Slip ring impedance matching structure

Abstract

The utility model relates to the technical field of impedance matching, in particular to a slip ring impedance matching structure, which comprises a slip ring and a cable. The slip ring impedance matching structure comprises a slip ring, the slip ring is provided with a differential signal ring, the differential signal ring is used for transmitting high-speed signals, the differential signal ring adopts a parallel plate type cavity, the slip ring is further provided with a conducting ring and an insulating sheet, and the conducting ring and the insulating sheet are both matched with the parallel plate type cavity. The method is simple in calculation, low in manufacturing cost, suitable for impedance calculation of various high-speed signals and capable of meeting the requirement for stable transmission of the various high-speed signals.

Description

Technical Field

[0001] The utility model relates to the technical field of impedance matching, in particular to a slip ring impedance matching structure. Background Art

[0002] Impedance matching means that the internal resistance of the signal source is equal to the characteristic impedance of the connected transmission line and the phase is the same, or the characteristic impedance of the transmission line is equal to the load impedance and the phase is the same. The input or output end of the transmission line is in impedance matching state, referred to as impedance matching. Otherwise, it is called impedance mismatch, sometimes directly called matching or mismatch. Impedance matching is divided into two cases: low frequency and high frequency. In low-frequency circuits, we generally do not consider the matching problem of transmission lines, but only consider the situation between the signal source and the load. Because the wavelength of low-frequency signals is very long relative to the transmission line, the transmission line can be regarded as a "short line" and reflection can be ignored (because the line is short, even if it is reflected back, it is still the same as the original signal). In high-frequency circuits, we must also consider the problem of reflection. When the frequency of the signal is very high, the wavelength of the signal is very short. When the wavelength is short enough to be comparable to the length of the transmission line, the reflected signal superimposed on the original signal will change the shape of the original signal. If the characteristic impedance of the transmission line is not equal to the load impedance (that is, mismatched), reflection will occur at the load end. The characteristic impedance (also called characteristic impedance) of a transmission line is determined by the structure and material of the transmission line, and has nothing to do with the length of the transmission line, the amplitude and frequency of the signal, etc. When we design a high-speed signal slip ring, it is equivalent to cutting a high-speed wire, adding a slip ring structure in the middle, and then connecting the wire. Therefore, the characteristic impedance of the slip ring should be as consistent as possible with the characteristic impedance of the wire to ensure stable signal transmission, which involves the impedance matching of the slip ring. The purpose of impedance matching of the slip ring is to make the characteristic impedance of the slip ring itself as consistent as possible with the characteristic impedance of the transmission line. At present, the design schemes of high-speed signal slip rings include: direct output, no impedance matching design, using wire with amplifier to improve stability; or using smaller slip rings for design.

[0003] The existing slip ring impedance matching structure adopts a direct line-out method without impedance matching design, and uses a conductor with an amplifier to improve stability, but the production cost will increase; the design adopts a smaller slip ring, which limits the size of the slip ring. Therefore, in view of the above situation, it is urgent to develop a slip ring impedance matching structure to overcome the shortcomings in current practical applications. Utility Model Content

[0004] The purpose of the utility model is to provide a slip ring impedance matching structure to solve the problems raised in the above background technology.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A slip ring impedance matching structure, the slip ring impedance matching structure comprising a slip ring and a cable;

[0007] The slip ring is provided with a differential signal ring, the differential signal ring is used to transmit high-speed signals, and the differential signal ring adopts a parallel plate cavity;

[0008] The slip ring is also provided with a conductive ring 1 and an insulating sheet 2, and both the conductive ring 1 and the insulating sheet 2 are arranged in coordination with the parallel plate cavity.

[0009] As a further solution of the utility model: the characteristic impedance of the slip ring is twice the differential impedance of the cable.

[0010] As a further solution of the utility model: the slip ring adopts the structure of LPM-30B and is used for transmitting high-speed signals.

[0011] As a further solution of the utility model: the conductive ring 1 adopts a copper ring structure, the inner diameter of the copper ring is 5.3 mm, the outer diameter is 5.8 mm, and the width is 0.5 mm.

[0012] As a further solution of the utility model: the characteristic impedance value of the slip ring is 200±10%Ω.

[0013] As a further solution of the utility model: there are two empty rings between the two rings of the differential signal ring.

[0014] Compared with the prior art, the beneficial effects of the utility model are:

[0015] 1. The slip ring impedance matching design of the present application is simple to calculate and has a low manufacturing cost.

[0016] 2. The slip ring impedance matching design method of the present application can be applied to impedance calculation of various high-speed signals to meet the stable transmission of various high-speed signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic cross-sectional structure diagram of the parallel plate cavity model of the utility model.

[0018] Figure 2 It is a schematic diagram of the mathematical model of the slip ring in the utility model.

[0019] Figure 3 This is a wiring diagram of the slip ring impedance matching structure in the utility model.

[0020] Figure 4 It is a schematic diagram of the settlement results of the impedance calculation software in the utility model.

[0021] Figure 5This is a schematic diagram of the coupling structure of the brush and the copper ring in the utility model.

[0022] In the figure: 1-conductive ring, 2-insulating sheet. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] The specific implementation of the present utility model is described in detail below in conjunction with specific embodiments.

[0025] See also Figure 1-Figure 4 , an embodiment of the utility model provides a slip ring impedance matching structure, the slip ring impedance matching structure includes a slip ring and a cable;

[0026] The slip ring is provided with a differential signal ring for transmitting high-speed signals, and the differential signal ring adopts a parallel plate cavity. The slip ring is also provided with a conductive ring 1 and an insulating sheet 2, and the conductive ring 1 and the insulating sheet 2 are both arranged in coordination with the parallel plate cavity.

[0027] In one embodiment of the present invention, the characteristic impedance of the slip ring is twice the differential impedance of the cable.

[0028] In one embodiment of the utility model, the slip ring adopts the structure of LPM-30B for transmitting high-speed signals. The conductive ring 1 adopts the structure of a copper ring, the inner diameter of the copper ring is 5.3mm, the outer diameter is 5.8mm, and the width is 0.5mm. The characteristic impedance value of the slip ring is 200±10%Ω.

[0029] In one embodiment of the present invention, there are two empty rings between the two rings of the differential signal ring.

[0030] The theoretical basis of slip ring design is transmission line theory. The goal of slip ring design is to make the slip ring consistent with the characteristics of the transmission line as much as possible during rotation. Therefore, the characteristic impedance of the slip ring is as close as possible to the differential impedance of the cable itself, such as USB3.0 (90Ω) and HDMI / DP (100Ω). It is mainly designed based on the characteristics of the wire. The differential signal ring must use a parallel plate cavity to maintain consistency with the balanced twisted pair. Figure 1 As shown, the characteristic impedance of the parallel plate cavity is closely related to the size of the conductive ring 1 of the slip ring, and the material and size of the insulating sheet 2. By changing the relevant parameters of the parallel plate cavity, a slip ring with corresponding impedance can be designed.

[0031] like Figure 2 As shown, since the slip ring is rotating, it is impossible to make the characteristic impedance Z1 of the slip ring (Z1 is different when it rotates to different positions) match the transmission line Z0 when the slip ring rotates to any position, that is, it is equal to 100 ohms. Mismatch will cause reflection, and reflection will bring reflection loss, causing signal attenuation. Taking into account the different positions of a circle, Z1 is designed to be 2Z0, so that when the input and output cables of the slip ring are 180° relative to each other, theoretically complete matching is achieved. In other words, when the characteristic impedance of the slip ring is designed to be twice the differential impedance of the cable, the impedance matching effect is best and the transmission performance of the slip ring is best. Therefore, when the impedance is within the range of 200±10%Ω, the transmission is more stable.

[0032] The LPM-30B structure is used to transmit high-speed signals: by checking the size of the copper ring and the insulating sheet, the inner diameter of the copper ring is 5.3mm, the outer diameter is 5.8mm, and the width of the copper ring is 0.5mm. By changing the distance between the rings, the impedance value is close to 200±10%Ω; after many proofing tests, the two rings of the differential signal are empty, and the matching effect is the best. The impedance calculation software such as Figure 4 As shown, the impedance is 193.8, which is within the range of 200±10%Ω. The slip ring of the present application adopts a non-standard impedance matching design, which can stably transmit DisplayPort (or HDMI) video signals and USB3.0 signals, etc., and solves the problem of simultaneous transmission of multiple high-speed signals without interference.

[0033] like Figure 1 As shown in the figure, the core shaft of the slip ring rotor is a series of parallel copper rings, which are isolated by insulating medium, and the signal lines are welded on the inside of the copper rings. The stator brush part of the slip ring is composed of a series of brushes corresponding to the copper rings. Each group of brushes has two contact areas with the copper rings, such as Figure 5 As shown in the figure, it can be called two-point coupling. This coupling method not only reduces the transmission loss of the signal, but also improves the redundancy of the signal transmission.

[0034] In addition, the slip ring uses the slip ring lead to connect with the video cable. Correspondingly, the same line connection is defined. Each group of high-speed signal lines is shielded separately with aluminum foil wrapped on the outside. After all the lines are connected, they are shielded with aluminum foil and shielding net on the outside, and then wrapped with outer cover. The shielding quality of the external wiring part is directly related to the quality of the slip ring transmission signal. It is necessary to refer to the cable structure for shielding.

[0035] It should be noted that, in the present invention, unless otherwise clearly specified and limited, the terms "slide", "rotate", "fix", "have" and the like should be understood in a broad sense, for example, it can be a welding connection, a bolt connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A slip ring impedance matching structure, characterized in that: The slip ring impedance matching structure includes a slip ring and a cable; The slip ring is provided with a differential signal ring, the differential signal ring is used to transmit high-speed signals, and the differential signal ring adopts a parallel plate cavity; The slip ring is also provided with a conductive ring and an insulating sheet, and the conductive ring and the insulating sheet are both arranged in coordination with the parallel plate cavity.

2. The slip ring impedance matching structure according to claim 1, characterized in that: The characteristic impedance of the slip ring is twice the differential impedance of the cable.

3. The slip ring impedance matching structure according to claim 1 or 2, characterized in that: The slip ring adopts the structure of LPM-30B and is used for transmitting high-speed signals.

4. The slip ring impedance matching structure according to claim 3, characterized in that: The conductive ring adopts a copper ring structure, and the inner diameter of the copper ring is 5.3 mm, the outer diameter is 5.8 mm, and the width is 0.5 mm.

5. The slip ring impedance matching structure according to claim 4, characterized in that: The characteristic impedance value of the slip ring is 200±10%Ω.

6. The slip ring impedance matching structure according to claim 1, characterized in that: There are two empty spaces between the two differential signal rings.

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