Non-contact slip ring probe with graduated frequency response

Abstract

A probe for receiving electrical signal transmissions from a transmitter across a slip ring interface includes a signal acquisition area including at least one segmented signal receiving strip positioned in spaced relation to the slip ring transmitter for receiving signals transmitted across the slip ring interface, the segmented signal receiving strip configured to receive a range of frequency signal content of signals and including a first signal receiving segment having a first frequency response, a second signal receiving segment electrically coupled to the first signal receiving segment and having a second frequency response below the first frequency response, and a third signal receiving segment coupled to the first signal receiving segment and having a third frequency response below the first frequency response.

Description

[Technical field]

[0001] The present invention relates to slip ring probes and, more particularly, to slip ring with segmented graduated frequency response probes. [Background technology]

[0002] Devices for transmitting electrical signals between two members that are rotatable relative to one another are well known in the art. Such devices, commonly known as rotary joints or rotary electrical interfaces, include slip rings and twist capsules, among others. Slip rings are typically used when unlimited rotation between the members is required, whereas twist capsules are typically used when only limited rotation between the members is required.

[0003] Slip rings allow the transmission of power and signals, including data, from a stationary to a rotating structure or between two structures that are rotating relative to each other. Slip rings can be used in any electromechanical system that requires rotation while transmitting power or signals. Slip rings can also improve mechanical performance, simplify system operation, and eliminate susceptible wires dangling from moving joints. Traditionally, slip rings are designed only for the transmission of data over a very small portion of the slip ring area.

[0004] Conventional slip rings typically use sliding electrical contacts between members. While these work well in certain applications, they have inherent deficiencies that limit electrical performance at higher frequencies. Non-contact slip rings are also known in the art. Such rotary joint systems allow the transmission of high frequency electrical signals between a rotor and a stator without sliding electrical contacts. Such non-contact systems include a device for recovering electromagnetic energy transmitted across space between a signal source and a signal receiver. In radio frequency ("RF") communication systems, such devices are called antennas (or antenna effects) and typically operate in classical far-field electromagnetic radiation in free space. In contrast, rotary joints that utilize electromagnetic near-fields to effect electrical communication over very short distances and recover energy from electromagnetic near-fields are referred to as "electric field probes" or simply "probes."

[0005] Devices intended to function in the reactive near field of an electromagnetic source take different forms than the far field devices with magnetic loops, voltage probes, and resistively loaded dipoles known in the prior art. Near field applications include RF ID tags and secure low speed data transfer, which utilize magnetic induction in the near field. As used herein, a "probe" is a structure that operates in the near field of an electromagnetic source, and an "antenna" is intended to refer to a radiating structure that is primarily intended to be a far field device. The subject matter of this disclosure includes electromagnetic field probes that operate in the near field of a non-contact rotary junction, such as a slip ring.

[0006] Conventional antennas and near-field probes exhibit a variety of behaviors that prevent or impair their use in non-contact rotary junction systems when operating at data transmission rates above 1 Gbps. Such rotary junction systems are required to exhibit an ultra-wideband ("UWB") frequency response to pass the required frequency components of multi-gigabit digital data, as well as high return loss and low distortion impulse response to preserve the time domain characteristics of the signal. In addition, non-contact rotary junctions exhibit characteristics that complicate the design of antennas and electric field probes required to capture the energy transmitted across the rotating gap. Typically, non-contact rotary junctions exhibit field strength variations due to rotation between the rotor and stator, directional behavior as the signal travels as a wave in the transmission line from the signal source to the transmission line termination, and may even exhibit discontinuities in the near field. High frequency non-contact rotary junctions pose a unique set of challenges for the design of near-field probes.

[0007] Most prior art antennas and probes are narrowband standing wave devices that lack both the frequency and time domain response to accommodate the wideband energy of multi-gigabit data streams. Small near-field voltage and current probes may exhibit reasonable frequency and impulse responses, but often lack sufficient acquisition area for an acceptable signal-to-noise ratio.

[0008] No. 10,033,074 discloses a non-contact rotary junction for transmitting electrical signals across an interface defined between two relatively movable members that addresses some of the shortcomings of previous rotary junction solutions. The non-contact rotary junction broadly includes a signal source operatively arranged to provide a high speed digital data output signal, an impedance-controlled differential transmission line having a source gap and a termination gap, a power splitter operatively arranged to receive the high speed digital data output signal from the signal source and to supply the high speed digital data output signal to the source gap of the impedance-controlled differential line, a near field probe disposed in spaced relationship to the transmission line to receive the signal transmitted across the interface, and receive electronics operatively arranged to receive the signal received by the probe.

[0009] No. 7,142,071 discloses a velocity compensated contact ring system including a first dielectric material, a plurality of coaxially spaced apart conductive rings, and a first ground plane. The first dielectric material includes a first side and a second side. The plurality of coaxially spaced apart conductive rings are located on the first side of the first dielectric material. The conductive rings include an inner ring and an outer ring. The first ground plane is located on the second side of the first dielectric material. The width of the inner ring is greater than the width of the outer ring, and the widths of the inner and outer rings are selected to make the electrical lengths of the inner and outer rings approximately equal.

[0010] U.S. Patent No. 6,956,445 discloses a contact probe system including at least one flat brush contact and a printed circuit board (PCB). The PCB includes a supply line for coupling the flat brush contact to an external interface. The flat brush contact is located on a first side of the PCB, and the PCB includes a plated through hole interconnecting the flat brush contact to the supply line. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 10,033,074 [Patent Document 2] U.S. Patent No. 7,142,071 [Patent Document 3] U.S. Patent No. 6,956,445 Summary of the Invention [Means for solving the problem]

[0012] For purposes of illustration only and not limitation, and with parenthetical notations to corresponding components, portions, or surfaces of the disclosed embodiments, a non-contact rotary joint (115, 215) for transmitting an electrical signal (30) across a non-contact interface (60) defined between two relatively movable members is provided. The non-contact rotary junction includes a transmitter (16) configured to transmit a signal (30) across a non-contact interface (60), and a near-field probe (18) disposed in spaced relation to the transmitter and operatively arranged to receive the signal transmitted across the interface, the near-field probe having a signal acquisition area (100, 200, 300) for receiving the signal transmitted across the interface, the signal acquisition area having a length sized for a desired low frequency signal content of the signal and comprising segmented signal receiving strips (110, 130, 210, 230, 310, 330) configured to receive a range of frequency signal content of the signal including the desired low frequency signal content of the signal, the segmented signal receiving strips receiving a first signal having a first frequency response. a signal receiving segment (119, 219, 319) having a second frequency response and electrically coupled to the first signal receiving segment, a second signal receiving segment (111A, 211A, 311A) having a second frequency response and electrically coupled to the first signal receiving segment, and a third signal receiving segment (111B, 211B, 311B) having a third frequency response and electrically coupled to the first signal receiving segment, the second frequency response of the second signal receiving segment being lower than the first frequency response of the first signal receiving segment and the third frequency response of the third signal receiving segment being lower than the first frequency response of the first signal receiving segment; and receiving electronics (28) operatively arranged to receive a range of frequency signal content received by the segmented signal receiving strip via the first signal receiving segment (119, 219, 319).

[0013] The first signal receiving segment may have a first length, the second signal receiving segment may have a second length that exceeds the first length, and the third signal receiving segment may have a third length that exceeds the first length. The segmented signal receiving strip may comprise a first dissipative element (121A, 221A, 314A) positioned between the first and second signal receiving segments and configured to isolate the first signal receiving segment from the second signal receiving segment, and a second dissipative element (121B, 221B, 314B) positioned between the first and third signal receiving segments and configured to isolate the first signal receiving segment from the third signal receiving segment.

[0014] The second signal receiving segment (311A) may comprise an electrically coupled resistor (R) and capacitor (C) arranged to provide a signal filter (321A), and the third signal receiving segment (311B) may comprise an electrically coupled resistor and capacitor arranged to provide a signal filter (321B). The first signal receiving segment (319) may have a first length, the second signal receiving segment (311A) may have a second length equal to the first length, and the third signal receiving segment (311B) may have a third length equal to the first length. The segmented signal receiving strip (310) may comprise a first dissipative element (314A) positioned between the first signal receiving segment (319) and the second signal receiving segment (311A) and configured to isolate the first signal receiving segment from the second signal receiving segment, and a second dissipative element (314B) positioned between the first signal receiving segment (319) and the third signal receiving segment (311B) and configured to isolate the first signal receiving segment from the third signal receiving segment.

[0015] The first signal receiving segment, the second signal receiving element, and the third signal receiving element may each include copper. The first dissipative element and the second dissipative element may each include a resistor. The first signal receiving segment (119, 219, 319) may include a center tap (61) in communication with the receiving electronics (28).

[0016] The first frequency response of the first signal receiving segment can correspond to a first frequency sub-range of the range of frequency signal content of the signal, and the second frequency response of the second signal receiving segment can correspond to a second frequency sub-range of the range of frequency signal content of the signal, and the first frequency sub-range can be greater than the second frequency sub-range.

[0017] The signal transmitted by the transmitter across the contactless interface may be a high speed digital data output signal. The transmitter comprises a signal source (20) operatively arranged to provide the high speed digital data output signal, an impedance-controlled differential transmission line (162) having a source gap (23) and a termination gap (24), and a power splitter (21) operatively arranged to receive the high speed digital data output signal from the signal source and to supply the high speed digital data output signal from the signal source to the source gap of the impedance-controlled differential transmission line, and the near field probe may be disposed in a spaced relationship to the impedance-controlled differential transmission line and operatively arranged to receive the signal transmitted by the transmitter across the contactless interface.

[0018] The segmented signal receiving strip may comprise at least two further signal receiving segments (112A, 112B, 113A, 113B, 311), each of the further signal receiving segments having a frequency response and electrically coupled to the first signal receiving segment, where the frequency response of each further signal receiving segment decreases the further the further the signal receiving segment is from the first signal receiving segment. The segmented signal receiving strip may comprise at least one dissipative element (121A, 122A, 123A, 121B, 122B, 123B, 221A, 222A, 223A, 221B, 222B, 223B, 314A, 314B, 314) positioned between each of the second, third and further signal receiving segments, where the dissipative element may be configured to isolate each of the signal receiving segments from each other.

[0019] The length of each further signal receiving segment (112A, 112B, 113A, 113B) may increase the further the further signal receiving segment is from the first signal receiving segment (119, 219). The second signal receiving segment (311A), the third signal receiving segment (311B) and the further signal receiving segment (311) may comprise an electrically coupled resistor (R) and capacitor (C) arranged to provide a signal filter (321).

[0020] The signal acquisition area comprises a second segmented signal receiving strip (130, 230, 330) oriented parallel to the first segmented signal receiving strip (110, 210, 310), the second segmented signal receiving strip comprising a first signal receiving segment (139, 239, 339) having a first frequency response, a second signal receiving segment (131A, 231A, 331A) having a second frequency response and electrically coupled to the first signal receiving segment, and a third signal receiving segment (131A, 231A, 331A) having a third frequency response and electrically coupled to the first signal receiving segment. The second segmented signal receiving strip (130, 230, 330) may include a second frequency response of the second signal receiving segment that is lower than the first frequency response of the first signal receiving segment and a third frequency response of the third signal receiving segment that is lower than the first frequency response of the first signal receiving segment, and the receiving electronics (28) may be operatively arranged to receive signal content received by the second segmented signal receiving strip (130, 230, 330) via the first signal receiving segment (139, 239, 339) of the second segmented signal receiving strip (130, 230, 330).

[0021] In another aspect, a probe is provided having a length sized for desired low frequency signal content, the probe comprising a plurality of signal receiving strips (110, 130, 210, 230, 310, 330) configured to receive low frequency and high frequency signal content, each of the plurality of signal receiving strips including a center tap (61, 62, 119, 139, 219, 239, 319, 339) connected to a processor (28), a first signal receiving segment (111A, 211A, 311A) including a length for receiving high frequency signals, a second signal receiving segment (111A, 211A, 311A) including a length for receiving high frequency signals, and a third signal receiving segment (111B, 211B) including a length for receiving high frequency signals. a second signal receiving segment (111B, 211B, 311B) including a length, a first dissipative element (121A, 221A, 314A) positioned between the center tap and the first signal receiving segment to isolate the center tap and the first signal receiving segment, and a second dissipative element (121B, 221B, 314B) positioned between the center tap and the second signal receiving segment to isolate the center tap and the second signal receiving segment.

[0022] The plurality of signal receiving strips may further comprise at least one first additional signal receiving segment (112A, 113A, 212A, 213A) including a length for receiving a high frequency signal, the first additional signal receiving segment being electrically coupled to the first signal receiving segment, and at least one second additional signal receiving segment (112B, 113B, 212B, 213B) including a length for receiving a high frequency signal, the second additional signal receiving segment being electrically coupled to the second signal receiving segment. The plurality of signal receiving strips may further comprise a center tap and a plurality of dissipative elements (122A, 123A, 222A, 223A) positioned between the signal receiving segments to isolate the signal receiving segments. The length of each corresponding signal receiving segment (112A, 113A, 212A, 213A, 112B, 113B, 212B, 213B) may increase the further the signal receiving segment is from the center tap. Each of the signal receiving segments may correspond to a range of frequency signal content. The first and second signal receiving segments may include a copper conductive material. The first and second signal receiving segments (311A, 311B) may be electrically coupled to a resistor (R) and capacitor (C) filter (321). The first and second signal receiving segments may be 0.11 inches by 0.075 inches.

[0023] In another aspect, a method of receiving low and high frequency signal content is provided, the method including: providing a probe including a length sized for desired low frequency signal content, the probe including a plurality of signal receiving strips configured to receive low and high frequency signal content, each of the plurality of signal receiving strips including a center tap connected to a processor, a first signal receiving segment including a length for receiving a high frequency signal, a second signal receiving segment including a length for receiving a high frequency signal, a first dissipative element positioned between the center tap and the first signal receiving segment to isolate the center tap and the first signal receiving segment, and a second dissipative element positioned between the center tap and the second signal receiving segment to isolate the center tap and the second signal receiving segment, and receiving the low and high frequency signal content by the first and second signal receiving segments.

[0024] Each of the plurality of signal receiving strips may further comprise at least one first additional signal receiving segment including a length for receiving a high frequency signal, the first additional signal receiving segment being electrically coupled to the first signal receiving segment, and at least one second additional signal receiving segment including a length for receiving a high frequency signal, the second additional signal receiving segment being electrically coupled to the second signal receiving segment. Each of the plurality of signal receiving strips may further comprise a plurality of dissipative elements positioned between the signal receiving segments to isolate the center tap and the signal receiving segments. The length of each corresponding signal receiving segment may increase the further the signal receiving segment is from the center tap. Each of the signal receiving segments may correspond to a range of frequency signal content. The first signal receiving segment and the second signal receiving segment may be made of a copper conductive material. The first signal receiving segment and the second signal receiving segment may be electrically coupled to a resistor and a capacitor. The first signal receiving segment and the second signal receiving segment may be 0.279 cm (0.11 inches) by 0.191 cm (0.075 inches).

[0025] In another aspect, a slip ring probe (100, 200, 300) is provided that includes a plurality of conductive strips (110, 120, 210, 230, 310, 330) disposed in a spaced relationship to a transmitter (162) of the slip ring (115, 215) for receiving a signal (30) transmitted across an interface (60) of the slip ring (115, 215). Each of the plurality of conductive strips (110, 120, 210, 230, 310, 330) has a center tap (61, 62, 113, 123, 219, 239, 319, 330) and a length (132, 252) capable of providing a coupling capacitance across the entire length of the plurality of conductive strips (110, 120, 210, 230, 310, 330) between the transmitter (162) and the probe (100, 200, 300) of the slip ring (115, 215).

[0026] The probe may be a stepped frequency response probe (100, 200, 300). Each of the plurality of conductive strips (110, 120, 210, 230, 310, 330) may include a variable loss tangent (131, 251) over each length (132, 252) of each of the plurality of conductive strips (110, 120, 210, 230, 310, 330). The variable loss tangent (131, 251) over each length (132, 252) of each of the plurality of conductive strips (110, 120, 210, 230, 310, 330) may increase toward an outer region of the plurality of conductive strips (110, 120, 210, 230, 310, 330). The variable loss tangent (131, 251) may be smallest at a center tap (61, 62, 113, 123, 219, 239, 319, 339) of each of the plurality of conductive strips (110, 120, 210, 230, 310, 330). The respective lengths (132, 252) of each of the plurality of conductive strips (110, 120, 210, 230, 310, 330) may be selected based on the frequency of the signal (30). Each of the plurality of conductive strips (110, 120, 210, 230, 310, 330) may include a signal capture area. The signal capture area may correspond to a coupling capacitance such that a larger signal capture area results in a larger coupling capacitance. Each of the plurality of conductive strips (110, 120, 210, 230) may include a plurality of discrete attenuation filters (111A, 111B, 112A, 112B, 113A, 113B, 211A, 211B, 212A, 212B, 213A, 213B). The length of each of the plurality of discrete attenuation filters may increase away from a center tap (61, 62, 113, 123, 219, 239) of the probe (100, 200). The length of each of the plurality of discrete attenuation filters (111A, 111B, 112A, 112B, 113A, 113B, 211A, 211B, 212A, 212B, 213A, 213B) may correspond to a frequency bandwidth.The probe (100, 200, 300) may include resistors (121A, 122A, 123A, 121B, 122B, 123B, 221A, 222A, 223A, 221B, 222B, 223B, 314A, 314B, 314) disposed between adjacent attenuation filters of the plurality of discontinuous attenuation filters. The probe (100, 200) may further include pads (115A, 115B, 135A, 135B, 215A, 215B, 235A, 235B) at the respective ends of the plurality of conductive strips (110, 120, 210, 230) for attenuating frequencies. The probe (100, 200, 300) may be a straight probe or a curved probe. The length (132, 252) of the conductive strips (110, 120, 210, 230) may be proportional to the wavelength of the electrical signal (30) across the slip ring (115, 215) interface (60), where lower frequencies of the signal (30) may correspond to longer lengths of the conductive strips (110, 120, 210, 230) to increase the coupling capacitance of the probe (100, 200). The receiver may be configured to receive low frequencies of the signal across most of the length (132, 252) of the conductive strips (110, 120, 210, 230, 310, 330) and higher frequencies in an area proximate to the center tap (113, 123, 219, 239, 319, 339) of the conductive strips (110, 120, 210, 230, 310, 330). [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a first embodiment of an improved non-contacting rotary joint, showing, among other things, a non-contacting rotary joint ("NCRJ") system diagram for transmitting a transmitter (TX) signal from a data transmitting side to a data receiving side. Conventional positive (+) and negative (-) symbols are shown to illustrate differential signals and transmission lines. [Diagram 2] FIG. 2 is a top view of the circular platter circuit board transmitter of the slip ring shown in FIG. 1, with the transmission tracks in a circular configuration. [Diagram 3]FIG. 2 is a top view of the receiver and probe of the circular platter circuit board of the slip ring shown in FIG. 1, with the conductive strips in a circular curved platter configuration. [Figure 4] 4 is an enlarged top view of a pair of conductive strips of the probe shown in FIG. 3. [Diagram 5] FIG. 2 is a perspective view of a second embodiment of a non-contact slip ring transmitter and receiver with the transmission tracks and conductive strips in a linear configuration. [Figure 6] FIG. 6 is an enlarged plan view of the conductive strip of the probe shown in FIG. 5 with the corresponding loss tangent graph. [Figure 7] 5A-5C are receiver eye diagrams for the slip ring probe of FIG. 4 at different frequencies. [Figure 8] FIG. 5 is an enlarged top view of an alternative embodiment of the probe shown in FIG. 4. [Figure 9] FIG. 9 is a schematic circuit diagram of the 10-segment probe shown in Figure 8. [Figure 10] FIG. 13 is an enlarged top view of a typical slip ring probe with corresponding loss tangent graph. [Figure 11A] FIG. 1 illustrates the signal transmission of a probe for low frequency content. [Figure 11B] FIG. 1 illustrates the signal transmission of a probe for high frequency content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] At the outset, it should be clearly understood that like reference numbers are intended to identify the same structural elements, parts, or surfaces consistently throughout the several drawings, because such elements, parts, or surfaces may be further described or explained by the entire specification, and this detailed description is an integral part of this specification. Unless otherwise specified, the drawings (e.g., cross-hatching, arrangement of parts, proportions, extent, etc.) are intended to be read together with the specification and should be considered as part of the entire specification of the present invention. As used in the following description, the terms "horizontal", "vertical", "left", "right", "upper", and "lower", as well as their adjectival and adverbial derivatives (e.g., "horizontally", "to the right", "upward", etc.) simply refer to the orientation of the structures shown when a particular drawing is facing the reader. Similarly, the terms "inwardly" and "outwardly" generally refer to the orientation of a surface relative to its axis of elongation or rotation, as appropriate.

[0029] Non-contact slip ring probe structures used for data transfer respond differently at different data rates. Probes designed to perform at a particular data rate and protocol will not perform well for other data rates and protocols. Furthermore, even optimized probes exhibit waveform distortion as they move along a rotary or linear data source track, especially where the track is discontinuous. This leads to poor received signal quality at the detector and an increased signal (bit) error rate (BER).

[0030] Referring now to the drawings, and more particularly to Figures 1-4 of the drawings, a first embodiment of a slip ring is provided, generally designated 115. The slip ring 115 is a contactless rotary junction for the transmission of high speed data signals across an intervening interface between two relatively movable members without the use of sliding electrical contacts in the signal path. The junction includes a split differential microstrip transmission line driven by a signal source through a power splitter and resistively terminated at the far end, and a receiver including a planar differential electromagnetic field probe that senses the near field of the transmitter differential microstrip and delivers the recovered signal energy to an electronic receiver for detection. This high speed contactless rotary junction can be implemented with printed circuit board ("PCB") technology and can support multi-gigabit data transmission speeds with frequency domain bandwidth.

[0031] As shown in FIG. 1, a signal source 20 serves to send a high-speed digital data signal to a power splitter 21 (which may be active or passive), where the signal travels through a source gap 23 to an impedance-controlled differential transmission line 162. The signal also propagates as a transverse electromagnetic wave ("TEM") on a differential transmission line ring structure of the line 162 of the transmitter circuit board 16, until the signal is terminated at a far-end termination gap 24 by a wideband termination technique 25. The TEM signal traveling on the ring transmission line 162 is sampled in the near field by an ultra-wideband planar segmented GFR near-field probe signal acquisition area 100 of the receiver circuit board 18, which is suspended at a distance above the transmitter 16 and the ring structure 162 so that the rotary junction can rotate freely without physical contact. Thus, as shown, the probe signal acquisition area 100 is suspended a short distance above an impedance controlled differential transmission line 162. The signal 30 recovered across the air gap 60 by the near field probe 100 is sent to the receive electronics 28 of the receiver 18 where it can be detected and amplified and the data can be recovered.

[0032] The data source driver 20 may be any of a number of technologies capable of the desired data rate, including current-mode logic ("CML"), field-programmable gate array ("FPGA"), low-voltage differential signaling ("LVDS") devices, and other discrete devices. The data signal is split into two equal amplitude, phase-inverted signals for feeding into the differential ring system, a function that may be performed by a passive resistive divider or active techniques (e.g., a CML fan-out buffer). The power divider 21 may be implemented as a discrete assembly or, in this embodiment, may be incorporated onto the PCB structure of the transmitter 16 with discrete or integrated components or embedded passive components implemented in a flat PCB geometry. The technology used to implement the power divider imposes constraints on high frequency operation of the data channel due to the parasitic reactance of the component packages that result in signal reflections that become increasingly more significant at higher frequencies. The drive electronics, power dividers, and transmission line terminations can be implemented using a variety of technologies (e.g., through-hole or surface mount components on the PCB structure, integrated components, or embedded passives implemented in flat PCB geometries) whose capabilities for high frequency performance are determined by reducing parasitic reactance.

[0033] The ring structure 162 of the transmitter 16 in the non-contact rotary junction 115 is a non-resonant, discontinuous, impedance-controlled differential transmission line typically implemented with microstrip multi-layer printed circuit board technology. The nature of the ring transmission line 162 is such that most of the signal energy is contained in the near field of the conductors. Energy radiated from the structure tends to cancel in the far field, helping to suppress electromagnetic interference (EMI). Signals propagating on the ring system are directional.

[0034] The near-field probe 100 of the receiver 18 is designed to have an ultra-wideband near-field response while meeting the specific requirements of high-speed data transmission over a ring transmission line 162. The receiver 18 is shown broadly comprising a PCB having multiple pairs of parallel segmented conductive strips 100 on one side. Each pair of segmented conductive strips 100 includes a first segmented conductive strip 110 and a second segmented conductive strip 130. The first conductive strip 110 and the second conductive strip 130 each have a length corresponding to the desired low frequency domain of the receiver and are configured to receive signals from the transmitter 160 across the gap 60 of the rotary junction 115.

[0035] The first conductive strip 110 comprises a central conductive pad 119, conductive pads 111A, 112A, and 113A extending from the central pad 119 towards an end 116, an end capacitive element 115A defining the end 116, conductive pads 111B, 112B, and 113B extending from the central pad 119 towards an end 118, and an end capacitive element 115B defining the end 118. The central conductive pad 119 has a central via or tap 61 which connects to a first stage amplifier of the signal receive electronics 28 of the receiver board 18. Each of central conductive pad 119, conductive pads 111A, 112A, and 113A, end capacitive element 115A, conductive pads 111B, 112B, and 113B, and end capacitive element 115B are separated from each other by resistors 121A, 121B, 122A, 122B, 123A, 123B, 124A, and 124B, respectively.

[0036] Similarly, the second conductive strip 130 extends from a first end 136 to a second end 138. The second conductive strip 130 includes a central conductive pad 139, conductive pads 131A, 132A, and 133A extending from the central pad 139 toward the end 136, an end capacitive element 135A defining the end 136, conductive pads 131B, 132B, and 133B extending from the central pad 139 toward the end 138, and an end capacitive element 135B defining the end 138. The central conductive pad 139 has a central via or tap 62 that connects to a first stage amplifier of the signal receiving electronics 28 of the receiver board 18. Each of central conductive pad 139, conductive pads 131A, 132A, and 133A, end capacitive element 135A, conductive pads 131B, 132B, and 133B, and end capacitive element 135B are separated from each other by resistors 141A, 141B, 142A, 142B, 143A, 143B, 144A, and 144B, respectively.

[0037] Thus, the first conductive strip 110 of the probe 100 is not continuous, but instead is formed from a plurality of segments 119, 111A, 111B, 112A, 112B, 113A, and 113B, a plurality of resistors 121A, 121B, 122A, 122B, 123A, 123B, 124A, and 124B, a first capacitive end 115A, and a second capacitive end 115B. As shown in FIG. 4 and further described below with respect to embodiment 200, in this embodiment, the segments 111A and 111B, 112A and 112B, and 113A and 113B vary in length such that the segment length increases with increasing distance from the central segment 119 and central via 61. Thus, central segment 119 has a median length, segments 111A and 111B have a first length that exceeds the median length of central segment 119, segments 112A and 112B have a second length that exceeds the first length of segments 111A and 111B, and segments 113A and 113B have a third length that exceeds the second length of segments 112A and 112B. Due to this difference in length, conductive segments 111A and 111B, 112A and 112B, and 113A and 113B have different frequency responses depending on their location relative to central segment 119. Such conductive segments have frequency responses that decrease with distance from or location relative to the central segment, such that segments 113A and 113B have the lowest response to high frequency signal components and central segment 119 has the highest response to high frequency signal components. The overall strip length, individual segment lengths, and number of segments of conductive strip 110 may vary depending on the frequency range desired for receiver 18.

[0038] 4 and described further below with respect to embodiment 200, in this embodiment resistors 121A, 121B, 122A, 122B, 123A, 123B, 124A, and 124B also vary in length such that the length of the resistor increases with increasing distance from central tab 119 and central via 62. Thus, resistors 121A and 121B between central segment 119 and segments 111A and 111B, respectively, have a first length, resistors 122A and 122B between segments 111A and 111B and segments 112A and 112B, respectively, have a second length that exceeds the first length of resistors 121A and 121B, and resistors 123A and 123B between segments 112A and 112B and segments 113A and 113B, respectively, have a third length that exceeds the second length of resistors 122A and 122B, respectively. Resistors 124A and 124B between segments 113A and 113B and ends 115A and 115B of the small end capacitance, respectively, serve to dissipate high frequency signal components propagated towards ends 116 and 118 of conductive strip 110. Resistors 121A, 121B, 122A, 122B, 123A, and 123B are configured to have values ​​set to attenuate frequencies of interest at these locations along strip 110. In this embodiment, resistors 123A and 123B are configured to allow low frequency signal components to pass from conductive segments 113A and 113B to conductive segments 112A and 112B, respectively, but not higher frequency signal components. Dual resistors 122A and 122B are then configured to allow intermediate high frequency signal components to pass from conductive segments 112A and 112B to conductive segments 111A and 111B, respectively, but not higher frequency signal components. Resistors 121A and 121B are then configured to allow intermediate frequency signal components to pass from conductive segments 111A and 111B, respectively, to conductive segment 119, but not higher frequency signal components. The resistor values, individual resistor lengths, and number of resistors can vary depending on the frequency range and attenuation desired for receiver 18.

[0039] Similarly, the second conductive strip 130 of the probe 100 is not continuous, but instead is formed from a plurality of segments 139, 131A, 131B, 132A, 132B, 133A, and 133B, a plurality of resistors 141A, 141B, 142A, 142B, 143A, 143B, 144A, and 144B, a first capacitive end 135A, and a second capacitive end 135B. As shown in FIG. 4 and further described below with respect to embodiment 200, in this embodiment, the segments 131A and 131B, 132A and 132B, and 133A and 133B vary in length such that the segment length increases with increasing distance from the central segment 139 and central via 62. Thus, central segment 139 has a median length, segments 131A and 131B have a first length that exceeds the median length of central segment 139, segments 132A and 132B have a second length that exceeds the first length of segments 131A and 131B, and segments 133A and 133B have a third length that exceeds the second length of segments 132A and 132B. Due to this difference in length, conductive segments 131A and 131B, 132A and 132B, and 133A and 133B have different frequency responses depending on their location relative to central segment 139. Such conductive segments have frequency responses that decrease with distance from or location relative to the central segment, such that segments 133A and 133B have the lowest response to high frequency signal components and central segment 139 has the highest response to high frequency signal components. The overall strip length, individual segment lengths, and number of segments of conductive strip 130 may vary depending on the frequency range desired for receiver 18.

[0040] 4 and described further below with respect to embodiment 200, in this embodiment resistors 141A, 141B, 142A, 142B, 143A, 143B, 144A, and 144B also vary in length such that the length of the resistor increases with distance from central segment 139 and central via 62. Thus, resistors 141 and 141B between central segment 139 and segments 131A and 131B, respectively, have a first length, resistors 142A and 142B between segments 131A and 131B and segments 132A and 132B, respectively, have a second length that exceeds the first length of resistors 141A and 141B, and resistors 143A and 143B between segments 132A and 132B and segments 133A and 133B, respectively, have a third length that exceeds the second length of resistors 142A and 142B, respectively. Resistors 144A and 144B between segments 133A and 133B and ends 135A and 135B of the small end capacitance, respectively, serve to dissipate high frequency signal components propagated towards ends 136 and 138 of conductive strip 130. Resistors 141A, 141B, 142A, 142B, 143A, and 143B are configured to have values ​​set to attenuate frequencies of interest at these locations along strip 130. In this embodiment, resistors 143A and 143B are configured to allow low frequency signal components to pass from conductive segments 133A and 133B to conductive segments 132A and 132B, respectively, but prevent higher frequency signal components from passing. Dual resistors 142A and 142B are then configured to allow intermediate high frequency signal components to pass from conductive segments 132A and 132B to conductive segments 131A and 131B, respectively, but prevent higher frequency signal components from passing. Resistors 141A and 141B are then configured to allow intermediate frequency signal components to pass from conductive segments 131A and 131B, respectively, to conductive segment 139, but not higher frequency signal components. The resistor values, individual resistor lengths, and number of resistors can vary depending on the frequency range and attenuation desired for receiver 18.

[0041] Thus, the slip ring 115 includes a longer transmission strip 162 of PCB material, and a shorter differential conductive receiving probe signal acquisition area 100. The transmission strip and receiving probe 100 are placed in close proximity, and the signal on the transmission strip 162 is typically capacitively coupled to the receiving probe 100 across the air gap 60. The signal is amplified by a first stage amplifier 50 and sent to the communications receive circuitry 28. The traces are typically organized as differential tracks to reduce EMC effects, although single tracks are contemplated as well.

[0042] As shown in Figure 2, the transmitter 16 has a circular flat platter configuration with four channels 162 oriented about the center. As shown in Figure 3, the receiver 18 is similarly configured as a circular platter circuit board with four probe channels 100 with curved conductive strips 110, 130 oriented about the center. The transmitter 16 and receiver 118 are coaxial such that the receiving probes 100 for each channel are aligned radially across the air gap 60 from the corresponding channel transmission track 162 of the slip ring 115. Signals propagating around the transmission track 162 are capacitively coupled across the air gap 60 to the receiving probes 100 where they are amplified and transmitted to the communications receiver circuitry.

[0043] Whereas the transmission tracks 162 and receiving probe 100 are curved on a circular platter (as shown in Figures 1-4), in an alternative embodiment 200 shown in Figures 5 and 6, such transmission tracks and receiving probe are configured as straight, parallel tracks. Referring now to Figures 5 and 6, a second embodiment of an improved slip ring probe is generally designated 200. Except for its straight configuration, probe 200 is similar in construction and operation to curved probe 100.

[0044] As shown in Figure 5, the slip ring 215 has a longer transmission strip 260 of PCB material and a shorter differential conductive receiving probe 200. The transmission strip 260 and the receiving probe 200 are placed in close proximity and signals on the transmission strip are typically capacitively coupled across the air gap 60 to the receiving probe 200. Thus, the receiving probe 200 is placed above or adjacent to the transmission track 262 of the slip ring 215 as shown in Figure 5. Signals propagating down the transmission track 262 are capacitively coupled across the air gap 60 to the receiving probe 200 where they are amplified via amplifier 50 and transmitted to the communications receive circuitry.

[0045] As shown in FIG 6, the probe 200 is shown to broadly include a first conductive strip 210 and a second conductive strip 230. The first conductive strip 210 of the slip ring 200 includes a plurality of segments 219, 211A, 211B, 212A, 212B, 213A, and 213B, a plurality of resistors 221A, 221B, 222A, 222B, 223A, 223B, and 224A, a first end 215A, and a second end 215B. The plurality of segments 219, 211A, 211B, 212A, 212B, 213A, and 213B vary in length as shown in FIG 6 and as described with respect to the probe 100. Segments 211A and 211B, 212A and 212B, and 213A and 213B increase in length from central segment 219 to first end 215A and second end 215B, respectively, of first conductive strip 210.

[0046] Each of the first and second ends 215A and 215B of the first conductive strip 210 includes a first copper pad on a second copper pad that forms a small capacitance to ground in series with the adjacent resistors 224A and 224B, respectively, designed to attenuate frequencies of interest at specific locations. These pads are shown as squares having a width greater than the width of the plurality of segments 219, 211A, 211B, 212A, 212B, 213A, and 213B. However, other shapes and widths, including for the plurality of segments 219, 211A, 211B, 212A, 212B, 213A, and 213B, are believed to be suitable for the intended purpose as understood by one of ordinary skill in the art.

[0047] Furthermore, the plurality of resistors 221A, 221B, 222A, 222B, 223A, 223B, 224A, and 224B are configured to be positioned between adjacent segments of the plurality of segments 219, 211A, 211B, 212A, 212B, 213A, and 213B and the end pads 215A and 215B of the slip ring probe 200. The values ​​of the plurality of resistors of the first conductive strip 210 are selected to attenuate frequencies of interest at specific locations. This embodiment also includes two resistors between the central segment 219 and adjacent segments 211A and 211B of the plurality of segments, although only one resistor or more than two resistors are contemplated in this disclosure. Additionally, the length of the plurality of resistors varies depending on the size of adjacent segments of the plurality of segments of the first conductive strip 210.

[0048] The second conductive strip 220 of the slip ring 200 includes a plurality of segments 239, 231A, 231B, 232A, 232B, 233A, and 233B, a plurality of resistors 241A, 241B, 242A, 242B, 243A, 243B, and 244A, a first end 235A, and a second end 235B. The plurality of segments 239, 231A, 231B, 232A, 232B, 233A, and 233B vary in length as shown in FIG. 6 and as described with respect to the probe 100. Segments 231A and 231B, 232A and 232B, and 233A and 234B increase in length from a central segment 239 to first and second ends 235A and 235B, respectively, of second conductive strip 230.

[0049] The first end 235A and second end 235B of the first conductive strip 230 each include a first copper pad on a second copper pad that forms a small capacitance to ground in series with the adjacent resistors 244A and 244B, respectively, designed to attenuate frequencies of interest at specific locations. These pads are shown as squares having a width greater than the width of the plurality of segments 239, 231A, 231B, 232A, 232B, 233A, and 233B. However, other shapes and widths, including for the plurality of segments 239, 231A, 231B, 232A, 232B, 233A, and 233B, are believed to be suitable for the intended purpose as understood by one of ordinary skill in the art.

[0050] Additionally, the plurality of resistors 241A, 241B, 242A, 242B, 243A, 243B, 244A, and 244B are configured to be positioned between adjacent segments of the plurality of segments 239, 231A, 231B, 232A, 232B, 233A, and 233B and the end pads 235A and 235B of the slip ring probe 200. The values ​​of the plurality of resistors of the second conductive strip 230 are selected to attenuate frequencies of interest at specific locations. This embodiment also includes two resistors between the central segment 219 and adjacent segments 231A and 231B of the plurality of segments, although only one resistor or more than two resistors are contemplated in this disclosure. Additionally, the length of the plurality of resistors varies depending on the size of adjacent segments of the plurality of segments of the second conductive strip 230.

[0051] The outermost ends of the slip ring probe 200 (e.g., the first and second ends 215A and 215B of the first conductive strip 210 and the first and second ends 235A and 235B of the second conductive strip 230) have higher high frequency losses. The central portions of the slip ring probe 200, the central most segments 219 and 239, and the central vias 61 and 62 of the strips 210 and 230, respectively, have almost no loss at high frequencies. This keeps the highest frequencies fed to the amplifier 50 adjacent the central vias 61 and 62 of the segments 219 and 239 of the slip ring probe 200 (e.g., the multiple segments of the first conductive strip 210 and the multiple segments of the second conductive strip 230), which constrains the wavelength (frequency) to a length of conductive material that is short enough not to form a transmission line.

[0052] As the frequency of interest decreases, the wavelength increases and longer lengths of the first conductive strip 210 and second conductive strip 230 of the slip ring probe 200 are utilized. This larger signal acquisition area of ​​the slip ring probe 200 used at lower frequencies increases the coupling capacitance to the transmission trace 262. This is beneficial because higher frequencies couple well with less capacitance. To achieve the same coupling at lower frequencies, more capacitance is required (assuming the impedance is flat across the slip ring probe 200).

[0053] The first conductive strip 210 and the second conductive strip 230 of the slip ring probe 200 may be formed of PCB copper strips or any other conductive material suitable for the intended purpose and understood by one of ordinary skill in the art. In this embodiment, the multiple segments 219, 211A, 211B, 212A, 212B, 213A, and 213B of the first conductive strip 210 and the multiple segments 239, 231A, 231B, 232A, 232B, 233A, and 233B of the second conductive strip 230 are copper tabs whose lengths correspond to the frequency bandwidth and desired frequency response at that location of the slip ring probe 200 as shown in FIG. 6. FIG. 6 shows a loss tangent graph 250 having a loss tangent axis 251 and a probe length axis 252. 6 further illustrates various degraded frequency responses 253A, 253B, 254A, 254B, 255A, and 255B along the slip ring probe 200. For example, segments 211A and 231A of the first conductive strip 210 and the second conductive strip 230 correspond to loss tangent values ​​253A and 253B, respectively. Segments 212A and 232A of the first conductive strip 210 and the second conductive strip 230 correspond to loss tangent values ​​254A and 254B, respectively. Segments 213A and 233A of the first conductive strip 210 and the second conductive strip 230 correspond to loss tangent values ​​255A and 255B, respectively. Segments 219 and 239 of the first conductive strip 210 and the second conductive strip 230 correspond to loss tangent value 256.

[0054] As shown in FIG. 11A, at low frequencies, the slip ring probe 200 uses most of the length of the first conductive strip 210 and the second conductive strip 230 to transmit information to the amplifier 50. As shown in FIG. 11B, at higher frequencies, the central receiving segments 119 and 139 and other target-internal conductive segments, such as segments 211A, 211B, and 231A, 231B of the first conductive strip 210 and the second conductive strip 230 of the slip ring probe 200, transmit the signal to the amplifier 50. The higher frequencies toward the first ends 215A and 235A and the second ends 215B and 235B of the first conductive strip 210 and the second conductive strip 230 are dissipated and absorbed as heat. As such, there is no opportunity for propagation to the amplifier pick-up area 50.

[0055] 7, various eye diagrams of bit streams PRBS-7 and PRBS-31 are shown for the slip ring probe 100. The test results of the slip ring probe 100 correspond to the lower end frequency content in the frequency range from 500 Mbps to 10 Gbps.

[0056] There are locations across the slip ring transmission track 262 where the signal works well, but at other locations along the transmission track 262, the signal fails. These variations depend on the fundamental transmit frequency, and the resonant structure created as the receiving probe 200 causes the slip ring to change position relative to the transmission track 262, including locations where the track is discontinuous (e.g., across the air gap 60).

[0057] For example, to transmit signals such as HD video signals across a slip ring communication channel, a flat channel bandwidth of 33.7 MHz to 8910 MHz is utilized, all without any permutations to the amplitude and phase of the sine waves. These frequencies also correspond to waveform period lengths of approximately 25 mm to 7 meters (estimated at 75% of the speed of light for real PCB materials). These wavelengths are simultaneously transmitted to the receiving probe 200 via capacitive and / or inductive coupling.

[0058] As wavelengths get longer (frequency decreases), there are no transmission line effects (e.g., electromagnetic interference and noise) capacitively affecting energy into the receiving probe 200. This is because the lower frequency wavelengths are much greater than the length of the probe 200, and the probe 200 responds continuously along its length at these frequencies. These lower frequency signals are easily directed to the front end amplifier 50 without distortion. Low frequencies may affect the receiving probe 200 with periods longer than the length of the probe 200.

[0059] Higher frequencies are also simultaneously transmitted across the slip ring gap. As the frequency increases, the wavelength decreases, and at some point the receiving probe will transition from an otherwise capacitive structure to a transmission line coupler. For example, if the receiving probe had a length of 100 mm, the probe may begin to transition into the transmission line device at approximately a wavelength of 1000 mm (at 75% propagation efficiency) or 220 MHz. Higher frequencies may affect the receiving probe with periods shorter than the length of the probe.

[0060] Slip ring probes 100 and 200 utilize a unique continuous filtering mechanism embedded within the slip ring probe. Probes 100 and 200 exhibit improved probe response over a range of digital data rates and protocols by effectively transmitting only the correct component frequencies and waveform phase delays required to properly restore the digital waveform after a transition across the non-contacting air gap 60.

[0061] Probes 100 and 200 are very accurate and may be used with any set of frequency components to recover complex waveforms after transition across the air gap 60 that are much more complex than recovering simple binary digital waveforms (i.e., PAM-4). This topology requires a continuous change in loss tangent in the conductive material. The slip ring probe may be constructed by 3D printing methods using a variable doped material that increases the loss tangent along the length of the slip ring probe.

[0062] The slip ring probes 100 and 200 may be utilized with binary encoded digital waveforms. The slip ring probes 100 and 200 may also substantially reduce unwanted out-of-band noise that causes both timing skew and analog quantization errors. As a result, the slip ring probes 100 and 200 are adapted for accurate reconstruction of more complex communication waveforms across spatial gaps, including, but not limited to, PAM-4 and PAM-8 waveforms and their derivatives. The accuracy of the waveforms transmitted using the slip ring probes 100 and 200 may also be increased by using modulation other than binary, such as PAM-4 or QAM across the rotary interface, while increasing data transfer rates while using the same channel bandwidth. Additionally, the slip ring probes 100, 200 may utilize other digital waveform encoding schemes using alternative modulations, such as PSK, FSK, ASK, QAM, OOK, CPM, QPSK, FM, AM, and derivatives of these modulation techniques.

[0063] The slip ring probes 100, 200 also improve probe response over a range of digital data rates and protocols by effectively transmitting only the correct component frequencies and waveform phase delays needed to properly restore the digital waveform after a transition across the non-contact gap 60.

[0064] The slip ring probes 100, 200 also improve signal quality for long run length digital communications (e.g., SMPTE compliant video data streams) and 8b10b communications over rotary contactless interfaces, allowing for faster data transfer rates over the same bandwidth channel without the increased cost of requiring additional channel streams.

[0065] The slip ring probes 100, 200 may further be applied in rotary, linear, or stationary non-contact communication systems. The composition of the gap 60 between the signal source and the slip ring probes 100, 200 is typically air, but may be an air-like mixture, a vacuum, or a dielectric material of varying properties.

[0066] 8 and 9, a third embodiment of an improved slip ring probe is generally designated 300. As shown, the probe 300 has a curved configuration similar to the first embodiment probe 100 and may be used with a circular slip ring platter configuration of the slip ring 115. The probe 300 also has a pair of segmented conductive strips 310 and 330 with a first conductive strip 310 and a second conductive strip 330 each having a length corresponding to a desired low frequency domain of the receiver and configured to receive the signal 30 from the trace feed 362 of the transmitter 16 across the gap 60 of the rotary junction. The first conductive strip 310 and the second conductive strip 330 of the probe 300 are also not continuous, but instead are formed of a central segment 319 and 339 and a number of conductive segments or pads extending in either direction from the central segment, separately indicated at 311 and 331, respectively, such segments being separated by resistors therebetween, separately indicated at 314 and 334, respectively. However, the probe 300 differs from the probes 100 and 200 by the use of trailing resistor R and capacitor C elements, separately indicated at 321 and 341, coupled to each of the segments or pads 311 and 331, respectively, to reduce the frequency response for each of the segments 311 and 331 depending on the distance from or location relative to the central segments 319 and 339, respectively. Each of the conductive copper segments or pads 311 and 331 is therefore provided with a different frequency response, which frequency response decreases with distance from the probe center and pads 319 and 339, respectively. Each of the conductive segments 311 and 331 and resistors 314 and 334 have the same length. In this embodiment, resistors 314 and 334 are rotated 90 degrees to shorten the separation between the pads, and two smaller resistors are disposed between the central pads 319 and 339 and the immediately adjacent pads 311 and 334, respectively.

[0067] Thus, the slip ring probe 300 includes a first conductive strip 310 with alternating conductive copper segments or pads 311 and resistors 314 that form an RC element 321 along the strip that controls the pad frequency response, and a second conductive strip 330 with alternating copper segments or pads 331 and resistors 334 that form an RC element 341 along the strip that controls the pad frequency response to attenuate the highest frequencies received within the range of the slip ring probe 300 and prevent these frequencies from being transmitted to the central copper segments or pads 319 and 339 of the corresponding first conductive strip 310 and second conductive strip 330 of the slip ring probe 300. The R / C frequency filter elements 321 and 341 are attached to the underside of the respective segments or pads 311 and 331. In this embodiment, the capacitance of each of the capacitors C in the filter elements 321 and 341 increases with distance from or location relative to the central segments 319 and 339, such that the segments 311 and 331 directly adjacent to the central pads 319 and 339 have the lowest capacitance, and the capacitors C in the segments at the ends of the strips 310 and 330 have the highest capacitance. Thus, in this embodiment, the capacitance in the central segments 319 and 339 is zero, and such capacitance increases for each capacitor C for each segment 311 and 331 as they move away from the center of the probe, such segments becoming less and less responsive to frequency the further away from the center of the probe. Each of the conductive copper segments or pads 311 and 331 is thereby provided with a different frequency response, which decreases the further away from the probe center and the pads 319 and 339, respectively. In this embodiment, the capacitance of the capacitor C of each filter element 321 and 341 varies depending on the distance of the corresponding segment 311, 331 from the center of the probe, but the resistance of the corresponding resistor R of each filter element 321 and 341 may be the same.Strip 310 is shown having ten line resistors 314, line segments 311, and corresponding filter elements 321 on either side of a central segment and via 319. Strip 330 is shown having ten line resistors 334, line segments 331, and corresponding filter elements 341 on either side of a central segment and via 339. However, more or less line resistors, line segments, and filter elements may be utilized depending on the particular frequency range suitable for the intended purpose and understood by one of ordinary skill in the art.

[0068] The slip ring probe 300 is a graded frequency response probe that retains a segmented topology, but higher frequency components are attenuated in each of the conductive sections 311 and 331 by passive resistor R and capacitor C filters 321 and 341 (e.g., low pass filters), respectively, that effectively shunt the higher frequencies through resistive components to ground planes 322 and 342. The RC filters 321 and 341 are electrically coupled under the respective segments 311 and 331 of the corresponding first conductive strip 310 and second conductive strip 330. Thus, in this embodiment, the slip ring probe 300 includes a passive resistive-capacitive multi-pole low pass filter technique that runs the length of the probe 300, rather than an unterminated transmission line segment. In any event, the greater the distance from the center tab and center information tap 61 and 62, the more of the upper frequency region of the signal 30 that is attenuated.

[0069] The resistor R and capacitor C shown in the circuit representation of Figure 9 can be either discrete components, a mixture of discrete and PCB embedded components, or all PCB embedded components. Furthermore, increasing the number of components in the gradient frequency response (GFR) section results in a more concise representation of the original digital waveform, since it takes into account all possible harmonic frequencies contained in a given digital signaling progression without gaps. In a further embodiment, a GFR probe with even more smaller segments begins to behave as a typical continuous GFR probe, as shown in Figure 10.

[0070] 9 also shows that the frequency structure resonance range is from 2.6 GHz to 11 GHz, however, a smaller or larger frequency structure resonance range may be utilized by the slip ring probe as appropriate for the intended purpose and understood by one of ordinary skill in the art.

[0071] In this embodiment, slip ring probe 300 may have an overall length of approximately 2.30 inches. Each receiver pad 311 and 331 may be 0.11 inches long and 0.075 inches wide. The substrate of slip ring probe 300 may be an E R = ∼4, with a propagation velocity of approximately 50% of the speed of light (c). Resistors 314, 334 between pads 311, 331 are located vertically to minimize spacing between the pads. Filter components R, C may be located on each pad and may include discrete and / or embedded components. The values ​​of filter components R, C are selected to pass the highest frequencies while avoiding structural resonances.

[0072] FIG. 10 shows a typical loss tangent graph 40 having a loss tangent axis 251 and a probe length axis 252. FIG. 10 further shows a slip ring probe 400 with a frequency response 33 that continuously degrades along the length of the slip ring probe. The outermost ends of the slip ring probe towards the first ends 15A, 15B and second ends 35A, 35B of the slip ring probe have high frequency losses. The inner portion of the slip ring probe closest to the center tap or via 61, 62 has almost no loss at high frequencies. This allows higher frequencies to be fed to the amplifier 50 at the center tap 61, 62 of the slip ring probe and constrains the wavelength (frequency) of the portion of the conductive material 10, 30 of the slip ring probe to be short enough not to form a transmission line along the length of the slip ring probe. The smaller the conductive segments and the resistors between the conductive segments, the closer the loss tangent graph for the probe will be to the typical shown in FIG. 10.

[0073] It should be understood that certain features of the present disclosure that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0074] It is contemplated that many changes and modifications may be made in the present disclosure. Thus, while an improved probe configuration has been shown and described, and numerous alternatives have been discussed, those skilled in the art will readily appreciate that various further changes and modifications may be made without departing from the scope of the invention, as defined and differentiated by the following claims.

Claims

1. 1. A non-contact rotary joint for transmitting signals across a non-contact interface defined between two relatively movable members, comprising: a transmitter configured to transmit a signal over the contactless interface; a near field probe disposed in spaced relation to the transmitter and operatively arranged to receive the signal transmitted across the contactless interface, the near field probe having a signal acquisition area for receiving the signal transmitted across the contactless interface, the signal acquisition area comprising a segmented signal receiving strip having a length sized for a desired low frequency signal content of the signal and configured to receive a range of frequency signal content of the signal including the desired low frequency signal content of the signal, the segmented signal receiving strip comprising: a first signal receiving segment having a first frequency response; a second signal receiving segment having a second frequency response and electrically coupled to the first signal receiving segment; and a third signal receiving segment having a third frequency response and electrically coupled to the first signal receiving segment; a near field probe, the second frequency response of the second signal receiving segment being less than the first frequency response of the first signal receiving segment, and the third frequency response of the third signal receiving segment being less than the first frequency response of the first signal receiving segment; and receiving electronics operatively arranged to receive the range of frequency signal content received by the segmented signal receiving strip via the first signal receiving segment.

2. 2. The non-contact rotary joint of claim 1, wherein the first signal-receiving segment has a first length, the second signal-receiving segment has a second length that is greater than the first length, and the third signal-receiving segment has a third length that is greater than the first length.

3. 3. The non-contact rotary joint of claim 2, wherein the segmented signal-receiving strip comprises: a first dissipative element positioned between the first signal-receiving segment and the second signal-receiving segment and configured to isolate the first signal-receiving segment from the second signal-receiving segment; and a second dissipative element positioned between the first signal-receiving segment and the third signal-receiving segment and configured to isolate the first signal-receiving segment from the third signal-receiving segment.

4. 2. The non-contact rotary joint of claim 1, wherein the second signal-receiving segment comprises an electrically coupled resistor and capacitor arranged to provide a signal filter, and the third signal-receiving segment comprises an electrically coupled resistor and capacitor arranged to provide a signal filter.

5. 5. The non-contact rotary joint of claim 4, wherein the first signal-receiving segment has a first length, the second signal-receiving segment has a second length equal to the first length, and the third signal-receiving segment has a third length equal to the first length.

6. 5. The non-contact rotary joint of claim 4, wherein the segmented signal-receiving strip comprises: a first dissipative element positioned between the first signal-receiving segment and the second signal-receiving segment and configured to isolate the first signal-receiving segment from the second signal-receiving segment; and a second dissipative element positioned between the first signal-receiving segment and the third signal-receiving segment and configured to isolate the first signal-receiving segment from the third signal-receiving segment.

7. The non-contact rotary joint of claim 1 , wherein the first signal-receiving segment, the second signal-receiving segment, and the third signal-receiving segment each comprise copper.

8. 2. The non-contact rotary joint of claim 1, wherein the first frequency response of the first signal receiving segment corresponds to a first frequency sub-range of the range of the frequency signal content of the signal, the second frequency response of the second signal receiving segment corresponds to a second frequency sub-range of the range of the frequency signal content of the signal, and the first frequency sub-range of the range of the frequency signal content of the signal exceeds the second frequency sub-range of the range of the frequency signal content of the signal.

9. The non-contact rotary joint of claim 1 , wherein the signal transmitted by the transmitter across the non-contact interface is a high speed digital data output signal.

10. 2. The non-contact rotary junction of claim 1, wherein the transmitter comprises a signal source operatively arranged to provide a high speed digital data output signal, an impedance-controlled differential transmission line having a source gap and a termination gap, and a power splitter operatively arranged to receive the high speed digital data output signal from the signal source and to supply the high speed digital data output signal from the signal source to the source gap of the impedance-controlled differential transmission line, the near field probe being disposed in a spaced relationship with respect to the impedance-controlled differential transmission line and operatively arranged to receive the signal transmitted across the non-contact interface by the transmitter.

11. 2. The non-contact rotary joint of claim 1, wherein the segmented signal receiving strip comprises at least two further signal receiving segments, each of the further signal receiving segments having a frequency response and electrically coupled to the first signal receiving segment, the frequency response of each further signal receiving segment decreasing the further the further signal receiving segment is from the first signal receiving segment.

12. 12. The non-contact rotary joint of claim 11, comprising at least one dissipative element positioned between each of the second signal-receiving segment, the third signal-receiving segment, and the further signal-receiving segment, the dissipative element configured to isolate each of the signal-receiving segments from one another.

13. The non-contact rotary joint of claim 11 , wherein a length of each additional signal-receiving segment increases the farther the additional signal-receiving segment is from the first signal-receiving segment.

14. 12. The non-contact rotary joint of claim 11, wherein each of the second signal-receiving segment, the third signal-receiving segment, and the further signal-receiving segment comprises an electrically coupled resistor and capacitor arranged to provide a signal filter.

15. The non-contact rotary joint of claim 3 , wherein the first dissipative element and the second dissipative element each comprise a resistor.

16. The non-contact rotary junction of claim 1 , wherein the first signal-receiving segment comprises a center tap in communication with the receiving electronics.

17. 2. The non-contact rotary joint of claim 1, comprising a second segmented signal receiving strip oriented parallel to the segmented signal receiving strip, the second segmented signal receiving strip including a first signal receiving segment having a first frequency response, a second signal receiving segment having a second frequency response and electrically coupled to the first signal receiving segment, and a third signal receiving segment having a third frequency response and electrically coupled to the first signal receiving segment, the second frequency response of the second signal receiving segment being lower than the first frequency response of the first signal receiving segment and the third frequency response of the third signal receiving segment being lower than the first frequency response of the first signal receiving segment, and the receiver electronics are operatively arranged to receive signal content received by the second segmented signal receiving strip via the first signal receiving segment of the second segmented signal receiving strip.

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