Abstract:
A pocket sized telescopic level apparatus includes a plurality of at least three telescoping tubular sections including a largest section and sequentially smaller sections, each section having an exterior diameter and a longitudinal bore with an interior diameter, and wherein the sections are of sequentially larger external diameter so that one section fits into an adjacent section and all sections are contained upon the largest section in a collapsed position. A level bubble member is disposed at an end portion of the largest section and a plurality of shims form interfaces between the end portions of adjacent sections upon extension of the apparatus. The shims are tubularly shaped and positioned between the outer wall of an end portion of one section and the inner wall of an adjacent section.

Description:
FIELD OF THE INVENTION 
     1. Field Of The Invention 
     The present invention relates to extendable levels and more particularly relates to a pocket sized extendable level that includes multiple telescoping sections that are extendable and wherein the entire level apparatus can fit within the pocket of a user, being on the order of six to eight (6-8) inches in length. 
     2. General Background 
     A number of level constructions have been patented which relate to extensions of levels. As seen in levels referenced by the below discussed U.S. Pat. Nos. 4,862,595; 4,607,437; 4,130,943; 3,648,378; 3,104,477; 2,879,606 and 3,161,964, these levels usually involve the use of two sleeve like extensions Which collapse over a center or core unit and are designed to varying length, typically being heavy duty levels used in construction trades. 
     The amount of extension afforded these heavy levels ranges anywhere from two to eight (2-8) feet for example. The various extension lengths are either predetermined and to fixed positions increments or involve some type of locking mechanism to hold the extension pieces in place. 
     Levels generally provide for an extension capacity which is limited to about double the length of the level when it is collapsed. These above mentioned levels are typically designed to be employed as surface truing tools in such applications as door hanging, door frame alignment, elevator rail bracket positioning and the like. 
     U.S. Pat. No. 2,551,524 employs only one extension sleeve but it is otherwise similar to the above discussed patents. Another level is shown in U.S. Pat. No. 3,277,579 which is actually telescopic in design and capable of aligning points in space (as opposed to leveling of surfaces), but it too is designed to be large and heavy for use in the construction trades, intended to extend about six to eight (6-8) feet between ceilings and floors. This apparatus is quite large even when completely collapsed, and specifically involves the use of positioning bolts. Its spring mechanism requires the application of pressure at both ends. 
     A carpenter&#39;s level is shown in U.S. Pat. No. 2,879,606 issued to J. J. Olivere. The device employs level bubbles and has a pair of elongated tubular sleeve elements telescopically mounted over opposite ends of a central member, the ends meet each other approximately at the center of the central member. 
     In U.S. Pat. No. 3,104,477 entitled &#34;Level&#34; issued to B. J. Edwill provides a pair of level members that extend with respect to each other upon two cylindrical rails. In one embodiment, the extendable members move away from a central level portion. 
     In the Miles U.S. Pat. No. 3,161,964 entitled &#34;Elevator Rail Bracket Positioning Device&#34;, three sections of a telescoping level are shown including a smaller central section and a pair of larger side sections. 
     In the Thingstad U.S. Pat. No. 3,648,378 entitled &#34;Arrangements in an Extensible Air Bubble Type Level&#34;, there is provided a pair of side mounted extensible parts which move away from a center level. 
     In the Moore U.S. Pat. No. 3,811,197, a center smaller level portion is provided with a pair of larger extensible sleeves that mount thereon in telescoping fashion and extend so as to expand the overall length of the level. 
     A vertical telescoping level is the subject of the Murphy U.S. Pat. No. 3,277,579. The apparatus includes an inner tube and an outer tube with a leveling assembly carried by the larger tube. 
     The Talbot U.S. Pat. No. 4,103,943 entitled &#34;Extension Level&#34; provides a carpenter&#39;s level extendable preferably from the length of 24 to the length of 48 inches in six inch increments. The level includes an I-Beam shaped bay section with right and left extension members slidably mounted thereon. The extension members engage either side of the base at tracks formed by the side extensions of the eye. 
     Another patent that relates to a center level member with extensible side members is the McSorley U.S. Pat. No. 4,607,437. 
     A small level that can be carried in the pocket of the user is seen in the Rohlinger patent entitled &#34;Level and Collapsible Ruler&#34;. The &#39;764 patent provides a combination collapsible ruler and level, and includes a prestress coilable and uncoilable spring strip ruler with a level tube mounting block mounted intermediate the strip ends. The mounting block has a foot portion which engages the supporting surface to make the spring strip self-supporting on a surface with the level tube in the proper plane. When collapsed, the spring strip forms two coils which abut adjacent the level mounting block to provide for convenient handling. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a pocket level that is designed to assist in the true alignment of points in space. It is intended for instance to be used in nursing so as to correctly align the phlebostatic axis of a patient (located at the fourth ICS at the mid-axillary line), otherwise known as the level of the mitral valve, with the zero reference point or stop cock of a strain gauge transducer that is connected to an invasive hemodynamic monitoring line. 
     With this alignment, hydrostatic effects of position change and head rest position elevation are eliminated and pressures recorded are considered true intravascular readings. Pressure lines requiring this technique as the standard of measurement are: left atrial, left ventricular, pulmonary artery, right atrial, central venous, pulmonary artery occlusive pressures, right ventricular pressures and systemic arterial pressures. 
     The apparatus of the present invention may be used to align the ventricle of the brain with a strain gauge transducer for the purpose of intracranial pressure monitoring and for intraventricular drains where CSF is drained into a closed bag. The level of this bag in relationship to the patient&#39;s ventricle dictates the amount of fluid removed per physician&#39;s order. 
     It is an object of the present invention to provide a small and lightweight level so as to be pocket size and easily portable, preferably being capable of clipping or attaching to a shirt pocket or jacket pocket. It is an object of the present invention to provide a level that can be easily calibrated. 
     It is another object of the present invention to provide infinite adjustability throughout its extension range and without complex lock-down mechanisms. 
     It is an object of the present invention to provide a pocket size level that preferably has a minimum of four hundred percent (400%) increase in its fully extended position over its collapsed configuration and with a maximum length of for example thirty-four (34) inches and with a minimum length of about 8 inches. These lengths are compatible with pocket size requirements and the nursing applications described above. 
     It is an object of the present invention to provide an improved pocket level construction that is capable of being extended and retracted between or through openings in object existing between two points requiring alignment such as for example bed rails in the nursing application described above. 
     It is an object of the present invention to provide a pocket level apparatus of improved construction that provides tight tolerances so as to insure accurate readings over extended periods of use. 
     The preferred construction of the present invention is to provide a pocket level having circular or square sections wherein the sections overlap approximately one and one half to two (11/2-2) inches and wherein curved shims are used to eliminate play between adjacent sections. 
     The present invention thus provides a pocket size telescoping level apparatus that includes a plurality of at least three telescoping tubular sections including a largest section and sequentially smaller sections, each section having an exterior diameter and a longitudinal bore with an interior diameter and wherein the sections are sequentially larger external diameters so that one section fits into an adjacent section and all of the sections are contained within the largest section when the level is folded into a fully collapsed position. A level bubble member is disposed at one end portion of the largest section and a plurality of tubular shims form an interface between the end portions of adjacent sections, the shims being positioned between the outer wall of an end of one section and the inner wall of the adjacent section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understandinq of the nature and objects of the present invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings, in which like parts are given like reference numerals, and wherein: 
     FIG. 1 is a side view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 2 is a front view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 3 is a schematic view illustrating the storage of the apparatus of the present invention in the pocket of a user; 
     FIG. 4 is a schematic view of the preferred embodiment of the apparatus of the present invention illustrating its use with a patient; 
     FIG. 5 is a side fragmentary view of the preferred embodiment of the apparatus of the present invention; 
     FIG. 6 is a side sectional view of the preferred embodiment of the apparatus of the present invention; and 
     FIG. 7 is a fragmentary sectional view illustrating deflection between adjacent tubular sections. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1, 2 and 5-6 illustrate the preferred embodiment of the apparatus of the present invention designated generally by the numeral 10. Pocket level 10 includes a pocket sized tubular structure that includes an upper end portion 11 and a lower end portion 12. The end portion 12 can be in the form of a sphere having an outer diameter substantially equal to the outer diameter of upper end portion 11. 
     The largest tubular section 13 provides an open end portion 14 and a closed end portion 15. Level bubble assembly 16 is carried at end portion 15 of large section 13 as shown in FIGS. 1 and 2. A ring 17 attaches to end portion 18 of level bubble 16 at opening 19. Clip 20 can be used for affixing level apparatus 10 to the pocket of a user as shown in FIG. 3, the user being designated as 21 in phantom lines and the pocket of the user in phantom lines by the numeral 22. In FIG. 4, use of level 10 with a patient 23 is shown with the level 10 being used to level the stopcock 25a on transducer 25 to the phlebostatic axis 24 on a patient 23. 
     A plurality of tubular sections 30-34 are contained within larger tubular section 13 as shown in FIGS. 1-2 and 5-6. The smallest tubular section 34 is attached to sphere 12. During extension, each section 30-34 moves in a direction as shown by the arrows 35 when extending level 10. If FIG. 6, a partial sectional side view is shown illustrating the largest section 13, the next smallest section 30 and the next sequentially smaller section 31. It should be understood, however that the joint shown in FIG. 6 between tubular sections 13 and 30 and the joint between sections 30 and 31 is a joint construction that is repeated at the interface between sections 31-32; 32-33; and 33-34. In FIG. 6, only two joints (between sections 13-30 and 30-31) are shown for purposes of illustration. 
     The tubular sections 13 and 30-35 are hollow, each providing a bore which is hollow and cylindrical as shown in FIG. 6. Bore 36 defines the hollow interior of largest cylindrical section 13 and bore 37 defines the cylindrical hollow interior of section 30 while bore 38 defines the hollow cylindrical section of the section 31. 
     In FIG. 6 and 7, an enlarged sectional view is shown of the apparatus 10 in a straight, elongated position. In FIG. 7, an exaggerated scale view is illustrated to show the deflection that occurs if the apparatus is subjected to the stress of its own weight such as when supported at its end portion 15 and in a fully extended position. It should be understood however that the scale of FIG. 7 is greatly exaggerated for purposes of illustration. FIG. 7 is used to illustrate that the shims 27, 28 lessen the deflection when the apparatus 10 is fully extended than would otherwise occur without the presence of the shims 27, 28. 
     In FIG. 6, a pair of joints, 21, 22 are shown, the joint 21 defining an interface between the enlarged section 13 and the tubular section 30. The joint 22 illustrates the interface between the joint 30 and the joint 31. Cylindrical shims 26, 27 are shown as interfacing between the tubular sections 13-30 and 30-31 respectively. The use of the curved shims 26, 27 defines an interface that is formed between the outer surface 28 of shim 26 and the inner surface 29 of shim 27 with outer surface 42 of tubular section 30. 
     The joint 22 shows an interface defined by the shim 28 and more particularly the outer surface 38 of shim 27 and the inner surface 39 which abuts the outer surface 44 of tubular section 31, the inner surface 45 being also illustrated. That surface 45 would form a connection with the next shim (not shown). The largest section 13 provides an outer surface 40 which is the external surface of the apparatus upon collapse as shown in FIGS. 1 and 2. The inner surface 41 of tubular section 13 registers with the outer surface 28 of shim 27 as shown in FIG. 6. Each section 13 and 30-33 provides annular crimped end portions in the form of annular shoulders 46-49 (FIGS. 6 and 7). 
     Upon extension of the apparatus 10, each of the annular shoulders 46-49 functions as a stop against a shim as seen in FIGS. 6 and 7. For example, extension movement of the section 30 is stopped with respect to sections 13 and 31 because shoulders 46 and 48 abut shim 27 and shoulders 47-49 abut shim 28. Each section 32, 33, has a joint 21, 22 such as is shown in FIG. 6 using such shims and annular shoulders. 
     For purposes of illustration, FIG. 7 shows that the shims 27 and 28 provide a diameter that extends preferably one to one and one half (1-11/2) inches in length to minimize deflection. In FIG. 7, an over-exaggerated scale is provided to show that some deflection might occur, but the shims minimize the deflection thus providing accuracy even when the apparatus is fully extended such as for example thirty-eight to forty (38--40) inches which can be four times the collapsed length of the apparatus 10 of for example six to eight (6-8) inches. The use of the shims 27-28 as shown in FIGS. 6 and 7 helps minimize deflection between the end portions 15-12 of the apparatus 10 even when fully or partially extended, the position shown in FIG. 4. The shims 27, 28 could be in two parts, 27a-27b and 28a-28b. The part 27a would be attached to and travel with the end of section 30 on the outer surface thereof. The shim part 27b would be attached to and travel with the end of section 13, attached to the inside surface 41 thereof. This use of split shims 27a-27b (and similarly 28a-28b) affords better support at intermediate extension positions, such as half extended. 
     An exemplary embodiment provides an extendable pocket size level that extends to about thirty four inches (34&#34;) and collapses to about seven to eight inches (7-8&#34;). The sections 30-34 are each about six inches (6&#34;) in length. The largest section 13 which includes level bubble assembly 16 is about eight inches (8&#34;) in length. Total diametrical clearance (i.e., the clearance between the outer diameter of a curved shim 26, 27 and the inner diameter of a section bore 36, 37) is about 0.25 mm or less, giving very small overall deflection during use and when fully extended, and less than one quarter inch (1/4&#34;) deflection for thirty four inches (34&#34;) of length. This provides a preferred ratio between section length (of about six inches (6&#34;) or one hundred fifty to one hundred sixty millimeters (150-160 mm) and overall diametrical clearance of greater than five hundred or about six hundred fifty to one (650:1) in the above example. Each shim 26, 27 is about one fifth to one quarter of the adjacent section 13, 30-34 length. 
     The following table 1 shows the parts including number and description as used herein and in the accompanying drawings: 
     
                       TABLE 1______________________________________PART NO.       DESCRIPTION______________________________________10             level apparatus11             upper end12             lower end13             largest tubular section14             open end portion15             closed end portion16             level bubble assembly17             ring18             end portion of level bubble19             opening20             clip21             joint22             joint23             patient24             phlebostatic axis25             transducer25a            stopcock26             curved shim27             curved shim27a            shim28             outer surface29             inner surface30             tubular section31             tubular section32             tubular section33             tubular section34             smallest tubular section35             arrows36             bore37             bore38             outer surface39             inner surface40             outside surface41             bore inner wall42             outer surface43             inner surface44             outer surface45             inner surface46             annular shoulder47             annular shoulder48             annular shoulder49             annular shoulder______________________________________ 
    
     Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.