Abstract:
A fluid-actuated level device for use, for instance, in the building trades, discovers points lying on a horizontal plane with a reference point. The level device has a tube with a referenceend and a working-end, and a housing unit attached to the reference-end. Electrodes in the housing unit measure fluid-levels in the reference-end. When the fluid-level in the working-end is positioned in the horizontal plane containing the reference point, then the level device emits a signal; in one embodiment, this signal is a single continuous sound. When the working-end is positioned slightly higher than the reference point, a second signal is emitted; in one embodiment, this signal is an intermittent sound. The second intermittent sound notifies the worker that the fluid-level in the working-end is too high relative to the reference plane, i.e., the worker has “overshot” the reference plane. Also provided are embodiments having a tube window, an alignment window, and a slidable backing assembly. The tube window provides visual access to the electrodes in the tube. The alignment window enables the reference markers to be in close proximity on adjacent sides of the tube at the reference-end. A slidable backing assembly enables the housing unit to be slidably adjusted along a continuous vertical line after it is affixed to a reference point. Lastly, a method for using a non-transparent tube is provided.

Description:
FIELD OF THE INVENTION 
     The present disclosure relates generally to devices used in identifying two or more points on a horizontal plane, specifically, a fluid-actuated level device for locating points on a level plane. 
     BACKGROUND 
     Numerous level devices have been used to identify points on a horizontal plane. Level devices are particularly useful in the building industries where positioning a structure on a level plane is critical to the design and implementation of the structure. Such structures include, for example, foundations, decks, counter-tops, suspended ceilings, suspended sprinkler systems, pools, fences, and sewer lines. Two level devices are commonly used in the building industries: bubble levels and fluid-actuated levels. Bubble levels are well-known in the prior art. Two types of fluid-actuated levels are generally known in the prior art. Both types operate according to the same general principle: if fluid is allowed to flow through a tube and the end of the tube are raised above the body of the tube, then gravity pulls the fluid such that the fluid-levels at the tube ends settle on the same horizontal plane. The first type of fluid-actuated level generally consists of a sealed tube with a pressure-sensing device connected to a tube end for measuring air pressure in an air cavity at the tube end. The pressure varies with the displacement in air volume at the tube ends caused by the gravitational pull on the fluid; the sensing device may thus be calibrated to a particular air pressure, typically a pressure corresponding to when the fluid-levels in the two ends lie on a horizontal plane. One drawback of the pressure-sensitive fluid-actuated level is its cost, which is often prohibitive for commonplace construction applications. 
     The second type of fluid-actuated level (generally less costly than the first type) typically uses a fluid-level sensing device connected to an end of an unsealed tube. A fluid-actuated level of this type is disclosed in U.S. Pat. No. 4,434,561 and shown in FIGS. 1-2. In FIG. 1, fluid-actuated level device  10  has a housing unit  17  and a tube  11  for holding an electrically conducting fluid  18 , typically tap water. Tube  11  has a reference-end  21 , connected to the housing unit  17 , and a working-end  20 . Working-end  20  is used by a worker for locating level points in a proposed horizontal plane, or reference plane. Housing unit  17  has a base electrode  15  and a reference electrode  14  inserted through the walls of the reference-end  21  for detecting the fluid-level in the tube  11 . Electrodes  14 ,  15  are connected to a power source  12  and a signal generator  13 , such as a sound or light generator, and form a circuit when connected. In operation, conducting fluid  18  in reference-end  21  submerges base electrode  15 . When a worker lifts the fluid-level in working-end  20  higher, the fluid level in reference-end  21  rises to make contact with reference electrode  14 . When conductive fluid  18  contacts reference electrode  14 , an electrical circuit is formed which enables current from electrical source  12  to actuate signal generator  13 . Signal generator  13  then emits a sound, light or other signal to indicate that the fluid-level in the working-end  20  has contacted the reference plane as defined by the reference electrode  14 ; this signal will be called the reference signal. In the prior art, housing unit  17  conceals electrodes  14 ,  15  and reference-end  21 ; external reference marking  16 , which is aligned with the reference electrode  14 , is therefore placed on the outside of housing unit  17  to indicate the reference plane to the worker. 
     FIG. 2 illustrates the general operation of fluid-actuated level device  10 . A worker fills tube  11  of fluid-actuated level  10  with fluid and affixes housing unit  17  to, for example, a wall  19 . Housing unit  17  is affixed such that external reference marking  16  is aligned with the proposed reference plane  18  (shown as a dotted-line). Working-end  20  (opposite housing unit  17 ) is shown extended across the wall  19 ; the water-level in working-end  20  is aligned with reference plane  18 . To discover the reference plane, the worker moves working-end  20  upward until the fluid-level in the working-end  20  reaches the same height as the external reference marking  16  on housing unit  17 . Due to the action of gravity on the fluid in tube  11  (the body of the tube  11  must be positioned below the tube ends), the fluid within housing unit  17  at this point has submerged base electrode  15  and reference electrode  14 ; this completes a circuit that activates signal generator  13 . The worker hears a reference signal which indicates the level point. In this manner, the working-end  20  may be used to locate a multitude of level points lying on a reference plane roughly defined by a circle centered on housing unit  17  with a radius equal to the tube length. Level points approximately 100 feet from housing unit  17  may be accurately discovered in this manner. The fluid-actuated device of FIGS. 1-2 is especially useful when level points are sought by a worker working alone in rough and un-even terrain, or, for example, where level points need to be discovered around a corner structure. In this case, the worker takes working-end  20  around the corner structure and moves working-end  20  in a vertical manner until a reference signal is heard from housing unit  17 . 
     The fluid-actuated level device of FIGS. 1-2 has a number of limitations. First, the level device  10  does not communicate to the worker whether the fluid-level in the working-end  20  is positioned too high; on the contrary, a single reference signal is given so long as the fluid-level in the working end is either in the reference plane or at any point above the reference plane. This introduces imprecision when a worker, due to, e.g., fatigue or rough terrain, accidentally adjusts the working-end too high after hearing the signal emitted from the device. Second, normal usage of the level device  10  results in dirt and fluid residue accumulation around the electrodes  14 ,  15  in the tube; this may result in a “wicking” effect. Wicking is caused when fluid clings to the dirt and fluid residue around the electrodes to form a conductive bridge between the probes that persists beyond the point at which the fluid-level, under normal conditions, would disconnect the electrodes  14 ,  15 . In the prior art, a worker is unable to efficiently detect a possible wicking condition because visual access to the tube  11  and the electrodes  14   15  is not provided. Third, a worker typically affixes the housing unit  17  to a reference plane by aligning a single external reference marking  16  on the outer edge of housing unit  17  to the reference point. Housing unit, however, has a greater width than the tube  11 , and therefore any skew or tilt introduced to the housing unit  17  when affixing it (or using it) results in a degree of imprecision equal to the distance between the horizontal planes defined by the reference plane and the external reference marking  16  (the greater the distance, the greater the degree of potential imprecision). 
     Fourth, housing unit  17  is typically affixed by driving nails or screws for attaching the housing unit  17  into a structure. This often results in imprecision because the nail or screw is driven at an awkward angle due to a lack of care by the worker or by irregularities in the structural medium (e.g., a knot in wood). Because readjustment is typically burdensome (requiring removal and replacement of the nail or screw), such imprecision is typically tolerated. Lastly, the tube ends should generally consist of transparent or otherwise translucent material to enable the worker to view the fluid-levels; as a result, the entire tube is typically constructed of a single molded piece of transparent plastic. Because the tube may be in excess of one-hundred feet long, the cost of transparent tubing may be significant. 
     SUMMARY 
     A fluid-actuated level device (hereafter, “level device”) for use, for instance, in the building trades, is disclosed. The level device enables a worker to discover points lying on a horizontal plane defined by a reference point. The level device has a tube with a reference-end and a working-end, and a housing unit attached to the reference-end. Electrodes in the housing unit measure fluid-levels in the reference-end. When the fluid-level in the working-end is positioned in the horizontal plane containing the reference point, then the level device emits a signal; in one embodiment, this signal is a single continuous sound. When the working-end is positioned slightly higher than the reference point, a second signal is emitted; in one embodiment, this signal is an intermittent sound. The second intermittent sound notifies the worker that the fluid-level in the working-end is too high relative to the reference plane, i.e., the worker has “overshot” the reference plane. Also provided are embodiments having a tube window, an alignment window, and a slidable backing assembly. The tube window provides visual access to the electrodes in the tube. The alignment window enables the reference markers to be in close proximity on adjacent sides of the tube at the reference-end. A slidable backing assembly enables the housing unit to be slidably adjusted along a continuous vertical line after it is affixed to a reference point. Lastly, a method for using a non-transparent tube is provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a prior art fluid-actuated level device. 
     FIG. 2 illustrates the general operation of a prior art fluid-actuated level device. 
     FIG. 3 illustrates a fluid-actuated level device according to one embodiment. 
     FIG. 4 illustrates a fluid-actuated level device according to one embodiment with the molded front cover removed. 
     FIG. 5 illustrates a tube window according. to one embodiment. 
     FIG. 6 is a schematic diagram illustrating an apparatus for emitting signals upon detection of fluid-levels according to one embodiment. 
     FIG. 7 is a circuit diagram of an apparatus for emitting signals upon detection of fluid-levels according to one embodiment. 
     FIG. 8 is a parts list for the circuit shown in FIG.  7 . 
     FIG. 9 is a perspective view of a slidable backing assembly according to one embodiment. 
     FIG. 10 is another perspective view of a slidable backing assembly according the one embodiment. 
     FIG. 11 illustrates a housing unit connected to a slidable backing assembly according the one embodiment. 
     FIG. 12 illustrates the apparatus implementing a non-transparent tube section according to one embodiment. 
     FIG. 13 illustrates a water-filler according to one embodiment. 
    
    
     DETAILED DESCRIPTION 
     FIG. 3 illustrates a fluid-actuated level device  51  according to one embodiment. Housing unit  54  comprises a molded plastic exterior consisting of a molded cover component  57  connected by four screws  55  to a molded backing component  58 . Housing unit  54  has an alignment window  59  located roughly in the center of molded cover and backing components  57 ,  58 . Tube channel structure  66  comprises the right longitudinal section of housing unit  54  adjacent to the right edge of alignment window  59 ; a cylindrical tube channel runs inside tube channel structure  66  from bottom tube opening  89  to top tube opening  91 . Tube channel structure  66  is adapted for holding a tube  85  by means of a clamping effect caused by joining the molded cover and backing components  57 ,  58 . A left external reference marking  61  is located on the tube channel structure  66  in alignment window  59 , and a right external reference marking  62  is located on the edge of tube channel structure  66  opposite the left external reference marking  61 . The external markings  61 ,  62  are aligned with a reference electrode (not shown). In this embodiment, alignment window  59  enables placement of external reference markings  61 ,  62  on edges of tube channel structure  66  adjacent reference electrode (not shown), in contrast to edges of housing unit  54  as in the prior art; the increased proximity between external reference markings  61 ,  62  minimizes loss of precision caused by rotational mis-adjustments (skewed placement) when affixing housing unit  54  to a reference structure  71 . In addition, increased proximity enhances level device accuracy by permitting greater ease in using both external marks for alignment purposes; in prior art devices, the greater distance separating the external reference marks  61 ,  62  often renders impossible or impractical the use of both external reference markings for alignment purposes, and typically alignment to only one (external reference marking) is performed. 
     Referring back to FIG. 3, the molded cover component  57  has on-off switch  77  positioned left of alignment window  59 , and speaker holes  75  positioned below on-off switch to allow emission of audible signals. At the top and bottom center of housing unit are means for affixing level device to a reference structure to prevent accidental rotation or skewing of the level device during use. In this embodiment, the top center affixing means consists of a center hole  68  with a notch located at the top center of the hole; the bottom center affixing means consists of indented groove  69  adapted for receiving a nail, screw or other elongated hardware. The molded cover and backing components  57 ,  58  each have upper tube clamp  79  and lower tube clamp  73  for holding working-end  81  of tube  85  for convenient storage purposes. Molded plastic clamps  83  are used to clamp the hose ends to prevent fluid leakage when the level device  51  is not in use. 
     FIG. 4 illustrates a level device with the molded cover component removed according to one embodiment. An energy source  101 , in one embodiment a conventional nine volt battery, is positioned above alignment window  59  and connected to on-off switch  77  on circuit board  103 . Also connected to circuit board  103  are signal generator  105 , amplifier means  107 , and electrodes  93 ,  97 ,  99 . FIG. 5 illustrates a tube window  65  according to one embodiment. Tube window  65  comprises a rectangular cut-out portion in the tube channel structure  66  (FIG. 3) positioned between external reference markings  61 ,  63  (FIGS.  3 ). Tube window  65  permits viewing of the tube  85  and the electrodes  93 ,  97 ,  99  penetrating the tube  85 . Electrodes  93 ,  97 ,  99  are aligned as shown in FIG.  5 . Base electrode  99  is located below reference electrode  97  in tube  85 , and reference electrode  97  is located below and to the left of overshoot electrode  93 . As shown in FIG. 5, the length L 1  between base electrode  99  and reference electrode  97  is approximately one-third inch, and the length L 2  between reference electrode  97  and overshoot electrode  93  approximately one-sixteenth inch. Other embodiments may position the electrodes at a variety of lengths and orientations from one another, and may employ a variety of energy sources, and a variety of tube window shapes. 
     In operation, base electrode  99  and reference electrode  97  operate as a first switch, and base electrode  99  and overshoot electrode  93  operate as a second switch, for permitting energy from energy source  101  (FIG. 4) to drive signal generator  105  (FIG.  4 ). In this embodiment, a continuous sound is generated by signal generator  105  in response to current from the first switch (reference signal); the same continuous sound is then rendered intermittent in response to current from the second switch (hereafter, overshoot signal). Thus, when fluid-level is raised in reference-end  82  (FIG. 3) in response to vertical movement of the working-end  81  (FIG.  3 ), fluid submerges first the base electrode  99  and then the reference electrode  97 . When contact is made with the reference electrode  97 , the level device emits a reference signal. If the worker continues to raise the fluid-level in the working-end, the conductive fluid eventually rises to make contact with the overshoot electrode  93 , resulting in emission of the overshoot signal. The change from the continuous steady sound of the reference signal to the intermittent sound of the overshoot signal thus notifies the worker that the working-end is positioned too high, and must be lowered to ensure measuring precision. The overshoot electrode  93  thus enables greater measuring precision to be achieved in situations where a worker, due to, e.g., carelessness, fatigue or uneven terrain, moves the working-end too high after hearing the reference signal. In addition, when the level device is used over long distances—and especially with tubing of narrow diameter—a delay occurs before the fluid in the reference-end settles to accurately reflect the fluid-level in the working-end  81 ; this delay results in a delayed reference signal that leads a worker to a measuring point that has overshot the reference plane. The overshoot electrode solves this problem by quickly alerting the worker by the overshoot signal  93  that his measuring point is too high relative to the reference plane, and that he must lower the working-end  81  until the overshoot signal converts back to the reference signal. Other embodiments may employ different sounds and signaling means, for example, light emissions. Other embodiments may also form a second switch between the reference and overshoot electrodes  97 ,  93 . 
     As shown in FIG. 5, use of tube window  65  enables a worker to rapidly learn how to operate the level device. In particular, a worker may inspect through tube window  65  how the reference signal and overshoot signal correlate to fluid-levels in relation to the reference electrode  97  and the overshoot electrode  99  (as well as the external reference markings  61 ,  63  (FIG.  3 )). In addition, tube window  65  has the further advantage of enabling a worker to visually identify when level device functioning degrades due to the wicking effect caused by fluid deposit accumulation around the electrodes. Lastly, tube window  65  enables a worker to clean the reference-end and electrodes without removing the tube from the housing unit and without damaging the electrodes. 
     FIG. 6 is a schematic diagram illustrating an apparatus for emitting signals upon detection of fluid-levels according to one embodiment. When conductive fluid  100  submerges the base electrode  99  and the reference electrode  97 , a current is passed between the base and reference electrodes  99 ,  97  which is detected by amplifier  131 A. After amplifier  131 A detects a current from the reference electrode  97 , current is passed from energy source  101  through output terminals  135  to signal generator  104 . Signal generator  104  then emits a reference signal consisting of a steady, uniform audible sound. When conductive fluid  100  submerges the base electrode  99  and the overshoot electrode  93 , a current is passed between the base and overshoot electrodes  99 ,  93  which is detected by amplifier  131 B. When amplifier  131 B detects a current from the overshoot electrode  93 , current is passed from energy source  101  through output terminals  135  to signal generator  104 . Signal generator  104  then emits an overshoot signal consisting of the sound of the reference signal rendered intermittently. Energy source  101  is connected to the power supply terminals  137  and ground terminals  139  of amplifiers  131 A,  131 B. 
     FIG. 7 provides a circuit diagram of an apparatus for emitting signals upon detection of fluid-levels according to one embodiment. The circuitry may be implemented by using, for example, a CD40106 Hex Schmitt Trigger manufactured by National Semiconductor of Arlington, Tex. Base electrode  99  is connected to ground, reference electrode  97  is connected to amplifier  131 A, and overshoot electrode is connected to amplifier  131 B. Amplifiers  131 A and  131 B use identical circuitry. Amplifier  131 A comprises a Schmitt Trigger U 1 -C with inputs from resistor R 7 , connected to a  9  volt power source, and from reference electrode  97 . Amplifier  131 B comprises a Schmitt Trigger U 1 -A with inputs from resistor R 8 , connected to a nine volt power source, and from overshoot electrode  93 . Signal generator  104  takes inputs from amplifiers  131 A,  131 B. Signal generator  104  uses three Schmitt Triggers U 1 -D, U 1 -E, U 1 -F, four resistors R 2 , R 3 , R 5 , R 6 , three capacitors C 2 , C 3 , C 4 , four diodes DI, D 2 , D 3 , D 5  and a buzzer B 1  connected as shown in FIG.  7 . FIG. 8 is a parts list describing the quantity, value, reference number, and description of the parts in the circuit shown in FIG.  7 . Numerous embodiments for implementing amplifiers  131 A,  131 B and signal generator  104  are known in the art, and the present disclosure is not limited to the one described herein. 
     As shown in FIG. 3, housing unit may be attached to a slidable backing assembly  67  having a plurality of attachment holes  91  for conveniently affixing level device  51  to a structure. FIG. 9 illustrates a perspective view of a slidable backing assembly  67  according to one embodiment. In this embodiment, the slidable backing assembly  67  consists of a backing plate  149  with an upper stem canal  151 , a lower stem canal  153 , and a backing channel  159  running vertically through the center of backing plate  149 . An upper threaded stem  155  projects through upper stem canal  151 , and a lower threaded stem  157  projects through lower stem canal  153 . Threaded stems  155 ,  157  are used to connect housing unit  54  (FIG.  3 ). FIG. 10 illustrates another perspective view of a slidable backing assembly  67  according to one embodiment. Threaded stems  155 ,  157  are connected to rectangular stem holder  161 . Rectangular stem holder  161  is adapted to slide vertically in backing channel  159 . In this embodiment, rectangular stem holder  161  and backing plate  149  each consist of a single piece of sheet metal. 
     FIG. 11 illustrates a housing unit connected to a slidable backing assembly  67  according to one embodiment. Housing unit  54  is aligned between upper threaded stem (not visible) and lower threaded stem  157 . Lower threaded stem  157  is inserted through indented groove  69 , and upper threaded stem is inserted through center hole  68  and attached by nut  53 . In operation, nut  53  is tightened on upper threaded stem, compressing housing unit  54  to slidable backing assembly  67 . When nut  53  is loosened, housing unit  54  may be adjusted vertically to any position permitted by the stem canals (FIG. 8) in which the threaded stems slide. This permits alignment of the level device  51  to a high degree of accuracy. Referring back to FIG. 3, a worker typically applies a reference mark  63  to a structure  71 . Without a slidable backing assembly  67 , the connecting means  68 ,  69  of housing unit  54  must be carefully aligned to reference mark  63 . Even after careful alignment, however, a worker (from, e.g., carelessness or fatigue) may improperly attach screws or nails to the structure for affixing the housing unit  54 , thus causing measuring errors. Use of slidable backing assembly  67  enables a worker to quickly affix the slidable backing assembly  67  in an approximate relationship to the reference mark  63 ; housing unit  54  may then be fine-tuned to the reference mark  63  by loosening nut  53  and moving the housing unit  54  along a vertical continuum permitted by slidable backing assembly  67 . In addition, without the slidable backing assembly  67 , housing unit  54  is typically affixed to a structure using the center hole  68  and indented groove  69 , located at the top and bottom of housing unit  54 . Often, however, a proposed reference plane is located above or equal to the surface of an affixing structure; in this situation, the center hole  68  cannot be used to affix the housing unit  54 , and the housing unit  54  cannot therefore be properly attached. Use of the slidable backing assembly  67  extends the vertical reach of the housing unit  54  to remedy this situation. For example, housing unit  54  may be securely affixed to the structure by merely affixing the lower portion of the slidable backing assembly  67  to the structure. If the reach provided in this manner is still insufficient, the housing unit  54  may be adjusted in the slidable backing assembly  67  an additional amount to reach a significant range of reference points lying above a given structure. 
     FIG. 12 illustrates the apparatus implementing a non-transparent tube section according to one embodiment. In this embodiment, non-transparent hose  161  is coupled at each end to lengths of transparent tubing constituting the reference-end  82  and working-end  81 ; the resulting tube will be referred to as the tube assembly. Reference-end  82  and working-end  81  are coupled to non-transparent hose  161  using conventional hose adapters  163 . Conventional, inexpensive garden hose may be used as non-transparent tube  161  to substantially increase the distances at which level device  51  may discover level points for minimal cost. A drawback, however, to using non-transparent tubing  161  is that air-bubbles—which degrade the accuracy of the level device—are not detectable through the non-transparent walls of the tube. Thus, the use of inexpensive, non-transparent hose is typically discouraged. A method is provided for implementing a non-transparent tube section by means of water-filler  181 . 
     FIG. 13 illustrates a water-filler according to one embodiment. Water-filler  181  has an adapter  187  for attaching to a water source (typically a faucet), a nozzle  185  for insertion into transparent hose end for filling hose, and a flow control valve  183 . Referring to FIGS. 12-13, the tube assembly may be safely filled without trapping water-bubbles using the following method: first, attaching two transparent tube lengths  81 ,  82  to the ends of non-transparent tube  161  by means of conventional hose adapters  163 ; second, attaching an open end of one transparent tube length, typically the working-end  81 , to the nozzle  185  of water-filler  181 ; third, opening flow control valve  183  to permit pressurized water to flow through tube assembly; and fourth, closing flow control valve  183  after air-bubbles are no longer visible exiting the other end of the tube assembly, typically the reference-end. In this manner, air-bubbles may be flushed from the tube assembly by means of continuous water pressure applied to the tube assembly end. In general, any conventional fluid filler device adapted for insertion into a hose end is suitable; one such water-filler device is manufactured by the National Latex Products Company of Ashland, Ohio, and sold in a product called Splash Baseball™ with UPC number 7506003802.