Tape rule with automatic blade extension mechanism

• US 6,550,155 B1
• Filed: 02/05/2002
• Issued: 04/22/2003
• Est. Priority Date: 02/05/2002
• Status: Expired due to Fees

• Current Assignee: Cheng-Hui Hsu
• Original Assignee: Cheng-Hui Hsu
• Inventors: Hsu, Cheng-Hui
• Primary Examiner(s): Bennett, G. Bradley
• Application Number:
  US10/062,767
• Time in Patent Office: 441 Days
• Field of Search: 337/55, 337/56, 337/60, 337/61, 334/13, 334/14, 242/389, 242/394, 242/395, 242/395.1
• US Class Current: 33/755
• CPC Class Codes: G01B 2003/1015 engaging the tape in a direction transversal to the tape itself
• CPC Class Codes: G01B 2003/1025 operated manually, e.g. crank-handles
• CPC Class Codes: G01B 2003/1038 by translatory motion operation
• CPC Class Codes: G01B 3/1005 Means for controlling winding or unwinding of tapes
• CPC Class Codes: G01B 3/1056 Tape end arrangements, e.g. end-hooks

Abstract

A tape rule with an automatic blade extension mechanism in which the internal ruler blade reel is not equipped with a center-wound, spiral retraction spring. The torsion developed by winding the steel ruler blade around the reel is of sufficient magnitude such that when the ruler blade is released, it automatically extends to facilitate taking measurements. As such, the present invention is of higher industrial and practical value.

Claims

1. A tape rule with an automatic blade extension mechanism comprised of a front case half, a rear case half, a reel, a rewind hub, a rewind gear, a locking component, and a gear cover, of which:

The said front case half is of one-piece plastic construction;

the said front case half has a round opening formed in its posterior section and, furthermore, with a bearing rim disposed towards the interior, a plurality of raised, inward facing threaded holes along the circumference of the said bearing rim, and a groove situated along the lateral inner side of the said bearing rim;

a plurality of elevated threaded holes are distributed along the interior sides of the said front case half and, furthermore, a prop rest of a tubular shape extends inward near the forward edge of the said front case half;

The said rear case half is of one-piece plastic construction;

the said rear case half has a locating ring at the center of its interior side and a bearing surface within the said locating ring;

a plurality of elevated fastening holes are formed along the interior sides of the said rear case half, a curved locating element extends along the interior portion at the back of the said rear case half and, furthermore, an arrestor button is inserted into the forward edge of the said rear case half;

The said reel consists of a left flange, a right flange, and a ruler blade;

the said left flange is disc-shaped and has a gear projecting from the center of its outer side;

the said left flange has tubular spool extending from its inner side and, furthermore, a locating notch is formed in the extremity of the said tubular spool;

the said tubular spool has a T-shaped clip slot in its body and, furthermore, a threaded post extends through the center of the said tubular spool;

the said right flange is disc-shaped and has a circular raised fitting at its center and a locating block extends from the said raised fitting;

the said right flange has a square member projecting from the center of its inner side and, furthermore, a hole is disposed through the center of the said square member;

additionally, the said right flange has a locating edge on its outer side, with the said right flange also consisting of a screw that is inserted into the hole and then fastened to the threaded post at the center of the said left flange and, furthermore, the said locating block is fitted into the said locating notch in the extremity of the said tubular spool at the inner side of the said left flange, following which the T-shaped catch end of the said ruler blade is inserted and fixed into the said T-shaped clip slot in the body of the said tubular spool on the said left flange, and the entire said ruler blade is wound around the said reel;

The said rewind hub has a convex block contoured as a split pair along its outer side and a linkage hole is formed through the posterior side of the said convex block;

the said rewind hub has a square collar projecting from its center;

the said rewind hub has a drive hole through its center, with the said drive hole being square at the outer lateral extremity of the said rewind hub and round at the inner lateral extremity of the said rewind hub; and

the said rewind hub has a bearing rim formed into the surface of its inner side;

the said rewind hub also consists of a crank having a linkage hole through one end and the said crank has a grip rod projecting from its other end;

the arrangement of the said crank is such that a hinge pin is inserted into the linkage hole in the two said convex blocks and into the said linkage hole of the said crank, enabling the said crank to pivot 180 degrees around the axis of the said hinge pin;

The said rewind gear has a star-shaped serrated hole formed in its center, with ring gear teeth disposed along the interior sides of the said rewind gear;

The said locking component is cylindrical along its center portion and has a square push button at one extremity and a star-shaped serrated tip flanging outward from its other extremity, with the said locking component having a hole disposed in the center of the said star-shaped serrated tip for the entry of a spring;

The said gear cover is disc-shaped and has a locating ring projecting from the center of one side and, furthermore, a hole disposed laterally to the said locating ring; and

the said gear cover has a plurality of fastening holes along its outer circumference;

The said rewind hub is placed into the said bearing rim and the said groove of the said front case half, the said rewind gear is then fitted onto the said bearing rim at the inner side of the said rewind hub;

the said locking component is inserted through the said rewind gear and into the said drive hole of the said rewind hub such that the said square push button at one extremity of the said locking component extends through the said rewind hub drive hole;

the said star-shaped serrated tip at the other end of the said locking component is inserted into the said star-shaped serrated hole in the said rewind gear;

a respective plurality of screws are inserted through the plurality of said fastening holes of the said gear cover and then secured into the said threaded holes of the said front case half;

the said reel is inserted into the said gear cover hole by means of the said gear at the center of its said left flange, which is then enmeshed with the said ring gear teeth along the along the interior sides of the said rewind gear;

the said front case half and the said rear case half are placed together with the said reel cradled between the said curved locating element and the said locating ring of the said rear case half, a plurality of screws are inserted through the said rear case half fastening holes and secured into the said front case half threaded holes to thereby assemble the present invention into a single structural entity.