Automatic focusing actuator

Abstract

The invention relates to the technical field of optical camera shooting, and discloses an automatic focusing actuator which comprises a base, a lens support, a guiding system and a driving system. The driving system comprises a driving unit, a limiting keeping unit and a control feedback unit; the limiting and maintaining unit is installed on the base, the driving unit and the control feedback unit are installed on the limiting and maintaining unit, the limiting and maintaining unit is used for limiting the driving unit, and the control feedback unit is used for controlling power on-off of the driving unit and obtaining movement information of the lens support. Automatic focusing is carried out by adopting a friction force driving mode, so that the required thrust can be ensured, the positioning accuracy can be improved, low-cost and simple-structure configuration can be realized through the minimum number of parts, and low power consumption can be realized; meanwhile, due to the mechanical connection relation, no extra stabilizing equipment needs to be arranged when the equipment encounters external vibration, impact and other mechanical interferences, the spatial position of the lens is relatively stable, and the anti-interference capability is relatively high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging technology, in particular to an automatic focusing actuator. BACKGROUND

[0002] The mainstream driving mode of the actuator used by the automatic focusing system is the voice coil motor (VCM) electromagnetic driving scheme. In the working process, a constant magnetic field is generated by continuously applying a stable voltage to the coil to lock the focusing position of the imaging lens. This working characteristic causes continuous power consumption of the device in the focusing state, which directly affects the endurance performance of the whole machine, especially in portable imaging devices. In addition, the essence of electromagnetic driving is a non-contact driving structure, and there is no rigid connection between the lens assembly and the driving mechanism. When the device encounters external mechanical disturbances such as vibration and impact, the spatial position of the lens is easily shifted slightly, thereby destroying the calibrated focusing state. Therefore, in order to ensure the stability of the imaging, a lens position maintaining device is additionally provided to offset the position deviation caused by external disturbances through mechanical limiting or closed-loop feedback adjustment to ensure the stability of the focusing accuracy. The additional configuration not only increases the investment cost but also increases the complexity of the device. SUMMARY

[0003] The purpose of the present application is to provide an automatic focusing actuator to solve the problem of fast power consumption and poor stability of the existing electromagnetic focusing actuator to maintain the focusing position.

[0004] The present application is implemented by the following technical scheme: an automatic focusing actuator, comprising: a base for accommodating a lens holder; a lens holder provided with a lens mounting hole for mounting a lens module; a guide system for guiding the lens holder to slide along the lens axis in the base to achieve focusing; a driving system for providing driving force for the movement of the lens holder; the driving system comprises a driving unit, a position limiting unit and a control feedback unit; the position limiting unit is installed on the base, the driving unit and the control feedback unit are installed on the position limiting unit, the position limiting unit is used for limiting the driving unit, and the control feedback unit is used for controlling the power on-off of the driving unit and obtaining the movement information of the lens holder.

[0005] In order to better implement the present application, further, the driving unit comprises an AF driving board, a protruding block and a PUS piezoelectric element, the protruding block is installed at the end of the PUS piezoelectric element, the AF driving board is installed on the lens holder, and the AF driving board is in contact with the protruding block.

[0006] In order to better realize the present application, further, the control feedback unit comprises an AF sensor magnet, which is installed on the lens holder, and a Hall / FPC, which is installed on the position retaining unit and is electrically connected with the PUS piezoelectric element, and the Hall / FPC cooperates with the AF sensor magnet.

[0007] In order to better realize the present application, further, the position retaining unit comprises a position retaining piece, which is installed on the base, and the position retaining piece comprises a position retaining frame and a retaining damper, which is installed on the position retaining frame and is used for retaining the deformed side of the PUS piezoelectric element, and both ends of the position retaining frame are provided with accommodating openings, and the PUS piezoelectric element is placed in the accommodating openings.

[0008] In order to better realize the present application, further, the position retaining piece further comprises a pressurizing spring, which is installed on the position retaining frame and is used for exerting pressure on the end of the PUS piezoelectric element to drive the protruding block to abut against the AF driving plate.

[0009] In order to better realize the present application, further, the position retaining unit further comprises a position retaining plate, which is installed on both sides of the position retaining piece and is used for retaining the non-deformed side of the PUS piezoelectric element.

[0010] In order to better realize the present application, further, the guiding system comprises a guiding unit and a stability maintaining unit, and both the guiding unit and the stability maintaining unit are arranged between the base and the lens holder.

[0011] In order to better realize the present application, further, the lens holder is provided with a guiding shaft arm and an AF driving arm, and both the guiding shaft arm and the AF driving arm are provided with a sliding groove, and the base is also provided with a matching sliding groove corresponding to the guiding shaft arm and the AF driving arm, the guiding unit comprises an AF guiding ball and an AF guide rail, the AF guide rail is installed in the sliding groove at the guiding shaft arm, and a plurality of AF guiding balls are installed in the sliding groove at the AF driving arm.

[0012] In order to better realize the present application, further, the stability maintaining unit comprises a magnetic force adsorption block and an adsorption magnet, the magnetic force adsorption block is installed on the guiding shaft arm, and the adsorption magnet is installed on the base, and the magnetic force adsorption block cooperates with the adsorption magnet.

[0013] Compared with the prior art, the present application has the following advantages and beneficial effects: (1) The present application adopts friction drive to realize automatic focusing, which can ensure the required thrust and improve positioning accuracy, and realizes low cost, simple structure and low power consumption by using the least number of components, thereby reducing production cost; meanwhile, due to the connection relationship, the device does not need additional stabilization equipment when encountering external vibration, impact and other mechanical disturbances, and the spatial position of the lens is relatively stable, and the anti-interference ability is strong; (2) The present application sets a limiting retaining unit, which keeps the damper adaptive to the change of the PUS piezoelectric element during the power-on operation of the PUS piezoelectric element, so that the PUS piezoelectric element is always limited by the retaining damper, avoiding the invalid expansion of the PUS piezoelectric element, and improving the displacement accuracy of the AF drive board; meanwhile, the elastic force of the compression spring makes the protrusion resist on the AF drive board to provide sufficient friction, improving the working stability of the PUS piezoelectric element and the lens position stability; (3) The present application utilizes the magnetic attraction of the magnetic adsorption block and the adsorption magnet to realize the stabilization of the position and movement of the lens holder; when the lens holder is impacted or vibrated by external force, the friction force of the AF drive board and the PUS piezoelectric element, the side pressure of the guide shaft arm, and the magnetic attraction force of the magnetic adsorption block and the adsorption magnet are combined, so that the position of the lens holder can be stably kept. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the present application.

[0015] Figure 2 It is a sectional view of the overall structure of the present application.

[0016] Figure 3 It is a schematic diagram of the internal structure of the present application.

[0017] Figure 4 It is a schematic diagram of the guide system and the drive system structure.

[0018] Figure 5 It is a schematic diagram of the drive system structure.

[0019] Figure 6 It is a schematic diagram of the limiting retaining piece and the PUS piezoelectric element structure.

[0020] Figure 7 It is a schematic diagram of the limiting retaining piece structure.

[0021] Figure 8 It is a working principle diagram of the PUS piezoelectric element.

[0022] Wherein: 101-base; 102-lens holder; 103-guide shaft arm; 104-magnetic adsorption block; 105-adsorption magnet; 106-AF guide rail; 107-AF drive arm; 108-AF guide ball; 109-AF drive plate; 110-bump; 111-PUS piezoelectric element; 112-AF sensor magnet; 113-Hall / FPC; 114-limiting retaining member; 1141-limiting frame; 1142-pressurizing spring; 1143-retaining damper; 1144-receiving port; 115-limiting plate. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0024] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, can be electrically connected; can be directly connected, can be indirectly connected through an intermediate medium, or can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances. Embodiment 1

[0025] The embodiment provides an automatic focusing actuator, specifically as shown in Figures 1-4 , Figure 8 , comprising: a base 101 for accommodating a lens holder 102; the lens holder 102 is provided with a lens mounting hole for carrying a lens module; a guide system for guiding the lens holder 102 to slide along the lens axis in the base 101 to achieve focusing; a drive system for providing driving force for the movement of the lens holder 102.

[0026] The drive system includes a drive unit, a limit holding unit, and a control feedback unit. The limit holding unit is mounted on the base 101, and the drive unit and control feedback unit are mounted on the limit holding unit. The limit holding unit is used to limit the drive unit, and the control feedback unit is used to control the power supply of the drive unit and acquire the movement information of the lens bracket 102. The drive unit includes an AF drive plate 109, a protrusion 110, and a PUS piezoelectric element 111. The protrusion 110 is mounted on the end of the PUS piezoelectric element 111, and the AF drive plate 109 is mounted on the lens bracket 102, with the AF drive plate 109 abutting against the protrusion 110.

[0027] When the lens mount 102 is needed to mount the lens for focusing, the control feedback unit controls the PUS piezoelectric element 111 to turn on the power and applies a driving voltage (sine wave or square wave) to the PUS piezoelectric element 111, at which time the PUS piezoelectric element 111 will deform. Figure 8 As shown, the PUS piezoelectric element 111 has four regions arranged diagonally as one group, for a total of two groups. When the applied voltage is negative, the power supply region shrinks; when the applied voltage is positive, the power supply region stretches. This characteristic allows the PUS piezoelectric element 111 to deform while utilizing the friction between the protrusion 110 and the AF drive plate 109 to push the AF drive plate 109, thereby driving the lens support 102 to move the lens and complete the focusing operation. When it is necessary to maintain the focused position, the PUS piezoelectric element 111 is de-energized. Due to the friction between the protrusion 110 and the AF drive plate 109, the focusing state can still be maintained, and no power consumption is generated. Using this method for autofocus ensures the required thrust while improving positioning accuracy. It achieves a low-cost, simple structure with a minimal number of parts, thereby reducing production costs and achieving low power consumption. Example 2:

[0028] This embodiment further expands the drive system based on the above embodiments, specifically as follows: Figures 2-7 As shown, the control feedback unit includes an AF sensor magnet 112 and a Hall / FPC 113. The AF sensor magnet 112 is mounted on the lens bracket 102, and the Hall / FPC 113 is mounted on the limiting and holding unit and electrically connected to the PUS piezoelectric element 111. The Hall / FPC 113 cooperates with the AF sensor magnet 112.

[0029] Hall / FPC113 controls the power supply to and from the PUS piezoelectric element 111. At the same time, by using the AF sensor magnet 112 in conjunction with Hall / FPC113, the displacement of the lens support 102 can be detected, thereby achieving the purpose of automatic focus adjustment.

[0030] Furthermore, the limiting and retaining unit includes a limiting and retaining member 114, which is mounted on the base 101. The limiting and retaining member 114 includes a limiting frame 1141 and a retaining damper 1143. The retaining damper 1143 is mounted on the limiting frame 1141 and is used to limit and retain the deformation side of the PUS piezoelectric element 111. Both ends of the limiting frame 1141 are provided with receiving openings 1144, and the PUS piezoelectric element 111 is placed in the receiving openings 1144.

[0031] When the PUS piezoelectric element 111 is placed in the receiving port 1144, the retaining dampers 1143 on both sides will limit the PUS piezoelectric element 111. During the operation of the PUS piezoelectric element 111, the retaining dampers 1143 can adapt to the changes of the PUS piezoelectric element 111, so that the PUS piezoelectric element 111 is always limited by the retaining dampers 1143, avoiding the PUS piezoelectric element 111 from ineffective expansion and contraction, improving the displacement accuracy of the AF drive plate 109, and improving the working stability of the PUS piezoelectric element 111.

[0032] Furthermore, the limiting retainer 114 also includes a pressure spring 1142, which is mounted on the limiting frame 1141 and is used to apply pressure to the end of the PUS piezoelectric element 111, causing the protrusion 110 to abut against the AF drive plate 109.

[0033] The spring force of the pressure spring 1142 causes the PUS piezoelectric element 111 and the protrusion 110 to have a tendency to move laterally, thereby contacting the AF drive plate 109. After the PUS piezoelectric element 111 is de-energized, sufficient pressure is used to ensure that the friction force can maintain the position of the lens bracket 102 and the lens.

[0034] Furthermore, the limiting and retaining unit also includes a limiting plate 115, which is installed on both sides of the limiting and retaining member 114 to limit the non-deformation side of the PUS piezoelectric element 111.

[0035] The limiting plate 115 is used to ensure that the PUS piezoelectric element 111 will not detach from the limiting retainer 114, thereby improving the working stability of the PUS piezoelectric element 111.

[0036] The other parts of this embodiment are the same as those in the above embodiments, and will not be described again. Example 3:

[0037] This embodiment further expands the boot system based on the above embodiments, specifically as follows: Figures 2-4 As shown, the guidance system includes a guidance unit and a stabilization unit, both of which are disposed between the base 101 and the lens bracket 102.

[0038] Furthermore, the lens bracket 102 is provided with a guide shaft arm 103 and an AF drive arm 107. Both the guide shaft arm 103 and the AF drive arm 107 are provided with sliding grooves. The base 101 also has matching sliding grooves corresponding to the guide shaft arm 103 and the AF drive arm 107. The guiding unit includes AF guide balls 108 and AF guide rails 106. The AF guide rails 106 are installed in the sliding grooves of the guide shaft arm 103, and multiple AF guide balls 108 are installed in the sliding grooves of the AF drive arm 107. The AF guide rails 106 and AF guide balls 108 convert the sliding friction between the base 101 and the lens bracket 102 into rolling friction, reducing the movement resistance of the lens bracket 102. Simultaneously, the AF guide rails 106 and AF guide balls 108 support the lens bracket 102, improving the reliability of its movement.

[0039] Furthermore, the stabilization unit includes a magnetic adsorption block 104 and an adsorption magnet 105. The magnetic adsorption block 104 is mounted on the guide shaft arm 103, and the adsorption magnet 105 is mounted on the base 101. The magnetic adsorption block 104 and the adsorption magnet 105 cooperate with each other.

[0040] By utilizing the magnetic attraction between the magnetic adsorption block 104 and the adsorption magnet 105, the position and movement of the lens bracket 102 are stabilized.

[0041] When the lens bracket 102 is in position, if it is subjected to external impact or vibration, the lens bracket 102 can be stably maintained due to the combined forces of the friction between the AF drive plate 109 and the PUS piezoelectric element 111, the lateral pressure at the guide shaft arm 103, and the magnetic attraction of the magnetic adsorption block 104 and the adsorption magnet 105.

[0042] The other parts of this embodiment are the same as those in the above embodiments, and will not be described again.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An autofocus actuator, characterized in that, include: Base (101) for accommodating lens mount (102); The lens bracket (102) is provided with a lens mounting hole for mounting a lens module; A guiding system is used to guide the lens holder (102) to slide along the lens axis in the base (101) to achieve focusing; The drive system provides driving force for the movement of the lens bracket (102); the drive system includes a drive unit, a limit holding unit, and a control feedback unit; the limit holding unit is mounted on the base (101), the drive unit and the control feedback unit are mounted on the limit holding unit, the limit holding unit is used to limit the drive unit, and the control feedback unit is used to control the power supply of the drive unit and acquire the movement information of the lens bracket (102).

2. The autofocus actuator according to claim 1, characterized in that: The drive unit includes an AF drive plate (109), a protrusion (110), and a PUS piezoelectric element (111). The protrusion (110) is mounted on the end of the PUS piezoelectric element (111), and the AF drive plate (109) is mounted on the lens bracket (102). The AF drive plate (109) abuts against the protrusion (110).

3. An autofocus actuator according to claim 2, characterized in that: The control feedback unit includes an AF sensor magnet (112) and a Hall / FPC (113). The AF sensor magnet (112) is mounted on the lens bracket (102), and the Hall / FPC (113) is mounted on the limiting and holding unit and electrically connected to the PUS piezoelectric element (111). The Hall / FPC (113) cooperates with the AF sensor magnet (112).

4. An autofocus actuator according to claim 3, characterized in that: The limiting and retaining unit includes a limiting and retaining member (114), which is mounted on the base (101). The limiting and retaining member (114) includes a limiting frame (1141) and a retaining damper (1143). The retaining damper (1143) is mounted on the limiting frame (1141) and is used to limit and retain the deformation side of the PUS piezoelectric element (111). Both ends of the limiting frame (1141) are provided with receiving openings (1144), and the PUS piezoelectric element (111) is placed in the receiving openings (1144).

5. An autofocus actuator according to claim 4, characterized in that: The limiting retainer (114) also includes a pressure spring (1142) mounted on the limiting frame (1141) for applying pressure to the end of the PUS piezoelectric element (111) to drive the protrusion (110) to abut against the AF drive plate (109).

6. An autofocus actuator according to claim 5, characterized in that: The limiting and retaining unit also includes a limiting plate (115), which is installed on both sides of the limiting and retaining member (114) to limit the non-deformation side of the PUS piezoelectric element (111).

7. An autofocus actuator according to any one of claims 1-6, characterized in that: The guidance system includes a guidance unit and a stabilization unit, both of which are located between the base (101) and the lens bracket (102).

8. An autofocus actuator according to claim 7, characterized in that: The lens bracket (102) is provided with a guide shaft arm (103) and an AF drive arm (107). Both the guide shaft arm (103) and the AF drive arm (107) are provided with sliding grooves. The base (101) is also provided with matching sliding grooves at the corresponding locations of the guide shaft arm (103) and the AF drive arm (107). The guide unit includes an AF guide ball (108) and an AF guide rail (106). The AF guide rail (106) is installed in the sliding groove at the guide shaft arm (103), and multiple AF guide balls (108) are installed in the sliding groove at the AF drive arm (107).

9. An autofocus actuator according to claim 8, characterized in that: The stabilization unit includes a magnetic adsorption block (104) and an adsorption magnet (105). The magnetic adsorption block (104) is mounted on the guide shaft arm (103), and the adsorption magnet (105) is mounted on the base (101). The magnetic adsorption block (104) and the adsorption magnet (105) cooperate with each other.

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