JPH04229299A - Writing board for dual use as screen for projection - Google Patents

Abstract

PURPOSE:To obtain a writing board capable of favorable writing and erasure and of dual us as a screen on which a legible and clear image is projected by means of an OHP or the like. CONSTITUTION:A writing board for dual use as a projecting screen provided with a reflection preventive layer having a glossiness of 70% or less, a haze value of 3.0% or more, and a center line average height (RA) of 1mum or less as a writing surface.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing and erasable writing board which can also be used as a screen for a projector such as an overhead projector (OHP).

0002

BACKGROUND OF THE INVENTION Conventionally, writing boards known as whiteboards have been used primarily for writing and erasing on the writing surface. Therefore, the whiteness and surface roughness of the writing surface are important qualities, and materials for the writing board surface are required to have high whiteness and low surface roughness. Examples of materials that satisfy such quality requirements include enamel and Teflon. In particular, enamel is inexpensive and has been used as an excellent material.

[0003] Also, for projection screens used in projectors for OHP and the like, matte cloth, film, etc. have been used to prevent images from becoming difficult to see due to surface shine caused by reflection.

0004

[Problem to be solved by the invention] Writing boards and OHP projectors such as those described above have been widely used in companies, schools, etc., and there is a desire to use the writing board as a projection screen. was there. However, as mentioned above, conventional writing boards as mentioned above used materials with high whiteness and low surface roughness as the writing surface material, so they had high gloss and were used as screens for projectors. In this case, there was a problem in that the reflection was too strong, making the image extremely difficult to see.

[0005]

[Means for Solving the Problems] The purpose of the present invention is to
To provide a writing board which is erasable and can also be used as a projection screen for OHP etc.

That is, the present invention is characterized in that an antireflection layer having a gloss level of 70% or less, a haze value of 3.0% or more, and a center line average roughness (Ra) of 1 μm or less is provided as a writing surface. The gist of this project is a writing board that doubles as a projection screen.

The present invention will be explained in detail below. Any type of writing board may be used, but if a transparent one is used as the anti-reflection layer, the surface on which the anti-reflection layer is provided will be used as a writing surface and a projection screen, so it should be white or white. It needs to be light in color. Therefore, a conventional so-called whiteboard may be used as is, or an enamel board, a plastic board, etc. may also be used. Of course, it may be a multi-layered material such as a plastic board pasted on a wooden board. Furthermore, even if it is in sheet form, it can be used because it can have a sufficient function as a writing board by attaching it to a wall or the like during use.

[0008] The antireflection layer provided on the writing surface of the writing board is
In order to be able to be written on and erased as well as used as a screen for a projector, the gloss level must be 70% or less, the haze value must be 3.0% or more, and the center line average roughness (Ra) must be 70% or less.
It is necessary that the particle diameter is 1 μm or less. This is because when the gloss level exceeds 70% and the haze value is below 3.0%, reflection becomes large and it becomes difficult to see, and when the center line average roughness (Ra) exceeds 1 μm, ink penetration occurs. This is because the data will be deleted and cannot be deleted.

Here, the glossiness is a value (%) measured with a glossmeter (manufactured by Suga Test Instruments Co., Ltd.), and the haze value (haze level) is a value measured using a haze computer (haze value measuring device) (manufactured by Suga Test Instruments Co., Ltd.). The center line average roughness (Ra) is the value (μm) measured with a Surfcom (surface roughness meter) (manufactured by Tokyo Seimitsu Co., Ltd.). be.

Various materials can be used for the antireflection layer, such as glass, plastic plates, and plastic films, as long as they have a surface condition that satisfies the above-mentioned physical properties. Alternatively, the film may be coated by spraying or the like. Furthermore, there is no limit to its thickness. When a transparent material is used as the antireflection layer, the transmittance is preferably 70% or more in order to effectively utilize the whiteness (light color) of the underlying surface.

[0011]

[Function] The antireflection layer of the projection screen/writing board according to the present invention has a gloss level related to diffuse reflection of light of 70% or less.
Since the haze value is set to 3.0% or more, diffused reflection is reduced, and even when used as a projection screen, there is no extra reflection and an easy-to-see image can be obtained. One way to lower the gloss and increase the haze value is to make the surface rougher, but if the roughness is too rough, ink will penetrate when writing with a marker, reducing erasing performance. Put it away. Therefore, the center line average roughness (Ra)
By setting the ink to 1 μm or less, when writing with a marker, the ink does not penetrate into the writing surface, and therefore writing can be made without fixation and can be erased.

[0014]

[Example] The substances shown in Table 1 were pasted on a white enamel board to form an antireflection layer, thereby creating a writing board that also served as a projection screen.

[0015]

[Table 1] Note: All glasses used had their surfaces etched with hydrofluoric acid.

[0016]

Effects of the Invention: Using the writing boards that double as projection screens obtained in Examples 1 to 4 and Comparative Examples 1 to 3 above, the erasability of marker handwriting and the ease of viewing images when projected with an OHP projector were improved. evaluated. The results are shown in Table 2.

Erasability: Commercially available OHP markers (black,
Write the letters using a commercially available OH
Erasing was performed using a P eraser (manufactured by Pentel Co., Ltd.), and the erasability was visually judged. Easy to see the image: Write on a transparent polypropylene sheet with an oil-based marker,
The visibility of the image when projected using a commercially available OHP projector was visually determined.

[0018]

[Table 2]

As is clear from Table 2, the writing board that also serves as a projection screen according to the present invention is a good writing board with excellent handwriting erasing performance, and at the same time, it can produce clear images on a projector such as an OHP projector. It is something that can be obtained.

Claims (1)

[Claims] [Claim 1] As a writing surface, the gloss level is 70% or less,
Haze value is 3.0% or more, center line average roughness (Ra) is 1
A writing board that doubles as a projection screen, characterized by having an anti-reflection layer of micrometer or less.