Patent Application
20140254602
The present invention relates to capacitive couplers for non-contacting or contactless signal and data transmission systems and method and, in particular, to capacitive rotating transmission devices. Such transmission devices may be used in computer tomography (CT) scanners.
In CT scanners, a rotating x-ray tube and an x-ray detector generate high-speed imaging data. These may be transmitted from the rotating part to the stationary part of the tube. Furthermore, control signals for controlling the device and specifically the power supply of the x-ray tube may be transmitted from the stationary to the rotating part. Many applications exist where there is the need to transmit control signals between a rotor and a stator like in wind mills, revolving transfer machines, bottling plants, packaging machines or placement heads of insertion machines.
A contactless data link is disclosed in U.S. Pat. No. 6,956,450 B1. Here, binary data is fed into a transmission line at the rotating part. The transmission line has a low pass filter characteristic to suppress high frequency noise. It is terminated at its ends with the characteristic impedance of the line. Furthermore, it is split into two segments of equal length, each spanning half the circumference of a rotating structure. This transmission system cannot transfer signals, as they are required by the physical layer specification of standard communication networks such as Ethernet.
The embodiments of the invention are directed to a capacitive transmission system suitable for transmitting data of high-speed communication networks such as Ethernet, for example. The solution should be simple, inexpensive, modular, and easy to manufacture.
In an embodiment, a capacitive data link has a first part rotatable with respect to a second part. The first part may be rotating, while the second part is stationary, or the first part may be stationary while the second part is rotating. There is at least one contactless, capacitive data link between the first and the second part. Preferably, a contactless data link comprises at least one transmitter amplifier, feeding a transmitting element. Preferably, the transmitting element comprises a transmission line, which may be a strip line or any other kind of line, such as a low pass filter line, for example. The transmission line preferably has a circular shape and includes a termination section, where the transmission line is interrupted and the open ends are terminated preferably by a termination resistor. Preferably, the line is fed by the transmitter amplifier at a location opposite to the termination section, thereby dividing the transmission line into two sub-sections having almost the same length.
At the second part, there is a receiving coupler, which preferably is disposed in close proximity to the transmission line. It is configured to pick up electrical signals from the transmission line. These signals are amplified by a receiver amplifier, which is also part of the data link. Furthermore, there may be, optionally, included an encoder before the transmitter amplifier, as well as a decoder after the receiver amplifier adapted to encode signals according to a specifically defined coding scheme.
In a further embodiment, there is a plurality of data links combined in operable cooperation with at least one data processor. Preferably, there is one data processor at the first side and another data processor at the second side of the embodiment. It is preferred that each data processor have a physical layer adaptor configured to interface with a specific high speed network such as Ethernet, which may be implemented according to at least one of the following standards: 100BaseTx, 1000Base-T, and 10GBase-T. Generally, the term network used herein is also applicable to denote bus systems or high-speed bus systems. The physical layer interface may have an output to deliver signals to the transmitter amplifier and an input for receiving signals from the receiver amplifier. The output may further be connected to the encoder to encode the signals adapted to the specific need of the data link. There may further be at least one demultiplexer for dividing the signal into a plurality of sub-signals, which may be transmitted in parallel over a plurality of capacitive data links. In order to adapt to the specific physical layer, the data processor may be enabled to change the type of modulation, encoding, protocol and channel coding related to communication between the network and the contactless link.
In addition to this transmitting section, the data processor may have a receiving section adapted to receive signals from a contactless data link. The receiving section preferably has a multiplexer to multiplex a plurality of signals from a plurality of contactless data links into a single signal. There may furthermore be a decoder for decoding the previously encoded signal. The decoded signals are fed into the input of the physical layer interface. Generally, the encoder and the decoder may include devices structured to change, in operation, the coding, which may be a combination of decoder and encoder. Therefore, the first encoder in the transmitting section may also comprise a decoder for decoding the signals from the network (the signals being encoded into signals suitable for the contactless data link after decoding), which preferably are binary signals. Furthermore, the decoder in the receiving section may also comprise an encoder to encode the decoded signals into a format suitable for the high-speed network. In a preferred embodiment, the data processor, at least one receiver, and at least one transmitter and their corresponding transmit and receive antennae are cooperated to define one mechanical unit, e.g. as components located on a single printed circuit board. With the electronic components mounted to one side of a printed circuit board, the opposite side is used to hold the transmission line as transmission coupler and a receiving coupler. With two boards facing each other with their couplers mechanically configured that a transmission line forming a ring is opposite to a receiving coupler even during rotation, a contactless link can be formed out of two printed circuit board.
In the following, the invention will be described, without limitation of the general inventive concept, in reference to examples of embodiments and in reference to the drawings, of which:
While the invention can be modified without changing the scope of the invention, it is understood that the drawings and detailed description below are not intended to limit the invention to the particular form disclosed. To the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention provides capacitive rotary joints. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
