JP4699714B2 - Eccentricity measuring apparatus and eccentricity measuring method - Google Patents

Description

  The present invention relates to an eccentricity measuring device and an eccentricity measuring method for measuring the eccentricity of a spherical lens or an aspherical lens, a lens mold adjusted using the eccentricity measuring device or the eccentricity measuring method, and a lens The present invention relates to an imaging module having a lens manufactured using a mold.

Recently, aspherical lenses have been used to reduce aberrations or reduce the number of lenses.
For example, in digital cameras, the number of pixels is increasing, and it is required to reduce aberrations, and to reduce the number of lenses for miniaturization. For this reason, aspheric lenses are frequently used in digital cameras.
In addition, an imaging module provided in a mobile communication terminal such as a camera-equipped mobile phone is required to be downsized, and more than 1 million pixels are used as pixels. For this reason, an aspheric lens is used.
An aspherical lens is also used for a pickup lens for optical reading of a recording medium such as a DVD in order to improve reading accuracy.

Various apparatuses and methods for measuring the shape of such an aspheric lens have been proposed (see Patent Document 1 and Patent Document 2).
The eccentricity measuring apparatus of Patent Document 1 includes a lens receiving portion that holds a test lens, a rotating lens support member that is configured to freely rotate the lens receiving portion, and a test lens with respect to a rotation axis of the rotating lens support member. A paraxial eccentricity measurement unit that detects the eccentricity and direction of the center of paraxial curvature on both sides, a test surface shape measurement unit (displacement sensor unit) that detects the shape of the test surface, and a rotation angle of the test lens A rotation angle measuring unit. Furthermore, the decentration measuring device of Patent Document 1 compares the data obtained by rotating the lens to be measured and measuring the surface shape measuring unit with the design formula of the surface to be tested, and the difference between the two is the smallest. Calculate the relative shift amount and tilt amount, calculate the position of the surface apex with respect to the rotation axis from the shift amount and tilt amount, and calculate the position of the surface apex and the proximity of both surfaces of the test lens measured by the paraxial eccentricity measurement unit. And an arithmetic unit that calculates an inclination amount and direction of the aspherical axis with respect to the optical axis of the lens to be tested from the eccentric amount and direction of the center of curvature of the axis.

  In addition, the aspherical eccentricity measuring apparatus disclosed in Patent Document 2 includes a holding unit that holds a lens, a rotating unit that rotates the lens held by the holding unit, and a spot that detects the locus of a spot of light reflected from the lens. The trajectory detection means, the annular area shape data acquisition means for acquiring the shape data of the annular area of the test surface of the lens, the shape data of the annular area and the input shape data of the test surface are compared. And a processing unit for acquiring the position of the surface top. This processing unit acquires the eccentric amount and eccentric direction of the paraxial curvature center of the test surface from the spot trajectory, and the aspheric eccentricity of the test surface from the position of the surface and the eccentric amount and eccentric direction of the paraxial curvature center. The quantity and the aspheric eccentric direction are acquired.

Also, at present, when an aspheric lens is used, the accuracy required to obtain a predetermined performance is unknown. For this reason, even when an aspherical lens is used as a single lens, fine adjustment of the optical axis or the like is necessary.
In particular, in the case of a combined lens having an aspheric lens, each lens is combined, and the combination having the best optical characteristics such as aberration is selected and assembled. Furthermore, the angle in the plane orthogonal to the optical axis of the lens is also examined. Finally, the optical axis of the combined lens is adjusted.

Here, FIGS. 11A and 11B are schematic views showing a mold for manufacturing a lens, respectively.
As shown in FIGS. 11A and 11B, the first mold 200 and the second mold 204 are for producing four lenses from one mold. The lenses produced by the first mold 200 and the second mold 204 are combined to form a combined lens.
As shown in FIG. 11A, the first mold 200 is formed with first to fourth cavities 202a, 202b, 202c, 202d. The second mold 204 is formed with first to fourth cavities 206a, 206b, 206c, and 206d.
Each lens manufactured by the first cavity 202a to the fourth cavity 202d of the first mold 200 and each of the lenses manufactured by the first cavity 204a to the fourth cavity 202d of the second mold 204. In combination with a lens, the optical characteristics such as aberration are examined. Then, find the combination with the best optical characteristics. Next, for the best combination, the lens is rotated around the optical axis to find an angle with better optical characteristics.
In this manner, the combination of the lenses produced by the first mold and the second mold and the assembly direction are determined.

JP 2003-156405 A JP 2004-28672 A

In Patent Document 1 and Patent Document 2, the amount of eccentricity of the lens is measured by comparing the data obtained by rotating the lens with the design formula of the lens. However, the eccentricity measuring devices of Patent Document 1 and Patent Document 2 have a problem that the measurement accuracy is 5 μm and sufficient accuracy cannot be obtained.
In Patent Document 1 and Patent Document 2, there is a problem that although an aspherical shape can be measured, a spherical surface cannot be measured.

In addition, when a combined lens is used for the imaging module, it is necessary to select a combination of lenses constituting the combined lens, and it is also necessary to specify the direction of the lens for assembly. Thus, in order to obtain a product of a certain quality or more, it is necessary to select a combination of lenses, and there is a problem that the manufacturing process of the imaging module becomes complicated. As a result, the manufacturing cost of the imaging module increases, and as a result, the cost of the product increases.
Furthermore, even when one aspheric lens is used in the imaging module, it is necessary to adjust the optical axis, etc., and when the lens optical axis adjustment work becomes complicated due to the downsizing of the lens, a predetermined optical system is used. There is a possibility that characteristics cannot be obtained.

Also in the lens mold, when the manufactured lens is used as a combined lens, it is necessary to make adjustments such as selecting a lens combination and further specifying the lens direction for assembly. In mass production, in order to maintain quality, it is necessary to examine lens combinations for all molds, and this work increases the cost of the lens.
Further, in a combined lens, even if lenses are combined, the optical characteristics are not always good.

  In addition, in a mold for producing an aspheric lens, there is a problem that a factor for reducing accuracy is unknown, and a factor for producing a highly accurate aspheric lens cannot be specified.

An object of the present invention is to provide an eccentricity measuring apparatus and an eccentricity measuring method capable of solving the problems based on the prior art and measuring the eccentricity of a lens with sufficient accuracy.
Another object of the present invention is to provide a lens mold capable of producing a lens that does not require adjustment even if it is a combined lens as well as a single lens.
Another object of the present invention is to provide an imaging module that can be easily assembled.

  In order to achieve the above object, a first aspect of the present invention is an eccentricity measuring device for measuring the eccentricity of a lens having a lens portion and a flange portion, the rotatable rotary table, and the rotary table. A table provided on the table and capable of moving in the horizontal direction and inclined with respect to the vertical direction, the table on which the lens is placed, the center of the lens unit provided above the table, and the rotation center of the rotary table A center position measurement unit that measures whether or not the lens unit is coincident, a first measurement unit that measures shake of the lens unit when the lens is rotated, and the flange when the lens is rotated A second measuring unit that measures angular eccentricity defined by the amount of displacement of the upper surface of the unit, and a flat surface defined by the amount of displacement of the outer peripheral surface of the flange when the lens is rotated. There is provided an eccentricity measuring apparatus characterized by a third measuring unit for measuring eccentricity.

  In the present invention, for example, at least one surface of the lens portion is constituted by an aspherical surface.

  A second aspect of the present invention is an eccentricity measuring method for measuring the eccentricity of a lens having a lens part and a flange part, wherein the lens is placed on a rotatable rotary table, and the rotary table The center of rotation of the lens unit and the center of the lens unit, and substantially rotating the lens unit when the rotary table is rotated, and rotating the rotary table to rotate the upper surface of the flange unit. And a step of measuring a parallel eccentricity defined by an amount of displacement of the outer peripheral surface of the flange portion, and an eccentricity measuring method characterized by comprising: .

  In the present invention, a step of measuring a first center position on the front surface side of the lens portion, a step of measuring a second center position on the back surface side of the lens portion, and an outer peripheral surface of the flange portion As a reference, it is preferable to include a step of measuring an interplane eccentricity defined by a deviation between the first center position and the second center position.

  According to a third aspect of the present invention, there is provided a lens mold for producing a lens having a lens portion and a flange portion, wherein the produced lens is obtained by the eccentricity measuring apparatus according to the first aspect of the present invention. Measured, the lens provides a lens mold characterized in that the angular eccentricity is 0.12 ° or less and the parallel eccentricity is 10 μm or less.

  According to a fourth aspect of the present invention, there is provided a lens mold for producing a lens having a lens portion and a flange portion, wherein the produced lens is obtained by the eccentricity measuring method according to the second aspect of the present invention. Measured, the lens provides a lens mold characterized in that the angular eccentricity is 0.12 ° or less and the parallel eccentricity is 10 μm or less.

  In the present invention, the decentering between the surfaces of the lens is preferably 10 μm or less.

  According to a fifth aspect of the present invention, there is provided an imaging module comprising a lens produced by the lens mold according to the third aspect or the fourth aspect of the present invention. .

  According to the eccentricity measuring apparatus of the present invention, there is a rotary table, a table provided on the rotary table, which can move in the horizontal direction and can be inclined with respect to the vertical direction, and on which the lens is placed, A center position measurement unit that is provided above the table and measures whether or not the center of the lens unit and the rotation center of the rotary table coincide with each other, and shake of the lens unit of the lens when the lens is rotated. A first measuring unit for measuring, a second measuring unit for measuring angular eccentricity defined by the amount of displacement of the upper surface of the flange portion of the lens unit when the lens is rotated, and a case of rotating the lens By providing a third measurement unit that measures parallel eccentricity defined by the amount of displacement of the peripheral surface of the flange portion of the lens unit, the center of the lens unit and the rotation center of the rotary table coincide with each other. In that state, the eccentricity of the lens is decomposed into each direction, can be measured as the angle eccentricity, and parallel decentration. In addition, since the center of rotation of the rotary table coincides, measurement can be performed with higher accuracy than before.

According to the eccentricity measuring method of the present invention, a lens is placed on a rotatable turntable, the rotation center of the turntable and the center of the lens unit are matched, and the turntable is rotated. The angular deviation defined by the amount of displacement of the upper surface of the flange portion of the lens portion is measured by substantially rotating the rotating table and rotating the rotary table, and by the amount of displacement of the outer peripheral surface of the flange portion of the lens portion. By measuring the prescribed parallel eccentricity, the eccentricity of the lens can be decomposed in each direction and easily measured as angular eccentricity and parallel eccentricity. In addition, since the center of rotation of the rotary table coincides, measurement can be performed with higher accuracy than before.
Further, a first center position on the surface side of the lens unit, and the lens portion of the second center position is measured at the back side of, based on the outer circumferential surface of the flange portion, the first center position and the second center It is also possible to measure the inter-surface eccentricity defined by the deviation from the position.

According to the lens mold of the present invention, since the eccentricity of the produced lens can be disassembled and measured in each direction, correction can be made according to the measurement result of the eccentricity, and finally A highly accurate lens can be produced. Therefore, a lens having excellent optical characteristics that do not require adjustment can be manufactured.
Furthermore, because it is possible to produce highly accurate lenses, even when applied to a combined lens that combines multiple lenses, a combined lens that has excellent optical characteristics without adjustments such as optimization of the combination of each lens Can be obtained.

  According to the imaging module of the present invention, it is possible to obtain a good image quality with little aberration.

Hereinafter, an eccentricity measuring apparatus, an eccentricity measuring method, a lens mold, and an imaging module according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic diagram showing an eccentricity measuring apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the eccentricity measuring apparatus 10 has a support column 14 erected on a base 12. The support column 14 is provided with a first arm 16 and a second arm 18. The first arm 16 and the second arm 18 are members that extend in a direction perpendicular to the direction in which the support column 14 extends, and are respectively movable in the vertical direction.

A rotating spindle 20 is provided on the base 12. A gonio stage 22 is provided on the rotary spindle 20. An XY stage 24 that can move in two orthogonal directions (X direction and Y direction) on a horizontal plane is provided on the gonio stage 22.
A test lens 60 is placed on the XY stage 24 via a jig 26.
The test lens 60 is, for example, an aspheric lens having a flange portion 62 (see FIG. 2) and a lens portion 64 (see FIG. 2).

In the eccentricity measuring apparatus 10 of the present embodiment, a first measuring device 30 for measuring the surface 64a (see FIG. 2) of the lens 60 to be examined is provided. The first measuring instrument 30 is movable according to the position of the lens 60 to be examined.
In addition, a second measuring device 32 that measures the upper surface 62a (see FIG. 2) of the flange portion of the lens 60 to be tested is provided at the distal end portion of the first arm 16. Furthermore, a third measuring instrument 34 for measuring the outer peripheral surface 62b (see FIG. 2) of the flange portion is provided at the distal end portion of the first arm 16.

In the present embodiment, the first measuring instrument 30 to the third measuring instrument 34 can all be the same.
As the first measuring device 30 to the third measuring device 34, for example, a laser focus displacement meter is used. Thereby, the 1st measuring device 30-the 3rd measuring device 34 can irradiate the measuring object with the laser beam b, and can measure it non-contactingly. The first measuring device 30 to the third measuring device 34 may be touch probe type displacement meters.

  The rotary spindle 20 rotates the test lens 60 in the rotation direction R. The rotary spindle 20 has, for example, a vertical axis as a rotation axis and can be rotated with high accuracy with respect to the rotation axis. The rotary spindle 20 is provided with a rotation driving means (not shown).

The goniostage 22 can tilt the lens 60 to be tested with respect to a center line C passing through the rotation axis of the rotary spindle 20 by an angle θ. The gonio stage 22 has a base portion 22a and a movable portion 22b. The base portion 22a is fixed to the rotary spindle 20, and the movable portion 22b is inclined at an angle θ with respect to the center line C. Thereby, the test lens 60 is inclined by the angle θ.
The gonio stage 22 is provided with driving means (not shown). The gonio stage 22 may be moved manually.

The XY stage 24 moves the test lens 60 in two directions orthogonal to each other on the horizontal plane. The XY stage 24 is not particularly limited as long as the test lens 60 can be moved on a horizontal plane, and a stage used in a known optical measuring instrument or the like can be used.
The XY stage 24 is provided with driving means (not shown). Further, the XY stage 24 may be moved manually. Thereby, the test lens 60 is moved in two directions orthogonal to each other on the horizontal plane.

  The jig 26 is for placing the test lens 60 on the XY stage 24. The jig 26 is constituted by, for example, a cylindrical member.

  Further, an eccentric microscope (center position measuring unit) 40 is provided above the rotary spindle 20. The eccentric microscope 40 measures whether or not the center of the lens 60 to be examined and the rotation center of the rotary spindle 20 coincide with each other.

The eccentric microscope 40 includes a light source 42, a first lens barrel 44, a half mirror 46, a second lens barrel 48, a detection unit 50, and a display device 52. A first lens barrel 44 is provided with an opening facing the rotary spindle 20. The first lens barrel 44 is fixed to the second arm 18.

In the first lens barrel 44, a light source 42 is provided in another opening on the side opposite to the rotating spindle 20 side. In the first lens barrel 44, a second lens barrel 48 extending in the horizontal direction is provided on the side surface in the vicinity of the light source 42. The second lens barrel 48 is provided with a detection unit 50 at the other end. A display device 52 is connected to the detection unit 50.
In addition, a half mirror 46 is provided in the first lens barrel 44 at an angle of 45 ° in the vicinity of the second lens barrel 48 connected thereto.

Light source 42 is for irradiating the measurement light L _m in the test lens 60.
The half mirror 46 is intended to be incident on the detection unit 50 provided with the reflected light L _R reflected by the sample lens 60 to the second lens barrel 48.

Detector 50 is for detecting the reflected light _{L R,} for example, CCD image sensor is used. In the present invention, the present invention is not limited to a CCD image sensor, and a CMOS image sensor can also be used.

Display device 52 is for displaying the position of the reflected light L _R obtained by the detector 50. The display device 52 allows the operator to determine whether or not the center of the lens 60 to be tested is coincident with the center of the rotary spindle 20. For example, when the center of the test lens 60 coincides with the center of the rotary spindle 20, the display is performed at the center of the display device 52.

The display device 52 is not particularly limited, and various monitors such as a CRT or an LCD (liquid crystal display panel) can be used. Further, the display device 52 may be connected to the first measuring device 30 to the third measuring device 34 to display the measurement result.
The rotary spindle 20, goniometer 22 and XY stage 24 used in this embodiment all have sufficiently small rotational accuracy and linear motion accuracy compared to the measurement accuracy of the eccentricity measuring apparatus 10 of this embodiment. Is.

Next, an eccentricity measuring method using the eccentricity measuring device 10 of the present embodiment will be described with reference to FIGS. 1 to 5A to 5C.
2 to 4 are schematic views showing the eccentricity measuring method of this embodiment in the order of steps.
As shown in FIG. 2, the test lens 60 has a flange portion 62 and a lens portion 64.

First, the test lens 60 is placed on the XY table 24 (see FIG. 1) via the jig 26 (see FIG. 1).
Next, the 1st measuring device 30 (refer FIG. 1) is arrange | positioned in the position which can measure the surface 64a of the lens part 64 of the lens 60 to be measured.

  Next, the rotation of the surface 64a is measured by the first measuring instrument 30 while rotating the rotating spindle 20 (see FIG. 1) and rotating the test lens 60. In this case, the surface 64a is shaken like the lens 60 to be measured represented by a broken line in FIG. Moreover, the measurement result by the 1st measurement part 30 becomes the curve F shown to Fig.5 (a). The deflection is δ at the maximum in one rotation (0 ° to 360 °).

  Next, with the eccentric microscope 40, it is measured whether the center of the lens 60 to be tested and the rotation center of the rotary spindle 20 coincide with each other. In this case, as shown in FIG. 2, the center of the test lens 60 and the rotation center of the rotary spindle 20 do not match.

  Next, the test lens 60 is moved using the XY stage 24 so that the center of the test lens 60 coincides with the rotation center of the rotary spindle 20 as shown in FIG. At this time, for example, the operator operates the XY stage 24 while looking at the display device 52 using the eccentric microscope 40.

Next, using a goniometer 22, to adjust the inclination of the lens 60, as shown by the curve _{A j} of FIG. 5 (a), 1 rotation of the surface 64a at (0 ° ~360 °) runout Set the maximum value to 1/10 or less of the measurement accuracy.
Thereby, as shown in FIG. 4, the test lens 60 is installed in a state where the center of the test lens 60 coincides with the rotation center of the rotary spindle 20 and the surface 64a is substantially free from vibration. The Thus, the lens 60 to be tested has the center of the lens 60 to be on the rotation center of the rotary spindle 20, and a surface orthogonal to the optical axis of the lens 60 (hereinafter referred to as a lens surface) is the surface of the XY stage 24. Parallel. Hereinafter, such a state is referred to as a “centering state”.
In the present invention, the state in which there is substantially no shake on the surface of the lens portion means that the shake is 1/10 or less of the measurement accuracy. In this case, if the measurement accuracy is 1 μm, the maximum value of the shake is 0.1 μm or less.

  After this centering state, the rotary spindle 20 (see FIG. 1) is rotated to rotate the lens 60 to be tested, and the second measuring device 32 causes the upper surface 62a of the flange portion 62 of the lens 60 to be tested. Measure the displacement. That is, the inclination of the lens surface of the test lens 60 is measured. The measurement results (0 ° to 360 °) are shown in FIG.

As shown in FIG. 5 (b), the maximum value A of the displacement amount of the upper surface 62a of the flange portion 62 is converted into an angle as shown below, whereby the lens surface of the lens 60 to be examined is converted. Tilt can be measured. Thus, the inclination of the lens surface of the test lens 60 defined by the amount of displacement of the upper surface 62a of the flange portion 62 of the test lens 60 is defined as an angle eccentricity E _a ( μm ).

Further, simultaneously with the angular eccentricity _{E a,} by the third measuring device 34 measures the displacement of the outer peripheral surface 62b of the flange portion 62. That is, the deviation of the center of the test lens 60 is measured. The measurement results (0 ° to 360 °) are shown in FIG.

As shown in FIG. 5C, the value B having the largest absolute value of the displacement amount of the outer peripheral surface 62 b of the flange portion 62 is set as the deviation of the center of the lens 60 to be tested. Thus, the deviation of the center of the lens 60 to be measured, which is defined by the amount of displacement of the outer peripheral surface 62b of the flange portion 62, is defined as a parallel eccentricity E _p (μm).

Further, eccentricity measuring apparatus 10 of the present embodiment, the angle eccentricity _{E a,} and in addition to the parallel decentration _{E p,} as shown in FIG. 6 (a) and (b), also interplanar eccentricity _{E f} Can be measured. Hereinafter, the inter-plane eccentricity E _f will be described.

  Similar to the aspheric lens 60 shown in FIG. 2, the aspheric lens 70 shown in FIG. 6A has a flange portion 72 and a lens portion 74. The lens unit 74 has a front surface 76 and a back surface 78. The lens unit 74 is a two-surface aspheric lens in which both the front surface 76 and the back surface 78 are aspheric surfaces.

In the aspherical lens 70 shown in FIG. 6A, the center (first center) position of the front surface 76 coincides with the center (second center) position of the back surface 78. In this case, the interplane eccentricity E _f = 0 (μm).

On the other hand, in the aspherical lens 70a shown in FIG. 6B, the center position of the front surface 76 and the center position of the back surface 78a do not match. That is, the center line C passing through the center of the surface 76, and the center line C _e passing through the center of the back surface 78 does not match. The center line C, the deviation between the _{C e} is the interplanar eccentricity _{E f.}

For example, an imaging module of a camera-equipped mobile phone uses a two-surface aspheric lens in order to reduce the number of lenses. As described above, when both surfaces are aspherical, if the inter-surface eccentricity E _f is large, predetermined optical characteristics cannot be obtained. Therefore, like the case of reducing the number of lenses, it is important to use a small lens surface-to-surface eccentricity E _f.

Next, a method for measuring the inter-plane eccentricity E _f of this embodiment will be described.
First, as shown in FIG. 7A, the aspheric lens 70 is mounted on the XY table 24 (see FIG. 1) via the jig 26 (see FIG. 1) with the surface 76 of the aspheric lens 70 facing up. Put.
Next, the center of the surface 76 and the rotation center of the rotary spindle 20 (see FIG. 1) are made to coincide. The method for matching the center of the surface 76 with the center of rotation of the rotary spindle 20 is the same as the method shown in FIG. 3, and a detailed description thereof will be omitted.
Next, the position of the outer peripheral surface 72a of the flange portion 72 is measured by the third measuring instrument 34 (see FIG. 1).

Next, as shown in FIG. 7B, the aspheric lens 70 is placed on the XY table 24 via the jig 26 with the back surface 78 of the aspheric lens 70 facing up.
Next, the center of the back surface 78 is aligned with the rotary spindle. The method of matching the center of the back surface 78 with the rotary spindle is the same as the method shown in FIG. 3, and detailed description thereof is omitted.

Next, the position of the outer peripheral surface 72a of the flange portion 72 is measured by the third measuring instrument 34 (see FIG. 1).
In the aspheric lens 70, the front surface 76 and the back surface 78 have a common flange portion 72. For this reason, the distance between the outer peripheral surface 72a of the flange portion 72 and the center of the front surface 76 is obtained by superimposing the measurement data of the center position of the front surface 76 and the central position of the rear surface 78 on the basis of the outer peripheral surface 72a of the flange portion 72. Further, from the distance between the outer peripheral surface 72a of the flange portion 72 and the center of the back surface 78, the deviation between the center of the front surface 76 and the center of the back surface 78, that is, the inter-surface eccentricity E _f can be obtained.

In the eccentricity measuring instrument 10 of the present embodiment, a rotating spindle 20 that rotates the test lens 60, a gonio table 22 that changes the inclination of the test lens 60, and an XY table 24 that changes the installation position of the test lens 60; And monitoring using the eccentric microscope 40 for measuring the center position of the lens 60 to be tested and the first measuring device 30 for measuring the shake of the surface 64a of the lens portion 64 of the lens 60 to be tested. The center of the detecting lens 60 and the rotation center of the rotary spindle 20 are made to coincide. In this state, the rotating spindle 20 is rotated to rotate the test lens 60, and the upper surface 62a and the outer peripheral surface 62b of the flange portion 62 of the test lens 60 are respectively measured with the second measuring instrument 32 and the third measuring instrument 32. by measuring at the measuring instrument 34, the eccentricity of the lens is decomposed into each direction, it is possible to measure the angle eccentricity E _a and parallel decentration E _p. In this case, since the center of the lens 60 to be tested and the center of rotation of the rotating spindle 20 coincide, measurement can be performed with higher accuracy than in the past.

Further, the inter-surface eccentricity E _f can be obtained by obtaining the center position and the position of the outer peripheral surface of the flange part for both surfaces of the lens part. Note that the inter-surface eccentricity E _f can also be measured with high accuracy because the center of the lens 60 to be tested and the rotation center of the rotary spindle 20 are matched using the eccentric microscope 40.

In the present embodiment, the measurement accuracy of the angular eccentricity _{E a} is less .00573 °. The measurement accuracy of the parallel decentration _{E p} and interplanar eccentricity _{E f} is 2μm or less. The measurement accuracy of the parallel decentration E _p and interplanar eccentricity E _f is preferably 1μm or less.
Here, when the lens center line is arranged in the vertical direction, the measurement accuracy of the angular eccentricity E _a is the amount of displacement of the lens center line in the horizontal direction (the amount of displacement of the upper surface 62a (see FIG. 4), absolute value). The largest value A (see FIG. 5B) is 1 μm or less with respect to a length of 10 mm of a vertical line extending in the vertical direction (hereinafter referred to as a vertical line).
When converting the maximum value of the measurement accuracy of the angular eccentricity _{E a} to the angle ^{θ, θ = tan -1 (1} (μm) / 10 (mm)) = tan -1 (1.0 × 10 -4) = 0 .00573 °. Therefore, the measurement accuracy of the angular eccentricity _{E a} is less .00573 ° if indicated by the angle theta.
Thus, by comparing angular eccentricity E _a in the test lens _60, and the measurement results of the parallel decentration E _p and interplanar eccentricity E _f, and optical characteristics of the lens 60, the angle eccentricity E _a , parallel decentration E _p and interplanar eccentricity E _f is able to know the effect on the optical properties such as aberration. Therefore, it is possible to know the accuracy necessary to obtain predetermined optical characteristics.

In the eccentricity measuring method of the present embodiment, the rotation center of the rotary spindle 20 and the center of the test lens 60 are made to coincide with each other, and the inclination of the test lens 60 is adjusted, and then the test lens 60 is moved. while rotating, by measuring the top surface and the side surface of the flange portion, the eccentricity of the lens is decomposed into each direction, it is possible to angle eccentricity E _a, and a parallel decentration E _p is measured. In addition, since the center of rotation of the rotary table coincides, measurement can be performed with higher accuracy than before.
Further, by obtaining the center of both surfaces of the lens unit, the inter-surface eccentricity E _f can be obtained.

As described above, in the eccentricity measuring method of the present embodiment, the rotation center of the rotary spindle 20 and the center of the test lens 60 are made to coincide with each other, and further, the inclination of the test lens is adjusted. high accuracy angular eccentricity _{E a,} it is possible to measure the parallel decentration _{E p} and interplanar eccentricity _{E f.}
Also in eccentricity measurement method of this embodiment, the angle eccentricity E _a in the test lens _60, and the measurement results of the parallel decentration E _p and interplanar eccentricity E _f, and optical characteristics of the lens 60 by comparison, the angle eccentricity E _a, parallel decentration E _p and interplanar eccentricity E _f is able to know the effect on the optical properties such as aberration. Therefore, it is possible to know the accuracy necessary to obtain predetermined optical characteristics.
Note that the eccentricity measuring apparatus 10 and the eccentricity measuring method of the present embodiment are not limited to the eccentricity measurement of an aspherical lens. For example, a spherical lens is measured in the same manner as an aspherical lens. Can do.

Next, a lens mold according to an embodiment of the present invention will be described.
FIG. 8A is a schematic cross-sectional view showing a lens mold according to an embodiment of the present invention, and FIG. 8B is an aspherical lens manufactured by the lens mold shown in FIG. FIG.

  As shown in FIG. 8A, the lens mold 80 basically includes a lower mold 82, an upper mold 84, a first insert 86, and a second insert 88. A line where the lower mold 82 and the upper mold 84 are combined is a parting line PL. With this lens mold 80, an aspheric lens 92 shown in FIG. This aspherical lens 92 also has a flange portion 94 and a lens portion 96.

  The lower mold 82 is formed with a first through hole 82a into which the first insert 86 is inserted. A recess 82b communicating with the first through hole 82a is formed on the parting line PL side of the lower mold 82. The recess 82b is for forming the flange portion 94 of the aspheric lens 92 to be manufactured.

  Further, the upper mold 84 is formed with a second through hole 84a at a position aligned with the first through hole 82a in the vertical direction. The first through hole 82a and the second through hole 84a are formed so that the center lines coincide with each other in the vertical direction. The second insert 88 is inserted into the second through hole 84a.

  In the lens mold 80 of this embodiment, the back surface 96 b of the aspherical lens 92 is formed by the first nest 86. Further, the surface 96 a of the aspherical lens 92 is formed by the second nest 88.

  As shown in FIG. 8A, the lower mold 82 and the upper mold 84 are combined, and the first insert 86 and the second insert 88 are respectively connected to the first through hole 82a and the second through hole 84a. The cavity 90 is formed by being inserted into the.

An aspherical lens 92 is formed by supplying a raw material such as glass or a transparent resin material to the area to be the cavity 90 and combining the lower mold 82 and the upper mold 84.
In the aspherical lens 92, the surface 96 a of the lens portion 96 is formed by the peripheral surface 88 a of the second insert 88. Further, the back surface 96 b of the lens portion 96 is formed by the convex surface 86 a of the first nest 86.

For the aspherical lens 92 shown in FIG. 8B, the angular eccentricity E _a , the parallel eccentricity E _p , and the inter-surface eccentricity are determined by the eccentricity measuring device 10 (see FIG. 1) or the eccentricity measuring method of the present invention. E _f is measured. Based on these measurement results, it is determined whether or not the lens mold 80 needs to be adjusted.
When the lens mold 80 needs to be adjusted, the lens mold 80 is selected in accordance with the measurement items (angle eccentricity E _a , parallel eccentricity E _p , and inter-plane eccentricity E _f ) that do not provide molding accuracy. Adjust.

Generally, the recess 82b is formed by electric discharge machining. For this reason, the recess 82b has a lower processing accuracy than the first insert 86, the second insert 88, the first through hole 82a, and the second through hole 84a. Therefore, when the molding accuracy of the flange portion 94 of the aspheric lens 92 is low, the concave portion 82b is corrected.
Further, when the accuracy of the inter-surface eccentricity E _f is low, the positioning accuracy between the lower die 82 and the upper die 84 is increased.
In this way, the aspherical lens 92 manufactured by the lens mold 80 is measured, and the lens mold 80 is corrected based on the measurement result, thereby manufacturing the aspherical lens 92 with high molding accuracy. be able to. Thereby, the aspherical lens 92 with excellent optical characteristics can be obtained. Therefore, the aspherical lens 92 produced by the lens mold 80 of the present embodiment exhibits predetermined optical characteristics without adjustment.

In the lens obtained by the lens mold of the present invention, the angular eccentricity E _a is the amount of displacement of the center line in the horizontal direction (the amount of displacement of the upper surface 62a (FIG. 4) when the center line of the lens is arranged in the vertical direction. The value A (see FIG. 5B)) having the largest absolute value is 20 μm or less with respect to the length of the vertical line of 10 mm. Incidentally, when converting the maximum value of the angle eccentricity _{E a} to the angle ^{θ, θ = tan -1 (20} (μm) / 10 (mm)) = a tan -1 (0.02) = 0.12 ° . Thus, the angle eccentricity _{E a} is 0.12 ° or less, if indicated by the angle theta.
Further, in the lens obtained by the lens mold of the present invention, parallel decentration E _p of the lens is at 10μm or less, preferably 5μm or less, more preferably 2μm or less. Furthermore, the inter-surface eccentricity E _f of the lens is 10 μm or less, preferably 5 μm or less, and more preferably 2 μm or less.
Parallel decentration _{E p} of the lens 10~20μm is the usual level of precision is. Further, the inter-surface eccentricity E _f of the lens is 10 to 20 μm, which is the current normal level accuracy.

In the lens mold of the present embodiment, when a plurality of the same lenses are formed from one mold, it is possible to increase the molding accuracy of the manufactured lens and to make the quality constant. For this reason, it is suitable for mass production.
In particular, in the case of a combination lens, it is not necessary to investigate an optimum combination of lenses as in the prior art, and a combination lens having predetermined optical characteristics can be obtained simply by combining them. That is, a lens that does not require special adjustment can be manufactured. For this reason, an assembly process of an imaging module or the like can be simplified, and productivity can be improved. Thereby, the manufacturing cost of the product in which the lens of the present invention is used, and the product cost can be lowered.

In addition, in a combined lens using a lens having a small aperture, predetermined optical characteristics can be obtained even when adjustment is not possible simply by assembling. For this reason, it can respond also to size reduction of an apparatus.
The lens mold 80 according to the present embodiment is not limited to the production of an aspheric lens. For example, a spherical lens having excellent optical characteristics is produced as in the case of an aspheric lens. Can do.

Hereinafter, an imaging module provided with an aspherical lens manufactured using the lens mold of the present invention will be described. In the aspheric lens provided in the imaging module, as described above, angular eccentricity E _a, when placing the center line of the lens in the vertical direction, the deviation amount in the horizontal direction of the center line (the amount of displacement of the upper surface 62a The value A (see FIG. 5B)) having the largest absolute value (see FIG. 4) is 20 μm or less with respect to the length of the vertical line of 10 mm. Incidentally, when converting the maximum value of the angle eccentricity _{E a} to the angle ^{θ, θ = tan -1 (20} (μm) / 10 (mm)) = a tan -1 (0.02) = 0.12 ° . Thus, the angle eccentricity _{E a} is 0.12 ° or less, if indicated by the angle theta.
Further, parallel decentration _{E p} of the lens is at 10μm or less, preferably 5μm or less, more preferably 2μm or less. Furthermore, the inter-surface eccentricity E _f of the lens is 10 μm or less, preferably 5 μm or less, and more preferably 2 μm or less.

FIG. 9 is a schematic cross-sectional side view showing the imaging module according to the embodiment of the present invention.
It is connected to the imaging module 100 shown in FIG. 9, an amplifier (not shown), and an A / D converter (not shown), and is used as an imaging unit for a mobile phone with a camera, a digital camera, and the like.
The amplifier amplifies the electric charge obtained by the imaging module 100 according to the object to be photographed. The A / D converter converts the electric charge obtained according to the object to be imaged amplified by the amplifier into a digital signal and outputs the digital signal to a memory or the like.

  The imaging module 100 converts light generated according to an object to be photographed into electric charges, and includes, for example, a CCD type image sensor or a CMOS type image sensor.

As shown in FIG. 9, the imaging module 100 according to the present embodiment basically includes an imaging unit 112, a lens barrel 102, and an aspheric lens 92.
In the imaging module 100, an imaging unit 112 is mounted on a surface 110 a of a flexible printed circuit board (hereinafter referred to as FPC) 110. A lens barrel 102 is provided so as to surround the imaging unit 112.
Moreover, the board | substrate 114 and FPC110 are connected by the mounting means of wire bonding or tab bonding, for example.

  The imaging unit 112 uses, for example, a CCD image sensor (hereinafter referred to as a CCD sensor). In the imaging unit 112, a light receiving region 116 in which light receiving units (not shown) made of, for example, photodiodes are arranged in a lattice shape is formed on a substrate 114. In addition, an amplifier and an A / D converter are formed on the substrate 114, and further, what is necessary for configuring a CCD such as a shift register is formed around the light receiving region 116. As described above, the imaging module 100 shown in FIG. 9 substantially represents an imaging unit.

A partition wall 118 is formed on the surface of the substrate 114 so as to surround the periphery of the light receiving region 116. A cover glass 120 is provided so as to cover the region surrounded by the partition wall 118. The light receiving region 116 is sealed by the cover glass 120.
Further, in the imaging unit 112, an infrared cut filter 124 is provided on the upper surface of the cover glass 120.

The lens barrel 102 has a cylindrical casing 104, and the casing 104 is closed at one end and opened at the other end. A flange portion 106 is provided along the peripheral surface of the other end of the housing 104. The flange portion 106 is formed of, for example, an annular thin plate whose outer shape is circular or square. The inner diameter of the housing 104 is large enough to accommodate the substrate 114, and the substrate 114 is accommodated in the opening 104a.
A through-hole 104c through which photographing light is incident is formed around the position corresponding to the central axis (not shown) of the housing 104 on the closing surface 104b on the one end side of the housing 104. In addition, an aspheric lens 92 is provided inside the housing 104 on one end side through a lens holder 108. Further, the flange portion 106 of the lens barrel 102 is provided in contact with the surface 110 a of the FPC 110.

A CCD sensor is used for the imaging unit 112. As a manufacturing method of this CCD sensor, for example, after forming a light receiving area corresponding to a number of CCD sensors on a silicon wafer, the silicon wafer is diced and cut out for each CCD sensor to form a rectangular chip. There is a method of manufacturing by forming a partition wall on a chip and then placing a cover glass on the partition wall to seal a light receiving region or the like.
In addition to this, as a manufacturing method of this CCD sensor, after forming light receiving areas corresponding to a number of CCD sensors on a silicon wafer, partition walls corresponding to each CCD sensor are formed in a grid pattern, for example. There is also a method of manufacturing by dicing so that the partition wall 118 is cut in half after covering all the CCD sensors and attaching a cover glass.

  In the imaging module 100 of the present embodiment, the aspherical lens 92 has excellent optical characteristics, so that it is possible to obtain a good image quality with little aberration. Further, as described above, the use of the aspheric lens 92 facilitates assembly. For this reason, the manufacturing cost of the imaging module 100, and hence the cost of the product can be reduced. Furthermore, in the imaging module 100, the assembled lens can be easily assembled instead of the aspherical lens 92, the manufacturing cost can be reduced, and the product cost can be reduced.

Further, by using the lens mold according to the present invention, an optical lens having excellent optical characteristics can be obtained even when the combined lens 130 formed by combining three lenses 132, 134, and 136 as shown in FIG. 10 is used as an imaging lens. Can do.
In the combined lens 130, the lenses 132, 134, 136 have flange portions 132a, 134a, 136a. These flange portions 132a, 134a, and 136a are fitted to each other to constitute the combined lens 130. Therefore, in the combined lens 130, the lenses 132, 134, and 136 require high molding accuracy for the flange portions 132a, 134a, and 136a. However, the lenses 132, 134, and 136 manufactured using the lens mold of the present invention have high molding accuracy.

The flange portion 132a of the lens 132 is fitted inside the flange portion 134a on one surface of the lens 134, the flange portion 136a of the lens 136 is fitted inside the flange portion 134a on the other surface of the lens 134, and the lenses 132 and 136 are fitted. By bringing the flange surfaces 132a and 136a of the flange portions 132a and 136a into contact with the lens 134 (flange surface viewed from the optical axis direction), a combined lens 130 including three lenses 132, 134 and 136 is obtained.
Here, since the lenses 132, 134, and 136 have high molding accuracy when the flange portions 132a, 134a, and 136a are properly fitted and assembled, the optical axes of the lenses 132, 134, and 136 coincide with each other.
That is, the assembled lens 130 is assembled by fitting the flange portions 132a, 134a, and 136a, so that the optical axes coincide with each other automatically without inter-lens decentering, and positioning in the optical axis direction of each other is also performed. It is. Therefore, according to this combination lens 130, it is possible to prevent decentering between lenses and to perform positioning in the optical axis direction without depending on the lens barrel.

  As described above, by using the lens mold of the present invention, even a combination lens of an aspherical lens can be obtained with high accuracy in which the optical axes coincide with each other without special adjustment. Further, since only the flange portion is fitted, the assembly process can be simplified, the productivity can be improved, and the manufacturing cost and thus the product cost can be reduced.

The present invention is basically as described above. As described above, the eccentricity measuring device, the eccentricity measuring method, the lens mold, and the imaging module of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and does not depart from the gist of the present invention. Of course, various improvements or modifications may be made.
In the present invention, the lens is not limited as long as it is spherical or aspherical and has a flange portion. For example, in the case of an aspheric lens, at least one surface may be an aspheric surface.

It is a schematic diagram which shows the eccentricity measuring apparatus which concerns on the Example of this invention. It is a schematic diagram which shows the eccentricity measuring method of a present Example in order of a process. It is a schematic diagram which shows the next process of FIG. It is a schematic diagram which shows the next process of FIG. (A) is a graph showing the measurement result of the deflection of the lens to be measured, taking the displacement amount on the vertical axis and the rotation angle of the rotary spindle on the horizontal axis, and (b) taking the displacement amount on the vertical axis, It is a graph which shows the measurement result of the upper surface of the flange part of a to-be-tested lens by taking the rotation angle of a rotation spindle on a horizontal axis, (c) is a displacement amount on a vertical axis | shaft, and shows the rotation angle of a rotation spindle on a horizontal axis. It is a graph which shows the measurement result of the outer peripheral surface of the flange part of a to-be-tested lens. (A) and (b) is a sectional view for explaining the definition of the surface-to-surface eccentricity E _f of the present invention. (A) and (b) are schematic sectional views showing a method of measuring the interplanar eccentricity E _f of the present invention in order of steps. (A) is typical sectional drawing which shows the lens metal mold | die which concerns on the Example of this invention, (b) is a side view which shows the aspherical lens produced with the metal mold | die shown to (a). It is. It is a typical sectional side view which shows the imaging | photography module which concerns on the Example of this invention. It is typical sectional drawing which shows the structure of a group lens. (A) And (b) is a schematic diagram which respectively shows the metal mold | die which manufactures a lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Eccentricity measuring apparatus 12 Base body 14 Support | pillar 16 1st arm 18 2nd arm 20 Rotating spindle 22 Goniometer stage 22a Base part 22b Movable part 24 XY stage 26 Jig 30 First measuring instrument 32 Second measuring instrument 34 Second 3 Measuring instrument 40 Eccentric microscope 42 Light source 44 First lens barrel 46 Half mirror 48 Second lens barrel 50 Detector 52 Display device 60 Lenses 62, 72, 94, 132a, 134a, 136a Flange 62a Upper surface 62b Peripheral surfaces 64, 74, 96 Lens portion 64a Surface 70, 92 Aspheric lens 76 Surface 78 Back surface 80 Lens mold 82 Lower mold 82a First through hole 84 Upper mold 84a Second through hole 86 First nesting 86a Convex surface 88 Second nesting 88a Circumferential surface 90, 202a to 202d, 204a to 204d Cavity T 100 Imaging module 102 Lens barrel 104 Case 108 Lens holder 110 Flexible printed circuit board (FPC)
DESCRIPTION OF SYMBOLS 112 Image pick-up part 114 Board | substrate 116 Light-receiving area 118 Partition 120 Cover glass 130 Pair lens 132,134,136 Lens 200,204 Mold

Claims (2)

An eccentricity measuring device for measuring angular eccentricity, parallel eccentricity, and inter-surface eccentricity of a lens having a lens portion and a flange portion, at least one surface of which is an aspheric surface,
A rotatable turntable,
A table provided on the rotary table, capable of moving in the horizontal direction and inclined with respect to the vertical direction, and the lens being placed thereon;
A center position measurement unit that is provided above the table and measures whether or not the center of the lens unit and the rotation center of the rotary table coincide with each other;
A first measurement unit that measures shake of the lens unit when the lens is rotated;
A second measuring unit that measures an angular eccentricity defined by the amount of displacement of the upper surface of the flange when the lens is rotated;
And measuring a parallel eccentricity defined by a displacement amount of the outer peripheral surface of the flange portion when the lens is rotated, and a third measuring unit for measuring a position of the outer peripheral surface of the flange portion,
The lens is mounted on the table with the flange portion supported by a cylindrical jig,
The rotation table is rotated, the first measurement unit measures the deflection of the lens unit, the center position measurement unit matches the center of the lens unit with the rotation center of the rotation table, and the and maximum deflection of the lens portion is the angle eccentricity measurement accuracy and the parallel decentration measuring accuracy of less than 1/10 of the case of rotating the rotary table, the state deflection of the lens portion is substantially free whether or not to measure,
When the center of the lens unit coincides with the rotation center of the rotary table and the rotary table is rotated, the deflection of the lens unit is relative to the measurement accuracy of the angular eccentricity and the measurement accuracy of the parallel eccentricity. when Te is in a state not the substantially rotates the said rotary table as it is, the angle eccentricity defined by the amount of displacement of the upper surface of the flange portion by the second measurement section, and the parallel decentration defined by displacement of the outer peripheral surface of the flange portion by the third measuring unit measures,
If the center of the lens unit does not coincide with the center of rotation of the rotary table, and the lens unit is shaken when the rotary table is rotated, the table is adjusted and the center of the lens unit is adjusted. When the rotation table coincides with the rotation center of the rotation table and the rotation table is rotated, the lens unit does not substantially shake with respect to the measurement accuracy of the angular eccentricity and the measurement accuracy of the parallel eccentricity. after the state, by rotating the rotary table, said angle eccentricity, and the outer periphery of the flange portion by the third measurement unit defined by the second measuring unit by the displacement amount of the upper surface of the flange portion with measuring the parallel decentration defined by displacement of the surfaces,
Further, when the lens is placed on the table with the front side of the lens unit facing up, the center of the lens unit is aligned with the rotation center of the rotary table, and the rotary table is rotated. and 1/10 or less of the measurement accuracy of the maximum value of the interplanar eccentricity of deflection of the lens portion, after the state substantially no vibration of the lens portion, the outer peripheral surface of the flange portion and the lens portion The distance from the first center position on the front surface side is measured by the third measurement unit, and then the lens is placed on the table with the back surface side of the lens unit facing up, and then the center of the lens unit And the rotation center of the rotary table coincide with each other, and when the rotary table is rotated, the deflection of the lens unit is substantially in the state with respect to the measurement accuracy of the inter-surface eccentricity , Of the flange The distance between the peripheral surface and the second center position on the back surface side of the lens portion is measured by the third measuring portion, and the first center position and the second center position are measured based on the outer peripheral surface of the flange portion. eccentricity measuring apparatus and measuring the eccentricity between the plane defined by the deviation of the center position. An eccentricity measuring method for measuring angular eccentricity, parallel eccentricity, and inter-surface eccentricity of a lens having a lens portion and a flange portion, at least one surface of which is an aspheric surface,
The flange portion of the lens is placed on a table provided on a rotatable rotary table that can move in the horizontal direction and can tilt with respect to the vertical direction, and is supported by a cylindrical jig. The center and the center of the lens unit coincide with each other, and the maximum value of the deflection of the lens unit when the rotary table is rotated is 1/10 of the measurement accuracy of the angular eccentricity and the measurement accuracy of the parallel eccentricity. The following, and the step of making the lens part substantially free of shake ,
Said rotary table is rotated, chromatic and measuring the parallel decentration defined by displacement of the outer peripheral surface of said angular eccentricity, and the flange portion is defined by the amount of displacement of the upper surface of the flange portion And
Furthermore, after placing the lens on the table with the surface side of the lens unit facing up, the center of the lens unit and the rotation center of the rotary table are matched, and the maximum value of the deflection of the lens unit is The measurement accuracy of the inter-surface eccentricity is 1/10 or less, and the lens portion is substantially free from shake, and in this state, the outer periphery of the flange portion and the first center on the surface side of the lens portion Measuring the distance to the position;
After the lens is placed on the table with the back surface side of the lens portion facing up, the center of the lens portion and the rotation center of the rotary table are matched, and the deflection of the lens portion is decentered between the surfaces. Measuring the distance between the outer peripheral surface of the flange portion and the second center position on the back surface side of the lens portion in the state where the measurement accuracy is substantially eliminated,
Relative to the outer peripheral surface of the flange portion, eccentricity measuring, characterized in that a step of measuring the eccentricity between the plane defined by the displacement between the second central position and the first center position Method.

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