JP3526396B2 - Carriage drive mechanism for serial printer - Google Patents

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 mounts a recording head in a serial printer and drives a carriage that 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 that can be transmitted to

[0002]

2. Description of the Related Art In general, a serial printer in which a carriage having a recording head is moved by driving a toothed belt wound around a driven pulley and a driving pulley is often used as an output device such as a computer and a word processor. Has been.

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

A drive gear 7 which rotates integrally with the drive pulley 4 is connected to the 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 which is 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 axially positioned by an end surface connecting the small diameter portion and the large diameter portion of the support shaft 8 and a retaining ring 9 arranged near the end surface of the small diameter portion of the support shaft 8. Also,
An output gear 11 fixed to an output shaft 10a of a drive motor 10 is meshed with the drive gear 7.

According to the carriage drive mechanism 1 of the serial printer thus configured, the drive motor 1
By rotating 0 forward and reverse, the toothed belt 2 is rotated forward and backward through the output gear 11, the drive gear 7, and the drive pulley 4, and the carriage 3 is reciprocated in the left-right direction shown by the double arrow direction A in FIG. It is designed to be moved.

[0006]

By the way, in the serial printer, the carriage 3 on which the recording head is mounted is mounted.
Vibration may cause unevenness in density in a direction (vertical direction) perpendicular to the moving direction of the carriage 3, which is called jitter. Therefore, resolution of this unevenness in density 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 drive pulley 4, it is found that it is effective to make the tooth profile of the toothed belt 2 and the drive pulley 4 have a toothed shape. In some serial printers, such a helical toothed belt 2 is used.

However, when the toothed belt 2 and the drive pulley 4 have a helical tooth profile, a thrust force is generated by the driving of the toothed belt 2, so that when the traveling direction of the toothed belt 2 is reversed, the toothed belt 2 is toothed. A phenomenon occurs in which the belt 2 moves in the width direction of the drive pulley 4. For example, when the drive pulley 4 is rotated so that the toothed belt 2 moves in the direction of arrow B,
The thrust force that moves the toothed belt 2 in the direction of arrow b acts, while the drive pulley 4 is rotated so that the toothed belt 2 moves in the direction of arrow C, the thrust that moves the toothed belt 2 in the direction of arrow c. The force will work (see Figure 8).

As described above, every time the traveling direction of the toothed belt 2 that is equal to the moving direction of the carriage 3 is reversed, the toothed belt 2 moves in the width direction of the drive pulley 4, resulting in a transmission error. If the error is large, the printing position of the serial printer is displaced, and a high quality recorded image cannot be obtained. The amount of movement in the thrust direction is determined by the width dimension (W ′) of the drive pulley 4 and the toothed belt 2
The larger the difference (play) from the width dimension (W) of the above, the larger it becomes, and the transmission error has a correlation with this difference.

The present invention has been made in view of these points, and the driving force of the driving motor can be smoothly transmitted to the carriage, and the movement of the toothed belt in the width direction of the driving pulley is reduced. Accordingly, it is an object of the present invention to provide a carriage drive mechanism of a serial printer which can reduce a transmission error and can obtain a high-quality recorded image with no print position deviation.

[0010]

In order to achieve the above-mentioned object, a carriage drive mechanism of a serial printer according to the present invention as set forth in claim 1 is characterized by a toothed belt connected to a carriage . Drive pulley , driven pulley,
Each tooth profile of the drive gear and the output gear has a helical shape, and the drive gear and the drive pulley are integrally formed as a two-stage gear.
And the driving direction of the teeth of the drive gear
Formed in the direction opposite to the inclination direction of the pulley teeth
And, lies in the construction of a relation between said width dimension of the toothed belt (W) to the width of the drive pulley (W ') such that W'-W ≦ 0.5mm. By adopting such a configuration, it is possible to reduce the meshing vibration between the toothed belt and the drive pulley and to reduce the widthwise movement amount of the toothed belt during traveling.

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 7 degrees to 12 degrees. By adopting such a configuration, the maximum transmission error amount e during traveling of the toothed belt is further set to e = 0.
The value can be made as small as 5 × tan θ = 0.106 mm, but this value is the amount absorbed in the acceleration region from when the running direction of the toothed belt is reversed to the start of recording.

[0012]

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

As shown in FIGS. 1 and 2, the carriage drive mechanism 21 of the serial printer of this embodiment has a toothed belt 22 called a timing belt.
The toothed belt 22 is formed by a driving pulley 24 and a tension spring 25, which are fixedly provided at a position outside the moving range of the carriage 23 with a predetermined gap.
A carriage 23 slidably attached to a drive shaft 27 is fixed to a part of the toothed belt 22. . A recording head 30 is mounted on the carriage 23.

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

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

Further, the teeth 32a of the output gear 32 are helical with a right twist of 20 degrees, and the teeth 22a of the toothed belt 22 have a pitch of 2 mm (2.03 mm at the right angle to the shaft) and a helical with a left twist of 10 degrees. Is. Regarding the helical twist angle of the toothed belt 22, when the toothed belt 22 having various twist angles was produced and actually recorded, the helix angle at which the least jitter occurred was 10 degrees. Also, if this twist angle is set to 7 degrees or less, it is not possible to obtain a flexible effect, and on the other hand, if the twist angle is 15 degrees, it is difficult to produce a toothed belt, so that a twist angle of 10 degrees is required. It is what

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

Further, the maximum transmission error amount e during running of the toothed belt is represented by e = 0.5 × tan θ, and when the twist angle θ = 12 degrees, e = 0.10.
The value is 6 mm, and this value is the amount absorbed in the acceleration region from when the running direction of the toothed belt 22 is reversed to when recording is started. When the value of the twist angle θ becomes smaller, the maximum transmission error amount e becomes smaller, and it seems that it is possible to increase the backlash (W′−W). However, as described above, the twist angle θ becomes 7 Below the frequency, vibration cannot be suppressed and there is no effect on jitter.

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

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

According to the carriage drive mechanism 21 of the serial printer of the present embodiment, the toothed belt 22 rotates forward and backward by rotating the drive motor 31 forward and backward, and the carriage 23 reciprocates along the drive shaft 27. It can be moved.

Further, 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, which causes a transmission error in the carriage 23.

3 to 5 show the results of measurement of transmission error in forward and reverse rotations due to the width dimension of the toothed belt 22. Here, for comparison, in addition to the toothed belt 22 having the width dimension of the toothed belt 22 of 3.5 mm in the present embodiment, two types of toothed belts 22 having the width dimensions of 2 mm and 3 mm are prepared. did. The two types of toothed belts 22 for comparison are also used in the toothed belt 2 of the present embodiment.
As in the case of 2, a helical with a pitch of 2 mm and a left twist of 10 degrees was used. Further, as described above, the width dimension of the drive pulley 14 and the driven pulley 16 is 4 mm.

3 to 5, in order to investigate the transmission error at the time of reversal, in the case of measuring the forward motion after the forward rotation (CW: clockwise rotation) in advance, and the reverse rotation (CCW). 2 is a plot of two cases when the forward rotation operation is performed after the counterclockwise rotation). Further, the value at the start of rotation during the normal rotation operation after the normal rotation is forcibly set to the transmission error of 0, and the relative error after that is measured. further,
The measurement start point was measured at an angle of 90 degrees after the start of rotation.

First, when the width dimension of the toothed belt 22 according to the present embodiment is 3.5 mm, the waveforms are almost the same as shown in FIG. 3 and there is almost no deviation amount. It was confirmed that the transmission error can be solved by reducing the play in the width direction between the drive pulley 24 and the toothed belt 22.

On the other hand, looking at the result of the width dimension of the toothed belt 22 as a comparison object being 2 mm, as shown in FIG. 4, the two waveforms do not match and the maximum is about 0.4 mm. You can see that they are off. The amount of deviation increases to about 0.4 mm between about 720 degrees (two rotations) after the start of rotation, and is almost constant thereafter. Observing the movement of the toothed belt 22 in the thrust direction at this time, the toothed belt 22 remains in contact with one end surface of the flange 24a of the drive pulley 24 and does not move after the forward rotation after the forward rotation. In the forward rotation operation, the drive pulley 24 is moved up to the end surface of the reverse side flange 24b.
Therefore, 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. 5, the toothed belt 22
When the width dimension of 3 is 3 mm, the deviation is small and the transmission error is about 0.17 mm, but this is not enough.

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

The present invention is not limited to the above-described embodiment, but various modifications can be made.

[0030]

As described above, in the present invention,
Toothed belt for driving the carriage , drive pulley,
By making the teeth of the driven pulley, drive gear, and output gear helical, the meshing vibration between the toothed belt and the drive pulley can be reduced to prevent the occurrence of jitter during recording, and the width dimension of the toothed belt. The width of the drive pulley is 0.5 mm or less with respect to the width of the drive pulley, so the amount of movement in the thrust direction at the time of reversing the drive direction due to the tooth profile can be reduced and the transmission can be reduced. Since the error can be reduced, the recording position accuracy can be accurately obtained, and a high quality printed image can be obtained, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a carriage drive 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 view showing a measurement result of a transmission error when a toothed belt having a width of 3.5 mm is used in the embodiment of the carriage transfer mechanism of the serial printer according to the present invention.

FIG. 4 is an explanatory view showing a measurement result of a transmission error when a toothed belt having a width dimension 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 dimension 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.

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

FIG. 8 is an explanatory diagram of a thrust force generated when the pulley and the toothed belt of the carriage driving mechanism of FIG. 6 are spread.

[Explanation of symbols]

21 Carriage drive mechanism of serial printer 22 Toothed belt 22a Teeth (of toothed belt) 23 carriage 24 drive pulley 26 Driven pulley 28 Reduction gear 31 Drive motor

Claims (2)

(57) [Claims] 1. A drive pulley and a driven pulley arranged at a predetermined interval, a toothed belt wound around the drive pulley and the driven pulley, and an output gear of a drive motor connected to the drive pulley. And a drive gear driven by the output gear.
A carriage driving mechanism of a printer for reciprocating a carriage to which a part of the toothed belt is connected by driving the driving pulley via the drive gear and the toothed belt , the driving pulley , and the driven wheel . Pulley, drive gear
With the helical each tooth of the auxiliary output gear, the drive
The moving gear and the drive pulley are integrally formed as a two-stage gear, and
The direction of inclination of the teeth of the drive gear and the teeth of the drive pulley
Is formed in a direction opposite to the inclination direction of the line, and the relationship between the width dimension (W) of the toothed belt and the width dimension (W ′) of the drive pulley is W′−W ≦ 0.5 mm. A carriage drive mechanism for a serial printer having the above structure. 2. The carriage drive mechanism for a serial printer according to claim 1, wherein the helical twist angle of the pulley and the toothed belt is 7 degrees to 12 degrees.