Title of Invention	"A LIFTING UNIT FOR A DIAGNOSIS DEVICE"
Abstract	The invention relates to a lifting unit for a patient support (1). Said lifting unit comprises a base plate (23), a motor drive (20), a lifting drive driven by said motor drive and received in the base plate (23). Said lifting drive is adapted to carry out a lifting movement and a movement in the opposite direction. A triggering element is activated when the pressure exerted by the lifting drive on the base plate (23) falls below a defined minimum value. The movement of the lifting drive is stopped in response to the activation of the triggering element. If the patient support (1) collides with an obstacle during lifting, the pressure exerted by the lifting drive on the base plate is reduced. The reduced pressure is detected by the triggering element and the movement of the patient support is stopped.

Title of Invention

"A LIFTING UNIT FOR A DIAGNOSIS DEVICE"

Abstract

The invention relates to a lifting unit for a patient support (1). Said lifting unit comprises a base plate (23), a motor drive (20), a lifting drive driven by said motor drive and received in the base plate (23). Said lifting drive is adapted to carry out a lifting movement and a movement in the opposite direction. A triggering element is activated when the pressure exerted by the lifting drive on the base plate (23) falls below a defined minimum value. The movement of the lifting drive is stopped in response to the activation of the triggering element. If the patient support (1) collides with an obstacle during lifting, the pressure exerted by the lifting drive on the base plate is reduced. The reduced pressure is detected by the triggering element and the movement of the patient support is stopped.

Full Text	The invention relates to a lifting unit with protection, a patient support device comprising such a lifting unit and a diagnosis or treatment device comprising such a patient support device. In medical diagnostics and treatment, items of equipment are frequently used in which a patient is examined or treated using radiation and electromagnetic- or sound-waves. In such cases, x-rays, electron or particle beams, ultrasound waves or magnetic fields are used. Many of the aforementioned items of equipment include relatively heavy radiation and power sources and frequently comprise corresponding detectors too. The devices can frequently be positionable by means of correspondingly huge mechanical structures installed in the room, and in most cases it is not possible to achieve completely free three-dimensional positioning. Depending on the type of examination or treatment to be carried out, the item of equipment for diagnosis and/or therapy or the power source thereof can be moved into a certain spatial orientation and position with respect to the patient who is to be examined. The adjustment of the spatial configuration required is supported in particular by positionable items of equipment installed in the room. Because the positionability is generally always restricted, not every possible spatial configuration of the patient and device can be achieved, however. In addition to this, there is the fact that, according to the type of examination or treatment, a certain positioning of the patient may be required, for example, back or side position, head-down or standing, etc. Therefore it is the convention to use a patient support device with the aid of which the patient can be positioned with respect to the item of equipment. Simultaneous positionability of the item of equipment and of the patient increases the number of possible spatial configurations. A basic option for positioning a patient with the aid of a patient support device consists of a one- or two-dimensional shifting into a geodetically horizontal plane. For this purpose, patient support device tables which have a table top as a patient couch with a floating mounting are known. The floating mounting can be configured with or without linear guidance, resulting in a one-dimensional or two-dimensional adjustability of the couch. A further basic adjustment option can be provided for the height of the couch. For this purpose, the provision of a lifting device oriented in a geodetically vertical position is known, said device lifting or lowering the couch generally from below. The lifting device may include a hydraulic, pneumatic or electric-motor drive and have a parallelogram or spindle drive mechanism. Further positioning options can be achieved by making the couch capable of being tipped or tilted. By combining all the adjustment options, maximum free positionability of the couch and therefore of the patient can be achieved. In medical practice, apart from positionability, it is of particular importance that a patient is as unrestricted as possible and freely accessible. In the context of the treatment or examination, medical or technical professionals have to be able to approach the patient at any time. Therefore it is known in patient support devices for a foot part that is as narrow as possible and takes up little space to be provided to support the patient couch. It is usual for the height adjustment of the patient couch to be achieved using a lifting unit that is arranged in the foot part. Thus it is known, for example, for a scissor or double-scissor mechanism driven by a spindle drive to be provided in the foot part as a lifting unit. The scissor or double-scissor mechanism is typically connected by a solid bearing to a base plate of the patient support device. The spindle of the spindle drive forms a structural unit with a drive motor, said unit being connected in a fixed manner to the base plate. The aforementioned design can be configured to be as narrow as possible so that patients are easily accessible. A narrow foot part has the advantage that the patient couch that rests thereon projects beyond the extent of the foot part. Below the projecting areas of the patient couch a free space appears which becomes bigger when the patient couch is lifted and smaller when it is lowered. When it is lowered, the patient couch can collide with objects or people occupying the free space. Firstly, this endangers the equipment or in particular people occupying this space. Secondly, when the couch is raised, considerable tensile forces are exerted on the lifting unit that is connected to the base plate. These tensile forces can in the worst scenario lead to damage to the lifting unit. WO 01/49234 discloses a patient support device which includes a motorized lifting drive. IR barriers are provided on the patient support device, with the function of blocking or releasing a motorized movement. Furthermore, IR sensor means are provided to detect an impending collision of the patient support device with people or objects so that a motorized movement can be blocked in good time. US 2004/0094077 likewise discloses a patient support device which includes a motorized lifting drive. In order to be able to stop a motorized downward movement of the patient support device in good time, the patient support device has buttons on the base, the actuation of which stops the drive for the downward movement. The invention addresses the problem of providing a lifting unit that guarantees protection against people and equipment being endangered when the lifting unit is shortened. The invention further addresses the problem of providing a patient support device having a patient couch for an item of equipment for diagnosis and/or therapy and also an item of equipment for diagnosis and/or therapy comprising such a patient support device, which item of equipment guarantees protection against people and equipment being endangered when the lifting unit is lowered. The invention solves these problems by a lifting unit having the features of claim 1 or by a patient support device having the features of claim 9 or by an item of equipment for diagnosis and/or therapy having the features of claim 11. A basic concept of the invention consists in providing a lifting unit for an item of equipment for diagnosis and/or therapy , comprising a base plate, a motorized drive, a lifting drive that can be driven by said drive and which is mounted in the base plate, and which can carry out a lifting movement and a movement in the opposite direction, a triggering means being provided which is activated when the force exerted by the lifting drive on the base plate falls below a certain minimum value, the stopping of the movement being triggered in response to the triggering means being activated. If the lifting drive collides with an obstacle when the patient support device and/or item of equipment for diagnosis and/or therapy is shortened or lowered, this obviously leads to the force exerted thereby on the base plate being reduced. Thus, the stopping of movement triggered by a reduction in the force exerted protects the person or device about to be collided with since in fact the collision is prevented by stopping the movement. Here the maximum collision force obviously depends on the minimum value for the force exerted to activate the triggering means, combined with the total weight borne by the lifting drive. It is obtained by subtracting the total weight from said minimum value. Further basic concepts underlying the invention consist in providing a patient support device comprising the aforementioned lifting unit and also an item of equipment for diagnosis and/or therapy comprising a patient support device comprising the lifting unit described in the aforementioned. Further variants and advantages of the invention are defined in the dependent claims and in the description that follows of embodiments with reference to the Drawings, in which: FIG 1 shows a schematic diagram of an item of equipment for diagnosis and/or therapy comprising a patient support device, FIG 2 shows a schematic diagram of a scissor structure and spindle drive of a patient support device, FIG 3 shows a schematic diagram of the ball and socket bearing of the spindle drive, FIG 4 shows a schematic diagram of the lifting unit with triggering means in the form of a switch, FIG 5 shows a schematic diagram of the lifting unit with triggering means in the form of an electric contact, FIG 6 shows a schematic diagram of the lifting unit with triggering means in the form of a force or pressure transducer and FIG 7 shows a schematic diagram of the lifting unit with triggering means in the form of a light barrier. FIG 1 shows a diagram of an item of equipment for diagnosis and/or therapy (DT device) 3 comprising a patient support device 1. The DT device 3 includes a C-arm 31, which supports an x-ray source 33 and an x-ray detector 34. It can be used, for example, to generate x-ray images in cases of low energy x-ray radiation, or for therapeutic irradiation in cases of higher energy x-ray radiation. The C-arm 31 is housed in a C-arm stand 32. This can be a free-standing structure installed in the room or a structure that is fitted into a wall or ceiling of the room. The C-arm 31 allows the positioning of the x-ray source 33 and of the x-ray detector 34 in such a way that a patient positioned with the aid of the patient support device 1 can be detected by the x-ray beam. The patient support device 1 includes a couch 11 on which a patient can lie. The couch 11 can be moved in a horizontal direction, which is intended to be indicated by a horizontal two-headed arrow. For this purpose it is mounted onto a foot 12 with a floating mounting. Furthermore, the height of the couch can be adjusted. For this purpose, the foot 12 includes a lifting device, which is not shown in greater detail in FIG 1. The height adjustment is indicated by a vertical two-headed arrow. FIG 2 shows in schematic form components of the lifting device of the patient support device 1. The lifting device comprises a base plate 23, which is arranged in or integrated in the foot 12, on which base plate a double-scissor mechanism 13, that is, a structure consisting of two individual scissor mechanisms arranged one on top of the other, is mounted. The double-scissor mechanism 13 is vertically oriented in the sense that it is shortened or lengthened in a vertical direction when actuated. The shortening or lengthening of the double-scissor mechanism 13 provides height adjustment of the lifting plate 22 that is mounted thereon. Connected to the lifting plate 22 is the couch 11, such that the double-scissor mechanism 13 provides height adjustment of the couch 11 and thus of a patient lying thereon. The double-scissor mechanism 13 is mounted in a solid bearing 21 on the base plate 23. On the opposite side it is mounted in the base plate with a non-locating bearing 16, which includes, for example, a sliding bearing 15. The combination of the solid bearing 21 with the non-locating bearing 16 makes it possible to actuate the double-scissor mechanism 13. In order to be moveable against the lifting plate 22, said plate is mounted on the double-scissor mechanism 13 by means of a non-locating bearing 17, which includes, for example, a sliding bearing 14 on the lifting plate 22. Above the solid bearing 21, the double-scissor mechanism 13 can be connected to the lifting plate 22 by a further solid bearing which is not shown in further detail in the FIG. The actuation of the double-scissor mechanism 13 is achieved by means of a spindle drive. The spindle drive includes a spindle nut 18 connected to the double scissor mechanism 13 and also a spindle 19. By rotating the spindle 19 or the spindle nut 18, the height of the spindle nut 18 is adjusted and thus the length of the double-scissor mechanism 13 is adjusted. The rotation of the spindle 19 or of the spindle nut 18 is achieved by a drive 20, which is connected to the spindle 19 in such a way that it is able to rotate said spindle. The drive is typically an electric motor, but it could also be actuated hydraulically, pneumatically or manually or be foot-operated. FIG 3 shows details of the spindle drive in an embodiment that comprises a ball joint. It is possible to see the double-scissor mechanism 13 and the spindle nut 18, the connection point between the two not being shown. The spindle 19 or the spindle nut 18 is rigidly connected to the drive 20 such that the drive 20 can rotate the spindle 19 or the spindle nut 18. The structural unit formed by the drive 20 and the spindle 19 is mounted in the base plate 23 by means of a ball joint. For this reason, the base plate 23 has a bearing cup 27, which, in the embodiment shown, includes an elbow section having an angle of about 90°. The drive 20 and spindle 19 are mounted using a spherical head 26 and bearing cup 27. According to requirements, the spherical head 26 and the bearing cup 27 can consist of appropriate material, be hardened or have bearing cups or bearing surfaces that have the effect of reducing friction and wear. Such bearing surfaces are not shown in greater detail in FIG 3. If a torque is exerted on the double-scissor mechanism 13, for example as the result of an eccentric load on the couch 11 being exerted by a patient lying thereon or because of the eccentrically disposed drive 20, a torque is exerted on the couch 11 and via this onto the spindle drive, which torque can lead to errors in alignment of the spindle drive. The ball joint allows rotation of the spindle drive in such a way that said drive can yield to the torque and thus compensate for said errors in alignment. In this arrangement, the ball joint or the spindle drive can be configured in such a way that the spherical head 26 remains in the ball cup 27 even when the spindle drive is completely disengaged; it is also possible, however, to have a configuration which allows limited lifting of the spindle drive and thus a limited lifting of the spherical head 26 out of the ball cup 27. In the embodiment shown, the drive 20 is configured eccentrically with respect to the axis of rotation of the spindle 19. Thus it is also configured eccentrically with respect to the ball joint and thus, as a result of its weight, generates a torque of the spindle drive, this being in fact anti-clockwise in the figure. In order to counteract this torque, the drive 20 is mounted on sprung or elastic bearing elements, on rubber cushions 28 in fact. Instead of rubber cushions, other elastic bearing elements could also be used, for example, on the basis of steel spring elements. The rubber cushions 28 cause the bearing to be moveable by allowing movements of the drive around the ball joint to a slight extent. On the other hand, the rubber cushions 28 have the effect that the drive has self-supporting bearings from the start so that it does not exert any torque on the spindle drive. In other words, the rubber cushions 28 are dimensioned such that the drive 20 remains stable in the position shown. For this purpose, the rubber cushions 28 are likewise not arranged symmetrically round the ball joint but eccentrically such that the eccentric part of the bulk of the drive 20 is given greater support. The moveable bearings for the drive 20 have to be restricted insofar as the drive 20 exerts a rotational force on the spindle 19. For its part, the drive therefore has to be protected against rotation despite the fact that the bearings are moveable. This is achieved by a lug 25 which is firmly attached to the drive 20 and engages into an anti-twist device 24. The anti-twist device 24 is designed in such a way that although the drive 20 is prevented from rotating round the spindle 19, it can rotate round the ball joint as a result of an eccentric load being exerted on the couch 11 and thus can respond to a change in the alignment of the spindle drive. In this way, the bearings for the drive 20 and the spindle 19 ensure that errors in alignment between the spindle 19 and spindle nut 18 can be compensated for by the eccentric load on the couch 11. FIG 4 shows a schematic diagram of the lifting unit with triggering means in the form of a switch. The lifting unit is essentially similar to that described in the aforementioned. Instead of the bearing on rubber cushions 28, a connection to the base plate is provided by position-securing elements 102. These could be configured as threaded rods for example. The position-securing elements 102 have the effect that the lifting unit is fixed in a horizontal direction with respect to the base plate, whilst it is moveable to a slight extent in a vertical direction. Vertical mobility is indicated in the FIG by a vertical two-headed arrow to the right of the lifting unit. As soon as the freedom of motion of the position-securing elements 102 has been exhausted, the lifting unit is fixed in a vertical direction. The lifting unit can be shortened or lengthened in a vertical direction in order to raise or lower a couch or load that is supported thereby. When lowered, the load or couch may collide with an obstacle that prevents further lowering. In this case, the obstacle acts as a brake on the load or couch whilst the lifting unit is further shortened by the motorized drive without the above being taken into account. The further shortening of the lifting unit leads to it resting on the base plate with a decreasing weight. As soon as the weight has become sufficiently low, the lifting unit is raised and lifted off the base plate. The position-securing elements 102, which allow vertical movements of the lifting unit, do nothing to prevent this. In a further embodiment like that described in the aforementioned but not shown in greater detail in FIG 4 and in which the lifting unit is mounted on the base plate in a ball joint, this means that the spherical head of the ball joint is lifted out of the ball cup. As soon as the lifting unit is raised as described above, its lug touches the triggering means configured as a switch 25. In the process, the switch 25 is actuated and thus the triggering means is activated. As a result of the actuation of the switch 25, the drive of the lifting unit is switched off, so that a further shortening of the lifting unit or a further lowering of the couch or load is prevented. As a result, this obviously prevents a further increasing reduction in the load on the lifting unit and thus, as a consequence thereof, prevents there being an increasing load on the position-securing elements 102, which form the means of securing the lifting unit in the base plate. Furthermore, a further increase in the load on the obstacle that was collided with, for example a person or a device, is prevented. FIG 5 shows a schematic diagram of the lifting unit with triggering means in the form of an electric contact. Here the lifting unit is mounted on bearings 105 in such a way that is vertically moveable at least to a limited extent. The bearings 105 can be configured as rubber cushions as they are further above, or as spring elements or position-securing elements as described in the aforementioned. An electric contact 108 is provided under the spindle drive between the lifting unit and the base plate. Said contact is created by reciprocal contact between a contact means 107 located on the base plate and of a contact means 109 located on the lifting unit. The contact means 107, 109 can be configured as metallic contact elements. In particular, they can be configured as integrated bearings and contact means. When the lifting unit is raised from the base plate, as explained in the above description of FIG 4, the electric contact is interrupted. This interruption represents the activation of the triggering means and causes the drive of the lifting unit to be turned off. FIG 6 shows a schematic diagram of the lifting unit with triggering means in the form of a force or pressure transducer. Here the lifting unit is again mounted on bearings 105. A force or pressure transducer 110 is arranged under the spindle drive, said transducer measuring the supporting force exerted by the lifting unit on the base plate. If the force measured falls below a predetermined amount, the force or pressure transducer 110 is activated as a triggering means and causes the drive for the lifting unit to be turned off. FIG 7 shows a schematic diagram of the lifting unit with triggering means in the form of a light barrier 120. The light barrier 120 includes a lighting means 121 and a light sensor 122. Light generated by the lighting means 121 can reach the light sensor 122 along the path shown in the FIG by a dotted line. As long as the lifting unit is on the base plate, this path is interrupted by an extension 125 of the lifting unit as shown in the FIG. If the lifting unit is raised, as described in the aforementioned, then the extension 125 is lifted out of the light barrier 120. As a result, the extension is activated as a triggering means and causes the lifting unit drive to be turned off. In a further advantageous embodiment, after the activation of the respective triggering means, the lifting unit can be controlled in such a way that not only is further shortening prevented but that it is additionally lengthened again by a predetermined amount; in other words, not only is the lowering of the load or couch prevented but said couch is lifted again by a predetermined amount. As a result, not only is it possible to prevent a further increase in the load exerted as the unit is shortened but, furthermore, the load is immediately reduced again. This in particular is advantageous if there has been a collision with a sensitive device or even a person. The invention can be summarized as follows: the invention relates to a lifting unit for a patient support device 1, including a base plate 23, a motorized drive 20, a lifting drive that can be driven by said drive and which is mounted in the base plate 23, said lifting drive being able to carry out a lifting movement and a movement in the opposite direction, a triggering means being provided which is activated when the pressure exerted by the lifting drive on the base plate 23 falls below a pre-determined minimum value. The movement of the lifting drive is stopped in response to the activation of the triggering means. If the patient support device 1 collides with an obstacle as it is lowered, the pressure exerted by the lifting drive on the base plate is reduced. This event is detected by the triggering means and the movement of the patient support device is stopped. We Claim: 1. A lifting unit for a diagnosis device, a treatment device or a diagnosis and treatment device, the lifting unit comprising: a base plate, a motorized drive, a lifting drive operable to be driven by the motorized drive and provide a lifting movement in a direction opposite the base plate, the lifting drive being mounted on the base plate, and a triggering device configured as a power- or pressure transducer is arranged between the lifting drive and the base plate such that the triggering device is operable to detect when the lifting drive raises up from the base plate, the triggering device being configured to be activated when an electric contact interruption is detected as a result of the lifting drive raising up from the base plate, wherein the movement of the lifting drive is triggered to stop in response to the activation of the triggering device, and the electric contact is created by reciprocal contact between a first contact device located on the base plate and a second contact device located on the lifting device. 2 A lifting unit as claimed in claim 1, wherein the movement is stopped by interrupting the power connection between the drive(20) and the lifting drive, in particular by breaking a connection that is provided for this purpose. 3. A lifting unit as claimed in claim 1, wherein the movement of the lifting drive is stopped by switching off the drive. 4. A lifting unit as claimed in claim 1, wherein the lifting drive is coupled with a double-scissor mechanism that provides height of a lifting plate connected to a patient support. 5. A lifting unit as claimed in claim 1, wherein the motorized drive is an electric motor, hydraulically-actuated drive, pneumatically-actuated device, or foot- operated device. 6. A lifting unit as claimed in claim 1, comprising a power connection between the motorized drive and the lifting unit, the movement of the lifting drive being stopped when the power connection is interrupted.

Full Text

The invention relates to a lifting unit with protection, a patient support device comprising such a lifting unit and a diagnosis or treatment device comprising such a patient support device.
In medical diagnostics and treatment, items of equipment are frequently used in which a patient is examined or treated using radiation and electromagnetic- or sound-waves. In such cases, x-rays, electron or particle beams, ultrasound waves or magnetic fields are used. Many of the aforementioned items of equipment include relatively heavy radiation and power sources and frequently comprise corresponding detectors too. The devices can frequently be positionable by means of correspondingly huge mechanical structures installed in the room, and in most cases it is not possible to achieve completely free three-dimensional positioning.
Depending on the type of examination or treatment to be carried out, the item of equipment for diagnosis and/or therapy or the power source thereof can be moved into a certain spatial orientation and position with respect to the patient who is to be examined. The adjustment of the spatial configuration required is supported in particular by positionable items of equipment installed in the room. Because the positionability is generally always restricted, not every possible spatial configuration of the patient and device can be achieved, however. In addition to this, there is the fact that, according to the type of examination or treatment, a certain positioning of the patient may be required, for example, back or side position, head-down or standing, etc. Therefore it is the convention to use a patient support device with the aid of which the patient can be positioned with respect to the item of equipment. Simultaneous positionability of the item of equipment and of the patient increases the number of possible spatial configurations.
A basic option for positioning a patient with the aid of a patient support device consists of a one- or two-dimensional shifting into a geodetically horizontal plane.
For this purpose, patient support device tables which have a table top as a patient couch with a floating mounting are known. The floating mounting can be configured with or without linear guidance, resulting in a one-dimensional or two-dimensional adjustability of the couch. A further basic adjustment option can be provided for the height of the couch. For this purpose, the provision of a lifting device oriented in a geodetically vertical position is known, said device lifting or lowering the couch generally from below. The lifting device may include a hydraulic, pneumatic or electric-motor drive and have a parallelogram or spindle drive mechanism. Further positioning options can be achieved by making the couch capable of being tipped or tilted. By combining all the adjustment options, maximum free positionability of the couch and therefore of the patient can be achieved.
In medical practice, apart from positionability, it is of particular importance that a patient is as unrestricted as possible and freely accessible. In the context of the treatment or examination, medical or technical professionals have to be able to approach the patient at any time. Therefore it is known in patient support devices for a foot part that is as narrow as possible and takes up little space to be provided to support the patient couch.
It is usual for the height adjustment of the patient couch to be achieved using a lifting unit that is arranged in the foot part. Thus it is known, for example, for a scissor or double-scissor mechanism driven by a spindle drive to be provided in the foot part as a lifting unit. The scissor or double-scissor mechanism is typically connected by a solid bearing to a base plate of the patient support device. The spindle of the spindle drive forms a structural unit with a drive motor, said unit being connected in a fixed manner to the base plate. The aforementioned design can be configured to be as narrow as possible so that patients are easily accessible.
A narrow foot part has the advantage that the patient couch that rests thereon projects beyond the extent of the foot part. Below the projecting areas of the patient couch a free space appears which becomes bigger when the patient couch is lifted and smaller when it is lowered. When it is lowered, the patient couch can collide with objects or people occupying the free space. Firstly, this endangers the equipment or in particular people occupying this space. Secondly, when the couch is raised, considerable tensile forces are exerted on the lifting unit that is connected to the base plate. These tensile forces can in the worst scenario lead to damage to the lifting unit.
WO 01/49234 discloses a patient support device which includes a motorized lifting drive. IR barriers are provided on the patient support device, with the function of blocking or releasing a motorized movement. Furthermore, IR sensor means are provided to detect an impending collision of the patient support device with people or objects so that a motorized movement can be blocked in good time.
US 2004/0094077 likewise discloses a patient support device which includes a motorized lifting drive. In order to be able to stop a motorized downward movement of the patient support device in good time, the patient support device has buttons on the base, the actuation of which stops the drive for the downward movement.
The invention addresses the problem of providing a lifting unit that guarantees protection against people and equipment being endangered when the lifting unit is shortened. The invention further addresses the problem of providing a patient support device having a patient couch for an item of equipment for diagnosis and/or therapy and also an item of equipment for diagnosis and/or therapy comprising such a patient support device, which item of equipment guarantees protection against people and equipment being endangered when the lifting unit is lowered.
The invention solves these problems by a lifting unit having the features of claim 1 or by a patient support device having the features of claim 9 or by an item of equipment for diagnosis and/or therapy having the features of claim 11.
A basic concept of the invention consists in providing a lifting unit for an item of equipment for diagnosis and/or therapy , comprising a base plate, a motorized drive, a lifting drive that can be driven by said drive and which is mounted in the base plate, and which can carry out a lifting movement and a movement in the opposite direction, a triggering means being provided which is activated when the force exerted by the lifting drive on the base plate falls below a certain minimum value, the stopping of the movement being triggered in response to the triggering means being activated.
If the lifting drive collides with an obstacle when the patient support device and/or item of equipment for diagnosis and/or therapy is shortened or lowered, this obviously leads to the force exerted thereby on the base plate being reduced. Thus, the stopping of movement triggered by a reduction in the force exerted protects the person or device about to be collided with since in fact the collision is prevented by stopping the movement. Here the maximum collision force obviously depends on the minimum value for the force exerted to activate the triggering means, combined with the total weight borne by the lifting drive. It is obtained by subtracting the total weight from said minimum value.
Further basic concepts underlying the invention consist in providing a patient support device comprising the aforementioned lifting unit and also an item of equipment for diagnosis and/or therapy comprising a patient support device comprising the lifting unit described in the aforementioned.
Further variants and advantages of the invention are defined in the dependent claims and in the description that follows of embodiments with reference to the
Drawings, in which:
FIG 1 shows a schematic diagram of an item of equipment for diagnosis and/or
therapy comprising a patient support device,
FIG 2 shows a schematic diagram of a scissor structure and spindle drive of a
patient support device,
FIG 3 shows a schematic diagram of the ball and socket bearing of the spindle
drive,
FIG 4 shows a schematic diagram of the lifting unit with triggering means in the
form of a switch,
FIG 5 shows a schematic diagram of the lifting unit with triggering means in the
form of an electric contact,
FIG 6 shows a schematic diagram of the lifting unit with triggering means in the
form of a force or pressure transducer and
FIG 7 shows a schematic diagram of the lifting unit with triggering means in the
form of a light barrier.
FIG 1 shows a diagram of an item of equipment for diagnosis and/or therapy (DT device) 3 comprising a patient support device 1. The DT device 3 includes a C-arm 31, which supports an x-ray source 33 and an x-ray detector 34. It can be used, for example, to generate x-ray images in cases of low energy x-ray radiation, or for therapeutic irradiation in cases of higher energy x-ray radiation. The C-arm 31 is housed in a C-arm stand 32. This can be a free-standing structure installed in the room or a structure that is fitted into a wall or ceiling of the room. The C-arm 31 allows the positioning of the x-ray source 33 and of the x-ray detector 34 in such a way that a patient positioned with the aid of the patient support device 1 can be detected by the x-ray beam.
The patient support device 1 includes a couch 11 on which a patient can lie. The couch 11 can be moved in a horizontal direction, which is intended to be indicated by a horizontal two-headed arrow. For this purpose it is mounted onto a
foot 12 with a floating mounting. Furthermore, the height of the couch can be adjusted. For this purpose, the foot 12 includes a lifting device, which is not shown in greater detail in FIG 1. The height adjustment is indicated by a vertical two-headed arrow.
FIG 2 shows in schematic form components of the lifting device of the patient support device 1. The lifting device comprises a base plate 23, which is arranged in or integrated in the foot 12, on which base plate a double-scissor mechanism 13, that is, a structure consisting of two individual scissor mechanisms arranged one on top of the other, is mounted. The double-scissor mechanism 13 is vertically oriented in the sense that it is shortened or lengthened in a vertical direction when actuated. The shortening or lengthening of the double-scissor mechanism 13 provides height adjustment of the lifting plate 22 that is mounted thereon. Connected to the lifting plate 22 is the couch 11, such that the double-scissor mechanism 13 provides height adjustment of the couch 11 and thus of a patient lying thereon.
The double-scissor mechanism 13 is mounted in a solid bearing 21 on the base plate 23. On the opposite side it is mounted in the base plate with a non-locating bearing 16, which includes, for example, a sliding bearing 15. The combination of the solid bearing 21 with the non-locating bearing 16 makes it possible to actuate the double-scissor mechanism 13. In order to be moveable against the lifting plate 22, said plate is mounted on the double-scissor mechanism 13 by means of a non-locating bearing 17, which includes, for example, a sliding bearing 14 on the lifting plate 22. Above the solid bearing 21, the double-scissor mechanism 13 can be connected to the lifting plate 22 by a further solid bearing which is not shown in further detail in the FIG.
The actuation of the double-scissor mechanism 13 is achieved by means of a spindle drive. The spindle drive includes a spindle nut 18 connected to the double scissor mechanism 13 and also a spindle 19. By rotating the spindle 19 or
the spindle nut 18, the height of the spindle nut 18 is adjusted and thus the length of the double-scissor mechanism 13 is adjusted. The rotation of the spindle 19 or of the spindle nut 18 is achieved by a drive 20, which is connected to the spindle
19 in such a way that it is able to rotate said spindle. The drive is typically an
electric motor, but it could also be actuated hydraulically, pneumatically or
manually or be foot-operated.
FIG 3 shows details of the spindle drive in an embodiment that comprises a ball joint. It is possible to see the double-scissor mechanism 13 and the spindle nut 18, the connection point between the two not being shown. The spindle 19 or the spindle nut 18 is rigidly connected to the drive 20 such that the drive 20 can rotate the spindle 19 or the spindle nut 18. The structural unit formed by the drive
20 and the spindle 19 is mounted in the base plate 23 by means of a ball joint.
For this reason, the base plate 23 has a bearing cup 27, which, in the
embodiment shown, includes an elbow section having an angle of about 90°. The
drive 20 and spindle 19 are mounted using a spherical head 26 and bearing cup
27. According to requirements, the spherical head 26 and the bearing cup 27
can consist of appropriate material, be hardened or have bearing cups or bearing
surfaces that have the effect of reducing friction and wear. Such bearing surfaces
are not shown in greater detail in FIG 3.
If a torque is exerted on the double-scissor mechanism 13, for example as the result of an eccentric load on the couch 11 being exerted by a patient lying thereon or because of the eccentrically disposed drive 20, a torque is exerted on the couch 11 and via this onto the spindle drive, which torque can lead to errors in alignment of the spindle drive. The ball joint allows rotation of the spindle drive in such a way that said drive can yield to the torque and thus compensate for said errors in alignment. In this arrangement, the ball joint or the spindle drive can be configured in such a way that the spherical head 26 remains in the ball cup 27 even when the spindle drive is completely disengaged; it is also possible,
however, to have a configuration which allows limited lifting of the spindle drive and thus a limited lifting of the spherical head 26 out of the ball cup 27.
In the embodiment shown, the drive 20 is configured eccentrically with respect to the axis of rotation of the spindle 19. Thus it is also configured eccentrically with respect to the ball joint and thus, as a result of its weight, generates a torque of the spindle drive, this being in fact anti-clockwise in the figure. In order to counteract this torque, the drive 20 is mounted on sprung or elastic bearing elements, on rubber cushions 28 in fact. Instead of rubber cushions, other elastic bearing elements could also be used, for example, on the basis of steel spring elements. The rubber cushions 28 cause the bearing to be moveable by allowing movements of the drive around the ball joint to a slight extent. On the other hand, the rubber cushions 28 have the effect that the drive has self-supporting bearings from the start so that it does not exert any torque on the spindle drive. In other words, the rubber cushions 28 are dimensioned such that the drive 20 remains stable in the position shown. For this purpose, the rubber cushions 28 are likewise not arranged symmetrically round the ball joint but eccentrically such that the eccentric part of the bulk of the drive 20 is given greater support.
The moveable bearings for the drive 20 have to be restricted insofar as the drive 20 exerts a rotational force on the spindle 19. For its part, the drive therefore has to be protected against rotation despite the fact that the bearings are moveable. This is achieved by a lug 25 which is firmly attached to the drive 20 and engages into an anti-twist device 24. The anti-twist device 24 is designed in such a way that although the drive 20 is prevented from rotating round the spindle 19, it can rotate round the ball joint as a result of an eccentric load being exerted on the couch 11 and thus can respond to a change in the alignment of the spindle drive. In this way, the bearings for the drive 20 and the spindle 19 ensure that errors in alignment between the spindle 19 and spindle nut 18 can be compensated for by the eccentric load on the couch 11.
FIG 4 shows a schematic diagram of the lifting unit with triggering means in the form of a switch. The lifting unit is essentially similar to that described in the aforementioned. Instead of the bearing on rubber cushions 28, a connection to the base plate is provided by position-securing elements 102. These could be configured as threaded rods for example. The position-securing elements 102 have the effect that the lifting unit is fixed in a horizontal direction with respect to the base plate, whilst it is moveable to a slight extent in a vertical direction. Vertical mobility is indicated in the FIG by a vertical two-headed arrow to the right of the lifting unit. As soon as the freedom of motion of the position-securing elements 102 has been exhausted, the lifting unit is fixed in a vertical direction.
The lifting unit can be shortened or lengthened in a vertical direction in order to raise or lower a couch or load that is supported thereby. When lowered, the load or couch may collide with an obstacle that prevents further lowering. In this case, the obstacle acts as a brake on the load or couch whilst the lifting unit is further shortened by the motorized drive without the above being taken into account. The further shortening of the lifting unit leads to it resting on the base plate with a decreasing weight. As soon as the weight has become sufficiently low, the lifting unit is raised and lifted off the base plate. The position-securing elements 102, which allow vertical movements of the lifting unit, do nothing to prevent this. In a further embodiment like that described in the aforementioned but not shown in greater detail in FIG 4 and in which the lifting unit is mounted on the base plate in a ball joint, this means that the spherical head of the ball joint is lifted out of the ball cup.
As soon as the lifting unit is raised as described above, its lug touches the triggering means configured as a switch 25. In the process, the switch 25 is actuated and thus the triggering means is activated. As a result of the actuation of the switch 25, the drive of the lifting unit is switched off, so that a further shortening of the lifting unit or a further lowering of the couch or load is prevented. As a result, this obviously prevents a further increasing reduction in

the load on the lifting unit and thus, as a consequence thereof, prevents there being an increasing load on the position-securing elements 102, which form the means of securing the lifting unit in the base plate. Furthermore, a further increase in the load on the obstacle that was collided with, for example a person or a device, is prevented.
FIG 5 shows a schematic diagram of the lifting unit with triggering means in the form of an electric contact. Here the lifting unit is mounted on bearings 105 in such a way that is vertically moveable at least to a limited extent. The bearings 105 can be configured as rubber cushions as they are further above, or as spring elements or position-securing elements as described in the aforementioned.
An electric contact 108 is provided under the spindle drive between the lifting unit and the base plate. Said contact is created by reciprocal contact between a contact means 107 located on the base plate and of a contact means 109 located on the lifting unit. The contact means 107, 109 can be configured as metallic contact elements. In particular, they can be configured as integrated bearings and contact means.
When the lifting unit is raised from the base plate, as explained in the above description of FIG 4, the electric contact is interrupted. This interruption represents the activation of the triggering means and causes the drive of the lifting unit to be turned off.
FIG 6 shows a schematic diagram of the lifting unit with triggering means in the form of a force or pressure transducer. Here the lifting unit is again mounted on bearings 105. A force or pressure transducer 110 is arranged under the spindle drive, said transducer measuring the supporting force exerted by the lifting unit on the base plate. If the force measured falls below a predetermined amount, the force or pressure transducer 110 is activated as a triggering means and causes the drive for the lifting unit to be turned off.
FIG 7 shows a schematic diagram of the lifting unit with triggering means in the form of a light barrier 120. The light barrier 120 includes a lighting means 121 and a light sensor 122. Light generated by the lighting means 121 can reach the light sensor 122 along the path shown in the FIG by a dotted line. As long as the lifting unit is on the base plate, this path is interrupted by an extension 125 of the lifting unit as shown in the FIG. If the lifting unit is raised, as described in the aforementioned, then the extension 125 is lifted out of the light barrier 120. As a result, the extension is activated as a triggering means and causes the lifting unit drive to be turned off.
In a further advantageous embodiment, after the activation of the respective triggering means, the lifting unit can be controlled in such a way that not only is further shortening prevented but that it is additionally lengthened again by a predetermined amount; in other words, not only is the lowering of the load or couch prevented but said couch is lifted again by a predetermined amount. As a result, not only is it possible to prevent a further increase in the load exerted as the unit is shortened but, furthermore, the load is immediately reduced again. This in particular is advantageous if there has been a collision with a sensitive device or even a person.
The invention can be summarized as follows: the invention relates to a lifting unit for a patient support device 1, including a base plate 23, a motorized drive 20, a lifting drive that can be driven by said drive and which is mounted in the base plate 23, said lifting drive being able to carry out a lifting movement and a movement in the opposite direction, a triggering means being provided which is activated when the pressure exerted by the lifting drive on the base plate 23 falls below a pre-determined minimum value. The movement of the lifting drive is stopped in response to the activation of the triggering means. If the patient support device 1 collides with an obstacle as it is lowered, the pressure exerted
by the lifting drive on the base plate is reduced. This event is detected by the triggering means and the movement of the patient support device is stopped.

We Claim:
1. A lifting unit for a diagnosis device, a treatment device or a diagnosis and treatment device, the lifting unit comprising: a base plate, a motorized drive,
a lifting drive operable to be driven by the motorized drive and provide a lifting movement in a direction opposite the base plate, the lifting drive being mounted on the base plate, and
a triggering device configured as a power- or pressure transducer is arranged between the lifting drive and the base plate such that the triggering device is operable to detect when the lifting drive raises up from the base plate, the triggering device being configured to be activated when an electric contact interruption is detected as a result of the lifting drive raising up from the base plate,
wherein the movement of the lifting drive is triggered to stop in response to the activation of the triggering device, and
the electric contact is created by reciprocal contact between a first contact device located on the base plate and a second contact device located on the lifting device.
2 A lifting unit as claimed in claim 1, wherein the movement is stopped by
interrupting the power connection between the drive(20) and the lifting drive, in particular by breaking a connection that is provided for this purpose.
3. A lifting unit as claimed in claim 1, wherein the movement of the lifting drive is stopped by switching off the drive.
4. A lifting unit as claimed in claim 1, wherein the lifting drive is coupled with a double-scissor mechanism that provides height of a lifting plate connected to a patient support.
5. A lifting unit as claimed in claim 1, wherein the motorized drive is an electric
motor, hydraulically-actuated drive, pneumatically-actuated device, or foot-
operated device.
6. A lifting unit as claimed in claim 1, comprising a power connection between the motorized drive and the lifting unit, the movement of the lifting drive being stopped when the power connection is interrupted.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=+NleTcaGglFrYn4l4WCA4w==&loc=+mN2fYxnTC4l0fUd8W4CAA==

« Previous Patent

Next Patent »

Patent Number

268849

Indian Patent Application Number

7341/DELNP/2007

PG Journal Number

39/2015

Publication Date

25-Sep-2015

Grant Date

18-Sep-2015

Date of Filing

24-Sep-2007

Name of Patentee

SIEMENS AKTIENGESELLSCHAFT

Applicant Address

WITTELSBACHERPLATZ 2,80333 MUNCHEN,GERMANY.

Inventors:

#	Inventor's Name	Inventor's Address
1	DIPPL; THOMAS	REICHWEINSTR. 19A,92690 PRESSATH,GERMANY.
2	HRUSCHKA; KLAUS	WILHELM-BAUER-STRABE 1, 92681 ERBENDORF, GERMANY.
3	RING; MARIO	HINTER DEM KLOSTER 29, 95478 KEMNATH, GERMANY.
4	RUPPRECHT; JOSEF	SCHWEISSOHSTR. 60, 92681 ERBENDORF, GERMANY.

PCT International Classification Number

A61G 13/00

PCT International Application Number

PCT/EP2006/061236

PCT International Filing date

2006-03-31

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2005 015 795.5	2005-04-06	Germany