JP2019018379A - Inkjet recording device and ink discharge quality recovery method of the same - Google Patents

Abstract

To maintain output image quality by realizing proper recovery processing.SOLUTION: A printer includes: a recording head 131 which discharges an ink from multiple discharge ports 132 facing a label sheet P to form images; a cap 133 which is detachably attached to a formation surface 131a of the discharge ports of the recording head; and an ink processing system 141 which causes the cap to be attached to the recording head to recover ink discharge quality of the discharge ports. The printer includes a CPU which obtains an ink adhesion state in which ink mist occurring during discharge of the ink from the discharge ports adheres to the formation surface of the discharge ports to control the ink processing system.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ink jet recording apparatus that avoids ejection failure due to ink thickening and an ink ejection quality recovery method thereof.

  Inkjet recording apparatuses are widely used in printers that form images on recording media such as roll paper and cut paper. This ink jet recording apparatus employs a recording method in which an image is formed on a recording medium by ejecting ink as granular ink droplets from the ejection port of the recording head. For this reason, in the ink jet recording apparatus, as the ink waiting in the ejection port of the recording head progresses in drying, the viscosity increases, so-called thickening, and the ink quality deteriorates. As a result, the ejection quality of the ink droplets is lowered, and clogging is likely to occur at the ejection port.

  For this reason, the ink jet recording apparatus includes a mechanism for attaching and detaching a cap that covers the formation surface of the ejection port of the recording head. Further, this ink jet recording apparatus is provided with a mechanism for performing a recovery process such as sucking a certain amount of ink from the inside of the ejection port in order to eliminate the thickened state or clogging of the ink in the ejection port of the recording head. .

  For example, in the ink jet recording apparatus described in Patent Document 1, the increase in ink in the ejection port is determined based on the elapsed time from the end of the most recent recovery process or the accumulated time in the exposed state exposed to the outside air without a cap. The recovery process is executed by determining the ink suction strength by determining the viscosity.

JP 2012-96367 A

  By the way, in the ink jet recording apparatus, since the ink ejected from the ejection port of the recording head flies toward the recording medium, droplet-like ink is generated and adheres to the surface of the peripheral member as so-called ink mist. The ink mist is dried while adhering to the ejection port formation surface of the recording head. In this state, when the cap is attached to the ejection port formation surface of the recording head, the dried ink mist and the standby ink in the ejection port exist in a common space in the cap, and the evaporation component is between them. Are equilibrated.

  Therefore, the processing conditions for recovering the viscosity by sucking the ink in the discharge port of the recording head, for example, the suction strength in the recovery processing is the elapsed time from the end of the most recent recovery processing or the accumulated time in the exposure state It may not be sufficient to just decide. In this case, since the ink is unexpectedly thickened and the discharge quality is deteriorated, the image quality (output image quality) to be formed may be deteriorated.

  For this reason, if the process of sucking the ink in the discharge port of the recording head and recovering the viscosity is executed in a dark manner, the ink sucked in the recovery process is consumed (discarded), leading to an increase in cost. .

  Therefore, an object of the present invention is to provide an ink jet recording apparatus capable of maintaining output image quality by realizing an appropriate recovery process and an ink discharge quality recovery method thereof.

  One aspect of the invention of an ink jet recording apparatus that solves the above problems is a recording head that discharges ink from an ejection port to form an image on a recording medium, and a recovery unit that performs a recovery operation to recover the ejection performance of the ejection port; And a control unit that controls a recovery operation performed by the recovery unit based on an adhesion state of the ink adhered to the formation surface of the ejection port.

  An aspect of the invention of an ink discharge quality recovery method for an ink jet recording apparatus that solves the above problems includes a recording head that forms an image on a recording medium by discharging ink from the discharge port, and a recovery unit that recovers the discharge performance of the discharge port An ink discharge quality recovery method executed in an ink jet recording apparatus comprising: an ink attachment state attached to a forming surface of the discharge port; and a recovery performed by the recovery unit based on the attachment state It is characterized by controlling the operation.

  According to these aspects of the present invention, the adhesion state of the ink adhering to the ejection port formation surface of the recording head is acquired, and the processing operation for recovering the ejection performance of the ejection port is executed based on the adhesion state.

  Therefore, it is possible to maintain an ink quality while avoiding a recovery process due to waste of wasted ink, and to provide an ink jet recording apparatus that realizes high-quality image formation at an appropriate cost and an ink discharge quality recovery method thereof Can do.

FIG. 1 is a schematic overall configuration diagram showing an ink jet recording apparatus that executes an ink ejection quality recovery method according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating the configuration of the control unit. FIG. 3 is a system diagram illustrating the ink ejection. FIG. 4 is a flowchart for explaining the necessity determination of the recovery process. FIG. 5 is a list for determining the mist generation coefficient used in the necessity determination. FIG. 6 is a list for determining the mist fixing level used in the necessity determination. FIG. 7 is a flowchart for explaining the execution of the recovery process. FIG. 8 is a list for determining the suction pressure of the ink used in the recovery process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 8 are diagrams illustrating a printer which is an example of an ink jet recording apparatus according to an embodiment of the present invention and an ink discharge quality recovery method thereof. FIG. 1 is an overall configuration of an image recording system including the printer. It is a conceptual relationship figure explaining these.

  In FIG. 1, a printer 100 is a recording apparatus that forms and prints an image by an inkjet recording method using a label sheet P temporarily attached with a plurality of labels and wound in a roll shape as a recording medium. For example, a terminal device E of a PC (Personal Computer) is connected to the printer 100. Based on the image data sent from the PC terminal device E, the printer 100 ejects each color ink from the ejection port 132 (see FIG. 3) of the recording head 131 for each label of the label paper P at the image forming position. To form an image.

  Here, in the present embodiment, a roll-shaped label paper (roll paper) P will be described as an example of the recording medium. However, the present invention is not limited to this, and for example, a cut paper that has been cut into a predetermined size. Other forms may be used. Needless to say, the present invention may be applied to a printer that forms an image on a recording medium other than paper.

  The printer 100 records and forms image data received from the PC terminal device E on the conveyed label paper P by the control unit 150 controlling each part of the apparatus such as the paper unit 110 and the recording unit 130.

  The paper unit 110 includes a paper feed unit 111 and a transport unit 121, and feeds and feeds the label paper P to the recording unit 130 and carries it out of the apparatus after image formation.

  The paper feed unit 111 includes a paper shaft 112, a roll motor 114, and a paper feed belt 115. Unused roll-shaped label paper P is set on the paper shaft 112. A paper feed belt 115 is wound around the paper shaft 112 together with the drive shaft 114 a of the roll motor 114.

  Thus, the paper feeding unit 111 rotates the roll motor 114 forward so as to apply a desired load, and feeds the label paper P to the transport unit 121 while applying tension so as not to loosen. Further, the paper feed unit 111 can rewind the label paper P around the paper shaft 112 by the reverse rotation of the roll motor 114.

  The transport unit 121 includes a driven roller pair 122, a transport roller pair 123, a transport motor 124, a drive belt 125, a paper sensor 127, an encoder 128, and a platen 129. In the transport unit 121, the driven roller pair 122 is disposed on the upstream side in the transport direction of the label paper P with respect to the platen 129 at the image forming position, and the transport roller pair 123 is disposed on the downstream side of the platen 129. .

  The driven roller pair 122 includes a driven roller 122a and a pressure roller 122b, and is installed in a state where the respective roller portions are in pressure contact with each other. The driven roller 122a has a larger diameter than the pressure roller 122b, and is attached so that the encoder 128 rotates coaxially. As a result, the driven roller pair 122 is driven and rotated so that the label paper P conveyed by the driven roller 122a is pressed against the pressure-sensitive roller 122b and dragged by the conveyed label paper P. It is rotated. The conveyance speed of the label paper P is detected from sensor information of the encoder 128 that rotates integrally with the driven roller 122a, and the control unit 150 receives the sensor information and executes various control processes.

  The conveyance roller pair 123 includes a conveyance roller 123a and a pressure contact roller 123b, and is installed in a state where the respective roller portions are in pressure contact with each other. A driving belt 125 is wound around the transport roller 123 a together with the drive shaft 124 a of the transport motor 124. The transport roller pair 123 sandwiches the label paper P fed from the paper feed unit 111 between the pressure roller 123b by the transport roller 123a being rotated by the transport motor 124 via the drive belt 125. Carry as you pull it out.

  The paper sensor 127 is arranged on the downstream side of the driven roller pair 122 in the conveyance direction of the label paper P, and detects the leading edge of each label paper P for each label.

  As a result, the conveying unit 121 passes through the platen 129 while holding and positioning the label paper P sent from the paper feeding unit 111 between the driven roller pair 122 and the conveying roller pair 123. It can be conveyed in the direction, carried out of the apparatus and discharged. The leading edge of the temporarily attached label of the label paper P delivered onto the platen 129 can be detected from the sensor information of the paper sensor 127, and the control unit 150 receives the sensor information and executes various control processes. .

  The recording unit 130 includes a recording head 131, a cap 133, a blade 134, and an ink processing system 141, and records and forms image data on a label sheet P that passes over the platen 129 of the sheet unit 110.

  The recording head 131 employs an inkjet recording method, and forms an image on the label paper P by ejecting each color ink in the ink tank 136. The recording head 131 keeps the quality of the ejected ink constant by an ink processing system 141 described later.

  The recording head 131 is installed such that the ink ejection port 132 (see FIG. 2) is formed on the lower surface 131a of the platen 129 facing the label paper P. The recording head 131 moves to a position where the lower surface 131a, which is the formation surface of the ejection port 132, faces the platen 129 (label paper P) and faces it, and ejects granular ink, that is, ink droplets, from the ejection port 132. Then, a recording operation for forming an image on the label paper P is executed.

  In the recording head 131, a plurality of ink ejection ports (nozzles) 132 are aligned so that a paper width direction orthogonal to the conveyance direction A of the label paper P is a nozzle row. That is, the recording head 131 is formed in a so-called full-line head long form that covers the full width of the label paper P as an image forming area.

  Here, the recording head 131 energizes an electrothermal conversion element (heater) installed in an ink flow path communicating with the ejection port 132 to instantaneously generate bubbles, thereby causing ink droplets from the ejection port 132. A so-called thermal method is used to discharge the water. The recording head 131 is not limited to the thermal system, but, for example, a so-called piezoelectric system in which a piezoelectric element (piezo element) that instantaneously changes the capacity of the ink flow path is installed and ink droplets are ejected from the ejection port 132. It goes without saying that may be adopted.

  The recording head 131 includes separate recording heads 131Y, 131M, 131C, and 131K for each color ink of yellow (Y), magenta (M), cyan (C), and black (K). The recording heads 131Y, 131M, 131C, and 131K are arranged in parallel so as to be sequentially arranged from the upstream side in the transport direction A of the label paper P toward the downstream side. Thereby, the recording head 131 discharges and superimposes yellow (Y), magenta (M), cyan (C), and black (K) inks on the one surface side of the label in accordance with the conveyance of the label paper P. A full-color image can be recorded and formed.

  The recording head 131 is cleaned by removing a deposit etc. by wiping the nozzle forming surface 131a and a removable cap 133 covering the lower surface 131a where the ejection port 132 is formed, that is, the nozzle forming surface 131a. A blade 134 is attached.

  The cap 133 is movably supported in the same manner as the recording head 131. The cap 133 is detachably installed by moving to a position facing the nozzle forming surface 131a of the recording head 131. The cap 133 is attached to the nozzle forming surface 131a of the recording head 131, thereby forming a closed space 133s (see FIG. 2) that is in a sealed state on the nozzle forming surface 131a side of the ejection port 132. The cap 133 is arranged in each of the recording heads 131Y, 131M, 131C, and 131K, and is prepared so as to cover the nozzle forming surface 131a side where the discharge port 132 of each color ink is opened. As a result, the cap 133 can avoid unnecessary deposits and promotion of drying as much as possible by blocking the nozzle forming surface 131a of the recording head 131 from the outside air.

  The blade 134 is movably supported in the same manner as the cap 133. The blade 134 is installed to be movable in parallel while moving to a position where it comes into contact with the nozzle forming surface 131a of the recording head 131 and maintaining the contact state. The blade 134 moves in contact with the nozzle forming surface 131a of the recording head 131, thereby wiping off deposits such as residual ink on the nozzle forming surface 131a. The blade 134 is disposed so as to cover the entire nozzle formation surface 131a of each color ink of the recording heads 131Y, 131M, 131C, and 131K. As a result, the blade 134 can keep the nozzle forming surface 131a of the recording head 131 clean, and can prevent the adhering matter such as residual ink from becoming dirty due to rubbing against the label paper P.

  Here, the cap 133 and the blade 134 may be supported by a moving mechanism (not shown) so as to have a common layout for each recording head 131 and moved together to function appropriately. For example, when the cap 133 is attached to the nozzle forming surface 131 a of the recording head 131, the blade 134 enters an adjacent position such as between the recording heads 131 so as not to hinder the attachment of the cap 133. Further, when the blade 134 is translated while being in contact with the nozzle formation surface 131a of the recording head 131, the cap 133 moves down from the nozzle formation surface 131a to the non-contact position and translates, thereby wiping the blade 134. Try not to get in the way. Needless to say, the cap 133 and the blade 134 may be appropriately functioned by being supported by separate moving mechanisms and moved individually.

  The ink tank 136 is prepared for each color ink and installed so as to be positioned above the recording head 131. The ink tanks 136Y, 136M, 136C, and 136K for the respective color inks appropriately supply ink stored in the recording heads 131Y, 131M, 131C, and 131K that are combined corresponding to the ink colors.

  As shown in FIG. 2, the ink tank 136 stores an ink bag 136a that stores ink of the corresponding color. The ink tank 136 applies an elastic force of a spring (not shown) in a spreading direction to the ink bag 136a to generate a negative pressure so that the entire amount of ink flows out and is supplied to the recording head 131 without intrusion of bubbles. It has become. The ink tank 136 is connected via a so-called connection member 137 so that the ink bag 136 a to be stored can supply the ink of the corresponding color to the recording head 131. The ink tank 136 appropriately replenishes the ink in the ink bag 136a via the connection member 137 when the ink in the recording head 131 is consumed in the image forming (printing) operation and the internal pressure decreases. Yes.

  Then, the recording head 131 ejects the ink of the corresponding color replenished from the ink tank 136 into the internal storage tank 131t as ink droplets from the ejection port 132, and forms an image on the label paper P on the platen 129. It has become. In the recording head 131, the ink level in the storage tank 131t is detected by the remaining amount sensor 139, and an instruction to replace the ink tank 136 is appropriately issued from the control unit 150 that has received the liquid level information. . In the recording head 131, after the ink tank 136 is replaced, the ink processing system 141 functions to fill the ink of the corresponding color from the ink tank 136.

  The ink processing system 141 is constructed by connecting a tube 142 to a recording head 131, a cap 133, and the like. The ink processing system 141 is prepared for each color ink in the same manner as the recording head 131 and the ink tank 136.

  In this ink processing system 141, as shown in FIG. 2, a recording tank 131, a cap 133, a buffer tank 143, a tube pump 144, and a waste ink tank 145 can function by various valves via a tube 142. It is connected. The buffer tank 143 to the waste ink tank 145 need not be divided for each color ink, and are connected by a tube 142 so as to be common.

  The buffer tank 143 is connected to the storage tank 131t of the recording head 131 and the cap 133 so as to communicate with each other via a tube 142. The buffer tank 143 is connected to the storage tank 131t of the recording head 131 and the cap 133 by a tube 142 so that the on-off valves 146 and 147 are interposed therebetween, respectively.

  The buffer tank 143 is connected so as to communicate with the waste ink tank 145 through a tube 142 in which a tube pump 144 is interposed. In addition, the buffer tank 143 is provided with an adjustment valve 148 for adjusting the internal pressure. Similarly, the cap 133 is also provided with an adjustment valve 149 that adjusts the internal pressure of the closed space 133 s formed inside when attached to the nozzle forming surface 131 a of the recording head 131.

  The on-off valves 146 and 147 are driven by, for example, a so-called switching solenoid that opens and closes the flow path space in the tube 142 to switch between the communication (open) state and the shut-off (closed) state. The adjustment valves 148 and 149 are driven by, for example, a so-called linear solenoid capable of adjusting the opening area of the flow path space in the tube 142.

  The tube pump 144 is configured to flow in such a manner that the fluid inside is pushed out in one direction by changing the position of crushing the flow path space in the tube 142 in one direction. The tube pump 144 sucks fluid such as internal air and ink from the buffer tank 143 side that can communicate with the storage tank 131t of the recording head 131 and the closed space 133s of the cap 133 so as to flow toward the waste ink tank 145. It has become.

  With this structure, the tube pump 144 closes the opening / closing valve 147 and the regulating valves 148, 149 and opens the opening / closing valve 146, thereby reducing the pressure in the storage tank 131t of the recording head 131 and passing the ink through the connecting member 137. The ink in the tank 136 is filled. The tube pump 144 closes the opening / closing valve 146 and the regulating valves 148, 149 and opens the opening / closing valve 147, thereby reducing the closed space 133s of the cap 133 to the buffer tank 143 from the discharge port 132 of the recording head 131. Ink the ink toward it. The tube pump 144 sucks ink accumulated in the buffer tank 143 by discharging the waste ink tank 145 by closing the on-off valves 146 and 147 and opening the adjusting valve 148.

  As shown in FIG. 3, the control unit 150 includes a controller group including a CPU (Central Processing Unit) 152, an interface group, a memory group such as a ROM (Read Only Memory) and a RAM (Random Access Memory), a sensor group, and the like. It is comprised by. A drive unit including a motor group is connected to the control unit 150 together with the recording head 131 and the like.

  Specifically, the controller group of the control unit 150 includes, for example, a CPU 152, an interface (I / F) controller 153, a motor driving unit 154, and a recording head control circuit 155. The CPU 152 performs overall control of the entire printer 100. The I / F controller 153 executes various communication controls with the CPU 152 and connects to the PC terminal device E so that various data can be exchanged. The motor drive unit 154 controls the drive by executing power supply to the motor group. The recording head control circuit 155 executes various control processes for the recording head 131.

  The interface group includes, for example, an input / output (I / O) port 162, an analog to digital (A / D) converter 163, and an input / output circuit (I / O) 164. The I / O port 162 connects the motor drive unit 154 to the CPU 152 so that various control processes can be realized. The A / D converter 163 connects the CPU 152 to the recording head control circuit 155 to realize driving control of the recording head 131 and transfers the temperature of the recording head 131 detected by the head temperature detection circuit 184 described later to the CPU 152. The input / output circuit 164 connects the CPU 152 so that the detection information of the paper sensor 127 can be acquired.

  The memory group includes, for example, a program ROM 172, a work RAM 173, an EEPROM (Electrically Erasable and Programmable Read-Only Memory) 174, and an image memory 175. The program ROM 172 stores in advance various processing programs such as a control program for overall control of the printer 100 and various parameters used in the processing programs. The work RAM 173 is used as a work area when the CPU 152 executes a processing program. The EEPROM 174 is a rewritable nonvolatile memory, and rewrites and holds various update information such as execution times and execution conditions at the time of various control processes to be described later together with various information unique to the printer 100. For example, the EEPROM 174 stores unique data such as the separation distance between the recording heads 131 and correction values obtained by finely adjusting the image forming position on the label paper P. In the image memory 175, the image data for each color of the image data created by the CPU 152 based on the analysis result of the received command is developed as a bitmap.

  The sensor group includes, for example, a head temperature detection circuit 184 in addition to the paper sensor 127 and the encoder 128. The paper sensor 127 detects the leading edge of the label on the label paper P. The encoder 128 rotates coaxially with the driven roller 122 a of the driven roller pair 122 and outputs a detection signal corresponding to the conveyance speed of the label paper P. The head temperature detection circuit 184 detects the temperature of the recording head 131. That is, the head temperature detection circuit 184 constitutes temperature detection means.

  The motor group of the drive unit includes, for example, a capping motor 192, a head motor 193, a pump motor 194, and a blade motor 195 in addition to the roll motor 114 and the transport motor 124. The capping motor 192 outputs power for moving the cap 133. The head motor 193 outputs power for moving the recording head 131. The pump motor 194 outputs the driving force of the tube pump 144. The blade motor 195 outputs power for moving the blade 134. The conveyance motor 124 outputs the rotational driving force transmitted to the conveyance roller 123a of the conveyance roller pair 123 via the drive belt 125 from the drive shaft 124a. When the roll paper 114 rewinds the label paper P of the paper supply unit 111, the roll motor 114 outputs a power for rotating the paper shaft 112 to reverse the paper.

  Then, the CPU 152 executes a control program stored in the program ROM 172 or the like while using the work RAM 173, and thereby performs overall control of the entire printer 100 such as a drive unit group based on sensor information detected by the sensor group. . Thereby, the CPU 152 develops a bitmap for each color in the image memory 175 for the image data received from the connected PC terminal device E, controls the drive of the recording head control circuit 155, etc., and transfers it to the recording head 131. Thus, an image is formed on the label paper P.

  At this time, the CPU 152 receives the recording data including the image data and a command for instructing the number of sheets, the type, the size, the conveyance speed, and the like, and controls the motor driving unit 154 etc. To form an image. Further, when receiving the recording data, the CPU 152 analyzes the total number of dots as ink ejection conditions, analyzes the conveyance speed, the maximum number of dots per nozzle, and the paper length size in the conveyance direction, The ejection frequency of the recording head 131 is calculated. In addition to analyzing these various commands, the CPU 152 executes arithmetic processing for controlling the entire printer 100 such as reception of recording data, recording operation, and handling of the recording medium.

  In addition, the CPU 152 executes a cleaning operation for cleaning the nozzle formation surface 131a of the recording head 131 and a recovery operation for recovering the ink quality in the ejection port 132 at a preset timing.

  Specifically, the CPU 152 executes an operation of cleaning the nozzle forming surface 131a of the recording head 131 by wiping the nozzle forming surface 131a with the blade 134 by appropriately moving the recording head 131, the cap 133, and the blade 134. Further, the CPU 152 performs an operation of keeping the cleanness by blocking the outside air by attaching the cap 133 to the nozzle forming surface 131a of the recording head 131. In this cleaning process, the CPU 152 adjusts the ink meniscus by preliminarily ejecting a small amount of ink from the ejection port 132 after wiping the nozzle forming surface 131a of the recording head 131 with the blade 134. Further, when a predetermined amount of the preliminarily ejected ink is stored, the CPU 152 sucks it with the tube pump 144 and discharges it to the waste ink tank 145 for disposal.

  In addition, the CPU 152 performs an operation for recovering the quality of the ink in the ejection port 132 in a state where the cap 133 is attached to the nozzle formation surface 131 a of the recording head 131. At this time, the CPU 152 performs the above operation using unique data such as a separation distance between the recording heads 131 stored in the EEPROM 174. The EEPROM 174 stores the execution time and execution conditions of the most recent recovery operation.

  The CPU 152 appropriately performs preliminary discharge recovery, suction recovery, and pressure recovery as the recovery operation of the ink quality in the discharge port 132 of the recording head 131. In the preliminary discharge recovery, a new quality is recovered by preliminarily discharging a small amount of ink from the discharge port 132 in the same manner as the cleaning process of the nozzle forming surface 131a of the recording head 131 by the blade 134 described above. In the suction recovery, the cap 133 is attached to the nozzle forming surface 131a of the recording head 131 and suction is performed by the tube pump 144, whereby the ink in the ejection port 132 is recovered to a new quality. In the pressure recovery, the cap 133 is attached to the nozzle forming surface 131a of the recording head 131 to generate a discharge pressure and pressurize to recover the ink in the discharge port 132 to a new quality. That is, the cap 133 functions as a cap unit, and a recovery unit that performs suction recovery by the cap 133 and the tube pump 144 is configured. Further, the recovery means for executing preliminary discharge recovery is configured by the ink discharge function of the recording head 131, and the recovery means for executing pressure recovery is configured by the ink discharge function of the recording head 131 and the cap 133.

  Here, the suction recovery is executed by attaching the cap 133 to the recording head 131 and sucking the ink in the ejection port 132 to the buffer tank 143 whose inside is in a reduced pressure state. Specifically, a cap 133 is attached to the nozzle forming surface 131a of the recording head 131 so that all of the on-off valves 146 and 147 and the regulating valves 148 and 149 are closed, and the buffer pump 143 is sucked by the tube pump 144. The inside is decompressed. Thereafter, by opening the on-off valve 147, the ink in the ejection port 132 of the recording head 131 is sucked and recovered to a new quality. This suction pressure can be adjusted by the number of rotations of the tube pump 144.

  Meanwhile, when ink droplets are ejected from the ejection ports 132 of the recording head 131, the printer 100 generates droplets of ink, so-called ink mist, which adheres to the nozzle formation surface 131a and is dried. When the cap 133 is attached to the recording head 131 with the dried ink mist attached, the space (closed space 133 s) formed between the recording head 131 and the nozzle forming surface 131 a is blocked from the outside. Then, in the recording head 131, the equilibrium of the evaporation component proceeds between the dried ink mist in the closed space 133s and the ink in the ejection port 132, and the viscosity of the ink in the ejection port 132 increases. Thus, the above-described recovery process is required.

  From this, the CPU 152 acquires the mist adhesion state such as the ink mist adhesion amount and the drying information on the nozzle forming surface 131a of the recording head 131, determines whether or not the recovery operation is necessary, and determines whether or not the recovery operation is necessary. A control process for restoring the ink to a new ink quality is executed. That is, the CPU 152 constitutes a control means.

  Specifically, the CPU 152 performs control processing for executing the above-described various operations based on the control program. At this time, the CPU 152 collects and acquires various types of information to perform optimal operations under optimal conditions. It is supposed to run.

  For example, the CPU 152 obtains the count by a counter function including an exposure time in which the nozzle forming surface 131a of the recording head 131 is exposed to the outside air with the cap 133 removed. In addition, the CPU 152 similarly counts and acquires the elapsed time (hereinafter, also simply referred to as pause time) in the pause state of the recording head 131 that is left with the cap 133 attached. Further, when performing a recording operation for forming an image on the label paper P, the CPU 152 acquires ink droplet ejection conditions from the ejection ports 132 of the recording head 131. That is, the CPU 152 acquires the exposure time of the nozzle forming surface 131a of the recording head 131 and the rest time of the recording head 131 as ink mist drying information (mist adhesion state).

  The CPU 152 first executes a determination processing procedure (method) shown in the flowchart of FIG. 4, for example, to determine the ink mist fixing level on the nozzle forming surface 131 a of the recording head 131.

  First, when confirming the reception of image data (recording data) from the PC terminal device E (step S101), the CPU 152 analyzes the total number of dots D counted in the image data (step S102).

Next, the CPU 152 analyzes the transport speed V (mm / sec) of the label paper P, the maximum number of dots d per nozzle of the ejection port 132, and the paper unit length L (mm) in the transport direction from the print data, and the print head. The ink droplet ejection frequency f 131 is calculated from the following equation (step S103).
Discharge frequency f = (conveying speed V × maximum number of dots d) / paper unit length L

  Next, when the cap 133 is removed from the recording head 131, the CPU 152 stops counting (measuring) the pause time t2, writes it in the EEPROM 174, and holds it (step S104). At the same time, the CPU 152 starts (restarts) counting of the exposure time t1 of the nozzle forming surface 131a after execution of the recovery operation and the cleaning operation of the previous recording head 131 from the count value in the EEPROM 174 (step S105). Here, when the cap 133 is attached immediately after the above-described recovery operation or the like is performed on the nozzle forming surface 131a of the recording head 131, the count is started after the exposure time t1 is reset.

  Next, the CPU 152 starts an image forming operation on the conveyed label paper P (step S106), ends the image forming process of the received image data on the label paper P, and attaches the cap 133 to the recording head 131. A series of operations such as these are completed (step S107).

  Next, the CPU 152 acquires the maximum temperature T of the recording head 131 from the sensor information of the head temperature detection circuit 184 (step S108). In this embodiment, the case where the maximum temperature T of the recording head 131 is used will be described as an example. However, the present invention is not limited to this. For example, an average temperature during a recording operation may be used.

  Next, the CPU 152 stops counting the exposure time t1 of the nozzle forming surface 131a of the recording head 131 and writes and holds it in the EEPROM 174 (step S109). At the same time, the CPU 152 starts (restarts) counting the pause time t2 with the cap 133 of the recording head 131 attached (step S110).

  Next, the CPU 152 refers to the ejection frequency f acquired in steps S103 and S108 and the maximum temperature T of the recording head 131, and determines the ease of occurrence of ink mist during the image forming operation from the table (list) shown in FIG. A mist generation coefficient α is determined (step S111). Here, when the temperature of the recording head 131 is high, the ink temperature is also high and the ink viscosity is low. Therefore, splashing is likely to occur with the ejection of ink droplets, and the amount of ink mist generated increases. There is a tendency. In addition, when the ink ejection frequency f is high, the so-called refilling insufficiency that the ink filling up to the front end side of the ejection port 132 of the recording head 131 is not in time easily occurs. When this refill is insufficient, the ejection speed increases with a decrease in the ejection amount of the ink droplets, so that splashing is likely to occur and the amount of ink mist generation tends to increase. The mist generation coefficient α shown in FIG. 5 varies depending on the common liquid chamber capacity of the recording head 131, the number of nozzles of the discharge ports 132, the heat dissipation structure, and the like, and basically depends on the device specifications of the printer 100. The coefficient α in the present embodiment is just an example as a value indicating a tendency. In the present embodiment, the case where the mist generation coefficient α is determined from the table of FIG. 5 will be described as an example. However, the present invention is not limited to this. The list is used as a map, and an intermediate value of the coefficient α is determined. You may calculate by calculation. The table is used as a map in this way even when the table of FIG. 8 is used.

  Note that the temperature of the recording head 131 is used in the present embodiment in order to improve accuracy in estimating the amount of mist generated. As the ejection frequency f increases, the temperature of the recording head 131 increases. Therefore, it is possible to calculate the mist amount only from the discharge frequency f.

Next, the CPU 152 calculates the ink mist amount m generated in the image forming operation from the following equation using the mist constant β in addition to the total number of dots D and the mist generation coefficient α in steps S102 and S111 (step S102). S112). Here, the mist constant β is not particularly shown, but for each type such as ink color, the common liquid chamber capacity of the recording head 131, the number of nozzles of the discharge port 132, the heat dissipation structure, etc., as with the mist generation coefficient α. Basically, values that depend on the device specifications of the printer 100 are used.
Ink mist amount m = total number of dots D × mist generation coefficient α × mist constant β

For example, when the ink droplet ejection frequency f is 2.4 kHz and the maximum temperature T of the recording head 131 is 38 ° C., the ink mist generation coefficient α is multiplied by 1.0 by the mist constant β to obtain the ink mist amount m. 1.2 × 10 ⁻² cc is calculated.

  Next, the CPU 152 calculates a cumulative amount (attachment amount) M of the ink mist amount m calculated in step S112 (step S113).

  Next, the CPU 152 confirms whether or not there is a shutdown command for shifting to the sleep (standby) state or turning off the power after the image forming operation is completed (step S114). Go back to and repeat the same process.

  In step S114, the CPU 152 that has confirmed the sleep state or the shutdown command acquires the exposure time t1 that has been stopped in step S109 (step S115).

  Next, the CPU 152 determines (estimates) the mist fixing level from the table shown in FIG. 6 on the basis of the exposure time t1 and the ink mist cumulative amount M calculated in step S113, and writes and stores it in the EEPROM 174 (step). S116). Here, when the accumulated amount (attachment amount) M of the mist attached to the nozzle forming surface 131a of the recording head 131 is small and the exposure time t1 is also short, the amount of fixation after evaporation of moisture is small and the fixation level is low. There is a tendency. On the other hand, when the accumulated amount M of mist is large and the exposure time t1 is also long, the amount of fixing after evaporation of water is large and the fixing level tends to be high. Therefore, in the table of FIG. 6, the higher the accumulated mist amount M and the longer the exposure time t1, the lower the fixing level C to the intermediate fixing level B, and the higher fixing level A. The higher the fixing level is, the larger the number A is set to the fixing level AAA. In short, the fixing level increases in the order of C <B <A <AA <AAA. Note that the table of FIG. 6 is merely an example, and needless to say, it may be set as appropriate.

  The CPU 152 performs the above-described recovery operation of the recording head 131 as one of the initialization operations when returning from the sleep state or when the power is turned on to enter the operation state. For example, the suction recovery control process shown in the flowchart of FIG. Perform procedures (methods) as appropriate. As a result, this initialization operation is always executed at the start of work and the like, and whether or not the above-described recovery operation is necessary is appropriately determined and executed.

  First, the CPU 152 starts an initialization operation, and acquires a pause time t2 in which the cap 133 of the recording head 131 is attached (step S201).

  Next, it is confirmed whether or not the suspension time t2 is 24 hours (h) or longer (step S202). If it is confirmed that the suspension time t2 is not longer, the process is terminated and the next initialization is performed. The same processing is repeated for each operation.

  Further, the CPU 152 confirming the rest time t2 of 24 hours or more in step S202 reads out and acquires the mist fixing level determined in step S116 from the EEPROM 174 (step S203).

  Next, the CPU 152 determines the suction pressure by the tube pump 144 from the table shown in FIG. 8 based on the acquired pause time t2 of the recording head 131 and the mist fixing level (step S204).

  Here, when left for a long time in a state where the amount of accumulated mist M to be fixed is large, the humidity in the closed space 133 s between the cap 133 and the nozzle forming surface 131 a of the recording head 131 is balanced, and the fixation mist However, a lot of moisture is taken away from the ink in the ejection port 132. Then, the viscosity increase of the ink in the ejection port 132 is promoted. In order to remove the thickened ink and restore it to a new ink quality, a strong nozzle suction pressure is required. Therefore, in the table of FIG. 8, the accumulated mist amount M to be fixed is large, in other words, the higher the fixing level and the longer the pause time t2, the lower suction pressure to the middle suction pressure are sandwiched. The suction pressure is set to be high. Note that the table in FIG. 8 is merely an example, and needless to say, it may be set as appropriate.

  Next, after executing the suction recovery operation with the suction pressure determined in step S204 (step S205), the CPU 152 calculates the accumulated mist amount M stored in the EEPROM 174, the exposure time t1 and the rest time t2 of the recording head 131. Reset (step S206).

  As a result, the ink in the ejection port 132 of the recording head 131 is appropriately suction-recovered even when the evaporated moisture is removed by the ink mist that adheres to the nozzle forming surface 131a and dries, and the viscosity increases. And restored to the new ink quality. At this time, a 24-hour rest time t2 of the recording head 131 is confirmed, and a suction recovery operation with a suction strength according to the accumulated mist amount M and the exposure time t1 is executed.

  As described above, in the printer 100 of the present embodiment, the recovery operation of the set number of suction times and the set suction amount that is more than necessary is mechanically executed to avoid wasting ink, and the ink can be appropriately used. A quality recovery operation can be performed. At this time, the ink quality recovery operation can be executed with the optimum suction strength according to the accumulated amount M of the ink mist and the mist adhesion state at the exposure time t1, and it is possible to maintain high ejection quality (ejection performance). it can.

  Here, in the present embodiment, the suction recovery process is executed when the pause time t2 exceeds 24 hours. However, the present invention is not limited to this. For example, according to the value of the cumulative mist amount M and the exposure time t1. It may be executed as appropriate at the optimum timing. In this case, the recovery operation can be appropriately executed even when a large amount of ink mist or operation time is long and drying is progressing.

  In this embodiment, a case where the suction recovery is performed as an ink quality recovery operation in the ejection port 132 of the recording head 131 is described as an example, but the present invention is not limited to this. For example, the preliminary discharge recovery and the pressure recovery may be executed instead of or in combination with the suction recovery, and further, the cleaning operation using the blade 134 may be combined.

  In the present embodiment, the recovery operation according to the ink mist adhering to the recording head has been described. However, due to the influence of water vapor generated during the recording operation, condensation may occur and adhere to the recording head. When the recording head is capped in a state where condensation has occurred, the moisture in the cap tends to be maintained because the condensed moisture re-evaporates in the cap. Therefore, you may set the kind of recovery operation | movement performed with the state of dew condensation. The occurrence of condensation can be determined from the temperature and humidity in the machine and the number of dots to be recorded.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

100: Printer 131, 131Y, 131M, 131C, 131K ... Recording head 131a ... Nozzle formation surface (lower surface)
132 …… Discharge port 133 …… Cap 133s …… Closed space 134 …… Blade 136, 136Y, 136M, 136C, 136K …… Ink tank 141 …… Ink processing system 142 …… Tube 143 …… Buffer tank 144 …… Tube Pump 145 ... Waste ink tank 146, 147 ... On-off valve 148, 149 ... Adjusting valve 152 ... CPU
154... Motor drive unit 155... Print head control circuit 172.
174 …… EEPROM
184: Head temperature detection circuit E: PC terminal device P: Label paper

Claims (7)

A recording head that forms an image on a recording medium by discharging ink from the discharge port;
Recovery means for performing a recovery operation to recover the discharge performance of the discharge port;
Control means for controlling the recovery operation performed by the recovery means based on the adhesion state of the ink attached to the formation surface of the ejection port;
An ink jet recording apparatus comprising:   2. The inkjet recording apparatus according to claim 1, wherein the control unit controls the recovery unit based on at least a frequency at which ink is ejected from the recording head during recording.   2. The control unit according to claim 1, wherein the control unit controls the recovery unit based on at least one of an exposure time of the forming surface of the discharge port to the outside air and a pause time of the recording operation. The ink jet recording apparatus according to claim 2. The recovery means includes a cap unit that is attached to a forming surface of the discharge port so that the discharge port is hermetically sealed and ink discharge performance can be recovered by sucking ink from the discharge port. ,
4. The ink jet recording apparatus according to claim 1, wherein the control unit adjusts a suction pressure of ink from the ejection port by the recovery unit. 5. A recording head that discharges ink from an ejection port to form an image on a recording medium;
Cap means for sealing the discharge port in contact with the periphery of the discharge port;
Recovery means for performing a recovery operation to recover the discharge performance of the discharge port;
When the cap unit performs the recovery operation based on the duration time during which the discharge port is kept in the sealed state, the cap unit removes the discharge port from the discharge port at the time of image formation immediately before setting the discharge port in the continuous sealed state. Control means for causing the recovery means to perform a recovery operation to vary the amount of ink discharged from the discharge port in accordance with the ink discharge frequency;
An ink jet recording apparatus comprising: Temperature detecting means for detecting the temperature of the recording head during image formation;
In the image formation immediately before the cap unit seals the ejection port, the control unit performs a recovery operation in which the recovery unit increases the amount of ink discharged from the ejection port as the temperature detected by the temperature detection unit increases. The ink jet recording apparatus according to claim 5, wherein the recovery means is performed. An ink discharge quality recovery method executed in an ink jet recording apparatus, comprising: a recording head that discharges ink from discharge ports to form an image on a recording medium; and a recovery unit that recovers the discharge performance of the discharge ports.
An ink discharge quality recovery method for an ink jet recording apparatus, comprising: acquiring an adhesion state of ink adhering to a formation surface of the ejection port, and controlling a recovery operation performed by the recovery unit based on the adhesion state.

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