JPH05309902A - Serial printer - Google Patents

Abstract

PURPOSE:To obtain a print image of high quality, by preventing the displacement of the forward and backward printing positions of a printing head from each other. CONSTITUTION:An endless toothed belt 21 is stretched between a pair of toothed pulleyes 19 and 20. An ink jet head 16 is fixed to part of the toothed belt 21 via a support 15. Printing is carried out on a sheet of recording paper P by turning the toothed belt 21 by means of the normal/reverse rotation of a shifting motor 18 connected to the one toothed pulley 19, thereby reciprocating the ink jet head 16. The tension of the toothed belt 21 is set to the 3.5-6.5kg range (the optimum range is 4-6kg). This range obviates slack in the toothed belt 21 and effect on the rotation of the shifting motor 18 and, within this range, the ink jet head 16 on the toothed belt 21 is accurately moved following the rotation of the shifting motor 18, therefore the displacement of the forward and backward printing positions of the head 16 from each other is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer which prints on paper while reciprocally moving a print head in a printing line direction, and more particularly to a belt for reciprocating the print head.

[0002]

2. Description of the Related Art In a serial printer of this type, for example, an ink jet printer, an endless toothed belt is mounted between a pair of toothed pulleys, and an ink jet head is fixed to a part of the toothed belt. .. A drive motor is connected to one toothed pulley, and the toothed belt is rotated through the toothed pulley by the forward and reverse rotations of the drive motor. Then, while the inkjet head is reciprocatingly moved in the print row direction (main scanning direction) along with the circulation of the toothed belt, ink is ejected from the nozzles provided in the head to print on the paper. Is becoming

[0003]

However, in the conventional ink jet printer described above, a deviation occurs between the print position on the forward path and the print position on the return path of the inkjet head.

And, as a factor causing the deviation,
Backlash or the like that occurs between the toothed pulley and the toothed belt is conceivable. However, according to the experiments conducted by the inventors, the set tension of the toothed belt mounted between the toothed pulleys has a large relationship. There was found.

Therefore, it is necessary to mount the toothed belt between the toothed pulleys with a tension such that the deviation of the printing position between the forward and backward passes of the ink jet head is minimized. Belt tension is almost 50
It was set in the range of 0 to 700 g. According to the measurement by the inventors, when the tension of the toothed belt is set to the above value, the deviation between the forward path and the return path is 100 μm.
It was as high as ~ 1 mm.

The cause of this deviation is that the tension of the toothed belt is weak and the toothed belt is loosened, so that the ink jet head on the toothed belt is not accurately moved following the rotation of the drive motor. That is, at the start of traveling on the outward path and the return path, even if the driving force is transmitted to the toothed pulley, the looseness of the toothed belt is first absorbed and then the inkjet head starts to move. This movement delay of the inkjet head causes the above-mentioned deviation.

An object of the present invention is to provide a serial printer which can eliminate the deviation of the printing position between the forward and backward passes of the print head and can obtain a high quality printed image.

[0008]

In order to achieve the above object, according to the present invention, an endless belt is mounted between a pair of pulleys, a print head is fixed to a part of the belt, and the pulley is attached to the pulley. In a serial printer that prints on paper by reciprocally moving a print head by orbiting a belt by forward and reverse rotation of a connected motor, the tension of the belt does not relax and the rotation of the motor It is set within the range that does not affect the.

[0009]

Therefore, according to the present invention, the tension of the belt is set within the range in which the belt does not loosen and does not affect the rotation of the motor. If the belt is mounted between both pulleys so that the tension is within this range, the print head on the belt moves accurately following the rotation of the motor, and the print position shifts between the forward and return passes of the print head. Becomes very small.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the serial printer of the present invention is embodied as an ink jet printer will be described below with reference to the drawings.

As shown in FIGS. 1 to 3, a paper feed cassette 2 is removably attached to the lower part of one side of the apparatus case 1. The paper feed cassette 2 is formed in a substantially box shape with an open upper surface, and a large number of recording papers P as papers are accommodated inside in a stacked state. The push-up plate 3 is the paper feed cassette 2
It is rotatably attached to the inner side of and is biased upward by a spring 4.

A pair of support plates 5 are arranged inside the apparatus case 1 so as to be located on both sides of the paper feed cassette 2, and both support plates 5 are located above the end of the paper feed cassette 2 on the paper delivery side. A rotary shaft 6 is rotatably supported between them. The pair of paper feed rollers 7 are supported by the rotating shaft 6 so as to be rotatable integrally with each other, and the recording paper P in the paper feed cassette 2 is moved by the push-up plate 3.
It is pushed up by and is brought into contact with the paper feed roller 7.

A pulley 8 is attached to one end of the rotary shaft 6, and the rotation of the paper feeding motor 13 is transmitted to the pulley 8 via a belt 9, a pulley 10 and gears 11 and 12. Is becoming By the rotation of the drive motor 13, the paper feed roller 7 is rotated together with the rotary shaft 6, and the recording papers P in the paper feed cassette 2 are sent out one by one.

A pair of guide rods 14 are supported in parallel with each other between the support plates 5, and a support member 15 is reciprocally movable along the guide rods 14 along the rods 14 in the printing direction (main scanning direction). Supported by. An inkjet head 16 as a print head is fixed to a support body 15, and a plurality of nozzles 17 are arranged in series on the front surface of the support body 15 at predetermined intervals in the print row direction (sub-scanning direction).

A moving motor 18 composed of a stepping motor is fixed to one support plate 5, and a toothed pulley 19 is attached to its drive shaft. Also, the other support plate 5
A toothed pulley 20 is rotatably supported by the toothed pulley 20, and an endless toothed belt 21 is mounted between the toothed pulley 20 and the toothed pulley 19. A predetermined tension described later is applied to the toothed belt 21, and the belt 21 is mounted so as to extend in parallel along the guide rod 14. In this embodiment, a predetermined tension is applied to the toothed belt 21 by setting the axial distance between the toothed pulleys 19 and 20. The support 15 is connected to a part of the outer peripheral surface of the toothed belt 21, and the toothed belt 2 is passed through the toothed pulley 19 by the forward / reverse rotation of the moving motor 18.
When 1 is rotated, the support 15 and the inkjet head 16 are reciprocated along the guide rod 14.

The guide plate 22 is arranged so as to face the nozzle surface of the ink jet head 16 at a predetermined interval, and the recording paper P sent out from the paper feed cassette 2 is guided on the guide plate 22. The pair of rotary shafts 23, 24 are rotatably supported between the support plates 5 so as to extend in parallel along the guide rod 14, and are arranged on the paper feed side and the paper feed side of the inkjet head 16, respectively. .. The plurality of feed rollers 25 and 26 are supported by the rotary shafts 23 and 24 so as to be integrally rotatable, respectively.

Pulleys 27 and 28 are attached to one ends of the rotary shafts 23 and 24, respectively.
The rotation of the transfer motor 33 is transmitted to the motor 8 via a belt 29, a pulley 30, and gears 31 and 32. Incidentally, 34 is a tension roller. The gear-shaped roller 35 is arranged so as to face the feed roller 26 provided on the paper feed side of the inkjet head 16, and is driven to rotate as the feed roller 26 rotates.

Then, by the rotation of the transfer motor 33,
The feed rollers 25 and 26 are rotated together with the rotary shafts 23 and 24, and the recording paper P guided on the guide plate 22 is
The feed rollers 25, 26 and the gear-shaped roller 35 are rotated to transfer them in the print row direction. Then, while the recording paper P is supported on the guide plate 22, ink is ejected from each nozzle 17 while the inkjet head 16 is reciprocatingly moved in the print row direction, and printing is performed on the recording paper P with a dot matrix. Is done. The recording paper P after printing is discharged onto the paper discharge tray 36 by the rotation of the feed roller 26 and the gear-shaped roller 35.

As shown in FIG. 4, the toothed belt 21
Is configured by covering a large number of core wires 21a made of glass fiber with an outer cover 21b made of chloroprene rubber. With the above structure, the toothed belt 21 is strong against bending fatigue, excellent in abrasion resistance and weather resistance, and has high tensile strength and extremely little elongation. In this embodiment, the toothed belt 21 having a width H of 8 mm is used.

In this embodiment, the toothed pulley 1 is also used.
The number of teeth of the teeth 9 and 20 is 25, and the axial distance between the toothed pulleys 19 and 20 is approximately 400 mm. Further, in this embodiment, a motor having a speed-torque characteristic as shown in FIG. 5 is used as the moving motor 18, and the number of rotations in the printing operation of this embodiment is 6
It is set to 00 rpm.

In this embodiment, the toothed belt 21 has a tension in the range of 3.5 to 6.5 kg (the optimum range is 4).
It is mounted between the toothed pulleys 19 and 20 so that the weight is about 6 kg. It should be noted that the moving motor 18 may be any motor as long as it generates a torque to the extent that the rotational speed or the like is not affected by the load due to the tension of the toothed belt 21. Also, the toothed belt 21 itself, of course,
Any material may be used as long as it has such a strength that elongation or the like does not occur due to the tension within the set range.

Then, as described above, the tension of the toothed belt 21 is in the range of 3.5 to 6.5 kg (the optimum range is 4 to 6 k).
It has been proved by the experiments of the inventors that the deviation of the printing position between the forward path and the backward path of the inkjet head 16 is minimized when the setting is set to g).

Here, the experimental method will be described. As shown in FIG. 6, a plurality of straight lines extending in the print row direction are formed on the recording paper P by an apparatus using a toothed belt 21 having a width H of 8 mm. To print. Then, the printing is performed by changing the tension of the toothed belt 21 to a plurality of values. Then, based on the printing results corresponding to the respective tension values, the deviation amount Δ of the printing position between the forward path and the backward path of the inkjet head 16 was measured. The deviation amount Δ was measured for each of the three straight lines at the left end, the center, and the right end on the recording paper P.

The measurement results of the above experiment are shown in the table of FIG. In the figure, the deviation amount Δ on the + side represents the case where the printing position on the return path deviates to the left side in FIG. The case where the print position on the return path is shifted to the right side is shown. Then, as is clear from FIG. 7, when the tension of the toothed belt 21 is set in the range of 3.5 to 6.5 kg (the optimum range is 4 to 6 kg), the shift amount Δ may be the smallest. I understand.

Incidentally, FIGS. 8 to 10 and the reference photograph a,
In b and c, the tension of the toothed belt 21 is 0.88 k, respectively.
FIG. 9 is a magnified view or photograph of approximately 19/3 times showing a printing result when g, 4.56 kg, and 8.40 kg are set, showing a part of a straight line printed on the right end side of the recording paper P. is there. 8 to 10 and the reference photograph a,
As is clear from comparison between b and c, when the tension of the toothed belt 21 is set to 0.88 kg or 8.40 kg, the deviation between the forward pass and the return pass is set when 4.56 kg is set. It is easy to understand that is small.

That is, the tension of the toothed belt 21 is 3.5 to
If the setting is made smaller than the range of 6.5 kg, the tension is weak and the toothed belt 21 is loosened, so that the inkjet head 16 on the toothed belt 21 is not accurately moved following the rotation of the moving motor 18, Misalignment occurs.
Further, when the tension of the toothed belt 21 is set in the range of 3.5 to 6.5 kg (the optimum range is 4 to 6 kg), the inkjet head 16 on the toothed belt 21 is moved in accordance with the rotation of the moving motor 18. Since it can be moved accurately, the deviation can be reduced. If the tension of the toothed belt 21 is set to be larger than the range of 3.5 to 6.5 kg,
A shift occurs due to a change in the rotational speed of the moving motor 18 or the like due to the load due to the tension of the toothed belt 21 or the elongation of the toothed belt 21 itself.

The tension of the toothed belt 21 is 3.5 to 6.
When it is set larger than the range of 5 kg, it is conceivable to use a moving motor having a torque large enough to withstand the load due to the large tension, or to use a tooth belt with higher tensile strength. If it is set, the manufacturing cost will increase. Therefore, the toothed belt 2 is used as the moving motor 18 and the toothed belt 21.
It is best to use one that does not cause a problem when the tension of No. 1 is set in the range of 3.5 to 6.5 kg, considering both the problem of deviation and the problem of manufacturing cost. is there.

As described above, in this embodiment, the tension of the toothed belt 21 is compared with the tension of the toothed belt in the conventional apparatus in the range of 3.5 to 6.5 kg (the optimum range is 4
The deviation of the printing position between the forward path and the backward path of the inkjet head 16 can be made very small by setting a large value of up to 6 kg), and a high quality printed image can be obtained. Moreover, the above effect can be obtained with a very simple configuration in which the tension of the toothed belt 21 is simply increased without complicated control.

The present invention is not limited to the above-described embodiment. For example, the toothed belt 21 having a different width H may be used, the rotational speed of the moving motor 18 may be changed, or the toothed belt 21 may be toothed. The pulleys 19 and 20 having different numbers of teeth may be used, the axial distance between the pulleys 19 and 20 may be changed, and the pulleys may be embodied in a serial printer other than an inkjet printer, such as a thermal head printer. The configurations of the respective units can be arbitrarily modified and embodied without departing from the spirit of the invention.

[0030]

As described above in detail, according to the present invention, it is possible to eliminate the deviation of the print position between the forward and backward passes of the print head, and it is possible to obtain a high quality printed image. Demonstrate.

[Brief description of drawings]

FIG. 1 is a plan sectional view showing an embodiment in which a serial printer of the present invention is embodied as an inkjet printer.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG. 4 is a partially enlarged perspective view showing a toothed belt and a toothed pulley.

FIG. 5 is a table showing speed-torque characteristics of a moving motor.

FIG. 6 is an explanatory diagram showing an experimental method for measuring a shift amount.

FIG. 7 is a table showing the measurement results of the experiment.

FIG. 8 is an enlarged view showing a printing result when the tension of the toothed belt is set to 0.88 kg.

FIG. 9 is an enlarged view showing a printing result when the tension of the toothed belt is set to 4.56 kg.

FIG. 10 is an enlarged view showing a printing result when the tension of the toothed belt is set to 8.40 kg.

[Explanation of symbols]

16 ... Inkjet head as print head, 18
... moving motor, 19 ... toothed pulley, 20 ... toothed pulley, 21 ... toothed belt, P ... recording paper as paper.

Claims (1)

[Claims] 1. An endless belt is mounted between a pair of pulleys, a print head is fixed to a part of the belt, and the belt is rotated by forward and reverse rotations of a motor connected to the pulleys. In a serial printer that prints on paper by reciprocally moving a print head, the tension of the belt is set within a range in which the belt does not loosen and does not affect the rotation of the motor.