Geometrical instruments – Distance measuring – By flexible tape
Reexamination Certificate
2002-11-21
2004-06-22
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Distance measuring
By flexible tape
C033S761000
Reexamination Certificate
active
06751883
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of Invention
The present invention relates to a tape measure, and more particularly to a reel rotation mount arrangement equipped with friction reduction means for tape measure, which is capable of not only substantially supporting a tape reel via a supporting axle but also enhancing the rotational movement of the tape reel by means of the friction reduction device.
2. Description of Related Arts
Retractable tape measures have been commercially used for many years. As shown
FIG. 1
, a conventional tape measure comprises a housing A
1
having an entrance and two opposed sidewalls A
11
, a reel A
2
rotatably mounted in the housing A
1
, an elongated measuring blade A
3
having one end attached to the reel and another stopper end extending out of the housing A
1
through the entrance, and a retracting means A
4
for winding up the measuring blade A
3
in a coil rolled manner in the housing A
1
while the stopper end of the measuring blade A
3
being blocked at the entrance of housing A
1
. One of the most distinctive features of the tape measure is that the measuring blade A
3
can be pulled out from the housing A
1
for measuring purpose and automatically retracted back into the housing A
1
via the retracting means A
4
.
In order to rotatably support the reel A
2
in the housing A
1
, the tape measure further comprises a supporting unit comprising two hollow supporting shafts A
5
integrally and inwardly extended from the two sidewalls A
11
of the housing A
1
respectively to rotatably support the reel A
2
. Accordingly, since the housing A
1
is usually made of plastic to reduce the cost of the tape measure, the plastic made supporting shafts A
5
cannot rigidly support the reel A
2
. Especially when the pulling force and the retracting force from the measuring blade A
3
are exerted on the supporting shafts A
5
, the supporting shafts A
5
will be broken easily. Moreover, since both the supporting shafts A
5
and the reel A
2
are made of plastic, the frictional force between the supporting shaft A
5
and the reel A
2
will generate heat and wear away the supporting shafts A
5
, so as to deteriorate the smooth operation of the measuring blade A
3
.
For reducing the frictional force of the tape measure, a bearing A
6
is mounted between the supporting shafts A
5
and the reel A
2
since the bearing A
6
is commonly used as a friction reduction device between the two rotational surfaces to reduce the friction force therebetween. However, there are several drawbacks for the tape measure when the bearing unit A
6
is employed therewith.
Since the contacting area between the supporting shafts A
5
and the reel A
2
is constructed as an outer circumference surface of each supporting shaft A
5
, the bearing A
6
must be radially extended to cover the contacting area in order to enhance the rotational movement of the reel A
2
. In other words, a bigger interior of the housing A
1
is required to fit the bearing A
6
therein, so that the size of the housing A
1
must be substantially increased, so as to reduce the portability of the tape measure.
In addition, even though the bearing A
6
can enhance the smooth in and out sliding movement of the measuring blade A
3
with respect to the reel A
2
, the structure of the bearing A
6
will cause a vibration force on the measuring blade A
3
. It is because two sides of the reel A
2
are rotatably supported by the supporting shafts A
5
respectively, when the measuring blade A
3
is pulled out from or retracted back to the housing A
1
, an uneven pulling or retracting force is created at two sides of the reel A
2
. As a result, the sliding operation of the measuring blade A
3
is deteriorated by the vibration force.
Moreover, the bearing A
6
will not only increase the cost of the tape measure but also complicate the structure of the tape measure so as to increase the manufacturing cost thereof. Therefore, the conventional tap measure cannot provide a rigid structure to support the reel and a smooth sliding operation of the measuring blade A
3
while being cost effective.
Another drawback of the conventional tape measure is that the retracting means A
4
is easily broken by the in and out movement of the measuring blade A
3
. When a portion of the measuring blade A
3
is pulled out from the housing A
1
through the entrance thereof, a retracting force is restored in the retracting means A
4
for automatically retracting the measuring blade A
3
back into the housing A
1
when the pulling force on the measuring blade A
3
is released. However, when the measuring blade A
3
is pulled outwardly, the weight of the measuring blade A
3
will be dropped downwardly and force the measuring blade A
3
in contact with the housing A
1
at the entrance. Therefore, the retracting means A
4
must provide enough retracting force to not only pull back the measuring blade A
3
into the housing A
1
but also compensate the friction force between the measuring blade A
3
and the housing A
1
. In other words, due to the friction force, the retracting means A
4
will be easily worn out after a period of continuous use.
SUMMARY OF THE PRESENT INVENTION
A main object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, which is capable of not only substantially supporting a tape reel via a supporting axle but also enhancing and smoothing the rotational movement of the tape reel by means of the friction reduction device.
Another object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, which can substantially smoothen the rotational movement of the tape reel and prevent, especially during the retraction of the measuring blade. Therefore, the retraction power of coil spring can be reduced correspondingly and thus the width of the coil spring can be reduced, for example from 30 mm to 22 mm for a 35 feet tape measure, so that the weight, the size and the manufacturing cost of the tape measure can be largely reduced in comparison with the conventional tape measure.
Another object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, wherein two ends of the supporting axle are securely mounted to the housing to rigidly support the tape reel in a rotatably movable manner.
Another object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, wherein the friction reduction device is mounted between the housing and the reel for enhancing the smooth rotational movement of the tape reel so as to minimize the vibration force of the measuring tape during operation.
Another object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, wherein the tape measure does not require altering the original structural design in order to incorporate with the friction reduction device. In other words, the housing can be constructed to have a compact size to enhance the portability of the tape measure. In addition, the conventional tape measure is capable of employing the friction reduction device to enhance the rotational movement of the tape reel.
Another object of the present invention is to provide a reel rotation mount arrangement equipped with friction reduction means for tape measure, wherein no expensive or complicated structure is required to employ in the present invention in order to achieve the above mentioned objects. Therefore, the present invention successfully provides an economic and efficient solution not only for providing a rigid configuration for supporting the tape reel but also for enhancing the rotational movement of the tape reel.
Accordingly, in order to accomplish the above objects, the present invention provides a tape measure, comprising:
a housing assembly comprising a casing having two opposed sidewalls, a receiving cavity forming therebetw
Chan Raymond Y.
David and Raymond Patent Group
Fulton Christopher W.
LandOfFree
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