JP5662174B2 - AF lens unit characteristic inspection apparatus, characteristic inspection method, control program, and readable storage medium - Google Patents

Description

  The present invention relates to an AF lens unit characteristic inspection apparatus and characteristic inspection method for inspecting optical characteristics of a lens and drive characteristics of a lens driving device, a control program for causing a computer to execute the steps of the characteristic inspection method of the AF lens unit, The present invention relates to a computer-readable readable storage medium in which the control program is stored.

  Conventionally, in order to inspect the characteristics of a lens, a lens measuring device for inspecting a MTF (Modulation Transfer Function) of a lens as described in Patent Document 1 is known. The MTF is a value indicating how much resolution can be obtained through the lens. This lens measuring device allows light such as a halogen lamp to enter a test lens arranged in the inspection device via a reference chart and detect a light image emitted from the test lens with a solid-state imaging device. The MTF and MTF-defocus characteristics of the lens to be examined are inspected. In the characteristic inspection of the AF driving device, a predetermined driving signal is input to the AF driving device, and the position of the driving unit of the AF driving device is inspected by a non-contact displacement meter.

  In any case, when inspecting the performance of the camera module, the characteristics of the VCM (voice coil motor) actuator (relationship between applied current and drive amount) are inspected, and the optical characteristics (MTF) of the lens are inspected. Sometimes there is a need for an inspection device. A lens measuring device for measuring the MTF (resolution) of the optical characteristics of the lens is disclosed in FIG.

  FIG. 9 is a schematic configuration diagram of a conventional lens measuring device disclosed in Patent Document 1. In FIG.

  In FIG. 9, a conventional lens measuring device 100 is a device that measures the MTF of the optical characteristics of the lens 101. A large number of lenses 101 as measurement objects are held on the tray 107 and measured. The tray 107 is a structure that supports the lens 101 so that light can be transmitted.

  The measurement unit 102 is provided with an XY stage 108 on which the tray 107 is placed. The XY stage 108 is configured to place the tray 107 and to move the tray 107 in the left-right direction that is the X direction and the front-back direction that is the Y direction. The XY stage 108 moves the lens 101 to be measured by moving the tray 107.

  The XY stage 108 is provided with a detection unit 108 a that detects the type of the lens 101 held on the tray 107. The detection unit 108 a detects the type of the lens 101 held by the tray 107 based on information from the identification unit 107 a provided on the tray 107. The detection unit 108 a detects the identification number of the tray 107 based on information of the identification unit 107 a provided on the tray 107.

  A chart 109 is arranged in the measurement unit 102. The chart 109 is arranged between the integrating sphere 110 and the lens 101. The measurement unit 102 measures the optical characteristics of the lens 101 by back projection. That is, the chart 109 for projecting an optical image onto the lens 101 is disposed at the focal position of the lens 101.

  The chart 109 is attached to the Z stage 111. The Z stage 111 is configured to be able to move the chart 109 in the vertical direction that is the Z direction. By moving the chart 109 closer to or away from the lens 101, the position of the chart 109 relative to the lens 101 is adjusted.

  An integrating sphere 110 is installed in the measurement unit 102. The integrating sphere 110 is a light source that emits input light toward the chart 109. The integrating sphere 110 is attached to a lower position of the chart 109, for example. The integrating sphere 110 is a sphere having an output port 110a and having a diffusion surface 110b formed on the inner surface. The light emitted from the light source unit 112 enters the integrating sphere 110 through the light guide 113. The light incident on the integrating sphere 110 is repeatedly reflected inside the integrating sphere 110, and is emitted upward from the output port 110a as light with very little light amount unevenness.

  In the measurement unit 102, three cameras 114 are installed. The camera 114 is an imaging unit that receives an output image output from the lens 101. As the camera 114, for example, a camera provided with a solid-state imaging device such as a CCD (Charge Coupled Device) is used. The output image of the lens 101 is an image in which the input image of the chart 109 input to the lens 101 is formed on the camera 114 by the lens 101. An image reception signal of the camera 114 is input to the analysis control unit 103.

  A drive unit 115 is installed in the power supply unit 106. The drive unit 115 performs drive control of the XY stage 108 and the Z stage 111. The drive unit 115 outputs drive signals to the XY stage 108 and the Z stage 111 according to the control signal output from the analysis control unit 103. The power supply unit 106 is provided with a control unit 116. The control unit 116 mainly performs light emission control of the light source unit 112. Further, the control unit 116 inputs a detection signal of the detection unit 108 a of the XY stage 108 and outputs the detection signal to the analysis control unit 103. The power supply unit 106 is provided with a power supply 117. The power supply unit 106 is provided with a fan 118.

  The analysis control unit 103 recognizes the type of the lens 101 to be measured based on the information of the tray 107 attached to the measurement unit 102, and sets the measurement of the lens optical characteristic (MTF) according to the type of the lens 101. Functions as measurement setting means. For example, measurement setting data corresponding to the type of the lens 101 is registered in the analysis control unit 103. Specifically, position setting data of the chart 109 corresponding to the type of the lens 101, movement position data of the XY stage 108 corresponding to the type of the tray 107, and the like are registered. The analysis control unit 103 functions as an analysis unit that receives an image reception signal of the camera 114 and analyzes the optical characteristics of the MTF value of the lens 101 based on the image reception signal.

  The monitor 104 is connected to the analysis control unit 103 and functions as a display unit that displays the measurement result of the optical characteristic (MTF value) of the lens 101. The monitor 104 also displays a measurement setting when measuring the MTF value of the lens 101.

  When the measured tray 107 is placed on the determination unit 105, the recognition unit 105 a recognizes the tray 107 based on the identification unit 107 a of the tray 107. The measurement result of each lens 101 held on the tray 107 is acquired from the analysis control unit 103, and the display unit 105b displays the lens 101 of the measurement result NG in a specific color. For example, the display unit 105b is provided with a plurality of light emitters corresponding to the arrangement positions of the respective lenses 101 of the tray 107, and causes the light emitters corresponding to the NG lenses 101 to emit red light. As a result, the operator of the apparatus can easily determine the lens 101 whose measurement result is NG from the plurality of held lenses 101, and can remove the NG lens 101 from the tray 107.

  Next, in Patent Document 1, the MTF is measured with the lens 101 alone and the autofocus mechanism is provided on the lens measuring device 100 side. However, in Patent Document 2, a camera having an autofocus mechanism is used. This is a case of measuring the MTF of this lens, which is disclosed in detail in FIG.

  FIG. 10 is a schematic configuration diagram of a conventional camera MTF measuring machine disclosed in Patent Document 2. In FIG.

  In FIG. 10, a conventional camera MTF measuring machine 200 includes an inspected camera 203 in which an autofocus mechanism 201 and a zoom lens 202 are incorporated, an image sensor 208 provided on a film surface of the inspected camera 203, and an arithmetic unit. 204 and a chart unit 205 having inspection charts 205a and 205b for forming an inspection chart image on the film surface of the camera 203 to be inspected. The autofocus mechanism 201 measures the distance to the subject using the principle of triangulation using infrared light projection.

  With the above configuration, first, the inspected camera 203 is focused using the autofocus mechanism 201. FIG. 8 is a top view showing this state. The camera 203 to be inspected is installed in a state where the photographing magnification is set to correspond to the distance to the inspection chart unit 205 by extending the zoom lens 202. The cylinder 209 operates upward in FIG. 8, and the center inspection chart 205a is retracted from the optical axis. The cylinder 211 operates in the upward direction of FIG. 8, and the target plate 210 is located on the optical axis.

  In this state, the photographing operation is performed in the valve mode so that the autofocus mechanism 201 of the camera 203 to be inspected is operated and at the same time the shutter is opened. When the infrared light projected from the autofocus mechanism 201 is reflected by the target plate 210, the distance between the camera 203 to be inspected and the target plate 210 is measured using the triangulation principle. Based on the distance information thus obtained, the lens built in the zoom lens 202 is driven to focus the camera 203 to be inspected. With this operation, the focus of the camera 203 to be inspected is in a state of being in alignment with the target plate 210.

  Next, the cylinder 211 is moved downward to retract the target plate 210 from the optical axis, and at the same time, the cylinder 209 is operated downward to position the center inspection chart 205a on the optical axis. In this case, since the central inspection chart 205a is located at the same position as the target plate 210, the camera 203 to be inspected is in focus on the central inspection chart 205a.

  In this state, an image of the center inspection chart 205a formed on the film equivalent surface 207 is taken by the image sensor 208, and the MTF value is calculated by the arithmetic unit 204 from the contrast of this image. Similarly, the MTF value in the peripheral part is also calculated from the image formed on the film equivalent surface 207 of the peripheral inspection chart 205b.

  Therefore, by focusing on the target plate 210 using the autofocus mechanism 201 built in the camera to be inspected 203, the center inspection chart 205a is focused as a result. The imaging performance of the camera in consideration of the accuracy of the autofocus mechanism 201 built in the camera 203 to be inspected by analyzing the inspection chart images of the center chart 205a and the peripheral inspection chart 205b and calculating the MTF value. The camera MTF measuring device 200 that can be evaluated can be obtained.

JP 2007-315959 A JP 2002-357506 A

  However, in each of the conventional configurations disclosed in Patent Documents 1 and 2, the characteristics of the VCM (voice coil motor) actuator (relationship between applied current and drive amount) are obtained only by measuring the MTF value of the lens. The inspection must be performed by a separate inspection device. That is, in the conventional method described above, dedicated inspection and measurement devices for the lens and the AF driving device are required. This required a lot of inspection man-hours.

  A method of inspecting the characteristics of the AF drive device with a defocus curve of the MTF instead of the displacement distance of the AF drive device is also conceivable. Accordingly, it is considered that it is not necessary to install a lens inspection device for measuring the MTF of the lens and an AF driving device inspection device for inspecting the relationship between the applied current and the driving amount, on one line. However, when the lens inspection device and the AF drive device inspection device are used in common, the characteristics of the AF drive device at the INF distance can be confirmed, but at the macro distance, the characteristics of the AF drive device at the INF distance are confirmed. Can not be inspected.

  In the MTF-defocus curve when there is a start hook on the forward path and the return path, the start hook can be detected, but in the case of the return path start hook, the MTF value is low and cannot be detected. When performing inspection at this macro position, it is necessary to set the position of the reference chart to macro and switch the focal length of the measurement lens to the macro distance.

  It is also possible to acquire a focus curve (MTF-applied current) by a resolution inspection apparatus. It is also possible to simply inspect the actuator characteristics (applied current-drive amount) by calculating the lens feed amount (drive amount) from the MTF of the focus curve. However, since the chart is set at a predetermined distance (mostly in the vicinity of INF), a focus curve before and after the chart can be acquired. However, since the resolving power is significantly reduced on the macro side, the focus curve does not appear. As a result, it is difficult to inspect the characteristics of the actuator throughout the drive of the actuator.

  The present invention solves the above-mentioned conventional problems, and the MTF characteristic inspection of the lens and the AF drive device characteristics (relationship between applied current and drive amount) are simultaneously performed by one inspection device, thereby greatly reducing the inspection man-hours. AF lens unit characteristic inspection device and characteristic inspection method thereof, control program for causing a computer to execute the steps of the characteristic inspection method of the AF lens unit, and computer-readable readable storage storing the control program The purpose is to provide a medium.

  An AF lens unit characteristic inspection apparatus according to the present invention includes: an imaging lens; and an AF lens unit characteristic inspection apparatus having an AF driving device for moving the imaging lens back and forth in the forward path and the backward path to adjust the focus. By changing the frequency of MTF calculation at the time of resolution inspection of the imaging lens and at the time of characteristic inspection of the displacement amount of the driving unit of the AF driving device in the forward movement, and at the time of characteristic inspection of the displacement amount of the driving part in the backward movement The MTF value corresponding to the input current value to the AF lens unit is calculated to inspect the resolution of the imaging lens, and the displacement amount characteristic inspection of the driving unit of the AF driving device relative to the input current value to the AF driving device It has the characteristic inspection means which performs, and the said objective is achieved by it.

  In the AF lens unit characteristic inspection apparatus of the present invention, it is preferable that the characteristic of the displacement of the drive unit during the backward movement is more during the inspection of the resolution of the imaging lens and the drive unit during the forward movement. When the frequency of MTF calculation is set lower than that during the characteristic inspection of the displacement amount, the characteristic inspection of the displacement amount of the driving unit with respect to the input current value to the AF driving device is performed when the resolution of the imaging lens is inspected. Do it at the same time.

  More preferably, the frequency of MTF calculation is set lower in the MTF characteristic macro region in the AF lens unit characteristic inspection apparatus of the present invention than in the INF region of the MTF characteristic.

  Further preferably, the characteristic inspection of the displacement amount of the drive unit in the characteristic inspection device of the AF lens unit according to the present invention is based on the presence / absence of at least one of the forward start catching characteristic and the backward start catching characteristic of the drive unit. Do.

  Still preferably, in the AF lens unit characteristic inspection apparatus according to the present invention, the characteristic inspection means includes an imaging sensor disposed opposite to one side of the AF lens unit and an opposite side of the AF lens unit. A reference chart arranged; an AF drive control circuit for controlling AF drive of the AF drive apparatus; and the reference chart from the imaging sensor corresponding to an input current value from the AF drive control circuit to the AF drive apparatus. An MTF arithmetic unit that calculates an MTF value for the input current value based on the image data, and performs a characteristic inspection of a displacement amount of a driving unit of the AF driving device with respect to the input current value.

  Further preferably, the reference chart in the AF lens unit characteristic inspection apparatus of the present invention is printed with slits or edges, and is arranged at a sensor position when the AF lens unit is incorporated in a camera module.

  Still preferably, in an AF lens unit characteristic inspection apparatus according to the present invention, the imaging sensor is a solid-state imaging device in which a plurality of light receiving units that photoelectrically convert image light from the reference chart is arranged in a two-dimensional matrix. And a signal processing unit that performs predetermined signal processing on each imaging signal from the plurality of light receiving units of the solid-state imaging device to obtain a series of image data.

  Still preferably, in an AF lens unit characteristic inspection apparatus according to the present invention, the MTF arithmetic unit may perform an operation on the input current value based on the image data from the imaging sensor corresponding to the input current value from the AF drive control circuit. The MTF value is calculated to determine the MTF peak value, and the MTF peak value is compared with a predetermined reference value to determine whether the resolution of the lens characteristics is good or bad.

  Still preferably, in an AF lens unit characteristic inspection apparatus according to the present invention, the MTF arithmetic unit determines whether or not at least one of the forward start trigger characteristic and the backward start trigger characteristic of the drive unit of the AF drive unit is present. Detection is performed, and a characteristic inspection of the displacement amount of the driving unit of the AF driving device is performed with a predetermined magnitude of the forward path start catching characteristic and the backward path start catching characteristic as threshold values.

  Further, preferably, at the time of inspection of the resolution of the imaging lens by the MTF value in the characteristic inspection device of the AF lens unit of the present invention and at the time of inspection of the forward start catching characteristic, the MTF value is narrowed to narrow the peak width of the MTF value The frequency of calculation is set to 80 to 200 LP / mm, and the frequency of MTF calculation is set to 5 to 20 LP / mm in order to widen the peak width of the MTF value at the time of inspecting the backward start catching characteristic. LP / mm is a unit indicating how many black / white line pairs exist per 1 mm.

  According to the AF lens unit characteristic inspection method of the present invention, in the AF lens unit characteristic inspection method provided with an AF driving device for focusing by moving the imaging lens back and forth in the forward path and the backward path, the resolution of the imaging lens Characteristic inspection means by changing the frequency of MTF calculation at the time of inspection and at the time of characteristic inspection of the displacement amount of the driving unit of the AF drive device during forward movement and at the time of characteristic inspection of the displacement amount of the driving part during backward movement Calculates the MTF value with respect to the input current value to the AF lens unit to inspect the resolution of the imaging lens, and the characteristics of the displacement of the driving unit of the AF driving device with respect to the input current value to the AF driving device It has a characteristic inspection step for performing inspection, whereby the above-mentioned object is achieved.

  Preferably, in the characteristic inspection step of the characteristic inspection method of the AF lens unit according to the present invention, the characteristic inspection of the displacement amount of the driving unit in the backward movement is performed during the inspection of the resolution of the imaging lens and the forward movement. By setting the frequency of the MTF calculation to be lower than that at the time of the characteristic inspection of the displacement amount of the driving unit in the lens, the characteristic inspection of the displacement amount of the driving unit with respect to the input current value to the AF driving device is performed. At the same time when inspecting.

  Further, preferably, the frequency of MTF calculation is set lower in the MTF characteristic macro region in the AF lens unit characteristic inspection method of the present invention than in the MTF characteristic INF region.

  Further preferably, the characteristic inspection of the displacement amount of the drive unit in the AF lens unit characteristic inspection method of the present invention is based on the presence or absence of at least one of the forward start trigger characteristic and the return start trigger characteristic of the drive unit. Do.

  Further preferably, in the characteristic inspection method of the AF lens unit according to the present invention, the peak width of the MTF value is narrowed at the time of inspection of the resolution of the imaging lens by the MTF value and at the time of inspection of the forward start catching characteristic. In addition, the frequency of MTF calculation is set to 80 to 200 LP / mm, and the MTF calculation frequency is set to 5 to 20 LP / mm in order to widen the peak width of the MTF value at the time of inspecting the backward start catching characteristic.

  The control program according to the present invention describes a processing procedure for causing a computer to execute the steps of the characteristic inspection method for the AF lens unit according to the present invention, thereby achieving the above object.

  The readable storage medium of the present invention is a computer-readable storage medium storing the control program of the present invention, thereby achieving the above object.

  With the above configuration, the operation of the present invention will be described below.

  In the present invention, the frequency of MTF calculation is determined during the resolution inspection of the imaging lens and during the characteristic inspection of the displacement of the driving unit of the AF drive device in the forward movement and during the characteristic inspection of the displacement of the driving unit during the backward movement. By changing, the MTF value for the input current value to the AF lens unit is calculated to inspect the resolution of the imaging lens, and the characteristic inspection of the displacement amount of the driving unit of the AF driving device with respect to the input current value to the AF driving device is performed. It has characteristic inspection means to perform.

  Accordingly, the frequency of the MTF calculation when inspecting the return path start hook in the characteristic inspection of the displacement amount of the drive unit is compared with the frequency of the MTF calculation at the time of inspecting the forward path start hook or at the resolution inspection of the imaging lens. By setting it low, it is possible to perform the MTF resolution inspection of the lens and the driving hook inspection with the same inspection device as the characteristic inspection of the AF driving device in the forward path and the backward path. As a result, the number of inspection steps can be greatly reduced.

  As described above, according to the present invention, the MTF calculation is performed more in the characteristic inspection of the displacement amount of the driving unit in the backward movement than in the characteristic inspection of the displacement amount of the driving unit in the outward movement and the inspection of the resolution of the imaging lens. By setting the frequency low, the MTF characteristic inspection of the imaging lens and the AF drive device characteristics (relationship between applied current and drive amount) can be performed simultaneously by one inspection device, and the inspection man-hours can be greatly reduced.

It is a principal part block diagram which shows typically the characteristic inspection apparatus of the AF lens unit in Embodiment 1 of this invention. It is a figure which shows the graph of the input signal-drive part displacement amount in the drive part of AF drive apparatus of FIG. It is a figure which shows the graph of MTF-defocus when a lens is driven with the drive part of the AF drive device of FIG. It is a figure which shows the graph of the MTF-defocus characteristic in a reciprocating operation when there exists a catching curve in the drive part of the AF drive device of FIG. It is a figure which shows the graph of the MTF-defocus characteristic at the time of making the frequency of MTF calculation low with the MTF arithmetic unit of FIG. FIG. 2 is a graph showing an MTF-defocus characteristic graph of a lens having a focal length of 5 mm and F2.8 as the lens of FIG. 1, and FIG. (B) shows the case where the MTF value is zero and the MTF calculation frequency is 10 LP / mm, and the maximum extension (top surface) position of the actuator is 0.3 mm. It is a figure which shows the case where has come out. 2 is a flowchart showing an operation example of start and top surface catching determination performed by the MTF arithmetic device with respect to the AF lens unit of FIG. 1. FIGS. 2A and 2B are diagrams illustrating a relationship between an MTF value and an input current value to the driving unit of the AF lens unit in FIG. 1, in which FIG. These are figures which show the top surface catching symptom 2. FIG. It is a schematic block diagram of the conventional lens measuring apparatus currently disclosed by patent document 1. FIG. It is a schematic block diagram of the conventional camera MTF measuring machine currently disclosed by patent document 2. FIG. It is a figure which shows the relationship between a spatial frequency (LP / mm) and MTF of a lens.

  Hereinafter, a first embodiment of the characteristic inspection apparatus and characteristic inspection method for an AF lens unit according to the present invention will be described in detail with reference to the drawings. In addition, each thickness, length, etc. of the structural member in each figure are not limited to the structure to illustrate from a viewpoint on drawing preparation.

(Embodiment 1)
FIG. 1 is a main part configuration diagram schematically showing an AF lens unit characteristic inspection apparatus according to Embodiment 1 of the present invention.

In FIG. 1, an AF lens unit 1 to be inspected includes an imaging lens 1a and an AF driving device 1b having a driving unit such as a VCM (voice coil motor) or a stepping motor for moving the position of the imaging lens 1a. ing. The characteristic inspection apparatus 10 of the AF lens unit 1 according to the first embodiment is opposed to the measurement lens 2 arranged on one side (upper side in the drawing) of the AF lens unit 1 to be inspected and one side of the AF lens unit 1. Based on the image data of the measurement sensor 3 as the imaging sensor arranged in the above, the reference chart 4 arranged opposite to the other side of the AF lens unit 1, and the reference chart 4 from the measurement sensor 3, the AF lens unit MTF calculation for calculating the MTF value for the input current value to 1 and checking the resolution of the imaging lens 1a , and for checking the characteristics of the displacement of the drive unit of the AF drive device 1b for the input current value to the AF drive device 1b A device 6 and an AF drive control circuit 7 for controlling AF drive of the AF drive device 1b are provided.

The measurement lens 2, the measurement sensor 3, the reference chart 4, the MTF arithmetic unit 6, and the AF drive control circuit 7 constitute a characteristic inspection unit. This characteristic inspection unit allows the imaging lens 1a to be inspected at the time of resolution inspection and on the forward path. The input current to the AF lens unit 1 is changed by changing the frequency of the MTF calculation between the characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b during movement and the characteristic inspection of the displacement amount of the driving unit during backward movement. The MTF value with respect to the value is calculated to inspect the resolution of the imaging lens 1a , and the characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b with respect to the input current value to the AF driving device 1b is performed.

By setting the frequency of the MTF calculation lower during the characteristic inspection of the displacement amount of the driving unit in the backward movement than in the inspection of the resolution of the imaging lens 1a and during the characteristic inspection of the displacement amount of the driving part in the forward movement, The characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b with respect to the input current value to the AF driving device 1b is simultaneously performed when the resolution of the imaging lens 1a is checked. That is, the MTF inspection frequency is set lower in the MTF characteristic macro area than in the MTF characteristic INF area. The characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b is performed by at least one of the forward start catching characteristic and the backward starting catching property of the driving unit of the AF driving device 1b. Alternatively, it is performed depending on whether or not there is a starting catch on at least one of the forward path and the return path.

  The measuring lens 2 has a focal position at infinity.

  The measurement sensor 3 includes a solid-state image sensor in which a plurality of light-receiving units that photoelectrically convert image light from the reference chart 4 is arranged in a two-dimensional matrix, and each imaging from the plurality of light-receiving units of the solid-state image sensor. A signal processing unit that performs predetermined signal processing on the signal to obtain a series of image data.

  The reference chart 4 is printed with slits or edges, and is arranged at the sensor position when the AF lens unit 1 is incorporated in the camera module.

  The MTF calculation device 6 calculates the input current value−MTF value based on the image data from the measurement sensor 3 corresponding to the input current value from the AF drive control circuit 7, and the MTF curve 11 shown in FIG. When the MTF peak value (INF position) is equal to or greater than a predetermined threshold, there is no problem, and when the MTF peak value is smaller than the predetermined threshold, the lens characteristics are poor (NG). Is determined.

  In this MTF arithmetic unit 6, when the image data from the measurement sensor 3 is analog data, the input signal is amplified through an amplifier, the amplified data is frequency-converted, and converted into a line pair from the time axis for MTF calculation. The MTF value corresponding to the frequency is calculated. When the image data from the measurement sensor 3 is digital data, an MTF value corresponding to the frequency of MTF calculation can be obtained by passing the input signal through an FFT (Fourier transform element).

  At this time, in the MTF curve 11 of the input current value−MTF value, the starting catch curves 12 and 14 of the forward path and the backward path are also examined. At the time of the MTF inspection and the inspection of the starting start catching curve (starting catching curve 13), the frequency of the MTF calculation may be set to about 80 to 200 LP / mm (here, 140 LP / mm in FIG. 6) in order to narrow the peak width. desirable. LP / mm in this case indicates how many black-white line pairs are included in 1 mm. In the normal measurement sensor 3, since one pixel is usually included up to about 250 to 300 LP / mm, it can be detected. Further, at the time of inspection of the return path start hook curve (start hook curve 14), the rough frequency of the MTF calculation that can detect the return path start hook curve (start hook curve 14) is 5 to 20 LP / mm (here, FIG. 6). 10 LP / mm) is desirable. With such a rough frequency of MTF calculation, it is possible to detect the return path start hook curve (start hook curve 14). The high frequency and low frequency of these MTF calculations do not need to replace the reference chart 4 and can include a plurality of frequencies by applying a Fourier transform to the cross or coarse pattern during the MTF calculation. From this, it is possible to extract the high frequency and low frequency of the MTF calculation. In short, instead of changing the reference chart 4, the high and low frequencies of the desired MTF calculation can be extracted and used by Fourier transforming the pattern of the reference chart 4.

  The AF drive control circuit 7 inputs an input signal (current signal) to the VCM (voice coil motor) of the AF drive device 1b, thereby moving the drive unit of the AF drive device 1b forward or retracting a predetermined amount. Thus, the lens position is controlled.

  With the above configuration, first, the light emitted from the light source 5 passes through the reference chart 4 and enters the lens 1 a from the reference chart 4. If the reference chart 4 is at the sensor position at the time of photographing the lens 1a at infinity, the light emitted from the lens 1a becomes substantially parallel light. For this reason, the parallel light from the lens 1 a is incident on the measurement lens 2 and an image of the reference chart 4 can be formed on the surface of the measurement sensor 3.

  Next, image data from the measurement sensor 3 is input to the MTF arithmetic device 6, and the MTF arithmetic device 6 calculates an input current value−MTF value based on the image data.

  On the other hand, with regard to the characteristic inspection of the AF drive device 1b, conventionally, a predetermined drive signal (input signal) is input from the AF drive control circuit 7 to the AF drive device 1b, and a current value corresponding to the input signal is determined. The displacement position of the driving unit of the AF driving device 1b was inspected by a non-contact displacement meter (not shown) such as a laser displacement meter. When the input signal request is, for example, 2 mm movement, whether or not the displacement position of the driving unit of the AF driving device 1b measured by a non-contact displacement meter (not shown) has moved within the specified movement error range. It was judged pass / fail. The amount of movement of the drive unit changes in proportion to the current value of the input signal passed through the VCM (voice coil motor) of the AF drive device 1b.

  FIG. 2 shows a graph of the input signal-drive unit displacement amount of the AF drive device 1b of FIG. A displacement curve 21 represents an ideal displacement characteristic curve. Even if a predetermined input signal (predetermined current value) is applied to the AF drive device 1b with respect to the ideal displacement curve 21, the drive unit starts to move forward and the phenomenon of the forward start catching curve 22 occurs. If there is, a hysteresis such as a broken line (a region that cannot come linear) is generated, and if there is a return path start catching curve 23, a hysteresis (a region that cannot come linear) occurs as shown by a broken line.

  FIG. 3 shows a graph of MTF-defocus when the lens 1a is driven by the AF driving device 1b of FIG. Usually, the AF lens unit 1 is in a state called over INF (the MTF peak value is at the INF position, but the start position is not the INF position, and the position slightly advanced from the start position is the INF position). The assembly is adjusted. When the lens 1a is slightly moved by the AF driving device 1b as in the MTF curve 11 shown in FIG. 3, the MTF value shows a peak (INF position), and then the MTF value decreases monotonously. The resolution of the lens can be inspected depending on whether the MTF peak value (INF position) of the MTF curve 11 exceeds the reference value (threshold value).

  FIG. 4 shows a graph of the MTF-defocus characteristic in the reciprocating operation when the AF driving device 1b of FIG. With respect to the ideal curve of the MTF curve 11, there is a characteristic of the starting catching curve 12 indicated by a broken line in the forward path, and there is a case where hysteresis (an area where linear cannot come) occurs in the forward path and the return path. By detecting this hysteresis (region that cannot come linearly), it is possible to detect a failure in the forward start catching curve (starting catching curve 12) of the AF drive device 1b. That is, the MTF curve 11 can be obtained only by the MTF arithmetic unit 6 without using a non-contact displacement meter (not shown) as in the prior art for the characteristic inspection of the AF driving device 1b. Thus, it is possible to determine whether or not the AF drive device 1b is defective by detecting the presence or absence of at least one of the start catch curves 12 and 14 from the MTF curve 11. In this case, it is possible to determine a failure by using a predetermined magnitude of the starting catch curves 12 and 14 as a threshold value. For example, if the generation range of the start catch curves 12 and 14 is within the stroke margin range, it can be treated as a non-defective product. In the first place, the presence or absence of the starting catch curves 12 and 14 is inspected because the adhesive scatters during the final inspection of the actuator with the lens after the lens 1a and the AF driving device 1b are fixed with the adhesive. , 14 may be caused.

  The return path start catching curve does not have sufficient detection capability because the MTF value is low. When dust or the like adheres to the driving part of the AF driving device 1b, such as the start catching curve 12, the adhesive force is generated due to the adhesion of the dust, and the driving part of the AF driving device 1b starts to move. Phenomena that become difficult or move so as to return to the original position at once by an input signal (current value) of a predetermined value or more occur. The position of the drive unit is determined by the magnetic balance depending on the value of the current passed through the VCM (voice coil motor) of the AF drive device 1b, so that the original position can be returned to the original position at once by a predetermined input signal (current value). It moves to.

  FIG. 5 shows a graph of MTF-defocus characteristics when the frequency of MTF calculation is lowered in the MTF arithmetic unit 6 of FIG. In FIG. 5, the frequency of the MTF calculation is set low when the return path start catching curve 14 starts the return path. In FIG. 5, an MTF curve 13 is an ideal curve, and a start catching curve 14 indicated by a broken line is a return start catching curve. A comparison between the MTF curve 11 and the MTF curve 13 shows that the MTF curve 13 has a small amount of change from the start to the peak, and therefore does not have sufficient detection capability with respect to the forward start trigger curve (start trigger curve 12). On the contrary, since a sufficient MTF value remains even at the macro position, the return path start catch curve (start catch curve 14) has a sufficient detection capability.

  At the time of MTF inspection and the inspection of the starting start catching curve (starting catching curve 13), it is desirable to set the frequency of MTF calculation to about 80 to 200 LP / mm in order to narrow the peak width. Further, at the time of inspection of the return path start hook curve (start hook curve 14), it is desirable to set the frequency of MTF calculation to 5 to 20 LP / mm. The MTF may be SFR or CTF.

  FIG. 6 shows a graph of the MTF-defocus characteristic of a lens having a focal length of 5 mm and F2.8 as the lens 1a in FIG. 1. FIG. 6A shows the MTF calculation frequency of 140 LP / mm and the actuator 1 The maximum extension (top surface) position = 0.3 mm and the MTF value is zero. (B) shows that the frequency of MTF calculation is 10 LP / mm and the maximum extension (top surface) position of the actuator = 0.3 mm. The case where the MTF value is output is shown.

Here, the MTF calculation device 6 checks the frequency of MTF calculation when inspecting the return path start hook (start hook 14), the MTF value calculation, and the forward path start hook (start hook 13). By setting the frequency lower than the frequency of the MTF calculation at the time, the input current value to the AF lens unit 1 is determined based on the image data of the reference chart 4 from the measurement sensor 3 with respect to the input current value to the AF driving device 1b. The MTF value is calculated to inspect the resolution of the imaging lens 1a , and the characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b with respect to the input current value to the AF driving device 1b is performed. The software configuration of the MTF arithmetic unit 6 will be described below.

  Although not specifically shown here, the MTF arithmetic unit 6 is a computer-readable readable recording medium in which a CPU (central processing unit) having the functions of the MTF arithmetic unit 6 and a control program and its data are stored. And a RAM serving as a storage unit that functions as a work memory from which a control program and its data are read out at the start-up and read and stored for each control by the CPU.

  The ROM as the readable recording medium may be composed of a hard disk, a formable optical disk, a magneto-optical disk, a magnetic disk, and an IC memory. This control program and its data are stored in the ROM, but this control program and its data may be downloaded to the ROM 4 from another readable recording medium or via wireless, wired or the Internet.

The characteristic inspection method of the AF lens unit 1 according to the first embodiment is performed when the imaging lens 1a is inspected for resolution and during the characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b in the forward movement, and in the AF driving device 1b in the backward movement. By changing the frequency of the MTF calculation at the time of the characteristic inspection of the displacement amount of the drive unit, the characteristic inspection means of the CPU calculates the MTF value for the input current value to the AF lens unit 1 based on the control program and its data. It has a characteristic inspection step for inspecting the resolution of the imaging lens 1a by calculation, and performing characteristic inspection of the displacement amount of the driving unit of the AF driving device 1b with respect to the input current value to the AF driving device 1b.

In this characteristic inspection step, towards the time characteristic test of displacement of the driving part of the AF driving apparatus 1b in the backward movement, the displacement amount of the driving unit of the AF driving apparatus 1b in the test and during the forward movement of the resolution of the image pickup lens 1a By setting the frequency of the MTF calculation lower than that at the time of the characteristic inspection, the characteristic inspection of the displacement of the driving unit of the AF driving device 1b with respect to the input current value to the AF driving device 1b is performed, and the resolution of the imaging lens 1a is checked Sometimes done at the same time.

  FIG. 7 is a flowchart showing an operation example of start and top surface catching determination performed by the MTF arithmetic unit 6 for the AF lens unit 1 of FIG.

  First, as shown in FIG. 7, the current value ImA supplied from the AF drive control circuit 7 to the drive unit of the AF drive device 1b in step S1 is set to “ImA = 0”, and in step S2, the MTF arithmetic unit 6 performs the MTF. The value is measured and stored in a predetermined storage unit.

  Next, in step S3, the current value ImA supplied from the AF drive control circuit 7 to the drive unit of the AF drive device 1b is increased by “1 mA = ImA + 1”. In step S4, the increased current value “ImA + 1” is supplied to the driving unit of the AF driving device 1b, thereby moving the lens 1a forward by one step.

  Subsequently, “ImA ≦ ImAmax” is determined in step S5 to determine whether or not the current value ImA of the input signal supplied from the AF drive control circuit 7 to the drive unit of the AF drive device 1b is equal to or less than the maximum current value ImAmax. In the case of “ImA ≦ ImAmax” in Step S5 (YES), the process proceeds to Step S2 and a series of processing is repeated, and the current value ImA of the input signal exceeds the maximum current value ImAmax, and “ImA ≦ ImAmax” If not (NO), the process proceeds to step S6. In step S6, the MTF arithmetic unit 6 measures the MTF value and stores it in a predetermined storage unit. This completes the outbound inspection and shifts to the inbound inspection.

  Thereafter, in step S7, the current value ImA supplied from the AF drive control circuit 7 to the drive unit of the AF drive device 1b is decreased by "1mA = ImA-1". In step S8, the reduced current value “ImA-1” is supplied to the driving unit of the AF driving device 1b, thereby moving the lens 1a backward by one step.

  In step S9, it is determined whether or not the current value ImA of the input signal supplied from the AF drive control circuit 7 to the drive unit of the AF drive device 1b is “ImA ≧ 0”. If “ImA ≧ 0” in step S9 (YES), the process proceeds to step S6 and a series of processing is repeated, and the current value ImA of the input signal becomes 0 or less and does not satisfy “ImA ≧ 0”. The process proceeds to the determination process in step S10 (NO).

  In the determination process of step S10, if the absolute value of the data difference between the forward path Ya and the backward path Yb of the current value ImA of the input signal does not exceed the reference value constant HisMax at every current value increase and decrease step, It can be determined that the top surface is not caught. In addition, if the absolute value of the data difference between the forward path Ya and the backward path Yb of the current value ImA of the input signal becomes greater than or equal to the constant HisMax of the reference value at each current value increase / decrease step, the start catch or top catch Can be determined.

  8A and 8B are diagrams showing the relationship of the MTF value with respect to the input current value to the drive unit of the AF lens unit 1 in FIG. 1, where FIG. 8A is a normal diagram and FIG. FIG. 4C is a diagram showing the top surface catching symptom 2.

  As described above, in the first embodiment, the measurement sensor 3 as an imaging sensor disposed to face one side of the AF lens unit 1 and the reference chart 4 disposed to face the other side of the AF lens unit 1. The MTF for the input current value from the AF drive control circuit 7 to the AF lens unit 1 based on the AF drive control circuit 7 for controlling the AF drive of the AF drive device 1b and the image data of the reference chart 4 from the measurement sensor 3. And an MTF calculation device 6 that performs a characteristic inspection of the displacement amount of the drive unit of the AF drive device 1b with respect to an input current value to the AF drive device 1b.

  Thus, the frequency of MTF calculation when inspecting the return path start hook (starting hook 14) is the same as the MTF value calculation and the frequency of MTF calculation when the forward path start hook (starting hook 13) is inspected. By setting it lower than that, the MTF resolution inspection of the lens and the driving hook inspection can be performed by the same inspection apparatus as the characteristic inspection of the AF driving apparatus 1b for the forward path and the backward path. The inspection frequency is changed in the INF and macro areas. The frequency of MTF calculation is changed in INF inspection and macro inspection. In this case, it is not necessary to change the chart during the inspection by corresponding to the INF position and the macro position by calculating with the MTF calculating device 6 by changing the inspection frequency. In this way, by performing the lens characteristic inspection and the AF driving device 1b characteristic simultaneously with one inspection apparatus, it is possible to save the space of the line, shorten the inspection time, and reduce the investment cost.

  Although not particularly described in the first embodiment, the characteristics of the displacement amount of the driving unit during the movement of the imaging lens and the displacement amount of the driving unit of the AF driving device during the forward movement and the movement of the driving unit during the backward movement are not particularly described. By changing the frequency of MTF calculation at the time of inspection, the MTF value for the input current value to the AF lens unit is calculated to inspect the resolution of the imaging lens, and the AF drive device for the input current value to the AF drive device If there is a characteristic inspection means for inspecting the displacement amount of the drive unit, the MTF characteristic inspection of the lens and the characteristics of the AF drive device (relationship between applied current and drive amount) can be performed simultaneously by one inspection device. Thus, the object of the present invention can be achieved, which can greatly reduce the inspection man-hours.

  Although not particularly described in the first embodiment, the camera-equipped mobile phone device, the smartphone, and the like, in which the AF lens unit 1 of FIG. 1 is mounted on a camera module and the camera module is used as an image input unit as an image input unit. It can be set as electronic information equipment, such as a personal computer with a camera.

  Although not particularly described in the first embodiment, FIG. 11 shows the relationship between the spatial frequency (LP / mm) and the MTF of the lens. In FIG. 11, the MTF of the lens is generally in the direction of decreasing the MTF value as the lens when the spatial frequency (LP / mm) increases. In other words, it can be seen that if the spatial frequency (LP / mm) is decreased, the MTF value of the lens increases.

  As mentioned above, although this invention has been illustrated using preferable Embodiment 1 of this invention, this invention should not be limited and limited to this Embodiment 1. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range from the description of the specific preferred embodiment 1 of the present invention based on the description of the present invention and the common general technical knowledge. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The present invention relates to a characteristic inspection apparatus and characteristic inspection method for an AF lens unit for inspecting optical characteristics of a lens and driving characteristics of a lens driving apparatus, and a characteristic inspection apparatus and characteristic for an AF camera module using the characteristic inspection apparatus for the AF lens unit. An inspection method, an AF lens unit having a lens unit and an AF drive unit for driving the lens unit, and an AF camera module using the AF lens unit as an image input device for an imaging unit, such as a digital video camera and a digital still camera In the field of electronic information equipment such as cameras, surveillance cameras and other image input cameras, scanner devices, facsimile devices, television telephone devices, and camera-equipped mobile phone devices, when testing the characteristics of the displacement of the drive unit during the backward movement During the inspection of the resolution of the imaging lens By setting the frequency of the MTF calculation lower than that at the time of the characteristic inspection of the displacement amount of the driving unit in the lens, the MTF characteristic inspection of the imaging lens and the characteristic of the AF driving device (the relationship between the applied current and the driving amount) are one inspection device. This can be done at the same time, greatly reducing the inspection man-hours.

DESCRIPTION OF SYMBOLS 1 AF lens unit 1a Lens 1b AF drive device 2 Measurement lens 3 Measurement sensor 4 Reference chart 5 Light source 6 MTF arithmetic unit 7 AF drive control circuit 11 High frequency ideal curve 12 Outward start catching curve (outward start catching characteristic)
13 Low frequency ideal curve 14 Return path start catch curve (return start start catch characteristic)
21 Ideal curve 22 Outward start catching curve (outward start catching characteristic)
23 Return path start hook curve (Return path start hook characteristic)

Claims (17)

In an AF lens unit characteristic inspection device having an imaging lens and an AF driving device for moving the imaging lens back and forth in the forward path and the backward path to adjust the focus.
The frequency of MTF calculation is changed between the resolution inspection of the imaging lens and the characteristic inspection of the displacement of the driving unit of the AF driving device in the forward movement and the characteristic inspection of the displacement of the driving unit in the backward movement. Thus, the MTF value for the input current value to the AF lens unit is calculated to check the resolution of the imaging lens, and the displacement amount characteristic of the driving unit of the AF driving device with respect to the input current value to the AF driving device A characteristic inspection device for an AF lens unit having characteristic inspection means for performing inspection.   The frequency of MTF calculation is set lower during the characteristic inspection of the displacement amount of the driving unit in the backward movement than in the characteristic inspection of the displacement amount of the driving unit in the forward movement and the inspection of the resolution of the imaging lens. The AF lens unit characteristic inspection apparatus according to claim 1, wherein the characteristic inspection of the displacement amount of the driving unit with respect to the input current value to the AF driving apparatus is performed simultaneously with the inspection of the resolution of the imaging lens.   2. The AF lens unit characteristic inspection apparatus according to claim 1, wherein the MTF calculation frequency is set lower in the MTF characteristic macro area than in the MTF characteristic INF area. 3.   2. The AF lens unit characteristic inspection apparatus according to claim 1, wherein the characteristic inspection of the displacement amount of the drive unit is performed based on presence / absence of at least one of a forward start catching characteristic and a backward start catching characteristic of the drive unit.   The characteristic inspection means includes an imaging sensor arranged to face one side of the AF lens unit, a reference chart arranged to face the other side of the AF lens unit, and AF driving of the AF driving device. An AF drive control circuit to be controlled, and an MTF value for the input current value is calculated based on image data of the reference chart from the imaging sensor corresponding to the input current value from the AF drive control circuit to the AF drive device The AF lens unit characteristic inspection apparatus according to claim 1, further comprising: an MTF arithmetic unit that performs characteristic inspection of a displacement amount of a driving unit of the AF driving apparatus with respect to the input current value.   6. The AF lens unit characteristic inspection apparatus according to claim 5, wherein the reference chart is printed with slits or edges, and is arranged at a sensor position when the AF lens unit is incorporated in a camera module.   The imaging sensor includes a solid-state imaging device in which a plurality of light-receiving units that photoelectrically convert image light from the reference chart to form an image and a plurality of light-receiving units of the solid-state imaging device. The AF lens unit characteristic inspection apparatus according to claim 5, further comprising: a signal processing unit that performs predetermined signal processing on the signal to obtain a series of image data.   The MTF arithmetic unit calculates an MTF value for the input current value based on image data from the imaging sensor corresponding to the input current value from the AF drive control circuit to obtain an MTF peak value, and the MTF peak The AF lens unit characteristic inspection apparatus according to claim 5, wherein the quality of the lens characteristic resolution is determined by comparing the value with a predetermined reference value. The MTF arithmetic unit detects the presence / absence of at least one of the forward path start catch characteristic and the backward path start catch characteristic of the drive unit of the AF drive unit, and detects the forward path start catch characteristic and the backward path start trigger characteristic. 6. The AF lens unit characteristic inspection apparatus according to claim 5 , wherein the characteristic inspection of the displacement amount of the driving unit of the AF driving apparatus is performed using a predetermined magnitude of the engagement characteristic as a threshold value.   When inspecting the resolution of the imaging lens based on the MTF value and inspecting the forward start catching characteristic, in order to narrow the peak width of the MTF value, the frequency of the MTF calculation is set to 80 to 200 LP / mm, and the return start triggering is performed. 2. The AF lens unit characteristic inspection apparatus according to claim 1, wherein the frequency of MTF calculation is set to 5 to 20 LP / mm in order to widen the peak width of the MTF value during characteristic inspection. In the AF lens unit characteristic inspection method provided with an AF driving device for moving the imaging lens back and forth in the forward path and the backward path to adjust the focus,
The frequency of MTF calculation is changed between the resolution inspection of the imaging lens and the characteristic inspection of the displacement of the driving unit of the AF driving device in the forward movement and the characteristic inspection of the displacement of the driving unit in the backward movement. Thus, the characteristic inspection means calculates the MTF value for the input current value to the AF lens unit to inspect the resolution of the imaging lens, and drives the AF drive device to the input current value to the AF drive device. A characteristic inspection method for an AF lens unit having a characteristic inspection step for inspecting the characteristic of the amount of displacement.   In the characteristic inspection step, the MTF calculation is performed at the time of the characteristic inspection of the displacement amount of the drive unit in the backward movement than at the time of the inspection of the resolution of the imaging lens and the characteristic inspection of the displacement amount of the driving part in the forward movement. The AF lens according to claim 11, wherein a characteristic inspection of a displacement amount of the driving unit with respect to an input current value to the AF driving device is simultaneously performed when the resolution of the imaging lens is inspected by setting the frequency of the imaging lens to be low. Unit characteristic inspection method.   The AF lens unit characteristic inspection method according to claim 11, wherein the frequency of MTF calculation is set lower in the macro area of the MTF characteristic than in the INF area of the MTF characteristic.   The AF lens unit characteristic inspection method according to claim 11, wherein the characteristic inspection of the displacement amount of the driving unit is performed based on presence / absence of at least one of a forward start catching characteristic and a backward start catching characteristic of the drive part.   When inspecting the resolution of the imaging lens based on the MTF value and inspecting the forward start catching characteristic, in order to narrow the peak width of the MTF value, the frequency of the MTF calculation is set to 80 to 200 LP / mm, and the return start triggering is performed. 12. The characteristic inspection method for an AF lens unit according to claim 11, wherein the frequency of MTF calculation is set to 5 to 20 LP / mm in order to widen the peak width of the MTF value during characteristic inspection.   A control program in which a processing procedure for causing a computer to execute the steps of the characteristic inspection method for an AF lens unit according to any one of claims 11 to 15 is described. A computer-readable readable storage medium in which the control program according to claim 16 is stored.