JP2011121223A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus that prevents vibration or floating of a recording medium in recording areas, maintaining a distance between a recording head and the recording medium, thereby preventing deteriorated images regardless of changes of use environment. <P>SOLUTION: The inkjet recording apparatus includes: a recording head 1 that ejects ink; a platen 3 that is arranged to face the recording head; and a pair of rollers 2, 2 that are provided in feeding upstream and downstream sides of the recording head. Each of the pairs of rollers 2 have a drive roller 5 to be driven and rotated; driven rollers 4a, 4b that are pressed by the drive roller in the feeding upstream and downstream sides to a center vertical line 9 of the drive roller. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that includes a recording head that ejects ink and a platen that is disposed at a position facing the recording head.

  In the ink jet recording apparatus, since the recording surface of the recording medium is not directly touched in the recording area, the recording medium may flutter or float in the recording area, which may cause the image quality to deteriorate. In particular, in a full-line type ink jet recording apparatus, when a plurality of line type recording heads are arranged in the recording medium conveyance direction, the distance from the most upstream recording head to the most downstream recording head becomes long, and the recording medium floats. Is likely to occur, which may cause disturbance of the recorded image and jam of the recording medium.

  Therefore, a method for preventing the floating by urging the recording medium downward has been proposed. For example, Patent Document 1 discloses a method of adsorbing a recording medium with electrostatic force by applying an electric charge to an electrode arranged in a recording area. Patent Document 2 discloses a method of urging the recording medium downward by pressing the driven roller toward the downstream side of the conveyance roller from the center vertical line of the drive roller in a pair of conveyance rollers including a drive roller and a driven roller. ing.

Japanese Patent Application Laid-Open No. 11-151843 JP 2002-128312 A

  Ink jet recording apparatuses are required to convey (paper feed) while maintaining a constant distance between the recording head and the recording medium in order to perform recording with high image quality. In addition, when performing borderless recording, the leading and trailing ends of the recording medium cannot be pressed by a roller, and image quality is likely to deteriorate due to flapping or floating of the recording medium. Therefore, there is a higher demand for urging the recording medium downward. However, the belt suction method of Patent Document 1 has a problem that the suction force is reduced due to a change in suction conditions due to a change in use environment, in addition to a complicated configuration. Further, in the configuration in which the driven roller in Patent Document 2 is moved downstream and pressed against the driving roller, it is possible to reduce the fluttering of the recording medium downstream of the driving roller, but the rear end portion after passing through the driving roller. It was difficult to reduce fluttering.

  The present invention has been made in view of such technical problems. SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus capable of suppressing fluttering and floating of a recording medium in a recording area regardless of a change in use environment, and preventing deterioration in image quality by keeping the distance between the recording head and the recording medium constant. Is to provide.

  The present invention is an ink jet recording apparatus that includes a recording head that ejects ink and a platen that is disposed at a position facing the recording head, and is disposed upstream and downstream of the recording head. A pair of rollers, wherein the pair of rollers includes a driving roller that is driven to rotate, and a driven roller that is pressed by the driving roller on the upstream side and the downstream side of the center of the driving roller. To do.

  According to the present invention, there is provided an ink jet recording apparatus that can suppress fluttering or floating of a recording medium in a recording area regardless of a change in use environment, and can prevent deterioration in image quality of a recorded image.

Side view of inkjet recording apparatus according to one embodiment Side view showing conveyance of recording medium in recording area Block diagram of control system Plan view and sectional view showing arrangement of driven roller with respect to drive roller A plan view and a cross-sectional view showing a modified example of the arrangement of the driven roller with respect to the drive roller

  Embodiments of the present invention will be specifically described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 1 is a side view of an ink jet recording apparatus according to an embodiment. The ink jet recording apparatus includes a paper feed unit 11, a recording unit 12, a transport unit 13, and a paper discharge unit 14. The paper feed unit 11 is provided with a pickup roller 11a for drawing a sheet-like recording medium P such as paper in the transport direction, and a feed roller 11b and a reverse roller 11c for separating and transporting the recording medium P one by one. Has been.

  The recording unit 12 is provided with a recording head 1 that performs recording by ejecting ink from nozzles (ejection ports) based on image information. In the present embodiment, a full-line type ink jet recording head having a nozzle row composed of a plurality of nozzles arranged in a direction crossing the conveyance direction of the recording medium P is used. The illustrated recording unit 12 is for color recording, and from the upstream side of conveyance of the recording medium P, there are four recording heads: a black recording head 1K, a cyan recording head 1C, a magenta recording head 1M, and a yellow recording head 1Y. The recording heads are sequentially arranged at predetermined intervals. As these recording heads, for example, an ink is used which causes ink to boil with a built-in heater and ejects ink from nozzles by pressure change caused by the growth or contraction of bubbles due to this film boiling.

  The conveyance unit 13 includes a recording medium detection sensor 10 for detecting a recording medium, four platens 3 disposed at positions (directly below) facing the four recording heads, and four platens 3 respectively. And five sets of roller pairs 2 arranged at approximately equal intervals at five locations on the outermost platen and between the uppermost stream and the lowermost stream of the transport. The five roller pairs 2 are also arranged at approximately equal intervals between the four recording heads 1K, 1C, 1M, and 1Y and at five locations outside the recording head that is the most upstream and downstream of the conveyance. It has become. That is, each of the four recording heads includes a roller pair disposed on the upstream side and the downstream side of the transport. The paper discharge unit 14 is configured to discharge the recording medium P on which an image has been formed by the recording unit 12 to a paper discharge tray 14c by a paper discharge roller 14a as a driving roller and a spur 14b as a driven rotating body.

  FIG. 2 shows an arbitrary recording head 1, a platen 3 facing the recording head, and two sets of roller pairs 2 arranged on both sides of the platen in the conveyance direction (also on both sides in the conveyance direction of the recording head). It is a side view which takes out and shows. Next, the conveyance of the recording medium P in the recording area will be described with reference to FIG. On both sides of the recording head 1, a pair of rollers 2 are arranged with a predetermined distance apart, and a platen 3 is disposed under the recording head 1. Each roller pair 2 is composed of a driving roller (conveying roller) 5 that is driven and rotated by the drive of a motor, and driven rollers 4a and 4b that are pressed against two locations on the circumference of the driving roller. The two driven rollers 4 a and 4 b are pressed by the driving roller 5 on the upstream side and the downstream side of the conveyance with respect to a vertical line (referred to as a central vertical line) 9 passing through the center of the driving roller 5. With the arrangement of the driven rollers 4a and 4b, the conveyed recording medium P is urged downward (toward the platen 3) from the front end to the rear end as shown in FIGS. . As a result, in the recording area composed of the opposed areas of the four recording heads, the recording medium is prevented from flapping or floating over the entire area from the front end to the rear end. It is possible to form a high-quality image by keeping the interval at a constant.

  FIG. 3 is a block diagram of a control system of the ink jet recording apparatus. Next, control means for controlling driving of each unit such as the recording unit 12 and the conveyance unit 13 will be described. The control unit 20 that sends out drive control signals for each unit includes a CPU 20a, a ROM 20b, a RAM 20c, and a counter 20d. The CPU 20a is a central processing unit, and reads out programs and various data from the ROM 20b and the like, performs necessary calculations and determinations, and controls each unit. The ROM 20b is a read-only memory, and stores various programs and character codes for operating the CPU 20a, and various data necessary for dot pattern recording. The RAM 20c is a read / write memory, and has a working area for temporarily storing data in a command from the CPU 20a and a calculation result, a buffer area for storing various data input from the external device 22 and the like. The counter 20d counts the number of driving pulses of the carry motor 26 and transmits the information to the CPU 20a.

  An image signal from the external device 22, a recording medium detection signal from the recording medium detection sensor 10, and the like are input to the control unit 20 via the control interface 23. Further, the control unit 20 outputs a drive signal to the motor driver 24 for driving the transport motor 26 or outputs a drive signal to the head driver 25 for driving the recording head 1 based on the program. .

  4 is a view showing the arrangement of the driven rollers 4a and 4b with respect to the drive roller 5, FIG. 4 (a) is a plan view, and FIG. 4 (b) is a view taken along line bb in FIG. 4 (a). It is the center part longitudinal cross-sectional view. The driven roller 4a is constituted by a plurality of roller portions 8e divided in the axial direction, and the driven roller 4b is constituted by a plurality of roller portions 8f divided in the axial direction. The driven rollers 4a and 4b are arranged in a staggered manner in the axial direction in the plurality of roller portions 8e and roller portions 8f that are alternately arranged on the upstream side and the downstream side with respect to the center vertical line 9 of the driving roller 5. The roller portion 8e and the roller portion 8f are formed. The roller portions 8e and 8f that are driven to rotate are rotatably supported by shafts 81e and 81f that are arranged in a staggered manner in the front-rear direction with respect to the center vertical line of the drive roller 5. The plurality of roller portions 8e and 8f are preferably arranged equally and symmetrically in the axial direction with respect to the transport center 7 as shown in the drawing. By arranging them equally and symmetrically, the conveyance skew (skew, distortion and twist) of the recording medium P is reduced.

  FIG. 5 is a view showing a modification of the arrangement of the driven rollers 4a and 4b with respect to the drive roller 5, FIG. 5 (a) is a plan view, and FIG. 5 (b) is a line b- in FIG. 5 (a). It is the center part longitudinal cross-sectional view seen from b. Also in this modified example, the driven rollers 4a and 4b are alternately offset in a staggered manner on the upstream side and the downstream side of the transport with respect to the center vertical line 9 of the drive roller 5. However, in this modified example, the driven roller 4a is constituted by a plurality of roller portions 8a and 8b divided in the axial direction, and the driven roller 4b is constituted by a plurality of roller portions 8c and 8d divided in the axial direction. . The plurality of roller portions 8a and 8b constituting the driven roller 4a are alternately arranged at positions shifted in the transport direction. That is, the shaft 81a of a part of the roller portion 8a on the downstream side of the center vertical line 9 is pivotally supported at a position slightly shifted to the downstream side of the transport from the shaft 81b of the other roller portion 8b. Further, the plurality of roller portions 8c and 8d constituting the driven roller 4b are also arranged at positions shifted alternately in the transport direction. That is, the shaft 81d of a part of the roller portion 8d on the upstream side of the center vertical line 9 is pivotally supported at a position slightly shifted to the upstream side of the transport from the shaft 81c of the other roller portion 8c. Other configurations of the ink jet recording apparatus according to the modified example of FIG. 5 are the same as those of the embodiment described with reference to FIGS.

  Also in this modified example, the group of roller portions 8a and 8b and the group of roller portions 8c and 8d that are offset in the front-rear direction with respect to the center vertical line 9 of the drive roller 5 are arranged with respect to the transport center 7 as shown in the drawing. It is preferable to arrange them equally and symmetrically in the direction. By arranging them equally and symmetrically, the conveyance skew (skew, distortion and twist) of the recording medium P is reduced.

  According to the configuration of the embodiment described above, as shown in FIG. 1, the recording medium P being conveyed can be urged downward from both sides of the front end portion and the rear end portion of each platen 3. Can be uniformly adhered over the entire region from the front end portion to the rear end portion. According to the modified example of FIG. 5, the recording medium can be more uniformly and evenly adhered. Therefore, even in a configuration in which a plurality of recording heads are arranged in parallel in the transport direction, fluttering and floating of the recording medium in the recording area can be suppressed, and the distance between the recording head and the recording medium can be kept constant to maintain the recording image. Image quality deterioration can be prevented. Thus, there is provided an ink jet recording apparatus that can suppress fluttering and floating of the recording medium in the recording area regardless of changes in the use environment, and can prevent deterioration in the image quality of the recorded image.

  In the above embodiment, the line type recording apparatus using only the sub-scanning by transporting the recording medium has been described. However, the present invention can be similarly applied to other recording systems such as a serial type that performs main scanning with a recording head. It is. Further, the present invention can be similarly applied regardless of the number of recording heads. In addition, the present invention can be similarly applied regardless of the type of recording medium, such as a cut sheet cut to a certain size or a long sheet such as roll paper. Furthermore, the present invention can be similarly applied regardless of the material of the recording medium such as paper, plastic film, photographic paper, and non-woven fabric.

DESCRIPTION OF SYMBOLS 1 Recording head 2 Roller pair 3 Platen 4a, 4b Driven roller 5 Drive roller 8 Roller part P Recording medium

Claims (4)

An ink jet recording apparatus comprising: a recording head that ejects ink; and a platen disposed at a position facing the recording head,
A roller pair disposed on the upstream side and the downstream side of the recording head;
2. The ink jet recording apparatus according to claim 1, wherein the roller pair includes a driving roller that is driven to rotate and a driven roller that is pressed against the driving roller on the upstream side and the downstream side with respect to a central vertical line of the driving roller.   The inkjet recording apparatus according to claim 1, wherein the driven roller includes a plurality of roller portions divided in an axial direction.   The inkjet recording apparatus according to claim 2, wherein the plurality of roller portions are arranged in a zigzag shape in the axial direction.   The inkjet recording apparatus according to claim 2, wherein a part of the plurality of roller parts is pressed by the driving roller at a position shifted in a transport direction from other roller parts.

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