CN114156714B - Manufacturing method of capacitive coupling slip ring - Google Patents
Manufacturing method of capacitive coupling slip ring Download PDFInfo
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Abstract
The invention relates to a manufacturing method of a capacitive coupling slip ring, belongs to the technical field of X-ray Computed Tomography (CT) technology, and solves the problems that the prior slip ring increases the communication rate of the whole system by widening the width of a rotating disc, so that the equipment volume is increased and the cost is high. The manufacturing method of the capacitive coupling slip ring comprises the following steps: step 1: selecting a tray body; step 2: manufacturing a first groove along one circle of the inner surface of the tray body; step 3: fixing a transmitting end data processing unit on a disc body; the transmitting antenna is fixed in the first groove. The invention realizes multi-channel data transmission.
Description
Technical Field
The invention relates to the technical field of X-ray Computed Tomography (CT) technology, in particular to a manufacturing method of a capacitive coupling slip ring.
Background
Because of its own unique advantages, X-ray Computed Tomography (CT) technology is highly appreciated and widely used in the field of security inspection.
Capacitively coupled slip rings are one of the key components of CT for power and data transfer between the rotor and stator ends of CT.
At present, the common non-contact conductive slip ring mainly adopts two data transmission modes of wireless capacitive coupling transmission and optical transmission between rotating bodies.
The capacitive coupling slip ring realizes signal transmission through capacitive coupling between a flexible antenna surrounding the outer edge of the rotating disc and a receiving antenna at the fixed end. Compared with an optical transmission electric slip ring, the capacitive coupling slip ring has the advantages of small volume, light weight, small occupied space and low cost; but there are also electromagnetic radiation generated and susceptible to electromagnetic interference; the distance change between the moving coil and the static coil can influence the data acquisition, so that the data transmission rate is difficult to meet the requirement.
The capacitive coupling slip ring transmitting antenna and the receiving antenna are both printed circuit boards. The characteristics of the printed circuit board material and the connection mode of the plug-in units have the problem of signal integrity effect along with the improvement of the frequency of the transmission signal; in combination with the wireless capacitive coupling transmission principle, the highest signal transmission rate is limited, and the signal transmission rate cannot be infinitely improved. The highest signal transmission rate of the single-channel transmitting antenna in the current market is 10Gbps. As the amount of data of transmission information increases, a higher requirement is also put on the transmission rate and the bit error rate.
The prior art generally increases the communication rate of the entire system by increasing the number of communication channels while securing a transmission rate of 10Gbps per channel by increasing the width of the excessively wide rotating disk. But an increase in the width of the rotating disk increases the volume of the apparatus and increases the cost.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a method for manufacturing a capacitive coupling slip ring, so as to solve the problems of increased equipment volume and high cost caused by increasing the communication rate of the whole system by widening the width of a rotating disc in the prior slip ring.
The aim of the invention is mainly realized by the following technical scheme:
the invention provides a manufacturing method of a capacitive coupling slip ring, which comprises the following steps:
step 1: selecting a tray body;
step 2: manufacturing a first groove along one circle of the inner surface of the tray body;
step 3: fixing a transmitting end data processing unit on a disc body; the transmitting antenna is fixed in the first groove.
Based on the further improvement of the manufacturing method, the step 1 and the step 2 further comprise a step 1a: and a second groove is formed along the periphery of the outer surface of the tray body.
Based on the further improvement of the manufacturing method, the step 3 further comprises the step 4: the transmitting antenna is fixed in the second groove.
Based on the further improvement of the manufacturing method, the step 3 of fixing the transmitting antenna in the first groove specifically comprises the following steps: and 2 transmitting antennas are respectively connected with two paths of the data processing unit at the transmitting end, and the 2 transmitting antennas are enclosed into a circle.
Based on the further improvement of the manufacturing method, in the step 2, 2 first grooves are manufactured along the circumference of the inner surface of the disc body, and the space between the 2 first grooves is 1-2 times the width of the transmitting antenna.
Based on the further improvement of the manufacturing method, the distance between the 2 first grooves is 1-2 times of the width of the transmitting antenna.
Based on the further improvement of the manufacturing method, the inner diameter of the disc body is 1050mm, the outer diameter of the disc body is 1300mm, and the thickness of the disc body is 45mm.
Based on the further improvement of the manufacturing method, the width of the first groove manufactured in the step 2 is 23mm, and the depth is 3mm.
Based on the further improvement of the manufacturing method, in the step 3, the transmitting antenna is adhered in the first groove through an adhesive.
Based on the further improvement of the manufacturing method, in the step 1a, 2 second grooves are manufactured along the circumference of the outer surface of the disc body, and the interval between the 2 second grooves is 1-2 times of the width of the transmitting antenna.
Compared with the prior art, the invention has at least one of the following beneficial effects:
(1) The transmitting antenna of the prior art is disposed on the outer surface of the rotating disk, and in order to increase the communication rate of the entire system, the prior art generally increases the communication rate of the entire system by increasing the number of communication channels while securing a transmission rate of 10Gbps per channel by widening the width of the rotating disk. But an increase in the width of the rotating disk increases the volume of the apparatus and increases the cost. According to the invention, the transmitting antennas are arranged on the inner surface and the outer surface of the rotating disk at the same time, so that the number of communication channels can be increased without increasing the width of the rotating disk, and the communication rate of the whole system can be improved.
(2) In order to prevent signal interference between different transmitting antennas at the same side, the distance between the different transmitting antennas at the same side is not less than three times (i.e. 3W) of the width W of the transmitting antennas in the prior art, the scheme of the embedded receiving antennas is adopted, namely the depth of a groove used for placing the transmitting antennas on the rotating disk is greater than the thickness of the transmitting antennas, and after the transmitting antennas are placed in the groove, the height difference exists between the upper surface of the transmitting antennas and the outer surface of the rotating disk. The arrangement can effectively reduce the radiation field of the transmitted signals, so that the interference between different transceiver modules can be reduced even under the condition of reducing the space between different groups of transmitting antennas, and the utilization rate of the electric slip ring disc body is effectively improved under the condition of ensuring normal signal communication.
(3) In the prior art, a PCB is generally used as a capacitive coupling antenna, and because the PCB is made of brittle materials, the capacitive coupling antenna made of the PCB is easy to break in the bending process, and the length of the capacitive coupling antenna made of the produced PCB is limited and is generally not more than 2.5m. Therefore, when the capacitive coupling type antenna made of the two PCB boards is wound on the rotating disk, a distance exists between the signal output ends and the signal input ends of the two antennas due to the limited length, so that the signal transmission efficiency is reduced. Because the two antennas are easy to break in the bending process, the two antennas are likely to lose the information transmission function in the using process. According to the invention, the capacitive coupling type antenna is manufactured by using polyethylene or tetrafluoroethylene as a base material, so that the capacitive coupling type antenna has enough flexibility, the length of the generated antenna can reach more than 2m, and the situation that the antenna is broken in the bending process can be ensured, thereby improving the signal transmission efficiency.
(4) The CT detection device of the present invention includes a rotating disc, on which a capacitive coupling antenna (transmitting antenna) is typically required to be wound and rotated 360 degrees with the rotating disc. Therefore, the transmitting antenna and the transmitting communication module are connected in the form of a connector, so that the capacitive coupling type antenna rotates 360 degrees along with the rotating disc.
In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.
FIG. 1 is a schematic diagram of a capacitive coupling slip ring according to an embodiment of the present invention;
FIG. 2 is a partial cross-sectional view of a rotating disk according to an embodiment of the present invention;
FIG. 3 is a graph of the spacing between adjacent transmit antennas versus antenna width in the prior art;
fig. 4 is a partial cross-sectional view of a rotating disc with a transmitting antenna embedded therein according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a CT detection apparatus according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a two-layer circuit board according to an embodiment of the present invention;
FIG. 7 is a CT block diagram;
FIG. 8 is a block diagram of a method for manufacturing a capacitively coupled slip ring according to an embodiment of the present invention;
fig. 9 is a graph of the correspondence between the number of CT layers and the data bandwidth.
Reference numerals:
1-rotating the disc; 2-a transmitting antenna; 3-a first groove; 4-a second groove; a 5-receiving unit; 6-an insert; 7-a first metal copper foil; 8-a substrate; 9-a second metal copper foil; a 10-ray source; an 11-CT gantry; a 30-CT detector; 40-the object to be inspected; 50-conveyor belt; 60-conveyor belt motor; 70-a motion control computer; 80-slip ring motor; 90-data processing computer.
Detailed Description
The following detailed description of preferred embodiments of the invention is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the invention, are used to explain the principles of the invention and are not intended to limit the scope of the invention.
Example 1
In one embodiment of the invention, a capacitively coupled slip ring is disclosed comprising a rotating disc 1, a transmitting unit and a receiving unit.
As shown in fig. 1, the transmitting unit includes a transmitting antenna 2 and a transmitting-end data processing unit, the transmitting-end data processing unit includes a transmitting circuit board and a data line, and the transmitting antenna 2 and the data line are both connected to the transmitting circuit board. The transmitting antenna 2 is illustratively connected to the transmitting circuit board by means of a connector. The transmitting circuit board is fixed on the rotating disk.
The transmitting antenna used in the present invention has a flat or stripe shape.
The rotary disk is hollow large-aperture annular in the interior, the outer surface of the rotary disk is provided with a first groove 3 which is circumferentially arranged, the shape of the first groove 3 is matched with that of the transmitting antenna 2, and the transmitting antenna 2 is arranged in the first groove 3.
It should be noted that, according to the different diameters of the rotating disc, the number of the transmitting antennas in the first groove 3 may be 1, or may be a complete circle formed by a plurality of antennas. Specifically, the circuit board has two paths, and adjacent antennas are respectively connected with one path of the circuit board. The receiving unit comprises a receiving circuit board and a data line, and the data line is connected with the receiving circuit board.
The receiving unit 5 comprises a receiving-end data processing unit and a receiving antenna, which can be integrated on a printed circuit or can be connected in the form of a plug-in.
The receiving unit comprises a first receiving unit and a second receiving unit, wherein the first receiving unit is arranged near the outer surface of the rotating disc and is 1.5-5mm away from the transmitting antenna in the first groove.
In a possible embodiment, the inner surface of the rotating disc 1 is also provided with circumferentially arranged grooves (second grooves 4), as shown in fig. 2. The shape of the second recess 4 matches the shape of the transmitting antenna, which is placed in the second recess.
The transmitting antenna 2 in this embodiment is fixed in the groove, and for example, the transmitting antenna may be fixed in the groove by means of adhesion.
The second receiving unit is arranged near the inner surface of the rotating disc and is 1.5-5mm away from the transmitting antenna in the second groove.
The number of the first grooves 3 and the second grooves 4 is at least one. For example, 1 first groove, 1 second groove; or 1 first groove and 2 second grooves; 2 first grooves and 1 second groove; alternatively, 2 first grooves, 2 second grooves, as shown in fig. 2. The second groove may or may not correspond to the first groove.
The transmission unit and the receiving unit are realized by a capacitive coupling principle, namely electric field coupling between the receiving and transmitting antennas. If the distances between the different groups of receiving and transmitting antennas are too close, crosstalk situations among different receiving and transmitting modules can occur, so that abnormal communication situations can occur. Therefore, in order to prevent signal interference between different transmitting antennas on the same side, the distance D between the different transmitting antennas on the same side is not less than three times the width W of the transmitting antennas (i.e., 3W) and the thickness H of the medium between the transmitting antennas on different sides is not less than three times the width of the transmitting antennas as shown in fig. 3 (for convenience of expression, the transmitting antennas are shown to protrude from the outer surface of the rotating disk).
However, due to the limitation of space, the distance between different transceiver modules cannot be infinitely increased. Thus, in one possible embodiment of the present invention, a scheme of embedding the receiving antenna is adopted, i.e. the depth of the groove is not the same as the thickness of the transmitting antenna, but the depth of the groove is larger than the thickness of the transmitting antenna, as shown in fig. 4. In this way, after the transmitting antenna is placed in the recess, there is a height difference between the upper surface of the transmitting antenna and the outer surface of the rotating disc, i.e. the upper surface of the transmitting antenna is not flush with the outer surface of the rotating disc, but is lower than the outer surface of the rotating disc.
Specifically, the thickness of the antenna was 2mm and the depth of the groove was 3mm. The surface of the transmitting antenna is thus at a distance of 1mm from the side of the rotating disc. The arrangement can effectively reduce the radiation field of the transmitted signals, so that the interference between different transceiver modules can be reduced even under the condition of reducing the space between different groups of transmitting antennas, and the utilization rate of the electric slip ring disc body is effectively improved under the condition of ensuring normal signal communication.
According to experimental study, the invention discovers that the space between the transmitting antennas at the same side does not need to be 3 times (namely 3W) of the width of the transmitting antennas by adopting the embedded structure, and normal communication can be ensured only by 1-2 times of the width of the transmitting antennas.
Example two
Another embodiment of the present invention discloses a CT detection device, a capacitively coupled slip ring is one of the key components of CT for power and data transfer between the rotor and stator ends of CT.
With the progress of CT technology, the amount of data acquired by the detector increases, and the required data transmission bandwidth can be estimated according to equation 6, so as to obtain the following correspondence between the CT layer number and the data bandwidth. Equation 6:
s is the data transmission bandwidth; p is the number of multi-layer spiral CT DAS channels; n is the number of single-layer spiral CT detectors; m is the number of data bits sampled by each detector once; v is slip ring rotation speed; f is the sampling frequency.
The corresponding relation between the CT layer number and the data bandwidth is shown in figure 9.
According to the corresponding relation between the CT layers and the data bandwidth, the data transmission bandwidth of the 16-layer spiral CT needs to be 1.25Gbps, the data transmission bandwidth of the 64-layer spiral CT needs to be 5Gbps, the data transmission bandwidth of the 256-layer spiral CT needs to be 20Gbps, and the data bandwidth requirement of the 640-layer spiral CT needs to be 50Gbps. Single channel capacitive coupling transmission has not been satisfactory, and therefore the present invention provides a scheme for multi-channel transmission.
The CT detection apparatus of the present embodiment includes a radiation source 10, a rotating disk 1 and a CT detector 30, a conveyor belt 50, a data processing unit 90, a conveyor belt motor 60, a slip ring motor 80, and a motion control computer 70, as shown in fig. 5. The radiation source 10 is fixed on the rotary disk 1, the conveyor belt 50 passes through the hollow large aperture of the rotary disk 1, the detected object 40 is placed on the conveyor belt 50, and the CT detector 30 is also fixed on the rotary disk 1. The conveyor belt 50 is connected with the conveyor belt motor 60, the rotating disk 1 is connected with the slip ring motor 80, the conveyor belt motor 60 and the slip ring motor 80 are connected with the motion control computer 70, and the CT detector 30 is connected with the data processing unit 90.
The specific working mode is that when the detected object 40 is inspected, the rotating disk 1 rotates to drive the ray source 10 and the CT detector 30 to rotate 360 degrees so as to obtain images of the detected object 40 from a plurality of angles. Wherein the transmitting antennas wound circumferentially along the outer and inner surfaces of the rotating disk 1 are used to transmit the image obtained by the CT detector 30 to the data processing unit 90.
Example III
Existing transmit antennas are typically capacitively coupled antennas, which are typically made of printed circuit boards (Printed circuit boards, PCB). The PCB board is cut into a certain size by taking the insulating board as a base material, at least one conductive pattern is attached on the insulating board, and holes (such as element holes, fastening holes, metallized holes and the like) are distributed on the insulating board for replacing the chassis of the electronic components of the traditional device and realizing the interconnection between the electronic components. Is called a "printed" circuit board because it is fabricated using electronic printing techniques. The current PCB mainly comprises a circuit and a drawing, a dielectric layer, holes, solder resist ink, silk screen printing and surface treatment.
The capacitive coupling antenna made of the PCB has the advantages that: because the PCB pattern has repeatability (reproducibility) and consistency, the errors of wiring and assembly are greatly reduced, and the maintenance, debugging and inspection time of the antenna is saved. The design is standardized, the product is small, the weight is light, and the antenna has the characteristics of replaceability, convenience, precision, miniaturization, and the like.
The capacitor coupling antenna made of PCB has the defects of high cost, long period and incapability of producing due to process limitation for the circuit board with the requirements of overlength and flexibility
The present embodiment provides a capacitive coupling antenna for CT detection, as shown in fig. 6, including: an interposer 6, a first metal copper foil 7, a base material 8, and a second metal copper foil 9. The first metal copper foil 7 is composed of an upper copper foil wire and a lower copper foil wire, and the upper copper foil wire and the lower copper foil wire are differential wires. The interposer 6, upper copper foil trace and lower copper foil trace are disposed on one side of the substrate 8. On the other face of the base material 8, a second metal copper foil 9 is provided, the second metal copper foil 9 also includes the interposer 6, upper copper foil wiring and lower copper foil wiring, and the upper copper foil wiring and the lower copper foil wiring are differential wires. Wherein, the material of the base material is polyethylene or polytetrafluoroethylene so as to ensure that the length of the circuit board can be more than 2m. Thus, the two capacitive coupling antennas arranged on the rotating disk can realize that the signal output end and the signal input end are mutually contacted so as to reduce the attenuation of signals in the transmission process. Meanwhile, the flexibility of the polyethylene and the polytetrafluoroethylene can ensure that the capacitive coupling antenna is not easy to break when being bent, and the signal transmission efficiency is further improved.
In the embodiment of the invention, one side of the plug-in unit 6 is connected with the communication module, and the other side is connected with the upper and lower copper foil wires.
In an embodiment of the present invention, the process parameters of the circuit include: the thickness of the base material, the thickness of the upper copper foil wiring, the width of the upper copper foil wiring, the thickness of the lower copper foil wiring and the width of the lower copper foil wiring.
Specifically, the thickness of the substrate is; 0.7mm-1.0mm; the dielectric constant of the substrate is 2.2-2.8:
the thickness of the upper copper foil wire is as follows: 0.1mm-0.2mm; the width of the upper copper foil wiring copper foil is as follows: 4mm-7mm.
The thickness of the lower copper foil wiring is as follows: 0.1mm-0.2mm; the width of the lower copper foil routing copper foil is as follows: 3cm-5cm.
The parameters are determined based on the selection of the substrate. From a qualitative point of view, polyethylene (PE) is a thermoplastic resin made by polymerizing ethylene, typically a soft and tough polymer. The PE has higher volume resistivity, smaller dielectric constant and dielectric loss factor and is hardly affected by frequency.
Polytetrafluoroethylene has excellent chemical stability, corrosion resistance, sealing property, high lubricating non-tackiness, electrical insulation and good aging resistance. The polytetrafluoroethylene has high temperature resistance, the working temperature can reach 250 ℃, the polytetrafluoroethylene has low temperature resistance, and the polytetrafluoroethylene has good mechanical toughness at low temperature, and can keep 5 percent of elongation even if the temperature is reduced to minus 196 ℃.
The invention adopts polyethylene and/or polytetrafluoroethylene as the matrix, can increase the flexibility of the circuit board, greatly increases the length of the circuit board, and ensures that the circuit board is not easy to break in a winding state.
Based on the impedance matching of the dielectric thickness, the conductor width (upper and lower copper foil wiring widths) and the metal thickness (namely the upper and lower copper foil wiring thicknesses), the invention carries out the impedance matching design of the flexible circuit on the dielectric thickness, the conductor width (upper and lower copper foil wiring widths) and the metal thickness (namely the upper and lower copper foil wiring thicknesses) when polyethylene and/or polytetrafluoroethylene are adopted as matrixes. The characteristic impedance calculation formula of the single conductor of the strip line is shown as formula 1, and the differential impedance calculation is shown as formula 2.
Equation 1:
equation 2:
Z 0 is the characteristic impedance (in ohm), H represents the thickness of the medium (in mil) between the signal line and the plane, W represents the line width (in mil), T Cu Represents the thickness of the metal (in mil), ε r Indicating the dielectric constant. Z is Z Diff Is the differential impedance (in ohms), S represents the edge spacing of the traces (in mils), and H represents the total dielectric thickness (in mils) between the planes.
The signal propagates along the transmission line with a corresponding instantaneous impedance at each step along its path. The impedance of the different transmission lines is different, so that when a signal is transmitted from one transmission line to the other, the instantaneous impedance of the signal changes, and then a part of the signal is reflected, and the other part of the signal is distorted and continuously transmitted. The greater the impedance difference, the greater the reflected signal quantity. The abrupt impedance change has a great influence on the distortion of the transmission signal, and it directly causes the degradation of the rising edge of the reception signal. In order to obtain the optimal signal quality, the design of the invention enables the antenna to be 2m or more so as to avoid signal distortion caused by different instantaneous impedance.
When in direct current, the current is uniformly distributed in the signal wire, and the resistance is shown in formula 3:
equation 3:
r represents the resistance of the transmission line (in omega), ρ represents the bulk resistivity of the wire (in omega in), len represents the wire length (in), w represents the wire width (in), and t represents the thickness of the wire (in).
At high frequencies, the cross-sectional thickness of the current flowing in the copper wire is approximately equal to the skin depth δ, as shown in equation 4:
equation 4:
where δ represents skin depth (in μm) and f represents sine wave frequency (in GHz). Because of the skin effect, if a current flows through only the lower half of the wire, the resistance of the wire is approximated as equation 5:
equation 5:
where R represents the line resistance (in Ω), ρ represents the bulk resistivity of the wire (in Ω·in), len represents the line length (in), w represents the line width (in), and δ represents the skin depth (in).
It can be seen that the equivalent resistance of the transmission line increases with the frequency of the transmission signal, i.e. the loss of the signal increases with the frequency. Therefore, the accurate impedance is designed, and the attenuation of the transmission medium to the signal can be effectively reduced.
According to the invention, polyethylene and/or polytetrafluoroethylene are selected as the base material of the circuit board, and meanwhile, the capacitive coupling antenna manufactured by the circuit board is optimized in terms of material performance and connection mode, so that the stability and definition of images are ensured.
Once the CT detector is deactivated, the image of the object 40 to be detected is necessarily interrupted. The present application proposes a method of image stitching, i.e. to join together the images of the detected object 40 before and after the stop of the belt, so as to avoid image interruption. It should be noted that, the capacitive coupling antenna of the invention can ensure the stability and definition of the image, and provides a technical basis for the method.
Specifically, the CT detection apparatus further includes: an encoder. The encoder is arranged on the driving belt and moves along with the driving belt. The encoder is used for acquiring movement data of the transmission belt and transmitting the corresponding relation to the data processing unit, and the movement data comprises: the moving speed and the moving time of the driving belt.
The data processing unit is used for determining that the transmission belt is in a belt stop state according to an externally input stop instruction; and splicing images of the detected object before and after stopping the tape according to the X-ray signals, the moving data and the preset rewinding time transmitted by the capacitive coupling antenna.
Further, the CT detector 30 acquires X-ray signals corresponding to the first image of the detected object, and transmits the X-ray signal image corresponding to the first image to the data processing unit 90 through the capacitive coupling antenna. The data processing unit 90 determines the first image from the corresponding X-ray signals. The encoder collects movement data of the belt and transmits the movement data to the data processing unit 90, the movement data comprising: the moving speed and the moving time of the driving belt. The data processing unit 90 determines whether the detected object 40 stops moving according to a stop instruction input from the outside. Upon determining that the detected object 40 stops moving, the data processing unit 90 determines whether the detected object 40 exists within a preset detection range based on the first image.
When the detected object 40 exists in the preset detection range, the data processing unit 90 controls the driving belt to rewind through the encoder, so that the detected object 40 leaves the preset detection area, controls the detected object 40 to enter the preset detection area, and acquires a second image of the detected object 40 through the CT detector 30 and the capacitive coupling antenna. Finally, the data processing unit 90 performs stitching on the first image and the second image to obtain a complete image of the detected object 40.
When the detected object 40 is not present within the preset detection range, the data processing unit 90 controls the belt to move in the direction approaching the radiation source 10 through the encoder.
Example IV
The embodiment of the invention provides a manufacturing method of a capacitive coupling type antenna, which is used for preparing a transmitting antenna of the first embodiment and comprises the following steps:
and 1, selecting a base material.
In an embodiment of the present invention, polyethylene and/or polytetrafluoroethylene are used as the substrate.
And 2, determining the thickness and width of the upper copper foil wire, the thickness and width of the lower copper foil wire and the thickness of the substrate according to the impedance matching property of the flexible circuit.
And 3, attaching the upper copper foil wiring and the lower copper foil wiring on the base material to obtain the circuit board.
And 4, attaching insulating films on the top surface and the ground of the circuit board to obtain the capacitive coupling antenna.
The following describes the technical solution of the present application in detail with reference to examples. The circuit board is a flexible circuit board, the flexible circuit board is a two-layer flexible circuit board with the length of x width of x height of 2000mm of x 30mm of x 1mm, and the design is applied to the communication field and is an antenna for transmitting signals. The antenna needs to transmit signals at a rate of 2.5GBbps and a length of 2 meters, and is bent at a certain angle to be matched with equipment. The flexible circuit board is provided with a pair of differential lines, the differential impedance is 85 ohms, and the top layer wiring is copper foil with the width of 6mm and the thickness of 0.1mm. The distance between the two wires is 1mm. The intermediate substrate is polyethylene with a thickness of 0.8mm. The bottom layer is copper foil with the width of 3cm and the thickness of 0.1mm.
Step 1, selecting polyethylene as a base material.
Polyethylene (PE) is a thermoplastic resin made by polymerizing ethylene and is typically a soft and tough polymer. The PE has higher volume resistivity, smaller dielectric constant and dielectric loss factor and is hardly affected by frequency.
And 2, determining parameters.
The choice of materials is not only impedance but also sufficient choiceConvenience of the material. 3M industrial tape 9508W was selected for manufacturing process difficulties and material procurement considerations. The industrial adhesive tape is a double-sided adhesive tape, and can be used for conveniently pasting a signal transmission line. The industrial adhesive tape has high foam density of 90kg/m 3 The thickness was 0.8mm. The width of the copper foil conductor for transmitting signals is 6mm, and the thickness is 0.1mm.
And 3, assembling the antenna.
The metal copper foil is precisely adhered to an industrial adhesive tape as a base material. The required signal transmission line is obtained. Then, insulating films are adhered to the top and bottom ends of the circuit.
And 4, testing.
And testing the characteristic impedance and the S parameter of the processed flexible circuit by using a network analyzer, and determining the quality of the flexible circuit. The flexible circuit (length of 2 m) can reach high-frequency signal with transmission rate of 2.5Gbps, namely the measured signal attenuation is reduced by less than 3dB.
The length of the mature manufacturing process of the current high-frequency printed circuit board can reach 1.2 meters, and the high-frequency printed circuit board has no flexibility. The cost of producing a printed circuit with a length of 1.2 meters is about 2000 yuan. For the production requirement of longer high-speed printed circuits, a new production line and a new process are developed together with manufacturers, and the defects of high cost and uncontrollable quality exist.
The design method of the high-speed flexible circuit provided by the invention can only ensure the accuracy of pasting the transmission conductor. The length of the flexible circuit board can be realized by measuring and cutting by using a measuring ruler, so that the flexible circuit board can be formulated according to the product requirement. The used dielectric materials and transmission conductor materials are common materials in the market, have very low cost and are easy to purchase. The cost of the single capacitive coupling antenna produced by the method is lower than 50 yuan.
Example five
In another embodiment of the present invention, a method for manufacturing a capacitive coupling slip ring is disclosed, as shown in fig. 8, for manufacturing a capacitive coupling slip ring according to the first embodiment, including the following steps:
first, the rotating disk is designed and machined.
And determining the number of the transmitting and receiving devices according to the size of the data quantity required to be transmitted. According to the actual situation, a rotating disk with a corresponding size is designed.
The rotating disk designed in this embodiment has an inner diameter of 1050mm, an outer diameter of 1300mm and a thickness of 45mm. The rotating disk is made of metal, for example, steel.
And a first groove is formed along the periphery of the outer surface of the rotary disk, wherein the width of the first groove is 23mm, and the depth of the first groove is 3mm.
And a second groove is formed along the periphery of the inner surface of the rotary disk, the width of the second groove is 23mm, and the depth of the second groove is 3mm. The position of the second groove corresponds to the position of the first groove.
Second, a transmitting unit of the outer surface of the rotary disk (group 2n-1, n=1, 2,3 … …) is mounted.
The transmitting end data processing unit is arranged on the rotating disc through the positioning hole; the transmitting antenna is fixed in the first groove on the outer surface of the rotating disc in a sticking mode.
Third, a transmitting unit of the inner surface of the rotating disk (group 2n, n=1, 2,3 … …) is mounted.
The transmitting end data processing unit is arranged on the rotating disc through the positioning hole; the transmitting antenna is fixed in the second groove on the outer surface of the rotating disc in a sticking mode.
Example six
In another embodiment of the present invention, a method for installing a capacitive coupling slip ring is disclosed, for installing the capacitive coupling slip ring of the first embodiment, including the steps of:
first, a rotating disk (rotor end) is mounted on the CT gantry 11 as shown in fig. 7.
Second, receiving units (first receiving units) of the outer surface of the rotating disk (group 2n-1, n=1, 2,3 … …) are mounted.
The first receiving unit (i.e., the stator end) is fixed to the CT gantry. The first receiving unit comprises a receiving end data processing module and a receiving antenna, and the two parts can be integrated on a printed circuit or connected in a plug-in mode. The stator end is located outside the rotor end (rotating disk). The receiving antenna is perfectly aligned with the transmitting antenna, spaced 3mm apart.
Third, a receiving unit (second receiving unit) of the inner surface of the rotating disk (group 2n, n=1, 2,3 … …) is mounted.
The second receiving unit (i.e. the stator end) is fixed to the CT gantry. The second receiving unit comprises a receiving end data processing module and a receiving antenna, and the two parts can be integrated on a printed circuit or connected in a plug-in mode. The stator end is located inside the rotor end (rotating disk). The receiving antenna is perfectly aligned with the transmitting antenna, spaced 3mm apart.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (7)
1. The manufacturing method of the capacitive coupling slip ring is characterized by comprising the following steps of:
step 1: selecting a rotating disk;
step 2: manufacturing a first groove along the periphery of the inner surface of the rotating disc;
step 3: fixing a transmitting end data processing unit on a rotating disk; the transmitting antenna is fixed in the first groove;
step 1a is further included between the step 1 and the step 2: manufacturing a second groove along the periphery of the outer surface of the rotating disc;
step 3 is followed by step 4: fixing the transmitting antenna in the second groove;
the step 3 of fixing the transmitting antenna in the first groove specifically includes the following steps: 2 transmitting antennas are respectively connected with two paths of a transmitting end data processing unit, and the 2 transmitting antennas are enclosed into a circle;
the depth of the groove used for placing the transmitting antenna on the rotating disk is larger than the thickness of the transmitting antenna, and after the transmitting antenna is placed in the groove, a height difference exists between the upper surface of the transmitting antenna and the outer surface of the rotating disk.
2. The method of manufacturing a capacitively coupled slip ring according to claim 1, wherein in said step 2, 2 first grooves are formed along a circumference of an inner surface of the rotating disk.
3. The method of manufacturing a capacitively coupled slip ring of claim 2, wherein a spacing between 2 first grooves is 1-2 times a width of the transmitting antenna.
4. The method of manufacturing a capacitively coupled slip ring of claim 1, wherein said rotating disk has an inner diameter of 1050mm, an outer diameter of 1300mm and a thickness of 45mm.
5. The method of manufacturing a capacitively coupled slip ring of claim 1, wherein said first recess formed in step 2 has a width of 23mm and a depth of 3mm.
6. The method of manufacturing a capacitively coupled slip ring of claim 1, wherein in step 3, the transmitting antenna is adhered to the first recess by an adhesive.
7. The method of manufacturing a capacitively coupled slip ring according to claim 1, wherein in step 1a, 2 second grooves are formed along a circumference of an outer surface of the rotating disk, and a space between the 2 second grooves is 1-2 times a width of the transmitting antenna.
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| CN115178973A (en) * | 2022-07-19 | 2022-10-14 | 深圳市华盛电气技术有限公司 | CT medical slip ring casting process |
| CN115207743B (en) * | 2022-08-03 | 2023-05-19 | 浙江恩碧技创新科技有限公司 | Production process of large-diameter conductive slip ring |
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| CN108258556A (en) * | 2018-04-18 | 2018-07-06 | 嘉兴恩碧技电气有限公司 | A kind of spliced CT slip rings |
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| US5224138A (en) * | 1991-01-28 | 1993-06-29 | Kabushiki Kaisha Toshiba | Slip ring device |
| CN108258556A (en) * | 2018-04-18 | 2018-07-06 | 嘉兴恩碧技电气有限公司 | A kind of spliced CT slip rings |
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