JP2014104563A - Method for machining lenticular-curved-surface array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for machining a lenticular-curved-surface array capable of machining a plurality of lenticular-curved-surface shapes to a curved surface workpiece while securing uniform machining accuracy.SOLUTION: A method for machining a lenticular-curved-surface array comprises processes of: (1) moving a tip of a tool to reference position coordinates of an initial lens shape and adjusting a rotational axis of the tool so as to form a predetermined relative angle with an optical axis of the initial lens shape; (2) machining the initial lens shape while maintaining the rotational axis of the tool parallel to the optical axis based on relative position coordinates of the initial lens shape; (3) moving the tip of the tool to reference position coordinates of the next lens shape and adjusting the rotational axis of the tool so as to form the predetermined relative angle with an optical axis of the next lens shape; and (4) processing the next lens shape while maintaining the rotational axis of the tool parallel based on the relative position coordinates of the next lens shape.

Description

  The present invention relates to a processing method for a curved surface array for lenses, in which a plurality of curved surface shapes for lenses are processed on a curved workpiece by a rotary tool.

  The expansion of the digital camera market is advancing the die processing technology for aspheric lenses. Furthermore, in the past few years, a lens curved surface array (lens array) in which a plurality of lens curved surface shapes having an aspherical shape or a spherical shape are arranged has been attracting attention for the purpose of reducing the complexity of optical systems and costs.

  A processing method for creating a plurality of curved surface shapes for lenses by contouring a plurality of linear axes using a rotary tool in order to arrange (processing) a plurality of curved surface shapes for lenses on a linear or planar workpiece. Has been proposed (see Non-Patent Document 1). In addition, there has also been proposed a machining method for creating a plurality of curved surface shapes for lenses by rotating a rotary tool and a workpiece synchronously at the same rotational speed using a special machining device (see Patent Document 1).

JP 2008-238285 A

Masahiko Fukuda, “Latest Ultra Precision Machining Machines and Machining Examples”, Optotronics 29 (4). 172-176, 2010-04

  According to the inventor of the present invention, by arranging (processing) a plurality of curved surface shapes for lenses on a curved workpiece rather than a linear or planar workpiece, the light homogeneity and light condensing performance can be significantly improved. It has been found that the possibility of realizing a projector and a stepper capable of projecting at a short distance is increased.

  However, the processing method described in Non-Patent Document 1 or Patent Document 1 is a processing method for arranging (processing) a plurality of curved surface shapes for lenses on a linear or planar workpiece as described above. A plurality of curved surface shapes for lenses cannot be arranged (processed) on a workpiece. Specifically, even if the processing method is applied to processing a curved workpiece, it is difficult to obtain preferable optical characteristics because the processing quality uniformity of the curved surface shape for each lens is not good.

  The present invention has been created based on the above findings. An object of the present invention is to provide a method for processing a curved surface array for a lens that can process a plurality of curved surface shapes for a lens on a curved workpiece while ensuring uniform processing accuracy.

  The present invention relates to a method of processing a curved surface array for a lens that processes a plurality of curved surface shapes for a lens on a curved workpiece with a rotary tool, and each curved surface shape for a lens has a reference position coordinate and a relative position relative to the reference position coordinate. The processing method includes (1) moving the tip of the rotary tool to the reference position coordinate of the curved surface shape for the lens that is the first processing target, and rotating the rotary tool. Adjusting the axis so as to form a predetermined relative angle with the optical axis of the first curved surface shape for the lens, and (2) based on the relative position coordinates of the curved surface shape for the first lens, the rotational axis of the rotary tool The step of processing the curved surface shape for the lens by sequentially moving the tip of the rotary tool while maintaining it parallel to its own axial direction, and (3) the tip of the rotary tool is the next processing target. Len Adjusting the rotation axis of the rotary tool so as to form the predetermined relative angle with the optical axis of the curved surface shape for the next lens, and (4) the next lens. Based on the relative position coordinates of the curved surface shape for the lens, the curved surface shape for the lens is processed by sequentially moving the tip of the rotating tool while maintaining the rotation axis of the rotating tool parallel to the axial direction of the rotating tool itself. And a process for processing a curved surface array for a lens.

  According to the present invention, while the curved surface shape for each lens is processed, the rotation axis of the rotary tool is maintained at a predetermined relative angle with respect to the optical axis of the curved surface shape for the lens. In machining the shape, variations in the moving trajectory of the rotary tool, that is, the movement trajectory (machining trajectory) of the cutting edge are suppressed. As a result, it is possible to obtain a processing accuracy with less variation (uniform) between the plurality of curved surface shapes for lenses to be processed.

  The plurality of lens curved surface shapes naturally include three or more lens curved surface shapes. In that case, the steps (3) and (4) are sequentially repeated for each curved surface shape of the lens to be processed.

  In the present invention, the first lens curved surface shape and the next lens curved surface shape (and the subsequent lens curved surface shape) do not have to be the same. Even if they are different, processing accuracy with little variation (uniform) can be obtained. For example, it is possible to improve the optical characteristics of the entire curved lens array by actively changing the curvature of the curved surface shape for each lens in accordance with the distance from the light source.

  Specifically, for example, the workpiece has a same cross-section in a predetermined direction before processing the lens curved surface array. That is, the present invention can be applied to the processing of so-called cylindrical lens arrays.

  Specifically, for example, the rotary tool is a single crystal diamond end mill.

  The present invention is also a lens array processed by the processing method.

  According to the present invention, by the processing method, it is possible to obtain processing accuracy with less variation (uniformity) between a plurality of curved surface shapes for lenses, so that preferable optical characteristics can be obtained in the entire lens array.

  According to the actual verification by the present inventors, a lens array in which the absolute value of the surface roughness of each lens curved surface shape is 5 nmRa or less can be realized by the present invention. Here, “Ra” indicates arithmetic mean roughness, and is defined by JIS B0601.

  Further, according to the actual verification by the present inventors, a lens array in which the deviation of the surface roughness of the curved surface shape for each lens is ± 5 nmRa or less can be realized by the present invention.

  The present invention also provides a lens array mold (usually a mold) processed by the above processing method.

  According to the present invention, by the processing method, it is possible to obtain a processing accuracy with less variation (uniformity) among a plurality of curved surface shapes for lenses to be processed. Overall, favorable optical properties can be obtained.

  According to the actual verification by the present inventors, a lens array mold in which the absolute value of the surface roughness of the curved surface shape for each lens is 5 nmRa or less can be realized by the present invention.

  Further, according to actual verification by the present inventors, a lens array mold in which the deviation of the surface roughness of the curved surface shape for each lens is ± 5 nmRa or less can be realized by the present invention.

  In addition, the present invention is a mirror characterized by being processed by the processing method.

  According to the present invention, by the processing method, it is possible to obtain processing accuracy with less variation (uniformity) between the plurality of lens curved surfaces to be processed, so that preferable optical characteristics can be obtained over the entire mirror.

  According to the actual verification by the present inventor, according to the present invention, a mirror having an absolute value of the surface roughness of each lens curved surface shape of 5 nmRa or less can be realized.

  Further, according to the actual verification by the present inventor, according to the present invention, a mirror having a deviation in surface roughness of each lens curved surface shape of ± 5 nmRa or less can be realized.

  According to the present invention, while the curved surface shape for each lens is processed, the rotation axis of the rotary tool is maintained at a predetermined relative angle with respect to the optical axis of the curved surface shape for the lens. In the machining of the shape, variations in the movement trajectory of the rotary tool, that is, the movement trajectory of the cutting edge (processing trajectory) are suppressed. As a result, it is possible to obtain a processing accuracy with less variation (uniform) between the plurality of curved surface shapes for lenses to be processed.

It is the schematic which shows an example of the processing machine used with the processing method of the curved surface array for lenses of one embodiment of this invention. FIG. 2A is a perspective view of an example of a curved workpiece before the processing of the lens curved array. FIG. 2B is an enlarged cross-sectional view of a portion indicated by a symbol K in FIG. It is a figure for demonstrating an example of the process of processing the curved surface shape for the first lens. It is a figure for demonstrating an example of the process of processing the following curved surface shape for lenses. It is a figure which shows notionally the relationship between a macro program and a machining program. It is a figure which shows an example of a process program. It is a figure which shows an example of the movement track | route of a rotary tool in the process of the curved surface shape for each lens. FIG. 8A is a perspective view of an example of a curved workpiece after processing the curved lens array. FIG. 8B is a partially enlarged view of FIG. It is a figure for demonstrating the other example of the process of processing the curved surface shape for the first lens. It is a figure for demonstrating the other example of the process of processing the following curved surface shape for lenses. It is a figure which shows the other example of the movement track | route of a rotary tool in the process of the curved surface shape for each lens.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view showing a processing machine used in the method for processing a curved surface array for lenses according to an embodiment of the present invention.

  As shown in FIG. 1, a processing machine 10 used in the present embodiment includes a cast iron bed 11, an X-axis table 12 that is disposed on the bed 11 and is movable in the X-axis direction, and the bed 11. A Z-axis table 14 arranged and movable in the Z-axis direction, a column 13 fixed on the Z-axis table 14, a Y-axis arm 17 attached on the column 13 and movable in the Y-axis direction, and X A B-axis rotary table 15 mounted on the axis table 12 and rotatable around a B-axis parallel to the Y-axis, and a numerical controller 31 for controlling movement and rotation in each axis direction are provided.

  Specifically, the X-axis table 12, the Y-axis arm 17, and the Z-axis table 14 are linear guides using a finite VV rolling method, and are driven in the X, Y, and Z axis directions by a servo motor (linear motor). Each is driven linearly. Further, the X, Y, and Z axis position information of the X axis table 12, the Y axis arm 17, and the Z axis table 14 is respectively acquired by a high resolution optical scale (linear encoder) attached to each servo motor. ing.

  On the other hand, the B-axis rotary table 15 specifically has an aerostatic bearing as a rotary bearing, and is driven to rotate about the B-axis by a servo motor. Further, the B-axis angle information of the B-axis rotary table 15 is acquired by a high resolution optical scale (rotary encoder) attached to the servo motor.

  The control device 31 obtains X, Y, Z axis position information by each high-resolution optical scale and B axis angle information by the servo motor and applies feedback, while performing X, Y, Z axis linear drive by each servo motor and B The shaft rotation drive is controlled.

  The workpiece holder 16 is fixed on the B-axis rotary table 15, and the workpiece 20 to be processed is held by the workpiece holder 16.

  FIG. 2A is a perspective view of an example of the curved workpiece 20 before processing the lens curved array. As shown in FIG. 2A, the workpiece 20 of the present embodiment is made of transparent plastic, and has the same cross-section in a predetermined direction before processing the lens curved surface array. That is, the workpiece 20 of the present embodiment has a so-called cylindrical surface 27 (a surface having a curvature in one direction 28 but not having a curvature in a direction 29 orthogonal thereto) before processing the curved surface array for lenses. doing. A plurality of lens curved surface shapes 21 to be processed by the rotary tool 19 are defined on the cylindrical surface 27.

  FIG. 2B is an enlarged cross-sectional view of a portion indicated by reference sign K in FIG. 2A, which is a plane perpendicular to the direction 29 in which the cylindrical surface 27 does not have a curvature. Each curved surface shape 21 for a lens is defined by a reference position coordinate 23 and a relative position coordinate with respect to the reference position coordinate 23, and provides an optical axis 24. In the present embodiment, each lens curved surface shape 21 has a concave lens shape, and the reference position coordinates 23 of each lens curved surface shape 21 are the optical axis 24 of the lens curved surface shape 21 and the lens curved surface array. This coincides with the intersection with the cylindrical surface 27 before processing.

  Returning to FIG. 1, a tool spindle 18 is attached to the Y-axis arm 17, and a rotary tool 19 is attached to the tip of the tool spindle 18. In the present embodiment, in order to prevent interference with the workpiece 20, the rotation axis of the rotary tool 19 is inclined by a predetermined angle (for example, 45 °) with respect to the Y axis and the Z axis.

  Next, the processing method of the curved surface array for lenses of this Embodiment using the above processing machines is demonstrated.

  First, as shown in FIG. 1, the relative positional relationship between the tip (blade edge) of the rotary tool 19 and the B axis is grasped. For example, in a state where the dummy workpiece is held by the workpiece holder 16, the cylindrical workpiece is processed from the two directions of CW / CCW using the XZB axis, and the rotary tool 19 is processed based on the processing result. The relative position between the tip and the B axis is confirmed.

  Next, the workpiece 20 to be processed is held by the workpiece holder 16 on the B-axis rotary table 15 so that the direction 29 having no curvature of the cylindrical surface 27 is parallel to the B-axis.

  Then, information on each lens curved surface shape 21 (reference position coordinates 23 of each lens curved surface shape 21, relative position coordinates with respect to the reference position coordinates 23, angle of the optical axis 24, etc.) is designated for the numerical control device 31. Is done. These designations may be made manually by an operator via an input device (for example, a PC), but are usually made by reading a program (called a macro program) created in advance. FIG. 5 conceptually shows the relationship between the program and the machining program. An example of the machining program is shown in FIG.

  Next, as shown in FIG. 3, the X-axis table 12, the Y-axis arm 17, and the Z-axis table 14 are linearly moved based on the information of the designated first curved surface shape for lens 211, so that the rotation is performed. The tip of the tool 19 is moved to the reference position coordinate 231 of the first lens curved surface shape 211, and the B-axis rotation table 15 is rotated by the B-axis, so that the rotation axis of the rotary tool 19 is changed to the first lens curved surface. The optical axis 241 of the shape 211 is adjusted to form a predetermined relative angle (for example, 45 °). Thereafter, the B-axis rotation of the B-axis rotary table 15 is stopped until the processing of the first lens curved surface shape 211 is completed. Accordingly, the rotation axis of the rotary tool 19 is maintained at the predetermined relative angle with respect to the optical axis 241 of the first lens curved surface shape 211.

  Subsequently, based on the relative position coordinates of the first curved surface shape 211 for the lens, the tip of the rotary tool 19 is sequentially moved while the rotary axis of the rotary tool 19 is maintained parallel to its own axial direction. Thus, the first lens curved surface shape 211 is processed. A conventionally known subprogram is used for processing the first lens curved surface shape 211. Specifically, for example, as shown in FIG. 7, the moving track 25 of the rotary tool 19 is constituted by raster scanning in one direction and pick feed in a direction orthogonal thereto.

  Next, as shown in FIG. 4, the X-axis table 12, the Y-axis arm 17, and the Z-axis table 14 are linearly moved based on the information on the designated next curved surface shape 212 for lens, thereby rotating. The tip of the tool 19 is moved to the reference position coordinate 232 of the curved surface shape 212 for the lens to be processed next, and the B-axis rotary table 15 is rotated by the B-axis, so that the rotation axis of the rotary tool 19 is changed to the next axis. The optical axis 242 of the lens curved surface shape 212 is adjusted to make the predetermined relative angle. Thereafter, the B-axis rotation of the B-axis rotary table 15 is stopped until the processing of the next lens curved surface shape 212 is completed. Accordingly, the rotation axis of the rotary tool 19 is maintained at the predetermined relative angle with respect to the optical axis 242 of the next lens curved surface shape 212.

  Subsequently, based on the relative position coordinates of the curved surface shape 212 for the next lens, the tip of the rotary tool 19 is sequentially moved while the rotary axis of the rotary tool 19 is maintained parallel to the axial direction of itself. Thus, the next lens curved surface shape 212 is processed. A conventionally well-known subprogram is also used for processing the next lens curved surface shape 211. In the present embodiment, the macro program used for processing the next lens curved surface shape 212 need not be the same as the macro program used for processing the first lens curved surface shape 211.

  While the curved surface shapes 211 and 212 for each lens are processed, the rotation axis of the rotary tool 19 is maintained at a predetermined relative angle with respect to the optical axes 241 and 242 of the curved surface shapes 211 and 212 for the lenses. In the processing of the curved surface shapes 211 and 212 for each lens, variations in the movement trajectory 25 of the rotary tool 19, that is, the movement trajectory (machining trajectory) of the cutting edge are suppressed. Accordingly, it is possible to obtain a processing accuracy with less variation (uniform) between the first lens curved surface shape 211 and the next lens curved surface shape 212 to be processed.

  Thereafter, in the same manner, the remaining lens curved surface shape 21 in the curved workpiece 20 is sequentially processed, so that a lens curved surface array as shown in FIGS. 8A and 8B is processed. .

  Next, specific examples will be described.

  As the processing machine 10, a simultaneous 5-axis control type ultra-precision processing machine of ULC / ULG series manufactured by Toshiba Machine Co., Ltd. was used, and for the rotary tool 19, a single crystal diamond end mill (R = 0.3 mm) was used. The rotary tool 19 was mounted so that the rotational axis thereof coincided with the rotational axis of the tool spindle 18, and the rotational radius of the rotary tool 19 and the cutting edge radius of the rotary tool 19 were substantially matched. The rotation axis of the rotary tool 19 was inclined 45 ° with respect to the Y axis and the Z axis in order to prevent interference with the workpiece 20.

  And the curved surface array (lens array) for lenses was processed by the processing method of this Embodiment as mentioned above. According to the knowledge of the present inventors, the surface roughness is determined by the processing conditions (such as the feed speed of the processing tool). Generally, an optical surface is required to have a surface roughness of 10 nmRa or less for an inexpensive lens (about 300,000 pixels) and a surface roughness of 5 nmRa or less for a medium lens (about 4 million pixels).

  Here, the rotational speed of the rotary tool 19 was set to 22000 / min. In the processing of the curved surface shape 21 for each lens, the moving trajectory 25 of the rotary tool 19 has a pattern (raster scanning in the Y axis direction, raster scanning in the Y axis direction, X axis direction) from the viewpoint of processing time and uniformity of processing accuracy. The feed rate was 45 mm / min so that the surface roughness was 5 nmRa or less. Each curved surface shape 21 for lenses is a concave spherical surface with R = 0.8 mm, and the number of processed curved surface shapes 21 for lenses is 96 (12 × 8).

  Then, after processing, the shape accuracy and surface roughness of each curved surface shape 21 for lens were evaluated. Since it was difficult to properly evaluate the lens curved surface shape 21 located on the curved surface, the shape accuracy was evaluated at an arbitrary position. Further, in order to confirm the distortion of the shape, as shown in FIG. 8B, the shape evaluation in the cross direction was performed. From the evaluation results, values of a shape accuracy of 83 nm PV, an absolute value of surface roughness of 4 nm Ra, and a deviation of surface roughness of ± 1 nm Ra were obtained. These values were confirmed to be accurate enough to satisfy the requirements for optical surfaces.

  That is, the actual verification by the present inventors as described above confirmed that the lens array in which the absolute value of the surface roughness of each curved surface shape 21 for the lens is 5 nmRa or less is realized by the present embodiment. It was also confirmed that the lens array in which the deviation of the surface roughness of each lens curved surface shape 21 is ± 5 nmRa or less is realized by this embodiment. Further, when the lens array mold (usually a mold) or a mirror is processed by the processing method of the present embodiment, the same effect as when the lens array is processed is obtained.

  That is, according to the present embodiment as described above, the rotational axis of the rotary tool 19 is at a predetermined relative angle with respect to the optical axis of the curved surface shape 21 for lens while each curved surface shape 21 for lens is processed. Thus, variation in the movement trajectory of the rotary tool 19, that is, the movement trajectory (machining trajectory) 25 of the cutting edge, is suppressed in the processing of the curved surface shape 21 for each lens. Accordingly, it is possible to obtain a processing accuracy with less variation (uniform) between the plurality of lens curved surface shapes 21 to be processed.

  In the present embodiment, the first lens curved surface shape 211 and the next lens curved surface shape 212 do not have to be the same. Even if they are different, processing accuracy with little variation (uniform) can be obtained. Therefore, for example, by actively changing the curvature of the curved surface shape 21 for each lens in accordance with the distance from the light source, it is possible to improve the optical characteristics of the entire curved lens array.

  In this embodiment, as shown in FIGS. 3 and 4, the curved surface shapes 211 and 212 for concave lenses are processed on the curved workpiece 20, but as shown in FIGS. 9 and 10, The curved surface shapes 211 ′ and 212 ′ having a convex lens shape can be processed.

  Further, in the present embodiment, as shown in FIG. 7, the moving trajectory 25 of the rotary tool 19 is defined by raster scanning in one direction and pick feed in a direction orthogonal thereto, but is not limited to this pattern. For example, as shown by reference numeral 25 in FIG. 11, the rotary tool 19 may be moved away from the center of the lens curved surface shape 21. When processing a curved surface shape for a lens having a convex lens shape, the processing method is preferable because an initial cutting amount is small.

  Further, the workpiece 20 may be rotated about the A (C) axis on the B-axis rotary table 15. According to this, it is possible to process a plurality of curved surface shapes for lenses not only on the workpiece 20 having the same shape in cross section in a predetermined direction as shown in FIG. 2 but also on a workpiece having a three-dimensional curved surface.

DESCRIPTION OF SYMBOLS 10 Processing machine 11 Bed 12 X-axis table 13 Column 14 Z-axis table 15 B-axis rotary table 16 Work holder 17 Y-axis arm 18 Tool spindle 19 Rotating tool 20 Work 21 Lens curved surface shape 23 Reference position coordinate 24 Optical axis 25 Rotation Tool movement trajectories 211, 211 ′ First lens curved surface shape 212, 212 ′ Next lens curved surface shape 231 First lens curved surface shape reference position coordinates 232 Next lens curved surface shape reference position coordinates 241 First lens Optical axis 242 at the reference position coordinates of the curved surface shape for the optical axis 31 at the reference position coordinates of the curved surface shape for the next lens

Claims (13)

A method of processing a curved surface array for a lens, wherein a curved surface shape for a plurality of lenses is processed with a rotary tool on a curved workpiece,
Each lens curved surface shape is defined by reference position coordinates and relative position coordinates relative to the reference position coordinates, and provides an optical axis.
The processing method is:
(1) The tip of the rotary tool is moved to the reference position coordinates of the curved surface shape for the lens that is the first object to be processed, and the rotation axis of the rotary tool is at a predetermined relative angle with the optical axis of the first curved surface shape for the lens. Adjusting the process so that
(2) Based on the relative position coordinates of the first curved surface shape for the lens, the tip of the rotary tool is sequentially moved while the rotary axis of the rotary tool is maintained parallel to its own axial direction. Processing the first curved surface shape for the lens;
(3) The tip of the rotating tool is moved to the reference position coordinate of the curved surface shape for the lens to be processed next, and the rotation axis of the rotating tool is set to the predetermined relative angle with the optical axis of the curved surface shape for the next lens. The process of making adjustments,
(4) Based on the relative position coordinates of the curved surface shape for the next lens, the tip of the rotary tool is sequentially moved while maintaining the rotary axis of the rotary tool parallel to its own axial direction. The process of processing the curved surface shape for the next lens,
A method of processing a curved surface array for lenses, comprising: 2. The method of processing a curved surface array for a lens according to claim 1, wherein the first curved surface shape for a lens is different from the next curved surface shape for a lens. 3. The processing method for a curved surface array for a lens according to claim 1, wherein the workpiece has a same cross-section in a predetermined direction before processing the curved surface array for a lens. 4. The method for processing a curved surface array for a lens according to claim 1, wherein the rotary tool is a single crystal diamond end mill. A lens array processed by the processing method according to claim 1. 6. The lens array according to claim 5, wherein the absolute value of the surface roughness of each lens curved surface shape is 5 nmRa or less. The lens array according to claim 5 or 6, wherein a deviation of surface roughness of each lens curved surface shape is ± 5 nmRa or less. 5. A lens array mold processed by the processing method according to claim 1. 9. The mold for a lens array according to claim 8, wherein the absolute value of the surface roughness of each lens curved surface shape is 5 nmRa or less. The lens array molding die according to claim 8 or 9, wherein the deviation of the surface roughness of each lens curved surface shape is ± 5 nmRa or less. A mirror processed by the processing method according to claim 1. The mirror according to claim 11, wherein the absolute value of the surface roughness of each lens curved surface shape is 5 nmRa or less. The mirror according to claim 11 or 12, wherein a deviation in surface roughness of each lens curved surface shape is ± 5 nmRa or less.

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