KR20160036312A - Lens assembly - Google Patents

Abstract

The present invention relates to a lens assembly installed to a camera module arranged on a front surface of a terminal body. The lens assembly comprises: an aperture which controls sequentially an amount of light from an object part; a first lens which has positive refractive power; a second lens having a negative refractive power; a third lens having positive refractive power; and a fourth lens having negative refractive power. As such, a slim camera module is able to be achieved.

Description

[0001] LENS ASSEMBLY [0002]

The present invention relates to a lens assembly, and more particularly, to a lens assembly mounted on a camera module disposed on a front surface of a terminal body.

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, a multimedia player having a complex function such as photographing or moving picture shooting, reproduction of music or video file, reception of game or broadcasting, . In order to support and enhance the functionality of such terminals, it may be considered to improve the structural and / or software parts of the terminal.

On the other hand, according to the recent slimming and wide angle of the mobile terminal, a thin thickness is required for the camera module mounted on the terminal. Accordingly, in order to make a slim wide-angle camera, it is necessary that the size of the image sensor is the same as or smaller than that of the conventional image sensor. In order to realize a wide-angle camera, I can not help it. Therefore, in order to sufficiently gather light at a larger lens aperture, the resolving power of the lens must be increased. In order for the lens to have sufficient resolution, a large number of lenses must be used.

However, when a large number of lenses are used, the overall thickness of the lens assembly becomes thicker, which has led to a tendency to become slim recently, and since light is transmitted through many lenses, the brightness of the whole image is lowered due to reduction of light transmittance, A problem arises. Accordingly, there is a demand for a lens assembly of a new structure capable of realizing a high-quality wide-angle image in accordance with the slimming trend of a mobile terminal.

The present invention is directed to solving the above-mentioned problems and other problems. Another object of the present invention is to provide a lens assembly capable of realizing a high-quality wide-angle image while reducing the size of the camera module.

According to an aspect of the present invention, there is provided an illumination device including: a diaphragm for adjusting an amount of light in order from an object side; A first lens having positive refractive power; A second lens having a negative refractive power; A third lens having positive refractive power; And a fourth lens having a negative refractive power.

According to another aspect of the present invention, there is provided a zoom lens comprising a diaphragm for adjusting an amount of light in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, A third lens having a refractive power of negative (-) power and a fourth lens having negative (-) refractive power; And an image sensor for converting an optical signal incident from the lens assembly into an electrical signal.

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, by mounting a lens assembly, in which four lenses having refractive power of the positive (+ - + -) from the object side are arranged in order, to the front camera module, And a high-quality wide-angle image can be realized at the same time.

Meanwhile, various other effects will be directly or implicitly disclosed in the detailed description according to the embodiment of the present invention to be described later.

FIG. 1A is a block diagram illustrating a mobile terminal according to the present invention; FIG.
FIG. 1B and FIG. 1C are conceptual diagrams showing an example of a mobile terminal according to the present invention in different directions; FIG.
2 is a diagram for describing a camera module of a mobile terminal according to the present invention;
3 is a view referred to explain the configuration of the lens assembly according to the first embodiment of the present invention;
4 is a graph illustrating aberration characteristics of a lens assembly according to a first embodiment of the present invention;
5 is a diagram for describing a configuration of a lens assembly according to a second embodiment of the present invention;
6 is a graph illustrating aberration characteristics of a lens assembly according to a second embodiment of the present invention;
FIG. 7 is a view referred to explain a configuration of a lens assembly according to a third embodiment of the present invention; FIG.
8 is a graph showing aberration characteristics of a lens assembly according to a third embodiment of the present invention;
9 is a view referred to illustrate a change in the angle of incidence (CRA) with a change in distance between a lens assembly and an image sensor;

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.

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 simplified because the holes that are formed independently for the apparent acoustic output are 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. [

In addition, the first camera 121a 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 can be named an 'array camera'. When the first camera 121a 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 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 manipulated 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 can be named 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.

In the foregoing, the configuration of the mobile terminal 100 according to the present invention has been described with reference to FIGS. 1A to 1C. Hereinafter, a camera module used in a mobile terminal according to the present invention and a lens assembly mounted on the camera module will be described in detail.

2 is a diagram for explaining a camera module of a mobile terminal according to the present invention.

2, a camera module 121 according to an exemplary embodiment of the present invention includes a lens assembly 300, a lens barrel 210, an actuator 220, and an image sensor 230. Although not shown in the drawing, the present camera module 121 includes a printed circuit board (not shown) for processing a signal of the image sensor 230, and a lens barrel 210 coupled to the lens barrel 210, And a bobbin (not shown).

The lens assembly 300 is configured by arranging a plurality of lenses in a line along the optical axis and refracting light so that a large amount of light can be drawn from one point of the subject and gathered at one point. At this time, the light rays that run straight from one point are gathered to one place through the lens, and the lights gather to form one image. At this time, the distance between the image sensor 230 and the lens, ).

The lens barrel 210 serves as a housing for protecting the lens assembly 300 and moves in the direction of the optical axis according to the driving of the actuator 220. [ The actuator 220 performs an auto focus (AF) function by moving the lens barrel 210 and the bobbin along the optical axis direction through an electromagnetic force using a coil. At this time, the actuator 220 may be composed of a voice coil motor (VCM) or the like.

The image sensor 230 is spaced apart from the lens assembly 300 and functions to convert an optical signal input through the lens assembly 300 into an electrical signal. At this time, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) may be used as the image sensor 230.

First Embodiment

3 is a view for explaining the configuration of the lens assembly according to the first embodiment of the present invention. In the configuration of FIG. 3, the thickness, size, and shape of the lens are shown somewhat exaggerated for explanatory purposes, and the spherical or aspherical shape is not limited to this shape, but is only shown as one embodiment.

Referring to FIG. 3, the lens assembly 300 according to the first embodiment of the present invention includes an aperture stop S _top 305, a first lens 310, a second lens 320, A lens 330, a fourth lens 340, an infrared ray filter 350, and an image sensor 230 are disposed.

The light corresponding to the image information of the object passes through the diaphragm 305, the first lens 310, the second lens 320, the third lens 330, the fourth lens 340, and the infrared filter 350 And is incident on the image sensor 230.

The aperture (S _top , 305 are located at the front portion of the lens assembly 300 (i.e., the front portion of the first lens) to adjust the amount of light incident on the optical system. On the other hand, in another embodiment, the diaphragm 305 may be disposed between the lens and the lens.

The first through fourth lenses 310, 320, 330, and 340 may be formed of a plastic material having a predetermined refractive index. Therefore, if all the lenses constituting the lens assembly 300 are made of plastic material, not only the manufacturing cost of the lens assembly 300 can be reduced but also mass production is possible.

Also, the first to fourth lenses 310, 320, 330, and 340 can use an aspheric lens on at least one side or both sides to improve the resolving power of the lens and to take advantage of aberration characteristics.

Hereinafter, the term " Object Side "refers to the surface of the lens that faces the object side with respect to the optical axis Z _o , and" Image Side " Refers to the surface of the lens that faces the imaging surface with respect to the optical axis Z _o .

The first lens 310 has a positive refractive power (or refractive power), and the object side surface S1 is convex. A diaphragm 305 is disposed on the object side surface S1 of the first lens 310. [

The second lens 320 has a negative refractive power, and the object side surface S3 is concave. The lens assembly 300 and the image sensor 230 may be formed by increasing the size of the chief ray angle (CRA) incident on the image sensing plane by disposing the lens having the negative refracting power at the second position from the object side, So that a sufficient size image can be obtained even though the distance between the two images is short. At this time, in order to further increase the size of the incident angle (CRA) through the second lens 320, a high refractive index plastic material having a refractive index of 1.6 or more may be used for the second lens 320.

The third lens 330 has a positive refractive power, and the upper side S6 is convex. The fourth lens 340 has a negative refractive power. As shown in the figure, the fourth lens 340 may have an aspherical shape in which the object side surface S7 and the upper surface side S8 both have inflection points.

As described above, the lens assembly 300 having the structure of the PNPN (+ - + -) has the overall slim structure due to the lenses having the negative refracting power.

Also, the lens assembly 300 increases the size of the incident angle CRA incident on the imaging surface using the second lens 320 and the fourth lens 340 having negative refractive power. Accordingly, it is possible to realize a high-quality wide-angle image even if the distance between the lens assembly 300 and the image sensor 230 is short.

For example, as shown in FIG. 9, in order to make a slim wide-angle lens structure with the same size and number of pixels of the image sensor, the incident angle CRA incident on the imaging surface in the lens assembly must be large. In order to increase the size of the incident angle CRA, lenses having a negative refracting power are suitably adopted in the lens assembly 300, and the light incident from the object side is spread on the image sensor 230 to a sufficient size .

Referring to FIG. 3, more specifically, light gathered through the first lens 310 having a positive refractive power is spread to a sufficient size through the second lens 320 having a negative refractive power. Then, the light passing through the second lens 320 is collected again through the third lens 330 having a positive refractive power, thereby correcting the resolution of the image. Finally, by again spreading the resolution-corrected light through the fourth lens 340 having a negative refractive power, even though a short distance between the lens assembly 300 and the image sensor 230, So that the image can be acquired.

The infrared filter 350 is disposed between the fourth lens 340 and the image sensor 230 and functions to block radiant heat emitted from external light from being transmitted to the image sensor 230. In addition, the infrared filter 350 transmits visible light and reflects infrared light to the outside. Meanwhile, in another embodiment, the infrared filter 350 may be configured in the form of a coating film, and may be attached to the upper surface S8 of the fourth lens 340. [

The image sensor 230 converts an optical signal transmitted through the diaphragm 305, the first through fourth lenses 310, 320, 330, and 340 and the infrared filter 350 into an electrical signal.

It will be apparent to those skilled in the art that the conditional expressions described below are preferred embodiments for increasing the operative effect of the lens assembly and that the present invention is not necessarily constructed with the following conditions. For example, the lens configuration of the present invention may have an elevated action effect even if only the conditional formulas of some of the conditional expressions described below are satisfied.

[Conditional expression 1]

0.5 < K ₁ / K _t < 1.0

[Conditional expression 2]

0.3 < K ₂ / K _t | < 1

[Conditional expression 3]

1.0 < K ₃ / K _t | <1.5

[Conditional expression 4]

0.5 < K ₄ / K _t | <1.3

Here, K: 1 / focal length (f) of the lens,

K ₁ , K ₂ , K ₃ , K ₄ : The refractive power of the first to fourth lenses,

K _t : The refractive power of the entire lens.

The above conditional expressions 1 to 4 define the refractive powers of the first to fourth lenses 310, 320, 330, and 340 of the lens assembly according to the embodiments of the present invention.

Table 1 below shows first to fourth lenses constituting the lens assembly according to the first embodiment of the present invention. At this time, the first to fourth lenses are designed to satisfy the above-mentioned conditional expressions.

lens Face number The radius of curvature (R) thickness Refractive index (N) Abe number Focal length
(f) Conditional expression
(| K _n / K _t |) 1st
lens
One* 1.35977 0.47 1.528208 54 2.049698 0.796751 2* -4.678033 0.1 Second
lens
3 * -14.83932 0.25 1.63242 23.35 -3.32432 0.491258 4* 2.465373 0.14 Third
lens
5 * -4.20954 0.51 1.528208 54 1.38942 1.175382 6 * -0.651118 0.1 Fourth
lens
7 * 0.649592 0.25 1.528208 54 -2.21547 0.737134 8* 0.362153 0.42

The symbol "* " next to the surface number in Table 1 indicates an aspherical surface.

Referring to Table 1, it can be confirmed that the conditional expressions (| K _n / K _t |) for the first to fourth lenses are 0.796751, 0.491258, 1.175382, and 0.737134, respectively.

In addition, the F-number of the lens assembly 300 according to the first embodiment of the present invention shows a performance of 2.09, and the half-field of view (HFOV) shows a performance of 45 degrees. Here, the F-number is a numerical value representing the brightness of the lens, and is represented by F = f / D when the focal length of the optical system is f and the aperture is D. [ Normally, the lower the F-number is, the more the brightness of the lens increases. Therefore, it can be confirmed that a bright image can be obtained through the lens assembly 300 because the F-number of the lens assembly 300 according to the first embodiment has a value of 2.09.

The half angle of view (HFOV) represents a half of the viewing angle of a scene that can be captured by a camera lens. Therefore, it can be seen that the wide angle image can be ensured through the lens assembly 300 because the half angle of view (HFOV) of the lens assembly 300 according to the first embodiment is 45 degrees.

Meanwhile, the first through fourth lenses 310, 320, 330, and 340 of the lens assembly according to the present invention have the refractive power with proper spherical aberration correction and appropriate chromatic aberration according to the above-described conditional expressions 1 to 4. In addition, the aspherical surface referred to in the embodiments of the present invention can be obtained from the known equation (1).

Here, Z is the distance from the apex of the lens in the direction of the optical axis

c: The basic curvature of the lens

Y: Distance in the direction perpendicular to the optical axis

α: Conic constant

A, B, C, D, E, and F are the aspheric coefficients of the respective orders.

Table 2 below shows values of the aspherical surface coefficients of the respective lenses constituting the lens assembly according to the embodiment of Table 1.

division The first lens The second lens Third lens The fourth lens One* 2* 3 * 4* 5 * 6 * 7 * 8* alpha -1.671758 40.741171 0 -80.568919 -192.487642 -1.566363 0 0 A -0.071482 -1.104473 -1.762463 -0.205613 0.112248 0.063235 -0.633613 -0.573594 B 0.128487 0.050687 0.906158 -0.580590 -0.139419 0.158955 0.244525 0.681479 C -8.035430 -0.223167 1.523121 2.015954 -0.492175 -1.065838 0.006787 -0.525020 D 30.594848 -9.879813 -15.052213 2.830820 1.267742 1.397262 -0.023760 0.216743 E -67.515680 6.546767 21.353713 -24.355527 5.973815 4.153613 0.108664 -0.047832 F -15.189621 6.977689 34.478938 -0.574357 -20.7366126 -3.629568 -0.005425 0.003913 G -45.044519 58.920493 0 0 0 0 0 0.003024 H 0 0 0 0 0 0 0 -0.000931 I 0 0 0 0 0 0 0 -0.000093

FIG. 4 is a graph showing the aberration characteristics of the lens assembly according to the first embodiment of the present invention. FIG. 4 is a graph showing astigmatic field curves and distortion in order from the left.

In Fig. 4, the Y axis represents the size of the image, and the X axis represents the focal length (in mm) and distortion (in%). Generally, the closer the aberration curves are to the Y-axis, the better the aberration correction function is. Therefore, in the aberration diagram shown in FIG. 4, since the values of the images appear near the Y-axis in almost all the fields, it can be confirmed that both the astigmatism and the distortion aberration are excellent values.

Second Embodiment

5 is a view for explaining a configuration of a lens assembly according to a second embodiment of the present invention.

5, the lens assembly 500 according to the second embodiment of the present invention, the diaphragm (S _top in the order from the object side, 505, a first lens 510, a second lens 520, a third lens 530, a fourth lens 540, an infrared ray filter 550, and an image sensor 230 are disposed.

The aperture (S _top , 505 are located at the front portion of the lens assembly 500 (i.e., the front portion of the first lens) to adjust the amount of light incident on the optical system. On the other hand, in another embodiment, a diaphragm 505 may be disposed between the lens and the lens.

The first through fourth lenses 510, 520, 530, and 540 may be formed of a plastic material having a predetermined refractive index. In addition, the first through fourth lenses 510, 520, 530, and 540 may use aspheric lenses on at least one side or both sides.

The first lens 510 has a positive refractive power, and the object side surface S1 is convex. A diaphragm 505 is disposed on the object side surface S1 of the first lens 510. [

The second lens 520 has a negative refractive power, and the object side surface S3 is concave. The distance between the lens assembly 500 and the image sensor 230 is increased by increasing the size of the incident angle CRA incident on the image sensing plane by arranging the lens having the negative refracting power at the second position from the object side So that a sufficient size image can be obtained despite the shortness. At this time, in order to further increase the size of the incident angle (CRA) through the second lens 520, a high refractive index plastic material having a refractive index of 1.6 or more may be used for the second lens 520.

The third lens 530 has a positive refractive power, and the upper side S6 is convex. The fourth lens 540 has a negative refractive power. As shown in the figure, the fourth lens 540 may have an aspherical shape in which the object side surface S7 and the upper surface side S8 both have inflection points.

As described above, the lens assembly 500 having the structure of the PNPN (+ - + -) has the overall slim structure due to the lenses having the negative refracting power.

In addition, the lens assembly 500 increases the size of the incident angle CRA incident on the imaging surface by using the second lens 520 and the fourth lens 540 having negative refractive power. Accordingly, it is possible to realize a high-quality wide-angle image even if the distance between the lens assembly 500 and the image sensor 230 is short.

The infrared filter 550 is disposed between the fourth lens 540 and the image sensor 230 and functions to block radiant heat emitted from external light from being transmitted to the image sensor 230. In addition, the infrared filter 550 transmits visible light and reflects the infrared light to the outside. Meanwhile, in another embodiment, the infrared filter 550 is configured in the form of a coating film and may be attached to the upper surface S8 of the fourth lens 540. [

The image sensor 230 converts an optical signal incident through the diaphragm 505, the first through fourth lenses 510, 520, 530, and 540 and the infrared filter 550 into an electrical signal.

Table 3 below shows first to fourth lenses constituting the lens assembly according to the second embodiment of the present invention. At this time, the first to fourth lenses are designed to satisfy the above-mentioned conditional expressions.

lens Face number The radius of curvature (R) thickness Refractive index (N) Abe number Focal length
(f) Conditional expression
(| K _n / K _t |) 1st
lens
One* 1.501327 0.476034 1.528208 54 1.775262 0.900261 2* -2.224054 0.1 Second
lens
3 * -4.723653 0.25 1.63242 23.35 -2.68244 0.5958 4* 2.701372 0.131507 Third
lens
5 * 13.60569 0.519751 1.528208 54 1.191034 1.341859 6 * -0.650904 0.1 Fourth
lens
7 * 0.796609 0.22 1.528208 54 -1.53542 1.040886 8* 0.363514 0.363674

Referring to Table 3, it can be seen that the conditional expressions (| K _n / K _t |) for the first to fourth lenses are 0.900261, 0.5958, 1.341859, and 1.040886, which satisfy the conditional expressions 1 to 4 described above.

In addition, the F-number of the lens assembly 500 according to the second embodiment of the present invention shows a performance of 2.072 and the half-angle of view (HFOV) shows a performance of 45 degrees. Accordingly, it can be confirmed that a high-quality wide-angle image can be obtained through the lens assembly according to the present invention.

Table 4 below shows values of aspherical surface coefficients of the respective lenses constituting the lens assembly according to the embodiment of Table 3. [

division The first lens The second lens Third lens The fourth lens One* 2* 3 * 4* 5 * 6 * 7 * 8* alpha -2.780267 9.011465 0 -76.665484 -519.525817 -1.642208 0 0 A -0.111606 -0.765201 -1.006533 -0.082966 -0.037435 0.051272 -1.105775 -0.584554 B -0.076150 0.924554 1.278113 -0.438279 -0.094069 0.101600 0.853428 0.667397 C -9.048187 -0.981082 2.539555 1.773988 -0.358756 -0.979384 0.036782 -0.494265 D 36.883887 -10.625238 -13.365890 1.928461 1.405552 1.440825 -0.126786 0.210145 E -52.016860 13.843915 17.310331 -24.665224 5.609200 4.204256 0.042717 -0.054903 F -50.139943 26.905598 6.875056 3.036619 -21.479789 -3.262472 -0.023088 0.003378 G -45.044516 56.870132 0 0 0 0 0 0.005478 H 0 0 0 0 0 0 0 0.000582 I 0 0 0 0 0 0 0 -0.001149

FIG. 6 is a graph showing the aberration characteristics of the lens assembly according to the second embodiment of the present invention, in which astigmatic field curves and distortion are measured in order from the left.

In Fig. 6, the Y axis represents the size of the image, and the X axis represents the focal length (in mm) and distortion (in%). Generally, the closer the aberration curves are to the Y-axis, the better the aberration correction function is. Therefore, in the aberration diagram shown in Fig. 6, since the values of the images are adjacent to the Y-axis in almost all fields, it can be confirmed that both the astigmatism and the distortion aberration are excellent values.

Third Embodiment

7 is a diagram for explaining a configuration of a lens assembly according to a third embodiment of the present invention.

7, the lens according to the third embodiment of the present invention, assembly 700 includes a diaphragm (S _top in the order from the object side, The first lens 710, the second lens 720, the third lens 730, the fourth lens 740, the infrared filter 750, and the image sensor 230 are disposed.

The aperture (S _top , 705 are located at the forefront portion of the lens assembly 700 (i.e., the front portion of the first lens) to adjust the amount of light incident on the optical system. Meanwhile, in another embodiment, a diaphragm 705 may be disposed between the lens and the lens.

The first to fourth lenses 710, 720, 730, and 740 may be formed of a plastic material having a predetermined refractive index. Also, the first to fourth lenses 710, 720, 730, and 740 may use aspheric lenses on at least one side or both sides.

The first lens 710 has a positive refractive power, and the object side surface S1 is formed convexly. A diaphragm 705 is disposed on the object side surface S1 of the first lens 710. [

The second lens 720 has a negative refracting power, and the object side surface S3 is concave. The distance between the lens assembly 700 and the image sensor 230 is increased by increasing the size of the incident angle CRA incident on the imaging surface by arranging the lens having the negative refracting power at the second position from the object side So that a sufficient size image can be obtained despite the shortness. In order to further increase the size of the incident angle CRA through the second lens 720, a high refractive index plastic material having a refractive index of 1.6 or more may be used for the second lens 720.

The third lens 730 has a positive refractive power, and the upper side S6 is convex. The fourth lens 740 has a negative refractive power. As shown in the figure, the fourth lens 740 may have an aspherical shape in which the object side surface S7 and the upper surface side S8 both have inflection points.

As described above, the lens assembly 700 having the structure of the PNPN (+ - + -) has the overall slim structure due to the lenses having negative refractive power.

Also, the lens assembly 700 increases the size of the incident angle CRA incident on the imaging surface by using the second lens 720 and the fourth lens 740 having a negative refractive power. Accordingly, it is possible to realize a high-quality wide-angle image even if the distance between the lens assembly 700 and the image sensor 230 is short.

The infrared filter 750 is disposed between the fourth lens 740 and the image sensor 230 and functions to block radiant heat emitted from external light from being transmitted to the image sensor 230. In addition, the infrared filter 750 functions to transmit visible light and reflect the infrared light to the outside. Meanwhile, in another embodiment, the infrared filter 750 may be configured in the form of a coating film, and may be attached to the upper surface S8 of the fourth lens 740. [

The image sensor 230 converts an optical signal incident through the diaphragm 705, the first through fourth lenses 710, 720, 730, and 740 and the infrared filter 750 into an electrical signal.

Table 5 shows the first to fourth lenses constituting the lens assembly according to the third embodiment of the present invention. At this time, the first to fourth lenses are designed to satisfy the above-mentioned conditional expressions.

lens Face number The radius of curvature (R) thickness Refractive index (N) Abe number Focal length
(f) Conditional expression
(| K _n / K _t |) 1st
lens
One* 1.463959 0.481215 1.528208 54 1.830783 0.875363 2* -2.52524 0.1 Second
lens
3 * -5.024676 0.25 1.63242 23.35 -2.63953 0.607153 4* 2.547946 0.122154 Third
lens
5 * 11.27826 0.526392 1.528208 54 1.157755 1.384231 6 * -0.636165 0.1 Fourth
lens
7 * 0.783653 0.22 1.528208 54 -1.51864 1.055287 8* 0.357935 0.374201

Referring to Table 5, it can be confirmed that the conditional expressions (| K _n / K _t |) for the first to fourth lenses are 0.875363, 0.607153, 1.384231 and 1.055287, which satisfy the conditional expressions 1 to 4 described above.

In addition, the F-number of the lens assembly 700 according to the third embodiment of the present invention shows a performance of 2.081, and the half-angle of view (HFOV) shows a performance of 45 degrees. Thus, it can be seen that a high-quality wide-angle image can be obtained through the lens assembly 700 according to the present invention.

Table 6 below shows values of aspherical surface coefficients of the respective lenses constituting the lens assembly according to the embodiment of Table 5. [

division The first lens The second lens Third lens The fourth lens One* 2* 3 * 4* 5 * 6 * 7 * 8* alpha -2.412248 10.564366 0 -91.866871 -1495.182087 -1.682164 -15.650706 -3.3730461 A -0.098721 -0.811134 -1.115702 -0.085739 -0.004521 0.065966 -0.969116 -0.583085 B 0.006055 0.748925 1.301577 -0.486642 -0.040137 0.132486 0.710333 0.684884 C -8.935707 -0.637424 2.352837 1.823431 -0.402337 -0.956191 0.001015 -0.507788 D 34.663660 -10.694062 -13.788244 2.139305 1.218951 1.429777 -0.111003 0.205983 E -51.912007 9.974944 17.518083 -24.678857 5.531912 4.082908 0.070902 -0.053768 F -34.780400 18.741528 10.182857 2.430749 -21.200690 -3.538725 -0.001256 0.004747 G -45.044516 58.789362 0 0 -15.20209677 -3.1361102 -0.0064628 0.006057 H 0 0 0 0 0 0 0 0 I 0 0 0 0 0 0 0 0

FIG. 8 is a graph showing aberration characteristics of a lens assembly according to a third embodiment of the present invention, and is a graph showing astigmatic field curves and distortion in order from the left.

8, the Y axis means the size of the image, and the X axis means the focal length (in mm) and distortion (in%). Generally, the closer the aberration curves are to the Y-axis, the better the aberration correction function is. Therefore, in the aberration diagram shown in Fig. 8, since the values of the images are adjacent to the Y-axis in almost all fields, it can be confirmed that both the astigmatism and the distortion aberration are excellent values.

In the present specification, three lens assemblies satisfying the above-described conditional formulas are exemplified and described in detail, but it should be understood that various embodiments consistent with the above-described conditional expressions may be implemented. It will be self-evident.

As described above, the lens assembly according to various embodiments of the present invention is mounted on the camera module disposed on the front surface of the terminal body, thereby realizing a high-quality wide-angle image while slimming the camera module.

The present invention described above can be embodied as computer-readable codes on a medium on which a program is recorded. The computer readable medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, , And may also be implemented in the form of a carrier wave (e.g., transmission over the Internet). Also, the computer may include a control unit 180 of the terminal. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

300: lens assembly 305: diaphragm
310: first lens 320: second lens
330: third lens 340: fourth lens
350: Infrared filter 230: Image sensor

Claims (13)

In order from the object side
A diaphragm for adjusting the amount of light incident on the optical system;
A first lens having positive refractive power;
A second lens having a negative refractive power;
A third lens having positive refractive power; And
And a fourth lens having a negative refractive power. The method according to claim 1,
Wherein the first lens has a convex surface on an object side. The method according to claim 1,
Wherein the second lens has a concave object side surface. The method according to claim 1,
And the third lens is formed such that the upper side thereof is convex. The method according to claim 1,
Wherein the second lens is formed of a high refractive index plastic material having a refractive index of 1.6 or more. The method according to claim 1,
Wherein the first, third, and fourth lenses are formed of a high refractive index plastic material having a refractive index of 1.5 or more. The method according to claim 1,
Wherein at least one of an object side surface and an upper side surface of the first through fourth lenses is an aspherical surface. The method according to claim 1,
And an infrared filter disposed on an upper surface of the fourth lens to block infrared rays of light incident on the image sensor. The method according to claim 1,
Wherein the first lens satisfies the following condition (1).
[Conditional expression 1]
0.5 < K ₁ / K _t < 1.0
Here, K ₁ is the refractive power of the first lens, and K _t is the refractive power of the entire lens. The method according to claim 1,
Wherein the second lens satisfies the following condition (2).
[Conditional expression 2]
0.3 < K ₂ / K _t < 1.0
Here, K ₂ is the refractive power of the second lens, and K _t is the refractive power of the entire lens. The method according to claim 1,
Wherein the third lens satisfies the following condition (3).
[Conditional expression 3]
1.0 < K ₃ / K _t | < 1.5
Here, K ₃ is the refractive power of the third lens, and K _t is the refractive power of the entire lens. The method according to claim 1,
Wherein the fourth lens satisfies the following condition (4).
[Conditional expression 4]
0.5 < K ₄ / K _t < 1.3
Here, K ₄ is the refractive power of the fourth lens, and K _t is the refractive power of the entire lens. A camera module comprising a lens assembly according to any one of claims 1 to 12.

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