Control unit of a medical apparatus

Abstract: The invention relates to a control unit of a medical apparatus with a front panel (1) with setting knobs (5). In order to transfer a turning setting movement through the front panel (1), a feed-through sleeve (6) is rotatably arranged in the front panel (1) and a knob core (10) is movably arranged in the feed-through sleeve (6). On the control side of the front panel (1), the feed-through sleeve (6) and the knob core (10) are enclosed by a handling element (16), which through application of pressure can move the knob core (10) in the feed-through sleeve (6), whereby the knob core (10) on the back side of the front panel (1) moves a springing locking washer (11) from a locking position to an unlocked position so that a turning of the handling element (16) also will move the feed-through sleeve (6). In order to improve the sealing at the feed-through, the front panel (1) is provided with a protection plate (4) which is beaded (21) outwards at the feed-through sleeve (6), whereby the handling element (16) tightly encloses the beaded (21) part.

Description: The invention relates to a control unit of a medical apparatus comprising a front panel in which at least one setting knob and/or a switching knob is located, the setting-/switching knob including a knob core, accessible from the front of the front panel, whereby the setting-/switching knob is locked in at least one direction of rotation by a stop when no force is applied to the knob core and the setting-/switching knob is turnable in both directions of rotation when force is applied to the knob core against a springing arrangement. In EP-A-0 271 982 a setting knob which is placed in a panel and normally locked in both rotational directions is disclosed. To change a setting the knob must be pushed against a spring, thereby disengaging a pinion. After the change in the setting, when the knob is released, the spring will force the pinion back to an engaging position, preventing further rotational movement. The number of teeth on the pinion determines the number of possible settings. Another control unit is known through a service manual of Servo Ventilator 900B, Siemens-Elema AB, publication No. S1080 5,5, October 1980 and comprises a front panel with setting knobs that control potentiometers for setting of a number of different ventilator functions. A knob comprises a turning knob on the front of the front panel, which turning knob is screwed onto a feed-through shaft, which passes through the front panel to the potentiometer. The feed-through shaft is fastened axially in the front panel with a nut on the back side of the front panel and a locking nut on the front. To protect the control unit from the penetration of liquid, the front panel is covered with a thin protection plate of plastic. At the hole through the front panel, the locking nut prevents liquid from penetrating by its pressure against the front panel. The setting knobs of the control unit cannot, however, be fixed at the set positions, which means that a setting can be changed by mistake. There is also a risk that the potentiometer or the turning knobs break, as the force applied to the turning knob is directly transferred to the potentiometer via the feed-through shaft. An object of the invention is to provide a control unit that is easy to set in various positions without risking an accidental change of setting, and constructed in such a way that the potentiometer does not break from too much turning force applied to the setting knob and the front panel in an easy manner effectively seals off liquid, in particular in the area of the setting-/switching knobs. This object is achieved in accordance with the invention in that a feed-through sleeve of the setting-/switching knob is rotatably arranged in the front panel for effecting the setting and/or switching, and in that the knob core is arranged in a movable and springing manner in the feed-through sleeve. Hereby, a setting-/switching knob is obtained which is easy to handle by releasing the catch via the knob core and turning the knob to a desired setting with the feed-through sleeve. The knob can be locked either in both directions or in only one direction to prevent a higher value than the desired to be set, for example. An improvement of the Control unit is obtained in accordance with the invention in that a locking washer with at least one locking hook is fastened to the knob core at the feed-through sleeve and locks the setting-/switching knob against the stop. It is in this connection an advantage if the locking washer in itself is springing and thereby forms the springing arrangement. In connection with this solution of the problem, it is advantageous to have a handling element tightly enclose the feed-through sleeve and the knob core on the front of the front panel. By having the handling element affect the feed-through sleeve by the friction that exists between them, the force that can be transferred from the handling element via the feed-through sleeve to the potentiometer is limited, and, before the force becomes great enough to damage the potentiometer, the handling element will start to glide in relation to the feed-through sleeve. By constructing the handling element with a bulge, preferably in the shape of a collar, the handling of the knob will be simplified as the collar works as a riveting head for the force applied to the knob core. By beading the front panel, or by beading a protection plate of the front panel at the feed-through sleeve and by using a handling element that is elastic and encloses the beaded part, a liquid-proof front panel is obtained for the above mentioned solution. With an exchangeable protection plate it is also possible to quickly and easily adapt the front panel to a different language, to different settings, etc. An embodiment of the invention is described in connection with three figures, whereby fig 1 shows a cross-section of a setting knob in a front panel of a control unit of a medical apparatus, fig 2 shows a locking washer of the setting knob and fig 3 shows a cross section of a feed-through sleeve of the setting knob. A part of a front panel 1 of a control unit is shown in fig 1 together with a setting knob 5. The front panel 1 is made up by a back panel plate 2 and a front panel plate 3, whereby the front panel plate 3 is exchangeable and has a thin plastic plate 4 glued onto it. The setting knob 5 comprises a feed-through sleeve 6, 12, a console 7 and a handling element 16. In the console 7, a potentiometer 8 is located, which is connected to the feed-through sleeve 6. The console 7 is fastened to the back panel plate 2 by means of two screws 9A, 9B thereby holding the potentiometer 8 and the setting knob 5 in place on the front panel 1. As can be seen from fig 3, the feed-through sleeve 6 comprises two recesses, which have left two diametrically opposite branches 14 (only one is visible). A slot 15 of the locking washer 11 (fig 2) fits over these branches 14. The knob core 10 in fig 1 has an annular groove 17 in which the locking washer 11 is to be fixed. In order to obtain a well-defined position for the locking washer 11 relative to the knob core 10, the slot 15 of the locking washer 11 is made narrower than the diameter of the annular groove 17 of the knob core 10 except at a place which corresponds to the well-defined position for the locking washer 11. At this place, the slot 15 of the locking washer 11 is adapted to the annular groove 17. In fig 2, it is shown that the locking washer 11 further comprises two slots 13A, 13B, which are responsible for the springing ability of the locking washer 11 which is necessary in order to make the knob 5 function. Necessary are also the two shoulders 18A, 18B, which, when the locking washer 11 is mounted, are in contact with the surface 19 (fig 3) of the feed-through sleeve 6. When the knob core 10 is pressed, the locking washer 11 will be forced apart at the two slots 13A, 13B and a locking hook 20 on the underside of the locking washer 11 (indicated with a broken line in fig 2) may be moved past the stop 12. In fig 1, the stop is formed as a nib on the back side of the front panel 1. The number of stops 12 depend on the number of settings made available to the setting knob 5. The locking hook 20 may be formed like a tooth to enable locking in both directions or have a slope on one side to be able to glide over the stop 12 in one direction. The handling element 16 is made of an elastic material and encloses the feed-through sleeve 6 and the knob core 10 at the front of the front panel 1. In order to improve the sealing ability of the front panel 1 at the knob 5, the plastic plate 4 is beaded 21 outwards at the feed-through sleeve 6 and the handling element 16 tightly encloses the beaded part. To facilitate the handling of the setting knob 5, the handling element 16 is also provided with a collar 22. 1 front panel 2 back panel plate 3 front panel plate 4 plastic plate 5 setting knob 6 feed-through sleeve 7 console 8 potentiometer 9A, 9B screws 10 knob core 11 locking washer 12 stop 13A, 13B slots 14 branches 15 slot 16 handling element 17 annular groove 18A, 18B shoulders 19 surface 20 locking hook 21 bead 22 collar

Claims: Control unit of a medical apparatus comprising a front panel (1) in which at least one setting knob (5) and/or a switching knob is located, the setting-/switching knob including a knob core (10), accessible from the front of the front panel (1), whereby the setting-/switching knob is locked in at least one direction of rotation by a stop (12) when no force is applied to the knob core and the setting-/switching knob is turnable in both directions of rotation when force is applied to the knob core (10) against a springing arrangement, characterized in that a feed-through sleeve (6) of the setting-/switching knob is rotatably arranged in the front panel (1) for effecting the setting and/or switching, and in that the knob core (10) is arranged in a movable and springing manner in the feed-through sleeve (6). Control unit according to claim 1, characterized in that the stop (12) is fastened to the back side of the front panel (1). Control unit according to claim 1 or 2, characterized in that a locking washer (11) with at least one locking hook (20) is fastened to the knob core (10) at the feed-through sleeve (6) and locks the setting-/switching knob (5) against the stop (12). Control unit according to claim 3, characterized in that the locking washer (11) in itself is springing and thereby forms the springing arrangement. Control unit according to claim 3 or 4, characterized in that the locking washer (11) has a hole with a diameter that corresponds to the diameter of the part of the knob core (10) in which the locking washer (11) shall be fastened, in that a slot (15) in the locking washer (11) at least reaches the hole and in that the width of the slot (15) is less than the diameter of the hole. Control unit according to any of the preceding claims, characterized in that a handling element (16) tightly encloses the feed-through sleeve (6) and the knob core (10) on the front of the front panel (1). Control unit according to claim 6, characterized in that the handling element (16) is provided with a bulge on the outside. Control unit according to claim 7, characterized in that the bulge is formed like a collar (22) around the handling element (16). Control unit according to any of the claims 6 - 8, characterized in that the front panel (1) is beaded (21) outwards at the feed-through sleeve (6) and in that the handling element is elastic and formed to tightly enclose the beaded (21) part of the front panel (1). Control unit according to any of the claims 6 - 8, characterized in that the front panel (1) comprises a thin protection plate (4), in that the protection plate (4) is beaded (21) outwards at the feed-through sleeve (6) and in that the handling element (16) is elastic and formed to tightly enclose the beaded (21) part of the protection plate (4).

Inventors: EDSTROEM ROLF, ERIKSSON STURE, OLSSON SVEN-GUNNAR DR, EDSTROEM, ROLF, ERIKSSON, STURE, OLSSON, SVEN-GUNNAR, DR., Edström, Rolf
Applicants: SIEMENS AG, SIEMENS ELEMA AB, SIEMENS AKTIENGESELLSCHAFT
Application year: 1991
Main classification: G05G1
IPC codes: G05G25, G05G1, A61M16, G05G5