Abstract:
A triangle ruler includes a triangle ruler body defining three corners, three sides, opposing first surface and second surface surrounded by the three sides and three corners and a recessed annular scale located at the center thereof, and a direction indicator including a pendulum and a pointer and pivoting about the center of the recessed annular scale in such a manner that the pivot axis of the direction indicator extends perpendicular to the first and second surfaces of the triangle ruler body, and the effects of the weight of the direction indicator keeps one end of the pointer to constantly indicate a predetermined direction. Thus, the invention combines the functions of a conventional protractor and a conventional triangle ruler to facilitate drawing a variety of different angles of lines.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to rulers, and more particularly to a triangle ruler that can be used to draw a variety of different angles of lines. 
     2. Description of the Related Art 
     People may need to draw a variety of lines by hand to meet different drawing needs. When drawing a variety of different angles of lines, mapping tools such as ruler, triangle ruler and protractor may be used. 
     Linear mapping tools include a ruler marked with a linear scale and a carbon pencil. Subject to the guide of the ruler, the carbon pencil is driven to draw a line segment subject to a predetermined length and then to extend a known line segment. 
     However, the known technique is to draw a line segment of a predetermined length subject to the assistance of one straight edge of the ruler and the linear scale at the ruler. During mapping, one may need to draw vertical lines of predetermined lengths, parallel lines subject to predetermined pitches, and lines that define with the respective vertical lines and respective contained angle. Using one single ruler cannot draw the aforesaid different angles of lines. At this time, a triangle ruler, protractor or other mapping tools shall be needed. However, it is inconvenient to carry a large number of mapping tools and to use different mapping tools during drawing. Therefore, there is room for improvement on conventional mapping tools. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a triangle ruler, which utilizes the effects of gravity to keep a pointer in a constant indication direction so that the triangle ruler combines the functions of a conventional protractor and a conventional triangle ruler for drawing a variety of different angles of lines. 
     To achieve this and other objects of the present invention, a triangle ruler comprises a triangle ruler body and a direction indicator. The triangle ruler body defines three corners, three sides, opposing first surface and second surface surrounded by the three sides and three corners and a recessed annular scale located at the center thereof. The direction indicator comprises a pendulum and a pointer, and is pivotally disposed in the center of the recessed annular scale in such a manner that the pivot axis of the direction indicator extends perpendicular to the first and second surfaces of the triangle ruler body, and the effects of the weight of the direction indicator keeps one end of the pointer to constantly indicate a predetermined direction. 
     Thus, the triangle ruler enables the pointer to constantly indicate a predetermined direction subject to the effects of weight, facilitating measuring angles upon rotation of the triangle ruler body. 
     Further, subject to change of the pivot position between the pendulum and the pointer, the indicating direction of the pointer is relatively changed to fit different users or different application requirements. 
     Further, by means of mounting a see-through protective covers in the two opposite sides of the recessed annular scale, the user can see the triangle ruler from either side during application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a triangle ruler in accordance with the present invention. 
         FIG. 2  is an exploded view of the triangle ruler in accordance with the present invention. 
         FIG. 3  is a schematic sectional view of the triangle ruler in accordance with the present invention. 
         FIG. 4A  is a schematic drawing illustrating an application example of the triangle ruler in accordance with the present invention (I). 
         FIG. 4B  is a schematic drawing illustrating an application example of the triangle ruler in accordance with the present invention (II). 
         FIG. 5  is an exploded view of an alternate form of the triangle ruler in accordance with the present invention. 
         FIG. 6  is an exploded view of another alternate form of the triangle ruler in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Other and further advantages and features of the present invention will be understood by reference to the description of the invention in conjunction with the accompanying drawings where the components are illustrated based on a proportion for explanation but not subject to the actual component proportion. 
     Referring to  FIGS. 1-3 , a perspective view, an exploded view and a schematic sectional view of a triangle ruler in accordance with the present invention is shown. As illustrated, the triangle ruler comprises a triangle ruler body  10 , a direction indicator  20 , two protective covers  30 , and a pivot  40 . 
     The triangle ruler body  10  is a polygon with three corners and three sides, defining opposing first surface and second surface. In this embodiment, the triangle ruler body  10  comprises three linear slots  11  cut through the opposing first surface and second surface and respectively disposed in parallel to the three sides, a flat rail  12  located at and extending along one of the three sides, a variety of linear scales of different systems (such as metric system, English system, etc.) printed on the first surface and/or second surface of the triangle ruler body  10  adjacent to the three sides and the three linear slots  11 , a recessed annular scale  13  located at the center of the triangle ruler body  10 , a circular center opening  14  cut through the opposing first surface and second surface and surrounded by the recessed annular scale  13 , and a plurality of retaining lugs  15  that are stepped lugs respectively extended from the opposing first surface and second surface and equiangularly spaced around the recessed annular scale  13 . Further, the flat rail  12  is disposed in a perpendicular manner relative to the opposing first surface and second surface of the triangle ruler body  10  for supporting the triangle ruler body  10  on a planar surface  50  of an external object in an upright position. 
     The direction indicator  20  comprises a pendulum  21  and a pointer  22 . The direction indicator  20  is pivotally disposed in the center of the recessed annular scale  13  in such a manner that the pivot axis of the direction indicator  20  extends perpendicular to the first surface and the second surface and, the weight of the direction indicator  20  keeps one end of the pointer  22  to constantly indicate a predetermined direction. Further, one end of the pendulum  21  that is connected to the pointer  22  is relatively narrower. The other end of the pendulum  21  is relatively broader. Further, the weight of the pendulum  21  is heavier than the weight of the pointer  22  so that the pendulum  21  can swing freely relative to the triangle ruler body  10 . In this embodiment, the pendulum  21  is shaped like a triangle, having a pivot hole  23 . 
     The two protective covers  30  are transparent circular plate members symmetrically attached to two opposite sides of the the recessed annular scale  13  and kept in flush with the opposing first surface and second surface of the triangle ruler body  10  so that the user can see through the circular opening  14  from each of two opposite sides. Further, each protective cover  30  comprises a center groove  31  at the center of an inner side thereof, and a plurality of engagement members, for example, hooks  32  equiangularly spaced around the periphery corresponding to the retaining lugs  15 . The center grooves  31  of the two protective covers  30  work as axle bearing means. The hooks  32  of the two protective covers  30  are adapted to hook up with the retaining lugs  15  of the triangle ruler body  10 . 
     The pivot  40  is a needle member mounted in the pendulum  21  and supported in the center grooves  31  of the protective covers  30  to suspend the pendulum  21  from the center of the recessed annular scale  13 . In this embodiment, the flat rail  12  works as a reference side for the triangle ruler body  10 . When the reference side, i.e., the flat rail  12  of the triangle ruler body  10  is supported on the planar surface  50 , one end of the pointer  22  indicates the other direction opposite to the reference side. 
     After understanding of the structural features and shapes of the component parts of the triangle ruler, the functioning and effects of the present invention are outlined hereinafter. 
     Referring to  FIGS. 4A and 4B , during application of the triangle ruler, the reference side, i.e., the flat rail  12  of the triangle ruler body  10  is supported on the planar surface  50 . At this time, the pendulum  21  is kept in the resting equilibrium position subject to the effects of gravity, causing the pointer  22  to indicate with its one end in the direction reversed to the reference side, the upward direction relative to the planar surface  50 . At this time, the pointer  22  points out a specific value at the recessed annular scale  13 , and the user can then draw a reference line L 1  along one side of the triangle ruler body  10  opposite to the flat rail  12 , and then bias the triangle ruler body  10  clockwise or counter-clockwise relative to the planar surface  50  to move the recessed annular scale  13  through a predetermined angle subject to the indication of the pointer  22  at the recessed annular scale  13 , and then draw a destination line L 2  that intersects with the reference line L 1  at a predetermined angle. Thus, the user can draw a variety of different angles of lines. In this application example, the angle of the reference line L 1  is 0°; and the angle of the destination line L 2  is 30°; the angle of rotation of the triangle ruler body  10  relative to the planar surface  50  is 30°; the contained angle defined between the reference line L 1  and the destination line L 2  is 30°. Further, the invention has a variety of linear scales of different systems printed on the first surface and/or second surface of the triangle ruler body  10  adjacent to the three sides and the three linear slots  11  for measurement, facilitating drawing a variety of different angles of lines. 
       FIG. 5  illustrates an alternate form of the triangle ruler in accordance with the present invention. According to this alternate form, the pointer  22  has one end thereof pivotally disposed in the center of the recessed annular scale  13  of the triangle ruler body  10 , and the pendulum  21  is disposed between the two opposite ends of the pointer  22 . This design enables the gravity center of the pendulum  21  to be maintained close to the other end of the pointer  22 . Thus, when the reference side, i.e., the flat rail  12  of the triangle ruler body  10  is positioned on a planar surface  50  and then the triangle ruler body  10  is turned relative to the planar surface  50 , the other end of the pointer  22  constantly indicates the reference side, i.e., the bottom side of the planar surface  50 , facilitating angle measurement 
       FIG. 6  illustrates another alternate form of the triangle ruler in accordance with the present invention. According to this alternate form, the pendulum  21  is pivotally disposed in the center of the recessed annular scale  13  of the triangle ruler body  10 , and the pointer  22  extends from one end of the pendulum  21  in reversed directions. Thus, the pendulum  21  and the pointer  22  form a configuration like a balance scale. When the reference side, i.e., the flat rail  12  of the triangle ruler body  10  is positioned on a planar surface  50  and then the triangle ruler body  10  is turned relative to the planar surface  50 , the pointer  22  is kept in parallel to the reference side, working like a level, facilitating angle measurement. 
     In conclusion, the triangle ruler enables the pointer  22  to constantly indicate a predetermined direction subject to the effects of weight, facilitating measuring angles upon rotation of the triangle ruler body  10 . Further, subject to change of the pivot position between the pendulum  21  and the pointer  22 , the indicating direction of the pointer  22  is relatively changed to fit different users or different application requirements. Further, by means of mounting the see-through protective covers  30  in the two opposite sides of the recessed annular scale  13 , the user can see the triangle ruler from either side during application. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.