Abstract:
The invention relates to an articulated arm system ( 20 ) for attaching different medical imaging devices ( 11 ) to support structures ( 14 ) in an articulated manner. The articulated arm comprises at least one parallelogram device ( 15   a,    15   b ) including a counterbalancing mechanism for holding the articulated arm and the device ( 11 ) supported by it in place when the device is located in the desired imaging position. The system further comprises braking and/or locking means ( 2: 22 ) which act on at least one strut bar ( 6, 7 ) of the said at least one parallelogram device ( 15   a   , 15   b ) and/or on the at least one additional strut bar ( 1 ) in order to prevent mutual linear movement of the strut bars ( 6, 7 ) of the parallelogram device, and which braking and/or locking means comprise actuators ( 3-5; 23; 24 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is the U.S. national stage application of International Application PCT/FI00/01045, filed Nov. 30, 2000, which international application was published on as International Publication WO 01/40700. The International Application claims priority of Finnish Patent Application 19992570, filed Dec. 1, 1999. 
    
    
     The present invention relates to an articulated arm system for attaching different medical imaging devices to support structures in an articulated manner, the articulated arm comprising at least one parallelogram device with at least two mutually parallel strut bars; and a counterbalancing mechanism for holding the articulated arm and the device supported by it in place when the device is located in the desired imaging position. The counterbalancing mechanism preferably comprises at least one additional strut bar and counterbalancing means. 
     There are already articulated arm systems of the type mentioned in the introduction on the market, one problem with which is, however, the loosening of the springs and articulations with time, due to which the device will not, for example, remain in place during imaging, whereby the imaging result will obviously deteriorate. Accordingly, one important object of the present invention is to provide an improved articulated arm system for attaching different medical imaging devices, for example, devices for imaging the head area, such as intraoral and panoramic imaging devices, to support structures in an articulated manner, by means of which articulated arm system is ensured, through relatively simple measures, that the device will stay in place during imaging. 
     BRIEF SUMMARY OF THE INVENTION 
     In order to achieve the objects of the invention, the articulated arm system according to the first aspect of the invention for attaching different medical imaging devices to support structures in an articulated manner, the articulated arm comprising at least one parallelogram device with at least two mutually parallel strut bars; and a counterbalancing mechanism for holding the articulated arm and the device supported by it in place when the device is located in the desired imaging position, is characterised in that the system further comprises braking and/or locking means which act on at least one strut bar of the said at least one parallelogram device and/or on the said at least one additional strut bar in order to prevent mutual linear movement of the strut bars of the parallelogram device, and which braking and/or locking means comprise actuators. 
     An articulated arm system relating to a second aspect of the invention for attaching different medical imaging devices to support structures in an articulated manner, the articulated arm comprising at least one parallelogram device with at least two mutually parallel strut bars; and a counterbalancing mechanism for holding the articulated arm and the device supported by it in place when the device is located in the desired imaging position, is characterised in that the counterbalancing mechanism is comprised of an air spring arranged between one strut bar and an articulated part, which spring can be locked into the desired position, thus preventing the mutual linear movement of the strut bars of the parallelogram device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention is described in greater detail in the following, with reference to the appended drawings, in which: 
     FIG. 1 shows a diagrammatic side view of one embodiment of the articulated arm system relating to the invention, 
     FIG. 2 shows diagrammatically an alternative embodiment of the braking and/or locking means used in the articulated arm system relating to the invention, 
     FIG. 3 shows a section along line III—III of the embodiment shown in FIG. 2, 
     FIGS. 4-5 show diagrammatically certain alternative embodiments of the articulated arm system relating to the invention, and 
     FIGS. 6 and 7 show further alternative embodiments of the articulated arm system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to FIG. 1, the articulated arm system  20  comprises a first parallelogram device  15   a , a spacing piece  10  and a second parallelogram device  15   b . The first parallelogram device  15   a  is attached through a connecting piece  18  and articulation pieces  13  and  12  to a support structure  14 , for example, a wall or a pillar. At the free end of the second parallelogram device  15   b  is attached the desired imaging device  11 , for example, an intraoral imaging device, through a connecting piece  19 . Both parallelogram devices  15   a ,  15   b  comprise parallel strut bars  6 ,  7  which are connected to the spacing piece  10  and the connecting pieces  18  and  19  by means of articulations  8   a  and  8   b . The mutual distance between the pivots  8   a  in the connecting piece  18  of the parallelogram device  15   a  is equal to the mutual distance between the pivots  8   b  in the spacing piece  10 , and correspondingly, the mutual distance between the pivots  8   a  in the parallelogram device  15   b  is equal to the mutual distance between the pivots  8   b . This means that when the articulated arm is used for adjusting the device  11  into the correct position, the spacing piece  10  will remain in essentially the same position throughout; in the case shown, the spacing piece  10  is essentially horizontal throughout. 
     In the embodiment shown in FIG. 1, both parallelogram devices have a counterbalancing mechanism with an additional strut bar  1 , around which there is a counterbalancing spring  16  for holding the articulated arm and the device supported by it in place. The additional strut bar  1  is preferably round and, in the embodiment shown, connected with bar  9  in parallelogram device  15   a  to the connecting piece  18  and in parallelogram device  15   b  with the spacing piece  10 . To prevent unintentional movement of the articulated arm, in the solution relating to the invention, braking and/or locking means have been mounted around the additional strut bar  1 . In the embodiment shown, these means comprise a locking piece  2  which includes a sleeve part surrounding the additional strut bar  1 . This piece  2  is connected to a lever arm  3  which is loaded by force F to press the sleeve against the additional strut bar  1 . In the embodiment shown, the force F is generated by means of the spring  4 . In this solution, the locking is normally always on, and in order to adjust the device into the desired position, at the end of the lever arm  3  are arranged actuators  5 , for example, a solenoid, which is made to pull by pressing the switch button  17  on the connecting piece  19 , whereby the lever arm  3  presses against the force of the spring  4 , allowing easy movement of the additional strut bar  1  inside the sleeve part of the locking piece  2 . The use of this locking piece  2  can also be implemented vice versa, whereby the lever arm  3  is normally turned in such a way that the additional strut bar  1  is able to move inside the sleeve part, and when the articulated arm is to be locked, for example, a solenoid  5  is used for turning the lever arm  3  in such a way that the sleeve part presses against the additional strut bar  1 . Instead of a spring  4  and a solenoid  5 , the actuator of the lever arm  3  may be, for example, a motor equipped with a self-locking worm gear (see FIG.  6 ), or even manual operation (see FIG.  7 ). 
     FIGS. 2 and 3 show an alternative friction-operated locking and/or braking device acting on the additional strut bar  1 , in which device a conical locking piece  22  is used instead of a sleeve, the locking piece being provided with at least one axial gap which allows circumferential movement of the locking piece in such a way that the locking piece is pressed by means of the opposite conical piece  23  loaded by the counterbalancing spring  16  against the surface of the additional strut bar  1 . Each gap may extend either over only a part of the axial length of the locking piece or over its entire length, which means that the conical piece may also be comprised of two or more separate parts. To the conical piece  23  are attached lever arms  24  by means of joint pins  25 , the lever arms forming a pliers-type means on either side of the additional strut bar  1 . By pressing the lever arms  24  which are against each other at each time towards each other, the conical piece  23  is made to move away from the attachment with the locking piece  22 , which means that the additional strut bar  1  can move easily with respect to the locking piece  22 . When the compression on the lever arms  24  ceases, the spring  16  loads the conical piece  23  back against the locking piece  22 . The locking piece  22  may also be made of an elastic material, for example, rubber, and its shape may also be other than conical. The elastic locking piece may extend uniformly around the additional strut bar  1 , whereby elasticity will make possible pressing it against the additional strut bar. 
     FIG. 4 shows another alternative embodiment in which the counterbalancing mechanism of the parallelogram device is comprised of the lock-up air spring  30  arranged each time between the connecting piece  18  or  19  and the strut bar  6 . In this case, the additional strut bar  1  and the counterbalancing spring  16  connected to it can be omitted. Locking the air spring prevents the mutual linear movement of the strut bars  6  and  7  of the parallelogram device  15   a  and  15   b , respectively. The air spring may also be arranged in only one parallelogram device, while the other is equipped with, for example, the counterbalancing mechanism shown in FIG.  1 . 
     FIG. 5 shows yet another alternative embodiment which differs from the embodiment shown in FIG. 1 in that between the strut bars  6  and  7  of the parallelogram device is arranged a transverse lever  31  by means of which the strut bars  6 ,  7  can be interlocked, in which case the means  2  to  5  are omitted. The transverse lever may be, for example, a lock-up telescopic lever which allows mutual linear movement of the strut bars when the lever is not locked, for example, a lock-up air spring. As a lever may also be used a rigid lever which is attached at least at one end to the corresponding strut bar  6  or  7  in such a way that the end of the lever can move with respect to the strut bar when not locked, allowing mutual linear movement of the strut bars  6 ,  7 , and when locked, will prevent the mutual linear movement. This attachment of the transverse lever to the strut bar may be realised, for example, by providing the end of the transverse lever with a pin which moves in a guide groove or loop formed in the strut bar. 
     The embodiments described above are merely examples of certain preferred implementations of the invention and are not intended to limit the scope of protection of the invention defined in the appended claims.