Device for drawing circles, arcs of circles and measuring lengths on classroom boards or any other magnetic surface.

Abstract

Device for drawing circles or arcs of circles and measuring lengths on classroom boards or other magnetic surfaces. The invention relates to a device for accurately drawing circles or arcs of circles of selected radii on magnetic surfaces with one hand, and for measuring lengths. The device consists of a magnet (1) into which a peg (2) is screwed, a graduated tape (3) with a hole (4) at the 0 mark, the center of rotation of the tape (3) around the peg (2) at the center of the magnet (1), and a piece (5) that serves as a guide for the writing tool, which can be moved and locked by the user to select the radius of the circles or arcs to be drawn. After selecting the radius, the user inserts their writing tool into the most suitable hole of the two.The user rotates the ribbon (3), stretched around the magnet (1), while keeping the writing tool pressed against the board, to form the desired arc or circle. The graduations on the ribbon (3) also allow the user to measure lengths. The ribbon (3) has two sides graduated with different metric systems to meet the needs of a wide range of users. The device according to the invention is particularly intended for use with magnetic boards used by teachers or anyone with a magnetic surface.

Description

Title of the invention: Device for drawing circles, arcs of circles and measuring lengths on classroom boards or any other magnetic surface.

[0001] The present invention relates to a device for drawing circles, arcs of circles of chosen radii and measuring lengths on classroom charts or any other magnetic support, with the necessary and sufficient accuracy for their use and with great ease for the user.

[0002] Commonly used are articulated-arm compasses, which very often become misaligned during use due to the weight of the object and the verticality of the support, and which do not allow for the perfect drawing of a complete circle. Indeed, the user must manipulate the compass with both arms, requiring a decomposed movement, resulting in a loss of precision during drawing. Current systems also do not allow for direct measurement of lengths using a graduated scale.

[0003] Compasses with suction cup fixings have been manufactured to improve the fixing to the support, but the effectiveness is limited, the suction cups can slip and the articulated arm can become misaligned, and this does not solve the problem of drawing in several movements either.

[0004] The device according to the invention makes it possible to overcome these drawbacks. It is composed of: - a powerful magnet which has a thread to screw and unscrew a pin in its center; - a graduated ribbon in centimeters on one side, and in inches on the other, with a hole at the graduation 0 in which the magnet is inserted; - a piece that can slide and stop along the tape at the user's chosen position. It has three rectangular holes through which the tape passes. At each end of the piece, perpendicular to the tape, there is a circular hole of a different diameter aligned with the graduation desired by the user, serving as a guide for the writing tool.

[0005] The user begins by choosing the desired unit. To do this, they unscrew the pin located in the center of the magnet, select the end of the tape they wish to use and place it face up, insert the pin into the tape's eyelet, and then screw it back into the magnet to lock it in place. The user then selects the radius of the arc or circle to be drawn by positioning the movable piece at the chosen length. They lock the piece in place by passing the tape through the rectangular notch at the end of the piece. Once the piece is positioned, the user places the magnet on the point that serves as the center of the circle or arc. to trace. The user must now place their writing tool in the circular hole of the part with the most suitable diameter. They simply need to stretch the tape using their writing tool and rotate the writing tool around the magnet, which is resting on the board or magnetic surface, keeping the tape taut. In addition, the graduated tape allows the user to measure lengths shorter than the tape's length. The power of the magnet and the lightness of the various components allow the user to draw the circle or arc of a circle with one hand and to draw it continuously, without loss of precision, and thus to remedy the disadvantages of other existing systems.

[0006] The attached drawings illustrate the invention: [Fig.1] represents the magnet. [Fig.2] represents the graduated ribbon with a hole for an eyelet. [Fig.3] represents the piece alone, which will move on the ribbon (front view). [Fig.4] represents the piece alone, which will move along the ribbon (perspective view).

[0007] With reference to these drawings, the device includes a magnet (1) with sufficient strength to hold the entire object securely on the surface of the drawing board without moving during the pulling motion required to trace the circle or arc. The magnet (1) has a thread through which a peg (2) can be screwed into its center. This peg (2) is the pivot point of the ribbon (3). The ribbon (3) has an eyelet (4), allowing it to rotate around the peg (2). This eyelet (4) is positioned at the 0 mark on the ribbon (3). The ribbon (3) is graduated, allowing the user to select the radius of the circle that can be drawn. The ribbon (3) passes through the various rectangular holes in the part (5) so as to go underneath, then over, and finally underneath. The graduation of the ribbon (3) desired by the user will be that which appears on the visible face of the part (5) at the same level as the two circular holes.The user can easily move the part (5) along the graduation by keeping the ribbon (3) flexible and locking it in place by passing the ribbon (3) through the rectangular notch located after the first two rectangular holes. When the pull is applied to draw the circle or arc, the part (5) will lock at the desired graduation. To meet the needs of different users, the part (5) has two circular holes of different diameters, allowing the insertion of writing tools of various sizes. The centers of these two circular holes in the part (5) are aligned with the graduation area of ​​the ribbon (3) selected by the user, ensuring that the tip of the writing tool corresponds to the chosen radius of the circle or arc to be drawn.

[0008] By way of non-limiting example, the magnet (1) has a diameter of 20 mm, the ribbon (3) has a width of 1.5 cm and a length of 60 cm. The part (5) has two holes with diameters of 8 mm and 12 mm respectively.

[0009] The device according to the invention is particularly intended for tracing circles, arcs of circles and measuring lengths for magnetic boards especially used in classrooms by teachers.

Claims

Demands

1. "Device for drawing circles, arcs of circles of chosen radii and measuring lengths, in centimeters or inches, on classroom boards or other magnetic surfaces, characterized in that it comprises a magnet (1) having in its center a thread for screwing and unscrewing a peg (2), which will determine the center of the arc or circle to be drawn, a graduated ribbon (3) with a hole in its eyelet (4) at its graduation point 0, the magnet (1) being inserted in said eyelet (4) so ​​as to be able to rotate around the peg (2), and a movable part (5) mounted to slide on the ribbon (3) and so as to be able to be locked along said ribbon at the length desired by the user, the movable part (5) having two rectangular holes for the passage of the ribbon, a rectangular notch, in which the ribbon passes to lock the sliding at the chosen length, which appears visible,between the two rectangular holes and two circular holes of different diameters located at each end of the piece orthogonally to the ribbon (3), the circular holes being intended to serve as guides for writing tools.

2. Device according to claim 1 characterized in that the magnet (1) is of sufficient power to resist the pull to tension the ribbon (3) without the magnet (1) being displaced.

3. Device according to claim 1 characterized in that the ribbon (3) has a graduation in centimeters on one face and in inches on the other face, the graduations 0 being aligned.

4. Device according to claim 1 characterized in that the part (5) has two rectangular holes through which the ribbon (3) passes first under the part (5), then over it and finally under it and in the rectangular notch to lock the part (5) on the ribbon (3) at the chosen length which appears face visible between the two rectangular holes.

5. Device according to claim 1 characterized in that the graduation of the tape (3) allows the user to measure lengths less than its length.

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