KR20090103483A - Small zoom optical system and capsule endoscope using thereof - Google Patents

Abstract

PURPOSE: A small zoom optical system and a capsule endoscope using the same are provided to obtain an image with high quality in the abdominal cavity. CONSTITUTION: A small zoom optical system includes a first lens group(100), a second lens group(110), and a third lens group(120). The first lens group has a negative refractive index from an object. The second lens group has a positive refractive index. The third lens group has the positive refractive index. The second lens group is comprised of three sheets of lenses.

Description

Small zoom optical system and capsule endoscope using the same {SMALL ZOOM OPTICAL SYSTEM AND CAPSULE ENDOSCOPE USING THEREOF}

The present invention relates to a compact zoom optical system and a capsule endoscope using the same.

Endoscopy is an implantable medical device originally designed to observe organs that cannot be seen directly without surgery or autopsy.

However, endoscopy is due to the pain and discomfort associated with the test, many patients have to avoid the endoscopy and receive medication instead. In particular, endoscopes have been used for many diagnosis and examinations, but because of the size and stiffness of the catheter, it has caused various inconveniences to patients and medical staff.

Accordingly, capsule type endoscopes have been developed to supplement various disadvantages of endoscopes and are being used to diagnose various diseases in the medical field.

Capsule type endoscope, or capsule type endoscope, is an ingestible capsule size endoscope that is swallowed through the oral cavity of the human body and moves in accordance with the peristalsis of the digestive system, which is one of the body cavities of the human body, after taking an image of the digestive system. The photographed image information is transmitted to an external device through wireless communication.

These capsule endoscopes do not require anesthesia, do not have a nausea, and can shoot up to the small intestine that could not be taken with a conventional endoscope, there is an advantage that allows a more precise medical diagnosis.

The above-mentioned capsule endoscope includes a lighting unit that greatly illuminates the inside of the body cavity, an image obtaining unit which acquires an image and transmits the obtained image, and a power supply unit which supplies power to the lighting unit and the image obtaining unit, wherein the lighting unit It is composed of a case including an optical cap positioned in the front end and the optical cap coupled to the optical cap.

In general, the capsule endoscope employs optical elements such as CMOS and CCD as means for acquiring an image, and an optical system including the optical element is used.

The optical system included in such a capsule endoscope requires the following conditions.

First, it must be a bright lens. The reason for this is that there is a characteristic of taking an object regardless of the surrounding environment, and a bright lens is required in order to be able to take an object even in a place where light is low.

Second, the part margin should be increased as small as possible.

Third, high resolution must be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a compact zoom optical system and a capsule endoscope using the same, which can obtain a small and bright lens and high resolution.

It is also an object of the present invention to provide a small zoom optical system and a capsule endoscope using the same that can realize a zoom function to a small size.

A compact zoom optical system according to the present invention for achieving the above object is composed of a first lens group having a negative refractive index from the object side, a second lens group having a positive refractive index, a third lens group having a positive refractive index, The second lens group is composed of three lenses, and satisfies the following conditional expression.

<Conditional expression>

2.7≤d ₂ /WFno≤3.0

0.5≤φ _t / φ ₃ ≤1.5

Here, d ₂ represents the zoom movement amount of the second lens group, WFno represents the F number of the wide-angle end, φ _t represents the total refractive index of the telephoto end, and φ ₃ represents the refractive index of the third lens group, respectively.

In this case, the second lens group includes at least one positive and negative splicing lens, and is composed of positive, positive and negative lenses from an object side to an image side, and at least one of the positive lenses is an aspherical surface.

In addition, at least one of the lenses constituting the first lens group or the second lens group is an aspherical lens.

The capsule endoscope according to the present invention for achieving the above object is an illumination unit for illuminating the living body, an imaging unit for imaging the area illuminated by the illumination unit, an objective optical system located in front of the imaging unit, and the imaging A capsule endoscope including a transmission unit for transmitting the image information captured by the unit to the outside of the body, wherein the objective optical system uses the above-mentioned small zoom optical system.

Here, the capsule endoscope further comprises an infrared filter, using the human body communication to the medium or the electric field communication using the medium.

Since the small zoom optical system according to the present invention is configured to be suitable for a photographing optical system using an imaging device such as a CCD or a CMOS, there is an effect that it can contribute to miniaturization and thinning.

In addition, the capsule endoscope using the small zoom optical system according to the present invention provides an effect that can obtain a good image in the body cavity.

1 is a view showing lens positions at the wide-angle end, the middle end, and the telephoto end of the compact zoom lens according to the first embodiment of the present invention, respectively.

2A is a view showing longitudinal spherical aberration, image curvature, and distortion aberration at the wide-angle end of the compact zoom lens according to the first embodiment of the present invention.

2B illustrates longitudinal spherical aberration, image curvature, and distortion aberration at a telephoto end of a zoom lens according to a first embodiment of the present invention.

3 is a view showing a small zoom lens according to a second embodiment of the present invention.

4A is a view showing longitudinal spherical aberration, image curvature, and distortion aberration at the wide-angle end of the small zoom lens according to the second embodiment of the present invention.

4B is a view showing longitudinal spherical aberration, image curvature, and distortion aberration at the telephoto end of the compact zoom lens according to the second embodiment of the present invention.

5 is a view illustrating a capsule endoscope using a small zoom lens according to an embodiment of the present invention.

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

1: aperture 2: infrared filter

11a, 11b: transmitting electrode 12: lighting device

13 lens 14 CMOS image sensor

15 battery 16 output line

17: light window 18: housing

100: first lens group 110: second lens group

120: third lens group 131: infrared filter

132: Cabbaglas

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

1 is a layout view of a wide end, an intermediate end, and a telephoto end of a small zoom optical system according to an exemplary embodiment of the present invention, respectively. The compact zoom optical system according to the present invention includes a first lens group 100 having a negative refractive power sequentially from an object side O to an image side I, a second lens group 110 having a positive refractive power, and a positive It is composed of a third lens group 120 having refractive power. When shifting, the distance between the first lens group 100 and the second lens group 110 decreases, and the distance between the second lens group 110 and the third lens group 120 increases. This trajectory makes it possible to minimize the storage length of the zoom barrel.

The first lens group 100 includes a first lens 101 and a second lens 102, and the second lens group 110 includes a third lens 111 and a fourth lens of positive, positive, and negative. 112 and a fifth lens 113, and the third lens group 120 includes a sixth lens 121. Reference numeral 131 denotes an infrared filter, and 132 denotes a kava glass. The second lens group 110 may include at least one positive and negative bonding lens. For example, the positive fourth lens 112 and the negative fifth lens 113 may be formed of a bonding lens. have.

The first lens group 100 forms at least one of the lenses having a negative refractive power as an aspherical surface, the second lens group 110 forms at least one of the lenses having a positive refractive power as an aspherical surface and satisfies the following conditional expression It is desirable to.

2.7≤d ₂ /WFno≤3.0

│R ₃₁ │ = │R ₃₂ │

Here, d ₂ is the zoom shift amount of the second lens group, WFno is the F number of the wide-angle end, R ₃₁ is the first radius of the third lens group 120, that is, the radius of curvature of the object side surface, and R ₃₂ is The curvature radius of the last surface of the 3 lens group 120, ie, the image side surface, is shown, respectively.

0.5≤φ _t / φ ₃ ≤1.5

Here, φ _t represents the total refractive index of the telephoto end, and φ ₃ represents the refractive index of the third lens group.

In the trend of miniaturization of the zoom lens system, the use of aspherical surface has several advantages. In particular, when an aspherical surface is used for a lens having a negative refractive power in the first lens group 100, an optical electric field may be reduced in size. It can compensate for aberration and top curvature.

Specifically, the first lens group 100 may include a negative first lens 101 and a positive second lens 102, and the negative first lens 101 may be formed as an aspherical surface. In addition, the second lens group 110 includes a positive first lens 111, a positive second lens 112, and a negative third lens 113. It may be formed as an aspherical surface.

On the other hand, by setting the range of the value obtained by dividing the refractive power of the wide-angle end by the refractive power of the telephoto end as shown in Equation 2, it is possible to configure a three-fold zoom shift optical system in consideration of the nominal value, the first surface of the third lens group 120 By making the curvature of S11 and the last surface S12 the same, a lens can be manufactured using the same base. This reduces the cost of producing additional raw materials, lowers production costs and facilitates assembly production.

On the other hand, the definition of the aspherical surface in the embodiment of the present invention is as follows. The aspherical shape of the compact zoom optical system according to the present invention can be expressed by the following equation with the X-axis as the optical axis direction and the Y-axis as the direction perpendicular to the optical axis direction. Where x is the distance from the vertex of the lens in the optical axis direction, y is the distance in the direction perpendicular to the optical axis, K is the conic constant, A, B, C, D is the aspherical coefficient, c represents the inverse of the radius of curvature (1 / R) at the vertex of the lens, respectively.

The present invention specifically includes lenses according to optimization conditions for implementing miniaturization of the zoom optical system through embodiments according to various designs as follows.

Next, specific lens data of various embodiments of the zoom lens according to the present invention will be described.

<First Embodiment>

EFL is the combined focal length of the whole zoom optics, Fno is the F number, ω is the angle of view, R is the radius of curvature, Dn is the center thickness of the lens or the distance between the lens, and ND is the refractive index, VD represents Abbe's number, respectively. In addition, ST denotes an aperture, and in each embodiment, variable distances between lenses are represented by D ₁ , D ₂ , and D ₃ . In addition, the embodiment number is displayed in association with the reference number of each component for each embodiment.

1 illustrates a zoom lens according to a first embodiment, in which a first lens group 100 includes first and second lenses 101 and 102, and a second lens group 110 includes a third lens. The fourth and fifth lenses 111, 112, and 113 are configured, and the third lens group 120 is configured of the sixth lens 121. Reference numeral 131 denotes an infrared filter, and 132 denotes a kava glass.

EFL: 4.992mm ~ 13.478mm, Fno: 2.829 ~ 4.883, ω: 23.85 ° ~ 61.48 °

Table 2 below shows the aspherical surface coefficients of the first embodiment.

Table 3 below shows examples of the variable distances D1, D2, and D3 according to the first embodiment at the wide-angle end, the intermediate end, and the telephoto end, respectively.

2A and 2B illustrate longitudinal spherical aberration, image curvature, and distortion aberration at a wide-angle end and a telephoto end of a small zoom optical system, respectively, according to an embodiment of the present invention.

Second Embodiment

3 shows the zoom optical system according to the second embodiment at the wide-angle end, the intermediate end and the telephoto end, respectively, and the table below shows the design data thereof.

EFL: 4.622mm ~ 13.035mm, FNO: 2.69 ~ 4.71, Angle of View: 24.61 ° ~ 65.42 °

The following shows the aspherical surface coefficient of the second embodiment.

Table 6 below shows examples of the variable distances D1, D2, and D3 of the zoom optical system according to the third embodiment at the wide-angle end, the intermediate end, and the telephoto end, respectively.

4A and 4B illustrate longitudinal spherical aberration, image curvature, and distortion aberration at the wide-angle end and the telephoto end of the zoom optical system according to the second embodiment, respectively.

Table 7 below indicates that the equations 1 to 2 are satisfied, and the values are as follows.

5 is a cross-sectional view showing a capsule endoscope including a small zoom optical system according to an embodiment of the present invention.

As shown in FIG. 5, the capsule endoscope including the small zoom optical system has a diameter of about 10 mm and a length of about 20 mm, and one end of the housing forming the external shape of the capsule endoscope is formed as a dome-shaped light window 17. The other end is formed of the rectangular housing 18, and forms a bullet shape as a whole.

The light window 17 of the capsule endoscope is made of glass or polycarbonate as a material through which light passes while being harmless to the human body, and the housing 18 is a part including various elements to be described later. As shown in FIG. The light window 17 is sealed with the housing 18 so that, for example, the mucus of the digestive organs or the like is penetrated into the capsule endoscope, or the substance in the capsule endoscope does not leak into the human body.

As shown in FIG. 5, the capsule endoscope has an outer shape formed by a housing made of a light window 17 and a housing 18, and includes an illumination element 12, a lens 13, and an inside of the housing 18. The CMOS image sensor 14 and the battery 15, and the transmission electrode 11 formed electrically isolated from the surface of the housing 18 are included.

First, a lens 13 is disposed behind the light window 17, and a CMOS image sensor 14 in which various circuits are integrated behind the lens 13 is disposed. The distance between the lens 13 and the CMOS image sensor 14 is adjusted so that light incident through the light window 17 can be focused on the surface of the CMOS image sensor 14. A plurality of lighting elements 12 are arranged in a donut-shaped arrangement between the lens 13 and the CMOS image sensor 14. In the embodiment of the present invention, at least four LEDs are used as the lighting element 12. In order to allow the light irradiated from the lighting device 12 to pass through the light window 17 so as to illuminate an object, the inner surface of the light window 17 is non-reflective coding. Behind the CMOS image sensor 14 is a battery 15 which acts as a power source. In the embodiment of the present invention, as the battery 15, a silver oxide battery having a flat discharge voltage and less harm to a human body is used.

The compact zoom optical system according to the present invention has a characteristic that the number of constituent lenses is small, small and thin, and excellent optical performance at a low cost, so as to be suitable for a compact photographing optical system using an imaging device such as a CCD or a CMOS.

The capsule endoscope according to the present invention includes the above-mentioned small zoom optical system in the lens 13. Therefore, the capsule endoscope including the small zoom optical system according to the present invention has a compact zoom function and can obtain a high resolution image in the body cavity of the human body.

Briefly referring to the internal operation of the capsule endoscope, the CMOS image sensor 14 captures an image of an object from the light emitted from the illumination device 12 through the lens 13, and the CMOS image sensor 14 captures the captured image. After the signal is processed through various circuits therein, a signal is applied to a transmission electrode connected to each of the two output lines 16, and as described above, the signal is sensed by a receiving electrode (not shown) outside the human body using the human body as a conductor. do.

The capsule endoscope is a capsule endoscope having at least two electrodes for transmitting biometric information obtained through human body communication using a human body as a medium, and can be driven with low power. In one embodiment of the present invention, since the signal applying line for controlling the illumination unit of the capsule endoscope is provided, it is possible to acquire the body cavity biometric information for a long time.

Although a preferred embodiment of the present invention has been described so far, those skilled in the art will be able to implement in a modified form without departing from the essential characteristics of the present invention.

Therefore, the embodiments of the present invention described herein are to be considered in descriptive sense only and not for purposes of limitation, and the scope of the present invention is shown in the appended claims rather than the foregoing description, and all differences within the equivalent scope of the present invention Should be interpreted as being included in.

Claims (10)

The first lens group has a negative refractive index from the object side, the second lens group has a positive refractive index, and the third lens group has a positive refractive index, and the second lens group is composed of three lenses. Small zoom optical system characterized in that it satisfies. <Conditional expression> 2.7≤d ₂ /WFno≤3.0 0.5≤φ _t / φ ₃ ≤1.5 Here, d ₂ represents the zoom movement amount of the second lens group, WFno represents the F number of the wide-angle end, φ _t represents the total refractive index of the telephoto end, and φ ₃ represents the refractive index of the third lens group, respectively. The method of claim 1, wherein the second lens group, A compact zoom optical system comprising at least one positive and negative bonded lens. The method of claim 1, wherein the second lens group, A compact zoom optical system, characterized by comprising positive, positive, and negative lenses from an object side to an image side. The method of claim 3, wherein the second lens group, Small zoom optical system, characterized in that at least one of the positive lens is composed of an aspherical surface. The method of claim 1, At least one lens of the lenses constituting the first lens group is an aspherical lens. The method of claim 1, At least one lens of the lenses constituting the second lens group is an aspherical lens. An illumination unit for illuminating the living body, an imaging unit for imaging the area illuminated by the illumination unit, an objective optical system positioned in front of the imaging unit, and a transmission unit for transmitting the image information captured by the imaging unit to the outside As a capsule endoscope, The objective optical system uses a compact zoom optical system according to claim 1, characterized in that the capsule endoscope. The method of claim 7, wherein the capsule endoscope, Capsule endoscope further comprises an infrared filter. The method of claim 7, wherein the capsule endoscope, Capsule type endoscope characterized in that using the human body communication to the medium. The method of claim 7, wherein the capsule endoscope, Capsule type endoscope characterized in that using the electric field communication with the electric field as a medium.