JP2005178290A - Liquid droplet jet device and method of detecting ejection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet jet device capable of detecting defective ejection during the printing operation, reducing the numbers of light sources and photoreceptor elements as compared to the number of nozzles, simplifying a head structure, and reducing the cost, and to provide a method of detecting ejection. <P>SOLUTION: Waveguides 53A, 53B contacting the nozzles 51 are provided on a nozzle plate 52 of a print head 50 by each nozzle row. The light source 54 and a lens 55 for coupling are provided on one end of the waveguide 53A and a lens 57 for coupling and the photoreceptor element 56 are provided on one end of the waveguide 53B. When forming an image, operations of pulling meniscuses are carried out in the plurality of nozzles at the same time. By detecting a quantity of the light entering the photoreceptor element 56, the action of the meniscus is detected, and then it is judged whether or not there is an ejection defective nozzle. When there is a defective nozzle, the printing operation is interrupted, and then a recovery operation is carried out. It is preferable to carry out the recovery operation by each nozzle block. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a droplet discharge device and a discharge detection method, and more particularly, to a droplet discharge device suitable for detecting a discharge failure nozzle in an inkjet head having a plurality of droplet discharge holes (nozzles) and a discharge detection method thereof.

  An ink jet recording apparatus forms an image on a recording medium by ejecting ink from the nozzles while relatively moving a recording head in which a plurality of nozzles are arranged and the recording medium. In this type of apparatus, ink is no longer ejected from the nozzles due to ink thickening or air bubble contamination, or the amount of ink ejected (dot size to be ejected onto the recording medium) or the position of ink ejection is inadequate. There may be a case where ejection failure such as appropriateness occurs.

  For this reason, conventionally, a method such as irradiating a droplet discharged from a recording head with light such as laser light and detecting non-ejection by the light transmittance, and printing a test pattern on a recording medium and reading the pattern A method for detecting non-ejection is known. However, these methods are difficult to detect during the printing operation, and the throughput decreases.

In order to deal with this problem, Patent Document 1 and Patent Document 2 are not effective by providing optical detection means (light source and light receiving element) for each nozzle and detecting the meniscus position (position of the interface between ink and outside air). A method for performing a discharge inspection has been proposed.
JP-A 63-197656 JP-A-5-338161

  However, the methods proposed in Patent Document 1 and Patent Document 2 require an optical detection means for each nozzle, which complicates the head configuration and leads to an increase in cost. In particular, the problem becomes remarkable in a recording head having a high-density nozzle array structure used for high-resolution image recording.

  The present invention has been made in view of such circumstances, and enables detection of ejection failure during a printing operation and simplifies the head structure by reducing the number of light sources and light receiving elements compared to the number of nozzles. It is another object of the present invention to provide a droplet discharge device and a discharge detection method that can realize cost reduction.

  In order to achieve the above object, a droplet discharge device according to a first aspect of the present invention includes a nozzle row in which a plurality of nozzles for discharging droplets are arranged, and the nozzle row provided corresponding to the nozzle row. A waveguide that forms a part of the wall surfaces of the plurality of nozzles constituting the light source, a light source that generates light to be introduced into the waveguide, and light that is propagated through the waveguide is received and the amount of light received A light receiving means for outputting a corresponding signal, and applying a pressure change to the liquid in the pressure chamber communicating with the nozzle to advance and retract the meniscus in the nozzle along the discharge direction, thereby changing the position of the meniscus with respect to the waveguide. A meniscus driving unit; and a determination unit that determines the presence or absence of a defective nozzle based on a signal obtained from the light receiving unit as the meniscus moves by the meniscus driving unit. To.

  Nozzles that fail to discharge are found to be abnormal in the meniscus pull-in and return operations, so the droplet discharge device of the present invention uses an optical system in which the amount of light propagated in the waveguide varies according to the movement of the meniscus. It is configured, and the presence or absence of a defective nozzle is determined by detecting the fluctuation in the amount of light by the light receiving element. According to the present invention, since a waveguide shared by a plurality of nozzles constituting a nozzle row, a light source, and a light receiving element are used, the presence or absence of a defective nozzle can be determined on a nozzle row basis. Further, it is possible to detect ejection of a plurality of nozzles by using a smaller number of light sources and light receiving elements than the number of nozzles, and it is possible to realize a simplified head structure and cost reduction.

  According to a second aspect of the present invention, there is provided the droplet discharge device according to the first aspect, wherein the first waveguide and the second waveguide are disposed on both sides of the nozzle row with the nozzle row interposed therebetween. The light source is disposed at one end of the waveguide and the light receiving element is disposed at the other end, and a part of the light propagating through the first waveguide depends on the position of the meniscus. It is configured to pass through the liquid inside and enter the second waveguide.

  According to the aspect of the second aspect, since the light leaking from the first waveguide into the nozzle passes through the liquid in the nozzle and is released to the second waveguide, the detection sensitivity is improved.

  According to a third aspect of the present invention, there is provided the droplet discharge device according to the first aspect, wherein the first waveguide and the second waveguide are disposed on both sides of the nozzle row with the nozzle row interposed therebetween. The light source is disposed at the end of the waveguide, the light receiving element is disposed at the end of the second waveguide, and a part of the light propagating through the first waveguide is located at the position of the meniscus. Accordingly, it has a structure in which it passes through the liquid in the nozzle and enters the second waveguide, and is received by the light receiving element through the second waveguide.

  According to the third aspect of the present invention, the light that passes through the liquid in the nozzle and enters the second waveguide is detected by the light receiving element. In this aspect, detection is performed in the same manner as in the second aspect. An improvement in sensitivity can be achieved.

  According to a fourth aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the first to third aspects, when the determination unit determines that there is a defective nozzle, the recovery process is performed for the nozzle row. A recovery means is provided.

  By performing the recovery process for the nozzle row including the defective nozzle in units of nozzle rows, it is possible to reduce the ink consumption and increase the efficiency of the recovery operation.

  According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus using the liquid droplet ejection apparatus according to any one of the first to fourth aspects, wherein the nozzle array in which the plurality of nozzles are arranged and the waveguide are provided. An inkjet recording apparatus is provided that records an image on the recording medium by ejecting ink droplets from the nozzle while moving the recording medium relative to a recording head including the recording head.

  In the ink jet recording apparatus of the present invention, the form of the recording head is not particularly limited, and may be a shuttle type recording head that performs printing while the recording head reciprocates in a direction substantially orthogonal to the feeding direction of the recording medium. A full-line type recording head having a nozzle array in which a plurality of nozzles that eject ink are arranged in a direction substantially orthogonal to the feeding direction of the recording medium over a length corresponding to the entire width of the recording medium may be used.

  The “full-line type recording head (droplet discharge head)” is usually arranged along a direction perpendicular to the relative feeding direction of the recording medium, but is in a predetermined direction with respect to the direction perpendicular to the feeding direction. There may also be a mode in which the recording head is arranged along an oblique direction having the angle. Further, the arrangement form of the nozzles in the recording head is not limited to a single line arrangement, and may be a matrix arrangement (two-dimensional arrangement) composed of a plurality of rows. Furthermore, by combining a plurality of short recording head units having nozzle rows that are less than the length corresponding to the entire width of the recording medium, a nozzle row corresponding to the entire width of the recording medium may be configured as a whole of these units. .

  The “recording medium” is a medium (which can be called a print medium, an image forming medium, a recording medium, an image receiving medium, or the like) that receives an image by the action of a recording head, and is a continuous sheet, a cut sheet, a seal sheet, It includes various media regardless of the material and shape, such as a resin sheet such as an OHP sheet, a film, a cloth, a printed board on which a wiring pattern or the like is formed by an inkjet recording apparatus. In this specification, the term “printing” represents the concept of forming an image in a broad sense including characters.

  The moving means (conveying means) for moving the recording medium and the recording head relatively moves the recording medium relative to the stopped (fixed) recording head, and moves the recording head relative to the stopped recording medium. Either the aspect or the aspect in which both the recording head and the recording medium are moved is included.

  A sixth aspect of the present invention relates to the ink jet recording apparatus according to the fifth aspect, wherein the presence or absence of an ejection failure nozzle is detected based on a detection signal from the light receiving means during an image recording operation on the recording medium by the recording head. It is determined.

  By performing detection during image formation (during printing operation), there is an advantage that there is no decrease in throughput.

  The invention according to claim 7 provides a method invention for achieving the object. That is, the discharge detection method according to claim 7 is a droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged, and part of wall surfaces of the plurality of nozzles constituting the nozzle row. In addition, a waveguide is formed so that light emitted from a light source is guided into the waveguide, and the light propagating through the waveguide is received by a light receiving means to obtain a signal corresponding to the amount of light received. By applying a pressure change to the liquid in the pressure chamber communicating with the nozzle, causing the meniscus in the nozzle to advance and retreat in the discharge direction, and changing the position of the meniscus with respect to the waveguide. The presence / absence of a defective nozzle is determined based on a signal obtained from the light receiving means in accordance with the movement of the meniscus.

  According to the present invention, the movement of the meniscus is optically detected using a waveguide, a light source, and a light receiving element shared by a plurality of nozzles constituting the nozzle row. With a small number of light sources and light receiving elements, discharge detection of a plurality of nozzles can be performed, and the head structure can be simplified and the cost can be reduced.

  Further, in the ink jet apparatus using the droplet discharge apparatus according to the present invention, high throughput can be realized by performing detection during the image recording operation.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus using a droplet discharge device according to an embodiment of the present invention. As shown in the figure, the inkjet recording apparatus 10 includes a print unit 12 having a plurality of print heads 12K, 12C, 12M, and 12Y provided for each ink color, and each print head 12K, 12C, 12M, An ink storage / loading unit 14 for storing ink to be supplied to 12Y, a paper feeding unit 18 for supplying recording paper 16, a decurling unit 20 for removing curling of the recording paper 16, and a nozzle of the printing unit 12 The suction belt transport unit 22 that transports the recording paper 16 while maintaining the flatness of the recording paper 16 and the recorded recording paper (printed material) are discharged to the outside. And a paper discharge unit 26.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is disposed on the printing surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least a portion facing the nozzle surface of the printing unit 12 forms a horizontal surface (flat surface). Has been.

  The belt 33 has a width that is wider than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, a suction chamber 34 is provided at a position facing the nozzle surface of the printing unit 12 inside the belt 33 spanned between the rollers 31 and 32, and the suction chamber 34 is connected to the fan 35. The recording paper 16 on the belt 33 is sucked and held by suctioning to negative pressure.

  When the power of a motor (not shown in FIG. 1, described as reference numeral 88 in FIG. 6) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 rotates in the clockwise direction in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the print area, the image easily spreads because the roller contacts the printing surface of the sheet immediately after printing. There is a problem. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 12 is a so-called full line type head in which line type heads having a length corresponding to the maximum paper width are arranged in a direction orthogonal to the paper feed direction (see FIG. 2). Although a detailed structural example will be described later, each of the print heads 12K, 12C, 12M, and 12Y has a length that exceeds at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10, as shown in FIG. A line type head in which a plurality of ink discharge ports (nozzles) are arranged is formed.

  A print head 12K corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording paper 16 (hereinafter referred to as the paper transport direction). , 12C, 12M, and 12Y are arranged, and color images can be formed on the recording paper 16 by ejecting the color inks from the print heads 12K, 12C, 12M, and 12Y while conveying the recording paper 16, respectively.

  As described above, according to the printing unit 12 in which the full line head that covers the entire width of the paper is provided for each ink color, the recording paper 16 and the printing unit 12 are relatively moved in the paper feeding direction (sub-scanning direction). It is possible to record an image on the entire surface of the recording paper 16 with only one operation (that is, with one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the print head reciprocates in the main scanning direction, and productivity can be improved.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink may be added as necessary. Good. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 includes tanks (ink tanks) that store inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y, and each ink tank is not shown. The print heads 12K, 12C, 12M, and 12Y communicate with each other through the pipe line. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  A post-drying unit 42 is provided following the printing unit 12. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by blocking the paper holes by pressurization. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) that switches the paper discharge path so as to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Print head structure]
Next, the structure of the print head will be described. Since the structures of the print heads 12K, 12C, 12M, and 12Y provided for the respective ink colors are common, the print heads are represented by reference numeral 50 in the following.

  FIG. 3 is a perspective plan view when the print head 50 is viewed from the ejection surface (nozzle surface) side. 3, reference numeral 51 denotes a nozzle, 52 denotes a nozzle plate, 53 denotes a waveguide embedded in the nozzle plate 52, 54 denotes a light source, 55 denotes a lens, 56 denotes a light receiving element, and 57 denotes a lens.

  In the example shown in FIG. 3, two nozzle rows are formed along the longitudinal direction of the head (the horizontal direction in the figure). In FIG. 3, the nozzles 51 constituting each nozzle row are arranged at a constant pitch P, and the other nozzle row is shifted by 1/2 pitch in the row direction with respect to one nozzle row, so-called staggered nozzles It is an array. Thereby, the substantial nozzle interval (projection nozzle pitch) projected so as to be aligned along the head longitudinal direction (direction orthogonal to the conveyance direction of the recording paper 16) is P / 2.

  Each nozzle row is provided with waveguides 53A and 53B on both sides (upper and lower sides in FIG. 3) across the nozzle row. The waveguides 53A and 53B are provided in contact with the outer periphery of the nozzle 51 and in parallel with the nozzle row. A light source 54 and a coupling lens 55 are disposed at the end of the waveguide 53A on one side, and light emitted from the light source 54 is introduced into the waveguide 53A via the lens 55. As the light source 54, for example, a light emitting diode (LED) or a laser diode (LD) can be used.

  A coupling lens 57 and a light receiving element 56 are disposed at the other end of the waveguide 53A. The light propagated through the waveguide 53A is guided to the light receiving element 56 through the lens 57. The light receiving element 56 is a sensor that outputs an electrical signal corresponding to the amount of received light, and the ejection / non-ejection of the nozzle 51 is determined based on the detection signal obtained from the light receiving element 56. Details of the determination method will be described later.

  FIG. 4 is a cross-sectional view showing a three-dimensional configuration of one ejection element (an ink chamber unit corresponding to one nozzle 51). As shown in the figure, the print head 50 is manufactured by laminating and bonding a plurality of plate members (52, 502 to 507), and in the inside thereof, a pressure chamber 512, a common flow path 514, and an individual supply. A mouth 516, a nozzle channel 518, and the like are formed.

  The nozzle 51 is formed in the nozzle plate 52 as a final throttle portion for discharging the liquid, and is brought into contact with the wall surface of the nozzle 51 within a certain depth d from the opening side of the tip of the nozzle 51. A waveguide 53 is embedded. The waveguide 53 has a refractive index substantially equal to the refractive index of the ink used. The nozzle plate with the waveguide is formed by using a known method as shown in “Optical Integrated Circuit” (Hiroshi Nishihara et al., Ohm Co., Ltd.), etc. A waveguide is formed. Thereafter, the nozzle 51 is formed by machining or etching.

  The flow path plates 502 to 506 forming the flow path in the head are formed by forming holes or grooves in a thin plate material such as a SUS plate by etching or pressing, and a plurality of these flow path plates 502 to 506 are joined. The required flow path is configured.

  That is, the nozzle 51 communicates with the pressure chamber 512 via the nozzle channel 518, and the pressure chamber 512 communicates with the common channel 514 via the individual supply port 516. The common flow path 514 communicates with an ink tank (not shown in FIG. 4; indicated as 60 in FIG. 5) serving as an ink supply source, and the ink supplied from the ink tank 60 passes through the common flow path 514 in the head. The pressure chambers 512 are distributed and supplied.

  As shown in FIG. 4, an actuator 524 having an individual electrode 522 is joined to a pressure plate (vibration plate) 507 constituting the top surface of the pressure chamber 512, and a drive voltage is applied to the individual electrode 522. As a result, the actuator 524 is deformed and the volume of the pressure chamber 512 is changed, and ink is ejected from the nozzles 51 due to the pressure change accompanying this. Note that a piezoelectric body such as a piezoelectric element is preferably used for the actuator 524. After ink ejection, new ink is supplied to the pressure chamber 512 from the common channel 514 through the individual supply port 516.

[Configuration of ink supply system]
FIG. 5 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink tank 60 is a base tank for supplying ink to the print head 50, and is installed in the ink storage / loading unit 14 described with reference to FIG. In the form of the ink tank 60, there are a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink tank 60 in FIG. 5 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  As shown in FIG. 5, a filter 62 is provided in the middle of the conduit connecting the ink tank 60 and the print head 50 to remove foreign matter and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter of the print head 50 (generally, about 20 μm).

  Although not shown in FIG. 5, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A.

  The maintenance unit including the cap 64 and the cleaning blade 66 can be moved relative to the print head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the print head 50 as necessary. The

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The cap 64 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the print head 50, thereby covering the nozzle area of the nozzle surface 50 </ b> A with the cap 64.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the ink ejection surface (surface of the nozzle plate 52) of the print head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matters adhere to the nozzle plate 52, the cleaning blade 66 is slid on the nozzle plate 52 to wipe the nozzle surface 50A and clean the surface of the nozzle plate 52.

  During printing or standby, when a specific nozzle 51 is used less frequently and the ink viscosity in the vicinity of the nozzle increases, preliminary ejection is performed toward the cap 64 to discharge the deteriorated ink.

  When air bubbles are mixed in the ink in the print head 50 (in the pressure chamber 512), the cap 64 is applied to the print head 50, and the suction pump 67 removes the ink in the pressure chamber (ink mixed with air bubbles) by suction. Then, the sucked and removed ink is sent to the collection tank 68. In this suction operation, the deteriorated ink with increased viscosity (solidified) is sucked out when the ink is initially loaded into the head or when the ink is used after being stopped for a long time.

  That is, if the print head 50 does not discharge for a certain period of time, the ink solvent in the vicinity of the nozzles evaporates and the viscosity of the ink in the vicinity of the nozzles increases, and the nozzles even when the discharge driving actuator 524 operates. Ink is no longer ejected from 51. Therefore, before this state is reached (within the viscosity range in which ink can be discharged by the operation of the actuator 524), the actuator 524 is operated toward the ink receiver to discharge ink in the vicinity of the nozzle whose viscosity has increased. “Preliminary discharge” is performed. Further, after the dirt on the surface of the nozzle plate 52 is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, foreign matter is prevented from being mixed into the nozzle 51 by this wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  Further, if bubbles are mixed into the nozzle 51 or the pressure chamber 512 or if the viscosity of the ink in the nozzle 51 exceeds a certain level, ink cannot be ejected by the preliminary ejection, and the suction operation described below is performed.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 512, or when the ink viscosity in the nozzle 51 rises to a certain level or more, the ink can be ejected from the nozzle 51 even if the actuator 524 is operated. Disappear. In such a case, a suction means for sucking ink in the pressure chamber 512 with a pump or the like is brought into contact with the nozzle surface 50A of the print head 50, and an operation of sucking ink mixed with bubbles or thickened ink is performed.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 512, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. The cap 64 described in FIG. 5 functions as a suction unit and can also function as a preliminary discharge ink receiver.

  Preferably, the inside of the cap 64 is divided into a plurality of areas corresponding to the nozzle rows by a partition wall, and each of the partitioned areas can be selectively sucked by a selector or the like.

[Explanation of control system]
Next, the control system of the inkjet recording apparatus 10 will be described.

  FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, an image memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, an ejection detection control unit 85, and the like. .

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB, IEEE 1394, Ethernet, and wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the image memory 74. The image memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The image memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 is a control unit that controls each unit such as the communication interface 70, the image memory 74, the motor driver 76, and the heater driver 78. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the image memory 74, and the like, as well as a transport system motor 88 and heater 89. A control signal for controlling is generated.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives the heaters 89 of the post-drying unit 42 and other units in accordance with instructions from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from the image data in the image memory 74 according to the control of the system controller 72, and the generated print A control unit that supplies a control signal (print data) to the head driver 84. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the print head 50 are controlled via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 6, the image buffer memory 82 is shown in a form associated with the print control unit 80, but it can also be used as the image memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  The head driver 84 drives the ejection drive actuator 524 of the print head 50 for each color based on the print data given from the print controller 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

  Image data to be printed is input from the outside via the communication interface 70 and stored in the image memory 74. At this stage, for example, RGB image data is stored in the image memory 74. The image data stored in the image memory 74 is sent to the print control unit 80 via the system controller 72, and the print control unit 80 converts it into dot data for each ink color by a known method such as dithering or error diffusion. Converted.

  Thus, the print head 50 is driven and controlled based on the dot data generated by the print control unit 80, and ink is ejected from the print head 50. An image is formed on the recording paper 16 by controlling ink ejection from the print head 50 in synchronization with the conveyance speed of the recording paper 16.

  The discharge detection control unit 85 includes a light source control circuit that controls lighting (ON) / extinguishing (OFF) of the light source 54 in the print head 50 and a light emission amount at the time of lighting, a drive circuit for the light receiving element 56 in the print head 50, and And a signal processing circuit for processing a detection signal from the light receiving element 56. The discharge detection control unit 85 controls the operation of the light source 54 and the light receiving element 56 in accordance with a command from the print control unit 80, and provides the detection result obtained from the light receiving element 56 to the print control unit 80.

  The print control unit 80 determines whether or not the nozzle 51 is discharged based on the detection information obtained through the discharge detection control unit 85, and performs control to perform a predetermined recovery operation when a non-discharge nozzle is detected. Do.

[Principle of discharge detection]
Here, the principle of ejection detection in this embodiment will be described.

  7A is a cross-sectional view of the nozzle portion, and FIG. 7B is a view as seen from the ejection surface side. As shown in FIG. 7A, the meniscus 93 of the ink 92 is drawn into the nozzle 51, and from the thickness d of the waveguides 53A and 53B (the height d of the waveguide 53 in FIG. 7A). In the state where the meniscus surface is located at a deeper position, the light propagating in the waveguide 53A remains confined in the waveguide 53A. That is, the walls of the waveguides 53A and 53B constituting part of the wall surface of the nozzle 51 are in contact with air, and light is totally reflected in the waveguide 53A and does not leak outside. Therefore, as shown in FIG. 7B, the light beam advances through the waveguide 53A without a great loss of light quantity.

  On the other hand, as shown in FIG. 8A, in a state where the meniscus surface is not sufficiently drawn, that is, in a state where the waveguides 53A, 53B and the meniscus 93 are in contact with each other, the refractive index and the conductivity of the ink 92 are reduced. Since the refractive indexes of the waveguides 53A and 53B are substantially equal, light is not totally reflected at the contact portion of the nozzle 51 in the waveguide 53A, and part of the light leaks in the ink direction in the nozzle 51. Therefore, the light traveling in the waveguide 53A decreases.

  In order to draw the meniscus 93 and move the meniscus 93 to the state as shown in FIG. 7, it is performed by generating and applying a driving waveform that does not discharge or changing the internal pressure of the supply system. Can do.

  Therefore, the position of the meniscus surface can be detected by detecting the above-described light amount difference by the light receiving element 56. If the meniscus 93 is operating normally with respect to the drive command of the actuator 524 in each discharge element, normal discharge can be performed, and conversely, normal discharge cannot be performed for a discharge element in which the movement of the meniscus 93 is abnormal. Therefore, the ejection / non-ejection can be indirectly determined by detecting the movement of the meniscus 93.

  Specifically, at least one of (1) light quantity fluctuation due to the meniscus 93 being pulled in and (2) light quantity fluctuation for the meniscus 93 to return to discharge or settling is detected and stored. Judging by comparing with the correct fluctuation data (reference data).

  By simultaneously performing drawing operation for a plurality of nozzles and detecting fluctuations in the amount of light, it is determined whether or not there are defective (NG) nozzles in these nozzles. Further, it is possible to specify the NG nozzle by performing the pull-in operation of one nozzle for one detection system and detecting the light quantity fluctuation.

  When the NG nozzle is present, the printing operation is interrupted and the recovery operation is performed. When the inspection is performed for each nozzle block, the recovery operation is preferably performed for each block. If the inspection is OK (no NG nozzle), printing is continued.

  FIG. 9 shows an example of a detection output waveform of the light receiving element 56 (in the case of no defective nozzle). FIG. 9 shows the detection output waveform when there is no defective nozzle in the nozzle row in contact with the common waveguide 53. That is, in the reference state in which the actuator 524 is not driven, the meniscus 93 is close to the nozzle surface 50A (see FIG. 8A), and the ink 92 is in contact with the waveguide 53A. Some of the propagating light crosses the ink 92 in the nozzle 51. Therefore, the amount of light received by the light receiving element 56 is relatively small, and the detection signal at this time has a value indicated by V1 in FIG.

  Thereafter, the light receiving amount is increased by driving the actuators 524 corresponding to the respective nozzles 51 in the nozzle row all at once (simultaneously) to the pressure reducing side to perform the drawing operation of the meniscus 93, and the meniscus 93 is guided to the waveguides 53A and 53B. The maximum amount of received light is obtained when moving away from (in the state of FIG. 7A). The detection signal at this time is the maximum value indicated by V2 in FIG. Thereafter, when the meniscus 93 is returned to the original position, the detection signal also returns to the value of V1.

  10A to 10C are examples of detection output waveforms when a defective nozzle is present in the nozzle row. FIG. 10A shows a detection waveform when the meniscus 93 does not move at all. FIG. 10B shows a detection waveform when the meniscus 93 is pulled in but is not recovered. FIG. 10 (c) shows a detection waveform when it is in a retracted state and recovered.

  FIG. 11 is a flowchart showing an operation sequence in the ink jet recording apparatus according to the present embodiment.

  When a print instruction command operation is entered (step S110), the light source 54 for ejection detection is turned on (step S112), and the print operation is started (step S114). In response to the discharge clock, the meniscus 93 is pulled in for a plurality of nozzles that have the possibility of simultaneous discharge (step S116).

  With respect to the one in which the meniscus 93 has been pulled in, light amount detection is performed according to the detection principle described above, and OK / NG is determined (step S118). That is, OK / NG is determined by comparing the output waveform of the light receiving element 56 with the reference data. If “OK” in step S118, the detection operation returns to step S116 according to the discharge clock, and the discharge operation proceeds to step S120.

  In step S120, it is determined whether or not to perform printing discharge for each nozzle 51 on which the meniscus has been drawn. In the case of the nozzle 51 that performs discharge, a discharge waveform is input to the actuator 524 of the nozzle 51 (step S122), and droplets are discharged from the nozzle 51 (step S124). On the other hand, for the nozzle 51 that does not perform ejection in the determination process of step S120, a static waveform is input to the actuator 524 of the nozzle 51 (step S126), and the meniscus 93 is returned to the original reference position. , Non-ejection (step S128). After step S124 or step S128, the process returns to step S116 according to the ejection clock.

  If “NG” determination is obtained in the light quantity inspection in step S118, the process proceeds to step S130, and the recovery operation of the nozzle 51 is performed. Examples of the recovery operation include a plurality of meniscus vibrations, preliminary ejection, and suction cleaning. A mode in which the recovery operation is performed in units of nozzle rows that are determined to be NG is preferable.

  After the recovery operation in step S130, the meniscus 93 is drawn again for a plurality of nozzles that may be simultaneously ejected (step S132), and a light quantity inspection is performed (step S134). If “OK” is determined in the OK / NG determination by the light amount inspection in step S134, printing is resumed from the paper (recording paper 16) stop state. Or, discard the paper that became NG during printing and start printing from the beginning. In the former case, the detection operation returns to step S116 according to the ejection clock. In the latter case, the detection operation returns to step S114. If the light quantity inspection in step S134 results in NG determination, the process returns to step S130 and a recovery operation is performed.

[Modification 1]
FIG. 12 is a plan perspective view of a print head showing another embodiment of the present invention. In FIG. 12, members that are the same as or similar to those in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted.

  In the example shown in FIG. 12, the waveguide 53B in the configuration of FIG. 3 is omitted, and only one waveguide 53 is provided for one nozzle row.

  In the case of the configuration described with reference to FIG. 3, since the light that has crossed the ink 92 in the nozzle 51 is guided to the waveguide 53B on the opposite side, the detection accuracy is better than that of the configuration of FIG. On the other hand, the configuration of FIG. 12 does not have the waveguide 53B that receives the light that has entered the ink 92 in the nozzle 51, and therefore has an advantage that the head structure is simpler than the configuration of FIG. .

[Modification 2]
FIG. 13 is a plan perspective view of a print head showing still another embodiment of the present invention. In FIG. 13, members that are the same as or similar to those in FIG.

  The configuration example shown in FIG. 13 is common to the example of FIG. 3 in that two waveguides 53A and 53B are provided across one nozzle row, but the arrangement structure of the light receiving elements 56 is different.

  That is, in the print head 50 shown in FIG. 13, the light source 54 and the coupling lens 55 are arranged at the end of the waveguide 53A on one side, and the waveguide 51B on the opposite side across the nozzle 51 is disposed. A coupling lens 57 and a light receiving element 56 are disposed at the ends.

  In the configuration shown in FIG. 13, the light receiving element 56 detects light that has passed through the ink in the nozzle 51 and entered the waveguide 53 </ b> B. An example of the detection output waveform of the light receiving element 56 in the example of FIG. 13 (in the case of no defective nozzle) is shown in FIG. In the reference state in which the actuator 524 is not driven, the meniscus 93 is in a position near the nozzle surface 50A (see FIG. 8A), and the ink 92 and the waveguide 53 are in contact with each other. The ink 92 is traversed. For this reason, the amount of received light is relatively large, and the detection signal at this time has a value indicated by V3 in FIG.

  Thereafter, when the actuators 524 corresponding to the respective nozzles 51 in the nozzle row are simultaneously driven to the pressure reducing side to perform the drawing operation of the meniscus 93, the amount of received light is reduced, and when the meniscus 93 is separated from the waveguide 53. (When in the state of FIG. 7A), the amount of received light is the minimum. The detection signal at this time is the minimum value indicated by V4 in FIG. Thereafter, when the meniscus 93 is returned to the original position, the detection signal also returns to the value of V3.

  FIGS. 15A to 15C show examples of detection output waveforms when a defective nozzle is present in the nozzle row in the configuration shown in FIG. FIG. 15A shows a detection waveform when the meniscus 93 does not move at all. FIG. 15B shows a detection waveform when the meniscus 93 is pulled in but is not recovered. FIG. 15 (c) shows a detection waveform when it is in a retracted state and recovered.

[Modification 3]
FIG. 16 is a plan perspective view of a print head showing still another embodiment of the present invention. In FIG. 16, members that are the same as or similar to those in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted.

  In the print head 50 shown in FIG. 16, for each nozzle row, a waveguide 53 is formed along the center line of the nozzle row so as to pass through the center of all nozzles constituting the nozzle row. That is, the nozzles 51 are formed side by side on the waveguide 53 embedded in the nozzle plate 52. A light source 54 is disposed at one end of a waveguide 53 that is linearly formed by connecting the nozzles 51, and a light receiving element 56 is disposed at the other end. The width of the waveguide 53 is smaller than the diameter of the nozzle 51, and the movement of the meniscus 93 is detected using light absorption by the ink 92 in the nozzle 51.

  The detection principle will be described with reference to FIGS.

  17A is a cross-sectional view of the nozzle portion, and FIG. 17B is a view as seen from the ejection surface side. As shown in FIG. 17A, when the meniscus 93 of the ink 92 is drawn toward the inside of the nozzle 51 and the meniscus surface is located deeper than the thickness d of the waveguide 53, the inside of the waveguide 53 is obtained. The propagating light passes through the air portion of the nozzle 51 (passes through the nozzle 51 without being absorbed by the ink 92) and proceeds to the next waveguide 53. Therefore, as shown in FIG. 17B, the light advances through the waveguide 53 while passing through the nozzle 51 without greatly losing the amount of light.

  On the other hand, as shown in FIG. 18A, light is absorbed by the ink 92 in a state where the meniscus surface is not sufficiently drawn. Therefore, the position of the meniscus surface, that is, ejection / non-ejection can be detected by detecting the difference in the amount of light with the light receiving element disposed at the end of the waveguide.

  In the case of a configuration using such light absorption, the light source color is selected according to the ink color. For example, a red (R) light source that is a cyan absorption band color is used for cyan ink, a green (G) light source is used for magenta ink, and a blue (B) light source is used for yellow ink.

  If there is even one non-ejection nozzle in the nozzle row through which the waveguide 53 penetrates, light is not transmitted, and therefore a good SN detection is possible.

  FIG. 19 shows an example of a detection output waveform (in the case of no defective nozzle) of the light receiving element 56 in the configuration of FIG. FIG. 19 shows the detected output waveform when there is no defective nozzle in the nozzle row penetrated by the common waveguide 53. That is, in the reference state in which the actuator 524 is not driven, the meniscus 93 is in a position near the nozzle surface 50A (see FIG. 8A), and the ink 92 and the waveguide 53 are in contact with each other. Absorbed by ink 92. For this reason, the detection signal has a value indicated by V5 in FIG.

  Thereafter, the amount of received light is increased by driving the actuators 524 corresponding to the respective nozzles in the nozzle row to the pressure reducing side all at once to perform the drawing operation of the meniscus 93, and when the meniscus 93 is separated from the waveguide 53 ( In the case of FIG. 7 (a)), the maximum amount of received light is obtained. The detection signal at this time is the maximum value indicated by V6 in FIG. Thereafter, when the meniscus is returned to the original position, the detection signal also returns to the value of V5.

  20A and 20B are examples of detection output waveforms when a defective nozzle exists in the nozzle row. FIG. 20A shows a detection waveform when there is a defective nozzle in which only one meniscus does not move (no pull-in) in the nozzle row. FIG. 20B shows a detection waveform when a plurality of defective nozzles exist in the nozzle row. As shown in these drawings, if one or more defective nozzles exist in the nozzle row, the light is absorbed by the ink 92 in the nozzle 51, so that the detected waveform shows a constant value V5.

  The movement of the meniscus 93 (that is, ejection / non-ejection) can be detected based on the difference between the detection waveforms shown in FIGS.

[Other variations]
In the above-described embodiment, the configuration has been described in which the operation of drawing the meniscus is performed simultaneously for all the nozzles in the nozzle row with which the waveguide is in contact, and the presence or absence of defective nozzles is detected in units of nozzle rows. Can be configured to selectively pull out a meniscus from a plurality of nozzles constituting a nozzle row and detect ejection / non-ejection in units of nozzles.

  Further, a mode in which the number of defective nozzles is determined based on the level of the detection output signal obtained from the light receiving element 56 is also possible.

  In the embodiment described above, the example in which the waveguide is formed along the longitudinal direction of the head has been described. However, the form of forming the waveguide is not limited to this when the present invention is implemented. Waveguides can be formed in various directions (head short direction, diagonal direction, etc.) along the direction of the nozzle row in accordance with the nozzle arrangement.

  Furthermore, in the practice of the present invention, the waveguide from the light source to the light receiving element does not necessarily have a straight line configuration, and a plurality of waveguides using an optical member (folding means) such as a folding mirror or a prism. May be combined. Furthermore, the number of light sources and light receiving elements does not necessarily need to match, and light emitted from one light source is branched by a beam splitter or the like to be guided to a plurality of waveguides, and each end of each waveguide is A mode in which a light receiving element is arranged is also possible.

  In the above embodiment, an inkjet recording apparatus using a page-wide full-line head having a nozzle row having a length corresponding to the entire width of the recording medium has been described. However, the scope of application of the present invention is not limited to this, and the short length The present invention can also be applied to an ink jet recording apparatus using a shuttle head that records an image while reciprocating the recording head.

  In the above description, an ink jet recording apparatus is illustrated as an example of an image forming apparatus, but the scope of application of the present invention is not limited to this. For example, the droplet discharge head of the present invention can also be applied to a photographic image forming apparatus that applies a developer without contact to photographic paper. The scope of application of the present invention is not limited to an image forming apparatus, and the present invention can be applied to various apparatuses such as a coating apparatus that applies a treatment liquid or other liquid to a medium using a droplet discharge head.

1 is an overall configuration diagram of an ink jet recording apparatus using a droplet discharge device according to an embodiment of the present invention. FIG. 1 is a plan view of a main part around a printing unit of the ink jet recording apparatus shown in FIG. Plane perspective view when the print head is viewed from the ejection surface (nozzle surface) side Sectional drawing which shows the three-dimensional structure of one discharge element in a print head FIG. 5 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. Main block diagram showing the system configuration of the inkjet recording apparatus of this example FIGS. 7A and 7B are diagrams for explaining a detection principle in the present embodiment, FIG. 7A is a cross-sectional view of a nozzle portion in a state where a meniscus is drawn, and FIG. 8A and 8B are diagrams for explaining a detection principle in the present embodiment, in which FIG. 8A is a cross-sectional view of a nozzle portion in a state where a meniscus is not drawn, and FIG. The figure which shows the example of the detection output waveform of the light receiving element when there is no defective nozzle The figure which shows the example of a detection output waveform of a light receiving element in case a defective nozzle exists A flowchart showing an operation sequence in the ink jet recording apparatus according to the present embodiment. Plane perspective view of a print head showing another embodiment of the present invention The plane perspective view of the print head which shows other embodiments of the present invention. The figure which shows the example of a detection output waveform of the light receiving element when the defective nozzle does not exist in the example shown in FIG. The figure which shows the example of a detection output waveform of a light receiving element when a defective nozzle exists in the example shown in FIG. The plane perspective view of the print head which shows other embodiments of the present invention. FIGS. 17A and 17B are diagrams for explaining the detection principle in the example shown in FIG. 16, in which FIG. 17A is a cross-sectional view of the nozzle portion in a state where the meniscus is drawn, and FIG. FIGS. 18A and 18B are diagrams for explaining the detection principle in the example shown in FIG. 16, in which FIG. 18A is a cross-sectional view of the nozzle portion in a state where the meniscus is drawn, and FIG. FIG. 16 is a diagram illustrating an example of a detection output waveform of the light receiving element when there is no defective nozzle in the example illustrated in FIG. 16. FIG. 16 is a diagram illustrating an example of a detection output waveform of the light receiving element when a defective nozzle exists in the example illustrated in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device 12 ... Printing part, 12K, 12C, 12M, 12Y ... Print head, 14 ... Ink storage / loading part, 16 ... Recording paper, 22 ... Adsorption belt conveyance part, 50 ... Print head, 51 ... Nozzle 52 ... Nozzle plate, 53A, 53B, 53 ... Waveguide, 54 ... Light source, 55 ... Lens, 56 ... Light receiving element, 57 ... Lens, 72 ... System controller, 80 ... Print controller, 84 ... Head driver, 85 ... Discharge detection control unit, 92 ... ink, 93 ... meniscus, 512 ... pressure chamber, 514 ... common flow path, 524 ... actuator

Claims (7)

A nozzle row in which a plurality of nozzles for discharging droplets are arranged;
A waveguide provided corresponding to the nozzle row and forming a part of wall surfaces of a plurality of nozzles constituting the nozzle row;
A light source for generating light to be introduced into the waveguide;
A light receiving means for receiving light propagated through the waveguide and outputting a signal corresponding to the amount of light received;
Meniscus driving means for changing the position of the meniscus with respect to the waveguide by changing the pressure of the liquid in the pressure chamber communicating with the nozzle to advance and retract the meniscus in the nozzle along the discharge direction;
Determining means for determining the presence or absence of a defective nozzle based on a signal obtained from the light receiving means as the meniscus moves by the meniscus driving means;
A droplet discharge apparatus comprising:   The first waveguide and the second waveguide are arranged on both sides of the nozzle row with the nozzle row in between, the light source is arranged at one end of the first waveguide, and the other end The light receiving element is disposed in the first waveguide, and a part of the light propagating through the first waveguide passes through the liquid in the nozzle according to the position of the meniscus and enters the second waveguide. The droplet discharge device according to claim 1, wherein the droplet discharge device is provided.   A first waveguide and a second waveguide are arranged on both sides of the nozzle row with the nozzle row interposed therebetween, the light source is arranged at an end of the first waveguide, and the second waveguide is arranged. The light receiving element is disposed at an end portion of the waveguide, and a part of the light propagating through the first waveguide passes through the liquid in the nozzle according to the position of the meniscus and enters the second waveguide. 2. The droplet discharge device according to claim 1, wherein the droplet discharge device has a structure that enters and receives light by the light receiving element through the second waveguide.   4. The liquid droplet ejection apparatus according to claim 1, further comprising a recovery unit configured to perform a recovery process on the nozzle row when it is determined by the determination unit that there is a defective nozzle. 5. .   An ink jet recording apparatus using the droplet discharge device according to claim 1, wherein the recording head includes a nozzle row in which the plurality of nozzles are arranged and the waveguide. An ink jet recording apparatus that records an image on the recording medium by ejecting ink droplets from the nozzles while relatively moving the recording medium.   6. The ink jet recording apparatus according to claim 5, wherein the presence or absence of a defective ejection nozzle is determined based on a detection signal from the light receiving means during an image recording operation on the recording medium by the recording head. In a droplet discharge head having a nozzle row in which a plurality of nozzles for discharging droplets are arranged, a waveguide that forms part of the wall surface of the plurality of nozzles constituting the nozzle row is embedded, and a light source The structure is such that the emitted light is guided into the waveguide, the light propagated in the waveguide is received by a light receiving means, and a signal corresponding to the amount of received light is obtained.
Applying a pressure change to the liquid in the pressure chamber communicating with the nozzle to advance and retract the meniscus in the nozzle along the discharge direction, and perform meniscus driving to change the position of the meniscus with respect to the waveguide,
A discharge detection method, comprising: determining whether or not there is a defective nozzle based on a signal obtained from the light receiving means as the meniscus moves by the meniscus drive.

Images