JPS5953194B2 - blackboard - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blackboard installed and used mainly in school education settings.

In current school education, in addition to the blackboard, which can be used as a display device for educational media such as letters that can be erased instantly, it also saves time writing on the board, and allows for free combinations of display contents and patterns, as well as the ability to save them. Projectors (particularly overhead projectors) are widely used because they have advantages such as being able to be used repeatedly.

In order to use such a blackboard and a projector together, conventionally, a screen dedicated to the projection by the projector was prepared separately from the blackboard, but in this case, it is necessary to install the screen in the classroom etc. Because it requires a considerable amount of space and the trouble of installing and storing screens depending on whether they are necessary or not, there is a strong tendency to avoid using them, and the educational effect of using them in conjunction with a blackboard is limited. The situation was such that it was not possible to fully achieve the objective of improvement.

The present invention was developed based on intensive research based on this point, and allows the blackboard itself to be used in common as a projector screen, thereby reliably achieving improved educational effects through the combined use of a projector and blackboard. It has a purpose in trying to make it happen.

The following is a problem that the inventors encountered when using a blackboard as a screen. In other words, a dark board surface is suitable for the blackboard to provide as much contrast as possible for characters written with white chalk. , research methods and results conducted to find out where is the optimal brightness range for a blackboard that satisfies two mutually contradictory requirements, such as the desire for a screen to be as bright as possible, such as white. Detailed information.

■ Investigation method Candidate brightness of the blackboard is 0.5 from 3.5 to 7.0.
A blackboard test condition (S condition) is when gray colored paper with 8 levels of brightness is prepared and a white Landolt pattern for visual acuity test with a brightness of 9 is printed on it using a silk screen. Overhead projector (hereinafter referred to as OHP).

) was defined as the screen test condition (S condition).

Observations were made with both eyes by 21 subjects with visual acuity of 0.7 or higher (average visual acuity of 1.1) from positions where the visual angle of the Landolt pattern was the same under both conditions (S condition 3.5 m, S condition 4.5 m). The ease of seeing the object was measured using a method similar to a visual acuity test.

However, since this is not a normal visual acuity test, the size of an object that a person with visual acuity X can clearly see is defined as visual acuity y', and this visual acuity value is used as an index of "easiness of seeing."

A correspondence table between visual acuity values and visual angles is shown in Table 1.

Therefore, visual acuity is 1 under any conditions such as distance, lighting, etc.
．． An object that can be seen accurately by a person with a score of 0 has a visual acuity value of 7 or higher, and the larger this value is, the easier it is to see.

The above procedure was performed under three lighting conditions, and changes in visual acuity in each case were observed.

The three lighting conditions are (I) high illuminance, (II) medium illuminance, and (
III) This is a low illuminance condition, which corresponds to conditions of ``bright,'' ``slightly bright,'' and ``slightly dark,'' which are psychologically spaced at approximately equal intervals.

In any case, if there is a brightness region in which visibility is above a certain level under both B and S conditions, it can be said that the area satisfies the practical range.

■ Survey results Table 2 and the figure show average data on the visual acuity side for each condition.

Under the S condition, visibility is very good when the illumination is bright, and there is almost no interaction with the brightness of the board surface.

Although this is not a very practical problem, when the illumination becomes dark, a brightness level of 6 or higher causes a rapid decline in visibility, so a brightness level of 6 or lower is suitable in terms of adding contrast and maintaining visibility.

In the S condition, when the OHP is brought close to the board surface and the screen brightness is increased, (S) the board surface is extremely easy to see regardless of the brightness, but when the OHP is projected away from the board surface (S) and the illumination is low, the screen is very visible. It shows variations depending on the surface.

Statistically, B (I) and B (II), B (II) and B (III), B (I) and B (III), and S
There was a significant difference between (I) and S (II) (P
>0.01 df=7).

■ Key points obtained from the survey results (1) When we converted the reactions of 21 subjects with an average visual acuity of 1.1 into visual acuity values to determine the ease of viewing the Landolt pattern, it was found that under OHP conditions, it was extremely High visibility is shown, and in the case of OHP, as long as the distance from the board surface is not too large, the brightness of the light source is sufficient, providing contrast, and visibility is not affected by the brightness of the board surface.

(2) Under the blackboard condition, visibility is a linear (or logarithmic) function of the brightness of the board surface (the darker the board surface is, the easier it is to see), and it acts independently of the lighting conditions.

(3) Based on the fact that an object with a visual acuity value of 7 can be seen under all conditions, a board surface with a brightness of 5.5 or less than 5 and a value of 4 or more (3.5 or more if you take into account the brightness increase due to chalk powder) It seems unsuitable for sharing a blackboard screen.

As is already clear from the above research results, in short, the blackboard according to the present invention fully fulfills the original function unique to blackboards, such as increasing the contrast with characters written with white chalk and improving visibility. Instead of black or moss green, which has traditionally been thought to be optimal for the dark board surface required above, the board surface has a brightness of 3.5 to 6.5, preferably 4.0 to 5.5. By keeping the color within the gray range of 5, it fully satisfies the performance requirements such as ease of viewing and good visibility for a blackboard, and is also extremely suitable for use as a projector screen regardless of lighting or board surface brightness. By achieving high visibility, it has become possible to practically use the blackboard as a screen, and as a result, it has become possible to truly improve the educational effect through the combined use of the blackboard and a projector.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the blackboard according to the present invention, and are diagrams showing changes in visibility depending on the brightness of the board surface and illumination conditions.

Claims (1)

[Claims] 1. A blackboard characterized by being colored gray with a brightness of the board surface ranging from 3.5 to 6.5, preferably from 4.0 to 5.5.