KR20070103553A - Lens having ir cut off filter and manufacturing it's and camera module using it - Google Patents

Abstract

A lens having an IR cut off filter, a manufacturing method thereof, and a camera module using the lens are provided to reduce a module manufacturing cost by minimizing the number of processes and reducing a process error by simplifying the number of components. In a lens having an IR cut off filter, a low-rise thin-film adhesion layer is laminated on one surface of at least plastic lens among a plurality of aspheric plastic lenses(20,21) injection-molded by a polymer-based synthetic resin material and laminated inside a lens barrel(10) and a multi-layered thin-film IR cut off filter layer(22) is formed on a top surface of the low-rise thin-film adhesion layer by the use of a low-temperature deposition method. The low-temperature deposition of the IR cut off filter layer(22) is carried out at a temperature less than 130 degree. A low-temperature deposition condition is in the range of approximately 80 to 130 degree so that a dense thin-film growth of the IR cut off filter layer(22) is available while a temperature of a thin-film layer forming the surface of the aspheric plastic lenses(20,21) maintains a low temperature less than a variation point.

Description

Lens having infrared cut filter integrated lens and manufacturing method thereof and camera module using infrared cut filter integrated lens {Lens having IR cut off filter and manufacturing it's and camera module using it}

1 is a cross-sectional view schematically showing a conventional camera module.

Figure 2 is an exploded perspective view of a substrate portion attached to a conventional camera module.

Figure 3 is a cross-sectional view of the lens barrel equipped with an infrared cut filter integrated lens according to the present invention.

Figure 4 is a graph comparing the transmittance of the aspherical plastic lens according to the present invention,

Figure 4a is a graph of the transmittance of the lens laminated infrared cut filter layer on one surface.

Figure 4b is a graph of the transmittance of the general lens without the infrared cut filter layer.

5 is a comparative photograph of an infrared cut filter layer formed on one surface of a lens according to the present invention;

Figure 5a is a cross-sectional enlarged picture of a typical infrared blocking coating layer.

Figure 5b is an enlarged cross-sectional picture of the infrared cut filter layer formed by the present invention.

<Explanation of symbols for main parts of the drawings>

10. Lens Barrel 20,21 Lens

22. Infrared cut filter layer 23. AR coated surface

The present invention relates to a camera module to which an infrared cut filter integrated lens coated with an infrared cut filter is applied, and more particularly, as the infrared cut filter is deposited at a low temperature in the form of a thin film on one surface of an aspherical plastic lens mounted on the camera module. The present invention relates to an infrared cut filter integrated lens and a camera module using the same, which minimizes the height of the camera module and reduces manufacturing costs by shortening the process by reducing the number of parts.

Nowadays, portable terminals such as mobile phones and PDAs are being used as a multi-convergence with music, movies, TV, and games as well as simple telephone functions with the development of the technology. The camera module is the most representative. The camera module is being changed from the existing 300,000 pixels (VGA level) to the high pixel center of 8 million pixels or more, and is being changed to implement various additional functions such as auto focusing (AF) and optical zoom.

In general, the compact camera module (CCM) is a compact and is applied to various IT devices such as a camera camera, a portable mobile communication device such as a PDA, a smart phone, and a toy camera. The market for mobile devices equipped with small camera modules is increasing according to various consumer tastes.

Such a camera module is manufactured using an image sensor such as a CCD or a CMOS as a main component, and collects an image of an object through the image sensor and stores it as data in a memory in the device, and the stored data is stored in the LCD or PC in the device. It is to be displayed as an image through a display medium such as a monitor.

A typical camera module is typically manufactured by a method such as a chip on board (COB), a chip on flexible (COF), and the like, and a brief structure thereof will be described below with reference to a module assembly diagram of a COF method shown below.

1 is a cross-sectional view schematically showing a conventional camera module, Figure 2 is an exploded perspective view of a substrate portion attached to the conventional camera module.

As shown in the drawing, the conventional camera module 1 has a substrate 7 having a CCD or CMOS image sensor 2 mounted thereon by a flip chip method, and is coupled to a lower portion of the housing 3 made of plastic. 3) The lens barrel 6 with the cylindrical body 5 extending downward is coupled to the barrel 4 extending upward.

The camera module 1 is coupled to the housing 3 and the lens barrel 6 by screwing a female thread formed on the inner circumferential surface of the barrel 4 and a male thread formed on the outer circumferential surface of the cylindrical body 5.

In this case, an infrared cut filter (IR cut) is formed between the upper surface of the substrate 7, that is, the lens L mounted on the lower end of the lens barrel 6 and the image sensor 2 attached to the lower surface of the printed board 7. -off filler (hereinafter referred to as 'IR filter') 8 is combined to block excessive long-wavelength infrared rays entering the image sensor 2.

In the camera module assembled as described above, light flowing from a specific object passes through the lens L, and the image is inverted to focus on the surface of the image sensor 2, where the screw is coupled to the upper end of the housing 3. While the lens barrel 6 is rotated, the adhesive is injected between the housing 3 and the lens barrel 6 at the optimal focus point to bond the housing 3 and the lens barrel 6 in the focused state. By fixing, the final camera module product is produced.

Here, the lens L stacked in multiple stages in the lens barrel 6 functions to form an image on the lower image sensor 2, and the image sensor 2 receives an image from the lens L and receives an image. It produces the color of

The image sensor 2 combines three colors with a color filter of red, green, and blue to generate colors. In the case of red, light having a wavelength longer than a wavelength recognized by a human Because it is recognized by the sensor, the sensor produces a color that is different from the color that humans perceive. Therefore, in order to create a color such as a color recognized by humans, an IR filter for removing stray light included in incident light should be used.

That is, the IR filter is to remove wavelengths in the near infrared region from the light incident through the plurality of lens groups, and an image sensor made of a CCD or a CMOS is used to convert a light signal into an electrical signal to form an image. In addition to the visible visible region (400-700nm) as well as the near-infrared region (~ 1150 nm), the signal irrelevant to the actual color or image saturates the detector, so as to remove wavelengths in the near-infrared region. Two materials with different refractive indexes (TiO ₂ / SiO ₂ or Ta ₂ O ₅ / SiO ₂ ) are alternately deposited on a glass substrate to transmit 30 to 40 layers, which transmits visible region and reflects near-infrared region of 750 nm or more. It consists of a filter.

As described above, when manufacturing a camera module such as a COF, COB, or CSP method according to the mounting position of the image sensor, a long wavelength infrared ray is cut off and a sensing surface of the image sensor is commonly cut on the optical path flowing into the light receiving unit of the image sensor. A bonding process using a UV curable adhesive for fixing the IR filter in the form of a transparent glass to block external moisture is commonly performed.

On the other hand, in recent years, as the resolution or number of pixels required by consumers increases and the camera module mounted on a mobile communication terminal including a mobile phone is miniaturized, an IR filter is not used separately and the glass 8 mounted inside the housing is not used. By forming an IR coating film that functions as an IR filter, or by forming an IR coating film on one surface of a plurality of glass lenses mounted in the lens barrel, a camera module having a space reduced by the thickness of the IR filter is manufactured.

However, when the glass with the IR coating film is formed as described above, or when the glass lens L having the IR coating film is used, the glass module made of glass or plastic must be separately mounted on the upper surface of the substrate on which the image sensor is attached. There is a limit in reducing the size of ie, the height from the substrate to the top of the lens barrel 6.

In addition, since the glass having the same size or smaller size as the substrate 7 should always be mounted, the supply cost of the glass and the process of attaching the glass on which the IR coating film is formed must be added, thereby increasing the manufacturing cost of the camera module. The problem is pointed out.

Therefore, the present invention was devised to solve the above-mentioned disadvantages and problems in the conventional camera module, and a plurality of aspherical plastic lenses are laminated and combined in the lens barrel of the camera module, and at least one aspherical plastic lens is infrared Since the optical filter layer for blocking the thin film is densely deposited by low temperature deposition method, the infrared filter filter integrated lens is provided to remove the glass-type IR filter in the camera module to minimize the height of the camera module. There is a purpose.

In addition, another object of the present invention is to reduce the number of parts according to the manufacturing of the camera module using a lens formed integrally with the IR filter layer on one surface, by eliminating the labor for fixing and fixing the IR filter when manufacturing the module, the manufacturing cost of the module product This saving camera module is provided.

The object of the present invention is a camera module in which the housing and the lens barrel is screwed perpendicularly to the optical axis, the lens barrel is mounted with at least one aspherical plastic lens formed with an infrared cut thin film layer on one surface, the lens barrel is an upper end And a printed circuit board including a housing coupled to the center, and an image sensor mounted at a central portion by a wire or flip chip, and a lower end portion of the housing closely coupled to the edge portion thereof.

In the lens barrel, one or more lenses are sequentially coupled therein, and the lenses are composed of only aspherical plastic lenses or are laminated and combined in a state in which an aspherical plastic lens and a glass lens are mixed. In this case, one surface of any one of the aspherical plastic lenses of the plurality of aspherical plastic lenses is coated with an infrared cut filter layer in the form of a multi-layer thin film, thereby blocking the infrared transmission of the long wavelength included in the incident light passing through the lens.

In addition, the aspherical plastic lens is manufactured by injection molding using a polymer-based synthetic resin material, and the infrared blocking filter layer forming a thin film layer on one surface of the aspherical plastic lens is a low temperature by an ion beam in which a plasma source is used as an assistant. It is coated by a vapor deposition method.

At this time, the deposition temperature of the infrared cut filter layer is determined at a temperature between a minimum of 80 ℃ and a maximum of 130 ℃.

The infrared cut filter layer is an adhesive layer layer in which CeO ₂ / SiO ₂ is deposited to a thickness of several nm in order to improve adhesion between one surface of an aspherical plastic lens and the optical filter layer before a plurality of optical filter layers for blocking infrared rays are deposited. By first forming, the compressive stress due to the curvature of the deposition lens is relaxed.

Meanwhile, the thin film layer deposited on the adhesive layer layer formed on one surface of the aspherical plastic lens is deposited at low temperature while alternately stacking the high refractive layer and the low refractive layer, and the lamination thickness satisfies the following equation.

Where n _L is the refractive index value of the layer deposited on the lens surface,

d _L : thickness of the layer deposited on the lens surface

n _N : refractive index of the Nth layer,

d _N : thickness of the Nth layer,

n _A : Refractive index value of the layer deposited on the outermost layer.

d _A : thickness of the layer deposited on the outermost layer.

In the camera module of the present invention configured as described above, the infrared rays of the long wavelength band included in the incident light collected by the image sensor in the module pass through a plurality of lenses stacked in the lens barrel, and are formed by depositing a multilayer thin film on any one surface of the lenses. By blocking through the blocking filter layer, as the camera module is assembled without a separate infrared blocking filter, the ultra-thin camera module can be achieved and the infrared blocking filter layer is formed on one of the lenses of one of the plurality of lenses. As the deposition is formed, the gap between the image sensor and the blocking filter layer is relatively far, and thus there is a technical characteristic that the foreign material defect may be improved.

In addition, the present invention is a low-temperature deposition method using an ion beam containing a plasma source by depositing a multi-layer thin film filter layer on the aspherical plastic lens surface, within a temperature range that does not affect the crystal structure of the plastic lens of the polymer (polymer) material Another technical feature is to allow dense thin film growth of the thin film filter layer.

Details of the effects, including the technical configuration for the above object of the infrared cut filter integrated lens and the camera module using the same of the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention. .

First, Figure 3 is a cross-sectional view of the lens barrel equipped with an infrared cut filter integrated lens according to the present invention.

As shown, the lens barrel 10 is laminated at least one or more aspherical lens 20 is sequentially laminated, one aspherical lens 21 of the lens 20 is laminated in a plurality of thin film form on one surface An infrared cut filter layer 22 is formed.

In addition, the plurality of lenses 20 and 21 stacked in the lens barrel 10 may be composed of an aspherical plastic lens 21 and a glass lens that are injection molded in a polymer series, or both aspherical surfaces. It can be laminated and bonded only with the plastic lens, the infrared cut filter layer 22 is deposited on any one surface of the aspherical plastic lens 21.

The infrared cut filter layer 22 is formed on the one surface of the aspherical plastic lens 21 by low temperature deposition by an ion beam by the help of a plasma source, and the infrared cut filter layer 22 ) Is carried out at a temperature of 130 ° C. or less, which is a temperature below the transition point of the aspherical plastic lens 21. At this time, the low temperature deposition temperature condition for allowing the thin film growth of the infrared cut filter layer 22 to be possible while maintaining the low temperature of the thin film layer forming surface of the aspherical plastic lens 21 is below the transition point is approximately 80 ~ 130 ℃. It is preferred to remain in between.

Here, the specific forming conditions and the process of the infrared cut filter layer 22 forming a thin film layer on one surface of the aspherical plastic lens 21 will be described as follows.

The infrared cut filter layer 22 is formed of a thin film layer having a total of about 40 layers in which a low refractive index layer and a high refractive layer forming a multilayer optical thin film layer form a 4 to 5㎛. In this case, the infrared blocking filter layer 22 may weaken the adhesive force between the thin film layer and the lens surface due to stress generated between the plastic lens 21 surface and the dielectric thin film, thereby causing de-lamination of the thin film. In order to minimize this, five layers are first deposited on one surface of the aspherical plastic lens 21 to form a thin film adhesive layer of several nm.

The thin film adhesive layer is formed by the deposition using CeO ₂ / SiO ₂ , the thin film layer formed on the aspherical surface of the lens 21 by relieving the compressive stress generated according to the degree of curvature of the thin film due to the curvature of the aspherical plastic lens 21 To enhance the adhesion of the resin.

The infrared cut filter layer 22 deposited on the aspherical surface of the plastic lens 21 with the thin film adhesive layer interposed therebetween is deposited by alternately stacking a high refractive index component and a high refractive index component. ₂ , TaO ₂ , ZrO ₂ , Ta ₂ O ₅ , and the like, and representative materials exhibiting low refractive index include SiO ₂ and Al ₂ O ₃ .

In the alternate deposition of the high refractive index layer and the low refractive index layer, the aspherical plastic lens 21 is mounted inside the dome-shaped chamber, and then the inside of the chamber is maintained in a vacuum state by a pump for 30 minutes and at the same time, the plastic lens is used. The temperature of the thin film deposition surface of (21) is maintained between 80 ~ 130 ℃, at this time by operating a cryo pump (cryo pump) to maintain the air pressure finely adjusted to the deposition air pressure of 1 × 10 ^-6 Torr The deposition time of one cycle was limited to 5 hours.

Herein, the infrared cut filter layer 22 deposited on one surface of the aspherical plastic lens 21 is formed to have a thickness of about 4 to 5 μm of about 40 layers, and a growth rate of the thickness is 0.5 to 1.5. As it is maintained at ㎚ / sec, the wavelength (wavelength) blocked through the infrared cut filter layer 22 laminated on one surface of the aspherical plastic lens 21 is determined within about 645 ± 5nm.

In addition, the infrared cut filter layer 22 should find an optimal thin film coating surface on the aspherical surface of the aspherical plastic lens 21 so that the optical coating of the multilayer thin film can be performed. Of the lens surface having the portion to be minimized and the rotationally symmetric optical surface, only a portion having a small curvature R, that is, a curved surface that can include all incident light, is determined as an optimal coating surface.

In this case, when the multilayer thin film of the infrared cut filter layer 22 is formed, the incident angle of the light ray to the lens surface on which the thin film layer is formed due to multiple interferences increases, thereby reducing the infrared ray blocking effect, and the uniformity of the individual thin film layers of the lens coating surface. Since the curvature is controlled, the thin film should be formed in consideration of the change in the wavelength band of the infrared cut-off when the thickness changes due to the growth of the number of layers of the multilayer thin film.

In addition, since the brightness on the axis of the plastic lens 21 with respect to one point on the aspherical surface is reduced with a cosine quadratic, it should be designed in consideration of the amount of brightness reduction around the lens, and the design condition is satisfied by the following equation. do.

Meanwhile, an AR coating surface 23, which is an antireflective coating, is formed on the other side of the aspherical plastic lens 21 having the multilayered infrared cut filter layer 22 deposited on one surface thereof, and the AR coating surface 23 is a lens 21. By efficiently absorbing and passing the light passing through), the light efficiency is increased, and the phenomena generated by the incident light passing through the aspherical lens are reduced.

Next, Figure 4 is a graph comparing the transmittance of the aspherical plastic lens according to the present invention, Figure 4a is a graph of the transmittance of the lens with an infrared cut filter layer laminated on one surface, Figure 4b is a graph of the transmittance of a general lens without the infrared cut filter layer to be.

As shown in the figure, in the case of a general lens having no infrared cutoff filter layer laminated according to the present invention, as shown in FIG. 4B, a high transmittance of 90% or more is exhibited in almost all wavelength bands. The aspherical plastic lens 21 in which the infrared cut filter layer 22 is laminated is transmitted at least 89% of the infrared rays in the visible light region of 400 to 600 nm, and the front and rear surfaces of the lens 21 before and after the 650 nm infrared cut-off wavelength band. As the inflow of infrared rays is drastically reduced, it can be seen that only infrared rays within 5% are transmitted at or above 650 nm.

Accordingly, as the infrared transmittance of the general lens without the infrared cut filter layer 22 is measured at 95% in the wavelength band of 650 nm or more, the infrared transmittance cutoff of the infrared cut filter layer 22 by the low temperature deposition using the same is 93% or more. Can be expected.

Finally, Figure 5 is a comparison picture of the infrared cut filter layer formed on one surface of the lens according to the present invention, Figure 5a is a cross-sectional enlarged picture of the general infrared cut coating layer, Figure 5b is a cross-sectional enlarged picture of the infrared cut filter layer formed by the present invention. to be.

As shown in FIG. 5A, in which a coating surface is formed by a general deposition method, the adhesive layer of each thin film layer is not hard, and each thin film layer is formed in a lattice structure of columns, thereby significantly reducing transmittance. The infrared cut filter layer 22 formed by the low temperature deposition using the plasma of FIG. 5B may have good transmittance as the thin film layers are densely attached and each thin film layer is formed in an amorphous structure without empty space. .

Preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications, and changes within the scope without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It will be possible, but such substitutions, changes and the like should be regarded as belonging to the following claims.

As described above, the infrared cut filter integrated lens of the present invention and the camera module using the same are formed by stacking at least one aspherical plastic lens in which an infrared cut filter layer for blocking infrared rays in the lens barrel of the camera module is laminated. As the camera module is assembled without a separate IR filter, a thinner camera module product can be expected to reduce the module height by at least 0.2 mm.

In addition, the present invention has a merit that the manufacturing process is reduced by eliminating the bonding process and the adhesive curing process for fixing the separate IR filter, and the module manufacturing cost by the reduction of the labor cost can be reduced and the number of parts is simplified by The effect is that the process defects can be significantly reduced.

Claims (10)

A low-layer thin film adhesive layer is formed on one surface of at least one plastic lens among a plurality of aspherical plastic lenses that are injection-molded with a polymer-based synthetic resin material and mixed or laminated with a glass lens alone in a lens barrel. An infrared cut filter integrated lens for forming an infrared cut filter layer of a multilayer thin film by vapor deposition. The method of claim 1, The thin film adhesive layer is an infrared cut filter integrated lens, characterized in that deposited on the aspheric plastic lens surface in about five layers using CeO ₂ / SiO ₂ . The method of claim 1, The infrared cut filter layer is an infrared cut filter-integrated lens, characterized in that formed on the curved surface of the small curvature portion of the aspherical lens surface having a portion of the incident angle and the rotationally symmetric optical surface by the paraxial ray tracing . The method according to claim 1 or 3, The infrared cut filter layer, the brightness on the non-axis relative to the point extracted from the curved portion of the aspherical surface should be designed in consideration of the amount of brightness reduction around the lens, the design conditions,

Infrared cut filter integrated lens, characterized in that to satisfy the equation. The method of claim 1, The aspherical plastic lens, the infrared cut filter integrated lens, characterized in that the infrared cut filter layer of the multi-layer thin film is formed on the other side of the deposition surface AR coating surface is an antireflective coating. Mounting an aspherical plastic lens in the chamber; Converting the interior of the chamber into an initial vacuum over 30 minutes; Operating a cryo pump for high vacuum inside the chamber; Stabilizing the vacuum in the chamber by lowering the pressure in the chamber to 1 × 10 ⁻⁶ Torr; Alternately low temperature deposition of infrared cut filter layers on one surface of the aspherical plastic lens; Method of manufacturing an infrared cut filter integrated lens comprising a. The method of claim 6, Before the step of depositing the infrared cut filter layer, the method of manufacturing an infrared cut filter integrated lens, characterized in that further comprising the step of laminating a thin film adhesive layer by using an ion beam by the aid of a plasma source. The method of claim 6, In the step of depositing the infrared cut filter layer, the low temperature deposition temperature conditions for dense thin film growth of the infrared cut filter layer is maintained between 80 ~ 130 ℃ manufacturing method of the infrared cut filter integrated lens. In the camera module, the housing and the lens barrel is screwed perpendicularly to the optical axis, An infrared cut filter integrated lens according to any one of claims 1 to 7; A lens barrel having a cylindrical body in which a plurality of lenses including at least one lens including the infrared cut filter integrated body are sequentially stacked and coupled to the bottom; A housing in which a barrel through which the cylindrical body of the lens barrel is rotatably coupled extends upward; And A printed circuit board on which a lower end of the housing is tightly coupled, and an image sensor mounted on the central portion thereof is covered by the housing; Camera module comprising a. The method of claim 9, The infrared cut filter integrated lens, the camera module, characterized in that can be applied to all of the manufacturing method (Chip On Flexible), COB (Chip On Board), COG (Chip On Glass) and CSP (Chip Size Package).

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