JP2005007899A - Ink jet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a full-line type ink-jet recording apparatus that printing speed is lowered caused by setting of an idle-ejection area separated from a printing area for performing idle ejection of ink droplets, and an idle ejecting action for rotation operation or parallel movement of a head unit. <P>SOLUTION: A recessed idle-ejection recording liquid reservoir 7 for retaining an ink ejected in an idle ejecting action of the head unit 1 is provided at a position opposing the head unit 1 via a sheet conveyance channel 6. When printing to a sheet P1 is finished and the sheet P1 is out of the printing area by a sheet discharge action, and the next sheet P2 has not been supplied to the printing area, heads 1k, 1c, 1m, and 1y of the head unit 1 are driven and idle-ejection ink droplets I are ejected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to a full line type ink jet recording apparatus.

  A serial type inkjet recording apparatus that performs recording by mounting a head composed of an inkjet head on a carriage and moving it in the main scanning direction as an inkjet recording apparatus such as a printer, a facsimile, a copy, etc. that records an image using an inkjet head; There is a line-type ink jet recording apparatus using an ink jet head in which a plurality of nozzles for ejecting ink droplets are arranged over substantially the entire width of a recording area.

  By the way, an ink jet head used in an ink jet recording apparatus performs recording by ejecting recording droplets (hereinafter referred to as “ink droplets”) from nozzles (ejection ports), and is left in a non-recording state. If the ink viscosity in the nozzle increases due to evaporation or the like, and the ink droplet ejection operation is performed as it is, the ejection state is disturbed or the ejection is impossible, and the printing quality is deteriorated.

  Therefore, normally, when a non-ejection nozzle that does not eject ink droplets at regular intervals or for a certain period of time is generated, ink droplets are ejected from the nozzle in which the non-ejection state is detected or from all nozzles. The head is recovered in the empty ejection operation for discharging the thickened ink.

For example, in a serial type ink jet recording apparatus, ink droplets are ejected separately from a printing area for recording on paper (meaning that ink droplets adhere to it, not limited to paper). Therefore, a recovery operation is performed by setting an empty discharge region (reliability recovery region) for the purpose and periodically moving the carriage to the empty discharge region (see, for example, Patent Documents 1 to 7).
Japanese Patent Publication No. 7-50204 Japanese Unexamined Patent Publication No. 7-47679 JP-A-7-101085 JP-A-7-13207 JP 7-137268 A Japanese Patent Laid-Open No. 7-17196 Japanese Patent Laid-Open No. 7-81085

  Similarly, in a full-line type ink jet recording apparatus, an empty discharge area for discharging ink droplets is set separately from the printing area, and the empty discharge for receiving the ink discharged in the empty discharge area is received. A recording liquid reservoir is provided, and the head unit consisting of a full-line type ink jet head is rotated or translated to move to the idle ejection area, then the idle ejection operation is performed, and then the head unit is returned to the printing area. I try to let them.

In addition, as described above, for example, as described in Patent Document 8, in the serial type ink jet recording apparatus, ink droplets for the idle ejection operation are attached to the paper, as described above, in which the idle ejection area is not set. Some proposals have been made to reduce the size and improve the printing speed.
JP-A-6-15815

  As described above, in the full-line type ink jet recording apparatus, if the head unit is moved to the idle ejection area in order to perform the idle ejection operation, the time required for the movement operation of the mechanical mechanism is required. If the idle ejection operation is performed during the copying, the printing speed is remarkably lowered, and the high-speed recording which is an advantage of the full line type is impaired.

  In particular, in a full-line type ink jet recording apparatus, the target is 30 to 60 ppm. In such a case, in order to promote the fixing effect of ink droplets, the paper may be heated by a heater or the like. The ink in the nozzles easily evaporates and thickens, and the head recovery operation by the idle ejection operation has to be performed frequently, and a decrease in the printing speed associated with the idle ejection operation becomes a serious problem. Further, since the ink jet recording apparatus is easy to colorize, it includes a plurality of heads that eject ink droplets of each color. However, it is also possible to move and return the head unit including the plurality of heads to the idle ejection region. It becomes complicated.

  Therefore, it is conceivable to apply the method of adhering empty ejection ink to the paper proposed in the serial type ink jet recording apparatus described above to the full line type ink jet recording apparatus.

  However, in a recording apparatus that requires high-quality printing quality, it is not practical to print unnecessary printing ink and printing pattern on paper, which would greatly impair printing quality. When the idle ejection operation is performed frequently, unnecessary ink droplets are ejected to the next sheet every time printing is performed on one sheet of paper, and two sheets of paper are used for printing on one sheet of paper. In the end, the printing speed is remarkably reduced and the paper is wasted.

  The present invention has been made in view of the above points, and an object of the present invention is to enable a head recovery operation by an idle ejection operation without causing a decrease in printing speed.

  In order to solve the above problems, an ink jet recording apparatus according to the present invention is a line type ink jet recording apparatus provided with a head in which a plurality of nozzles for ejecting ink droplets are arranged over substantially the entire width of a recording area. The configuration is such that the idle ejection operation is performed before the printed sheet is removed from the printing area and the next sheet is conveyed to the printing area.

  Here, it is preferable that an empty discharge recording liquid reservoir for holding recording liquid discharged during the empty discharge operation is provided at a position facing the head and the paper conveyance path.

  According to the ink jet recording apparatus of the present invention, the idle discharge operation is performed until the recording-completed sheet is removed from the printing area and the next sheet is conveyed to the printing area. The head recovery operation by the idle ejection operation can be performed without causing a decrease in the copying speed.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view of a main part mechanism part of the ink jet recording apparatus according to the present invention, and FIG. 2 is a main part schematic perspective view of the same mechanism part.
The ink jet recording apparatus includes a head unit 1 in which four heads 1k, 1c, 1m, and 1y, in which a plurality of nozzles that eject ink droplets over substantially the entire width of a recording area, are arranged side by side in the paper conveyance direction. ing. The head unit 1 is arranged with the ink droplet ejection surface 1a of each head facing downward. The four heads 1k, 1c, 1m, and 1y are supplied with ink of each color from an ink tank (not shown) through ink supply pipes 2y, 2m, 2c, and 2k.

  A guide plate 3 for guiding and transporting paper is provided below the head unit 1, a transport roller pair 4 for feeding paper is provided upstream of the head unit 1, and paper is discharged downstream of the head unit 1. The paper discharge roller pair 5 is provided.

  A concave empty discharge recording liquid reservoir 7 for holding ink discharged during the empty discharge operation of the head unit 1 is provided at a position facing the head unit 1 across the paper transport path 6. The empty discharge recording liquid reservoir 7 only needs to have a necessary minimum opening area in the entire nozzle array region of the head unit 1, and holds the paper at a fixed interval (usually about 1 mm) from the paper feeding and ink discharge surfaces. It doesn't interfere with that. Further, an uneven surface 7 a is formed on the wall surface and the bottom surface of the empty ejection recording liquid reservoir 7.

An ink absorber 8 capable of absorbing ink is accommodated in the empty ejection recording liquid reservoir 7. The ink absorber 8 is formed of a porous body such as a urethane foam body.
In addition, the ink absorber 8 is provided throughout the empty ejection recording liquid reservoir 7, but may be provided partially (for example, a wall surface portion, a bottom surface portion, or the like) or may not be provided.

  Further, on the upstream side and the downstream side of the head unit 1, paper detection sensors 9 and 10 which are detection means for detecting the presence or absence of paper are arranged. The paper detection sensors 9 and 10 use optical sensors, but are not limited to this, and may be, for example, mechanically detecting the presence or absence of paper.

Next, an outline of the control unit of the ink jet recording apparatus will be described with reference to FIG.
This control unit includes a microcomputer (hereinafter referred to as “CPU”) 20 that controls the entire recording apparatus that also functions as the idle ejection operation control means according to the present invention, a ROM 21 that stores necessary fixed information, and A RAM 22 used as a working memory, a color processing circuit 23 that performs processing such as separating image data (image information) received from the host into necessary color data, and an image memory 24 that stores data obtained by processing the image data. A parallel input / output (PIO) port 25, an input buffer 26, a gate array (GA) or parallel input / output (PIO) port 27, a head drive circuit 28, a driver 29, and the like.

  Here, the image data (image information) received from the host side is stored in the input buffer 26, and the multi-valued color image data as the received data is processed by the color processing circuit 23 to perform γ correction, UCR processing, halftone processing. The binary color image data is generated by performing necessary processing such as the above, and is stored in the image memory 24 as the printing data, and the printing data for one line is read and the head driving circuit is connected via the PIO port 27. 28, the corresponding color heads 1k, 1c, 1m, and 1y of the head unit 1 are driven.

  In addition to the image information from the host side, the PIO port 25 includes data such as paper type data indicating the paper type, various instruction information from an operation panel (not shown), and the above-described paper detection sensor 9 that detects the presence or absence of paper. 10 and the like, and necessary information is sent to the host side and the operation panel side via the PIO port 25.

The head drive circuit 28 also generates energy generating elements (piezoelectric elements) corresponding to the nozzles of the head heads 1k, 1c, 1m, and 1y of the head unit 1 based on various data and signals given through the PIO port 27. A drive waveform is applied to an energy generation element of a drive nozzle (nozzle for ejecting ink droplets) in accordance with image information in an electromechanical conversion element such as an electrothermal conversion element or an electrothermal conversion element such as a heater.
Further, the driver 29 drives the paper feed motor 30 in accordance with drive data given through the PIO port 27 to convey a predetermined amount of paper.

The operation of the ink jet recording apparatus configured as described above will be described with reference to FIG.
First, referring to FIG. 4, when the paper detection sensor 9 detects the absence of paper and the paper detection sensor 10 detects the absence of paper, that is, the paper supply sensor When no paper is being carried out and the paper discharge operation has been completed, the heads 1k, 1c, 1m, and 1y of the head unit 1 are driven via the head drive circuit 28. Thus, an idle ejection operation for idly ejecting ink droplets from the nozzles is performed.

  Then, when the paper detection sensor 9 after ink droplet ejection by the idle ejection operation detects the presence of paper, the ink droplet ejection by the idle ejection operation is terminated, and until the paper detection sensor 9 detects the presence of paper, for example, in advance The operation of ejecting ink droplets is repeated a predetermined required number of times, or the operation of ejecting ink droplets at predetermined intervals is performed until the paper detection sensor 9 detects the presence of paper.

  That is, as shown in FIG. 5, when the paper P1 is fed and is in an area where printing by the head unit 1 is possible (this is referred to as “printing area”), the paper P1 is conveyed to the image data. In response, the heads 1k, 1c, 1m, and 1y of the head unit 1 are driven to eject ink droplets I to record an image.

  Then, as shown in FIG. 6, when recording on the paper P1 is completed and the paper P1 is removed from the printing area by the paper discharge operation, and the next paper P2 is not fed to the printing area, the head unit Each of the heads 1k, 1c, 1m, and 1y of 1 is driven to eject the idle ejection ink droplet I.

  In this way, the ink droplets I ejected from the heads 1k, 1c, 1m, and 1y of the head unit 1 by the idle ejection operation are directly ejected into the idle ejection recording liquid reservoir 7 below, and the ink absorber 8 Absorbed and retained.

  In this case, the idle ejection operation is performed after the sheet is discharged from the recording area until the next sheet is fed to the printing area, but the idle ejection operation itself takes about 0.1 to 3 seconds. Therefore, the printing speed is not substantially reduced by controlling the paper supply / discharge timing.

  As described above, since the idle ejection operation is performed until the recording-completed sheet is removed from the printing area and the next sheet is conveyed to the printing area, the printing speed is reduced. Therefore, the head can be recovered by the idle ejection operation.

  In addition, an empty discharge recording liquid reservoir that holds recording liquid discharged during the empty discharge operation is provided at a position opposed to the head across the paper transport path, so that the head can be mechanically moved and empty on the paper. The ejection of ejected ink droplets is eliminated, and the idle ejection operation can be performed without reducing the printing speed, so that the printing quality can be maintained high. Further, the paper conveyance path (guide plate or the like) is not soiled by idle driving due to an idle ejection operation or malfunction, and the paper is not soiled.

  In this case, it is possible to prevent rebound of the ejected recording droplets by providing a liquid absorber that absorbs and holds the recording liquid in the idle ejection recording liquid reservoir. Also, the head can prevent the waste recording liquid from leaking from the empty ejection recording liquid reservoir by disposing the recording liquid ejection surface downward. Furthermore, a color image can be printed with high quality by providing a plurality of heads of each color as the heads.

  In addition, a detection unit that detects that no sheet is interposed between the head and the empty discharge recording liquid reservoir, and a unit that causes the head to perform an empty discharge operation based on the detection result of the detection unit, Allows the ink droplets to be ejected with a good nozzle state for each sheet, improving the image quality and performing the idle ejection operation with the paper present. This prevents the paper from being stained.

Next, another embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the inside of the empty discharge recording liquid reservoir 7 is connected to the waste ink tank 32 via the tube 31, and the suction pump 33 for forcibly discharging the retained ink in the empty discharge recording liquid reservoir 7 to the waste ink tank 32. Is intervening.

  Then, as shown in FIG. 8, the control unit periodically operates the suction pump 33 to forcibly discharge the ink in the empty discharge recording liquid reservoir 7 to the waste ink tank 32. Here, the periodic forced discharge operation can be set, for example, when a certain time has elapsed or when the number of idle ejection operations reaches a predetermined number (example of this embodiment). As a result, it is possible to completely prevent the overflow of ink in the empty ejection recording liquid reservoir 7.

It is a principal part schematic explanatory drawing of the mechanism part of the inkjet recording device which concerns on this invention. It is a principal part schematic perspective view of the mechanism part. 2 is a schematic block diagram of a control unit of the recording apparatus. FIG. It is a flowchart with which it uses for description of the idle discharge operation processing of the control part. It is explanatory drawing at the time of the printing used for description of idle discharge operation | movement. It is explanatory drawing at the time of the idle discharge operation | movement similarly used for description of an idle discharge operation | movement. It is a principal part schematic explanatory drawing of the other mechanism part of the inkjet recording device which concerns on this invention. It is a flowchart with which it uses for description of the forced discharge process in the 7th embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Head unit 1y, 1m, 1c, 1k ... Head 3 ... Guide plate 4 ... Paper feed roller pair 5 ... Paper discharge roller pair 6 ... Paper conveyance path 7 ... Empty discharge recording liquid reservoir 8 ... Ink absorber 9, 10 ... Paper detection sensor

Claims (2)

  In a line-type ink jet recording apparatus provided with a head in which a plurality of nozzles that eject ink droplets are arranged over substantially the entire width of a recording area, the paper on which recording has been completed is out of the printing area, and the next paper is placed in the printing area. An ink jet recording apparatus that performs an idle ejection operation before being conveyed. 2. The ink jet recording apparatus according to claim 1, further comprising an empty discharge recording liquid reservoir that holds a recording liquid discharged at the time of the empty discharge operation at a position facing the head across the paper conveyance path. Recording device.

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