Probe for measuring signals

Details Probe for measuring signals Probe for measuring signals

1999-03-27

2001-08-07

Metjahic, Safet (Department: 2858)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S1540PB, C324S072500, C439S482000

Reexamination Certificate

active

06271673

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to a probe that is connected to electronic measurement instruments for measuring the signals from each lead of an electronic circuit package and other electronic components mounted on a substrate. More particularly it pertains to a probe for measuring the signals of high-density mounted electronic circuit packages with narrow pitch between their leads with one hand.
BACKGROUND OF THE INVENTION
FIG. 1
is a conventional one hand held probe for measuring the signals on each lead of electronic circuit packages and other electronic components mounted on a substrate (these are collectively referred to as “DUT” below). Probe
10
has alligator clip
12
, which is coupled to a portion adjacent to a tip section
11
of the probe via cable
13
. By means of this type of probe, one of the leads (for instance, the ground terminal) is clasped and anchored by alligator clip
12
and tip section
11
is brought into contact with another lead. This type of probe is advantageous in that it is possible to keep one lead electrically connected to alligator clip
12
, and therefore the user can quickly introduce tip section
11
to several leads in succession, using one hand.
However, it is often impossible to use such a probe to clasp narrow-pitch leads of an electronic circuit package as well as the leads of electronic components mounted on a substrate at high density, therefor such probes can not perform their function in this case.
FIG. 2
shows another conventional probe
20
. This probe
20
has sub-tip section
22
next to main tip section
21
. This sub-tip section
22
is attached to the side near the main tip section
21
pivotally on its pivot so that it moves within a plane that includes the axis of the main tip section and the axis of the sub-tip section. Thus, the pointed end of this sub-tip section
22
can move up to and away from the pointed tip of main tip section
21
. This structure is suitable for probing leads with a relatively narrow pitch using one hand.
When a probe is used to measure RF signals, coaxial structure must be typically maintained in its axial position that is as close to the measuring point as possible. Therefore, the length of exposed main tip section
21
must be as short as possible in order to maintain this coaxial structure. With a design of short main chip section
21
, however, when trying to move sub-tip section
22
closer to main tip section
21
, sub-chip section
22
bumps against outer surface
23
of the probe before it gets close to main tip section
21
, resulting in that they cannot get close proximity each other. On the other hand, if the main tip section
21
is made longer to prevent the sub-tip section
22
from bumping against the outside surface
23
, in turn, a problem with the coaxial structure will occur. That is, this type of probe is designed taking into consideration whether it is more important to maintain a coaxial structure or to have a pitch that makes narrower pitch probing possible, and the designer must inevitably choose between these two alternatives. The pitch which enables this type of probe to be used for probing is limited to approximately 5 mm, therefor this type of probe is not suitable for probing leads that have a narrower pitch than that.
Furthermore, the position of the sub-tip section often changes slightly as the force applied by the user changes during probing, because the end section of the type of probe shown in
FIG. 2
is not rigid. Consequently, it is often the case that the measurements are unstable and do not have good reproducibility when this probe is used for measuring microcurrent and high-frequency signals.
Consequently, the purpose of the present invention is to present a one hand held probe for probing electronic circuit packages and various electronic components with a pitch that is narrower than the minimum pitch of leads with which the probes of prior art can cover.
Another purpose of the present invention is to present a probe for measuring signals that is flexible so that it can be adjusted by the user to any pitch as needed.
Yet another purpose of the present invention is to present a probe for measuring signals with high measurement stability and reproducibility.
SUMMARY OF THE INVENTION
The probe for measuring signals of the present invention comprises a end section that having a housing with a first and a second portions defining holes, a first tip member penetrating the first hole of the housing, and a second tip member, which is placed pivotally in the second hole of the housing so that it can turn on its pivot and is electrically insulated from the first tip member, where one end of the second tip member has a shape that is asymmetric to its pivot. The distance between the pointed end of the first tip member and the pointed end of the second tip member is determined by moving the second tip member to a desired position.
The housing of the probe is preferably electrically conductive, where an insulation member is wrapped around the first tip member so that the first tip member is electrically insulated from the housing, and the second tip member is electrically connected to the housing.
Furthermore, The probe for signal measurement according to the present invention preferably further comprises a fixation means for fixating the second tip member at a desired rotational position. For example, the fixation means preferably comprises at least one threaded third hole piercing the housing from its outer surface of the housing to the second hole, and at least one fastening knob with a thread engaging the third hole which pushes the second tip member in the second hole when rotated in one direction and moves away from the second tip member when rotated in the other direction.
Further, the end section is preferably detachable from the body of the probe. By using a coaxial connector such as an SMA connector as this detachment means, calibration is achieved using a conventional calibration standard.


REFERENCES:
patent: 2323925 (1943-07-01), Markwardt
patent: 4721903 (1988-01-01), Harsch et al.
patent: 4801434 (1989-01-01), Kido et al.
patent: 5546663 (1996-08-01), Warwicker
patent: 5555630 (1996-09-01), De Souza
patent: 06048211 (1994-03-01), None
(1) Impedance Probe Kit for HP 4194A.
(2) HP 41800A Active Probe.

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