DE102007008321A1 - Optical rotary transmitter for e.g. computer scanner, has carriage with surface provided as bearings against rotor, air channel for guiding of air to surface, and adapter for supplying air into channel by connecting piece - Google Patents

Abstract

The transmitter has a rotor (10) swivelably supported against a stator (11), and a sliding carriage for holding and guiding a light coupler (5) of the stator. The sliding carriage has a storage surface (20) provided as air bearings against the rotor, an air channel for guiding air to the storage surface, and an adapter for supplying air into the air channel by a connecting piece, which is connected with the stator, where the adapter comprises flexible material.

Description

Technical area

The The invention relates to a device for transmitting optical Signals between mutually rotatable units. Such devices are preferably used in computed tomography.

State of the art

For transmission optical signals between mutually rotatable units, in particular with a free inner diameter, various devices are known. Basically, the problem here is a means for Transport of light along the circumference of the device as well as appropriate To make means for coupling and decoupling of light. For use In computed tomography such devices must be large free inner diameter of an order of magnitude of 1 meter. The peripheral speed during rotation can in the order of 20 m / s. simultaneously should have data rates in excess of 1 gigabit per second (GBaud) to be possible.

Such a device is for example in the EP 1476969 A1 disclosed. In it, light is deflected by means of a mirrored trench along the circular path and coupled out by a movable coupler. For storage, an air bearing is provided. In order to achieve a particularly precise positioning of the coupler, an electrodynamic position control is still necessary.

adversely on such a bearing arrangement is that usually hose used for air supply an undesirable force and exert an undesirable moment on the formation. This requires the air bearing with a higher air flow and a higher air pressure.

Farther must be used to mechanically bias the arrangement springs be provided, which increase the assembly costs and unwanted mechanical vibrations transmitted to the coupler. To solve the problem is in the above document proposed an electrodynamic position control.

Presentation of the invention

Of the Invention is based on the object, the above state the technology in such a way that a stable storage of the coupler with little effort, in particular without an electrodynamic position control, is reached. Furthermore, the air bearing with reduced pressure and be reduced volume flow operable. Another task The invention is to make the arrangement such that mechanical springs for bias can be omitted. A Another object is to design the arrangement in such a way that this in the idle state, that is without air supply one stable and uncritical state.

invention Solutions to this task are in the independent Claims specified. Further developments of the invention are the subject of the dependent claims.

An optical rotary transformer according to the invention comprises a rotor 10 which is opposite a stator 11 is rotatably mounted. Furthermore, a sliding carriage 13 provided, which is an optical coupler 5 for picking up light from a light guide 4 on the rotor 10 of the rotary transformer receives. The sliding carriage 13 is the stator 11 assigned. He has an outer contour, which in such a way to the rotor 10 adapted to that between the sliding carriage 13 and the rotor 10 Storage areas in the form of air bearings 20 . 21 . 22 . 23 consist. The sliding carriage 13 is with air or another gas from the pressure generating unit 24 by means of a supply air line 18 provided. This air is by means of at least one air channel 14 directed to the storage areas. By feeding air into the storage areas, a thin, viable air film is formed there. The air pressure of the air from the air line 18 must be high enough. Preferably, the bearing surfaces are closely tolerated both on the rotor and the slide side, so that the air consumption is relatively low. For connection between the supply air line 18 and the at least one air channel 14 is a neck 16 , as well as an adapter 15 intended. These are pushed into one another and thus form a variable in length line piece, which is different distances of the slide 13 from the stator 11 can adapt. Such an adaptation is necessary because due to mechanical tolerances and the movement, the distances between the rotor 10 and stator 11 can fluctuate. These variations are typically in the range of a few millimeters. However, they are no longer tolerable for optical signal transmission. For this reason, the optical coupler 5 in a sliding carriage 13 taken up, which by air storage with closest tolerances to the rotor 10 the rotary transformer can be performed. This is the optical coupler 5 itself again in a defined position with respect to the light guide 4 which is in the groove 12 is arranged. Now the sliding carriage 13 mechanically tightly coupled to the rotor 10 is guided, this moves according to the rotation in the context of mechanical tolerances, that is typically in the range of a few millimeters the stator 11 , Most of this movement 26 done perpendicular to the axis of rotation. Through the neck 16 and the adapter 15 is independent of the distance between the rotor 10 and stator 11 always an air supply of the storage areas 20 . 21 . 22 . 23 possible. For sealing between the nozzle 16 and the adapter 15 includes the adapter 15 preferably an elastic material, particularly preferably of a polymer. So this can because of its elasticity the nozzle 16 tightly enclose or inside the neck 16 close fit. The adapter 15 can also be on an inner wall of a hole 25 in the stator 11 or at least in relation to these. Alternatively, could prongs 16 and adapters 15 be made of rigid material with tight tolerances, 50 between the two is a relatively narrow air gap through which only a small amount of air can escape. In another alternative, adapters can 15 and neck 16 be interchanged. Likewise, the adapter could 15 also part of the sliding carriage 13 be. For example, a sufficiently deep hole in the sliding carriage 13 already the function of the adapter 15 fulfill.

Instead of the one described here an adapter 15 and one neck 16 Of course, you can also use several adapters 15 and several of the neck 16 be used. This is especially useful when the sliding carriage 13 has a greater length.

The adapter is preferred 15 firmly with the sliding carriage 13 connected. He slides glide over the neck 16 or the bore 25 of the stator. Likewise, but also the adapter 15 be firmly connected to the stator so that it faces a part of the slide 13 slides. Alternatively, the adapter could also compared with sliding carriage 13 and stator 11 be slidably mounted.

With a device according to the invention by adjusting the air pressure is a fine adjustment of the distance between sliding carriage 13 and stator 11 possible.

Essential to the device according to the invention is that it comprises two air bearings. A first air bearing exists between the sliding carriage 13 and the rotor 10 , The second air bearing is between the adapter 15 and the neck 16 , causing the sliding carriage 13 pressed into the first air bearing. Thus, the slide is suspended between two air bearings. As a result, in particular the air gap of the first air bearing is smaller, whereby the air consumption decreases. The second air bearing is by training with an adapter 15 and a neck 16 built so that it has no or only a negligible own air consumption. Furthermore, the second air bearing prevents lifting of the first air bearing or even rocking to vibrations during the movement, as could happen, for example, with mechanical tolerances of the concentricity.

in principle are according to the invention, the functions of rotor and Stator interchangeable, since the rotation anyway only one Question of location reference is.

In a further advantageous embodiment of the invention, the inner cross-sectional area A _{A of} the adapter 15 dimensioned such that it is greater than the product of the mass m _{G of} the sliding carriage 13 with all attached parts and the gravitational acceleration g = 9.81 m / s ² , divided by the operating pressure p _{B of} the bearing surfaces, which through the supply air line 18 is made available. Thus applies

This dimensioning ensures that a pressure on the sliding carriage 13 is exercised, which is greater than the mass of the slide 13 is. So this is always chen against the air bearing from the Lagerflä 20 . 21 . 22 . 23 pressed. This can be independent of the position of the stator 11 a pressure on the storage areas are ensured. In principle, some pressure is already present as soon as the sliding carriage is arranged downwards. In this case, he pushes by its own weight down into the rotor 10 into it. Here, by suitable dimensioning of the cross-sectional area of the adapter 15 the pressure will be further increased. Will the function of rotor 10 and stator 11 reversed, that is, the stator rotates 11 opposite a fixed rotor 10 , so must be ensured along the entire rotation, that is always a pressure of the slide 13 in the direction of the rotor 10 is available. This can easily be achieved by the dimensioning described above. According to the invention, therefore, a pressure of the sliding carriage by the air pressure, the operation of the sliding bearing from the bearing surfaces 20 . 21 . 22 . 23 is needed.

In a further advantageous embodiment of the invention, the sliding carriage 13 vertically above the axis of rotation 6 arranged so that it from below, preferably vertically from below into the profile of the rotor 10 intervenes. Thereby, as described above, a certain contact pressure by the air pressure necessary to the slide 13 engaged with the rotor 10 to keep. Now falls the air pressure from the supply air line 18 from, then the sliding carriage sinks 13 by its own weight further down to a stop. It is thus a greater distance between the slide 13 and the rotor 10 of the rotary transformer originated. As a consequence of this is also the optical coupler 5 Not more engaged with the light guide 4 , In this state, the entire rotary transformer is relatively insensitive to external shocks and can for example be transported or disassembled. It can thus easily achieve a robust and stable state of rest of the entire device.

in the Comparison to the mechanical springs required so far, with which a bias of such air bearings is generated, is by the application of air pressure a contactless power transmission realized. This has the advantage that higher frequency mechanical vibration components effectively suppressed become.

In a further advantageous embodiment of the invention is a controllable pressure generating unit 24 provided which air or other gas under pressure in the supply air line 18 fed. By the control of the pressure of the pressure generating unit can be specified. This allows an adjustment of the pressure to the operating conditions during operation.

Furthermore, it is particularly advantageous in a starting phase of the arrangement, the operating pressure from the ambient pressure or an initial pressure slowly increased within a predetermined time, so that the sliding carriage 13 slowly against the rotor 10 is pressed. This avoids that this abruptly in the direction of the rotor 10 is moved, and possibly collides with this, and thus the coupler 5 could be damaged. This can also be a rocking be prevented.

Advantageously, even in a stop phase, the operating pressure can be slowly reduced within a predetermined time from the operating pressure to an impression or to the ambient pressure, so that the sliding carriage 13 slowly from the rotor 10 off to a resting position.

Description of the drawings

The Invention will hereinafter be understood without limitation of the general Invention idea using an embodiment below Reference to the drawing described by way of example.

1 shows in general form schematically a computer tomograph

2 schematically shows an optical rotary transformer according to the invention in section

3 schematically shows an embodiment of the invention in section

4 shows a further embodiment of the invention

5 shows an inventive arrangement with a pressure generating unit

1 shows an example of a device according to the invention. The computed tomography (CT scanner) consists of two main mechanical components. A stationary part 2 serves as a base and carrier of the whole device in which the rotating part 1 rotates. The patient 104 is on a couch 107 positioned in the opening of the rotating part. To scan the patient using X-rays 102 is an x-ray tube 101 and one of these oppositely disposed detector 103 intended. X-ray tube 101 and detector 103 are on the rotating part 1 rotatably arranged. A rotary transformer 3 serves for electrical connection between the rotating part 1 and the stationary part 2 , Here, on the one hand, the high electrical power to power the X-ray tube 101 in the direction of the rotating part 1 and simultaneously transmit the raw data of the image in the opposite direction. Parallel to this, a communication of control information in both directions is provided. An evaluation and control unit 106 is used to operate the computer tomograph and to display the generated images. The communication with the computer tomograph takes place via a bidirectional connection 105 ,

2 schematically shows an optical rotary transformer according to the invention. The rotor 10 is about the axis of rotation 6 opposite the stator 11 rotatably mounted. The rotor 10 includes a light guide 4 which, for example, is a mirrored trench here. Furthermore, it has two storage areas 20 for spacing and guiding the stator. A light coupler 5 on the stator serves to tap light from the light guide 4 of the rotor. The tapped light is transmitted by means of a light-conducting fiber 7 led to a recipient. The light coupler 5 is on a sliding carriage 13 of the stator 11 arranged, with the sliding carriage 13 by means of the storage areas 20 is guided opposite the rotor.

3 shows a device according to the invention in section. The stator 11 of the rotary transformer 3 Here is an example of a U-shaped, rotationally symmetric part, which is shown here in section. The trench (the interior of the U-shaped profile) is preferably aligned with the axis of rotation of the device. But it can also be directed in the opposite direction, that is, away from the axis of rotation. The rotor 10 of the rotary transformer 3 is opposite the stator 11 rotatably mounted the Drehübertragers. Usually this is a ball bearing used. This rotor 10 the Drehübertragers can from a short arcuate segment with a typi rule length of 5 cm to 20 cm. Alternatively, a circular rotor would be feasible. This would have the advantage over a short segment-shaped rotor that completely covers the light guide and thus protects against external environmental influences.

For signal transmission is in a groove 12 the light guide 4 intended. This light guide can be, for example, a mirrored trench, preferably the groove itself, which has a mirrored surface. Likewise, another optical waveguide, such as a glass fiber or a plastic fiber may be provided. For tapping optical signals from the optical waveguide is not shown here, a coupler 5 necessary. The presentation was omitted here, as this has no effect on the functionality of the warehouse.

To guide the coupler is a sliding carriage 13 intended. This sliding carriage 13 is designed such that it forms a small air gap in the stator 11 of the rotary transformer fits. As shown in the drawing, in certain areas, for example, with respect to the light guide, or the groove 12 for receiving the light guide 4 also larger recesses may be provided. It is essential that storage areas 20 . 21 . 22 . 23 , ie areas where the sliding carriage 13 forming a small air gap on the stator 11 the rotary transformer abuts are provided. There must still be enough storage space 20 . 21 . 22 . 23 be provided in a corresponding arrangement, so that a precise guidance of the slide and thus the coupler is ensured. These storage areas are via an air duct 14 with air from a supply air line 18 provided. Instead of an air duct 14 can also be a complex channel system provided with a plurality of individual channels and outlet openings in the storage areas. For feeding the air duct is a device comprising a nozzle 16 which preferably has a smooth outer side, and an adapter 15 which preferably consists of an elastic material, for example a polymer, and with an inner side over the outside of the neck 16 slides. Furthermore, the adapter 15 with the sliding carriage 13 connected. Thus, air can now be fed from the supply air line 18 over the elbow 17 by means of the neck 16 and the adapter 15 in the air duct 14 be transported. The connection between the neck 16 and the adapter 15 is variable in length, allowing the sliding carriage 13 together with the adapter 15 a movement in the longitudinal direction of the neck 16 opposite the neck 16 and the rotor 10 of the rotary transformer can perform. By means of the exhaust air line 19 Air can be sucked out of the area of the bearing. With the elbow 17 can the space of the stator 11 be reduced, as this causes the supply air 18 can be connected to save space.

It can be here the sliding carriage as with the arrow 26 indicated with respect to the stator to move to and from this.

4 shows a further embodiment of the invention. This is the adapter 15 differently trained than in 2 , While he is in 2 at the neck 16 rests, he seals here opposite the housing part of the stator 11 from. This can be done either by a flat attachment or by a lip, as in 3 shown, taken in a hole 25 is applied. Thus, here also the sliding carriage as with the arrow 26 indicated, with respect to the stator to move to or from this.

5 shows the invention with connected pressure generating unit 24 , This pressure generating unit 24 provides air or other gas under increased pressure relative to the environment by means of the supply air line 18 over the air channels 14 of the slide 13 to the storage areas 20 . 21 . 22 . 23 , Optionally, the pressure generating unit sucks 24 Air via the exhaust air line 19 from the space between rotor and stator. This results in a closed air circuit into which no dirt can penetrate from the outside. Additionally or alternatively, the Druckzeugungsein unit 24 also suck in air from the free space or the environment of the arrangement. Advantageously, at least one air filter is provided, which via the air supply line 18 supplied air or from the exhaust ducts 19 or filtered by the environment filtered air.

1

rotating part

2

stationary part

3

Rotary joint

4

optical fiber

5

light coupler

6

axis of rotation

7

photoconductive fiber

10

rotor of the rotary transformer

11

stator of the rotary transformer

12

groove for receiving the light guide

13

Sliding carriage

14

air duct

15

adapter

16

Support

17

elbow

18

air supply

19

exhaust duct

20

first storage area

21

second storage area

22

third storage area

23

fourth storage area

24

Pressure generating unit

25

drilling

26

movement direction of the slide

101

X-ray tube

102

X-rays

103

detector

104

patient

105

bidirectional connection

106

evaluation and control unit

107

patient support

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1476969 A1 [0003]

Claims (10)

Optical rotary transformer comprising a rotor ( 10 ) with a light guide ( 4 ) and a stator ( 11 ) with a light coupler ( 5 ), wherein the rotor ( 10 ) opposite the stator ( 11 ) is rotatably mounted, characterized in that a sliding carriage ( 13 ) for receiving and guiding the light coupler ( 5 ) is provided, wherein the sliding carriage ( 13 ) at least one storage area ( 20 . 21 . 22 . 23 ) as an air bearing against the rotor ( 10 ), at least one air duct ( 14 ) for guiding air to the at least one storage area ( 20 . 21 . 22 . 23 ), and at least one adapter ( 15 ) for feeding air into the at least one air duct ( 14 ) by means of at least one nozzle ( 16 ), which with the stator ( 11 ). Apparatus according to claim 1, characterized in that the at least one adapter ( 15 ) comprises an elastic material. Apparatus according to claim 1 or 2, characterized in that the at least one adapter ( 15 ) on an inside or outside of the at least one connecting piece ( 16 ) or at least one bore in the stator ( 11 ) is present. Device according to one of the preceding claims, characterized in that the internal cross-sectional area A _{A of} the adapter ( 15 ) is greater than the product of the mass m _{G of} the sliding carriage ( 13 ) with all the parts attached thereto and the gravitational acceleration g = 9.81 m / s ² , divided by the operating pressure p _{B of} the bearing surfaces, which through the nozzle ( 16 ) to the adapter ( 15 ) is delivered. Device according to one of the preceding claims, characterized in that the sliding carriage ( 13 ) vertically above the axis of rotation ( 6 ) is arranged. Device according to one of the preceding claims, characterized in that the sliding carriage ( 13 ) falls vertically downwards into a rest position without the application of compressed air. Device according to one of the preceding claims, characterized in that a pressure generating unit ( 24 ) is provided, which by means of a supply air line ( 18 ) Air or another gas into the nozzle ( 16 ) promotes. Device according to one of the preceding claims, characterized in that the pressure generating unit controllable is. Device according to one of the preceding claims, characterized in that the pressure generating unit in a Starting phase based on the ambient pressure or an initial pressure the Pressure continuously within a given time to one Operating pressure increased. Device according to one of the preceding claims, characterized in that the pressure generating unit in a Stop phase, starting from the operating pressure, the pressure continuously within a predetermined time to ambient pressure or a Final pressure reduced.