JPS59223419A - Transmission type screen - Google Patents

Abstract

PURPOSE:To improve the contrast of a video and to obtain an easily-produced economical screen by forming a long groove along the dark stripe part on an observing surface, charging the groove with fine powder which is a light absorving body, and adhering the fine powder at the upper surface part. CONSTITUTION:Light is projected from a video projector to the projection surface of a transmission type screen 1 and the projection surface 2 is constituted of a wrenchcular surface consisting of many long lenses 22 expanding their longitudinal axes in the vertical direction. In order to improve the contrast of a video, the dark stripes 3b are used as a light absorbing/shielding part. Namely, long grooves 31 are formed along the dark stripe 3b parts on the observing surface 3 of the transmission type screen 1 and charged with fine powder 32. Thus, the light absorbing/shielding part with fixed and uniform width can be formed on fixed position precisely, so that the complex process can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission screen, and more particularly to an improvement in a transmission screen provided with light-absorbing stripes to improve image contrast.

Various types of transmissive screens have been proposed for use in video screens of video projection televisions, and some of them have been put into practical use in U-J.

Video projection television is a device that projects both large images onto its video screen.

It is used by kings for the purpose of allowing a large number of viewers to observe at once. In order to enable viewing by a wide range of viewers, a video screen with a wide viewing angle must be used, and a lenticular screen is preferably used for this 1 degree angle.

A ticular screen is a cylindrical screen in which a large number of elongated lenses, such as cylindrical lenses, are arranged on at least one side, with their longitudinal axes almost parallel. The lens refracts and focuses the light at a specific angle 1r from the observation side.
It is designed to diffuse and emit light within a radius of σ. As shown in C1σ, a lenticular screen is made up of a large number of long and narrow lenses arranged, so on the front side of the lenticular screen there are two areas: a bright, thin part through which light passes through due to the refraction and focusing action of the long and narrow lenses, and a long, thin part through which light does not pass. A dark area 2 appears.

That is, on the front surface of the lenticular screen, a large number of parallel bright stripes and dark stripes are generated by the transmitted light. Generally speaking, in a transmission screen having one surface having a lens effect, there are bright areas through which light passes and dark areas through which light does not pass, on the viewing side.

It is preferable that the video projection screen 7 can also be used in a so-called bright room where there is quite bright outside light. However, when external light hits the image area of a video projection screen, it brightens (illuminates) the image area that displays dark areas such as black, reducing the contrast of the image.

What is the image contrast of a general video projection screen?

Defined by

Furthermore, HMAX: Brightness of the bright part of the image BM engineering N:
Brightness BI of dark areas of the image: Reflected brightness of external light in bright areas B,: Reflected brightness of external light in dark areas.

In a dark room with no outside light* B1. +hx/BMIN ratio "4. Contrast improves by increasing it, but in a bright room affected by external light, the reflected brightness of external light (B, * 82
) must be taken into account.

In other words, the trick to increasing the contrast of the image on the video projection screen itself is to increase the reflected brightness of external light on both sides (
The second is to suppress Btr By as much as possible. In other words, the amount of external light that passes into the inside of the video projection screen is increased (thus increasing the amount of external light that passes through the video projection screen, thereby giving the video projection screen the ability to absorb external light. Specifically, light-absorbing substances are scattered on the screen base material). Another method is to provide a light-absorbing portion on the surface of the screen.

For example, in Japanese Patent Publication No. 52-46693.

It has been proposed to increase the contrast by providing a light-shielding stripe portion on the opposite side of a transmissive video projection screen in which a lenticule consisting of a large number of cylindrical lenses is installed on one side, through which no light passes. In other words, the video projection screen disclosed in Japanese Patent Publication No. 52-46693 is a lenticular screen with a photoresist film provided on the opposite side of the surface on which the lenticules are provided, and this film is exposed, developed, and dried to prevent the light on the opposite side. A stripe pattern of a photoresist film is formed with the photoresist film remaining only in the areas where the light does not pass through, and oil-based ink is adhered onto this stripe pattern by offset printing or the like to form a light-shielding area.

However, printing oil-based ink on a striped pattern as described above requires a fairly sophisticated printing technology and requires complicated steps. This is because the 7 drive of the stripe pattern is very fine (and it is necessary to accurately align the ink application. Also, the process of exposing, developing, and drying the photoresist film is omitted. The production of Video Glossy Exposition/Screen = 7 requires work in a dark room, which complicates the purification process. Therefore, manufacturing costs inevitably increase.

A method of printing or painting directly on the portions of the video projection screen through which light does not pass could be considered, but this tends to result in uneven printing (and as mentioned above, it is difficult to paint in a narrow and uniform width).

In view of this situation, instead of forming the original absorption layer by printing, the present applicant created a transmissive layer in which grooves were provided along the areas through which light did not pass, and threads serving as light absorbers were placed in the grooves. The present invention has already proposed a transmission type screen screen (4? Application No. 57-234,...! No. 09).Similar to this proposal, the present invention is a transmission type screen that has excellent performance, is easy to manufacture, and is suitable for inexpensive video projection. The purpose is to provide a screen.

That is, the gist of the present invention is to provide a transmission screen having a projection surface and an observation surface.

At least one of the projection surface and the observation surface is formed to have a lens effect, and the light projected onto the projection surface is divided into a large number of bright stripes through which light passes through the observation surface, and where light does not pass through the observation surface. It is configured such that a dark stripe portion is defined.

A transmission device characterized in that elongated grooves are formed along the dark stripe portion of the observation surface, and fine powder serving as a light absorber is arranged in these elongated grooves and is fixed at least on the upper surface. On the type screen.

The transmission screen of the present invention is made of acrylic resin.

Vinyl chloride resin, polycarbonate resin, mine ■
Manufactured by extrusion molding, hot pressing, or injection molding of materials such as fin resin and styrene resin. Therefore, the large number of elongated grooves formed on the observation surface of the transmission screen described above can be easily formed at the same time as the lens action surface.

The invention will be explained in more detail below in the form of an exemplary embodiment and with reference to the accompanying drawings, in which: FIG.

FIG. 1 schematically shows a video projection device, in which projection light is projected from a video projector (P) onto a projection surface (2) of a transmissive screen (IN') according to the present invention. The projection surface (2) has a longitudinal axis extending in the vertical direction.It is a lenticular surface with a large number of #l-long holes (21°C).The projection light is refracted and focused by the elongated lens. The light fin is emitted from the observation surface (3) in a horizontal direction in a uniformly distributed manner over a predetermined angle range.
), on the observation surface (3), the original passing bright stripe portion (3a) and the original dark stripe portion (3b) that are parallel to each other are alternately parallel to each other in the vertical direction. be done.

In order to increase the contrast of the image, the dark stripe portion (3b) is used as a light absorbing and shielding portion.In this embodiment, as shown in detail in FIG. The dark stripe (3) on the observation surface (3)
In the part b), elongated grooves (3υ) are provided along this, and fine powder (32 mm) is inserted and placed in these elongated grooves (3υ). This is the fixed layer of the part.

The fine powder (32) used in the present invention is not limited to 1% as long as it has a single absorption capacity, but a fine powder obtained by pulverizing a black metal powder such as a black pigment, ferrite, or iron oxide, a colored synthetic resin, etc. is used, Among these, carb/ is particularly preferred. In this way, the fine powder (32) as a light absorber can be arranged and fixed in the elongated groove (31) of the observation surface (3) of the transmission screen (17) in a simple manner to accurately place it in a fixed and uniform position. It is possible to provide a light-absorbing and light-blocking part in the same width. Also, since there is no need to print and paint the light-absorbing and focused part unlike in conventional transmission screens, the complicated process associated with this can be omitted. It is possible to fix the upper surface of this fine powder (32) by attaching a solidifying liquid 9/J material such as adhesive or paint to this part to provide a fixing JV1 (33). , a thin transparent fixing # (33) may be provided on the entire surface as shown in FIG. The reason why the fine powder (32) is fixed at the upper surface is that there is an air layer in the fine powder (32).

This is particularly effective when using a lenticular lens body having a total reflection surface, which will be described later.

Figures 3 to 5 show an elongated lens body (3) of a different shape on the observation surface (3) of a transmission type screen (1).

This is an example in which a lenticule in which a plurality of (35) are arranged is provided. These lens bodies (34) and (35) have 9 individual I/
The sloped surfaces on both sides of the lens are total reflection surfaces, and no ℃ radiation is emitted from these surfaces, forming a dark stripe.

Regarding a transmission type screen provided with a lenticule having such a lens body (34), (,:'r), see Japanese Patent Application No. 1983 511:Y4 and Japanese Patent Application No. 1983, filed by the same applicant.
-91896, Japanese Patent Application No. 56-212584, and Japanese Patent Application No. 56-29178.

The melting process of these lens bodies (34) and (35) is not directly related to the present invention and will not be described in detail in Japanese Patent Application No. 57-59389.

7 and the transmission type X"I in FIGS. 4 and 5 above
J -yvcra+ Fresnel lens (
22) This Fresnel lens (22)
) refracts the source incident on the projection surface (2) into parallel light.

Since it has the effect of focusing light on a predetermined location on the observation side, it is particularly useful for maintaining brightness around the screen and making the screen uniform in brightness. For this reason, the embodiment shown in FIG. 6 is an example in which a separate Fresnel lens sheet (4) is arranged on the projection side of the screen shown in FIG.

As described above, the present invention is manufactured using a synthetic resin material such as acrylic resin, but the base material that becomes the screen is made of, for example, Sin, A7? (OH),, AdtO3゜Ca
One type of diffusing agent such as C01, BaSO4, 'rto, etc. or 2f! It is effective to further improve the diffusion performance by adding i or more. It is also effective to adjust the color tone of the screen by adding a coloring agent in combination with the diffusing agent or alone. Sarashiko.

As a means of improving the diffusion performance, it is also preferable to form a finely uneven surface on the projection surface and/or observation surface of the screen 7. 71 (j-The method of putting the fine powder (32), which is a ternary absorber, into the groove at 3υ is to spray the dry fine powder (32) or pour it over the top to remove unnecessary parts. This can be easily done by wiping off the fine powder (32) with a cloth or flexible rubber.Adhesives and paints are used as liquid substances for fixing, as mentioned above. Examples of the liquid substance include polyvinyl alcohol, acrylic, vinyl acetate, and vinyl acetate.

Example A transmission screen equipped with lenticules of the type shown in Fig. 4 was heated in a heated press (temperature 180°C) using an acrylic resin plate (thickness: 3mm) to which SIO with an average particle size of 4μ was added at a concentration of 23mm. ℃, pressure A, 01y/cm'). The lenticular lens structure of this transmission screen is shown in detail in FIG.

Then, carbon black having a particle size of 1 μm or less was sprinkled over the viewing surface of the transmission screen, and after filling the grooves with carbon black, unnecessary portions were removed with a damp cloth. Then, a polyvinyl alcohol glue "Fixatib" manufactured by Holbein Industries was spray applied to the entire surface to fix the upper surface of the carbon black.

The product of the present invention (A) was prepared by the above method, but for comparison, a sample (B) without carbon black fixed was also prepared at the same time, and the transmission characteristics were first measured, and the diffusion state in the horizontal direction was as shown in Figure 9. Met. Note that the characteristic values at this time were as shown in Table 1.

Table 1 Here, 00 is the maximum gain, the gain when the angle is 0°, and α(Th is the gain when this gain is &
The β value is the angle when the angle becomes hK. Note that the angle when the angle becomes 11 (G) is the brightness ζ when illuminating with a unit illuminance.

As is clear from Table 1 and FIG. 9, the transmission screen (A) of the present invention has a higher G than the comparative product (B).
Although the o value, α value, and β value were slightly lowered, the result was good, with uniform diffusion over a wide range.

Also, using the contrast testing apparatus schematically illustrated in FIG. 8, from a direction of 45 degrees to the normal to the sample,
External light was applied from a + source (La) so that the illuminance on the observation surface of the transmission screen was 5001x, and the contrast ratio was determined. When comparing this with the contrast ratio when there is no external light, the ratio is calculated to determine how much the contrast ratio has decreased when there is external light compared to the contrast ratio when there is no external light, and this is defined as the reduction rate. did.

That is, the contrast when there is no external light is CO, and the contrast when there is external light is C8, and the rate of decrease in contrast due to external light was calculated using the following equation.

At this time, set the value of C9 when there is no external light to 45,
The brightness ratio between Bmax and Bmin was adjusted. Ko
11 The rate of decrease in trust varies depending on the value of C0, so it is not a value specific to that sample.

If C0 is kept constant, it can be said to be a value that can be used as a guide for determining the influence of external light. Therefore, this rate of decline is large;
The closer it is to 1, the less the contrast decreases due to external light. This rate of decrease was calculated every 10 degrees from the external light side and is shown in FIG. From the same figure, compared to the case (B) without carbon black, the provision of the carbon black absorbing layer significantly improves the contrast reduction rate as shown in (A).

The present invention has been described above in detail in the form of examples.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims.

[Brief explanation of the drawing]

1 is a diagram schematically illustrating a video projector device in a perspective view, FIG. 2 is a partial cross-sectional view of the transmission screen used in FIG. 1, and FIGS. 3 to 5 show other embodiments. 6 is a partial perspective view showing still another embodiment, and FIG. 7 is a partial sectional view showing a sample of a transparent screen molded to demonstrate the effects of the present invention. , FIG. 8 is a schematic diagram of a contrast testing device used to demonstrate the effects of the present invention, FIG. 9 and FIG.
FIG. 0 is a diagram illustrating test results showing the effects of the present invention. 1...Transmissive screen 2...Projection surface 3...Observation surface 21, 33.35.36...Lens body 31...
...Elongated groove 32...Fine powder P--Projector curtain l concave #2. ! J Stem 3 Concave Qin 4 (2) U5 Leap book 6 Book 7 Figure also 8 Figure 1 □ O・l -Damn- 1-□ 0 Binnie Anne 7° Shire (Dan

Claims (1)

[Scope of Claims] 1. A transmission type screen having a projection surface and an observation surface, the projection surface and the observation surface are formed so that the projection surface and the observation surface are The source projected onto the observation surface is configured such that a large number of bright stripe portions through which light passes and dark stripe portions through which light does not pass are defined on the observation surface, and along the dark stripe portions of the observation surface. Elongated grooves are formed, and fine powder serving as a light absorber is arranged in these elongated grooves, and this also covers at least the upper surface υ.
A transparent screen characterized by being fixed at the 2' portion, and a lenticular lens body is provided to have a lens function on the projection surface. Transmissive screen according to item 1. 3. The transmission type screen according to claim 1 or 2, characterized in that the viewing surface is provided with a lenticular lens body having a lens function. 4. A 7-lens lens is provided on the projection surface. 5. A transmission screen according to claim 1 or 3, characterized in that the screen has a diffusion agent added to the screen base material. The transmission type screen according to item 1, item 2, item 3, or item 4. Claims characterized in that a finely uneven surface is formed on a 6° projection plane and/or observation plane. Transmission type screen according to item 1, 2, 3, 4 or 5.