WO2006111854A2

WO2006111854A2 - Drawing instrument

Info

Publication number: WO2006111854A2
Application number: PCT/IB2006/001090
Authority: WO
Inventors: Hossein Arvin
Original assignee: Hossein Arvin
Priority date: 2005-04-21
Filing date: 2006-04-10
Publication date: 2006-10-26
Also published as: WO2006111854A3

Abstract

A drawing instrument capable of drawing circles and ellipses on a working surface, said drawing instrument having a depending stationary arm and a depending revolving ami mounted on a shell, said shell having a mid point that is aligned with a longitudinal vertical axis of the drawing instrument, the revolving arm joined by a pin to the shell from the mid-point of the shell, the shell is rotate able, secured and centered over a thrust bearing wherein a top end of the stationary arm and a top end of the revolving arm scribe a circle or ellipse in an imaginary plane above and parallel to the working surface and which is transferred by the remote end of the revolving arm to the working plane to draw a circle or ellipse, said circle or ellipse drawn on the working surface is proportional to the circle or ellipse formed by movement of the top end of the stationary arm and top end of the revolving arm.

Description

TITLE: DRAWING INSTRUMENT

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

This invention relates to a drawing instrument. In particular the present invention provides apparatus for drawing circles and ellipses for drafting and also drawing on art works, crafts or similar activities on varieties of the materials.

DESCRIPTION OF THE PRIOR ART

Traditionally drawing instruments capable of drawing either a circle or an ellipse are known. All of these known devices suffer serious drawbacks. For example US Patent 6,308,426 is directed to an instrument to draw only ellipses. It is incapable of drawing small ellipses due to the location of its base. It is also not practical to be used as a handheld device due to its form and functions and all components are exposed. US Patent 5,870,830 requires high skills and mathematic knowledge to operate the device. It is incapable of drawing small circles due to its size and its shape. It requires more than one person to operate with accuracy. US Patent

5,546,664 is directed to a device that only draws ellipses. The components that permit adjustments for drawing different sizes of ellipses are exposed. The ellipsograph shown in US Patent 5,056,230 is not practical for use as a handheld device. Similarly the device shown in US Patent 4,688,331 is not practical to be used as a handheld device and components that permit adjustments for drawing different sizes of ellipses are exposed and require a skilled person to operate. The device shown in US Patent 4,182,043 is impractical to be used as handheld device due to its functions and is not capable of drawing circles. The device shown in US Patent 4,150,487 is impractical to be used as handheld device and is not capable of drawing circles. The device shown in US Patent 4,010,546 has similar drawbacks; it requires skill to operate and is impractical to be used as handheld device.

There is a need for a drawing instrument capable of drawing any size circles and ellipses that does not have complicated methods of adjustments that require high skill level to operate, can easily be carried and used as a handheld device, protects the components that permit adjustments for drawing different sizes of ellipses from exposure, permits the user to view the working plane properly to execute the drawing operation, and operable by one hand.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a drawing instrument capable of drawing circles and ellipses on a working surface of different sizes.

It is a further object of the invention to provide a drawing instrument capable of drawing circles and ellipses that is simple to adjustment for different sizes.

It is a further object of the invention to provide a drawing instrument capable of drawing circles and ellipses used as a handheld device operable by one hand.

It is a further object of the invention to provide a drawing instrument capable of drawing circles and ellipses where the components that permit adjustments for drawing different sizes of ellipses are protected from exposure.

It is a further object of the invention to provide a drawing instrument capable of drawing circles and ellipses that permits the user to view the working plane properly to execute the drawing operation. It is a further object of the invention, where the method of adjustment used in the instrument and the transformation of the drawn shape can be employed in variety of the automated instruments. It is a further object of the invention that its form and movements instruct the user visually and reveal the transition of the circle drawing device to an ellipse drawing device simultaneously providing an educational experience for a user.

Thus in accordance with the present invention there is provided a drawing instrument capable of drawing circles and ellipses on a working surface, said drawing instrument having a depending stationary arm and a depending revolving arm mounted on a shell, said shell having a mid point that is aligned with a longitudinal vertical axis of the drawing instrument, the revolving arm joined by a pin to the shell from the mid-point of the shell, the shell is rotate able, secured and centered over a thrust bearing wherein a top end of the stationary arm and a top end of the revolving arm scribe a circle or ellipse in an imaginary plane above and parallel to the working surface and which is transferred by the remote end of the revolving arm to the working plane to draw a circle or ellipse, said circle or ellipse drawn on the working surface is proportional to the circle or ellipse formed by movement of the top end of the stationary arm and top end of the revolving arm.

In another embodiment the present invention provides a drawing instrument capable of drawing circles and ellipses on a working surface, said drawing instrument having: a housing assembly having a top portion and a bottom portion, wherein the top portion is swivel ably engaged to the bottom portion; a mid-point of the top portion of the housing assembly aligned with a central longitudinal axis for the drawing instrument; to arms, first aπn and second arm.) a stationary arm capable of splitting in to first and second arms having an upper end and a bottom end, the upper end of said first and second arms containing within said housing assembly and the first and second arms extending through the bottom portion of the housing assembly and said first and second arms pivotally connected adjacent their upper ends; upstanding posts mounted on the upper end of said first and second arms, a writing arm hinged and secured to the mid-point of the top portion of the housing assembly and adapted to move circumferentially around the first and second arms; and a guide thread assembly mounted within the housing assembly, said guide thread assembly including: a thread pointer having its apex perform as the third tip of the ellipse structure, a guide thread of adjustable length, an adjustment assembly means for adjusting the length of the guide thread and means for holding and retaining any excess guide thread; and a support assembly means for enabling the guide thread assembly to move laterally in relation to the longitudinal axis of the drawing instrument and for maintaining the first and second arm's tips in the same plane as the thread pointer apex. In yet another embodiment the present invention provides a hand held drawing instrument capable of drawing different sizes circles and ellipses, said drawing instrument having a depending stationary arm and a depending revolving arm mounted on a shell, said shell having a mid point that is aligned with a longitudinal vertical axis of the drawing instrument, the revolving arm joined by a pin to the shell from the mid-point of the shell, the shell is rotate able, secured and centered over a thrust bearing preferably the shell is made of a transparent material for visibility, said revolving arm adapted to follow the circumference of a circular ring, said circular ring is tilt able and mounted within the shell, means to adjust the size of the circular ring and means to adjust the angle of the ring. The drawing instruments of the present invention are capable of drawing any size circle and ellipse limited only to the practical size of the instrument. The drawing instruments resemble the common compass and require simple adjustments and in a preferred embodiment its form instructs the user visually and reveals the transition of the circle drawing device to an ellipse drawing device simultaneously providing an educational experience for a user. Also the form of the apparatus allows the components to remain concealed and considered as a hand held device. It could be operated only by one hand. Since the components are above the working plane, it provides a clear view for the user. Further features of the invention will be described or will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more clearly understood, the preferred embodiment thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of how to draw a circle and ellipse;

Figure 2 is a schematic representation of adjustable arm equipped by a flexible cord;

Figure 3 is a perspective view of an embodiment a drawing instrument capable of drawing circles and ellipses according to the present invention having a pair of adjustable arms that define the focal point(s) around which the circle or ellipse is drawn and a revolving arm..

Figure 4 is a perspective view of the drawing instrument of Figure 3 with the housing broken away to show the components that permit adjustment of the revolving arm relative to the pair of adjustable arms.

Figure 5 is another perspective view of the drawing instrument of Figure 4 showing just the track system that allows the revolving arm to rotate around the tips of the pair of adjustable arms;

Figure 6 is another perspective view of the drawing instrument of Figure 5 showing just the means to rotate the revolving arm;

Figure 7 is a perspective view of the pair of adjustable arms of the drawing instrument of Figure 3, in a spaced apart arrangement; Figure 8 is perspective view one of the pair of adjustable anus of Figure 7; Figure 9 is an enlarged elevation view of the components responsible for self- adjusting the length of the arms of the drawing instrument of Figure 4 and provides a method of finding the proper radiuses for creating slots in the shape of an arc using a panel with arc shaped slots, sockets with vertical slots, and posts equipped with pins attached from the center;

Figure 10 is a perspective view of another embodiment of a drawing instrument capable of drawing only circles according to the present invention with the housing broken away to show an alternative means for adjusting the distance of the revolving arm with the stationary arm and its vertical axis;

Figure 11 is a perspective view of another embodiment of a drawing instrument capable of drawing circles and ellipses according to the present invention with the housing broken away to show a third alternative means to rotate the revolving arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to draw a circle, (as illustrated in Figure 1), a marking point C is rotated around a fixed focal point A at a constant distance B (radius). The size of the circle is determined by the distance B the marking point C is from the focal point A. In order to draw an ellipse, as illustrated in Figure 2, a marking point C is rotated about a pair of spaced apart focal points A, B. As the marking point C is rotated about the pair of spaced apart focal points, the sum of the distances from each of the focal points is constant. The size and shape of the ellipse is determined by the distance between the two focal points A and B and the sum of the distances the marking point C is from each of the focal points A, B. Manually drawing an ellipse is tedious unless a template is used. However templates are seldom provided in a large variety of sizes.

Referring to Figures 3 and 4, an embodiment of a drawing instrument capable of drawing circles and ellipses of various sizes according to the present invention is generally indicated at 1. The drawing instrument 1 has a housing assembly 2having a top portion 3 and a bottom portion 4 where the top portion 3 is swivel able and engaged to the bottom portion 4. A knob 5 is centrally located on the top portion 3 of the housing assembly 2 for holding the drawing instrument and to define a central longitudinal axis for the drawing instrument 1. A stationary arm capable of dividing into first and second arms 6, 7 extends through the bottom portion 4 of the housing assembly. Each of the first and second arms 6,7 as shown in Figures 7 and 8 have an elongated depending leg portion 8,9 having a top end 10,11 bottom end 12,13 and facing side edges 14,15. A hub portion 16, 17 is connected to the top end 10, 11 of each of the leg portions 8, 9. Hub portions 16, 17 include a ring section 18, 19 ( see Figure 7) an offset upstanding socket section 20,21 having a top side 22,23, bottom side 24,25 and opposite vertical sides 26,27 and 28,29 respectively. An upstanding post 30, 31 is inserted into a cavity 32, 33 in the socket section 20, 21 that opens onto the top surface 22, 23 of the socket section 20,21. A vertical slot 90, 91 in the vertical sides 26, 27 and 28, 29 of the socket sections 20,21 communicates with the cavity 32, 33 in the socket section 20, 21. A pin 34, 35 is inserted into the slot 32, 33 and through the post 30, 31. The pin/slot arrangement permits the post 30, 31 to move vertically within the cavity 32, 33. A pair of springs 92, 93 pulls the two hub portions 16, 17 toward each other (see Figure 7). The first and second arms 6, 7 are self-adjustable in length and keep themselves in a certain plane. This self adjusting system could be applied to both ends 30, 31 and 13, 12. Two sets of slots, one in straight, vertical shape 90, 91 and one arc shaped communicate and lift the post 30, 31 in desired height or position. The calculation of these two radiuses for creating the arc shaped slots comes from the line which makes the shortest distance between the center of the pin and the imaginary plane of the drawing at the top while the arms are in a resting position and their tips form a single tip, this line is called R. One of the radius which is larger R2 =R + radius of the pin itself Rl + the tolerance and the other radius is R3= R- Rl -the tolerance and center of the arc is the point where the plane and the line meet. With the ring sections 18, 19 of the first and second arms 6, 7 aligned an axel 36 is inserted through the ring sections 18, 19 to join the first and second arm 6,7 so that they can pivot around axle 36. The depending bar 37 is connected to the center point of axel 36 perpendicular to the longitudinal axis of the axle 36. An adjusting knob 38 reciprocates along the bar 37 to pivot the first and second arms 6, 7 around axle 36. The adjusting knob 38 is connected to one end 39 of a pair of spacer bars 40, 41. The other end 42 of spacer bar 40 is attached to the first arm 6 at point 43. Similarly the other end 44 of spacer bar 41 is attached to the second arm 7 at point 45. As adjusting knob 38 is moved up bar 37, spacer bars 40,41 cause the first and second arms 6,7 to pivot around axle 36 and the bottom ends 12, 13 of first and second arms 6,7 to be spaced apart. As adjusting knob 38 is moved down bar 37, spacer bars 40, 41 cause the first and second arms 6, 7 to pivot around axle 36 until the bottom ends 12, 13 of first and second arms 6, 7 are co-terminus. Notches 46,47 in the facing side edges 14,15 of first and second arms 6,7 permit the elongated depending leg portion 8,9 of arms 6,7 to pivot around axle 36 until the bottom ends 12, 13 of first and second arms 6,7 are co-terminus. The bottom ends 12, 13 of first and second arms 6, 7 are co- terminus when the drawing instrument 1 is used to draw a circle. The bottom ends 12, 13 of first and second arms 6, 7 are spaced apart when the drawing instrument 1 is used to draw an ellipse. A thrust bearing 48 is centrally located and secured on the ends of axle

36. The center axis of thrust bearing 48 (Figure 4) is located at the mid-point and perpendicular to the longitudinal axis of axle 36. The bottom portion 4 of housing 2 is secured and centered on thrust bearing 48.

In order to scribe either a circle or an ellipse, drawing instrument 1 is provided with a writing arm 49 hinged and attached to the inside surface 56 of the top portion 3 of housing 2 below the longitudinal axis of knob 5. The writing arm 49 is adapted to revolve peripherally around the first and second arms 6, 7. The writing arm 49 preferably has a depending leg portion 50 with a top surface 51 and bottom end 52. The bottom end 52 is equipped with a marking device 53 such as lead, ink etc. Depending leg portion 50 preferably has a first top section 54 and a second bottom section 55 that can be moved longitudinally relative to each other to extend the length of the depending leg portion 50.

The writing arm 49 is connected to the inside surface 56 of the top portion 3 of housing 2 below the longitudinal axis of knob 5 by a pivot pin 57 having one end 58 pivotally connected to the inside surface 56 of the top portion 3 of housing 2 below the longitudinal axis of knob 5 and the other end 59 connected to post 60 which is attached to the top surface 51 of depending leg portion 50. This pivot pin 57 is the axel on which the writing arm 49 increases and decreases its distance from the focal point, or points. These arrangements provide a symmetric position relative to the tips and perpendicular position to the center of the apparatus for all the parts that are secured over the axel 36 including the stationary arms themselves. Therefore the knob for handling and turning the apparatus, the pin that connect the revolving arm, the shell, the thrust bearing, the stationary arm's pin axel 36, the adjusting knob and the bar all are centered. The post 60 connects the top surface 51 of the depending leg portion 50 to the pivot pin 57.

A guide thread assembly, generally indicated at 61, is provided within the top portion 3 of housing 2. The guide thread assembly 61 includes a guide thread 62 of adjustable length slide ably engaged to the writing arm 49 and to the upstanding post 30,31 on the upper end of the first and second arms 6,7. An adjustment assembly means for adjusting the length of the guide thread 62 and means for holding the excess guide thread is provided. In addition there is a support assembly to enable the guide thread assembly to move laterally in relation to the central axis of the drawing instrument. In the embodiment illustrated as best shown in Figures 4-5, a thread - feeding guide 63 is pivoted to the writing arm 49 and is fixed to move only in a fixed horizontal plane. This fixed horizontal plane is above and parallel to the working plane on which the circle or ellipse is to drawn. In the embodiment illustrated in Figures 3-5, the thread guide support assembly 61 includes two sets of wheels 64,65 and two sets of tracks 66,67, said tracks 66,67 secured to the inside surface 56 of the top portion 3 of housing 2. A thread pointer 68 is secured to the wheels 64, 65 by tube 216 and centered.

The thread pointer 68 is equipped with a revolving bush 69, allowing the writing arm 49 to pull the thread pointer 68 back from the center and creates tension on the thread 62 in all the circumstances.

An adjustment assembly means or thread feeding mechanism is located on the same plane that the wheels 64, 65 are set and are secured to the top portion 3 of housing 2, operable of increasing and decreasing the length of the thread 62 and locking while the writing aπn 49 is revolving. The adjustment assembly means, in the embodiment illustrated includes a bar 202 with one end gear 203 in contact with teeth 80, and a second end gear 204 in contact with gear 205. The gear 205 is attached to a hollow bar 223 which has inner teeth 224. The bar 202 is rotating in a bush 206 supported by a post 207 attached to the skin of shell 56.An extension of the hollow bar 223 is rotating in a bush 208 and is fixed so that it does not move back and forth. Bush 208 is supported by the skin of shell 56. A reciprocating gear 209 is located inside the hollow bar 223 rotating on the same axis and able to move back and forth .The reciprocating gear 209 is a part of rotating bar 210. The rotating bar 210 has a long bush 211 which has a free space for some movement. The bush 211 is supported to the shell 56. A thread container 212 is fixed to the bar 210.One end of guide thread 62 is fixed to this container 212. Along the bar 210 there is a bearing 213. Bearing 213 has two plates, one plate 214 is fixed to the bar 210, the other plate 215 rotates around the axis of the bar 210.The plate 215 is connected to the tube 216. The tube 216 carries the guide thread 62 from container 212 to the thread pointer 68. The tube 216 is fixed on wheels 64 and 65.The tube 216 preferably is U-shaped for ease of thread movement, at the mid point is joined to the thread pointer 68.The guide thread 62 enters the thread pointer 68 and exits from its apex 217. The guide tread 62 continues around the posts 30 and 31 at the tips 218 and 219 and back to the thread pointer 68, and enter from apex 217 and fixed inside the thread pointer 68 at location 220. The thread pointer 68 is in contact with the arm 49 by the bush 69 constantly. Since the thread's length 62 is fixed at all times, there will be tensions between the tips 218 and 219 and the apex 217. These three points 217-218-219 become the three elements for creating the ellipses. The upstanding posts 30, 31 of the first and second arms 6,7 are self- adjustable. As noted above, upstanding posts 30,31 are inserted into a cavity 32,33 in the socket section 20,21 that opens onto the top surface 22,23 of the socket section 20,21 on the hub portion 16,17 connected to the top end 10, 11 of each of the leg portions 8,9 of the first and second arms 6,7. A vertical slot 90,91 in the vertical sides 26,27 and 28,29 of the socket sections 20,21 communicates with the cavity 32,33 in the socket section 20,21. A pin 34,35 is inserted into the slot 32,33 and through the post 30,31. The pin/slot arrangement permits the post 30,31 to move vertically within the cavity 32,33. As best shown if Figure 4 and 9, in the embodiment illustrated there are two panels 70, 71 that adjust the height upstanding posts 30,31 to the plane of the thread feeding guide 63 so all three are located in same plane. For this purpose, panels 70, 71 are provided with arc shaped slots 72, 73. The panels 70,71 are located and secured on the axel 36 together with thrust bearing 48. The thrust bearing's 48 movement is independent from these panels 70, 71. The ends of pins 34, 35 are located within arc shaped slots 72, 73. As the first and second arms 6, 7 are separated by adjusting knob 38 vertical slots 32, 33 and arc shaped slots 72,73 communicate with each other sending the upstanding posts 30,31 to the designated plane. The present invention will work without the height adjusting system, but there will be a slight error in the drawn shapes. In figure 9 the diagram demonstrates the calculation of the radius in which the arc shaped slots 72, 73 on the panels 70, 71 are made. This adjusting system may find a variety of applications in other automated machines.

The revolving writing arm 49 is adjustable in length and is preferably spring loaded so it can adjust itself to the working plane. It is also equipped with a locking system to keep the writing arm 49 in a constant distance from the first and second arms 6, 7 when drawing a circle. The locking system could be as simple as a flexible bar 220 attached to arm 55 having a ball shape 221 at its top end. Arm 54 has a cavity with an indent in the shape of ball 222. For locking, the ball is inserted in to the indent and for release will be pushed in.

The means for the arm to adjust on the working plane are the extensions 223 , 224 of the arm 55, preferably in the shape of two individual cylinders for evenly distributing the forces produced by springs 225,226 and preventing turning and dislocation of the arm. The cylinders 223, 224, are located inside the two cavities that are in the shape of cylinder 227,228 below the spring 225,226 in Figure 6.

In another embodiment (figure 2) a flexible cord 250 at one end is attached to shell 56 and other end is inserted through the slot 251 and attached to the cylinder 224 or 223 keeps the drawing arm's tip 53 in certain plane during the operation.. The location, length, thickness, physical property and angle in which the flexible cord is attached to the shell 56, determines the accuracy of the self adjusting system performance.

A spring 74 connects the revolving writing aim 49 biases the writing arm 49 toward the top portion 3 of housing 2 so the thread 62 will remain in contact with the upstanding posts 30,31 at all times. Two sets of elastic grips 75, 76 cover the upstanding posts 30, 31, so the thread 62 is trapped from dislocation.

As noted above, to draw an ellipse, the total length of the sides of the triangle which forms the ellipses is constant. The thread feeding guide 63 on the revolving writing arm 49, and the upstanding posts 30, 31 on the first and second arms 6,7 form the three points of the triangle. For accuracy purpose, these three points are formed on a horizontal plane and perpendicular with the center of the drawing instrument 1 and parallel to the working plane.

The first and second arms 6, 7 have a partial cone shape cross-section and the revolving writing arm 49 arm has a hollow conical cross-section. By revolving the writing arm 49 arm around the first and second amis 6, 7, the circle or ellipse is formed in a horizontal plane above the working plane while at the same time the marking device 53 at the bottom end 52 of revolving writing arm 49 has marked a circle or an ellipse on the surface of the working plane. With a common compass with one leg touching the working plane, it could incline in infinite directions. When the bottom ends 12, 13 of the first and second arms 6, 7 are placed on the working plane, the drawing instrument it can only incline around the axis of the line between the touching point of the two leg 12 and leg 13 or the focal point. Since the bottom ends 12, 13 of the first and second arms 6,7 remain motionless during the operation, a flat shoe or shoes 77 (see Figure 6) as separate units may be placed on the bottom ends 12, 13 for preventing the first and second arms 6,7 from inclining in those two directions. In addition a level device (not shown) could be provided on the housing 2, while in a leveled working plane to indicate any incline when the shoes are not in place. As noted the location or locations of the bottom ends 12, 13 of the first and second arms 6,7 on the working plane represent the focal point or points of the drawn shape. The size of the drawn shape on the working plane is proportional to the shape that is created above the working plane and depends on the location of the pivot point (axel 36) of the first and second arms 6, 7 above the working plane. The drawing instrument 1 , illustrated in Figures 2-9, has two adjusting knobs, one adjusting knob 38 is located between the first and second arms 6, 7 to determining the distance between the focal points being the bottom ends 12, 13 of the first and second arms 6, 7. A second adjustment knob 78 is provided on the top portion 3 of housing 2 to determine the length of the thread 62. This second adjustment knob 78 is shown as a dial with a groove 79 which is adapted to attach to the housing 2 and rotate in place. Teeth 80 on the outer edge 81 of second adjusting knob 78 engage with the thread feeding mechanism's gear 203, to increase or decrease the length of the thread 62 while turning the knob 78. Means to lock the knob 78 in position can be provided. By adjusting the distance of the bottom ends 12, 13 of the first and second arms 6, 7 and changing the length of the thread 62, any size circle or ellipse is created.

Figure 10 illustrates another embodiment of the present invention being a compass 100, capable of drawing circles of any sizes. Compass 100 comprises of two arms, one stationary 101 and one revolving type 102. A shell 103, and a thrust bearing 104 join these two arms 101,102. A pivot pin 105 acts as an axel, to enable the revolving arm 102 to pivot back and forth toward the central longitudinal axis ot toe compass 100. A threaded bar 106 adjusts the distance of the marking end 107 of the revolving arm 102 from central longitudinal axis of the compass 100, which would be the radius of the circle. The threaded bar 106 has one end 108 pivotally connected to pivot pin 105. Threaded rod 106 is inserted through a threaded hole 109 on shell 103. The end 110 of the threaded bar 106 projecting through hole 109 has a ball 111 for ease of turning threaded rod 106. Turning threaded rod 106 changes the angle of inclination of pivot pin 105 thereby adjusting the position of the revolving arm 102. By revolving the arm 102 around the central longitudinal axis of the compass 100, a circle is drawn on the working plane. A second knob 112 can be provided on the mid-point of the shell 103 and pivot pin 105 maybe attached to the base 113 of knob 112. Holding knob 112 the shell 103 can be rotated on thrust bearing 104.

Figure 11 illustrates another embodiment of the present invention being an apparatus 120 capable of drawing of any size circles and ellipses. The apparatus 120 has a stationary arm 121 and a revolving arm 122. The revolving arm 122 follows the circumference of a circular ring 123. By tilting the ring 123, the marking end 124 of revolving arm 122 will draw ellipses. By moving the ring 123 up and down different sizes are made. The drawn shape on the working plane will be proportional to the shape of the circle ring 123 in orthogonal method. There is a main bar 125 that sets the size and 127 angle of the circle ring 123. As the bar 125 moves up the size of the drawn shape on the working plane will increase. The main bar 125 fits inside a cavity 143 which is centered on arm 121. There are two more bars 126,127 that set the angle of the ring 123, one 126 is fixed in its place, and it is located at the center of the main bar 125 and joined at the top end to a bush 139. The bar 140 is centered and joined inside the ring 123 and fits inside the bush 139 and allows the rotation of the bar 140 around its axel. The bar 140 is the axis in which the ring 123 incline. The other bar 127 is free and sliding inside the main bar 125 in a cavity 142 and is angled slightly toward the central axis of the apparatus 120. These arrangements allow the proper inclination and movements for ring 123. This bar 127 is connected to a U-shaped hook 141 at its top end and holds the ring 123. As bar 127 moves up, it inclines the ring 123 to the required angle.

The revolving arm 122 is connected to the circular ring 123 by a sliding cylinder 129. One end 130 of cylinder 129, remote from the revolving arm 122, has a grip hook 131 in the shape of ring also, positioning the arm 122 in contact with the circumference of the circle ring 123. There is an adjusting knob 132 on the revolving ami that locks the revolving arm 122 in certain height and position and is connected by a flexible cord 134 to sliding cylinder 129. For drawing a circle, the ring 123 is not inclined but is parallel to the working surface and locked in place by minor adjusting knob 135, the main bar 125 which set the height of the ring determining the size and locked, at this arrangement the knob 132 for controlling the flexible cord 134 on revolving arm 122 will remain unlocked, since the plane of the circle ring is already set. To set the apparatus 120 for drawing an ellipse: the minor bar 127 will rise at the right height setting the angle and locked by the adjusting knob 135, the main bar 125 remains unlocked, the knob 138 is the means for locking 125. The flexible cord 134 will be locked by the adjusting knob 132 on the revolving arm 122, by doing this the right plane is set. As the arm 122 revolves, its grip hook 131 or its joint which is a ring, will keep the main ring 123 in the desired plane so in this arrangement the main bar 125 must remain unlocked since it requires a sliding motion up and down. To draw a correct ellipse the apparatus 120 must remain vertical at all the time relative to the working plane. For this purpose a level indicator (not shown) could be in placed on the surface of the shell 145, in addition if extra accuracy is required a flat shoe could be used around the tip of stationary arm 121. Also the arm 121 could be made in two parts. The tip could be separate and the remaining portion form a flat end, this will ensures an accurate drawn shape. Since the stationary arm 121 must remain vertical to the working plane, the revolving arm 122 has two sections, a top section 136 and a bottom section 137 slide-ably attached to the top section 136 to extend the length of the revolving arm 122 as required. The means to hold and rotate the apparatus along its axis is the knob 144 at the mid point of shell 145. Having illustrated and described preferred embodiments of the invention and certain possible modifications thereto, it should be apparent to those of ordinary skill in the art that the invention permits of further modification in arrangement and detail. All such modifications are covered by the scope of the invention.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A drawing instrument capable of drawing circles and ellipses on a working surface, said drawing instrument having a depending stationary arm and a depending revolving arm mounted on a shell, said shell having a mid point that is aligned with a longitudinal vertical axis of the drawing instrument, the revolving arm joined by a pin to the shell from the mid-point of the shell, the shell is rotate-ably secured and centered over a thrust bearing wherein a top end of the stationary arm and a top end of the revolving arm scribe a circle or ellipse in an imaginary plane above and parallel to the working surface and which is transferred by the remote end of the revolving arm to the working plane to draw a circle or ellipse, said circle or ellipse drawn on the working surface are proportional to the circle or ellipse formed by movement of the top end of the stationary arm and top end of the revolving arm

2. A drawing instrument capable of drawing circles and ellipses on a working surface, said drawing instrument having: a housing assembly having a top portion and a bottom portion, wherein the top portion is swivel-ably engaged to the bottom portion; a mid-point of the top portion of the housing assembly aligned with a central longitudinal axis for the drawing instrument; a stationary aπn capable of dividing into first and second arms for the purpose of creating two focal points of an ellipses, said first and second arms having an upper end and a bottom end, the upper end of said first and second arms containing within said housing assembly and the first and second amis extending through the bottom portion of the housing assembly and said first and second arms pivotally connected adjacent their upper ends; Upstanding posts mounted on the upper end of said first and second arms, are self-adjustable in length and foπn the two focal points of the ellipse structure. a writing arm hinged and secured to the mid-point of the top portion of the housing assembly and adapted to move circumferentially around the first and second anus; and a guide thread assembly mounted within the housing assembly, said guide thread assembly including: a guide thread of adjustable length, an adjustment assembly means for adjusting the length of the guide thread and means for holding and retaining any excess guide thread; and a support assembly means for enabling the guide thread assembly to move laterally in relation the longitudinal axis of the drawing instrument.

3. A drawing instrument according to claim 2 wherein said adjustment assembly means includes a rod, wherein a first end of the guide thread is fixed to said rod and the guide thread is spooled around the rod; a least one roller engaged with the rod, wherein rotation of the roller winds or unwinds the guide thread from the rod; a means for rotating the roller to adjust the length of the guide thread; and a locking means for impeding rotation of the roller, such that the length of the guide thread is constant.

4. A drawing instrument according to claim 3 wherein the guide thread assembly has a thread pointer which pivotally coupling the writing arm to the guide thread holder, wherein the thread pointer is secured and supported by a U-shaped tube

5. A drawing instrument according to claim 4 wherein the support assembly means includes a series of wheels and tracks horizontally mounted within the top portion of the housing assembly.

6. A drawing instrument according to claim 5 wherein the guide thread assembly has a hollow tube arranged in circumference at a distance from the longitudinal axis and the upstanding posts, wherein the adjustment assembly means and guide thread holder are mounted and interconnected to the tubing to permit the guide thread to run through the tubing and through the guide thread pointer.

7. A drawing instrument according to claim 6 wherein the partially hollow tube is U-shaped.

8. A drawing instrument according to claim 2 having means for pivoting the first and second arms to adjust the distance between the bottom ends of the first and second arms.

9. A hand held drawing instrument capable of drawing of different sizes circles and ellipses, said drawing instrument having a depending stationary arm and a depending revolving arm mounted on a shell, said shell having a mid point that is aligned with a longitudinal vertical axis of the drawing instrument, the revolving arm joined by a pin to the shell from the mid-point of the shell, the shell is rotate ably secured and centered over a thrust bearing, said revolving arm adapted to follow the circumference of a circular ring, said circular ring tilt ably mounted within the shell, means to adjust the location of the circular ring and means to adjust the angle of the ring.

10. A hand held drawing instrument according to claim 9 wherein the means to adjust the size of the drawn shape includes a slide-able bar located and centered inside the stationary aπn capable of moving the circular ring along the axis of the object, said as the ring moves up, the revolving arm creates greater angle with the axis of the object and consequently result a proportionally greater drawn shapes on the working plane.

11. A hand held drawing instrument according to claim 9 or 10 wherein the means to adjust the angle of the circular ring includes a second bar slide-able and located inside the main bar, a connection hook at the top capable of rising the circular ring up in a proper manner, so the ring could be positioned in the designated angle.

12. A hand held drawing instrument where the arms are conical shape allowing the rotations and capability of drawing any sizes circles and ellipses.

13. A hand held drawing instrument according to claim 1, 2, 3, 9 andl 0 where the revolving arm is self adjusting in length and maintain in working plane by the means of flexible cords or cord attached to a supporting member.

14. A hand held drawing instrument according to claim 1, 2, and 3 where the stationary arms are self adjusting in length from both ends capable of adjusting to the imaginary plane at top and the working plane below, each end posses at least a plate with arc shape slot adjacent to a vertical slot along the socket's wall build in the arm, communicating with the post's pins, positioning the post consequently the tip in the desired plane.