JPH11138935A - Carriage driving mechanism for serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carriage driving mechanism without jitter by suppressing a vibration of the carriage in a serial printer and without transmission error in the case of reversing the carriage. SOLUTION: Toothforms of a toothed belt 22 and a driving pulley 24 coupled to a carriage 23 are formed helical, and the relationship between a width size (W) of the belt 22 and a width size (W') of the pulley 24 is set to W'-W<=0.5 mm. Then, a meshing vibration of the belt 22 with the pulley 24 is reduced, and a moving amount of the belt 22 in a width direction of feeding the belt 22 is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carriage driving mechanism of a serial printer which has a recording head mounted on the serial printer and drives a carriage which reciprocates along a platen. In particular, the driving force of a driving motor is smoothly applied to the carriage. The present invention relates to a carriage driving mechanism of a serial printer which can transmit the data to a carriage.

[0002]

2. Description of the Related Art In general, a serial printer, which drives a toothed belt wound around a driven pulley and a driving pulley to move a carriage on which a recording head is mounted, is widely used as an output device such as a computer or a word processor. Have been.

FIGS. 6 and 7 show an example of a carriage driving mechanism 1 of such a serial printer. The carriage driving mechanism 1 is mounted at a position outside a moving range of a carriage 3 on which a recording head is mounted, at a predetermined interval. A pulley 4 and a driven pulley 6 are provided, and the toothed belt 2 wound around the driving pulley 4 and the driven pulley 6 is driven by a driving motor 10 including a stepping motor, so that the toothed belt 2 is The connected carriage 3 moves left and right. The driving pulley 4 is fixedly provided, and the driven pulley 6 is provided with the toothed belt 2.
Is attached to the printer body via a tension spring 5 to apply tension to the printer body.

A drive gear 7 that rotates integrally with the drive pulley 4 is connected to a lower end surface of the drive pulley 4. The drive pulley 4 and the drive gear 7 are rotatably supported by a small-diameter portion of a support shaft 8 formed to have a step so that the upper end has a small diameter. Further, the drive pulley 4 and the drive gear 7 supported by the support shaft 8
Is positioned in the axial direction by an end face connecting the small-diameter part and the large-diameter part of the support shaft 8 and a retaining ring 9 disposed near the end face of the small-diameter part of the support shaft 8. Also,
An output gear 11 fixed to an output shaft 10a of a drive motor 10 meshes with the drive gear 7.

According to the carriage driving mechanism 1 of the serial printer configured as described above, the driving motor 1
0, the toothed belt 2 is rotated forward and reverse via the output gear 11, the drive gear 7, and the drive pulley 4 to reciprocate the carriage 3 in the left-right direction shown by the double-headed arrow direction A in FIG. It is designed to be moved.

[0006]

By the way, in a serial printer, a carriage 3 having a recording head is mounted.
In some cases, the shading may cause shading uneven in the direction (vertical direction) perpendicular to the moving direction of the carriage 3, which is called jitter, and solving this shading unevenness is an important issue for obtaining high-quality recording. It is one. Therefore, in order to reduce the vibration of the carriage 3 due to the meshing vibration between the toothed belt 2 and the driving pulley 4, it is effective to make the toothed belt 2 and the driving pulley 4 have a helical shape. In some serial printers, such a helical toothed belt 2 is used.

However, when the toothed belt 2 and the driving pulley 4 have a helical profile, a thrust force is generated by the driving of the toothed belt 2. The phenomenon that the belt 2 moves in the width direction of the driving pulley 4 occurs. For example, when the drive pulley 4 is rotated so that the toothed belt 2 moves in the direction of arrow B,
A thrust force acts to move the toothed belt 2 in the direction of arrow b. On the other hand, when the drive pulley 4 rotates so that the toothed belt 2 moves in the direction of arrow C, the thrust moves the toothed belt 2 in the direction of arrow c. The force works (see FIG. 8).

As described above, every time the running direction of the toothed belt 2 that is equal to the moving direction of the carriage 3 reverses, the toothed belt 2 moves in the width direction of the driving pulley 4 to cause a transmission error. If the error is large, the printing position shifts in the serial printer, and a high-quality recorded image cannot be obtained. The amount of movement in the thrust direction depends on the width (W ′) of the driving pulley 4 and the toothed belt 2.
Becomes larger as the difference (play) from the width dimension (W) of the first lens becomes larger, and the transmission error also has a correlation with this difference.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to smoothly transmit the driving force of a driving motor to a carriage and to reduce the movement of a toothed belt in the width direction of a driving pulley. Accordingly, it is an object of the present invention to provide a carriage driving mechanism of a serial printer capable of reducing a transmission error and obtaining a high-quality recorded image without a printing position shift.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a serial driving device for a serial printer according to the present invention is characterized in that a toothed belt connected to a carriage and a toothed belt are connected. Each tooth profile of the driving pulley is made helical, and the relationship between the width dimension (W) of the toothed belt and the width dimension (W ') of the driving pulley is set such that W'-W≤0.5 mm. It is in. By adopting such a configuration, the meshing vibration between the toothed belt and the driving pulley can be reduced, and the amount of movement of the toothed belt in the width direction during traveling can be reduced.

A feature of the carriage driving mechanism of the serial printer according to the present invention is that the helical twist angle (θ) of the toothed belt is set to 7 ° to 12 °. By adopting such a configuration, the maximum transmission error e during the running of the toothed belt is further reduced to e = 0.
The value can be as small as 5 × tan θ = 0.106 mm, but this value is the amount absorbed in the acceleration region from the reversal of the running direction of the toothed belt to the start of recording.

[0012]

1 and 2 show a main part of a carriage driving mechanism of a serial printer according to an embodiment of the present invention. FIG. 1 is a perspective view of the carriage driving mechanism, and FIG. FIG.

As shown in FIGS. 1 and 2, the carriage driving mechanism 21 of the serial printer according to the present embodiment has a toothed belt 22 called a timing belt.
The toothed belt 22 is driven by a drive pulley 24 and a tension spring 25 fixedly provided at a predetermined distance from a position outside the moving range of the carriage 23.
A carriage 23 slidably attached to a drive shaft 27 is fixedly attached to a part of the toothed belt 22 so as to be stretched between a driven pulley 26 attached to apply tension to the driven pulley 26. . A recording head 30 is mounted on the carriage 23.

On the lower end surface of the drive pulley 24, a drive gear 28 formed integrally with the drive pulley 24 is formed. The drive pulley 24 and the drive gear 28 are rotatably supported by a support shaft 29, and the drive gear 28 meshes with an output gear 32 fixed to an output shaft 31 a of a drive motor 31.

The toothed belt 22, drive pulley 24, driven pulley 26, drive gear 28 and output gear 3
The teeth of the second teeth 22a, 24a, 28a and 32a are all thin, and recording is performed only in one direction in the moving direction of the carriage 23.

Further, the teeth 32a of the output gear 32 are helical with a right-hand twist of 20 degrees, and the teeth 22a of the toothed belt 22 have a pitch of 2 mm (2.03 mm at a right angle to the axis) and a left-hand twist of 10 degrees. It is. As for the helical twist angle of the toothed belt 22, the toothed belt 22 having various twist angles was produced and actually recorded. As a result, the twist angle at which the occurrence of jitter was the least was 10 degrees. When the twist angle is set to 7 degrees or less, a sharp effect cannot be obtained. On the other hand, when the twist angle is 15 degrees, it becomes difficult to manufacture a toothed belt. It is what it was.

It has been confirmed that by setting the twist angle of the toothed belt 22 between 7 degrees and 12 degrees, the meshing vibration which causes the generation of jitter is reduced.

Further, the maximum transmission error e during the running of the toothed belt is expressed by e = 0.5 × tan θ, and when the torsion angle θ = 12 degrees, e = 0.10.
6 mm, which is the amount absorbed in the acceleration region from the reversal of the running direction of the toothed belt 22 to the start of recording. When the value of the torsion angle θ decreases, the maximum transmission error amount e decreases, so that it seems that the play (W′−W) can be increased. Below the degree, the vibration cannot be suppressed, and there is no effect on jitter.

The width (W ') of the driving pulley 14 is 4 mm, and the width (W) of the toothed belt 22 is 3.5 mm.
It is.

Next, the operation of this embodiment having the above-described configuration will be described.

According to the carriage driving mechanism 21 of the serial printer of the present embodiment, by rotating the driving motor 31 in the normal and reverse directions, the toothed belt 22 rotates in the normal and reverse directions, and the carriage 23 reciprocates along the driving shaft 27. It can be moved.

As described above, since the thrust force is generated as the toothed belt 22 travels, the toothed belt 2
2 moves in the thrust direction of the drive pulley 24, thereby causing a transmission error in the carriage 23.

Here, FIGS. 3 to 5 show the results of measurement of the transmission error during forward / reverse rotation depending on the width of the toothed belt 22. Here, for comparison, two types of toothed belts 22 having widths of 2 mm and 3 mm were prepared in addition to the toothed belt 22 having the width dimension of 3.5 mm of the present embodiment. did. The two types of the toothed belts 22 for comparison are also the same as the toothed belt 2 of the present embodiment.
As in the case of No. 2, a hammer having a pitch of 2 mm and a left-hand twist of 10 degrees was used. As described above, the width of the driving pulley 14 and the driven pulley 16 is 4 mm.

FIGS. 3 to 5 show a case where a forward rotation (CW: clockwise rotation) is measured in advance, and a case where a reverse rotation (CCW) is performed. : Counterclockwise rotation), and two plots in the case of a forward rotation operation. Further, the value at the rotation start time during the forward rotation operation after the forward rotation is forcibly set to the transmission error of 0, and the subsequent relative error is measured. further,
The measurement was started at an angle of 90 degrees after the start of rotation.

First, when the width of the toothed belt 22 according to the present embodiment is 3.5 mm, as shown in FIG. It has been confirmed that the transmission error can be solved by reducing the play in the width direction between the driving pulley 24 and the toothed belt 22.

On the other hand, when the width of the toothed belt 22 to be compared is 2 mm, as shown in FIG. 4, the two waveforms do not coincide with each other and the maximum is about 0.4 mm. It can be seen that it is shifted. The shift amount increases to about 0.4 mm between about 720 degrees (two rotations) after the start of rotation, and is substantially constant thereafter. Observing the movement of the toothed belt 22 in the thrust direction at this time, the toothed belt 22 does not move in contact with one end surface of the flange 24a of the driving pulley 24 in the forward rotation operation after the forward rotation, but after the reverse rotation. In the forward rotation operation, the drive pulley 24 is moved to the end face of the reverse side flange 24b.
Is reached at about 720 degrees (two rotations), it is considered that the transmission distance is delayed due to the movement of the toothed belt 22 in the thrust direction.

Further, as shown in FIG.
When the width dimension is 3 mm, the deviation is small and the transmission error is about 0.17 mm, but this is not enough.

As is apparent from the above description, the smaller the difference between the width of the toothed belt 22 and the width of the drive pulley 24 is, the smaller the thrust movement of the toothed belt 22 is, so that the recording position deviation is also small. However, as described above, it was found that if the dimensional difference was 0.5 mm or less, the transmission error was small, and a high-quality printed image was obtained without affecting the recording position accuracy.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes can be made.

[0030]

As described above, in the present invention,
By making the teeth of the toothed belt and the pulley for driving the carriage helical, the meshing vibration between the toothed belt and the drive pulley can be reduced, and the occurrence of jitter during recording can be prevented. By setting the width dimension to 0.5 mm or less of the width of the driving pulley, the amount of movement in the thrust direction at the time of reversing the driving direction due to the slender tooth profile can be reduced. Since the transmission error can be reduced, there is an excellent effect that the recording position accuracy can be accurately obtained and a high quality print image can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a carriage driving mechanism of a serial printer according to the present invention.

FIG. 2 is a partially cutaway front view of the vicinity of a drive gear of the carriage drive mechanism shown in FIG.

FIG. 3 is an explanatory diagram showing a measurement result of a transmission error when using a toothed belt having a width of 3.5 mm in the embodiment of the carriage transfer mechanism of the serial printer according to the present invention.

FIG. 4 is an explanatory diagram showing a measurement result of a transmission error when a toothed belt having a width of 2 mm is used for comparison with the present embodiment.

FIG. 5 is an explanatory diagram showing a measurement result of a transmission error when a toothed belt having a width of 3 mm is used for comparison with the present embodiment.

FIG. 6 is a plan view showing a main part of a carriage driving mechanism of a general serial printer.

7 is a partially cutaway front view in the vicinity of the drive gear of FIG. 6;

FIG. 8 is an explanatory diagram of a thrust force generated when the pulley and the toothed belt of the carriage drive mechanism of FIG.

[Explanation of symbols]

 Reference Signs List 21 carriage drive mechanism of serial printer 22 toothed belt 22a (toothed belt) teeth 23 carriage 24 drive pulley 26 driven pulley 28 reduction gear 31 drive motor

Claims (2)

[Claims] 1. A driving pulley and a driven pulley arranged at a predetermined interval, a toothed belt wound around these driving pulleys and a driven pulley, and a driving motor connected to the driving pulley and driven by a driving motor. And a driving gear for driving the driving pulley with the driving force of the driving motor to reciprocate a carriage to which a part of the toothed belt is connected. And the relationship between the width (W) of the toothed belt and the width (W ') of the driving pulley is W'-W≤0.5 mm. A carriage driving mechanism for a serial printer, wherein 2. The carriage transfer mechanism for a serial printer according to claim 1, wherein the twist angle of the helical of the pulley and the toothed belt is 7 degrees to 12 degrees.