JPH0717092A - Printer - Google Patents

Abstract

PURPOSE:To feed a paper without slack and prevent generation of scumming and jam by a printer wherein rotational speed of one feed roller is made lower than that of other feed rollers when a motor rotates normally and is made higher when the motor rotates reversely, and a pressing force between the other rollers is made larger than a pressing force of a pressure roller against the one feed roller. CONSTITUTION:When a platen roller 1 and feed rollers 17 and 7 rotate, a paper 16 is pressed to the rollers 17 and 7 by pressure rollers 8 and 9, so that it is sent to the left side by frictional force. At this time, a pressing force F2 of a spring 27 which presses the roller 9 to the roller 7 is larger than a pressing force F1 of a plate spring 26 which presses the roller 8 to the roller 17, and the rotational speed of the roller 17 is made lower than that of the roller 7. Accordingly, the paper 16 is conveyed with the rotation of the roller 7 and a predetermined tension is given to the paper 16 between the rollers 17 and 7 in accordance with speed difference between the rollers 7 and 17, so that the paper 16 is conveyed without generating slack and is printed by a print head 2 on the platen 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer in which a feed roller is arranged in front of and behind a printing unit and a feed sheet is fed by the feed roller in either a forward direction or a reverse direction for printing. .

[0002]

2. Description of the Related Art FIG. 4 is a schematic side view showing a conventional printer of this type, and here, a horizontal printer is illustrated. In the drawing, 1 is a platen rotatably supported by a frame (not shown), 2 is a print head disposed on the platen 1 with its tip facing the platen 1, and the print head 2 is arranged so as to be parallel to the platen 1. It is mounted on a carriage (not shown) attached to a guide shaft fixed to the frame, and reciprocates along the platen 1 integrally with the carriage by a space mechanism (not shown).

Reference numeral 3 is a platen pulley coaxially attached to one end of the platen 1, reference numeral 4 is a motor, and reference numeral 5 is a drive pulley attached to a rotating shaft of the motor 4. 6
Reference numerals 7 and 7 denote feed rollers arranged in front of and behind the printing portion constituted by the platen 1 and the print head 2, reference numerals 8 and 9 denote pressure rollers arranged on the feed rollers 6 and 7, and these rollers 6 to 9 are It is rotatably supported by the frame.

Reference numeral 10 is a leaf spring as an urging means for urging the pressure roller 8, and 11 is a leaf spring as an urging means for urging the pressure roller 9.
The pressure rollers 8 and 9 are pressed against the feed rollers 6 and 7 with the same pressing force F by 0 and 11, respectively. 12 and 13 are driven pulleys that are coaxially attached to one ends of the feed rollers 6 and 7, 14 and 15 are synchro belts, and one synchro belt 14 is wound around the platen pulley 3 and the drive pulley 5 and One of the synchro belts 15 has the driven pulleys 12, 1
3 and another drive pulley (not shown) provided coaxially with the drive pulley 5, so that when the motor 4 rotates, the platen 1 and the feed rollers 6 and 7 follow solid arrows according to the rotation direction. It rotates in the counterclockwise direction (forward direction) indicated by or the clockwise direction (reverse direction) indicated by a dashed arrow.

Reference numeral 16 is a sheet. Next, the operation of the above configuration will be described. Paper 16 with platen 1 and print head 2
The sheet 1 in the state of being sandwiched between the feed rollers 6 and 7 and the pressure rollers 8 and 9 by being passed between
When 6 is sent from right to left for printing, the motor 4 is rotated counterclockwise.

The rotational force of the motor 4 is driven by the drive pulley 5,
Since it is transmitted to the platen 1 through the synchro belt 12 and the platen pulley 3, the platen 1 rotates counterclockwise as indicated by the solid arrow, and at the same time, the rotational force of the motor 4 is provided coaxially with the drive pulley 5. Since it is also transmitted to the feed rollers 6 and 7 via another drive pulley, the synchro belt 13 and the driven pulleys 12 and 13, the feed rollers 6 and 7 are also counterclockwise indicated by solid arrows at the same speed. Rotate.

At this time, since the paper 16 is pressed against the feed rollers 6 and 7 by the pressure rollers 8 and 9, the paper 16 is fed to the left by the frictional force and printed by the print head 2 on the platen 1. It Conversely, when the paper 16 is fed from left to right for printing, rotating the motor 4 in the clockwise direction transmits the rotational force in the same manner as described above, so the platen 1 is indicated by the dashed arrow. At the same time as the feed rollers 6 and 7 rotate clockwise, the feed rollers 6 and 7 also rotate at the same speed in the clockwise direction indicated by the dashed arrow, whereby the paper 16 is fed rightward and printed by the print head 2 on the platen 1.

[0008]

However, in the above-mentioned conventional printer, since the pressing force of each pressure roller against the feed roller before and after the printing portion is equal and each feed roller rotates at the same speed, the feed rollers are rotated. If there is slack in the paper between
There is a problem in that the slack cannot be removed, and therefore, the print stain is generated in the slack portion, and the slack causes a jam or the like.

The present invention has been made in order to solve such a problem, and the paper is fed between the feed rollers before and after the printing portion without causing slack to prevent the occurrence of print stains and jams. It is an object of the present invention to realize a printer that can be prevented.

[0010]

To achieve this object, according to the present invention, a feed roller is arranged in front of and behind a printing portion constituted by a platen and a print head facing the platen, and both feed rollers are provided. The pressure rollers biased by the biasing means are opposed to each other, the sheet passed between the platen and the print head is pressed against the feed rollers by the pressure rollers, and the feed rollers are driven by the same motor. A printer in which the paper is fed in the forward direction or the reverse direction by rotating or reversely rotating to perform printing by the print head,
And two planetary gears, one planetary gear reduces the rotational speed of one of the feed rollers with respect to the other feed roller when the motor rotates forward, and the other when the motor rotates in the reverse direction. A planetary gear mechanism for increasing the rotation speed of the one feed roller with respect to the other feed roller by the planet gear is provided between the one feed roller and the motor, and one of the feed rollers is provided with one planetary gear mechanism. The pressing force of the biasing means for pressing the other pressure roller against the other feed roller is larger than the pressing force of the biasing means for pressing the pressure roller.

[0011]

According to the present invention having such a configuration, when the paper passed between the platen and the print head is pressed against both the feed rollers by the pressure rollers and the motor is rotated in the forward direction, the both feed rollers are rotated. Rotates forward, but at this time, the rotation speed of the one feed roller is reduced by one planetary gear of the planetary gear mechanism with respect to the other feed roller, and one pressure roller is pressed against the one feed roller. Since the pressing force of the biasing unit that presses the other pressure roller against the other feed roller is large with respect to the pressing force of the biasing unit, the paper is fed according to the rotation of the other feed roller, and due to the rotational speed difference between the two feed rollers. Because the paper is tensioned, the paper is fed without sagging.

On the contrary, when the motor is reversely rotated, both feed rollers are also reversely rotated, and at this time, the rotation speed of the one feed roller is changed by the other planet gear of the planetary gear mechanism. However, since the pressing force of the biasing means that presses the other pressure roller against the other feed roller is greater than the pressing force of the biasing means that presses the one pressure roller against the one feed roller, In this case as well, the paper is fed in accordance with the rotation of the other feed roller, and tension is applied to the paper by the difference in the rotational speeds of the two feed rollers, so the paper is fed without sagging.

Therefore, according to this, even when the feed roller is rotated in either the normal direction or the reverse direction, the sheet can be fed without causing slack, and the print stain or jam caused by the slack in the sheet can be performed. It is possible to prevent the occurrence of such problems, and since the paper is fed in accordance with the rotation of the other roller, the paper feed amount is constant regardless of whether the paper is rotated in the forward direction or the reverse direction, which is suitable for printing. It becomes a thing.

[0014]

[Examples] Examples will be described below with reference to the drawings. FIG. 1 is a schematic side view showing an embodiment of a printer according to the present invention, and FIGS. 2 and 3 are enlarged side views of essential parts showing the operation of the embodiment of FIG. In the figure, 1 is a platen, 2 is a print head, 3 is a platen pulley, 4 is a motor, 5 is a drive pulley, 7 is a feed roller, 8 and 9 are pressure rollers, 13 is a driven pulley, 14 is a synchro belt, 16
Is a sheet of paper, which corresponds to the conventional one shown in FIG.
Since they are arranged similarly, the same reference numerals are given and the description thereof is omitted.

A feed roller 17 is arranged below the pressure roller 8. A feed gear 18 is attached to one end of the feed roller 22. 19-24
Is a component of the planetary gear mechanism, 19 is a driven pulley rotatably supported by a frame (not shown), and a transmission gear 20 is provided coaxially with the driven pulley 19.

A center portion of a lever 22 formed in a V shape, that is, a corner portion of the V shape is swingably attached to a rotation fulcrum 21 of the driven pulley 19 via a friction spring (not shown). The planetary gears 23 and 24 meshing with the driven gear 18 by the swinging of the gear 22 are rotatably supported at both ends of the lever 22.
Each of the four gears 4 always meshes with the transmission gear 20, but the opening angles of the V-shaped levers 19 are set so that the planetary gears 23 and 24 do not mesh with each other apart from each other.

Here, the planetary gear 24 is composed of two gears 24a and 24 which are coaxially fixed as shown in FIGS.
The gear 24 having the smaller diameter
The gear 24a, which has a larger diameter, always meshes with the transmission gear 20, and the gear 24b, which has a larger diameter, meshes with the driven gear 18 when the lever 22 swings clockwise. Reference numeral 25 denotes a synchro belt, which is wound around another drive pulley (not shown) provided coaxially with the drive pulley 5 and the driven pulleys 13 and 19, and when the motor 4 is rotated by this, the rotation direction thereof. Accordingly, the feed roller 7 rotates, and the driven gear 18 of the feed roller 17 meshes with the planet gear 23 or the gear 24b of the planet gear 24 to rotate the feed roller 17. Here, the driven gear 18 is rotated by the planet gear. When 23 meshes and rotates, the feed roller 17 is decelerated with respect to the feed roller 7, and when the gear 24b of the planetary gear 24 meshes with the driven gear 18 and rotates, the feed roller 17 accelerates with respect to the feed roller 7. As described above, the gear ratios of the gears 24a and 24b forming the planetary gear 23 and the planetary gear 24 are It is constant.

Reference numeral 26 is a leaf spring as an urging means for urging the pressure roller 8, 27 is a leaf spring as an urging means for urging the pressure roller 9, and the pressure roller 8 is pressed by the leaf spring 26. The pressure roller 9 is pressed against the feed roller 17 by F1, and the pressure roller 9 is pressed against the feed roller 7 by a pressing force F2 by the leaf spring 27. The pressing forces F1 and F2 have a relationship of “F1 <F2”. It is set.

Next, the operation of the above configuration will be described. The paper 16 is passed between the platen 1 and the print head 2 to feed rollers 17, 7 and pressure rollers 8, 9
When the paper 16 is fed from the right to the left in the state of being sandwiched between and, the motor 4 is rotated counterclockwise. Since the rotational force of the motor 4 is transmitted to the platen 1 via the drive pulley 5, the synchro belt 12 and the platen pulley 3, the platen 1 rotates counterclockwise, and at the same time, the rotational force of the motor 4 is It is transmitted to the feed roller 7 via another drive pulley provided coaxially with the drive pulley 5, the synchronizing belt 25, and the driven pulley 13, whereby the feed roller 7 rotates counterclockwise.

Further, the rotating force is the synchronizing belt 2
It is also transmitted to the driven pulley 19 via 5. As a result, the transmission gear 20 rotates counterclockwise, the lever 22 swings counterclockwise by the action of a friction spring (not shown), and the planet gear 23 meshes with the driven gear 18, so that the synchro belt 25 is driven by the driven pulley. The counterclockwise rotational force transmitted to 19 is transmitted to the feed roller 17 via the transmission gear 20, the planetary gear 23, and the driven gear 18, so that the feed roller 17 also rotates in the counterclockwise direction.

When the platen 1 and the feed rollers 17 and 7 rotate in this way, the paper 16 is pressed against the feed rollers 17 and 7 by the pressure rollers 8 and 9, and therefore the paper 16 is fed to the left by the frictional force. At this time, the pressure roller 8 is replaced by the feed roller 1
The pressing force F2 of the plate spring 27 pressing the pressure roller 9 against the feed roller 7 is larger than the pressing force F1 of the plate spring 26 pressing against the feed roller 7, and the rotation speed of the feed roller 17 is higher than that of the feed roller 7.
Since the paper 16 is decelerated with respect to the rotation speed of the feed roller 7, the paper 16 is sent in accordance with the rotation of the feed roller 7, and the paper 16 is fed between the feed rollers 17 and 7 by a predetermined difference due to the difference in the rotation speed of the feed rollers 7 and 17. Is given tension,
Therefore, the paper 16 is fed and printed by the print head 2 on the platen 1 without causing slack.

The paper 16 is inserted between the feed rollers 17 and 7.
Even if a tension is generated on the sheet 16, the sheet 16 slips between the feed roller 17 and the sheet 16, so that the sheet 16 can be fed without any trouble. Conversely, when the paper 16 is fed from left to right for printing, the motor 4 is rotated in the clockwise direction, and the rotational force is transmitted to the platen 1 and the feed roller 7 in the same manner as described above. 1 and the feed roller 7 rotate clockwise.

At the same time, the rotational force of the motor 4 is also transmitted to the driven pulley 19 via the synchro belt 25 as described above. As a result, the transmission gear 20 rotates clockwise, and the lever 22 swings clockwise due to the action of a friction spring (not shown) so that the gear 24 of the planetary gear 24 is rotated.
Since b is engaged with the driven gear 18, the clockwise rotational force transmitted from the synchro belt 25 to the driven pulley 19 is transmitted by the transmission gear 20, the gear 24a of the planetary gear 24, and the gear 2.
It is transmitted to the feed roller 17 via 4b and the driven gear 18, so that the feed roller 17 also rotates in the clockwise direction.

When the platen 1 and the feed rollers 17 and 7 are thus rotated, the paper 16 is pressed against the feed rollers 17 and 7 by the pressure rollers 8 and 9, and the paper 16 is fed rightward by the frictional force. To be In this case, the rotation speed of the feed roller 17 is increased with respect to the rotation speed of the feed roller 7, but the pressure roller 9 is stronger than the pressing force F1 of the leaf spring 26 pressing the pressure roller 8 against the feed roller 17. Leaf spring 27 pressing the feed roller 7 against
Since the pressing force F2 of is larger than the above, the paper 16 is fed in accordance with the rotation of the feed roller 7 in the same manner as described above, and the speed difference between the rotations of the feed rollers 7 and 17 causes the paper 16 to move between the feed rollers 17 and 7. A predetermined tension is applied, so that the paper 16 is fed and printed by the print head 2 on the platen 1 without causing slack.

In this case as well, the feed rollers 17, 7
When tension is applied to the sheet 16 between the sheets 16, the sheet 16 slips between the feed roller 17 and the sheet 1 does not interfere.
6 is sent, and moreover, the paper 16 is sent in accordance with the rotation of the feed roller 7 as in the normal rotation, so that the feed amount is the same as in the normal rotation. Although the leaf springs 26 and 27 are used as the urging means for pressing the pressure rollers 8 and 9 against the feed rollers 17 and 7 in the above-described embodiments, the present invention is not limited to this, and coil springs or the like may be used. Of course, you can do that.

Further, although the platen 1 is rotated by the motor 4 in the above-mentioned embodiment, it is applicable to a printer using a fixed platen.

[0027]

As described above, the present invention has two planetary gears, and one of the two feed rollers arranged before and after the printing section by one planetary gear when the motor rotates forward. The planetary gear mechanism that reduces the rotational speed of the one feed roller to the other feed roller and increases the rotational speed of the one feed roller with respect to the other feed roller by the other planet gear when the motor rotates in the reverse direction. Of the urging means that presses the other pressure roller against the other feed roller against the pressing force of the urging means that presses the one pressure roller against the one feed roller while being provided between the feed roller and the motor. Since the pressing force is configured to be large, when the feed roller is rotated in either the forward or reverse direction, However, it is possible to feed the paper without causing slack in the paper, and it is possible to prevent the occurrence of print stains or jams due to the slack in the paper, and the paper can be fed by the other roller. Since the paper is fed in accordance with the rotation, there is an advantage that the paper feed amount becomes constant regardless of whether the paper is rotated in the forward direction or the reverse direction, which is suitable for printing.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of a printer according to the present invention.

FIG. 2 is an enlarged side view of an essential part showing the operation of the embodiment of FIG.

FIG. 3 is an enlarged side view of an essential part showing the operation of the embodiment of FIG.

FIG. 4 is a schematic side view showing a conventional printer.

[Explanation of symbols]

 1: Platen 2: Print Head 3: Platen Pulley 4: Motor 5: Drive Pulley 7: Feed Roller 8, 9: Pressure Roller 13: Driven Pulley 14: Synchronous Belt, 16: Paper 17: Feed Roller 18: Driven Gear 19: Driven pulley 20: Transmission gear 22: Lever 23, 24: Planetary gear 25: Synchro belt 26, 27: Leaf spring

Claims (1)

[Claims] 1. A feed roller is arranged in front of and behind a printing portion composed of a platen and a print head facing the platen, and pressure rollers biased by biasing means are opposed to both feed rollers, respectively. The paper passed between the platen and the print head is pressed against the feed rollers by the pressure rollers, and the feed rollers are rotated forward or backward by the same motor to rotate the paper forward or backward. In the printer for performing printing by the print head by sending to one of the two feed rollers, the rotation speed of one feed roller of the two feed rollers is changed by the other planet gear when the motor rotates forward. The speed is reduced with respect to the roller, and when the motor rotates in the reverse direction, the other planetary gear causes A planetary gear mechanism for increasing the rotation speed of the feed roller with respect to the other feed roller is provided between the one feed roller and the motor, and a biasing means for pressing one pressure roller against the one feed roller is provided. A printer characterized in that the pressing force of a biasing means for pressing the other pressure roller against the other feed roller is increased with respect to the pressing force.