Advancing material of indeterminate length – By orbitally traveling material-engaging surface – Including details of roll or mount
Reexamination Certificate
2000-08-04
2002-10-22
Mansen, Michael R. (Department: 3654)
Advancing material of indeterminate length
By orbitally traveling material-engaging surface
Including details of roll or mount
C226S180000, C384S192000, C384S297000, C384S909000
Reexamination Certificate
active
06467669
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pinch roller apparatus used for a tape driving apparatus in a video tape recorder, an audio tape recorder and the like.
2. Description of the Prior Art
The pinch roller apparatus used for the tape driving apparatus is structured such as to grip a tape between a pinch roller main body and a capstan and feed the tape in accordance with a driving operation of the capstan. In order to securely feed the tape moving between the pinch roller apparatus and the capstan in a stable state, the pinch roller apparatus is required a self-aligning function for following an incline of the capstan. Accordingly, a bearing having a self-aligning function is employed for the pinch roller apparatus.
In recent years, in place of an expensive ball bearing, for example, a resin plain bearing described in Japanese Patent Unexamined Publication No. 10-49935 and 10-228692 or an oilless plain bearing described in Japanese Utility Model Publication No. 8-9447 are used for the bearing of the pinch roller apparatus having the self-aligning function.
The pinch roller apparatus mentioned above is generally structured in the following manner. That is, the pinch roller apparatus is formed by providing a rubber-like elastic body on an outer periphery of a sleeve made of a metal such as an aluminum, a brass and the like or a resin so as to form a pinch roller main body and pressure fitting the plain bearing into the sleeve. Then, it is mounted by inserting a pinch roller shaft having one end mounted to an arm into the plain bearing. The pinch roller apparatus is structured such as to press the pinch roller main body to the capstan by moving the arm so as to grip the tape. The self-aligning function of the pinch roller corresponds to an operation of making a rotary shaft of the pinch roller main body in parallel to the capstan due to a clearance between the pinch roller shaft and the plain bearing.
As mentioned above, the self-aligning function in the conventional pinch roller apparatus is performed by the pinch roller main body being inclined in a direction of the capstan due to the clearance between the pinch roller shaft and the plain bearing. However, the pinch roller main body is also inclined in a direction perpendicular to the direction of the capstan in addition to the direction of the capstan, that is, a moving direction of the tape. Accordingly, in view of a moving stability of the tape, it is preferable that the clearance of the plain bearing corresponding to the incline of the pinch roller main body is set as small as possible.
Further, in the case that the plain bearing is a resin plain bearing, it has been hard to secure an accuracy of a size since a shrinkage is generated after being formed by a metal mold. Further, the plain bearing is, as mentioned above, assembled by being pressure fitted into the sleeve forming the pinch roller main body. However, an inner diameter of the sleeve itself is not always fixed and the plain bearing is shrunk in a radial direction at a time of being pressure fitted into the sleeve. Accordingly, it has been significantly hard to accurately form the inner diameter of the plain bearing at a time of assembling as the pinch roller due to an error of the inner diameter of the sleeve as well as an error in a size of the plain bearing itself.
Further, when the clearance between the pinch roller shaft and the plain bearing is too small, a smooth rotation of the pinch roller main body is restricted, and it is impossible to obtain a sufficient self-aligning function. On the contrary, when the clearance between the pinch roller shaft and the plain bearing is too large, as well as a durability of the plain bearing is deteriorated, there is a problem that it is impossible to stably move the tape due to a point contact between the capstan and the roller main body.
On the contrary, the pinch roller apparatus described in Japanese Patent Unexamined Publication No. 10-228692 is structured such as not to self-align in accordance with the clearance but to self-align in accordance with an elasticity of the plain bearing, in order to solve the problem generated in the case that the clearance between the pinch roller shaft and the plain bearing is large. Accordingly, as well as the plain bearing is made of a resin, Young's modulus of the resin is set to 10 kgf/mm
2
or more and 200 kgf/mm
2
or less. Further, in the case that one or a plurality of gap portions for facilitating a shape change are provided in the resin plain bearing, the Young's modulus of the resin may be set to 50 kgf/mm
2
or more and 1500 kgf/mm
2
or less.
Then, the pinch roller apparatus disclosed in the publication mentioned above is structured such that the rotary shaft of the roller main body and the rotary shaft of the capstan are made in parallel to each other due to an elasticity of the resin constituting the plain bearing and the inner peripheral surface of the plain bearing can slide in a state of being nearly in a surface contact with the inclined roller shaft. It is said that accordingly, since the roller shaft and the inner peripheral surface of the plain bearing are not in a point contact state even in a state that the self-aligning function is served, a part of the plain bearing is not abnormally abraded, so that it is possible to sufficiently secure a durability of the pinch roller even in the case of the resin plain bearing.
However, since the pinch roller apparatus described in Japanese Patent Unexamined Publication No. 10-228692 mentioned above is self-aligned in accordance with an elasticity of the resin constituting the plain bearing, there is a risk that the plain bearing generates a fatigue fracture after being used for a long time. Further, since the pinch roller apparatus mentioned above self-aligns in accordance with an elasticity of the resin not with the clearance, much time is required before the pinch roller main body becomes in parallel to the capstan, so that there is a problem that it is impossible to self-align for a short time.
Further, in the pinch roller apparatus described in Japanese Patent Unexamined Publication No. 10-228692 mentioned above, since the elastic operation is different between the gap portion and the non-gap portion in the case of providing a plurality of gap portions in the plain bearing, a bending amount of the plain bearing is different between a time when the inner peripheral surface of the gap portion of the plain bearing is brought into contact with the roller shaft and a time when the inner peripheral surface of the non-gap portion of the plain bearing is brought into contact with the roller shaft, so that there is a risk that a moving operation of the tape becomes uneven. Further, the pinch roller apparatus mentioned above is structured such as to set a contact area between the roller shaft and the plain bearing when pressing the roller main body to the capstan to be great. Accordingly, since an amount of a power consumption of a capstan motor becomes significantly increased, it is not preferably applied to the pinch roller apparatus for a camera integral-type compact video tape recorder and a compact audio tape recorder which are driven by a battery..
The present invention is made by taking the current circumstances into consideration, and an object of the present invention is to provide a pinch roller apparatus having the following objects.
One of the objects of the present invention is to provide a pinch roller apparatus which can stably move a tape in accordance with a sufficient self-aligning function.
Another object of the present invention is to provide an inexpensive pinch roller apparatus as a structure which can easily manufacture a plain bearing.
Further, the other object of the present invention is to provide a pinch roller apparatus in which an assembly of the pinch roller can be easily performed at a time of inserting a pinch roller shaft into a plain bearing pressure fitted to a sleeve so as to assemble the pinch roller.
Still further, the other ob
Kabushiki Kaisha Meiji Gomu Kasei
Mansen Michael R.
Rader & Fishman & Grauer, PLLC
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