JP2004202939A - Recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording device, in which the rotation-vibration of a carriage is suppressed, the nonuniformity of scanning speeds at bidirectional recording is reduced, the transmission rigidity is strengthened and low cost and low output motors can be used. <P>SOLUTION: This recording device has a carriage 1, on which a recording head is installed and which reciprocates in a main scanning direction, two motors 5a and 5b for reciprocatingly moving the carriage 1 in the main scanning direction and two timing belts 3a and 3b spanned over pulleys so as to transmit a driving action from the respective motors 5a and 5b to the carriage. The two motors 5a and 5b are arranged at both the ends in the scanning direction of the carriage. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a recording apparatus having a recording unit and a reciprocating scanning unit.
[0002]
[Prior art]
With the remarkable development of electronics technology, the processing power of computers has made remarkable progress. In particular, in order to perform color image processing, a large amount of data must be processed in a short time. Conventionally, there has been a difficulty in terms of processing speed, but in recent years, the improvement in computer performance has made such color image processing very common.
[0003]
In addition, the use range of a recording device for outputting a color image is rapidly expanding. In place of conventional photographic printing, the number of scenes in which a color image is output using a recording device typified by an ink jet printer is increasing. The range of use of ink jet printers is expanding from small business card sizes to large B0 or larger poster sizes. 2. Description of the Related Art As recording apparatuses have become widespread, demands for increasing the stamp size, improving image quality, and improving throughput have been increasing. For this reason, recording apparatuses are moving toward larger sizes and higher image quality.
[0004]
FIG. 3 shows a carriage driving mechanism of a printing apparatus as seen in the prior art. A carriage 1 on which recording means such as a recording head is mounted reciprocates while being guided by a guide shaft 2. The timing belt 3 is fixed to the carriage 1 via a belt holder 4. The timing belt 3 is suspended around the pulley 6 and the idle pulley 7 without slack. The motor 5 as a driving source is connected to the pulley 6. The rotational movement of the motor 5 is converted into a translation movement of the carriage 1 via the pulley 6, the idle pulley 7, and the timing belt 3.
[0005]
[Patent Document 1]
JP 2001-270180 A
[Problems to be solved by the invention]
It is apparent that such a carriage driving mechanism of the recording apparatus according to the related art induces rotational vibration of the carriage 1. FIG. 4 is a drawing of a conventional carriage driving mechanism when viewed from above. Usually, the timing belt 3 is fixed to the end face of the carriage 1. Since the point where the force is transmitted from the motor 5 is separated from the center of gravity G of the carriage 1, yaw vibration is induced in the carriage 1 in the direction of the arrow in FIG. The carriage 1 is guided by the two guide shafts 2. However, since there is a slight mechanical play between the carriage 1 and the guide shaft 2, yawing vibration is inevitable.
[0007]
Further, there is a problem that the rigidity of the timing belt 3 limits the transmission of the driving force from the motor 5 to the carriage 1 and further causes the carriage 1 to vibrate. FIG. 5 is a drawing modeling the dynamic characteristics of the carriage drive mechanism. The motor 5 and the pulley 6 can be regarded as integral rotary rigid elements, and the carriage 1 can be regarded as a translational rigid element. If attention is paid to the dynamic characteristics, the timing belt 3 is modeled as a rigid element. The figure shows a typical spring-mass system.
[0008]
If the rigidity of the timing belt 3 is infinite, the movement of the motor 5 and the pulley 6 and the movement of the carriage 1 are completely synchronized. Conversely, if the rigidity is not sufficiently secured, the motor 1 and the pulley 6 only move unilaterally, and the carriage 1 is not driven. Therefore, the responsiveness of the carriage 1 is limited by the rigidity of the timing belt 3. The transmission rigidity from the motor 5 to the carriage 1 is determined by the rigidity of the timing belt 3. In order to increase responsiveness, the higher the transmission stiffness, the better. In addition, the carriage 1 has a natural vibration caused by the rigidity of the timing belt 3. It is also evident that the natural frequencies induce excellent vibrations. Since the displacement of the vibration increases as the natural frequency becomes lower, the rigidity of the timing belt 3 is preferably higher.
[0009]
In order to improve the throughput, the size of the carriage 1 and the speed of the driving mechanism have been increased, but these are premised on increasing the output of the motor 5 for driving the carriage 1. Increasing the output of the motor 5 leads to an increase in cost and a deterioration in space factor. The cost of the motor 5 tends to increase exponentially with the output. Therefore, it is expected that a low-power and low-output motor can be used.
[0010]
It is also apparent that the carriage drive mechanism of the related art has asymmetric drive transmission during reciprocating movement. This can be explained by the difference between whether the timing belt 3 forms a closed loop and the pulley 6 pulls the carriage 1 directly or via the idle pulley 7.
[0011]
The power transmission of the timing belt 3 is performed by a change in tension. FIG. 6 shows the tension of the timing belt 3 acting on each part of the carriage drive mechanism. Symbol Ta is the tension acting on the pulley 6 and the carriage 1, Tb is the tension acting on the idle pulley 7 and the carriage 1, and Tc is the tension acting on the pulley 6 and the idle pulley 7. When in equilibrium, the respective tensions are in equilibrium. That is, Ta = Tb = Tc. When the motor 5 serving as a driving source is excited and the pulley 6 rotates, such a balanced state is broken and a driving force is transmitted to the carriage 1. The magnitude of the driving force is equal to the difference between Ta and Tb.
[0012]
When the pulley 6 pulls the carriage 1 directly and the carriage 1 approaches the pulley 6, the carriage 1 is pulled by increasing Ta. However, when the carriage 1 is driven in a direction away from the pulley 6, the behavior of the tension becomes complicated. First, the pulley 6 rotates in the counterclockwise direction, the timing belt 3 between the carriage 1 and the pulley 6 becomes slack, and Ta decreases. Then, the balance between Ta and Tb is broken, and the carriage 1 is driven in a direction away from the pulley 6. On the other hand, with the rotation of the pulley 6, the tension increases in the order of Tc and Tb, and the carriage 1 is pulled in the direction of the axle pulley 7, but this operation is accompanied by a delay. That is, when the carriage 1 is driven in a direction away from the pulley 6, first, the timing belt 3 is slackened between the pulley 6 and the carriage 1 to transmit the driving force, and the idle pulley 7 is further delayed. It is towed by.
[0013]
As described above, there is a problem that the drive transmission becomes asymmetric during the reciprocation, and a difference in the scanning speed of the carriage appears as printing unevenness when performing bidirectional printing.
[0014]
JP 2001-270180 A discloses a carriage drive mechanism combining a stepping motor and a DC motor. According to the publication, normally, only the stepping motor is driven, and the DC motor is operated only during acceleration of the carriage. According to this method, although the torque required for acceleration is shared by the DC motor to compensate for the torque shortage of the stepping motor, the operation of the stepping motor and the DC motor are completely different, and the drive transmission during reciprocation is reduced. It is still asymmetric.
[0015]
Therefore, the present invention has been made in view of the above circumstances. That is, an object of the present invention is to suppress the rotational vibration of the carriage, reduce the unevenness in the scanning speed during bidirectional printing, and reduce the transmission stiffness in order to achieve an increase in printing width, improvement in image quality, and improvement in throughput in the printing apparatus. It is an object of the present invention to provide a recording apparatus having a carriage driving mechanism which enables use of an inexpensive and low-power motor.
[0016]
[Means for Solving the Problems]
A typical configuration of the present invention for achieving the above object includes a scanning unit mounted with a recording unit and reciprocating in a main scanning direction, two driving units for reciprocating the scanning unit in a main scanning direction, And two drive transmitting means for transmitting the drive from each of the driving means to the scanning means, wherein the two driving means are arranged at both ends of the scanning means in the scanning direction. .
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are to be appropriately changed depending on the configuration and various conditions of the apparatus to which the present invention is applied, and It is not intended to limit the scope of the invention to them only, unless specifically stated.
[0018]
[First Embodiment]
Hereinafter, a recording apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 are drawings showing a preferred embodiment of the present invention.
[0019]
In FIG. 1, a carriage 1 as a scanning unit on which a recording head as a recording unit is mounted is guided by a guide shaft 2 and reciprocates in a main scanning direction (the direction of the arrow in FIG. 1). In the present embodiment, a recording head of a so-called ink jet recording system that discharges ink according to a signal and performs recording is used. The recording head as the recording means achieves the formation of high-definition characters and images by ejecting liquid droplets from ejection elements using thermal energy, among the ink jet recording methods.
[0020]
Two timing belts 3a and 3b as drive transmission means are fixed to the carriage 1 via belt holders 4a and 4b, respectively. Although the belt holder 4b is not shown in the figure, the timing belts 3a and 3b are fixed to the carriage 1 at positions facing each other with the two guide shafts 2 therebetween.
[0021]
The timing belt 3a is suspended on the pulley 6a and the idle pulley 7a without slack. The pulley 6a and the idle pulley 7a are arranged at both ends of the carriage 1 in the driving direction (the direction of the arrow in FIG. 1). Further, the timing belt 3b is suspended around the pulley 6b and the idle pulley 7b without slack. The pulley 6b and the idle pulley 7b are arranged at both ends in the driving direction of the carriage 1 and symmetrically with the arrangement of the pulley 6a and the idle pulley 7a with the carriage 1 interposed therebetween. The pulley 6a is connected to a motor 5a as a driving means. Similarly, a motor 5b as a driving means is connected to the pulley 6b.
[0022]
In the recording apparatus according to the present embodiment, as shown in FIG. 1, the motor 5a and the motor 5b are symmetrically arranged about the carriage 1. Further, the motors 5a and 5b are arranged at both ends in the main scanning direction, which is the moving direction of the carriage 1.
[0023]
Here, the drive transmission during the reciprocating movement of the carriage 1 will be described with reference to FIG. First, there is a case where the carriage 1 moves in a direction approaching the motor 5a. The motor 5a pulls the carriage 1 so as to approach itself. At the same time, the motor 5b pulls the carriage 1 via the idle pulley 7b. Thus, the two sets of motors 5a and 5b pull the carriage 1 at the same time. Next, when the carriage 1 moves in the direction approaching the motor 5b, only the roles of the motors 5a and 5b are interchanged, and the drive transmission is completely symmetric. That is, the motor 5b pulls the carriage 1 so as to approach itself. At the same time, the motor 5a pulls the carriage 1 via the idle pulley 7a.
[0024]
As described above, the drive transmission from the motors 5a and 5b to the carriage 1 is completely symmetric during the reciprocating movement of the carriage 1, and there is no difference in the movement of the carriage 1 during the reciprocating movement. Is performed, recording unevenness due to the driving accuracy of the carriage 1 does not occur.
[0025]
The timing belts 3a and 3b are fixed to the carriage 1 at both ends of the carriage 1 with the guide shaft 2 interposed therebetween. In such a configuration, yawing vibration of the carriage 1 is extremely unlikely to be induced. FIG. 2 is a diagram when the present embodiment is viewed from above. As is apparent from FIG. 2, the timing belts 3a and 3b are fixed at positions facing the carriage 1 with the center of gravity G of the carriage 1 interposed therebetween. Since the transmission of the forces from the motors 5a and 5b sandwiches the center of gravity G, almost no moment is generated in the direction of the arrow in FIG. Therefore, the yawing vibration is eliminated from the carriage 1, and the reduction in the vibration of the carriage realizes a high image quality of the recording apparatus.
[0026]
Further, the transmission rigidity is enhanced by using the two timing belts 3a and 3b. This has the effect of improving the responsiveness of the carriage and suppressing the vibration of the carriage. The transmission rigidity from the motor to the carriage is determined by the rigidity of the timing belt. If the same timing belt is used, in the present embodiment, the transmission rigidity is doubled as compared with the conventional example using only one timing belt.
[0027]
When the carriage 1 is driven by the two sets of motors 5a and 5b, the output required for each motor is reduced by half. The output required for the motor of the present embodiment is halved compared to the conventional example using only one motor. Therefore, an inexpensive and low-output motor can be used, and a high-speed carriage can be easily realized. This greatly contributes to improving the throughput.
[0028]
[Other embodiments]
Note that, in the above-described embodiment, an example in which the rotation axes of the motors 5a and 5b are in a direction perpendicular to the drawing when the device is viewed from above is illustrated, but the embodiment of the present invention is limited to such a case. Not something. The direction of the rotation axis may be either vertical or horizontal. Further, the directions of the rotating shafts of the motor 5a and the motor 5b do not have to match. The essence of the present invention is to configure two sets of motors and two sets of belts so as to provide a bidirectional symmetric drive, and the present invention can be implemented in various forms.
[0029]
In the above-described embodiment, the type and number of print heads were not specifically illustrated and described. However, the present invention is directed to an inkjet printing apparatus using one print head, a plurality of print heads using different color inks. Applicable regardless of the type and number of recording heads, such as an inkjet recording device for color recording using a recording head of different colors, or an inkjet recording device for gradation recording using a plurality of recording heads for recording with the same color and different density inks And the above-mentioned effects can be achieved.
[0030]
Further, as the recording means (recording head), a recording type such as a cartridge type in which a recording head and an ink tank are integrated, or a constitution in which a recording head and an ink tank are separately provided and these are connected by an ink supply tube, and the like. Regardless of the configuration of the ink tank, the same can be applied and the same effect can be achieved.
[0031]
When the present invention is applied to an ink jet recording apparatus, for example, the present invention can be applied to an apparatus using a recording unit using an electromechanical transducer such as a piezo element. This provides an excellent effect in an ink jet recording apparatus using a recording means of the following method. According to such a method, it is possible to achieve higher density and higher definition of recording.
[0032]
Further, even with a serial type recording head that performs recording while scanning in a direction perpendicular to the sheet conveyance direction, a recording head fixed to a carriage or mounted on the carriage to establish an electrical connection with the apparatus main body or an apparatus main body. The present invention is also effective when a replaceable chip-type recording head capable of supplying ink from the printer or a cartridge-type recording head having an ink tank provided integrally with the recording head itself is used.
[0033]
In addition, as the form of the above-mentioned ink jet recording apparatus, in addition to those used as image output terminal devices of information processing equipment such as computers, an ink jet input / output apparatus capable of mounting a scanner or the like other than a recording head on a carriage, a reader And a facsimile apparatus having a transmission / reception function.
[0034]
In the above-described embodiment, the ink jet recording method is exemplified as the recording method. However, the recording method is not limited to the ink jet recording method.In addition, a thermal transfer recording method, a thermal recording method, and an impact recording method such as a wire dot recording method, or Other recording methods such as an electrophotographic method can be applied.
[0035]
Although various embodiments of the present invention have been shown and described, the spirit and scope of the present invention are not limited to the specific description and drawings in this specification. Hereinafter, examples of embodiments of the present invention will be listed.
[0036]
[Embodiment 1]
Scanning means mounted with a recording means and reciprocating in the main scanning direction, two driving means for reciprocating the scanning means in the main scanning direction, and two driving means for transmitting driving from each of the driving means to the scanning means And a transmitting unit, wherein the two driving units are respectively disposed at both ends of the scanning unit in the scanning direction.
[0037]
[Embodiment 2]
2. The recording apparatus according to claim 1, wherein the two drive transmission units are fixed to the scanning unit at positions facing each other across the center of gravity of the scanning unit. 3.
[0038]
[Embodiment 3]
3. The recording apparatus according to claim 1, wherein the recording unit performs recording by ejecting ink in response to a signal.
[0039]
[Embodiment 4]
The recording apparatus according to claim 3, wherein in the recording apparatus, a recording unit supplies a current to the electrothermal transducer in response to a signal, and discharges ink by thermal energy generated by the electrothermal transducer.
[0040]
【The invention's effect】
As described above, according to the present invention, during the reciprocating movement of the scanning means, the drive transmission from the driving means to the scanning means is completely symmetrical, and no difference in the movement of the scanning means occurs during the reciprocating movement. Also, even in bidirectional printing, printing unevenness due to the driving accuracy of the scanning unit does not occur.
[0041]
Further, since the two drive transmission means are fixed at positions opposite to the scanning means with the center of gravity of the scanning means therebetween, the transmission of the force from the two driving means sandwiches the center of gravity. Almost no moment is generated. Therefore, the vibration of the scanning unit in the rotation direction is reduced, and the reduction of the vibration of the scanning unit realizes high quality of the recording apparatus.
[0042]
Further, the transmission rigidity is enhanced by using two drive transmission means. This has the effect of improving the responsiveness of the scanning unit and suppressing vibration of the scanning unit.
[0043]
Since two driving units are used, the output required for each driving unit is reduced by half. Therefore, it is possible to use an inexpensive and low-output driving unit, and the speeding up of the scanning unit can be easily realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a preferred embodiment of the present invention.
FIG. 2 is a diagram when an embodiment according to the present invention is viewed from above.
FIG. 3 is a drawing showing a typical example of the prior art.
FIG. 4 is a view for explaining yawing vibration of a carriage according to the related art.
FIG. 5 is a drawing modeling the dynamic characteristics of the carriage drive mechanism.
FIG. 6 is a diagram illustrating tension of a timing belt.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Carriage 2 ... Guide shaft 3a, 3b ... Timing belt 4a, 4b ... Belt holder 5a, 5b ... Motor 6a, 6b ... Pulley 7a, 7b ... Idle pulley

Claims (1)

Scanning means mounted with recording means and reciprocated in the main scanning direction;
Two driving means for reciprocating the scanning means in the main scanning direction;
Two drive transmitting means for transmitting drive from each of the driving means to the scanning means;
Has,
The recording apparatus according to claim 1, wherein the two driving units are arranged at both ends of the scanning unit in a scanning direction.

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