Rotary Screw Switch

Abstract

A flashlight is described having a switch which employs two existing components of conventional flashlights in such a manner as to eliminate a separate thumb switch, but which retains the function of the separate switch. The switch employs the threaded end cap of the flashlight which is tightened to make contact between the barrel of the flashlight and loosened to break the circuit. The tube or barrel of the flashlight serves as one conduit and a spring used to bias the batteries is the other. The circuit is closed by bringing the barrel into contact with a portion of the spring. The switch has other application than to flashlights.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a novel switch and in particular relates to a tubular type flashlight in combination with said novel switch.

Battery operated, portable flashlights are common fixtures in homes, offices, vehicles, emergency kits and other locations. They are a primary and essential tool for numerous occupations and applications, For example, police and security officers rely heavily on their flashlights to deter and detect crime. In almost every use of flashlights, dependability of operation is an absolute essential. An inoperative flashlight defeats the entire purpose, very often, of having cached the light at a particular location. For many purposes the flashlight is in place for an emergency application, and immediate operation is required, even after long periods of inactivity and storage.

There are principally three areas of potential trouble in the ordinary flashlight. The first is ruptured or depleted batteries. The second is a defective bulb, and the third is the switch. The first two problems are readily and quickly corrected, even under emergency or adverse conditions. The third potential problem of the switch, however, presents a malfunction which, when it occurs, usually means the end of the useful life of the flashlight.

Conventional prior flashlight switches are highly susceptible to corrosion which is almost invariably the cause for a flashlight to be discarded. The corrosion is a problem because of the acidic environment which is present as a result of the batteries. It is not uncommon for a minor leak to develop in a battery and for corrosion to develop within the flashlight. The nature of the conventional switch and the tenuous manner in which contact is made are the primary causes for corrosion being a serious problem. Repair or renovation of a badly corroded switch is essentially not possible or not worth the trouble and effort. Furthermore, the very nature of the switch is such that it cannot be repaired in that it is usually not accessible.

It has now been found that a superior flashlight, i.e., superior in durability, service and repairability, can be achieved by elimination of the conventional thumb switch from the flashlight and retention of the function of the switch with only the remaining elements. Moreover, the elimination of the thumb switch has resulted in a flashlight which can be produced at reasonable cost which is practically indestructable even when subjected to repeated sharp, heavy blows with the flashlight.

It is thus an advantage of the present flashlight that an element, i.e., the thumb switch, can be eliminated and the function be retained. It is a further feature of the present invention that a more durable flashlight be provided. Another feature of the present invention is the provision of a flashlight which is far less susceptible to disability from corrosion. A particular advantage of the present invention is that corrosion, should it occur and disable the operation of the flashlight can readily be cleaned away. Another feature of the present invention is a novel and simple switch. Another feature of the present invention is the provision of a flashlight with fewer operating parts than prior flashlights. Yet a further advantage of the present invention is the provision of a flashlight having the advantages and features described and which can be readily produced with existing equipment and by present manufacturers or by small manufacturers using only basic machine shop equipment.

SUMMARY OF THE INVENTION

The present invention, very briefly, lies in a rotary screw-down switch and to said switch in combination with the other elements of a flashlight to form a new flashlight combination. Basically the invention in the switch employs screwing the end cap on the flashlight down to bring the tube of the flashlight in contact with the biasing member, e.g., a coil spring, thus closing the circuit and causing the flashlight to operate. The switch can of course be applied to other devices besides flashlights, and it can be employed with either AC or DC current.

The invention, including the specific embodiment relating to the flashlight, will be clear from the following description of the drawing. The same part or member has been identified with the same designation where possible. There are possible a number of reversal of parts in the present invention that are readily within the ordinary skill in the art to effectuate. The reversals of parts will neither change the function nor the result and are contemplated to be within the scope of this invention as are other obvious and conventional substitutions of known equivalents.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a partial cross section of a battery powered, hand-held flashlight in a combination with the present switch.

FIG. 2 is an isometric view of the end of a tubular member, for example from a flashlight as depicted in FIG. 1.

FIG. 3 is a cross sectional view taken along 2--2 of FIG. 1.

DETAILED DESCRIPTION OF A SPECIFIC EMBODIMENT

Referring to FIG. 1, a flashlight employing the present switch is disclosed. There are a number of conventional and standard items employed in the flashlight, said items performing their art recognized function. There are some items which partially perform their prior art functions but also have new functions according to the invention, and there are a number of entirely new elements not previously related to flashlights. FIG. 1 shows a flashlight having a barrel or tube 1 having threads 8 and 16 at each end of the barrel 1. For the purposes of this description the end of the barrel 1 having threads 8 shall be considered the "upper end" of the barrel 1. Attached to threads 8 on the top of barrel 1 is head 2 which serves as a housing and receptacle for the reflector assembly of the flashlight. The reflector assembly is a completely conventional item employed in a somewhat unconventional manner and is comprised of the reflector 10, contact plate 9, neck 11 and a securing member 12 which is attached to the neck 11 in this instance and has threads and is screwed into the neck 11. The securing member 12 is usually a non-conducting material such as plastic, bakelite, or the like and has a contact 14 which is in contact with the bottom terminal of the bulb and is biased so as to maintain contact with the batteries 29. The contact plate 9 is in electrical contact with the neck which contacts a second terminal of the bulb. Both the neck 11 and the contact plate 9 are comprised of a conductive metal. The contact plate 9 is disk-like and is seated against top edge of barrel 1. The contact plate 9 is held in tight contact with the barrel by lens cap 3 which is screwed onto threads 7 on head 2.

The lens cap 3 clamps down on the lip portion 5 of lens 4 which is seated against the corresponding lip 13 of reflector 10. The head 2 and lens cap 3 can be made from a number of materials, for example metal or plastic, and plastic is the preferred material here for several reasons. The plastic could be an extruded, molded part, for example in an inexpensive flashlight. The present description, however, relates to a heavy duty flashlight, and the plastic employed was 10,000 psi, high impact, high temperature (165.degree. F.) PVC which was machined to the appropriate size and dimensions. A particular advantage of the PVC as used here is its relative light weight and low cost compared, for example, to metal which would have the same high impact strength. The plastic too has an impact absorbing characteristic which reduces and cushions the shock to the head area of the flashlight, thus reducing the potential of damage to the bulb.

The barrel 1 serves as the conduit for the electrical current. This differs from prior flashlights in that the barrel was not in direct and continuous contact with the contact plate. Instead in the prior flashlights, the contact plate was contacted by activation of the thumb switch, which then connected to the barrel. In the prior flashlights the barrel was not in continuous contact with the contact plate 9, but was connected to the contract plate through the thumb switch. As noted above, the thumb switch of the prior art was frequently the weakest link in the dependability and functioning of the light.

The barrel 1 of the present invention can be a conductive metal, and in this instance 1/8 inch aluminum tubing was employed. This provides light weight, strength and current carrying capacity. Other metals could just as easily have been employed. Similarly, the barrel could be anodized so long as each end was left unanodized for the purpose of making a contact. The barrel 1 could for the reasons given above be made of plastic with a conductive contact strip or coating on the inner surface running the length of the barrel. The batteries 29 are arranged in the barrel in a conventional manner and are in electrical contact with contact 14.

In order to provide a firm grip, a diamond knurl 6 has been placed along a portion of barrel 1 and on lens cap 3 for removal of the cap.

At the lower end of the flashlight, seated in cap 17 is a coil spring providing bias against the batteries 29, thus maintaining sufficiently close contact that an electrical current can flow. As noted above, there are a number of conventional elements performing unconventional functions herein. The spring 15 seated in cap 17 is such an element. These two elements, i.e., the coil spring 15, biasing means, and the cap 17, form the switch of the present invention.

Referring to FIG. 2, it can be seen that spring 15 is seated in cap 17 by means of a base 27 which is adapted to snap into annular groove 30 located in the cap immediately below the threads 31. In addition, the base 27 is anchored by a flange (not shown) engaged in hole 28 in the cap 17.

Referring again to FIG. 1, the cap 17 is shown mounted by means of threads 31 on threads 16 on the lower end of barrel 1. The threads are right threads (left-hand threads could also be used) such that lower edge 26 of barrel 1 is drawn into cap 17 as the cap is rotated in a clockwise direction. The switch is closed by rotating the cap 17 in a clockwise direction until the lower edge 26 contacts base 27 of the spring 15. When this contact occurs the circuit is closed and the current will flow, and in this case the flashlight will light.

In FIG. 1 the switch is shown in the off position, and a small gap 25 is present between the lower edge 26 of barrel 1 and the base 27 of spring 15. In the configuration shown in FIG. 1, the switch is off.

The figures also represent a further refinement of the present invention which is the latch 22 and notch indicators 18 and 19. Referring now to FIG. 3, the notches which are in the lower edge 26 of barrel 1 can be clearly seen. Notch 18 is characterized as the off notch, and notch 19 is characterized as the on notch. The position of the on notch 19 is important since it must be such that lower edge 26 is in electrical contact with the base 27 of spring 15. The location of off notch 18 is not important, other than it be spaced at a sufficient space from notch 19 that a gap is created in order to break the circuit.

Referring back to FIG. 1, latch 22 is engaged in off notch 18. Latch 22 is seated in housing 20 and is biased against the lower edge 26 of barrel 1 by spring 21. Annular shoulder 24 on latch 22 cooperates with annular lip 23 to prevent latch 22 from leaving the housing when the cap is entirely removed from the barrel 1.

It is readily apparent that the cap 17 must either be made from a non-conductor or that the spring 15, as seated therein, must be insulated since the cap 17 is in contact with the barrel 1. In the present embodiment the cap is machined from PVC, as described above. It can be seen that use of a non-conducting tube with internal contact stripes as described above would also be a manner of handling that factor.

The flashlight depicted in FIG. 1 shows three batteries; however, any number of batteries, e.g., 1 to 7, may conveniently be employed.

For the configuration depicted in the figures, the spring is wound in a counterclockwise direction in order to reduce and counterbalance the effect of the torque as the cap is rotated into the on position. Similarly, the spring 15 is anchored to prevent it from moving and possibly contacting latch 22 which is always in contact with the barrel 1 when assembled in a ready-to-use configuration. Another refinement is the slight taper given to cap 17 to lessen the probability of the flashlight slipping out of the hand.

In the present configuration, an American standard thread, i.e., 12 thread, was employed. It has been found that thread cuts of less than 12 (12 threads per inch) are too deep and would weaken the 1/8 inch tubing. Possibly up to an 18 thread could be employed and preferably no more than 14 thread since these threads are too fine for this type of application and can result in cross-threading or jamming.

It should be noted that there is a greater thread length on the barrel 1, i.e., threads 16, than provided in cap 17 so that the lower edge of barrel 1 can be brought against the base 27 of spring 15. A sufficient minimum difference is about 1/16 inch.

It is readily apparent that the present switch can be employed with other devices than a flashlight and can be used with alternating current as well as direct current. The present switch can be employed alone or in conjunction with other types of switch and can be used to replace virtually every type of switch now in use. For example, the threads need only be sufficient to rotate the cap from an on to an off position with a check or stop to prevent removal of the cap from the tube member of the switch. The tube member itself need only be sufficient to mount the cap thereon. The switch contacts would be as present here, i.e., through the tube member and through a base member position on the axis of the tube member in electrically contacting alignment with the tube member. A spring 15, for example, would not be necessary in a wall switch employing the present switch and would be replaced with a prong or other means to contact the electrical circuit.

Claims

The invention claimed is:

1. An electrical switch comprising: a tube member having threads toward one end thereof, a non-conducting cap member having threads therein and engaged with said threads on said tube member and rotatable thereon, a first electrical contact mounted in the top of said cap member and aligned with the end of said tube member removably engaging said end and forming an electrical contact therewith, such engagement being subject to the relative rotation of the cap and tube members to draw the cap member onto said tube member, said tube member being a second electrical contact and a depressable latch in said cap member in depressed contact with the end of said tube member and a notch in the end of said tube member removably engaging said latch.

2. The electrical switch according to claim 1 wherein said notch is positioned for engaging said latch therein and bringing said first and second electrical contacts into electrical engagement.

3. The electrical switch according to claim 1 comprising a first notch positioned for engaging said latch therein and holding said first and second electrical contacts out of electrical engagement.

4. The electrical switch according to claim 3 wherein said first electrical contact comprises a biasing means.

5. The electrical switch according to claim 4 wherein said threads on said tube member are longer than said threads in said cap member.

6. The electrical switch according to claim 1 comprising an elongated tube member adapted to hold batteries, an illuminating means mounted on one end of said tube member opposite said cap member and electrically contacting said tube member.