JPH04174828A - Protection film and document film projecting method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a protective film for protecting an original to be projected using an overhead projector, and a method for projecting an original film.

(Prior art) As a means of protecting a document for use with an overhead projector, two transparent polyester films are placed on the top and bottom surfaces of the document, sandwiched between paper frames, and then affixed with sellotape or the like. is common,
The transparent polyester film to which the paper frame is attached is used as a protective film, and the protective film is placed on the document table of an overhead projector to project the image.

However, if the size of the projection area of the light beam emitted from the light source of the overhead projector onto the document glass, which is the film setting surface, is larger than the size of the paper frame mentioned above, there will be an empty space corresponding to that size in the projection area of the document glass. There is a problem in that blank areas in the projection area outside the paper frame are projected as white areas on the projection surface projected onto the screen.

To deal with this problem, you can adjust the size of the paper frame to the maximum size of the effective projection area of the document table of the overhead projector to prevent this white area, or set the size of the paper frame to If the size of the area is smaller than the maximum size, when the paper frame is placed on the document table, fill the small empty space on the document table with opaque or non-light-permeable paper, etc. It was being done to fill in the information.

(Objective of the Invention) The present invention provides a protective film and a method for projecting a manuscript film that fills the above-mentioned white part of the manuscript table, which is the film setting surface (placement surface), without taking these special measures. It is intended to.

(Structure of the Invention) In order to achieve the above object, the present invention provides a protective film consisting of two openable and closable polarizing films sandwiching an original film for projection between them, the two polarizing films being in a closed state. In one case, the polarizing axes of the respective polarizing films are configured to intersect with each other, the surfaces of the two protective films are formed with at least two windings that intersect with each other, and the polarizing axes are orthogonal to each other. That, projector
A first polarizing film that covers the entire maximum effective projection area on the document placement surface is placed on the document placement surface, and the document film scatters the light beam emitted from the light source and projects it onto the screen of the projector. placed on the polarizing film,
A second polarizing film covering the entire area of the maximum effective projection area is placed over the original film so that the polarization axes of the optical films on both sides intersect, and the first polarizing film, the original film, and the second polarizing film are The present invention is characterized in that the film is projected onto the screen by a beam of light emitted from the light source, and that the optical axes are orthogonal to each other.

(Example) Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is an exploded perspective view showing the configuration of an embodiment of this technology.

In this figure, reference numeral 1 denotes an original film (original) having an image to be projected onto a screen by an overhead projector, 2 denotes a polarizing plate or polarizing film which is an upper protective film covering the upper surface of the original film 1, and 3 denotes a polarizing film. This is a polarizing plate or a polarizing film that is a lower protective film that covers the lower surface of the original film 1. The upper protective film 2 and the lower protective film 3 are arranged so that their optical axes intersect. The polarization axis refers to the same direction as the vibration direction of polarized light. Therefore, if an attempt is made to overlap the upper protective film 2 and the lower protective film 3 to allow light to pass through the films, the transmission of light will be blocked because the intersection angles of the polarization axes are misaligned. In particular, when the angle of intersection between the two is 90 degrees, it looks black.

FIG. 2 is a diagram showing this state. In Figure 2, A
B shows the light transmission state of the part where the original film 1 is sandwiched between two polarizing films. In the peripheral area (area where the two polarizing films directly face each other), the light is not transmitted.

This area B visually appears black.

The extent of the spread of this polarizing film surface is defined as the maximum area covered by the light beam from the projector's light source on the document table, which is the film mounting surface, that is, the maximum effective projection area.

Furthermore, when the original film l for an overhead projector is sandwiched between the upper protective film 2 and the lower protective film 3, the light 21b from the light source is polarized by the lower protective film 3, as shown in FIG. is scattered by the original film 1 for the overhead projector which has a scattering property, and the vibration direction of the light becomes multidirectional again. Among this scattered light, the valve vibration component that matches the polarization axis of the upper protective film 2 Only light that has a value is transmitted.

When the surface of the original film 1 is roughened in only one direction, the scattering effect due to the roughness cannot be obtained if the direction of the roughness coincides with the direction of the polarization axis of the polarizing film on the light exit side. The polarized light incident on the original film 1 is blocked from passing by the polarizing film on the exit side. However, if the roughening is applied in at least two intersecting directions, the polarized light passing through the document will be scattered due to the scattering effect of the roughening direction that does not match the direction of the polarization axis, and a component will be generated that passes through the polarizing film on the exit side. If roughness is applied in multiple directions that intersect with each other, scattered light originating from directions other than one direction that coincides with the direction of the polarization axis of the polarizing film on the exit side will contribute to passing toward the exit side.

As a result, the transmitted light 21b of the light source comes only to the position between the upper protective film 2 and the lower protective film 3, where the original film 1 for the overhead projector is present. In addition, in the area where the original film l for the overhead projector is not present, the light 21a of the light source is
After passing through the lower film 3, the polarized transmitted light passes through the area where the original film 1 is not present and reaches the film 2, so the transmitted light 21a is attenuated by the polarization effect with a polarization angle of 90°. It turns out. As a result, the projection screen 12 of the overhead projector 13 shown in FIG. 4 is displayed between the protective film 2.3 of the present invention shown in FIG. Only one portion of the sandwiched original film will be projected.

Regarding the area of the polarizing film that covers the maximum effective projection area on the document table where the original film is not sandwiched, the intersection angle of the optical axes of the upper and lower polarizing films 2.3 on both sides is 90°.
Therefore, since the light from the light source passing through the area is attenuated, the transmitted light does not reach the projection screen 12, so that only the area of the original film 1 is projected.

FIG. 5 shows an embodiment of a method for projecting an original film, in which two protective polarizing films, which are connected at one end so that they can be opened and closed, are opened and closed, and the original film is sandwiched therebetween and projected. code 4.5
is a protective polarizing film. The two polarizing films 4.5 are stacked one on top of the other and are thermally fused at positions C and D on one edge thereof. When sandwiching the original film 1, open one end opposite to the heat-sealed edge of the two protective polarizing films 4.5 and insert the polarizing film 4.
The original film 1 is inserted between the original film 1 and the polarizing film 5, and one open edge is closed at a desired position of the polarizing film area, and the original film 1 is sandwiched at the desired position. The polarizing film 4
Of course, the polarization axes of and 5 intersect with each other.

Similarly, the protective polarizing film and the document film for overhead projector may not be separated, but may be combined into one set.

FIG. 6 shows how the polarization axes of the upper polarizing film 6 and the lower polarizing film 7 intersect. FIG. 5A shows a state in which the respective polarization axes are parallel.

The polarized light of the valve vibration that has passed through the polarizing film 6 also passes through the polarizing film 7, and the polarized light of the corresponding vibration is obtained. Figure (b) shows a state in which the axes are orthogonal. The polarized light of the valve vibration that has passed through the polarizing film 6 is prevented from passing through the polarizing film 7.

FIG. 7 shows an overhead projector to which an embodiment of the present invention is applied. Figure (a) shows a reflection type overhead projector. Reference numeral 8 is a light source, 9 is a main body of the projector, and 10 is an original table. In the same figure (bl is a transmission type overhead projector. 11 is a light source, 16 is a main body, and I7 is an original platen. This protective film is placed on the original platens 1o and 17 together with the original film, and the screen (not shown).

Note that this technique can also be applied to a slide projector.

(Effects of the Invention) As described above, according to the present invention, by using two polarizing plates arranged with their polarization axes shifted as the upper protective film and lower protective film for sandwiching the original,
The polarizing plate prevents the light beam from the projector's light source from passing through the maximum effective projection area on the film setting surface (mounting surface), excluding the area of the original film that is the projection object, and the film on the film setting surface The non-existent area is visually projected darkly. Furthermore, it is no longer necessary to place a light shielding object in the vacant area of the document table based on the difference between the size of the protective film and the size of the maximum effective projection area on the document table in order to visually darken the non-existent area.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the configuration of an embodiment of the present invention, and FIG. 2 is an outer U section showing the state of light transmission in the embodiment of the present invention.
FIG. 3 is a sectional view showing the state of light passage according to the embodiment of the present invention;
Fig. 4 is a diagram showing the configuration of an overhead projector to which an embodiment of the present invention is applied, Fig. 5 is a diagram showing another embodiment of the invention, and Fig. 6 is a diagram showing the crossing state of the polarization axes of the polarizing film. 7(a) is a diagram showing a reflection type overhead projector to which the present invention is applied. , the same figure ibl is a diagram showing a transmission type overhead projector to which the present invention is applied. 1... Document film for projector, 2... Upper protective film, 3... Lower protective film, 4 .5・
...Polarizing film for protection, 6...Polarizing plate of the upper @sample film, 7...Polarizing plate of the lower protective film, 8...
Light source, 9... Reflective overhead projector,
1o... Mounting table, 11... Light source, 12... Projection screen, 13... Overhead projector-1
Work 4...Placement table, 21a...Light, 21b...Light.

Claims (5)

[Claims] (1) A protective film consisting of two openable and closable polarizing films that sandwich an original film for projection between them, and when the two polarizing films are in a closed state, the polarization axes of the polarizing films are mutually aligned. A protective film characterized by having a cross-sectional structure. (2) The protective film according to claim (1), wherein the surfaces of the two protective films are formed with roughness in at least two directions that intersect with each other. (3) The protective film according to claim (1), wherein the polarization axes are perpendicular to each other. (4) A first polarizing film covering the entire maximum effective projection area on the document placement surface of the projector is placed on the placement surface, and the light beam emitted from the light source is scattered and projected onto the screen of the projector. placing an original film overlappingly on the polarizing film, and placing a second polarizing film covering the entire area of the maximum effective projection area over the original film so that the polarization axes of both polarizing films intersect; A method for projecting an original film, comprising projecting the first polarizing film, the original film, and the second polarizing film onto the screen using a beam of light emitted from the light source. (5) The method for projecting a protective film and original film according to claim (4), wherein the optical axes are orthogonal to each other.