Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF INVENTION
This invention relates to a probe cover, probe cover holding
mechanism and a heat sensing probe system including both, in which a thermal
chamber created by the probe cover is used to transfer heat from the probe
cover to the heat sensing element.
BACKGROUND OF INVENTION
Conventional heat sensing systems, such as those used to measure
the body temperature of mammals, often use a heat sensing element which
directly interacts with a portion of the body. In such systems the element
is exposed and susceptible to damage. In another form the sensing element
is mounted on a probe member which receives a disposable probe cover having
a tip of metal or other thermally conductive material. Typically, the tip
is large enough to provide a sufficient outer surface in the area exposed
to the body to prevent discomfort to the patient. However, when made large
to provide sufficient outer area, the resulting tips also have large mass
and so absorb greater quantities of heat from the body being monitored,
which may detract from the accuracy of the reading. The interface between
the inner surface of the tip and the heat sensing element may also be a
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source of inaccuracy: the area of the inner surface actually in contact
with the heat sensing element may vary from probe cover to probe cover and
change the heat transfer characteristics e.g. thermal time constant of the
interface. Consequently, the electronic circuits tuned to respond to a
particular optimum thermal time constant, respond unevenly with changes in
the contact between the tip and heat sensing element.
SUMP~RY OF I.~VENTION
It is therefore an object of this invention to provide an improved
probe cover for producing a positive, uniform, repeatable thermal time con-
stant with each probe cover used.
It is also an object of this invention to provide an improvedprobe cover for producing faster response time and lower heat absorption
while maintaining a relatively large outer surface area for contacting the
body whose temperature is to be monitored.
It is a further object of this invention to provide a positive
locking of the probe cover to, and ejection of the probe cover from, the
probe member.
The invention results from the realization that a probe system
having fast response time and low heat absorption, sufficient tip area, and
positive uniform repeatable thermal time constant with each probe cover can
be produced by providing a probe cover which produces a heat buffering zone
or thermal chamber, between the probe member and probe cover, which thermal
chamber includes the heat sensitive element and the tip or
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contact section of the probe cover spaced from each other in a low thermal
conductivity fluid medium for transferring heat from the contact section to
the heat sensitive element.
According to the present invention there is provided a heat
sensing probe system comprising a probe member, a heat sensitive element
sealingly engaged with and mounted on said probe member, separate and inde-
pendent of said probe member, and a disposable probe cover for mounting on
said probe member, said probe cover including a body section and a tip in-
cluding a thermally conductive contact section sealingly interconnected with
said body section, said tip being contiguous to and in sealed engagement with
said probe member for forming a thermal chamber, between said probe member
and said contact section, by said contact section and said heat sensing
element being spaced from each other and a low thermal conductivity fluid
medium for transferring heat from said contact section to said heat sensitive
element.
Other objects, features and advantages will occur from the follow-
ing description of a preferred embodiment and the accompanying drawings, in
which:
Fig. 1 is an axonometric diagram of a probe system according to
this invention;
Fig. 2 is a side elevational view of the probe system of Fig. 1
with the probe cover installed;
Fig. 3 is an enlarged sectional diagram of a probe cover according
to this invention;
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Fig. 4 is a sectional view of the probe system shown in Fig. 3;
Fig. 5 is a sectional diagram similar to Fig. 4 showing the holding
and ejection mechanism during an ejection operation;
Fig. 6 is an enlarged, exploded, axonometric view with the housing
removed, of portions of the holding and ejection mechanism shown in Figs. 4
and 5;
Fig. 7 is an enlarged, sectional diagram of a portion of a probe
system depicting the thermal chamber formed between the probe cover and the
end of the probe member according to the invention;
Fig. 8 is an enlarged, sectional diagram of a portion of an alter-
native form of probe cover according to this invention mounted on a probe
member;
Fig. 9 is an enlarged, sectional diagram of a portion of another
alternative form of probe cover according to this invention mounted on a
probe member;
Fig. 10 is an enlarged, sectional diagram of a portion of another
alternative form of probe cover according to this invention mounted on a
probe member;
Fig. 11 is an enlarged, sectional diagram of a portion of another
alternative form of probe cover according to this invention mounted on a
probe member;
Fig. 12 is a side, sectional view of an alternative probe system
and probe cover according to this invention; and
Fig. 13 is a sectional view of another alternative form of probe
cover similar to that shown in Fig. 12.
The invention may be accomplished using a disposable probe cover
for a heat sensing probe system which includes a probe member and a heat
sensing element sealingly engaged with and mounted on the probe member. The
probe cover includes a body section and a thermally conductive contact
section which is sealingly interconnected with the body section. The probe
cover is sealingly engageable with the probe member for forming a thermal
chamber between the probe member and probe cover. This sealing engagement
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between the probe cover and probe member and between the contact section
and body section of the probe cover is designed to preserve the integrity
of the thermal chamber. The thermal chamber includes the contact section
and the heat sensing element in spaced relationship to each other and is
filled with a low thermal conductivity fluid medium for transferring heat
from the contact section to the heat sensitive element. The body section
and contact section may be separate parts or they may be integral; in either
case they are sealingly interconnected.
In some forms, such as where the probe cover has an elongate or
tubular shape, the contact section may be commensurate with the end or tip
of the probe cover. Either the contact section or the body section or both
may contact the probe member to provide the seal between the probe cover
and the probe member. In those embodiments in which the probe cover is
elongate in shape the tip of the probe cover, which engages the end of the
probe member, may be tapered gently on its inner surface to produce a wedging
effect on the end of the probe member to increase the sealing force at the
thermal chamber. Either the end of the probe member or the tip or both may
be flexible.
In one probe system including such a disposable probe cover formed
of an elongate tube, the tip of which constitutes a contact section, the tip
may be formed of a high thermal conductivity material such as metal e.g.
aluminum; the tip could alternatively be formed of a material having a
relatively low thermal conductivity such as glass or the same material as
the rest of the probe cover but made thin enough so that the effective
thermal conductivity of the tip is sufficient. Also, the area of the tubular
portion of the probe cover proximate the tip may be made of material such as
polypropylene plastic having low thermal conductivity to prevent heat trans-
fer through the rest of the probe cover but the remainder of it need not be
so restricted. The probe cover holding mechanism includes a probe member
which may be, for example, a hollow tube sized to fit inside the probe cover.
At the end of the probe member there is a heat sensing element which may be
recessed or protrude from the end of the probe member. The probe member
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extends from a housing that contains the holding and ejection mechanism.
When the probe cover is properly installed on the probe member and gripped
by the holding mechanism the end of the probe member fits snugly inside of
the probe cover tip which is hollow and gently tapered. The gentle taper
on the inner surface of the tip in combination with the flexibility of either
the tip or the end of the probe member or both enables the probe member to
tighly and positively contact the tip under the holding force of the holding
mechanism. The heat sensing element at the end of the probe member is
spaced from the tip at the end of the probe cover and the hollow portion of
the tip in conjunction with the end of the probe member form a thermal
chamber in which a trapped fluid medium, such as air, acts to convey the
heat from the tip, which is exposed to the body whose temperature is to be
measured, to the heat sensing element mounted in the probe member. The
positive engagement of the end of the probe member with the tip of the probe
cover and the thermal chamber so formed provide a uniform and repeatable
relationship between the tip and heat sensing element so that the thermal
time constant of the heat sensing element remains the same with each probe
cover used.
The holding mechanism may include an actuator, at least one locking
element, and at least one ejection element. The biasing structure urges
the actuator and elements in a rearward direction overcoming the bias to
eject a used probe cover and accept a new one. There is a guide member for
guiding the elements and actuator in their forward and rearward movements
and cam members for spreading the locking elements as they are moved forward
against the force of the biasing structure and retracting those elements as
they are moved rearwardly in the direction of the bias.
In one embodiment, Fig. 1, the heat sensing probe system 10 in-
cludes a disposable probe cover 12 having a plastic tubular body 14 sealingly
interconnected with a hollow aluminum tip 16 which functions as the contact
section. Probe system 10 also includes a probe holding and ejection mecha-
nism 18 including a probe member, tube 20. Tube 20 may be a hollow metal
tube in whose end 24 a heat sensing element is contained. Monitoring current
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is supplied to the heat sensing element through cable 26 which connects to
the electronic thermometer circuit and display 28 shown in phantom.
Probe holding and ejection mechanism 18 includes an actuator
button 30, Fig. 2, slidably mounted in housing 32 to operate ejection ele-
ments 34, 36 and locking or holding elements 38 and 40 which grip probe
cover 12 at its flanged end 42 illustrated more clearly in Fig. 3. When
probe cover 12 is used with other holding and ejection mechanisms which do
not require flange 42 for their operation that flange may be eliminated.
As shown in more detail in Figs. 4 and 6 holding and ejection
mechanism 18 includes housing 32, actuator button 30, and discs 50 and 52
fixed to housing 32 at their peripheries and to probe member, tube 20, where
it passes through their respective center holes 54 and 56. Tube 20 is
slidably received in center bore 58 of actuator button 30 and a biasing
spring 60 is mounted about tube 20 between disc 50 and button 30. Spring 60
exerts a biasing force on actuator button 30 in the direction indicated by
arrow 62. Discs 50 and 52 may be fixed to tube 20 by means of an inter-
ference fit at holes 54 and 56, respectively, or through the use of adhesive
cement or other fastening means. Discs 50 and 52 may be fixed to housing
32 by means of a set screw 64 mounted in threaded bore 66. Set screw 64 is
tightened in bore 66 to bear on disc 50 and retain it in position. Disc 52
will thus also be maintained in fixed relationship to housing 32 since both
discs 50 and 52 are fixed to tube 20. Wires 26' from cable 26 may enter
tube 20 from a hole in housing 32.
The ejection elements 34 and 36 have rear detents 72, 74, Fig. 6,
which engage with channels 76 and 78, respectively, in actuator 30. Forward
detents 80, 82 are provided on ejection elements 34 and 36 for contacting
the rear portion of probe cover 12 and ejecting it from tube 20. Holding
elements 38 and 40 have rear detents 84, 86 which also are mounted in
channels 76 and 78, respectively, and forward detents 88 and 90 which have
arcuate gripping surfaces 92, 94, respectively, shaped to engage with the
circumference of body 14 of probe cover 12. Disc 50 includes notches 96
and 98 which slidably receive and guide elements 34, 38 and elements 36 and
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40, respectively, as they move with actuator 30 with and against the bias
provided by spring 60. Similar notches 100 and 102 are provided in disc 52.
Two camming members 104 are provided on element 38 and two camming members
106 are provided on element 40. Cam members 104 and 106 extend around ele-
ments 34 and 36, respectively, and in towards tube 20.
In operation, with probe cover 12 installed as shown in Fig. 4,
the force exerted by spring 60 in the direction indicated by arrow 62 is
applied through detents 88 and 90 of elements 34 and 36, respectively, to
flange 42 of cover 12. This force is sufficient to sealingly engage the
inner surface 110 of tip 16 with the outer periphery of end 24 of tube 20
so that a thermal zone 120 is formed between tip 16 and the end 24 of tube
20. To eject probe cover 12 after it is used, it is only necessary to apply
a force in the direction of arrow 112, Fig. 5, to actuator button 30, for
example, by gripping housing 32 between the index 114 and middle finger 116
and pressing on actuator 30 with thumb 118. This compresses spring 60 and
moves actuator button 30 forward on tube 20 which is fixed by means of
discs 50 and 52 in housing 32. The forward motion of actuator button 30
causes elements 34, 36, 38 and 40 to move forward guided by notches 96, 98,
100 and 102. The forward motion of members 38 and 40 causes cam members 104
and 106 to bear on notches 100 and 102 of disc 52 and spread apart the for-
ward ends of elements 38 and 40 containing detents 88 and 90. This spreading
action releases probe cover 12 so that it may be pushed off tube 20 by the
ejection elements 34 and 36.
In accordance with the invention when probe cover 12 is properly
mounted on the probe member, tube 20, Fig. 7, the end 24 of tube 20 tightly
engages the tapered inner surface 110 of hollow tip 16. Preferably, either
tip 16 or the end 24 of tube 20 or both are sufficiently resilient so that
one or both of them will bend or flex slightly by virtue of the tapering
contour of the inner surface 110 of tip 16. A temperature sensor 130 is
electrically connected to wires 26' and is sealed to tube 20 by, for example,
thermal insulating cement 132. A heat buffer zone or thermal chamber 120
is formed in the cavity created by the conjunction of hollow tip 16 and the
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end 24 of tube 20. Heat from a body to be measured flows through tip 16
and contacts the fluid medium, such as air, which is trapped in thermal
chamber 120. The motion of the air in thermal chamber 120 causes the heated
air proximate the tip 16 to come in contact with the heat sensing device 130
and quickly raise it to the temperature of tip 16 which quickly attains the
temperature of the body being monitored.
Probe cover 12 in accordance with this invention is not restricted
to the form shown in Fig. 3, as illustrated in Figs. 8-13 wherein the parts
have been given like numbers accompanied by lower case letters a, b, c, d,
e and f, respectively. For example, in Fig. 8, the tip and contact sections
are no longer commensurate: contact section 16a occupies only a small por-
tion of the tip 16 which is integral with and formed of the same material
as body 14a while contact section 16a is formed of metal. In Fig. 9, contact
section 16b and body section 14b are both formed of the same material; con-
tact section 16b is a small portion of the tip 16 formed of a much thinner
wall of the same material as the body section 14b. In Fig. 10 the tip 16 has
an even less clearly defined location with the metal contact section 16c
forming but a small portion of it. In Fig. 11 contact section 16d is formed
by a thin portion of the same material used in the rest of cover 12d. In
each of Figs. 8-11 it is apparent that the sealing engagement between the
probe cover and probe member is not limited to contact between the contact
section and probe member but can take place between portions of the tip not
including the contact section and the probe member or between the body sec-
tion and probe member.
The contact section need not be associated with any definable tip
structure. For example, in Figs. 12 and 13 where like parts have been given
like numbers accompanied by lower case letters e and f, respectively, with
respect to Fig. 7, probe cover 12e has a hollow cylindrical shape which con-
forms to the shape of probe member 20e. Thermal chamber 120e, formed by
recess 150 and probe cover 12e sealingly engaged with member 20e houses heat
sensing device 130e. The contact section 16e of cover 12e is a thinwalled
portion of the same material as the rest of cover 14e. Alternatively cover
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12f, ~ig. 13, may have a separate material for contact section 16f. In each
configuration the contact section and body section are sealed to one another
to ensure the integrity of the thermal chamber.
Other embodiments will occur to those skilled in the art and are
within the following claims:
l~hat is claimed is:
