Patent Description:
Movable rack arms often benefit from a counterbalance spring that prevents the arm from moving too easily in a given direction. For example, it is often useful for surgical equipment to be attached to movable rack arms so that it can be manipulated during surgery, for example to be brought into or moved out of a surgical field, or moved with respect to the patient or surgeon. However, it is also often important for the movable rack arm and the attached equipment to move too readily, as the surgery might be disrupted or the patient might suffer an injury. A counterbalance spring is often used to prevent a movable rack arm and attached equipment from moving too easily, for example, in response to an accidental bump. Reference is made to the documents <CIT>, <CIT>, <CIT>, <CIT>, and <CIT> as relating to the state of the art.

The present disclosure relates to a surgical console including a base, a tray or screen assembly, a parallelogram arm, and a movable rack arm assembly attached to the base, the tray or screen assembly, or the parallelogram arm. The movable rack arm assembly includes a cam housing including an internal rack arm guide pin and an axle, a circular gear including circular gear teeth and mounted on and rotatable about the axle, a rack arm, a cam, and a spring assembly. The rack arm includes a rack arm attachment attached to the base, the tray or screen assembly, or the parallelogram arm, a rack gear including rack gear teeth, and a rack arm track associated with the internal rack arm guide pin to hold the rack gear teeth engaged with the circular gear teeth as the rack arm is extended or retracted with respect to the cam housing such that the circular gear is rotated about the axle as the rack arm is extended or retracted. The cam is attached to the circular gear such that the cam rotates in a corresponding manner when the circular gear rotates about the axle as the rack arm is extended or retracted. The cam includes a curved cam groove having an inner end and an outer end, wherein the inner end is located radially closer to the axle than the outer end. The spring assembly includes a spring, a spring arm attached to the spring at a first end and including a follower pin at a second end of the spring arm opposite the first end, the follower pin located in the cam groove such that the spring arm moves when the cam rotates, applying a force to the spring, and a spring arm attachment also attached to the base, the tray or screen assembly, or the parallelogram arm.

The present disclosure relates to a surgical microscope assembly including a parallogram arm, a surgical microscope, an arm head, an arm base, and a movable rack arm assembly attached to the parallelogram arm, the arm head, or the arm base. The movable rack arm assembly includes a cam housing including an internal rack arm guide pin and an axle, a circular gear including circular gear teeth and mounted on and rotatable about the axle, a rack arm, a cam, and a spring assembly. The rack arm includes a rack arm attachment attached to the parallelogram arm, arm head, or arm base, a rack gear including rack gear teeth, and a rack arm track associated with the internal rack arm guide pin to hold the rack gear teeth engaged with the circular gear teeth as the rack arm is extended or retracted with respect to the cam housing such that the circular gear is rotated about the axle as the rack arm is extended or retracted. The cam is attached to the circular gear such that the cam rotates in a corresponding manner when the circular gear rotates about the axle as the rack arm is extended or retracted. The cam includes a curved cam groove having an inner end and an outer end, wherein the inner end is located radially closer to the axle than the outer end. The spring assembly includes a spring, a spring arm attached to the spring at a first end and including a follower pin at a second end of the spring arm opposite the first end, the follower pin located in the cam groove such that the spring arm moves when the cam rotates, applying a force to the spring, and a spring arm attachment attached to the parallelogram arm, the arm head, or the arm base.

The present disclosure relates to a customizable force profile spring assembly including a first member, a second member, a cam, and a spring. The first member is restrained, so that it can only move along a single axis. The second member is also restrained so that it can only move along a single axis. The first member is mechanically coupled to the cam, such as with a gear, so that as it travels along its axis of travel, it causes the cam to rotate. The cam, in turn, is mechanically coupled to the second member, and the rotation of the cam causes the second member to move along its axis of travel. The movement of the second member exerts force on a spring, causing the spring to deflect.

The present disclosure relates to a movable rack arm assembly including a cam housing including an internal rack arm guide pin and an axle, a circular gear including circular gear teeth and mounted on and rotatable about the axle, a rack arm, a cam, and a spring assembly. The rack arm includes a rack gear including rack gear teeth and a rack arm track associated with the internal rack arm guide pin to hold the rack gear teeth engaged with the circular gear teeth as the rack arm is extended or retracted with respect to the cam housing such that the circular gear is rotated about the axle as the rack arm is extended or retracted. The cam is attached to the circular gear such that the cam rotates in a corresponding manner when the circular gear rotates about the axle as the rack arm is extended or retracted. The cam includes a curved cam groove having an inner end and an outer end, wherein the inner end is located radially closer to the axle than the outer end. The spring assembly includes a spring and a spring arm attached to the spring at a first end and including a follower pin at a second end of the spring arm opposite the first end, the follower pin located in the cam groove such that the spring arm moves when the cam rotates, applying a force to the spring.

The above surgical console, surgical microscope assembly, customizable force profile spring assembly, or movable rack arm may each have one or more of the following additional features, which may be combined with one another or with other aspects of the present disclosure, unless clearly mutually exclusive:.

A more complete understanding of the present disclosure and its features and advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings, which are not necessarily to scale, in which like reference numbers indicate like features, and wherein:.

The present disclosure provides a movable rack arm assembly including a movable rack arm with a counterbalance spring that allows contoured non-linear force transfer with respect to the movable rack arm. The present disclosure also provides equipment, such as surgical equipment, particularly ophthalmic surgical equipment containing such a movable rack arm assembly.

<FIG> and <FIG> (referred to collectively as <FIG>) illustrate a movable rack arm assembly <NUM>, which includes cam housing <NUM>, rack arm <NUM>, circular gear <NUM>, cam <NUM>, and spring assembly <NUM>.

Cam housing <NUM> may be any shape sufficient to hold attached internal rack arm guide pin <NUM>, rack arm guide <NUM>, and axle <NUM> in place with respect to one another.

Rack arm <NUM> includes rack gear <NUM> disposed on an external surface of rack arm <NUM>. Rack arm <NUM> also includes rack arm track <NUM>, which is a cavity formed wholly or partially through the interior of rack arm <NUM> and sized to closely fit on internal rack arm guide pin <NUM>, which is attached to cam housing <NUM>. Rack arm track <NUM> may also closely fit on rack arm guide pin <NUM>, which is part of rack arm guide <NUM>. Together internal rack arm guide pin <NUM> and housing wall rack arm guide pin <NUM> help keep the teeth of rack gear <NUM> in engaging contact with the teeth of circular gear <NUM> as rack arm <NUM> extends and retracts. Rack arm guide <NUM> may contain rack arm guide orifice <NUM> through which rack arm <NUM> passes as it extends and retracts. Rack arm guide orifice <NUM> may also help keep rack arm <NUM> in the proper position for the teeth of rack gear <NUM> to be in engaging contact with the teeth of circular gear <NUM> as rack arm <NUM> extends and retracts. Rack arm guide pin <NUM> may be located in rack arm guide orifice <NUM>, as shown, or in another part of rack arm guide <NUM>.

Rack arm <NUM> may also include rack arm attachment orifice <NUM> at an end external to cam housing <NUM> and opposite the end that engages with circular gear <NUM>. Rack arm attachment orifice <NUM> may allow attachment to additional objects, such as further arms or components of medical equipment, such as trays, screens, microscopes, or mounting brackets.

Rack arm <NUM> is shown in <FIG> as a linear rack arm formed as one piece. However, rack arm <NUM> may include curved portions and may be formed as a plurality of pieces.

Circular gear <NUM> is mounted on axle <NUM> so that it may rotate around axle <NUM> in response to movement of rack arm <NUM>, due to engagement of the teeth of rack gear <NUM> with the teeth of circular gear <NUM>.

Circular gear <NUM> may be attached to cam <NUM>, for example by adhesive, melting, screw fasteners, riveting, or welding, or circular gear <NUM> may be integrally formed with cam <NUM>, as is possible in plastic injection molding or metal casting, such that rotational movement of circular gear <NUM> results in corresponding rotational movement of cam <NUM>. Axle <NUM> may be rigidly attached to housing <NUM> and go through pivot holes or radial bearings mounted in cam <NUM> and gear <NUM> or both. Alternately, axle <NUM> may be rigidly attached to cam <NUM> or gear <NUM> or both and go through a pivot hole or bearing mounted in housing <NUM>.

Cam <NUM> includes curved cam groove <NUM>, which may be located on the same or opposite side of cam <NUM> as circular gear <NUM>. Cam groove <NUM> may be formed wholly or partially through the interior of cam <NUM>. Curved cam groove <NUM> is sized to closely fit follower pin <NUM>, so that follower pin <NUM> may move along curved cam groove <NUM>, but will engage the walls of curved cam groove <NUM> with sufficient static friction to remain in place, even when a force is exerted by spring <NUM>, throughout the entire extension or retraction of rack arm <NUM> as permitted by the length of rack arm track <NUM>.

Curved cam groove <NUM> has an inner end <NUM> and an outer end <NUM>. Inner end <NUM> is a shorter radial distance from axle <NUM> than outer end <NUM>. The increase in radial distance from axle <NUM> as a function of curved cam groove <NUM> distance from inner end <NUM> may vary. In addition, although <FIG> shows a curved cam groove <NUM> for which the radial distance from axle <NUM> consistently increases as curved cam groove <NUM> distance from inner end <NUM> increases, other groove configurations are possible, such as those in which radial distance from axle <NUM> increases and decreases as curved cam groove <NUM> distance from inner end <NUM> increases. Such a curved cam groove <NUM> would exhibit a wave shape.

As cam <NUM> rotates in response to a force applied to rack arm <NUM>, follower pin <NUM> moves in cam groove <NUM>. Follower pin <NUM> is part of spring arm <NUM> in spring assembly <NUM>, so spring arm <NUM> also moves. Follower pin <NUM> may include a radial ball bearing (not shown) to allow lower friction contact with the cam groove <NUM>. Movement of spring arm <NUM> is resisted by spring <NUM>, which is attached to spring arm <NUM>, for example by spring attachment hole <NUM>, and to spring cam housing <NUM>, for example by spring attachment pin <NUM>, which is attached to spring cam housing <NUM>.

Spring arm <NUM> is able to move in and out of cam housing <NUM> through spring arm orifice <NUM>. Spring arm may be held in place by spring arm guide <NUM>, through which spring arm <NUM> passes. Spring arm guide <NUM> may be located, at one end, in spring arm orifice <NUM>, or if may be securely held in spring housing <NUM>, or both. Spring housing <NUM> may also be attached to cam housing <NUM> around spring arm orifice <NUM>.

Spring assembly <NUM>, and particularly spring housing <NUM>, may also include spring arm attachment orifice <NUM> at an end external to cam housing <NUM> and opposite follower pin <NUM>. Spring arm attachment orifice <NUM> may allow attachment to additional objects, such as mounting brackets and chassis.

Spring <NUM> as shown is an extension spring, which resists forces that axially lengthen spring <NUM>. Spring <NUM> may also be a compression spring, which resists forces that axially shorten spring <NUM>. Other spring formats may also be used.

In <FIG>, rack arm <NUM> is in a fully extended position. In <FIG>, rack arm <NUM> is in a fully retracted position. It will be understood that, during use of movable rack arm assembly <NUM>, rack arm <NUM> may move between the fully extended position and the fully retracted position, which may also result in movement of circular gear <NUM> and cam <NUM>, such that follower pin <NUM> will be in a different position along curved cam groove <NUM> than is shown in <FIG> or <FIG> and spring <NUM> will be differently extended or compressed.

As illustrated in <FIG>, movable rack arm assembly <NUM> may be part of a surgical console <NUM>. Surgical console <NUM> includes base <NUM> to which mounting attachment <NUM> is attached. Parallelogram arm <NUM> connects mounting attachment <NUM> to tray joint <NUM> and attaches at arm joints <NUM>. Arm joints <NUM> may operate, for example as shown using a screw, bolt, or shaft. Arm joints <NUM> may also operate using other mechanisms, such as flanges, slots, or snap joints. Movable rack arm assembly <NUM> may be mounted to parallelogram arm <NUM> using rack arm <NUM> and/or spring assembly <NUM>. Rack arm <NUM> and/or spring assembly <NUM> may be attached to parallelogram arm <NUM>, for example as shown using a screw, bolt, or shaft placed through rack arm attachment orifice <NUM> and/or spring assembly attachment orifice <NUM>. Rack arm <NUM> and spring assembly <NUM> may be attached directly to base <NUM> or mounting attachment <NUM> in a similar manner. In addition, rack arm <NUM> and spring assembly <NUM> may be attached to parallelogram arm <NUM>, mounting attachment <NUM>, or directly to base <NUM> using other mounting mechanisms, such as flanges and slots or snap joints.

Surgical console <NUM> also includes tray <NUM> which may be attached to parallelogram arm <NUM>, for example at arm joints <NUM>. As illustrated, tray <NUM> is attached to tray arm <NUM> which is attached to tray joint <NUM>. also shows tray joint <NUM> connected to mounting attachment <NUM> by parallelogram arm <NUM>. However, tray arm <NUM>, tray joint <NUM>, or tray <NUM> may be attached directly to rack arm <NUM>, spring assembly <NUM>, and/or parallelogram arm <NUM>.

Although surgical console <NUM> is depicted with tray <NUM>, other objects, such as a screen, may be mounted in a manner similar to and used in place of tray <NUM>.

In addition, although <FIG> depicts attachment of tray <NUM> or similar object to base <NUM> to form surgical console <NUM>, a wall or bed mount may be used in place of base <NUM>.

As illustrated in <FIG>, movable rack arm assembly <NUM> may be part of a surgical microscope system <NUM>. Surgical microscope system <NUM> includes base <NUM> to which arm body <NUM> is attached. Arm body <NUM> may be attached to microscope mount <NUM> via parallelogram arm <NUM> and arm head <NUM>. Arm body <NUM> is the point of attachment for parallelogram arm <NUM>. Arm body <NUM> may be part of base <NUM>. Movable rack arm assembly <NUM> may be mounted to parallelogram arm <NUM>, for example as shown using a screw, bolt, or shaft placed through spring assembly attachment orifice <NUM> and rack arm attachment orifice <NUM>. Spring assembly <NUM> and rack arm <NUM> may also be attached to parallelogram arm <NUM> using other mounting mechanisms, such as flanges and slots or snap joints.

Surgical microscope system <NUM> also includes surgical microscope <NUM>, which may be an ophthalmic surgical microscope. Surgical microscope <NUM> may be attached to microscope mount <NUM>. Surgical microscope <NUM>, arm head <NUM>, or arm body <NUM> may be attached directly to rack arm <NUM> or spring assembly <NUM> through a screw, bolt, or shaft placed through rack arm attachment orifice <NUM> or spring assembly attachment orifice <NUM>. In addition, rack arm <NUM> and spring assembly <NUM> may be attached using other mounting mechanisms, such as flanges, slots, or snap joints.

Although surgical microscope system <NUM> is depicted with surgical microscope <NUM>, other objects, particularly other measurement equipment, such as an OCT scanner, may be mounted in a manner similar to and used in place of surgical microscope <NUM>.

In addition, although <FIG> depicts attachment of arm body <NUM> to base <NUM> a wall or bed mount may be used in place of base <NUM>. Furthermore, parallelogram arm <NUM> might be attached to base <NUM>, or may also be attached to a wall or bed mount.

In use, movement of follower pin <NUM> along curved cam groove <NUM> in response to extension or retraction of rack arm <NUM> causes a non-linear transfer of force, due to compression or extension of spring <NUM>. As a result, a different amount of force is needed to extend to retract rack arm <NUM>, depending on how far it is already extended or retracted.

<FIG> shows a magnified view of <FIG> with the parallelogram arm <NUM> in the middle position.

<FIG> shows a magnified view of <FIG> with the parallelogram arm <NUM> in the end-of-travel up position. Even when the parallelogram arm <NUM> is at end-of-travel, the follower pin <NUM> might not be at the end of the curved cam groove <NUM>. Therefore, the range of operation allowed by the mechanism may be more than the parallelogram arm requires.

<FIG> shows a magnified view of <FIG> with the parallelogram arm <NUM> in the end-of-travel down position. Even when the parallelogram arm <NUM> is at end-of-travel, the follower pin <NUM> might not be at the end of the curved cam groove <NUM>. Therefore, the range of operation allowed by the mechanism may be more than the parallelogram arm requires.

<FIG> is a representative graph generated using a fifth order polynomial illustrating the displacement of rack arm <NUM> as a function of degrees of rotation of cam <NUM>.

<FIG> is a representative graph of the spring force of an extension counterbalance spring <NUM> as a function of displacement of rack arm <NUM>. As illustrated, the spring force does not linearly correspond with rack arm <NUM> displacement because rack arm <NUM> displacement does not result in a linear increase in extension of spring <NUM>. Instead, extension of spring <NUM> is modulated by rotation of cam <NUM> and movement of follower pin <NUM> in curved cam groove <NUM>.

<FIG> is a representative graph showing user input force as a function of displacement of rack arm <NUM> in the same system of <FIG>. As <FIG> makes clear, the amount of force needed to cause further displacement of rack arm <NUM> is not constant. Instead, it increases to a point, then decreases, due to rotation of cam <NUM>.

A movable rack arm assembly <NUM> exhibiting a user force to displacement profile as shown in <FIG> would be useful for a situation in which accidental bumping is a concern. An accidental bump would be unlikely to be enough to cause rack arm <NUM> to move very much. However, rack arm <NUM> could be intentionally moved by exerting sufficient force, then have its position finely tuned using minimal force one rack arm <NUM> extension reached a certain distance.

Other force profiles may be generated as well. For example, if cam <NUM> had a wave-shaped curved inner groove <NUM>, then the user force to displacement profile might exhibit two hills with a valley between them. Such as profile might be useful when an intermediate displacement of rack arm <NUM> is desired and fine adjustments are needed only at those displacement lengths.

Movable rack arm assembly <NUM> may also reduce acceleration of arm movement and jerking movements of the arm.

The force needed to cause movement of rack arm <NUM> may vary depending on the use of movable rack arm assembly <NUM>, but typically a force of between <NUM> and <NUM>, between <NUM> and <NUM>, or between <NUM> and <NUM>, inclusive, may be used for surgical equipment. Typically a force of between <NUM> and <NUM>, inclusive and particularly around <NUM> lbf may be used for surgical trays, such as tray <NUM> and similar objects. Typically a force of between <NUM> and <NUM>, inclusive lbf may be used for surgical microscopes, such as surgical microscope <NUM> and similar objects.

Although the above description uses a single movable arm <NUM> to illustrate the principles of the disclosure, multiple movable rack arm assemblies <NUM>, with the same or different types of springs and the same or different spring constants may be combined to generate more complex user force to displacement profiles.

<FIG> (referred to collectively as <FIG>) illustrate a first embodiment of customizable force profile spring assembly <NUM>, which includes a first member <NUM>, a second member <NUM>, a cam <NUM>, a gear <NUM>, and a housing <NUM>.

The housing <NUM> acts as an anchor to hold first restraint <NUM> and second restraint <NUM> in place relative to the other components of the customizable force profile spring assembly <NUM>.

First restraint <NUM> and second restraint <NUM> are aperture walls which only allow first member <NUM> and second member <NUM> to extend and retract. First restraint <NUM> keeps first member <NUM> engaged with gear <NUM> during extension and retraction. Gear <NUM> is connected to cam <NUM>, so that when first member <NUM> extends or retracts, cam <NUM> turns.

In this embodiment, cam <NUM> is mechanically coupled to second member <NUM> through pin <NUM>. Pin <NUM> slots into curved groove <NUM>, so that when cam <NUM> rotates, pin <NUM> slides along curved groove <NUM>. Because curved groove <NUM> is curved toward the center of gear <NUM>, pin <NUM> pulls second member <NUM> toward the center of gear <NUM> as cam <NUM> rotates.

In <FIG>, second member <NUM> is attached directly to spring <NUM>, such that when second member <NUM> is pulled toward the center of gear <NUM>, spring <NUM> is deflected. Spring <NUM>'s deflection may increase or decrease the force required to extend or retract first member <NUM>.

<FIG> shows first member <NUM> fully extended. In this embodiment, when first member <NUM> is fully extended spring <NUM> is compressed and pin <NUM> is at the outermost end of curved groove <NUM>. However, in other embodiments, extending first member <NUM> might extend spring <NUM>, or pin <NUM> might be at another point in curved groove <NUM>.

<FIG> shows first member <NUM> fully retracted. In this embodiment, when first member <NUM> is fully retracted, spring <NUM> is extended and pin <NUM> is at the innermost end of curved groove <NUM>. However, in other embodiments, retracting first member <NUM> might retract spring <NUM>, or pin <NUM> might be at another point in curved groove <NUM>. In other embodiments, the curved groove <NUM> may have a different curvature, which will generate a different force profile.

<FIG> (referred to collectively as <FIG>) illustrate a second non-claimed embodiment of customizable force profile spring assembly <NUM>, which includes a first member <NUM>, a second member <NUM>, a cam <NUM>, a gear <NUM>, and a housing <NUM>.

In this embodiment, cam <NUM> is mechanically coupled to second member <NUM> through cam follower <NUM>. Cam follower <NUM> is depicted as a needle bearing, but could be a roller bearing or any other type of cam follower. The oblong shape of cam <NUM> causes cam follower <NUM> to push against second member <NUM> as cam <NUM> rotates. Cam <NUM> may be in different shapes, and different shapes will create different force profiles.

<FIG> shows first member <NUM> fully extended. In this embodiment, when first member <NUM> is fully extended spring <NUM> is compressed and cam <NUM> pushes cam follower <NUM> to its furthest extent. However, in other embodiments, extending first member <NUM> might position cam <NUM> in another orientation; for example, such that cam follower <NUM> is at its innermost extent.

<FIG> shows first member <NUM> fully retracted. In this embodiment, when first member <NUM> is fully retracted spring <NUM> is extended and cam follower <NUM> is at its innermost extent. However, in other embodiments, extending first member <NUM> might position cam <NUM> in another orientation; for example, such that cam follower <NUM> is at its outermost extent.

Claim 1:
A customizable force profile spring assembly (<NUM>), customizable to generate different force profiles as required, the assembly comprising:
a first member restrained by a first restraint such that the first member can only move along a first functional axis;
a cam (<NUM>) mechanically coupled to the first member with a gear such that the movement of the first member along the first functional axis causes the cam to rotate;
a second member
restrained by a second restraint such that it can only move along a second functional axis; and
mechanically attached to the cam such that the rotation of the cam causes the second member to move along the second functional axis; and
a spring (<NUM>) mechanically attached to the second member such that the spring is deflected when the second member moves along the second functional axis, applying force to the spring;
wherein
the spring comprising a counterbalance spring, and the customizable force profile spring assembly further comprises a cam housing;
the cam housing (<NUM>) comprises an axle (<NUM>);
the first restraint comprises an internal rack arm guide pin;
the first functional axis comprises extension and retraction;
the gear is a circular gear (<NUM>) comprising teeth and is configured to rotate about the axle;
the first member further comprises:
a rack arm (<NUM>);
rack gear teeth (<NUM>); and
a rack arm track (<NUM>) associated with the internal rack arm guide pin (<NUM>) to hold the rack gear teeth (<NUM>) engaged with the circular gear teeth as the rack arm (<NUM>) is extended or retracted with respect to the cam (<NUM>);
the cam (<NUM>) is attached to the circular gear and further comprises a curved cam groove (<NUM>) having an inner end and an outer end, wherein the inner end is located radially closer to the axle than the outer end; and
the second member further comprises:
a spring arm (<NUM>) comprising:
a first end mechanically attached to the spring (<NUM>);
a second end opposite the first end; and
wherein the spring arm (<NUM>) is mechanically attached to the cam (<NUM>) with a follower pin (<NUM>) at the second end located in the cam groove (<NUM>).