JP6515927B2 - Method of manufacturing mold and method of manufacturing lens array - Google Patents

Description

  The present invention relates to a method of manufacturing a mold for molding a lens array and a method of manufacturing a lens array using such a mold.

  As a lens array processing method, prepare a work to be a mold, first process a portion corresponding to one central array element, measure eccentricity error and shape error with respect to the whole mold, and then, eccentricity There is one that corrects the processing data so that the error and the shape error become less than the allowable value, and processes the portion corresponding to all the other array elements with the corrected processing data (see Patent Document 1). Regarding this processing method, it is also described that warpage and contraction are corrected by measuring deformation due to warpage and contraction of an array-shaped element that is actually formed as a shape error and changing the infeed amount of the processing tool. .

  However, in the method described in Patent Document 1 above, the shape of the array-shaped element including the individual array elements is measured to measure the deviation from the ideal value, so a long time is required for the measurement, and It is not easy to maintain measurement accuracy until the end. In addition, it is not always easy to convert the deviation from the ideal value into the trajectory of the tool for each array element, and the time and labor from trial manufacture to obtaining a finished product may be enormous.

Japanese Patent Application Laid-Open No. 2007-276049

The present invention has been made in view of the problems of the above background art, and it is an object of the present invention to provide a method of manufacturing a mold for a lens array, which can be manufactured in a relatively short time by a simple method. Do.
Another object of the present invention is to provide a method of manufacturing a lens array using a mold obtained by the above-mentioned manufacturing method.

A first method of manufacturing a mold according to the present invention is a method of manufacturing a mold having a plurality of optical transfer surfaces for forming a lens array, the plurality of optical transfer surfaces based on an expression of an axially symmetric surface. The simulated mold is manufactured by processing the surface, and the expression of the non-axisymmetric surface of each optical transfer surface unit is calculated based on the error amount obtained by the measurement of the lens array molded by the simulated mold. The processing of the plurality of optical transfer surfaces of the mold is performed in units of each optical transfer surface based on the expression and the expression of the non-axisymmetric surface. Here, the expression is not limited to a general mathematical expression including a variable, an operation expression, etc., but includes a data table in which functional points are collected.

  In the above manufacturing method, the expression of the non-axisymmetric surface is calculated based on the amount of error obtained by the measurement of the lens array formed by the simulation mold, and the expression of the axisymmetric surface and the expression of the non-axisymmetric surface are calculated. Based on the processing of the plurality of optical transfer surfaces of the mold, the manufacture of the mold of the lens array having the plurality of optical surfaces of the axisymmetric type can be simplified. That is, since trial manufacture and measurement are performed from the viewpoint of dividing the surface shape of the lens array into the component of the axisymmetric surface and the component of the non-axisymmetric surface, the period from trial production of the lens array to obtaining a finished product is shortened. Effort can be reduced.

  According to a specific aspect of the present invention, in the above manufacturing method, the expression of the non-axisymmetric surface is an amount of deviation from a target value of an apex position through which the optical axis passes and an amount of deviation from a target aspheric shape. Is an expression expressed using at least one of

  According to another aspect of the present invention, the expression of the non-axisymmetric surface is an expression in which the amount of deviation of the vertex position of the optical transfer surface from the target value is defined by a free-form surface expression.

  According to another aspect of the present invention, the maximum compensation amount according to the expression of the non-axisymmetric surface is 10 μm. In this case, the amount of compensation associated with the non-axisymmetric surface is relatively small, and it is easy to relatively improve the shape accuracy of the mold.

A second method of manufacturing a mold according to the present invention is a method of manufacturing a mold having a plurality of optical transfer surfaces for molding a lens array, and a plurality of optical systems based on axisymmetric processing data which is a design value. A simulated mold is produced by processing the transfer surface, and the expression of the non-axisymmetric surface of each optical transfer surface unit is calculated based on the error amount obtained by the measurement of the lens array molded by the simulated mold, and the design value On the other hand, the expression of the axisymmetric surface is calculated by adding the correction amount obtained by the test processing, and the processing of the plurality of optical transfer surfaces of the mold is performed based on Is performed on each optical transfer surface unit .

  In the above manufacturing method, an expression of a non-axisymmetric surface is calculated based on the amount of error obtained by the measurement of the lens array molded by the simulation mold, and the axial symmetry is obtained by adding the correction amount obtained by test processing to the design value. Since a surface expression formula is calculated and a plurality of optical transfer surfaces of a forming die are processed based on the expression formula of the axisymmetric surface and the nonaxisymmetric surface, a plurality of optical surfaces of the axisymmetric type are provided The manufacture of the mold for the lens array can be simplified. In particular, since the expression of the axially symmetric surface is the design value plus the correction amount obtained by the test processing, the shape accuracy of the element lenses constituting the lens array can be enhanced.

  According to another aspect of the invention, the test process is performed on a material different from the material of the mold. In this case, it is easy to make test processing quick and inexpensive.

  According to another aspect of the present invention, the mold has, as the plurality of optical transfer surfaces, a plurality of types of optical transfer surfaces having different design values of the expression of the axially symmetric surface, and the expression of the axial symmetry surface is A plurality of correction amounts obtained by test processing are respectively added to a plurality of types of design values corresponding to a plurality of types of optical transfer surfaces. In this case, it is possible to cope with the case where the lens array includes multiple types of element lenses. A plurality of types of element lenses may have different corresponding wavelengths, different fields of view, or the like.

  According to another aspect of the present invention, the plurality of optical transfer surfaces have optical axes parallel to each other, and the plurality of optical transfer surfaces are processed by a tool having a rotational axis parallel to the optical axes. In this case, the shapes of the plurality of optical transfer surfaces to be processed on the mold by the tool can be easily aligned, and the processing accuracy can be easily improved.

  According to another aspect of the invention, the expression of the non-axisymmetric surface is a free-form surface equation, and the axisymmetric surface is an aspheric surface equation.

  The manufacturing method of the lens array which concerns on this invention has the process of shape | molding using the shaping | molding die obtained by the said manufacturing method.

  In the above manufacturing method, since molding is performed using the mold obtained by the above method of manufacturing a mold, manufacturing of a lens array provided with a plurality of optical surfaces of axisymmetric type can be simplified, and from trial manufacture of lens arrays The time to obtain a finished product can be shortened, and the effort can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates notionally a shaping | molding die apparatus provided with the shaping | molding die which concerns on embodiment. It is a perspective view explaining the shaping | molding die which concerns on embodiment, and its manufacturing process. 3A and 3B are a plan view and a side cross-sectional view for explaining a molded article produced by the molding die apparatus of FIG. It is a block diagram explaining a processing device of a forming die. It is a flowchart explaining the manufacturing method of a shaping | molding die. It is sectional drawing explaining the formation process of a lens array. 7A and 7B are diagrams for explaining the first correction amount set on the molding surface of the molding die. It is a perspective view explaining test processing by a dummy work.

  Hereinafter, with reference to the drawings, a method of manufacturing a mold according to an embodiment of the present invention will be specifically described.

  The forming apparatus 30 shown in FIG. 1 includes a pair of forming dies 31 and 32, and both forming dies 31 and 32 are relatively displaced in the AB direction parallel to the Z axis by the drive device 40. , 32 can be opened and closed. A mold space surrounded by molding surfaces 31t and 32t provided on both is formed by closing the molds 31 and 32 buttling the molten resin into the mold spaces, molding surfaces 31t and 32t. It is possible to obtain a molded article or a lens array having an outer shape corresponding to

The first mold 31 includes a core portion 31a forming a molding surface 31t and a peripheral portion 31b supporting the core portion 31a. On the end face on the first molding die 31 side of the core portion 31a, a large number of optical transfer surfaces 34a arranged in a matrix parallel to the XY plane, and a support portion transfer surface 34b formed around the optical transfer surface 34a And are formed (see FIG. 2). Each optical transfer surface 34a is an aspheric surface obtained by inverting the optical surface of the element lens constituting the lens array, and has an optical axis TX extending parallel to the Z axis. That is, the large number of optical transfer surfaces 34a arranged on the lattice points are the same or similar aspheric surfaces having the optical axis TX parallel to each other. The supporting portion transfer surface 34b has a slight level difference between the center side and the outer peripheral side, but the surfaces 43d and 43e are flat and extend parallel to the XY plane.
The core portion 31a is formed by using, for example, stainless steel, super steel, or another steel material as a base material, and the optical transfer surface 34a and the like are formed by finishing the surface of the NiP plated layer covering the base material. Furthermore, the entire surface of the core portion 31a can be coated with a release agent.
The end face of the peripheral portion 31 b is a parting surface PA 1 used when the first mold 31 is butted against the second mold 32.

The second mold 32 comprises a core portion 32a forming a molding surface 32t and a peripheral portion 32b supporting the core portion 32a. On the end face on the second molding die 32 side of the core portion 32a, a large number of optical transfer surfaces 35a arranged in a matrix parallel to the XY plane, and a support portion transfer surface 35b formed around the optical transfer surface 35a And are formed. Each optical transfer surface 35a is an aspheric surface obtained by inverting the optical surfaces of the component lenses constituting the lens array, and has an optical axis TX extending parallel to the Z axis. The support portion transfer surface 35b has two steps on the center side and the outer periphery side, but the surfaces 45d and 45e are flat and extend in parallel with the XY plane.
The core portion 32a is formed by using, for example, stainless steel, super steel, or another steel material as a base material, and the optical transfer surface 35a and the like are formed by finishing the surface of the NiP plated layer covering the base material. Furthermore, the entire surface of the core portion 32a can be coated with a release agent.
The end face of the peripheral portion 32 b is a parting surface PA 2 used when abutting the second mold 32 to the first mold 31.

  As shown in FIG. 2, the molding surface 31 t of the core portion 31 a constituting the first molding die 31 is formed by a cutting tool 80 provided in a processing device described in detail later. The cutting tool 80 can be rotated at a high speed around a rotation axis RX formed of, for example, an end mill or the like and set in principle parallel to the Z axis or the optical axis TX, and the attitude of the rotation axis RX is maintained. The core portion 31a can be moved at any timing and speed in the directions of the three XYZ axes with respect to the core portion 31a. The respective optical transfer surfaces 34a constituting the forming surface 31t are sequentially ground and individually finished by the cutting tool 80 one by one. Each of the optical transfer surfaces 34a basically has an axially symmetric or rotationally symmetric shape based on the optical axis TX, but may have a slightly modified shape. For example, by operating the tip portion 81a of the cutting tool 80 to turn around the optical axis TX while rotating it around the rotation axis RX, the obtained optical transfer surface 34a has high symmetry around the optical axis TX. It is possible to secure the state of having. The support portion transfer surface 34 b is formed after or before processing of the optical transfer surface 34 a by the cutting tool 80. At this time, for example, the cutting tool 80 is moved linearly along the XY plane while performing a scan gradually shifting in the vertical direction. Although the support portion transfer surface 34b is originally a flat surface parallel to the XY plane, shape correction is performed so as to offset the shape error of the finished product, and it is generally not as defined by a free-form surface equation. It has a regular wave shape.

  With reference to FIGS. 3A and 3B, the lens array 10 as a molded article produced by the molding apparatus 30 shown in FIG. 1 will be described. The lens array 10 is an integral body formed of a thermoplastic resin which is an optical material, and has a rectangular (including square) outline with an outer frame. The lens array 10 has a plurality of lens elements 10a, each of which is an optical element, and a flange portion 10f that supports the plurality of lens elements 10a from the periphery. The flange portion 10 f includes an inter-lens flange portion 10 c between the lens elements 10 a and an outer peripheral flange portion 10 d at the outer peripheral portion of the first lens array 10. The plurality of lens elements 10a constituting the first lens array 10 have optical axes OA parallel to each other on rectangular grid points (16 points of 4 × 4 in the illustrated example) arranged in parallel to the xy plane. Two-dimensionally arranged in the state. Each lens element 10a has a convex optical surface 11a on the first major surface 10p, and a convex optical surface 11b on the second major surface 10q, and the two optical surfaces 11a and 11b are axisymmetrical surfaces, Specifically, for example, it is an aspheric surface. The inter-lens flange portion 10c is a flat portion in the form of a flat plate, has a flange surface 11c on the object side, and has a flange surface 11d on the image side. The outer peripheral flange portion 10d is a thick portion in the shape of a rectangular frame, and functions as a spacer when fixing the lens array 10 to another lens array, a holder or the like.

  FIG. 4 is a block diagram schematically illustrating an example of the structure of a processing apparatus used to process the molding surfaces 31t and 32t of the first and second molds 31 and 32 shown in FIG. The processing apparatus 100 includes an NC drive mechanism 91 that enables cutting that relatively moves the cutting tool 80 while supporting the workpiece W, a drive control device 97 that controls the operation of the NC drive mechanism 91, and the entire apparatus. And a main controller 98 that controls the operation in an integrated manner. The NC drive mechanism 91 has a structure in which a first processing stage 94 b and a second processing stage 94 c are mounted on a pedestal 94 a. Here, the first processing stage 94b supports the first movable portion 95a, and the first movable portion 95a indirectly supports the workpiece W via the stage portion 95b. The first processing stage 94b can rotate the first movable portion 95a and the stage portion 95b around the rotation axis RA parallel to the γ axis, and the first movable portion 95a rotates the work W through the stage portion 95b. It can be placed at a desired position along, for example, the α and β axis directions while supporting. That is, the workpiece W can be rotated at a desired speed about a rotation axis RA extending in a direction substantially perpendicular to the entire surface Wa through any point on the surface Wa. On the other hand, the second processing stage 94c supports the second movable portion 95c, and the second movable portion 95c supports the cutting tool 80. The second processing stage 94c supports the second movable portion 95c and the cutting tool 80, and can move them to a desired position along, for example, the α and β axis directions at a desired speed. Further, the second movable portion 95c can support the cutting tool 80 and move it at a desired speed at a desired position, for example, in the γ-axis direction. Also, the second movable portion 95c can pivot the cutting tool 80, for example, through the tip end 81a about a rotation axis RX parallel to the γ axis, and if necessary, a vertical pivot axis passing through the tip end 81a. The cutting tool 80 can also be rotated or tilted about the desired angle to adjust the attitude of the cutting tool 80.

  The drive control device 97 enables high precision numerical control, and drives the motor and the position sensor, etc. built in the NC drive mechanism 91 under the control of the main control device 98. 2) The processing stages 94b and 94c and the first and second movable parts 95a and 95c are appropriately operated in a targeted state. For example, the work W is rotated at high speed around the rotation axis RA by the first processing stage 94 b. At this time, the turning center of the workpiece W can be made to coincide with any one of the positions that should be the multiple optical axes TX by the first movable portion 95a. On the other hand, the processing point of the tip portion 81a of the cutting tool 80 is first arranged on the rotation axis RA by the second processing stage 94c, and the tip portion 81a is moved at low speed in the α or β axis direction (feed operation). In parallel with this, the second movable portion 95c gradually moves the tip end portion 81a back and forth in the γ-axis direction while rotating the cutting tool 80 around the rotation axis RX. Thereby, the NC drive mechanism 91 can be operated as a lathe capable of changing the processing position, and a concave or convex axially symmetrical surface having a desired shape can be formed at an arbitrary position on the work W, for example A core portion 31a having a molding surface 31t as shown in 2 can be obtained.

  The main control device 98 has a storage unit (not shown) for storing information on the processing shape of the workpiece W. The information on the processing shape of the workpiece W includes the steps of operating the first and second processing stages 94b and 94c and the first and second movable parts 95a and 95c, and more specifically, the core portions 31a and 32a. It is possible to store the shape of the forming surfaces 31t and 32t and the locus of relative movement of the tip 81a of the cutting tool 80 with respect to the surface Wa of the workpiece W that can be derived from this shape. That is, the main controller 98 stores not only the shape of the designed molding surfaces 31t and 32t but also the shape of the molding surfaces 31t and 32t corrected or corrected to obtain the desired molded product shape. Of the molding surfaces 31t and 32t of the core portions 31a and 32a, the optical transfer surfaces 34a and 35a are disposed on lattice points as rotationally symmetrical axially symmetrical surfaces with respect to the optical axis TX in the original design, The transfer surfaces 34 b and 35 b are flat surfaces perpendicular to the optical axis TX. The data of such a shape and the corresponding trajectory of the cutting tool 80 correspond to an axially symmetric surface shape, and will be hereinafter referred to as axisymmetric machining data. The apexes of the plurality of optical transfer surfaces 34a and 35a are on the same plane in the original design, but when correction is performed in consideration of the shape after molding, the distance relatively changes by an increase and decrease by free curved surface expression It is placed on a non-axisymmetric surface (wave surface) as defined. Similarly, the support portion transfer surfaces 34b and 35b are also corrected to surfaces having such an undulation shape when correction is performed. The data of such a shape and the trajectory of the cutting tool 80 corresponding thereto are different from the axisymmetric machining data and correspond to a non-axisymmetric surface shape, and hereinafter also referred to as non-axisymmetric machining data.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ：曲率半径
Ｋ：円錐定数
なお、光学転写面３４ａの目標とする形状は、一般的には上記非球面式によって表現されるが、レンズアレイ１０の目的等に応じて好ましい特性が得られるように非球面式の係数Ａｉが調整される。Hereinafter, with reference to FIG. 5, the manufacturing method of the core part 31a of the shaping | molding die 31 shown to FIG. 1, 2 grade | etc., Is demonstrated. First, axially symmetric processing data for processing the target forming surface 31t is created (step S11). Here, the axisymmetric processing data for the forming surface 31t corresponds to the design value of the shape of the objective lens array 10, and is based on the expression of the axisymmetric surface. Specifically, the axisymmetric processing data is obtained by arranging aspheric surfaces corresponding to the optical transfer surface 34 a for transferring the lens element 10 a at 4 × 4 lattice points. Here, the shape of each aspheric surface can be expressed by a known aspheric equation. Specifically, with the apex of the optical transfer surface 34a as the origin, the Z axis is taken in the direction of the optical axis TX, the optical axis TX And the height in the vertical direction is represented by the following formula or expression.

However,
Ai: i-th order aspheric coefficient R: curvature radius K: conical constant The target shape of the optical transfer surface 34a is generally expressed by the above aspheric expression, but for the purpose of the lens array 10, etc. Accordingly, the coefficient Ai of the aspheric equation is adjusted to obtain desirable characteristics.

Next, based on the axisymmetric machining data determined in step S11, a simulation mold is preliminarily prepared (step S12). The processing apparatus 100 of FIG. 4 is used for trial manufacture of a simulation type. The simulated mold is a practical mold having substantially the same shape as the first mold 31 and capable of experimental molding, but no correction is made by feedback from shape measurement of the molded product. . That is, in actual molding, the molds 31 and 32 are placed in an environment affected by deformation and inclination, and the molded product is also deformed such as bending and contraction due to factors such as the influence of the heat process. Furthermore, due to the deviation of the errors caused by the operations of the processing apparatus 100 and the cutting tool 80, there is a possibility that the shape is not processed as designed but has a certain tendency. For this reason, even if the molds 31 and 32 have an ideal shape, the shape of the lens array 10 can not be made as designed, and in order to make the shape of the lens array 10 as designed, As a result, it is necessary to process the molding surfaces 31t and 32t of the molds 31 and 32 into a shape that is forcibly corrected. The shapes of the plurality of optical transfer surfaces 34a and 35a constituting the forming surfaces 31t and 32t may be the same, but may be slightly different from one another.
With reference to FIG. 4, the production of the simulated mold will be specifically described. First, the workpiece W which is the source of the simulation type is set on the stage unit 95 b. The work W has substantially the same shape as the first mold 31 shown in FIG. 1 and has a NiP plating layer formed on the surface, but the portion corresponding to the optical transfer surface 34a is shallow. Thereafter, processing is performed based on the axially symmetric processing data in optical design, and a molding surface similar to the molding surface 31 t provided on the core portion 31 a of the first molding die 31 shown in FIG. 1 is processed. At this time, the optical transfer surface 34 a arranged at 4 × 4 lattice points is sequentially processed. When processing the specific optical transfer surface 34a, the tip 81a of the cutting tool 80 is made to coincide with the optical axis TX which is the rotation center of the work W while rotating the cutting tool 80 supported by the second movable portion 95c. The distal end portion 81a is also displaced in the direction of the optical axis TX while being moved so as to gradually separate from the optical axis TX. Thereby, the tip end portion 81a of the cutting tool 80 cuts out the optical transfer surface 34a while drawing a spiral along the aspheric surface. Hereinafter, such movement of the tip portion 81a of the cutting tool 80 will be referred to as a helical scan. Thus, when the processing of the specific optical transfer surface 34a is finished, the next processing of the optical transfer surface 34a is similarly performed by spiral scanning. By repeating this, 16 optical transfer surfaces 34 a are obtained. The apexes of these optical transfer surfaces 34a are ideally on the same plane parallel to the XY plane or the αβ plane. With respect to the support portion transfer surface 34b, while rotating the tip portion 81a of the cutting tool 80, using the first movable portion 95a, for example, it is perpendicular to the main scan along a plurality of main scan lines extending in parallel. By performing the sub-scan to move gradually in the direction, it is possible to make the surface approximately smooth parallel to the XY plane or the αβ plane. Such movement of the tip portion 81a of the cutting tool 80 is referred to as raster type scanning. Thus, the first molding die 31 as a simulated die is obtained.
Although a detailed description is omitted, the second mold 32 as a simulation mold is also manufactured in the same manner as the first mold 31 as a simulation mold. As a result, it is possible to obtain the second mold 32 having a large number of optical transfer surfaces 35a processed based on the axisymmetric processing data and a support portion transfer surface 35b connecting the optical transfer surfaces 35a as a simulation mold. it can. In this embodiment, the simulation type and the production type to be described later are different. However, if the simulation type can be coped with by additional processing, it can be diverted as the production type.

Next, the lens array 10 is experimentally manufactured using the molds 31 and 32 obtained in step S12. The manufacturing process and molding conditions of the prototype lens array 10 are made to substantially coincide with the real manufacturing process and molding conditions (step S13).
The trial manufacture of the lens array 10 will be specifically described with reference to FIG. FIG. 6 is a view for explaining the molding apparatus 30 for molding the lens array 10 in relation to the mold space, and is provided with the first and second molds 31 and 32, which are also shown in FIG. The two molds 31, 32 are put together to form a cavity 30a. The runner RA is connected to the cavity 30a via the gate GA, and the runner RA is connected to the sprue SP on the resin supply side. As a result, the molten resin J from the sprue SP obtained by melting the thermoplastic resin fills the runner RA and fills the cavity 30a via the gate GA. By separating the first mold 31 and the second mold 32 after cooling the molten resin J, the sprue portion 71 corresponding to the sprue SP, the runner portion 72 corresponding to the runner RA, and the gate GA are supported. A molded article 70 is formed which includes the gate portion 73 and the lens array main body 74 corresponding to the cavity 30a. Here, gate cutting processing is performed on the gate section 73, and the lens array main body 74 at the tip of the gate section 73 provides a prototype lens array 10.

  Next, the prototype lens array 10 obtained in step S13 is measured (step S14). For measurement of the lens array 10, a three-dimensional measurement device that enables shape measurement of the optical surface is used. The three-dimensional measuring apparatus is one in which a known mechanism disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2007-147371 and 2013-210331 is incorporated. At the time of measurement, the shapes of the optical surfaces 11a and 11b of all the lens elements 10a constituting the lens array 10 are measured, and the extent to which these optical surfaces 11a and 11b deviate from the target aspheric shape Amount) and the extent (deviation amount) in which the optical axis OA corresponding to the vertex position of each of the optical surfaces 11a and 11b deviates from the target lattice point. Specifically, the stylus for measurement is moved along any optical surface 11a, for example, in the x direction, and then the stylus for measurement is moved, for example, in the y direction along the optical surface 11a, Basic information on the shape and arrangement of the optical surface 11a can be obtained. Further, by measuring the flange surfaces 11c and 11d, it is possible to obtain information on the surface shape of the flange portion 10f.

  Next, based on the measurement result obtained in step S14, an error component (that is, an amount of error) is extracted for each of the optical surfaces 11a and 11b provided in the lens array 10 (step S15). In this step, for each of the optical surfaces 11a and 11b, the amount of deviation from the target value of the vertex position through which the optical axis OA passes or the amount of deviation from the target aspheric surface shape may be evaluated as an error component (error amount). it can. The amount of deviation of the vertex position of each of the optical surfaces 11 a and 11 b from the target value is the undulation shape or distortion of the flange portion 10 f of the lens array 10. When the original shapes of the plurality of optical transfer surfaces 34a, 35a constituting the forming surfaces 31t, 32t are slightly different, that is, when the plurality of types of optical transfer surfaces 34a, 35a are premised, the optical surfaces 11a, 11b. Since the shapes of are slightly different from each other, the degree of deviation from the target aspheric shape also takes into consideration the difference in the inherent shape of the plurality of optical transfer surfaces 34a and 35a. As the plurality of types of optical transfer surfaces 34a and 35a, it is conceivable to use RGB colors, use according to the angle of view, and use according to the deflection surface.

Next, based on the error component (error amount) obtained in step S15, the main controller 98 sets the first of the optical transfer surfaces 34a and 35a as an amount to compensate for the deviation of the optical surfaces 11a and 11b by trial manufacture. A correction amount (hereinafter also referred to as a compensation amount) is determined (step S16). That is, the first correction amount (compensation for forming non-axisymmetric processed data) is the data (non-axisymmetric component) in which the measured vertex positions of the optical surfaces 11a and 11b are defined on an approximate non-axisymmetric surface. Amount) is stored in the main controller 98. Specifically, the deviation amount from the target value of the vertex position of each of the optical surfaces 11a and 11b is expressed by a non-axisymmetric surface (wave surface) as defined by a free curved surface equation, and each of the optical surfaces 11a and 11b The vertex position of is changed to the data defined on the non-axisymmetric surface, and the inverted one thereof becomes the non-axisymmetric processed data for compensation. At this time, fitting to a free-form surface using a method of least squares or the like is performed. In addition, the above-mentioned non-axisymmetric surface as defined by a free-form surface equation can be additionally obtained from the shapes of the flange surfaces 11c and 11d. The shape of the non-axisymmetric free-form surface can be, for example, the following equation or expression using a Zernike polynomial.
W (ρ, θ) = Σ {An · Zn (ρ, θ)}
W: non-axisymmetric surface (fitting with measured data)
Zn: Zernike term An: coefficient of each term :: (distance from center of measurement point) / (radius of data measurement range)
As
Z1 = 1
Z2 = ρ cos θ
Z3 = ρsinθ
Z4 = 2ρ ² -1
Z5 = ^{2 2} sin 2θ
...
The above first correction amount (compensation amount) should not exceed 10 μm at maximum. By providing such a limitation, the first correction amount related to the non-axisymmetric surface is set to a relatively small value, and deterioration in the shape accuracy of the mold due to excessive correction or compensation is suppressed. Conversely, when the first correction amount exceeds 10 μm, it may be considered to cope with the molding condition of the lens array 10, the shape change of the inter-lens flange portion 10c, or the like.

  7A and 7B are diagrams for explaining the first correction amount set on the molding surface 31t of the first molding die 31. FIG. When the measurement result of the optical surface 11a of the lens array 10 has an undulation as shown in FIG. 7A (curved surface visually displayed by the flange surface 11c), the optical surface 11a on the left side of the drawing is relatively low. The right optical surface 11a is relatively high. In this case, the first correction amount (compensation amount) to be set on the optical transfer surface 34a of the molding die 31 is reversed as shown in FIG. 7B (curved surface visually displayed by the support portion transfer surface 34b) The That is, the optical transfer surface 34a on the left side of the drawing is relatively deep, and the optical transfer surface 34a on the right side of the drawing is relatively shallow. By setting such a correction amount, all the optical surfaces 11a of the lens array 10 obtained by the first mold 31 after correction have the same height.

  Next, initial data corresponding to the design value of the surface shape of the lens element 10a constituting the lens array 10 is read out (step S21). The initial data is axisymmetric processed data that can be defined as an aspheric surface as described in step S11. When the shapes of the plurality of optical transfer surfaces 34a and 35a constituting the forming surfaces 31t and 32t are slightly different, that is, when the plurality of types of optical transfer surfaces 34a and 35a are premised, initial data is prepared for each surface read out.

Next, one type of axially symmetric surface corresponding to the initial data is subjected to test processing (step S22). The test processing is performed by cutting the dummy work W using the processing apparatus 100 of FIG. 4. As the dummy work W, an original work W in which NIP plating or the like is applied to a super steel can be used, but the work W is made of different materials, specifically, for example, formed of oxygen free copper in consideration of cost. Can be used.
As shown in FIG. 8, although only one optical transfer surface 134a corresponding to the optical transfer surface 34a of the first mold 31 is formed on the dummy work W, a plurality of optical transfer surfaces 134a are formed. It can also be done.

  Next, a test processed shape is measured for the dummy work W after test processing obtained in step S22 (step S23). For measurement of the dummy workpiece W, the three-dimensional measurement device used in step S14 is used. In the measurement, the shape of the optical transfer surface 134a formed on the dummy work W is measured, and the degree of deviation of the optical transfer surface 134a from the target aspheric shape is measured. Specifically, the stylus for measurement is moved two-dimensionally densely so as to perform main scanning and sub scanning along the optical transfer surface 134a, and relatively accurate information on the shape of the optical transfer surface 134a is obtained. When a plurality of optical transfer surfaces 134a are formed on the dummy work W, shape information is obtained for all the optical transfer surfaces 134a.

  Next, based on the measurement result obtained in step S23, an error component (that is, an amount of error) is extracted for the optical transfer surface 134a formed on the dummy workpiece W (step S24). In this step, the degree of deviation from the target aspheric shape is evaluated as an error component (error amount) for the optical transfer surface 134a. When a plurality of optical transfer surfaces 134a are formed on the dummy work W, statistical processing such as averaging of error components is performed.

  Next, based on the error component (error amount) obtained in step S24, the main controller 98 sets the second optical transfer surface 34a as the amount to be corrected to the original shape of the optical transfer surface 134a after test processing. A correction amount (hereinafter also referred to as a correction amount) is determined (step S25). That is, deviation data (axially symmetric component) from the design value of the measured optical transfer surface 134a is stored in the main control device 98 as a second correction amount (correction amount) which constitutes a part of the axisymmetric processed data. Specifically, deviation data from the design value is extracted as an axially symmetric component (for example, the shape of an aspheric surface). If the second correction amount is larger than expected, test processing can be performed by incorporating the already obtained second correction amount. That is, as for the second correction amount, by repeating steps S22 to S25 while feeding back the result of test processing, it is possible to set the second correction amount more precisely and appropriately as in the conventional method.

  After that, when there is another type of axial symmetry plane (optical transfer surface 34a) corresponding to the initial data (Y in step S26), the process returns to step S22 to test another type of axial symmetry plane among the initial data. . The subsequent processing is the same (steps S22 to S25), and by repeating this, the second correction amount is determined for all types of axially symmetric surfaces (optical transfer surface 34a) (step S25).

  When the second correction amount (correction amount) is determined for the axially symmetric surface (optical transfer surface 34a) corresponding to all types of design values (N in step S26), the axisymmetric machining data created in step S11 is corrected Non-axisymmetric machining data is obtained (step 1). Specifically, the first correction amount obtained in step S16 is added to the original axially symmetric processing data as a correction term for the whole, and the second correction amount obtained in step S25 corresponds to the corresponding optical transfer surface 34a. Is added as a correction term for

  In the above, the second correction amount and the like are obtained for the optical transfer surface 34a of the first molding die 31, but the second transfer amount is also obtained for the optical transfer surface 35a of the second molding die 32 by the same method as steps S22 to S27. A correction amount or the like is obtained (step S28).

  Finally, based on the non-axisymmetric machining data obtained in the steps S27 and S28, production first and second molds 31 and 32 are produced by the processing device 90 of FIG. The lens array 10 is manufactured using the above (step S29). The manufacturing process and molding conditions of the lens array 10 are made to coincide with those of the prototype lens array 10 in step S13.

  The lens array 10 obtained by the above method has a shape close to the shape as originally designed, and the lens array 10 having the target accuracy can be obtained by a quick and simple method. In addition, precise shape measurement is performed on the lens array 10 obtained by the above method using a three-dimensional measurement device, and the result is fitted by an aspheric surface equation, free curved surface equation, etc. By feeding back as the shape correction term of the molds 31 and 32, the shape of the lens array 10 can be brought closer to the design value more accurately. Even if such additional finishing correction is performed, the correction term can be made more accurate earlier than when performing accurate two-dimensional shape measurement from the beginning using the three-dimensional measuring device on the prototype lens array 10 Adoption becomes quick, and the time and effort from the design of the lens array 10 to the start of mass production can be greatly reduced.

  According to the method of manufacturing a mold according to the present embodiment, the non-axisymmetric surface is expressed based on the amount of error obtained by measurement of the lens array 10 molded by the molds 31 and 32 which are simulation molds. (1) The correction amount is calculated (step S16), and the plurality of optical transfer surfaces 34a and 35a of the molds 31 and 32 are processed based on the expression of the axisymmetric surface and the expression of the nonaxisymmetric surface (step The manufacturing of the lens array 10 having the plurality of optical surfaces 11a and 11b of the axisymmetric type can be simplified. That is, since trial manufacture and measurement are performed from the viewpoint of dividing the surface shape of the lens array 10 into the component of the axisymmetric surface and the component of the non-axisymmetric surface, the period from trial manufacture of the lens array 10 to obtaining a finished product is shortened. , That effort can be reduced.

  As mentioned above, although the manufacturing method etc. of the molding die concerning this embodiment were explained, the manufacturing method of the molding die concerning the present invention is not restricted to the above-mentioned thing. For example, the lens array 10 manufactured by the method of the said embodiment is not limited to what is used independently, and may be a lens array as an element at the time of laminating | stacking several lens arrays.

  In the step of performing test processing on the dummy work W, when the optical surface 11a of the lens array 10 is formed of a plurality of types, a plurality of optical transfer surfaces 134a corresponding to the plurality of types are collectively provided on the dummy work W It can also be formed.

  The shape measurement performed in steps S14 and S23 is not limited to the illustrated device and method, and various devices and methods can be used.

  In the above, although molding is performed by supplying a thermoplastic resin as a molding material between molding dies 31 and 32, a photocurable resin, a thermosetting resin, or the like can be used instead of the thermoplastic resin.

  Although the 4 × 4 lens array 10 has been described above, the same mold as that described in the above embodiment may be used to mold the 3 × 3 lens array and the 5 × 5 or more lens array. it can.

Claims (10)

A method of manufacturing a mold having a plurality of optical transfer surfaces for molding a lens array, comprising:
A simulated mold is produced by processing the plurality of optical transfer surfaces based on the expression of the axisymmetric surface,
An expression of a non-axisymmetric surface of each optical transfer surface unit is calculated based on an amount of error obtained by measurement of the lens array molded by the simulation mold;
A manufacturing method of a forming die for processing the plurality of optical transfer surfaces of the forming die based on the expression of the axisymmetric surface and the expression of the non-axisymmetric surface.   The expression of the non-axisymmetric surface is an expression expressed using at least one of an amount of deviation from a target value of a vertex position through which the optical axis passes and an amount of deviation from a target aspheric shape. A method of manufacturing a mold according to claim 1.   The molding according to any one of claims 1 and 2, wherein the expression of the non-axisymmetric surface is an expression in which the deviation amount from the target value of the vertex position of the optical transfer surface is defined by a free curved surface expression. Mold manufacturing method.   The method for manufacturing a mold according to any one of claims 1 to 3, wherein the maximum compensation amount according to the expression of the non-axisymmetric surface is 10 μm. A method of manufacturing a mold having a plurality of optical transfer surfaces for molding a lens array, comprising:
A simulated mold is manufactured by processing the plurality of optical transfer surfaces based on axisymmetric processing data which is a design value,
An expression of a non-axisymmetric surface of each optical transfer surface unit is calculated based on an amount of error obtained by measurement of the lens array molded by the simulation mold;
An expression of an axially symmetric surface is calculated by adding a correction amount obtained by test processing to the design value,
A manufacturing method of a forming die for processing the plurality of optical transfer surfaces of the forming die based on the expression of the axisymmetric surface and the expression of the non-axisymmetric surface.   The method for manufacturing a mold according to claim 5, wherein the test process is performed on a material different from the material of the mold. The mold includes, as the plurality of optical transfer surfaces, a plurality of types of optical transfer surfaces having different design values of the expression of the axisymmetric surface,
The expression of the axisymmetric surface is obtained by adding a plurality of correction amounts obtained by the test processing to a plurality of types of design values corresponding to the plurality of types of optical transfer surfaces, respectively. The manufacturing method of the shaping | molding die as described in any one of these.   The plurality of optical transfer surfaces have an optical axis parallel to each other, and the plurality of optical transfer surfaces are processed by a tool having a rotational axis parallel to the optical axis. The manufacturing method of the shaping | molding die as described in.   The method of manufacturing a mold according to any one of claims 1 to 8, wherein the expression of the non-axisymmetric surface is a free-form surface equation, and the axisymmetric surface is an aspheric surface.   The manufacturing method of a lens array which has the process of shape | molding using the shaping | molding die obtained by the manufacturing method of the shaping | molding die as described in any one of Claims 1-9.

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