Electronic compasses

Abstract

The utility model discloses an electronic compass which comprises an operation handle, a main body, a pin foot and a line pen foot. The main body comprises a shell, a display screen, a sensor and a controller; a shaft pin is arranged on the shell; the pin comprises a first foot part and a first coupling part; a needle part is mounted at the front end of the first foot part, a first coupling hole is formed in the first coupling part, and a gear is arranged at the tail end of the first coupling part; the line pen foot comprises a second foot part and a second coupling part, a line drawing pen is installed at the front end of the second foot part, a second coupling hole is formed in the second coupling part, and an arc-shaped tooth part is arranged at the tail of the second coupling part; the shaft pin penetrates through the first coupling hole and the second coupling hole, and the gear is meshed with the arc-shaped tooth part. The positioning support is installed in the shell, the positioning support enables the center line between the two compass feet to be basically consistent with the operating handle, it is guaranteed that the operating handle of the electronic compass is perpendicular to a target face through the positioning support, and therefore a stable structural foundation is provided for high-precision drawing.

Description

Technical Field

[0001] This utility model relates to a compass, and more particularly to an electronic compass, which can automatically measure the distance between the needle and the pencil lead and display the measured distance on the display screen to facilitate drawing circles. Background Technology

[0002] A traditional compass mainly consists of two legs connected by a pivot. One leg ends in a steel needle used to fix the center point; the other leg can be used to attach drawing tools such as pencil leads. To use it, first fix the needle to the paper to determine the center, then adjust the distance between the two legs according to the desired radius. Hold the handle at the top of the compass and rotate the leg with the drawing tool around the needle to draw a circle. However, traditional compasses have drawbacks such as limited drawing accuracy and inconvenient operation.

[0003] Patent document 1 (CN105513437A) discloses an electronic compass system that interacts with an electronic terminal by arranging electromagnetic points at key points on the compass. The system includes an electromagnetic compass and an electronic terminal. The electronic terminal senses the compass's position information through an electromagnetic induction coil substrate and converts it into point-to-point coordinates in the system's coordinate system, thereby digitizing the compass operation. This system can not only draw electronic arcs but also display the distance between the compass's two legs and the arc angle in real time, overcoming the shortcomings of traditional compasses and making it suitable for electronic teaching and homework scenarios. The specific and detailed structure of this electronic compass system is not disclosed.

[0004] Patent document 2 (CN109109522A) designs an electric compass for primary school teaching scenarios. This compass uses a miniature servo motor and a threaded rod to control the sliding of the traction bearing seat on the guide rod, thereby achieving rapid adjustment of the compass radius. Its clamping box design can quickly grab chalk or other drawing tools, improving drawing efficiency. This utility model solves the problem of the inconvenience of manually adjusting the radius of traditional compasses, and is particularly suitable for scenarios where compasses are used frequently in primary school teaching. However, its complex structure, large size, and high cost make it unsuitable for widespread adoption among students. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide an electronic compass that is low in cost and has high reliability.

[0006] The core technical concept of this solution lies in ensuring that the operating handle of the electronic compass is perpendicular to the target surface through a positioning bracket, thereby providing a stable structural foundation for high-precision drawing. Based on this, the precise meshing of the gear assembly further ensures the synchronous movement and precise adjustment of the compass feet. The combined effect of these two aspects significantly improves the drawing accuracy and stability of the compass.

[0007] The technical solution of this utility model is: an electronic compass, including an operating handle, a main body, needles and thread pen feet; the operating handle is located at the upper end of the main body, and the needles and thread pen feet are rotatably mounted on the lower side of the main body to form two compass feet;

[0008] The main body includes a housing, a display screen, a sensor, and a controller; the display screen is mounted on the housing, and the sensor and controller are connected and installed inside the housing; the sensor detects the angle between the pin and the pen tip, and the distance between the pin and the pen tip is obtained through processing by the controller and displayed on the display screen;

[0009] The housing is provided with a shaft pin; the pin includes a first foot and a first shaft connection; the front end of the first foot is equipped with a pin, the first shaft connection is provided with a first shaft connection hole, and the tail end of the first shaft connection is provided with a gear.

[0010] The pen tip includes a second foot and a second shaft connection. A drawing pen is installed at the front end of the second foot. A second shaft connection hole is provided on the second shaft connection. An arc-shaped toothed part is provided at the tail end of the second shaft connection. The shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively. The gear meshes with the arc-shaped toothed part.

[0011] A positioning bracket is installed inside the housing to keep the center line between the two compass feet substantially aligned with the operating handle.

[0012] A further preferred embodiment of this utility model is as follows: the positioning bracket includes a bracket body, the upper end of which is provided with two prongs; the lower end of the operating handle is provided with two holes, and the prongs can be slidably inserted into the holes;

[0013] The lower end of the bracket body is provided with a vertical positioning hole and a horizontal positioning hole; the shaft pin is located in the vertical positioning hole;

[0014] At least one positioning pin is provided on the first or second shaft connection portion, and the positioning pin is located in the transverse positioning hole.

[0015] A further preferred embodiment of this utility model is as follows: the vertical positioning hole and the horizontal positioning hole are arranged in a cross shape, a first positioning pin is provided on the first shaft connection part, a second positioning pin is provided on the second shaft connection part, and the first positioning pin and the second positioning pin are respectively located at both ends of the horizontal positioning hole.

[0016] A further preferred embodiment of this invention is that the sensor is a magnetic sensor or a rotary encoder.

[0017] A further preferred embodiment of this utility model is that the housing includes a front shell and a rear shell, which are connected to each other.

[0018] A further preferred embodiment of this utility model is as follows: the gear has an outer diameter of 3-8mm and has 10-30 teeth; the movement trajectory of the arc-shaped tooth is arc-shaped, and the radius of the circle corresponding to the arc-shaped trajectory is 15-35mm, and the arc-shaped tooth has 75-105 teeth.

[0019] Another subject: An electronic compass, comprising an operating handle, a body, needles, and a pen tip; the operating handle is located at the upper end of the body, and the needles and pen tip are rotatably mounted on the lower side of the body to form two compass legs;

[0020] The main body includes a housing and an intelligent measuring device installed inside the housing, which can display the included angle between the pin and the pen pin on a display screen outside the housing;

[0021] The housing is provided with a shaft pin, and the pin and the thread pen are both provided with shaft connection holes. The pin and the thread pen are connected to the shaft pin together through the shaft connection holes.

[0022] A positioning bracket is installed inside the housing. The positioning bracket includes a bracket body, and the upper end of the bracket body is provided with two prongs. The lower end of the operating handle is provided with two holes, and the prongs are inserted into the holes.

[0023] The connecting handle at the lower end of the bracket body is provided with a vertical positioning hole and a horizontal positioning hole; a positioning pin is provided on one side of the shaft connection hole of the needle or the shaft connection hole of the thread pen.

[0024] The shaft pin is located in the vertical positioning hole, and the positioning pin is located in the horizontal positioning hole, so that the center line between the operating handle and the two compass feet is on the same straight line;

[0025] The pin and the pen tip are connected by a gear assembly to achieve synchronous rotation.

[0026] A further preferred embodiment of this utility model is as follows: the pin includes a first foot and a first shaft connection; a pin is installed at the front end of the first foot, and a first shaft connection hole is provided on the first shaft connection;

[0027] The pen foot includes a second foot and a second shaft connection. A drawing pen is installed at the front end of the second foot. A second shaft connection hole is provided on the second shaft connection. The shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively.

[0028] The gear assembly includes a gear at the tail end of the first shaft connection portion and an arc-shaped tooth portion at the tail end of the second shaft connection portion; the gear meshes with the arc-shaped tooth portion;

[0029] The gear has an outer diameter of 3-8mm and 10-30 teeth; the movement trajectory of the arc-shaped tooth is arc-shaped, and the radius of the circle corresponding to the arc trajectory is 15-35mm, and the arc-shaped tooth has 75-105 teeth.

[0030] A further preferred embodiment of this utility model is as follows: the pin includes a first foot and a first shaft connection, the pen foot includes a second foot and a second shaft connection; the shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively;

[0031] The vertical positioning hole and the horizontal positioning hole are arranged in a cross shape. The first shaft connection part is provided with a first positioning pin, and the second shaft connection part is provided with a second positioning pin. The first positioning pin and the second positioning pin are respectively located at both ends of the horizontal positioning hole.

[0032] A further preferred embodiment of this utility model is: the intelligent measuring device includes a sensor and a controller installed inside the housing, wherein the sensor is a magnetic sensor or a rotary encoder;

[0033] The sensor detects the angle between the needle and the pen tip, and the distance between the needle and the pen tip is obtained through the controller and displayed on the screen.

[0034] The housing includes a front shell and a rear shell, which are connected to each other.

[0035] Compared with existing technologies, the advantages of this invention are as follows: In the use of traditional compasses, the perpendicularity of the operating handle to the target surface is a fundamental condition for accurate drawing. However, traditional compasses often lack an effective structure to ensure the stability and consistency of this condition, causing the compass legs to wobble or shift during actual use, thus affecting the accuracy and stability of the drawing. To solve this problem, this technical solution introduces a positioning bracket, cleverly ensuring that the center line between the two compass legs remains basically aligned with the operating handle, thereby guaranteeing that the operating handle can stably remain perpendicular to the target surface during use.

[0036] The positioning bracket's structural design includes a bracket body with a pin at the upper end that engages with a hole at the lower end of the operating handle to form a stable connection. The lower end has vertical and horizontal positioning holes for precisely constraining the movement of the compass feet. A pivot pin passes through the vertical positioning hole to ensure the stability of the compass feet's rotation center, while positioning pins are located at both ends of the horizontal positioning holes to further constrain the compass feet's movement trajectory. This design effectively prevents the compass feet from wobbling or shifting during rotation, ensuring the operating handle remains perpendicular to the target surface, significantly improving the stability and accuracy of drawing.

[0037] Furthermore, the synergistic effect of the positioning bracket and gear assembly is key to achieving the high precision and stability of the electronic compass. The positioning bracket, through its unique structural design, ensures that the center line between the two compass legs remains aligned with the operating handle, thereby guaranteeing that the operating handle remains stably perpendicular to the target surface during use and significantly improving the overall stability of the compass. The gear assembly, through precise meshing, further enhances the synchronicity and precision of the movement between the compass legs, ensuring precise linkage between the needle and pen feet during rotation. The positioning bracket provides a stable mechanical foundation for the gear assembly, which in turn translates this stability into precise motion control, enabling the compass to maintain high accuracy and consistency when drawing circles. This synergistic effect not only improves the drawing accuracy and stability of the electronic compass but also enhances the product's durability and reliability, allowing it to perform exceptionally well in various high-precision drawing scenarios. Attached Figure Description

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be construed as limiting the scope of the present invention. Furthermore, unless specifically indicated, the drawings are only schematic representations of the composition or structure of the described objects and may contain exaggerated depictions, and the drawings are not necessarily drawn to scale.

[0039] Figure 1 This is a schematic diagram of the overall structure of the electronic compass of this utility model;

[0040] Figure 2 This is a structural disassembly diagram of the electronic compass of this utility model;

[0041] Figure 3 This is a schematic diagram of the internal structure of the electronic compass of this utility model;

[0042] Figure 4 This is an assembly diagram of the first and second shaft connections of this utility model;

[0043] Figure 5 Assembly diagram of the two shaft joints and positioning bracket Figure 1 ;

[0044] Figure 6 Assembly diagram of the two shaft joints and positioning bracket Figure 2 ;

[0045] Figure 7 A schematic diagram showing the engagement of the first and second shaft joints via a gear assembly;

[0046] Figure 8 A schematic diagram of the overall structure of the operating part of this utility model;

[0047] Figure 9 This is a schematic diagram of the overall structure of the positioning bracket of this utility model;

[0048] Figure 10 This is a schematic diagram of the internal structure of the main body of this utility model. Detailed Implementation

[0049] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that these descriptions are merely descriptive and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0050] It should be noted that similar labels in the following figures indicate similar items; therefore, once an item is defined in one figure, it will not be further defined and explained in subsequent figures.

[0051] like Figure 1 As shown, the electronic compass 100 of this utility model is an innovative drawing tool that combines the functions of a traditional compass with modern electronic technology. It mainly includes an operating handle 10, a main body 20, needle feet 30, and pen feet 40. The operating handle 10, located at the upper end of the main body 20, is the primary part for user operation of the compass. Preferably, its design conforms to ergonomics, facilitating grip and force application. Specifically, the surface of the operating handle 10 is made of a non-slip material to ensure that it will not slip due to sweaty hands or uneven force during use, thereby improving the stability and accuracy of drawing.

[0052] The main body 20 is the core of the electronic compass. It not only supports the overall structure of the compass but also integrates intelligent measurement and display functions. The main body 20 contains an intelligent measuring device, including a high-precision sensor and controller, which can detect the angle between the needle foot 30 and the line pen foot 40 in real time and calculate the distance between them—the radius of the circle—using an algorithm. This function enables the electronic compass to achieve drawing accuracy far exceeding that of traditional compasses, meeting the needs of various high-precision drawing scenarios such as engineering design, architectural design, and educational demonstrations.

[0053] like Figure 2 As shown, the needle foot 30 and the pen foot 40 are two key components of the electronic compass. They are rotatably mounted on the underside of the main body 20, forming two compass feet p. The front end of the needle foot 30 is equipped with a sharp needle 33 for fixing it to the paper to determine the center position. The design of the needle foot 30 takes into account the adaptability to different paper thicknesses and hardnesses, ensuring stable fixation on various drawing surfaces. The front end of the pen foot 40 is equipped with a replaceable drawing pen 43, allowing users to select different colors and thicknesses of the pen lead to meet various drawing needs.

[0054] During use, the user first fixes the needle 33 of the compass 30 onto the paper to determine the center of the circle. Then, according to the required radius of the circle, the user adjusts the angle between the needle 30 and the pen tip 40 using the operating handle 10. The intelligent measuring device 23 of the electronic compass detects this angle in real time and calculates the corresponding radius value through the controller, ultimately displaying the result clearly on the display screen 22 on the main body 20. The user can precisely adjust the distance between the two tips based on the value on the display screen to ensure that the drawn circle meets the design requirements. This real-time measurement and feedback mechanism greatly improves the accuracy and efficiency of drawing, reducing the inaccuracies caused by human error in traditional compasses.

[0055] It is important to emphasize that in the use of traditional compasses, the perpendicularity of the operating handle to the target surface is a fundamental condition for accurate drawing. However, traditional compasses often lack an effective structure to ensure the stability and consistency of this condition, leading to wobbling or misalignment of the compass feet during actual use, thus affecting the accuracy and stability of the drawing. To solve this problem, this technical solution uses a positioning bracket to ensure that the operating handle of the electronic compass is perpendicular to the target surface, thereby providing a stable structural foundation for high-precision drawing. Furthermore, the precise meshing of the gear assembly further ensures the synchronous movement and precise adjustment of the compass feet. The combined effect of these two aspects significantly improves the drawing accuracy and stability of the compass. Details will be elaborated below:

[0056] Specifically, such as Figure 3 , Figure 5 and Figure 6 As shown, a pivot pin 24 is provided on the housing 21, which is the core component connecting the pin 30 and the pen pin 40. The pivot pin 24 is made of high-strength material to ensure that it can withstand frequent rotation and pressure during long-term use, while maintaining stability and durability.

[0057] like Figures 1 to 4 As shown, the needle 30 includes a first foot 31 and a first shaft connection 32; a needle 33 is mounted on the front end of the first foot 31, and a first shaft connection hole c1 is provided on the first shaft connection 32. The pen foot 40 includes a second foot 41 and a second shaft connection 42; a drawing pen 43 is mounted on the front end of the second foot 41, and a second shaft connection hole c2 is provided on the second shaft connection 42. The shaft pin 24 passes through the first shaft connection hole c1 and the second shaft connection hole c2 respectively.

[0058] like Figure 3 and Figure 4 As shown, the pivot pin 24 passes through the first pivot hole c1 and the second pivot hole c2 respectively, rotatably mounting the needle 30 and the pen tip 40 onto the housing 21. This technique allows the needle 30 and the pen tip 40 to rotate freely around the pivot pin 24, thereby realizing the basic function of a compass—drawing a circle.

[0059] In addition, such as Figures 4 to 7 As shown, the pin 30 and the pen tip 40 are connected by a gear assembly d, a mechanism crucial for ensuring the compass's high precision and stability. Specifically, the gear assembly d includes a gear d1 at the tail end of the first pin 32 and an arc-shaped toothed portion d2 at the tail end of the second pin 42; gear d1 meshes with the arc-shaped toothed portion d2. This meshing is based on the fundamental principle of gear transmission. When the tooth profiles of the two gears mesh, they can transmit power and motion from one shaft to the other. In an electronic compass, this meshing relationship ensures accurate and synchronized movement between the pin 30 and the pen tip 40.

[0060] To achieve a low-cost and highly reliable electronic compass, this technical solution optimizes the compass's internal structure and introduces the intelligent measurement technology described above, thereby significantly improving the compass's drawing accuracy and ease of operation—especially when drawing circles with large radii, where the compass's two legs are prone to wobbling or shifting, affecting the accuracy and stability of the drawing. Therefore, the relevant technical means will be described in detail below:

[0061] like Figure 8 , Figure 9 As shown, a positioning bracket 50 is installed inside the housing 21, which is a key component to ensure the accuracy and stability of the compass. The positioning bracket 50 is composed of a bracket body 51, which is ingeniously designed to accurately position and support the various components of the compass. The upper end of the bracket body 51 has two prongs 52, which take into account the stability of the connection with the operating handle 10. The lower end of the operating handle 10 has two corresponding holes 12, into which the prongs 52 can slide and be inserted, thereby achieving a stable connection between the operating handle 10 and the positioning bracket 50.

[0062] Furthermore, the lower end of the support body 51 is provided with two important positioning holes: a vertical positioning hole 53 and a horizontal positioning hole 54. These two positioning holes are the core parts of the positioning support 50, and together they ensure the precise position and movement of the compass feet. The pivot pin 24 is located in the vertical positioning hole 53, which not only fixes the position of the positioning support 50, but also provides a central axis for the rotation of the compass feet. This makes the movement of the compass feet more stable and reduces errors caused by loosening or wobbling.

[0063] To further improve the accuracy and stability of the compass, at least one locating pin is provided on the first shaft connection 32 or the second shaft connection 41, and the locating pin is located within the transverse locating hole 54. More preferably, the first shaft connection 32 and the second shaft connection 42 are respectively provided with a first locating pin v1 and a second locating pin v2. These two locating pins are located within the transverse locating hole 54, respectively at both ends of the transverse locating hole 54. This technique ensures that the two compass feet always maintain the correct relative position during rotation, thereby ensuring the alignment accuracy of the compass centerline p with the operating handle 10. The fit between the locating pin and the locating hole is very precise, effectively reducing errors caused by mechanical wear or loosening.

[0064] It should be noted that the vertical positioning hole 53 and the horizontal positioning hole 54 are arranged in a cross shape. This design not only improves the positioning accuracy but also enhances the stability of the structure. The cross-shaped design allows the positioning bracket 50 to accurately position the compass feet in multiple directions, thereby ensuring high precision and stability when drawing circles. This structural design plays a crucial role in the electronic compass 100, not only improving the compass's performance but also providing users with a more reliable and convenient drawing experience.

[0065] In summary, with the intervention of the positioning bracket 50, the electronic compass 100 achieves high-precision positioning and stable movement. The positioning bracket 50 features an ingenious structural design. Through the connection between the pin 52 and the socket 12, the cross-shaped design of the vertical positioning hole 53 and the horizontal positioning hole 54, and the precise engagement of the first positioning pin v1 and the second positioning pin v2, the accurate and stable movement relationship of the compass legs is ensured. This design not only improves the drawing accuracy of the compass but also enhances its reliability and stability, providing users with a low-cost and highly reliable electronic compass.

[0066] In this technical solution, the sensor uses a magnetic sensor or a rotary encoder to achieve high-precision detection of the angle between the compass feet. The housing 21 adopts a split design, consisting of a front housing 211 and a rear housing 212. The two are fixed together by a precision connection process to form a whole, which not only ensures the stable installation of internal components, but also facilitates assembly and maintenance.

[0067] Gear d1 has an outer diameter of 3-8 mm and 10-30 teeth; the arc-shaped tooth section d2 has an arc-shaped movement trajectory with a radius of 15-35 mm and 75-105 teeth. This technique ensures that the gears maintain high transmission accuracy despite their relatively small size. Furthermore, through precise waviness detection and control, noise and vibration during gear meshing can be significantly reduced.

[0068] Furthermore, more preferably, gear d1 has an outer diameter of 5.5 mm and 20 teeth; the arc-shaped tooth d2 has an arc-shaped motion trajectory, and the radius of the circle corresponding to the arc trajectory is 26.5 mm, and the arc-shaped tooth d2 has 88 teeth.

[0069] Furthermore, it should be noted that the positioning bracket 50 provides a stable mechanical foundation for the gear assembly d, and the gear assembly d, through precise meshing, translates this stability into precise motion control.

[0070] In the description of this utility model, it should be noted that the terms "upper," "lower," "front," "rear," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Similarly, "first" and "second" are only for ease of understanding and have no other directional meaning, and cannot be considered as limitations on this utility model.

[0071] This paper introduces an electronic compass provided by this utility model. Specific examples are used to illustrate the principle and implementation of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand this utility model and its core ideas. It should be noted that those skilled in the art can make various improvements and modifications to this utility model without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. An electronic compass, characterized in that, It includes an operating handle, a main body, needles, and a pen tip; the operating handle is located at the upper end of the main body, and the needles and pen tips are rotatably mounted on the lower side of the main body to form two compass feet; The main body includes a housing, a display screen, a sensor, and a controller; the display screen is mounted on the housing, and the sensor and controller are connected and installed inside the housing; the sensor detects the angle between the pin and the pen tip, and the distance between the pin and the pen tip is obtained through processing by the controller and displayed on the display screen; The housing is provided with a shaft pin; the pin includes a first foot and a first shaft connection; the front end of the first foot is equipped with a pin, the first shaft connection is provided with a first shaft connection hole, and the tail end of the first shaft connection is provided with a gear. The pen tip includes a second foot and a second shaft connection. A drawing pen is installed at the front end of the second foot. A second shaft connection hole is provided on the second shaft connection. An arc-shaped toothed part is provided at the tail end of the second shaft connection. The shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively. The gear meshes with the arc-shaped toothed part. A positioning bracket is installed inside the housing to keep the center line between the two compass feet substantially aligned with the operating handle.

2. The electronic compass according to claim 1, characterized in that: The positioning bracket includes a bracket body, the upper end of which is provided with two prongs; the lower end of the operating handle is provided with two holes, and the prongs can be slidably inserted into the holes. The lower end of the bracket body is provided with a vertical positioning hole and a horizontal positioning hole; the shaft pin is located in the vertical positioning hole; At least one positioning pin is provided on the first or second shaft connection portion, and the positioning pin is located in the transverse positioning hole.

3. The electronic compass according to claim 2, characterized in that: The vertical positioning hole and the horizontal positioning hole are arranged in a cross shape. The first shaft connection part is provided with a first positioning pin, and the second shaft connection part is provided with a second positioning pin. The first positioning pin and the second positioning pin are respectively located at both ends of the horizontal positioning hole.

4. The electronic compass according to claim 1, characterized in that: The sensor is a magnetic sensor or a rotary encoder.

5. The electronic compass according to claim 1, characterized in that: The housing includes a front shell and a rear shell, which are connected to each other.

6. The electronic compass according to claim 1, characterized in that: The gear has an outer diameter of 3-8mm and 10-30 teeth; the movement trajectory of the arc-shaped tooth is arc-shaped, and the radius of the circle corresponding to the arc trajectory is 15-35mm, and the arc-shaped tooth has 75-105 teeth.

7. An electronic compass, characterized in that: It includes an operating handle, a main body, needles, and a pen tip; the operating handle is located at the upper end of the main body, and the needles and pen tips are rotatably mounted on the lower side of the main body to form two compass feet; The main body includes a housing and an intelligent measuring device installed inside the housing, which can display the included angle between the pin and the pen pin on a display screen outside the housing; The housing is provided with a shaft pin, and the pin and the thread pen are both provided with shaft connection holes. The pin and the thread pen are connected to the shaft pin together through the shaft connection holes. A positioning bracket is installed inside the housing. The positioning bracket includes a bracket body, and the upper end of the bracket body is provided with two prongs. The lower end of the operating handle is provided with two holes, and the prongs are inserted into the holes. The connecting handle at the lower end of the bracket body is provided with a vertical positioning hole and a horizontal positioning hole; a positioning pin is provided on one side of the shaft connection hole of the needle or the shaft connection hole of the thread pen. The shaft pin is located in the vertical positioning hole, and the positioning pin is located in the horizontal positioning hole, so that the center line between the operating handle and the two compass feet is on the same straight line; The pin and the pen tip are connected by a gear assembly to achieve synchronous rotation.

8. An electronic compass according to claim 7, characterized in that: The pin includes a first foot and a first shaft connection; a pin is installed at the front end of the first foot, and a first shaft connection hole is provided on the first shaft connection; The pen foot includes a second foot and a second shaft connection. A drawing pen is installed at the front end of the second foot. A second shaft connection hole is provided on the second shaft connection. The shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively. The gear assembly includes a gear at the tail end of the first shaft connection portion and an arc-shaped tooth portion at the tail end of the second shaft connection portion; the gear meshes with the arc-shaped tooth portion; The gear has an outer diameter of 3-8mm and 10-30 teeth; the movement trajectory of the arc-shaped tooth is arc-shaped, and the radius of the circle corresponding to the arc trajectory is 15-35mm, and the arc-shaped tooth has 75-105 teeth.

9. An electronic compass according to claim 7, characterized in that: The pin includes a first foot and a first shaft connection, and the pen foot includes a second foot and a second shaft connection; the shaft pin passes through the first shaft connection hole and the second shaft connection hole respectively; The vertical positioning hole and the horizontal positioning hole are arranged in a cross shape. The first shaft connection part is provided with a first positioning pin, and the second shaft connection part is provided with a second positioning pin. The first positioning pin and the second positioning pin are respectively located at both ends of the horizontal positioning hole.

10. An electronic compass according to claim 8, characterized in that: The intelligent measuring device includes a sensor and a controller installed inside the housing; the sensor is a magnetic sensor or a rotary encoder. The sensor detects the angle between the needle and the pen tip, and the distance between the needle and the pen tip is obtained through the controller and displayed on the screen. The housing includes a front shell and a rear shell, which are connected to each other.

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