KR100775828B1 - Camera module for a mobile communication device and control method thereof - Google Patents

Abstract

The present invention relates to a camera module and a control method thereof used in a mobile communication terminal. The camera module according to the present invention forms an image sensor unit for photoelectric conversion of the optical image formed by the image, the optical image of the subject to the image sensor unit, and adjusts the focus of the optical image by a movement in which the separation distance from the image sensor unit changes The lens module unit controls the movement of the lens module unit in response to the input driving signal. When the driving signal is not input, the lens module unit controls the lens module unit to be in a wide angle position, and generates and applies a driving signal to the lens driving unit. It includes a camera control unit. According to the present invention, it is possible to reduce the power consumed for providing the autofocus control function in the camera module.

Camera Module, VCM, Voice Coil, Mobile Communication Terminal

Description

Camera module for a mobile communication terminal and control method thereof

1 is a block diagram of an example of a mobile communication terminal having a camera module according to the present invention;

2 is a block diagram of a camera module according to an embodiment of the present invention;

3 is a flow chart provided in the description of the control method of the camera module according to an embodiment of the present invention, and

4 is a view referred to in the description of the control method of the camera module in an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

130: camera module unit 131: lens module unit

133: image sensor unit 135: signal processing unit

137: lens driving unit 139: camera control unit

The present invention relates to a camera module and a control method thereof, and more particularly, to a camera module used for a mobile communication terminal and the control method provided with an autofocus control function by a voice coil motor method.

With the expansion of digital convergence, mobile communication terminals such as mobile phones and personal digital assistants are evolving into multimedia complex devices rather than simple communication devices. Accordingly, additional functions such as digital cameras, camcorders, MP3 players, game machines, and TVs are being incorporated into mobile communication terminals. In particular, as the proportion of mobile communication terminals having digital camera functions in the overall mobile communication terminal market increases, the importance of camera-only parts such as camera modules is also increasing.

The camera module broadly includes a compact camera module (CCM) and all components used in various electronic devices such as a personal digital assistant (PDA), a PC camera, a small surveillance camera, and a robot's artificial vision. Among the camera modules, in the case of a high pixel camera module used in a mobile communication terminal, a lens driving unit for moving a lens module composed of one or a plurality of lenses in order to implement an optical zoom and an auto focus adjustment function. need. There are many ways to implement the lens driver for optical zoom and autofocus in the camera module. However, there are a large number of stepping motor, piezo motor, hydraulic lens, and voice coil. It can be classified into a motor type and the like.

Among these, the voice coil motor system is a system in which a magnet and a coil are disposed around the lens barrel and the lens module is directly moved back and forth in accordance with the direction of the current applied to the coil. In order to realize the autofocus control function in the camera module, the lens module needs to be moved while moving about 0.3mm, and the voice coil motor method can realize this in a small volume. Therefore, the voice coil motor system is excellent in volume and cost, and is suitable for mounting to a mobile communication terminal. However, in order to maintain the position of the lens module moved to maintain the focal length, since the current must be continuously applied to the voice coil motor, power consumption is relatively large.

However, minimizing power consumption in a mobile device such as a mobile communication terminal is an important problem. Therefore, when the camera module using the voice coil motor method is mounted in the mobile communication terminal, a method of minimizing the power consumption accordingly is possible. This should be considered.

Accordingly, an object of the present invention is to provide a camera module and a control method thereof that can minimize power consumption when implementing an autofocus control function to be suitable for use in a mobile communication terminal.

The camera module according to the present invention for achieving the above object, the image sensor unit for photoelectric conversion of the optical image formed, the image of the optical image of the subject to the image sensor unit, the moving distance is changed from the image sensor unit The lens module unit adjusts the focus of the optical image, and controls the movement of the lens module unit in response to an input driving signal, and when the driving signal is not input, the initial position corresponding to the wide-angle position. A lens driving unit controlling the lens driving unit, and generating the driving signal when the close-up of the subject is photographed, and applying the driving signal to the lens driving unit; It includes a camera control unit for blocking the signal.

Preferably, the lens driving unit controls the movement of the lens module unit by using a voice coil motor, and the driving signal is a signal corresponding to a current applied to the voice coil motor.

The camera controller may generate the driving signal to enable automatic focus adjustment based on the analysis of the frequency component of the signal output from the image sensor unit.

On the other hand, the control method of the camera module according to the present invention, the optical image of the subject to the image sensor, the lens module unit for adjusting the focus of the optical image by the movement of the distance to the image sensor changes, and the input In the camera module having a lens driving unit for controlling the movement of the lens module unit in response to the driving signal is set, when the driving signal is not input, setting the lens module unit to the initial position corresponding to the wide-angle position, the In the case of close-up photography of the subject, the driving signal is applied to the lens driving unit to enable automatic focus adjustment, and when the close-up photographing is terminated, the driving signal applied to the lens driving unit is blocked, and the close-up photography of the subject is performed. If not, including the step of performing the photographing of the subject without applying the drive signal .

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 is a block diagram of an example of a mobile communication terminal having a camera module according to the present invention. Referring to FIG. 1, the mobile communication terminal includes a wireless communication unit 110, a camera module unit 130, a peripheral unit 150, and a baseband processor 170.

The wireless communication unit 110 provides an interface for communicating with an external device connected to a mobile communication network, a duplexer filter for separating transmission and reception signals from an antenna, a power amplifier for amplifying a transmission signal, a frequency upconversion circuit of a transmission path, and reception. A frequency downconversion circuit of the path, and the like. The camera module 130 performs a digital camera function of photographing a subject. The peripheral unit 150 includes a keypad including a plurality of keys including numeric keys and function keys, a display unit for displaying a signal reception state and battery information of the other party during a call, and a program or data necessary for operating a mobile communication terminal. Or a memory for storing various data that the user wants to store. The baseband processor 170 controls the operation of each unit to control the overall operation of the mobile communication terminal. In particular, the baseband processor 170 controls baseband signal processing and call processing after the wireless communication unit 110.

In such a configuration, when the camera mode is selected by the user, the camera module 130 transmits image data photographing a subject to the baseband processor 170, and the baseband processor 170 stores the same in the memory. In this case, it can be used for various purposes according to the user's choice.

2 is a block diagram of a camera module according to an embodiment of the present invention. 2, the camera module 130 is a lens module unit 131. An image sensor unit 133, a signal processor 135, a lens driver 137, and a camera controller 139 are included.

The lens module unit 131 includes one or a plurality of lenses and forms an optical image of the subject on the image sensor unit 133 through the provided lens. The image sensor unit 133 uses a charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS), or the like to photoelectrically change an optical image formed through the lens module unit 131 to output an electrical signal. The signal processor 135 processes the electrical signal output from the image sensor 133 to generate image data corresponding to the image of the photographed subject.

The lens driving unit 137 moves the lens module unit 131 by using a voice coil motor method, and accordingly, the separation distance between the lens module unit 131 and the image sensor unit 133 is changed, and thus the image sensor unit ( 133) to adjust the focus of the optical image forming. In this case, the lens driver 137 moves the lens module 131 in response to a driving signal output from the camera controller 139. The camera controller 139 controls the operation of each unit, and in particular, outputs a driving signal to the lens driver 137 to provide an autofocus control function.

In such a configuration, the camera module according to an embodiment of the present invention is configured as follows to be suitable for use in a mobile communication terminal. That is, when the camera module is manufactured, a case in which a driving signal is not input to the lens driver 137 is set as a default, and the initial position of the lens module 131 is located at a long distance, that is, at a wide angle position.

As a result, when a driving signal is not applied to the lens driver 137, the lens module 131 is focused at a wide angle position. At this time, the focal length is about 1.2m, so that it is suitable for shooting portraits or landscapes that are slightly separated like a general fixed focus lens. In addition, during close-up photography, the autofocus control function is implemented to take a picture by applying a driving signal to the lens driving unit 137 to move the lens module unit 131, and after taking the picture, the lens driving unit 137. When the driving signal applied to the) is blocked, the lens module unit 131 moves to the wide angle position, which is the initial position.

3 is a flowchart provided to explain a control method of a camera module according to an embodiment of the present invention. 2 and 3, the control method of the camera module according to an embodiment of the present invention will be described. First, when the camera mode is selected, the camera module mounted in the mobile communication terminal starts operation (S205). If it is not the camera mode, the operation according to the selected corresponding mode is executed (S240).

When the camera mode is selected, it is determined whether it is a close-up shot (S210), and when the result of the determination is a close-up shot, the voice coil motor of the lens driver 137 is driven to adjust the focus (S215). In this case, the movement distance of the lens module unit 131 is determined by a driving signal transmitted from the camera controller 139 to the lens driver 137. The camera controller 139 detects a distance by returning light or ultrasonic waves to a subject, or analyzes frequency components of a signal output from the image sensor 133 to generate a corresponding driving signal to provide an autofocus control function. Output to the lens driver 137.

A macro mode is generally required for close-up photography, and as shown in FIG. 4, the distance between the lens module unit 131 and the image sensor unit 133 should be increased. That is, if (a) of FIG. 4 illustrates the initial position of the lens module unit 131, the autofocus control should be performed when the lens module unit 131 is moved in the direction of the arrow as shown in FIG. Function may be provided. At this time, the movement amount of the lens module unit 131 is about 0.3 mm.

When the focus is adjusted by the movement of the lens module unit 131, photographing is performed (S220). When shooting is finished (S225), the driving signal applied to the lens driver 137 is blocked to stop driving of the voice coil motor in the lens driver 137 (S230). As a result, the lens module 131 is again positioned at the wide-angle position, which is the initial position, as shown in FIG. If, as a result of the determination in step S210, when not near-field shooting, the photographing is performed without moving the lens module unit 131.

When the camera module is controlled by the above process, since the lens module unit 131 maintains the focus at the wide angle position again after the shooting is completed, the current consumed by the voice coil motor for the autofocus control function is measured in close-up, That is, it will be used for a while only in macro mode. However, since the frequency of continuous shooting at a short distance in a mobile communication terminal or the like is very low, it is possible to reduce the current consumption used to provide an autofocus control function in the camera module.

Meanwhile, in the above-described embodiment, the case in which the camera module according to the present invention uses the voice coil motor method has been described as an example, but the control method of the camera module according to the present invention includes an actuator for implementing an autofocus control function. This is applicable to a device in which a focal distance is maintained only by maintaining a current, such as when the lens is moved while the length of the alloying material changes according to the current. In addition to the automatic focusing function, it is possible to apply both when the lens module unit needs to be moved, such as optical zoom.

In addition, while the above has been shown and described with respect to preferred embodiments of the present invention, the present invention is not limited to the specific embodiments described above, the technology to which the invention belongs without departing from the spirit of the invention claimed in the claims Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

As described above, according to the present invention, the initial position at which the voice coil motor is not driven is set to the wide angle position, and the voice coil motor is driven only during close-up photography, thereby reducing the current consumption for providing the autofocus control function. Can be. Therefore, when the camera module is used in a mobile communication terminal or the like, the total power consumption is reduced to allow a long time use.

Claims (9)

An image sensor unit for photoelectrically converting the formed optical image; A lens module unit configured to form an optical image of a subject on the image sensor unit and to adjust the focus of the optical image by a movement in which a distance between the image sensor unit and the image sensor unit is changed; A lens driver for controlling movement of the lens module unit in response to an input driving signal, and controlling the lens module unit to be in an initial position corresponding to a wide-angle position when the driving signal is not input; And A camera control unit which generates the driving signal when the close-up of the subject is photographed and applies the driving signal to the lens driving unit, and controls the driving signal not to be applied to the lens driving unit when the close-up of the subject is finished and when the close-up of the subject is not close-up; Camera module comprising a. The method of claim 1, The lens driver, the camera module, characterized in that for controlling the movement of the lens module unit using a voice coil motor. The method of claim 2, The driving signal is a camera module, characterized in that the signal corresponding to the current applied to the voice coil motor. The method of claim 1, And the camera controller generates the driving signal to enable auto focus adjustment based on the analysis of the frequency component of the signal output from the image sensor unit. delete A mobile communication terminal comprising the camera module of claim 1 to photograph a subject. The optical image of the subject is imaged on the image sensor, and the lens module unit adjusts the focus of the optical image by the movement of changing the separation distance from the image sensor, and controls the movement of the lens module unit in response to an input driving signal. In the control method of the camera module having a lens driving unit, Setting the lens module unit to be at an initial position corresponding to a wide-angle position when the driving signal is not input; Applying the driving signal to the lens driving unit to enable automatic focus adjustment when the subject is in close-up photography, and blocking the driving signal applied to the lens driving unit at the end of the close-up photography; And And when the photographing of the subject is not in close-up, performing the photographing of the subject without applying the driving signal. delete The method of claim 7, wherein The driving signal is a control method of a camera module, characterized in that for generating an autofocus control based on the analysis of the frequency component of the signal output from the image sensor.

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