Medical apparatus comprising a movable patent table having a common control member for operating longitudinal drive and locking mechanisms

Medical apparatus includes a patient table (7) with a table support (9) and a table top (11) which is movable at least in its longitudinal direction relative to the table support, there being provided a first drive mechanism (21) to assist said movement, if desired; the table top can be locked relative to the table support by means of a locking mechanism (23). The apparatus comprises a common control member (43) for moving the table top (11) in the longitudinal direction and for operating the first drive mechanism (21) and the locking mechanism (23). The control member comprises a link rod (57) which is movable in its longitudinal direction and which cooperates with a switch (67) for operating the locking mechanism, and also comprises a control element (71) which is movable transversely of the longitudinal direction of the link rod and which cooperates with a sensor (73) which supplies an output signal for control of the drive mechanism. The link rod (57) and the control element (71) are movable by means of a common control knob (59) whereby the table top (11) can be moved also without assistance from the first drive mechanism (21). Consequently, control of the movements of the table top (11) is very simple and orderly.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a medical apparatus, including a patient table 
with a table support and a table top which is movable at least in its 
longitudinal direction relative to the table support, there being provided 
a first drive mechanism for assisting this movement, if desired, it being 
possible to lock said table top relative to the table support by means of 
a locking mechanism. 
2. Description of the Prior Art 
An apparatus of this kind is known from EP-A-0 506 172. The known apparatus 
is provided with a motor for moving the table top in the longitudinal 
direction, the table top being displaced on rollers which can be blocked 
by way of the locking device. Separate control members are provided for 
control of the motor and the locking device. The control members are 
accommodated on a console which also comprises a large number of other 
control members for other functions of the apparatus. Because of this 
large number of control members, the console is rather cluttered and 
operation requires close attention. 
SUMMARY OF THE INVENTION 
It is an object of the invention to improve an apparatus of the kind set 
forth so that control is simplified. To achieve this, the apparatus in 
accordance with the invention is characterized in that it comprises a 
common control member for moving the table top in the longitudinal 
direction and for controlling the first drive mechanism and the locking 
mechanism, which control member comprises a link rod which is movable in 
its longitudinal direction and which cooperates with a switch in order to 
operate the control mechanism, and also comprises a control element which 
is movable transversely of the longitudinal direction of the link rod and 
which cooperates with a sensor which supplies an output signal for 
operating the drive mechanism, the link rod and the control element being 
movable by means of a common control knob whereby the table top can be 
moved also without assistance from the first drive mechanism. Thanks to 
these improvements, full control of the table top can be exercised with 
one hand, so that the person operating the apparatus can pay more 
attention to other functions of the apparatus. 
An embodiment of the apparatus in accordance with the invention which can 
be realized in a technically simple manner is characterized in that the 
link rod is journalled so as to be movable in its longitudinal direction 
in a bearing sleeve which supports the control element and which can be 
tilted about a shaft extending transversely of its longitudinal direction, 
the control knob being attached to a first end of the link rod which is 
situated near a first end of the bearing sleeve, the arrangement being 
such that by pressing the control knob the link rod can be moved in its 
longitudinal direction from a first position to a second position, the 
bearing sleeve itself being tiltable about said shaft from a neutral 
position into two opposite directions under the influence of a lateral 
force exerted on the control knob, the force exerted on the control knob 
being transferred to the bearing sleeve via the link rod. In order to 
ensure that the control member always reaches a predetermined position 
automatically when the control knob is released, a preferred embodiment of 
the apparatus in accordance with the invention is characterized in that 
there are provided first resilient means which exert a force on the link 
rod which drives the link rod to its first position, there also being 
provided second resilient means which exert a force on the bearing sleeve 
which drives the bearing sleeve to its neutral position. 
There are various possibilities to connect the control element to the 
bearing sleeve. A very simple solution is characterized in that the 
control element is situated near a second end of the bearing sleeve, the 
sensor which is rigidly mounted near said second end being operative to 
supply an output signal which is dependent on a lateral displacement of 
the control element. The control element is preferably formed by a pin 
which laterally projects from the bearing sleeve and which is made of a 
magnetically conductive material, the sensor being a magnetic sensor. 
Magnetic sensors are rugged and reliable. 
A further preferred embodiment of the device in accordance with the 
invention is characterized in that there is provided a second drive 
mechanism which is operative to tilt the table top relative to the table 
support about a horizontal shaft which extends transversely of the 
longitudinal direction of the table top, there also being provided 
compensation means which are operative to exert a force on the table top 
which is directed upwards in the longitudinal direction of the table top 
and is dependent on the total mass of the table top plus a load present 
thereon and on the angle wherethrough the table top has been tilted 
relative to the horizontal position, said force being substantially equal 
to the force exerted downwards by gravity in the longitudinal direction of 
the table top. As a result of the presence of the compensation means, the 
person operating the apparatus experiences hardly any difference between 
the horizontal position and an oblique position of the table top.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The apparatus shown in FIG. 1 is an X-ray examination apparatus which 
comprises a support 1, for example a C-arm, whereto an X-ray source 3 and 
an X-ray detector 5, for example an X-ray image intensifier tube, are 
connected. The support 1 is secured to the ceiling or to the floor of an 
examination space so as to be movable relative to a patient table 7. The 
patient table 7 comprises a table support 9 and a table top 11 which is 
connected to the table support. Between the table top 11 and the table 
support 9 there are provided first rollers 13 which enable movement of the 
table top in the longitudinal direction (in conformity with the double 
arrow 15). Preferably, there are also provided second rollers 17 which 
enable movement of the table top parallel to its plane perpendicular to 
the direction denoted by the arrow 15 (i.e. perpendicularly to the plane 
of drawing). For the movement of the table top 11 in the direction of the 
arrow 15 there is provided a first drive mechanism which comprises, for 
example a motor 21 (denoted by a dashed line) which is accommodated in a 
motor housing 19. The motor 21 drives one or more of the first rollers 13 
via a transmission which is not shown in FIG. 1 (for example, a chain or a 
drive belt). The table top 11 can be locked in any desired position by 
means of a locking mechanism which comprises, for example brake blocks 23 
which can be pressed against the first rollers 13 by way of an 
electromagnetic drive (not shown). The second rollers 17 may also be 
provided with brake blocks (not shown). Instead of a drive belt or chain, 
the first drive mechanism may also comprise other known transmissions, for 
example a rack and pinion. 
A patient to be examined can be arranged on the table top 11, the patient 
then being irradiated by an X-ray beam which originates from the X-ray 
source 3 and which is incident on the X-ray image intensifier 5 after 
having traversed the patient. Because the table top 11 and the support 1 
are movable, different parts of the patient can be irradiated from 
different directions. For some examinations it is also desirable that the 
patient is in a position other than the horizontal position. To this end 
there is preferably provided a second drive mechanism which will be 
described in brief with reference to FIG. 2. 
FIG. 2 shows diagrammatically the table top 11 with the first rollers 13 
and the motor 21 which forms part of the first drive mechanism and which 
drives one or more of the first rollers via a chain 29. The second drive 
mechanism 31 is a mechanism which is known per se and which comprises a 
motor (not shown) which drives vertical rods 33, for example hydraulically 
or via toothed racks, the first rollers 13 being secured to the upper ends 
of said vertical rods. Consequently, the rods 33 move in the vertical 
direction, together with the first rollers 13, as denoted by the double 
arrows 35. Because the movement of the rods 33 can be separately 
controlled, the table top 11 can thus be tilted about a horizontal shaft 
which extends transversely of the longitudinal direction of the table top, 
so that the plane of the table top can be adjusted so as to enclose an 
arbitrary angle .alpha. relative to the horizontal plane. When a load 37 
(for example, a patient) is positioned on the table top 11, gravity exerts 
a vertically directed force m.multidot.g on the combination formed by the 
table top and the load, in which m is the total mass of the table top plus 
the load and g is the acceleration of the force of gravity. When the table 
top 11 encloses an angle .alpha. relative to the horizontal plane, this 
force has a component F.sub.g which is directed downwards in the 
longitudinal direction of the table top. F.sub.g is then equal to 
m.multidot.g.multidot.sin(.alpha.). The first drive device 21 is 
preferably controlled so that this drive device exerts a force on the 
table top 11, which is directed upwards in the longitudinal direction of 
the table top and which is substantially equal to the force F.sub.g. To 
this end, the patient table 7 may be provided with an angle detector for 
measuring the angle .alpha., for example as described in US-A-3 822 875 
and with a weighing mechanism for determining the total mass (not shown). 
On the basis of this data a central control unit 39 (see FIG. 1) can 
calculate the drive force to be exerted on the table top 11 by the motor 
21, and supply the motor with an appropriate control signal. Evidently, it 
is also possible to provide a separate drive mechanism for compensation of 
the force F.sub.g, so that the first drive mechanism 21 serves exclusively 
for moving the table top 11 in the longitudinal direction. 
For operation of the apparatus a console 41 is attached to the patient 
table 7 and connected to the control unit 39 which supplies inter alia 
control signals for the first drive mechanism 21 and the locking mechanism 
23. To this end, the console 41 is provided with a number of control 
members, one of which is denoted by the reference numeral 43. The control 
member 43 serves as a common control member for the first drive mechanism 
21 and the locking mechanism 23. The construction of this common control 
member 43 will be described in detail hereinafter with reference to FIG. 
3. 
FIG. 3 shows a front plate 45 of the console 41 in which there is provided 
an opening 47. At the area of the opening 47 a support 49 is secured to 
the upper side of the front plate 45; at its lower side there is provided 
a bearing 51 in which a horizontal shaft 53 is journalled. A bearing 
sleeve 55 which extends vertically through the opening 47 can be tilted 
about the shaft 53. A link rod 57 which also extends vertically through 
the opening 47 is journalled in the bearing sleeve 55 so that it is 
movable in its longitudinal direction. A control knob 59 is mounted on a 
first end of the link rod 57 (the upper end in FIG. 3). Between the link 
rod 57 and the bearing sleeve 55 there is provided a resilient element in 
the form of a helical spring 61 which exerts a force on the link rod so 
that the link rod is forced in a first position. The link rod 57 can be 
moved downwards, against the force of the spring 61, by exerting a 
pressure on the control knob 59, until it occupies a second position which 
is lower than the first position. In the embodiment shown, the second end 
(the lower one in FIG. 3) of the link rod 57 is provided with a disc-like 
control element 63 which can cooperate with a pushbutton 65 of a switch 67 
which is operative to make the central control unit 39 supply a signal 
which switches the locking device 23 on or off. The locking device 23 can 
then be switched off, for example by depression of the control knob 59. 
Evidently, other types of switch can also be used, for example a switch 
which is responsive to a magnetic field in combination with a control 
element 63 in the form of a permanent magnet. 
When a lateral force is exerted on the control knob 59 (in one of the two 
directions perpendicular to the plane of drawing), this force is 
transferred to the bearing sleeve 55 via the link rod 57, so that the 
sleeve is tilted about the shaft 53. If desired, the control knob 59 may 
also be directly connected to the bearing sleeve 55. Near a first end (the 
upper end in FIG. 3), situated in the vicinity of the first end of the 
link rod 57, the bearing sleeve 55 is mounted in a resilient ring 69 which 
exerts a force on the bearing sleeve which drives the bearing sleeve to a 
neutral position in which it extends substantially vertically. This force 
must be overcome in order to tilt the bearing sleeve 55. Near its second 
end (the lower end in FIG. 3) the bearing sleeve 55 is provided with a 
control element in the form of a pin 71 which laterally projects from the 
bearing sleeve and which cooperates with a sensor 73 which is operative to 
detect a displacement of the pin. The pin 71 is preferably made of a 
magnetically conductive material. The sensor 73 may be a magnet sensor as 
will be described with reference to FIG. 4. Other combinations of control 
elements and sensors, of course, are also feasible. For example, the 
control element 71 may comprise a light source and the sensor 73 may be a 
light-sensitive detector which produces a signal which is dependent on the 
location of the light source. The control element 71 may also be connected 
directly to the link rod 57, if desired, so that the bearing sleeve may be 
shorter or even be completely dispensed with. Regardless of the 
construction, the sensor 73 produces an output signal which is a measure 
of the lateral deflection of the bearing sleeve 55, and hence of the 
magnitude of the lateral force exerted on the control knob 59. This output 
signal is applied to the central control unit 39 which responds by 
applying an appropriate control signal to the first drive mechanism 21. 
FIGS. 4A and 4B show some details of the above preferred embodiment of the 
combination formed by the control element 71 and the sensor 73. In the 
present embodiment, the control element 71 is formed by a pin of a 
magnetically conductive material, for example iron. The sensor 73 is a 
magnetic sensor, i.e. a sensor which detects disturbances of a magnetic 
field in its vicinity. Such disturbances are dependent on the position of 
the pin 71. The sensor comprises an approximately cylindrical housing, on 
one of the end faces of which there are provided magnetoresistive 
resistors 75. The housing accommodates a permanent magnet and an 
electronic circuit (not shown). When the pin 71 occupies a symmetrical 
position relative to the magnetoresistive resistors, as shown in FIG. 4, 
the sensor 73 produces an output voltage which equals zero. When the 
position of the pin 71 deviates from this neutral position in the one or 
the other direction, the sensor 73 produces a positive or a negative 
output voltage, respectively. A suitable sensor is, for example the 
Siemens sensor type number 
The table top 11 can be moved in the direction of the arrow 15 by means of 
the common control member 43. This can be realized by exerting a force by 
hand, via the control knob 59, on the table top 11 or by making the drive 
mechanism 21, controlled via the common control member 43, assist the 
movement. This drive mechanism is then controlled by signals which are 
supplied by the central control unit 39 in response to the output signal 
of the sensor 73. If the table top is not in the horizontal position, the 
central control unit 39 also ensures that the downwards directed force 
F.sub.g in the longitudinal direction of the table top is compensated for 
as described with reference to FIG. 2. The table top 11 can also be 
displaced perpendicularly to the plane of drawing of FIG. 1 by means of 
the common control member 43. Generally speaking, no assistance from a 
drive mechanism is required for the latter displacement. Finally, the 
table top 11 can be locked in any desired position by the common control 
member by releasing the control knob 59. Via the common control member 43, 
the movements of the table top can thus be controlled with one hand.