KR-102964544-B1 - Magnetic sensor assembly for sensing rotational positions of a camera module

KR102964544B1KR 102964544 B1KR102964544 B1KR 102964544B1KR-102964544-B1

Abstract

The present invention relates to a magnetic sensor assembly that senses the rotational position of a camera module according to a change in magnetic force. The magnetic sensor assembly comprises: a rotating member that rotates together with the camera module; a magnet member comprising a first multi-pole magnetizing magnet having a first number of pole pairs arranged alternately along a first circumference on the rotating member and a second multi-pole magnetizing magnet having a second number of pole pairs different from the first number arranged alternately along a second circumference concentric with the first circumference on the rotating member; a Hall sensor that detects changes in the magnetic field generated by the first and second multi-pole magnetizing magnets fixed to one side of a housing and rotating; and a processor that calculates the initial position of the rotating member and the angle of rotation from the initial position of the rotating member through the detected changes in the magnetic field.

Inventors

김창연
공원준
박종인
이경재

Assignees

한화비전 주식회사

Dates

Publication Date: 20260512
Application Date: 20200316

Claims (14)

As a magnetic sensor assembly for sensing the rotational position of a camera module, A rotating member that rotates together with the camera module above; A first multi-pole magnetizing magnet having a first number of pole pairs, alternately arranged along a first circumference on the rotating member, and a second multi-pole magnetizing magnet having a second number of pole pairs different from the first number, alternately arranged along a second circumference on the rotating member that forms a concentric circle with the first circumference and is located adjacent to the radially inner side with respect to the first circumference. A magnet member comprising at least one slot located inward from the first and second multi-pole magnetizing magnets and formed elongated along a third circumference smaller than the first and second circumferences with respect to the radial direction; A Hall sensor for detecting changes in the magnetic field generated by the first and second multi-pole magnetizing magnets fixed and rotating on one side of the housing; and A processor that calculates the initial position of the rotating member and the rotation angle of the rotating member from the initial position through the change in the detected magnetic field, The above-mentioned rotating member is, A rotating pulley that rotates by receiving driving force from a motor; and It includes a bracket on which the camera module is mounted and which is coupled to the rotating pulley to rotate together and transmit rotational force to the camera module. A magnetic sensor assembly in which the circumferential position of the first and second multi-pole magnetizing magnets can be adjusted by moving the magnet member in a circumferential direction with the fastening member penetrating the at least one slot, and the magnet member is completely fixed on the bracket by fastening the fastening member to the bracket with the fastening member penetrating the at least one slot.
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In paragraph 1, The above-mentioned first number is a magnetic sensor assembly that forms a relative prime relationship with the above-mentioned second number.
In paragraph 3, A magnetic sensor assembly in which the first number is 1 greater than the second number.
In paragraph 1, A magnetic sensor assembly in which the magnet member is installed on the bracket, and the magnet member is configured to be concentric with respect to the bracket and non-concentric with respect to the motor shaft of the motor.
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In paragraph 1, The above magnet member further includes a marker indicating a reference point of the above magnet member, and A magnetic sensor assembly in which the magnet member and the bracket are fixed by the at least one fastener while the marker aligns with another marker on the bracket.
In paragraph 5, the above housing is A case including a support for fixing a circuit board on which the above-mentioned Hall sensor is placed; A stage coupled to the bracket and rotating together with the bracket; and A magnetic sensor assembly comprising at least one bearing that supports rotation of the stage between the case and the stage.
In paragraph 8, the above housing is The above case and the above stage further include a cover covering from above, The above circuit board is a magnetic sensor assembly fixed to both the lower surface of the cover and the support of the case.
In paragraph 8, A spacer whose inner diameter is fixed to the outer diameter of the stage and extends radially; and A magnetic sensor assembly further comprising an elastic member interposed under preload between the spacer and the bracket.
In Paragraph 10, A magnetic sensor assembly in which the design gap between the spacer and the bracket is maintained even when a compressive force is generated between the spacer and the bracket, by the elastic member deforming with the preload.
In paragraph 8, A magnetic sensor assembly having a memory that stores a set value of the Hall sensor together with the Hall sensor on the circuit board above.
In paragraph 1, The above processor is a magnetic sensor assembly that uses the moving average of sample values obtained from the Hall sensor to calculate an accurate rotation angle.
In paragraph 1, The above camera module is a camera module that supports pan/tilt/zoom, and The above processor performs an operation to correct the rotational position of the above-described rotating member, wherein the correcting operation is performed only during the idle time of the camera module pan/tilt operation, a magnetic sensor assembly.

Description

Magnetic sensor assembly for sensing rotational positions of a camera module The present invention relates to a sensor assembly for sensing the position of a rotating member, and more specifically, to a magnetic sensor assembly for sensing the rotational position of a camera module according to a change in magnetic force. Among surveillance cameras, PTZ cameras that provide Pan/Tilt/Zoom functions offer preset movement between set coordinate values, and in this case, the error between each designated coordinate value and the actual area captured by the camera must be small. The error between the designated coordinate value and the area captured by the camera is called preset accuracy, and this value typically needs to be controlled so that it does not exceed 0.2°. In order to ensure the accuracy of the above preset drive, equipment is required to re-detect the error between the amount of rotation of the motor shaft and the amount of rotation of the actual camera. As such position detection sensors, Hall sensors that detect the magnetic field of the rotating body and photo sensors or photo interruptor sensors (PI sensors) that detect light blockage of the rotating body are known. The above photo interruptor sensor method is a method in which a light receiving unit detects a light blocking pattern in which light emitted from a light-emitting unit is blocked or passed by a plurality of photo interrupters, and the Hall sensor method is a method in which a magnetic field that changes according to the rotation of a rotating member is detected by a magnetic sensor instead of such photo interrupters. Conventional Hall sensor methods were generally used simply for initial position detection. A single-pole magnetized magnet approached the Hall sensor to detect the nearest position, and the initial position was calculated based on the detected position. While this Hall sensor method has the advantages of low cost and ease of configuration, it has the disadvantage that feedback control is difficult because position information is not recognized if the magnet does not pass through the area detectable by the Hall sensor. In addition, since proximity between the Hall sensor and the magnet must be achieved, a separate driving mode is required for initial position detection, and time is required for initial position detection, and there is also a disadvantage that an error in the initial position occurs depending on the approach direction. Therefore, it is necessary to improve such conventional Hall sensors so that they can detect the current direction (initial position) regardless of the rotational position of the rotating member, and measure the real-time rotation angle of the rotating member with uniform resolution. FIG. 1 is an assembled perspective view of a magnetic sensor assembly that senses the rotational position of a camera module according to one embodiment of the present invention. Figure 2 is an exploded perspective view of the magnetic sensor assembly of Figure 1. Figure 3 is a bottom view of the magnetic sensor assembly with the lower case removed and viewed from below. FIG. 4 is a perspective view with the outer cover and power generation/transmission structure removed from the magnetic sensor assembly. FIG. 5 is a plan view showing only the rotating member including the bracket and rotating pulley and the magnet member in FIG. 4. FIG. 6 is a cross-sectional perspective view of a magnetic sensor assembly cut radially. Figure 7 is a plan view of the magnetic sensor assembly cut at a different angle from Figure 6. Figure 8 is an enlarged plan view of area C of Figure 7. FIG. 9 is a perspective view illustrating a circuit board according to one embodiment of the present invention. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise. The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically