Coil board of inductance type encoder
By designing a multi-layer PCB board and optimizing the coil layout, the problem of conductive vias affecting the radial length of the receiving coil was solved, thus improving the performance of the inductive encoder.
Patent Information
- Application Number
- CN202422632942.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2034-10-30
AI Technical Summary
The coil board of the existing inductive encoder has a conductive via, which reduces the radial length of the receiving coil, affecting the PCB manufacturing process and further affecting the encoder performance.
The design employs a multi-layer PCB board, with the excitation coils drawn concentrically on the same layer and overlapping in staggered layers, and electrically connected through conductive vias. The receiving coil has one less cycle of sine wave coil at the connection point of the excitation coil lead, and the corresponding part of the coil is also reduced at symmetrical positions to maintain the overall symmetry of the coil.
This ensures that the radial length of the receiving coil is maximized, avoids the influence of conductive vias, and ensures the stability and reliability of encoder performance.
Smart Images
Figure CN223485196U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of inductive encoders, and in particular to a coil board for an inductive encoder. Background Technology
[0002] Inductive encoders, also known as electromagnetic induction encoders, operate on the principle of electromagnetic induction. A current-carrying conductor generates a magnetic field, and the movement of the rotor affects this magnetic field, creating a voltage difference. This voltage difference is then converted into a mechanical signal. The basic principle is similar to that of a traditional rotary transformer, but instead of copper wire coil windings, it utilizes PCB technology to achieve dense coil windings.
[0003] The existing hollow coil board has a coil design where, after winding three turns on the outermost ring, conductive vias are placed above and below the receiving coil area. Since the receiving and excitation coils are drawn on the same two layers, the connection between the outermost excitation coil and the middle excitation coil must be achieved using conductive vias, with the connection traces routed through two additional layers. Figure 1 This will reduce the overall radial drawing length of the receiving coil due to the presence of two conductive vias. If the radial length of the receiving coil is already small or the number of cycles in one turn of the receiving coil is large, it will be detrimental to the drawing of the coil. This is because the two conductive vias reduce the radial length, and the conductive vias at the peak points of the receiving coil are too close to the traces or even overlap with the conductive vias. This makes it impossible for the PCB manufacturer to meet the PCB manufacturing requirements, thus affecting the encoder performance. Utility Model Content
[0004] To address the aforementioned issues, this invention provides a coil board for an inductive encoder. This addresses the problem in the prior art where the reduced radial length leads to a closer distance between conductive vias and wires, or where the distance between conductive vias may be very close when there are many peak points in the receiving coil cycle. This can result in failure to meet PCB manufacturing process requirements, thereby affecting encoder performance.
[0005] This utility model provides a coil board for an inductive encoder, comprising: a PCB board, a plurality of excitation coils and a receiving coil disposed on the PCB board, wherein the PCB board is a multilayer board; the plurality of excitation coils are drawn concentrically on the same layer and overlapped in staggered layers, the coils on the same layer are electrically connected by lead wires, and the coils on staggered layers are electrically connected by conductive vias; the receiving coil includes a plurality of sinusoidal waveform coils of multiple cycles; the receiving coil reduces the drawing of a sinusoidal waveform coil of one cycle at the connection of the lead wires of the excitation coils, and also reduces the drawing of a sinusoidal waveform coil of one cycle at a symmetrical position at the connection of the lead wires of the excitation coils.
[0006] Optionally, the PCB board is circular.
[0007] Optionally, the PCB board is selected from one of a 4-layer board, a 6-layer board, or an 8-layer board.
[0008] Optionally, the excitation coil includes three concentric multi-turn circular coils drawn on the first layer of the PCB board, namely coil A, coil B, and coil C, and three concentric multi-turn circular coils drawn on the second layer of the PCB board, namely coil a, coil b, and coil c. Coil A is drawn in a clockwise direction on the outermost ring of the first layer of the PCB board, and its lead-out end is connected to coil B. Coil B is drawn in a counterclockwise direction and its lead-out end is connected to coil C. Coil C is drawn in a clockwise direction and has a conductive via punched at its end to connect to coil c on the innermost ring of the second layer of the PCB board. The drawing direction of coils a, b, and c is opposite to that of coils A, B, and C, and their traces overlap.
[0009] Optionally, the multi-turn circular coil is a three-turn circular coil.
[0010] Optionally, the receiving coil includes a main code track coil and a vernier code track coil.
[0011] Optionally, both the main code track coil and the vernier code track coil include four multi-cycle sine wave coils.
[0012] Optionally, the sinusoidal waveform coil is drawn in staggered layers, with the layers changing every half cycle, and the conductive via of the receiving coil is located directly above the receiving coil during half a cycle.
[0013] Optionally, the receiving coil includes a 30-cycle sine wave coil.
[0014] Compared with existing technologies, the coil board of this inductive encoder maintains overall coil symmetry by removing a portion of the receiving coil at the conductive via and then removing the corresponding portion of the receiving coil at symmetrical positions. This maximizes the radial length of the receiving coil in the area without conductive vias, and the radial drawing area of the receiving coil is unaffected by conductive vias. This ensures the maximum radial length of the receiving coil on the coil board of an inductive encoder of the same specifications, guaranteeing encoder performance. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of a conventional coil plate in one embodiment of this utility model.
[0016] Figure 2 This is a schematic diagram of an embodiment of the present invention. Detailed Implementation
[0017] To address the issue that reduced radial length in existing technologies leads to a closer distance between conductive vias and wires, which can negatively impact encoder performance under certain conditions, this invention provides a coil board for an inductive encoder.
[0018] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.
[0019] This utility model provides a coil board for an inductive encoder, comprising: a PCB board, and a plurality of excitation coils and receiving coils disposed on the PCB board.
[0020] refer to Figure 2 The method for drawing three concentric excitation coils on the first layer of the 4-layer circular PCB board 1 is as follows: A coil 201, a three-turn circular coil, is drawn clockwise on the first layer of PCB board 1. The end lead of A coil 201 is connected to B coil 202. B coil 202 is drawn counterclockwise with three turns, and then the end lead is connected to C coil 203. C coil 203 is wound clockwise with three turns. In this way, the excitation coils on the first layer of PCB board 1 are completed. A conductive via is made at the end of C coil 203, and then the circuit is moved to the second layer of PCB board 1. The method of drawing three concentric excitation coils on the second layer of PCB 1 is opposite to and overlaps with the routing direction of the excitation coils drawn on the first layer of PCB 1. The beginning of coil c (which coincides with coil 203 in the figure) on the second layer of PCB 1 is connected to the conductive via at the end of coil 203. Coil c is drawn with three round turns counterclockwise, and the end lead is connected to coil b (which coincides with coil 202 in the figure). Coil b is drawn with three turns clockwise, and then the end lead is connected to coil a (which coincides with coil 201 in the figure). Coil a is drawn with three turns counterclockwise and then the end lead is connected to the corresponding pad. At this point, the entire excitation coil has been drawn.
[0021] The receiving coil includes a main code track coil 301 and a vernier code track coil 302. The main code track coil 301 and the vernier code track coil 302 are drawn in the same way. Each receiving coil is drawn from four sinusoidal coils. Half of the main code track coil 301 is drawn on the first layer of PCB board 1 within the induction area formed by coils A and B, and the other half is drawn on the second layer of PCB board 1 within the induction area formed by coils a and b. The drawing method is as follows: starting from the first sinusoidal waveform coil, draw a quarter cycle of traces on the first layer of PCB board 1 in a clockwise direction. Place conductive vias at the peaks of the sinusoidal waveform coil. Draw the next half cycle of traces on the second layer of PCB board 1. Place conductive vias at the troughs of the waveform and draw the remaining quarter cycle of traces on the first layer of PCB board 1. This completes the drawing of one cycle of the sine coil. Draw 30 cycles of sinusoidal waveform coils in the same way. The second sine wave coil is drawn starting on the second layer of PCB board 1, with its starting point coinciding with the starting point of the first sine wave coil but with a phase difference of 180°. Starting clockwise on the second layer of PCB board 1, a quarter-cycle coil is drawn. A conductive via is placed at the trough to the first layer to draw the next half-cycle coil, and another conductive via is placed at the crest to the second layer to draw the final quarter-cycle coil. This process is repeated for 30 cycles of sine wave coils. The third sine wave coil is drawn in the same way as the first, except that its starting point phase difference is 90°. The fourth sine wave coil is also drawn in the same way as the second, except that its starting point phase difference is 90°. The main code track coil 301 is not drawn with coils at the connection points between coils A and B, and between coils a and b, or at their opposite layer positions; instead, it is electrically connected via leads. At positions where one cycle of coil is symmetrically removed, connections are made using overlapping traces. Half of the vernier code track coil 302 is drawn on the first layer of PCB board 1 within the sensing area formed by coils B and C, and the other half is drawn on the second layer of PCB board 1 within the sensing area formed by coils b and c. The drawing method is exactly the same as that of the main code track coil 301.
[0022] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.
Claims
1. A coil board for an inductive encoder, comprising: A PCB board, wherein multiple excitation coils and receiving coils are disposed on the PCB board, wherein, The PCB board is a multilayer board; The multiple excitation coils are drawn concentrically on the same layer and overlapped in staggered layers. The coils on the same layer are electrically connected through lead wires, and the coils in staggered layers are electrically connected through conductive vias. The receiving coil includes a sinusoidal waveform coil with multiple cycles; The characteristic feature is that the drawing of a sinusoidal waveform coil with one cycle is reduced at the connection point of the excitation coil lead wire of the receiving coil, and the drawing of a sinusoidal waveform coil with one cycle is also reduced at a symmetrical position at the connection point of the excitation coil lead wire.
2. The coil board of an inductive encoder according to claim 1, characterized in that, The PCB board is circular.
3. The coil board of an inductive encoder according to claim 1, characterized in that, The PCB board is selected from one of the following: 4-layer board, 6-layer board, or 8-layer board.
4. The coil board of an inductive encoder according to claim 1, characterized in that, The excitation coils include three concentric multi-turn circular coils, namely coil A, coil B, and coil C, drawn on the first layer of the PCB board, and three concentric multi-turn circular coils, namely coil a, coil b, and coil c, drawn on the second layer of the PCB board. Coil A is drawn in a clockwise direction on the outermost ring of the first layer of the PCB board, and its lead-out end is connected to coil B. Coil B is drawn in a counterclockwise direction and its lead-out end is connected to coil C. Coil C is drawn in a clockwise direction and has a conductive via punched at its end to connect to coil c, which is the innermost ring of the second layer of the PCB board. The drawing directions of coils a, b, and c are opposite to those of coils A, B, and C, and their traces overlap.
5. The coil board of an inductive encoder according to claim 4, characterized in that, The multi-turn circular coil is a three-turn circular coil.
6. The coil board of an inductive encoder according to claim 1, characterized in that, The receiving coil includes a main code track coil and a vernier code track coil.
7. The coil board of an inductive encoder according to claim 6, characterized in that, Both the main code track coil and the vernier code track coil include four multi-cycle sine wave coils.
8. The coil board of an inductive encoder according to claim 7, characterized in that, The sinusoidal waveform coil is drawn in staggered layers, with each layer changing every half cycle. The conductive through-hole of the receiving coil is located directly above the receiving coil during half a cycle.
9. The coil board of an inductive encoder according to claim 1, characterized in that, The receiving coil comprises a 30-cycle sine wave coil.