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IP.com Disclosure Number: IPCOM000007556D
Publication Date: 2002-Apr-05
Document File: 7 page(s) / 21K

Publishing Venue

The IP.com Prior Art Database


A test fixture is disclosed for identifying individual wires within a multi-wire lead for identifying which wires are connected to which electrodes during the lead manufacturing process. The test fixture includes a clamp, a resister ladder network, a voltage reference source, a voltage probe, an A/D converter, a processor, and a visual/audible indicator. During manufacture, individual wires within the lead body are connected to electrodes at one end of the lead. At the other end of the lead, it is necessary to determine which wires are connected to which electrodes before the lead assembly is complete. A mechanical clamp holds down the electrode end of the lead so that each electrode is clamped at an assigned location. A plurality of resistors are connected in series to form a resister ladder. The connection node between each resistor in the resistor ladder is connected and clamped to a respective electrode at the clamped end of the lead. A voltage source of a known fixed value is applied to one end of the resistor ladder, whereby each node on the resistor ladder assumes a different voltage. The voltage appearing at the end of each wire at the unclamped end of the lead is measured. Such measurement identifies the electrode to which the wire is attached. The voltage measurement is performed through the use of an analog-to-digital converter that converts the analog voltage measured through a voltage probe to a digital voltage. The digital voltage is then input to a microcontroller. The microcontroller determines, based on the measured voltage, the particular electrode to which each wire is connected. A digital display, light, LED, buzzer, or other signaling device may be included within the test fixture to help identify the electrode to which each wire at the unclamped end of the lead is attached. This information then allows the assembly of the lead to be completed so that the wires at the unclamped or unassembled end of the lead can be attached to appropriate terminals, or other circuit elements, as a function of the electrode to which they are attached.

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The present invention relates generally to wire/electrode identifier, and more specifically it relates to a test fixture for identifying individual wires within a multi-wire lead. Even more particularly, the invention identifies which wires at one end of a multi-wire lead that is being assembled are connected to which electrodes at the other end of the multi-wire lead.

It can be appreciated that wire/electrode identifiers have been in use for years. One form of a wire/electrode identifier is simply an ohmmeter used to probe each wire or electrode of the multi-wire lead as it is assembled.

While devices such as ohmmeters may be suitable for the particular purpose to which they address, they are not as suitable for quickly identifying leads within a multi-wire lead bundle, i.e., for rapidly determining which end of a wire at one end of the multiple-wire lead belongs to which wire at the other end of the multiple-wire lead. That is, the main problem with using ohmmeters and equivalent devices as a wire/electrode identifier is that it takes too long to probe all the leads before the correct lead is found. For example, each lead has to be probed at its two correct ends in order to verify the identity and the continuity of the lead. In a bundle of 16 leads, for example, the number of times that one end of the bundle needs to be probed to identify the first lead may be as many as sixteen times. The maximum number of probes needed to identify all sixteen leads in the bundle could be as high as 135 probes. All such probing takes time. Another problem is that a general purpose ohmmeter, set on a continuity check mode (so that it sounds a tone when continuity is determined) may not function if the wires in the lead present a significant resistance. In a multi-wire implantable lead, for example, the resistance in the lead wires may be as high as 25-80 ohms, which resistance may prevent the continuity tone from being generated. Thus, in the absence of an audible tone-generator built-in to the ohmmeter, the user must hold the wires so as to make contact with the probes of the ohmmeter while at the same time visually checking the resistance readings on the scale of the ohmmeter.

In these respects, a test fixture for identifying individual wires within a multi-wire lead according to the present invention substantially departs from the difficulties associated with using the conventional concepts and designs of the prior art, and in so doing provides an apparatus that is easy and quick to use.

Summary of the Invention

In view of the foregoing disadvantages inherent in the known types of wire/electrode identifiers now present in the prior art, the present invention provides a new test fixture that quickly and accurately identifies individual wires within a multi-wire lead construction.

The test fixture herein disclosed identifies individual wires within a multi-wire lead for the...