Endless belt power transmission systems or components – Positive drive pulley or guide roll – With particular belt
Reexamination Certificate
1999-09-01
2001-07-24
Hannon, Thomas R. (Department: 3682)
Endless belt power transmission systems or components
Positive drive pulley or guide roll
With particular belt
C474S205000, C474S207000, C474S252000
Reexamination Certificate
active
06264579
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a toothed belt having functions of aiding in positioning and mounting a desired attachment or part on a predetermined position thereof and identifying that predetermined position, which will hereinafter also be called a “positioning-aiding and position-identifying toothed belt”). More particularly, the present invention relates to a positioning-aiding and position-identifying toothed belt which can be suitably used as a carriage belt for a printer.
2. Description of the Related Art
Toothed belts generally comprise a laminated structure of a tooth rubber member, a backing rubber member and a core wire or tension member embedded between the tooth rubber member and the backing rubber member. To manufacture such toothed belts, an unvulcanized rubber compound sheet, which will be ultimately formed into the above-mentioned tooth rubber and backing rubber members, is wound around a cylindrical tooth-forming die having a tooth cloth sheet and a tension member previously wrapped therearound, so that the rubber compound sheet is formed into a predetermined shape and vulcanized. The resultant vulcanized rubber compound sheet is then cut into rings of predetermined widths to provide a plurality of endless toothed belts.
In recent years, such a toothed belt has been used popularly as a carriage belt of a printer, as schematically illustrated in FIG.
4
. In this illustrated example, the printer carriage belt has a toothed belt portion with a series of driven teeth
10
formed in the inner surface of the belt along part of its length, and a flat belt portion with a non-toothed or flat inner surface. The toothed belt portion with the driven teeth
10
is wound around and engaged with a pulley P
1
with driving teeth (hereinafter “driving toothed pulley”), while the flat belt portion is wound around a non-toothed follower pulley P
2
. Printer carriage C is mounted on a boundary region between the toothed belt portion and the flat belt portion, so that the printer carriage C performs a printing function by being reciprocally moved over a predetermined distance as the toothed carriage belt is driven via the driving toothed pulley P
1
.
In the past, the printer carriage C was mounted on the toothed carriage belt by mounting pieces, projecting from the body of the carriage C, being pressed against the inner and outer surfaces of the carriage belt to thereby tightly grip the belt across the belt's thickness, using a visual carriage-positioning mark put at a predetermined position on the outer surface of the carriage belt.
Although the toothed carriage belt with the visual carriage positioning mark allowed a human operator to attach the printer carriage C accurately to the predetermined position while being guided by the positioning mark, manufacturing such a toothed carriage belt required an additional step of putting the positioning mark on the belt, which considerably increased the costs of the carriage belt. In addition, the printer carriage was apt to be undesirably displaced in position during the mounting operation, which resulted in poor reliability of the mounting operation.
With a view to providing solutions to the above-discussed problems, an improved toothed belt has been proposed, which, as shown in
FIG. 5
, includes a positioning-aiding/position-identifying tooth
12
formed integrally on the tooth rubber member and having a length substantially equal to a sum of the lengths of two driven teeth
10
and one groove between the two driven teeth
10
. With the proposed toothed belt, the human operator can readily ascertain the carriage-mounting position by both the outer appearance and the actual touch of the positioning-aiding/position-identifying tooth
12
which are different from those of the driven teeth
10
, and thereby effectively prevent the positional displacement and deviation of the printer carriage from occurring during the mounting operation.
However, the proposed toothed belt is not satisfactory for the following reasons. Forming the positioning-aiding/position-identifying tooth
12
, having the length substantially equal to two driven teeth
10
and one intervening groove as shown in
FIG. 5
, unavoidably results in a shortage of the tooth rubber material between two driven teeth
10
adjacent to the positioning-aiding/position-identifying tooth
12
. This tooth rubber shortage leads to insufficient projection or height of the positioning-aiding/position-identifying tooth
12
, which would prevent accurate mounting of the printer carriage C on the predetermined position of the belt. If some attempt is made to form the positioning-aiding/position-identifying tooth
12
into a sufficient height or projection, then there would be caused a shortage of the backing rubber material behind the positioning-aiding/position-identifying tooth
12
, which would produce a recess in the outer surface of the tooth belt. In such a case, the tension member
30
, which should have been embedded completely between the tooth rubber member and the backing rubber member, tends to be exposed and the rubber is apt to scale off the belt body, which would reduce the durability of the toothed belt. Consequently, there arises the problem that a desired part, such as a printer carriage, can not be properly mounted on a predetermined position of the proposed toothed belt.
As one approach to eliminate the problems encountered by the proposed toothed belt, an attempt has been made to feed a sufficient amount of the rubber material to the portion of the toothed belt where the positioning-aiding/position-identifying tooth
12
is to be formed. However, this approach is also disadvantageous in that there arises a need not only to change a belt-forming die provided with the cylindrical tooth forming die but also to set special conditions for feeding the unvulcanized rubber compound sheet and special conditions for shaping, vulcanizing, etc. of the unvulcanized rubber compound sheet, so that the belt manufacturing process would become very complex and the manufacturing costs of the toothed belt would increase accordingly.
Similar problems would arise even where the tooth belt is used as a belt for taking out information from a predetermined position of the belt; that is, it is not possible to accurately recognize information, indicative of a printing position or the like, that should be transmitted from the predetermined position.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a positioning-aiding and position-identifying toothed belt which allows a desired part to be reliably mounted on a predetermined position of the belt and permits accurate recognition of information from that predetermined position, and which also achieves superior durability of its positioning-aiding/position-identifying tooth by just requiring a slight modification of a belt-forming die.
To accomplish the above-mentioned object, the present invention provides a toothed belt including at least one positioning-aiding/position-identifying tooth and a large number of driven teeth engageable with a driving toothed pulley. The positioning-aiding/position-identifying tooth is formed in a predetermined positioning area of the toothed belt and has a different shape from that of each of the driven teeth. The toothed belt of the present invention is characterized primarily in that the total amount of rubber used in the positioning-aiding/position-identifying tooth is set to equal an “assumptive” total amount of rubber in one or more imaginary driven teeth that could be formed in the predetermined positioning area if the positioning-aiding/position-identifying tooth was not formed in that area, and the amount of backing rubber used in a portion right behind the positioning-aiding/position-identifying tooth is set to be equal to or greater than an “assumptive amount” of backing rubber in a portion right behind the imaginary driven teeth.
In the present invention, the length, in the longitudinal direction
Arai Tatsuo
Odai Nobuhiro
Charles Marcus
Dann Dorfman Herrell and Skillman
Hannon Thomas R.
Skillman Henry H.
Tsubakimoto Chain Co.
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