JP2004082453A - Carriage driver and liquid ejector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carriage driver in which a transition can be made from an accelerating region to a constant speed region through smooth speed change by modifying the mechanical structure slightly without requiring any upgrade of a motor or complication of a motor drive circuit. <P>SOLUTION: The carriage driver comprises a drive pulley 17 fixed to the shaft 19 of a stepping motor 16, a driven pulley 18 being paired with the drive pulley, and a belt 20 entrained about both pulleys to be turned through a rotation of the motor and fixed with a carriage 15 to move integrally. The carriage is arranged to reciprocate through an accelerating region, a constant speed region and a decelerating region and the radius r1 of the drive pulley is set such that the inertial moment M2 of the carriage on the motor shaft becomes not higher than two times of the inertial moment M1 of the rotor of the stepping motor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a carriage driving device configured to reciprocate a carriage in an acceleration region, a constant speed region, and a deceleration region, and a liquid ejecting apparatus using the same.
[0002]
[Prior art]
An ink jet recording apparatus, which is an example of a liquid ejecting apparatus, generally includes a recording sheet conveying unit, a recording execution unit that executes recording on a recording sheet, and a recording sheet discharging unit that discharges a recording sheet. The means includes a carriage on which a recording head is mounted, and a carriage driving device for reciprocating the carriage in a main scanning direction orthogonal to the recording paper transport direction. Then, ink is ejected from a recording head mounted on the carriage, and recording is performed on recording paper.
[0003]
The carriage driving device uses a DC motor or a stepping motor as a power source, and has a driving pulley attached to a motor shaft of the motor, a driven pulley that forms a pair with the driving pulley, and bridges between the driving pulley and the driven pulley. And a belt that is rotated by the rotation of the motor as a power, and a belt is attached so that the carriage moves integrally.The carriage has an acceleration area based on a control signal sent from a control unit. It is configured to reciprocate in a constant speed region and a deceleration region. In most printing apparatuses, the drive pulley and the driven pulley are formed to have the same diameter, and the printing is performed by discharging ink from the print head in a constant speed region in which the movement of the carriage is stable. I have.
[0004]
[Problems to be solved by the invention]
However, in the conventional carriage driving device, the stability of the carriage moving speed in the constant speed traveling region of the carriage is considered, but the transition from the acceleration region to the constant speed region or the transition from the constant speed region to the deceleration region is performed. It has not been practically sufficient to realize the operation by a smooth speed change. That is, there has been no attempt at realizing the transition by a smooth speed change by a slight change in the mechanical structure without upgrading the motor or complicating the motor drive circuit.
[0005]
The purpose of the present invention is to realize the above-mentioned transition from the acceleration region to the constant speed region by a smooth speed change by a slight change of the mechanical structure without upgrading the motor or complicating the motor drive circuit. And a liquid ejecting apparatus using the same.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of a carriage driving device according to the present invention includes a stepping motor, a driving pulley attached to a motor shaft of the stepping motor, a driven pulley paired with the driving pulley, A belt that is wound around the driving pulley and the driven pulley, is rotated by using the rotation of the stepping motor as a power, and is attached so that a carriage moves integrally. A carriage driving device configured to reciprocate in an acceleration region, a constant speed region, and a deceleration region based on an inertia moment of a rotor of the stepping motor, and a carriage on a motor shaft of the stepping motor. When the moment of inertia of M2 is M2, M2 is less than twice M1. It is characterized in that the radius r1 of the drive pulley is set to.
[0007]
In the present invention, the moment of inertia M2 on the motor shaft of the carriage, which is a load of the motor torque, is reduced only by reducing the radius r1 of the drive pulley without changing the structure and weight of the carriage itself. Things. Specifically, the moment of inertia M2 of the carriage is set to be less than twice the moment of inertia M1 of the rotor of the stepping motor. Therefore, the load of the motor torque is reduced by a slight change in the mechanical structure such as reducing the radius r1 of the drive pulley without accompanying the upgrading of the motor and the complication of the motor drive circuit. For example, when the vehicle shifts to the constant speed region, the vehicle can be shifted by a smooth speed change without a large speed change.
In a second aspect of the carriage driving device according to the present invention, in the first aspect, when the radius of the driven pulley is r2, the radius r2 of the driven pulley is set to be larger than the radius r1 of the driving pulley. It is characterized by having been done. According to the present invention, the rotation speed is reduced by an amount corresponding to the large radius r2 of the driven pulley, and the durability and wear resistance of the driven pulley supporting portion can be improved.
[0008]
According to a third aspect of the carriage driving device according to the present invention, in the first aspect or the second aspect, a portion of the motor shaft of the stepping motor to which the drive pulley is attached is formed to have a smaller diameter than other portions. It is characterized by the following. Reducing the diameter of the drive pulley also reduces the diameter of the motor shaft to which the drive pulley is attached, so that the rigidity of the thinned motor shaft is reduced and the motor shaft is more likely to be bent by the tension of the belt. However, according to the present invention, the portion of the motor shaft other than the portion to which the drive pulley is attached can be made thicker so as not to reduce the rigidity, so that the risk of occurrence of the bending is small.
[0009]
According to a fourth aspect of the carriage driving device according to the present invention, in the third aspect, the small diameter portion of the motor shaft is formed by a stepped structure of the motor shaft having a step near a driving pulley. It is a feature. With the motor shaft having the stepped structure, the structure can be simplified and the manufacturing can be simplified, and the risk of the bending occurring due to the belt tension can be reduced.
[0010]
Further, the liquid ejecting apparatus according to the present invention includes an ejected medium transporting unit, an ejection executing unit that ejects the liquid to the ejected medium, and an ejected medium discharging unit that ejects the ejected medium. The means is a liquid ejecting apparatus including a carriage on which the liquid ejecting head is mounted, and a carriage driving device for reciprocating the carriage in a main scanning direction orthogonal to the direction of transport of the medium to be ejected. It is characterized by comprising the carriage driving device according to any of the first to fourth aspects.
[0011]
According to the present invention, there is provided a liquid ejecting apparatus that ejects (discharges) a liquid ink from a recording head that is a liquid ejecting head to perform recording on a recording medium or the like to be ejected, such as an ink jet printer. The carriage driving device according to any one of the first to fourth aspects is used. Therefore, the inertia moment M2 on the motor shaft of the carriage, which is the load of the motor torque, can be reduced by a slight change in the mechanical structure such as reducing the diameter of the drive pulley without upgrading the motor or complicating the motor drive circuit. Therefore, the transition from the acceleration region to the constant speed region in the carriage movement traveling can be realized by a smooth speed change, so that the recording quality can be maintained at a certain level or more without lowering the throughput. .
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an embodiment of an ink jet printer which is an example of a liquid ejecting apparatus according to the present invention, and FIG. 2 is a front view schematically showing an enlarged portion of a carriage driving device. . A main frame 11 is supported and fixed to a lower case 10 as a lower housing. Left and right side frames 12 and 13 are provided on both sides of the main frame 11.
[0013]
A carriage guide shaft 14 is fixed to the side frames 12 and 13. The stepping motor 16 is fixed to the main frame 10. A timing belt 20 is stretched around a driving pulley 17 attached to a motor shaft 19 of the stepping motor 16 and a driven pulley 18 attached to the main frame 11. The carriage 15 is attached to the belt 20, and the belt 20 is rotated via a driving pulley 17 by using a stepping motor 16 as a power source. With the rotation of the belt 20, the carriage 15 is moved by the carriage guide. While being guided by the shaft 14, the recording medium P reciprocates in a main scanning direction orthogonal to the conveying direction of the recording medium P. Then, during the traveling, the ink is ejected onto the recording medium P facing away from the recording head 21 to execute the recording. In FIG. 1, reference numeral 22 denotes a color ink cartridge, and reference numeral 23 denotes a platen that supports a recording medium from below.
FIG. 4 is a sectional view of the stepping motor 16, in which reference numeral 31 denotes a rotor, and reference numerals 32 and 33 denote bearings of the motor shaft 19. As shown in FIG. 4, the motor shaft 19 has a small-diameter portion 29 in which a portion to which the drive pulley 17 is attached is smaller than the other portion. Further, the small diameter portion 29 of the motor shaft 19 is formed by a stepped structure of the motor shaft having a step 40 near the drive pulley 17.
[0014]
The carriage driving device 30 according to the present embodiment includes the stepping motor 16, a driving pulley 17 attached to a motor shaft 19 of the stepping motor 16, a driven pulley 18 attached to the main frame 11, And a belt 20 on which the carriage 15 is attached so that the carriage 15 is integrally moved while being rotated by the rotation of the stepping motor 16 as power. The carriage 15 is configured to reciprocate in an acceleration region, a constant speed region, and a deceleration region based on a control signal.
[0015]
When the moment of inertia of the rotor 31 of the stepping motor 16 is M1, and the moment of inertia of the carriage 15 on the motor shaft 19 of the stepping motor 16 is M2, M2 is twice as large as M1. The radius r1 of the driving pulley 17 is set as follows. Here, the moment of inertia M1 of the rotor 31 of the stepping motor 16 is determined to be a magnitude unique to the motor. The inertia moment M2 of the carriage 15 on the motor shaft 19 of the stepping motor 16 is a state where the mass m exists at the point of the radius r1 of the driving pulley 17 when the mass of the carriage is m. It is determined by the product of “mass m” and “square of radius r1”. Therefore, by reducing the radius r1 of the driving pulley 17, the inertia moment M2 of the carriage 15 on the motor shaft 19 can be reduced without changing the mass m.
[0016]
In the present embodiment, the radius r2 of the driven pulley 18 is set to be larger than the radius r1 of the driving pulley 17, in the present embodiment, when the radius of the driven pulley 18 is r2. Accordingly, the number of rotations is reduced by the radius r2 of the driven pulley 18, and the durability and wear resistance of the driven pulley supporting portion can be improved.
[0017]
Further, the liquid ejecting apparatus according to the present embodiment includes an ink jet recording apparatus as described above, and the ink jet recording apparatus includes a conveying roller (not shown) as a medium to be ejected and a medium to be ejected. The apparatus includes a recording execution unit that executes recording on a certain recording medium P, and a discharge roller (not shown) that is an ejection medium discharge unit that discharges the recording medium P, and the ejection execution unit has a recording head 21 mounted thereon. And a carriage driving device 30 for reciprocating the carriage 15 in a main scanning direction orthogonal to the recording medium conveyance direction, wherein the carriage driving device 30 has an inertia of a rotor 31 of the stepping motor 16. The moment of inertia M2 of the carriage 15 on the motor shaft 19 of the stepping motor 16 is twice or less the moment M1. In which the radius r1 of the drive pulley 17 is set to be.
[0018]
Hereinafter, the above-described embodiment will be described in more detail while describing its operation and effects. According to the present invention, the moment of inertia M2 of the carriage 15 on the motor shaft 19, which is a load of the motor torque of the stepping motor 16, can be determined by changing the radius r1 of the drive pulley 17 without changing the structure and weight of the carriage 15 itself. It is made smaller only by reducing the diameter. Specifically, the moment of inertia M2 of the carriage 15 is set to be equal to or less than twice the moment of inertia M1 of the rotor 31 of the stepping motor 16. Therefore, the load of the motor torque is reduced by a slight change in the mechanical structure such as reducing the radius r1 of the drive pulley 17 without upgrading the motor or complicating the motor drive circuit. When shifting from the acceleration region to the constant speed region, the shift can be made by a smooth speed change without a large speed change.
[0019]
FIG. 3 shows the speed change when the carriage 15 shifts from the acceleration region to the constant speed region for both the present invention and the comparative example. As is apparent from this figure, in the conventional carriage driving device, the acceleration is not uniform because the moment of inertia of the carriage 15 on the motor shaft 19 is large, and therefore, a large speed is required even when shifting from the acceleration state to the constant speed state. With change. On the other hand, in the present invention, the inertia moment M2 of the carriage 15 on the motor shaft 19 is reduced by the square of the radius r1 due to the reduction in the diameter of the driving pulley 17, so that the acceleration becomes uniform as shown in the figure, and therefore the acceleration is uniform. When shifting from the state to the constant speed state, the transition is smooth without a large speed change.
[0020]
Here, the reason why M2 is twice or less than M1 is that the effect of reducing the inertia moment M2 of the carriage 15 can be obtained reliably and stably. In that sense, the above-mentioned “less than twice” which is the limit value does not need to be exactly a double just as a boundary value, and is substantially “about twice or less”. M2 is calculated by the product of "total mass" as the load of the carriage 15 and "square of the radius of the driving pulley". The total mass also takes into account the mass of the belt 20, the frictional resistance, and the like. Then it will be more accurate.
[0021]
In reducing the moment of inertia M2 of the carriage 15, the structure and weight of the carriage 15 itself need not be changed as described above. In addition to reducing the radius r1 of the drive pulley 17, If the structure and weight of the carriage 15 itself are reduced, the smooth speed change can be realized more stably.
[0022]
If the radius r1 of the driving pulley 17 is reduced, the rotation speed of the belt 20, that is, the moving speed of the carriage 15 is reduced as it is, but the decrease in the carriage moving speed due to the reduction in the diameter of the driving pulley 17 is as follows. This can be easily prevented by changing the stepping motor 16 to one having a smaller number of steps per rotation, for example, by replacing a 200 step / rev stepping motor with a 96 step / rev stepping motor.
[0023]
Reducing the diameter of the drive pulley 17 also leads to a reduction in the diameter of the motor shaft 19 to which the drive pulley 17 is attached. Therefore, the rigidity of the thinned motor shaft decreases, and the motor shaft may be bent by the tension of the belt 20. Increase. However, according to the present embodiment, the portion other than the small-diameter portion 29 of the motor shaft 19 to which the drive pulley 17 is attached can be made thick so as not to reduce the rigidity, so that the risk of the occurrence of the bending is small. In addition, since the small diameter portion 29 of the motor shaft 19 is formed by a stepped structure of the motor shaft having a step 40 near the drive pulley 17, the structure is simple and the manufacturing is simple, and there is a possibility that the bending may occur due to belt tension. Can be reduced.
[0024]
FIG. 5 is a diagram illustrating measurement data of the comparative example and the first to third examples. As is apparent from this figure, the radius r1 of the driving pulley 17 is changed from 13.475 / 2 mm (Comparative Example) to 6.738 / 2 mm (Example 1), or 6.468 / 2 mm (Example 2 and Example 2). By simply reducing the diameter to 3), the moment of inertia M2 of the carriage (CR) on the motor shaft 19 is increased from 113.49 in the comparative example to 28.37 in the first embodiment and 26.15 in the second and third embodiments. Become smaller.
[0025]
Where the moment of inertia M1 of the rotor is 20, the value of the comparative example is about 5 to 6 times the value of the moment of inertia M1, but Examples 1 to 3 have substantially the same value as the moment of inertia M1. That is, the moment of inertia M2 of the carriage 15 on the motor shaft 19 of the stepping motor 16 is less than or equal to twice the moment of inertia of the rotor 31 of the stepping motor 16 with respect to M1. Thereby, the speed stability as shown in FIG. 3 is obtained.
[0026]
By changing the number of steps (step / rev) of the stepping motor 16 from 200 in the comparative example to 100 in the first embodiment and 96 in the second and third embodiments, the traveling speed of the carriage 15 is increased. Is not reduced.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an ink jet printer according to the present invention.
FIG. 2 is an enlarged front view schematically showing a carriage driving device according to the present invention.
FIG. 3 is a diagram showing a speed change when the carriage shifts from an acceleration region to a constant speed region.
FIG. 4 is a sectional view of a stepping motor.
FIG. 5 is a diagram showing measurement data of a comparative example and Examples 1 to 3.
[Explanation of symbols]
Reference Signs List 11 main frame, 14 carriage guide shaft 15 carriage, 16 stepping motor 17 drive pulley, 18 driven pulley 19 motor shaft, 20 belt 21 recording head, 30 carriage drive M1 motor rotor inertia, M2 carriage inertia r1 drive pulley Radius, r2 radius of driven pulley

Claims (5)

A stepper motor,
A drive pulley attached to a motor shaft of the stepping motor;
A driven pulley paired with the drive pulley,
A belt that is hung over the drive pulley and the driven pulley, is rotated with the rotation of the stepping motor as power, and is attached so that the carriage moves integrally.
A carriage driving device configured to reciprocate in an acceleration region, a constant speed region, and a deceleration region based on a control signal,
When the moment of inertia of the rotor of the stepping motor is M1 and the moment of inertia of the carriage on the motor shaft of the stepping motor is M2, the radius r1 of the driving pulley is set so that M2 is not more than twice M1. A carriage driving device. 2. The carriage driving device according to claim 1, wherein when a radius of the driven pulley is r2, a radius r2 of the driven pulley is set to be larger than a radius r1 of the driving pulley. 3. The carriage driving device according to claim 1, wherein a portion of the motor shaft of the stepping motor to which the driving pulley is attached has a smaller diameter than the other portion. 4. The carriage driving device according to claim 3, wherein the small diameter portion of the motor shaft is formed by a stepped structure of the motor shaft having a step near a driving pulley. A medium to be ejected, a means for performing liquid ejection on the medium to be ejected, and a means for ejecting medium to be ejected for ejecting the medium to be ejected, wherein the means for ejecting comprises a carriage equipped with a liquid ejecting head; 5. A liquid ejecting apparatus comprising: a carriage driving device that reciprocates the carriage in a main scanning direction orthogonal to a direction in which the medium to be ejected is conveyed. 5. The liquid ejecting apparatus according to claim 1, wherein the carriage driving device is A liquid ejecting apparatus comprising the carriage driving device described above.

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