Patent Publication Number: US-6983545-B2

Title: Compass and compass-cutter with ratchet mechanism

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a division of patent application Ser. No. 10/247,710, filed Sep. 20, 2002 now U.S. Pat. No. 6,889,440, now allowed, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Japan Patent Application No. 2001-291444, filed Sep. 25, 2001. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a compass provided with a ratchet mechanism. In particular, the present invention also relates to, not only a compass for drawing a circle, but also a compass-cutter for cutting a cloth in circular configuration, the compass-cutter being provided with a ratchet mechanism. 
   2. Description of the Related Art 
     FIG. 1  shows an ordinary compass  10 , which is used for drawing a circle on, for example, a drawing paper. The compass  10  comprises a pair of legs  11 ,  15  the open angle therebetween can be adjusted, and a manipulate portion  19  which is provided on a location where the legs  11  and  15  are interconnected. The leg  11  is provided with a needle  12  on its distal end, and the other leg  15  carries a pencil  16  on its distal end. 
   When a user draws a circle, the user pinches the manipulate portion  19  with fingers, and moves the pencil  16  along a circular path, with the needle  12  stuck on a drawing paper being the center of the circular path. During this operation, it may be difficult to draw up a complete circle with 360 degrees in single action without re-pinching the manipulate portion with fingers. Therefore, the user often re-pinches the manipulate portion on the midway before a complete circle, and thereafter finishes the circle. This action of re-pinch is cumbersome, and if this re-pinch action is poor, the user can not draw a precise circle, because of unintentional shift of the needle  12 , for example. 
   On the other hand, if the user forcibly tries to draw up a complete circle with 360 degrees in single action, an excessive force would shift the needle  12  stuck on a drawing paper, and as a result, a precise circle could not be drawn. 
   The above disadvantage may be true, not only in a compass for drawing a circle, but also in a compass-cutter for cutting an object in circular configuration. 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a compass and a compass-cutter, which can be smoothly manipulated with simple manipulating actions. 
   The present invention was completed in order to effectively solve the problems, and provide a compass and a compass-cutter as described below. 
   The feature of the present invention lies in that a manipulate portion of a compass comprises a ratchet mechanism. This feature can be applied not only to a compass for drawing a circle, but also to a compass-cutter for cutting an object in circular configuration. Note that an expression “drawing a circle” covers not only the fact to draw a circle with a pencil carried on one leg of a compass, but also the fact to draw a circle with a needle on metal surface. 
   Generally, the manipulate portion is intended for manipulated with fingers. But, when the compass is large sized, or when the object to be cut is hard, it may be preferable to manipulate the compass with a tool. In such the case, it is preferable that at least a part of the manipulate portion has a configuration adopted to be engaged with a tool. 
   Further, the manipulate portion comprising the ratchet mechanism can be constituted as a separated component from a body of the compass. In such the case, a commercially available tool (for example, a ratchet handle for socket wrench, and so on) can be used as the manipulate portion comprising the ratchet mechanism. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings. 
       FIG. 1  shows an elevation of a conventional compass for drawing a circle. 
       FIG. 2  shows a perspective view of a compass-cutter according to an embodiment of the present invention. 
       FIG. 3  shows a exploded perspective view of the compass-cutter in  FIG. 2 . 
       FIG. 4  shows a partially ruptured perspective view of the compass-cutter in  FIG. 2 . 
       FIG. 5  shows a modification wherein the manipulate portion has a hexagonal head adopted to be engaged with a spanner. 
       FIG. 6  shows a perspective view of another embodiment wherein the compass body and the ratchet mechanism are separated. 
       FIG. 7  shows a perspective view of another embodiment wherein a rotary blade is employed. 
       FIG. 8  shows a perspective view of another embodiment wherein the present invention is applied to a compass for drawing a circle. 
       FIG. 9  is a diagrammatic view explaining the principle of another ratchet mechanism which can be employed in the present invention. 
       FIG. 10  is a perspective view showing another embodiment of the present invention, wherein the manipulate portion of the compass-cutter can be always located at the intermediate position between the rotation center and the blade. 
       FIG. 11  is an explanatory view showing a modification to the compass-cutter to that shown in  FIG. 10 . 
       FIG. 12  is an explanatory view showing another modification to the compass-cutter to that shown in  FIG. 10 . 
       FIG. 13  is a perspective view showing another example of the manipulate portion of the compass-cutter. 
       FIG. 14  is a perspective view showing still another example of the manipulate portion of the compass-cutter. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The embodiments of the present invention will be described in detail below, with reference to the accompanying drawings.  FIGS. 2 to 4  show a compass-cutter  20  according to an embodiment of the present invention.  FIG. 2  shows a whole perspective view,  FIG. 3  shows an exploded perspective view, and  FIG. 4  shows a partially ruptured perspective view. 
   The compass-cutter  20  is used for cutting a paper or a cloth in circular configuration. In use, a user sticks the needle  61  at the center of a circle, and pinches a manipulate portion  30  with fingers so as to move a blade  81  along a circular path. The manipulate portion  30  is provided with a ratchet mechanism (one-way clutch) therein. 
   The ratchet mechanism means what transmits a rotational driving force only in one direction, and the ratchet mechanism itself is known. As specific constructions of the ratchet mechanism, a variety ones are known, and therefore, in the present invention, the specific construction of the ratchet mechanism is not limited to particular one.  FIGS. 3 and 4  are intended to show an example of the ratchet mechanism. 
   (Construction of a Ratchet Mechanism) 
   At the upper side of a compass body  50 , the first cylindrical member  34  is fixed, so that the compass body  50  and the first cylindrical member  34  can not be relatively rotated. The first cylindrical member  34  is provided with teeth at its upper end. 
   In  FIG. 3 , a member  33  located at upper side of the first cylindrical member  34  comprises an upper square column  33   a  and a lower second cylindrical member  33   b,  the column  33   a  and the member  33   b  being integrally formed. The member  33  is inserted in the body  31  of the manipulate portion with a spring  32  located therebetween. In  FIG. 4 , showing an assembled condition, the member  33  is forced downwardly toward the first cylindrical member  34 . In this condition, teeth formed at lower end of the second cylindrical member  33   b  are just fitted with the teeth formed at upper end of the first cylindrical member  34  (refer to  FIG. 4 ). 
   The member  33  is connected to the body  31  of the manipulate portion, at its square column  33   a,  and therefore, the member  33  can not be rotated relatively to the body  31  of the manipulate portion. But, in axial direction, the member  33  can slide relatively to the body  31  of the manipulate portion. 
   Note that, if a relatively heavy member is employed as the member  33 , the spring  32  can be omitted. In  FIG. 3 , force of the spring  32  pushes the member  33  downwardly toward the first cylindrical member  34 . But, if the member  33  itself is relatively heavy, the member  33  would be pressed against the first cylindrical member  34  with self-respect. 
   (Function Ratchet Mechanism) 
   The ratchet mechanism is constituted as above. Thus, when the manipulate portion  30  is rotated in the direction of “A” in  FIG. 4 , both of the teeth formed on the first cylindrical member  34  and on the second cylindrical member  33   b  are engaged, so that the blade also rotates in the same direction. On the other hand, when the manipulate portion  30  is rotated in the direction of “B” in  FIG. 4 , the teeth are not engaged and the members  34  and  33   b  are skidding to each other. Thus, the blade  81  keeps a constant location. 
   Therefore, firstly, pinching the manipulate portion  30  with fingers to rotate the manipulate portion  30  in the direction of “A”, so as to cut a paper (or cloth) with the blade  81 ; when the cutting operation proceeds to some extent, then returning back the manipulate portion  30  with skidding in the direction of “B” (at this time, the blade  81  keeps a constant location); again, pinching the manipulate portion  30  with fingers to rotate the manipulate portion  30  in the direction of “A” , to proceed the cutting. Repeating the above procedures, the user can smoothly rotate the blade at 360 degree with simple hand actions and without immoderate hand action. Moreover, there is no need for re-pinching the manipulate portion  30  during the cutting operation. 
   (Other Mechanism of the Compass-cutter  20 ) 
   The remarkable construction and function of the compass-cutter  20  according to the present invention are described as above, and the other matters are generally well known. Thus, the summarized explanations are made below. 
   The blade  81  is mounted at one end of a horizontal bar  70  via a mount plate  80 . A screw member  82  is intended for exchanging the blade  81  with another blade. The horizontal bar  70  is carried on the compass body  50  so as to slide in horizontal direction. The interval between the needle  61  and the blade  81  (namely, the radius of circle) can be adjusted with a bolt  52  and screw member  51 . The horizontal bar  70  bears a scale  71  for indicating the interval. 
   The needle  61  is located co-axially with the manipulate portion  30 , and is fix to lower side of the compass body  50  via a shaft member  60 . 
   (A Modification of the Manipulate Portion) 
   In  FIG. 5 , there is shown a modification of the compass-cutter  20  described before. In this modification, the head  31   a  of the body  31  of the manipulate portion is formed in hexagonal configuration. As to the other constructions, the modification has the same ones as those of the compass-cutter  20 , and a ratchet mechanism is enclosed in the manipulate portion  30 . 
   The hexagonal head  31   a  of the body  31  is to be engaged with a spanner  100 . That is, the compass-cutter in  FIG. 5  is not intended for using with directly pinching the manipulate portion with fingers, but is intended for using with the spanner  100 . Such the modification is effective, when the object to be cut is hard, or the radius of circle is large. 
   In the shown modification, the head  31   a  is made hexagonal so as to be engaged with the spanner  100 . But, the configuration of the head does not need to be hexagonal, and any suitable configurations (for example, rectangular) can be employed as long as the configurations match with a tool to be used (spanner, monkey wrench, wrench, and so on). Further, the configuration can be provided at other location than the head of the body  31 . For example, the circumferential wall of the body  31  can be partially cut out, so as to be engaged with a tool. 
   (An Embodiment Wherein the Compass Body and the Ratchet Mechanism are Separated) 
   In  FIG. 6 , there is shown an embodiment wherein the compass body and the ratchet mechanism are separated. This compass-cutter  120  comprises a compass body  150  carrying a blade, and a manipulate portion  130  provided with a ratchet mechanism. The manipulate portion  130  is detachably connected to the compass body  150 . 
   In the compass-cutter  120 , the cylindrical member  151  fixed at upper side of the compass body  150  is not provided with a ratchet mechanism, and alternatively, a square recess  152  is formed at the center of the cylindrical member  151 . A ratchet mechanism is enclosed in the end portion  131  of the manipulate portion  130 . From the end portion  131 , a square protrusion extends downwardly to be engaged in the square recess  152 , though the protrusion does not appear in  FIG. 6 . With the protrusion (not shown) being engaged in the square recess  152 , a user manipulates the handle  132  to cut an object in circular configuration. 
   In the compass-cutter  120  shown in  FIG. 6 , a commercially available tool, such as a ratchet handle for socket wrench, can be employed as the manipulate portion  130 , and can advantageously lower the manufacturing cost. 
   (Other Embodiments) 
     FIGS. 7 and 8  show other embodiments of the present invention. In the embodiment in  FIG. 7 , the blade  81  of the compass-cutter  20  in  FIG. 2  is substituted with a rotary blade  85 . The rotary blade  85  is suitable for thin objects to be cut, such as a cloth. In the embodiment in  FIG. 8 , a ratchet mechanism is provided to a compass for drawing a circle, and therefore, the blade  81  of the compass-cutter  20  in  FIG. 2  is substituted with a pencil  88 , which is carried on a horizontal bar. Alternatively, substituting for the blade  81 , a needle (not shown) can be carried on the horizontal bar, and then a circle can be drawn on a metal surface. 
   Both of the compass-cutter  220  in  FIG. 7  and the compass  320  in  FIG. 8  are provided with a ratchet mechanism like that employed in the compass-cutter  20  in  FIG. 2 . Therefore, as a modification of the compass-cutter  220  or the compass  320 , the configuration of the manipulate portion thereof can be one adopted to be engaged with a tool. Further, the compass body and the manipulate portion provided with the ratchet mechanism can be separated, like in the above-mentioned. 
   (Another Ratchet Mechanism) 
   Next, with reference to  FIG. 9 , another example of a ratchet mechanism is explained. As described before, the word “ratchet mechanism” in the present invention means what transmits a rotational driving force only in one direction, and the specific construction of the ratchet mechanism is not limited to particular one. The mechanism shown in  FIG. 9  is so-called a one-way clutch, and this also belongs to the “ratchet mechanism” in the present invention, because the one-way clutch transmits a rotational driving force only in one direction. Note that, the construction of this one-way clutch itself is also known. 
     FIG. 9  is a cross sectional view explaining the mechanism of the one-way clutch diagrammatically. A center shaft  500  and an outer sheath  600  are arranged co-axially. The outer sheath  600  corresponds to the body  31  of the manipulate portion in  FIG. 3 , and the center shaft  500  is fixed to the compass body  50  (refer to  FIG. 3 ). When the outer sheath  600  (body of manipulate portion) is rotated in the direction of “B” in  FIG. 9 , the rotating driving force is transmitted to the center shaft  500  so as to rotate the compass. On the other hand, when the outer sheath  600  (body of manipulate portion) is rotated in the direction of “A” in  FIG. 9 , the rotating driving force is not transmitted to the center shaft  500 , and thus the outer sheath  600  rotates with skidding. That is, the compass does not rotate and keeps a constant location. The principle thereof is as follows. 
   The outer sheath  600  carries a plurality of circular columns on its inner surface by means of a holding mechanism (not shown). Although three columns  501 ,  502 , and  503  of them are only shown in  FIG. 9 , actually a lot of circular columns are arranged along the whole inner surface of the outer sheath  600 . Each of the circular columns is held in the gap between the center shaft  500  and the outer sheath  600 , with its longitudinal axis being parallel to the axes of the center shaft  500  and the outer sheath  600 . 
   As partially enlarged in  FIG. 9 , on the inner surface of the outer sheath  600 , there is formed many recesses, each of which receives the individual circular column. Each of the recesses comprises a gentle first slope  601   a,    602   a,    603   a  and a steep second slope  601   b,    602   b,    603   b.  Each of the circular columns  501 ,  502 ,  503  is forced in the direction “A” by a spring (not shown and held at the outer sheath  600 ). 
   When the outer sheath  600  is rotated in the same direction (the arrow “A”) as the direction to which the urging force of the spring is applied, the rotational torque applied to the outer sheath  600  is not transmitted to the center shaft  500 , and therefore, the outer sheath  600  rotates with skidding. Each of the circular columns  501 ,  502 ,  503  follows the gentle first slope  601   a,    602   a,    603   a  under the urging force of the spring. 
   Contrary, when the outer sheath  600  is rotated in the counter direction (the arrow “B”) to the direction to which the urging force of the spring is applied, each of the circular columns  501 ,  502 ,  503  is pressed against the gentle first slope  601   a,    602   a,    603   a  under the urging force of the spring. As a result, since the diameter of individual circular column is set larger than the gap between the center shaft  500  and the outer sheath  600 , each of the circular columns  501 ,  502 ,  503  bites into the wedged-space between the gentle first slope and the outer surface of the center shaft  500 , so that the rotational torque applied to the outer sheath  600  is transmitted, via the circular columns, to the center shaft  500 , and therefore, the compass rotates. 
   (A Compass-cutter Wherein the Manipulate Portion can be Always Located at Intermediate Position Between the Rotation Center and the Blade) 
     FIG. 10  shows a compass-cutter according to another embodiment of the present invention. The manipulate portion  960  of this compass-cutter is provided with the same ratchet mechanism as that employed in the compass shown in  FIGS. 2 to 4 , and is fixed to a compass body  950 . 
   However, in the embodiment in  FIG. 10 , a needle  701  defining the rotation center of the compass is not fixed to the compass body  950 , but is fixed to an distal end of a shaft member (first leg)  700 . The shaft member extends downwardly from a slide member  750  which is separated from the compass body  950 . With adjusting the screw members  951  and  751 , both of the compass body  950  and the slide member  750  can slide along a horizontal bar (lateral bar)  900 , and fixed at any position as desired. The mechanism therefor is the same as that employed in the embodiment in  FIG. 3 . 
   In the compass-cutter in  FIG. 10 , adjusting the locations of the compass body  950  and the slide member  750 , the manipulate portion  960  can be always located at intermediate position between the rotation center (the position of the needle  701 ) and the blade  801 , regardless of the interval length between the rotation center (the position of the needle  701 ) and the blade  801 . Further, sliding in parallel the slide member  750  along the horizontal bar  900 , the rotation radius of the blade  801  fixed to the mount plate (second leg)  800  can be adjusted, and the rotating plane of the blade  801  is always kept in parallel to the center axis of the needle  701 . 
   Such the construction is particularly advantageous in a compass-cutter wherein a blade is utilized for cutting an object in circular configuration. This is explained below. 
   Suppose that a blade is set to one leg of a compass as shown in  FIG. 1 , in which the rotation radius is adjusted with an open angle between two legs  11  and  15 . In that case, as the rotation radius changes, the angle between the rotating plane of the blade and the axis of the needle  12  also changes. This means that the relative angle of the rotating plane of the blade to the surface of the object to be cut (for example, a cloth) changes, and means that depending on the relative angle value (in other words, depending on the rotation radius), smooth cutting operation just along a desired cutting line may be prevented. 
   To the contrary, in the construction in  FIG. 10  (also in  FIGS. 3 and 7 ), the rotating plane of the blade  801  can be always kept in parallel to the axis of the needle  701 , regardless of the interval length between the rotation center (the position of the needle  701 ) and the blade  801 . As a result, the rotating plane of the blade  801  can be always kept in a nearly right angle to the object to be cut, regardless of the rotation radius. Moreover, since the manipulate portion  960  can be always located at intermediate position between the rotation center (the position of the needle  701 ) and the blade  801 , it is possible to deliver the pushing force transmitted from user&#39;s hand almost equally to the needle  701  and to the blade  801 . This is true when the rotary blade  801  in  FIG. 10  is substituted with the stationary blade  81  in  FIG. 2 . 
   As explained above, also with the compass-cutter constructed as shown in  FIG. 10 , cutting operation can be done smoothly with simple manipulating actions. It is to be noted that even in a compass-cutter without ratchet mechanism at its manipulate portion, the same advantage as that explained with reference to  FIG. 10  can be achieved. For example, other than the ratchet mechanism, manipulate portions as shown in  FIGS. 13 and 14  can be employed. 
   (Manipulate Portion in  FIG. 13 ) 
   A rod  981  is stationary fixed to the compass-body  950 . A treaded end portion  982  of the rod  981  passes through an opening  991  formed on an upper wall of a sheath  990 , and a nut  983  is engaged with the treaded end portion  982 . As a result, the sheath  990  is attached to the rod  981  so as to freely rotate in both directions. 
   When such the manipulate portion is employed, the cutting operation with the rotary blade  801  is to be conducted by revolving use&#39;s hand holding the sheath  990  around the needle  701 . In this construction, there are brought some merits, that is, the cutting operation can be conducted in both of left and right directions; the cutting operation can be easily conducted regardless of a left-handed user or a right-handed user; and the manipulate portion can be simplified compared as the embodiment employing the ratchet mechanism. 
   Note that in the case of the manipulate portion in  FIG. 13 , when the compass body  950  is fixed at the location near the blade  801 , the cutting operation can be more easy. 
   (Manipulate Portion in  FIG. 14 ) 
   The manipulate portion comprises one rod  955 , which is stationary fixed to the compass body  950 . This construction is inferior to the construction in  FIG. 13  in view of the easy operation, but brings a merit that the construction is further simplified. 
   In the compass-cutters in  FIGS. 13 and 14 , of course, the rotary blade  801  can be substituted with the blade  81  such as shown in  FIG. 2 , or with the pencil  88  such as shown in  FIG. 8 . 
   (Mechanism for Positioning the Manipulate Portion at Intermediate Position Between the Rotation Center and the Blade) 
   In  FIGS. 10 and 11 , modifications to the compass-cutter in  FIG. 10  are shown. Both of the modifications are provided with a mechanism, with which a user can easily locate the manipulate portion at intermediate position between the rotation center and the blade (center-positioning). 
   In the compass-cutter in  FIG. 11 , the center-positioning of the manipulate portion  960  can be done with utilizing springs  965  and  966 . The springs  965  and  966  are accommodated in an elongated opening  901  which is formed along the longitudinal direction of a horizontal bar  900 . One end  965   a  of the spring  965  (second spring) is fixed to the left end  901   a  (in  FIG. 11 ) of the elongated opening, and the other end  965   b  is fixed to a fix pin  955  arranged on the compass body  950 . On the other hand, one end  966   a  of the spring  966  (first spring) is fixed to the fix pin  955 , and the other end  966   b  is fixed to a fix pin  755  arranged on the slide member  750 . 
   Two springs  965  and  966  have the equal spring-rate. Thus, tightening the screw member  751  to fix the position of the slide member  750 , while loosening the screw member  951  to allow the compass body  950  to slide freely, the manipulate portion  960  is automatically located at the intermediate position between the rotation center (the position of the needle  701 ) and the blade  801 , under the urging force of the spring  965 ,  966 . Finally, tightening the screw member  951  to fix the position of the compass body  950 . 
   In the embodiment in  FIG. 11 , the mount plate (first leg)  800  is directly attached to the horizontal bar  900 , and one end  965   a  of the spring  965  is connected directly to the horizontal bar itself. Thus, equivalently, the manipulate portion  960  and the mount plate  800  are connected via the spring  965 . Note that the mount plate  800  may be made to be able to freely slide relative to the horizontal bar  900 , and one end  965   a  of the spring  965  may be attached to such the mount plate  800 , like in the embodiment in  FIG. 12 . 
   In the compass-cutter in  FIG. 12 , a screw member  970  is utilized to conduct the center-positioning of the manipulate portion  960 . The screw member  970  comprises a center-located dial portion  971 , a left screw  972  and a right screw  973 , the screws  972  and  973  projecting opposite from the dial portion  971  co-axially. The screw member  970  is located in an elongated opening  902  formed along the longitudinal direction of the horizontal bar  900 , and the dial portion  971  is exposed to outward through a slit formed on the compass body  950   a.    
   The mount plate  800  carrying the blade  801  is fixed to a slide member  800   a,  and engaged with the left screw  972  via the slide member  800   a.  That is, the slide member  800   a  is provided with a threaded portion (not shown) therein, and this threaded portion is engaged with the left screw  972 . On the other hand, the slide member  750   a  carrying the needle  701  is provided with a threaded portion (not shown) therein, and this threaded portion is engaged with the right screw  973 . 
   Since the left screw  972  and the right screw  973  are equally leaded in counter direction, rotating the dial portion  971 , exposed on the side wall of the compass body  950   a,  with finger make the blade  801  and the needle  701  separate away or approach to with each other, so as to always locate the manipulate portion  950  at the intermediate position therebetween. 
   Explained as above, in the compass-cutters in  FIGS. 11 and 12 , the manipulate portion  960  can be positioned at the intermediate position between the rotation center and the blade can be secured, easily and securely. 
   Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.