KR102327732B1 - Actuator driving apparatus and camera module including the same - Google Patents

Abstract

An actuator driving apparatus according to an embodiment of the present invention includes: a sensing unit for applying a reference signal to a driving coil of an actuator and detecting a coil current flowing through the driving coil; a determination unit for determining the position of the lens carrier according to the coil current; and a driving unit for driving the actuator according to the position of the lens carrier and the position control signal.

Description

Actuator driving device and camera module including the same

The present invention relates to an actuator driving device and a camera module including the same.

In general, a camera module mounted in an electronic device includes a lens barrel having a lens therein, a lens carrier having a lens barrel, and a housing accommodating the lens carrier therein, and converting an image of a subject into an electrical signal. includes a sensor. In addition, as the camera module, a single-focal camera module for photographing an object with a fixed focus may be employed. . In addition, the camera module may include an actuator for optical image stabilization (OIS) in order to reduce resolution degradation caused by hand shake.

An actuator driving device is used to drive the above-described actuator, and the actuator driving device detects the position of the lens carrier and drives the actuator to move the lens carrier to a target position according to the position and position control signal of the lens carrier.

For reference, there is Patent Document 1 as a prior art related to the present invention.

Republic of Korea Patent Publication No. 2013-0077216

According to an embodiment of the present invention, there is provided an actuator driving device and a camera module including the same, which enable accurate actuator driving by determining the position of a lens carrier according to a change in a coil current flowing in a driving coil.

In order to solve the problems of the present invention described above, an actuator driving apparatus according to an embodiment of the present invention includes: a sensing unit for applying a reference signal to a driving coil of an actuator and detecting a coil current flowing through the driving coil; a determination unit for determining the position of the lens carrier according to the coil current; and a driving unit for driving the actuator according to the position of the lens carrier and the position control signal.

In addition, the camera module according to an embodiment of the present invention is mounted on the housing and the lens carrier to which a magnetic material is attached; an actuator including a driving coil disposed on the housing to face the magnetic body, and receiving a driving signal to move the lens carrier; and an actuator driving device for driving the actuator, wherein the actuator driving device applies a reference signal to the driving coil and detects a coil current flowing through the driving coil. It may include a determining unit for determining, and a driving unit for driving the actuator according to the position of the lens carrier and the position control signal.

The actuator driving apparatus and the camera module including the same according to an embodiment of the present invention may determine the position of the lens carrier according to a change in the coil current flowing through the driving coil.

In addition, since a separate position sensor is not required, cost can be reduced and space efficiency is improved.

1 is an exploded perspective view of a camera module including an actuator driving device according to an embodiment of the present invention.
FIG. 2 is a combined perspective view of a camera module according to an embodiment of the present invention shown in FIG. 1 .
3 is a cross-sectional view of a camera module according to an embodiment of the present invention shown in FIG. 1 .
4A and 4B are schematic external views of an electronic device including a camera module according to an embodiment of the present invention.
5 is a block diagram illustrating an actuator driving apparatus according to an embodiment of the present invention.
6 is a waveform diagram illustrating a control signal and a reference signal according to an embodiment of the present invention.
7 is a waveform diagram illustrating a reference signal and a coil current according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided in order to more completely explain the present invention to those of ordinary skill in the art. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be embodied in other embodiments without departing from the spirit and scope of the invention.

In addition, 'including' a certain component means that other components may be further included, rather than excluding other components, unless otherwise stated.

Before describing the actuator driving device according to an embodiment of the present invention in detail, first, the structure and function of the camera module including the actuator driving device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 . do it with

1 to 3, for convenience of explanation, the camera module 100 is illustrated as including one actuator for the automatic focus control function, but may include a plurality of actuators to provide a hand shake correction function.

1 is an exploded perspective view of a camera module including an actuator driving device according to an embodiment of the present invention, and FIG. 2 is a combined perspective view of the camera module according to an embodiment of the present invention shown in FIG. 1 .

1 and 2 , the camera module 100 according to an embodiment of the present invention includes an actuator driving device 110 , an actuator 130 , a lens module 140 , and a sensor module 150 . .

The actuator driving device 110 may determine the position of the lens carrier 142 and output a control signal for driving the actuator 130 according to the position of the lens carrier 142 and a position control signal from the outside. Also, the actuator driving device 110 may be disposed on one surface of the first substrate 120 .

In FIG. 1 , the actuator driving device 110 is illustrated as being disposed in the central region of the driving coil 131 , but the position of the actuator driving device 110 may be changed.

The actuator driving device 110 may apply a reference signal to the driving coil 131 of the actuator 130 to determine the position of the lens carrier 142 and detect a coil current flowing through the driving coil 131 .

A detailed configuration and function of the actuator driving device 110 will be described later with reference to FIGS. 5 to 7 .

The actuator 130 may receive a control signal from the actuator driving device 110 to generate a driving force capable of moving the lens carrier 142 in the direction of the optical axis 1 .

To this end, the actuator 130 may include one of a rotation motor, a piezo actuator, and a voice coil motor, but is not limited thereto. Hereinafter, it is assumed that the actuator 130 includes a voice coil motor.

The actuator 130 may include a driving coil 131 and a magnetic body 132 .

The driving coil 131 may be disposed on one surface of the substrate 120 , and the substrate 120 on which the driving coil 131 is disposed may be a printed circuit board. Also, the substrate 120 may be disposed on one side of the housing 141 . For example, the driving coil 131 may be disposed along the circumference of the actuator driving device 110 .

The magnetic material 132 may face the driving coil 131 and be attached to the lens carrier 142 .

Specifically, the control signal from the actuator driving device 110 may be supplied to the driving coil 131 included in the actuator 130 to form an electric field, which interacts with the magnetic field of the magnetic body 132, A driving force for moving the lens carrier 142 in the direction of the optical axis 1 may be generated according to the left hand rule.

The magnetic material 132 may generate a driving force by reacting with a magnetic field generated when a current flows through the driving coil 131 .

In addition, the magnetic body 132 may include a first magnetic body 132a and a second magnetic body 132b. The first magnetic material 132a and the second magnetic material 132b may be formed by polarizing the magnetic material 132 , and accordingly, it may be easy to control the movement of the lens carrier 142 .

The lens module 140 includes a housing 141 accommodating a lens carrier 142 having a lens barrel 143 , and a stopper 144 and housing 141 for limiting movement along the optical axis 1 of the lens carrier 142 . ) may include a shield case 145 surrounding the.

In the lens barrel 143, at least one lens may be assembled using an adhesive or screw coupling method.

The ball bearing 146 may be disposed on the inner guide of the housing 141 to support movement along the optical axis of the lens carrier 142 through a rolling motion. In addition, the ball bearing 146 may be divided (146a, 146b) disposed on the inner guide of the housing 141 , and a lubricant may be applied to the surface of the ball bearing 146 .

The image sensor module 150 may be disposed under the housing 141 , and the image sensor module 150 may include an image sensor 151 , a flexible printed circuit 152 , and a circuit board 153 . The image sensor 151 may be disposed on the image forming surface and mounted on one surface of the circuit board 153 by wire bonding 154 . The flexible printed circuit 152 may extend from the circuit board 153 to be connected to an internal circuit of an electronic device, such as a camera or a mobile communication terminal, which will be described later. A coupling portion 156 coupled to the substrate 120 may be provided at one end of the circuit board 153 . In addition, the image sensor module 150 may further include an infrared filter 155 that filters the incident image and transmits it to the image sensor 151 .

3 is a cross-sectional view of a camera module according to an embodiment of the present invention shown in FIG. 1 .

Referring to FIG. 3 , a magnetic material 132 may be attached to one side of the lens carrier 142 accommodating the lens barrel 143 .

Also, the driving coil 131 may be disposed inside the housing 141 facing one side of the lens carrier 142 .

4A and 4B are schematic external views of an electronic device including a camera module according to an embodiment of the present invention.

As shown in FIGS. 4A and 4B , the electronic device 10 according to an embodiment of the present invention may include a camera module 100 , and the lens of the camera module 100 is a lens of the electronic device 10 . It may be opened to the outside through the opening 10b to capture an external subject.

The camera module 100 may be electrically connected to the controller 10c of the electronic device 10 to perform a control operation according to a user's selection.

Meanwhile, although not shown in FIG. 4B , the controller 10c may include an application integrated circuit (IC) that outputs a position control signal to the actuator driving device.

5 is a block diagram illustrating an actuator driving apparatus according to an embodiment of the present invention.

Referring to FIG. 5 , the actuator driving apparatus 110 according to an embodiment of the present invention may include a sensing unit 111 , a determining unit 112 , and a driving unit 113 .

The sensing unit 111 , the determining unit 112 , and the driving unit 113 may be composed of one integrated circuit or two or more integrated circuits.

The one integrated circuit may be implemented by, for example, a combination of hardware such as a microprocessor and software mounted thereon and programmed to perform a predetermined operation.

The hardware may include at least one processing unit. The processing unit may include, for example, a central processing unit (CPU), a microprocessor, an Application Specific Integrated Circuit (ASIC), Field Programmable Gate Arrays (FPGA), and the like, and may have a plurality of cores.

Hereinafter, the operation of the actuator driving apparatus 110 according to an embodiment of the present invention will be described sequentially according to the flow of a signal from the sensing unit 111 .

The sensing unit 111 may apply a reference signal S_rect to the driving coil 131 and detect a coil current flowing through the driving coil 131 (S_sens). Since the driving coil 131 is disposed to face the magnetic material 132 (FIG. 1) as described above in FIG. 1, the magnetic field of the magnetic material applied to the driving coil 131 may be changed according to a change in the position of the magnetic material. . The change in the magnetic field causes the inductance of the driving coil 131 to change, and the level of the coil current flowing through the driving coil 131 may be changed according to the change in inductance.

That is, the inductance of the driving coil may change according to the position of the lens carrier, and the level of the coil current may change.

Also, the sensing unit 111 may detect a coil current from which an offset current formed in the driving coil 131 is removed by the control signal S_ctr for driving the actuator 130 . To this end, the sensing unit 111 may receive the control signal S_ctr from the driving unit 113 .

Meanwhile, the sensing unit 111 may apply the reference signal S_rect, which is a voltage signal of a square wave, to the driving coil 131 .

The determination unit 112 may determine the position of the lens carrier 142 ( FIG. 1 ) according to the coil current, and may output position information of the lens carrier to the driving unit 113 . For example, the determination unit 112 may determine the position of the lens carrier according to the level of the coil current using mapping data pre-stored in a memory (not shown). Also, the determination unit 112 calculates the inductance based on the voltage level of the reference signal S_rect and the current level of the coil current, and outputs the position information of the lens carrier corresponding to the calculated inductance to the driver 113. have.

The memory may be configured as a non-volatile memory, and the non-volatile memory may be a flash memory, an Electrically Erasable Programmable Read-Only Memory (EEPROM), or a Ferroelectric RAM (FeRAM).

The driving unit 113 may drive the actuator according to the position information of the lens carrier and the position control signal Ap_cmd received from the determining unit 112 . Also, the position control signal Ap_cmd may be input from the application IC 200 .

For example, the position control signal Ap_cmd input to the actuator driving device 110 may include position information indicating a target position of a lens carrier that the user wants to move, that is, a target displacement of the lens carrier.

The driving unit 113 may correct the position control signal Ap_cmd by using the position of the lens carrier. Thereafter, the driving unit 115 may output a control signal S_ctr for driving the actuator according to the corrected position control signal Ap_cmd.

The driving unit 115 may include an H-bridge driver capable of bidirectional driving.

6 is a waveform diagram illustrating a control signal and a reference signal according to an embodiment of the present invention.

For example, the control signal S_ctr output from the driver 115 ( FIG. 5 ) may be a voltage signal having a step waveform. However, the present invention is not limited thereto, and the voltage signal may be converted into a current signal and input to the actuator 130 ( FIG. 5 ), and the control signal S_ctr is a ramp waveform or a linear waveform. can have

It has been described above that the actuator receiving the control signal S_ctr can generate a driving force capable of moving the position of the lens carrier 142 ( FIG. 1 ).

Referring to FIG. 6 , a reference signal S_rect that is a voltage signal of a square wave applied by the sensing unit 111 ( FIG. 5 ) to the driving coil 131 ( FIG. 5 ) is combined with a control signal S_ctr. , it can be seen that FIG. 5) is applied. Here, the reference signal S_rect may have a smaller amplitude than the voltage level of the control signal S_ctr so as to minimize an influence of the actuator on generating a driving force.

Accordingly, not only the coil current by the reference signal S_rect but also the offset current formed in the driving coil 131 by the control signal S_ctr may flow in the driving coil.

Meanwhile, the sensing unit 111 ( FIG. 5 ) may detect a coil current from which the offset current is removed.

7 is a waveform diagram illustrating a reference signal and a coil current according to an embodiment of the present invention.

Referring to FIG. 7 , a waveform in which one period of the reference signal S_rect applied by the sensing unit 111 ( FIG. 5 ) to the driving coil 131 ( FIG. 5 ) is enlarged can be confirmed. Here, the reference signal S_rect may be a square wave voltage signal.

The coil currents I_L1 and I_L2 flowing through the driving coil by the reference signal S_rect may have different waveforms according to different inductances of the driving coil.

The sensing unit 111 ( FIG. 5 ) of the actuator driving apparatus according to an embodiment of the present invention may detect the coil currents to determine the position of the lens carrier.

Meanwhile, the coil currents I_L1 and I_L2 may reach a steady state having a constant current value I_stdy within the high level section of the reference signal S_rect if the high level section is long enough.

Therefore, if the high level pulse width P_width of the reference signal S_rect is greater than the steady state arrival time T_stdy of the coil current, it may be difficult to accurately detect the coil current.

In order to accurately detect the coil current, the sensing unit may sense the coil current before the coil current flowing through the driving coil reaches a steady state.

Alternatively, a high level pulse width P_width of the reference signal S_rect may be set to be shorter than a time for which the coil current reaches a steady state.

In the above, the present invention has been described with specific matters such as specific components and limited embodiments and drawings, but these are provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, Those of ordinary skill in the art to which the present invention pertains may devise various modifications and variations from these descriptions.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and not only the claims described below but also all modifications equivalently or equivalently to the claims described below belong to the scope of the spirit of the present invention. will do it

100: camera module
110: actuator drive device
111: detection unit
112: judgment unit
113: driving unit
130: actuator
131: drive coil
140: lens module
141: housing
142: lens carrier
150: sensor module

Claims (14)

a sensing unit for detecting a coil current flowing through the driving coil of the actuator;
a determination unit for determining the position of the lens carrier according to the coil current; and
A driving unit for driving the actuator by applying a voltage signal including a control signal for driving the actuator according to the position of the lens carrier and the position control signal
including,
The determination unit is an actuator driving device for determining the position of the lens carrier based on the time the coil current corresponds to the voltage signal.
According to claim 1,
The voltage signal is an actuator driving device further comprising a reference signal of a square wave.
According to claim 1,
The sensing unit is an actuator driving device for sensing the coil current before the coil current reaches a steady state.
According to claim 1,
The driving coil is an actuator driving device in which the inductance is changed according to the position of the lens carrier.
According to claim 1,
The sensing unit is an actuator driving device for detecting the coil current by removing the offset current by the control signal.
According to claim 1,
The determination unit calculates the inductance of the driving coil according to the coil current and outputs the position information of the lens carrier corresponding to the inductance to the driving unit.
a lens carrier mounted on the housing and having a magnetic body attached thereto;
an actuator including a driving coil disposed on the housing to face the magnetic body, and receiving a control signal to move the lens carrier; and
An actuator driving device for driving the actuator,
The actuator driving device is
Detecting a coil current flowing through the driving coil, and driving the actuator by applying a voltage signal including the control signal according to the position and position control signal of the lens carrier,
The position of the lens carrier is a camera module based on the time the coil current corresponds to the voltage signal.
8. The method of claim 7,
The voltage signal is a camera module further comprising a reference signal of a square wave.
8. The method of claim 7,
The actuator driving device is a camera module for detecting the coil current before the coil current reaches a steady state.
8. The method of claim 7,
The driving coil is a camera module in which the inductance is changed according to the position of the lens carrier.
8. The method of claim 7,
The actuator driving device is a camera module for detecting a coil current from which the offset current by the control signal is removed.
8. The method of claim 7,
The actuator driving device is a camera module for calculating the inductance of the driving coil according to the coil current and processing the position information of the lens carrier corresponding to the inductance.
8. The method of claim 7,
The actuator is a camera module including a voice coil motor (VCM: Voice Coil Motor) for applying the voltage signal to the driving coil.
According to claim 1,
The actuator driving unit applies the voltage signal to the driving coil.

Images