Lens driving device
By using closed-loop lens driving device in automatic focus cameras with portable terminal devices such as mobile phones, and using position detection and feedback control of Hall magnets and Hall chips, the problems of slow focus speed and low accuracy are solved, and fast Accurate focus and low power consumption improve imaging effects and promote miniaturization and thinning of the device.
Patent Information
- Application Number
- CN201610816847.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2016-09-12
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2036-09-12
AI Technical Summary
The automatic focus camera lens driving device of existing portable terminal devices such as mobile phones is slower during the focusing process, has low accuracy and high power consumption, and is prone to unstable position due to inertial shaking, affecting the imaging effect.
Using a closed-loop lens driving device, the lens position detection unit of Hall magnet and Hall chip is installed on the lens support, and precise position detection and feedback control are used to use the Hall effect, combined with the design of the shield cover and magnet, reduce magnetic field interference. , achieve fast and accurate focus.
It achieves improved focus accuracy, reduced power consumption, accelerated focus speed, strong anti-interference ability, reduces motor running hysteresis and poor posture, ensures imaging effect, and performs better especially when there is insufficient light, and promotes the miniaturization of the device. and thinner.
Smart Images
Figure CN106443949B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a closed-loop lens driving device, and more particularly to a lens driving device installed in a mobile phone or the like and driving a lens of an auto-focus camera therein. Background Art
[0002] The lens driving device of the autofocus camera mounted on a portable terminal device such as a mobile phone is generally composed of: a lens support body that supports the lens on the inner periphery; a coil body disposed on the outer periphery of the lens support body; a spring that elastically supports the lens support body; and multiple magnets disposed around the inner side of the ring mouth at a certain interval ratio and arranged opposite to the coil body. When the coil is energized, the interaction between the magnet and the coil generates an electromagnetic force, which drives the lens support body to move in the direction of the optical axis and stays at a position that is balanced with the elastic force of the spring. By controlling the coil current, the lens support body is driven to move to the specified target position, thereby achieving the purpose of focusing.
[0003] However, this focusing process is relatively time-consuming, because the lens will not stop immediately when it moves to the position, and will shake at the expected position due to inertia and other factors, so it needs a stabilization period to maintain, and the actual position where it stops may not coincide with the specified position for evaluation. Summary of the invention
[0004] In order to solve the problems existing in the prior art, an object of the present invention is to provide a lens driving device, which has the advantages of low energy consumption, fast and precise movement, and fast focusing speed.
[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows: a lens driving device, comprising a lens support body, a coil wound around the periphery of the lens support body, an upper cover arranged above the lens support body, and a lower cover arranged below the lens support body, the outer cover of the lens support body is provided with a shielding cover, characterized in that the corresponding two inner walls of the shielding cover are provided with driving magnets, the other side wall of the shielding cover is provided with a PCB board, the PCB board is provided with a Hall chip, the corresponding position of the lens support body is provided with a Hall magnet back gasket and a Hall magnet, the Hall magnet and the Hall chip are spaced and arranged opposite to each other in space, and the PCB board and the Hall chip thereon and the above-mentioned Hall magnet constitute a lens position detection unit.
[0006] According to a preferred embodiment of the present invention, two different inner peripheral side walls of the shielding cover are respectively provided with a long strip driving magnet, and the two long strip driving magnets are opposite to each other.
[0007] According to a preferred embodiment of the present invention, an opening notch is provided at an upper corner of the outer circumference of the lens support body, and the opening notch accommodates the Hall magnet back gasket and the Hall magnet in sequence from the inside to the outside.
[0008] According to a preferred embodiment of the present invention, an upper gasket is arranged above the upper cover, an upper spring is clamped between the upper gasket and the upper cover, and a lower spring is arranged between the lens support body and the lower cover for supporting the lens support body.
[0009] According to a preferred embodiment of the present invention, the Hall magnet is magnetized with four poles, and the non-magnetic area of the magnet is no larger than 0.2 mm, thereby enhancing the induction intensity of the magnetic field.
[0010] According to a preferred embodiment of the present invention, in the lens driving device, the Hall magnet back gasket is made of stainless steel with high magnetic properties, which can effectively protect and enhance the magnetic flux strength of the Hall magnet.
[0011] The technical effects of the present invention are:
[0012] 1. The lens driving device of the present invention has the characteristics of high focusing accuracy, faster focusing, lower power consumption, etc., and has a better imaging effect when matched with the lens. Even in the case of insufficient light, the imaging effect is more prominent.
[0013] 2. In the closed-loop control of the present invention, since the control subject can discover and correct the deviation of the operation of the controlled object according to the feedback information, it has a strong anti-interference ability and can perform effective control, thereby ensuring the realization of the predetermined goal.
[0014] 3. The closed-loop lens driving device of the present invention can relatively shorten the settling time, reduce the hysteresis of the motor operation, and solve the problem of poor posture.
[0015] 4. The two strip-shaped driving magnets in the present invention are respectively installed on two opposite sides of the shielding cover, and the Hall magnet is installed in the opening notch of the lens support body. The driving magnet and the Hall magnet are spaced relatively large from each other, and each is assembled with strict precautions, so the structure eliminates the magnetic field interference such as mutual attraction or repulsion that may be generated between the driving magnet and the Hall magnet. Since the driving magnet eliminates negative effects and influences on the Hall magnet and the Hall chip in the spatial structure, it will not hinder the stable signal output and action of the sensor. In other words, it will not affect the correct position of the calculation lens.
[0016] 5. In the closed-loop structure of the present invention, since the drive magnet and the Hall magnet will not interfere with each other in the configuration structure and will not cause any obstacles to the assembly work, it becomes possible to further miniaturize and thin the lens drive device. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a complete three-dimensional schematic diagram of the closed-loop lens driving device of the present invention.
[0018] Figure 2 This is a schematic diagram of the cross-sectional structure of the internal component assembly of the closed-loop lens drive device.
[0019] Figure 3 This is an exploded view of the internal components of a closed-loop lens drive device.
[0020] Figure 4 This is a schematic diagram showing the assembly effect of the positional relationship between the shield, driving magnet, Hall magnet, and Hall chip.
[0021] Figure 5 This is a schematic diagram of the position relationship and movement direction of the Hall magnet and Hall chip.
[0022] Figure 6 Schematic diagram of the four-pole magnetization of the Hall magnet.
[0023] Figure 7 Construct a schematic for the PCB board assembly.
[0024] Figure 8 for Figure 7 The back side.
[0025] Fig. 9 This is the state before the Hall gasket and Hall magnet are installed into the lens support body.
[0026] Fig.10 This is the state after the Hall gasket and Hall magnet are installed in the lens support body.
[0027] The figure includes: a lens support body 1, a coil 2, an upper cover 3, a lower cover 4, a shielding cover 5, an upper gasket 6, an upper spring 7, a lower spring 8, a driving magnet 9, a PCB board 10, a Hall chip 11, a Hall magnet back gasket 12, a Hall magnet 13, a capacitor 14, a terminal pin 15, a notch 16, an opening notch 17, a flange 18, and a non-magnetic area 19. DETAILED DESCRIPTION
[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] As shown in the figure, a lens driving device comprises a lens support body 1, a coil 2 wound around the outer periphery of the lens support body 1, an upper cover 3 arranged above the lens support body 1, and a lower cover 4 arranged below the lens support body 1, wherein the upper cover 3 and the lower cover 4 are interlocked with each other to form a frame configuration, a shielding cover 5 is provided on the outer cover of the lens support body, an upper gasket 6 is provided above the upper cover 3, an upper spring 7 is clamped between the upper gasket 6 and the upper cover 3, and a lower spring 8 is provided between the lens support body 1 and the lower cover 4 for supporting the lens support body; it is characterized in that the corresponding two inner side walls of the shielding cover 5 are provided with driving magnets 9, the other side wall of the shielding cover 5 is provided with a PCB board 10, a Hall chip 11 is provided on the PCB board 10, a Hall magnet back gasket 12 and a Hall magnet 13 are provided at the corresponding position of the lens support body 1, the Hall magnet 13 and the Hall chip 11 are spaced and arranged opposite to each other in space, and the PCB board 10 and the Hall chip 11 thereon and the above-mentioned Hall magnet 13 constitute a lens position detection unit.
[0030] like Figure 4 As shown, the shielding cover 5 is a four-corner shell shape with four sides when viewed in a plane, and two mutually opposite sides of the shielding cover 5 are respectively provided with a long strip driving magnet 9. A PCB board assembly is arranged on the inner side of the shorter side wall of the shielding cover adjacent to the two driving magnet sides. The PCB assembly 10 is composed of a Hall chip 11, a capacitor 14 and a PCB board 10 with four terminal pins. The Hall chip 11 and the capacitor 14 are placed on the same side of the PCB board 10. The PCB board assembly and the above-mentioned Hall magnet constitute a lens position detection mechanism, and the Hall magnet 13 and the Hall chip 11 are spaced and arranged opposite to each other in space. Four terminal pins 15 are arranged at the bottom of the PCB board 10, and the four terminal pins 15 face the inner peripheral wall side of the shielding cover, and two of the pins are connected to the positive and negative ends of the lower spring terminal. The input and output functions of the power information of the closed-loop lens driving device are all realized by the four terminal pins.
[0031] The shielding cover is a non-magnetic soft stainless steel material. It has grounding anti-static and electromagnetic shielding functions during the external connection process. After the shielding cover is added, it can greatly reduce the interference of the motor coil on the signal collected by the high-frequency module during operation and enhance the call quality. After the shielding cover of the motor is grounded, it can prevent static electricity generated by the signal and other static electricity generated by friction, thereby preventing damage to the motor.
[0032] The upper gasket is installed between the shield and the upper spring. It is a square plate structure, made of the same material and hardness as the spring. Its flatness allows the assembled lens to be driven smoothly on the axis without tilting.
[0033] The lens support body is cylindrical in the direction of the optical axis diameter and is clamped and fixed by upper and lower springs. The inner peripheral side is provided with a lens, and the outer peripheral side is provided with a coil, and the outer peripheral side shape is consistent with the inner peripheral shape of the coil.
[0034] like Fig. 9 As shown, the lens support body is provided with a notch 16 at the four corners of the upper side of the outer circumference, and the notch matches with the four flanges 18 on the inner side of the shielding cover to prevent the lens support body from tilting and shaking in the circumferential X and Y axes or the Z axis direction of the optical axis when it is driven. Fig. 9 As shown, the upper corner of the lens support body is provided with an opening notch 17, which vertically receives the metal Hall magnet back gasket 12 and the Hall magnet 13 from the inside to the outside. The Hall magnet back gasket 12 is made of stainless steel high magnetic material, which can effectively protect and enhance the magnetic flux strength of the Hall magnet 13, and can assemble the Hall magnet more smoothly.
[0035] like Figure 4 As in the assembled state, the Hall chip and the Hall magnet are arranged opposite to each other with a certain space between them. The position detection mechanism for detecting the position of the lens support body is realized by the PCB assembly and the Hall magnet. Through the Hall effect of the Hall chip, the Gauss value in the magnetic field can be measured to determine the position of the lens support body.
[0036] Figure 5 This is a schematic diagram of the position relationship and movement direction of the Hall magnet and Hall chip. Figure 6 According to a preferred embodiment of the present invention, the above-mentioned Hall magnet adopts 4-pole magnetization. As shown in the figure, through the 4-pole magnetization method, the upper end of the Hall magnet is set as a magnetic area with an outer S pole and an inner N pole, and the lower end is set as a magnetic area with an inner S pole and an outer N pole. The non-magnetic area 19 between the upper and lower ends is not more than 0.2mm, thereby enhancing the induction intensity of the magnetic field.
[0037] The closed-loop focus driving device of the present invention adopts a closed-loop focus technology. The lens position control method is based on the Hall effect principle of the Hall sensor in the Hall chip. The specific operating principle is that after the Gauss value of the initial position (unactivated state) of the lens is sensed by the Hall sensor, the Gauss value of the maximum activated position is sensed, and the measured Gauss value is stored in the Hall chip, and the analog value of the Hall sense is converted into a digital signal. Different Gauss values of the Hall magnet at different positions are detected and different code messages are given respectively, thereby moving the lens. The Hall chip converts the sensed magnetic flux density into high and low signals, and uses the sensed position to write the movement information of the ideal position of the lens.
[0038] In other words, the Hall chip is used to sense the magnetic field strength of the lens at the 0 and max positions, and the E 2ROM is effectively driven by the physical position. During the movement of the lens, we can continuously measure the magnetic field strength at the moving position. When the gap between the Hall magnet and the chip does not change, the magnetic field strength at the same position in the up and down displacement of the Hall sensor remains basically unchanged during the up and down movement of the carrier. This intensity is fed back to the Hall chip, and the chip obtains positive and negative errors based on the feedback value. Then, the positive and negative errors are used to control the movement direction and speed of the lens, so that the focus can be achieved more accurately and quickly in a very short time.
[0039] The closed-loop lens drive device introduces a lens position detection mechanism, which is equivalent to an additional feedback control method, so that the lens in the lens support body can be shifted more accurately each time, reducing the number of times the lens moves back and forth, thereby increasing the focusing speed.
[0040] In the closed-loop lens driving device of the present invention, the position detection mechanism is configured to detect the position of the lens by utilizing the Hall effect.
[0041] The above-mentioned Hall magnet adopts quadrupole magnetization, so the non-magnetic area of the magnet will be very small, only 0.2mm, which enhances the induction intensity of the magnetic field. The use of this Hall magnet and Hall element sensor has fast focusing and reduces the shaking back and forth near the focus position. When the current is passed through the Hall element sensor and the magnetic field is applied from the outside, the Hall effect of the electromotive force (Hall output voltage) is generated in the direction perpendicular to the magnetic field. According to the corresponding magnetic field of the Hall magnet position that generates the magnetic field, the Hall output voltage value of the Hall element sensor is detected by the measuring device, and further the position of the lens support is calculated by the calculation device.
[0042] The closed-loop lens driving device of the present invention has the characteristics of high focusing accuracy, faster focusing, lower power consumption, etc., and has a better imaging effect when matched with the lens. Even in the case of insufficient light, the imaging effect is more prominent.
[0043] In the closed-loop control of the present invention, since the control subject can discover and correct the deviation of the operation of the controlled object according to the feedback information, it has a strong anti-interference ability and can perform effective control, thereby ensuring the realization of the predetermined goal.
[0044] The closed-loop lens driving device of the present invention can relatively shorten the settling time, reduce the hysteresis phenomenon of the motor operation, and solve the problem of poor posture.
[0045] The two strip-shaped driving magnets in the present invention are respectively installed on two opposite sides of the shielding cover, and the Hall magnet is installed in the opening notch of the lens support body. The driving magnet and the Hall magnet are spaced relatively large to avoid mutual interference of magnetic fields, and each is assembled with strict precautions, so the structure eliminates the magnetic field interference such as mutual attraction or repulsion that may be generated between the driving magnet and the Hall magnet. Since the driving magnet eliminates negative effects and influences on the Hall magnet and the Hall chip in the spatial structure, it will not hinder the stable signal output and action of the sensor. In other words, it will not affect the correct position of the calculation lens.
[0046] The closed-loop structure of the present invention does not interfere with each other in the configuration structure of the driving magnet and the Hall magnet, and does not cause any obstacles to the assembly work, so that further miniaturization and thinning of the lens driving device becomes possible.
[0047] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to the above descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.
Claims
1. A lens driving device, comprising a lens support body, a coil wound around the periphery of the lens support body, an upper cover arranged above the lens support body, a lower cover arranged below the lens support body, and a shielding cover is arranged on the outer cover of the lens support body, characterized in that The two corresponding inner side walls of the shielding cover are provided with driving magnets, the other side wall of the shielding cover is provided with a PCB board, the PCB board is provided with a Hall chip, the corresponding position of the lens support body is provided with a Hall magnet back gasket and a Hall magnet, the Hall magnet and the Hall chip are spaced and arranged opposite to each other in space, the PCB board and the Hall chip thereon and the Hall magnet constitute a lens position detection unit, and the Hall magnet adopts quadrupole magnetization; Two different inner peripheral side walls of the shielding cover are respectively provided with a long strip driving magnet, and the two long strip driving magnets are opposite to each other; An opening notch is provided at the upper corner of the outer circumference of the lens support body, and the opening notch accommodates the Hall magnet back gasket and the Hall magnet in sequence from the inside to the outside.
2. A lens driving device as claimed in claim 1, characterized in that: An upper gasket is arranged above the upper cover, an upper spring is clamped between the upper gasket and the upper cover, and a lower spring is arranged between the lens support body and the lower cover for supporting the lens support body.
3. A lens driving device as claimed in claim 1, characterized in that: The non-magnetic area of the Hall magnet is no larger than 0.2 mm.
4. A lens driving device as claimed in claim 1, characterized in that: In the lens driving device, the Hall magnet back gasket is made of stainless steel with high magnetic properties.