JPH077993U - Circular ruler for board - Google Patents

Abstract

(57) [Abstract] [Purpose] When the present invention draws a circle on a blackboard or whiteboard at a school or a private school, the circle can be drawn with a single stroke without sticking the core on the blackboard, etc. And, anyone can draw many accurate concentric circles in a short time. [Structure] A large number of substantially circular cutout grooves 2 are concentrically formed in a disk body 1, and a large number of holes 3 are formed at regular intervals and in diameter, and with respect to a large number of the cutout grooves 2. The structure is such that the number 4 indicating an angle is depicted. Further, in order to make it convenient to carry, a hinge 6 is provided so that the disc body 1 can be folded.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circular ruler for boards used as teaching materials in schools and cram schools.

[0002]

[Prior art]

 Conventionally, when using circles to explain to students and children in schools and cram schools, blackboards and whiteboards use compasses for teaching materials and semi-circular protractors to create one or two sizes. Often draw different circles and teach based on them.

[0003]

[Problems to be solved by the device]

 However, when drawing a circle with the compass, the compass is large, so hold the base with one hand and rotate the compass with the other hand, but since the wrist does not rotate 360 degrees, hold it halfway and then rotate it. As it continues, the core of the compass tends to be misaligned, and it takes time and careful rotation to draw a precise circle. Especially when drawing a circle on the whiteboard, the surface of the whiteboard is very slippery, so it takes more time and labor. Therefore, there are many cases in which a circle is drawn with a free hand, but when explaining to a child or a student using a circle, if the circle is misaligned and distorted, the understanding of the child or student is likely to deteriorate, and the teacher will be careful. Currently, we are training to write circles. For this reason, there is a compass in which the tip is formed in a needle shape so that the core of the compass is not displaced. However, by sticking the tip on the blackboard, a solid circle can be drawn, but there was a drawback that the blackboard had holes. Incidentally, this compass could not be used because it could not be stabbed in a white board made of iron plate, and could only be used on a wooden blackboard.

When a circle is drawn using the protractor, only a semicircle of the size that uses the outer circumference can be drawn, and it is difficult to match the circles. Therefore, an accurate circle cannot be drawn well, and a circle of one size is drawn. I can only draw. It should be noted that even if an arcuate groove formed in the protractor is used to draw a small circle (see Fig. 3), it is the current situation that an accurate circle cannot be drawn well.

The present invention provides a circular ruler for a board that allows anyone to easily draw an accurate circle on a blackboard or whiteboard.

[0006]

[Means for Solving the Problems]

 The present invention has been made to solve the above problems, that is, a large number of substantially circular cutout grooves are concentrically formed in a disk body, and a large number of holes are formed at regular intervals and in diameter. A structure is provided in which holes are provided and a number or the like indicating an angle is drawn with respect to a large number of the cutout grooves. In addition, a hinge may be provided so that the disc body can be folded so that it can be easily carried.

[0007]

[Action]

 Next, the operation of the present invention will be described. First, when drawing two circles on a blackboard or whiteboard, place the product of the present invention in the position you want to draw in advance, and use a choke or a magic tool with the inside or outside of the appropriately sized cutout groove (2) as a reference. By moving along, a substantially circular shape is drawn. And since the joint portion (1a) of the substantially circular shape is not cut to form a perfect circular shape, it is easy for anyone to simply cut off the short cut point with a choke or a marker after separating the product of the present invention. You can draw an exact circle. Next, when drawing a circle of another size, place the product of the present invention at the position you want to draw in the same way as above, and use the inside or outside of the appropriately sized cutout groove (2) as a reference for a choke or magic. A substantially circular shape may be drawn by moving the same or the like along it, and then the circular shape in which only the joint portion (1a) is interrupted may be finished. In this case, since a large number of substantially circular cutout grooves (2) are concentrically provided in the product of the present invention, circles of different sizes can be easily drawn and the inside and outside of the cutout groove (2) can be easily drawn. Since the size of the circle is different, the circle can be drawn by freely selecting twice as many as the hollow groove (2). At this time, the size of the circle may be determined with reference to the number of the hole (3). When an angle is required, the angle number (4) drawn for the hollow groove (2) should be used as a guide.

The operation of the foldable product of the present invention shown in FIG. 2 will be described. Even if the widths of the pair of curved plates (12), (13), (14) are the same or different, they can be assembled by the hinge (6) and the shaft (7), so that they can be assembled in the above embodiment. In comparison, the width of the hollowed groove (2) can be freely widened. Therefore, if the width of the hollow groove (2) and the width of the curved plates (12), (13), (14) are made the same, it is possible to draw concentric circles that increase at equal intervals. This gives you more freedom in choosing the size and makes it easier for children and students to explain. Also, when carrying or putting away the product of the present invention, the disk body (1) is folded in half, which is convenient without being bulky.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. (1) is a circular disk made of synthetic resin or wooden. (2) is a large number of substantially circular cut-out grooves concentrically formed in the disc body (1), and the width of the cut-out grooves (2) is such that circles of different sizes can be drawn on the inner and outer side surfaces. Has a width of. Further, the circular shape of the hollowed groove (2) is interrupted only at the joint portion (1a). (3) is a large number of holes formed at regular intervals on the diameter of the disc body (1), and numbers near the holes (3) are drawn to serve as a scale. . (4) is a number in which the angle is drawn on the surface of the disc body (1) with respect to a large number of cutout grooves (2). (5) is a handle. When the magnet is attached to the back surface of the disc body (1) and the magnet is used for the white board, the handle (5) does not have to be attached.

FIG. 2 is a view showing another embodiment of the present invention, which has a structure in which it can be folded at the center of the disc body, as compared with the above embodiment. Explaining this, (1) is a foldable circular synthetic resin or wooden disc body, and the disc body (1) has a small shaft (7) described later passing through the center thereof. There are a disc (11) and a pair of semi-circular curved plates (12), (13), (14) of different sizes. (2 ') has a small disc (11) fixed to the center of the shaft (7), and a pair of curved plates (12), (13), (14) are hinged along the center (6). This is a substantially circular gap formed when the device is attached and assembled by being locked to the shaft (7), which corresponds to the hollow groove (2) in the above-mentioned embodiment. The numeral (4) indicates the angle on the surface of the semi-arcuate curved plates (12), (13), (14).

[0011]

[Effect of device]

 By having such a configuration, the present invention has the following effects.

Unlike the case of drawing a circle with a conventional compass, a circle can be drawn with a single stroke, so that there is no concern that the core will shift, and anyone can draw an accurate circle well in a short time.

Since the product of the present invention does not need to be punctured on a blackboard or the like, it is possible to easily draw a circle on the whiteboard while the blackboard has no holes.

It has been confirmed by the present inventor that an accurate circle can be drawn easily on both a blackboard and a whiteboard so that the child or the student can be better understood when the circle is explained to the child or the student. ing.

Since the training of writing a circle, which is conventionally required, is not required, anyone can immediately use it.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing another embodiment of the present invention.

FIG. 3 is a perspective view showing a conventional protractor.

[Explanation of symbols]

 1 Disc body 2 Drilled groove 3 Hole 4 Number 6 Hinge 7 Axis

Claims (3)

[Scope of utility model registration request] 1. A circular ruler for a board, wherein a large number of substantially circular cutout grooves (2) are concentrically formed in the disc body (1). 2. The disk body (1) is provided with a large number of holes (3) at regular intervals and in diameter, and a number () indicating an angle with respect to the large number of the cutout grooves (2). 4) A circular ruler for a board according to claim 1, wherein the circular ruler is drawn. 3. A hinge (6) so that the disc body (1) is split so that it can be folded and that they are connected.
A circular ruler for a board according to claim 1 or 2, further comprising: and a shaft (7).