JPS599649A - Transmission type projection screen - Google Patents

Abstract

PURPOSE:To reduce the thickness of a device and to guide projection light effectively in an observation direction, by arranging the light-transmissive surface having a saw-tooth wave in cross section whose slanting surfaces and vertical surfaces are formed at nearly equal angles and pitch repeatedly, at least on an incident light source side. CONSTITUTION:Vertical surfaces 7 perpendicular to the flat rear surface of a screen 4' and slanting surfaces 8 having a specific angle are arranged alternately at nearly equal pitch to form the saw-tooth wave section. Light beams 9, 10, and 11 incident to the light-transmissive screen 4' are refracted in incidence and projection to obtain projected light beams 9', 10', and 11', and even when they are incident slantingly to the normal of the screen 4, they are refracted and projected in parallel to the normal, so mirrors 2' and 3', and surfaces 5' and 6' are arranged nearly in parallell, reducing the depth of the device. The slanting surfaces and vertical surfaces of the saw-tooth wave section are adjusted to refract the projected light to an observers' position.

Description

[Detailed Description of the Invention] Projection light tw! This invention relates to a transmission type projection screen suitable for effectively refracting light in the festival direction. In particular, the transmission type projection screen of the present invention is suitable for manufacturing a projection type television device in a thin and compact manner.

Conventionally, when projecting onto a transmission type projection screen using a projection device, the incident light is made to be incident so as to substantially coincide with the normal direction of the transmission type projection screen. By doing this, the incident light can be effectively emitted to the observation position,
In particular, by increasing the distance between the projection device and the transmission type projection screen, the diffusion angle of the emitted light can be reduced. FIG. 1 is a schematic diagram showing the structure of a conventional projection type TenVision device, in which projection light emitted from an image projection device 1 is reflected by a mirror and 3 and is observed through a transmission type projection screen TL. As is clear from Figure 8gl, Mirror Co and Mirror 3 must be installed at an angle to the front S and back B of the projection television device, and the size of the screen q, that is, the size of the screen, is large. In this case, Mirayu and 3 will inevitably become thicker (the overall size of the projection type television device, especially the first
The unavoidable drawback is that the depth, expressed by the length in the left and right directions in the figure, is too large.

The present inventor conducted research in view of the above drawbacks.

By using a sawtooth light transmitting surface formed by repeating slopes and vertical surfaces, the projection direction of the mirror 3 does not have to be adjusted in the normal direction of the screen as in the prior art; for example, in the device shown in FIG. It was discovered that the projection light can be effectively guided in the observation direction, and that the device can be made thinner than conventional devices, and the present invention has been achieved.

That is, the main idea of the present invention is to provide a transmission projection screen Y, which has a light transmitting surface having a serrated cross section, which is repeatedly formed at a pitch and angle equal to the slope and the vertical surface, and disposed at least on the incident light source side. It is something.

The present invention will be explained in detail below. [6] Fig. 2 is a sectional view showing an example of the screen of the present invention. The screen shown in Fig. 2 is formed so that the slopes g and the slopes g have a serrated cross section, and the slopes and the vertical directions are formed alternately. One combination unit consisting of (8) is formed repeatedly at a pitch equal to y. The screen shown in Fig. 2 can be formed using a known light-transmitting substrate.The light-transmitting substrate may be colorless and transparent, or may be made of a material such as glass beads, silica powder, etc. It may be a blended one, or one or both surfaces may have light diffusing properties.When a ray of light 9,l01l/ is incident on such a screen from the left side in the middle of the drawing, it is incident on the screen. It is refracted when entering and exiting, 9', 10/, / /'
We should be able to obtain an output beam like this.

Figures 3 and 74 show other examples of screens of the present invention; in Figures 2 and 74, screens of the shape shown in Figure 2 are used simply for refracting light rays; , which uses such a refracting plate in combination with a known transmission type projection screen, and in FIG. 3, the refracting plate has a serrated cross-sectional shape. 4) is used with the light source facing the incident light side, and in FIG. 74 facing the output side. In both FIGS. 3 and 74, the refracting plate 12'Y is used facing the incident light side, with the front and back sides being different. As the transmission type projection screen denoted by the reference numeral 13, it is possible to use any known type of projection screen, and it is possible to use one that simply has light diffusing properties, one that has a circular shape or an innumerable number of lenses, etc. It may be a combination of lenses, or it may have a light-shielding layer (usually called a black stripe) that prevents stray light and reflected light from forming in unnecessary areas. In addition, the transmission type projection screen 13 may be provided on the front surface of the above-mentioned various lenses, light-diffusing surfaces, or black stripes of Y/sheet of light-transmissive substrates, or It may be provided separately as appropriate. Fig. S shows a typical example of the transmission type projection screen shown in Fig. 3 or Fig. 74.
and lenticular sea)/4'! 'It is a combination of things. Although not shown in Section 1, the surface of the refracting plate having a sawtooth cross-sectional shape may face opposite to that shown in FIG. S, that is, face the Fresnel lens sheet 13 side.

Furthermore, a light transmitting surface with a sawtooth cross section, another V lens surface and Y1
It may be provided on the front and back sides of a single light-transmissive substrate. FIG. 6 shows the simplest example, in which the lens sheet/A consists of a mine-shaped cross-section 17 and a Fresnel lens concave 1g. Or, as shown in Figure 7, a lenticular lens surface (0°) on one side of the lens sheet (11σ) on the opposite side.
It may also be used in combination with a lenticular lens provided with a light shielding layer in the non-light condensing portion.

By using a tooth-shaped light transmitting surface at least for incident light (111IK), as shown in Fig. 5, light that is not parallel to the normal line of the screen, and is incident obliquely from below, is transmitted to the part of the screen J. is refracted and emitted in a direction parallel to the normal line of the y-screen, so the conventional first
Since it is not necessary to use a mirror to direct the light beam in the normal direction of the screen as in the device shown in the figure, the mirror J
' and J can be installed parallel to y on the front y and back 6', so it is sufficient to install the Katazuka projection device /' have a link.

It should be noted that the sawtooth cross section is formed by an inclined surface and a vertical direction. It is also possible to set the television device W above or below the viewer's position 1u and refract the emitted light Y toward the viewer's position by appropriately adjusting the A section.

[Brief explanation of the drawing]

Fig. 41 shows the structure of a conventional projection type television device. [Figs. 2 to 8g7 are schematic diagrams, and Figs. 1 is a schematic diagram showing the structure of a projection type television device using a transmission type projection screen. ll/......Image projection device+2. (3,3
I0...ζ2Q II'...Screen 7...
・・・・・・・・・Vertical orientation・・・・・・・・・・・・Slope 9 ・・・・・・・・・・・・Light transmittance with light diffusing properties Board diagram 1 Figure 2 Figure 8 Figure 4 Figure 5 Figure 0 Figure 7 Figure 295-Figure 8

Claims (1)

[Claims] (1) A transmissive projection screen in which the inclined plane and the vertical plane have a small number of light transmitting surfaces (both on the side of the incident light source) with tooth-shaped cross-sections that are repeatedly formed at the same pitch and angle.