JPH1123814A - Optical control sheet and its manufacture - Google Patents
Optical control sheet and its manufactureInfo
- Publication number
- JPH1123814A JPH1123814A JP17579397A JP17579397A JPH1123814A JP H1123814 A JPH1123814 A JP H1123814A JP 17579397 A JP17579397 A JP 17579397A JP 17579397 A JP17579397 A JP 17579397A JP H1123814 A JPH1123814 A JP H1123814A
- Authority
- JP
- Japan
- Prior art keywords
- sheet
- sheet surface
- temperature
- light
- heating
- Prior art date
- Legal status (The legal status 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 status listed.)
- Pending
Links
Landscapes
- Optical Elements Other Than Lenses (AREA)
- Shaping Of Tube Ends By Bending Or Straightening (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、エンボス形状を転
写された熱可塑性樹脂シートよりなる光制御シート及び
その製造方法に関し、特に、液晶表示装置の光源部に用
いられる光御シート及びその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light control sheet made of a thermoplastic resin sheet to which an embossed shape has been transferred, and a method of manufacturing the same. About.
【0002】[0002]
【従来の技術】通常、液晶表示画面は自家発光性を持た
ないため、従来より、液晶表示素子の背面から光を当て
るバックライトユニットと呼ばれる光源ユニットが用い
られており、最近では、光源の位置を液晶表示装置の側
面に配したエッジライト方式が多く用いられている。2. Description of the Related Art Generally, a liquid crystal display screen does not have a self-luminous property. Therefore, a light source unit called a backlight unit that shines light from the back of a liquid crystal display element has been conventionally used. Are often used on the side of a liquid crystal display device.
【0003】エッジライト方式に用いられる面状光源装
置は、図5に示すような透明な導光板(1)の一方の側
面に光源として蛍光管(2)が配されており、導光板の
背面には塗料のドットパターン(3)が形成されてお
り、導光板の後側には反射板(4)が配されている。こ
のドットパターンにより、側面の蛍光管から入射した光
を、導光板から画面の所望の位置で表面側へ出射させる
ことができる。In a planar light source device used in the edge light system, a fluorescent tube (2) is disposed as a light source on one side surface of a transparent light guide plate (1) as shown in FIG. Is formed with a paint dot pattern (3), and a reflection plate (4) is arranged behind the light guide plate. With this dot pattern, light incident from the fluorescent tube on the side surface can be emitted from the light guide plate to the front side at a desired position on the screen.
【0004】ところで、図6に示したごとく、蛍光管
(2)から発せられドットパターン(3)によって導光
板(1)から出射された光のほとんどは、出射光パター
ン(5)のような導光板の法線方向から大きく外れた方
向へ出射された分布となる。したがって、導光板の法線
方向より画面を見る使用者にとっては得られる光量が少
なく、液晶表示画面が非常に暗く感じてしまう。By the way, as shown in FIG. 6, most of the light emitted from the fluorescent tube (2) and emitted from the light guide plate (1) by the dot pattern (3) is guided by a light guide pattern (5). The distribution is emitted in a direction largely deviated from the normal direction of the light plate. Therefore, a user who views the screen from the normal direction of the light guide plate obtains a small amount of light, and feels the liquid crystal display screen very dark.
【0005】通常、この欠点を解消するために、導光板
の前面に光制御シートを配し、不要な斜め方向の出射光
量を抑えるという方法がとられる。従来の光制御シート
としては、熱可塑性樹脂シート表面に粗度Ra=100
〜500μm程度の微細なランダム凹凸を形成させたも
のが知られている(特開昭62−291618号公
報)。だが、粗度が大きいランダム凹凸では、依然とし
て斜め方向の出射光量が多くバックライトの高輝度化に
限界があった。そこで、本出願人は以前に図7に示した
ようなシート表面に断面がほぼ三角形の多数の凸部
(6)と溝(7)からなるピッチ200μm、深さ12
0μmのプリズム形状の凸部が平行状の配置で転写され
ており、かつシート背面に50μmのコーティング層が
設けられたシートを発明し、集光性と出射光量を共に改
善したものを出願している(特開平7−230001号
公報)。(以下、このような、熱可塑性樹脂シートの表
面にプリズム形状の加工を施したシートを「 プリズムシ
ート」 と呼ぶ。)Usually, in order to solve this drawback, a method of arranging a light control sheet on the front surface of the light guide plate and suppressing unnecessary light emission in the oblique direction is adopted. As a conventional light control sheet, the surface of the thermoplastic resin sheet has a roughness Ra = 100.
There is known one having fine random irregularities of about 500 μm (JP-A-62-291618). However, in the case of random irregularities having a large roughness, the amount of emitted light in the oblique direction is still large, and there is a limit to increasing the brightness of the backlight. Therefore, the applicant has previously described a sheet surface such as that shown in FIG.
Invented a sheet in which 0 μm prism-shaped projections were transferred in parallel arrangement and provided with a 50 μm coating layer on the back of the sheet, and filed an application that improved both the light-collecting property and the amount of emitted light. (JP-A-7-230001). (Hereinafter, such a sheet in which the surface of a thermoplastic resin sheet is processed into a prism shape is referred to as a “prism sheet”.)
【0006】[0006]
【発明が解決しようとする課題】ところで、なお、プリ
ズムシートにはプリズムの凸部のピッチが100〜20
0μmと粗いため、プリズムにより生じた光の濃淡が目
視でき、スジ状に画面がギラついて見えるという問題が
あった。このギラツキは、凸部のピッチを100μm未
満に細かくすれば、プリズムにより生じる光の濃淡が目
視できなくなり、画面のギラツキも生じなくなる。しか
しながら、従来公知のプリズムシートの製造方法( 注
型、溶剤キャスティング、異型押出法、押出成形しなが
らのロールエンボッシング法、平板による熱プレス法、
モノマーキャスチング法、射出成形法など)では、溶融
樹脂の表面張力の影響が無視できなくなるため凸部のピ
ッチを100μm未満に細かくすることは不可能あるい
は非常に困難であった。Incidentally, the pitch of the projections of the prism is 100 to 20 on the prism sheet.
Due to the coarseness of 0 μm, there is a problem that the light and shade of light generated by the prism can be visually observed, and the screen appears to be streaky. If the pitch of the projections is reduced to less than 100 μm, the light and shade of the light generated by the prism cannot be visually observed, and the screen does not cause the glare. However, conventionally known methods for producing a prism sheet (casting, solvent casting, profile extrusion, roll embossing while extrusion, hot pressing with a flat plate,
In the monomer casting method, the injection molding method, and the like), the influence of the surface tension of the molten resin cannot be ignored, and it has been impossible or very difficult to reduce the pitch of the projections to less than 100 μm.
【0007】本発明者は、これまでの製造方法が成形圧
力の制御等の工夫が中心であり、溶融樹脂の表面張力と
密接に関わる加熱温度制御の詳細な検討まではされてい
なかった点に着目して、溶融樹脂温度とシート表面の加
熱条件との間に表面張力の影響を抑制するための特定の
関係があることを見出し、本発明を完成するに到った。
すなわち、本発明はシートの加熱量と加熱時間を制御す
ることによって、液晶表示装置に用いた場合に正面方向
が十分明るくなるような集光性を持ち、かつ、画面にギ
ラツキを生じないバックライトユニット用の光制御シー
トを提供することを目的とする。The present inventor has pointed out that the conventional manufacturing method has mainly been devised such as control of the molding pressure, and has not been studied in detail of the heating temperature control closely related to the surface tension of the molten resin. By focusing attention, it has been found that there is a specific relationship between the molten resin temperature and the heating condition of the sheet surface for suppressing the influence of surface tension, and the present invention has been completed.
That is, the present invention controls the heating amount and the heating time of the sheet, so that when used in a liquid crystal display device, the backlight has a light-collecting property such that the front direction becomes sufficiently bright and does not cause glare on the screen. It is an object to provide a light control sheet for a unit.
【0008】[0008]
【課題を解決するための手段】請求項1に記載の発明は
断面がほぼ三角形の多数のプリズム形状がシート表面に
形成された熱可塑性樹脂シートよりなる光制御シートで
あって、シート表面に形成された多数の凸部のピッチが
50μm以上100μm未満であることを特徴とする光
制御シートである。According to a first aspect of the present invention, there is provided a light control sheet comprising a thermoplastic resin sheet having a large number of prisms each having a substantially triangular cross section formed on the sheet surface. The light control sheet is characterized in that the pitch of the large number of projected portions is not less than 50 μm and less than 100 μm.
【0009】請求項1に記載の発明における熱可塑性樹
脂シートの材質は特に限定されないが、光制御シートと
しては、ポリカーボネート、ポリメチルメタクリレー
ト、ポリサルホン、ポリエーテルサルホン、ポリアリレ
ート、ポリエーテルイミド、ポリメチルペンテン、非晶
性共重合ポリエステルなどの光透過性の良好な樹脂材が
好適である。ピッチの測定は隣り合うプリズムの間の凸
部の頂点間の距離を求めることにより行う。プリズムシ
ートのピッチは50μm以上100μm未満でなければ
ならない。ピッチが100μm以上であると、バックラ
イトに組み込まれたプリズムシートにスジ状のギラツキ
が生じて視認性が悪くなる。ピッチが50μm未満であ
ると、エンボス形状の転写の際により精密なシートの温
度調節を必要とするためシートを安定して製造すること
ができない。The material of the thermoplastic resin sheet in the first aspect of the present invention is not particularly limited. Examples of the light control sheet include polycarbonate, polymethyl methacrylate, polysulfone, polyethersulfone, polyarylate, polyetherimide, and polyetherimide. A resin material having good light transmittance, such as methylpentene and amorphous copolyester, is suitable. The pitch is measured by obtaining the distance between the vertices of the convex portions between the adjacent prisms. The pitch of the prism sheet must be 50 μm or more and less than 100 μm. If the pitch is 100 μm or more, a streak-like glare is generated on the prism sheet incorporated in the backlight, and visibility is deteriorated. If the pitch is less than 50 μm, it is necessary to more precisely control the temperature of the sheet during the transfer of the embossed shape, so that the sheet cannot be manufactured stably.
【0010】請求項2に記載の発明は熱可塑性樹脂シー
ト表面を加熱軟化させ、次いでシート表面に所望のエン
ボス形状の50μm以上100μm未満の逆凹凸パター
ンを有する版を圧着して、エンボス形状を転写する光制
御シートの製造方法において、前記熱可塑性樹脂のガラ
ス転移温度をTg℃としたとき、版を圧着する直前のシ
ート表面温度がTg℃以上、シート中心温度が(Tg−
10)℃以下でかつ、シート表面を加熱軟化させる際に
シート表面に与えられる熱量QkW/m2 と加熱時間t
秒が以下の関係を満たすように加熱することを特徴とす
る光制御シートの製造方法である。 10<Q<1000 かつ 10/Q<t<100/Q[0010] According to the second aspect of the present invention, the surface of the thermoplastic resin sheet is heated and softened, and then a plate having a reverse embossed pattern having a desired embossed shape of 50 µm or more and less than 100 µm is pressed on the sheet surface to transfer the embossed shape. When the glass transition temperature of the thermoplastic resin is Tg ° C., the sheet surface temperature immediately before pressing the plate is Tg ° C. or higher, and the sheet central temperature is (Tg−
10) The amount of heat QkW / m 2 given to the sheet surface when heating and softening the sheet surface at a temperature of not more than 0 ° C. and the heating time t
A method for manufacturing a light control sheet, characterized in that heating is performed so that seconds satisfy the following relationship. 10 <Q <1000 and 10 / Q <t <100 / Q
【0011】請求項2に記載の発明における熱可塑性樹
脂シートの材質は特に限定されないが、光制御シートと
しては、ポリカーボネート、ポリメチルメタクリレート
などの光透過性の良好な樹脂材が好適である。熱可塑性
樹脂シートの製造方法は、押出成形法、射出成形法、溶
剤キャスティング法、モノマーキャスティング法などが
あるが、これらに限定されない。版を圧着する直前のシ
ート表面温度はTg℃以上、シート中心温度は(Tg−
10)℃以下でなければならない。シート表面温度がT
gより低いとシート表面は塑性変形し難くエンボス転写
性が悪くなる。また、シート中心温度が(Tg−10)
℃を超えると、版を圧着する圧力が面方向の樹脂流動に
も使われ、実質的にシート表面の塑性変形に使われる圧
力は版を圧着する圧力よりも大幅に低下し、繊細なピッ
チの凹凸の転写ができにくくなる。エンボス転写でのシ
ート表面とシート中心の温度の測定は、熱電対をシート
表面とシート中心に貼り付けたシートを用いてあらかじ
め各加熱条件で実測しておき、所望の温度範囲内にシー
トの温度を納められるようする。The material of the thermoplastic resin sheet in the second aspect of the present invention is not particularly limited. However, as the light control sheet, a resin material having good light transmittance, such as polycarbonate and polymethyl methacrylate, is preferable. The method for producing the thermoplastic resin sheet includes, but is not limited to, an extrusion molding method, an injection molding method, a solvent casting method, and a monomer casting method. The sheet surface temperature immediately before pressing the plate is Tg ° C. or higher, and the sheet center temperature is (Tg−
10) It must be below ° C. Sheet surface temperature is T
If it is less than g, the sheet surface is unlikely to be plastically deformed and the emboss transferability is deteriorated. Also, the sheet center temperature is (Tg-10)
When the temperature exceeds ℃, the pressure for pressing the plate is also used for the resin flow in the surface direction, and the pressure used for the plastic deformation of the sheet surface is substantially lower than the pressure for pressing the plate. It becomes difficult to transfer irregularities. The temperature of the sheet surface and the center of the sheet in the emboss transfer is measured under each heating condition in advance using a sheet in which a thermocouple is attached to the sheet surface and the center of the sheet, and the temperature of the sheet is set within a desired temperature range. So that it can be stored.
【0012】シート表面を加熱する方法は、熱風、赤外
線ヒーター、ハロゲンランプヒーター等の非接触加熱、
加熱ロール、熱板等の接触加熱があるが特に限定されな
い。シート表面の加熱の方法は、シート表面を加熱軟化
させる際にシート表面に与えられる熱量QkW/m2 と
加熱時間t秒が10<Q<1000 かつ 10/Q<
t<100/Qの関係式を満たすように加熱する。Qが
10kW/m2 以下の時は、加熱量が低すぎてシート表
面の温度とシート中心温度の差が小さくなる。Qが10
00kW/m2 以上では、シート表面の温度が急上昇
し、シート表面の樹脂が酸化・熱分解により劣化・変色
する恐れがある。また、10/Q<t<100/Qは実
験により得られた関係式であって、特に単位はない。こ
の関係において加熱時間tが(10/Q)秒以下の時は
シート表面温度がTg以上まで上がらず、シート表面が
塑性変形し難いため、エンボス転写性が悪くなる。tが
(100/Q)秒以上では、シートの温度が均一化して
しまい、シート中心温度が(Tg−10)℃より高くな
り、圧着圧力を実質的に低下させ繊細なピッチの凹凸を
転写できない。The method of heating the sheet surface includes non-contact heating such as hot air, an infrared heater, a halogen lamp heater, and the like.
There is contact heating of a heating roll, a hot plate or the like, but there is no particular limitation. The method of heating the sheet surface is such that when the sheet surface is heated and softened, the amount of heat QkW / m 2 applied to the sheet surface and the heating time t seconds are 10 <Q <1000 and 10 / Q <
The heating is performed so as to satisfy the relational expression of t <100 / Q. When Q is 10 kW / m 2 or less, the heating amount is too low, and the difference between the sheet surface temperature and the sheet center temperature becomes small. Q is 10
If it is more than 00 kW / m 2 , the temperature of the sheet surface will rise rapidly, and the resin on the sheet surface may be degraded or discolored by oxidation or thermal decomposition. Further, 10 / Q <t <100 / Q is a relational expression obtained by an experiment, and there is no particular unit. In this relation, when the heating time t is (10 / Q) seconds or less, the sheet surface temperature does not rise to Tg or more, and the sheet surface is hardly plastically deformed, so that the emboss transferability deteriorates. When t is (100 / Q) seconds or more, the temperature of the sheet becomes uniform, the center temperature of the sheet becomes higher than (Tg-10) ° C., and the pressure for bonding is substantially reduced, so that fine pitch irregularities cannot be transferred. .
【0013】このように加熱軟化させたシート表面にエ
ンボス形状を転写する成形法としては、従来公知のロー
ルエンボッシング法、平板への熱プレス法等があるが、
いずれも使用でき特に限定されない。 (作用)本発明により、凸部のピッチが100μm未満
のプリズムシートを安定的に効率よく製造することによ
り、プリズムにより生じる光の濃淡が目視できなくなり
正面方向に十分に明るく、かつギラツキを生じない液晶
画面提供することができる。As a molding method for transferring an embossed shape to the surface of the sheet softened by heating as described above, there are a conventionally known roll embossing method and a hot press method for a flat plate.
Any of them can be used and is not particularly limited. (Function) According to the present invention, by stably and efficiently producing a prism sheet having a convex portion pitch of less than 100 μm, the light and shade of light generated by the prism cannot be visually observed, and the light is sufficiently bright in the front direction and no glare occurs. LCD screen can be provided.
【0014】[0014]
【発明の実施の形態】以下実施例を説明する。 実施例1 Tg=150℃、熱伝導率λ=1.9×10-4kW/m
℃のポリカーボネート樹脂をTダイより溶融押出し、冷
却ロール上で冷却し、厚さ0.1mm及び0.2mmの
2種類のシートを作成した。厚さ0.1mmのシートを
2枚重ね合わせ、表面と中間に線径0.2mmのK熱電
対を貼り付け、250℃の熱風オーブンに通し、1秒間
加熱し、シート表面及び中心温度を測定した。この時の
表面と中心の温度差は最大40℃であった。ところで、
シート表面に与えられた熱量QkW/m2 の算出は、ま
ず、熱電対をシート表面とシート中心に貼り付け加熱工
程のシート表面とシート中心の温度差ΔT℃の最大値を
実測したあと、このシートの熱伝導率λkW/m℃と、
シート厚みの半分にあたる二本の熱電対の距離dmm、
及びΔT℃をQ=λ・ΔT/dに代入する方法で行っ
た。この方法でシート表面に与えられた熱量を計算する
と、Q=76kW/m2 であった。また、加熱開始0.
2秒後のシート表面の温度は160℃、中心温度は13
0℃であった。次に、厚さ0.2mmのシートを250
℃の熱風オーブンに通し、0.2秒間加熱後ただちに、
表面温度140℃、周方向に多数の溝を切った冷却ロー
ルでプレスし、MDに多数の凸部を有する光制御シート
を得た。使用した冷却ロールの溝の断面形状は図4に示
す通りで、溝の深さ、25μm、溝の頂角は90°、溝
のピッチは50μmである。得られたシートの断面形状
は図1に示すとおりで、溝深さは23μm、溝の頂角は
90°、凸部のピッチは50μm、凸部の曲率半径は6
μmであった。Embodiments of the present invention will be described below. Example 1 Tg = 150 ° C., thermal conductivity λ = 1.9 × 10 −4 kW / m
C. The polycarbonate resin at a temperature of .degree. C. was melt-extruded from a T-die and cooled on a cooling roll to prepare two types of sheets having a thickness of 0.1 mm and 0.2 mm. Two sheets of 0.1mm thickness are stacked, a K thermocouple with a wire diameter of 0.2mm is stuck between the surface and the middle, passed through a 250 ° C hot air oven and heated for 1 second to measure the sheet surface and center temperature did. At this time, the temperature difference between the surface and the center was 40 ° C. at the maximum. by the way,
The calorific value QkW / m 2 given to the sheet surface was calculated by first measuring the maximum value of the temperature difference ΔT ° C. between the sheet surface and the sheet center in the heating step by attaching a thermocouple to the sheet surface and the sheet center. The thermal conductivity of the sheet λkW / m ° C;
The distance dmm between two thermocouples corresponding to half of the sheet thickness,
And ΔT ° C. were substituted into Q = λ · ΔT / d. When the amount of heat applied to the sheet surface by this method was calculated, Q = 76 kW / m 2 . In addition, heating was started at 0.
After 2 seconds, the temperature of the sheet surface is 160 ° C. and the central temperature is 13 ° C.
It was 0 ° C. Next, a sheet having a thickness of 0.2 mm was
℃ hot air oven, immediately after heating for 0.2 seconds,
Pressing was performed with a cooling roll having a surface temperature of 140 ° C. and a large number of grooves formed in the circumferential direction to obtain a light control sheet having a large number of convex portions on the MD. The cross-sectional shape of the groove of the cooling roll used is as shown in FIG. 4, the depth of the groove is 25 μm, the vertex angle of the groove is 90 °, and the pitch of the groove is 50 μm. The cross-sectional shape of the obtained sheet is as shown in FIG. 1, the groove depth is 23 μm, the apex angle of the groove is 90 °, the pitch of the projections is 50 μm, and the radius of curvature of the projections is 6
μm.
【0015】性能試験 評価方法として、JCS−C7614の輝度測定を行っ
た。図8において、光源として太さ35mm、長さ13
5mmの蛍光管(2)が、背面にドットパターン(3)
を有する導光板(1)の側面に配されている。導光板
(1)は厚さ3mm、横205mm、縦135mmのポ
リメチルメタクリレート板からなる。導光板(1)の後
側には反射板(4)が配され、導光板(1)の前側には
光制御シート(S)を配した。また、光制御シート
(S)に前側には液晶表示素子(8)が配置されてい
る。反射板は不透明なポリエチレンテレフタレート製の
フィルムからなる。上記各構成のエッジ一灯式バックラ
イトにおいて、印可電圧12Vでの法線方向輝度を測定
したところ、500cd/m2 であった。また、画面に
はギラツキ等の視認上の問題はなかった。Performance test As an evaluation method, luminance measurement of JCS-C7614 was performed. In FIG. 8, the light source has a thickness of 35 mm and a length of 13 mm.
5mm fluorescent tube (2), dot pattern (3) on the back
The light guide plate (1) having The light guide plate (1) is made of a polymethyl methacrylate plate having a thickness of 3 mm, a width of 205 mm, and a length of 135 mm. A reflection plate (4) was arranged on the rear side of the light guide plate (1), and a light control sheet (S) was arranged on the front side of the light guide plate (1). Further, a liquid crystal display element (8) is disposed on the front side of the light control sheet (S). The reflector is made of an opaque polyethylene terephthalate film. When the luminance in the normal direction at an applied voltage of 12 V was measured for the edge-light type backlight of each configuration described above, it was 500 cd / m 2 . In addition, there was no visual problem such as glare on the screen.
【0016】比較例1 実施例1と同様に0.1mmのシートを2枚重ね合わ
せ、表面と中間に線径0.2mmのK熱電対を貼付け、
250℃の熱風オーブンに通し、1秒間加熱し、シート
表面および中心温度を測定した。シート表面に与えられ
た熱量は実施例1と同様にQ=76kW/m2 であっ
た。また、加熱開始0.1秒後のシート表面温度は14
0℃、中心温度は100℃であった。次に、厚さ0.2
mmのシートを250℃の熱風オーブンに通し、加熱時
間を0.1秒とした以外は実施例1と同様にして、MD
に多数の凸条を有する光制御シートを得た。得られたシ
ートの断面形状は図2に示すとおりで、溝深さは15μ
m凸上の頂角は90°凸部のピッチは50μm、凸部の
曲率半径は25μmであった。また、実施例1と同様に
して輝度測定を行ったところ、法線方向輝度は、400
cd/m2 と暗く、視認性は不良であった。COMPARATIVE EXAMPLE 1 Two sheets each having a thickness of 0.1 mm were superposed in the same manner as in Example 1, and a K thermocouple having a wire diameter of 0.2 mm was attached between the surface and the middle.
The sheet was passed through a hot air oven at 250 ° C., heated for 1 second, and the sheet surface and center temperatures were measured. The amount of heat applied to the sheet surface was Q = 76 kW / m 2 as in Example 1. The sheet surface temperature 0.1 second after the start of heating is 14
The temperature was 0 ° C. and the central temperature was 100 ° C. Next, thickness 0.2
mm sheet was passed through a hot air oven at 250 ° C. and the heating time was changed to 0.1 second in the same manner as in Example 1 except that the heating time was changed to 0.1 second.
A light control sheet having a large number of ridges was obtained. The cross-sectional shape of the obtained sheet is as shown in FIG. 2, and the groove depth is 15 μm.
The vertex angle on the m-projection was 90 °, the pitch of the projections was 50 μm, and the radius of curvature of the projections was 25 μm. When the luminance was measured in the same manner as in Example 1, the luminance in the normal direction was 400
It was as dark as cd / m 2 and visibility was poor.
【0017】比較例2 実施例1と同様に0.1mmのシートを2枚重ね合わ
せ、表面と中間に線径0.2mmのK線熱電対を貼付
け、250℃の熱風オーブンに通し、1秒間加熱し、シ
ート表面および中心温度を測定した。シート表面に与え
られた熱量は実施例1と同様にQ=76kW/m2 であ
った。また、加熱開始2秒後のシート表面温度は250
℃、中心温度は240℃であった。次に、厚さ0.2m
mのシートを250℃の熱風オーブンに通し、加熱時間
を2秒とした以外は実施例1と同様にして、MDに多数
の凸条を有する光制御シートを得た。得られたシートの
断面形状は図3に示すとおりで、溝深さは20μm、凸
条の頂角は90°凸部のピッチは50μm、凸部の曲率
半径は15μmであった。また、実施例1と同様にして
輝度測定を行ったところ、法線方向輝度は、450cd
/m2 と暗く、視認性は不良であった。Comparative Example 2 In the same manner as in Example 1, two sheets each having a thickness of 0.1 mm were overlapped, a K-line thermocouple having a wire diameter of 0.2 mm was attached between the surface and the middle, and passed through a hot-air oven at 250 ° C. for 1 second. The sheet was heated and the sheet surface and center temperatures were measured. The amount of heat applied to the sheet surface was Q = 76 kW / m 2 as in Example 1. The sheet surface temperature 2 seconds after the start of heating is 250
° C and the central temperature was 240 ° C. Next, thickness 0.2m
m was passed through a hot-air oven at 250 ° C., and the light control sheet having many convex stripes in the MD was obtained in the same manner as in Example 1 except that the heating time was changed to 2 seconds. The cross-sectional shape of the obtained sheet was as shown in FIG. 3, the groove depth was 20 μm, the apex angle of the ridge was 90 °, the pitch of the ridges was 50 μm, and the radius of curvature of the ridges was 15 μm. When the luminance was measured in the same manner as in Example 1, the luminance in the normal direction was 450 cd.
/ M 2 and the visibility was poor.
【0018】以上の結果を表1に示す。Table 1 shows the results.
【表1】 [Table 1]
【発明の効果】本発明により、凸部のピッチが100μ
m未満のプリズムシートを安定的に効率よく製造するこ
とができる。また、本発明により、液晶表示装置に用い
た場合に正面方向が十分に明るくなるような集光性を持
ち、かつ、画面にギラツキを生じないバックライトユニ
ット用の光制御シートを提供することができる。According to the present invention, the pitch of the projections is 100 μm.
m can be stably and efficiently manufactured. Further, according to the present invention, it is possible to provide a light control sheet for a backlight unit which has a light-collecting property such that the front direction becomes sufficiently bright when used in a liquid crystal display device and does not cause glare on a screen. it can.
【0019】[0019]
【図1】実施例1で得られた光制御シートの凸部の形状
を示す幅方向の断面図FIG. 1 is a cross-sectional view in the width direction showing a shape of a convex portion of a light control sheet obtained in Example 1.
【図2】比較例1で得られた光制御シートの凸部の形状
を示す幅方向の断面図FIG. 2 is a cross-sectional view in the width direction showing a shape of a convex portion of the light control sheet obtained in Comparative Example 1.
【図3】比較例2で得られた光制御シートの凸部の形状
を示す幅方向の断面図FIG. 3 is a cross-sectional view in the width direction showing a shape of a convex portion of the light control sheet obtained in Comparative Example 2.
【図4】実施例1で光制御シート成形に用いた圧着用の
冷却ロールの溝の形状を示す断面図FIG. 4 is a cross-sectional view showing the shape of the groove of the cooling roll for pressure bonding used for molding the light control sheet in Example 1.
【図5】エッジライト方式のバックライトユニットの概
略図FIG. 5 is a schematic diagram of an edge light type backlight unit.
【図6】導光板単体での出射光特性を示す概略図FIG. 6 is a schematic diagram showing emission light characteristics of the light guide plate alone.
【図7】プリズムシート方式の光制御シートの一例FIG. 7 shows an example of a prism sheet type light control sheet.
【図8】光制御シートの性能試験に用いられた光源ユニ
ットを示す概略図FIG. 8 is a schematic diagram showing a light source unit used for a performance test of the light control sheet.
1・・・導光板 2・・・蛍光管 3・・・ドットパターン 4・・・反射板 5・・・出射光パターン分布 6・・・プリズムシートの凸部 7・・・プリズムシートの溝 8・・・液晶表示素子 S・・・光制御シート DESCRIPTION OF SYMBOLS 1 ... Light guide plate 2 ... Fluorescent tube 3 ... Dot pattern 4 ... Reflector 5 ... Outgoing light pattern distribution 6 ... Convex part of a prism sheet 7 ... Groove of a prism sheet 8 ... Liquid crystal display element S ... Light control sheet
Claims (2)
がシート表面に形成された熱可塑性樹脂シートよりなる
光制御シートであって、シート表面に形成された多数の
凸部のピッチが50μm以上100μm未満であること
を特徴とする光制御シート。1. A light control sheet comprising a thermoplastic resin sheet having a large number of prisms each having a substantially triangular cross section formed on a sheet surface, wherein a pitch of a large number of convex portions formed on the sheet surface is 50 μm or more and 100 μm or more. A light control sheet, wherein:
せ、次いでシート表面に所望のエンボス形状の50μm
以上100μm未満の逆凹凸パターンを有する版を圧着
して、エンボス形状を転写する光制御シートの製造方法
において、前記熱可塑性樹脂のガラス転移温度をTg℃
としたとき、版を圧着する直前のシート表面温度がTg
℃以上、シート中心温度が(Tg−10)℃以下でか
つ、シート表面を加熱軟化させる際にシート表面に与え
られる熱量QkW/m2 と加熱時間t秒が以下の関係を
満たすように加熱することを特徴とする光制御シートの
製造方法。 10<Q<1000 かつ 10/Q<t<100/Q2. The surface of the thermoplastic resin sheet is heated and softened, and then the desired embossed shape of 50 μm is formed on the sheet surface.
In the method for producing a light control sheet for transferring an embossed shape by pressing a plate having an inverted concavo-convex pattern of not more than 100 μm, the glass transition temperature of the thermoplastic resin is set at Tg ° C.
When the sheet surface temperature immediately before the plate is pressed is Tg
C. or more, the sheet center temperature is (Tg-10) ° C. or less, and the heating is performed so that the heat quantity QkW / m 2 given to the sheet surface when heating and softening the sheet surface and the heating time t seconds satisfy the following relationship. A method for manufacturing a light control sheet, comprising: 10 <Q <1000 and 10 / Q <t <100 / Q
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17579397A JPH1123814A (en) | 1997-07-01 | 1997-07-01 | Optical control sheet and its manufacture |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17579397A JPH1123814A (en) | 1997-07-01 | 1997-07-01 | Optical control sheet and its manufacture |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH1123814A true JPH1123814A (en) | 1999-01-29 |
Family
ID=16002354
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17579397A Pending JPH1123814A (en) | 1997-07-01 | 1997-07-01 | Optical control sheet and its manufacture |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH1123814A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006330723A (en) * | 2005-05-20 | 2006-12-07 | Samsung Electronics Co Ltd | Optical plate, backlight assembly having this, and display device |
JP2007230241A (en) * | 2002-06-18 | 2007-09-13 | Meiki Co Ltd | Press-forming method |
JP2014072489A (en) * | 2012-10-01 | 2014-04-21 | Kuraray Co Ltd | Production method of microstructure, and microstructure |
-
1997
- 1997-07-01 JP JP17579397A patent/JPH1123814A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007230241A (en) * | 2002-06-18 | 2007-09-13 | Meiki Co Ltd | Press-forming method |
JP4679546B2 (en) * | 2002-06-18 | 2011-04-27 | 株式会社名機製作所 | Press forming method |
JP2006330723A (en) * | 2005-05-20 | 2006-12-07 | Samsung Electronics Co Ltd | Optical plate, backlight assembly having this, and display device |
JP2014072489A (en) * | 2012-10-01 | 2014-04-21 | Kuraray Co Ltd | Production method of microstructure, and microstructure |
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