U.S. patent application number 10/114710 was filed with the patent office on 2003-04-03 for encoding and sensing of syringe information.
Invention is credited to Hahn, Adam J., Havrilla, Joseph B., Joyce, Thomas P., Masters, Michael J., Nolan, William J. JR., Rudnick, Joelle A., Spohn, Michael A., Zaperach, Jason A..
Application Number | 20030065287 10/114710 |
Document ID | / |
Family ID | 23076223 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030065287 |
Kind Code |
A1 |
Spohn, Michael A. ; et
al. |
April 3, 2003 |
Encoding and sensing of syringe information
Abstract
A syringe for use with a powered injector to inject a fluid into
a patient includes at least a first indicator positioned on the
syringe at a predetermined axial position. The distance between a
rearward surface of the first indicator and a predetermined
position on the powered injector provides information about the
syringe configuration. The first indicator can, for example, be a
rear surface of the attachment flange. An injector system includes
a powered injector having a drive member and at least one sensor
for detecting energy. The injector system also includes a syringe
having at least a first indicator positioned on the syringe at a
predetermined axial position. The energy detected by the sensor is
determined by the axial position of the indicator when the syringe
is attached to the powered injector. The axial position of the
indicator thereby provides information about the syringe
configuration.
Inventors: |
Spohn, Michael A.; (Butler,
PA) ; Rudnick, Joelle A.; (Moon Township, PA)
; Joyce, Thomas P.; (Wilkins Township, PA) ; Hahn,
Adam J.; (Pittsburgh, PA) ; Masters, Michael J.;
(Jeannette, PA) ; Nolan, William J. JR.;
(Curtisville, PA) ; Zaperach, Jason A.;
(Springdale, PA) ; Havrilla, Joseph B.;
(Pittsburgh, PA) |
Correspondence
Address: |
GREGORY L BRADLEY
MEDRAD INC
ONE MEDRAD DRIVE
INDIANOLA
PA
15051
|
Family ID: |
23076223 |
Appl. No.: |
10/114710 |
Filed: |
April 2, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60281169 |
Apr 3, 2001 |
|
|
|
Current U.S.
Class: |
604/154 ;
604/187; 604/500; 604/67 |
Current CPC
Class: |
A61M 2205/6036 20130101;
A61M 5/007 20130101; A61M 2205/6018 20130101; A61M 2205/6063
20130101; A61M 5/142 20130101; A61M 5/14566 20130101; A61M 5/14546
20130101 |
Class at
Publication: |
604/154 ;
604/187; 604/500; 604/67 |
International
Class: |
A61M 037/00 |
Claims
What is claimed is:
1. A syringe for use with a powered injector, the syringe
comprising: at least a first indicator positioned on the syringe at
a predetermined position, the at least a first indicator defining a
surface, the distance between the surface of the at least a first
indicator and a predetermined position on the powered injector when
the syringe is in operative connection with the powered injector
providing information about the syringe configuration.
2. A syringe for use with a powered injector, the syringe
comprising: a rearward projecting member on a rear portion of the
syringe, an axial position of a rear surface of the rearward
projecting member providing information about a syringe
configuration when the syringe is attached to the powered injector;
and a positioning member operable to cooperate with the injector
when the syringe is attached to the injector to position the
rearward surface of the rearward projecting member at the axial
position.
3. The syringe of claim 2 wherein the axial position is within a
unique range of axial positions defined for the syringe
configuration of the syringe.
4. The syringe of claim 3 wherein the rear surface comprises the
rear surface of an attachment flange operable to attach the syringe
to the injector.
5. The syringe of claim 4 wherein the positioning member comprises
a flange on the syringe positioned forward of the attachment
flange.
6. A set of a plurality of syringes for use with a powered injector
to inject a fluid into a patient, each of the syringes comprising
at least a first indicator positioned on the syringe at a
predetermined position, the distance between a surface of the first
indicator and a position on the powered injector when the syringe
is in operative connection with the powered injector providing
information about a configuration of each syringe.
7. A set of claim 6 wherein the indicator is a rearward surface of
a rearward projecting member on a rear portion of each of the
syringes.
8. A set of claim 7 wherein each of the syringes further comprises
a positioning member operable to cooperate with the injector when
the syringe is attached to the injector to position the rearward
surface of the rearward projecting member at the predetermined
position.
9. The set of claim 8 wherein the predetermined position of the
rear surface of each syringe is within a unique range of axial
positions defined for the syringe configuration of that
syringe.
10. The set of claim 9 wherein the rear surface is the rear surface
of an attachment flange operable to attach the syringe to the
injector.
11. The set of claim 10 wherein the positioning member comprises
one or more flanges on the syringe positioned forward of the
attachment flange.
12. An injector system comprising: a powered injector comprising a
drive member and at least one sensor for detecting energy; and a
syringe comprising at least a first indicator positioned on the
syringe at a predetermined position, the syringe configuration that
is detected by the sensor is determined by the position of the at
least a first indicator when the syringe is attached to the powered
injector, the position of the at least a first indicator thereby
providing information about the syringe configuration.
13. The injector system of claim 12 wherein a rear surface of the
first indicator transmits energy to the sensor.
14. The injector system of claim 13 wherein the rear surface of the
first indicator comprises an energy source to transmit energy to
the sensor.
15. The injector system of claim 13 wherein the rear surface of the
first indicator comprises a surface that transmits energy to the
sensor by reflecting energy from an energy source to the
sensor.
16. The injector system of claim 12 wherein the powered injector
further comprises a contact member movably disposed in the
injector, a surface in operative connection with the contact member
transmitting energy to the sensor, the contact member being
positioned to come into contact with the first indicator when the
syringe is in operative connection with the powered injector such
that the position of the surface is determined by the axial
position of the first indicator.
17. The injector system of claim 16 wherein the surface is a rear
surface of the contact member.
18. The injector system of claim 17 wherein the rear surface of the
contact member comprises an energy source to transmit energy to the
sensor.
19. The injector system of claim 17 wherein the rear surface of the
contact member comprises a surface to reflect energy from an energy
source to the sensor.
20. The injector system of claim 17 wherein the energy is light
energy.
21. The injector system of claim 19 wherein the energy is light
energy.
22. The injector system of claim 21 wherein the reflective surface
of the contact member is a mirrored surface.
23. The injector system of claim 22 wherein the first indicator is
a rear surface of an attachment flange on a rear portion of the
syringe.
24. An injector system comprising: at least one syringe comprising
at least a first indicator positioned on the syringe at a
predetermined position, the position of the at least a first
indicator being associated with information about the syringe
configuration; and a powered injector comprising a drive member and
at least a first contact member movably disposed in the injector,
the at least a first contact member is positioned to come into
contact with the at least a first indicator when the syringe is
attached to the powered injector such that the position of the at
least a first contact member is determined by the position of the
at least a first indicator, the amount of change in the position of
the at least a first contact member as a result of contact with the
at least a first indicator being associated with syringe
configuration.
25. The injector system of claim 24 wherein at least three syringe
configurations are associated with at least three corresponding
positions of the first contact member.
26. The injector system of claim 24 wherein each syringe
configuration is associated with a range of positions of the first
contact member.
27. The injector system of claim 24 wherein the powered injector
further comprises at least one light reflective surface in
operative connection with the first contact member, the injector
system further comprising a sensor to detect light reflected from
the light reflective surface.
28. The injector system of claim 27 wherein the first indicator is
positioned on the rear surface of an attachment flange of the
syringe.
29. The injector system of claim 24 wherein the powered injector
further comprises a plurality of sensors and at least a first
shutter mechanism in operative connection with the first contact
member, each of the sensors having an on state and an off state,
the shutter mechanism comprising at least one cooperating member to
cooperate with at least one of the sensors to place the sensor in
an on state or an off state, the state of each of the plurality of
sensors providing a digital code corresponding to information on
syringe configuration.
30. The injector system of claim 29 wherein the first indicator is
positioned on the rear surface of an attachment flange of the
syringe.
31. The injector system of claim 29 wherein the shutter mechanism
comprises a plurality of cooperating members.
32. The injector system of claim 31 wherein the sensors are optical
sensors and the cooperating members are spaced opaque members
operable to block transmission of light to the sensors.
33. An injector for use with a syringe comprising at least a first
indicator positioned thereon, the position of the at least a first
indicator being associated with syringe configuration, the injector
comprising: a drive member; and at least a first contact member
movably disposed in the injector, the at least a first contact
member is positioned to come into contact with the at least a first
indicator when the syringe is in operative connection with the
injector such that the position of the at least a first contact
member is determined by the position of the at least a first
indicator, the amount of change in the position of the at least a
first contact member as a result of contact with the at least a
first indicator being associated with syringe configuration.
34. The injector of claim 33 wherein at least three syringe
configurations are associated with at least three corresponding
positions of the first contact member.
35. The injector system of claim 33 wherein each syringe
configuration is associated with a range of positions of the first
contact member.
36. The injector of claim 35, further comprising at least one light
reflective surface in operative connection with the first contact
member, the injector system further comprising a sensor to detect
light reflected from the light reflective surface, the light
detected by the sensor being dependent upon the position of the
first contact member.
37. The injector of claim 36 wherein the first indicator is
positioned on the rear surface of an attachment flange of the
syringe.
38. The injector of claim 33, further comprising a plurality of
sensors and at least a first shutter mechanism in operative
connection with the first contact member, each of the sensors
having an on state and an off state, the shutter mechanism
comprising at least one cooperating member to cooperate with at
least one of the sensors to place the sensor in an on state or an
off state, the state of each of the plurality of sensors providing
a digital code corresponding to information on syringe
configuration.
39. The injector of claim 38 wherein the first indicator is
positioned on the rear surface of an attachment flange of the
syringe.
40. The injector of claim 38 wherein the shutter mechanism
comprises a plurality of cooperating members.
41. The injector of claim 40 wherein the sensors are optical
sensors and the cooperating members are spaced opaque members
operable to block transmission of light to the sensors.
42. The injector of claim 41 wherein the first indicator is
positioned on the rear surface of an attachment flange of the
syringe and causes the first contact member to move in an axial
direction.
43. The injector of claim 42 wherein the first contact member is
slidably positioned on a bushing that is rotatable about the axis
of the syringe.
44. The injector of claim 43 wherein the shutter mechanism is
attached to the first contact member and is rotated into
cooperation with the plurality of sensor upon rotation of the
bushing to attach the syringe to the injector.
45. A method of reading information of syringe configuration from a
syringe for use with a powered injector, the method comprising:
positioning at least a first indicator at a predetermined position
on the syringe; transmitting energy from a position determined by
the indicator to a sensor on the powered injector; and measuring an
output from the sensor and correlating the output to a state
distance defined by a distance between the first indicator and a
known position on the injector, the state distance providing
information of the syringe configuration.
46. A method of reading information of syringe configuration from a
syringe for use with a powered injector, the method comprising:
positioning at least a first indicator at a predetermined position
on the syringe; contacting the indicator with at least a first
contact member movably disposed in the injector so that the
position of the first contact member is determined by the position
of the first indicator; and associating the position of the contact
member with syringe configuration.
47. The method of claim 46 wherein at least three different syringe
configurations are associated with at least three corresponding
positions of the first contact member.
48. The method of claim 47, further comprising the step of
transmitting light energy from a surface in operative connection
with the first contact member to a sensor, the light energy
measured by the sensor corresponding to the position of the first
contact member.
49. The method of claim 47 wherein a shutter mechanism in operative
connection with the first contact member moves with motion of the
contact member to a position that determines a state of each of a
plurality sensors having an on state and an off state, the state of
each of the plurality of sensors providing a digital code
corresponding to information on syringe configuration.
50. A syringe adapter for use with a powered injector, the syringe
adapter comprising: an injector attachment; a syringe attachment;
and at least a first indicator positioned on the syringe adapter at
a predetermined position, the distance between a surface of the at
least a first indicator and a predetermined position on the powered
injector when the syringe adapter is in operative connection with
the powered injector providing information about the syringe
configuration of a syringe attachable to the syringe
attachment.
51. An injector system comprising: at least one syringe comprising
at least a first indicator positioned on the syringe at a
predetermined position, the position of the at least a first
indicator being associated with information about the syringe
configuration; and an injector comprising: a drive member; a
plurality of sensors; at least a first contact member movably
disposed in the injector, the at least a first contact member is
positioned to come into contact with the at least a first indicator
when the syringe is attached to the injector such that the position
of the at least a first contact member is determined by the
position of the at least a first indicator; and at least a first
shutter mechanism in operative connection with the at least a first
contact member, each of the sensors having an on state and an off
state, the shutter mechanism comprising at least one cooperating
member to cooperate with at least one of the sensors to place the
sensor in an on state or an off state, the state of each of the
plurality of sensors providing a digital code corresponding to
information on syringe configuration.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Serial No. 60/281,169, filed on Apr. 3, 2001,
the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to encoding and sensing of
information or configuration, and, especially, to encoded syringes,
to injectors for reading encoded syringes, to injector systems
including encoded syringes and to methods of encoding and sensing
syringe information.
[0003] Critical parameters of an injection procedure are determined
by a number of variables, including, for example, syringe diameter,
syringe length, syringe material and fluid
composition/concentration. Among the affected injection procedure
parameters are fluid volume delivered, flow rate, fluid pressure,
and limits of injector piston travel. In current injector systems,
syringe size/volume is generally determined either (1) manually by
action of an operator who enters the syringe size/volume or type
into the injector software, or (2) automatically by means of
switches on the injector head which are mechanically coupled to
raised or sunken elements on the syringe. See, for example, U.S.
Pat. Nos. 5,741,232, 6,090,064 and 5,873,861, assigned to the
assignee of the present application, the disclosures of which are
incorporated herein by reference. In U.S. Pat. No. 5,873,861, the
presence or absence of one or more of detents provides a code that
is representative of syringe configuration.
[0004] Constraints of current mechanical and electrical design,
however, limit the number of such automatic detection switches.
Indeed, only limited syringe configurations are automatically
detected with present systems. Additionally, failure of certain
moving mechanisms is also a problem. For example, spillage or
leakage of contrast media can result in the failure of certain
mechanisms. Moreover, certain electrical and mechanical encoding
systems can significantly increase manufacturing costs of a syringe
and/or injector. Other currently available methods of encoding and
sensing syringe configuration include the placement of bar codes
and corresponding sensors upon the syringe and injector,
respectively, as disclosed in U.S. Pat. No. 5,997,502. Bar code
systems, however, suffer from some of the same problems as the
electromechanical systems discussed above.
[0005] As used herein, the term "syringe configuration" is used to
encompass all information about a particular syringe, including,
but not limited to, information about the mechanical properties of
a syringe (for example, material, length, diameter and/or volume)
as well as information about the contents of the syringe (for
example, fluid volume and/or composition). With the advent of new
syringes, and especially prefilled syringes, the need to accurately
encode and sense (or read) syringe configuration variables is
heightened. A powered injector to control the injection procedure
as a function of defined syringe configuration/injection parameters
can use the information on syringe configuration. Moreover, a
record of data associated with an injection procedure may be kept,
for example, to track patient treatment history and/or to satisfy
accurate billing and cost information requirements under managed
health care. A record may be maintained of information such as the
type of syringe used, the amount of contrast medium used, the type
of contrast medium used, the sterilization date, the expiration
date, lot codes, the properties of the contrast media, and/or other
clinically relevant information. Such information can be recorded
digitally for sharing with computerized hospital billing systems,
inventory systems, control systems, etc.
SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention provides a syringe for
use with a powered injector to inject a fluid into a patient. The
syringe includes at least a first indicator positioned on the
syringe at a predetermined position (for example, at a
predetermined axial position). Preferably, the distance between a
surface (for example, a rear surface) of the first indicator and a
reference position (for example, a predetermined position on the
syringe or on the powered injector when the syringe is in operative
connection with the powered injector) provides information about
the syringe configuration.
[0007] In another aspect, the present invention provides a syringe
including at least one indicator including a rearward-projecting
member (for example, an attachment flange) on a rear portion of the
syringe. The axial position of a rear surface of the
rearward-projecting member, when the syringe is in operative
connection with (for example, attached to) the powered injector,
provides information about the syringe configuration.
[0008] In a further aspect, the present invention provides a set of
a plurality of syringes for use with a powered injector to inject a
fluid into a patient. Each of the syringes includes at least a
first indicator positioned on the syringe at a predetermined
position. As described above, the distance between, for example, a
rear surface of the first indicator and a reference position such
as a predetermined position on the powered injector provides
information about a configuration of each syringe. In one
embodiment, the first indicator on each syringe is a rear surface
of an attachment flange positioned on a rearward portion of the
syringe. The axial position of the rear surface of the attachment
flange of each syringe in this embodiment provides information
about the syringe configuration of that syringe when the syringe is
in operative connection with the powered injector.
[0009] In general, the indicators of the present invention can be
an integral part of a syringe or can be attachable thereto. For
example, one or more indicators can be attachable to a syringe
through use of an adapter as known in the art. A number of such
adapters include a syringe attachment mechanism on a forward
section thereof for attachment of a syringe thereto. The adapter
also includes an injector attachment mechanism on a rearward
section thereof to attach the adapter to an injector. An adapter
can be used, for example, to attach a syringe not suitable for
direct attachment to an injector to that injector. Adapters can
also be used in the present invention to add an indicator as
described above to a syringe that is otherwise suitable for
attachment to an injector. For example, the adapter can include one
or more attachment flanges having a rear surface positioned to
provide information on syringe configuration. In general, as use
herein, the term "syringe" includes syringe/adapter
combinations.
[0010] In another aspect, the present invention provides an
injector system including a powered injector having a drive member
and at least one sensor for detecting energy. The injector system
also includes a syringe having at least a first indicator
positioned on the syringe at a predetermined position (for example,
a predetermined axial position). The sensor configuration detected
by the sensor is determined by the position of the indicator when
the syringe is in operative connection with the powered injector.
The position of the indicator thus provides information about the
syringe configuration.
[0011] In one embodiment, a rear surface of the first indicator
transmits energy to the sensor. For example, the rear surface of
the first indicator can include an energy source to transmit energy
to the sensor. The rear surface of the first indicator can also
include a surface that transmits energy to the sensor by reflecting
energy from an energy source to the sensor.
[0012] In another embodiment, the powered injector includes at
least one contact member movably (for example, slidably) disposed
in the injector. A surface in operative connection with the contact
member transmits energy to the sensor. For example, the
transmitting surface can be the rear surface of the contact member.
The contact member is positioned to come into contact with the
first indicator when the syringe is in operative connection with
the powered injector such that, for example, the axial position of
the rear surface of the contact member is determined by the axial
position of the first indicator. The rear surface of the contact
member can, for example, transmit energy to the sensor. For
example, the rear surface of the contact member can include an
energy source to transmit energy to the sensor. In another
embodiment, the rear surface of the contact member includes a
surface to reflect or redirect energy from an energy source to the
sensor.
[0013] In several embodiments, the energy transmitted in the
present invention is light energy. Reflective surfaces (for
example, a mirrored surface) can be used on the contact member or
on the indicator to transmit the light energy therefrom. The light
can, for example, be transmitted to the mirrored surface by a
transmitting fiber optic cable in communication with a light
source. The mirrored surface can transmit the light to a receiving
fiber optic cable in communication with a sensor. Sensors suitable
for use with light energy include photodiodes.
[0014] In several embodiments, the first indicator is a rear
surface of a flange or projection on a rear portion of the syringe.
The flange can, for example, also function as an attachment flange
to attach the syringe to a powered injector.
[0015] In another aspect, the present invention provides a powered
injector for use with a syringe to inject a fluid into a patient.
The syringe includes at least a first indicator at a predetermined
position. The injector includes a powered drive member and at least
one sensor to detect energy. The energy detected by the sensor is
determined by the position of the indicator when the syringe is in
operative connection with the powered injector. As discussed above,
the position of the indicator thereby provides information about
the syringe configuration.
[0016] As also described above, the injector can, for example,
include a contact member movably (for example, slidably) disposed
in the injector in which the rear surface of the contact member
transmits energy to the sensor. The contact member is positioned to
come into contact with the first indicator when the syringe is
attached to the powered injector such that the position of the
contact member is determined by the position of the first
indicator.
[0017] In a further aspect, the present invention provides an
injection system including at least one syringe having at least a
first indicator positioned on the syringe at a predetermined
position (for example, a rear surface of an attachment flange on
the rear of the syringe). As described above, the position of the
indicator is associated with information about the syringe
configuration. The injector system further includes a powered
injector including a drive member and at least a first contact
member movably disposed in the injector. The first contact member
is positioned to come into contact with the first indicator when
the syringe is attached to the powered injector such that the
position of the first contact member or the amount of change in the
position of the first contact member is determined by the position
of the first indicator and is thus associated with the syringe
configuration.
[0018] Preferably, at least three syringe configurations are
associated with at least three corresponding positions of the first
contact member. As clear to one skilled in the art, many more
syringe configuration are associable with a corresponding number of
positions of the first contact member. Each syringe configuration
can, for example, be associated with a unique range of positions of
the first contact member.
[0019] In one embodiment, the powered injector includes at least
one light reflective surface in operative connection with the first
contact member and a sensor to detect light reflected from the
light reflective surface as described above.
[0020] In another embodiment, the powered injector includes a
plurality of sensors and at least a first shutter mechanism in
operative connection with the first contact member. Each of the
sensors has an "on" state and an "off" state. The shutter mechanism
includes at least one cooperating member to cooperate with at least
one of the sensors to place the sensor in an on state or an off
state. The state of each of the plurality of sensors can, for
example, provide a digital code corresponding to information on
syringe configuration.
[0021] Preferably, the shutter mechanism includes a plurality of
cooperating members. In one embodiment, the sensors are optical
sensors and the cooperating members are spaced opaque members
operable to block transmission of light to the sensors.
[0022] The present invention provides, in a further aspect, an
injector for use with a syringe including at least a first
indicator positioned thereon. The position of the first indicator
is associated with syringe configuration. The injector includes a
powered drive member, and at least a first contact member movably
disposed in the injector as described above.
[0023] In one embodiment, the first indicator is positioned on the
rear surface of an attachment flange of the syringe and causes the
first contact member to move in an axial direction. The first
contact member can, for example, be sidably positioned on a bushing
that is rotatable about the axis of the syringe. In this
embodiment, the shutter mechanism can be attached to the first
contact member and is preferably rotated into cooperation with the
plurality of sensors upon rotation of the bushing to attach the
syringe to the injector.
[0024] In another aspect, the present invention provides a method
of reading syringe configuration information from a syringe for use
with a powered injector. The method includes (1) positioning at
least a first indicator at a predetermined position on the syringe,
(2) transmitting energy from a position determined by the indicator
to a sensor on the powered injector, and (3) measuring an output
from the sensor and correlating the output to a state distance
defined by a distance between the first indicator and a known
position on the injector. The state distance provides information
of the syringe configuration.
[0025] In still a further aspect, the present invention provides a
method of reading syringe configuration information from a syringe
for use with a powered injector. The method includes (1)
positioning at least a first indicator at a predetermined position
on the syringe, (2) contacting the indicator with at least a first
contact member movably disposed in the injector so that the
position of the first contact member is determined by the position
of the first indicator, and (3) associating the position of the
contact member with syringe configuration. Preferably, at least
three different syringe configurations are associated with at least
three corresponding positions of the first contact member.
[0026] In one embodiment, the method includes the step of
transmitting light energy from a surface in operative connection
with the first contact member to a sensor. The light energy
measured by the sensor corresponds to the position of the first
contact member.
[0027] In another embodiment, a shutter mechanism in operative
connection with the first contact member moves with motion of the
contact member to a position that determines a state of each of a
plurality sensors having an on state and an off state. The state of
each of the plurality of sensors provides or corresponds to a
digital code corresponding to information on syringe
configuration.
[0028] The encoded syringes, the injectors, the injectors systems,
and the methods of the present invention are well suited for use in
a magnetic resonance environment in which care must be taken to
prevent failure of the encoding system or device and to prevent
interference with the magnetic resonance imaging equipment.
[0029] In that regard, the strong magnetic field in a magnetic
resonance environment can adversely affect certain types of devices
such as electromechanically activated devices. Furthermore,
differences in magnetic permeability of materials within such
devices and induced eddy currents therein can affect the
homogeneity of the MRI magnetic field, generating image artifacts.
Likewise, radio frequency energy generated by certain devices can
induce unwanted artifacts upon the acquired MRI images. Such
problems are easily avoided in the syringe encoding systems,
devices and methods of the present invention. Any energy used in
the encoding systems, devices and methods of the present invention
is easily selected to prevent interference with magnetic resonance
equipment as well as interference from the magnetic resonance
equipment. For example, light energy in the infrared, visible or
ultraviolet range of the spectrum can be used. Likewise, radio
frequency energy outside of the frequency range of the MRI scanner
can be used.
[0030] Moreover, currently available syringes and injectors are
readily retrofitted to incorporate the encoding systems of the
present invention without substantial and/or expensive
modifications thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 illustrates a front perspective view of one
embodiment of an injector system of the present invention.
[0032] FIG. 2A illustrates a side, cross-sectional view of the
injector system of FIG. 1.
[0033] FIG. 2B illustrates a side, cross-sectional view of another
embodiment of a syringe of the present invention attached to an
injector.
[0034] FIG. 2C illustrates a side, cross-sectional view of another
embodiment of a syringe of the present invention attached to an
injector. FIG. 2D illustrates a side, cross-sectional view of a
further embodiment of a syringe of the present invention attached
to an injector, in which the syringe includes indicators on the
syringe barrel.
[0035] FIG. 3 illustrates the output signal of a photodiode as a
function of illuminance.
[0036] FIG. 4 illustrates the output signal of a photodiode as a
function of distance.
[0037] FIG. 5 illustrates a side, cross-sectional view of another
embodiment of an injector system of the present invention.
[0038] FIG. 6A illustrates a rear perspective view of an embodiment
of a syringe interface of the present invention in a disassembled
or exploded state.
[0039] FIG. 6B illustrates a rear perspective view of the syringe
interface of FIG. 6A in a partially assembled state.
[0040] FIG. 6C illustrates another rear perspective view of the
syringe interface of FIG. 6A in another partially assembled
state.
[0041] FIG. 6D illustrates a rear perspective view of the syringe
interface of FIG. 6A in a fully assembled state.
[0042] FIG. 7A illustrates a rear perspective view of the syringe
interface of FIG. 6A wherein the seating bushing is illustrated in
a disengaged position (left) and rotated to an engaged position
(right).
[0043] FIG. 7B illustrates a front perspective view of the syringe
interface of FIG. 6A wherein the seating bushing is illustrated in
a disengaged position (left) and rotated to an engaged position
(right).
[0044] FIG. 7C illustrates a front view of the syringe interface of
FIG. 6A wherein the seating bushing is illustrated in a disengaged
position (left) and rotated to an engaged position (right).
[0045] FIG. 7D illustrates a front perspective view of the syringe
interface of FIG. 6A with a syringe aligned for engagement
therewith and a front perspective view of an adapter for use with
the syringe interface.
[0046] FIG. 7E illustrates a rear view of the syringe interface of
FIG. 6A with a syringe connected thereto.
[0047] FIG. 7F illustrates a side, cross-sectional view of the
syringe interface of FIG. 6A with a syringe connected thereto.
[0048] FIG. 8A illustrates dimensions of one embodiment of a
shutter of the present invention as well as several states
corresponding to different shutter positions resulting from
engagement of various syringe/adapter types.
[0049] FIG. 8B illustrates engagement of the push pin or contact
pin of the syringe interface of FIG. 6A by a syringe/adapter and
tolerance analysis measurements associated with one embodiment of a
shutter.
[0050] FIG. 8C illustrates state changes associated with the
shutter and sensor embodiments of FIGS. 8A and 8B.
DETAILED DESCRIPTION OF THE INVENTION
[0051] The encoding devices, encoding systems and encoding methods
of the present invention are particularly useful in encoding
information of configuration for syringes and other pumping
mechanisms used in medical injection procedures. Several
representative embodiments of the present invention in which, for
example, light energy is used in connection with syringe encoding
are discussed below.
[0052] An embodiment of a front-loading injector system 5 of the
present invention is illustrated in FIG. 1. Injector system 5
includes a powered injector 10 and a syringe 20 for injection of,
for example, a contrast medium. As best illustrated in FIG. 1,
injector housing 30 of injector 10 preferably includes a first
drive member or piston 40 therein which cooperates with a syringe
plunger 25 (see FIG. 2A) slideably disposed in syringe 20 to inject
a fluid from the interior of syringe 20 into a patient.
[0053] As used herein to describe injection system 5 and other
embodiments of the present invention, the terms "axial" or
"axially" refer generally to, for example, an axis A around which
syringe 20 and piston 40 are preferably formed (although not
necessarily symmetrically therearound) and to directions collinear
with or parallel to axis A. The terms "proximal" or "rearward"
refer generally to an axial or a longitudinal direction toward the
end of injector housing 30 opposite the end to which syringe 20 is
mounted. The terms "distal" or "forward" refer generally to an
axial or a longitudinal direction toward a syringe tip 26 of
syringe 20 (from which pressurized fluid exits syringe 20). The
term "radial" refers generally to a direction normal to an axis
such as axis A.
[0054] Syringe 20 is preferably removably connected to injector 10
as described, for example, in U.S. Pat. No. 5,383,858, the
disclosure of which is incorporated herein by reference. In that
regard, front-loading injector 10 can include a front portion or
faceplate 60 having a first interface 62 formed therein. Piston 40
is reciprocally mounted within injector 10 and is extendible
through interface 62 in faceplate 60. Piston 40 can, for example,
include a piston flange or head 44 to assist in forming a
connection with syringe plunger 25. In the embodiment of FIG. 1,
faceplate 60 includes receiving slots 66a and 66b, which are
positioned opposite one another around interface 62. Receiving
flanges 68a and 68b are positioned opposite one another and between
receiving slots 66a and 66b and extend inwardly into interface
62.
[0055] In the embodiment of FIG. 1, the rearward end of syringe 20
includes a releasable mounting mechanism such as a pair of mounting
flanges 22a and 22b for mounting syringe 20 in a desired position
relative to the front wall of injector 10. To attach syringe 20 to
injector 10, the rearward end of syringe 20 is inserted into
injector interface 62 such that mounting flanges 22a and 22b are
inserted into receiving slots 66a and 66b, respectively. Piston
flange 44 can engage a capture mechanism on the rear of the syringe
plunger (as, for example, described in U.S. Pat. No.
5,383,858).
[0056] Once mounting flanges 22a and 22b are inserted into
receiving slots 66a and 66b, respectively, and piston 40 is in
position to be received by the plunger, the operator rotates
syringe 20 approximately 90 degrees such that mounting flanges 22a
and 22b move behind and are engaged by receiving flanges 68a and
68b, respectively. Injector 10 may include a stop mechanism (not
shown), for example, extending from at least one of the retaining
slots 68a and 68b, to prevent rotation of syringe 20 more than 90
degrees. A flange 28 on the rear of the syringe 20 forward of
flanges 22a and 22b substantially prevents injection fluid from the
exterior of syringe 20 from entering injector 10. Flange 28 also
assists in ensuring secure connection of syringe 20 to injector 10
and in positioning syringe 20 on injector 10 in a predetermined
axial position relative to injector 10. Tactile, visual or audible
feedback can be provided to the operator via, for example,
cooperating members on syringe 20 (for example, on sealing flange
28) and injector 10 to inform the operator that a secure connection
has been achieved. After securely attaching syringe 20 to injector
10, advancing piston 40 in a forward direction will apply a motive
force to plunger 25 to advance the plunger forward within syringe
20, thereby forcing the contents of syringe 20 out of syringe tip
26 into the fluid path to the patient. Retracting piston 40 in a
rearward direction will cause the plunger to move rearward within
syringe 20, thereby drawing fluid into syringe 20.
[0057] In one embodiment of the present invention, the syringe is
provided with at least one indicator element and the injector is
provided with corresponding receiver(s)/sensor(s) to provide
information on syringe configuration. A signal received by each
receiver/sensor varies depending upon the position of the indicator
element(s) upon the syringe or the distance between the indicator
element(s) and the detection/reception point(s) on the injector. In
the embodiment of FIGS. 1 and 2A, the indicator elements on syringe
20 are the rear surfaces of flanges 22a and 22b.
[0058] As illustrated, for example, in FIGS. 1 and 2A, syringe 20
can be positioned relative to injector 10 and receiver 120a and
120b in a known manner or position by abutment of the rear surface
of flange 28 with the forward surface of injector face 60. A
constant distance Y can be provided between the rear surface of
flange 28 and the forward surfaces of flanges 22a and 22b, for
example, to provide for proper and secure seating of flanges 22a
and 22b behind retaining flanges 68a and 68b (see FIG. 1, not shown
in FIG. 2A) of injector 10 when syringe 20 is securely connected to
injector 10. By varying the axial thickness (represented by X for
flange 22b) of one or both of flanges 22a and 22b, one can define
various unique states that correspond to unique syringe
configurations. As illustrated in FIG. 2A, the rear surface of
flange 22b extends beyond the rear surface of the syringe barrel by
a predetermined or known amount, while the rear surface of flange
22a is generally flush with the rear surface of the syringe
barrel.
[0059] In general, the syringes of the present invention can be
attached to an injector in any manner suitable to position one or
more indicators thereof (for example, the rear surfaces of flanges
22a and 22b) in a manner that will result in a correct reading of
syringe configuration. In the embodiment of FIG. 2A, flange 28
serves, in part, to reference the position of syringe 20 to
injector 10 and prevents syringe 20 from traveling too far rearward
during connection to injector 10. As clear to one skilled in the
art, there are many alternative manners of attaching a syringe to
an injector to properly position one or more indicators
thereon.
[0060] As shown in FIGS. 1 and 2A, the flange 28 extends around the
circumference of the syringe 20. However, the present invention
contemplates that the flange 28 may be segmented or otherwise
formed by one or more flanges, tabs or shoulder members positioned
on and extending radially from the syringe 20.
[0061] FIG. 2B illustrates a syringe 20a including two, generally
opposed attachment flanges 22aa and 22ab (not shown in FIG. 2B)
that cooperate with spaced flanges or surfaces such as flanges 66aa
and 66ab on an injector 10a to position syringe 20a at a
predetermined axial position with respect to injector 10a. Flange
22aa includes a connecting section 23aa that seats between spaced
flanges 66aa and 66ab and a rearward extending section 24aa. The
axial position of the rearward surface 26aa of section 24aa can be
varied between different types of syringes to provide information
on syringe configuration as described above. Flange 22ab (not
shown) can provide information on syringe configuration in a
similar manner.
[0062] As also clear to one skilled in the art, the indicators of
the syringes of the present invention need not be part of or
connected to an attachment flange or other attachment mechanism.
For example, FIG. 2C illustrates a syringe 20b including a
circumferential attachment flange 22b that cooperates with an
attachment mechanism 66b of an injector 10b in a manner to
removably attach syringe 20b to injector 10b. This system is
described in PCT Publication No. WO 01/37903, the disclosure of
which is incorporated herein by reference. In this embodiment, the
axial position of the rear surface 24ba of the syringe wall (which
can be varied among syringe types) can provide information on
syringe configuration as described above. Additional or
alternatively, on or more uniquely positioned indicators such as
flange or projection 24bb can be provided on a rear portion of
syringe 20b to provide information on syringe configuration as
described above.
[0063] FIG. 2D illustrates a syringe 20c attached to, for example,
injector 10c via flanges 22ca and 22cb in a manner described above
for syringe 20. In the embodiment of FIG. 2D, indicators 24ca and
24cb are positioned on the syringe barrel rather than on a rear
section of syringe 20c. Indicators 24ca and 24cb can, for example,
transmit energy to receivers 120ca and 120cb through a transmissive
flange 28c on syringe 20c.
[0064] Returning now to the embodiment of FIGS. 1 and 2A, receivers
120a and 120b can, for example, be fiber optic cables suitable to
receive light signals transmitted from the rear surfaces of
syringes 22a and/or 22b. Receiving fiber optic cables 120a and 120b
carry the received light to sensors such as photodiodes 130a and
130b. The axial position of reception points of fiber optic cables
120a and 120b are preferably known and fixed relative to flange 28.
In one embodiment, photodiodes available from Optek of Carrolton,
Tex., under product number OPF422 were used.
[0065] In the embodiment of FIGS. 1 and 2A, reflective surface 23a
and 23b (for example, a mirrored surface in the case that light
energy is used) are provided on the rear surfaces of flanges 22a
and 22b to transmit/redirect light from the rear surfaces of
flanges 22a and 22b to receiving fiber optic cables 120a and 120b.
In one embodiment, protected aluminum mirrors available from Edmund
Industrial Optics of Barrington, N.J., under product stock number
J32-354 were used. Light is directed toward mirrors 23a and 23b
such that light will be transmitted to receiving fiber optic cables
120a and 120b. In the embodiment of FIGS. 1 and 2, split fiber
optic cabling was used. Transmitting fiber optic cables 140a and
140b were arranged adjacent receiving fiber optic cables 120a and
120b to transmit light from light sources 150a and 150b (for
example, laser diodes available from Sanyo Semiconductor
Corporation of Allendale, N.J., under product number DL-3144-0) to
mirrors 23a and 23b. Suitable fiber optic cabling is available, for
example, from Omron of Santa Clara, Calif., under product number
E32-DC200.
[0066] In general, the electric signal produced by a photodiode is
proportional to the illuminance (for example, in watts/cm.sup.2) of
the radiant energy incident upon the photodiode. Indeed, the output
signal of a photodiode is generally linear with respect to the
illuminance applied to the photodiode junction as illustrated in
FIG. 3.
[0067] The illuminance of the incident radiant energy and thus the
amplitude of the electric signal (for example, measured current
and/or voltage) produced by a photodiode is indirectly proportional
to the linear distance between the light source (mirrors 23a and
23b in FIG. 2A) and the point of reception (fiber optic receivers
120a and 120b). Circuitry and/or software as known in the art can
be used to translate the measured signal into a syringe
configuration (using, for example, one or more comparison or lookup
tables). The output signal of an Optek OPF422 photodiode used in
one embodiment of the present invention is illustrated as a
function of distance in FIG. 4.
[0068] As clear to one skilled in the art, sensors such as
photodiodes 130a and 130b can be placed in direct communication
with the light source (mirrors 23a and 23b in FIG. 2A) without
intervening fiber optic cabling. However, use of fiber optic
cabling can facilitate retrofitting of existing injectors with the
encoding system of the present invention. Moreover (and as further
discussed in connection with FIG. 5 below) use of fiber optic
cabling and/or other transmitting media and the associated remote
positioning of sensors and/or energy sources assists in preventing
interference from extraneous energy sources (for example, ambient
light) and in removing sensors from areas in which spilled or
leaked injection media (for example, imaging contrast media) can
have an adverse effect upon the sensors and/or energy sources.
Moreover, fiber optic cabling can assist in positioning
sensor/light source electronics away from the magnetic field (for
example, within a shielded housing 160) of MRI equipment to reduce
interference with the MRI imaging equipment. Fiber optic cabling is
a particularly efficient means of transmitting light. Indeed,
measurements have shown that the reflection coefficient from a
dielectric interface within, for example, a high quality optical
fiber exceeds 0.9999. See, for example, Handbook of Optics,
McGraw-Hill, p. 13-6. Furthermore, as also clear to one skilled in
the art, a light or other energy source (for example, a laser or an
LED) can be positioned on the rear surface of flanges 22a and 22b
rather than using reflected energy.
[0069] The number of states or configurations detectable by the
encoding systems of FIG. 2A depends, for example, upon the
resolution of sensors such as photodiodes 130a and 130b. In
general, photodiodes are relatively sensitive to even small changes
in the distance between the transmittance point of the light and
the reception point of the light, enabling the definition of a
relatively large number of discreet states or configurations over a
relatively short distance.
[0070] The number of states or configurations detectable also
depends upon the number of indicator/sensor parings. For example,
if seven discreet states are detectable using a single
indicator/sensor pairing, 49 states are detectable using two such
pairings. Table 1 provides one embodiment of a state table for one
Optek OPF422 photodiode used in the present invention. A disengage
state and six additional states, corresponding to different lengths
X as described above, are defined by associating or correlating
discreet ranges of voltage output with those states.
1 TABLE 1 Distance (inches) Min (V) nom (V) max (V) Disengage 0.1
0.105 0.11 State 1 0.13 0.135 0.14 State 2 0.16 0.165 0.17 State 3
0.19 0.195 0.2 State 4 0.225 0.23 0.235 State 5 0.275 0.28 0.285
State 6 0.395 0.4 0.405
[0071] In addition to providing additional detectable states or
configuration, multiple indicators can be provided for calibration
or to provide data integrity. Moreover, a single sensor can be used
with multiple indicators. In certain situations, it can also be
desirable to pulse the transmitted energy to improve
detectability.
[0072] In the embodiment of FIG. 5, injector 10' includes contact
members such as push pins 220a and 220b that are slideably disposed
within injector housing 30' such that they are contacted by the
rear surfaces of at least one of flanges 22a and 22b, respectively.
Push pins 220a and 220b are preferably biased in a forward position
by, for example, springs 230a and 230b. In the embodiment of FIG.
5, the rear surfaces of push pins 220a and 220b include reflective
surfaces such as mirrors 223a and 223b as described above. Push
pins 223a and 223b are suitably positioned to reflect light from
light sources 150a and 150b exiting transmitting fiber optic cables
140a and 140b to receiving fiber optic cable 120a and 120b and
therethrough to photodiodes 130a and 130b. The output signal of
photodiodes 130a and 130b is proportional to the distance between
the rear surface of push pins 220a and 220b and receiving fiber
optic cables 130a and 130b, respectively, as described above. The
distance between the rear surface of push pins 220a and 220b and
receiving fiber optic cables 130a and 130b is directly proportional
to the axial position of the rear surfaces of flanges 22a and 22b,
respectively.
[0073] Sealing members such as O-rings 240a and 240b can be
provided to further assist in preventing spilled or leaked
injection fluid from coming into contact with the optics (or other
transmission and/or sensing media) used in the injectors of the
present invention.
[0074] Although the indicators in the embodiment of FIGS. 1, 2A and
5 of the present invention have been shown to be positioned on
flanges 22a and 22b within housing 30 or housing 30' of injector 10
or injector 10', respectively, when syringe 20 is attached to
injector 10 or injector 10', the indicators can be positioned
anywhere on syringe 20 (compare, for example, FIGS. 2A through 2D).
Moreover, energy sources other than light sources can be used in
the present invention. Any energy source/sensor or receiver pairing
in which the output of the sensor is proportional to the distance
the energy is transmitted from the indicator is suitable for use in
the present invention. For example, any waveform type energy (for
example, sonic energy or electromagnetic energy) can be used.
[0075] In case fiber optic cable is used in the above embodiments
to transmit light from an energy source to a sensor or receiver,
preferably dynamic change or deformation (for example, bending or
twisting) of the fiber optic cable is minimized. Because of the
manner in which light propagates through fiber optic cable (that
is, reflecting or bouncing between the sides of the cable as it
passes therethrough), twisting and/or bending of the fiber optic
cable changes the path of the fiber optic cable, thereby changing
the path of the light. Light beams thus may exit the cable at
different angles than for which the system was calibrated and can
cause a different amount of light to reach a receiver. If the
changes are substantial, an erroneous signal can result.
[0076] FIGS. 6A through 8B illustrate another embodiment of the
present invention in which a syringe (or, for example, a syringe
adapter as known in the art) contacts and displaces a push pin or
push pins to provide syringe configuration or information to an
injector.
[0077] As illustrated, for example, in FIGS. 6A-6D, a syringe
interface or mount 400 (shown assembled, for example, in FIG. 6D)
includes a push pin 432 that is preferably part of or formed with a
shutter mechanism 430. Alternately, the push pin 432 may be a
separate part that is connected or attached to the shutter
mechanism 430. A rubber boot or seal 420 may be placed over the
push pin 432 to prevent contrast fluid or other material from
entering the syringe interface 400 or bushing seat 450.
[0078] When assembled, the push pin 432 (and the shutter mechanism
430) protrudes in a forward axial direction from a rear surface of
a rotatable bushing seat 450. In the embodiment of FIGS. 6A-8B,
bushing seat 450 is rotatable within an interface housing 480 (see,
for example, FIG. 6C). Interface housing 480 includes slots 482a
and 482b through which, for example, flanges 822a and 822b (not
shown) of syringe adapter 800, to which syringe 700 is attached
(illustrated, for example, in FIGS. 7D and 7F), can pass to be
seated in slots 452a and 452b (see, for example, FIG. 7C) of
bushing seat 450. After seating syringe adapter 800, syringe 700
and adapter 800 are rotated approximately 1/4 turn or 90.degree.
(thereby rotating bushing seat 450) relative to interface housing
480 so that flanges 822a and 822b of syringe adapter 800 are
rotated behind and into cooperation with retention flanges 484a and
484b of interface housing 480 to removably attach syringe adapter
800/syringe 700 to syringe mount 400 as described above. Flange 828
assists in forming a secure connection of syringe adapter 800 to
interface 400 and in ensuring the proper axial position of syringe
adapter 800 relative to interface 400 as discussed above. Rotation
of bushing seat 450 relative to housing 480 as a result of the
connecting motion of syringe adapter 800 also rotates a shutter 434
of a shutter mechanism 430 into operative connection with a sensor
circuit board 500 (see, for example, FIG. 7E) as described
below.
[0079] In general, a syringe such as a syringe 700 that is not
suitable for direct attachment to syringe interface 400 or that
does not have one or more attachment flanges that are
adapted/dimensioned to provide information on syringe configuration
can be attached to syringe interface 400 through use of
intermediate adapter 800 as described above. Flange 822a, for
example, is dimensioned to provide information on the syringe
configuration of syringe 700. Adapter 800 can, for example, include
a syringe attachment mechanism 860 to attach syringe 700 thereto
via flanges 722a and 722b (not shown) of syringe 700 in a manner
described above. As known in the art, adapters have many types of
syringe attachment mechanisms that can be used to adapt a wide
variety of syringes for attachment to syringe interface 400.
Examples of syringe adapters suitable for use in the present
invention are disclosed, for example, in PCT Publication No. WO
01/08727, the contents of which are incorporated herein by
reference.
[0080] Syringe mount 400 can provide tactile, visual or audible
feedback to the operator and to injector 10 to inform the operator
that a secure connection has been achieved. For example, bushing
seat 450 can include flexing extensions 454 that cooperates with a
receptacle 486 on interface housing 480 to provide tactile and
audible feedback. In that regard, rotation of flexing extensions
454 into and out of receptacles 486 requires radial inward flexing
of flexing extensions 454. The cooperation of extensions 454 and
receptacles 486 can also provide resistance to rotation of, for
example, syringe adapter 800 or syringe 20 and bushing seat 450 in
a counterclockwise direction to release syringe adapter 800 or
syringe 20 from cooperation with retention flanges 484a and 484b
(that is, toward the position of the left side of FIGS. 7A through
7C).
[0081] As discussed above, push pin 432 is moved rearward upon
contact with syringe adapter 800 a distance determined by the axial
thickness of at least one of syringe adapter flanges 822a or 822b.
Push pin 432 is in operative connection with shutter assembly 430
such that axial motion of push pin 432 is translated to axial
motion of shutter assembly 430. In the embodiment to FIGS. 6A
through 8B, as discussed above, push pin 432 preferably includes a
cap or sealing member 420 seated thereon. The assembly of push pin
432 and shutter assembly 430 are seated in a rearward extending
well 454 formed on the rear of bushing seat 450. Shutter 434 of
shutter assembly 430 moves axially through slot 458 of well 456.
Push pin 432 and shutter assembly 430 are preferably biased in a
forward or reference position (corresponding, for example, to a
state in which no syringe is connected to syringe interface 400)
by, for example, a spring 436. Spring 436 is biased against a
shutter plate 438 that operates to secure push pin 432 and shutter
assembly 430 within well 454.
[0082] As discussed above, shutter 434 is linearly translated a
distance determined by the flange length of the engaged
syringe/adapter (see, for example, FIG. 7F, showing syringe adapter
800 of type 4 from Table 2 below attached to syringe interface
400). The movement of shutter 434 causes blocking extensions 435 of
shutter 434 to block or unblock a light source/receiver pair in
each of a plurality of sensors 510a, 510b and 510c positioned on
circuit board 500. The digital output of sensors 510a-c provides
the configuration of the syringe or adapter that is engaged on the
injector.
[0083] Syringe interface 400 provides the ability to accurately
detect (1) whether a syringe/adapter is engaged thereto as well as
(2) multiple different syringes having different flange sizes as
described above. In the embodiment of FIGS. 6A through 8B, three
sensors 510a-c are preferably used to provide a maximum of eight
combinations (2.sup.3=8) of sensor on/off states to associate with
syringe or adapter configurations. As described above, shutter 434
is rotated into communication with sensors 510a-c upon engagement
of a syringe or adapter. Thus, a disengaged state corresponds to
the state when all three sensors are on. All of sensors 510a-c are
preferably placed on the same side of shutter 434 to provide for
such rotation. Preferably, the state corresponding to all sensors
being off is not used to determine a syringe state because of
difficulties in testability. In that regard, it would be difficult
to determine if sensors 510a-c were blocked or malfunctioning in
that state. Blocking extensions 435 and the openings therebetween
are preferably sufficiently wide to ensure total activation or
deactivation of sensors 510a-c.
[0084] Table 2 provides a representative list of syringe/adapters,
corresponding flange lengths and sensor states for one embodiment
of the present invention.
2TABLE 2 Sensor State List Syringe/ Flange Adapter Length
Displacement Sensor Sensor Sensor Type (in.) (in.) 510a State 510b
State 510c State 1 0.25 0.032 Off On Off 2 0.318 0.096 Off Off On 3
0.386 0.162 On Off On 4 0.455 0.229 On On Off 5 0.515 0.288 Off On
On
[0085] FIG. 8A illustrates the dimensions of one embodiment of
shutter 434 and the states for each of the sensors/adapters of
Table 2 for a given sensor spacing.
[0086] The shutter mechanism 430 and sensors 510, in a preferred
embodiment, reliably read multiple syringe and/or adapters of
similar geometry within a given range of desired operation. A
tolerance analysis was performed on the sensing mechanism to
minimize or substantially prevent misreads. Misreads can occur, for
example, if the entire "sweet spot" of a sensor is not blocked or
unblocked with respect to a specific syringe state. In several
embodiments of the present invention, Omron EE-SX1103
photomicrosensors available from Omron Electronics, Inc. of
Schaumburg, Ill., were used as sensors 510a-c. Further information
on these sensors is provided in the Omron Electronics, Inc.
specification sheet for the EE-SX1103 photomicrosensor, the
disclosure of which is incorporated herein by reference. For those
sensors, the distance between the fully open and fully closed state
is 0.020 in. Circuit board 500 (upon which sensors 510a-c are
mounted) is adjustable in position in the direction of the movement
axis of push pin 432 to facilitate alignment.
[0087] Preferably, a mechanical calibration is performed upon
installation of sensor circuit board 500. In the embodiment of
FIGS. 8A and 8B, for example, a calibration was performed using a
slug corresponding to syringe/adapter type 1 (see Table 2) engaged
on syringe interface 400 (see FIG. 7D). During the calibration, the
top surface of top-most sensor 510a is aligned with the top of
shutter 434 as illustrated by the arrow in FIG. 8A. This position
biases the push pin/shutter assembly slightly and removed
tolerances from the system. (Several remaining tolerances
correspond to the flange thickness on the syringes or adapters, the
sensor placement and the notch/blocking extension dimensions of
shutter 434 (see FIGS. 8A and 8B)). These tolerances can contribute
to the "sweet spot" of the sensor(s) moving relative to the
notches/blocking extensions on shutter 434.
[0088] FIG. 8B illustrates representative misread plays (that is,
the distance between a sensor sweet spot and the edge of an
adjacent blocking extension 435) for a machined steel shutter
assembly having the dimensions set forth in FIG. 8A. In FIG. 8B,
the shutter displacement corresponds to a syringe/adapter of type 3
engaged within syringe interface 400. Distinct states are readily
obtained and associated tolerances indicate that misreads should
not occur. FIG. 8C illustrates test results obtained. The hatched
regions between states in FIG. 8C represent transition zones in
which sensors 510a-c were in the process of changing states.
[0089] The foregoing description and accompanying drawings set
forth the preferred embodiments of the invention at the present
time. Various modifications, additions and alternative designs
will, of course, become apparent to those skilled in the art in
light of the foregoing teachings without departing from the scope
of the disclosed invention. The scope of the invention is indicated
by the following claims rather than by the foregoing description.
All changes and variations that come within the meaning and range
of equivalency of the claims are to be embraced within their
scope.
* * * * *