the conductive layer described below in order that no electrical contact occurs between said two conductive layers unless an electrically conductive object pierces the outside conductive layer and continues on to make electrical contact with the inside conductive layer in such a fashion that electrical contact is simultaneously made between both said conductive layers. 
     An electrical terminal located on the inside conductive layer provides electrical connection with the power source via preferably metal wire as shown in the figures presented. A second electrically conductive layer constructed preferably identically to the abovementioned conductive layer rests on the insulative layer, with an electrical terminal attached preferably as shown in the figures to provide electrical contact via preferably metal wire with the remainder of the circuitry of the device. The second conductive layer (outside layer) is covered by a flexible porous, about 5 millimeters width flexible material, preferably sponge type plastic, alternatively about four layers of common plastic stretch wrap may be used for this layer which is the outside protective layer of the external detection layers. Preferably all said layers cover about the bottom 100 millimeters of the case in order to provide sufficient contact area for the device to contact hypodermic syringe needles when in use. 
     In the preferred embodiment, the two terminals at either end of the power source are metal coils which in use will be partially compressed by the batteries when said batteries are in place in order to provide good electrical contact between the power source and said terminals, and suitable terminals will attach to said coils for attachment of all wires as shown in the figures. The preferable version will also have an on/off switch which for simplicity was not included in the FIG. 4 circuit drawings but the preferred version in use will have one terminal at 4s which will connect electrically to metal wire, the other end of said wire being connected to one terminal of the on/off switch (said on/off switch having two terminals) connected to the second terminal of said on/off switch will be a metal wire which will electrically contact the positive pole of the power source at a point between said pole and terminal 4s in such a fashion that electricity does not flow from the positive pole of said power source to point 4s unless said on/off switch is on the &#34;on&#34; position. 
     In the preferred version the external protective layers will be removable and replaceable when worn. In use, by way of example and not limitation, the bottom portion of the device will be inserted into the pockets of a suspect in police custody who is being searched. The bottom end of the device would be manipulated around the inside of the pocket in such a manner that if an exposed hypodermic syringe needle is in the pocket, said needle will penetrate the outer protective layer, the outside conductive layer, the insulative layer, and then make electrical contact with the inside conductive layer which, by making electrical contact between the two said conductive layers, complete an electrical circuit and trigger the alarm, the relay locking in such a manner that the alarm will continue to emit warning until the on/off switch is turned to the &#34;off&#34; position even if electrical connection is lost between the two said conductive layers. The alarm will alert the searching officer. 
     Alternatives, by way of example and not limitation, can include a buzzer or other sound device as well as a lamp or light emitting diode for the alarm warning, different power sources or voltages could be used, and different types of conductors or insulators could be used, as well as different materials for the case. Different types of relays could also be used. 
     While preferred embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims. 
     The base layer of the device is preferably an insulator and is bonded to the case, then covered by a second layer of electrically conductive material, which is then covered by an electrically non-conductive material which is sufficiently permeable to permit the passage through it of a hypodermic syringe needle, said layer also being covered by a conductive layer which is also sufficiently permeable to permit the passage through it of a hypodermic syringe needle. This last mentioned layer is also covered by another layer which is sufficiently permeable to permit the passage through it of a hypodermic syringe needle. Said conductive layers are attached to said power source and said electromagnet in the manner shown in the drawings and in such a manner that when there is electrical connection between said two conductive layers said electromagnet is supplied with power and said electromagnet moves the moving poles of said switch in such a manner that said moving poles move to make electrical contact with those terminals which, in the absence of said power to said electromagnet, are separated from said moving poles by airspace. No electrical connection is present between the two conductive layers unless a conductive material such as a needle simultaneously makes electrical contact with both such conductive layers, said space between said two conductive layers being the only point of opening in said detection circuit which includes as part of said circuit said external detection layers, as demonstrated in the drawings. 
     As shown in the drawings, the detection circuit drives an electromagnet when electrical contact is made with both said conductive layers at the same time. Said electromagnet is connected to said switch in such a manner that when said electromagnet is driven the moving poles make contact with the switch terminals which close the circuits which drive the alarm and which lock the electromagnet into a driven state thus locking the alarm on. In the absence of any initial electrical contact between said conductive layers, the electromagnet will not be driven, however once the electrical contact between said conductive layers is made, the switch, which acts as a relay, will lock the alarm into a warning alert state.