Non-contact locked terminal tester

A method of determining the quality of insertion of an electrical terminal includes the steps of capturing the sound associated with insertion of the terminal. The terminal is typically inserted into a connector associated with a wire harness. By capturing the sound, the system is able to compare the captured sound to an expected sound. If the captured sound differs from the expected sound then a determination is made that the terminal is not properly inserted.

BACKGROUND OF THE INVENTION 
This invention relates to a method and apparatus for testing the quality of 
insertion of an electrical terminal. 
In the prior art, many electrical components are still assembled manually. 
As one example, wire harnesses are formed by manually arranging wires to 
various locations on a jig. The wire terminal is also locked into an 
electrical connector. Many terminals and associate wires are locked into a 
typical connector. When the wire harness is fully assembled and the 
connector has received all of the designed terminals some method of 
testing the quality of terminal insertion is necessary. 
Typically, the prior art has utilized some form of electrical test to 
ensure that all of the terminals do communicate electricity to or from the 
connector. However, the typical connectors receive a terminal in a sliding 
connection. In the past, a terminal may sometimes be only partially 
inserted into the connector body. In some cases, a partially inserted 
terminal may be inserted sufficiently such that it will communicate 
electrical signals. Thus, the prior art electrical tests have not been 
able to always identify an improperly inserted terminal. 
If an improper terminal is not discovered at this test stage, then it is 
possible the wire harness could be assembled into a vehicle. 
SUMMARY OF THE INVENTION 
In a disclosed embodiment of this invention, a method is utilized for 
capturing the sound as the terminal is inserted into the connector. The 
sound will have a predictable pattern if the terminal is properly and 
fully inserted into the connector. The captured wave is compared to the 
features of an expected wave by a control system. If the captured wave 
differs significantly from the expected wave, then the terminal is 
identified as being faulty. 
In a disclosed embodiment of this invention, a microphone is associated 
with a jig for holding the connector when the terminals are being 
inserted. The sound of the terminal being inserted into the connector is 
captured as each terminal is inserted. An analog sound signal passes 
through a filter to remove unwanted noise. The signal then passes through 
an analog to digital converter, and then to a control unit such as a CPU. 
Preferably, the control communicates with a memory in which an expected 
wave is compared with the captured wave. The control unit is also able to 
then make a determination of whether the terminal has been properly 
inserted based upon the comparison. The control unit is further capable of 
communicating with outputs such as a speaker to replay the sound, or a 
visual display at which the captured wave can be displayed to an operator. 
In embodiments of this invention, the control may serially capture all of 
the insertion sounds from the terminals in a single connector and then 
compare all of the captured waves to expected waves prior to determining 
the quality of each terminal insertion. Alternatively, each terminal can 
be compared to the expected wave as it is inserted. 
Within a single connector, there may be different sizes or types of 
terminals, and there may be different expected waves. Thus, the control 
must be able to predict the expected type of terminal being inserted at 
any particular time have the proper expected sound wave. 
These and other features of the present invention can be best understood 
from the following specification and drawings, the following of which is a 
brief description.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
FIG. 1 shows a system 20 for testing the quality of the terminals 22 
inserted into a connector 24. Connector 24 and terminals 22 may be of the 
type typically associated with a wire harness. As shown, a jig 25 holds 
the connector as the terminals 22 are inserted into the connector 24. 
A microphone 26 is positioned adjacent to the jig such that it can capture 
the sound wave as each terminal 22 is inserted in the connector 24. The 
waves are typically a plot of volume against time. The wave is compared to 
expected waves by a control 28. The control 28 may store the expected 
waves in a random access memory 30. The expected waves may be taught by 
manually, and fully, inserting terminals. Random access memory 30 may also 
store the captured signals, should the control be of the sort which will 
capture all of the terminal insertion signals for a particular connector 
before comparing the sounds to the expected signals. 
As shown, a filter 32 receives the raw analog signal from the microphone 
26. Filter 32 removes unwanted noise, etc. 
The analog signal then passes to an analog to digital converter 34 which 
changes the signal into digital form. The control CPU 28 receives the 
digital signal, and in conjunction with memory 30, compares the signal to 
an expected signal. 
The control 28 also communicates with an output circuit. As shown, the 
signal may pass through a digital to analog converter 36, and back through 
the filter 32. A second filter may be utilized for the outlet rather than 
a single filter 32. The signal then passes to an output mechanism where it 
can be displayed to the operator. As one example, speaker 38 may play the 
captured sound for the operator. Alternatively, a visual display 40 may 
display the wave and compare it to the expected waves. In the illustrated 
example, the wave 42 associated with the insertion of one terminal 24 is 
shown. High and low expected extremes 44 and 46 are shown. The particular 
analysis of this system may be that if the captured wave 42 does not cross 
both boundaries 44 and 46, then the terminal is not fully inserted. 
Each type of terminal will have its own expected targets. Thus, as an 
example, a second wave 48 associated with a terminal of a different sort 
than the wave 42 terminal, may have its own boundaries 50 and 52, which 
are distinct from boundaries 44 and 46. 
The use of simple boundaries which are to be crossed by the wave for the 
terminal to be deemed as being fully inserted is a simplified 
illustration. In practice, it may be that the entire wave is compared to 
an expected wave. In such cases, some margin of error for the wave is 
typically provided. Further, only a component of the captured sound need 
be used. As an example, if the only comparison is to boundaries, then only 
the extremes of the sound need be captured. 
As stated above, the mere comparison to boundaries is a simplified 
approach. The actual system might use a more sophisticated test such as 
calculating the area under the wave, and comparing that area to an 
expected area. Some margin of err would be allowed for the terminal to be 
assumed to be properly inserted. However, should the area differ beyond 
this margin of error, then the terminal will be identified as being 
improperly inserted. In addition, the actual frequencies of the captured 
sound could be compared to expected frequencies. 
FIG. 2 again shows the simplified comparison of a wave 54 to a target wave 
55, and to the boundaries 44 and 46. Since the wave 54 does not cross the 
boundaries 44 or 46, then the wave 54 may be associated with the terminal 
which is faulty. As also shown, the target wave 55 would have a much 
greater area underneath its curve than the area under the wave 54. This 
would also lead to the indication that the particular terminal has not 
been properly inserted. 
The method can be operated such that as each terminal is inserted feedback 
is provided to the operator on the propriety of that terminal insertion. 
Alternatively, the system may wait until all of the terminals in a 
connector are inserted, before displaying to the operator any terminals 
which would appear to be improperly inserted. The control must be able to 
predict the type of terminal being inserted at each time. Thus, if a 
connector is to receive two types of terminals such that there would be 
two different types of expected signals, then those terminals and their 
order of insertion must be known to the control. FIG. 3 shows a compressed 
set of captured signals from a twelve terminal connector. As an example, 
signals 2 and 3 correspond to the same type terminal. Signal 10, as an 
example, is of a distinct type terminal. 
The exact electrical details associated with this invention are well within 
the scope of a worker of ordinary skill in the art. The invention may 
provide the wave form by a sampling rate of 16-44 kHz. Other sample rates 
may be utilized. The digital analog converter may have an audio band width 
of between 8 and 22 kHz. The analog digital converter may transform the 
wave into an 8 bit data signal. Again, the exact electrical details may 
vary, the main features of this invention are the use of the comparison of 
the captured sound wave to compare to an expected sound wave and making a 
prediction about whether the terminal has been properly inserted. 
A preferred embodiment of this invention has been disclosed, however, a 
worker of ordinary skill in the art would recognize that certain 
modifications would come within the scope of this invention. For that 
reason, the following claims should be studied to determine the true scope 
and content of this invention.