JP2016203463A - Droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet discharge device capable of suppressing occurrence of down time when a discharge section cannot discharge droplets by execution of maintenance for recovering a discharge failure of the discharge section.SOLUTION: A printer (droplet discharge device) comprises: discharge sections having driving elements; a detection section outputting a detection signal POUT1 (first signal or second signal) corresponding to vibration generated by driving the driving elements; a first control section causing maintenance to be executed because a discharge failure occurs in the discharge sections when the first signal is input and, on the other hand, causing the maintenance not to be executed because the discharge failure does not occur in the discharge sections when the second signal is input; and a second control section capable of outputting the second signal as a control signal POUT2. Further, the first control section causes the maintenance of the discharge sections not to be executed when the second signal is input from the second control section.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a droplet discharge device such as an ink jet printer.

  2. Description of the Related Art Conventionally, as an example of a droplet discharge device, an ink jet printer that includes a discharge unit that discharges ink (liquid) from a nozzle toward a medium by driving a drive element is known. Some of these printers detect vibrations that occur in the ejection unit by driving the drive element, and determine whether or not ejection failure has occurred due to liquid thickening or bubbles in the ejection unit. There is what is inspected (for example, Patent Document 1). In such a printer, when an ejection failure has occurred as a result of the inspection, maintenance is performed to recover the ejection failure.

JP 2013-958 A

  However, in the printer as described above, when a discharge failure occurs in the discharge unit, maintenance for the discharge unit is executed, and thus a period during which printing cannot be performed, that is, downtime occurs. For this reason, in the printer as described above, there remains room for improvement for users who place more importance on reducing the printing time than on the printing quality.

  Note that the above situation is not limited to ink jet printers, and is a problem that is generally common to droplet discharge apparatuses that perform maintenance on the discharge unit according to the state of the discharge unit that discharges droplets onto a medium. Yes.

  The present invention has been made in view of the above circumstances. An object of the present invention is to provide a droplet discharge device capable of suppressing the occurrence of downtime in which the discharge unit cannot discharge droplets by performing maintenance of the discharge unit.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A droplet discharge device that solves the above problem is based on a discharge unit having a drive element that is driven to discharge a droplet toward a medium, and vibration generated in the discharge unit by driving the drive element. A detection unit that outputs a detection signal, a maintenance unit that performs maintenance for discharging the liquid from the discharge unit, and a discharge unit that can determine that a discharge failure has occurred in the discharge unit based on the detection signal. A first control unit that causes the maintenance of the discharge unit to not be executed when it can be determined that no discharge failure has occurred in the discharge unit. Then, while the first control unit uses the detection signal when it is determined that a discharge failure has occurred in the discharge unit as the first signal, the detection when it is determined that no discharge failure has occurred When the signal is a second signal, the signal processing apparatus further includes a second control unit capable of outputting the second signal, and the first control unit receives the second signal from the second control unit. If it is, the maintenance of the discharge unit is not performed.

  According to the above configuration, when the second signal is input from the second control unit to the first control unit, even if the detection unit outputs the first signal, maintenance of the discharge unit is performed. Is not executed. Therefore, according to this configuration, it is possible to reduce downtime during which the discharge unit cannot discharge droplets.

  In the droplet discharge device, the first control unit receives the second signal from the second control unit while the discharge unit is discharging droplets toward the medium. In this case, it is preferable that the maintenance of the ejection unit is performed after the ejection of the liquid droplets to the medium is completed.

  According to the above configuration, when the discharge unit does not perform maintenance on the discharge unit while discharging the droplet toward the medium, the discharge unit finishes discharging the droplet toward the medium. After that, maintenance of the discharge unit is performed. For this reason, according to this configuration, it is possible to suppress the occurrence of a downtime and to prevent the state in which the discharge failure of the droplets has occurred in the discharge unit from continuing.

In the droplet discharge device, it is preferable that the second control unit can select whether or not to output the second signal.
According to the above configuration, by setting whether or not to output the second signal, it is possible to select whether or not maintenance is performed when the detection unit outputs the first signal. In other words, the user of the droplet discharge device can select whether to give priority to reducing the downtime or to suppress the discharge failure of the droplet in the discharge unit.

  The liquid droplet ejection apparatus further includes a housing that houses at least the ejection section, and the housing includes a window portion that exposes the medium from which liquid droplets are ejected to the ejection section to the outside of the housing. It is desirable to be provided.

  According to the above configuration, the user of the droplet discharge device can determine whether or not the maintenance of the discharge unit is necessary by visually checking the medium on which the droplet is discharged through the window portion. Therefore, the second control unit outputs the second signal, so that even when maintenance is not performed, the user can perform maintenance at an appropriate timing.

The droplet discharge device preferably further includes an illumination unit that illuminates the medium on which the droplet is discharged to the discharge unit.
According to the above configuration, the illumination unit illuminates the medium on which the droplets are ejected, so that the user of the droplet ejection device can easily see the medium on which the droplets are ejected. Therefore, the user can easily determine whether maintenance is necessary.

FIG. 2 is a perspective view illustrating a schematic configuration of a printer. The bottom view which shows the formation aspect of the nozzle in a discharge head. Sectional drawing of an ejection head. FIG. 3 is a block diagram illustrating an electrical configuration of the printer. (A)-(h) is a timing chart which shows an example of the various signals in a control part and a printing part. The graph which shows an example of the change of the electrical signal according to a residual vibration. The flowchart which shows the process routine which a 1st control part performs in order to perform printing. The flowchart which shows the process routine which a 1st control part performs in order to test | inspect whether the discharge defect has arisen in the discharge part. The flowchart which shows the process routine which a 1st control part performs in order to determine the state of a discharge part according to the period of a residual vibration. The flowchart which shows the process routine which a 2nd control part performs when test | inspecting whether the discharge defect has arisen in the discharge part.

  Hereinafter, an embodiment in which a droplet discharge device is embodied in a printing device will be described with reference to the drawings. The printing apparatus is an ink jet printer that forms characters and images by ejecting ink as an example of liquid onto a medium M such as paper.

  As illustrated in FIG. 1, the printing apparatus 10 includes a first control unit 100, a second control unit 110, a user interface 121, a communication interface 122, and a printing unit 200.

  The user interface 121 of the printing apparatus 10 includes a display and operation buttons, and exchanges information with the user of the printing apparatus 10. The communication interface 122 exchanges information with external devices such as a personal computer, a digital still camera, and a memory card that can be electrically connected to the printing apparatus 10.

  The first control unit 100 of the printing apparatus 10 controls each unit of the printing apparatus 10. For example, the first control unit 100 performs control to eject ink droplets from the printing unit 200 based on data input via the communication interface 122 while relatively moving the printing unit 200 and the medium M. . As a result, printing on the medium M is realized. On the other hand, the second control unit 110 controls a part of the printing apparatus 10 including the first control unit 100.

  In the present embodiment, the first control unit 100 and the second control unit 110 are devices including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. In addition, various functions by the first control unit 100 and the second control unit 110 are realized by the CPU operating based on a computer program. Note that at least some of the functions of the first control unit 100 and the second control unit 110 are based on the circuit configuration of the electric circuits included in the first control unit 100 and the second control unit 110. It may be realized by.

  As shown in FIG. 1, the printing unit 200 includes a carriage 210, a liquid storage unit 220, and an ejection head 230. The carriage 210 of the printing unit 200 is connected to the first control unit 100 and the second control unit 110 via the flexible cable 130 and is configured to be movable in a state where the liquid storage unit 220 and the discharge head 230 are mounted. Yes.

  The liquid storage unit 220 of the printing unit 200 stores ink therein and supplies the ink to the ejection head 230. In the present embodiment, a plurality of liquid storage portions 220 prepared for each ink color (black, cyan, magenta, and yellow) are mounted on the carriage 210. That is, the plurality of liquid storage units 220 store different color inks associated with each.

  The ejection head 230 of the printing unit 200 is a part that can face the medium M, and the ink supplied from the liquid storage unit 220 to the ejection head 230 is ejected from the ejection head 230 toward the medium M in the form of droplets. .

  Further, the printing apparatus 10 includes a medium support unit 140 that supports the medium M, and a main scanning feed mechanism 150 and a sub-scan feed mechanism 160 that move the printing unit 200 and the medium M relatively. The main scanning feed mechanism 150 includes a carriage motor 152 and a driving belt 154, and transmits the power of the carriage motor 152 to the printing unit 200 via the driving belt 154, thereby reciprocating the printing unit 200 in the main scanning direction.

  The sub-scan feed mechanism 160 includes a transport motor 162 and a transport roller (not shown), and transports the medium M in the sub-scanning direction that intersects the main scanning direction by transmitting the power of the transport motor 162 to the transport roller. The carriage motor 152 of the main scan feed mechanism 150 and the transport motor 162 of the sub scan feed mechanism 160 operate based on control by the first control unit 100.

  In the description of the present embodiment, the X axis is set as the coordinate axis along the main scanning direction in which the printing unit 200 is reciprocated, the Y axis is set as the coordinate axis along the sub scanning direction for transporting the medium M, and the vertical The Z axis was set as the downward coordinate axis. The X axis, Y axis, and Z axis are coordinate axes that intersect (orthogonal) each other.

  As illustrated in FIG. 2, the ejection head 230 of the printing unit 200 includes a plurality of nozzles 20 that eject ink. In the present embodiment, n (for example, 360) nozzles 20 are provided for each ink color (black, cyan, magenta, and yellow), and the nozzles 20 for each color are in the main scanning direction (X-axis direction). Are arranged in the order of black, cyan, magenta, and yellow. The n nozzles 20 for each color are arranged so as to be shifted from each other in the sub-scanning direction (Y-axis direction). In this embodiment, the interval between the nozzles 20 in the sub-scanning direction (Y-axis direction) is reduced. They are arranged alternately in two rows along the direction (Y-axis direction).

  In the description of the present embodiment, the symbol “20” is used to generically refer to the nozzles in the printing unit 200, the symbol “20k” is used to specify the black nozzle, and the symbol “20” is used to specify the cyan nozzle. 20c ", the code" 20m "is used to specify the magenta nozzle, and the code" 20y "is used to specify the yellow nozzle.

  Furthermore, when specifying each nozzle, the code | symbol which added the nozzle number is used. For example, as shown in FIG. 2, the symbol “20y (1)” is assigned to the first yellow nozzle, the symbol “20y (2)” is assigned to the second nozzle of yellow, and the symbol “20y (2)” is assigned to the third nozzle of yellow. “20y (3)”,..., “20y (n−1)” is used for the (n−1) th nozzle of yellow, and “20y (n)” is used for the nth nozzle of yellow. .

  As shown in FIG. 3, the ejection head 230 of the printing unit 200 includes the nozzle 20, the introduction path 32, the reservoir 34, the supply port 36, the cavity 38, the drive element 40, the diaphragm 42, Is provided.

  The introduction path 32 and the reservoir 34 of the ejection head 230 are provided for each ink color, and form a part of a flow path for flowing ink from the liquid storage unit 220 to the nozzle 20. The ink supplied from the liquid storage unit 220 to the printing unit 200 is stored in the reservoir 34 through the introduction path 32. Further, the supply port 36, the cavity 38, the driving element 40, and the diaphragm 42 in the ejection head 230 are provided corresponding to each of the plurality of nozzles 20 formed in the ejection head 230.

  The supply port 36 and the cavity 38 of the ejection head 230 form a part of a flow path for flowing ink from the liquid container 220 to the nozzle 20. The supply port 36 is a flow path that communicates between the reservoir 34 and the cavity 38, and ink is supplied from the reservoir 34 to the cavity 38 through the supply port 36. The cavity 38 is a flow path communicating with the nozzle 20, has a flow path cross section sufficiently larger than the supply port 36 and the nozzle 20, and stores ink before ejection.

  The drive element 40 of the discharge head 230 is provided corresponding to the cavity 38 via the vibration plate 42, and the vibration plate 42 of the discharge head 230 forms a part of the flow path wall surface in the cavity 38. In this embodiment, the drive element 40 is a unimorph type piezoelectric actuator in which a piezoelectric body 46 is laminated between two electrodes 44 and 48 and a diaphragm 42 is provided on the electrode 48 side. A type piezoelectric actuator may be applied.

  The drive element 40 bends in the gravitational direction (Z-axis direction) based on the application of the drive signal, and displaces the diaphragm 42. Thus, after the volume of the cavity 38 is expanded and ink is drawn from the reservoir 34, the volume of the cavity 38 is reduced and ink droplets can be ejected from the nozzle 20.

  In the following description, as shown in FIG. 3, the configuration relating to ejection of one ink droplet is also referred to as “ejection unit 240”. That is, a plurality of ejection units 240 are provided in the ejection head 230, and are configured to include the supply port 36, the cavity 38, the nozzle 20, the driving element 40, and the diaphragm 42. For this reason, the ejection unit 240 is provided in a number corresponding to the number of nozzles n for each ink color.

  In addition, a configuration relating to ejection of one of a plurality of inks (for example, yellow ink) is also referred to as “droplet ejection unit 250”. That is, the droplet discharge unit 250 discharges one ink, a liquid storage unit 220 that stores one ink, an introduction path 32 that introduces one ink into the reservoir 34, a reservoir 34 that stores one ink. And a plurality of ejection units 240. For this reason, a plurality (four in this embodiment) of droplet ejection units 250 are provided for each ink color.

  As illustrated in FIG. 1, the printing apparatus 10 includes a maintenance unit 300 that maintains the ejection head 230 (ejection unit 240) of the printing unit 200. The maintenance unit 300 includes a wiper 310 and a cap 320. The wiper 310 of the printing apparatus 10 removes the ink attached to the ejection head 230 by wiping the ejection head 230.

  The cap 320 forms a closed space including the opening of the nozzle 20 by contacting the ejection head 230 during the standby period of the printing unit 200. Thus, the cap 320 suppresses ink drying in the ejection head 230. When the nozzle 20 of the ejection head 230 is clogged, the cap 320 is used for flushing or cleaning as an example of maintenance.

  That is, the cap 320 receives the ink droplets ejected from the nozzles 20 of the ejection head 230 when facing the ejection head 230 when performing flushing, and forms the closed space when performing cleaning. The deteriorated ink is sucked from the nozzles 20 while being in contact with the ejection head 230. The maintenance using the cap 320 can restore the nozzle 20 clogged with air bubbles or ink deteriorated due to thickening to a state where ink can be appropriately ejected.

  As shown in FIG. 1, the printing apparatus 10 includes a housing 400 that houses various configurations of the printing apparatus 10 such as the printing unit 200. A discharge port 412 that communicates the inside and outside of the housing 400 is formed on the front surface of the housing 400. The discharge port 412 is an opening through which the printed medium M is discharged inside the case 400 to the outside of the case 400.

  In addition, the housing 400 is provided with a window portion 414 that exposes the printing unit 200 and the medium support unit 140 to the outside of the housing 400 from the front surface to the upper surface. Therefore, the user can visually recognize the medium M on which the ink has been ejected while the printing apparatus 10 is printing on the medium M. Note that the window 414 may be formed of, for example, a resin or glass that transmits visible light, or may simply be an opening that communicates the inside and outside of the housing 400.

  Furthermore, the housing 400 is provided with a medium support unit 140 and an illumination unit 416 that illuminates the medium M supported by the medium support unit 140. The lighting unit 416 may be provided outside the housing 400 or inside the housing 400. Further, the illumination unit 416 may directly illuminate the medium support unit 140 or may indirectly illuminate it by reflecting the internal configuration of the housing 400.

Next, the electrical configuration of the printing apparatus 10 will be described with reference to FIG.
As shown in FIG. 4, the first control unit 100 includes a drive control unit 102, an inspection unit 104, and a storage unit 106. The printing unit 200 includes a shift register 52, a latch circuit 54, a level shifter 56, a switch 58, common electric circuits 62 and 64, a plurality of switches 66, and a detection unit 260.

  The drive control unit 102 of the first control unit 100 controls each drive of the plurality of drive elements 40 in the printing unit 200 via the common electric path 62 of the printing unit 200. In the present embodiment, the drive control unit 102 applies the drive signal COM for driving the drive element 40 to the common electric circuit 62, and shift input signal SI, clock signal SCK, latch signal LAT in accordance with the application of the drive signal COM. Is output to the printing unit 200.

  The shift register 52 of the printing unit 200 is a storage device that stores instruction data that instructs the operation of each driving element 40. In the shift input signal SI from the first control unit 100, instruction data corresponding to each driving element 40 is sequentially output in synchronization with the clock signal SCK, and the shift register 52 receives the shift input signal SI and the clock signal SCK. Based on the above, the instruction data corresponding to each drive element 40 is sequentially stored. In this embodiment, the instruction data corresponding to each driving element 40 is 2-bit data, and any one of [0, 0], [0, 1], [1, 0], and [1, 1] is selected. Show.

  Based on the latch signal LAT from the first control unit 100, the latch circuit 54 of the printing unit 200 holds the instruction data of each driving element 40 stored in the shift register 52, and performs logic according to each instruction data. The signal is output to the level shifter 56. The latch signal LAT is output from the first control unit 100 at a timing when all the instruction data of each driving element 40 is stored in the shift register 52.

  In the present embodiment, the latch circuit 54 outputs a Lo level logic signal according to the [0, 0] instruction data, and follows the Lo level according to the [0, 1] instruction data. In response to the [1,0] instruction data, the Lo level logic signal is output following the [1,0] instruction data, and the Hi level logic signal is output according to the [1,1] instruction data.

  The level shifter 56 of the printing unit 200 is connected to each of the plurality of switches 66 connected to each driving element 40 in accordance with the logic signal output from the latch circuit 54, and the voltage at a level at which each switch 66 can be turned on / off. Is output. In the present embodiment, the level shifter 56 outputs a voltage at a level that turns off the switch 66 according to the Lo level logic signal from the latch circuit 54, and switches according to the Hi level logic signal from the latch circuit 54. The voltage of the level which turns 66 on is output.

  The plurality of switches 66 in the printing unit 200 turn on / off the electrical connection between the common electric circuit 62 and each driving element 40. A driving signal COM for driving the driving element 40 is input from the first control unit 100 to the common electric path 62 of the printing unit 200. In the ON state in which the driving element 40 is electrically connected to the common electric circuit 62 by the switch 66, the driving signal COM is applied to the electrode 44 side of the driving element 40, and the driving element 40 is electrically connected from the common electric circuit 62 by the switch 66. In the disconnected off state, the drive signal COM is not applied to the drive element 40. In the present embodiment, the switch 66 is an analog switch using a transmission gate.

  The switch 58 of the printing unit 200 electrically connects (grounds) the common electric circuit 64 electrically connected to the electrode 48 side of each drive element 40 to the ground line GL. The ground line GL is an electrical conductor connected to a reference potential point in the printing apparatus 10 and is connected to the casing 400 of the printing apparatus 10 in the present embodiment.

  A resistor 59 is connected electrically in parallel with the switch 58 between the common electric circuit 64 and the ground line GL. Based on the detection execution signal DSEL output from the first control unit 100, the detection unit 260 detects the current flowing through the resistor 59 while the switch 58 electrically disconnects the common circuit 64 from the ground line GL. The electric signal HGND output from the common circuit 64 is detected by amplifying the voltage change based on the operational amplifier. Accordingly, the detection unit 260 effectively detects the electromotive force applied from each drive element 40 to the common electric circuit 64 based on the voltage change between the electric signal HGND of the common electric circuit 64 and the ground line GL. Can do.

  The detection unit 260 of the printing unit 200 detects vibration (vibration of the vibration plate 42 in the present embodiment) generated by driving the drive element 40. In the present embodiment, the detection unit 260 detects residual vibration that is vibration that remains after the drive element 40 is driven due to the drive of the drive element 40. The drive element 40 functions as a sensing unit that senses residual vibration and outputs an electric signal SW corresponding to the residual vibration, and is output from each drive element 40 to the common electric path 64 by an electromotive force associated with the residual vibration. An electric signal (hereinafter also referred to as “electric signal SW”) is applied.

  That is, the detection unit 260 detects the electric signal SW as residual vibration by measuring the electric signal HGND of the common electric circuit 64. Thus, the detection unit 260 detects the electrical signal SW in accordance with the detection execution signal DSEL output from the first control unit 100, and outputs the electrical signal SW to the second control unit 110 as the detection signal POUT1.

  Next, an example of various signals in the first control unit 100, the second control unit 110, and the printing unit 200 will be described with reference to FIGS. 5A to 5D illustrate changes in the latch signal LAT, switching signal CH, drive signal COM, and detection execution signal DSEL over time, and FIGS. 5E to 5H are shifts. The time change of the applied voltage applied to the drive element 40 according to the instruction data of the input signal SI is illustrated.

  As shown in FIG. 5A, the latch signal LAT is a logic signal that rises in accordance with the driving cycle TD, and is input from the first control unit 100 to the latch circuit 54. The driving period TD corresponds to a period in which one pixel is generated on the medium M by driving the driving element 40 of the ejection unit 240.

  As shown in FIG. 5B, the switching signal CH is a signal generated in the printing unit 200 based on the latch signal LAT, and is a logic signal that rises as the specified time elapses from the rise of the latch signal LAT. . The latch circuit 54 outputs a logic signal corresponding to the first bit in the 2-bit instruction data received from the shift register 52 during the first period T1 from the rising edge of the latch signal LAT to the rising edge of the switching signal CH. The latch circuit 54 outputs a logic signal corresponding to the second bit of the instruction data during the second period T2 from the rising edge of the switching signal CH to the next rising edge of the latch signal LAT.

  As shown in FIG. 5C, the drive signal COM is a voltage signal periodically output in synchronization with the drive cycle TD, and the drive element 40 is passed from the first controller 100 through the common electric circuit 62 and the switch 66. To be supplied. In the first period T1, the drive signal COM rises from a state in which the intermediate voltage Vc is maintained to a voltage V1 higher than the intermediate voltage Vc, then falls to a voltage V2 lower than the intermediate voltage Vc, and again returns to the intermediate voltage V1. Vc. In the subsequent second period T2, the drive signal COM rises from the intermediate voltage Vc to the voltage V1 higher than the intermediate voltage Vc, and then maintains the intermediate voltage Vc.

  Here, the drive signal COM in the first period T1 is a signal at an application level for ejecting ink droplets from the nozzle 20. Further, the drive signal COM in the second period T2 is a signal at an application level that generates vibration without causing ink droplets to be ejected from the nozzles 20.

  As shown in FIG. 5D, the detection execution signal DSEL is detected from the timing when the drive signal COM returns from the voltage V1 to the intermediate voltage Vc in the second period T2 when the ejection unit 240 is inspected based on the residual vibration. The logic signal falls until the timing before the end of the second period T2. When the detection execution signal DSEL falls, the switch 58 of the printing unit 200 electrically disconnects the common circuit 64 from the ground, and the detection unit 260 of the printing unit 200 detects the electric signal HGND of the common circuit 64.

  As shown in FIG. 5E, when the instruction data of the shift input signal SI is [0, 0], the applied voltage applied to the drive element 40 is in a state where the intermediate voltage Vc is maintained during the drive cycle TD. It becomes. As a result, ink droplets are not ejected in the ejection section 240 corresponding to the drive element 40, and no vibration is generated. The instruction data [0, 0] of the shift input signal SI is set for the ejection unit 240 that does not form pixels at the time of printing or the ejection unit 240 that is not a target for inspection based on residual vibration.

  As shown in FIG. 5F, when the instruction data of the shift input signal SI is [0, 1], the applied voltage applied to the driving element 40 is maintained at the intermediate voltage Vc in the first period T1, In the second period T2, the voltage rises to V1. As a result, vibration can be generated in the discharge section 240 corresponding to the drive element 40 without discharging ink droplets. The instruction data [0, 1] of the shift input signal SI is set for the ejection unit 240 to be subjected to the inspection based on the residual vibration when the inspection is performed without forming pixels.

  As shown in FIG. 5G, when the instruction data of the shift input signal SI is [1, 0], the applied voltage applied to the driving element 40 has changed to the voltage V1 and the voltage V2 in the first period T1. Thereafter, the intermediate voltage Vc is maintained in the second period T2. As a result, ink droplets are ejected from the ejection section 240 corresponding to the drive element 40. The instruction data [1, 0] of the shift input signal SI is set for the ejection unit 240 that forms pixels during printing.

  As shown in FIG. 5 (h), when the instruction data of the shift input signal SI is [1, 1], the applied voltage applied to the driving element 40 is changed to the voltage V1 and the voltage V2 in the first period T1. Thereafter, the voltage changes to the voltage V1 in the second period T2. As a result, the ejection unit 240 corresponding to the drive element 40 can generate vibrations suitable for the inspection of the ejection unit 240 while ejecting ink droplets. The instruction data [1, 1] of the shift input signal SI is set for the ejection unit 240 to be subjected to inspection based on residual vibration when performing inspection while forming pixels.

  Returning to the description of FIG. 4, the second control unit 110 receives the detection signal POUT <b> 1 from the detection unit 260 of the printing unit 200. Further, the second control unit 110 outputs the control signal POUT2 toward the first control unit 100. Here, the control signal POUT2 may be a signal that is equal to the detection signal POUT1 from the detection unit 260, or may be a substitute signal generated by the second control unit 110.

  As shown in FIG. 4, the inspection unit 104 of the first control unit 100 receives the control signal POUT2 from the second control unit 110, and based on the period of the residual vibration indicated by the control signal POUT2, the discharge unit 240. Inspect. In addition, the inspection unit 104 identifies the state of the discharge unit 240 from a normal state, a non-discharge state due to bubble mixing, and a non-discharge state due to thickening. The normal state is a state in which ink can be ejected at a prescribed droplet deposition position and droplet deposition shape. The non-ejection state due to mixing of bubbles is a state where ink cannot be discharged due to mixing of bubbles in the ink in the cavity 38. The non-ejection state due to thickening is a state where ink cannot be ejected due to thickening of the ink in the cavity 38.

  The storage unit 106 of the first control unit 100 stores determination criterion data 107 and inspection result data 108. The determination criterion data 107 in the storage unit 106 is data indicating a determination criterion for determining the state of the ejection unit 240 based on the electrical signal SW. In the present embodiment, each type of ink is stored in the storage unit 106 when the printing apparatus 10 is shipped from the factory. The inspection result data 108 in the storage unit 106 is data indicating the inspection result of the ejection unit 240 by the inspection unit 104 and is stored in the storage unit 106 in accordance with the inspection performed by the inspection unit 104.

  In addition, when the user performs printing using the printing apparatus 10, a flag (hereinafter referred to as “flag”) in which a value for selecting whether to give priority to print quality or print speed is set in the storage unit 106. Also referred to as “Flg”). When priority is given to the print quality, “0 (zero)” is set to the flag Flg, and when priority is given to the print speed, “1” is set to the flag Flg.

  Next, an example of a change in the electrical signal SW according to the residual vibration will be described with reference to FIG. In FIG. 6, the vertical axis represents voltage, the horizontal axis represents time, and the temporal changes of the electrical signals SWg, SWb, SWv with respect to the reference voltage Vref are illustrated.

  The electric signal SWg in FIG. 6 indicates the electric signal SW corresponding to the residual vibration in the ejection unit 240 in a normal state where ink can be ejected. The electric signal SWb in FIG. 6 indicates the electric signal SW corresponding to the residual vibration in the discharge unit 240 in the non-discharge state due to the mixing of bubbles. The electric signal SWv in FIG. 6 indicates the electric signal SW corresponding to the residual vibration in the discharge unit 240 in the non-discharge state due to thickening.

  Here, when the step response when the pressure P is applied to the simple vibration calculation model assuming the diaphragm 42 in the discharge unit 240 is calculated for the volume velocity u, the following mathematical formulas 1a, 1b, and 1c are obtained.

In the above formulas 1a, 1b, and 1c, the flow path resistance r depends on the flow path shapes of the supply port 36, the cavity 38, the nozzle 20, and the like, and the viscosity of the ink in these flow paths, and the inertance m is the supply port 36. The compliance c depends on the stretchability of the vibration plate 42, depending on the mass of ink in the flow path such as the cavity 38 and the nozzle 20.

  In the non-ejection state due to bubble mixing, the ink in the cavity 38 is reduced, and the inertance m mainly decreases. As the inertance m decreases, the angular velocity ω increases, as is apparent from Equation 1b. Therefore, as shown in FIG. 6, the cycle tC_b of the electrical signal SWb in the non-ejection state due to the mixing of bubbles is shorter than the cycle tC_g of the electrical signal SWg in the normal state.

  In the non-ejection state due to thickening, the ink in the cavity 38 thickens, so the flow path resistance r increases. As the flow path resistance r increases, the angular velocity ω decreases, as is apparent from Equations 1b and 1c. Therefore, as shown in FIG. 6, the cycle tC_v of the electrical signal SWv in the non-ejection state due to thickening is longer than the cycle tC_g of the electrical signal SWg in the normal state, and the attenuation amount of the electrical signal SWv is the electrical signal SWg. Bigger than.

  Therefore, in the present embodiment, when the cycle of the electrical signal SW (hereinafter also referred to as “cycle tC”) is not less than the lower limit cycle tC_L and less than the upper limit cycle tC_H (tC_L ≦ tC <tC_H), the state of the discharge unit 240 Is determined to be in a normal state. In addition, when the cycle tC of the electrical signal SW is less than the lower limit cycle tC_L (tC <tC_L), it is determined that a discharge failure due to bubble mixing has occurred in the discharge unit 240. Further, when the cycle tC of the electric signal SW is equal to or longer than the upper limit cycle tC_H (tC_H ≦ tC), it is determined that a discharge failure due to thickening occurs in the discharge unit 240. Here, it is desirable that the magnitudes of the lower limit period tC_L and the upper limit period tC_H are arbitrarily set by experiments or the like.

  In the following description, an electric signal SW whose cycle tC is less than the lower limit cycle tC_L, such as the electric signal SWb, or an electric signal SW whose cycle tC is the upper limit cycle tC_H or more, such as the electric signal SWv, is also referred to as “first signal”. say. An electric signal SWg having a period tC that is equal to or greater than the lower limit period tC_L and less than the upper limit period tC_H is also referred to as a “second signal”.

  FIG. 6 illustrates the periods tC_g, tC_b, and tC_v as the first periods of the electric signals SWg, SWb, and SWv. However, theoretically, the periods of the electric signals SWg, SWb, and SWv are constant, The periods after the period (second period, third period,...) Are the same as the values of the periods tC_g, tC_b, and tC_v, respectively.

Next, a processing routine executed when the first control unit 100 and the second control unit 110 perform printing on the medium M will be described with reference to flowcharts shown in FIGS.
First, the processing routine executed by the first control unit 100 will be described with reference to the flowchart shown in FIG. This processing routine is a processing routine that is executed each time a printing instruction is issued to the printing apparatus 10.

  As shown in FIG. 7, in this processing routine, the first control unit 100 executes a printing process (step S11), and executes an inspection process shown in FIG. 8 (step S12). Here, the printing process is one-pass printing in which ink is ejected from the ejection head 230 toward the medium M while the printing unit 200 is moved from one end side to the other end side in the main scanning direction by the main scanning feed mechanism 150. And a process for printing for a plurality of passes. Examples of printing for a plurality of passes include printing of one image and printing on one medium M.

  Further, the inspection process is to determine whether or not a discharge failure has occurred by detecting residual vibration due to driving of the drive element 40 in the discharge unit 240 that discharges ink used for printing when printing on the medium M. This is a process for inspection.

  Then, the first control unit 100 determines whether or not the discharge unit 240 needs to be maintained based on the result of the inspection process shown in FIG. 8 (step S13). Here, whether or not maintenance is necessary may be determined for each discharge unit 240 or for each droplet discharge unit 250.

  Subsequently, when maintenance is not necessary (step S13: NO), the first control unit 100 shifts the process to the next step S15. On the other hand, if maintenance is required (step S13: YES), maintenance is performed for at least the discharge unit 240 determined to have a discharge failure (step S14), and the process proceeds to the next step S15. To do. Here, the discharge unit 240 in which maintenance is performed may be only the discharge unit 240 determined to have a discharge failure, or all of the discharge units of the droplet discharge unit 250 having the discharge unit 240. 240 may be sufficient.

  In step S15, the first control unit 100 determines whether or not all printing has been completed. If all printing has not been completed (step S15: NO), the process proceeds to the previous step S11. Then, processing for performing the remaining printing is performed. On the other hand, when all printing is completed (step S15: YES), the first control unit 100 determines whether or not “1” is set in the flag Flg (step S16).

  In the present embodiment, the case where all the printing is completed corresponds to “the ejection of the ink to the medium M of the ejection unit 240 is completed”, and the case where all the printing is not completed is “the ejection unit 240 has completed. This corresponds to “in the middle of ejecting ink toward the medium M”.

  When “1” is not set in the flag Flg (step S16: NO), that is, when priority is given to print quality, maintenance is appropriately performed at the timing when ejection failure occurs, and therefore maintenance is repeated. Without executing, the first control unit 100 once ends this processing routine. In this case (step S16: NO) is a case where the second control unit 110 does not output an alternative signal (second signal) to the first control unit 100 (step S44).

  On the other hand, when “1” is set in the flag Flg (step S16: YES), that is, when priority is given to the printing speed, the maintenance may not be performed when the maintenance should be performed. 1 control part 100 performs maintenance of discharge part 240 (Step S17). In this case (step S16: YES), the second control unit 110 outputs a substitute signal (second signal) to the first control unit 100 (step S45). In step S <b> 17, it is desirable that the discharge units 240 on which maintenance is performed are all the discharge units 240.

Next, an inspection processing routine (subroutine) executed by the first control unit 100 will be described with reference to the flowchart shown in FIG.
As shown in FIG. 8, the first control unit 100 selects one ejection unit 240 to be a target (inspection target) for determining whether or not ejection failure has occurred (step S21), and selects the selected one. The drive element 40 of the discharge part 240 is driven (step S22). Specifically, [0, 1] is set in the instruction data of the shift input signal SI corresponding to the ejection unit 240 to be inspected, and [0, 1] is set in the instruction data of the shift input signal SI corresponding to the other ejection units 240. , 0], the latch signal LAT, the drive signal COM, and the detection execution signal DSEL are output to the printing unit 200 together with the shift input signal SI and the clock signal SCK.

  As a result, the electric signal SW corresponding to the residual vibration is applied to the common electric path 64 from the drive element 40 in the ejection unit 240 to be inspected. At that time, the electric signal HGND of the common electric circuit 64 detected by the detecting unit 260 of the printing unit 200 becomes an electric signal SW corresponding to the residual vibration in the ejection unit 240 to be inspected. In addition, the detection unit 260 outputs the electric signal SW to the second control unit 110 as the detection signal POUT1.

  Subsequently, the first control unit 100 detects the control signal POUT2 output from the second control unit 110 to which the detection signal POUT1 is input (step S23). Here, the first control unit 100 acquires the period tC of the residual vibration in the ejection unit 240 that is the inspection target indicated by the control signal POUT2.

  Then, the first control unit 100 executes a determination process for determining whether or not a discharge failure has occurred in the discharge unit 240 to be inspected based on the control signal POUT2 (cycle tC) (step S1). S24), the determination result is stored in the storage unit 106 as the inspection result data 108 (step S25).

  Subsequently, the first control unit 100 determines whether or not all ejection units 240 have been inspected as inspection targets (step S26), and when all the ejection units 240 have not been inspected (step S26: NO). Then, the process proceeds to the previous step S21, and a process for inspecting the remaining ejection units 240 is performed. On the other hand, when all the ejection units 240 are inspected (step S26: YES), the first control unit 100 once ends this processing routine.

Next, a determination processing routine (subroutine) executed by the first control unit 100 will be described with reference to the flowchart shown in FIG.
As shown in FIG. 9, the first control unit 100 determines whether or not the residual vibration period tC indicated by the control signal POUT2 is less than the lower limit period tC_L (step S31). When the cycle tC is less than the lower limit cycle tC_L (step S31: YES), the first control unit 100 determines that a discharge failure due to bubble mixing has occurred in the discharge unit 240 to be inspected (step S32).

  On the other hand, when the cycle tC is equal to or greater than the lower limit cycle tC_L in step S31 (step S31: NO), the first controller 100 determines whether or not the cycle tC is equal to or greater than the upper limit cycle tC_H (step S33). . When the cycle tC is equal to or greater than the upper limit cycle tC_H (step S33: YES), it is determined that an ejection failure has occurred due to ink thickening in the ejection unit 240 to be inspected (step S34).

  On the other hand, when the cycle tC is less than the upper limit cycle tC_H in step S33 (step S33: NO), the first control unit 100 determines that no ejection failure has occurred in the ejection unit 240 to be inspected (step S33). S35). Then, the first control unit 100 thereafter ends this processing routine once.

Next, a processing routine (main routine) executed by the second control unit 110 will be described with reference to the flowchart shown in FIG.
As shown in FIG. 10, the second control unit 110 determines whether or not the detection execution signal DSEL has been detected (step S41). When the detection execution signal DSEL has not been detected (step S41: NO), The second control unit 110 once ends this processing routine. On the other hand, when the detection execution signal DSEL is detected (step S41: YES), the detection execution signal DSEL is output to the printing unit 200, thereby detecting the detection signal POUT1 output from the detection unit 260 (step S42).

  Subsequently, the second control unit 110 determines whether or not “1” is set in the flag Flg (step S43). When “0 (zero)” is set in the flag Flg (step S43: NO), the second control unit 110 sets the same signal as the detection signal POUT1 as the control signal POUT2 to the first control unit 100. In step S44, the processing routine is terminated. That is, in step S44, if the detection signal POUT1 is the first signal, the signal is output to the first control unit 100. If the detection signal POUT1 is the second signal, the signal is output to the first control unit 100. Is output.

  On the other hand, when “1” is set in the flag Flg (step S43: YES), the second control unit 110 sets the substitute signal (second signal) as the control signal POUT2 to the first control unit 100. Output (step S45). Thereafter, this processing routine is terminated. That is, in step S45, the second signal is output to the first control unit 100 regardless of whether the detection signal POUT1 is the first signal or the second signal.

  In this respect, in this embodiment, the second control unit 110 selects the second signal as the control signal POUT2 by selecting whether to set “0 (zero)” or “1” in the flag Flg. It is possible to select whether or not to output a signal.

  In step S44, when the electrical signal SW (first signal) having the cycle tC less than the lower limit cycle tC_L or the cycle tC being the upper limit cycle tC_H is output as the control signal POUT2, the first control that has received the signal The unit 100 determines that a discharge failure has occurred in the discharge unit 240 to be inspected due to thickening or bubble mixing (steps S32 and S34). That is, in this case, in order to recover the ejection failure in the ejection unit 240, maintenance of the ejection unit 240 to be inspected is performed (step S14).

  In Step S44, when the electrical signal SW (second signal) having the cycle tC that is equal to or greater than the lower limit cycle tC_L and less than the upper limit cycle tC_H is output as the control signal POUT2, the first control that has received the signal The unit 100 determines that no ejection failure has occurred in the ejection unit 240 to be inspected (step S35). That is, in this case, the discharge unit 240 to be inspected does not actually have a discharge failure and maintenance is not performed.

  In step S45, when the electric signal SW (second signal) having the cycle tC that is equal to or greater than the lower limit cycle tC_L and less than the upper limit cycle tC_H is output as the control signal POUT2, the first control that has received the signal The unit 100 determines that no ejection failure has occurred in the ejection unit 240 to be inspected (step S35). However, in this case, in the ejection unit 240 to be inspected, in some cases, ejection failure may actually occur, but the maintenance is not performed in order to reduce downtime due to maintenance.

Next, the operation of the printing apparatus 10 of this embodiment will be described.
When printing is performed on the medium M in the printing apparatus 10 according to the present embodiment, ink is ejected from the ejection unit 240 included in the ejection head 230 toward the medium M.

  When a discharge failure occurs in the discharge unit 240 during printing on the medium M, when the user has set the print quality to be more important than the print speed (step S43: NO), Printing is interrupted (step S13: YES). Subsequently, at least the discharge unit 240 in which the discharge failure has occurred is maintained (step S14).

  On the other hand, if a discharge failure occurs in the discharge unit 240 during printing on the medium M, the user has set the print speed to be more important than the print quality (step S43: YES). Printing is continued on the medium M without being interrupted (step S13: NO). Thus, the occurrence of downtime during which printing cannot be performed is suppressed.

  Further, when the printing on the medium M is continued without interrupting the printing, when all the printing (for example, all the printing jobs) is completed, all the discharging units 240 of the discharging head 230 are targeted. Maintenance is executed (step S16: YES, step S17). For this reason, in the discharge part 240, it is suppressed that the state in which the discharge defect has arisen is continued.

  In addition, even when the printing on the medium M is continued without being interrupted, the result of the user viewing the medium M on which the ink has been ejected through the window 414 provided in the housing 400. If it is determined that the print quality is unacceptable, the user stops the printing and causes the discharge unit 240 to perform maintenance. At this time, since the medium M on which the ink has been ejected is illuminated by the illumination unit 416 provided in the housing 400, the user can more easily see the medium M.

According to the above embodiment, the following effects can be obtained.
(1) Since the second control unit 110 capable of outputting the second signal is provided, detection is performed when the second signal is input from the second control unit 110 to the first control unit 100. Even when the unit 260 outputs the first signal, the maintenance of the discharge unit 240 can be prevented from being executed. Therefore, according to this configuration, it is possible to reduce downtime during which the ejection unit 240 cannot eject ink.

  (2) When the maintenance of the discharge unit 240 is not performed during printing, the maintenance of the discharge unit 240 is performed after all the printing is completed. According to this, maintenance of the discharge unit 240 is performed after the end of printing, so that it is possible to suppress a state in which a discharge failure has occurred in the discharge unit 240 from being continued.

  (3) Depending on the value set in the flag Flg, whether or not the user gives priority to print quality by switching whether or not the second control unit 110 outputs the substitute signal (second signal) as the control signal POUT2 is printed. You can choose whether to prioritize speed.

  (4) The user of the printing apparatus 10 can visually recognize the medium M on which ink is ejected to the ejection unit 240 via the window 414 provided in the housing 400. Therefore, the user can determine whether or not the maintenance of the ejection unit 240 is necessary by visually recognizing the medium M on which the ink has been ejected. Therefore, the second control unit 110 outputs the second signal, so that even when maintenance is not performed, the user can perform maintenance of the discharge unit 240 at an appropriate timing.

  (5) The illumination unit 416 provided in the housing 400 illuminates the medium M on which the ink is ejected onto the ejection unit 240, so that the user of the printing apparatus 10 can more easily see the medium M on which the ink has been ejected. Become. For this reason, the user can more easily determine whether maintenance is necessary.

You may change the said embodiment as shown below.
-The value set in the flag Flg may be changed according to a preset time zone. That is, if it is a time zone in which the user exists around the printing apparatus 10, the flag Flg is set to “1”, whereas if it is not a time zone in which the user exists around the printing apparatus 10, the flag Flg “0 (zero)” may be set to. According to this, when there is no user around the printing apparatus 10 and the user cannot visually recognize the medium M on which the ink has been ejected, the second control unit 110 outputs the second signal. The discharge unit 240 can be maintained at the timing when discharge failure occurs.

  In the above embodiment, when “1” is set in the flag Flg, maintenance is performed for all the ejection units 240 after printing is completed, but ejection failure occurs after printing is completed. Maintenance may be performed only on the discharge unit 240 in which the occurrence of the problem occurs.

In the above embodiment, the drive element 40 is used to detect the residual vibration in the discharge unit 240. However, a dedicated sensor that senses the residual vibration may be provided separately from the drive element 40.
In the above embodiment, the residual vibration is detected by driving the driving element 40 at an application level that generates residual vibration without discharging ink droplets. However, the driving element 40 is driven at an application level that discharges ink drops. Residual vibration may be detected.

  In the above-described embodiment, the presence or absence of ejection failure of the ejection unit 240 is inspected based on the residual vibration period tC. However, a determination threshold value used for determination based on the phase and amplitude of the residual vibration is set in the determination reference data 107. Alternatively, the inspection may be performed based on at least one of the phase and the amplitude in addition to the period tC of the residual vibration. Alternatively, the inspection processing may be performed by setting the vibration waveform itself of the residual vibration in the determination reference data 107 and comparing the vibration waveforms.

  In the above embodiment, the signal level of the drive signal for driving the drive element 40 in each ejection unit 240 is one of the voltages V1, but in other embodiments, the signal level of the drive signal (for example, for each rank) (for example, , Voltage, current, electric energy, etc.) may be set in the determination reference data 107, and the inspection process may be performed according to the signal level of the drive signal. Accordingly, it is possible to further suppress the erroneous determination of the inspection based on the residual vibration in consideration of the characteristic of the residual vibration that changes according to the signal level of the drive signal.

  The vibration detected by the detection unit 260 may be vibration caused by driving of the driving element 40. For example, vibration of ink in the cavity 38 due to driving of the driving element 40 may be detected. The vibration of the drive element 40 after the drive of 40 may be detected.

  A means for sensing vibration caused by driving of the drive element 40 may be provided for each nozzle 20, or may be provided for two or more nozzles 20. In addition, a means for sensing vibration caused by driving of the drive element 40 may be provided in the cavity 38 or in the supply port 36 or the reservoir 34.

  The timing for detecting vibration due to driving of the driving element 40 is not limited to after driving of the driving element 40, but may be before driving of the driving element 40, at the same time as driving, or during driving Good.

-The window part 414 and the illumination part 416 provided in the housing | casing 400 do not need to be provided.
In the flowchart shown in FIG. 7, steps S16 and S17 may be omitted. That is, even when the second control unit 110 outputs the second signal to the first control unit 100, the maintenance of the ejection unit 240 does not have to be performed after the completion of all printing.

  The printing apparatus 10 may not be a serial printer that ejects ink while reciprocating in the width direction X of the medium M as in the above embodiment. For example, a line printer that ejects ink in a state where the ejection unit 240 has a length corresponding to the entire width of the medium M and is fixedly arranged may be used.

The printing apparatus 10 may be a liquid droplet ejection apparatus that ejects liquid droplets onto the medium M supported by the medium support unit 140 for purposes other than printing.
The droplets ejected by the ejection unit 240 are not limited to ink, and may be, for example, a liquid material in which particles of a functional material are dispersed or mixed in a liquid. For example, it discharges a liquid that contains materials such as electrode materials and color materials (pixel materials) used in the manufacture of liquid crystal displays, EL (electroluminescence) displays, and surface-emitting displays. Also good.

  The medium M may be a paper, a cloth such as a T-shirt, a plastic film, a thin plate, or the like, or another material.

  DESCRIPTION OF SYMBOLS 10 ... Printing apparatus (an example of a droplet discharge apparatus), 40 ... Drive element, 100 ... 1st control part, 110 ... 2nd control part, 240 ... Discharge part, 260 ... Detection part, 300 ... Maintenance part, 400 ... housing, 414 ... window, 416 ... illumination, M ... medium, POUT1 ... detection signal, POUT2 ... control signal.

Claims (5)

An ejection unit having a drive element that is driven to eject droplets toward the medium;
A detection unit that outputs a detection signal corresponding to vibration generated in the discharge unit by driving the drive element;
A maintenance unit for performing maintenance to discharge liquid from the discharge unit;
When it can be determined that a discharge failure has occurred in the discharge unit based on the detection signal, the maintenance of the discharge unit is performed, while when it can be determined that no discharge failure has occurred in the discharge unit A first control unit that does not perform the maintenance of the discharge unit,
The first control unit uses the detection signal when it is determined that a discharge failure has occurred in the discharge unit as the first signal, while the detection signal when it is determined that no discharge failure has occurred. A second control unit capable of outputting the second signal when the second signal is used;
The liquid droplet ejection apparatus, wherein the first control unit does not perform the maintenance of the ejection unit when the second signal is input from the second control unit. When the second signal is input from the second control unit while the ejection unit is ejecting droplets toward the medium, the first control unit The droplet discharge apparatus according to claim 1, wherein the maintenance of the discharge unit is executed after the discharge of the droplet to the liquid is completed. The droplet discharge apparatus according to claim 1, wherein the second control unit can select whether or not to output the second signal. A housing that accommodates at least the discharge unit;
4. The window according to claim 1, wherein the casing is provided with a window that exposes the medium from which droplets are ejected to the ejection unit to the outside of the casing. The droplet discharge device according to 1. The droplet discharge device according to claim 4, further comprising an illumination unit that illuminates the medium on which the droplet is discharged to the discharge unit.