KR20160038409A - Mobile terminal and method for controlling the same - Google Patents

Abstract

The present invention discloses a mobile terminal and a control method thereof that improve an autofocus execution speed and accuracy. A mobile terminal for this purpose includes a camera including a lens and an image sensor; A light emitting portion for emitting light; A light receiving unit for receiving reflected light when the light emitted through the light emitting unit is reflected; At least two AF (Auto Focus) sensors for receiving at least a portion of the light passing through the lens; A display unit for displaying a preview image input through the camera before photographing; And a controller for determining a focus position focused on a subject indicated by the touched position based on the time taken for the light receiving unit to receive the reflected light when the touched position on the preview image is touched, And a control unit for performing a first-order correction on the focal position based on a phase difference between the focus position and the focus position.

Description

[0001] MOBILE TERMINAL AND METHOD FOR CONTROLLING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a mobile terminal and a control method thereof that improve an autofocus execution speed and accuracy.

A terminal can be divided into a mobile / portable terminal and a stationary terminal depending on whether the terminal is movable or not. The mobile terminal can be divided into a handheld terminal and a vehicle mounted terminal according to whether the user can directly carry the mobile terminal.

The functions of mobile terminals are diversified. For example, there are data and voice communication, photographing and video shooting through a camera, voice recording, music file playback through a speaker system, and outputting an image or video on a display unit. Some terminals are equipped with an electronic game play function or a multimedia player function. In particular, modern mobile terminals can receive multicast signals that provide visual content such as broadcast and video or television programs.

Such a terminal has various functions, for example, in the form of a multimedia device having multiple functions such as photographing and photographing of a moving picture, reproduction of a music or video file, reception of a game and broadcasting, etc. .

Through the mobile terminal, the user can take an image (photograph or video) to be recorded. In this case, when the camera of the mobile terminal is activated for photographing, the mobile terminal can output a preview image of the object to be photographed by the user through the display unit. The user can predict a photograph or a moving image to be photographed later on the preview image.

At this time, if the user touches an arbitrary position of the preview image, the mobile terminal can automatically focus on the object indicated by the touched point. For autofocus focusing on a specific subject, a distance difference method, a phase difference method and a contrast difference method can be used. However, since each of these advantages and disadvantages is distinct, if any one of them is used, there may be a disadvantage that the focusing accuracy is lowered or the focusing speed is slowed down.

Accordingly, there is a demand for development of a new autofocus method that increases the focusing speed while increasing the focusing accuracy.

It is an object of the present invention to provide a mobile terminal with improved user convenience and a control method thereof.

In particular, it is an object of the present invention to provide a mobile terminal having increased autofocusing speed and accuracy.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a mobile terminal including: a camera including a lens and an image sensor; A light emitting portion for emitting light; A light receiving unit for receiving reflected light when the light emitted through the light emitting unit is reflected; At least two AF (Auto Focus) sensors for receiving at least a portion of the light passing through the lens; A display unit for displaying a preview image input through the camera before photographing; And a controller for determining a focus position focused on a subject indicated by the touched position based on the time taken for the light receiving unit to receive the reflected light when the touched position on the preview image is touched, And a control unit for performing a first-order correction on the focal position based on a phase difference between the focus position and the focus position.

According to another aspect of the present invention, a method of controlling a mobile terminal includes displaying a preview image input through a camera before photographing; Emitting light through a light emitting portion; Receiving the reflected light when the light emitted through the light emitting unit is reflected; Determining a focus position focused on a subject indicated by the touched position based on a time taken for the light receiving unit to receive the reflected light when a position on the preview image is touched; And performing a first-order correction on the focal position based on a phase difference between the AF sensors.

The present invention is not limited to the above-mentioned solving means, and other solving means which is not mentioned may be apparent from the following description to those skilled in the art to which the present invention belongs It can be understood.

Effects of the mobile terminal and the control method according to the present invention will be described as follows.

According to at least one of the embodiments of the present invention, it is possible to provide a mobile terminal that improves user convenience.

Specifically, the present invention is advantageous in that a mobile terminal having improved autofocus speed and accuracy can be provided.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

1A is a block diagram illustrating a mobile terminal according to the present invention.
1B and 1C are conceptual diagrams illustrating an example of a mobile terminal according to the present invention in different directions.
2 is a view for explaining autofocus of a distance measuring method applicable to the present invention.
FIG. 3 is a view showing another example for explaining autofocus of a distance measurement method applicable to the present invention.
4 is a view for explaining a phase difference autofocus that can be applied to the present invention.
5 is a diagram illustrating an image sensor in which an AF sensor is inserted.
FIG. 6 is a view for explaining contrast-contrast autofocus that can be applied to the present invention.
7 is a flowchart illustrating an operation of a mobile terminal according to an exemplary embodiment of the present invention.
8 is a diagram for explaining a correspondence relationship between each pixel of the light-receiving unit and the preview image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The mobile terminal described in this specification includes a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, a slate PC A tablet PC, an ultrabook, a wearable device such as a smartwatch, a smart glass, and a head mounted display (HMD). have.

However, it will be appreciated by those skilled in the art that the configuration according to the embodiments described herein may be applied to fixed terminals such as a digital TV, a desktop computer, a digital signage, and the like, will be.

1A to 1C are block diagrams for explaining a mobile terminal according to the present invention, and FIGS. 1B and 1C are conceptual diagrams showing an example of a mobile terminal according to the present invention in different directions.

The mobile terminal 100 includes a wireless communication unit 110, an input unit 120, a sensing unit 140, an output unit 150, an interface unit 160, a memory 170, a control unit 180, ), And the like. The components shown in FIG. 1A are not essential for implementing a mobile terminal, so that the mobile terminal described herein may have more or fewer components than the components listed above.

The wireless communication unit 110 may be connected between the mobile terminal 100 and the wireless communication system or between the mobile terminal 100 and another mobile terminal 100 or between the mobile terminal 100 and the external server 100. [ Lt; RTI ID = 0.0 > wireless < / RTI > In addition, the wireless communication unit 110 may include one or more modules for connecting the mobile terminal 100 to one or more networks.

The wireless communication unit 110 may include at least one of a broadcast receiving module 111, a mobile communication module 112, a wireless Internet module 113, a short distance communication module 114, and a location information module 115 .

The input unit 120 includes a camera 121 or an image input unit for inputting a video signal, a microphone 122 for inputting an audio signal, an audio input unit, a user input unit 123 for receiving information from a user A touch key, a mechanical key, and the like). The voice data or image data collected by the input unit 120 may be analyzed and processed by a user's control command.

The sensing unit 140 may include at least one sensor for sensing at least one of information in the mobile terminal, surrounding environment information surrounding the mobile terminal, and user information. For example, the sensing unit 140 may include a proximity sensor 141, an illumination sensor 142, a touch sensor, an acceleration sensor, a magnetic sensor, A G-sensor, a gyroscope sensor, a motion sensor, an RGB sensor, an infrared sensor, a finger scan sensor, an ultrasonic sensor, A microphone 226, a battery gauge, an environmental sensor (for example, a barometer, a hygrometer, a thermometer, a radiation detection sensor, A thermal sensor, a gas sensor, etc.), a chemical sensor (e.g., an electronic nose, a healthcare sensor, a biometric sensor, etc.). Meanwhile, the mobile terminal disclosed in the present specification can combine and utilize information sensed by at least two of the sensors.

The output unit 150 includes at least one of a display unit 151, an acoustic output unit 152, a haptic tip module 153, and a light output unit 154 to generate an output related to visual, auditory, can do. The display unit 151 may have a mutual layer structure with the touch sensor or may be integrally formed to realize a touch screen. The touch screen may function as a user input unit 123 that provides an input interface between the mobile terminal 100 and a user and may provide an output interface between the mobile terminal 100 and a user.

The interface unit 160 serves as a path to various types of external devices connected to the mobile terminal 100. The interface unit 160 is connected to a device having a wired / wireless headset port, an external charger port, a wired / wireless data port, a memory card port, And may include at least one of a port, an audio I / O port, a video I / O port, and an earphone port. In the mobile terminal 100, corresponding to the connection of the external device to the interface unit 160, it is possible to perform appropriate control related to the connected external device.

In addition, the memory 170 stores data supporting various functions of the mobile terminal 100. The memory 170 may store a plurality of application programs or applications running on the mobile terminal 100, data for operation of the mobile terminal 100, and commands. At least some of these applications may be downloaded from an external server via wireless communication. Also, at least a part of these application programs may exist on the mobile terminal 100 from the time of shipment for the basic functions (e.g., telephone call receiving function, message receiving function, and calling function) of the mobile terminal 100. Meanwhile, the application program may be stored in the memory 170, installed on the mobile terminal 100, and may be operated by the control unit 180 to perform the operation (or function) of the mobile terminal.

In addition to the operations related to the application program, the control unit 180 typically controls the overall operation of the mobile terminal 100. The control unit 180 may process or process signals, data, information, and the like input or output through the above-mentioned components, or may drive an application program stored in the memory 170 to provide or process appropriate information or functions to the user.

In addition, the controller 180 may control at least some of the components illustrated in FIG. 1A in order to drive an application program stored in the memory 170. FIG. In addition, the controller 180 may operate at least two of the components included in the mobile terminal 100 in combination with each other for driving the application program.

The power supply unit 190 receives external power and internal power under the control of the controller 180 and supplies power to the components included in the mobile terminal 100. The power supply unit 190 includes a battery, which may be an internal battery or a replaceable battery.

At least some of the components may operate in cooperation with one another to implement a method of operation, control, or control of a mobile terminal according to various embodiments described below. In addition, the operation, control, or control method of the mobile terminal may be implemented on the mobile terminal by driving at least one application program stored in the memory 170. [

Referring to FIGS. 1B and 1C, the disclosed mobile terminal 100 includes a bar-shaped terminal body. However, the present invention is not limited thereto and can be applied to various structures such as a folder type, a flip type, a slide type, a swing type, and a swivel type in which a watch type, a clip type, a glass type or two or more bodies are relatively movably coupled . A description of a particular type of mobile terminal, although relevant to a particular type of mobile terminal, is generally applicable to other types of mobile terminals.

Here, the terminal body can be understood as a concept of referring to the mobile terminal 100 as at least one aggregate.

The mobile terminal 100 includes a case (for example, a frame, a housing, a cover, and the like) that forms an appearance. As shown, the mobile terminal 100 may include a front case 101 and a rear case 102. Various electronic components are disposed in the inner space formed by the combination of the front case 101 and the rear case 102. At least one middle case may be additionally disposed between the front case 101 and the rear case 102.

A display unit 151 is disposed on a front surface of the terminal body to output information. The window 151a of the display unit 151 may be mounted on the front case 101 to form a front surface of the terminal body together with the front case 101. [

In some cases, electronic components may also be mounted on the rear case 102. Electronic parts that can be mounted on the rear case 102 include detachable batteries, an identification module, a memory card, and the like. In this case, a rear cover 103 for covering the mounted electronic components can be detachably coupled to the rear case 102. Therefore, when the rear cover 103 is separated from the rear case 102, the electronic parts mounted on the rear case 102 are exposed to the outside.

As shown, when the rear cover 103 is coupled to the rear case 102, a side portion of the rear case 102 can be exposed. In some cases, the rear case 102 may be completely covered by the rear cover 103 during the engagement. Meanwhile, the rear cover 103 may be provided with an opening for exposing the camera 121b and the sound output unit 152b to the outside.

These cases 101, 102, and 103 may be formed by injection molding of synthetic resin or may be formed of metal such as stainless steel (STS), aluminum (Al), titanium (Ti), or the like.

The mobile terminal 100 may be configured such that one case provides the internal space, unlike the above example in which a plurality of cases provide an internal space for accommodating various electronic components. In this case, a unibody mobile terminal 100 in which synthetic resin or metal is connected from the side to the rear side can be realized.

Meanwhile, the mobile terminal 100 may include a waterproof unit (not shown) for preventing water from penetrating into the terminal body. For example, the waterproof portion is provided between the window 151a and the front case 101, between the front case 101 and the rear case 102, or between the rear case 102 and the rear cover 103, And a waterproof member for sealing the inside space of the oven.

The mobile terminal 100 is provided with a display unit 151, first and second sound output units 152a and 152b, a proximity sensor 141, an illuminance sensor 142, a light output unit 154, Cameras 121a and 121b, first and second operation units 123a and 123b, a microphone 122, an interface unit 160, and the like.

1B and 1C, a display unit 151, a first sound output unit 152a, a proximity sensor 141, an illuminance sensor 142, an optical output unit (not shown) A second operation unit 123b, a microphone 122 and an interface unit 160 are disposed on a side surface of the terminal body, And a mobile terminal 100 having a second sound output unit 152b and a second camera 121b disposed on a rear surface thereof.

However, these configurations are not limited to this arrangement. These configurations may be excluded or replaced as needed, or placed on different planes. For example, the first operation unit 123a may not be provided on the front surface of the terminal body, and the second sound output unit 152b may be provided on the side surface of the terminal body rather than the rear surface of the terminal body.

The display unit 151 displays (outputs) information processed by the mobile terminal 100. For example, the display unit 151 may display execution screen information of an application program driven by the mobile terminal 100 or UI (User Interface) and GUI (Graphic User Interface) information according to the execution screen information .

The display unit 151 may be a liquid crystal display (LCD), a thin film transistor-liquid crystal display (TFT LCD), an organic light-emitting diode (OLED), a flexible display display, a 3D display, and an e-ink display.

In addition, the display unit 151 may exist in two or more depending on the embodiment of the mobile terminal 100. In this case, the mobile terminal 100 may be provided with a plurality of display portions spaced apart from each other or disposed integrally with one another, or may be disposed on different surfaces, respectively.

The display unit 151 may include a touch sensor that senses a touch with respect to the display unit 151 so that a control command can be received by a touch method. When a touch is made to the display unit 151, the touch sensor senses the touch, and the control unit 180 generates a control command corresponding to the touch based on the touch. The content input by the touch method may be a letter or a number, an instruction in various modes, a menu item which can be designated, and the like.

The touch sensor may be a film having a touch pattern and disposed between the window 151a and a display (not shown) on the rear surface of the window 151a, or may be a metal wire . Alternatively, the touch sensor may be formed integrally with the display. For example, the touch sensor may be disposed on a substrate of the display or inside the display.

In this way, the display unit 151 can form a touch screen together with the touch sensor. In this case, the touch screen can function as a user input unit 123 (see FIG. 1A). In some cases, the touch screen may replace at least some functions of the first operation unit 123a.

The first sound output unit 152a may be implemented as a receiver for transmitting a call sound to a user's ear and the second sound output unit 152b may be implemented as a loud speaker for outputting various alarm sounds or multimedia playback sounds. ). ≪ / RTI >

The window 151a of the display unit 151 may be provided with an acoustic hole for emitting the sound generated from the first acoustic output unit 152a. However, the present invention is not limited to this, and the sound may be configured to be emitted along an assembly gap (for example, a gap between the window 151a and the front case 101) between the structures. In this case, the appearance of the mobile terminal 100 can be made more simple because the hole formed independently for the apparent acoustic output is hidden or hidden.

The optical output unit 154 is configured to output light for notifying the occurrence of an event. Examples of the event include a message reception, a call signal reception, a missed call, an alarm, a schedule notification, an email reception, and reception of information through an application. The control unit 180 may control the light output unit 154 to terminate the light output when the event confirmation of the user is detected.

The first camera 121a processes an image frame of a still image or a moving image obtained by the image sensor in the photographing mode or the video communication mode. The processed image frame can be displayed on the display unit 151 and can be stored in the memory 170. [

The first and second operation units 123a and 123b may be collectively referred to as a manipulating portion as an example of a user input unit 123 operated to receive a command for controlling the operation of the mobile terminal 100 have. The first and second operation units 123a and 123b can be employed in any manner as long as the user is in a tactile manner such as touch, push, scroll, or the like. In addition, the first and second operation units 123a and 123b may be employed in a manner that the user operates the apparatus without touching the user through a proximity touch, a hovering touch, or the like.

In this figure, the first operation unit 123a is a touch key, but the present invention is not limited thereto. For example, the first operation unit 123a may be a mechanical key or a combination of a touch key and a touch key.

The contents input by the first and second operation units 123a and 123b can be variously set. For example, the first operation unit 123a receives a command such as a menu, a home key, a cancellation, a search, and the like, and the second operation unit 123b receives a command from the first or second sound output unit 152a or 152b The size of the sound, and the change of the display unit 151 to the touch recognition mode.

On the other hand, a rear input unit (not shown) may be provided on the rear surface of the terminal body as another example of the user input unit 123. The rear input unit is operated to receive a command for controlling the operation of the mobile terminal 100, and input contents may be variously set. For example, commands such as power on / off, start, end, scrolling, and the like, the size adjustment of the sound output from the first and second sound output units 152a and 152b, And the like can be inputted. The rear input unit may be implemented as a touch input, a push input, or a combination thereof.

The rear input unit may be disposed so as to overlap with the front display unit 151 in the thickness direction of the terminal body. For example, the rear input unit may be disposed at the rear upper end of the terminal body such that when the user holds the terminal body with one hand, the rear input unit can be easily operated using the index finger. However, the present invention is not limited thereto, and the position of the rear input unit may be changed.

When a rear input unit is provided on the rear surface of the terminal body, a new type of user interface using the rear input unit can be realized. When the first operation unit 123a is not disposed on the front surface of the terminal body in place of at least a part of the functions of the first operation unit 123a provided on the front surface of the terminal body, The display unit 151 may be configured as a larger screen.

Meanwhile, the mobile terminal 100 may be provided with a fingerprint recognition sensor for recognizing the fingerprint of the user, and the controller 180 may use the fingerprint information sensed through the fingerprint recognition sensor as authentication means. The fingerprint recognition sensor may be embedded in the display unit 151 or the user input unit 123.

The microphone 122 is configured to receive the user's voice, other sounds, and the like. The microphone 122 may be provided at a plurality of locations to receive stereophonic sound.

The interface unit 160 is a path through which the mobile terminal 100 can be connected to an external device. For example, the interface unit 160 may include a connection terminal for connection with another device (for example, an earphone or an external speaker), a port for short-range communication (for example, an infrared port (IrDA Port), a Bluetooth port A wireless LAN port, or the like), or a power supply terminal for supplying power to the mobile terminal 100. The interface unit 160 may be implemented as a socket for receiving an external card such as a SIM (Subscriber Identification Module) or a UIM (User Identity Module) or a memory card for storing information.

And a second camera 121b may be disposed on a rear surface of the terminal body. In this case, the second camera 121b has a photographing direction which is substantially opposite to that of the first camera 121a.

The second camera 121b may include a plurality of lenses arranged along at least one line. The plurality of lenses may be arranged in a matrix form. Such a camera may be termed an "array camera ". When the second camera 121b is configured as an array camera, images can be taken in various ways using a plurality of lenses, and a better quality image can be obtained.

The flash 124 may be disposed adjacent to the second camera 121b. The flash 124 shines light toward the subject when the subject is photographed by the second camera 121b.

And a second sound output unit 152b may be additionally disposed in the terminal body. The second sound output unit 152b may implement a stereo function together with the first sound output unit 152a and may be used for implementing a speakerphone mode in a call.

The terminal body may be provided with at least one antenna for wireless communication. The antenna may be embedded in the terminal body or formed in the case. For example, an antenna constituting a part of the broadcast receiving module 111 (see FIG. 1A) may be configured to be able to be drawn out from the terminal body. Alternatively, the antenna may be formed in a film type and attached to the inner surface of the rear cover 103, or a case including a conductive material may be configured to function as an antenna.

The terminal body is provided with a power supply unit 190 (see FIG. 1A) for supplying power to the mobile terminal 100. The power supply unit 190 may include a battery 191 built in the terminal body or detachable from the outside of the terminal body.

The battery 191 may be configured to receive power through a power cable connected to the interface unit 160. In addition, the battery 191 may be configured to be wirelessly chargeable through a wireless charger. The wireless charging may be implemented by a magnetic induction method or a resonance method (magnetic resonance method).

The rear cover 103 is configured to be coupled to the rear case 102 so as to cover the battery 191 to restrict the release of the battery 191 and to protect the battery 191 from external impact and foreign matter . When the battery 191 is detachably attached to the terminal body, the rear cover 103 may be detachably coupled to the rear case 102.

The mobile terminal 100 may be provided with an accessory that protects the appearance or supports or expands the function of the mobile terminal 100. [ One example of such an accessory is a cover or pouch that covers or accommodates at least one side of the mobile terminal 100. [ The cover or pouch may be configured to interlock with the display unit 151 to expand the function of the mobile terminal 100. Another example of an accessory is a touch pen for supplementing or extending a touch input to the touch screen.

The mobile terminal 100 according to the present invention may include at least one of the components shown in Figs. 1A to 1C. In detail, the mobile terminal according to the present invention may include a camera 121, a display unit 151, a memory 160, and a controller 180. In the following drawings, for example, a mobile phone will be described as an example of the mobile terminal 100, but an electronic device (e.g., a digital camera, a mirrorless camera, a tablet PC, a PDA, etc.) May be applied.

The camera 121 provided in the mobile terminal 100 may include a lens and an imaging device. The lens is for collecting or dispersing the light, and the image sensor forms the light passing through the lens and converts the formed image into an electric signal. The distance between the lens and the image sensor may be referred to as the " focal length ".

The control unit 180 can perform autofocus to adjust the distance between the lens and the image sensor in order to focus on the subject at the time of photographing.

At this time, the mobile terminal 100 according to the present invention may adjust the focal distance based on the distance measurement method, and may further correct at least one of the contrast method and the phase difference method to correct the focal distance. First, the autofocus by the distance measuring method, the contrast method, and the phase difference method will be described in detail.

2 is a view for explaining autofocus of a distance measuring method applicable to the present invention. The mobile terminal 100 according to the present invention may include a light emitting portion 210 and a light receiving portion 220 in order to utilize the distance measurement type autofocus.

The light emitting portion 210 serves to generate light. Specifically, light such as a laser or infrared ray having a strong directivity can be outputted through the light emitting portion 210.

The light receiving unit 220 serves to receive light reflected by the object.

When light such as a laser or infrared rays is emitted through the light emitting unit 210, light such as a laser or infrared rays is reflected by being hitting a subject. Light reflected by the subject can be received through the light receiving unit 220. [ At this time, the control unit 180 calculates the distance between the camera 121 and the subject based on the time taken until the light-receiving unit 220 detects the reflected light after the light is emitted through the light-emitting unit 210 Can be calculated. When the distance between the camera 121 and the subject is calculated, the control unit 180 can adjust the focal distance according to the distance between the camera 121 and the subject.

As another example, the control unit 180 may adjust the focal distance based on the time taken for the light receiving unit to detect the reflected light after the light is emitted through the light emitting unit.

2 shows a lookup table in which the focus position is determined according to the distance between the camera 121 and the subject and a lookup table in which the focus position is determined according to the time taken for the reflected light to be detected after the light is emitted. Was shown.

In FIG. 2, autofocus is performed on the basis of the time taken for the reflected light to be detected after the light is emitted.

Unlike the example shown in the drawing, a distance measurement type autofocus may be performed using ultrasonic waves instead of light.

FIG. 3 is a view showing another example for explaining autofocus of a distance measurement method applicable to the present invention. The mobile terminal 100 may include an ultrasound generating unit 310 and a sound collecting unit 320 in order to utilize the autofocus of the distance measurement system using the ultrasonic waves.

The ultrasonic wave generator 310 generates ultrasonic waves.

The sound collector (# 20) plays a role of receiving an echo sound.

When the ultrasonic wave is generated through the ultrasonic wave generator 310, the ultrasonic wave is hit by the object, and thus an echo of the ultrasonic wave may occur. Accordingly, the sound collecting unit 320 can receive a sound that is generated when the object is hitting the object. The control unit 180 calculates the distance between the camera 121 and the subject based on the time taken for the sound collector 320 to detect a sound after the ultrasonic wave is generated through the ultrasonic generator 310 can do. When the distance between the camera 121 and the subject is calculated, the control unit 180 can adjust the focal distance according to the distance between the camera 121 and the subject.

Alternatively, the control unit 180 may adjust the focal distance based on the time taken for the sound collector 320 to detect the sound of ringing after the ultrasonic wave is emitted through the ultrasonic generator 310.

In FIG. 3, after a lookup table and an ultrasonic wave, which determine the focus position (that is, the focal distance when the subject is focused), are emitted according to the distance between the camera 121 and the subject, A look-up table is shown in which the focus position is determined according to the time that has elapsed.

The autofocus of the distance measuring method as shown in Figs. 2 and 3 has an advantage that autofocus can be performed quickly. In addition, there is an advantage in that autofocus can be performed without difficulty even in low light.

However, when the subject is far away from the camera 121, there is a disadvantage that accuracy is degraded. In addition, when light such as a laser or an infrared ray is used, there is a disadvantage in that the accuracy is lowered in an environment in which sunlight is exposed.

4 is a view for explaining a phase difference autofocus that can be applied to the present invention. As in the example shown in FIG. 4 (a), before the light passing through the lens passes through the image sensor, a part of the light may be reflected on the mirror and sent to two AF sensors.

Then, the control unit 180 can measure the phase difference between the two AF sensors to determine whether to increase or decrease the focal distance. Specifically, as in the example shown in Fig. 4 (b), the control unit 180 can be regarded as focused on the subject if there is no phase difference between the two AF sensors. Alternatively, when the phase of the first AF sensor is higher than the phase of the second AF sensor, the control unit 180 reduces the focal distance, and if the phase of the first AF sensor is lower than the phase of the second AF sensor, The focus position can be determined.

When inserting an AF sensor in the image sensor, it is possible to perform a mirrorless phase difference autofocus. For example, FIG. 5 illustrates an image sensor in which an AF sensor is inserted. As in the example shown in Fig. 5, when the image sensor and the AF sensor are simultaneously embedded in the image sensor, the phase difference type autofocus can be performed through the AF sensor embedded in the image sensor.

The phase difference type autofocus has an advantage that autofocus can be relatively accurately performed. However, there is a disadvantage in that the autofocus accuracy is lowered in a low-light environment in which the amount of light is small.

The phase difference type autofocus system does not need to move the lens over the entire focal distance unlike the contrast difference type autofocus system which will be described later. For example, when the focal length is in the range of 10 to 50 mm, when the focal length of the lens is increased from 10 mm to 20 mm, the phase of the first AF sensor is higher than the phase of the second AF sensor, If the phase of the first AF sensor is lower than the phase of the second AF sensor, it is not necessary to move the lens for a portion exceeding 25 mm. That is, the controller 180 can perform autofocusing by moving the lens only within a range of 10 mm to 25 mm in the range of 10 to 50 mm in total.

However, if the initial position of the lens is far away from the focus position, autofocus of the phase difference system may take a long time.

FIG. 6 is a view for explaining contrast-contrast autofocus that can be applied to the present invention. The control unit 180 may perform image analysis while adjusting the focal distance of the camera 121. [ For example, if the focal length has a range of 10 to 50 mm, the controller 180 can perform image analysis while adjusting the focal distance between the lens and the image sensor to 10 to 50 mm.

Thereafter, the controller 180 can determine the focal length as the focal position when the contrast difference is greatest at the edge and the edge, as a result of the image analysis. Here, the edge may mean a boundary of an image or character or an object. For example, if an image sensing a person in the landscape is input, the boundary between the person and the background may be set as an edge.

The contrast-based autofocus has the advantage that autofocus can be performed accurately. However, since the image analysis is performed over the entire range of the focal length, there is a disadvantage that the speed is slow and the accuracy is low at low illumination. In addition, there is a disadvantage in that the accuracy of the subject near the camera 121 is low.

Table 1 summarizes the advantages and disadvantages of each of the above-described autofocus systems.

division Distance-based method Phase difference method Contrast method accuracy lowness height height speed speed usually Slow Accuracy at low light levels height lowness lowness Accuracy at high level lowness height height

In the present invention, a method of performing autofocus with high accuracy and high speed by applying the above-described distance difference autofocus, phase difference autofocus and contrast difference autofocus will be disclosed. The mobile terminal 100 according to the present invention will be described in detail with reference to the following drawings.

7 is a flowchart illustrating an operation of the mobile terminal 100 according to an embodiment of the present invention.

When the camera 121 is activated, a preview image is output, and a predetermined position in the preview image is touched (S701), the controller 180 can measure the distance to the subject (S702). Specifically, the control unit 180 can measure the distance between the camera 121 and the object through a laser or an ultrasonic wave.

At this time, the light receiving unit may be composed of a pixel array. The control unit 180 can measure the time required until the light reflected by each pixel is received after the light is emitted. Thus, the distance between the subject and each pixel can be measured. At this time, each pixel of the light receiving unit may correspond to each region of the preview image. The preview image may be an image input through the camera 121 before the photograph or the moving image is captured through the camera 121. [

8 is a diagram for explaining a correspondence relationship between each pixel of the light-receiving unit and the preview image.

For convenience of explanation, it is assumed that the pixel array is composed of 16 pixels, and that the preview image is divided into 16 regions by the number of pixel arrays.

The N-th pixel of the pixel array may correspond to the N-th area of the display unit 151. For example, the pixel # 1 may correspond to the area # 1 of the preview image. Accordingly, the time taken until the N-th pixel receives the light can be used to measure the distance to the object located in the area N of the preview image. Thus, the control unit 180 can measure the distance to the subject in each area for each area of the preview image.

When the distance measurement with respect to the subject is completed, the control unit 180 can set the focus position based on the distance to the subject in the area corresponding to the touch position of the user (S703). For example, in the example shown in FIG. 8, if the user touches the fifth area of the preview area, the controller 180 determines whether the fifth pixel is in focus The position can be determined.

Thereafter, the control unit 180 can perform the focus position correction through the phase difference autofocus (S704). Specifically, the control unit 180 can position the lens at the focal position and adjust the focal position based on the phase difference between the two AF sensors (or the image sensor with the AF sensor embedded therein) have. Due to the distance difference type autofocusing, the initial position of the lens becomes close to the absolute focal position, so that the moving distance of the lens through the phase-difference autofocus can be shortened.

When the focus position correction through the phase difference autofocus is completed, the controller 180 can perform the secondary focus position correction through the contrast auto focus (S705). Specifically, the control unit 180 can perform the secondary correction by positioning the lens at the corrected focal position through the phase-difference autofocus, and performing image analysis within a predetermined focal length before and after the corrected focal position . For example, if the focal length of 25 mm is determined to be the corrected focal position by the phase difference autofocus in the range of 10 to 50 mm, the control unit 180 controls the lens in the range of 2 mm before the 25 mm focal length and 2 mm after (i.e., 23 to 27 mm) So that image analysis can be performed. The controller 180 can determine the position at which the contrast difference is greatest at the edge portion within the range of the focal length of 23 to 27 mm as the secondary corrected focal position. As described above, by limiting the focal distance for performing image analysis to a part of the entire focal length, the execution speed of the contrast auto focus can be increased.

As the lens moves to the secondary corrected focal position, the autofocusing can be terminated.

7, when the distance between the camera 121 and the subject is not measured (S702), the controller 180 can directly determine the focus position through the phase-difference autofocus (S704). In this case, the moving distance of the lens is longer than that of performing the focus position correction through the phase difference autofocus after determining the focus position through the distance difference autofocus, so that the time required for performing the phase difference autofocus may increase. When the focus position is determined through the phase difference autofocus, as described above with reference to FIG. 7, the focus position correction through contrast autofocus can be performed.

After the autofocus is completed, if the user touches an arbitrary point of the preview image, the controller 180 may again perform the distance difference autofocus. At this time, the control unit 180 may measure the distance to the subject by newly emitting light through the light emitting unit, or may measure the distance to the subject based on the reception record of the light receiving unit with respect to the light emitted immediately before the light emitting unit .

8, if the user inputs a touch of the seventh area of the preview image in a state where the fifth area of the preview image is focused, the controller 180 newly emits light through the light emitting unit The distance from the subject can be measured on the basis of the time taken until the pixel 7 of the light receiving section receives light.

Alternatively, instead of emitting light through the light emitting unit, the control unit 180 may control the light emitted by the previous light emitting unit (i.e., the light emitted from the light emitting unit when the fifth area is touched before the seventh area is touched) It is also possible to measure the distance from the subject based on the time taken to receive the reflected light of the pixel No. 7 of the light receiving unit.

The control unit 180 controls the light emitting unit to emit light when a user input for touching an arbitrary position of the preview image is received after a predetermined time has elapsed since the light was emitted, When a user input touching the position is received, the distance to the subject can be controlled using the received record of the light receiving unit with respect to the light emitted from the immediately preceding light emitting unit.

According to one embodiment of the present invention, the above-described method (operation flow diagram) can be implemented as a code that can be read by a processor on a medium on which the program is recorded. Examples of the medium that can be read by the processor include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, etc., and may be implemented in the form of a carrier wave (e.g., transmission over the Internet) .

The above-described mobile terminal 100 is not limited in the configuration and method of the above-described embodiments, but the embodiments may be modified such that all or some of the embodiments are selectively combined .

100: mobile terminal
121: camera
151:
160: Memory
180:

Claims (5)

A camera including a lens and an image sensor;
A light emitting portion for emitting light;
A light receiving unit for receiving reflected light when the light emitted through the light emitting unit is reflected;
At least two AF (Auto Focus) sensors for receiving at least a portion of the light passing through the lens;
A display unit for displaying a preview image input through the camera before photographing; And
And a controller for determining a focus position focused on a subject indicated by the touched position based on the time taken for the light receiving unit to receive the reflected light when the touched position on the preview image is touched, Based on the phase difference between the focus position and the focus position,
. The method according to claim 1,
Wherein the control unit changes the focal distance between the lens and the imager and performs a secondary correction on the focal position on the basis of a contrast difference based on an input image edge. terminal. 3. The method of claim 2,
Wherein the controller calculates the contrast difference with respect to an image obtained within a predetermined distance before and after the first corrected focal position. The method according to claim 1,
Wherein the light receiving unit is composed of a plurality of pixels,
The control unit controls the plurality of pixels so that each of the plurality of pixels receives the reflected light. Of the mobile terminal is measured. Displaying a preview image input through a camera before photographing;
Emitting light through a light emitting portion;
Receiving the reflected light when the light emitted through the light emitting unit is reflected;
Determining a focus position focused on a subject indicated by the touched position based on a time taken for the light receiving unit to receive the reflected light when a position on the preview image is touched; And
Performing a first-order correction on the focal position based on a phase difference between the AF sensors
And transmitting the control information to the mobile terminal.

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