JPH08129229A - Plastic sheet for projection screen - Google Patents

Abstract

PURPOSE: To eliminate the need for executing secondary working after molding and to execute holding by a supporting frame as it is by previously forming through-holes penetrating from the front to the rear in outer peripheral part. CONSTITUTION: This plastic sheet 1 is a sheet made of a polymethyl methacrylate and through-holes for holding are previously molded at prescribed intervals. This process for production comprises fitting a member 6 consisting of a foamed urethane resin, etc., and having elasticity to a recessed part with which a projecting part 4 formed in an upper metal 3 comes into contact. The upper metal mold 3 and a lower metal mold 5 are disposed to face each other via a gasket 7 consisting of the foamed urethane resin, etc. At this time, the projecting part 4 formed at the upper metal mold 3 is arranged in such a manner that this projecting part comes into contact with the elastic member 6 disposed on the lower metal mold 5. Acrylic syrup essentially consisting of a methyl methacrylate monomer is poured therein. This syrup is heated and cured to obtain the plastic sheet 1 having the through-holes for holding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various lens sheets constituting a projection screen and a plastic sheet for a projection screen such as a sheet arranged on the front surface of the lens sheet for protecting the lens sheet, and more particularly to a supporting frame or the like. The present invention relates to a plastic sheet for a projection screen, which is used by being fixedly supported on.

[0002]

2. Description of the Related Art As a projection screen (hereinafter simply referred to as a screen) used for a rear projection type television, optical elements such as a Fresnel lens, a lenticular lens, a prism, a diffusion layer and a light shielding layer are provided on at least one surface. It is known that a plurality of formed plastic sheets are combined to obtain desired optical characteristics. In addition, in order to prevent the plastic sheet on which these optical elements are formed from being damaged or soiled during its use, a hard coat, antistatic, antireflection is applied on the front surface of the plastic sheet on which the optical elements are formed. It has been practiced to dispose a translucent protective plastic sheet that has been subjected to such treatments.

A screen using such a plastic sheet needs to be held as flat as possible in order to project an image, and a plurality of screens such as a screen in which a Fresnel lens sheet and a lenticular lens sheet are superposed on each other are required. In a screen including a combination of plastic sheets, a plurality of plastic sheets must be held in close contact with each other or maintained at a predetermined distance. On the other hand, a plastic sheet may expand or contract due to changes in the temperature and humidity of the environment in which it is installed, which may cause bending or wrinkling, which deteriorates the flatness of the screen or creates gaps between multiple plastic sheets. Therefore, there is a problem in that the image quality is deteriorated.

In order to solve such a problem, particularly when flatness is required, as proposed in Japanese Utility Model Publication No. 3-103436, Japanese Utility Model Publication No. 105839, Japanese Utility Model Publication No. 3-108236, etc. In this method, a plastic sheet is hung and the tension is generated by using the plastic sheet's own weight to secure the flat surface, or a mechanism for applying tension in the outer peripheral direction is provided to further ensure the flat surface. Is used.

For this purpose, it is necessary to fix the plastic sheet to the support frame or the like at the upper end or the like, and in order to provide a through hole in the outer peripheral portion such as the upper end of the plastic sheet or to reinforce the through hole. A holding member such as a clasp has been attached. FIG. 5 is a diagram showing an example of a screen having such a support structure. FIG. 5 (a)
In the above, the through hole 32 is provided at the upper end of the plastic sheet 31, and the plastic sheet 31 is provided between the support frames 33.
Through-hole 3 provided in the support frame 33 with the
4, holding bolts 35 are inserted through the through holes 32 of the plastic sheet 31, and fixed with holding nuts 36 from the opposite side. The lower end of the plastic sheet 31 is also stretchably held between the lower portions of the support frame 33, and tension is applied by the weight of the plastic sheet to maintain the flatness. In FIG. 5 (b),
At the upper end of the plastic sheet 41, a ring-shaped fixing metal member having a threaded inner surface is embedded as a holding member 49, and is fixed to the support frame 43 by a holding bolt 45. The structure of the lower end is the same as in the case of FIG.

[0006]

Conventionally, in order to fix a plastic sheet with such a structure, when a through hole is provided in the outer peripheral portion of the plastic sheet or a holding member is embedded, the plastic sheet is firstly attached. After molding, after that, as a secondary processing, drilling processing was performed. The plastic sheet used for the screen has an extremely large area of 2 m × 2 m or more, whereas the thickness is extremely thin, about several mm, and the sheet strength is reduced due to variations in processing accuracy. However, there is a problem in that the work may be complicated and the work may be complicated and scratched. Further, in order to perform the secondary processing of such a large plastic sheet, a large work space is required, and the cost increase of the secondary processing is large, which is a problem. An object of the present invention is to provide a plastic sheet for a projection screen that solves such a problem.

[0007]

In order to solve the above-mentioned problems, the first invention of the present application is provided with an optical element on at least one surface, or a plastic sheet for a projection screen for protecting the optical element. In the above, the plastic sheet for a projection screen is characterized in that a through hole penetrating to the front and back is formed in the outer peripheral portion in advance.

A second invention of the present application is a plastic sheet for a projection screen, which is provided with an optical element on at least one surface thereof or which protects the optical element, for holding the plastic sheet in the outer peripheral portion in advance. A plastic sheet for a projection screen, wherein a member is embedded and molded, and the openings of the holding member are arranged so as to form through holes on the front and back of the plastic sheet.

In a third aspect of the present invention, the plastic sheet is cast-molded or injection-molded, and is insert-molded with a holding member inserted therein. It is a sheet.

[0010]

In the first invention of the present application, by forming the holding through hole in the outer peripheral portion at the same time when the plastic sheet for a projection screen is formed, the secondary processing becomes unnecessary, and a problem occurs with the secondary processing. Can be solved. In the second invention of the present application, simultaneously with the molding of the plastic sheet for a projection screen,
Since the holding member such as the clasp is embedded in the outer peripheral portion, the secondary processing is not necessary, and the problem that occurs with the secondary processing can be solved. In the third invention of the present application, the plastic sheet is composed of a cast molded product or an injection molded product, and a holding member is further installed in the molding die, and the resin is poured into the molding die and cured by insert molding. Since the holding member is embedded at the same time as the molding, the secondary processing becomes unnecessary, and the problems that occur with the secondary processing can be solved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a diagram showing a first embodiment of the present invention.
1A is a plan view of the plastic sheet of the present invention, FIG.
(B) shows sectional drawing cut | disconnected by the AA 'line, respectively.
The plastic sheet 1 is a polymethylmethacrylate sheet having a width of 2600 mm × a length of 2000 mm and a thickness of 6 mm, and through holes 2 for holding are preliminarily formed at a position of 25 mm from the upper end thereof at intervals of 600 mm.

Although not shown in FIG. 1, a circular Fresnel lens, a linear Fresnel lens for focusing light in the vertical direction, is provided on the front surface or the back surface of the plastic sheet 1.
A linear Fresnel lens that collects horizontally, a prism lens that refracts the optical axis of the projected light upward or downward, an array of lenticular lenses that diffuse the projected light horizontally, and a lenticular lens that diffuses the projected light vertically. Arrayed, fly-eye lens, isotropic and anisotropic diffusion surfaces, optical elements such as black stripes and other light-shielding layers, as well as antistatic film, antireflection film, hard coat, etc. It is possible to combine the front surface and the back surface with the above optical elements and treatments selected according to the purpose.

FIG. 2 is a diagram for explaining the method of manufacturing the plastic sheet of the first embodiment. FIG. 2A shows an upper mold 3 used for cast molding, and a convex portion 4 is provided at a portion corresponding to a position where the through hole 2 of the molded product is provided. Figure 2
(B) shows the lower die 5, and the elastic and stretchable member 6 (hereinafter referred to as the stretchable member) made of urethane foam resin or the like is in contact with the convex portion provided on the upper die. It is fitted in a recess provided in the mold. This elastic member 6
Has the function of absorbing the shrinkage of the molding material that occurs during cast molding. FIG. 2C shows a state in which the upper mold 3 and the lower mold 5 are opposed to each other via a gasket 7 made of urethane foam resin or the like to form cells for cast molding. The convex portion 4 provided on the upper mold 3 is arranged so as to abut the elastic member 6 provided on the lower mold 5. Further, the gasket 7 is installed so that its inner size corresponds to the desired size of the plastic sheet, and the gap between the two molds is installed so as to correspond to the desired thickness of the plastic sheet. It is necessary to make a correction in consideration of expansion and contraction of the molding material. In this example, an acrylic syrup containing a methyl methacrylate monomer as a main component was poured, and this was heated and cured to obtain a plastic sheet having through holes for holding. The plastic sheet 11 thus obtained did not require secondary processing, was free from scratches, and showed good quality. In addition, this sheet is shown in FIG.
When it was held in the same manner as shown in (a), no accident such as breakage of the plastic sheet due to variation in accuracy of secondary processing occurred.

Second Embodiment FIG. 3 is a diagram showing a second embodiment of the present invention.
3A is a plan view of the plastic sheet of the present invention, FIG.
(B) Cross-sectional views taken along the line AA 'are respectively shown. The plastic sheet 11 is a sheet made of polymethylmethacrylate and having a width of 2600 mm × a length of 2000 mm and a thickness of 4 mm, and a holding member 19 made of an annular brass with an inner surface being threaded at a distance of 600 mm at a position 30 mm from the upper end thereof.
However, the opening is arranged and embedded so as to form a through hole 12 that penetrates the front and back of the plastic sheet 11, and is molded.

Although not shown in FIG. 3, a circular Fresnel lens, a linear Fresnel lens that vertically collects light, a linear Fresnel lens that horizontally collects light, and a projection light A prism lens that refracts the optical axis upward or downward,
Arrangement of lenticular lenses that diffuse the projection light in the horizontal direction, arrangement of lenticular lenses that diffuse the projection light in the vertical direction, fly-eye lens, isotropic diffusion surface, anisotropic diffusion surface, light shielding such as black stripe In addition to optical elements such as layers, antistatic film, antireflection film, hard coat, and other treatments can be performed. For each of the front surface and the back surface, select one from the above optical elements and treatments according to the purpose. Can be combined.

FIG. 4 is a diagram for explaining the method of manufacturing the plastic sheet of the second embodiment. FIG. 4A shows an upper mold 13 used for cast molding, and a concave portion 18 is provided at a portion corresponding to a position where the holding member 19 is inserted.
FIG. 4 (c) shows the lower mold 15, and like the upper mold, a concave portion 18 is provided at a portion corresponding to the position where the holding member 19 is inserted. FIG. 4B shows a state in which elastic and stretchable members 16 (hereinafter referred to as stretchable members) made of urethane foam resin or the like are arranged at the upper and lower ends of the holding member 19 for holding. The member 19 is thus inserted into the cell formed by the upper mold 13 and the lower mold 15. The stretchable member 16 has a function of absorbing shrinkage of the molding material that occurs during cast molding. FIG. 4D shows a state in which the upper mold 13 and the lower mold 15 are opposed to each other via a gasket 17 made of urethane foam resin or the like to form cells for cast molding. The concave portion 18 provided on the upper die 13 and the concave portion 1 provided on the lower die 5
The holding member 19 is arranged so that the stretchable members 16 arranged at the upper and lower ends of the holding member 19 are fitted in 8. In the same manner as in Example 1, an acrylic syrup containing a methyl methacrylate monomer as a main component was poured, and this was heated and cured to obtain a plastic sheet having a through hole 12 in which a holding member 19 was embedded. The plastic sheet 11 thus obtained did not require secondary processing, was free from scratches, and showed good quality. Further, when this sheet was held in the same manner as shown in FIG. 5 (b), no accident such as breakage of the plastic sheet due to variation in the accuracy of secondary processing occurred.

[0017]

The plastic sheet for a projection screen according to the present invention can be held by the supporting frame as it is without the need for secondary processing after molding because of the constitution described above. It is possible to eliminate the cost increase associated with processing and shorten the delivery time. In addition, there is no reduction in strength of the machined part due to variations in the accuracy of secondary machining, and no accident such as breakage occurs when it is held and used by the support frame. Furthermore, there is no risk of damaging the plastic sheet and degrading the quality due to the complicated work of secondary processing.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a plastic sheet for a projection screen of the present invention.

FIG. 2 is a diagram illustrating a method of manufacturing the plastic sheet according to the first embodiment.

FIG. 3 is a view showing a second embodiment of the plastic sheet for a projection screen of the present invention.

FIG. 4 is a diagram illustrating a method of manufacturing the plastic sheet according to the first embodiment.

FIG. 5 is a diagram illustrating a support structure of a plastic sheet for a projection screen.

[Explanation of symbols]

1, 11 Plastic sheet for projection screen 2, 12 Through hole 3, 13 Upper mold 4 Convex part 5, 15 Lower mold 6, 16 Stretchable member 7, 17 Gasket 18 Concave part 19 Holding member 31 Conventional plastic Seat 32 Through hole 33 Support frame 34 Support frame through hole 35 Holding bolt 36 Holding nut 41 Plastic sheet 43 Support frame 45 Holding bolt 49 Holding member

Claims (3)

[Claims] 1. An optical element is provided on at least one surface, or a plastic sheet for a projection screen for protecting the optical element is formed with a through hole penetrating to the front and back in the outer peripheral portion in advance. A characteristic plastic sheet for projection screens. 2. An optical element is provided on at least one surface, or in a plastic sheet for a projection screen for protecting the optical element, a member for holding the plastic sheet is embedded in the outer peripheral portion in advance. A plastic sheet for a projection screen, wherein the plastic sheet is formed, and the opening of the holding member is arranged so as to form a through hole in the front and back of the plastic sheet. 3. The plastic sheet for a projection screen according to claim 2, wherein the plastic sheet is cast-molded or injection-molded, and insert-molded with a holding member inserted.