JP2007144675A - Carriage vibration-proofing apparatus for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carriage vibration-proofing apparatus equipped on an image forming apparatus for suppressing vibration accompanied with high speed movement of a carriage carrying a recording head for delivering ink and recording an image and for performing a recording with a high printing quality. <P>SOLUTION: As a pulley holder vibration attenuating part for attenuating vibration of a pulley holder 12 rotatably holding a following pulley 10, a frictional member for enlarging a frictional resistance is provided on a contacting face on at least one side of a contacting region E between this housing and the pulley holder 12 in a chassis 16. Propagation of a vibration phenomenon caused by an excessive frequency generated by providing a balance weight to a carriage is suppressed thereby by attenuating and diminishing the vibration of the pulley holder 12. An image with a high printing quality can be obtained thereby by preventing vibration of the carriage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is provided in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multi-function machine, and has a recording head for recording an image on a sheet of recording material and moves in a scanning direction. About.

  An ink jet recording type image forming apparatus that records ink on a sheet by ejecting ink from a recording head is applied to the above various devices because of low noise, low running cost, and easy miniaturization and colorization of the apparatus. ing. In addition to the recording head, the carriage that carries the recording head and reciprocates in the scanning direction has many components and devices such as an ink tank, an ink supply tube, a carriage position sensor, and a control circuit board.

  In recent years, the main body of an image forming apparatus tends to be miniaturized. However, the carriage alone is difficult to miniaturize because of the structure carrying the above-mentioned many parts and devices, and an ink tank or the like is added. On the contrary, there are even cases where the size is increased. Further, as the operation of the image forming apparatus increases, the moving speed of the carriage that reciprocates during the recording operation also increases. When the speed of the carriage is increased, reaction force and inertial force due to the movement increase, which causes vibration in the image forming apparatus main body. There is an inconvenience that the vibration generated in the main body of the image forming apparatus is transmitted to the floor of the installation place. In addition to such inconvenience, if the vibration propagates to the recording head itself or the sheet being recorded, the ink droplets will not land on the desired position on the sheet, causing deterioration in printing quality such as ruled line deviation and printing color unevenness. .

  Regarding the vibration problem associated with such high speed, the applicant is equipped with a mechanism to suppress noise and image quality deterioration by mitigating vibration generated by reaction force and inertial force during carriage movement. An image forming apparatus has been proposed (see, for example, Patent Document 1). In this method, the balance weight is moved in the direction opposite to the direction in which the carriage moves, so that the movement reaction force and inertial force of the carriage are offset and attenuated to suppress vibration.

  By the way, since the balance weight is mounted, there is a new problem that an excessive vibration phenomenon occurs in the carriage. 5 and 6 are structural examples schematically showing the form of vibration generation when a balance weight is mounted. An endless belt 6 is wound between a driving pulley 9 and a driven pulley 10, and the belt 6, the carriage 1 and the balance weight 17 are connected to a position where they do not interfere with each other. The driven pulley 10 is rotatably supported by the pulley holder 12. The pulley holder 12 is pressed and urged by a tension spring 13 in a direction to increase the tension of the belt 6. In the case of FIG. 5, when the carriage 1 vibrates in the direction of arrow F, the drive pulley 9 that rotates by rotational power from a drive source motor (not shown) vibrates in the direction of arrow G opposite to the direction of vibration. In the case of FIG. 6, when the carriage 1 vibrates in the direction of arrow H, the drive pulley 9 rotates in the direction of arrow I, and the balance weight 17 vibrates in the direction of arrow J in the opposite direction. At the same time, the pulley holder 12 vibrates in the direction of arrow K in the same direction as the vibration direction of the balance weight.

  FIG. 7 is a graph showing the frequency characteristics of vibrations generated when the carriage 1 moves in the main scanning direction with respect to disturbance in the case where the balance weight 17 is mounted and in the case where there is no weight not mounted. is there. In the graph, a solid line indicates a case where there is a weight, a dotted line indicates a case where there is no weight, the horizontal axis indicates frequency, the vertical axis in the upper part of the graph indicates gain, and the vertical axis in the lower part of the graph indicates phase.

  When there is no weight, the vibration of the carriage 1 has the maximum frequency f1, but even when there is a weight, excessive vibration with the frequency f2 is generated. The cause of the vibration with the excessive frequencies f1 and f2 regardless of whether the weight is present or not is caused by the vibration of the carriage 1 in the F direction and the vibration of the drive pulley 9 in the G direction as shown in FIG. This is the natural vibration that results. In addition, the excessive vibration phenomenon of the frequency f2 that occurs when there is a weight is a natural vibration caused by the vibration of each member as shown in FIG. That is, the vibration of the carriage 1 in the H direction, the vibration of the pulley holder 9 in the I direction, the vibration of the balance weight 17 in the J direction, the vibration of the pulley holder 12 in the K direction, and a drive source motor (not shown). ) Rotation vibration.

JP 2004-34647 A

  From the above, the vibration phenomenon due to the excessive frequency f2 occurs in each member such as the carriage 1, the drive pulley 9 and the pulley holder 12 by the balance weight 17 because the pulley holder 12 moves to apply tension to the belt 6. It can be noted that there is. Therefore, in order to prevent the mounting of the balance weight 17 from being adversely affected, effective vibration isolation is performed so that the vibration phenomenon of the excessive frequency f2 is generated in the carriage 1 during the recording operation and the print quality recorded on the sheet is not deteriorated. It is necessary to adopt a structure.

  As described above, an object of the present invention is provided in an image forming apparatus for performing high-print quality recording by suppressing vibration associated with high-speed movement of a carriage equipped with a recording head for recording an image by discharging ink. Another object of the present invention is to provide a carriage vibration isolator.

  In order to achieve the above object, a carriage vibration isolator for an image forming apparatus according to the present invention carries a recording head that ejects ink and records an image on a sheet of recording material, and reciprocates in the scanning direction. A belt that pulls and moves the carriage, a balance weight that is attached to the belt and moves in a reverse direction that reduces reaction force due to movement of the carriage, and a pair of drive pulleys that stretch the belt. A driven pulley, a pulley holder that is movable in a belt stretching direction while the driven pulley is rotatably held, a chassis that movably supports the pulley holder, and a tension that is attached to the chassis and applies tension to the belt. Pulley holder vibration damping that has an elastic member that presses and urges the pulley holder in a direction to dampen the vibration of the pulley holder There is characterized in that provided in the chassis.

  According to the carriage vibration isolator of the image forming apparatus of the present invention, the vibration phenomenon due to the excessive frequency generated by providing the balance weight is propagated to the carriage. Vibration is reduced and suppressed by the pulley holder vibration attenuator. By thus preventing vibration of the carriage, a high-quality image can be obtained.

  Hereinafter, a preferred embodiment of a carriage vibration isolator for an image forming apparatus according to the present invention will be described in detail with reference to the drawings for an inkjet recording apparatus.

(Carriage vibration isolator)
-First embodiment-
As shown in FIG. 1, the carriage 1 is mounted with a head cartridge equipped with a recording head, is guided by the guide shafts 4 and 5 and slides, and can reciprocate in the scanning direction. The ink supply unit 3 supplies the stored ink to the recording head. Further, the entire carriage mechanism is connected to the control unit on the image forming apparatus main body side via the flexible substrate 2 to receive an operation instruction signal, and on the contrary to transmit an ink ejection signal to the main body side control unit. Then, recording is performed by printing on the sheet while transmitting / receiving to / from the main body side control unit.

  The carriage 1 is fastened to an endless carriage pulling belt 6 wound between a driving pulley 9 and a driven pulley 10 and moves integrally with the traveling movement of the belt 6. The drive pulley 9 rotates by receiving rotational power from the drive source motor 11 in a state where the gear is decelerated appropriately. The driven pulley 10 is rotatably supported by the pulley holder 12. The pulley holder 12 is movable in the belt traveling direction, that is, the carriage scanning direction, and a constant tension is applied to the carriage pulling belt 6 by pushing the pulley holder 12 together with the driven pulley 10 by a tension spring (elastic member) 13. The conveyance roller 14 is rotated by a motor (not shown) to convey the sheet. A paper discharge roller 15 discharges the recorded sheet. The above members and mechanisms are built into the chassis 16.

  FIG. 2 shows a belt tension mechanism constituted by the driven pulley 10, a pulley holder 12 that pivotally supports the driven pulley 10, and a tension spring 13. That is, the tension spring 13 presses the pulley holder 12 to apply a certain tension to the belt 6. The pulley holder 12 is guided by the guide 18 so as to be movable only in the carriage scanning direction within the chassis 16.

  Therefore, in the belt tension mechanism, a pulley holder vibration damping part, which is a main part of the carriage vibration isolator of the present embodiment, is provided as follows.

  That is, the hatched portion indicated by the symbol E in FIG. 2 indicates the area of the surface where the pulley holder 12 contacts the chassis 16. Assuming that the pulley holder 12 can move with respect to the chassis 16 in the contact area E, a friction member (or friction means) is provided on one or both contact surfaces of the pulley holder 12 and the chassis 16 in the contact area E. Is provided. Although this friction member is not particularly illustrated, it is not limited to a special one as long as it has a property by a material and a shape capable of increasing the friction force between the pulley holder 12 and the chassis 16. For example, in the contact region E between the pulley holder 12 and the chassis 16, the intended purpose can be achieved by subjecting at least one of the contact surfaces of both members to surface processing with rough unevenness that increases the frictional resistance. Further, a sheet material having a high frictional resistance may be provided by being attached to at least one of the contact surfaces of both members.

  Therefore, by providing a pulley holder vibration damping portion in such a belt tension mechanism, an appropriate tension is applied to the belt 6 and the balance weight 17 is attached, so that the carriage of the present embodiment including the balance weight 17 is provided. An anti-vibration device is configured.

  The balance weight 17 is connected to the belt 6 at a position where it does not interfere with the carriage movement with a structure capable of canceling and attenuating the reaction due to the reaction or inertia of the carriage 1 reciprocated in the scanning direction by being locked to the belt 6. In FIG. 2, when the carriage 1 scans and moves in the direction of arrow A, the balance weight 17 moves in the direction of arrow B in the direction opposite to the direction of carriage movement in the direction A. The movement reaction force and inertial force generated by the movement of the carriage 1 in the A direction are counteracted by the movement of the balance weight 17 in the reverse direction, thereby attenuating and reducing the vibration generated in the entire apparatus.

  During such an action, in the present embodiment, excessive vibration due to the frequency f2 generated by attaching the balance weight 17 is handled as follows. When the carriage 1, the drive pulley 9, the pulley holder 12, and the balance weight 17 vibrate, the pulley holder 12 and the chassis 16 come into contact with each other via a friction member in the contact region E (see FIG. 2). Due to the contact with the friction member, a large frictional force is generated between the pulley holder 12 and the chassis 16 to attenuate the vibration. That is, in particular, the vibration phenomenon is not propagated to the carriage 1 and is also suppressed to the balance weight 17 without being propagated.

  The characteristic graph of FIG. 3 shows the damping effect on the generated vibration. With respect to the magnitude of vibrations generated by the disturbances in the carriage 1 due to the frequencies f1 and f2, the horizontal axis of the graph represents frequency and the vertical axis of graph represents gain. As described above, the frequency f1 is a frequency when the carriage vibration becomes maximum when there is no weight, and the frequency f2 is a frequency when the carriage vibration becomes excessive when there is a weight. In the graph, a case where the amount of vibration attenuation of the pulley holder 12 is small is represented by a solid line, and a case where the amount of attenuation is large is represented by a dotted line.

  As is apparent from FIG. 3, when the vibration attenuation amount of the pulley holder 12 is small, excessive vibrations with the frequencies f1 and f2 are generated in the carriage 1. Further, when the vibration attenuation amount of the pulley holder 12 is large, excessive vibration due to only the frequency f1 occurs in the carriage 1. That is, by increasing the amount of vibration attenuation of the pulley holder 12, excessive vibration due to the frequency f2 can be suppressed in the carriage 1 even when the balance weight 17 is attached. In other words, as the frictional resistance is increased through the friction member in the contact region E (see FIG. 2), an excessive vibration phenomenon caused by f2 of the carriage 1 due to the vibration of the balance weight 17 can be suppressed. Synergistically with this action, the balance weight 17 effectively functions to attenuate the vibration, and the vibration of the carriage 1 is suppressed to enable recording of high print quality.

(Carriage vibration isolator)
-Second Embodiment-
FIG. 4 shows an application example of the pulley holder vibration damping unit in the belt tension mechanism as the second embodiment. That is, in this case, the vibration damping damper 19 is attached to the pulley holder 12. As the damper 19, for example, a dashpot type shock-absorbing / vibration-proof mechanism using air pressure by a cylinder and a piston can be employed. Also in the present embodiment, the vibration due to the frequency f2 generated by the balance weight 17 is also effectively suppressed as in the case of the first embodiment.

The perspective view which shows 1st Embodiment of a carriage vibration isolator. The perspective view which shows the pulley holder vibration attenuation part with which the belt tension | tensile_strength mechanism was mounted | worn as 1st Embodiment. The graph which shows the vibration damping characteristic of this embodiment. The perspective view which shows the pulley holder vibration attenuation part by 2nd Embodiment. The figure which shows typically the vibration form in the conventional carriage mechanism. The figure which shows typically the vibration form in the conventional carriage mechanism similarly. The graph which shows the conventional carriage vibration characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carriage 4,5 Guide shaft 6 Carriage pulling belt 9 Drive pulley 10 Driven pulley 11 Drive source motor 12 Pulley holder 13 Tension spring (elastic member)
16 Chassis 17 Balance weight 18 Pulley holder guide 19 Dashpot type damper for vibration damping (pulley holder vibration damping part)
E Contact area with friction member (pulley holder vibration damping part)

Claims (3)

A carriage that carries a recording head that ejects ink and records an image on a sheet of a recording material and reciprocates in a scanning direction, a belt that pulls and moves the carriage, and a carriage that is attached to the belt and that is attached to the carriage A balance weight that moves in the opposite direction to reduce the reaction force due to the movement of the belt, a driven pulley that stretches the belt and forms a pair with the drive pulley, and in a state where the driven pulley is rotatably held in the belt stretching direction. A movable pulley holder, a chassis that movably supports the pulley holder, and an elastic member that is attached to the chassis and biases the pulley holder in a direction that applies tension to the belt. In the device
A carriage vibration isolator comprising a pulley holder vibration attenuating portion for attenuating vibration of the pulley holder provided in the chassis.   The pulley holder vibration attenuating portion is provided with a friction member that increases frictional resistance on at least one of the contact surface of the pulley holder and the chassis in a contact region where the pulley holder moves in contact with the chassis. The carriage vibration isolator according to claim 1.   2. The carriage vibration damping device according to claim 1, wherein the pulley holder vibration damping unit includes a dashpot type vibration damping damper having both ends locked to the pulley holder and the chassis.

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