Abstract:
For decades, a mainstay of electrical and electronic testing has been the conventional use of the multi-meter that used a pair of probes to connect the Device Under Test to the meter. This often proves inadequate for present-day testing because more than one simultaneous or alternate reading or the connection of another testing tool and the reading of its effect on the DUT is often required. The Dual-Function Switch and Lead set (DFSL) of the present invention provides a switch and lead set interfacing two multi-meters, or one multi-meter and one test device or instrument with the DUT, while using the traditional and convenient pair of probes and a simple finger movement on the DFSL. The DFSL facilitates these tests, their safety and integrity, and reduces the time of many test procedures.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/983,810, filed Apr. 24, 2014. The foregoing application is incorporated by reference in its entirety as if fully set forth herein. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     TECHNICAL FIELD 
     The present invention relates generally to electrical test instrument probes, and more particularly to a dual-function switch and lead set for electrical instrument probes. 
     BACKGROUND INFORMATION AND DISCUSSION OF RELATED ART 
     Digital and analog multi-meters measure and display a wide variety of electrical functions within one meter. These functions can include AC and DC volts, amperes, ohms, frequency, temperature and many other measurements and are selectable with a switch, usually rotary, on the instrument. 
     The traditional interface between a multi-meter and the Device Under Test (DUT) is made with the use of a pair of probes, with one probe held in each hand and commonly referred to as positive and negative, with a contact on the tip of each probe being either a point or a clip (clamp, alligator) that contacts the DUT. On the plastic housing of the probe there is a plug-in socket to accommodate a single conductor flexible lead, with the other end of the lead plugging into a socket on the multi-meter. Therefore one of the probes with its lead plugs into the positive socket of the multimeter and the other probe with its lead plugs into the negative socket of the multimeter. Probes can be of many types that are commercially available from various manufacturers, but all perform the same task of connecting the meter with the DUT. 
     In traditional operation, the user must determine the required test function and pre-set the multi-meter rotary switch to the appropriate position. However, if the user wishes to change functions such as to initially read DC volts, then switch to AC volts, the user must interrupt the test and, usually with the probe in-hand, re-position the multi-meter rotary switch, then return the probe tip to the DUT. These interruptions can compromise continuity and possibly the safety of a test procedure. 
     For example, to utilize two multi-meters or one multi-meter and a resistor or capacitor would require connecting two pairs of leads (four probes) or a pair of probes and another pair of clip-leads to the DUT. This procedure can be difficult or awkward and possibly damaging to the DUT. 
     The foregoing information reflects the current state of the art of which the present inventor is aware. Reference to, and discussion of, this information is intended to aid in discharging Applicant&#39;s acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated information discloses, teaches, suggests, shows, or otherwise renders obvious, either singly or when considered in combination, the invention described and claimed herein. 
     SUMMARY OF THE INVENTION 
     The Dual-Function Switch and Lead set (DFSL) of the present invention uniquely interfaces two multimeters or one multimeter and one measurement or test instrument such as a load or signal generator. The DFSL allows two multi-meters or other electrical test tools to alternately or simultaneously be used without the necessity of removing the probe from its placement on the device under test (DUT). While the following discussion is weighted toward the use of two multimeters, the invention also applies to combinations of many other electrical testing apparatus and devices such as oscilloscopes and temperature sensors. 
     The invention provides a switch and two specialized lead wires for connection to multi-meters or other testing tools, one lead wire for the switched probe and the other for the un-switched probe. The following discussion uses the conventional negative, often called ‘ground’ or ‘common’, as the un-switched probe, but the invention can also be used with a common positive. 
     Leads on probe end: A switch unit incorporated into one of the two DFSL probe leads (usually the positive lead) that plugs into to a commercially available probe set. 
     Leads on test equipment end: Two sets of leads that connect to two multi-meters or other test equipment. 
     Positive Probe (switched): The probe switch unit contains a switch, described below, that has two leads emanating from the switch contacts as a single two conductor wire, with the two conductors branching out in a ‘T’ configuration near the multi-meter so that each conductor separately plugs into the positive socket of one of two multi-meters. 
     Negative Probe (not switched, common): The negative probe lead is a single conductor that also branches out in a ‘T’ configuration near the multi-meters. Each split-out of this single conductor plugs into the negative socket of each meter and thereby allows the negative probe, negative of meter A, and negative of meter B to all connect to each other as a common connection. 
     Switching: The probe switch allows the positive probe to be independently selected to either the positive of multi-meter A or the positive of multi-meter B, as determined by the user. The probe switch is a single pole double throw switch that operates in a ‘break before make’ mode so that the unused meter never receives a signal during switching. 
     Paralleling Over-ride: The Probe Switch in the unit also has an over-ride position that connects A and B positives together. When the over-ride position is in use, both meters are connected in parallel. Both meters therefore simultaneously receive the same signal during the over-ride mode. Paralleling Over-ride can be accomplished by an additional contact position on the Probe Switch or a separate paralleling switch. Either method of paralleling A and B positives can be momentary or maintained. The switch actuator may be embodied such as a toggle, rocker, slide, lever, or other acuator. 
     Using the DFSL in place of a traditional lead set enables (1) Two meters to display independent readings; (2) Two meters to display different ranges of the same function; (3) Use of one meter coupled with various analyzers, sensors, and electrical and electronic testing tools; (4) Testing of a battery coupled with a load; (5)“Off” position directly at probe when using only one multi-meter; and (6) Paralleling two meters for comparison, verification of reading, and calibration. 
     It is therefore an object of the present invention to provide a new and improved dual-function switch and lead set for electrical instrument probes. 
     Other novel features which are characteristic of the invention, as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings, in which preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration and description only and are not intended as a definition of the limits of the invention. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. The invention resides not in any one of these features taken alone, but rather in the particular combination of all of its structures for the functions specified. 
     There has thus been broadly outlined the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form additional subject matter of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based readily may be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     Further, the purpose of the Abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the invention of this application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. 
     Certain terminology and derivations thereof may be used in the following description for convenience in reference only, and will not be limiting. For example, words such as “upward,” “downward,” “left,” and “right” would refer to directions in the drawings to which reference is made unless otherwise stated. Similarly, words such as “inward” and “outward” would refer to directions toward and away from, respectively, the geometric center of a device or area and designated parts thereof. References in the singular tense include the plural, and vice versa, unless otherwise noted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
         FIG. 1A  is an overview of a DFSL plugged into a pair of conventional probes and two multi-meters; 
         FIG. 1B  shows a DFSL in a type of bench test that allows one probe clamped to a terminal the device under test DUT, while the other probe can be used for readings on the multi-meters; 
         FIG. 2A  shows a rocker type DFSL switch; 
         FIG. 2B  shows a toggle type DFSL switch; 
         FIG. 3A  is a DFSL schematic diagram indicating a single pole  2  position switch with position  2  (for circuit  2 ) selected; 
         FIG. 3B  is a diagram indicating the single pole  2  position switch with position  1  (for circuit  1 ) selected; 
         FIG. 5  shows two types of DFSL mountings on a dual-action type of probe. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1A through 5 , wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved dual-function switch and lead set for electrical instrument probes, generally denominated  10  therein. 
       FIG. 1A  is an overview of a DFSL  10  plugged into a pair of conventional probes P 1 , P 2  and two multi-meters M 1 , M 2  indicating the lead arrangement. The DFSL  10  provides a switch  12  and two specialized lead wires for connection to multi-meters or other testing tools, a two-conductor lead wire  14  for the switched probe P 1  and a single conductor lead wire  16  for the un-switched probe P 2 . The switch  12  has two leads emanating from the switch contacts connected to the two conductor lead wire  14 , with the two conductors separately branching out in a ‘T’ configuration near the multi-meters so that conductor  14 A plugs into the positive socket of multi-meter M 1 , and conductor  14 B plugs into the positive socket of multi-meter M 2 . The negative probe lead  16  is a single conductor that also branches out in a ‘T’ configuration near the multi-meters. Each split-out of this single conductor plugs into the negative socket of each meter and thereby allows the negative probe, the negative of meter M 1  and the negative of meter M 2  to all connect to each other as a common connection. 
     The leads at the probe ends are shown with a tab or zipper  18  (such as seen on reusable plastic bags) that can be used to adjust the lead separation to whatever distance is required by the user to reduce the tangling of leads that often happen even with conventional leads of one conductor each. 
       FIG. 1B  shows the DFSL in a type of bench test that allows one probe P 2 , usually negative, to be clamped to a terminal or component of the device under test DUT, usually a common or ground, while the other positive probe P 1  can be used for readings on the multi-meters. This can leave one hand free for setting further readings, switching a DUT, etc. The zipper  18  is also shown. 
       FIG. 2A  shows a rocker type DFSL switch  20  to select the desired circuit, with a separate button switch  22  for the over-ride position that parallels the two positions (selecting both circuits). Plug  24  releasably connects to probe socket  26 . 
       FIG. 2B  shows a toggle type DFSL switch  30 . When the toggle is set to position  30 A (e.g., circuit  1 ) a further pressing of the toggle to position  30 B will parallel the two meters or devices connected to the DFSL while held in that position. Upon release the switch reverts to position  30 A. Similarly, when the toggle is set to position  30 C (e.g., circuit  2 ) a further pressing of the toggle to position  30 D will parallel the two meters or devices connected to the DFSL while held in that position, and upon release the switch reverts to position  30 C. Numbers, color dots, or other indicia on each switch denotes the switch position, supplementing the feel of the switch to the operator. 
       FIG. 3A  is a DFSL schematic diagram indicating a single pole  2  position switch  40  with position  2  (for circuit  2 ) selected, with an over-ride paralleling button  42 , such that when the button is pressed, both circuits  1  and  2  are selected. The button does not necessarily indicate that it is a momentary switch and embodiments of the switch can be either momentary or maintained either in the switch or externally.  FIG. 3B  is a diagram indicating the single pole  2  position switch  40  set with position  1  (for circuit  1 ) selected. 
       FIG. 4  shows an embodiment of a clamp-on DFSL  50  with switch  52  and override button  54  that is not plugged directly into the probe but can be mounted or attached to the probe housing in a location convenient to the user. Alternatively, the DFSL switch can be placed in a separate housing or other structure near the multimeters, or on the test leads themselves, instead of on the probe. An extension lead  56  from the switch  50  plugs into the probe socket and another two conductor lead  58  goes to the multi-meters or test devices. 
       FIG. 5  shows two types of DFSL mountings on a dual-action type of probe  60 , and indicates that a socket plug-in type of DFSL such as rocker type switch  20  may be used with this type of plug-in probe that may have an offset socket  62 . If this is inconvenient for the user&#39;s thumb position, the housing mounted type DFSL  50  may be used. The probe shown is also of the latest dual-action type whereby the user may deploy either a point or clamp with automatic retraction of the unused tip. This further increases the testing options available by the DFSL. 
     Accordingly, the dual-function switch and lead set of this invention may be characterized as a switch and lead set apparatus for use with a pair of electrical test tools, comprising: a switch member adapted for connection to a first electrical test probe, the switch member selectively connectable to a first lead only, a second lead only, and both said first lead and said second lead combined; the first lead adapted for connection to a first polarity socket on a first electrical test tool; the second lead adapted for connection to a first polarity socket on a second electrical test tool; and a third lead adapted to connect a second electrical test probe to a second polarity socket on the first electrical test tool and a second polarity socket on the second electrical test tool. 
     Advantages of the invention include, but are not limited to: 
     1. Two meters to display independent readings: Meters may each be set to different functions and the reading will be displayed by actuating the probe switch to either position # 1  or position # 2 . The two functions can be measured alternately. Therefore a DUT having a common negative can have two separate positive probe placements and two separate meter readings can be obtained. Colors such as red and orange, and/or numbering or lettering on the switch and meter leads denote the selected meter. 
     2. Two meters to display different ranges of the same function. Multi-meters can be set to different ranges of the same function to determine the accuracy of a reading from low to high values, thus extending the range of accuracy of an instrument especially if the instrument does not have an auto-ranging feature. An example of the range switching is multi-meter # 1  set to volts and multi-meter # 2  set to millivolts. On wide-ranging voltages, the low voltage setting will provide an accuracy in millivolts that is not available on a higher range of the meter. 
     3. Use of one meter coupled with various analyzers, sensors, and electrical and electronic testing tools. The probe switch allows testing with a combination of instrument and testing device such as a load or signal input. For example, while observing changes in voltage, current, frequency, etc. with a multi-meter on position # 1 , a resistive or capacitive load can be switched on and off when connected to # 2  by actuating the Paralleling Over-Ride position. Therefore the reading can be made with and without a load or signal. This type of test is often used and accomplished by a cumbersome combination of probe and clip-leads and is therefore greatly facilitated by the DFSL. 
     4. Testing of a battery coupled with a load. The use of a multi-meter set to DC volts is often used to read battery voltages and voltage drops. Using the DFSL Paralleling Over-Ride connects a resistive load to a battery and allows the meter to observe voltage drops and voltage change with various loads and the recovery time when the load is switched-off and can be used to determine the State of Charge and health of the battery. 
     5. “Off” position directly at probe when using only one multi-meter. Using only one multi-meter if the meter probes are clamped to the DUT, the user may want to change the multi-meter switch to various positions. However, the placement of a function on the multi-meter rotary switch may entail a travel through inappropriate functions such as Volts being imposed on an Ohm position. This can result in meter damage or a blown meter fuse especially in analog meters. Therefore instead of removing one of the probe clamps, the user can switch from the connected  1  position to the open  2  position, change functions at the meter and return to # 1  at the probe. 
     6. Paralleling two meters for comparison, verification of reading, and calibration. An important asset of the DFSL and its use of only one pair of probes is the ability to easily compare the readings of two meters when each is set to the same function. By actuating the probe switch, meters may be read alternately and by using the Paralleling Over-Ride, both meters may be read simultaneously. Therefore, verification of meter accuracy can be determined if one meter&#39;s accuracy is known. If known meter is certified and calibrated traceable to a facility such as the National Institute of Standards and Testing (NIST), the unknown meter may be deemed accurate. 
     The above disclosure is sufficient to enable one of ordinary skill in the art to practice the invention, and provides the best mode of practicing the invention presently contemplated by the inventor. While there is provided herein a full and complete disclosure of the preferred embodiments of this invention, it is not desired to limit the invention to the exact construction, dimensional relationships, and operation shown and described. Various modifications, alternative constructions, changes and equivalents will readily occur to those skilled in the art and may be employed, as suitable, without departing from the true spirit and scope of the invention. Such changes might involve alternative materials, components, structural arrangements, sizes, shapes, forms, functions, operational features or the like. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention, which is defined by the appended claims.