JP2006168013A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for complementing a recording dot assigned to a nonejective nozzle in an ink jet recorder. <P>SOLUTION: The ink jet recorder comprises two complement means of nonejection nozzle for multipass nonejection complement processing and adjacent nozzle complement processing, and performs complement processing of a detected nonejection nozzle immediately thus eliminating deterioration in print quality of recording. After rewriting master data, multipass nonejection complement processing is performed without fail so that the number of nozzles performing complement processing is dispersed by the number of passes thus reducing the load per nozzle. It is contributive to prolongation of lifetime of the head and stabilization of ink ejection thus enhancing the effect of complement processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording apparatus for recording an image on a recording paper, for example, an image recording apparatus such as a color printer.

2. Description of the Related Art Conventionally, an ink jet type image recording apparatus that performs image recording on recording paper by ejecting ink from nozzles serving as recording elements of a recording head has been known.
OA equipment such as personal computers, copiers, word processors, etc. are becoming more and more colored with higher functionality, and various color ink jet recording devices are provided as one of the image forming (recording) devices in these devices. Has been.

  A typical ink jet recording apparatus includes a carriage on which a recording head and an ink tank are mounted, a transport mechanism for transporting recording paper, and control means for controlling these operations. A recording head for ejecting ink droplets from a plurality of ejection openings is serially aligned in a direction (hereinafter also referred to as “main scanning direction”) perpendicular to the recording paper transport direction (hereinafter also referred to as “sub-scanning direction”). During this period, ink is ejected onto the recording paper, while the recording paper is intermittently conveyed by an amount equal to the recording width between the scans, and a plurality of scans and paper conveyances are performed to perform the previous image area. Record.

  When performing color recording, a plurality of recording heads are provided according to the colors of a plurality of types of ink, and a color image is formed by overlapping ink droplets ejected from these recording heads or landing in close proximity. Record.

  As described above, the demand for inkjet recording apparatuses is increasing in a wide range of industrial fields as a relatively simple and excellent recording means, and there is a demand for higher printing speeds and the provision of images with even higher quality. Therefore, the miniaturization of nozzles and the speeding up of ink ejection are being promoted.

  On the other hand, as an ink ejection method in the ink jet recording apparatus, a so-called bubble jet (registered trademark) method is realized in which ink droplets are ejected by heating the ink with a heater and boiling the film. Cause the nozzle to melt and clog the nozzle, the ink in the nozzle dries and adheres due to oxidation, and the thermal expansion of the foam becomes insufficient due to the disconnection of the heater specific to the Bubble Jet (registered trademark) system. In some cases, ink jetting or non-ejection may occur. If there is a nozzle that does not eject ink, when the recording head is driven in the main scanning direction with respect to the recording medium, streaky noise is generated in the recording medium along the main scanning direction, which significantly reduces the recording quality. It will be.

  This means that when the nozzles of the recording head described above are further miniaturized and the number of nozzles is increased, the probability of abnormal nozzles increases in proportion to the number of nozzles, and the printing speed is increased. When trying to do so, there was a situation where it was more difficult to obtain an image without defects.

  In addition, from the viewpoint of manufacturing a recording head, all the nozzles must be normal and defect-free. Therefore, if the number of nozzles provided in one recording head is increased, the probability of occurrence of defects during manufacturing is increased. It increased in proportion to the number of nozzles, resulting in a decrease in manufacturing yield and an increase in manufacturing cost.

  Even when a defect-free recording head is manufactured, if a failure occurs in one nozzle during use, ink ejection from the failed nozzle becomes unstable, resulting in a defect in the resulting image. The recording head becomes unusable and is subject to replacement. In addition, in a 4- to 8-color ink jet printing apparatus having 4 to 8 recording heads composed of thousands of nozzles, if an abnormal nozzle occurs, a defective printed matter will be produced each time. In each case, the entire apparatus has to be stopped to replace the recording head, and the apparatus is not in a stable operation stage.

As a method for solving such a problem, a method for detecting ejection failure of a recording element (Patent Document 1) and a method for performing printing using an adjacent recording element instead of a recording element that has caused ejection failure (Patent Document 1) Document 2), or a recording element such as a method of performing printing by using different recording elements of different scans to perform printing at a position where a recording element that has failed to perform printing by multi-pass printing should be originally recorded (Patent Document 3) A method has been proposed in which the discharge failure is compensated for and the deterioration of the print quality is suppressed.
JP-A-11-188853 JP 2001-315318 A JP 2000-2111167 A

  However, in the first method of complementing the ejection failure of the recording element, that is, the method of recording using the adjacent recording element, the recording element that should have been ejected is adjacent to the dot that should have been recorded. Since the printing elements are distributed to the recording elements, the ejection frequency of the adjacent recording elements is relatively increased, and as a result, there is a problem that only the life of some of the recording elements is shortened.

  In the second method, that is, the method of performing multi-pass printing, when the data for multi-pass printing is distributed using a mask, the contents of the mask are determined according to the information of the recording element that is an ejection failure. It takes time because it has to be changed, and in the method for detecting the ejection failure of the recording element immediately before performing the recording as described above, for the recording immediately after detecting the ejection failure, There is a problem that print data that complements the ejection failure cannot be prepared.

  The present invention has been made in view of such a problem, and after detecting a recording element having an ejection failure, a process for complementing it immediately is performed to suppress a decrease in recording quality, and a recording head. It is an object of the present invention to provide a recording apparatus that effectively uses the remaining recording elements and does not reduce the life of the recording elements.

  An ink jet recording apparatus according to the present invention is an ink jet recording apparatus that includes a recording head composed of a plurality of recording elements, and performs recording by discharging ink onto recording paper while reciprocally scanning the recording head. Scanning means for reciprocating scanning, test ejection means for performing test ejection of the recording head, provided outside the effective recording area where recording by the recording head on the scanning path of the recording head is performed, and by the test ejection means Non-ejection detection means for detecting ink ejection states from a plurality of recording elements of the recording head from the ink ejection made, and recording of the recording head for each scan in a plurality of scans of the recording head by the scanning means A control unit that sequentially selects elements and detects an ink discharge state by the non-ejection detection unit; And having a non-ejection supplementing means for reconstructing the recording data assigned to the faulty nozzle before the recording upon detection of a discharge failure of the ink recording element is made.

  The non-ejection complementing means includes an adjacent non-ejection complementing means for performing printing using recording elements adjacent to both sides in place of the defective ejection recording element when a defective ejection recording element is detected; It is characterized by comprising multi-pass non-ejection complementing means that performs printing of dots that should be printed by the recording element that has become defective by using different recording elements of different scans, and switching between the two complementing means.

  As described above, according to the present invention, there are two non-ejection nozzle complementing means for the multi-pass non-ejection complementing process and the adjacent nozzle complementing process. In the detection system, it is possible to immediately perform a complementing process on the detected non-ejection nozzles and perform recording without deteriorating the print quality. Further, after rewriting the mask data, the multi-pass non-ejection complementing process is always performed. Therefore, the nozzles that perform the complementing process are dispersed by the number of passes rather than recording by always using the adjacent nozzle complementing process. Since the load is reduced, the overall head life is also improved.

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

[Description of system configuration (FIGS. 1 to 3)]
Hereinafter, FIGS. 2 and 3 show a method of detecting non-ejection of ink.

  FIG. 2 is a perspective view showing a schematic configuration of mainly a recording unit of an ink jet recording apparatus provided with an ink non-ejection detection means.

  In the figure, reference numeral 201 denotes an ink cartridge, which individually stores black (Bk), cyan (C), magenta (M), and yellow (Y) inks. It is configured integrally.

  Reference numeral 202 denotes a print head cartridge, which is used in the form of one unit in which four print heads corresponding to the respective inks stored in the ink cartridge 201 are housed. That is, the recording head cartridge 202 accommodates four recording heads that eject inks of Bk, C, M, and Y, respectively.

  Reference numeral 203 denotes a carriage on which the ink cartridge 201 and the head cartridge 202 containing the recording head are detachably mounted. The carriage 203 can move along the guide shaft 210 by being slidably engaged with a guide shaft 210 described later. Furthermore, the carriage 203 is provided with an encoder sensor and faces an encoder scale 204 described later.

(Not shown)
Reference numeral 204 denotes an encoder scale provided on a surface facing the carriage 203, and slits are provided at predetermined intervals. The encoder sensor irradiates the emitted light to the encoder scale 204 and outputs a signal related to the scanning position of the carriage 203 based on the reflected light.

  The encoder sensor 102 and the encoder scale 204 provided on the carriage 203 constitute an encoder unit 102 described later.

  Reference numeral 205 denotes a paper feed roller. The recording paper 209 can be conveyed in the y direction in the figure by rotating in the direction of the arrow in the figure while sandwiching the recording paper 209 together with the auxiliary roller 206.

  Reference numerals 207 and 208 denote a pair of paper feed rollers, which feed the paper while holding the recording paper 209 therebetween.

  A cap 211 is provided at the end of the scanning path of the carriage and also functions as an ink receiver. The cap 211 moves up and down as necessary. When the cap 211 is raised, the cap 211 is in close contact with the recording head and covers the nozzle portion to prevent ink evaporation and dust adhesion.

  A nozzle non-ejection detection unit 212 includes an ink receiving member 301, a light emitting element 302, and a light receiving element 303, which will be described later, and is provided between the end of the recording paper conveyance path and the cap 211.

  A recording head that ejects ink includes a plurality of nozzles that are recording elements arranged in series on the lower surface thereof, and ejects ink while reciprocating in the main scanning direction (x direction in FIG. 2).

  Then, on the ink receiving member 301 disposed at a predetermined position on the outside of the recording paper 209, ink droplets are sequentially ejected from the main scanning recording head. At the same time, a light beam is output from the light emitting element 302 so as to cross the lower surface of the recording head obliquely with respect to the main scanning direction to irradiate the ink droplet, and the light beam blocked by the ink droplet is received by the light receiving element 303. That is, while performing main scanning, the ink droplets ejected from each nozzle of the recording head are ejected sequentially from each nozzle at the timing when the ink beam just passes through the light beam. By doing so, it is possible to detect whether or not ink droplets are ejected from the recording head based on the timing of ejecting ink droplets and the output of the light receiving element 303. That is, if the passage of the ink droplet is detected by the optical sensor a predetermined time after the ink droplet is ejected, it can be determined that the ink is ejected normally from the nozzle, and the progress of the ink droplet cannot be detected. For example, it can be determined that the nozzle is a non-ejection nozzle.

  FIG. 3 is a diagram schematically showing an operation of detecting the ink discharge state during forward scanning by moving the carriage 203 in the direction of the arrow.

  In the figure, reference numeral 301 denotes a member that receives ink droplets ejected in order to detect non-ejection of ink.

  Reference numeral 302 denotes a light emitting element, which uses an infrared LED, and has a lens integrally formed on the LED light emitting surface, and can project a beam light approximately in parallel toward the light receiving element 82. Reference numeral 303 denotes a light receiving element, for which a phototransistor is used.

  An optical axis 304 that connects the light emitting element 302 and the light receiving element 303 is disposed so as to intersect the nozzle array of the recording head 305 at an angle θ, and the distance between the light emitting element 302 and the light receiving element 303 is the head length of the recording head 305. It is wider than (L). When the ink droplet passes through the detection range, the ink droplet blocks light from the light emitting side, reduces the amount of light to the light receiving side, and a change in the output of the phototransistor that is the light receiving element 303 is obtained.

  The nozzles that are black circles are the ejection positions on the ink receiving member 301 of the fourth nozzle, the eighth nozzle, the twelfth nozzle, and the sixteenth nozzle, respectively. L is the head length (effective recording length: actually the distance from the first nozzle to the last nozzle of the recording head), X is the head-to-head distance between adjacent nozzle rows, LP is the pitch between adjacent nozzles, and XP is the carriage This is the adjacent recording dot pitch in the moving direction.

  In this embodiment, the adjacent recording dot pitch (XP) matches the recording resolution of the printer. When the recording head 305 moves in the direction of the arrow, first, ink is ejected from the fourth nozzle at position A. At that time, the ejection position of the ink droplet ejected from the fourth nozzle is controlled so as to cross the optical axis 304 of the beam light. Further, the recording head 305 moves in the direction of the arrow, and then ink is ejected from the eighth nozzle at position B. At that time, the ejection position of the ink droplets ejected from the eighth nozzle is controlled so as to cross the optical axis 304 of the beam light as in the case of the fourth nozzle. Hereinafter, similarly, when the recording head 305 moves in the direction of the arrow, ink is sequentially ejected from the 12th and 16th nozzles at positions C and D.

  In this way, ink is ejected from the four nozzles in accordance with the movement of the recording head 305, and information regarding each ejection state is obtained from the output of the light receiving element 303. When the recording head 305 further moves in the direction of the arrow and the position reaches the position E, the same ink ejection operation is performed on the adjacent nozzle rows. When forward scanning is performed in this way, the ink ejection state from the nozzles is detected while moving the recording head 305 in the direction of the arrow.

  Here, the reason why the discharge nozzle interval (Y) in the detection of the ink discharge state is set to three nozzles is that the moving speed of the carriage 203 is limited.

  In this case, when recording on an actual recording medium, the moving speed of the carriage 203 is V [mm / s], and the ink droplet ejection period from the recording head 305 is T [μsec]. Since the ink discharge state is detected without changing the above, the condition of the nozzle interval is necessary.

  Assuming that the total number of nozzles in the nozzle array of the recording head is N, the discharge nozzle interval (Y), the angle (θ) between the nozzle array and the beam light, and the effective recording length (L) are generally expressed by the following equations (1), ( 2) and (3).

Y = INT {[N ÷ INT (X ÷ (V × T))] + 1} (1)
θ = 1 / Y ≦ (X−XP) / L (2)
L = (N−1) P (3)
The example shown in FIG. 3 is a case where the discharge nozzle interval (Y) is Y = 3. At this time, when the recording head 305 crosses the optical axis 304 four times, the ink discharge state for all 16 nozzles can be detected by executing the ink discharge operation.

  FIG. 1 is a block diagram showing an electrical configuration in the present embodiment.

  In the figure, reference numeral 102 denotes an encoder, which includes an encoder sensor and an encoder scale 204. The position of the carriage 203 can be detected by a signal output from the encoder 102.

  Reference numeral 103 denotes a timing signal output circuit. After shaping and receiving the position information signal of the carriage 203 output from the encoder 102, each block operates on a non-discharge detection controller 104 and a discharge controller 107, which will be described later. A timing signal for output is output.

  Reference numeral 104 denotes a non-ejection detection controller. When it is detected that the carriage has come on the non-ejection detection unit 212 according to the timing signal output from the timing signal output circuit 103, the non-ejection detection unit 212 is driven and the light emitting element 302 is driven. It prepares to irradiate an ink drop by outputting a light beam more. Further, after detecting non-ejection, when receiving an output from the non-ejection detection unit, it outputs to the non-ejection complementing circuit 105 whether or not the nozzle to be detected ejected ink.

  Reference numeral 105 denotes a non-ejection complement circuit, which performs non-ejection complement processing using adjacent nozzles. Based on the non-ejection information of the nozzles output from the non-ejection detection controller 104, correction is applied to the print data output from the SDRAM 107 described later. After the correction, the print data is output to the discharge controller 106 described later.

  An ejection controller 106 receives a timing signal output from the timing signal output circuit 103 and outputs a print data output request signal to an SDRAM 107 described later. Also, the corrected print data output from the non-ejection complement circuit 105 is received and output to the recording head for printing.

  Reference numeral 107 denotes an SDRAM which stores print data sent from a host computer (not shown) and subjected to HV conversion, and mask data for performing multi-pass printing.

  In response to an output request from the discharge controller 106, the print data output from the SDRAM 107 is first output to the non-discharge complement circuit 105, and is corrected based on the non-discharge information of the nozzles. After that, it is input to the discharge controller 106.

  A CPU 101 is connected to the timing signal output circuit 103, the non-ejection detection controller 104, the non-ejection complement circuit 105, the ejection controller 106, and the SDRAM 107 via the CPU bus. The CPU 101 sets a register relating to each print control for each block except the SDRAM 107, and sets mask data for the SDRAM 107 and rewrites the mask data when performing multi-pass non-ejection complement processing. Do.

  Hereinafter, FIGS. 4, 5 and 6 show a method for complementing the detected non-ejection of ink.

  FIG. 4 is a diagram illustrating a method of adjacent nozzle complement processing using a nozzle adjacent to a non-ejection nozzle. In the same figure, instead of dots that could not be printed due to nozzle non-ejection, the recording data that the non-ejection nozzle was supposed to strike was reconstructed, and the upper and lower dots were printed by nozzles adjacent to the non-ejection nozzle. Completion processing is performed by doing. In other words, before the recording is performed, the discharge signal assigned to the nozzle that has been determined to be non-discharge is changed by the non-discharge complementing means so that the adjacent nozzle discharges. Since it is not desirable from the viewpoint of the life of the nozzle that the discharge concentrates on one nozzle, when performing the complementary processing, the upper and lower nozzles of the non-discharge nozzle are alternately discharged. Further, if the dots above and below the dot that cannot be printed are already printed dots, no processing is performed.

  FIG. 5 and FIG. 6 are diagrams showing a method of multi-pass interpolation processing for performing non-ejection nozzle complement processing during multi-pass printing. In these drawings, 4 × 4 masks are used to represent 4 This shows a method of completing the printing of the print area of the head length L (see FIG. 3) by one scanning, that is, a 4-pass printing method.

  FIG. 5 is a diagram showing a processing method when there is no non-ejecting nozzle. The 4 × 4 mask pattern used here has a print data transmission ratio of 25% and is a complementary mask pattern. Is used.

  FIG. 6 shows a processing method when a non-ejection nozzle is detected when processing is performed by the method of FIG. Since a non-ejection nozzle is detected among the nozzles used in pass 1, the mask at the place where printing should have been originally performed using the nozzle is changed from transmission to non-transmission. Then, the same part of pass 2 is changed from non-transparent to transparent. As a result, the dots that should have been printed in pass 1 are printed in pass 2.

  By using multi-pass printing in this way, it is possible to record dots at locations where the nozzles that could not be recorded due to ejection failure should originally be recorded using different ejectable nozzles.

  In the above example, the non-transparent portion of pass 2 is changed to the transparent portion, but this operation may be performed on pass 3 or pass 4.

  FIG. 7 is a flowchart showing the processing procedure of the ink jet recording apparatus in the present embodiment.

  First, in S1, recording of one job is started.

  Next, in S2, it is determined whether or not one job has been recorded.

  If the job recording has not been completed in S2, the process proceeds to S3.

  In S3, main scanning of the carriage 203 is started.

  In S4, nozzle non-ejection detection processing is performed when the carriage 203 passes over the non-ejection detection unit 212 before reaching the recording area. Then, the process proceeds to S5.

  In S5, it is determined whether or not there is a non-ejection nozzle as a result of the nozzle non-ejection detection process performed in S4.

  If a non-ejection nozzle is detected in S5, the process proceeds to S6.

  In S6, rewriting of mask data via the CPU is started based on the location where the non-ejection nozzle is detected (see FIGS. 5 and 6).

  When rewriting of the mask data is started in S6, the process proceeds to S7.

  In S7, since rewriting of the mask data has not been completed for the non-ejection nozzle detected in S5, the adjacent nozzle complementing process is performed and the process proceeds to S11.

  In S11, one main scanning has been completed, and the process returns to S2 to determine again whether or not the recording is completed.

  On the other hand, if no non-ejection nozzle is detected in S5, the process proceeds to S8.

  In S8, it is determined whether or not a non-ejection nozzle is detected in the non-ejection nozzle detection performed before the non-ejection nozzle detection performed in S5.

  In S8, if there is no previously detected non-ejection nozzle, the normal recording is performed and then the process returns to S2 to determine again whether or not the recording is finished.

  On the other hand, if there is a previously detected non-ejection nozzle in S8, the process proceeds to S9.

  In S9, it is determined whether or not rewriting of mask data for the multi-pass non-ejection complementing process performed for the non-ejection nozzles detected before the non-ejection nozzle detection performed in S5 is completed.

  If the rewriting of the mask data has not been completed in S9, the process proceeds to S7, and the adjacent nozzle complement process is performed for the target nozzle to perform recording. After that, the process proceeds to S11 as before, and then returns to S2 to determine whether or not the recording is completed.

  On the other hand, if the rewriting of the mask data has been completed in S9, the process proceeds to S10.

  In S10, recording is performed using the rewritten mask data, and the process proceeds to S11. Thereafter, the process returns to S2 to determine whether the recording is finished.

  If it is determined in S2 that the printing has been completed, the process is terminated while maintaining the non-ejection information of the nozzles up to that point.

  In the above embodiment, when nozzle non-ejection is found, rewriting of mask data for multi-pass non-ejection supplement processing is started immediately, and adjacent nozzle complement processing is completed until rewriting of mask data is completed. After rewriting the mask data, the main scan immediately after that is recorded using the multi-pass non-ejection complement processing, but the timing of switching from this adjacent nozzle complement processing to the multi-pass non-ejection complement processing is For example, it may be after one page is finished or after one job is finished.

  In the above embodiment, the adjacent nozzle complement processing is performed by hardware, but this may be realized by processing by software.

It is a block diagram which shows the electrical structure in the 1st Embodiment of this invention. FIG. 2 is a perspective view illustrating a schematic configuration mainly of a recording unit of an ink jet recording apparatus including an ink non-ejection detection unit. FIG. 5 is a diagram schematically showing an operation of detecting an ink discharge state during forward scanning by moving a carriage in the direction of an arrow. It is a figure which shows the method of the adjacent nozzle complementation process using the nozzle adjacent to a non-ejection nozzle. It is a figure which shows the method of the multipass complement process which performs the complement process of a non-ejection nozzle in performing multipass printing, and is the figure which showed the processing method when there is no non-ejection nozzle. FIG. 6 is a diagram showing a method of multi-pass complement processing for performing non-ejection nozzle supplement processing during multi-pass printing, and when non-ejection nozzles are detected during processing by the method of FIG. The processing method is shown. 3 is a flowchart illustrating a processing procedure of the ink jet recording apparatus according to the first embodiment of the present invention.

Explanation of symbols

101 CPU
DESCRIPTION OF SYMBOLS 102 Encoder 103 Timing signal output circuit 104 Non-ejection detection controller 105 Non-ejection complement circuit 106 Ejection controller 107 SDRAM
DESCRIPTION OF SYMBOLS 201 Ink cartridge 202 Printhead cartridge 203 Carriage 204 Encoder scale 205 Paper feed roller 206 Auxiliary roller 207 Paper feed roller 208 Paper feed roller 209 Recording paper 210 Guide shaft 211 Cap 212 Nozzle ejection unit 301 Ink receiving member 302 Light emitting element 303 Light receiving element 304 Optical axis 305 Recording head

Claims (2)

  An ink jet recording apparatus comprising a recording head comprising a plurality of recording elements and performing recording by ejecting ink onto recording paper while reciprocatingly scanning the recording head, the scanning means for reciprocally scanning the recording head, and the recording A test ejection unit that performs a test ejection of the head; and an effective recording area that is recorded by the recording head on a scanning path of the recording head. Non-ejection detection means for detecting ink ejection states from a plurality of recording elements, and a plurality of scans of the recording head by the scanning means, the recording elements of the recording head are sequentially selected for each scan, and the non-ejection is performed. Control means for detecting the ink ejection state by the detection means, and when non-ejection of the ink of the recording element is detected by the detection means An ink jet recording apparatus characterized by having a non-ejection supplementing means for reconstructing the recording data assigned to the faulty nozzle before the recording is made.   The non-ejection complementing means includes an adjacent non-ejection complementing means for performing printing using recording elements adjacent to both sides instead of the ejection defective recording element when a defective ejection recording element is detected; 2. The multi-pass non-ejection complementing means that performs printing of dots that should be printed by different printing elements by different printing elements of different scans, and switches between two complementing means. The ink jet recording apparatus described.

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