Counterbalance mechanism for a portable radiographic imaging device - Patents.com

Abstract

A positioning system for a portable radiographic imaging device is provided, the positioning system comprising a fixed post 31 mountable to a chassis of a transport cart, the fixed post supporting an extendable post 24 that can be extended and retracted relative to the fixed post, the extendable post supporting an arm assembly that can be translated relative to the extendable post, the arm assembly being configured to support a radiographic head assembly, and a counterbalance mechanism configured to counterbalance the extendable post independent of the arm assembly and the radiographic head assembly.

Description

[Technical field]

[0001] The present invention relates to the field of radiography, and more particularly to a portable radiographic imaging device, and more particularly to counterbalancing in a portable radiographic imaging device having a collapsible column supporting an arm assembly with an adjustable height. [Background technology]

[0002] Mobile radiography equipment typically includes a transport cart that supports an extendable column that holds the radiography equipment. Summary of the Invention [Problem to be solved by the invention]

[0003] Portable radiographic imaging devices need to be mechanically balanced in all possible configurations. Today's counterbalancing mechanisms have different combinations of springs, counterweights, and feedback-controlled motors to counterbalance the radiographic imaging device over the required range of motion. Such balancing mechanisms add weight and bulk to the portable radiographic imaging device, making it difficult to operate within a hospital campus.

[0004] Therefore, there is a need for an improved counterbalancing mechanism for a portable radiographic imaging device, preferably a lighter and / or more compact portable radiographic imaging device. [Means for solving the problem]

[0005] This need is met by the subject matter of the independent claims. Optional features are set forth in the dependent claims.

[0006] According to a first aspect, there is provided a positioning system for a portable radiographic imaging device, the positioning system comprising: a fixed column mountable to a chassis of a transport cart, the fixed column supporting a telescoping column that can be extended and retracted relative to the fixed column, the telescoping column supporting an arm assembly that can be translated relative to the telescoping column, the arm assembly configured to support a radiographic head assembly, and a counterbalance mechanism configured to counterbalance the telescoping column independent of the arm assembly and the head assembly.

[0007] Providing balance to the extendable column and arm assembly independently helps reduce design complexity and implement the system by simpler means, thus allowing the system to be more compact.

[0008] The counterbalance mechanism can have a strut balancer assembly configured to counterbalance the extendable strut and another arm balancer assembly configured to counterbalance the arm assembly and the head assembly, the strut balancer assembly and the arm balancer assembly being operable independently of each other. Providing two separate balancer assemblies rather than one single assembly can help reduce the weight and footprint of the counterbalance mechanism.

[0009] The strut balancer assembly can have a first tension element attached to a first cable, and the arm balancer assembly can have a second tension element attached to a second cable, with the first cable being capable of moving independently of the second cable. In this way, the strut balancer assembly can easily operate independently of the arm balancer assembly. By "cable" we mean any suitable force transmission means, including, for example, a wire rope. The tension elements described herein specifically include spring balancers, more specifically those having a helical spring and a variable radius pulley, but the invention is not limited thereto, and it is understood that any suitable means of applying a constant force or tension can be used, including, for example, a constant force spring (e.g., combined with a fixed radius pulley). Similarly, types of springs other than helical springs can also be used, for example, tension springs. Any constant force mechanism configured to convert a force that changes with elongation into a constant force can be used in place of the variable radius pulley described herein, for example, a fuse, or a dual pulley configuration can also be used. The variable radius pulley may be implemented, for example, using a cam surface, a conical and / or helical section, or an expanding diameter mechanism.

[0010] The first tensioning element can include a first spring balancer configured to counter the weight of the extendable column, and the second tensioning element can include a second spring balancer configured to counter the weight of the arm assembly and the head assembly. The use of spring balancers can provide easy implementation of the positioning system using off-the-shelf components.

[0011] The first spring balancer can have a first helical spring and a first variable radius pulley configured to convert the force applied by the first helical spring into a constant force, and the second spring balancer can have a second helical spring and a second variable radius pulley configured to convert the force applied by the second helical spring into a constant force. Using a constant force in this manner allows the extendable post and / or arm assembly to remain in place when repositioned by a user.

[0012] The positioning system can be characterized by the absence of tension elements in the extendable post and arm assembly. In particular, the first and second tension elements can be attached to and / or at least partially contained within the fixed post. Thus, the extendable post and arm assembly can be made lighter and the weight and footprint of the positioning system can be reduced by using smaller tension elements.

[0013] One of the first and second tensile elements can be disposed substantially above the other of the first and second tensile elements to reduce the footprint of the system.

[0014] The column balancer assembly may have a first variable radius pulley and the arm balancer assembly may have a second variable radius pulley, the first and second variable radius pulleys being mounted to and only the fixed column. The first and second variable radius pulleys may also be at least partially contained within the fixed column. The positioning system may thereby be characterized by the absence of a variable radius pulley mounted to the telescopic column and / or arm assembly. In this manner, the weight of the telescopic column and arm assembly may be further reduced by mounting additional components of the balancer assembly to the fixed column.

[0015] The counterbalance mechanism can be configured to underbalance one of the extendable column, the arm assembly, and the head assembly, and overbalance the other of the extendable column, the arm assembly, and the head assembly to achieve a desired sequence of movements when the positioning system is reconfigured by a user to reposition the head assembly, such that sequencing is advantageously achieved by mechanical adjustments rather than using motorized sequencing.

[0016] Underbalance and overbalance can be achieved such that in use the portable radiographic imaging device remains statically balanced using friction supports, but brakes can nevertheless be used to lock the positioning system into a particular configuration.

[0017] The positioning system may further include an auxiliary motor configured to assist the user in repositioning the head assembly. The auxiliary motor may be configured to drive the arm assembly, for example, through a coupling to a cable of the arm assembly. The motor may be configured to receive feedback indicative of the intended movement by the user from a suitably positioned force sensor, for example, a force sensor positioned to sense a force applied by the user to reposition the radiography head assembly using the positioning system. In accordance with the present disclosure, less power is consumed by the auxiliary motor because the weight of the support is counterbalanced.

[0018] The positioning system can be configured to provide static balancing of the portable radiographic imaging device in all configurations of the positioning system.

[0019] The first embodiment can also be described with respect to two-stage independent balancing of an extendable vertical column for a portable X-ray device.

[0020] According to a second aspect, there is provided a portable radiography system comprising a positioning system as defined in any of the preceding claims and one or more of: a transport cart having a chassis to which a fixed support of the positioning system is mounted; and a radiography head assembly supported by an arm assembly of the positioning system.

[0021] The present invention may include one or more aspects, embodiments, or features, whether or not specifically disclosed in that combination, alone or in combination. Any feature or sub-aspect of one of the above aspects also applies to any of the other aspects, as appropriate.

[0022] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0023] A detailed description will now be given, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0024] [Figure 1] 1 illustrates a positioning assembly for a portable radiography device according to the present disclosure. [Diagram 2] FIG. 2 shows the positioning assembly of FIG. 1 in its uppermost configuration. [Diagram 3] FIG. 2 illustrates the positioning assembly of FIG. 1 in its lowermost configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] FIG. 1 shows a positioning assembly for a portable radiography device according to the present disclosure. The positioning assembly has a fixed column 31 supporting an extendable column 24 that can be extended and retracted vertically relative to the fixed column 31. The extendable column 24 supports an arm assembly that can be translated vertically relative to the extendable column 24. The arm assembly has a carriage 14 to which a telescopic arm 13 is attached. The arm 13 is configured to support a head assembly. For purposes of illustration, FIG. 1 shows the head assembly having an x-ray tube 12 and a collimator 11. The fixed column 31 can be mounted to the chassis of a transport cart (not shown for ease of illustration) to provide portability for the portable radiography device.

[0026] The positioning assembly is shown in a parked configuration in Figure 1. In use, the positioning assembly is movable to other configurations for proper positioning of the head assembly relative to the patient. Figure 2 shows the positioning assembly in its uppermost configuration, in which the carriage 14 is positioned at the uppermost end of its range of motion relative to the extendable column 24, which is positioned at the uppermost end of its range of motion relative to the fixed column 31. Figure 3 illustrates the positioning assembly in its lowermost configuration, in which both the carriage 14 and the extendable column 24 are positioned at the lowermost end of their respective ranges of motion.

[0027] The positioning system includes a counterbalance mechanism configured to separately balance the extendable column 24 and the arm assembly. In particular, the counterbalance mechanism includes both an independently operable column balancer assembly and a carriage balancer assembly. In the illustrated embodiment, the column balancer assembly includes a first spring balancer configured to counter the weight of the extendable column 24 (only the extendable column 24), and the carriage balancer assembly includes a second spring balancer configured to counter the weight of the arm assembly plus the weight of the head assembly (only the weight of the arm assembly plus the weight of the head assembly). The counterbalance mechanism is configured to provide static counterbalance of the device in all of its possible positioning configurations, thus assisting the user in reconfiguring the positioning system to reposition the head assembly for medical imaging.

[0028] The first spring balancer has a first helical spring 21 and a first variable radius pulley 22 configured to convert the force applied by the first helical spring 21 into a constant force. The first helical spring 21 has a first end attached to an inner surface of a fixed post 31. A second end of the first helical spring 21 is attached to a first cable that extends upward through the interior of the fixed post 31, loops over the first variable radius pulley 22, then extends downward through the interior of the extendable post 24 and is attached to a first anchor point or end 23 on the inner surface of the extendable post 24 via a first safety latch 25. The first safety latch 25 operates in response to a break in the cable to prevent the extendable post 24 from falling.

[0029] The second spring balancer has a second helical spring 32 and a second variable radius pulley 34 configured to convert the force applied by the second helical spring 32 into a constant force. The second helical spring 32 has a first end attached to the interior surface of the fixed post 31. The second end of the second helical spring 32 is attached to a second cable that extends upward through the interior of the fixed post 31, loops over the second variable radius pulley 34, then extends downward through the interior of the retractable post 24 and loops under the first fixed radius pulley. From there, the second cable extends upward again, loops over the second fixed radius pulley, then extends downward through the interior of the carriage 14 and is attached to a second anchor point 35 on the interior surface of the carriage 14 via a second safety latch 37. The first and second fixed radius pulleys are mounted on the extendable strut 24 , with the first fixed radius pulley being attached by a safety latch 36 .

[0030] It is clear that the first spring balancer functions independently of the second spring balancer. The two cables are separate and are not interconnected in any way. In this way, the extendable post and arm assemblies can be reconfigured independently of each other.

[0031] For ease of use, the desired motion sequence can be achieved by slightly underbalancing the extendable column 24 and slightly overbalancing the arm and head assemblies. This is achieved so that the device is still statically balanced using friction supports. Nevertheless, the positioning system can have brakes configured to hold the positioning system in a particular configuration during imaging or during transportation to ensure that the configuration does not shift due to external factors. For example, permanent magnet brakes can be used for this purpose. The magnitude of the underbalance and overbalance can be only a few Newtons of force (e.g., <3N). Alternatively, a counterbalance mechanism can fully counterbalance the extendable column 24 and the arm and head assemblies, and an imbalance is introduced by adding a small weight to achieve the desired motion sequence. In a typical existing positioning system, a force of 20-30N may be required to initiate a motion, so an imbalance of 3N does not affect the balancing.

[0032] The effort required to move the arm assembly downward is compensated by an auxiliary motor 33 coupled only to the first cable of the carriage balancer assembly. A force sensor 15 integrated into the handle 16 used to position the positioning system provides feedback to the motor 33. The motor assist can be used when the arm assembly is moved from the parking position (FIG. 1) to the bottom position (FIG. 2) to overcome any overbalance applied to the arm assembly.

[0033] It should be noted that according to the present invention, no tension elements are disposed on either the telescopic column 24 or the arm assembly. Thus, the first and second spring balancers can be smaller since neither of them needs to counter the weight of the other, thereby reducing the overall weight and footprint of the positioning system. Furthermore, both variable radius pulleys 22, 34 are mounted on the fixed column 31 and are contained within the fixed column 31 to the maximum extent possible, thereby further reducing the weight of the telescopic column 24 and the arm assembly. Furthermore, the second helical spring 32 can be disposed above the first helical spring 21 within the first column 31 to reduce the footprint of the system.

[0034] The applicant of the present application discloses each individual feature described herein and any combination of two or more such features solely to the extent that such feature or combination can be implemented based on the present specification as a whole in light of the common general knowledge of a person skilled in the art, regardless of whether such feature or combination solves any problem disclosed herein, and without being limited by the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features.

[0035] It should be noted that the embodiments of the present invention are described with reference to different categories. In particular, some examples are described with reference to a method, and other examples are described with reference to an apparatus. However, a person skilled in the art will understand from the detailed description that, unless otherwise specified, any combination of features belonging to one category, as well as any combination between features relating to different categories, is also considered to be disclosed by the present application. However, all features can be combined to provide a synergistic effect that is greater than the simple sum of the features.

[0036] While the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered exemplary or explanatory and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims.

[0037] The term "comprising" does not exclude other elements or steps.

[0038] The indefinite article "a" or "an" does not exclude a plurality. In addition, the articles "a" and "an" as used herein should generally be construed to mean "one or more" unless otherwise specified or unless it is clear from the context that a singular form is intended.

[0039] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0040] Any reference signs in the claims should not be construed as limiting the scope.

[0041] Unless otherwise stated or clear from the context, the phrase "A and / or B" as used herein is intended to mean all possible permutations of one or more of the listed items. That is, the phrase "X includes A and / or B" is satisfied by any of the following instances: X includes A; X includes B; or X includes both A and B.

Claims

1. 1. A positioning system for a portable radiographic imaging device, comprising: a fixed post mountable to a chassis of a transport cart, the fixed post supporting an extendable post that can be extended and retracted relative to the fixed post, the extendable post supporting an arm assembly that can be translated relative to the extendable post, the arm assembly configured to support a radiography head assembly; a counterbalance mechanism configured to counterbalance the extendable column independent of the arm assembly and the head assembly; having the counterbalancing mechanism includes a strut balancer assembly configured to counterbalance the extendable strut, the strut balancer assembly having a first tensile element attached to a first cable, the counterbalancing mechanism includes another arm balancer assembly configured to counterbalance the arm assembly and the head assembly, the arm balancer assembly having a second tensile element attached to a second cable, the first cable being capable of moving independently of the second cable such that the strut balancer assembly and the arm balancer assembly are each independently movable; there are no tension elements in the extendable post and in the arm assembly, the first and second tension elements are at least partially contained within the fixed post, and one of the first and second tension elements is disposed substantially above the other of the first and second tension elements to reduce a system footprint. Positioning system.

2. 2. The positioning system of claim 1, wherein the first tension element comprises a first spring balancer configured to counter a weight of the extendable column, the first spring balancer comprising a first helical spring and a first variable radius pulley configured to convert a force applied by the first helical spring into a constant force, and the second tension element comprises a second spring balancer configured to counter a weight of the arm assembly and the head assembly, the second spring balancer comprising a second helical spring and a second variable radius pulley configured to convert a force applied by the second helical spring into a constant force.

3. 3. The positioning system of claim 2, wherein a first end of the first helical spring is attached to an inner surface of the fixed post and a second end of the first helical spring is attached to the first cable, the first cable extending from the first helical spring upward through an interior of the fixed post, looping over the first variable radius pulley, then extending downward through an interior of the extendable post and attached to a first anchor point on the inner surface of the extendable post via a first safety latch.

4. 4. The positioning system of claim 2 or 3, wherein a first end of the second helical spring is attached to an inner surface of the fixed post, a second end of the second helical spring is attached to the second cable, the second cable extends upward from the second helical spring through an interior of the fixed post and loops over the second variable radius pulley and then extends downward through an interior of the extendable post and loops under a first fixed radius pulley, the second cable extends upward from the first fixed radius pulley and loops over a second fixed radius pulley and then extends downward through an interior of a carriage of the arm assembly and is attached to a second anchor point on the inner surface of the carriage via a second safety latch, and the first and second fixed radius pulleys are attached to the extendable post.

5. 5. A positioning system as claimed in any one of claims 1 to 3 or claim 4 which relies on claim 2, wherein the column balancer assembly has a first variable radius pulley and the arm balancer assembly has a second variable radius pulley, the first and second variable radius pulleys being attached to the fixed column and only to the fixed column.

6. 6. The positioning system of claim 5, wherein there are no variable radius pulleys attached to the extendable column and there are no variable radius pulleys attached to the arm assembly.

7. 4. The positioning system of claim 1, wherein the counterbalance mechanism is configured to underbalance one of the extendable column, the arm assembly, and the head assembly, and to overbalance the other of the extendable column, the arm assembly, and the head assembly to achieve a desired movement sequence when the positioning system is reconfigured by a user to reposition the head assembly.

8. The positioning system of claim 7 , wherein the underbalance and overbalance are achieved such that, in use, the portable radiographic imaging device remains statically balanced using the friction support.

9. The positioning system of claim 7 , wherein the magnitude of the underbalance and overbalance is 3N or less.

10. 4. The positioning system of claim 1, further comprising an assist motor configured to assist a user in repositioning the head assembly, the assist motor configured to receive feedback from a force sensor positioned to detect a force applied by a user to reposition the radiography head assembly using the positioning system.

11. 4. A positioning system according to claim 1, configured to provide static balancing of the portable radiographic imaging device in all configurations of the positioning system.

12. A positioning system according to any one of claims 1 to 3; one or more of: a transport cart having a chassis to which the fixed posts of the positioning system are attached; and a radiography head assembly supported by the arm assembly of the positioning system; A portable radiography system comprising:

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