JPH0437833A - Production of projection screen - Google Patents

Abstract

PURPOSE:To eliminate the unequal interspindle spacing at the time of spinning and to obtain the uniform screen by using a nozzle disposed annularly with many discharge ports for light transparent strands. CONSTITUTION:The discharge ports 3A1 for the light transparent strands 10 are annularly arranged in the nozzle 3 and the same number of the small- diameter discharge ports 3A2 for external light absorption layers 12 are disposed in the same manner between these ports. A polymethyl methacrylate melt is supplied to the discharge ports 3A1 and a polymethyl methacrylate melt contg. a carbon black is supplied to the discharge ports 3A2 to execute spinning. While the melts are taken off, the melts are fused and divided to a sheet shape. The sheets are taken off from reels 8 and are passed in far IR heaters 21, 22; thereafter, the sheets are fused to each other while the sheets are brought into proximity to each other by a bending guide 23.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a transmissive or reflective projection screen #4 used as a screen for a projector television, a microfilm reader, etc. be.

BACKGROUND OF THE INVENTION Projection screens are widely used for display purposes such as film advertisements, projected television images, microfilm images, etc. This type of projection screen is usually equipped with a predetermined lens on the entrance or exit surface so that it is bright when viewed from the wA viewing side and widens the viewing angle. For example, the use of double-sided lenticular lenses or ply eyes is disclosed in Japanese Patent Application Laid-Open No. 58-5943.
No. 6, Utility Model Publication No. 52-4932, JP-A-57-8125
No. 4, JP-A-57-81255 and JP-A-58-1
It is disclosed in publications such as No. 08525.

However, in order to obtain the desired characteristics of this type of screen, it is essential to accurately control the mutual positional relationship of the lenticular lenses or fly's eyes on both sides. For example, for a lenticular lens with a pitch of about one square, positional accuracy of within ±24, that is, about ±20μ, is required for both the axis deviation and plate thickness variation on both sides. If the error is not kept within this range, problems such as deterioration of color balance, narrowing of the viewing range, and occurrence of color unevenness within the screen will occur.

Most of the double-sided lenticular lenses that are currently in practical use are molded products of methacrylic resin, and the molding methods include: ■ Roll forming method using an extruded plate, ■ Casting method using cell casting, ■ EE! using hot press! ! Technologies such as molding methods are applied, and in both cases a method is adopted in which a metal master mold is directly or indirectly transferred to a resin plate.

In order to accurately make a double-sided lenticule lens, the dimensional accuracy of the purlins themselves on both sides must be high, the mold temperature during B1 molding must be uniform, and the molding shrinkage of the resin must be reduced. Accurate alignment and no wobbling are required; for example, a 1 meter square screen pitch of 11! If a double-sided lenticular lens with a thickness of 1 inch is formed, and the allowable accuracy of the misalignment and plate thickness is within ±2, the positional accuracy of the double-sided lenticular lenses will be as shown in A and B above.

O Including all error factors, ±2 both in the lateral direction and in the thickness direction
This means that it must be kept within 0μ.

However, when we looked at the coefficient of linear expansion of metals, we found that steel
:tlxlo-s 1/'C aluminum: 1
．． 7 x 10” p brass: 1
．． 8 X I D-5tt, per length 1m,
If the temperature changes by 1°C, it is calculated that 11μ of steel, 17μ of aluminum, and 18μ of brass will expand and contract, so it is extremely important for mold machining accuracy (including factory temperature control accuracy), molding temperature control, and positioning of double-sided molds. This will require advanced equipment and technology.

In recent years, there has been a strong trend toward higher definition in large TVs, and the lenticular lenses of screens are also required to have a finer pitch.However, as mentioned above, at the current industrial technology level, for example, lenticular lenses of 1 meter square are made of plastic. It is not easy to make the positional deviation of the front and back surfaces of the lenticular lens plate much more accurate than the above value.

For this reason, if a transparent cylindrical body in which the lenticular lens units of the entrance surface and the exit surface are integrated is used as a lens unit,
It is considered that it is easy to ensure the mutual positional relationship between at least the lenticular lenses on both sides. For example, JP-A-47-
No. 28925, Utility Model No. 59-121647, Utility Model No. 5
Specific proposals have been made in No. 9-121648 and Japanese Utility Model Application Publication No. 59-123850.

(Problem to be Solved by the Invention) However, as soon as the screen of the above proposal is prototyped, it becomes clear that in any case, gaps between the cylindrical lenses always occur, and the straight line leaks from there. When the light beam is used as a projection screen, there are so many problems (jeeses, hot bands, etc.) that it is practically impossible to provide a screen with good characteristics.

This is because the accuracy of the diameter of currently available transparent fiber cylinders varies by at least several winters on the mainland, and simply arranging them will inevitably result in gaps. Even if the cylindrical bodies are arranged side by side while applying force to press them against each other, if there is no means to securely hold them together, gaps will still form as a result.

Furthermore, in JP-A No. 47-28925, there is a description of arranging elongated cylindrical lenses in a layered manner, coating the layers with a dark color, and providing non-coated areas to scatter and emit light. Considering that this type of product has not been put into practical use in the industry, the specific manufacturing method has not been established, and it is thought that it was impossible to realize it because of the light shining through the gap. It will be done.

For this reason, the present inventors first proposed a screen with excellent performance by arranging translucent strands in parallel without gaps and integrating them into a sheet, and arranging the translucent strands with high precision, and a method for manufacturing the same. The aim is to obtain uniform translucent strands and, by extension, a uniform screen.

(Means for Solving the Problems) That is, the present invention has been made to solve the above-mentioned problems. A method for obtaining a screen body by fusing the surfaces to form a sheet and using one or more sheets, characterized by using a nozzle in which a large number of discharge ports for the translucent strands are arranged in an annular manner. The gist of this paper is a method of manufacturing a projection screen.

The present invention will be explained below with reference to the drawings.

1 to 3 show examples of projection screens obtained by the present invention, in which (10) is a plastic translucent strand.

Of these, the example in Figure 1 is an example with a circular cross-sectional shape, Figure 2 is an example of a non-circular cross-sectional shape with an oval shape, and Figure 3 is an example in which an external light absorption layer is formed between the translucent strands. This is an example.

The outer surfaces of these adjacent translucent strands (10) are fused (11) and integrated as shown in FIG. is configured. Note that (12) in the figure is an external light absorption layer. The projection screen of the present invention preferably consists of a single sheet integrated as described above, but it is not necessarily limited to the case where it is composed of a single sheet, and two or several V-) sheets are integrated. They may be configured by being connected. Even when a plurality of sheets are connected in this way, the pitch accuracy is significantly improved compared to when simply arranging each strand one by one.

The translucent strand (10) of the present invention is made of plastics with good light transmittance, such as thermoplastic polymers such as acrylic polymers, polycarbonate polymers, and polyacrylates, and crosslinked cured materials such as crosslinked silicone polymers, crosslinked acrylate polymers, and ionic crosslinked polymers. Manufactured by mold polymer etc. At this time, the translucent strand (1o
) varies depending on the size, use, and purpose of the screen, but is generally selected to be approximately α1 to 1.5−, which sufficiently contributes to making the screen fine pitch. The outer surface of the light-transmitting strand (10) may be smooth or may have fine irregularities.

Furthermore, this translucent strand (10) may be colored with an appropriate coloring agent, or may be mixed with a light diffusing agent.

The projection screen of the present invention is manufactured by a melt spinning method, and the manufacturing method will be explained below with reference to FIGS. 5 to 8. That is, in the figure (1) is the extruder,
(2) is a die equipped with a nozzle (3), and the molten plastic is discharged from the discharge port. In such a manufacturing method, the present invention provides a discharge port (3A) as shown in FIG.
) are arranged in an annular manner using a nozzle (3). When such a nozzle (3) is used, the nozzle pack is generally heated externally, so each discharge port (
3A) The temperature distribution becomes uniform, and as a result, there is no unevenness between the spindles of the translucent strand (1o) during melt spinning, and it is possible to spin a translucent strand (10) with a uniform shape and no kinks. can. At this time, a metering pump may be installed to ensure stability of the discharge amount.

The ejected translucent strands (10) are fused together along the inner wall of an annular guide (4) provided directly below the nozzle, and divided from annular to linear by a bell-shaped guide (5). , and then continue with a rod-shaped straight guide (6
) to make a straight line, take it off with a nip roller (7), wind it up on a reel (8), and make it into a sheet.

In the above embodiment, the translucent strands (10) are melt-spun into a sheet shape, but the inlet sides are separate and the dies are used to join at a position immediately before or after the discharge port, thereby connecting the translucent strands (10). It is also possible to manufacture it by integrating it into a sheet shape.

Furthermore, the present invention is applicable not only to the production of translucent strands using a single polymer, but also to the production of strands with a core-sheath dual structure using different polymers, such as optical fibers. It is also possible to simultaneously form the portions that will become the two parts using a conjugate spinning technique. Note that when manufacturing the transmission-type screen thinner of the present invention, it is desirable to use a single sheet over the entire width of the screen, but if there are restrictions due to equipment, a sheet of a predetermined width that is a unit is manufactured, These may be connected using adhesive or adhesive tape.

(Example) A specific example of the present invention will be described below. A projection screen as shown in FIG. 5 was manufactured using the apparatus shown in FIGS. 4 to 10.

As shown in Fig. 9, the nozzle used at this time has a 200-hole annular array of ejection ports (3A+) for translucent strands, and an equal number of small-diameter ejection ports (3An) for the external light absorbing layer between these holes. I used something.

Of these, the polymethyl methacrylate melt is supplied to the discharge port (3A+) for α32/min per hole, and the discharge port (37h) that reaches the external light absorbing layer is supplied with 5
A polymethyl methacrylate melt containing carbon black of No. 4 was fed at a rate of F)Q of 05 t/min per hole and spun at a die temperature of 250°C.

While taking this at a speed of 2.4 m/min, it was fused and divided using an annular guide and a bell-shaped guide, and then arranged in a straight line using a linear guide to form a sheet. Note that water at 20° C. was passed through all of the guides of the above B3 types to cool them.

The sheet thus obtained was a sheet consisting of 200 translucent strands having a diameter of α4 m and arranged uniformly in a straight line, with an external light absorbing layer formed between the strands.

Next, this sheet was made wide using the apparatus shown in Figure 10 to produce a transmission type projection screen. That is, 20 sheets are taken from a reel (8) set on a creel stand using a first nip roller (20), passed through a first far-infrared heater (21) to remove curls,
Next, it is heated through a second far-infrared heater (22),
Immediately, the sheets are brought close to each other and fused using the curved par-shaped bending guide (23), and then the second nip roller (24)
The cutter (2 m/min.
5), it was cut into a length of 1 m.

When the obtained projection screen was attached to a color projection television and observed, a picture screen was obtained that was bright and clear not only from the front but also when viewed from an oblique direction, and had good color tone and contrast.

(Effects of the Invention) Since the present invention has the configuration as described in detail above, it has the advantage of being able to efficiently manufacture a projection screen with high precision and excellent performance that allows sufficiently fine pitch formation. .

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing a part of a projection screen manufactured according to the present invention, FIG. 5 is a schematic plan view of an apparatus for carrying out the method of the present invention, and FIG. A bottom view of the nozzle used, FIGS. 7(A) and (B) are a plan view and a sectional view of the annular guide, FIGS. 8(A) and (B) are a plan view and a sectional view of the bell-shaped guide, and FIG. 9 is a bottom view of the nozzle used. 10 is a bottom view showing a part of the nozzle used in the example, and FIG. 10 is a side view schematically showing the same apparatus for joining sheets used in the example. (10)...Translucent strand (1)...Extruder (2)...Dice (5)...Nozzle Figure 5 Figure 6

Claims (1)

[Claims] 1. A large number of transparent plastic strands are melt-spun, and the outer surfaces of the transparent strands are fused together to form a sheet, and one or more of these sheets are used to form a sheet. 1. A method for producing a projection screen, the method comprising using a nozzle having a plurality of ejection ports arranged in an annular manner for the translucent strand. 2. The method of manufacturing a projection screen according to claim 1, wherein a nozzle having a non-circular discharge opening is used. 3. The method of manufacturing a projection screen according to claim 1 or 2, characterized in that a nozzle is used in conjunction with a small-diameter discharge port so that the external light absorbing layer is located between the light-transmitting strands.