WO2007116716A1 - Fresnel lens sheet - Google Patents

Fresnel lens sheet Download PDF

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Publication number
WO2007116716A1
WO2007116716A1 PCT/JP2007/056321 JP2007056321W WO2007116716A1 WO 2007116716 A1 WO2007116716 A1 WO 2007116716A1 JP 2007056321 W JP2007056321 W JP 2007056321W WO 2007116716 A1 WO2007116716 A1 WO 2007116716A1
Authority
WO
WIPO (PCT)
Prior art keywords
fresnel lens
mold
cutting
lens sheet
cutting speed
Prior art date
Application number
PCT/JP2007/056321
Other languages
French (fr)
Japanese (ja)
Inventor
Yoshihiro Kumagai
Takao Kibushi
Masato Aida
Takahiro Ogura
Tatsuya Ueda
Original Assignee
Kuraray Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kuraray Co., Ltd. filed Critical Kuraray Co., Ltd.
Priority to TW096110671A priority Critical patent/TW200745613A/en
Publication of WO2007116716A1 publication Critical patent/WO2007116716A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1847—Manufacturing methods
    • G02B5/1852—Manufacturing methods using mechanical means, e.g. ruling with diamond tool, moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B5/00—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor
    • B23B5/36—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor for turning specially-shaped surfaces by making use of relative movement of the tool and work produced by geometrical mechanisms, i.e. forming-lathes
    • B23B5/46—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor for turning specially-shaped surfaces by making use of relative movement of the tool and work produced by geometrical mechanisms, i.e. forming-lathes for turning helical or spiral surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1876—Diffractive Fresnel lenses; Zone plates; Kinoforms

Definitions

  • the present invention relates to a Fresnel lens sheet used for a rear projection screen or the like.
  • Rear projection televisions are widely used in which an optical image of a projector such as a CRT or a liquid crystal device is enlarged and projected onto a rear projection screen by a projection lens so that a large screen image can be obtained.
  • a rear projection screen used in a rear projection television generally includes a Fresnel lens sheet that directs image light from a projection lens toward an observer, and a field of view by diffusing light from the Fresnel lens sheet in a horizontal direction or a vertical direction. It consists of a single lens sheet that widens the corners.
  • a Fresnel lens sheet has a sawtooth prism array arranged concentrically on the sheet surface.
  • a so-called folded type Fresnel lens sheet is known in which the center of this concentric circle is arranged in the vicinity of the approximate center of the sheet and exhibits the effect of a convex lens by the refraction action of the prism row.
  • the refractive type Fresnel lens sheet if the arrangement pitch of the prism rows is the same, the height of the prism row is the lowest near the center of the concentric circle, and the height increases toward the outer periphery.
  • JP-A-61-269135 Patent Document 1
  • JP-A-61-277935 Patent Document 2
  • the center of the concentric circle is arranged outside the sheet, and the triangular prism array, rectangular
  • a so-called total reflection type Fresnel lens sheet using total reflection of a prism array is also known.
  • the height of the prism row in the total reflection type Fresnel lens sheet hardly changes depending on the radial direction.
  • a relatively soft metal plate such as copper, brass, stainless steel, or nickel is used as a mold master, and a lathe is used with a cutting tool.
  • a mold for forming a Fresnel lens having a concave-convex shape opposite to that of a Fresnel lens is manufactured, and the concave-convex shape is transferred to the surface of a light-transmitting material by a hot press manufacturing method, a transfer method using photocured grease, or the like. It is manufactured by doing.
  • a resin mold made by transferring the shape of the metal mold for molding the Fresnel lens, which is then used to mold the Fresnel lens sheet. Used as a mold.
  • FIG. 11 is an explanatory diagram of a method for manufacturing the Fresnel lens molding die 10 when the Fresnel lens molding die 10 is cut from the outer periphery of the Fresnel lens toward the center.
  • the cutting edge 21 of the cutting tool 20 is set in parallel to the mold surface 10a corresponding to the Fresnel surface, and the mold tool 11 is rotated to cut to a predetermined depth with the cutting tool 20.
  • the mold surface 10a corresponding to one pitch of the concentric Fresnel surface is formed, and thereafter, the mold surface 10a corresponding to the Fresnel surface on the sequential center side is formed in the same manner.
  • the mold surface 10b corresponding to the rise surface is formed by setting the other cutting edge 22 of the cutting tool 20 parallel to the mold surface 10b corresponding to the rise surface and cutting to a predetermined depth (patent) Literature 3, patent literature 4).
  • the cutting edge 21 of the cutting tool 20 is set in parallel to the mold surface 10a corresponding to the Fresnel surface, and the feed direction of the tip 23 of the cutting blade 20 is set to a metal corresponding to the rise surface.
  • Set parallel to the mold surface 10b and cut to a predetermined depth Patent Document 5).
  • Patent Document 1 JP-A-61-269135
  • Patent Document 2 Japanese Patent Laid-Open No. 61-277935
  • Patent Document 3 Japanese Patent Laid-Open No. 4-127101
  • Patent Document 4 Japanese Patent Laid-Open No. 9-236701
  • Patent Document 5 Japanese Patent Laid-Open No. 2002-239802
  • a surface 10 a corresponding to the Fresnel surface is cut with a cutting tool 20.
  • a nodule 12 may be generated at the top of the mold 10 for forming the Fresnel lens sheet.
  • the burr 12 is transferred as a recess on the Fresnel lens sheet, or transferred as a recess on the resin mold, which is transferred as a protrusion on the Fresnel lens sheet. It is visually recognized as a point-like defect portion or a streak-like defect portion, and deteriorates the appearance quality.
  • the generation of the nose 12 can be suppressed by lowering the cutting speed of the cutting tool 20 (mZ rotation). However, if the cutting speed is lowered, the roughness of the rise surface becomes insufficient and the cutting time of the mold becomes excessively long.
  • a lens pitch of about 0.05 to 0.1 mm used for a rear projection screen with a diagonal size force of 0 to 70 inches the height of the Fresnel lens is 0 to 0.05 mm at the center, and at the outer periphery.
  • a mold for Fresnel lens sheet with a thickness of 0.05 to 0.1 mm is cut under the conditions that the rotation speed of the mold master is about 1 rotation Z seconds and the cutting speed is several mZ rotation, Cutting requires a long time of several days to one week or more. Therefore, the cutting speed must be set from the viewpoint of cutting time which is not only to prevent the generation of burrs 12.
  • a specific top shape is unevenly distributed in a mold for molding a Fresnel lens, and in a Fresnel lens sheet molded using the mold, a specific top shape unevenness portion in the mold is formed.
  • the light scattering directions were aligned at the corresponding parts, and concentric streaks were observed.
  • the cutting bit is spirally cut up to one rotation of the mold master, and the depth of the cutting tool increases as shown in Fig. 14 (a).
  • the shape of the top part 13 of the mold 10 is as shown in FIGS. Different.
  • the cutting tool As shown in FIG. 15, in the obtained mold, the specific top shape is unevenly distributed in the radial direction because the positions where the metal starts to contact the mold are aligned in the specific radial direction.
  • the present invention provides a gold plate that does not excessively lengthen the cutting time in a Fresnel lens sheet having fine irregularities derived from the cutting traces of the mold on the rise surface.
  • the object is to eliminate the problem of unevenness of mold burrs and specific top shapes.
  • the present inventors (1) in order to solve the problem of mold sag, not all the depths to be cut. It is not necessary to keep the cutting speed by cutting tool mZ rotation) low, and it is particularly effective to keep the cutting speed low when cutting the bottom of the valley of the mold. (2) Uneven distribution of specific top shape In order to solve the problem, it is not necessary to lower the cutting speed over the entire depth of cutting, and it is effective to make the cutting speed at the top of the mold smaller than the cutting speed at the bottom of the die.
  • the switching portion of the cutting speed is a step in the inner peripheral area of the Fresnel lens sheet obtained from the mold. Therefore, (4) the cutting speed is constant in the inner peripheral area of the mold master so that there are no conspicuous steps on the small unevenness of the rise surface. It is preferable to control a plurality of cutting speeds from the viewpoint of uneven distribution of a specific top shape and cutting speed, and the Fresnel lens sheet obtained from the die mold formed in this way is at least in the outermost peripheral area.
  • the present invention has been completed by finding that it has minute irregularities with different pitches in one rise surface.
  • the present invention provides a Fresnel lens sheet in which minute irregularities along the ridge line of the Fresnel lens are formed at different pitches in one rise surface in at least the outermost peripheral region of the lens surface.
  • a method of manufacturing the Fresnel lens sheet there is a method of manufacturing a Fresnel lens molding die force obtained by cutting a mold master with a lathe using a cutting knife.
  • a method for producing a Fresnel lens sheet using a mold in which a mold surface corresponding to a rise surface of a Fresnel lens is cut at two cutting speeds at least in the outermost peripheral region.
  • the pitch of the minute irregularities in the portion corresponding to the valley bottom of the mold for molding the Fresnel lens is P1, and the minute irregularities in the portion corresponding to the top side from the pitch.
  • PK P2 When the pitch is set to P2, an embodiment of PK P2 is provided, and as a manufacturing method of the corresponding Fresnel lens sheet, the cutting speed of the bottom of the mold surface corresponding to the rise surface of the Fresnel lens is vl, If the top notch speed is v2, then a mode where vl ⁇ v2 is provided.
  • the pitch of the minute irregularities corresponding to the top of the mold for molding the Fresnel lens is P3, and the minute irregularities corresponding to the valley bottom side from that is P3.
  • P3 and P4 are provided, and the corresponding Fresnel lens sheet manufacturing method is v3, where the cutting speed at the top of the mold surface corresponding to the rise surface of the Fresnel lens is v3, If the incision speed at the bottom of the valley is v4, a mode of v3 to v4 is provided.
  • the mold for molding the Fresnel lens As the mold for molding the Fresnel lens, at least the outermost peripheral region of the mold master is cut at two cutting speeds.
  • the problem of burrs and uneven distribution of specific top shapes in the mold is solved by reducing the cutting speed, and the increase in the cutting time of the entire mold and the accompanying increase in the manufacturing cost of the mold are minimized. be able to.
  • the Fresnel lens sheet of the present invention obtained by this manufacturing method is free from defects due to mold burrs and the uneven distribution of a specific top shape, and the manufacturing cost is also suppressed.
  • the resulting Fresnel lens sheet of the present invention has a microscopic portion of the rise surface corresponding to the valley bottom of the Fresnel lens molding die.
  • FIG. 1 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
  • FIG. 2 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
  • FIG. 3 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
  • FIG. 4 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
  • FIG. 5 is an explanatory diagram of light rays in a total reflection type Fresnel lens sheet.
  • FIG. 6 is a cross-sectional view showing the relationship between the Fresnel angle and the cutting tool blade angle in the inner peripheral region.
  • FIG. 7 is a cross-sectional view showing the relationship between the Fresnel angle and the cutting tool blade angle in the outer peripheral region.
  • FIG. 8 is an explanatory diagram of an outermost peripheral region in a total reflection type Fresnel lens sheet.
  • FIG. 9 is an explanatory view of a cutting method of the die surface corresponding to the rise surface in the outer peripheral region. is there.
  • FIG. 10 is an explanatory diagram of light rays on the rise surface of the Fresnel lens sheet.
  • FIG. 11 is an explanatory diagram of a method for manufacturing a mold for molding a Fresnel lens.
  • FIG. 12 is an explanatory diagram of ghost light.
  • FIG. 13 is a cross-sectional view of a mold for molding a Fresnel lens with burrs.
  • FIG. 14 is an explanatory view of the top of a specific shape formed in a mold for molding a Fresnel lens.
  • FIG. 15 is an explanatory view showing the uneven distribution state of a specific top shape in a mold for molding a Fresnel lens.
  • the cutting speed refers to the depth of the tip 23 of the cutting bit 20 per one rotation of the die master when the die master is cut with a lathe using a cutting tool (die master Thickness
  • the Fresnel lens sheet includes both a refractive Fresnel lens sheet and a total reflection Fresnel lens sheet.
  • the rise surface of the total reflection type Fresnel lens sheet refers to the surface other than the light incident part and the reflection part.
  • the surface drawn on the uneven surface is the rise surface. lb.
  • the inner peripheral region is defined as 0 1 + when the blade angle of the cutting tool 20 for cutting the die 10 is ⁇ 1 (degrees) and the Fresnel angle 0 2 (degrees). 0 2 An area that is 90 degrees.
  • the outer peripheral region is a region where ⁇ 1 + ⁇ 2 ⁇ 90 degrees as shown in FIG. That is, in the Fresnel lens, the Fresnel angle increases from the center toward the outer periphery, so a certain point in the radial direction from the center becomes 0 1 + 0 2 90 degrees (inner peripheral region), and 0 on the outer peripheral side. 1 + ⁇ 2 ⁇ 90 degrees (outer peripheral area).
  • the total reflection type Fresnel lens sheet has a smaller change in the height of the prism row in the sheet surface and the ratio of the rise surface length to the height of the prism row than in the refraction type Fresnel lens sheet. Therefore, in the present invention, there is substantially no inner peripheral region. Therefore, when cutting the mold of the total reflection type Fresnel lens sheet, it is preferable to switch the cutting speed described later over the entire surface.
  • the outermost peripheral region means a range in which the central force is 10% closer to the outer periphery of the outermost periphery of the Fresnel lens formed concentrically and in the vicinity thereof.
  • the outermost peripheral area Means the range of about 10% of the outermost RO.
  • the mold surface 10b corresponding to the rise surface is formed by the cutting blade 21 opposite to the cutting surface 21 for cutting the mold surface 10a corresponding to the Fresnel surface of the Fresnel lens sheet. Will be cut.
  • the cutting tool 20 is simply continuously cut, the rise surface becomes a mirror surface. Therefore, as shown in FIG. 9, the cutting knot 20 is cut obliquely. In this case, if the oblique angle is too large, as shown in FIG. 10, in the Fresnel lens sheet 1 obtained from this mold, when light is incident on the lens surface, light is also applied to the light lb unnecessarily.
  • the angle (rise angle ⁇ 3) for cutting obliquely cannot be increased. Therefore, in the outer peripheral region, the angle at which the cutting bit 20 is cut obliquely is smaller than in the inner peripheral region, and the unevenness formed on the rise surface is reduced. Gatsutsu In the outer peripheral region, even if there is a step difference in the uneven pitch of the rise surface due to switching of the cutting speed of the mold, the step is not noticeable. Therefore, in the present invention, in the outer peripheral region, it is preferable to switch the cutting speed in terms of both a problem based on uneven burrs of the mold and the specific shape of the top and a problem of the cutting speed. On the other hand, it is preferable not to switch the cutting speed that causes a conspicuous step on the rise surface. Especially in the inner peripheral area, it is preferable not to switch the cutting speed greatly.
  • the mold master depending on the form of use of the mold, when used as it is for press molding, a hard metal plate is used, and the resin mold is molded from resin.
  • the resin mold is molded from resin.
  • metal plates that are easy to cut. Considering durability, it is usually selected appropriately from a metal plate such as copper, brass, stainless steel, or nickel.
  • FIG. 1 is a cross-sectional explanatory view of one embodiment of a Fresnel lens molding die 10A used for manufacturing the Fresnel lens sheet of the present invention.
  • this Fresnel lens molding die 10A has a cutting tool 20 with a cutting tool 20 when the mold master is cut on a lathe.
  • minute irregularities substantially parallel to the ridge line of the mold are formed in a streak shape.
  • the area A2 including the outer peripheral area is cut at two cutting speeds vl ⁇ mZ rotation and ⁇ 2 ⁇ / rotation (provided that vl ⁇ v2).
  • a feature is that minute irregularities are formed in the mold surface 10b corresponding to the rise surface at two pitches of P1 ⁇ m and P2 / zm! /
  • the cutting speed in the feed direction of the tip 23 of the cutting bit 20 is constant at vl ⁇ mZ rotation, and the outer peripheral area In the region A2 including, the cutting speed is vl ⁇ mZ rotation at the valley bottom B1 and ⁇ 2 ⁇ mZ rotation (where vl ⁇ v2) in the range B2 on the top side.
  • the central area In Al the pitch of the minute irregularities on the mold surface 10b corresponding to the rise surface is a single PI ⁇ m, and in the area A2 including the outer peripheral region, the minute irregularities in the mold surface 10b corresponding to one rise surface.
  • pitch P1 ⁇ m at valley bottom B1 and pitch P2 ⁇ m (however, PI ⁇ P2) in range B2 on the top side.
  • the valley bottom B1 has a dwell cut lj (a step does not occur in the individual concentric Fresnel planes.
  • rotate the mold master one or more times with a constant depth of cut to polish the Fresnel surface), that is, reduce the cutting speed immediately before the deepest part of the mold.
  • the area A2 including the outer peripheral area by providing an area with a high cutting speed in the area B2 on the top side, the roughness of the fine irregularities on the rise surface is increased. It is possible to increase the diffusibility of the rise surface and shorten the cutting time.
  • the specific preferable values of the cutting speeds vl and v2 depend on the material of the mold, the cutting edge angle of the cutting bit 20, the roughness of the rise surface required and the cutting time, etc.
  • vl is a force S of 0.5 to 2.5 / zm / rotation S, preferably 1.0 to 2 rotations. It is particularly preferable that v2 is 2.5 to 10 ⁇ mZ rotation, particularly 2.5 to 6 ⁇ m / rotation.
  • the depth direction range of the valley bottom B1 to be cut at this cutting speed v2 is preferably 5 to 50 ⁇ m, more preferably 10 ⁇ m or more, and the cutting time is preferably shortened.
  • the range in which the cutting speed is vl may be changed depending on the position in the radial direction.
  • FIG. 2 is a cross-sectional explanatory view of a different mode of the Fresnel lens molding die used for manufacturing the Fresnel lens sheet of the present invention.
  • This mold 10B for forming a Fresnel lens has an area A3 on the center side of the inner peripheral area.
  • the cutting speed in the feed direction of the tip 23 of the cutting bit 20 is constant at ⁇ 3 / ⁇ ⁇ rotation and includes the outer peripheral area. Even in ⁇ 4, the cutting speed of the top region ⁇ 3 is constant at v3 mZ rotation, and the cutting speed in the range B4 from the top to the valley bottom is set.
  • v3 is preferably 0.5 to 2.5 / zm / rotation, and more preferably 1.0 to 2.
  • ⁇ 4 is preferably 2.5 to 10 ⁇ m rotation, particularly 3.0 to 6 ⁇ m / rotation.
  • the depth range of the top part B3 where this cutting speed v3 is provided is not as good as that even if it is provided in a wider range where about 3 pitches are preferred.
  • the range in which the cutting speed is v3 may be changed depending on the position in the radial direction.
  • the Fresnel lens molding die 10C in FIG. 3 has a constant cutting speed of vl ⁇ mZ in the area A1 that coincides with the inner peripheral area, and the cutting speed in the area A2 that coincides with the outer peripheral area.
  • the cutting speed is ⁇ 2 ⁇ m Z rotation (however, vl ⁇ v2, PI ⁇ P2).
  • the cutting speed is constant in the v1 ⁇ mZ rotation in the area A1 that coincides with the inner peripheral area, and the cutting speed is set in the valley bottom B1 in the area A2 that coincides with the outer peripheral area.
  • Vl ⁇ rotation, and the top region ⁇ 3 is ⁇ 3 ⁇ mZ rotation, and the cutting speed v2 between the valley bottom B1 and the top region B3 is larger than vl and v3.
  • the Fresnel lens sheet of the present invention can be used in rear projection televisions, overhead projectors, knocklight lens sheets, reflective screens, and the like.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Overhead Projectors And Projection Screens (AREA)

Abstract

Problems such as burr of the die and uneven distribution of a specific top shape of a Fresnel lens sheet having micro protrusions and recesses derived from cut trace of a die on the rise face are eliminated without prolonging the cutting time excessively. At least in the outermost circumferential region of the lens face of a Fresnel lens sheet (1), micro protrusions and recesses are formed on one rise face (1b) at different pitches along the ridgeline of the Fresnel lens. Assuming the pitch of micro protrusions and recesses at a portion corresponding to a root portion (B1) of a Fresnel lens molding die (10a) is P1, and the pitch of micro protrusions and recesses at a portion (B2) corresponding to the upper side from the root portion is P2, a relation of P1<P2 is preferably satisfied with regard to the rise face.

Description

明 細 書  Specification
フレネノレレンズシート 技術分野  Fresno lens sheet technology
[0001] 本発明は、背面投射型スクリーン等に用いられるフレネルレンズシートに関する。  The present invention relates to a Fresnel lens sheet used for a rear projection screen or the like.
背景技術  Background art
[0002] CRTや液晶デバイス等のプロジェクタ一力ゝらの光学像を投射レンズで背面投射型 スクリーンに拡大投射し、大画面の映像を得られるようにする背面投射型テレビが普 及している。背面投射型テレビで用いられる背面投射型スクリーンは、一般に、投射 レンズからの映像光を観察者の方向に向けるフレネルレンズシートと、フレネルレンズ シートからの光を水平方向又は垂直方向に拡散させて視野角を広げるレンチキユラ 一レンズシートから構成されて 、る。  [0002] Rear projection televisions are widely used in which an optical image of a projector such as a CRT or a liquid crystal device is enlarged and projected onto a rear projection screen by a projection lens so that a large screen image can be obtained. . A rear projection screen used in a rear projection television generally includes a Fresnel lens sheet that directs image light from a projection lens toward an observer, and a field of view by diffusing light from the Fresnel lens sheet in a horizontal direction or a vertical direction. It consists of a single lens sheet that widens the corners.
[0003] フレネルレンズシートは、鋸波状のプリズム列がシート表面に同心円状に配列され たものである。フレネルレンズシートとしては、この同心円の中心が、シートの略中心 付近に配置され、プリズム列の屈折作用により凸レンズの効果を発揮する、所謂、屈 折型フレネルレンズシートが知られている。屈折型フレネルレンズシートでは、プリズ ム列の配列ピッチが同一であればプリズム列の高さは同心円の中心付近が最も低く 、外周部ほど高くなる。この他、特開昭 61— 269135号 (特許文献 1)、特開昭 61— 2 77935号 (特許文献 2)等のように、同心円の中心がシートの外に配置され、三角形 プリズム列、四角形プリズム列の全反射を利用した、所謂、全反射型フレネルレンズ シートも知られている。前述の屈折型フレネルレンズシートと異なり、全反射型フレネ ルレンズシートではプリズム列の高さは半径方向によってほとんど変わらない。  [0003] A Fresnel lens sheet has a sawtooth prism array arranged concentrically on the sheet surface. As the Fresnel lens sheet, a so-called folded type Fresnel lens sheet is known in which the center of this concentric circle is arranged in the vicinity of the approximate center of the sheet and exhibits the effect of a convex lens by the refraction action of the prism row. In the refractive type Fresnel lens sheet, if the arrangement pitch of the prism rows is the same, the height of the prism row is the lowest near the center of the concentric circle, and the height increases toward the outer periphery. In addition, as shown in JP-A-61-269135 (Patent Document 1), JP-A-61-277935 (Patent Document 2), etc., the center of the concentric circle is arranged outside the sheet, and the triangular prism array, rectangular A so-called total reflection type Fresnel lens sheet using total reflection of a prism array is also known. Unlike the above-described refractive Fresnel lens sheet, the height of the prism row in the total reflection type Fresnel lens sheet hardly changes depending on the radial direction.
[0004] フレネルレンズシートの製造方法につ!、ては、一般に、銅、真鍮、ステンレス、 -ッ ケル等の比較的軟質の金属板を金型原盤とし、それを旋盤で切削バイトを用いて切 削することにより、フレネルレンズの逆の凹凸形状を有するフレネルレンズ成形用金 型を製造し、その凹凸形状を熱プレス製法、光硬化榭脂による転写法等によって光 透過性材料の表面に転写することにより製造される。また、フレネルレンズ成形用金 属型の形状を転写した榭脂製の成形型を製造し、これをフレネルレンズシートの成形 型として用 、ることちある。 [0004] A method of manufacturing a Fresnel lens sheet! In general, a relatively soft metal plate such as copper, brass, stainless steel, or nickel is used as a mold master, and a lathe is used with a cutting tool. By cutting, a mold for forming a Fresnel lens having a concave-convex shape opposite to that of a Fresnel lens is manufactured, and the concave-convex shape is transferred to the surface of a light-transmitting material by a hot press manufacturing method, a transfer method using photocured grease, or the like. It is manufactured by doing. We also manufactured a resin mold made by transferring the shape of the metal mold for molding the Fresnel lens, which is then used to mold the Fresnel lens sheet. Used as a mold.
[0005] 図 11は、フレネルレンズ成形用金型 10をフレネルレンズの外周から中心方向へ切 削する場合のフレネルレンズ成形用金型 10の製造方法の説明図である。同図に示 すように、切削バイト 20の切刃 21を、フレネル面に対応する金型面 10aに平行に設 定し、金型原盤 11を回転しつつ切削バイト 20で所定の深さまで削ることにより、同心 円状のフレネル面の 1ピッチ分に対応する金型面 10aを形成し、以降同様にして、順 次中心側のフレネル面に対応する金型面 10aを形成していく。また、ライズ面に対応 する金型面 10bは、切削バイト 20のもう一方の切刃 22をライズ面に対応する金型面 10bに平行に設定し、所定の深さまで削ることにより形成する（特許文献 3、特許文献 4)。また、他の切削方法としては、切削バイト 20の切刃 21をフレネル面に対応する 金型面 10aに平行に設定すると共に、切削ノイト 20の先端部 23の送り方向をライズ 面に対応する金型面 10bに平行に設定し、所定の深さまで切削する（特許文献 5)。  FIG. 11 is an explanatory diagram of a method for manufacturing the Fresnel lens molding die 10 when the Fresnel lens molding die 10 is cut from the outer periphery of the Fresnel lens toward the center. As shown in the figure, the cutting edge 21 of the cutting tool 20 is set in parallel to the mold surface 10a corresponding to the Fresnel surface, and the mold tool 11 is rotated to cut to a predetermined depth with the cutting tool 20. Thus, the mold surface 10a corresponding to one pitch of the concentric Fresnel surface is formed, and thereafter, the mold surface 10a corresponding to the Fresnel surface on the sequential center side is formed in the same manner. The mold surface 10b corresponding to the rise surface is formed by setting the other cutting edge 22 of the cutting tool 20 parallel to the mold surface 10b corresponding to the rise surface and cutting to a predetermined depth (patent) Literature 3, patent literature 4). As another cutting method, the cutting edge 21 of the cutting tool 20 is set in parallel to the mold surface 10a corresponding to the Fresnel surface, and the feed direction of the tip 23 of the cutting blade 20 is set to a metal corresponding to the rise surface. Set parallel to the mold surface 10b and cut to a predetermined depth (Patent Document 5).
[0006] ところで、図 12〖こ示すよう〖こ、フレネルレンズシート 1では、入射光 L0の入射角によ つてはフレネル面 laや入射面で意図しない反射が起こり、ライズ面 lbから出射する ゴースト光 L1が生じる。そこで、このようなゴースト光 L1を低減させるため、ライズ面 lb を粗ィ匕して拡散面にすることがなされており、この粗ィ匕のため、フレネルレンズ成形用 金型の製造時に、ライズ面 lbに対応する金型面に、所定の粗さの切削痕を形成する ことが提案されている (特許文献 3、特許文献 5)。  [0006] By the way, as shown in FIG. 12, in the Fresnel lens sheet 1, unintended reflection occurs on the Fresnel surface la or the incident surface depending on the incident angle of the incident light L0, and the ghost emitted from the rise surface lb. Light L1 is generated. Therefore, in order to reduce such ghost light L1, the rise surface lb is roughened to make a diffused surface. It has been proposed to form a cutting mark having a predetermined roughness on the mold surface corresponding to the surface lb (Patent Document 3 and Patent Document 5).
特許文献 1：特開昭 61— 269135号  Patent Document 1: JP-A-61-269135
特許文献 2：特開昭 61— 277935号  Patent Document 2: Japanese Patent Laid-Open No. 61-277935
特許文献 3 :特開平 4— 127101号公報  Patent Document 3: Japanese Patent Laid-Open No. 4-127101
特許文献 4 :特開平 9— 236701号公報  Patent Document 4: Japanese Patent Laid-Open No. 9-236701
特許文献 5：特開 2002 - 239802号公報  Patent Document 5: Japanese Patent Laid-Open No. 2002-239802
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0007] し力しながら、従来の方法で金型を切削し、フレネルレンズシートを製造すると、次 のような問題が生じていた。 [0007] However, when a Fresnel lens sheet is manufactured by cutting a mold by a conventional method while pressing, the following problems have occurred.
[0008] 第 1に、図 13に示したように、切削バイト 20でフレネル面に対応する面 10aを切削 した場合に、フレネルレンズシート成形用金型 10の頂部にノ リ 12が発生することがあ つた。バリ 12は、フレネルレンズシートに凹部として転写され、あるいは榭脂製成形型 に凹部として転写され、それがフレネルレンズシートに凸部として転写され、いずれに しても映像光が散乱して白い輝点状の欠陥部あるいは筋状の欠陥部として視認され 、外観品位を低下させる。 First, as shown in FIG. 13, a surface 10 a corresponding to the Fresnel surface is cut with a cutting tool 20. In this case, a nodule 12 may be generated at the top of the mold 10 for forming the Fresnel lens sheet. The burr 12 is transferred as a recess on the Fresnel lens sheet, or transferred as a recess on the resin mold, which is transferred as a protrusion on the Fresnel lens sheet. It is visually recognized as a point-like defect portion or a streak-like defect portion, and deteriorates the appearance quality.
[0009] 一般に、ノ リ 12の発生は、切削バイト 20の切り込み速度 mZ回転)を低くすれ ば抑えられる。しカゝしながら、切り込み速度を低くすると、ライズ面の粗ィ匕が不十分に なると共に、金型の切削時間が過度に長くなるという問題が生じる。  [0009] In general, the generation of the nose 12 can be suppressed by lowering the cutting speed of the cutting tool 20 (mZ rotation). However, if the cutting speed is lowered, the roughness of the rise surface becomes insufficient and the cutting time of the mold becomes excessively long.
[0010] 例えば、対角サイズ力 0〜70インチの背面投射型スクリーンに使用する、レンズピ ツチ 0. 05〜0. 1mm程度、フレネルレンズの高さが中央で 0〜0. 05mm,外周部で 0. 05〜0. 1mm程度のフレネルレンズシートの成形用金型を、金型原盤の回転速 度が 1回転 Z秒程度、切り込み速度が数 mZ回転、という条件で切削すると、この 金型の切削に数日〜 1週間以上という長時間が必要となる。従って、切り込み速度は 、バリ 12の発生防止だけでなぐ切削時間の観点からも設定しなければならない。  [0010] For example, a lens pitch of about 0.05 to 0.1 mm used for a rear projection screen with a diagonal size force of 0 to 70 inches, the height of the Fresnel lens is 0 to 0.05 mm at the center, and at the outer periphery. If a mold for Fresnel lens sheet with a thickness of 0.05 to 0.1 mm is cut under the conditions that the rotation speed of the mold master is about 1 rotation Z seconds and the cutting speed is several mZ rotation, Cutting requires a long time of several days to one week or more. Therefore, the cutting speed must be set from the viewpoint of cutting time which is not only to prevent the generation of burrs 12.
[0011] 第 2に、フレネルレンズ成形用金型に特定の頂部形状が偏在して形成され、その金 型を用いて成形したフレネルレンズシートでは、金型における特定の頂部形状の偏 在部位に対応する部分で光の散乱方向が揃い、同心円状の筋模様が観察されると いう問題があった。即ち、同心円状のフレネルレンズの 1ピッチ分を形成するにあたり 、金型原盤の 1回転分までは切削バイトは螺旋状に切り込み深さを増していくから、 図 14 (a)のフレネルレンズ成型用金型 10において、位置 Lと、そこから 180° 金型旋 盤を回転させて切り進んだ位置 Rとでは、金型 10の頂部 13の形状が同図（b)、 (c) に示すように異なる。一定の旋盤の回転速度、切り込み速度、ピッチ方向の移動速 度で切削を進めていく際に、 1ピッチ当たりの切削時間と 1周の回転時間とが略整数 倍の関係であると、切削バイトが金型に接触し始める位置が特定の半径方向に揃う ため、得られる金型では図 15に示すように、特定の頂部形状が半径方向に偏在する ことになる。  [0011] Second, a specific top shape is unevenly distributed in a mold for molding a Fresnel lens, and in a Fresnel lens sheet molded using the mold, a specific top shape unevenness portion in the mold is formed. There was a problem that the light scattering directions were aligned at the corresponding parts, and concentric streaks were observed. In other words, when forming one pitch of a concentric Fresnel lens, the cutting bit is spirally cut up to one rotation of the mold master, and the depth of the cutting tool increases as shown in Fig. 14 (a). In the mold 10, the shape of the top part 13 of the mold 10 is as shown in FIGS. Different. When cutting at a constant lathe rotational speed, cutting speed, and moving speed in the pitch direction, if the cutting time per pitch and the rotational time per revolution are approximately an integer multiple, the cutting tool As shown in FIG. 15, in the obtained mold, the specific top shape is unevenly distributed in the radial direction because the positions where the metal starts to contact the mold are aligned in the specific radial direction.
[0012] これに対しては、特定の頂部形状が、偏在することなぐランダムに存在するように 切削することも考えられるが、特定の頂部形状の形成を解消するものではなぐ根本 的な対策とはならない。 [0012] For this, it is conceivable to cut so that a specific top shape exists randomly without being unevenly distributed. However, the fundamental shape does not eliminate the formation of a specific top shape. It is not an effective measure.
[0013] 以上のような従来の問題点に対し、本発明は、ライズ面に、金型の切削痕に由来す る微小凹凸を有するフレネルレンズシートにおいて、切削時間を過度に長くすること なぐ金型のバリや特定の頂部形状の偏在の問題を解消することを目的とする。 課題を解決するための手段  [0013] In contrast to the conventional problems as described above, the present invention provides a gold plate that does not excessively lengthen the cutting time in a Fresnel lens sheet having fine irregularities derived from the cutting traces of the mold on the rise surface. The object is to eliminate the problem of unevenness of mold burrs and specific top shapes. Means for solving the problem
[0014] 本発明者らは、ライズ面に、金型の切削痕に由来する微小凹凸を有するフレネルレ ンズシートにおいて、（1)金型のノ リの問題を解消するには、必ずしも切り込む全ての 深さにわたって切削バイトによる切り込み速度 mZ回転)を低く抑える必要はなく 、金型の谷底部を切削するときに切り込み速度を低く抑えるのが特に有効であること 、（2)特定の頂部形状の偏在の問題を解消するためには、切り込む全ての深さにわた つて切り込み速度を低くする必要はなぐ金型の頂部の切り込み速度を、それより谷 底側の切り込み速度に比して小さくすることが有効であること、（3)ライズ面に対応する 金型面の切り込み速度を変えると、その切り込み速度の切り替え部分が、金型から得 られるフレネルレンズシートの内周領域では、段差として目立ちやすいこと、したがつ て、（4)ライズ面の微小凹凸に段差として目立つ部分が生じないように、金型原盤の内 周領域では切り込み速度を一定とし、反対に外周領域では、バリや特定の頂部形状 の偏在や切削速度の点から、複数の切り込み速度を制御するのが好ましいこと、こう して形成される金型カゝら得られるフレネルレンズシートは、少なくとも最外周領域にお いて、一つのライズ面内に、ピッチの異なる微小凹凸を有するものとなることを見出し 、本発明を完成させた。 [0014] In the Fresnel lens sheet having fine irregularities derived from the cutting traces of the mold on the rise surface, the present inventors (1) in order to solve the problem of mold sag, not all the depths to be cut. It is not necessary to keep the cutting speed by cutting tool mZ rotation) low, and it is particularly effective to keep the cutting speed low when cutting the bottom of the valley of the mold. (2) Uneven distribution of specific top shape In order to solve the problem, it is not necessary to lower the cutting speed over the entire depth of cutting, and it is effective to make the cutting speed at the top of the mold smaller than the cutting speed at the bottom of the die. (3) When the cutting speed of the mold surface corresponding to the rise surface is changed, the switching portion of the cutting speed is a step in the inner peripheral area of the Fresnel lens sheet obtained from the mold. Therefore, (4) the cutting speed is constant in the inner peripheral area of the mold master so that there are no conspicuous steps on the small unevenness of the rise surface. It is preferable to control a plurality of cutting speeds from the viewpoint of uneven distribution of a specific top shape and cutting speed, and the Fresnel lens sheet obtained from the die mold formed in this way is at least in the outermost peripheral area. The present invention has been completed by finding that it has minute irregularities with different pitches in one rise surface.
[0015] 即ち、本発明は、レンズ面の少なくとも最外周領域において、一つのライズ面内に、 フレネルレンズの稜線に沿った微小凹凸が異なるピッチで形成されているフレネルレ ンズシートを提供する。  That is, the present invention provides a Fresnel lens sheet in which minute irregularities along the ridge line of the Fresnel lens are formed at different pitches in one rise surface in at least the outermost peripheral region of the lens surface.
[0016] また、このフレネルレンズシートの製造方法として、金型原盤を旋盤で切削ノイトを 用いて切削したフレネルレンズ成形用金型力 フレネルレンズシートを製造する方法 であって、フレネルレンズ成形用金型として、少なくとも最外周領域において、フレネ ルレンズのライズ面に対応する金型面が 2通りの切り込み速度で切削されているもの を使用するフレネルレンズシートの製造方法を提供する。 [0017] 特に、レンズ面の少なくとも最外周領域のライズ面について、フレネルレンズ成形用 金型の谷底部に対応する部分の微小凹凸のピッチを P1、それより頂部側に対応する 部分の微小凹凸のピッチを P2とした場合に、 PK P2である態様を提供し、これに対 応するフレネルレンズシートの製造方法として、フレネルレンズのライズ面に対応する 金型面の谷底部の切り込み速度を vl、それより頂部側の切り込み速度を v2とした場 合に、 vl <v2とする態様を提供する。 [0016] Further, as a method of manufacturing the Fresnel lens sheet, there is a method of manufacturing a Fresnel lens molding die force obtained by cutting a mold master with a lathe using a cutting knife. Provided is a method for producing a Fresnel lens sheet using a mold in which a mold surface corresponding to a rise surface of a Fresnel lens is cut at two cutting speeds at least in the outermost peripheral region. [0017] In particular, with respect to the rise surface in at least the outermost peripheral region of the lens surface, the pitch of the minute irregularities in the portion corresponding to the valley bottom of the mold for molding the Fresnel lens is P1, and the minute irregularities in the portion corresponding to the top side from the pitch. When the pitch is set to P2, an embodiment of PK P2 is provided, and as a manufacturing method of the corresponding Fresnel lens sheet, the cutting speed of the bottom of the mold surface corresponding to the rise surface of the Fresnel lens is vl, If the top notch speed is v2, then a mode where vl <v2 is provided.
[0018] また、レンズ面の少なくとも最外周領域のライズ面について、フレネルレンズ成形用 金型の頂部に対応する部分の微小凹凸のピッチを P3、それより谷底部側に対応する 部分の微小凹凸のピッチを P4とした場合に、 P3く P4である態様を提供し、これに対 応するフレネルレンズシートの製造方法として、フレネルレンズのライズ面に対応する 金型面の頂部の切り込み速度を v3、それより谷底部側の切り込み速度を v4とした場 合に、 v3く v4とする態様を提供する。  [0018] Further, with respect to the rise surface in at least the outermost peripheral region of the lens surface, the pitch of the minute irregularities corresponding to the top of the mold for molding the Fresnel lens is P3, and the minute irregularities corresponding to the valley bottom side from that is P3. When the pitch is P4, P3 and P4 are provided, and the corresponding Fresnel lens sheet manufacturing method is v3, where the cutting speed at the top of the mold surface corresponding to the rise surface of the Fresnel lens is v3, If the incision speed at the bottom of the valley is v4, a mode of v3 to v4 is provided.
発明の効果  The invention's effect
[0019] 本発明のフレネルレンズシートの製造方法によれば、フレネルレンズ成形用金型と して、少なくとも金型原盤の最外周領域を 2通りの切り込み速度で切削したものを使 用するので、金型におけるバリの問題や特定の頂部形状の偏在の問題を、切り込み 速度の低下により解消し、かつ金型全体の切削時間の増加とそれに伴う金型の製造 コストの増加を最小限に抑制することができる。  [0019] According to the method for producing a Fresnel lens sheet of the present invention, as the mold for molding the Fresnel lens, at least the outermost peripheral region of the mold master is cut at two cutting speeds. The problem of burrs and uneven distribution of specific top shapes in the mold is solved by reducing the cutting speed, and the increase in the cutting time of the entire mold and the accompanying increase in the manufacturing cost of the mold are minimized. be able to.
[0020] したがって、この製造方法により得られる本発明のフレネルレンズシートは、金型の バリや特定の頂部形状の偏在に由来する欠陥が解消し、製造コストも抑制されたもの となる。  [0020] Therefore, the Fresnel lens sheet of the present invention obtained by this manufacturing method is free from defects due to mold burrs and the uneven distribution of a specific top shape, and the manufacturing cost is also suppressed.
[0021] 特に、レンズ面の少なくとも最外周領域において、谷底部の切り込み速度を vl ( μ mZ回転）、それより頂部側の切り込み速度を v2 ( μ mZ回転）とした場合に、 vl <v2 としてフレネルレンズ成形用金型を製造し、この金型からフレネルレンズシートを製造 すると、得られる本発明のフレネルレンズシートは、ライズ面について、フレネルレン ズ成形用金型の谷底部に対応する部分の微小凹凸のピッチを P1 m)、それより頂 部側に対応する部分の微小凹凸のピッチを P2 ( μ m)とした場合に、 P1 < P2となり、 ノ リによる欠陥が効果的に解消されたものとなる。 [0022] また、レンズ面の少なくとも最外周領域において、頂部の切り込み速度を v3 ( μ m/ 回転）、それより谷底部側の切り込み速度を v4 mZ回転）とした場合に、 v3<v4と してフレネルレンズ成形用金型を製造し、この金型からフレネルレンズシートを製造 すると、得られる本発明のフレネルレンズシートは、ライズ面について、フレネルレン ズ成形用金型の頂部に対応する部分の微小凹凸のピッチを P3 m)、それより谷底 部側に対応する部分の微小凹凸のピッチを P4 m)とした場合に、 P3く P4となり、 金型の特定の頂部形状の偏在に由来する同心円状のスジ模様の発生が抑制された ものとなる。 [0021] In particular, at least in the outermost peripheral region of the lens surface, when the cutting speed at the bottom of the valley is vl (μmZ rotation) and the cutting speed on the top side is v2 (μmZ rotation), vl <v2 When a Fresnel lens molding die is manufactured and a Fresnel lens sheet is manufactured from this mold, the resulting Fresnel lens sheet of the present invention has a microscopic portion of the rise surface corresponding to the valley bottom of the Fresnel lens molding die. When the pitch of the unevenness is P1 m), and the pitch of the minute unevenness in the part corresponding to the top side is P2 (μm), P1 <P2, and the defect due to the node is effectively eliminated It becomes. [0022] Also, at least in the outermost peripheral region of the lens surface, when the top cutting speed is v3 (μm / rotation) and the trough bottom cutting speed is v4mZ rotation), v3 <v4. When the Fresnel lens molding die is manufactured, and the Fresnel lens sheet is manufactured from this mold, the resulting Fresnel lens sheet of the present invention has a rise surface with a minute portion corresponding to the top of the Fresnel lens molding die. If the pitch of the unevenness is P3 m), and the pitch of the minute unevenness at the part corresponding to the valley bottom side is P4 m), it becomes P3 and P4, and it is a concentric circle derived from the uneven distribution of the specific top shape of the mold The generation of streak patterns is suppressed.
[0023] さらに、フレネルレンズ成形用金型の内周領域の切り込み速度を一定としてフレネ ルレンズ成形用金型を製造し、この金型カゝらフレネルレンズシートを製造すると、得ら れる本発明のフレネルレンズシートは、レンズ面の内周領域ではライズ面の微小凹凸 が単一のピッチで形成されたものとなり、ライズ面の微小凹凸が段差として目立つと いう問題を解消することができる。また、このフレネルレンズ成型用金型の製造時に、 外周領域では切り込み速度を切り替えて切削速度を向上させると、金型の製造コスト が抑制され、これにより得られるフレネルレンズシートも製造コストが抑制されたものと なる。  [0023] Further, when a Fresnel lens molding die is manufactured with the cutting speed of the inner peripheral region of the Fresnel lens molding die being constant, and a Fresnel lens sheet is manufactured from this mold cover, the resulting invention is obtained. In the Fresnel lens sheet, in the inner peripheral region of the lens surface, the minute unevenness of the rise surface is formed at a single pitch, and the problem that the minute unevenness of the rise surface is noticeable as a step can be solved. In addition, when manufacturing the mold for molding the Fresnel lens, if the cutting speed is changed in the outer peripheral region to improve the cutting speed, the manufacturing cost of the mold is suppressed, and the resulting Fresnel lens sheet is also suppressed in manufacturing cost. It becomes a thing.
図面の簡単な説明  Brief Description of Drawings
[0024] [図 1]図 1はフレネルレンズ成型用金型の断面の説明図である。 FIG. 1 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
[図 2]図 2はフレネルレンズ成型用金型の断面の説明図である。  FIG. 2 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
[図 3]図 3はフレネルレンズ成型用金型の断面の説明図である。  FIG. 3 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
[図 4]図 4はフレネルレンズ成型用金型の断面の説明図である。  FIG. 4 is an explanatory view of a cross section of a mold for molding a Fresnel lens.
[図 5]図 5は全反射型フレネルレンズシートにおける光線の説明図である。  FIG. 5 is an explanatory diagram of light rays in a total reflection type Fresnel lens sheet.
[図 6]図 6は内周領域における、フレネル角と切削バイトの刃角との関係を示す断面 図である。  FIG. 6 is a cross-sectional view showing the relationship between the Fresnel angle and the cutting tool blade angle in the inner peripheral region.
[図 7]図 7は外周領域における、フレネル角と切削バイトの刃角との関係を示す断面 図である。  FIG. 7 is a cross-sectional view showing the relationship between the Fresnel angle and the cutting tool blade angle in the outer peripheral region.
[図 8]図 8は全反射型フレネルレンズシートにおける最外周領域の説明図である。  FIG. 8 is an explanatory diagram of an outermost peripheral region in a total reflection type Fresnel lens sheet.
[図 9]図 9は外周領域における、ライズ面に対応する金型面の切削方法の説明図で ある。 [FIG. 9] FIG. 9 is an explanatory view of a cutting method of the die surface corresponding to the rise surface in the outer peripheral region. is there.
[図 10]図 10はフレネルレンズシートのライズ面における光線の説明図である。  FIG. 10 is an explanatory diagram of light rays on the rise surface of the Fresnel lens sheet.
[図 11]図 11はフレネルレンズ成型用金型の製造方法の説明図である。  FIG. 11 is an explanatory diagram of a method for manufacturing a mold for molding a Fresnel lens.
[図 12]図 12はゴースト光の説明図である。  FIG. 12 is an explanatory diagram of ghost light.
[図 13]図 13はバリの発生したフレネルレンズ成形用金型の断面図である。  FIG. 13 is a cross-sectional view of a mold for molding a Fresnel lens with burrs.
[図 14]図 14はフレネルレンズ成形用金型に形成される特定形状の頂部の説明図で ある。  FIG. 14 is an explanatory view of the top of a specific shape formed in a mold for molding a Fresnel lens.
[図 15]図 15はフレネルレンズ成形用金型における特定の頂部形状の偏在状態を示 す説明図である。  FIG. 15 is an explanatory view showing the uneven distribution state of a specific top shape in a mold for molding a Fresnel lens.
符号の説明  Explanation of symbols
[0025] 1フレネルレンズシート [0025] 1 Fresnel lens sheet
2凸レンズ  2 convex lens
10A、 10B、 10C、 10Dフレネルレンズ成形用金型  10A, 10B, 10C, 10D Fresnel lens mold
10aフレネルレンズのフレネル面に対応するフレネルレンズ成形用金型の面 10a Fresnel lens mold surface corresponding to Fresnel surface of Fresnel lens
10bフレネルレンズのライズ面に対応するフレネルレンズ成形用金型の面 10b Fresnel lens mold surface corresponding to the rise surface of the Fresnel lens
11金型原盤  11 mold master
12バリ  12 Bali
13頂部  13 top
20切削バイト  20 cutting tools
21切刃  21 cutting edge
22切刃  22 cutting blade
23切削バイトの先端部  23 Tip of cutting tool
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0026] 以下、図面を参照しつつ本発明を詳細に説明する。なお、各図中、同一符号は同 一又は同等の構成要素を表している。 Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals denote the same or equivalent components.
[0027] 本発明において、切り込み速度とは、金型原盤を旋盤で切削バイトを用いて切削す る場合に、切削バイト 20の先端部 23が金型原盤 1回転当たりに深さ (金型原板厚みIn the present invention, the cutting speed refers to the depth of the tip 23 of the cutting bit 20 per one rotation of the die master when the die master is cut with a lathe using a cutting tool (die master Thickness
)方向へ進行する距離をいう。 [0028] また、本発明にお 、て、フレネルレンズシートとは、屈折型フレネルレンズシートと全 反射型フレネルレンズシートの双方を含む。全反射型フレネルレンズシートのライズ 面とは、光の入光部及び反射部以外の面を指し、図 5に示した全反射型フレネルレ ンズシート 1では、凹凸面に描かれている面がライズ面 lbである。 ) The distance traveled in the direction. In the present invention, the Fresnel lens sheet includes both a refractive Fresnel lens sheet and a total reflection Fresnel lens sheet. The rise surface of the total reflection type Fresnel lens sheet refers to the surface other than the light incident part and the reflection part. In the total reflection type Fresnel lens sheet 1 shown in FIG. 5, the surface drawn on the uneven surface is the rise surface. lb.
[0029] 内周領域とは、図 6に示すように、金型 10を切削する切削バイト 20の刃角を θ 1 (度 )、フレネル角 0 2 (度）とした場合に、 0 1 + 0 2く 90度となる領域をいう。これに対し 、外周領域とは、図 7に示すように、 Θ 1 + Θ 2≥ 90度となる領域をいう。即ち、フレネ ルレンズでは、中心から外周に向かってフレネル角度が大きくなるので、中心から半 径方向のある点までは 0 1 + 0 2く 90度となり（内周領域）、それより外周側で 0 1 + Θ 2≥ 90度となる（外周領域)。なお、全反射型フレネルレンズシートでは、屈折型フ レネルレンズシートと比較して、シート面中におけるプリズム列の高さ、及びプリズム 列の高さに対するライズ面の長さの割合の変化が小さ 、ため、本発明で 、う内周領 域は実質上存在しない。従って、全反射型フレネルレンズシートの金型の切削時に は、後述する切り込み速度の切り替えを全面で行うことが好ま 、。  [0029] As shown in FIG. 6, the inner peripheral region is defined as 0 1 + when the blade angle of the cutting tool 20 for cutting the die 10 is θ 1 (degrees) and the Fresnel angle 0 2 (degrees). 0 2 An area that is 90 degrees. On the other hand, the outer peripheral region is a region where Θ 1 + Θ 2 ≥90 degrees as shown in FIG. That is, in the Fresnel lens, the Fresnel angle increases from the center toward the outer periphery, so a certain point in the radial direction from the center becomes 0 1 + 0 2 90 degrees (inner peripheral region), and 0 on the outer peripheral side. 1 + Θ 2≥90 degrees (outer peripheral area). The total reflection type Fresnel lens sheet has a smaller change in the height of the prism row in the sheet surface and the ratio of the rise surface length to the height of the prism row than in the refraction type Fresnel lens sheet. Therefore, in the present invention, there is substantially no inner peripheral region. Therefore, when cutting the mold of the total reflection type Fresnel lens sheet, it is preferable to switch the cutting speed described later over the entire surface.
[0030] また、最外周領域とは、同心円状に形成されたフレネルレンズの最外周及びその 近傍で、中心力も対角までの長さの外周寄り 10%の範囲をいい、特に、全反射型フ レネルレンズシートにおいては、図 8に示すように、フレネルレンズシート 1上のプリズ ム列の最も小さな半径を Rl、最も大きな半径を R2とし、その差を ROとした場合に、最 外周領域とは、最も外周寄りの ROの 10%程度の範囲をいう。  [0030] Further, the outermost peripheral region means a range in which the central force is 10% closer to the outer periphery of the outermost periphery of the Fresnel lens formed concentrically and in the vicinity thereof. In the Fresnel lens sheet, as shown in Fig. 8, when the smallest radius of the prism row on Fresnel lens sheet 1 is Rl, the largest radius is R2, and the difference is RO, the outermost peripheral area Means the range of about 10% of the outermost RO.
[0031] 図 7に示すように、外周領域では、フレネルレンズシートのフレネル面に対応する金 型面 10aを切削する切刃 21と反対側の切刃 22でライズ面に対応する金型面 10bを 切削することになる。このため、外周領域では、単に連続的に切削バイト 20を切り進 めるとライズ面が鏡面になってしまう。そこで、図 9に示すように、切削ノイト 20を斜め に切り込む。この場合、斜めの角度が大きすぎると、図 10に示すように、この金型から 得られるフレネルレンズシート 1では、レンズ面に光を入射させた場合に、不要にライ ズ lbにも光が入射し、不具合が生じるので、斜めに切り込む角度 (ライズ角 Θ 3)を大 きくすることはできない。そのため、外周領域では、内周領域に比べて切削バイト 20 を斜めに切り込む角度を小さくし、ライズ面に形成される凹凸を小さくする。したがつ て、外周領域では、金型の切り込み速度の切替により、ライズ面の凹凸のピッチに段 差が生じても、その段差は目立ちにくい。よって、本発明において、外周領域では、 金型のバリや頂部の特定形状の偏在に基づく問題と、切削速度の問題の双方の点 から、切り込み速度を切り替えることが好ましい。一方、ライズ面に目立つ段差をもた らす切り込み速度の切替はしない方が好ましぐ特に内周領域においては、切り込み 速度の大きな切替はしな 、ことが好ま 、。 [0031] As shown in FIG. 7, in the outer peripheral region, the mold surface 10b corresponding to the rise surface is formed by the cutting blade 21 opposite to the cutting surface 21 for cutting the mold surface 10a corresponding to the Fresnel surface of the Fresnel lens sheet. Will be cut. For this reason, in the outer peripheral region, if the cutting tool 20 is simply continuously cut, the rise surface becomes a mirror surface. Therefore, as shown in FIG. 9, the cutting knot 20 is cut obliquely. In this case, if the oblique angle is too large, as shown in FIG. 10, in the Fresnel lens sheet 1 obtained from this mold, when light is incident on the lens surface, light is also applied to the light lb unnecessarily. Since the incident occurs and a problem occurs, the angle (rise angle Θ 3) for cutting obliquely cannot be increased. Therefore, in the outer peripheral region, the angle at which the cutting bit 20 is cut obliquely is smaller than in the inner peripheral region, and the unevenness formed on the rise surface is reduced. Gatsutsu In the outer peripheral region, even if there is a step difference in the uneven pitch of the rise surface due to switching of the cutting speed of the mold, the step is not noticeable. Therefore, in the present invention, in the outer peripheral region, it is preferable to switch the cutting speed in terms of both a problem based on uneven burrs of the mold and the specific shape of the top and a problem of the cutting speed. On the other hand, it is preferable not to switch the cutting speed that causes a conspicuous step on the rise surface. Especially in the inner peripheral area, it is preferable not to switch the cutting speed greatly.
[0032] なお、本発明において、金型原盤としては、金型の使用形態に応じて、そのままプ レス成形に使用する場合には、硬い金属板を使用し、金型から榭脂製の成形型を製 造する場合には、切削の容易な金属板を使用する。耐久性も考慮すると、通常は、 銅、真鍮、ステンレス、ニッケル等の金属板から適宜選択される。  [0032] In the present invention, as the mold master, depending on the form of use of the mold, when used as it is for press molding, a hard metal plate is used, and the resin mold is molded from resin. When making molds, use metal plates that are easy to cut. Considering durability, it is usually selected appropriately from a metal plate such as copper, brass, stainless steel, or nickel.
[0033] 図 1は、本発明のフレネルレンズシートの製造に使用するフレネルレンズ成型用金 型 10Aの一の態様の断面説明図である。  FIG. 1 is a cross-sectional explanatory view of one embodiment of a Fresnel lens molding die 10A used for manufacturing the Fresnel lens sheet of the present invention.
[0034] このフレネルレンズ成形用金型 10Aは、図 9に示した方法と同様に、金型原盤を旋 盤で切削バイトを用いて切削する場合に、切削バイト 20として、先端部 23に 1〜3 m程度の平坦部を設けることにより耐久性を向上させたものを使用し、その一方の切 刃 21をフレネル面に対応する金型面 10aに平行に設定すると共に、切削バイト 20の 先端部 23の送り方向をライズ面に対応する金型面 10b (より詳細には、微小凹凸を 有する金型面の頂部を繋いだ面）に平行に設定し、所定の深さ Dまで切削し、フレネ ルレンズのライズ面に対応する金型面 10bに、金型の稜線に略平行な微小凹凸を筋 状に形成したものである。  [0034] Similar to the method shown in Fig. 9, this Fresnel lens molding die 10A has a cutting tool 20 with a cutting tool 20 when the mold master is cut on a lathe. Use one with improved durability by providing a flat part of ~ 3 m, and set one of the cutting edges 21 parallel to the mold surface 10a corresponding to the Fresnel surface and the tip of the cutting tool 20 Set the feed direction of the part 23 parallel to the mold surface 10b corresponding to the rise surface (more specifically, the surface connecting the tops of the mold surfaces with minute irregularities), and cut to a predetermined depth D, In the mold surface 10b corresponding to the rise surface of the Fresnel lens, minute irregularities substantially parallel to the ridge line of the mold are formed in a streak shape.
[0035] ここで、外周領域を含む領域 A2は 2通りの切り込み速度 vl μ mZ回転、 ν2 μ / 回転 (但し、 vl < v2)で切削したもので、それにより、この領域 A2では、一つのライズ 面に対応する金型面 10b内に、微小凹凸がピッチ P1 μ m、 P2 /z mの 2通りで形成さ れて 、ることを特徴として！/、る。  [0035] Here, the area A2 including the outer peripheral area is cut at two cutting speeds vl μmZ rotation and ν2 μ / rotation (provided that vl <v2). A feature is that minute irregularities are formed in the mold surface 10b corresponding to the rise surface at two pitches of P1 μm and P2 / zm! /
[0036] より詳細には、この金型 10Aは、内周領域の中心側にある領域 A1では、切削バイト 20の先端部 23の送り方向の切り込み速度を vl μ mZ回転で一定とし、外周領域を 含む領域 A2では、切り込み速度を谷底部 B1で vl μ mZ回転とし、それより頂部側の 範囲 B2で ν2 μ mZ回転（但し、 vl < v2)としたものである。これにより、中心側の領域 Alでは、ライズ面に対応する金型面 10bの微小凹凸のピッチが単一の PI μ mとなり 、外周領域を含む領域 A2では、一つのライズ面に対応する金型面 10b内の微小凹 凸のピッチが、谷底部 B1のピッチ P1 μ mと、それより頂部側の範囲 B2のピッチ P2 μ m (但し、 PI < P2)の 2通りとなっている。 More specifically, in this mold 10A, in the area A1 on the center side of the inner peripheral area, the cutting speed in the feed direction of the tip 23 of the cutting bit 20 is constant at vl μmZ rotation, and the outer peripheral area In the region A2 including, the cutting speed is vl μmZ rotation at the valley bottom B1 and ν2 μmZ rotation (where vl <v2) in the range B2 on the top side. As a result, the central area In Al, the pitch of the minute irregularities on the mold surface 10b corresponding to the rise surface is a single PI μm, and in the area A2 including the outer peripheral region, the minute irregularities in the mold surface 10b corresponding to one rise surface. There are two pitches: pitch P1 μm at valley bottom B1, and pitch P2 μm (however, PI <P2) in range B2 on the top side.
[0037] このように切り込み速度 vl、 v2を制御することにより、金型 10Aの全領域にわたり、 谷底部 B1でドゥエル切肖 lj (同心円状の個々のフレネル面内に段差が生じないように 、金型の最も深い部分では、一定の切り込み深さで、金型原盤を一回転以上回転さ せてフレネル面を研磨すること）直前、即ち、金型の最も深い部分の直前の切り込み 速度を小さくしてバリの発生を抑えることが可能となり、さらに、外周領域を含む領域 A2では、頂部側の範囲 B2に切り込み速度が大きい領域を設けることで、ライズ面の 微小凹凸の粗さを大きくしてライズ面の拡散性を大きくし、また切削時間を短縮するこ とが可能となる。 [0037] By controlling the cutting speeds vl and v2 in this way, the entire bottom of the mold 10A, the valley bottom B1 has a dwell cut lj (a step does not occur in the individual concentric Fresnel planes, At the deepest part of the mold, rotate the mold master one or more times with a constant depth of cut to polish the Fresnel surface), that is, reduce the cutting speed immediately before the deepest part of the mold. In addition, it is possible to suppress the generation of burrs.In addition, in the area A2 including the outer peripheral area, by providing an area with a high cutting speed in the area B2 on the top side, the roughness of the fine irregularities on the rise surface is increased. It is possible to increase the diffusibility of the rise surface and shorten the cutting time.
[0038] 切り込み速度 vl、 v2の具体的な好ましい数値は、金型の材質、切削バイト 20の先 端の刃角、要求されるライズ面の粗さと切削時間などにもよるが、金型の材質が真鍮 の場合、 vlは 0. 5〜2. 5 /z m/回転とするの力 S好ましく、特に、 1. 0〜2. 回 転が好ましい。 v2は 2. 0〜10 μ mZ回転とするのが好ましぐ特に、 2. 5〜6 μ / 回転が好ましい。また、この切り込み速度 v2で切削する谷底部 B1の深さ方向の範囲 は、 5〜50 μ mが好ましぐ特に 10 μ m以上として切削時間を短縮することが好まし い。  [0038] The specific preferable values of the cutting speeds vl and v2 depend on the material of the mold, the cutting edge angle of the cutting bit 20, the roughness of the rise surface required and the cutting time, etc. When the material is brass, vl is a force S of 0.5 to 2.5 / zm / rotation S, preferably 1.0 to 2 rotations. It is particularly preferable that v2 is 2.5 to 10 μmZ rotation, particularly 2.5 to 6 μm / rotation. In addition, the depth direction range of the valley bottom B1 to be cut at this cutting speed v2 is preferably 5 to 50 μm, more preferably 10 μm or more, and the cutting time is preferably shortened.
[0039] また、切り込み速度を vlとする範囲は、半径方向の位置により変化させてもよい。  [0039] The range in which the cutting speed is vl may be changed depending on the position in the radial direction.
[0040] 例えば、図 1において、切り込み速度 vl = l . 5 /z mZ回転、この速度で切削する谷 底部 B1の深さ方向の範囲 = 7 m、切り込み速度 v2 =4 mZ回転とすることで、バ リを解消させることができる。 [0040] For example, in Fig. 1, the cutting speed vl = 1.5 / z mZ rotation, the depth range of the valley bottom B1 to be cut at this speed = 7 m, and the cutting speed v2 = 4 mZ rotation. , The barrier can be eliminated.
[0041] 図 2は、本発明のフレネルレンズシートの製造に使用するフレネルレンズ成型用金 型の異なる態様の断面説明図である。このフレネルレンズ成型用金型 10Bは、内周 領域の中心側にある領域 A3では、切削バイト 20の先端部 23の送り方向の切り込み 速度を ν3 /ζ πιΖ回転で一定とし、外周領域を含む領域 Α4でも、頂部領域 Β3の切り 込み速度は v3 mZ回転で一定とし、頂部より谷底部側の範囲 B4の切り込み速度を ν4 /ζ πιΖ回転としたものである（但し、 v3 < v4) 0これにより、この金型 10B力も得られ るフレネルレンズシートは、レンズ面の全領域にわたって、金型の特定形状の頂部の 偏在に由来する同心円状の筋模様の問題が低減したものとなる。さらに、外周領域 を含む領域 A4では、切り込み速度を大きくすることにより、ライズ面の拡散性を大きく し、切削時間を短縮することができる。 FIG. 2 is a cross-sectional explanatory view of a different mode of the Fresnel lens molding die used for manufacturing the Fresnel lens sheet of the present invention. This mold 10B for forming a Fresnel lens has an area A3 on the center side of the inner peripheral area. The cutting speed in the feed direction of the tip 23 of the cutting bit 20 is constant at ν3 / ζ πιΖ rotation and includes the outer peripheral area. Even in Α4, the cutting speed of the top region Β3 is constant at v3 mZ rotation, and the cutting speed in the range B4 from the top to the valley bottom is set. ν4 / ζ πιΖ rotation (however, v3 <v4) 0 With this, the Fresnel lens sheet that can also obtain this mold 10B force is unevenly distributed at the top of the specific shape of the mold over the entire area of the lens surface. The problem of the concentric streak pattern derived from is reduced. Furthermore, in the area A4 including the outer peripheral area, by increasing the cutting speed, the diffusibility of the rise surface can be increased and the cutting time can be shortened.
[0042] 切り込み速度 v3、 v4の具体的な好ま 、数値は、金型の材質、切削バイト 20の先 端の刃角、要求されるライズ面の粗さと切削時間などにもよるが、金型の材質が真鍮 の場合、 v3は 0. 5〜2. 5 /z m/回転とするの力 子ましく、特に、 1. 0〜2. Ο μ ηι/ 転が好ましい。 ν4は 2. 5〜10 μ mZ回転とするのが好ましぐ特に、 3. 0〜6 μ / 回転が好ましい。また、この切り込み速度 v3を設ける頂部 B3の深さ方向の範囲は、 3 ピッチ程度が好ましぐそれより広い範囲に設けても、それに見合う効果は得られない [0042] The specific preference of the cutting speeds v3 and v4 depends on the die material, the cutting edge angle of the cutting tool 20, the required rise surface roughness and cutting time, etc. When the material is brass, v3 is preferably 0.5 to 2.5 / zm / rotation, and more preferably 1.0 to 2. Ομηι / rotation. ν4 is preferably 2.5 to 10 μm rotation, particularly 3.0 to 6 μm / rotation. In addition, the depth range of the top part B3 where this cutting speed v3 is provided is not as good as that even if it is provided in a wider range where about 3 pitches are preferred.
[0043] また、切り込み速度を v3とする範囲は、半径方向の位置により変化させてもよい。 [0043] Further, the range in which the cutting speed is v3 may be changed depending on the position in the radial direction.
[0044] 例えば、図 2において、切り込み速度 v3 = 1. 5 μ mZ回転、この速度 v3で切削する 頂部 B3の深さ方向の範囲 = 3 m、切り込み速度 ν4=4 /ζ πιΖ回転とすることで、金 型の特定形状の頂部の偏在に由来する同心円状の筋模様の問題を低減させること ができる。 [0044] For example, in Fig. 2, the cutting speed v3 = 1.5 μmZ rotation, cutting at this speed v3, the depth range of the top B3 = 3 m, the cutting speed ν4 = 4 / ζ πιΖ rotation Thus, it is possible to reduce the problem of the concentric streaks originating from the uneven distribution of the top of the specific shape of the mold.
[0045] 図 3のフレネルレンズ成型用金型 10Cは、内周領域と一致する領域 A1で切り込み 速度を vl μ mZ回転で一定とし、外周領域と一致する領域 A2では、切り込み速度を 谷底部 B1で vl μ mZ回転とし、それより頂部側の範囲 B2では切り込み速度を ν2 μ m Z回転（但し、 vl < v2、 PI < P2)としたものである。  [0045] The Fresnel lens molding die 10C in FIG. 3 has a constant cutting speed of vl μmZ in the area A1 that coincides with the inner peripheral area, and the cutting speed in the area A2 that coincides with the outer peripheral area. In this case, the cutting speed is ν2 μm Z rotation (however, vl <v2, PI <P2).
[0046] これにより、図 1のフレネルレンズ成型用金型 10Aと同様に、金型の全領域にわたり 、谷底部 B1で切り込み速度を小さくしてバリの発生を抑えることが可能となり、また、 外周領域に一致する領域 A2では、頂部側の範囲 B2で切り込み速度を大きくすること で、ライズ面の拡散性を大きくすると共に切削時間を短縮することが可能となる。さら に、この金型 10Cによれば、内周領域の切り込み速度が vlで一定であるため、この 金型力 得られるフレネルレンズシートにおいて、切り込み速度の切替による段差が 目立ちにくくなる。 [0047] 実際、図 3において、切り込み速度 ν1 = 2 /ζ mZ回転、この速度 vlで切削する谷底 部 B1の深さ方向の範囲 = 10 m、切り込み速度 v2 =4 mZ回転とすることで、ノ リ の発生を解消し、ライズ面における凹凸のピッチの切替段差も視認しにくかった。 [0046] As with the Fresnel lens molding die 10A in FIG. 1, this makes it possible to reduce the cutting speed at the valley bottom B1 over the entire region of the die to suppress the occurrence of burrs. In the area A2, which coincides with the area, by increasing the cutting speed in the range B2 on the top side, it becomes possible to increase the diffusibility of the rise surface and shorten the cutting time. Furthermore, according to this mold 10C, the cutting speed in the inner peripheral region is constant at vl, and therefore, the step due to the switching of the cutting speed becomes less noticeable in the Fresnel lens sheet obtained by this mold force. [0047] Actually, in FIG. 3, the cutting speed ν1 = 2 / ζ mZ rotation, the depth direction range of the valley bottom B1 to be cut at this speed vl = 10 m, the cutting speed v2 = 4 mZ rotation, The generation of glue was eliminated, and it was difficult to visually recognize the step difference in the pitch of the unevenness on the rise surface.
[0048] 図 4のフレネルレンズ成型用金型 10Dは、内周領域と一致する領域 A1で切り込み 速度を vl μ mZ回転で一定とし、外周領域と一致する領域 A2では、切り込み速度を 谷底部 B1で vl μ Ζ回転とし、頂部領域 Β3では ν3 μ mZ回転とし、谷底部 B1と頂部 領域 B3との間で切り込み速度 v2を vlや v3よりも大きくしたものである。  [0048] In the Fresnel lens molding die 10D in FIG. 4, the cutting speed is constant in the v1 μmZ rotation in the area A1 that coincides with the inner peripheral area, and the cutting speed is set in the valley bottom B1 in the area A2 that coincides with the outer peripheral area. Vl μΖ rotation, and the top region Β3 is ν3 μmZ rotation, and the cutting speed v2 between the valley bottom B1 and the top region B3 is larger than vl and v3.
[0049] これにより、金型の全領域にわたり、谷底部 B1で切り込み速度を小さくしてノ リの発 生を抑えることが可能となり、また、外周領域に一致する領域 A2では、頂部側の領域 B3の切り込み速度を小さくして、金型の特定形状の頂部の偏在に由来する問題を低 減させることができる。さらに、谷底部 B1と頂部領域 B3との間では、切り込み速度 v2 が谷底部の切り込み速度 vlや頂部領域の切り込み速度 v3より大きいので、ライズ面 の拡散性を大きくすると共に切削時間を短縮することも可能となる。また、この金型 10 Dにおいても、内周領域の切り込み速度が vlで一定であるため、この金型から得られ るフレネルレンズシートにおいて、切り込み速度の切替による段差が視認されにくい ものとなる。  [0049] This makes it possible to reduce the cutting speed at the valley bottom B1 over the entire region of the mold to suppress the generation of the nose, and in the region A2 that coincides with the outer peripheral region, the region on the top side. By reducing the cutting speed of B3, it is possible to reduce problems caused by uneven distribution of the top of the specific shape of the mold. Furthermore, between the valley bottom B1 and the top region B3, the cutting speed v2 is higher than the valley bottom cutting speed vl and the top region cutting speed v3, so that the diffusibility of the rise surface is increased and the cutting time is shortened. Is also possible. Also in this mold 10D, since the cutting speed in the inner peripheral region is constant at vl, a step due to switching of the cutting speed is difficult to be visually recognized in the Fresnel lens sheet obtained from this mold.
[0050] 例えば、図 4において、切り込み速度vl =v3 = 2 iu mZ回転、切り込み速度 vlで切 削する谷底部 B1の深さ方向の範囲 = 10 m、切り込み速度 v3で切削する頂部領域 B3の深さ方向の範囲 = 3 m、切り込み速度 v2=4 /z mZ回転とする。 [0050] For example, in Fig. 4, the depth of the valley bottom B1 to be cut at the cutting speed vl = v3 = 2 i u mZ, cutting at the cutting speed vl = 10 m, the top region B3 to be cut at the cutting speed v3 Depth range = 3 m, cutting speed v2 = 4 / z mZ rotation.
産業上の利用可能性  Industrial applicability
[0051] 本発明のフレネルレンズシートは、背面投射型テレビ、オーバーヘッドプロジェクタ 、 ノ ックライト用レンズシート、反射スクリーン等で使用することができる。 [0051] The Fresnel lens sheet of the present invention can be used in rear projection televisions, overhead projectors, knocklight lens sheets, reflective screens, and the like.

Claims

請求の範囲 The scope of the claims
[1] レンズ面の少なくとも最外周領域において、一つのライズ面内に、フレネルレンズの 稜線に沿った微小凹凸が異なるピッチで形成されているフレネルレンズシート。  [1] A Fresnel lens sheet in which minute irregularities along a ridge line of a Fresnel lens are formed at different pitches in one rise surface in at least the outermost peripheral region of the lens surface.
[2] レンズ面の少なくとも最外周領域のライズ面について、フレネルレンズ成形用金型の 谷底部に対応する部分の微小凹凸のピッチを P1、それより頂部側に対応する部分の 微小凹凸のピッチを P2とした場合に、 PI < P2である請求項 1記載のフレネルレンズ シート。  [2] For the rise surface in at least the outermost peripheral area of the lens surface, P1 is the pitch of the fine irregularities in the part corresponding to the valley bottom of the mold for Fresnel lens molding, and 2. The Fresnel lens sheet according to claim 1, wherein PI <P2 when P2.
[3] レンズ面の少なくとも最外周領域のライズ面について、フレネルレンズ成形用金型の 頂部に対応する部分の微小凹凸のピッチを P3、それより谷底部側に対応する部分の 微小凹凸のピッチを P4とした場合に、 P3く P4である請求項 1又は 2記載のフレネル レンズシート。  [3] For the rise surface in at least the outermost peripheral area of the lens surface, P3 is the pitch of the minute irregularities corresponding to the top of the mold for molding the Fresnel lens, and the pitch of the minute irregularities corresponding to the bottom of the valley from that P3. The Fresnel lens sheet according to claim 1 or 2, wherein P4 is P4 when P4 is set.
[4] レンズ面の内周領域のライズ面において、微小凹凸が単一のピッチで形成されてい る請求項 1〜3のいずれかに記載のフレネルレンズシート。  [4] The Fresnel lens sheet according to any one of [1] to [3], wherein minute irregularities are formed at a single pitch on a rise surface in an inner peripheral region of the lens surface.
[5] 金型原盤を旋盤で切削バイトを用いて切削したフレネルレンズ成形用金型カゝらフレ ネルレンズシートを製造する方法であって、フレネルレンズ成形用金型として、少なく とも最外周領域において、フレネルレンズのライズ面に対応する金型面が 2通りの切 り込み速度で切削されているものを使用するフレネルレンズシートの製造方法。 [5] A method of manufacturing a Fresnel lens molding die, which is obtained by cutting a die master using a cutting tool with a lathe, and at least the outermost peripheral region as a Fresnel lens molding die Method for manufacturing a Fresnel lens sheet using a die surface corresponding to the rise surface of the Fresnel lens cut at two cutting speeds.
[6] フレネルレンズの少なくとも最外周領域において、ライズ面に対応する金型面の谷底 部の切り込み速度 vl、それより頂部側の切り込み速度を v2とした場合に、 vl <v2であ る請求項 5記載のフレネルレンズシートの製造方法。 [6] In the case where at least the outermost peripheral region of the Fresnel lens has a cutting speed vl at the valley bottom of the mold surface corresponding to the rise surface, and v2 is a cutting speed at the top of the die, vl <v2 5. A method for producing a Fresnel lens sheet according to 5.
[7] フレネルレンズの少なくとも最外周領域において、ライズ面に対応する金型面の頂部 の切り込み速度を v3、それより谷底部側の切り込み速度を v4とした場合に、 v3<v4で ある請求項 5又は 6記載のフレネルレンズシートの製造方法。 [7] In at least the outermost peripheral region of the Fresnel lens, v3 <v4 when the cutting speed at the top of the mold surface corresponding to the rise surface is v3 and the cutting speed at the bottom of the valley is v4. 5. A method for producing a Fresnel lens sheet according to 5 or 6.
[8] フレネルレンズ成形用金型の内周領域の切り込み速度が一定である請求項 5〜7の いずれかに記載のフレネルレンズシートの製造方法。 [8] The method for producing a Fresnel lens sheet according to any one of [5] to [7], wherein the cutting speed of the inner peripheral region of the mold for molding the Fresnel lens is constant.
PCT/JP2007/056321 2006-03-28 2007-03-27 Fresnel lens sheet WO2007116716A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011175076A (en) * 2010-02-24 2011-09-08 Olympus Corp Fresnel lens and fresnel lens molding die, and method for manufacturing fresnel lens and method for manufacturing fresnel lens molding die
JP2015068979A (en) * 2013-09-27 2015-04-13 大日本印刷株式会社 Reflection type screen, video display device, molding block of lens layer of reflection type screen

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JPH04127101A (en) * 1990-09-19 1992-04-28 Hitachi Ltd Fresnel lens
JPH06347614A (en) * 1993-06-07 1994-12-22 Nippon Tokushu Kogaku Jushi Kk Structure of fresnel lens
JP2002239802A (en) * 2000-12-11 2002-08-28 Dainippon Printing Co Ltd Working method of metal mold for fresnel lens, tool to be used therefor, and metal mold and fresnel lens worked by this working method

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
JPH04127101A (en) * 1990-09-19 1992-04-28 Hitachi Ltd Fresnel lens
JPH06347614A (en) * 1993-06-07 1994-12-22 Nippon Tokushu Kogaku Jushi Kk Structure of fresnel lens
JP2002239802A (en) * 2000-12-11 2002-08-28 Dainippon Printing Co Ltd Working method of metal mold for fresnel lens, tool to be used therefor, and metal mold and fresnel lens worked by this working method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011175076A (en) * 2010-02-24 2011-09-08 Olympus Corp Fresnel lens and fresnel lens molding die, and method for manufacturing fresnel lens and method for manufacturing fresnel lens molding die
JP2015068979A (en) * 2013-09-27 2015-04-13 大日本印刷株式会社 Reflection type screen, video display device, molding block of lens layer of reflection type screen

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