JP2011042145A - Liquid droplet delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct deviation of density highly precisely. <P>SOLUTION: When a difference between a density of a test pattern of a solid image formed by a nozzle group 78A on an inlet side and a density of a test pattern of a solid image formed by a nozzle group 78B on an outlet side, both read by an optical sensor, is at least a threshold value, the adjustment amount of a drive voltage in an electric substrate 86A on the inlet side and a magnification of the drive voltage in an electric substrate 86B on the outlet side are determined so that the densities of the test patterns of the solid images formed by the nozzle group 78A on the inlet side and the nozzle group 78B on the outlet side, respectively, become target densities. When the difference between the density of the test pattern of the solid image formed by the nozzle group 78A on the inlet side and the density of the test pattern of the solid image formed by the nozzle group 78B on the outlet side read again by the optical sensor is at least the threshold value, a liquid flow rate adjusting means 84 is controlled so as to increase a flow rate to an ink outlet passage 80B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a droplet discharge device.

  Conventionally, a plurality of nozzles for discharging functional liquid are provided, and the plurality of nozzles are divided into a plurality of groups smaller than the number of nozzles, and the discharge amount of the functional liquid discharged from the nozzles is each group. An ink jet recording apparatus controlled every time is known (Patent Document 1). In the nozzle grouping of the ink jet recording apparatus, the positions on the ink jet head where the nozzles are arranged are divided into a plurality of areas, and the nozzles belonging to each area belong to one group.

  Also, a plurality of nozzle units are divided into a recording head capable of recording the recording medium width by droplets ejected from the nozzles, and a portion where the ejection characteristics change in the nozzle arrangement of the recording heads to form a plurality of nozzle units. Drive means for driving each nozzle unit; and adjustment means provided for each of the nozzle units and for adjusting the drive by the drive means according to the average density measured in advance for each nozzle unit; An inkjet recording apparatus provided is known (Patent Document 2).

JP 2002-196127 A JP 2006-56096 A

  The present invention relates to the density of the first reference image formed by the first droplet discharge element group closer to the inlet from the outlet and the second density formed from the second droplet discharge element group closer to the outlet from the inlet. When the difference from the density of the reference image is greater than or equal to a predetermined value, the drive voltage of the first droplet discharge element group and the second droplet discharge element group is adjusted, or the flow from the inflow side to the outflow side It is an object of the present invention to provide a droplet discharge device capable of accurately correcting density unevenness as compared with a case where there is no configuration for adjusting the flow rate of the liquid flowing into the path.

  In order to achieve the above object, a droplet discharge apparatus according to the invention described in claim 1 includes a droplet discharge unit in which a plurality of droplet discharge elements for discharging droplets are arranged in a predetermined direction; An inflow side flow path and an outflow side flow path extending in a direction corresponding to a predetermined direction are connected at one end side, and liquid is stored in the other end side of each of the inflow side flow path and the outflow side flow path. The liquid reservoir is connected, and the liquid is allowed to flow from the inflow side channel to the droplet discharge means via the inflow port, and the liquid is discharged from the droplet discharge means via the outflow port. The first liquid droplets comprising the circulation path for circulating the liquid between the plurality of liquid droplet ejection elements and the liquid storage portion, and the liquid droplet ejection element closer to the inflow port than the outflow port. Driving the first droplet discharge element group by applying a drive voltage to the discharge element group A first drive control means for driving the second droplet ejection element group by applying a driving voltage to the second droplet ejection element group comprising the droplet ejection elements closer to the outlet than the inflow port. And driving the first droplet discharge element group by the first drive control means so that a reference image is formed on the recording surface by the two drive control means and the first droplet discharge element group, and the second liquid First control means for driving the second droplet discharge element group by the second drive control means so as to form a reference image on the recording surface by the droplet discharge element group, and the first droplet discharge element group A difference in density between a reading unit that reads the reference image formed on the recording surface and the reference image formed on the recording surface by the first droplet discharge element group and the reference image read by the reading unit is in advance. More than the specified value If so, an adjustment amount for determining an adjustment amount of the drive voltage in the first drive control means and an adjustment amount of the drive voltage in the second drive control means so that each density of the reference image becomes a target density. Determining means.

  According to a second aspect of the present invention, there is provided a droplet discharge device, comprising: a droplet discharge unit in which a plurality of droplet discharge elements for discharging droplets are arranged in a predetermined direction; and a direction corresponding to the predetermined direction. An inflow side flow path and an outflow side flow path that extend to one end side, and a liquid storage section that stores liquid is connected to the other end side of each of the inflow side flow path and the outflow side flow path, and By causing the liquid to flow from the inflow side channel to the droplet discharge means via the inflow port, and to allow the liquid to flow out from the droplet discharge means to the outflow side channel via the outflow port, A liquid passage for circulating the liquid between the liquid droplet discharge element and the liquid reservoir, and a first liquid droplet discharge element group configured to drive the first liquid droplet discharge element group including the liquid droplet discharge element closer to the inlet than the outlet. 1 drive control means, and the droplet discharge closer to the outlet than the inlet Second drive control means for driving a second droplet discharge element group comprising elements, liquid flow rate adjusting means for adjusting the flow rate of the liquid flowing from the inflow side flow path to the outflow side flow path, and the first droplet The first drive control means drives the first droplet discharge element group so that a reference image is formed on the recording surface by the discharge element group, and the reference image is formed on the recording surface by the second droplet discharge element group. First control means for driving the second droplet discharge element group by the second drive control means to form the reference image formed on the recording surface by the first droplet discharge element group, and When the difference in density between the reading unit that reads the reference image formed on the recording surface by the first droplet discharge element group and the reference image read by the reading unit is equal to or greater than a predetermined value, the liquid Flow rate Includes a second control means for controlling the liquid flow rate adjusting means to increase, the is configured.

  According to a third aspect of the present invention, in the liquid droplet ejection apparatus according to the first aspect of the present invention, a liquid flow rate adjusting means for adjusting a flow rate of the liquid flowing from the inflow side flow channel to the outflow side flow channel. A second control unit that controls the liquid flow rate adjusting unit to increase the liquid flow rate when the difference in density of the reference image read by the reading unit is equal to or greater than a predetermined value; Including.

  As described above, according to the droplet discharge device of the first aspect, the density of the reference image formed by the first droplet discharge element group closer to the inlet than the outlet and the closer to the outlet than the inlet. When the difference from the density of the reference image formed by the second droplet discharge element group is equal to or greater than a predetermined value, the drive voltages of the first droplet discharge element group and the second droplet discharge element group are adjusted. Compared to the case where the configuration is not provided, an effect that the density unevenness can be corrected with high accuracy is obtained.

  According to the droplet discharge device of claim 2, the density of the reference image formed by the first droplet discharge element group closer to the inlet than the outlet and the second droplet closer to the outlet from the inlet. When the difference from the density of the reference image formed by the ejection element group is not less than a predetermined value, there is no configuration for adjusting the flow rate of the liquid flowing from the inflow side flow path to the outflow side flow path. Compared to the case, there is an effect that the density unevenness can be corrected with high accuracy.

  According to the droplet discharge device of claim 3, the density of the reference image formed by the first droplet discharge element group closer to the inlet than the outlet and the second droplet closer to the outlet from the inlet. When the difference from the density of the reference image formed by the ejection element group is not less than a predetermined value, there is no configuration for adjusting the flow rate of the liquid flowing from the inflow side flow path to the outflow side flow path. Compared to the case, there is an effect that the density unevenness can be corrected with high accuracy.

1 is a schematic diagram illustrating an overall configuration of a droplet discharge device according to a first embodiment of the present invention. It is a block diagram which shows the principal part of the control system of the droplet discharge apparatus which concerns on the 1st Embodiment of this invention. FIG. 2 is a diagram illustrating a configuration of a recording head and an ink cartridge of the droplet discharge device according to the first embodiment of the present invention. It is a flowchart which shows the content of the density nonuniformity detection processing routine of the droplet discharge apparatus which concerns on the 1st Embodiment of this invention. (A) A figure showing an example of a test pattern formed by an inflow side nozzle group, and (B) a figure showing an example of a test pattern formed by an outflow side nozzle group. It is a figure which shows a reference | standard drive waveform. (A) The figure which shows an example of the test pattern for every magnification of the drive voltage formed by the inflow side nozzle group, (B) An example of the test pattern for every magnification of the drive voltage formed by the outflow side nozzle group FIG. It is a figure which shows a mode that a voltage magnification is adjusted with respect to a reference | standard drive waveform. It is a graph which shows the relationship between the magnification of a drive voltage, and the density | concentration of a test pattern.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a case where the droplet discharge device of the present invention is applied to an ink jet type droplet discharge device will be described.

  FIG. 1 is a schematic diagram showing the overall configuration of an ink jet type droplet discharge apparatus 10 according to a first embodiment.

  The droplet discharge device 10 includes a recording head array 12. The recording head array 12 includes a cyan ink liquid (C), a magenta ink liquid (M), a yellow ink liquid (Y), a black ink liquid (K), and a processing liquid (T). Correspondingly, five recording heads 14C, 14M, 14Y, 14K, and 14T are provided.

  The recording heads 14 </ b> C, 14 </ b> M, 14 </ b> Y, 14 </ b> K, and 14 </ b> T are long recording heads called FWA (Full Width Array) whose width is substantially equal to the width of the recording paper 16. The recording heads 14 </ b> C, 14 </ b> M, 14 </ b> Y, 14 </ b> K, and 14 </ b> T are fixed, and eject the respective ink droplets and processing droplets from the ejection nozzles onto the recording paper 16 that is being conveyed. An image is formed based on the data. The treatment liquid is colorless or light-colored, and the ink liquid of each color is dropped on the recording paper 16 and then dropped so as to overlap, thereby reducing ink bleeding and improving the image quality.

  The recording heads 14C, 14M, 14Y, 14K, and 14T are connected to ink cartridges 18C, 18M, 18Y, 18K, and 18T, which store CMYK ink liquids and processing liquids, respectively, through ink inflow paths and ink outflow paths described later. The ink liquid and the processing liquid are supplied to the recording heads 14C, 14M, 14Y, 14K, and 14T. As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink are used.

  In addition, the droplet discharge device 10 includes a conveyance belt 19 that is an endless belt below the recording head array 12. The conveyor belt 19 is wound around the drive rolls 20A and 20B, and is driven to rotate in the A direction, which is the clockwise direction in FIG. 1, by the rotational force of the drive rolls 20A and 20B. The conveying belt 19 when facing the recording head array 12 is flat, and the recording paper 16 is conveyed to the flat area, and ink droplets are applied to the recording paper 16 from the recording heads 14C, 14M, 14Y, and 14K. As a result, an image is formed. At this time, the recording heads 14C, 14M, 14Y, and 14K discharge ink droplets from the discharge nozzles to the recording paper 16 with a time difference. As a result, the ink droplets of the respective colors are superimposed on the recording paper 16, and an image is formed.

  Further, the droplet discharge device 10 includes a charging roll 22 on the upstream side in the driving direction from the region of the conveying belt 19 facing the recording head array 12. A predetermined voltage is applied to the charging roll 22, and the charging roll 22 is driven while sandwiching the conveyance belt 19 and the recording paper 16 with the drive roll 20 </ b> A, thereby applying a charge to the recording paper 16. The recording paper 16 that has been charged by the charging roll 22 is electrostatically attracted to the transport belt 19 and is transported along with the circumferential drive of the transport belt 19.

  The recording paper 16 is accumulated in a paper feed tray 24 provided on the lower side inside the droplet discharge device 10. The recording paper 16 is taken out from the paper feed tray 24 one by one by the pick-up roll 26, and is transported to the transport belt 19 by the recording paper transport unit 30 having a plurality of transport rollers 28.

  A peeling plate 32 is disposed on the downstream side in the driving direction of the conveying belt 19 in FIG. 1 from the portion facing the recording head array 12. The peeling plate 32 peels the recording paper 16 from the transport belt 19. The recording paper 16 peeled off from the transport belt 19 is transported by a plurality of discharge rollers 36 constituting a discharge transport section 34 and is discharged to a paper discharge tray 38 provided at the upper part of the droplet discharge device 10.

  A cleaning roll 40 that sandwiches the conveyance belt 19 with the drive roll 20B is disposed on the downstream side in the rotation direction of the conveyance belt 19 in FIG. The cleaning roll 40 cleans the surface of the conveyor belt 19.

  Further, the recording paper 16 having an image formed on one side is conveyed again to the conveyance belt 19 by the reverse conveyance unit 44 constituted by a plurality of reverse rollers 42, and an image is formed on the other side. The reverse conveying unit 44 branches from the discharge conveying unit 34 and is arranged to convey the recording paper 16 to the recording paper conveying unit 30.

  An optical sensor 46 is disposed on the upstream side in the rotational direction from the position where the peeling plate 32 is disposed on the downstream side in the rotational direction of the conveyor belt 19 in FIG. 1 with respect to the portion facing the recording head array 12. The optical sensor 46 is composed of, for example, a CCD line sensor or a CCD area sensor, and reads, for example, a test pattern image for correcting the density of ink ejected by the ejection nozzle at a predetermined reading resolution.

  FIG. 2 is a diagram illustrating a main part of a control system of the droplet discharge device 10.

  The droplet discharge device 10 includes a CPU 50 that controls the entire droplet discharge device 10. The CPU 50 includes a ROM 52, a RAM 54, a hard disk storage device 56, an image data input unit 58, an operation display unit 60, an image formation control unit 62, an image data processing unit 64, an optical sensor 46, a control bus, a data bus, and the like. Connection is made via a bus 66.

  The ROM 52 stores a control program for controlling the droplet discharge device 10. The RAM 54 is used as a work space for processing various data. The hard disk storage device 56 stores image data, test pattern data for forming a test pattern image, various data relating to image formation, and the like. Further, the hard disk storage device 56 stores nozzle characteristic data (such as a correction LUT described later) for each ejection nozzle and drive voltage magnification data for each module.

  The image data input unit 58 receives image data input from a personal computer (not shown). The input image data is transmitted to the hard disk storage device 56.

  The operation display unit 60 includes an operation button for a user to perform various operations in addition to a touch panel in which an operation function and a display function are integrated. The operation display unit 60 receives an operation such as start of image formation on the recording paper 16 and notifies the user of the control state of the droplet discharge device 10 and the like.

  The image forming control unit 62 drives the recording heads 14C, 14M, 14Y, 14K, and 14T and drives various roll motors (not shown) to form an image on the recording paper 16 based on the image data. Control.

  The image data processing unit 64 performs image processing such as ink density adjustment on the image data stored in the hard disk storage device 56. The image data processing unit 64 processes read data obtained by reading the test pattern with the optical sensor 46 and corrects the ink density of the image formed on the recording paper 16. A table (hereinafter referred to as “correction LUT”) is generated.

  Next, the detailed configuration of the recording heads 14C, 14M, 14Y, 14K, and 14T will be described. Since each of the recording heads 14C, 14M, 14Y, 14K, and 14T used in the present embodiment has the same configuration, a detailed configuration of one recording head 14 will be described below.

  As shown in FIG. 3, the recording head 14 includes a plurality of ejection nozzles 70 arranged in the width direction of the recording paper 16 (direction intersecting the conveyance direction of the recording paper 16) for each predetermined number of ejection nozzles 70. A plurality of modules 72 divided into two are arranged in the width direction of the recording paper 16. Each module 72 is formed with an ink inlet 74A and an ink outlet 74B. Each module 72 includes an ink chamber 76A on the ink inlet 74A side and an ink chamber 76B on the ink outlet 74B side, and the ink chambers 76A and 76B are connected by a connection path 77. The plurality of ejection nozzles 70 belonging to the module 72 includes an inlet-side nozzle group 78A composed of ejection nozzles 70 to which ink liquid is supplied from an ink chamber 76A on the ink inlet 74A side, and an ink chamber 76B on the ink outlet 74B side. It is divided into an outlet side nozzle group 78B composed of discharge nozzles 70 to which ink liquid is supplied. The plurality of discharge nozzles 70 are arranged in the width direction of the recording paper 16, and are alternately arranged so as to belong to the inlet-side nozzle group 78A and the outlet-side nozzle group 78B in the order arranged in the width direction of the recording paper 16. It is distributed to.

  Further, an ink inflow passage 80A and an ink outflow passage 80B extending in the width direction of the recording paper 16 are provided, and the ink inflow passage 80A and the ink outflow passage 80B are arranged in parallel with the plurality of modules 72 arranged. One end of each of the ink inflow path 80A and the ink outflow path 80B is connected to the corresponding ink cartridge 18, and a pump 81 is provided in the middle of the ink inflow path 80A.

  The ink inflow passage 80A is connected to the ink chamber 76A on the ink inflow port 74A side of each module 72 via the valve 82A and the ink inflow port 74A, and the ink outflow passage 80B is connected to the valve 82B and the ink outflow port. Each module 72 is connected to an ink chamber 76B on the ink outlet 74B side via 74B.

  Focusing on one module 72, the ink liquid flows from the ink inlet 74A side in the vicinity of the ejection nozzle 70 in the ink chamber 76A and flows out to the ink outlet 74B side, and the ink inflow path 80A and the ink outflow path 80B. , The ink liquid circulates between the discharge nozzle 70 and the ink cartridge 18. Thus, the ink liquid circulation path is formed by the ink inflow path 80A and the ink outflow path 80B.

  The other ends of the ink inflow path 80A and the ink outflow path 80B are connected to each other, and a flow rate adjusting means 84 configured by, for example, an open / close valve is provided at a connection portion between the other ends of the ink inflow path 80A and the ink outflow path 80B. ing.

  The ink liquid that has entered the module 72 from the ink inflow path 80A flows directly into the ink outflow path 80B through each module 72 and the ink inflow path 80A. There are two routes with the flow entering the ink outflow path 80B.

  Further, the back pressure (circulation differential pressure) on the ink inflow side and the ink outflow side is adjusted by a back pressure adjusting mechanism (not shown), and the difference in pressure applied to the ink inflow side and the ink outflow side for creating a circulation flow is Has occurred.

  On the ink inlet 74A side outside the module 72, an inlet side that generates a signal to be applied to each drive element (not shown) for driving each discharge nozzle 70 of the inlet-side nozzle group 78A of the module 72. An electric substrate 86A is provided. Further, on the ink outlet 74B side outside the module 72, a flow for generating a signal to be applied to each driving element (not shown) for driving each discharge nozzle 70 of the outlet side nozzle group 78B of the module 72 is shown. An outlet side electric board 86B is provided. The inlet side electric board 86 </ b> A and the outlet side electric board 86 </ b> B are provided for each module 72.

  The inlet-side electric board 86A generates and applies a signal representing a drive voltage to be applied to each drive element for each discharge nozzle 70 of the inlet-side nozzle group 78A of the module 72 in accordance with control by the image formation control unit 62. . In addition, the outlet-side electric board 86B generates a signal representing a driving voltage to be applied to each driving element for each discharge nozzle 70 of the outlet-side nozzle group 78B of the module 72, under the control of the image forming control unit 62, Apply.

  The driving element of this embodiment is a piezo element. When a driving voltage is applied to the driving element, the driving element vibrates, the diaphragm vibrates, and the pressure generating chamber expands or contracts. As the volume of the pressure generating chamber changes (the pressure changes) due to the expansion and contraction, the ink liquid filled therein is discharged from the discharge nozzle 70.

  Next, the density unevenness detection processing routine in the first embodiment will be described with reference to FIG. When an instruction signal for instructing density unevenness correction is input, the CPU 50 executes the density unevenness correction program stored in the ROM 52, whereby this routine is started for each ink color of cyan, magenta, yellow, and black. . In the following, a case where density unevenness correction is performed for cyan (C) will be described.

  First, in step 100, all the discharge nozzles 70 of the inlet side nozzle group 78A are driven for each module 72 by the recording head 14C, the image formation control unit 62, and the inlet side electric substrate 86A, and ink droplets are discharged. 5 is ejected to form a test pattern 90 composed of a solid image shown in FIG.

  At this time, the drive voltage of the reference discharge energy (for example, the drive waveform in FIG. 6; hereinafter referred to as “reference waveform”) is applied only to the drive element corresponding to the discharge nozzle 70 of the inlet side nozzle group 78A. Note that since the inlet nozzle group 78A and the outlet nozzle group 78B are combined to form the number of nozzles of the entire module 72, the duty of the solid image of the test pattern 90 is half or less of the total nozzle density.

  Further, the recording head 14C, the image formation control unit 62, and the outlet-side electric substrate 86B drive all the discharge nozzles 70 of the outlet-side nozzle group 78B for each module 72 to discharge ink droplets. Then, a test pattern 92 composed of a solid image shown in FIG. 5B is formed on the recording paper 16. At this time, similarly to the discharge nozzles 70 of the inlet side nozzle group 78A, the reference waveform is also given to the drive elements corresponding to the discharge nozzles 70 of the outlet side nozzle group 78B.

  In step 102, when the recording paper 16 on which the test patterns 90 and 92 are formed is conveyed to the reading position of the optical sensor 46, the test pattern 90 and the test pattern 90 formed on the recording paper 16 by the optical sensor 46. An image is read from the entire surface of 92, and read data based on the test patterns 90 and 92 is output.

  In the next step 104, the density of the test pattern 90 and the density of the test pattern 92 for each module 72 are obtained from the read data based on the test patterns 90 and 92 obtained in step 102, and at least one module 72 is obtained. Then, it is determined whether the density difference between the test patterns 90 and 92 is equal to or greater than a threshold value. For all the modules 72, when the difference in density between the test patterns 90 and 92 is less than the threshold value, it is determined that density unevenness correction between the inlet side and the outlet side is not necessary, and the process proceeds to Step 120 described later. To do. On the other hand, if the density difference between the test patterns 90 and 92 is greater than or equal to the threshold value for at least one module 72, in step 106, the flow rate adjusting means 84 is controlled so as to increase the flow rate. As a result, the flow rate of ink flowing from the ink inflow path 80A to the ink outflow path 80B increases, so that the ink liquid in the ink inflow path 80A and the ink outflow path 80B is homogenized, and the air bubbles remaining in the ink liquid circulation path Becomes easier to be pushed out.

  When the state in which the ink flow rate is increased continues for a predetermined time, the flow rate adjusting means 84 is controlled to restore the increased flow rate.

  In step 108, as in step 100 above, the discharge nozzle 70 of the inlet side nozzle group 78A is driven for each module 72 by the recording head 14C, the image formation control unit 62, and the inlet side electric substrate 86A. Then, the ink liquid is discharged to form the test pattern 90 on the recording paper 16. In addition, the recording head 14C, the image formation control unit 62, and the outlet-side electric substrate 86B drive the ejection nozzles 70 of the outlet-side nozzle group 78B for each module 72 to eject ink liquid, thereby causing a test pattern. 92 is formed on the recording paper 16.

  In step 110, as in step 102, when the recording paper 16 on which the test patterns 90 and 92 are formed is conveyed to the reading position of the optical sensor 46, the optical sensor 46 applies the recording paper 16 to the recording paper 16. An image is read from the entire surface of the formed test patterns 90 and 92, and read data based on the test patterns 90 and 92 is output.

  In the next step 112, as in step 104, the density of the test pattern 90 and the density of the test pattern 92 are obtained from the read data based on the test patterns 90 and 92 obtained in step 110, and at least 1 is obtained. It is determined whether or not the density difference between the test patterns 90 and 92 is greater than or equal to a threshold value for the two modules 72. For all the modules 72, when the difference in density between the test patterns 90 and 92 is less than the threshold value, it is determined that density unevenness correction between the inlet side and the outlet side is not necessary, and the process proceeds to Step 120 described later. To do. On the other hand, if the density difference between the test patterns 90 and 92 is greater than or equal to the threshold for at least one module 72, in step 114, the recording head 14C, the image formation control unit 62, and the inlet-side electric substrate 86A For the module 72, the drive elements corresponding to all the discharge nozzles 70 of the inlet side nozzle group 78A are driven at different magnifications of the drive voltage to discharge ink droplets, as shown in FIG. A test pattern 94 composed of a solid image for each drive voltage magnification is formed on the recording paper 16. At this time, as shown in FIG. 8, the discharge energy used as a reference is increased or decreased stepwise with respect to the reference (the voltage magnification of the drive waveform is increased or decreased) to correspond to the discharge nozzle 70 of the inlet side nozzle group 78A. It is given only to the driving element to be used. Since the inlet nozzle group 78A and the outlet nozzle group 78B are combined to form the number of nozzles of the entire module 72, the duty of the solid image of the test pattern 94 is half or less of the total nozzle density.

  Further, the drive elements corresponding to all the discharge nozzles 70 of the outlet-side nozzle group 78B for each module 72 are changed by the recording head 14C, the image formation control unit 62, and the outlet-side electric substrate 86B. In this manner, the ink droplets are ejected to form a test pattern 96 composed of a solid image for each drive voltage magnification shown in FIG. At this time, similarly to the discharge nozzle 70 of the inlet-side nozzle group 78A, the reference discharge energy is stepwise with respect to the reference for the drive elements corresponding to the discharge nozzle 70 of the outlet-side nozzle group 78B. Increase / decrease (increase / decrease voltage magnification of drive waveform).

  In step 116, when the recording paper 16 on which the test patterns 94 and 96 for each magnification of the driving voltage are conveyed to the reading position of the optical sensor 46, the optical sensor 46 forms the recording paper 16 on the recording paper 16. An image is read from the entire surface of the test patterns 94 and 96 for each of the drive voltage magnifications, and read data based on the test patterns 94 and 96 is output.

  In step 118, the density of the test pattern 94 and the density of the test pattern 96 for each drive voltage magnification are determined for each module 72 from the read data based on the test patterns 94 and 96 obtained in step 116. For each module 72, the relationship between the drive voltage magnification shown in FIG. 9 and the density of each of the test patterns 94 and 96 is obtained. Further, for each module 72, in order to obtain a target concentration for the inlet side nozzle group 78A and the outlet side nozzle group 78B, from the relationship between the magnification of the driving voltage and the density of each of the test patterns 94 and 96. The drive voltage magnification is determined.

  For example, when the preset target concentration is 140, the voltage magnification for obtaining the target concentration 140 on both the inlet side and the outlet side is determined to be 0.35 and 1.00 (FIG. 9). reference).

  Drive voltage magnification data representing the magnification of the drive voltage determined for the inlet side nozzle group 78A and the outlet side nozzle group 78B of each module 72 is generated, and the generated drive voltage magnification data is transferred to the hard disk storage device 56. And memorized.

  In the next step 120, a test pattern composed of a plurality of density patterns is formed on the recording paper 16 by the recording head 14 </ b> C and the image formation control unit 62. At this time, the image formation control unit 62 uses the drive voltage magnification determined in step 118 to drive each drive element of the discharge nozzle 70 of the inlet side nozzle group 78A of the recording head 14C and the outlet side nozzle group. Each drive element of the discharge nozzle 70 of 78B is driven.

  In step 122, when the recording paper 16 on which the test pattern composed of a plurality of density patterns has been conveyed to the reading position of the optical sensor 46, the test formed on the recording paper 16 by the optical sensor 46. An image is read from the entire surface of the pattern, and read data based on the test pattern is output.

  In the next step 124, the output density at the position of each discharge nozzle is obtained for each density pattern from the read data based on the test pattern obtained in step 122, and the output density of each discharge nozzle becomes the target density. Thus, the correction amount of the cyan input density value of each discharge nozzle is calculated. Further, based on the correction amount of the cyan input density value of each discharge nozzle for each density value of the density pattern, a correction LUT is generated so that the output density at the position of each discharge nozzle approaches the target density, and step At 126, the generated correction LUT is transferred to and stored in the hard disk storage device 56, and the density unevenness detection processing routine ends.

  The above-described density unevenness detection processing routine is similarly executed for magenta, yellow, and black ink colors.

  When the droplet discharge device 10 receives input of image data from a personal computer or the like, the droplet discharge device 10 is temporarily stored in the hard disk storage device 56, and the image data is read from the hard disk storage device 56. Then, the input pixel value of the image data is converted into a converted pixel value by the correction LUT stored in the hard disk storage device 56, and the image data is corrected. The recording heads 14C and 14M are based on the corrected image data using the drive voltage magnification determined for each module 72 for each ink color represented by the drive voltage magnification data stored in the hard disk storage device 56. , 14Y, 14K, and 14T are driven, and an image based on the image data is formed on the recording paper 16.

  In the above embodiment, the case where the density unevenness detection processing routine is executed when the instruction signal instructing the density unevenness correction is input has been described as an example. However, the present invention is not limited to this. For example, a solid image test pattern is formed on a recording sheet during printing processing or between printing processing, and flow adjustment to correct density unevenness when printing processing is not performed Alternatively, the magnification of the drive voltage may be adjusted.

  Next, a second embodiment will be described. In addition, about the part which becomes the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the second embodiment, a case where the liquid droplet ejection apparatus of the present invention is applied to a recording head inspection apparatus that inspects a recording head will be described.

  The recording head inspection apparatus according to the second embodiment stores a recording head 14 to be inspected (for example, a recording head 14C corresponding to cyan ink liquid) and an ink cartridge 18 (for example, cyan ink liquid). Ink cartridge 18C) is attached. The recording head 14 and the ink cartridge 18 are connected by an ink inflow path 80A and an ink outflow path 80B as in the first embodiment.

  The recording head inspection apparatus includes a CPU 50, and the CPU 50 includes a ROM 52, a RAM 54, a hard disk storage device 56, an operation display unit 60, an image formation control unit 62, an image data processing unit 64, and an optical sensor 46.

  The image formation control unit 62 controls driving of the recording head 14 to be inspected in order to form an image on the recording paper 16 based on the image data of the test pattern.

  The image data processing unit 64 processes read data obtained by reading the test pattern with the optical sensor 46, and for each module 72, the magnification of the drive voltage for the inlet side nozzle group 78A and the outlet side nozzle group 78B. To decide.

  Next, the operation of the recording head inspection apparatus according to the second embodiment will be described. First, when the recording head 14 and the ink cartridge 18 to be inspected are attached and an instruction signal instructing inspection is input, the CPU 50 executes the inspection program stored in the ROM 52, whereby the first embodiment described above. A routine similar to Step 100 to Step 118 of the density unevenness detection processing routine described in the above is executed.

  As a result, when the density difference between the test patterns 90 and 92 for the at least one module 72 is greater than or equal to the threshold value, the flow rate adjusting means 84 adjusts the flow rate to increase. Further, for each module 72 of the recording head 14 to be inspected, the magnification of the drive voltage for the inlet side nozzle group 78A and the outlet side nozzle group 78B is obtained.

  Drive voltage magnification data representing the determined drive voltage magnification is registered in the image forming control unit 62 of the droplet discharge device 10 in which the inspected recording head 14 and ink cartridge 18 are incorporated.

  For each ink color C, M, Y, K, the recording head 14 and the ink cartridge 18 are inspected as described above.

  When the inspected recording heads 14C, 14M, 14Y, and 14K and the ink cartridges 18C, 18M, 18Y, and 18K incorporate the image data input from a personal computer or the like, the droplet discharge device 10 temporarily stores the data in the hard disk storage device 56. Then, image data is read from the hard disk storage device 56. Then, based on the read image data, the recording heads 14C, 14M, 14Y, 14K, and 14T are driven using the registered drive voltage magnification, and an image based on the image data is formed on the recording paper 16. Is done.

  In the first to second embodiments, the case where the ink chamber is divided into the outlet side and the inlet side has been described as an example. However, the present invention is not limited to this. The ink chamber may not be divided into an outlet side and an inlet side. Also in this case, the discharge nozzle group on the inlet side closer to the inlet than the outlet is referred to as the inlet-side discharge nozzle group, and the discharge nozzle group closer to the outlet from the inlet is referred to as the outlet-side discharge nozzle. A group may be used.

  Further, the case where the ink inflow path and the ink outflow path extend in the arrangement direction of the recording head modules (the width direction of the recording paper) has been described as an example, but the present invention is not limited to this, and the arranged modules For example, the ink inflow path and the ink outflow path may be provided to extend in a direction substantially parallel to the width direction of the recording paper. .

  Further, in the case where the density difference of the test pattern is equal to or greater than the threshold value, the case where the increase adjustment of the flow rate to the ink outflow path and the magnification adjustment of the drive voltage are performed has been described as an example. If the density difference of the test pattern is equal to or greater than the threshold value, the adjustment of the flow rate to the ink outflow path may be performed without adjusting the magnification of the drive voltage, and the density difference of the test pattern is equal to or greater than the threshold value. In this case, only the magnification adjustment of the drive voltage may be performed without adjusting the increase in the flow rate to the ink outflow path.

  In addition, after determining the threshold value of the density difference of the test pattern and adjusting the increase in the flow rate to the ink outflow path, the threshold value of the density difference of the test pattern is determined again to adjust the drive voltage magnification. Although described as an example, the present invention is not limited to this, and after performing the threshold determination of the density difference of the test pattern and adjusting the magnification of the driving voltage, the threshold determination of the density difference of the test pattern is performed again, You may make it perform the increase adjustment of the flow volume to an ink outflow path.

  Further, although the case where the drive element provided in each discharge nozzle of the recording head is a piezo element has been described as an example, the present invention is not limited to this and may be a heating element.

  Further, the case where the droplet discharge device forms an image (including characters) on the recording paper has been described as an example, but the recording medium is not limited to the recording paper, and the liquid to be discharged is ink. The present invention is not limited to the liquid, and may be applied to other liquid droplet ejection recording apparatuses such as a pattern forming apparatus that ejects liquid droplets onto a sheet-like substrate for pattern formation such as a semiconductor or a liquid crystal display. Good.

DESCRIPTION OF SYMBOLS 10 Droplet discharge device 12 Recording head array 14, 14C, 14M, 14Y, 14K, 14T Recording head 16 Recording paper 18, 18C, 18M, 18Y, 18K, 18T Ink cartridge 46 Optical sensor 56 Hard disk storage device 62 Image formation control part 64 Image data processing unit 70 Discharge nozzle 72 Module 74A Ink inlet 74B Ink outlet 76A, 76B Ink chamber 78A Inlet side nozzle group 78B Outlet side nozzle group 80A Ink inflow path 80B Ink outflow path 84 Flow rate adjusting means 86A Inlet Side electric board 86B Outlet side electric board 90, 92, 94, 96 Test pattern

Claims (3)

A droplet discharge means in which a plurality of droplet discharge elements for discharging droplets are arranged in a predetermined direction;
An inflow side flow path and an outflow side flow path extending in a direction corresponding to the predetermined direction are connected at one end side, and a liquid is supplied to the other end side of each of the inflow side flow path and the outflow side flow path. The liquid storage unit is connected, and the liquid is allowed to flow from the inflow side flow path to the droplet discharge means via the inlet, and the liquid is discharged from the droplet discharge means via the outlet. A circulation path for circulating a liquid between the plurality of droplet discharge elements and the liquid storage section by flowing out into the flow path;
First drive control means for driving the first droplet discharge element group by applying a drive voltage to the first droplet discharge element group composed of the droplet discharge elements closer to the inlet than the outlet;
Second drive control means for driving the second droplet discharge element group by applying a drive voltage to a second droplet discharge element group composed of the droplet discharge elements close to the outlet from the inlet;
The first liquid droplet ejection element group is driven by the first drive control means so that a reference image is formed on the recording surface by the first liquid droplet ejection element group, and recording is performed by the second liquid droplet ejection element group. First control means for driving the second droplet discharge element group by the second drive control means so as to form a reference image on a surface;
Reading means for reading the reference image formed on the recording surface by the first droplet discharge element group and the reference image formed on the recording surface by the first droplet discharge element group;
When the difference in the density of the reference image read by the reading means is greater than or equal to a predetermined value, the drive voltage is adjusted in the first drive control means so that the density of each of the reference images becomes a target density. An adjustment amount determining means for determining an amount and an adjustment amount of the drive voltage in the second drive control means;
A liquid droplet ejection apparatus including: A droplet discharge means in which a plurality of droplet discharge elements for discharging droplets are arranged in a predetermined direction;
An inflow side flow path and an outflow side flow path extending in a direction corresponding to the predetermined direction are connected at one end side, and a liquid is supplied to the other end side of each of the inflow side flow path and the outflow side flow path. The liquid storage unit is connected, and the liquid is allowed to flow from the inflow side flow path to the droplet discharge means via the inlet, and the liquid is discharged from the droplet discharge means via the outlet. A circulation path that circulates the liquid between the plurality of droplet discharge elements and the liquid storage section by flowing out into the flow path;
First drive control means for driving a first droplet discharge element group composed of the droplet discharge elements closer to the inlet than the outlet;
A second drive control means for driving a second droplet discharge element group composed of the droplet discharge elements closer to the outlet from the inlet;
Liquid flow rate adjusting means for adjusting the flow rate of the liquid flowing from the inflow side flow channel to the outflow side flow channel;
The first liquid droplet ejection element group is driven by the first drive control means so that a reference image is formed on the recording surface by the first liquid droplet ejection element group, and recording is performed by the second liquid droplet ejection element group. First control means for driving the second droplet discharge element group by the second drive control means so as to form a reference image on a surface;
Reading means for reading the reference image formed on the recording surface by the first droplet discharge element group and the reference image formed on the recording surface by the first droplet discharge element group;
A second control unit that controls the liquid flow rate adjusting unit to increase the flow rate of the liquid when the difference in density of the reference image read by the reading unit is equal to or greater than a predetermined value;
A liquid droplet ejection apparatus including: Liquid flow rate adjusting means for adjusting the flow rate of the liquid flowing from the inflow side flow channel to the outflow side flow channel;
And a second control unit that controls the liquid flow rate adjusting unit to increase the liquid flow rate when the difference in density of the reference image read by the reading unit is equal to or greater than a predetermined value. The droplet discharge device according to claim 1.

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