JPS6331991Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a compass used to draw an ellipse. By attaching it to both ends of the link, fixing the first car on the drawing surface and making the second car revolve around it,
This device is characterized in that an ellipse can be easily drawn with a writing instrument on a second link fixed to the second wheel.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In FIGS. 1 and 2, 1 is a first car, 2 is an idle car, 3 is a second car, and the second car 3 is A writing instrument attached to the second wheel 3 is made to make a planetary motion relative to the first wheel 1 to draw an ellipse.

The first wheel 1 has a substantially V-shaped fitting groove 4 formed on its outer periphery, and pins 6, 6, . A knob 7 is fixed to the upper end of the shaft 5, and a first link 8 is rotatably attached below the knob 7 on the shaft 5.

On the other hand, the second vehicle 3 has a radius ratio of 2 to that of the first vehicle 1.
A substantially V-shaped fitting groove 9 similar to that of the first wheel 1 is formed on the outer periphery, a knob 11 is provided at the upper end of a shaft 10 fixed at the center, and a caster is provided at the lower end. 13 is attached, the lower part of the knob 11 is rotatably attached to the first link 8, and a second link 14 for attaching a writing instrument is fixed to the lower part of the shaft 10. The second link 14 has a slit 15 cut in the axial direction, and a writing instrument support 16 is mounted on the second link so as to be slidable in the axial direction. As shown in FIG. 3, the support body 16 consists of a pair of opposing pieces 17a,
Holding pieces 17b, 17b are provided inside the slit 15 for holding the writing instrument 18, such as a pencil lead or a pen, inserted through the slit 15, and the opposing pieces 17a, 17a are provided in order to bring them into contact with each other. The screw 19 is inserted through it.
The screw 19 connects the writing instrument support 16 to the second link 1.
It is desirable to fix the writing instrument 18 on the writing instrument 18 and to make the clamping pieces 17b, 17b close to each other so that the writing instrument 18 can be clamped.

The first link 8 connecting the first and second wheels 1 and 3 includes a link piece 8a attached to the shaft 5 of the first wheel 1 and a link piece 8b attached to the shaft 10 of the second wheel 3. The connecting rod 20 is constructed by threading reverse screws connected to both ends of the connecting rod 20, respectively, so that the distance between the shafts 5 and 10 can be adjusted by rotating the connecting rod 20.

Furthermore, the above-mentioned idler wheel 2 includes first and second wheels 1 and 3.
A convex portion 22 is formed on the outer periphery of the idler wheel 2 to fit into the fitting grooves 4, 9 of the first and second wheels 1, 3, and a first convex portion 22 is formed on both sides of the idler wheel 2.
A friction surface 23b that contacts the friction surfaces 23a, 23a of the wheel 1 and the second wheel 3 is formed, and a shaft 24 that rotatably supports the idler wheel 2 is attached to a support rod 25, and both ends of the support rod 25 are It is supported so as to be movable left and right by hanging frames 26, 26 that are loosely fitted to the link pieces 8a, 8b.

The above-mentioned idler wheel 2 is provided with various diameters and is configured so that they can be replaced as necessary. That is, by rotating the connecting rod 20 in the first link 8, the shafts 5, 1 of the first and second wheels 1, 3 are connected.
If the distance between 0 and 0 is increased, the idler wheel 2 is made free and replaced with another idler wheel, then the connecting rod 20 is rotated to bring the new idler wheel into contact with the first and second wheels 1 and 3. good.

To draw an ellipse whose major and minor axes are 2A and 2B, respectively, using an ellipse compass of this construction, select an idler wheel with an appropriate diameter and adjust the fixed position of the writing implement 18 on the second link 14 to obtain the following: A = _r1 + _r2 B = _r1 - _{r2 r1} : distance between the axes of the first and second wheels 1 and 3, i.e., the revolution radius of the axis 10 of the second wheel 3, _r2 : distance from the axis 10 of the second wheel 3 to the writing implement 18, and then fix the axis of the first wheel 1 to the center of the ellipse to be drawn using the pins 6, 6, ..., and rotate the knob 11 of the second wheel 3 around the first wheel 1. For example, if the knob 11 of the second wheel 3 is rotated left around the axis 5 in Fig. 2, the first wheel 1 will rotate left.
As the idler wheel 2 rolls around the center of the ellipse, the second wheel 3 rotates clockwise on its axis while revolving counterclockwise, and an ellipse with major and minor axes 2A and 2B is drawn by the writing implement.

Based on FIG. 4, writing instrument 1 in the above operation
To briefly explain the locus of 8, in the figure, when the second wheel 3 rotates by θ around the center O of the first wheel 1, the writing point Q ₁ of the writing instrument 18 is - with respect to the first link 8. It rotates by 2θ, and the axis position and writing point of the second wheel 3 are displaced from P ₁ and Q ₁ to P ₂ and Q ₂ , respectively. Therefore, if the coordinates of the _Q2 point seen from O are (x, y), then it is expressed as x = (r ₁ + r ₂ ) cos θ y = (r ₁ − r ₂ ) sin θ, and from this, x ² /(r ₁ + r ₂ ) ² + y ² /(r ₁ − _{r 2} ) ² = 1, and the writing point is centered on O, and the long and short axes are (r ₁ + r ₂ ) and (r ₁ − r ₂ ), respectively. It is clear that it follows an elliptical trajectory.

As described above, according to the elliptical compass of the present invention, the following effects can be expected.

a Since the first wheel, idler wheel, and second wheel are driven using friction, there is no need for expensive gears whose teeth tend to wear out, making it possible to form a durable compass at low cost. can.

b By tightening the links, the frictional force between each car can be increased, so each car can be rotated reliably to draw an accurate ellipse.

c A V-shaped fitting groove is provided on the outer periphery of the first wheel and the second wheel, and a protrusion is provided on the outer periphery of the idler wheel, and each car is fitted with the fitting groove and the protrusion. Since the wheels are in contact with each other, each car is in very stable contact with each other, and there is no shaking of the cars or relative displacement in the vertical direction when rotating, and when the links are tightened to increase the frictional force. but,
The cars do not fall apart from each other.

[Brief explanation of the drawing]

Figure 1 is a side view of the elliptical compass of the present invention, Figure 2
The figure is a plan view, and Figure 3 is a sectional view taken along line A-A.
FIG. 4 is a diagram for explaining the principle. P... drawing surface, 1... first car, 2... idle car,
3... Second wheel, 4, 9... Fitting groove, 8... First link, 18... Writing instrument, 22... Convex portion, 23a,
23b...Friction surface.

Claims (1)

[Scope of utility model registration request] A first wheel and a second wheel with a radius ratio of 2:1 each having a substantially V-shaped fitting groove and a friction surface on the outer periphery are placed at both ends of the link whose length can be freely adjusted, and the outer periphery is placed between the two wheels. A idler wheel having a protrusion that fits into the fitting groove and a friction surface that contacts the friction surface is rotatably attached to the first wheel, and a fixed leg is provided on the first wheel to fix the idler wheel to the drawing surface. In addition, an elliptical compass characterized in that a writing instrument is attached to the second wheel so that the distance from the axis thereof can be adjusted.