JP2006218648A - Method and apparatus for manufacturing transmission type screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a transmission type screen which reconciles the precise molding of a lens shape and the impartment of a curved shape, which does not change with the elapse of time, to a lens sheet and capable of molding the lens sheet into an arbitrary curved shape, and a manufacturing method of the transmnission type screen. <P>SOLUTION: At least one of a plurality of the lens sheets 3 in the transmission type screen is molded into the curved shape and a plurality of the lens sheets 3 are closely bonded to each other to be used. At least one of the lens sheets 3 is manufactured by extrusion molding using one extruder (mold) 1 and comprises a thermoplastic resin molded into the curved shape at a temperature higher than the softening point of the thermoplastic resin by a roll member R5 (and R5') provided separately from the extruder 1. The roll member R5 (and R5') has a function for curving the lens sheet 3 in the direction crossing the extrusion direction of the lens sheet 3 almost at a right angle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for manufacturing a transmission screen formed by bending at least one of a plurality of lens sheets and bringing them into close contact with each other, and in particular, a transmission screen used for a projection television or the like. The present invention relates to a manufacturing method and a manufacturing apparatus.

  In transmissive screens used for projection televisions and the like, generally, a plurality of optical sheets and lens sheets such as Fresnel lenses, lenticular lenses, prism sheets, front plates and diffusers are closely stacked in the optical axis direction. Is done.

  In a transmissive screen in which a plurality of lens sheets are stacked in the optical axis direction, a transparent thermoplastic resin is often used as a material for the lens sheet. Lenticular lenses and prism sheets are generally manufactured by extruding a thermoplastic resin using a roll having a reverse surface shape.

  However, because the lens sheet made of thermoplastic resin expands and contracts due to changes in the temperature and humidity of the installation environment, the adhesion between the overlapping lens sheets deteriorates, creating a gap between the sheets, and the image is distorted or contoured. There is a problem that the resolution of an image is deteriorated, such as being unclear.

  In order to solve this problem, for example, in Japanese Patent Laid-Open No. 60-61738, a lens sheet arranged on the observer side and a lens sheet arranged on the light source side are both warped toward the light source side, and the lens sheet on the observer side is arranged on the light source side. A transmissive screen has been proposed in which the two are warped larger than the lens sheet and are fixed to each other by fixing them at the periphery. In such a transmission screen, a lens shape is imparted to a transparent resin sheet by a known method, and then a lens molded lens sheet is placed on a curved base and a load is applied from above so that the lens shape does not collapse. It has been performed to form a curved shape by heating for a long time at a temperature below the softening point. Hereinafter, giving a curved shape in this way may be expressed as warping or warping.

Further, in JP-A-5-204048, a thermoplastic resin is extruded and formed by touching a pair of rolls having different roll temperatures so that the inside of the sheet is heated to a softening point or higher. There has been proposed a method of curving a sheet by varying the amount of heat shrinkage between the front and back surfaces of the sheet in the process of causing heat shrinkage upon cooling.
Japanese Patent Laid-Open No. 05-2004048 JP-A-60-611738

  However, as disclosed in JP-A-60-61738, a lens sheet processed and curved at a temperature equal to or lower than the softening point tends to gradually recover and return to the original shape, and the amount of warpage decreases. There was a drawback.

  In addition, the method of Japanese Patent Application Laid-Open No. 5-204048 solves the above-mentioned problem, and it is not necessary to provide a specially shaped step, and a jig for this step, a temperature control facility, etc. are not required. Although it is possible to improve productivity and reduce costs, there are the following problems.

  That is, in extrusion molding, a softened resin is brought into close contact with a molding die, and at least the surface of the resin is solidified, and then the mold shape is transferred by transferring. At this time, considering the heat shrinkage of the resin and the adhesion to the mold, the precise shaping required for optical sheets is achieved unless the resin temperature, molding speed, and pressure with which the roll presses the resin are precisely controlled. Can not do it.

  Here, in the method disclosed in Japanese Patent Laid-Open No. 5-202048, the first roll and the second roll, which are molds, are used to form a lenticular lens shape on the surface of the resin sheet, and then the second roll and the third roll adjacent thereto are used. This is a technique for providing a curved shape by a temperature difference. At this time, the suitability values of the temperatures of the second roll and the third roll for heating the front and back of the sheet should be determined according to conditions such as the thickness of the sheet to be molded, the molding speed, the type of resin, and the like.

  However, the conditions of temperature and molding speed suitable for precision shaping are not necessarily conditions suitable for imparting a curved shape and adjusting the degree thereof. Therefore, there is a problem that it may not be possible to achieve precision shaping and imparting a curved shape at the same time.

  The curved shape required for the optical sheet depends on the optical design, the mounting method to the television set, the appearance design, etc., for example, a shape that is curved only in the width direction or a shape that differs in the degree of curvature vertically and horizontally. In some cases. However, the method disclosed in JP-A-5-204048 can only give a shape curved in the extrusion direction.

  The present invention achieves both the molding of a precise lens shape and the provision of a curved shape whose curved shape does not change over time to the lens sheet, and furthermore, the manufacture of a transmission screen that can easily impart various curved shapes. An object is to provide a method and a manufacturing apparatus.

  In order to solve the above-mentioned problem, a method of the present invention according to claim 1 is a transmissive screen formed by curving at least one lens sheet of a plurality of lens sheets and closely adhering the plurality of lens sheets to each other. In the manufacturing method, the at least one lens sheet is made of a thermoplastic resin, manufactured by extrusion molding using a mold, and at a temperature equal to or higher than the softening point by a roll member provided separately from the mold. The roll member has a function of bending the lens sheet in a direction substantially orthogonal to the extrusion direction, and the lens sheet passes through the roll member and is formed into the curve shape. Features.

  According to a second aspect of the present invention, there is provided the transmissive screen manufacturing method according to the first aspect, wherein the lens sheet is pressed by the roll member from both sides of the lens sheet.

  Furthermore, the apparatus of the present invention according to claim 3 is an apparatus for manufacturing a transmissive screen formed by bending at least one lens sheet of a plurality of lens sheets and bringing the plurality of lens sheets into close contact with each other. A molding die for extruding a lens sheet made of at least one thermoplastic resin is provided. Separately from the molding die, the lens sheet is substantially at the temperature equal to or higher than the softening point of the thermoplastic resin. A roll member that is curved in an orthogonal direction is provided, and the lens sheet passes through the roll member and is molded into the curved shape.

  Furthermore, the present invention described in claim 4 provides the transmission screen manufacturing apparatus according to claim 3, wherein the roll member is a pair of roll members that press-contact the lens sheet from both surfaces of the lens sheet.

  According to the first aspect of the present invention, in the transmissive screen formed by curving at least one of the plurality of lens sheets and bringing the sheets into close contact with each other, the at least one lens sheet is a thermal screen. The lens sheet is formed by extruding a plastic resin, and the lens sheet is formed into a curved shape at a temperature equal to or higher than the softening point of the thermoplastic resin using a roll member provided separately from the mold.

  In this case, the roll member is formed by curving the lens sheet in a direction substantially orthogonal to the extrusion direction of the plurality of lens sheets. As a result, a precise lens shape in which the plurality of lens sheets are satisfactorily adhered is formed, and an arbitrary curved shape can be imparted in the lateral direction of the sheet.

  In particular, according to the second aspect of the present invention, since the roll member is provided so as to be pressed from both sides of the plurality of lens sheets, the plurality of lens sheets are closely contacted from both sides and formed into a desired curved shape. To do.

  According to a third aspect of the present invention, there is provided a molding die for extruding a lens sheet made of at least one thermoplastic resin, and the lens sheet uses a roll member provided separately from the molding die. The lens sheet is molded in a direction substantially perpendicular to the extrusion direction of the plurality of lens sheets at a temperature equal to or higher than the softening point of the thermoplastic resin. Accordingly, the plurality of lens sheets adhere well and are formed into an arbitrary curved shape in the sheet lateral direction.

  According to the second aspect of the present invention, since the roll member presses the plurality of lens sheets from both sides thereof, the adhesion of the plurality of lens sheets is further improved.

  According to the first and third aspects of the present invention, since the lens sheet is formed in a curved shape at a temperature equal to or higher than the softening point, the warp amount does not decrease even after a long time has passed, and a plurality of lens sheets can be stabilized. Thus, it is possible to obtain a transmissive screen in close contact with each other. In particular, since an arbitrary curved shape can be formed in the width direction of the sheet, a transmissive screen that simultaneously forms a precise lens shape and imparts a curved shape that does not change with time to the lens sheet. The production method and the production apparatus can be obtained.

  Further, in the present invention according to claim 2 or 4, since the plurality of lens sheets are formed in close contact with the roll member from both sides thereof, it can be more precisely and reliably formed into an arbitrary curved shape. A method and apparatus for manufacturing a transmission screen can be provided.

  The present invention provides a method for producing a transmission screen that can form an arbitrary curved shape easily by simultaneously forming the precise lens shape and imparting a curved shape whose curved shape does not change over time to a lens sheet. In order to provide a manufacturing apparatus, at least one lens sheet of the plurality of lens sheets is curved, and the plurality of lens sheets are formed in close contact with each other, and the at least one lens sheet is made of a thermoplastic resin. , Manufactured by extrusion using a mold, and formed into a curved shape at a temperature above the softening point by a roll member provided separately from the mold, and the roll member extrudes the lens sheet in the extrusion direction. And the lens sheet passes through the roll member and is formed into the curved shape. And summarized in that from both sides of Nzushito were to be pressed by the roller member.

  Next, an embodiment of the present invention will be described with reference to FIGS. The lens sheet according to the transmissive screen of the present invention is made of a thermoplastic resin formed into a curved shape by a roll member at a temperature equal to or higher than the softening point. As a method for measuring the softening point of the resin, the Vicat test (ASTM D 1525 or JIS K 6742), heating strain temperature test (ASTMD 648-45T), etc., and the softening point may differ slightly depending on the measurement method, but the present invention can be applied to any measurement method. Is.

  As the thermoplastic resin used in the present invention, for example, a transparent thermoplastic resin such as polymethyl methacrylate, polystyrene, and polycarbonate can be used. These copolymers, modified materials such as rubber modifications, and mixtures thereof can also be used.

  In the present invention, the roll member used to warp the plurality of lens sheets 3 from both sides thereof is provided with a warp roll Ra and a roll Rb as shown in FIG. Can be granted. FIG. 3 is a schematic view of the lens sheet 3 viewed from the downstream side in the pushing direction (conveying direction S in FIG. 2). The roll Ra and the roll Rb are provided so as to be pressed from both the upper and lower surfaces of the lens sheet 3. The roll Ra and the roll Rb can give a convex warpage shape upward in the sheet width direction. Here, the roll Ra and the roll Rb are heated so that the temperature of the lens sheet 3 is equal to or higher than the softening point. Of course, the warp directions of the roll Ra and the roll Rb may be upside down with respect to the warp direction of FIG. 3, and a warp shape convex downward in the sheet width direction can be provided.

  Further, as shown in FIG. 3, when a convex warp shape is imparted to the roll Ra side, the temperature of the roll Rb is preferably higher than the temperature of the roll Ra. This is because the amount of heat shrinkage between the front and back surfaces of the lens sheet 3 can be varied to impart a curve in the extrusion direction.

  Further, by adjusting the amount of warpage due to the temperature difference and the amount of warpage due to the curvature of the roll Ra and the roll Rb, the extrusion direction and the width direction can be warped in different degrees or in different directions.

  Further, when the resin is in contact with the roll Ra and the roll Rb is extremely short, and the resin temperature cannot be accurately adjusted within that time, it is preferable to provide a plurality of rolls Ra and rolls Rb in the extrusion flow direction. . Here, when a plurality of rolls Ra and rolls Rb are provided, it is more preferable to lower the temperatures of the rolls Ra and Rb as it goes downstream in the extrusion direction. It is estimated that it is possible to suppress the occurrence of internal distortion by gradually lowering the temperature of the extruded lens sheet 3.

  Further, either one of the roll Ra and the roll Rb can be omitted. Even when the roll Ra is omitted, the lens sheet 3 can be bent by its own weight, and the warped shape of the roll Rb can be imparted. When the roll Rb is omitted, a warp shape of the roll Ra can be imparted by applying tension in the sheet pushing direction and the lens sheet 3 being in close contact with the roll Ra.

  The roll Ra and / or the roll Rb is particularly preferably an expander roll 2 as shown in FIG. This is because the expander roll 2 can adjust the amount of deflection, so that the amount of warpage can be easily adjusted without replacing rolls having different warping directions and curvatures.

Using a polymethylmethacrylate / styrene copolymer, a 2 mm-thick lens sheet 3 is produced by an extruder 1 as shown in FIG. 1, and the roll Rb of FIG. A roll R5 having an upward convex warp was used and arranged to warp in the sheet width direction.
Extrusion resin temperature: 223 ° C
Extrusion speed: 3.4 m / min Table 1 shows the temperatures of the rolls R1 to R4 and R5.

ロールR１〜R４の温度は温度調整装置により表示の温度に調整してある。ロールR５には温度調整装置がなく、ロールR５の位置での樹脂の温度を測定して表示している。

The temperatures of the rolls R1 to R4 are adjusted to the display temperature by a temperature adjusting device. The roll R5 has no temperature adjusting device, and the temperature of the resin at the position of the roll R5 is measured and displayed.

The sheet width is the same as in Example 1 except that a roll R5 having a concave warp such as the roll Ra in FIG. 3 is used below the lens sheet 3 and the temperature adjustment is as shown in the table below. The lens sheet 3 was manufactured by curling the direction.
Extrusion resin temperature: 230 ° C
Extrusion speed: 3.4 m / min Table 2 shows the temperatures of the rolls R1 to R5.

ロールR１〜R４の温度は温度調整装置により表示の温度に調整してある。ロールR５には温度調整装置がなく、ロールR５の位置での樹脂の温度を測定して、表示している。

The temperatures of the rolls R1 to R4 are adjusted to the display temperature by a temperature adjusting device. The roll R5 has no temperature adjusting device, and the temperature of the resin at the position of the roll R5 is measured and displayed.

The sheet width direction warpage is performed in the same manner as in Example 2 except that the expander roll 2 having an upward convex warpage as shown in FIG. Then, the lens sheet 3 was manufactured.
Extrusion resin temperature: 230 ° C
Extrusion speed: 3.4 m / min Table 3 shows the temperatures of the rolls R1 to R4.

ロールR１〜R４の温度は温度調整装置により表示の温度に調整してある。エキスパンダーロール２には温度調整装置がなく、エキスパンダーロール２の位置での樹脂の温度を測定して、表示している。

The temperatures of the rolls R1 to R4 are adjusted to the display temperature by a temperature adjusting device. The expander roll 2 has no temperature adjusting device, and the temperature of the resin at the position of the expander roll 2 is measured and displayed.

  The lens sheets 3 of Examples 1 to 3 immediately after manufacture were cut into a size of 1 m × 1 m, and the amount of warpage (maximum warp depth) in a suspended state was measured. Here, a positive numerical value indicates a convex shape toward the upper surface side of the lens sheet 3 during extrusion, and a negative numerical value indicates a concave shape on the lower surface side. Further, Table 4 shows the change over time in the amount of warping when the lens sheet 3 obtained in Examples 1 to 3 is left in a normal room temperature and humidity (approximately 25 ° C., 50% RH) for one week. . In all cases, there were no irregular swells.

この表から明らかなように、本発明による透過型スクリーンはその反り量が安定化し、減少することがない。従って、長期間、他のレンズシートを組み合わせて使用しても、密着不良が生じて画質が劣化するおそれがない。ここで製造直後の反り量が小さかった理由としては、押出し製造中は長さ方向に張力が掛かっており、反りを小さくする力がレンズシート３に掛かったため、製造直後は反りが発現しなかった、と推定される。

As is apparent from this table, the amount of warpage of the transmissive screen according to the present invention is stabilized and does not decrease. Therefore, even if other lens sheets are used in combination for a long period of time, there is no possibility that the image quality deteriorates due to poor adhesion. Here, the reason for the small amount of warping immediately after production was that tension was applied in the length direction during extrusion production, and the lens sheet 3 was subjected to a force to reduce warpage, so that warpage did not appear immediately after production. ,It is estimated to be.

  As described above, in the transmissive screen formed and used by curving at least one lens sheet 3 of the plurality of lens sheets 3 and in close contact with each other, the at least one lens sheet 3 includes: A roll member made of a thermoplastic resin produced by extrusion molding and formed into a curved shape at a temperature above the softening point by a roll member R5 (and R5 ') provided separately from the extruder (molding die) 1. R5 (and R5 ′) has a function of bending the lens sheet 3 in a direction substantially orthogonal to the extrusion direction.

  As a result, the amount of warp does not decrease even after a long time, and a plurality of lens sheets 3 can be stably adhered to each other to form a precise lens shape, and an arbitrary curved shape is imparted in the sheet width direction. Thus, a manufacturing method and a manufacturing apparatus for the transmissive screen were obtained.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

It is a schematic diagram which shows the lens sheet manufacturing apparatus provided with the extruder which concerns on this invention. It is a schematic diagram which shows the structural example which provided the warp roll by this invention in the extruder of FIG. It is the schematic which looked at the lens sheet which concerns on this invention from the extrusion direction downstream. It is the schematic which looked at the expander roll which concerns on this invention from the extrusion direction downstream.

Explanation of symbols

1 Extruder (mold)
2 Expander roll 3 Lens sheet
R1 ~ R4 roll
R5, R5 'roll member (curled roll member)
Ra, Rb Warping roll

Claims (4)

  In the method of manufacturing a transmissive screen formed by curving at least one lens sheet of a plurality of lens sheets and bringing the plurality of lens sheets into close contact with each other, the at least one lens sheet is made of a thermoplastic resin. It is manufactured by extrusion molding using a mold, and is formed into a curved shape at a temperature equal to or higher than the softening point by a roll member provided separately from the mold, and the roll member has the lens sheet in the extrusion direction. A method of manufacturing a transmission type screen, which has a function of bending in a direction substantially orthogonal, and the lens sheet passes through the roll member and is formed into the curved shape.   2. The method of manufacturing a transmission screen according to claim 1, wherein the lens sheet is pressed by the roll member from both sides of the lens sheet.   In a transmissive screen manufacturing apparatus formed by bending at least one lens sheet of a plurality of lens sheets and bringing the plurality of lens sheets into close contact with each other, the lens sheet made of the at least one thermoplastic resin is extruded. In addition to the mold, there is provided a roll member that forms the lens sheet in a curved shape in a direction substantially perpendicular to the extrusion direction at a temperature equal to or higher than the softening point of the thermoplastic resin. An apparatus for manufacturing a transmission screen, wherein the lens sheet passes through the roll member and is formed into the curved shape. 4. The transmission type screen manufacturing apparatus according to claim 3, wherein the roll member is a pair of roll members that press-contact the lens sheet from both surfaces of the lens sheet.

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