KR102077849B1 - Camera module and method for auto focusing the same - Google Patents

Abstract

The present invention relates to a camera module and an auto focusing method thereof.
That is, the camera module of the present invention includes an actuator for moving the mover including at least one lens that enters the optical image of the subject; In order to drive the mover in the forward or reverse direction, including an actuator driver for controlling the actuator, defining a search section for driving the mover in the forward direction as a first search section, and a search section for driving the mover in the reverse direction When defined as a second search period, the first search period or the second search period is included.

Description

Camera module and its auto focusing method {CAMERA MODULE AND METHOD FOR AUTO FOCUSING THE SAME}

The present invention relates to a camera module and an auto focusing method thereof.

Recently, mobile phones and tablet PCs with a small camera module are being developed.

In the case of a digital camera module applied to a conventional mobile phone, the distance between an image sensor and a lens for changing external light into a digital image or a digital image cannot be adjusted, but a voice coil motor for controlling a distance between an image sensor and a lens is recently used. The same lens driving device has been developed so that the camera module can obtain an improved digital image or digital image.

In general, a voice coil motor applied to a camera module adjusts a distance between a lens-mounted mover from a base to an upper side and an image sensor disposed at a rear surface of the lens.

The conventional voice coil motor has a structure in which the elastic member contacts the base by pressing the mover when no driving signal is applied.

That is, in the conventional voice coil motor, since the elastic member presses the mover, the electromagnetic force for driving the mover must be greater than the elastic force of the elastic member and the weight of the mover in order for the mover to be spaced apart from the base.

In addition, the mover of the conventional voice coil motor has a displacement of about 30 μm to 50 μm depending on the attitude of the voice coil motor.

However, since the mover of the conventional voice coil motor has a displacement according to the attitude of the voice coil motor and includes an undriven section which is not driven even when a driving signal is applied, the mover is driven by an auto focusing algorithm that does not reflect this. Has a time-consuming problem.

The present invention is to solve the problem that can reduce the current consumption of the camera module, and can simplify the algorithm for driving the actuator.

The present invention,

An actuator for moving the mover including at least one lens incident on the optical image of the subject;

An actuator driver for controlling the actuator to drive the mover in the forward or reverse direction,

When a search section for driving the mover in the forward direction is defined as a first search section, and a search section for driving the mover in the reverse direction is defined as a second search section, includes the first search section or the second search section. A camera module is provided.

In an embodiment of the present invention, half may be allocated to drive the first search period, and the other half may be allocated to drive the second search period.

The first search period and the second search period may be symmetrical.

In addition, the first search period and the second search period may be asymmetric.

In addition, the least significant bit allocated between the first search period and the second search period may be in the range of 300 to 500 least significant bits.

In addition, the least significant bit allocated between the first search period and the second search period may be within a 500 to 1000 least significant bit range.

In addition, the actuator may be one of a voice coil motor (VCM) actuator, an actuator driven by a piezoelectric force, and a MEMS actuator driven by a capacitive type.

In addition, a posture detection unit for detecting the posture of the mover and outputting posture data; The electronic device may further include a controller configured to output a control signal to the actuator driver using the posture data output from the posture detector.

In addition, the posture of the mover may be one of an up posture, a side posture and a down posture of the lens.

The actuator includes: a mover including the lens and having a first driving part formed therein; A stator having a second driving unit for driving the mover by an electromagnetic force with the first driving unit; A base for fixing the stator and performing a lower stopper function to stop the mover; It may include a cover for performing an upper stopper function for stopping the mover.

The mover may also be spaced apart from the cover and the base.

The first driver may be a wound coil, the second driver may be a magnet, or the first driver may be a magnet, and the second driver may be a wound coil.

In addition, the actuator may further include an elastic member having one side fixed to the mover and the other side facing the one side fixed to the stator to elastically support the mover.

The present invention,

Moving the mover including the lens to infinity or macro;

Searching for the best focusing point by starting the mover in the infinity or the macro;

There is provided an auto focusing method of a camera module including performing focusing to the found best focusing point.

The present invention,

Moving the mover including the lens to perform a first search;

Determining, by the first search, whether an increase in focusing value is in an infinity direction or a macro direction;

Searching for a best focusing point by moving the mover to infinity when the focusing value increases in the infinity direction;

There is provided an auto focusing method of a camera module including performing focusing to the found best focusing point.

According to an embodiment of the present invention, when the focusing value increases in the macro direction in the step of determining whether an increase in a focusing value is an infinity direction or a macro direction in the first search, Searching for the best focusing point may be performed by moving the mover to the macro.

In addition, the first movement in the infinity direction or the macro direction may include a function of lowering the mechanical impact sound for a longer time than the other steps.

In addition, it may include a function to lower the mechanical impact sound by dividing the step size moving in the infinity direction or the macro direction in the first direction in several steps.

The present invention has the effect of detecting a posture of a voice coil motor or a lens and controlling the voice coil motor with the posture data to reduce the current consumption and to drive the camera module with optimization.

In addition, the present invention can specify a current value for each gig address by allocating a search section capable of driving in the forward and reverse directions from the bit, including the direction bits in the forward and reverse directions, thereby simplifying an algorithm for driving the actuator. It has an effect.

In addition, the present invention has the effect that can solve the defocus problem by applying the current in the opposite direction even if the spring changes, so that the mover can be driven in both directions.

1 is a block diagram illustrating a camera module according to an embodiment of the present invention.
2 is a conceptual cross-sectional view for explaining that the lens of the camera module according to an embodiment of the present invention is located in the upward direction.
3 is a conceptual cross-sectional view for explaining that the lens of the camera module according to an embodiment of the present invention is located in the lateral direction.
4 is a conceptual cross-sectional view for explaining that the lens of the camera module according to an embodiment of the present invention is located in the lower direction.
5 is a graph showing the current-distance characteristics of the camera module according to an embodiment of the present invention
6 is a flowchart of an auto focusing method of a camera module according to a first embodiment of the present invention;
7 is a flowchart of an auto focusing method of a camera module according to a second embodiment of the present invention;

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, the terms and configurations specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. Definitions of these terms should be made based on the contents throughout the specification.

1 is a block diagram of a camera module according to an embodiment of the present invention.

The camera module according to an embodiment of the present invention includes an actuator 200 for moving a mover including at least one lens that enters an optical image of a subject; In order to drive the mover in both directions, it comprises an actuator driver 210 for controlling the actuator (200).

Here, the actuator driver 210 controls the actuator 200 to drive the mover in the forward or reverse direction.

In addition, when a search section for driving the mover in the forward direction is defined as a first search section and a search section for driving the mover in the reverse direction is defined as a second search section, the first search section or the second search section. It may include.

A half may be allocated to drive the first search period, and the other half may be allocated to drive the second search period.

For example, a least significant bit (LSB) allocated to drive the first search period and the second search period may be 0 to 1023.

In this case, the least significant bit allocated to drive the first search period may be 0 to 513, and the least significant bit allocated to drive the second search period may be 513 to 1023.

In addition, the first search period and the second search period may be symmetrical or asymmetrical.

In addition, the least significant bit allocated between the first search period and the second search period may be within a range of 300 to 500 least significant bits.

In addition, the least significant bit allocated between the first search period and the second search period may be within a 500 to 1000 least significant bit range.

Therefore, the present invention can specify the current value for each address by adding the direction bits in the forward and reverse directions, allocating a search section capable of driving in the forward and reverse directions from 0-1023 least significant bit (LSB). Therefore, there is no need to know whether the actuator should be moved in the reverse direction or in the forward direction. Therefore, there is an advantage to simplify the algorithm for driving the actuator.

On the other hand, the camera module according to an embodiment of the present invention, as shown in Figure 1, the posture detection unit 230 for detecting the posture of the mover and outputting posture data; The controller 220 may further include a controller 220 outputting a control signal to the actuator driver 210 using the posture data output from the posture detector 230.

That is, the posture detection unit 230 detects the posture of the mover and outputs posture data, and the controller 220 receives posture data from the posture detection unit 230 and corresponds to the posture of the mover. The control signal is output to the actuator driver 210, and the actuator driver 210 drives the actuator 200 to suit the posture of the mover.

In this case, the posture of the mover may be one of an up posture, a side posture and a down posture of the lens, as described below.

Here, the posture detecting unit 230 may sense three or more postures of the lens, but in one embodiment of the present invention, the posture detecting unit 230 is an up posture and a side of the lens. ) Will be described for sensing the three postures, posture and down (posture).

The actuator 200 may be one of a voice coil motor (VCM) actuator, an actuator driven by a piezoelectric force, and a MEMS actuator driven by a capacitive type.

For example, the voice coil motor drives the mover by electromagnetic force to perform auto focusing of the camera module.

In addition, the posture detection unit 230 may include a gyro sensor that detects the direction of gravity.

2 is a conceptual cross-sectional view for explaining that the lens of the camera module according to an embodiment of the present invention is located in the upper direction, and FIG. 4 is a conceptual cross-sectional view for explaining that the lens of the camera module according to an embodiment of the present invention is located in the downward direction.

As described above, FIG. 2 shows an up position in which the lens of the camera module is located in an upward direction, and an "up position" denotes the lens 135 of the mover 130 of the voice coil motor. The optical axis may be defined in a direction perpendicular to the ground, and may be defined as a posture in which the base 110 is disposed to face the ground.

3 shows a side pose in which the lens of the camera module is located in the lateral direction, and the "side pose" indicates that the optical axis of the lens 135 of the mover 130 of the voice coil motor is grounded. It may be defined as a posture formed in a direction parallel to the base 110 is disposed perpendicular to the ground.

In addition, FIG. 4 illustrates a down attitude in which the lens of the camera module is located in a downward direction, and a "down attitude" denotes a lens 135 of the mover 130 of the voice coil motor 100. The optical axis may be defined in a direction perpendicular to the ground and the cover 150 may be defined as a posture facing the ground.

2 to 4, the voice coil motor 100 is applied as an actuator, and the mover 130, the stator 120, the base 110, the elastic member 140, and the cover 150 are voice motor coils. It may be a part of 100.

Referring to FIG. 2, the voice coil motor 100 drives the mover 130 in a forward or reverse direction to perform an auto focusing function.

For example, the mover 130 mounted on the voice coil motor 100 is driven in a forward direction ascending to the cover 150 or in a reverse direction descending to the base 110 and in this process the lens ( 135) and a focusing operation is performed between the image sensor 500.

That is, the mover 130 is spaced apart from the cover 150 and the base 110.

The base 110 is formed in a plate shape in which an opening through which light passes is formed in the center, and the base 110 serves as a lower stopper of the mover 130.

In addition, the image sensor 500 may be disposed at the rear of the base 110 or the rear of the base 110. The image sensor 500 converts the light focused through the lens of the mover 130 into a digital image or a moving image.

In addition, the stator 120 is fixed on the base 110.

Here, the first driver 138 may be a magnet, and the second driver 125 may be a wound coil.

On the contrary, the first driver 138 may be a wound coil, and the second driver 125 may be a magnet.

In addition, an accommodating space may be formed inside the stator 120, and the movable element 130 may be located in the accommodating space.

In addition, one side of the elastic member 140 is fixed to the mover 130 and the other side facing the one side is fixed to the stator 120, the elastic member 140 is elastic to the movable member 130 I can support it.

In one embodiment of the present invention, the elastic member 140 is the first elastic member 143 formed on the lower end of the outer peripheral surface of the mover 130 and the second elastic member (formed on the upper end of the outer peripheral surface of the mover 130 ( 146).

The cover 150 is fixed to the base 110, and the cover 150 surrounds the stator 120 and the mover 130. In addition, the cover 150 serves as an upper stopper for stopping the mover 130.

Therefore, the present invention has the effect that the defocus problem can be solved by applying a current in the opposite direction even if a change of the spring occurs because the mover can be driven in both directions.

5 is a graph showing the current-distance characteristics of the camera module according to an embodiment of the present invention.

In the camera module according to an embodiment of the present invention, the least significant bit allocated to drive the first search section in which the mover including the lens is driven in the reverse direction (−) is 0 to 513, and the mover is moved in the positive direction (+). The least significant bit allocated to drive the driven second search period is 513 to 1023.

Here, the number of bits allocated in the reverse direction may increase or decrease according to the reverse stroke or the current value.

When the least significant bit is 0, the current value is -50 mA, when the least significant bit is 513, the current value is 0 mA, and when the least significant bit is 1023, the current value can be +50 mA.

6 is a flowchart of an auto focusing method of a camera module according to a first embodiment of the present invention, and FIG. 7 is a flowchart of an auto focusing method of a camera module according to a second embodiment of the present invention.

In the auto focusing method of the camera module according to the first embodiment, as shown in FIG. 6, first, the mover including the lens is moved to infinity or macro (step S100).

Next, in the infinity or the macro, starting the mover movement to search for the best focusing point (step S110).

Here, in step S100, when the mover moves to the infinity, the mover moves from the infinity to the macro to search for the best focusing point, and when the mover moves to the macro, the infinity in the macro Move the mover to find the best focusing point.

The first and second steps of searching for the best focusing point may incline or divide the steps so that the camera module may lower the mechanical impact of the upper or lower stopper.

Subsequently, focusing is performed to the found best focusing point (S120).

In the auto focusing method of the camera module according to the second embodiment, as shown in FIG. 7, the first search is performed by moving the mover including the lens (step S200).

Next, in the first search, it is determined whether an increase in focusing value is in an infinity direction or a macro direction (step S210).

Thereafter, when the focusing value increases in the infinity direction, the mover is moved to the infinity to search for the best focusing point (step S220).

Here, in step S210, when the focusing value increases in the macro direction, the mover is moved to the macro to search for the best focusing point (step S230).

Next, focusing is performed to the found best focusing point (S240).

Here, the first movement in the infinity direction or the macro direction may include a function of lowering the mechanical impact sound for a longer time than the other steps.

In addition, a function of lowering mechanical impact sound may be included by dividing the step size moving in the infinity direction or the macro direction in the first direction into several steps.

Although embodiments according to the present invention have been described above, these are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments of the present invention are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the following claims.

Claims (22)

Base;
A cover fixed to the base;
A mover disposed in the cover;
An elastic member coupled to the mover;
An actuator including a coil disposed on the mover and a magnet facing the coil; And
An actuator driver for controlling the actuator to drive the mover in the forward or reverse direction,
The actuator is spaced apart from the cover and the first gap and spaced apart from the base and the second gap while no current is applied to the actuator,
The actuator driver is assigned a direction bit,
The direction bit includes forward movement information that the mover moves toward the cover to reduce the first gap or reverse movement information that the mover moves toward the base to reduce the second gap,
When a current is applied to the actuator in a state where no current is applied and the mover moves in the forward direction or the reverse direction, the time taken to reach the infinity position or the macro position for the first time is later than the time consumed when the mover moves. Long distance camera module. Base;
A cover fixed to the base;
A mover disposed in the cover;
An elastic member coupled to the mover;
An actuator including a coil disposed on the mover and a magnet facing the coil; And
An actuator driver for controlling the actuator to drive the mover in the forward or reverse direction,
The actuator is spaced apart from the cover and the first gap and spaced apart from the base and the second gap while no current is applied to the actuator,
The actuator driver is assigned a direction bit,
The direction bit is assigned to a forward bit that causes the mover to move toward the cover to reduce the first gap or a reverse bit that causes the mover to move toward the base to reduce the second gap,
When a current is applied to the actuator in a state where no current is applied and the mover moves in the forward direction or the reverse direction, the time taken to reach the infinity position or the macro position for the first time is later than the time consumed when the mover moves. Long distance camera module. delete The method according to claim 1 or 2,
A mechanical impact sound between the mover and the base or the mover and the cover is reduced as the time for which the mover first reaches the infinity position or the macro position increases. The method according to claim 1 or 2,
When the current is applied to the actuator with no current applied and the mover moves in the forward or reverse direction, the mechanical impact sound is reduced by dividing the step size into a plurality of stages until the first infinity or macro position is reached. Camera module. The method according to claim 1 or 2,
And a first search section that is a search section for moving the mover in the forward direction, and a second search section that is a search section for moving the mover in the reverse direction. The method of claim 6,
A half is allocated to drive the first search period, and the other half is allocated to drive the second search period. The method of claim 6,
The first search section and the second search section symmetrical camera module. The method of claim 6,
The first search section and the second search section is asymmetrical camera module. The method of claim 6,
The least significant bit allocated between the first search period and the second search period is within a range of 300 to 500 least significant bits. The method of claim 6,
The least significant bit allocated between the first search period and the second search period is in the range of 500 to 1000 least significant bits. The method according to claim 1 or 2,
A posture detector for detecting posture of the mover and outputting posture data; And
And a controller configured to output a control signal to the actuator driver using posture data output from the posture detector. The method of claim 12,
The posture of the mover is a camera module of one of the up (up), side (down) and down (down) position of the lens. The method according to claim 1 or 2,
The base performs a lower stopper function to stop driving of the mover in the reverse direction,
And the cover performs an upper stopper function to stop driving of the mover in the forward direction. The method according to claim 1 or 2,
The elastic member is a camera module including a first elastic member coupled to the upper portion of the mover, and a second elastic member coupled to the lower portion of the mover. The method according to claim 1 or 2,
Including an image sensor,
And the mover comprises a lens disposed at a position corresponding to the image sensor. An autofocusing method of a camera module through the camera module of claim 1,
Moving the mover including the lens to infinity or macro;
Searching for a best focusing point by starting the mover of the infinity or the macro; And
And focusing by moving the mover to the found best focusing point in the step of searching for the best focusing point. An autofocusing method of a camera module through the camera module of claim 1,
Moving the mover including a lens to perform a first search;
Determining whether an increase in a focusing value by the first search is in infinity or in a macro direction;
Searching for a best focusing point by moving the mover to infinity when the focusing value increases in the infinity direction; And
And focusing by moving the mover to the found best focusing point in the step of searching for the best focusing point. The method of claim 18,
Determining whether an increase in a focusing value is an infinity direction or a macro direction by the first search;
And if the focusing value increases in the macro direction, searching for a best focusing point by moving the mover to the macro. The method of claim 18 or 19,
Auto-focusing method of the camera module including a function that the movement time when the first movement in the infinity direction or the macro direction is consumed longer than the other steps to reduce the mechanical impact sound. The method of claim 18 or 19,
Auto-focusing method of the camera module comprising a function of reducing the mechanical impact sound by dividing the step size moving in the infinity direction or the macro direction in the first direction in a plurality of steps. Cell phone comprising the camera module of claim 1.

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