KR100814279B1 - Measurement device for alignment of lense assembly - Google Patents

Abstract

A measurement device for alignment of a lens assembly is provided to omit an unnecessary assembly process by measuring the tilting angle of a lens in real time to exclude the inferior lens assembly from the assembly process. A measurement device(100) for alignment of a lens assembly includes a laser beam source(110), two collimation lenses(120,130), an iris(140), a holder(150), a CCD(Charge Coupled Device) lens(160), a CCD(170), and a computer(180). The laser beam source irradiates laser beam to at least one lens in a barrel(10) along the optical axis of the lens assembly. The iris is placed between the two collimation lenses. The holder clamps the barrel. The CCD lens condenses the laser beam passed through the lens. The CCD takes an image of the laser beam condensed by the CCD lens. The computer analyses the image acquired by the CCD.

Description

Measurement Device for Alignment of Lense Assembly

1 is a view showing an example of a compact lens assembly;

2 is a configuration diagram of an alignment measuring device of a small lens assembly according to the present invention; and

3 is a conceptual diagram of a laser image position change according to lens alignment.

<Description of Symbols in Drawings>

10: barrel

20, 30, 40: lens

50: spacer

60: mask

70: shield

100: alignment measuring device of the lens assembly

110: laser light source

120, 130: collimation lens

140: aperture

150: holder

160: CCD lens

170: CCD

180: computer

The present invention relates to a device for measuring alignment of a lens assembly, and more particularly, to an apparatus capable of measuring an angle at which a lens is inclined with respect to an optical axis during a process of assembling a lens assembly of a small optical system such as a lens module of a mobile phone camera. .

In recent years, small electronic devices such as mobile phones and PDAs are increasingly embedded with small cameras. Such a lens module such as a mobile phone camera is composed of a small optical system, so the error in the assembly process of the lens assembly of the lens module is important enough to determine the performance of the camera.

However, during the existing lens assembly assembly process, it is not possible to check the assembly error as to whether the tilting angle of the lens with respect to the optical axis is within an acceptable range. Instead, it is only possible to determine whether the lens module is defective by performing a modulation transfer function (MTF) inspection or analyzing an image photographed by the camera module after assembly of the camera module including the lens assembly is completed. It is not known which part of the assembly is the problem.

This conventional assembly process does not immediately determine whether a defective component is assembled when it is assembled, but determines whether it is defective in the final assembly state, thereby causing unnecessary assembly time and operation of the assembly apparatus and lowering the yield of the product. Let's do it. In addition, it is difficult to find and correct the process that causes the defect.

SUMMARY OF THE INVENTION The present invention has been made from the above-described problems of the conventional small camera assembly process, wherein the laser assembly is irradiated to the lens assembly during assembly and the laser beam is imaged through the lens assembly to measure the tilt angle of each lens in the lens assembly during the assembly process. And it is an object of the present invention to provide a lens assembly alignment measuring device capable of determining whether each of the lenses is defective.

In order to achieve this object, the present invention is a laser light source for irradiating a laser to the lens assembly along the optical axis of the lens assembly; A CCD lens for focusing the laser beam passing through the lens assembly; A CCD for picking up an image of a laser focused by a CCD lens; And calculating means for measuring an angle at which the lens is inclined from the optical axis of the lens assembly based on the image picked up by the CCD.

In order to irradiate the lens assembly with parallel light, the lens assembly alignment measuring device has an aperture between the laser light source and the CCD, two collimating lenses for converting the laser irradiated from the laser light source into parallel light, and an aperture between the two collimating lenses. It may further include a parallel light conversion device.

The determining means may further include determining whether the lens assembly is misaligned based on the angle measured by the calculation means.

The CCD lens and / or CCD may be movable along the optical axis of the lens assembly such that the laser focuses on the CCD surface.

The lens assembly may be a lens assembly used in a lens module for a mobile phone camera.

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

First, the lens assembly to which the present invention is applied will be described.

1 illustrates an example of a lens assembly included in a small camera module such as a camera for a mobile phone.

Referring to FIG. 1, the lens assembly includes a plurality of lenses 20, 30, and 40 inserted into the barrel 10, a spacer 50 and a mask that may be selectively inserted between the lenses 20, 30, and 40. 60), and a shield 70 for protecting the lens assembly from the outside.

The barrel 10 houses the lens assembly.

The plurality of lenses 20, 30, and 40 collect light from a subject to focus on an imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) of a camera module. The shape, number and order of arrangement of the lenses 20, 30 and 40 are selected according to the design purpose.

The spacer 50 may be selectively used when a gap is required between the plurality of lenses 20, 30, 40 according to the design purpose.

The mask 60 may optionally be used where it is necessary to limit light passing through the edge of the lens assembly and to pass light only through the center of the lens assembly, depending on the design purpose.

The shield 70 is used to seal the opening surface of the barrel 10 to fix the lens assembly and to protect it from the outside.

In the lens assembly illustrated in FIG. 1, the lens 20, the spacer 50, the lens 30, the mask 60, the lens 40, and the shield 70 are sequentially inserted into the barrel 10. The assembly is assembled. Each component 20 to 70 inserted into the barrel 10, in particular the lenses 20, 30, 40, must be aligned along the optical axis of the lens assembly. Depending on the tilting angles of the lenses 20, 30, 40 with respect to the optical axis of the lens assembly, the focus by the lens assembly is out of the center of the imaging device, which causes distortion of the image taken by the camera. Therefore, the inclination angle of the lenses 20, 30, 40 should be within a predetermined allowable range.

FIG. 2 shows a configuration of the alignment measuring apparatus 100 of the small lens assembly according to the present invention for measuring the alignment error of the lens assembly as illustrated in FIG. 1.

2, the alignment measuring device 100 of the small lens assembly according to the present invention includes a laser light source 110 for oscillating a laser, between two collimating lenses 120 and 130, and a collimating lens 120 and 130. At the aperture 140, the holder 150 fixing the barrel 10, the CCD lens 160, the charge coupled device (CCD) 170 and the CCD 170. And a computer 180 for analyzing the captured image. The barrel 10 is fixed to the holder 150, and the components 20 to 70 shown in FIG. 1 are inserted in the barrel 10 in the order described above. As an example, the state in which the lens 20 is inserted into the barrel 10 is shown in FIG. 2.

The laser light source 110 oscillates the laser along the optical axis of the lens assembly inserted into the barrel 10. The laser oscillated by the laser light source 110 travels along the optical axis to the lens assembly.

In order to convert the laser oscillated by the laser light source 110 into parallel light, a parallel light conversion device including two collimating lenses 120 and 130 may be installed. In addition, in order to block a laser that can travel in a different direction except for a laser that proceeds in parallel light, the parallel light conversion device may have an aperture 140 between two collimating lenses 120 and 130.

Holder 150 is a device for fixing the barrel (10). The holder 150 allows the central axis of the barrel 10 to exactly match the optical axis of the alignment measuring device 100.

The parallel light laser passing through the parallel light converting devices 120, 130, 140 passes into the barrel 10 fixed by the holder 150, and passes through the lens 20 inserted into the barrel 10.

Lasers that converge or diverge through the lens 20 converge by the CCD lens 160. The focus of the converged laser is located on the surface of CCD 170. That is, the combined focal length of the lens 20 and the CCD lens 160 is equal to the distance from the lens 20 to the CCD 170.

When the focus of the laser is not located on the surface of the CCD 170, the CCD lens 160 moves along the optical axis of the lens assembly, or the CCD 170 moves the optical axis so that the focus of the laser is on the surface of the CCD 170. In addition, the CCD lens 160 and the CCD 170 may move along the optical axis.

The image captured by the CCD 170 is transmitted to the computer 180 for analysis.

Referring to FIG. 3 (the CCD lens 160 has been omitted for convenience of description), the case where the central axis of the lens 20 coincides with the optical axis of the lens assembly, that is, of the lens 20 with respect to the optical axis of the lens assembly. When the tilt angle is 0 °, the focal point of the laser passing through the lens 20 and the CCD lens 160 is on the contact of the optical axis of the lens assembly and the surface of the CCD 170. However, when the tilt angle of the lens 20 with respect to the optical axis of the lens assembly is not 0 ° due to an assembly error (alignment error) when the lens 20 is inserted into the barrel 10 and assembled, the lens 20 and The focus of the laser passing through the CCD lens 160 is out of contact with the optical axis of the lens assembly and the surface of the CCD 170.

The computer 180 analyzes the image measured by the CCD 170 to find the position of the focal point of the laser. The computer 180 calculates the tilt angle of the lens 20 from the found position of the focal point. Then, it is determined whether the inclination angle of the lens 20 is within the tolerance range to determine whether the lens assembly is defective.

Alternatively, the computer 180 calculates in advance the range (A in FIG. 3) where the focus is located when the tilt angle of the lens 20 is within the tolerance range. In addition, the computer 180 analyzes the image measured by the CCD 170 and determines whether the position of the focus of the laser exists in the tolerance range A or outside the tolerance range B. Determine if the assembly is defective.

On the other hand, although the case where the focus of the laser is located on the surface of the CCD 170 has been described, it is also possible that the focus of the laser is not located on the surface of the CCD 170. In this case, the computer 180 analyzes the image picked up by the CCD 170 to calculate the tilt angle of the lens. That is, from the image captured by the CCD 170, the computer 180 selects the center point of the laser on the surface of the CCD 170 by using an algorithm that finds the maximum luminous intensity point, the weighted weighted average point, and the center point of the points having the same luminous intensity. Find. The degree of inclination of the laser passing through the lens 20 and the CCD lens 160 from the center point of the found laser with respect to the optical axis of the lens assembly may be estimated, and the tilt angle of the lens 20 may be calculated.

If the alignment error or tilt angle of the lens assembly is within the allowable range, the process proceeds to the next process for assembling the lens assembly. If the alignment error of the lens assembly is outside the allowable range, the lens assembly is determined to be defective and the assembly process will be stopped.

2 illustrates the case where one lens 20 is inserted into the barrel 10, the lens assembly alignment measuring apparatus 100 according to the present invention also includes the addition of each lens according to the assembly process of the lens assembly. After installation, it is determined whether or not the alignment of the lens assembly.

Since the combined focal length of the lens assembly changes as the lens is added, the curved shape (or focal length) of the CCD lens 160 in each lens assembly alignment measuring apparatus 100 that determines the defect of the lens assembly after each lens insertion. Alternatively, the position, or the position of the CCD 170 may be different.

When the lens is additionally inserted into the barrel, the lens assembly alignment measuring apparatus 100 obtains the combined value of the tilt angle of the additionally inserted lens and the tilt angle of one or more lenses previously inserted as the tilt angle. The computer 180 may calculate the tilt angle of the additionally inserted lens from the difference between the measured value for the one or more previously inserted lenses and the measured value after the additional lens is inserted.

The lens assembly alignment measuring apparatus 100 may determine whether assembly of the lens assembly under assembly is performed when each lens is inserted, and determine which lens among lenses constituting the lens assembly causes assembly failure.

When the lens assembly alignment measuring apparatus 100 according to the present invention is used during a manufacturing process of a small camera such as a mobile phone camera, the assembly state of the lens may be determined by measuring the tilt angle of the lens generated during the assembly of the lens assembly in real time. have. If a defect in the assembly state occurs in real time and by removing the defective lens assembly assembly from the assembly process, unnecessary assembly process can be omitted. In addition, the process of generating a defect can be screened to help fix the problem of the process.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be readily apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention, and all such changes and modifications are It is obvious that it belongs to the scope of the appended claims.

Claims (7)

A lens assembly alignment measuring apparatus for measuring an alignment state of at least one lens of a lens assembly inserted into a barrel, the apparatus comprising: A laser light source for irradiating a laser to at least one lens inserted into the barrel along an optical axis of the lens assembly; A CCD lens for focusing the laser beam that has passed through the at least one lens; A CCD for picking up an image of a laser focused by the CCD lens; And And calculating means for measuring an angle at which the lens is inclined from an optical axis of the lens assembly based on the image picked up by the CCD. The method of claim 1, And a parallel light conversion device positioned between the laser light source and the CCD and having two collimating lenses for converting the laser irradiated from the laser light source into parallel light. The method of claim 2, And said parallel light conversion device further comprises an aperture between said two collimating lenses. The method of claim 1, And determining means for determining whether the lens assembly is misaligned based on the angle measured by the calculating means. The method of claim 1, And the CCD lens is movable along the optical axis of the lens assembly. The method of claim 1, And the CCD is movable along the optical axis of the lens assembly. The method of claim 1, And the lens assembly is a lens assembly used in a lens module for a mobile phone camera.

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