Electric heating – Metal heating – Cutting or disintegrating
Utility Patent
1999-03-24
2001-01-02
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
Cutting or disintegrating
Utility Patent
active
06169260
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a needle disposal apparatus which melts and disposes of a needle such as a used needle of a hypodermic syringe.
A conventional needle disposal apparatus is often of a fixed electrode type, as shown in FIG.
9
. The needle disposal apparatus of this type has fixed electrode plates
21
and
22
, between which a given voltage is applied by a power source
23
. Heat is produced in a used needle
24
of a hypodermic syringe
25
by passage of electrical current between the electrode plates
21
and
22
through the needle
24
, thereby melting the needle
24
. However, contact areas
21
a
and
22
a
in the electrode plates
21
and
22
, with which the needle
24
is in contact, become oxidized to form an oxide of high resistance, resulting in a disadvantage that the needle disposal apparatus loses its melting action after disposal of several tens to several hundreds of needles.
To overcome this disadvantage, a needle disposal apparatus having rotatable electrode rollers
36
and
41
as shown in
FIG. 10
is developed. In
FIG. 10
, a reference numeral
31
denotes a battery as a power source,
32
denotes a power switch with a breaker,
33
denotes a fastened terminal, and
34
denotes an insulator bushing. Further, reference numerals
35
and
44
denote contact blades which are disposed in contact with contact areas on the rotary shafts
38
and
43
supporting the electrode rollers
36
and
41
. The blades
35
and
44
are formed of phosphor bronze with a thickness of 0.3 mm.
The upper electrode roller
36
is mounted on a case
50
(shown by two-dotted broken lines) by a pair of bearings
37
disposed on the opposite sides thereof so as to be rotatable and is electrically insulated from the case
50
. On its one end, the rotary shaft
38
of the upper electrode roller
36
is fixedly provided with a gear
39
b
which is engaged with a gear
40
a
on a shaft of a motor
40
so as to be rotated in a direction A
1
by driven power transmitted from the motor
40
. The rotary shaft
38
of the upper electrode roller
36
is also provided with a gear
39
a
which is engaged with a gear
41
a
fixedly mounted on the rotary shaft
43
of the lower electrode roller
41
. Thus the lower electrode roller
41
is rotated by the driven power transmitted from the motor
40
in a direction A
2
opposite to the direction A
1
.
The lower electrode roller
41
is rotatably supported on the case
50
by a pair of bearings
42
. The rotary shaft
43
of the lower electrode roller
41
has a contact area on one of its axial ends which is disposed in contact with the contact blade
44
which is connected to a battery terminal of the opposite polarity from the terminal which is connected to the contact blade
35
. Each electrode roller
36
and
41
is formed of a brass cylindrical member with chrome plating.
FIG. 11
illustrates a needle to be disposed of and electrode rollers in the apparatus of FIG.
10
. In
FIG. 10
, when the used needle
24
is brought into contact with both the upper electrode roller
36
and the lower electrode roller
41
, current of a high magnitude flows through the needle
24
. Therefore, the stainless steel needle is heated to cause its melt-down.
It is possible that oxide films of high resistance be formed on the surfaces of the upper electrode roller
36
and the lower electrode roller
41
or that a contamination may be deposited on the needle
24
to interface with the current conduction therethrough. However, even in such instance, the surface of the needle
24
is mechanically scrubbed by the electrode rollers
36
and
41
which are rotating, whereby such oxide films are removed. Thus the arrangement of
FIG. 10
eliminates a failure of melt-down which may be caused by oxide film as in the arrangement of FIG.
9
.
However, the needle disposal apparatus having rotating electrodes mentioned above still suffers from a number of shortcomings as indicated below.
1. A heating which occurs between the contact blade
35
(or
44
) and the contact area of the rotary shaft
38
(or
43
) may result in a loss of resilience in the phosphor bronze.
2. As the contact area of the rotary shaft
38
(or
43
) becomes abraded and oxidized, its fragments may be deposited around the contact area of the rotary shaft
38
(or
43
) to cause a poor contact. A contact formed between dissimilar metals is essentially liable to cause a poor contact. The fragments are in turn scrubbed as may be typified by abrasion due to minimal sliding motion to produce insulating oxides, representing insulative dregs, which then find their way into the contact region to increase a resistance of contact, contributing to a further heating. This ultimately results in a poor contact.
3. A hypodermic needle has a varying thickness from 16 G (having a diameter ø of 1.6 mm) to 30 G (having a diameter ø of 0.3 mm). Where the needle is inserted between the pair of electrode rollers
36
and
41
as in the prior art practice where the electrode rollers
36
and
41
abut laterally against the needle
24
, an accommodation for a varying thickness of the needle has been unsatisfactory. An accommodation employed with the arrangement of
FIG. 10
has been to provide a variation in the thickness or the diameter of the upper electrode roller
36
from location to location. However, with this technique, a user must slide the needle in a direction B
1
of an axis of the electrode roller
33
to determine the position where it is inserted manually in accordance with the thickness thereof, which is cumbersome. If the electrode rollers
36
and
41
are abraded, a satisfactory contact is no longer ensured, with consequence that the useful life of the electrode rollers
36
and
41
is limited to the order of several thousands of needles which can be disposed of.
In addition, if a needle having an increased thickness is strongly and rapidly urged into the interstice between the pair of electrode rollers
36
and
41
, there results an insufficient amount of heating to melt down the needle, which would then be flexed to be fitted between the upper roller
36
and the lower roller
41
. In worst cases, the needle may not be withdrawn from between the electrode rollers
36
and
44
.
4. Both the upper and the lower electrode rollers
36
and
44
are of an equal diameter and are driven to rotate at an equal rotational speed, thus presenting a substantially equal resistance of contact. This resulted in a failure to melt down the needle at a definite position thereon. In other words, when viewed from the standpoint of the quality of disposal, it is difficult to keep the length of the needle which remains without being melted down constant. Thus if the needle is melted down at the point of contact with the lower electrode roller
41
, the remaining length will be lower. By contrast, if the needle is melted down at the point of contact with the upper electrode roller
36
, the length of the residue will be relatively short, but a plastic body of the syringe will be scorched to cause a stench.
5. A needle disposal apparatus is constructed on the premise that it melts down the hypodermic needle. It is to be noted however that needles are of varying types, including one which has its surface coated with a plastic. Such a needle does not allow a current conduction and hence cannot be melted down. If such a needle is inserted into the apparatus, it will be drawn into the space between the electrode rollers
36
and
41
as the latter rotate without being melted down, thus causing a locked condition of the motor. If the battery is nearly exhausted, the breaker cannot be operated and thus the motor is also likely to be locked.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a needle disposal apparatus which overcomes various shortcomings mentioned above by enabling a disposal in a facilitated and reliable manner.
According to one aspect of the present invention, a needle disposal apparatus for melting a needle to be disposed of by passage of ele
Akutsu Naoji
Ota Yukio
Evans Geoffrey S.
Oki Data Corporation
Rabin & Champagne PC
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