KR20050033308A - Zoom camera using the liquid lens for mobile phone, control system and method thereof - Google Patents

Abstract

A zoom camera of a mobile terminal using a liquid lens, a system for controlling the zoom camera and a method of controlling the zoom camera are provided to realize a zoom function of the zoom camera by using small space. The first lens group(310) is comprised of the first lens(311) having a positive refraction index and the second lens(312) having a negative refraction index, wherein the first and second lenses are placed sequentially from an object. The first liquid lens(300), placed apart from the first lens group by a predetermined interval, varies curvature radius of the contact surface between conductive liquid and nonconductive liquid according to a zoom function control signal so as to provide a zoom function of a camera. The second lens group(330) is placed apart from the liquid lens by a predetermined interval and comprised of the third lens(331) having the positive refraction index and both aspheric surfaces and the fourth lens(332) having the negative refraction index and both aspheric surfaces. An IR(Infrared Ray) filter(340), placed apart from the second lens group by a predetermined interval, filters infrared-ray wavelength incident from an optical system so as to protect an image plane.

Description

Zoom camera using the liquid lens for mobile phone, control system and method

The present invention relates to a zoom camera of a portable terminal, a control system and a control method thereof. More specifically, a zoom camera of a portable terminal using a liquid lens that is installed by combining a liquid lens and a fixed lens in series on the inner surface of the outer barrel and changing the curvature radius of the liquid lens so that the zoom function of the camera can be realized. A control system and a control method thereof.

Recently, the trend of distributing portable terminal products in which cameras are integrated in portable terminals such as mobile phones and PDAs to consumers has become a mainstream, and such cameras attach a lens to an image pickup device such as ccd or cmos to target a subject. And to capture the captured subject data through a predetermined recording medium.

In the case of a lens system mounted on a portable terminal as described above and used to photograph a subject, the following conditions must be satisfied.

In other words, in order to have mega pixel camera performance, the pixel size of the image pickup device has many sizes less than 4um, so the lens design itself should be designed to have sufficient resolution, and the design should be made larger than the actual sensor size in consideration of the assembly tolerance. do.

In addition, in addition to the above-described conditions of resolution, TV distortion should have a performance of 1% or less. The lower the resolution, the more the distortion is corrected, so the TV distortion is preferably 1% or less.

In addition, since the ambient light amount of the portable terminal is due to the angle of light incident on the sensor and the ambient light ratio of the lens system itself, the amount of ambient light of the camera is improved when the sensor is designed at an angle that allows the incident.

If the angle is designed to be smaller than the desired angle, resolution, distortion, and the length of the optical system are deteriorated, causing problems in combination with the sensor.

In addition, in the case of a lens system mounted on a portable terminal as described above and used for imaging a subject, various kinds of shapes or shapes of the subject are deformed by the influence of incident light having different kinds of wavelengths input at the time of imaging the subject. Aberrations such as spherical aberration, astigmatism and distortion aberration are generated, and should be configured to suppress the occurrence of such aberration.

Here, spherical aberration (axial aberration) is a chromatic aberration in which the image of the subject cannot be completely reproduced based on the wavelength of light when the image of the subject is made in a lens or a spherical mirror, and the like. It is called spherical aberration of meaning, and the aberration that occurs because the shop made from the beam of light from one point on the optical axis depends on which part of the lens the beam has passed through It is called.

Distortion aberration is a phenomenon in which a straight portion of a subject is bent to form an image, and the subject is bent inward like a failure or outward as a barrel, and the magnification of each part of the subject increases in proportion to the distance, but the overall image is proportional. This happens because it cannot change.

In addition, astigmatism is one of spherical aberrations of a broad meaning, and refers to a phenomenon in which an image of a material point distant from a main axis becomes blurry in a ring shape or a radial shape without becoming a perfect point.

On the other hand, zoom has a variable focal length (variable-focal length), mainly having a front lens having a positive refractive index and a rear lens having a negative refractive index and these lenses by their relative movement Zooming is achieved by adjusting the distance between cameras. In general, cameras, etc., change the focal length of the lens to convert it to a wide-angle lens or a telephoto lens so that the user can have various viewing angles in one place without moving. It adopts the structure concerned.

Such zoom can be roughly divided into optical zoom and digital zoom. Optical zoom refers to a zoom that uses an optical lens and moves the optical lens relatively to enlarge a subject with a variable focal length. It is a zoom that magnifies an image in a charge-coupled device (CCD), independent of the optical lens, such as magnifying an image in a graph program such as photo shovel or ACDSee.

The digital zoom has an advantage in miniaturization and thinning because the digital zoom enlarges an image in a CCD, unlike an optical zoom, and thus does not require a space due to a focal length change such as an optical zoom. Since the zoom is realized by changing the focal length, the space required by the change of the focal length is required to be larger than the digital zoom, but the sharp resolution can be realized when zooming. Generally, optical zoom that can realize high resolution is preferred to consumers over digital zoom.

In addition, the camera attached to the above-described portable terminal is equipped with a zoom function that can enlarge and photograph the subject by changing the lens focus to satisfy various needs of consumers.

However, portable terminals that have been developed and are being distributed so far in accordance with the trend of miniaturization and thinning are using a digital zoom that can be made more compact because the space according to the change of focal length is not secured. It is not using optical zoom that requires more space.

However, as described above, research to realize a high resolution zoom in a portable terminal is urgently needed to meet the consumer's desire for high resolution.

In accordance with such a need, Korean Patent Application No. 2002-5397 "A device and method for controlling a zoom lens of a camera in a mobile communication terminal" switches to a camera mode when a signal is requested to switch to a camera mode, and sets the zoom lens up or down. When a signal is requested to move in the direction, the zoom lens is controlled to move up or down, and when a signal is required to move in the left or right direction, it is controlled to move in the left or right direction. Or a zoom camera is disclosed that controls to move the zoom lens in the forward or backward direction when a report requesting the movement in the backward direction is detected.

In addition, in Korean Patent Application No. 2003-3948, "The barrel structure and the zoom assembly of a zoom camera", the optical zoom is applied to a portable terminal by improving the conventional barrel structure of an optical zoom applied to a digital camera. A barrel structure and a zoom assembly of an easy and high resolution optical zoom lens have been proposed.

The proposed “camera barrel structure and zoom assembly” includes a front lens unit and a rear lens unit having negative refractive indices arranged in the order of the subject, and a helicoid groove for guiding the helicoid locus motion of the front lens unit and the rear lens unit. There is provided a barrel structure of a zoom camera including an inner barrel formed therethrough and an outer barrel inserted into the outside of the inner barrel and guided to guide the vertical movement of the front and rear lens portions, the outer barrel formed on the inner surface thereof.

In addition, the proposed “barrel structure and assembly of the zoom camera” includes: a) an inner barrel through which a prepared front lens portion and a rear lens portion, and a helicoid groove for guiding a helicoid trajectory movement of the front and rear lens portions; Inserted to the outside of the inner barrel and the escape groove for guiding the vertical movement of the front and rear lens portion is formed on the inner surface, the outer barrel assembly consisting of an outer barrel formed of gears on the outer surface, b) one side of the drive motor with gears on the rotating shaft A zoom assembly of a zoom camera is provided, which includes a base having an opening through which an image of a subject can pass, and c) a substrate on which an image sense is mounted to focus the image of the subject. .

However, the zoom camera according to the prior art has a problem that the zoom device occupies a large amount of space in the camera for the zoom function through the movement of the lens in the barrel.

In addition, the zoom camera according to the related art has a problem in that a large power consumption is generated by using a motor as a driving method for moving the lenses in the barrel.

Therefore, in order to be equipped with a zoom function in a camera for a mobile communication terminal in recent years, the size and power consumption have to be small, but it is difficult to apply a zoom camera using a conventional motor.

The present invention has been made to solve the above problems, and to provide a zoom camera, a control system and a control method of a portable terminal using a liquid lens to implement a zoom function of the camera using a small space and its object It is done.

Another object of the present invention is to provide a zoom camera of a portable terminal using a liquid lens, a control system thereof, and a method of controlling the same so as to quickly respond to a user's zoom function request and satisfy a user's demand at a high speed. .

Another object of the present invention is to provide a zoom camera of a portable terminal using a liquid lens, a control system thereof, and a control method thereof, which can realize a zoom function of a camera while minimizing power loss of a battery mounted in the portable terminal. do.

The present invention for achieving the above object is a first lens group consisting of a first lens having a positive refractive index and a second lens having a negative refractive index in order from the object side; A liquid lens disposed at a predetermined interval from the first lens group and configured to change a radius of curvature of the contact surface between the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; A second lens group disposed from the liquid lens at a predetermined interval, the second lens group including a third lens having a positive refractive index of which both surfaces are aspherical and a fourth lens having a negative refractive index of both the aspherical surface; And an IR filter disposed at a predetermined interval from the second lens group and filtering an infrared wavelength incident to the optical system to protect an image plane.

In addition, the present invention provides a light source comprising: a first lens group including a first lens having a positive refractive index and a second lens having a negative refractive index in order from the object side; A second lens group disposed from the first lens group at a predetermined interval, the second lens group including a third lens having a positive refractive index having both surfaces aspherical and a fourth lens having a negative refractive index having both surfaces aspheric; A liquid lens positioned between the third lens and the fourth lens of the second lens group to change a radius of curvature of the contact surface of the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; And an IR filter disposed at a predetermined interval from the second lens group and filtering an infrared wavelength incident to the optical system to protect an image plane.

In addition, the present invention provides a zoom camera having a liquid lens performing a zoom function in series with a lens having a negative refractive index to change the radius of curvature of the contact surface of the conductive liquid and the non-conductive liquid in accordance with the zoom function control signal to perform a zoom function Structures; A controller configured to change a curvature radius of the liquid lens and generate a zoom function control signal when a signal for requesting a front and rear zoom function is detected; And a zoom function adjusting unit configured to change a curvature radius of the contact surface between the conductive liquid and the non-conductive liquid by changing the voltage applied to the liquid lens when the zoom function control signal is input from the control unit.

In addition, the control unit comprises the steps of switching to the camera mode when a signal for requesting the switch to the camera mode is detected; Generating a zoom function control signal when a signal for requesting a change in curvature of the zoom lens is detected; And performing a zoom function by changing a radius of curvature of the liquid lens by the zoom function adjusting unit according to the zoom function control signal of the controller.

In addition, the present invention includes a first lens group consisting of a first lens having a predetermined refractive index and a second lens having a predetermined refractive index in order from the object side; A first liquid lens disposed at a predetermined distance from the first lens group and configured to change a radius of curvature of a contact surface of the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; A second lens group disposed from the first liquid lens at a predetermined interval, the second lens group including a third lens having a positive refractive index of which both surfaces are aspherical and a fourth lens having a negative refractive index of both the aspherical surface; And an IR filter disposed at a predetermined interval from the second lens group and filtering an infrared wavelength incident to the optical system to protect an image plane.

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

1 is a cross-sectional view showing the structure of a liquid lens used in the present invention.

Referring to the drawings, the liquid lens used in the present invention seals the conductive fluid 140 and the non-conductive fluid 150 which are not mixed with each other by using the sealing cylinder 130 and the front and rear panels 110 and 120. .

Here, the front and rear panels 110 and 120 may be a plastic or glass product as a transparent body.

The first insulator 111 is attached to the front panel 110, and the attached first insulator 111 maintains contact with the conductive liquid 140.

In addition, a second insulator 121 is attached to the rear panel 150 to maintain contact with the non-conductive liquid 150.

The reason why the shape of the second insulator 121 is different from the shape of the first insulator 111 is that the contact area with the nonconductive liquid 150 is large because the non-conductive liquid 150 maintains surface tension with the nonconductive liquid 150. In order to prevent the position of the 150 and the conductive liquid 140 is reversed.

In addition, water is mainly used for the conductive liquid 140, and the conductive liquid 140 and the non-conductive liquid 150 have the same specific gravity and do not mix with each other.

When a voltage is applied between the conductive liquid 140 and the nonconductive liquid 150, the contact surfaces of the two fluids are changed to have a specific curvature to perform a zoom function and a focus control function.

This is based on the phenomenon of electrowetting, which has recently gained much attention as a new research technique.

The electrowetting phenomenon refers to a phenomenon in which the contact angle of the droplet is changed when the electrolyte droplet is placed on the electrode coated with the insulator as shown in FIG.

The relationship between the externally applied voltage and the contact angle in the electrowetting phenomenon is explained by the following Lippmann-Young equation.

The method of controlling the microfluid and the microparticles in the fluid using the electrowetting phenomenon has the following advantages.

1) As it is basically a method using an electric field, electrical wiring and electrodes can be manufactured integrally with a biochip or a microflow device.

2) It is possible to transfer the micro fluid at high speed of about 1cm / s.

3) Control of fluid behavior with relatively low voltage (1V ~ 100V) and low power consumption.

4) Droplets can be reversibly controlled and hysteresis is low.

Due to these advantages, it can be applied to many fields such as microfluidic transfer, increasing mixing and coating speed, optical switch, etc. and recently, many researches for this in the world of microelectromechanical systems (MEMS) and microfluidics (microfluidics) there is a binary row (year).

In Korea, a lot of investments are being made in MEMS, biotechnologies, and nanotegridges, and the demand for electrowetting in the mechanical engineering field is expected to increase significantly.

The basic principle of this phenomenon is G. Beni et al. Published the `` Continuous electrowetting effect '' paper published in May 1982 by Appl. Phys. Lett, Vol. 912, and by J. Lee and J. Lee in 2000. This is described in the paper Surface tension driven microactuation based on continuous electrowetting (CEW), published in Journal of Microelectromechanical Systems, Vol. 198, p. 171.

Globally, there was an example of applying the electrowetting phenomenon to the display in the 1980s, but full-scale application research began in the 1990s. First, Professor Pollack of the Department of Electrical Engineering, Duke University, USA, used electrowetting of droplets between the micro-gaps of parallel plates to induce surface tension differences between the two ends of the droplets. Devised. Professor Kim Chang-jin, a professor of UCLA mechanical engineering, has developed a micromotor using mercury that can rotate about 2.8V to 420rpm using a similar concept.

Next, Prins et al., Philips, controlled the flow inside the microchannel array using electrowetting.

Berge & Peseux then applied electrowetting to control the liquid lens described above. Blake et al. Of Kodak European R & D applied electrowetting to control the contact angle to increase the coating critical velocity at which bubbles begin to be sucked into thin films.

3 is a cross-sectional view of a zoom camera of a portable terminal using a liquid lens according to an embodiment of the present invention.

Referring to the drawings, a zoom camera of a portable terminal using a liquid lens according to an embodiment of the present invention, the first liquid lens 300 to perform the focus adjustment function from the object side, the first lens group 310 having a positive refractive index ), A second liquid lens 320 that performs a zoom function, a second lens group 330 having a positive refractive index, and an IR filter 340.

Here, the first liquid lens 300 is changed to have a specific curvature of the contact surface of the two fluids by the external voltage change to perform the auto focus adjustment function.

The first lens group 310 includes a first lens 311 having a positive refractive index and a second lens 312 having a negative refractive index, and the first lens 311 and the second lens 312 are manufactured. The first lens 311 is a glass lens made of glass, and the second lens 312 is a plastic lens made of plastic.

Next, the second liquid lens 320 serves as a front lens in the zooming function by making the contact surface of the two fluids have a specific curvature due to an external voltage change. That is, the radius of curvature changes as the contact surface changes due to a voltage change applied from the outside, thereby performing a zoom function to enlarge a distant object.

The second lens group 330 includes a third lens 331 having both surfaces having a positive refractive index aspherical and a fourth lens 332 having both surfaces having a negative refractive index aspheric, and the third lens 331 and the third lens having a negative refractive index. The four lenses 332 are plastic lenses made of plastic.

Meanwhile, although the second liquid lens 320 is positioned in front of the third lens 331, the second liquid lens 320 may be positioned in front of the fourth lens 332.

In addition, the second liquid lens 320 is positioned at the front end of the third lens 331 of the second lens group 330, and the same function as that of the second liquid lens 320 is separately provided at the front end of the fourth lens 332. A third liquid lens (not shown) to perform may be implemented.

In addition, a fifth lens having a negative refractive index may be further provided at a rear end of the fourth lens 332, and the second liquid lens 320 may be positioned in front of the provided fifth lens. In addition, a third liquid lens (not shown) may be separately provided so that the third liquid lens is positioned in front of the lenses 331 and 332 having negative refractive indices.

In addition, the present invention is implemented so that the first liquid lens 300 having an autofocus function is located in front of the first lens group 310, but separately the second liquid lens 320 without inserting the first liquid lens 300. In this case, the zoom function can be implemented. In this case, the auto focus function is not provided.

4 is a block diagram illustrating an internal configuration of a mobile communication terminal equipped with a zoom function according to an embodiment of the present invention.

Referring to FIG. 4, the controller 411 controls the overall operation of the mobile communication terminal. The memory 413 stores control programs generated according to the control program of the mobile communication terminal and the control of the controller 411.

The key input unit 415 includes a plurality of dialing keys, a MENU key, a navigation key, a side key, a SEND key, and an END key. The menu key includes a camera mode key. In general, the navigation key is a key for performing menu selection, deletion, storage, and the like, and the side key is used as a key for adjusting a volume tone, a belt tone, and the like.

However, the side keys are manipulated to move the zoom lens of the mobile communication camera in the front and back directions. In the present invention, the side keys mean the front and rear direction keys. A key signal corresponding to the key selected by the user is generated and transmitted to the controller 411.

The voice memory 417 stores a plurality of voice messages, and the voice processor 419 analog-processes voice messages derived from the voice memory 417 and transmits them through a speaker under the control of the controller 411. In addition, the digital signal processing analog voice input from the user through the microphone.

The transmitter 421 receives a signal generated by the controller 411, digitally modulates the signal, and transmits the signal to the duplexer 423. The duplexer 423 transmits a wireless signal received from the transmitter 421 through an antenna and transmits a signal received through the antenna to the receiver 125. The receiver 425 demodulates a radio signal received from the duplexer 423 and transmits the demodulated signal to the controller 411. The controller 411 controls the call in response to the received signal.

The display unit 427 is implemented with a liquid crystal display unit (LCD), a light emitting diode (LED), or the like, and displays a control signal and an input signal of the mobile communication terminal performed under the control of the controller 411.

The camera adjuster 431 includes a focus adjuster 510, a zoom adjuster 520, and the like, as shown in FIG. 5 for automatically adjusting the focus by adjusting the first liquid lens, and the controller to adjust the composition of the subject. It operates in accordance with the control signal of 411.

FIG. 5 is a block diagram illustrating an internal block of the camera controller of FIG. 4, which includes a focus adjuster 510 and a zoom adjuster 520.

Here, the focus adjuster 510 automatically adjusts the voltage applied to the first liquid lens to focus.

In addition, the zoom adjuster 520 performs a zoom function by changing the curvature of the contact surface of the second liquid lens in accordance with a control signal of the controller 411 to compose the subject.

So far, the internal configuration of the camera unit has been described, and a process of controlling the camera unit will be described.

6 is a flowchart illustrating a process of controlling a zoom camera according to an embodiment of the present invention.

In step 110, the controller checks whether a key signal is input from the key input unit. If the test result indicates that the key signal is not the camera mode key, the initial state is maintained. If the key signal is the camera mode key, the controller proceeds to step 120. In step 120, the controller switches to the camera mode and proceeds to step 130.

In step 130, the controller controls the focus adjusting unit to automatically adjust focus to provide an auto focus function.

In operation 140, when the key signal input from the key input unit is the forward zoom function key or the backward zoom function key, the controller provides a zoom function by adjusting the radius of curvature of the contact surface of the second liquid lens.

In operation 160, the controller checks whether a key signal is input from the key input unit. If the result of the inspection is that the key signal is not the camera mode end key, the controller repeatedly performs steps 130 to 160, and terminates when the key signal is the camera mode end key.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, according to the zoom camera and the control method using the liquid lens according to the present invention, there is an effect to reduce the power consumption used for the zoom operation in the camera of the portable terminal.

Further, according to the present invention, the zoom function can be implemented even in a state where the barrel of the camera of the portable terminal is reduced, thereby miniaturizing the portable terminal.

In addition, according to the present invention, there is an effect that the zoom performance is improved than the performance by the implementation of the zoom function by the movement of the conventional lens.

1 is a cross-sectional view showing the structure of a liquid lens used in the present invention.

2 is a view for explaining the electrowetting phenomenon.

3 is a cross-sectional view of a zoom camera of a portable terminal using a liquid lens according to an embodiment of the present invention.

4 is a block diagram illustrating an internal configuration of a mobile communication terminal equipped with a zoom function according to an embodiment of the present invention.

5 is a block diagram illustrating an internal block of the camera adjusting unit of FIG. 4.

6 is a flowchart illustrating a method of controlling a zoom camera according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

110, 120: panel 111, 121: insulator

130: cylinder 140: conductive liquid

150: non-conductive liquid 300, 320: liquid lens

310, 330: solid lens group 340: IR filter

411 control unit 431 camera control unit

510: focus adjuster 520: zoom adjuster

Claims (10)

A first lens group consisting of a first lens having a positive refractive index and a second lens having a negative refractive index in order from the object side; A first liquid lens disposed at a predetermined distance from the first lens group and configured to change a radius of curvature of a contact surface of the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; A second lens group disposed from the first liquid lens at a predetermined interval, the second lens group including a third lens having a positive refractive index of which both surfaces are aspherical and a fourth lens having a negative refractive index of both the aspherical surface; And A zoom camera of a portable terminal using a liquid lens, which is disposed spaced apart from the second lens group by a predetermined interval, and includes an IR filter that filters an infrared wavelength incident to an optical system to protect an image plane. The method of claim 1, And a second liquid lens positioned at the front end of the first lens group to change the curvature radius of the contact surface of the conductive liquid and the non-conductive liquid according to the focus adjustment control signal to provide a focus adjustment function. Zoom camera of a portable terminal using a lens. The method according to claim 1 or 2, A third liquid lens positioned at a front end of the fourth lens of the second lens group to change a radius of curvature of a contact surface of the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; Zoom camera of a portable terminal using a liquid lens, characterized in that made. A first lens group consisting of a first lens having a positive refractive index and a second lens having a negative refractive index in order from the object side; A second lens group disposed from the first lens group at a predetermined interval, the second lens group including a third lens having a positive refractive index of which both surfaces are aspherical and a fourth lens having a negative refractive index of which both surfaces are aspherical; A first liquid lens positioned between the third lens and the fourth lens of the second lens group to change a radius of curvature of a contact surface of a conductive liquid and a non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera ; And A zoom camera of a portable terminal using a liquid lens disposed at a predetermined interval from the second lens group and including an IR filter for filtering an infrared wavelength incident to an optical system to protect an image plane. The method of claim 4, wherein And a second liquid lens positioned at the front end of the first lens group to change the curvature radius of the contact surface of the conductive liquid and the non-conductive liquid according to the focus adjustment control signal to provide a focus adjustment function. Zoom camera of a portable terminal using a lens. A zoom camera structure including a first liquid lens for performing a zoom function in series with a lens having a negative refractive index and changing a radius of curvature of a contact surface between the conductive liquid and the non-conductive liquid according to a zoom function control signal to perform a zoom function; A controller configured to change a curvature radius of the first liquid lens to generate a zoom function control signal when a signal for requesting a front and rear zoom function is detected; And a zoom function adjusting unit configured to change a curvature radius of the contact surface between the conductive liquid and the non-conductive liquid by changing the voltage applied to the first liquid lens when the zoom function control signal is input from the control unit. Control device of the zoom camera used. The method of claim 6, The zoom camera structure further includes a second liquid lens positioned at a front end of the lens having a positive refractive index and performing a focus function by changing a radius of curvature of the contact surface between the conductive liquid and the non-conductive liquid according to a focus function control signal. The controller monitors the focus state of the zoom camera structure and generates a focus adjustment control signal when the focus is not achieved. And a focus function adjusting unit configured to change a curvature radius of the contact surface between the conductive liquid and the non-conductive liquid by changing the voltage applied to the second liquid lens when the focus function control signal is input from the control unit. Control device of the zoom camera used. The control unit switches to the camera mode when a signal for requesting the switch to the camera mode is detected; Generating a zoom function control signal when a signal for requesting movement of the zoom lens back and forth is detected; And And a zoom function adjusting unit changing the curvature radius of the liquid lens in accordance with the zoom function control signal of the controller to perform a zoom function. The method of claim 8, After the step of switching to the camera mode, the control unit checking the focus state of the camera; The control unit generating a focus function control signal when the focus is not focused; And And a focus function adjusting unit changing the curvature radius of the liquid lens to perform a focus function according to the focus function control signal of the controller. A first lens group consisting of a first lens having a predetermined refractive index and a second lens having a predetermined refractive index in order from an object side; A first liquid lens disposed at a predetermined distance from the first lens group and configured to change a radius of curvature of a contact surface of the conductive liquid and the non-conductive liquid according to a zoom function control signal to provide a zoom function of the camera; A second lens group disposed from the first liquid lens at a predetermined interval, the second lens group including a third lens having a positive refractive index of which both surfaces are aspherical and a fourth lens having a negative refractive index of both the aspherical surface; And A zoom camera of a portable terminal using a liquid lens disposed at a predetermined interval from the second lens group and including an IR filter for filtering an infrared wavelength incident to an optical system to protect an image plane.