JP2758281B2 - Spinneret for producing projection screen and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a transmission type or reflection type projection screen used as a screen of a projection television or a microfilm reader, and a spinneret used for the production. More specifically, the present invention relates to a method for producing a transmission type or reflection type projection screen having lenticulars on both sides, and a spinneret used for the production.

In this specification, the term "spinneret" includes a so-called die, and the term "orifice shoulder" refers to a cross-sectional view of an adjacent orifice of a strand. When viewed with the side corresponding to the light emitting side facing up, it means a portion corresponding to both shoulders of these orifices. In this portion, the light emitting side of the strand and both peripheral portions excluding the light emitting portion are included. The molten polymer for the light-shielding auxiliary portion formed into an eight-shape is injected.

[0003]

2. Description of the Related Art Projection screens are widely used for display purposes such as projection televisions and microfilm readers. Such a projection screen is usually provided with a predetermined lens on an entrance surface or an exit surface or both an entrance surface and an exit surface so as to be bright when viewed from the observation side and to enlarge the viewing angle. It is.

Providing a lenticular lens or a fly-eye lens on both surfaces is disclosed, for example, in Japanese Patent Laid-Open No. 58-5 / 58.
No. 9436, Japanese Utility Model Publication No. 52-4932, Japanese Unexamined Patent Publication No. 57-8
No. 1254, JP-A-57-81255 and JP-A-58
-108523 and the like.

By the way, as a method of manufacturing a double-sided lenticular lens or the like, an extrusion molding method, a casting method by cell casting, a heating press method, and the like are currently in practical use. However, in order to provide a projection screen having lenticular lenses on both sides with desired optical characteristics, it is essential to precisely control the positional relationship between the lenticular lenses or fly-eye lenses on both sides.

In order to accurately manufacture a double-sided lenticular lens, etc., (1) the dimensional accuracy of the matrix on both sides is high, (2) the mold temperature during molding is uniform, and the molding shrinkage of the resin is uniform. (3) It is required that the alignment of both sides is accurate and there is no backlash.

For example, at a lens pitch of 1 mm and a thickness of 1 mm,
When making a 1 m square double-sided lenticular lens, if the tolerances of lateral displacement and plate thickness are within ± 2%, the mutual accuracy of the double-sided lenticular lens is 1 (1),
The total error factors (2) and (3) must be kept within ± 20 μm both in the horizontal direction and in the thickness direction.

[0008] In recent years, the trend toward higher precision (fineness) of large-sized televisions has been strengthened, and lenticular lenses for screens have also been required to have finer pitches. It is not easy to suppress the positional displacement of the front and back surfaces of the lenticular lens plate to be less than the above value and to make the lenticular lens fine pitch on the screen. For this reason,
It is considered that when a cylindrical body in which the lenticular lens units on the entrance surface and the exit surface are integrated is used for the lens unit, at least the positional relationship between the lenticular lenses on both surfaces is easily ensured. Such an idea is described, for example, in
Nos. -28925, 59-121647, 59-121645 and 59-123850. However, when a screen is prototyped in accordance with the above-described disclosed technology, it is immediately understood that in any case, a gap always occurs between the cylindrical lenses, and straight rays leaking therefrom are, for example, see-through, A hot band or the like is generated, which is extremely inconvenient for the projection screen, and it is practically impossible to produce a screen having good optical characteristics.

[0009] This is because the diameter of currently available transparent fiber-shaped cylindrical bodies varies at least about ± several percent, so that simply arranging these cylindrical bodies inevitably results in a gap between them. This is because there is a gap in the space. Even if the cylindrical bodies are arranged while applying a pressing force to these cylindrical bodies, a gap is still formed as a result unless there is a means for firmly fixing them.

[0010] For this reason, the present inventors have tried to eliminate the adverse effect of inter-weight unevenness in melt-extrusion of the strands and obtain a uniform screen composed of the translucent strands. A method for manufacturing a projection screen in which the outer surfaces are joined (fused) to form a sheet, and a method for manufacturing a projection screen in which a large number of plastic-based translucent strands are melt-extruded into a sheet from the beginning. Furthermore, in the method of manufacturing a projection screen as described above, a strand composed of a light-transmitting main part and an auxiliary part having optical characteristics different from the main part by utilizing a so-called composite spinning technique. And a method of manufacturing a screen by extrusion.

[0011]

A sheet is formed by joining the outer surfaces of a number of plastic-based light-transmitting strands,
In the method of manufacturing a projection screen, in order to improve the optical characteristics of the screen, particularly the contrast when the screen is attached to a color projection television for observation, light is shielded at valleys or grooves formed by joining adjacent strands. It is necessary to provide a part. It is important that the light shielding portions are uniformly arranged on both sides of the light emitting portion on the light emitting side of the strand.

In order to dispose the light-shielding portion in the valley or groove as described above, the following method is generally adopted. (1) First, apply masking to the top of the strand, then apply black paint to the entire light emission side surface, and finally peel off the mask. (2) First, apply black photoresist to the entire light emission side surface. Next, the light emission side surface is exposed so that light shines only on the top portion of the strand, and only the valley (or groove) portion that has not been irradiated with light is cured, and finally, the uncured photoresist on the strand top portion is removed. (3) Apply black paint only to valleys (or grooves) using a squeegee. However, all of these methods involve complicated steps, and it is extremely difficult to accurately arrange the light shielding portions on both sides of the light emitting portion and along the length direction of the strand.

Therefore, there is a strong need to more effectively produce projection screens having sufficiently satisfactory optical properties. The present invention has been intensively developed to meet such demands.

[0014]

According to a first aspect of the present invention, there is provided: (a) a light-transmitting main portion which is opened on a discharge surface of a spinneret.
Orifices for extruding the molten polymer for use in the light-shielding auxiliary part;
If, (c) a lower end portion of the flow path for the light-shielding auxiliary portion and the transmissive
Orifice for connecting with the orifice for the main body
And (d) the connecting orifice is for an adjacent light-transmitting main body.
To the middle position of the orifice
Ri, (e) Further, the connecting orifice spinneret discharge surface
Slightly before the orifice for the translucent body
The light-transmitting main body is made of a transparent polymer
Injected along the flow of the molten polymer for the part
The spinneret has an opening so that it can be
It is about.

According to a second aspect of the present invention, there is provided: (a) a light-transmitting main portion which is open to a discharge surface of a spinneret.
A large number of orifices for extruding the molten polymer for use in (b) a position slightly in front of the spinneret discharge surface;
Extends parallel and perpendicular to the orifice for the translucent body
The molten polymer for the light-shielding auxiliary part provided
And (c) a lower end portion of the flow path for the light-shielding auxiliary portion and the light transmission.
Orifice for connecting with the orifice for the main body
When have, (d) the connecting orifice is extended horizontally, moreover (e), the connecting orifice spinneret discharge surface
Slightly before the orifice for the translucent body
The light-transmitting polymer for the light-shielding auxiliary part is
Injected in the direction across the body polymer melt flow
There spinneret characterized that you have to urchin open.

[0016] Further, the third invention provides a method for preparing a thermoplastic polymer in a large amount.
Dispensed in a molten state from a spinneret with a number of orifices
A large number of plastic-based translucent strands or
Form a sheet consisting of strands and project the screen
A method for producing, using any one of the above spinneret
Use the above-mentioned orifice to make the light-transmitting main part and light-shielding
The molten polymer that forms each of the parts is
Is the light exit side of the strand and both sides except the light exit part
Are discharged simultaneously so that the cross section is
A method for manufacturing a projection screen characterized by
A shall, furthermore, as to one embodiment thereof, the multi
Uses the above spinneret with a number of orifices arranged in a ring
And place the formed annular sheet below or above the spinneret.
After passing through the arranged ring guide, it is deformed into a flat shape
Preferably, the annular sheet is first attached to the first ring guy.
Through the first ring guide and then a smaller diameter than the first ring guide.
After passing through the second ring guide having
Includes how to shape.

[0017]

The present invention will now be described in further detail with reference to the drawings. 1 and 2 show a spinneret of the present invention.
FIG. 1 schematically shows an example of a projection screen manufactured by a manufacturing method of the present invention using gold, wherein 1 is a plastic-based translucent strand, and 2 is the plastic-based translucent strand 1. The light-transmitting main portion 3 constituting the light-transmitting portion 3 is a light-shielding auxiliary portion forming a light-shielding portion of the plastic light-transmitting strand 1.

[0018] The projection screen is what is more preferably made of a single sheet may be constructed by connecting two or more sheets.

The light-transmitting main part 2 constituting the light-transmitting part of the light-transmitting strand 1 is made of a thermoplastic polymer having good light-transmitting properties, for example, acrylic polymer, polycarbonate, polystyrene, cross-linked silicon polymer, cross-linked acrylate. It is formed of a thermoplastic polymer such as a polymer and an ion-crosslinkable polymer. The light-transmitting main portion 2 may be colored with an appropriate coloring agent, or may be mixed with a light diffusing agent. It is also possible to add a second component having a specific wavelength selective absorption ability.

The light-shielding auxiliary part 3 constituting the light-shielding part of the light-transmitting strand 1 is made of the same polymer as the polymer used for the light-transmitting main part 2 and an external light-absorbing substance such as carbon black. It is preferred to use the added mixture.

The thickness of the translucent strand 1 varies depending on the size, application and purpose of the screen, but is generally about 0.1.
A diameter of about 1.5 mm is selected, and if it is in this range, it contributes sufficiently to the fine pitch of the lenticular lens on the screen.

The above-mentioned projection screen is manufactured in principle by a technique of melt extrusion. Hereinafter, the method for manufacturing the projection screen according to the present invention and the spinneret used for the manufacture will be described in more detail with reference to FIGS.

FIG. 3 schematically shows an apparatus for manufacturing the above-mentioned projection screen. In FIG.
13 is a spinneret holder having a spinneret 12, 14 is a first ring guide, 15 is a second ring guide, 16 is a trowel-shaped guide,
17 is a straight guide, 18 is a nip roller, and 19 is a sheet winding machine. In the illustrated example, the molten thermoplastic polymer is discharged from the downward orifice (discharge port), but the extrusion direction may be upward or obliquely upward.
FIG. 4 schematically shows a longitudinal section and a discharge surface of an example of a spinneret according to the first invention. FIG. 5 schematically shows a longitudinal section and a discharge surface of a spinneret example according to the second invention. FIG. 6 is a sectional view of the first ring guide, and FIG. 7 is a sectional view of the second ring guide. FIG. 8 schematically shows a cross section of the trowel guide.

In the present invention, when the thermoplastic polymer is melt-extruded, the spinneret 12 as illustrated in FIGS.
Use In these figures, (a) schematically shows a longitudinal section of the spinneret 12, and (b) schematically shows a plane section of the spinneret 12 incorporating a flow path of the light-shielding auxiliary material. In these figures, reference numeral 12-1 denotes a main body orifice for extruding a molten polymer for the light-transmitting main body 2, and 12-1.
-2 is a flow path of the molten polymer for the light-shielding auxiliary part 3, and 12-3
Is a connection orifice for connecting the auxiliary flow path 12-2 and the orifice 12-1 for the light-transmitting main portion.

In the spinneret 12 shown in FIG. 4, the vertically extending main body orifice 12-1 for extruding the molten polymer for the light-transmitting main body 2 is one. At a distance such that the strands extruded from the orifice 12-1 are joined to the strands extruded from the adjacent main part orifice 12-1 by the Belas effect (elastic recovery of the molten polymer), or at the adjacent orifices 12- 1,12-1
Many are open at the discharge surface of the spinneret 12, with an interval that the outer peripheral portion of the
Further, a flow path 12-2 of the molten polymer for the light-shielding auxiliary section 3 is provided, and this flow path 12-2 is provided with an orifice 12-1 for the light-transmitting main section.
And the connection orifice 12-3. The connecting orifice 12-3 is adjacent to the main body orifice 12-1,12-1
The orifice 12-3 is extended at a position just in the middle and inclined downward.
At a position slightly in front of the spinneret discharge surface of 12-1, the molten polymer for the light-shielding auxiliary portion 3 is provided on the shoulder portion of the main portion orifice 12-1, 12-1 and preferably only on the shoulder portion. Is injected into the flow of the molten polymer for the light-transmitting main portion 2 from obliquely above so as to flow along the flow.

In the spinneret 12 shown in FIG. 5, a vertically extending main body orifice 12-1 for extruding a molten polymer for the light transmitting main body 2 is extruded from one orifice 12-1. At intervals such that the strands to be joined to each other by the bales effect and the strands extruded from the adjacent main body orifice 12-1, or the adjacent orifices 12-1,1
A large number of openings are formed on the discharge surface of the spinneret 12 at intervals such that the outer peripheral portions of the 2-1 slightly contact each other and in a fixed pattern. 12-2
The main body orifice 12-1 is provided to extend vertically in parallel with the main body orifice 12-1 to a position slightly in front of the spinneret discharge surface of the main body orifice 12-1. Is located slightly in front of the spinneret discharge surface, and the main unit orifice is provided by the connecting orifice 12-3 provided in the horizontal direction.
12-1 and this connection orifice 12
Reference numeral -3 denotes the flow of the molten polymer for the light-shielding auxiliary portion 3 and the flow of the molten polymer for the light-transmitting main portion 2 only at the shoulders of the orifices 12-1 and 12-1 for the main portion, preferably only at the shoulders. Has an opening for injection in a direction transverse to the flow.

Here, the light-shielding auxiliary portion 3 is formed in an eight-shape around the periphery of the strand excluding the light emitting portion in the cross section on the light emitting side,
In addition, in order to dispose it accurately and uniformly along the length direction of the strand, a spinneret 12 as shown in FIGS. 4 and 5 is used, and each of the light-transmitting main portion 2 and the light-shielding auxiliary portion 3 It is desirable that the molten polymer be compounded in the flow path of the light-transmitting main portion orifice 12-1.

According to these methods, the positional accuracy of the light-shielding auxiliary portion 3 in the cross section of the strand can be sufficiently maintained, and the light-shielding auxiliary portion 3 flows into the valley between the adjacent light-transmitting main portions 2. The bonding between the sex assisting parts 3 can be easily performed.

As the spinneret 12, a large number of orifices 12-1, 12-1,... For the main part are continuously arranged in a ring shape. When the spinneret is heated, each of the orifices 12-1, 12-1,. The temperature distribution becomes uniform, and as a result, there is no unevenness between the weights of the translucent strand 1 at the time of melt extrusion, and the translucent strand 1 having a uniform shape and no twist can be obtained. However, in the present invention, it is also possible to use a spinneret in which the orifices are arranged in a substantially horseshoe shape or on a straight line. In addition, at the time of melt extrusion, a metering pump may be provided in order to secure the stability of the discharge amount.

In order to join the melt-extruded strands 1, 1,..., A large number of the extruded strands 1, 1,. Although it is possible to carry out by a method of fusing, it is preferable to carry out using a so-called Belas effect.

Also, when a large number of annularly extruded molten strands 1, 1,... Are heated at a temperature equal to or higher than the glass transition point of the translucent main body 2, the emission side of the projection screen is first and second ring guides. It is also advantageous to join adjacent strands 1 and 1 while taking them in such a way that they come into contact with the insides of the 14,15. In this case, the tension of the two ring guides 14 and 15 can be stabilized to stabilize the tension.

As a result, the annular sheet formed from a large number of molten strands 1, 1,... Is transferred from the annular shape to a flat surface by a trowel-shaped guide 16 provided below ring guides 14, 15 (downstream of the process). When the sheet is unfolded, the fluctuation in tension applied to the sheet is suppressed from affecting the discharge section, and the difference in strand pitch between the center and the end of the obtained sheet is reduced, enabling strand extrusion under stable conditions Becomes

When one annular ring is used, if the width of the sheet developed from the annular shape to the planar shape becomes large, the operating conditions for continuously performing the stable extrusion of the molten strand for a long time, for example, an allowable condition. Strand extrusion conditions, the position range where the ring is installed, and the like are narrowed.

In such a case, if the second ring guide 15 having a smaller diameter than the first ring guide 14 is installed below the first ring guide 14 (downstream of the process) as shown in the illustrated example, it can be adopted. Operating range has expanded, and at the same time
By adjusting the interval between the ring guide 14 and the second ring guide 15, the range of the strand pitch that can be manufactured is widened, and a sheet with higher precision and less pitch unevenness can be obtained. The inner diameter of each ring guide and the position from the spinneret can be adjusted as needed.

The translucent strand 1 comprises a first ring guide
14 and the second ring guide 15 are taken along the inner wall, respectively, and are iron-shaped guide 16 and rod-shaped straight guide 17.
Is transformed from an annular sheet into a flat sheet,
At the same time, the traveling direction of the sheet is changed by a rod-shaped straight guide 17, the sheet is taken up by a nip roller 18, and the winding machine 19
And it becomes a projection screen. When the projection screen made of the sheets formed in this manner is attached to a color projection television, a screen with less disturbance and a high resolution can be obtained.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiment. In this embodiment, a projection screen as shown in FIG. 1 is used by using an apparatus as shown in FIGS. 3, 4, and 6 to 9. Was made.

FIG. 4 shows a main part of the spinneret 12 used.
The orifices 12-2 for the light-shielding auxiliary portion are connected to each other in a ring shape. The orifice 12-1 for the main body (pore diameter 1 mm, 1.15 mm pitch) is filled with a melt of a mixture of polycarbonate (Mitsubishi Gas Chemical Co., Ltd., Iupilon # 2000) and 4% by weight of inorganic silica in one orifice. 0.5 g / min per unit, and a connection orifice 12-3 (aperture of 0.50
mm), a melt of a mixture obtained by further adding 2% by weight of carbon black to the above polycarbonate mixture was supplied at a rate of 0.05 g / min per connection orifice.
Extruded downward at 0 ° C.

After the extrusion, the annular sheet formed by joining (fusing) the strands is applied to the first ring guide 14 having an inner diameter of 30 cm.
The iron-shaped guide 16 is then taken up along the inner wall of the second ring guide 15 having an inner diameter of 15 cm at a speed of 3.4 m / min.
And a bar-shaped straight guide 17 to form a flat sheet. The four types of guides 14 to 17 all have 20
The sheet was cooled through warm water at ℃.

In the sheet thus obtained, 1000 light-transmitting strands having a diameter of 0.4 mm are uniformly arranged on a plane, and the light-exit side of the strand is the periphery of the strand excluding the light-exit portion. A light-shielding auxiliary portion 3 was formed in the portion in an eight-shaped cross section.

Next, this sheet was made wide by an apparatus as shown in FIG. 9 to produce a transmission type projection screen. That is, three sheets are taken out from the roll 22 set on the creel stand using the first nip roller 23, and the first far-infrared heater at an atmospheric temperature of 140 ° C.
The inside of the sheet 24 is passed through a second nip roller 25 while being stretched 1.05 times to remove curling of the sheet.
Of the second far-infrared heater 26 while being extended by 1.1 times to further heat, and immediately the curved bar-shaped bending guide 27
Melt bonding while bringing the sheets close together,
It was supplied to the cutter 29 at a predetermined speed and cut into a length of 1 m.

When the obtained projection screen was mounted on a color projection television and observed, a bright, clear, and excellent color tone and contrast screen was obtained not only from the front but also from an oblique direction.

[0042]

As described above in detail, according to the present invention, (1) a double-sided lenticular projection screen having an extremely small lenticular lens pitch can be manufactured. (2) In particular, a two-stage contact type ring guide is used. (3) When the guide is cooled, a screen having a good surface condition is obtained. (4) The first ring guide and the second ring guide By adjusting the distance between the ring guides and the inner diameter of the second ring guide, the strand pitch can be freely set. (5) Since the light-shielding auxiliary portions can be uniformly arranged on the strand, there are advantages such as obtaining a projection screen with good contrast.

[Brief description of the drawings]

FIG. 1 shows a production method of the present invention using the spinneret of the present invention.
FIG. 4 is a schematic cross-sectional view showing a part of an example of a projection screen manufactured by a method .

FIG. 2 shows a production method of the present invention using the spinneret of the present invention.
It is a typical sectional view showing a part of other example of a projection screen manufactured by the method .

FIG. 3 is a schematic side view of an example of an apparatus used to carry out the method of the present invention.

FIG. 4 is a schematic structural view showing an example of a spinneret according to the present invention.

FIG. 5 is a schematic structural view showing another example of the spinneret according to the present invention.

FIG. 6 is a schematic sectional view of a first ring guide example used in the method of the present invention.

FIG. 7 is a schematic sectional view of a second ring guide example used in the method of the present invention.

FIG. 8 is a schematic sectional view showing an example of a trowel-shaped guide used in the method of the present invention.

FIG. 9 is a schematic side view of an apparatus for manufacturing a wide projection sheet by joining narrow sheets.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Translucent strand 2 Translucent main part 3 Light-shielding auxiliary part 11 Extruder 12 Spinneret 12-1 (light-transmitting) main part orifice 12-2 (light-shielding) auxiliary part flow path 12-3 Connection Orifice 13 Spinneret holder 14 First ring guide 15 Second ring guide 16 Iron guide 17 Bar-shaped straight guide 18 Nip roller 19 Winder 22 Roll 23 First nip roller 24 First infrared heater 25 Second nip roller 26 Second Infrared heater 27 Flexure guide 28 Third nip roller 29 Cutter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-245235 (JP, A) JP-A-2-146536 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03B 21/56

Claims (5)

(57) [Claims] 1. A number of orifices for extruding a molten polymer for a light-transmitting main portion, which are open to the discharge surface of a spinneret, and (b) a molten weight for a light-shielding auxiliary portion. has a flow path for the flow of coalescing, and a connecting orifice connecting the lower end portion and an orifice for the light-transmitting main portion of the flow path for (c) the shading auxiliary unit, (d) the The connecting orifice extends in an inclined state to an intermediate position between the adjacent orifices for the light-transmitting main body, and (e) the connecting orifice is located slightly before the spinneret discharge surface. An opening is formed at the shoulder of the orifice for the light-transmitting main portion so that the molten polymer for the light-shielding auxiliary portion is injected into the flow of the molten polymer for the light-transmitting main portion along the flow. A spinneret for manufacturing a projection screen. 2. A large number of orifices for extruding a molten polymer for a light-transmitting main part, which are open to the discharge surface of a spinneret, and (b) slightly smaller than the spinneret discharge surface. A flow path for flowing the molten polymer for the light-shielding auxiliary portion, which is provided extending parallel to and perpendicular to the orifice for the light-transmitting main portion to a position in front thereof; has a connecting orifice connecting the lower end portion and an orifice for the light-transmitting main portion of the flow path of the auxiliary unit, a, (d) the connecting orifice is extended horizontally, moreover (e) , The connecting orifice is the spinneret discharge surface
Slightly before this, the molten polymer for the light-shielding auxiliary portion is injected into the shoulder of the orifice for the light-transmitting main portion in a direction crossing the flow of the molten polymer for the light-transmitting main portion. A spinneret for producing a projection screen, characterized in that the spinneret has an opening. 3. A method for producing a projection screen by discharging a thermoplastic polymer in a molten state from a spinneret having a number of orifices to form a number of plastic-based light-transmitting strands or a sheet comprising these strands. In the above , using the spinneret according to claim 1 or 2, the molten polymer forming the light-transmitting main portion and the light-shielding auxiliary portion from the orifice, respectively, and the light-shielding auxiliary portion is the light emitting side of the strand. And simultaneously ejecting the liquid crystal so that the cross section is arranged in an eight-shape at both peripheral parts except for the light emitting part. 4. Using the spinneret in which the plurality of orifices are arranged in an annular shape, passing the formed annular sheet through a ring guide disposed below or above the spinneret, and then forming the sheet into a planar shape. 4. The method according to claim 3 , wherein the projection screen is deformed. 5. The method according to claim 1, wherein the annular sheet is first passed through a first ring guide, then passed through a second ring guide having a smaller diameter than the first ring guide, and then deformed into a planar shape. A method for manufacturing a projection screen according to claim 4 .