JP2007045100A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which can suppress the reduction of a local recording grade in such a manner that a mechanism which cancels the displacement of a discharging port by a mutual rotating motion is established even in a driving transmission initial stage. <P>SOLUTION: This inkjet recording device comprises a contact member 18 and an elastic body 1 which press a carriage 2 and a carrier shaft 5. When K is taken as a dimensionless constant of 0.8 to 1.2, Ds is taken as a distance in the sheet carrying direction between a position where a belt 7 is fastened to the carriage 2, and the gravity center of the carriage 2, Dv is taken as a distance in the vertical direction between a position where the belt 7 is fastened to the carriage 2, and the gravity center of the carriage 2, M is taken as the mass of the carriage 2, and g is taken as a gravitational acceleration, the pressing force by the contact member 18 and the elastic body 1 satisfies K×Ds/Dv×M×g. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that performs recording on a recording medium by ejecting ink while scanning a carriage on which a recording head is mounted.

  A conventional inkjet recording apparatus is an apparatus that performs recording by scanning a carriage mounted with a recording head that reciprocates perpendicularly to the conveyance direction of a recording medium such as paper or an OHP sheet. Is a recording method for jetting.

  This ink jet recording apparatus is applied to printers, copiers, facsimiles and the like because of low noise, low running cost, easy miniaturization of the apparatus, and easy colorization. In recent years, the requirements for the material of the recording medium have been diversified, and to a recording apparatus that uses cloth, leather, or metal as a recording medium in addition to paper or resin thin plate (OHP sheet or the like) that is a normal recording medium. Also comes to be used.

  In such an ink jet recording apparatus, the recording head has a fixed interval with respect to the recording medium, and the ink ejected from the recording head flies through the space between the recording head and the recording medium and reaches the recording medium. To record. The recording head is formed with an ejection port (usually a plurality) for ejecting ink, and the size of the ejection port is recently becoming smaller with higher image quality.

  The ink jet recording apparatus is an extremely excellent recording apparatus having a simple configuration, but there is also a technical problem that should be fully considered. In a conventional ink jet recording apparatus, a bearing is always provided between the carriage and a carriage shaft that is mounted so as to scan the carriage in parallel with the surface of the recording medium. Exists.

  Incidentally, the carriage obtains power by transmitting the driving force of the motor by a belt attached to the carriage. As long as the position of the belt attached to the carriage does not exist on the center of gravity of the carriage, when the power is transmitted through the belt, the carriage rotates due to the presence of the backlash.

  Due to the rotational movement of the carriage, the ejection port of the recording head mounted on the carriage has a displacement from a desired recording position, so that the recording quality is lowered. There is a configuration in which the presence of this rattle is improved by providing a carriage and a guide member and pressing and holding to prevent rattling of the carriage (see Patent Document 1).

JP-A-5-85004 (Section 7, FIG. 10)

  FIG. 8 is a perspective view showing a coordinate system (A axis, B axis, C axis) in a conventional ink jet recording apparatus. As shown in FIG. 8, when the power of the motor is transmitted to the carriage 2 via the belt and the carriage 2 scans, the carriage 2 rotates around the carriage scanning direction axis (A axis) due to the presence of backlash, and the sheet conveying direction. A rotational movement around the axis (B axis) and around the axis (C axis) perpendicular to the recording medium is performed. Here, normally, gravity works on the C axis from the recording head to the recording medium.

  The discharge quality of the recording head is lowered by the displacement of the ejection port of the recording head from the desired recording position due to the rotational movement of the carriage 2. Particularly, the deterioration of the recording quality in the scanning direction of the carriage 2 is mainly caused by the displacement of the discharge port due to the rotational movement of the carriage 2 around the B axis and the displacement of the discharge port due to the rotational movement of the carriage 2 around the C axis. ing.

  However, when power is transmitted to the carriage 2 via the belt, the polarity of the displacement of the discharge port due to the rotational motion around the C axis is opposite to the polarity of the displacement of the discharge port due to the rotational motion around the B axis. There is a mechanism to cancel the displacement of the discharge port. The outline is simply shown in FIG.

  As shown in FIG. 9, the overall displacement of the discharge port is the difference between the displacement amount of the discharge port due to the rotational motion about the B axis and the rotational motion about the C axis. However, when there is a difference between the times when the two rotational movements occur, the overall displacement of the discharge port locally increases and the recording quality is lowered. By the way, the rotational movement around the B axis is different from the rotational movement around the C axis due to the influence of gravity, and therefore, the generated time is different.

  Due to this time difference, in the initial stage of drive transmission, the mechanism for canceling the displacement of the discharge port due to the mutual rotational motion does not hold until the rotational motion about the B axis occurs. For this reason, there is a problem that the recording quality is locally deteriorated, and the conventional press holding has a problem that there is no press holding for suppressing the deterioration of the recording quality.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus in which a mechanism for canceling the displacement of the discharge port due to mutual rotational motion is established even in the initial stage of drive transmission, and local deterioration in recording quality can be suppressed.

  In order to solve the above problems, a typical configuration of an ink jet recording apparatus according to the present invention includes a carriage on which a recording head is mounted, and a guide that is mounted so as to scan the carriage in parallel with the recording surface of the recording medium. In an ink jet recording apparatus that includes a member, scans the carriage by transmitting a driving force from a carriage motor to the carriage via a belt, and records on a recording medium by discharging ink, the carriage and the guide K is a dimensionless constant of 0.8 to 1.2, Ds is a distance in the sheet conveyance direction from the position where the belt is fastened to the carriage and the center of gravity of the carriage, Dv Is the vertical distance from the position where the belt and the carriage are fastened to the center of gravity of the carriage, and M is the carriage. Tsu di mass, g is when the gravitational acceleration, the pressing force by the pressing member, characterized in that a K × Ds / Dv × M × g.

  In the ink jet recording apparatus of the present invention, by applying a pressing force to the carriage, there is no difference in the time between the rotational movement around the axis perpendicular to the recording medium and the rotational movement around the axis in the sheet conveying direction, and even at the initial stage of drive transmission, A mechanism that cancels out the displacement of the discharge port due to the rotational movement of the ink is established, and image quality deterioration can be reduced.

[First embodiment]
A first embodiment of an ink jet recording apparatus according to the present invention will be described with reference to the drawings. FIG. 2 is a perspective view of the ink jet recording apparatus according to the present embodiment. As shown in FIG. 2, the ink jet recording apparatus A includes a cartridge 1, a carriage 2, a support plate 3, a flexible substrate 4, a carriage shaft 5, a guide shaft 6, a belt 7, a pulley 9, pulleys 10, 11 and 12, and a discharge roller. 13 and a housing 14.

  The cartridge 1 can be mounted with an ink jet recording head. The carriage 2 carries the cartridge 1 and scans along the carriage shaft 5 and the guide shaft 6. The support plate 3 has an electrical connection (not shown) for supporting the cartridge 1 and transmitting a recording signal to an electrical connection (not shown) of the cartridge 1.

The flexible substrate 4 connects an electrical connection part (not shown) of the support plate 3 and a main body control part (not shown). An electrical command value (a signal for ejecting ink) from the main body is transmitted to the support substrate 3 through the flexible substrate 4 and image recording is performed.

  The carrier shaft 5 and the guide shaft 6 are guide members attached so as to scan the carriage 2 parallel to the recording surface of the recording medium.

  The belt 7 is stretched around pulleys 9 and 10 disposed at both ends of the apparatus. A carriage 2 is fixed to the belt 7. A driving force is transmitted from the carriage motor 11 to the pulley 9 via a mechanism such as a gear, and the belt 2 is rotated so that the carriage 2 scans the recording medium.

  The conveyance roller 12 is driven by a conveyance motor (not shown) and conveys the recording medium. The discharge roller 13 discharges the recording medium on which the image is recorded to the outside of the apparatus. A carriage shaft 5, a guide shaft 6, and the like are fixed to the housing 14, and the above mechanism is configured.

  FIG. 3 is a perspective view of a carriage on which the recording head is mounted. In FIG. 3, arrows A, B, and C are a carriage scanning direction axis (A axis), a sheet conveying direction axis (B axis), and an axis perpendicular to the recording medium (C axis).

  As shown in FIG. 3, power is transmitted from the carriage motor 11 to the carriage 2 by the belt 7, and the carriage 2 is scanned. The optical element 16 attached to the carriage 2 reads the linear scale 15 provided in parallel with the carriage shaft 5 to detect the position of the carriage 2 in the scanning direction.

  By this position detection, the carriage 2 is scanned to a desired recording position, and an ink discharge command signal is generated. In the cartridge 1, the recording head generates heat energy when a current flows through the substrate in contact with the ink, and a foaming phenomenon occurs. Due to this phenomenon, droplets are formed at the ejection port, and the ink is ejected onto a recording medium to perform desired image recording.

  FIG. 4 is a diagram for explaining the pressing of the carriage and the carriage shaft. As shown in FIG. 4, there is a backlash S between the carriage 2 (bearing 2 a) and the carriage shaft 5. One end of the carriage 2 is fixed to an elastic body 19 (L-shaped leaf spring). An abutting member 18 that abuts on the carrier shaft 5 is provided at the other end of the elastic body 19. The contact member 18 and the elastic body 19 constitute a pressing member that presses the carriage 2 and the carrier shaft 5.

  The elastic body 19 generates a pressing force for pressing the carriage 2 and the carriage shaft 5. With this pressing force, the contact member 18 presses the carriage 2 against the carriage shaft 5 in the B-axis direction. Since the carriage 2 and the elastic body 19 are fixed, the elastic body 19 follows the carriage 2 by scanning the carriage 2 in the A-axis direction, and the pressing force is always applied to the carriage 2 and the carriage shaft 5 regardless of the scanning of the carriage 2. Can be generated between.

  The contact member 18 is made of plastic or metal. The elastic body 19 may be a coil spring or the like. The contact member 18 and the elastic body 19 may be integrated. Further, the elastic body 19 may not be fixed to the carriage 2, and may be any configuration that can follow the scanning of the carriage 2.

  When power is transmitted from the carriage motor 11 to the carriage 2 via the pulley 9 and the belt 7, the carriage 2 rotates due to the presence of the play S. By the rotational movement of the carriage 2, the ejection port of the recording head is displaced from the desired recording position, and the recording quality is lowered. Here, the displacement of the discharge port due to the rotational motion around the C axis is opposite to the polarity of the displacement of the discharge port due to the rotational motion around the B axis, and there is a mechanism that cancels out the displacement of the discharge port due to the mutual rotational motion.

  In the conventional ink jet recording apparatus, the rotational motion around the B axis is difficult to rotate compared to the rotational motion around the C axis due to the influence of gravity. For this reason, there is a difference in the generated time between the rotational movement around the C axis and the rotational movement around the B axis.

  In contrast, the ink jet recording apparatus A of the present embodiment applies a pressing force of K × Ds / Dv × M × g to the carriage 2. K is 0.8 to 1.2, Ds is the distance in the sheet conveyance direction from the position where the belt 7 is fastened to the carriage 2 and the center of gravity of the carriage 2, and Dv is the position where the belt 7 and the carriage 2 are fastened and the center of gravity of the carriage 2. , M is the mass of the carriage 2, and g is the gravitational acceleration. As a result, the rotational motion about the B-axis and the rotational motion about the C-axis are equally difficult to generate, and it is possible to eliminate the time difference between the rotational motions of each other.

  As a result, even in the initial stage of drive transmission, a mechanism for canceling the displacement of the discharge port due to the mutual rotational motion is established, and local deterioration in recording quality can be suppressed. The outline is simply shown in FIG. FIG. 5 is a diagram showing the displacement of the ejection port in the ink jet recording apparatus according to the present embodiment. As shown in FIG. 5, the overall displacement of the discharge port is the difference between the displacement amount of the discharge port due to the rotational motion around the B axis and the rotational motion around the C axis, and the occurrence of each rotational motion occurs at the same time. As a result, the overall displacement of the discharge port is reduced, and the deterioration of the recording quality can be suppressed.

  Here, the relationship between the pressing force and the image quality deterioration will be described. FIG. 1 is a diagram showing the relationship between pressing force and image quality degradation. With Ds as the distance L and Dv as the distance L, the image quality deterioration when the pressing force is changed is examined.

  In FIG. 1, the horizontal axis represents pressing force / (product of carriage mass and gravitational acceleration), and the vertical axis represents image quality degradation. When the pressing force / (product of carriage mass and gravitational acceleration) = K is 0.8 or less, the mechanism for canceling the displacement of the discharge port due to the rotational motion is not always established, and the recording quality is deteriorated. Further, when the pressing force / (product of carriage mass and gravitational acceleration) = K is 1.2 or more, it becomes difficult to generate a rotational motion around the C axis, and the recording quality is deteriorated.

  Although not shown in FIG. 1, when the pressing force is further increased (when the value of K is very large), the recording quality does not deteriorate, but other problems such as an increase in sliding load and durability are considered. The need to do it comes out.

  Therefore, by setting K = 0.8 to 1.2, it is possible to determine an optimum pressing force, and it is possible to reduce image quality deterioration without increasing the pressing force unnecessarily.

[Second Embodiment]
Next, a second embodiment of the ink jet recording apparatus according to the present invention will be described with reference to the drawings. FIG. 6 is a view for explaining pressing of the carriage and the carriage shaft according to the present embodiment. About the part which overlaps with said 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 6, the ink jet recording apparatus of the present embodiment is provided with two contact members 18 and two elastic bodies 19 of the ink jet recording apparatus A of the first embodiment in the carriage scanning direction (A-axis direction). Is.

  The total pressing force due to the pressing of the elastic bodies 19a, 19b and the contact members 18a, 18b is K × Ds / Dv × M × g. The contact member 18 and the elastic body 19 are not limited to two, and may be provided in a plurality, for example, n (where n> 0 is an integer). In this case, K × Ds / Dv × M × g / n is the pressing force per elastic body 19.

  Thus, by providing a plurality of contact members 18 and elastic bodies 19, the carriage 2 and the carriage shaft 5 can be stably pressed.

[Third embodiment]
Next, a third embodiment of the ink jet recording apparatus according to the present invention will be described with reference to the drawings. FIG. 7 is a view for explaining pressing of the carriage and the carriage shaft according to the present embodiment. About the part which overlaps with said 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 7, the ink jet recording apparatus of the present embodiment is a member (flexible member) belonging to the carriage 2 instead of the pressing member (contact member 18, elastic body 19) of the ink jet recording apparatus A of the first embodiment. The substrate 4).

  In such a configuration, when the flexible substrate 4 is curved, a pressing force in the direction of the sheet conveyance direction axis (B axis) is generated, and the pressing force (K × Ds / Dv × M × g) shown in the first embodiment is used. As a result, image quality degradation can be reduced. Further, with such a configuration, it is not necessary to provide special members such as the contact member 18 and the elastic body 19, and the manufacturing cost can be suppressed.

It is a figure which shows the relationship between the pressing force concerning 1st embodiment, and image quality degradation. It is a perspective view of an inkjet recording device. FIG. 3 is a perspective view of a carriage on which a recording head is mounted. It is a figure explaining the press of a carriage and a carriage axis | shaft. It is a figure which shows the displacement of the discharge outlet in an inkjet recording device. It is a figure explaining the press concerning the carriage concerning a second embodiment, and a carriage axis. It is a figure explaining the press concerning a carriage concerning a third embodiment, and a carriage axis. It is a perspective view which shows the coordinate system in the conventional inkjet recording device. It is a figure which shows the displacement of the discharge outlet in the conventional inkjet recording device.

Explanation of symbols

A ... Inkjet recording apparatus S ... Backlash 1 ... Cartridge 2 ... Carriage 2a ... Bearing 3 ... Support plate 4 ... Flexible substrate 5 ... Carrier shaft 6 ... Guide shaft 7 ... Belt 9 ... Pulley 10 ... Pulley 11 ... Carrier motor 13 ... Discharge roller 14 ... Housing 15 ... Linear scale 16 ... Optical element 18 ... Contact member 19 ... Elastic body

Claims (5)

A carriage having a recording head and a guide member mounted so as to scan the carriage in parallel with the recording surface of the recording medium, and transmitting a driving force from a carriage motor to the carriage via a belt In an inkjet recording apparatus that records on a recording medium by scanning the carriage and ejecting ink,
A pressing member that presses the carriage and the guide member;
K is a dimensionless constant of 0.8 to 1.2, Ds is a position where the belt is fastened to the carriage and a distance in the sheet conveyance direction to the center of gravity of the carriage, and Dv is a position where the belt and the carriage are fastened. The vertical distance to the center of gravity of the carriage, M is the mass of the carriage, and g is the acceleration of gravity.
An ink jet recording apparatus, wherein a pressing force by the pressing member is K × Ds / Dv × M × g.   The inkjet recording apparatus according to claim 1, wherein a plurality of the pressing members are provided, and a total pressing force due to the pressing of the plurality of pressing members is K × Ds / Dv × M × g.   3. The ink jet recording apparatus according to claim 1, wherein the pressing member and the carriage are not fixed and follow the scanning of the carriage. 4.   The ink jet recording apparatus according to claim 1, wherein the pressing member is a member belonging to the carriage.   5. The pressing member according to claim 1, wherein the pressing member includes a contact member that contacts the guide member and an elastic body that generates a pressing force. The ink jet recording apparatus described.

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