Patent Description:
Surgical tables, or operating tables, comprising a base for standing on a floor, a column extending from the base, and a tabletop providing a patient support surface are well known.

In order for surgical tables to be versatile, it is necessary for the tabletop to be disposable in a variety of different configurations. <CIT> discloses a surgical table with mechanisms for inclining a tabletop of the table relative to a column of the table and relative to the horizontal about both transverse and longitudinal axes of the tabletop, and a drive assembly for permitting a traverse movement of the tabletop relative to the column in back and forth longitudinal directions of the tabletop. Additional examples of surgical tables capable of orienting in different configurations are disclosed in <CIT>, <CIT>, <CIT>, <CIT> and<CIT>.

There is a need for a surgical table with a mechanism for inclining a tabletop of the table over a greater range of angles about two orthogonal axes, in order to increase the versatility of the table.

Inclination of a tabletop of a surgical table is usually effected by operating one or more actuators connected between the tabletop and a column of the surgical table. The actuator(s) need to be robust to withstand loads to which they are subjected when a patient is present on the tabletop.

There is a need for a surgical table with a mechanism for inclining a tabletop of the table relative to a column of the table that requires less robust actuators.

Some known surgical tables allow for a height of a tabletop thereof relative to a base thereof to be adjusted.

There is a need for a surgical table with an alternative mechanism for adjusting a height of a tabletop thereof.

Surgical tables may have a tabletop and a base that are movable relative to each other between first and second relative positions via a predetermined relative position, such as a predetermined default or home position. Such a predetermined relative position may be, for example, the position at which a patient is most easily transferrable onto or from the table, or the position at which the tabletop and the base are best placed to enable a certain procedure to be performed on a patient supported by the table.

There is a need for a surgical table having an assistance mechanism for helping medical staff using the surgical table to dispose a tabletop and a base of the surgical table at such a predetermined relative position.

Surgical tables often have first and second parts that are movable relative to each other by operating one or more electric actuators connected between the first and second parts.

There is a need for a surgical table having a system for monitoring the state of one or more electric actuators of the table.

There also is a need for a surgical table having a system for monitoring relative movements of first and second parts of the table, such as for future determination of relative movements of the first and second parts that have taken place.

A first aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; a mechanism coupling the tabletop to the column and for enabling rotational movement of the tabletop relative to the column about two orthogonal axes, wherein one of the two orthogonal axes is parallel to the longitudinal direction of the tabletop and the other of the two orthogonal axes is parallel to the transverse direction of the tabletop, the mechanism comprising a first frame connected to the tabletop and a second frame connected to the column and rotatably mounted on the first frame about an axis that is orthogonal to both longitudinal and transverse directions of the tabletop, and first and second actuators, each actuator being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes, wherein the first frame is connected to the column via the first actuator, and the second frame is connected to the column via the second actuator.

In a preferred embodiment of the surgical table, the first frame is connected to the first actuator by a first gimbal mechanism and the second frame is connected to the second actuator by a second gimbal mechanism.

Preferably, the first gimbal mechanism is configured to rotate the tabletop about an axis parallel to the transverse direction of the tabletop (i.e. in a Trendelenburg or reverse Trendelenburg movement) and the second gimbal mechanism is configured to rotate the tabletop about an axis parallel to the longitudinal direction of the tabletop (i.e. in a tilt movement in either a left or right direction relative to the longitudinal direction of the tabletop).

Optionally, each of the first and second actuators is for moving both of the frames about a respective one of the two orthogonal axes.

Optionally, the first frame is connected to the column via the first actuator and via a third actuator in parallel to the first actuator.

Optionally, the total number of actuators via which the first frame is connected to the column is only two.

Optionally, the first and third actuators are connected to opposed sides of the column.

Optionally, each of the first and third actuators is connected to a respective one of two opposite end portions of the first frame.

Optionally, the total number of actuators via which the second frame is connected to the column is only one.

Optionally, one or each of the first and second actuators is connected to the respective frame via a universal joint.

Optionally, the third actuator is connected to the first frame via a universal joint.

Optionally, one or each of the first and second actuators is rotatably connected to the column about only a single axis.

Optionally, the first actuator is rotatably connected to the column about a first axis and the second actuator is rotatably connected to the column about a second axis, wherein the second axis is orthogonal to the first axis.

Optionally, one of the first and second axes is parallel to the longitudinal direction of the tabletop and the other of the first and second axes is parallel to the transverse direction of the tabletop.

Optionally, one or each of the first and third actuators is rotatably connected to the column about only a single axis.

Optionally, the first actuator is rotatably connected to the column about a first axis and the third actuator is rotatably connected to the column about a third axis, wherein the third axis is spaced from and parallel to the first axis.

Optionally, each of the first and second actuators comprises a cylinder connected to one of the column and the respective frame, and an elongate part movably disposed within the cylinder and connected to the other of the column and the respective frame.

Optionally, the third actuator comprises a cylinder connected to one of the column and the first frame, and an elongate part movably disposed within the cylinder and connected to the other of the column and the first frame.

Optionally, each of the first, second and third actuators is extendible, and extension of all of the first, second and third actuators increases the height of the mechanism thereby increasing a height of the tabletop above the column.

Optionally, the surgical table comprises first and second extensible stabilisers, wherein the first frame is connected to the column via the first extensible stabiliser in parallel with the first actuator, and the second frame is connected to the column via the second extensible stabiliser in parallel with the second actuator. Further optionally, the first and second actuators are connected to the respective first and second frames via respective first and second universal joints, and wherein the first and second extensible stabilisers are connected to the respective first and second frames via the respective first and second universal joints.

Optionally, the total number of extensible stabilisers via which the first frame is connected to the column is only two, and the total number of extensible stabilisers via which the second frame is connected to the column is only two.

A second aspect of the present invention as claimed provides a surgical table comprising: a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; and a mechanism coupling the tabletop to the column and for enabling rotational movement of the tabletop relative to the column about two orthogonal axes, the mechanism comprising a first frame connected to the tabletop, a second frame rotatably mounted on the first frame, first and second extensible stabilisers, and first and second actuators disposed outside of both the first and second extensible stabilisers, each actuator being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes; wherein the first frame is connected to the column via the first extensible stabiliser and the first actuator in parallel, and the second frame is connected to the column by the second extensible stabiliser and the second actuator in parallel.

Optionally, the second frame is rotatably mounted on the first frame about an axis that is orthogonal to both longitudinal and transverse directions of the tabletop.

Optionally, one of the two orthogonal axes is parallel to a longitudinal direction of the tabletop and the other of the two orthogonal axes is parallel to a transverse direction of the tabletop.

Optionally, one or each of the first and second extensible stabilisers comprises a cylinder connected to one of the column and the respective frame, and an elongate part movably disposed within the cylinder and connected to the other of the column and the respective frame.

Optionally, one of the first and second axes is parallel to a longitudinal direction of the tabletop and the other of the first and second axes is parallel to a transverse direction of the tabletop.

Optionally, one or each of the first and second extensible stabilisers is rotatably connected to the column about only a single axis.

Optionally, the first extensible stabiliser is rotatably connected to the column about the first axis or an axis parallel to the first axis, and the second extensible stabiliser is rotatably connected to the column about the second axis or an axis parallel to the second axis.

Optionally, the first actuator is connected to the first frame via a first universal joint. Further optionally, the first extensible stabiliser is connected to the first frame via the first universal joint.

Optionally, the second actuator is connected to the second frame via a second universal joint. Further optionally, the second extensible stabiliser is connected to the second frame via the second universal joint.

Optionally, in the surgical table of the first aspect or of the second aspect, the column is of adjustable height.

Optionally, in the surgical table of the first aspect or of the second aspect, the first frame is connected to the tabletop via a tabletop traverse mechanism for enabling movement of the tabletop relative to the column in a selected longitudinal direction of the tabletop.

A third aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor, a column extending from the base and having a height that is adjustable between a minimum height and a maximum height, a tabletop providing a patient support surface, a mechanism of adjustable height coupling the tabletop to the column, a mechanism height adjustment system for adjusting the height of the mechanism, and a controller configured to control the mechanism height adjustment system to adjust the height of the mechanism only when the height of the column is one of the minimum height and the maximum height.

Optionally, the surgical table comprises a column height adjustment system for adjusting the height of the column between the minimum height and the maximum height, wherein the controller is configured to control the column height adjustment system.

A fourth aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor, a column extending from the base and having a height that is adjustable between a first minimum height and a first maximum height, a tabletop providing a patient support surface, a mechanism coupling the tabletop to the column and having a height that is adjustable between a second minimum height and a second maximum height, a column height adjustment system for adjusting the height of the column between the first minimum height and the first maximum height, a mechanism height adjustment system for adjusting the height of the mechanism between the second minimum height and the second maximum height, and a controller configured to control the column height adjustment system to adjust the height of the column and then to control the mechanism height adjustment system to adjust the height of the mechanism, in order to adjust a height of the tabletop above the base.

Optionally, the controller is configured to adjust the height of the column to one of the first minimum height and the first maximum height and then to control the mechanism height adjustment system to adjust the height of the mechanism, in order to adjust a height of the tabletop above the base. Further optionally, the controller is configured to control the mechanism height adjustment system to adjust the height of the mechanism, then to control the column height adjustment system to adjust the height of the column to one of the first minimum height and the first maximum height, and then to control the mechanism height adjustment system to further adjust the height of the mechanism, in order to adjust a height of the tabletop above the base. Still further optionally, the controller is configured to control the mechanism height adjustment system to adjust the height of the mechanism to a height between the second minimum height and the second maximum height, then to control the column height adjustment system to adjust the height of the column to one of the first minimum height and the first maximum height, and then to control the mechanism height adjustment system to adjust the height of the mechanism to one of the second minimum height and the second maximum height, in order to adjust a height of the tabletop above the base.

Optionally, in the surgical table of the third aspect or of the fourth aspect, the column comprises a first part connected to one of the base and the mechanism, and a second part movably disposed within the first part and connected to the other of the base and the mechanism.

Optionally, in the surgical table of the third aspect or of the fourth aspect, the column height adjustment system is for causing relative movement of the first and second parts.

Optionally, in the surgical table of the third aspect or of the fourth aspect, the mechanism is for enabling rotational movement of the tabletop relative to the column about two orthogonal axes. Further optionally, one of the two orthogonal axes is parallel to a longitudinal direction of the tabletop and the other of the two orthogonal axes is parallel to a transverse direction of the tabletop.

Optionally, in the surgical table of the third aspect or of the fourth aspect, the mechanism comprises a first frame connected to the tabletop and a second frame connected to the column and rotatably mounted on the first frame about an axis that is orthogonal to both longitudinal and transverse directions of the tabletop. Further optionally, the surgical table of the third aspect or of the fourth aspect comprises first and second actuators, each actuator being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes, wherein the first frame is connected to the column via the first actuator, and the second frame is connected to the column via the second actuator. Still further optionally, the first frame is connected to the column via the first actuator and via a third actuator in parallel to the first actuator. Yet further optionally, each of the first, second and third actuators is extendible, and extension of all of the first, second and third actuators increases the height of the mechanism thereby increasing a height of the tabletop above the column.

A fifth aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor; a column extending from the base; a tabletop coupled to the column and providing a patient support surface; a tabletop drive mechanism for causing relative translational movement of the tabletop and the base; and a controller for controlling operation of the tabletop drive mechanism; wherein the controller is configured to control the tabletop drive mechanism to cause relative translational movement of the tabletop and the base between first and second relative positions via a predetermined relative position, and configured to control the tabletop drive mechanism to cause the relative translational movement of the tabletop and the base to be paused for a predetermined period of time when the tabletop and the base are at the predetermined relative position.

Optionally, the tabletop drive mechanism is for adjusting a height of the column, and the movement comprises translational movement of the tabletop towards or away from the base.

Optionally, the movement comprises translational movement of the tabletop in a longitudinal direction of the tabletop relative to the base.

Optionally, the surgical table comprises a sensor for sensing, and for notifying the controller of, a relative position of the tabletop and the base. Further optionally, the sensor is for sensing, and for notifying the controller of, when the tabletop and the base are at the predetermined relative position.

Optionally, the predetermined period of time is between <NUM> and <NUM> seconds. Further optionally, the predetermined period of time is between <NUM> and <NUM> seconds. Further optionally, the predetermined period of time is between <NUM> and <NUM> seconds.

A sixth aspect of the present disclosure provides a method of operating a surgical table comprising a base for standing on a floor, a column extending from the base, a tabletop coupled to the column and providing a patient support surface, a tabletop drive mechanism for causing relative translational movement of the tabletop and the base, and a controller for controlling operation of the tabletop drive mechanism, the method comprising: the controller controlling the tabletop drive mechanism to cause relative translational movement of the tabletop and the base between first and second relative positions via a predetermined relative position; and the controller controlling the tabletop drive mechanism to cause the relative translational movement of the tabletop and the base to be paused for a predetermined period of time when the tabletop and the base are at the predetermined relative position.

Optionally, the method comprises sensing a relative position of the tabletop and the base. Further optionally, the method comprises sensing when the tabletop and the base are at the predetermined relative position.

A seventh aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor, a column extending from the base and having a height that is adjustable between a first minimum height and a first maximum height, a difference between the first minimum height and the first maximum height being a first range, a tabletop providing a patient support surface, and a mechanism coupling the tabletop to the column and having a height that is adjustable between a second minimum height and a second maximum height, a difference between the second minimum height and the second maximum height being a second range, wherein the first range is greater than the second range.

Optionally, a ratio of the first range to the second range is between <NUM>:<NUM> and <NUM>:<NUM>. Further optionally, the ratio of the first range to the second range is between <NUM>: <NUM> and <NUM>: <NUM>.

Optionally, the first range is between <NUM> and <NUM> millimeters and the second range is between <NUM> and <NUM> millimeters.

Optionally, the column comprises a first part connected to one of the base and the mechanism, and a second part movably disposed within the first part and connected to the other of the base and the mechanism.

Optionally, the mechanism is for enabling rotational movement of the tabletop relative to the column about two orthogonal axes. Further optionally, one of the two orthogonal axes is parallel to a longitudinal direction of the tabletop and the other of the two orthogonal axes is parallel to a transverse direction of the tabletop.

Optionally, the mechanism comprises a first frame connected to the tabletop and a second frame connected to the column and rotatably mounted on the first frame about an axis that is orthogonal to both longitudinal and transverse directions of the tabletop. Further optionally, the surgical table comprises first and second actuators, each actuator being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes, wherein the first frame is connected to the column via the first actuator, and the second frame is connected to the column via the second actuator. Still further optionally, the first frame is connected to the column via the first actuator and via a third actuator in parallel to the first actuator. Yet further optionally, each of the first, second and third actuators is extendible, and extension of all of the first, second and third actuators increases the height of the mechanism thereby increasing a height of the tabletop above the column.

An eighth aspect of the present disclosure provides a surgical table comprising: first and second relatively movable parts, a drive mechanism comprising an electric actuator for causing relative movement of the first and second parts, a power supply for the electric actuator, a current determiner for determining a current drawn from the power supply by the electric actuator, a memory, and a recorder communicatively connected to the current determiner and the memory and configured to record in the memory an indication of the determined current in dependence on an output of the current determiner.

Optionally, the current determiner is for determining a current drawn from the power supply by the electric actuator while the electric actuator causes relative movement of the first and second parts.

Optionally, the current determiner is for determining respective currents drawn from the power supply by the electric actuator at respective different times, and the recorder is configured to record in the memory respective indications of the determined respective currents.

Optionally, the surgical table comprises a calculator configured to calculate a cumulative current drawn from the power supply by the electric actuator over a period of time.

Optionally, the surgical table comprises an overload determiner for determining when the electric actuator is overloaded in dependence on an output of one of the current determiner and the recorder or in dependence on a content of the memory. Further optionally, the surgical table comprises an indicator for indicating to a user when the electric actuator is overloaded in dependence on an output of the overload determiner.

Optionally, the surgical table comprises a base for standing on a floor, a column extending from the base, and a tabletop coupled to the column and providing a patient support surface, wherein the first part comprises the tabletop and the second part comprises one of the column and the base.

A ninth aspect of the present disclosure provides a method of operating a surgical table comprising first and second relatively movable parts, a drive mechanism comprising an electric actuator for causing relative movement of the first and second parts, a power supply for the electric actuator, a current determiner for determining a current drawn from the power supply by the electric actuator, a memory, and a recorder communicatively connected to the current determiner and the memory and configured to record in the memory an indication of the determined current in dependence on an output of the current determiner; the method comprising: the current determiner determining a current drawn from the power supply by the electric actuator; and the recorder recording in the memory an indication of the determined current in dependence on an output of the current determiner.

Optionally, the method comprises the current determiner determining a current drawn from the power supply by the electric actuator while the electric actuator causes relative movement of the first and second parts.

Optionally, the method comprises the current determiner determining respective currents drawn from the power supply by the electric actuator at respective different times, and the recorder recording in the memory respective indications of the determined respective currents.

Optionally, the surgical table comprises a calculator, and the method comprises the calculator calculating a cumulative current drawn from the power supply by the electric actuator over a period of time.

Optionally, the surgical table comprises an overload determiner, and the method comprises the overload determiner determining when the electric actuator is overloaded in dependence on an output of one of the current determiner and the recorder or in dependence on a content of the memory. Further optionally, the surgical table comprises an indicator, and the method comprises the indicator indicating to a user when the electric actuator is overloaded in dependence on an output of the overload determiner.

Optionally, the surgical table comprises a base for standing on a floor, a column extending from the base, and a tabletop coupled to the column and providing a patient support surface, and wherein the first part comprises the tabletop and the second part comprises one of the column and the base.

A tenth aspect of the present disclosure provides a surgical table comprising: first and second relatively movable parts, a drive mechanism for causing relative movement of the first and second parts, a non-contact movement determiner for determining a relative movement of the first and second parts, a memory, and a recorder communicatively connected to the movement determiner and the memory and configured to record in the memory an indication of the detected relative movement in dependence on an output of the movement determiner.

Optionally, the surgical table comprises a controller for controlling the drive mechanism, wherein the movement determiner is communicatively connected to the controller and is configured to determine a relative movement of the first and second parts on the basis of an output of the controller.

Optionally, the surgical table comprises a sensor for sensing a relative position of the first and second parts, wherein the movement determiner is communicatively connected to the sensor and is configured to determine a relative movement of the first and second parts on the basis of an output of the sensor.

Optionally, the movement determiner is for determining respective relative movements of the first and second parts at respective different times, and the recorder is configured to record in the memory respective indications of the determined respective relative movements.

Optionally, the surgical table comprises third and fourth relatively movable parts, a drive mechanism for causing second relative movement of the third and fourth parts, wherein the movement determiner is for determining a second relative movement of the third and fourth parts, and wherein the recorder is configured to record in the memory an indication of the detected second relative movement in dependence on an output of the movement determiner. Further optionally, the surgical table comprises an indicator for indicating to a user, in dependence on a content of the memory, (a) a sequence of past relative movements of the first and second parts and/or of the third and fourth parts, and/or (b) a last-performed relative movement of the first and second parts and/or of the third and fourth parts.

Optionally, the surgical table comprises a base for standing on a floor, a column extending from the base, and a tabletop coupled to the column and providing a patient support surface, wherein the first part comprises one of the tabletop and a part of the column and the second part comprises one of the column and the base.

An eleventh aspect of the present disclosure provides a method of operating a surgical table comprising first and second relatively movable parts, a drive mechanism for causing relative movement of the first and second parts, a non-contact movement determiner for determining a relative movement of the first and second parts, a memory, and a recorder communicatively connected to the movement determiner and the memory and configured to record in the memory an indication of the detected relative movement in dependence on an output of the movement determiner; the method comprising: the movement determiner determining a relative movement of the first and second parts; and the recorder recording in the memory an indication of the detected relative movement in dependence on an output of the movement determiner.

Optionally, the surgical table comprises a controller for controlling the drive mechanism, wherein the movement determiner is communicatively connected to the controller, and the method comprises the movement determiner determining a relative movement of the first and second parts on the basis of an output of the controller.

Optionally, the surgical table comprises a sensor for sensing a relative position of the first and second parts, wherein the movement determiner is communicatively connected to the sensor, and the method comprises the movement determiner determining a relative movement of the first and second parts on the basis of an output of the sensor.

Optionally, the method comprises the movement determiner determining respective relative movements of the first and second parts at respective different times, and the recorder recording in the memory respective indications of the determined respective relative movements.

Optionally, the surgical table comprises third and fourth relatively movable parts, a drive mechanism for causing second relative movement of the third and fourth parts, and the method comprises the movement determiner determining a second relative movement of the third and fourth parts, and the recorder recording in the memory an indication of the detected second relative movement in dependence on an output of the movement determiner.

Optionally, the surgical table comprises an indicator, and the method comprises the indicator indicating to a user, in dependence on a content of the memory, (a) a sequence of past relative movements of the first and second parts and/or of the third and fourth parts, and/or (b) a last-performed relative movement of the first and second parts and/or of the third and fourth parts.

A twelfth aspect of the present disclosure provides a surgical table comprising: first and second relatively movable parts; a mechanism coupling the first part to the second part, the mechanism comprising an extensible stabiliser and an actuator disposed outside of the extensible stabiliser, wherein the first part is connected to the second part via the extensible stabiliser and the actuator in parallel; a sensor comprised in the extensible stabiliser; and a controller configured to control the actuator to adjust a length of the actuator on the basis of an output of the sensor.

Optionally, the table comprises a base for standing on a floor; a column extending from the base; and a tabletop providing a patient support surface, wherein the first part is the tabletop and the second part is the column.

Optionally, the extensible stabiliser comprises a magnet, and the sensor comprises one of a hall effect sensor and a reed switch configured to detect a magnetic field of the magnet. Further optionally, the extensible stabiliser comprises a cylinder and an elongate part movably disposed within the cylinder, wherein the sensor is comprised in one of the cylinder and the elongate part, and the magnet is comprised in the other of the cylinder and the elongate part.

A thirteenth aspect of the present disclosure provides a surgical table comprising: a base for standing on a floor; a column extending from the base; a tabletop providing a patient support surface; and a mechanism coupling the tabletop to the column and for enabling rotational movement of the tabletop relative to the column about two orthogonal axes, the mechanism comprising a first frame connected to the tabletop, a second frame rotatably mounted on the first frame, an extensible stabiliser, and first, second and third actuators disposed outside of the extensible stabiliser, each of the first and second actuators being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes; wherein the first frame is connected to the column via the first and third actuators in parallel, and the second frame is connected to the column by the extensible stabiliser and second actuator in parallel; and wherein the total number of actuators via which the first frame is connected to the column is only two, and the total number of actuators via which the second frame is connected to the column is only one.

Optionally, the third actuator is rotatably connected to the column about an axis parallel to the first axis.

Optionally, the extensible stabiliser is rotatably connected to the column about an axis parallel to the second axis.

As described above, in a preferred embodiment of the surgical table, the first frame is connected to the first actuator by a first gimbal mechanism and the second frame is connected to the second actuator by a second gimbal mechanism. Preferably, the first gimbal mechanism is configured to rotate the tabletop about an axis parallel to the transverse direction of the tabletop (i.e. in a Trendelenburg or reverse Trendelenburg movement) and the second gimbal mechanism is configured to rotate the tabletop about an axis parallel to the longitudinal direction of the tabletop (i.e. in a tilt movement in either a left or right direction relative to the longitudinal direction of the tabletop).

The provision of such a rotatable mounting between the first and second frames which have respective gimbal mechanisms to cause trend and tilt movement, respectively and independently, of the tabletop provides high angles of trend and tilt movement about the respective axes.

Also, this rotatable mounting can avoid the provision of any sliding joint between the trend and tilt actuators and the tabletop.

In addition, the trend and tilt actuators can provide a secondary height extension for the tabletop relative to the column, i.e. raise and lower the tabletop relative to the column.

Furthermore, in the preferred embodiment, there are two trend actuators rotatably connected to respective opposite sides of the first frame for independently rotating the first frame about the trend axis and the combination of a single tilt actuator and an extensible stabiliser rotatably connected to respective opposite sides of the second frame for independently rotating the second frame about the tilt axis. The actuators are driven and are active, whereas the extensible stabiliser is undriven and is passive.

The driven actuators typically have very limited slack, whereas the extensible stabiliser has a high degree of slack as it is undriven.

By providing two opposite actuators for rotating the tabletop about the trend axis, high trend loads can be carried by the opposite trend actuators. The tilt load of a tabletop is generally lower than the trend load, and consequently a single tilt actuator can be employed, in combination with an opposite passive extensible stabiliser. This lowers the cost and complexity of the tilt and trend mechanism.

Moreover, by providing only three actuators, two for trend and one for tilt, this minimises the possibility of the tilt and trend mechanism being subjected to excessive loads and/or locking up. Actuators used in surgical tables, such as leadscrews and ballscrews, tend to have a small tolerance of movement and typically exhibit some small positioning error. If there were two pairs of driven actuators, two for trend and two for tilt, there is a likelihood that the positioning errors may cumulatively cause excessive stress on the actuators, and wear, failure or locking up of the tilt and trend mechanism, since the cumulative positioning errors could not be accommodated in a drive system with little freedom of movement.

In contrast, in the preferred embodiment of the surgical table of the present invention there is one pair of driven actuators for trend, and the combination of a driven actuator and a passive extensible stabiliser for tilt. The passive extensible stabiliser, which has a high freedom of movement, can accommodate any cumulative positioning errors, thereby reducing excessive stress on the actuators, and minimising the risk of wear, failure or locking up of the tilt and trend mechanism.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:-.

Referring to <FIG>, a surgical table, designated generally as <NUM>, includes a base <NUM>, which stands on a floor <NUM>, a column <NUM> of adjustable height extending from the base <NUM> and a tabletop <NUM> providing a patient support surface <NUM>. In a variation to this embodiment, the column <NUM> is not of adjustable height. The base <NUM> may include wheels for moving the table <NUM> along the floor <NUM>.

As depicted in <FIG>, the tabletop <NUM> is divided into five sections, namely a head section <NUM>, an upper torso section <NUM>, a lower torso section <NUM> and a pair of laterally adjacent leg sections <NUM>, <NUM>, of which only one is shown in <FIG>. Each of the sections of the tabletop <NUM> provides a portion of the patient support surface <NUM>, and each of the sections has a respective separate mattress <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

The lower torso section <NUM> is coupled to the column <NUM>. A lower end <NUM> of the upper torso section <NUM> is detachably mounted on an upper end <NUM> of the lower torso section <NUM> by means of transversely adjacent first and second pivot joints <NUM>, <NUM>, which define a transverse axis about which the upper torso section <NUM> can be displaced relative to the lower torso section <NUM>.

Each of the leg sections <NUM> is detachably mounted on a lower end <NUM> of the lower torso section <NUM> by a respective one of transversely adjacent third and fourth pivot joints <NUM>, <NUM>, of which only one is visible in <FIG>, for displacement relative to the lower torso section <NUM> about a transverse axis defined by the respective one of third and fourth pivot joints <NUM>, <NUM>.

A lower end <NUM> of the head section <NUM> is detachably mounted on an upper end <NUM> of the upper torso section <NUM> by means of a fifth pivot joint <NUM> defining a transverse axis about which the head section <NUM> can be displaced relative to the upper torso section <NUM>. The angle of inclination of the head section <NUM> is controlled manually by means of a pair of conventional adjustable struts <NUM>, only one of which is shown in <FIG>, secured to and extending between the underside of the head section <NUM> and the upper torso section <NUM>, one on each side of the tabletop <NUM>. The struts <NUM> may be hydraulic or electric actuators or lockable gas springs.

The provision of the five pivot joints <NUM>, <NUM>, <NUM>, <NUM>, <NUM> permits the five sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM> selectively to be inclined relative to adjacent sections <NUM>, <NUM>, <NUM>, <NUM>, <NUM> thereby to dispose the tabletop <NUM> in a selected configuration. Moreover, that the head section <NUM> is detachable from the upper torso section <NUM>, and each of the upper torso section <NUM> and the leg sections <NUM>, <NUM> is detachable from the lower torso section <NUM> means that the table <NUM> may be made compact for storage.

As described in more detail below, the surgical table <NUM> also includes mechanisms for inclining the whole tabletop <NUM> relative to the column <NUM> and base <NUM> and relative to the horizontal about transverse and longitudinal axes of the tabletop <NUM>. Inclination about the transverse axis of the tabletop <NUM> is referred to in the art as "trending", which is a shortening of the term "Trendelenburg", while inclination about the longitudinal axis of the tabletop <NUM> is referred to as "tilting". The trend and tilt movements can be controlled independently. Compound movements also are possible, in which the tabletop <NUM> is inclined about both the transverse and longitudinal axes of the tabletop <NUM> at the same time.

As used herein, the longitudinal axis of the tabletop is the major axis of the tabletop and the transverse axis of the tabletop is the orthogonal minor axis of the tabletop. The longitudinal direction of the tabletop is parallel to the major axis and the transverse direction of the tabletop is parallel to the minor axis. That is, the transverse direction of the tabletop is perpendicular to, or orthogonal to, the longitudinal direction of tabletop.

The surgical table <NUM> includes a mechanism for selectively increasing or decreasing the height of the column <NUM> (i.e. increasing or decreasing the distance between the base <NUM> and the tabletop <NUM>), thereby to adjust the height of the tabletop <NUM> above the base <NUM> and floor <NUM>.

<FIG> show first, second and third parts <NUM>, <NUM>, <NUM> of the column <NUM>, which are in the form of first, second and third nestable tubes that have respective longitudinal axes that are coincident with a vertical axis V-V of the table <NUM>. The first, second and third parts <NUM>, <NUM>, <NUM> of the column <NUM> are disposed within the outer telescopic casing <NUM> of the column <NUM> shown in <FIG>. The third tube <NUM> has a substantially square outer cross section and, although not shown in these Figures, has a bottom end that is fixed to the base <NUM>. Accordingly, the column <NUM> extends upwardly from the base <NUM> in the direction of the vertical axis V-V of the table <NUM>. The second tube <NUM> has substantially square inner and outer cross sections, the inner cross section of the second tube <NUM> being of slightly greater dimensions than the outer cross section of the third tube <NUM>, to enable the third tube <NUM> to be slidably disposed within the second tube <NUM>. Each of the second and third tubes <NUM>, <NUM> has a guide that cooperates with a guide of the other of the second and third tubes <NUM>, <NUM>, to guide movement of the second tube <NUM> relative to the third tube <NUM> in the direction of the vertical axis V-V of the table <NUM>. The first tube <NUM> has substantially square inner and outer cross sections, the inner cross section of the first tube <NUM> being of slightly greater dimensions than the outer cross section of the second tube <NUM>, to enable the second tube <NUM> to be slidably disposed within the first tube <NUM>. Each of the first and second tubes <NUM>, <NUM> has a guide that cooperates with a guide of the other of the first and second tubes <NUM>, <NUM>, to guide movement of the first tube <NUM> relative to the second tube <NUM> in the direction of the vertical axis V-V of the table <NUM>.

Within the third tube <NUM> is disposed a column height adjustment system <NUM> comprising an extendible column actuator <NUM> (see <FIG>), such as an electric linear (e.g. screw) actuator. One part of the column actuator is fixed to the base <NUM> or the third tube <NUM>, and another part of the column actuator is fixed to an upper part of the first tube <NUM>. The two parts of the column actuator move relative to each other when the column actuator is extended. Accordingly, when the column actuator is operated so as to be extended, the first tube <NUM> is raised relative to the second and third tubes <NUM>, <NUM> and relative to the base <NUM>, thereby to increase the height of the column <NUM> and thereby to increase the height of the tabletop <NUM> above the base <NUM>. As a lower end of the first tube <NUM> reaches an upper end of the second tube <NUM>, cooperating features of the first and second tubes <NUM>, <NUM> cause the second tube <NUM> to be lifted with the first tube <NUM> relative to the third tube <NUM> and relative to the base <NUM>, thereby to further increase the height of the column <NUM> and thereby to further increase the height of the tabletop <NUM> above the base <NUM>. As a lower end of the second tube <NUM> reaches an upper end of the third tube <NUM>, cooperating features of the second and third tubes <NUM>, <NUM> prevent further lifting of the first and second tubes <NUM>, <NUM> by the column actuator and the column <NUM> has reached its maximum height.

In <FIG>, the column <NUM> is shown at its minimum height, with the first, second and third tubes <NUM>, <NUM>, <NUM> nested together to the maximum possible extent. When the first tube <NUM> has been elevated to its maximum possible height relative to the base <NUM>, the first, second and third tubes <NUM>, <NUM>, <NUM> are un-nested to the maximum possible extent, whereby the column <NUM> is then at its maximum height. Of course, in variations to this embodiment, the column <NUM> may have only two parts <NUM>, <NUM> or more than three parts <NUM>, <NUM>, <NUM>.

In accordance with one aspect of the present invention, a surgical table is provided with a mechanism for inclining a tabletop of the table over a wide range of angles about two orthogonal axes. In the present embodiment, the surgical table <NUM> is provided with a mechanism to enable the whole tabletop <NUM> to be inclined relative to the horizontal about a transverse axis across the table <NUM> and the whole tabletop <NUM> to be inclined relative to the horizontal about a longitudinal axis extending along the length of the tabletop <NUM>. More particularly, the upper torso section <NUM> of the tabletop <NUM> is coupled to the column <NUM> by a mechanism <NUM> that is adapted to be movable, by operation of a drive mechanism, to enable the upper torso portion <NUM> and the rest of the tabletop <NUM> to be rotatably moved relative to the column <NUM> and relative to the horizontal about either or both of two orthogonal axes.

The mechanism <NUM> comprises a first frame or plate <NUM> which is connected to an underside of the upper torso section <NUM> of the tabletop <NUM> via a tabletop traverse mechanism (not shown) for enabling movement of the tabletop <NUM> relative to the column <NUM> and base <NUM> in a selected longitudinal direction of the tabletop <NUM>. In a variation to this embodiment, the tabletop traverse mechanism is omitted. The mechanism <NUM> further comprises a second frame or plate <NUM> that is rotatably mounted on the first frame <NUM> about an axis A5-A5 that is orthogonal to both the longitudinal and transverse directions of the tabletop <NUM>.

As used herein, the phrase "X rotatably mounted on Y about an axis Z" means X is mounted on Y and is rotatable relative to Y about axis Z.

The mechanism <NUM> further comprises first, second and third actuators <NUM>, <NUM>, <NUM>. The first frame <NUM> is connected to the first part <NUM> of the column <NUM> via the first actuator <NUM> and via the third actuator <NUM> in parallel to the first actuator <NUM>. In this context, "parallel" means parallel in the sense of physical topology, rather than geometrically parallel. No further actuators connect the first frame <NUM> to the column <NUM>, so the total number of actuators via which the first frame <NUM> is connected to the column <NUM> is only two. The second frame <NUM> is connected to the first part <NUM> of the column <NUM> via the second actuator <NUM>. No further actuators connect the second frame <NUM> to the column <NUM>, so the total number of actuators via which the second frame <NUM> is connected to the column <NUM> is only one.

The first and third actuators <NUM>, <NUM> are for moving the first frame <NUM> relative to the column <NUM> about the transverse axis of the tabletop <NUM>, which is parallel to the transverse direction of the tabletop <NUM>. The second actuator <NUM> is for moving the second frame <NUM> relative to the column <NUM> about the longitudinal axis of the tabletop <NUM>, which is parallel to the longitudinal direction of the tabletop <NUM>. Due to the second frame <NUM> being mounted on the first frame <NUM>, each of the first, second and third actuators <NUM>, <NUM>, <NUM> actually is for moving both the first and second frames <NUM>, <NUM> relative to the column <NUM> about one or other of the transverse and longitudinal axes of the tabletop <NUM>.

The first frame <NUM> is connected to the first and third actuators <NUM> by a first gimbal mechanism <NUM> and the second frame <NUM> is connected to the second actuator <NUM> by a second gimbal mechanism <NUM>. The first gimbal mechanism <NUM> is configured to rotate the tabletop <NUM> about an axis parallel to the transverse direction of the tabletop (i.e. in a Trendelenburg or reverse Trendelenburg movement) and the second gimbal mechanism <NUM> is configured to rotate the tabletop <NUM> about an axis parallel to the longitudinal direction of the tabletop <NUM> (i.e. in a tilt movement in either a left or right direction relative to the longitudinal direction of the tabletop <NUM>).

The first actuator <NUM> comprises a cylinder 101a rotatably connected to a first side of the column <NUM> about only a single first axis A1-A1, and an elongate part 101b movably disposed within the cylinder 101a and connected to a first end portion of the first frame <NUM> via a first universal joint 101c. The third actuator <NUM> comprises a cylinder 103a rotatably connected to a third side of the column <NUM> about only a single third axis A3-A3 spaced from and parallel to the first axis A1-A1, and an elongate part 103b movably disposed within the cylinder 103a and connected to a second end portion of the first frame <NUM> via a third universal joint 103c. The third side of the column <NUM> is opposed to the first side of the column <NUM>, and the first and second end portions of the first frame <NUM> are opposite end portions of the first frame <NUM>.

Similarly, the second actuator <NUM> comprises a cylinder 102a rotatably connected to a second side of the column <NUM> about only a second axis A2-A2 that is orthogonal to the first and third axes A1-A1, A3-A3, and an elongate part 102b movably disposed within the cylinder 102a and connected to a first end portion of the second frame <NUM> via a second universal joint 102c. The first and third axes A1-A1, A3-A3 are parallel to the transverse direction of the tabletop <NUM> and the second axis A2-A2 is parallel to the longitudinal direction of the tabletop <NUM>. Each of the actuators <NUM>, <NUM>, <NUM> preferably comprises an electric motor for moving the elongate part of the actuator relative to the cylinder of the actuator.

The mechanism <NUM> further comprises first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM>. The first frame <NUM> is connected to the first part <NUM> of the column <NUM> via the first and third extensible stabilisers <NUM>, <NUM> in parallel with the first and third actuators <NUM>, <NUM>, and the second frame <NUM> is connected to the first part <NUM> of the column <NUM> via the second and fourth extensible stabilisers <NUM>, <NUM> in parallel with the second actuator <NUM>. In this context, "parallel" means parallel in the sense of physical topology, rather than geometrically parallel. The total number of extensible stabilisers via which the first frame <NUM> is connected to the column <NUM> is only two, and the total number of extensible stabilisers via which the second frame <NUM> is connected to the column <NUM> is only two. It is to be noted that all of the first to third actuators <NUM> to <NUM> are disposed outside all of the first to fourth extensible stabilisers <NUM> to <NUM>.

The first extensible stabiliser <NUM> comprises a cylinder 111a rotatably connected to the first side of the column <NUM> about only a single axis spaced from and parallel to the first axis A1-A1, and an elongate part 111b movably disposed within the cylinder 111a and connected to the first end portion of the first frame <NUM> via the first universal joint 101c. In particular, the elongate part 111b of the first extensible stabiliser <NUM> is connected to the elongate part 101b of the first actuator <NUM> via a first rotatable joint <NUM>, which first rotatable joint <NUM> permits relative rotation of the elongate part 111b of the first extensible stabiliser <NUM> and the elongate part 101b of the first actuator <NUM>. The third extensible stabiliser <NUM> comprises a cylinder 113a rotatably connected to the third side of the column <NUM> about only a single axis spaced from and parallel to the third axis A3-A3, and an elongate part 113b movably disposed within the cylinder 113a and connected to the second end portion of the first frame <NUM> via the third universal joint 101c. In particular, the elongate part 113b of the third extensible stabiliser <NUM> is connected to the elongate part 103b of the third actuator <NUM> via a third rotatable joint <NUM>, which third rotatable joint <NUM> permits relative rotation of the elongate part 113b of the third extensible stabiliser <NUM> and the elongate part 103b of the third actuator <NUM>.

Similarly, the second extensible stabiliser <NUM> comprises a cylinder 112a rotatably connected to the second side of the column <NUM> about only a single axis spaced from and parallel to the second axis A2-A2, and an elongate part 112b movably disposed within the cylinder 112a and connected to the first end portion of the second frame <NUM> via the second universal joint 102c. In particular, the elongate part 112b of the second extensible stabiliser <NUM> is connected to the elongate part 102b of the second actuator <NUM> via a second rotatable joint <NUM>, which second rotatable joint <NUM> permits relative rotation of the elongate part 112b of the second extensible stabiliser <NUM> and the elongate part 102b of the second actuator <NUM>. The fourth extensible stabiliser <NUM> comprises a cylinder 114a rotatably connected to a fourth side of the column <NUM> about only a single fourth axis A4-A4 spaced from and parallel to the second axis A2-A2, and an elongate part 114b movably disposed within the cylinder 114a and connected to a second end portion of the second frame <NUM> via a fourth universal joint 104c. The fourth side of the column <NUM> is opposed to the second side of the column <NUM>, and the first and second end portions of the second frame <NUM> are opposite end portions of the second frame <NUM>.

In variations to this embodiment, the first extensible stabiliser <NUM> is rotatably connected to the column <NUM> about only the first axis A1-A1, and/or the second extensible stabiliser <NUM> is rotatably connected to the column <NUM> about only the second axis A2-A2, and/or the third extensible stabiliser <NUM> is rotatably connected to the column <NUM> about only the third axis A3-A3, and/or the fourth extensible stabiliser <NUM> is rotatably connected to the column <NUM> about only a single axis spaced from and parallel to the fourth axis A4-A4.

In <FIG>, all of the first, second and third actuators <NUM>, <NUM>, <NUM> are fully contracted, i.e. extended to a minimum extent. Likewise, all of the first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> are fully contracted, i.e. extended to a minimum extent. In such a state, the mechanism <NUM> is at its minimum height. In comparison, in <FIG>, all of the first, second and third actuators <NUM>, <NUM>, <NUM> have been extended to their maximum extents, which in turn causes extension of the first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM>. In such a state, the mechanism <NUM> is at its maximum height. Accordingly, it will be appreciated that extension of all of the first, second and third actuators <NUM>, <NUM>, <NUM> increases the height of the mechanism <NUM> (i.e. increases the distance between the column <NUM> and the tabletop <NUM>), thereby increasing the height of the tabletop <NUM> above the column <NUM> and above the base <NUM>.

Selectively extending or contracting the first to third actuators <NUM>, <NUM>, <NUM> causes the tabletop <NUM> to become inclined relative to the column <NUM> and relative to the horizontal about the transverse and/or longitudinal axes of the tabletop <NUM>.

For example, in <FIG>, the first actuator <NUM> and first extensible stabiliser <NUM> are fully extended, the third actuator <NUM> and third extensible stabiliser <NUM> are fully contracted, and the second actuator <NUM> and the second and fourth extensible stabiliser <NUM>, <NUM> are partially extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a positive angle of <NUM> degrees about the transverse axis of the tabletop <NUM> at a maximum Trendelenburg position. Contrastingly, in <FIG>, the first actuator <NUM> and first extensible stabiliser <NUM> are fully contracted, the third actuator <NUM> and third extensible stabiliser <NUM> are fully extended, and the second actuator <NUM> and the second and fourth extensible stabilisers <NUM>, <NUM> remain partially extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a negative angle of <NUM> degrees about the transverse axis of the tabletop <NUM> at a minimum Trendelenburg position, i.e. at a maximum reverse-Trendelenburg position.

In <FIG>, the second actuator <NUM> and second extensible stabiliser <NUM> are nearly fully extended, the fourth extensible stabiliser <NUM> is nearly fully contracted, and the first and third actuators <NUM>, <NUM> and the first and third extensible stabilisers <NUM>, <NUM> are partially extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a positive angle of <NUM> degrees about the longitudinal axis of the tabletop <NUM> at a maximum left hand tilt. Contrastingly, in <FIG>, the second actuator <NUM> and second extensible stabiliser <NUM> are nearly fully contracted, the fourth extensible stabiliser <NUM> is nearly fully extended, and the first and third actuators <NUM>, <NUM> and the first and third extensible stabilisers <NUM>, <NUM> remain partially extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a negative angle of <NUM> degrees about the longitudinal axis of the tabletop <NUM> at a maximum right hand tilt.

It is possible also to incline the tabletop <NUM> about both the transverse and longitudinal axes of the tabletop <NUM> simultaneously. Doing so causes relative rotation of the first and second frames <NUM>, <NUM> about the axis A5-A5 orthogonal to both the longitudinal and transverse directions of the tabletop <NUM> as shown in each of <FIG>, as compared to their relative position when the first, second and third actuators <NUM>, <NUM>, <NUM> are all extended or contracted to the same degree, as shown in each of <FIG>.

As shown in <FIG>, the first actuator <NUM> and the first extensible stabiliser are fully extended, the second actuator <NUM> and the second extensible stabiliser <NUM> are nearly fully extended, the third actuator <NUM> and the third extensible stabiliser <NUM> are fully contracted, and the fourth extensible stabiliser <NUM> is nearly fully contracted. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at positive angles about both the transverse and longitudinal axes of the tabletop <NUM>. As shown in <FIG>, the first actuator <NUM> and the first extensible stabiliser are fully contracted, the second actuator <NUM> and the second extensible stabiliser <NUM> are nearly fully contracted, the third actuator <NUM> and the third extensible stabiliser <NUM> are fully extended, and the fourth extensible stabiliser <NUM> is nearly fully extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at negative angles about both the transverse and longitudinal axes of the tabletop <NUM>. As shown in <FIG>, the first actuator <NUM> and the first extensible stabiliser are nearly fully extended, the second actuator <NUM> and the second extensible stabiliser <NUM> are fully extended, the third actuator <NUM> and the third extensible stabiliser <NUM> are fully contracted, and the fourth extensible stabiliser <NUM> is nearly fully extended. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a positive angle about the transverse axis of the tabletop <NUM> and at a negative angle about the longitudinal axis of the tabletop <NUM>. As shown in <FIG>, the first actuator <NUM> and the first extensible stabiliser are fully contracted, the second actuator <NUM> and the second extensible stabiliser <NUM> are nearly fully extended, the third actuator <NUM> and the third extensible stabiliser <NUM> are fully extended, and the fourth extensible stabiliser <NUM> is nearly fully contracted. This causes the tabletop <NUM> to be inclined relative to the column <NUM> and base <NUM> and relative to the horizontal at a negative angle about the transverse axis of the tabletop <NUM> and at a positive angle about the longitudinal axis of the tabletop <NUM>.

Naturally, the degree of extension of each of the three actuators <NUM>, <NUM>, <NUM> can be selected to position the tabletop <NUM> at a desired degree and direction of inclination relative to the column <NUM> and base <NUM> and relative to the horizontal, or to position the tabletop <NUM> parallel to the horizontal.

Since a distance between the first and second plates <NUM>, <NUM> and the column <NUM> is increasable by extending all of the first, second and third actuators <NUM>, <NUM>, <NUM> (and all of the first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM>), it is possible to incline the tabletop <NUM> relative to the column <NUM> over a greater range of angles, as compared to a comparable table in which it is not possible to increase a distance between the first and second plates <NUM>, <NUM> and the column <NUM>. Accordingly, the table <NUM> is provided with increased versatility as compared to the comparable table.

Moreover, since in the illustrated embodiment the first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> are provided in parallel to the first, second and third actuators <NUM>, <NUM>, <NUM>, the extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> are able to help withstand lateral loading of the table <NUM>. Accordingly, the first, second and third actuators <NUM>, <NUM>, <NUM> can be made less robust (laterally, at least) than the actuators of a comparable table in which the extensible stabilisers are omitted.

The provision of the extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> minimises lateral loading acting on the actuators <NUM>, <NUM>, <NUM>, by resisting unwanted rotational movement of the assembly of the first and second frames <NUM>, <NUM>. Lateral loading is significant in operating tables as a result of typically high offset loads and twisting torques that can be applied to the tabletop <NUM>. The extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> effectively act as an exoskeleton that ensures that actuator loading is only compressive and substantially in line with the longitudinal axes of the actuators <NUM>, <NUM>, <NUM>. The provision of the extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> is highly desired, because the assembly of the tabletop <NUM> and the first and second frames <NUM>, <NUM> is not connected directly to the column <NUM> as per some conventional operating tables. In the table <NUM> of the present embodiment, the trend and tilt rotation axes are effectively floating above the column <NUM>. Moreover, in embodiments in which each of the actuators <NUM>, <NUM>, <NUM> comprises a ball screw and a ball screw nut connection to a gearbox, there is inherent lateral movement or free play within each of the actuators <NUM>, <NUM>, <NUM> that could contribute to unwanted tabletop <NUM> movement, since this effect is magnified at the tabletop <NUM>. The provision of the extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> reduces or eliminates this free play or unwanted movement of the tabletop <NUM>.

However, in a variation to the illustrated embodiment, the first, second, third and fourth extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> may be omitted and the first, second and third actuators <NUM>, <NUM>, <NUM> made more robust (laterally, at least). In another variation to the illustrated embodiment, only the first, second and third extensible stabilisers <NUM>, <NUM>, <NUM> may be omitted and the first, second and third actuators <NUM>, <NUM>, <NUM> made more robust (laterally, at least). In the illustrated embodiment, and even in such variations to the illustrated embodiment, the first and third actuators <NUM>, <NUM> arranged in a first plane counteract lateral loads against the second actuator <NUM> and the fourth extensible stabiliser <NUM> arranged in a second plane orthogonal to the first plane. Similarly, the second actuator <NUM> and the fourth extensible stabiliser <NUM> arranged in the second plane counteract lateral loads against the first and third actuators <NUM>, <NUM> arranged in the first plane.

In the illustrated embodiment, there are provided four extensible stabilisers <NUM>, <NUM>, <NUM>, <NUM> but only three actuators <NUM>, <NUM>, <NUM>, since it has been found that the table <NUM> is robust enough to perform the required tilting movements of the tabletop <NUM> using only the single second actuator <NUM>. Accordingly, the table <NUM> is cheaper to manufacture, more reliable and less complex to control than a comparable table with four actuators. However, in a variation to the illustrated embodiment, a fourth actuator may be provided, comprising a cylinder rotatably connected to the fourth side of the column <NUM> about only the single fourth axis A4-A4 or an axis spaced from and parallel to the fourth axis A4-A4, and an elongate part movably disposed within the cylinder and connected to the second end portion of the second frame <NUM> via the fourth universal joint 104c. The elongate part 114b of the fourth extensible stabiliser <NUM> may be connected to the elongate part of the fourth actuator via a fourth rotatable joint (not shown), which fourth rotatable joint would permit relative rotation of the elongate part 114b of the fourth extensible stabiliser <NUM> and the elongate part of the fourth actuator. Such a fourth actuator would be disposed outside all of the first to fourth extensible stabilisers <NUM> to <NUM>.

In another aspect, a surgical table is provided with an alternative mechanism for adjusting a height of a tabletop thereof.

In this embodiment, the column height adjustment system <NUM> comprises the column actuator <NUM>, and a mechanism height adjustment system comprises the first, second and third actuators <NUM>, <NUM>, <NUM> of the mechanism <NUM>.

As discussed above, extension of the column actuator <NUM> increases the height of the column <NUM> until the column <NUM> reaches its maximum height (not shown) when the first, second and third tubes <NUM>, <NUM>, <NUM> are un-nested to the maximum possible extent. This maximum height of the column <NUM> will be referred to for the present discussion as a first maximum height. Conversely, contraction of the column actuator <NUM> decreases the height of the column <NUM> until the column <NUM> reaches its minimum height (see <FIG>) when the first, second and third tubes <NUM>, <NUM>, <NUM> are nested together to the maximum possible extent. This minimum height of the column <NUM> will be referred to for the present discussion as a first minimum height. A difference between the first minimum height and the first maximum height, i.e. the total height or length by which the column <NUM> is extendible, is referred to as a first range.

As also discussed above, extension of all of the first, second and third actuators <NUM>, <NUM>, <NUM> increases the height of the mechanism <NUM> until the mechanism <NUM> reaches its maximum height (see <FIG>), which will be referred to for the present discussion as a second maximum height. Conversely, contraction of all of the first, second and third actuators <NUM>, <NUM>, <NUM> decreases the height of the mechanism <NUM> until the mechanism <NUM> reaches its minimum height (see <FIG>), which will be referred to for the present discussion as a second minimum height. A difference between the second minimum height and the second maximum height, i.e. the total height or length by which the mechanism <NUM> is extendible, is referred to as a second range.

In the present embodiment, the total height or length by which the column <NUM> is extendible is greater than the total height or length by which the mechanism <NUM> is extendible. That is, the first range is greater than the second range. Specifically, in the present embodiment, the total height or length by which the column <NUM> is extendible is approximately <NUM> millimetres, while the total height or length by which the mechanism <NUM> is extendible is approximately <NUM> millimetres. Accordingly, a ratio of the first range to the second range is approximately <NUM>:<NUM> (<NUM> to <NUM>).

Of course, in variations to this embodiment the values of the first and second ranges may vary. For example, preferably the first range is between <NUM> and <NUM> millimetres, and preferably the second range is between <NUM> and <NUM> millimetres. Regardless as to the specific values of the first and second ranges, preferably a ratio of the first range to the second range is between <NUM>:<NUM> and <NUM>:<NUM>, and more preferably the ratio is between <NUM>:<NUM> and <NUM>:<NUM>.

Moreover, in the present embodiment a controller <NUM> (see <FIG>) of the table <NUM> is communicatively connected to the column actuator <NUM> of the column height adjustment system <NUM> and communicatively connected to the first, second and third actuators <NUM>, <NUM>, <NUM> of the mechanism height adjustment system. The controller <NUM> is configured to control the column height adjustment system <NUM> and the mechanism height adjustment system, for example to adjust the overall height of the tabletop <NUM> above the base <NUM> and floor <NUM>, in dependence on one or more instructions received at the controller <NUM> from a user interface <NUM> (see <FIG>) of the table <NUM>. The user interface <NUM> may be attached to the table <NUM> or may be provided in a portable handset communicatively connected to components of the table <NUM>.

The controller <NUM> is configured to control the mechanism height adjustment system to adjust the height of the mechanism <NUM>, and thereby to adjust the overall height of the tabletop <NUM> above the base <NUM> and floor <NUM>, only when the height of the column <NUM> is one of the first minimum height and the first maximum height. Thus, when the overall height of the tabletop <NUM> is some way between the minimum and maximum overall heights, and when the column <NUM> is not at either of the first minimum and first maximum heights, on receipt at the controller <NUM> from the user interface <NUM> of an instruction to increase or decrease the overall height of the tabletop <NUM>, the controller <NUM> is configured to first control the column actuator <NUM> of the column height adjustment system <NUM> to increase or decrease, respectively, the height of the column <NUM>. If the controller <NUM> continues to receive from the user interface <NUM> an instruction to increase or decrease, respectively, the overall height of the tabletop <NUM> when the column <NUM> reaches the first maximum height or the first minimum height, respectively, the controller <NUM> is configured then to control the first, second and third actuators <NUM>, <NUM>, <NUM>, as required, of the mechanism height adjustment system to increase or decrease, respectively, the height of the mechanism <NUM>.

Looked at another way, when the overall height of the tabletop <NUM> is at the maximum overall height or the minimum overall height, on receipt at the controller <NUM> from the user interface <NUM> of an instruction to decrease or increase, respectively, the overall height of the tabletop <NUM>, the controller <NUM> is configured first to control the first, second and third actuators <NUM>, <NUM>, <NUM>, as required, of the mechanism height adjustment system to decrease or increase, respectively, the height of the mechanism <NUM> to a height (preferably a mid-point) between the second minimum and maximum heights. If the controller <NUM> continues to receive from the user interface <NUM> an instruction to decrease or increase, respectively, the overall height of the tabletop <NUM> when the mechanism <NUM> reaches the height between the second minimum and maximum heights, the controller <NUM> is configured then to control the column actuator <NUM> of the column height adjustment system <NUM> to decrease or increase, respectively, the height of the column <NUM>, while maintaining the height of the mechanism <NUM> at the height between the second minimum and maximum heights. If the controller <NUM> continues to receive from the user interface <NUM> an instruction to decrease or increase, respectively, the overall height of the tabletop <NUM> when the column <NUM> reaches the first minimum height or the first maximum height, respectively, the controller <NUM> is configured then to again control the first, second and third actuators <NUM>, <NUM>, <NUM>, as required, of the mechanism height adjustment system to decrease or increase, respectively, the height of the mechanism <NUM> further towards the second minimum height or the second maximum height, respectively.

Accordingly, when adjusting the overall height of the tabletop <NUM> above the base <NUM> and floor <NUM> between the minimum overall height of the tabletop <NUM> (when the column <NUM> is at the first minimum height and the mechanism <NUM> is at the second minimum height) and the maximum overall height of the tabletop <NUM> (when the column <NUM> is at the first maximum height and the mechanism <NUM> is at the second maximum height), a majority of the change in height of the tabletop <NUM> above the base <NUM> and floor <NUM> is effected through operation of the column actuator <NUM> of the column height adjustment system <NUM>. As such, the column actuator <NUM> can be made much more robust than the first, second and third actuators <NUM>, <NUM>, <NUM> of the mechanism height adjustment system, which permits the first, second and third actuators <NUM>, <NUM>, <NUM> to be small. Reducing the size of the first, second and third actuators <NUM>, <NUM>, <NUM> lowers a centre of mass of the table <NUM>, which in turn increases stability of the table <NUM>, and frees up space between the tabletop <NUM> and the column <NUM>, which facilitates access to the top of the column <NUM> and underside of the tabletop <NUM> for maintenance.

Moreover, as discussed above, the first, second and third actuators <NUM>, <NUM>, <NUM> are used to adjust the tilt and trend of the tabletop <NUM>. A greater degree of tilt and/or trend of the tabletop <NUM> is possible when the first, second and third actuators <NUM>, <NUM>, <NUM> are not fully extended or fully contracted. As also discussed above, when adjusting the overall height of the tabletop <NUM>, the height of the mechanism <NUM> is first adjusted to a height (preferably a mid-point) between the second minimum and maximum heights, before the height of the column <NUM> is adjusted. Accordingly, a high degree of tilt and/or trend of the tabletop <NUM> is possible over a greater range of the overall height of the tabletop <NUM>, as compared to a comparable table in which the height of the mechanism <NUM> is adjusted to one of the second minimum and maximum heights before the height of the column <NUM> is adjusted, when adjusting the overall height of the tabletop <NUM>.

In variations to the illustrated embodiment, the table <NUM> comprises a lock mechanism for selectively fixing a height of the mechanism <NUM> at one of the second minimum height, the second maximum height, and a height between the second minimum height and the second maximum height. In such a variation, any adjustment in the overall height of the tabletop <NUM> is effected only through adjustment of the height of the column <NUM> when the height of the mechanism <NUM> is fixed through actuation of the lock mechanism. In effect, when actuated, such a lock mechanism acts to prevents the controller <NUM> from controlling the first, second and third actuators <NUM>, <NUM>, <NUM>, as required, to adjust the height of the mechanism <NUM> and the overall height of the tabletop <NUM>, while still permitting the controller <NUM> to adjust of the height of the first, second and third actuators <NUM>, <NUM>, <NUM>, as required, to effect tilting and/or trending of the tabletop <NUM>, and still permitting the controller <NUM> to control the column actuator <NUM> of the column height adjustment system <NUM> to decrease or increase, respectively, the height of the column <NUM>, thereby to adjust the overall height of the tabletop <NUM>. When the lock mechanism is for selectively fixing the height of the mechanism <NUM> at the second minimum height, the table <NUM> is more stable. When the lock mechanism is for selectively fixing the height of the mechanism <NUM> at the height between the second minimum height and the second maximum height, then it is better ensured that a great degree of tilt and/or trend of the tabletop <NUM> is possible through subsequent actuation of the first, second and third actuators <NUM>, <NUM>, <NUM>, as required.

In another aspect, each of the first, second and third extensible stabilisers <NUM>, <NUM>, <NUM> may comprise a respective sensor, and the controller <NUM> may be configured to control the first, second and third actuators <NUM>, <NUM>, <NUM>, respectively, to adjust a length of the first, second and third actuators <NUM>, <NUM>, <NUM>, respectively, on the basis of an output of the respective sensors. For example, with reference to the first actuator <NUM> and the first extensible stabiliser <NUM>, one of the cylinder 111a and the elongate part 111b of the first extensible stabiliser <NUM> may comprise a magnet, and the other of the cylinder 111a and the elongate part 111b of the first extensible stabiliser <NUM> may comprise a sensor, e.g. a hall effect sensor or a reed switch, configured to detect a magnetic field of the magnet. The controller <NUM> may be configured to control the first actuator <NUM> to adjust a length of the first actuator <NUM> on the basis of the output of the sensor, e.g. so as to avoid the elongate part 101b of the first actuator <NUM> being driven so far into the cylinder 101a of the first actuator <NUM> that the first rotatable joint <NUM> is brought into contact with the cylinder 101a of the first actuator <NUM>, which could otherwise damage the cylinder 101a of the first actuator <NUM>, the first rotatable joint <NUM>, or the electric motor of the first actuator <NUM>. Providing the sensors in the extensible stabilisers rather than in the actuators avoids having to modify, and possibly weaken, the actuators.

In another aspect, a surgical table is provided with one or more assistance mechanisms for helping medical staff using the surgical table to dispose a tabletop and a base of the surgical table at a predetermined relative position. Such a predetermined relative position may be, for example, the position at which a patient is most easily transferrable onto or from the table, or the position at which the tabletop and the base are best placed to enable a certain procedure to be performed on a patient supported by the table.

As discussed above, in the present embodiment a height of the tabletop <NUM> is adjustable in a vertical direction relative to the base <NUM>, and the tabletop <NUM> also is traversable relative to the base <NUM> in the longitudinal direction of the tabletop <NUM>, i.e. in the direction of the longitudinal axis of the tabletop <NUM>. The table <NUM> of the present embodiment includes assistance mechanisms for helping medical staff using the table <NUM> to dispose the tabletop <NUM> and the base <NUM> at respective predetermined relative positions, such as predetermined default or home positions.

There now follows a description of the construction and operation of such an assistance mechanism for helping medical staff using the table <NUM> to dispose the tabletop <NUM> at a predetermined overall height relative to the base <NUM>, i.e. at a position someway, e.g. midway, between the maximum and minimum overall heights relative to the base <NUM>. For the purposes of this discussion, the column actuator <NUM> and/or the first, second and third actuators <NUM>, <NUM>, <NUM> are considered as comprised in the tabletop drive mechanism, and the controller <NUM> controls the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> towards or away from the base <NUM> in the direction of the vertical axis V-V of the table <NUM>.

In dependence on movement instruction(s) received at the controller <NUM> from the user interface <NUM>, the controller <NUM> is configured to control the tabletop drive mechanism (or more specifically the column actuator <NUM> and/or the first, second and third actuators <NUM>, <NUM>, <NUM>, as required) to cause translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM> between the maximum and minimum overall heights via the predetermined overall height.

When the tabletop <NUM> is at the predetermined overall height relative to the base <NUM>, the controller <NUM> controls the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM> to be paused for a predetermined period of time. In this embodiment, the predetermined period of time is <NUM> seconds. However, in variations to this embodiment, the predetermined period of time may be any time between <NUM> and <NUM> seconds, more preferably between <NUM> and <NUM> seconds, more preferably between <NUM> and <NUM> seconds, and most preferably between <NUM> and <NUM> seconds. The controller <NUM> is configured such that, if after elapse of the predetermined period of time the controller <NUM> still is receiving from the user interface <NUM> the movement instruction(s) to control the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM>, then the controller <NUM> controls the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM> to be resumed. The controller <NUM> also is configured such that, if after elapse of the predetermined period of time the controller <NUM> no longer is receiving from the user interface <NUM> the movement instruction(s) to control the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM>, then the controller <NUM> controls the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the direction of the vertical axis V-V of the table <NUM> not to be resumed.

In this embodiment, the table <NUM> includes a sensor (not shown) communicatively connected to the controller <NUM> for sensing, and for notifying the controller <NUM>, when the tabletop <NUM> is at the predetermined overall height relative to the base <NUM>. The sensor could comprise a micro switch suitably connected to the one of the parts <NUM>, <NUM>, <NUM> of the column <NUM> so that a portion of another of the parts <NUM>, <NUM>, <NUM> of the column <NUM> is configured to actuate the micro switch when the tabletop <NUM> is at the predetermined overall height relative to the base <NUM>. In variations to this embodiment, the sensor could take forms other than a micro switch and/or could comprise components located at different places on the table <NUM>.

In variations to this embodiment, the controller <NUM> may determine when the tabletop <NUM> is at the predetermined overall height relative to the base <NUM> by a mechanism other than such a sensor. For example, the controller <NUM> may make the determination based on time elapsed since the tabletop <NUM> began moving from one or other of the maximum and minimum overall heights at a known speed, or (in embodiments in which respective first parts of the first, second, third and column actuators <NUM>, <NUM>, <NUM>, <NUM> rotate relative to respective second parts of the first, second, third, and column actuators <NUM>, <NUM>, <NUM>, <NUM> during extension or contraction of the first, second, third and column actuators <NUM>, <NUM>, <NUM>, <NUM>) based on the number of detected rotations of the first part of one of the first, second, third or column actuators <NUM>, <NUM>, <NUM>, <NUM> relative to the second part of the one of the first, second, third or column actuators <NUM>, <NUM>, <NUM>, <NUM> since the tabletop <NUM> began moving from one or other of the maximum and minimum overall heights.

It will thus be appreciated that, through the provision of the above-described assistance mechanism, users of the surgical table are alerted as to when the tabletop is at the predetermined overall height relative to the base, and are given the predetermined period of time in which to cause the user interface to stop sending the movement instruction(s) to the controller. Thus, there is provided a mechanism for helping users of the surgical table to dispose the tabletop of the surgical table at the predetermined overall height relative to the base.

It will be appreciated that the construction and operation of another such assistance mechanism of the surgical table <NUM> for helping medical staff dispose the tabletop <NUM> at a predetermined traverse position relative to the base <NUM>, i.e. at a position someway, e.g. midway, between the first and second traverse positions relative to the base <NUM> is similar. In such another assistance mechanism, the tabletop traverse mechanism is considered as comprised in the tabletop drive mechanism, and the controller <NUM> controls the tabletop drive mechanism to cause the translational movement of the tabletop <NUM> relative to the base <NUM> in the longitudinal direction of the tabletop <NUM>.

In variations to the illustrated embodiment, the surgical table may have none, or only either one, of the above-described assistance mechanisms.

In another aspect, a surgical table is provided with a system for monitoring the state of one or more electric actuators of the table.

In this embodiment, each of the first, second and third actuators <NUM>, <NUM>, <NUM> and the column actuator <NUM> is an electric actuator. As discussed above, the first, second and third actuators <NUM>, <NUM>, <NUM> and the column actuator <NUM> may be considered to be comprised in a drive mechanism, specifically a tabletop drive mechanism.

The surgical table <NUM> includes a power supply <NUM>, which is an electrical power supply comprising one or more cells or batteries or a connection to the mains electrical power supply. Each of the controller <NUM>, the user interface <NUM>, the first, second and third actuators <NUM>, <NUM>, <NUM> and the column actuator <NUM> is electrically connected to the power supply <NUM> for drawing electrical power from the power supply <NUM> in order to operate.

The table <NUM> further comprises a memory <NUM>, which preferably is non-volatile memory but may, in some embodiments, be volatile memory. In this embodiment, the memory <NUM> stores therein software for running by the controller <NUM> to control the mechanism height adjustment system and the column height adjustment system <NUM>, as discussed above, and indications of respective currents drawn from the power supply <NUM> by each of the first, second and third actuators <NUM>, <NUM>, <NUM> and the column actuator <NUM>.

The controller <NUM> comprises a current determiner for determining a current drawn from the power supply <NUM> by each of the first, second and third actuators <NUM>, <NUM>, <NUM> while the respective actuator <NUM>, <NUM>, <NUM> causes movement of the tabletop <NUM> relative to the column <NUM> and base <NUM>, in the various manners described above. The current determiner also is for determining a current drawn from the power supply <NUM> by the column actuator <NUM> while the column actuator <NUM> causes movement of the tabletop <NUM> and mechanism <NUM> relative to the base <NUM>, as also described above.

The controller <NUM> also comprises a recorder that is communicatively connected to the current determiner and the memory and is configured to record in the memory <NUM> an indication of a current determined by the current determiner in dependence on an output of the current determiner. By "communicatively connected to the current determiner", it is meant that the recorder is able to receive or determine the output of the current determiner. In practice, the controller <NUM> may comprise a (optionally unitary) microprocessor that is configured to carry out the operations of both the current determiner and the recorder.

The current determiner is configured to determine respective currents drawn from the power supply <NUM> by each of the actuators <NUM>, <NUM>, <NUM>, <NUM> at respective different times, and the recorder is configured to record in the memory <NUM> respective indications of the determined respective currents.

Preferably, the controller <NUM> further comprises an overload determiner that is configured to determine when one or more of the actuators <NUM>, <NUM>, <NUM>, <NUM> is, or has been, overloaded. In order to do this, the overload determiner either determines an output of one of the current determiner and the recorder, or accesses the respective indications of the determined respective currents stored in the memory <NUM>. If the output of one of the current determiner and the recorder, or an indication of a current drawn from the power supply <NUM> by one of the actuators <NUM>, <NUM>, <NUM>, <NUM> indicates that a current drawn from the power supply <NUM> by one of the actuators <NUM>, <NUM>, <NUM>, <NUM> is greater than a predetermined threshold current for that actuator <NUM>, <NUM>, <NUM>, <NUM>, then the overload determiner determines that the actuator <NUM>, <NUM>, <NUM>, <NUM> in question is overloaded, or has recently been overloaded. The table <NUM> includes an indicator, in the form of a visual or audible indicator, for indicating to a user when one of the actuators <NUM>, <NUM>, <NUM>, <NUM> is overloaded. The controller <NUM> controls the indicator in dependence on an output of the overload determiner, which the controller <NUM> receives from the overload determiner.

The controller <NUM> preferably further comprises a calculator that is configured to calculate a cumulative current drawn from the power supply <NUM> by each of the actuators <NUM>, <NUM>, <NUM>, <NUM> over a period of time. In order to do this, the calculator accesses the indications stored in the memory <NUM> to determine respective currents drawn from the power supply <NUM> by each of the actuators <NUM>, <NUM>, <NUM>, <NUM> at respective different times, and then sums the respective currents drawn over the period of time from the power supply <NUM> by each of the actuators <NUM>, <NUM>, <NUM>, <NUM>. The period of time may be for example <NUM> hour, <NUM> hours, <NUM> days, <NUM> month, <NUM> year, etc..

Since the table <NUM> includes this system for recording the currents drawn from the power supply <NUM> by the electric actuators <NUM>, <NUM>, <NUM>, <NUM>, a maintenance person may access the memory <NUM> via a communication interface (not shown) of the table <NUM>, to analyse the respective and cumulative currents drawn from the power supply <NUM> by the actuators <NUM>, <NUM>, <NUM>, <NUM>. By such analysis, the maintenance person may estimate how much wear has been endured by the actuators <NUM>, <NUM>, <NUM>, <NUM>, in order to determine when one or more of the actuators <NUM>, <NUM>, <NUM>, <NUM> might be about to fail. Moreover, in embodiments such as the illustrated embodiment, in which the table <NUM> comprises an overload determiner and an indicator <NUM>, a user of the table <NUM> is altered as to when one or more of the electric actuators <NUM>, <NUM>, <NUM>, <NUM> is overloaded, in order that the user can avoid further straining of the one or more actuators <NUM>, <NUM>, <NUM>, <NUM>.

In another aspect, a surgical table is provided with a system for monitoring relative movements of first and second parts of the table, such as for future determination of relative movements of the first and second parts that have taken place.

The table <NUM> comprises a non-contact movement determiner for determining relative movements of various pairs of first and second relatively moveable parts of the table <NUM>. For example, the movement determiner may be configured to determine rotational movement of the tabletop <NUM> relative to the column <NUM> about either or both of the transverse and longitudinal axes of the tabletop <NUM>, and/or to determine translational movement of the tabletop <NUM> relative to the column <NUM> in the direction of the vertical axis of the table <NUM>, and/or to determine translational movement of the tabletop <NUM> relative to the column <NUM> in the direction of the longitudinal axis of the tabletop <NUM>, and/or to determine translational movement of the first part <NUM> of the column <NUM> relative to the base <NUM> in the direction of the vertical axis of the table <NUM>.

By "non-contact" it is meant that the movement determiner is configured to determine the relative movements without being brought into contact with either of the relatively moveable parts, as compared to e.g. a mechanical trip-switch that needs to be brought into contact with a moving object in order to determined movement of the object.

In some embodiments, the movement determiner is communicatively connected to the controller <NUM> and is configured to determine relative movements of the various pairs of first and second relatively moveable parts on the basis of outputs (such as drive commands to the actuators <NUM>, <NUM>, <NUM>, <NUM>) of the controller <NUM>, which the movement determiner is configured to intercept. In other embodiments, the table <NUM> may comprise respective non-contact sensors (not shown) (such as proximity sensors or accelerometers) for sensing relative positions of the various pairs of first and second relatively movable parts, and the movement determiner is communicatively connected to the sensors and is configured to determine relative movements of the various pairs of first and second relatively moveable parts on the basis of outputs of the sensors, which the movement determiner receives from the sensors.

The recorder is communicatively connected to the movement determiner and is configured to record in the memory <NUM> indications of relative movements of the various pairs of first and second relatively movable parts in dependence on outputs of the movement determiner, which the recorder receives from the movement determiner. Again, similarly to above, "communicatively connected to the movement determiner", it is meant that the recorder is able to receive or determine the output of the movement determiner. In practice, the controller <NUM> may comprise a (optionally unitary) microprocessor that is configured to carry out the operations of both the movement determiner and the recorder.

The movement determiner is configured to determine respective relative movements of the various pairs of first and second relatively movable parts at respective different times, and the recorder is configured to record in the memory <NUM> respective indications of the determined respective relative movements.

The table <NUM> preferably further comprises a second indicator <NUM> for indicating to a user, in dependence on a content of the memory <NUM>, (a) a sequence of past relative movements of one or more of the various pairs of first and second relatively moveable parts, and/or (b) a last-performed relative movement of one or more of the various pairs of first and second relatively moveable parts. The second indicator may comprise a graphical display or a series of illuminable elements, for example. In order to do this, the controller <NUM> accesses the indications of relative movements stored in the memory <NUM>, and then controls the second indicator <NUM> to provide an appropriate indication in dependence on the indications of relative movements stored in the memory <NUM>.

Since the table <NUM> includes this system for recording the relative movements of the various pairs of first and second relatively moveable parts of the table <NUM>, a maintenance person may access the memory <NUM> via a communication interface (not shown) of the table <NUM>, to analyse the respective indications of relative movements stored in the memory <NUM>. By such analysis, the maintenance person may be able to determine which pair of first and second relatively moveable parts of the table <NUM> were moving relative to each other prior to or during a failure of the table <NUM>, which helps to determine a reason for such a table failure <NUM>. Moreover, in embodiments such as the illustrated embodiment, in which the table <NUM> comprises an example of the above-described second indicator <NUM>, a user of the table <NUM> or a maintenance person is more readily informed as to which pair of first and second relatively moveable parts of the table <NUM> were moving relative to each other prior to or during a failure of the table <NUM>.

Claim 1:
A surgical table comprising: a base (<NUM>) for standing on a floor;
a column (<NUM>) extending from the base;
a tabletop (<NUM>) providing a patient support surface; and
a mechanism (<NUM>) coupling the tabletop to the column and for enabling rotational movement of the tabletop relative to the column about two orthogonal axes, the mechanism comprising a first frame (<NUM>) connected to the tabletop, a second frame (<NUM>) rotatably mounted on the first frame, first and second extensible stabilisers, (<NUM>, <NUM>) and first and second actuators (<NUM>, <NUM>) disposed outside of both the first and second extensible stabilisers (<NUM>, <NUM>),
each actuator being connected to a respective one of the frames for moving the respective frame about a respective one of the two orthogonal axes;
wherein the first frame (<NUM>) is connected to the column via the first extensible stabiliser (<NUM>) and the first actuator (<NUM>) in parallel, and the second frame (<NUM>) is connected to the column by the second extensible stabiliser (<NUM>) and the second actuator (<NUM>) in parallel