KR101436932B1 - Fault diagnostic method and devices - Google Patents

Abstract

The present invention relates to a fault diagnosis device and a fault diagnosis method of an automatic focusing module and, more specifically, to a fault diagnosis device and a fault diagnosis method of an automatic focusing module which can test driving performance in accordance with the change in current, determine a failure through the analysis of natural frequency characteristics, and determine failure causes such as contamination failure and poor bonding failure.

Description

{Fault diagnostic method and devices}

The present invention relates to a defect diagnosis method and an apparatus for diagnosing a defect in an autofocus module, and more particularly, it relates to a drive performance test according to a change in current, The present invention relates to a defect diagnosis method and an apparatus for diagnosing a defect of an auto focus module,

In general, a lens assembly mounted on a mobile phone, a PDA, a digital camera, or the like requires a high-resolution high-resolution camera, and such a device requires a device that automatically focuses the image. Particularly, in order to automatically focus the image, a lens actuator capable of linearly moving the lens module is required.

Such lens actuators are classified into three types, namely, a rotary motor type, a PZT (Piezo Actuators) type, and a VCM (Voice Coil Motor) type.

In the rotation motor system, a step motor or a DC motor is used as a structure for changing the rotation motion to a straight line. However, since it is difficult to miniaturize the focus adjustment device, it is not easy to apply to a small lens module such as a camera phone .

In addition, the PZT method can be made small in size and light in weight, but has a disadvantage in that a high-voltage power source is required.

To solve this problem, the VCM method was applied. The VCM method utilizes the electromagnetic force generated between the magnetic fluxes of the coil and the magnet through which current flows, and there is no backlash generated when the gear is used because the reduction gear is not used. In addition, since the VCM system does not use gears, noise is not generated.

Such a conventional VCM-type lens actuator is mounted on a carrier to which the lens module is fixed, as disclosed in Korean Patent Laid-Open Publication No. 2008-0010861 (published on January 31, 2008, entitled: And a structure in which a plurality of permanent magnets are arranged around the coil. At this time, when a current is applied to the coil, the carrier is linearly moved in the forward / backward direction by an electromagnetic force generated between the magnetic fluxes of the coil and the permanent magnet, thereby performing focus adjustment operation.

As performance becomes higher, VCM is demanding more stringent standards for good performance. Most of the defects in the VCM equipped with the AF function are judged mainly by prediction of the leaf spring deformation of the VCM due to the drop impact test, which has a limitation in that it can determine only defects of some parts.

In addition, it is very important to identify the cause of defects in the production site even when defects occur.

In addition, since the VCM is assembled and bonded with complicated ultra-thin parts, there is a problem that it is very difficult to grasp the cause of defects through decomposition.

Therefore, it is necessary to develop a technology that can meet the strict performance evaluation criteria according to the high performance of VCM.

Korean Patent Laid-Open Publication No. 2008-0010861 (published on January 31, 2008, entitled "Automatic focusing device of lens module")

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a driving performance test according to current change, And to provide a defect diagnosis method and a defect diagnosis apparatus of an autofocus module that can satisfy the performance evaluation criterion stricter with high performance and greatly improve the reliability by identifying the same defect cause.

According to an embodiment of the present invention, there is provided a method of diagnosing defects in an autofocus module, comprising the steps of: a) fixing an autofocus module to a fixing jig and adjusting an initial position; b) powering said autofocus module by signal supply means; c) supplying a current signal having a predetermined frequency to the autofocus module by the signal supply means; d) analyzing natural frequency characteristics from the autofocus module measurement signal synchronized with the current signal; e) analyzing Fast Fourier Transform (FFT) characteristics of the autofocus module; f) comparing the analysis result of the measured auto focus module with the analysis result of the existing good auto focus module to judge the failure; And a control unit.

In addition, the method for diagnosing defects of an autofocus module according to an embodiment of the present invention may further include the steps of: g) after the step b), the current supplied to the autofocus module by the signal supply means is stepwise raised or lowered ; h) measuring a displacement of the autofocus module according to a driving current by a displacement sensor mounted on the upper side of the autofocus module; . ≪ / RTI >

Also, in the step f) according to the embodiment of the present invention, when the displacement of the autofocus module according to the driving current is measured in the step h) and a specific section hysteresis is generated in the created graph, The cause of the failure can be estimated.

Also, in step d) according to an embodiment of the present invention, after offset and displacement are set, a current signal having a predetermined frequency is applied to spectrum analysis, and a magnitude response to the frequency of the sine signal can be represented by a table.

Also, in step e) according to an embodiment of the present invention, when the autofocus module is a good product, a harmonic peak may be detected at a frequency that is an integer multiple of the excitation frequency.

Also, in step f) according to an embodiment of the present invention, the magnitude response peak of the Bode diagram appears as a multi-peak at a higher frequency than that of a good product through the spectrum analysis result of step d) It is possible to determine that some parts of the autofocus module are defective when the subharmonic is detected.

In addition, the apparatus for diagnosing defects of an autofocus module according to an embodiment of the present invention includes: a fixing jig to which an autofocus module is fixed; A laser displacement sensor mounted on the fixing jig for measuring a displacement of the autofocus module; A sensor processing unit for controlling the displacement sensor and processing data obtained from the displacement sensor; A position adjusting stage for adjusting a position of the displacement sensor; Signal supplying means for supplying a power source for driving the autofocus module or supplying a sine signal, which is a sinusoidal current having a predetermined frequency; High speed photographing means driven by the signal supply means for photographing the motion of the operating autofocus module and generating a profile through the photographed image; And is characterized in that it comprises:

Further, the signal supply means according to an embodiment of the present invention includes a power supply for supplying power; And dynamic signal analyzers capable of generating power and sinusoidal currents; As shown in FIG.

The defect diagnosis method and the defect diagnosis apparatus of the VCM module for mobile according to the present invention not only determine whether the auto focus module is defective by the driving performance test according to the current change, And can identify the cause of defects such as defective bonding and poor bonding. In addition, it has been experimentally verified that it is possible to detect a defect in a module which has been misjudged as a good product because it can not be detected by a conventional driving performance test even though it is an actual defective product.

The conventional driving performance test which judged the defectiveness by comparing the displacement of the autofocus module according to the current change and comparing it with good products has a problem that it can judge only whether it is positive or negative, It is difficult to determine the cause of failure due to disassembly. Further, even in the case of a connection failure in which a part of the auto-focus module component is not bonded, it is sometimes judged as a good product as a result of the existing driving performance test.

However, according to the present invention, an autofocus module having a faulty foreign matter incorporation characteristic by analyzing the inherent frequency characteristic and the vibration characteristic analysis through the existing driving performance test, the magnitude response peak of the Bode diagram created by analyzing the natural frequency characteristic appears in a relatively high frequency range In addition, hysteresis occurs in some sections in the conventional driving performance test, and the autofocus module having a defective junction is judged to be a good product in the conventional driving performance test results. However, when the Bode line size response peak is higher than the good product It is possible to estimate the cause of the defect even if the auto focus module is not disassembled or destroyed by using the characteristic that the harmonic peak of the auto focus module is detected in an interval which is not an integral multiple in the FFT characteristic analysis. There is an advantage that judgment can be made.

In addition, according to the present invention, the magnitude response peak of the Bode diagram created by analyzing the natural frequency characteristics of the autofocus module may be judged to be defective through the characteristic that unstable fluctuation appears at the high frequency end portion.

Accordingly, the present invention can meet the stringent performance evaluation criteria according to the high performance of the mobile device to which the autofocus module is applied, and the reliability can be greatly improved through accurate defect determination and defect cause estimation.

1 is a schematic diagram showing a defect diagnosis apparatus for an autofocus module according to the present invention;
2 and 3 are a cross-sectional view and a perspective view of a general mobile VCM module.
4 is a graph showing an analysis of a good-quality auto focus module through step d) of the defect diagnosis method of the autofocus module according to the present invention.
5 is a graph showing an analysis of a good product autofocus module through step e) of the defect diagnosis method of the autofocus module according to the present invention.
FIG. 6 is a graph showing an analysis of a good-quality auto focus module through step h) of the defect diagnosis method of the autofocus module according to the present invention.
FIG. 7 is a graph showing an analysis of an autofocus module having foreign matter mixing failure through step h) of the defect diagnosis method of the autofocus module according to the present invention. FIG.
FIG. 8 is a graph showing an analysis of an autofocus module having a defective junction through step h) of the defect diagnosis method of the autofocus module according to the present invention.
FIG. 9 is a graph showing an analysis of an autofocus module having a defective junction through step d) of the defect diagnosis method of the autofocus module according to the present invention. FIG.
FIG. 10 is a graph showing an analysis of an autofocus module having a defective junction through step (e) of the defect diagnosis method of the autofocus module according to the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a defect diagnosis method and a defect diagnosis apparatus of an autofocus module according to the present invention will be described in detail with reference to the accompanying drawings.

Example 1.

In the first embodiment, the defect diagnosis apparatus 1 of the autofocus module according to the present invention will be described with reference to Figs. 1 to 3. Fig.

The defect diagnosis apparatus 1 of the autofocus module of the present invention mainly includes a fixing jig 100, a laser displacement sensor 200, a sensor processing unit 300, a position adjustment stage 330, a signal supply unit 400, And a photographing means (500).

Here, the autofocus module may be a VCM for mobile, a type having a Hall sensor mounted on the VCM as an encoder type, and various modifications can be made in the auto focus module.

However, for convenience of explanation, the following description will be made with reference to a mobile VCM module.

First, a brief configuration of the autofocus module 10 will be described. In the autofocus module 10, the focus adjusting device is configured such that the cover 11 and the holder 12 are coupled to each other to form a space, A plurality of permanent magnets 15 constituting a magnetic circuit are mounted through an inner yoke 13 and an outer yoke 14 and an inner circumferential surface of the permanent magnet 15 is fitted with a lens module The upper and lower springs 18 and 19 to which an external power source is input are coupled to the carrier 17 while the carrier 17 is fastened to the holder 12 and the cover 11, .

The upper spring 18 functions to return the carrier 17 when the power of the coil 16 is released.

When a current is supplied to the coil 16 to operate the autofocus module 10, the carrier 17 coupled with the coil 16 by the interaction of the coil 16 and the permanent magnet 15 is a straight line The lens protrudes to the outside of the cover 11 because of the movement.

The autofocus module 10 is not necessarily limited to the configuration described above, and it is possible to change or delete some of the configurations as necessary.

Preferably, the fixing jig 100 is detachably fixed to the autofocus module 10, and the jig 100 can be easily changed according to a model change.

The displacement sensor 200 is mounted on the fixing jig 100 to measure the displacement of the autofocus module 10 and may be a laser displacement sensor or a capacitive displacement sensor.

The displacement sensor 200 irradiates a laser to the autofocus module 10 fixed to the fixing jig 100 to measure the movement distance of the carrier.

The sensor processing unit 300 may include a control unit 310 for controlling the displacement sensor 200 and a DAQ system 320 for acquiring and processing the displacement sensor 200.

The position adjustment stage 330 adjusts the position of the displacement sensor 200 so that the irradiated laser can be irradiated to the focal position of the autofocus module 10. [

The signal supply unit 400 supplies power for driving the autofocus module 10 or supplies a sine signal, which is a sinusoidal current having a predetermined frequency.

The signal supply means 400 may be a power supply 410 capable of simply changing the current supplied to the autofocus module 10 when measuring the displacement of the autofocus module 10 according to the current change A dynamic signal analyzer 420 may be used to supply a sinusoidal signal of a sinusoidal waveform having a predetermined frequency to the autofocus module 10 in order to measure a natural frequency characteristic.

As described above, the signal supply means 400 may be a power supply 410 and a dynamic signal analyzer 420, but may be a function generator for generating a current having a predetermined frequency, A generator, and an amplifier (amp).

The high-speed photographing means 500 may be a high-speed camera capable of photographing the motion of the autofocus module 10 driven by the signal supply means 400 and generating a profile through the photographed image have.

The high-speed camera can be a model capable of high-speed measurement of 2,000 fps @ 1016 x 1016 pixels up to 26,000 fps @ 1010 x 64 pixels.

Accordingly, since the defect diagnosis apparatus 1 for a mobile autofocus module 10 of the present invention is provided with only the dynamic signal analyzer 420 and the high speed photographing means 500 in the existing experimental apparatus for performance testing, It is possible to diagnose faults without the need to produce equipment, and it can be easily applied in the industrial field.

Example 2.

In Embodiment 2, a defect diagnosis method of the autofocus module according to the present invention will be described with reference to FIGS. 4 to 10. FIG.

Particularly, in the second embodiment, a method of judging the defective junction will be described.

In the defect diagnosis method of the autofocus module according to the present invention, the autofocus module 10 having the foreign substance incorporation defect through the existing drive performance test and the natural frequency characteristic analysis analyzes the characteristic frequency characteristic of the Bode- The hysteresis occurs in some sections in the conventional driving performance test and the autofocus module 10 having the defective connection is judged to be good in the result of the driving performance test in the past, Using the characteristic that the magnitude response peak appears in the form of a multi-peak at a higher frequency than that of a good product, and the harmonic peak of the autofocus module 10 is detected in an interval that is not an integral multiple in the FFT characteristic analysis, Even if it is not decomposed or destroyed, the cause of the defect can be estimated and accurate defect determination is possible.

The method of diagnosing defects of an autofocus module according to the present invention comprises the steps of: a) fixing an autofocus module (10) to a fixing jig (100) and adjusting an initial position; b) powering the autofocus module (10) by the signal supply means (400); c) supplying a current signal having a predetermined frequency, that is, a current signal having a predetermined frequency such as a sinusoidal wave or a square wave, to the autofocus module 10 in the signal supply means 400; d) analyzing natural frequency characteristics by obtaining a Bode plot from a measurement signal of the autofocus module (10) synchronized with a current signal; e) analyzing the characteristic of the autofocus module 10 and the FFT characteristic corresponding to self-excitation; f) comparing an analysis result of the measured auto focus module 10 and an analysis result of the previously-measured good auto focus module 10 to determine a failure; .

In addition, the defect diagnosis method of the autofocus module of the present invention may include a step of g) a step of g) a step of raising or lowering the current supplied to the autofocus module 10 by a predetermined unit by the signal supply means 400 ; h) measuring a displacement of the VCM according to a driving current by a displacement sensor mounted on the autofocus module (10); May be carried out after the step b).

The steps g) and h) may be carried out before the step c), or between the steps e) and f).

Since the VCM module is an open loop position control, it is important to ensure position reproducibility corresponding to the applied current. The main performance test items of the VCM are startup current, maximum displacement, hysteresis, and the like. The starting current represents a current value at the time when a predetermined initial displacement occurs, and the maximum displacement represents the maximum amount of movement of the carrier 17 in the autofocus module 10 when the maximum applied current is added.

In order to perform the performance test, the current is gradually increased from 0 to a predetermined value, and then the current is decreased again. The hysteresis is evaluated by the difference between the rising and falling positions.

It is preferable that the defect diagnosis method of the autofocus module of the present invention is performed in a clean room in order to prevent defects caused by contamination of foreign objects during inspection.

The main specifications of the autofocus module 10 prepared for verifying the defect diagnosis method of the autofocus module of the present invention are as follows.

Test condition Specification Peak stroke @ 90 mA ≤ 0.2 mm Starting current Current @ 10 μm driven position 16 ~ 37mA Sensitivity Stroke / current @ 40 ~ 60mA 3.6 to 9 μm / mA Hysteresis 0mA → 90mA → 0mA ≥ 10 μm

First, FIG. 6 shows a result of inspection of a good module through an existing performance test for comparison with a bad module.

As shown in FIG. 6, the good product module satisfies all of the specifications shown in Table 1 as a result of the performance test, and it can be seen that no hysteresis occurs.

FIG. 4 is a graph showing the analysis of the good product autofocus module 10 through the step d) of the defect diagnosis method of the autofocus module according to the present invention.

To this end, in the defect diagnosis method of the autofocus module according to the present invention, when the signal supply means 400 is formed including the power supply 410 and the dynamic signal analyzer 420, an offset of 800 mV and a sweep sine signal was applied after setting the offset of 200 mV and performing a spectrum analysis.

At this time, the generated Bode diagram is a table showing the magnitude response (dB) with respect to the frequency of the sine signal by performing spectrum analysis by applying a sine signal after offset and displacement setting as described above.

4 is a graph prepared by superimposing three times repeated measurement results on a spectrum analysis graph of a good product module. As shown in FIG. 4, it can be seen that the good module has a natural frequency near about 60 Hz.

FIG. 5 is a graph showing an analysis of the good autofocus module 10 through e) of the defect diagnosis method of the autofocus module according to the present invention. FIG. 5 is a graph showing the results of Fast Fourier Transform (FFT) analysis .

As shown in FIG. 5, a harmonic peak was detected at a point where the good module was excited with a natural frequency of 60 Hz, where it was an integer multiple of the exciting frequency.

Next, the defective module having the defective connection was inspected by the defect diagnosis method of the autofocus module according to the present invention. Particularly, the bonding failure module used for verifying the defect diagnosis method of the autofocus module of the present invention is a module in which a part of the upper spring 18 is not bonded.

In the conventional driving performance test, that is, in the result of steps g) and h), the module in which the partial area of the upper spring 18 is not bonded is very similar to the good module as shown in Fig. 8, The present invention is suitable for verifying a defect diagnosis method of an autofocus module according to the present invention because it can cause a tilt during driving when used in an actual mobile phone and thus cause image degradation.

FIG. 9 is a graph showing a spectral analysis of the autofocus module 10 having a defective connection through step d) of the defect diagnosis method of the autofocus module according to the present invention. As a result of the analysis, the overall tendency is similar, It can be seen that natural frequencies occur at about 95-97 Hz, which is the frequency.

Further, in FIG. 4, it is confirmed that the joining defective module generates multi-peaks and shifts the natural frequency in the high-frequency region, compared with a case where a single peak of the good module is generated smoothly.

In addition, when the coupling failure module is excited at a frequency of 90 Hz, which is the natural frequency region obtained through the step d), a sub-harmonic component is generated even in a region that is not an integral multiple such as 0.5, 1.5, appear.

As a result, even if the defect diagnosis method of the autofocus module according to the present invention is judged to be good in the driving performance test through steps g) and h), the spectral analysis result of step d) When the harmonic peak of the autofocus module 10 is detected in an interval that is not an integral multiple through the result of the FFT characteristic analysis of the step e) It is determined that some of the components of the semiconductor device 10 are defective in bonding.

Example 3.

In Embodiment 3, a method of determining foreign matter mixing failure through the defect diagnosis method of the autofocus module according to the present invention will be described.

The driving performance test and natural frequency characteristics are analyzed with the foreign matter misfit module manufactured to verify the defect diagnosis method of the autofocus module according to the present invention.

At this time, the foreign matter misfit module was manufactured by inserting a ball between the lower spring of the good module and the coil 16.

First, for the performance test, hysteresis is evaluated by the position difference between rising and falling by performing the operation of increasing the current from 0 to a predetermined value step by step and decreasing it again.

As shown in FIG. 7, the good product module did not satisfy the starting current and the hysteresis condition among the specifications shown in Table 1 of the performance test results.

In other words, hysteresis occurred in the section where the displacement of the foreign matter mixed failure module was hardly occurred after the rise.

In addition, the foreign matter mixing failure module has a natural frequency of about 70 Hz or more in the spectrum analysis in the step d), and a harmonic peak in the integer part of 70 Hz in the FFT analysis result through the step e) .

According to the result of the experiment, in the step f) of the defect diagnosis method of the autofocus module according to the present invention, the displacement of the autofocus module 10 according to the driving current in the step h) When hysteresis occurs, it is determined that the foreign object is mixed with the auto focus module 10.

Accordingly, in the defect diagnosis method and the defect diagnosis apparatus of the mobile VCM module according to the present invention, not only the failure of the auto focus module is determined by the driving performance test according to the current change, but also, It is possible to satisfy the stringent performance evaluation criterion according to the performance enhancement of the mobile device to which the auto focus module is applied and it is possible to satisfy the reliability evaluation through accurate defect judgment and defect cause estimation Can be improved.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It goes without saying that various modifications can be made.

1: Fault diagnosis device of autofocus module
10: Auto focus module
11: Cover 12: Holder
13: inner yoke 14: outer yoke
15: permanent magnet 16: coil
17: carrier 18: upper spring
19: Lower spring
100: Fixing jig
200: Laser displacement sensor
300:
310: control unit 320: DAQ system
330: Positioning stage
400: signal supply means
410: Power Supply 420: Dynamic Signal Analyzer
500: High-speed shooting means

Claims (8)

A method for diagnosing a defect in an autofocus module,
a) fixing an auto focus module to a fixing jig and adjusting an initial position;
b) powering said autofocus module by signal supply means;
c) supplying a current signal having a predetermined frequency to the autofocus module by the signal supply means;
d) analyzing natural frequency characteristics from the autofocus module measurement signal synchronized with the current signal;
e) analyzing Fast Fourier Transform (FFT) characteristics of the autofocus module;
f) comparing the analysis result of the measured auto focus module with the analysis result of the existing good auto focus module to judge the failure;
The method comprising the steps of:
The method according to claim 1,
The defect diagnosis method of the autofocus module
After the step b)
g) stepping up or down the current supplied to the autofocus module by the signal supply means step by step;
h) measuring a displacement according to a driving current by a displacement sensor mounted on the upper side of the autofocus module; The method comprising the steps of:
3. The method of claim 2,
In the step f)
Wherein the autofocus module estimates a cause of the failure of the autofocus module when the displacement of the autofocus module according to the driving current is measured and hysteresis of a specific section is generated in the created graph in the step h) Diagnostic method.
The method according to claim 1,
In the step d)
After offset and displacement setting, a spectrum signal is applied by applying a current signal having a constant frequency,
And the magnitude response to the frequency is tabulated.
The method according to claim 1,
In the step e)
Wherein a harmonic peak is detected at a frequency which is an integral multiple of the frequency of the auto focus module if the auto focus module is a good product.
5. The method according to any one of claims 4 and 5,
In the step f)
As a result of the spectrum analysis in the step d), the size response peak of the Bode diagram appears as a multi-peak at a higher frequency than that of a good product,
As a result of the FFT characteristic analysis of step e), when a subharmonic is detected,
And determines that some parts of the auto-focus module are defective in connection. delete delete

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