JP2007320288A - Control method of undischarge nozzle of ink-jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the life of a head by distinguishing whether the cause of undischarge is failure of a heater or clogging of nozzles and differentiating the treatment for the undischarge nozzles. <P>SOLUTION: Among undischarged nozzles, the nozzles having heaters which are not in failure are identified as clogged nozzles. The clogged nozzles are considered to be capable of recovering from the undischarge state, and a recover treatment is performed. Since it is clear that the nozzles having malfunctioning heaters do not discharge, they are masked so that no more application is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inkjet printing apparatus that forms an image using a print head in the form of an inkjet head that ejects ink onto a print medium such as paper, and a non-ejection nozzle control method for the print head for the apparatus. .

  Some conventional ink jet printing apparatuses have means for detecting non-ejection of ink from ejection openings provided in a print head. Such an ink jet printing apparatus is configured to be able to be used for a print head failure determination process by displaying or storing information on nozzles that have fallen into a non-ejection state based on the result of the non-ejection detection operation.

  Inkjet printing devices may cause non-ejection due to poor filling of ink in the liquid path, or non-ejection due to increased viscosity of ink near the ejection port or adhesion of dust. In order to remove the cause of ejection and maintain good ejection performance, it is common to provide recovery processing means for forcibly ejecting ink from the ink ejection ports.

  Further, in the print head when ink is ejected, the heater that generates bubbles is damaged by the pressure at the time of defoaming and the heat of the heater surface, and the protective film on the heater surface is gradually scraped. After the heater covered with the protective film is exposed, the wiring portion is eroded and the wiring resistance is deformed. At this time, ejection failure or non-ejection occurs by applying a voltage to the heater that has an abnormal resistance value due to deformation of the wiring resistance. In addition, applying a voltage to the heater causing the abnormal resistance value adversely affects the surrounding protective film, and a continuous resistance value abnormality of the heater may occur.

  Some conventional inkjet heads detect clogged nozzles, perform non-discharge complementation with adjacent nozzles, and if there are a large number, instruct users to perform maintenance (see, for example, Patent Document 1).

  In addition, there is a type in which a discharge abnormality of a droplet discharge head is detected, and the cause is divided into paper powder adhesion magnitude, ink dry thickening magnitude, and bubble mixing, and recovery processing is performed according to those causes ( For example, see Patent Document 2.)

In addition, there is a technique in which a resistance value of a heat generating element is measured to identify a heat generating element in a disconnected state, and the energy applied to the disconnected heat generating element is applied to the proximity heat generating element (see, for example, Patent Document 3).
JP 2005-238682 A JP 2004-314457 A JP 2005-271435 A

  However, since the conventional technology does not distinguish the cause of non-ejection from heater failure or nozzle clogging, the processing to the non-ejection nozzle is made the same and the life of the head is shortened. There was still an insufficient problem in practical use.

  In order to solve such a problem, in the present invention, nozzles in which the heater is not broken out of non-ejection nozzles are identified as clogged nozzles. The clogging nozzle is assumed to be able to recover from the non-ejection state, and recovery processing is performed. Further, since it is clear that a nozzle having a malfunctioning heater does not discharge, a mask is applied so as not to apply the nozzle again.

  By applying the recovery process to only the clogged nozzles by dividing the cause of the non-ejection nozzle into clogged or a heater failure, it is possible to avoid application to the failed nozzle. As a result, it is possible to prevent a continuous resistance value abnormality of the heater and to extend the life of the head.

  Further, when the nozzle detected as non-ejection is only a defective nozzle, there is no need to perform a recovery process. Therefore, when the recovery process for forcibly discharging the ink from the ink discharge port is used, it is possible to prevent the ink from being wasted. In addition, since the failed nozzle cannot be recovered, the process of wiping the ink ejection surface of the head and the capping process for covering the ink ejection surface of the head can be saved, and efficient recovery processing can be performed. It is.

  (Overall Configuration) FIG. 1 shows a configuration example of a main part of an ink jet printing apparatus including a mechanism for detecting non-ejection. The detection of non-ejection is to detect the ejection state of whether or not the ink is ejected normally, and hereinafter simply referred to as “ejection detection”, “non-ejection detection”, or “ejection state detection”. Will be described.

  The print head 110 performs a printing operation when moving (main scanning) in the direction of arrow 2 (forward direction) indicated by a solid line, and also performs a printing operation when moving in the direction of arrow 3 (reverse direction) indicated by a broken line. Do. For example, the print head 110 may be configured to eject ink using thermal energy. That is, a heater that generates thermal energy in response to energization is provided corresponding to the discharge port, and film boiling occurs in the ink by the thermal energy applied by the heater, and the pressure of bubbles generated at that time is utilized. In addition, printing can be performed by discharging ink from the discharge port.

A broken line denoted by reference numeral 121 is a light beam that is narrowly narrowed and output from the light emitting unit 120. Ink droplets 111 and 112 to 11n are ejected from the ejection port during the main scanning movement of the head 110 so as to block the optical axis of the beam. I will do it. The light beam 121 is received by the light receiving unit 130 and the light intensity is detected. Reference numeral 140 denotes a member that receives ink ejected for ink droplet detection during the processing. Reference numeral 180 denotes a print medium such as paper or cloth, which is intermittently sub-scanned (paper fed) in the direction of the arrow 4. Assume that hatched portion 181 has already been printed, and non-hatched portion 182 indicates that it will be printed. In order to detect the position of the head in the main scanning, a scale of the linear encoder 170 fixed to the apparatus main body is read by a position reading unit 160 attached to a carriage (not shown) on which the head is placed. It can be carried out. The encoder 170 serves as a reference when performing an image printing operation, and is disposed for the purpose of realizing ideal landing of ink on the print medium 180 and improving image quality.

  Reference numeral 150 denotes a recovery processing unit, which is a cap member that caps the discharge port forming surface of the print head, a suction means such as a pump that forcibly discharges ink from the discharge port by sucking the inside of the cap, and a discharge port forming surface It is comprised from the member etc. which perform wiping.

  In the figure, only one print head is shown for discharging ink of one color (black (BK)), but other colors such as cyan (C), magenta (M) and yellow (Y) are also shown. A plurality of print heads may be provided correspondingly. In addition to providing a print head for each color as described above, a configuration in which a nozzle group for ejecting BK ink and a nozzle group for ejecting Y, M, and C inks are arranged in one print head may be used. A print head having a nozzle group for ejecting BK ink and a print head having a nozzle group for ejecting Y, M, and C inks may be juxtaposed independently.

  Further, the print head may be integrated with an ink tank that forms an ink supply source, or may receive ink supply from an ink tank provided in another part of the apparatus via a tube or the like. Further, when the print head and the ink tank are integrated, the cartridge may be configured to be detachable from the apparatus main body (carriage), and both can be separated so that, for example, only the ink tank can be replaced independently. You may have done.

(Resistance abnormality detection circuit)
FIG. 2 is a diagram illustrating an internal mechanism of the print head unit 110 in the ink jet recording apparatus according to the embodiment.

  In FIG. 2, reference numerals 220 to 21n denote heater resistors for generating bubbles, and reference numerals 221 to 22n denote switch transistor portions that control energization of the heater resistance. Electric signals developed for printing from a1 to an are input to the switch transistor portion. One end of the heater resistor is commonly connected to the head voltage VH, and the other end is connected to a switching transistor and is connected to GND.

  An output signal is extracted from between each heater resistor and the VH signal, and the output digital signal is input to the selector 240 via analog-digital converters (AD converters) 231 to 23n. The selector is controlled by a control signal ax, and this control signal is linked with the ON signal of the electric signals a1 to an, and always selects the output of the AD converter corresponding to the ON signal of the electric signals a1 to an. It is configured to The electrical signals a1 to an and the control signal ax are input from the output of a so-called logic circuit or directly from the CPU. An output signal of the selector 240 is connected to an external port of a CPU described later through a print head control circuit described later.

  When the a1 signal is turned ON, a current from VH flows into GND through the heater resistance and the switching transistor portion. As a result, a voltage approximately proportional to the heater resistance is generated at the upper end of the heater resistor 211. This value is AD-converted by the AD converter 231, selected by the selector 240, and read by the CPU as an output signal.

  The read value is compared with a standard value that the heater resistance can normally take. If the resistance is significantly far from the standard value, or is extremely small, on the contrary, it is determined that the heater resistance by the a1 switch is abnormal, and the heater resistance 211 is stored as NG in the storage device EEPROM 314 shown in FIG. On the other hand, if the heater resistance 211 is within a certain range with respect to the standard value, it is determined that there is no abnormality in the heater resistance by the a1 switch.

(Device control system configuration)
FIG. 3 is a configuration example of a control system of the ink jet printing apparatus shown in FIG. In the figure, reference numeral 301 denotes a print head control circuit for electrically controlling the print head 110 and discharging ink in accordance with image data. Reference numeral 302 denotes an ejection detection sensor that detects an ink ejection state, and includes a light emitting unit 120 and a light receiving unit 130. A discharge detection control device 303 replaces the signal from the discharge detection sensor 302 with a discharge state signal for each nozzle.

  305 is a main scanning motor that is a driving source for scanning the print head 110 in the directions of arrows 2 and 3 shown in FIG. 1, 306 is a sub-scanning motor that is a driving source for transporting the print medium 180, and 307 is This is a recovery operation motor that serves as a drive source for operating the recovery processing unit 150. Reference numeral 309 denotes a recovery operation actuator that drives the recovery processing unit 150, and 310 denotes a recovery operation sensor for detecting an operation state of the recovery processing unit 150. A mechanism control circuit 311 controls and manages these various motors, actuators, and sensors.

  Reference numeral 304 denotes a CPU that controls the overall operation of each unit in accordance with a processing procedure to be described later. Reference numeral 313 denotes a RAM having an area for temporarily storing parameters in the course of execution of the processing procedure by the CPU 304, and reference numeral 314 denotes a nonvolatile memory such as an EEPROM for storing the ejection detection state even when the apparatus power is turned off.

  Reference numeral 315 denotes an operation / display unit, which includes a switch for the user to perform a required operation such as power-on and online / offline setting with the host device H, and a display for presenting the device status to the user. Have. The host device H serves as a supply source of image data to the inkjet printing apparatus, and is a computer that creates and processes data such as images related to printing, a reader unit for image reading, or A digital camera or the like may be used. Image data, other commands, status signals, and the like are transmitted / received via an interface (I / F) 316.

  In the above configuration, the operation in this embodiment will be described with reference to the flowchart of FIG.

  It is verified whether the nozzle is recorded in the EEPROM 314 as a failed nozzle during the recovery operation (step S401). If there is a record of the failed nozzle, the process proceeds to the next nozzle collation (step S407).

  If the EEPROM 314 does not record a failed nozzle, the ejection state of the nozzle is detected by the non-ejection detection circuit (step S402). If it is normal ejection (step S406), the process proceeds to the next nozzle collation. On the other hand, when the ejection failure of the nozzle is detected, it is detected by the resistance abnormality detection circuit whether the nozzle has failed (step S403).

  If the nozzle is identified as a failed nozzle, the nozzle number is stored in the EEPROM 314. This nozzle number information is stored in the EEPROM 314 as non-recoverable non-ejection nozzle information until the head is replaced (step S404). A non-application mask pattern for preventing the heater from being driven is generated based on the nozzle number information and clogging nozzle information described later.

  If it is not identified as a failed nozzle in step S403, it is identified as a clogged nozzle, and the nozzle number is stored in the EEPROM 314 (step S406). Here, the clogged nozzle information stored is used in a recovery process to be performed later.

  The nozzles are sequentially analyzed in such a procedure, and repeated until the analysis of all the nozzles is completed (step S407).

After performing the above procedure, the clogged nozzle information is read from the EEPROM 314 and the recovery process is performed. The recovery process here refers to a process for forcibly discharging ink from the ink discharge port, a process for sucking ink from the ink nozzle, a process for wiping the ink discharge surface of the head, and a cover for the ink discharge surface of the head. There is a possibility that the discharge state of the nozzle identified as the clogged nozzle is recovered by performing the recovery process that is the capping process. Therefore, the clogged nozzle number is read again from the EEPROM 314, and the non-ejection detection process is sequentially performed. If the ejection state recovers and normal ejection is confirmed here, the nozzle number is deleted from the EEPROM 314. If normal ejection cannot be confirmed, it is recorded in the EEPROM 314 as a clogged nozzle.

  The non-ejection nozzle information composed of the failed nozzle information and the clogged nozzle information stored in the EEPROM 314 can be reflected in the following processing.

  Print head replacement by the user by appropriately displaying information such as non-ejection nozzle information corresponding to the nozzle position and displaying it on the display of the operation / display unit 315 of the printing apparatus or the display device on the host device side It can be used to determine whether it is necessary. Further, in order to facilitate the necessity determination, a test pattern for confirming how much image quality degradation occurs may be formed by the print head.

  Further, based on the non-ejection nozzle information, a process of performing complementary printing by substituting the non-ejection nozzle with another normal ejection nozzle may be performed. Here, in an apparatus that performs multi-pass printing, the number of passes may be changed as appropriate so that the normal ejection nozzles face each other. Such complementary print processing may be automatically performed by the apparatus under the control of the CPU 304 based on non-ejection nozzle information, or may be determined by the user, or the switch or host device side of the operation / display unit 315 It may be implemented after setting using the input device.

1 is a schematic perspective view illustrating a configuration example of a main part of an inkjet printing apparatus including a mechanism for detecting non-ejection according to an embodiment of the present invention. FIG. 3 is a configuration diagram of a print head including a mechanism for detecting an abnormal resistance value according to an embodiment of the present invention. It is a block diagram which shows the structural example of the control system of the inkjet printing apparatus shown in FIG. It is a flowchart which shows the non-ejection nozzle control method in one Embodiment of this invention.

Explanation of symbols

110 Print Head 111, 112, 113 Ink Suitability 120 Issuing Unit 121 Light Beam 130 Participating Unit 140 Recovery Processing Unit 180 Print Medium

Claims (2)

  Causes of non-ejection nozzles in an inkjet recording apparatus that uses a print head that has a plurality of ejection openings and ejects ink from the plurality of ejection openings to a recording medium and performs recording An ink jet recording apparatus comprising: determining means for determining whether the ink is clogged or a heater has failed.   The determination means measures the resistance value of the resistance component of the print head unit, and the discharge detection means for detecting whether or not the ink is normally discharged for each of the plurality of discharge ports. The inkjet recording apparatus according to claim 1, wherein the determination is made based on a resistance abnormality detection unit that detects abnormality of the resistance component.

Images