Distributed adjustable capacitor for magnetic resonance imaging radio frequency coil
By using photolithographically etched capacitor connection conductors in the magnetic resonance imaging radio frequency coil, the problem of difficult distributed capacitance adjustment is solved, ensuring that the upper and lower conductors do not overlap. This enables precise adjustment of capacitance values and improves production efficiency.
Patent Information
- Application Number
- CN202422286542.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-19
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2034-09-19
AI Technical Summary
When using distributed capacitance, existing magnetic resonance imaging radio frequency coils have thin flexible insulating dielectric layers that are prone to short circuits between the upper and lower conductors. Inaccurate cutting leads to difficulties in adjustment and easy scrapping.
Design a distributed adjustable capacitor that uses photolithographic etching to form capacitor connection conductors, ensuring that the upper and lower conductors do not overlap in the vertical direction and that each effective capacitor unit has the same area. The capacitance value is adjusted by cutting the effective capacitor units.
It enables precise adjustment of capacitance value, avoids short circuit risk, simplifies the debugging process, and improves production efficiency.
Smart Images
Figure CN223513813U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a magnetic resonance imaging system technical field, specifically is a kind of for the distributed adjustable capacitor of magnetic resonance imaging radio frequency coil. BACKGROUND
[0002] Magnetic resonance imaging is an advanced human non-destructive imaging technology, widely used in medical imaging diagnosis of diseases in various parts of the human body. Magnetic resonance radio frequency coil is an important part of magnetic resonance imaging system, and its performance directly determines the quality of magnetic resonance image.
[0003] Traditional magnetic resonance radio frequency coil is formed by a plurality of lumped capacitors (generally ceramic capacitors) and a plurality of conductors arranged alternately and connected in sequence to form a loop. These capacitors and conductors are usually attached to an insulating medium layer (such as FR4 board or polyimide film). The inductance and capacitance of these conductors form a radio frequency resonance loop, which can most effectively detect the weak magnetic resonance radio frequency signals emitted by the human body when the resonance frequency is equal to the frequency of the magnetic resonance signal. The adjustment of the coil resonance frequency is realized by changing the number, position and capacitance value of the capacitors.
[0004] The distributed capacitance technology uses several segments of conductors which are not connected to each other to form distributed capacitance. The conductors form inductance on one hand and participate in forming distributed capacitance on the other hand. The resonant frequency can be adjusted by adjusting the length, width, relative position, etc. of the conductors. When the resonant frequency is equal to the magnetic resonance signal frequency, the magnetic resonance radio frequency signal can be effectively detected. The structure of the distributed capacitance is an upper layer of conductor, a lower layer of conductor and an insulating medium layer. The upper layer of conductor and the lower layer of conductor are located on the upper surface and the lower surface of the insulating medium. The overlapping area between the upper layer of conductor and the lower layer of conductor in the vertical direction determines the size of the distributed capacitance. The size of the capacitance can be adjusted by adjusting the overlapping area between the upper layer of conductor and the lower layer of conductor in the vertical direction of the capacitance, so as to change the resonant frequency of the coil. Generally, the upper layer of conductor and the lower layer of conductor of the distributed capacitance used in the magnetic resonance radio frequency coil are coincident in the overlapping area in the vertical direction of the capacitance, and the insulating medium layer in the middle is made of flexible material, such as polyimide film. In the actual production process, only the overlapping area of the conductors needs to be cut by scissors to change the resonant frequency of the coil, which is very convenient for production and debugging. However, because the flexible insulating medium layer is relatively thin, the scissors are very easy to cause the upper and lower layers of conductors to be connected together during the cutting process of the conductors, so as to form a short circuit point, resulting in failure of the entire magnetic resonance radio frequency coil. Moreover, because the thickness of the flexible insulating medium layer is very small, it is difficult to find the short circuit point when the short circuit fault occurs. Furthermore, the entire conductor of the general distributed capacitance is an integral whole and cannot be precisely cut to size. Only a small amount can be cut each time, and it is necessary to constantly try to reduce the capacitance value of the distributed capacitance to an appropriate size. Otherwise, if too much is cut, the capacitance value is less than the required value and there is no way to increase the capacitance value, so the entire coil may be scrapped.
[0005] Therefore, how to use the distributed capacitance on the magnetic resonance imaging radio frequency coil while avoiding the connection of the upper and lower layers of conductors of the capacitance to form a short circuit point when adjusting the capacitance value is a problem to be solved. SUMMARY
[0006] The utility model discloses a kind of distributed adjustable capacitances for magnetic resonance imaging radio frequency coil, the unit area of each effective capacitance is same, and with same size of capacitance value, so it is convenient to obtain required capacitance value by cutting once.
[0007] To achieve the above object, a kind of distributed adjustable capacitance for magnetic resonance imaging radio frequency coil is designed, including upper layer of conductor, lower layer of conductor, insulating medium layer, it is characterized in that: upper layer of conductor is located on the upper surface of insulating medium layer, lower layer of conductor is located on the lower surface of insulating medium layer;The overlapping part between upper layer of conductor and lower layer of conductor in vertical direction is effective capacitance, and the area of effective capacitance is effective capacitance value.
[0008] The upper layer conductor comprises an upper layer conductor of a main capacitor, an upper layer conductor of an effective capacitor, and an upper layer of a capacitor connecting conductor, one side of the upper layer conductor of the main capacitor is connected to the upper layer conductor of the effective capacitor, and a plurality of upper layers of the capacitor connecting conductor are uniformly arranged on the upper layer conductor of the effective capacitor.
[0009] The upper layer of the capacitor connecting conductor is formed by photoetching and etching.
[0010] The lower layer conductor comprises a lower layer conductor of a main capacitor, a lower layer conductor of an effective capacitor, and a lower layer of a capacitor connecting conductor, one side of the lower layer conductor of the main capacitor is connected to the lower layer conductor of the effective capacitor, and a plurality of lower layers of the capacitor connecting conductor are uniformly arranged on the lower layer conductor of the effective capacitor.
[0011] The lower layer of the capacitor connecting conductor is formed by photoetching and etching.
[0012] The upper layer conductor of the effective capacitor and the lower layer conductor of the effective capacitor are mutually overlapped to form an effective capacitor, and a gap is arranged between the upper layer of the capacitor connecting conductor and the lower layer of the capacitor connecting conductor.
[0013] The effective capacitor is one of a square, a circle, or other regular shapes.
[0014] Compared with the prior art, the utility model provides a kind of distributed adjustable capacitor for magnetic resonance imaging radio frequency coil, the unit area of effective capacitor of distributed adjustable capacitor is same, and it has same size of capacitance value, so when cutting distributed adjustable capacitor reduces capacitance value, just count corresponding number of effective capacitor and cut, without needing to reduce a little bit each time multiple times attempt, greatly save the debugging time of magnetic resonance radio frequency imaging radio frequency coil. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 It is the overall frame schematic diagram of the utility model.
[0016] Figure 2 It is the upper layer conductor structure schematic diagram in the utility model.
[0017] Figure 3 It is the lower layer conductor structure schematic diagram in the utility model.
[0018] Figure 4 It is the distributed adjustable capacitor structure schematic diagram of the utility model.
[0019] Figure 5 It is the cutting process schematic diagram of the distributed adjustable capacitor of the utility model.
[0020] Referring to Figures 1 to 41 is the upper conductor, 1-1 is the upper conductor of the main capacitor, 1-2 is the upper conductor of the effective capacitor, 1-3 is the upper layer of the capacitor connection conductor, 2 is the insulating dielectric layer, 3 is the lower conductor, 3-1 is the lower conductor of the main capacitor, 3-2 is the lower conductor of the effective capacitor, 3-3 is the lower layer of the capacitor connection conductor, and 4 is the effective capacitor. Detailed Implementation
[0021] The present invention will be further described below with reference to the accompanying drawings.
[0022] like Figure 1 As shown, the upper conductor 1 is located on the upper surface of the insulating dielectric layer 2, and the lower conductor 3 is located on the lower surface of the insulating dielectric layer 2; the overlapping portion between the upper conductor 1 and the lower conductor 3 in the vertical direction is the effective capacitance 4, and the area of the effective capacitance 4 is the effective capacitance value.
[0023] like Figure 2 As shown, the upper conductor 1 includes the upper conductor of the main capacitor, the upper conductor of the effective capacitor, and the upper layer of the capacitor connection conductor. One side of the upper conductor 1-1 of the main capacitor is connected to the upper conductor 1-2 of the effective capacitor. Several upper layers of capacitor connection conductors 1-3 are evenly distributed on the upper conductor 1-2 of the effective capacitor.
[0024] The upper layer 1-3 of the capacitor connection conductor is formed by photolithography etching.
[0025] like Figure 3 As shown, the lower conductor 3 includes the lower conductor of the main capacitor, the lower conductor of the effective capacitor, and the lower conductor of the capacitor connection conductor. One side of the lower conductor 3-1 of the main capacitor is connected to the lower conductor 3-2 of the effective capacitor. Several lower conductors 3-3 of the capacitor connection conductor are evenly distributed on the lower conductor 3-2 of the effective capacitor.
[0026] The lower layer 3-3 of the capacitor connection conductor is formed by photolithography etching.
[0027] like Figure 4 As shown, the upper conductor 1-2 of the effective capacitor and the lower conductor 3-2 of the effective capacitor overlap to form the effective capacitor 4, and there is a gap between the upper conductor 1-3 of the capacitor connection conductor and the lower conductor 3-3 of the capacitor connection conductor.
[0028] The effective capacitance 4 is a square, a circle, or another regular shape.
[0029] A method for adjusting the capacitance value of a distributed adjustable capacitor used in a magnetic resonance imaging radio frequency coil is described below:
[0030] S1, the upper conductor 1, the insulating dielectric layer 2, and the lower conductor 3 are stacked sequentially from top to bottom. The upper conductor 1-1 of the main capacitor of the upper conductor 1 and the lower conductor 3-1 of the main capacitor of the lower conductor 3 overlap to form the main capacitor; the upper conductor 1-2 of the effective capacitor of the upper conductor 1 and the lower conductor 3-3 of the capacitor connection conductor of the lower conductor 3 overlap to form the effective capacitor 4; the capacitance value of the entire distributed capacitor = main capacitor + effective capacitor × number of effective capacitors;
[0031] S2, adjust the number of effective capacitors according to the actual situation.
[0032] This invention adds a distributed adjustable capacitor next to a normal distributed capacitor (hereinafter referred to as the distributed main capacitor). The upper conductor 1 and lower conductor 3 of the distributed adjustable capacitor are both composed of many small regions (hereinafter referred to as effective capacitors 4) with the same area, and these regions overlap in the vertical direction of the capacitor. Each small region on the conductor layer is connected to the surrounding small regions by thin conductors (hereinafter referred to as capacitor connection conductors), and the upper and lower conductors used to connect the small regions are spaced a certain distance apart in the vertical direction of the capacitor, and do not overlap.
[0033] The magnetic resonance imaging radio frequency coil of this invention is very easy to debug. Simply cut some of the effective capacitor units (4 units) from the entire distributed capacitance to reduce the capacitance value, thereby changing the resonant frequency of the coil. Moreover, since the capacitor connecting conductors between the effective capacitor units of the upper and lower conductors are a certain distance apart in the horizontal direction of the capacitors, there is no risk of short circuit between the upper and lower conductors when they are cut.
[0034] like Figure 4 As shown, according to Figure 2 and Figure 3 The upper conductor 1 and lower conductor 3 are fabricated separately, and an insulating dielectric layer 2 is inserted between them to form the entire distributed adjustable capacitor. The actual operation involves photolithographic etching on the upper and lower sides of the flexible PCBA board with the upper and lower conductive layers. Figure 3 and Figure 2 The pattern is as follows. A distributed main capacitor is formed between the upper conductor 1-1 and the lower conductor 3-1 of the main capacitor, and a distributed adjustable capacitor is formed between the grid-like upper conductor 1 and the lower conductor 3. Figure 4 The distributed adjustable capacitor consists of 30 effective capacitors arranged in 5 rows and 6 columns.
[0035] like Figure 5 As shown, the method for adjusting the distributed capacitance of this utility model follows... Figure 5 Cut along the dotted line in the left-hand diagram to remove the three effective capacitors (4) on the left side of the first row, resulting in the following: Figure 5The distributed capacitance shown in the right side of the figure. The capacitance value of the whole distributed capacitance is changed from the capacitance value of the distributed main body capacitance plus the capacitance value of 30 effective capacitors 4 to the capacitance value of the distributed main body capacitance plus the capacitance value of 27 effective capacitors 4. Since the capacitance connection conductor upper layer 1-3 and the capacitance connection conductor lower layer 3-3 between the effective capacitor 4 units do not overlap in the vertical direction of the capacitance plane, there is no short circuit between the capacitance connection conductor upper layer 1-3 and the capacitance connection conductor lower layer 3-3 when the effective capacitor 4 is cut.
[0036] In summary, the magnetic resonance imaging radio frequency coil debugging of the utility model is very convenient, only need to cut some effective capacitor units from the whole distributed capacitance, can reduce the capacitance value, thereby change the resonant frequency of the coil. Moreover, the capacitance value of each effective capacitor unit is equal, because the resonant frequency can be adjusted very accurately. At the same time, since the capacitance connection conductor upper layer and the capacitance connection conductor lower layer between the upper and lower layer conductors have a certain distance in the vertical direction, so there is no risk of short circuit between the upper and lower layer conductors when cutting.
Claims
1. A distributed tunable capacitance for a magnetic resonance imaging radio frequency coil comprising an upper layer of conductors, a lower layer of conductors, an insulating dielectric layer, characterized in that: The upper layer conductor (1) is located on the upper surface of the insulating medium layer (2), and the lower layer conductor (3) is located on the lower surface of the insulating medium layer (2); the overlapping part between the upper layer conductor (1) and the lower layer conductor (3) in the vertical direction is an effective capacitor (4), and the area of the effective capacitor (4) is an effective capacitor value; The upper layer conductor (1) comprises an upper layer conductor of a main capacitor, an upper layer conductor of an effective capacitor, and an upper layer capacitor connection conductor; one side of the upper layer conductor of the main capacitor (1-1) is connected to the upper layer conductor of the effective capacitor (1-2), and a plurality of upper layer capacitor connection conductors (1-3) are uniformly arranged on the upper layer conductor of the effective capacitor (1-2). The lower layer conductor (3) comprises a lower layer conductor of a main capacitor, a lower layer conductor of an effective capacitor, and a lower layer capacitor connection conductor; one side of the lower layer conductor of the main capacitor (3-1) is connected to the lower layer conductor of the effective capacitor (3-2), and a plurality of lower layer capacitor connection conductors (3-3) are uniformly arranged on the lower layer conductor of the effective capacitor (3-2).
2. A distributed tunable capacitance for a magnetic resonance imaging radio frequency coil according to claim 1, characterized in that: The upper layer capacitor connection conductor (1-3) is formed by photoetching and etching.
3. A distributed tunable capacitance for a magnetic resonance imaging radio frequency coil according to claim 1, wherein: The lower layer capacitor connection conductor (3-3) is formed by photoetching and etching.
4. A distributed tunable capacitance for a magnetic resonance imaging radio frequency coil according to claim 1, wherein: The upper layer conductor of the effective capacitor (1-2) and the lower layer conductor of the effective capacitor (3-2) are mutually overlapped to form the effective capacitor (4), and a gap is arranged between the upper layer capacitor connection conductor (1-3) and the lower layer capacitor connection conductor (3-3).
5. A distributed tunable capacitance for a magnetic resonance imaging radio frequency coil according to claim 1 or 4, characterized in that: The effective capacitor (4) is one of a square and a circle.