JP2008014827A - Method and device for adjusting lens's decentration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the decentration of a lens easily and with high accuracy. <P>SOLUTION: A first lens group G1 is held at an initial position by a section 13 for moving a lens to be adjusted. In such a state, a focusing adjustment chart 19 is photographed an image area sensor 22. Photographing of the focusing adjustment chart 19 is performed by changing the focusing position. The photographic screen of the focusing adjustment chart 19 is divided into 64 pieces of small divided areas of 8×8. An AF evaluation value is determined by each small divided area. The focusing position of a maximum AF evaluation value is determined by each divided area, made of adjacent small divided areas. A difference between the divided areas located at both ends in the right-and-left direction, in the photographic screen and a difference between the divided areas at both ends in the vertical directions in the photographic screen. Based on this differences, a decentration movement amount for reducing the differences is determined. Based on the decentration movement amount determined, the first lens group G1 of the lens unit 18 is moved from the initial position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens eccentricity adjusting method and apparatus used when assembling a lens of a camera or other optical equipment.

  The zoom lens includes, for example, a front lens group, a zoom lens body, a rear lens group, a focus lens, and the like, and is attached to a lens barrel. Among these, the zoom lens main body, the rear group lens, and the focus lens are assembled to the lens barrel so that their optical axes substantially coincide. The front lens group is attached to the lens barrel in a plane perpendicular to the optical axis by a spring-like ring, etc., and is fixed to the lens barrel with an adhesive after adjusting the eccentricity of the lens. The temporary attachment is made, and then the main attachment is performed if necessary.

  In the lens eccentricity adjustment, a resolution chart is taken with a CCD camera using a zoom lens, and the front group lens is moved in a plane orthogonal to the optical axis while an operator observes the taken chart image. Then, the front lens group is fixed to the lens barrel at a position where the chart image is resolved.

  However, in this method, the movement of the lens is adjusted by visual observation by the operator, skill is required for determination of resolution, there is no suitability for mass production, and there are individual differences in the adjustment results. There are problems such as poor.

  On the other hand, in Patent Document 1, the adjusted lens system is held in the optical path of the fixed lens system, a chart having a linear pattern in two directions is arranged in the optical path, and the two directions pass through the adjusted lens system and the fixed lens system. Is projected on the sensor, the illuminance distribution of the two projected linear chart images is detected in each of the two directions, the amount of coma flare centered on the strongest illuminance point is calculated, and the calculated amount of coma flare is obtained. The lens system to be adjusted is moved and adjusted based on the decentration correction amount to adjust the optical axis of the lens system. Thereby, the optical axis adjustment can be automatically performed at high speed.

Japanese Patent Laid-Open No. 2004-26883 discloses that by adjusting the inclination of the fixed group of the zoom lens, one blur (partial focus shift phenomenon occurring in the periphery of the image) near the tele end and near the wide end is eliminated. Objective. Then, the imaging state at four or more measurement points in the imaging plane is measured, the defocus coordinates where the imaging state is the best for each measurement point are specified, and the imaging state at each measurement point is Fixed in the case where four or more planes determined by three points of the best defocus coordinates are defined and the four or more planes are matched by adjusting the inclination of the fixed groups 1 and 3 with respect to the optical axis. The inclination amounts of the groups 1 and 3 are calculated, and the inclinations of the fixed groups 1 and 3 are adjusted using the calculated inclination amounts of the fixed groups 1 and 3 as target points.
JP 2000-121901 A JP 2003-43328 A

  However, in the case of Patent Document 1, since the eccentricity adjustment is performed based on the chart in the vicinity of the center, there is a problem that the adjustment accuracy with respect to the one-side blur at the peripheral portion is low. In addition, in the case of Patent Document 2, there are two adjustment points and a complicated calculation is required. Therefore, if the number of measurement points increases, the amount of calculation increases dramatically, and quick calculation becomes difficult. There's a problem. For this reason, since the number of measurement points cannot be increased, there is a problem that adjustment accuracy cannot be increased.

  The present invention has been made to solve the above-described problems, and provides a lens eccentricity adjustment method and apparatus that can easily and accurately adjust the lens eccentricity. Objective.

  In order to achieve the above-mentioned object, the present invention moves a lens to be adjusted in a two-dimensional direction on a lens mounting surface orthogonal to the optical axis, and adjusts the eccentricity of the lens to be adjusted with respect to the optical axis. In the adjustment method, the first adjustment step of holding the lens to be adjusted and moving the lens to be adjusted to the initial position on the lens mounting surface, and using the lens to be adjusted and the image sensor after the initial position movement, The focus adjustment chart is shot while changing the focus position, the shooting screen is divided into a plurality of top and bottom and left and right, a focus position measuring step for obtaining the focus position in each divided area, and each divided area of the shooting screen An eccentric movement amount calculating step for calculating an eccentric movement amount of the lens to be adjusted with respect to the optical axis so that the in-focus positions are aligned, and based on the calculated eccentric movement amount, And a second moving step of moving the integer lens.

  The eccentricity movement amount calculating step includes the difference between the focus positions of the divided areas located at both ends in the left-right direction of the shooting screen, and the focus positions of the divided areas positioned at both ends of the shooting screen in the vertical direction. Based on the difference, the amount of decentration movement of the lens to be adjusted with respect to the optical axis is calculated. Further, the difference between the in-focus positions of the divided areas located at both ends in the left-right direction of the shooting screen is added, and the eccentric movement amount in the left-right direction of the shooting screen is calculated by multiplying the added one by a coefficient, A difference between in-focus positions of divided areas located at both ends in the vertical direction of the shooting screen is added, and an eccentricity movement amount in the vertical direction of the shooting screen is calculated by multiplying the added value by a coefficient. And Further, the divided area is constituted by a set of a plurality of adjacent subdivided areas, and an average value of in-focus positions of the aggregated subdivided areas is set as a focused position in each divided area. .

  In the present invention, after the adjusted lens is moved from the initial position by the second movement step based on the calculated eccentric movement amount, the focus position measurement step and the eccentric movement amount calculation step are performed again. And a notification step of notifying that the eccentric adjustment of the lens to be adjusted has been completed when the calculated amount of eccentric movement is within a predetermined value.

  In the present invention, after the adjusted lens is moved from the initial position by the second movement step based on the calculated eccentric movement amount, the focus position measurement step and the eccentric movement amount calculation step are performed again. And a notification step of issuing an alarm when the obtained eccentric movement amount exceeds a predetermined value.

  A fixed lens system, a lens barrel to which the fixed lens system is assembled, and a lens mounting surface on which the lens to be adjusted is held so as to be movable in a two-dimensional direction perpendicular to the optical axis of the fixed lens system. It is preferable to adjust the eccentricity of the lens to be adjusted with respect to the photographic lens provided. The photographing lens is a zoom lens, and the in-focus position measuring step and the eccentric movement amount calculating step are performed at each of the tele end and the wide end of the zoom lens, and the tele end eccentric movement amount and the wide end are calculated. It is preferable to have a step of calculating a total eccentric movement amount by calculating an end eccentric movement amount and weighting the tele end eccentric movement amount and the wide end eccentric movement amount to obtain a total eccentric movement amount.

  The present invention is also a lens eccentricity adjusting device for adjusting the eccentricity of the lens to be adjusted with respect to the optical axis by moving the lens to be adjusted in a two-dimensional direction on a lens mounting surface orthogonal to the optical axis. An adjusted lens moving unit that holds the adjusted lens and moves the adjusted lens to an initial position and an arbitrary position on the lens mounting surface; and the adjusted lens moving unit moves the adjusted lens to the initial position. And moving the image of the focus adjustment chart by the shooting unit up, down, left and right using the lens to be adjusted and the image sensor. The focus position measuring unit for obtaining a focus position in each divided area, and the adjusted position with respect to the optical axis so as to align the focus position in each divided area of the shooting screen An eccentric movement amount calculating unit for calculating the eccentric movement amount of the lens, and a control unit for controlling the adjusted lens moving unit based on the calculated eccentric movement amount to move the adjusted lens from the initial position. It is characterized by having.

  According to the present invention, the lens to be adjusted is held, the lens to be adjusted is moved to the initial position on the lens mounting surface, and the focal position is changed using the lens to be adjusted and the image sensor after the initial position is moved. Shoot the focus adjustment chart, divide this shooting screen into multiple parts vertically and horizontally, find the focus position in each divided area, and align the focus position in each divided area of the shooting screen with respect to the optical axis By calculating the decentering movement amount of the lens to be adjusted and moving the lens to be adjusted from the initial position based on the decentering movement amount, the decentering adjustment of the lens can be performed easily and easily. On the other hand, manual adjustment requires a certain period of adjustment learning, and the productivity at the initial stage of production is low and the quality is not stable. This makes it possible to adjust the eccentricity and improve productivity.

  The calculation of the eccentric movement amount is based on the difference between the focus positions of the divided areas located at both ends in the left-right direction of the shooting screen and the difference between the focus positions of the divided areas positioned at both ends in the vertical direction of the shooting screen. Based on this, by calculating the eccentric movement amount of the lens to be adjusted with respect to the optical axis, even if the in-focus position is obtained for each divided area, it is possible to cope with simple calculations, and the eccentric movement amount can be obtained quickly and easily. be able to.

  In particular, the difference between the focus positions of the divided areas located at both ends of the shooting screen in the left-right direction is added, and the added amount is multiplied by a coefficient to calculate the amount of eccentric movement in the left-right direction of the shooting screen, Calculate by calculating the amount of eccentric movement in the vertical direction of the shooting screen by adding the difference in focus position between the divided areas located at both ends in the vertical direction of the shooting screen and multiplying this added value by a coefficient. The load is reduced, and the amount of eccentric movement can be determined more quickly and easily.

  Further, at each of the telephoto end and the wide end of the zoom lens, a focusing position measuring step and an eccentricity moving amount calculating step are performed to obtain the telephoto end eccentricity moving amount and the wide end eccentricity moving amount. By calculating the total eccentric movement amount by weighting the end eccentric movement amount and the wide end eccentric movement amount, the optimal eccentric position for each of the tele end and wide end is set to an intermediate position from the beginning. The eccentricity can be adjusted. Further, by using a photographic lens in which the imaging element is fixed to the lens barrel, the eccentricity adjustment is performed with the imaging element attached, so that the tilt adjustment of the imaging element becomes unnecessary.

  As shown in FIG. 1, the lens eccentricity adjusting device 10 of the present invention includes a lens holding base 11, a camera driving unit 12, an adjusted lens moving unit 13, a controller 14, an operation panel 15, and an alarm 16. . A mount portion 17 is formed on the lens holding base 11, and a lens unit 18 to be adjusted for eccentricity is set via the mount portion 17. Further, a camera driving unit 12, an adjusted lens moving unit 13, and a controller 14 are arranged in the lens holding table 11. A focus adjustment chart 19 is set in front of the lens unit 18. The focus adjustment chart 19 is illuminated substantially uniformly by the illumination device 20 as necessary.

  The lens unit 18 includes a zoom lens 21, an image area sensor 22, a zooming mechanism 23, an AF mechanism 24, a unit controller 26 having an image processing unit 25, and a battery (not shown) provided integrally with the zoom lens 21. I have.

  As shown in FIG. 2, the lens unit 18 is detachably attached to the camera body 30 to constitute a digital camera 31. The camera body 30 includes an operation panel 32, a release button 33, a liquid crystal panel 34 for displaying captured images and various setting items, a zooming button 35, a data recording unit for recording image data on a removable recording medium, a camera controller, A battery or the like (not shown) is provided.

  As shown in FIG. 1, the zoom lens 21 includes a lens barrel 41, first to fourth lens groups G <b> 1 to G <b> 4 and first to fourth lens groups G <b> 1 to G <b> 4 that constitute a photographic lens, respectively. To 44. The first lens group G1 and the third lens group G3 are fixed to the lens barrel 40 via lens holders 41 and 43. Note that the eccentricity adjusting method of the present invention is performed before fixing the first lens group G1. A second lens group G2, a third lens group G3, and a fourth lens group G4 are sequentially arranged on the image plane side of the first lens group G1.

  The first lens group G1 is a front group lens, the second lens group G2 is a zooming lens, the third lens group G3 is a rear group lens, and the fourth lens group G4 is a focus lens. The second lens group G2 and the fourth lens group G4 are held by lens holders 42 and 44 so as to be movable in the optical axis direction. The lens holders 42 and 44 mesh with guide rods 46 and 47 made of screw rods. The focus is adjusted by rotating the guide rod 46 by the stepping motor of the AF mechanism 24, and zooming is performed by rotating the guide rod 47 by the stepping motor of the zooming mechanism 23. Note that any or all of the lens groups G1 to G4 may be single lenses.

  The second to fourth lens groups G2 to G4 are fixed by being assembled to the lens holders 42 to 44 of the lens barrel 40. The first lens group G1 is urged so as to be pressed against the lens mounting surface 40a of the lens barrel 40 by a spring member (not shown) after being held by the lens holder 41, and in a two-dimensional direction on the lens mounting surface 40a. Can be moved to. Then, as will be described later, the lens holder 41 is temporarily attached to the lens mounting surface 40a with an adhesive or the like after the eccentricity is adjusted by the eccentricity adjusting method of the present invention, and is subsequently attached.

  An image area sensor 22 made of a CCD is disposed on the image plane side of the fourth lens group G4. The image area sensor 22 photoelectrically converts an image formed on the sensor surface by the zoom lens 21 to obtain an image signal. This image signal is processed by the image processing unit 25 to become digitized RAW data, which is temporarily stored in the SDRAM in the image processing unit 25. As shown in FIG. 2, when a camera body 30 is connected to the lens unit 18 and functions as a digital camera 31, RAW data in the SDRAM is read at an appropriate timing, and a controller on the camera body 30 side is read. After the image processing is performed, the image is displayed on the liquid crystal panel 34. Further, by operating the release button 33, the image data of the subject image displayed on the liquid crystal panel 34 is stored in the recording medium.

  As shown in FIG. 1, the adjusted lens moving unit 13 holds the first lens group G1 of the zoom lens 21 set on the lens holding base 11, and uses the held first lens group G1 as the light of the zoom lens 21. It is moved in a two-dimensional direction on the lens mounting surface 40a orthogonal to the axis L. For this reason, the lens clamp 50, the X direction shift part 51, the Y direction shift part 52, the Z direction shift part 53, and the base part 54 are provided. The lens clamp 50 is displaced between a holding position where the lens holder 41 of the first lens group G1 is held and an open position where it is opened.

  The X-direction shift unit 51 moves the first lens group G1 through the lens clamp 50 and the Y-direction shift unit 51 in a direction perpendicular to the optical axis (Z-axis direction) L and perpendicular to the paper surface of FIG. The Y-direction shift unit 52 moves the first lens group G1 perpendicular to the optical axis L via the lens clamp 50 in the Y direction. The Z-direction shift unit 53 moves the first lens group G1 in the optical axis L direction. Then, the X-direction shift unit 51 and the Y-direction shift unit 52 move the first lens group G1 along the lens mounting surface 40a on the XY plane to perform eccentricity adjustment. Further, the Z-direction shift unit 53 moves the first lens group G1 so that the first lens group G1 is slightly separated from the lens mounting surface 40a during the eccentricity adjustment.

  The camera drive unit 12 controls the zooming mechanism 23, the AF mechanism 24, and the image processing unit 25 via the unit controller 26 of the lens unit 18 based on the control signal from the controller 14, and adjusts the eccentricity of the first lens group G1. I do. Hereinafter, the eccentricity adjustment processing by the controller 14 and the camera drive unit 12 will be described with reference to the flowchart of FIG. This eccentricity adjustment processing is performed by software by a program, and an in-focus position measurement unit 61, an eccentricity movement amount calculation unit 62, and a determination unit 63 are formed in the controller 14.

  First, when the lens unit 18 to be adjusted is attached to the lens holding base 11, the camera driving unit 12 is connected to each part of the lens unit 18 via the mount unit 17. Next, when the adjustment start button on the operation panel 15 is pressed, the adjusted lens moving unit 13 holds the lens holder 41 of the first lens group G1 and then moves the first lens group G1 to the initial position that is the design position. Moving. Further, the second lens group G2, which is a zooming lens, is moved in the optical axis direction via the camera driving unit 12, and the zoom lens 21 is set at the telephoto end.

  Next, the calculation process of the eccentric movement amount on the tele end side is started. First, step feed of the fourth lens group G4 which is a focus lens is performed, and the focus adjustment chart 19 (see FIG. 1) is photographed at the focus lens position for each step feed. As shown in FIG. 4, the focus adjustment chart 19 only needs to be able to confirm the focus in each part of the shooting area PA. For example, black and white striped patterns are alternately arranged vertically and horizontally. Is used. The photographing data of the focus adjustment chart 19 is taken into the memory 14a in the controller 14.

  The controller 14 divides the photographing area PA of the focus adjustment chart at the time of each step feeding into 8 × 8 64-divided subdivision areas a1,1 to a8,8, and subdivides each subdivision area a1,1 to a8,8 An AF evaluation value is obtained. The AF evaluation value is, for example, a contrast value.

  Next, a set of a plurality of adjacent small divided areas is set as a divided area, and an AF evaluation value is obtained for each divided area. This is because if the AF evaluation values of the small divided areas are used as they are, variations in focus are picked up, and it is difficult to perform accurate eccentric adjustment.

  In the present embodiment, a divided area is configured by four adjacent subdivided areas. For example, out of 64 subdivision areas a1,1 to a8,8, the contrast values of a2,2, a2,3, a3,2, a3,3 are integrated, and this integrated value is AF of the first divided area A1. The evaluation value. Similarly, the AF evaluation value of the second divided area A2 is obtained using a2,4, a2,5, a3,4, a3,5. Thereafter, AF evaluation values for the third to ninth divided areas A3 to A9 are obtained in the same manner.

  Next, the feed pulse position at which the AF evaluation value is maximum for the first to ninth divided areas A1 to A9 is obtained as the focal positions F1 to F9 of the divided areas A1 to A9.

  FIG. 5 shows an example in which the focus positions F1, F5, and F9 are shifted in the divided areas A1, A5, and A9. The vertical axis represents the contrast value as the AF evaluation value, and the horizontal axis represents the contrast value. The feed pulse amount (position in the optical axis direction) of the focus lens is shown.

  Next, after obtaining the difference between the upper and lower ends of the focal positions F1 to F9 of the divided areas A1 to A9, these are added. Similarly, after obtaining the difference between the left and right ends of the focal positions F1 to F9 of the divided areas A1 to A9, these are added. Then, the eccentric movement amount is calculated by multiplying these difference addition values by the coefficients α and β. Instead of adding the difference, the eccentric movement amount may be obtained by using a difference average value obtained by dividing the sum of the differences by the added number.

That is, the X-direction eccentric movement amount x and the Y-direction eccentric movement amount y are obtained based on the following formulas (1) and (2).
x = α × {(F1−F3) + (F4−F6) + (F7−F9)} (1)
y = [beta] * {(F1-F7) + (F2-F8) + (F3-F9)} (2)

  The coefficients α and β are obtained in advance for each model of the zoom lens 21. Specifically, since the shift amount of the focal position with respect to the lens movement amount can be calculated by the lens design simulation, the coefficients α and β are obtained from the values. Also, the lens is moved quantitatively using several samples, the focal position is actually measured, and based on the actual movement amount and feed pulse amount (focal position), these movement amount and feed pulse amount match. Thus, the coefficients α and β are determined.

  Next, an example of how to determine the coefficients α and β will be described. First, the first lens group G1 is moved in units of several tens of μm in the + X direction from the mechanical center position, an autofocus operation is performed at this position, and the focal position is measured. Further, the first lens group G1 is moved in units of several tens of μm in the + X direction, and the focal position is measured in the same manner. Hereinafter, by repeating this movement every several tens of μm and measuring the focal position, five or more measurement points are taken in the + X direction, and five or more measurement points are taken in the minus X direction in the same manner. Then, an approximate straight line of the change amount of the pulse value with respect to the lens movement amount is obtained. The reciprocal of the slope of the approximate straight line is defined as a coefficient α. At this time, it is preferable to employ the average value of the reciprocal of the slope of the approximate line using several samples. For the coefficient β, the same operation as described above is performed in the Y direction to obtain the reciprocal of the slope of the approximate straight line, which is set as the coefficient β.

  Each eccentric movement amount x, y at the tele end is attached with a subscript t, and each eccentric movement amount x, y at the wide end is attached with a subscript w. Further, in order to distinguish the eccentric movement amount obtained in the first time and the eccentric movement amount obtained in the second time, the subscript 1 or the subscript 2 is attached to each eccentric movement amount. By the above formulas (1) and (2), the eccentric movement amount xt1 in the tele side x direction and the eccentric movement amount yt1 in the tele side y direction are obtained.

  Next, the second lens group (zooming lens) G2 is moved in the optical axis direction via the camera drive unit 12, and the zoom lens 21 is set at the wide end. Then, the calculation process of the eccentric movement amounts x and y on the wide end side is started. First, step feed of the fourth lens group (focus lens) G4 is performed, and the focus adjustment chart 19 is photographed at the focus lens position for each step feed. This photographing data is taken into the memory 14 a in the controller 14. The controller 14 calculates the wide end side eccentric movement amounts xw1, yw1 in the same manner as the tele end side eccentric movement amounts xt1, yt1 based on the focus adjustment chart photographing data at the time of each step feed. To do.

Next, as shown in FIG. 6, based on the obtained eccentric movement amounts xt1, yt1, xw1, and yw1, target positions xp1 and yp1 that are actually moved are weighted by the following equations (3) and (4). Obtained using the values nt1 and nw1.
xp1 = {(nt1 * xw1) + (nw1 * xt1)} / (nw1 + nt1)} (3)
yp1 = {(nt1 * yw1) + (nw1 * yt1)} / (nw1 + nt1)} (4)

  The weighting ratio nw1: nt1 uses a value determined in advance according to the type of zoom lens. Specifically, the lens is moved quantitatively using several samples, the focal position is actually measured at the tele end and wide end, and these movements are based on the actual movement amount and feed pulse amount (focal position). The weighting ratio nw1: nt1 is determined so that the amount and the feed pulse amount coincide.

  Hereinafter, an example of a method for determining the weighting ratio nw1: nt1 will be described. First, the zoom lens 21 is set at the telephoto end. Next, the X-direction shift unit 51 and the Y-direction shift unit 52 of the adjusted lens moving unit 13 shown in FIG. 1 move the first lens group G1 on the XY plane in units of 20 μm, for example, and this moving point (measurement point). Difference addition value FH [= {(F1-F3) + (F4-F6) + (F7-F9)}] in the X direction of the feed pulse amount at the time of autofocusing and difference addition value FV [= {in the Y direction (F1-F7) + (F2-F8) + (F3-F9)}] is obtained, and a total difference addition value FHV (= FH + FV) obtained by adding FH and FV is obtained. Measurement points where the added value FHV is 5 or less are represented by “x”, measurement points exceeding 5 and 10 or less are represented by “Δ”, and measurement points exceeding 10 and 20 or less are represented by “□”. When these measurement points of the same symbol are made continuous, the difference addition value FHV is an area AT1 where the difference addition value FHV is 5 or less, an area AT2 where the difference addition value FHV exceeds 5 and less than 10, and the difference addition value FHV exceeds 10 and 20 A tele-side difference addition value distribution diagram (see FIG. 7A) having the following region AT3 is obtained. Next, the zoom lens 21 is set at the wide end, and a wide difference addition value distribution diagram (see FIG. 7B) is obtained by the same operation as that at the tele end.

  By the way, the performance evaluation of the lens is not based on whether or not the difference addition value of the feed pulse amount is small, but a picture for performance evaluation called a chart is photographed, for example, contrast values are measured at several spatial frequencies, and each predetermined value is measured. This is done by confirming that the value has been exceeded. In the automatic image quality inspection process, the performance evaluation is automatically executed on a photographed image to determine whether it is OK (good) or NG (bad). This automatic inspection process for image quality is performed in a software manner by a program, and an automatic inspection process unit 64 for image quality is formed in the controller 14. This automatic image quality inspection processing unit 64 automatically determines whether or not the lens decentering adjustment result of the present invention has been properly achieved.

  At the same time as obtaining the data of the above difference addition value distribution map, the automatic image quality inspection is carried out, and it is determined whether it is OK or NG. As shown in FIG. 8, a tele-side OK area AGT and a wide-side OK area AGW consisting of measurement points for image quality inspection OK are obtained.

  As can be seen from FIGS. 7 and 8, the centers of the OK regions AGT and AGW and the centers of the regions AT1 and AW1 where the difference addition value of the amount of feed pulses is minimized substantially coincide with each other. Is different. For lens adjustment, the lens center may be positioned at a portion where the OK areas AGT and AGW at the tele end and the wide end overlap, and preferably the lens center is positioned near the center of the OK area. Therefore, the weighting ratio nw1: nt1 is determined so that the adjustment position comes near the center of the OK areas AGT and AGW.

There is a slight difference between the calculated value and the actual ideal position because individual differences in manufacturing occur in the lens. To make up for this difference, a second adjustment is performed. First, the eccentric movement amounts xt2, yt2, xw2, and yw2 are obtained in the same manner as the first adjustment while the first lens group G1 is held at the first adjustment position. Based on the eccentric movement amounts xt2, yt2, xw2, and yw2, target positions xp2 and yp2 that are actually moved are obtained by the following formulas (5) and (6) using the weighted intermediate values nt2 and nw2.
xp2 = {(nt2 * xw2) + (nw2 * xt2)} / (nw2 + nt2)} (5)
yp2 = {(nt2 * yw2) + (nw2 * yt2)} / (nw2 + nt2)} (6)

  Since the ideal position is approached by the first adjustment, as shown in FIG. 9, the actual movement amount L2 for the second time (movement from the first target position xp1, yp1 to the second target position xp2, yp2). The amount) is a sufficiently small numerical value compared to the first actual movement amount L1 (movement amount from the initial position (0, 0) to the first target position xp1, yp1). Then, the movement amount L2 is compared with the determination value K. When the movement amount L2 is equal to or less than K, it is determined that the adjustment is completed, and the adjustment completion / temporary display is performed. Thus, by performing the second adjustment, proper eccentricity adjustment is performed even when the number of data in the initial stage of production is small.

  Further, when the second movement amount L2 is not a small numerical value and is larger than the determination value K, it is determined that the adjustment is poor and the product is rejected. In this case, the alarm 16 gives an alarm of poor adjustment. With this alarm, the operator stores the first lens group G1 as a defective product in a location different from the completed product after the eccentricity adjustment without temporarily attaching the first lens group G1 to the lens barrel 40. Note that the second adjustment may be omitted, and the adjustment process may be completed with only the first movement amount L1.

  In the above-described embodiment, the contrast value is used as the AF evaluation value. However, any AF evaluation value may be used as long as AF evaluation is possible. Further, the coefficients α and β when the eccentric movement amounts are obtained at the tele end and the wide end are obtained separately. This is because the change in the focus position differs greatly between the tele end and the wide end with respect to the movement amount of the lens.

  In the above embodiment, the eccentricity adjustment of the lens unit 18 in which the image area sensor 22 is integrated with the zoom lens 21 has been described. However, the present invention is applied to a zoom lens in which the image area sensor 22 is provided separately. May be. In this case, an image area sensor is provided on the lens holder 11 and the focusing adjustment chart 19 is photographed. Further, the present invention may be implemented for a lens of a general digital camera in which the image area sensor 22 is provided on the camera body side. In this case, based on the image data of the focus adjustment chart obtained from the image area sensor attached to the camera body, the eccentric movement amount is obtained and the eccentric adjustment is performed in the same manner as in the above embodiment.

  In the above embodiment, the eccentricity adjustment of the front lens group of the zoom lens 21 has been described. However, the present invention may be implemented not only for the zoom lens 21 but also for the eccentricity adjustment of a single focus lens. Further, although the divided area is a 3 × 3 matrix arrangement, the present invention is not limited to this, and the present invention can be implemented with other matrix arrangements. Further, instead of the matrix arrangement, the eccentric movement amount may be obtained by the calculation formula of the eccentric movement amount based on the difference data in both end areas in a plurality of radiation directions passing through the central area. Further, the calculation of the eccentricity movement amount is not limited to twice, and may be performed once or three times or more.

It is the schematic which shows the eccentric adjustment apparatus of the lens of this invention. It is a perspective view which shows the digital camera of the state which attached the lens unit to the camera body. It is a flowchart which shows the eccentric adjustment method of the lens of this invention. It is explanatory drawing which shows the subdivision area which divided the picked-up image of the focus adjustment chart, and the subdivision area which consists of a some adjacent subdivision area. The vertical axis represents the contrast value as the AF evaluation value, and the horizontal axis represents the feed pulse amount of the focus lens, showing an example of the shift of the contrast value for each divided area. 10 is a graph showing a method for calculating target positions xp1, yp1 using tele-side eccentric movement amounts xt1, yt1, wide-side eccentric movement amounts xw1, yw1, and weighted intermediate values nt1, nw1. It is for demonstrating the method of calculating | requiring the weighting ratio nw1: nt1 for target position calculation, (A) shows the difference addition value distribution map of the amount of transmission pulses of the tele side, (B) is the difference addition value of the wide side A distribution chart is shown. FIG. 7 is a distribution diagram showing an OK area composed of measurement points of an OK result in image quality inspection processing, (A) shows a distribution map of a tele-side OK area, and (B) shows a distribution map of a wide-side OK area. It is a graph showing a method for calculating target positions xp2, yp2 using the second tele-side eccentric movement amounts xt2, yt2, wide-side eccentric movement amounts xw2, yw2, and weighted intermediate values nt2, nw2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Eccentricity adjustment apparatus 11 Lens holding stand 12 Camera drive part 13 Adjusted lens moving part 14 Controller 15 Operation panel 18 Lens unit 19 Focus adjustment chart 21 Zoom lens 22 Image area sensor 23 Zooming mechanism 24 AF mechanism 25 Image processing part

Claims (18)

In the lens eccentricity adjustment method, the lens to be adjusted is moved in a two-dimensional direction on the lens mounting surface orthogonal to the optical axis, and the eccentricity of the lens to be adjusted with respect to the optical axis is adjusted.
A first moving step of holding the lens to be adjusted and moving the lens to be adjusted to an initial position on the lens mounting surface;
After moving the initial position, the focus adjustment chart is shot while changing the focal position using the lens to be adjusted and the image sensor, and this shooting screen is divided into a plurality of vertical and horizontal directions, and the focus position in each divided area is determined. A focus position measurement process to be obtained,
An eccentricity movement amount calculating step of calculating an eccentricity movement amount of the lens to be adjusted with respect to the optical axis so as to align in-focus positions in each divided area of the photographing screen;
And a second moving step of moving the lens to be adjusted from the initial position based on the calculated amount of decentering movement.   The eccentricity movement amount calculating step includes a difference between in-focus positions between divided areas located at both ends in the left-right direction of the shooting screen and a difference between in-focus positions between divided areas located at both ends in the up-down direction of the shooting screen. The lens eccentricity adjustment method according to claim 1, further comprising: calculating an eccentric movement amount of the lens to be adjusted with respect to the optical axis. Add the difference of the in-focus position between the divided areas located at both ends of the left and right direction of the shooting screen, calculate the amount of eccentric movement in the left and right direction of the shooting screen by multiplying this added by a coefficient,
A difference between in-focus positions of divided areas located at both ends in the vertical direction of the shooting screen is added, and an eccentricity movement amount in the vertical direction of the shooting screen is calculated by multiplying the added value by a coefficient. The method for adjusting the eccentricity of a lens according to claim 2.   The divided area is constituted by a set of a plurality of adjacent subdivided areas, and an addition value of a focus position of the set subdivided areas is set as a focus position in each divided area. The method for adjusting the eccentricity of a lens according to any one of claims 1 to 3.   After moving the lens to be adjusted from the initial position in the second movement step based on the calculated eccentric movement amount, the focus position measurement step and the eccentric movement amount calculation step are performed again, and the obtained deviation is obtained. The lens eccentricity adjustment according to any one of claims 1 to 4, further comprising a notifying step for notifying that the eccentricity adjustment of the lens to be adjusted has been completed when the center movement amount is within a predetermined value. Method.   After moving the lens to be adjusted from the initial position in the second movement step based on the calculated eccentric movement amount, the focus position measurement step and the eccentric movement amount calculation step are performed again, and the obtained deviation is obtained. 6. The method for adjusting the eccentricity of a lens according to claim 1, further comprising a notifying step for generating an alarm when the amount of movement of the core exceeds a predetermined value.   An imaging device comprising: a fixed lens system; a lens barrel to which the fixed lens system is assembled; and a lens mounting surface on which the lens to be adjusted is held so as to be movable in a two-dimensional direction perpendicular to the optical axis of the fixed lens system The lens eccentricity adjustment method according to any one of claims 1 to 6, wherein an eccentricity adjustment of the lens to be adjusted is performed on the lens.   The lens eccentricity adjustment method according to claim 7, wherein the imaging element is fixed to the lens barrel.   The photographing lens is a zoom lens, and at each of the tele end and the wide end of the zoom lens, the in-focus position measurement step and the eccentric movement amount calculation step are performed, and the tele end eccentric movement amount and the wide end deviation are calculated. 8. A total eccentric movement amount calculating step for obtaining a total eccentric movement amount by calculating a center movement amount and weighting the tele end eccentric movement amount and the wide end eccentric movement amount. Or the decentering adjustment method of the lens according to 8. In the lens eccentricity adjusting device for adjusting the eccentricity of the lens to be adjusted with respect to the optical axis by moving the lens to be adjusted in a two-dimensional direction on the lens mounting surface orthogonal to the optical axis,
An adjusted lens moving unit that holds the adjusted lens and moves the adjusted lens to an initial position and an arbitrary position on the lens mounting surface;
An imaging unit that captures a focus adjustment chart while changing a focal position using the adjusted lens and an image sensor after moving the adjusted lens to the initial position by the adjusted lens moving unit;
A focusing position measurement unit that divides the shooting screen of the focusing adjustment chart by the shooting unit into a plurality of top and bottom and left and right, and obtains a focus position in each divided area;
An eccentricity movement amount calculation unit that calculates an eccentricity movement amount of the lens to be adjusted with respect to the optical axis so as to align in-focus positions in each divided area of the shooting screen;
A lens decentering adjustment apparatus, comprising: a control unit that controls the lens moving unit to be adjusted based on the calculated decentering movement amount and moves the lens to be adjusted from the initial position.   The eccentricity movement amount calculation unit includes a difference between in-focus positions between divided areas located at both ends in the left-right direction of the shooting screen and a difference between in-focus positions between divided areas located at both ends in the up-down direction of the shooting screen. The lens decentering adjustment apparatus according to claim 10, wherein an amount of decentering movement of the lens to be adjusted with respect to the optical axis is calculated on the basis of.   The eccentricity movement amount calculation unit adds a difference between in-focus positions of divided areas located at both ends in the left-right direction of the shooting screen, and multiplies the added value by a coefficient to deviate in the left-right direction of the shooting screen. Calculate the center movement amount, add the difference in focus position between the divided areas located at both ends of the shooting screen in the vertical direction, and multiply the added value by a coefficient to move the eccentricity in the vertical direction of the shooting screen The lens eccentricity adjusting device according to claim 11, wherein the amount is calculated.   The divided area is constituted by a set of a plurality of adjacent subdivided areas, and an addition value of a focus position of the set subdivided areas is set as a focus position in each divided area. The lens eccentricity adjusting device according to any one of 10 to 12.   After the adjusted lens moving unit moves the adjusted lens from the initial position based on the calculated eccentricity moving amount, the imaging unit, the focusing position measuring unit, and the eccentric moving amount calculating unit again. And an informing unit for performing in-focus position measurement and decentration movement amount calculation, and notifying that the decentering adjustment of the lens to be adjusted has been completed when the obtained decentration movement amount is within a predetermined value. The lens eccentricity adjusting device according to any one of claims 10 to 13.   After the adjusted lens moving unit moves the adjusted lens from the initial position based on the calculated eccentricity moving amount, the imaging unit, the focusing position measuring unit, and the eccentric moving amount calculating unit again. 15. The lens deflection according to claim 14, wherein when the in-focus position measurement and the eccentric movement amount are calculated and the obtained eccentric movement amount exceeds a predetermined value, the notification unit issues an alarm. Center adjustment device.   An imaging device comprising: a fixed lens system; a lens barrel to which the fixed lens system is assembled; and a lens mounting surface on which the lens to be adjusted is held so as to be movable in a two-dimensional direction perpendicular to the optical axis of the fixed lens system The lens eccentricity adjusting device according to any one of claims 10 to 15, wherein an eccentricity adjustment of the lens to be adjusted is performed on the lens.   The lens eccentricity adjusting device according to claim 16, wherein the imaging element is fixed to the lens barrel.   The photographing lens is a zoom lens, and at each of the tele end and the wide end of the zoom lens, the in-focus position measurement step and the eccentric movement amount calculation step are performed, and the tele end eccentric movement amount and the wide end deviation are calculated. 17. A total eccentric movement amount calculation unit that calculates a center movement amount and calculates a total eccentric movement amount by weighting the tele end eccentric movement amount and the wide end eccentric movement amount. Or the lens eccentricity adjusting device according to 17.

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