JPS5912879A - Platen roller - Google Patents

Abstract

PURPOSE:To lessen the slackening of papers by eliminating the slippage between a platen roller and the paper by providing a charged layer attracting printing papers on the inside of the surface layer of the platen roller. CONSTITUTION:A platen roller 1' is made up by forming a charged layer 1d' of electret as a permanent charging material of polyethylene, etc., between a cylindrical core metal 1b' having shaft 1a' at the center of its both sides and a rubber surface layer 1c' to cover the core metal 1b'. A friction force produced by the pushing pressure between a paper vail roller and a feed roller and a friction force produced from the attraction force of paper to the surface of the roller 1' caused by static electricity of the charged layer 1d' are acted as the friction force between the roller 1' and the paper in such a way as to relieve the moving load of the paper, thereby lessening the slippage and slackening of paper between the paper and the platen roller.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a platen roller, and more particularly to a platen roller for feeding paper used in a paper feeding device such as a typewriter.

Recently, as typewriters have become more sophisticated, typewriters memorize the printed characters, reverse the paper by rotating the platen roller that feeds the paper in the opposite direction, and move the characters printed a few lines ago onto the correction ribbon. It is possible to correct it with tape.

However, Utatoge, which performs such corrections with high printing quality,
Therefore, it is important to match the position of the corrected part of the already printed character with the printing position of the printing means with high precision. .

To achieve this, it is necessary to improve the positional accuracy of the vertical paper feed and the horizontal feed of the carriage.In particular, to increase the positional accuracy of the vertical paper feed, it is necessary to increase the positional accuracy of the paper feed mechanism itself. In addition to the misalignment, it is also necessary that there is no misalignment of the paper due to slip between the platen roller and the paper.

However, the conventional platen roller has the drawback that the above-mentioned slip phenomenon tends to occur. The reason for this will be explained with reference to the figure.

The structure of a conventional paper feeding device equipped with a platen roller is as shown in FIG. In other words, the platen roller 1, which has a cylindrical shape and whose surface is made of rubber or the like, is an old shaft part 1.
A pulley 2 is fixed to a, and a drive belt 3 is stretched between this pulley 2 and a pulley 5 fixed to the output shaft of a pulse motor 4 serving as a drive source. is set to rotate. Further, the paper indicated by the reference numeral 6 is attached to the side surface of the platen roller 1, and is pressed onto the surface of the platen roller 1 by the paper pail roller 7 and feed rollers 8 and 9, and the friction generated by the pressing force The sheet 6 is fed by force in accordance with the amount of rotation of the platen roller 1.

In such a configuration, when the pulse motor 4 is driven and the platen roller 1 rotates in the direction of arrow B in the figure, that is, in the reverse direction for correction (see FIG. 2), the paper 6 and the surface of the platen roller 1 are rotated. The paper 6 tends to move in the direction of arrow C along the surface of the platen roller 1 due to the frictional force generated by the friction coefficient μm between the rollers 7 and 8.9 and the pressing force of each roller 7, 8.9 against the paper 6.

At the same time, each roller 7.8.9 moves in the direction of the arrow due to the frictional force generated by the friction coefficient μ2 between the paper 6 and the surface of each roller 7.8.9 and the pressing force of each roller 7, 8.9. rotated in the direction.

However, there is a rotational load on the bearings (not shown) of the rotating shafts of each roller 7.8.9, and the rotational load and each roller 7.
．． Due to the pressing force of 8.9 and the friction coefficient μ2, a force, that is, a moving load is applied to the paper 6 in the direction of arrow E, which is the opposite direction to the moving direction.

Due to this moving load, the sheet 6 and the platen roller 1 do not move, and the position of the corrected portion of the sheet does not reach the correct position and shifts.

1, the friction coefficient μ2 differs for each roller 7, 8.9, and the moving load for each roller differs, so the slip amount of the paper 6 corresponding to each roller 7, 8, 9 is different, and therefore each A slack a occurs in the paper 6 between the rollers 7, 8, and 9.

As a result, the deviation of the corrected position of the paper from the normal position becomes even larger.

Of course, even when the paper is fed in the opposite direction to the paper feeding direction in the figure, that is, in the direction during normal printing, slipping and sagging of the paper occur in exactly the same way as described above.

Conventionally, as a method to improve the above-mentioned drawbacks, the surface of the platen roller is made rough to increase its friction coefficient, and by increasing the frictional force between the platen roller and the paper, the moving load of the paper is relatively reduced. It has been proposed to prevent the slip phenomenon by reducing the

However, if the surface of the platen roller is made rough, especially when printing on thin paper, the roughness of the surface of the platen roller makes it difficult for the ink from the ink ribbon to transfer to the paper, resulting in a decrease in the quality of printing. This results in the following drawbacks:

The present invention has been made in view of the above circumstances, and provides a platen roller that can suppress the slippage between the platen roller and paper during paper feeding and the sagging of paper without making the surface of the platen roller rough. It is intended to.

In order to achieve this object, the platen roller according to the present invention adopts a structure in which a charged layer that attracts printing paper is formed inside the surface layer of the platen roller.

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 3 shows the structure of a platen roller according to the present invention. The structure of the platen roller, generally indicated by the reference numeral 1, has a shaft portion 1a' at the center of both sides.

Electret (fluorescent material), which is a permanently charged material such as polyethylene, is placed between the cylindrical core metal part 1b' formed with 1a' and the surface layer 1c', which is made of rubber or the like and covers the core metal part 1b'. It has a structure in which a charged layer 1d' is formed from a material such as stone.

The charged layer 1d' attracts the paper attached to the platen roller 1' to the surface of the surface layer 1c' by the static electricity charged therein.

During the paper feeding operation of the paper feeding device using the platen roller 1' having the above structure, in addition to the frictional force generated by the suppression of the paper pail roller and the feed roller, the electrostatic charge of the charged layer 1d' is applied to the surface of the platen roller 1'. The frictional force generated from the adsorption force of the paper acts as a frictional force between the platen roller 1' and the paper 6.

Therefore, the frictional force between the platen roller 1' and the paper becomes greater than when the conventional platen roller 1 described above is used. Therefore, the frictional force between the paper pail roller and the feed roller and the paper plate is relatively small compared to the frictional force between the platen roller 1' and the paper, and the paper moving load due to the paper pail roller and the feed roller is becomes relatively small.

Therefore, the slip phenomenon between the platen roller and the paper and the slack of the paper caused by the moving load can be suppressed to a small level.

As is clear from the above description, the platen roller according to the present invention adopts a structure in which a charged layer made of electret or the like that attracts printing paper is formed inside the surface layer of the roller. The movement load of the paper is reduced in the operation of the paper feeding device used, and the slip phenomenon between the paper and the platen roller due to the movement load and the sag of the paper can be suppressed to a minimum without roughening the surface of the platen roller, resulting in high quality. This method has an excellent effect in that the positional accuracy of paper feeding required for printing, especially correction printing, can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating the structure of a paper feeding device using a conventional platen roller, FIG. 2 is a partially schematic sectional view taken in the direction of arrow A in FIG. FIG. 3 is a partially cutaway perspective view showing the structure of the platen roller according to the present invention. 1'...Platen roller la'...Shaft portion 1b'
...Core part 1c'...Surface layer ld'...
・Charged layer

Claims (2)

[Claims] (1) A platen roller for feeding printing paper provided in a printing paper feeding device of a printing device, characterized in that a charged layer that attracts printing paper is formed inside the surface layer of the platen roller. (2) The platen roller according to claim 1, wherein the charged layer is made of electret. .