JPS5895725A - Transmission type screen - Google Patents

Abstract

PURPOSE:To elevate contrast and also to raise the mechanical strength of a screen, by providing the second cylindrical lens at an interval exceeding a focal distance from the first cylindrical lens. CONSTITUTION:The first cylindrical lens 2 is a convex lens whose focal distance is (f), and at a position which is at a distance (f) or farther and condenses light from the lens 2, the second cylindrical lens 5 for diffusing this light at a prescribed angle alpha is formed in the concave shape. As a result, even if an incident angle beta is made small, a constant observing angle theta can be secured. Therefore, as for the first cylindrical lens 2, a lens whose lens pitch (p) has the same length as a conventional example and whose incident angle beta is small, that is to say, that which has a long focal distance can be used, it is possible to double thickness (d) of a screen by keeping the lens pitch (p) as it is and without deteriorating its resolution, and the mechanical strength of the screen can be raised.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to - a transmissive screen with black stripes;

Conventionally, as a transparent screen for this dan, patent No. 999
There was a publication dJ4 of No. 74 (Special Publication No. 7-4481). In Figure 1, (1) is a substrate made of acrylic resin, and a cylindrical lens (2), which is a convex lens, is mounted on the incident surface of this substrate (1) on which the image light enters - as shown in Figure 2. Focal length #! ! It is formed by f. Further, on the back surface of the substrate (1), a light transmitting part (8) is provided in the part where the light is focused by the cylindrical lens (2), and a black stripe part (8) is provided in the other part to collect the light. 4) is provided.

In such a pass-through screen, light from a projector (not shown), that is, in the E direction, is collected by a cylindrical lens (2),
It can be used even in a relatively bright room by utilizing the property that all light passes through the transmitting part (8), but all light from sources other than one from the projector is absorbed by the black stripe part (4).

However, in response to light coming from below, which is the observer's side, if the observer's side is bright and the projector side is dark, the transparent part (3) becomes a mirror surface and reflects the light specularly, so the scenery from the observer's side is not reflected. It causes contrast vomiting.

As a means to eliminate the above drawback, the surface 41 of the transparent part (3)
It is conceivable to reduce the size by 181 and increase the surface area S4 of the black stripe part (4). This relationship is the sixth
As shown in the figure. Here, the vertical axis is the brightness when the screen is measured from one direction when light is irradiated from below perpendicular to the transparent part (3), and the brightness when the screen is completely measured from the transparent part (3) under the same conditions. The horizontal axis is the area 84 of the black stripe part (4), which is the gain with respect to the brightness when measured using a reflector.
The ratio is (s4 × 100 (%)) (S, +84 hereinafter referred to as BM rate).

However, if the ratio of the area 84 of the black stripe portion (4) is increased, the thickness d of the screen must be reduced to near the focal point f in order to completely pass the light, as shown in FIG. First, the thickness d of the screen is close to 1.5 cm, which reduces the mechanical strength of the screen. This relationship is expressed by taking the BM rate (%) on the vertical axis and the screen 4 reform (-) on the horizontal axis.
) is shown in FIG. 5 under the condition that the pitch p=0°7-.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transmission screen that has improved contrast and mechanical strength of the screen.

Hereinafter, one embodiment of the present invention will be described according to the TA plane.

In Figure 6, -ti> is an acrylic transparent substrate (2
) denotes a first cylindrical lens arranged in parallel on the incident surface of the substrate (1) on which the image light enters and condenses the image light, and (5) denotes a second cylinder arranged intermittently on the output surface. The lens (4) is a black stripe portion provided on the plane between the adjacent second cylindrical lens +2).

The first cylindrical lens (2) is a convex lens with a focal length f, and the first cylindrical lens
A second cylindrical lens (5) in the shape of a concave lens is provided in a portion where the light from the cylindrical lens (2) gathers to diffuse the light at a predetermined angle.

In the above configuration, the second cylindrical lens (6) acts to scatter the light from the first cylindrical lens (2) by an angle α. This means that even if the angle β of incidence on the second cylindrical lens (5) is reduced, a constant viewing angle θ can be maintained, so the first cylindrical lens In (2), the lens pitch p is the same length as the conventional example,
It is possible to use a lens with a small angle of incidence β, that is, a lens with a long focal point. That is, the screen thickness d can be approximately doubled, as shown in FIG. 7, without deteriorating the resolution due to the lens pitch p, and the screen mechanical Ii! j1! f can be increased.

Furthermore, even if the focal point f of the first cylindrical lens (2) is set close to the screen thickness d, the predetermined viewing angle θ is secured by the second cylindrical lens (5). Cylindrical lens (
6) The area can be reduced, that is, the BM rate can be increased.

Further, the second cylindrical lens (5) has the effect of scattering the disturbance light in one direction, which is the viewer's side, as shown in FIG. 6, and can improve the reduction in contrast due to the disturbance light. For example, at a BM rate of 50%, the light reflection gain on the observer side surface of the conventional screen was 64 as shown in FIG. 5, whereas the light reflection gain of the screen according to the above embodiment was approximately 64. 0.6, and the influence of ambient light could be divided into 1157 areas.

As explained above, according to the present invention, by providing the second cylindrical lens with a distance equal to or longer than the focal length from the first cylindrical lens, it is possible to improve the contrast and increase the mechanical strength of the screen. .

[Brief explanation of drawings]

Figure 1 is a perspective view showing a conventional transmission screen - Figure 2 is a vertical sectional view showing the transmission screen shown in Figure 1, Figure 6 is a characteristic diagram showing the properties of the transmission screen shown in Figure 1, @Figure 4 is a sectional view showing another conventional transmission screen, FIG. 5 is a characteristic diagram showing the properties of a transmission screen, FIG. 6 is a sectional view showing a transmission screen according to an embodiment of the present invention, and FIG. It is a characteristic diagram showing a dark example. (1)...Is plate, tel...first cylindrical lens, (4)...black stripe portion, (6)...
Second cylindrical lens, f...focal length.

Claims (1)

[Claims] (1) On the incident surface of the transparent substrate where the image light enters,
A plurality of first cylindrical lenses for condensing image light are arranged in parallel, and on the exit surface, there is a distance wi between the first cylindrical lens and the focal length of the first cylindrical lens or more, and , a second cylindrical lens X'' for diffusing the image light at a predetermined angle is intermittently provided in a portion where the image light from the first cylindrical lens is condensed; A transmissive screen characterized by having black stripes applied to areas through which image light other than those provided does not pass through.