JP2006224420A - Liquid delivering device and recovering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid delivering device which carries out a suitable recovery action, and to provide a recovering method for performing the recovery action. <P>SOLUTION: According to the recovering method, when the liquid delivering face is sealed with a cap member, a humidity in a sealed space is detected, and a recovery action mode is selected based on the detected humidity. Specifically, if the detected humidity is in a high humidity (90% or more) state, the device carries out a preliminary delivering action. On the other hand, if the detected humidity is in a low humidity state of less than 90%, an elapsed time from a last delivering or from a last recovery action is taken into consideration. That is, if the elapsed time is short, the device carries out the preliminary delivering, whereas if the elapsed time is long, a normal or strong sucking action is carried out. In this manner, the suitable recovery action that reflects a dry state inside nozzles with high accuracy, is carried out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid ejecting apparatus that performs drawing by ejecting liquid, such as an ink jet recording apparatus, a display manufacturing apparatus, an electrode forming apparatus, or a biochip manufacturing apparatus, and a recovery method thereof.

Conventionally, inkjet printers suitable for printing on paper have been known as liquid ejection devices, and in general, liquid (ink) is ejected from minute nozzles onto a carriage that reciprocates in the paper width direction of printing paper. It is the structure which mounts the discharge head which performs.
Such a liquid discharge apparatus has a specific problem due to handling of liquid, one of which relates to the deterioration of the liquid over time in the flow path in the discharge head, particularly in the flow path around the nozzle. . In other words, during non-operation, the liquid (ink) moisture evaporates through the nozzle opening, resulting in an increase in viscosity, etc., and a decrease in ejection performance when operation is resumed (non-ejection, flight speed reduction of ejected droplets, etc.) May affect. Of course, the liquid ejection device is equipped with a cap member that seals the nozzle opening during non-operation and protects it from drying, etc. It is not possible.

  In view of the above-mentioned problems, prior to discharge onto printing paper or the like, preliminary discharge (preliminary discharge operation) for discarding deteriorated liquid is performed, or when the liquid is significantly dried, the liquid is There is known a liquid ejecting apparatus that performs so-called recovery operation that forcibly suctions from an opening (suction operation). For example, the liquid ejection device according to Patent Literature 1 is configured to select whether to perform a preliminary ejection operation or a suction operation based on a non-operation time, and to select a condition in each operation, and to perform a recovery operation The liquid disposal amount and the operation time are optimized.

JP 2000-289229 A

  However, the liquid ejection device according to Patent Document 1 determines various conditions of the recovery operation based on the non-operation time, and it is difficult to say that the recovery operation is adequately optimized. This is because the conditions for drying the liquid through the nozzle opening vary depending on, for example, the surrounding environment in which it is installed and the amount of liquid initially remaining in the cap before the nozzle opening is sealed. is there.

  SUMMARY An advantage of some aspects of the invention is to provide a liquid ejection apparatus that performs a more appropriate recovery operation and a recovery method related to the recovery operation.

The present invention includes a nozzle for discharging a liquid, and performs a recovery operation for discharging the liquid from the nozzle to the outside of the discharge object prior to a drawing operation for discharging the discharge object. A capping unit capable of sealing the nozzle opening; and a humidity detection unit configured to detect humidity in a space facing the nozzle opening in a state where the nozzle opening is sealed by the capping unit; And a condition selection means for detecting the humidity of the space prior to the recovery operation and selecting a condition for the recovery operation based on the humidity.
Preferably, the liquid ejection apparatus includes a suction unit that sucks the liquid from the nozzle, and performs the recovery operation using the suction unit.
Preferably, the liquid ejection device performs the recovery operation by a preliminary ejection operation for ejecting the liquid to the outside of the ejection target.
Preferably, the liquid discharge apparatus is characterized in that the liquid discharge amount in the recovery operation changes according to a condition selected by the condition selection unit.

  In the liquid ejection apparatus according to the present invention, the humidity of the space sealed by the capping unit is detected, and based on the detection result, the condition selection unit selects a recovery operation suitable for the progress of liquid drying inside the nozzle. To do. That is, it is possible to effectively optimize the recovery operation based on the humidity of the sealed space showing a high correlation with the dry state of the liquid inside the nozzle. As a result, it is unlikely that wasteful liquid or time is consumed in the suction operation when the drying is not progressing, and sufficient recovery cannot be achieved when the drying is progressing. The convenience is excellent. Further, it is preferable that a strong and reliable recovery operation can be selected by the suction operation using the suction means, and a simple recovery operation can be selected by the preliminary discharge operation, so that more appropriate operation can be achieved. Preferably, such optimization is achieved by changing the discharge amount (suction amount, number of discharges, etc.) related to the recovery operation.

  Further, in the liquid ejection apparatus, the condition selection unit acquires a substantial elapsed time from the discharge of the liquid immediately before the recovery operation prior to the recovery operation, and the elapsed time and the detected humidity The condition of the recovery operation is selected based on the above.

  According to the liquid ejection apparatus of the present invention, it is possible to know the substantial drying time for the liquid to be discharged by the recovery operation by acquiring the elapsed time. This elapsed time is an important factor that represents the degree of progress of drying of the liquid inside the nozzle together with the humidity detected by the humidity detecting means, so that a more appropriate recovery operation can be performed by considering the elapsed time. it can.

In the liquid ejection apparatus, the suction unit seals the opening of the nozzle by the capping unit, and performs a suction operation of sucking the liquid from the nozzle by reducing the sealed space. Features.
In the liquid ejection apparatus according to the present invention, since the suction unit is configured using the capping unit, the number of components can be reduced.

Further, in the liquid ejecting apparatus in which the capping means constitutes the suction means, the humidity detection means is disposed in the vicinity of the nozzle opening and can be sealed together with the nozzle opening by the capping means. It is characterized by.
Preferably, the capping unit seals the opening of the nozzle without including the humidity detecting unit when the suction operation is performed.
More preferably, the capping unit is a cap member that can be sealed around a certain region of the discharge surface where the nozzle opening is formed, and the discharge surface is formed with the nozzle opening. A nozzle region; a detection region in which the humidity detection unit is disposed adjacent to the nozzle region; and a dummy region that is a region facing the detection region across the nozzle region. It is characterized by.
More preferably, the humidity detecting means is disposed in a recess formed in the ejection surface.

When the humidity detecting means is disposed in the capping means, the humidity detecting means will come into contact with the liquid every time the suction operation is performed, leading to a failure of the humidity detecting means, or the liquid adhering to the humidity detecting means. Due to the influence, the humidity around the nozzle opening may not be detected accurately.
According to this liquid ejecting apparatus, the humidity detecting means is disposed in the vicinity of the nozzle opening, and the humidity in the vicinity of the opening can be detected by sealing the capping means together with the opening. By sealing the nozzle opening without including the humidity detection means, it is possible to avoid the humidity detection means from coming into direct contact with the liquid. In addition, such a configuration can be easily realized by a cap member that can be sealed around a certain region of the discharge surface, and a discharge surface including a nozzle region, a detection region, and a dummy region. Further, at this time, if the humidity detecting means is disposed in the recess formed on the discharge surface, the entire discharge surface can be made a smooth surface, so that the maintenance of the discharge surface is easy.

  The present invention provides a recovery method that is performed prior to a drawing operation for discharging the discharge target object in a liquid discharge apparatus including a nozzle for discharging liquid to the discharge target object. A humidity detecting step of detecting the humidity of the sealed space in a state where the nozzle opening is sealed by the capping means prior to the discharging step, the discharging step including discharging the liquid out of the discharge target And a condition selection step of selecting a condition for the discharge step based on the humidity detected in the humidity detection step.

  According to the recovery method of the present invention, the humidity of the space sealed by the capping means is detected, and it is determined whether or not the suction operation needs to be performed based on the detection result. Therefore, it is possible to perform a more suitable recovery operation, and the reliability and the convenience for the user are excellent.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
Note that the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

(Overall configuration of liquid ejection device)
First, the configuration of the liquid ejection apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a schematic perspective view showing an example of a liquid ejection apparatus according to the present invention.
In FIG. 1, a printer 1 as a liquid ejection apparatus is an apparatus that draws an image or the like by ejecting ink as a liquid onto the surface of a sheet 2 as an ejection target. The illustrated printer 1 includes an ejection head 3 that ejects ink, a carriage 4 to which the ejection head 3 is attached, a carriage moving mechanism 5 that moves the carriage 4 in the main scanning direction, and a platen roller that transports the paper 2 in the sub-scanning direction. 6 etc.

For example, four colors of black, magenta, cyan, and yellow are used as ink ejected from the ejection head 3, and each is accommodated in ink cartridges 7 a to 7 d mounted on the carriage 4. At the bottom of the ink cartridges 7a to 7d, a lead-out portion (not shown) for leading out ink is provided, and coupled to an ink introduction portion (not shown) provided on the discharge head 3, Ink is supplied to the printer.
The carriage moving mechanism 5 includes a timing belt 8. The timing belt 8 is driven by a motor 9 such as a DC motor. That is, when the motor 9 is driven to rotate, the carriage 4 is guided by the guide rod 10 installed on the printer 1 and reciprocates in the main scanning direction (extension direction of the guide rod 10).
In the above-described configuration, the ejection head 3 is moved relative to the paper 2 in the main scanning direction and the sub-scanning direction, and ink is appropriately supplied from the nozzle openings 23 (see FIG. 2) formed on the ejection surface 13 of the ejection head 3. By discharging, ink droplets are landed on a desired position on the paper 2 to form an image.

A maintenance mechanism 12 as a suction unit is disposed at a home position that is a non-recording area of the printer 1. The maintenance mechanism 12 includes a cap member 15 as a capping unit that can be sealed around a certain region of the ejection surface 13 of the ejection head 3. The cap member 15 is a box-shaped elastic member whose surface facing the discharge surface 13 is open, and is in close contact with the discharge surface 13 to seal the nozzle opening 23 (see FIG. 2) (capping operation). Maintenance of the nozzle opening 23 can be achieved. The cap member 15 is also used for a suction operation described later.
The maintenance mechanism 12 also has a wiper blade 14 that is a plate-like member formed of an elastomer or the like. When the edge of the wiper blade 14 slides relatively on the discharge surface 13, the discharge surface 13 is wiped off, and a so-called winding operation is performed.

(Discharge head configuration)
Next, the configuration of the ejection head will be described with reference to FIG. FIG. 2 is a schematic perspective view of the ejection head.
In FIG. 2, the discharge head 3 has, as its appearance, a base member 20 made of hard resin or the like, a discharge surface 13 on which nozzle openings 23 are formed, and a cover member 21 formed by pressing SUS or the like. A rivet 22 for attaching the cover member 21 to the base member 20 and a connection terminal portion 24 for electrical connection with the printer main body via a flexible cable are provided. In addition, an ink introduction portion (not shown) that receives ink supply from the ink cartridges 7a to 7d is provided on the back side of the ejection head 3 (not shown).

Inside the ejection head 3, a minute flow path branched in communication with an ink introduction portion (not shown) is formed, and the nozzle opening formed on one end side of the flow path is the nozzle opening 23. . Further, pressure generating means 38 (see FIG. 4) such as a piezo element is provided in the vicinity of each nozzle in the flow path. Then, when the pressure generating means 38 (see FIG. 4) is driven by the electric signal input through the connection terminal portion 24, the ink in the nozzle is pushed out by the generated pressure, and the pushed out ink passes through the nozzle opening 23. It is designed to be discharged.
The cover member 21 serves to protect the discharge surface 13 by relaxing the contact between the discharge surface 13 and the wiper blade 14 (see FIG. 1) in the wiping operation. Further, it also serves as a ground terminal via the connection terminal portion 24 so that static electricity is not charged in the ejection head 3.

The nozzle openings 23 are arranged in a four-row linear array in a nozzle region 27 occupying the vicinity of the center of the ejection surface 13. Each column corresponds to each of the four colors of ink.
The discharge surface 13 has a detection area 28 adjacent to the nozzle area 27 and provided with a humidity sensor 26 as humidity detection means. The humidity sensor 26 is disposed in a recess 25 formed on the ejection surface 13 and can detect the humidity near the nozzle opening 23. Then, the measured humidity information can be transmitted as an electrical signal to the printer main body via the electrical wiring routed in the base member 20 and the connection terminal portion 24. As the humidity sensor 26, for example, a sensor that measures humidity from a change in dielectric constant or resistivity of a wet and dry material is used. The type is classified into a polymer type, a ceramic type, an electrolyte type, etc. depending on the wet and dry materials, but it is a small one with a size of about several square millimeters, and a type suitable for measurement in a high humidity range of 40 to 100% is selected. It is preferable.
On the ejection surface 13, a portion facing the detection region 28 across the nozzle region 27 is a dummy region 29 having a width corresponding to the detection region 28. The dummy area 29 exposes the discharge surface 13 and is not provided with anything, but plays an important role in the suction operation described later.

(Capping operation, suction operation, preliminary discharge operation)
Next, a capping operation, a suction operation, and a preliminary discharge operation will be described with reference to FIG. FIG. 3A is a cross-sectional view showing the relationship between the ejection head and the maintenance mechanism related to the capping operation. FIG. 3B is a cross-sectional view showing the relationship between the discharge head and the maintenance mechanism related to the suction operation.
First, prior to the description of each operation, a supplementary description is given of the overall configuration of the maintenance mechanism 12. As shown in FIG. 3, the maintenance mechanism 12 includes a cap member 15 that can be moved in the vertical direction of the drawing by a mechanism (not shown), a tube 30 that communicates with the through hole 15 c formed in the inner bottom portion 15 b of the cap member 15, A suction pump 31 provided in the middle of the tube 30, a waste liquid storage portion 33 that stores one end of the tube 30 opposite to the cap member 15, and a wiper blade 14 are provided. The suction pump 31 is a so-called tube pump that sends ink and air by crushing and squeezing the tube 30, and can suck ink and air in the cap member 15 through the through hole 15 c. In the cap member 15, a liquid absorbing material 34 formed of a liquid absorbing material such as sponge is accommodated.

In the capping operation, the carriage 4 is moved to a position shown in FIG. 3A (hereinafter referred to as a capping position), and the seal portion 15a of the cap member 15 is brought into close contact with the ejection surface 13, so that the nozzle region 27 and the detection region are detected. 28 is sealed. Thus, since the detection region 28 is sealed together with the nozzle region 27 by the cap member 15, the humidity of the space 35 facing the nozzle opening 23 can be appropriately detected by the humidity sensor 26.
The printer 1 (see FIG. 1) is in the state shown in FIG. 3A when waiting for a print command or when the main power is turned off, and this state will be referred to as a capping state below. Call it. In this capping state, the space 35 where the nozzle opening 23 faces is substantially a closed space, so that it is possible to suppress water evaporation of ink from the nozzle opening 23 to some extent. In particular, when the liquid absorbing material 34 is provided in the cap member 15 as in this embodiment, the space 35 is maintained in a high humidity state by the ink stored in the liquid absorbing material 34, and a high moisture retention effect is achieved. Obtainable.

  However, even though the nozzle opening 23 is sealed by the cap member 15, for example, slight ventilation may occur through the wall surface of the tube 30. The water evaporation of ink proceeds gradually. The printer 1 (see FIG. 1) uses the suction operation and preliminary discharge operation described below to remove the dried ink inside the nozzles in case the ink inside the nozzles is dried and cannot be properly discharged. A so-called recovery operation of forcibly discharging is performed. This recovery operation is appropriately performed according to the degree of progress of ink drying by detecting the humidity described above (details will be described later).

  In the suction operation, first, as shown in FIG. 3B, the carriage 4 is moved to a position slightly to the left (hereinafter referred to as a maintenance position) from the capping position (see FIG. 3A). The seal portion 15 a of the cap member 15 is brought into close contact with the discharge surface 13. At this time, the nozzle region 27 and the dummy region 29 are sealed by the cap member 15, and the detection region 28 is open. When the suction pump 31 is driven from this state, the space 35 is depressurized and ink is forcibly discharged from the nozzle opening 23, and the discharged ink is stored in the waste liquid storage unit 33 as waste liquid. That is, the cap member 15 functions as a capping unit that seals the nozzle opening 23 and constitutes a suction unit that sucks ink from the nozzle opening 23. By using such a unit in common, the number of parts can be reduced. I am trying.

In the course of the suction operation, the ink discharged from the nozzle opening 23 into the cap member 15 is once filled in the entire space 35. For this reason, after the suction operation, the nozzle area 27 and the dummy area 29 on the ejection surface 13 are wetted with ink. Here, if the periphery of the nozzle opening 23 remains wet, it causes a discharge failure during a printing operation (drawing operation). Therefore, after the suction operation, the discharge surface 13 is wiped by a wiping operation, The wet ink in the nozzle area 27 is removed.
On the other hand, in the suction operation, the detection region 28 including the humidity sensor 26 is open to the outside of the cap member 15 as shown in FIG. For this reason, the humidity sensor 26 breaks down, or in the capping state shown in FIG. 3A, the humidity of the space 35 cannot be correctly detected due to the influence of wet ink or solidified ink. There is no problem. As can be seen from this description, the dummy region 29 is provided as a close contact region with the seal portion 15a of the cap member 15 in view of the sealing position in the suction operation.

  The wiping operation is performed by moving the cap member 15 downward from the state of FIG. 3B to open the discharge surface 13 and moving the carriage 4 to the left. As a result, the edge of the wiper blade 14 slides relatively on the ejection surface 13 and the ink on the ejection surface 13 is scraped off. At this time, since the humidity sensor 26 in the detection area 28 is disposed in the recess 25 formed on the discharge surface 13, the entire discharge surface 13 is configured as a single flat surface, and the wiping operation can be performed without hindrance. it can. Further, the relative movement direction of the ejection surface 13 and the wiper blade 14 is also taken into consideration so that the scraped ink does not collect in the recess 25, and the detection area 28 is on the upper side. The wiper blade 14 moves away from the paper surface when not in use, and deviates from the movement track of the ejection surface 13.

  The preliminary ejection operation is performed by ejecting ink into the cap member 15 in a state where the ejection head 3 is moved to the maintenance position (see FIG. 3B) and the seal portion 15a is not in close contact with the ejection surface 13. It is. The reason why the preliminary ejection operation is performed at the maintenance position is to prevent the ejected ink from being bounced off by the inner wall of the cap member 15 to contaminate the humidity sensor 26.

The preliminary discharge operation is used for various purposes. First, the first purpose is a simple recovery operation, and when the ink that has been dried in the nozzle can be sufficiently discharged by the discharge operation without performing the forced discharge by the suction operation, the cap member 15 is thus provided. The ejection performance is recovered by ejecting ink.
The second purpose is that when the cap member 15 is filled with ink by the suction operation, the ink once discharged from the nozzle may flow backward from the cap member 15 to the inside of the nozzle. It is to discharge such a backflowed ink. That is, when the suction operation is performed, the preliminary discharge operation is generally performed together.
The third purpose is to supply moisture into the cap member 15 to enhance the moisture retention capacity of the space 35 in the capping state.
In the case of the first and second purposes described above, the preliminary ejection may not be performed in the cap member 15 but may be performed in a dedicated waste ink area.

(Electrical configuration of printer)
Next, the electrical configuration of the printer will be described with reference to FIG. FIG. 4 is a block diagram showing the electrical configuration of the printer.
The printer 1 includes a control unit 60, and the control unit 60 is electrically connected to the motor 9, the suction pump motor 39, and the discharge head 3 described above. The control unit 60 receives command codes and print data of various operation commands from the host computer 63 via the interface 62, and controls the printing operation (drawing operation) and the recovery operation. ing.

  During the printing operation, the controller 60 drives the motor 9 and a motor (not shown) that drives the platen roller 6 (see FIG. 1) to scan the carriage 4 (see FIG. 1) and the paper 2. The ejection control for each nozzle of the ejection head 3 is performed in synchronization with the scanning. Specifically, first, the ejection control unit 61 generates an ON / OFF signal (hereinafter referred to as a data signal) for each nozzle synchronized with the scanning position based on the print data sent from the host computer 63. . Then, this data signal is sent to a switching element (not shown) formed for each nozzle, and the application of the drive signal generated by the drive signal generating circuit 64 to the pressure generating means 38 is switched.

The recovery operation includes an operation that is appropriately executed by a user's operation and an operation that is automatically performed prior to a printing operation (drawing operation) (automatic recovery operation), but both mechanism operations are common. That is, under the control of the control unit 60, the motor 9 is driven to move the carriage 4 to the maintenance position (see FIG. 3B), and the suction pump motor 39 is driven to perform the suction operation. Alternatively, the motor 9 is driven to move the carriage 4 to the maintenance position (see FIG. 3B), and the preliminary discharge operation is performed by the discharge control of the discharge control unit 61.
In the recovery operation, a plurality of modes are prepared in which the rotation speed and rotation amount of the suction pump motor 39 in the suction operation, or the drive signal mode and the number of discharges in the preliminary discharge operation are different. The information is stored in the storage unit 67. In particular, in the automatic recovery operation, the mode selection unit 65 performs an optimal recovery based on the humidity detected by the humidity sensor 26 of the ejection head 3 and the elapsed time (details will be described later) acquired from the elapsed time management unit 66. Select an action. That is, the control unit 60 is a condition selection unit in the present invention.

(Flow related to printing operations)
Next, a series of flows from the standby state to the standby state through the printing operation will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the printing operation.
When a print command is input from the host computer 63 to the control unit 60, the control unit 60 determines whether or not an automatic recovery operation is required (step S1 in FIG. 5). Here, when the automatic recovery operation is necessary, the automatic recovery operation is performed (step S2 in FIG. 5), and the printing operation is performed by controlling the motor 9 and the ejection head 3 (step S3 in FIG. 5). If it is determined in step S1 that the automatic recovery operation is not necessary, the printing operation is immediately performed (step S3 in FIG. 5). When the printing operation in step S3 is completed, the control unit 60 determines whether there is a next printing command (step S4 in FIG. 5). If there is a printing command, the control unit 60 returns to step S3 to perform a new printing operation. . If there is no print command, a capping operation is performed (step S5 in FIG. 5), and the elapsed time management unit 66 recognizes this point in time as the elapsed time is calculated (step S6 in FIG. 5).

In the above description, the elapsed time is a substantial elapsed time from the time when ink is discharged immediately before the recovery operation to the recovery operation. In this case, the ink discharge includes a printing operation and a preliminary ejection operation. Ink discharge from the nozzle in the nozzle or forced discharge from the nozzle by a suction operation is included. Accordingly, when a new printing command is entered again and a printing operation is performed or a recovery operation is performed by a user operation, the elapsed time is updated and the time is counted each time. Is.
This elapsed time indicates a substantial drying time for the ink to be discharged from the nozzle by the recovery operation when performing the recovery operation. That is, it can be considered that the drying of the ink inside the nozzle starts from the time when the ink stays inside the nozzle after the discharge or suction operation is finished. The elapsed time indicating the substantial ink drying time is an important factor representing the degree of progress of ink drying inside the nozzle, and is effectively used in mode selection of a recovery operation to be described later.

  In the above description, whether or not the automatic recovery operation is necessary in step S1 is determined based on the ease of drying of ink during standby, such as the type of ink used. That is, the purpose of the automatic recovery operation is to discharge the dried ink inside the nozzle and restore the ejection performance. Therefore, when it is clear that the drying has not progressed, the automatic recovery operation is not necessary. It is judged. For example, the case where the user himself / herself performs a recovery operation command prior to the print command, or the case where the elapsed time is sufficiently short corresponds to the case where the automatic recovery operation is unnecessary. In the printer 1 of the present embodiment, whether or not the automatic recovery operation is necessary is determined by referring to the elapsed time.

(Automatic recovery operation)
Next, the flow of the automatic recovery operation will be described along the flowchart of FIG. 6 with reference to FIGS. FIG. 6 is a flowchart showing the flow of the automatic recovery operation. FIG. 7 is a diagram illustrating an example of an operation mode selection table related to the automatic recovery operation.
The automatic recovery operation starts from the capping state (the state shown in FIG. 3A). First, the humidity sensor 26 detects the humidity in the space 35 (see FIG. 3A) according to a command from the control unit 60 (humidity). Step S12 in FIG. 6 as a detection step). Next, the mode selection unit 65 of the control unit 60 stores the detected humidity information and the elapsed time information managed by the elapsed time management unit 66 in the recovery operation mode storage unit 67 shown in FIG. The operation mode to be executed is selected from the table (step S13 in FIG. 6 as a condition selection step). As shown in FIG. 7, preliminary discharge operation and suction operation are prepared as operation modes. Further, the suction operation is a normal suction operation in which the suction amount and suction speed are relatively small, and the suction amount and suction speed are relatively small. It is divided into large powerful suction operation.

If the preliminary discharge operation is selected in step S13, it is determined that the suction operation is not performed in step S14 of FIG. 6, and the preliminary discharge is performed according to the conditions (drive signal mode, number of discharges) stored in the recovery operation mode storage unit 67. The operation is performed (step S17 in FIG. 6 as a discharging step). By this preliminary ejection operation, the dried ink is discharged from the nozzles, the ejection performance of the printer 1 is recovered, and a series of recovery operations is completed.
If the normal suction operation or the strong suction operation is selected in step S13, it is determined in step S14 in FIG. 6 that the suction operation is performed, and the conditions stored in the recovery operation mode storage unit 67 (the rotation of the suction pump motor 39) The suction operation is performed according to the amount and the rotation speed (step S15 in FIG. 6 as a discharge step). By this suction operation, the dried ink is discharged from the nozzle, and the ejection performance of the printer 1 is restored. Then, the ink remaining on the ejection surface 13 (see FIG. 3A) is wiped off by the wiping operation (step S16 in FIG. 6), and the ink that has flowed back into the nozzles is discharged by the preliminary ejection operation (step S17 in FIG. 6). Thus, a series of recovery operations is completed.

Here, the selection table of FIG. 7 will be described in detail with reference to FIG. FIG. 8 is a reference diagram for explaining the effect of the present invention, and is a diagram showing the relationship between the elapsed time in the capping state and the humidity of the sealed space by the cap member.
As shown in FIG. 8, the humidity of the space 35 (see FIG. 3) in the capping state maintains a substantially saturated state (90 to 100%) for a certain period, and shows a behavior that rapidly decreases when the elapsed time exceeds Tc. . This sudden decrease in humidity occurs when almost no water remains in the ink held in the liquid absorbing material 34 (see FIG. 3) in the cap member 15. The drying of the ink inside the nozzle proceeds rapidly.

  Depending on the type of ink used, in the case of the ink used in the present embodiment, in the state where the humidity is saturated, the dried ink can be discharged even by the ejection operation. The discharge performance can be recovered by the discharge operation. On the other hand, in a state after the humidity has dropped sharply, the viscosity of the dried ink is too high to be ejected by ejection, and it is necessary to forcibly eject the ink by a suction operation to restore the ejection performance. is there. In particular, in a state in which a long time has passed after the humidity is lowered, a part of the ink inside the nozzle is in a solid state, and thus it is necessary to recover the ejection performance by a powerful suction operation.

  However, the time Tc varies depending on the installation environment of the printer 1 (see FIG. 1) and the initial amount of moisture contained in the liquid absorbing material 34 (see FIG. 3). That is, Tc becomes short in a dry environment, and Tc becomes long when the initial moisture content of the liquid absorbing material 34 (see FIG. 3) is large. For this reason, the conventional method of simply determining the conditions for the recovery operation based on the elapsed time cannot take into account such Tc variation conditions. In other words, if the selection area of the suction operation is set wide in order to place importance on the reliability of the recovery operation, the amount of ink discharged and the time required for the recovery operation increase. If an attempt is made to reduce the required time, the reliability of the recovery operation is lowered.

  On the other hand, the mode selection unit 65 (see FIG. 4) of the present embodiment detects the humidity of the space 35 (see FIG. 3) and reserves that the elapsed time is less than Tc if the humidity is 90% or more. Select the discharge operation. Further, when the humidity is 50% or more and less than 90%, taking into account the elapsed time which is the substantial drying time of the ink, if the elapsed time is less than 30 days, the preliminary ejection operation is performed and the elapsed time is 30. If it is more than a day, the normal suction operation is selected. Further, when the humidity is less than 50%, the preliminary discharge operation, the normal suction operation, and the strong suction operation are selected in consideration of the elapsed time. As described above, the recovery operation can be performed more appropriately by selecting the recovery operation condition based on the humidity of the space 35 (see FIG. 3) in the capping state.

The present invention is not limited to the above-described embodiment.
For example, the liquid ejection apparatus according to the present invention is not limited to a so-called inkjet printer for paper printing, and a functional liquid containing various functional materials such as a light emitting material and a conductive material is applied to an industrial substrate. Industrial devices such as a display body manufacturing apparatus and an electrode forming apparatus that are configured to be discharged are also included.
Further, in selecting the condition for the recovery operation (step S13 in FIG. 6), selecting the recovery operation mode based on both the elapsed time and the detected humidity is a weighting requirement for optimizing the recovery operation. The selection may be made only by the detected humidity.
The humidity sensor 26 may be provided in the cap member 15. In this case, it is desirable to protect the humidity sensor 26 from ink by using a different cap member for the suction operation.
The conditions for the preliminary ejection operation may be further divided based on the humidity or elapsed time of the space 35. For example, it is conceivable to change the number of ejections depending on the humidity.
Further, the elapsed time may be a substantial time, and does not strictly require the instant at which ejection is finished or the moment at which suction operation is finished to be calculated. That is, the elapsed time (step S6 in FIG. 5) may be calculated before the capping operation (step S5 in FIG. 5) or just before the end of the printing operation (step S3 in FIG. 5).
Moreover, each structure of each embodiment can combine these suitably, can be abbreviate | omitted, or can be combined with the other structure which is not illustrated.

1 is a schematic perspective view illustrating an example of a liquid ejection apparatus according to the present invention. The schematic perspective view of an ejection head. (A) is sectional drawing which shows the relationship between the discharge head concerning a capping operation | movement, and a maintenance mechanism. (B) is sectional drawing which shows the relationship between the discharge head concerning a suction operation, and a maintenance mechanism. FIG. 2 is a block diagram illustrating an electrical configuration of the printer. 6 is a flowchart showing a flow of a printing operation. The flowchart which shows the flow of automatic recovery operation | movement. The figure which shows an example of the selection table of the operation mode which concerns on automatic recovery operation | movement. The reference diagram for demonstrating the effect of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer as liquid discharge apparatus, 2 ... Paper as discharge target object, 3 ... Discharge head, 4 ... Carriage, 10 ... Guide rod, 12 ... Maintenance mechanism as suction means, 13 ... Discharge surface, 14 ... Wiper blade , 15 ... Cap member as capping means, 23 ... Nozzle opening as nozzle opening, 25 ... Recess, 26 ... Humidity sensor as humidity detecting means, 27 ... Nozzle area, 28 ... Detection area, 29 ... Dummy area, 30 ... Tube constituting the suction means, 31... Suction pump constituting the suction means, 33... Waste liquid storage section, 34... Absorbing material, 35. Control unit as means, 64... Drive signal generation circuit, 65... Mode selection unit, 66 .. elapsed time management unit, and 67.

Claims (11)

A liquid ejection apparatus that includes a nozzle for ejecting liquid and performs a recovery operation for discharging the liquid from the nozzle to the outside of the ejection object prior to a drawing operation for ejecting the ejection object.
Capping means capable of sealing the nozzle opening;
In a state where the opening of the nozzle is sealed by the capping means, humidity detecting means for detecting the humidity of the space facing the nozzle opening;
A liquid ejecting apparatus comprising: a condition selection unit that detects humidity of the space prior to the recovery operation and selects a condition of the recovery operation based on the humidity.   The liquid ejection apparatus according to claim 1, further comprising a suction unit that sucks the liquid from the nozzle, and performing the recovery operation using the suction unit.   The liquid ejection apparatus according to claim 1, wherein the recovery operation is performed by a preliminary ejection operation for ejecting the liquid to the outside of the ejection target.   4. The liquid ejection apparatus according to claim 1, wherein a discharge amount of the liquid in the recovery operation varies depending on a condition selected by the condition selection unit. 5.   The condition selection means acquires a substantial elapsed time from the discharge of the liquid immediately before the recovery operation prior to the recovery operation, and based on the elapsed time and the detected humidity, The liquid ejection apparatus according to claim 1, wherein a condition is selected.   The said suction means seals the opening of the nozzle by the capping means, and performs a suction operation of sucking the liquid from the nozzle by depressurizing the sealed space. The liquid ejection apparatus according to any one of the above.   The liquid ejection apparatus according to claim 6, wherein the humidity detection unit is disposed in the vicinity of the opening of the nozzle and can be sealed together with the opening of the nozzle by the capping unit.   The liquid ejecting apparatus according to claim 7, wherein the capping unit seals the opening of the nozzle without including the humidity detecting unit when the suction operation is performed. The capping means is a cap member that can be sealed around a certain region of the ejection surface where the opening of the nozzle is formed,
The ejection surface is opposed to the detection area, the nozzle area where the nozzle opening is formed, the detection area where the humidity detection means is disposed adjacent to the nozzle area, and the nozzle area. The liquid ejecting apparatus according to claim 8, further comprising a dummy region that is a region to be operated.   The liquid ejection apparatus according to claim 9, wherein the humidity detection unit is disposed in a recess formed in the ejection surface. In a liquid ejection apparatus that includes a nozzle for ejecting liquid to an ejection target, a recovery method that is performed prior to a drawing operation that performs ejection on the ejection target,
A discharge step of discharging the liquid out of the discharge target from the nozzle;
Prior to the discharging step, in a state where the opening of the nozzle is sealed by the capping means, a humidity detecting step for detecting the humidity of the sealed space;
A recovery method, further comprising: a condition selection step for selecting a condition for the discharge step based on the humidity detected in the humidity detection step.

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