BACKGROUND OF THE INVENTION 0001 1. Field of the Invention 0002 The present invention relates to a deceleration device of a tape rule, in particular, a deceleration device equipped in a tape rule capable of retarding the retrieving speed of a tape so as to prevent damaging the tape or scratching the user's finger. 0003 2. Description of the Prior Art 0004 A tape rule plays an important role in many fields of engineering for measuring size of an object. 0005 In an conventional tape rule, when retrieving the tape, the user turns a handle bar or a shank emerging out of the tape rule housing to rotate a reel accommodated therein and the tape is rewound around the reel. However, it is not ideal to rewind the tape manually with such a time consuming and tedious way. For overcoming the above shortcoming. There has appeared an automatic retrieving tape on the market, soon afterwards, it has been discovered that there are some new problems brought up by this new type of tape rule, namely: 0006 1. Retrieving the tape with high speed accompanies the danger of scratching the user's finger due to vibration of the tape. 0007 2. Impingement of the tape tip with high speed onto the housing is prone to damage the tape and shorten its lifetime. 0008 3. Abrasion of high speed moving tape with the edge of housing causes of early wearing of the tape. 0009 In view of the foregoing situation, the inventor of the present invention has conducted intensive research based on many years of experience gained through professional engagement in the manufacturing of related products, with continuous experimentation and improvement culminating in the development of the ingenious deceleration device of a tape rule.

SUMMARY OF THE INVENTION 0010 It is an object of the present invention to provide a deceleration device of a tape rule capable of preventing the danger of scratching the user's finger with the high speed retrieving tape. 0011 It is another object of the present invention to provide a deceleration device of a tape rule capable of preventing the impringement of the high speed retrieving tape onto the tape rule housing causing damage to the tape tip. 0012 It is one more object of the present invention to provide a deceleration device of a tape rule with a simple structure, easy for assembling, and low production cost. 0013 To achieve these and other aforementioned objects, the deceleration device of the present invention comprises a tape rule housing, a reel, and a deceleration unit. Wherein a through hole for an axle is provided at the reel center portion and a transmission gear wheel is coaxially fitted into the reel. The housing is formed of an upper housing and a lower housing, and an axle is passing through the center portion of the upper housing. A speed reduction gear wheel of the deceleration unit is fitted in an aperture provided for the upper housing and in mesh with the transmission gear wheel of the reel such that the reel can rotate 360 about the axle to rewind the tape into the tape rule housing with a reduced speed thereby avoiding possible injury to the user or the tape rule itself.

BRIEF DESCRIPTION OF THE DRAWINGS 0014 For fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which: 0015 FIG. 1 is an exploded view of the deceleration device of a tape rule according to the present invention; 0016 FIG. 2 is a three dimensional view of the deceleration device of a tape rule according to the present invention; 0017 FIGS. 3(A) and 3(B) are illustrative views showing the operation of the deceleration device according to the present invention; 0018 FIG. 4 is an exploded view of the deceleration device of a tape rule in another embodiment of the present invention; 0019 FIG. 5 is a three dimensional view of the deceleration device of a tape rule in another embodiment of the present invention; and 0020 FIGS. 6(A) and 6(B) are illustrative views showing the operation of the deceleration device in another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 0021 Referring to FIGS. 1 and 2, it will be seen that the deceleration device of the present invention comprises a tape rule housing 1; a reel 2; and a deceleration unit 3. The tape rule housing is composed of an upper housing 12 and a lower housing 11. An axle 121 is erected on the center portion of the upper housing 12 through a center hole 22 of the reel 2, and a transmission gear wheel 21 is coaxially fitted to the real 2. By so the reel 2 can rotate about the axle 121 in the housing 1 to extend or retrieve a measuring tape 4. The transmission gear wheel 21 is then covered with the upper housing 12. 0022 The kernel of the deceleration unit 3 is a speed reduction gear wheel 31 which has tapped holes 32,33 provided at two sides thereof. 0023 For assembling, the speed reduction gear wheel 31 is set up in the upper housing 12 via an aperture 122 formed nearby the axle 121, and is in mesh with the transmission gear wheel 21 of the reel 2, the deceleration unit 3 is engaged with the upper housing 12 on its outer surface thereof by screws 5 after aligning the tapped holes 32 and 33 on the deceleration units 3 with the corresponding tapped holes 124 and 123 on the upper housing 12 respectively. 0024 Meanwhile, the deceleration unit 3 may be operated with oil pressure, or pneumatic pressure, or by other mechanical means. 0025 Referring to FIGS. 3(A) and 3(B), in which the operation principle of the deceleration device is illustrated. Since the transmission gear wheel 21 for the reel 2 is in mesh with the speed reduction gear wheel 31 of the deceleration unit 3, the rotational speed of the reel 2 is retarded by the speed reduction gear wheel 31 so that the tape 4 can be retrieved with a rather low speed thereby avoiding the collision of the tape tip 41 with the housing 1 or abrasion of the tape surface 42 and prolonging the lifetime of the tape rule. 0026 For understanding another embodiment of the present invention, reference should be made to FIGS. 4 and 5. The deceleration device in this embodiment comprises a tape rule housing 6; a reel 2; and a deceleration unit 7. The tape rule housing 6 is composed of an upper housing 62 and a lower housing 61. An axle 624 is erected on the center portion of the upper housing 62 through a center hole 22 of the reel 2, and a transmission gear wheel 21 of the deceleration unit 7 is coaxially fitted into the reel 2. By so the real 2 can rotate about the axle 624 in the housing 1 to extend or retrieve a measuring tape 4. The transmission gear wheel 21 is then covered with the upper housing 62. 0027 A flat puser plate 74 with a plurality of slip stop stripes 741 thereon is provided on the outer surface of the deceleration unit 7, and a speed reduction gear wheel 71 is installed beneath its inner surface thereof. One terminal of the deceleration unit 7 has a through hole 72, while the other terminal thereof is formed into a hook 73. 0028 For assembling, the speed reduction gear wheel 71 is set up in the upper housing 62 via an aperture 621 whose size being slightly larger than that of the speed reduction gear wheel 71 and is in mesh with the transmission gear wheel 21 of the reel 2. After aligning the through hole 72 with a circular hole 622 provided on the upper housing 62, and penetrating a hinge pin 8 therethough, the deceleration unit 7 may be hinged to the outer surface of the upper housing 62 and displaceable to and fro thereon by operating the flat pusher plate 74. The hook 73 at one terminal of the deceleration unit 7 is used to hook onto a post 623 provided on the outer surface of the upper housing 62 nearby the aperture 621 for fixing the deceleration unit 7 stably at its position. 0029 Meanwhile, the deceleration unit 7 may be operated with oil pressure, or pneumatic pressure, or by other mechanical means. 0030 Referring to FIGS. 6(A) and 6(B), in which the operation principle of the deceleration device in this embodiment is illustrated. For rapid retrieval of measuring tape 4, reference should be made to FIG. 6(A) in which the flat pusher plate 74 is pushed back a prescribed distance so as to disengage the speed reduction gear wheel 71 from the transmission gear wheel 21 thereby releasing the reel 2 from retaring force of the deceleration unit 7. On the other hand, for Retrieval of measuring tape 4 with a reduced speed, reference should be made to FIG. 6(B) in which the flat pusher plate 74 is pushed forward a prescribed distance so as to engage the hook 73 of the deceleration unit 7 with the post 623 on the outer surface of the upper housing 62 and mesh the speed reduction gear wheel 71 of the deceleration unit 7 with the transmission gear wheel 21 of the reel 2 thereby putting the rotation of reel 2 under control of the retarding force of the deceleration unit 7. 0031 It emerges from the description of the above embodiments that the invention has following noteworthy advantages, namely: 0032 (1) The deceleration device of the present invention is able to prevent the danger of scratching the user's finger by the tape retrieving in high speed. 0033 (2) The deceleration device of the present invention is able to prevent damage to the tape tip caused by impringement of the high speed retrieving tape into the housing or abrasion of the tape itself and prolong the lifetime of the tape rule. 0034 Although the invention has been described in terms of preferred embodiments, it is apparent the numerous variations ant modifications may be made without departing from the true spirit and scope thereof, as set forth in the following claims.