JP2004136669A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure high quality printing regardless of the thickness of a recording medium. <P>SOLUTION: A rack 41 formed on an L-shaped lever 35 meshes with two gears 30. Each gear 30 is inserted, at an eccentric position, with the forward end part of a guide rod, i.e. inserting part 18a, 19a. A carriage 20 fixed with an ink jet head 21 is supported by two guide rods. When a knob 42 is moved to the left and right, the two gears 30 are turned to move the two guide rods up and down. Consequently, the gap G between the ink ejection surface of the ink jet head 21 and the conveying surface of a conveyor belt 25 is varied. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an ink jet recording apparatus including an ink jet head for discharging ink onto a recording medium.

2. Description of the Related Art There is known a plotter that records on paper with a pen while moving the pen by pulling a carriage on which the pen is mounted with a belt. As a technique for reciprocating the carriage in one direction in such a plotter, Patent Document 1 discloses a technique in which the carriage is supported by two guide rails. When this technology is applied to a serial printing type ink jet printer, a configuration is obtained in which a carriage on which an ink jet head is mounted reciprocates along a guide rail while being supported by two guide rods. In this case, the distance from the ink ejection surface of the inkjet head to the recording medium conveyance surface is constant.

Japanese Patent No. 2797637

However, recording media used in ink jet printers have various thicknesses. Therefore, the distance from the ink ejection surface to the surface of the recording medium facing the ink ejection surface varies according to the thickness of the recording medium. Therefore, if the thickness of the recording medium changes, the print quality also changes, and the print quality becomes unstable.

主 A main object of the present invention is to provide an ink jet recording apparatus capable of printing with high quality regardless of the thickness of a recording medium.

An inkjet recording apparatus according to an aspect of the invention includes an inkjet head having an ink ejection surface on which a plurality of nozzles are arranged, a medium transport mechanism that forms a transport surface on which a recording medium is transported, and the ink ejection surface facing the transport surface. And a carriage driving mechanism including a carriage to which the inkjet head is attached, and a plurality of parallel guide rods supporting the carriage and extending in a direction intersecting with a recording medium conveyance direction by the medium conveyance mechanism. A carriage drive mechanism for reciprocating the carriage along the guide rod, and a guide drive mechanism for moving the plurality of guide rods in a direction in which a distance between the ink ejection surface and the transport surface changes. Have.

According to this, the distance from the ink ejection surface to the surface of the recording medium facing the ink ejection surface can be kept constant. Therefore, high-quality printing can be performed on recording media having various thicknesses. Further, even when a recording medium having a considerably large thickness is used, the recording medium is unlikely to be rubbed or caught on the ink ejection surface of the inkjet head, so that it is possible to suppress the occurrence of stains and jams on the recording medium.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the ink jet printer 1 according to one embodiment of the present invention is a serial printing type in which a carriage 20 reciprocates right and left in FIG. The carriage 20 supports the two inkjet heads 21 so that the ink ejection surface 21a in which a large number of nozzles are arranged in a matrix is horizontal. The inkjet head 21 has a rectangular planar shape, and its longitudinal direction is orthogonal to the moving direction of the carriage 20. The inkjet head 21 has a length of, for example, about 10 cm or more, and is longer than nozzles arranged inline in one or two rows. In FIG. 1, illustration of a medium transport mechanism such as a transport belt 25 to be described later is omitted.

孔 As shown in FIG. 3, holes 20a and 20b having circular cross sections are provided near both ends of the carriage 20 along the longitudinal direction of the inkjet head 21, respectively. Cylindrical guide rods 18 and 19 are fitted into the holes 20a and 20b so as to support the carriage 20 so as to be slidable. The guide rods 18 and 19 are supported at both ends by side frames 2 and 3 which are plates erected in the vertical direction outside the conveyor belt 25 so as to be parallel to each other. As described later, the guide rods 18 and 19 are supported by the side frames 2 and 3 so that the height thereof can be changed. The side frames 2 and 3 are connected by a front frame 4.

The carriage drive shaft 5 is supported at the same height position as the guide bars 18 and 19 outside the side frame 2 so as to be orthogonal to the guide bars 18 and 19. At the same height position as the guide rods 18 and 19 outside the side frame 3, the connecting shaft 6 is supported so as to be orthogonal to the guide rods 18 and 19. That is, the two shafts 5 and 6 are arranged in a direction parallel to the direction in which the sheet as the recording medium is conveyed (hereinafter, “sheet conveying direction”).

The carriage drive motor 7 is attached to the front frame 4 below the guide rods 18 and 19. A pulley 9 is fixed to the output shaft 8 of the carriage drive motor 7 by being fitted therein. Since the endless belt 11 is stretched between the pulley 9 and the pulley 10 fixed by being fitted into one end of the carriage drive shaft 5, the carriage drive shaft 5 rotates with the rotation of the output shaft 8. .

Two toothed drive pulleys 12 and 13 are fixed to the carriage drive shaft 5. Two driven pulleys 14 and 15 having teeth are fixed to the connection shaft 6 at positions corresponding to the drive pulleys 12 and 13. Carriage drive belts 16 and 17, which are endless belts, are stretched between the drive pulley 12 and the driven pulley 14 and between the drive pulley 13 and the driven pulley 15, respectively. The carriage drive belts 16, 17 extend at the same height as the guide rods 18, 19 in parallel with them. The four pulleys 12, 13, 14, 15 all have the same outer diameter. Therefore, by driving the carriage drive motor 7 forward and backward, the carriage drive belts 16 and 17 can be driven to rotate at the same speed in both the clockwise direction and the counterclockwise direction in FIG.

As shown in FIGS. 2 and 3, fixing portions 23 and 24 are provided outside the holes 20 a and 20 b of the carriage 20. The carriage 20 is fixed to the carriage drive belts 16 and 17 at fixing portions 23 and 24. Therefore, the carriage 20 can be reciprocated in the direction along the guide rods 18 and 19 (the direction of the thick arrow in FIG. 2) by driving the carriage drive motor 7 forward and backward. As described above, by using the two guide rods 18 and 19, the carriage 20 supporting the long inkjet head 21 can run stably.

As shown by a two-dot chain line in FIG. 3, a transport belt 25 which is an endless belt for transporting the recording medium in a direction orthogonal to the guide rods 18 and 19 is provided at a position facing the ink ejection surface of the inkjet head 21. Is provided. The transport belt 25 is wound around two rollers 26 and 27. When a driving force from a motor (not shown) is transmitted to one of the rollers 26, the recording medium is held along the transport surface 25a of the transport belt 25 while the recording medium is held along the transport surface 25a. 3 can be conveyed in the white arrow direction.

Next, the support structure of the guide rods 18 and 19 will be described with reference to FIGS. As shown in FIG. 2, columnar insertion portions 18a, 18b, 19a, and 19b having outer diameters smaller than inner portions thereof are provided at both ends of the guide rods 18 and 19, respectively. The inserts 18a, 18b, 19a, 19b are concentric with the inner part.

As shown in FIG. 5, the insertion portion 19a is inserted into a shaft support hole 33 (having a diameter larger than the outer diameter of the insertion portion 19a and smaller than the outer diameter of the guide rod 19) formed in the side frame 3. Thus, the whole protrudes from the side frame 3 to the outside. The insertion portion 19a protruding from the shaft support hole 33 is press-fitted into a support hole 34 formed in the gear 30, which is a rotating member. The center of the support hole 34 is a position eccentric to the rotation center of the gear 30.

The gear 30 is composed of a tooth portion 31 having teeth provided on the outer periphery, and a boss portion 32 projecting from the tooth portion 31 in the axial direction. The boss portion 32 is located between the inner peripheral surface of the shaft support hole 33 formed in the side frame 3 and the outer peripheral surface of the insertion portion 19a. The insertion portions 18a, 18b, and 19b are also supported by the side frames 2 and 3 using the gear 30 in the same configuration as the insertion portion 19a is supported by the side frame 3.

As shown in FIGS. 4 and 5, an elongated L-shaped bar 35 is supported on the side frame 3 on the outer side and above the gear 30 in a direction along the sheet conveying direction. The L-shaped bar 35 has an L-shaped cross section, and has two long holes 36 long at both ends in a direction along the sheet transport direction. A boss member 37 having an outer diameter slightly smaller than the width of the long hole 36 is fitted into each long hole 36. Then, the screw 38 fitted in the boss member 37 is fixed to the side frame 3, so that the L-shaped bar 35 is moved by a length of the elongated hole 36 in the paper transport direction with respect to the side frame 3. It can be displaced in the direction along. On both sides of the L-shaped bar 35 in the moving direction, stoppers 39 and 40 for regulating the movement of the L-shaped bar 35 to define the moving range of the L-shaped bar 35 are arranged.

A rack 41 is formed on a lower side surface near both ends of the L-shaped bar 35 over a range longer than the elongated hole 36. The rack 41 meshes with the teeth 31 formed on the outer periphery of the gear 30. As a result, the gear 30 attached to the insertion portion 18a and the gear 30 attached to the insertion portion 19a are connected via the L-shaped bar 35. That is, as the L-shaped bar 35 moves left and right, the two gears 30 rotate together. When connecting these two gears 30, adjustment is performed so that the rotation phases of the support holes 34 match.

A substantially column-shaped knob 42 is provided at the center in the longitudinal direction of the L-shaped bar 35 so as to protrude upward. Therefore, the L-shaped bar 35 can be easily slid along its longitudinal direction by grasping the knob 42 and moving it to the left and right.

In the present embodiment, the same member as the L-shaped bar 35 is not attached to the side frame 2. Therefore, the gear 30 attached to the insertion portion 18b and the gear 30 attached to the insertion portion 19b are not connected. Therefore, these two gears 30 may be simple eccentric cams having no teeth on the outer peripheral surface. However, when a member similar to the L-shaped bar 35 is attached to the side frame 2, the member connects the gear 30 attached to the insertion portion 18b and the gear 30 attached to the insertion portion 19b. You may.

Since the support structure of the guide rods 18 and 19 as described above is employed, the distance between the ink ejection surface 21a of the inkjet head 21 and the conveyance surface 25a changes with the sliding of the L-shaped bar 35. Can be done. Hereinafter, the operation when the knob 42 attached to the L-shaped bar 35 is operated will be described with reference to FIGS.

As shown in FIG. 6 which is an enlarged side view of the vicinity of the insertion portion 19a in FIG. 4, the center A1 of the insertion portion 19a and the guide bar 19 is shifted from the center O of the gear 30. Therefore, when the gear 30 is rotated by the sliding of the L-shaped bar 35, the centers of the insertion portion 19a and the guide bar 19 move from A1 to A2. Accordingly, the guide bar 19 moves from the position drawn by the broken line to the position drawn by the two-dot chain line. With this movement, the height of the guide rod 19 changes by the displacement amount H. The guide rod 18 connected to the guide rod 19 via the two gears 30 and the L-shaped bar 35 also moves by the same amount in the same direction as the guide rod 19. Therefore, the carriage 20 supported by the two guide rods 18 and 19 changes its height by the height displacement amount H of the guide rods 18 and 19. In this manner, the distance (gap G shown in FIG. 7) between the ink ejection surface 21a of the inkjet head 21 and the transport surface 25a can be changed.

FIG. 7 shows a state in which the knob 42 of the L-shaped bar 35 is moved from right to left. In the state of FIG. 7, the knob 42 is at the right position. At this time, the gap between the ink ejection surface 21a and the transport surface 25a (indicated by the symbol “G” in FIG. 7) is relatively narrow. When the knob 42 is moved to the left from this state, the L-shaped bar 35 also moves integrally, and the rack 41 formed on the L-shaped bar 35 rotates the two gears 30 simultaneously. Then, as described above, the height of the two guide rods 18 and 19 simultaneously changes by the displacement amount H with the rotation of the gear 30. Since the carriage 20 is supported by the guide rods, the gap G is enlarged by the same amount as the height displacement H of the guide rods 18 and 19.

A brief description will be given of a printing operation on a recording medium in the inkjet printer 1 configured as described above. In the initial state, the distance between the ink ejection surface 21a and the transport surface 25a is adjusted by operating the knob 42 in advance, and the surface of the recording medium is moved from the ink ejection surface 21a regardless of the thickness of the recording medium on which printing is performed. Is set as a predetermined distance. When the printing operation is started, the recording medium sent to the transport belt 25 from a paper feed cassette (not shown) on the left side in FIGS. It passes through a gap G formed between the lower surface of the head 21, ie, the ink ejection surface 21a, and the upper surface of the transport belt 25, ie, the transport surface 25a. In parallel with this, ink is ejected from the nozzles formed on the ink ejection surface 21a while the carriage 20 reciprocates in the width direction of the recording medium (the direction of the thick arrow in FIG. 2). As a result, a desired image is formed on the upper surface of the recording medium.

As described above, according to the present embodiment, the gap between the ink ejection surface 21a and the transport surface 25a can be adjusted while maintaining the parallelism between them. Therefore, the gap between the ink ejection surface 21a and the conveyance surface 25a should be increased for a recording medium having a large thickness, and the gap between the ink ejection surface 21a and the conveyance surface 25a should be decreased for a recording medium having a small thickness. Accordingly, the distance between the ink ejection surface 21a and the surface of the recording medium can be adjusted to be constant. Therefore, printing can be performed with high print quality on both recording media having different thicknesses, such as a simple recording medium and a double envelope. Further, even when a recording medium having a considerably large thickness is used, it is possible to prevent the recording medium from being rubbed or caught on the ink ejection surface 21a of the inkjet head 21. Therefore, it is possible to greatly reduce the occurrence of stains and jams on the recording medium.

(4) The gap between the ink ejection surface 21a and the conveyance surface 25a can be adjusted with a simple configuration in which the guide rods 18 and 19 are supported at the eccentric position of the gear 30, which is excellent in practicality. Moreover, only the L-shaped bar 35 is slid, which is excellent in operability. Further, since the rack 41 is formed on the L-shaped bar 35, the gear 30 is rotated by the engagement between the rack 41 and the teeth 31 of the gear 30, and the reliability is high.

Furthermore, since the L-shaped bar 35 can rotate the two gears 30 simultaneously, the operation is further facilitated. In addition, since the L-shaped bar 35 is provided with the knob 42, it is easy for the user to operate. Since the guide rods 18 and 19 are supported by the gear 30 at both ends, the height of the guide rods 18 and 19 hardly fluctuates, and the height stability is excellent.

In addition, since the carriage 20 can be moved by the carriage driving belts 16 and 17 parallel to the guide rods 18 and 19, the gap between the ink ejection surface 21a and the conveyance surface 25a almost always varies depending on the position of the carriage 20. Absent.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various design changes can be made within the scope of the claims. For example, in the above-described embodiment, a mechanism having the belt 25 is employed as a transport mechanism for transporting the recording medium. However, the transport means is not limited thereto, and a roller having a cylindrical surface as a transport surface, a roller pair, or the like. A mechanism for transporting the recording medium while sandwiching the recording medium may be used. Further, the L-shaped bar 35 may be provided for each gear 30, and the two gears 30 may not be connected.

Furthermore, the mechanism for moving the guide rod is not limited to the mechanism described above, and various mechanisms can be adopted. As the recording medium, paper, plastic film, and the like can be used. The point is that the sheet is flexible and any sheet can be used as long as an image can be recorded on one side of the sheet by an ink jet head. Instead of the L-shaped bar 35, for example, the two gears 30 may be connected by winding an endless belt around the two gears 30. Further, in the above-described embodiment, the present invention has been described by taking an inkjet printer as an example. However, the present invention is also applicable to a printing apparatus such as a facsimile or a copier equipped with an inkjet head.

FIG. 1 is a schematic front view of an inkjet printer according to an embodiment of the present invention. FIG. 2 is a bottom view of the ink jet printer shown in FIG. 1. FIG. 2 is a side view of the vicinity of a carriage included in the ink jet printer shown in FIG. 1. FIG. 2 is a partial side view of the inkjet printer shown in FIG. 1. FIG. 5 is a sectional view taken along the line VV of FIG. FIG. 5 is an enlarged side view around the gear illustrated in FIG. 4. FIG. 2 is a side view of the ink jet printer shown in FIG. 1.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Ink jet printer 2, 3 Side frame 4 Front frame 5 Carriage drive shaft 6 Connecting shaft 7 Carriage drive motor 8 Output shaft 9, 10 Pulley 11 Endless belt 12, 13 Drive pulley 14, 15 Follower pulley 16, 17 Carriage drive belt 18 , 19 Guide rods 18a, 18b, 19a, 19b Insertion section 20 Carriage 20a, 20b hole 21 Inkjet head 21a Ink ejection surface 23, 24 Fixing part 25 Conveyor belt 25a Conveyor surface 26, 27 Roller 30 Gear 31 Teeth 32 Boss 33 Shaft Support hole 34 Support hole 35 L-shaped bar 36 Slot 37 Boss member 38 Screw 39, 40 Stopper 41 Rack 42 Knob

Claims (10)

An inkjet head having an ink ejection surface on which a plurality of nozzles are arranged,
A medium transport mechanism that forms a transport surface on which a recording medium is transported,
A carriage to which the inkjet head is attached such that the ink ejection surface faces the transport surface,
A carriage driving mechanism that supports the carriage and includes a plurality of parallel guide rods extending in a direction intersecting with a recording medium transport direction by the medium transport mechanism, and the carriage drive mechanism moves the carriage along the guide rods. A carriage drive mechanism for reciprocating movement,
An ink jet recording apparatus comprising: a guide drive mechanism for moving the plurality of guide bars in a direction in which a distance between the ink ejection surface and the transport surface changes. The guide drive mechanism is
A rotatable rotating member that supports the guide bar at an eccentric position,
The ink jet recording apparatus according to claim 1, wherein the rotation member has a point different from the eccentric position as a rotation center, and moves the guide rod by rotating the rotation member. The guide drive mechanism is
3. The ink jet recording apparatus according to claim 2, further comprising a rotating force applying member that applies a rotating force to the rotating member. The inkjet recording apparatus according to claim 3, wherein the rotational force applying member applies a rotational force to each of the rotating members related to the plurality of guide rods. The inkjet recording apparatus according to claim 3 or 4, wherein the rotational force applying member is a slidable rod-shaped member. 6. The ink jet recording apparatus according to claim 5, wherein the rotating member is a gear, and the bar is provided with a rack that meshes with the gear. 7. The ink jet recording apparatus according to claim 6, wherein a knob is attached to the rotational force applying member. The inkjet recording apparatus according to any one of claims 2 to 7, wherein each guide rod is supported by two of the rotating members. The carriage drive mechanism is
A plurality of pairs of pulleys having a rotation axis in a direction orthogonal to the guide rod, wherein each pair of two pulleys is separated along the guide rod;
The inkjet recording apparatus according to any one of claims 1 to 8, further comprising a plurality of carriage drive belts spanned over the plurality of pairs of pulleys. An inkjet head having an ink ejection surface on which a plurality of nozzles are arranged,
A medium transport mechanism that forms a transport surface on which a recording medium is transported,
A carriage that holds the inkjet head such that the ink ejection surface faces the transport surface,
A pair of parallel guide rods supporting the carriage, a gear supporting one end of the guide rod at an eccentric position, an eccentric cam provided at the other end of the guide rod and having the same size as the gear; A guide drive mechanism comprising: a pair of gears that support one end of the pair of guide rods and a rack that meshes with each other and is slidable in the rotation direction of the gears, wherein the gears are rotated by sliding the racks. And a guide driving mechanism that moves the pair of guide rods and adjusts a distance between the ink ejection surface and the transport surface.

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