Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-09-21
2001-05-22
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S490000
Reexamination Certificate
active
06234972
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of measuring instruments, and in particular to a mechanism used in connection with a measuring instrument which is effectively responsive and which further allows simple and convenient adjustment.
BACKGROUND OF THE INVENTION
Certain measuring devices are known, such as those found in sphygmomanometers (blood pressure cuffs) which include a pneumatic bulb which inflates a pressure chamber of an attached sleeve that is fitted over the arm or leg of a patient. A bellows assembly, responsive to changes in fluid pressure of the pneumatic bulb and the sleeve pressure chamber is positioned in a dial indicator housing. The pointer of the dial indicator is interconnected to the bellows assembly by a gage mechanism whereby inflation of the bellows causes a corresponding circumferential movement of the pointer.
Typically, these mechanisms are quite complex and intricate, and are akin in terms of their manufacture and precision to Swiss watches. For example, in one such mechanism, a pair of diaphragm springs are attached adjacent opposing ends of a spindle. A bottom end of the spindle is placed in contact with the inflatable bellows assembly and a twisted bronze band perpendicularly disposed at the top end of the spindle is connected thereto in parallel by a horizontally disposed bent spring part. As the spindle axially deflects due to the inflation of the bellows assembly, the bent spring part is caused to deflect causing the band to twist. The pointer which is attached to the bronze band is thereby caused to rotate relative to an adjacent dial indicating face.
These known mechanisms include a plurality of moving components, each having multiple bearing surfaces. Therefore, such assemblies must be manufactured with a considerable degree of tolerancing to minimize errors, thereby creating a similar level of expense in their manufacture.
In addition, any adjustments required after assembly of such mechanisms, such as to null out the pointer needle or adjust the sensitivity of the device, require substantial teardown or at least significant and undesired disassembly of the measuring device.
SUMMARY OF THE INVENTION
A primary object of the present invention is to improve the state of the art of measuring devices.
A further object of the present invention is to provide a movement mechanism for a measuring device which is simpler and more inexpensive to manufacture, but which is as reliable as known mechanisms.
Yet another object of the present invention is to provide a measuring device which is easy to adjust and which does not require teardown of the instrument if and when calibration is required.
Therefore, and according to a preferred aspect of the present invention, there is provided a movement mechanism comprising:
a shaft member having opposing first and second ends and an axis defined between said first and second ends;
axial displacement means for moving said first end of said shaft member in an axial direction; and
at least one spring member coaxially positioned relative to said shaft member axis, said spring member being attached at one end to an intermediate portion of said shaft member and attached at an opposite end to a support, wherein said displacement means causes said shaft member to translate in said axial direction, said spring member to flex, and said shaft member to rotate.
Preferably, the attachment of the spring member allows the spring to pivot or hinge during the stroke of the shaft to minimize hysteresis or other nonlinear effects.
The movement mechanism according to a preferred embodiment includes rotational position adjustment means for adjusting the circumferential location of the pointer and displacement adjustment means for preloading the spring member to thereby control the responsive amount of rotation induced over a specific axial movement of the shaft member.
Most preferably, the rotational position adjustment means includes a rotatable element coaxially aligned with the shaft, allowing an the shaft member to selectively preset or realign the pointer position. The displacement adjustment means includes a coaxial sleeve which selectively preloads the spring member, in which preloading the spring allows adjustment of the amount of angular deflection or sweep of the pointer in response to a predetermined amount of axial displacement of the shaft.
According to another preferred aspect of the present invention, there is provided a mechanism for use in a measurement device, said device comprising a housing, displacement means disposed within said housing, and indicating means responsive to said displacement means for indicating a change in a parametric value based on movement of said displacement means, said mechanism including:
a shaft member disposed in said housing between said indicating means and said displacement means, said shaft member having opposing first and second ends defining an axis therebetween; and
at least one spring member coaxially positioned relative to said shaft member axis, said spring member having a first end attached to said shaft member and a second end attached to a support, wherein said displacement means causes said shaft member to translate along said shaft axis, said spring member to flex, and said shaft member to rotate.
According to yet another preferred aspect of the present invention, there is provided a mechanism for a blood pressure gage, said gage including a bellows assembly containing a movable element disposed on one side of a housing interior, and a dial indicator face on an opposite side of said housing interior, said mechanism comprising:
a shaft member having a first end in contact with said bellows assembly and an opposite second end having a pointer attached thereto adjacent to indicia on said dial indicator face, said first and second ends defining an axis;
a spring member coaxially positioned along the axis defined by said shaft member ends, said spring member having a first end attached to an intermediate portion of said shaft member and a second end attached to a support, wherein movement of said movable element of said bellows assembly causes said shaft member to translate in an axial direction, said spring member to flex, and shaft member to rotate to allow said pointer to move circumferentially relative to said dial face.
According to another preferred aspect of the present invention, there is provided a method for calibrating a measuring device, said measuring device including displacement means disposed on one side of a housing interior, a dial indicator face disposed on an opposite side of said housing interior, and a movement mechanism disposed therebetween, said movement mechanism comprising an axially movable shaft member supported in said housing interior, said shaft member having a first end disposed adjacent said displacement means and a second end including a pointer adjacent said dial indicating face, a spring member attached at one end to said shaft member and at an opposite end to a support, said method including the steps of:
presetting the distance between said spring ends as attached to said axially movable shaft and said support to a predetermined length so as to affect the amount of rotation of said pointer for a given movement of said displacement means; and
rotating said shaft and said support to align said pointer to a null position relative to said dial indicator face.
An advantage of the present invention is that the described mechanism utilizes a minimum number of bearing surfaces and fewer moving parts than previously known systems. Furthermore, the described mechanism is simpler and more inexpensive to manufacture, yet is as reliable as other known systems.
A further advantage is that the entire mechanism can be fitted in a minimum of space and that any calibration adjustments can be made without requiring an entire teardown of the mechanism.
Yet another advantage of the present invention is that each of the elements of the described system are coaxially mounted to the shaft, making the system compact and reliable.
These an
Danna Dominic
Johnson Edward A.
Krauter Allan I.
Lia Raymond A.
Smith Timothy J.
Szmal Brian
Wall Marjama & Bilinski
Welch Allyn Inc.
Winakur Eric F.
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