JP6296679B2 - Microlens array manufacturing method and diffusion plate manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a diffusion plate having a microlens array.
In particular, in fields where light needs to be controlled by condensing, diffusing, reflecting, etc., such as displays, cameras, measuring instruments, etc., such as manufacturing methods of optical elements that require microlenses, especially viewfinders such as single lens reflex cameras. The present invention relates to a method for manufacturing a diffusion plate used in a system.

Conventionally, as a manufacturing method of a transfer prototype for forming a microlens array, in the manufacturing method described in Patent Document 1, a photosensitive resin is formed into a predetermined shape and has a large number of irregularities using a photomask. There is a manufacturing method using a so-called photolithography method for forming a fine pattern.
Further, a cutting tool having a cutting edge contour shape that is the same as the contour shape in a cross section perpendicular to either one of the center lines that pass through the center of the lens surface to be formed as described in Patent Document 2 is used as the lens surface. On the other hand, it is moved along the same locus as the contour shape in the cross section perpendicular to the other center line. Then, a manufacturing method using a so-called cutting method is disclosed, in which a lens surface is formed on the workpiece, and the workpiece is linearly moved in a direction parallel to the trajectory of the cutting tool to produce a transfer master. Has been.

Japanese Patent No. 2698218 Japanese Patent No. 4213897

However, the diffusion plate having the microlens array by the manufacturing method described in Patent Document 1 has the following problems.
In the manufacturing method using photolithography, it is difficult in principle to control the shape below the resolution of the exposure system. Therefore, it is difficult to sharply control the edge of the ridge line connecting adjacent microlenses.
In addition, a diffusion plate having a microlens array made from a transfer prototype having a lens transfer surface (shape) for forming a microlens by the manufacturing method described in Patent Document 2 has the following problems. Yes.
A plurality of transfer prototypes having lens transfer surfaces (shapes) for forming a microlens array are two-dimensionally arranged so that the lens transfer surfaces (shapes) partially overlap. In the case of forming a plurality of lens transfer surfaces in a two-dimensionally overlapping manner on the workpiece (mold), the lens transfer surface on which the tool is cut into the workpiece (already processed lens transfer surface) ) Direction. Therefore, the workpiece material that has been cut and removed is pushed out toward the processed lens transfer surface, and the ridge line edge of the processed lens transfer surface is plastically deformed.

  In view of the above problems, the present invention can sharply form a ridge line edge of a transfer prototype having a lens transfer surface (shape) for molding a microlens. Therefore, an object of the present invention is to provide a method of manufacturing a diffusion plate having a microlens array in which the edge of a microlens ridge line is sharply formed and has excellent diffusion performance and appearance quality.

The method of manufacturing a microlens array of the present invention is a method of manufacturing a microlens array in which a plurality of microlenses are arranged so as to partially overlap, and a tool having a rake face including an arcuate cutting edge ridge line is processed. A machining step of machining a concave shape on the surface of the workpiece by moving in a direction intersecting the surface intersecting with the edge of the cutting edge while making a reciprocating motion in a plane intersecting the edge of the cutting edge relative to the object After the processing step, the processing step is further continued, and the second concave shape is processed in a direction intersecting with the surface intersecting with the edge of the cutting edge so as to overlap a part of the concave shape. Then, the tool is moved to the rake face side in a direction intersecting the edge of the cutting edge, and the machining step is performed so that the concave shape part and the second concave shape part overlap. Third concave shape Processed to and forming a plurality of concave shape.
The manufacturing method of the diffusing plate of the present invention is manufactured using the manufacturing method of the microlens array.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the diffusion plate which has the micro lens array which can form a micro lens ridgeline edge sharply, and was excellent in the diffusion performance and the external appearance quality is realizable.
Furthermore, according to the manufacturing method of the diffusing plate having the microlens according to claim 3, the microlens is a curved surface or the tool in which the edge edge of the tool is continuously connected to the chord winding in the normal direction. Is a curved surface formed by continuously connecting the cutting edge ridge lines in a direction to maintain a constant posture with respect to the workpiece.
Therefore, the contour shape formed in the workpiece surface is a substantially elliptical curved surface shape, and the substantially elliptical curved surface shape is unambiguous depending on the motion condition for setting the arcuate shape of the cutting edge ridge line of the tool and the chord winding that is the movement locus of the tool. Defined in Here, since the processing feed for forming a plurality of microlenses is a reciprocating raster scan, the traveling direction of the chord winding is two directions, that is, the forward path and the return path, so the substantially elliptic curved surface is also defined in two types. It will be. Therefore, it is possible to form a microlens array in which two types of microlenses are alternately arranged in the pick feed direction of the processing feed.
In the diffusion plate manufactured using the microlens array formed in this way as a transfer prototype, the bright spot interval of the diffusion distribution becomes narrow. For this reason, the number of bright spots that can be seen increases, and the brightness of each bright spot becomes weaker in proportion to the number of bright spots. As a result, the bright spots become inconspicuous and natural blurring is obtained. .
Moreover, according to the manufacturing method of the diffuser plate having the microlens according to claims 4 and 5, the angular velocity of the circular motion is controlled, or the direction of the machining feed is controlled relative to the circular motion surface. Since the shape of the microlens can be intentionally controlled and the light intensity distribution for each diffusion angle can be adjusted, the effect of expanding the degree of freedom of design related to the brightness of the blurred image can be obtained.
Moreover, according to the manufacturing method of the diffusion plate which has the micro lens of Claim 6, the angle which controls the direction of a process feed relatively with respect to a circular motion surface is computable in a short time.
Therefore, since the shape of the microlens can be controlled to have a desired anisotropy with little anisotropy, there is an effect that the optical characteristics of the diffusion plate can be made as designed.

It is the schematic diagram which showed the 1st step in Embodiment 1 of this invention. It is the schematic diagram which looked at the 1st step in Embodiment 1 of the present invention from the processing feed direction, (a) is a schematic diagram at the time of maintaining a tool posture in a fixed direction, (b) is a tool posture in a circular motion. It is a schematic diagram at the time of keeping it to a fixed attitude | position with respect to a normal line direction with respect to it. It is the schematic diagram which showed the 2nd step in Embodiment 1 of this invention, (a) is sectional drawing of the to-be-processed object which formed the micro lens array, (b) is sectional drawing which showed the formation process, (c) ) Is a cross-sectional view of a diffusion plate having a microlens array. It is the schematic diagram which showed the apparatus structure which implement | achieves Embodiment 1 of this invention, (a) is a front view (b) is a side view. It is the schematic diagram which showed the 2nd and 3rd step of Embodiment 2 of this invention, (a) is sectional drawing of the to-be-processed object which formed the microlens array, (b) is a to-be-processed object with a transfer prototype. (C) is a cross-sectional view of a transfer process using the transfer product obtained in (b) as a transfer prototype, (d) is a cross-sectional view of a replication mold obtained in the process of (c), (E) is sectional drawing of the shaping | molding process which used the replication type | mold as the transcription | transfer prototype, (f) is sectional drawing of the diffusion plate which has a microlens array. It is the figure which plotted the cross-sectional shape of the diffusion plate in Embodiment 1 of this invention. It is the schematic diagram which looked at the 1st step in Embodiment 3 of the present invention from the upper part, (a) is an upper surface figure at the time of an outward process, and (b) is an upper surface figure at the time of a backward process feed. It is a simulation figure of the diffusion plate in Example 3 of this invention, (a) is a schematic diagram of surface shape, (b) is a schematic diagram of a diffusion characteristic. It is the schematic diagram which looked at the 1st step in Embodiment 4 of the present invention from the upper part, (a) is a top view of the 1st step of Embodiment 1 as a comparative example, (b) is the 1st of Embodiment 4. It is a top view of the step. It is the schematic diagram of the 1st step in Example 1 of this invention, (a) is a schematic diagram of the waveform signal input into a Z-axis, (b) is a schematic diagram of the waveform signal input into a X-axis, (c). These are schematic views seen from the machining feed direction. It is the schematic diagram of the 1st step in Example 4 of this invention, (a) is a schematic diagram of the waveform signal input into a Z-axis, (b) is a schematic diagram of the waveform signal input into a X-axis, (c). These are schematic views seen from the machining feed direction. It is the schematic diagram which looked at the 1st step in Embodiment 5 of the present invention from the upper part, (a) is a top view of the 1st step of Embodiment 1 as a comparative example, (b) is the 1st of Embodiment 5. It is a top view of the step. It is the schematic diagram which showed the apparatus structure which implement | achieves Example 5 of this invention, (a) is a front view (b) is a top view. It is the schematic diagram which showed the difference shape from the spherical surface of the microlens shape of the diffusion plate in Example 5 of this invention. It is a simulation figure of the diffusion plate concerning the prior art of this invention, (a) is a schematic diagram of surface shape, (b) is a schematic diagram of a diffusion characteristic.

The manufacturing method of the diffusion plate having the microlens array of the present invention, as described above, uses a tool having an arcuate cutting edge ridge line to the cutting edge ridge line of the tool with respect to a workpiece to be a transfer prototype of the diffusion plate. While repeating the orbiting motion in the intersecting plane, the process feed is performed in the direction intersecting the orbiting motion surface to form a lens transfer surface (shape) for forming a plurality of microlenses on the surface of the workpiece. Provide a process. As a result, the lens transfer surface (shape) is a curved surface continuously connecting the cutting edge ridge line of the tool to the chord winding in the normal direction or the cutting edge ridge line of the tool in a constant posture with respect to the workpiece. It is formed in a shape having a curved surface continuously connected in the direction to be maintained.
Therefore, the contour shape formed in the workpiece surface is a substantially elliptical curved surface shape, and the substantially elliptical curved surface shape is unambiguous depending on the motion condition for setting the arcuate shape of the cutting edge ridge line of the tool and the chord winding that is the movement locus of the tool. Defined in
Embodiments and examples of the present invention will be described below with reference to the drawings.

[Embodiment 1]
As Embodiment 1, a workpiece having a plurality of lens transfer surfaces (shapes) for forming a microlens array is transferred to a resin or the like as a transfer prototype, and a method for manufacturing a diffusion plate having a microlens array An example will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the first step of this embodiment.
In FIG. 1, 1 is a lens transfer surface, 2 is a workpiece, 3 is a tool, 4 is a circular motion, and 5 is a machining feed.
In the first step of the present embodiment, a tool having an arcuate cutting edge ridge line is moved around in a plane intersecting a tool rake face that is a surface having a cutting edge ridge line, while the tool rotating movement surface is moved. A lens transfer surface is formed on the workpiece by feeding the workpiece in the intersecting direction. Further, by continuously performing the processing feed, a plurality of two-dimensionally arrayed lens transfer surfaces are partially overlapped to form a transfer master for forming a microlens array.
The shape of the lens transfer surface obtained by the present embodiment will be described with reference to FIGS. 2 (a) and 2 (b).
As shown in the schematic diagram showing the first step viewed from the machining feed direction in FIG. 2A, it consists of a circular motion and a machining feed in a direction that keeps the edge edge of the tool in a constant posture with respect to the workpiece. A curved surface continuously connected on the string winding, which is an actual tool locus, is defined as a lens transfer surface. Alternatively, as shown in the schematic diagram of FIG. 2 (b), a curved surface formed by continuously connecting the cutting edge ridge line of the tool continuously in the normal direction to the chord winding that is an actual tool trajectory composed of a circular motion and a machining feed. The transfer surface.

Next, a mode for carrying out the second step described in claim 1 of the present invention will be described with reference to FIG.
FIG. 3 is a schematic view showing an example of the second step in the present invention. FIG. 3A is a cross-sectional view of a workpiece on which a plurality of lens transfer surfaces are formed by the first step, and FIG. ) Is a cross-sectional view of a molding process in which a workpiece is used as a transfer prototype, and the shape is transferred to the workpiece. FIG. 3C has a microlens array, which is a workpiece after the shape of the transfer prototype is transferred. A sectional view of the diffusion plate is shown.
A workpiece on which a plurality of lens transfer surfaces are formed in the first step is used as a transfer master, and is incorporated into a molding die for transferring the shape. Taking injection molding as an example, a thermoplastic resin heated to a temperature to be softened as a transfer object is pressed into a cavity inside a molding die by applying injection pressure, and the mold is filled with the shape of the transfer prototype. Copy it.

Example 1
In Example 1, a microlens array having a lens R of 15 μm and a distance between lens vertices of 7.5 μm was manufactured. FIGS. 4A and 4B are schematic views showing a device configuration for carrying out the first step according to claim 1.
First, a method for forming a lens transfer surface, which is the first step of the first embodiment, will be described. In this embodiment, devices and jigs generally similar to ultra-precision machining were prepared. The tool 3 is a diamond tool that has a sharp edge and provides high-precision work transferability, and has a R15 μm arc-shaped cutting edge ridge line.
Moreover, the material of the to-be-processed object 2 selected as a process layer the copper-type material considered that the machinability with a diamond bite is good. The processing machine is a high-precision processing machine that can command cutting on a submicron order, and has a configuration including a Z-axis moving table 13 and an XY-axis moving table 14. A high-speed orbiting motion device 12 was used as a device for imparting orbiting motion to the tool. In this embodiment, a magnetostrictive vibrator is used as a driving source for the circular motion.
Two magnetostrictive vibrators were arranged in an orthogonal direction in a high-speed orbiting motion device, and the reciprocation of each was controlled by an arbitrary waveform generator 15 to realize a round locus of R15 μm. As a waveform condition, a condition for synchronizing two sine waves having an amplitude of 30 μm and a frequency of 880 Hz with a phase difference corresponding to a quarter wavelength was selected. The machining feed rate was 6.6 mm / s.
By defining the above circular motion and machining feed conditions, the tool movement trajectory is uniquely determined and a string winding is drawn. The workpiece was processed with a depth of cut of 1 to 5 μm. A transfer prototype having a plurality of lens transfer surfaces was obtained.

Next, a diffusion plate having a microlens array is obtained by using a general injection molding method as a transfer process, which is the second step of this embodiment, and pouring and transferring a resin to a transfer master having a plurality of lens transfer surfaces. Got.
A general polymethyl methacrylate resin was used as an optical element material for an object to be transferred serving as a diffusion plate. Using the first and second steps as described above, a diffusion plate having a cross-sectional profile of the microlens array shown in FIG. 5 was obtained.
As shown in FIG. 5, the microlens of the diffusion plate obtained by this example has a sharp ridge line edge.
As a result, the viewfinder image of the single-lens reflex camera using the diffuser plate according to the present embodiment has a sharp ridgeline portion and a sharp shape, and has a strong effect of diffusing light rays. For this reason, an effect that the focus position can be easily grasped is obtained by the fact that the difference in the degree of blur of the finder image is larger than that at the time of focusing because the light beam at the time of defocusing is strongly diffused.

[Embodiment 2]
As a second embodiment, a configuration example of a manufacturing method of a diffusion plate having a microlens array that is different from the first embodiment will be described with reference to the drawings.
In the manufacturing method of the diffusion plate having the microlens array of this embodiment, the first step is the same as that of the first embodiment, and the second and third steps are different from those of the first embodiment as will be described next. .
Next, the second and third steps of this embodiment will be described with reference to the schematic diagram of FIG. In FIG. 6, 10 is a replication type convex, and 11 is a replication type concave.
FIG. 6A is a cross-sectional view of a workpiece on which a plurality of lens transfer surfaces are formed in the first step, and FIG. 6B is a reverse plurality of convex lens transfers using the workpiece as a transfer prototype. It is sectional drawing of the transcription | transfer process which obtains the replication type | mold convex which has a surface.
FIG. 6C is a cross-sectional view of a transfer process for obtaining a replication type concave having a plurality of concave lens transfer surfaces having a reverse shape from a replication type having a plurality of convex lens transfer surfaces, and FIG. It is sectional drawing of the replication type | mold concave which has the some lens transfer surface of the concave transferred by the process of FIG.6 (c).
FIG. 6E is a cross-sectional view of the molding process in which the replication concave is used as a transfer master and the shape is transferred to the transfer object. FIG. 6F is the transfer object after the replication recess is transferred. It is sectional drawing of the diffusion plate which has a micro lens array.

The second step of the present embodiment is a step of replicating the workpiece on which the plurality of lens transfer surfaces are formed in the first step into the shape of the transfer prototype.
Using a transfer method using electroforming, a process of copying the shape of the transfer master onto the transfer object (first transfer object) is performed to obtain a replication-type protrusion having a convex lens transfer surface with an inverted shape. By obtaining a transfer product again by electroforming, a replication-type concave having a concave lens transfer surface can be obtained. By repeating the above steps, a plurality of replication molds can be obtained from one transfer prototype.
A diffusion plate having a microlens array can be obtained by incorporating the obtained replication mold into a molding die and transferring the shape to a resin (second transferred material) in the same manner as described above.
The shape of the replication type lens transfer surface obtained by repeating this step a plurality of times can be either concave or convex.

(Example 2)
In Example 2, as in Example 1, the lens R is 15 μm, and the distance between the lens vertices is 7.5 μm.
A diffusion plate having a microlens array such that m is obtained was manufactured. In the first step, the same method as in the second step described in Example 1 was used to obtain a transfer prototype having a plurality of lens transfer surfaces arranged at equal intervals.

  The second step is a step of duplicating the shape of the transfer prototype obtained in the first step. In this embodiment, a duplication method using electroforming is used. The shape of the transfer prototype obtained in the first step was transferred to obtain a duplicated convex having a convex lens transfer surface. Furthermore, a replication-type recess having a concave lens transfer surface was obtained by transferring a replication-type shape having a convex lens transfer surface. By repeating the above steps, it is possible to obtain a plurality of replica molds from one transfer prototype, and to obtain a replica mold having either concave or convex lens transfer surfaces.

[Embodiment 3]
As a third embodiment, a configuration example of a manufacturing method of a diffusion plate having a microlens array will be described with reference to FIG.
The third embodiment is different in a part of the first step described in the first and second embodiments, and the second step and the third step are the same as the first and second embodiments. is there.
First, the first step will be described with reference to the schematic diagram of FIG.
FIG. 7 (a) is a schematic view of machining as viewed from the upper surface when the tool is performing forward scanning when the machining feed in the present invention is reciprocating raster scanning, and FIG. The process schematic diagram seen from the upper surface is shown.
In FIG. 7, 1 is a lens transfer surface, 2 is a workpiece on which the lens transfer surface is processed, and 3 is a tool having an arcuate cutting edge ridge line for processing the lens transfer surface on the workpiece. When the machining feed to be sent in the direction intersecting the circumferential motion surface of the tool is reciprocating raster scanning, the forward machining feed is 16 and the backward machining feed is 17, and the relative tool trajectory to the workpiece is 18.
A tool having an arcuate cutting edge ridge line is revolved in the direction intersecting the tool rake surface, which is the surface having the cutting edge ridge line, while being fed in a direction that intersects the tool circumferential movement surface. Microlenses are formed on the workpiece.

An example of the lens transfer surface obtained by the first step will be described with reference to FIG.
FIG. 2 also shows a schematic view of the first step in the third embodiment viewed from the machining feed direction. 2A is a schematic diagram when the tool posture is maintained in a fixed direction, and FIG. 2B is a schematic diagram when the tool posture is maintained in a normal direction in a normal direction with respect to the orbiting motion. It is.
When the tool posture is maintained in a certain direction as shown in FIG. 2A, the actual tool trajectory consisting of circular motion and machining feed in a direction to keep the tool edge ridge line in a constant posture with respect to the workpiece. A lens transfer surface having a curved surface continuously connected on the string winding is formed.
In addition, when the tool posture is kept constant in the direction normal to the orbiting motion as shown in FIG. 2B, the cutting edge ridge line of the tool is actually made up of the orbiting motion and the machining feed. A lens transfer surface having a curved surface continuously connected in the normal direction to the string winding as the tool locus is formed.

According to these, by repeating the circular motion with respect to the machining feed, the actual tool trajectory draws a string winding, and a plurality of lens transfer surfaces can be formed continuously on the workpiece. Further, when forming a shape in which a plurality of lens transfer surfaces are two-dimensionally arranged on the workpiece surface, a plurality of lens transfer surfaces can be formed by reciprocating raster scanning of the processing feed.
At that time, there are two directions of forward path feed and backward path feed, and the tool trajectory to be drawn is also determined in two directions with respect to the workpiece.
The tool trajectory during the forward machining feed becomes a unique chord winding depending on the conditions of the orbiting motion and the machining feed. If the machining feed speed and the angular velocity of the orbiting motion are constant, as shown in FIG. When the locus is projected upward, a sinusoidal curve is obtained.
In FIG. 7B, the tool trajectory projected upward is a sine curve as in FIG. 7A, but the direction of machining feed is different.
As described above, since the lens transfer surface in the present embodiment is uniquely defined by the cutting edge edge line of the tool and the tool trajectory, two types of lens transfer surfaces corresponding to processing feed in two directions of the forward path and the return path are formed. A microlens array obtained by transferring this has a microlens array in which a plurality of two types of microlenses are arranged.

(Example 3)
Next, an example of the diffusion plate obtained by the present embodiment will be described with reference to FIG. FIG. 8A is a diagram showing the height direction of the shape of the diffusion plate in gray scale, and FIG. 8B is a diagram showing a simulation result of the diffusion characteristics of the diffusion plate in FIG. 8A.
FIG. 15 is a view showing an example of a diffusion plate obtained by the prior art as a comparison. FIG. 15A is a diagram showing the height direction of the simulation shape of the diffusion plate in gray scale, and FIG. ) Is a diagram showing a simulation result of the diffusion characteristics of the diffusion plate in FIG.
Compared with the diffusion plate obtained by the prior art, the diffusion plate in the present embodiment has two different types of microlenses arranged with periodicity, and has a different period from the microlens array in which one type of microlens is arranged. Sex can be obtained.
For this reason, the bright spot interval of the diffusion distribution is narrowed, the number of bright spots that can be seen relatively increases, and the brightness of each bright spot also decreases in proportion to the number of bright spots, so that the resulting bright spot becomes inconspicuous.
As a result, the finder image of the single-lens reflex camera using the diffusion plate according to the present embodiment can obtain an effect that the blur is natural.
As a result, the number of bright spots that can be seen increases and the brightness of each bright spot decreases in proportion to the number of bright spots. As a result, the bright spots become inconspicuous, and natural blurring can be obtained. Become. In addition, by using reciprocating raster scanning as the processing feed, it is possible to perform processing in about a half of the processing time of one-way scanning.

[Embodiment 4]
As a fourth embodiment, a configuration example of a manufacturing method of a diffusion plate having a microlens different from the first and second embodiments will be described with reference to the drawings.
The fourth embodiment is different from the first step described in the first and second embodiments in some forms, and the second step and the third step are the same as the first and second embodiments. is there.
In the first step of the present embodiment, a tool having an arcuate cutting edge ridge line is moved around in a plane intersecting a tool rake face that is a surface having a cutting edge ridge line, while the tool rotating movement surface is moved. A lens transfer surface is formed on the workpiece by feeding the workpiece in the intersecting direction.

FIG. 9B shows an example of the first step according to the present embodiment. FIG. 9A is a schematic diagram of the first step of the first embodiment, and is shown as a comparative example with the present embodiment.
As described above, if the angular velocity ωa of the circular motion and the machining feed are constant, the tool trajectory is a unique chord winding, and the projection curve is a sine curve as shown in FIG. Therefore, the tool trajectory has a predetermined angle θa with respect to the center line of the lens transfer surface.
θa is uniquely determined by the angular velocity ωa of the circular motion and the machining feed rate.
The present embodiment is characterized in that the angular velocity of the circular motion is intentionally controlled so as to draw a tool trajectory as shown in FIG. 9B. In FIG. 9B, the angular velocity ωb of the circular motion when the tool forms the lens transfer surface is controlled so that ωb> ωa under the constant processing feed speed condition.
By doing so, the rotational speed of the tool when forming one lens transfer surface is increased, and the cycle of the sinusoidal curve onto which the tool trajectory is projected is faster than in FIG. Therefore, a tool locus is drawn such that the angle θb with respect to the center line of the lens transfer surface satisfies θb <θa.

Next, control of the interval between adjacent lens transfer surfaces will be described.
The interval between adjacent lens transfer surfaces is determined by the length of one cycle of the circular motion under the condition that the processing feed rate is constant.
Therefore, by controlling the angular velocity of the orbiting motion during idling while the tool forms the next lens transfer surface adjacent to each other so that the length of one cycle of the orbiting motion is the same as that when the angular velocity ωa is constant, The interval between adjacent lens transfer surfaces is set to be the same as the constant angular velocity ωa.
The shape of the lens transfer surface obtained by this embodiment is determined by the angular velocity of the circular motion and the processing feed speed when forming the lens transfer surface, and the shape of the lens transfer surface also changes as each motion condition is changed. As a transfer prototype with this lens transfer surface, a diffuser plate with microlenses obtained by transferring it to a resin or the like can intentionally control the shape of the microlens and adjust the intensity distribution of light rays for each diffusion angle Therefore, the degree of freedom in optical design that makes the brightness of the blurred image a desired value can be widened.

Example 4
In Example 4, a diffusion plate having a microlens array was manufactured by applying the manufacturing method of Embodiment 4.
FIGS. 11A, 11B, and 11C are schematic views showing the circular motion and the control waveform thereof in the first step of the fourth embodiment. FIG. 10 is a schematic diagram of the first step of the first embodiment, and is shown as a comparative example with the present embodiment.
The control method of the orbital motion is a high-speed orbital motion apparatus in which two drive sources are arranged in an orthogonal direction, and sets a condition for synchronizing each reciprocating movement with a phase difference corresponding to a quarter wavelength of two waveform signals. A circular motion that draws a perfect circular locus was realized.
The lens transfer surface is formed at the timing when the tool and the workpiece interfere with each other in the circular motion of the tool, and at this time, the frequency of the two waveform signals input from the arbitrary waveform generator is controlled. Thus, the angular velocity of the orbital motion was intentionally adjusted.

Next, an example of the waveform condition of the circular motion will be specifically described.
The vibration waveform shown in FIG. 11A is an arbitrary waveform in which the frequency of the sine wave is largely controlled at the timings c ′ and d ′ at which the lens transfer surface is formed. The embodiment shown in FIG. Compared with the circular motion condition with a constant angular velocity in 1, the frequency at the time of forming the lens transfer surface was controlled twice.
Similarly, in FIG. 11B, at the timings c ′ and d ′ at which the lens transfer surface is formed, control is performed so that the frequency becomes twice as high as the orbiting motion condition in the first embodiment. The angular velocity of movement was adjusted to double.
Further, in order to make one cycle of the circular motion the same as that in the first embodiment, the frequency is two-thirds that of the first embodiment at the timing of a ′ and b ′ when the non-lens transfer surface is formed. By controlling, it adjusted so that it might become the same period as the circular motion with constant angular velocity of Example 1.
The waveform signal under the above conditions was input to each drive source of the high-speed orbiting motion apparatus, the machining feed rate was set to 6.6 mm / s as in Example 1, and reciprocating raster scanning was performed.

By determining the circular motion condition and the machining feed condition as described above, the tool movement trajectory is determined by a unique string winding.
As shown in the schematic diagram of FIG. 9, the angle θ formed by the curved line projected on the chord winding tool movement locus and the center line of the lens transfer surface changes in accordance with the angular velocity ω of the circular motion when the microlens is formed. To do.
In this embodiment, the angular velocity ω is controlled to be twice that of the first embodiment, so that the angle θ formed by the projection curve of the tool movement locus and the center line of the microlens decreases accordingly. Further, since one cycle of the circular motion is the same and the processing feed rate is the same, a plurality of lens transfer surfaces arranged at equal intervals with a lens interval of 7.5 μm were processed. Thereafter, the first step and the second step subsequent to the return path machining were performed in the same manner as in Example 1.
The microlens of the diffusion plate obtained by this example has a shape with a small difference from the spherical component as compared with Example 1. Thereby, the intensity distribution of the light beam for each diffusion angle becomes a value corresponding to the shape of the microlens, so that the brightness of the blurred image can be set to a desired optical characteristic.
The control method of the circular motion in the present embodiment is an example, and the type is not limited as long as it is a means that can intentionally adjust the angular velocity.

[Embodiment 5]
As a fifth embodiment, a configuration example of a manufacturing method of a diffuser plate having microlenses different from the first and second embodiments will be described with reference to the drawings.
In the fifth embodiment, a part of the first step described in the first and second embodiments is different. The second step and the third step are the same as those in the first and second embodiments. is there.
FIG. 12B shows an example of the first step of the present embodiment. FIG. 12A is a schematic diagram showing an example of the first step of the first embodiment, and is shown as a comparative example with the present embodiment. In FIG. 12, 19 indicates a circular motion direction vector in the projection curve of the relative tool locus, 20 is a machining feed direction vector, and 21 is a direction that linearly defines the relative tool locus projection curve when the lens transfer surface is formed. , 19 and 20 are combined into a vector.

In the first step of the present embodiment, a tool having an arcuate cutting edge ridge line is moved around in a plane intersecting a tool rake face that is a surface having a cutting edge ridge line, while the tool rotating movement surface is moved. A lens transfer surface is formed on the workpiece by feeding the workpiece in the intersecting direction.
As described above, assuming that the angular velocity of the orbiting motion and the machining feed are constant, and the angle formed by the orbiting motion surface and the machining feed is vertical, the tool trajectory is a unique chord winding, and the projection curve is shown in FIG. It becomes such a sine curve.
Therefore, the tool trajectory has a predetermined angle θc with respect to the center line of the lens transfer surface. θc is uniquely determined by the angular velocity of the orbiting motion and the speed of the machining feed and the angle formed by the orbiting motion surface and the machining feed.

This embodiment is characterized in that the angle of the circular motion with respect to the machining feed is intentionally controlled so as to draw a tool trajectory as shown in FIG.
Under a constant processing feed speed condition, in FIG. 12B, the angle θe formed by the circumferential motion surface and the processing feed when the tool forms the lens transfer surface is θe <90 ° in FIG. 12A. It is controlled to become.
By doing so, the circular motion direction vector when forming the lens transfer surface becomes a direction including a minus component with respect to the processing feed direction.
Therefore, by canceling the machining feed direction vector by the amount of the negative component, as a result, an angle θd formed by the combined vector and the center line of the lens transfer surface in the present embodiment draws a tool locus such that θd <θc.
The shape of the lens transfer surface obtained according to the present embodiment is determined by the angle formed by the circular motion surface and the processing feed at the time of forming the lens transfer surface, and the shape of the lens transfer surface also changes as each motion condition is changed.
As a transfer prototype with this lens transfer surface, a diffuser plate with microlenses obtained by transferring it to a resin or the like can intentionally control the shape of the microlens and adjust the intensity distribution of light rays for each diffusion angle Therefore, the degree of freedom in optical design that makes the brightness of the blurred image a desired value can be widened.

(Example 5)
In Example 5, a diffusion plate having a microlens array was manufactured by applying the manufacturing method of Embodiment 5. FIGS. 13A and 13B are schematic views showing an apparatus configuration for carrying out the first step in the fifth embodiment. FIG. 13A is a front view, and FIG. 13B is a top view. Indicates.
First, as a means for realizing the circular motion, in this embodiment, two vibration devices are arranged in the orthogonal direction, and the vibration device placed on the Z-axis movement table is the tool vibration device 22, the XY-axis movement table. The vibration device placed on the workpiece is referred to as a workpiece vibration device 23.
In this example, similarly to the control means for the circular motion described in the first example, each reciprocating movement was controlled by the arbitrary waveform generator 15 for the amplitude, period, phase, etc., and the circular motion was realized. In order to control the angular direction of the orbiting surface, in this configuration, the workpiece vibration device 23 placed on the XY-axis moving table is tilted by a predetermined angle with respect to the machining feed.
The angle formed by the orbiting motion surface with respect to the machining feed was set to a value calculated based on the orbiting motion period and the orbiting motion radius.

Next, the shape of the microlens of the diffusion plate formed using the above-described means will be described. FIG. 14B is a diagram showing the difference from the spherical surface in the shape of the microlens in Example 5 in gray scale, and FIG. 14A is the gray difference in the shape of the microlens in Example 1 from the spherical surface. It is the figure represented with the scale, and shows as a comparative example with a present Example.
As shown in FIG. 14B, the shape of the microlens in the present embodiment can be controlled so that the asphalt component is equal to that in the first embodiment.
The diffuser plate obtained by this embodiment can intentionally control the shape of the microlens and can adjust the intensity distribution of the light beam for each diffusion angle, so that the brightness of the blurred image can be adjusted to a desired value. A range of degrees of freedom can be provided.
Furthermore, the angle for controlling the direction of machining feed relative to the orbiting motion surface can be calculated in a short time. Therefore, since the shape of the microlens can be controlled to have a desired anisotropy with little anisotropy, there is an effect that the optical characteristics of the diffusion plate can be made as designed.

In addition, the control method of the angle formed by the orbiting motion surface and the machining feed in this embodiment is an example, and the type is not limited as long as the angle can be adjusted intentionally.
For example, you may implement | achieve by attaching the apparatus made to drive a circular motion incline with respect to a process feed.
The material of the workpiece in the present invention is not limited to the copper-based material used in the first embodiment, and a material suitable for precision cutting such as an aluminum-based material or an electroless nickel-based material can be used.
Further, the circular motion in the present invention is not limited to the high-speed circular motion device using the magnetostrictive vibrator used in the first embodiment, and a moving mechanism of a processing machine, a piezoelectric element, an ultrasonic oscillator, or a combination thereof may be used. The mechanism is not limited to this type as long as it can be driven around. At this time, electrical control using an arbitrary waveform generator is performed for the control, and the present invention is not necessarily limited to the condition for controlling the perfect circular locus.
For example, free control such as changing the amplitude, period, phase, etc. during machining, or stopping the movement is also possible.

Further, as shown in FIG. 2B, the posture of the tool may be controlled so as to be constant in the normal direction with respect to the chord winding that is an actual tool trajectory composed of the circular motion and the machining feed. For example, the tool may be rotated.
Similarly, the processing feed can be freely controlled not only in general reciprocating raster scanning, in which the speed and direction are changed during processing.
Furthermore, the method for transferring the shape of the transfer pattern in the present invention is not limited to the injection molding method, and any process can be used as long as it can transfer the shape of the transfer pattern. For example, nanoimprint or compression molding may be used.

1: Lens transfer surface 2: Work piece 3: Tool 4: Circumferential movement 5: Work feed 6: Transfer master 7: Mold for molding 8: Transfer object 9: Diffusion plate 10: Duplicate mold convex 11: Duplicate mold concave 12: High-speed orbiting motion device 13: Z-axis movement table 14: XY-axis movement table 15: Arbitrary waveform generator 16: Outward machining feed 17: Backward machining feed 18: Relative tool trajectory 19: Orbital motion direction vector 20: Machining feed direction Vector 21: Relative tool trajectory direction vector 22: Tool vibration device 23: Workpiece vibration device

Claims (7)

A method of manufacturing a microlens array in which a plurality of microlenses are arranged so that a part thereof overlaps,
A tool having a rake face including an arcuate cutting edge ridge line is moved in a direction crossing the surface intersecting the cutting edge ridge line while rotating around the surface intersecting the cutting edge ridge line relative to the workpiece. A processing step of processing a concave shape on the surface of the workpiece,
After the processing step, further continue the processing step, after processing the second concave shape in a direction intersecting the surface intersecting the cutting edge ridge line so as to overlap a part of the concave shape,
The tool is moved to the rake face side in a direction intersecting the edge of the cutting edge and the machining step is performed, so that the third part is overlapped with a part of the concave shape and a part of the second concave shape . A method of manufacturing a microlens array, wherein a plurality of concave shapes are formed by processing a concave shape.   2. The method of manufacturing a microlens array according to claim 1, wherein the plurality of concave shapes are transferred to form a microlens array.   The plurality of concave shapes are transferred to form a replica mold having a plurality of convex shapes, the replica mold having the plurality of convex shapes is transferred to form a replica mold having a plurality of concave shapes, and the plurality of concave shapes 2. The method of manufacturing a microlens array according to claim 1, wherein the microlens array is formed using a replica mold having a shape.   The circular motion is controlled so that the angular velocity ω1 when the tool forms a concave shape on the workpiece and the angular velocity ω2 when the tool is not formed are different from each other in one cycle of the circular motion. The method of manufacturing a microlens array according to any one of claims 1 to 3. The direction crossing the cutting edge and the intersecting face, producing a microlens array according to any one of claims 1 to 4, characterized in that a direction perpendicular to the plane that intersects the cutting edge. 5. The method of manufacturing a microlens array according to claim 1, wherein a direction intersecting with a surface intersecting with the edge of the cutting edge is calculated from a period and a displacement of the circular motion.   A diffusion plate manufacturing method manufactured using the microlens array manufacturing method according to claim 1.