WO2015194624A1

WO2015194624A1 - Method for producing mold and method for producing lens array

Info

Publication number: WO2015194624A1
Application number: PCT/JP2015/067574
Authority: WO
Inventors: 高木信; 本田貞春; 瀧谷俊哉
Original assignee: コニカミノルタ株式会社
Priority date: 2014-06-19
Filing date: 2015-06-18
Publication date: 2015-12-23
Also published as: JP6515927B2; JPWO2015194624A1

Abstract

Provided is a method for producing a mold for a lens array with which production is possible in a relatively short time with a simple technique. A first correction amount, which is an expression of a non-axisymmetric surface, is calculated on the basis of an amount of error obtained by measuring a lens array (10) molded with a mold (31, 32) which is a model mold (step S16), and a plurality of optical transfer surfaces (34a, 35a) on the mold (31, 32) are processed on the basis of an expression of an axisymmetric surface and the expression of the non-axisymmetric surface (steps S27 and S28). Thus, it is possible to easily produce a lens array (10) having a plurality of axisymmetric optical surfaces (11a, 11b).

Description

Mold manufacturing method and lens array manufacturing method

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

As a processing method of the lens array, a work to be a mold is prepared, a part corresponding to one array element in the center is first processed, and an eccentric error and a shape error with respect to the entire mold are measured. There is a technique in which machining data is corrected so that an error and a shape error are equal to or less than allowable values, and parts corresponding to all other array elements are processed using the corrected machining data (see Patent Document 1). Regarding this processing method, it is also described that warpage and shrinkage are corrected by measuring the deformation due to warpage and shrinkage of the actually shaped array-shaped element as a shape error and changing the cutting depth of the machining tool. .

However, in the method described in Patent Document 1, since the deviation from the ideal value is measured by measuring the shape of the array-shaped element including the individual array elements, the measurement takes a long time, and from the beginning of the measurement. It is not easy to maintain measurement accuracy until the end. Moreover, the operation | work which converts the deviation | shift from an ideal value into the locus | trajectory of a tool about each array element is not necessarily easy, and time and labor from a prototype to obtaining a completed product may become enormous.

JP 2007-276049 A

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

A first mold manufacturing method according to the present invention is a mold manufacturing method having a plurality of optical transfer surfaces for molding a lens array, and a plurality of optical transfer surfaces based on an expression of an axially symmetric surface. A non-axisymmetric plane expression is calculated based on the amount of error obtained by measuring the lens array molded by the mock mold. A plurality of optical transfer surfaces of the mold are processed based on the surface expression. Here, the expression is not limited to a general mathematical expression including variables, arithmetic expressions, and the like, but also 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 error amount obtained by the measurement of the lens array formed by the simulated mold, and the expression of the axially symmetric surface and the expression of the non-axisymmetric surface are calculated. Since the processing of the plurality of optical transfer surfaces of the mold is performed based on this, it is possible to easily manufacture the mold of the lens array including the plurality of axially symmetric optical surfaces. In other words, since the prototype and measurement are performed from the viewpoint of dividing the surface shape of the lens array into the components of the axisymmetric surface and the components of the non-axisymmetric surface, the period from the prototype of the lens array to the completion of the finished product is shortened. Labor can be reduced.

According to a specific aspect of the present invention, in the above manufacturing method, the expression of the non-axisymmetric surface includes the deviation amount from the target value of the vertex position through which the optical axis passes and the deviation amount from the target aspherical shape. An expression expressed using at least one of the following.

According to another aspect of the present invention, 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-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 related to the non-axisymmetric surface is relatively small, and the shape accuracy of the mold is relatively easy to increase.

A second mold manufacturing method according to the present invention is a mold manufacturing method having a plurality of optical transfer surfaces for molding a lens array, and a plurality of optical molds based on axisymmetric processing data as design values. A simulated mold is produced by processing the transfer surface, and the expression of the non-axisymmetric surface is calculated based on the error amount obtained by measuring the lens array molded by the simulated mold. The expression of the axially symmetric surface to which the correction amount is added is calculated, and a plurality of optical transfer surfaces of the mold are processed based on the expression of the axially symmetric surface and the expression of the non-axisymmetric surface.

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 molded by the simulated mold, and the design value is added to the correction amount obtained by the test processing. Since the surface expression is calculated and the plurality of optical transfer surfaces of the molding die are processed based on the expression of the axially symmetric surface and the expression of the non-axisymmetric surface, a plurality of axially symmetric optical surfaces are provided. The manufacturing of the lens array mold can be simplified. In particular, when the expression of the axially symmetric surface is obtained by adding the correction amount obtained by the test processing to the design value, the shape accuracy of the element lenses constituting the lens array can be increased.

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

According to another aspect of the present invention, the mold has, as a plurality of optical transfer surfaces, a plurality of types of optical transfer surfaces having different design values for the expression of the axially symmetric surface, and the expression of the axially symmetric surface is: A plurality of correction values obtained by test processing are 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 a case where the lens array includes a plurality of types of element lenses. Note that the plural types of element lenses may have different corresponding wavelengths, different fields of view, and 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 rotation axis parallel to the optical axis. In this case, it is easy to align the shapes of the plurality of optical transfer surfaces processed on the mold by the tool, and it is easy to improve the processing accuracy.

According to another aspect of the present 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 according to the present invention includes a step of performing molding using the molding die obtained by the above manufacturing method.

In the manufacturing method, since the molding is performed using the molding die obtained by the manufacturing method of the molding die, it is possible to easily manufacture a lens array having a plurality of axially symmetric optical surfaces. The time required to obtain a finished product can be shortened, and the labor can be reduced.

It is a figure which illustrates notionally the shaping | molding die apparatus provided with the shaping | molding die concerning 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 sectional view for explaining a molded product manufactured by the molding die apparatus of FIG. It is a block diagram explaining the processing apparatus of a shaping | molding die. It is a flowchart explaining the manufacturing method of a shaping | molding die. It is sectional drawing explaining the shaping | molding process of a lens array. 7A and 7B are diagrams illustrating the first correction amount set on the molding surface of the mold. It is a perspective view explaining the test process by a dummy workpiece | work.

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

A molding apparatus 30 shown in FIG. 1 includes a pair of molding dies 31 and 32, and both molding dies 31 and 32 are relatively displaced in the AB direction parallel to the Z axis by a driving device 40, whereby both molding dies 31 are provided. , 32 can be opened and closed. A mold space surrounded by

molding surfaces

31t and 32t provided on both mold dies 31 and 32 is formed by closing the

molds

31 and 32. By injecting molten resin into the mold spaces, the

molding surfaces

31t and 32t are formed. It is possible to obtain a molded article, that is, a lens array, having an outer shape corresponding to.

The 1st shaping | molding die 31 is provided with the core part 31a which forms the molding surface 31t, and the surrounding part 31b which supports the core part 31a. The end surface of the core portion 31a on the first mold 31 side has a large number of optical transfer surfaces 34a arranged in a matrix parallel to the XY plane, and a support transfer surface 34b formed around the optical transfer surface 34a. 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 in parallel with the Z axis. That is, a large number of optical transfer surfaces 34a arranged on the lattice points are the same or similar aspheric surfaces having optical axes TX parallel to each other. The support 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 other steel as a base material, and the optical transfer surface 34a or the like is formed by finishing the surface of the NiP plating layer that covers the base material. Furthermore, the entire surface of the core portion 31a can be covered with a release agent.
The end surface of the peripheral portion 31b is a parting surface PA1 used when the first molding die 31 is abutted against the second molding die 32.

The 2nd shaping | molding die 32 is provided with the core part 32a which forms the molding surface 32t, and the surrounding part 32b which supports the core part 32a. The end surface of the core portion 32a on the second mold 32 side has a large number of optical transfer surfaces 35a arranged in a matrix parallel to the XY plane, and a support 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 element lenses constituting the lens array, and has an optical axis TX extending in parallel with the Z axis. The support portion transfer surface 35b has two steps on the center side and the outer peripheral side, but the

surfaces

45d and 45e are flat and extend in parallel to the XY plane.
The core portion 32a is formed by using, for example, stainless steel, super steel, or other steel as a base material, and the optical transfer surface 35a and the like are formed by finishing the surface of the NiP plating layer that covers the base material. Furthermore, the entire surface of the core portion 32a can be covered with a release agent.
The end surface of the peripheral portion 32 b is a parting surface PA <b> 2 that is used when the second mold 32 is brought into contact with the first mold 31.

As shown in FIG. 2, the molding surface 31t of the core portion 31a constituting the first molding die 31 is formed by a cutting tool 80 provided in a machining apparatus described in detail later. The cutting tool 80 is formed by an end mill, for example, and can be rotated at high speed around a rotation axis RX set in parallel with the Z axis or the optical axis TX in principle, and the posture of the rotation axis RX is maintained. The core portion 31a can be moved at arbitrary timing and speed in the directions of the three axes XYZ. Each optical transfer surface 34a constituting the molding surface 31t is individually ground and sequentially finished by the cutting tool 80. Each optical transfer surface 34a basically has an axially symmetric or rotationally symmetric shape with respect to the optical axis TX, but may have a slightly modified shape. For example, the optical transfer surface 34a obtained has high symmetry around the optical axis TX by causing the tip 81a of the cutting tool 80 to rotate around the optical axis TX while rotating around the rotation axis RX. It is possible to ensure the state of having. The support portion transfer surface 34b is formed by the cutting tool 80 after or before the processing of the optical transfer surface 34a. At this time, for example, scanning is performed in which the cutting tool 80 is linearly moved along the XY plane and gradually shifted in the vertical direction. The support portion transfer surface 34b is originally a flat surface parallel to the XY plane, but is subjected to shape correction so as to cancel out the shape error of the finished product, and is generally not defined as a free-form surface equation. It has a regular waviness shape.

3A and 3B, the lens array 10 as a molded product 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 includes 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 lattice points (16 × 4 × 4 in the illustrated example) arranged in parallel to the xy plane. It is arranged in a two-dimensional state. Each lens element 10a has a convex optical surface 11a on the first main surface 10p, a convex optical surface 11b on the second main surface 10q, and both

optical surfaces

11a and 11b are axisymmetric surfaces, Specifically, it is an aspherical surface, for example. The inter-lens flange portion 10c is a flat plate-like flat portion having a flange surface 11c on the object side and a flange surface 11d on the image side. The outer peripheral flange portion 10d is a rectangular frame-shaped thick portion, and functions as a spacer when the lens array 10 is fixed 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 for processing the molding surfaces 31t and 32t of the first and second molding dies 31 and 32 shown in FIG. The machining 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 apparatus 97 that controls the operation of the NC drive mechanism 91, and an overall 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 94b and a second processing stage 94c are placed on a pedestal 94a. Here, the first processing stage 94b supports the first movable part 95a, and the first movable part 95a indirectly supports the workpiece W via the stage part 95b. The first processing stage 94b can rotate the first movable portion 95a and the stage portion 95b around a rotation axis RA parallel to the γ axis, and the first movable portion 95a moves the workpiece W via the stage portion 95b. For example, it can be arranged at a desired position along the α and β axis directions while being supported. That is, the workpiece W can be rotated at a desired speed around the rotation axis RA extending in a direction substantially perpendicular to the entire surface Wa through an arbitrary point on the surface Wa. On the other hand, the second machining stage 94c supports the second movable portion 95c, and the second movable portion 95c supports the cutting tool 80. The second processing stage 94c can support the second movable portion 95c and the cutting tool 80, and move them to desired positions 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 to a desired position along the γ-axis direction at a desired speed, for example. Further, the second movable portion 95c can turn the cutting tool 80, for example, around the rotation axis RX parallel to the γ axis through the tip portion 81a, and if necessary, a vertical turning axis passing through the tip portion 81a. It is also possible to adjust the posture of the cutting tool 80 by rotating or tilting the cutting tool 80 about a desired angle.

The drive control device 97 enables high-precision numerical control, and drives the motor and the position sensor built in the NC drive mechanism 91 under the control of the main control device 98, so that the first and the first The two

processing stages

94b and 94c and the first and second

movable parts

95a and 95c are appropriately operated to a target state. For example, the workpiece W is rotated around the rotation axis RA at a high speed by the first processing stage 94b. At this time, the turning center of the workpiece W can be made to coincide with any one of the positions to be the many optical axes TX by the first movable portion 95a. On the other hand, the machining point of the tip 81a of the cutting tool 80 is first placed on the rotation axis RA by the second machining stage 94c, and the tip 81a is moved (feeded) at a low speed in the α or β axis direction. In parallel with this, the second movable portion 95c gradually moves the tip portion 81a forward and backward in the γ-axis direction while rotating the cutting tool 80 around the rotation axis RX. Accordingly, the NC drive mechanism 91 can be operated as a lathe capable of changing the machining position, and a concave or convex axisymmetric surface having a desired shape can be formed at an arbitrary position on the workpiece W. A core portion 31a having a molding surface 31t as shown in FIG.

The main controller 98 has a storage unit (not shown) that stores information related to the machining shape of the workpiece W. The information regarding the machining shape of the workpiece W includes a step of operating the first and second machining stages 94b and 94c and the first and second

movable parts

95a and 95c, and more specifically, the

core portions

31a and 32a. The shape of the molding 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 in order to obtain this shape can be stored. 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 that have been 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 arranged on lattice points as axially symmetric surfaces that are rotationally symmetric with respect to the optical axis TX in the original design. The transfer surfaces 34b and 35b are flat surfaces perpendicular to the optical axis TX. Data of such a shape and the trajectory of the cutting tool 80 corresponding to this shape corresponds to an axially symmetric surface shape, and is hereinafter also referred to as axially symmetric processing data. The vertices of the plurality of optical transfer surfaces 34a and 35a are on the same plane in the original design. However, when correction is made in consideration of after molding, the interval is relatively increased or decreased, and is expressed by a free-form surface formula. It is arranged on a non-axisymmetric surface (swell surface) as defined. Similarly, the support portion transfer surfaces 34b and 35b are also corrected to surfaces having such a wavy shape when correction is performed. Unlike the above-described axially symmetric processing data, such a shape and the corresponding locus data of the cutting tool 80 correspond to a non-axisymmetric surface shape and are also referred to as non-axisymmetric processing data below.

Hereinafter, with reference to FIG. 5, the manufacturing method of the core part 31a of the shaping | molding die 31 shown in FIG. First, axisymmetric processing data for processing the target molding surface 31t is created (step S11). Here, the axially symmetric processing data for the molding surface 31t corresponds to the design value of the shape of the target lens array 10, and is based on the expression of the axially symmetric surface. Specifically, the axially symmetric processing data is obtained by arranging aspheric surfaces corresponding to the optical transfer surface 34a for transferring the lens element 10a at 4 × 4 lattice points. Here, the shape of each aspheric surface can be expressed by a known aspherical expression. Specifically, the vertex of the optical transfer surface 34a is the origin, the Z axis is taken in the direction of the optical axis TX, and the optical axis TX And the height in the vertical direction is represented by the following formula or expression.

However,
Ai: i-order aspherical coefficient R: radius of curvature K: conical constant The target shape of the optical transfer surface 34a is generally expressed by the above-mentioned aspherical expression, but for purposes of the lens array 10, etc. Accordingly, the aspherical coefficient Ai is adjusted so as to obtain preferable characteristics.

Next, a simulated mold is preliminarily produced based on the axisymmetric machining data determined in step S11 (step S12). For the simulation prototype, the processing apparatus 100 shown in FIG. 4 is used. The simulated mold is a practical mold that has substantially the same shape as the first mold 31 and can be experimentally molded, but is not corrected by feedback from the shape measurement of the molded product. . That is, in actual molding, the

molds

31 and 32 are placed in an environment that is affected by deformation and inclination, and the molded product is also subjected to deformation actions such as bending and shrinkage due to factors such as the influence of the thermal process. Furthermore, there is a possibility that a shape having a certain tendency is not processed as designed due to a deviation in error caused by the operation of the processing apparatus 100 or the cutting tool 80. For this reason, even if the

molds

31 and 32 have an ideal shape, the shape of the lens array 10 cannot be made as designed, and in order to make the shape of the lens array 10 as designed, it will be described later. Thus, it is necessary to process the molding surfaces 31t and 32t of the molding dies 31 and 32 into a shape forcibly corrected. The shapes of the plurality of optical transfer surfaces 34a and 35a constituting the molding surfaces 31t and 32t may be the same, but may be slightly different and may be a plurality of types.
With reference to FIG. 4, the fabrication of the simulated mold will be specifically described. First, the workpiece W that is the basis of the simulation type is set on the stage unit 95b. The workpiece 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 the optical design, and a molding surface similar to the molding surface 31t provided on the core portion 31a of the first molding die 31 shown in FIG. 1 is processed. At this time, the optical transfer surfaces 34a arranged at 4 × 4 lattice points are 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 workpiece W, while rotating the cutting tool 80 supported by the second movable portion 95c. The tip portion 81a is also displaced in the direction of the optical axis TX while being moved away from the optical axis TX. Thereby, the front-end | tip part 81a of the cutting tool 80 cuts out the optical transfer surface 34a, drawing a spiral along an aspherical type. Hereinafter, such movement of the tip 81a of the cutting tool 80 is referred to as spiral scanning. When the processing of the specific optical transfer surface 34a is finished in this way, the processing of the next optical transfer surface 34a is similarly performed by spiral scanning. By repeating this, 16 optical transfer surfaces 34a 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. For the support portion transfer surface 34b, the first movable portion 95a is used to rotate the tip portion 81a of the cutting tool 80, for example, while performing main scanning along a plurality of main scanning lines extending in parallel, and is perpendicular thereto. By performing sub-scanning that gradually moves in the direction, a smooth surface that is substantially parallel to the XY plane or the αβ plane can be obtained. Such movement of the tip 81a of the cutting tool 80 is referred to as raster scanning. Thus, the first mold 31 as a simulation mold is obtained.
Although a detailed description is omitted, the second mold 32 as a simulated mold is also produced in the same manner as the first mold 31 as a simulated mold. As a result, the second molding die 32 having a large number of optical transfer surfaces 35a processed based on the axially symmetric processing data and the support portion transfer surface 35b connecting the optical transfer surfaces 35a can be obtained as a simulation die. it can. In the present embodiment, the simulation type and the production type described later are different, but if the simulation type can be dealt with by additional machining, it can be used as the production type.

Next, the lens array 10 is produced on a trial basis using the

molds

31 and 32 obtained in step S12. The manufacturing process and molding conditions of the prototype lens array 10 are substantially matched with the actual manufacturing process and molding conditions (step S13).
The lens array 10 will be specifically described with reference to FIG. FIG. 6 is a diagram for explaining the molding apparatus 30 for molding the lens array 10 with respect to the mold space, and includes first and second molding dies 31 and 32 shown in FIG. Both

molds

31, 32 are mold matched to form a cavity 30a. A runner RA is connected to the cavity 30a via a gate GA, and the runner RA is connected to a 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 through 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 product 70 is formed that includes a gate portion 73 to be processed and a lens array body 74 corresponding to the cavity 30a. Here, the gate section 73 is subjected to a gate cut process, and the prototype lens array 10 is obtained by the lens array body 74 at the tip of the gate section 73.

Next, the prototype lens array 10 obtained in step S13 is measured (step S14). For the measurement of the lens array 10, a three-dimensional measurement device that enables measurement of the shape of the optical surface is used. The three-dimensional measuring apparatus incorporates a known mechanism disclosed in, for example, Japanese Unexamined Patent Application Publication Nos. 2007-147371 and 2013-210331. At the time of measurement, the shape of the

optical surfaces

11a and 11b of all the lens elements 10a constituting the lens array 10 is measured, and the extent to which these

optical surfaces

11a and 11b deviate from the target aspherical shape (deviation). Amount) and the extent to which the optical axis OA corresponding to the apex position of each

optical surface

11a, 11b is displaced from the target lattice point (deviation amount) is measured. Specifically, by moving the measurement stylus along one of the optical surfaces 11a, for example, in the x direction, and then moving the measurement stylus along the optical surface 11a, for example, in the y direction, Basic information about the shape and arrangement of the optical surface 11a can be obtained. Moreover, the information regarding the surface shape of the flange part 10f can be obtained by measuring the flange surfaces 11c and 11d.

Next, based on the measurement result obtained in step S14, an error component (that is, an error amount) 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 deviation amount from the target value of the vertex position through which the optical axis OA passes or the deviation amount from the target aspherical shape can be evaluated as an error component (error amount). it can. The amount of deviation from the target value of the vertex position of each

optical surface

11a, 11b is the undulation shape or distortion of the flange portion 10f of the lens array 10. When the original shapes of the plurality of optical transfer surfaces 34a and 35a constituting the molding surfaces 31t and 32t are slightly different, that is, when a plurality of types of optical transfer surfaces 34a and 35a are assumed, the

optical surfaces

11a and 11b are used. Since the shapes of these are slightly different from each other, the degree of deviation from the target aspherical shape is considered in consideration of the difference in the original shapes of the plurality of optical transfer surfaces 34a and 35a. As the plurality of types of optical transfer surfaces 34a and 35a, there can be considered those for the purpose of RGB color classification, field angle use, and deflection surface use.

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 be compensated for the deviation of the

optical surfaces

11a and 11b due to trial manufacture. A correction amount (hereinafter also referred to as compensation amount) is determined (step S16). That is, the data (non-axisymmetric component) defined on the non-axisymmetric surface in which the measured vertex positions of the

optical surfaces

11a and 11b are approximated are used as the first correction amount (compensation). The amount is stored in the main controller 98. Specifically, the amount of deviation from the target value of the vertex position of each

optical surface

11a, 11b is expressed by a non-axisymmetric surface (swell surface) as defined by a free-form surface equation, and each

optical surface

11a, 11b. Is changed to data defined on the non-axisymmetric plane, and the inverted data becomes non-axisymmetric machining data for compensation. At this time, fitting to a free-form surface using a least square method or the like is performed. In addition, the non-axisymmetric surface as defined by a free-form surface equation can be supplementarily 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 mathematical expression or expression using a Zernike polynomial.
W (ρ, θ) = Σ {An · Zn (ρ, θ)}
W: Non-axisymmetric plane (fitting with measurement data)
Zn: Zernike term An: coefficient of each term ρ: (distance from center of measurement point) / (radius of data measurement range)
As
Z1 = 1
Z2 = ρcosθ
Z3 = ρsinθ
Z4 = 2ρ ² -1
Z5 = ρ ² sin2θ
...
The above first correction amount (compensation amount) does not exceed 10 μm at the maximum. By providing such a restriction, the first correction amount related to the non-axisymmetric surface is set to a relatively small value, and deterioration of the shape accuracy of the mold due to excessive correction or compensation is suppressed. Conversely, when the first correction amount exceeds 10 μm, it is conceivable to cope with the molding conditions of the lens array 10, the shape change of the inter-lens flange portion 10c, and 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 waviness (curved surface visually displayed by the flange surface 11c) as shown in FIG. 7A, 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 mold 31 is reversed as shown in FIG. 7B (curved surface visually displayed by the support portion transfer surface 34b). It will have. 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 corrected first molding die 31 have the same protrusion height.

Next, initial data corresponding to the design value of the surface shape of the lens elements 10a constituting the lens array 10 is read (step S21). This initial data is axisymmetric processing data that can be defined as an aspherical surface as described in step S11. When the shapes of the plurality of optical transfer surfaces 34a and 35a constituting the molding surfaces 31t and 32t are slightly different, that is, when a plurality of types of optical transfer surfaces 34a and 35a are assumed, initial data is obtained for each surface. read out.

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

Next, the test machining shape is measured for the dummy workpiece W after the test machining obtained in step S22 (step S23). For the measurement of the dummy workpiece W, the three-dimensional measuring device used in step S14 is used. In the measurement, the shape of the optical transfer surface 134a formed on the dummy workpiece W is measured, and the degree of deviation from the target aspherical shape of the optical transfer surface 134a is measured. Specifically, the measurement stylus is two-dimensionally densely moved so as to perform main scanning and sub-scanning along the optical transfer surface 134a, and relatively precise information regarding the shape of the optical transfer surface 134a is obtained. In addition, when the some optical transfer surface 134a is formed on the dummy workpiece | work W, shape information is acquired about all the optical transfer surfaces 134a.

Next, based on the measurement result obtained in step S23, an error component (that is, an error amount) is extracted from the optical transfer surface 134a formed on the dummy workpiece W (step S24). In this step, the degree of deviation of the optical transfer surface 134a from the target aspherical shape is evaluated as an error component (error amount). When a plurality of optical transfer surfaces 134a are formed on the dummy workpiece 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 of each optical transfer surface 34a as an amount to be corrected to the original shape of the optical transfer surface 134a after the test processing. A correction amount (hereinafter also referred to as a correction amount) is determined (step S25). That is, the measured deviation data (axisymmetric component) from the design value of the optical transfer surface 134a is stored in the main controller 98 as the second correction amount (correction amount) constituting a part of the axially symmetric processing data. Specifically, deviation data from the design value is extracted as an axially symmetric component (for example, an aspheric shape). When the second correction amount is larger than expected, the test process can be performed by incorporating the already obtained second correction amount. That is, for the second correction amount, by repeating steps S22 to S25 while feeding back the result of the test process, a more accurate and appropriate second correction amount can be set as in the conventional method.

Thereafter, if there is another type of axially symmetric surface (optical transfer surface 34a) corresponding to the initial data (Y in step S26), the process returns to step S22 to test-process another type of axially symmetric surface in the initial data. . The subsequent processing is the same (steps S22 to S25). 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 axially symmetric processing 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 axisymmetric machining data as a correction term relating to the whole, and the second correction amount obtained in step S25 is further added to the corresponding optical transfer surface 34a. Is added as a correction term for.

In the above, the second correction amount and the like have been obtained for the optical transfer surface 34a of the first mold 31. However, the second transfer amount 35a of the second mold 32 is also determined by the same method as in steps S22 to S27. A correction amount or the like is obtained (step S28).

Finally, based on the non-axisymmetric machining data obtained in steps S27 and S28, the first and second molding dies 31, 32 are produced by the machining apparatus 90 of FIG. The lens array 10 is manufactured using (Step S29). The manufacturing process and molding conditions of the lens array 10 are matched 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. The lens array 10 obtained by the above method is subjected to precise shape measurement using a three-dimensional measuring device, and the result is fitted with an aspherical expression, a free-form expression, etc., and the reciprocals of these fitting expressions are obtained. By feeding back as the shape correction terms 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 is made highly accurate at an earlier stage than when precise two-dimensional shape measurement is performed from the beginning on the prototype lens array 10 using a three-dimensional measuring device. The drive-in is quick, and the time and labor from the design of the lens array 10 to the start of mass production can be greatly reduced.

According to the manufacturing method of the mold according to the present embodiment, the expression for the non-axisymmetric surface is based on the error amount obtained by the measurement of the lens array 10 molded by the

molds

31 and 32 which are simulated molds. Since one correction amount is calculated (step S16), the plurality of optical transfer surfaces 34a and 35a of the

molds

31 and 32 are processed based on the expression of the axially symmetric surface and the expression of the non-axisymmetric surface (step S16). S27, S28), the lens array 10 including a plurality of axially symmetric

optical surfaces

11a, 11b can be easily manufactured. In other words, since the prototype and measurement are performed from the viewpoint of dividing the surface shape of the lens array 10 into the components of the axially symmetric surface and the components of the non-axisymmetric surface, the period from the prototype of the lens array 10 to the completion of the finished product is shortened. , That effort can be reduced.

As mentioned above, although the manufacturing method of the shaping | molding die concerning this embodiment, etc. were demonstrated, the manufacturing method of the shaping | molding die concerning this invention is not restricted to said thing. For example, the lens array 10 manufactured by the method of the above embodiment is not limited to one used alone, but may be a lens array as an element when a plurality of lens arrays are stacked.

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

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

In the above, a thermoplastic resin is supplied as a molding material between the

molds

31 and 32 to perform molding. However, 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 molding die as that described in the above embodiment can be used to mold a 3 × 3 lens array and a 5 × 5 or more lens array. it can.

Claims

A method for producing a mold having a plurality of optical transfer surfaces for molding a lens array,
A simulated mold is produced by processing the plurality of optical transfer surfaces based on the expression of the axially symmetric surface,
Calculate the expression of the non-axisymmetric surface based on the amount of error obtained by measurement of the lens array molded by the simulated mold,
A manufacturing method of a molding die for processing the plurality of optical transfer surfaces of the molding die based on an expression of the axially symmetric surface and an expression of the non-axisymmetric surface.
The expression of the non-axisymmetric surface is an expression expressed using at least one of the deviation from the target value of the vertex position through which the optical axis passes and the deviation from the target aspheric shape. The manufacturing method of the shaping | molding die of Claim 1.
3. The molding according to claim 1, wherein the expression of the non-axisymmetric surface is an expression in which a deviation amount from a target value of the vertex position of the optical transfer surface is defined by a free-form surface equation. Mold manufacturing method.
The method for producing a mold according to any one of claims 1 to 3, wherein a maximum compensation amount according to the expression of the non-axisymmetric surface is 10 μm.
A method for producing a mold having a plurality of optical transfer surfaces for molding a lens array,
A simulated mold is produced by machining the plurality of optical transfer surfaces based on axisymmetric machining data that is a design value,
Calculate the expression of the non-axisymmetric surface based on the amount of error obtained by measurement of the lens array molded by the simulated mold,
Calculate the expression of the axisymmetric surface by adding the correction amount obtained by test machining to the design value,
A manufacturing method of a molding die for processing the plurality of optical transfer surfaces of the molding die based on an expression of the axially symmetric surface and an expression of the non-axisymmetric surface.
The method for manufacturing a mold according to claim 5, wherein the test processing is performed on a material different from a material of the mold.
The molding die has, as the plurality of optical transfer surfaces, a plurality of types of optical transfer surfaces having different design values of expressions of the axially symmetric surfaces,
The expression for 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 optical axes parallel to each other, and the plurality of optical transfer surfaces are processed by a tool having a rotation axis parallel to the optical axis. The manufacturing method of the shaping | molding die of description.
The method for manufacturing a molding die 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 equation.
A method for producing a lens array, comprising a step of molding using a mold obtained by the mold production method according to any one of claims 1 to 9.