JP2007021910A - Liquid delivery apparatus and method for discharging liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly detect poor discharge with a simple composition without wasting a recording member and discharged liquid. <P>SOLUTION: A differential image is acquired by the way of photographing a recording head with a CCD camera from the face side (step 102), processing an image and deducting a normal image from a photographed image (step 103). It is judged whether nozzles in the recording head are poor discharging nozzles or not by detecting a bubble in a passage, and the state of the inside of the passage and the inside surface based on the differential image (step 104). Based on the judged result, a retrieval operation, a discharging operation and other measures against non-discharging are properly performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus and a liquid ejection method for ejecting liquid from a recording unit such as an ejection head to a medium such as a recording medium.

  Recording devices having functions such as printers, copiers, facsimiles, etc., or recording devices used as output devices such as composite electronic devices and workstations including computers and word processors, are based on recorded information. An image (including characters and symbols) is recorded on a recording member (recording medium) such as an OHP (Over Head Projector) sheet. The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type, and the like according to a recording method.

  In a serial type recording apparatus that performs recording while performing main scanning in a direction crossing the transport direction (paper feeding direction, sub-scanning direction) of a recording member, recording means (on a carriage that moves along the recording member) An image is recorded (main scanning) by the recording head), and after recording for one line is finished, a predetermined amount of paper is fed (pitch conveyance as sub-scanning), and then the recording member stopped again is next. Recording of the entire recording member is performed by repeating the operation of recording (main scanning) the image of the first row. On the other hand, in a line type recording apparatus that records only by sub-scanning in the conveyance direction of the recording member, the recording member is set at a predetermined recording position, and after recording for one line at a time, a predetermined amount The entire recording member is recorded by repeating the operation of performing the paper feeding (pitch feeding) and recording the next line all at once.

  Among them, an ink jet recording apparatus (ink jet recording apparatus) performs recording by ejecting ink from a recording means (recording head) to a recording member. The recording means can be easily made compact and has high definition. Images can be recorded at high speed, can be recorded on special paper without requiring special processing, running cost is low, non-impact method is low noise, and many types of ink (for example, For example, it is easy to record a color image using a color ink. In particular, a line-type recording apparatus using a line-type recording unit in which a large number of ejection openings are arranged in the paper width direction can further increase the recording speed.

  As an energy generating element that generates energy used for discharging ink from the discharge port of an ink jet recording head, an element that uses an electromechanical transducer such as a piezo element, or an electromagnetic wave such as a laser is irradiated to generate heat. There are those that eject ink droplets by a heat generating action, and those that heat a liquid by an electrothermal converter having a heating resistor. Among them, an ink jet recording means (recording head) that discharges ink as droplets using thermal energy can perform high-resolution recording because the discharge ports can be arranged at high density.

  In particular, an ink jet recording means (recording head) that discharges ink using thermal energy is subjected to a semiconductor manufacturing process such as etching, vapor deposition, sputtering, and the like, an electrothermal transducer, an electrode, By forming the liquid channel wall, the top plate, etc., it is possible to easily manufacture a device having a high density liquid channel arrangement (discharge port arrangement), and to achieve further compactness. In addition, by utilizing the advantages of IC technology and micro processing technology, it is easy to make the recording means longer and planarized (two-dimensional), and it is also easy to make the recording means full-multiple and high-density mounting. is there.

  In addition, there are various requirements for the material of the recording member, and in recent years, development for these requirements has progressed, and paper (including thin paper and processed paper) that is a normal recording member and thin resin plate (OHP, etc.) In addition to the above, a recording apparatus using cloth, leather, non-woven fabric, metal or the like as a recording member is also used.

  A serial type ink jet recording apparatus generally has a recording means (recording head) for recording, a carriage mounted with the recording means and moving (main scanning), a driving system thereof, and a member for holding and transporting a recording member. A platen and a conveyance (paper feed) system; and an ejection recovery processing system for maintaining and recovering the ink ejection performance of the recording unit.

  In such an ink jet recording apparatus, when ink droplets are ejected from each ejection port in a recording operation or the like, in addition to main droplets flying to a recording member, ink composed of fine ink droplets that are generated secondaryly Mist may be generated. Then, the ink that has not reached the recording member, such as the ink mist, floats and adheres to the discharge port surface of the recording means, and this adhering ink is bonded and grown to cause “wetting” on the discharge port surface. “Wet” may enter from the inside of the discharge port, and inks of different colors may be mixed and mixed in the discharge port, thereby degrading the recorded image quality. In addition, color mixing can occur after suction recovery performed to maintain the ejection performance.

  In addition, while the recording is continued, an ink dropping phenomenon may occur in which the ink is not supplied into the ejection port due to a temperature rise of the recording head or the like. When ink drops occur, ink cannot be ejected from the ejection port, so white streaks occur in the image and image quality is degraded. In order to avoid this problem, recovery operation is performed by monitoring the print head temperature, environmental temperature, number of print dots, etc., and predicting the wet state of the discharge port surface by ink droplets and the state of the discharge port and common liquid chamber. Many inventions have been made to carry out.

  However, these inventions do not directly monitor the surface of the discharge port and the ink drop of the discharge port, and the wetting and the ink drop itself are easily influenced by the contamination of the discharge port surface and the discharge stability of the discharge port. Accurate prediction is difficult. In addition, as non-ejection detection, a method using temperature rise during ink ejection and a method of reading a check pattern printed on a recording member with a sensor or the like have been proposed. However, the former is indirect detection, and may not be detected when only one ejection port is non-ejection in a multi-ejection head, which is inferior in accuracy. In the latter, there is a problem that the recording member is wasted, and it takes time and effort.

In order to solve the above problems, a method as disclosed in Patent Document 1 has been proposed. In the method disclosed in Patent Document 1, light from a light emitting element is caused to pass through ink in a discharge port of a recording head and hit a light receiving element, and the ink in the discharge port is normal by the output of the light receiving element. Or an abnormality such as color mixing or ink dropping has been detected. According to this Patent Document 1, it is possible to detect in real time image quality deterioration factors such as ejection failure and color mixing of the recording means, and a recovery operation can be performed before the image quality is lowered. However, it is very complicated to install the light emitting element and the light receiving element so as to cross the flow path of each nozzle, and there are many problems to be solved in the manufacturing process. In addition, in a mode in which a DNA probe is ejected onto a substrate using an ink jet method, such as a DNA (Deoxyribonucleic Acid) chip manufacturing apparatus, each dot has a very important meaning for determination of a specimen, so ejection failure Would be a fatal fault. For this reason, it is required to reliably eliminate discharge defects.
JP 2000-085148 A

  The above-described conventional ink jet recording apparatus has a problem in that it is necessary to have a complicated configuration and a lot of trouble to detect a discharge failure, or it is necessary to waste a recording member and a discharge liquid.

  The present invention has been made in view of such technical problems, and an object of the present invention is to reliably detect ejection defects with a simple configuration and without wasting a recording member or ejection liquid. A liquid ejection apparatus and a liquid ejection method that can be used.

In order to achieve the above object, the present invention provides a liquid ejection device that ejects liquid onto a medium,
An ejection head for ejecting liquid onto the medium;
Photographing means for photographing the discharge head;
Image processing means for generating a difference image by subtracting a normal image from the image of the ejection head imaged by the imaging means;
Based on the difference image generated by the image processing means, the state of the face surface that is the surface facing the medium of the ejection head and the state in the flow path are detected, and whether or not the nozzle in the ejection head is a defective ejection nozzle Determination means for determining whether or not.

  According to the present invention, since a defective discharge nozzle is detected by generating a difference image between a photographed image of the ejection head and a normal image, the medium and the ejection liquid can be removed with a simple configuration. This makes it possible to reliably detect defective nozzles without wasting them, reliably preventing ejection from defective nozzles, and performing the recovery operation, ejection operation, and other non-ejection measures as appropriate. be able to.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a case where the present invention is applied to an ink jet recording apparatus will be described as an embodiment of the present invention.

(First embodiment)
FIG. 1 is an overall perspective view of the ink jet recording apparatus according to the first embodiment of the present invention.

  A Y-axis stage 53 and guide rails 57 and 58 are fixed in parallel on the surface plate 59. An X-axis stage 54 is attached to the movable parts of the Y-axis stage 53 and the guide rails 57 and 58, and the X-axis stage 54 is movable in the Y direction. A chuck θ stage 55 is fixed to the movable part of the X-axis stage 54, and a chuck 56 is fixed to the upper surface of the chuck θ stage 55. The chuck 56 is connected to a pump (not shown) by a tube, and the recording member 68 is adsorbed to the chuck 56 when the pump sucks air. A CCD (Charge Coupled Device) camera 14 is attached to the chuck 56 so that the entire face surface of the recording head 6 can be imaged. In addition, columns 65 and 66 are fixed on the surface plate 59, and bridges 63 and 64 are fixed to the columns 65 and 66, respectively. The bridges 63 and 64 are fixed by a stay 62, and the strength of the structures of the columns 65 and 66 and the bridges 63 and 64 is maintained. Further, a head θ stage 61 is fixed between the bridges 63 and 64, and the recording head 6 is fixed to the head θ stage 61. The ink jet recording apparatus is also provided with a recovery unit (not shown) for cleaning the recording head 6.

  FIG. 2 shows the recording head 6 as seen from the face side. The nozzles 1 are arranged in a matrix. Here, the face surface is a surface facing the recording member 68 of the recording head 6. Each of these nozzles 1 has an independent flow path, and is configured to have an opening so that the discharge liquid can be supplied from the back side of the paper surface by a pipetter or a dispensing device. 3 is a detailed view of the vicinity of the nozzle 1, FIG. 3 (a) is a view as seen from the face side, and FIG. 3 (b) is a cross-sectional view taken along line AA of FIG. 3 (a). The nozzle 1 is provided with a heater board 3 and an orifice plate 4, and the discharge liquid is supplied into the nozzle 1 from the ink supply hole 5. The orifice plate 4 may or may not be transparent. However, if it is not transparent, only the face surface can be imaged by the CCD camera 14, and the inside of the channel cannot be imaged.

  FIG. 4 shows a state in which bubbles and foreign matter that may cause non-discharge are present inside and outside the flow path of the nozzle 1. 4A shows a state in which foreign matter such as dust has entered the flow path, FIG. 4B shows a state in which foreign matter such as dust has adhered to the face surface, and FIG. When bubbles are present, FIG. 4D shows a case where foreign matters such as wiping residual liquid or thickened discharge liquid wrinkles adhere to the face surface. In the present invention, by performing image processing, it is possible to detect these bubbles and foreign matters that cause ejection failure.

  FIG. 5 is a control block diagram of the ink jet recording apparatus according to the present embodiment.

  As shown in FIG. 5, the inkjet recording apparatus according to the present embodiment includes a recording head 6 for ejecting ink onto a medium, an ejection controller 12, a CPU 10, a CCD camera 14, an image processing unit 13, An operation unit 17, a memory 11, a recovery unit 16, and a recovery controller 15 are provided.

  The entire apparatus is controlled by the CPU 10 serving as a control unit executing a program stored in the memory 11. The CPU 10 detects bubbles and foreign matters inside and outside the flow path of the nozzle 1, controls the recording head 6 via the discharge controller 12, and controls the recovery unit 16 via the recovery controller 15. Although not shown, the CPU 10 also controls the relative movement between the recording head 6 and the recording member 68. The recovery unit 16 functions as a recovery means for recovering the ejection failure of the recording head 6. Further, the recovery controller 15 functions as a recovery control unit that causes the recovery unit 16 to perform recovery processing on the defective ejection nozzle when the CPU 10 detects the defective ejection nozzle.

  An output image from the CCD camera 14 is input to the image processing unit 13 and subjected to image processing by a predetermined image processing program. In this image processing unit 13, an image of the area A of the normal nozzle 1 free from bubbles and foreign matters from an image in a predetermined range (area A in FIG. 4) in the image of the face surface of the recording head 6 captured by the CCD camera 14. Is subtracted to generate a difference image. By outputting the result to the CPU 10, bubbles and foreign matter inside and outside the flow path of the nozzle 1 are detected. That is, the CPU 10 detects the state of the face surface of the recording head 6 and the state in the flow path based on the difference image generated by the image processing unit 13, and determines whether the nozzle in the recording head is a defective ejection nozzle. It operates as a determination means for determining whether or not. The operation unit 17 is used to display information notified to the operator and to input an instruction from the operator. Further, the discharge controller 12 functions as a discharge control means for prohibiting the discharge from the nozzle when the CPU 10 detects the discharge nozzle and the recovery unit 16 does not recover the discharge failure.

  FIG. 6 is a flowchart showing the operation of the ink jet recording apparatus according to this embodiment. Here, it is assumed that the same discharge liquid is supplied to a plurality of nozzles and that there are a plurality of such discharge liquids.

  When the drawing process starts, the recording head 6 is recovered (suction / wipe) (step 101), and the nozzle is imaged by the CCD camera 14 (step 102). The processing in step 101 is not necessarily performed when printing is started without elapse of a predetermined time since the previous ejection. If the resolution of the CCD camera 14 is not sufficient to detect bubbles / foreign matter in the area A in FIG. 4 in step 102, the imaging area is divided into a plurality of areas (for example, as shown by the dotted lines in FIG. 2). Image). Further, in the case of capturing all the bubbles and foreign substances in the face surface of the recording head 6 and the flow path, if the depth of field of the CCD camera 14 is shallow, the image is shaken and imaged. In that case, the orifice plate 4 needs to be transparent.

  Next, the image processing unit 13 cuts out the area A for each nozzle from the image captured in step 102 and performs image processing (step 103), and the CPU 10 determines the discharge liquid based on the result of this image processing. It is determined whether or not all the nozzles that are filled have bubbles / foreign matter, that is, whether or not they are defective nozzles (step 104).

  Based on the result, a nozzle for discharging is selected from the nozzles containing the same liquid (step 105). If there are nozzles that are determined to be capable of discharging two or more of the same liquid, either one may be selected. After the ejection nozzle is determined in step 105, preliminary ejection (step 106) and drawing (step 107) are performed, and printing is completed.

  On the other hand, if all of the nozzles containing the same liquid are defective in discharge, the CPU 17 displays an error message and the address or / and liquid type of the defective discharge nozzle on the operation unit 17 (step 108). . At that time, the operation of the ink jet recording apparatus stops halfway. Next, in step 109, the same liquid as that in the nozzle is supplied to the spare nozzle by a pipetter or the like, and a recovery operation is performed as necessary. At that time, an address and a liquid type of the nozzle that supplies the liquid are input from the operation unit 17. The nozzle address and liquid type input here are added to the discharge nozzle selected in step 105, and the liquid is discharged onto the recording member 68 at the position where it should be discharged.

  According to the inkjet recording apparatus of this embodiment, the CCD camera 14 captures the face surface of the recording head 6 and subtracts the normal image from the image captured by the image processing unit 13 to obtain a difference image. The presence / absence of an ejection failure nozzle is determined. Therefore, according to the ink jet recording apparatus of the present embodiment, it is possible to reliably detect defective discharge nozzles with a simple configuration, and it is possible to prevent defective discharge by using a spare nozzle instead of the detected defective discharge nozzle. It becomes possible to prevent.

(Second Embodiment)
Next, an ink jet recording apparatus according to a second embodiment of the present invention will be described.

  In the first embodiment described above, the ejection from the defective ejection nozzle detected by the image processing is prevented in advance, and the preliminary nozzle is ejected. It is a recovery.

  FIG. 7 is a flowchart showing the operation of the ink jet recording apparatus according to this embodiment. Here, it is assumed that one liquid type is supplied per nozzle.

  When the drawing process starts, the recording head 6 is recovered (suction / wipe) (step 201), and the nozzle is imaged (step 202). The processing in step 203 is not necessarily performed when printing is started without a predetermined time since the previous ejection. In step 202, if the resolution of the CCD camera 14 is not sufficient to detect bubbles / foreign substances in the area A in FIG. 4, the imaging area is divided into a plurality of areas. Further, in the case of capturing all the bubbles and foreign substances in the face surface of the recording head 6 and the flow path, if the depth of field of the CCD camera 14 is shallow, the image is shaken and imaged. In that case, the orifice plate 4 needs to be transparent. The image captured in step 202 is subjected to image processing in area A (step 203) to determine whether or not all nozzles filled with the discharge liquid have bubbles / foreign matters, that is, whether or not the nozzle is a defective discharge nozzle. Determine. As a result, if there is no defective ejection nozzle, preliminary ejection (step 205) and drawing (step 206) are performed, and printing is completed.

  When it is determined in step 204 that there is a defective discharge nozzle, a recovery process is performed on the detected defective discharge nozzle (step 207). Next, the nozzle is imaged in the same manner as in steps 202 and 203 (step 208), and image processing is performed (step 209). Accordingly, it is determined whether or not the defective ejection nozzle has been recovered to the ejectable nozzle (step 210). Here, in step 208, the object to be imaged by the CCD camera 14 does not need to be the entire face surface of the recording head 6, but only needs to be able to cover defective nozzles. If all the recovered nozzles can be ejected as a result of the determination, the process continues to steps 205 and 206.

  If all the recovered nozzles cannot be ejected, an error message and the address or / and liquid type of the defective ejection nozzle are displayed on the operation unit 17 (step 211). At that time, the operation of the apparatus stops halfway. In step S14, the same liquid as that in the nozzle is supplied to the spare nozzle by a pipetter or the like, and a recovery operation is performed as necessary. At that time, an address and a liquid type of the nozzle that supplies the liquid are input from the operation unit 17. The nozzle address and liquid type input here are input to the CPU 10 and the liquid is discharged onto the recording member 68 at a position where it should be discharged. Subsequently, the process proceeds to steps 205 and 206, where printing is finished.

  In the present embodiment, the recovery process is performed before the drawing, but the present invention does not necessarily assume that. For example, even if there is a large time lag between the recovery process and the next drawing, more specifically, if the change in the state of the recording head is at a level that does not cause a problem with respect to ejection, more specifically, the viscosity of the ejection liquid or the As long as the generation of dust and bubbles from the discharge liquid in the recording head is not a problem with respect to the discharge, it may be after the recording head replacement, after the recording member replacement, or after drawing.

  During handling before replacing the recording head, dust may adhere to the recording head, the meniscus in the nozzle may be destroyed by the impact of handling, and the discharge liquid may leak out to the face surface, leaving it untouched until drawing. It may thicken and solidify. By performing the recovery operation upon receiving the image processing information after the recording head is replaced, it is possible to avoid the ejection failure that may occur from the face surface state as described above.

  Further, when the recording member is replaced, dust may be generated from the recording member and may adhere to the face surface of the recording head. However, after the recording member is replaced, a recovery operation is performed by receiving image processing information. As a result, it is possible to avoid ejection defects that may occur due to dust adhering to the recording head.

  In addition, at the time of drawing, the discharge liquid may adhere to the face surface of the recording head due to mist or the like. If the liquid is left for a long time, the discharge liquid may thicken and solidify. By receiving the image processing information after drawing and performing a recovery operation, the discharge liquid does not thicken or solidify on the face surface, and discharge failure at the next drawing can be avoided.

(Third embodiment)
Next, an ink jet recording apparatus according to a third embodiment of the present invention will be described.

  In the first and second embodiments described above, it is only determined whether or not the observed nozzle is a defective discharge nozzle. Therefore, the response when there is a defective discharge nozzle is always the same. It was. On the other hand, in this embodiment, not only whether the observed nozzle is a defective ejection nozzle, but also the same ejection failure nozzle is subdivided to determine the state of the nozzle while appropriately selecting the response to the nozzle. That's it. As a result, there is an opportunity to deal with the ejection failure nozzle without performing suction, and the opportunity for wasting ink is reduced.

  FIG. 8 is a flowchart showing the operation of the ink jet recording apparatus according to this embodiment. Here, it is assumed that one liquid type is supplied per nozzle.

  When the drawing process starts, the recording head 6 is recovered (suction / wipe) (step 301), and the nozzle is imaged (step 302). The processing in step 301 is not necessarily performed when printing is started without elapse of a predetermined time since the previous ejection. If the resolution of the CCD camera 14 is not sufficient to detect bubbles / foreign matter in the area A in FIG. 4 in step 302, the imaging area is divided into a plurality of areas. Further, in the case of capturing all the bubbles and foreign substances in the face surface of the recording head 6 and the flow path, if the depth of field of the CCD camera 14 is shallow, the image is shaken and imaged. In that case, the orifice plate 4 needs to be transparent. By processing the image captured in step 302 in area A (step 303), for all nozzles filled with the discharge liquid, (1) whether there is foreign matter in the flow path, (2) It is determined whether there are bubbles in the flow path, and (3) whether there are foreign objects on the face surface. (1) The distinction between (2) and (3) can be determined by the focus position. The difference between (1) and (2) is that the image after the difference is obtained by image processing is determined to be a bubble having a dark part around the outline and a bright part inside (see FIG. 4C). A pattern in which all of the surroundings and the interior are dark parts is determined to be a foreign substance (see FIG. 4A). If the difference image after image processing protrudes from the area A and cannot be determined as such even if it is actually a bubble, the case (1) is determined and handled.

  In step 304, if there is a nozzle that is determined to have foreign matter in the flow path, an error message and the address or / and liquid type of the ejection failure nozzle are displayed on the operation unit 17 (step 305). At that time, the operation of the apparatus stops halfway. Next, in step 306, the same liquid as that in the nozzle is supplied to the spare nozzle by a pipetter or the like, and a recovery operation is performed as necessary. At that time, an address and a liquid type of the nozzle that supplies the liquid are input from the operation unit 17. The nozzle address and liquid type input here are input to the CPU 10, and the liquid is discharged onto the recording member 68 at a position where it should be discharged. Subsequent to step 306 or if NO at step 304, the routine proceeds to step 307, where it is determined whether there is a nozzle with bubbles in the flow path. If there is at least one such nozzle that was scheduled to be ejected, suction and wiping are performed (step 308). If there is none, it is next checked whether there is a nozzle with foreign matter on the face (step 309). Therefore, if there is a foreign object, only wipe is performed (step 310), and if there is no foreign object, preliminary ejection (step 311), drawing (step 312), and printing end.

  In the present embodiment, when the CPU 10 does not detect a nozzle having a foreign substance in the flow channel and detects a nozzle having a bubble in the flow channel, the recovery controller 15 Then, the recovery unit 16 is instructed to perform the suction or pressure recovery and the wiping operation on the range including the nozzle.

  Then, in the CPU 10, a nozzle having a foreign substance in the flow path is not detected for the nozzle that was scheduled to be discharged, a nozzle having a bubble in the flow path is not detected, and a foreign substance exists on the face surface near the nozzle. When a nozzle that has been detected is detected, the recovery controller 15 instructs the recovery unit 16 to perform a wiping operation on a range including the nozzle.

  In the first to third embodiments, the print system of the recording head is not particularly mentioned. However, the present invention is not limited to the print system of the print head, and generates heat energy to cause film boiling. The same applies to a bubble jet (registered trademark) type head having an electrothermal transducer to be generated, and a head of a type in which pressure is applied by a piezo element to an ink chamber in a nozzle and ink droplets are ejected to record. It can be applied to.

  Furthermore, in the first to third embodiments, the case where the present invention is applied to an ink jet recording apparatus that forms characters and images by ejecting ink onto a recording medium has been described. A liquid discharge apparatus that discharges liquid onto a medium by including a discharge head that can discharge liquid can be similarly applied.

1 is an overall perspective view of an ink jet recording apparatus according to a first embodiment of the present invention. 2 is a diagram illustrating a face surface of a recording head 6. FIG. 2 is a detailed view of the nozzle 1. FIG. It is the figure which looked at the nozzle in which a bubble and a foreign material existed from the face side. FIG. 2 is a control block diagram of the ink jet recording apparatus according to the first embodiment of the present invention. 3 is a flowchart showing the operation of the ink jet recording apparatus according to the first embodiment of the present invention. It is a flowchart which shows operation | movement of the inkjet recording device of the 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the inkjet recording device of the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Nozzle port 3 Heater board 4 Orifice plate 5 Supply hole 6 Recording head 10 CPU
11 Memory 12 Discharge Controller 13 Image Processing Unit 14 CCD Camera 15 Recovery Controller 16 Recovery Unit 17 Operation Unit 53 Y Axis Stage 54 X Axis Stage 55 Chuck θ Stage 56 Chuck 57, 58 Guide Rail 59 Surface Plate 61 Head θ Stage 63, 64 Bridge 65, 66 Post 68 Recording member

Claims (15)

A liquid ejection device for ejecting liquid to a medium,
An ejection head for ejecting liquid onto the medium;
Photographing means for photographing the discharge head;
Image processing means for generating a difference image by subtracting a normal image from the image of the ejection head imaged by the imaging means;
Based on the difference image generated by the image processing means, the state of the face surface that is the surface facing the medium of the ejection head and the state in the flow path are detected, and whether or not the nozzle in the ejection head is a defective ejection nozzle A liquid ejecting apparatus comprising: determination means for determining whether or not   The liquid ejection apparatus according to claim 1, wherein an orifice plate provided on a face surface of the ejection head is transparent.   3. The liquid according to claim 1, wherein the state in the flow path is the presence or absence of bubbles in the flow path and foreign matter in the flow path, and the state of the face surface is the presence or absence of foreign matter attached to the face surface. Discharge device. Recovery means for recovering the ejection failure of the ejection head;
4. The recovery control unit according to claim 1, further comprising: a recovery control unit configured to perform a recovery process by the recovery unit on the defective discharge nozzle when the determination unit detects the defective discharge nozzle. 5. Liquid ejection device.   The liquid ejection apparatus according to claim 4, further comprising: a ejection control unit that prohibits ejection from the nozzle when the ejection failure nozzle is detected by the determination unit and the ejection failure is not recovered by the recovery unit.   In the determination unit, when a nozzle having a foreign substance in the flow channel is not detected for the nozzle scheduled to be discharged and a nozzle having a bubble in the flow channel is detected, the recovery control unit The liquid ejecting apparatus according to claim 4, wherein the recovery unit is instructed to perform suction or pressure recovery and a wiping operation on a range including the nozzle.   In the determination means, a nozzle having a foreign substance in the flow path is not detected for the nozzle that was scheduled to be discharged, a nozzle having a bubble in the flow path is not detected, and a foreign substance exists on the face surface near the nozzle. 5. The liquid ejection apparatus according to claim 4, wherein, when a nozzle is detected, the recovery control unit instructs the recovery unit to perform a wiping operation on a range including the nozzle.   The liquid ejection apparatus according to claim 1, wherein the ejection head is a bubble jet (registered trademark) type head including an electrothermal transducer that generates thermal energy to cause film boiling.   8. The liquid ejection apparatus according to claim 1, wherein the ejection head is a head of a system in which a pressure is applied to an ink chamber in a nozzle by a piezo element and ink droplets are ejected for recording. 9. A liquid discharge method for discharging liquid to a medium,
Photographing a discharge head for discharging liquid onto a medium;
Subtracting a normal image from the image of the ejected ejection head to generate a differential image;
Based on the generated difference image, the state of the face surface that is the surface facing the medium of the ejection head and the state in the flow path are detected, and it is determined whether or not the nozzle in the ejection head is a defective ejection nozzle. And a liquid ejection method comprising the steps.   The liquid ejection method according to claim 10, wherein the state in the flow path is the presence or absence of bubbles in the flow path and foreign matter in the flow path, and the state of the face surface is the presence or absence of foreign matter attached to the face surface.   The liquid ejection method according to claim 10, further comprising a step of performing a recovery process for the ejection failure nozzle when the ejection failure nozzle is detected.   The liquid ejection method according to claim 12, further comprising a step of prohibiting ejection from the nozzle when the ejection failure nozzle is detected and the ejection failure is not recovered even though the recovery process is performed.   In the step of performing the recovery process on the detected defective discharge nozzle, a nozzle having a foreign substance in the flow channel is not detected and a nozzle having a bubble in the flow channel is detected for the nozzle that was scheduled to be discharged. The liquid discharge method according to claim 12, wherein in the case where the ink is discharged, suction or pressure recovery and a wiping operation are performed on a range including the nozzle.   In the step of performing the recovery process on the detected defective discharge nozzle, a nozzle having a foreign substance in the flow channel is not detected and a nozzle having a bubble in the flow channel is detected for the nozzle that was scheduled to be discharged. The liquid according to claim 12, wherein the recovery control unit performs a wiping operation on a range including the nozzle when a nozzle having a foreign object on the face surface near the nozzle is detected. Discharge method.

Images